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Challenges in the Transition and Transfer of Young Adults with Congenital Heart Disease in Latin America and the Caribbean: The “Timeliness Principle”
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作者 John J.Araujo 《Congenital Heart Disease》 2025年第1期61-75,共15页
Today,more than 90%of children who are born with congenital heart disease survive and reach adulthood,especially in developed countries.Consequently,the population of adults with congenital heart disease has increased... Today,more than 90%of children who are born with congenital heart disease survive and reach adulthood,especially in developed countries.Consequently,the population of adults with congenital heart disease has increased signiffcantly over the last few decades.In Latin America and the Caribbean countries,this same scenario is occurring at an accelerated pace.Loss to follow-up is a global problem in adults with congenital heart disease,ranging from 30–60%.In Latin America and Caribbean countries,it is estimated that less than 10%of adults with congenital heart disease are being followed.The small number of specialists and adult congenital heart disease specialized centers,as well as virtually nonexistent transition and transfer programs,are some of the reasons for this.This article is a narrative review of the current status of the transition and transfer of young adults with congenital heart disease,with a special focus on Latin America and Caribbean countries.It describes the general concepts of transition and transfer,analyzes barriers and,ffnally,presents specialized care alternatives that would reduce losses and improve this population’s care. 展开更多
关键词 Adults with congenital heart disease transition and transfer loss to follow-up transition program Latin America and the Caribbean
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Goal Programming for Stable Mode Transition in Tandem Turbo-ramjet Engines 被引量:16
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作者 Chen Min Tang Hailong Zhu Zhili 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2009年第5期486-492,共7页
This article, in order to guarantee the stable mode transition in tandem turbo-ramjet engines, investigates the multi-objective and multi-variable goal programming algorithm. First, it introduces the structural featur... This article, in order to guarantee the stable mode transition in tandem turbo-ramjet engines, investigates the multi-objective and multi-variable goal programming algorithm. First, it introduces the structural features of the variable cycle turbo-ramjet engines, the principles of selecting the mode transition operation point and the design parameters, and the characteristics of the turbofan mode and the ramjet mode. Second, a component-based variable cycle turbo-ramjet engine model is developed to simulate the mode transition process. Third, the Newton-Raphson algorithm is used to solve the multi-variable and multi-objective optimization problem. The results show that with the maximum residua of only 0.06%, this algorithm has an acceptable convergence that meets the predetermined goals. Finally, the simulation shows that the stable turbo-ramjet mode transition could be realized with the mode transition control law developed by the algorithm. 展开更多
