热成形过程微观组织模拟研究进展

金属在热成形过程中微观组织发生诸如晶粒长大、再结晶等一系列的复杂变化,会直接影响加工过程与产品的力学性能。对近年计算机技术在热成形微观组织演变模拟方面的研究进展做了比较全面的评述,比较了相关的微观组织模拟方法,分析了利用各种模拟技术所取得的研究成果。     

Compacity influence in reorganization of two dimensional granular packings: Numerical model

Rearrangements (movements of disks) of different sizes are observed before the avalanche onset while studying avalanche process in 2D packings of disks of diameter d. A stochastic cellular automata model based on experimental observations is proposed to understand the influence of local packing fraction in the appearance of rearrangements in a two dimensional packing of disks. In numerical simulations, rearrangements of different sizes are also observed and evolution of the packing fraction is studied. The cellular automata retrieves experimental results when it considers a range of influence for rearrangements larger than 9d. Rearrangements are also found to be responsible for the decreasing of the system global packing fraction in discrete steps.     

变电站GPS授时装置实时定时标检测方法探讨

变电站自动化系统大多采用全球定位系统（GPS）授时装置保障智能电子设备（IED）之间的时间同步,通常通过时频的方式检测其输出信号的准确性。文中提出了一种新的检测方法作为补充和完善,其核心是:应用可控的实时GPS对时脉冲,控制指定时刻的时标脉冲输出和开关的动作,检测GPS授时装置输出信号的准确性和正确性,既可检测GPS授时装置输出信号的实时准确性,也可检测输出信号携带的时间编码信息的正确性。     

用Al-Ferron逐时络合比色法研究聚合硅酸硫酸铝的结构形态

利用Al-Ferron逐时络合比色法分析了聚合硅酸硫酸铝液体样品及其稀释后的水溶液在各种条件下的铝形态。结果表明：聚合硅酸硫酸铝液体样品中含有约占总量1／3的多羟基配合物,且受碱化度影响很小;稀释和提高pH值使聚合硅酸硫酸铝趋于聚集成更大的分子;水中杂离子则使聚合硅酸硫酸铝的结构形态随pH值的变化幅度减小,多羟基配合物组分增加。     

Design and Implementation of a Flexible Manufacturing Control System Using Neural Network

Design and implementation of a sequential controller based on the concept of artificial neural networks for a flexible manufacturing system are presented. The recurrent neural network (RNN) type is used for such a purpose. Contrary to the programmable controller, an RNN-based sequential controller is based on a definite mathematical model rather than depending on experience and trial and error techniques. The proposed controller is also more flexible because it is not limited by the restrictions of the finite state automata theory. Adequate guidelines of how to construct an RNN-based sequential controller are presented. These guidelines are applied to different case studies. The proposed controller is tested by simulations and real-time experiments. These tests prove the successfulness of the proposed controller performances. Theoretical as well as experimental results are presented and discussed indicating that the proposed design procedure using Elman's RNN can be effective in designing a sequential controller for event-based type manufacturing systems. In addition, the simulation results assure the effectiveness of the proposed controller to outperform the effect of noisy inputs.     

三维弯曲井眼钻柱接触非线性问题求解方法

目前研究钻柱与井壁多向接触问题普遍采用罚函数法、间隙元法、形式刚度法和放松约束法等,其计算速度慢,难以满足工程应用要求。通过建立三维弯曲井眼钻柱有限元模型和钻柱与井壁接触碰撞的定解条件,利用元胞自动机的基本理论,提出了一种基于元胞自动机的钻柱多向接触非线性有限元方程的求解方法。该方法具有编程简单、收敛速度快等优点,能够较好地解决钻柱在三维弯曲井眼中与井壁接触碰撞的复杂边界条件问题,适用于三维弯曲井眼钻柱接触非线性问题的求解。     

自动机及形式语言理论在网络分析中的应用

文中应用自动机及形式语言理论对网络流进行了描述,并给出了计算网络最短路径的两种方法。     

The formal definition of semantics by string automata

An abstract machine called a string automaton (SA) is introduced in this paper. SAs are motivated by the need to formally define the semantics of programming languages in a manner accessible to the users of the language. The SA notation can be used to represent functions and computations in a clear, concise, graphical, and natural manner. After the class of SAs has been formally defined, it is shown how logic modules (resembling hardware circuit elements) and function modules (which define functions) can be expressed by SAs. Networks of SAs and their application to the construction of parsers is discussed. The definition of the language and hardware components of an interactive programming system by means of SAs is outlined.     

Pregnancy rates after timed AI of heifers following removal of intravaginal progesterone inserts

Reproductive performance of dairy heifers was compared for each of 2 synchronization protocols: The first group of 54 heifers was synchronized using intravaginal progesterone inserts (CIDR) plus estradiol cypionate (ECP) on d 0, PGF(2alpha) on d 7, and ECP again on d 8 (CIDR-ECP); a second group of 56 heifers was synchronized using CIDR and ECP on d 0, PGF(2alpha) on d 7, and GnRH on d 9 (CIDR-GnRH). All heifers received timed artificial insemination (TAI) at 48, 56, or 72 h after CIDR removal on d 7. Pregnancy diagnosis was conducted by ultrasonography 32 +/- 1 d post AI to confirm pregnancy and at 60 +/- 1 d post AI to determine embryo survival. Ovaries were monitored by ultrasonography daily from d 0 to 7 and twice daily from d 8 to ovulation to examine emergence of a new wave of follicles, size of the ovulatory follicle, and timing of ovulation on 15 heifers per protocol. New follicular development was detected 3.7 +/- 0.2 d after CIDR insertion. Heifers receiving CIDR-ECP had a shorter interval from CIDR removal to ovulation than heifers receiving CIDR-GnRH (63.8 +/- 3.0 vs. 71.6 +/- 2.3 h, respectively); however, ovulation occurred 39.8 +/- 3.0 h after ECP or 23.6 +/- 2.3 h after GnRH. Diameters of ovulatory follicles did not differ between treatments. Overall pregnancy rate for synchronized heifers was 60.1%, and embryo survival was 98%. Pregnancy rate for heifers synchronized with CIDR-ECP was 63.0% and similar to that in heifers synchronized with CIDR-GnRH (57.1%). Pregnancy rate was affected by time of AI for heifers synchronized using CIDR-ECP but not for those synchronized with CIDR-GnRH. Heifers in the CIDR-ECP group that were inseminated 56 h after CIDR removal had a higher pregnancy rate (81.0%) compared with heifers inseminated 48 (66.7%) or 72 h (50.0%) after CIDR removal. Either ECP or GnRH used in a CIDR-based TAI program in dairy heifers can achieve acceptable reproductive performance.     

混合投影时序逻辑与混合系统的形式化验证

为了描述混合系统的性质和行为，10多年来，各种时序逻辑，如Hybrid Temporal Logic等相继出现。这些时序逻辑适用于刻画混合系统的性质和规范，但不适宜表示描述系统的实现模型。本文定义了一个混合投影时序逻辑（Hybrid Projection Temporal Logic，简称HPTL），既能刻画混合系统的性质，又能表示混合系统的实现。这样，混合系统的验证就可以很方便地在统一的数学模型框架下进行。同时，给出了HPTL的基本的逻辑等价式系统和一个用HPTL进行混合系统验证的实例。