双相机多点触控系统

为解决多点触控系统花费高、分辨率不足、体积庞大、容易受环境光影响等问题,提出了一种采用双摄像机的多点系统,通过多手指的点击和移动动作实现人机交互。该系统以双摄像机监控交互平面上的手指输入,利用图像处理技术得到触点在双相机中的位置,再结合标定数据进行差值计算得到触点的屏幕坐标,通过对触点的跟踪得到多点数据。图片浏览互动平台的实验结果表明,本文所提出的系统可用于多点触摸,并且具有很好的精确度。     

沉水植物对水体净化的研究进展

 本文综述了沉水植物对富营养化水体及其他受污水体中的N、P、重金属和有机物的去除,及抑制藻类生长化感等作用的研究的进展,并分析沉水植物对其的去除率,沉水植物在水域生态修复中较高的应用价值,同时指出沉水植物净化水质中存在的问题,展望了沉水植物净化水质的前景及方向。     

境界顶柱安全评价未确知测度模型及其应用

 运用未确知测度理论,建立露天转地下境界顶柱安全性评价模型。从露天转地下矿山的地质条件和工程状况出发,选取境界顶柱厚度、抗压强度、抗拉强度、露天坑深度、节理分布、地下矿采矿方法和露天坑积水7项指标作为判别指标。根据实际情况建立未确知测度函数,采用信息熵理论获得各判别指标的权重,并依照置信度识别准则进行等级判定,最后得出境界顶柱的安全评价结果。采用该评价模型对新桥硫铁矿、石人沟铁矿和获各琦铜矿3座典型的露天转地下矿山境界顶柱的安全性进行评价,评价结果与已经完成露天转地下矿山的境界顶柱实际情况符合较好,因此,根据评价模型的评价结果,推断新桥硫铁矿采用的境界顶柱方案是可行的。研究结果表明,此安全评价模型可行,为境界顶柱安全性评价提供了一种有效的方法。     

Mechanical properties of Mn-doped ZnO nanowires studied by first-principles calculations

First-principles calculations were performed to investigate the mechanical properties of ZnO nanowires and to study the doping and size effects. A series of strains were applied to ZnO nanowires in the axial direction and the elastic moduli of ZnO nanowires were obtained from the energy versus strain curves. Pure and Mn-doped ZnO nanowires with three different diameters (1.14, 1.43, and 1.74 nm) were studied. It is found that the elastic moduli of the ZnO nanowires are 146.5, 146.6, and 143.9 GPa, respectively, which are slightly larger than that of the bulk (140.1 GPa), and they increase as the diameter decreases. The elastic moduli of the Mn-doped ZnO nanowires are 137.6, 141.8, and 141.0 GPa, which are slightly lower than those of the undoped ones by 6.1%, 3.3%, and 2.0%, respectively. The mechanisms of doping and size effect were discussed in terms of chemical bonding and geometry considerations.     

Design and calculation of low infrared transmittance and low emissivity coatings for heat radiative applications

The infrared transmittance and emissivity of heat-insulating coatings pigmented with various structural particles were studied using Kubelka-Munk theory and Mie theory. The primary design purpose was to obtain the low transmittance and low emissivity coatings to reduce the heat transfer by thermal radiation for high-temperature applications. In the case of silica coating layers constituted with various structural titania particles (solid, hollow, and core-shell spherical), the dependence of transmittance and emissivity of the coating layer on the particle structure and the layer thickness was investigated and optimized. The results indicate that the coating pigmented with core-shell titania particles exhibits a lower infrared transmittance and a lower emissivity value than that with other structural particles and is suitable to radiative heat-insulating applications.     

Research of {0001} crystal orientation for magnesium alloys solidified in a fashion of cellular crystals

The magnesium alloy grew in a fashion of cellular crystals during the process of unidirectional solidification, and the {0001} crystal face orientation in the cast ingot of the magnesium alloy was studied. The theoretical model and methodology were set up, and a corresponding experiment was carried out to verify the theoretical analysis results. The experimental results indicate that the {0001} crystal face of magnesium crystals parallels to the width direction for the thin-plate cast ingot when the magnesium grows in a manner of cellular crystals. The separation angle between the {0001} crystal face of magnesium crystals and the vertical axis line of the cast ingot is about 62° for the circular column cast ingot, which distributes in cone-type. The theoretical analysis results are basically in agreement with the experimental ones of previous literatures and this paper.     

