供水管网中压力真实值的批次平差算法

分析了测压点优化布置的意义及原则,并根据供水周期性,依靠数量有限的测压点压力数据,结合管网的水力计算,利用传统的平差原理,将测压点以外的其它节点压力进行真实性校正,推算出了管网各节点的真实压力值,实现了通过有限测压点数据对管网所有节点压力的全面了解。     

广东韩江松源河省界界面水质变化及环境管理策略

根据2007、2008年7次调查的实测资料,分析了松源河及多宝水库的水质变化过程,并讨论了影响水质恶化的原因;根据水质变化特点,提出了水质保洁及科学管理的策略,为梅州的绿色崛起、“以人为本”的和谐社会服务.     

Limit load and shakedown analysis of plastic structures under stochastic uncertainty

Problems from plastic analysis are based on the convex, linear or linearised yield/strength condition and the linear equilibrium equation for the stress (state) vector. In practice one has to take into account stochastic variations of several model parameters. Hence, in order to get robust maximum load factors, the structural analysis problem with random parameters must be replaced by an appropriate deterministic substitute problem. A direct approach is proposed based on the primary costs for missing carrying capacity and the recourse costs (e.g. costs for repair, compensation for weakness within the structure, damage, failure, etc.). Based on the mechanical survival conditions of plasticity theory, a quadratic error/loss criterion is developed. The minimum recourse costs can be determined then by solving an optimisation problem having a quadratic objective function and linear constraints. For each vector a(·) of model parameters and each design vector x, one obtains then an explicit representation of the “best” internal load distribution F^∗. Moreover, also the expected recourse costs can be determined explicitly. Consequently, an explicit stochastic nonlinear program results for finding a robust maximal load factor μ^∗. The analytical properties and possible solution procedures are discussed.     

汽包水位粒子群-PID优化控制

对循环流化床锅炉汽包水位控制系统,采用串级三冲量PID控制,应用粒子群优化算法对PID控制器进行参数整定,并获得了最优参数。仿真结果表明,与传统整定方法相比,这种参数整定方案使汽包水位控制系统具有更好的控制品质,提高了系统的静动态特性。     

水处理系统的分段优化设计方法

采用分段设计法研究水处理过程.根据给水浓度和产水浓度要求的不同,以年费用最小为目标,将水处理过程作为超结构模型,进而优化设计段数和每段的工艺参数.研究表明,当进水浓度为5 000 ppm～35 000 ppm时,制备生活用水采用反渗透法处理费用最低,而制备纯水采用反渗透+离子交换联合法处理费用最低;当进水浓度为500 ppm～5 000 ppm时,前者采用电渗析法处理费用最低,而后者采用电渗析+离子交换联合法处理费用最低;当进水浓度小于500 ppm时,制备纯水采用离子交换法费用最低.     

拓扑距离特征指数对多氯联苯的QSPR研究

根据分子拓扑理论,提出1种新的多氯联苯(PCBs)化合物分子中,顶点原子(基团)点价值δ_i的计算方法,据以构建分子的结构参数——拓扑距离特征指数(TDEI);同时考虑分子体积以及氯原子在苯环上的位置和数目对PCBs性质的影响,引入分子体积参数(V_R)和基团定位指数(D),然后,采用多元线性回归法,分别建立了PCBs的正辛醇-水分配系数(lgK_(OW))和水溶解度(-lgS_w)的定量结构-性质相关模型,其相关系数分别达到0.9972和0.9730,均优于前人的工作。利用模型预测另外7个PCBs分子的lgK_(OW)和-lgS_W,预测值与实验值的一致性令人满意。     

超高速水下航行器横滚控制研究

超高速水下航行器航行时由于被超空泡包裹着,使得其工况变得更为复杂,控制难度进一步加大;为了抑制或消除横滚,文章通过分析超高速水下航行器的运动特点,建立了航行器横滚运动模型方程,并进行特性分析和控制规律综合设计,最后提出使用配置控制面的方法来实现它的横滚控制;此方法的使用既为系统提供控制力又解决了系统弱阻尼的问题,同时还提高了系统的响应速度;最后运用PD算法,分析它的动态特性和幅频特性,仿真结果表明此方案简单,容易实现,且鲁棒性好,满足系统的要求。     

基于TwinCat的控制器在液位控制中的应用

介绍一种基于TwinCat控制平台的水箱智能控制系统,用以提高化工生产中水罐液位的控制速度.该系统主要利用TwinCat控制平台,完成下位机与上位机的数据通信;采用自学习模糊控制和PI控制相结合的智能控制算法.用VC++语言完成控制算法程序,采集下位机的监控数据,改变模糊控制规则,实现对水箱的液位控制.另外,通过编程完成了上位机监控界面的设计.实验结果表明,与模糊控制或PI控制相比,该设计控制效果较好,证明了算法的有效性.     

Metal Single-Site Molecular Complex–MXene Heteroelectrocatalysts Interspersed Graphene Nanonetwork for Efficient Dual-Task of Water Splitting and Metal–Air Batteries

Development of multifunctional electrocatalysts with high efficiency and stability is of great interest in recent energy conversion technologies. Herein, a novel heteroelectrocatalyst of molecular iron complex (Fe_MC)-carbide MXene (Mo₂TiC₂T_x) uniformly embedded in a 3D graphene-based hierarchical network (GrH) is rationally designed. The coexistence of Fe_MC and MXene with their unique interactions triggers optimum electronic properties, rich multiple active sites, and favorite free adsorption energy for excellent trifunctional catalytic activities. Meanwhile, the highly porous GrH effectively promotes a multichannel architecture for charge transfer and gas/ion diffusion to improve stability. Therefore, the Fe_MC–MXene/GrH results in superb performances towards oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The practical tests indicate that Zn/Al–air batteries derived from Fe_MC–MXene/GrH cathodic electrodes produce high power densities of 165.6 and 172.7 mW cm⁻², respectively. Impressively, the liquid-state Zn–air battery delivers excellent cycling stability of over 1100 h. In addition, the alkaline water electrolyzer induces a low cell voltage of 1.55 V at 10 mA cm⁻² and 1.86 V at 0.4 A cm⁻² in 30 wt.% KOH at 80 °C, surpassing recent reports. The achievements suggest an exciting multifunctional electrocatalyst for electrochemical energy applications.     

Abrasion-Resistant and Enhanced Super-Slippery Flush Toilets Fabricated by a Selective Laser Sintering 3D Printing Technology

Flush toilets waste a significant amount of water every day due to the unavoidable adhesions between human waste and the toilet surfaces. Super-slippery surfaces can repel complex fluids and various viscoelastic solids, however, are easily broken by mechanical abrasions. Herein, the fabrication of an abrasion-resistant super-slippery flush toilet (ARSFT) is reported using a selective laser sintering 3D printing technology. Unlike traditional super-slippery surfaces with limited thicknesses which can be easily worn away, the powder-sintered strategy endows the ARSFT not only with a self-supporting 3D complex shape but also with a porous structure that can accommodate considerable lubricants for an abrasion-resistant super-slippery property. As a result, the as-prepared ARSFT remains clean after contacting with various liquids such as milk, yogurt, highly sticky honey, and starch gel mixed congee, demonstrating excellent repellence to complex fluids. Besides liquids, the ARSFT exhibits a high resistance to sticky synthetic feces. Notably, even after being abraded to 1,000 cycles of abrasion using sandpaper, the ARSFT maintains its record-breaking super-slippery capability. The concept of the 3D-printed object with a superior abrasion-resistant slippery ability will improve the development of super-slippery materials and further save water consumption in the human society.