Optimal Number, Location, and Size of Distributed Generators in Distribution Systems by Symbiotic Organism Search Based Method

This paper proposes an approach based on the Symbiotic Organism Search (SOS) for optimal determining sizing, siting, and number of Distributed Generations (DG) in distribution systems. The objective of the problem is to minimize the power loss of the system subject to the equality and inequality constraints such as power balance, bus voltage limits, DG capacity limits, and DG penetration limit. The SOS approach is defined as the symbiotic relationship observed between two organisms in an ecosystem, which does not need the control parameters like other meta-heuristic algorithms in the literature. For the implementation of the proposed method to the problem, an integrated approach of Loss Sensitivity Factor (LSF) is used to determine the optimal location for installation of DG units, and SOS is used to find the optimal size of DG units. The proposed method has been tested on IEEE 33-bus, 69-bus, and 118-bus radial distribution systems. The obtained results from the SOS algorithm have been compared to those of other methods in the literature. The simulated results have demonstrated that the proposed SOS method has a very good performance and effectiveness for the problem of optimal placement of DG units in distribution systems

Refinement of an inverse analysis procedure for estimating tensile constitutive law of UHPC

As regard to cementitious composite materials added a certain dosage of fiber, estimation of tensile constitutive law through inverse analysis methods is no longer extraordinary. However, development or improvement to achieve an effective method for estimating such a tensile behavior of fiber reinforced concrete (FRC) or Ultra high-performance concrete (UHPC) is still an interesting topic to researchers. In this respect, the paper presents a development of inverse analysis method developed by Lopez to obtain the stress-strain behavior of UHPC from the four-point bending test. By applying optimization algorithm into the iterative procedure of method, an improvement could be obtained for the inverse analysis with a high degree of automation in calculation. A post-process treatment for inverse analysis results is also proposed to bring a finer agreement between the tensile behavior curve obtained by the inverse analysis and result curve of uniaxial tensile test (UTT). The effectivity of process is shown through a comparison between the result obtained by the proposed method and the result in Lopez’s public paper

Refinement of an inverse analysis procedure for estimating tensile constitutive law of UHPC

As regard to cementitious composite materials added a certain dosage of fiber, estimation of tensile constitutive law through inverse analysis methods is no longer extraordinary. However, development or improvement to achieve an effective method for estimating such a tensile behavior of fiber reinforced concrete (FRC) or Ultra high-performance concrete (UHPC) is still an interesting topic to researchers. In this respect, the paper presents a development of inverse analysis method developed by Lopez to obtain the stress-strain behavior of UHPC from the four-point bending test. By applying optimization algorithm into the iterative procedure of method, an improvement could be obtained for the inverse analysis with a high degree of automation in calculation. A post-process treatment for inverse analysis results is also proposed to bring a finer agreement between the tensile behavior curve obtained by the inverse analysis and result curve of uniaxial tensile test (UTT). The effectivity of process is shown through a comparison between the result obtained by the proposed method and the result in Lopez’s public paper

Model Updating for Large-Scale Railway Bridge Using Grey Wolf Algorithm and Genetic Alghorithms

This paper proposes a novel hybrid algorithm to deal with an inverse problem of a large-scale truss bridge. Grey Wolf Optimization (GWO) Algorithm is a well-known and widely applied metaheuristic algorithm. Nevertheless, GWO has two major drawbacks. First, this algorithm depends crucially on the positions of the leading Wolf. If the position of the leaderis far from the best solution, the obtained results are poor. On the other hand, GWO does not own capacities to improve the quality of new generations if elements are trapped into local minima. To remedy the shortcomings of GWO, we propose a hybrid algorithm combining GWO with Genetic Algorithm (GA), termed HGWO-GA. This proposed method contains two key features (1) based on crossover and mutation capacities, GA is first utilized to generate the high-quality elements (2) after that, the optimization capacity of GWO is employed to seek the optimal solutions. To assess the effectiveness of the proposed approach, a large-scale truss bridge is employed for model updating. The obtained results show that HGWO-GA not only provides a good agreement between numerical and experimental results but also outperforms traditional GWO in terms of accuracy

