REALIZATION THEORY OF DISCRETE-EVENT SYSTEMS AND ITS APPLICATION TO THE UNIQUENESS AND UNIVERSALITY OF DEVS FORMALISM

Many man-made systems have discrete event nature. Many modeling formalisms for discrete-event mechanisms have invented and been used for many problems. Among those models, the DEVS formalism is to provide natural and universal models in some sense.

This paper first provides a realization theory of general discrete-event systems. That is, a behavioral definition of discrete-event system is defined, and then a state transition function of the system is constructed. Based on the realization, the uniqueness problem of representations for discrete-event systems is positively solved. Furthermore, as an application of that solution, this paper shows both the fact that a legitimate DEVS with surjective internal transition function is unique up to isomorphism in the class of state representations of the state system defined from the DEVS, and the fact that any discrete-event system has a DEVS realization. In this sense the DEVS modeling facility has the uniqueness and universality in modeling discrete event mechanisms.     

频率步进探地雷达及其在地雷探测中的应用

频率步进方法是探地雷达技术的工作体制之一,与时域无载频脉冲体制的探地雷达技术相比,在探测性能上具有较多的优越性.本文在简述其工作原理的基础上,介绍了作者研制的一种频率步进探地雷达系统,该系统主要用于对地雷目标进行三维成像探测.在研制该雷达系统过程中,对已有的反对称Vivaldi天线提出了改进设计.实验测量结果表明,本文研制的反对称Vivaldi天线与传统的同类天线相比,性能更加优越.同时,为了得到更加清晰的地雷图像,本文还分别引入了f-k偏移成像方法和合成孔经雷达(SAR)处理技术对雷达探测信号进行处理,得到了满意的结果.探测实例表明,频率步进探地雷达系统能够实现对浅层地下地雷目标的高分辨率三维成像探测.     

薄层色谱画像解析法快速判定鱼肉的脂质氧化度

为了快速判定鱼肉的脂质氧化度,建立薄层色谱画像(thin layer chromatography image,TLC-i)解析法快速测定鱼类氧化生成的极性化合物含量。取黄鳍金枪鱼油0.5μL点样于硅胶板上,用正己烷-乙醚-醋酸(30∶70∶1,V/V)的混合液展开12 min后,3%醋酸铜磷酸溶液喷雾显色,150℃加热15 min后,将氧化生成的极性化合物通过面积分析软件进行半定量分析。结果表明,此方法测得的极性化合物含量与常用的过氧化值(peroxide value,POV)、羰基值(carbonyl value,CV)相比,具有较好的相关性,相关系数分别为0.993 8和0.972 5。将此方法用于判定远东多线咸鱼在4℃贮藏期间的脂质氧化情况,发现极性化合物含量与POV具有较好的正相关性(R~2=0.962 5)。将此方法用于判定盐渍红鲑在-5℃贮藏期间的脂质氧化情况,发现极性化合物含量与a*值具有较好的负相关性(R~2=-0.822 9)。结果表明,该方法具有简单化、快速化、微量化、可视化的优点,且不需要昂贵的设备,适合鱼肉脂质氧化度的快速评价。     

Spectroscopic Measurement of Shock Waves in an Arcjet Plasma Expanding Through a Conical Nozzle

A diamond-shaped shock wave was created in a helium arcjet plasma. Visi- ble/ultraviolet emission spectroscopy was used to investigate the condition for the formation of stable shocks and to determine characteristics of the plasma. Dependence of the position of the shock front on the gas pressure in the expansion region was investigated. It was found that the shock wave arises from the collision of plasma particles and residual neutral atoms in that region. Continuum and line spectra of neutral helium were measured, from which the electron temper- atures were derived. The electron density was deduced from the Inglis-Teller limit of the He I 2p 3 P-3d 3 D series. The temperature and density were found to have almost constant values of 0.2 eV and 8.5×10 13 cm 3 , respectively, across the shock front.     

Electron transport behaviors across single grain boundaries in <Emphasis Type="Italic">n</Emphasis>-type BaTiO<Subscript>3</Subscript>, SrTiO<Subscript>3</Subscript> and ZnO

In some electroceramic materials, their unique electrical properties are due to potential barriers, i.e., double Schottky barriers (DSBs), formed at grain boundaries. So far, some researchers have revealed that the electrical properties of DSB are closely related to grain boundary characters, especially grain boundary coherency. For example, highly coherent boundary does not give PTCR or varistic property, while random types exhibit clear resistivity jump or abrupt current increment. Therefore, a concept of grain boundary design will be required for future device manufacturing, even in bulk materials. But it has not been clarified yet why the electron transport behaviors depend on them. In order to address this question, it is necessary to carry out a systematic experiment focusing on single grain boundaries using well-defined bicrystals.In the present study, we have summarized our studies with a special interest in electron transport behavior across single grain boundaries for n-type BaTiO₃, SrTiO₃ and ZnO.     

A PROPOSAL FOR TREATMENT OF TURBULENT MIXING IN A TWO-PHASE SUBCHANNEL FLOW

We propose a practical method for the treatment of turbulent mixing rate in a two-phase subchannel flow in a hydrodynamic non-equilibrium state. Based on the assumption that the fundamental modes of the inter-subchannel fluid transfer in such a state are turbulent mixing, void drift, and diversion cross flow, the turbulent mixing rate is considered to be equal to that in the hydrodynamic equilibrium state that the flow will attain. The applicability of the method is examined by experiments concerning the axial variation in tracer concentration in a non-equilibrium flow without diversion cross flow. A good agreement is seen between the calculations and the measurements.     

THERMODYNAMIC STUDIES ON THE EXTRACTION OF ZINC(II)FROM HYDROCHLORIC ACID SOLUTIONS BY TRIOCTYLMETHYLAMMONIUM CHLORIDE IN VARIOUS DILUENTS

ABSTRACT

In the extraction of zinc(II) from hydrochloric acid solutions by trioctylmethylammonium chloride in various organic diluents such as benzene, chlorobenzene, o-dichlorobenzene, toluene, m -xylene, nitrobenzene, carbon tetrachloride and 2,2-dichloroethane, the heat change associated with zinc(II) extraction has been examined by calorimetry. In the case of benzene used as diluent, it is confirmed that the heat change detected can be interpretated as the summation over the change in enthalpies for the relevant steps to the extraction of zi(II), taking the change in enthalpy obtained from the temperature-dependence of the distribution coefficient into account. Applying this approach of zinc(II) extraction for other diluents, it is found that the distribution of zinc (II) between aqueous and organic phases can be explained very well by assuming a regular solution.     

DILUENT EFFECT ON THE EXTRACTION OF URANIUM(VI) FROM HYDROCHLORIC ACID SOLUTIONS BY TRIOCTYLMETHYLAMMONIUM CHLORIDE

ABSTRACT

The extraction of uranium(VI) from hydrochloric acid solutions by trioctylmethylammonium chloride (TOMAC) has been examined using various diluents such as benzene, chlorobenzene, o-dichlorobenzene, toluene, m-xylene, nitrobenzene, carbon tetrachloride, chloroform and 1,2-dichloroethane. It was found that by assuming a regular solution, the distribution coefficient and the enthalpy change associated with the metal extraction can be expressed in terms of the solubility parameter of TOMAC, diluent and the complex formed in the organic phase and their molar volumes. Additionally an empirical relation holds between distribution coefficient and the viscosity of diluent. Further results for the extraction of divalent manganese, cobalt, copper, zinc and cadmium from hydrochloric acid solutions by TOMAC are investigated in comparison with those of uranium(VI).