Sequencing Mixed-model Production Systems by Modified Multi-objective Genetic Algorithms

As two independent problems,scheduling for parts fabrication line and sequencing for mixed-model assembly line have been addressed respectively by many researchers.However,these two problems should be considered simultaneously to improve the efficiency of the whole fabrication/assembly systems.By far,little research effort is devoted to sequencing problems for mixed-model fabrication/assembly systems.This paper is concerned about the sequencing problems in pull production systems which are composed of one mixed-model assembly line with limited intermediate buffers and two flexible parts fabrication flow lines with identical parallel machines and limited intermediate buffers.Two objectives are considered simultaneously：minimizing the total variation in parts consumption in the assembly line and minimizing the total makespan cost in the fabrication/assembly system.The integrated optimization framework,mathematical models and the method to construct the complete schedules for the fabrication lines according to the production sequences for the first stage in fabrication lines are presented.Since the above problems are non-deterministic polynomial-hard（NP-hard）,a modified multi-objective genetic algorithm is proposed for solving the models,in which a method to generate the production sequences for the fabrication lines from the production sequences for the assembly line and a method to generate the initial population are put forward,new selection,crossover and mutation operators are designed,and Pareto ranking method and sharing function method are employed to evaluate the individuals＇ fitness.The feasibility and efficiency of the multi-objective genetic algorithm is shown by computational comparison with a multi-objective simulated annealing algorithm.The sequencing problems for mixed-model production systems can be solved effectively by the proposed modified multi-objective genetic algorithm.

Production Management Modelling Based on MAS

Modelling based on multi-agent system （MAS） was built for the current production management and process of Shenyang Songyang Paper Cup Co., Ltd. It can transmit the information instantly via order agent （OA）, manager agent （MA）, production agent （PA）, and service agent （SA）, and realize information sharing. The PA is also built on MAS, and it includes two agents, task agent （TA）, and resource agent （RA）. It has been found that the modelling is superior to the old one. It can improve the working flow and production efficiency, and shorten the time of delivery.

Experimental Research on Multi-lateral Wells by the Electric Field Analogue Model

There is a close theoretical similarity between water pressure gradients in aquifers and applied voltage gradients in aqueous solutions. A series of electric field analogue experiments has been conducted by focusing on symmetrical multi-lateral wells and dual-lateral wells of arbitrary angles between laterals. This research not only evaluates the productivity equations of a symmetrical multi-lateral well showing the effect of angles on productivity, but also proposes the concept of the multi-lateral productivity coefficient. Moreover, the multi-lateral productivity coefficient equation is designed to calculate the productivity of dual-lateral wells of variable angles, which is in turn supported by experiment. It also helps provide the experimental basis for optimizing the configuration, and building the semi-analytic productivity model, of multi-lateral wells.

Top-level modeling theory of multi-discipline virtual prototype

Multi-disciplinary virtual prototypes of complex products are increasingly and widely used in modern advanced manufactur- ing. How to effectively address the problems of unified modeling, composition and reuse based on the multi-disciplinary heteroge- neous models has brought great challenges to the modeling and simulation （M＆S） science and technology. This paper presents a top-level modeling theory based on the meta modeling framework （M2F） of the COllaborative SIMulation （COSlM） theory of virtual prototyping to solve the problems. Firstly the fundamental prin- ciples of the top-level modeling theory are decribed to expound the premise, assumptions, basic conventions and special require- ments in the description of complex heterogeneous systems. Next the formalized definitions for each factor in top level modeling are proposed and the hierarchical nature of them is illustrated. After demonstrating that they are self-closing, this paper divides the top- level modeling into two views, static structural graph and dynamic behavioral graph. Finally, a case study is discussed to demon- strate the feasibility of the theory.

STATE SPACE MODELING OF DIMENSIONAL MACHINING ERRORS OF SERIAL-PARALLEL HYBRID MULTI-STAGE MACHINING SYSTEM

The final product quality is determined by cumulation, coupling and propagation of product quality variations from all stations in multi-stage manufacturing systems （MMSs）. Modeling and control of variation propagation is essential to improve product quality. However, the current stream of variations （SOV） theory can only solve the problem that a single SOV affects the product quality. Due to the existence of multiple variation streams, limited research has been done on the quality control in serial-parallel hybrid multi-stage manufacturing systems （SPH-MMSs）. A state space model and its modeling strategies are developed to describe the multiple variation streams stack-up in an SPH-MMS. The SOV theory is extended to SPH-MMS. The dimensions of system model are reduced to the production-reality level, and the effect and feasibility of the model is validated by a machining case.

