沐若水电站大坝碾压混凝土石粉掺和料应用研究

沐若水电站大坝为全断面碾压混凝土重力坝,因当地人工砂的细度模数小,石粉含量高,为降低工程造价,合理利用资源,减少对环境的污染,对石粉作为掺和料进行了一系列现场试验研究。结果表明,只要采用合适的加工工艺控制人工砂的石粉含量在27%以下,以内含的方式按砂质量3%~4%的石粉作为掺和料配制碾压混凝土,就完全可以满足设计对碾压混凝土各项性能指标的要求。此项成果已成功应用于工程实际,取得了较好的效果。     

高有机物污染原水深度处理工艺选择和运行优化

P市地表原水受到有机物污染,水中CODMn经常高达10mg/L以上,为此,在G水厂的扩建工程中,采用了两级臭氧—生物活性炭深度处理工艺,以保证出水水质安全。水厂运行结果表明,在活性炭吸附饱和后,一级炭池出水CODMn仍有3～5mg/L,需二级臭氧—生物活性炭处理才能使出厂水CODMn小于3mg/L。当前后臭氧分级投加比例为3∶2时,有机物的去除率最高。     

Effect of automatic image realignment on visuomotor coordination in simulated laparoscopic surgery

During laparoscopic surgery, the surgeon's hand-eye coordination is often disrupted by the incongruent mapping between the orientation of the endoscopic view and the actual operative field. Two experiments were conducted to examine the effect of automatic image realignment on the performance of laparoscopic surgery. The first experiment investigated how visual-motor misalignment impacted laparoscopic surgery performance. Novice subjects were randomly assigned to one of the two paired viewing conditions in a simulated laparoscopic surgery environment: 1) the endoscope was either at the center of the modeled workspace with an optical axis of 90°, or at -45° from the midline of the subjects with an optical axis 45°; 2) the endoscope was either at 0°, or at 180° from the midline of the subjects, both with an optical axis of 45°. Each group of twelve subjects performed a dynamic point-and-touch task under the assigned pair of viewing conditions, each with eight image orientations, in a repeated-measures mixed design. The second experiment examined whether the automatic realigning mechanism that was activated mid-task (such that a congruent mapping between display and control was re-established if the mapping at the beginning of the task had been misaligned) was helpful to improve performance. Twelve novice subjects performed the same task as in the first experiment in a repeated-measures design. Performance was examined under three misaligned visuomotor mappings, each followed by the realigned mapping activated by the automatic realigning mechanism. Results showed that performance was best when the endoscopic image was perfectly aligned with the actual task space (0° image orientation), but degraded progressively as a function of deviation from perfect alignment. Subjects' performance maintained a consistent pattern across 8 image orientations regardless of optical axis orientation and endoscope location. Performance was improved with the automatic realigning mechanism. It is recommended that any solution to restore the visuomotor congruency in laparoscopic surgery should first align the image with the task space. This work has implications for the design of visualization systems in laparoscopic surgery.     

Research on 3D medial axis transform via the saddle point programming method

The present paper investigates the 3D medial axis transform of objects bounded by freeform surfaces via the saddle point programming method, a mathematical programming approach used to identify the saddle points of a function. After exploring the local geometry and saddle point property of 3D medial axis transform, the mathematical programming method is employed to construct the saddle point programming models. Based on the optimality conditions that the optimal solutions should satisfy, a generic algorithm for computing various medial axis points is developed. In order to identify the junction points and localize the problem, the boundary and the skeletal curves are divided into skeletal segments, and it is proved to be efficient and accurate by numerical examples.     

锈蚀钢筋混凝土梁的力学性能研究

对24根直径不同的钢筋和8根钢筋混凝土梁进行电化学加速腐蚀模拟后,研究了24根受损钢筋的伸长率、屈服强度和极限强度的变化规律,以及8根不同腐蚀程度钢筋混凝土梁的应力-应变、荷载-挠度曲线和强度的变化规律.结果表明:伸长率的降低是导致锈蚀梁失去安全性能的主要因素;梁的极限承载能力和延性首先呈上升趋势,然后成反比例下降,最后出现陡降,形成不统一的单体,最终发生脆性破坏.     

动态3D虚拟场景并行化光线跟踪加速结构设计

为提高光线与虚拟场景几何面片求交的计算效率,提出一种基于混合模式的空间加速结构。该方法改进传统的层次包围盒,把细分层次包围盒与空间均匀网格划分相结合,实现了可并行的混合空间加速设计。此外,把帧间可重用的数据抽取至数据缓存,建立多几何群组的加速结构共享,实现了光线跟踪算法的并行优化。实验证明,该混合加速结构能有效加快光线跟踪的光线场景求交判断速度,快速实现光线跟踪并行化计算。     

Study of Thermal Radiation Properties of Pyrolytic Carbon Protective Coatings for Monocrystalline Silicon Furnace

The thermal radiation properties of pyrolytic carbon （PyC） protective coatings for monocrystalline silicon furnace prepared by different processes were tested. The changes of normal emissivity of carbon materials caused by PyC protective coatings were discussed, and the influence of phase structure and surface appearance on the thermal radiation properties was investigated. The results show that the thermal radiation properties of PyC protective coatings with the wave band of 5 -25 I~m are better than C/C substrate, further, normal spectral emissivity of CVD PyC coating remains basically at 0. 85 - 0. 90, and the normal total emissivity can reach 0. 89, which shows high thermal radiation performance. For resin PyC coating and CVD PyC coating, the degree of graphitization are 44. 53% and 16. 28% respectively, and the R value of Raman spectrum are 0. g64 and 1. 384 respectively. Relatively disorder graphite structure of the latter causes various vibration modes, and the spectral emissivity is better, so the thermal radiation property of CVD PyC coating is excellent. A lot of spherical particles exists on the surface of the CVD PyC coating, and the more interface and spacing of particles reduce the number of particles per unit volume. Therefore, the scattering of thermal radiation is strongly strengthened, and the spectral emissivity is higher.     

基于流量预估的直拉式冷轧机液压张力控制策略

根据带钢性能和工艺开发的要求,开发了机架前后配置张力液压缸的直拉式冷轧实验机.通过设置张力控制器直接对实际张力进行闭环控制的方式,无法实现张力液压缸速度与轧制速度的匹配,也无法满足动态下高精度且稳定的张力控制要求.针对此问题,通过对张力液压缸流量方程的研究,提出了基于流量预估的液压张力控制策略.流量预估控制精确计算出同时满足张力液压缸移动速度和设定张力的伺服阀控制电流,同时对控制因子进行在线修正以获得最优预估控制效果.动态张力补偿控制补偿预估控制后剩余的张力偏差.现场应用效果表明,该策略取得了良好的控制效果,动态下张力控制误差小于±3%.     

上海地区冬季住宅室内外颗粒物浓度的相关性

对上海市某住宅建筑室内外PM10、PM2.5、PM1的浓度进行了测量,研究了最小通风量（外门窗关闭）条件下3种天气时颗粒浓度随时间变化的规律以及相关性,分析了颗粒物浓度与环境温湿度参数之间的关系.研究结果显示,测试期间,室内外空气中细颗粒（PM 2.5）占可吸入颗粒（PM 10）浓度比例分别达65％和87％以上;无明显室内源时,I/O比值小于1且随粒径减小而减小;室内外颗粒浓度相关性与粒径大小有关系,PM1、PM2.5的浓度相关性大于PM10.研究还表明,颗粒物浓度的关联性与天气状况有关系,多云、雨天和阴天时浓度关联性有显著差别;颗粒物的浓度受到室内外温湿度的影响,且受天气状况影响而呈现复杂性.