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中型挖掘机正流量控制特性的分析与改进 被引量:1
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作者 仉志强 宋建丽 +2 位作者 刘志奇 李永堂 贾跃虎 《液压气动与密封》 2012年第9期71-74,共4页
分析了双执行机构的正流量控制原理,重点从三个方面对正流量控制特性进行了研究:首先分析了挖掘机调速区间,采用了能满足精调特性和快速特性的双折线式调速曲线,以此曲线作为调速特性的设计目标;再者从调速区的大小、精调特性和快速特... 分析了双执行机构的正流量控制原理,重点从三个方面对正流量控制特性进行了研究:首先分析了挖掘机调速区间,采用了能满足精调特性和快速特性的双折线式调速曲线,以此曲线作为调速特性的设计目标;再者从调速区的大小、精调特性和快速特性三方面比较了比例式泵流量调节曲线和双折线式泵流量曲线的优缺点;最后分析了当前旁路回油阀的控制思路,提出了基于瞬时流量不饱和度的实时控制原则。理论分析表明,新方案能够改善系统的控制特性。 展开更多
关键词 挖掘机 流量 旁路回油 泵阀复合调速 瞬时流量饱和度
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交通信号优化设置模型的建立与求解 被引量:1
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作者 李巧艳 黄钰斌 吴功策 《山东工业技术》 2018年第3期206-206,228,共2页
交通信号控制系统是集现代计算机、通信和控制技术于一体的区域交通信号实时联网控制系统本文通过从交通状况的表征公式入手,建立了交通配时周期的可行域与交叉路口流量以及路口总损失时间之间的联系,最终建立以平均延误时间最小为目标... 交通信号控制系统是集现代计算机、通信和控制技术于一体的区域交通信号实时联网控制系统本文通过从交通状况的表征公式入手,建立了交通配时周期的可行域与交叉路口流量以及路口总损失时间之间的联系,最终建立以平均延误时间最小为目标,配时周期处于可行域内为约束条件的优化模型。本文通过遗传算法求解模型,以一定概率接受可行域外的种群,然后让种群慢慢逼近到可行域范围内,再让种群在可行域内迭代。对于迭代到可行域之外的群体降低它的适应度,使得最终结果对既收敛到最优解又满足约束条件。本文以车辆延误率作为评价指标,其仿真结果说明用该方法得到的信号灯配时方案比原有定时方案更有效。 展开更多
关键词 遗传算法 延误率 约束条件 相位 流量饱和度 配时周期
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Pore-scale simulation of gas-water flow in low permeability gas reservoirs 被引量:2
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作者 曹廷宽 段永刚 +2 位作者 郁伯铭 方全堂 王容 《Journal of Central South University》 SCIE EI CAS 2014年第7期2793-2800,共8页
A novel method was developed to establish a realistic three dimensional(3D) network model representing pore space in low permeability sandstone.Digital core of rock sample was established by the combination of micro-C... A novel method was developed to establish a realistic three dimensional(3D) network model representing pore space in low permeability sandstone.Digital core of rock sample was established by the combination of micro-CT scanning and image processing,then 3D pore-throat network model was extracted from the digital core through analyzing pore space topology,calculating pore-throat parameters and simplifying the shapes of pores and throats.The good agreements between predicted and measured porosity and absolute permeability verified the validity of this new network model.Gas-water flow mechanism was studied by using pore-scale simulations,and the influence of pore structure parameters,including coordination number,aspect ratio and shape factor,on gas-water flow,was investigated.The present simulation results show that with the increment of coordination number,gas flow ability in network improves and the effect of invading water on blocking gas flow weakens.The smaller the aspect ratio is,the stronger the anisotropy of the network is,resulting in the increase of seepage resistance.It is found that the shape factor mainly affects the end points in relative permeability curves,and for a highly irregular pore or throat with a small shape factor,the irreducible water saturation(Swi) and residual gas saturation(Sgr) are relatively high. 展开更多
关键词 low permeability sandstone X-ray computed tomography pore-scale modeling pore structure gas-water flow
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Cellular automation model for analyzing capacity of branch road section 被引量:2
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作者 王英姿 龙东方 史峰 《Journal of Central South University》 SCIE EI CAS 2011年第5期1744-1749,共6页
