应用波型分析方法设计低波阻船型

本文应用波型分析方法设计低波阻船型。对设计的母型船进行波型测量,获取波幅函数。根据刘应中教授提出的等价薄船概念,用变态的Fourier变换方法求出等价薄船的修正函数。用互补主元法优化横剖面面积曲线,得到低兴波阻力船型。

基桩低应变检测的波型分析及桩身完整性判定

基桩工程在具体的施工中,存在着监管水平、施工技艺等方面的差异.通过基桩低应变检测,能够及时发现建设工程中的基桩内部情况和其与桩身完整性之间的关系.当建筑工程以及其他各项建设项目中的基桩桩顶、桩身等部位出现一些异常情况时,在经过基桩低应变检测时,所反映出来的波形也是有所差别的.根据对波型的有效分析,能够及时发现出现缺陷的具体部位,从而积极予以解决.本文主要从基桩低应变检测的内涵出发,通过工程典型案例分析,对基桩低应变检测的波形分析及桩身完整性判定进行了全面而细致的分析和说明.

化工高压阀门壳体超声波检测的波型分析

介绍化工设备定期检验中的高压阀门壳体及带圆孔方型工件的超声波检测方法、原理和波型分析。

基于改进型多分辨小波分析与自适应算法的电网谐波检测的研究

为了更加精确检测出电网谐波,本文采用了一种基于改进型多分辨小波分析与自适应算法、傅里叶算法相结合的电网谐波检测算法,运用到电网谐波检测中。验证结果表明,在电网中含有谐波成分时,此种方法能够准确定位、检测谐波成分,对非稳态信号有较好的检测精度,最终达到消除电网谐波,为用户提供可靠电能质量的目的。

超声波在圆柱形工件中的波型变化

超声波直探头接触法手工检测圆柱形工件曲面时,其声场特征与平面接触工件时有着极大的不同。由于超声波直探头与工件呈线性接触,导致其声场变化,使截面内充满超声场,产生的波型有纵波、横波及沿圆柱表面传播的表面波。根据该声场的特点,结合柱面反射的特殊情况,导致一次底波后产生了不同类型的变型波。通过对三次底波前的变型波的计算和分析,了解了主要变型波的性质和意义,提供了工件内部综合的超声波信息,有助于对圆柱形工件内部质量的评价。

WGL-6微机故障录波分析装置设计方案

电力系统的发展对变电站故障录波装置提出了更高的要求 ,计算机软硬件技术的飞速进步为微机型故障录波装置的性能改善提供了必要条件。介绍了新型WGL - 6型微机故障录波分析装置技术特点、硬件结构配置、性能以及软件包的组成及其功能 ,还介绍了故障录波的全过程。

60只正常人耳脑干听诱发电位测定

作者于1992年10月～12月使用脑干反应测听仪对耳科某些疾病进行测试，其间对60只正常耳主波的波Ⅰ、Ⅲ、Ⅴ潜伏期及各主要峰间期值进行测定并经统计学处理，现将结果报告如下。

红庆梁矿井副立井大罐笼提升系统振动实验研究

为提高副立井提升系统的安全性能,文章针对红庆梁矿井副立井特大罐笼提升系统(每次提升300人)进行振动了实验研究,对提升机、电机、导向轮以及罐笼进行了振动测试和数据采集分析。经分析研究确定提升机、电机、导向轮均运行良好,但罐笼在运行速度为2. 9m/s处发生了共振。通过实验研究找出罐笼共振频率约为39Hz,并给出了解决罐笼共振的技术措施。

Research on identifying the dynamic error model of strapdown gyro on 3-axis turntable

The dynamic errors of gyros are the important error sources of a strapdown inertial navigation system. In order to identify the dynamic error model coefficients accurately, the static error model coefficients which lay a foundation for compensating while identifying the dynamic error model are identified in the gravity acceleration fields by using angular position function of the three-axis turntable. The angular acceleration and angular velocity are excited on the input, output and spin axis of the gyros when the outer axis and the middle axis of a three-axis turntable are in the uniform angular velocity state simultaneously, while the inner axis of the turntable is in different static angular positions. 8 groups of data are sampled when the inner axis is in 8 different angular positions. These data are the function of the middle axis positions and the inner axis positions. For these data, harmonic analysis method is applied two times versus the middle axis positions and inner axis positions respectively so that the dynamic error model coefficients are finally identified through the least square method. In the meantime the optimal angular velocity of the outer axis and the middle axis are selected by computing the determination value of the information matrix.

