Marine Bruneau

Thierry Mottet

Serge Moulin
email: serge.moulin@univ-fcomte.fr

Maël Kerbiriou

Franz Chouly

Stéphane Chretien

Christophe Guyeux

A clustering package for nucleotide sequences using Laplacian Eigenmaps and Gaussian Mixture Model

Keywords: DNA Clustering, Genomics, Laplacian Eigenmaps, Gaussian mixture model

published or not. The documents may come

Introduction

As the amount of available genetic sequences increases drastically, the need for scalable methods becomes urgent. A very important tool for dealing with large amounts of data is clustering. Clustering was successfully used for a large number of important applications recently. Clustering methods have thus demonstrated irrefutable efficiency for real-life applications to genetics and have provided extremely powerful tools to the community. In particular, the huge amount of molecular data available nowadays can help addressing new and essential questions in genomics if appropriate scalable methods are used. Sequence clustering is a key element among these tools [START_REF] Valot | What it takes to be a pseudomonas aeruginosa? the core genome of the opportunistic pathogen updated[END_REF]. Among the various benefits of sequence clustering are

• interpretability as for the classification of 16S ARN into OTU [START_REF] Hao | Clustering 16s rRNA for OTU prediction: a method of unsupervised bayesian clustering[END_REF],

• potential reduction of very large databases, i.e., too large to be processed in a relatively short time [START_REF] Rousk | Soil bacterial and fungal communities across a ph gradient in an arable soil[END_REF], or

• creation of non-redundant protein groups [START_REF] Suzek | Uniref: comprehensive and non-redundant uniprot reference clusters[END_REF] for instance. Moreover, clustering is also crucial for the discovery of new hidden variables underpinning the phenomena that are analysed. However, as noted by a number of researchers from the community of Machine Learning (ML), clustering may not be very reliable without an appropriate preliminary embedding of the data samples. The motto often quoted in ML is that high dimensional data are often too scattered for an off-the-shelf method to work properly. Several embeddings have been proposed in the literature. Some of them are better suited for supervised learning, such as the methods based on neural networks (e.g., auto-encoders) and some other methods are more suitable for unsupervised learning as is the case in the present work. Among many nonlinear embedding methods, the Laplacian Eigenmap [START_REF] Belkin | Laplacian eigenmaps and spectral techniques for embedding and clustering[END_REF] approach has been extensively studied from both the theoretical side and the application one [START_REF] Spielman | Spectral graph theory[END_REF]. Such methods have received a lot of attention and can be also constrained towards better postprocessing with a view towards improved clustering as shown in, e.g., [START_REF] Chrétien | A semi-definite programming approach to low dimensional embedding for unsupervised clustering[END_REF].

In the case study, our goal is to show the practical efficiency of a combination of the plain Laplacian Eigenmap approach with Gaussian Mixture based clustering. Our choice of this combination is mainly motivated by scalability constraints and the fact that both methods are state of the art in the Machine Learning community. The procedure is extremely natural and can be described as follows 1. Compute a similarity matrix between each couple of sequences. That is to say, a matrix W of size n × n (where n is the number of studied sequences), such that W i, j increases with the similarity of sequences i and j.

2. Apply the Laplacian Eigenmap [START_REF] Belkin | Laplacian eigenmaps and spectral techniques for embedding and clustering[END_REF] method to the matrix W . This method transforms the sequences in elements leaving in a given vectorial space, and whose positions in the space reflects well and illustrates in an richer way the sequence similarities.

3. Apply a clustering method to the points of the yielding space using a Gaussian mixture model [START_REF] Day | Estimating the components of a mixture of normal distributions[END_REF].

Our main contribution is twofold: we propose a ready to use Python package available online and we demonstrate the efficiency of the approach for the problem of clustering nucleotide sequences.

In particular, we tested the proposed methodology on a sample of one hundred ND3 genes (DNA sequences) from Platyhelminthes and Nematoda species that have been downloaded on the NCBI website1 . The classification produced by the proposed method has been compared with the phylogenetic tree of these species obtained by a likelihood maximization method using PhyML [START_REF] Guindon | PHYML online-a web server for fast maximum likelihood-based phylogenetic inference[END_REF]. According to this comparison, the clustering is consistent with both clades appearing in the phylogenetic tree and the NCBI taxonomy. More specifically, our clustering method perfectly separates the Nematoda and Platyhelminthes phyla. Among the Nematoda, we obtained a cluster for Trichocephalida order, another one for most of the species of the Spirurida order, and a last cluster for the remainder.

The plan of the paper is the following. The three stages of the proposed method are detailed in the next section, while an application example is provided in Section 3. The whole proposal is discussed in Section 4. Finally, this article ends with a conclusion section, in which the contribution is summarized and intended future work is outlined.

The Clustering Method

Design of the similarity matrix

The first step in the construction of a good embedding is the creation of a similarity matrix W . This matrix measures the similarity between every two sequences by providing a number between 0 and 1, the greater this number is, the most similar the sequences are.

We introduce here a way to build similarity matrices using the Needleman Wunsch "distance" [START_REF] Needleman | A general method applicable to the search for similarities in the amino acid sequence of two proteins[END_REF]. In order to do so, a multiple global alignment of the DNA sequences is run, for instance using MUSCLE (Multiple Sequence Comparison by Log-Expectation [START_REF] Edgar | MUSCLE: multiple sequence alignment with high accuracy and high throughput[END_REF])) software. Based on the results of this alignment, we can then define a first matrix M satisfying the following requirements: for all i, j ∈ [[1, n]], M i, j is the "Needleman-Wunsch distance" between sequence i and sequence j. More precisely, M can be computed, by evaluating the Needleman-Wunsch edit distance between each couple of aligned sequences, which is the reference distance when considering nucleotidic sequences. In practice, this can be done using the needle command from EMBOSS package [START_REF] Rice | EMBOSS: The european molecular biology open software suite[END_REF].

The matrix M is then divided by the largest distance value, so that all its coefficients are between 0 and 1. W can finally be obtained as follows:

∀ i, j ∈ [[1, n]], W i, j = 1 -M i, j ,
in such a way that W i, j represents the similarity between species i and j.

Laplacian Eigenmaps on W

The so-called Laplacian Eigenmaps [START_REF] Belkin | Laplacian eigenmaps and spectral techniques for embedding and clustering[END_REF]) is an original method of representation, in a k-dimension vector space, of a given matrix of similarity between complex objects (here, words on the {A,C,G,T} alphabet). In this space, points with real coordinates are close when their similarity is large. Indeed, increasing the dimension leads to a richer view of the similarities between different objects, onto which standard clustering techniques can be applied.

The first step is to create the normalized Laplacian matrix [START_REF] Chen | Resistance distance and the normalized laplacian spectrum[END_REF]:

L = D -1/2 (D -W )D -1/2 ,
where W is the similarity matrix defined previously and D is the degree matrix of W . That is to say, D is the diagonal matrix defined by:

∀i ∈ [[1, n]], D i,i = n ∑ j=1 W i, j .
L being symmetric and real, it is diagonalisable in a basis of pairwise orthogonal eigenvectors {φ 1 , ..., φ n } associated with eigenvalues 0 = λ 1 λ 2 ... λ n .

The Laplacian Eigenmaps consists in considering the following embedding function:

c k 1 (i) =      φ 2 (i) φ 3 (i)
. . .

φ k 1 +1 (i)      ∈ R k 1 ,
where c k 1 (i) is the coordinate vector of the point corresponding to the i th sequence.

In other words, the coordinate vector of the point corresponding to the i th sequence is constituted by the i th coordinate of each of the k 1 first eigenvectors, ordered according to the size of their eigenvalues. As stated previously, this cloud of points is a model of the DNA sequences, such that the proximity between two points increases (considering the Euclidean distance) with the sequence similarity.

The choice of the k 1 cutoff is a crucial issue and it is usually made as follows. The ordered eigenvalues are plotted, and we stop when the increase becomes negligible: the number of eigenvalues that are not discarded is k 1 . For instance, in our program, we have chosen to set k 1 as the first time the difference between the k th and (k + 1) th value is lower than 0.01.

Remark that W can be seen as a weighted adjacency matrix of a graph, where nodes are the DNA sequences while edges are labeled by the degree of affinity between their adjacent nodes. In the literature, the Laplacian matrix is often described as constructed from the weighted adjacency matrix of such a graph rather than constructed from a similarity matrix. These definitions are equivalent.

