Study on the Dynamics of Tribocharged Coal and Mineral Particles in Free-Fall Triboelectric Separator

The dynamics of 2.0?0.8 mm or 0.8?0.5 mm size fraction of tribocharged organic coal, pyrite, and calcite particles were studied under the electric field using the high-speed dynamic camera combined with high-speed motion analysis system. Motion images of these particles were obtained and used to analyze their dynamic parameters. Organic coal particles tribocharged positively move to the negative plate, while pyrite and calcite particles reach the positive plate under the influence of electric force. These results indicate that the trajectories of all 2.0?0.8 mm particles are similar to parabolic curves. For 0.8?0.5 mm particles, the trajectories are approximate straight line, except for the calcite. The vertical velocities of all particles increase with a fluctuant acceleration as a result of gravity and drag force. The horizontal velocities of all particles vary slightly. The dynamics of 0.8?0.5 mm particles prove that size is very important for the triboelectric separation. The actions of electric force and drag force are increased with the decrease of particle size.     

Analysing observer preferences when presenting a product in a rendered scene: 2D vs. autostereoscopic 3D displays

ABSTRACT

This research compares the way the image of a product included within a rendered scene shown on an autostereoscopic 3D display is rated versus the same image shown in a 2D display. The purpose is to understand the observer's preferences and to determine the features that a composition should have to highlight the product and to make its presentation more attractive to observers, thereby helping designers and advertisers who use both displays to prepare images to make them more effective when visually presenting a product.

The results show that observers like the images on autostereoscopic 3D displays slightly more than those presented by means of 2D displays. On both displays the product is perceived more quickly when it is larger than the other elements and is shown with greater chromatic contrast, but a composition is seen as more attractive when the chromatic relationship between all the elements is more harmonious.     

Passenger comfort on high-speed trains: effect of tunnel noise on the subjective assessment of pressure variations

When passing through a tunnel, aerodynamic effects on high-speed trains may impair passenger comfort. These variations in atmospheric pressure are accompanied by transient increases in sound pressure level. To date, it is unclear whether the latter influences the perceived discomfort associated with the variations in atmospheric pressure. In a pressure chamber of the DLR-Institute of Aerospace Medicine, 71 participants (M = 28.3 years ± 8.1 SD) rated randomised pressure changes during two conditions according to a crossover design. The pressure changes were presented together with tunnel noise such that the sound pressure level was transiently elevated by either +6 dB (low noise condition) or +12 dB (high noise condition) above background noise level (65 dB(A)). Data were combined with those of a recent study, in which identical pressure changes were presented without tunnel noise (Schwanitz et al., 2013, ‘Pressure Variations on a Train – Where is the Threshold to Railway Passenger Discomfort?’ Applied Ergonomics 44 (2): 200-209). Exposure-response relationships for the combined data set comprising all three noise conditions show that pressure discomfort increases with the magnitude and speed of the pressure changes but decreases with increasing tunnel noise.

Practitioner Summary: In a pressure chamber, we systematically examined how pressure discomfort, as it may be experienced by railway passengers, is affected by the presence of tunnel noise during pressure changes. It is shown that across three conditions (no noise, low noise (+6 dB), high noise (+12 dB)) pressure discomfort decreases with increasing tunnel noise.     

Fit‐first to be tied

This poem summarizes the fit‐first method of camera evaluation described in Jim Worthey's “Applications of vectorial color.” The algorithm works with the locus of unit monochromats (LUM) in camera and CIE color‐matching spaces. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011;     

我国高铁建设融资模式再探索

作为公共基础设施建设的重要组成部分,高铁建设具有自然垄断性、地方公共产品性、成本积聚性以及收益长期性等经济属性。高铁建设一般采取政府投资为主、BOT项目融资为辅的融资模式,而政府投资和BOT项目融资模式都存在一定的限制,为满足高铁建设的巨大资金需求,需要探索和尝试更可行、合理的融资模式,制定支持性政策和配套制度。     

黏质黄土地层高铁隧道变形控制基准研究

黄土隧道具有埋深浅、开挖时变形量大、稳定性差的问题,下穿既有建构筑物时,给地表建构筑物的安全带来巨大的影响,需保证开挖过程中变形在规范规定的范围内。针对黏质黄土地层高铁隧道开挖过程中的拱顶及地表变形规律进行分析,结合现场实测数据的分析,得出黏质黄土地层中隧道的沉降量与埋深及开挖方法有直接关系,相同的埋深下地表沉降与拱顶沉降有着显著的线性关系,其比值与施工方法的相关性不大。进一步得出了基于地表沉降控制要求的黏质黄土地层高铁隧道施工变形控制基准:S_v=[δ]/i_H,可供类似工程进行变形控制提供依据。     

浅谈高速桥梁施工中智能张拉的应用

智能张拉系统的优势显著,表现为可靠的控制和便利的操作,被广泛应用于预应力桥梁当中,文章概述了智能张拉的原理。基于此,就其在高速桥梁施工中的现实应用做出了论述。并通过案例,对其应用做出了具体直观的分析与说明。     

W18Cr4V高速钢渗铬热处理对HFCVD金刚石膜生长的影响

采用热丝化学沉积法在高速钢基体上沉积金刚石薄膜.为了减少石墨的形成、增强膜基结合强度,沉积前先使用渗铬热处理在高速钢表面制备一层碳化铬中间层.采用场发射扫描电子显微镜、X射线衍射仪、激光拉曼光谱和洛氏硬度计对渗铬基体和金刚石膜进行检测分析,研究渗铬热处理对高速钢基体与金刚石膜的物相组织、结构形貌和附着性能的影响.结果表明:渗铬热处理能在钢基表面形成一层致密的富Cr层,此过渡层能有效提高金刚石的形核率,在渗铬钢基表面形成连续致密的高质量金刚石膜,但该金刚石膜的应力较大,1 471N载荷的压痕测试导致薄膜严重破坏,说明膜基结合强度有待进一步提高.     

不同过渡层对钢基金刚石薄膜的影响

采用超高真空热丝化学气相沉积(HFCVD)系统,以甲烷和氢气为反应气体,在高速钢W18Cr4V基体上利用3种不同的过渡层(WC、Cr、WC/Cr)制备金刚石薄膜。采用场发射扫描电子显微镜(FE–SEM)、X射线衍射仪(XRD)、显微激光拉曼光谱仪(Raman)以及洛氏硬度计对过渡层和金刚石薄膜进行检测分析,研究了不同过渡层对金刚石薄膜形貌质量和附着性能的影响。结果表明,3种过渡层均可以有效减少钢基中Fe对金刚石薄膜的负面影响,提高金刚石的形核率;其中,采用WC/Cr过渡层时膜基间残余应力最小,仅为0.25 Gpa,附着性能最好。