Efficient method for transformer models implementation in distribution load flow matrix

Introduction. Most distribution networks are unbalanced and therefore require a specific solution for load flow. There are many works on the subject in the literature, but they mainly focus on simple network configurations. Among the methods dedicated to this problem, one can refer to the load flow method based on the bus injection to branch current and branch current to bus voltage matrices. Problem. Although this method is regarded as simple and complete, its drawback is the difficulty in supporting the transformer model as well as its winding connection types. Nevertheless, the method requires the system per unit to derive the load flow solution. Goal. In the present paper, our concern is the implementation of distribution transformers in the modeling and calculation of load flow in unbalanced networks. Methodology. Unlike previous method, distribution transformer model is introduced in the topology matrices without simplifying assumptions. Particularly, topology matrices were modified to take into account all winding types of both primary and secondary sides of transformer that conserve the equivalent scheme of an ideal transformer in series with an impedance. In addition, the adopted transformer models overcome the singularity problem that can be encountered when switching from the primary to the secondary side of transformer and inversely. Practical value. The proposed approach was applied to various distribution networks such as IEEE 4-nodes, IEEE 13-nodes and IEEE 37-nodes. The obtained results validate the method and show its effectiveness.Вступ. Більшість розподільчих мереж незбалансовані і тому потребують спеціального рішення для потоку навантаження. У літературі є багато робіт на цю тему, але переважно вони присвячені простим мережевим конфігураціям. Серед методів, присвячених цій проблемі, можна назвати метод потоку навантаження, заснований на введенні шини в матрицю струму відгалуження і відгалуження струму в матрицю напруги шини. Проблема. Хоча цей метод вважається простим та повним, його недоліком є складність підтримки моделі трансформатора, а також типів з’єднання його обмоток. Проте метод вимагає системи на одиницю для отримання рішення про потік навантаження. Мета. У цій статті нас цікавить застосування розподільних трансформаторів для моделювання та розрахунку потоку навантаження у незбалансованих мережах. Методологія. На відміну від попереднього методу, модель розподільного трансформатора вводиться в матриці топології без спрощення припущень. Зокрема, матриці топології були змінені, щоб врахувати всі типи обмоток як первинної, так і вторинної сторін трансформатора, які зберігають еквівалентну схему послідовно ідеально включеного трансформатора з імпедансом. Крім того, прийняті моделі трансформаторів долають проблему сингулярності, з якою можна зіткнутися при перемиканні з первинної на вторинну обмотку трансформатора і навпаки. Практична цінність. Пропонований підхід був застосований до різних розподільних мереж, таких як IEEE з 4 вузлами, IEEE з 13 вузлами та IEEE з 37 вузлами. Отримані результати підтверджують метод та показують його ефективність

Effects of plant hormones and 20-hydroxyecdysone on tomato (Lycopersicum esculentum) seed germination and seedlings growth

20-hydroxyecdysone (20E) is the major phytoecdysteroid of about 6% of plants. Its role in plant physiology has not been fully elucidated. In this work we studied the effects of 20E application on somemorphological and biochemical parameters of tomato, Lycopersicum esculentum, seed during germination and seedling development (5 d). We compared the 20E effects with the action of phytohormones: gibberellic acid (GA3), naftalen acetic acid (NAA), benzyl amino purine (BAP). NAA treatment resulted in marked reduction in shoot length. GA3 treatment promoted maximal shoot elongation. BAP affected negatively shoot length only at late stages, while 20E application stimulated shoot elongation at early stages and reduced it on the fifth day; NAA inhibited root elongation all along the test period. GA3 treatment had no effect on root length, whereas BAP showed strong inhibition on root elongation. On the other hand, 20E showed a weak inhibition of root elongation on the fifth day. As compared to control and to other treatments, NAA and 20E provoked a drastic decrease in protein contents during seedling growth, whereas a high increase was observed under BAP treatment. Electrophoresis revealed that protein bands were not degraded and mobilized after NAA treatmentwhile in control or after 20E and others phytohormones applications, protein patters displayed weak band intensities and some of them were not detected. NAA, GA3 and BAP provoked a decrease inproline content during seedlings, while the effect of 20E on proline levels varied during germination and plantlet development. This work showed that 20E like phytohormones fulfil some bioactive actionsduring germination and seedlings growth in tomato

The use of soft shore protection measures in shallow lakes: Research methodology and case study

