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Design for the Environment/Ontario Residential Roofing Materials

Roofing shingles are important to residential units as they protect the roof of a house from outdoor elements. With the large selection of styles, colours, and materials, shingles must not only withstand extreme seasonal conditions, but compliment the architecture of the home. Shingles vary in cost, thus a more expensive material choice can result in increased property value and higher social standing.

Summary
This study focuses on three common forms of residential roofing materials, and compares each alternative based on their function, environmental impact and cost to the user. The three types of shingles that will be further compared include asphalt fibreglass composition, wood, and aluminum. Fibreglass-based shingles are composed of a fibreglass reinforced mat saturated with an asphalt mixture. Asphalt roof shingles have been designed to protect a roof through their manufacturing and installation process. Wood roofs most commonly come in the form of red cedar shakes. Along with their natural resistance to decay, red cedar roofs are chemically treated to improve sustainability. The high strength and toughness of aluminum makes it a viable roofing option by resisting damage from the impact of hail and other solids.

This study can be useful to anyone looking to re-roof a residential house. On a large scale, a home building company may find the following recommendations and conclusions particularly interesting. The motivation behind this analysis was to look at the current trends in residential roofing materials, and decide whether the most common forms of roofing have functional, environmental and cost advantages. The comparison can serve as a basis for the final recommendation of one design alternative for residential roofing materials.

Project Information
MIE 315 Section 02

Group B22

Holly Johnson (Holly)

Kyle DuPont (Kdupont)

Shyra (Shyra)

Mark (Mark.Osmokrovic)

Highlights and Recommendations
Asphalt and fibreglass composition shingles are currently used in the majority of homes, and thus served as a baseline for comparison. Two alternatives to asphalt shingles are aluminum and Red Cedar Tapersawn Shakes, which will be referred to as cedar shakes.

Asphalt shingles have been the standard among homes in North America for several decades. Information for the figure to the right was provided by The Freedonia Group, and shows the detailed breakdown of the material used in roofing residential homes in the United States from 1992-2007. This analysis was completed to revaluate the use of asphalt, and determine if either aluminum or cedar is a better alternative. It was assumed a house in Ottawa, Ontario, Canada with a roof of 1500 square feet was being protected for 50 years. A conclusion was recommended based on a functional analysis, a qualitative life cycle analysis, a quantitative life cycle analysis, a cost analysis, and society’s perception.

After analyzing each of these factors, it was determined that asphalt should continue to be used as a primary roofing material. However, this conclusion is only valid for the upcoming 25 years, after which time the net consumption of oil will reach the net production. After year 25, the production of asphalt shingles will be detrimental to the environment because it will involve a depletion of a fossil fuel.

For the long-term, cedar shingles are optimal for the environment, but aluminum shingles are best suited for the consumer. This is because the cost of cedar shingles is more than twice that of aluminum. Despite scoring lower in the SLCA, aluminum shingles produce less total global warming potential, releases, and require less energy than cedar shingles. Therefore, it is recommended for the long run that aluminum be used as the primary roofing material.

Functional Analysis
The primary purpose of residential roofing shingles is to protect the house and its inhabitants from the vast array of outdoor elements. Drastic changes in temperature, precipitation, and wind can occur over a short period of time. In terms of a house located in Ottawa, Ontario, the roof must be able to withstand the cold weather and abundant precipitation associated with a frigid winter, as well as the scorching heat of the summer sun.

Asphalt, aluminum and cedar roofing options have their own advantages and disadvantages when looking at the full spectrum of their purpose; for example, asphalt shingles are most easily installed, aluminum’s toughness makes it resilient to the impact of hail, and cedar’s natural appearance provides an aesthetic appeal to the house. However, these benefits do not alone justify a level comparison between the design alternatives. In order to ensure asphalt, aluminum and cedar roofs have comparable functions, each roofing material is analyzed in terms of their tolerance to extreme weather conditions.

Upon researching the functionality of each option in varying weather conditions, it was determined that each of the design alternatives could fulfil their year round purpose on the roof of a house in Ottawa, Ontario. However, the major variable within the comparison deals with the expected lifespan of each option. Aluminum shingles can typically last 50 years without replacement, while standard asphalt and cedar options can only be functional for 25 years. Thus, in order to accurately compare the three options, this study will look at a 50-year time period. In this time, aluminum shingles will be installed once and last until the end of the study, while both the asphalt and cedar roofs will be installed once at year 0 and then again at year 25.

It is concluded that with this consideration of varying life spans, the three options for residential roofing materials can be accurately compared against each other in cost, environmental and societal analysis. More details regarding the advantages and disadvantages of asphalt, aluminum and cedar roofs can be found here.

Economic Input-Output Life Cycle Analysis
The Economic Input-Output Life Cycle Analysis allows for the comparison of design alternatives by quantifying the environmental impacts corresponding to an economic input into a specific economical sector. This analysis model considered resource extraction and manufacturing as one stage, transportation as a second stage, and end of life as a third stage. In analyzing the output for each of these three studies, the largest environmental impacts are ranked according to the top five contributing sectors.

The environmental impacts between alternatives are evaluated through: substance releases, such as the equivalent metric tonnes of carbon dioxide for Global Warming Potential gasses (GWP), carbon monoxide and dioxide emissions; the Tera Joules of energy used; and kilograms of all toxic releases and transfers (land, water and air).

The results of this showed that in fact, asphalt shingles produced the least environmental impact overall. Aluminum had the highest impact of the alternatives during its manufacturing and end of life stage (recycling) in total releases. Cedar shakes had the second highest impact, which was trailed closely by asphalt shingles. The same rank followed in the other two sectors, except asphalt was clearly the best alternative by a larger margin. Based on this analysis, the asphalt shingle produces the least environmental effects for a 25 year life span. More detailed information regarding each roofing alternative can be found here.

Streamlined Life Cycle Analysis
A streamlined life cycle analysis considers all the stages in the life cycle of shingles: Resource Extraction; Product Manufacturing; Product Delivery; Product Use; and Disposal and Recycling. Each stage was then evaluated on the following criteria: material choice; energy use; solid residues; liquid residues; and gaseous residues.

The product delivery phase was ranked based on the energy used to transport the shingles. The energy used is dependent on the distance the truck travels from the manufacturing plant to the distribution centre in Ottawa, Ontario. Asphalt shingles travel from Brampton to Ottawa within Ontario, but with a weight of 230 pounds per square. Aluminum smelters are located in Quebec along the Saguenay River, and it is assumed the shingle production plant is located close to the smelter, the product would be transported 670 km by truck to Ottawa, Ontario. The weight per unit area of aluminum roofing is five times less than that of asphalt or cedar at 40 lb per square. Cedar shingles weigh 205 pounds/square and need to be transported from British Columbia to Ontario.

The matrix assesses asphalt, aluminum, and wood shingles and the results are summarized in the following table.

Resource extraction and product manufacturing were weighted at 30% because they have the biggest impact on the environment. Since product delivery and use were similar to all alternatives, they were each weighted at 10%. The disposal and recycling phase was weighted at 20%. The final results for asphalt, aluminum, and cedar shingles were respective rankings out of 100 of 59.5, 61, and 77.5. Details on each of the alternatives can be found below.

Cost Analysis
The economic analysis was completed on the assumption that a house in Ottawa, Ontario, Canada with a 1500 square foot roof was being protected for 50 years. All costs were converted to present worth assuming a 2% inflation rate. During the 50 year lifetime, the roof composed of asphalt shingles, as well as the roof with cedar shakes, will be replaced at year 25. The costs considered are considered from the perspective of the home owner and included the installation, maintenance, and end of life costs.

It was found that asphalt shingles require no maintenance, but had a total installation cost of $3509.05 and a disposal cost of $222.84. Aluminum shingles require no maintenance, but had installation costs $3634.05 and had a return of $0.05 for disposal. Cedar shakes require $6741.45 for installation, $1494.31 for maintenance, and $250.83 for disposal. From these results, it is clear that aluminum shingles are the most cost effective because it does not require two disposal or installation fees. The costs for each design alternative are summarized in the graph located to the right. More details regarding the advantages and disadvantages of asphalt, aluminum and cedar roofs can be found below.

Societal Analysis
Due to the nature of the product, its effect on the greater part of society is mostly aesthetic. Society’s perception of a roofing alternative will affect a homeowner’s purchasing choice. Also, the affordability of the product for the homeowner is also a major factor.

The widespread use of asphalt was attributed to its relatively low cost. The comparatively greater expense for aluminum or cedar roof was justified by aesthetic appeal; cedar shingles have a natural, authentic appearance; aluminum shingles are versatile in terms of graphic design. Aluminum shingles also involve the benefit of convenience due to low maintenance. The details for each alternative can be found here.

Asphalt
Sudden variations in ambient temperature cause the shingles to rapidly expand and contract, resulting in thermal stresses. Hail can fracture or cause a significant loss in the asphalt granules, which may result in short term leaks or reduce the lifespan of the shingle. Since asphalt shingles are installed with an overlapping double layer, the damaged shingles do not need to be replaced immediately. Strong winds are likely to lift the edges of shingles resulting in warping and possible tearing. This can lead to water damage as more shingles are torn from the roof, thus exposing the roof deck.

Aluminium
Aluminum shingles employ a four-sided interlocking installation system. The tight seal from interlocking helps resist wind damage and prevent leaks. The interlocking and slippery aluminum surface work to shed snow and ice rapidly, preventing damming and, in turn, leaks. Installing aluminum shingles is less labour and energy intensive compared to the other alternatives because they are five times lighter per unit area than either alternative.

