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1.
磁性液体倾角传感器的实验研究   总被引:2,自引:0,他引:2  
利用磁性液体二阶浮力原理设计出一种新型的一维倾角传感器,给出了传感器的电路结构方框图.实验研究了磁性液体倾角传感器的输出电压与倾斜角度、倾斜角度的正弦、激励信号峰值电压以及激励信号频率的关系.分析了由于永磁铁周围磁场的不均匀对磁性液体传感器稳定性的影响.  相似文献   

2.
涡激振动是诱发海洋管道与浮式平台系泊缆线等细长柔性圆柱结构疲劳损伤的重要因素,已有研究大多关注结构轴向与来流垂直的情况,实际的海洋工程中,圆柱结构轴向与来流并不完全垂直,存在一定倾斜角度。针对这种复杂的情况,倾斜圆柱涡激振动的不相关原则被提出,即假定倾斜圆柱涡激振动与来流速度在结构轴向的垂直方向投影分量引起的垂直圆柱情况等价。然而,较大倾角条件下不相关原则的正确与否仍未知。为了论证大倾角倾斜柔性圆柱涡激振动不相关原则,开展了长径比为350,倾角为45°的倾斜柔性圆柱涡激振动实验,采用应变传感器测量结构应变信息,运用模态分析法对实验数据进行处理。通过大倾角倾斜圆柱与垂直圆柱的实验结果对比,发现在控制模态转化区域,倾斜圆柱更容易被激发高阶模态,同时倾斜圆柱与垂直圆柱在测点处的应变和位移差异较大,并均出现高频特征。最终得出了较大倾角状态下倾斜柔性圆柱涡激振动不相关原则不成立的结论。  相似文献   

3.
提出了一种基于等截面梁弯曲变形原理的灵敏度可调型光纤布拉格光栅(FBG)倾角传感器,通过FBG光栅感受因结构倾角改变而引起的等截面梁弯曲变形,进而实现对结构倾斜角度的测量,并构建了灵敏度可调型光纤FBG光栅倾角检测系统.实验结果表明,该FBG倾角传感器测量范围为±35°,最高灵敏度达到56.93pm/(°),测量精度为0.02°.该传感器可通过改变等截面梁的宽度还可实现对倾角检测灵敏度的有效调节.  相似文献   

4.
矢量线阵二维波达方位估计的方法   总被引:2,自引:1,他引:1       下载免费PDF全文
赵微  李秀坤 《声学技术》2008,27(5):658-661
声矢量传感器南声压传感器和质点振速传感器组成,它可以空间共点、时间同步测量声场的声压标量和振速矢量信息。钏对声压线阵无法同时分辨目标的方位角和俯仰角,而三维矢量传感器线阵会带来成本的增加和工程应用上的困难.利用二维矢量传感器组成的直线阵对目标的二维波达方位进行联合估计,详细推导了矢量阵MUSIC算法的数学表达式,并着重对矢量线阵在三维坐标不同轴上时对方位估计的影响进行了研究。仿真结果表明二维矢量线阵布放在水平的X轴或Y轴上时存在方位模糊.而布放在垂直的Z轴上时可以实现全空间无模糊定向,且对双目标也有较高的分辨率。  相似文献   

5.
赵梅  胡长青 《声学技术》2010,29(4):365-369
针对浅海倾斜海底海洋环境,对声场的空间相关性进行了研究。利用抛物方程法,对浅海声场的空间相关系数进行数值模拟,并结合2001年东中国海中美联合实验数据,分析了声场空间相关系数与海底倾斜角度、接收阵元与参考阵元的间隔、参考阵元深度及声源深度之间的关系。对于上坡海底,浅海声场空间相关性随着海底倾斜角度、接收阵元与参考阵元间隔的变大而变弱,且垂直相关系数随着接收阵元与参考阵元间隔的增大,先衰减再出现起伏。  相似文献   

