Non-linear projection to latent structures

PhD ThesisThis Thesis focuses on the study of multivariate statistical regression techniques which have been used to produce non-linear empirical models of chemical processes, and on the development of a novel approach to non-linear Projection to Latent Structures regression. Empirical modelling relies on the availability of process data and sound empirical regression techniques which can handle variable collinearities, measurement noise, unknown variable and noise distributions and high data set dimensionality. Projection based techniques, such as Principal Component Analysis (PCA) and Projection to Latent Structures (PLS), have been shown to be appropriate for handling such data sets. The multivariate statistical projection based techniques of PCA and linear PLS are described in detail, highlighting the benefits which can be gained by using these approaches. However, many chemical processes exhibit severely nonlinear behaviour and non-linear regression techniques are required to develop empirical models. The derivation of an existing quadratic PLS algorithm is described in detail. The procedure for updating the model parameters which is required by the quadratic PLS algorithms is explored and modified. A new procedure for updating the model parameters is presented and is shown to perform better the existing algorithm. The two procedures have been evaluated on the basis of the performance of the corresponding quadratic PLS algorithms in modelling data generated with a strongly non-linear mathematical function and data generated with a mechanistic model of a benchmark pH neutralisation system. Finally a novel approach to non-linear PLS modelling is then presented combining the general approximation properties of sigmoid neural networks and radial basis function networks with the new weights updating procedure within the PLS framework. These algorithms are shown to outperform existing neural network PLS algorithms and the quadratic PLS approaches. The new neural network PLS algorithms have been evaluated on the basis of their performance in modelling the same data used to compare the quadratic PLS approaches.Strang Studentship European project ESPRIT PROJECT 22281 (PROGNOSIS) Centre for Process Analysis, Chemometrics and Control

What is emerging? Understanding urbanisation dynamics in BRICS countries through a geographical approach, the case of Russia and South Africa

International audienc

Early Repayment of Loans Under EU Law: The Lexitor Judgment

Recent changes in EU law provide flexibility and protection to consumers, facilitating early repayment of loans, when the consumer is no longer interested in continuing a credit relationship. From an economic point of view, early repayment of loans should be facilitated, because it allows money that is no longer needed to be put to other desirable uses. Under current EU law, as recently interpreted in the Lexitor judgment by the Court of Justice of the European Union, upon early repayment of a loan, consumers can obtain a pro-rated reimbursement of all the up-front and recurring costs of the loan, including origination fees and ancillary service costs. In this brief article, we take a critical look at the current EU approach to this issue, suggesting that, while the legislature made the pragmatic choice in permitting partial reimbursement of up-front costs, this leads to several economic inefficiencies that can ultimately hurt the consumer. Repayment of up-front costs, and of any other sunk cost associated with the creation of the loan, can lead to a suboptimal mix of lending contracts. Some consumers could, in fact, take out a lower interest rate long-term credit, even though they may only need a short-term loan, and this would create a disadvantage for the overall class of consumers. In order to actually protect the economic interest of consumers and carry out the intent of the legislature, we conclude that the up-front costs for non-mandatory ancillary services (such as brokerage fees, etc.) should not be included in the costs that are eligible for reimbursement in the event of early repayment of the loan. By excluding these costs, consumers will not be incentivized to overconsume such services, minimizing the negative externalities imposed on other consumers

Aportación al estudio de prácticas mortuorias durante el Período de Desarrollos Regionales. Entierros en vasijas utilitarias del sector central del valle Calchaquí (Salta, Argentina)

In this paper we analyze published and unpublished information on sub-adults´ burials in urns from settlements of the Regional Development Period (9th - 15th centuries) in central Calchaquí Valley, Salta, Argentina. We deepen into information about late children´ burials in ordinary vessels, the use of certain words and ideas, and about signs related to mortuary practices