关键词 PROPULSION transition goal programming algorithm turbine-based combine cycle engine turbofan engine ramjetengine HYPERSONIC
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Maternally-preset program of apoptosis and caspases involved in execution of the apoptosis at midblastula transition (MBT) but not before in <i>Xenopus laevis</i>embryogenesis
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作者 Koichiro Shiokawa 《Advances in Bioscience and Biotechnology》 2012年第6期751-769,共19页
To study gene control mechanisms in Xenopus embryos, we analyzed polyamines, cloned SAMDC (S-adenosylmethionine decarboxylase), a key enzyme of polyamine metabolism, and microinjected its mRNA into Xenopus fertilized ... To study gene control mechanisms in Xenopus embryos, we analyzed polyamines, cloned SAMDC (S-adenosylmethionine decarboxylase), a key enzyme of polyamine metabolism, and microinjected its mRNA into Xenopus fertilized eggs. The microinjection induced a large increase in SAMDC activity, exhaustion of the substrate SAM (S-adenosylmethionine), and execution of apoptosis at the stage called midblastula transition (MBT). By tracing GFP (green fluorescence protein)-marked apoptotic cells, we reached a conclusion that the apoptosis provides pre-blastula embryos with a fail-safe mechanism of early development. We analyzed caspase mRNAs and found that caspase-9 and -3 mRNAs are maternal mRNA and activation of caspase-9 is one of the key steps for the execution of the apoptosis. We also found that over- expression of caspase-8, and in addition p53, a tumor suppressor protein, also induces apoptosis at MBT, just like the overexpression of SAMDC and caspase-9 does. The apoptosis induced by p53 was suppressed by Xdm-2, a negative regulator of p53, and by a peptide inhibitor and a dominant-negative type mutant of caspase-9, but not by those of caspase-8. By contrast, apoptosis induced by SAMDC was suppressed by peptide inhibitors and dominant-negative mutants of both caspase-9 and caspase-8, but not by Xdm-2. Unlike caspase-9 mRNA, caspase-8 mRNA was not a maternal mRNA, but newly expressed during cleavage stage (pre-MBT stage) only in embryos overexpressed with SAMDC. In SAMDC-induced apoptotic embryos activities to process procaspase-8 and procaspase-9 appeared, whereas in p53-induced apoptotic embryos only activity to process procaspase-9 appeared. Thus, Xenopus embryos have at least two pathways to execute the maternal program of apoptosis: One induced by SAMDC overexpression through activation of caspase-9 and do novo expression of caspase-8 gene, and the other induced by p53 overexpression through activation of caspase-9 but not caspase-8. In Xenopus embryos, it has long been believed that zygotic genes are silent until MBT, but results obtained with caspase-8 may provide a novel example of gene expression before MBT. 展开更多
关键词 Maternal program of APOPTOSIS Midblastula transition (MBT) Polyamines S-Adenosylmethionine Decaroboxylase (SAMDC) Xenopus LAEVIS Em-bryos CASPASES p53 pre-MBT Transcription
