非周期变尺度随机共振在锚杆无损检测中的应用

在强噪声下检测锚杆微弱信号一直是实际工程中的难题。随机共振与以往去噪方法不同,其利用噪声能量来增强被噪声埋没的微弱信号。经典的随机共振只适合于小参数信号(信号频率、信号幅值、噪声强度均远小于1)的检测,而应力波反射法采集到的锚杆信号属于衰减振荡的暂态信号,具有非周期性、大参数等特点,因此采用非周期变尺度随机共振方法处理锚杆信号。针对非周期随机共振,综合峭度指标与互相关系数指标的各自优缺点,采用加权峭度作为其度量指标。变尺度随机共振法对幅值进行归一化、对频率进行线性压缩,使锚杆信号满足经典随机共振的要求。通过处理非周期大参数的仿真信号和实际工程中的锚杆振动信号,验证了非周期变尺度随机共振的有效性。     

基于相位推算法的锚杆施工质量无损检测分析方法

将相位推算法引入到锚杆施工质量的无损检测分析中,首先对采集信号进行傅氏变换和数字滤波,将采集信号的主频作为相位推算法计算式中的频率初始值,再利用相位计算结果随时间的变化规律,判断锚杆底端或缺陷位置处的反射信号.通过对实测锚杆资料的处理结果来看,在锚杆底端或缺陷位置处信号的相位曲线会发生明显的畸变,由此可准确判断反射信号的位置,确定锚杆长度、灌浆饱满度以及缺陷位置.研究结果表明,利用瞬时相位曲线可迅速准确地识别锚杆底端与缺陷处的反射信号,由此分析锚杆施工质量,提高了应力波无损检测方法解释结果的可靠性.     

基于半波偶极子理论的锚杆长度无损测量仪设计

针对声频应力波法应用于金属锚杆无损测量时反射波信号处理复杂及测量长度受限的问题,设计了一种基于天线理论的锚杆长度无损测量仪,通过添加一根金属参考线的方式,将单根金属锚杆等效为半波偶极子天线,采用AD9913作为天线馈源产生0~100MHz的正弦扫描信号耦合进金属锚杆,检测金属锚杆首次发生谐振时对应的正弦信号的频率,依据谐振频率与波长以及波长与天线长度的关系,计算出金属锚杆的长度。在整个测量过程中,电路对信号的相位特性不需要严格约束,对10m长以上的锚杆进行实际测量,绝对误差可控制在5%以内。     

20~1 000 kHz超声导波用于锚杆锚固质量检测的探索

为使超声波无损检测技术应用于锚杆锚固质量的检测，采用理论分析和实验室测试的方法对超声导波在锚杆中的传播规律进行了研究。在20～1 000 kHz导波频率范围内，对不同锚固质量的锚固锚杆进行了扫频，并根据实验结果得出了群速度随频率变化曲线。研究结果表明：频率较低时，同一频率导波在不同锚固质量的锚杆传播的群速度不一样，可用于锚杆锚固质量的检测；频率较高时，它们的群速度几乎一致，可用来检测锚固锚杆的长度，但存在一些可用于锚杆锚固质量检测的导波。     

基于数值模拟的锚杆锚固缺陷检测研究

针对锚杆锚固中缺陷检测质量不高的问题,本文采用电磁超声技术完成锚杆质量检测,首先利用PCDISP软件获得频散曲线,确定最佳激励频率;然后应用COMSOL有限元仿真软件建立锚杆锚固三维模型,并设定偏置磁场最优参数,分析了锚固的有效长度、锚杆锈蚀深度和缺陷的大小对检测波形的影响;最后搭建物理实验平台,对采集到的回波信号进行分析,实验数据验证了数值分析结果的有效性。结果表明:电磁超声技术用于锚杆锚固质量检测,能有效检测出锚固有效长度和缺陷位置。     

煤矿锚杆支护无损检测技术与应用

为了寻求能快速、实时、无损检测煤矿井下巷道锚固质量的方法,研究了应力波在井下锚杆系统中的传播和反射原理,研制成功本安型锚杆无损检测仪.以外力给锚杆外露端施加一瞬态激振力,所产生的应力波在锚杆杆体中传播,遇锚固位置或里端面反射,由锚杆外露端头的传感器接收反射信号,通过对所接收的反射信号进行时域、频域的处理分析,获得锚杆的锚固长度、工作荷载、极限承载能力等参数.锚杆检测仪经过大量的实验室和井下现场测试,结果表明:检测仪检测数据与锚杆实际参数相差在7%以内.     

磁致伸缩扭转导波在纤维增强塑料锚杆中的应用

针对电磁超声信号信噪比低、回波特征不明显的问题,本文对磁致伸缩扭转导波特性进行了分析,扭转导波非频散适合信号处理,且在传播过程中能量衰减较小。利用ANSYS有限元仿真软件分析了扭转导播在纤维增强塑料(FRP)锚杆内的位移、功率流特性;搭建了物理实验平台,在FRP锚杆内激励和接收磁致伸缩扭转导波信号,对采集到的回波信号进行CEEMD-LMS算法滤波;实验数据验证了数值分析结果的有效性。结果表明:磁致伸缩扭转导波在FRP锚杆内的传播功率趋向于表面,适用于FRP锚杆表面缺陷检测;经CEEMD-LMS滤波算法处理后的磁致伸缩导波信号信噪比得到提升;磁致伸缩扭转导波技术可对有周向缺陷的FRP锚杆长度、缺陷位置进行识别。     

