Anne-Marie M Jolly
email: anne-marie.jolly@univ-orleans.fr

C Leger

G Lamarque

"Smart building": a new concept of engineering education curriculum

Keywords: smart building, energetic efficiency, home automation, sensors, networks

In the close future, our society and its engineers will have to find solutions for a better management of energy; it can be realized through: the increase of isolation of building with eco-materials, the use of renewable sources of energy, the increase of communication between energetic devices placed inside this building but also with energy production plants more fitted and the increase of the number of inside and outside sensors

In the same time, the disaffection of students for electrical engineering led us to define new courses based on concepts linked to electronics, electrical networks, and sensors. We saw that electronics applied to energetic efficiency and home automation could attract students whose current interest lies much more in civil engineering or sustainable development.

The teachers of all engineering department designed the course together, taking in account necessary learning outcomes.

The idea of a course leading to jobs such as integrator of solutions for energetic efficiency of buildings or designer of systems for smart homes, revealed to be fitted as well with the needs of companies (Schneider, Atlantic-Thermor, Legrand…) as with the interest of young people.

Introduction

Classical engineering courses, defined by their theoretic fields of teaching: civil engineering, electronic engineering, material engineering, thermal engineering, are of classical use in French universities of engineering. New problematic such as those created by energy lack create needs of skills that are not defined in reference to these traditional disciplines; however, a generalist engineer is not the best solution because some of the skills involved in these new jobs are quite specialised. Hence the idea to develop multidisciplinary courses better fitted to new jobs.

The problem of attractivity of engineering

Polytech Orléans [1] is one of the 12 schools of engineers of the Polytech network. In these schools of engineers, it is possible to study in classical fields of engineering: civil engineering, electronic engineering, material engineering....because these schools are parts of universities where laboratories in their fields of engineering exist.

Since 15 years convincing young people to make studies leading to a job of engineer is not easy. Many factors [START_REF] Becker | Why don't young people want to become engineers? Rational reasons for disappointing decisions[END_REF] interfere in this situation but the lack of interest for electronic engineering studies reached in 2008, in our school, a point where it was necessary to realise a strong brainstorming, leading to new courses but also to a new marketing of these studies. The students have difficulties to imagine that many things that make their life easy and pleasant (videogames, phones..) have been designed by electronics engineers; moreover the interest of young scientist is very oriented towards sustainable development and pupils don't always make a positive link between technologies and environment. At the same moment there is a strong need for young scientists in the fields of electronics and automation to develop tomorrow life [START_REF]Engineering: issues, challenges and opportunities for development[END_REF].

So we made an attempt to find an idea of a name of course that could interest pupils and that the teachers of the school would be able to teach too! We organised, for pupils, tombola were it was possible to win a game console if they class name of courses, related to electronics, according their preference; the concept of smart building earned the plebiscite of the potential students.

Project like Helena [START_REF]Egalité des chances dans les études et la profession d'ingénieur en Europe[END_REF] attempts to show that girls in engineering are most attracted towards multidisciplinary engineering studies. It is the case in our school for civil engineering which is in the same department as environment. In the case of smart building which is a mix of electronics, materials and civil engineering, it should be the same thing.

Combining electronic matters with environment matters leads to a course were students feel themselves useful; this new course should really be attractive for young people, very concerned about sustainable development: indeed, because they see the aim of what they learn, even if they have to study questions related to electronics, they can bear it! Enterprises that need those skills helped us to show to pupils how interesting these studies are. In the first year (September 2010) of the application of the new name of the course: eco-technology in electronics and optics option smart building, the number of students increased immediately.

Requirements for this course

Global requirements

According to the action plan of European Community concerning energetic efficiency, European Union must reduce of 20% (with respect to the level of 1990) the emissions of greenhouse gas, reduce of 20% the electric consumption, increase of 20% the part of renewable energies in the total consumption of energy.

In France buildings use 43% of the total energy and transports use 31% of it. The buildings constructed before 1975 use more than 450kW/m2, buildings constructed since that date without particular application of norms between 150 and 250 KWh/m2 and buildings constructed in respect of norm RT 2005 between 50 and 100kWh/m2.

We see on these figures that it is still too much, so the next steps necessary to satisfy requirement of EU are: Low Consumption Building (50kWh/m2) but even more passive building (<15 kWh/m2) and especially Positive Energy Buildings.

In the house 33% of the energetic use of families is done by the electric devices: for these devices, it is necessary not only to consume less energy when they are used, but also when they are in vigil, 14% of electric use inside the house is the fact of lighting; if there is a good automated management of all these devices, a strong reduction of the consumption can be expected. Concerning electric heating, decrease of the temperature of 1 degree during 24 hours reduces the electricity use of 7%.

A better isolation and a better design of design is not enough to fulfil requirements of EU, it is necessary to make building become "intelligent"

Enterprises needs

The analysis of the needs of enterprises concerning recruitment of engineers in the sector of the technical building management showed that electrical engineers and computerscience or automation engineers only partially meet the needs of professionals. Engineers at consulting firms are able to design an acquisition chain (sensor and conditioner) and the processing (scanning and signal processing) of a quantity related to this technical building management (temperature, degree of humidity, light level...); moreover, they are able to develop multi-sensor architectures that can exchange information using various existing communication media (wired, optical, wireless...). But, their lack of knowledge of the standards relating to building, of the main features of the different materials used in building, and of the thermal aspect of the building does not allow them to offer optimal solutions. At the extreme, the system designed can be totally ineffective when installed in a building, because this ignorance of thermal-energy aspects of the building does not allow them to take into account all the constraints in designing such a system.

Our smart building course aims to train R & D engineers with strong skills in electronics and computer-automation science, able to understand, analyze and take into account all constraints related to building and the environment in which it is located. These field engineers, with a dual skill electronic-automation and computer from one side and energy and thermal of the building on the other part, will be powerful actors in establishing relevant specifications relating to the introduction of intelligent systems in and around the building (e.g. : fire protection, thermal regulation, management of openings, lighting, taking into account different energies, application of labels). Smart building engineers will be able to analyze the problem and find innovative solutions in comfort (technical management of buildings, multimedia...), home support (disabled, elderly), both in new buildings and renovation after an audit of existing buildings, for individual or collective, in manufacturing and services.

The transversality of their field of expertise will enable these engineers to be more effective in innovation, in fact, this will be quite necessary because these engineers will be the pioneers in their field. To ensure the continuity of this double competence at all levels of the building industry, these engineers will have to train both integrators and installers but also their own employees.

Concepts covered by our Smart building course

Fig1 Smart Building according to Electric Power Research Institute

The concepts cover large fields because tomorrow house will be seen as a global entity, moreover the problems attached aren't limited to those of energetic efficiency but they enlarge to care or safety [START_REF] Sinopoli | Smart buildings: a handbook for the design and operation of building technology systems[END_REF], [START_REF] Wang | Intelligent buildings and building automation[END_REF]:

-management of the building so as to make it more efficient: new sources of energy, stocking of energy, thermal comfort integrating all the sources of energy, water, quality of air -management of all the channels of information inside the building (voice, data, images) -caring of people at home -security of buildings and persons at home -link with smart grids It is important consider all these points as a part of a more global solution if the engineer has to propose solutions that can evolve.

Method

To go through such a transverse project, methodology of brainstorming and team efficiency is necessary. The first step was to mix teachers and researchers in electronics, renewable energy, materials and mechanics, heat energy, networks, automation…. They discussed about the skills necessary for jobs related to those fields:

-Technical management of buildings -Design of electric or electronic devices for building -Management of energy inside buildings -Eco-design of buildings

The idea for everybody was to be able to form an engineer with good scientific bases able to adapt to the technological evolutions and to imagine innovative solutions.

This work was very interesting for the participants because usually, courses like civil engineering, electronics and optics, energetic and materials don't interfere. For that reason, teachers are not used to design a course mixing knowledge from the different fields.

The curriculum

The content

All French engineers have basic knowledge in mathematics, computer science and management of project, but in this particular course, 3 great areas have been considered as the heart of the teaching:

-Management of energetic needs -Management of people and assets -Habitat and environment The first item includes energetic optimization, ecodesign, renewable energy, management and optimization of energetic needs, home automation and electric devices for home comfort.

The second one is related to sensors, communication networks, interoperability, multimedia, video surveillance, safety, caring people at home

The third one concerns waste and water treatment, environmental norms about buildings, Electromagnetic compatibility.

Those points are then declined according basic teaching areas: electronics, automation, computer science, mechanics and materials, energetic, heat energy.

It results in the final course that about 2/3 of the teachings concern the points of view of the IEEE engineer and 1/3 the point of view of the building engineer. As the university is situated close to a school of art and design, common projects between the engineers in smart building and student from the art department will take place to give more interest to the projects of both students. This will also increase acceptability by inhabitants of solutions for home automation.

