白马铁矿及及坪4~#矿石破碎站位置优化研究

本文从自卸汽车和胶带联合运营成本方面进行分析,研究及及坪4~#矿石破碎站位置优化的必要性及破碎站布置确定方法,并结合及及坪矿山地质条件、工程建设投资,提出及及坪4~#矿石破碎站的合理位置。     

自动控制设备可靠运行与研究

自动控制设备及信号系统在运行中,由于环境及电路布线等原因产生各类电干扰,严重影响了系统及设备运行的可靠性及稳定性。本文对此类干扰源的产生及处理方法加以论述。     

燃气轮机与汽轮机应用于机车牵引动力的可行性分析研究

本文介绍了燃气轮机及汽轮机两种机组之间的差异及当前的铁路运输状况,并重点分析了燃气轮机及汽轮机应用于当前铁路牵引的优势及劣势,并分别与内燃机及蒸汽机进行对比,作出了可行性分析,为相关研究及工程应用提供了必要的理论依据。     

采用IC传感器的露点测量

在比较露点测量方式及传感器的基础上,讨论了使用相对湿度传感器检测及转换成露点的方法,提供了参数间的关系及适于工程应用的理论依据,并结合集成湿度传感器及测量实例介绍了它们的特性及使用方法,指出使用条件的影响因素及补偿途径,并提供了检测软件计算的流程及具体表达式,以及检测软件的其它实现方式。     

冷焊及化学密封技术在设备修理中的应用

介绍了"冷焊"及密封锁固技术较传统热焊接、热喷漆、电镀及密封锁固技术以及圆柱固持技术的不同、基本工作原理及技术特点。详细介绍了固化反应过程及反应过程中温度控制点和控制时限。列举了典型零件的"冷焊"工艺及方法、平面密封技术和圆柱固持技术的工艺、方法及注意事项。还介绍了"冷焊"及密封锁固技术的安全要求及应用范围。     

斜柱塞轴向柱塞泵的运动学及动力学特性

详细分析了斜柱塞的运动学及动力学特性,并通过建立斜柱塞及直柱塞SIMULINK仿真模型,比较分析了斜柱塞及直柱塞的运动学及动力学特性,同时列出了斜柱塞给柱塞泵带来的好处及坏处。     

基于ADAMS的100t汽车起重机转向系统的优化

针对100 t汽车起重机转向系统存在跑偏及磨胎的问题,通过理论分析及ADAMS仿真对转角进行优化,确定各铰接点坐标,优化拉杆布置;采用Ansys Workbench对拉杆及中间摇臂作应力及屈曲计算,优化了拉杆及摇臂材料及工艺,降低了成本。     

机电信息

当前国家重点鼓励发展的产业、产品和技术目标(机电部分 )(二 )　　38、智能式低压电器制造　　39、高强度异型紧固件制造　　40、 20t/h及以上树脂砂铸造设备制造　　41、先进模具设计、制造技术开发及设备制造　　42、大型真空电子束焊技术开发及设备制造　　43、可控气氛及真空热处理技术开发及设备制造　　44、安全生产及环保检测仪器新技术设备制造　　45、秸杆分解利用新技术及关键设备制造　　46、城市垃圾处理技术开发及设备制造　　47、大型污水处理技术开发及设备制造　　48、烟气脱硫脱硝设备制造　　49、重大自然灾害监测技术及…     

汽车电动天窗布置及校核方法的研究

简单介绍了汽车天窗的形式及特点;运用图片及断面示意,阐述了天窗布置的原则及方法;以在研车型为例,介绍了天窗的校核方法及要点;得出一套天窗布置及校核的方法。     

适于往复机械非平稳振声分析及诊断技术的研究及应用

针对往复机械非平稳时变冲击型振声特点,提出了同步锁相滤波预处理、AR-短时谱（STP）及AR-伪Wigner分布（PWVD）等适用的处理及分析方法。以190柴油机诊断为具体应用目标,进行了以上理论及方法的验证及应用工作。试验及分析结果表明了以上方法的有效性及工程实用性。对于几种机器故障状态的分析结果,以上各方法间的对应情况相当好,符合机器运行机理及故障特征,是进行往复机械振声分析及诊断的有效途径。     

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.     

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.     

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.     

Mechanotransduction-The relationship between gravity,cells and tensile loading in extracellular matrix

Gravity plays a central role in vertebrate development and evolution. Mechanotransduction involves the tensile tethering of veins and arteries, connections between the epidermis and dermis in skin, tensile stress concentrations that occur at tissue interfaces, cell-cell interactions, cell-collagen fiber stress transfer in extracellular matrix and fluid shear flow. While attention in the past has been directed at understanding the myriad of biochemical players associated with mechanotransduction pathways, less attention has been focused on determining the tensile mechanical behavior of tissues in vivo. Fibroblasts sit on the surface of collagen fibers in living skin and exert a retractile force on the fibers. This retractile force pulls against the tension in collagen fibers in skin. After fibroblast-collagen fiber interactions are altered either by changes in fibroblast adhesion or after formation of cancer associated fibroblasts, and changes in cell junctions, alterations in the retractive force leads to changes in mechanotransduction. The purpose of this paper is to present a model of tensile forces that occur at the fibroblast-collagen fiber interface and how these forces are important in extracellular matrix physiology in health and disease.     

