变化环境下考虑物理机制的SD需水预测研究

随着气候变化与人类活动作用的加剧,流域水资源受变化环境的影响愈加显著。研究变化环境下的流域水资源系统变化特征及需水预测对支撑流域水资源管理与合理配置具有重要的指导意义。基于系统动力学原理,耦合了考虑物理机制的需水预测方法,建立水资源系统模型,以黄河流域为例,分析了多因子驱动及多要素胁迫作用下黄河流域水资源系统变化特征,采用MPI气候模式预估的未来气温、降水结果及未来流域5种不同的经济社会发展情形,预测了黄河流域2017—2030年的水资源供需演变趋势。结果表明:①黄河流域的生活需水量随着流域人口及人均用水需求的增加不断增长。随着产业结构调整,工业需水量呈现缓慢减少态势,生态及三产需水量逐年增加,农业灌溉需水量呈下降趋势;②在加强流域水资源管理力度、增加节水技术投资的前提下,保障流域经济、社会协调发展,注重发展经济的同时兼顾流域生态环境保护,满足黄河流域下一阶段的经济社会可持续发展的要求;③为保障黄河流域水资源可持续发展,实现黄河流域生态保护和高质量发展,需要调整流域水资源管理策略,提高节水程度,促进流域产业结构优化。     

硫酸盐含量对全固废材料固化盐渍土抗压强度的影响

为探讨硫酸盐含量对全固废材料固化盐渍土抗压强度及微观结构的影响,采用击实试验和无侧限抗压强度试验,并结合扫描电镜、EDS、X射线衍射和热重分析等微观测试结果,从固化盐渍土的火山灰反应产物及其数量等角度分析含盐量对固化盐渍土抗压强度变化的影响。结果表明:硫酸盐含量低于2.7%时,固化盐渍土抗压强度随含盐量的增加呈先增大后减小,抗压强度峰值对应的含盐量为1.8%;固化盐渍土的火山灰反应产物主要为C-S-H和AFt,硫酸盐含量从0.3%增至1.8%时,反应产物明显增多,致使固化土抗压强度增大;但当硫酸盐含量从1.8%增至2.7%时,膨胀性AFt将试件内部孔隙完全填充并产生胀裂破坏,造成抗压强度降低。研究成果为全固废材料固化硫酸盐渍土的工程应用奠定了基础,对环境保护也有积极贡献。     

自密实包浆再生混凝土早期塑性开裂试验研究

为了研究包浆再生粗骨料对自密实再生混凝土早期塑性开裂性能的影响,通过正交试验得出混凝土相对最优的配比方案。在此基础上,控制其他因素不变,以包浆水泥强度等级为单一变量,采用平板约束法,进行混凝土早期塑性开裂试验。结果表明:再生粗骨料经过包浆后,混凝土抗压与抗折强度均得到一定的提高;再生混凝土单位面积总开裂面积约为普通混凝土的1.5倍,经过水泥包浆后,开裂面积有了不同程度的减少,与未包浆的相比,32.5R、42.5R、52.5R水泥包浆的混凝土开裂面积分别减少了11.1%、25.1%、13.1%,其中42.5R水泥的包浆效果最好。结合微观电镜试验发现,骨料包浆可加强混凝土的界面过渡区,提高其抗开裂能力。     

Comparison of Representative Heuristic Algorithms for Multi-Objective Reservoir Optimal Operation

Heuristic algorithms (HAs) are widely used in multi-objective reservoir optimal operation (MOROO) due to the rapidity of the calculation and simplicity of their design. The literature usually focuses on one or two categories of HAs and simply reviews the state of the art. To provide an overall understanding and a specific comparison of HAs in MOROO, differential evolution (DE), particle swarm optimisation (PSO), and artificial physics optimisation (APO), which serve as typical examples of the three categories of HAs, are compared in terms of the development and applications using a designed experiment. Besides, the general model with constraints and fitness function, and the solution process using a hybrid feasible domain restoration method and penalty function method are also presented. Taking a designed experiment with multiple scenarios, the mean average of the optimal objective function values, the standard deviation of optimal objective function values, the mean average of the computational time, and population diversity are used for comparisons. Results of the comparisons show that (a) the problem of optimal multipurpose reservoir long-term operation is a mathematic programming problem with narrow feasible region and monotonic objective function; (b) it is easy to obtain the same optimal objective function value, but different optimal solutions using HAs; and (c) comparisons do not result in a clear winner, but DE can be more appropriate for MOROO.

