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Optimal production lot size with process deterioration under an extended inspection policy

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Journal of Systems Engineering and Electronics 2009年第4期20卷 768-776页

作者： Hu fei xu Genqi Ma Lixia Dept. of Mathematics Tianjin Univ. Tianjin 300072 P. R. China

A mathematical model to determine the optimal production lot size for a deteriorating production system under an extended product inspection policy is developed. The last-K product inspection policy is considered so that the nonconforming items can be reduced, under which the last K products in a production lot are inspected and the nonconforming items from those inspected are reworked. Consider that the products produced towards the end of a production lot are more likely to be nonconforming, is proposed an extended product inspection policy for a deteriorating production system. That is, in a production lot, product inspections are performed among the middle K1 items and after inspections, all of the last K2 products are directly reworked without inspections. Our objective here is the joint optimization of the production lot size and the corresponding extended inspection policy such that the expected total cost per unit time is minimized. Since there is no closed form expression for our optimal policy, the existence for the optimal production inspection policy and an upper bound for the optimal lot size are obtained. Furthermore, an efficient solution procedure is provided to search for the optimal policy. Finally, numerical examples are given to illustrate the proposed model and indicate that the expected total cost per unit time of our product inspection model is less than that of the last-K inspection policy.

关键词： production lot size product inspection policy deteriorating production system economic manufacturing quantity.

政务服务标准化改革的协作治理难题与优化——基于“SMBI”框架的分析

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公共管理与政策评论 2025年第1期14卷 25-37页

作者：许飞孔繁斌南京大学政府管理学院

政务服务标准化是建设人民满意的服务型政府重点问题。文章通过引入“结构—机制—行为—互动”(SMBI)框架,结合S省N市政务服务标准化改革历程,对比省、市、区县面对标准化改革不同的态度和做法,指出政务服务部门事权的差异化配置是政... 详细信息

政务服务标准化是建设人民满意的服务型政府重点问题。文章通过引入“结构—机制—行为—互动”(SMBI)框架,结合S省N市政务服务标准化改革历程,对比省、市、区县面对标准化改革不同的态度和做法,指出政务服务部门事权的差异化配置是政务服务标准化改革出现协作治理难题的重要原因之一。在此基础上,标准化与绩效考核机制的强关联性易导致改革成为组织“自我证明”的工具,增添基层政务服务部门工作负担并加剧政府间关系矛盾。然而,基层官员却能通过更多地与公众接触,率先突破科层权威寻求创新变通,推动服务型政府发展。政务服务标准化在实践中同时具备技术工具和行政过程两种属性,要以“积极辅从性”为原则协调政府间矛盾,加强政务服务部门与外界的联系。本文在分析政务服务标准化过程中增添了中观结构、机制和微观行为、互动对改革影响的讨论,研究组织制度设计和个体行为的关系,有助于更加真实地把握标准化这一行政改革工具。

关键词：标准化政务服务绩效考核服务型政府行为公共管理

Some topics on the smooth particle hydrodynamics method

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Acta Mechanica Sinica 2023年第2期39卷 1-2页

作者： fei xu Renato Vacondio School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China Department of Engineering and Architecture University of ParmaParmaItaly

The smooth particle hydrodynamics(SPH)method is one of the earliest meshfree methods,first proposed in 1977[1,2],to solve astrophysical *** the past years,as a Lagrangian,particle method,the SPH method has been widely applied in computational engineering *** provides novel insights for solving complex problems in fluid dynamics and solid mechanics involving large deformations.

关键词： problems. particle hydrodynamics

Realization of Numbers As the Degrees of Maps between Manifolds

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Acta Mathematica Sinica,English Series 2010年第8期26卷 1413-1424页

作者： Young Min LEE fei xu Department of Mathematics Seoul National University Seoul 151747 Republic of Korea School of Mathematics Capital Normal University Beijing 100048 P. R. China

We determine the set of degrees between some classes of oriented closed （n - 1）-connected 2n-manifolds by using the arithmetic theory of quadratic forms.

