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  • 恒压供水泵站系统的设计和开发

    介绍了变频调速技术的节能原理,阐述了基于PLC和变频器控制的恒压供水特点,完成了一台变频器控制四台水泵实现恒压供水的具体要求,设计了硬件控制回路和软件编程方法.实际运行证明,变频恒压供水系统控制简单、可靠性高、保护功能完善、节能效果明显.
    武慧平,朱铭强,张盼盼,王富刚,亢福仁,卜耀军 - 干旱地区农业研究
    文章来源: 万方数据
  • 河北省井灌区小型农田水利项目监测评价探讨

    介绍了小型农田水利项目监测评价的内容、监测方法与手段,监测内容包括毛灌水量,净灌水量,地下水水位情况,作物产量情况,灌溉管理等.用调查实测和理论分析相结合的方法,以冀州市2010年度小型农田水利项目监测评价为例对灌溉水利用率、水分生产率、增产增收等评价指标进行合理性分析,从而监测出项目实施后在节水和用水效益等方面达到的实际效果,以及对实施建设小型农田水利工程起到重要意义.
    李静,连少伟,谢磊 - 南水北调与水利科技
    文章来源: 万方数据
  • 基于信息距离的仓库管理系统易用性测度研究

    系统易用性是影响系统军事效益的重要因素,是系统设计时要考虑的一项重要的指标.分析了易用性、功能性以及用户界面关系,采用信息状态转移距离即信息距离理论,研究系统等概率选择和信息状态串联结构时,单路径单目标和单路径多目标组合的易用性信息距离直接测度方法.以车辆器材仓库管理系统的实例,测算系统主路径信息距离和系统平均信息距离等参数,并给出系统易用性评估结论,以供参考.
    董翔英,任聪,蔡志强 - 物流技术
    文章来源: 万方数据
  • The existing research of steering efficiency mainly focuses on the mechanism efficiency of steering system,aiming at designing and optimizing the mechanism of steering system.In the development of assist steering system especially the evaluation of its comfort,the steering efficiency of driver physiological output usually are not considered,because this physiological output is difficult to measure or to estimate,and the objective evaluation of steering comfort therefore cannot be conducted with movement efficiency perspective.In order to take a further step to the objective evaluation of steering comfort,an estimating method for the steering efficiency of the driver was developed based on the research of the relationship between the steering force and muscle activity.First,the steering forces in the steering wheel plane and the electromyography(EMG)signals of the primary muscles were measured.These primary muscles are the muscles in shoulder and upper arm which mainly produced the steering torque,and their functions in steering maneuver were identified previously.Next,based on the multiple regressions of the steering force and EMG signals,both the effective steering force and the total force capacity of driver in steering maneuver were calculated.Finally,the steering efficiency of driver was estimated by means of the estimated effective force and the total force capacity,which represented the information of driver physiological output of the primary muscles.This research develops a novel estimating method for driver steering efficiency of driver physiological output,including the estimation of both steering force and the force capacity of primary muscles with EMG signals,and will benefit to evaluate the steering comfort with an objective perspective.
     - 中国机械工程学报
    文章来源: 万方数据
  • Quadruped robots consume a lot of energy,which is one of the factors restricting their application.Energy efficiency is one of the key evaluating indicators for walking robots.The relationship between energy and elastic elements of walking robots have been studied,but different walking gait patterns and contact status have important influences on locomotion energy efficiency,and the energy efficiency considering the foot-end trajectory has not been reported.Therefore,the energy consumption and energy efficiency of quadruped robot with trot gait and combined cycloid foot trajectory are studied.The forward and inverse kinematics of quadruped robot is derived.The combined cycloid function is proposed to generate horizontal and vertical foot trajectory respectively,which can ensure the acceleration curve of the foot-end smoother and more successive,and reduce the contact force between feet and environment.Because of the variable topology mechanism characteristic of quadruped robot,the leg state is divided into three different phases which are swing phase,transition phase and stance phase during one trot gait cycle.The non-continuous variable constraint between feet and environment of quadruped robot is studied.The dynamic model of quadruped robot is derived considering the variable topology mechanism characteristic,the periodic contact and elastic elements of the robot.The total energy consumption of walking robot during one gait cycle is analyzed based on the dynamic model.The specific resistance is used to evaluate energy efficiency of quadruped robot.The calculation results show the relationships between specific resistance and gait parameters,which can be used to determine the reasonable gait parameters.
     - 中国机械工程学报
    文章来源: 万方数据
  • Micro-gas turbine engine(MTE) rotor is an important indicator of its property, therefore, the manufacturing technology of the microminiature rotor has become a hot area of research at home and abroad. At present, the main manufacturing technologies of the MTE rotor are directed forming fabrication technologies. However, these technologies have a series of problems, such as complex processing technology high manufacturing cost, and low processing efficiency, and so on. This paper takes advantage of micro electric discharge machining(micro-EDM) in the field of microminiature molds manufacturing, organizes many processing technologies of micro-EDM reasonably to improve processing accuracy, presents an integrated micro-EDM technology and its process flow to fabricate MTE rotor die, and conducts a series of experiments to verify efficiency of this integrated micro-EDM. The experiments results show that the MTE rotor die has sharp outline and ensure the good consistency of MTE rotor blades. Meanwhile, the MTE rotor die is applied to micro extrusion equipment, and technologies of micro-EDM and micro forming machining are combined based on the idea of the molds manufacturing, so the MTE rotor with higher aspect ratio and better consistency of blades can be manufactured efficiently. This research presents an integrated micro-EDM technology and its process flow, which promotes the practical process of MTE effectively.
     - 中国机械工程学报
    文章来源: 万方数据
  • The large and complex structures are divided into hundreds of thousands or millions degrees of freedom(DOF) when they are calculated which will spend a lot of time and the efficiency will be extremely low. The classical component modal synthesis method(CMSM) are used extensively, but for many structures in the engineering of high-rise buildings, aerospace systemic engineerings, marine oil platforms etc, a large amount of calculation is still needed. An improved hybrid interface substructural component modal synthesis method(HISCMSM) is proposed. The parametric model of the mistuned blisk is built by the improved HISCMSM. The double coordinating conditions of the displacement and the force are introduced to ensure the computational accuracy. Compared with the overall structure finite element model method(FEMM), the computational time is shortened by 23.86%–31.56% and the modal deviation is 0.002%–0.157% which meets the requirement of the computational accuracy. It is faster 4.46%–10.57% than the classical HISCMSM. So the improved HISCMSM is better than the classical HISCMSM and the overall structure FEMM. Meanwhile, the frequency and the modal shape are researched, considering the factors including rotational speed, gas temperature and geometry size. The strong localization phenomenon of the modal shape's the maximum displacement and the maximum stress is observed in the second frequency band and it is the most sensitive in the frequency veering. But the localization phenomenon is relatively weak in 1st and the 3d frequency band. The localization of the modal shape is more serious under the condition of the geometric dimensioning mistuned. An improved HISCMSM is proposed, the computational efficiency of the mistuned blisk can be increased observably by this method.
    BAI Bin,BAI Guangchen,LI Chao - 中国机械工程学报(英文版)
    文章来源: 万方数据
  • 黄骅市水资源形势及开发利用分析

