Automated nonlinear system modelling with multiple neural networks

This article discusses the identification of nonlinear dynamic systems using multi-layer perceptrons (MLPs). It focuses on both structure uncertainty and parameter uncertainty, which have been widely explored in the literature of nonlinear system identification. The main contribution is that an integrated analytic framework is proposed for automated neural network structure selection, parameter identification and hysteresis network switching with guaranteed neural identification performance. First, an automated network structure selection procedure is proposed within a fixed time interval for a given network construction criterion. Then, the network parameter updating algorithm is proposed with guaranteed bounded identification error. To cope with structure uncertainty, a hysteresis strategy is proposed to enable neural identifier switching with guaranteed network performance along the switching process. Both theoretic analysis and a simulation example show the efficacy of the proposed method.

Characterization of Transmission Losses

In this paper, characterizing transmission losses according to their origin is carried out. Transmission loss is decomposed into three components. The first is due to the current flow from generators to loads. The second is due to the circulating current between generators. The third represents the contribution of network structure and controls to increasing or decreasing transmission losses. Analytical proofs of the proposed loss decomposition are presented along with methods of allocating each component to the parties contributing to it. Illustration on simple dc and ac systems is presented. Results of application of the proposed method compared with other methods are also presented.

The predictive science of community ecology

Body mass measures provide a tantalizing tool for explaining both variation in emergent community-level patterns and as a mechanistic basis for fundamental processes such as metabolism, consumption and competition. The unification of body mass, abundance and food web (ecological network) structure in community ecology is an effective way to explore future scenarios of environmental change. However, constraints over the availability of data against which to validate model predictions limit the application of size-based approaches. Here, I explore issues over the use of body size for predicting interaction strengths and hence the dynamics of natural ecosystems. The advantages, disadvantages, opportunities and limitations of such approaches are explored. © 2011 The Author. Journal of Animal Ecology © 2011 British Ecological Society.

Urothelial cancer gene regulatory networks inferred from large-scale RNAseq, Bead and Oligo gene expression data

BACKGROUND: Urothelial pathogenesis is a complex process driven by an underlying network of interconnected genes. The identification of novel genomic target regions and gene targets that drive urothelial carcinogenesis is crucial in order to improve our current limited understanding of urothelial cancer (UC) on the molecular level. The inference of genome-wide gene regulatory networks (GRN) from large-scale gene expression data provides a promising approach for a detailed investigation of the underlying network structure associated to urothelial carcinogenesis.

METHODS: In our study we inferred and compared three GRNs by the application of the BC3Net inference algorithm to large-scale transitional cell carcinoma gene expression data sets from Illumina RNAseq (179 samples), Illumina Bead arrays (165 samples) and Affymetrix Oligo microarrays (188 samples). We investigated the structural and functional properties of GRNs for the identification of molecular targets associated to urothelial cancer.

RESULTS: We found that the urothelial cancer (UC) GRNs show a significant enrichment of subnetworks that are associated with known cancer hallmarks including cell cycle, immune response, signaling, differentiation and translation. Interestingly, the most prominent subnetworks of co-located genes were found on chromosome regions 5q31.3 (RNAseq), 8q24.3 (Oligo) and 1q23.3 (Bead), which all represent known genomic regions frequently deregulated or aberated in urothelial cancer and other cancer types. Furthermore, the identified hub genes of the individual GRNs, e.g., HID1/DMC1 (tumor development), RNF17/TDRD4 (cancer antigen) and CYP4A11 (angiogenesis/ metastasis) are known cancer associated markers. The GRNs were highly dataset specific on the interaction level between individual genes, but showed large similarities on the biological function level represented by subnetworks. Remarkably, the RNAseq UC GRN showed twice the proportion of significant functional subnetworks. Based on our analysis of inferential and experimental networks the Bead UC GRN showed the lowest performance compared to the RNAseq and Oligo UC GRNs.

CONCLUSION: To our knowledge, this is the first study investigating genome-scale UC GRNs. RNAseq based gene expression data is the data platform of choice for a GRN inference. Our study offers new avenues for the identification of novel putative diagnostic targets for subsequent studies in bladder tumors.