关键词： Oriented closed manifold degree of a map integral quadratic form

Variation of Out-of-Plane Constraint and Its Effects on Fracture

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上海交通大学学报 2004年第Z2期38卷 212-216页

作者： fei xu Yulong Li Wanlin Guo Department of Mechanical Engineering Tokyo University of Science Noda2788510 Japan School of Aeronautics Northwestern Polytechnical University Xi''an710072 P. R. China School of Aeronautics Northwestern Polytechnical University Xi''an710072 P. R. China School of Aeronautics and Astronauts Nanjing University of Aeronautics and AstronautsNaniing210016 P.R.China

The limitations of using one-parameter to describe the crack-tip fields have prompted investigators to consider better descriptions of the crack tip fields. The two-parameter descriptions, such as J-Q theory, have been an important development in this field. But under the consideration of plane strain and three-dimensional problem, the effects of the out-of-plane stress can not be neglected In this paper, effects of the in-plane constraint as well as the out-of-plane constraint are studied by aid of the finite element method on the plane strain condition. It is obvious that both the in-plane constraint (Q factor) and the out-of-plane constraint (Tz = σzz/(σxx + σyy) ) affect the crack tip *** important features of the out-of-plane constraint are described out based on the simulation results. At the end of this paper, a three-parameter formulation is proposed, in which both the in-plane constraint and the out-of-plane constraint are considered. Comparing with the results of the FEM numerical simulation, the three-parameter description can provide a better prediction near the crack tip.

关键词： in-plane constraint out-of-plane constraint three-parameter formulation crack tip field elastic-plastic

垃圾渗滤液膜浓缩液全量化处理中溶解性有机物分子水平转化特征

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工业水处理 2025年第2期45卷 109-117页

作者：钟全发钟琳徐国徽金青海余瑾徐飞何頔广东工业大学生态环境与资源学院大湾区城市环境安全与绿色发展教育部重点实验室广东广州510006 中国石油天然气股份有限公司吉林油田分公司红岗采油厂吉林白城131301 深圳市盘古环保科技有限公司广东深圳518055

为探究垃圾渗滤液膜浓缩液在全量化处理过程中溶解性有机物(DOM)的去除和转化规律,以深圳某垃圾中转站渗滤液膜浓缩液作为研究对象,利用光谱和高分辨质谱技术全面表征了DOM在宏观和微观层面的转化特征。该中转站采用“生化+高级氧化+生... 详细信息

为探究垃圾渗滤液膜浓缩液在全量化处理过程中溶解性有机物(DOM)的去除和转化规律,以深圳某垃圾中转站渗滤液膜浓缩液作为研究对象,利用光谱和高分辨质谱技术全面表征了DOM在宏观和微观层面的转化特征。该中转站采用“生化+高级氧化+生化”的全量化处理工艺,处理后膜浓缩液色度明显降低,COD和DOC去除率均可达90%以上。紫外可见光谱表明,DOM的芳香性经生化处理后略有提高,而经紫外光/Fenton处理后又显著降低。三维荧光光谱-平行因子分析表明,膜浓缩液中荧光物质以腐殖质和黄腐酸为主,所识别出的4种荧光组分在经全量化工艺处理后可被完全去除。静电场轨道阱质谱分析表明,膜浓缩液DOM以CHO物质以及木质素/富羧基脂环类物质为主,其质量分数分别可达61%~66%和67%~72%。一生化工艺对DOM的去除及转化作用有限,处理过程中仅观察到少量有机物的去除和生成。紫外光/Fenton工艺作为全量化处理中的核心技术可大量去除有机污染物,且所去除的物质主要集中在更低氧化度区域[n(O)/n(C)0.6]。二生化工艺处理能继续去除有机物,并且仅观察到少量产物生成。

