引江济淮工程江淮沟通段杨大庄跌水三维数值模拟研究

为解决引江济淮跌水、跌井汇流口水流水力特性模拟问题,采用基于 VOF 法的 RNG k-ε 双方程紊流数学模型对杨大庄跌水工程进行三维数值模拟研究,通过计算结果与已经完成的水工模型试验结果相对比,验证该模型模拟杨大庄跌水工程水流的水力特性的可行性。 研究结果表明：通过合理的处理网格及计算参数,杨大庄跌水水流入渠的流态、流速分布及水位数值模拟结果整体与试验值吻合较好,说明利用该模型模拟杨大庄跌水工程水流的水力特性是可行的,数学模型可用于指导和解决类似工程问题。     

基于小波变换的血压信号特征提取方法研究

该文针对传统的人体血压信号特征提取方法的不足,提出了一种了基于小波变换的人体血压信号特征量提取方法。人体的血压信号是一种非平稳的低频信号,使用Marr小波对人体血压信号进行小波变换的时间一尺度分解,可以得到人体血压信号的模极大值曲线;通过选择合适的分解尺度,可以有效地滤除噪声,对人体血压数据进行消噪处理;进一步滤除奇异性极大值点,可以提取出动脉波动位置和动脉波动幅度信息。文中给出了算法的完整实现,并利用实际采集的人体血压数据验证了该算法,得到了波峰模极大值点和心脏跳动所发生的精确时刻,为人体血压信号的参数识别奠定了基础。     

体内微型机器人的全方位旋进驱动特性

提出了一种由外旋转磁场驱动的体内微机器人．它以相邻径向异向磁化瓦状多磁极圆筒形NdFeB永磁体为外驱动器,以机器人内嵌同结构的NdFeB永磁体为内驱动器,外驱动器旋转时产生旋转磁场,通过磁机耦合作用于内嵌驱动器形成机器人驱动力矩,在本体外表面螺纹与流体动压力的作用下,实现机器人在管道内的在线旋进．在建立微机器人游动模型的基础上,以垂直管道为试验环境,研究了机器人的全方位驱动特性,试验结果表明机器人可以实现管道内全方位驱动．     

Improvement of the electrical resistivity of epoxy resin at elevated temperature by adding a positive temperature coefficient BaTiO_3-based compound

The DC electrical resistivity-temperature characteristic is an important property for insulating materials to operate at a high stress level. In order to improve the DC electrical resistivity at elevated temperature in a targeted way, a positive temperature coefficient(PTC) material(Ba Ti O3-based compound(BT60)) was selected as the filler in this paper, whose electrical resistivity has a PTC effect when the temperature exceeds its Curie temperature. The BT60 was treated with hydrogen peroxide and(3-Aminopropyl) triethoxysilane. Epoxy composites with different loadings of BT60 fillers(0 wt%, 0.5 wt%, and 2 wt% of epoxy) were prepared, denoted as EP-0, EP-0.5, and EP-2. It was shown that BT60 was able to maintain the DC breakdown strength when its loading was less than 2 wt% of epoxy. As the temperature exceeds 60 °C,BT60 will compensate for the negative temperature coefficient effect of epoxy resin to some extent. The electrical resistivity of EP-2 was improved by 55% compared with that of neat epoxy at 90 °C. It was found that the potential barrier at the grain boundary of BT60 and the deep traps in the interface between BT60 and the epoxy resin hinder the migration of carriers and thus increase the electrical resistivity of epoxy composite.     

Optimized analysis of sharpening characteristics of a compact RF pulse source based on a gyro-magnetic nonlinear transmission line for ultrawideband electromagnetic pulse application

We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line (GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate, which shows great potential for application in the high-power ultrawideband electromagnetic effect, etc. The influence of incident pulse parameters (rise time and voltage amplitude) and line length on the sharpening characteristics of the GNLTL were investigated experimentally to optimize the rising rate of the modulated pulse front. Based on the GNLTL equivalent circuit model consisting of an LC ladder network, the rise time, the voltage conversion coefficient and the rising rate properties of a modulated pulse were also numerically analyzed in a wider range. The results show that a>90 kV RF pulse with a rise time of 350 ps and a repetition rate of 1 kHz in burst mode is produced by the GNLTL at an axial biasing magnetic field of 22 kA m⁻¹ and a line length of 30 cm under the condition of a 70 kV incident pulse. Applying a faster and higher incident pulse is conducive to improving the sharpening effect of the GNLTL. Furthermore, within a certain range, increasing the line length of the GNLTL not only reduces the rise time, but increases the voltage conversion coefficient and the rising rate of a modulated pulse. Furthermore, considering the energy loss of ferrite rings, there is an optimal line length to obtain the fastest rising rate of a modulated pulse front edge.     

轧机两侧刚度差的数字化分析与改善措施

轧机两侧刚度差是轧机功能精度的最重要指标之一,以弹跳方程为基础定量计算了轧机两侧刚度差对轧制稳定性的影响,主要包括调平值、调平值随轧制力的变化以及甩尾3个方面。以此为基础在某热轧线建立了轧机刚度评价体系,对轧机功能精度进行管控。同时,还分析了轧机两侧刚度差的影响因素,并在定量分析的基础上采取了一系列的改善措施,包括衬板、垫片维护、最大压靠轧制力和标定轧制力的调整等,使轧机刚度和轧制稳定性得到大幅提升。     

小官庄铁矿矿床地质特征分析

叙述了鲁中冶金矿业集团公司小官庄铁矿矿床的地质概况及特征、矿体特征、找矿标志和矿床成因.     

四流T型中间包钢液流场的数学物理模拟

应用商业软件PHOENICS及水力学模型,对某厂四流中间包钢液流场进行了模拟研究,讨论了导流墙、导流孔及湍流抑制器对钢液流场的影响.通过模型研究为中间包内控流装置的结构优化提供了理论依据.     

涡轮桨搅拌槽内流动特性的大涡模拟

利用大涡模拟方法研究了涡轮桨搅拌槽内的流动特性,采用了三种亚格子模式:标准Smagorinsky-Lilly模式(SLM)、Smagorinsky-Lilly动力模式(DSLM)和亚格子动能动力模式(DKEM),并将模拟结果与标准k-ε模型及文献实验数据进行了详细的比较.结果表明:大涡模拟方法可获得搅拌槽内的瞬态流场;对桨叶区时均速度及湍流动能的预测与实验数据相吻合,比标准k-ε模型计算结果有明显改进,三种亚格子模型中DSLM和DKEM模拟结果更好.同时分析了大涡模拟中桨叶端部附近湍流动能估计偏差的原因,发现主要是由于对轴向湍流均方根速度的预测偏差造成的.大涡模拟方法为搅拌槽内非稳态、周期性的湍流流动和湍流特性的研究提供了强有力的工具.     

隧道洞口上方危岩崩塌块石运动规律及其对隧道的危害

为揭示危岩崩塌块石的运动规律及其对下方隧道洞口的危害,以都香高速昭通段乐红隧道洞口高陡边坡危岩区崩塌体为研究对象,运用理论计算与Rockfall数值计算2种形式对危岩区崩塌体失稳后块石的运动特征进行预测,运用Abaqus有限元软件模拟不同初速度、不同冲击落点下块石冲击隧道结构的动力响应,揭示不同因素对块石冲击隧道结构的...