1,188 research outputs found

    Appraising shariah committee operations in microfinance firms: PLS approach

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    Increased attention towards the role of the Shariah committee makes demands on processes in the boardroom.In Malaysia, even Islamic microfinance firms are experiencing the challenges of creating well functioning Shariah boards. This paper examines the importance of structures and processes in the Sharia committee boardroom of selected microfinance firms in Malaysia through survey perception of 63 participants.The objective is to determine the engagement and processes affecting the operations of Shariah committee in governing and promoting Islamic microfinance.The contribution of the paper explores the relationship between appraisal processes in the board and board performance.It also examines board policy structures that exist to maximize the Shariah board's monitoring performance.The analysis in the paper found that the current governance mechanisms as nurtured in the roles of Shariah committees for microfinance providers is modestly rated well as potentially effective. However, the Shariah committee is perceived by relevant stakeholders as lacking in combining Islamic knowledge with strategic demands facing IMF.There is also the need to evaluate information sources, and exercise power towards ensuring management accepts and implements its Shariah decisions.Hence, appraisal, policy change, monitoring of board processes and Shariah values are required in the governance mechanism

    Onduleur quasi-Z-source pour un système de traction de véhicules électriques à sources multiples : contrôle et gestion

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    Abstract: Power electronics play a fundamental role and help to achieve the new goals of the automobiles in terms of energy economy and environment. The power electronic converters are the key elements which interface their power sources to the drivetrain of the electric vehicle (EV). They contribute to obtaining high efficiency and performance in power systems. However, traditional inverters such as voltage-source, current-source inverters and conventional two-stage inverters present some conceptual limitations. Consequently, many research efforts have been focused on developing new power electronic converters suitable for EVs application. In order to develop and enhance the performance of commercial multiple sources EV, this dissertation aims to select and to control the impedance source inverter and to provide management approaches for multiple sources EV traction system. A concise review of the main existing topologies of impedance source inverters has been presented. That enables to select QZSI (quasi-Z-source inverter) topology as promising architectures with better performance and reliability. The comparative study between the bidirectional conventional two-stage inverter and QZSI for EV applications has been presented. Furthermore, comparative study between different powertrain topologies regarding batteries aging index factors for an off-road EV has been explored. These studies permit to prove that QZSI topology represents a good candidate to be used in multi-source EV system. For improving the performance of QZSI applied to EVs, optimized fractional order PI (FOPI) controllers for QZSI is designed with the ant colony optimization algorithm (ACO-NM) to obtain more suitable aging performance index values for the battery. Moreover, this thesis proposes a hybrid energy storage system (HESS) for EVs to allow an efficient energy use of the battery for a longer distance coverage. Optimized FOPI controller and the finite control set model predictive controller (FCS-MPC) for HESS using bidirectional QZSI is applied for the multi-source EV. The flux-weakening controller has been designed to provide a correct operation with the maximum available torque at any speed within current and voltage limits. Simulation investigations are performed to verify the topologies studied and the efficacity of the proposed controller structure with the bidirectional QZSI. Furthermore, Opal-RT-based real-time simulation has been implemented to validate the effectiveness of the proposed HESS control strategy. The results confirm the EV performance enhancement with the addition of supercapacitors using the proposed control configuration, allowing the efficient use of battery energy with the reduction of root-mean-square value, the mean value, and the standard deviation by 57%, 59%, and 27%, respectively, of battery current compared to the battery-only based inverter.L'électronique de puissance joue un rôle fondamental et contribue à atteindre les nouveaux objectifs de l'automobile en termes d'économie d'énergie et d'environnement. Les convertisseurs d’électroniques de puissance sont considérés comme les éléments clés qui interfacent leurs sources d'alimentation avec la chaîne de traction du véhicule électrique (VE). Ils contribuent à obtenir une efficacité et des performances élevées dans les systèmes électriques. Cependant, les onduleurs traditionnels tels que les onduleurs à source de tension, les onduleurs à source de courant et les onduleurs conventionnels à deux étages qui constituent les onduleurs les plus couramment utilisés, présentent certaines limitations conceptuelles. Par conséquent, de nombreux efforts de recherche se sont concentrés sur le développement de nouveaux convertisseurs d’électroniques de puissance adaptés à l'application aux véhicules électriques. Afin de développer et d'améliorer les performances des VEs à sources multiples commerciales, cette thèse vise à sélectionner, contrôler l'onduleur à source impédante et fournit une approche de gestion pour l'application du système de traction du VE à sources multiples. Une revue concise des principales topologies existantes d'onduleur à source impédante a été présentée. Cela a permis de sélectionner la topologie de l’onduleur quasi-Z-source (QZS) comme architectures prometteuses pouvant être utilisées dans les véhicules électriques, avec de meilleures performances et de fiabilité. L'étude comparative entre l'onduleur bidirectionnel conventionnel à deux étages et de celui à QZS pour les applications du VE a été présentée. En outre, une étude comparative entre différentes topologies de groupes motopropulseurs concernant les facteurs d'indice de vieillissement des batteries pour une application du VE hors route a été explorée. Ces études ont permis de prouver que la topologie de l’onduleur QZS représente une bonne topologie candidate à utiliser dans un système de VE à sources multiples. Pour améliorer les performances de l’onduleur QZS appliquées aux véhicules électriques, des contrôleurs PI d'ordre fractionnaire (PIOF) optimisés pour l’onduleur QZS sont conçus avec l'algorithme de colonies de fourmis afin d'obtenir des valeurs d'indice de performance de vieillissement plus appropriées pour la batterie. De plus, cette thèse propose un système de stockage d'énergie hybride (SSEH) pour le VE afin de permettre une utilisation efficace de l'énergie de la batterie pour une couverture de distance plus longue et une extension de son autonomie. L’optimisation du contrôleur PIOF et du contrôleur par modèle prédictif d'ensemble de contrôle fini (CMP-ECF) pour l’onduleur QZS bidirectionnel a été appliqué au VE à sources multiples avec des approches de gestion appuyées par des règles. Le contrôleur d'affaiblissement de flux magnétique du moteur a été conçu pour fournir un fonctionnement correct avec le couple maximal disponible à n'importe quelle vitesse dans les limites de courant et de tension. Des investigations et des simulations sont effectuées pour vérifier les différentes topologies étudiées et l'efficacité de la structure de contrôleur proposée avec l’onduleur QZS bidirectionnel. De plus, une simulation en temps réel basée sur Opal-RT a été mise en œuvre pour valider l'efficacité de la stratégie de contrôle SSEH proposée. Les résultats confirment l'amélioration des performances du VE avec l'ajout d'un supercondensateur utilisant la configuration du contrôle proposée, permettant une utilisation efficace de l'énergie de la batterie avec une réduction de la valeur moyenne quadratique, de la valeur moyenne et de l'écart type de 57%, 59% et 27%, respectivement, du courant de la batterie par rapport à l'onduleur connecté directement à la batterie

