Automatic target recognition of moving target based on empirical mode decomposition and genetic algorithm support vector machine

In order to improve measurement accuracy of moving target signals, an automatic target recognition model of moving target signals was established based on empirical mode decomposition(EMD) and support vector machine(SVM). Automatic target recognition process on the nonlinear and non-stationary of Doppler signals of military target by using automatic target recognition model can be expressed as follows. Firstly, the nonlinearity and non-stationary of Doppler signals were decomposed into a set of intrinsic mode functions(IMFs) using EMD. After the Hilbert transform of IMF, the energy ratio of each IMF to the total IMFs can be extracted as the features of military target. Then, the SVM was trained through using the energy ratio to classify the military targets, and genetic algorithm(GA) was used to optimize SVM parameters in the solution space. The experimental results show that this algorithm can achieve the recognition accuracies of 86.15%, 87.93%, and 82.28% for tank, vehicle and soldier, respectively.

STABILITY AND LOCAL BIFURCATION IN A SIMPLY-SUPPORTED BEAM CARRYING A MOVING MASS

The stability and local bifurcation of a simply-supported flexible beam （Bernoulli- Euler type） carrying a moving mass and subjected to harmonic axial excitation are investigated. In the theoretical analysis, the partial differential equation of motion with the fifth-order nonlinear term is solved using the method of multiple scales （a perturbation technique）. The stability and local bifurcation of the beam are analyzed for 1/2 sub harmonic resonance. The results show that some of the parameters, especially the velocity of moving mass and external excitation, affect the local bifurcation significantly. Therefore, these parameters play important roles in the system stability.

Vibration Analysis of a Simply Supported Beam Traversed by Uniform Distributed Moving Load

Considering the engineering background of some transportation system like maglev, vertical vibration of the simply supported beam is investigated. The length of the vehicle is assumed to be longer than the beam span. The model of moving distributed load with constant speed is established .The beam can be taken as Euler-Bernoulli beam model and the right side of the control equation is simplified by using a moving status function. Duhamel integral and mode superposition method is used to solve the dynamic behavior of the beam. In this aspect deflection and acceleration are included. The results of different parameters such as the span of beam, velocity of load and ratio vehicle-Beam masses are compared. All results show that the dynamic response of the beam is tied up with these factors: the frequency of the beam, the moving frequency of the load and the ratio of vehicle-beam mass.

FE Dynamic Analysis Using Moving Support Element on Multi-Span Beams Subjected to Support Motions

In the present study, finite element dynamic analysis or time history analysis of two-span beams subjected to asynchronous multi-support motions is carried out by using the moving support finite element. The elemental equation of the element is based on total displacements and is derived under the concept of the quasi-static displacement decomposition. The use of moving support element shows that the element is very simple and convenient to represent continuous beam moving, deforming and vibrating simultaneously due to support motions. The comparison between the numerical results and analytical solutions indicates that the FE result agrees with the analytical solution.

Damage Identification in Simply Supported Bridge Based on Rotational-Angle Influence Lines Method

To locate and quantify local damage in a simply supported bridge, in this study, we derived a rotational-angle influence line equation of a simply supported beam model with local damage. Using the diagram multiplication method, we introduce an analytical formula for a novel damage-identification indicator, namely the diff erence of rotational-angle influence linescurvature(DRAIL-C). If the initial stiff ness of the simply supported beam is known, the analytical formula can be effectively used to determine the extent of damage under certain circumstances. We determined the effectiveness and anti-noise performance of this new damage-identification method using numerical examples of a simply supported beam, a simply supported hollow-slab bridge, and a simply supported truss bridge. The results show that the DRAIL-C is directly proportional to the moving concentrated load and inversely proportional to the distance between the bridge support and the concentrated load and the distance between the damaged truss girder and the angle measuring points. The DRAIL-C indicator is more sensitive to the damage in a steel-truss-bridge bottom chord than it is to the other elements.