In France the studies to become engineer last 5 years after A-level. Our course correspond to the 3 last years, it has an academic duration of 1800 hours. It addresses to student having a scientific diploma general or specialised, in this way, we respect CTI 's recommendations [START_REF]Références et Orientations CTI[END_REF], the French engineering agency for the accreditation of engineering curricula.

The first year gives the students strong skills in mathematics, automation, computer science and thermal. These skills will allow them to understand the more specific courses of the last two years, but will also give them opportunities to reorient their career after some years if they want to.

We will give details of the last two years corresponding to the Masters 'Degree. During the last year of this master degree student will make a trainee in enterprise, it is the reason why the number of hours of lecture, tutorial and practical work is reduced. There are many small projects included in each of the thematic courses, this is necessary, because we want that the students really become implied in each part of the curriculum and not only consumers of the course.

Other approaches

As we explained previously, the specificity of our course is to give dual competences very interconnected: there is a strong part of engineering education in the field of electronics and computer industries and other engineering courses in the field of civil engineering.

To address concerns about the Grenelle environment, new engineering programs have emerged as for example Intelligent Building in Polytech'Nice. This training, close to the civil engineering, is very different our course in Smart Building.

Other approaches of new courses based on civil engineering oriented towards smart buildings concepts are in development in other engineering universities. Both engineers, from civil engineering and from the new curriculum are necessary and will have to work together. Our choice to develop the course from electronics is linked to the skills of a great number of teachers-researchers of our university, making researches on smart grids, intelligent electric networks or data fusion for smart building but also to the proximity of a cluster of enterprises (S2E2) very active in those fields.

Conclusion

Once the course designed, we presented it to the companies concerned to refine and validate it; they were satisfied because there was a real lack of engineers able to act as integrators. So they took time to defend and explain the course in front of the accreditation agency.

It is not evident, to defend the existence of this kind of multidisciplinary course: at this moment, accreditation agencies like CTI are looking for a standardisation of the engineering title of diploma to have greater facilities of exchanges of students at a European level.

But, it is interesting to note that in France in this moment the secondary technical school is being reformed: the government decided that instead of having a A-Level in electronics or civil engineering, it would be more interesting for the pupils and the enterprise to have a A Level whose new name is: STI2D "Sciences et Technologies de l' Industrie et du Développement Durable". In this new course, both concepts of Information, Energy and structures are linked. So we hope that this concept, which is similar to our concept of smart building, will show all its benefits in education and enterprise field.

We already consider that the result of our work is a course defined as useful and necessary by major companies and a project allowing a better knowledge of the domains of each other by the team of researchers-teachers of the engineering school. So opportunities for common research projects will certainly appear consequently.

The interest of potential students revealed immediately on the forum of presentation and in the frequentation of the school.

At a moment where innovation in engineering universities is a great debate, new course to make engineers able to find innovative technical solutions to the problems of energy and to make life in old and new buildings easier is something motivating for everybody.

.


Ahmad Almhdie
email: ahmad.almhdie@univ-orleans.fr

Christophe Léger
email: christophe.leger@univ-orleans.fr

Roger Lédée

Rachid Harba

Ahmad Almhdie-Imjabber

Conference on Systems, Signals and Image Processing Atlas-assisted Segmentation of Cerebral Structures of Mice

Keywords: Atlas registration, Chan-Vese segmentation, MRI cerebral images, Trisomy 21. I

come

INTRODUCTION

The motivation of the work presented in this paper is to understand better the morphological malformations of the brain associated to Trisomy 21 or Down syndrome. Characterization of morphological malformations associated to trisomic mouse models for particular chromosome segments will help to link genes from these segments to specific dysmorphologies. It would also help to look after the consequences of this disease, and to improve the quality of life of the patients.

Biologists are interested in the reconstruction of cerebellum surfaces to better understand the morphological malformations of the brain associated to Down syndrome.

In order to extract different cerebral structures, MRI images should be segmented. Since manual segmentation is difficult and computationally expensive, automatic methods have been proposed [START_REF] Gibou | A Fast Hybrid k-Means Level Set Algorithm for Segmentation[END_REF]. This problem can be solved using a variety of techniques. The Chan-Vese method is one of the most used techniques [START_REF] Chan | Active contours without edges[END_REF]. However, since the contrast between different objects in the brain is low, a semi automatic technique that considers information given by the user could be more efficient and less complicated to develop. A good review of current medical image segmentation methods can be found in [START_REF] Pham | Brain MRI Segmentation with Multiphase Minimal Partitioning: A Comparative Study[END_REF].

Most automatic segmentation methods are initialized by a contour that best describes the target object, i.e., circle or ellipse. However, the cerebellums and the hippocampus are difficult to segment due to their complicated shape. In addition, limits of these objects included in the brain are unclear Atlas data could be a good solution to initialize segmentation since it approaches better these internal cerebral structures. But due to different acquisition positions, the Atlas should commonly be registered to targeted object before it can be used. Variants of the Iterative Closest Point (ICP) algorithm have widely been used for the estimation of rigid transformation parameters of 3D closed surfaces. For instance, the Comprehensive ICP (CICP) algorithm has been proven to be robustness to Gaussian noise and efficiency in terms of precise estimation of registration parameters.

In this work, we present a complete procedure for the segmentation of cerebellum that includes an initialization step using a registered brain Atlas and a segmentation step using a modified Chan-Vese method. The reconstructed surfaces make it easier to study the characterization of morphological malformations associated to trisomic mouse models. As a first step, measured volumes are compared.

The next section gives a brief description of used Atlas. Section 3 presents the used registration technique, required prior to the use available Atlas. The use of a new variant of the well-known Chan-Vese method is then demonstrated in section 4. The results are then presented and discussed. Finally, conclusions are given.

II. ATLAS PRODUCTION

Three lines of mice carrying the trisomy of chromosome 21 as well as a normal line are provided by the IEM laboratory of the National Centre of Scientific Research in France (CNRS) as shown in Fig. 1.

High resolution three-dimensional (3D) Magnetic

Resonance Imaging (MRI) images of mouse models are realized at the CBM laboratory of CNRS, France. Several experiments were conducted to obtain images with high spatial resolution (118.288.5118.2 µm3/voxel) with many details of the neuro-architecture, thanks to the power of the magnetic field and imaging gradient available on the used imaging system, first of its kind in France. Fig. 2 shows a 3D image (110341110 voxels) as a result of one of these experiments. An atlas for each of the brain, cerebellum and hippocampus structures is obtained by manually tracing their contours on a sequence of corresponding coronal slices. This has been done by IEM experts. The pixels of the selected contours represent the 3D atlas data as presented in Fig. 3 for a normal cerebellum. One 3D MRI image from each line is selected as a reference.

III. CICP REGISTRATION ALGORITHM

The CICP algorithm is recently developed in our institution as a method of surface registration. Although More details on this variant of the well-known ICP algorithm can be found in [START_REF] Almhdie | 3D Registration Using a New Implementation of the ICP Algorithm Based on A Comprehensive Lookup Matrix: Application to Medical Imaging[END_REF], we recall its general functionality. Let us assume that the given two surfaces to be registered can be described as point sets; the scene data points, P, with Np points, {p i , i=1, …, N p }, and the reference data points, M, with Nm points, {m j , j=1, …, N m }. Depending upon the sampling of the surfaces, N p is not necessarily equal to Nm. Furthermore, the point p i of the scene surface does not necessarily represent exact 3D correspondence to the point mi of the reference surface. However, the search space is determined by the size of the scene data set; i.e., N p . The CICP algorithm can be summarized as follows:

A. Initialization  Let the initial scene surface P 0 , be equal to P.

 Define the maximum number of iterations k max .

 Initialize the translation vector and the rotation matrix as follows: Different close-form solution techniques of the original ICP algorithm can be used, i.e., quaternion [START_REF] Horn | Closed-form solution of absolute orientation using unit quaternions[END_REF][START_REF] Mukundan | Quaternions: From Classical Mechanics to Computer[END_REF] or single value decomposition [START_REF] Arun | Least-squares fitting of two 3-D point sets[END_REF]. The resulting transformation from the minimization of the above equation at step k will be denoted R k and T k . This step also provides the minimum distances which correspond to the matched pairs.

          
 Compute P = R k  P 0 + T k and restart a new iteration if the change in the MSE is above a predefined threshold , and if the maximum number of iterations k max is not reached. If not, stop the iterations and exit.

The high quality results of segmentation of the brain that we obtained using a Chan-Vese based method could be used to perform such a task. A possible strategy is described in the following for the segmentation of the cerebellum (it would be identical for the hippocampus).

We start from a reference brain and a reference cerebellum of a given mouse which are manually segmented. On the mouse under consideration, we first could use a rigid registration process (only translations, rotations and homothetic deformations are allowed).

The reference brain is first registered with the brain segmented using the semi automatic process presented in [START_REF] Almhdie | Chan-vese based method to segment mouse brain MRI images: Application to cerebral malformation analysis in trisomy 21[END_REF] (first line of Fig. 4). Using the CICP, the measured rigid transformation between the current brain and reference brain is then applied on the reference cerebellum (second line of Fig. 4). The resulting registered cerebellum is used for initializing the segmentation of the true cerebellum.

