基于1-3压电复合材料的透镜式聚焦换能器设计

为了抑制压电陶瓷透镜式聚焦换能器振动的多模耦合现象,提高换能器电声转换效率,采用1-3压电复合材料,设计了一种新型的透镜式聚焦换能器;首先计算并仿真了1-3压电复合材料的厚度谐振频率ft和厚度机电耦合系数kt,理论和仿真结果分别相差2.947％和0.933％;接着对换能器做振动分析,结果表明,在换能器谐振频率ft处,声透镜中心径向振幅仅为厚度振幅的7.9％,径向振动得到有效抑制,这有助于提高换能器电声转换效率.     

层叠复合材料宽带换能器设计

利用多模耦合原理,将两片不同厚度的1-3型复合材料叠堆,制作宽带压电振子。用串并联理论与等效参数理论,计算不同厚度复合材料的谐振频率,得出构成层叠压电振子的两片复合材料的谐振频率差,并通过实验加以验证。结果显示,实验值与计算值吻合较好。将上述压电振子灌封,制作水声换能器并进行测试。结果表明,四只换能器的–3 d B带宽最大可达80 k Hz,最大发送电压响应均在163 d B以上。     

基于软模法制备1-3型压电复合材料及高频医用超声换能器

高频医用超声成像技术因其高空间分辨率而被广泛应用于人体组织的精细结构观察,其中高频超声换能器的核心材料是1-3型压电复合材料。采用软模板法直接烧结了锆钛酸铅(PZT)压电微柱阵列,进而制备PZT/环氧1-3型压电复合材料,并对其进行了微观结构观察和电学性能表征。材料微观结构完整,机电耦合系数达到0.64。采用此复合材料制备了中心频率为20 MHz的高频超声换能器。采用脉冲回波法对换能器进行了性能和声场测试,并利用其对人体皮肤进行了超声成像,换能器的插入损耗、带宽分别为13.1 dB和84.2%。结果表明,软模法制备的1-3型压电复合材料能使高频超声换能器兼具低插入损耗和大带宽,这为高性能高频医用超声换能器提供了一种低成本、高效率的商业化制备方法。     

一种新型的径向振动高频压电陶瓷复合超声换能器

 本文研究了一种新型的径向振动压电陶瓷高频复合超声换能器.该换能器由一个压电陶瓷圆环和一个嵌于其内部的金属圆盘复合而成.首先对压电陶瓷圆环及金属圆盘的径向振动进行了简单分析,推出了其机电等效电路和共振频率方程,分析了压电陶瓷圆环的几何尺寸对其共振及反共振频率的影响.在此基础上,分析了由压电陶瓷圆环和金属圆盘组成的复合换能器的径向振动,得出了其复合机电等效电路和共振频率方程.研究分析表明,对于具有相同外半径的压电陶瓷圆盘和压电陶瓷圆环,压电陶瓷圆盘的径向振动共振频率高于压电陶瓷圆环的径向共振频率,并且,压电陶瓷圆环的内半径越大,其径向共振频率越低.当在压电陶瓷圆环内部嵌入一金属圆盘而组成一径向复合超声换能器时,其径向共振频率高于压电陶瓷圆盘的径向共振频率,从而达到了提高换能器共振频率的目的.研制了一些径向复合高频超声换能器,并对其共振频率进行了测试,测试数据证明了理论结果的正确性.     

宽带高灵敏水声换能器的研究

为了提升声纳系统的探测性能，该文从扩展水声换能器带宽和提高灵敏度两方面出发，研制了一种“金字塔”结构的宽带高灵敏水声换能器，并选择单金属板空气柱型压电材料作为宽带高灵敏换能器的有源材料。对敏感元件进行机电等效分析和有限元仿真，获得压电材料尺寸的优选范围。根据多模耦合理论设计了“金字塔”型的换能器敏感元件结构。通过建立换能器的制作工艺流程，研制出宽带高灵敏换能器样机。测试结果表明，发送电压响应最高为182.9 dB,发射带宽为170 kHz,接收灵敏度最高达到-173.7 dB,接收带宽为110 kHz,-6 dB波束开角为8.1°。     

