空间曲柄滑块机构的运动分析

应用矢量回转法对空间曲柄滑块机构—RSSP机构进行了运动学分析,计算出滑块位移、速度、加速度函数。并基于Pro/E软件平台,对该RSSP机构进行了三维建模、运动仿真,得到滑块的位移、速度、加速度曲线,与理论计算进行对比,结果表明,两种方法所得结果完全一致。所得结论可为该机构在机床设计中的应用奠定理论基础。     

基于最大压力角α_(max)趋于最小的RSSP空间四杆机构优化设计

按已知的行程速比系数 k,滑块的最大行程 h,对 RSSP空间四杆机构进行优化设计 ,使该机构的最大压力角 αmax趋于最小 ,并给出了实例。     

可控机构的分类及应用

论述了可控机构是现代机构学的重要分支。对可控机构进行分类研究 ,以可控机构的输出柔性为特征将可控机构分为可调机构、变输入转速机构、混合驱动机构、电子凸轮机构等四大类。对每一类型的可控机构给出定义、应用研究现状分析、对较成熟的可控机构分支给出应用实例     

平面四杆轨迹机构近似综合的一种新方法

采用主、从支分别优化综合的数学模型进行轨迹机构近似综合，该方法可通过综合机构图形的适时显示，使设计者能直观地了解各种参数的不同选择对综合机构的影响。     

并联机构构型研究概述

并联机构是一种新型机构,具有传统串联机构无法比拟的优点,是串联机构的补充和扩展,对于机床技术和机器人技术的发展具有重要作用.本文介绍了并联机构的由来、特点和应用,并详细介绍了少自由度并联机构和解耦并联机构的构型发展,指出了并联机构需要解决的问题.     

议椭圆齿轮机构与摆动导杆机构之组合

本文在详细研究椭圆齿轮机构、摆动导杆机构以及两者组合机构的运动规律的基础上,提出一项合理组合椭圆齿轮机构与摆动导杆机构的有效方法。按该方法获得的组合机构与原摆动导杆机构相比较,它具有导杆端部的工作速度较均匀、导杆在工作行程的摆动时间较长以及在空回行程的摆动时间较短等优点。     

一种新型的间歇回转运动机构

在我们设计机床回转工作台时,常用到间歇回转运动机构。而较常用的是槽轮机构,但在实际使用中,槽轮机构尚存在某种不足之处。笔者设计了一种新型的间歇回转运动机构,经使用证明该机构运转性能稳定、可靠、构造简单,制造维修均很方便。     

一种新颖的间歇差动机构

笔者在设计“管道冷压合口安装机”时,设计了一套不完全齿轮间歇差动机构(以下简称“间歇差动机构”)。此机构是不完全齿轮间歇运动机构和齿轮差动机构的混合机构,结构简单紧凑,工作可靠。间歇差动机构的结构简图如图1所示。其结构主要由输入轴1、齿轮2、3、4,扇齿轮5及棘爪6所组成。其动作原理如下: 经减速后的旋转运动输入轴1,带动齿轮2和4低速旋转,齿轮2与大齿轮3常啮合,齿轮4与扇齿轮5间歇性啮合。扇齿轮5的轮廓空套在大齿轮3的内腔中,其接合面上设置棘爪机构6。当齿轮4与扇齿轮5啮合脱开后,由棘爪机构带动扇齿轮5随齿轮3同步旋转到下次啮合,当齿轮4与扇齿轮5啮合时,     

气动可调分度机构

在机械设备中,转位分度机构的设计通常采用棘轮机构、槽轮机构、凸轮机构和不完全齿的齿输机构等。这类机构的共同特点是：分度数单一,不可变;间隙时间固定,不可调,在实际使用中,主要对某种产品的加工进行分度。现介绍一种气动可调分度机构,其分度数在 24、 12、 8、 6、 4、 3、 2这 7种等分间任意可调,其间隙时间无级可调。该装置定位准确,自动化程度高,使用方便可靠。 [1]气动可调分度机构的结构 　　附图所示为气动可调分度机构简图。 　　该分度机构是由棘轮机构、齿轮齿条传动装置和气动元件组合而成的。其分度精度主要取决…     

凸轮组合机构在压力机上的应用

通过零件的工艺分析，设计了一套由凸轮组合机构组成的传动系统来控制模具的运动规律，结构紧凑简单。另外，该凸轮组合机构属于有动作时序要求的特殊并联组合机构，副凸轮机构属于机构的变异，为设计与选择凸轮机构在理论上提供了一种新思路。     

Partially compliant spatial slider-crank (RSSP) mechanism

In this study, a novel compliant mechanism, “partially compliant spatial slider-crank (RSSP)” is proposed. All possible configurations of compliant RSSP mechanisms are classified and discussed. A method is derived to determine deflection of the multiple-axis flexural hinge for all positions of the crank. A design procedure for partially compliant RSSP mechanisms is introduced. In order to prove the feasibility of the proposed mathematical model, a real model is built and it is shown that results are consistent.     