Before registration

After registration Figure 4. Reference data are presented in blue color, whereas segmented brain is in purple. Top of the figure, the reference brain is registered with the brain under consideration. Bottom of figure, the rigid registration is applied to the reference cerebellum. This will be the initialisation to the segmentation process

IV. RESULTS AND DISCUSSION

Once the atlas data is registered, our proposed Chan-Vese based segmentation method is applied. While preserving the advantages of level set methods, such as automatic handling of topological changes, the proposed method integrates region information to guide the evolution of the initial segmentation. By this way, the initial contour is very close to the objective structure, as show in Fig. 5b. In addition, using a level-set based active contour method will refine segmentation results while preserving object structure. In order to accelerate processing time, segmentation is limited to the presegmented brain region, since cerebellum is always found inside the brain.

Experimental results show that the proposed process works efficiently for most treated images, as seen in Fig 5c . However, it has occasionally some problems of detecting the barrier between brain and cerebellum, on which we are currently working by integrating 3D information to guide the segmentation process. More work has to be done on the choice of segmentation parameters that more suitable to our MRI images. V. CONCLUSION It is demonstrated in this paper that atlas data can help improving the segmentation precision of mouse cerebral structures and overcoming the common problem associated to the initialisation of the well-known Chan-Vese method. The quality of the registration-assisted segmentation process makes it possible for global and local comparison of internal cerebral structures that is of great interest to biologists to understand the characterisation of morphological malformations associated to trisomic mouse models.

Figure 1 .Figure 2 .

 12 Figure 1. Considered mouse brain models

Figure 3 .

 3 Figure 3. Considered mouse brain models

  coefficient of the translation vector and rotation matrix set as follows: t u =0, r u,v = 0 if u ≠ v, and r u,u = 1, u =1,2,3, v= 1,2,3. This corresponds to zero translation and no rotation.B. Iterations For each point p i P, (i = 1, ..., N p ), the algorithm computes the Euclidian distance d i,j to each point m j M, (j = 1, ..., N m ). Then, for N p times, the algorithm:o looks for the location (i,j) that corresponds to the minimum distance d i,j in the current look up matrix, o assigns p i to m j as a correspondence pair j , o removes this correspondence pair from future consideration. Using the selected correspondence pairs, compute the transformation, rotation (R) and translation (T), that minimizes the mean square error (MSE) of the estimated correspondence pairs:

  (a) Atlas Before registration (b) After registration using CICP registration algorithm (c) After refinement using a variant of Chan-Vese segmentation

Figure 5 .

 5 Figure 5. Atlas assisted segmentation: contour initialisation befor registration (a), after registration using the CICP algorithm (b), and after segmentation using Chan-Vese based method (c)

ACKNOWLEDGMENT This work is part of a project granted by the French Region Centre which associates 3 laboratories located in Orléans, France : the IEM (Transgénèse et Archivage d'Animaux Modèles) laboratory of CNRS, the CBM (Centre de Biophysique Moléculaire) laboratory of CNRS, and the PRISME (Pluridisciplinaire de Recherche en Ingénierie des Systèmes, Mécanique et Energétique) Institute of the University of Orléans.


Davi Gasparini
email: davig@sc.usp.br

Fernandes Cunha

Doron Grull
email: doron.grull@gmail.com

Pedro Caetano

Sanches Mancuso
email: mancuso@usp.br

A novel integrated concept of urban water management in a megalopolis from Latin America (São Paulo, Brazil): risk or opportunity?

Keywords: Developing countries, management, in situ treatment, urban areas, water quality

d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

Urban water management is a challenge task worldwide and especially in developing countries, which are normally characterized by rapid population increase and sudden shifts in land use, lack of sanitation infrastructure facilities and inadequate disposal of wastewater. Monitoring, management, remediation and revitalization of urban waters are necessary as the impacts over the quantitative and qualitative aspects of the aquatic systems and the conflicts among water users are more likely to occur in such areas (MISERENDINO et al. 2008, VERMONDEN et al. 2009, MISRA 2011). The sustainable development of urban territories thus requires a multidisciplinary approach to explore the urban systems as resources for the anthropogenic activities and needs (i.e. drinking supply, energy generation, irrigation, recreation) and to minimize the risks to the human health and the ecosystems balance.

The selection of water treatment methods must be associated with the specific characteristics of the target area (RIVETT et al., 2002), considering factors related to space and technology availability, waste management, energy demand and eventual conflicts among land owners, water users and the government sector. Taking into account that the Metropolitan Region of São Paulo (Brazil) has about 20 million inhabitants and high population density, in situ water treatment alternatives seemed to be convenient due to the lack of available areas to install off site facilities (CUNHA et al., 2010). Dissolved Air Flotation (DAF) is a widespread technology for water and wastewater treatment (RUBIO et al., 2002) with many specific applications (e.g. treatment of high heavy metals waters and emulsified oil wastes - ZOUBOLIS et al., 2000). The impurities are moved to the upper layers of the water column by tinny air bubbles, with posterior sludge removal. Coagulation (e.g. with ferric chloride or aluminium sulphate) and flocculation are required precedent steps and the overall efficiency of the flotation system depends upon the optimization of such processes (YAN et al., 2008).

We aimed to assess the feasibility of the in situ flotation treatment (pilot scale system: 10 m 3 /s) of the Pinheiros River, a polluted urban aquatic system located in São Paulo (Brazil), and posterior pumping of the treated water to the Billings Reservoir, a contiguous multipurpose water body. This is a novel approach because: i) to our knowledge, there is no similar system in the world (considering the average treated flow and the integrated concept of the prototype itself); ii) the pumping of the river treated water to the reservoir aimed to enhance the multiple water uses in the latter aquatic system, like energy generation and drinking supply. We conducted a comprehensive monitoring program during 32 months to evaluate the efficiency of the flotation treatment and to analyze eventual impacts over the reservoir water quality in relation to nutrients, organic compounds, metals and pathogens.

MATERIAL & METHODS

Study area

Billings and Guarapiranga Reservoirs are important water sources for the human activities in the Metropolitan Region of São Paulo, Southeastern Brazil (Figure 1). Billings Reservoir was built in 1927 and covers an area of approximately 127 km 2 , with the following geographic coordinates: 23º 47' S e 46º e 40' W. The main water uses in Billings are drinking (around 1.8 million citizens are supplied) and energy generation (Henry Borden Power Plant; 880 MW is the installed capacity). Accelerated artificial eutrophication and water quality degradation has been described in the recent years, with increasing densities of potentially toxic Cyanobacteria like Microcystis aeruginosa (MOSCHINI-CARLOS et al. 2009).

In situ flotation

We assessed a pilot-scale in situ flotation system treating the Pinheiros River water (10 m 3 /s; the final project would treat 50 m 3 /s). The process occurred on the river channel itself through two flotation stations separated by 4 km (Zavuvuz and Pedreira, Figures 1 and2). Ferric chloride was used as the coagulant (dosages varied between 50 and 400 mg/L; the rapid mixing time was about 30 s) and the flocculation step (slow mixing time ~ 0.5 h) preceded the flotation (whose recycle flow was about 8-10% of the affluent flow). The air bubbles on upward movement joined the colloidal particles of impurities, carrying them to the surface (as sludge). Rotating blades were used for dredging this material accumulated in the upper layers of the water column. A controlled landfill was the sludge final destination.

Monitoring

We selected 11 monitoring sites (Figures 1 and2) to evaluate the studied concept of urban water management (one in Tietê River: TIE -the tributary of Pinheiros River; four in Pinheiros River: S1, S2, S3 and S4 -upstream and downstream the flotation stations; six in Billings Reservoir: B1, B2, B3, B4, B5 and B6 -covering the riverine, transitional and lacustrine regions

RESULTS AND DISCUSSION

The in situ flotation system seemed to be a convenient approach for the Metropolitan Region of São Paulo. Considering aspects like lack of space to build off site structures, technology availability and incentive from the public authorities to the remediation of local polluted urban rivers, the prototype we tested was considered feasible. However, several constraints related to the low/insufficient efficiency for the removal of some variables (and the potential impacts to the Billings Reservoir), operational procedures and high chemical products consumption, sludge and solid waste production must be carefully examined. The approach itself represented an opportunity for recovering the water quality of a severely polluted river in São Paulo, but some inefficiencies we detected must be solved not to offer risks to the public health and to the multiple uses of the Billings Reservoir water.

Considering space restrictions, we present the results for some water variables and sampling sites. Data for all the parameters may be found at <http://www.mp.sp.gov.br/portal/page/portal/Billings>. The system efficiency for total phosphorus removal (90%) and dissolved oxygen increment (63%) in Pinheiros River water was relatively high. Some authors assessing the efficiency of other in situ flotation systems in Brazil, although quite smaller, reported higher removal efficiencies for total suspended solids (94%, treated flow: 0.15 m 3 /s, OLIVEIRA et al. 2000), biochemical oxygen demand (98%) and fecal coliforms (99.99%, treated flow: 0.05 m 3 /s, LOPES et al. 1999). Our removal efficiency for total suspended solids was 40%, lower than the percentage we were expecting. The high treated flow (10 m 3 /s) generates a more difficult condition to control the system. Moreover, the sludge removal was impaired due to the magnitude of flow and flux velocity, what certainly contributed for a worse final water quality.