Association Rules Mining Based on SVM and Its Application in Simulated Moving Bed PX Adsorption Process

In this paper, a novel data mining method is introduced to solve the multi-objective optimization problems of process industry. A hyperrectangle association rule mining （HARM） algorithm based on support vector machines （SVMs） is proposed. Hyperrectangles rules are constructed on the base of prototypes and support vectors （SVs） under some heuristic limitations. The proposed algorithm is applied to a simulated moving bed （SMB） paraxylene （PX） adsorption process. The relationships between the key process variables and some objective variables such as purity, recovery rate of PX are obtained. Using existing domain knowledge about PX adsorption process, most of the obtained association rules can be explained.

Danger Detection during Fight against Compartment-Fire Using Moving Averages in Temperature Recordings

In compartment fires (houses, buildings, underground, warehouse, etc.), smokes are a major dan- ger during firemen intervention. Most of the time, they are at high temperature (>800?C) and they flow everywhere through many kinds of ducts, which leads to the propagation of the combustion by the creation other fires in places which may be far away from the initial fire. In this paper, we present a new approach of the problem, which allows to better follow the fire behavior and especially to detect the dangers that may appear and endanger firefighters. This approach consists in a mathematical analysis based on the comparison of moving averages centered in the past, calculated on the temperature recordings of the smokes. As a consequence, this method may allow to improve decision support in real time and therefore to improve the security and the efficiency of firefighters in their operations against that kind of fires.

综采工作面分布式蓄能供液系统研究及应用

为解决综采工作面跟机移架速度慢的问题,提出了基于蓄能器的分布式供液系统,并在柠条塔S1204工作面开展了试验应用。根据工作面的采煤工艺和产能要求确定了跟机移架速度,建立了全工作面供液系统仿真模型,对液压支架单架、双架和三架同时移架的动作过程进行模拟并分析影响移架时间的因素,结果表明:为使工作面生产能力提升到1000万t/a,中部液压支架跟机速度要达到12 m/min以上,需采用双架或三架成组移架来满足其移架时间的要求。为解决该工况压力波动大且易产生丢架的现象,提出在液压支架上设置“蓄能器+单向阀”的分布式蓄能稳压方案,以平衡工作面液压系统瞬时大流量供给不足与平均供液能力过剩的矛盾,并给出了基于流量补偿的蓄能器选型方法。仿真分析表明在安装分布式稳压供液系统后,双架和三架成组移架时间分别减少6.2%和11.5%,尤其在受到其他系统用液扰动条件下,双架成组移架时间可缩短15%以上。井下应用结果表明,安装的分布式蓄能供液系统显著降低了成组拉架中的丢架现象,保证了采煤机运行速度达12 m/min以上;对工作面平均日进尺由16.7刀提高到19.8刀起到重要支撑作用,实现了常态化日进尺22刀,达到了年产1000万t的生产能力,研究工作为综采工作面快速成组跟机移架提供了有效解决方案。

基于移动荷载谱的高速铁路简支梁桥基频限值分析

控制桥梁振动响应是保证高速列车安全稳定运行的关键,遵循梁体不发生共振或较大位移响应的原则,提出了简支梁桥基频限值频域分析法。首先基于移动荷载列模型,通过傅里叶变换得到了桥梁振动响应谱和移动荷载谱,并从时域角度验证了谱的正确性;然后通过引入间跨比γ和无量纲速度κ,探究了在不同移动荷载列作用下桥梁自由振动发生最大位移响应时,无量纲速度κ和间跨比γ之间的关系;其次根据γ-κ关系曲线分析了24 m、32 m、40 m简支梁桥最大位移响应下的无量纲速度κ;最后为了避免列车激励下桥梁发生共振或较大位移响应,参考国际铁路联盟基频限值规范,基于移动荷载谱给出了移动荷载列在不同设计时速下24 m、32 m、40 m简支梁桥基频限值建议值。研究表明:移动荷载幅值谱与时域计算的桥梁自由振动位移幅值响应规律一致;单节车长25 m左右的移动荷载列以共振速度激励桥梁时,24 m、32 m简支梁桥自由振动都能达到最大位移响应,而40 m简支梁桥仅产生较大位移响应,且在列车运营速度范围内达不到产生最大位移的条件;桥梁基频限值随着列车时速的增加而增大,当最大设计时速400 km/h时24 m、32 m、40 m简支梁桥基频建议下限值分别为6.00 Hz、4.94 Hz、5.66 Hz。

