Multiobjective optimization and multivariable control of the beer fermentation process with the use of evolutionary algorithms

This paper describes empirical research on the model, optimization and supervisory control of beer fermentation.Conditions in the laboratory were made as similar as possible to brewery industry conditions. Since mathematical models that consider realistic industrial conditions were not available, a new mathematical model design involving industrial conditions was first developed. Batch fermentations are multiobjective dynamic processes that must be guided along optimal paths to obtain good results.The paper describes a direct way to apply a Pareto set approach with multiobjective evolutionary algorithms (MOEAs).Successful finding of optimal ways to drive these processes were reported.Once obtained, the mathematical fermentation model was used to optimize the fermentation process by using an intelligent control based on certain rules.

Revised barrier function-based adaptive finite-and fixed-time convergence super-twisting control

This paper presents an adaptive gain,finite-and fixedtime convergence super-twisting-like algorithm based on a revised barrier function,which is robust to perturbations with unknown bounds.It is shown that this algorithm can ensure a finite-and fixed-time convergence of the sliding variable to the equilibrium,no matter what the initial conditions of the system states are,and maintain it there in a predefined vicinity of the origin without violation.Also,the proposed method avoids the problem of overestimation of the control gain that exists in the current fixed-time adaptive control.Moreover,it shows that the revised barrier function can effectively reduce the computation load by obviating the need of increasing the magnitude of sampling step compared with the conventional barrier function.This feature will be beneficial when the algorithm is implemented in practice.After that,the estimation of the fixed convergence time of the proposed method is derived and the impractical requirement of the preceding fixed-time adaptive control that the adaptive gains must be large enough to engender the sliding mode at time t=0 is discarded.Finally,the outperformance of the proposed method over the existing counterpart method is demonstrated with a numerical simulation.

Research on Total Electric Field Prediction Method of Ultra-High Voltage Direct Current Transmission Line Based on Stacking Algorithm

Ultra-high voltage(UHV)transmission lines are an important part of China’s power grid and are often surrounded by a complex electromagnetic environment.The ground total electric field is considered a main electromagnetic environment indicator of UHV transmission lines and is currently employed for reliable long-term operation of the power grid.Yet,the accurate prediction of the ground total electric field remains a technical challenge.In this work,we collected the total electric field data from the Ningdong-Zhejiang±800 kV UHVDC transmission project,as of the Ling Shao line,and perform an outlier analysis of the total electric field data.We show that the Local Outlier Factor(LOF)elimination algorithm has a small average difference and overcomes the performance of Density-Based Spatial Clustering of Applications with Noise(DBSCAN)and Isolated Forest elimination algorithms.Moreover,the Stacking algorithm has been found to have superior prediction accuracy than a variety of similar prediction algorithms,including the traditional finite element.The low prediction error of the Stacking algorithm highlights the superior ability to accurately forecast the ground total electric field of UHVDC transmission lines.

Multivariable sales prediction for filling stations via GA improved BiLSTM

Accurate sales prediction in filling stations is the basis to fill in the refined oil in time and avoid the outof-stock as much as possible.Considering the defect of great“lag”in the general time series model,this paper summarizes the multiple factors that influence the oil sales and develops a multivariable long short-term memory(LSTM)neural network,with the hyper-parameters being improved by the genetic algorithm(GA).To further improve the prediction accuracy,the proposed LSTM neural network is generalized to bidirectional LSTM(Bi LSTM),in which the impact of future factors on present sales can be taken into account by backward training.Finally,different LSTM structures and genetic algorithm parameters are tested to discuss their impact on prediction accuracy.Results demonstrated that genetic algorithm improved Bi LSTM model is superior to extreme gradient boosting,ARIMA,and artificial neural network,having the highest accuracy of 89%.

Fractional-Order Super-Twisting Sliding-Mode Procedure Design for a Class of Fractional-Order Nonlinear Dynamic Underwater Robots

The purpose of this study is to design a fractional-order super-twisting sliding-mode controller for a class of nonlinear fractionalorder systems.The proposed method has the following advantages:(1)Lyapunov stability of the overall closed-loop system,(2)output tracking error’s convergence to zero,(3)robustness against external uncertainties and disturbances,and(4)reduction of the chattering phenomenon.To investigate the performance of the method,the proposed controller is applied to an autonomous underwater robot and Lorenz chaotic system.Finally,a simulation is performed to verify the potential of the proposed method.

A Graph Drawing Algorithm for Visualizing Multivariate Categorical Data

In this paper, a new approach for visualizing multivariate categorical data is presented. The approach uses a graph to represent multivariate categorical data and draws the graph in such a way that we can identify patterns, trends and relationship within the data. A mathematical model for the graph layout problem is deduced and a spectral graph drawing algorithm for visualizing multivariate categorical data is proposed. The experiments show that the drawings by the algorithm well capture the structures of multivariate categorical data and the computing speed is fast.

