GT系列运动控制器的二次开发

本文在“PC＋运动控制器”的开放式数控系统硬件构建的基础上，提出在数控代码查错解释软件功能模块中创建关系型数据库方法。使用这种方法来保存查错解释的结果，可提高数控代码编译和后续仿真执行的效率。     

串并联坐标测量机虚拟样机仿真验证的研究

将在UG中创建的串并联坐标测量机虚拟样机导入动力学仿真软件ADAMS中,用编译运行过程函数的方法,对用数学方法推导的测量机运动学解析解进行了仿真验证,证明该解析解表达式推导正确。该方法为机器人运动学分析提供了新思路。     

串并联坐标测量机虚拟样机仿真验证的研究

将在UG中创建的串并联坐标测量机虚拟样机导入动力学仿真软件ADAMS中,用编译运行过程函数的方法,对用数学方法推导的测量机运动学解析解进行了仿真验证,证明该解析解表达式推导正确.该方法为机器人运动学分析提供了新思路.     

基于Vega的岸边集装箱起重机视景仿真系统场景驱动

为了实现岸边集装箱起重机视景仿真系统中起重机、海洋和集装箱运输车的运动以及场景的驱动,首先根据岸边集装箱起重机工作过程确定场景驱动方案,基于Windows平台设置适合编译Vega应用程序的编译环境,应用Lynx界面进行系统初始化,在VC++中调用Vega库函数编程,实现场景的漫游,调用VegaPart类函数检测、获取及控制起重机DOF节点,实现起重机大车、小车运动,并结合岸边集装箱起重机的工作环境,通过Vega扩展模块和Path Tool工具,分别添加动态海洋和创建集卡运动路径,最终实现岸边集装箱起重机视景仿真系统中起重机和各运动体的驱动。     

基于单片机的信号发生电路仿真

文章通过实例具体介绍了Proteus在单片机仿真开发中的实践应用。使用Proteus软件的单片机仿真功能,对单片机输出占空比可调节的脉冲信号电路进行虚拟设计。应用Proteus元件库及创建环境模拟搭建仿真硬件电路模型,结合μVision2的软件编译环境,实现程序代码的功能验证。     

通用数控代码编译系统研究与实现

针对目前数控代码编译系统专用性及难维护等局限性 ,提出一种应用专用编译工具开发通用数控代码编译系统的方法。将高级语言式编译技术引入到数控代码编译过程中 ,应用专用编译工具LEX&YACC进行编译程序设计与开发 ,对传统数控代码编译技术加以扩展 ,将代码转换增加到其中 ,提出了系统定制的方法 ,从理论上建立了一种新的数控代码编译模式。提出“分层递进”树型数据处理模式和面向对象通用编译器设计方法 ,可对系统定制进行有效维护 ,保证系统运行的稳定性及可靠性。     

基于Pro/Toolkit的铝型材焊接接头库研究与开发

针对轨道车辆铝型材焊接接头缺乏标准化管理、重复建模等问题,设计开发了一个3D铝型材焊接接头库,实现了三维接头模型及其数据信息的有效管理。首先在Pro/E系统中创建了具有参数化功能的样板模型;然后利用Microsoft Access创建了数据库,用ADO数据库访问接口技术解决了与Pro/E系统之间的通信;最后在Visual C++编译环境下,调用Pro/Toolkit应用程序提供的相关函数,编制了菜单和用户操作界面。研究结果表明,该铝型材焊接接头库的建立方便了车体建模,还可以允许用户按需求扩展焊接接头库,实现了系列化设计,提高了设计效率。     

基于ADAMS、WTK的汽车操纵稳定性虚拟试验系统的研制

介绍了ADAMS／Car内部分析控制机理,在此基础上应用此软件进行了转向盘转角脉冲输入的汽车操纵稳定性分析试验,并对仿真结果进行曲线表示和分析说明。利用虚拟仿真软件包WTK在VC编译环境下创建了本虚拟试验系统,并应用ADAMS仿真分析结果曲线驱动本虚拟试验系统的汽车模型,实现了整个虚拟试验系统的动态仿真,从而为人进行主观评价操纵稳定性提供了一种新的实现方法。     

数据库编译数据的教学探究

数据库的主要功能就是进行数据的相关处理,包括编译数据、存储数据以及调用数据等等。其中,数据编译是数据库中关于数据处理的重点内容。通过对数据库的教学进行分析,讨论在数据库数据编译中的教学技巧与教学内容,探讨数据库编辑的原理,让学生更清晰地了解数据库的意义和实现。     

