基于鲁棒H~∞滤波的光电跟踪机动目标状态预测估计

针对光电跟踪系统中目标机动的特点和电视图像跟踪器信号处理、传输造成的测量时滞以及目标信号测量中存在的不确定干扰和噪声,选取机动目标"当前"统计模型对加速度进行建模,在所建立的光电跟踪目标加速度非零均值相关模型的基础上,采用鲁棒H∞滤波算法对光电成像识别目标运动状态进行预测估计.其预测精度比Kalman滤波提高近1倍.实验结果表明,该方法能有效地克服目标模型变化及随机噪声和干扰不确定性的影响,具有较高的预测精度和良好的鲁棒性.     

改进的粒子滤波在深空探测自主天文导航中的应用

针对深空自主天文导航中可能存在初始状态误差较大、状态分布非高斯分布等问题,基于轨道6根数描述形式,提出了利用星光角距观测信息和UPF（Unscented Particle Filter）算法确定探测器轨道的方法.通过控制重采样频率,使UPF获得更高的滤波精度和更少的计算量.最后经仿真计算,验证了所给出的自主天文导航方法以及改进的粒子滤波算法的可行性和有效性.     

基于改进 Kalman 滤波分布式航天器相对位置的解算

用Kalman滤波算法解算分布式航天器相对位置,与点估计法比较可提高定位精度．但传统Kalman滤波常会出现滤波发散的现象,影响滤波精度．通过研究克服传统Kalman滤波发散的方法,设计了一种改进的Kalman滤波算法,主要从初始值的设计及自适应调节两方面进行了改进．根据分布式航天器相对位置的状态方程和观测方程,利用该算法对相对位置进行了仿真解算．仿真结果表明,该算法用于分布式航天器相对位置的解算中三轴的滤波精度都可达到厘米级,与传统Kalman滤波算法相比,该算法可有效地克服滤波发散,提高滤波精度．     

时域模态参数辨识的状态滤波算法

本文针对结构模态参数辨识的噪声干扰问题,采用一种状态滤波方法削弱测量噪声的影响,避免了传统Kalman 滤波法中对系统模型的较高精度要求,并与特征系统实现算法(ERA)相结合,有效地克服了ERA 方法在信噪比较低的情况下对非零奇异值判断的困难,并更精确地识别出结构的模态参数。     

基于Kalman算法的软测量技术在电池容量检测中的应用

针对如何在线准确检测实际工作中发射车车载电池容量,提出了一种基于Kalman算法的软测量方法。首先,建立蓄电池数学模型,选择可测、易测的辅助变量,利用Kalman算法建立软测量模型;然后,使用试验数据,通过参数辨识求解软测量模型;最后,利用Matlab软件对该模型进行仿真以及现场试验。结果表明:采用Kalman算法的软测量技术减少了电池应用过程中的电流累积误差,提高了电池容量的检测精度。     

基于UKF的星载GPS自适应定轨方法

将UKF(Unscented Kalman Filter)方法应用于空间目标的星载GPS自主定轨中。着重介绍基于UT变换的UKF算法,针对系统噪声方差阵未知或动力学模型不精准的情况,提出在进行状态滤波的同时,利用观测数据信息,在线估计未知噪声的统计特性,构成状态噪声统计估计的自适应UKF滤波算法。结合实测CHAMP星载GPS数据进行仿真实验,对比发现滤波精度、稳定性均有所提高,证明该算法在星载GPS低轨卫星定轨中的有效性。     

基于卡尔曼滤波的旋转弹药弹体磁场校正方法

针对弹体磁场严重影响旋转弹捷联地磁传感器的测量精度这一问题,提出一种基于卡尔曼滤波算法(Kalman filter, KF)的弹体磁场校正方法。利用固定磁场和感应磁场模型,将弹体磁场误差系数转换到椭球参数方程上,从而得到卡尔曼滤波的观测方程。为提高算法的鲁棒性,采用事先标定法建立初始条件。根据卡尔曼滤波原理,给出辨识参数在线更新的实现步骤,推导弹体磁场的校正过程。仿真试验中,通过事先标定法选取初值提高待估参数2倍的收敛速度。转台试验中,弹体磁场校正后的磁测误差接近磁传感器的测量噪声,滚转角解算精度优于1°。试验验证该算法可在线更新弹体磁场误差系数,实现弹体磁场的高精度补偿。     

基于Kalman-GARCH模型的结构损伤识别

基于监测数据的结构损伤识别,是桥梁健康监测系统发挥感知预警效益的重要基础。为进一步提高结构损伤识别精度,提出一种融合Kalman滤波与广义自回归条件异方差(GARCH)模型的结构损伤识别方法。采用Kalman滤波对加速度时程数据进行降噪处理,在此基础上,建立了线性递归AR模型,对结构损伤进行识别;引入非线性递归GARCH模型,进一步提高识别精度;利用加速锈蚀损伤钢筋混凝土梁动力试验获取的加速度时程数据,对算法的有效性进行验证。结果表明:以损伤前后时间序列模型残差方差比为特征指标,能够有效识别结构损伤;与Kalman-AR模型相比,Kalman-GARCH模型能够解释部分非线性特征,弥补AR模型忽略数据异方差性所带来的识别误差,识别精度提高了14.2%。该方法可为基于海量数据的桥梁结构状态感知提供一种新的思路。     

卫星跟踪中位置预测的序列匹配算法

针对卫星跟踪中的位置预测问题,分析了动力学模型方法的预测误差组成,提出一种用测量数据来计算预测数据时间误差的序列匹配算法,并讨论了空间误差的计算方法。仿真结果表明,提出的时间校正和空间误差补偿方法的预测精度比动力学模型和Kalman滤波法的预测精度高;即在相同的精度要求下,序列匹配算法能预测的时间范围是Kalman滤波法的1.5倍以上。     

非线性系统的小波分频的扩展Kalman滤波

基于噪声的小波变换特点,结合量测的多尺度分解和扩展Kalman滤波(EKF),提出了一种小波“最佳”尺度分解的分频EKF滤波算法。该算法依据小波变换模功率谱选择最佳小波分解尺度,并将小波多尺度分解去噪和分频EKF滤波结合起来。对实际中含强噪声的非线性动态系统进行状态估计效果较好。Monte-Carlo仿真表明,与普通EKF滤波相比,本文算法的滤波精度平均提高约10%。     

Geometric and energy scaling for celestial impacts

In this study the applicability of geometric and energy scaling to crater geometry metrics for typical celestial impacts is considered. Numerical experiments, conducted over an impact velocity and obliquity range of 12–24 km/s and 0–82.5°, respectively, have been considered. In this analysis we have extended the results from previous work to include the influence of impact velocity. Impactor and target materials used in the analysis were generic iron and sandstone, respectively. A detailed mesh resolution and target size study was first performed to insure numerically resolved solutions and semi-infinite behavior in the target. An interesting finding is that the lateral dimensions of the target required to insure semi-infinite confinement are roughly 100 times the diameter of the impactor, compared to the roughly 30 diameters typically required for steel targets. Results of the scaling study quantitatively validated many of the conclusions obtained only in a qualitative sense from previous work. For example, the crater volume does not scale with the vertical component of the velocity, and the crater depth does not scale with the cube root of the energy based on the vertical component of the velocity.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.