Prediction Model-based Multi-objective Optimization for Mix-ratio Design of Recycled Aggregate Concrete

The prediction model for mechanical properties of RAC was established through the Bayesian optimization-based Gaussian process regression(BO-GPR)method,where the input variables in BO-GPR model depend on the mix ratio of concrete.Then the compressive strength prediction model,the material cost,and environmental factors were simultaneously considered as objectives,while a multi-objective gray wolf optimization algorithm was developed for finding the optimal mix ratio.A total of 730 RAC datasets were used for training and testing the predication model,while the optimal design method for mix ratio was verified through RAC experiments.The experimental results show that the predicted,testing,and expected compressive strengths are nearly consistent,illustrating the effectiveness of the proposed method.

A Modified Bi-Directional Evolutionary Structural Optimization Procedure with Variable Evolutionary Volume Ratio Applied to Multi-Objective Topology Optimization Problem

Natural frequency and dynamic stiffness under transient loading are two key performances for structural design related to automotive,aviation and construction industries.This article aims to tackle the multi-objective topological optimization problem considering dynamic stiffness and natural frequency using modified version of bi-directional evolutionary structural optimization(BESO).The conventional BESO is provided with constant evolutionary volume ratio(EVR),whereas low EVR greatly retards the optimization process and high EVR improperly removes the efficient elements.To address the issue,the modified BESO with variable EVR is introduced.To compromise the natural frequency and the dynamic stiffness,a weighting scheme of sensitivity numbers is employed to form the Pareto solution space.Several numerical examples demonstrate that the optimal solutions obtained from the modified BESO method have good agreement with those from the classic BESO method.Most importantly,the dynamic removal strategy with the variable EVR sharply springs up the optimization process.Therefore,it is concluded that the modified BESO method with variable EVR can solve structural design problems using multi-objective optimization.

An Improved Multi-Objective Particle Swarm Optimization Routing on MANET

A Mobile Ad hoc Network(MANET)is a group of low-power con-sumption of wireless mobile nodes that configure a wireless network without the assistance of any existing infrastructure/centralized organization.The primary aim of MANETs is to extendflexibility into the self-directed,mobile,and wireless domain,in which a cluster of autonomous nodes forms a MANET routing system.An Intrusion Detection System(IDS)is a tool that examines a network for mal-icious behavior/policy violations.A network monitoring system is often used to report/gather any suspicious attacks/violations.An IDS is a software program or hardware system that monitors network/security traffic for malicious attacks,sending out alerts whenever it detects malicious nodes.The impact of Dynamic Source Routing(DSR)in MANETs challenging blackhole attack is investigated in this research article.The Cluster Trust Adaptive Acknowledgement(CTAA)method is used to identify unauthorised and malfunctioning nodes in a MANET environment.MANET system is active and provides successful delivery of a data packet,which implements Kalman Filters(KF)to anticipate node trustworthiness.Furthermore,KF is used to eliminate synchronisation errors that arise during the sending and receiving data.In order to provide an energy-efficient solution and to minimize network traffic,route optimization in MANET by using Multi-Objective Particle Swarm Optimization(MOPSO)technique to determine the optimal num-ber of clustered MANET along with energy dissipation in nodes.According to the researchfindings,the proposed CTAA-MPSO achieves a Packet Delivery Ratio(PDR)of 3.3%.In MANET,the PDR of CTAA-MPSO improves CTAA-PSO by 3.5%at 30%malware.

Multi-objective Optimization of a Two-Stage Helical Gearbox to Improve Efficiency and Reduce Height

The goal of this research is to look at multi-target optimization of a two-stage helical gearbox in order to determine the best key design elements for reducing gearbox height and enhancing gearbox efficiency.To do this,the method known as Taguchi and GRA(Grey Relation Analysis)were used in two stages to address the problem.The single-objective optimization problem was addressed first to close the gap between variable levels,and then the multi-objective optimization problem was solved to determine the best primary design variables.The first and second stage CWFWs(Coefficients of Wheel Face Width),ACS(Permissible Contact Stresses),and first stage gear ratio were also calculated.The study’s findings were utilized to identify the best values for five critical design aspects of a two-stage helical gearbox.

