A highly active composite electrocatalyst Ni–Fe–P–Nb2O5/NF for overall water splitting

This work demonstrates a facile Nb₂O₅-decorated electrocatalyst to prepare cost-effective Ni–Fe–P–Nb₂O₅/NF and compared HER & OER performance in alkaline media. The prepared electrocatalyst presented an outstanding electrocatalytic performance towards hydrogen evolution reaction, which required a quite low overpotential of 39.05 mV at the current density of ?10 mA cm^?2 in 1 M KOH electrolyte. Moreover, the Ni–Fe–P–Nb₂O₅/NF catalyst also has excellent oxygen evolution efficiency, which needs only 322 mV to reach the current density of 50 mA cm^?2. Furthermore, its electrocatalytic performance towards overall water splitting worked as both cathode and anode achieved a quite low potential of 1.56 V (10 mA cm^?2).     

液相中气泡上升行为与界面传质:实验研究与数值计算

在工业生产过程中，气泡在液相中的上升行为及气液界面的传质行为极为常见。本文针对不同条件下气泡上升过程的实验研究方法以及数值计算方法进行了总结。从实验与数值计算的角度，综述了单气泡上升过程的影响因素、多气泡上升过程聚并与破裂的现象和机理以及工业装置中气液两相流型和气泡特性，并对传质模型进行了归纳，主要关注了气侧-界面传质模型的研究现状。综述结果表明：当前对于单气泡上升行为的研究较为充分，而对于多气泡的行为机理的研究尚需深入。此外，受到研究手段的限制，进行气侧-界面传质模型研究具有一定挑战性。针对当前的相关研究进展和存在的问题，对今后气泡上升行为和传质行为的研究提出以下建议，即开展气泡聚并与破裂可控性研究，强化对气侧-界面传质过程的研究，包括泡内流体行为可视化研究和相关传质模型的建立。     

双层集热棚式太阳能热气流发电装置研究

为解决传统温室大棚在保温和降湿方面存在的问题,扩大太阳能热气流发电应用范围,本文提出一种基于温室大棚的双层集热棚式太阳能热气流发电装置。给出了夏冬两季不同运行模式,同时对双层集热棚采光性进行计算和分析,结果表明,主集热棚内平均单位面积的太阳净辐射量为599.76W/m2,次集热棚内平均单位面积的太阳净辐射量为539.784W/m2,双层集热棚平均透光率为69.2%,符合国标规定的温室大棚光照要求,满足大棚夏季降温、降湿,冬季保温、降湿的要求,本研究可以实现太阳能发电和改善温室大棚作物的生长环境,具有一定的推广应用价值。     

斜坡倾角对山体导流塔太阳能热气流电站系统性能的影响

提出了一种在中高纬地区利用阳面山体坡地建造的山体导流塔太阳能热气流电站,该太阳能热气流电站的集热棚搭建在一定坡度的山体上,兼做导流塔,在山体顶部建造一定高度的垂直导流塔,并利用理论推导的方法研究了影响电站系统效率的主要因素。结果表明:斜坡倾角对山体导流塔太阳能热气流电站系统效率有较大的影响,在中高纬地区当斜坡倾角比纬度小7°～10°时,集热棚单位面积斜面上截获的年辐射量比水平集热棚高25%。另外由于山体导流塔太阳能热气流电站的集热棚同时可兼作部分导流作用,因此该系统可适当减小垂直导流塔的高度,减少工程施工难度。     

大型直线振动筛的疲劳寿命分析

由于在简谐激振力作用下大型直线振动筛在振动筛分工作时其横梁、侧板等主体结构件均处于多轴应力状态,因此利用临界平面法对大型直线振动筛的多轴疲劳损伤模型进行了疲劳寿命数值分析,得到了大型直线振动筛的对数疲劳寿命云图并分析了振动筛结构的疲劳寿命分布。分析可知,大型直线振动筛整体的疲劳寿命可以满足工作需要,疲劳可靠性较高,但振动筛体的侧板、横梁的局部疲劳安全系数不高,在设计使用过程中应引起足够的重视,必要时对大型直线振动筛的结构件进行优化重设计。     

