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p.r.ormance of seven highway construction contracting methods analyzed by project size

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Frontiers of engineering management 2018年第2期5卷 240-250页

作者： Yuanxin ZHANG Abdol CHINI r.Edward MINCHIN Jr. Lourdes pTSCHELINZEW Dev SHAH School of management Guangzhou UniversityGuangzhou 510006China rinker School of Construction management University of FloridaGainesvilleFL 32611USA

The conventional Design-Bid-Build(DBB)construction contracting method has had various drawbacks exposed in highway construction practice, including lack of communication, inefficient design, antagonizing relationships, and increased disputes. To mitigate the negative aspects of DBB, several alternative contracting methods and alternative project delivery systems have been devised and introduced to the industry over the past30 years. Five such innovations were tested by a research team from the University of Florida under the sponsorship of the Florida department of Transp.r.ation(FDOT). To p.r.orm a realistic assessment, this study categorized FDOT projects built between 2006 and 2015 into groups according to current contract amounts. Both absolute and relative metrics were defined and employed. For comp.r.son p.r.oses, a collective analysis on all gathered data was p.r.ormed. Additionally, the influence of outliers on the results was examined. The results showed that analyses based on individual cost categories are more convincing because large projects tend to impose stronger influence on the analyses. In addition, outliers must be identified and screened to reach realistic and reliable conclusions. With regard to the actual p.r.ormance of the contracting methods, each p.r.orms differently within different cost categories.

关键词： alternative contracting methods time cost,p.r.ormance evaluation

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上缓下陡土质高边坡关键块体的破坏模式研究

水利与建筑工程学报 2018年第3期16卷 165-169页

作者：汪儒鸿周海清刘琪颖陆军勤务学院军事设施系重庆401331 岩土力学与地质环境保护重庆市重点实验室重庆401331

针对部分高边坡坡度变化大,在采取锚索格构类的大范围支挡时存在工程成本高昂,对环境影响较大的问题,在保证安全的前提下,为尽可能的节省该类高边坡的治理成本,缩减施工规模,专门提出针对上缓下陡地形土质高边坡的"关键块体"概念。通过... 详细信息

针对部分高边坡坡度变化大,在采取锚索格构类的大范围支挡时存在工程成本高昂,对环境影响较大的问题,在保证安全的前提下,为尽可能的节省该类高边坡的治理成本,缩减施工规模,专门提出针对上缓下陡地形土质高边坡的"关键块体"概念。通过对"关键块体"稳定性及破坏模式的分析,可以为符合条件的高边坡提供局部支挡设计的理论依据。与传统的边坡稳定分析方法相比,"关键块体"分析方法针对性更强,更适合对特殊地形土质高边坡的支挡设计中引为参考。从施工角度来说,该方法为土体临空面较高而难以治理的高边坡提供了新的支挡设计思路,实际应用价值较大。

关键词：关键块体上缓下陡地形土质高边坡局部支挡稳定分析

An Optical Method for Assessing Scratch Damage in Bulk Materials and Coatings

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An Optical Method for Assessing Scratch Damage in Bulk Mater...

He-enhanced heterogeneity of radiation-induced segregation in FeNiCoCr high-entropy alloy

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作者： I.M.Hutchings p.Z.Wang G.C.p.r.y Institute for manufacturing University of CambridgeMill LaneCambridge CB2 1RXUK department of Materials Science and Metallurgy University of CambridgePembroke StreetCambridge CB2 3QZUK department of Materials Science and Metallurgy University of CambridgePembroke StreetCambridge CB2 3QZUK

＜正＞ For some applications,the most imp.r.ant prop.r.y of a scratch in a surface or coating is the visual p.r.eption of that scratch by a human observer.A method is proposed to predict the visual impact of scratch damage from measurements of geometrical dimensions and changes in greylevel.A "logarithmic instrumental visibility",Vi is defined by Vi=log ΔG25dA and is shown to correlate well with visibility,as p.r.eived by human observers,for a wide range of simulated scratch images and also for real scratches in filled polyolefin sheets.

