行人头部撞击汽车发动机罩盖的多波峰特征与结构设计

为了解汽车发动机罩盖的结构设计对行人头部冲击响应的影响机理,提出了一种结构设计。根据行人头部冲击器与发动机罩盖碰撞加速度波形的多个波峰的特征,划分为不同阶段;分析了罩盖的碰撞变形过程和吸能机理,各阶段分别受罩盖随动质量、结构刚度、边界支撑及下方变形空间等因素的主导;对各主导因素进行补偿,以实现最优波形的罩盖结构设计方法。以某量产车型作为工程应用实例,给出了具有夹层板结构的发动机罩盖设计方案。结果表明:该设计能够改善行人头部碰撞保护性能,为发动机罩盖设计提供参考。

局部阴影下光伏阵列呈多波峰特性的MPPT算法研究

带有旁路二极管的光伏组件在局部阴影的遮蔽下,其输出的P-U特性是由多个局部峰值构成的非线性曲线,使传统的单峰MPPT算法无法准确跟踪最大功率点。通过建立并分析局部阴影下光伏组件的数学模型可避免陷入局部峰值。在传统电导增量法寻找峰值的基础上,应用聚拢峰值扫描判别法,分别从短路电流和开路电压处向中间聚拢扫描峰值并比较大小,直到找出真正的最大功率点。仿真结果表明,该算法在局部阴影下不会陷于局部峰值,能够快速跟踪最大功率点,明显提高了系统的光电转换效率。

多波峰光伏MPPT算法研究与应用

针对光伏发电系统中单峰值算法的缺陷,本文提出一种多波峰光伏MPPT算法。首先就单峰值算法存在的问题做了简单分析,接着介绍了MPPT算法的原理研究、建模及实现过程,并列举了实际应用范例,包括相应的负载装置、两级式电路结构两种设计,验证了本算法的增益效果及描述适用的应用领域。

圆筒装置内爆炸压力载荷特性实验研究

为了研究密闭环境压力载荷波形特征和分布规律,开展了长径比2∶1圆筒装置的TNT装药内爆炸实验,获取了圆筒壁面、端盖板表面的压力载荷数据,结合仿真计算结果,研究了圆筒壁面、端盖板上压力载荷波形特征和形成机理,建立了压力载荷峰值的表征模型,并开展了模型验证。结果表明,圆筒壁面与盖板压力载荷波形不完全相同,壁面压力载荷按照爆心距由近到远,从显著的单波峰向多峰值变化,在近场区域压力载荷衰减特性与一定炸高自由地面冲击波类似;盖板上压力载荷呈多波峰特点,中心区域压力载荷最大峰值大于首峰值的3倍,角隅区域大于首峰值6倍;圆筒壁面上的压力载荷最大峰呈现凹型分布规律。该研究结果可为密闭环境内爆载荷的特性分析和结构毁伤评估提供参考。

基于ADAMS的助力型外骨骼特征动作驱动液压缸运动学研究

以助力型外骨骼为研究对象,以建立助力型外骨骼运动学模型以及分析外骨骼运动学特性为研究目标,以运动生物力学为基础,选择单膝下跪-起立动作为特征动作,采用多层次光学捕捉系统采集人体运动数据,采用多波峰(波谷)最小二乘法进行数据拟合,得到人体运动时特征角度的数学模型。助力型外骨骼在完成动作时需要与人体高度偕行,因此将特征角度的数学模型运用到助力型外骨骼中,建立外骨骼三维模型,在ADAMS软件中完成外骨骼特征动作仿真,以此来分析外骨骼运动学特性。

基于时域回归模型的CVT传递特性获取方法

扫频法获取电容式电压互感器(capacitor voltage transformer, CVT)的传递特性时,存在电源功率大、频带受限的难题,因此提出了一种基于时域回归模型的CVT传递特性获取方法,并进行了传递特性曲线的可信度评估。当CVT工作在线性状态时,其传递函数可表示为s域多项式构成的分式形式,进而可建立其时域回归模型。基于单次冲击试验获取CVT一次、二次侧数据,考虑了时域回归模型在实际建模中的多波峰以及鲁棒性问题,提出了基于调幅矩阵和鲁棒矩阵的参数辨识方法。对比扫频法测量所得的传递特性曲线和时域回归模型的传递特性曲线并进行可靠性评估,结果显示误差曲线的均值处于零假设的95%置信区间以内,所提出的传递特性获取方法可为现场快速获取CVT的传递特性提供理论指导。