基于Web的零件族信息集成管理系统的研究与实现

通过分析系统集成的必要性及零件族信息集成管理系统与企业其它系统的交互情况,提出基于Web Service的系统集成方案,建立了面向集成的零件族数据模型;利用XML技术表达、存储异构系统中格式化与非格式化产品数据的方法,开发出了基于Web零件族信息集成管理系统,实现了零件族信息集成管理系统与CAx系统及企业其他管理系统的动态集成,以及各系统间全生命周期零件信息的共享与重用。     

Q460E-Z35钢焊接传热过程的数值模拟

对Q460E-Z35钢进行了温度场和应力场的三维数值模拟。模拟结果验证了当钢材与所选的焊材匹配时,不产生裂纹的最低预热温度为150℃,提高预热温度可以更好地提高焊接材料的抗裂性。模拟结果对Q460E-Z35钢焊缝抗裂纹的能力、焊接接头的使用性能以及焊接接头抗脆性断裂的优化设计具有指导意义。     

日照作用下钢管混凝土构件截面温度场的实验研究

在日照作用下对钢管混凝土构件进行截面温度场测试,分析了截面温度场随日照方位及截面空间分布的变化规律。结果表明,截面温度场随时间及截面空间变化的非线性均很显著;钢管表面各测点与圆心测点出现温度峰值的时间存在相位差;沿截面直径方向,各测点温度变化随直径缩小趋缓,即越靠近圆心,测点温度变化越滞后于环境的变化;圆心点的温度变化受各个方向温度变化的共同作用,但更多地受到强势方向的影响。     

A numerical database for ultrasonic defect characterisation using array data: Robustness and accuracy

Elastodynamic scattering matrices are known to contain geometrical information about a given scatterer, such as its size and shape. Here, the extent to which this scattered information can be retrieved using an ultrasonic array and used to characterise defects for Non-Destructive Evaluation is explored. Experimentally measured defect scattering matrices are compared to a database of possible scatterers and the nearest neighbour used to characterise the defect's geometry in terms of crack length and orientation. As an example, a database of scattering matrices for small (lengths 0.2–2.0 mm) cracks at a range of frequencies (2–20 MHz) is formed. The short range similarity (i.e. that between close neighbours) and the long range similarity (i.e. uniqueness) are used to understand the uncertainties inherent in this approach. In addition, the effect of spatially coherent noise, such as grain scattering in a polycrystalline metal, on the scattered information content is quantified. It is shown that as the noise level or frequency increases, so the information retrievable from a given crack is reduced, setting bounds on the accuracy of characterisation possible from a given ultrasonic dataset.     

Ammonia-water mixture property code (AWProC) development,verification and Kalina cycle design for nuclear power plant

The improvement of thermodynamic efficiency of power plants is of great interest for the whole energy industry. The use of Kalina cycle has a great potential to improve the thermal efficiency of a nuclear power plant. This cycle uses a mixture of ammonia and water as working fluid. In this paper, we discuss the development of an Ammonia-Water mixture Property Code (AWProC). The estimation of the mixture properties are based on the Gibbs free energy functions. The code is verified and validated against experimental data available in the literature and REFPROP code. It is shown that AWProC can accurately estimate the thermodynamic properties of ammonia-water mixtures over a wide range of conditions, including high temperature and pressure regions. The code is then used to investigate the feasibility of applying the Kalina cycle to a typical Pressurizer Water Reactor (PWR) plant as an effective way to improve the plant efficiency. The fundamental of Basic-Kalina (B-K) cycle is described in detail firstly. Then, two modified configurations, Recuperation-Kalina (R-K) and Flash-Kalina (F-K) cycles respectively, are proposed for a typical 1000 MWe PWR. The simulation results indicate that the R-K type cycle can reach about 31.2% efficiency with simple equipment requirements, while the F-K type cycle can reach efficiencies up to about 34.8%, but at the expenses of a slightly more complex design. The present work demonstrates the applicability of the Kalina cycle as a way to improve the thermal efficiency of a nuclear power plant. This concept is meaningful for improving nuclear power plants economic and competitiveness.