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Islay3D—A Programming Environment for Authoring Interactive 3D Animations in Terms of State-Transition Diagram
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作者 Dandy Ling Kwong Michitoshi Niibori +2 位作者 Shusuke Okamoto Masaru Kamada Tatsuhiro Yonekura 《Journal of Software Engineering and Applications》 2014年第3期177-186,共10页
An educational programming language is a programming language that is designed primarily as a learning instrument and not so much as a tool for writing programs for production. Three-dimensional (3D) interactive anima... An educational programming language is a programming language that is designed primarily as a learning instrument and not so much as a tool for writing programs for production. Three-dimensional (3D) interactive animations provide an effective means to engage the attention of the audience to learn programming language. Traditionally, creating 3D games had been difficult as it requires specialized programming skills. However, it had been proven that the state-transition diagram, which is the most fundamental principle for automata, is intuitively so comprehensive that even children can create programs for interactive animations and video games in the two-dimensional world. Islay3D is a programming environment for authoring interactive 3D animations based on this concept. In this paper, the Islay3D animation language is introduced, where a character is modeled as an object, and its behavior is defined in term of a set of state-transition diagrams. The interpretation of the state-transition diagrams to JavaScript is also presented. Finally, the web-based programming environment is introduced. With the web-based platform, the public will be able express their creativity in creating interactive 3D animations and video games easily from within their browser. 展开更多
关键词 3D Visual programming Language Computer GAMES State transition DIAGRAM Web Service
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Risk adjustable optimal operation for electricity-hydrogen integrated energy system based on chance constrained goal programming
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作者 ZHOU Xiao-jun HU Jia-ming +1 位作者 LI Chao-jie YANG Chun-hua 《Journal of Central South University》 2025年第6期2224-2238,共15页
The electricity-hydrogen integrated energy system(EH-IES)enables synergistic operation of electricity,heat,and hydrogen subsystems,supporting renewable energy integration and efficient multi-energy utilization in futu... The electricity-hydrogen integrated energy system(EH-IES)enables synergistic operation of electricity,heat,and hydrogen subsystems,supporting renewable energy integration and efficient multi-energy utilization in future low carbon societies.However,uncertainties from renewable energy and load variability threaten system safety and economy.Conventional chance-constrained programming(CCP)ensures reliable operation by limiting risk.However,increasing source-load uncertainties that can render CCP models infeasible and exacerbate operational risks.To address this,this paper proposes a risk-adjustable