Grid-Based Path Planner Using Multivariant Optimization Algorithm

To solve the shortest path planning problems on grid-based map efficiently,a novel heuristic path planning approach based on an intelligent swarm optimization method called Multivariant Optimization Algorithm( MOA) and a modified indirect encoding scheme are proposed. In MOA,the solution space is iteratively searched through global exploration and local exploitation by intelligent searching individuals,who are named as atoms. MOA is employed to locate the shortest path through iterations of global path planning and local path refinements in the proposed path planning approach. In each iteration,a group of global atoms are employed to perform the global path planning aiming at finding some candidate paths rapidly and then a group of local atoms are allotted to each candidate path for refinement. Further,the traditional indirect encoding scheme is modified to reduce the possibility of constructing an infeasible path from an array. Comparative experiments against two other frequently use intelligent optimization approaches: Genetic Algorithm( GA) and Particle Swarm Optimization( PSO) are conducted on benchmark test problems of varying complexity to evaluate the performance of MOA. The results demonstrate that MOA outperforms GA and PSO in terms of optimality indicated by the length of the located path.

A fast algorithm for multivariate Hermite interpolation

Multivariate Hermite interpolation is widely applied in many fields, such as finite element construction, inverse engineering, CAD etc.. For arbitrarily given Hermite interpolation conditions, the typical method is to compute the vanishing ideal I （the set of polynomials satisfying all the homogeneous interpolation conditions are zero） and then use a complete residue system modulo I as the interpolation basis. Thus the interpolation problem can be converted into solving a linear equation system. A generic algorithm was presented in [18], which is a generalization of BM algorithm [22] and the complexity is O（τ^3） where r represents the number of the interpolation conditions. In this paper we derive a method to obtain the residue system directly from the relative position of the points and the corresponding derivative conditions （presented by lower sets） and then use fast GEPP to solve the linear system with O（（τ ＋ 3）τ^2） operations, where τ is the displacement-rank of the coefficient matrix. In the best case τ = 1 and in the worst case τ = [τ/n], where n is the number of variables.

Application of Multivariate Reinforcement Learning Engine in Optimizing the Power Generation Process of Domestic Waste Incineration

Garbage incineration is an ideal method for the harmless and resource-oriented treatment of urban domestic waste.However,current domestic waste incineration power plants often face challenges related to maintaining consistent steam production and high operational costs.This article capitalizes on the technical advantages of big data artificial intelligence,optimizing the power generation process of domestic waste incineration as the entry point,and adopts four main engine modules of Alibaba Cloud reinforcement learning algorithm engine,operating parameter prediction engine,anomaly recognition engine,and video visual recognition algorithm engine.The reinforcement learning algorithm extracts the operational parameters of each incinerator to obtain a control benchmark.Through the operating parameter prediction algorithm,prediction models for drum pressure,primary steam flow,NOx,SO2,and HCl are constructed to achieve short-term prediction of operational parameters,ultimately improving control performance.The anomaly recognition algorithm develops a thickness identification model for the material layer in the drying section,allowing for rapid and effective assessment of feed material thickness to ensure uniformity control.Meanwhile,the visual recognition algorithm identifies flame images and assesses the combustion status and location of the combustion fire line within the furnace.This real-time understanding of furnace flame combustion conditions guides adjustments to the grate and air volume.Integrating AI technology into the waste incineration sector empowers the environmental protection industry with the potential to leverage big data.This development holds practical significance in optimizing the harmless and resource-oriented treatment of urban domestic waste,reducing operational costs,and increasing efficiency.

基于注意力机制的ADE-Bi-IndRNN模型的中国粮食产量预测

为更加准确地预测我国粮食总产量,基于自适应差分进化算法来智能地选择基于注意力机制的双向独立循环神经网络的超参数,并考虑了粮食作物单位产量、农业生产条件、科技因素、农业保险、市场及经济因素五大类影响因素,构建了基于注意力机制的ADE-Bi-IndRNN粮食产量预测模型。经过预测分析得出我国2020—2024的粮食产量分别为6.67亿吨、6.72亿吨、6.80亿吨、6.99亿吨、7.02亿吨,总体呈现震荡上涨趋势,平均年增长率为1.15%。同时,通过对多个变量进行的注意力权重的分析,发现现阶段对我国粮食总产量预测贡献最大的三个变量为:谷物单位面积产量,粮食作物总播种面积,耕地灌溉面积,且政府对农业保险的政策性补贴、粮食进口量、谷物生产价格指数、农业生产资料指数也有助于提升我国的粮食总产量,并据此对我国粮食行业发展提出了建议。

