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Two-level uncapacitated lot-sizing problem considering the financing cost of working capital requirement

Yuan BIAN, David LEMOINE, Thomas G. YEUNG, Nathalie BOSTEL

《工程管理前沿（英文）》 2020年第7卷第2期页码 248-258 doi: 10.1007/s42524-019-0069-5

摘要： During financial crisis, companies constantly need free cash flows to efficiently react to any uncertainty, thus ensuring solvency. Working capital requirement (WCR) has been recognized as a key factor for releasing tied up cash in companies. However, in literatures related to lot-sizing problem, WCR has only been studied in the single-level supply chain context. In this paper, we initially adopt WCR model for a multi-level case. A two-level (supplier–customer) model is established on the basis of the classic multi-level lot-sizing model integrated with WCR financing cost. To tackle this problem, we propose sequential and centralized approaches to solve the two-level case with a serial chain structure. The ZIO (Zero Inventory Ordering) property is further confirmed valid in both cases. This property allows us to establish a dynamic programming-based algorithm, which solves the problem in O(T ). Finally, numerical tests show differences in optimal plans obtained by both approaches and the influence of varying delays in payment on the WCR of both actors.

关键词： two-level ULS problem lot-sizing working capital requirement ZIO property infinite production capacity

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Performance design of a cryogenic air separation unit for variable working conditions using the lumped

Jinghua XU, Tiantian WANG, Qianyong CHEN, Shuyou ZHANG, Jianrong TAN

《机械工程前沿（英文）》 2020年第15卷第1期页码 24-42 doi: 10.1007/s11465-019-0558-6

摘要： Large-scale cryogenic air separation units (ASUs), which are widely used in global petrochemical and semiconductor industries, are being developed with high operating elasticity under variable working conditions. Different from discrete processes in traditional machinery manufacturing, the ASU process is continuous and involves the compression, adsorption, cooling, condensation, liquefaction, evaporation, and distillation of multiple streams. This feature indicates that thousands of technical parameters in adsorption, heat transfer, and distillation processes are correlated and merged into a large-scale complex system. A lumped parameter model (LPM) of ASU is proposed by lumping the main factors together and simplifying the secondary ones to achieve accurate and fast performance design. On the basis of material and energy conservation laws, the piecewise-lumped parameters are extracted under variable working conditions by using LPM. Takagi–Sugeno (T–S) fuzzy interval detection is recursively utilized to determine whether the critical point is detected or not by using different thresholds. Compared with the traditional method, LPM is particularly suitable for “rough first then precise” modeling by expanding the feasible domain using fuzzy intervals. With LPM, the performance of the air compressor, molecular sieve adsorber, turbo expander, main plate-fin heat exchangers, and packing column of a 100000 Nm O /h large-scale ASU is enhanced to adapt to variable working conditions. The designed value of net power consumption per unit of oxygen production (kW/(Nm O )) is reduced by 6.45%.

关键词： performance design air separation unit (ASU) lumped parameter model (LPM) variable working conditions T–S fuzzy interval detection

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积极开展规划咨询业务，为首都城市建设提供服务——北京市首都规划设计工程咨询开发公司

《中国工程科学》 2000年第2卷第5期页码 91-91

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High-end equipment customer requirement analysis based on opinion extraction

Yuejin TAN, Yuren WANG, Xin LU, Mengsi CAI, Bingfeng GE

《工程管理前沿（英文）》 2018年第5卷第4期页码 479-486 doi: 10.15302/J-FEM-2018035

摘要： Acquisition and analysis of customer requirements are the essential steps in high-end equipment design. Considering that Internet and big data technologies are integrated into the manufacturing industry, we propose a method of analyzing customer requirements based on open-source data. First, online data are collected with focused crawlers and preprocessed to filter noise and duplicate. Then, user opinions are extracted based on the defined template, and users’ sentiments are analyzed. Based on the relationship between user sentiments and attribute parameters, the parameter range that satisfies customers can be obtained. The proposed method is evaluated by using an example of new energy vehicle to verify its availability and feasibility.

关键词： requirement analysis opinion extraction high-end equipment new energy vehicle

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Limit of axial force ratio and requirement for stirrups of RC columns with special shape

WANG Yiqun, XU Yidong, ZHAO Yanjing, CHEN Yunxia

《结构与土木工程前沿（英文）》 2007年第1卷第2期页码 176-181 doi: 10.1007/s11709-007-0019-x

摘要： Thousands of columns with special shape are analyzed by nonlinear numerical methods. The ductility is calculated to investigate the limit of the axial force ratio and circumstantial requirement for stirrups of an reinforced concrete (RC) column with special shape, in the point of view of the characteristic value for providing stirrup. The limit of the axial force ratio of columns with special shape in relation to the characteristic value of the stirrup is obtained. Then, the effect of stirrup arrangement on the ductility of the RC column is discussed in case of buckling of the longitudinal reinforcement and constraint concrete columns. The complete requirement for stirrups of RC column with special shape is given.

