特殊加固SMD晶振的抗高过载性能研究

为了研究经过特殊加固的SMD石英晶振的抗高过载能力,选取同批次15只SMD石英晶振样品,利用自由式霍普金森压杆对样品进行高过载环境下的动态加载测试。结果表明,特殊加固处理的SMD石英晶振样品经过高过载试验可以正常工作,电气参数变化满足正常使用要求,频率变化率、阻抗变化分别在±5×10–6,±5Ω以内。     

抗高过载石英晶体元件的研制

使用一种简单实用的设计方法,采用特殊的结构设计,研制出的石英晶体元件具有抗高过载的能力.这种产品可制作的频率范围是3～60MHz,具有抗冲击力在1000～20000g,结合试验验证,这种石英晶体元件在经受高冲击后,仍然能够稳定的工作,所以充分证明了石英晶体元件通过采用这种特殊的结构,完全可以达到具有抗高过载（冲击力在1000～20000g）的能力.解决的关键问题是石英晶体元件晶片的设计、结构的设计及加工过程中应注意的问题.     

三角弹性托架抗高冲击石英晶体振荡器

抗高冲击石英晶体振荡器一直是我国军事通信的弱点.该文主要介绍了面向精确打击和导弹目标跟踪中使用的抗高冲击石英晶体元件的研发过程,分析了3～50 MHz频率段抗冲击力在2 000～20 000 g系列石英晶体振荡器的研制过程.结果表明,成功地研制出了高性能的抗高冲击石英晶体振荡器,为我国该类产品的小型化、频率点扩展、生产批量化奠定了基础.     

弹载测姿测量系统抗高过载技术研究

近年来,高新科技在军事领域迅速发展。对于未来的局部战争、炮弹射程、打击精度及机动速度等均是取得快速胜利的重要指标。因此,现在研究炮弹的制导化很有必要。在弹载制导系统中,弹体姿态测量系统是重要部分。该文对炮弹在高过载情况下的可靠性问题进行了研究,并针对高过载环境提出了一种基于微机电系统(MEMS)惯性器件弹载测量系统的抗高过载方法,通过有限元分析仿真和马歇特试验,对其抗高过载性能的设计进行了可行性分析与验证。试验结果表明,该文的抗高过载技术方案降低了在高过载环境下对弹载姿态测量系统的影响,能抵抗高冲击,达到了MEMS惯性姿态测量系统抗高过载特性的要求。     

抗过载微陀螺结构的高灵敏设计与仿真

为解决高过载微陀螺难以实现高灵敏检测的问题,设计了一种高灵敏且高过载的微陀螺结构。设计的微陀螺结构驱动模态与检测模态的频率高度匹配,提高了微陀螺的结构灵敏度。该微陀螺采用面内检测方式,驱动与检测模态阻尼类型主要为滑膜阻尼,实现了在大气压环境下微陀螺的高品质因数Q值设计。微陀螺均采用双悬臂梁设计,增加了微陀螺结构的稳定性,进而提高了其抗过载能力。最后通过微陀螺的器件级仿真,得到了所设计陀螺结构在驱动方向过载能力约为100 000g(g=9.8m/s~2),检测方向过载能力约为70 000g的前提下,结构灵敏度为53nm/[(°)/s]。     

硅振荡器的抗高过载实验设计与分析

硅振荡器是一种在高过载条件下有可能代替石英晶体振荡器为应用系统提供稳定时钟的振荡器。对硅振荡器开展高过载实验研究,具有重要的应用价值。论文以LTC6909I型硅振荡器为实验对象,对高过载环境下可能产生的频率漂移及是否损坏这两个主要方面进行了实验研究。实验证明了硅振荡器能经受高过载环境的考验,可以代替石英晶体振荡器为应用系统提供稳定时钟。     

钢基板厚膜环形电位器的研制

传统的陶瓷基板厚膜环形电位器不能承受高过载。选用不锈钢板作为基板材料,被覆绝缘介质,在其上印制厚膜电路,然后烧结,制作了钢基板厚膜环型电位器。该电位器经过温度循环、抗过载、机械强度和动态射击试验,结果表明:被覆绝缘介质不锈钢基板厚膜环型电位器具有过载值高(18000~20000g)、动态电阻装定精度高(误差小于1%)等优点,满足高过载使用要求。     

2007年5—7月颁布的部分电气与电子类IEC标准

1、IEC60068-2-69(2007年5月9日)环境试验——第2-69部分:试验—试验Te:通过湿度平衡法进行表面安装器件电子元器件(SMD)的可焊性试验2、IEC60587(2007年5月9日)严酷环境条件下使用的电绝缘材料——抗漏电和腐蚀试验方法3、IEC60605-6(2007年5月15日)设备可靠性试验——第6部分:恒定失效率和恒定失效密度4、IEC62005-9-2(2007年5月23日)光纤互连器件和无源光学元器件的可靠性——第9-2部分:单光纤连接器套的可靠性鉴定——单模5、IEC60068-2-82(2007年5月23日)环境试验——第2-82部分:试验——试验Tx:电子和电气元器件的晶须试验方…     

高过载姿态测量中MEMS陀螺失效模式与研究进展

高过载条件下姿态测量是一个公认的难题,其原因主要是角速度传感器难以经受高过载的冲击。基于微机电系统（MEMS）技术的陀螺作为解决高过载姿态测量问题的核心器件,其抗高过载能力直接制约着惯性导航系统在高过载环境中的应用。首先,介绍了弹药发射和侵彻两种典型高过载环境的特性,概括了在高过载环境中MEMS陀螺的响应类型;其次,总结了高过载条件下MEMS陀螺的失效模式,包括完全失效和功能性失效;然后,介绍了国内外在抗高过载MEMS陀螺方面的研究进展;最后,分别从器件设计和工程应用角度出发,提出了MEMS陀螺抗高过载的设计方法和应用思路。     

压电石英加速度传感器稳定性研究

分析了加速度传感器的量程、分辨率及晶体相关参数与传感器输出稳定性的关系,测试了不同环境状态下石英晶体谐振器的频率稳定性和加速度传感器的稳定性。试验结果表明,环境因素对石英晶体频率稳定性和石英加速度传感器稳定性有不同程度的影响,传感器稳定性的理论计算值与实测结果一致。     

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.     

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.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-