期刊文献+
共找到1,108篇文章
< 1 2 56 >
每页显示 20 50 100
A Comprehensive Overview of the ELECTRE Method in Multi-Criteria Decision-Making 被引量:1
1
作者 Hamed Taherdoost Mitra Madanchian 《Journal of Management Science & Engineering Research》 2023年第2期5-16,共12页
The ELECTRE(ELimination Et Choix Traduisant la REalite)method has gained widespread recognition as one of the most effective multi-criteria decision-making(MCDM)methods.Its versatility allows it to be applied in a wid... The ELECTRE(ELimination Et Choix Traduisant la REalite)method has gained widespread recognition as one of the most effective multi-criteria decision-making(MCDM)methods.Its versatility allows it to be applied in a wide range of areas such as engineering,economics,business,environmental management and many others.This paper aims to provide an overview of the ELECTRE method,including its fundamental concepts,applications,advantages,and limitations.At its core,the ELECTRE method is an outranking family of MCDM techniques,which allows for the direct comparison of alternatives based on a set of criteria.The method takes into account the preferences and importance of decision-makers and generates a ranking of the alternatives based on their relative strengths and weaknesses.The ELECTRE method is a powerful tool for decision-making,and its applicability to a wide range of fields demonstrates its versatility and adaptability.By understanding its concepts,applications,merits,and demerits,decision-makers can use the ELECTRE method to make informed and effective decisions in a variety of contexts. 展开更多
关键词 Decision making Multi criteria decision making ELECTRE method ELimination Et Choix Traduisant la REalite method Multi attribute decision making
下载PDF
Coal-rock gas:Concept,connotation and classification criteria
2
作者 LI Guoxin ZHANG Shuichang +11 位作者 HE Haiqing HE Xinxing ZHAO Zhe NIU Xiaobing XIONG Xianyue ZHAO Qun GUO Xujie HOU Yuting ZHANG Lei LIANG Kun DUAN Xiaowen ZHAO Zhenyu 《Petroleum Exploration and Development》 SCIE 2024年第4期897-911,共15页
In recent years,great breakthroughs have been made in the exploration and development of natural gas in deep coal-rock reservoirs in Junggar,Ordos and other basins in China.In view of the inconsistency between the ind... In recent years,great breakthroughs have been made in the exploration and development of natural gas in deep coal-rock reservoirs in Junggar,Ordos and other basins in China.In view of the inconsistency between the industrial and academic circles on this new type of unconventional natural gas,this paper defines the concept of"coal-rock gas"on the basis of previous studies,and systematically analyzes its characteristics of occurrence state,transport and storage form,differential accumulation,and development law.Coal-rock gas,geologically unlike coalbed methane in the traditional sense,occurs in both free and adsorbed states,with free state in abundance.It is generated and stored in the same set of rocks through short distance migration,occasionally with the accumulation from other sources.Moreover,coal rock develops cleat fractures,and the free gas accumulates differentially.The coal-rock gas reservoirs deeper than 2000 m are high in pressure,temperature,gas content,gas saturation,and free-gas content.In terms of development,similar to shale gas and tight gas,coal-rock gas can be exploited by natural formation energy after the reservoirs connectivity is improved artificially,that is,the adsorbed gas is desorbed due to pressure drop after the high-potential free gas is recovered,so that the free gas and adsorbed gas are produced in succession for a long term without water drainage for pressure drop.According to buried depth,coal rank,pressure coefficient,reserves scale,reserves abundance and gas well production,the classification criteria and reserves/resources estimation method of coal-rock gas are presented.It is preliminarily estimated that the coal-rock gas in place deeper than 2000 m in China exceeds 30×10^(12)m^(3),indicating an important strategic resource for the country.The Ordos,Sichuan,Junggar and Bohai Bay basins are favorable areas for large-scale enrichment of coal-rock gas.The paper summarizes the technical and management challenges and points out the research directions,laying a foundation for the management,exploration,and development of coal-rock gas in China. 展开更多
关键词 coal-rock gas coalbed methane adsorbed gas free gas classification criteria reserves estimation method
下载PDF
MULTI-PARAMETER ACCELERATED MODIFIED NEWTON-RAPHSON METHODS FOR RIGIDPLASTIC FE ANALYSIS
3
作者 Shi Gang Liu Xiaolin 《Acta Mechanica Solida Sinica》 SCIE EI 2002年第4期323-331,共9页
