One-Dimensional Numerical Model for Nonuniform Sediment Transport under Unsteady Flows in Channel Networks

In this study, the proposed one-dimensional model simulates the nonequilibrium transport of nonuniform total load under unsteady flow conditions in dendritic channel networks with hydraulic structures. The equations of sediment transport, bed changes, and bed-material sorting are solved in a coupling procedure with a direct solution technique, while still decoupled from the flow model. This coupled model for sediment calculation is more stable and less likely to produce negative values for bed-material gradation than the traditional fully decoupled model. The sediment transport capacity is calculated by one of four formulas, which have taken into consideration the hiding and exposure mechanism of nonuniform sediment transport. The fluvial erosion at bank toes and the mass failure of banks are simulated to complement the modeling of bed morphological changes in channels. The tests in several cases show that the present model is capable of predicting sediment transport, bed changes, and bed-material sorting in various situations, with reasonable accuracy and reliability.     

新型四辊冷轧机工作辊双向移动技术

新型四辊冷轧机工作辊双向移动技术极大地提高了板形控制能力，降低了板带轧制过程中产生的边降，延长了轧辊使用周期，可广泛应用于板带轧制。     

变系数移距变位方法及其在非圆齿轮传动中的应用

针对齿轮传动提出变位系数随节曲线位置变化的设计方法,并应用于解决非圆齿轮传动的设计。首先建立具有移距变位量的生成齿条模型和节曲线纯滚动模型,而后用啮合方程将这两个模型结合起来,经坐标变换后在齿轮坐标系中获得变位非圆齿轮的齿廓曲线数学模型。根据非圆齿轮节曲线的曲率半径随节曲线位置变化的特点,提出一种由节曲线位置确定变位系数的变系数移距变位方法。以高阶椭圆齿轮的变位传动设计为例,设计了按余弦规律变化的变位系数函数,用计算机图形仿真的方法获得其齿廓曲线,验证了该方法的正确性。     

基于RBF的改进单神经元PID控制

提出一种基于RBF辨识神经网络算法的改进神经网络PID控制,应用最优控制理论中的二次型性能指标加入到控制算法中的加权系数学习修正部分,将RBF与单神经元相结合构成PID控制器,通过Matlab对指定对象仿真控制,得到了良好的效果.比起以往的神经网络PID控制,改进的算法在学习速度和实时性都得到了提高.     

核级阀门流体阻断试验技术研究

在试验装置上开展了压水堆运行参数范围内动力驱动阀门的流体阻断试验研究和止回阀的动态逆流与静态逆流试验研究。试验结果表明：开展动力驱动阀门流体阻断试验时，在设施能力不足的情况下可将阀门开启度适当减小，也能验证阀门阻断流体的能力；止回阀静态逆流试验相较于动态逆流试验能更苛刻地考验止回阀的阻断性能。本文结果可为开展同类验证试验在试验方法的选取上提供依据。     

基于多自由度结构的DTMD参数分析及设计方法

双调谐质量阻尼器参数较多,其设计方法、有效性的研究仍不完善,鉴于此,针对地面运动作用下多自由度结构双调谐质量阻尼器的优化设计方法进行了初步研究,推导了双调谐质量阻尼器的位移动力放大系数(DDMF)。基于最优化目标函数研究了优化设计参数对振型参与系数的敏感性;在此基础上,给出了一种双调谐质量阻尼器的优化设计方法,并通过某高层钢结构的仿真分析对该优化设计方法的有效性进行了评价,结果表明,优化设计后的双调谐质量阻尼器可有效降低受控结构的位移动力响应。     

煤与瓦斯突出矿井“采面零时差接替”管理的实践

煤与瓦斯突出矿井准备面,经过改进掘进施工工艺、提升巷道支护质量、优化采面准备方案,实现"采面零时差接替"。提高掘进施工队伍管理水平,推动矿井采掘安全质量标准化的常态化发展,提高企业效益。     

Local sparsity preserving projection and its application to biometric recognition

Multimedia Tools and Applications - Dimensionality reduction techniques based on sparse representation have drawn great attentions recently and they are successfully applied to biometric...     

Deformation-induced crystal–crystal transition of polybutene-1: an in situ FTIR imaging study

Crystal–crystal transition of polybutene-1 from forms II to I inside and outside a large hedrite or spherulite during deformation is investigated with in situ Fourier transform infrared sepectroscopic imaging technique and miniature tensile tester. Three stages have been observed for both of samples. In the first stage (strain ε < 0.2), form I crystal formed slowly under the effect of deformation. When entering the second stage II (0.2 < ε < 1.2), the crystal–crystal transition was accelerated significantly. In the third stage, form II translates into form I almost completely. It was also found that the transition rate inside large hedrite and spherulite is slightly faster than the surrounding initially, especially for the hedrite. However, the difference inside and outside becomes negligible when ε > 0.8. We proposed that the difference in crystal–crystal transformation between spherulite and hedrite is attributed to the different alignment of lamellar stacks in two samples. The results demonstrate the effect of different morphologies on the crystal–crystal transition during deformation.     

钛铁矿浮选药剂研究现状及展望

浮选工艺中药剂的合理使用可有效选别日渐贫、细、杂的钛铁矿.文章综述了阳离子型、阴离子型和组合型三类捕收剂,有机型和无机型两类抑制剂,金属离子和高锰酸钾等活化剂.文章指出相比传统捕收剂,组合捕收剂由于药剂之间的协同效应,在一定程度上提高了钛铁矿分选指标,但仍未妥善解决问题,需继续加强新型药剂研发和突破,其中阴、阳离子捕收剂配合使用具有不错发展前景;抑制剂通过减少脉石矿物表面活性位点,阻止了捕收剂对脉石矿物的吸附,有机抑制剂和组合抑制剂表现出优良的选别特性,是未来重点研究方向;活化剂通过提高矿石表面活性位点数量及活性,增强了捕收剂对目的矿物的吸附性,但存在污染问题,应加大绿色环保型活化剂的研发力度,以期活化剂早日投入生产,提高工业生产效率.