首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The permeability index for blast furnaces is an important monitoring parameter in their operation. Proper trend prediction of the permeability index is important for good operation. Support vector machines (SVM) combined with wavelet analysis are adopted to build a forecasting model. Four historic values of a permeability index are analyzed by a wavelet analysis via seven levels. Based on eight wavelet analyzed values and combined with operating parameters, eight sub models are built using the least square support vector machines method. The prediction components are reconstructed to obtain a forecast. The details of modeling, validation and result analyses are presented.  相似文献   

2.
The structure parameters of honing wheel have effects on machining accuracy in ultra-precision plane honing. This paper put forward to the optimization of structure parameters. By calculating the machining accuracy coefficient and wear coefficient of triangle radial structure honing wheels, it is obvious that the suitable triangle radial structure honing wheel can improve machining accuracy of workpiece.  相似文献   

3.
A method of diesel engine fuel system fault diagnosis based on wavelet transform and fuzzy C-means clustering is presented. Five characteristic parameters of reflecting fault state are distilled with wavelet transform of pressure wave of high-pressure oil pipe of diesel. The theory and generic approach of fuzzy C-means clustering algorithm (FCM) is given, and the validity of evaluating fuzzy clustering making use of partition coefficient, partition entropy and parting coefficient is pointed out. Identification of fault mode can be completed utilizing standard fault character modes established by FCM algorithm, and calculating and comparing the similarity degree between this standard mode and sample. The arithmetic is applied to all kinds of typical faults diagnose in the diesel engine fuel system. Measuring results indicate that the precision of fault diagnosis is increased with the analysis of wavelet and FCM.  相似文献   

4.
Complex wavelet transform can characterize the partial feature of the PD signal in time-domain and frequency-domain,and provides the unique phasic information.In this paper,the PD pulse waveforms which are created by 4 typical insulated defects are transformed by complex wavelet,and then the complex wavelet coefficient's real part,imaginary part and compound coefficient are clustered by the Fuzzy c-means,the energy of the cluster is the feature of pattern recognition.Discharge samples are got through large number of experiments,and BPNN can identify the PD created by 4 typical insulated defects effectively.The results show that the feature extracted from compound coefficient is better than the feature extracted form the real part and imaginary part of complex wavelet coefficient or wavelet coefficient.  相似文献   

5.
De_noising algorithm based on traditional wavelet transform may produce artifacts on discontinuities of the signal. The reason is that the de_noising algorithm lacks of wavelet translation invariant. This paper proposes a de_noising method based on translation invariant. The method performs the cycle_spinning for the signal to be analyzed. And then, the soft (hard) thresholding is used to shrink the wavelet coefficient of the signal and reconstruct the signal. Consequently, the shift dependence of wavelet basis is eliminated. This method can suppress the artifacts effectively so that de_noised signal is more smooth and has better approximation to original signal.  相似文献   

6.
鲜食葡萄始终占主导地位是我国葡萄产业发展的一个突出特点.长期以来,我国鲜食葡萄贮运保鲜业一直比较滞后,基本是季产季销,地产地销.因此,我国鲜食葡萄集中产区经常出现采后"运不出、贮不进、销不掉"的被动局面,阻碍了鲜食葡萄产业在适宜栽植区的快速发展.一些非适宜产区为了填补当地鲜食葡萄市场空白,也在积极发展鲜食葡萄生产,其结果必然导致生产成本提高,不利于我国鲜食葡萄的区域化种植和商品化生产基地的建设.  相似文献   

7.
This paper inferred a new high-speed method of tool-life testing from the differential median theorem of the pluralistic function. The characteristic of the method is that by using one cutting edge and doing one wear curve the tool life equation T=Cvx can be obtained.The drain on the workpiece and time of the method decreased by 2/3 as compared with that of the conventional testing method. The test has verified the method in the paper.  相似文献   