基于SARIMA和SVR组合模型的转向架系统寿命评估

随着地铁运营时间和里程的增加,地铁车辆逐渐接近其理论寿命,为确保车辆运行安全性,需对其重要子系统进行健康状态及剩余寿命评估。文中选取车辆转向架系统作为研究对象,提出了一种基于协方差优选法的季节性回归移动平均(SARIMA)和支持向量回归(SVR)的组合模型对转向架寿命进行评估。首先,将车辆转向架系统历史故障率转化为健康指数,然后基于协方差优选法将SARIMA和SVR进行赋权组合,根据转向架系统历史健康指数进行预测,最后建立历史和预测的健康指数与运行时间的数学模型,分析得到转向架系统的剩余寿命。以某地铁车辆转向架系统为例进行算例分析及验证,结果表明组合模型可更准确地预测其健康状态,为有关维修部门开展维修维护策略提供理论依据,估计得出其剩余寿命,为车辆寿命后期退役及延寿决策提供理论数据分析支撑。

基于TRIZ的全断面铺锚支机器人结构创新设计

为解决煤矿巷道掘进过程中支护、铺网、钻孔及锚固等工序自动化水平低、难以高效协同等技术难题,基于TRIZ理论,开展全断面铺锚支机器人的结构创新设计。通过九屏分析法、功能模型图与因果轴分析得出现有铺锚支机器人效率不足的根本原因,并综合运用技术矛盾法、物理矛盾法以及76种标准解等方法,设计出新型全断面铺锚支机器人结构,进而通过ADAMS-AMESim联合仿真,开展其关键迈步式自移支架的机液耦合分析。结果表明:全断面铺锚支机器人具备迈步行走、铺网、支护、锚固、钻孔的平行作业;迈步式自移支架工作时推移缸的最大推架力为10940 N,最大拉架力为18510 N,实际位移与理想位移误差满足设计要求。

基于SARIMAX-SVR的光伏发电功率预测

为提高光伏发电功率预测精度,提出一种基于外生因素及季节性的差分自回归移动平均SARIMAX(seasonal autoregressive integrated moving average with exogenous factors)并结合优化支持向量回归SVR(support vector regression)的光伏发电功率预测方法。首先,采用相关性特征法聚类气象条件中关键气象因子,以消除数据冗余并降低ARIMAX模型的复杂性;其次,在ARIMAX模型中引入季节性因素,构建SARIMAX模型来捕捉数据的季节性变化;最后,使用SARIMAX模型的拟合残差其作为SVR模型的输入,进一步拟合数据的非线性。通过仿真算例分析表明,所提方法可显著提高光伏发电功率预测精度。

星载迈克尔逊干涉仪直线动镜的柔性支撑结构研究

针对传统迈克尔逊干涉仪动镜支撑结构存在成本高、寿命低、维护难度大、大行程大负载下导向精度差的问题,设计了一种高精度迈克尔逊干涉仪角镜柔性支撑结构,具有低成本、高精度、大负荷的优点。提出以柔性支撑结构的承载能力、行程和导向精度为优化目标的结构刚度模型,选择材料和尺寸参数,开展运动结构设计。有限元分析结果表明该支撑结构在1.5 kg的负载(角镜)下,当行程达到4.5 mm时,柔性结构的最大拉应力约为169 MPa,结构安全裕量为1.98,角镜竖直方向的寄生位移小于4.1μm。专项测试结果显示,支撑结构承载1.5 kg负载(角镜)在4.5 mm行程内,竖直方向的寄生位移小于4.7μm,直线度的均方根误差为1.5μm,与设计结果较吻合,可以满足星载迈克尔逊干涉仪对高精度直线动镜的支撑要求。