    Site-Specific Incorporation of Biochemical and Biophysical Probes into Proteins Using Expressed Protein Ligation

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    Protein engineering can be made far more powerful if a protein is not only expressed recombinantly but also altered covalently using synthetic chemistry. These two methods are brought together in the protein semi-synthesis technique Expressed Protein Ligation (EPL). In EPL, recombinant and synthetic polypeptides are joined together via a chemoselective ligation reaction. EPL was originally used to attach synthetic constructs to the C-terminus of recombinant proteins, but is now used to attach recombinant or synthetic polypeptides either at the N- or C-terminus of a protein or into the core of a protein. This thesis illustrates, with three distinct applications, the development of EPL from its original definition to its current understanding. In the first application, a general strategy was developed for the site-specific incorporation of fluorophores into proteins using Abl-SH3 as a model system. In the second application, chemistries were developed that allowed the site-specific introduction of phospho-amino acids into proteins, in this case using the transforming growth factor β receptor I as the model system. In the final application, EPL was used to synthesize several modified versions of the E. coli sigma factor σ70, demonstrating that this method can be used to probe extremely large macromolecules. These studies revealed that EPL works under a variety of reaction conditions and provided paradigms for using this technique to site-specifically insert fluorophores and phosphate groups into proteins. The chemical manipulation of proteins by EPL will be an important tool as researchers strive to characterize the proteomes of organisms

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    Approximate Degree, Secret Sharing, and Concentration Phenomena

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    The epsilon-approximate degree deg~_epsilon(f) of a Boolean function f is the least degree of a real-valued polynomial that approximates f pointwise to within epsilon. A sound and complete certificate for approximate degree being at least k is a pair of probability distributions, also known as a dual polynomial, that are perfectly k-wise indistinguishable, but are distinguishable by f with advantage 1 - epsilon. Our contributions are: - We give a simple, explicit new construction of a dual polynomial for the AND function on n bits, certifying that its epsilon-approximate degree is Omega (sqrt{n log 1/epsilon}). This construction is the first to extend to the notion of weighted degree, and yields the first explicit certificate that the 1/3-approximate degree of any (possibly unbalanced) read-once DNF is Omega(sqrt{n}). It draws a novel connection between the approximate degree of AND and anti-concentration of the Binomial distribution. - We show that any pair of symmetric distributions on n-bit strings that are perfectly k-wise indistinguishable are also statistically K-wise indistinguishable with at most K^{3/2} * exp (-Omega (k^2/K)) error for all k < K <= n/64. This bound is essentially tight, and implies that any symmetric function f is a reconstruction function with constant advantage for a ramp secret sharing scheme that is secure against size-K coalitions with statistical error K^{3/2} * exp (-Omega (deg~_{1/3}(f)^2/K)) for all values of K up to n/64 simultaneously. Previous secret sharing schemes required that K be determined in advance, and only worked for f=AND. Our analysis draws another new connection between approximate degree and concentration phenomena. As a corollary of this result, we show that for any d deg~_{1/3}(f). These upper and lower bounds were also previously only known in the case f=AND

    Effects of Cost on the Quality of MBA Programmes in Ugandan Universities

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    The current study set out to assess the effect of cost on the quality of Master of Business Administration [MBA] programmes in Ugandan Universities using a hypothesised model. The research was carried out in six universities of Makerere, the Islamic University in Uganda, Nkumba, Ndejje, Makerere Business School and Uganda Martyrs University.A purposely designed questionnaire was distributed to 100 students in the six universities. The findings showed that: one, there were significant differences [F (5, 44) = 3.606,

    War and the debt burden in the Great Lakes region

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    Paper for a conference organised by The Department of Political Science Makerere University, held in Entebbe 10-12 July 2000.The task of this paper is to advance the view that the Highly Indebted Poor Countries (HIPCs) of Great Lakes Region would do better to endeavor and resolve political disharmony using peacemaking strategies rather than engaging in wars which are horribly expensive and largely counter-productive. Many African nations, as the case of the Great Lakes region illustrates, have a propensity to resort to war first and foremost and only remembering negotiated peace afterwards
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