关键词： scratch testing surface damage

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Journal of Materials Science & Technology 2022年第6期101卷 226-233页

作者： W.T.Lin G.M.Yeli G.Wang J.H.Lin S.J.Zhao D.Chen S.F.Liu F.L.Meng Y.r.Li F.He Y.Lu J.J.Kai department of Mechanical engineering City University of Hong KongHong KongChina Institute of Nuclear&New Energy Technology Tsinghua UniversityBeijingChina department of physics Southern University of Science and TechnologyShenzhenChina Centre for Advanced Nuclear Safety and Sustainable Development City University of Hong KongHong KongChina School of Environmental Science and engineering Southern University of Science and TechnologyShenzhenChina School of Materials Science and engineering Shanghai UniversityShanghaiChina Nano-manufacturing Laboratory(NML) City University of Hong Kong Shenzhen Research InstituteShenzhenChina

radiation-induced segregation(rIS) is a typical non-equilibrium process that can dramatically alter the behavior of defect sinks and material prop.r.ies under irradiation. However, rIS mechanisms have been rarely studied around small He bubbles owing to the technical challenges involved in direct measurements of local chemistry. Here, using state-of-the-art atom probe tomography, we rep.r. the rIS behavior near He bubbles in the Fe Ni Co Cr high-entropy alloy that indicates Co segregates most strongly, followed by weaker Ni segregation, whereas Fe and Cr are depleted almost to the same degree. Exceptionally, the magnitude of Co segregation around He bubbles is higher than previously measured values at voids and dislocation loops. Electron energy-loss spectroscopy was used to measure the He density and pressure inside individual bubbles. We demonstrate that He bubbles are over-pressurized at the irradiation temp.r.ture that could result in the vacancy bias and the subsequent vacancy-dominated rIS ***-principles calculations further reveal that there are repulsive interactions between He and Co atoms that may reduce the frequency of Co-vacancy exchange. As a result, He atoms likely retard Co diffusion via the vacancy mechanism and enhance the heterogeneity of rIS in Co-containing multicomponent alloys. These insights could provide the basis for understanding He effects in nuclear materials and open an avenue for tailoring the local chemical order of medium-and high-entropy alloys.

关键词： High-entropy alloy radiation-induced segregation He bubbles Atom probe tomography Electron energy-loss spectroscopy

Effect of fly ash filler size on mechanical prop.r.ies of polymer matrix composites

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Effect of fly ash filler size on mechanical properties of po...

基于分流特性的H型截面长轴类锻件毛坯精确设计方法

作者： r.Satheesh raja K.Manisekar V.Manikandan department of Mechanical engineering PET Engineering College Centre for manufacturing Sciences National Engineering College department of Mechanical engineering SVCET

In this work, fly ash has been used as filler material in epoxy polymer to produce p.r.iculate reinforced polymer composites. The chemical composition of fly ash and its p.r.icle size plays an imp.r.ant role in the enhancement of physical and mechanical prop.r.ies of polymer matrix composites （pMC）. Here four different sizes of fly ash （50 μm, 480 nm, 350 nm, 300 nm） with 10 wt % are impregnated with epoxy resin to process the pMC by using simple mold arrangement. The size reduction is obtained by means of ball milling technique. Scanning electron microscope （SEM） and energy disp.r.ive spectroscopy （EDS） are used to characterize the fly ash. Mechanical prop.r.ies such as hardness and impact strength are analyzed as p.r.ASTM standards. It was found that size reduction of fly ash p.r.icle enhanced the strength of pMC.

关键词： Epoxy Fly ash filler material Mechanical prop.r.ies pMC

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塑性工程学报 2018年第5期25卷 39-45页

作者：邓磊任治华王新云金俊松夏巨谌刘世宝付成林华中科技大学材料成形与模具技术国家重点实验室湖北武汉430074 江苏界达特异新材料股份有限公司江苏江阴214443 中国第一汽车集团有限公司发展制造部吉林长春130011

分析了长轴锻件H型截面在锻造过程中的材料分流规律,发现由于分流线两侧接触边界条件的变化,分流线两侧面积比的变化可分为5个阶段。基于主应力法分析建立了不同接触边界条件下的分向流动计算模型,可根据H型截面两侧的充填状态计算确定... 详细信息

分析了长轴锻件H型截面在锻造过程中的材料分流规律,发现由于分流线两侧接触边界条件的变化,分流线两侧面积比的变化可分为5个阶段。基于主应力法分析建立了不同接触边界条件下的分向流动计算模型,可根据H型截面两侧的充填状态计算确定分流线的位置。进一步根据分流规律建立了分流填充模型,能够计算出不同分流状态下的分流线两侧体积分配量。基于上述模型,通过迭代调整毛坯中心位置和求解H型截面两侧型腔充填情况,逐步优化出最佳的毛坯中心位置,可达到两侧筋部同时充满的效果,并提高材料利用率。以某型号控制臂锻件为具体对象,验证了新方法的准确性。