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.     

Effects of humidity on nanometer scale wear of a carbon film

Influence of environmental humidity on scanning-scratched wear tests of a carbon film deposited by electron cyclotron resonance plasma sputtering are evaluated in both air and nitrogen with an atomic force microscope and a diamond tip. Wear depth is larger in higher humidity and also larger in air than in nitrogen. Effect of humidity on scratch load dependence and repeated scanning-scratch tests are larger in nitrogen than in air. Effect of humidity on wear is clearer in the repeated scanning-scratch test than in the scratch load dependence test especially in air, and also clearer at larger scratch load. In scratch velocity dependence test, there is a tendency that wear depth decreases with increase in logarithm of scratch velocity both in air and nitrogen. Wear models to explain the experimental results are discussed.     

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.     

Analysis of weld-induced residual stresses and distortions in thin-walled cylinders

Circumferential weld specifically in thin-walled structures is a common joint type in the fabrication of structural members in aerospace, aeronautical and pressure vessel industries. This type of weld joint suffers various types of weld-induced residual stress fields (hoop and axial) and deformation patterns (axial shrinkage, radial shrinkage). These imperfections have negative effects on fabrication accuracies and result in low strength welded structures that can lead to premature failures. To precisely capture the distortions and residual stresses, computational methodology based on three-dimensional finite element model for the simulation of gas tungsten arc welding in thin-walled cylinders is presented. Butt-weld geometry with single “V” for a 300 mm outer diameter cylinder of 3 mm thick is used. The complex phenomenon of arc welding is numerically solved by sequentially coupled transient, non-linear thermo-mechanical analysis. The accuracy of both the thermal and structural models is validated through experiments for temperature distribution, residual stresses and distortion. The simulated result shows close correlation with the experimental measurements. This paper was recommended for publication in revised form by Associate Editor Dae-Eun Kim Naeem Ullah Dar received the B.Sc. and M.S. degrees in mechanical engineering from the Univer-sity of Engineering & Technology, Taxila, in 1989 and 2004 respectively. Presently, he is PhD scholar in mechanical engineering at UET, Taxila. His publications are over 25 in different Int. journals and conferences. His research includes manufacturing process (GTAW welding process, HSM process, abrasive waterjet process, incremental forming etc), welding simulations, optimization, and expert system. He spent more than 16 years in different mechanical manufacturing fields. He also received MBA degree in project management and six sigma black belt from SQII in 2005. Ejaz M. Qureshi is currently a graduate student working for his PhD in computational weld mechanics at National University of Sciences and Technology (Pakistan). After receiving his B.S. degree in Mechanical Engineering in 1997, he worked for five years in an industrial manufacturing setup producing hi-tech welded structures. Qureshi has published numerous technical papers in professional refereed journals and conferences of international repute. He has also been an active referee for several conferences and journals. His current research interests include: manufacturing processes simulation, structural integrity of welded structures and computational plasticity of cylinders/pressure vessels. M.M.I. Hammouda received the B.Sc. and M.Sc. degrees in mechanical engineering from Al Azhar University, Cairo, Egypt in 1970 and 1975 respectively. He received his PhD degree in mechanical engineering from Cambridge University, England in 1978. His has more than 35 publications in different International journals and conferences. The research includes mechanical behavior of engineering materials, linear elastic and elastic-plastic fracture mechanics, manufacturing process modeling and simulations. Presently being a foreign faculty professor in mechanical engineering department of UET, Taxila, Pakistan, he spent more than 25 years in academic and teaching. He is a member of the Editorial Board of the International Journal of Fatigue and Fracture of Engineering Materials and Structures. [www.blackwell-science.com].     

Ciliary neurotrophic factor increases the survival of magnocellular vasopressin and oxytocin neurons in rat supraoptic nucleus in organotypic cultures.

Organotypic cultures of the rat hypothalamus are very useful models for the long-term study of parvocellular vasopressin (VP) neurons in the paraventricular (PVN) and suprachiasmatic (SCN) nuclei. However, they do not preserve significant numbers of VP magnocellular neurons (VP-MCNs) in either the PVN or the supraoptic nucleus (SON). Vutskits et al. [(1998) Neuroscience 87:571-582] reported that ciliary neurotrophic factor (CNTF) was a selective survival factor for rat VP-MCNs in organotypic cultures of the rat hypothalamic paraventricular nucleus (PVN). We examined the effects of CNTF on the survival of these neurons in rat and mouse SONs. CNTF (10 ng/ml) in the culture media increased the survival of VP-MCNs by 6-fold and OT-MCNs by 3-fold. In the mouse, both OT- and VP-MCNs survive very well in organotypic cultures under standard culture conditions and the addition of CNTF had no further effect. Consistent with these results, in situ hybridization showed substantially higher levels of VP- and OT-mRNA in rat PVNs and SONs in the presence of CNTF, but produced no changes in these nuclei in the mouse. The optimum period for the survival effect of CNTF on MCNs in the rat hypothalamic cultures was in the first 7-10 days of culture and this effect is maintained for at least 5 additional days if CNTF is then removed from the medium. Therefore, using CNTF in the culture media can provide an opportunity for long-term studies of rat VP- and OT-MCNs in SONs in organotypic cultures.