摘要：For cone beam computed tomography(CBCT),there has long been a desire to modulate the intensity and distribution of the X-rays to accommodate the patient’s anatomy as the gantry rotates from one projection to *** would reduce both image artifacts and radiation ***,the current beam modulation setups,such as dynamic bowtie filters,may be too complex for practical use in clinical *** study aimed to investigate a simplified dynamic beam filtration strategy for CBCT imaging to reduce image artifacts and radiation *** this study,the beam filtration was designed to vary dynamically as the CBCT gantry rotates around the ***,two distinct components were integrated:the sheet filter part and the bowtie filter *** dynamic beam filtration setup has two working schemes,one is a combination of dynamic sheet filter and dynamic bowtie filter,denoted as dynamic filterdynamic bowtie(DFDB);the other is a combination of dynamic sheet filter and static bowtie filter,denoted as dynamic filter-static bowtie(DFSB).Numerical imaging experiments were performed for three human body parts:the shoulder,chest,and *** addition,the Monte Carlo simulation platform MC-GPU was used to generate the dose distribution *** showed that the proposed DFDB and DFSB beam filtration schemes can significantly reduce the image artifacts and thus improve the CBCT image *** on the scanned object,the total radiation dose could be reduced by 30%.The proposed simple dynamic beam filtration strategy,especially the DFSB approach,could be beneficial in the future to improve the CBCT image quality with reduced image artifacts and radiation dose.

摘要：树形双边贯通供电方案能够取消牵引变电所出口和分区所处的电分相,提高系统的供电能力和再生制动能量利用率。介绍了树形双边供电方案的构造;针对树形双边贯通供电方案,以复线直接供电方式为例,推导了牵引网双边供电区间在复线牵引网上下行不并联、末端并联、全并联,以及端头供电臂单边供电等情况下的牵引网阻抗模型;以牵引变电所为单元,构建了树形双边贯通供电系统的全线链式电路模型,给出了潮流迭代方法;将树形双边贯通供电方案应用于某重载铁路贯通供电改造,对既有供电方案和树形双边贯通供电方案的牵引网等值阻抗和方案设计等进行了仿真及对比分析。仿真结果表明,相较于既有方案,树形双边贯通供电方案能够减小牵引网阻抗,提高供电能力,再生制动能量利用率提高至100%,每年通过利用再生制动能量节省的电费约为460.58万元。

摘要：在分析射频识别原理和特点的基础上,讨论超高频射频识别系统中电子标签设计技术,并采用EP1C6Q240FPGA对超高频电子标签进行了板级设计及其实现。利用Verilog语言实现了标签数字电路,并在板级标签中进行了验证。测试结果表明,该设计实现了ISO18000-6C标准的标签读写功能,读写性能优异,为下一步设计出符合该标准的电子标签芯片提供了有力保证。

摘要：通过静力加载试验及ABAQUS非线性有限元分析来研究T形钢管混凝土组合柱-钢筋混凝土梁外伸端板连接节点力学性能。结果表明:节点剪力主要由核心区形成的斜压杆来承担,而牛腿腹板承担的比例较小;设置加劲肋可有效抑制端板翘曲变形,缓解节点区应力集中,比增加端板厚度更能有效提高节点抗弯承载力;轴压比小于0.4时,增大轴压比节点抗弯承载力略有提高,轴压比大于0.4时,增大轴压比节点抗弯承载力稍有降低,但提高、降低的幅值均很小;梁柱线刚度比对节点抗弯承载力影响较小;提高框架梁混凝土强度等级,节点抗弯承载力相应有所提高;提高框架梁配筋率,节点抗弯承载力明显增大,但当配筋率超过1.8%后继续提高时,节点抗弯承载力提高的幅值较小;有限元计算骨架曲线与试验结果能较好吻合,验证了有限元模型的合理性。

摘要：将高压CO 2与切削加工相结合,能显著改善难加工材料加工性能,是类新兴的绿色加工技术,其工艺装备亟待开发。基于TRIZ理论,使用物质-场分析、冲突理论,裁减、效应等工具,并结合资源分析、小人法与金鱼法,从高压CO_(2)冷却润滑工艺开发与装置设计角度出发,形成了高压分级利用、自冷缓冲罐工艺与装置、内冷车刀、切削力调控等解决方案。总体上提升了冷却润滑效能,并减少能耗与成本。经综合评估形成解决方案,整合并形成多项专利。该研究对CO 2冷却加工技术开发、实施,以及机械装置的创新设计和优化具有一定的参考意义。