An aluminum roof inhibits moss growth, retards the spread of flame, and is not liable to rust, slit, rot or curl.

A disadvantage to aluminum shingles is a higher noise level upon the impact of hail or heavy rain on the metal surface. While asphalt and wood are better at absorbing the noise, aluminum shingles depend on the felt layer below the shingles to dampen the sound.

Cedar
Wood has been a competitive option as a roofing material for a significant portion of building history. Red cedar shakes can last up to 40 years if the roof is properly maintained and the wood is chemically treated to protect against decay and fire. It costs approximately $40 per square to fire-treat the wood, which is often required by law in high-risk forest fire areas. After being treated, typical cedar shakes can withstand 1 ¾ hail and winds as high as 200 mph. To prevent water build-up or damage due to snow and precipitation, cedar shakes are best suited for a roof with a minimum slope gradient that increases in height by four feet for every twelve feet away from the eaves.

In terms of maintenance, red cedar shakes require cleaning every five years to remove any mould growth and mildew. Although cedar shakes are generally suitable for most geographic regions, cracking and warping are possible in harsh climatic changes due to water seepage into the wood grain. This risk can be reduced if the shakes are initially treated and properly maintained, making cedar an aesthetically pleasing option that is suitable for all climates.

Asphalt
For the manufacturing stage of asphalt shingles, the highest contributor to GWP emissions was power generation and supply because this is an energy intensive process. The total toxic releases and toxic transfers are attributed to copper mining as this is a highly toxic process and the copper is used for the algaecide in the asphalt mixture.

Petroleum refineries have a high impact due to the release of toxic chemicals during the distillation process. However, because asphalt is a by-product of crude oil refinement, the environmental impacts do not need to be considered, as they occur regardless of whether the asphalt is used or not. This argument is valid for gas and oil extraction.

The transportation of shingles from the manufacturing location in Brampton, Ontario produces almost equal amounts of GWP emissions as the manufacturing stage. The remaining contribution is due to the releases from refining petroleum to produce gasoline and diesel fuel and the mining of the materials needed to construct the transportation vehicles.

The end of life of shingles after 25 years requires their disposal in landfills. The total weight of the refuse is approximately 1.667 tonnes, which is only solid waste. However, according to the model, disposing this waste in a landfill produces enough economic activity in the waste management sector to produce the highest releases of GWP emissions of all life stages at 0.499 metric tonnes. The total releases (including toxic substances) is also the highest of the three phases, making the disposal of asphalt shingles the highest contributor to the negative environmental impacts.

Aluminium
For the manufacturing stage of aluminum shingles, a custom analysis was used that combined several industry sectors that make up the steps within the manufacturing processes. Those industry sectors included; “Aluminum sheet, plate, and foil manufacturing”; “Sheet metal work manufacturing”; and “Electroplating, anodizing, and coloring metal” with corresponding inputs in 1997 USD of $142.16, $800.44, $1 320.54, respectively. The second analysis was completed for product transportation from the manufacturing plant to the distributor, a total of 670 km away in Quebec. Using the traveling distance and tonnage of product, the cost of transportation was calculated to be $35.57 1997 USD.

The third analysis describes the environmental impact of recycling the used aluminum at the end of life phase. The salvage cost for the material of $413.96 1997 USD was input for the Secondary Smelting and Alloying of Aluminum sector.

The EIOLCA predicted a total of 26 MJ of energy used for the manufacturing process. The manufacturing process showed a total of 4.79 kg of toxic releases; 3.64kg of which were solid residues. This quantity can be attributed to aluminum hydroxide sludge produced in the anodizing process. The most prominent form of GWP releases by far for the manufacturing process was shown to be CO2. At 1.74 MT it was almost ten times more prominent than the next gas and represented over 80% of the total GWP. CO2 was also significant for product delivery and recycling, as it is produced from combustion engines and smelting facilities.

Cedar
A custom model was used for the manufacturing of cedar shakes, in order to account for both the cutting of the wood and the preservation treatment of the cedar. In total, the production and treatment of cedar shakes contributes 1.68 metric tonnes of C02 equivalent (MTCO2E) of GWP, where power generation and supply accounts for nearly one third of this value. This value may be larger than in reality, since the model is based in the United States where more than 44% of the power plants are coal-fired, which emit large amounts of SOx, CO2, and NOx. In Canada, the percentage of coal-fired power plants is much lower at 6.3%, as a large fraction of our power comes from refined petroleum, hydroelectricity and nuclear power.

The manufacturing of cedar shakes contributes 0.631 kg of toxic releases, which is primarily due to the mining of copper, nickel, lead and zinc. Mining requires a large amount of land removal for a small quantity of usable metal, contributing to toxic land releases such as lead, which is found naturally in the earth’s crust and is a dangerous neurotoxin to humans.

In considering the delivery stage of cedar shakes, truck transportation is the major contributor of conventional air pollutants, releasing 0.083 metric tonnes of CO. This impact is most likely due to the incomplete combustion of the gasoline and diesel powered engines of the tractor-trailers used to transport the products. The significance of these engine releases is also depicted in the GWP index, where the truck transportation sector is the second highest contributor of CO2 and other greenhouse gases.

The disposal of the red cedar shakes upon removal contributes most negatively to the environment in terms of methane emissions and toxic land releases. Waste management and remediation services accounts for 98% of the methane emissions at this stage, emitting 0.742 MTC02E of the total 0.75 MTC02E. As a greenhouse gas, methane is produced by the decomposition of landfill materials in the absence of air. The toxic land releases associated with the disposal of the cedar shakes can be accounted for by the chemicals used to treat the wood. CCA (chromate copper arsenate) is a common wood preservative, which contains the poisonous chemical of arsenic.

Asphalt
The resource extraction of asphalt involves petroleum refinement, which has heavy crude oil as a by-product, which asphalt is made from. Fibreglass matting is used as a base to support the asphalt within a shingle. The energy necessary to create fibreglass involves high temperatures of 2000°C.

Asphalt shingles are reinforced with fibreglass, both of which must be virgin materials during manufacturing. The asphalt then needs to be oxidized, which involves heating the material to above 200°C.

In Canada, approximately 1.25 million tonnes of asphalt based roofing material is discarded annually in landfills However, there are many alternatives to this process. According to Alberta Construction Magazine, Nova Scotia uses shredded shingles as a main ingredient in gravel on multi-use trails. Halifax C&D Recycling Ltd. currently shreds asphalt shingles into grit and flake, which is then sold to Lafarge as an alternative fuel for its cement kiln. However, the use of asphalt as a fuel source has not been pursued aggressively due to public anxiety and possible waste products.

Lafarge uses scraps from the manufacturing line as an additive in its concrete mixture. There are possibilities for the use of waste shingle in highway material, but pilot studies have yet to be conducted. As it remains, the fee of dumping asphalt shingles in landfills is much lower than the cost of recycling, and unfortunately will probably remain this way without some form of government regulation

Aluminium
29% of aluminum products manufactured in the United States are made using recycled material. Therefore, this analysis will assume that 29% of the material used to manufacture shingles is recycled, and the remaining 71% is virgin material. The use of recycled aluminum requires 5% of the energy to be produced and results in less than 5% of the emissions than virgin material. .

On average, 7 to 12 kWh of power is required to produce one pound of aluminum. A large amount of energy is used to heat and pressurize the digesters that separate aluminum oxide from the minerals in bauxite ore. An electrometallurgical smelter releases approximately around 1.223 metric tonnes of carbon dioxide for every metric ton of aluminum produced.

The product manufacturing stage involves sheet metal forming which is easily formed and does not require excessive amounts of energy. The aluminum shingle then goes through a protective coating process, which normally involves an anodized finish. This process requires 0.5245 kWh of energy for 1500ft2 (Sulfuric, 2008). Anodizing produces large volumes of aluminum hydroxide sludge, although, by reusing the acid baths, this amount can be reduced by 85% for every subsequent dip ( . The only liquid and gaseous residues released for the manufacturing process are potential non-point discharges of sulphuric acid.  If dissolved in water it can have moderate short term toxicity on aquatic life.

Aluminum shingles require no maintenance during their lifetime and are expected to last for 50 years or more. The thermal conductivity and ability to reflect radiant heat minimizes the heat dissipated into the home from radiant sunlight. Aluminum shingles reflect 70% of the sun's energy, resulting in a reduction of 34% in heat increased, when compared to asphalt shingles.

Aluminum shingles are fully recyclable. However CO2 is released during the re-melting process. Used and coated aluminum can be sold for approximately 90¢ per lb.

Cedar
The resource extraction phase of cedar shakes is very environmentally friendly because wood is a renewable resource, non-toxic, biodegradable and recyclable. The most significant form of residue during this stage is the sawdust from saw milling operations, which can be used as a rooting medium and for construction purposes.

In the manufacturing phase, the chemicals used to treat the wood against insects, decay, and fire are classified as Chromate Copper Arsenate (CCA). Arsenic is a known carcinogen to humans, and if not handled properly, even small amounts of residue could be dangerous.

Wood accounts for 47% of the raw materials market in the United States, yet it utilizes only 4% of the total energy used for raw materials manufacturing, making it very energy efficient. However, the chemical treating requires the shakes to be kiln dried at temperatures above 100oC for as long as 24 hours. The chemical impregnation takes place after the wood has been dried in a vacuum, and occurs at pressures around 1000 kPa.

