渐变型声指向耦合器中声场的计算

提出一种新的计算波导中场分布的方法。该方法基于有限元法(FEM)，但采用人工透射边界，称之为有限元—人工透射边界法。并用渐变型声指向耦合器中表面声波导二维声场的计算实例说明该方法的实用性。     

基于TSV转接板的3D SRAM单粒子多位翻转效应

为了研究硅通孔(TSV)转接板及重离子种类和能量对3D静态随机存储器(SRAM)单粒子多位翻转(MBU)效应的影响,建立了基于TSV转接板的2层堆叠3D封装SRAM模型,并选取6组相同线性能量传递(LET)值、不同能量的离子(¹¹B与^4He、²⁸Si与¹⁹F、⁵⁸Ni与²⁷Si、⁸⁶Kr与⁴⁰Ca、¹⁰⁷Ag与⁷⁴Ge、¹⁸¹Ta与¹³²Xe)进行蒙特卡洛仿真。结果表明,对于2层堆叠的TSV 3D封装SRAM,低能离子入射时,在Si路径下,下堆叠层SRAM多位翻转率比上堆叠层高,在TSV(Cu)路径下,下堆叠层SRAM多位翻转率比Si路径下更大;具有相同LET值的高能离子产生的影响较小。相比2D SRAM,在空间辐射环境中使用基于TSV转接板技术的3D封装SRAM时,需要进行更严格的评估。     

A New Method to Analyse Two-Side Tapered Waveguides

We discuss the characters of two-side tapered waveguides. Then, based on some approximations, a simple but practical and efficient method is developed to design the taper waveguide. The results are compared with other methods in a good agreement.     

掺镱包层光纤激光器的全光纤调Q技术

从理论和实验两方面对掺镱包层全光纤调Q激光器进行了研究.建立了相应的理论模型,根据调Q光纤激光器的速率方程理论,用基于"能量利用率与初始反转粒子数关系"求解剩余反转粒子数的新方法,得出了调Q光纤激光器的初始参数诸如抽运功率、纤芯直径、光纤长度、输出透过率等影响脉冲宽度和脉冲能量的规律,进一步明确了压缩脉冲宽度和提高脉冲能量的方法;优化了相关参数,为同类调Q光纤激光器的设计提供参考.实验用半导体激光器(LD)作为抽运源,增益光纤为D形双包层掺镱光纤.谐振腔高反端串接一个带尾纤的声光Q开关,实现了重复频率在10 Hz~100 kHz范围内可调声光调Q掺镱全光纤激光器的实验运转;在重复频率500 Hz时,脉冲宽度为3μs,脉冲能量达到2.94 mJ.     

Development of MEMS-based micro capacitive tactile probe

In this paper, a micro capacitive sensor with nanometer resolution is presented for ultra-precision measurement of micro components, which is fabricated by the MEMS （micro electromechanical systems） non-silicon technique. Based on the sensor, a micro capacitive tactile probe is constructed by stylus assembly and packaging design for dimension metrology on micro/nano scale, in which a data acquiring system is developed with AD7747. Some measurements of the micro capacitive tactile probe are performed on a nano positioning and measuring machine （NMM）. The measurement results show good linearity and hysteresis with a range of 11.6 μm and resolution of better than 5 nm. Hence, the micro capacitive tactile probe can be integrated on NMM to realize measurement of micro structures with nanometer accuracy.     

折叠翼面展开过程中气动载荷特性数值模拟

针对某飞行器翼面高速展开过程,采用定常和非定常数值模拟两种不同方法,进行折叠翼面展开过程气动载荷分析研究,其中定常方法主要研究翼面从折叠到展开过程中不同展开角下外翼面的气动特性,分析展开角、来流参数对外翼面气动力的影响;非定常方法主要模拟折叠翼面展开角速度变化,从而获得典型工况下翼面展开过程的载荷情况,分析非定常效应对气动载荷的影响.研究发现,当翼面展开速度与来流速度相近时,则非定常效应不可忽略而必须采用非定常模拟方法.      

Nano-Traceability Study of a Cr Standard Grating Fabricated by Laser-Focused Atomic Deposition

A dimensional artifact is developed, which is a chromium （Cr） deposition grating fabricated by a laser-focused atomic deposition technique. The mean pitch of the grating is measured by using a metrological atomic force microscope with a large range, where a series of reference signs have been performed to locate the deposition area. Cosine error of the measurement result is analyzed and eliminated by the iterative angle calibration. The measurement result shows that the mean pitch of the grating is 212.66 ±0.02nm, which is very close to half of the standing laser wavelength （λ = 425.55 nm）. This means that the grating has traceability with high accuracy and can substitute the laser interference technology for instrument calibration. Moreover, using the Cr deposition grating as a nano standard can shorten the traceability chain and improve the practical application.     

Switchable down-, up- and dual-chirped microwave waveform generation with improved time-bandwidth product based on polarization modulation and phase encoding

A switchable down-, up- and dual-chirped microwave waveform generation technique with improved time-bandwidth product (TBWP) is proposed and demonstrated based on a dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) cascaded with a polarization modulator (PolM). By properly controlling the phase shifts of the radio frequency signals applied to the DP-DPMZM, switchable down-, up- and dual-chirped waveforms with simultaneous frequency and bandwidth doubling can be generated. To enlarge the TBWP further, splitting parabolic signal and phase-encoding splitting parabolic signal are used to drive the PolM for the enhancement of bandwidth and time duration. Numerical results demonstrate the generation of down-, up- and dual-chirped microwave waveform with TBWP of 8, 160 and 10240. The proposed method may find applications in future multifunction radar systems due to the high performance and flexibility.