结合PRO/E和ADAMS进行RSSR空间机构运动分析

与平面机构相比,空间机构的分析设计比较困难,很难应用直观试凑法进行设计,几何作图法一般仅局限于解决比较简单的机构设计问题。本文介绍了空间机构运动分析的有限转动张量法,基于三维CAD软件建模。结合动力学分析软件进行了空间机构的运动分析。数值仿真结果表明,结合CAD/CAE软件进行空间机构运动分析的方法应用方便、易于推广,并可进一步为空间机构的动力学分析提供计算平台。     

考虑滑动副间隙空间机构的动力学研究

本文进行了含间隙滑动副（Ｐ副）空间机构的动力学研究。以ＲＳＳＰ机构为例,建立了机构的动力学方程并给出了数值解,计算结果表明,间隙对机构速度、加速度影响比较小,不象其它间隙运动副如圆柱副、回转副那样,对速度影响较小,而对加速度影响较大。     

空间并联机构位置分析的连续法

本文研究了四类由平台式机械手转化得到的空间并联机构的位置正解问题。当输入给定时，这些机构转化为ＲＲＲ—３Ｓ、ＲＲＰ—３Ｓ、ＲＰＰ—３Ｓ和ＰＰＰ—３Ｓ等四种空间多环结构共包括ＲＳＳＲ、ＲＳＳＰ、ＰＳＳＲ和ＰＳＳＰ等四种基本回路。对每个基本回路，用坐标变换矩阵法建立回路方程，进而得到上述四种空间结构的位置方程组，引入连续法，直接求出每种结构的全部位置解。数据实例表明，ＲＲＲ—３Ｓ结构与ＲＲＰ—３Ｓ结构各有１６组解，ＲＰＰ—３Ｓ结构有１２组解，ＰＰＰ—３Ｓ结构有８组解。     

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.     

Immunohistochemistry of neuronal nitric oxide synthase and protein nitration in the striatum of the aged rat

To ascertain the possible implications of the nitric oxide (NO*) producing system in striatal senescence, and by using immunohistochemistry and image-processing approaches, we describe the presence of the enzyme nitric oxide synthase (NOS), the NADPH-diaphorase (NADPH-d) histochemical marker, and nitrotyrosine-derived complexes (N-Tyr) in the striatum of adult and aged rats. The results showed neuronal NOS immunoreactive (nNOS-IR) aspiny medium-sized neurons and nervous fibres in both age groups, with no variation in the percentage of immunoreactive area but a significant decrease in the intensity and in the number of somata with age, which were not related to the observed increase with age of the striatal bundles of the white matter. In addition, NADPH-d activity was detected in neurons with morphology similar to that of the nNOS-IR cells; a decrease in the percentage of area per field and in the number of cells, but an increase in the intensity of staining for the NADPH-d histochemical marker, were detected with age. The number of neuronal NADPH-d somata was higher than for the nNOS-IR ones in both age groups. Moreover, N-Tyr-IR complexes were observed in cells (neurons and glia) and fibres, with a significant increase in the percentage of the area of immunoreaction, related to the increase of white matter, but a decrease in intensity for the aged group. On the other hand, we did not detect the inducible isoform (iNOS) either in adult or in aged rats. Taken together, these results support the contention that NADPH-d staining is not such an unambiguous marker for nNOS, and that increased protein nitration may participate in striatal aging.     

Immunolocalization of S100-like protein in the brain of an emerging model organism: Nothobranchius furzeri

The S100 protein in nervous tissue appears to play important roles in regulating neuronal differentiation, glial proliferation, plasticity, development, axonal growth, and in neurogenetic processes. In fish, the adult neurogenic activity is much higher than in mammals. In this study, the localization of S100 protein was investigated in the brain of annual teleost fish, Nothobranchius furzeri, which is an emerging model organism for aging research. By immunohistochemical techniques, S100 immunoreactivity (IR) was detected in glial cells, small neurons, and fibers throughout all regions of central nervous system (CNS) with different pattern of distribution. In the telencephalon, S100 IR was seen in the olfactory bulbs and in different areas of the telencephalic hemispheres. In the diencephalon, S100 positivity was observed in the habenular nuclei of the epithalamus, in the cortical thalamic nucleus, in the dorsal, ventral and caudal portions, the latter with the posterior recessus nucleus, and in the diffuse inferior lobe of the hypothalamus, along the diencephalic ventricle and in the dorsal optic tract. In the mesencephalon, S100 IR was observed in the longitudinal tori, in the optic tectum, and along the mesencephalic ventricle. In the rhombencephalon, S100 IR was shown in valvula and body of the cerebellum, and in some nuclei of the medulla oblongata. The results suggest that S100 may play a key role in the maintenance of the CNS and in neurogenesis processes in the adulthood.     

