Response of the seated human body to whole-body vertical vibration: biodynamic responses to sinusoidal and random vibration

The dependence of biodynamic responses of the seated human body on the frequency, magnitude and waveform of vertical vibration has been studied in 20 males and 20 females. With sinusoidal vibration (13 frequencies from 1 to 16 Hz) at five magnitudes (0.1–1.6 ms^? 2 r.m.s.) and with random vibration (1–16 Hz) at the same magnitudes, the apparent mass of the body was similar with random and sinusoidal vibration of the same overall magnitude. With increasing magnitude of vibration, the stiffness and damping of a model fitted to the apparent mass reduced and the resonance frequency decreased (from 6.5 to 4.5 Hz). Male and female subjects had similar apparent mass (after adjusting for subject weight) and a similar principal resonance frequency with both random and sinusoidal vibration. The change in biodynamic response with increasing vibration magnitude depends on the frequency of the vibration excitation, but is similar with sinusoidal and random excitation.     

Response of the seated human body to whole-body vertical vibration: discomfort caused by sinusoidal vibration

Frequency weightings for predicting vibration discomfort assume the same frequency-dependence at all magnitudes of vibration, whereas biodynamic studies show that the frequency-dependence of the human body depends on the magnitude of vibration. This study investigated how the frequency-dependence of vibration discomfort depends on the acceleration and the force at the subject–seat interface. Using magnitude estimation, 20 males and 20 females judged their discomfort caused by sinusoidal vertical acceleration at 13 frequencies (1–16 Hz) at magnitudes from 0.1 to 4.0 ms^? 2 r.m.s. The frequency-dependence of their equivalent comfort contours depended on the magnitude of vibration, but was less dependent on the magnitude of dynamic force than the magnitude of acceleration, consistent with the biodynamic non-linearity of the body causing some of the magnitude-dependence of equivalent comfort contours. There were significant associations between the biodynamic responses and subjective responses at all frequencies in the range 1–16 Hz.

Practitioner Summary: Vertical seat vibration causes discomfort in many forms of transport. This study provides the frequency-dependence of vibration discomfort over a range of vibration magnitudes and shows how the frequency weightings in the current standards can be improved.     

Face detection by structural models

Despite the successes in the last two decades, the state-of-the-art face detectors still have problems in dealing with images in the wild due to large appearance variations. Instead of leaving appearance variations directly to statistical learning algorithms, we propose a hierarchical part based structural model to explicitly capture them. The model enables part subtype option to handle local appearance variations such as closed and open month, and part deformation to capture the global appearance variations such as pose and expression. In detection, candidate window is fitted to the structural model to infer the part location and part subtype, and detection score is then computed based on the fitted configuration. In this way, the influence of appearance variation is reduced. Besides the face model, we exploit the co-occurrence between face and body, which helps to handle large variations, such as heavy occlusions, to further boost the face detection performance. We present a phrase based representation for body detection, and propose a structural context model to jointly encode the outputs of face detector and body detector. Benefit from the rich structural face and body information, as well as the discriminative structural learning algorithm, our method achieves state-of-the-art performance on FDDB, AFW and a self-annotated dataset, under wide comparisons with commercial and academic methods.     

Cu2O/Cu Cermet as a Candidate Inert Anode for Al Production

Cu₂O/ x Cu ( x =0–25 wt%) cermets were evaluated as a novel partially inert anode for aluminum (Al) production. The physical and mechanical properties, including the compressive strength, flexural strength, thermal expansion coefficient, thermal conductivity, and dc electrical conductivity were tested at room temperature and at temperatures up to 950°C. The coefficient of thermal expansion, compressive strength, flexural strength, thermal conductivity, and electrical conductivity of Cu₂O/Cu cermets increased with increasing Cu content. High-temperature electrical conductivity measurements showed that with increasing temperature, the electrical conductivity increased when the Cu content was below the percolation threshold, while it decreased when the Cu content was above the percolation threshold. A relatively stable CuAlO₂ layer formed on the cermet surface during electrochemical testing, and the corrosion rate of this anode was estimated to be about 1.8–1.9 cm/year in Al production.     

