摘要：The design of exhaust hood is a typical high dimensional,expensive computational and black box ***-Point Search based Efficient Global Optimization(MSEGO)is proposed to solve this *** is used for the aerodynamic performance optimization of a low exhaust hood with non-axisymmetric outer flow *** optimization,the static pressure coefficient of the exhaust hood increases by 284.54%,and the aerodynamic performance analysis explains the reason of the ***,the analysis of variance(ANOVA)as the data mining technique is used to extract information of design space and analyze the influence of variables on the *** aerodynamic performance analysis and data mining,it indicates that non-axisymmetric outer flow guider and the width of outer hood has a significant effect on the aerodynamic ***,design lessons are derived and accumulated for the optimization of similar designs.

摘要：结合双控制型线端壁造型方法,建立了带有槽缝射流和非轴对称端壁造型的燃气透平叶片端壁的数值研究模型。在验证数值方法正确性的基础上,开展了不同非轴对称端壁设计对叶片端壁综合传热性能影响的研究。结果表明,不同的非轴对称端壁造型会对所研究的大转折角叶片的二次流结构产生不同的影响。在叶栅通道前部造型会降低槽缝射流对端壁前部的气膜冷却作用,而叶栅通道后部的端壁造型能够有效提高整个端壁的气膜冷却作用。对传热特性而言,在叶栅通道前部进行端壁造型能够有效降低通道前部的端壁传热强度,在端壁后部造型可以减小通道中后部的端壁传热强度。综合考虑冷却和传热特性,在叶栅通道后部进行非轴对称端壁造型能够有效提高端壁的综合传热性能,降低热负荷,更加有利于叶片端壁的热防护。

摘要：深部巷道大变形已成为深部煤炭安全高效开采的关键制约因素。为实现深部软弱围岩稳定性控制,提出了基于深部巷道大变形演化过程的分步联合支护方案及其理论分析模型。结果表明,深部软弱围岩呈破裂碎胀变形-损伤扩容变形-连续变形的分布特征。分步联合支护后,围岩极限承载力随锚杆和锚索等效支护力增大呈线性增大趋势,但随注浆修复系数呈指数增大趋势。锚杆和锚索支护设计时应以极限承载力所需的注浆修复系数等于1.0时的等效支护力临界条件为基准。深浅孔注浆支护时须同时考虑注浆修复系数和围岩破裂区半径。不同支护措施的协同支护参数可由破裂修复区围岩极限承载平衡条件确定。数值模拟和工程应用分析表明,分步联合支护可实现深部软弱围岩碎胀大变形控制,具有较高的工程推广应用价值。

摘要：采用有限元仿真手段,研究不同中径过盈量下AG6×1过盈螺纹副应力分布、危险截面以及安装扭矩,并通过实验测试了不同中径过盈量下AG6×1过盈螺纹的安装扭矩。通过有限元仿真计算可得:当AG6×1过盈螺纹中径过盈量大于0.030 mm并小于0.060 mm时,其铸造镁合金(ZM6)基体上应力大于176.0 MPa,小于278.9 MPa,位于ZM6弹塑性变形范围,即AG6×1过盈螺纹达到预紧状态;AG6×1过盈螺纹中径过盈量和施加的安装扭矩范围分别为0.030~0.060 mm和5.83~11.19 N·m;AG6×1过盈螺纹副旋合的第一个螺纹小径处承载应力最大,是最容易失效部位。实验结果显示,通过有限元计算得到的安装扭矩值与实测的安装扭矩值近乎一致。

摘要：Chemically modified carbonaceous materials have attained utmost attention in the fields of renewable energy storage and conversion,due to the controllable physicochemical properties,tailorable micro-/nanostructures,and respectable ***,P-doped mesoporous carbons were synthesized by using F127 as the soft template,organophosphonic acid as the P source and phenolic resin as the carbon *** amounts of iron species were introduced to act as a graphitization *** synthesized carbons exhibit the well-defined wormhole-like pore structure featuring high specific surface area and homogenously doped P ***,introducing iron species during the synthesis process can optimize the textural properties and the degree of graphitization of carbon *** doping amount of P has an important effect on the porous structure and the defect degree,which correspondingly influence the active sites and the oxygen reduction reaction(ORR)*** resultant material presents superior catalytic activity for the ORR,together with remarkably enhanced durability and methanol tolerance in comparison with the commercial Platinum catalyst,demonstrating the possibility for its use in electrode materials and electronic nanodevices for metal-air batteries and fuel cells.

摘要：The relationship between noise variance and spatial resolution in grating-based x-ray phase computed tomography（PCT） imaging is investigated with reverse projection extraction method, and the noise variances of the reconstructed absorption coefficient and refractive index decrement are compared. For the differential phase contrast method, the noise variance in the differential projection images follows the same inverse-square law with spatial resolution as in conventional absorption-based x-ray imaging projections. However, both theoretical analysis and simulations demonstrate that in PCT the noise variance of the reconstructed refractive index decrement scales with spatial resolution follows an inverse linear relationship at fixed slice thickness, while the noise variance of the reconstructed absorption coefficient conforms with the inverse cubic law. The results indicate that, for the same noise variance level, PCT imaging may enable higher spatial resolution than conventional absorption computed tomography（ACT）, while ACT benefits more from degraded spatial resolution. This could be a useful guidance in imaging the inner structure of the sample in higher spatial resolution.

摘要：针对近地无线信道变化多端的多径现象,该文提出了一种用于复杂信道环境下的低功耗无线传感网Rake接收机VLSI方案并在FPGA上实现。仿真和应用表明,该Rake接收机不仅具有良好的抗多径衰落性能,而且与常规Rake接收机相比,显著节省了VLSI资源并降低了功耗。

摘要：为了提高星载铯钟的频率准确度,依据星载铯钟C场系统的设计要求,运用毕奥—莎伐尔定律计算线圈磁场,设计并分析了C场磁场系统。通过数值计算证明了设计的合理性,得到了最佳的主C和副C线圈匝数等参数,改善了原子束流轨迹上磁场强度的均匀性并得到试验验证,可将信号的频率准确度提高一个量级。

摘要：为了强化布置三角形涡发生器的U型通道综合换热性能,耦合基于子元模型的全局优化算法、三角形涡发生器参数化方法、三维RANS方程求解技术与基于总变差分析的知识挖掘技术,建立了高效的三角形涡发生器综合换热性能优化与知识挖掘方法。在验证本文数值方法正确性的基础上,以综合换热性能最优为目标函数,对布置于U型通道内的三角形涡发生器进行设计优化与知识挖掘。优化后,最优设计的三角形涡发生器诱导产生的下洗涡对的强度和间距增加,使得U型通道的综合换热性能相对提高了14.5%。同时对设计空间进行知识挖掘,筛选对综合换热性能影响显著的设计变量,分析显著变量对目标函数的影响机制。结果表明:三角形涡发生器的高度对通道换热能力和阻力损失的影响最为显著,而三角形涡发生器的宽度对通道综合换热性能的影响最为显著。

摘要：对影响无线传感器网络链路质量的几个因素进行分析,根据分析结果,在IEEE 802.15.4协议标准基础上,对MAC层帧格式、数据传输机制等做出相应修改,进而设计出一种用于测量无线传感器网络链路质量的方法.该方法避免了由于帧长度不同而带来的影响,使传感器节点能够更好地对通信链路进行数据采集.最后,分别运用IEEE 802.15.4与修改后的方法进行实际测量,对所测得的数据进行了分析、比较和评价.