C/Cu(Fe)复合材料制备工艺及性能研究

利用三步电沉积法制备C／Cu（Fe）复合材料预制丝，将预制丝缠绕成毛坯，采用真空热压法制备C／Cu（Fe）复合材料．研究表明，真空热压工艺对复合材料力学性能有很大影响，通过力学性能试验和对拉伸断口形貌的分析，得出了制备C／Cu（Fe）复合材料的最佳工艺．     

G.729A+B语音编解码在新一代定点DSPs上的实现

文章介绍了ITU-TG．729A算法与ITU-TG．729B算法配合使用的语音编解码方案，并讨论了其在TI公司最新一代定点数字信号处理器(DSPs)TMS320C6416上实现的关键技术。G．729A是G.729编码器的简化版本，G．729B是带VAD(活动话音检测)的静音压缩算法。两者结合可以有效地降低码率，同时保持很好的合成语音质量。     

C/C复合材料Mo - Si-N系抗氧化涂层成分优化

以Mo粉和Si粉为原始粉末,采用熔浆法在C/C复合材料表面原位合成了Si3N4-MoSi2/Si-SiC(MSN)系多层抗氧化涂层,借助扫描电镜和X射线衍射仪等分析手段对涂层的相组成和微观组织进行表征,并对涂层的抗氧化性能进行了初步研究.结果表明:Si浆料中添加适量Al可有效地阻止液态Si渗入C/C基材内部,3%Al-Si涂层具有最好的阻止Si渗入作用;Al含量超过3%时,Si的渗入程度随Al含量的增加而加剧;涂层中MoSi2的理论含量超过50%时,MSN-C/C复合材料1 400℃的抗氧化性能随MoSi2含量的增加而显著下降;MSN30-C/C和MSN40-C/C复合材料均在1 200～1 400℃表现出相近的抗氧化能力,但只有MSN30-C/C复合材料表现出抗1 450℃氧化的能力.     

Design feasibility study of a divertor component reinforced with fibrous metal matrix composite laminate

Fibrous metal matrix composites possess advanced mechanical properties compared to conventional alloys. It is expected that the application of these composites to a divertor component will enhance the structural reliability. A possible design concept would be a system consisting of tungsten armour, copper composite interlayer and copper heat sink where the composite interlayer is locally inserted into the highly stressed domain near the bond interface. For assessment of the design feasibility of the composite divertor concept, a non-linear multi-scale finite element analysis was performed. To this end, a micro-mechanics algorithm was implemented into a finite element code. A reactor-relevant heat flux load was assumed. Focus was placed on the evolution of stress state, plastic deformation and ductile damage on both macro- and microscopic scales. The structural response of the component and the micro-scale stress evolution of the composite laminate were investigated.     

Structure study on the thermoelectric materials CexCo4Sb12 (x = 0.5, 1.0) by neutron diffraction

In order to understand the relationship between crystal structure and thermoelectric properties, the neutron diffraction patterns of the thermoelectric materials with the nominal composition Ce_xCo₄Sb₁₂ (x = 0.5, 1.0) were measured at room temperature, the data were fitted by the Rietveld profile refinement method using the Fullprof2k program. It is found that the sample Ce_0.5Co₄Sb₁₂ is composed of two phases, its major phase is CoSb₃ with skutterudite-structure and the Ce atom is not incorporated into the lattice, the impurity is monoclinic CoSb₂. In the case of Ce_1.0Co₄Sb₁₂, the major phase is filled skutterudite, about 10% of the 2a site is occupied by Ce atom, the second phase is monoclinic CoSb₂.     

基于80C196MC的交流牵引变频调速控制系统

本文介绍了一种以新型智能功率模块IPM，SPWM专用控制芯片80C196MC为基础构成的交流牵引变频调速控制系统，介绍了系统的控制原理及软硬件的设计方案。     

Light emission from carbon-based materials under ITER relevant thermal shock loads

Light emission from carbon-based materials (fine grain graphite, CFC and silicon doped CFC) was observed during ITER relevant thermal shock loads by means of in situ optical diagnostics. The light emission which corresponds to particle release clearly indicated different particle release processes in the three materials. The differences were also found in the initiation temperatures of particle release and the surface morphology of the loaded areas. These results are related to the thermal stress in bulk materials. In addition to particle release, vapor cloud formation caused by thermal shock loads were observed as CII lines and lines from the C₂ Swan system. No Si lines but lines from SiC₂ molecules (Merrill-Sanford bands) were observed in Si doped CFC. This indicates that atomic silicon is not released under ITER relevant thermal shock loads.     

Uranium oxide weathering: spectroscopy and kinetics

Particles of UO_2+x (x≅0.16 ± 0.06) exposed to the atmosphere react by oxidation and formation of complexes (hydrates, hydroxides and carbonates). Surface reactions alter and erode the UO₂ particles. This paper outlines results for measurements of oxidation rates on uranium oxide particles using in situ photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Phosphorescence spectra observed during oxidation of UO_2+x were attributed to U(VI) in uranyl-type coordination and in octahedral coordination. Uranyl-type spectra formed during wet oxidation of UO_2+x, and U(VI) octahedral spectra formed during dry oxidation of UO_2+x. The uranyl-type species, although more stable, is more kinetically labile for vacuum reduction than is the octahedral U(VI). Oxidation of U(IV) species are diffusion controlled. Vacuum reduction of uranyl U(VI) in UO₃ follows a field-enhanced cationic diffusion rate law, while re-oxidation follows a diffusion rate law. Post-oxidation core and valence band XPS and SIMS measurements provided qualitative and quantitative measures of uranium oxidation states near uranium oxide surfaces.