汽雾冷却条件下转炉炉体瞬态温度场

通过有限元方法,对汽雾冷却条件下大型转炉炉体瞬态温度场进行了三维有限元仿真分析及宝钢300 t大型转炉热电偶数据实测,研究了该条件下炉体瞬态温度场的分布及变化规律.实测的炉壳温度及其变化规律与有限元仿真结果吻合较好,证实了炉体瞬态温度场有限元分析的可信性.研究结果表明,汽雾冷却条件下炉壳温度呈锯齿形波动(降温速度快,升温较慢),平均降温速度为2～2.5℃/min.运用汽雾冷却技术,可将炉壳温度控制在材料热蠕变温度(约400℃)以下,有效抑制了炉壳热蠕变变形.     

A new calibration model of camera lens distortion

Lens distortion is one of the main factors affecting camera calibration. In this paper, a new model of camera lens distortion is presented, according to which lens distortion is governed by the coefficients of radial distortion and a transform from ideal image plane to real sensor array plane. The transform is determined by two angular parameters describing the pose of the real sensor array plane with respect to the ideal image plane and two linear parameters locating the real sensor array with respect to the optical axis. Experiments show that the new model has about the same correcting effect upon lens distortion as the conventional model including all the radial distortion, decentering distortion and prism distortion. Compared with the conventional model, the new model has fewer parameters to be calibrated and more explicit physical meaning.     

Theoretical and experimental research on the in-plane comb-shaped capacitor for MEMS coriolis mass flow sensor

The Micro-Electro-Mechanical System Coriolis mass flow sensor uses a kind of in-plane comb-shaped capacitor to detect the vibration of tube containing the micro flow information. This paper takes the deflection of the micro tube caused by Coriolis force into account and models the in-plane comb-shaped capacitor of the sensor based on the electrostatic field method. Then the modulation and demodulation of the output capacitive signals are described in detail. The theoretical waveforms obtained by substituting the actual parameters into the models are consistent with the accepted conformal mapping method and match with the sampling signals, which attest the two models. According to the actual flow calibration experiment and the preliminary phase shift calculation, the measurement accuracy of the micro flow sensor reaches ±1.5 % with the repeatability of 0.75 % within 0–1.2 g/h flow range.     

基于视觉的远场激光光束质量的检测方法

介绍了一种远场激光光束质量的检测方法,可检测远场激光的光斑位置、光斑大小和光强分布。漫反射特性的靶板在远场接收激光,采用视觉系统以一定角度拍摄靶板图像,采用VC++编制软件对图像进行处理,得出检测参数。给出了系统的组成和图像处理算法,并进行了检测精度测试,光斑位置测量误差小于2 mm。实验结果表明,视觉系统不需要标定,测量方便,可在野外现场检测。     

An I-shape linear piezoelectric actuator using resonant type longitudinal vibration transducers

Resonant type longitudinal vibration transducers are used in this work to construct a linear piezoelectric actuator with four driving feet. Totally three longitudinal transducers are integrated in I-shape to form the proposed actuator, which contains one vertical transducer and two horizontal transducers. These three transducers vibrate under longitudinal modes with certain temporal sequence, whose vibrations are superimposed in the actuator to generate elliptical motions on the four driving feet. The three transducers are tuned to be suitable dimensions, under which they have very close 1st longitudinal resonance frequencies; the working frequency of the piezoelectric actuator is designed to be about 31.3 kHz. The vibration coupling problem between the longitudinal transducers are studied by calculating the motion trajectories of the four feet. It is found that the temporal shift of the longitudinal vibrations can be used to tune the movement trajectories; the four feet can get nearly the same vertical displacements under a phase shift of 105°. At last, the vibration characteristics and mechanical output performances of a prototype are measured. The working frequency of the prototype, the maximum speed, and the maximum thrust force are measured to be 33.15 kHz, 1563 mm/s, and 158.2 N, respectively.     