Gaussian Mixture based clustering

The final step is performed by applying Gaussian Mixture based clustering (GMM, [START_REF] Day | Estimating the components of a mixture of normal distributions[END_REF]) to point cloud. Gaussian Mixture Models belong to the class of unsupervised learning schemes [START_REF] Friedman | The elements of statistical learning[END_REF], and allows to distribute the data points into different clusters without a priori assumption about the clusters' interpretation. One of the very useful features of model based clustering is that the model allows to use information criteria in order to estimate the number of clusters using AIC [START_REF] Akaike | A new look at the statistical model identification[END_REF], BIC [START_REF] Schwarz | Estimating the dimension of a model[END_REF], or ICL [START_REF] Biernacki | Assessing a mixture model for clustering with the integrated completed likelihood[END_REF]. The mathematical assumption of a GMM is that the point cloud follows the distribution:

k 2 ∑ i=1 δ i N (µ i , Σ i ),
where k 2 is the number of clusters, δ i is the probability for a point to be in cluster i, and N (µ i , Σ i ) is the normal distribution of mean µ i and covariance matrix Σ i . GMM parameters are computed with the Expectation-Maximization (EM) algorithm [START_REF] Mclachlan | Finite mixture models[END_REF]. Notice that the EM algorithm may converge to singular distributions exponentially fast [START_REF] Biernacki | Degeneracy in the maximum likelihood estimation of univariate gaussian mixtures with EM[END_REF]. However, degenerate situations can be easily discarded and consistent estimators can be easly obtained in practice. Gaussian Mixture models are still a topic of current extensive research, both from the statistical perspective [START_REF] Wang | High dimensional expectationmaximization algorithm: Statistical optimization and asymptotic normality[END_REF] and the computational perspective [START_REF] Yi | Regularized EM algorithms: A unified framework and statistical guarantees[END_REF].

We have chosen to consider the Bayesian Information Criterion (BIC, [START_REF] Schwarz | Estimating the dimension of a model[END_REF]) to determine the number of clusters k 2 . The BIC, which is a criterion for model selection, is defined as follows:

BIC = -2ln(L) + ln(n)p,
where L is the likelihood of the estimated model, n is the number of observations in the sample, and p is the number of model parameters. This criterion allows us to select a model whose validity is based on a compromise between the value of the model likelihood (that we want to maximize) and the number of parameters to estimate (that we want to minimize). The likelihood of the model increases with k 2 as well as the number of parameters. The selected model will be by default the one that minimizes this criterion (but, in our software, the user can set manually, if needed, the desired number of clusters).

The clustering software

The Python program corresponding to the algorithm described in this section is freely available online at https://github.com/SergeMOULIN/clustering-tool-fornucleotide-sequences-using-Laplacian-Eigenmaps-and-Gaussian-Mixture-Models. Its main function provides a clustering either from a matrix of distances or a similarity matrix. Its prototype meets the following canvas: where:

• M is the matrix of distances between the genomic sequences. M can also be a matrix of similarities between the genomic sequences, by setting simil = TRUE (see below).

• refs, is the list of species references. Note that M and refs are the only mandatory arguments.

• simil is an optional Boolean argument. When simil = TRUE, then M is considered as a matrix of similarities between the DNA sequences. Otherwise it is a matrix of distances (simil = FALSE by default).

• nbClusters is the number of clusters desired by the user. By default, the program applies the BIC criterium to determine it.

• drawgraphs is an optional Boolean value to produce some graphics. If drawgraphs = TRUE, a two dimensional clustering of data is plotted (cf. Figures 4,5, and 6), as well as the graphical representation of similarities (as in Fig. 1).

• delta is the value used to select k 1 (i.e., the number of eigenvectors used in the Laplacian Eigenmaps). k 1 is the lowest value such that λ k 1 +1λ k 1 < delta. delta = 0.01 by default.

The output of Glust function, named "clustering" above, is a list of k 2 lists. Each list contains references to the species grouped in a particular cluster.

Illustration example on genomic data

The proposed method has been applied to a sample of 100 DNA sequences from the mitochondrial gene ND3 taken from various species of both Platyhelminthes and Nematoda. Figure 1 graphically displays the similarity matrix that has been obtained as described previously. As might be expected, the largest similarities are obtained on the diagonal, that is, when the sequences are compared to themselves. However, blocks seem to appear too in this representation, justifying the need to further investigate such similarities by applying our clustering method on these sequences. 4, to the one formed by the first and third eigenvectors in Figure 5, and to the plane formed by the second and the third eigenvectors in Figure 6. In these graphs, clusters 0, 1, 2, and 3 are represented in red, cyan, blue, and yellow respectively. A FASTA file has then be written, in which each nucleotide sequence has been labeled according to its taxonomy and its cluster number. The taxonomies have been found thanks to the efetch function (sub-package Entrez 2 , Python pack-Figure 5: GMM clustering in the plane formed by the eigenvectors 1 and 3 Figure 6: GMM clustering in the plane formed by the eigenvectors 2 and 3 age Bio). We then have used the online software PhyML (maximum likelihood method method for phylogenetic tree reconstruction) with default options [START_REF] Guindon | PHYML online-a web server for fast maximum likelihood-based phylogenetic inference[END_REF], to build a tree based on the same mitochondrial ND3 gene that we have used during clustering. The tree, whose leaves contain taxa names and cluster id, has been displayed using FigTree software [START_REF] Morariu | Automatic online tuning for fast gaussian summation[END_REF]. This tree is depicted in Figures 7 and8.

The efetch function provides 8 taxonomic levels for each species in our sample. In Figures 7 and8, for readability reasons, we only show the taxonomy between levels 4 and 6. Note first that this clustering perfectly separates Platyhelminthes and Nematoda phyla. Indeed Trematoda and Cestoda are two classes of Platyhelminthes. Cluster 1 corresponds exactly to the Platyhelminthes, while Clusters 0, 2, and 3 represent the Nematoda. Cluster 0 is only composed of Spirurida, it contains 10 of the 12 members of this taxon. More precisely, when considering the seventh taxonomic level, we found that Cluster 0 contains nine Filarioidea and one Thelazioidea, while the Spirurida that are not in this cluster Finally, in addition to recover taxonomy, the clustering agrees very well with the tree obtained via PhyML, as shown in Figures 7 and8. Note that the taxonomy, based on morphology and nuclear genome, fully agrees with the PhyML tree and our clustering, which are both based on the mitochondrial genome. This fact suggests that this mitochondrial gene evolves like the nuclear genome.

Discussion

Various options are possible to perform the analysis we have presented previously, some of them being listed hereafter.

Similarity matrix

The multiple global alignment step can be achieved using other software than MUSCLE. Among the most extensively used methods, we could have chosen MAFFT [START_REF] Katoh | MAFFT multiple sequence alignment software version 7: improvements in performance and usability[END_REF] for instance, as well as ClustalW or ClustalX [START_REF] Larkin | Clustal w and clustal x version 2.0[END_REF]. It is also possible to apply a pairwise alignment method like the Needleman-Wunsch algorithm [START_REF] Needleman | A general method applicable to the search for similarities in the amino acid sequence of two proteins[END_REF]. Moreover, we have chosen EDNAFULL scoring matrix, but other matrices are available to produce a score between two aligned sequences, like PAM or BLOSUM. Finally, instead of defining the similarity matrix W as W i, j = 1 -M i, j , it could be possible to consider W i, j = 1 M i, j or W i, j = e -M i, j . To find the best option among these possible choices, one can either test them on reference sequences on which the clusters to obtain are perfectly known, for instance by producing a laboratory-generated phylogeny. Another option can be to use a well-established phylogeny based on fossils morphology and molecular data. Finally, a third option can be to compute simulations of a set of species having a common ancestor. These three approaches have already been implemented to compare phylogenetic tree reconstruction tools. The first approach, for instance, has been applied in [START_REF] Hillis | Experimental phylogenetics: Generation of a know phylogeny[END_REF] on the bacteriophage T7 evolved in a laboratory. The second approach, for its part, has been applied in [START_REF] Cummings | Sampling properties of DNA sequence data in phylogenetic analysis[END_REF], [START_REF] Russo | Efficiencies of different genes and different tree-building methods in recovering a known vertebrate phylogeny[END_REF], and [START_REF] Zardoya | Phylogenetic performance of mitochondrial protein-coding genes in resolving relationships among vertebrates[END_REF], who used mammalian or vertebrate phylogeny to perform these comparisons. The last one was considered a lot of time, and summarised in [START_REF] Felsenstein | Phylogenies from molecular sequences: inference and reliability[END_REF], [START_REF] Huelsenbeck | Performance of phylogenetic methods in simulation[END_REF], and [START_REF] Nei | Phylogenetic analysis in molecular evolutionary genetics[END_REF].

Number of considered eigenvectors

The number of eigenvectors to keep is another point to investigate. As explained in Part 2.2, it is usually advised to check graphically when the increase of eigenvalues is reducing. In this article, we have chosen to consider k 1 such that δ = λ k 1 +1λ k 1 < 0.01. This criterion has led to k = 4 in the case study, which seems acceptable according to the considered taxonomy.

Some authors in the literature proposed to compute k 1 as the logarithm of n [START_REF] Matias | Notes de cours: Analyse statistique de graphes[END_REF]. It is also possible to consider a criterion related to the second derivative instead of the first one, by replacing the computation of δ by:

δ = (λ k 1 -λ k 1 -1 ) -(λ k 1 +1 -λ k 1 ).
The latter may be a good representative of the notion of inflection. Other approach can be considered to solve this problem, which is still an open one.