chance-constrained goal programming(RACCGP)model,integrating CCP and goal programming to balance risk and cost based on system risk assessment.An intelligent nonlinear goal programming method based on the state transition algorithm(STA)is developed,along with an improved discretized step transformation,to handle model nonlinearity and enhance computational efficiency.Experimental results show that the proposed model reduces costs while controlling risk compared to traditional CCP,and the solution method outperforms average sample sampling in efficiency and solution quality. 展开更多
关键词 electricity-hydrogen integrated energy system chance constrained goal programming risk adjustment state transition algorithm
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平图的transition多项式的Maple计算
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作者 李美莲 邓青英 《山东大学学报(理学版)》 CAS CSCD 北大核心 2018年第10期27-34,共8页
将现有的计算方法改进得到了一种新的计算平图的transition多项式的方法。算法使用了圈置换的方法计算每个transition操作所产生的欧拉圈的数目。利用M aple软件编写出了该算法的程序,通过这个程序,可以实现任意一个平图的transition多... 将现有的计算方法改进得到了一种新的计算平图的transition多项式的方法。算法使用了圈置换的方法计算每个transition操作所产生的欧拉圈的数目。利用M aple软件编写出了该算法的程序,通过这个程序,可以实现任意一个平图的transition多项式的计算。 展开更多
关键词 平图 4-正则图 transition多项式 Maple程序
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Parameter Estimation in Logistic Regression for Transition, Reverse Transition and Repeated Transition from Repeated Outcomes
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作者 Rafiqul I. Chowdhury M. Ataharul Islam +1 位作者 Shahariar Huda Laurent Briollais 《Applied Mathematics》 2012年第11期1739-1749,共11页
Covariate dependent Markov models dealing with estimation of transition probabilities for higher orders appear to be restricted because of over-parameterization. An improvement of the previous methods for handling run... Covariate dependent Markov models dealing with estimation of transition probabilities for higher orders appear to be restricted because of over-parameterization. An improvement of the previous methods for handling runs of events by expressing the conditional probabilities in terms of the transition probabilities generated from Markovian assumptions was proposed using Chapman-Kolmogorov equations. Parameter estimation of that model needs extensive pre-processing and computations to prepare data before using available statistical softwares. A computer program developed using SAS/IML to estimate parameters of the model are demonstrated, with application to Health and Retirement Survey (HRS) data from USA. 展开更多
关键词 COMPUTER program MARKOV Model transition REVERSE transition Repeated transition
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On Transit Gait Programming of Six-legged Wall-climbing Robot
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作者 钱晋武 龚振邦 张启先 《Advances in Manufacturing》 SCIE CAS 1997年第1期42-47,共6页
Transit gait programming is a key problem for a multi-legged robot to climb automatically from the ground up the wall, as well as between wall intersections. In this paper, a new idea is put forward by which the compl... Transit gait programming is a key problem for a multi-legged robot to climb automatically from the ground up the wall, as well as between wall intersections. In this paper, a new idea is put forward by which the complex transit gait is decomposed into a sequence of two relatively simpler parts - single-leg motion and body pitching motion. An algorithm based on the above concept shows its feasibility and effectiveness in the graphic kinematics simulation. 展开更多