Noise propagation in power converter : modeling and attenuation approaches

In this thesis, an analysis of noise propagation and complete design guidelines for low noise low power circuit of a power converter is presented. In literature, majority of publication deal with noise propagation in the high power circuit resulting in high EMI, which may not pass EMI standards. Unfortunately, EMI standards are not relevant to solve EMI issues in the board level. Consequently, this thesis focuses on noise propagation in the low power circuit, consisting of sensing and control circuits. Noise in the low power circuit can create noisy feedback signals, leading to bad performance and poor reliability converter. In order to resolve this issue, this thesis helps the designers to understand well noise in low power circuit in term of its existence, source and propagation paths. Based on this knowledge, noise mitigation techniques are developed to ensure the performance and reliability of the power converter. The proposed methods can be applied in the early design stage or improving noise profile of a complete converter. This thesis begins with the experimental observations of noise in the low power circuit of a typical Buck converter in several operating points of the high power circuit and different components of low power circuit. Based on the experimental results, the noise propagation paths are analyzed without considering differential (DM) and common modes (CM) separately. To further understand the effects of converter design on noise profile, the fundamental parts of the low power circuit including Gate driver, passive devices and low power rails supplying all functional circuits, are studied. These researches result in the proposed models of Gate driver at high frequency, the General Impedance Representation (GIR) of passive devices, and the computational model of the low power rails, which will be presented in the contents of this thesis. Furthermore, the noise mitigation techniques are developed to reduce noise in the low power circuit based on knowledge of these aforementioned parts. Noise is attenuated locally at the Gate driver by using Y-capacitor. In addition, the GIR and 2D model of low power rails provide powerful tools for optimal design. In each part of this thesis, the literature review, proposed models/approaches, computational and experimental results will be presented to validate the effectiveness of the thesis contributions

Analyse des graphes de reactions biochimiques avec une application au réseau metabolique de la cellule de plante

Nowadays, systems biology are facing the challenges of analysing the huge amount of biological data and large-scale metabolic networks. Although several methods have been developed in recent years to solve this problem, it is existing hardness in studying these data and interpreting the obtained results comprehensively. This thesis focuses on analysis of structural properties, computation of elementary flux modes and determination of minimal cut sets of the heterotrophic plant cellmetabolic network. In our research, we have collaborated with biologists to reconstructa mid-size metabolic network of this heterotrophic plant cell. This network contains about 90 nodes and 150 edges. First step, we have done the analysis of structural properties by using graph theory measures, with the aim of finding its owned organisation. The central points orhub reactions found in this step do not explain clearly the network structure. The small-world or scale-free attributes have been investigated, but they do not give more useful information. In the second step, one of the promising analysis methods, named elementary flux modes, givesa large number of solutions, around hundreds of thousands of feasible metabolic pathways that is difficult to handle them manually. In the third step, minimal cut sets computation, a dual approach of elementary flux modes, has been used to enumerate all minimal and unique sets of reactions stopping the feasible pathways found in the previous step. The number of minimal cut sets has a decreasing trend in large-scale networks in the case of growing the network size. We have also combined elementary flux modes analysis and minimal cut sets computation to find the relationship among the two sets of results. The findings reveal the importance of minimal cut sets in use of seeking the hierarchical structure of this network through elementary flux modes. We have set up the circumstance that what will be happened if glucose entry is absent. Bi analysis of small minimal cut sets we have been able to found set of reactions which has to be present to produce the different sugars or metabolites of interest in absence of glucose entry. Minimal cut sets of size 2 have been used to identify 8 reactions which play the role of the skeleton/core of our network. In addition to these first results, by using minimal cut sets of size 3, we have pointed out five reactions as the starting point of creating a new branch in creationof feasible pathways. These 13 reactions create a hierarchical classification of elementary flux modes set. It helps us understanding more clearly the production of metabolites of interest inside the plant cell metabolism.Aujourd’hui, la biologie des systèmes est confrontée aux défis de l’analyse de l’énorme quantité de données biologiques et à la taille des réseaux métaboliques pour des analyses à grande échelle. Bien que plusieurs méthodes aient été développées au cours des dernières années pour résoudre ce problème, ce sujet reste un domaine de recherche en plein essor. Cette thèse se concentre sur l’analyse des propriétés structurales, le calcul des modes élémentaires de flux et la détermination d’ensembles de coupe minimales du graphe formé par ces réseaux. Dans notre recherche, nous avons collaboré avec des biologistes pour reconstruire un réseau métabolique de taille moyenne du métabolisme cellulaire de la plante, environ 90 noeuds et 150 arêtes. En premier lieu, nous avons fait l’analyse des propriétés structurelles du réseau dans le but de trouver son organisation. Les réactions points centraux de ce réseau trouvés dans cette étape n’expliquent pas clairement la structure du réseau. Les mesures classiques de propriétés des graphes ne donnent pas plus d’informations utiles. En deuxième lieu, nous avons calculé les modes élémentaires de flux qui permettent de trouver les chemins uniques et minimaux dans un réseau métabolique, cette méthode donne un grand nombre de solutions, autour des centaines de milliers de voies métaboliques possibles qu’il est difficile de gérer manuellement. Enfin, les coupes minimales de graphe, ont été utilisés pour énumérer tous les ensembles minimaux et uniques des réactions qui stoppent les voies possibles trouvées à la précédente étape. Le nombre de coupes minimales a une tendance à ne pas croître exponentiellement avec la taille du réseau a contrario des modes élémentaires de flux. Nous avons combiné l’analyse de ces modes et les ensembles de coupe pour améliorer l’analyse du réseau. Les résultats montrent l’importance d’ensembles de coupe pour la recherche de la structure hiérarchique du réseau à travers modes de flux élémentaires. Nous avons étudié un cas particulier : qu’arrive-t-il si on stoppe l’entrée de glucose ? En utilisant les coupes minimales de taille deux, huit réactions ont toujours été trouvés dans les modes élémentaires qui permettent la production des différents sucres et métabolites d’intérêt au cas où le glucose est arrêté. Ces huit réactions jouent le rôle du squelette / coeur de notre réseau. En élargissant notre analyse aux coupes minimales de taille 3, nous avons identifié cinq réactions comme point de branchement entre différent modes. Ces 13 réactions créent une classification hiérarchique des modes de flux élémentaires fixés et nous ont permis de réduire considérablement le nombre de cas à étudier (approximativement divisé par 10) dans l’analyse des chemins réalisables dans le réseau métabolique. La combinaison de ces deux outils nous a permis d’approcher plus efficacement l’étude de la production des différents métabolites d’intérêt par la cellule de plante hétérotrophique

