摘要：As one of the core components of turbocharger or micro-turbine, radial turbine has the features of small size and high rotation speed. In order to explore the design method and flow mechanism of the turbine with a volute, a centimeter-scale radial turbine with a vaneless air-inlet volute was designed and simulated numerically to investigate the characteristics of the coupled flow field. The results show that the wheel efficiency of single passage computation without the volute is 80.1%. After accounting for the factors of the loss caused by the volute and the interaction between each passage, the performance is more accurate according to the whole flow passage computation with the volute. High load region gathers at the mid-span and the efficiency declines to 76.6%. The performance of the volute whose structure angle of the trapezoid section is equal to 70 degree is better. Unlike uniform inlet condition in single passage, more appropriate inlet flow for the impeller is provided by the rectification effect of the volute in full passage calculation. Flow parameters are distributed more evenly along the blade span and are generally consistent between each passage at the outlet of the turbine.

摘要：随着航空硬件设计复杂度的提高,芯片验证技术已经成为了芯片设计的难点。为了有效缩短设计流程的总体工作时间,有必要在占据设计大量时间的验证中,研究出快速寻找设计错误的方法。被测设计是兼容ARM V4指令集架构(instruction set architecture,ISA)的处理器模型ARMChisel,该处理器模型采用新型的硬件语言Chisel构建,是一个具有高复杂性的硬件设计。基于这一嵌入式处理器模型:①设计了支持ARM V4 ISA架构全部指令的随机指令生成器,提高了生成测试激励的速度;②根据新型构建语言Chisel的特点,针对被测处理器模型设计了Chisel层面初级验证、覆盖率快速验证、直接测试验证和复杂应用程序验证策略,确保达到预期的覆盖率;③在Chisel环境和Verilog环境中搭建了基于嵌入式处理器模型的测试平台,测试平台收集覆盖率同时能快速准确地发现错误并定位错误,提高了验证速度。采用FPGA(field programmable gute array)方法加速大型应用程序的验证,缩短了验证周期。

摘要：Tillage practices can potentially affect soil organic carbon （SOC） accumulation in agricultural soils. A 4-year experiment was conducted to identify the influence of tillage practices on SOC sequestration in a double-cropped rice （Oryza sativa L.） field in Hunan Province of China. Three tillage treatments, no-till （NT）, conventional plow tillage （PT）, and rotary tillage （RT）, were laid in a randomized complete block design. Concentrations of SOC and bulk density （BD） of the 0-80 cm soil layer were measured, and SOC stocks of the 0-20 and 0-80 cm soil layers were calculated on an equivalent soil mass （ESM） basis and fixed depth （FD） basis. Soil carbon budget （SCB） under different tillage systems were assessed on the basis of emissions of methane （CH4） and CO2 and the amount of carbon （C） removed by the rice harvest. After four years of experiment, the NT treatment sequestrated more SOC than the other treatments. The SOC stocks in the 0-80 cm layer under NT （on an ESM basis） was as high as 129.32 Mg C ha-1, significantly higher than those under PT and RT （P 〈 0.05）. The order of SOC stocks in the 0-80 cm soil layer was NT 〉 PT 〉 RT, and the same order was observed for SCB; however, in the 0-20 cm soil layer, the RT treatment had a higher SOC stock than the PT treatment. Therefore, when comparing SOC stocks, only considering the top 20 cm of soil would lead to an incomplete evaluation for the tillage-induced effects on SOC stocks and SOC sequestrated in the subsoil layers should also be taken into consideration. The estimation of SOC stocks using the ESM instead of FD method would better reflect the actual changes in SOC stocks in the paddy filed, as the FD method amplified the tillage effects on SOC stocks. This study also indicated that NT plus straw retention on the soil surface was a viable option to increase SOC stocks in paddy soils.

