Algorithms of wavefront generation for aspheric surface measurement

For aspheric surface measurement with wavefront sensing technology, after obtaining the slope or curvature as the measurement raw data, the data processing algorithm must be re-studied for high performance in practical application. This paper designs, analyzes and compares five different algorithms to generate wavefront for aspheric surface measurements, especially for practical measurements with noises and missing data. Simulation and experimental results show that in ideal condition without any noise in the system, direct fitting yields perfect results without error; the algorithms including Southwell reconstruction achieve better results under practical conditions, where there exist real issues such as noise and abnormal data. Reconstruction is therefore an essential step as it significantly improves the measurement stability and reliability, and enables the system feasible for practical applications. Furthermore, Southwell algorithm is extended for applications with missing data, which is most likely happen when the surfaces to be measured possess large dynamic range.     

Hot electrons induced degradation in lattice-matched InAlN/GaN high electron mobility transistors

In this paper, lattice-matched Pt/Au-In_0.17Al_0.83N/GaN high electron mobility transistors (HEMTs) were fabricated, and the degradation characteristics of the gate leakage current were investigated by drain-to-source voltage (V_DS) step-stress measurements under the ON, semi-ON, and OFF stress conditions and at different temperatures, respectively. It is found that, (1) there exists a critical value of V_DS, beyond which the gate leakage current begins to increase significantly; and (2) the degradation of gate leakage current has a positive temperature coefficient, indicating that high temperature can accelerate the degradation. A hot electron model is used to explain the experimental results, emphasizing that the hot electrons from the channel can induce additional negatively charged defects at the InAlN/GaN interface, which can increase the local electrical field and introduce a thinner surface barrier and finally enhance the vertical leakage current component, leading to the current degradation.     

Numerical investigation of liquid cooling cold plate for power control unit in fuel cell vehicle

This paper proposed fifteen structure schemes of the liquid-cooled plate for thermal control of the power control unit (PCU) in fuel cell vehicle (FCV). At the given serpentine channel with inconstant width, pin fin arrays with various configurations were arranged to improve the performance of three heating zones with multiple heat sources. Based on the same setup and boundary conditions, numerical simulations were conducted for different schemes. The solutions were validated by grid independence check and comparison with previous researches. Effects of fin geometrical parameters (such as diameter, height, fin pitch and shape) on pressure drop and heat transfer characteristics were investigated. Furthermore, two dimensionless factors η_H and η_P were quantified to evaluate the heat transfer enhancement and pressure drop augmentation. The dimensionless performance evaluation factor P_EF was cited to assess overall performance of the cold plate. Based on three factors mentioned above, cooling performances of three heating zones and the whole plate were compared among all schemes. According to the performance comparison, scheme 12 employing circular fins with diameter of 4 mm was selected as the optimal solution for the cold plate.     

电法勘探在新乡市新近系泥灰岩地区找水中的应用

新乡市凤泉区是2011年河南省受旱最为严重的地区之一,该区主要的含水层为新近系泥灰岩。针对该区含水层的地球物理特性,采用高密度电阻率法和激发极化对称四极测深进行地下水勘查找水,取得了良好的效果。这两种地下水勘查的物探技术方法组合在同类地区有着较好的借鉴作用。     

轻型井点降水工艺在人工填土地层内适用性研究

结合某工程实例,介绍了轻型井点降水工艺在天津地区的应用情况,通过对工程地质及水文条件的分析,研究了轻型井点降水工艺在人工填土地层内的适用性,为该工艺的进一步推广应用奠定了基础。     

子牙河—海河流域浅层地下水矿化度分布及成因

对天津地区子牙河—海河干流流域浅层地下水矿化度及水化学类型分布进行了调查,发现地下水矿化度由低到高、从微咸水到咸水再到盐卤水渐变特征明显,对其形成原因进行了分析,认为地下水补给不足以及深层地下水开采形成降落漏斗和渤海湾风暴潮等引起的海水入侵是导致该分布特征的主要原因。     

不同类型地埋管钻孔换热能力对比分析

为完成浅层地热能调查项目,进一步推广其开发利用,天津市建立了土壤源地源热泵试验基地,开凿了80m、120m垂直钻孔以及120m的斜钻孔,回填不同类型的材料,并使用地层热物性测试仪进行现场热响应试验。本文通过对比分析各地埋管钻孔的换热能力,得出深度120m、垂直、双U型以原浆加中粗砂作为回填材料的地埋管钻孔换热效率最高,并对地埋管斜钻孔的合理利用提出建议,为以后的土壤源热泵工程设计提供经验。     

高效澄清池在煤化工企业回用水处理中的应用

神华包头煤制烯烃回用水工程利用Siemens的Contrafast高效澄清池对煤化工的回用水做预处理,出水水质达到了设计标准,33 600 m3/d出水全部用作循环水补充水.与传统的混凝沉淀池相比,高效澄清池具有出水水质好、耐冲击负荷、排放的污泥浓度高且沉淀效率高等优势.其组成包括完成混合反应过程的混合槽和反应池,以及完成水与絮凝体分离的沉降池等.     

聚醚改性有机硅消泡剂对日化废水处理工艺的影响研究

选用天津某日化厂典型废水添加不同浓度的9262-1型聚醚改性有机硅消泡剂制成混合水样,考察消泡剂在混凝沉淀、水解酸化及好氧活性污泥工艺的连续运行过程中对废水处理效率的影响。结果表明,在消泡剂添加浓度小于0．4mg／L的情况下,对各级反应基本无影响;而浓度高于0．6mg／L的情况下,会对各级反应产生不利影响。     

UASB-生物接触氧化工艺处理高果糖浆生产废水

采用UASB-生物接触氧化工艺处理高浓度的高果糖浆生产废水。运行结果表明,UASB和生物接触氧化池的COD去除率分别为85%～92%和60%～71%,出水水质大大优于污水综合排放标准(GB 8976-1996)的三级排放标准。