MOD300系统维修经验点滴

故障现象一: 在对其一回路模块组态后,进行编译,系统提示到上级编译,到整个控制器级编译后仍提示到上级编译,对整个数据库翻译后,下装到环境,打入环境名后系统提示环境名错,事实上环境名正确。     

Histochemical and ultrahistochemical localization of heavy metals in calf organs

Cadmium, zinc, selenium, and copper were administered, singly or in combination, orally or subcutaneously. Experiment I included 32 calves of both sexes; six received Cd (two groups), Zn, Cd, and Zn, and Cd and Se (two groups) and one group was a control. In Experiment II (21 bulls), three were given Cd, Cd, and Cu, and Cd and Zn, respectively, and one group was a control. For light microscopy, in Experiment I the highest amounts of silver granules were present in the samples of liver, small intestine, and vesicular gland of all the exposed groups; in Experiment II the most affected organs were liver, kidney, and small intestine. For electron microscopy, in Experiment I, after administration of Cd and Zn, the highest amounts of granules were seen in the cytoplasm of hepatocytes and cells of the proximal and distal renal tubules and the lowest amounts were found in glandular cells of the pancreas. Administration of Cd and Se resulted in the presence of large numbers of granules in the nuclei and nucleoli of spermatogonies. In Experiment II, ingestion of Cd and Zn in feed led to the appearance of highest amounts of granules in the nucleoli, nuclei, and cytoplasm of cells in testes, kidneys, and pancreas. Following Cd intake, the highest accumulation of granules was observed in the nucleoli of hepatocytes and cells of the proximal and distal renal tubules. Combined Cd and Cu produced the highest number of granules in cells of the proximal and distal renal tubules and in the nucleoli and nuclei of germinal epithelium.     

Extracellular breakdown of collagen by mice decidual cells. A cytochemical and ultrastructural study.

The interaction of antimesometrial decidual cells and collagen fibrils was studied by light microscopy and ultrastructural cytochemistry in fed and acutely fasted mice on days 9-11 of pregnancy. Fibrillar elements in the extracellular space consisted of collagen fibrils and filamentous aggregates (disintegrating collagen fibrils). Intracellular vacuoles exhibited typical collagen immersed in electron-translucent material (clear vacuoles) and faint cross-banded collagen immersed in electron-opaque material (dark vacuoles). Fibrillar elements showed extracellular acid phosphatase activity which was stronger in the region of mature decidua than in predecidual cells region in all animals; it was conspicuous in mature decidua of fasted animals. Intracellular acid phosphatase activity was observed in dark vacuoles and lysosomes, and was absent in clear vacuoles in all cells studied. Since acid phosphatase activity reflects the presence of lysosomal hydrolases in general, the results indicate that breakdown of extracellular collagen occurs by release of lysosomal enzymes by decidual cells and also by internalization of collagen for intracellular degradation in fed and fasted mice. Collagen breakdown may be part of the process of tissue remodeling in mature and predecidual regions, however, in mature decidua, collagen breakdown is enhanced and may therefore contribute to nutrition of the fetus, specially in acutely fasted mice.     

Differential expression of CD95, Bcl-2, and Bax in rat gastric chief and parietal cells

Apoptotic cell death is common in the inflamed gastric mucosa, but its role in the regulation of cell homeostasis in normal gastric mucosa is unknown. We investigated the expression of CD95, Bcl-2, and Bax and their roles in the regulation of apoptosis in normal rat gastric mucosa and in cultures of highly enriched rat chief and parietal cells by immunostaining, Western blotting, and FACS. In intact tissue CD95, Bcl-2, and Bax were localized predominantly in the glandular base region in chief cells. In freshly isolated cells, expression of CD95, Bcl-2, and Bax was much more pronounced in chief cells than in parietal cells. A lower intracellular Bcl-2/Bax ratio suggesting a higher susceptibility to apoptosis was noticed in chief rather than in parietal cells. In extended cultures of parietal and chief cells, Bax expression was upregulated and Bcl-2 expression was downregulated. These regulatory changes, presumably caused by in vitro effects, were not associated with an increase in spontaneous apoptosis. Treatment of chief and parietal cells with Fas-ligand induced apoptosis of all CD95 expressing cells. Expression of CD95, Bcl-2, and Bax predominantly in chief cells suggests that in this cell type regulation of apoptosis may differ from that in parietal cells. Binding of FasL with functionally active CD95 receptors on chief and parietal cells may be relevant for induction of apoptosis in inflamed gastric mucosa.     

