Economic dispatch with prohibited operating zones using fast computation evolutionary programming algorithm

This paper presents an efficient and simple approach for solving the economic dispatch (ED) problem with units having prohibited operating zones. The operating region of the units having prohibited zones is broken into isolated feasible sub-regions which results in multiple decision spaces for the economic dispatch problem. The optimal solution will lie in one of the feasible decision spaces and can be found using the conventional λ–δ iterative method in each of the feasible decision spaces. But, this elaborate search procedure is time consuming and not acceptable for on-line application. In this paper, a simple and novel approach is proposed. In this approach, the optimal solution and the corresponding optimum system lambda are determined using an efficient fast computation evolutionary programming algorithm (FCEPA) without considering the prohibited operating zones. Then, a small set of advantageous decision spaces is formed by combining the feasible sub-regions of the fuel cost curve intervening the prohibited zones in the neighbourhood of the optimal system lambda. A penalty cost for each advantageous decision space is judiciously computed using participation factor. The most advantageous decision space is found out by comparing the penalty cost of the decision spaces. The optimal solution in the most advantageous decision space is obtained using the FCEPA. The proposed algorithm is tested on a number of sample systems with units possessing prohibited zones. The study results reveal that the proposed approach is computationally efficient and would be a competent method for solving economic dispatch problem with units having prohibited operating zones.     

Hydrogel capsules for sustained drug release

Interpenetrating polymer networks (IPNs) based on polyacrylamide and polyvinyl alcohol for hydrogel capsules were synthesized. These polymer networks were evaluated as drug-delivery devices using Crystal Violet and Bromothymol Blue as model drugs. The observed drug release is higher for semi-II-IPN than full-IPN. The drug-release behaviors from these capsules were analyzed by the exponent relation Mt/Mα = Ktⁿ, where “K” and “n” are constants and Mt/Mα is the fraction of the drug released until time “t.” The constant “n” was found to be above 0.5, which suggests that the release of drug from the capsules follows the non-Fickian diffusional model. The mechanical behavior of hydrogel disks were also analyzed. © 1994 John Wiley & Sons, Inc.     

Effect of tuned unified power flow controller to mitigate the rotor speed instability of fixed-speed wind turbines

In this paper, the dynamic performance of grid connected Wind Energy Conversion System (WECS) is analysed in terms of the newly defined concept of rotor speed stability. The WECS is considered as a fixed-speed system that is equipped with a squirrel-cage induction generator. The drive-train is represented as a two-mass model. Results show that for a particular fault simulated the voltage at the Point of Common Coupling (PCC) drops below 80% immediately after fault application and settles at a low value. The rotor speed of induction generators becomes unstable. In order to improve the low voltage ride-through of WECS under fault conditions and to damp the rotor speed oscillations of induction generator, an Unified Power Flow Controller (UPFC) is employed. The gains of this FACTS controller are tuned with a simple Genetic Algorithm (GA). It is observed that UPFC helps not only in regulating the voltage, but also in mitigating the rotor speed instability.     

AB crosslinked polymers based on cationomeric polyurethane and poly(methyl methacrylate): Static and dynamic mechanical studies

Vinyl‐terminated polyurethane (VTPU) was prepared by end‐functionalizing isocyanate‐terminated prepolymers with 2‐bromoethanol and subsequently quartenizing with 4‐vinylpyridine. The vinyl functionality was then effectively utilized for preparing AB crosslinked polymers (ABCPs) with methyl methacrylate (MMA). ABCPs prepared with variable weight ratios on PTMG₁₀₀₀‐based VTPU/MMA (8/2, 6/4, 5/5, 4/6, 2/8) and those prepared at a 5/5 weight ratio with different polyols (PTMG₁₀₀₀, PPG₁₀₀₀, and PCL₁₂₅₀) in VTPU were characterized by Fourier transform infrared spectroscopy (FTIR) and further analyzed for thermal and mechanical properties. FTIR spectral results confirm quartenization of heterocyclic nitrogen, leading to crosslinking. Thermogravimetric analyses show enhanced thermal stability of the crosslinked systems. The stress–strain measurements reveal increasing tensile strength with increasing amounts of MMA. Comparison of dynamic mechanical spectra of ABCPs based on PTMG₁₀₀₀ shows that the 5/5 composition exhibits good damping over a broad temperature range. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 813–821, 2001     

基于iSCSI的IP存储广域网可用性分析

随着远程容灾、内容分发、数据网格等不断发展,要求数据存储的范围从局域网拓展到广域网.本文提出了基于iSCSI协议的IP存储广域网系统模型,并利用一种新的可用性度量标准-任务完成概率,分析了IP存储广域网的可用性.分析结果表明：当任务数量达到百万时,系统完成概率在99.7%左右.     

Polyurethane telechelic cationomers containing end functional 4-vinylpyridinium moieties

Summary Telechelic polyurethane cationomers containing end functional 4-vinylpyridinium moieties have been synthesized by the reaction of 4-vinylpyridine on 2-bromoethanol terminated polyurethane. The polyurethanes were characterized by FTIR, FTNMR and DSC studies. The introduction of ionic groups into the polyurethane shifts the T_g to lower temperatures, the shift in T_g further increases with increase in ionic groups.     

Kinetics of propellant decomposition

Equations for solid-state decompositions which are controlled by the phase-boundary movement and nucleation have been examined using ammonium perchlorate/polystyrene propellant decomposition at 503 K and 533 K. It was found that 3 different equations governed by the nucleation process show a good fit of data at these temperatures. However, the best fit was obtained for the following Avrami-Erofeev equation, [-In (1 - α]^1/4=kt.