     

干湿循环下膨胀土胀缩性能试验

采用压缩仪和收缩仪,对重塑膨胀土进行了无荷条件下的反复膨胀和收缩试验。试验结果表明:随着干湿循环次数的增加,试样的最终膨胀率和最终收缩率逐渐减小;膨胀变形明显减小,而收缩变形减小的幅度不大;试样的最终高度均呈现减小趋势;收缩系数不断减小,最终趋于稳定;采用绝对膨胀率、相对膨胀率、绝对收缩率和相对收缩率等参数可以合理描述干湿循环作用下膨胀土的胀缩变形特征。     

A dual reciprocity boundary element method for photothermal interactions in laser-induced thermotherapy

Laser-induced thermotherapy (LITT) is a minimally invasive laser hyperthermia procedure for the treatment of localized tumors. Mathematical modeling of the photothermal processes in laser-irradiated tissues is essential for optimal treatment planning. In this study, A Monte Carlo method is introduced to simulate photon transport in the tumor tissues with complex geometries. The dual reciprocity boundary element method (DRBEM) is then formulated to solve the bioheat transfer equation in the tumors. The model is validated with the finite difference solutions. To illustrate the applications of the proposed DRBEM, several laser delivery schemes, including external laser irradiation, single or multiple laser fiber delivery applicators, are studied for tumors with regular or irregular geometric shapes. The temperature transients, laser energy distribution and coagulation patterns for different laser delivery modes are demonstrated. The unique advantages of the DRBEM, such as easy adaptability to complex tumor geometries and no need to discretize the inner domain, may make it well-suited and robust approach for predicting and controlling the temperature evolution in laser-induced thermotherapy procedure.     

Synthesis of ferronickel slag-based geopolymers

This paper deals with the synthesis of geopolymers utilizing ferronickel slag as raw material. The utilized slag is produced in the Greek plant LARCO during the pyrometallurgical treatment of laterites for the production of ferronickel, specifically at the step of the reductive smelting in electric arc furnaces. The performed work includes the optimization of the slag-based geopolymeric system through the study of the effect of the synthesis parameters on the mechanical properties of the produced materials. The structure of geopolymers was determined with X-ray diffractometry (XRD), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The obtained results showed that the ferronickel slag is an excellent raw material for the production of inorganic polymers using the geopolymerization technology. The materials produced under the optimum synthesis conditions were compact and rigid and presented high compressive strength (118 MPa), as well as extremely low water absorption (0.7–0.8%).     

In-cavity evaporation allowance—A drying capacity indicator for wood-frame wall system

Although moisture significantly affects the performance and durability of building envelope systems, effective methods to quantify the relative drying capacity of these systems are yet to be developed. A new testing method and an evaluation approach for comparing the drying capacity of wood-frame wall systems in evacuating water due to rain penetration in the stud cavities are presented in this paper. A controllable and consistent moisture loading is created by placing a water tray on a load cell at the bottom of the stud cavity of the wall assembly which is then subjected to lab generated indoor/outdoor conditions. The data on water evaporation from water trays and the monitored moisture accumulations in the materials surrounding the stud cavities are used to establish load–response relations. Using these relations the relative performance of various building envelope systems in preventing biodeterioration caused by rainwater penetration into the stud cavities can be compared. The concept of in-cavity evaporation allowance (ICEA) has been proposed and it is based on the limit of 20% moisture content (MC) being reached at any location of the building envelope.