Number of clusters

We have chosen to consider the BIC [START_REF] Schwarz | Estimating the dimension of a model[END_REF] to determine the optimal number of clusters, which is a common choice for this type of problem. An alternative may be to use the Akaike Information Criterion (AIC, [START_REF] Akaike | A new look at the statistical model identification[END_REF]). The principle of calculating the AIC is the same as the BIC, since the goal is to maximize log-likelihood penalized by the number of parameters (or more precisely, to minimize the number of parameters to which the log-likelihood is subtracted). AIC formula is the following:

AIC = -2ln(L) + 2 × p,
where L is the likelihood of the estimated model and p the number of model parameters.

Indeed, BIC is "more conservative" than AIC. That is to say, the number of clusters obtained by BIC is lower or equal to the one obtained by AIC. In other words, BIC penalization is more important, and the choice between these two criteria can be dependent on how stringent the clustering is desired.

Conclusion

In this work, we have proposed a new method of nucleotide sequence clustering. This clustering is produced by a methodology combining Laplacian Eigenmaps with Gaussian Mixture models, while the number of clusters is set according the Bayesian Information Criterion. This methodology has been applied on 100 sequences of mitochondrially encoded NADH dehydrogenase 3. Obtained clusters are coherent with the phylogeny (gene tree obtained with PhyML) as well as with the NCBI taxonomy.

One possible extension for future work can be to investigate more deeply the impact of parameters in the obtained clusters. The effects of a modification in the similarity distance, in the manner to set the dimension of the space in Laplacian Eigenmaps, or in the number of desired clusters, will be systematically investigated. This clustering method will be applied in concrete problems related to genomics, for instance on coding sequences predicted on a set of bacteria, to determine the size of their core [START_REF] Alkindy | Finding the core-genes of chloroplasts[END_REF] and pan genome.

  clustering = GClust(M, refs, simil = False, nbClusters = 'BIC', drawgraphs = True, delta = 0.01)

Figure 1 :

 1 Figure 1: Similarity matrix

Figure 2 :

 2 Figure 2: Curve representing the first 14 eigenvalues

Figure 3 :

 3 Figure 3: Bayesian Information Criterion of the Gaussian Mixture Models

Figure 4 :

 4 Figure 4: GMM clustering in the plane formed by the eigenvectors 1 and 2

Figure 7 :

 7 Figure 7: First part of the phylogenetic tree (Platyhelminthes)

Figure 8 :

 8 Figure 8: Second part of the phylogenetic tree (Nematoda)

http://www.ncbi.nlm.nih.gov/

A package that provides code to access NCBI over the world wide web.


R M Chandima Ratnayake
email: chandima.ratnayake@uis.no

M Amarathunga

Quality Improvement of NLFM Manufacturing Process: Estimating Optimal Combination of Influencing Factor Levels

Keywords: Natural latex foam manufacturing, defects minimization, engineering robust design, quality deterioration factors

Natural latex foam mattresses (NLFMs) are manufactured using the latex extracted in its purest form of milky white liquid, which is tapped from the trunks of mature rubber trees. The natural latex foam mattress manufacturing (NLFMM) process undergoes several processing stages before the natural latex is converted into an ultra cushioning material with a wide range of firmness and comfort. Among the other processing steps, the gelling process has been found to play a significant role in controlling the quality of the final product, provided that quality raw materials have been supplied to the manufacturing plant. This manuscript suggests a methodology for estimating optimal levels of parameters that affect the gelling process, focusing on minimizing the influence on mattresses' surface quality deterioration. A case study has been performed in collaboration with one of the natural latex foam manufacturing plants to recognize main quality deterioration mechanisms and corresponding process parameters using the engineering robust design approach to establish the optimal combination of influencing factor levels.

Introduction

Natural latex foam mattress manufacturing (NLFMM) starts with the latex, which is extracted in its purest form when tapped from the trunks of mature rubber trees [START_REF] Nawamawat | Surface Nanostructure of Hevea Brasiliensis Natural Rubber Latex Particles[END_REF]. The extracted natural latex is then converted into an ultra cushioning material with a wide range of firmness and comfort, through heat, vacuum, and freezing. In general, the NLFMM processes follow one of the following approaches [START_REF] Jones | CHAPTER 1 -Historical Development of the World Rubber Industry[END_REF]: 1. Standard process: this is also referred to as the Dunlop process (Note: It is a less expensive process for NLFMM whilst producing a finished product that has a steadier feel); 2. Talalay process: this is the most advanced NLFMM process which manufactures latex mattress cores (Note: Latex cores manufactured using the Talalay process have been proven to be superior in comfort and durability with a greater range of firmness, i.e. from very soft to super firm).

Currently different kinds of categorizations are used to describe NLFMs [START_REF] Ryan | Latex as a Comfort Layer[END_REF]. For instance, there are three main kinds of categorizations in latex mattresses: 1. Pure latex (i.e. at least 20% natural and a blend of 80% synthetic); 2. Natural latex (at least 80% natural and a blend of 20% synthetic); and 3. 100% natural latex (i.e. 2% forming additives, 2% soaping agents and 96% latex from rubber trees) [START_REF] Ryan | Latex as a Comfort Layer[END_REF]. The 100% NLFMM process has been selected for the current study. Generally, natural rubber is very soft and elastic, whilst synthetic rubber provides good hardness to the foam.

The natural rubber is very dilute when it is tapped from a tree, having a rubber content of about only 30%. Hence, it is concentrated before use to above 61.5% solids which has been referred to as total solid content (TSC). Usually, 60.0% of TSC is rubber and the remaining 1.5% are compounds that are unique to natural latex (proteins, phospholipids, carbohydrates, amino acids) [START_REF] Sansatsadeekul | Characterization of Associated Proteins and Phospholipids in Natural Rubber Latex[END_REF]. The aforementioned unique ingredients play a significant role in explaining the behavior of natural latex [START_REF] Sansatsadeekul | Characterization of Associated Proteins and Phospholipids in Natural Rubber Latex[END_REF].

The initial preservation of the raw natural rubber latex and later for NLFM requires sending latex through several processing stages. In this context, controlling the quality of the final product is of significant importance and challenging. In particular, minimizing surface defects requires the identification of optimum settings of influencing factors. This manuscript first illustrates the results of a preliminary study, which have been utilized for the identification of influencing factors in relation to major surface defects. Then the manuscript suggests an engineering robust design based approach and framework to carry out experiments. Finally, it presents the results of the experiment (i.e. optimal combination of influencing factors).

Industrial Challenge and Preliminary Study

Industrial Challenge

The surface quality of mattresses is assessed based on the size and number of defects that are allowed to appear on the surface (top, bottom and sides) of the mattresses that are graded for the export market. Ideally a product is said to be of exportable grade when the product has a very uniform surface all around with no surface depressions or holes appearing. Fig. 1 illustrates the basic process of the natural latex foam manufacturing.

However, it is difficult to achieve the desired surface finish, especially due to the fact that there are inherent limitations present in the NLFMM process and technology as well as in the process of extraction of the main raw material (i.e. being a "natural or living" product). In the context of NLFMM process product quality, apart from the latex compounding step (i.e. related to the quality of the raw materials), the gelation is the next significant step that has a greater effect on controlling surface finish. Hence, the gelling process has been a subject for study. The main focus has been on developing a methodology for estimating the variables' set points (or levels) to improve surface finish.

Preliminary Study

A preliminary study has been carried out to investigate the different kinds of defects present in a natural foam latex mattress and their relationships to various influencing factors. Information has been gathered to obtain an overview about maturation time and different kinds of defects. Fig. 2 illustrates compounded latex maturation data.

Fig. 2 Compounded latex maturation data

Fig. 3 illustrates results of preliminary defect analysis for defects size less than 5x5 cm 2 . Fig. 4 illustrates results of preliminary defect analysis for defects size greater than 5x5 cm 2 . Table 1 illustrates the main surface defects vs. related codes which have been identified in a preliminary prioritization study of the surface finish. A fish bone diagram has been developed to understand the influence of different factors' interaction with the surface finish [START_REF] Ratnayake | Framework for Computing Machining Parameter Settings in CNC Machines: An Industrial Case Study[END_REF]. Using a fish bone diagram, the major influencing factors that affect the surface finish of natural latex foam mattresses have been identified and are illustrated in Fig. 5. Table 2 illustrates the parameters influencing quality deterioration that have been identified from the preliminary investigation. Hence, it is vital to develop a methodology to estimate the optimal combination of quality deterioration influencing factors in order to make the necessary improvements to surface quality in terms of reducing the number and size of the surface defects that appear on manufactured latex foam mattresses.