Optimization of clay material mixture ratio and filling process in gypsum mine goaf

Because there is neither waste rock nor mill tailings in the gypsum mine, and the buildings on the goaf of gypsum mine are needed to be protected, the research proposed the scheme of the clay filling technology. Gypsum, cement, lime and water glass were used as adhesive, and the strength of different material ratios were investigated in this study. The influence factors of clay strength were obtained in the order of cement, gypsum, water glass and lime. The results show that the cement content is the determinant influence factor, and gypsum has positive effects, while the water glass can enhance both clay strength and the fluidity of the filing slurry. Furthermore, combining chaotic optimization method with neural network, the optimal ratio of composite cementing agent was obtained. The results show that the optimal ratio of water glass, cement, lime and clay (in quality) is 1.17:6.74:4.17:87.92 in the process of bottom self-flow filling, while the optimal ratio is 1.78:9.58:4.71:83.93 for roof-contacted filling. A novel filling process to fill in gypsum mine goaf with clay is established. The engineering practice shows that the filling cost is low, thus, notable economic benefit is achieved.

Optimization of the reflux ratio of benzene-toluene stage distillation columns by the Cuckoo algorithm

In this study, an enthalpy-concentration method was applied in order to model a steady state continuous benzene-toluene mixture distillation column. For a distillation tower such as the benzene- toluene splitter, there are relatively few degrees of freedom that can be manipulated in order to minimize the total annualized cost. The reflux ratio can influence the steady-state operating point and therefore influence the total annualized cost. The trade-offs between reflux ratios and total annualized cost were discussed. The Cuckoo optimization algorithm was applied to obtain a correlation for the optimum value of the reflux ratio as a power function of the economic parameters of energy price and capital cost. The results show that, at low energy price or high capital cost, the optimum reflux factor is high.

Multi-objective robust design optimization of a novel negative Poisson's ratio bumper system

Negative Poisson's ratio(NPR) structure has outstanding performances in lightweight and energy absorption, and it can be widely applied in automotive industries. By combining the front anti-collision beam, crash box and NPR structure, a novel NPR bumper system for improving the crashworthiness is first proposed in the work. The performances of the NPR bumper system are detailed studied by comparing to traditional bumper system and aluminum foam filled bumper system. To achieve the rapid design while considering perturbation induced by parameter uncertainties, a multi-objective robust design optimization method of the NPR bumper system is also proposed. The parametric model of the bumper system is constructed by combining the full parametric model of the traditional bumper system and the parametric model of the NPR structure. Optimal Latin hypercube sampling technique and dual response surface method are combined to construct the surrogate models. The multi-objective robust optimization results of the NPR bumper system are then obtained by applying the multi-objective particle swarm optimization algorithm and six sigma criteria. The results yielded from the optimizations indicate that the energy absorption capacity is improved significantly by the NPR bumper system and its performances are further optimized efficiently by the multi-objective robust design optimization method.

基于响应曲面法确定玄武岩纤维热再生沥青混合料最佳配合比

在进行沥青混合料配合比设计时,由于掺加两种或两种以上掺合物时,采用马歇尔试验法或正交试验法进行沥青混合料配合比存在不足,为了确定沥青混合料最佳配合比,通过基于响应曲面法中的BBD(Box-Behnken design)法对级配类型AC-13掺加玄武岩纤维、RAP的热再生沥青混合料进行级配优化设计。结果表明,计算优化得出最佳油石比为5.17%、旧料掺量RAP为31.89%及玄武岩纤维掺量0.26%。并通过试验对预测模型进行验证,预测值与实测值模型之间相对误差较小(小于3%),可见BBD法建立的二阶模型具有较好的拟合效果,对再生沥青混合料各掺量配合比设计能进行有效优化,并且最佳各掺量下的玄武岩纤维热再生沥青混合料具有良好的路用性能。