Protecting privacy amid questions of economic efficiency and egalitarianism

This paper aims to analyze theories developed both in favor and against privacy protection according to current practices in the West. In the paper, we will examine economic justifications for privacy protection as defined by American economists and jurists, as well as the advantages to be derived by a possible elimination of said protection. Moving beyond existing economic theories, this piece develops a new economic idea, wherein privacy protection is warranted when an individual becomes interested in another's habits for a specific reason: to root out different behaviors in that person by observing a behavior that is correlated with those behaviors. Imagine the scenario of a worker who is also a soccer player, who is not competitive on the job, and is a team player, when he plays soccer, with his co-workers. The two facts, one of loving his own soccer team, and second, of not being competitive in the workplace are expressions of the same human attitude, or of a certain aspect of his personality. The employer is interested in finding out if this worker plays soccer in order to identify a lack of competitiveness on the job, and perhaps to assign him more menial tasks. The employer wishes to know the worker's interest in soccer in order to deduce therefrom a second circumstance: non-competitiveness in the workplace. Thus if regulating others' conduct is not forbidden, the worker, in order not to be found out, will no longer play soccer; he will suffer a loss in terms of his personal welfare, while the employer, on the other hand, will gain nothing, having discovered nothing. From this comes a different justification for privacy protection. In the paper, however, we note that privacy protection is a tool for encouraging equality or, in pejorative terms, egalitarianism. Behind the privacy “screen,” indeed, everyone appears in shades of gray. Privacy protection makes individuals indistinguishable. In terms of inter-personal relationships, this means a “veil” of ignorance, with all its attendant costs. Therefore, it is possible that the economic justifications defined by those in favor of privacy protection should be put aside in favor of transparency among individuals

De la mobilité à l’accessibilité : l’évolution des transports comme ressources dans la ville sud-africaine

Les transports en commun ont constitué un des rouages des processus d’exclusion socio-spatiale des populations ségrégées pendant l’apartheid, en conditionnant notamment les mobilités vers les ressources urbaines. Outil de contrôle, le devenir de ces services à l’époque post-apartheid questionne aussi bien la redistribution des ressources, l’accessibilité permise par les réseaux de transport que les modalités de la planification sous l’égide d’un gouvernement métropolitain fort. En distinguant les conditions de mobilité et d’accessibilité des populations aux ressources dans la métropole du Cap et leur rôle dans le maintien des inégalités, il est alors possible d’appréhender dans quelle mesure les transports peuvent constituer une ressource dans la ville pour promouvoir l’inclusion sociale

Pratiques d'une métropole émergente par les usagers des transports en commun, le cas du Cap, Afrique du Sud

La ville du Cap, à l'image des autres villes sud-africaines, se développe selon le double modèle de la ville post-apartheid et de la ville émergente. Cette évolution implique des changements démographiques, sociaux et politiques importants, particulièrement visibles dans l'espace urbain en raison du spatial mismatch qui continue de caractériser la ville et d'isoler les populations des townships des opportunités de la ville, en particulier des bassins d'emplois. Cela se traduit par des mobilités longues et fastidieuses pour les employés des catégories sociales inférieures, alors que le système de transport en commun demeure encore largement hérité de la période d'apartheid. L'étude des mobilités des maids permet d'éclairer ces mutations socio-spatiales, notamment par l'observation de leur pratique du transport, des stratégies qu'elles déploient pour se déplacer et de leur expérience de l'espace du transport.The city of Cape Town, like other cities in South Africa, is developing towards the dual model of the post-apartheid city and the emerging city. This evolution involves important demographic changes, as well as social and political. Those changes are especially visible in the urban space due to the spatial mismatch which still characterizes the city and keeps on isolating township dwellers from benefiting the city's opportunities, especially in terms of labour. It results in long and fastidious mobilities for low-income populations, whereas the transport system is still largely inherited from the apartheid era. The study of the maids' mobilities enables to enlighten these socio-spatial changes, especially through the observation of their practice of the transport network, the strategies they adopt to move and through their experience of the transport space