关键词：垃圾渗滤液膜浓缩液全量化处理生化处理高级氧化溶解性有机物

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Cure of a New Type Composite on Noise Control and Effect of Filler Modification

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Journal of Materials Science & Technology 2003年第z1期19卷 135-136页

作者： Jun CAI fei xu Weimin CAI School of Municipal and Environment Englineering Harbin Institute of Technology Harbin150001china School of Environment Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Environment Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China

A new type composite of high efficiency sound attenuation was cured. The superfine tungsten powder, plasticizerand stabilizer are added into the PVC resin and blended in the mixing chamber of a HAAKE rheometer. The effect ofthe filler modification is considered in the composite cure. The properties of modified composite and unmodified oneare studied by SEM morphology viewing, acoustic and mechanical measurement. The test results indicate that thereason of the better soundproof and mechanical properties is the particle uniform dispersion and stronger adhesion.

关键词： Composite, Filler modification, Soundproof property, Mechanical property

Molecular dynamics study on surface formation and phase transformation in nanometric cutting of β-Sn

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Advances in Manufacturing 2022年第3期10卷 356-367页

作者： Zhi-Fu xue Min Lai fei-fei xu Feng-Zhou Fang State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro-Nano Manufacturing TechnologyTianjin UniversityTianjin 300072People's Republic of China

Atomic motion and surface formation in the nanometric cutting process ofβ-Sn are investigated using molecular dynamics(MD).A stagnation region is observed that changes the shape of the tool edge involved in nanometric cutting,resulting in a fluctuation in the cutting *** is found that single-crystal tin releases the high compressive stress generated under the tool pressure through slip and phase *** tin transformation proceeds from aβ-Sn structure to a bct-Sn *** effects of the cutting speed,undeformed chip thickness(UCT)and tool edge radius on material removal are also explored.A better surface is obtained through material embrittlement caused by a higher *** addition,a smaller UCT and sharper tool edge help reduce subsurface damage.

关键词： β-Sn Molecular dynamics(MD) Nanometric cutting Surface formation Phase transformation

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基于TD3的无人机计算卸载算法

计算机系统应用 2025年第2期34卷 37-48页

作者：徐飞赵前奔杨雪西安工业大学计算机科学与工程学院西安710021

无人机(unmanned aerial vehicle,UAV)搭载边缘服务器构成移动边缘服务器,可以在一些基站难以部署的场景下为用户设备(user equipment,UE)提供计算服务,借助深度强化学习对智能体进行训练,能够在连续复杂的状态空间中制定合理的卸载决策... 详细信息

无人机(unmanned aerial vehicle,UAV)搭载边缘服务器构成移动边缘服务器,可以在一些基站难以部署的场景下为用户设备(user equipment,UE)提供计算服务,借助深度强化学习对智能体进行训练,能够在连续复杂的状态空间中制定合理的卸载决策,将用户产生的计算密集型任务部分卸载至边缘服务器处执行,提高系统的续航和响应时间.但目前的深度强化学习算法所使用的全连接神经网络无法较好地处理UAV辅助移动边缘计算(mobile edge computing,MEC)场景下的时间序列数据,算法的智能体训练效率低,决策性能差.针对上述问题,本文以最小化UAV辅助MEC系统总时延为目标,提出了一种基于长短期记忆网络的双延迟深度确定性策略梯度算法(twin delayed deep deterministic policy gradient algorithm based on long short term memory,LSTM-TD3).利用LSTM改进TD3算法的Actor-Critic网络结构,将网络划分成3部分:包含LSTM的记忆提取单元,当前特征提取单元,以及感知整合单元;并在改进了经验池中的样本数据,定义了历史数据,使记忆提取单元能够得到更好的训练效果.仿真结果表明,与AC算法、DQN算法和DDPG算法相比,LSTM-TD3算法在以系统最小总时延为目标对卸载策略进行优化时具有最好的性能.

关键词：移动边缘计算无人机深度强化学习计算卸载