Short-span interleaving based selected mapping

A novel interleaving based selected mapping （SLM） scheme to depress the relatively high peak power of transmit signals in multicarrier communications is proposed. In the scheme, a group of bit-level interleavers spanning only a few bits are used to produce multiple sequences representing the same information, and one of the sequences resulting in the lowest peak-to-average power ratio （PAPR） is selected for transmission. The implementation of the scheme including the structure of the short-span interleaver is illustrated. The performance of this PAPR reduction scheme is investigated by simulations. This scheme exhibits a good PAPR reduction performance, and for signals of high level modulation, such as 16QAM and 64QAM, it approaches the best performance of all SLM schemes. Compared to the conventional interleaving SLM, this short-span interleaving SLM results in a very short time delay, requires very few register units for buffering, and can be easily implemented by hardware.

Overlapped peaks resolution for linear sweep polarography using Gaussian-like distribution

A resolution method based on Gaussian-like distribution for overlapped linear sweep polarographic peaks was proposed to simultaneously detect the polymetallic components, such as Zn（Ⅱ） and Co（Ⅱ）, coexisting in the leaching solution of zinc hydrometallurgy. A Gaussian-like distribution was constructed as the sub-model of overlapped peaks by analyzing the characteristics of linear sweep polarographic curve. Then, the abscissas of each peak and trough were pinpointed through multi-resolution wavelet decomposition, the curve and its derivative curves were fitted by using nonlinear weighted least squares （NWLS）. Finally, overlapped peaks were resolved into independent sub-peaks based on fitted reconstruction parameters. The experimental results show that the relative error of half-wave potential pinpointed by multi-resolution wavelet decomposition is less than 1% and the accuracy of Ip fitted by NWLS is higher than 96%. The proposed resolution method is effective for overlapped linear sweep polarographic peaks of Zn（Ⅱ） and Co（Ⅱ）.

GRADIENT OF REFERENCE DIFFERENCE BASED MATCHING ALGORITHM FOR IMAGE FEATURE POINT

During matching on feature point, gray correlation matching technology is utilized to extract multi-peaks as a coarse matching set. A pair of given corresponding reference points within the left and right images is used to calculate gradients of reference difference between the reference points and each feature point within the multi-peaks set. The unique correspondence is determined by criterion of minimal gradients of reference difference. The obtained correspondence is taken as a new pair of reference points to update the reference points continuously until all feature points in the left (or right) image being matched with the right (or left) image. The gradients of reference difference can be calculated easily by means of pre-setting a pair of obvious feature points in the left and right images as a pair of corresponding reference points. Besides, the efficiency of matching can be improved greatly by taking the obtained matching point as a new pair of reference points, and by updating the reference point continuously. It is proved that the proposed algorithm is valid and reliable by 3D reconstruction on two pairs of actual natural images with abundant and weak texture, respectively.

华盛江泉酒店音视频系统工程设计分析

应用光缆传输网络和媒体矩阵将扩声系统、舞台机械系统、舞台演艺灯光系统、集中控制系统、远程视频会议系统、同声传译系统、自动摄像会议系统等各子系统集成控制并管理。

Application of wavelet transform in-ray spectra analysis

The frequency distribution of different ingredients in-ray spectra,e.g.,photo-peak,fluctuations of counts and Compton region,is separately analyzed.After wavelet transform of-ray spectra,the wavelet coefficients of a photo-peak increase with transforming scales and these coefficients show direct proportion with intensity of peak at determinate scale.A novel algorithm based on wavelet transform is proposed and studied.The results indicate that most of the photo-peaks in multi-spectra can be determined accurately,the-rays energy and intensity of the peak can also be determined.This method has the prospect of being applied in on-line multi-spectra analysis in such fields as radioprotection and nuclear safety monitoring.