Experimental investigation of particle contact time at the wall of gas fluidized beds

The contact time of particles at the walls of gas fluidized beds has been studied using a radioactive particle tracking technique to monitor the position of a radioactive tracer. The solids used were sand or FCC particles fluidized by air at room temperature and atmospheric pressure at various superficial velocities, covering both bubbling and turbulent regimes of fluidization. Based on the analysis of tracer positions, the motion of individual particles near the walls of the fluidized bed was studied. The contact time, contact distance and contact frequency of the particles at the wall were evaluated from these experimental data. It was found that in a bed of sand particles, the mean wall contact time of the fluidized bed of sand particles decreases by increasing the gas velocity in the bubbling and increases in the turbulent fluidization. In other words, the particle-wall contact time is minimum at the onset of turbulent fluidization in the bed of sand particles. However, the mean wall contact time is almost constant in both regimes of fluidization in the bed of FCC particles. All the existing models in the literature predict a decreasing contact time when the gas velocity in the bed is increased. It was also shown that the contact distance increases monotonously by increasing the gas velocity in the bed of sand particles, while it is almost constant for the bed of FCC particles. Contact frequency has a trend similar to that of the contact time for both sand and FCC particles.     

独立学院创新“寝室联系员负责制”管理模式及其价值

根据自身发展的特点和学生的具体情况,独立学院创新学生管理模式,引入＂寝室联系员负责制＂管理机制,通过三个管理层,四大制度,充分调动学生工作积极性,发挥学生党员的先进性和学生骨干的模范带头作用,发挥其在思想建设、学风建设、学生管理等各方面的桥梁作用,推动学生党员、学生骨干和寝室成员共同进步,推动独立学院教学质量提高和人才培养,促进和谐校园建设。     

大口径光学透镜瞬态温度场模拟

为考察热辐射效应对光学元件稳、瞬态温度场的影响,给出了考虑辐射和导热耦合换热情况下复杂几何结构光学透镜稳、瞬态热特性的适体坐标下离散坐标法.对喷管形和圆柱形介质进行计算并与其他方法比较表明,建立的适体坐标系下辐射与导热耦合换热计算方法精度较好.对两端为球缺中间为圆柱的大口径透镜内的辐射与导热耦合换热过程进行了数值模拟.计算结果表明,为了精确地预测半透明介质如透镜内的温度分布,应该考虑辐射与导热耦合作用,且应当考虑介质的光谱特性.     

Compressibility of fine-grained soils subjected to closed-system freezing and thaw consolidation

In order to investigate the effects of freezing and thawing on the compressibility of fine-grained soils, freezing and thawing tests and subsequent compression tests with fine-grained soils in an oedometer were carried out. During the freezing, a part of the soils is loosened and another part is over-consolidated under the freezing pressure ?E. The compression curves after the freezing and thaw consolidation are neither different from the normal consolidation curve nor from the rebound curve of an unfrozen soil, until the consolidation pressure ?z = ?E is arrived. Based on the experimental results, a theoretical model has been developed to predict the frost heaves, the thaw-settlements and the compressive deformations of fine-grained soils after the thaw consolidation. The theoretical results are very close to the experimental results.     

周期阵列压痕奇异应力场与开裂（PartⅡ：压痕开裂临界载荷）

周期阵列压痕方法是研究微观摩擦学的工具之一。由于周期阵列刚性压头压在半平面弹性体的表面时,会产生周期的Ⅰ型奇异压应力场,该奇异应力场的应力集中达到一定程度时,即达到临界条件时,该奇异应力场所在的边界将开裂。压痕边界的开裂问题是一个新型的断裂力学问题,通过边界移动的能量释放率的分析给出了压痕边界开裂能量释放率数学表征,并给出边界开裂的临界载荷和临界开裂角。     

保偏光纤偏振主轴准直方法研究

本文利用信号分析的方法,对保偏光纤主轴位置进行计算和讨论,提出一种准直方法,该方法能适应不同种类保偏光纤的偏振主轴的准直。     

一种基于红外被动探测的车辆制动方法研究

为了进一步提高车辆防撞装置的可靠性、有效性,提出一种新的设计方法.该设计采用红外被动探测技术检测车辆前方障碍物,并将检测到的信号输入单片机,单片机通过判断接收红外辐射信号的变化,利用定时功能按时间顺序依次触发光报警、语音报警以及启动刹车.红外被动探测器的使用改变了现有车辆防撞装置的设计思路,省去了发射部分,简化了设计;依时间先后触发报警信号避免了测距,提高了信号处理的速度,一定程度上改善了车辆防撞装置的性能.仿真结果表明,该方法具有较好的实用性.     

基于定性与定量分析的联络中心任务量预测法

任务量预测是联络中心人员排班的第一步,如何精确预测联络中心的任务量并相应地安排适当数量的座席人员来处理客户的需求是联络中心管理人员面临的首要问题.提出采用定性分析与定量分析相结合的任务量预测方法.对于给定的任务量数据,首先,采用观察法进行定性的分析区分异常和正常数据,然后,分别选定合适的定量预测方法进行预测.任务量定量预测方法包括趋势拟合、线性回归、移动平均、时间序列分解等预测方法.通过定性分析与定量分析相结合的综合应用方法,给出更准确的联络中心任务量预测方案,帮助管理人员最大程度的减少放弃和被拥堵在队列中的任务数量,设计制定可行性高的座席人员数量及人员排班.     

基于ROC曲线的镜片舒适度眼动指标研究

基于眼动仪检测到的受试者眼动数据,提出一项新的眼动指标——眼睑间距变动百分比,并对比传统的眼跳次数、瞳孔直径等眼动指标,经过显著性和相关性分析后,最后利用受试者特征曲线（Receiver operating characteristic,ROC）曲线评价每个眼动指标对镜片舒适度的判别性能。实验结果表明,本文提出的眼睑间距变动百分比反映镜片舒适度的性能最好,瞳孔直径次之,眼跳次数和平均注视时长相仿。本实验结果证明可以通过检测患者的眼睑间距变动百分比,来准确快速地判断镜片的舒适程度。这项研究成果能帮助相关从业者从更加客观的角度评价镜片的舒适程度,也为中国当前日益严峻的近视防控形势提供了一定的技术理论帮助。     

基于LabVIEW的透镜多参数自动检测系统开发

质量检测是光学透镜生产的重要环节,目前大部分透镜生产企业还停留在半自动检测阶段,质检的效率和精度很大程度上取决于工人的熟练程度;且不同参数的检测需要人工搬运镜片到不同的质检工位上,质检过程中的反复搬运容易造成镜片表面污染和损伤;为此提出一种基于LabVIEW的透镜多参数自动检测系统的设计方法,在一个工位上同时完成多个质量参数的测量,并对透镜进行自动搬运和分选,检测结束后自动生成质检报表;最后使用某型号凸型圆形透镜对开发的检测系统进行了实验验证,实验结果表明,检测系统具有测量精度高、可扩展能力强、界面直观等优点。