基于力触觉手柄的虚拟环境力反馈交互系统稳定性分析

基于力触觉手柄的虚拟环境(VE)力反馈系统在人机交互领域得到广泛应用,稳定性是系统正常工作的前提。首先将力反馈设备、虚拟交互环境以及操作者作为独立模块单独建模,再基于阻抗再现方法建立力反馈交互系统闭环控制模型,并利用赫尔维兹判据推导了系统稳定的条件,利用频率响应函数分析了刚度和阻尼、零阶保持器的信号保持时间间隔以及操作者阻抗对系统稳定性的影响,给出了虚拟刚度、虚拟阻尼以及操作者阻抗等影响因素的临界稳定条件。利用研制的力反馈触觉手柄构建了实验系统并进行了实验研究,针对不同的力反馈频率和不同的阻抗分析了不同条件下的系统稳定性。实验结果证明了理论分析的正确性。     

An ideal host-guest system to accomplish high-performance greenish yellow and hybrid white organic light-emitting diodes

Greenish yellow organic light-emitting diodes (GYOLEDs) have steadily attracted researcher's attention since they are important to our life. However, their performance significantly lags behind compared with the three primary colors based OLEDs. Herein, for the first time, an ideal host-guest system has been demonstrated to accomplish high-performance phosphorescent GYOLEDs, where the guest concentration is as low as 2%. The GYOLED exhibits a forward-viewing power efficiency of 57.0 lm/W at 1000 cd/m², which is the highest among GYOLEDs. Besides, extremely low efficiency roll-off and voltages are achieved. The origin of the high performance is unveiled and it is found that the combined mechanisms of host-guest energy transfer and direct exciton formation on the guest are effective to furnish the greenish yellow emission. Then, by dint of this ideal host-guest system, a simplified but high-performance hybrid white OLED (WOLED) has been developed. The WOLED can exhibit an ultrahigh color rendering index (CRI) of 92, a maximum total efficiency of 27.5 lm/W and a low turn-on voltage of 2.5 V (1 cd/m²), unlocking a novel avenue to simultaneously achieve simplified structure, ultrahigh CRI (>90), high efficiency and low voltage.     

A scalable architecture for geometric correction of multi-projector display systems

Multi-projector displays allow the realization of large and immersive projection environments by allowing the tiling of projections from multiple projectors. Such tiled displays require real time geometrical warping of the content that is being projected from each projector. This geometrical warping is a computationally intensive operation and is typically applied using high-end graphics processing units (GPUs) that are able to process a defined number of projector channels. Furthermore, this limits the applicability of such multi-projector display systems only to the content that is being generated using desktop based systems. In this paper we propose a platform independent FPGA based scalable hardware architecture for geometric correction of projected content that allows addition of each projector channel at a fractional increase in logic area. The proposed scheme provides real time correction of HD quality video streams and thus enables the use of this technology for embedded and standalone devices.     

Yield and Quality Characteristics of Rendered Chicken Oil for Biodiesel Production

Whole dead poultry birds obtained from commercial layer farms were assessed for fat in the whole carcass and then dry rendered in three different rendering regimens T₁, T₂ and T₃ (temperature = 120, 130 and 140 °C and shell pressure = 1, 2 and 3 kg/cm² respectively) and the effect on the yield and quality of the rendered chicken oil were studied. The overall fat percentage of the whole dead poultry carcass was 14.55 ± 0.17 % and the fat content of ‘greaves’ was 14.49 ± 0.38 %. In the dry batch rendering trials, the mean overall fat recovery was 24.46 ± 1.19, 26.78 ± 3.14 and 22.42 ± 2.32 % and the overall fat yield was 3.52 ± 1.72, 3.84 ± 0.44 and 3.22 ± 0.33 % of the carcass weight in T₁, T₂ and T₃ respectively. Solvent extraction of fat could recover 96.10 ± 0.14 % of fat from ‘greaves’ which was significantly higher than the mechanical centrifugation method. Among the quality characteristics of the rendered chicken oil (RCO), moisture content ranged from 0.61 % (T₂) to 1.09 % (T₁) and the mean specific gravity was 0.91 at 30 °C. The FFA values of RCO obtained from the T₃ rendering regimen were significantly (p < 0.05) higher than the FFA values of T₂ and T₁. The mean acid value, iodine number, peroxide value, saponification value and unsaponifiable matter present in RCO showed no significant difference. The fatty acid profile and calorific values were studied. The RCO was converted to biodiesel by transesterification and the physico-chemical properties of the biodiesel were studied and compared with the Indian biodiesel specification.     