Applications of certain multi-parameter acceleration techniques used with themodified New-ton-Raphson (mN-R) methods to solve the nonlinear equations arising from rigid-plasticfinite element analysis are investigated.... Applications of certain multi-parameter acceleration techniques used with themodified New-ton-Raphson (mN-R) methods to solve the nonlinear equations arising from rigid-plasticfinite element analysis are investigated. New modified multi-parameter techniques, developed fromCrisfield's multi-parameter methods, are utilized to solve these nonlinear equations. The numericalperformance of these techniques is compared with the standard Newton-Raphson method (sN-R),Crisfield's single parameter method (C1), Crisfield's two parameter method (C2) and Crisfield'sthree parameter method (C3). The new techniques do not involve additional residual force calculationand require little extra computational effort. In addition, they are more robust and efficient thanother existing acceleration techniques. 展开更多
关键词 rigid-plastic FEM standard newton-raphson method modified newton-raphsonmethod crisfield's multi-parameter accelerated techniques modified multi-parameter acceleratedtechniques
下载PDF
Chaos control of gear system with elastomeric web based on multi-parameter multi-step method
4
作者 刘海霞 江波 +1 位作者 王三民 郭家舜 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2012年第5期23-30,共8页
This paper employs a multi-parameter multi-step chaos control method, which is built up on the OGY method, to stabilize desirable UPOs of a gear system with elastomeric web as a high-dimensional and non-hyperbolic cha... This paper employs a multi-parameter multi-step chaos control method, which is built up on the OGY method, to stabilize desirable UPOs of a gear system with elastomeric web as a high-dimensional and non-hyperbolic chaotic system, and the analyses are carried out. Three types of relations between components of a certain control parameter combination are defined in a certain control process. Special emphasis is put on the comparison of control efficiencies of the multi-parameter multi-step method and single-parameter multi-step method. The numerical experiments show the ability to switch between different orbits and the method can be a good chaos control alternative since it provides a more effective UPOs stabilization of high-dimensional and non-hyperbolic chaotic systems than the single-parameter chaos control, and according to the relation between components of each parameter combination, the best combination for chaos control in a certain UPO stabilization process are obtained. 展开更多
关键词 chaos control a gear system with elastomeric web multi-parameter multi-step method high-dimensional and non-hyperbolic system
下载PDF
Initial support distance of a non-circular tunnel based on convergence constraint method and integral failure criteria of rock 被引量:6
5
作者 AN Xue-xu HU Zhi-ping +3 位作者 SU Yan CAO Shuang-li TAO Lei ZHANG Yong-hui 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第11期3732-3744,共13页
For deep tunnel projects,selecting an appropriate initial support distance is critical to improving the self-supporting capacity of surrounding rock.In this work,an intuitive method for determining the tunnel’s initi... For deep tunnel projects,selecting an appropriate initial support distance is critical to improving the self-supporting capacity of surrounding rock.In this work,an intuitive method for determining the tunnel’s initial support distance was proposed.First,based on the convergence-confinement method,a three-dimensional analytical model was constructed by combining an analytical solution of a non-circular tunnel with the Tecplot software.Then,according to the integral failure criteria of rock,the failure tendency coefficients of hard surrounding rock were computed and the spatial distribution plots of that were constructed.On this basis,the tunnel’s key failure positions were identified,and the relationship between the failure tendency coefficient at key failure positions and their distances from the working face was established.Finally,the distance from the working face that corresponds to the critical failure tendency coefficient was taken as the optimal support distance.A practical project was used as an example,and a reasonable initial support distance was successfully determined by applying the developed method.Moreover,it is found that the stability of hard surrounding rock decreases rapidly within the range of 1.0D(D is the tunnel diameter)from the working face,and tends to be stable outside the range of 1.0D. 展开更多
关键词 tunnel engineering convergence confinement method integral failure criteria of rock non-circular tunnel initial supporting distance
下载PDF
Brief Analysis,Method and Criteria of Technical Translation
6
作者 周蕾 《海外英语》 2012年第21期153-154,共2页