In the product use phase, cedar shakes require a chemical re-treatment every 5 years to prolong the life of the roof and prevent against common threats to cedar such as mould and mildew. This treatment can be painted on after power-spraying the roof, emitting a gaseous residues consisting primarily of ammonia. Another significant environmental impact during the use phase of shakes deals with heating and cooling costs of the house. Tests have shown wood shingles are able to keep an attic 15°C cooler in intense summer heat, when compared to a roof with asphalt shingles, reducing energy costs by nearly 20%.

At the end-of-life stage, wood has the advantage of being recyclable and reusable with little additional energy. Wood is also biodegradable, so it will eventually break down if it does end up in a landfill. Alternative disposal options include selling the scraps to companies who can convert it to cedar ground chips and hog fuel. This option is currently only commercially viable in the United States.

Asphalt
The cost of asphalt shingles was taken as today’s prices. However, when the shingles are replaced at the 25 year mark, the cost of shingles will have increased at a rate higher than inflation due to the increasing cost of crude oil. It is difficult to predict how the price of asphalt shingles will be affected as there are several contributing factors, including potential growth in the shingle recycling market. However, based on 2006 Crude Oil prices, which are fairly stable, a modest 5.4% increase was used to calculate the cost of shingles in 25 years.

The maintenance required on an asphalt roof is minimal, which is one of the reasons why it appeals to so many consumers. As long as precautions are taken, such as proper installation, attic ventilation and trimming of overhanging trees, the roof should require no maintenance until replacement. The disposal costs amounted to $222.84. The total cost of the project, in present worth, is $3731.89.

Aluminium
The major cost to the homeowner associated with aluminum shingles is the cost of installation. The cost of materials (shingles, nails, and felt matting) is $3132.09 US and the labour of installation was calculated to be $501.96 US giving a total of $3634.05 US. There are no maintenance costs for aluminum shingles, and the disposal, in fact, provides a return with the sale of recycled aluminum. However, considering an inflation rate of approximately 2%, the return on secondary aluminum amounts to less than 5¢ US in present value.

Cedar
The initial cost of the cedar shakes, felt matting, galvanized nails, and installation labour were taken from a distributor in today’s prices. It was assumed that the cost of cedar shakes will not rise more than the inflation rate over the next 25 years, since this renewable resource is in abundant supply due to Canada’s sustainable forestry management. After considering this, the total initial costs from years 0 and 25 equal $6741.03 CAD.

Maintenance of cedar shakes includes the cost of labour and the materials required to clean the roof and re-treat the shakes with a cedar wood protection treatment. These maintenance costs will occur every five years between year 5 and year 20 and then again between year 30 and 45. During the use phase of the cedar shakes, mould and mildew can form on the roof surface if not properly maintained and treated. Cedar shakes are more prone to decay by mould growth and insects than any other roofing material. If mould has initiated the decay of the shakes, the resident of the home must pay to have the roof pre-maturely replaced. This indirect cost is highly subjective on the owner’s habits, and is therefore unquantifiable. If proper maintenance instructions are followed, the total cost over the 50 year time period is $1,454.30.

Disposal occurs at the end of each 25 year segment. The disposal costs at years 25 and 50 include the labour to remove the roofing material as well as the local landfill cost. In the end, the total disposal costs amount to $250.81.

In considering the present worth of the initial, maintenance and disposal costs, the total expense of purchasing and maintaining a cedar roof for a 50 year period is $8,446.17.

Asphalt
The use of asphalt shingles in North America is vast, with over three quarters of residential homes using asphalt shingles. The main reason for this is because they are the most economical method of roofing a home. As the shingle market became more competitive, this forced shingle manufacturers to produce more aesthetically pleasing shingles, in a variety of different colours. However, because asphalt shingles are very economical they do not add much value to a house, as other means of roofing are more expensive and usually more aesthetically pleasing.

Aluminium
Homeowners pay a significantly greater amount of money for an aluminum shingled roof than the asphalt baseline. There are several motives for this. As explained in the functional analysis and SLCA, aluminum shingles require no maintenance. From this perspective, the consumer is paying for convenience. Aluminum shingles also have the versatility of being made to look like other types of roofing. They can be formed into various shapes, and dyed with a wide range of colours during anodizing, to appear as cedar shakes, slate, stone or tile. The extra cost pays can also be attributed to this aesthetic value. Both factors increase the value of a home and, therefore, could help increase the resale value of the house.

Cedar
Aside from its functional advantages and technical specifications, a cedar roof adds significant monetary value to a residential home. The “Residential Cost Handbook” suggests that a cedar roof increases the value of a house by $2.00 per square foot. According to this estimation, a cedar roof would add $3000.00 to the value of the house. This increase would greatly benefit the homeowner at the time of resale, and might encourage residents to choose cedar when re-roofing their house.


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Prioritizing Content

Prioritizing Content
After identifying a list of potential tasks and subtasks that may need to be trained, you will need to identify and select those tasks that should be trained. As an instructional designer, you need to be careful not to select and train tasks just because they were identified during the Task Analysis. Many designers identify training content by using their best estimation of what needs to be trained ("best guess"), but that is not the best way to select the content. Instead, you should adopt and use a systematic process that will help you identify the correct tasks based on reasoning and analysis.

There are many reasons why you may not want to select a task for training. The following list identifies some common reasons for not selecting a task for training:
 * The student should already possess the knowledge, skill or ability/attitude (KSA)
 * The task will be trained later after scaffolding is provided
 * The task is accomplished infrequently
 * There isn’t enough time
 * The return on the investment is not adequate to justify the cost

QUESTION #1: Why would you not want to train a task that is accomplished infrequently?

Think about how you would answer this question before clicking on the answer below.

ANSWER #1

Instruments for Prioritizing Content
There are a variety of instruments (tools) that can be used to help you select and prioritize content for physical tasks that need to be trained. The three instuments in the table below are the tools we recommend. When selecting the appropriate tool(s) to use, review them in the order listed.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Prioritizing Content


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Seed production and gene diversity

Genetic diversity is often a major consideration in e g forest crops.

Consider the gene pool of a seed orchard crop. The gene pool is large as there are many seeds in a seed crop, so there is no genetic drift. The probability that the first gene originates from genotype i in the seed orchard is pi, and the probability that the second originates from genotype j is pj. The probability that these two genes originating from the orchard genotypes i and j are identical by descent (IBD) is θij. Thus the coancestry (or "coefficient of kinship"; "coefficient of relationship" is a similar measure which can be computed) between genotype i and j. The probability that any pair of genes is IBD can be found by adding over all possible pairs of genes from N contributorsFormula for the group coancestry (from which gene diversity can be obtained) of seed orchard crops. $$ \sum_{i=1}^N \sum_{j=1}^N $$ pipjθ. The group coancestry of a seed orchard crop can be divided in two terms, one for self-coancestry and one for cross-coancestry. Similar expressions has been used many times before, it has similarities to the concept of effective population size as defined by.

title: Seed production and gene diversity


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Talk:Seed production and gene diversity

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title: Talk:Seed production and gene diversity


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Using the All Critical Learning (ACL) Model

All Critical Learning (ACL) Model
When evaluating complex tasks it is often important to be able to customize the criteria to be evaluated. For this reason, the ACL instrument is often the preferred tool because it allows the user to tailor the evaluation criteria to be evaluated to the situation. The user can select criteria like:
 * What is the immediacy of performance? (How soon will will the task be performed after being trained?)
 * How difficult is the task to perform?
 * How often is the task performed?
 * How critical is the performance?
 * Are there important safety concerns that need special consideration?
 * What are the consequences if the task is not performed correctly?

The ACL Data Analysis Form not only provides a form where you can tailor the evaluation criteria, but it also allows each criteria to be independently evaluated and rated on a scale from 0 to 7 where a higher final rating indicates a greater need for training. The typical rating scales is as follows:
 * 0 = Not Necessary. No need to consider; already identified as not requiring training.
 * 1 = Weekly important. These probably don't need to be trained either.
 * 3 = Important. Consider including as supporting information
 * 5 = Strongly Important. These should definitely be trained if possible.
 * 7 = Essential. Must be trained; an absolute must.

When all criteria for a task are graded, the scores are totaled and entered in the last column. In the example there are 9 critera, so the maximum final rating would be 63. (9 criteria times 7 points each = 63 points)

Experts consider the ACL model [also known as the Multiple Factor Model (MFM)] the best model because the user can tailor the evaluation criteria to fit the context for its use. Adding selection criteria makes the instrument harder and more time consuming to use, but it also makes it more accurate when used carefully.

ACL Job Aids

 * [[Media:The_ACL_Data_Analysis_Form.pdf | ACL Data Collection Form]]

 * [[Media:The_ACL_Data_Analysis_Form_Instructions.pdf | Instructions for using the ACL Instrument]]

 * All Critical Learning - Practical Exercise


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Content Prioritization for Standards-based Education

Content Prioritization for Standards-based Education
In contrast to the other methods of content prioritization presented here, some designers are not given latitude to disregard or eliminate content. Most often this is because the content is directly related to externally or internally imposed standards, such as OSHA-compliant safety awareness programs, or state and district academic standards required of primary and secondary schools.

Schools in particular are required to achieve a considerable number of standards, and the general consensus among administrators and teachers alike is that there are too many standards to cover uniformly and fully. Noted education consultant Dr. Robert Marzano notes that in order to cover all standards “You would have to change K-12 to K-22. The sheer number of standards is the biggest impediment to implementing standards.”

Yet state and local standards must be met. Content prioritization is essential in this case as well, though rather than discarding content altogether, the prioritization is of time and energy devoted to accomplishing each standard.