    黄骅市地处河北省东部平原,地表水资源利用能力低,浅层地下水水质差,长期依赖于开采深层地下水,造成地下水环境的破坏.通过准确把握黄骅市水资源特点,合理利用地表水,最大限度利用外来水,控制利用当地地下水,保证经济社会的可持续发展.
    孙淑珍 - 南水北调与水利科技
    文章来源: 万方数据
  • 河北省引黄输水水质变化特征分析

    河北省引黄输水工程是解决河北省水资源危机的有效措施.从1993年开始的引黄输水工程,为缓解河北省水资源紧张发挥了重要作用.通过对引黄输水水质监测结果分析,通过对8次引黄输水水质评价,在对所监测的项目中.有3次输水没有超标现象,有3次污染物的超标倍数小于或等于1,有2次超标倍数在1.2~2.8之间.从输水水质主要污染物分析,主要污染物为氨氮、挥发酚、总磷、总锰、总镉.根据对黄河水源水质资料分析,氮类污染和金属类污染主要受缓和黄河水源的影响,挥发酚、总磷污染主要受河道环境的污染.通过对引黄调水水质评价,受黄河水源和沿途河道的影响,引黄调水水质存在较大的不确定性.因此应加强对引黄调水水质的监测,为用水部门及时提供调水水质信息,以便制宰相席的用水方案.
    张家兴,张学知 - 南水北调与水利科技
    文章来源: 万方数据
  • Now the optimization strategies for power distribution are researched widely,and most of them are aiming to the optimal fuel economy and the driving cycle must be preknown.Thus if the actual driving condition deviates from the scheduled driving cycle,the effect of optimal results will be declined greatly.Therefore,the instantaneous optimization strategy carried out on-line is studied in this paper.The power split path and the transmission efficiency are analyzed based on a special power-split scheme and the efficiency models of the power transmitting components are established.The synthetical efficiency optimization model is established for enhancing the transmission efficiency and the fuel economy.The identification of the synthetical efficiency as the optimization objective and the constrain group are discussed emphatically.The optimization is calculated by the adaptive simulated annealing(ASA)algorithm and realized on-line by the radial basis function(RBF)-based similar models.The optimization for power distribution of the hybrid vehicle in an actual driving condition is carried out and the road test results are presented.The test results indicate that the synthetical efficiency optimization method can enhance the transmission efficiency and the fuel economy of the power-split hybrid electric vehicle(HEV)observably.Compared to the rules-based strategy the optimization strategy is optimal and achieves the approximate global optimization solution for the power distribution.The synthetical efficiency optimization solved by ASA algorithm can give attentions to both optimization quality and calculation efficiency,thus it has good application foreground for the power distribution of power-split HEV.
     - 中国机械工程学报
    文章来源: 万方数据
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