基于双因素方差分析的混响室搅拌器优化研究

针对混响室搅拌器的优化问题,建立了混响室仿真模型,分析了搅拌器叶片不同夹角和不同边长比对混响室场均匀性的影响,得到了叶片较优夹角和较优边长比。通过对仿真数据进行双因素方差分析,得到搅拌器叶片夹角和边长比对场均匀性影响的权重关系。该结论为混响室搅拌器的优化设计提供了指导依据。     

混响室设计技术研究

介绍了混响室发展的历史及工作原理及设计方案,阐述了其在电磁兼容测试中的应用,并讨论了其优缺点。通过查阅、分析和研究大量国外资料,给出了混响室设计的一些基本原则。     

某数字电路混响室与GTEM室连续波辐照对比试验研究

利用实验室建成的大型混响室和GTEM室,分别对某典型数字电路进行了连续波辐照电磁环境效应试验,分析了不同测试环境对数字电路的干扰作用规律,获取了受试电路在各种状态下的干扰阈值。通过对测试结果的对比分析,确定了混响室与GTEM室两种测试方法辐照效应的相关性,为混响室测试标准的制定提供了理论依据。     

基于混响室的电场探头校准方法研究

针对电场探头在高场强下的校准需求，本文提出了利用混响室开展电场探头校准，介绍了基于混响室的电场探头校准原理和校准方法，解决了200V/m以上高场强环境下电场探头的校准问题，并与微波场强标准中的测量结果进行了对比分析。两组测量结果具有较好的一致性。     

发射天线配置对混响室性能的影响研究

为了优化混响室的结构设计,采用基于矩量法的电磁仿真软件FEKO分别对不同发射天线配置时混响室内的电磁场进行了仿真计算,考察了发射天线的种类和位置对混响室场性能的影响,结果表明选择合适的发射天线并进行合理的位置设计能显著改善混响室内电场的性能。     

基于混响室的电磁环境及自然环境综合试验箱设计和仿真技术

本文提出一种基于混响室平台将电磁环境和自然环境结合的综合试验箱集成技术，该试验箱集成了环境试验条件和电磁辐射敏感度试验条件，可以在高低温、湿热、温度循环、温度冲击等多种环境条件下同时对电子设备施加电磁辐射干扰，考核电子设备在同施加环境应力和电磁应力的复杂条件下的适应性。经过设计、建造和测试，该集成技术满足各项预期指标并容易进行推广，可进一步降低设备试验成本。     

一种符合国际标准规定的振动传感器声场灵敏度校准方法

本文提出一种新的振动传感器声灵敏度校准方法。它用一个简易的木箱作为混响室,并采用磁带随机技术,使混响箱内产生一个符合国际标准(ISO 5347)规定谱型和总声压级的随机噪声场,从而完成振动传感器的声场灵敏度校准。这种方法简易方便,成本低,易于推广。     

日本新一代大型航天器环境试验设备

为了空间事业发展的需要,从1970年起,日本宇宙开发事业团在筑波宇宙中心建起了一整套卫星环境试验设备,其中有: 直径8米、高25米的空间环境模拟器,它装有光束直径为4米的离轴式太阳模拟器; 推力达140千牛顿的电磁振动台系统; 体积为910立方米的声学混响室; 直径15米的磁试验设备。这些设备已经完全能够满足1990年以前日本中小型卫星研制计划(对地静止卫星重550公斤量级)的需要。     

飞机舱内噪声综合治理技术

针对某国产飞机改装中遇到的舱内噪声问题,进行了飞机舱内噪声空测,摸清了噪声的属性,在声学试验室对国内外多种先进的降噪材料进行了性能摸底和对比试验,并针对螺旋桨飞机降噪特点专门研制了皱褶芯材夹层板这一集隔声和装饰功能于一体的新型材料.为了在地面真实地模拟和测试螺旋桨飞机的舱内噪声,提出了一种混响室-消声室隔声性能试验方法,利用一个废弃的机身段,进行了降噪效果验证试验,对比了各种降噪材料在不同组合下的降噪效果,在此基础上,确定了多种组合降噪措施综合使用的降噪方案.经机上应用和空中试飞表明:降噪效果达到了要求.     