Shape grammar based adaptive building envelopes: Towards a novel climate responsive facade systems for sustainable architectural design in Vietnam.

The concept of a dynamic building enclosure is a relatively novel and unexplored area in sustainable architectural design and engineering and as such, could be considered a new paradigm. These façade systems, kinetic and adaptive in their nature, can provide opportunities for significant reductions in building energy use and CO2 emissions, whilst at the same time having a positive impact on the quality of the indoor environment. Current research in this area reports on a growing increase in the application of new generative design approaches and computational techniques to assist the design of adaptable kinetic systems and to help quantify their relationships between the building envelope and the environment. In this research, a novel application of shape grammar for the design of kinetic façade shading systems has been developed, based upon a generative design approach that controls the creation of complex shape composites, starting from a set of initial shapes and pre-defined rules of their composition. Shape grammars provide an interesting generative design archetype in which a set of shape rules can be recursively applied to create a language of designs, with the rules themselves becoming descriptors of such generated designs. The research is inspired by traditional patterns and ornaments in Vietnam, seen as an important symbol of its cultural heritage, especially in the era of globalisation where many developing countries, including Vietnam, are experiencing substantial modernist transformations in their cities. Those are often perceived as a cause of the loss of both visual and historical connections with indigenous architectural origins and traditions. This research hence investigates how these aspects of spatial culture could be interpreted and used in designing of novel façade shading systems that draw their inspiration from Vietnamese vernacular styles and cultural identity. At the same time, they also have to satisfy modern building performance demands, such as a reduction in energy consumption and enhanced indoor comfort. This led to the exploration of a creative form-finding for different building façade shading configurations, the performance of which was tested via simulation and evaluation of indoor daylight levels and corresponding heating and cooling loads. The developed façade structures are intended to adapt real-time, via responding to both results of an undertaken simulation and data-regulation protocols responsible for sensing and processing building performance data. To this extent, a strategy for BIM integrated sustainable design analysis (SDA) has also been deliberated, as a framework for exploring the integration of building management systems (BMS) into smart building environments (SBEs). Finally, the research reports on the findings of a prototype system development and its testing, allowing continuous evaluation of multiple solutions and presenting an opportunity for further improvement via multi-objective optimisation, which would be very difficult to do, if not impossible, with conventional design methods.N/

Dynamic response analysis of truss bridges under the effect of moving vehicles

With the characteristics of heavy and concentrated loads, the influence of moving loads on the dynamic response of the bridges is significant. Therefore, in this paper, the dynamic response of a large-scale truss bridge is studied to consider the effect of the various parameters of moving loads. The considered main parameters consist of moving mass, moving velocity, and type of moving loads. The nonlinear dynamics of the bridge based on time history analysis are obtained using the Wilson-  method. four time history – based dynamic analysis method including modal superposition in frequency domain, modal superposition in time domain; direct time integration, and direct solution in the frequency domain are employed to analysis the obtained results. To compare the effectiveness of the aforementioned method. A large-scale railway truss bridge is employed for dynamic response analysis. The obtained results give more insight into the nature of the problem and help to determine the significant parameters of moving load affecting the bridge response

Ranking load in microgrid based on fuzzy analytic hierarchy process and technique for order of preference by similarity to ideal solution algorithm for load shedding problem

This paper proposes a method to rank the loads in the microgrid by means of a weight that combines the criteria together in terms of both technical and economic aspects. The fuzzy analytic hierarchy process technique for order of preference by similarity to ideal solution (fuzzy AHP TOPSIS) algorithm is used to calculate this combined weight. The criteria to be considered are load importance factor (LIF), voltage electrical distance (VED) and voltage sensitivity index (VSI). The fuzzy algorithm helps to fuzzy the judgment matrix of the analytic hierarchy process (AHP) method, making it easier to compare objects with each other and remove the uncertainty of the AHP method. The technique for order of preference by similarity to ideal solution (TOPSIS) algorithm is used to normalize the decision matrix, determine the positive and negative ideal solutions to calculate the index of proximity to the ideal solution, and finally rank all the alternatives. The combination of fuzzy AHP and TOPSIS algorithms is the optimal combination for decision making and ranking problems in a multi-criteria environment. The 19-bus microgrid system is applied to calculate and demonstrate the effectiveness of the proposed method