Programming Without Refining

To derive a program for a given specification R means to find an artifact P that satisfies two conditions: P is executable in some programming language; and P is correct with respect to R. Refinement-based program derivation achieves this goal in a stepwise manner by enhancing executability while preserving correctness until we achieve complete executability. In this paper, we argue that it is possible to invert these properties, and to derive a program by enhancing correctness while preserving executability (proceeding from one executable program to another) until we achieve absolute correctness. Of course, this latter process is possible only if we know how to enhance correctness.Comment: In Proceedings Refine 2018, arXiv:1810.0873

[Cp*Ru]-catalyzed selective coupling/hydrogenation

International audienc

Enhancing the SVDD accuracy in Intrusion Detection Systems by removing external voids

This work aims to improve the accuracy of the SVDD-based Intrusion Detection Systems. In this study we are interested by approaches using only one-class classification, namely the class of normal user sessions. Sessions are modeled by vectors of points in a finite features space. The goal of using the SVDD in anomaly detection is to find the hypersphere with a minimal volume that encloses the entire scatter of points (i.e. the normal sessions). This paper discusses the general case where the shape of the scatter is arbitrary. In this case some voids can occur between the scatter and the boundary of the hypersphere, and mainly cause a distortion of the data description that reduces the accuracy of the detection. The objective of this work is to study and highlight the best techniques that help removing voids and thus improving the accuracy of the SVDD. Experimental results show that choosing the appropriate techniques and parameters can significantly improve the accuracy of the SVDD

An evaluation of candidate oxidation resistant materials

Ground based testing of materials considered for Kapton solar array blanket protection, graphite epoxy structural member protection, and high temperature radiators was performed in an RF plasma asher. Ashing rates for Kapton were correlated with rates measured on STS-8 to determine the exposure time equivalent to one year in low Earth orbit (LEO) at a constant density space station orbital flux. Protective coatings on Kapton from Tekmat, Andus Corporation, and LeRC were evaluated in the plasma asher and mass loss rates per unit area were measured for each sample. All samples evaluated provided some protection to the underlying surface but ion beam sputter deposited samples of SiO2 and SiO2 with 8% polytetrafluoroethylene (PTFE) showed no evidence of degradation after 47 hours of exposure. Mica paint was evaluated as a protective coating for graphite epoxy structural members. Mica appears to be resistant to attack by atomic oxygen but only offers some limited protection as a paint because the paint vehicles evaluated to date were not resistant to atomic oxygen. Four materials were selected for evaluation as candidate radiator materials: stainless steel, copper, niobium-1% zirconium, and titanium-6% aluminum-4% vanadium. These materials were surface textured by various means to improve their emittance. Emittances as high as 0.93 at 2.5 microns for stainless steel and 0.89 at 2.5 microns for Nb-1 Zr were obtained from surface texturing. There were no significant changes in emittance after asher exposure

Power flow variation based on extreme learning machine algorithm in power system

The main focus of this paper is a study that empowers us to understand how the temperature variation affects the transmission line resistance and as a result the power flow analysis with a specific end goal to assess losses in the electrical network. The paper is composed of two sections; the first part is a power flow study under normal conditions utilizing the neural network approach while the second investigated extreme learning machine algorithm efficiency and exactitude. Extreme learning machine algorithm has been used to settle several complications in power system: load forecasting, fault diagnosis, economic dispatch, security, transient stability; Thus, we proposed to study this technique to figure out this sort of complex issue.The study was conducted for IEEE 30 bus test system. The simulation results are exposed and analyzed in detail at the end of this paper

Conception et diffusion de ressources en ligne pour gérer la diversité cognitive des élèves et favoriser leur réussite dans l'apprentissage de l'algèbre

54 pages (annexes en plus)Les projets Pépite, LINGOT et PépiMEP résultent d'une longue collaboration entre chercheurs en didactique des mathématiques, chercheurs en informatique, enseignants et formateurs. Ces projets visent d'une part à concevoir des outils à destination des enseignants pour gérer l'hétérogénéité des apprentissages des élèves en algèbre élémentaire en fin de scolarité obligatoire et, d'autre part, à en évaluer les usages réels en classe et leur influence sur l'activité des élèves en algèbre. Le projet PépiMEP a permis la diffusion, sur la plateforme en ligne LaboMEP de l'association Sésamath, accessible gratuitement à grande échelle, des résultats issus des premières recherches sur le diagnostic et l'enseignement adapté aux besoins repérés des élèves