Short-term forecasting optimization algorithms for wind speed along Qinghai-Tibet railway based on different intelligent modeling theories

To protect trains against strong cross-wind along Qinghai-Tibet railway, a strong wind speed monitoring and warning system was developed. And to obtain high-precision wind speed short-term forecasting values for the system to make more accurate scheduling decision, two optimization algorithms were proposed. Using them to make calculative examples for actual wind speed time series from the 18th meteorological station, the results show that: the optimization algorithm based on wavelet analysis method and improved time series analysis method can attain high-precision multi-step forecasting values, the mean relative errors of one-step, three-step, five-step and ten-step forecasting are only 0.30%, 0.75%, 1.15% and 1.65%, respectively. The optimization algorithm based on wavelet analysis method and Kalman time series analysis method can obtain high-precision one-step forecasting values, the mean relative error of one-step forecasting is reduced by 61.67% to 0.115%. The two optimization algorithms both maintain the modeling simple character, and can attain prediction explicit equations after modeling calculation.

Structural Decomposition Analysis on Energy Intensity Changes at Regional Level

As China's energy intensity fluctuated in recent years, it is necessary to examine whether this fluctuation happened at a regional level. This paper establishes a decomposition model by using the structural decomposition analysis (SDA) method at a regional level. Then this model is employed to empirically analyze the changes of Beijing's energy intensity. The conclusions are as follows: during 2002-2010, except petroleum, the energy intensity decreased and the changes were mostly attributed to the technology changes, while the final use variation actually increased the energy intensity; comparing different periods of 2002-2010, the decline rates of energy intensity for coal and hydropower were decreasing, resulting from the production technology being more energy-intensive than before; the energy intensity changes of petroleum firstly increased substantially and then decreased moderately.

Loop Soliton Solutions of a Short Wave Model for a Degasperis-Procesi Equation

An analytic method, i.e. the homotopy analysis method, was applied for constructing the solutions of the short waves model equations associated with the Degasperis-Procesi (DP) shallow water waves equation. The explicit analytic solutions of loop soliton governing the propagation of short waves were obtained. By means of the transformation of independent variables, an analysis one-loop soliton solution expressed by a series of exponential functions was obtained, which agreed well with the exact solution. The results reveal the validity and great potential of the homotopy analysis method in solving complicated solitary water wave problems.

Dynamic simulation of hydrodynamic model of drum level wave action and sloshing

In order to build the model of the drum level wave action and sloshing, based on the method of modularization modeling, the hydrodynamic model of drum level wave action and sloshing was developed, and dynamic simulation researches were carried out based on the model. The results indicate that both drum level and drum length have functional relations with period of drum level wave action and sloshing. When the drum level decreases or drum length increases, the period of drum level wave action and sloshing increases, density of liquid and number of sub-module division have little influence on the period of drum level wave action and sloshing. The model was validated by the analytical solution theory of liquid’s wave action and sloshing in cuboid container, and the 3D graphics of drum level wave action and sloshing was also obtained. The model can dynamically reflect the rules of wave action and sloshing of water in the container exactly.

Capital Account Openness,Exchange Rate Volatility and Economic Growth:International Experiences and Implications

Based on the Barro classical growth model, this paper introduces capital account openness and exchange rate volatility to conduct an empirical analysis using the panel data of 182 countries(regions) during 1970-2013 to examine the combined effects of capital account openness and exchange rate risks on economic growth. Our findings are as follows:(1) Without considering exchange rate volatility, capital account openness is subject to a threshold effect, i.e. capital account openness significantly promotes the economic growth of middle-and high-income countries but exerts the opposite effect on low-income countries; and(2) after exchange rate volatility is taken into account, the growth effect of capital account openness is reduced and the greater the exchange rate volatility is, the smaller the marginal effect of capital account openness will be; sample-specific results also proved the existence of the threshold effect. This paper offers the following implications:(1) The effect of capital account openness can be better examined based on risk factors;(2) moderately controlling exchange rate volatility is conducive to acquiring greater benefits from capital account openness; and(3) the threshold effect of capital account openness cannot be overlooked.