In this essay,I will analyse the characteristics of technical texts,the methods for translation based on the former stage of research,criteria for a better translation,and critiques in between.Also,the essay will expl... In this essay,I will analyse the characteristics of technical texts,the methods for translation based on the former stage of research,criteria for a better translation,and critiques in between.Also,the essay will explore the limitations of Peter Newmark's theory of technical translation and the whole aspect of translation. 展开更多
关键词 TECHNICAL TRANSLATION ANALYSIS method criteria Pet
下载PDF
A multi-criteria decision-making approach for comparing sample preservation and DNA extraction methods from swine feces 被引量:2
7
作者 Sepideh Pakpour Abbas S. Milani Martin R. Chénier 《American Journal of Molecular Biology》 2012年第2期159-169,共11页
Molecular microbiological methods, such as competetive PCR, real-time PCR, denaturing gradient gel electrophoresis (DGGE) and large-scale parallel-pyrosequencing, require the extraction of sufficient quantity of high ... Molecular microbiological methods, such as competetive PCR, real-time PCR, denaturing gradient gel electrophoresis (DGGE) and large-scale parallel-pyrosequencing, require the extraction of sufficient quantity of high quality DNA from microbiologically and chemically complex matrices. Due to difficulties in the field to standardize/select the optimum DNA preservation-extraction methods in view of laboratories differences, this article attempts to present a straight-forward mathematical framework for comparing some of the most commonly used methods. To this end, as a case study, the problem of selecting an optimum sample preservation-DNA extraction strategy for obtaining total bacterial DNA from swine feces was considered. Two sample preservation methods (liquid nitrogen and RNAlater?) and seven extraction techniques were paired and compared under six quantitative DNA analysis criteria: yield of extraction, purity of extracted DNA (A260/280 and A 260/230 ratios), duration of extraction, degradation degree of DNA, and cost. From a practical point of view, it is unlikely that a single sample preservation-DNA extraction strategy can be optimum for all selected criteria. Hence, a systematic multi-criteria decision-making (MCDM) approach was used to compare the methods. As a result, the ZR Fecal DNA MiniPrepTM DNA extraction kit for samples preserved either with liquid nitrogen or RNAlater? were identified as potential optimum solutions for obtaining total bacterial DNA from swine feces. Considering the need for practicality for in situ applications, we would recommend liquid nitrogen as sample preservation method, along with the ZR Fecal DNA MiniPrepTM kit. Total bacterial DNA obtained by this strategy can be suitable for downstream PCR-based DNA analyses of swine feces. 展开更多
关键词 SAMPLE PRESERVATION DNA Extraction SWINE FECES MULTI-criteria Decision-Making Weighed SUM method
下载PDF
Dynamic programming methodology for multi-criteria group decision-making under ordinal preferences 被引量:3
8
作者 Wu Li Guanqi Guo +1 位作者 Chaoyuan Yue Yong Zhao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第6期975-980,共6页
A method of minimizing rankings inconsistency is proposed for a decision-making problem with rankings of alternatives given by multiple decision makers according to multiple criteria. For each criteria, at first, the ... A method of minimizing rankings inconsistency is proposed for a decision-making problem with rankings of alternatives given by multiple decision makers according to multiple criteria. For each criteria, at first, the total inconsistency between the rankings of all alternatives for the group and the ones for every decision maker is defined after the decision maker weights in respect to the criteria are considered. Similarly, the total inconsistency between their final rankings for the group and the ones under every criteria is determined after the criteria weights are taken into account. Then two nonlinear integer programming models minimizing respectively the two total inconsistencies above are developed and then transformed to two dynamic programming models to obtain separately the rankings of all alternatives for the group with respect to each criteria and their final rankings. A supplier selection case illustrated the proposed method, and some discussions on the results verified its effectiveness. This work develops a new measurement of ordinal preferences’ inconsistency in multi-criteria group decision-making (MCGDM) and extends the cook-seiford social selection function to MCGDM considering weights of criteria and decision makers and can obtain unique ranking result. 展开更多
关键词 multi-criteria group decision-making (MCGDM) ordinal preference minimum deviation method dynamic programming Cook-Seiford social selection function.