Methodology

Matrix Experiments using Orthogonal Arrays

An efficient way to study the effect of several control factors simultaneously is to plan matrix experiments using orthogonal arrays which have been introduced in the engineering robust design approach (ERDA) [START_REF] Phadke | Quality Engineering using Robust Design[END_REF][START_REF] Ratnayake | Small and Medium Enterprises Project Finance: Identifying Optimum Settings of Controllable Factors[END_REF]. A matrix experiment consists of a set of experiments which provides the possibility to change the settings of the various product or process parameters, which it is necessary to study, from one experiment to another [START_REF] Ratnayake | Use of Robust Design Technique in Job Shop Manufacturing: A Case Study of Die-Sinking Electro Discharge Machining[END_REF][START_REF] Taguchi | Quality Engineering through Design Optimization[END_REF]. For processes that involve many factors, experiments are conducted using special matrices called Orthogonal Arrays [START_REF] Mcewan | Taguchi Methods and Expert Systems in Fabrication Design[END_REF]. After conducting a matrix experiment, the data from all experiments are taken together and analyzed to determine the effects of the various parameters [START_REF] Ratnayake | Small and Medium Enterprises Project Finance: Identifying Optimum Settings of Controllable Factors[END_REF], [START_REF] Phadke | Quality Engineering using Robust Design[END_REF].

Analysis Approach

The following steps are adapted from the literature applying the ERDA in designing the experiments and finding the optimal internal vibration settings which give the best surface finish [START_REF] Phadke | Quality Engineering using Robust Design[END_REF].  Identify the challenge: In this study, the challenge is to investigate the optimal combination of influencing factor settings which minimizes the surface defects.

 Determination of the performance characteristic(s) and the measuring system:

The surface finish is evaluated by visual inspection and the use of appropriate measuring devices. According to the classification, the smaller the number of defects, the better the surface finishes.  Determination of the variables (parameters) affecting the performance characteristic(s): There are various factors affecting the NLFM surface finish (see Fig. 5). Considering the case study on "surface quality improvements for latex foam mattresses", the significant process parameters have been identified as: Polyethylene Glycol (A), raw latex maturation (B), compounded latex maturation (C), SSF (D), ZnO/DPG (E), mold temperature (F), ammonia content of latex (G) (see Table 2).

 Determination of the number of levels and values of the controllable variables (parameters):

In this case, only the controllable parameters are discussed. For example, Table 4 gives three levels for the variable raw latex maturation time (i.e. 30, 37 and 44 days). Only 18 experiments are needed to study the entire experimental parameters using the L18 orthogonal array.  Determination of loss function and the performance statistics: The "smaller-isbetter" (SMB) loss function is selected for calculating signal to noise ratios (S/N ratios) for surface defects [START_REF] Kamaruddin | Application of Taguchi Method in the Optimization of Injection Moulding Parameters for Manufacturing Products from Plastic Blend[END_REF] [see Equation [START_REF] Nawamawat | Surface Nanostructure of Hevea Brasiliensis Natural Rubber Latex Particles[END_REF]].

/ 10 ∑ (1)
where n = number of replications y ij = performance indicator value (i = 1,2…n and j=1,2,3…n).

 Conducting experiments and recording of results.  Analyzing data and selection of the optimum value of the controllable variables.

 Verifying the results.  Re-establishing and documenting the NLFMM process parameters.

Under the optimum set-points, the corresponding η opt is calculated using the additive model for factor effects (see [START_REF] Jones | CHAPTER 1 -Historical Development of the World Rubber Industry[END_REF] suggested by [START_REF] Phadke | Quality Engineering using Robust Design[END_REF].

/

where α = overall mean S/N ratio for surface defects count over all the possible combinations i,j,k,l,m.n = particular levels of each of the parameters which were selected (so in this model i,j,k,l,m,n must all take on one of the values 1, 2 or 3) = deviation from α caused by setting parameter "A" at level i (similarly, other terms in Equation ( 2) are defined) = error term.

The calculated represents the theoretical level of defect value at optimum settings found by experimentation. However, a verification experiment shall be per-formed to investigate the accuracy of the optimum settings. Fig. 6 provides a framework to illustrate the calculation and experimentation approach. Fig. 6 Framework for experimentation, estimation of best settings and verification

Results and Discussion

The levels of the factors to minimize the affect to surface finish of NLFM have been established based on the final analysis of the matrix experiment results and further discussions with a team of expert personnel. For the raw latex maturation time, level 3 (i.e. 44 days) has been shown to be the best level. However, due to the practical limitations of having such a long maturation in the latex storage tanks, the team has decided to purchase latex with 21 days' minimum maturation and issuing it for the manufacturing process after it reaches 30 days minimum.

For the compounded latex maturation time, levels 1 and 2 have indicated more or less the same effect on the defect code numbers 2, 13 and 15. Therefore, the team decided to adopt six hours minimum (within levels 1 and 2), while the raw latex maturation is 30 days minimum. For instance, if the raw latex maturation is closer to 44 days, then the compounded latex maturation has to be closer to level 1 (i.e. two hours).

For the SSF dosage, level 1 (0.9 pphr) has been shown to be the optimum level to reduce defect code number 2; however, its performance in reducing defect code number 13 is poor. Hence, the team decided to reduce the SSF dosage by 0.1 pphr from the present operating level.

For ZnO/DPG dosage, level 3 (i.e. 6 pphr) has indicated a greater effect in reducing defect code number 13; however, on average level 2 has a similar effect in reducing other defects, as well as having a good control over maintaining other parameters. Hence, the team has decided to increase the ZnO/DPG dosage by 0.1 pphr as it reduces defect code number 13.

For mold temperature, level 1 (i.e. 30 0 C) has the greatest effect in reducing defect code number 2. For defect code number 13, level 3 (i.e. 50 0 C) is indicated to be the best. Therefore, the team decided to adopt level 1 as the optimum level in order to reduce defect code number 2 to a greater extent.

For NH 3 content, the present operating level seems to be the best at controlling defects as well as other tested parameters. Also, for the factor pH of PEG, level 2 (10.5 pH) has been proven to be the best level for most of the tested parameters.

Conclusion

This manuscript proposes the use of the optimized design of experiments approach (i.e. ERDA) to estimate the optimal combination of factors influencing NLFM surface finish. The results indicate that the suggested approach is significantly efficient and effective in establishing the optimal combination of factor settings. Hence, it is possible to use the same approach in establishing the optimal combination of other settings by careful examination of the existing NLFMM.

Further research should be carried out to address the fuzziness present among the factor levels caused by the incorporation of experts' knowledge. This would enable further refined optimal factor level combinations to be established in an effective and efficient way.

Chemical dispersions 1 .Fig. 1

 11 Fig.1The process of the natural latex foam manufacturing

Fig. 3 Fig. 4

 34 Fig. 3 Defects distribution of natural latex foam mattresses (size less than 5×5 cm 2 ) Fig. 4 Defects distribution of natural latex foam mattresses (size larger than 5×5 cm 2 )

Fig. 5

 5 Fig. 5 Factors affecting the surface quality of natural latex foam mattresses (fish bone diagram) [Note: mechanical stability time (MST)]

Table 1 .

 1 Main surface defects vs. related codes

	Surface defect	Code
	Heat marks	2
	Loose skin	13
	Shrinkage marks/lake marks	15

Table 2 .

 2 Parameters influencing quality deterioration

	Symbol Quality deterioration influencing factor Units	1	Levels 2	3
	A	Raw latex maturation	days	30	37	44
	B	Compounded latex maturation	hours	2	8	14
	C	SSF dosage	pphr	0.9 1.5 2.2
	D	ZnO/DPG dosage	pphr	2	4	6
	E	Mold Temperature	0 C	30	40	50
	F	NH 3 content of latex	W/W % 0.18 0.22 0.28
	G	pH of PEG (mold releasing agent)	pH	7	10.5 12
	Parts of additive per hundred parts of rubber (pphr); Diphenyl Guanidine (DPG); PolyEthylene Glycol
	(PEG)


Demésio De Sousa

Rodrigo Franco Gonçalves

Marinalva Barboza

Oduvaldo Rose De Souza

Demésio Carvalho De Sousa

Rose Reis De Souza

Oduvaldo Vendrametto

Lean Production and Just in Time: A Case Study of the e-procurement Application

Keywords: ERP, B2B, Supply Chain

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

Introduction

Just in time (JIT) is an important philosophy in logistical activities, especially when it refers to lean production, initially of used by Toyota Motor Company in 70's. Mainly since 80's so far, the JIT philosophy which is one of the pillars of lean production has been used in several of companies segments with success such as: cost, time, reliability, quality and flexibility [1;4;10]. The variables that form the primary activities and the value chain has suffered alteration with the information technology introduction, it evolves machines, equipment, raw materials, supplies and other consumable items which are already commonly associated with primary activities [2; 9; 11].

The objective of this paper is to present the results gotten by an American multinational company (called XPTO Brazil, on this study), active in Brazilian market and it is a producer of food and beverages that through JIT philosophy, associated to an e-procurement tool, provided improvement in the purchasing process and company routing.

Backgrounds

Lean Production

Through a reverse logistical Lean Manufacturing and JIT study has realized other discoveries about philosophy contributions in areas related to logistics. The lack of integration between the key areas studied by authors that are Collecting, Inventory, Remanufacturing and Distribution. Through a long bibliographic review, the authors could get the JIT performance results in five sectors, such as: cost, speed, flexibility, quality and reliability. It's believed that JIT contribute for the process of remanufacturing as optimization of line production, involving the acquisition of resources and diagnosis of any activity in advance [3; 6; 13].