There are two main difficulties users will encounter when attempting to execute instructional design using prioritized standards:

 * 1) Evaluating standards against the specific criteria of your school or organization.
 * 2) Achieving consensus among the stakeholders regarding high, medium, and low priority standards.

Thus, the method needed will need to be adaptable and democratic. An adaptable nature will allow it to be tailored to the organization’s unique situation, and being democratic will ensure that the results are well rounded and - just as importantly – fair, meaning that teachers, trainers, and/or designers are more likely to buy into the decisions made based on the consensus.

About this Method
The method that you will learn about in this section has two stages:

 * 1) Develop additional criteria using Nominal Group Technique.
 * 2) Prioritize standards using a Decision Matrix.

The method detailed below uses an example that takes place in a K-12 setting, but it can be used for other organizations that use externally-implemented standards and/or high-stakes standardized testing.

After reading the section about the Nominal Group Technique, you will understand how it allows decision-makers to develop criteria that are important and specific to their institution and how the group ranking process promotes fairness in the adoption of the criteria in the decision-making process.

After reading the section on processing the resultant data with a Decision Matrix, you will understand how the criteria are used to prioritize the standards.

Nominal Group Planning
Nominal Group Planning allows participants to anonymously submit their ideas and rank the group results. Group discussion allows participants to debate the pros and cons for each criterion, and then anonymously revise their rankings.

Steps for Conducting a Nominal Group Planning Session

 * 1) Gather all decision makers into a group. If more than ten people are present, it may be advisable to break into subgroups, as participant attention and enthusiasm will wane if the proceedings take too long.
 * 2) The facilitator (chosen beforehand) explains the purpose and process of prioritization to all participants. This should include a clear statement of the objective of the meeting.
 * 3) Next, each member of the group should write down criteria which they feel will be useful in evaluating the standards. This should be strictly individual, as to preserve the anonymity of the author at a later stage.  This is the most unstructured step in the whole prioritization process, and because it is done individually and early in the process, it is likely that the facilitator will need to supply plenty of encouragement for participants who are still uncertain in their purpose.  It is likely that a few criteria will already be established externally, or may be particularly obvious, so the facilitator may want to use those criteria as an example.
 * 4) The facilitator will take all lists of suggestions and compile them into a master list that will be manipulatable by the facilitator and visible to all participants (such as a dry erase board or transparency on an overhead projector). The master list should not have grouped entries from the same individual list, but should be random.  If the number of decision makers and/or the number of criteria offered is substantial, offering the group a break will give the facilitator the time to compile the large list without boring the participants.
 * 5) Through group discussion, the entries in the large list should be consolidated and simplified. Undoubtedly some specific criteria will be subsumed in more general criteria, but the facilitator should warn against over-consolidating into a few criteria that are too general or broad.  For instance, ‘opportunity cost’ and ‘pecuniary cost’ should not be rolled into a general ‘cost’ criteria, as each is a very different dimension, and ‘cost’ will mean very different things to different people.
 * 6) Having reduced the master list into a consolidated list, each participant should individually (again, to preserve anonymity) compile a ranked list of criteria, where #1 is what they consider the most important criteria of prioritization. It should not be necessary for participants to rank more than ten of the criteria if the total exceeds that number.  The facilitator should remind the group that they will have the opportunity to re-rank their decisions at a later stage, so it is not imperative to take a lot of time and consideration when ranking their lists.
 * 7) The facilitator will tally the results, one individual list at a time. One point is assigned to the top ranked criteria on each list, 2 points to the second, and so forth.  The individual scores of each criterion are summed, and the criteria are ranked according to the group scores.  For example, if the group consisted of three participants with three criteria, the individual lists might look like this:
 * The ranked tally would then look like this:
 * Criteria X: 1 + 1 + 2 = 4
 * Criteria Y: 2 + 3 + 1 = 6
 * Criteria Z: 3 + 2 + 3 = 8
 * According to the group, criteria X is the most important, Criteria Z the least, and Y in between.

Next, discuss the results as a group. Participants are encouraged to voice concerns about why a high-ranked criteria should not be held in such positive regard, or why a low-ranked criteria should be elevated. The facilitator should encourage discussion among all participants, not just a vocal few. The penultimate step in the process is the same as step 6, only this time participants should be given more time to rank their lists. Facilitator once again tallies and ranks the results. The top criteria are selected for use in the Decision Matrix. The number of criteria selected depend on the situation and if some criteria were established previously to the session. However, if there is a natural break in the ranking data (such as a 50% difference in the score of adjacently ranked criterion) it generally indicates a good cutoff point.

Narrative Walkthrough for Conducting a Nominal Group Planning Session
Context:  Teachers in a large California school district have faced considerable difficulty in covering the ever-increasing number of state standards during the academic year, and the issue has been a source of friction between the educators and the demanding district school board. The board has responded by enacting a program of standards prioritization that will aid the teachers in refining their curriculum to be functional and to improve concurrency of content taught in each classroom. This is where you come in. Let’s say that you have been charged with acting as a facilitator for a group of five sixth grade social studies teachers who are prioritizing their content standards. You and the teachers have received a “prioritization packet” created under supervision of the district board that explains the general idea of prioritization and a few criteria that should be used when evaluating the standards. During a summer time Teachers’ Conference meeting your job is to guide the teachers through a Nominal Group Planning brainstorming session with the goal of discovering other criteria that can be used to prioritize the standards.

 * Beforehand: You reserve a conference room that is quiet and largely free from distractions.  You make sure that there is adequate seating for you and the five teachers who will be participating in the process.  Knowing that the process requires each participant to write, you place a stack of lined paper in the middle of the conference table along with more pencils than will be needed.  In order to indicate their seats, you place an itinerary (complete with the steps used in the Nominal Group Planning session) in front of each participant’s chair. You are also aware that a group display is needed, and you have decided to use the conference room’s whiteboard.  Erasers are accounted for and the markers are in working order, so you are confident that the meeting is ready to proceed.

 * Step 1: The participants arrive and are seated.  Because there are relatively few participants, only a single group is required.

 * Step 2: Although the teachers are aware of the purpose of this meeting, it is still a good idea to have a discussion.  You ask the teachers to volunteer reasons why prioritization will be valuable to their practice as well as any concerns they may have.  The teachers respond immediately and are very vehement in their frustrations in covering all standards, and commiserate with one another over their mutual hardships.  After a few minutes you sense that the discussion is slipping too far into negativity and attempt to turn the conversation constructive by asking the teachers how they think prioritization will help them to cover all standards.  One response is “We will finally be able to downplay the topics that aren’t of much use to our students.”  Another teacher adds “We will all be on the same page when teaching, rather than some classrooms concentrating on one topic for a long time when the others only spend a few days on it.”  The other teachers voice their agreement, and you thank each for invoking the two central goals of the meeting.  You ask the teachers to help you formulate a goal statement for this session, and after brief discussion it is decided.  You write ‘What factors should we, acting and teaching as a group, consider when deciding what content students will need to succeed in school and life?’ at the top of the dry erase board.  You ask the participants to keep this in mind during the session, and take a few minutes to review the steps of the process with the teachers, using the model on the itinerary as an aid.

 * Step 3: You ask everyone to take a piece of paper and a pencil for the next step.  Even though you have just explained the process, you review the actions that need to be taken during this step.  Keeping in mind that the teachers may require some additional guidance due to their relative inexperience using this decision making method, you use some of the criteria already established by the district board as an example.  You write ‘Readiness for School’ on the whiteboard and, as if thinking aloud to yourself, explain that this is an important criterion to consider because the lessons taught today become the foundation of lessons taught later on.  You write ‘State Test’ and think aloud about how students (and teachers) must cover some material if only because it has a significant presence in standardized testing.  Finally you write “Usefulness in Life” and think aloud how some topics may have a small presence on tests or later on in school, but have substantial significance or use in one’s life, such as learning basic economic principles.  You ask the participants to come up with at least four or five other criteria that they think should be considered during prioritization, reminding them to keep their list to themselves.

 * Step 4: After several quiet minutes you ask the participants to finish up, and then collect each list from each person yourself.  You explain that you will combine these lists into a consolidated list of all suggestions and that the participants may take a short break while you accomplish this.

 * The five sheets you obtain read as below:

 * You realize that the anonymity afforded by working individually will be worthless if you just wrote each list in total, one after another, on the board. Instead, you randomize the responses as best you can, crossing out each response as you write it on the board.  The result looks like the below:

 * What can we teach easily?
 * Are students interested?
 * Cost of ancillary materials
 * Student weaknesses
 * District’s past performance
 * How familiar are students with the topic already?
 * Cohesiveness with other standards
 * Interactivity
 * Greatest room to improve on CAT
 * Do we have any (more exciting) resources available besides the textbook?
 * Is it easy to teach?
 * Interest level
 * Time/effort needed to teach adequately
 * School needs
 * Student interest
 * School’s past performance
 * Available internet resources
 * What materials are available?
 * What do we need to raise social studies scores?
 * Time
 * Teacher interest
 * Alignment with school’s mission

 * Step 5: Once the teachers have returned from their break, you remind them that in this step of the process group discussion will be used to combine criteria that are essentially the same idea.  The first few are immediately called out and unanimously agreed upon. ‘What can we teach easily?’ and ‘Is it easy to teach’ are combined, as are ‘are students interested?’ and ‘student interest.’  Mindful of the difficulties that can arise later if the criteria are too general, you take the opportunity to ask the group exactly what “easy to teach” means.  They are silent for a moment until one teacher responds, “Well, to me it means that I don’t have to fight with the kids about it.  Something they like and will work at without me standing over them every second.” Another volunteers, “To me, easy means that I don’t have to do a lot of prep work.  If it’s a pre-planned lesson that I can tweak on the fly, that makes my job much easier.”  You point out that the criteria as it is currently phrased means different things to different people.  The first teacher points out, “True, and what each of us got out of it is represented by criteria that are also already on the board – ‘student interest’ and ‘what materials are available.’”  After some more discussion, the group elects to remove ‘easy to teach’ from the board, as it is too general, and can be represented by several other criteria listed.
 * After further consideration, consolidation, combination and elimination, the group agrees on the following consolidated list of criteria.