Establishment of a multi-cycle generalized Weng model and its application in forecasts of global oil supply

Low oil prices under the influence of economic structure transformation and slow economic growth have hit the existing markets of traditional big oil suppliers and upgraded the conflict of oil production capacity and interest between OPEC producers and other big oil supplier countries such as the USA and Russia. Forecasting global oil production is significant for all countries for energy strategy planning, although many past forecasts have later been proved to be very seriously incorrect. In this paper,the original generalized Weng model is expanded to a multi-cycle generalized Weng model to better reflect the multi-cycle phenomena caused by political, economic and technological factors. This is used to forecast global oil production based on parameter selection from a large sample, depletion rate of remaining resources, constraints on oil reserves and cycle number determination. This research suggests that the world will reach its peak oil production in 2022, at about 4340×10~6 tonnes. China needs to plan for oil import diversity, a domestic oil production structure based on the supply pattern of large oil suppliers worldwide and the oil demand for China＇s own development.

Econometric analysis of the impacts of climate change on the livestock production in Qinghai Province

This study aims to investigate the effect of the impact mechanism of climate change on the livestock production at small watershed level and county level with the Multi-level Model(MLM)in Qinghai Province.The result indicated that the gross livestock output value was greatly influenced by the climatic factors of the small watershed level.Higher temperature promoted also by the increase of precipitation,relative humidity and sunshine duration was found to be beneficial to the development of livestock production,except in some areas where temperature rise restrained the development of local livestock production to some degree when exceeding a certain level;besides,the impact of the socioeconomic factors on the livestock output value is obvious at the county level.The gross economic output measured with GDP has some inhibitory effects on the reinvestment of livestock production,while population growth promotes development of livestock production to some degree.The results not only provide scientific basis for the management of livestock production in Qinghai Province,but also provide reference for formulating the policies and adaptation measures targeted at climate change to promote the sustainable development of livestock production in other regions.

基于Multi-Stage DEA模型的中国细羊毛生产技术效率实证分析

以内蒙古等4省区为例，采用基于规模报酬可变假设的产出主导型Muhi-StageDEA模型，对2001～2010年中国细羊毛生产技术效率进行了测算和分析。研究结果表明，中国细羊毛生产技术效率不高，存在显著的技术效率损失；细羊毛生产在总体上出现了纯技术效率下降和规模效率提高并存的现象，2008年以来纯技术效率提高对细羊毛生产技术效率改善的促进作用逐渐增强，而细羊毛生产规模效率则呈现出了一定的下降趋势；各省区细羊毛生产技术效率存在较大差异，细羊毛生产的规模效率均要高于纯技术效率，规模效率仍是影响各省区细羊毛生产技术效率改善和提高的主要因素。最后提出改善和提高中国细羊毛生产技术效率的政策建议。

基于Multi-Agent的制造执行系统的生产控制研究

通过对制造执行系统(Manufacturing Executing System,MES)制造模式研究的基础上,应用"漏斗模型"的基本思想,引入多代理技术构建了制造执行系统的新生产控制模型,从而更好的实现计划与控制的衔接,提高企业生产控制的精度。

特色农产品销售评价大数据的弱监督分析方法

针对特色农产品评价大数据多维度分析中,可信标签不足以及挖掘消费者各维度真实情感语义困难等问题。该研究提出了一种基于弱监督训练的深度学习方法。首先,通过主题模型分析大规模评论,提取产品评价主题和关键词。然后,结合句法依存和情感词典为评论生成不同维度的伪标签。最后,构建多标签多分类深度网络,在伪标签上进行弱监督学习。结果表明,该方法在红心柚评论数据集上取得89.2%的准确率和80.3%的F1值,比随机森林算法提升了7.1个百分点的准确率和11.5个百分点的F1值。相比Transformer模型,准确率提高5.6个百分点,F1值提高2.0个百分点,参数量减少了92%。该方法能从海量评论中高效提取产品评价维度和消费者关注点,为完善农产品质量和销售服务提供数据支持。

用户偏好-制造商偏好双重视阈下的产品创新机会识别路径研究

精准识别产品创新机会对制造商规避盲目创新风险,持续获取竞争优势至关重要。针对现有产品创新机会识别研究中因视角单一致使制造商价值创造的效率难以最大化,以及识别的创新机会聚焦度不清晰等诸多问题,基于用户偏好制造商偏好双重视阈构建了产品创新机会识别路径。首先,运用结构主题模型从用户在线评论和产品描述文本中分别提取用户偏好及制造商偏好的产品属性主题;其次,基于两类主题之间的相似度进行主题分类以获取具象产品的创新需求;再次,从现有相关专利中提取创新要素并依托多维技术创新地图识别产品创新机会;最后,以老年智能手环靶向开展产品创新机会识别为例,验证了所提路径的可行性。应用结果表明,构建的用户偏好制造商偏好双重视阈下的产品创新机会识别路径能够为制造商高效开展产品创新活动提供可资借鉴的决策理论支持。

