基于目标特征尺寸的可视化被动测距系统

为克服传统光电被动测距系统稳定性差、远距离条件下测距精度收敛性差、系统难以小型化等不足,本文提出一种基于目标特征尺寸的可视化光电被动测距系统。建立了被动测距模型并分析测距原理,从理论上分析获得距离反演公式和测距误差精度;设计了被动测距算法并分析相关成像参数获取途径和方法;通过高清成像器、半导体激光器和信号处理器等软硬件设计,实现了系统的可视化被动测距功能和全天候图像信息获取;最后通过目标特征尺寸及其成像系统参数反演目标距离,实现了在成像过程中实时测距并进行被动测距实验验证。实验结果表明,被动测距精度优于10%,当前软硬件参数配置下,目标的测距距离大于1km,测距鲁棒性好,性能稳定,可广泛应用于全天候目标图像信息获取和光电被动测距的实际工程实践中。     

单矢量水听器被动测距方法研究

提出一种利用单矢量水听器接收信号的相位信息实现目标被动测距的方法。该方法借鉴匹配场被动定位的思想,首先根据简正波声场模型建立匹配模板,然后引入图像处理中的相位相关算法,将目标的相位信息与模板进行匹配,从而得到目标的距离。对该方法的有效性与稳健性进行了详细地研究与分析。仿真结果表明,该方法可以有效地实现目标的被动测距,且具有稳健性强、计算速度快、不需要考虑阵型姿态失配等优点,是声呐信号处理的新途径,为实际的工程应用奠定了理论基础。     

相关K分布法在氧气吸收被动测距中的应用

为快速、准确地解算氧气吸收被动测距技术中氧气吸收率所对应的路径长度,对该项技术中氧气吸收率与路径长度的数学模型进行了研究。首先证明了不同温度压强下氧气吸收系数分布的强相关性,给出了吸收系数分布随温度和压强的变化规律;其次利用相关K分布法和曲面地球模型建立了实际非均匀路径上氧气吸收率与路径长度的数学模型;最后对提出的模型进行了理论分析与实验验证。结果显示:本文数学模型不仅能够很好地适应不同大气模式的变化,而且能够快速、准确地计算出指定路径上的氧气吸收率曲线和目标距离;平均数学模型下的相对测距误差为4.4%,消除背景减小测量误差后数学模型解算距离的相对误差仅为1%。结论表明:利用相关K分布法建立的数学模型能够很好地解决氧气吸收被动测距技术中的距离反演问题,可为被动测距技术的进一步优化和应用提供理论支撑。     

氧分子A吸收带的随机Malkmus被动测距

针对比尔-朗伯定律单色传输和其他透过率模型计算速度慢的问题,为了实现红外目标的高速被动测距,研究了被动测距系统中氧分子A带吸收特征及大气中氧分子吸收率的计算方法。分析了大气中氧分子A带的吸收光谱及分布特性,以当前大气参数和测量环境为基础,结合HITRAN数据库,将随机Malkums带模式引入到氧分子带平均吸收率计算中,建立了基于随机Malkums带模式的被动测距数学模型。搭建了测距实验平台,在12~128m内对7个不同点进行了距离测量。实验结果表明,在实际大气条件下,利用该被动测距模型测得被测目标距离与实际距离的平均误差达到1.8%。该模型正确、可行,满足红外目标被动测距的高速在线测试及隐蔽性、高精度、抗干扰能力强等要求。     

电穿孔能量对药物经皮渗透速率的影响

经皮给药电穿孔技术是利用电穿孔脉冲作用在皮肤上,产生可逆水性电孔道,促进药物的经皮渗透速率。以往的研究都是高压脉冲,对实际应用造成困难。本文研究了电穿孔能量对盐酸丁卡因和萘普生经皮渗透速率的影响,探索低压电穿孔技术的途径。我们用１２０Ｖ,４．２Ｊ的方波电穿孔脉冲作用与雄性ＳＤ大鼠腹部皮肤,盐酸丁卡因经皮渗透速率比被动渗透提高５．１倍;用４００Ｖ,３７．６Ｊ的指数电穿孔脉冲作用与相同的大鼠皮肤,萘普     