关键词： reinforced concrete circumstantial requirement buckling stirrup longitudinal reinforcement

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创新风险与我国风险投资管理

卢锐,盛昭瀚

《中国工程科学》 2002年第4卷第12期页码 86-90

摘要：

由于市场不确定性的影响，风险投资管理迅速兴起，尤其在美国兴起并在全球发展。我国自20世纪80年代开始发展风险投资，对我国工程技术的发展起到很大作用，但也出现了一些的问题。

关键词：创新风险风险投资

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A method to calculate working capacity space of multi-DOF manipulator and the application in excavating

Baochen WEI, Feng GAO

《机械工程前沿（英文）》 2012年第7卷第2期页码 109-119 doi: 10.1007/s11465-012-0323-6

摘要：

Working capacity refers to the velocity output and force output of a manipulator. It is usually be represented by output capacity space. In this paper, the method of Linear Programming and a geometric method are proposed to calculate working capacity spaces in different situations. With the consideration of gravity effect of every component, the output force capacity space of heavy duty manipulators is calculated. The results show that the effect of the gravity is a translation of the capacity space. This paper gives a method for the output capacity express especially for heavy duty manipulators. The output capacity space can be helpful to the driving parameters selection. With the consideration of the gravity effect of every component and the friction at the joints, the excavating force capacity space of the heavy-load excavating mechanism is calculated and is represented as a multi-dimensional polytope. The results show that the effect of the gravity and friction is to translational act on the capacity space.

关键词： working capacity multi-DOF manipulator capacity polytope excavating mechanism

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大型水电项目融资与资本运作——三峡工程10年来的融资策略及实践

李永安

《中国工程科学》 2003年第5卷第10期页码 1-7

摘要：

通过对三峡工程建设10年来的融资策略及实践的总结，深入分析了大型水电项目的融资及资本运作的基本特点，详细论述了在大型水电项目建设管理中如何优化融资结构、降低融资成本、构建持续融资和资本运作载体方式等。

关键词：水电项目融资资本运作

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Unit commitment using dynamic programming–an exhaustive working of both classical and stochastic approach

Balasubramaniyan SARAVANAN, Surbhi SIKRI, K. S. SWARUP, D. P. KOTHARI

《能源前沿（英文）》 2013年第7卷第3期页码 333-341 doi: 10.1007/s11708-013-0259-5

摘要： In the present electricity market, where renewable energy power plants have been included in the power systems, there is a lot of unpredictability in the demand and generation. There are many conventional and evolutionary programming techniques used for solving the unit commitment (UC) problem. Dynamic programming (DP) is a conventional algorithm used to solve the deterministic problem. In this paper DP is used to solve the stochastic model of UC problem. The stochastic modeling for load and generation side has been formulated using an approximate state decision approach. The programs were developed in a MATLAB environment and were extensively tested for a four-unit eight-hour system. The results obtained from these techniques were validated with the available literature and outcome was good. The commitment is in such a way that the total cost is minimal. The novelty of this paper lies in the fact that DP is used for solving the stochastic UC problem.

关键词： unit commitment (UC) deterministic stochastic dynamic programming (DP) optimization state diagram

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中国矿产资源风险勘查资本市场的建设研究

李颖,王安建,李天骄

《中国工程科学》 2019年第21卷第1期页码 74-82 doi: 10.15302/J-SSCAE-2019.01.011

摘要：

本文通过研究国内外风险勘查资本市场的发展现状，结合中国风险勘查市场的实际情况，认为风险勘查资本市场参与主体的缺失、矿业投资诚信的缺失、矿业政策制度的落后、矿业资本市场配套制度不健全等问题是构建风险勘查资本市场面临的主要挑战，并提出了利用境外市场培育中国风险勘查市场参与主体、改善国内矿业投资环境并建立信用体系，最终建立中国风险勘查资本市场板块的“三步式”发展路径。

关键词：矿产资源风险勘查资本市场投资环境

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Exergy analysis of R1234ze(Z) as high temperature heat pump working fluid with multi-stage compression

Bin HU, Di WU, L.W. WANG, R.Z. WANG

《能源前沿（英文）》 2017年第11卷第4期页码 493-502 doi: 10.1007/s11708-017-0510-6

摘要： In this paper, the simulation approach and exergy analysis of multi-stage compression high temperature heat pump (HTHP) systems with R1234ze(Z) working fluid are conducted. Both the single-stage and multi-stage compression cycles are analyzed to compare the system performance with 120°C pressurized hot water supply based upon waste heat recovery. The exergy destruction ratios of each component for different stage compression systems are compared. The results show that the exergy loss ratios of the compressor are bigger than that of the evaporator and the condenser for the single-stage compression system. The multi-stage compression system has better energy and exergy efficiencies with the increase of compression stage number. Compared with the single-stage compression system, the coefficient of performance (COP) improvements of the two-stage and three-stage compression system are 9.1% and 14.6%, respectively. When the waste heat source temperature is 60°C, the exergy efficiencies increase about 6.9% and 11.8% for the two-stage and three-stage compression system respectively.

