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 实验研究了超低碳Ti IF钢性能和析出相,结果表明：超低碳Ti IF钢具有低的屈强比、高塑性、高应变硬化性能和高成形性能,其屈强比约为0.5,抗拉强度为310 MPa,屈服强度为155 MPa,伸长率47%～50%,应变硬化指数n值为0.26～0.28,塑性应变比r值均在2.0左右,最高r值达2.25。退火织构特征均表现为较强的γ纤维织构和较弱的α纤维织构,γ纤维织构主要为{111}<110>和{111}<112>,最强点在{111}<110>处,有利的{111}取向织构使Ti IF钢具有优异的深冲性能。在超低碳钢中加入微量的Ti,形成碳化物、氮化物和氮碳化物,可以固定间隙原子（如C、N原子）,获得无间隙原子钢,同时,适量固溶Ti,能显著提高钢的深冲性能。析出相主要有Ti(N,C)及TiC ,Ti2CS, Ti3S4及很少量的AlN,而粗大稀疏的Ti2CS等析出相对晶界的钉扎力小,相应的促进了{111}再结晶织构的发展,从而获得较高的r值。     

基于三维实时渲染技术的虚拟火灾训练系统设计

基于三维实时渲染技术的火灾训练系统包括:建筑三维地图构造和显示及与用户的交互,火灾的模拟,指导逃生和救援决策。探讨了利用实时三维绘制技术、人工智能和模式识别的相关算法结合火灾的危害模型建立虚拟火灾训练系统的途径。通过研究提出了采用虚拟现实来创建火灾和逃生救援的软件系统的设计方案,以及将OpenGL与DirectX相结合在Windows平台上实现基于C/S结构下的虚拟火灾训练系统的技术。     

适于点绘制的层次多分辨率建模方法的研究

在基于点的图形绘制技术中,需要记录大量的场景采样点,如何有效地组织这些数据是实现快速高效绘制的关键问题之一。论文研究了适于点绘制的有效数据组织——层次多分辨率建模,分析了三种常用的模型结构及其构建算法,讨论了模型结构中的层次细节选择方案,提出了一种层次细节的顺序选择方法,实验证明这些方法是有效的。     

最小二乘法重构r重平移不变子空间采样的研究

该文根据r重平移不变子空间采样模型,提出了一种基于最小二乘法的r重平移不变子空间采样重构方法,并且获得了重构滤波器的频域表达式;同时利用Hilbert空间投影理论分析了重构误差;最后,以调幅信号为例,验证了最小二乘法重构r重平移不变子空间采样的可行性。     

Corrosion of UO2 and ThO2: A quantum-mechanical investigation

The addition of Th to U-based fuels increases resistance to corrosion due to differences in redox-chemistry and electronic properties between UO₂ and ThO₂. Quantum-mechanical techniques were used to calculate surface energy trends for ThO₂, resulting in (1 1 1) < (1 1 0) < (1 0 0). Adsorption energy trends were calculated for water and oxygen on the stable (1 1 1) surface of UO₂ and ThO₂, and the effect of model set-up on these trends was evaluated. Molecular water is more stable than dissociated water on both binary oxides. Oxidation rates for atomic oxygen interacting with defect-free UO₂(1 1 1) were calculated to be extremely slow if no water is present, but nearly instantaneous if water is present. The semi-conducting nature of UO₂ is found to enhance the adsorption of oxygen in the presence of water through changes in near-surface electronic structure; the same effect is not observed on the insulating surface of ThO₂.     

基于打包索引纹理的大规模数据体绘制算法

针对大规模数据体绘制效率低下的问题,提出一种算法：对体数据进行纹理分块打包,移除空数据块,并创建数据块的索引数据,绘制时通过索引访问打包后的纹理实现大规模数据完全载入显存,同时在索引中标记空数据及高密度数据块的位置,绘制前生成其有效的立方体数据表达,结合早期光线终止与空域跳过等加速技术,有效地实现了大规模的体数据的实时绘制,同时保证了结果图像的质量。     

一种改进求交的自适应光线投射体绘制算法

光线投射算法是体绘制技术中的一种重要算法,但其自身存在采样效率低和绘制速度慢等问题。为了提高光线投射算法的绘制速度,本文提出了一种改进求交的自适应光线投射体绘制算法,算法采用一种快速求交方法和自适应采样来提高体绘制速度,试验结果表明该算法能在基本不影响图像质量的同时提高算法的速度。     

Ion beam analysis of rare earth nitride thin films

We report compositional measurements on highly disordered GdN, DyN, ErN and SmN thin films, grown using ion-assisted deposition and capped with GaN AlN and Al, grown using the same technique. Ion beam analysis technique of RBS, PIXE and nuclear reaction analysis (NRA) were used to determine the composition of the capped films ex situ, and show that GaN and AlN protects the GdN, DyN and SmN films from oxidation over a timescale of at least a few days. NRA depth profiles indicate that oxygen is incorporated into the films during deposition and is located at the GaN/GdN interface. The ion beam analysis measurements showed that stoichiometric ratios can be obtained and oxygen impurities are significantly reduced by varying the film deposition parameters. The successful protection of the rare earth (RE) nitride films from oxidation allows for a reliable analysis of the RE films in the as-deposited state.     

Effect of oxygen on gamma irradiation of polypropylenes studied by positron annihilation spectroscopy

The aim of this paper is to study the effect of oxygen on the microstructure of PP irradiated by gamma ray. The released gases from the sample in irradiation process were measured by gas chromatography. The results showed that the hydrogen release from the irradiated PP is independent on the irradiation atmosphere. It is only dependent on the irradiation dose that could be interpreted by a simple model. The microstructure of PP samples irradiated under different atmospheres is studied by positron annihilation spectroscopy. It is found that there are two sub-peaks in free volume distribution of PP irradiated under helium, while only one peak in the distribution of PP irradiated under air. It is the direct evidence to the argument that the new voids are formed in the irradiation process under inert gas and the oxygen may induce the voids to merge together. The influence of oxygen on the crystalline of PP irradiated by gamma is also discussed.     

Measurement of collision integral cross-sections of double-photon Compton effect using a single gamma ray detector: A response matrix approach

The collision integral cross-sections of double-photon Compton process are measured experimentally for 662 keV incident gamma photons. The measurements are successfully carried out using a single gamma ray detector, and do not require the complicated slow-fast coincidence technique used till now for observing this higher order quantum electrodynamics (QED) process. The energy spectra of one of the two final photons, originating in this process, in direction of the gamma ray detector are observed as a long tail to the single-photon Compton line on lower side of the full energy peak in the observed spectra. An inverse response matrix converts the observed pulse-height distribution of a NaI(Tl) scintillation detector to a true photon spectrum. This also results in extraction of events originating from double-photon Compton interactions. The present measured values of collision integral cross-section, although of same magnitude, deviate from the corresponding values obtained from the theory. In view of the magnitude of deviations, in addition to small value of probability of occurrence of this process, the agreement of measured values with theory is reasonably acceptable.