不同浓度Cu掺杂SnO2材料电学和力学性质的研究

为研究Cu掺入对SnO_2性能的影响,本文采用密度泛函理论和平面波赝势法,建立了未掺杂SnO_2和不同比例Cu掺杂的SnO_2晶胞模型,对Sn_(1-x)Cu_xO_2(x=0、0.083、0.125、0.167、0.25、0.5)超晶胞体系进行优化计算、能量计算和弹性模量计算,得到晶格常数、弹性模量、电荷分布、能带结构和态密度图.研究表明:掺杂能够使得材料的弹性模量大幅减小,对应的硬化函数值降低,易于材料加工;在电性质方面,掺杂后,材料均属于直接带隙半导体材料.当x0.25时,由于掺杂浓度过高使得晶格发生畸变,电性质与未掺杂情况类似;当x0.25时,随着掺杂浓度的降低,导带收缩加剧,局域性增强,禁带宽度变窄,使得电子从价带受激跃迁所需能量降低,故掺杂后材料表现出半金属性,导电性增强.     

超声作用下刚性壁面附近的双气泡脉动

在实际应用时,空化泡可能位于刚性壁附近。对刚性壁附近的空化泡脉动进行研究有利于更好地利用声空化。文章研究了刚性壁附近双气泡的动力学规律。研究结果表明,当两气泡与刚性壁距离相同时,气泡与壁之间的距离越大,刚性壁对辐射声波的反射越小,气泡脉动时能够达到的最大半径与最小半径的比值(即压缩比)也越大。若改变单个气泡与刚性壁的距离,则当两个气泡距离接近时,位置固定的气泡压缩比会减小。增大单个气泡的平衡半径,会使得两气泡脉动时的压缩比变小。此外,文章还对两气泡间距固定情况下,气泡压缩比与两气泡中心连线和壁面所成夹角之间的关系进行了讨论。     

讲好离散数学的第一次课

离散数学是计算机专业的核心基础课,文章针对离散数学内容散、概念多且容易被认为枯燥无味等特点,结合笔者多年的教学经验,分析并提出通过讲好离散数学第一次课提高教学效果的方法,该方法包含笔者总结的离散数学的重要性、离散数学的学习方法和经过加工的教学内容。实践表明该方法效果较好,对青年教师有一定的指导作用。     

一种基于XML的非线性编辑初剪辑技术研究

随着计算机信息技术的快速发展,非线性编辑已成为影视业界节目制播主要的工作模式.目前虽然通过数字化大大提升了初剪辑的工作效率,但由于仍采用现有的剪辑工作流程,时间成本消耗偏高.通过分析非线性编辑的需求,将XML架构应用在初剪辑工作中,建立起一套基于XML初剪方式的语法,以提高初剪辑工作效率及节目品质.     

The evaluation of speckle contrast with variable speckle generator

Abstract— While laser projection has many advantages, there is a problem with speckle patterns generated as a result of interference of the laser beam and results in bad effects to observers. In 2010, a variable speckle generator, which produces an angular shift of incident light to the screen and generates variable speckle patterns, was suggested. In this study, the performance of a variable speckle generator by using a volume phase holographic beam shaper and scanning mirror was investigated in detail by evaluating both the objective and subjective speckle contrast. The morphology of the speckle pattern was also investigated when the variable speckle generator was activated. With a scanning VPH beam shaper, the objective speckle was effectively reduced because each point of the VPH beam shaper generated different speckle patterns and coherency among each pattern disappeared by using the scan process. On the other hand, subjective speckle was also dramatically reduced by changing the incident angle on the screen, which resulted in generating variable subjective speckle. It was also shown that the speckle reduction rate by using a variable speckle generator did not depend on the coherent length of a laser by evaluating the normalized speckle contrast against the angular shift on the screen.     

Improving responsiveness of soft aperiodic tasks using proportional slack time

In a real-time system with both hard real-time periodic jobs and soft real-time aperiodic jobs, it is important to guarantee that the deadline of each periodic job is met, as well as to provide a fast response time for each aperiodic job. We propose an algorithm, called Proportional Slack Reserve (PSR), that produces an efficient schedule for such an environment. For every execution unit of a periodic job, the PSR algorithm reserves time which can be used for execution of aperiodic jobs. If reserved time is not available, the algorithm assigns a deadline to an aperiodic job for achieving better responsiveness of aperiodic jobs. The proposed algorithm can fully utilize processing power while meeting all deadlines of periodic jobs. It can also easily reclaim the time unused by the periodic job. We analytically show that for each aperiodic job, the response time in a PSR schedule is no longer than that in a TBS schedule, which is known to be efficient for servicing aperiodic jobs. We also present simulation results in which the response time of PSR is significantly improved over that of TBS, and moreover the performance of PSR compares favorably with TB(N) considering scheduling overhead.     

大型点焊机器人特种作业程序镜像修正技术研究

以不锈钢列车车体点焊机器人作业路径规划编程为研究对象,针对车体对称部件,如左右侧墙点焊的的问题,提出点焊路径规划编程镜像的方法,引入X,Y,Z主轴以及龙门架E1轴系统偏差的修正和A,B,C旋转轴镜像处理的方法来调整焊钳位姿同时对焊接路径点焊位置修正镜像,并依据镜像规则在Windows环境下使用VC++语言开发了镜像程序生成器.通过仿真结果表明,该软件生成的镜像程序可与作业基准点完美衔接,最后在车间复杂环境下的实际运行验证了该方法的有效性.     

Using a Visual Attention Model to Improve Gaze Tracking Systems in Interactive 3D Applications

This paper introduces the use of a visual attention model to improve the accuracy of gaze tracking systems. Visual attention models simulate the selective attention part of the human visual system. For instance, in a bottom‐up approach, a saliency map is defined for the image and gives an attention weight to every pixel of the image as a function of its colour, edge or intensity. Our algorithm uses an uncertainty window, defined by the gaze tracker accuracy, and located around the gaze point given by the tracker. Then, using a visual attention model, it searches for the most salient points, or objects, located inside this uncertainty window, and determines a novel, and hopefully, better gaze point. This combination of a gaze tracker together with a visual attention model is considered as the main contribution of the paper. We demonstrate the promising results of our method by presenting two experiments conducted in two different contexts: (1) a free exploration of a visually rich 3D virtual environment without a specific task, and (2) a video game based on gaze tracking involving a selection task. Our approach can be used to improve real‐time gaze tracking systems in many interactive 3D applications such as video games or virtual reality applications. The use of a visual attention model can be adapted to any gaze tracker and the visual attention model can also be adapted to the application in which it is used.     

一种基于图像块的Legendre矩高精度快速算法

针对图像的Legendre正交矩计算量大和矩值求解过程中存在离散近似误差等问题,提出一种新的高精度快速计算图像Legendre矩方法.文中首先提出一种最大块优先分块策略,然后在此基础上,根据图像像素灰度值的取值特征将图像进行分块表示,以每个图像块为单位计算图像的Legendre矩.实验结果表明,与现有的快速算法相比,文中方法在保证矩值高精确的前提下,有效地减少了算术运算的次数,降低了计算复杂度,具有较快的计算速度.     

基于单元树结构的广度优先P2P搜索算法

提出基于单元树结构的广度优先搜索算法UTBFS。将单元树结构生成算法与广度优先算法相结合,阐述UTBFS的实现思路,对其时间复杂度、空间复杂度、可行性、优越性进行分析。实验仿真结果显示,相比于传统的广度优先搜索算法和随机广度优先搜索算法,UTBFS减少了需要转发消息的邻居节点个数和冗余消息,因此性能更优。