下载PDF
Multi-Parameter Analysis of Optimal Transitions from Chaotic to Stable Regions for Two Classes of Systems
9
作者 Yury Talagaev Andrey Tarakanov 《Advances in Pure Mathematics》 2013年第1期214-218,共5页
The study of the parameter space of chaotic systems is complicated by its high dimensionality (multi-parametricability). Two approaches to the study of chaotic systems are presented: multi-parameter analysis and optim... The study of the parameter space of chaotic systems is complicated by its high dimensionality (multi-parametricability). Two approaches to the study of chaotic systems are presented: multi-parameter analysis and optimal suppression of chaotic dynamics. For non-autonomous chaotic systems, this is the way to compare the effectiveness of various correction parameters that provide optimal removal of irregular dynamics. For the class of autonomous chaotic systems, this is the way to investigate the optimal conditions of super-stable behavior for the chaotic system. 展开更多
关键词 CHAOTIC SYSTEMS multi-parameter Analysis MELNIKOV method Super-Stability
下载PDF
Landfill Site Selection Using GIS and Multi-Criteria Decision-Making AHP and SAW Methods: A Case Study in Sulaimaniyah Governorate, Iraq
10
作者 Karwan Alkaradaghi Salahalddin S. Ali +1 位作者 Nadhir Al-Ansari Jan Laue 《Engineering(科研)》 2020年第4期254-268,共15页
Lack of land for waste disposal is one of the main problems facing urban areas in developing countries. The Sulaimaniyah Governorate, located in northern Iraq, is one of the main cities of the country in the Kurdistan... Lack of land for waste disposal is one of the main problems facing urban areas in developing countries. The Sulaimaniyah Governorate, located in northern Iraq, is one of the main cities of the country in the Kurdistan Region, covering an area of 2400 km2. Currently, there is no landfill site in the study region that meets scientific and environmental requirements, inappropriate dumping of solid waste causes adverse effects on the environment, economic and urban aesthetic. To overcome with this phenomenon, it is very crucial to suggest a landfill site, even in countries that recycle or burn their waste to protect the environment. Landfill sites should be carefully selected by considering all regulations and other restrictions. The integration of geographic information systems and multi-criteria decision analysis is used in this study to select suitable landfill locations in the region, for this purpose, thirteen layers are prepared according to their importance including urban area, villages, rivers, groundwater depth, slope, elevation, soil types, geological formations, roads, oil and gas field, land use classification, archaeological site and power lines. Two different methods (simple additive weighting and analytic hierarchy process) are implemented in a geographical information system to obtain the suitability index map for candidate landfill sites, where all these sites satisfied the scientific and environmental criteria which were adopted in this study. The comparison of the maps resulting from these two different methods demonstrates that both methods produced consistent results. 展开更多
