Automated Guided Vehicle (AGV) Container-Job deployment is essentially a vehicle-dispatching problem. In this problem, the impact of vehicle dispatching polices on the ship makespan for discharging and/or loading operations is analyzed. In particular, given a storage location for each container to be discharged from the ship and given the current location of each container to be loaded onto the ship, the problem is to propose an efficient deployment scheme to dispatch vehicles to containers so as to minimize the makespan of the ship so as to increase the throughput. The makespan of the ship refers to the time a ship spends at the port for loading and unloading operations. In this paper, we will compare the performance of current deployment scheme used with the new proposed deployment scheme, both with deadlock prediction & avoidance algorithm done in previous study [1]. The prediction & avoidance algorithm predicts and avoids cyclic deadlock. The current deployment scheme, namely pmds makes use of a greedy heuristics which dispatches the available vehicle that will reach the quay with the minimum amount of time the vehicle has to spend waiting for the crane to discharge/load the container from/onto the ship. The new deployment scheme, namely mcf aims to formulate the problem as a minimum cost flow problem, which will then be solved by network simplex code. The two simulation models are implemented using discrete-event simulation software, AutoMod, and the performances of both deployment schemes are analyzed. The simulation results show that the new deployment scheme will result in a higher throughput and lower ship makespan than the current deployment scheme. / Singapore-MIT Alliance (SMA)

A unique approach is developed for evaluating Human Capital (workforce) requirements. With this approach, new ways of measuring personnel availability are proposed and available to ensure that an organization remains ready to provide timely, relevant, and accurate products and services in support of its strategic objectives over its planning horizon. The development of this analysis and methodology was established as an alternative approach to existing studies for determining appropriate hiring and attrition rates and to maintain appropriate personnel levels of effectiveness to support existing and future missions. The contribution of this research is a prescribed method for the strategic analyst to incorporate a personnel and cost simulation model within the framework of Human Resources Human Capital forecasting which can be used to project personnel requirements and evaluate workforce sustainment, at least cost, through time. This will allow various personnel managers to evaluate multiple resource strategies, present and future, maintaining near “perfect” hiring and attrition policies to support its future Human Capital assets.

As structure and size of electric power distribution systems are getting more complex, distribution automation schemes become more attractive. One of the features that is desirable in an automated system is feeder reconfiguration for loss reduction. Loss reduction can make considerable savings for a utility and results in released system capacity. There is also improved voltage regulation in the system as a result of reduced feeder voltage drop. In this thesis, multi branch exchange algorithm is introduced to solve the network reconfiguration for loss reduction problem. The proposed technique is based on heuristic techniques applied to constraint satisfaction optimization problems. A critical review of earlier methods related with feeder reconfiguration is presented. A computer program was developed using Matlab to simulate this algorithm and results of simulations demonstrate its advantages over single branch exchange method. Moreover, the results show that the final configuration is independent of the initial configuration and give assurance that any solution offered will have a radial configuration with all loads connected.

The optimum values for the section variables like channel side slope,bottom width,depth and radius for triangular,rectangular, trapezoidal and circular channels are computed by minimizing the cost of the channel section.Manning &rsquo / s uniform flow formula is treated as a constraint for the optimization model.The cost function is arranged to include the cost of lining,cost of earthwork and the increment in the cost of earthwork with the depth below the ground surface.The optimum values of section variables are expressed as simple functions of unit cost terms.Unique values of optimum section variables are obtained for the case of minimum area or minimum wetted perimeter problems.

In this thesis, we consider how to reduce the communication cost of the key exchange procedures as many as possible, while the secure group communication can still be achieved. Due to the energy consumption is usually proportional to the distance, we use the shortest paths algorithm to find the shortest communication paths between any pair of the secure group members. We first propose a straightforward heuristic named Minimum-Energy First-Selected ( MEFS ). MEFS tries to select the pair of group members which has less communication cost than all other pairs have at every time. Though MEFS performs better than random selecting, it still has some weakness in solving the energy-aware key management problem. So we use the concept of the minimum cost flow problem, and by appropriate transformation, then we get the optimal solution of the energy-aware key management problem under some constraints. At last, the simulation results proves that the minimum cost flow approach actually works better than MEFS does.

Given two sets of points $A$ and $B$ ($|A| = m$, $|B| = n$), we seek to find a minimum-weight many-to-many matching which seeks to match each point in $A$ to at least one point in $B$ and vice versa. Each matched pair (an edge) has a weight. The goal is to find the matching that minimizes the total weight. We study two kinds of problems depending on the edge weight used. The first edge weight is the Euclidean distance, $d_1$. The second is edge weight is the square of the Euclidean distance, $d_2$. There already exists an $O(k\log k)$ algorithm for $d_1$, where $k=m+n$. We provide an $O(mn)$ algorithm for the $d_2$ problem. We also solve the problem of finding the minimum-weight matching when the sets $A$ and $B$ are allowed to be translated on the real line. We present an $O(mnk \log k)$ algorithm for the $d_1$ problem and an $O(3^{mn})$ algorithm for the $d_2$. Furthermore, we also deal with the special case where $A$ and $B$ lie on a circle of a specific circumference. We present an $O(k^2 \log k)$ algorithm and $O(kmn)$ algorithm for solving the minimum-weight matching for the $d_1$, and $d_2$ weights respectively. Much like the problem on the real line, we extend this problem to allow the sets $A$ and $B$ to be rotated on the circle. We try to find the minimum-weight many-to-many matching when rotations are allowed. For $d_1$ we present an $O(k^2mn \log k)$ algorithm and a $O(3^{mn})$ algorithm for $d_2$. / Thesis (Master, Computing) -- Queen's University, 2010-11-08 20:48:18.968