Learning Bounded Tree-Width Bayesian Networks via Sampling

Learning Bayesian networks with bounded tree-width has attracted much attention recently, because low tree-width allows exact inference to be performed efficiently. Some existing methods [12, 14] tackle the problem by using k-trees to learn the optimal Bayesian network with tree-width up to k. In this paper, we propose a sampling method to efficiently find representative k-trees by introducing an Informative score function to characterize the quality of a k-tree. The proposed algorithm can efficiently learn a Bayesian network with tree-width at most k. Experiment results indicate that our approach is comparable with exact methods, but is much more computationally efficient.

Heuristics for the Critical Node Detection Problem in Large Complex Networks

Complex networks have recently attracted a significant amount of research attention due to their ability to model real world phenomena. One important problem often encountered is to limit diffusive processes spread over the network, for example mitigating pandemic disease or computer virus spread. A number of problem formulations have been proposed that aim to solve such problems based on desired network characteristics, such as maintaining the largest network component after node removal. The recently formulated critical node detection problem aims to remove a small subset of vertices from the network such that the residual network has minimum pairwise connectivity. Unfortunately, the problem is NP-hard and also the number of constraints is cubic in number of vertices, making very large scale problems impossible to solve with traditional mathematical programming techniques. Even many approximation algorithm strategies such as dynamic programming, evolutionary algorithms, etc. all are unusable for networks that contain thousands to millions of vertices. A computationally efficient and simple approach is required in such circumstances, but none currently exist. In this thesis, such an algorithm is proposed. The methodology is based on a depth-first search traversal of the network, and a specially designed ranking function that considers information local to each vertex. Due to the variety of network structures, a number of characteristics must be taken into consideration and combined into a single rank that measures the utility of removing each vertex. Since removing a vertex in sequential fashion impacts the network structure, an efficient post-processing algorithm is also proposed to quickly re-rank vertices. Experiments on a range of common complex network models with varying number of vertices are considered, in addition to real world networks. The proposed algorithm, DFSH, is shown to be highly competitive and often outperforms existing strategies such as Google PageRank for minimizing pairwise connectivity.

Principe de finalité, protection des renseignements personnels et secteur public : étude sur la gouvernance des structures en réseau

Thèse réalisée en cotutelle avec l'Université de Montréal et l'Université Panthéon-Assas Paris II

EPDM/CIIR Blends: Compatibility, Morphology and Physical Properties

A detailed study of the blends of ethylene-propylene-diene rubber (EPDM) and chlorobutyl rubber (CIIR) is proposed in this study. These blends may find application in the manufacture of curing diaphragms/curing envelopes for tire curing applications. EPDM possesses better physical properties such as high heat resistance, ozone resistance, cold and moisture resistance, high resistance to permanent defonnation, very good resistance to flex cracking and impact. Because of the low gas and moisture penneability, good weathering resistance and high thermal stability of CIIR, blends of EPDM with CIlR may be attractive, if sufficient mechanical strength can be developed. Although a lot of work has been done on elastomer blends, studies on the blends of EPDM and CIIR rubbers are meagre. Hence in this investigation it is proposed to make a systematic study on the characteristics of EPDM and CIIR rubber blends.The mechanical and physical properties of an elastomer blend depend mainly on the blend compatibility. So in the first part of the study, it is proposed to develop compatible blends of EPDM with CIIR. Various commercial grades of ethylenepropylene- diene rubber are proposed to be blended with a specific grade of chlorobutyl rubber at varying proportions. The extent of compatibility in these blends is proposed to be evaluated based on their mechanical properties such as tensile strength, tear strength and ageing resistance. In addition to the physical property measurements, blend compatibility is also proposed to be studied based on the glass transition behavlour of the blends in relation to the Tg's of the individual components using Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). The phase morphology of the blends is also proposed to be investigated by Scanning Electron Microscopy (SEM) studies of the tensile fracture surfaces. In the case of incompatible blends, the effect of addition of chlorosulfonated polyethylene as a compatibiliser is also proposed to be investigated.In the second part of the study, the effect of sulphur curing and resin curing on the curing behaviour and the vulcanizate properties of EPDM/CIIR blends are planned to be evaluated. Since the properties of rubber vulcanizates are determined by their network structures, it is proposed to determine the network structure of the vulcanizates by chemical probes so as to correlate it with the mechanical properties.In the third part of the work, the effect of partial precuring of one of the components prior to blending as a possible means of improving the properties of the blend is proposed to be investigated. This procedure may also help to bring down the viscosity mismatch between the constituent e1astomers and provide covulcanization of the blend.The rheological characteristics and processability of the blends are proposed to be investigated in the last part of the study. To explore their possible applications, the air permeability of the blend samples at varying temperatures is proposed to be measured. The thermal diffusivity behaviour of EPDM/CIlR blends is also proposed to be investigated using novel laser technique. The thermal diffusivity of the blends along with the thermal degradation resistance may help to determine whether the blends are suitable for high temperature applications such as in the manufacturing of curing envelope.

