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Analysis of Nigeria-Sao Tome and Principe Joint Development and Suggestions for China
Issue:
Volume 4, Issue 3, June 2015
Pages:
123-128
Received:
17 March 2015
Accepted:
29 March 2015
Published:
30 April 2015
Abstract: The Nigeria-Sao Tome and Principe Joint Development is a typical case in Africa. The two states are located in Gulf of Guinea, where delimitation disputes inside are serious and oil competitions among western developed countries outside are fierce, the Nigeria-Sao Tome and Principe Joint Development is carried out on this background. About the implement, several factors play a positive role: stable bilateral relations, adjustments of domestic policies and the establishment of Gulf of Guinea Commission; but oil steal and outside intervention are negative factors. About the content, many special provisions, such as Proportion, Management, Petroleum Development Contracts and Disputes Settlement are contained in joint development agreement. However, there are still some problems unsolved: unequal status of the two states, lack of information sharing mechanism and supervision mechanism, multinational corporations’ monopoly. China should learn from it, deepen mutual understanding and mutual trust with countries nearby to promote joint development in South China Sea.
Abstract: The Nigeria-Sao Tome and Principe Joint Development is a typical case in Africa. The two states are located in Gulf of Guinea, where delimitation disputes inside are serious and oil competitions among western developed countries outside are fierce, the Nigeria-Sao Tome and Principe Joint Development is carried out on this background. About the impl...
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Simulation and Modelling of a Turbocharged Compression Ignition Engine
Brahim Menacer,
Mostefa Bouchetara
Issue:
Volume 4, Issue 3, June 2015
Pages:
129-145
Received:
13 February 2015
Accepted:
1 March 2015
Published:
12 May 2015
Abstract: The increase in fuel price is constraining car manufacturers to produce highly efficient engines with more regulations in terms of pollutant emissions. The increasing complexity of modern engines has rendered the prototyping phase long and expensive. This is where engine modeling becomes in the recent years extremely useful and can be used as an indispensable tool when developing new engine concepts. This study deals with the numerical simulation and performance prediction of a turbocharged diesel engine with direct injection. To predict the engine performances, we developed a computer program for simulating the operation of a turbocharged diesel engine, and used the commercial GT-Power software to validate the simulation results. In this work we carried out a comparative study of indicated mean effective pressure, mean effective pressure, power, torque and brake specific fuel consumption obtained by the analytical model for thermodynamic cycle simulation of a turbocharged diesel engine with the computer program developed in the language FORTRAN and those with the GT-Power software. The language FORTRAN program developed is currently used in the course of modeling and simulation of engine performance.
Abstract: The increase in fuel price is constraining car manufacturers to produce highly efficient engines with more regulations in terms of pollutant emissions. The increasing complexity of modern engines has rendered the prototyping phase long and expensive. This is where engine modeling becomes in the recent years extremely useful and can be used as an in...
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PMSG Based Wind Energy Conversion with Space Vector Modulation
M. Magesh Kumar,
R. Sundareswaran
Issue:
Volume 4, Issue 3, June 2015
Pages:
146-152
Received:
22 April 2015
Accepted:
1 May 2015
Published:
12 May 2015
Abstract: Space Vector Modulation (SVM) based Direct Torque Control (DTC) scheme is used for a variable –speed direct drive Permanent Magnet Synchronous Generator (PMSG) in a wind power generation system. SVM Provides more flexibility for inverter voltage utilization, in order to compensate the torque and flux errors in a smoother way than conventional DTC. SVM based DTC maintains constant switching frequency and it can be applied using closed loop torque control, for minimization of torque ripple. Over the conventional Doubly Fed Induction Generator (DFIG), PMSG has several advantages. The PMSG based on Wind Energy Conversion System (WECS) can be connected to the turbine without gearbox. The gearbox causes in the cost of maintenance, and then it will decrease the weight of the nacelle. Additionally, the generators have a better efficiency and have been slightly cheaper. This provides maximum flexibility, enabling full real and reactive power control. The SVM-DTC regulated PMSG wind turbine can achieve fast torque response, relatively low torque ripples, and extracts the maximum power. The effectiveness of the SVM-DTC control scheme for PMSG has been demonstrated by MATLAB simulation.
Abstract: Space Vector Modulation (SVM) based Direct Torque Control (DTC) scheme is used for a variable –speed direct drive Permanent Magnet Synchronous Generator (PMSG) in a wind power generation system. SVM Provides more flexibility for inverter voltage utilization, in order to compensate the torque and flux errors in a smoother way than conventional DTC. ...