摘要：CW型原表面换热器作为可应用于微型涡轮动力装置的一种换热器型式,目前还没有公认的设计准则。代理模型优化设计是一种效率高、应用广泛的设计方法,本文引入该方法开展原表面换热器的设计工作。本文采用拉丁超立方试验设计方法在设计空间进行取样,结合Kriging代理模型与多目标优化遗传算法NSGA-Ⅱ进行优化设计。经验证,最终得到的原表面换热器效能可达到86.3%,通道总压恢复系数均达到96%以上,均能满足设计要求,且换热器单元体内部没有出现流动恶化,故将代理模型优化设计应用于CW型原表面换热器的设计是可行的。

摘要：以实验研究为基础,利用以均匀试验设计法、最小二乘拟合和遗传算法寻优相结合的混合优化方法进行了环形扩压叶栅弯曲匹配数值优化研究。结果表明,优化的弯角和弯高范围随叶型折转角的增大而减小,合理选择弯曲方案将可以达到改善角区流动、减小损失的目的;叶片弯曲优化匹配设计可扩展现代压气机中弯曲叶片的应用范围,也表明了在大转角压气机中采用弯曲叶片设计方法的巨大潜力。

摘要：针对六足机器人的非结构化地形步行问题,研制了小型六足机器人HITCR-Ⅰ.设计了基于复合四连杆机构的腿部结构,使其具备全方位的运动能力.为了进一步提高机器人的运动性能,构建了描述六足机器人整体灵活度的表达式,并依据表达式进行了结构优化设计.基于"行为"和"功能"的思想对控制目标进行规划,设计了基于"功能-行为"控制体系构架的运动控制器,结合适应非结构化地形腿部运动轨迹的规划和基于局部规则的自由步态生成,实现了非结构化地形六足机器人有效且稳定的步行.最后通过实验验证了六足机器人系统HITCR-I非结构化地形的步行能力.

摘要：提出了一种基于戟形人工表面等离激元(spoof surface plasmon polaritons,SSPPs)的具有宽频带外抑制特性的紧凑型宽带带通滤波器.设计的滤波结构是通过在基板底层蚀刻周期性的戟形槽和在顶层加载带有月牙形贴片的微带到槽线过渡结构实现的.与传统的I形SSPPs相比,戟形SSPPs具有更好的慢波特性,基于戟形SSPPs设计的带通滤波器可以实现更紧凑的结构.设计的滤波器通带的上下截止频率可以分别通过调整SSPPs结构和微带到槽线过渡结构来调节.仿真结果表明,宽带带通滤波器中心频率为2.85 GHz,相对带宽为130%,通带内的回波损耗优于–10 dB,在5.6-20.0 GHz之间具有极强的–40 dB带外抑制.设计的宽带带通滤波器结构尺寸紧凑,仅为1.08λ_(g)×0.39λ_(g),其中λ_(g)是中心频率处的波长.为了验证宽带带通滤波器的有效性,采用传统的印刷电路板技术加工了宽带带通滤波器.测量结果与仿真结果吻合较好,验证了设计的可行性.本文所提出的宽带带通滤波器显示了在微波频率下开发SSPPs功能器件和电路的良好前景.

摘要：实验研究了设计冲角下压气机采用带切向缝隙大转角弯曲叶片对叶栅出口尾迹特性的影响,结果表明,切向缝隙射流能够有效地改善高负荷扩压叶栅的尾迹低速、低总压特性,减少尾迹高熵流体的加入以及尾迹亏损,从而降低了栅后总损失。

摘要：实验研究带有孔隙射流结构的某大折转角直扩压叶栅在设计冲角下的出口流场特性,分析了不同孔隙射流位置对出口流场的影响.结果表明:在叶片表面开孔隙后,降低开孔隙的叶高处出口气流折转能力,使叶栅性能下降;孔隙射流使尾迹速度增加,相应的尾迹损失降低,尾迹区范围减小,同时出口气流角沿节距方向分布更加均匀,开孔位置越靠近叶展中部,孔隙射流对尾迹的影响越明显;开多孔方案对叶栅出口流场的影响要强于单孔方案.

摘要：本文实验研究了在不同动、静叶间轴向间隙下静叶时序效应对某低速轴流压气机气动性能的影响．结果表明,相同轴向间隙下,时序效应对效率的影响随流量增加而增强,但对压比基本没有影响；在不同轴向间隙下,设计工况效率在67%轴向间晾时最大,33%间隙时最小,且最高、最低效率的静叶时序位置有所不同．综合变轴向间隙和时序位置的影响,压气机设计工况效率最大可提高1．0%,最大流量工况处可提高2．3%．但是随着轴向间隙的减小,压气机喘振裕度有所下降．