基于时频分析的裂纹转子碰摩故障特征研究     

陶海亮  左志涛  高庆  谭春青 《贵州气象》2013,(4):520-528

为研究转子系统耦合故障特性,采用有限元方法建立了含有横向裂纹、转静碰摩的非线性转子动力学模型。首先研究了不同转速下裂纹、碰摩单一故障下转子系统的振动响应,其次研究了两种故障耦合情况下系统的振动响应特征。采用波形图、FFT谱图、瞬时频率和Hilbert-Huang时频谱(HHS)相结合的方法对故障转子振动信号进行了分析。分析结果表明:运用多种时频分析相结合的方法可以较为全面地了解转子的故障特征,裂纹转子在1/5、1/3临界转速时会发生较为明显的5X、3X谐波,且裂纹的产生会导致响应幅值增大,从而引起更为严重的碰摩。   相似文献   

农田小气候自动观测系统效能评估     

杨爱萍  杜筱玲  郭瑞鸽  刘文英 《气象科技》2013,41(2):278-281

介绍了架设于稻田的农田小气候自动观测系统,并采用气象站数据与该系统采集的气象数据进行对比,分析该系统的实用性,且构建数据到报率、数据可靠率等指标对系统稳定性和可靠性进行评估.结果表明:该系统可为农业防灾减灾提供高精度的农田小气候信息,实用性强;数据到报率达94.5％以上,系统运行稳定;数据格式错误和数据异常时次少,数据可靠率达85.2％以上;雷电灾害是影响系统稳定性、可靠性最主要的因素.农业气象自动化观测系统总体效能较好,在农业气象研究和服务中具有明显优势.  相似文献   

陆面过程模型对下垫面参数动态变化的敏感性分析   总被引：4，自引：0，他引：4  

蔡福  周广胜  李荣平  明惠青 《地球科学进展》2011,26(3):300-310

利用2006年锦州玉米农田生态系统野外观测站动态连续的通量、气象及生物因子观测数据,分析了BATSl e陆面模型对动态的粗糙度(Z0)、叶面积指数(LAI)、植被履盖度(FVEG)及反照率(α)变化的敏感性.结果表明:Z0的动态变化对表层土壤温度(SST)和感热(SH)的模拟有一定影响,主要发生在玉米农田从裸土向有植被...  相似文献   

SH波作用下岩质边坡响应规律的解析探讨     

周剑 《工程地质学报》2011,19(4):570-576

基于弹性力学理论,推导了弹性波动方程,并给出了位移势函数的表达式.根据应力波传播理论建立了边坡中应力波传播模型,以SH波为例详细说明了边坡中不同部位的应力波叠加情况.将边坡的坡面和坡顶自由面解耦为2个相互独立的自由面,分别分析了2个自由面附近应力波场的叠加,并据此研究了边坡中波函数幅值变化情况,得到了边坡水平向动力放大...  相似文献   

城市地下管线空间数据更新研究     

刘艳丽 《城市地质》2011,6(2):39-41

本文结合城市地下管线管理现状,研究了目前城市地下管线数据更新维护中存在的问题,探讨了城市地下管线空间数据更新原则,必要条件和更新方法。  相似文献   

Design and reliability analysis of DP-3 dynamic positioning control architecture     

王芳  万磊  姜大鹏  徐玉如 《中国海洋工程》2011,25(4):709-720

As the exploration and exploitation of oil and gas proliferate throughout deepwater area,the requirements on the reliability of dynamic positioning system become increasingly stringent.The control objective ensuring safety operation at deep water will not be met by a single controller for dynamic positioning.In order to increase the availability and reliability of dynamic positioning control system,the triple redundancy hardware and software control architectures were designed and developed according to the safe specifications of DP-3 classification notation for dynamically positioned ships and rigs.The hardware redundant configuration takes the form of triple-redundant hot standby configuration including three identical operator stations and three real-time control computers which connect each other through dual networks.The function of motion control and redundancy management of control computers were implemented by software on the real-time operating system VxWorks.The software realization of task loose synchronization,majority voting and fault detection were presented in details.A hierarchical software architecture was planed during the development of software,consisting of application layer,real-time layer and physical layer.The behavior of the DP-3 dynamic positioning control system was modeled by a Markov model to analyze its reliability.The effects of variation in parameters on the reliability measures were investigated.The time domain dynamic simulation was carried out on a deepwater drilling rig to prove the feasibility of the proposed control architecture.  相似文献   

