非等间距改进加权GM(1,1)模型在基坑变形监测中的应用

基坑开挖和人为因素的影响,会使基坑在短时间内产生较大变形,针对现有非等间距GM(1,1)模型在处理突变数据上预测精度低、残差大,文中在非等间距加权GM(1,1)模型的理论基础上,提出一种非等间距改进加权GM(1,1)模型,结合实际基坑工程实例,分别用两种模型对基坑监测点沉降进行拟合预测并与实际值比较。通过模型精度检验,结果表明:非等间距改进加权GM(1,1)模型相对传统的非等间距加权GM(1,1)模型预测精度高,更有利于及时掌握基坑变形情况。     

基于GM(1,1)改进模型在变形预测中的应用研究

传统GM(1,1)模型在工程变形预测中受到众多不确定性因素的影响,会导致预测精度低、残差大。因此,文中对传统GM(1,1)中原始数据、初始值、以及背景值进行改进。最后以某大坝边坡监测点的沉降位移为例,分别用两种模型对该监测点位移进行拟合预测并与实际值比较。结果表明:改进模型精度优于传统模型,预测值更接近真实值,在实际工程中有更好的应用价值。     

灰色系统预测在基坑信息化施工中的应用

基坑工程系统是一个灰色系统。根据灰色系统理论，建立了基坑变形的GM（1，1）预测模型。根据工程实例的位移及沉降观测值对后续施工中的变形值进行预测，并用工程实例后续监测值加以验证。研究结果表明，基坑变形的灰色预测模型具有较好的精度，对指导基坑开挖和支护具有积极意义。     

某基坑变形的综合预测模型

在分析BP神经网络和灰色模型群的变形预测基本原理的基础上,以某基坑为例,分别构建了基于BP神经网络的预测模型、基于灰色模型群的预测模型以及基于BP神经网络模型和灰色模型群的综合预测模型,预测了该基坑开挖过程中产生的变形值。研究表明:综合预测模型的预测精度优于其余两类模型,对于提高基坑的变形预计精度有一定的参考价值。     

新陈代谢DGM(1,1)模型在基坑沉降预测中的应用

该文结合基坑沉降监测实例,对沉降数据进行分析,发现沉降速率越来越快,为更合理的对这种增幅较大的累计沉降值做出合理的预报,本文采用GM(1,1)、DGM(1,1)、新陈代谢GM(1,1)和新陈代谢DGM(1,1)四种模型对基坑沉降进行预测。结果表明新陈代谢DGM(1,1)预测模型提高了预测稳定性,新陈代谢DGM(1,1)预测模型与另外三种模型相比,精度有较大幅度提高,残差值增加缓慢,近似于一条水平线,预测值与实测值非常接近,且适用于长期预测,这是另外三种模型所不具有的。对于增幅较大的累计沉降量,新陈代谢DGM(1,1)模型具有较高的预测精度,对其他类似基坑监测具有一定的借鉴意义。     

基于背景值优化与初值修正的灰色模型在沉降变形预测中的应用

灰色GM(1,1)模型具有要求样本数据少,运算方便,短期预测精度高等优点,因此得到广泛应用。在沉降变形预测中,数据拟合和预测精度主要依赖于模型的结构参数,故在沉降变形预测中为提高预测精度,该文从传统GM(1,1)模型初值、背景值等入手,探讨了将初值修正、背景值优化后的预测数据进行组合的方法。该方法充分利用新信息、数据优化后的优越性,提高模型的预测精度;同时通过实例证明得出该组合模型比单一模型、传统模型预测精度更高,达到了较好的预测效果。     

基坑工程稳定性分析与预测的两种方法

从变形与位移的角度来考察基坑稳定性可以避开繁琐复杂的理论分析和计算工作,快速有效地对基坑工程的稳定性进行预测。建立了预测基坑周边地表沉降量及基坑稳定性的BP网络模型,并推导了求算基坑周边地表沉降量的估算式。结合具体工程实例对建立的网络模型和推导的估算式进行了验证,并对两类方法的求解条件、预测精度及适用范围等进行了比较说明。     

顾及开挖深度的灰色系统模型在基坑沉降预测中应用

为提高基坑开挖过程中变形监测实时预测的准确性与可靠性,文章结合灰色系统理论,考虑关于监测数据与基坑开挖深度之间的关系,建立离散灰色系统模型,利用该模型对原始沉降数据进行分析预测,并通过实验数据对比分析得出,利用离散灰色系统模型预测的结果与实测数据相吻合,预测精度可靠,且具有一定的参考价值。     

基于滑动平均-灰色Verhulst模型的深基坑中长期变形预测

准确的深基坑变形预测和控制是当前地下工程监控测量研究领域的热点问题,尤其是深基坑变形的中长期预测,对保障现场人员和财产安全具有重要的预警作用。以某地铁盾构始发竖井深基坑为工程背景,采用滑动平均法(MA)对基坑变形现场实测的地表沉降原始数据进行去噪处理,增加监测数据的权重,然后引入灰色Verhulst模型对去噪后的数据进行中长期拟合预测,最后对比分析灰色GM(1,1)模型、灰色Verhulst模型、滑动平均-灰色Verhulst模型的预测精度。结果表明:滑动平均-灰色Verhulst模型的预测精度较高,适用于基坑中长期变形预测。该结果可为提高类似变形问题的预测精度提供启示作用。     

