污染物在黏土中的非线性扩散特性

针对溶质运移测试中运移参数提取困难、方法不统一的现状,基于溶质在土粒上的质量分数,定义了一个新的非线性吸附模型;推导了非线性吸附情况下溶质运移的控制方程,并用最小二乘法原理编制运移参数的反演程序;用一维土柱静态扩散法测试Pb(Ⅱ)在高岭土柱中的扩散特性,用非线性吸附模型成功提取出运移参数.结果表明：非线性扩散理论比线性扩散理论能更好地解释实验现象;Pb(Ⅱ)在高岭土/水之间的吸附特性近似符合Freundlich模型;Pb(Ⅱ)在高岭土柱中的扩散系数为0.086 8～0.105 8 cm2/d,且呈现出随着溶质体积浓度的减小而增大的非线性;土柱扩散法测得Pb(Ⅱ)在高岭土柱中的单层吸附容量为0.001 77～0.002 36,明显小于Batch法所得的吸附容量;高岭土作为Pb(Ⅱ)的屏蔽材料是可行的,但增加土样的干密度会降低土样吸附污染物的能力.     

SCREENING OF RESISTANT TRIACYLGLYCEROLS TO THE PANCREATIC LIPASE AND THEIR POTENTIALITIES AS A DIGESTIVE RETARDANT

A gradual retarding of lipid digestion and absorption might contribute to preventing the visceral fat accumulation and obesity in humans. The lipolysis rates of different triacylglycerols (TAGs) by pancreatic lipase in vitro were studied in order to find suitable components as a retardant for lipolysis. Several TAGs containing longer acyl chains than stearic acid or containing unsaturated fatty acids whose double bonds are located closely to the carboxyl group like petroserinic and γ-linolenic acid showed significantly lower lipolysis rates as compared with triolein (OOO) control. Most of these resistant TAGs contributed to decelerating the lipolysis rate when replaced at 10% into the OOO control. Especially, 1-behenoyl-2,3-dioleoyl- rac -glycerol (BOO) was comprehensively thought to be a suitable TAG as a digestive retardant among them. Each 10% replacement of edible oils by BOO gave 15% to 30% reduction of the lipolysis rate in vitro . Resistant TAGs that are able to melt or solubilize into liquid oil at body temperature have some potential as a digestive retardant for lipids.

PRACTICAL APPLICATIONS

Visceral fat accumulation and obesity in humans are thought to be correlated with the rate of lipid digestion and absorption. The entire rate of lipid absorption is controlled by their partial replacement with some digestive retardant. Resistant triacylglycerols may have some potential as a digestive retardant of lipids. Results of the present study propose a new fat system for foods with antiobesity effect.     

Charge and Discharge Control to Save Regeneration Energy for Overhead Line and Energy Storage Device Hybrid Power Source Three‐Level Inverter

Hybrid power source three‐level inverter is proposed as a main circuit system with energy storage device for increasing regenerative power. This paper proposes a charge and discharge control method to utilize the regenerated energy. The proposed method is verified by experimental tests with a scaled‐down model and numerical simulation.     

Robust control for a constantly rising temperature system (Hm control approach)

Thermoluminescence dating has attracted the attention of geology and archaeology researchers as a new method. This method requires a heating device to raise the temperature of the specimens at an exact rate. This paper describes the design method of a control system that can achieve this goal. This control system lends to be unstable because of the existence of the parameter perturbation and dead time. In this paper, the perturbation and dead time are treated as perturbations of a nominal plant regarded as a first-order lag time system. Improvement of tracking characteristics in the low-frequency domain and robust stability in the high-frequency domain of the control system are achieved by using the solution of the mixed-sensitivity problem that is a kind of H^∞ control theory. Experiments verify the effectiveness of this method.     

Pooled Log Periodogram Regression

Estimation of the memory parameter in time series with long range dependence is considered. A pooled log periodogram regression estimator is proposed that utilizes a set of mL periodogram ordinates with L →∞ rather than m ordinates as in the conventional log periodogram estimator. Consistency and asymptotic normality of the pooled regression estimator are established. The pooled estimator is shown to have smaller asymptotic variance, but larger asymptotic bias, than the conventional log periodogram estimator. Finite sample performance is assessed in simulations and the methods are illustrated in an empirical application with inflation and stock returns.     

EFFECT OF PARAMETER CHANGES ON THE PERFORMANCE OF SOLID ROTOR THREE-PHASE RELUCTANCE MOTORS

ABSTRACT

An adequate understanding of the close relation existing between performance characteristics and machine parameters is essential for designing any reluctance motor.

The present paper deals mainly with how the steady-state stability of small solid rotor three-phase reluctance motors is affected by the machine parameters. The effects of certain typical machine parameters have been quantitatively demonstrated, which may be instrumental in designing the motor.

To confirm the results obtained, a comparative review of calculated and experimental values is also presented for a number of different machines.     

Estimation of kernel function of non-linear system by gaussian non-white noise

The kernel function of a non-linear system characterizes the properties of that system. The kernel function is well developed in the case of gaussian white noise. However in practice it is often necessary to apply an input of gaussian non-white noise in the control of biological systems. Although some methods have been developed that use gaussian non-white noise they do not have a simple computation. Furthermore, the kernel function obtained by these methods is not stable in practice. Here, we develop a gaussian non-white method based on a smoothing operation on the kernel function. The amplitude of the kernel function is then derived as a parameter, that characterizes the non-linear system. The kernel function obtained by a traditional method is compared by means of simulation with the smoothing method developed here.     

MICROPROCESSOR BASED NONLINEAR EXCITATION CONTROLLER FOR SYNCHRONOUS MACHINES

ABSTRACT

The synchronous machines in power systems have the excitation systems of field winding to improve the transient stability of power systems. The synchronous machines are nonlinear systems, however, the excitation systems have been designed based on linearized systems, because the stability analysis of nonlinear systems is difficult and the generalized control method of nonlinear systems has not been developed yet.

This paper proposes a nonlinear excitation controller for synchronous machines in power systems. For the sake of simplification of the nonlinear state feedback control, this paper considers both the transient stability and the suppression of the rotor swings in transient conditions. The effect of the automatic voltage regulator (AVR) for the synchronous generator is not discussed here. This controller is designed based on Lyapunov's direct method that can directly judge the stability of nonlinear systems. The usefulness and validity of the proposed excitation controller are confirmed by numerical simulations and experiments. The microprocessor based generator excitation system that consists of a nonlinear controller, state variable detector, and PWM inverter, is constructed. The nonlinear excitation controller can improve the transient stability of synchronous machines.     

QUICK AND PRECISE POSITION CONTROL OF ULTRASONIC MOTORS WITH TWO CONTROL INPUTS

ABSTRACT

Ultrasonic motor (USM) has an excellent performance and many useful features. Since this motor is superior in holding torque and high response characteristic, it has been expected to use as position servomotor for small motors.

There have been reported some mathematical models of the ultrasonic motor. however, these models are too complex to apply for control of the motor. Therefore position controllers based on PI control or fuzzy control have been proposed in recent years. It is difficult to control the ultrasonic motor with high-performance using such controllers, thus simple and convenient mathematical model is necessary for precise control.

This paper presents a new position control scheme of ultrasonic motor, it consists of a PI controller and an adaptive controller which compensates the speed characteristic variations with online parameter identification. Moreover, this system controls both driving frequency and phase difference in order to achieve a quick and precise position control. The effectiveness of proposed control.scheme is demonstrated by experiments.