一种电容式角度传感器

为了研制一种线性较好的角度传感器,利用变介电常数原理设计了角度传感器.发生角度变化时,借助气体和液体在两个电极间深度或高度的变化,引起两电极间电介质的介电常数和电量变化,从而导致相应电容发生变化.经过试验验证,传感器的非线性可以达到0.02%～0.05%.利用这种原理设计的角度传感器具有较高的非线性、重复性和分辨率.     

非接触式电子油门踏板角度传感器结构的创新设计

本文对一种非接触式电子油门踏板角度传感器的结构进行了创新设计研究,将这种传感器的结构与电子油门踏板机械结构相比较,非接触式电子油门踏板角度传感器不仅具有较高的输出精度,而且这种脚踏板的尺寸小、具有较高的灵活性、通用性强等特点。将非接触式电子油门踏板角度传感器的结构进行创新设计,可以有效地解决角度传感器装配存在误差大的问题,同时也能够使得其输出精度大幅度提高,并在一定程度上对分体式角度传感器的体积过大问题进行初步解决。     

基于磁旋转编码器的角度传感器动态误差补偿方法

设计了一种基于磁旋转编码器的角度传感器,分析了该角度传感器产生动态误差的原因,提出了可减小动态误差方法。该方法能有效地补偿动态误差,使角度传感器在转速高、转速变化快的动态测量中测量误差小于0.1°。     

基于磁敏测量技术的拉线式位移传感器

基于磁敏感角度测量处理器MLX90316开发了一种拉线式位移传感器。分析了拉线位移传感器的测量原理并推导了拉线位移与滚轮角度的解析关系。基于Cortex ARM处理器,设计了位移传感器的角度信号采集和信号输出电路;完成了传感器的整机机械结构设计。开发了位移传感器的应用软件,具有参数设置、传感器标定及符合标准Modbus协议的通讯等功能。试验表明:拉线式位移传感器测量精度能达到0.02 mm,性能稳定,可满足工业领域对位移测量的需求。     

新型低温漂电容式角度传感器的研究

针对常用的电容式角度传感器温漂较大问题,设计了一种新型低温漂电容式角度传感器及测量电路。传感器主要包括前极板、转轴、陶瓷介质和后极板,其中前、后极板采用碳氢化合物材料制作,前极板通过陶瓷介质和后极板构成差动式平板电容器。电容传感器的后极板设置激磁电路产生传感器用高频激磁信号,前极板设置电容差分调幅电路将与输入角度对应的容值转换成电压值输出。文中设计的新型电容式角度传感器,可通过提高激磁信号频率来提升传感器的灵敏度,且利用外部自动增益控制电路,保证了传感器在温度变化时其灵敏度基本不变。     

操纵杆角位移测量装置的设计

为克服操纵杆接触式角度传感器带来的机械磨损从而影响输出特性的缺陷,采用TDK-Micronas公司最新款的磁传感器编程器TDK MSP V1.0为软件开发平台,以HAL 3725霍尔芯片设计出一种非接触式角度霍尔传感器.通过对传感器芯片的选型,传感器模型与标定实验平台的搭建,硬件电路的设计以及编程器对传感器标定的软件流...     

电感式角度传感器电磁耦合敏感元件的研究

针对传统角度传感器结构复杂、制造成本高,且不易于嵌入式安装等不足,设计研究了一种基于PCB板的平面电感式角度传感器上的电磁耦合敏感元件。分析了此电感式角度传感器的实现机理,根据实现机理,建立了理论模型;在ANSYS Maxwell软件中创建了激励线圈、接收线圈和转子的实体模型,并进行了电磁耦合仿真分析,仿真结果验证了设计的合理性与可行性。根据理论模型制作原型敏感元件,在角度传感器实验台上进行电磁耦合实验,得到转子转动角度与接收信号峰峰值变化的对应关系,分析其影响因素。改进设计,对改进型敏感元件进行电磁耦合实验,实验结果表明改进型敏感元件提高了角度检测的灵敏度,3组接收信号峰峰值变化曲线中间部分线性度良好,且能完整覆盖一个变化周期。     