6.
为了使测量设备快速进入测量状态,减小因倾斜带来的测量误差,结合工程实际应用,根据光学成像理论,利用水平倾角仪测量的角度值,建立了一个实时调平补偿的数学模型.根据不同的测量设备确定其补偿算法,可对测量设备在一定的倾角范围内倾斜时进行实时补偿,并进行了实验验证.实验结果表明,测量设备在倾角α=0.325°,β=0.896°倾斜情况下,经过实时补偿可将系统测量误差由0.126%提高到0.026%.  相似文献   

7.
探讨了将倾角信息引入基于力信息的签名识别是否能有效消除传统数字书写笔在书写过程中须保持固定姿态的这种限制,是否会对系统的识别性能产生影响.采用书写力传递的方法,将倾角信息与力传感器的信息相结合,实现了多传感器信息融合,并将含有倾角信息的书写力与无倾角信息的书写力进行了识别性能对比试验.结果表明,在固定握笔姿态下,倾角信息对识别率的影响不大,而在自由握笔姿态下,倾角传感器与力传感器相结合可以有效提高系统识别性能.  相似文献   

8.
垂直水听器线列阵接收的声数据或其互谱密度矩阵可以用来提取浅海波导声传播的简正波模深度函数、水平波数和海底参数。在实际应用中,布放在海洋中的垂直水听器线列阵不可避免地产生倾斜。计算机仿真结果表明,垂直阵的倾斜使提取参数误差大幅增大。针对此问题,提出模值追踪法,构建模值追踪代价函数,对垂直水听器线列阵声数据互谱密度矩阵的本征矢量的模值进行逼近。仿真结果表明,模值追踪法可以有效消除基阵倾斜的影响。在仿真条件下,水平波数估计误差小于0.1%,海底相移估计误差在±1.1范围内。  相似文献   

9.
专门讨论了基元振幅不一致性对圆柱阵指向性特性的影响。圆柱阵母线上基元的不一致性对圆柱阵水平指向性毫无影响;圆柱阵垂直指向性主要取决于母线的指向性,因而能用线阵的布阵设计来预估圆柱阵垂直指向性特性。  相似文献   

10.
成形具有一定曲率的夹层结构时,需要将蜂窝芯铣削成曲面形状,造成蜂窝胞壁呈一定倾角,进而降低蜂窝夹芯结构面外承载能力。为了定量化分析面外载荷作用下倾斜胞壁蜂窝芯的力学性能,建立了倾斜胞壁蜂窝芯面外压剪复合有限元模型,并通过设计专用Arcan夹具实现蜂窝芯的面外压剪复合加载,用于验证模型的有效性。对比仿真与实验结果,发现蜂窝芯压剪响应及胞壁变形模式吻合较好。利用验证的有限元模型对胞壁倾角范围为0°~40°的蜂窝芯在面外压剪复合载荷下的力学响应进行了研究,结果表明随着蜂窝胞壁倾角的增大,蜂窝芯面外承载能力逐渐降低;当胞壁倾斜角由0°增加到40°,初始应力峰值下降最大幅度为47.7%,平原阶段强度下降幅度为29%;进一步分析了倾斜胞壁蜂窝芯截面芯格尺寸与胞壁倾角的几何关系,将倾斜胞壁蜂窝芯等效为具有相同截面尺寸的垂直胞壁蜂窝芯,推导了倾斜胞壁蜂窝芯在面外压缩及剪切载荷作用下的坍塌强度,揭示了胞壁倾角对蜂窝芯坍塌强度影响机制。  相似文献   