关键词 wall-climbing robot. ground-to-wall transit gait kinematics simulation gait programming
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Integrated Optimization of Timetable and Rolling Stock Circulation under Mixed Usages of Short-length and Full-length Services in Urban Rail Transit 被引量:1
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作者 Jing Teng Jinke Gao Pengling Wang 《Journal of Harbin Institute of Technology(New Series)》 CAS 2024年第6期1-15,共15页
The rapid growth of passenger flow in urban rail transit has led to great service pressures for metro companies in organizing train services to provide higher transportation capacities in order to satisfy passengers&#... The rapid growth of passenger flow in urban rail transit has led to great service pressures for metro companies in organizing train services to provide higher transportation capacities in order to satisfy passengers' travel demand, especially on those metro lines with insufficient rolling stock. In order to cope with high passenger flow service pressure, a mixed integer nonlinear programming(MINLP) model is proposed to optimize the line plan, timetable and rolling stock circulation simultaneously, to reduce the number of rolling stocks and increase the number of full-length services. A two-step algorithm strategy is proposed. In the first stage, the train timetable is optimized under the assumption that all the train services are the full-length services. In the second stage, the rolling stock plan is optimized based on the timetable optimized in the first stage. To ensure a feasible rolling stock circulation, certain full-length services are shortened to the short-length services due to the limited number of rolling stocks. Numerical experiments are performed based on the real-life data of Shanghai Metro Line 8. Results show that the proposed method can efficiently optimize the timetable and rolling stock circulation of the whole operation day. The optimized results are beneficial for both the service and the operational costs. 展开更多
关键词 urban rail transit mixed integer nonlinear programming timetable design rolling stock circulation
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Bi-Level Programming for the Optimal Nonlinear Distance-Based Transit Fare Structure Incorporating Principal-Agent Game
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作者 Xin Sun Shuyan Chen Yongfeng Ma 《Journal of Harbin Institute of Technology(New Series)》 CAS 2022年第5期69-77,共9页