超细铁尾矿气泡混合轻质土优化设计研究

目的:为了实现超细铁尾矿在气泡混合轻质土中的高效利用,以最优力学性能为目标,进行了配合比优化设计。方法:基于BBD响应面曲面法,以尾矿掺量15%~30%、泡沫掺量4%~6%、水料比0.4~0.6为变量,以7 d和28 d抗压强度为响应值,设计了17组配合比,并分析了组成因素间的相互作用对抗压强度的影响程度。结果:泡沫掺量对超细铁尾矿气泡混合轻质土抗压强度影响最为显著,其次是水料比和尾矿掺量;从两因素交互作用上看,尾矿掺量和泡沫掺量交互作用对抗压强度影响最为显著;通过对回归模型的极值求解,当尾矿掺量为34.19%、泡沫掺量为4.34%、水料比为0.45时,超细铁尾矿气泡混合轻质土具有最优的力学性能。结论:经优化设计后的超细铁尾矿气泡混合轻质土可满足填筑工程技术要求。

基于体积特性的钢渣沥青混合料最佳油石比等体积设计方法研究

为了建立一种将玄武岩沥青混合料最佳油石比转化为钢渣沥青混合料最佳油石比的设计方法,首先,采用等体积替换法得到钢渣的实际用量;随后,采用CT扫描技术研究了钢渣集料多孔特性对沥青的多余吸附量,从而确定了钢渣的吸附机理,并建立了一种钢渣集料的材料组成设计方法。研究结果表明:粒径为10~15 mm的钢渣集料表面孔内沥青体积占钢渣集料表面实际沥青体积的20.21%;粒径为5~10 mm的钢渣集料表面孔内沥青体积占钢渣集料表面实际沥青体积的6.70%。基于体积特性的材料组成设计方法计算的钢渣沥青混合料最佳油石比为5.79%,与马歇尔击实试验结果基本一致。现场检测结果表明,5.70%油石比摊铺的钢渣沥青路面具有优异的抗滑性能和路用价值,对保障路面行车安全具有突出意义。与玄武岩沥青路面相比,钢渣沥青路面的摆值和横向力系数多分布于数值较高的区域,其具有更加优异的抗滑性能。

水泥-矿渣基早强固化剂制备及固化土宏微观性能研究

为提高工业废渣的利用率,选用磷石膏、高炉矿渣、硅酸钠代替部分水泥并对土样进行固化处理。通过D-最优混料设计,得出3与7 d的无侧限抗压强度回归方程,并计算得到最优质量配合比。使用最优配方固化土样,测得3和7 d无侧限抗压强度分别达4.88和5.84 MPa。通过因素间交互分析结果,得出固化材料的最优掺量范围。通过X射线衍射和扫描电子显微镜对固化土微观机理进行分析,结果表明最优固化土相比水泥固化土水化反应更完全,颗粒间连接更密实,结构更稳定。最后通过对最优配方进行环境效益与经济性评价,得出该配方在强度、环境效益、经济性等方面均要优于水泥。

基于两种方法优化磷酸镁水泥砂浆配合比研究

为优化磷酸镁水泥(MPC)砂浆配合比,对比分析了响应面法(RSM)和反向传播神经网络结合遗传算法(GA-BP)。首先应用旋转中心组合设计进行试验;然后分析镁钾比(M/P)、硼砂含量(B/M)、水胶比(W/C)及粉煤灰含量(FA/C)对MPC凝结时间、1 d抗压强度及1 d抗折强度的影响规律及自变量间的交互作用;最后利用RSM和GA-BP分别对试验结果寻优。结果表明:与RSM相比,GA-BP得到的MPC最优配合比下性能更好,相对误差更小,这为水泥砂浆配合比优化提供新思路。