The Transient Stability Study of a Synchronous Generator Based on the Rotor Angle Stability

Transient stability is an important aspect in the operation of electrical power system. In case of fault occurs in the system, the determining of fault clearing time of circuit breaker is considered one of the main factors to ensure power transfer of the system. This paper is aim to study the transient stability of single machine infinite bus system (SMIB), based on the rotor angle stability. The study is performed to determine the influence of the critical clearing time of the circuit breakers on the rotor angle stability of the generator in the case of three phase fault. For obtaining and determining numerically the nature of the rotor angle of machine, we applied the Step-by-step method for different values of fault clearing time. The results of simulation indicate that determine of critical clearing time is a major evaluation in stability studies. The system model is created in MATLAB/ SIMULINK software

Modelling and performance testing of a digital over-current relay enhanced designed model

Introduction. The over-current relay is widely used to protect distribution and transmission electrical systems against excessive currents occurring due to short circuit or overload conditions. Many works have been carried out in the field of models simulation design of digital over-current relays in the literature, but unfortunately many of them are more complex design models, have very slow execution time and only work in simple faults cases. Purpose. The purpose of this work is to present the performance of a modified and improved model of a digital over-current relay designed in Simulink/MATLAB environment with more simplified design, faster execution time, and able to operate under more complex fault conditions. Methodology. Before starting tests, modelling of over-current relay is presented in details, of which the basic logics of the proposed model to implement inverse and instantaneous characteristics are well explained. Afterwards, various tests are carried out for the performance analysis of the enhanced designed relay model in terms of: operating speed for eliminating faults that has arisen, ability to distinguish between a fault current and load starting current, capacity distinguish between real and temporary fault currents, the way to manage variable faults over time, and the degree of harmony between primary protection relay and back-up protection relay. Originality. The originality of our proposed work consists in the development and improvement of a digital over-current relay model designed in Simulink/MATLAB environment in such way that it becomes able to operate under new harsh test conditions. This developed designed model is implemented and applied in a 400V radial distribution power system with a load that causes a starting current. Results. The obtained values of simulation are compared with the theoretically calculated values and known existing models. The obtained results after various tests validate the good performance of our enhanced designed model.Вступ. Реле надструму широко використовується для захисту електричних систем розподілу та передачі від надмірних струмів, що виникають внаслідок короткого замикання або перевантаження. У літературі було виконано багато робіт у галузі моделювання цифрового реле надструму, але, на жаль, багато з них є більш складними моделями конструкції, з дуже повільним часом виконання, і вони працюють лише у випадках простих несправностей. Метою даної роботи є представлення продуктивності модифікованої та вдосконаленої моделі цифрового реле надструму, розробленої в середовищі Simulink/MATLAB, з більш спрощеною конструкцією, швидшим часом виконання та здатністю працювати в більш складних умовах несправностей. Методологія. Перед початком випробувань детально представлено моделювання реле надструму, з якої добре пояснено основні логіки запропонованої моделі для реалізації зворотних і миттєвих характеристик. Після цього проводяться різноманітні випробування для аналізу продуктивності вдосконаленої розробленої моделі реле з точки зору: швидкості роботи для усунення виниклих несправностей, здатності розрізняти струм несправності та пусковий струм навантаження, можливості розрізняти реальні та тимчасові струми несправності, спосіб управління змінними несправностями в часі та ступінь відповідності реле первинного захисту та реле резервного захисту. Оригінальність запропонованої нами роботи полягає в розробці та вдосконаленні моделі цифрового реле надструму, розробленої в середовищі Simulink/MATLAB таким чином, щоб вона стала здатною працювати в нових жорстких умовах випробувань. Ця розроблена модель реалізована та застосована у радіальної розподільчої енергосистемі 400 В з навантаженням, що викликає пусковий струм. Результати. Отримані результати моделювання порівнюються з теоретично розрахованими значеннями. Результати, отримані після різноманітних випробувань, підтверджують хорошу продуктивність нашої покращеної розробленої моделі

Ameaning-oriented approach to islamic idioms in the western algerian transnational community

