Applying Constraint Databases in the Determination of Potential Minimal Conflicts to Polynomial Model-Based Diagnosis

Model-based Diagnosis allows the identification of the parts which fail in a system. The models are based on the knowledge of the system to diagnose, and may be represented by constraints associated to the components. The variables of these constraints can be observable or non-observable, depending on the situation of the sensors. In order to obtain the potential minimal diagnosis in a system, an important issue is related to finding out the potential minimal conflicts in an efficient way. We consider that Constraint Databases represent an excellent option in order to solve this problem in complex systems. In this work we have used a novel logical architecture of Constraint Databases which has allowed obtaining these potential conflicts by means of the corresponding queries. Moreover, we have considered Gröbner Bases as a projection operator to obtain the potential minimal conflicts of a system. The first results obtained on this work, which are shown in a heat exchangers example, have been very promising.Ministerio de Ciencia y Tecnología DPI2003-07146-C02-0

Developing a labelled object-relational constraint database architecture for the projection operator

Current relational databases have been developed in order to improve the handling of stored data, however, there are some types of information that have to be analysed for which no suitable tools are available. These new types of data can be represented and treated as constraints, allowing a set of data to be represented through equations, inequations and Boolean combinations of both. To this end, constraint databases were defined and some prototypes were developed. Since there are aspects that can be improved, we propose a new architecture called labelled object-relational constraint database (LORCDB). This provides more expressiveness, since the database is adapted in order to support more types of data, instead of the data having to be adapted to the database. In this paper, the projection operator of SQL is extended so that it works with linear and polynomial constraints and variables of constraints. In order to optimize query evaluation efficiency, some strategies and algorithms have been used to obtain an efficient query plan. Most work on constraint databases uses spatiotemporal data as case studies. However, this paper proposes model-based diagnosis since it is a highly potential research area, and model-based diagnosis permits more complicated queries than spatiotemporal examples. Our architecture permits the queries over constraints to be defined over different sets of variables by using symbolic substitution and elimination of variables.Ministerio de Ciencia y Tecnología DPI2006-15476-C02-0

NMUS: Structural Analysis for Improving the Derivation of All MUSes in Overconstrained Numeric CSPs

Models are used in science and engineering for experimentation, analysis, model-based diagnosis, design and planning/sheduling applications. Many of these models are overconstrained Numeric Constraint Satisfaction Problems (NCSP), where the numeric constraints could have linear or polynomial relations. In practical scenarios, it is very useful to know which parts of the overconstrained NCSP instances cause the unsolvability. Although there are algorithms to find all optimal solutions for this problem, they are computationally expensive, and hence may not be applicable to large and real-world problems. Our objective is to improve the performance of these algorithms for numeric domains using structural analysis. We provide experimental results showing that the use of the different strategies proposed leads to a substantially improved performance and it facilitates the application of solving larger and more realistic problems.Ministerio de Educación y Ciencia DIP2006-15476-C02-0

¿Qué hacen y qué entienden los estudiantes y profesores de física cuando usan expresiones diferenciales?

En un trabajo previo realizamos una clarifi cación del uso del cálculo diferencial y determinamos un conjunto de indicadores de lo que sería una adecuada comprensión del concepto de diferencial en la física. Guiados por las conclusiones de ese trabajo, presentamos ahora el análisis que hemos realizado de la enseñanza habitual, más concretamente sobre lo que hacen y entienden los estudiantes y profesores cuando usan el cálculo diferencial en las aplicaciones físicas. Después de enunciar y fundamentar la hipótesis de partida, y de presentar el diseño experimental elaborado para someterla a prueba, se muestran y discuten los resultados más importantes que hemos obtenido al aplicar ese diseño con una amplia muestra de profesores de bachillerato y estudiantes de bachillerato y universidad. Esos resultados confirman la ausencia de todos los indicadores de comprensión de la diferencial, poniendo de manifiesto el uso meramente algorítmico del cálculo y las consecuencias negativas que ello tiene para el aprendizaje de la física.One of our previous works explained the use of differential calculus and determined a series of indicators of what could be considered as the appropriate understanding of the concept of differential in physics. Following the conclusions reached in the aforesaid work, this article now analyses common teaching, and more precisely what teachers and students do and understand when applying differential calculus in physics. The present work exposes and justifi es our first hypothesis and presents the experimental design elaborated to test it, and then puts forward the most relevant results registered when applying that design on a large sample of secondary school teachers and secondary school and university students. Attained results prove the absence of all understanding indicators of the differential and highlight the merely logarithmical use made of calculus, as well as the negative impact it has on learning physics