Distribution of sex steroid hormone receptors in the avian brain: functional implications for neural sex differences and sexual behaviors

Developmental and seasonal changes in the production of androgens, estrogens, and progestins seem to control sex-specific differentiation and seasonal changes in appetitive and consummatory sexual behaviors of birds. This results in profound sex differences in the quality (sex-specific) or quantity (sex-typical) of behaviors such as courtship, territoriality, or copulation. Steroids affect the brain by binding to intracellularly located receptors. The same brain areas express androgen, estrogen, and progesterone receptors in male and female brains. Sex differences in these genetically determined patterns occur in the size of neuron populations that intrinsically express sex steroid receptors. Further permanent sex differences are subsequent to degenerative fates of receptor expressing neuron populations during ontogeny. Transient sex differences in receptor expression appear to be due to area-specific up- and down-regulation of receptor levels, reflecting transient changes in the level of circulating steroids, changes in environmental conditions, or in the physiological status of the individuals. In particular, intrinsic sex differences in the expression pattern of sex steroid receptors and steroid-independent regulation of the expression level of these receptors in the brain are limiting mechanisms for gonad-dependent sexual development and activities.     

五自由度机器人的结构设计及其控制

介绍了串联五自由度机器人的机械结构和机器人控制系统的设计.文中设计的五自由度机器人既可以用于实际生产,也可以用于教学和科研.用于实际生产既可以执行点位控制下的操作,也可以执行连续轨迹控制下的操作;用于教学和科研时,该机器人可用于机器人结构分析、机构运动学分析及机器人控制系统的教学演示和实验操作.它具有结构简单、操控方便等特点,而且可以做进一步的研发.     

Gender-related changes in the avian vasotocin system during ontogeny

The arginine vasotocin (AVT) system of the avian brain includes a sexually dimorphic part that extends from the caudal part of preoptic region through the medial part of the bed nucleus of stria terminalis (BSTm) to the lateral septum. It is composed of the parvocellular neurons located in the BSTm and the dense innervation of the medial preoptic region and lateral septum. In this part of the brain, AVT expression is stronger in males than in females in a few bird species investigated to date. This review focuses on the ontogeny of sexual differences in the vasotocinergic system of two gallinaceous species, domestic chicken and Japanese quail, and on the role of gonadal hormones in organizing during development and maintaining in adulthood these differences. Parvocellular AVT neurons become discernible in the BSTm of males and females during the second half of embryonic development. These cells undergo a profound and irreversible sexual differentiation during ontogenetic development. Recent findings demonstrate a dual role of estrogens in the organization and activation of sex differences in the AVT system. During the embryonic period of ontogeny, estrogens differentiate the AVT system in a sexually dimorphic manner in parallel with the differentiation of sexual behavior, while in adulthood estrogens, locally produced from testosterone in the male brain, activate AVT synthesis in the BSTm. The sexually dimorphic part of the AVT system is sensitive to a number of abiotic factors such as light, temperature, and water availability. It is suggested that sex dimorphic vasotocinergic systems could be implicated in processes of social recognition in various behavioral contexts.     

Sex differences in songbirds 25 years later: What have we learned and where do we go?

About 25 years ago, Nottebohm and Arnold reported that there are profound male-biased sex differences in volume in selected nuclei in telencephalic portions of the song control system. This review focuses on issues related to the cellular bases of these sex differences in volume and comparative studies that might elucidate the function of this variation between the sexes. Studies utilizing a variety of neurohistological methods in several different species to define the boundaries of two key telencephalic song nuclei HVc and the robust nucleus of the archistriatum (RA) all tend to find a sex difference in volume in agreement with Nissl-defined boundaries. Sex differences in volume in nuclei such as HVc and RA are associated with differences in cell size and cell number. Other attributes of the phenotype of cells in these nuclei are also different in males and females such as the number of cells expressing androgen receptors. Comparative studies have been employed to understand the function of these sex differences in the brain. In some songbird species, females sing rarely or not at all, and the brain nuclei that control song are many times larger volume in males than females. In other species, males and females sing approximately equally, and the brain nuclei that control song are approximately equal between the sexes. Recently, statistical methods have been employed to control for phylogenetic effects while comparing the co-evolution of traits. This analysis indicates that the evolution of sex differences in song has co-evolved with the evolution of sex differences in singing behavior in songbird species. Future studies should focus on the function of the smaller song control nuclei of females and investigate the role these nuclei might play in perception as well as in production. Microsc. Res. Tech. 54:327–334, 2001. © 2001 Wiley-Liss, Inc.     