收益率椭球分布不确定下的均值-CVaR优化研究

The article explores a mean-CVaR ratio model with returns distribution uncertainty.To describe the uncertainty of returns distribution,a mixture ellipsoidal distribution absorbing some typical distributions such as the mixture distribution and and ellipsoidal distribution is introduced.Then,by using robust technique with some assumptions,the original robust mean-CVaR ratio model can be formulated as a second-order cone optimization model where the underlying random returns have a mixture ellipsoidal distribution.As an illustration,the corresponding robust optimization models are applied to allocations of assets in securities market.Numerical simulations are presented to illustrate the relation between robustness and optimality and to compare mixture ellipsoidal distribution to some typical distributions as well.

高速公路中双层乳化沥青厂拌冷再生基层的应用

基于对符合再生要求的材料充分回收利用,节约资源、降低排放及减少传统半刚性基层沥青路面反射裂缝的理念,G30连霍高速郑洛段大修改建工程将传统的半刚性基层替换为偏柔性的双层乳化沥青厂拌冷再生基层结构,通过全新的双层乳化沥青厂拌冷再生路面结构设计、沥青混合料回收料(RAP)性能分析、乳化沥青厂拌冷再生配合比设计、现场取芯与弯沉检测性能验证及乳化剂性能改善,确定并验证了最佳路用性能下的混合料生产配合比。结果表明:当0~10 mm RAP掺量32%,10 mm~30 mm RAP掺量43%,0~5 mm石屑掺量12%,10 mm~30 mm碎石掺量13%,乳化沥青用量4.1%,水泥用量1.8%,最佳含水率为5.2%时,混合料路用性能最佳,其15℃劈裂强度达0.625 MPa;双层乳化沥青厂拌冷再生基层结构对沥青混合料回收料利用率高、经济效益明显。

基于SVM的钢纤维再生混凝土配合比优化

基于支持向量机(SVM)模型对钢纤维再生混凝土立方体的抗压强度进行了预测,得到了其与原材料配合比之间的非线性关系函数。将这个函数作为目标适应度函数,同时引入经济成本作为另一个目标适应度函数,依据规范和工程具体要求,建立了原材料配合比的相关约束条件,利用遗传算法进行了求解,实现了抗压强度和造价两目标优化,得出了最佳配合比集。结果表明:采用SVM模型预测混凝土立方体抗压强度的精度很高,相对误差在6%以内,并利用遗传算法求出了抗压强度和造价的Pareto最优解集。

响应面法优化有机质软土复合固化剂配方

为了改善水泥固化有机质软土的效果,配制出一种专门固化有机质软土的高效复合固化剂,从选择合适的矿物填料,减薄土壤双电层的厚度,提高土壤PH值,增强早期强度,调节水泥离子和黏土颗粒的活性等5个方面选定生石膏,生石灰,碳酸钠,FDN,水玻璃,三乙醇胺等6种添加剂来改善有机质软土的固化.将6种添加剂的质量分数作为影响固化土强度的6个因子,7d龄期的无侧限抗压强度增长率作为响应值,利用响应面法来对添加剂进行优选和配方研究,并考察各影响因子的交互作用规律.结果表明:生石膏,碳酸钠,水玻璃和三乙醇胺对固化土强度增长率的线性效应明显;6种因子对强度增长率的曲面效应都明显;而生石灰和碳酸钠,FDN和水玻璃,以及水玻璃和三乙醇胺对强度增长率有交互作用的影响.最终得出,在腐植酸质量分数为6%,水泥质量与土样质量比为15%的前提下,复合固化剂配方为生石膏质量分数为4.85%,生石灰质量分数为3.79%,碳酸钠质量分数为1.42%,FDN质量分数为1.99%,水玻璃质量分数为5.06%,三乙醇胺质量分数为0.08%,此时固化土7d的强度可以达到1 003kPa.