Application of Hot Forming High Strength Steel Parts on Car Body in Side Impact

Lightweight structure is an important method to increase vehicle fuel efficiency.High strength steel is applied for replacing mild steel in automotive structures to decrease thickness of parts for lightweight.However,the lightweight structures must show the improved capability for structural rigidity and crash energy absorption.Advanced high strength steels are attractive materials to achieve higher strength for energy absorption and reduce weight of vehicles.Currently,many research works focus on component level axial crash testing and simulation of high strength steels.However,the effects of high strength steel pans to the impact of auto body are not considered.The goal of this research is to study the application of hot forming high strength steeI(HFHSS)in order to evaluate the potential using in vehicle design for lightweight and passive safety.The performance of HFHSS is investigated by using both experimental and analytical techniques.In particular,the focus is on HFHSS which may have potential to enhance the passive safety for lightweight auto body.Automotive components made of HFHSS and general high strength steel(GHSS)are considered in this study.The material characterization of HFHSS is carried out through material experiments.The finite element method,in conjunction with the validated model is used to simulate the side impact of a car with GHSS and HFHSS parts according to China New Car Assessment Programme(C-NCAP)crash test.The deformation and acceleration characteristics of car body are analyzed and the injuries of an occupant are calculated.The results from the simulation analyses of HFHSS are compared with those of GHSS.The comparison indicates that the HFHSS parts on car body enhance the passive safety for the lightweight car body in side impact.Parts of HFHSS reduce weight of vehicle through thinner thickness offering higher strength of parts.Passive safety of lightweight car body is improved through reduction of crash deformation on car body by the application of HFHSS parts.The experiments and simulation are conducted to the HFHSS parts on auto body.The results demonstrate the feasibility of the application of HFHSS materials on automotive components for improved capability of passive safety and lightweight.     

Evaluation of the health of riveted joints with active and passive structural health monitoring techniques

Many active and passive structural health monitoring (SHM) techniques have been developed for detection of the defects of plates. Generally, riveted joints hold the plates together and their failure may create accidents. In this study, well known active and passive methods were modified for the evaluation of the health of the riveted joints between the plates. The active method generated Lamb waves and monitored their propagation by using lead zirconate titanate (PZT) disks. The signal was analyzed by using the wavelet transformations. The passive method used the Fiber Bragg Grating (FBG) sensors and evaluated the spectral characteristics of the signals by using Fast Fourier Transformation (FFT). The results indicated that the existing methods designed for the evaluation of the health of individual plates may be used for inspection of riveted joints with software modifications.     

液压挖掘机主被动复合驱动回转系统特性及能效

液压挖掘机上车回转系统起动时,由于大惯性、高起动压力而造成大量的溢流损失;制动时回转动能转化为热能,能量损耗大。为此提出主被动复合驱动回转系统,在主驱动回转系统的基础上增设被动回路,被动液压马达用于降低主驱动液压马达的驱动功率及回收制动能量;为降低起动过程中的溢流损失,对主动回路采用进出口独立控制。针对主动马达和被动马达不同排量比对蓄能器压力的影响,提出了改变被动马达排量的优化方案。首先,进行元件匹配计算;然后,建立挖掘机主被动复合驱动回转系统联合仿真模型,与原机回转系统进行能耗对比。结果表明:主被动复合驱动系统在1个工作循环内能耗降低了35.9%~53.1%,实现了节能,提高了工作效率。     

局部粘弹性被动约束阻尼梁的振动分析

针对夹层约束阻尼梁结构的减振特性进行深入研究.应用粘弹性材料的耗能原理结合模态应变能法对局部粘弹性被动约束阻尼简支梁的振动特性进行数值分析,对梁铺设阻尼层前后的时域和频域特性分别进行比较,可以得出约束阻尼梁的振动得到有效抑制,同时看到模态应变能法对板梁结构的分析更便捷.     

基于混沌信号的光时域反射仪

研制了基于混沌信号相关测距技术的光时域反射仪样机。介绍了该仪器的混沌光源设计,硬件系统结构设计和软件算法流程设计。以G.652.B单模光纤为被测对象,对该仪器检测光纤故障的技术指标进行了分析测试。测试结果表明,在102km内可实现与距离无关的50cm空间分辨率,比现有飞行时间测量技术提高了约两个数量级,可实现对光纤不同类型反射事件的识别,完全满足无源光网络中的故障检测。     