关键词 LANDFILL Site criteria WEIGHTS GIS Software ANALYTIC Hierarchy Process (AHP) Simple Additive Weighting (SAW) method
下载PDF
A METHOD OF ESTIMATING THE INFLUENCE OF EXPERIMENTAL ERRORS ON THE EXPERIMENTAL RESULTS OF MATERIAL PARAMETERS AND THE CRITERIA TO VALUE THIS INFLUENCE
11
作者 Yao Weixing Tsinghua University 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 1991年第3期320-325,共6页
In this paper the main sources causing the scatter of the experimental results of the material parameters are discussed. They can be divided into two parts: one is the experimental errors which are introduced because ... In this paper the main sources causing the scatter of the experimental results of the material parameters are discussed. They can be divided into two parts: one is the experimental errors which are introduced because of the inaccuracy of experimental equipment, the experimental techniques, etc., and the form of the scatter caused by this source is called external distribution. The other is due to the irregularity and inhomogeneity of the material structure and the randomness of deformation process. The scatter caused by this source is inherent and then this form of the scatter is called internal distribution. Obviously the experimental distribution of material parameters combines these two distributions in some way; therefore, it is a sum distribution of the external distribution and the internal distribution. In view of this , a general method used to analyse the influence of the experimental errors on the experimental results is presented, and three criteria used to value this influence are defined. An example in which the fracture toughness KIC is analysed shows that this method is reasonable, convenient and effective. 展开更多
关键词 A method OF ESTIMATING THE INFLUENCE OF EXPERIMENTAL ERRORS ON THE EXPERIMENTAL RESULTS OF MATERIAL PARAMETERS AND THE criteria TO VALUE THIS INFLUENCE
下载PDF
煤岩气:概念、内涵与分类标准 被引量:4
12
作者 李国欣 张水昌 +11 位作者 何海清 何新兴 赵喆 牛小兵 熊先钺 赵群 郭绪杰 侯雨庭 张雷 梁坤 段晓文 赵振宇 《石油勘探与开发》 EI CAS CSCD 北大核心 2024年第4期783-795,共13页
