基于图象空间分布的Shading算法

本文首先介绍了基于局部光照模型的串行Shading算法，然后对设计分布式Shading算法所用到的动态任务分配、数据适应性任务分配、任务粒度等因素作了较为详细的论述，并给出了所设计的新的数据适应性任务划分算法，最后给出了所设计的分布式Shading算法的描述和实验结果.     

服装接触舒适性与其织物手感的相关性研究

通过对贴身服用面料的主观接触舒适性和手感的检验,以及对面料客观物理机械性能的测量,综合评价了它们与服装接触舒适性的相关性。研究结果表明,主、客观测得的手感都与接触舒适显著相关,并呈负相关关系。同时建立了4个预测总体接触舒适性的模型:由冷暖感、接触痒感、局部压迫感、接触粘附感及湿冷感等5种舒适感知预测总体接触舒适性;由16项主观手感预测总体接触舒适性;由KES测得的16项客观手感预测总体接触舒适性;以及由主客观测得的显著因子预测总体接触舒适性。     

自主知识产权产品LIP封装

为解决QFN成本较高的问题和进一步提高产品可靠性,华天科技突破了传统思想的束缚,在产品结构的设计上进行了创新。引脚在封装本体内式封装(LIP:Lead In Package)是一种新型的封装形式,它是针对目前QFN(Quad Flat No-lead)在封装高成本问题而重新选择的设计方案。     

Towards Perceptual Simplification of Models with Arbitrary Materials

Real‐time rendering of models with high polygon count is still an important issue in interactive computer graphics. A common way to improve rendering performance is to generate different levels of detail of a model. These are mostly computed using polygonal simplification techniques, which aim to reduce the number of polygons without significant loss of visual fidelity. Most existing algorithms use geometric error bounds, which are well‐suited for silhouette preservation. They ignore the fact that a much more aggressive simplification is possible in low‐contrast areas inside the model. The main contribution of this paper is an efficient simplification algorithm based on the human visual system. The key idea is to move the domain of error computation from image‐space to vertex‐space to avoid a costly per‐pixel comparison. This way the error estimation of a simplification operation can be accelerated significantly. To account for the human vision, we introduce a perceptually based metric depending on the contrast and spatial frequency of the model at a single vertex. Finally, we validate our approach with a user study.     

Generalization of the Lambertian model and implications for machine vision

Lambert's model for diffuse reflection is extensively used in computational vision. It is used explicitly by methods such as shape from shading and photometric stereo, and implicitly by methods such as binocular stereo and motion detection. For several real-world objects, the Lambertian model can prove to be a very inaccurate approximation to the diffuse component. While the brightness of a Lambertian surface is independent of viewing direction, the brightness of a rough diffuse surface increases as the viewer approaches the source direction. A comprehensive model is developed that predicts reflectance from rough diffuse surfaces. The model accounts for complex geometric and radiometric phenomena such as masking, shadowing, and interreflections between points on the surface. Experiments have been conducted on real samples, such as, plaster, clay, sand, and cloth. All these surfaces demonstrate significant deviation from Lambertian behavior. The reflectance measurements obtained are in strong agreement with the reflectance predicted by the proposed model. The paper is concluded with a discussion on the implications of these results for machine vision.     

局部遮挡条件下的光伏阵列防逆流措施选择

对于光伏发电单元,阴影的遮挡可能导致有逆流通过光伏组件,使组件发热损坏。为了防止逆流的产生,通常的做法是在组件回路设置防反二极管。而设置防反二极管可能导致设备体积增大、工程造价增加、汇流设备温度升高等问题。是否设置防反二极管以及防反二极管的设置位置是工程设计中的重点问题。本文以光伏组件的工程应用模型为基础,给出了在局部遮挡条件下逆流的计算方法,包括不设置防反二极管以及防反二极管设置在直流配电柜的逆流计算方法,根据计算结果以及生产厂商提供的光伏组件的参数,来配置防反二极管,优化设备选型。     

基于自耦补偿与谐波屏蔽换流变压器的直流输电系统仿真研究

为揭示自耦补偿与谐波屏蔽(新型)换流变压器电磁暂态瞬变过程,模拟直流输电系统中新型换流变压器网侧与阀侧端口电压、电流的输入、输出特性以及交直流之间的相互 作用,利用仿真软件Matlab分别建立了用于6脉动与12脉动直流输电系统的新型换流变压器仿真模型,并将其应用到直流输电系统动态仿真中。仿真结果表明：新型换流变压器取代传统换流变压器在一定程度上优化了直流输电系统的结构,通过对变压器第三绕组的零阻抗设计及绕组抽头处滤波器参数的合理配置,既能降低换流变压器网侧谐波含量、有效减少谐波与无功对换流变压器的损耗,又改善了换流变压器阀侧的线电压与相电流,有利于换流器可靠换相与正常运行。     

一种光伏系统的多峰值最大功率点跟踪策略

局部阴影条件下,光伏阵列的输出功率-电压(P-U)特性曲线存在多个局部峰值(LMPP)。传统的最大功率点跟踪(MPPT)法可能使系统工作于LMPP,错失真正的全局最大功率点(GMPP)。通过分析局部阴影条件下光伏阵列的输出电流-电压(I-U)特性曲线,提出了将电流控制和扰动观察法(PO)结合的MPPT策略,实现了跟踪GMPP的目标。仿真结果表明该算法比扫描整条P-U曲线法节省了50%的时间,实验验证了其易用性。     

蓝宝石晶体掏棒机内冷式刀柄辅具结构研究

因蓝宝石晶体硬度为莫氏9级,仅次于最硬白金刚石,蓝宝石晶体掏棒加工中会产生很高的切削热量,筒刀和晶体必须进行筒刀内部和外部同时强力冷却,才能保证掏棒加工的稳定性和晶棒质量。所以蓝宝石晶体掏棒加工中要解决的关键技术问题之一,是内冷式刀柄辅具结构的研究、设计、试制、改进和联机使用。     

扁挤压筒过渡曲面建模

为改善铝型材挤压过程中金属流动状况,通过引入流函数法建立基于流曲线的扁挤压筒型腔到模口之间过渡曲面的边界条件;同时采用保角映射方法,描述扁挤压筒型腔及模口处轮廓分别向单位圆的映射关系,构造过渡曲面入口和出口复杂图形的解析函数,解决了复杂三维模型向准三维对称模型的转换问题。两者结合得到过渡曲面上各点的流线方程,完成对过渡曲面的数学描述。为验证新构建曲面的合理性,对一矩形壁板成形过程进行模拟。结果表明：流线型过渡曲面有利于金属流动,并且有利于降低型腔面上的法向压力,可减少磨损、提高模具寿命。