合成双射流激励器振动噪声特性

合成双射流激励器工作噪声远低于合成射流激励器工作噪声, 但其噪声特性仍然限制了其应用于笔记本电脑、空调、冰箱等室内电子设备散热. 为降低合成双射流激励器整体噪声, 采用数值模拟的手段探究合成双射流激励器在不同边界条件下的振动噪声特性, 为合成双射流激励器降噪设计提供指导. 结果表明: 压电振子与壳体的振动共同影响着激励器振动噪声声压级大小; 夹持条件对振动噪声影响很大, 压电振子处于夹支条件时, 激励器的振动噪声声压级比压电振子处于简支时的激励器最大声压级低10 dB.      

HL-2A装置中用户屏幕抓拍的功能实现

在HL-2A装置实验中，为了能及时了解远地系统的屏幕信息，充分利用真空质谱图和水系统监控屏幕等子系统的屏幕内容，开发了用户屏幕抓拍系统。该系统利用现有专用系统处理功能，将不能实时共享的屏幕输出结果，进行实时共享显示；同时，将专用系统的屏幕输出结果以图像的形式存储下来，供实验之后的共享交流。本文详细介绍该系统的功能特征以及包括系统设置、触发抓屏、热键抓屏、临时用户抓屏等多项应用实现。     

X86军用平板电脑电磁兼容性设计

X86平板电脑是军用移动信息系统的重要组成部分,具有性能高、兼容性强等优点,电磁兼容性是设备的关键指标。为满足X86平板电脑在环境恶劣的野战条件下的使用需求,需要对其进行针对性的电磁兼容性设计。通过分析X86平板电脑电磁干扰源,提出电磁兼容设计方法,包括屏蔽、滤波和PCB板设计等,重点是显示屏蔽和通信滤波设计。经试验分析,采取以上措施的X86平板电脑的电磁兼容性设计,能够满足国军标相关电磁兼容性要求。     

对称式布局介质阻挡放电等离子体激励器诱导启动涡

为了进一步提高等离子体激励器控制能力,采用粒子图像测速仪技术,以介质阻挡放电等离子体激励器为研究对象,开展了有、无来流条件下等离子体诱导启动涡的实验研究,获得了来流对启动涡发展演化及生存时间的影响.与传统非对称布局介质阻挡放电等离子体激励器相比,本文采用整个平板金属模型作为植入电极的对称布局方式开展研究.在金属模型表面粘贴聚酰亚胺胶带作为绝缘介质.将铜箔作为暴露电极沿平板展向布置,使激励器诱导气流沿流向方向.研究结果表明:对称布局式激励器会在暴露电极两侧产生一对方向相反的启动涡.在顺流向方向,来流加速了启动涡的破碎;在逆来流方向,来流延长了启动涡的生存时间,从而增加了激励器的掺混能力.该布局激励器具有掺混及射流效应两种能力,为提高等离子体激励器在高风速或高雷诺数下的控制效果积累了技术基础.     

非球面手机屏幕放大镜的设计

为方便老年人、视力障碍者等特殊人群看清手机上的文字及图像,采用ZEMAX光学设计软件,从高折射率材料,镜片面型和类型的选择上,以及从使用双胶合镜或非球面等方面设计了几款手机屏幕放大镜.通过分析手机屏幕放大镜特点,发现用非球面镜片不仅可以改善屏幕周边的像质并可减小镜片厚度.最后,还设计了几种放大镜与手机的契合方式,以克服现有手机放大镜片的不足.     

双通带异向平板波导的特性

提出了一种基于平板波导的新型异向谐振结构——交叉椅型谐振结构,通过理论分析和数值计算,说明和验证了单个交叉椅型谐振结构加载的平板波导具有双通带特性和异向特性;设计了一种由多个交叉椅型谐振结构周期加载的异向平板波导结构,并通过仿真实验验证了其负折射特性。交叉椅型谐振结构的全金属半封闭式结构和其特殊的电磁谐振方式,使得此类2维异向平板波导与传统的由金属开口谐振环与金属线正交阵列而成的2维异向介质相比,具有双通带、无介质损耗、功率容量大等特异性质;单个交叉椅型谐振结构加载的平板波导作为一种新型的滤波器结构,具有良好的双通带特性,尺寸较小。     

基于虚拟仪器的核电站主管道振动监测系统设计

针对主管道振动在线监测的迫切性需要,分析了主管道振动监测的原理;开展了核电站主管道振动监测系统的硬件设计和软件设计;采用LabView为开发平台,集虚拟仪器技术、设备组态图形技术和数据库管理技术于一体,实现了主管道振动的在线实时监测;利用电磁振动台模拟主管道的振动,验证了主管道振动监测系统的性能和基本功能。     

微矩形槽平板热管的设计制造及性能分析

目前微槽平板热管成为热管研究和开发的重点。文中简要介绍了平板热管的设计要点及制造工艺,并通过实验,对设计制作的平板热管进行了性能测试。得出如下结论:该平板热管具有良好的启动特性和工作特性;在设计中要注意工质与管壳材料的相容性;制作时要严格控制清洗、检漏、充装等关键工序以保证制作质量。     

基于光栅衍射原理测量手机屏幕光栅常量的居家实验

基于光栅衍射原理,利用手机屏幕作为反射光栅,设计出2种测量手机屏幕光栅常量的方法,并进行了实验验证.与传统测量手机屏幕光栅常量的方法相比,该方法采取正入射/掠入射方案,有效地避免了测量入射光角度等复杂步骤,具有简单、精准、易居家操作等优点.     

三网融合-物理层技术应用探讨

近年来,随着移动通信业务在全球范围内的迅猛发展,除了信息与话音等服务外,人们要求更多的多媒体业务,来满足日益发展的各种个性化需求.伴随着这种发展趋势,将以IP网为核心,不断整合网络融合和业务融合的关系,实现手机屏幕、电视屏幕、电脑屏幕三屏融合,并通过三屏融合来带动三网价值链的融合.以下将就未来可能的业务模式下的物理层技术应用模式进行介绍和探讨.     

射线面阵探测器成像系统校正研究

基于线性、移不变理论,对射线面阵探测器成像的特性和系统成像所呈现出亮度不均匀的原因进行分析研究.通过分析线性系统成立的假设条件,给出了对实际成像中各像元点阵的偏置、灵敏度进行逐点校正的公式.在实验室,对基于PaxScan2520 面阵探测器的成像系统进行成像校正研究,取得了满意的效果,噪声得到有效的抑制,成像的不一致性得到改善.当检测较厚工件或工件厚度变化较大时,系统成像超出其线性范围,给出了二次校正的方法和公式,也取得了满意的效果.     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.