Comparison of Power Flow Algorithms for inclusion in On-line Power Systems Operation Tools

The goal of this thesis is to develop a new, fast, adaptive load flow algorithm that automatically alternates numerical methods including Newton-Raphson method, Gauss-Seidel method and Gauss method for a load flow run to achieve less run time. Unlike the proposed method, the traditional load flow analysis uses only one numerical method at a time. This adaptive algorithm performs all the computation for finding the bus voltage angles and magnitudes, real and reactive powers for the given generation and load values, while keeping track of the proximity to convergence of a solution. This work focuses on finding the algorithm that uses multiple numerical techniques, rather than investigating programming techniques and programming languages. The convergence time is compared with those from using each of the numerical techniques. The proposed method is implemented on the IEEE 39-bus system with different contingencies and the solutions obtained are verified with PowerWorld Simulator, a commercial software for load flow analysis

A Computational Paradigm on Network-Based Models of Computation

The maturation of computer science has strengthened the need to consolidate isolated algorithms and techniques into general computational paradigms. The main goal of this dissertation is to provide a unifying framework which captures the essence of a number of problems in seemingly unrelated contexts in database design, pattern recognition, image processing, VLSI design, computer vision, and robot navigation. The main contribution of this work is to provide a computational paradigm which involves the unifying framework, referred to as the multiple Query problem, along with a generic solution to the Multiple Query problem. To demonstrate the applicability of the paradigm, a number of problems from different areas of computer science are solved by formulating them in this framework. Also, to show practical relevance, two fundamental problems were implemented in the C language using MPI. The code can be ported onto many commercially available parallel computers; in particular, the code was tested on an IBM-SP2 and on a network of workstations

Editorial

No Abstract

Topical Skills for Accounting Graduates within Changing Business Environment: Stakeholders’ Satisfaction Levels in Rwanda

Institution managers have always been seeking competent accountants and accounting technicians to fill the gaps created by the requirements of changing business environment and criticize the existing skills of newly graduated and less experienced accounting job aspirants from Rwandan  Institutions of Higher Learning. This paper analyses the satisfaction levels of various stakeholders in Rwanda towards the skills held by accounting-employees and employers’ expectations, as this could remedy to the competence gap between the job market demand and human resource availability in accounting field. The target population includes the managers of selected institutions in Rwanda, the accountants employed by these institutions and the heads of departments in higher learning institutions delivering accounting programs. The sample was chosen randomly from each stratum of population from the selected districts. The study discovers that the competences acquired are not appropriate to fulfil the necessary skills required in accounting job. Collaboration between accounting firms and academic institutions is needed to synergize accounting practical training with theoretical learning in the classroom. Accountants will also have to equip with other extra knowledge and soft skills (information technology, critical thinking and effective communication) to match the market needs. Key Words: Business environment, competences, topical skills, accountants, accounting technicians, employers’ requirements

Acute esotropia in the setting of heroin withdrawal

Acute onset of concomitant esotropia presenting with diplopia can be seen in the setting of heroin withdrawal. We report a case of acute esotropia in a young white male during heroin withdrawal. A sudden onset of eye deviation is usually considered an ominous sign and patients are subjected to a multitude of diagnostic tests and investigations. Acute esotropia in the setting of heroin withdrawal is typically self-limiting. This case presentation can increase the awareness among physicians for a timely diagnosis, and prevent unnecessary diagnostic testing and further consultations.Includes bibliographical reference

The effect of chemical additives on cutting forces and rate of wear of natural diamonds

Call number: LD2668 .T4 1978 R37Master of Scienc

Effect of dielectric constant of medium on chemical speciation of L-histidine complexes of Co(II), Ni(II) and Cu(II)

Chemical speciation of binary complexes of Co(II), Ni(II) and Cu(II) ions with L-histidine have been studied pH metrically in the concentration range of 0–60% v/v DMSO-water mixtures maintaining an ionic strength of 0.16 M at 303 K. Alkalimetric titrations were carried out in different relative concentrations of metal and histidine. Stability constants of various models of binary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The species detected are MLH, ML­2, ML2H, ML2H2 and ML2H4 for Co(II); ML­2, ML2H, ML2H2 and ML2H4 for Ni(II); and MLH, ML2, ML2H and ML2H2 for Cu(II). The chemical speciation, metal bioavailability and transportation are explained based on the distribution diagrams. KEY WORDS: L-Histidine, Chemical speciation, Essential metals, Binary complexes, Bioavailability, DMSO Bull. Chem. Soc. Ethiop. 2012, 26(2), 227-238.DOI: http://dx.doi.org/10.4314/bcse.v26i2.

Time-Optimal Tree Computations on Sparse Meshes

The main goal of this work is to fathom the suitability of the mesh with multiple broadcasting architecture (MMB) for some tree-related computations. We view our contribution at two levels: on the one hand, we exhibit time lower bounds for a number of tree-related problems on the MMB. On the other hand, we show that these lower bounds are tight by exhibiting time-optimal tree algorithms on the MMB. Specifically, we show that the task of encoding and/or decoding n-node binary and ordered trees cannot be solved faster than Ω(log n) time even if the MMB has an infinite number of processors. We then go on to show that this lower bound is tight. We also show that the task of reconstructing n-node binary trees and ordered trees from their traversais can be performed in O(1) time on the same architecture. Our algorithms rely on novel time-optimal algorithms on sequences of parentheses that we also develop

Polarization of Electrospun PVDF Fiber Mats and Fiber Yarns

Electrospun fibers are of interest in a number of applications due to their small size, simplicity of fabrication, and ease of modification of properties. Piezoelectric polymers such as Polyvinylidene Fluoride (PVDF) can be charged when formed in the electrospinning process. This chapter discusses fabrication of PVDF fiber mats and fiber yarns and the measurement of their charge using a custom-made Faraday bucket. The results show the measured charge per mass of fiber mats was greater than the values measured for the yarns of the same mass. The measured charges may be related to both mass and external surface areas of the mats and yarn samples. It was observed the area/mass ratios of the fiber yarns were more than 30% less than the fiber mats