Physical model of fluid flow characteristics in RH-TOP vacuum refining process

To understand the characteristic of circulation flow rate in 250-t RH-TOP vacuum refining process, the l:4 water model test was established through the bubble behavior and gas holdup in the up-leg to investigate the effects of different processes and equipment parameters on the RH circulation flow rate. With the increases of lifting gas flow rate, lifting bubble travel, and the internal diameter of the up-leg, and the decrease of nozzle diameter, the work done by bubble floatage and the circulation flow rate increase. The expression of circulation flow rate was derived from the regression analysis of experiment data. Meanwhile, the influences of vacuum chamber pressure and nozzle blockage situation on the circulation flow rate were discussed in detail by the bubble behavior and gas holdup in the up-leg. It is necessary to maintain a certain vacuum chamber liquid level in the molten steel circulation flow. Compared with a nozzle with symmetrical blockage in the up-leg, when a nozzle with non-symmetrical blockage is applied, the lifting gas distribution is non-uniform, causing a great effect on the molten steel circulation flow and making the circulation flow drop largely.     

页岩气表观渗透率与多流动机理及有效应力演化关系

由于多尺度孔隙存在纳米尺度到宏观尺度的过渡,气体在页岩中流动的主导机制会在达西流和努森扩散等运移机理之间发生转换,该现象结合页岩基质内的气体吸附作用使得页岩气渗透率的测算变得更为复杂.因此,在实验室尺度确定有效应力及气体运移方式对渗透率的综合影响力对实际页岩气开采中的渗透率及产量评估准确性有着不可忽视的影响.采用脉冲衰减渗透率测算法,在不同围压条件下,对氦气和二氧化碳在富含有机质的页岩薄片中的气体渗透率进行测量.结果表明:努森扩散作用在低孔压时对页岩气渗透率有显著的正面影响,其强度与孔压成反比.在较大围压作用下的高孔压下的超临界二氧化碳可导致页岩基质最大吸附量降低,进而增加表观渗透率.表观渗透率随着有效应力的变化在不同孔压区间有着截然相反的趋势,有效应力系数此时出现非单一值,其主要是由于孔压变化带来的气体流动机理变化而引起的.     

定远营遗址稳定性和微观劣化的研究

在自然环境的反复作用下,土遗址表层持续劣化并产生宏观病害,致使土遗址本体的稳定性存在隐患,合理评价土遗址的安全性为文物界所关注.以西北地区阿拉善盟定远营城墙为研究对象,定性分析城墙各段病害,测定城墙土样的基本物理指标和力学性能,运用ABAQUS软件进行数值模拟,对比分析自然状态和降雨条件下的城墙稳定性,发现随含水率提高城墙存在失稳的危险.在宏观劣化现象分析基础上,运用X射线衍射仪和扫描电镜技术对城墙内外部夯土的成分和微观结构进行研究,探讨城墙劣化的机理.对土遗址稳定性和微观劣化的分析方法揭示了残存土遗址的真实状态,有助于土遗址的保护和修复,避免土遗址修复方案的盲目性.     

基于信息熵与空间洛伦兹曲线土地利用空间结构研究——以鄱阳湖区12县

通过对鄱阳湖区2005年和2015年2期遥感影像进行解译,获取研究区域内各土地类型用地面积.从信息熵、均衡度、优势度和空间洛伦兹曲线2种角度研究了鄱阳湖区内12个县(市)10年前后不同的土地利用空间布局.结果表明:2005年鄱阳湖区地区土地利用结构信息熵值普遍偏低,且结构性较强; 2015年平稳上升,但在内部空间尺度上,鄱阳湖区的各个县(市)信息熵差异呈缩小趋势,表现为高熵值区减少,中熵值区和低熵值区增加; 近10年鄱阳湖区耕地和水域分布一直保持高水平的均衡状态,未利用地成为分布最不均匀的土地利用类型,未利用地在总面积减少的趋势下,分布均匀程度降低,草地的不均衡程度大幅度降低,居民点及工矿用地不均匀程度上升,林地基本维持稳定; 近10年鄱阳湖区土地利用熵值增大,无序性增强,各地类面积差异减少,各地类洛伦兹曲线整体向绝对均匀线有靠拢趋势,这说明鄱阳湖区土地利用结构呈现出比较合理的变化特征.