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This paper proposes a new load balancing strategy based on a systematical research on current load balancing mechanism. The new strategy combines the methods of gossip propagation and replication policy, and adopts two different propagation policies to cope with light and heavy overloaded conditions so as to improve performance of networks. At the end of this paper, we prove the reliability and scalability...
A content delivery network (CDN) is expected to provide high performance content delivery, which requires scalable infrastructure to achieve global coverage. The provision of such infrastructure may form a substantial entry barrier for new CDN providers, as well as affecting commercial viability of the existing ones. Peering of CDNs can be a way to allow dynamic infrastructural cooperation between...
In this paper a method for TCAD evaluation of RF-Power transistors for high-efficiency operation using drain bias-modulation is presented. The method is based on large signal time-domain transient computational load-pull. With the method, intrinsic device parasitics and mechanisms affecting device efficiency under drain bias modulation can be investigated and optimized for the application making it...
This paper presents an analysis of the impact ionization phenomenon encountered in AlGaAs/GaInAs/GaAs PHEMTs. Two characterizations techniques have been used. At first, pulsed S-parameter measurements in the Impact Ionization (II) region have been required to identify the cut-off frequency of the phenomenon. Then, using these measurements, we propose a new small-signal model taking into account the...
We present and validate an enhanced analytical queueing network model of zoned RAID. The model focuses on RAID levels 01 and 5, and yields the distribution of I/O request response time. Whereas our previous work could only support arrival streams of I/O requests of the same type, the model presented here supports heterogeneous streams with a mixture of read and write requests. This improved realism...
A key obstacle to large-scale network simulation over PC clusters is the memory balancing problem where a memory-overloaded machine can slow down an entire simulation due to disk I/O overhead. Memory balancing is complicated by (i) the dfficulty of estimating the peak memory consumption of a group of nodes during network partitioning-a consequence of per-node peak memory not being synchronized-and...
A new backoff algorithm is proposed to enhance the performance of the IEEE 802.11 distributed coordination function (DCF) which employs binary exponential backoff (BEB) algorithm. The proposed algorithm, called the low time delay-multiplicative increase-multiplicative/slow decrease (LTD-MMSD) backoff algorithm, is quite simple to implement while significantly improving the network performance over...
Obtaining representative and concise I/O workloads for the purpose of projecting the performance of storage systems remains a challenge due to the complex nature of I/O behaviors. Previous studies have shown that disk I/O traffic can be represented as an independent and identically distributed random process in some workloads and a self-similar process in others. Additionally, workloads in the presence...
In this paper, a renewable power generation system is firstly introduced. This system consists of four important subsystems: a diesel generation subsystem, a photovoltaic (PV) subsystem, a DC/AC conversion subsystem and an electric double-layer capacitor (EDLC) energy-storage subsystem. The corresponding control methods of these subsystems are given in this paper. Next, a new prediction model-selftuning-weight...
This paper presented a system of Aircraft Power Distribution System (APDS). Large-signal models of synchronous generator, three phase boost converter and inverter was developed. A two-port network interconnection rule was chose as a special convention about voltage and current variable of component exchange, and a system level model of APDS was performed. The system model was designed to assessment...
It is difficult to detect islanding in distributed generation system for power balance between the output of inverter and the load as well as multi grid-connected inverters. Some of frequency or phase shift methods are ineffective when the phase match between the output of inverter and the load. A new adaptive active frequency drift method (AAFD) for islanding detection is proposed in this paper....
The converting circuit requires high performance such as the output current with high accuracy, low ripple (les0.2 %) and full-range regulated in power accumulator battery testing system for electric vehicles (EV). In this paper, a three-phase current rectifier (CSR) is taken as the main circuit. Double-loop control strategy which is base on the feedback of grid current and the output current is used,...
Transformer models are important in performing load flow procedure, especially in distribution power systems. This paper summarizes the detailed transformer models with various connection types using phase coordinates, such as two-winding transformers, open wye-delta with a mid-tap grounded on the secondary side and other special connection types. But in some conditions, the nodal admittance submatrices...
A novel semi-physical simulation platform for inverter is proposed. The driving circuit and SPWM bridge are replaced by a low power level circuits of operational amplifier and logic ICs, and DSP controller exactly the same with that for the real system. The semi-physical simulation platform can be used for system-level research, especially for control algorithm design, with equivalent inverter systempsilas...
The field of power electronics poses challenging control problems that cannot be treated in a complete manner using traditional modeling and controller design approaches for the reason that power devices are typical hybrid systems in nature. The power devices become more and more complex for the tendency to be interconnected and large scale. It is very important to detect symptom in the early of large...
With renewable energy generating rapid growth, multi-power structure optimization problem with the grid-connected PV power has been a cause of concern. This paper presents Markov decision-making process (MDP) conditions, optimal dynamic programming strategy, N-stage total expectation reward criteria and total expectation cost of MDP model in multi-power structure optimization with grid-connected PV...
Recent the electrical machines for electric home appliances require several design points such as compact size, high torque density, high efficiency and noise reduction and so on. In this paper, inner rotor type of IPMSM (interior permanent magnet synchronous motor) is designed focusing on improving efficiency and power factor and reducing cogging torque and size to improve characteristics for washing...
This paper is concerned with high performance control of three-phase UPS system. The basic requirements of a UPS control system are mentioned. Different control techniques are classified and their performance is briefly described. A hybrid learning-adaptive controller is proposed based on the performance of existing methods. For the learning part, a Repetitive Controller (RC) is used and a Model Reference...
A comprehensive power quality controller combined with Thyristor Controlled Reactors (TCR) and Resonant Impedance Type Hybrid Active Filter (RITHAF) is proposed in this paper for power distribution system. The RITHAF topology presented in the paper is different from the conventional Active Power Filter (APF). The basic of the new RITHAF topology is to add a Fundamental Series Resonance Circuit (FSRC)...
The electromagnetic damp characteristics, namely, the characteristics of electromagnetic torque varying according to angular velocity, of permanent magnet synchronous generator (PMSG) were derived by phasor method. The relationships between the characteristics and PMSG interior parameters were discussed. Transient process and electromechanical time constant were proposed. Both the analysis result...
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