E-procurement

E-procurement is a buying application based on the Internet/Intranet or a place service that boosts the trade purchasing partners, maximize the commerce efficiency along the chain supplies and provides e-commerce strategy skills on the Internet. The solution of e-procurement facilitates the cooperative purchases through the Internet. According to the author, the tool has the power of turning into the purchasing process because it spreads in all steps identified by supply manager. E-procurement is the most revolutionary aspect of B2B and it will change completely and definitely the way of companies do business, replacing the physical process that involve trade. [2; 5; 8; 10]. The (table 1) presents some e-procurement types, its main models and features [START_REF] Kalakota | E-business 2.0: Roadmap for Success[END_REF]. Source: Adaptation by Kalakota and Robinson [START_REF] Liu | A review of structured document retrieval (SDR) technology to improve information access performance in engineering document management[END_REF].

2.3

Just in Time

Experiencing a post -WWII environment, Japan saw an opportunity to gain competitive advantage to optimize their processes through the use of quality tools and standardization, based on items of verification and control at all stages of the production process, generating customer value [1; 10]. JIT is used in a pull production system which produces only on demand, after the completion of an application in the amount and at the desired time, since it does not allow anticipation of purchases, production or transportation [4; 9; 11]. The stock is part of the assets of a company and thus directly influences the working capital. In this context, the JIT philosophy aims to meet demand instantaneously with perfect quality and no waste. Note in this context that the primary activities are essential to the achievement of logistics objectives are also those that contribute the largest share of logistics costs [1; 5; 12].

Methodology

Case study

The methodology used has been the application of a case study supported by a review of JIT philosophy and the application of an e-procurement platform in a specific view. The identification of weaknesses and strengths of XPTO Company was accomplished through the interviews with Supplies and Information Technology Directors, being guided by theme and goals as follow: Needing evaluation in order to determine the Planning, Warehousing, Handling and Storage Control, aiming at the service optimization and costs reduction through the concept of Lean Production, Just in Time and the application of an e-Procurement Platform. The specific objectives of the case study are: a) Evaluate the application of Just in Time and Lean Production concepts in XPTO Company Brazil identifying possible opportunities of improvement. b) Understanding the main techniques for storage sizing in order to attend business needs of a company, its warehousing and handling, focusing on Lean Production. c) Evaluate the results gotten through the application of e-procurement platform and its improvements in productive process and Just in Time. It has showed by the directors, reports, prints, graphs, sheets, floor plans and these documents have been used for the identification of weaknesses and opportunities of improvement and these ones served as a reference for the elaboration of proposals following the theme and goals pre-established and can be viewed in SWOT matrix and for being strategy information they will not be presented in their totality in this article.

On the documental analysis was possible to identify that: "XPTO Brazil firmly believes that the international trade strengths the stability and peace when it promotes the economic growing, the opportunities and the mutual understanding".

SWOT Analysis

The identification of strengths, weaknesses, threads and opportunities was the critical factor of success for the suitability of theme and proposed goals in this study, guided the incorporation of the best market practices and available technology following concepts and specific scientific methodology. a) Evaluate the application of Just in Time and Lean Production concepts at XPTO Brazil identifying possible improvements opportunities. • Strength: overview of all storages in movement in the company.

• Weakness: Absence of improvement actions and data analysis comparing them with scientific literature. • Opportunity: Integrating SAP-ERP system with e-procurement. b) Understanding the main techniques for a storage sizing in order to attend the business necessities of a company, its warehousing and movement, focusing on Lean Production. • Strength: ERP (Enterprise Resource Planning) System of routes managing and supplies. • Weakness: analysis and improvements lack using the data and information from ERP-SAP linked to scientific methodology. c) Evaluate the results have gotten through the e-procurement Platform Application and its improvement in productive process and in Just in time. • Strength: Emphasized only the improvement opportunity.

• Weakness: Lack of ERP (Enterprise Resource Planning) -SAP integration with a supplies module, being this also not contemplated in the organization core-business • Opportunity: implementation of an e-procurement Platform linking the ERP-SAP with supplies area.

The nature of strategy of the company business unit

Each business unit of XPTO Brazil follows the net and search international corporate strategy in order to provide the best conditions of understanding the benefits Logistics foundations, being that the business unit chosen was a distribution center of the company and the pilot project was also the unit studied for the e-procurement implementation, automatize the purchasing system from all over the group XPTO Brazil through an e-procurement Platform linking the ERP (Enterprise Resource Planning) -SAP with the supplies area, aiming at the lead time optimization, gains of competitiveness and cost reduction, being the strategy adopted to Brazil branch.

Results and Discussion

Through the analysis of the case study was possible to realize that the project of a warehouse should evaluate many factors in its interrelation with the performance and the company costs, in order to find the system that optimize the operations. The company studied (XPTO Brazil) showed layout organization failures, caused by the lack of planning from the top management, mainly related to the fleet control, management of distribution centers and optimization of purchasing process through the utilization of Information Technology.

The solution of Purchasing Service (Outsourcing) to the XPTO Brazil searched attending initially the purchasing necessities of: MRO (maintenance, repair and operations) for some of its plants. In the case of a success from pilot project will be expanded to other 9 existent plants. The activity objectives to reduce the charge of XPTO Brazil buyers and in the same time to provide a service with focused professionals in cost reduction and operational optimization regulated by a Service Level Agreement Index.

The (figure1) presents the first initial result got and shows the utilization of ERP in search of the excellence of the delivery level, excelling by the punctuality and the major customer satisfaction, the outcome presents an efficiency of 67% initially in a score from 0 to 100%. The result is provided by a system and it is based on references pre-established related to the planning and logistical control section focusing on JIT, where were noted several dispersed and geographically overlapping points. Next, it has been resized the routes, according to (figure 2), that optimized the routes in order to reduce the delivery distances purposed to respective sale outlets. The results departed from 1.032,77 meters to 588,31 meters, getting a reduction of 444,46 meters in a distance to be covered a month.

Fig. 2. Scenario routes restructured

It is noted as results gotten through the warehouse layout reorganization: At the beginning, the total available area for warehousing occupied 1.104 m 2 being 594 m 2 occupied by end products warehouse area and after the bibliographic research was implemented an improvement with the collaboration of a new layout in which the total warehouse area pass through disposing of 1.284 m 2 , being 714 m 2 intended to warehouse area according to the purchasing planning planned by e-procurement.

This way, the gain of physical space is of 180 m 2 and 120 m 2 through the Warehousing Physical Planning that provided a distribution more balanced of areas and installations allowing a possible cost reduction, as well as it avoided a regression on the flow of processing materials.

The (figure 3) presents the improvements after the suitability of control references, the improvement of efficiency reached to 90% validating one of the JIT objectives, after the utilization of ERP and the e-procurement platform in the search of delivery level, excelling for punctuality and the major customer satisfaction. The results are in accordance with the 3 objectives outlined in this case study because it resulted in a gain in efficiency of 13 % for the company searched. Note that the integration of SAP and e-procurement resulted in creating value for customers and stakeholders.

Conclusions

Lean Production and Just in Time philosophy associated to an e-procurement application has provided to the multinational company a remarkable improvement in its lead time, optimizing the return of purchasing process and the planned routing company. This structural change was supported by the adoption of the best practices in the supplies area, in other words, automatize the purchasing system of all the group of American multinational.

With the implementation of the e-procurement Platform linking ERP (Enterprise Resource Planning) SAP with the supplies area, aiming at the lead time optimization as possible to observe competitiveness gains in supplies area and the company passed through evaluating in a systemic way its business, adapting to the present view of Corporate Logistics and aligning its core business.

Fig. 1 .

 1 Fig. 1. Scenario of the areas and routes

Fig. 3 .

 3 Fig. 3. Scenario restructured areas and routes

Table 1 .

 1 Models of e-procurement

	Ecommerce templates	Main features
	Networks EDI Electronic Data Interchange.	Range of commercial and customer opinions. Simple transactional capabilities. Processing in series. Shift to value-added networks and reactive expensive way.
	Applications requisition	Quick Shopping for corporate employees. Automation of approval and
	Business-to-Employee	standardization of the requisition process. Provides the buyer manage-
	(B2E).	ment tool suppliers.
	Corporate procurement portals.	Better control over the procurement process and allows business rules of most companies are consistently implemented. Customize with prices negotiated in a multi-vendor catalog. Management cost analysis.
	Trade first generation.	Industrial content, jobs and news. New sales channel for distributors and manufacturers. Service bundling and catalogues.
	Trade second generation.	Automating the process of requesting and-order transactions. Discovery of suppliers, prices and products/services. Catalogues management and
		credit.
	Trade third generation.	Synchronized operations and satisfaction in real time. Transparency in the process leading to restriction of demand and supply chain.
		Alternative information for inventory.
	Industrial consortiums.	Next step in the evolution of corporate procurement portals.