 * Availability of ancillary materials
 * School’s past performance
 * Cohesiveness with other standards
 * Teacher’s interest in topic
 * Students’ interest in topic
 * Time needed to teach thoroughly
 * Alignment with school’s mission
 * Students’ previous knowledge

 * Step 6: You ask the teachers to once again take a blank piece of paper.  You ask them to rank the consolidated list according to what they believe are the most important criteria for prioritizing state standards.  Remind them that they should keep their responses confidential and that they shouldn’t split hairs over their ranking, as they will have opportunity to change their minds later.

 * Step 7: After a few minutes you ask the participants to finish their ranking and gather the papers as before.  You offer them another break as you pore over the results, which are below:

 * You assign one point to each top ranking criteria, two to the second, and so on. You then add up the points awarded to each criteria. Finally, you arrange the results into a group-ranked master list, which lists the lowest scoring criteria first and the highest last.

{Try the calculations yourself before checking the results. How many points were recieved by 'Availability of ancillary materials?' { 20 }
 * type="{}"}

How many points were recieved by 'School’s past performance?' { 9 }

How many points were recieved by 'Cohesiveness with other standards?' { 38 }

How many points were recieved by 'Teacher’s interest in topic?' { 22 }

How many points were recieved by 'Students’ interest in topic?' { 8 }

How many points were recieved by 'Time needed to teach thoroughly?' { 22 }

How many points were recieved by 'Alignment with school’s mission?' { 37 }

How many points were recieved by 'Students’ previous knowledge?' { 24 }

/Show me the math used in step 7 and the group-ranked list that is the result/

 * Step 8: You transfer the group-ranked master list to the whiteboard for everyone to examine.  You open the discussion by asking the teachers if they see a low-ranked criterion that should be higher.  “I think the ancillary materials could be higher,” one participant ventures with some hesitation.  “If a topic has a lot of quality materials available, then we can give the kids a wider choice in what learning tools work best for them.  It would be a good way to reach out to more learning preferences and styles.”  Heads nod in agreement and another participant quickly volunteers “I think ‘teacher’s interest’ is way too high.  God knows some lessons are dull as dishwater for us, but its not really about us – it should be about the students.”  A few other points are made, but after a few minutes the discussion peters out and you take it as your cue to move on.

 * Step 9: You ask the teachers to take a piece of paper yet again.  You explain that they are going to rank the master list one more time, this time for keeps.  Assure them that they will have plenty of time to think and consider this time.

 * Step 10: Once all participants are finished, you collect their papers for the final time and once again sum their scores and arrange the criteria into a final group-ranked master list.  When finished, you notice that there is a strong break between the third ranked criterion and the fourth.  Realizing that this indicates a strong preference for the first three criteria, you announce that they will be carried over to the standards prioritization session, while the others must be discarded.

{Try the calculations yourself before checking the results. How many points were recieved by 'Availability of ancillary materials?' { 10 }
 * type="{}"}

How many points were recieved by 'School’s past performance?' { 12 }

How many points were recieved by 'Cohesiveness with other standards?' { 38 }

How many points were recieved by 'Teacher’s interest in topic?' { 28 }

How many points were recieved by 'Students’ interest in topic?' { 9 }

How many points were recieved by 'Time needed to teach thoroughly?' { 23 }

How many points were recieved by 'Alignment with school’s mission?' { 33 }

How many points were recieved by 'Students’ previous knowledge?' { 27 }

{Check the box next to the three criteria that will be used in the prioritization process. +Availability of ancillary materials? +School’s past performance? -Cohesiveness with other standards? -Teacher’s interest in topic? +Students’ interest in topic? -Time needed to teach thoroughly? -Alignment with school’s mission? -Students’ previous knowledge?
 * type="[]"}

/Show me the math used in step 10 and the final group-ranked list that is the result/

Using Results of Nominal Group Planning in a Decision Matrix
There are many possible methods for using criteria in a decision matrix to prioritize standards, ranging from simple grids to complex formulas and mathematically-determined weights. Because prioritization to external standards is almost always a group-based project, it is recommended that the simplest possible method should be used. This is so the manner in which prioritization decisions are made are transparent to all participants. If a complex statistical method is used, some participants may not trust that the results are representative of the “true” group consensus because they fail to understand the math. Such weighted calculations may be more accurate, but they do little good if some participants are not willing to accept them.

Steps for Conducting a group Decision Matrix

 * 1) Gather all decision makers if possible. Participants can submit their worksheets electronically or via post, but having all physically present reinforces the idea that this is a group project and results in a group consensus.
 * 2) Distribute a matrix worksheet, either on paper or electronically. The worksheet should already have any pre-existing criteria listed, along with the standards to be prioritized.  Blank columns should be available so that participants can fill in the criteria that were created during the nominal group planning session.
 * 3) Ask the participants to fill in the blank columns with the selected criteria.
 * 4) Explain that participants will evaluate each standard by each criterion in terms of importance, where ‘1’ means that teaching the standard is very important in meeting the criterion and ‘5’ means that it is of little or no importance.
 * 5) Allow participants time to fill in their matrices. Frequent breaks should be allowed so that participants do not “burn out” in the repetitive task of filing in the worksheet.  If the sheer number of cells required seems guaranteed to burn out participants (and return inaccurate scores) you will need to break the process into multiple sessions.
 * 6) Gather the finished worksheets. If the amount of data generated is extensive (i.e. it will take several hours to compute) it is advisable to adjourn the session and report the results at a later meeting.
 * 7) Sum the results for each standard across all of the criteria and all participants. For instance if you have three participants each using two standards (3 x 2), you will be adding six digits when calculating the score for each standard.
 * 8) Use the resulting score to classify each standard as high, medium, or low in importance. This is done by calculating the largest possible score for each standard and the lowest possible score.  All possible scores will fall in the range between these two numbers.  If a standard's score falls in the  lowest third of the range, it should be classified as high priority.  Scores that fall in the highest third of the number range are classified as low priority.  Standards that fall in the middle third are of medium priority.

Then What?

 * As has already been mentioned, this method values group consensus over statistic accuracy. This is in part because participant buy-in is an important factor, but also because small gradations in priority are difficult to put into practice in the real world.  Do you make a 90 minute lesson on a high-medium-high standard and 84 minutes on a high-medium-medium standard?  You could plan it that way, but any instructor can tell you that problems arise and the successful teacher is a flexible teacher.  The classification of high, medium, and low standards is not intended as input for an algorithm that will spit out the exact duration of a lesson.  Instead, it should be used as a general reference when planning instruction.

Narrative example of Using Results of Nominal Group Planning in a Decision Matrix.

 * Step 1. In the previous narrative example, the five social studies teachers have established three additional criteria:
 * Students’ interest in topic
 * Availability of ancillary materials
 * School’s past performance
 * You announce that the group will now move from defining criteria to actually using the criteria to prioritize the state standards.

 * Step 2. You pass out a worksheet that has eleven individual decision matrices, one for each major standard.  Above each matrix is printed the accompanying standard and its indicators (sub-standards).  In order to keep this example short, we will examine only one of these matrices.  The blank worksheet matrix appears below:

Step 3. You request that each participant fill in the recently generated criteria. The result is below.

 * Step 4. You explain to the participants that they will judge each standard by each criteria. For instance, if one feels that indicator 6.4.1 (Discuss the connections between geography and the development of city-states in the region of the Aegean Sea, including patterns of trade and commerce among Greek city-states and within the wider Mediterranean region) will be of utmost importance in later lessons or classes, then writing ‘1’ in the intersecting cell would be appropriate.  If one feels that 6.4.1 is of no use in later schooling, then a score of ‘5’ might be applied.

Each day for the next four days you email the teachers an Excel spreadsheet with two matrices and request that they fill it out and return it. Wary that some participants may save up their matrices to fill out at the last moment (and taking little care in their rush to complete it) you send a polite reminder when a teacher fails to return their file by the following evening.
 * Step 5. You realize that completing all eleven matrices requires filling in over a thousand cells.  You give the participants the option to complete them now, or to complete a portion of the sheet now, and finish at a later date.  The teachers, eager to complete this task vote to finish it in the current meeting.  You let them know that they are free to take a break at any time while completing the sheet.  However, within a half-hour you notice that most of the teachers are wearily rubbing their eyes and shifting uncomfortably in their seats.  You realize that the long day has taken its toll on the participants and would take its toll on the accuracy of their results as well.  You ask the teachers if they would reconsider finishing the scoring at a later time, provided it was done via email.  With some relief, they agree.  You collect the worksheets and find that all participants have completed up to at least standard 6.4.

 * Step 6. Finally on the fifth day you have collected all of the complete matrices. Below are the five matrices for standard 6.4

 * Step 7. You add the scores assigned to each criteria for each indicator by each participant.  You are secretly glad that the participants decided to turn in their later answers via excel, but still calculated the first four matrices by hand.