寄生式时栅传感器动态测量误差的贝叶斯建模

为了提高寄生式时栅传感器的测量精度,分析了它的工作原理和动态误差组成,得到其主要误差分量为常值误差、周期误差和随机误差等。针对寄生式时栅误差特点,建立了寄生式时栅动态误差高精度预测模型,并与其他建模方法进行了比较。选用插入标准值的贝叶斯预测模型,以实际测量的传感器第一个对极动态误差数据进行建模,在后续对极特定位置插入部分实际误差测量数据,建立误差预测模型,预测了传感器后83个对极的动态误差。另选用三次样条插值和BP神经网络建模方法对寄生式时栅整圈动态误差建模,并与建立的误差模型进行了对比。验证实验表明,三次样条插值建模时间最短(0.62s),但其建模精度不高(16.050 0″);贝叶斯动态模型建模时间(0.86s)略长于三次样条插值,但建模精度最高(0.415 3″);BP神经网络建模时间最长(32min),但建模精度最低(19.680 2″)。同时贝叶斯插入标准值建模方法所需数据点(69395个)远少于三次样条和BP神经网络建模数据点(235526个),节省了大量的标定时间和建模数据量,因此可用于寄生式时栅传感器的动态测量误差高精度建模修正。     

磁悬浮分子泵用Hartley涡流传感器

工业领域的磁悬浮分子泵用位移传感器除了要具有良好的静态特性外,还应具有高动态响应特性,同时其体积大小还影响着磁悬浮分子泵的抽速、真空度和压缩比。针对高真空磁悬浮分子泵,提出了一种基于Hartley原理的电涡流位移传感器设计方法,将传感器对称探头接入同一振荡电路作为工作电感。对传感器的动态特性进行了分析,并提出了对其动态响应特性在不影响灵敏度和线性度等静态性能的情况下进行补偿的方法。实验结果表明,在-0.4~0.4mm内,传感器的线性度为±1.17%,灵敏度为9.901mV/μm,分辨率为0.25%,动态响应带宽达到了10.2kHz,两径向四路位移信号测量集成电路板体积仅为π×4~2 cm~2,大大减小了传感器体积,满足了磁悬浮分子泵面向更高抽速和更高真空度的发展需求。     

Sparse recovery formulation for secure distance-based localization in the presence of cheating anchors

Wireless Networks - Secure localization in the presence of cheating anchors is a critical issue in wireless sensor networks, where compromised anchors attempt to falsify the measured distances in...     

微细电解加工用中空电极的制备

为了改进加工间隙内电解产物的排出条件和加速电解液的更新,提出了一种嵌套式微细中空电极的精确可控焊接制备工艺。仿真分析了电极的过流特性,优化了电极长度,并进行了性能测试及加工实验。通过穿丝、黏结、嵌套尺寸及位置调整和焊接工序,制备出加工段内径为65μm、外径为130μm、长3.25mm左右,后段便于装夹和连通的嵌套式中空电极。在供液压力为1.15 MPa时,其出口流速可达10m/s左右。利用制备的中空电极,开展微细孔电解加工实验,在0.5mm厚不锈钢片上加工出最小入口孔径约为157μm,出口孔径约为133μm的微细孔,并将其延伸应用于微结构加工中,铣削出了长554μm、宽160μm、深224μm的微细T型槽。实验结果表明:制备的微细中空电极有效提高了加工间隙内电解液的流动特性,且连/导通可靠、装夹方便,适用于高深宽比微结构的电解加工。     

Adaptive fuzzy logic-based framework for software development effort prediction

Algorithmic effort prediction models are limited by their inability to cope with uncertainties and imprecision present in software projects early in the development life cycle. In this paper, we present an adaptive fuzzy logic framework for software effort prediction. The training and adaptation algorithms implemented in the framework tolerates imprecision, explains prediction rationale through rules, incorporates experts knowledge, offers transparency in the prediction system, and could adapt to new environments as new data becomes available. Our validation experiment was carried out on artificial datasets as well as the COCOMO public database. We also present an experimental validation of the training procedure employed in the framework.