An intelligent approach to prediction and control ground vibration in mines

Drilling and Blasting are still considered to be the most economical method for rock excavation either on surface or underground. The explosive energy, which breaks the rockmass, is not fully utilized for this purpose. Only 20–30% of explosive energy is utilized for fragmenting the rockmass and the rest wasted away in the form of ground vibration, air blast, noise, fly rock, back breaks, etc. Among them, ground vibration is considered to have the most damaging effect. A number of predictor equations have been proposed by various researchers to predict ground vibration prior to blasting. Still, it is difficult to recommend any one predictor for a particular ground condition because ground vibration is influenced by a number of parameters. These parameters are either controllable or non-controllable like blast geometry, explosive types, rock strength properties, joints patterns, etc. In the present paper, an attempt has been made to predict the ground vibration using an Artificial Neural Network incorporating large number of parameters, which affect the ground vibration. Results are also compared with the values obtained from regression analysis and observed field data sets. Finally, it is found that the neural network approach is more accurate and able to predict the value of blast vibration without increasing error with increasing number of inputs and non-linearity among these.     

Nonlinear analysis on the coupling process of electromagnetic vibrator and earth

Vibrator is an excitation equipment of the vibratory source in the seismic exploration[1―3]. In order to ap-proach the δ function, dynamite can be used to release high energy in an instantaneous explosion and form the seismic wavelet. On the other hand, a portable vi-brator sweeps a low energy signal for a long time to simulate the function of an explosion source. The re-flection signal of the portable vibrator is estimated for time-delay by digital cross correlation technology, and the disp…     

Model Test Study on Ice Induced Vibration of A Compliant Conical Structure

1.Introduction Inthedesignofoceanengineeringstructuresforcoldregioncountries,iceloadsarealwaysthe controlloads,andthedesignofice resistingstructuresisoneoftheimportantdesignaspects.Fornat uralseaice,theflexuralstrengthisalwaysonethirdofthecompressivestrength.Soconicalstructures thatcouldinducethebendingfailureoficesheetsarewidelyusedinthedesignsofice resistingstruc tures.Forexample,theplatformKullukintheBeaufortSeaisaninvertedconicalstructure,andan upward downwardbendingconeisusedonplatformJ…     

海洋平台磁流变阻尼器半主动控制研究

基于现代最优控制理论建立海洋平台磁流变 (MR)半主动控制系统的数学模型 ,采用白噪声过程通过滤波器来近似随机波浪力谱。以典型导管架平台为算例 ,对磁流变阻尼器进行了参数设计。分析了 MR阻尼器对海洋平台振动控制的有效性 ,仿真结果表明 ,采用磁流变阻尼器对海洋平台进行半主动控制能够有效的减小平台的动态响应。     

压弯载荷下焊趾表面裂纹工程萌生寿命预测

首先定义焊趾处从无裂纹到检测到表面裂纹长度达到 1.5mm时对应的循环次数为裂纹“工程萌生寿命”。给出了基于修正Neuber法并考虑焊接残余应力等影响的焊接结构焊趾裂纹工程萌生寿命计算方法。用成一定角度对接焊板试件和轴向加载获得压弯组合应力 ,以 980钢板焊接件为试件 ,在压弯组合应力的作用下 ,对焊趾表面裂纹萌生寿命进行了实验研究 ,确定了焊趾处的疲劳缺口系数。该结果可用于疲劳热点部位的受力特征为压弯组合应力的潜艇耐压壳、压力容器等的某些重要焊接结构疲劳计算     

局地海冰数值预测的冰激结构响应计算

在渤海海冰数值预测的基础上，通过渤海海冰的热力—动力模型，对油气作业区的冰厚、冰速、冰温等海冰参数进行短期数值预测，并以此对海冰的盐度、卤水体积、弯曲强度等海冰物理力学参数进行推算，进而对冰激平台结构响应进行计算分析。以辽东湾JZ20-2油气田的MUQ平台为例，对1999／2000年冬季的冰激结构振动响应进行了预测，其结果与实测情况较为吻合。     

Simplified Computation Method of Vibration Characteristics of Jacket Platforms

In this paper a simplified computation method of natural frequency of jacket platforms is given. Shear, bending and rotary inertia effects are considered in the equation, while the jacket shape, rotary inertia and centralized mass of the platform top are all determined by using a coefficient-revising method.     

Seismic Response Reduction for Fixed Offshore Platform by Tuned Liquid Damper

An approach to seismic response reduction for offshore platforms by the use of the tuned liq-uid damper is presented in this paper.First of all,the effects of the tuned frequency ratio and excited fre-quency ratio on the seismic response reduction of the platform structure are investigated.Based on the re-sults,a mechanical model and equation of motion for the TLD-platform system are established.And theneffectiveness of the appraoch is verified by numerical calculation.     

深海采矿立管在波流载荷下的弯矩响应分析

采矿立管是深海采矿系统的重要组成部分，立管的弯矩分析是确保立管正常使用的重要指标。立管所处海洋环境复杂，且立管底部的自由边界条件使得立管弯矩特性难以分析。本文基于波浪理论，使用Abaqus 有限元软件建立海洋采矿立管的模型，运用Abaqus中的AQUA海洋工程模块，考虑立管在轴向力、自重、浮力、波浪载荷、海流载荷及模拟海上平台水平和升沉运动共同作用下，对采矿立管进行弯矩分析，计算了提升泵不同安装位置、不同中继仓重量变化对弯矩的影响，结果表明：提升泵会增大安装位置的弯矩幅度，且安装在不同位置对立管弯矩会产生叠加影响；中继仓重量的增加提高了立管整体稳定性，但会使提升泵处弯矩波动产生向中部延伸的不利影响。     

基于MEMS的室内定位误差修正方法研究

根据室内惯性定位存在误差累积的特点,建立广义似然比检测的方法进行零速度检测,利用Kalman滤波对检测到的"零速度"时刻进行零速修正(zero velocity update,ZUPT),从而有效降低系统累积误差。但行人行走过程中存在的无效振动,导致测得的加速度和角速度数据中出现明显的噪声,这对长时间定位精度产生较大的影响。文中提出在利用Kalman滤波进行误差校正之前首先采用Butterworth低通滤波滤除加速度和角速度数据中由无效振动引起的高频部分,即噪声部分,从而消除行人运动过程中的无效振动对定位精度的影响。