古尔班通古特沙漠砂混凝土配合比试验研究

利用正交试验方法对新疆古尔班通古特沙漠砂混凝土的工程特性进行了试验研究,考察了水胶比、灰砂比、沙漠砂替代率、粉煤灰掺量和减水剂对沙漠砂混凝土立方体抗压强度、和易性的影响,并对试验结果进行了极差、方差和因素指标分析。试验结果表明,对于混凝土立方体的抗压强度,7 d时各因素的影响顺序为:水胶比>沙漠砂替代率>灰砂比>粉煤灰掺量>减水剂掺量;28 d时各因素的影响顺序为:水胶比>减水剂掺量>沙漠砂替代率>灰砂比>粉煤灰掺量;对于混凝土立方体的和易性,各因素的影响顺序为:水胶比>沙漠砂替代率>灰砂比>减水剂掺量>粉煤灰掺量。综合分析各因素对沙漠砂混凝土抗压强度、和易性的影响,最终确定沙漠砂混凝土的最优配合比。

土石混合体压缩性的三维颗粒力学研究

土石混合体是由作为骨料的砾石或卵石与作为填充料的黏土或砂土组成的特殊工程地质材料,无论天然形成或人工合成,其力学特性与均质土体或岩体相比均有较大差异。以昆明新机场高填方中大量采用土石混合体填料为工程背景,在三维颗粒流程序中对特定的土石混合体试样的侧限压缩试验进行数值模拟,比较了不同级配条件下土石混合体模型的微观结构及基本力学物理性能。通过比较侧限压缩模量和压缩后孔隙率,研究了含石率对土石混合体骨架效应等结构性的影响,并提出了工程中建议采用的土石比例区间,在颗粒流方法用于实际工程方面进行了有益的探索。

青海湖地区燕麦与箭筈豌豆最佳混播比例的筛选

在青海湖南岸的甲乙村以箭筈豌豆(W)和燕麦(Y)以1∶0、1∶1、1∶2和1∶3比例混播,分别对不同时期牧草干草产量、营养品质进行测定,以确定该地区最佳混播比例和收获时间。结果表明:各处理干草产量在2015年9月底最大,干草产量1∶0、1∶1、1∶2和1∶3混播比例分别为1 155.14、1 997.09、1 946.38、1 967.70 g/m^2。箭筈豌豆单播处理(1∶0)干草产量显著低于其他处理(P<0.05),比其他3种混播比例干草产量约低800 g/m^2(约占41%)。混播处理中,随着燕麦比例的增加,干草粗蛋白含量逐渐下降,中、酸性洗涤纤维以及粗脂肪含量比箭筈豌豆单播增大。箭筈豌豆单播处理在8月底粗蛋白产量达到最高值为276.47 g/m^2,显著高于其他处理(P<0.05),分别是混播比例1∶1,1∶2和1∶3粗蛋白产量的1.6倍,1.8倍和2.7倍。箭筈豌豆与燕麦1∶1比例混播9月底粗蛋白产量最高,为364.79 g/m^2,显著高于其他混播,大约是箭筈豌豆单播处理(1∶0)粗蛋白产量的1.5倍,是1∶2混播比例粗蛋白产量的1.4倍,是1∶3混播比例粗蛋白产量的2.4倍。综合干草产量及粗蛋白产量,该地区箭筈豌豆和燕麦的最佳混播比例是1∶1,牧草最佳收获时间是9月底。

玻化微珠再生混凝土保温砌块配合比优化设计

基于总功效系数法,采用正交试验原理与方差分析方法,对掺加玻化微珠的再生混凝土保温砌块的配合比进行优化设计。结果表明:在最佳配合比下,可制备出满足中国标准GB 26538—2011《烧结保温砖和保温砌块》的QGB B(390 mm×240 mm×190 mm)800 Mu5.0 0.30优等产品。为再生混凝土在现代高层建筑中的应用指明了一条途径。