11.
基于时延估计的海底线阵阵形估计方法研究   总被引:3,自引:0,他引:3       下载免费PDF全文
牛嗣亮  倪明  廖毅  梁迅 《声学技术》2007,26(2):296-300
阵形估计是水听器阵列应用中的关键问题,基于时延估计的阵形估计方法比基于传感器测量和基于匹配场处理的方法具有更强的适应性和较高的精度。针对浅海水听器阵列中水平长线阵存在的纵向相关振荡现象引起的不能简单以某一阵元为基准求相对时延的问题,充分利用了阵元信号的高相关性,提出了基于子阵时延的阵形估计方法,针对子阵间时延估计误差向阵端累积的问题,该方法以时延估计的克拉美罗界为依据提出了合理的子阵方式,在一定程度上减小了误差传递。对已有海试数据阵形估计处理的结果表明,相对于单源固定间距方法和未分子阵的双源时延估计方法,基于子阵时延的阵形估计方法满足阵元间距的约束,有较好的空间谱特性,减小了阵形估计误差,对长水听器阵列的应用及阵形估计具有较大应用价值。  相似文献   

12.
A method for obtaining the tilt angle and direction in a two-dimensional plane, by using a photoelectric inclination sensor consisting of an LED, a hemispherical spirit level, and a photodiode array is explained. An application of the sensor to the measurement of the shape of a 3-D object is also described. Light from the LED projects a bubble in the spirit level and throws a shadow onto the surface of an array composed of four equivalent p-n junction diodes, isolated from each other by a cross on a wafer. The tilt angle and direction in a two-dimensional plane are obtained by combining the diode outputs. By positioning the sensor on the crosspoints of the lines drawn longitudinally and latitudinally at an interval on the surface of a small mountain in a Japanese garden, the x and y components of the tilt angle can be obtained and its shape is reconstructed by a computer. The principle of the sensor, the system to display the tilt angle and its x and y components, and the application of the system to the measurement of the shape of a mountain are explained  相似文献   

13.
提出利用PVDF阵列直接测量结构曲率模态。在振动梁表面均匀布置一组PVDF压电薄膜,测量结构在外加点激励作用下的动态响应,得到频率响应函数,进而通过模态软件对数据进行分析,得到其曲率模态。数值分析和实验结果表明:利用PVDF阵列可以有效地测量得到结构的曲率模态,且方法与激励力位置无关。由于方法操作简便,PVDF压电薄膜附加质量可忽略不计,与常规通过模态振型计算曲率模态的方法相比具有明显优越性。  相似文献   

14.
林晋美  涂英  蔡惠智 《声学技术》2007,26(3):399-405
本文介绍了两种用于校正大型柔性声纳阵列的阵元位置的方法。在阵列进行海底铺设后,阵元位置的不确定,会大大降低声纳搜索方位的性能。辅助阵元校正方法考虑使用阵上较短距离间隔的阵元作为辅助阵元来对信号到达角和阵元相对相位同时进行估计。并从至少两组不同方位声源点测得的数据,获得阵元的相对坐标位置,得到阵形。为了保证校正的有效性,我们比较了这两种辅助阵元校正方法,通过大量的仿真试验比较它们对辅助阵元误差扰动的敏感度,并选择了宽容性较好的MUSIC辅助阵元方法进行了实际的海上试验。  相似文献   

15.
Measurements of thermal magnetization fluctuation noise spectrum in multi-directional magnetic field reveal tilt of effective free layer orientation in TMR sensors. We propose a method for effective sensor stiffness field measurement and demonstrate that deviations of stiffness from nominal values are caused by the angular dependence of the stiffness field. Ferro-magnetic resonance peak measurements indicate that the free layer magnetization orientation may be tilted from the cross-track direction. This magnetization tilt is caused by reference layer, hard bias problems and shape anisotropy effects. This reduces sensor efficiency and leads to amplitude asymmetry, multi-domain configuration and sensor instability. FMR-based method for detection of potentially unstable heads based on these observations is proposed.  相似文献   

