一种电阻加载的L型谐振器及其在微带均衡器中的应用研究

文章提出了一种薄膜电阻加载的L型谐振器,设计了一种小尺寸的微带均衡器子结构电路,并对薄膜电阻的加载位置进行了研究。分析表明这种电阻加载的L型谐振器不仅能够进行中心频率调节、曲线衰减幅度调节,而且能够对谐振回路的品质因数进行调节,适合在微带均衡器中应用。为微带均衡器的设计提供了一种新的设计途径。     

化工原理计算机试题库系统的初步设计

本文介绍利用正交设计思想，在ＦＯＸＢＡＳＥ２．０（及以上版）系统支持下，研制的基本符合实际考试要求的计算机辅助教学软件－化工原理试题库系统。     

Comparison of OWAS,RULA and REBA for assessing potential work-related musculoskeletal disorders

This study compared three representative observational methods for assessing musculoskeletal loadings: Ovako Working Posture Analysis System (OWAS), Rapid Upper Limb Assessment (RULA), and Rapid Entire Body Assessment (REBA). The comparison was based on 209 cases of upper-body musculoskeletal disorders (MSDs) diagnosed by medical doctors. The most awkward/stressful posture in each participant's tasks was assessed using these techniques. Postural loadings were rated more highly by the RULA than by the OWAS and REBA (p < 0.01). The chi-square test and logistic regression analysis showed that only RULA grand score and action level, and REBA action level were associated with MSD work-relatedness (p < 0.01, p < 0.05, and p < 0.05, respectively). The percentage concordant values of the logistic model for the RULA grand score and action level were 52.4% and 44.8%, respectively, while the percentage concordant value for the REBA action level was 22.1%. Therefore, the RULA may be the best system for estimating the postural loads and work-relatedness of MSDs.Relevance to industryWork-related musculoskeletal disorders are the leading cause of workplace disability in the developed countries. For preventing the disorders, quantification of musculoskeletal loads is required.     

Influence of tyre pressure and vertical load on coefficient of rolling resistance and simulated cycling performance

The coefficient of rolling resistance (C _r) for pneumatic tyres is dependent on hysteresis loss from tyre deformation which is affected by the vertical force applied to the tyres (F _v) and the tyre inflation pressure (P _r). The purpose of this paper was to determine the relative influence of five different levels of P _r and four different levels of F _v on C _r and to examine the relationships of C _r with P _r and F _v during cycling locomotion. F _v was modified through carriage of additional mass by the subject. C _r was determined with the coasting deceleration method from measurements performed in a level hallway. Iterations minimizing the sum of the squared difference between the actual deceleration distance and a predicted deceleration distance were used to determine C _r. This latter distance was computed from a derivation based on Newton's second law applied to the forces opposing motion. C _r was described by a hyperbolic function of P _r (C _r = 0.1071 P _r ^?0.477, r ² = 0.99, p &lt; 0.05), decreasing 62.4% from 150 kPa (C_r= 0.0101) to 1200 kPa (C_r = 0.0038). F _v was related to C _r by a polynomial function (C _r = 1.92.10^?8 F _v ² ?2.86.10^?5 F _v + 0.0142, r ² = 0.99, p = 0.084), with an added mass of 15 kg (C _r = 0.0040) resulting in an 11.4% increase in C _r compared with no added mass (C _r = 0.0035). From this study, it is concluded that the relationships of P _r and F _v with C _r for cycling are non-linear. Furthermore, a simulation model shows that changes in P _r and F _v of the magnitude examined here have an important effect on competitive cycling performance.     

Assessment of an EMG-based method for continuous estimates of low back compression during asymmetrical occupational tasks

Variables, such as peak and accumulated moments and spine compression forces, have been shown to be risk factors for occupational low back pain. Estimates of these forces during prolonged, dynamic, asymmetric tasks using biomechanical models is complex and time-consuming. A simple technique for continuous measurement of these variables over a prolonged period is needed to measure the distribution of spinal loading during both sagittal plane lifts and complex asymmetrical jobs. The aim of this study was to determine whether a linear normalization of erector spinae EMG to spine compression force, called compression normalized EMG (CNEMG), could be used to estimate spinal loading for simulations of asymmetrical occupational tasks. The estimates of spine compression force obtained using the normalized EMG are presented in the form of an amplitude probability distribution function and are compared with estimates of a three-dimensional biomechanical model. The per cent time a worker spends above particular levels of spinal loading of interest, such as the NIOSH action limit for compression, are displayed. Five males performed simulated occupational tasks. The exposure time at a specific level of spine compression force for a combination of three tasks, estimated by CNEMG, was, on average, within 6.5% of the time calculated by the biomechanical model. However, if the task combination was dominated by an axial twisting moment, then the difference was, on average, 13.4%. The difference in magnitude of spine compression at a specific probability was, on average, 14.9% and when axial trunk twist dominated, 30.7%. It is concluded that CNEMG can estimate probability at a specific level of spine compression force when the task combination is characterized by a predominant extensor moment in the sagittal plane. Estimates of spine compression at a specific probability, and estimates obtained during task combinations dominated by an axial twisting moment, are poor.     

基于现场总线的硅片自动装卸控制系统设计

开发了一种基于现场总线的硅片自动装卸控制系统。系统采用PROFIBUS-DP总线和ASI总线相结合的控制方式,实现了PECVD石墨舟硅片的装卸过程自动化,提高了太阳能电池片生产线的生产效率和自动化水平,降低了劳动强度,提高了产品质量。     

高阶系统次优控制集结设计方法

针对现有集结降阶方法计算量大，或者不能保证精确集结，本文给出一种新的精确集结降阶算法，提出一种基于精确集结模型，设计高阶系统的低阶次优线性调节器和集结状态降维观测器的方法。     

基于OpenGL的军用物资装载仿真系统研究

提出了以VisualC++为开发工具,基于OpenGL技术,开发军用物资装载仿真系统的具体方案。采用数值仿真与可视化技术相结合的方法,建立了军用物资装载模型,对物资装载量与装载方式进行仿真,并得出直观的计算结果,为实际货运装载提供理论依据。     

火箭炮装填训练视景仿真系统的设计与实现

箭炮装填训练是炮兵(火箭炮)部队训练的重要内容.根据炮兵实装训练噪声大、费用高等实际情况,提出了火箭炮装填训练混合仿真系统的总体设计,系统由实物仿真子系统和视景仿真子系统组成.着重介绍了视景仿真子系统的开发过程.利用三维建模软件Multigen Creator采用实时仿真不可缺少的DOF(Degrees of Freedom)技术建立了火箭炮、装填车等几何模型,然后利用Lynx的图形用户界面通过引入建立的几何模型生成运动模型,最后运用MFC通过调用驱动软件Vega函数库来生成实时应用程序.建立的三维模型形象逼真,生成的仿真系统经教学试用效果较好.     

可证明安全的需求装载代码协议

主动网络是一种新型的网络,在一些领域已得到初步应用。主动网络中的需求装载代码协议是基于移动代码,装载需求和缓存技术的代码分配协议,可动态配置新的协议和服务。由于已有需求装载代码协议存在被重放的安全缺陷,影响主动节点的性能和效率,为此提出了一个安全有效的改进协议,利用Hash函数的单向性,协议双方无需对报文解密就可判断重放攻击,增强了其抵抗重放攻击的能力,并进行了安全性和计算复杂度分析。