Single phase switched reluctance machines (SRMs) have a special place in the emerging high-volume, low-cost and low-performance applications in appliances and also in high-speed low-power motor drives in various industrial applications. Single phase SRMs have a number of drawbacks: low power density as they have only 50% utilization of windings, lack of self-starting feature unless otherwise built in to the machine, most of the times with permanent magnets or sometimes with distinct and special machine rotor configurations or additional mechanisms. Many of these approaches are expensive or make the manufacturing process more difficult. In order to overcome such disadvantages a method involving interpoles and windings is discussed in this research. Also, a new and novel converter topology requiring only a single switch and a single diode is realized. This research tests the concepts and feasibility of this new single-phase SRM motor topology and converter in one quadrant operation. The converter electronics and a simple minimum component, minimum cost analog converter are designed and implemented. The entire system is simulated and evaluated on its advantages and disadvantages. Simple testing without load is performed. This system has a large number of possibilities for development. Due to its lightweight, compact design and efficient, variable high-speed operation, the system might find many applications in pumps, fans, and drills. / Master of Science

Esta dissertação trata do problema da k-árvore de custo mínimo (kMST): dados um grafo conexo G, um custo não-negativo c_e para cada aresta e e um número inteiro positivo k, encontrar uma árvore com k vértices que tenha custo mínimo. O kMST é um problema NP-difícil e portanto não se conhece um algoritmo polinomial para resolvê-lo. Nesta dissertação discutimos alguns casos em que é possível resolver o problema em tempo polinomial. Também são estudados algoritmos de aproximação para o kMST. Entre os algoritmos de aproximação estudados, apresentamos a 2-aproximação desenvolvida por Naveen Garg, que atualmente é o algoritmo com melhor fator de aproximação. / This dissertation studies the minimum cost k-tree problem (kMST): given a connected graph G, a nonnegative cost function c_e for each edge e and a positive integer k, find a minimum cost tree with k vertices. The kMST is an NP-hard problem, which implies that it is not known a polynomial algorithm to solve it. In this dissertation we discuss some cases that can be solved in polynomial time. We also study approximation algorithms for the kMST. Among the approximation algorithms we present the 2-approximation developed by Naveen Garg, which is currently the algorithm with the best approximation factor.

[pt] Esta dissertação apresenta um estudo sobre os custos que incidem sobre o transporte rodoviário de cargas e como estes determinam o melhor momento econômico para a substituição dos equipamentos de transporte. O problema é relevante para a organização militar, cujo principal objetivo é a execução da logística para o Exército. A modelagem matemática foi baseada na coleta de dados na organização militar e no Sistema Integrado de Administração Financeira do Governo Federal (SIAFI). O desenvolvimento do modelo que inclui equações matemáticas foi amparado pela bibliografia pesquisada e nos dados coletados no sistema federal SIAFI. Para a avaliação dos dados foram utilizadas planilhas eletrônicas do Microsoft Excel para se calcular apropriadamente os resultados. Os veículos considerados são utilizados em cinco grandes eixos de deslocamento dentro do território nacional. Estes veículos foram divididos em quatro categorias de acordo com o peso bruto total. Quando o modelo apresentou médio ou fraco grau de correlação múltipla (R2), outras funções matemáticas foram buscadas para melhorar o grau de correlação. Os resultados são mostrados de modo analítico e por meio de tabelas e gráficos com valores expressos em unidades monetárias em função do tempo de uso dos veículos. / [en] This dissertation presents a study about all the costs that fall upon the freight transportation in order to determine the best economic moment to replace transportation equipments. The problem is relevant to the military organization, whose main objective is the execution of logistics for the Army. The mathematical modeling was based on data collect in the military organization and in the Federal System Financial Administration (SIAFI). The development of the model wich includes mathematical equations was supported by bibliography research and data collected in the SIAFI federal system. For the evaluation of the data has used electronic spread sheets of Microsoft Excel was used for the calculation and the fitting of the results. The vehicles considered are used in five large axels of displacements along the national territory. These vehicles have been divided in four categories according to its total gross weight. When the model presented a medium or weak degree of multiple correlation (R2), others mathematical functions have been searched in order to improve the correlation degree. Results are shown in an analytical way and through tables and graphs wich express values in monetary terms as a time function of use of the vehicles.

Esta dissertação trata do problema da k-árvore de custo mínimo (kMST): dados um grafo conexo G, um custo não-negativo c_e para cada aresta e e um número inteiro positivo k, encontrar uma árvore com k vértices que tenha custo mínimo. O kMST é um problema NP-difícil e portanto não se conhece um algoritmo polinomial para resolvê-lo. Nesta dissertação discutimos alguns casos em que é possível resolver o problema em tempo polinomial. Também são estudados algoritmos de aproximação para o kMST. Entre os algoritmos de aproximação estudados, apresentamos a 2-aproximação desenvolvida por Naveen Garg, que atualmente é o algoritmo com melhor fator de aproximação. / This dissertation studies the minimum cost k-tree problem (kMST): given a connected graph G, a nonnegative cost function c_e for each edge e and a positive integer k, find a minimum cost tree with k vertices. The kMST is an NP-hard problem, which implies that it is not known a polynomial algorithm to solve it. In this dissertation we discuss some cases that can be solved in polynomial time. We also study approximation algorithms for the kMST. Among the approximation algorithms we present the 2-approximation developed by Naveen Garg, which is currently the algorithm with the best approximation factor.