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Multi Objective Dynamic Economic Dispatch with Cubic Cost Functions
Moses Peter Musau,
Nicodemus Odero Abungu,
Cyrus Wabuge Wekesa
Issue:
Volume 4, Issue 3, June 2015
Pages:
153-167
Received:
16 April 2015
Accepted:
29 April 2015
Published:
15 May 2015
Abstract: The formulation and solution of the Dynamic Economic Dispatch (DED) problem is one of the key disciplines in modern power system operation, planning, operation and control. Past researches have considered DED on Quadratic Cost Functions (QCF), with only few works considering higher order cost functions which are more accurate. The Static Economic Dispatch (SED) has been widely tackled in past researches, however, it is the DED problem that represents a real life power system. There is need to review this problem and establish a more practical formulation of the same taking into consideration all the objectives and constraints possible. The methods used in the solution of DED problem have evolved from the traditional deterministic ones, to the pure heuristic, and finally to the state of the heart hybrids. The hybrids methods have been developed to exalt the strengths and improve the weaknesses of the base method. Such optimisation methods need to be reviewed and classified. This paper will do an in depth review of the DED problem on both quadratic and cubic cost functions. Further it will provide a detailed classification of the methods used to solve the problem as its complexity increases. Consequently, three method Hybrids is the way go as far as the solution of the cubic Multi Objective DED (MODED) with five objectives is concerned.
Abstract: The formulation and solution of the Dynamic Economic Dispatch (DED) problem is one of the key disciplines in modern power system operation, planning, operation and control. Past researches have considered DED on Quadratic Cost Functions (QCF), with only few works considering higher order cost functions which are more accurate. The Static Economic D...
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Performance Characteristics of Automotive Air Conditioning System with Refrigerant R134a and Its Alternatives
Issue:
Volume 4, Issue 3, June 2015
Pages:
168-177
Received:
22 May 2015
Accepted:
6 June 2015
Published:
19 June 2015
Abstract: In this paper, the thermal performance characteristics of automotive air conditioning are carried out. Experimental analysis of R134a automotive air conditioning system with variable speed compressor is investigated. The purpose is to present a clear view on the effect of compressor speed, and condensing temperature on the thermal characteristics of automotive air conditioning. This study is exteneded theoritcally to cover more alternatives of the current R134a due to its impact of the Global Warming Potential GWP. The possibility of using low-GWP refrigerants of R152a, R1234yf, and R1234ze as alternatives to R134a in automotive air conditioning has been assessed. The refrigerants are investigated over a wide range of condensing temperature, evaporating temperature and refrigerant mass flow rate. The assessment is accomplished with cooling capacity, compressor power, coefficient of performance, pressure ratio, and condenser load. The results indicated that, the refrigerant R1234yf is much more environmentally accepted and has the best thermal performance among all investigated refrigerants.
Abstract: In this paper, the thermal performance characteristics of automotive air conditioning are carried out. Experimental analysis of R134a automotive air conditioning system with variable speed compressor is investigated. The purpose is to present a clear view on the effect of compressor speed, and condensing temperature on the thermal characteristics o...
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Study on the Experiments and the Numerical Analysis of Exchange Flow Behavior in the Unstably Stratified Field
Motoo Fumizawa,
Yoshiharu Saito,
Naoya Uchiyama,
Takahiro Nakayama
Issue:
Volume 4, Issue 3, June 2015
Pages:
178-183
Received:
27 May 2015
Accepted:
7 June 2015
Published:
19 June 2015
Abstract: In the flow mechanism of unstably stratified field, occurs after Rayleigh-Taylor instability. Buoyancy-driven exchange flows were investigated the helium-air flow in the vertical narrow pathway between upper air chamber and lower helium chamber. Exchange flows may occur following the opening of a window for ventilation, when fire breaks out in a room, as well as when a pipe ruptures in a high temperature gas-cooled nuclear reactor. The numerical analysis and experiment in this paper was carried out in a test chamber filled with helium and the flow was visualized using the smoke wire method. The flow behavior was recorded by a high-speed camera combined with a computer system. The image of the flow was transferred to digital data, and the flow velocity was measured by PTV and PIV software. The mass fraction in the test chamber was measured using electronic balance. The detected data was arranged by the densimetric Froude number of the exchange flow rate derived from the dimensional analysis. A method of mass increment was developed and applied to measure the exchange flow rate. As the result, it is revealed that three dimensional structure of counter current exchange flow in the narrow flow path such as rotation and circulation flows by the optical system, mass inclement method and numerical analysis of moving particle method as well as HSMAC method.
Abstract: In the flow mechanism of unstably stratified field, occurs after Rayleigh-Taylor instability. Buoyancy-driven exchange flows were investigated the helium-air flow in the vertical narrow pathway between upper air chamber and lower helium chamber. Exchange flows may occur following the opening of a window for ventilation, when fire breaks out in a ro...
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Energy Efficiency and Cost Effectiveness of Solar Water Heaters
Issue:
Volume 4, Issue 3, June 2015
Pages:
184-188
Received:
29 May 2015
Accepted:
10 June 2015
Published:
25 June 2015
Abstract: There are different opinions on the question of energy and economic efficiency of solar water heaters. Some researchers believe in high effectiveness of solar water heater application while others questions their cost effectiveness. In this arti¬cle detailed investigations have been accomplished to discover energy and economic real efficien¬cy of different types of solar water heaters on the base of suggested procedure for their real payback periods determination. It’s proved that flat type solar water heater has much longer payback than newly suggested cylindrical shell and tube type solar water heater.
Abstract: There are different opinions on the question of energy and economic efficiency of solar water heaters. Some researchers believe in high effectiveness of solar water heater application while others questions their cost effectiveness. In this arti¬cle detailed investigations have been accomplished to discover energy and economic real efficien¬cy of d...
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