基于CMMFDE与多传感器信息融合的旋转机械故障诊断研究

采用单一传感器采集的振动信号难以准确描述旋转机械动态特性,导致提取的故障特征无法准确辨识旋转机械故障。针对这一缺陷,提出了一种基于复合多元多尺度波动散布熵(CMMFDE)、多传感器信息融合和哈里斯鹰算法优化极限学习机(HHO-ELM)的旋转机械故障诊断方法。首先,引入复合多元粗粒化处理,提出了CMMFDE方法,避免了传统单变量分析方法只能处理单一通道振动信号而导致特征的表征性能不足的缺陷,增强了故障特征的表征性能;随后,利用布置在旋转机械不同部位的传感器收集了多种类型的信号,组成混合多通道信号,并进行了CMMFDE分析,构建了故障特征;最后,采用HHO对极限学习机的参数进行了自适应优化,并对特征样本进行了训练和测试,完成了旋转机械的故障识别工作;利用齿轮箱、离心泵两种典型的旋转机械数据集进行了实验分析。研究结果表明:该方法对多个通道的信号进行分析时,所获得的准确率达到了100%和98%,优于对单个通道信号进行分析时获得的准确率,同时CMMFDE方法的准确率和特征提取时间均优于精细复合多元多尺度熵(RCMMSE)、精细复合多元多尺度模糊熵(RCMMFE)、精细复合多元多尺度排列熵(RCMMPE)、多元多尺度波动散布熵(MMFDE)。

改进全局ZOA优化MVMD-SCN的锂电池SOH估算

锂电池健康状态(SOH)的准确估算对电池系统的健康管理起着重要作用,为提高SOH的估算精度,提出一种将参数优化后的多元变分模态分解(MVMD)和随机配置网络(SCN)相结合的SOH估算方法。从锂电池充放电过程中提取多个健康因子(HF)作为SOH估算模型的输入,在斑马优化算法(ZOA)全局阶段引入自适应权重和最优领域波动策略,提高其全局搜索能力,得到改进全局的斑马优化算法(IGZOA),利用它对MVMD和SCN参数进行寻优,最后在9个基准函数测试IGZOA性能,在NASA和CALCE数据集上将所提方法与不同方法进行锂电池SOH的估算对比,结果表明,所提方法的均方根误差和绝对误差的平均值分别为0.84%,0.93%,具有更高的预测精度和泛化性。

一种多元均值混合正态分布参数的极大似然估计

以Madadi等提出的数学模型与概率密度函数为基础,证明了多元均值混合正态分布的性质,讨论了MMNE分布参数的极大似然估计问题,利用ECM算法对MMNE分布的位置参数、尺度参数、偏度参数进行了参数估计计算,给出了计算方法和迭代公式。实例分析表明,所提出的偏态数据下MMNE分布参数估计模型合理且实用。

基于核主成分分析和食肉植物算法优化随机森林的风电功率短期预测

为提高风电功率短期预测的精度,提出一种基于核主成分分析和食肉植物算法(carnivorous plant algorithm,CPA)优化随机森林(random forest,RF)的风电功率短期预测方法。首先,利用核主成分分析从13个气象因素中提取出8个与风电功率相关的气象因素,将这8个气象因素输入到预测模型中。然后,利用CPA优化RF构建CPA-RF预测模型解决RF预测模型预测精度不够高的问题。最后,选取实际风电功率数据进行测试,测试结果表明,利用核主成分分析选取8个气象因素作为输入的效果要优于直接输入13个气象因素的效果,CPA-RF预测模型的预测精度高于长短期记忆网络(long short-term memory,LSTM)预测模型、双向长短期记忆神经网络(bidirectional long short-term memory,BiLSTM)预测模型和RF预测模型。该方法可为提升风电功率短期预测精度提供参考。

基于SNV和MSC结合遗传算法对羊肉葡萄糖含量可见-近红外光谱建模的效果

为提高羊肉中营养成分可见-近红外光谱预测模型的稳定性和准确性,本研究以葡萄糖(GLU)指标为例,采用遗传算法(GA)提取特征波长后,结合标准正态变换(SNV)和多元散射校正(MSC)两种预处理方式进行偏最小二乘法建立预测模型,对比SNV、MSC预处理直接进行偏最小二乘的建模效果。结果显示:在标准正态变换下遗传偏最小二乘模型(GA-SNV-PLS)优于直接在标准正态变换下偏最小二乘模型(FS-SNV-PLS);经交叉验证后,该模型的均方根误差(RMSE)为0.122,决定系数(R^(2))为0.930,相对分析误差(RPD)为2.295;相较于全光谱偏最小二乘模型(FSPLS)、全波段多元散射校正FS-MSC-PLS和多元散射下GA-MSC-PLS,其R^(2)和RPD分别提高了95.80%、50.21%、85.05%和62.65%、37.08%、52.54%。结果表明,由SNV结合遗传算法建立的偏最小二乘模型能够提高模型的预测能力。