Symmetry Analysis of Two Types of (2+1)-Dimensional Nonlinear Klein-Gorden Equation

By means of the classical symmetry method,we investigate two types of the(2+1)-dimensional nonlinearKlein-Gorden equation.For the wave equation,we give out its symmetry group analysis in detail.For the secondtype of the(2+1)-dimensional nonlinear Klein-Gorden equation,an optimal system of its one-dimensional subalgebrasis constructed and some corresponding two-dimensional symmetry reductions are obtained.

Operational Modal Analysis of a Ship Model in the Presence of Harmonic Excitation

A ship is operated under an extremely complex environment, and waves and winds are assumed to be the stochastic excitations. Moreover, the propeller, host and mechanical equipment can also induce the harmonic responses. In order to reduce structural vibration, it is important to obtain the modal parameters information of a ship. However, the traditional modal parameter identification methods are not suitable since the excitation information is difficult to obtain. Natural excitation technique-eigensystem realization algorithm （NExT-ERA） is an operational modal identification method which abstracts modal parameters only from the response signals, and it is based on the assumption that the input to the structure is pure white noise. Hence, it is necessary to study the influence of harmonic excitations while applying the NExT-ERA method to a ship structure. The results of this research paper indicate the practical experiences under ambient excitation, ship model experiments were successfully done in the modal parameters identification only when the harmonic frequencies were not too close to the modal frequencies.

Response of air gap and slamming loadings on semi-submersible platform

The present research deals with the numerical prediction of the air gap within the 6th generation of deepwater drilling floating semi-submersible platform and the experimental studies on the slamming loadings onto the structure. The survivability of the floating model with a mooring system was tested under extreme wave of 10-year return period. In the numerical simulation of the Gaussian method,the narrow band model was applied to obtain the first-order wave surface equation and the modified second-order wave surface equation. The hydrodynamic responses of the floating body,i.e. radiation damping,added mass,second-order wave excitation force and drifting force,were computed by using the potential flow theory based on higher order boundary element method in frequent domain. In the experimental analysis,high-frequency sensors were installed at the lower deck to measure the wave slamming loads. Equivalent truncated mooring system was applied to make sure position of the floating body in the wave tank. The comparison between the numerical and experimental results showed the numerical model underestimated the air gap of the floating body. Nevertheless,the predictions of the high risk spots underneath the floating deck that is prone to wave slamming obtained from both models were agreeable to each other. The experimental results also revealed that the wave slamming events often occurred at the connection point between the rear columns and the lower deck.

Investigation on the Cause of Excessive Vibration of an Offshore Platform

An offshore platform of jacket type in Bohai Bay vibrated excessively under design environmental conditions, which had affected the normal operation of the platform. In order to mitigate the vibration of the platform, it is essentially important to explore the cause of the vibration. So the objective of this study is to investigate the cause of the excessive vibration. In this paper, dynamic characteristics of the offshore platform is analyzed by numerical simulation using finite element (FE) modeling. For further verifying the numerical results, model experiment is conducted. Numerical and experimental results demonstrate that there is relative movement and impact between the piles and the jacket, i.e. the piles and the jacket didnt connect well to an entity. It is this cause that the stiffness of the platform decreases and the impact between piles and the jacket legs induces excessive vibration. And also the grouting measure is advised to reduce the vibration of the offshore platform according to the analysis results.

Model identification of hydraulic flight simulator based on improved particle swarm optimization and wavelet analysis

A new model identification method of hydraulic flight simulator adopting improved panicle swarm optimization （PSO） and wavelet analysis is proposed for achieving higher identification precision. Input-output data of hydraulic flight simulator were decomposed by wavelet muhiresolution to get the information of different frequency bands. The reconstructed input-output data were used to build the model of hydraulic flight simulator with improved particle swarm optimization with mutation （IPSOM） to avoid the premature convergence of traditional optimization techniques effectively. Simulation results show that the proposed method is more precise than traditional system identification methods in operating frequency bands because of the consideration of design index of control system for identification.