8.
为了更好地监测橡胶树的生长状态,客观准确地获取橡胶树的种植的地理位置信息,采用非对称高斯函数对海南岛内MODIS EVI时间序列数据进行滤波处理,定义作物物候特征参数并计算海南岛每个像元的特征参数值;统计分析基于MODIS EVI数据的海南岛橡胶树样区作物关键物候特征参数值变化规律;根据橡胶树样区特征参数值变化规律建立海南岛橡胶树种植信息提取算法,提取结果采用不同比例的橡胶树混合像元分类法表示。根据提取算法对海南岛2011年橡胶树种植信息进行提取,用验证数据对该提取算法进行精度检验与实用性评价,检验结果显示该算法的平均分类精度达85.97%,可以用来提取橡胶树种植信息。  相似文献   

9.
白宗璠  竞霞  张腾  董莹莹 《作物学报》2020,46(8):1248-1257
为了从全波段光谱数据中提取对小麦条锈病敏感的特征参量,提高小麦条锈病遥感探测模型的运行效率和精度,本文首先从惯性权重和粒子更新方式两个方面对传统离散粒子群算法(discretebinaryparticleswarmoptimization, DBPSO)进行改进,利用改进离散粒子群算法(modified discrete binary particle swarm optimization, MDBPSO)从全波段光谱数据中优选遥感探测小麦条锈病严重度的特征变量,然后与冠层日光诱导叶绿素荧光(solar-inducedchlorophyllfluorescence,SIF)数据相结合作为自变量分别利用随机森林(randomforest,RF)和后向传播(backpropagation,BP)神经网络算法构建小麦条锈病遥感探测模型,并将其与相关系数(correlationcoefficient,CC)分析法和DBPSO算法提取特征参量构建模型的精度进行对比分析。结果表明:(1) MDBPSO算法比传统DBPSO算法具有更快的收敛速度和更高的寻优精度,改进前后其迭代次数从395次减少到15...  相似文献   

10.
安徽省冬小麦长势遥感监测与评估方法研究   总被引:4,自引:1,他引:3  
沿淮淮北是安徽省主要的冬小麦种植区,为了对该区域冬小麦长势进行实时、动态地监测,通过采用变化向量分析方法,利用2005-2010年EOS/MODIS数据,在HANTS算法重构无云NDVI时间序列图像以及安徽省冬小麦种植区提取等数据处理基础上,研究基于NDVI变化向量、曲边梯形面积的长势综合监测模型,对研究区的年际与年内长势变化进行时间和空间上的定量分析。结果表明:HANTS处理平滑后的MODIS的10天合成植被指数的年时序曲线有效消除了云和数据缺失的影响,重构后的生长曲线可以更清楚地反应作物生长变化趋势和规律,有利于监测模型的建立;冬小麦种植区提取,大大提高了卫星监测精度,构建的综合监测模型适合单一生长季苗情长势遥感监测,该模型在2011年冬小麦长势评估中取得了良好的监测效果。  相似文献   

11.
12.
考虑实际结构易受荷载、环境温度和测试噪声等不确定性因素的影响,笔者基于区间分析原理提出框架结构不确定性损伤识别方法。利用测试的结构加速度响应数据,建立向量自回归模型,并采用其系数矩阵主对角线的马氏距离作为损伤特征指标。基于粒子群算法建立区间优化求解方法,并与传统的区间组合法和区间叠加法对比。通过提出的区间重叠率指标和区间名义值分别实现损伤定位和损伤程度的识别。数值模拟和实验室框架结构试验结果表明,区间分析能在测试数据较少时实现损伤识别,为损伤识别在实际结构中的应用提供了理论基础和技术手段。  相似文献   

13.
By analyzing shortages of current MSPCA model, an on line multi variable statistical process monitoring method is proposed, which uses some concepts from online multi scale filtering and can be applied to sensor fault diagnosis. In the method, wavelet decomposition is employed to the signals using edge correction filter in a fixed length data window, and then wavelet denoising is conducted with wavelet threshold filtering. Next, an on line multi scale model is constructed for data combining wavelet transformation and adaptive PCA in the previous data window. This model avoids time waste in direct signal denoising and reduces time cost in multi scale data with conventional PCA, which eventually increases accuracy in fault diagnosis. Experiments on eight vibration signals of 6135D diesel engine under severe leak condition prove the practicability and feasibility of the proposed method.  相似文献   

