Probabilistic analysis of geomembrane puncture from granular material under liquid pressure

A simplified probabilistic analysis of geomembrane punctures from granular material was presented when subjected to liquid pressure. The probability distribution of contact force between geomembrane and granular material was obtained based on the principle of equal probability and assumptions that grains are spheres with constant size. A particle flow code PFC^3D was employed to simulate the contact process which indicates a good agreement with the theoretical probabilistic analysis. The odds of geomembrane puncture from grains of constant size were obtained by evaluating the puncture force which should not exceed the puncture resistance of geomembrane. The effects of grain radius, grain rigidity and liquid pressure were studied in more detail and displayed in graphs. Both high-level of liquid pressure and large grain can result in high risk of geomembrane puncture. The influence of grain rigidity on the geomembrane puncture odds is significant. For granular material with a grain size distribution, the geomembrane puncture odds can be estimated by the grain size distribution, served as weight function and it is a cautious design if the largest grain is chosen as the design grain size.     

无线信道图像的联合信源信道编码速率分配

分析了信源信道编码速率对图像质量的影响，提出一种联合信源信道编码的速率分配方案。针对渐进图像的速度分配疸建立了数学模型，对模型的求解进行了简化，并采用拉格朗日乘数法，在满足一定的约束条件下实现了速度的最优化分配。在瑞利及Gilbert-Elliot信道下的仿真结果表明，该方案在低信噪比时的性能明显优于固定信道方法，在高信噪比时也较固定信道速率方法有0.2dB左右的性能增益。     

基于IP核的Viterbi译码器实现

Viterbi译码器在通信系统中应用非常普遍,针对采用DSP只能进行相对较低速率的Viterbi译码的问题,人们开始采用FPGA实现高速率Viterbi译码。本文首先简单描述了Viterbi译码的基本过程,接着根据Viterbi译码器IP核的特点,分别详细介绍了并行结构、混合结构和基于混合结构的增信删余3种Viterbi译码器IP核的主要性能和使用方法,并通过应用实例给出了译码器IP核的性能仿真。     

Seldinger技术改良法单人置鞘操作流程的探讨

Seldinger技术是血管内介入性诊疗需涉及的技术,其改良法更具优点,加之器械应用的改进,使得单人置管成为可能。探讨此技术的操作流程有助于在临床顺利开展血管内介入放射治疗术,实践证明此方法不仅简便易行,定位准确,而且置管可靠,少有不良反应及严重损伤。     

用于个体防刺服的UHMWPE纤维针刺毡的性能研究

对UHMWPE(超高分子量聚乙烯)纤维针刺毡单层样品的撕破强力、顶破强力和多层样品的抗刺穿能力进行了测试,结果表明:随着单层UHMWPE纤维针刺毡面密度的增加,试样的顶破强力增大;在20~55℃范围内,随着试样预处理温度升高,顶破强力和抗刺穿能力皆增强,但是试样的撕破强力则无这种变化趋势。     

激光经超声和腹腔镜引导经皮穿刺凝固动物肝脏的实验研究

深入探讨了超声和腹腔镜引导经皮穿刺Nd：YAG激光凝固大和猪及免肝脏的手术方法，得到了最佳激光功率和时间，证实本手术方法简便、安全、易推广，适用于临床治疗肝肿瘤病人。     

Novel system with damage initiated autonomous healing property based on heterogeneous blends of ethylene-methacrylic acid ionomer

Self-healing behavior of ionomer blends containing both rapidly crystallizing phase and with higher amount of amorphous phase has not yet been studied. This work gives a new insight to understand the development of materials with intrinsic self-healing property. In particular, binary blends based on poly(ethylene-co-methacrylic acid sodium salt) (EMNa)/Poly(vinyl alcohol-co-ethylene) (EVA) and epoxidized natural rubber (ENR), were studied by ballistic puncture tests. In the composition range explored (15-50 wt.% of EVA and ENR), the self-healing characteristics decrease with the increasing amount of EVA but are maintained in all ranges for ENR/EMNa blends. The ballistic damage initiated autonomous healing was observed by optical microscopy and the healing was further analyzed by thermal and mechanical behaviors of the blend materials.     

穿刺测试和 fisher 判别法在葡萄贮藏期间质地评价的应用

本实验的目的是利用统计学方法验证所编辑的10个穿刺测试参数在贮藏期间葡萄软化过程中是否有测试意义,是否可以代表葡萄浆果的整体质构特点。同时找出评价贮藏期葡萄质地差异的最关键的质构参数,为贮藏期葡萄质地评价提供理论依据。将意大利、巨峰、白罗莎里奥和马奶4个不同品种的葡萄分别通过冷库模拟冷库贮藏条件,通过恒温恒湿箱模拟运输和货架贮藏条件,得到葡萄浆果穿刺参数在不同贮藏条件下的测量值,并对其进行判别分析。结果表明:在温度高于0℃（运输或货架）贮藏期间葡萄软化过程中所编辑的10个穿刺参数有测试意义,可以区分出葡萄在不同贮藏期的质构变化,也很好的总结了整条力-位移穿刺曲线,可以代表葡萄浆果整体的质构特点。在温度0℃（冷库贮藏）贮藏期间葡萄软化过程中所编辑的10个穿刺参数对葡萄质构的区分度不大,没有实际测试意义。其中,果皮硬度、果皮刚度以及浆果形变度是评价贮藏期质地变化最关键的参数。