The intracellular distribution of ions and water in rat liver and heart muscle

Local dry mass concentrations of intracellular compartments in rat heart muscle and liver cells were estimated by quantitative electron microscopy and X-ray microanalysis of ultrathin frozen-dried cryosections. The results were used to calculate elemental concentrations per litre of compartment water from the X-ray microanalytical data. Water fractions were between 80.3 ± 1.3% of wet weight in the decondensed chromatin and only 45.1 ± 1.7% in mitochondria of liver cells. The lowest water fraction in heart muscle cells was also found in mitochondria. The ionic concentrations found in the cytoplasm of liver cells and in the myofibrils are in accord with the electroneutrality rule and in osmotic equilibrium with the extracellular concentrations. The concentrations of Na, K, Cl and P both in the cytoplasm and in the regions of decondensed chromatin within the nuclei were found to be equal. However, in regions of condensed chromatin K⁺ concentrations were found to be much higher than expected for a Donnan distribution of ions free in solution. Most probably the activity coefficient for K⁺ is lower in the condensed chromatin than in the decondensed or in the cytoplasm. The same holds true for the A-band as compared to the I-band in heart muscle cells. A sequestration of K⁺ was measured also in the rough endoplasmic reticulum (RER) of hepatocytes. The Cl^? concentration in mitochondria both in heart muscle and liver cells has been measured far in excess of what might be expected from a Nernstian distribution. A coupled inward Cl^? transport in mitochondria must, therefore, be assumed.     

The compression and expansion waves of the forward and backward flows: an in-vitro arterial model

Although the propagation of arterial waves of forward flows has been studied before, that of backward flows has not been thoroughly investigated. The aim of this research is to investigate the propagation of the compression and expansion waves of backward flows in terms of wave speed and dissipation, in flexible tubes. The aim is also to compare the propagation of these waves with those of forward flows. A piston pump generated a flow waveform in the shape of approximately half-sinusoid, in flexible tubes (12 mm and 16 mm diameter). The pump produced flow in either the forward or the backward direction by moving the piston forward, in a 'pushing action' or backward, in a 'pulling action', using a graphite brushes d.c. motor. Pressure and flow were measured at intervals of 5 cm along each tube and wave speed was determined using the PU-loop method. The simultaneous measurements of diameter were also taken at the same position of the pressure and flow in the 16 mm tube. Wave intensity analysis was used to determine the magnitude of the pressure and velocity waveforms and wave intensity in the forward and backward directions. Under the same initial experimental conditions, wave speed was higher during the pulling action (backward flow) than during the pushing action (forward flow). The amplitudes of pressure and velocity in the pulling action were significantly higher than those in the pushing action. The tube diameter was approximately 20 per cent smaller in the pulling action than in the pushing action in the 16 mm tube. The compression and expansion waves resulting from the pushing and pulling actions dissipated exponentially along the travelling distance, and their dissipation was greater in the smaller than in the larger tubes. Local wave speed in flexible tubes is flow direction- and wave nature-dependent and is greater with expansion than with compression waves. Wave dissipation has an inverse relationship with the vessel diameter, and dissipation of the expansion wave of the pulling action was greater than that of the pushing action.     

高校学业考试作弊现象的社会学探析

从学生、学校、社会以及文化传统四个层面探微,认为高校学业考试作弊是学校场域中处于弱势地位的学生以追求分数为表象,以追逐位置和争夺资本为目的的主动“求生”策略,他们用异常的方式表达了对教育教学公平的渴望。而唯分数论的教育评价体系及僵化的考试形式对学生“超越”和偏离学校规章制度负有责任,反映了高校在教育理念、教学质量观、人才观、学生观等方面的迷失。当然,学历社会、考试社会中考试功能的畸变以及文化传统中重视考试的教育价值取向也隐含了高校教育逐渐由知识到标签的异化之路。对其防治乃是一个系统性的工程和长期性的过程。