AbstractShore protection in lakes is an issue of major importance in Switzerland where several big lakes in plains suffer from a pronounced bank erosion. For the moment, in shallow lakes, soft and biotechnical protection measures proved their reliability. Unfortunately, the scientific basis for the design of such techniques does not exist in some cases or not appropriate enough in order to have an optimized effect. Therefore, the aim of an on-going research project is to study, on the basis of physical and numerical modeling, the impact of such measures on the shores regarding bank erosion, and to establish the main basis for their dimensioning. A 2-D numerical model was used to simulate the eroded beach of Préverenges on the North coast of Lake Geneva. Hence, this case study allowed a better understanding of the numerical capacities of the program by modelling wave effect on bedload sediment transport and shore erosion as well as wind role in the generation of littoral currents

End-of-fabrication CMOS process monitor

A set of test 'modules' for verifying the quality of a complementary metal oxide semiconductor (CMOS) process at the end of the wafer fabrication is documented. By electrical testing of specific structures, over thirty parameters are collected characterizing interconnects, dielectrics, contacts, transistors, and inverters. Each test module contains a specification of its purpose, the layout of the test structure, the test procedures, the data reduction algorithms, and exemplary results obtained from 3-, 2-, or 1.6-micrometer CMOS/bulk processes. The document is intended to establish standard process qualification procedures for Application Specific Integrated Circuits (ASIC's)

Anévrysme de l’aorte ascendante associé à une insuffisance aortique massive: complication rare et grave de la maladie de Behçet

L'atteinte artérielle au cours de la maladie de Behçet survient chez 2 à 12% des patients et se traduit par des lésions oblitérantes et/ou anévrysmales prédominant sur les gros troncs. Les complications cardiaques sont plus rares (1 à 6%) touchant les trois tuniques. En revanche, les anévrysmes de l'aorte ascendante associés à une insuffisance aortique restent une complication très rare de la maladie de Behçet. Nous rapportons l'observation d'un jeune patient de 35ans suivie pour une maladie de Behçet compliquée d'un anévrysme de l'aorte ascendante associé à une régurgitation aortique massive. Le diagnostic a été posé sur les données cliniques radiologiques de l'échocardiographie et de la tomodensitométrie puis confirmé à l'examen histologique de la pièce. Le traitement était chirurgical et a consisté en un remplacement total de la racine de l'aorte à coeur ouvert selon la technique de Bentall afin d'éviter le risque de rupture ou de dissection. L'évolution à 18 mois de l'intervention était favorable. Le traitement médical associant la corticothérapie et les immunosuppresseurs est la règle en postopératoire pour éviter les récidives

Product assurance technology for custom LSI/VLSI electronics

The technology for obtaining custom integrated circuits from CMOS-bulk silicon foundries using a universal set of layout rules is presented. The technical efforts were guided by the requirement to develop a 3 micron CMOS test chip for the Combined Release and Radiation Effects Satellite (CRRES). This chip contains both analog and digital circuits. The development employed all the elements required to obtain custom circuits from silicon foundries, including circuit design, foundry interfacing, circuit test, and circuit qualification

Product assurance technology for procuring reliable, radiation-hard, custom LSI/VLSI electronics

Advanced measurement methods using microelectronic test chips are described. These chips are intended to be used in acquiring the data needed to qualify Application Specific Integrated Circuits (ASIC's) for space use. Efforts were focused on developing the technology for obtaining custom IC's from CMOS/bulk silicon foundries. A series of test chips were developed: a parametric test strip, a fault chip, a set of reliability chips, and the CRRES (Combined Release and Radiation Effects Satellite) chip, a test circuit for monitoring space radiation effects. The technical accomplishments of the effort include: (1) development of a fault chip that contains a set of test structures used to evaluate the density of various process-induced defects; (2) development of new test structures and testing techniques for measuring gate-oxide capacitance, gate-overlap capacitance, and propagation delay; (3) development of a set of reliability chips that are used to evaluate failure mechanisms in CMOS/bulk: interconnect and contact electromigration and time-dependent dielectric breakdown; (4) development of MOSFET parameter extraction procedures for evaluating subthreshold characteristics; (5) evaluation of test chips and test strips on the second CRRES wafer run; (6) two dedicated fabrication runs for the CRRES chip flight parts; and (7) publication of two papers: one on the split-cross bridge resistor and another on asymmetrical SRAM (static random access memory) cells for single-event upset analysis