The Exploitation Of A Nonrenewable Resource Under Imperfect Competition

In this thesis, we investigate some problems concerning the exploitation of a nonrenewable resource under imperfect competition. The approach adopted here is that of partial equilibrium. The thesis consists of five chapters, with each chapter dealing with a specific topic.;In Chapter One, we study the pattern of resource extraction exected of a dominant firm facing competition from a naive competitive fringe. In Chapter Two, we build a model of monopoly resource extraction under stochastic entry with consumers as potential entrants. In Chapter Three, we build a model of simultaneous resource extraction and exploration under monopoly. Our model of exploration is spatially oriented and deals directly with location uncertainty. In Chapter Four, we present a game-theoretical model to study the phenomenon of information spillover encountered in the exploration for a nonrenewable resource. Chapter Five deals with a differential game of resource extraction under oligopoly. Here, we present a rigorous proof of the existence of a Cournot-Nash equilibrium. When the market demand curve satisfies a suitable assumption, we show that this equilibrium is unique and provide an algorithm to find it

Radial basis function neural network control for parallel spatial robot

The derivation of motion equations of constrained spatial multibody system is an important problem of dynamics and control of parallel robots. The paper firstly presents an overview of the calculating the torque of the driving stages of the parallel robots using Kronecker product. The main content of this paper is to derive the inverse dynamics controllers based on the radial basis function (RBF) neural network control law for parallel robot manipulators. Finally,  numerical simulation of the inverse dynamics controller for a 3-RRR delta robot manipulator is presented as an illustrative example

DYNAMIC MODEL WITH A NEW FORMULATION OF CORIOLIS/CENTRIFUGAL MATRIX FOR ROBOT MANIPULATORS

The paper presents a complete generalized procedure based on the Euler-Lagrange equations to build the matrix form of dynamic equations, called dynamic model, for robot manipulators. In addition, a new formulation of the Coriolis/centrifugal matrix is proposed. The link linear and angular velocities are formulated explicitly. Therefore, the translational and rotational Jacobian matrices can be derived straightforward from definition, which makes the calculation of the generalized inertia matrix more convenient. By using Kronecker product, a new Coriolis/centrifugal matrix formulation is set up directly in matrix-based manner and guarantees the skew symmetry property of robot dynamic equations. This important property is usually exploited for developing many control methodologies. The validation of the proposal formulation is confirmed through the symbolic solution and simulation of a typical robot manipulator

A novel method for determining fixed running time in operating electric train tracking optimal speed profile

Tracking the optimal speed profile in electric train operation has been proposed as a potential solution for reducing energy consumption in electric train operation, at no cost to improve infrastructure of existing Metro lines as well. However, the optimal speed profile needs to meet fixed running time. Therefore, this paper focuses on a new method for determining the fixed running time complied with the scheduled timetable when trains track the optimal speed profile. The novel method to ensure the fixed running time is the numerical-analytical one. Calculating accelerating time ta, coasting time tc, braking time tb via values of holding speed vh, braking speed vb of optimal speed profile with the constraint condition: the running time equal to the demand time. The other hands, vh and vb are determined by solving nonlinear equations with constraint conditions. Additionally, changing running time suit for each operation stage of metro lines or lines starting to conduct schedules by the numerical-analytical method is quite easy. Simulation results obtained for two scenarios with data collected from electrified trains of Cat Linh-Ha Dong metro line, Vietnam show that running time complied with scheduled timetables, energy saving by tracking optimal speed profile for the entire route is up to 8.7%, if the running time is one second longer than original time, energy saving is about 11.96%

Study on some groups of microorganism during the forest rehabilitation process in Song Ma district, Son La province