Studies On Vulcanization, Rheology And Reinforcement Of Natural Rubber Latex With Special Reference To Accelerator Combinations, Surface Active Agents And Gamma Irradiation

In the present work, studies on vulcanization, rheology and reinforcement of natural rubber latex with special reference to accelerator combinations, surface active agents and gamma irradiation have been undertaken. In vulcanization, the choice of vulcanization system, the extent and mc-zie of vulcanization and network structure of the vulcanizate are important factors contributing to the overall quality of the product. The vulcanization system may be conventional type using elemental sulfur or a system involving sulfur donors. The latter type is used mainly in the manufacture of heat resistant products. For improving the technical properties of the products such as modulus and tensile strength, different accelerator combinations are used. It is known that accelerators have a strong effect on the physical properties of rubber vulcanizates. A perusal of the literature indicates that fundamental studies on the above aspects of latex technology are very limited. Thereforea systematic study on vulcanization, rheology and reinforcement of natural rubber latex with reference to the effect of accelerator combinations, surface active agents and gamma irradiation has been undertaken. The preparation and evaluation of some products like latex thread was also undertaken as a part of the study. The thesis consists of six chapter

Fat-Tree Routing for Transit

The Transit network provides high-speed, low-latency, fault-tolerant interconnect for high-performance, multiprocessor computers. The basic connection scheme for Transit uses bidelta style, multistage networks to support up to 256 processors. Scaling to larger machines by simply extending the bidelta network topology will result in a uniform degradation of network latency between all processors. By employing a fat-tree network structure in larger systems, the network provides locality and universality properties which can help minimize the impact of scaling on network latency. This report details the topology and construction issues associated with integrating Transit routing technology into fat-tree interconnect topologies.

Social Media Analytics: Trust and Power

In this lecture for a second year interdisciplinary course (part of the curriculum innovation programme) We explore the scope of social media analytics and look at two aspects in depth: Analysing for influence (looking at factors such as network structure, propagation of content and interaction), and analysing for trust (looking at different methods including policy, provenance and reputation - both local and global). The lecture notes include a number of short videos, which cannot be included here for copy-write reasons.

La adopción de un enfoque de trabajo en red: implicaciones en torno al proceso estratégico de las organizaciones

En el mundo actual el enfoque del proceso estratégico es una variable que cada vez va tomando un mayor peso e incidencia en las decisiones de los directores de empresa, sin embargo, poco se ha estudiado sobre esta variable al ser adoptado por los nuevos modelos de cooperación empresarial en las organizaciones. Es por esta razón que esta investigación busca esclarecer la aplicabilidad de las metodologías y herramientas utilizadas en la planeación estratégica de una empresa en una red, además de servir como un primer acercamiento a los aspectos más importantes en la planeación estratégica de una red.

De lo micro a lo macro prudencial: Un análisis de la supervisión bancaria desde la econometría espacial

La crisis que se desató en el mercado hipotecario en Estados Unidos en 2008 y que logró propagarse a lo largo de todo sistema financiero, dejó en evidencia el nivel de interconexión que actualmente existe entre las entidades del sector y sus relaciones con el sector productivo, dejando en evidencia la necesidad de identificar y caracterizar el riesgo sistémico inherente al sistema, para que de esta forma las entidades reguladoras busquen una estabilidad tanto individual, como del sistema en general. El presente documento muestra, a través de un modelo que combina el poder informativo de las redes y su adecuación a un modelo espacial auto regresivo (tipo panel), la importancia de incorporar al enfoque micro-prudencial (propuesto en Basilea II), una variable que capture el efecto de estar conectado con otras entidades, realizando así un análisis macro-prudencial (propuesto en Basilea III).