Nitrogen-ammonia reduction percentage was almost zero (2%). By analyzing the average concentrations of some of the assessed variables in the Billings Reservoir (from B1 to B6), the impact over the water quality could be visualized. There was a trend of water quality improvement from B1 to B6 (B1 was submitted to the influence of the Pinheiros River treated water). Average concentrations of dissolved oxygen, for example, increased from 4.4 mg/L (B1) to 7.0 mg/L (B6) and the nitrogen-ammonia concentrations decreased from 6.4 mg/L (B1) to 0.3 mg/L (B6), what may be associated with the assimilation capacity of the aquatic system. Despite of the significant percentage efficiency for phosphorus removal, the remaining average concentration was still high in B1 (0.11 mg/L), contributing for the eutrophication of the headwaters of the Billings Reservoir. The iron concentrations in the water (0.11 mg/L in B1) suggested the impact of inappropriate operational procedures, like high consumption of chemicals during the coagulation step (ferric chloride). Therefore, we observed evidence of possible lack of criteria in the application of the coagulant, possibly as a result of the dosage changes, that were frequent in a process that was being tested. Although the tendency of iron is to form insoluble compounds and be immobilized in the sediment of the reservoir, it is advisable to review the dosages of coagulants to detect eventual hyper dosages.

The mean energy consumption of the pilot-scale flotation system was 42,000 kWh/day and the dewatered sludge production was significant (around 150 m 3 /day considering both flotation stations), boosted by the high consumption of coagulants. After centrifugation, the solids content in the sludge increased from 1-2% to 20%. However, considering the high amount of sludge production and the final destination of the material (a controlled landfill close to São Paulo city), managing this solid waste is a key point for the system sustainability.

CONCLUSIONS

The most important advantages of the proposed methodology and the integrated system for recovering the water quality of the Pinheiros River (São Paulo, Brazil) were:

i) The in situ approach seemed to be convenient for big cities like São Paulo due to the lack of available areas to build off site treatment structures. Moreover, since the treatment occurred on the river channel itself, there were smaller expenses with pumping structures;

ii) Besides the technology availability, we observed the local government willing to 1) recover the water quality of the Pinheiros River, an environmental issue and 2) boost the energy generation in the Billings Reservoir, an economic factor;

iii) The pilot-scale system treated a relatively high flow (10 m 3 /s) and the frequency of the laboratory analyses produced a significant number of monitoring data (over 200,000 results on water quality) during the 32 months the system was operating; iv) Quantitatively speaking, the flow transferred to the Billings Reservoir after the flotation treatment (~10 m 3 /s) favoured the multiple water uses in the reservoir (i.e. the additional flow was important for increasing energy generation and drinking water production);

v) The in situ flotation system reached satisfactory percentage removal of total phosphorus (90%) from the water, contributing to the decrease of phosphorus loads to the Billings Reservoir. The flotation stations also increased the dissolved oxygen concentrations in the water, although the increment levels were below the expected ones;

On the other hand, we could also detect some disadvantages and limitations of our system, including:

i) Interruptions occurred during the 32 months of the system operation for technical repairs and maintenance. Parameters like coagulant dosage and slow and rapid mixing gradients need adjustments to increase the overall flotation efficiency. We observed high soluble iron concentrations in the treated water, what was associated with no optimum ferric chloride dosages during the coagulation process;

ii) There were some difficulties regarding operation and maintenance of the prototype considering the influence of many external factors over an "opened" system -rainfall and other weather attributes, natural and anthropogenic-induced water quality temporal and spatial variability of the river;

iii) The treatment facility was not able to remove nitrogen-ammonia from the Pinheiros River water. High concentrations of this nutrient were observed in the riverine zone of the Billings Reservoir (B1), what could have implications for the eutrophication of the aquatic system. There is a need to find alternative/complementary units to control the nitrogen-ammonia concentrations in the water that is pumped to Billings, including biological processes; iv) Electrolytic flotation (which does not require the use of coagulants) or membranes are technologies that should also be tested as alternatives to overcome the limitations of the in situ flotation system;

v) The sludge removal unit must be improved. The inefficiency of this process affected the final water quality (i.e. by increasing the total suspended solids concentrations and decreasing the overall rates of pollutants removal from the water). Also, one of our biggest concerns was the final destination of all the dewatered sludge (with 20% of solids) that was produced everyday (about 150,000 L). During the 32 months we ran the system, the sludge was sent to a controlled landfill. However, this mechanism can become costly over time. It is necessary to improve the sludge dewatering processes and to look for alternative solutions for the material disposal;

vi) The treated water effects over the Billings Reservoir water quality were negative. The monitoring program revealed that the headwaters (B1 and B2) of the reservoir were affected by the effluent of the flotation system. The monitoring results also suggested the assimilation capacity of the water body, with progressive water quality increase down the reservoir. Further studies and data analyses are necessary to assess the temporal and spatial magnitude of the real impacts over Billings Reservoir and to estimate these impacts considering that the final project would treat 50 m 3 /s.

In summary, the in situ flotation system may be considered an opportunity for recovering the Pinheiros River water quality and favouring the multiple water uses in the Billings Reservoir because 1) the in situ approach is convenient for a megalopolis like São Paulo, 2) technology is available and 3) the government incentives may be used as a source of money and as a way to involve local people in the decision-making process. Nonetheless, we detected many inefficiencies and gaps that must be overcome. At the present stage, we believe the system may offer risks to the Billings Reservoir, including water quality degradation and its interface with public health issues.

In addition, the high amount of sludge has to be managed with emphasis on volume reduction and some alternative final destination. Cleaning up the river water should not mean transferring the problem to somewhere else (as solid waste). Urban waters in developing countries are such a challenging issue and our project seems to be an important contribution for the water resources management in such areas, focusing on integrative approach, technology application, environmental quality and sustainability in the long-term.

Figure 1 :Figure 2 :

 12 Figure 1: São Paulo State (Southeastern Brazil) and a scheme with Pinheiros River, Guarapiranga Reservoir and Billings Reservoir, including the approximate location of the monitoring sites

•

  CUNHA D. G. F., GRULL D., DAMATO M., BLUM J. R. C., LUTTI J. E. I., EIGER S. and MANCUSO P. C. S. (2010). On site flotation for recovering polluted aquatic systems: is it a feasible solution for a Brazilian urban river? Water Science and Technology 62, 1603-1613. • LOPES M. A. B. N. and OLIVEIRA J. C. G. (1999). O processo de flotação em fluxo como alternativa de despoluição de lago urbano -caso Aclimação na cidade de São Paulo (The on site flotation process as an alternative to cleaning up an urban lake -Lago da Aclimação, São Paulo, Brazil). Annals of 20 o Congresso Brasileiro de Engenharia Sanitária e Ambiental. Rio de Janeiro (RJ), Brazil: ABES, pp. 2500-2509. • MISERENDINO M. L., BRAND C. and DI PINZIO C. Y. (2008). Assessing Urban Impacts on Water Quality, Benthic Communities and Fish in Streams of the Andes Mountains, Patagonia (Argentina). Water, Soil & Air Pollution 194, 91-110. • MISRA A. K. (2011). Impact of Urbanization on the Hydrology of Ganga Basin (India). Water Resources Management 25, 705-719. • MOSCHINI-CARLOS V., BORTOLI S., PINTO E., NISHIMURA P. Y., FREITAS L. G., POMPÊO M. L. M. and DÖRR F. (2009). Cyanobacteria and Cyanotoxin in the Billings Reservoir (São Paulo, SP, Brazil). Limnetica 28, 273-282. • OLIVEIRA J. C. G., NETTO A. M., ANGELIS J. A. and BARBOSA, M. A. (2000). Estacão de flotação e remoção de flutuantes do Parque do Ibirapuera -São Paulo-a aplicação do processo de tratamento por flotação em fluxo para a recuperação de lagos urbanos (Flotation station and removal of floating material in Ibirapuera Park -São Paulo, Brazil-the application of on site flotation for the recovery of urban lakes). Annals of 21 o Congresso Brasileiro de Engenharia Sanitária e Ambiental. João Pessoa (PB), Brazil: ABES, pp. 1-9. • RIVETT M. O., PETTS J., BUTLER B. and MARTIN I. (2002). Remediation of contaminated land and groundwater: experience in England and Wales. Environmental Management 65, 251-268. • RUBIO J., SOUZA M. L. and SMITH R. W. (2002). Overview of flotation as a wastewater reatment technique. Minerals Engineering 15, 139-155. • VERMONDEN K., HERMUS, M. A. A., van WEPEREN M., LEUVEN R. S. E. W., van der VELDE G., SMOLDERS, A. J. P., ROELOFS, J. G. M. and HENDRIKS A. J. (2009). Does upward seepage of river water and storm water runoff determine water quality of urban drainage systems in lowland areas? A case study for the Rhine-Meuse delta. Hydrological Processes 23, 3110-3120. • YAN M., WANG D., QU J., NI J. and CHOW C. W. K. (2008). Enhanced coagulation for high alkalinity and micro-polluted water: the third way through coagulant optimization. Water Research 42, 2278-2286. • ZOUBOULIS A. I. and AVRANAS A. (2000). Treatment of oil-in-water emulsions by coagulation and dissolved-air flotation. Colloids and Surfaces 172, 153-161. 02-WWW-YES-2011-Cunha-2011_03_31.doc