{ What scores did you calculate for each of standard 6.4’s indicators? 6.4.1 { 116 } 6.4.2 { 97 } 6.4.3 { 81 } 6.4.4 { 69 }
 * type="{}"}

/Show me the math used when scoring each indicator/

 * Step 7 You establish the range of possible scores by finding the highest and the lowest possible scores.

{ What is the... ...highest possible score? { 30 } ...lowest possible score? { 150 }
 * type="{}"}

/Show me how find the highest and lowest possible scores/

Once you've established the range of possible scores, you divide the range into thirds, rounding when necessary. { What is the score range that is considered... high priority? { 30 | 69 } to { 30 | 69 } medium priority? { 70 | 110 } to { 70 | 110 } low priority? { 111 | 150 } to { 111 | 150 }
 * type="{}"}

/Show me how the range of high, medium, and low priority is established./

You categorize standards that fall in the lowest-scoring third as high priority, the middle third as medium priority, and the highest third as low priority.

{What class of priority is indicator 6.4.1? - High - Medium + Low
 * type=""}

{What class of priority is indicator 6.4.2? - High + Medium - Low
 * type=""}

{What class of priority is indicator 6.4.3? - High + Medium - Low
 * type=""}

{What class of priority is indicator 6.4.4? + High - Medium - Low
 * type=""}

Now What?

You report the results of the prioritization session to the decision makers. You tell them what they largely already know - that these classifications of standards as high, medium, and low priority are intended to be guidelines for their upcoming content planning sessions, and while they should definitely be referenced during that process, slavish adherence to the classifications will be detrimental to the planning, and morale on the whole.


text:
Travel agency front and back office systems

Almost every travel agency in the world works with a Front Office or Back Office application and in many cases with a single tool that acts both as a Front and Back Office application for the travel agency. The Front part refers to the management and administration tasks and activities that are related to customer. The Back part refers mainly to the accounting related activities of the travel agency sales/purchasing figures.

Classification Categories
Most travel agencies work with a wide variety of decentralized applications. These applications' usages can be classified into the following categories.

 * A website normally considered as a gate way to the upside down
 * One or more GDS (Global Distribution Systems)which is used to handle online reservation/booking of mainly Hotel, Flight, Car products from different suppliers
 * A Front or Back Office application or a single application that acts as both Front and Back office application which in turn does the following:
 * Retrieve information from the GDS
 * Combine the information from the GDS with some extra information such as the customer details, passenger/traveller names etc.
 * From here, the system can create travel documents such as travel plans, invoices, credit notes and vouchers

Ideally a Front Office application, it ought to be able to communicate with the GDS and at the same time allow the creation and maintenance of the website as well.

Importance
A travel agency without a Front or Back Office application is most likely not able to do business effectively. It could easily be compared to two people writing a letter where one uses a type writer and the other uses a computer and a word processing application. With the amount of information handling required within a travel agency, and the tight competition between travel agencies within the local or global market, manual management and administration of these tasks is next to impossible without a tool that combines Front Office and Back Office tasks of a travel agency.

Back Office is the Back-bone of a Travel Agency which is equally important to the Front Office Operations. Travel agencies are working with a strict deadlines from IATA for its payments and other related things. For an IATA/SSI Agent, BSP (Billing and Settlement Plan) will be sending the statement of accounts for each fort-night three or four days after that fortnight. The agent has to make the payment to BSP on or before the 1st day of the next fortnight. If he failed to make the payment or make delay in paying three time in a calendar year, their access to issue the ticket will be revoked automatically. And this fortnight cycle will be continuing through-out the year.

So a very good back office system is a must for its survival


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Talk:Travel agency front and back office systems

* (cur) (last) 20:56, 15 January 2008 Vegaswikian (Talk | contribs) m (2,200 bytes) (→Importance: cat, past a stub) (undo) * (cur) (last) 02:02, 18 October 2007 Gonzo fan2007 (Talk | contribs) (2,234 bytes) (added sections) (undo) * (cur) (last) 07:50, 26 August 2007 Davewild (Talk | contribs) m (2,200 bytes) (categorised) (undo) * (cur) (last) 10:44, 20 August 2007 Fabrictramp (Talk | contribs) (2,191 bytes) (removing deadend tag; cleanup & maint tags as needed using AWB) (undo) * (cur) (last) 07:28, 18 August 2007 172.137.24.204 (Talk) (2,186 bytes) (undo) * (cur) (last) 03:30, 2 August 2007 Alaibot (Talk | contribs) m (2,188 bytes) (Robot: replacing with  on articles with stub categories) (undo) * (cur) (last) 04:52, 31 July 2007 172.130.4.105 (Talk) (2,184 bytes) (undo) * (cur) (last) 17:09, 30 July 2007 Egpetersen (Talk | contribs) (2,177 bytes) (undo) * (cur) (last) 22:14, 31 May 2007 Alaibot (Talk | contribs) m (2,070 bytes) (Robot: tagging uncategorised page) (undo) * (cur) (last) 05:53, 23 May 2007 Hloti (Talk | contribs) (2,037 bytes) (undo) * (cur) (last) 05:48, 23 May 2007 Hloti (Talk | contribs) (1,754 bytes) (undo) * (cur) (last) 05:37, 23 May 2007 Hloti (Talk | contribs) (1,723 bytes) (undo) * (cur) (last) 05:24, 23 May 2007 Hloti (Talk | contribs) (1,181 bytes) (undo) * (cur) (last) 05:19, 23 May 2007 Hloti (Talk | contribs) (1,117 bytes) (undo) * (cur) (last) 05:11, 23 May 2007 Hloti (Talk | contribs) (743 bytes) (←Created page with 'Almost every travel agency in the world works with a Front Office or Back Office application and in many cases with a single tool that acts both as a Front and Back...')
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Design for the Environment/Disposable Water Bottle

Introduction
Disposable Water Bottle has been a widely used commodity in the world. In the last decade, demand of water bottle has experienced significant increases, especially in the developed country such as United States. In 2006, the total global consumption of bottled water was 177.895 billion liters (47 billion gallons), a 61% increases from the 108.088 billions consumed in 2000. Out of the 177.895 billion liters consumed, United States led the world consumption by consuming 42 billion litters of bottled water (23% of total world consumption).

Due to this major consumption in United States; beginning in 2004, various organizations in the United States has been investigating the effects of water bottle to human life. These organizations mostly focus their analysis on the environmental effects, and health effects that the water bottle might cause. The results of these investigations have yielded several important environmental issues and health issues that should be considered widely.

Two major environmental issues that have been raised are solid waste generation and energy use. Water bottle manufacturers have been producing water bottles that are made of various recyclable but non biodegradable materials. If recycled properly, these water bottles will not cause any pollution to the environment. However in fact, not many of these bottles are actually recycled. In United States alone, 80% of water bottle consumed in 2006 ended in landfills, thus generating pollution by introducing solid wastes that are not degradable by the soil.

The energies that are used to produce water bottles are also enormous. According to Pacific Institute, 17 million barrels of oil are used per year to produce the water bottles that are consumed in United States. Combining the energy needed to process and transport the bottles, the number rises up to 50 million barrels of oil.

Polyethylene Terephthalate (PET) is the most popular material used for manufacturing plastic bottles and containers in the world. For, example, US plastic container demand is expected to exceed 200 billion units in 2010, consuming nearly 15 billion pounds of plastic resins. PET is commonly implemented for Water bottle because it has good chemical stability, and also a good barrier for moisture and gas. PET water bottle is commonly manufactured through injection moldingand extrusionprocess.

Glassalso has been used lately as an alternative for PET water bottle. Glass is used as the alternative because it provides good chemical stability, transparent, and most importantly, reduce general pollution level. Glass water bottle is manufactured thorough blow moldingprocess. However, care during the manufacturing process are intensively required due to the brittleness of glass.

The latest alternative for Disposable Water Bottle is PLA water bottle.PLA is a new kind of polymer fully synthesized of natural renewable sources such as corn, sugar cane, beet, wheat, and cassava providing the natural sugar as the main source of PLA. Thus, it makes PLA sounds very potential to most people in competing with existing petroleum based polymers especially in food and beverage packaging due to its biodegradability. In 1988 the research on PLA as a new polymer synthesized from Lactic Acid was conducted and in 2001 the demand for lactic acid in market, dominated by food and beverage packaging, was as high as 86,000 ton.

Project Information
Section 2 Group 8 Jonathan Juandi Wing Cheong Lee Louis Muliadi Hans Sutandie

Functional Analysis
As the baseline technology, PET has been the most commonly used material for water bottle production. The manufacturing process required for the PET production is considerably simple compared with the manufacturing process of the other two alternatives. However, among the 3 alternatives, PET water bottle produces most pollution.

In 2001, PLA water bottle merged to the market as an alternative material for water bottle production. In overall, PLA water bottle produce less pollution compared to the other two alternatives. However, lack of researches and development for the PLA technology hold backs its potential for commercial use.

Glass water bottle has been commercially used in the market as an alternative for PET water bottle; glass water bottle has major advantages over the other two alternatives in terms of its reusability. Aside from its outstanding reusability, glass has a major disadvantage in terms of its manufacturability. Compared with other alternatives, the manufacturing process for glass requires more care. Thus produces more cost.

