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Search Results: 1 - 10 of 23714 matches for " 卢紫旺 "
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机械变速器换档的接合过程建模及特性分析
Modeling and characteristic analysis of engaging process during gear shifting of mechanical transmissions

陈红旭,,王立军,田光宇
- , 2018,
Abstract: 接合套和接合齿圈的接合过程是影响机械变速器换档品质的关键阶段。针对在接合过程中,当接合套和接合齿圈在齿端倒角处接触时碰撞发生,其相对速度会发生突变,相应的耦合关系及动力学方程也会发生改变的现象,为了得到机械变速器整个接合过程的精确数学模型和特性,运用多体动力学理论和混杂系统方法建立了描述接合过程的混杂自动机模型。在该模型中,用3个微分方程组描述接合过程中接合套和接合齿圈在不同耦合关系下的动力学特性;引入泊松恢复系数,建立了4个差分方程组描述碰撞过程接合齿圈转速、接合套轴向运动速度和转速产生的突变。基于该混杂自动机模型,在MATLAB环境下进行了仿真分析,得到了接合过程中接合套和接合齿圈的轨迹、接合时间和最大冲击,分析了换档力、接合套相对接合齿圈的初始转速和位置对接合性能(时间和最大冲击)的影响。研究结果表明:接合套和接合齿圈的相对位置对接合时间和冲击有显著影响;当接合套和接合齿圈的转速差在一定范围内时,接合时间较短,过大的转速差则会使接合时间呈指数上升;接合套和接合齿圈的转速差越大,冲击越大;增大换档力可缩短接合时间,但会增大冲击。在设计机械式自动变速器的控制系统时,应根据机械变速器换档过程的特性,选取最佳的换档力、相对转速、相对位置作为控制参数,进而缩短动力中断时间,减小换档冲击。
The engaging process of engaging sleeve and clutch gear is the key phase influencing the gear shifting performance of mechanical transmissions. During an engaging process, collision occurred when engaging sleeve and clutch gear contacted at the end of the tooth chamfer, their relative speed suddenly changed, and their coupling relationship and dynamic equations also changed. In order to obtain an accurate mathematical model and characteristics of the engaging process of mechanical transmission, a hybrid automaton model was built to describe the engaging process through multi-body dynamics theory and hybrid system methodology. In this model, three sets of differential equations were built to describe the dynamic characteristics of engaging sleeve and clutch gear under different coupling relationships during an engaging process. Poisson recovery coefficient was introduced to build four sets of difference equations to describe the rotational speed of clutch gear, the axial movement speed of engaging sleeve and the sudden change of rotational speed during the collision process. Based on the hybrid automaton model, simulation analysis was carried out in the MATLAB environment. The trajectories, the engaging duration and the maximum impact of engaging sleeve and clutch gear during their engaging process were obtained. The effects of the shifting force and the initial rotational speed and position of engaging sleeve relative to clutch gear on engaging performance were analyzed. The results show that the relative position of engaging sleeve and clutch gear has significant effect on the engaging duration and the maximum impact. If the rotational speed difference of engaging sleeve and clutch gear is within limit, the engaging duration is relatively short, and a big rotational speed difference will cause an exponential rise of engaging duration, a bigger rotational speed difference of engaging sleeve and clutch gear will cause a bigger engaging impact. When increasing the shifting force, the engaging duration will
边界约束二次规划问题的分解方法
战杰,
计算数学 , 1999,
Abstract:
