Construction of an inverse model with cutoff filter and its application to a model feedback control system

An inverse system for a given time‐invariant system has been used as a compensator. However, in control systems which include traditional inverse systems, the adverse effects of sensor noise may seriously influence the systems, because the inverse system generally has high gain in the high‐frequency area. Therefore, in these control systems other compensators than the inverse system must be constructed with complex properties. In this paper, a method of design of a new inverse model with cutoff filter for the Model Feedback Control System (MFCS) is proposed. The inverse model designed by the proposed method is an approximate inverse model for a given model. The approximation can be evaluated by the norm criterion for the difference between the model and the biproper transfer function used for construction of the inverse model. In order to demonstrate the usefulness of the proposed inverse model, this inverse model is applied to the MFCS. By theoretical and numerical analysis it can be shown that the proposed inverse model can reduce sufficiently the effects of sensor noise in the MFCS. © 2000 Scripta Technica, Electr Eng Jpn, 133(4): 79–90, 2000     

基于反扩散火焰的低NOx旋流燃烧器数值模拟

采用非预混稳态小火焰模型（Steady Flamelet Model,SFM）耦合110步甲烷燃烧简化机理和Realizable k-ε模型对反扩散-旋流低氮燃烧器进行模拟,对比分析了不同旋流角度（30°,45°和60°）及过量空气系数（1.05,110,115和1.20）下燃烧时燃烧室内各截面轴向速度分布、中心截面温度及NOx质量浓度分布。详细研究了燃烧室内天然气与空气的燃烧特性及NOx的排放规律。模拟结果表明：随着旋流叶片角度逐渐增大,燃烧室内回流作用逐渐增强,导致火焰长度变短、燃烧室内最高温度及出口NO质量浓度逐渐降低;在旋流叶片角度为60°时,出口NO质量浓度仅为114 mg/m3;随着过量空气系数逐渐增大,火焰末端温度逐渐提高,导致燃烧室出口NO排放量逐渐增大;在过量空气系数为1.2时,出口NO质量浓度达到294 mg/m3,相比于过量空气系数为1.05时,其NO排放量增加153%。     

求解不相关并行机调度问题的十进制多目标灰狼算法

针对不相关并行机调度问题,面向降低能源消耗和减少完工时间的目标,提出一种更高效的基于十进制整数编码的多目标灰狼算法.求解时,采用将资源配置与作业排序相结合的十进制整数编码方式,设计了针对多目标离散调度问题的两阶段位置更新机制.同时引入了N S GA-Ⅱ的精英保留策略,提高了算法的寻优能力,应用最大迭代次数停止准则结束循环并保留最优解.最后,通过数值实验与有代表性的前沿算法进行仿真对比,以验证所提算法的可行性与有效性.     

Predicting the solubility of 1,1-difluoroethane in polystyrene using the perturbed soft chain theory

In this study, the solubility of 1,1-difluoroethane in polystyrene is correlated and predicted using the perturbed soft chain theory (PSCT) and compared with the experimental data in the literature. For correlation, a binary interaction parameter is determined using the experimental solubility data. For prediction, however, the data at infinitely dilute solvent concentration region from inverse gas chromatography (IGC) are used only in determination of the binary interaction parameter. The results were comparable with the experimental data in both cases. © 1998 SCI.     

P（AM-co-AMPS反相微乳胶的制备及其驱油性能评价

以绘制的Span80/Tween80-Kerosene-AM/AMPS/H2O拟三元相图为依据,选择高单体质量分数微乳液体系,在引发剂用量为单体质量0.25%,反应温度为35℃的条件下,通过反相微乳液聚合反应,制得了P（AM-co-AMPS）质量分数为31.0%、相对分子质量为6.8×106的透明、稳定的P（AM-co-AMPS）反相微乳胶,并对其驱油性能进行了考察。结果表明,P（AM-co-AMPS）反相微乳胶与相对分子质量相当的PAM反相微乳胶的驱油性能相比较,P（AM-co-AMPS）反相微乳胶的驱油效率较高。     

Studies of inverse emulsion copolymerization of (2-methacryloyloxyethyl) trimethyl ammonium chloride and acrylamide