基于多链存储优化的水产品交易匹配模型研究

区块链技术应用到水产品线上交易架构中可以使交易双方隐私信息得到基本保障,然而,目前区块链水产品线上交易模型和系统存在海量数据存储负载大、维护成本高、数据查询效率低等问题。为进一步缓解以上问题,在梳理和分析水产品交易流程基础上,根据水产品交易业务技术需求,提出了基于多链存储优化的水产品交易匹配模型。该模型在智能合约中通过贪心算法实现了效率较高的多属性水产品线上交易匹配过程,通过区块链多通道技术构建了水产品交易多链架构,实现了用户交易信息分布式存储,提高了交易信息查询效率,同时,采用区块链与本地数据库双模式存储技术,缓解了区块链网络中各个节点海量数据存储的负载。基于Hyperledger Fabric平台实现了基于多链存储优化的水产品交易原型系统。该原型系统测试结果表明,临界值900s平均最多可以完成1296笔交易,说明系统在处理千条交易数据量时可以正常运行,满足水产品线上交易平台日常实际交易业务需求,同时在链上存储1600条合同信息时查询1条用户合同信息平均时间为4.018s,多链存储结构提高了链上数据查询速度。

中国新质生产力多因素交互效应研究

加快形成和发展新质生产力既是我国当下关注的关键议题,也是亟须探究的重要命题。基于中国30个省(区、市)面板数据,本文构建广义相加模型(GAM)探讨创新生产力、技术生产力、资源节约型生产力、环境友好型生产力、数字产业生产力和产业数字生产力对新质生产力水平的因素交互影响效应。研究表明:各因素对新质生产力均具有非线性正向效应;多因素共同影响新质生产力且存在非线性交互作用,其中资源节约型生产力是主导影响因素;因素间的交互效应对新质生产力的影响存在显著差异,创新生产力、数字产业生产力与其他因素结合时产生的影响差异最为明显。基于此,提出促进新质生产力发展的相关启示。本文研究有利于拓展新质生产力提升路径的理论研究,为政府制定发展政策提供参考。

为什么国家严控撤县设区:基于粮食安全的新解释

撤县设区是我国推进新型城镇化建设的重要行政区划调整政策。但2021年以来,国家多次表态要严控撤县设区。将撤县设区政策视为准自然实验,基于2000—2019年县域经济社会数据,运用多期DID、PSM-DID、CMP模型、中介效应模型等分析了撤县设区政策对粮食生产和粮食安全的影响及作用机制,从粮食安全视角对国家严控撤县设区的合理性进行了论证。研究发现:首先,撤县设区政策不利于粮食生产和粮食安全,这一结论在更换回归模型、更换被解释变量、调整样本量等检验后仍然稳健,而且这种负面影响存在长期性;其次,撤县设区政策通过农业生产要素重新配置和“政府注意力”转移两个方面对粮食安全产生负面影响;最后,这种负面影响还存在地区异质性,撤县设区对非粮食生产核心区的负面影响更加显著,导致粮食安全责任进一步失衡。建议谨慎推进撤县设区,平衡不同省份粮食安全责任,有序推进县域粮食综合生产能力提升。

中国蛋鸡饲养绿色全要素生产率实证研究

为提高蛋鸡生产效率的同时减少污染排放,在考虑负向产出以及规模异质性和地区异质性的前提下,对蛋鸡养殖绿色全要素生产率(LHBG)进行测度。构建3层次SBM-MML指数,并将其分解为规模结构效率、技术效率以及管理效率。结果表明,2004-2018年平均LHBG为0.9967;大中小规模LHBG分别为0.9949、1.0013、0.9938;东中西部地区LHBG分别为0.9930、0.9980、1.0040。我国蛋鸡饲养绿色全要素生产率总体下降0.33%;规模上中规模最高、大规模其次、小规模最低;区域上西部最高,中部其次,东部最低;其分解效率表现为规模结构效率和技术效率提高,管理效率下降。

基于图文多模态融合推理的产品创新方案设计方法研究

目的针对当前产品创新设计领域中对基于图像-文本多模态知识支撑创新设计方法研究不足的问题,提出了一套基于图文多模态的产品创新方案设计方法。方法首先,对设计师的设计草图与文本要求进行预处理,然后引入产品设计知识图谱来促进设计思维的发散和创新;其次,通过微调的生成式预训练变换器模型和扩散模型生成产品方案及其概念图;最后,利用深度多模态设计评估模型对产品设计方案的可行性和市场潜力进行评估。结果通过产品设计知识图谱,及深度多模态设计评估模型的引入,该设计流程可以生成富有创新性且具备可行性的产品方案。结论基于图文多模态的产品创新方案设计流程结合了最新的深度学习技术,不仅提高了设计的效率,还为设计师提供了更广阔的创新视角和灵感来源。