能量受限的无人机辅助中继通信性能优化

无人机作为中继节点,具有通信距离远、可灵活移动、部署成本低廉等优势。为了提高无人机辅助中继通信性能,同时为了有效利用无人机有限的机载能量,以最大化所有目标节点最小可获得吞吐量为目标,研究了一个能量受限的无人机辅助中继通信网络,提出一种联合任务调度、无人机轨迹规划的多元优化方案。由于原始问题为非凸优化问题难以直接解决,首先将原始问题解耦为两个子问题,然后利用连续凸逼近方法、松弛变量法和块坐标下降法,将非凸优化问题转化为标准凸问题,进而得到两个子问题的次优解。在解决两个子问题的基础上,提出一种多元迭代优化算法从而得到原始问题的次优解。数值仿真结果表明,所提算法具有良好的收敛性,可以有效提高系统的通信性能。

几种基于随钻参数地层识别方法的对比分析

地层岩性的实时识别对及时调整钻井参数、有效控制井眼轨迹、寻找地下储层都具有十分重要的作用。与传统岩性识别方法相比,通过监测随钻参数变化进行岩性识别,具有便捷、高效、实时、准确、环保以及节能等优点。围绕基于随钻参数的地层岩性识别技术,按照煤矿勘探、油气藏开采等不同岩性识别应用领域对随钻参数进行分类;通过对随钻测控技术及装备的研究现状分析,介绍随钻参数采集及传输技术;介绍了机器学习算法、多元统计分析法、灰色关联法、交会图法的特点及应用情况;结合应用案例对4种基于随钻参数的地层识别方法进行对比分析。最终,归纳总结了随钻岩性识别研究的关键技术问题,分析了在研发及工程应用中存在的不足及面临的挑战,并给予建议。

基于t-SNE的多参数岩体结构面分步聚类方法

结构面聚类是进行岩体稳定性评价的重要步骤。常用聚类方法多以产状作为分组依据,忽略了结构面物理特性指标对岩体稳定性的影响。针对分组依据单一化的不足,综合考虑结构面倾向、倾角、迹长、张开度、填充状态和粗糙度的影响,提出一种基于学生分布随机邻近嵌入(student-distributed stochastic neighbor embedding,简称t-SNE)的多参数岩体结构面分步聚类方法。首先,利用t-SNE算法对除产状外的结构面特征进行数据降维;进而利用模拟退火算法搜索K-means算法的全局最优初始值,并采用分步聚类思想完成聚类。研究表明:所提方法有效地解决了高维空间样本稀疏的问题,同时保留了数据的局部结构与全局结构。新方法相比于传统方法能对空间分布相似区内结构面的物理特性进行精确划分,分组精度更高,且在避免复杂权重值计算的条件下,能有效区分产状与物理特性参数对岩体稳定性的影响差异。最后,将所提方法应用于中国新疆某露天矿坡结构面实测数据分析中,所得分组结果合理可靠,进一步证明该方法在实际工程中的有效性。研究方法可为多参数岩体结构面的分步聚类提供参考。

多元混合正态分布参数的极大似然估计

从层次结构的角度出发推导总结了Reinaldo B.Arellano-Vall所提出的广义多元混合正态分布公式中混合变量的相关统计性质,结合所推导的混合变量性质,运用EM算法和协方差矩阵参数化分解方法,解决多元混合正态分布在无序约束和简单树半序约束下参数的极大似然估计问题。借助MATLAB软件编程进行数据仿真模拟,并给出其协方差矩阵在简单树半序约束下的极大似然估计结果。

基于樽海鞘群算法的床温多变量系统辨识研究

针对热工系统具有多输入多输出的特点,介绍将多输入多输出系统简化为多个多输入单输出系统的具体过程。利用机组的实际运行数据,建立在50%负荷运行工况下,以给煤量、煤泥量和一次风量为输入,以床温和主蒸汽压力为输出的多变量系统模型。为提高模型参数辨识的精度,采用樽海鞘群算法(SSA)对多变量系统的模型参数进行寻优。该算法采用一种新的群体更新模型,算法流程简单。仿真结果表明,相比于传统粒子群算法(PSO),樽海鞘群算法运算速度明显提高,可以获到更优的辨识模型。