循环自相关函数在滚动轴承故障特征提取的应用

应用循环自相关函数和快速谱峭度相结合的方法,对滚动轴承早期故障诊断进行分析研究。首先利用谱峭度方法确定滚动轴承振动信号的最佳带通滤波器,然后利用循环自相关函数对滤波后的信号进行解调,提取出滚动轴承故障特征频率,有效地减少了噪声信号的干扰且增强了故障信号。通过仿真与实验数据的轴承故障振动信号验证所提方法的有效性。     

注浆锚杆锚固质量的无损检测试验研究

注浆锚杆广泛应用于深部软岩巷道支护,其注入浆液的密实度极大的影响着注浆锚杆的锚固质量,但是目前如何快速、准确、大范围的检测锚固质量尚无有效的技术手段。文章基于弹性应力波在注浆锚杆锚固体中传播时透射与反射规律,对注浆锚杆自由段、锚固段长度和锚固段内缺陷位置和长度进行了无损检测试验研究,并采用小波变换理论对试验信号进行了分析。研究结果表明：通过小波工具箱中的低通滤波器对信号进行低频分析,能够准确的识别出注浆锚杆的自由段长度|通过高通滤波器对信号进行高频分析,能够准确的识别出注浆锚杆的锚固段长度,锚固段内缺陷长度以及缺陷的具体位置。研究成果可为进一步开发注浆锚杆锚固质量无损检测技术和方法提供试验基础。     

谐波小波在锚杆动测信号滤波中的应用

如何有效检测锚杆支护过程中支护和锚固状态,为巷道支护的稳定和安全提供保障一直倍受关注。根据锚固质量无损检测信号的频段分布特点,基于离散谐波小波变换理论,从锚固检测信号中剔除不需要的一些高、低频成分,并利用谐波小波重构算法得到滤波后信号,以有效提取到所关心频段的检测信号。最后将谐波小波变换用于实测锚杆响应信号的滤波处理,结果体现了谐波小波良好的滤波特性。     

China rare earth market review

正November 21~30,2014Due to weak demand from downstream industries,transactions of rare earth in Chinese domestic market were inactive.It was difficult to sell any rare earth products except for dysprosium oxide and terbium oxide.Suppliers lost confidence in recent market.Demand for rare earth products was soft.Consumers continued to take a wait-and-see attitude.Rare earth export market remained slow.     

Current situation and future trend of China rare earth luminescent materialindustry(continued)

<正>Developing ecological lighting source The world is facing the big problem of energy shortage today and the contradiction between economy development and environmental protection is worsened.Therefore,people are more likely to choose an ecological light source that is more energy efficient and environmental friendly.The choice provides great opportunity for the development of rare earth optical material industry in China.The concept of green lighting positions rare earth luminescent material as a leading player in illumination market.The light source of both rare earth luminescent lamp and LED lamp is ecological and energy saving.This is why     

Galaxy Magnets achieved the net profit of 34.02 million yuan in the first six months of 2014

正Galaxy Magnet announced its financial results for the first half of 2014 on August 14.For the first six months ended on 30 June 2014,Galaxy Magnet achieved operation income of RMB 182.3 million,up8.40% over the same period of 2013,and the net profit attributable to the shareholders of the listed company of 34.02 million yuan,increasing 35.49% over the same period of last year.Stable performance increase was led by development of new customers and application market of magnets.     

Rare Earth Application in Steel in China

<正>China has rich rare earth resources.Output of rare earth and steel in China ranks the top first in the world.However,there is still certain distance between the steel produced in China and developed countries from the point of varieties and quality.China still has to import some types of steel.Improving the quality should be emphasiZed in future development of steel industry in China.Rare earth can be used to upgrade traditional steel     

稀散金属产业的观察与思考

分析了近年来国内外稀散金属产业的生产、应用、资源与市场状况.铟锡氧化物靶材、砷化镓晶片、锗红外材料、铼高温合金和硒在电解锰及玻璃的应用等已成为稀散金属的主要应用领域.稀散金属的产量快速增长达到历史高位而导致了市场的失衡.以GaInP_2/GaAs/Ge,CIGS和CdTe为代表的非硅系太阳能电池是稀散金属的新兴应用领域,将给稀散金属带来日益增长的需求.     

China rare earth market review

正November 1~10,2014Chinese rare earth market was still inactive.Demand for rare earth products was weak.Consumers took a wait-and-see attitude for lower price.As it was an off season for rare earth products,it was expected that prices of rare earth could continue turbulence at the bottom in short terms.Due to a sharp drop,demand for rare earth from downstream recovered.Affected by new energy vehicles,wind powder and energy-efficient appliances,production of rare earth permanent     

China rare earth market review

正August 1~10,2014 There was some good news in rare earth industry recently.Restructuring plans of rare earth groups led by Baotou IronSteel Group and Xiamen Tungsten Group respectively have been approved by MIIT.And rare earth storage policy,which had been expected for a very long time,has been launched officially.Pushed by the good news,rare earth price started to rebound since August 5.Price of didymium oxide and dysprosium oxide rose about 1% to 2%,averagely.About 10% of     

China rare earth market review

正July 1~10,2014Due to weak demand from downstream industry and slow transactions,rare earth market remained weak and price of rare earth products continued to decline.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,     

New energy vehicle:an opportunity for rare earth magnets

<正>Extracted from Securities Guide 1.Popularity of new energy vehicles—an irresistible market trend1.1 Progress of new energy vehicles Chinese Premier Li Keqiang said recently on a visit to Xi'an BYD Autos that new energy vehicles,especially new energy bus,can lessen environment and noise pollution.He encouraged the use of new     

Brief news

正Corun invested another 50 million yuan in power battery for HEV Hunan Corun announced on 27 June that they had signed the cooperation agreement to jointly built Corun(Shaoxing)Autos Power Battery System Co.,Ltd.in Shaoxing Binhai New City.According to the announcement,total registered