In order to reduce the traffic pressure of urban arterial road with the rational utilization of the branch road,the vehicle meeting behavior on the branch road without divided lane was described,and the cellular autom... In order to reduce the traffic pressure of urban arterial road with the rational utilization of the branch road,the vehicle meeting behavior on the branch road without divided lane was described,and the cellular automation (CA) model was put forward by introducing meeting behavior to reflect the relation between safe meeting speed and road width.The numerical simulation results depict several relation curves between road section capacity,speed and road width under different directional distributions of traffic flow,as well as the curves between the major and minor direction saturation flow,speed and road width.These relation characteristics indicate that except the one-way road section capacity and speed remaining unchanged,other road section capacities and speeds under different directional distributions increase with the increase of road width.On narrow road,the two-way traffic capacity and speed are less than those of one-way traffic;on wide road,the two-way traffic capacity doubles that of one-way traffic,but their speeds are almost the same.As the directional distribution moves to an even distribution of 50/50,the major direction saturation flows and speeds as well as the minor direction speeds tend to decease,while the minor direction saturation flow tends to increase. 展开更多
关键词 urban traffic road section capacity safe meeting speed cellular automation model
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三车道高速公路事发路段交通控制等级划分标准研究 被引量:1
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作者 孙明玲 《公路》 北大核心 2019年第11期163-166,共4页
首先提出目前我国标准、应急预案中事件严重程度的判断标准仅适用于划定事件本身,对严重程度判断具有主观性,不能客观科学地预估事故对道路交通产生的影响。本文首次提出事发路段交通控制等级的概念,以事件占用车道数、车道关闭时间和... 首先提出目前我国标准、应急预案中事件严重程度的判断标准仅适用于划定事件本身,对严重程度判断具有主观性,不能客观科学地预估事故对道路交通产生的影响。本文首次提出事发路段交通控制等级的概念,以事件占用车道数、车道关闭时间和流量饱和度三项指标来判断事发路段的交通控制等级。以三车道高速公路为研究对象,利用VISSIM仿真软件模拟,得出不同条件下事发路段的最大排队长度和消散时间,初步提出三车道高速公路事发路段交通控制等级划分标准及相应的控制措施。 展开更多
关键词 交通控制分级 三车道高速公路 划分标准 流量饱和度 仿真
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Experimental Investigation on Heat Transfer Coefficient during Upward Flow Condensation of R410A in Vertical Smooth Tubes 被引量:4
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作者 YANG Yunxiao JIA Li 《Journal of Thermal Science》 SCIE EI CAS CSCD 2015年第2期155-163,共9页
This paper presents an experimental investigation on condensation of R410 A upward flow in vertical tubes with the same inner diameter of 8.02 mm and different lengths of 300 mm, 400 mm, 500 mm and 600 mm. Condensatio... This paper presents an experimental investigation on condensation of R410 A upward flow in vertical tubes with the same inner diameter of 8.02 mm and different lengths of 300 mm, 400 mm, 500 mm and 600 mm. Condensation experiments were performed at mass fluxes of 103-490 kg m-2s-1. The saturation temperatures of experimental condition were 31℃, 38℃and 48℃, alternatively. The average vapor quality in the test section is between 0.91 and 0.98. The effects of tube length, mass flux and condensation temperature on condensation were discussed. Four correlations used for the upward flow condensation were compared with the experimental data obtained from various experimental conditions. A modified correlation was proposed within a ±15% deviation range. 展开更多
关键词 CONDENSATION R410A Flow upward Heat transfer coefficient REFRIGERANT
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