建筑节能材料检测中的几点问题与探讨

本文针对检测过程中出现的一些问题,从试样制备、胶粘剂和抹面胶浆、现场锚栓拉拔以及导热系数四个方面进行了分析,提出了自己的观点和解决问题的建议.     

MEMBRANE BIOREACTORS AND CONSTRUCTED WETLANDS FOR TREATMENT OF RENDERING PLANT WASTEWATER

The performance of a novel industrial membrane bioreactor (MBR) comprising denitrification, nitrification and ultrafiltration for the secondary treatment of primary treated animal rendering wastewater has been compared with an experimental, low-cost and novel vertical-flow constructed wetland planted with Typha latifolia L. (Reedmace or Broad-leaved Cattail). The process wastewater followed pre-treatment by dissolved air flotation (DAF). The mean DAF effluent gave highly variable chemical oxygen demand (COD) and ammonia concentrations of 5816 (standard deviation (SD): 3005.0) and 614 (SD: 268.7) mg/l, respectively. The mean MBR effluent for COD and ammonia was 37 and 86 mg/l, respectively. The mean treatment performance of the constructed wetland for COD, ammonia and suspended solids was 205, 67 and 57 mg/l, respectively.     

移动在线实时绘制技术研究综述

移动在线实时绘制技术受移动互联网发展的驱动,为3维可视化、计算机视觉、虚拟现实、增强现实、扩展现实和元宇宙等新兴研究领域提供了核心技术的支撑。本文以在线实时绘制技术为切入点,探讨了该技术在移动端、Web端、云端和多端协同这4类平台下的发展重心和研究现状,并深度阐述了工业级在线云平台的实施方案。首先,针对移动端的在线实时绘制,分析了近年来移动端绘制硬件构架设计的优化方向;探讨了在功耗和带宽受到制约的情况下移动端如何对渲染算法进行加速,如何对高功耗的光线跟踪算法进行优化;列举了包括图形应用程序编程接口(application programming interface,API)和游戏引擎在内的移动端渲染工具。然后,针对Web端在线实时绘制,分析了Web端的3D渲染机制,梳理了以3D场景的轻量化预处理、大规模3D场景的细粒度化网络传输、3D场景的对等传输以及Web3D在线特效渲染为代表的Web端在线绘制的关键技术(尤其面向大规模3D场景),列举了国内外知名Web3D引擎并探讨了主流游戏引擎对Web3D应用的支持。再后,针对云端在线实时绘制,从应用托管、资源调度和串流这三大云平台的核心功能入手,调研了以串流应用优化技术为核心的在线云绘制现状。此后,从多端绘制任务分摊机制入手,分析了以“端云”协同和“端边云”协同为目标的在线多端协同绘制的发展。最后,以当前工业级在线云绘制平台为研究对象,分析了包括微软、英伟达、Unity、酷家乐等一线云绘制企业的在线实时云绘制平台方案,验证了移动在线绘制技术在工业界的实用性。     

基于参数化特征造型的建筑造型设计研究

介绍了一种建筑渲染图快速建模方法．采用参数化特征造型和尺寸驱动技术后，建筑建模由２维快速草图设计和尺寸标注完成，用于渲染着色的建筑３维模型可以按照２维模型由系统自动生成．通过建筑特征样式定义和缺省设计，实现特征参数的约束与继承，避免了设计中的重复和错误，提高了设计速度．该算法是通过ＡＵＴＯＣＡＤ的Ｃ语言开发工具ＡＤＳ实现的．     

基于数字高程模型的输电线路虚拟地形绘制优化算法

针对现有输电线路仿真培训系统复杂地形和大规模场景的建模问题,研究了基于数字高程模型(DEM)的虚拟地形绘制优化算法.通过采集输电线路走廊位置和范围内的地形高程数据,结合分治算法和流水线技术实现Delaunay三角网的并行构建.并针对高斯曲面方程拟合三角形表面中的参数问题,提出了基于遗传算法的最优参数选择方法,降低了地形表面的整体误差.在Qt平台上实现了输电线路真实场景的三维可视化重构.仿真结果表明,本算法有效实现了输电线路真实地形的虚拟可视化,提高了虚拟场景的还原度和沉浸感.