固态放大器控制保护电路的电磁兼容设计

以某固态放大器控保电路的设计为例,分析在大功率电路中应用CPLD所存在的电源系统干扰、电路干扰、地线噪声干扰和辐射干扰等电磁干扰,并分析这些电磁干扰产生的主要原因.为了抗干扰,从结构设计、电路设计、PCB设计和元器件布局等方面考虑,采用了隔离、屏蔽、滤波、合理接地等具体措施.     

Comparison of Solid-State Microwave Annealing with Conventional Furnace Annealing of Ion-Implanted SiC

Rapid solid-state microwave annealing was performed for the first time on N⁺-, Al⁺-, and B⁺-implanted SiC, and the results were compared with the conventional furnace annealing. For microwave annealing, temperatures up to 2,000 °C were attained with heating rates exceeding 600 °C/s. An 1,850 °C/35 s microwave anneal yielded a root-mean-square (RMS) surface roughness of 2 nm, which is lower than the 6 nm obtained for 1,500 °C/15 min conventional furnace annealing. For the Al implants, a minimum room-temperature sheet resistance (R _s ) of 7 kΩ/□ was measured upon microwave annealing. For the microwave annealing, Rutherford backscattering (RBS) measurements indicated a better structural quality, and secondary-ion-mass-spectrometry (SIMS) boron implant depth profiles showed reduced boron redistribution compared to the corresponding results of the furnace annealing.     

Investigation of the Phase Equilibria of Sn-Cu-Au Ternary and Ag-Sn-Cu-Au Quaternary Systems and Interfacial Reactions in Sn-Cu/Au Couples

The phase equilibria of the Sn-Cu-Au ternary, Ag-Sn-Cu-Au quaternary systems and interfacial reactions between Sn-Cu alloys and Au were experimentally investigated at specific temperatures in this study. The experimental results indicated that there existed three ternary intermetallic compounds (IMCs) and a complete solid solubility between AuSn and Cu₆Sn₅ phases in the Sn-Cu-Au ternary system at 200°C. No quaternary IMC was found in the isoplethal section of the Ag-Sn-Cu-Au quaternary system. Three IMCs, AuSn, AuSn₂, and AuSn₄, were found in all couples. The same three IMCs and (Au,Cu)Sn/(Cu,Au)₆Sn₅ phases were found in all Sn-Cu/Au couples. The thickness of these reaction layers increased with increasing temperature and time. The mechanism of IMC growth can be described by using the parabolic law. In addition, when the reaction time was extended and the Cu content of the alloy was increased, the AuSn₄ phase disappeared gradually. The (Au, Cu)Sn and (Cu_,Au)₆Sn₅ layers played roles as diffusion barriers against Sn in Sn-Cu/Au reaction couple systems.     

2-甲基-8-（9，9-二丁基芴）-3，5，7-三炔-2-辛醇的合成和性质研究

合成了一种新颖的乙炔衍生物，2-甲基-8-（9，9-二丁基芴）-3，5，7-三炔-2-辛醇（6a），并利用红外光谱（IR），紫外光谱（Uv），核磁（NMR），质谱（MS）等对其结构进行了表征。利用红外光谱（IR）和紫外光谱（Uv）对其拓扑固相聚合性质进行了研究。实验结果表明，这些化合物在加热和紫外光照射条件下都能够发生固相聚合，但得到的是结构复杂的聚合物。     

CAN总线嵌入式系统在发射机中的应用

介绍了一种适用于固态发射系统的嵌入式系统设计及应用。该系统通过采用单片机与CPLD技术的有机结合设计，运用CAN总线技术，实现控制系统对数量众多的工作状态信息、故障信息的实时监测与通信控制。文中分别从冗余双监控系统设计、单片机嵌入式系统、CPLD的应用、CAN总线技术以及针对RF高功率所采取的电磁兼容设计考虑等不同方面对其工作原理进行了详细阐述。     