16.
We report here the development of a new vapor sensing device that is designed as an array of optically based chemosensors providing input to a pattern recognition system incorporating artificial neural networks. Distributed sensors providing inputs to an integrative circuit is a principle derived from studies of the vertebrate olfactory system. In the present device, primary chemosensing input is provided by an array of fiber-optic sensors. The individual fiber sensors, which are broadly yet differentially responsive, were constructed by immobilizing molecules of the fluorescent indicator dye Nile Red in polymer matrices of varying polarity, hydrophobicity, pore size, elasticity, and swelling tendency, creating unique sensing regions that interact differently with vapor molecules. The fluorescent signals obtained from each fiber sensor in response to 2-s applications of different analyte vapors have unique temporal characteristics. Using signals from the fiber array as inputs, artificial neural networks were trained to identify both single analytes and binary mixtures, as well as relative concentrations. Networks trained with integrated response data from the array or with temporal data from a single fiber made numerous errors in analyte identification across concentrations. However, when trained with temporal information from the fiber array, networks using "name" or "characteristic" output codes performed well in identifying test analytes.  相似文献   

17.
Peng G  Trock E  Haick H 《Nano letters》2008,8(11):3631-3635
An array of chemiresistive random network of single-walled carbon nanotubes coated with nonpolymeric organic materials shows a high potential for diagnosis of lung cancer via breath samples. The sensors array shows excellent discrimination between the volatile organic compounds (VOCs) found in the breath of patients with lung cancer, relative to healthy controls, especially if the sensors array is preceded with either water extractor and/or preconcentrator of VOCs. The pattern compositions of the healthy and cancerous states were determined by gas-chromatography linked with mass-spectroscopy (GC-MS) analysis of real exhaled breath.  相似文献   

18.
A novel six-degrees-of-freedom (six-DOFs) alignment technique for assembling two-dimensional array components is presented. The technique uses off-axis linear Fresnel zone plates on one component that are combined with alignment targets on the other. The technique is compact and sensitive to all six DOFs; it was used to package an array of microlenses with a 32 x 32 array of GaAs multiple-quantum-well modulators flip-chip bonded to a 9 mm x 9 mm complementary-metal-oxide-semiconductor chip. By use of interference fringes to control the tilt misalignment, the worst-case misalignment of the microlenses relative to the chip is calculated to be as follows: lateral = 3.0 mum, rotational = 0.023 degrees , longitudinal = 13 mum, and tilt = 0.022 degrees . We also propose alternative implementations of the technique, including one that uses on-chip photodetectors to automate this six-DOF alignment technique.  相似文献   

19.
We are developing a method to build arrays of Ge-based microcalorimeters for soft X-rays detection using micro-photolithographic techniques. A key element of the process is the electrical and thermal connection between the germanium sensors and the interconnection electrical tracks, that lay on a substrate acting as mechanical support and thermal sink. The geometry of the sensors, that have a square base truncated pyramid shape, makes feasible a connection through indium soldering. We describe a technique, based on microlithography and electroplating, adopted to grow indium bumps of a few tens of square microns of area and several microns high on top of the contact pads patterned on the substrate. The sensor array is placed over the bumps and a subsequent baking melts the indium, soldering the sensors to the pads.  相似文献   

20.
Capacitive sensor arrays in dimensional analysis of surfaces   总被引:1,自引:0,他引:1  
The theoretical aspects of dimensional analysis and shape reconstruction of surfaces by means of displacement sensor arrays are investigated. Although this analysis is focused on surface profiles and linear arrays of capacitive sensors, its results could be easily extended to surfaces and bidimensional arrays of displacement sensors. Capacitance variations related to sensor-to-surface displacements during array scanning are used in the reconstruction equations obtained from the analysis. The reconstruction accuracy depends mainly on the dimensional stability of the array, and it is independent from the array trajectory. The problems raised by nonideal array and sensor behavior, such as fringe effects and geometry deviations are discussed. Capacitance variations due to such effects are calculated and taken into account by means of an energy method. A reconstruction system based on the theoretical results is proposed, and its performance in the reconstruction process is evaluated by a computer simulation which accounts for measurement uncertainties. Simulation results confirm both the effectiveness of the method and the feasibility of the system. Its features are compared with those of other noncontact surface-measuring instruments, and possible applications are outlined  相似文献   

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