Inverse emulsion copolymerization of (2-methacryloyloxyethyl) trimethyl ammonium chloride with acrylamide initiated with potassium persulfate has been studied dilatometrically. Aqueous monomer solutions were emulsified in kerosene with a blend of two surfactants (Span80 and OP10). The gel effect is evident from the increase of the molecular weight with conversion and also from the percentage of conversion versus time curves. Monomer reactivity ratios have been derived as r_AM = 0.38 and r_DMC = 1.69 at pH 6.8. The effects of initiator concentration, concentration, and composition of the monomer, emulsifier concentration, etc., on the polymerization rate and intrinsic viscosity of polymer have been examined. The rate of polymerization (R_p) can be represented by R_p I^0.52[M]^1.50[E]^0.38. The overall activation energy for the rate of polymerization is 66.0 kJ mol (40–65°C). Based on these experimental results, some aspects of the polymerization mechanism are discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1005–1010, 1998     

An inverse analysis of two-phase Stefan problems using imaginary heat sources

This paper presents a new methodology for the inverse analysis of time-dependent two-phase Stefan problems. The problem considered here is that of determining the time dependence of a phase-change interface at several observed temperatures. In our method, imaginary heat sources are arranged in an imaginary domain and then the phase-change interface is identified as the isothermal surface at the melting temperature by controlling the imaginary heat source intensities. Using delta-function imaginary heat sources and their corresponding Green functions, which are pre-calculated numerically, it is shown that the phase-change interface is determined non-iteratively at each time step. We offer numerical examples to demonstrate the capability of the proposed method. © 1998 Scripta Technica, Heat Trans Jpn Res, 27(3): 179–191, 1998     

单台机器总完工时间排序问题的反问题

运筹学和最优化的种种问题(“正问题”)是在已知各有关参数或者数据的条件下,找出最优(最快、成本最省或者效益最大)的方案．所谓的“反问题”,是指已经有一个方案,但在目前的情况下,该方案并非最优,需要考虑如何最小限度地改变现有参数,使这个方案成为最优的方案．如果说“正问题”的研究有助于一个新系统的设计和确定,那么“反问题”的研究对改善现有系统的性能具有重要的意义．本文以数学规划为工具,研究单台机器以带权总完工时间为优化目标的排序问题1Ⅱ∑wjCj关于权的反问题,在不同范数下的情况下给出最优解,并研究不带权的情况1Ⅱ∑Cj关于加工时间的反问题及其最优解．     

Estimation of power outage size based on the dominating differential equation

This paper describes a method to estimate how much power will drop after severe generation outage. When a large generation outage occurs, system frequency plummets to an unacceptable frequency level. Frequency drop affects both customers and generation systems. Thus adequate and quick load-shedding must be done to prevent problems. To institute any load-shedding policy effectively, the size of the generation outage must be precisely estimated in a very short time. So far, several methods have been proposed to estimate the power outage amount by measuring the decaying frequency variations that are obtained at each local bus. These methods are easily applied, but cannot be expected to provide good results in real power system operations because of the noises that are a part of decaying frequency variations. To cope with this problem, a new estimation method based on one that uses the dominating differential equation is proposed in this paper. The most precise estimation at this point is obtained by using additional factors, such as the sine wave included in the decaying frequency fluctuations and considered as a part of the equation. Simulation studies on a model power system consisting of five generating stations and four load points show that the newer method is encouraging. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (3): 39–49, 1997     

Microwave imaging: Reconstructions from experimental data using conjugate gradient and enhancement by edge-preserving regularization

A method for reconstructing the complex permittivity profile of lossy dielectric objects from measured scattered far-field data is presented. An iterative reconstruction algorithm based on a conjugate gradient method is derived from an integral representation of the electric field and applying a moment method solution. Results obtained from experimental data are shown for both known and unknown targets. Then, a new regularization procedure is developed to enhance the quality of the reconstruction. This method, based on a Markov random fields approach, models the object to be reconstructed by homogeneous areas separated by borderlike discontinuities. Finally, the enhancement is shown by the reconstruction of a polystyrene square cylinder. © 1997 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 337–342, 1997