El trabajo en equipo en el Proceso Administrativo y de Compras en OPL Carga de Bucaramanga

El proceso administrativo y de compras de OPL Carga tiene algunas falencias entre ellas: fallas en la Comunicación entre el personal operativo, no se realizan llamadas internas usando con frecuencia el email, produciendo la saturación de solicitudes las cuales terminan sin ser resueltas en cuanto a roles se refiere, no hay enfoque de procesos en vista que no se tiene claras las tareas de cada cargo, adicionalmente no hay claridad en los subprocesos, perjudicando el proceso con el aumento de costos, pérdida de tiempo, las responsabilidades de los funcionario no todas las veces se ejecutan en el tiempo asignado, el liderazgo compartido presenta ambigüedades. Objetivos: Definir el trabajo en equipo en el proceso administrativo y de compras en OPL carga de Bucaramanga. La investigación que a realizar es de tipo descriptivo, busca descubrir las falencias o características que permiten diseñar y desarrollar un modelo de solución para los problemas del equipo de OPL Carga S.A.S. Materiales y métodos: La investigación efectuada es de tipo descriptivo, el objetivo es definir el modelo del trabajo en equipo y describir las falencias en el proceso administrativo y de compras en OPL carga de Bucaramanga, que permitan obtener un diagnóstico integral que conlleve a la implementación de estrategias de solución. Resultados: Se identificaron las falencias en los siguientes aspectos: Variable comunicación, rendimiento, destrezas complementarias, propósito significativo y meta específicas de los funcionarios en OPL carga sección administrativa. Conclusiones: El modelo de trabajo en equipo que OPL aplica es jerárquico, en el que se ofrece estabilidad, seguridad, se toman decisiones en forma piramidal, mediante la planeación de tareas, la colaboración, igualdad y respeto por los miembros, trabajando en pro de la solución de problemas. Se construyó un plano conceptual que permitió exponer la interpretación que la estudiante tiene de las teorías, investigaciones y antecedentes válidos para la comprensión del problema investigado. Área comunicacional: Coordinar acciones tendientes para que los funcionarios respondan a tiempo los emails atenientes a su trabajo. Área condiciones de trabajo: Clarificar y diseñar las reglas de comportamiento al interior de los equipos de trabajo que redunden en el mejoramiento del mismo y la búsqueda de soluciones oportunas. Área metas específicas: Procurar mediante auditorías el cumplimiento de las metas y objetivos propuestos por cada equipo de trabajo.

El valor dinamitzador dels projectes d'innovaci?? educativa de caire institucional

Els projectes d'innovaci?? educativa promoguts per les administracions p??bliques es poden convertir en eines poderoses de dinamitzaci?? d'un centre escolar. La implementaci?? del Projecte d'immersi?? en angl??s a la tardor i el Projecte ARCE al CEIP Blai Bonet (Santany??), mitjan??ant un conjunt de tasques interdisciplin??ries i interc??cliques, ha servit per promoure el treball en equip; una estructura educativa en xarxa; una comunitat d'aprenentatge i un sentit compartit de pertinen??a a l'escola. Aquestes finalitats s'han anat assolint a partir de la planificaci?? i aplicaci?? d'activitats significatives per als alumnes en relaci?? amb cinc blocs tem??tics convergents en els dos projectes educatius: Aigua, Terra, Flora, Fauna i Impacte hum?? de l'entorn mediambiental (la comarca, l'illa, la pen??nsula Ib??rica, el planeta Terra). Explicarem la nostra experi??ncia educativa i el valor dels projectes d'innovaci?? com a for??a impulsora per millorar les compet??ncies b??siques dels alumnes i per generar pr??ctiques de col??laboraci?? entre l'equip docent, la comunitat educativa i les institucions de l'entorn.