The urban transit fare structure and level can largely affect passengers’travel behavior and route choices.The commonly used transit fare policies in the present transit network would lead to the unbalanced transit a... The urban transit fare structure and level can largely affect passengers’travel behavior and route choices.The commonly used transit fare policies in the present transit network would lead to the unbalanced transit assignment and improper transit resources distribution.In order to distribute transit passenger flow evenly and efficiently,this paper introduces a new distance-based fare pattern with Euclidean distance.A bi-level programming model is developed for determining the optimal distance-based fare pattern,with the path-based stochastic transit assignment(STA)problem with elastic demand being proposed at the lower level.The upper-level intends to address a principal-agent game between transport authorities and transit enterprises pursing maximization of social welfare and financial interest,respectively.A genetic algorithm(GA)is implemented to solve the bi-level model,which is verified by a numerical example to illustrate that the proposed nonlinear distance-based fare pattern presents a better financial performance and distribution effect than other fare structures. 展开更多
关键词 bi-level programming model principal-agent game nonlinear distance-based fare path-based stochastic transit assignment
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城市轨道交通网络韧性优化研究 被引量:6
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作者 张开冉 殷苏平 蒋明君 《安全与环境学报》 北大核心 2025年第2期527-535,共9页
修复策略优化是提高突发事件发生后城市轨道交通网络韧性的重要手段。当前的研究多集中在单一层面的韧性评估,对乘客出行行为的考虑也较少关注对网络熟悉度的随机性。为此构建了城市轨道交通网络韧性优化双层模型,以提高网络对不利因素... 修复策略优化是提高突发事件发生后城市轨道交通网络韧性的重要手段。当前的研究多集中在单一层面的韧性评估,对乘客出行行为的考虑也较少关注对网络熟悉度的随机性。为此构建了城市轨道交通网络韧性优化双层模型,以提高网络对不利因素的应对能力。综合考虑多个层面提出了恢复速度和网络性能双韧性指标,以双韧性指标最大化为目标,考虑乘客出行行为决策,构建了基于修复策略的韧性优化双层模型。并以杭州地铁网络作为实际案例进行验证分析。结果表明:模型所求的修复策略优于其他修复策略;在一定范围内恢复速度韧性随着预算修复资金增加而减小,网络性能韧性随之增大而增大,恢复速度韧性随着修复队伍数量增大而增大,网络性能韧性随之增大而减小。 展开更多
关键词 安全系统学 城市轨道交通网络 韧性优化 客流分配 双层规划 修复策略
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新疆地热资源分布、成因及开发利用方向:第三次新疆综合科学考察地热科考成果综述
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作者 孔彦龙 董远卓 +26 位作者 叶灿滔 程远志 乃尉华 庞忠和 马伟斌 张健 龚宇烈 李义曼 姜光政 王迎春 古丽波斯坦·吐逊江 田小明 李棱雪 师德扬 张程凯 田逸楠 李斌 陈锋 张磊 王珂 任亚倩 张伟尊 罗冠中 段佳斌 陈娅奎 张小雷 汪集暘 《地学前缘》 北大核心 2026年第1期283-295,共13页
基于“冷壳冷幔”的理论认识,新疆一直被认为是地热资源相对贫瘠的地区,其总体勘查和开发利用情况远落后于内地。第三次新疆综合科学考察课题“地热等清洁能源资源综合调查与评价”在收集整理全疆地热已有成果的基础上,重点开展野外补... 基于“冷壳冷幔”的理论认识,新疆一直被认为是地热资源相对贫瘠的地区,其总体勘查和开发利用情况远落后于内地。第三次新疆综合科学考察课题“地热等清洁能源资源综合调查与评价”在收集整理全疆地热已有成果的基础上,重点开展野外补充调查,新发现了地热点位11处,补充确定了地热资源赋存形式2种,估算新疆地热资源量折合超过18亿吨标准煤。调查结果显示,新疆地热资源主要分布于盆间隆起山地,与其主要人口分布保持高度一致,而较少的人口基数决定了新疆人均地热资源量较高,反而说明了其具有较大的开发利用潜力。新疆地热资源表现出“北疆禀赋差,南疆禀赋好”的分布格局:北疆天山、阿勒泰山地区广泛发育以断裂深循环成因的中低温水热型地热资源,而在南疆帕米尔高原,受印度欧亚板块碰撞的影响,形成了目前新疆唯一发现的高温地热资源。然而,新疆地热资源开发利用整体水平相对较低,开发利用方式单一,以洗浴保健和旅游疗养为主,且主要在经济发展较好、交通较方便的北疆,南疆地热开发利用程度较低。通过本次科学考察摸清了新疆地热资源分布与开发利用现状情况,结合新疆国土空间规划,围绕新疆“双碳”发展战略,课题组提出新疆地热能源资源开发利用路线建议:在南疆塔什库尔干塔吉克自治县等地区推动“地热发电+综合利用”发展,在北疆温泉县等地区大力推进“地热+”综合能源开发,在乌昌石城市群全面深化浅层、中深层岩土地热能利用。 展开更多
关键词 第三次新疆综合科学考察 能源转型 资源禀赋 地热开发 地热发电 地热供暖
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城轨车底出段时空路径与列车时刻表一体化优化研究
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作者 李超 唐金金 +3 位作者 白紫熙 赵晴晴 董秋含 邵欣昀 《铁道学报》 北大核心 2025年第2期24-34,共11页