超磁致伸缩作动器的率相关Hammerstein模型与H∞鲁棒跟踪控制

利用Hammerstein模型对超磁致伸缩作动器（Giant magnetostrictive actuators,GMA）的率相关迟滞非线性进行建模,分别以改进的 Prandtl-Ishlinskii（Modified Prandtl-Ishlinskii）模型和外因输入自回归模型（Autoregressive model with exogenous input,ARX）代表Hammerstein模型中的静态非线性部分和线性动态部分,并给出了模型的辨识方法. 此模型能在1～100Hz频率范围内较好地描述GMA的率相关迟滞非线性. 提出了带有逆补偿器和H∞鲁棒控制器的二自由度跟踪控制策略,实时跟踪控制实验结果证明了所提策略的有效性.     

Exponential synchronization of two totally different chaotic systems based on a unified model

This paper presents an exponential synchronization scheme between two chaotic systems with different structures and parameters. A unified model consisting of a linear dynamic system and a bounded static nonlinear operator is employed to describe these totally different chaotic systems. A novel state feedback control law is established to exponentially synchronize the two unified models with different parameters. Most chaotic systems with different structures and parameters, such as Hopfield neural networks, cellular neural networks, Chua’s circuits, unified chaotic systems, Qi systems, and chaotic recurrent multilayer perceptrons, can be transformed into this unified model with the synchronization controller designed in a unified way. Two numerical examples are exploited to illustrate the effectiveness of the proposed design schemes.     

基于回归模型的CPU超频仿真软件设计

为了帮助认识CPU超频问题并熟悉超频设置操作,进行CPU超频仿真软件设计的全面研究。分析CPU超频的影响因素,介绍超频的方法和操作流程;讨论软件的功能模块结构、模块的运行流程和样本数据的存储方法;重点研究CPU超频后的性能测试结果估计问题,并为此提出了建立回归模型的解决之道;详细探讨了VB.NET与Matlab混合编程的接口与实现途径,并以此种方式完成了程序代码的编写。试用表明,该软件功能完整、界面直观、使用简便,能够为理解超频理论和熟悉超频操作提供有效帮助。     

基于表面等离子体共振传感器的尿微量白蛋白检测

检测尿微量白蛋白(MAU)可对轻微肾脏损害进行早期诊断,也可对高血压患者可能发生的心脑血管事件进行预测。实验将抗体通过巯基自组装固定于Au膜表面,研制了一种快速检测MAU的表面等离子体共振(SPR)生物传感器。结果表明:直接检测法可以检测到0.3μg/L的MAU,而纳米Au放大法检测限可以低至0.03μg/L。     

用于光刻系统仿真的多边形处理算法

为提高光刻仿真效率,通过对光刻原理进行研究,提出了2种多边形处理算法,将掩模上的多边形图案进行切分优化,将其划分成若干矩形或三角形。在Linux环境下应用C语言设计出一个完整的光刻仿真系统,设计的具体光学参数为:光源波长为193nm,数值孔径为0.3~0.8,部分相干系数可调范围为0.2~0.8,可一次性仿真1μm×1μm到10μm×10μm范围内的45 nm~0.18μm工艺的复杂版图,并通过多次实验进行验证。实验结果表明:原版图图像的边缘细节得到保留,且该算法有效地减少了光刻模拟的计算复杂度与计算时间,整体效率提升20%以上,为当前智能传感器系统芯片的制造节省了宝贵时间。     

具有谐波减速器的柔性关节参数辨识

为了辨识具有谐波减速器的柔性关节模型的关键参数,设计了一套基于多传感器融合的离线辨识方法,根据电机的位置传感器、电流传感器和关节力矩传感器的实验数据完成柔性关节模型关键参数的辨识.首先,建立采用谐波减速器柔轮输出的柔性关节模型;然后,使用正反转加载力矩的方法辨识出电机的力矩系数;并在空载的情况下,由关节力矩和电机输出力矩分别辨识出关节端和电机端的摩擦力;最后,采用敲击法初步辨识出关节的刚度和阻尼后,在关节位置受限条件下,逐渐增加电机输出力矩,得到柔性关节刚度和关节力矩的非线性关系.多次实验的结果显示,辨识出的参数具有较高的重复性,验证了该方法的有效性.