-
糯扎渡水电站溢洪道深化设计
糯扎渡水电站地处狭谷地区,泄洪最大水头182 m,溢洪道最大泄洪流量31318 m3/s,泄洪功率达55 860MW,其规模为目前国内最大,泄洪消能问题十分突出.为此,在可研阶段对泄洪建筑物布置进行了多方案比选研究,在招标阶段进行了深化研究,结合整体水工模型试验及溢洪道单体、掺气减蚀、护岸不护底、泄洪雾化等专题研究,设计了适合该工程的大型岸边溢洪道,在溢洪道挑流鼻坎下游设置消力塘,有效解决了消能问题.杨再宏,顾亚敏,刘兴宁,孙怀昆 - 水力发电文章来源: 万方数据 -
日本节能理念和制度创意对我国的启示
"十二五"时期我国节能工作面临着更加复杂的形势和严峻的挑战,需要在以往工作基础上有所创新和突破.日本是全球能源效率最高的国家之一,节能取得卓越成绩不仅依靠对技术的不懈追求,更依靠对节能更加深入的理解和政策上的大胆尝试.通过将节能融入经济发展战略、"以人为本"的管理手段以及用更加系统整体的眼光重新看待节能技术和产品,加上能源管理师、领跑者等制度上的创新,日本一直保持着全球节能引领者地位.本文简要地回顾和总结了日本近年来节能理念和制度方面的创新,并结合我国"十一五"以来节能工作,提出了针对"十二五"节能工作的政策建议.符冠云,郁聪 - 中国能源文章来源: 万方数据 -
现代仓储管理技术在防汛物资储备管理中的应用
防汛物资的管理和运用效果直接影响防汛抢险工作的成果,合理运用、科学管理是保证防汛物资能最大限度发挥其救灾效用的基础.应用现代仓库管理技术,通过严把物资入库验收关、对人库物资进行登账、立卡、建档以及盘点与清查等各个环节管理物资,按照防汛物资要求维护保养物资,能够为防汛抢险提供根本保障.同时,对加快防汛物资管理现代化建设等方面提出建议.李恩慧,时启军,李月霞 - 南水北调与水利科技文章来源: 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
-
文安县城防洪圈工程建设设想
针对文安县现有防洪圈已不能满足经济社会发展的需要,特别是工业园区和产业集聚区的发展已经受到滞洪区产业政策的严重影响,重大项目的防洪影响评价和环境保护评价很难过关的问题.提出新的县城防洪圈工程建设设想,包括围堤堤线布置和堤型选择、堤顶路面建设、生态化建设、环城水系建设、城区排水建设等.在保证基本防洪功能基础上,从根本上解决滞洪问题,形成一个四面环水的相对独立的交通便利、环境优美、生态和谐的美丽城区.王敏 - 南水北调与水利科技文章来源: 万方数据 -
新国标GBl8613颁布后对中小型电机行业的影响
新国标(GBl8613)将在2012年内发布并正式开始实施,对新旧标准分别进行了介绍,具体分析了新国标颁布实施后,可能会给中小型电机行业带来的影响,企业应做好相应的技术准备.黄坚 - 电机与控制应用文章来源: 万方数据 -
178Hf长寿命同核异能态触发γ跃迁的理论探讨
近年来178Hfm2 31年的同核异能态被认为是用低能X射线触发使其释放储存能量的最合适候选者.为了探讨在178Hf中是否存在触发Kπ=16+同核异能态γ发射的门态,本工作首先用投影壳模型对178Hf的多准粒子态和集体激发态进行了研究,结果表明其它态位于距离16+同核异能态较远的地方.但当用包括γ自由度的组态限制(绝热阻塞)方法计算178Hf的多准粒子激发态时,结果显示有三个能级可能是16+同核异能态光退激的候选者,位能面计算的结果显示178Hf为轴对称硬核.王飞鹏,沈水法,阎玉鹏 - 核技术文章来源: 万方数据 -
The existing research of the acceleration control mainly focuses on an optimization of the velocity trajectory with respect to a criterion formulation that weights acceleration time and fuel consumption. The minimum-fuel acceleration problem in conventional vehicle has been solved by Pontryagin's maximum principle and dynamic programming algorithm, respectively. The acceleration control with minimum energy consumption for battery electric vehicle(EV) has not been reported. In this paper, the permanent magnet synchronous motor(PMSM) is controlled by the field oriented control(FOC) method and the electric drive system for the EV(including the PMSM, the inverter and the battery) is modeled to favor over a detailed consumption map. The analytical algorithm is proposed to analyze the optimal acceleration control and the optimal torque versus speed curve in the acceleration process is obtained. Considering the acceleration time, a penalty function is introduced to realize a fast vehicle speed tracking. The optimal acceleration control is also addressed with dynamic programming(DP). This method can solve the optimal acceleration problem with precise time constraint, but it consumes a large amount of computation time. The EV used in simulation and experiment is a four-wheel hub motor drive electric vehicle. The simulation and experimental results show that the required battery energy has little difference between the acceleration control solved by analytical algorithm and that solved by DP, and is greatly reduced comparing with the constant pedal opening acceleration. The proposed analytical and DP algorithms can minimize the energy consumption in EV's acceleration process and the analytical algorithm is easy to be implemented in real-time control.- 中国机械工程学报文章来源: 万方数据
-
Eddy current pulsed thermography(ECPT) is an emerging Non-destructive testing and evaluation(NDT & E) technique, which uses hybrid eddy current and thermography NDT & E techniques that enhances the detectability from their compensation. Currently, this technique is limited by the manual selection of proper contrast frames and the issue of improving the efficiency of defect detection of complex structure samples remains a challenge. In order to select a specific frame from transient thermal image sequences to maximize the contrast of thermal variation and defect pattern from complex structure samples, an energy driven approach to compute the coefficient energy of wavelet transform is proposed which has the potential of automatically selecting both optimal transient frame and spatial scale for defect detection using ECPT. According to analysis of the variation of different frequency component and the comparison study of the detection performance of different scale and wavelets, the frame at the end of heating phase is automatically selected as an optimal transient frame for defect detection. In addition, the detection capabilities of the complex structure samples can be enhanced through proper spatial scale and wavelet selection. The proposed method has successfully been applied to low speed impact damage detection of carbon fibre reinforced polymer(CFRP) composite as well as providing the guidance to improve the detectability of ECPT technique.- 中国机械工程学报文章来源: 万方数据
-
运用因次分析法比较中国能源通道
近年来,中国能源运输通道问题日益显现,以马六甲海峡及南海等区域最为突出.为解决我国能源通道安全受到严重制约的困局,利用因次分析法,依据评价指标体系建立的各项基本原则,针对出现的不同情况分别对传统运输通道与新路线做简要对比分析.在保证国内石油安全充足供应,尽可能降低物流成本的前提下,提出较为有效合理的对策和建议,对我国能源安全运输具有现实意义.刘传铎,王海灵 - 物流技术文章来源: 万方数据

