Function-class decomposition: a hybrid software engineering method

In addition to offering a simple yet powerful method for decomposing a system, function-class decomposition (FCD) produces an architecture that is more supportive than traditional object-oriented decomposition for several software engineering tasks. A hybrid method that integrates structured analysis with an OO approach, FCD identifies classes in parallel with decomposing the system into a hierarchy of functional modules. Recently, developers extended FCD to integrate UML concepts. Useful for partitioning a system for distribution, the FCD hierarchy provides a framework for controlling development in a distributed software engineering environment. It also helps identify and integrate components in component-based development and supports the system life-cycle maintenance phase. Further, FCD addresses many of the initial analysis and design problems inherent in large and complex OO systems. The authors' experience with testing FCD on several applications validates its compatibility with OO methodologies and modeling techniques     

Per-queue stability analysis of a random access system

We have extended our previous studies (2000) of the system stability of buffered ALOHA systems to study an individual queue's stability, i.e., per-queue stability. The main result obtained in this work is a necessary and sufficient per-queue stability condition, which can be computed analytically only for several cases. For other incomputable cases, we evaluated several inner and outer bounds. They are generally quite tight for not-so-asymmetric systems     

测定外延层电阻率的面接触方法研究

评论了美国科学家C.C. Allen等于1966年发表的“测定外延层电阻率的点接触方法”之论文的局限性,从而提出了本方法。本方法从理论上解一维Poisson方程并与C.C。Allen法的公式相比较,获得某些公式。文中导出了面接触方法雪崩击穿电压V_(Ba)~∞(V)及点接触方法雪崩击穿电压V_(Bp)~∞(V)的比值为V_(Ba)~∞=0.456;同时还导出了点接触方法外延层耗尽层宽度为t_(min p)(μm)和面接触方法外延层耗尽层宽度t_(mina(μm)的比值为t_(minp)/t_(mina)=2.565。在实践上,为证实两种模型的功能,利用两种探针进行了对比测试。一种是通常被采用的点接触锇尖探针:另一种是利用φ0.8±0.1mm的银针,在银针顶上吸上φ0.4±0.1mm的汞球,以实现面接触。理论和实验吻合良好。     

Phase-error-free quadrature sampling technique in the ultrasonic B-scan imaging system and its application to the synthetic focusing system

The quadrature sampling technique as a means of detecting the envelope of RF waveform in the baseband is well known. If this technique is applied to a focused ultrasound imaging system using an array transducer, whether it is a synthetic or nonsynthetic focusing system, unwanted phase terms appear in the expressions of the inphase and quadrature components of the baseband signal when an appropriate delay time is introduced to each channel signal for the purpose of focusing. The expressions of the inphase and quadrature components from the point of focusing are derived and analyzed in detail, and a scheme to eliminate the unwanted phase terms is proposed. The resulting phase-error-free quadrature sampling technique is applied to the synthetic focusing system; a system block diagram together with the simulation and experimental results are presented.     

Micromachining process simulation using a continuous cellularautomata method

In this paper, we present results on the development of an anisotropic crystalline etching simulation (AGES) program based on a continuous cellular automata (CA) model. The program provides improved spatial resolution and accuracy compared with the conventional and stochastic CA methods. Implementation of a three-dimensional (3-D) dynamic CA technique provides increased simulation speed and reduced memory requirement. The first AGES software based on common personal computer platforms has been realized for simulation of micromachining processes and visualizing results in 3-D space. The software is uniquely capable of simulating the resultant profile following a series of micromachining steps, including surface passivation, reactive ion etching, as well as wet chemical bulk etching. A novel method for accurately obtaining the etch-rate diagram of anisotropic etching using both experimental and numerical techniques has been developed     

A MODIFIED METHOD FOR SUPERVISOR SPECIFICATION AND SYNTHESIS OF A CLASS OF DISCRETE EVENT SYSTEMS

In this paper, a model‐refining method is proposed to alleviate the complexity involved in specification interpretation of DES control problems. The legal constraint language is defined in terms of illegal states and events in contrast with constructing the automaton of the specification language. This method could provide a more intuitive view of the DES control problem and would be suitable for practical implementation. Two examples, which have commonly been used in the literature, are employed to show the efficiency of the proposed method. Further, under this framework, it is shown that the supremal controllable sublanguage can take a simpler form based on the concept of an illegal state set. A state‐based supervisor synthesis procedure is presented, and a simple example is provided.     

Preparation of bao-pbo-nd2o3-tio2 powders by hydrothermal synthesis

Homogeneous and nano-sized BPNT [(Ba_1-xPb_x)Nd₂Ti₅O₁₄] powders were prepared under various hydrothermal conditions. Crystallinity and homogeneity of the synthetic powders were investigated. The microwave dielectric properties of the filters prepared with hydrothermal powders were compared with those of the filters prepared with conventional powders. The microwave dielectric properties of the filter prepared with the hydrothermal powders were also better than those of the filter manufactured with the conventional powders. The dielectric constant, quality constant and temperature coefficient of resonance frequency of hydrothermally prepared filter under optimum condition and measured at 3.5 GHz around were about 93, 6067 and 0 ppm/°C, respectively.