A novel model reduction method based on balanced truncation

The main goal of this paper is to construct an efficient reduced-order model (ROM) for unsteady aerodynamic force modeling. Balanced truncation (BT) is presented to address the problem. For conventional BT method, it is necessary to compute exact controllability and observability grammians. Although it is relatively straightforward to compute these matrices in a control setting where the system order is moderate, the technique does not extend easily to high order systems. In response to the challenge, snapshots-BT (S-BT) method is introduced for high order system ROM construction. The outline idea of the S-BT method is that snapshots of primary and dual system approximate the controllability and observability matrices in the frequency domain. The method has been demonstrated for 3 high order systems: (1) unsteady motion of a two-dimensional airfoil in response to gust, (2) AGARD 445.6 wing aeroelastic system, and (3) BACT (benchmark active control technology) standard aeroservoelastic system. All the results indicate that S-BT based ROM is efficient and accurate enough to provide a powerful tool for unsteady aerodynamic force modeling.     

宽带跟踪雷达解线频调接收的回波相干化方法

为了降低采样带宽,提出了一种通过硬件粗控解线频调参考信号的延时,根据参考信号与基准信号的关系对参考信号延时误差所引入的多普勒相位误差进行精确补偿,从而可将逆合成孔径雷达中的解线频调回波相干化的新方法．此方法可以加快成像速度,并且对低信噪比条件下的逆合成孔径雷达成像非常有益．     

3+8×0.33HT钢帘线在全钢载重子午胎中的应用

由于子午线轮胎的受力特点不同于传统的斜交轮胎,其主要受力部件是轮胎的带束层,承受着轮胎60%以上的应力。因此,要求用于带束层的钢帘线在     

Dual-wavelength flash Raman mapping method for measuring thermal diffusivity of the suspended nanowire

In this paper, we present a dual-wavelength flash Raman (DFR) mapping method for measuring the thermal diffusivity of a suspended nanowire. A heating pulse     

化学计量学建模软件的开发及应用

本文利用数据库技术,针对Y=F(X)数学模型,编写集模型管理、数据样本管理和建模、预报为一体的通用性处理软件。软件自动适应不同分析体系中,自变量数和目标函数的变化,并支持在模型中对每个自变量进行定义,及其物理意义的显示。软件中提供了MLR、PCR、PLS、神经网络和遗传算法-PLS联用5种建模方法,并将交叉验证方法嵌入PCR、PLS方法中,用交叉验证法检验样本中的奇异样本点。利用模拟数据对软件进行了检验。     

国外电子废弃物的回收利用技术

一、电子废弃物的成分及危害 电子废弃物（WEEE）主要是指家用电器、计算机、通信设备、工业控制设备等电子产品使用后报废或淘汰的、不能再用作原用途的废弃物。     

基于知识点的试题库组卷算法的建立

试题组卷算法的优劣直接影响到试题库的性能。本文在分析基于知识点的试题库结构的基础上,阐述以知识点、难度系数和题型为主要控制参数的组卷算法的建立与实现方法。     

基于连续响应表面法的汽车结构耐撞性仿真优化

汽车结构的耐撞性及碰撞吸能优化是现代汽车工业重要的研究内容.耐撞性的优化涉及到材料与结构的众多参数,传统的设计、仿真及碰撞试验往往只能在一定程度上改善结构的碰撞性能,而无法达到限定条件下的最优状态.为解决汽车碰撞的优化问题,文中采用连续响应表面方法,通过变量筛选技术和一阶线性响应表面模型,并结合非线性有限元程序进行全局寻优.汽车前端结构的耐撞性优化表明,该方法具有较高的精度和稳定性.     

邯峰发电厂"W"形火焰锅炉IK555型长杆吹灰器的问题及其分析

对邯峰发电厂的吹灰器系统进行了简要说明,对运行中长杆可伸缩吹灰器发生的问题进行了分析,并提出了解决方案。     

Effect of carbon nanotube on the electrochemical performance of C-LiFePO4/graphite battery

This paper describes the fabrication and testing of C-LiFePO₄/graphite battery with different conductive carbon additives: carbon nanotube (CNT) or carbon black (CB). The discharge capacity, rate capability and cyclic performance of the battery were investigated. Compared with the batteries with CB additive, those with CNT additive show better electrochemical performances with capacity retention ratio of 99.2% after 50 cycles, and the ratio of discharge capacity at 0.1 C rate to that at 1 C rate is 94.6%. The reason for the difference in electrochemical property was studied with cyclic voltammagrams and AC impedance. It was found that, with CNT additive, the polarization voltage was decreased from 0.3 to 0.2 V, and the impedance was decreased from 423.2 to 36.88 Ω. The structures of active materials after cycling were characterized using XRD. The better crystal retaining of LiFePO₄ was found in the active materials with CNT added.