HfC改性炭/炭复合材料的烧蚀性能

采用金属盐溶液浸渍-TCVI(Thermal Gradient Chemical Vapor Infiltration)法制备了HfC改性炭/炭复合材料.通过氧-乙炔烧蚀实验测试了不同含量HfC改性炭/炭复合材料的抗烧蚀性能;利用DSC-TG,SEM,XRD分析了HfC的形成过程、材料烧蚀前后的微观形貌及物相组成.结果表明:HfC的加入降低了炭/炭复合材料的线烧蚀率,其中HfC含量为6.5%(质量分数,下同)的炭/炭复合材料的线烧蚀率最低.HfC具有抑制氧化及弥补缺陷的作用,从而降低了炭/炭复合材料的热化学烧蚀和机械剥蚀.     

TiO2纳米管阵列的热稳定性及生物活性的研究

通过电化学阳极氧化法，在纯钛片表面制备得到TiO2纳米管阵列。研究了TiO2纳米管阵列的热稳定性，并通过模拟体液浸泡研究了其生物活性。采用扫描电镜（SEM）和X射线衍射（XRD）分别对纳米管阵列的形貌和物相进行表征。结果表明，当热处理温度为300℃时，TiO2纳米管由无定形向锐钛型转变，温度升到500℃时转变为金红石型，升到600℃时TiO2纳米管阵列出现坍塌，700℃热处理时其形貌完全被破坏。生物活性研究表明，具有TiO2纳米管阵列的钛片经氢氧化钠溶液活化后具有良好的生物活性，能在模拟体液中诱导生成磷灰石。     

Crystal and magnetic structures of Laves phase compound NdCo2 in the temperature range between 9 and 300 K

The crystal and magnetic structures of the Laves phase compound NdCo₂ in the temperature range from 9 to 300 K are determined by Rietveld refinement technique, using high-resolution neutron powder diffraction data. The compound crystallizes in space group above the magnetic ordering temperature T_C (≈100 K), in space group I4₁/amd below T_C and in space group Imma below the tetragonal–orthorhombic structural/magnetic transitions at T_M ≈ 42 K. The assignment of the space groups to the crystal structures of NdCo₂ in different temperature ranges complies with the reported Mössbauer studies. Detailed information of the crystal and magnetic structures of NdCo₂ at different temperatures are reported.     

用天然石英粉制备氮氧化硅粉末

以天然石英粉为原料，先进行活化预处理，然后在１３５０℃左右进行碳热还原氮化，制备了氮氧化硅粉末。实验结果表明：氮化过程中ＳｉＯ２的转化率及产物中氮氧化硅（Ｓｉ２Ｎ２Ｏ）的含量与ＳｉＯ２的活化程度、氮化温度及添加剂等因素有关，其中氮化温度以１３５０℃为佳；随着ＳｉＯ２活化程度的提高，其转化率也提高；添加少量的ＳｒＯ，可以进一步提高ＳｉＯ２的转化率。此外，还分析了ＳｉＯＣＮ系统中气体分压对Ｓｉ２Ｎ２Ｏ形成的影响。     

Hybrid immune algorithm based on greedy algorithm and delete-cross operator for solving TSP

This paper first introduces the fundamental principles of immune algorithm (IA), greedy algorithm (GA) and delete-cross operator (DO). Based on these basic algorithms, a hybrid immune algorithm (HIA) is constructed to solve the traveling salesman problem (TSP). HIA employs GA to initialize the routes of TSP and utilizes DO to delete routes of crossover. With dynamic mutation operator (DMO) adopted to improve searching precision, this proposed algorithm can increase the likelihood of global optimum after the hybridization. Experimental results demonstrate that the HIA algorithm is able to yield a better solution than that of other algorithms, which also takes less computation time.     

视景建模中树木纹理图像的随机变形网格方法

目的 视景建模中,采用“公告板”贴图法对同树种不同个体树建模时,需生成各种形态各异的树木纹理图像,为此提出一种新的生成树木纹理图像的随机变形网格方法。方法 首先将树木的原始纹理图像进行网格划分,再对网格顶点进行随机变形,最后将生成的不规则网格中的图像映射到新图像中相应的规则网格上,得到变形后的纹理图像。结果 应用随机参数控制树木图像的变形,模拟出成长环境因素对树木形态的影响。本文方法比采集多幅个体树图像贴图方法更简便,容易实现;比用同一幅图像进行多个个体贴图的视觉效果更真实。结论 本文方法生成的树木纹理图像应用于“公告板”贴图时,在视景模型中能较好地模拟出同一树种的多个个体树情景。该方法基于图像的局部变形,仍然保持原始图像内容的整体基本形态和内部结构的连续性,因此,同样适用于其他不规则形状的自然景物(如山峦、河流、海浪等)的图像处理。     

S698 T处理器的RTEMS移植和应用程序开发

一个简单的星载计算机模型由一个模拟真实卫星的嵌入式系统和系统运行所必需的数据集合组成,该数据集合由PC机上运行的程序生成,模拟真实卫星的运行环境。为了构建这个模型,首先要完成以SPARC V8架构处理器S698 T为基础的 RTEMS操作系统移植,然后分别在S698 T端和 PC端开发对应的应用程序,讨论构建嵌入式系统的主要步骤和需要注意的问题。     

A fast face detection architecture for auto-focus in smart-phones and digital cameras一个快速的人脸检测架构用于智能手机和数码相机的自动对焦

Auto-focus is very important for capturing sharp human face centered images in digital and smart phone cameras. With the development of image sensor technology, these cameras support more and more highresolution images to be processed. Currently it is difficult to support fast auto-focus at low power consumption on high-resolution images. This work proposes an efficient architecture for an AdaBoost-based face-priority auto-focus. The architecture supports block-based integral image computation to improve the processing speed on high-resolution images; meanwhile, it is reconfigurable so that it enables the sub-window adaptive cascade classification, which greatly improves the processing speed and reduces power consumption. Experimental results show that 96% detection rate in average and 58 fps (frame per second) detection speed are achieved for the 1080p (1920×1080) images. Compared with the state-of-the-art work, the detection speed is greatly improved and power consumption is largely reduced.