欠驱动柔性机器人的动力学建模与耦合特性

运用有限元法,建立具有柔性杆的欠驱动机器人的动力学一般模型。以此模型为基础,分析系统的主动与被动关节的加速度耦合和被动关节与驱动力矩的动力学耦合效应,并针对欠驱动柔性机器人,提出柔性杆弹性变形分别与主动关节、被动关节动力学耦合的新指标。将欠驱动柔性机器人的被动关节加速度耦合和力矩耦合仿真结果与刚性系统相比较,在某个驱动器位置,柔性系统得到较大的耦合值,说明此时柔性系统更加有利于能量的传递,体现了杆件的弹性变形对系统动力学特性的影响。同时,数值仿真还表明这些动力学耦合指标对欠驱动机器人的结构设计、位形设计、驱动装置位置及系统控制都具有重要意义。     

管道导波检测中的位移圆周分布调制方法

在研究管道导波检测中的位移圆周分布调制聚焦技术时,将存在的缺陷看作一个新的导波源,提出通过截取阵列中各传感器获得的检测信号中的缺陷反射回波及转换模态波包信息,分析该波源造成的波场在检测位置的位移圆周分布,从而得到将检测能量重新聚焦于缺陷所在圆周任一位置所需要的各激励信号幅值系数和时间延迟参数.有限元分析及试验表明,应用该方法,不仅可以减少运用位移圆周分布调制聚焦技术检测时的计算量,还可以灵活地应对检测过程中管道参数、传感器阵列及检测频率的变化,有利于该方法的推广和应用.     

Sub-workspace design of binary manipulators using active and passive joints

This paper is concerned with an efficient continuous variable optimization method for determining an optimal configuration of passive and active joints of a binary manipulator when it operates within a desired sub-workspace. When joints are passive, their states, either stretched or contracted, are also determined by the developed method. Manipulator operations in a sub-workspace can avoid unnecessary actuations, resulting in energy saving. A technique to increase the sub-workspace concentration degree for a given maximum number of allowable active joints is also suggested.     

Seismic Signal Processing for Estimating the Path of a Moving Vehicle

The application of signal energy parameters to estimate the motion of objects with continuous influence on soil in systems of passive seismic location is considered. Statistics for measured values of signal powers with account for energy properties of the medium are proposed. The influence of displacement of the object on the ratio of signal powers on different sensors is analyzed. The results of testing the algorithm for estimating the parameters of the path of rectilinear motion of a car are given.     

A case study: passive component inspection using a 1D wavelet transform

This paper exploits a wavelet-based scheme to inspect the surface defects and basic dimensions of 0805 Multi-layer Ceramic Chip capacitors (MLCC) using machine vision. The image of a passive component is initially processed to show only two solder plates (terminations). Then, the covariance matrix eigenvector for each boundary point generates the 1D θ-p representation to describe the angle variations at the boundaries of each termination. The 1D θ-p representation is further decomposed directly by a one-dimensional wavelet transform (1D WT). Since a single corner (an intersection of two boundary edges) and the jag corners (the surface defects) are local deviations on termination boundaries, their locations are represented as intensive and have a highly fluctuated wavelet energy at the 1st detail scale. Concerning a 0805 MLCC type of passive component, the surface defects and single corners on termination boundaries can be captured by appropriate thresholds (e.g., in wavelet energy). The basic dimensions of a passive component are simply the direct distance between located single corners. Real 0805 MLCCs are testing samples to evaluate the performance of the proposed approach. Experimental results show that the proposed method achieves a precise identification of the surface defects and measurements for basic dimensions. The proposed approach is invariant with respect to the orientation, easy to implement and free from a primitive-matching process. Therefore, it is especially suitable for various types of passive components that are similar to the 0805 MLCC in small-batch production.     

An integrated approach to structural damping

This paper considers a passive damping method that can be applied to a wide range of structural geometries including machine tool bases and components. The method uses viscoelastic materials to dissipate energy in the manner of classic constrained-layer damping, however, the layers are embedded within the structure as opposed to being applied externally. This provides a robust means of incorporating damping without encountering several of the common disadvantages associated with external damping treatments. An analytical solution to the amount of damping in bending modes is presented using a modal strain energy approach. The utility of this passive damping technique is demonstrated experimentally, and examples showing the accuracy of the modal strain energy solution are presented.     

