非充气安全轮胎的研究现状

随着车辆行业的不断发展,充气橡胶轮胎爆胎引发的交通事故率越来越高。为了降低爆胎的发生率,世界各大轮胎公司推出了一系列安全性能优异的非充气安全轮胎,本文针对这些非充气安全轮胎的研究现状进行了介绍,为国内非充气安全轮胎的研发及轮胎结构设计提供一定的参考建议。     

耐压击穿装置的容量问题

根据影响介质击穿的主要因素,本文着重阐述了交流耐压击穿装置的容量指标问题.在确定耐压击穿装置的容量时,不仅要考虑到被试样件两极间的等效电容值,同时还要估计到试件在击穿过程可能产生的最大击穿电流值.对于某种绝缘材料或构件,合理选用耐压击穿装置的容量对正确进行试验是很重要的.     

Geomembrane puncture and strains from stones in an underlying clay layer

Results from physical experiments are presented to assess the possible puncture of a 1.5-mm-thick HDPE geomembrane and, if not punctured, the maximum tensile strains in the deformed geomembrane from intentionally placed stone particles in an underlying compacted clay liner when subjected to applied vertical stresses. The influences of applied pressure, clay water content, stone size, stone burial depth and protection layer on the geomembrane tensile strains are reported. Except in one test conducted to a pressure of 2000 kPa, the geomembrane was not punctured in the short-term tests conducted; however, it was subjected to local indentations and tensile strains from the underlying gravel particles that may exceed proposed allowable long-term strain limits. Tensile strains for the specific 35 mm stones tested when initially flush with the clay surface were negligible, even up to pressures of 1000 kPa, provided the initial water content of clay was 12%. Increases in water content or stone size were found to increase the tensile strain. Placing the clay at the lower limit of acceptable water content was found to be beneficial in terms of reducing strains from buried stones; however, this was also found to make the geomembrane more susceptible to stone particles sitting on top of the clay surface and hence careful site inspection is required to remove all visible stones that sit on top of the clay surface.     

不同组织结构涤纶织物的刺破实验分析及破坏形态

本文研究了平纹、2/2斜纹、双轴向经编和紧密型四种不同组织结构的涤纶织物的刺破性能。通过在MTS-810材料试验机上进行破坏性实验,用刺锥分别刺破不同组织结构的四种涤纶织物,得到织物在刺破过程中的载荷—位移曲线并分析讨论,比较实验后的织物破坏形态,从而得到不同的织物组织结构对织物刺破性能的影响。最后,预测不同组织结构涤纶织物作为预成型结构件,制成复合材料的刺破性能。     

IEEE802.16d下一种改进的打孔卷积编码算法及FPGA实现

分析了信道编码在正交频分复用（OFDM）系统中的作用,重点研究了卷积编码原理和具体实现。参考IEEE802.16d标准,结合现有多码速率编码算法,提出了一种新的打孔算法,仿真实验表明该算法降低了系统的误码率;可编程逻辑器件（FPGA）上的硬件在线调试表明实测结果和算法仿真结果吻合,且在提高可靠性的同时,节省了硬件资源。     

Puncture resistance of polyester (PET) and polypropylene (PP) needle-punched nonwoven geotextiles

It is common practice to use needle-punched nonwoven geotextiles as puncture protection for geomembranes against sharp objects like gravel or stones in either the soil above or the underlying soil/rock below. There are several design and experimental methods available for geotextile selection in this regard. None, however, directly address the type of resin or fiber from which the geotextile is made. This paper does exactly that insofar as a direct comparison of similar mass per unit area polyester (PET) versus polypropylene (PP) geotextiles are concerned. Furthermore, two types of PP geotextiles are evaluated; one made from continuous filaments and the other from staple fibers. Three different size and shaped puncture probes are used in the testing program. All three are ASTM Standards, i.e., D4833, D5495 and D6241.The test results clearly indicate that geotextiles made from PP fibers outperform those made from PET fibers at all masses evaluated. Clearly, the present trend of using PP resin for heavy nonwoven protection geotextiles seems justified on the basis of these test results. In addition, the continuous filament PP and staple fiber PP geotextiles performed equivalently over all mass ranges for the three different types of puncture tests.     

穿刺翻边的裂口缺陷

结合两个实例介绍了穿刺翻边裂口的形成过程,分析了产生裂口的原因,提出了解决裂口问题的措施。     

Healing DNA Self-Assemblies Using Punctures

In self-assembly, individual components (commonly referred to as tiles) have sufficient infor mation to build templates for structures such as lat tices for two-dimensional scaffolds. Tile sets that can heal (fully or partially) an erroneous DNA assembly have been proposed. Healing requires growth to be restarted such that erroneous tiles can be removed and the correct tiles can bind to the aggregate. Punctures have been proposed for this purpose; in this paper, a puncture is intentionally induced in the self-assembly to restart the growth process. The goal of this paper is to characterize an intentionally induced puncture (and its relevant properties) on an erroneous tile site in the grown crystal as part of a healing process. This allows to propagate any newly generated error away from the source of growth (i.e. the seed tile), such that self-assembly can continue along specific directions. Different types of puncture are considered with respect to healing and related features, such as growth direction, error and aggregate types. Punctures are analyzed using a new characterization and metric; different tile sets are investigated in detail for healing of a DNA self-assembly.

Microscale investigation into mechanical behaviors of heat-bonded nonwoven geotextile using DEM

Heat-bonded nonwoven geotextiles (HBNGs) made from synthetic fibers are widely used in engineering practices. One of the challenges on the way is to link the properties of fibers and the fabric's microstructure to the deformation and failure mechanisms of HBNGs. In this study, a random distribution geometry method was developed to reproduce the complex fibrous structure of HBNG. A piecewise linear model was adopted to reproduce the nonlinear stress-strain relationships of single fibers. The present method has been successfully applied in the simulation of uniaxial and biaxial tensile tests and puncture test. The orientation distribution of fibers and the mechanical behaviors (e.g., deformation, strain localization, force-strain relationship) of HBNG specimen were reasonably simulated. Specifically, the hourglass shape during uniaxial tensile test, the axisymmetric deformation pattern during biaxial tensile test and the trumpet shape during puncture test were all well reproduced. The present method provides an applicable tool to study the complicated mechanical behaviors of HBNG and is also helpful to obtain a better understanding of its deformation and failure mechanisms.     

基于超声图像的PICC智能穿刺医疗机器人控制系统设计

为提高静脉穿刺置管手术的穿刺成功率,缓解病人所承担的生理性伤痛,设计基于超声图像的PICC（Peripheraly Inserted Central Cathcte,外周静脉置入的中心静脉导管）智能穿刺医疗机器人控制系统。以晶振复位电路作为穿刺置管的输出动力支持,通过驱动控制电机的传输调度作用,实现对智能传感器的精准化控制,降低置管过程中针头的平均进入深度,完成PICC智能穿刺医疗机器人及其控制应用结构搭建。在此基础上,按照静脉置管图像的实际特征分析结果,转换原有的超声图像格式,经过多次边缘性检测,实现对穿刺超声图像的初级预处理。获取静脉靶向血管的位置信息,在规划穿刺路径的同时,完成对机器人操作手的重定位控制,实现医疗机器人的运动控制模型分析。仿真对比实验结果显示,与常规静脉穿刺手段相比,穿刺控制系统可将进针角数值控制在10°-40°之间、进针深度保持在整个针头的2/3以内,可大幅提升穿刺置管的成功几率,实现减轻病人所承担生理性疼痛的目的。