  ). Altogether, 148 water variables were quantified from August 2007 to March 2010 with different frequencies (e.g. daily, weekly or monthly), following APHA (2005) methods. All the analyzed variables are important in relation to sanitary, environmental and health aspects, including metals (aluminium, cadmium, copper, iron, lead), biological indicators (biochemical oxygen demand, thermotolerant coliforms, Cryptosporidium sp., Giardia sp.), nutrients (total phosphorus and nitrogen, nitrate, nitrogen-ammonia), organic compounds (aldrin+dieldrin, 1.2-diphenylhydrazine, 2.4.6trichlorophenol, endosulfan, endrin, 4.4-DDD, fluoranthene) and other physical and chemical variables (apparent color, conductivity, dissolved oxygen, total suspended solids, turbidity). The full list of all the quantified variables may be found at the website of the São Paulo State Attorney (MP-SP): <http://www.mp.sp.gov.br/portal/page/portal/Billings>.

TABLE 1 : Overall removal or increment efficiency (%) achieved by the flotation system (S1 vs. S4) for some water variables in the sampling sites in the Pinheiros River and average concentrations in the Billings Reservoir (B1-B6)

 1

	Variable	Removal efficiency*	B1	B2	B3	B4	B5	B6
	Dissolved oxygen (mg/L)	63% (increment)	4.4	5.9	5.8	6.7	6.9	7.0
	Iron (soluble, mg/L)	31%	0.11	0.05	0.04	0.04	0.03	0.05
	Nitrogen-ammonia (mg/L)	2%	6.4	1.9	0.7	0.5	0.6	0.3
	Total phosphorus (mg/L)	90%	0.11	0.04	0.05	0.04	0.03	0.03
	Total suspended solids (mg/L)	40%	13	8	7	6	7	8

* CUNHA et al. (2010)

11thWWW YES, Arcueil, France, 6 -10 June 2011

11thWWW YES, Arcueil, France, 6 -10 June 2011 CUNHA et al


Anne-Marie Jolly

Christophe Léger

Guy Lamarque
email: guy.lamarque@univ-orleans.fr

Christophe Leger
email: christophe.leger@univ-orleans.fr

CONCEPTION OF A NEW ENGINEERING CURRICULUM IN "SMART BUILDINGS"

Keywords: electronics, energetic efficiency, engineering education, home automation

The disaffection of students for electrical engineering led us to define new curricula based on concepts of electronics, electrical networks and sensors that could attract students whose interest lies in civil engineering or sustainable development.

The idea of a course leading to jobs such as integrator of solutions for energetic efficiency of buildings, or designer of systems for smart homes revealed to be fitted as well with the needs of companies as with the interest of young people. The point of view of the design of the curriculum is for 2/3 the point of view of the IEEE engineer and for 1/3 the point of view of the building engineer.

To go through such a transverse project, methodology of brainstorming and team efficiency is necessary. The result is a curriculum considered by major companies of the domain as useful and necessary, and by the team of researchersteachers of the engineering school as a project allowing a better knowledge of the fields of each other. The paper presents the methodology of development of the project in front of the needs in energetic efficiency of buildings and home caring of elderly. The course obtained and how companies and research organisms follow and help the approach is developed too. A comparison with other approaches of new curricula in this field, based on civil engineering concepts is also presented.

INTRODUCTION

The number of problems related to energy management is getting bigger and bigger. Engineers, who are the actors of many technical solutions, should be able to propose solutions to them. Energy in building is one of the concerned fields because it is at the cross of two fields very distinct during engineering courses: civil engineering and electronics [START_REF] Becker | Why don't young people want to become engineers? Rational reasons for disappointing decisions[END_REF], [START_REF]Engineering: issues, challenges and opportunities for development[END_REF].

In the same time, there is a real need to make students undergo studies in electronic engineering, while civil engineering meets a huge interest among men and women.

Companies are complaining because they do not find engineers able to manage a project intended to find global solutions for less consuming and comfortable buildings.

In the same time, great projects are emerging, involving academics and companies. There is not enough knowledge concerning thermal behavior of building depending on meteorological solicitations, new sources of energy or new algorithms of regulation. For that reason, research and development platforms aimed at those studies are in under elaboration.

To satisfy all these needs that will be the needs of tomorrow, it was necessary to imagine a specific course developing the skills necessary for jobs linked either to energy, comfort or easiness of life in buildings.

THE TWO OBJECTIVES

When speaking about smart buildings, two main directions appear [START_REF] Sinopoli | Smart buildings: a handbook for the design and operation of building technology systems[END_REF], [START_REF] Wang | Intelligent buildings and building automation[END_REF]:  The first one concerns the energetic efficiency: in the house or in office building you have a great number of heat sources that can be controlled through electronic means: geothermic science, solar cells, fossil energy consuming boilers…  The second one is related to the comfort and easiness of life for people living or working in the building: home automation, monitoring or care for elderly.

The curriculum aims to give skills in both fields, concerning the teachings in electronics, networks…the needs are the same because techniques for data transmission and data fusion are the same.

THE METHOD TO BUILD THE CURRICULUM

It is not in the use of teacher to build courses that are transverse to two fields of knowledge: civil engineering and electronic engineering, so a brainstorming methodology was used to come from skills expected in the jobs.

In our engineering school Polytech Orléans, we have the opportunity to have on the same campus 3 different categories of engineering courses: electronic engineering, civil engineering, energetic and mechanic engineering.

The first step was to mix teachers and researchers in electronics, renewable energy, materials and mechanics, heat [Tapez un texte] energy, networks, automation…. They discussed about the skills necessary for jobs related to those fields:  Technical management of buildings  Design of electric or electronic devices for building  Management of energy inside buildings  Eco-design of buildings These discussions were very fruitful for all of them because they discovered each other's fields that are complementary All French engineers have basic knowledge in mathematics, computer science and management of project, but in this particular course, 3 great areas have been considered as the heart of the teaching:  Management of energetic needs  Management of people and assets  Habitat and environment

The first item includes energetic optimization, ecodesign, renewable energy, management and optimization of energetic needs, home automation and electric devices for home comfort.

The second one is related to sensors, communication networks, interoperability, multimedia, video surveillance, safety, caring people at home

The third one concerns waste and water treatment, environmental norms about buildings, Electromagnetic compatibility.

Those points are then declined according basic teaching areas: electronics, automation, computer science, mechanics and materials, energetic, heat energy. During the third year, there are less leaching in front of student because half of the year is devoted to a synthesis project.

BENEFITS EXPECTED

The benefits are numerous:  For companies: they are satisfied to have graduated students that can be the coordinators of activities in the fields of energetic efficiency and smart buildings.



CONCLUSION

The course in itself will begin in September 2011 but we have already tested some of the teachings in a curriculum developed in Orléans, it showed the global interest of this project. The development of the course in Chateauroux, a city not far from a great company as Legrand is interesting to be able to show very quickly to the student the practical application of the courses. The origin of the creation of this curriculum: a brainstorming of electronic teachers to decide how to make their course more attractive, makes the result obtained different of other curricula in smart buildings: for example in Université de Cergy-Pontoise [START_REF] Wang | Intelligent buildings and building automation[END_REF] or in Polytech Nice(an engineering school of the same network as Polytech Orléans) they decided to make a civil engineering course become a smart building course. In those curricula the proportion of IEEE an civil engineering is opposite as ours. The two categories of engineers will have to work together in the future.