Changes in central steroid receptor expression, steroid synthesis, and dopaminergic activity related to the reproductive cycle of the ring dove

This review examines possible neural mechanisms involved in the expression of parental behavior in the ring dove, Streptopelia risoria. This avian species has proved an excellent animal model for studies concerning endocrine-behavior interactions for many years. Studies were performed to localize the expression of central androgen and progesterone receptor in both sexes. Expression of androgen receptor (androgen receptor immunoreactivity, AR-ir) was widespread but increased, similarly in both sexes, with increasing day-length. Progesterone receptor-immunoreactivity (PR-ir) was more localized in several discrete areas of the hypothalamus. Similarly, no sex differences were observed in PR-ir, and expression increased in birds maintained on long days. AR-ir demonstrated dramatic changes over the breeding cycle, being greatest in courting birds and almost undetectable in parenting birds of both sexes brooding their young. PR-ir showed a differential expression over the breeding cycle relative to its hypothalamic localization. PR-ir decreased in the tuberal hypothalamic area in brooding birds of both sexes; whereas in the preoptic area, PR-ir was maintained. Significant increases in dopaminergic activity during the parenting phase of the breeding cycle occurred in specific neural regions including the PVM and DMA. Studies demonstrated the ability of the diencephalon of both sexes of the ring dove brain to synthesize progesterone, with indications that in the male brooding dove, synthesis is increased. Finally, a model is presented that proposes a mechanism whereby these central systems may interact to result in the expression of full parental behavior in both sexes of the ring dove.     

Phase of acoustic impedance and performance of standing wave thermoacoustic coolers

Investigations on the relations between the phase angle of the acoustic impedance at the driver piston and the system performance of a standing wave thermoacoustic cooler were performed. The system performance measured at a fixed acoustic power showed that the coefficient of performance of the standing wave thermoacoustic cooler increases as the phase angle increases when the stack temperature span is relatively low. The results were consistent with the simulation results obtained from DELTAE, a computer code based on linear thermoacoustic theory. Analysis on the temperature profiles along the stack showed that the cooling efficiency (COP) of the system could be decreased or increased as the phase angle of the acoustic impedance at the driver piston changes depending on the stack temperature spans. This paper was recommended for publication in revised form by Associate Editor Yeon June Kang Insu Paek received the B.S. degree in Mechatronics Engineering from Kangwon National University, Chuncheon, Korea, in 1997, the M.S. degree in Mechanical Engineering from the University of Texas at Austin, USA, in 2000, and the Ph. D. degree in Mechanical Engineering from Purdue University, West Lafayette, USA, in 2005. He worked as a postdoctoral researcher in Purdue University and McGill University in 2006 and 2007. He is currently a faculty member in the Department of Mechatronics Engineering, Kangwon National University, Chuncheon, Korea. His research interests include thermoacoustic cooling and power generation, solar heat driven absorption cooling., and wind power. Luc Mongeau received the B.S. and M.S. degrees in mechanical engineering from the University of Montreal, QC, Canada, in 1984 and 1986, respectively, and the Ph. D. degree in Acoustics from Pennsylvania State University, University Park, USA, in 1990. He is currently a professor in the Department of Mechanical Engineering at McGill University, Montreal, QC, Canada. He has published over 50 archival journal publications on various topics related to acoustics and noise control. His research activities are in the flow and turbomachinery noise areas, as well as in the areas of voice production, and thermoacoustic refrigeration. James E. Braun received the B.S. degree in Mechanical Engineering from the University of Massachusetts, USA, in 1976, and the M.S. and Ph. D. degrees in Mechanical Engineering from the University of Wisconsin, Madison, USA, in 1980 and 1988, respectively. He is currently a professor in the Department of Mechanical Engineering, Purdue University, West Lafayette, USA. Professor Braun’s research combines the use of computer modeling, optimization, and experiments to study and improve the performance of thermal systems. He has published over 140 papers. Professor Braun is currently an associate editor for the international journal of HVAC&R Research. Shin You Kang received the B.S. and M.S. degrees in the Department of Mechanical Design from Seoul National University, Seoul, Korea, in 1982, and 1986, respectively. He then received the Ph.D. in Mechanical Engineering at the same university in 1992. Professor Kang is currently a professor in the Department of Mechatronics Engineering, Kangwon National University, Chuncheon, Korea. His research interests include mechanical structure design, crash analysis, optimal design, computational structure analysis and evaluation.