Automated minimax system modeling†

This paper investigates the- feasibility of automated design of lower-order models for high-order systems where the order of the model can be increased efficiently according to desired performance criteria. The modelling can be done for a variety of objectives with or without constraints, so that a realistic on-line or off-line design can be achieved to satisfy a set of arbitrary transient and steady-state response specifications. Suitable examples are chosen to illustrate the modelling procedure.     

BOOK NOTICES

In this paper, a transformation technique, capable of converting certain classes of time dependent systems into equivalent systems with time invariant properties, has been presented. The response of the resulting time invariant system which is readily arrived at, can be transformed with the aid of the transformation laws to obtain the response of the given time dependent system.     

ECONOMIC DISPATCH USING A CONSTANT SENSITIVITY MATRIX

Abstract

This paper presents a method for economic dispatch which reduces involved calculations of the penalty factors. In this paper penalty factors are generated using some of the columns of the sensitivity matrix which reduces the computation time. The sensitivity matrix used is simply the inverse of the constant Jacobian of the modified Newton-Raphson load flow. This method gives accurate values for the penalty factors which are used to solve the coordination equations. The proposed method is validated by testing on different IEEE test systems and the relevant results are presented.     

用于HRP测定的一种主动式PDMS微混合器

微米尺度下的生物流体混合是生物微机电系统(BioMEMS)和分析化学等领域研究的重要问题之一,目前的混合方式多以被动式自由扩散为主,存在流体混合效率不高的现象.针对该问题,设计了一种主动式聚二甲基硅氧烷(PDMS)微混合器.该装置利用脉冲气体对多个PDMS微隔膜进行顺序驱动,可实现微混合室中不同液体的快速混合和反应.同时,基于鲁米诺.过氧化氢体系的化学发光反应机理,以辣根过氧化物酶(HRP)作为催化剂,进行了微混合器最佳工作条件研究,基于HRP化学发光分析法和L25-5-6正交实验,确定出微混合器化学发光分析法的最优实验条件组合.并在此实验条件下完成了HRP的微量测定.实验结果表明,目前检测体系下线性范围为2.05×10-9mol/L～2.05×10-8mol/L,检测限为2.05×10-9moL/L,检测反应时间小于2 min,可满足生物医学和分析化学领域对于物质测定方面的微量、快速的检测要求.     

Gelation of Beef Heart Surimi as Affected by Antioxidants

Oxidation of proteins (carbonyls) and lipids (TBARS) in beef heart surimi-like materials during preparation and storage (2°C) was inhibited by propyl gallate (0.02%) or α-tocopherol (0.2%). Inhibition of oxidation did not affect surimi gel property (storage modulus, G'). Storage promoted oxidation of proteins in 0.2% ascorbate-washed mince, leading to increases in peak (～ 55°C) and final (70°C) G' of thermally induced surimi gel. Protein carbonyls in stored surimi and its sol (salted), as well as TBARS of the sol, strongly correlated with both peak and final G of gels. Incorporation of tripolyphosphate into washed mince promoted gelation whether the surimi-like material was oxidized or not.     

A SOLID STATE RESISTANCE CONTROLLER FOR 3-PHASE SLIP-RING INDUCTION MOTOR

ABSTRACT

A solid state rotor resistance controller incorporating triacs for varying the speed of 3-phase slip-ring Induction motor delivering a constant load torque is presented. Using this controller, it is possible to vary the speed of the motor continuously from a definite minimum speed to a definite maximum speed. The controller is simpler and more reliable compared to phase controlled or chopper controlled resistance controllers.     

AZ31B镁合金及其纳米复合材料的滑动磨损行为(英文)

采用复合铸造工艺制备AZ31B镁合金及其纳米复合材料,再对所得材料在350°C进行热挤压。采用标准的销-盘式摩擦磨损试验机对AZ31B镁合金及其纳米复合材料的室温滑动磨损行为进行研究。实验条件为法向载荷10N、滑移速度0.60~1.2m/s、滑移距离2000m。采用SEM观察来研究磨损表面的磨损机理。通过构建一个线性回归模型来研究试验参数对磨销磨损率的影响。与AZ31B镁合金相比,由于增强体的作用而导致的硬度增强使复合材料表现出低的磨损率。犁削、犁沟、分层和氧化构成混合的磨损机理。     

Raman Spectroscopy of Monolayer-Type Catalysts: Supported Molybdenum Oxides

Oxides of the group VIb metals (Cr, Mo, W) and oxides of vanadium, rhenium, and niobium supported on a second high-surface-area metal oxide such as Al₂O₃, TiO₂, Si0₂, ZrO₂, and so forth are recognized as industrially important catalysts or catalyst precursors for various reactions [1–11], These materials frequently have been described as so-called monolayer catalysts based on a structural model which assumed spreading of the active oxide over the support surface. These catalysts have been investigated by a variety of techniques, conventional bulk sampling techniques as well as by surface-sensitive electron and ion spectroscopies, in an attempt to elucidate the nature of the catalyst surface species, and to study the coordination environment of the active metal center(s). Electronic spectroscopy gives rise to broad bands and the spectra are less informative than vibrational spectra. In addition, although techniques such as Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) are highly surface sensitive (with typical sampling depths of 1–2 nm), only indirect evidence concerning coordination environment can generally be obtained.     

Limiting conditions in a gear-shaping process

A gear-shaping process is used to cut cylindrical gears, both external and internal, with a pinion type of cutter. However, certain ‘inherent errors’ are present in the process which limit the range of the number of teeth on the gear to be cut. This paper deals with the analysis of inherent errors and suggests guidelines to avoid such errors, taking into account the effect of tip-relief angle     

A NOVEL METHOD FOR FILTERING AND RANKING OF CRITICAL CONTINGENCIES

ABSTRACT

A reliable and simple method is presented in this paper for filtering and ranking of critical contingencies. Infinite norm is used for filtering of critical contingencies and performance indices which reflect transmission line overloads, load voltage levels and generator reactive capabilities are used to rank the identified critical contingencies in a decreasing order of severity. Secondary outages are also included in the proposed method. Outage simulation technique is used to simulate the outage of a line or a transformer. A constant sensitivity matrix which is the inverse of the constant Jacobian of the modified Newton-Raphson load flow method is used in these studies. The proposed technique has been validated by testing it on various test systems and relevant results are presented