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压裂液强制返排及支撑剂回流模型研究 被引量:17
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作者 胡景宏 何顺利 +2 位作者 李勇明 邓燕 赵金洲 《西安石油大学学报(自然科学版)》 CAS 2008年第5期57-61,共5页
如何科学合理选择放喷油嘴尺寸,同时准确预测裂缝闭合时间,是压裂液强制返排的核心.根据支撑剂运移和压裂液强制返排机理,同时考虑支撑剂受力、压裂液二维滤失、压裂液压缩性和井筒摩阻,并结合物质平衡原理、岩石力学和流体力学的相关理... 如何科学合理选择放喷油嘴尺寸,同时准确预测裂缝闭合时间,是压裂液强制返排的核心.根据支撑剂运移和压裂液强制返排机理,同时考虑支撑剂受力、压裂液二维滤失、压裂液压缩性和井筒摩阻,并结合物质平衡原理、岩石力学和流体力学的相关理论,建立了裂缝闭合前后放喷油嘴尺寸选型的支撑剂运移及力学模型和裂缝强制闭合时间计算模型.采用建立的模型,不仅可使放喷油嘴尺寸定量化,同时在不需要冗长的压降数据情况下,就能确定裂缝强制闭合时间.经实例验证,本模型的计算结果稳定可靠,可用于实际分析. 展开更多
关键词 压裂液 强制返排 裂缝闭合 支撑剂回流 模拟模型
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城镇就业风险、环境、条件与外出务工农村劳动力的逆向回流 被引量:8
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作者 徐家鹏 《统计与信息论坛》 CSSCI 2013年第8期84-90,共7页
基于685份外出务工农村劳动力样本的问卷调查数据,建立有序Logistic回归模型,分析外出务工农村劳动力个人及家庭特征、就业能力、就业风险、就业环境及就业条件等对其逆向回流行为的影响。结果显示:外出务工农村劳动力年龄越大,身体素... 基于685份外出务工农村劳动力样本的问卷调查数据,建立有序Logistic回归模型,分析外出务工农村劳动力个人及家庭特征、就业能力、就业风险、就业环境及就业条件等对其逆向回流行为的影响。结果显示:外出务工农村劳动力年龄越大,身体素质和文化水平越低,务工单位拖欠工资与签订合同情况越差,城镇政策体制环境、经济环境和文化环境越差,理想工作的择业门槛越高,外出务工劳动力越倾向于彻底逆向回流。因此,为实现农村剩余劳动力的彻底转移,应积极发展城镇第二、第三产业,改善城镇就业环境,降低农村劳动力在城镇务工的就业风险,同时有效提高农村劳动力的健康水平和文化素质。 展开更多
关键词 外出务工农村劳动力 就业风险 就业环境 就业条件 逆向回流
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POWER FLOW ANALYSIS AND APPLICATION SIMULATION OF ELECTROMAGNETIC CONTINUOUSLY VARIABLE TRANSMISSION 被引量:3
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作者 LUO Yutao TAN Di MENG Fanzhen 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2008年第6期48-56,共9页
With the structure of two air gaps and two rotors, the electromagnetic continuously variable transmission(EMCVT) is a novel power-split continuously variable transmission(CVT). There are two kinds of power flowing... With the structure of two air gaps and two rotors, the electromagnetic continuously variable transmission(EMCVT) is a novel power-split continuously variable transmission(CVT). There are two kinds of power flowing through the EMCVT, one is mechanical power and the other is electric power. In the mean time, there are three power ports in the EMCVT, one is the outer rotor named mechanical power port and the other two are the inner rotor and the stator named electric power ports. The mechanical power port is connected to the driving wheels through the final gear and the electric ports are connected to the batteries through the transducers. The two kinds of power are coupled on the outer rotor of the EMCVT. The EMCVT can be equipped on the conventional vehicle being regarded as the CVT and it also can be equipped on the hybrid electric vehicle(HEV) as the multi-energy sources assembly. The power flows of these two kinds of applications are analysed. The back electromotive force(EMF) equations are illatively studied and so the dynamic mathematic model is theorized. In order to certify the feasibility of the above theories, three simulations are carried out in allusion to the above two kinds of mentioned applications of the EMCVT and a five speed automatic transmission(AT) vehicle. The simulation results illustrate that the efficiency of the EMCVT vehicles is higher than that of the AT vehicle owed to the optimized operation area of the engine. Hence the fuel consumption of the EMCVT vehicles is knock-down. 展开更多
关键词 Electromagnetic continuously variable transmission Power flow analysis back electromotive force application simulation
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