机械式随钻震击器卡瓦工作过程仿真分析

针对某机械式随钻震击器的卡瓦在工作过程中断裂的问题,应用三维建模软件UG对卡瓦及其相邻工作零件进行建模,并应用Nastran仿真模块进行工作过程中非线性接触等效应力分析。结果表明:卡瓦的应力集中区域位于卡瓦与定位套接触端第1圈内齿齿根处,与卡瓦零件的断裂点一致,为卡瓦的改进设计提供了依据。     

Manurite 900钢高温制氢炉管服役后的焊接修复

通过金相组织观察、常温力学性能、常温冲击功测试等方法,分析了Manurite 900钢高温制氢炉管长期服役后的性能变化及对焊接性的影响,通过固溶处理改善了服役炉管的性能。判定了服役制氢炉管焊接裂纹的性质,研究了服役Manurite 900钢高温制氢炉管的抗液化裂纹能力及开裂倾向。分析了液化裂纹的成因及产生机理,提出了焊接修复的工艺方法和工艺原则。     

Hierarchical Magnetic Network Constructed by CoFe Nanoparticles Suspended Within “Tubes on Rods” Matrix Toward Enhanced Microwave Absorption

Hierarchical magnetic-dielectric composites are promising functional materials with prospective applications in microwave absorption(MA)field.Herein,a three-dimension hierarchical“nanotubes on microrods,”core–shell magnetic metal–carbon composite is rationally constructed for the first time via a fast metal–organic frameworksbased ligand exchange strategy followed by a carbonization treatment with melamine.Abundant magnetic CoFe nanoparticles are embedded within one-dimensional graphitized carbon/carbon nanotubes supported on micro-scale Mo2N rod(Mo2N@CoFe@C/CNT),constructing a special multi-dimension hierarchical MA material.Ligand exchange reaction is found to determine the formation of hierarchical magnetic-dielectric composite,which is assembled by dielectric Mo2N as core and spatially dispersed CoFe nanoparticles within C/CNTs as shell.Mo2N@CoFe@C/CNT composites exhibit superior MA performance with maximum reflection loss of−53.5 dB at 2 mm thickness and show a broad effective absorption bandwidth of 5.0 GHz.The Mo2N@CoFe@C/CNT composites hold the following advantages:(1)hierarchical core–shell structure offers plentiful of heterojunction interfaces and triggers interfacial polarization,(2)unique electronic migration/hop paths in the graphitized C/CNTs and Mo2N rod facilitate conductive loss,(3)highly dispersed magnetic CoFe nanoparticles within“tubes on rods”matrix build multi-scale magnetic coupling network and reinforce magnetic response capability,confirmed by the off-axis electron holography.     

经纬仪红外基准点误差修正及分析

经纬仪的红外测量数据含有基准点误差,在数据处理中,该误差对目标定位精度的影响往往被忽视.文中提取了经纬仪摄影轴之间的几何关系,由几何示意图推导了误差修正公式,分析了基准点误差问题.仿真结果表明,基准点误差严重影响目标定位精度,在红外数据处理中必须予以修正.     

Current–voltage characteristics of AlCdO Schottky contact on the polished and unpolished p-type Si surfaces with and without light illumination

In this study, the current-voltage characteristics of the AlCdO/unpolished p-type Si and AlCdO/polished p-type Si Schottky diodes with and without light illumination were examined. It is found that the Schottky barrier height (the series resistance) of the AlCdO/unpolished p-type Si Schottky diode is higher (lower) than that of the AlCdO/polished p-type Si Schottky diode. The power conversion efficiency of the AlCdO/p-type Si devices in the light (AM 1.5 G, 100 mW/cm²) was improved by increasing built-in potential at the AlCdO/p-type Si interfaces and reducing the device series resistance and surface reflectivity. It is shown that the device surface roughness plays an essential role in improving the device performance.     

Dieless drawing steel wires using a dielectric heating method and modeling the process dynamics

Modern industries require the production of multi-functional, inorganic, micron-sized metal wires. This study suggests a novel method that could potentially offer a highly efficient dieless drawing technology for manufacturing thin stainless steel fibers. The method is based on a hot-working principle, using microwaves as the heat source and SiC as the susceptor. Experimental trials with a laboratory rig showed that the new system worked effectively for drawing the stainless steel wires and should be able to realize the diameter attenuation with a diameter reduction of up to 21%. The theoretical model describing the deformation behavior of the stainless steel wires in the working zone along with the constitutive equation of Bingham model modified with a power law and Zener–Hollomon parameter turned out to match very good with the actual results of the experiment. The coefficient of variation of the drawn wire diameter increased, as the draw ratio increased, which could be attributed to the occurrence of the narrow necking zone.     

Study on the hydrothermal drying technology of sewage sludge

Drying of sewage sludge is an effective way for treatment and utilization of sewage sludge,where reduction of energy consumption is one of the major technical challenges.So we experimentally investigated the possibility of the hydrothermal treatment.We have found that treatment of sewage sludge by saturated steam with the temperature of 190°C and pressure of 20 bar can dramatically improve the dehydration performance of the slurry like product.And the water content can be reduced down to about 55% by a mech...     

环形槽应力释放法中应力零点槽深数值计算

在预应力混凝土现存预应力的研究方面提出了环形槽应力释放法,对两根预应力混凝土梁进行了分析,解决了应力释放法中最重要的最佳槽深问题,并探讨应力零点槽深的影响因素,对实际工程具有一定的指导意义。