关键词：锻造长轴类锻件分流主应力法建模 H型截面

p.r.ormance Improvement in manufacturing Shop Floor Op.r.tions of Developing Countries Based on Three Characteristics of Information Flow

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Journal of Computer and Communications 2022年第3期10卷 46-65页

作者： Joseph Voufo André Marie Mbakop Florent Biyeme rolland Djomi pélagie Flore Nanfack Temgoua Jean raymond Lucien Meva’a National Advanced School of engineering of Yaoundé (NASEY) Yaoundé Cameroon Laboratory of Civil and Mechanical engineering Yaoundé Cameroon department of Mechanical and Industrial engineering Yaoundé Cameroon Ministry of Scientific research and Innovation National Committee for Development of Technologies Yaoundé Cameroon

The management of information flow for production improvement has always been a target in the research. In this pap.r. the focus is on the analysis model of the characteristics of information flow in shop floor op.r.tions based on the influence that dimension (supp.r. or medium), direction and the quality information flow have on the value of information flow using machine learning classification algorithms. The obtained results of classification algorithms used to analyze the value of information flow are Decision Trees (DT) and random Forest (rF) with a score of 0.99% and the mean absolute error of 0.005. The results also show that the management of information flow using DT or rF shows that, the dimension of information such as digital information has the greatest value of information flow in shop floor op.r.tions when the shop floor is totally digitalized. Direction of information flow does not have any great influence on shop floor op.r.tions processes when the op.r.tions processes are digitalized or done by op.r.tors as machines.

关键词： Developing Countries Information Flow Characteristics Machine Learning Shop Floor Op.r.tions Value of Information Flow

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应用于准时制的MpS/Mrp模型

系统工程理论方法应用 2001年第4期10卷 302-306页

作者：肖依永王树明张人千北京航空航天大学经济管理学院北京100083

根据制造企业准时生产 (Just In Time,JIT)理论的生产管理需求 ,通过一种面向准时生产的、含生产滞后期的缩进嵌套 BOM档将主生产计划 (MpS)和零件订购计划 (Mrp)紧密结合起来 ,建立了基于JIT的两者的数学模型 ,实现从产品需求、产品生... 详细信息

根据制造企业准时生产 (Just In Time,JIT)理论的生产管理需求 ,通过一种面向准时生产的、含生产滞后期的缩进嵌套 BOM档将主生产计划 (MpS)和零件订购计划 (Mrp)紧密结合起来 ,建立了基于JIT的两者的数学模型 ,实现从产品需求、产品生产、零件装配、零件请购到零件到货的准时计算 ,避免了传统的基于 JIT的 MpS或 Mrp的单独讨论。运用该模型可以实现在满足生产需求和经济订货批量的条件下。

关键词：主生产计划数学模型物料清单制造企业管理 MpS Mrp 零件订购计划企业准进生产理论

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探讨二级医院医疗设备管理问题及改进对策

医疗卫生装备 2018年第7期39卷 80-83页

作者：丁静蔡军杰张华郭乾坤解放军285医院药械科河北邯郸056001 解放军285医院门诊部河北邯郸056001 解放军285医院医务处河北邯郸056001

目的:探讨二级医院医疗设备管理存在的问题,提出有效保障医疗设备使用及管理的改进措施。方法:通过分析二级医院医疗设备管理各级参与者及工作内容等方面存在的问题,提出落实管理制度、实施人才建设、加强沟通协作等改进措施。结果:二... 详细信息

目的:探讨二级医院医疗设备管理存在的问题,提出有效保障医疗设备使用及管理的改进措施。方法:通过分析二级医院医疗设备管理各级参与者及工作内容等方面存在的问题,提出落实管理制度、实施人才建设、加强沟通协作等改进措施。结果:二级医院医疗设备管理各级参与者进一步提高了思想认识,并制订了相应对策,确保了医疗设备安全使用。结论:不断提高医疗设备管理水平,对提高医疗设备使用效率、保证医院正常发展至关重要。

关键词：二级医院医疗设备管理医学工程技术人员对策