近年来,准噶尔、鄂尔多斯等盆地深层煤岩储层中的天然气勘探开发取得重大突破。针对目前工业界和学术界对这种新类型非常规天然气表述不一致的现状,在前人研究的基础上定义了“煤岩气”概念,并系统对比剖析其赋存状态、运储形式、差异... 近年来,准噶尔、鄂尔多斯等盆地深层煤岩储层中的天然气勘探开发取得重大突破。针对目前工业界和学术界对这种新类型非常规天然气表述不一致的现状,在前人研究的基础上定义了“煤岩气”概念,并系统对比剖析其赋存状态、运储形式、差异聚集和开发规律。在地质上,煤岩气不同于传统意义上的煤层气,具有游离气与吸附气并存、富含游离气,自生自储-微距运移并可有他源的聚集,煤岩割理裂缝发育、游离气差异富集等特点,埋深超过2000m的深层煤岩气具有“高压力、高温度、高含气、高饱和、高游离”的“5高”地质特征;在开发上,与页岩气、致密气特征相似,人工改善储层连通性后,无需排水降压,高势能游离气弹性驱动产出、压降后吸附气解吸接替,可依靠地层自然能量开采,游离气与吸附气连续接力长周期产气。按照埋深、煤阶、压力系数、储量规模、储量丰度和气井产量等,提出了煤岩气的分类标准和资源/储量估算方法。初步估算埋深超过2 000 m的中国煤岩气地质资源量超过30×1012m3,是国家重要的战略资源。提出鄂尔多斯、四川、准噶尔和渤海湾等盆地是煤岩气的规模富集有利区,梳理了技术与管理挑战并指出攻关方向,为中国煤岩气管理与勘探开发奠定理论、评价和生产实践基础。 展开更多
关键词 煤岩气 煤层气 吸附气 游离气 分类标准 储量估算方法
下载PDF
An Evolutionary Algorithm Coupled to an Outranking Method for the Multicriteria Shortest Paths Problem
13
作者 Frédéric Guidana Gazawa   +1 位作者 Kolyang Irépran Damakoa 《American Journal of Operations Research》 2019年第3期114-128,共15页
In this article, we are interested in solving a combinatorial optimization problem, the shortest path problem in a multi-attribute graph, by the out-ranking methods. A multi-attribute graph has simultaneously qualitat... In this article, we are interested in solving a combinatorial optimization problem, the shortest path problem in a multi-attribute graph, by the out-ranking methods. A multi-attribute graph has simultaneously qualitative and quantitative criteria. This situation gives rise to incomparable paths thus forming the Pareto front. Outranking methods in Multi-criteria Decision Making (MCDM) are the only methods that can take into account this situation (incomparability of actions). After presenting the categories of Multi-criteria Decision Making (MCDM) and the difficulties related to the problems of the shortest paths, we propose an evolutionary algorithm based on the outranking methods to solve the problem of finding “best” paths in a multi-attribute graph with non-additive criteria. Our approach is based on the exploration of induced subgraphs of the outranking graph. Properties have been established to serve as algorithmic basis. Numerical experiments have been carried out and the results presented in this article. 展开更多
关键词 MULTI-criteria DECISION Making EVOLUTIONARY Algorithm Shortest Path Outranking method Induced SUBGRAPHS
下载PDF
Study of A Multi-criteria Evaluation Methodology for Nuclear Fuel Cycle System Based on Sustainability
14
作者 Hidekazu Yoshikawa 《工程科学(英文版)》 2006年第1期33-39,共7页
This paper presents a multi-criteria evaluation methodology for nuclear fuel cycle options in terms of energy sustainability. Starting from the general sustainability concept and the public acceptance questionnaire, a... This paper presents a multi-criteria evaluation methodology for nuclear fuel cycle options in terms of energy sustainability. Starting from the general sustainability concept and the public acceptance questionnaire, a set of indicators reflecting specific criteria for the evaluation of nuclear fuel cycle options are defined. Particular attention is devoted to the resource utility efficiency, environmental effect, human health