【摘 要】
：
With the increasing miniaturisation and integration of electronic products and the increase of heat,it is necessary to design and introduce heat sinks and install fans.The volume of electronic components,especially the height,is very important for the str
【机 构】
：
School of Astronautics,Harbin Institute of Technology,Harbin 150001;Beijing Institute of Spacecraft
论文部分内容阅读
With the increasing miniaturisation and integration of electronic products and the increase of heat,it is necessary to design and introduce heat sinks and install fans.The volume of electronic components,especially the height,is very important for the structural and thermal design of electronic devices.This paper presents a design scheme of an online height measurement device based on laser triangulation and commercial charge coupled device(CCD).It analyzes the principles of electronic component height measurement,and expounds the composition and working principle of the laser measurement system.In addition,the commonly used methods to determine the cen-ter position are compared and analysed.These methods include circle fitting,gray centroid and extension method or Gaussian fitting.These methods usually lead to different results.The experimental results show that the fitting speed of the gray centroid is faster.The 3D model of components is given through measurement,and the error factors affecting measurement are analysed.
其他文献
目的 了解福建省成年人血脂异常的知晓率、治疗率和控制率及影响因素,为血脂异常的防治提供科学依据.方法 2017-2020年在福建省10个项目点开展心血管疾病高危人群早期筛查与综合干预项目,采用统一问卷收集社会人口学特征、生活方式、既往病史等信息,测量身高、体重、血压,检测血糖、血脂等生化指标.分析不同特征人群的血脂异常知晓率、治疗率和控制率,采用非条件Logistic回归模型探究其影响因素.结果 共筛查出119638名居民,血脂异常者为43569人,血脂异常率为36.42％,在血脂异常患者中,血脂异常的知
A safety design applies to every stage in a satellite system development life cycle to identify and analyze hazards in the satellite at a system level,eliminating or controlling various safety risks,while verifying the functions of the satellite system ha
为加强长江源区水生态研究,于2017年丰水期调查了长江源区5个湖泊、5条河流的水质和鱼类资源状况,并研究了其空间格局.水质综合指数(WQI)计算结果显示,长江源区WQI范围为41～87,评价等级介于差到良好之间,大部分采样点的水质评价等级为一般,其中,班德湖的水质评价等级为良好.主成分分析结果显示,长江源区河流、淡水湖、微咸水湖和咸水湖的水质指标呈现出明显的空间差异.河流水质呈现出较高的总磷、总氮、硝态氮、总悬浮物和浊度,淡水湖呈现出较高的水温、溶解氧及WQI,咸水湖呈现出较高的总碱度、总硬度、盐度、电导
目的 探讨荧光定量PCR法鉴定乳及乳制品中骆驼成分,为实现乳及乳制品的动物源性成分鉴别提供依据.方法 利用荧光定量聚合酶链式反应(real-time Fluorescent Quantitative Polymerase Chain Reaction,FQ-PCR)的方法构建了乳及乳制品中骆驼成分检测方法,设计了内参照与骆驼引物探针,对10份市售骆驼乳及乳制品进行调研性实验,检测其牛成分、羊成分及骆驼成分.结果 该方法特异性良好、灵敏度达到10-4 ng/μl,10份市售的骆驼乳及乳制品样本中全部检出骆驼
Common-track constellation is a special kind of constellation,all ground tracks of satellites are in one track.With recursive orbit or quasi-recursive orbit,the ground track of the constellation is a closed loop with a repeating track.In particular,if the
This paper presents a calculation method,and composition of a five-component force test device,to resolve the requirement for solid rocket motor multi-component force test.It compares the difference between two classical algorithms,and summarizes the stru
A fault tolerant control method is proposed in this paper for a turbofan engine gas path degradation through the full flight envelope.A Quantum-behaved Particle Swarm Optimization(QPSO)algorithm is applied to obtain engine inputs adjustments,which contrib
The accurate prediction for aerodynamic drag of spacecraft in very low Earth orbit(VLEO)is a fundamen-tal prerequisite for aerospace missions in VLEO.The present work calculates aerodynamic drag of the Gravity Field and Steady-State Ocean Circulation Expl
目的 了解龙岩市居民吸烟行为及其影响因素,为龙岩市控烟健康教育工作提供依据.方法 采用2020年龙岩市居民健康素养与吸烟行为监测数据,对1484名15～69岁龙岩市常住居民的现在吸烟、每日吸烟进行描述性分析,用Logistic回归分析吸烟行为的相关影响因素.结果 共发放问卷1497份,收回1484份,有效回收率为99.13％;居民现在吸烟率为23.04％(340/1476),每日吸烟率为21.54％(318/1476);男性每日吸烟率为41.99％高于女性0.82％(P＜0.01);15～24岁组每日吸烟
目的 通过对1981-2020年徐州铁路地区新发职业病流行病学调查,了解徐州铁路地区职业病流行特征,为预防控制职业病发生提供科学依据.方法 将1981-2020年新发职业病病例资料信息录入Excel 2017,对其在职业病种类构成、发病趋势、人群特征、高发部门等方面流行特征进行描述性流行病学分析.结果 1981-2020年新发职业病45例,职业病病例呈现逐年下降趋势,职业病种类主要涉及粉尘与化学因素两类职业病危害因素中的尘肺、职业性皮肤病和职业中毒3种,其中尘肺期别为3期:Ⅰ、Ⅱ、Ⅲ期.主要以矽尘为主,其