  The second year is devoted to the tools specifically used for designing smart devices. At this moment the students can realize projects that are more linked to the technique of smart buildings than previously.

	modes, emission and hypersensitivity Project		Integration Arrangement of housing spaces.	150
		200	Architectural typology	50
	Water and Energy Renewable and Alternative energy Ecodesign of habitat Thermoregulation	50 50 50	Housing accessibility, interior architecture Construction, urbanism and environment law Sensorial Design applied to materials, Design and structure	50 50
	Water management	50	of habitat	50
	Project		Project
		200		200
	Project management Team management tools Safety engineering	20 20	Human, Economic, Management, Language Sciences Career plant approval	6
	Project management	30	Interview preparation	4
			Human resources	8
		70	Economics and management -
	Human, Economic,		strategy	16
	Management, Language		Economics and management -
	Sciences		marketing	12
	Carrier plan	6	Economics and management -
	Human ressources	8	business plan	8
	Labour law	6	English language	66
	Business law	6		120
	Environmental management	10	Number of hours per student	470
	Information technology law	12
	English language	112
		160
	Number of hours per student	730
		Time in front
	3rd year courses	Of students
		Course
	Process Control, man-machine
	cooperation
	Process control, Field bus,
	Human-computer interaction	50
	Image and information analysis
	and processing	50
	Standards : Advantages and aims
	illustrated by application	50
	Project

THE 3 YEAR COURSE

The courses begin two years after A Level, it lasts 3 years, and during this time the student receives 1800 hours of academic teaching. The time left can be used for a trainee in enterprise. During the first year (last year of Bachelor Degree), the student learns basics about electronics, materials, applied mathematics. These skills are necessary for a necessary adaptation to the job he will occupy all along his career. He is also initiated to the team work through projects.

st Year Courses


V Guillet

P. Ravier G Lamarque
email: guy.lamarque@univ-orleans.fr

C Léger

Improving the power line communication signal-to-noise ratio during a resistive load commutation

Keywords: Commutation, impulse noise, Signal-to-Noise Ratio (SNR) improvement, zero-crossing

In any cable or power line communications, impulse noise is known to be the most difficult noise to filter. In particular, non periodic asynchronous impulse noise is impossible to predict. Under such noise conditions, the OFDM 1 symbol generally used in PLC 2 is corrupted. To overcome this problem, the signal-to-noise ratio is generally improved by detecting and/or filtering the noise. This leads however to heavy detection and computing time in comparison with the disturbance duration. In this paper, we study the parameters of the noise generated by a load commutation and propose a new approach that consists in controlling the commutation instant of the load. This approach reduces by up to 15 dB the asynchronous impulsive noise emitted by a resistive load in a 40.96-µs typical Homeplug AV 3 OFDM symbol duration. Synchronisation is integrated in electronic commutation system. Results show that the load value does not influence the magnitude of the impulse noise.

I. INTRODUCTION

Wireless communication has become increasingly common, particularly in portable systems. However, when the systems require a power supply, power line communication appears to be a good alternative solution. This communication channel requires no additional wiring, making it effortless and cheap to set up a network in existing buildings. Moreover, it offers Triple Play facilities (Internet, VoIP, Multimedia) thanks to a high PHY 4 bit rate, in the range of a few hundred Mbps (Mega bits per second) raw data, and can operate over a distance of around one hundred meters. Achieving such a high bit rate involves optimizing allocation of the authorized bandwidth. An appropriate modulation such as OFDM 1 , which has a good spectral efficiency, enables the overall bandwidth to be taken into account [START_REF]Homeplug av specifications[END_REF]. Nevertheless, it is also very important to have precise knowledge of the topology of the communication channel [START_REF] Banwell | A new approach to the modeling of the transfer function of the power line channel[END_REF] [START_REF] Anastasiadou | An experiment setup for characterizing the residential power grid variable behavior[END_REF], and the associated noise sources [START_REF] Zimmerman | An analysis of the broadband noise scenario in power-line network[END_REF]. This paper is based on "Reduction of the impulsive noise emitted by a resistive load commutation," by V. Guillet, G. Lamarque, P. Ravier and C. Léger, which appeared in the Proceedings of the 12th IEEE Int. Symposium on Power Line Communications and Its Applications (ISPLC), Jeju Island, Korea, April 2008. c 2008 IEEE. 1 OFDM: Orthogonal Frequency Division Multiplexing.

2 PLC: Power Line Communication. 3 Homeplug AV: PLC protocol from homeplug consortium for Audio and Video. 4 PHY: Lowest layer in the ISO model network communication. It is well known that in the power line channel, the noise does not agree with the classical Additive White Gaussian Noise (AWGN) model [START_REF] Zimmerman | An analysis of the broadband noise scenario in power-line network[END_REF]. The model in figure 1, presented in [START_REF] Zimmerman | An analysis of the broadband noise scenario in power-line network[END_REF], is therefore generally preferred. In this model, the communication channel is mainly disturbed by a set of five noise sources.

The background noise sources [START_REF] Liu | Broaband characterization of indoor powerline channel[END_REF] (narrow band and coloured noise) are frequency localized. Conversely, the impulse noise sources [START_REF] Chan | Amplitude, width, and interarrival distributions for noise impulses on intrabuilding powerline communication networks[END_REF], [START_REF] Phillips | Development of a statistical model for powerline communication channels[END_REF] are time concentrated. In the latter class, some are periodic (periodic synchronous/asynchronous impulse noise) while the others are not (asynchronous impulse noise).

Among all the types of noise, the asynchronous impulse one is probably the most difficult to deal with. Numerous methods have been developed to detect and/or filter such noise. In instance, for noise sources synchronized to mains [START_REF] Hirayama | Noise analysis on wide-band plc with high sampling rate and long observation time[END_REF], periodic and predictive [START_REF] Katayama | Linear predictive detection for power line communications impaired by colored noise[END_REF] or detected into OFDM subchannels [START_REF] Avril | Impulsive noise detection on masked carriers[END_REF], the Signal-to-Noise Ratio will be reduced.

In terms of topology, two elements need to be taken into account: the cable model and connected loads [START_REF] Assimakopoulos | Measurements and modeling of in-house power lines installation for broadband communications[END_REF]. Generally, rigid cable is used for fixed installations because it is cheaper than a flexible (multi-wire) one, which is preferably used for extensions due to its ease of installation. As the power line channel is limited to fixed installations, only rigid cables wil be considered here. In order to improve the PLC Signal-to-Noise Ratio (SNR) during a resistive load commutation, we have studied the influence of the cable length. The second element of the channel is the load. Among existing loads, we focus on the most elementary ones, namely heaters. Three aspects of the loads are examined: the commutation instant, the nature of the commutation system and the electrical load value.

The paper is organized as follows. Section II introduces the commutation system and the method used to analyze the noise emitted. Section III presents the results of the commutation of a simple resistive 500 W mechanical radiator for three different commutation instants (0%, 50% and 100% of the main amplitude). Section IV shows the effect of the line length and its consequences on the bandwidth. The mechanical commutation technology (relay) is compared with the electronic one (triac) in section V. Finally, section VI presents the effect of the commutated load value using an electronic commutation which will be shown to be the least noisy technology.

II. MATERIALS AND METHODS

In this study, the commutation effects of a load are analyzed using the schematic presented in figure 2 and described in the following paragraphs.

A. The cable

In-house installed cables do not use a global shield for the two or three copper conductors, but use corrugated pipes. In this study, a 3G cable (See Table I) for industrial and tertiary sector buildings is used. This cable is composed of a global shield, making the inter-conductor distance constant.

B. The load and the commutation

The load consists in a 240V / 500 W radiator placed at the end of the cable. This type of load is purely resistive. Its commutation is done using a relay technology, which is equivalent to the thermal switch used in a radiator thermostat. A digital dephasing system synchronised to the mains voltage is used to determine the relevant commutation instant (Fig. 3).

The zero-crossing circuit detects the instant of a zero amplitude value of the mains power supply. Detection is carried out using an optocoupler [START_REF] Dostert | Power-line comunications[END_REF]. At this precise instant, a digital counter implemented in a CPLD 5 (Xilinx CoolRunner II [13]) starts counting. A 100 kHz system clock increments the counter value with a precision of t ≈ 10 µs on the commutation instant. When the delay value is reached, the desired state of the commutation takes effect.

C. Signal acquisition and processing

The analysis of the channel is carried out using a standard capacitive coupling circuit. The circuit is designed to reject low frequencies (50 Hz), carried by the mains power supply, but to let high frequencies pass through. The bandwidth is in the range of 100 kHz to 100 MHz. The analyzer is a dual input acquisition board GAGE CompuScope 12400 [START_REF]Gage compuscope 12400 specifications[END_REF], with 12 bits resolution, and a fixed sampling rate of 200 MHz. Due to such a high data flow, the on-board memory avoids the loss of samples during acquisition. A 40 dB attenuator is used to limit saturation of the acquisition tool. The input impedance of this attenuator is 50 Ω. Signal processing is carried out using a MATLAB environment in diferred time. The measurement includes an overvoltage protection using a sufficient bandwidth to ensure correct analysis.

In order to reduce the random part of the commutation signal and the contact bounce, ten acquisition sequences are carried out for each parameter (cable length and dephasing value).

III. MECHANICAL THERMOSTAT RADIATOR BEHAVIOR

The observed time duration of commutation pulses is from 1 µs to 50 µs. In a few cases, some bounce can be observed (see figure 4). This is due to the relay technology used by the commutation system. However, such bouncing can also be observed in a thermal switch commutation employed in radiator thermostats.