Sea trials and application of a numerical method for the analysis of the ocean current displacement phenomena of demersal longlines   总被引：2，自引：0，他引：2  

Jihoon Lee  Ludvig Karlsen 《Ocean Engineering》2011,38(16):1744-1754

In this study, a numerical method for the analysis of the sinking speed of demersal longlines was developed to obtain further insight into the ocean current displacement of demersal longlines. The sinking speed is one of the main factors affecting the extent of current displacement, which is the horizontal movement of longlines due to ocean currents.To improve the accuracy of the model, bait properties were investigated in a flume tank, and the resistance coefficients of full scale models based on different bait shapes, sizes and orientations were established. The numerical method was verified by full scale experiments conducted in the sea.In the theoretical analysis, the sinking speed of a Norwegian commercial longline was calculated. Current-related data of a common longlining area in Norway were obtained from the Acoustic Doppler Current Profiler (ADCP) and were used to calculate the ocean current displacement of a demersal longline. The results show the ocean current displacement of longlines, and make to expect a decrease in the fishing efficiency.  相似文献   

Computations of self-propulsion free to sink and trim and of motions in head waves of the KRISO Container Ship (KCS) model   总被引：2，自引：0，他引：2  

Pablo M. Carrica  Huiping Fu  Frederick Stern 《Applied Ocean Research》2011,33(4):309-320

Two computations of the KCS model with motions are presented. Self-propulsion in model scale free to sink and trim are studied with the rotating discretized propeller from the Hamburg Model Basin (HSVA) at Fr = 0.26. This case is particularly complex to simulate due to the close proximity of the propeller to the rudder. The second case involves pitch and heave in regular head waves. Computations were performed with CFDShip-Iowa version 4.5, a RANS/DES CFD code designed for ship hydrodynamics. The self-propulsion computations were carried out following the procedure described in Carrica et al. [1], in which a speed controller is used to find the propeller rotational speed that results in the specified ship velocity. The rate of revolutions n, sinkage, trim, thrust and torque coefficients K_T, K_Q and resistance coefficient CT_(SP) are thus obtained. Comparisons between CFD and EFD show that the rate of revolutions n, thrust and torque coefficients K_T and K_Q have higher prediction accuracies than sinkage and trim. For the simulation of pitch and heave in head waves, the geometry includes KCS hull and rudder under three conditions with two Froude numbers and three wave length and amplitude combinations. 0th and 1st harmonic amplitudes and 1st harmonic phase are computed for total resistance coefficient C_T, heave motion z and pitch angle θ. Comparisons between CFD and EFD show that pitch and heave are much better predicted than the resistance. In both cases comparisons with simulations by other authors presented at the G2010 CFD Workshop [2] using different CFD methodologies are included.  相似文献   

大学英语成绩测试的信度与效度关系探析     

陈哲 《广东海洋大学学报》2011,31(2):98-101

信度和效度是第二代语言测试体系提出的两个不同的概念,处理好两者之间的关系,有利于教师正确把握大学英语测试的科学性。以第二代语言测试体系理论为基础,利用Gitest数据统计软件,进行一项针对大学英语成绩测试的信度与效度分析时发现,测试信度的实现以效度为代价,严重影响了测试的质量。而信度与效度的平衡关键在于测试目的的明确和测试方式的灵活处理。  相似文献   

Non-adiabatic State and Heat Energy Release in the Interior of the Earth     

Chen Dianyou 《东北亚地学研究》2000,(1)

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