为在满足乘客出行需求的条件下降低列车运行成本,确保列车运行图的可行性,重点针对车底出段时空路径与时刻表一体化优化问题进行研究。其中,车底出段时空路径规划问题用于确定车底的出段位置及其驶入正线车站的到达时间,时刻表问题用于... 为在满足乘客出行需求的条件下降低列车运行成本,确保列车运行图的可行性,重点针对车底出段时空路径与时刻表一体化优化问题进行研究。其中,车底出段时空路径规划问题用于确定车底的出段位置及其驶入正线车站的到达时间,时刻表问题用于确定担当运输任务列车的到发时刻。车底出段时空路径及时刻表的合理性是列车运行图可行性的重要保障。引入列车区间运行模式作为状态维度,构建描述车底运行的时空状态网络。基于此,进一步考虑客流需求与列车运行约束,以最小化列车运行成本与乘客出行成本为目标,实现车底出段时空路径与列车时刻表的一体化优化。通过拉格朗日松弛,将原问题转化为经典的最短路搜索问题,并提出启发式动态规划算法进行求解。以重庆地铁3号线为例验证模型与算法的有效性,结果表明:相比基于经验编制得到的列车运行计划,该模型与算法能够有效地降低乘客的出行成本和企业的运营成本,列车运行计划的总成本降低27.18%。 展开更多
关键词 城市轨道交通 出段时空路径 列车时刻表 时空状态网络 启发式动态规划
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基于Hybrid A^(*)与最优控制的农机精准进田转场轨迹规划方法
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作者 迟瑞娟 付国辉 +4 位作者 马悦琦 班超 苏童 陈嘉翊 李知旻 《农业机械学报》 北大核心 2025年第10期321-331,共11页
狭窄机耕道环境下,农机进田转场轨迹规划影响农机行驶轨迹平滑性和进田作业质量和效率。针对目前农机路径规划在狭窄空间转弯处的轨迹曲率较大、不够平滑和速度规划不够精准,不利于取得较好跟踪效果等问题,本文提出一种基于Hybrid A^(*... 狭窄机耕道环境下,农机进田转场轨迹规划影响农机行驶轨迹平滑性和进田作业质量和效率。针对目前农机路径规划在狭窄空间转弯处的轨迹曲率较大、不够平滑和速度规划不够精准,不利于取得较好跟踪效果等问题,本文提出一种基于Hybrid A^(*)与最优控制的农机精准进田转场轨迹规划方法。获取先验转场的栅格地图、起始位姿和目标位姿,采用Hybrid A^(*)算法获取满足农机运动学约束的最优或者较优转场路径;对路径节点配置时间信息,并通过数据预处理得到非线性问题求解所需初始解;采用最优控制问题的方法,在农机运动学约束、两点边值约束、动力学约束和避障约束等多约束条件下,建立缩短转场时间、提高农机操纵性和提升轨迹平滑性多优化目标代价函数;将最优控制问题转换为非线性规划(NLP)问题,且采用非线性求解器求解,得到农机进田转场轨迹和速度序列。并以洋马VP6E型插秧机作为实验平台,在农机车头背向进田通道和车头朝向进田通道2种场景中进行仿真与实车实验。实验结果表明,轨迹平均曲率为0.231 2~0.251 7 m-1,轨迹平滑性较好,符合车辆运动学特性;在轨迹跟踪实车实验中,平均绝对横向偏差为1.56~2.59 cm,平均绝对航向角偏差为0.97°~1.54°,最大绝对速度偏差为0.058~0.102 m/s,平均绝对速度为0.454~0.528 m/s,因此,插秧机有效跟踪本文轨迹规划方法生成的轨迹,实现了插秧机在狭窄机耕道上精准、快速地进田转场。 展开更多
关键词 精准转场 轨迹规划 最优控制 Hybrid A^(*) 非线性规划 轨迹跟踪
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基于双层规划的城市轨道交通运营中期票价制定方法研究
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作者 康拥政 陈曦 《铁道运输与经济》 北大核心 2025年第9期127-134,共8页
城市轨道交通作为居民主要的出行方式之一,其票价合理性直接影响着人们是否选择这种交通方式。为了探索制定轨道交通运营中期的合理定价策略,建立旨在实现居民出行效用最大化和运营成本最小化的双层规划定价模型。通过分析国内外定价方... 城市轨道交通作为居民主要的出行方式之一,其票价合理性直接影响着人们是否选择这种交通方式。为了探索制定轨道交通运营中期的合理定价策略,建立旨在实现居民出行效用最大化和运营成本最小化的双层规划定价模型。通过分析国内外定价方面研究现状,总结现有研究的不足之处,并对现有票制和票价方案进行综合分析,构建居民出行效用函数,对影响因素进行量化,建立双层规划模型。基于实际工程案例进行求解验证,发现轨道交通运营的经济效益随票价的增长而增大,但增长到一定程度后又会随之下降,得到能够使出行者和轨道交通运营企业都能接受的票价方案,为城市轨道交通的定价提供理论依据。研究结果有助于优化轨道交通的票价策略,提升其服务水平,促进城市可持续发展。 展开更多
关键词 轨道交通 票价制定 票制选择 双层规划 效用函数
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基于快速通勤需求的地铁列车跨站停车方案优化
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作者 江志彬 王炳勋 +2 位作者 李洪运 赵源 金晓琴 《同济大学学报(自然科学版)》 北大核心 2025年第3期410-419,共10页
AB跨站停车方案可以满足高峰时段地铁通勤线路场景下的乘客快速出行需求。在充分考虑乘客换乘便利性和候车安全性的基础上,以最小化乘客总旅行时间并兼顾换乘乘客的公平性影响为目标,基于出行过程和换乘类别建立了地铁AB跨站停车0-1整... AB跨站停车方案可以满足高峰时段地铁通勤线路场景下的乘客快速出行需求。在充分考虑乘客换乘便利性和候车安全性的基础上,以最小化乘客总旅行时间并兼顾换乘乘客的公平性影响为目标,基于出行过程和换乘类别建立了地铁AB跨站停车0-1整数规划模型,并设计了高效的变邻域搜索算法,最后以上海地铁11号线为例验证了模型和算法的有效性。结果表明:变邻域搜索算法相较于遗传算法可在短时间内搜索得到较优解,能够很好地适用于AB跨站停车优化模型;AB跨站停车方案人均旅行时间可节省2.91 min,考虑人工经验策略的AB跨站停车方案人均旅行时间可节省2.12 min,且换乘乘客数量可减少41.18%;通过灵敏度分析可以得出,换乘站候车时间惩罚系数、列车始发间隔时间和最大AB类车站间隔是影响优化结果的关键因素。 展开更多
关键词 城市轨道交通 列车停站方案 0-1整数规划 变邻域搜索算法 快速通勤需求 AB跨站停车
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降低平面接刀痕的加工方法的创新研究
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作者 李学飞 王虎 +1 位作者 郭东胜 于庆峰 《内燃机与配件》 2025年第18期67-70,共4页
针对机械加工中高精度平面存在的接刀痕问题,本文从工艺优化与数控编程角度提出创新解决方案。通过分析接刀痕的成因(如机床精度不足、切削热变形、刀具磨损及参数设置不合理),重点研究了圆弧进刀退刀法、恒定进给率控制、轨迹圆弧过渡... 针对机械加工中高精度平面存在的接刀痕问题,本文从工艺优化与数控编程角度提出创新解决方案。通过分析接刀痕的成因(如机床精度不足、切削热变形、刀具磨损及参数设置不合理),重点研究了圆弧进刀退刀法、恒定进给率控制、轨迹圆弧过渡及摆线铣削等工艺优化方法。实验表明,摆线铣削法通过连续摆线轨迹减少换向次数,结合顺铣方式与参数优化(侧吃刀量0.4~0.6 mm、进给量300~1200 mm/min),可显著降低接刀痕尺寸至0.03 mm以下,同时提升加工效率20%~30%。此外,采用高精度刀具与智能切削参数实时调整技术,有效替代传统磨削工艺,降低了加工成本。研究结果为高精度平面加工提供了可推广的技术路径。 展开更多