Coupled hygro-thermo-viscoelastic fracture theory

A coupled hygro-thermo-viscoelastic fracture theory is developed for quasi-static and dynamic crack propagation in viscoelastic materials subject to combined mechanical loading and hygrothermal environmental exposure based on fundamental principles of thermodynamics. The Helmholtz free energy is taken to be a functional of the histories of strain, temperature and fluid concentration with the crack parameter being introduced as an internal state variable. A thermodynamically consistent time-dependent fracture criterion for crack propagation in the presence of thermally and mechanically assisted fluid transport is obtained from the global energy balance equation and the requirement of non-negativity of the global energy dissipation rate, which is generally applicable to both quasi-static and dynamic loading and both isothermal/isohumidity and non-isothermal/non-isohumidity conditions with classic fracture criteria as special cases. On the basis of the developed theory, the generalized energy release rate method, the generalized contour integral method and the extended essential work of fracture method are proposed for fracture characterization of load-carrying viscoelastic materials in hygrothermal environments, and the interrelation of these methods and their correlation with conventional methods and existing models, simulations and experiments are discussed.     

有色噪声的扩散过程模型

研究使用基于随机微分方程的扩散过程模型产生有色噪声.首先给出Markov扩散过程的平稳分布,该分布给出了扩散过程模型中的漂移系数、扩散系数和有色噪声概率密度分布之间的关系;选择扩散过程模型中的扩散系数为x的一次幂,其系数决定了所生成噪声的相关特性;数值算法使用Milstein高阶法.以三元独立积构造的G-分布雷达杂波为例进行仿真分析,验证所提出方法的准确性和有效性.     

Determination of isothermal section of Ag-Ti-Zr ternary system at 1 023 K

The isothermal section of Ag-Ti-Zr ternary system at 1023 K was determined by diffusion triple and electron probe microanalysis. The results indicate that four binary intermetallic phases of AgTi, AgTi2, AgZr and AgZr2 are found in Ag-Ti-Zr ternary system at 1 023 K. AgZr2 and AgTi2 form a continuous solid solution, namely Ag(Ti,Zr)2. Four three-phase regions: AgTi AgZr Ag, AgTi AgZr Ag (Ti, Zr)2, α-Zr β(Ti, Zr) Ag (Ti, Zr) 2 and α-Ti β(Ti, Zr) Ag (Ti, Zr)2 exist in the isothermal section. No ternary compound is observed.     

非线性扩散和变分模型在矢量图像去噪中的应用

分析了非线性扩散、基于整体变分方法的ROF模型以及矢量图像耦合技术的原理,比较了这些扩散、去噪模型的优缺点。根据矢量图像耦合思想将TV流运用到矢量图像扩散中,并参考ROF模型逼近项变分模型的优点,提出了基于非线性扩散、ROF模型和矢量图像耦合原理的改进TV流矢量图像耦合扩散模型,目地是在彩色图像中,去噪同时更好地保留图像轮廓、边缘等重要信息。实验对比分析了改进前后模型的去噪效果,并分析了改进模型下正、逆向扩散在彩色图像去噪中的作用。实验结果表明,改进的矢量图像耦合扩散模型能有效地保持彩色图像中的边缘信息,同时具有良好的去噪性能,且改进模型下,正、逆向扩散的性质在彩色图像去噪工作中仍能保持。     

烷烃在分子筛孔中吸附和扩散的分子模拟

用巨正则系综蒙特卡罗(grand canonical monte carlo,GCMC)和构型偏倚蒙特卡罗(configurational-bias monte carlo,CB- MC)相结合的模拟方法,研究300 K下,烷烃(甲烷、乙烷、丙烷、丁烷)在ISV、MEL型分子筛上的吸附,饱和吸附量的大小顺序为:甲烷>乙烷>丙烷>丁烷。模拟甲烷-乙烷、乙烷-丙烷混合物在分子筛(ISV、MOR、MEL型)中的吸附分离,结果甲烷-丙烷比乙烷-丙烷混合物更易分离。采用分子动力学(molecular dynamics,MD)模拟方法,研究甲烷在MEL、MOR分子筛上的扩散系数,分别为2.76-3.86 m~2·s~(-1)、3.14-13.30 m~2·s~(-1),烷烃在分子筛中的扩散与吸附相关,且扩散系数的大小与分子筛的结构有关。模拟所得的有关吸附扩散性质的数据对于化工生产、研发和设计具有指导意义。