A Hybrid Water Distribution Networks Design Optimization Method Based on a Search Space Reduction Approach and a Genetic Algorithm

This work presents a new approach to increase the efficiency of the heuristics methods applied to the optimal design of water distribution systems. The approach is based on reducing the search space by bounding the diameters that can be used for every network pipe. To reduce the search space, two opposite extreme flow distribution scenarios are analyzed and velocity restrictions to the pipe flow are then applied. The first scenario produces the most uniform flow distribution in the network. The opposite scenario is represented by the network with the maximum flow accumulation. Both extreme flow distributions are calculated by solving a quadratic programming problem, which is a very robust and efficient procedure. This approach has been coupled to a Genetic Algorithm (GA). The GA has an integer coding scheme and variable number of alleles depending on the number of diameters comprised within the velocity restrictions. The methodology has been applied to several benchmark networks and its performance has been compared to a classic GA formulation with a non-bounded search space. It considerably reduced the search space and provided a much faster and more accurate convergence than the GA formulation. This approach can also be coupled to other metaheuristics

Obstacles to Mathematization in Physics: The Case of the Differential

The process of the mathematization of physical situations through differential calculus requires an understanding of the justification for and the meaning of the differential in the context of physics. In this work, four different conceptions about the differential in physics are identified and assessed according to their utility for the mathematization process. We also present an empirical study to probe the conceptions about the differential that are used by students in physics, as well students’ perceptions of how they are expected to use differential calculus in physics. The results support the claim that students have a quasi-exclusive conception of the differential as an infinitesimal increment and that they perceive that their teachers only expect them to use differential calculus in an algorithmic way, without a sound understanding of what are they doing and why. These results are related to the lack of attention paid by conventional physics teaching to the mathematization process. Finally, some proposals for action are put forward

Efecto de la confianza en la lealtad y el eWOM en las comunidades virtuales de marca.

La confianza en la marca y en la Comunidad Virtual de Marca (CVM) pueden contribuir a la generación de lealtad a la marca y eWOM positivo. Sin embargo, no han sido muchos los estudios empíricos que han incluido ambos tipos de confianza en la evaluación de los resultados de las CVM. Por lo tanto, este trabajo tiene como objetivo explorar cómo la confianza en la marca y la confianza en la comunidad influyen en la lealtad y en el eWOM. Para ello se emplearon datos procedentes de una encuesta realizada a usuarios de CVM que fueron analizados mediante la técnica PLS. Los resultados confirman que la confianza en la marca influye en la lealtad y en el eWOM tanto directamente, como indirectamente a través de la confianza en la CVM. Además, la lealtad favorece la generación de eWOM. Las implicaciones para la práctica de marketing son comentadas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Run-Time Auditing for Business Processes Data Using Constraints

Business processes involve data that can be modified or up dated by various activities. These data must satisfy the business rules associated to the process. These data are normally stored in a rela tional database, and hence the database has to be analyzed to determine whether the business rules can be satisfied. This paper presents a framework including a run-time auditing layer where the correctness of a database can be analyzed at different check points of a business process according to the data flow. It provides an early detection of incorrect action on stored data. Furthermore, in or der to manage the current business rules, the use of the constraint pro gramming paradigm is proposed and the enlargement of the Constraint Database Management Systems to support business rulesJunta de Andalucía P08-TIC-04095Ministerio de Ciencia y Tecnología TIN2009-1371

Fault diagnosis in databases for business processes

Business processes involve data that can be modified or updated by various activities. These data must satisfy the business rules associated to the process. As the information treated in a business process tends to be extensive, data are normally stored in a relational database, and hence the database has to be analyzed to determine whether the business rules are satisfied and what values are incorrect. This paper proposes the use of model-based diagnosis in the business processes scenario. This scenario combines business processes, business rules, relational databases and where the faults are the instances of the variables introduced by the users. These considerations make it necessary to introduce a new way for representing the model, and the design of new algorithms to solve it. This model provides a means for the detection of incorrect tuples of different tables of the database by avoiding the analysis of the full database. Furthermore, in order to manage the current business rules, the use of a constraint paradigm is proposed and by using Max- CSPs to isolate incorrect values.Junta de Andalucía P08-TIC-04095Ministerio de Ciencia y Tecnología TIN2009-1371