一种8毫米波变张角,半径突变多模圆锥馈源

我们研制了一种8毫米波变张角、半径突变的多模圆锥馈源。计算出其模比并推导出其辐射方向图公式;给出其在两个主平面——E平面与H平面上的辐射方向图和波束场分布特性的测试结果以及电压驻波比VSWR的测量结果;同时给出频带和旁瓣特性。分析与测试共同表明,在34.5GHz～37GHz频带里,该多模馈源的辐射图在大于24dB范围内获得幅度等化且不出现旁瓣,因此具有一定的应用价值。     

Contact interaction of double titanium and chromium diboride with Fe-Cr alloys

The kinetics of wetting double titanium and chromium diboride by iron-based alloys with different chromium content is studied. It is shown that contact angles are formed in such systems over the range 0–10°. The energy parameters of wetting are calculated. It is established that chromium as a surface-active element promotes Fe-Cr alloy spreading on the diboride surface. The microstructure of the interaction area is studied. It is shown that terminal solid solutions and eutectics are formed in the TiCrB₂-(Fe-Cr) system. The optimum compositions of the metallic binder are determined for TiCrB₂-based composite materials. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 1–2(453), pp. 109–115, 2007     

空间环型区域上的关联函数

本文利用锥函数方法，给出空间环型区域上关联函数的一种计算方法。     

钻削中产生迷切现象的机理研究

随着科学技术的发展．对孔加工精度的要求越来越高．钻削过程中的速切现象对孔加工的形状精度、位置精度有很大的影响．本文用试验、观察、解析的方法分析了钻头迷切现象与各种因素的关系，对提高孔加工精度有了新的揭示．     

板锥网壳结构的动力特性分析

板锥网壳结构是一种受力性能合理 ,技术经济效益良好的新型空间结构形式。对板锥网壳结构的自振特性及其影响因素进行了系统分析研究 ,并与普通双层网壳结构进行比较 ,得出了可应用于工程实践的重要结论     

凸轮机构推程、回程运动角的最佳匹配及其求解方法

在推程、回程运动角之和 Φ0 +Φ′0 =C(定值 )的情况下 ,必存在某一对推程、回程运动角的最佳匹配 Opti-m um{ Φ0 ,Φ′0 } ;当选用该最佳匹配时 ,对心式直动从动杆盘形凸轮基圆半径 r0 取得最小值 r0 min。本文在揭示出上述事实的基础上 ,研究解决了当选取最佳匹配 Optim um{ Φ0 ,Φ′0 }时 ,按许用压力角 [α]条件求解对心式直动从动杆盘形凸轮基圆半径最小值 r0 min的解析法。     

POM晶体倍频相位匹配角的设计及应用

计算了新型有机晶体ＰＯＭ的倍频匹配角，并将ＰＯＭ作为倍频器件用于超短光脉冲的测量中。     

Delaminations at the free edge of a composite laminate

The concept of a fracture process zone where damage takes place is used to analyse the delaminations at the free edges of angle ply laminates under uniaxial tension. The use of a fracture process zone removes the singularity in the interlaminar stresses and enables the initiation and growth of delaminations to be modelled for a perfect laminate without any assumed prior defects. Two different models for the stress displacement relationship in the fracture process zone are examined: a constant stress up to critical displacement and a linear relationship. Finite element analysis shows that there is little difference in the predictions obtained from the two models. An approximate analysis is presented for the constant stress stress-displacement model which is shown to agree with a finite element solution and experimental data. Hence it is argued that the approximate method using a constant stress model for the fracture process zone is sufficient for accurate prediction of delaminations.     

Visual recognition efficiency of handheld infrared thermometer interface information under low ambient illuminance

One of the symptoms of plagues, epidemics or pandemics is often a fever, so during such unprecedented times, handheld infrared thermometers are vital devices for monitoring symptomatic individuals. It is therefore very important to enhance reading efficiency when these thermometers are used for lengthy periods of time in a low illuminance environment. The need for the efficient reading of infrared thermometers or a fast reaction time when reading the information is even more relevant now during the COVID-19 pandemic. In this study, a target search experiment of digital characters is carried out through a simulated interface and use scenarios of a handheld thermometer based on three variables: the inclination angle or slant of the seven segment display characters, screen brightness, and ambient illuminance. The experimental results show that the inclination angle or slant of the characters and ambient illuminance have a significant effect on the reaction speed. In general, the slowest reaction time is found when reading characters with a slant of 10° to the left and the reaction time is the fastest with a right slant of 20°. A continued reduction in ambient illuminance does not affect the visual recognition performance but instead further enhances reading efficiency. Increasing the screen brightness increases the reaction time more in relatively low ambient illuminance conditions as opposed to relatively high ambient illuminance, which implies that in higher ambient illuminance conditions, a brighter screen needs to be used to obtain the same reaction speed as that in lower ambient illuminance conditions.