GA-BP神经网络在深基坑变形预测中的应用

选取深圳前海某基坑工程的监测数据为例,分别采用BP神经网络和GA-BP神经网络两种模型对基坑支护结构进行变形预测,将变形预测值与实际监测数据对比分析,指出遗传算法优化的GA-BP神经网络模型能更精确的预测基坑变形。     

Current situation and future trend of China rare earth luminescent material industry

<正>Rare earth luminescent material is one of the most important application sectors of rare earths.China enjoys the exceptional advantage to develop rare earth luminescent material for its abundant rare earth resources.After several decades'endeavor,China's rare earth luminescent material industry,headed by rare earth phosphor for lamp and LED and high efficient rare earth energy-saving light source,has been gradually developed into a scale industry.China has become a major production base of rare earth phosphor for lamps and rare earth     

China rare earth market review

正June 1~10,2014Rare earth market remained weak.Quoted price of rare earth products was similar to that in May.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,polishing powder and ceramic industries remained inactive.Demand from downstream industry was soft.Consumers purchased on their needs.Suppliers had strong intention to sell.Prices of rare earth products     

Annual Report analysis of Chinese rare earth-related listed companies in 2013

<正>Chinese rare earth-related listed companies have published their 2013 annual reports.It can be understood from their reports that production and operation activities of Chinese rare earth-related companies were still heavily affected by macro economy and industrial policies.They basically followed the steps of national economy.In 2013,world economy recovered slowly but the economy     

Market opportunities and challenges for rare earth polishing powder

正1.Status of rare earth polishing powder Rare earth polishing powder with high content of cerium oxide began to replace iron oxide for glass polishing and became one of the key materials in glass polishing process since 1940.Compared with traditional iron oxide,rare earth polishing powder has many advantages,such as fast polishing rate,high polishing quality and long service life.It can achieve good surface quality and improve operation conditions.For example,in lens polishing,the polishing work that cerium     

Baotou Research Institute of Rare Earths developed a new RE alloy preparation technology

正Pyrometallurgy Laboratory of Baotou Research Institute of Rare Earths had independently developed a new preparation technology of rare earth alloy for NdFeB.The alloy can remarkably enhance the coercivity of NdFeB magnet but also evidently reduce the production cost of the magnet.The new master alloy was prepared in the kA pilot-scale electrolytic cell by the independent technology.The rare earth master alloy can be used as the raw material for NdFeB.Compared     

矿用防爆轴流对旋主要通风机叶片ANSYS模态分析及应用

高效节能矿用防爆对旋主要通风机的叶片是主要通风机运行的关键部件,叶片在运行时不断受到气流的作用力,从而使叶片产生振动,当叶片振动的频率与叶片的固有频率接近时,容易产生共振从而导致叶片的断裂。一旦叶片断裂时,对主要通风机的安全运行产生致命的影响,从而导致矿山、化工等企业发生重大事故,将会产生不可估量的损失。基于有限元分析软件ANSYS,对高效节能矿用防爆轴流对旋主要通风机叶片进行模态分析及产生对应的六阶模态频率,对主要通风机叶片的运行频率、固有频率及产生的共振问题进行了原理分析,并且解决了叶片频率共振的问题,从而为主要通风机叶片结构设计提供理论依据,并对主要通风机叶片的安全运行提供保障。     

2013 NdFeB export analysis

<正>China totally exported nearly 24,000 tonsof NdFeB products during 201 3,including 18,825 tons of permanent magnet,valued USD 1.34 billion at an average price of 71.4 USD/kg;3,277 tons of NdFeB magnetic powder,valued USD 1 01 million at an average price of 30.9 USD/kg;1,334 tons of strip casting ribbon,with total export value of USD 74million at an average price of 55.3 USD/kg;and 586     

Market and recycling of NiMH battery

<正>Market status and future trend of NiMH battery1.Global market of small NiMH battery Global market size of small NiMH batteries declined year on year since 2011.The trend will continue to 2018,at the rate of 5%to 10%annually.Demand for small NiMH batteries will be stable gradually.Many electrical apparatuses are powered by the built-in lithium battery today,which is the main reason for the shrunk market of small NiMH batteries.But,for some products,small NiMH     

China rare earth market review

正September 1-10,2014 Affected by the National Day holiday,rare earth transaction was stagnant and the market showed a weak steady state.As there was no good news for downstream market,some products with flat demand would likely rally slightly for some time to     

唐口煤矿深部复杂开采工作面瓦斯分源涌出规律研究

研究工作面瓦斯涌出规律对工作面瓦斯治理有重要意义。为了得到唐口煤矿深部3号煤层复杂开采条件下工作面回采时期瓦斯涌出时空演化规律,选取6304工作面作为对象,采用实测方法研究6304工作面瓦斯涌出规律。结果表明:6304工作面瓦斯涌出量为6.534 m³/min,其中煤壁占34.27%,落煤占29.62%,采空区占36.11%;沿工作面倾向由低到高,瓦斯浓度整体为上升趋势,其中1—76号架工作面瓦斯浓度小于0.20%,76—102号架瓦斯浓度上升明显,最大为0.387%;上隅角的后部采空区是工作面的瓦斯主要涌出源,上隅角1号测点瓦斯浓度0.78%,上隅角周边3号、5号、7号、8号、9号测点瓦斯浓度平均为0.643%;周期来压时,上隅角瓦斯相对平时较高。研究为针对性的瓦斯分源监控与灾害防治提供基础。