Streamlined LCA
In the Premanufacturing stage, glass is considered to be the best alternative for disposable water bottle application. Although virgin materials are used during this stage, glass premanufacturing process produces least residue compared to the other 2 alternatives. Compared with other two alternatives, glass manufacturing requires more complicated and tight controlled process thus requires more energy consumption. Therefore for the manufacturing stage, glass is considered as the worst alternative compared with PET and PLA. Similar to the manufacturing stage, glass is considered to be the worst alternative for the product delivery stage. Glass has the highest density compared with the other 2 alternatives, thus requires most energy during product delivery stage compared with PET and PLA. Glass is the most favorable alternative for the End of Life stage, because glass requires least energy for recycling. Moreover, glass is very reusable compared with the other two alternatives. Therefore, creates less environmental impact. In overall, Glass is considered to be the best solution compared to PLA and PET.

EIOLCA
According to EIOLCA, glass water bottle production causes more environmental impact compared with PET and PLA. Glass water bottle production creates more air pollution, emits more green house gases, and requires more energy compared to PET and PLA. However, glass water bottle production releases less toxic materials compared to PET and PLA.Therefore, it can be concluded that from the EIOLCA comparison between the 3 alternatives that, PET and PLA are the best solution to be used as the material for water bottle.

Cost Analysis
Glass water bottle costs the most compared to PET and PLA water bottle. High cost in glass water bottle sector is caused by high manufacturing cost and high transportation cost. Although, glass water bottle costs the most, the difference in the cost between glass and PLA isn't significant.

Recommendation
From the 4 stage analysis, quantitatively PLA is considered to be the best alternative for the disposable water bottle industry. However, this alternative is not feasible at this point due to lack of information about PLA water bottle processing (eg. Recycling issue of PLA plastic) Due to this holdback, Glass water bottle, which is the 2nd best alternative in overall, is concluded as the best design for today’s condition.

Functional Analysis
PET, glass and PLA have several advantages and disadvantages that meets our basic function which is a resealable portable water container that is transparent.

PolyEthylene Terephthalate (PET)Water Bottle
PET bottle have excellent transparency and are extremely lightweight due to the low density. The processing of PET bottle is a lot easier due to good flow when molded allowing high speed manufacturing. It is strong enough for the water container application because it can withstand high internal pressure (5 to 6 bars) while also scratch resistant. As a side note, it is easy to design PET bottle because of the material flexibility and moldabilitiy.

Glass Water Bottle
Glass bottle have excellent chemical stability and good transparency. Design of glass container is rather challenging after considering its brittleness due to its heavy density therefore weight optimization has to be approached with more caution. Manufacturing method of the glass also has to be tightly controlled to ensure little porosity or to ensure minimal internal stress. To the eyes of the consumer however, glass is perceived to be a premium material, which although is heavier but is firmer and not flimsy. Glass also has outstanding reusability (if the consumer chooses to reuse) of 20 times before health hazard surfaces

PolyLacticAcid (PLA) Water Bottle
PLA is a new kind of polymer fully synthesized of natural renewable sources such as corn, sugar cane, beet, wheat, and cassava providing the natural sugar as the main source of PLA. This can divert our dependancy on petroleum based plstics hence preserving non renewable sources. From consumers’ perspective, PLA based material is promising in which they posses good properties such as low flammability, high resistance to UV light, lower specific gravity (lighter than other conventional plastics). Despite its advantage of using natural resources thus being environmental friendly, growing corn itself imposes environmental damage coming from the excessive use of pesticides and fertilizers

Background
Economic Input-Output Life Cycle Analysis (EIOLCA) model estimates the overall potential environmental impacts over the life cycle/supply chain (pre-manufacturing, manufacturing and operating stage) in the United States with an easier and faster way. The model is US 1997 Industry Benchmark and the economic activity uses $ 1 Million Dollars that means how many dollars of output are required to be produced.

Due to focus on potential environmental impacts of PETbottle manufacturing over the life cycle, options in the category including Conventional Air Pollutants, Greenhouse Gases, Energy and Toxic Releases are chosen to gather desired information.

CO
The highest amount of air pollutant is carbon monoxide (CO) and the main reason is ‘Truck transportation’. Therefore, truck transportation is the first objective to be improved in order to reduce environmental impact.

SO2 and NOx
Life cycle of glass bottle manufacturing causes significantly high Nitrogen Oxides (NOx) emission which 68.64% produces by glass bottle manufacturing. The reason is that glass manufacturing consumes much more natural gas for fuel (Shown in ‘Energy’ section below). The NOx emission of burning natural gas is much higher than burning Oil . In addition, the main source of SO2 emission is ‘Power generation and supply’ (Shown in the table below) and there is no significant difference in SO2 emission between PET, Glassand PLA.

In contrast, PETand PLAare best choice to be the bottle material in 'Conventional Air Pollutants' section because those manufacturing releases the lowest release of air pollutants.

Green House Gases

The values shown in the chart above are the sum of major greenhouse gases which include carbon dioxide (CO2), methane(CH4), nitrogen dioxide (N2O) and Chlorofluorocarbons(CFCs). This is no significant difference in Life Cycle Processes of PET, Glassand PLAbut it is obvious that glass manufacturing releases almost 14 times amount of greenhouse gases contrasting with plastic manufacturing process. The glassmanufacturing process consumes much more natural gas than plastic and this causes the amount of greenhouse gases is very large. Alternatively, 90% of the hydrocarbon emissions from natural gas are unburned methane, considered to be non-reactive in the formation of ozone in the atmosphere and causes large difference in amount.

On the other hand, the greenhouse gases emission of PLAin other life cycle processes is more than PET. Energy used in greenhouse gases emission of PETis less than PLAbecause producing PETresins consumes more energy than grain farming (Shown in the table below).

Therefore, glass manufacturing which releases much more greenhouse gases shows that glass is the worst choice of the bottle material in ‘Greenhouse Gases’ section and PETis slightly better than PLAby comparing the total greenhouse gases emission in the whole life cycle.

Energy
Rather than considering the output stages in life cycle, input information is also important for further analysis. The data of input is simplified in term of energy and shown in ‘Energy’ section in EIOLCA. The chart above has listed out the total energy used to manufacture water bottle by using PET, Glassand PLAin whole life cycle and three major energy sources (Electricity, Coal and Natural gas). In general, glassbottle manufacturing consumes more energy due to much more energy input in glassmanufacturing process. The main consumer of Coal is power generation and supply which obtains about 90% of the usage of Coal (Shown in the table below). Also, glassmanufacturing consumes much more natural gas than plastic manufacturing. Therefore, PLAbottle manufacturing uses the least energy and is the best choice in ‘Energy’ section.

Toxic Releases

After comparing the Toxic Releases Tables of PETand Glass(Shown in the table below), ‘Copper, nickel, lead, and zinc mining’ is the major source of toxic releases in both PETand glassbottle manufacturing including high concentrations of some chemical elements, notably arsenic and sulfuric acid. On the other hand, ‘Plastics material and resin manufacturing’ is the second main source of larger toxic releases. Consequently, more the toxic substance produced and releases in water because of mining, more the toxic substance transferred to Publicly Owned Treatment Works (POTW) which is focused on end-of-pipe solutions to remove wastewater pollutants. Therefore, glassis the best choice of bottle material in ‘Toxic Release’ section.

Streamlined Life Cycle Analysis
Background

Streamlined analysis provides a very fast means to analyze a certain product throughout its life stages. This tool is especially good and useful in conditions where data availability, expense and time are strictly limited.

Below, three streamlined life cycle analyses (SLCA) are presented for bottles made of PET, Glass, and PLA. The analyses are conducted throughout 5 life stages: pre-manufacturing or resource extraction, manufacturing of the bottles, product delivery, product use, and end of life (disposal, recycle, or landfill). Each life stage is evaluated in material choice, energy use, solid residue, liquid residue, and gaseous residue. Each cell of matrix will be assigned a value ranging from 0 (lowest) to 4 (highest) depending on the impact of each component on the environment. Finally, the sum of the scores is calculated and compared to the maximum value (100) to judge the quality of each life cycle.

PolyEthylene Terephthalate (PET) Water Bottle
Pre-Manufacturing The lowest score of SLCA of PET lies in this life stage since PET is a petroleum base plastic the main resources of which is non-renewable fossil energy. Furthermore, during this pre-manufacturing stage the amount of residues that are solid, liquid, and gaseous residues is the highest compared with the remaining life stages.

Manufacturing The main concern in this life stage is the gaseous residues produced from the plant. Other disadvantage is the relatively high amount of energy used generally in the melting process of the resin and in injection of the resin to the mold afterward since high pressure is needed. However, the solid and liquid residues are minimal.

Product Delivery Since PET is light, the transportation for product delivery is flexible and due to its light weight energy consumption is reduced. However, solid residue (landfill) due to the disposals of truck tires is abundant and gaseous emission from the vehicles combustion is unavoidable.

Product Use Thanks to lightweight PET, PET based bottles are easy to carry and furthermore they produce no solid, liquid and gas residues during their use.

End of Life Ninety nine percents (99%) of PET bottles are recyclable in the respective recycling facilities with low energy consumption, solid and liquid residues. However, the gas residue from the transportation to the recycling facility is inescapable thus making it the main concern in this life stage.

Glass Water Bottle
Pre-Manufacturing During this life stage, the main concern is the energy used to transport the raw material to the manufacturing plant. There is only little solid residue mainly from truck or train bodies as the transporting vehicles which can be quickly reused. In addition, raw material transportations also cause gaseous residue.

Manufacturing the main concern during the manufacture is the extremely high energy input 24/7 needed to melt the raw material. Although, there is only little solid and minimal gaseous residue, water contamination occurs here contributing another concern.