基于PZFlex的1-3压电复合材料横向振动模仿真

1-3型压电复合材料具有高机电耦合系数和低声阻抗,适用于制作水声和医疗超声换能器,但是1-3型压电复合材料的横向振动模会降低换能器的性能,限制换能器的小型化和高频化。该文设计了一组具有矩形压电陶瓷柱的1-3型压电复合材料,复合材料的厚度为0.32 mm,陶瓷柱宽度为0.08 mm,长度为0.10~0.25 mm,刀缝宽度为0.05 mm。利用有限元软件PZFlex进行了建模计算,仿真结果表明,复合材料的厚度谐振频率和反谐振频率分别为4.5 MHz、6 MHz,随着陶瓷柱长度的增大,横向谐振频率逐渐向低频处移动,当陶瓷柱长度和高度比值大于0.69时,横向谐振和厚度谐振发生模式耦合。该文基于复合材料设计了换能器,利用PiezoCAD软件计算得到换能器的中心频率为4.7 MHz。     

超快激光制备高频1-3型PIN-PMN-PT复合材料超声换能器

与其他压电材料相比,1-3型压电单晶复合材料具有优异的压电性能和更匹配的声学特性,更有利于制备出性能优异的超声换能器。该文通过有限元软件COMSOL对复合材料的振动模态及阻抗特性进行了系统的研究,同时采用皮秒激光制备了高频1-3型Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃(PIN-PMN-PT)铁电单晶/环氧树脂复合材料,并进行了性能表征。该1-3复合材料机电耦合系数为0.65,声阻抗为19.96 MRayls。该复合材料可用于制备高频超声换能器,结果表明,换能器中心频率为17.68 MHz,-6 dB带宽为84.38%,插入损耗为-25.4 dB。     

一种新型扭转振动压电陶瓷超声换能器

研究了一种新型扭转压电陶瓷超声换能器.基于机电类比原理,对切向极化的压电陶瓷薄圆环振子的扭转振动特性进行了研究,建立了其机电类比等效电路模型,从等效电路得出了环形振子的扭转振动频率方程的解析式及共振频率的计算公式.在此基础上,分析了换能器的共振与其几何尺寸间的关系;并利用有限元方法对压电陶瓷薄圆环扭转振动模态进行了分析.结果表明,在换能器压电陶瓷圆环内外半径比增大时,共振频率随之增大.     

糖类抗原CA125水平测定在结核性腹膜炎诊治中的意义

研究了一种新型扭转压电陶瓷超声换能器.基于机电类比原理,对切向极化的压电陶瓷薄圆环振子的扭转振动特性进行了研究,建立了其机电类比等效电路模型,从等效电路得出了环形振子的扭转振动频率方程的解析式及共振频率的计算公式.在此基础上,分析了换能器的共振与其几何尺寸间的关系;并利用有限元方法对压电陶瓷薄圆环扭转振动模态进行了分析.结果表明,在换能器压电陶瓷圆环内外半径比增大时,共振频率随之增大.     

压电复合换能器的结构对其频率特性的影响

研究了多模耦合宽频带复合换能器,结果发现,这种换能器在空气中的纵弯振动具有明显的规律性.针对1-3型压电复合材料,采用有限元法研究了压电陶瓷体积分数对换能器共振频率的影响,并研究了换能器共振频率与其几何尺寸间的关系.结果表明,换能器共振频率与压电陶瓷体积分数及其几何尺寸有关,即随压电陶瓷体积分数增加,共振频率增大;换能器前盖板几何尺寸越大,共振频率越小,纵振基频与弯振基频间距亦随之减小.     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

Complete approach to automatic identification and subpixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

A Versatile Mixed-Signal Pin Approach for Cost-Effective Test of Automotive ICs

Integrated circuits (ICs) intended for increasingly sophisticated automotive applications bring unique test demands. Advanced ICs for applications such as highly integrated automatic braking system (ABS) and airbag controllers combine high voltage digital channels, significant VI demands and precise timing capability. Along with continued missioncritical reliability concerns, the trend toward higher voltage operation and increased device integration requires specialized test capabilities able to extend across the wide operating ranges found in automotive applications. Among these capabilities, automotive test requirements increasingly dictate a need for a cost-effective versatile mixed-signal pin electronics with very high data rates reaching up to 50MHz with a voltage swing of-2 V to +28 V.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

Optical vibration and deviation measurement of rotating machine parts

It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer （LDV）.