气相色谱专家系统柱推荐软件之二——判断用GC分析是否满足充分条件的软件
许国,佩章
色谱 , 1990,
Abstract: ]本文报道了色谱专家系统中判断样品是否满足GC分析充分条件的软件。依据是:对满足必要条件的样品,除了碳数间峰容量不足及作用距离十分相近的某些位置异构体分不开外,均可采用GC,通过调节选择性获得分离。采用产生式的知识表达,并用正向推理,在IBMPC机上实现了判断样品是否满足GC分析充分条件的功
专家系统柱推荐软件之一——判断用气相色谱分析是否满足必要条件的软件
许国,佩章
色谱 , 1990,
Abstract: 本文报道了色谱专家系统中判断样品是否满足气相色谱(GC)分析必要条件的软件。依据是:能以合适k′(0.2
气相色谱柱子和固定相的选择
许国,佩章
色谱 , 1991,
Abstract: 本文从色谱保留方程lnk′=(B_1α_A+B_2μ_A~2+B_3+B_4)/RT+V_A~1/V_B~1-lnβ出发,考虑溶质-溶剂间的相互作用力、从理论和实际两方面,探讨了同系物、结构异构体、几何异构体、旋光异构体及沸点在25℃以下的气体等采用气相色谱分析时柱子和固定相的选择。
气相色谱专家系统柱推荐软件之二——判断用GC分析是否满足充分条件的软件
许国,佩章
色谱 , 1990,
Abstract: 本文报道了色谱专家系统中判断样品是否满足GC分析充分条件的软件。依据是:对满足必要条件的样品,除了碳数间峰容量不足及作用距离十分相近的某些位置异构体分不开外,均可采用GC,通过调节选择性获得分离。采用产生式的知识表达,并用正向推理,在IBM PC机上实现了判断样品是否满足GC分析充分条件的功
专家系统柱推荐软件之一——判断用气相色谱分析是否满足必要条件的软件
许国,佩章
色谱 , 1990,
Abstract: ]本文报道了色谱专家系统中判断样品是否满足气相色谱(GC)分析必要条件的软件,依据是:能以合适k'(0.2k'20)流出且在柱温孪下稳定的样品可采用GC法分析。而k'值通过结构和保留值间的关系式来计算。作者使用框架结构的知识表达法,用SchcmeLisp语言,在IBMPC机上实现了这一专家判断功能。采用本文列出的知识库和源程序,可对含C、H、Q、N、Cl、Br、I、P、S、Si等元素的化合物能否采用气相色谱进行判断。
慎言科学技术一体化
,李光
科技进步与对策 , 2006,
Abstract: 在大科学和高技术时代,针对科学技术化、技术科学化的发展趋势,人们提出了“科学技术一体化”,这种提法对于认识新时期科学技术发展的新特点、新趋势,无疑有着非常积极的意义。但是,如果过分强调科学技术一体化,主张彻底的一体化必然导致基础科学发展面临“功利化”的灾难,势必导致科学知识成果被保护,影响科学自身的发展,甚至会形成“科学霸权”。在分析科学技术一体化过程中两对矛盾(即科学技术彻底一体化羁绊)的基础上提出倡导科学技术一体化必须谨慎,应该警惕过分强调一体化以致忽视科学与技术之区分的倾向。科学技术一体化
中国乡村共同体的历史变迁与现实走向
Historical Change and Development Trend of Chinese Rural Community

许远,,
- , 2015,
Abstract: 针对传统乡村社区的性质与特征,学界先后提出过“村落共同体”“宗族共同体”以及“市场共同体”几种不同的界说。虽然这些观点也注意到村落的开放性尤其是“基层市场共同体”的联系,但主要是采取一种整体性和静态的视角,将乡村视作一种相对封闭和自治体。晚清以降,随着国家政权建设的启动,域外因素日益介入乡村治理,加剧了乡村官僚化和行政化趋势。在国家整合及一体化建设过程中,人们试图通过经济、政治手段改造乡村社区,在部分实现国家治理目标的同时,在实践中也造成一定程度的危害及后果。新时期农村社区建设应走“服务嵌入”之路,通过"服务下乡"重塑居民对社区的认同和归属感,构建"管理有序、服务完善、文明祥和"的社会生活共同体。
For the nature and characteristics of Chinese traditional rural community, scholars have proposed several different definitions such as “village community” “clan community” and “market community”. Although these views above have recognized the openness of the village, especially the link among different “market communities”, they mainly take a holistic and static perspective which regard the village as a relatively closed and autonomous body. From the late Qing Dynasty, with the start of construction of State Power, external forces increasingly involved in rural governance, which exacerbated the bureaucratic and administrative trend of the countryside. Afterwards, in the process of State integration, people tried to transform rural community through economic and political means, partly achieved the goal of State governance whilst caused some disasters in practice. Therefore, the construction of rural community in a new era should follow the “service embedded”road, to revitalize the residents’ identity to rural community and rebuild a social life community characterized by “orderly management, perfect service, civilized and harmonious environment”.
暗霉素的快原子轰击(FAB)质谱
方一苇,,林桂坚
化学学报 , 1985,
Abstract:
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