基于智能手机TDOA估计的被动声源定位方法与系统实现

被动目标监测广泛应用于国防、安全等领域。针对被动声目标监测,首次提出了基于手机平台的被动式声目标定位方法,并设计和开发了原型系统。针对手机间时钟同步对被动式信号到达时间差精度的影响,采用手机内置的麦克风和扬声器发送和接收同步声信号的方式,从而避免了节点间无线同步到声信号采集间的时间延迟不确定性。为了提高信号发送和接收时刻的估计精度,将时间戳信息调制到设定的线性调频声信号,并采用广义互相关方法来实现信号波形检测。进一步,针对被动目标声源的非合作特性,采用统计判决理论和语音活动性检测相结合的方法对观测信号进行联合检波,获得被动目标声源到达时间的高精度估计,即被动声源到手机间的到达时间差。最后,通过多部手机搭建了原型系统并设计实验,结果表明定位误差不超过10%的概率达到80%。     

Design and optimization for the occupant restraint system of vehicle based on a single freedom model

Throughout the vehicle crash event, the interactions between vehicle, occupant, restraint system (VOR) are complicated and highly non-linear. CAE and physical tests are the most widely used in vehicle passive safety development, but they can only be done with the detailed 3D model or physical samples. Often some design errors and imperfections are difficult to correct at that time, and a large amount of time will be needed. A restraint system concept design approach which based on single-degree-of-freedom occupant-vehicle model (SDOF) is proposed in this paper. The interactions between the restraint system parameters and the occupant responses in a crash are studied from the view of mechanics and energy. The discrete input and the iterative algorithm method are applied to the SDOF model to get the occupant responses quickly for arbitrary excitations (impact pulse) by MATLAB. By studying the relationships between the ridedown efficiency, the restraint stiffness, and the occupant response, the design principle of the restraint stiffness aiming to reduce occupant injury level during conceptual design is represented. Higher ridedown efficiency means more occupant energy absorbed by the vehicle, but the research result shows that higher ridedown efficiency does not mean lower occupant injury level. A proper restraint system design principle depends on two aspects. On one hand,the restraint system should lead to as high ridedown efficiency as possible, and at the same time, the restraint system should maximize use of the survival space to reduce the occupant deceleration level. As an example, an optimization of a passenger vehicle restraint system is designed by the concept design method above, and the final results are validated by MADYMO, which is the most widely used software in restraint system design, and the sled test. Consequently, a guideline and method for the occupant restraint system concept design is established in this paper.     

Target location method for pipeline pre-warning system based on HHT and time difference of arrival

The increasing serious pipeline leakage accidents are caused by third part damage. The third party damage activity around pipeline can generate seismic wave, and the seismic wave can be used for target identification and damage activity location. This paper presents a novel passive location method based on arrival time difference of specific seismic wave characteristic frequencies. The seismic signals are typically non-stationary and the conventional methods cannot analyze them well. Hilbert–Huang Transform (HHT), including empirical mode decomposition (EMD) and Hilbert transform, is a new time–frequency analysis method and can be used for seismic signals analyzing. Firstly, EMD is applied to process the signals and obtain the intrinsic mode functions (IMFs) features. The kurtosis features are used to identify targets and characteristic frequencies are selected as principal components according to IMFs energy features. These principal components are processed by windowed harmonic wavelet transform and then instantaneous features of seismic signals can be extracted. TDOA can be deduced from the arrival time difference of principal frequency components. Finally, target location can be achieved by the time difference analyzing, sensors layout and the relative position between sensors and targets. The seismic signals acquired from field experiment are analyzed and the results are discussed.     

Passive suppression of nonlinear panel flutter using piezoelectric materials with resonant circuit

In this study, a passive suppression scheme for nonlinear flutter problem of composite panel, which is believed to be more reliable than the active control methods in practical operations, is proposed. This scheme utilizes a piezoelectric inductor-resistor series shunt circuit. The finite element equations of motion for an electromechanically coupled system is derived by applying the Hamilton’s principle. The aerodynamic theory adopted for the present study is based on the quasi-steady piston theory, and von-Karrnan nonlinear strain-displacement relation is also applied. The passive suppression results for nonlinear panel flutter are obtained in the time domain using the Newmark-β method. To achieve the best damping effect, optimal share and location of the piezoceramic (PZT) patches are determined by using genetic algorithms. The effects of passive suppression are investigated by employing in turn one shunt circuit and two independent shunt circuits. Feasibility studies show that two independent inductor-resistor shunt circuits suppresses flutter more effectively than a single shunt circuit. The results clearly demonstrate that the passive damping scheme that uses piezoelectric shunt circuit can effectively attenuate the flutter.