基于切比雪夫拟谱法的移动荷载作用下简支梁动力响应计算

采用切比雪夫拟谱法求解移动荷载作用下简支梁的动力响应问题,该方法通过重新选取插值点的方式并借助转换矩阵对边界条件进行施加,对集中荷载采用高斯函数法进行正则化处理。将本文方法计算结果与解析解和有限元解进行比较,结果表明,在划分较少单元数量时,采用本文方法计算结果与解析解吻合良好,求解效率高于有限元方法。采用本文方法对Dirac函数的正则化参数σ_(n)进行敏感性分析,结果表明,当在±3σ_(n)范围内布置配点数6~10个时,计算结果能取得较好的精度。

简支矩形薄壁箱梁受不确定移动偏载作用的竖向振动响应研究

针对工程中薄壁箱梁受不确定移动偏载作用的振动问题,给出了一种基于区间过程的求解简支矩形薄壁箱梁结构竖向振动响应边界的方法.基于修正Timoshenko梁理论、乌氏第二理论和箱梁畸变理论,求得了移动偏载作用下考虑截面扭转和畸变的简支矩形薄壁箱梁受迫竖向振动解析解,通过引入区间过程描述移动偏载的不确定性,推导了简支矩形箱梁竖向振动响应边界的计算过程,分析了不确定性参数的相关性和荷载速度对简支矩形薄壁箱梁竖向振动响应的影响,与有限元计算结果对比验证了本文方法的正确性.

矩形巷道自移式支护设备的结构设计与仿真

针对自移式临时支护设备对复杂巷道环境适应性差、液压支柱弯曲变形,以及铺网面积小的问题,设计了一种适用于矩形巷道带有铺网装置的自移式支护设备,介绍了其主要组成结构、工作原理以及主要技术参数。并利用ANSYS软件对单组伸缩式门型支架进行了仿真分析,结果表明,其结构强度与变形量均在允许范围内。对有无辅助支撑工况下的底座进行仿真对比,结果表明,底座的辅助支撑可以有效减小支柱变形量与等效应力,进而保证了支架工作时的稳定性,提高了支护的安全性。

履带自移式可调节液压支架的设计

介绍了目前煤矿井下机载临时支护装置、迈步式临时支护装置及无反复支撑式支护装置存在的缺陷,提出了新型的履带自移式可调节液压支架设计方案。该液压支架采用门式结构和多柱支撑式顶梁,同步跨骑于掘进机或锚杆钻车上方,可适应掘进、支护时间和空间的要求,实现了巷道掘进过程掘支平行零空顶支护作业,大幅提高了掘进效率。

液压支架液控系统的动态特性分析

为提升液压支架液压系统工作效率,应用AMESim仿真软件分析支架立柱液控系统动态特性,表明增大泵站流量可明显提升升柱速度,对降柱速度影响小;缩短伸缩杠位移,可缩短升降柱时间;增大液控单向阀直径、供液管路直径,可提升升降柱速度,并在液控系统最优参数组合下,升柱时间为3.5 s,提升约17%;立柱降柱时间为2.1 s,提升约16%,提升液压支架立柱控制系统效率.

既有建筑狭窄空间区域改造加固施工技术研究

文中结合某大型商场项目施工实践,对既有建筑狭窄空间区域改造加固施工技术进行分析,并监测其施工效果。结果表明,楼板的竖向位移和侧向位移均满足设计要求,加固后构件的抗变形能力提升了62.3%,验证了上述所用加固施工技术的可靠性。所采用的施工技术具有缩短施工周期、节约施工成本、使用性能良好的特性,为后期类似的改造加固工程提供一定参考。

综采工作面柔性自适应液压支架防尘装置设计与应用

为了解决大采高综采工作面支架间人员作业区域粉尘污染严重的问题,采用现场调研方法,分析得出支架掩护梁与顶梁铰接的部位是降柱移架产尘的主要位置,需要重点治理;通过对胶皮与滑槽为主要结构的支架防尘装置动作过程的分析,得出刚性滑槽由于受力不平衡而产生扭转,提出以胶皮为主要结构的柔性自适应液压支架防尘装置,并对其有效性和可靠性进行了现场试验。现场应用表明:该装置降尘效率达94%以上,显著改善了综采工作面下风侧人员作业区域的环境卫生条件;接尘导尘组件将落尘全部导入架间,极大降低了工人清理的工作量。