Ti扩散铌酸锂光波导特性的热固定技术

在Ti扩散铌酸锂光波导中,因光致折变效应而导致光波导特性漂移.在光波相干性的导波光学器件中,光致折变效应的影响尤为严重.本文报道了稳定光致折变效应的热固定技术实验结果;并提出在光波导特性的热固定过程中,不是H~+离子起主导作用这一看法.     

纯热传导冷却产生软X射线激光

本文通过n_e=1×10~(19)cm~(-3)的热等离子体,在纯热传导冷却机制下的计算,得到了等离子体温度的时空变化,并运用碰撞-辐射模型计算了在这种条件下,类锂铝离子4f-3d,5f-3d跃迁的增益系数,计算表明:只要有合适的初始条件,用纯热传导冷却机制,也能产生软X射线激光增益.     

阿尔芬波加热托卡马克等离子体的能量平衡问题

本文用“剖面不变性”确定等效电子热导系数,研究了TCA装置上阿尔芬波加热的能量平衡,结果与实验符合很好。证明本文所用的方法对不同装置、不同加热方式都适用。     

The rotational anisotropies in the ferromagnetism/antiferromagnetism 1/ antiferromagnetism 2 exchange bias structures

The rotational anisotropies in the exchange bias structures of ferromagnetism/antiferromagnetism 1/antiferromagnetism 2 are studied in this paper. Based on the model, in which the antiferromagnetism is treated with an Ising mean field theory and the rotational anisotropy is assumed to be related to the field created by the moment induced on the antiferromagnetic layer next to the ferromagnetic layer, we can explain why in experiments for ferromagnetism (FM)/antiferromagntism 1 (AFM1)/antiferromagnetism 2 (AFM2) systems the thickness-dependent rotational anisotropy value is non-monotonic, i.e. it reaches a minimum for this system at a specific thickness of the first antiferromagnetic layer and exhibits oscillatory behaviour. In addition, we find that the temperature-dependent rotational anisotropy value is in good agreement with the experimental result.     

低温太阳热能与化学链燃烧相结合控制CO2分离动力系统

本文探索并提出控制CO2分离的低温太阳热能与清洁合成燃料甲醇-三氧化二铁化学链燃烧相结合的新颖能源动力系统。基于图象(?)分析方法,明确地指出甲醇化学链燃烧能量释放过程燃烧堋损失减小和低温太阳热能品位提升的机理。从能源有效利用和环境相容出发,研究和揭示化学链燃烧与太阳能有机整合共同减小CO2分离能耗的特性规律。相比不分离常规联合循环,新系统(?)效率提高约6．2个百分点;与分离CO2的联合循环相比,新系统媚效率提高约14．2个百分点。同时,低温太阳热能热转功效率可达到22．5％。     

可重复使用飞行器热走廊物理建模研究

对再入热走廊的物理含义进行了定义分析,为使防热层温度不超过热防护系统所允许使用的极限温度,可重复使用飞行器的飞行轨道必须在再入走廊热之内。建立了可重复使用飞行器再入热走廊的物理模型,给出该物理模型下热走廊的控制方程和求解方法。通过对航天飞机轨道器典型位置的再入热走廊与传统方法的验证分析,说明本文建立的可重复使用飞行器再入热走廊物理模型和求解方法是正确的,同时探讨了表面材料承受温度和发射系数对热走廊的影响规律。     

Synthesis of In<Subscript>2</Subscript>O<Subscript>3</Subscript>nanoparticles by thermal decomposition of a citrate gel precursor

This paper describes the synthesis of indium oxide by a modified sol–gel method, and the study of thermal decomposition of the metal complex in air. The characterization of the intermediate as well as the final compounds was carried out by thermogravimetry, differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and small angle X-ray scattering. The results show that the indium complex decomposes to In₂O₃ with the formation of an intermediate compound. Nanoparticles of cubic In₂O₃ with crystallite sizes in the nanosize range were formed after calcination at temperatures up to 900°C. Calcined materials are characterized by a polydisperse distribution of spherical particles with sharp and smooth surfaces.This revised version was published online in August 2005 with a corrected issue number.     

碳纳米管包裹的硅纳米线复合结构的热稳定性研究

采用经典分子动力学方法模拟一定直径[111]晶向的硅纳米线填充不同扶手椅型单壁碳纳米管复合结构的加热过程, 通过可视化和能量分析的方法判断复合结构中硅纳米线和碳纳米管的热稳定性. 通过讨论碳纳米管的空间限制作用和分子间相互作用力的关系, 对碳纳米管和硅纳米线的热稳定性变化进行初步解释. 研究发现碳纳米管中硅纳米线的热稳定性和碳纳米管的直径关系密切: 当管径较小时, 硅纳米线的热稳定性有所提高, 当管径增大到一定大小时, 硅纳米线的热稳定性会突然显著地下降, 直到硅纳米线与管壁不存在分子间相互作用力, 硅纳米线的热稳定性才会恢复. 而硅纳米线填充到碳纳米管中对碳纳米管的热稳定性有着明显的降低作用.     

Influence of the Grain Boundaries on the Heat Transfer in Laser Ceramics

Grain boundaries play a key role in determining several key properties of polycrystalline laser ceramics. Heat transfer measurements at low temperature constitute a good tool to probe grain boundaries. We review the results of heat transfer measurements in polycrystalline Y₃Al₅O₁₂ garnets as well as Y₂O₃ and Lu₂O₃ sesquioxide materials obtained by self-energy-driven sintering of nano-particles. The average phonon mean free path in Y₃Al₅O₁₂ was found to be significantly larger than the average grain size and to scale with temperature as T ⁻² at low temperature. Existing models describing the interaction between phonons and grain boundaries are reviewed. Correct temperature dependence of the mean free path and order of magnitude of scattering rates were found by assuming the existence of a grain boundary layer having acoustic properties different from those of the bulk. A different temperature dependence of phonon mean free path was found for the sesquioxides and was ascribed to the stronger elastic anisotropy of these materials. The thermal resistance associated to the grain boundaries of laser ceramics was found to be lower than in other dense polycrystalline ceramic materials reported in the literature.     

Diffusion and transport phenomena in a collisional magnetoplasma having both streaming and temperature anisotropy: Collisional kinetics

Boltzmann-transport equation is analytically solved for two-component magnetoplasma using Chapman-Enskog analysis to include collisional diffusion transport having anisotropies in both streaming velocity and temperature components. The modified collisional integrals are analytically solved with flux integrals and perturbed kinetic equation to arrive at drift diffusion velocity and resulting transport coefficients which are markedly affected by both streaming and temperature anisotropy. The early isotropic results are recovered in the limit V ₀ = 0 and T _‖ = T _⊥ which reduce to eqs (11.30) and (11.31) of [1] and eqs (2.7) and (2.13) of [2]. The electrical resistivity (η_⊥) diminishes sharply in fusion temperature limit kT _⊥ = 1 keV. The shape of the curves for both electrical resistivity and thermal conductivity is rectangular hyperbolic. However, for low thermal ratio (T _‖/T _⊥ < 1), the curves are raised up and for high thermal ratio (T _‖/T _⊥ > 1), they are lowered down the isotropic case (T _‖/T _⊥ > 1), showing comparatively diminished magnitudes of the quantities.