A time-frequency analysis is carried out using Short-Time Fourier Transform (STFT) (Fig. 4). The square modulus of the STFT also called spectrogram is estimated using 1024-points rectangular windows (corresponding to about 5 µs window duration). The 1024-points Fast The time frequency diagram (Fig. 4) clearly demonstrates that during the full pulse duration time, all frequencies, including the authorized PLC bandwidth, are affected. Moreover, the disturbance duration (from 2 µs to 20 µs) is of the same order as the OFDM symbol duration of PLC standard protocols (from 10 µs to 100 µs). This shows that the disturbance time and the detection/processing time are equivalent, meaning that detecting pulses is not efficient. We therefore propose a new approach to control the commutation instant, in order to reduce the noise.

Fig. 5 presents the noise PSD (Power Spectrum Density) obtained using a Welch periodogram over 2048 samples with a rectangular window and without any overlap in a 40.96-µs typical Homeplug AV OFDM symbol duration. The time delay is set at 0, 8 and 25 percent of the power supply period, corresponding respectively to a load commutation when the power supply sinusoidal amplitude is equal to 0%, 50% and 100% of the maximum voltage value. A 30-meter cable is used in this comparison. Fig. 5 shows that the noise floor increases as a function of the delay of the commutation. The disturbance duration is measured from 2 to 3 OFDM-symbols in the worth case, but without commutation bounces.

In order to easily estimate the SNR improvement, an approximation model of the background noise is used (Equation 1, [START_REF] Esmailian | Characteristics of in-building power lines at high frequencies and their channel capacity[END_REF]).

P (f ) = a -b.f c (dB/M Hz) (1)
The fitting curves are presented in figure 6. The a, b and c parameters are given in table II. It can clearly be seen from Fig. 6 that the noise power is lies between the noise level given by the curves at 0% and 25% commutation instant. Controlling the commutation instant limits the noise floor to its lower value. In this way, the SNR can be improved by about 15 dB in a 40.96-µs typical OFDM symbol duration. This improvement is enhanced by other considerations: fixing the time-synchronisation to the zero-amplitudevoltage instant (t zci ) of the mains power will reduce the step sollicitation to the commutation system and also to the load. Consequently, the breaking capacity will be preserved and the dissipated power reduced.

IV. INFLUENCE OF THE CABLE LENGTH

In order to assess the independence of the cable length, the experimentation was also carried out with a 70-meter cable. The PSDs obtained are presented in figure 7. Figure 8 presents the fitting results.

The PSD and the fitting curves are estimated in the same manner as in section III. Table III gives the parameters obtained for the fitting.

The fitting curves (Fig. 6 and Fig. 8) obtained for a 30meter and a 70-meter cables show similar behaviour for a given commutation instant. Consequently, controlling the commutation instant may indeed reduce the SNR by about 15 dB, irrespective of the cable length. In fig. 5 and7, ripples are visible. Their frequencies appear to increase with cable length. The ripple might be related to the line characteristic impedance mismatch. In order to verify this hypothesis, a cable analysis was performed, using the same analysis circuit, but replacing the load by a generator and leaving the commutation switch closed (Fig. 9). The generator is an arbitrary waveform generator (GAGE CompuGen 4300 [START_REF]Gage compugen 4300 specifications[END_REF]) using a white noise sampled at the frequency of 300 MHz. The output of the generator matches the full scale input of a line driver (OPA2674, [START_REF]Opa2674[END_REF]) avoiding saturation. Another circuit is added on the line driver output. The results for a 30-meter, 50-meter and 70-meter cable are presented in fig. 10.

The line impedance mismatch will produce reflections over the line. These reflected signals will be added to the measured signal after a propagation time given by equation 2 :

t p = l v p = l C √ r , using v p = C √ r ( 2
)
where l is the length of the cable, v p is the propagation speed, C ≈ 3.10 8 m/s is the light speed in vacuum and r is the permittivity of the dielectric. During a propagation time t p , it is possible to observe a k number of a 1 f sinusoidal signal period.

t p = k * 1 f (3)
A maximum value is obtained in f k for each integer value of k:

f k = k t p (4)
Moreover, the frequency distance between two local maxima is ∆F :

∆F = f k+1 -f k = k + 1 t p - k t p = 1 t p (5)
The measurement enables the cable propagation time and the cable dielectric permittivity to be evaluated using equation ( 2):

1 ∆F = t p = 0.52µs, √ r = C l tp , r ≈ 3.12 (6)
The frequency ripple value (the distance between two local maxima, ∆F ) for different cable lengths (1, 20, 30, 50, 70, 78 meters) is measured using zooms such as those shown on fig. 11.

Ripple measurements are reported in figure 12, where equation ( 2) is also plotted. The two curves are superimposed, demonstrating that the ripples are due to the impedance mismatch. Measurement of the frequency ripple value in Fig. 5 and Fig. 7 also verifies equation (2).

V. INFLUENCE OF COMMUTATION TECHNOLOGY

In section III and section IV, we have shown that the zero-crossing commutation (t zci ) is the least noisy situation. From now on, the t zci will therefore be used. In order to do so, the mechanical thermostat radiator is replaced by an electronic radiator. Its commutation is based on a triac and a zero-crossing detection. Moreover, this kind of radiator accounts for 71% of electrical heaters in residential houses sold in 1998 in France (AERE Study "Chauffage électrique en France" ). Since the end of 2006, this type of radiator is recommended by the thermal regulation "RT 2005" as it provides a better energy efficiency (Source: Thermor 6 , ADEME 7 ).

Figure 13 compares the PSD of the mechanical commutation w.r.t. the PSD of the electronic commutation. Even though these two curves are obtained using a 30meter cable at t zci and for the same electrical consumption (500 W), the curves are not merged. The thermal switch commutation is about 15 dB noisier than the triac 6 Thermor: International company on white and grey goods. one. This could be explained firstly by the technology differences between the electronic and the mechanical heating load. Secondly, for practical wiring reasons, the commutation circuit is not in the same place. Fig. 14 presents the commutation configuration of an electronic radiator. It is to be compared with fig. 2. These two wirings are identical at low frequencies, but may exhibit different behavior at higher ones. Finally, the commutation technology used in the commutation tool is different. Further investigation is neccessary to fully understand the influence of all these parameters. Considering the temporal signals (figures 15 and 16), the disturbance duration is reduced to one OFDM-symbol. The pulse amplitude is lower for an electronic thermostat radiator than for a mechanical one. The scale factor between the two pulse magnitudes explains the almost constant 16 dB difference observed between the two spectrum curves shown on Fig. 13.

In order to overcome the uncertainties due to the commutation system and heating technology, the rest of the study will use the most favourable case, i.e. a triac commutation system synchronized with the zero-crossing. We now turn to assessing the importance of the load value.

VI. INFLUENCE OF THE ELECTRONIC RADIATOR LOAD

VALUE

The commutation load at t zci fixes the background noise level (III) irrespective of the length (IV). The last parameter to study is the effect of load value on the commutation. Fig. 17 shows the comparison between All the curves of Fig. 17 are superimposed. This highlights the fact that for the same commutation system and the same heating load technology, the impulse response does not change. It can therefore be concluded that the noise generated is independent of the electrical power consumption value, i.e. the impedance at the mains frequency (50 Hz).

The noise floor of the measurement setup is about -27 dB. This means that, considering the zoom on Fig. 18, frequencies up to 5 MHz are concerned by the impulse noise.

VII. CONCLUSION

In this study, we have shown that the noise generated by asynchronous aperiodic impulse sources can be easily and significantly reduced. Indeed, the SNR, in a 40.96 µs typical Homeplug AV OFDM symbol duration, can be improved by up to 15 dB simply by controlling the commutation instant of a resistive load. In this way, the asynchronous noise is made synchronous: the pulses are always located at the zero-crossing instant. In that case, the data rate is increased, and the synchronization sequence can be less corrupted.

Moreover, we have shown that the heating load technology, the position of the commutation circuit and the commutation system may influence the impulse noise power generated by about 16 dB. Further study is necessary to investigate the role of each parameter involved in the 16 dB difference.

Figure 1 .

 1 Figure 1. Power line channel noise description.

Figure 2 .

 2 Figure 2. Analysis of the commutation effects.

Figure 3 .

 3 Figure 3. Commutation tool.

  5 CPLD: Complex Programmable Logic Device.Fourier Transform (FFT) spectra are evaluated on sliding windows with 95% overlap between the slices.

Figure 4 .

 4 Figure 4. Time frequency analysis of a commutation.

Figure 5 .

 5 Figure 5. Comparison of the PSD waveforms as a function of three commutation instants for a 30-meter cable.

Figure 6 .

 6 Figure 6. Fitting curves with respect to the background noise model for a 30-meter cable.

Figure 7 .

 7 Figure 7. Comparison of the PSD waveforms for a 70-meter cable.

Figure 8 .

 8 Figure 8. Fitting curves with respect to the background noise model for a 70-meter cable.

Figure 9 .

 9 Figure 9. Method to analyze the bandwidth of the cable.

Figure 10 .

 10 Figure 10. Ripples in the bandwidth.

  Zoom for a 70-meter cable.

Figure 11 .Figure 12 .