车辆角度传感器安装机构的设计

为了解决车辆狭窄空间处安装角度传感器不方便的问题,专门设计了角度传感器安装机构,该机构包括连杆支撑件、连杆、摇杆和角度传感器。该安装机构通过Z字形连杆支撑件,将转向拉杆与转臂之间的连接点升高,使其与角度传感器处于同一平面,并将转臂绕车架转动角度的测量转化为对摇杆绕角度传感器测量轴转动角度的测量,从而实现车轮转向角度实时测量。该安装机构具有操作简便、省力、方便拆装以及适用于狭小空间等优点。     

磁敏角度传感器特性分析

设计了一种基于磁阻效应(AMR)和霍尔效应的角度传感器。论述了传感器的工作原理、电路组成及功能。传感器由磁阻芯片、霍尔芯片、放大以及滤波电路构成。通过旋转圆柱永磁体改变磁阻芯片、霍尔芯片周围磁场,引起传感器输出电压变化,进而测量旋转角度。在传感器结构设计中,对圆柱永磁体进行了磁场有限元分析,对角度传感器进行了试验标定与数据分析。测试结果表明:在0°~360°范围内,重复性误差为0.58%,迟滞误差为0.33%,综合误差为1.82%,达到了实际角度测量的要求。     

高精度随钻定向测量仪的设计

以3轴加速度传感器和3轴磁通门传感器为基础,设计了定向传感器的角度测量模型;通过对传感器温度误差和安装误差的分析,研究了影响传感器精度的因素,提出了能有效提高传感器测量精度的误差校正模型.以微控制器MSP430F149和模数转换器ADS1216为核心,设计了硬件滤波电路和信号采样电路;基于角度测量模型和误差校正模型,给出了姿态参数采集的主程序和误差补偿程序流程图.实验分析表明:在高温高压强振的环境下该系统达到了所提出的精度指标.     

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.     

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.     

A synchrotron X-ray study of the changes occurring in the corneal stroma during processing for electron microscopy

Using a high-intensity synchrotron X-ray source, the structural changes occurring in the corneal stroma were monitored during each stage of several different processing runs for the transmission electron microscope (TEM) and scanning electron microscope (SEM). The parameters studied were interfibrillar spacing, intermolecular spacing, D-periodicity and fibril diameter. The processing schedule that produced the least changes in spacings for TEM specimens involved extended fixation in glutaraldehyde followed by low-temperature embedding in Lowicryl K4M resin. However, interfibrillar material was better preserved after embedding in LR White resin or Nanoplast. Almost every processing stage for electron microscopy produced significant changes in one or more structural parameters in the cornea. Glutaraldehyde fixation significantly increased the intermolecular spacings, while resin infiltration and resin polymerization each resulted in shrinkage of all the spacings monitored. Critical-point drying for SEM specimens resulted in considerable shrinkage in all three spacings, but was still preferable to air drying, which caused reduction in the order of the fibril packing, resulting in loss of the interfibrillar X-ray pattern. Perhaps the most drastic effect was caused by post-fixation in osmium tetroxide, which resulted in loss of the intermolecular pattern, and also increased the amount of shrinkage in the interfibrillar spacings and the D-periodicity which occurred during later stages of processing.     

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.     

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.     

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.     

Anisotropic properties of bovine nasal cartilage

To investigate the structural anisotropy in bovine septal cartilage, quantitative procedures in microscopic magnetic resonance imaging (μMRI), polarized light microscopy (PLM), and mechanical indentation were used to measure the tissue in three orthogonal planes: vertical, medial, and caudocephalic. The quantitative T2 imaging experiments in μMRI found strong anisotropy in the images of both vertical and caudocephalic planes but little anisotropy in the images from the medial plane. The PLM birefringent experiments found that the retardation values in the medial section were only about 10% of these in the vertical and caudocephalic sections and that the angle values in all three sections followed the rotation of the tissue section in the microscope stage. The stress relaxation experiments in mechanical indentation showed reduced stiffness in the medial plane compared to stiffness in either the vertical or caudocephalic planes. Collectively, the results in this project coherently indicate a marked structural anisotropy in cartilage from the nasal septum, where the long axis of the collagen fibrils is oriented in parallel with the medial axis.     

基于Windows9X的数控系统实时控制研究

文章通过研究Windows9x系统的定时器与系统实时钟及硬中断机制，给出院实现实时控制的解决方案；通过硬中断的处理实现位置控制，通过软件方法实现及其它实时功能。