Evandro Prestes Guerreiro

Pedro Luiz De Oliveira

Costa Neto

Ulysses Martins

Moreira Filho
email: moreiraf@uol.com

Multidisciplinary Management: model of excellence in the management applied to products and services

Keywords: Administration, Multidisciplinary Management, Model of Excellence, Quality Award

The Multidisciplinary Management is the guiding vision of modern organizations and the systems thinking which requires new approaches to organizational excellence and quality management process. The objective of this article is to present a model for multidisciplinary management of quality applied to products and services based on American, Japanese, and Brazilian National Quality Awards. The methodology used to build this model of Management Excellence starts from an analysis of the specific features of each Quality Award and the principle of a multidisciplinary administration, serving as support for the management of process excellence and results. The proposed model enables to manage organizational outcomes with sustainability, and to identify and place the task priorities in order of importance and urgency in the corporate environment. This strategy shall bring feedback for organizational results excellence.

Introduction

The management thought grounded in the cartesian model and in mathematical logic or evolutionary thesis is not enough to fill a space of contradictions that is beyond its philosophical approaches. This is a truth, even valuing the competent systematization of Scientific Theory made by engineer Frederick Winslow Taylor (1856Taylor ( -1915)), and adapted in Henri Ford's (1863-1947) factories focusing on operational efficiency in the industrial process, and Jules Henri Fayol (1841Fayol ( -1925) ) who founded the Classical Theory of Administration, to understand the administration process beyond than thought Taylor or Ford, seen with the strategic and tactical look of a director or manager [START_REF] Morin | The interaction between knowledge and education -Complexity: the seven knowledge and other essays[END_REF].

Fayol's contribution was decisive in shaping the thinking and the study of modern organizations, especially when he structured the four functions of management: Planning, Organizing, Directing and Controlling. Undeniably, the formal logic of cartesian thinking enabled the student, simplifying the complexity of the organizational structure at levels of management processes, making it easier to 2 modern teaching of managers about their practices, with what is known as a General Theory of Administration. On the other hand, what to do when the Administrative Thought can not diagnose the evolution of modern enterprise systems?

The answer may lie in the own management model. The word model, derived from the latin "modulus", leading to mold, shape, and although used in different contexts and different meanings, implies somehow the idea of the organizing and ordering of parts that make up a set. Corroborating this idea, a model is, by definition, an abstraction of reality, which may replace complexity for simplicity [START_REF] Have | Management Models[END_REF]. In other words, a model is and remains a tool that, when combined with the knowledge and experience and used properly, can help the organization to find solutions to old and new problems [START_REF] Ferreira | Management Models[END_REF].

Another vital feature of a management model is that it fosters innovation, in order to create competitive advantages in relation to its competitors, and this requires an organizational culture focused on learning and innovation, thereby reinforcing the valuable asset that an organization has, which is its human capital, as a result creating a healthy environment for knowledge creation [START_REF] Krogh | Facilitating the creation of knowledge: Reinventing Business with the Power of Continuous Innovation[END_REF].

The management model is the body of knowledge in an organization that enables the self-sustainability of the business, being essential to stimulate organizational learning, coupled with the development of specific competences able to operate a system that wins customers' preference, but also ensures excellence of the process as a whole and in a multidisciplinary way.

Objective

Presenting a quality management multidisciplinary model applied to products and services with the Management multidisciplinary model -MGM, based on the National Awards of the American, Japanese and Brazilian Quality.

Contextualization and Methodology

In this study, we selected three management models that are substantiated on the fundamentals and indicators of quality, that after each management cycle are subjected to the diagnosis of their processes and outcomes: Malcolm Baldrige National Quality Award (USA), National Quality Award (Brazil) and Japanese Quality Award (Japan), by presenting a deep learning in the way of "manage". It is important to say that all of the Quality Awards had its origins in 1951 with the establishment of the Deming Prize by the Japanese, honoring William Edwards Deming, dedicated to quality control focusing on the guaranteed 14 Deming points of quality, in the development of new products and the application that master's business philosophy.

The United States established the Malcolm Baldrige National Quality Award in 1987 with the Public Law 100-07. The American model of quality in the 90s also served as the basis for the proliferation of management models in all Southeast Asia. In Japan this award was called Japanese Quality Award

The Brazilian Program of Quality and Productivity was formalized in 1986 with the aim of preparing Brazilian companies to a new reality: globalization. As a result of this movement the National Quality Foundation, was created and launched the Brazilian National Quality Award in 1991.

Table 1 shows the main characteristics of the three models that supported the proposed management model. The methodology used to build up the Model of Excellence in Management applied to products and services, was developed in three steps:

Step1 -Bibliography Research: Analyze the specific characteristics of each Quality Award and the principle of a Multidisciplinary Management, working as a support for the management of excellence in the processes and results.

4

Step 2-Multidisciplinary Process: Integrating each component of the system considered as quality indicators, starting of the Action Method, that substantiate the strategic thought, based on the specific technology of each product and / or service, which drives to excellence of the result.

Step 3 -Person as manager: Enabling and maximizing the technical and management skills that enable systemic understanding of the Management Multidisciplinary Model, applied to the development of the objective conditions of quality control in the results in high performance corporate environments.

Theoretical background

Frederick W. Taylor (1856Taylor ( -1915)), in his work "Principles of Scientific Management" [START_REF] Taylor | The Principles of Scientific Management[END_REF], published in 1911 observed that the production of each worker could be maximized by at least two thirds of his capacity, however was not reached due to a kind of systematic vagrancy. To resolve this issue, he thought that workers should be seen as instruments of production and, as such, should be monitored and controlled to achieve effectiveness and the operational efficiency of the organization. Taylor signaled that "the basic unit of scientific management was the function and construction of a formal structure required first establishing objectives and then dividing the work into smaller units (simple tasks), which would be placed as a coordinated system (the workers tasks rationalization)" [START_REF] Silva | Theories of Administration[END_REF]. The production process must be integrated and collaborative among the stakeholders that, directly or indirectly, make up the corporate system. Therefore, suggests that teamwork with the leader and other workers is responsible for organizational success.

Henri Fayol (1841Fayol ( -1925)), in turn, complements the observations of Taylor when developing a study on the organizational structure, seeking to understand how the relationship between the corporate sectors can interfere with productivity. As show "Fayol believed in general and unique principles of sound administration and the role that scientific prediction and the proper methods of administration would play in improving business results" [START_REF] Sobral | Administration -Theory and Practice in the Brazilian context[END_REF]. The same authors continue their analysis with presentation of the six interrelated operational groups proposed by Fayol: technical operations, sales, financial, safety, accounting and administration operations.

Management is one of the functions of the company, but differs from the others by its specificity and macro importance. "None of the other functions is responsible for formulate the overall program of action of the company, build its social body, coordinate efforts, harmonize the actions " [START_REF] Fayol | Industrial and General Administration[END_REF]. The purpose of Fayol was to structure the organization as a whole, stating that the functions of management are: predicting, organizing, commanding, coordinating and controlling. Unlike Taylor and Fayol, who presented a prescriptive theoretical orientation, Max Weber [START_REF] Weber | Economy and Society: Fundamentals of comprehensive Sociology[END_REF] formulated his theoretical approach as an ideal model from a descriptive approach to organizational structure, assuming that organizations function as a closed system, and the bureaucracy is their ideal and most efficient form of organization which, even being impossible to be found in practice, seeks to address the corporate whole and focuses on the internal environment of the organization, in detriment of its external environment.

Multidisciplinary Management and its management model

A multidisciplinary approach is grounded in disciplinarity, which organizes scientific knowledge, establishing the division and specialization of labour [START_REF] Nicolescu | Education and Transdisciplinarity[END_REF], as proposed by Taylor, Fayol and Weber in their studies, aiming to respond to the complexity of the diversity of the investigated object, but preserving their autonomy and border compared to other areas of knowledge, using specific theories, language and techniques.

The Multidisciplinary Management considers that the focus on the task allowed Taylor managerial mechanisms to be revolutionary at his time, increasing productivity, reducing fatigue of the workers and optimizing the economic viability of the process, reaching more profitable results in the production line, therefore, an unique contribution to organizations. On the other hand, the task is part of a much larger purpose, since it is the middle of the process, the start and end of the activity needing to be properly controlled and supervised, what requires the contributions of Fayol and Weber to organize and structure the stages that precede and exceed the task itself.

This model understand that the present corporate environment information enables the production of knowledge, needed to establish a quality management and organizational learning. Moreover, like any model, the development of the method of intervention requires the kind of technology and strategy to be employed for reaching the benefit of the best result and the people involved in the process.