 1112 Figure 11. Zoom on ripples in the bandwidth.

  7 ADEME: French Environment and Energy Management Agency.

Figure 13 .

 13 Figure 13. Commutation technology comparison at t zci and for 30meter cable.

Figure 14 .

 14 Figure 14. Analysis method for the electronic load commutation.

Figure 15 .

 15 Figure 15. Commutation signal of a mechanical thermostat radiator.

Figure 16 .

 16 Figure 16. Commutation signal of an electronic thermostat radiator.

Figure 17 .

 17 Figure 17. Load comparison at t zci and for 30-meter cable.

Figure 18 .

 18 Figure18. Zoom on the load comparison at t zci and for 30-meter cable.

TABLE I .

 I CABLE USED FOR THE TEST.

	Conductor type	Solid
	Manufacturer	La Triveneta Cavi
	Reference	U1000 R2V
	Class	1, Solid
	Insulation ( inner / outer )	PR / PVC
	Approximated permittivity 3.18 / 2.25 (Farad/meter) (inner / outer)

TABLE II .

 II FITTING CURVES PARAMETERS FOR A 30-METER CABLE.

TABLE III .

 III FITTING CURVES PARAMETERS FOR A 70-METER CABLE.

	Commutation instant	Switched Amplitude	a	b	c
	0%	0%	-209	246	-0,04
	8%	50%	-100	127	-0,05
	25%	100%	-31,6	84,8	-0,15

JOURNAL OF COMMUNICATIONS, VOL. 4, NO. 2, MARCH 2009 © 2009 ACADEMY PUBLISHER

© 2009 ACADEMY PUBLISHER

ACKNOWLEDGMENT

This work has been carried out in the framework of the French competitiveness cluster Science and Systems of Electrical Energy (S 2 E 2 ) -SESAME GEDELOCunder contract n o 2005-4020-06A-066.

Vincent Guillet was born in Gien, France on 12 November 1982. He received his MS degree in Electronics Signals and Microsystems from the University of Orléans, France, in 2006. He is currently a Ph.D. candidate at the Prisme Institute, University of Orléans, (Polytech'Orléans), France. His research interests include channel characterization, topologies and power line connected devices influences.

Guy Lamarque received his Ph.D. degree in engineering science from the University of Orléans, France, in 1992. His dissertation presents a method that improves in situ apparent ground resistivity measurement from spectral analysis of the magnetotelluric field components. This algorithm has been implemented in real time. In 1993, he joined an engineering school (Polytech'Orléans) where in 2005, was appointed head of the electronics department. He is currently working at the Prisme Institute, University of Orléans, France. His research interests focus on signal processing and its applications including real time implementation considerations.

Philippe Ravier was born in Chambéry, France on 22 February 1969. He received his Ph. D. degree in engineering science, specializing in signal, image and speech processing, from the National Polytechnic Institute in Grenoble (France) in July 1998. Since 1999, he has been an assistant professor at the Ecole Polytechnique of the University of Orleans (Polytech'Orléans), France. His research deals with wavelets for detection purposes and time -frequency analysis in various application areas (underwater acoustics, electrophysiological signals and radioastronomy).

Christophe Léger is a full professor at the Prisme Institute of the University of Orléans, France. From the university of Orlans, he obtained a MS in electronics in "Signal and Image processing, Real-Time Systems" in 1990, and received a Ph.D. degree in Engineering Sciences in 1993. Christophe Léger's primary research interests concern signal and image processing applied to biomedicine, including spatio-temporal interpolation, Fourier analysis, deformable dynamic models and data registration.


C Léger
email: christophe.leger@univ-orleans.fr

Dynamic surface representation needs in the field of cardiac imaging

Keywords:

In this communication, we expose the classical steps used in medical imaging to reconstruct dynamical organs such as the human heart. We indicate the limitations still encountered nowadays, and propose some potential perspective to improve the segmentation and reconstruction of the cardiac surfaces as a function of time.

Introduction

The reconstruction and visualization of closed surfaces is an active topic in the domain of medical imaging. Due to combined progresses of imaging systems and computer processing's carried out at the end of acquisitions, it is now possible to isolate, to reconstruct and to display the surfaces of various organs of human body. These works present multiples interests:

 Anatomic, in order to observe the inside of human body in a non invasive way, or to provide reference computer graphics representations (atlas),  Functional, to understand better how the body performs,  Diagnostic, to predict the potentiality or to identify the origin of a failure or a problem,  Therapeutic, to evaluate the progression or the remission of a disease, the efficiency of a treatment,  Etc. Depending on the applications, the reconstructed surfaces are either displayed separately or superimposed within the original images. The surfaces may also be used to delineate areas where biological parameters of interest are measured. Among all the organs of human body that presents closed surfaces (kidney, bladder, prostate, spleen, gall bladder, lung envelope, cerebrum, etc.), the heart is the subject of particular interest. It is a vital organ, of which the operation is directly related to the patient survival, and which is widely studied since cardiac diseases correspond to a primary cause of death in the industrial countries, and therefore represents a major challenge of public health. In consequence, cardiac imaging exploits all medical imaging modalities, that is to say structural imaging, as ultrasound (echography), X rays (CT-scan) and magnetic resonance imaging (MRI), or functional imaging, as nuclear medicine (SPECT).

Method

The methods carried out to reconstruct the deformations of the surfaces of the heart as a function of time require generally 5 major steps:

1. Acquisition of bi (2D), tri (3D) or even quadri (4D) dimensional images, 2. Determination of the cardiac contours by image segmentation using 2D, 3D or 4D algorithms, 3. Association of the samples provided by contour segmentation, in order to produce deformable surfaces as a function of time, 4. Surface smoothing, often necessary because of the noise added to the samples, 5. Samples reorganization (using triangulation algorithms), then representation. The segmentation step (#2) strongly depends on the nature and the quality of the original images. It represents the most complex step of the process to carry out. To segment such cardiac images, the standard techniques of image processing used to locate the contours using derivative/differentiation methods are not efficient. This is particularly due to invisible portions of contours that have to be extrapolated because they do not exist, for example when the mitral valves between the left atrium and the lower part of the left ventricle are widely opened (cf. white stain at the bottom of the contour on Figure 1a,). To deal with this problem, algorithms based on active contours [START_REF] Kass | Snakes: Active contour models[END_REF] or surfaces [START_REF] Chan | Active Contours Without Edges[END_REF] are preferred, since they present the advantage to associate image information with a priori information on the shape or position of the expected contours or surfaces. Adding contour or surface information allows compensating the lack of information of the images. By setting constraints, the degrees of freedom of the segmentation algorithms are limited, and contour or surface evolvement is contained within probable domains compatible with reality. Thus, cardiac images known to be difficult to segment can be exploited by physicians.

Limitations

In order to reduce the complexity of the implemented algorithms, or limit the duration of the processing times, problems are sometimes resolved at lower dimensions than expected. Then, results are gathered to get back to the dimension of the initial problems and to provide acceptable solutions. For example, cardiac contours obtained at multiple levels (altitudes) are assembled to reconstruct a single surface of the heart (in opposition to 3D, the term 2D ½ is used to identify this type of reconstruction), or various surfaces are associated to represent the surface of the heart that varies as a function of time [START_REF] Souplet | Representation of the LV 3D phase dispersion using gated spect blood pool tomography[END_REF] (3D ½ is used instead of 4D). Unfortunately, such approaches introduce breaks of continuity, either spatially (2D ½), or temporally (3D ½). The only solution to deal with this problem is to carry out a posteriori additional approximations, in order to guarantee the regularity of the representations. Moreover, these approximations are useful to correct the uncertainty (due to noise) of the contours or surfaces samples provided at the end of the segmentation step, despite of the use of complex models [START_REF] Haddad | An anthropomorphic numerical model of the beating heart[END_REF], or the implementation of active contour or surface algorithms. The reconstruction errors are then corrected a posteriori using regularizing methods.

Conclusion

To reconstruct accurately the deformations of the heart and/or its cavities as a function of time (Figure 2), true 4D approaches must be developed, in order to take into account all the available information to compute each useful sample of the surface. Such approaches began to appear [START_REF] Cl | 4D reconstruction of the left ventricle during a single heart beat, from ultrasound imaging[END_REF], whereas others can be extended directly to 4D [START_REF] Ameur | New spline quasi-interpolant for fitting 3D data on the sphere: Applications to medical imaging[END_REF]. It remains to complete these methods, and to try to merge them with active surface algorithms in order to get tools that combine estimation and regularization at each step of the processes.

Figure 1

 1 Figure 1 presents cardiac images produced from four classical imaging modalities, which differ by their signal to noise ratio and their resolution.

Figure 1 :

 1 Figure 1: example of cardiac images. (a) ultrasound image (512512), (b) nuclear medicine image (6464), (c) MRI image (256256), d) X-Ray image (256256).

Figure 2 :

 2 Figure 2: example of 8 surfaces of the left ventricle of the heart reconstructed within a cardiac cycle.