Product Delivery During the transportation the energy use is very high due to the heavy weight of glass and packaging materials (e.g. boxes) required to compensate for their fragility. Solid residue is of little concern since boxes for example, in particular, are highly recyclable. However, transportations always produce Global Warning Potential (GWP) gas emissions.

Product Use This life stage scores the highest due to the high reusability and rigidness as well as good appearance that is commonly favoured by consumers. Also, there is no residue at all during the use phase.

End of Life Since glass bottles are highly recyclable there is very little concern of solid waste. Moreover, in this life stage, liquid and gaseous waste is negligible. Nevertheless, high energy input is required for the recycling process such as proper cleaning and treatment for the bottles.

PolyLacticAcid (PLA) Water Bottle
Pre-Manufacturing The material choice is given the highest score since the resource of PLA is 100% natural and renewable thus the process involves chemical reactions producing abundant liquid residue . During the material extraction, energy use is mainly from coal and natural gas (corn farming) reducing the use of the less abundant oil . Furthermore, the fossil energy input is 50 – 68% lower than that of conventional plastics . Gaseous emission is of interest since in corn farming, CO2 is used for photosynthesis thus helps decrease CO2 concentration in atmosphere. However, the use of excessive pesticides and fertilizers would cause harms to the environment .

Manufacturing The manufacturing of PLA bottles are similar to that of PET since both use the same fabrication methods thus since PLA has lower melting point than PET energy use is reduced but still high amount of energy is required as additional processes such as drying and perform making are needed before resin is injected to the injection molding machine The material used is not completely closed loop but does not involve any restricted material. Also there are no liquid and gaseous residues yet there may be solid residue.

Product Delivery The transportation vehicles not only emit gaseous residues such as CO and CO2 but also needs abundant fossil fuel input. However, the packaging material which is most commonly cardboard can be recycled which in turn reduces solid waste.

Product Use In terms of product use, there is nothing in a PLA bottle that can cause any harm to the environment and there is no energy used as well as any residues at all during its use.

End of Life All PLA bottles are biodegradable but not self biodegradable thus all the bottle must be processed in a composting facility where the temperature must be kept at 1400F for a certain period and this requires high energy use . Also, degradation process produces high amount of gaseous (e.g. CO2) and liquid residues (e.g. water).

Economic Analysis
Cost of siding with specific alternative must be considered when selecting the best water bottle design for the environment. In order to make useful and non convoluted analysis, assumptions were made to simplify the cost analysis:

 * 1) Manufacturing plants (for the alternative analyzed) are already in existence and ready to use
 * 2) Capital cost required to implement the alternatives are neglected
 * 3) Transportation costs are neglected
 * 4) The costs are calculated in 1997 USD

The first assumption takes advantage of the fact that current existing manufacturing facilities (for respective materials) can be utilized to produce the water bottle containers. The second assumption is possible because the alternative is expected to be in production for long period, hence capital costs will be minuscule compared to the long term (annual) costs. Transportation are energy and cost intensive but it is neglected because it requires logistics and geological consideration that is beyond the scope of this analysis.

The assumption taken can admittedly boast the image of the certain alternatives. If transportation costs are included, glass implementation costs will likely increase because the heaviness of glass would imply higher transportation cost. Similarly, cost for implementing PLA could be significantly higher due to the capital costs required to implement novel material, not to mention extended research fundings needed.

Please note that indirect costs are excluded because of the lengthy information that is beyond the scope of this analysis.

PolyEthylene Terephthalate (PET)Water Bottle
Energy Cost PET bottle manufacturing primarily uses blow molding technique. A highly mechanized PET bottle manufacturing could turn a molten plastic into a bottle shaped plastic within 12 seconds, which is equal to 300 PET bottles within an hour (assume nonparallel operation). Therefore 12,800,000 cycles are needed to manufacture 3.84 billion bottles in 1997. One injection machine and one blow molding machine are used to manufacture the PET bottles. Each machine consumes 19kWh = (12,800,000)*(38kWh) = 486 x 10^6kWh and the total energy cost is ($0.05 per kWh)*(486 x 10^6kWh) = 24.3 million

Materials Cost The price of PET resin is 0.947$/kg. Assume weight of PET container is 10 grams (3,840,000,000)*(US$0.947)*(10 gram per bottle) = 36.4 million

Labor Cost Knowing that cost of operating injection and blow molding is $60/hr including labor cost, we assume that our injection molding (with 20 cavities) and blow molding average time will still be 12s to manufacture one PET bottle. Therefore, one hour can produce 6000 PET bottles which equates to 640,000 hours of manufacturing and hence the cost for labor is 76.87 million

In total, it will cost roughly 137.57 million dollars to produce the PET bottles annually.

Glass Water Bottle
For safety purpose, we choose to manufacture glass bottle that is of transparent non colored shape similar to PET bottle volume. The estimated weight is 250 grams which will ensure some rigidity and allow some safety factor before crack develops.

Energy Cost Assume that for the energy consumed we are burning natural gas. If 1 ton of glass production liberates roughly 700kg of CO2 then we can assume that 255kg worth of methane is being used as the fuel to heat up the glass raw material. Given price of $7 per gigajoule we can assume that to make 1 ton of glass we will require $7 x 255kg / 0.717 x 39 Mjoule = $97 worth of natural gas Using similar bottle numbers as PET, one will require 3,840,000,000 glass which equates to 93 million dollars worth of money being used on energy alone

Materials Cost Now consider that glass is composed of 70% sand and 9% soda ash with the remaining 21% being colorant and smaller particulate. In this analysis, we neglect the remaining 21% because we stated no colorant and the small particulate is really little hence not adding to significant economic value compared to sand and soda ash. Therefore, we say 87% of the bottle mass is sand and 11% of the mass is soda ash. For production of all bottles annually, we need 3.84 billion bottles x 217.5 g = 0.84 million ton of sand, which costs 17.54 million dollars. Similarly for soda ash we require 0.125 million ton of soda ash, which costs 4.37 million dollars.

Labor Cost Similar to PET bottles.knowing that cost of running ,blow molding, annealing is $70/hr including labor cost, we assume that our glass cutter (capable of generating 10 gobs per cut) and blow molding average time will still be 15s to manufacture one glass bottle. Therefore, one hour can produce 2400 glass bottles which equates to 1,600,000 hours of manufacturing and hence the cost for labor is 112 million

In total, it will cost roughly 227 million dollars to produce the Glass bottles annually.

PolyLacticAcid (PLA) Water Bottle
It is assumed that the PLA economic activity would be dominated by Cargill Dow (NatureWorksTM) and the number of PLA production and sales would be based on their established information.

Energy Cost Similar to PET manufacturing, PLA uses injection and blow molding that is highly mechanized in order to reduce downtime. A highly mechanized PET bottle manufacturing could turn a molten plastic into a bottle shaped plastic within 12 seconds, which is equal to 300 PLA bottles within an hour (assume nonparallel operation).Therefore 12,800,000 cycles are needed to manufacture 3.84 billion bottles in 1997. One injection machine and one blow molding machine are used to manufacture the PET bottles. Each machine consumes 19kWh = (12,800,000)*(38kWh) = 486 x 10^6kWh and the total energy cost is ($0.05 per kWh)*(486 x 10^6kWh) = 24.3 million dollars

Materials Cost Assume that price of PLA is $2.3 per kg in 1997. If the weight of each bottle is 9 grams, then to satisfy 3.84 billion bottles we will require 79.49 million dollars on raw material.

Labor Cost Knowing that cost of operating injection and blow molding is $60/hr including labor cost, we assume that our injection molding (with 20 cavities) and blow molding average time will still be 12s to manufacture one PET bottle. Therefore, one hour can produce 6000 PET bottles which equates to 640,000 hours of manufacturing and hence the cost for labor is 76.87 million

In total, it will cost roughly 180.66 million dollars to produce the PLA bottles annually.


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Free machining

Free machining is a manufacturing process utilizing steel, which has specially been designed to increase the machinability of a material during machining.

What is machinability?
Machinability is a property of a material that is usually defined by four factors. These factors include (1) surface finish and integrity of the machined part, (2) obtained tool life or tool wear, (3) the magnitude of force and power required, and (4) ease of chip (excess material) production. Commonly this is achieved by alloying the material with sulfur or lead.

Leaded steels
Free machining steels are commonly produced by adding lead to molten steel in order to serve as a solid lubricant during the machining process. The process of free machining increases the machinability of the steels and consequently reduces the costs incurred by steel producers. The lubricating effect of lead is due to the lead particles shearing (breaking) off and building up on the chip-tool interface (contact point). As the tool machines the steel, the built up lead flows under the tool and along the leaded steel. Since lead has a low shear stress, it reduces the friction between the tool and the metal. As a result, the tool slides along the lead particles more efficiently. It is believed that the magnitudes of forces and power required to machine the steel is further reduced by the presence of lead in steel. This occurs due to the lead reducing the shear stress in the primary shear zone (focused area of machining). Leaded steels are are still the major type of free machining steels used today, inspite of lead's toxicity. Attempts to substitute other non-toxic metals with similar properties, such as bismuth and tin, have to-date met with only limited success in the steel industry.

Resulfurized and rephosphorized steels
Adding sulfur to steels results in raised stresses within the primary shear zone of the steel. During machining, the chips that are produced are small and easily break up, increasing tool life and also increasing the ease of chip production. From this, the machinability of the material increases in the same manner as leaded steels; the cutting force and power required to complete the process are reduced.

title: Free machining


text:
Talk:Free machining

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title: Talk:Free machining