hazard and economic effect, which represent the different concerns of different stakeholders. This methodology also integrated a special mathematic processing approach, namely the Extentics Evaluation Method, which quantifies the human being subjective perception to provide the intuitionistic judgement and comparison for different options. The once-through option and reprocessing option of nuclear fuel cycle are examined by using the proposed methodology. The assessment process and result can give us some guidance in nuclear fuel cycle evaluation under the constraint of limited data. 展开更多
关键词 核燃料循环系统 多标准评估方法论 主观感知 核能
下载PDF
VIKOR Method-An Effective Compromising Ranking Technique for Decision Making
15
作者 Hamed Taherdoost Mitra Madanchian 《Macro Management & Public Policies》 2023年第2期27-33,共7页
The VIKOR(VlseKriterijumska Optimizacija I Kompromisno Resenje)method,which is a multi-criteria decision-making method,is examined in this paper.The VIKOR method,like other MCDM techniques such as the Technique for Or... The VIKOR(VlseKriterijumska Optimizacija I Kompromisno Resenje)method,which is a multi-criteria decision-making method,is examined in this paper.The VIKOR method,like other MCDM techniques such as the Technique for Order of Preference by Similarity to Ideal Solution(TOPSIS),is widely used to solve complex decision-making problems in various fields such as engineering,management,and finance.This paper provides an overview of the VIKOR method,including its application areas,advantages,and disadvantages.Besides,in this survey paper,the process steps of the VIKOR method are described,including determining the decision matrix,normalizing the matrix,determining the weights of the criteria,calculating the utility and regret values,calculating the VIKOR index,and finally ranking the alternatives.By providing an overview of the VIKOR method and its process steps,this paper aims to provide a better understanding of the method and its potential application in different decision-making contexts. 展开更多
关键词 Decision making Multi criteria decision making VIKOR method VlseKriterijumska Optimizacija I Kompromisno Resenje Multi attribute decision making
下载PDF
《小儿积滞病诊断标准》的制定研究
16
作者 李梅芳 马延宁 +2 位作者 蔡秋晗 李瑞本 胡思源 《中华中医药学刊》 CAS 北大核心 2024年第5期57-61,共5页
目的制定一个框架清晰、指标明确、可操作性强的《小儿积滞病诊断标准》,为中医儿科临床实践和中医药临床评价提供依据。方法基于文献研究法,结合课题组经验,初步制定确立小儿积滞病诊断标准框架和各层面条目;基于共识法(包括德尔菲法... 目的制定一个框架清晰、指标明确、可操作性强的《小儿积滞病诊断标准》,为中医儿科临床实践和中医药临床评价提供依据。方法基于文献研究法,结合课题组经验,初步制定确立小儿积滞病诊断标准框架和各层面条目;基于共识法(包括德尔菲法、名义小组法)征求专家意见,最终制定形成《小儿积滞病诊断标准》。结果制定了由“病史、病程、诊断指标、需要排除的疾病、诊断条件”5个层面的小儿积滞病诊断标准。结论本研究采用的研究方法得当,保证了内容的全面性和结果的客观性,《小儿积滞病诊断标准》具有科学性、实用性,可供小儿积滞病的临床科研与医疗工作者参考使用。该诊断标准已通过中华中医药学会的审核发布(编号T/CACM1387-2022)。 展开更多
关键词 小儿积滞 诊断标准 德尔菲法 名义小组法
下载PDF
改扩建高速公路桥梁可用性评判与延寿准则
17