La lengua es uno de los principales componentes del transnacionalismo que está ganando cada vez más terreno en la investigación. El uso de la lengua conduce a la creación y/o preservación de conexiones entre espacios distantes, frecuentemente a través de las fronteras nacionales (Jiménez et al, 2009). Un modismo es una frase de uso habitual en la lengua que lleva consigo una herencia cultural e histórica y desempeña un papel fundamental en el uso de esta. Sin embargo, su significado es un reto y se sabe poco sobre él en contextos transnacionales. Este trabajo se interesa por el transnacionalismo idiomático en los países que proclaman el islam como su religión. Se ha optado por Argelia occidental como caso de estudio transnacional en el que los modismos islámicos constituyen una parte importante de las variedades árabes y reflejan diversos aspectos culturales e históricos de la vida cotidiana de los argelinos. En las actividades transnacionales participan no sólo los especialistas en idiomas, sino también las personas que se trasladan a Argelia, como los inmigrantes, los inversores empresariales extranjeros y los estudiantes europeos de Erasmus, además de los emigrantes que abandonan el país: la comprensión idiomática ayuda a los profesores de la lengua extranjera en el país de acogida a instruir mejor a sus hijos. Por lo tanto, este trabajo sugiere la aplicación de este modelo orientado al conocimiento de la lengua extranjera (Purpura, 2016), a los modismos islámicos como una forma de contribuir a la comprensión del transnacionalismo argelino. También intenta comprobar hasta qué punto esta aplicación del modelo podría ser efectiva en la actualidad. Para ello, se han recogido datos de campo y se ha entrevistado a ochenta y ocho informantes. Los resultados muestran que la mayoría de los recursos del modelo pueden aplicarse a los modismos recogidos. Sin embargo, no todos los transnacionales necesitaron pasar posteriormente por todos los estratos del modelo para llegar a la comprensión y producción idiomáticas en el contexto actual. Se aportan además otras sugerencias que podrían mejorar el dominio de los idiomatismos islámicos por parte de los recién llegados a Argelia occidental.Language is one of the main constituents of transnationalism that is increasingly gaining groundin research. Language use leads to the creation and/or preservation of connections between distant spaces, frequently across national boundaries (Jiménezetal,2009). An idiom is a regularly used phrasein the language to carry its cultural and historical heritage and play a vital role in language use. However, at times its meaning might present a challenge while Little is known about it in transnational contexts.This paper deals with idiomatic transnationalism in countries proclaiming Islam as their religion. Choice fell on western Algeria as a transnational study case where Islamic idioms make an important part of Arabic varieties and reflect diverse cultural and historical aspects of the Algerians’ every day life. Not only language specialists are involved in transnational activities, but also individuals moving to Algeria, including immigrants, foreign business investors, European Erasmus students,inaddition to emigrants leaving the country: Idiomatic understanding helps school foreign language teachers in the host country to better instruct their children.There fore, this paper suggests the application of meaning-oriented model of foreign language knowledge (Purpura, 2016) to Islamic idioms as away to contribute to the comprehension of Algerian transnationalism. It also attempts to check the extent to which this model applicability could be currently effective. Observation was under taken to collect data and eighty eightin formants were interviewed. Results showed that most of the model resources could be applied to the idiom collected. Yet, not all transnational individuals needed to go subsequently through all the model layers to reach idiomatic under standing and production in the present context. Further suggestions that might improve the new comers’ proficiency of Islamic idioms in western Algeria were provided

Contribution of DGs in the stability and voltage drop reduction for future MV network in desert regions

Day by day, the integration of decentralized generation in medium voltage networks becomes more important during the last years and even in the near future. This increase causes, at the same time, several negative effects and rarely positive impacts on the stability of the network. Therefore, this work aims at analyzing the impact of ambient temperature on radial distribution network parameters’ e.g.: voltage drop and stability voltage level (index). Based on MATLAB program, different analyses of distributed generation (DG) insertion influence’s on voltage drop in the radial distribution feeder, as well as the influence of climatic conditions such as ambient temperature on network parameters. The Integration of Photovoltaic DGs in MV networks can play an important role in reducing the global warming effect (in voltage drop, and voltage stability index) especially in radial distribution feeder. Furthermore, it protects network’s parameters if its location and power are well selected