The paper has made assessement on changes of some soil microorganism groups during the process of forest rehabilitation after shifting cultivation and after clear cutting in Song Ma district, Son La province. Sampling has been made in forest areas naturally regenerated for 4-6; 9-11; 14-16 and above 20 years after shifting cultivation and after clear cutting. The results have shown that the total aerobic bacteria, the total actinomycetes and the total microfungi have increased from the rehabilitation stage of 4-6 years (3.12×102; 1.23×103 and 8.05×102 CFU/g respectively in forest areas after shifting cultivation and 4.25×104; 2.32×103 and 7.32×103CFU/g respectively in forest areas after clear cutting) to the rehabilitation stage of ≥ 20 years (3.54×105; 2.23×104 and 2.51×104 CFU/g respectively in forest areas after shifting cultivation and 4.35×106; 2.72×105 and 5.46×105 CFU/g respectively in forest areas after clear cutting). The capacity in free nitrogen fixation, in cellulose decomposition, in phosphates decomposition, and in polysaccharide production of the aerobic bacteria, of actinomycetes, and of microfungi is lowest during the first forest rehabilitation stage (4-6 years), then it grows and reaches the highest value during the stage of≥20 years (5.60×103; 2.75×104; 2.10×103; 1.36×104 CFU/g respectively in forest areas after shifting cultivation and 5.24×103; 3.14×105; 4.27×104; 5.39×104 CFU/g respectively in forest areas after clear cutting)

Speed profile optimization of an electrified train in Cat Linh-Ha Dong metro line based on pontryagin's maximum principle

An urban railway is a complex technical system that consumes large amounts of energy, but this means of transportation still has been obtained more and more popularity in densely populated cities because of its features of high-capacity transportation capability, high speed, security, punctuality, lower emission, reduction of traffic congestion. The improved energy consumption and environment are two of the main objectives for future transportation. Electrified trains can meet these objectives by the recuperation and reuse of regenerative braking energy and by the energy - efficient operation. Two methods are to enhance energy efficiency: one is to improve technology (e.g., using energy storage system, reversible or active substations to recuperate regenerative braking energy, replacing traction electric motors  by energy-efficient traction system as permanent magnet electrical motors; train's mass reduction by lightweight material mass...); the other is to improve operational procedures (e.g. energy efficient driving including: eco-driving; speed profile optimization; Driving Advice System (DAS); Automatic Train Operation (ATO); traffic management optimization...). Among a lot of above solutions for saving energy, which one is suitable for current conditions of metro lines in Vietnam. The paper proposes the optimization method based on Pontryagin's Maximum Principle (PMP) to find the optimal speed profile for electrified train of Cat Linh-Ha Dong metro line, Vietnam in an effort to minimize the train operation energy consumption

MULTI-PIXEL PHOTON COUNTER FOR OPERATING A TABLETOP COSMIC RAY DETECTOR UNDER LOOSELY CONTROLLED CONDITIONS

The multi-pixel photon counter (MPPC) has recently emerged as a great type of silicon photomultiplier to replace or compensate for conventional vacuum-based photomultiplier tubes. An MPPC provides many advantageous features, such as high electrical gain, outstanding photon detection efficiency, fast timing response, immunity to magnetic fields, low-voltage operation, compactness, portability, and cost-effectiveness. This article examines the electrical and optical characteristics of an MPPC under loosely controlled environmental conditions. We also report a measurement of the light yield captured by the MPPC when a cosmic ray passes through the plastic scintillator, demonstrating that such a setup is suitable as a simple, cost-effective tabletop cosmic ray detector for educational and research purposes

Social capital and job search success: The case of undergraduates in Ho Chi Minh City, Vietnam

The literature has proven the positive role of social capital on job search success, but the researchers' community has not been convinced completely because social capital is not always good. Moreover, only certain dimensions of the two latent variables were analyzed in the previous research though they are multidimensional. This paper approached the social capital and job search success multidimensionally by applying Partial Least Square - Structural Equation Model (PLS-SEM) to explore the path that social capital impacts on job search success. The primary data of 400 undergraduates in Ho Chi Minh City, Vietnam were used in the model. The results have confirmed the positive role of bonding social capital and general trust in acquired job quality, job search cost and job search convenience