一种新的ⅥA族化学反应振荡器：Na_2S_2O_8－KSCN－CuSO_4体系

一种新的ⅥＡ族化学反应振荡器：Ｎａ_２Ｓ_２Ｏ_８－ＫＳＣＮ－ＣｕＳＯ_４体系林娟娟，高庆宇，宋浩，黄振炎，赵学庄（南开大学化学系，天津，３０００７１）关键词化学振荡，非线性化学反应，过硫酸盐，硫氰酸盐自经典的均相ＢＺ化学振荡反应体系的发现及提出耗散结构...     

Cr(VI) and Cu(II) removal from aqueous solution in fixed bed column using rice bran; experimental,statistical and GA modelling

Rice bran, a green and low-cost adsorbent, is used for Chromium (VI) and Copper (II) remotion from its aqueous solution. The influence of different process parameters in a fixed-bed on the removing efficiency has been investigated. The results show that the removal efficiency is higher at a minimum flow rate, low metal ion concentration, and higher bed height. The adsorption studies show that the rice bran has a better affinity to Chromium (VI) than Copper (II). Different kinetic models are used for the prediction of the column performance. This study shows that rice bran could be a potential and eco-friendly adsorbent for chromium (VI) and copper (II) removal and is suitable for developing countries like India. Multiple linear regression and ANN-based genetic algorithm modelling have been applied successfully to predict both metal ions' percentage removal separately.     

Improving the neural network method for finite element model updating using homogenous distribution of design points

In developing a neural network technique for a finite element model updating, researchers have been shown that the number of training samples and their quality, significantly affect the accuracy of the NN predication. In this study, based on the genetic algorithm (GA) method, we reduce the number of analyses required to develop the training pairs and reduce the amount of time for training the NN. In the other words, a uniform distribution of design points inside the design space will be obtained by means of this approach. To validate the efficiency of GA sample selection, random generation (RG) method is used for comparison. Two comparisons are made based on a numerical and experimental example. One is updated from 10 degrees of freedom lumped parameters system and the other is updated from a free–free beam using test data. The results indicate that the GA sample selection can reduce the number of training samples without affecting the accuracy of the NN predication. In our present study, also, the advantages of using frequency response function (FRF) data as input to the NN are kept and the drawback of having too many frequency points is overcome by the application of principal component analyses (PCA).     

高阶拟线性中立型偏泛函微分方程组解的振动性

1 引言 由于在人口动力学、生物遗传工程和化学反应过程等自然的和人为的过程中都存在滞后现象,因而偏泛函微分方程(组)的研究能更精确地揭示事物本质,同时能丰富微分方程(组)理论的研究。近十几年来,很多学者在泛函偏微分方程解的振动理论的研究方面作了大量工作,取得了许多成果。然而,关于泛函偏微分方程组解的振动性的研     

一步法设计单色仪凹面全息光栅

凹面全息光栅是光谱分析仪器的核心器件之一,其成像质量直接决定了光谱分析仪器的分辨本领。利用光程函数理论设计凹面全息光栅是一个繁琐的求解非线性方程组的过程,该过程分两步进行,每步需要求解四个非线性方程。分两步求解不但过程麻烦,还不可避免地引入了取舍误差,降低了最优参数的精度。为了解决该问题,本文提出了一种设计单色仪凹面全息光栅的新方法——一步法,该方法不但可以简化求解过程、降低最优参数的误差,还可以方便地控制整体像差的变化趋势。采用有较强全局搜索能力的遗传算法求解该方法中非线性方程的极值问题,并与传统的方法对比验证了该方法的可行性和正确性,结果表明,一步法不但在方法上比两步法简便,其设计结果还优于两步法。     

Performance Test of CW 300?GHz Gyrotron FU CW I

A 300 GHz CW gyrotron FU CW I has been developed and installed in the Research Center for Development of Far-Infrared Region, University of Fukui as a power source of a high frequency material processing system. Its performance was tested and the maximum power of 1.75 kW / CW has been attained at the beam voltage of 15 kV and the beam current of 1A. The maximum window power efficiency of 15.5% has been obtained at the cathode voltage slightly lower than 15 kV. This gyrotron is designed to deliver a Gaussian beam after mode conversion from the oscillation mode TE_22,8 in the cavity with a complex of an internal radiator and beam shaping mirrors. The detailed measurement with an infrared camera has confirmed that a Gaussian beam is radiated when the magnetic field strength B _c at the cavity is adjusted at a proper value. However, within a range of B _c , the output power is emerged into multiple directions, which suggests simultaneous oscillation of competing cavity modes.     

Noise-induced synchronous stochastic oscillations small scale cultured heart-cell networks

This paper reports that the synchronous integer multiple oscillations of heart-cell networks or clusters are observed in the biology experiment. The behaviour of the integer multiple rhythm is a transition between super- and sub- threshold oscillations, the stochastic mechanism of the transition is identified. The similar synchronized oscillations are theoretically reproduced in the stochastic network composed of heterogeneous cells whose behaviours are chosen as excitable or oscillatory states near a Hopf bifurcation point. The parameter regions of coupling strength and noise density that the complex oscillatory rhythms can be simulated are identified. The results show that the rhythm results from a simple stochastic alternating process between super- and sub-threshold oscillations. Studies on single heart cells forming these clusters reveal excitable or oscillatory state nearby a Hopf bifurcation point underpinning the stochastic alternation. In discussion, the results are related to some abnormal heartbeat rhythms such as the sinus arrest.     

Empirical pseudopotential band structure parameters of 4H-SiC using a genetic algorithm fitting routine

In this paper, the viability of using a genetic algorithm to find band structure parameters for empirical pseudopotential method (EPM) calculations is demonstrated by applying a genetic algorithm to find the EPM parameters for 4H-SiC. The form of the pseudopotential for 4H-SiC and the 19 form factors found by the genetic algorithm to fit the band structure to experimentally measured indirect energy gap and direct optical gaps are given. In addition, the effective masses for the conduction band minimum are extracted from the calculated band structure. It is shown that the genetic algorithm provides an effective, automated way to find parameters that give reasonably good fits to both the band gaps and the effective masses simultaneously.