To manage in a multidisciplinary way, according to the MMM model, means to be enough technically competent to manage people to become autonomous, have efficient processes, efficient procedures, visionary plans, political diversity of interests and new administrative paradigms, able to guide the creation of new models of technical competence and excellence in organizational management. Each dimension, which integrates multidisciplinary management, challenges the ability of the organizational manager, not only as a strategist, but mainly as an entrepreneurial leader in administrative and technical tools of corporate management, implemented though what we call 6P system:

1. Persons: form the intellectual capital of the whole entire organizational system, prepared to address specific and general problems in the field of knowledge management and corporate learning;

2. Process: stages of development of productive organization, composed of input and consumption, from tangible and intangible resources needed to produce the intended result; 6 3. Procedures: techniques and methods applied in the production process, with the objectives of the tasks interpretation, understanding the goals of results and optimizing resources to achieve operational efficiency of production;

4. Plans: strategic systematization of corporate sustainability, from the drafting stages of increasingly customized output in terms of economic efficiency, productivity and profitability, assessing the trends in the consumer market and innovating solutions to practical problems of the clients;

5. Policies: ability to understand and manage the diversity of interests involved in the organizational process, creating real conditions for disseminating the shared investments, objectives, resources, capabilities, partnerships, strategic alliances and intellectual capital;

Discussion

Multidisciplinary Management helps to better understand the process of applying Multidisciplinary Management Model -MMM, guiding decision making about the use of the most appropriate administrative tools to a particular management problem, such us to develop a product or service, or to adopt a strategic choice to better position the organization in the market.

The main contribution of the Malcolm Baldrige National Quality Award was challenging U.S. companies in the "Quest for Excellence" and "Excellence in Performance" to compete with Japanese products.

The National Quality Award in Brazil led to the beginning of a change in Brazilian entrepreneurial mindset, influenced the curricula of the Administration courses in the country since 1995 and brought a new managerial vision to Brazilian managers and enterprises owners.

The Japanese Quality Award contributes to strengthen broader approaches to the management improvement activities within the industrial community in Japan. It also provided the impetus for the creation of local awards systems and is currently being pursued in ten regions, including Fukui, Nigata, Chiba, Mie and Tochigi.

The proposed model is aligned with the core values and concepts recommended by the Malcolm Baldrige National Quality Award (USA), National Quality Award (Brazil) and Japanese Quality Award (Japan).

Conclusions

Linear administration proposed by disciplinarity gradually turns to the search for a Multidisciplinary Management, able to update and innovate models and management practices, responding to the demands of the complexity of the Information Age.

The study about the National Quality Awards of U.S., Japanese, and Brazilian served to identify common points of each award, which strengthen each other, but also possible to observe weaknesses of cultural context, requiring the difference of the management style, according to nationality or the origin of each person. This observation was consolidated at the MMM model proposed in this research, placing the center of the system, the person as manager.

The proposed Multidisciplinary Management Model enables managing organizational outcomes and sustainability, identifies and places the task priorities in order of importance and urgency in the corporate environment. This strategy brings a feedback of excellence to organizational results.

6 .

 6 Figure1: Multidisciplinary Management Model -MMM. (Source: authors, 2014)

Promotes the strengthening of management best practices, facilitates internal communication and serves to better understand the system of management, planning, training and judgment to customers, as well as their strategies and action plans focused on the market.

	Quality	Brief historic	Core values and concepts	Criteria	Purpose
	award	settings
		Created in 1987 by	Systems perspective;	1-Leadership;
	Malcolm Baldrige National Quality Award	Public Law 100-07 based on the Deming Prize, under the supervision of Deming, Juran and Feigenbaum. It is	Visionary leadership; Focus on the future; Managing for innovation; Agility; Organizational and personal learning; Valuing workforce members and	2-Strategic planning; 3-Customer focus; 4-Measurement, analysis, and knowledge management;
	(USA) [5]	administered by by	partners; Customer-driven	5-Workforce focus;
		NIST -National	excellence; Social	6-Process management;
		Institute of Standards and Technology	responsibility; Management by facts;	7-Results.
			Focus on results and
			creating value.
		Created in 1991	Systemic thinking;	1-Leadership;
		based on the	Network actuation; Agility;	2-Strategic planning;
	National Quality Award (Brasil) [6]	Malcolm Baldrige Award. it is administered by FNQ-National Quality Foundation.	Fundamental decisions; Organizational learning; Innovation; Visionary leardership; Vision of the future; Customers and	3-Customer focus; 4-Information and knowledge; 5-Workforce focus 6-Process management
			market knowledge; Social	7-Results.
			responsibility; Valuing
			people and the culture;
			Process oriented; Value
			generation.

The Management Excellence Model proposed by the National Quality Foundation, uses PDCL cycle (Plan, Do, Check, Learn), to meet the needs and expectations of its customers, which must be identified, understood and used, so that products can be developed, creating the need to conquer and retain them, acting to contribute to the Socio Environmental development. Japan Quality Award (Japan) [7]

	Created in 1995	Customer -driven quality;	1-Leadership of senior	It is a tool for changing the
	based on the	Leadership; Process-	leaders;	way of managing creating a
	Malcolm Baldrige	oriented; Creating	2-Social responsibility of	culture for managing
	Award, incorporating	"Knowledge"; Agility;	management;	competitivity. Looks for
	Japanese practices. It	Partnership and fairness.	3-Understanding and	companies that continue to
	is administered by		responding to customer	create value through
	JPC -SED -		and Market needs;	continuous process of self-
	Japanese Productivity		4-Strategic planning and	innovation, to transform their
	Center for Socio-		deployment;	global management systems in
	Economic		5-Improving employer and	customer-oriented structures.
	Development.		organizational
			capacities;
			6-Customer value
			creating process;
			7-Information
			management
			8-Activity results.

Table 1 : Models of the Quality Awards. (Source: author, 2014)

 1

Evandro Prestes Guerreiro,[START_REF] Morin | The interaction between knowledge and education -Complexity: the seven knowledge and other essays[END_REF] Pedro Luiz de Oliveira Costa Neto,[START_REF] Morin | The interaction between knowledge and education -Complexity: the seven knowledge and other essays[END_REF] Ulysses Martins M. Filho


Gert Zülch
email: gert.zuelch@gefora-beratung.de

Evaluating Human Work in the Digital Factory -A New German Guideline

Keywords: Human models, ergonomics, workplace design, physical stress, evaluation

Over a period of several years a Guideline Committee of the Association of German Engineers (VDI) engaged in the development of a part of a guideline for computer-aided modelling and ergonomic evaluation of working people in digital factory tools. The subject of this part is to document the state of the art in analysis, evaluation and assessment of stresses and strains through work tasks. Broken down according to the separate aspects of engineering mechanics, it looks at existing anthropometric and physiological functionalities of evaluating human labour, with a distinction made between those that are already required as standard and those that are still considered to be optional and are only applied in a few procedures. It appears that the evaluation methods used often lead to different assessments, and that some necessary functions are not yet realized. Further progress is therefore required from an ergonomic perspective.

VDI Guidelines for Representing Humans in the Digital Factory

The digital factory already has a proven way of securing the planning of parts manufacturing and assembly systems. In 2008, the Technical Committee "Digital Factory" within the Association of German Engineers (VDI) started with the publication of a series of guidelines for digital factory planning. The first part of this guideline series, VDI Guideline 4499 Part 1 [1], looks at the basics of digital factory planning. The other parts of this guideline series, each of which is developed by a separate Guideline Committee, involved special tools, such as the digital factory operation. Currently a VDI Guideline Committee is dealing with the ergonomic analysis, evaluation and assessment of stresses and strains of working people through work tasks with tools of the digital factory. Digital human models were first developed in the mid-1980s as progress was made with the processing of graphical data. Today, digital human models are one of the fundamental tools used in connection with the digital factory. But the graphical representations and the available ergonomic evalua-tions differ substantially from each other in some cases. After more than 25 years of developing digital human models, the question we now face is which human models come into consideration for certain ergonomic aspects, and what limitations the procedures still have.

Figure 1 shows an exemplary virtual representation of a manual assembly system. The new guideline part focuses on the methods available in Germany. Stresses and strains caused by the working environment will be the subject of a future part of the guideline. The current Guideline Committee is composed of representatives from science and software companies as well as industrial users. The draft VDI Guideline 4499 Part 4 [START_REF]Entwurf:2012-04: Digitale Fabrik -Ergonomische Abbildung des Menschen in der Digitalen Fabrik; Digital Factory -Ergonomic representation of humans in the digital factory[END_REF] was published in 2012. After processing of objections, the final version will appear along with an English translation in mid-2014. The new guideline part is different to VDI Guideline 3633 Part 6 [4], already published in 2001, in that it deals with the "Representation of human resources in simulation models". This guideline part is based on a longer-term perspective of human resources from one shift up to many months. In contrast, the focus of the new VDI Guideline 4499 Part 4 is on the dynamic analysis of operations in the second and minute range, and on the evaluation of static working situations.

Functionalities of Ergonomic Human Models

The structure of the Guideline 4499 Part 4 is based on the different aspects of engineering mechanics, namely geometry, kinematics, statics and dynamics. While from an ergonomic perspective the first two aspects are part of anthropometric design, the latter two constitute physiological work design. For each of these aspects, underlying functionalities are listed that an ergonomic human model should include as well as those that are optional but are present in at least one of the tools available in Germany. The following gives an overview of the characteristic options for modelling and ergonomic evaluation and assessment.