作者 赵尚传 左新黛 王少鹏 《公路交通科技》 CAS CSCD 北大核心 2024年第9期132-140,共9页
针对高速公路改扩建工程中既有桥梁是否能继续使用问题,综合考虑总体技术状况、承载力状况、剩余耐久年限状况3个层次,创建了以桥梁构件类别的外观耐久状态为一级指标、以剩余耐久年限为二级指标的评判方法,提出了表征构件剩余耐久年限... 针对高速公路改扩建工程中既有桥梁是否能继续使用问题,综合考虑总体技术状况、承载力状况、剩余耐久年限状况3个层次,创建了以桥梁构件类别的外观耐久状态为一级指标、以剩余耐久年限为二级指标的评判方法,提出了表征构件剩余耐久年限的寿命系数和可用寿命系数,建立了既有桥梁的延寿准则和延寿策略,探讨了可用寿命系数与目标使用年限、单次延寿的有效保护年限、拟采取的维护措施类型数量的相互关系。以京沪高速改扩建工程为研究背景,选取9座既有桥梁为典型桥梁,按100 a目标使用年限,计算得到构件主筋和箍筋的剩余耐久年限,给出了典型桥梁主体构件剩余耐久年限。根据可用评判方法,计算得到了在相同延寿措施下的延寿年限、延寿费用及可用寿命系数,按经济最优原则提出了从A级到E级共计5种延寿方式。研究表明,京沪高速改扩建工程典型桥梁按箍筋计算得到构件耐久寿命比按主筋计算值低,建议构件年限按箍筋计算值取用;目标使用年限为100 a时,主梁构件可正常使用比例为94%,墩柱单元、盖梁单元、桥台单元的可正常使用比例分别为67%,11%,44%。实际工程表明,采用该评判方法的评判结果与结构实际状态基本相符,与工程实际采取的处置措施基本相当,验证了该方法的合理性。 展开更多
关键词 桥梁工程 延寿准则 评判方法 主体构件 耐久年限 改扩建
下载PDF
水利工程施工的IT2FS-MARCOS风险评价 被引量:1
18
作者 孙开畅 薛文丽 +1 位作者 李婷婷 陈千庆 《水力发电学报》 CSCD 北大核心 2024年第7期109-120,共12页
为解决专家决策的主观性造成的风险评价不确定性和不同风险参数权重下考虑多种风险因子评价问题,这里提出一种基于IT2FS-MARCOS法的水利工程施工风险评价方法。首先确定水利工程施工风险指标评估体系,运用最优最劣法(BWM)融合基于层间... 为解决专家决策的主观性造成的风险评价不确定性和不同风险参数权重下考虑多种风险因子评价问题,这里提出一种基于IT2FS-MARCOS法的水利工程施工风险评价方法。首先确定水利工程施工风险指标评估体系,运用最优最劣法(BWM)融合基于层间相关性的客观赋权法(CRITIC)的组合赋权法对各风险参数的权重进行分析;然后引入区间2型模糊集(IT2FS)改进多准则决策中的基于折衷方案的备选方案排序法(MARCOS)计算各风险因素的效用函数值,基于效用函数值进行风险因素分析和评价。结合工程实例应用,表明:地质、天气条件和作业计划安排等风险因素危险程度较高,其中地质条件对该施工项目安全威胁最大,为水利工程施工需重点管理的风险因子。该模型的特点是不仅考虑了专家评价的模糊性,而且采用多准则决策方法避免对风险参数简单加权,与优劣解距离法(TOPSIS)相比,本方法与工程实际符合得更好,有望为处理水利工程不确定信息下的风险评价提供一种新的思路。 展开更多
关键词 水利工程施工 风险评价 BWM-CRITIC组合赋权法 区间2型模糊集 多准则决策 IT2FS-MARCOS法
下载PDF
多冷媒非均质人工冻结壁弹塑性应力分析
19
作者 王彬 梁秀玲 +2 位作者 张子浩 蔡海兵 荣传新 《煤田地质与勘探》 EI CAS CSCD 北大核心 2024年第9期106-120,共15页
【目的】受制冷媒介温度差异以及被冻地层与冻结管距离差异的影响,多冷媒联合双排管冻结壁的非均匀性较为显著,为了合理评价该类冻结壁的安全性,需开展考虑非均质性的多冷媒人工冻结壁弹塑性应力分析。【方法】选取距离1/4管距处的冻结... 【目的】受制冷媒介温度差异以及被冻地层与冻结管距离差异的影响,多冷媒联合双排管冻结壁的非均匀性较为显著,为了合理评价该类冻结壁的安全性,需开展考虑非均质性的多冷媒人工冻结壁弹塑性应力分析。【方法】选取距离1/4管距处的冻结壁作为特征截面,将该截面上的温度分布曲线等效成三段一次函数形式,并将冻结壁视为随温度成线性变化的非均质材料,分别基于4种冻土屈服准则,推导得出多冷媒联合双排管非均质冻结壁弹塑性应力解析表达式。基于该解析表达式,对多冷媒冻结壁的受力特性进行计算,并将该计算结果与均质冻结壁计算得出的结果进行对比。【结果和结论】研究发现:(1)在盐水-二氧化碳联合双排管冻结壁中,径向应力随着相对半径r的增加而上升,环向应力在不同冻结区间(Ⅰ、Ⅱ、Ⅲ)表现出不同的变化趋势。(2)基于均质冻结壁计算理论,弹性极限状态的冻结壁的环向应力最大值出现在冻结壁内侧,弹塑性状态的冻结壁的环向应力最大值出现在弹塑性分界面处,塑性极限状态的冻结壁的环向应力最大值出现在冻结壁最外侧;而基于非均质冻结壁计算理论,冻结壁环向应力最大值始终出现在冻结壁分区界线(r=2)处。(3)在考虑非均质特性后,冻结壁的弹性极限承载力降低1.8%,而塑性极限承载力提高8.1%。在弹塑性状态下,对应相同塑性区相对半径,非均质冻结壁具有更高的承载力,且这种现象随着塑性区相对半径的增大而愈发明显。研究成果对富水地层多冷媒联合冻结帷幕的设计具有重要的参考价值。 展开更多
关键词 人工地层冻结法 双排管冻结壁 多冷媒联合冻结帷幕 非均质 屈服准则 弹塑性分析
下载PDF
学生增值评价的研究与实践——以基于成果导向的动物外科手术课程为例
20
作者 孙洪梅 孙英杰 +3 位作者 蔡皓璠 王雪东 邹继新 于雪梅 《黑龙江水产》 2024年第3期359-364,共6页
学生增值评价注重自身基础,关注学习过程,强调增值发展,有助于增强学习自信心、提升学生职业技能。动物外科手术在增值评价中根据教学成果(即教学目标)设计评价维度,实现多元主体,采用多元评价方法,制定增值评价标准并运用,从而实现人... 学生增值评价注重自身基础,关注学习过程,强调增值发展,有助于增强学习自信心、提升学生职业技能。动物外科手术在增值评价中根据教学成果(即教学目标)设计评价维度,实现多元主体,采用多元评价方法,制定增值评价标准并运用,从而实现人才培养目标。通过学生增值性评价的研究与实践,希望对学生综合评价的实施产生重要参考价值,并在今后的研究中不断改进完善。 展开更多
关键词 增值评价 评价维度 评价主体 评价方法 评价标准
下载PDF
上一页 1 2 56 下一页 到第
使用帮助 返回顶部