关键词 平面加工 接刀痕 摆线铣削 切削参数优化 数控编程 圆弧过渡
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大型活动下城轨车站客流协同控制及优化
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作者 左忠义 杨欣然 《大连交通大学学报》 2025年第1期9-14,38,共7页
大型活动散场时段的短时大客流需求具有空间分布失衡性,易造成城市轨道交通站台出现乘客聚集现象,不仅影响乘客乘车的舒适度,还存在安全事故隐患。为解决该问题,将乘客进站与列车运行时间离散化,以乘客最佳进站人数与列车运行长短交路... 大型活动散场时段的短时大客流需求具有空间分布失衡性,易造成城市轨道交通站台出现乘客聚集现象,不仅影响乘客乘车的舒适度,还存在安全事故隐患。为解决该问题,将乘客进站与列车运行时间离散化,以乘客最佳进站人数与列车运行长短交路作为决策变量,基于客流演化与列车运行的动态关系,建立以乘客总等待时间和列车运行时间最小化为目标的多站联合限流与长短交路开行方案协同优化模型,并运用蜂群优化算法进行模型求解。以某轨道交通线路为例,验证模型的有效性。结果表明,与常规运营策略相比,协同优化策略下运营成本减少了5.3%,乘客等待时间减少了19.2%,实现了对大型活动背景下车站短时大客流的有效控制。 展开更多
关键词 城市轨道交通 多目标规划 蜂群算法 客流协同控制 优化策略
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基于乘客密度的城市轨道交通站台照明节能控制方法
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作者 毛建 张宁 +5 位作者 章澜岚 王澳庆 刘家俊 张恒文 王浩 温龙辉 《都市快轨交通》 北大核心 2025年第3期71-78,共8页
当前城市轨道交通站台照明控制方法存在着控制方式简单、控制准确度低等问题,导致能耗严重浪费,也无法为乘客提供舒适的照明环境。根据城轨站台客流特点,结合站台区域功能特征和乘客心理需求,提出一种基于乘客密度的城轨站台照明节能控... 当前城市轨道交通站台照明控制方法存在着控制方式简单、控制准确度低等问题,导致能耗严重浪费,也无法为乘客提供舒适的照明环境。根据城轨站台客流特点,结合站台区域功能特征和乘客心理需求,提出一种基于乘客密度的城轨站台照明节能控制方法。该方法首先通过分析城轨站台空间特征和乘客心理时间变化特点,建立站台不同时段不同区域乘客密度和站台区域照度的函数关系,然后建立以站台照明能耗最优为目标,站台照度需求为约束,灯具调光系数为控制变量的线性规划优化模型,最后采用单纯形法对模型进行求解并进行实例分析。结果表明,在小客流车站,本文方法与目前常规控制方式相比,在早高峰、晚高峰和平峰时段,站台照明能耗降低分别达27.68%、38.16%和38.87%,并保证区域照度在合理区间,可以有效降低城轨站台照明能耗,提高站台光环境舒适性。 展开更多
关键词 城轨站台 照明节能 乘客密度 线性规划 单纯形法
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Fund budget model for multipurpose transit smart card systems
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作者 张宁 钱振东 +1 位作者 陈恺 杨利强 《Journal of Southeast University(English Edition)》 EI CAS 2008年第1期95-98,共4页
The fund budget of multipurpose transit smart card systems is studied by stochastic programming to assign limited funds to different applications reasonably. Under the constraints of a gross fund, models of chance-con... The fund budget of multipurpose transit smart card systems is studied by stochastic programming to assign limited funds to different applications reasonably. Under the constraints of a gross fund, models of chance-constrained and dependentchance for the fund budget of multipurpose transit smart card systems are established with application scale and social demand as random variables, respectively aiming to maximize earnings and satisfy the service requirements the furthest; and the genetic algorithm based on stochastic simulation is adopted for model solution. The calculation results show that the fund budget differs greatly with different system objectives which can cause the systems to have distinct expansibilities, and the application scales of some applications may not satisfy user demands with limited funds. The analysis results indicate that the forecast of application scales and application future demands should be done first, and then the system objective is determined according to the system mission, which can help reduce the risks of fund budgets. 展开更多
关键词 multipurpose transit smart card systems fund budgeting stochastic programming genetic algorithm
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