关键词： multi-stage compression high temperature heat pump heat recovery exergy destruction R1234ze(Z) working fluid

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Cream coated on endotracheal tube with or without epidural lidocaine reduces isoflurane requirement during

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《医学前沿（英文）》 2012年第6卷第3期页码 302-306 doi: 10.1007/s11684-012-0194-6

摘要：

This study was designed to evaluate the effect of tracheal topical anesthesia using EMLA^? Cream (EC) coated on the endotracheal tube (ETT) with or without epidural anesthesia (EA) on isoflurane requirement during general anesthesia (GA) and investigate whether EC coated on the ETT with EA was associated with the additive effect compared with the effect when each anesthetic was administered independently. The prospective randomized, double-blinded, and controlled study included 60 ASA I–II patients scheduled for upper abdominal surgery requiring GA. Patients were randomly assigned to one of the following groups: group 1 received GA, group 2 received EC+ GA, group 3 received GA+ EA, and group 4 received EC+ GA+ EA. Isoflurane was administered at the required concentrations to maintain the mean arterial pressure at a level not exceeding 20% of preoperative values. The percentage mean expired concentration (%MEC) was used in calculating the isoflurane requirement. Emergence agitation, postoperative sore throat, and hoarseness were recorded. Groups 2, 3, and 4 exhibited a significant reduction on isoflurane requirement compared with group 1 (P<0.05). The isoflurane requirement evaluated by %MEC decreased by 12%, 38%, and 50% in groups 2, 3, and 4, respectively. The incidence of emergence agitation was significantly lower in groups 2 and 4 than those in groups 1 and 3 (P<0.05). Tracheal topical anesthesia using EC coated on ETT with or without EA reduced the isoflurane requirement during GA, indicating that EC combined with EA exhibited an additive effect on the requirement of general anesthetic.

关键词： EMLA? Cream epidural anesthesia general anesthesia isoflurane lidocaine

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Working Up Green, and Living Up Green

Ji-shan He

《工程管理前沿（英文）》 2014年第1卷第1期页码 2-2 doi: 10.15302/J-FEM-2014002

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Experimental study on working parameters of earth pressure balance shield machine tunneling in soft ground

ZHU Hehua, LIAO Shaoming, XU Qianwei, ZHENG Qizhen

《结构与土木工程前沿（英文）》 2008年第2卷第4期页码 350-358 doi: 10.1007/s11709-008-0051-5

摘要： Deep sedimentary deposits of soft clays are widely distributed in coastal areas as well as many interior major cities in China. In order to study the stratum adaptability of earth pressure balance (EPB) shield machine tunneling in such types of soft ground, model tests of tunneling excavation, using the running tunnel of the Shanghai Metro Line M8 as a background, are carried out with different over burden ratios, opening rates of cutter head, driving speeds and rotation speeds of screw conveyor. Based on the test results, the interrelationships between chamber pressure and mucking efficiency, mucking rate and driving speed, thrust force and torque are obtained. The influences of tunnel depth, opening rate of cutter head and driving speed on thrust force and torque are revealed. Such findings can not only facilitate establishing relationships between shield working parameters and soil properties, but also serve as a guide for the design and construction of shield tunnel in soft ground.

关键词： construction different coastal conveyor excavation

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Performance of a bi-layer solar steam generation system working at a high-temperature of top surface

Jinxin ZHONG, Congliang HUANG

《能源前沿（英文）》 2023年第17卷第1期页码 141-148 doi: 10.1007/s11708-021-0725-4

摘要： Many efforts have been focused on enhancing the vapor generation in bi-layer solar steam generation systems for obtaining as much pure water as possible. However, the methods to enhance the vapor temperature is seldom studied although the high-temperature vapor has a wide use in medical sterilization and electricity generation. In this work, to probe the high-temperature vapor system, an improved macroscopic heat and mass transfer model was proposed. Then, using the finite element method to solve the model, the influences of some main factors on the evaporation efficiency and vapor temperature were discussed, including effects of the vapor transport conditions and the heat dissipation conditions. The results show that the high-temperature vapor could not be obtained by enhancing the heat-insulating property of the bi-layer systems but by applying the optimal porosity and proper absorbers. This paper is expected to provide some information for designing a bi-layered system to produce high-temperature vapor.

关键词： solar steam generation solar energy numerical method porous material