法国建造热真空试验设备

法国宇航工程环境试验中心（ＩＮＴＥ－ＳＰＡＣＥ）目前正在兴建一台大型热真空试验设备──ＳＩＭＭＥＲ。自１９６９年该中心在图鲁兹建立以来，在它的试验大厅内已经建立起一整套用于整星级试验的设备，其中有直径７ｍ，长９ｍ，配备有直径３．８ｍ太阳模拟器的大型空间模拟器；推力为３００ｋＮ的多电动振动台系统；体积１０００ｍ３的声混响室；体积１６×１０×１１ｍ３的用于ＥＭＩ／ＥＭＣ试验的吸波室和承重４ｔ的质量特性测试设备等。然而考虑到未来不断扩大的全球卫星市场，适应下一代阿里安－５火箭的有效载荷的试验要求，决定…     

双储液器环路热管的设计与实验研究

设计了一套双储液器环路热管以解决其重力场中运行受方位限制的问题,介绍了通过储液器体积和工质充装量的匹配设计避免最难启动情形发生的方法,并进行了相关的实验研究。实验验证了双储液器环路热管重力场中运行不受方位限制的特性,并且发现,在可变热导区的一定的热载荷范围内,双储液器环路热管在不同姿态下稳态运行温度不相同,而其他热载荷区域内却基本一致。文章分别从储液器能量平衡和回流液体过冷量有效利用率的角度进行了分析和解释。     

Reverberation time lags in the high luminosity quasar PG 1247+267

Virial estimates of the black hole mass in the center of AGNs, derived from single-epoch observations of luminosity and emission line widths, are now available for several thousands of objects at all redshifts and luminosities, so that studies of the cosmological evolution of the AGN mass function are becoming possible. These estimates are based on the empirical luminosity-size relation measured through reverberation mapping at low redshifts and luminosities. For this reason the spectrophotometric monitoring of 4 luminous quasars was started in 2003, with the 1.8 m telescope of the Asiago Observatory. To measure the reverberation time lag we adopt a method, recently introduced by Zu et al. (2011), which takes advantage of the available statistical information on variability autocorrelation and makes simple assumptions on the continuum-emission line transfer function. We present the estimate of the broad line region size for the quasar PG 1247+267, which is the most luminous object with reverberation measures to date. Virial products computed for C iv and C iii] emission lines provide consistent results. A possible flattening of the size-luminosity relation for C iv at high luminosity is suggested.     

Modeling gas exchange in a closed plant growth chamber.

Fluid transport models for fluxes of water vapor and CO2 have been developed for one crop of wheat and three crops of soybean grown in a closed plant growth chamber. Correspondence among these fluxes is discussed. Maximum fluxes of gases are provided for engineering design requirements of fluid recycling equipment in growth chambers. Furthermore, to investigate the feasibility of generalized crop models, dimensionless representations of water vapor fluxes are presented. The feasibility of such generalized models and the need for additional data are discussed.     

Sealed environment chamber for canopy light interception and trace hydrocarbon analyses.

Two sealed chambers were constructed, each measuring approximately 4.5 m x 3 m x 2.5 m (LxWxH). Heat exchangers and air handling components were integrated within the sealed environment. Construction materials were chosen to minimize off-gassing and oxidation. Acceptable materials included stainless steel, Teflon (TM), glass and Heresite (TM) or baked enamel coated metal parts. The glass-topped chambers have externally mounted microwave powered light sources providing minimum PAR at canopy level of 1000 micrometers m-2 s-1. Major gases (CO2, O2) were monitored. Other environmental variables relevant to plant production (humidity, temperature, nutrient solution) were monitored and controlled continuously. Typical environment control capability and system specifications are presented. The facility is described as a venue ideally suited to address specific research objectives in plant canopy light interception, such as the roles of novel microwave powered overhead and inner-canopy light sources for dense plant canopies. In addition, control of recycled hydroponic nutrient solutions and analysis of trace atmospheric hydrocarbons in the context of sealed environment life support can be concurrently monitored.