2.1

Geometric Analysis

The geometry of the work system first and foremost concerns the spatial layout of the workplace with furnishings, as well as the geometry of work objects, workpiece carriers and equipment. Here it is apparent that much of the data used in CAD models has no relevance for ergonomic issues, for example tolerances and contact areas between the internal parts of a pre-assembled workpiece.

The second aspect concerns the dimensions of the human body. The statistical percentage values from existing standards and data collections suffice for this purpose, although these usually relate to an unclothed human body. There is much less standardized data on the appropriate clothing, particularly in the case of protective clothing, which represents a problem when examining a person's freedom of movement.

Another problem is the variability of the human body depending on posture. There are only standards relating to the hip or seat width of the human body. It is highly likely that the recently concluded series of studies conducted as part of the SizeGermany project [START_REF] Gröber | Deutsche wachsen weiter -aber eher in die Breite[END_REF] will provide a new set of underlying data. Although these studies are aimed at the clothing industry, they will certainly influence the standardization of body dimensions in other fields.

Kinematic Analysis

Kinematic analysis and evaluation relates on the one hand to the zones of movement of human limbs and also to the time required to carry out these movements. The joints of the human body and the way the limbs move present a particular problem. This is because of the range of relative movements between the surfaces of the limbs and sliding elements, as well as the relationships between the limbs involved in a movement. One example of this is the way in which the shoulder follows when working with your hands above your head. Assuming inflexible limbs and hinge or pointshaped joints, these movements can be approximated using engineering kinematics. These technical conveniences result in a certain degree of inaccuracy in the movement paths and reaching distances when compared with real body movements. Movement paths can be calculated using forward or inverse kinematics. There are a number of ways to calculate a movement path from a starting point to a destination, for example by applying the principle of minimizing joint excursion based on having the joints at a comfortable angle. But in many cases it is not yet clear which way is the most appropriate one.

Another problem is the speed at which the body motions are carried out. The current state of the art is that the necessary time evaluation is carried out on the basis of predetermined time systems or standard times. Figure 2 visualizes a manual operation together with the Gantt chart representation of the operation sequence and a time evaluation by means of MTM-UAS.

However, the time evaluation by means of a system of predetermined times can only serve as an approximation, for example if movement paths encounter obstacles and loads have to be transported. It is known that the load on the muscles (and therefore also the time required to complete the movement) depends not only on the horizontal reaching distance but also on the angle as well as the starting distance and destination distance from the body. Adding the vertical excursion of the hand/arm system as a third dimension further modifies the amount of time required as we would expect. The paths followed by the various parts of the human body and the time required to perform these movements are usually measured by means of motographic recording using real test subjects. However, applying this to human modelling processes requires synthesizing algorithms that allow the parameterized calculation of movement paths and their time requirements. Biomechanical approaches from some research laboratories aimed at developing humanoid robots and in the field of sports science show how this can be done.

Static Analysis

From a static perspective, the movements of the human body are subject to internal and external forces and torques. Therefore, a distinction is made between posture when working (static work posture) and isometric holding work, i.e. of a weight. It may be necessary to further specify the static work down to hand, finger, leg and foot forces and the corresponding torques.

One particular problem is presented by postures that are imposed by the physical dimensions of the work situation. This is especially the case if parts of the body are resting on parts of the work system. Although it is possible in principle to calculate the state of equilibrium for the imposed posture, but this is not done in existing procedures. Instead, posture is represented as a drawing taking into account the geometric properties of the human body. Furthermore, this does not take into account the deformation of the body's surface.

There are a number of methods for analysing, evaluating and assessing human static posture and holding work based on kinematic assumptions or even practical approaches. They include the OWAS method (Figure 3) developed in Finland as well as the Guidance Characteristic Method that is widely used in Germany. Interactive calculation forms for the latter method are available on the internet. It also takes into account the time required for a particular static posture or holding task in the form of frequencies per shift. Both methods provide an assessment of static work and indications of the need for redesign measures, albeit in different levels of detail. However, a dynamic assessment is not carried out as static work is only analysed at a specific point in time that is known to the user to be critical.

The static methods include the NIOSH load capacity method from the US and the RULA method from the UK. Based on the evaluation results, an assessment of the predicted stress on individual limbs is made using a traffic light assessment. The methods mentioned also take external forces into account, allowing both static posture and holding work to be evaluated.

It is apparent that Anglo-American evaluation methods dominate international human modelling procedures, while tools developed in Germany are typically not integrated into standard digital factory planning procedures. For example, the VDI method of determining load limits, which has been known in Germany for years, is available as a stand-alone computing procedure but not as a tool for the digital factory. It should be noted that the various methods for evaluation of static working in extreme cases can lead to different assessments of operations [7, pp. 114].

Dynamic Analysis

In the course of digital factory planning, dynamic aspects of human modelling are generally represented by taking into account the frequency or duration of movements under the influence of external forces and torques. The maximum possible forces and torques are reduced by reduction factors such as gender, age, training and frequency of movement. This principle is followed by the Guidance Characteristic Method, for example, for lifting and carrying, pushing and pulling, as well as repetitive manual work operations.

In other applications, the metabolic energy consumption is calculated based on systems of predefined loads. These kinds of approaches date back already to the 1920s. They can be combined with a system of predetermined times, and presented in table form. For example, the calculation of the metabolic energy consumption in accordance with Spitzer, Hettinger and Kaminski is included in the EKIDES procedure. However, this method is not a part of digital factory procedures used in Germany. At least the American human models JACK and JILL also include a prospective evaluation of human fatigue and recovery according to the formulae developed by Rohmert.

On the other hand, methods for calculating the dynamic stresses on human subjects to the influence of forces and accelerations are a largely undeveloped field with regard to digital factory planning. Military applications have been known already since the mid-1980s, especially with regard to aircraft piloting, which have been further developed for crash investigations in the field of automotive development. Another field of application can be found in sports science, for example the procedures being developed in Germany by Chemnitz University of Technology.

Other aspects of human modelling have been developed in Germany by the Karlsruhe Institute of Technology alongside the development of humanoid robots: If one hopes to make the movements of robots as humanlike as possible it is necessary to analyse human motions. Not only does this involve analysing the geometric properties and paths of motion of humans, but also the mass of their limbs and their inertia properties. The aim is then to synthesize motion paths, i.e. generating movements in accordance with the principles of forward dynamics or also inverse dynamics (analogous to forward kinematics and inverse kinematics). However, the principles according to which the motion paths should be generated, such as the principle of minimum torque, are yet largely unclear. These approaches therefore still require validation in comparison to real motion paths.

However, dynamic applications from the field of factory planning are not currently known. For example, while it is conceivable that the stress on the spine when walking on a floor with suspension properties could be evaluated, this has not yet been tested, and certainly not integrated into the digital factory procedures. Comparable applications are well known from the design of automobile seats and merely require transferring in order to be able to evaluate work stresses or even work aids provided by the suspension properties of a work platform.

Anatomical human models that take muscles, sinews and tendons into account in addition to limbs and joints show the way in this regard. The work of MIRALab at the University of Geneva in Switzerland deserves a particular mention in this regard. Figure 4 shows an example of the Danish human model AnyBody when getting in and getting out of a passenger car. The aggregated muscle activity is shown as a function of the handle height.

3

Need for Further Development

The discussion of digital human models by the current VDI Guideline Committee based on the various aspects of engineering mechanics not only revealed the extent to which ergonomic aspects are already incorporated into various tools of the digital factory, but also their limitations. While anthropometric design can be seen as covered as a matter of standard in a wide area, there are still a number of questions with regard to physiological work design. It is apparent that evaluation options from the German-speaking world are rare in commercial tools. It is also proving particularly disadvantageous in operating practice that evaluation methods developed for the same ergonomic aspects sometimes produce different assessments. There continue to be deficits regarding the analysis of collisions between model elements, both for rigid bodies and particularly for flexible objects and their deformation as a result of collisions.

The examples given here show that the modelling of humans in digital factory tools is still far from adequate for the purpose of conducting ergonomic evaluations and assessments at a comprehensive level of work systems that only exist in a virtual form. The risk-assessment of future work systems in the interest of prospective occupational health and safety also poses a number of methodical questions. These mainly pertain to the evaluation and assessment of successive load cycles for a single type of stress and for several types of stress working simultaneously, both issues requiring further fundamental ergonomic research.

Muscle activity envelope

Movement

Grip position

Fig. 1 .

 1 Fig. 1. Visualization of an assembly system [Software: 2]

Fig. 2 .

 2 Fig. 2. Workplace layout and time evaluation with MTM-UAS [3, p. 18, transl; Software: 2]

Fig. 3 .

 3 Fig. 3. Evaluation of overhead work using the OWAS method [3, p. 20; Software: 6]

Fig. 4 .

 4 Fig. 4. Aggregated muscle activity during entry and exit from a car [3, p. 22; Software: 8]

Acknowledgement

In his role as coordinator of the work presented here in summary, the author would like to thank all the members of the VDI Guideline Committee and everybody, especially from software companies, who have contributed their support.