广州市“三生”空间冲突测度及模拟研究

随着社会经济的快速发展,多功能国土空间之间的冲突日益增强,测算“三生”空间(即“生产—生活—生态”空间)冲突水平,对区域协调发展、土地资源合理配置和生态文明建设具有参考意义。本文以广州市为研究对象,借助多期土地利用数据,总结2000—2020年广州市“三生”空间变化特征,采用空间冲突测度模型和未来土地利用模拟,计算和预测广州市2000—2030年“三生”空间冲突的演变特征和趋势。结论如下:(1)2000—2020年广州市生活生产空间面积占比大幅度上升,生产生态空间和生态生产空间面积占比都呈现下降趋势,生态空间面积呈现小幅度波动变化;(2)2000—2020年,广州市强空间冲突数量占比逐渐增加,空间冲突水平呈上升趋势;(3)2030年自然发展情景、生态优先情景和综合发展情景下广州市的空间冲突水平均显著上升,强空间冲突主要围绕中心城区扩张,且呈现东多西少、南多北少的特征;(4)根据综合发展情景下2030年广州市“三生”空间冲突分布情况,将广州市国土空间划分为五个功能区,并分区提出加强生态保护力度、积极实施生态修复,守好耕地红线、持续提升农业生态效益,优化城市空间结构,推动新型城镇化发展的对策建议。

基于PLUS模型的大连市“三生”空间时空演变与多情景模拟

通过构建“三生”空间分类体系,借助土地利用转移矩阵和PLUS模型探究并预测大连市“三生”空间的时空演变特征,为评估国土空间状况和制定协调开发措施提供有效支持。结果表明:①大连市“三生空间”多功能性显著,生产主-生态副-生活次和生态主-生产副空间分布最广,占比分别为40%、30%。②2000-2020年,生活主-生产副和生态主-生产副空间分别增加592 km^(2)和491 km^(2);生产生态均衡-生活副空间减少了921 km^(2);其余空间较稳定,呈现先增后减规律。③2030年自然发展情景相对稳定需注意耕地减少带来的粮食安全问题;经济优先情景生态风险增加,需建立监测机制;生态保护情景提高了生态空间占比,但需平衡生态要素的结构及经济、社会、环境的整体效益。研究可为大连市国土空间规划提供一定的参考。

ESG评级与企业绿色技术创新——基于多期DID模型的实证研究

企业绿色技术创新是市场微观主体发展绿色生产力、推动高质量发展的重要路径。ESG评级减少了企业与投资人之间的信息不对称,相对于以往的环境规制和政策激励,能够以一种“自下而上”的机制促进企业绿色技术创新。本文以2012~2022年A股上市公司为样本,将企业参与ESG评级这一事件作为事件冲击,运用多期双重差分模型实证检验ESG评级对企业绿色技术创新的影响和作用机制。研究发现:ESG评级能够显著促进企业的绿色技术创新,考虑到内生性问题和经过一系列稳健性检验后结论仍然成立。机制研究表明,ESG评级主要通过缓解企业融资约束、提升企业研发投入和缓解管理者短视问题3个路径促进企业绿色技术创新。异质性研究发现,ESG评级对企业绿色技术创新的促进作用在非重污染企业和国有企业中更明显。本文研究在理论上厘清了ESG评级这一非正式环境规制与企业绿色技术创新之间的关系,在实践上为更好激励企业绿色技术创新提供了经验证据。

基于新能源消纳的高温电解制氢系统建模与控制方法研究

基于新能源随机波动以及低温电解制氢系统转化效率较低且无法切换到发电状态,提出一种高温电解制氢变负载情形下的高效最大产氢点多模型优化控制方法。首先构建计及辅助设备在内的高温固体氧化物电解系统整体协同运行的多能耦合优化模型,分析其影响系统电解的工作温度、电流强度、物料流速等诸多因素并导出高能安全产氢率;其次,在PID控制的基础上,给出一种既能实现变负荷同步准确跟踪产氢轨迹和优化电网调控需求,又能最大优化产氢效率的自适应时变线性变参数模型预测控制方法;最后,通过算例仿真验证所提方法较PID控制电解系统升温速率快,过渡时间短,电解电流、水蒸气流速、H2流速、电炉功率都能平稳过渡至稳态点,具有一定的理论和实用价值。