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141.
142.
A new kind of nano-rod shaped polycarboxylic acid slump-retaining agent was synthesized. Transmission electron microscope (TEM) experiment showed that the nano-rod was bound together as macromolecular aggregates in solution. Application performance studying suggested that this kind nano-sized polymer material had excellently plasticity-retaining performance in cement-based materials and could improve endurance performance of hardened cement-based materials distinctly. The concrete with an initial slump of 2?C9 cm could achieve 3 h plasticity-retaining performance with the help of this kind nano-rod. The product had extremely wide application value in the market. 相似文献
143.
利用多媒体信息服务技术(MMS),开发了一套架构成本低、具有劝告教育功能、保证处罚告知到达率的移动抄牌系统。通过试用,该系统能对违法停车行为区别处理、彩信告知到达率高、实时性好、减轻了交巡警内业整理的工作量,具有良好的推广前景。 相似文献
144.
A numerical method is developed to investigate the dynamic response of cable-seabed interaction in this paper. The motion of cable is described by the Lumped Parameter Method, while the seabed, unlike the prevailing simplified model of elastic foundation, is modeled as an irregular continuous rigid surface with rebound and friction existing, and the forces exerted by the seabed consist of normal counterforce and isotropic tangential Coulomb friction resistance. To describe the detailed dynamic response, two coefficients are introduced by analogy with the theory of rigid body collision with friction. The cable-seabed kinematic and dynamic contact conditions are formulated subsequently, and are used to incorporate the seabed effect into the cable dynamics to produce a set of ordinary differential governing equations. In this paper, we employ 4th order Runge-Kutta method to solve these equations. Several simulation cases are presented to illustrate the seabed effect. The results show that friction and impact have a prominent influence on the statics and dynamics of the cable. 相似文献
145.
Ship maneuverability, in the field of ship engineering, is often predicted by maneuvering motion group MMG) mathematical model. Then it is necessary to determine hydrodynamic coefficients and interaction force coefficients of the model. Based on the data of free running model test, the problem for obtaining these coefficients is called inverse one. For the inverse problem, ill-oposedness is inherent, nonlinearity and great computation happen,and the computation is also insensitive, unstable and time-consuming. In the paper, a regnlarization method is introduced to solve ill-posed problem and genetic algorithm is used for nonlinear motion of ship maneuvering. In addition, the immunity is applied to solve the prematurity, to promote the global searching ability and to increase the converging speed. The combination of regnlarization method and immune genetic algorithm(RIGA) applied in MMG mathematical model, showed rapid converging speed and good stability. 相似文献
146.
A study of maneuvering control for an air cushion vehicle based on back propagation neural network 总被引:1,自引:0,他引:1
A back propagation (BP) neural network mathematical model was established to investigate the maneuvering control of an air cushion vehicle (ACV). The calculation was based on four-freedom-degree model experiments of hydrodynamics and aerodynamics. It is necessary for the ACV to control the velocity and the yaw rate as well as the velocity angle at the same time. The yaw rate and the velocity angle must be controlled correspondingly because of the whipping, which is a special characteristic for the ACV. The calculation results show that it is an efficient way for the ACV's maneuvering control by using a BP neural network to adjust PID parameters online. 相似文献
147.
<正>"里程碑",对于交通行业从业者来说,不会是陌生的字眼。它首先用来定义设于道路边、用以指示公路里程的标志,其次还用来比喻在发展历程中具有重要意义的标志性事件。广西壮族自治区交通规划勘察设计研究院下属智能交通设计分院(以下简称"智能分院"),已经走过了十年的风雨坎坷路,站在"成立十周年"的里程碑旁回顾与眺望,引人深思,令人感怀。十年上下求索、十年苦心经营,三千多个日夜的艰苦奋斗,浸透了智能分院全体员工的辛勤汗水,也从一个侧面见证着广西壮族自治区交通规划勘察设计研究院推进转型升级、实现变革与超越的企业发展之路。 相似文献
148.
以南京机场二通道秦淮新河桥工程为背景,建立钢混组合的混合连续梁精细化有限元模型,分析钢混结合段在各种荷载工况下的局部应力分布规律以及荷载在结合段内的传递路径。研究结果表明:受较大预应力的影响,结合段混凝土纵向保持受压状态,同时产生较大的横向剥裂应力;轴力在结合段分别通过前、后承压板和剪力连接件3种路径进行传递,后承压板的贡献最大;剪力连接件的传力效率不均匀,后承压板附近及前承压板之后的剪力连接件作用较大。 相似文献
149.
由无锡市无锡县电视接收器厂生产的全频道86—8型彩色黑白兼容室外电视天线,7月底通过部级技术鉴定。这种天线采用电抗互补原理,拓宽电视接收频道,其接收灵敏度高,图像清晰、稳定. 相似文献