14.
枸杞作为柴达木地区特色经济作物之一,利用高分辨率遥感影像开展枸杞种植区识别与提取,有利于政府和农业部门开展市场调控和作物精细化管理。以柴达木典型枸杞种植区诺木洪农场为例,利用随机森林、Softmax、支持向量机、BP神经网络和最大似然5种分类器开展农场内不同生长年限枸杞种植区精细化提取,并对结果进行精度验证。结果表明:采用随机森林的分类效果最佳,其总体分类精度达到93.8%,Kappa 0.93,采用Softmax、支持向量机和BP神经网络方法也均获得了较高的分类精度,其总体分类精度均达到了86.6%~87.6%,Kappa系数达到0.84~0.86,而最大似然法分类效果最差,其总体分类精度仅为76.9%,Kappa系数为0.73。通过实验利用国产高分辨率卫星结合较优的分类器能够实现包括枸杞等小宗特色经济作物种植区域和种植结构的精细化识别和监测。  相似文献   

15.
This paper studies the fundamental theory of the generalized minimal residual algorithm(GMRES(m))in Krylov subspace and specially the relationship between residual vector and Krylov subspace.The relationship of the algorithm convergence and the subspace be selected is further researched according the linear system about residual vector.It is posed that the convergence can be slowed down because there are so many very small eigenvalue in magnitude.And a accelerated method(AGMRES(m)) is proposed to improve the convergence of the GMRES(m).Theoretical analysis and numerical results show the reliability and efficiency of the algorithm.  相似文献   

16.
A novel audio steganalysis method is proposed.. the audio signal is denoised with wavelet transform. Then, a part of noise signal with different length is intercepted circularly and is used to calculate the cross correlation sequence with the rest of the noise signal. With the wavelet discontinuity detection technique, the feature is extracted from the cross correlation sequence for steganalysis and find out the steg audio. The detection rate is determined by the embedding strength of the secret message other than the embedding capacity. Experimental results show that the more embedding intensity of PN sequence is, the higher the detection rate will be. The detection rate of the algorithm is above 80% when the strength of the PN sequence is about 0.002, which demonstrates that the proposed algorithm has good detection performance.  相似文献   

17.
The method is adopted and developed to keep constant scallop-height in five-axis machining of NURBS surface using flat-end tools to get the CNC tool path. Then, based on the arithmetic of NURBS interpolation, the standard of NURBS during CAM is achieved. As a result, the CC points' quantity is greatly decreased and the problem that the CC path discontinuities of is overcome. Illustrative examples show the substantial improvements achieved over line-interpolation method for decreasing the amount of data on the condition of the same precision.  相似文献   

18.
用遥感影像提取大别山区水稻种植面积——以Landsat 8为例   总被引:1,自引:0,他引:1  
全璟  王渊 《中国农学通报》2019,35(1):104-111
本研究选取安徽省安庆市大别山为研究区,包括太湖县、岳西县、宿松县和潜山县,选取2016年和2017年的6景Landsat 8卫星遥感影像,通过遥感影像提取水稻种植面积,分析大别山区的水稻种植面积分布,并对研究区域的水稻种植面积进行动态实时监测。用遥感解译方法分别提取了研究区内的晚稻种植面积,并利用随机点验证和Kappa系数验证结果精度。结果表明:2017年和2016年水稻种植面积的提取精度分别为93.44%、93.78%,Kappa系数分别为0.86、0.83,证明水稻提取效果精确;对比研究区域各个县内的2017年和2016年晚稻种植面积,发现安庆市大别山区太湖县、潜山县、岳西县的水稻种植面积变化率均在5%以内,属于正常变化,由于2016年宿松县遭遇了水灾,部分农田被淹没,故宿松县2017年水稻种植面积相比2016年增加了13.01%;对比传统的农作物种植面积统计方法,利用遥感的方法更省人力、物力、财力,并且能精确、快速地实现对农作物的实时动态监测。  相似文献   

19.
The accuracy of transformer substation state estimation is widely low,and one reason of that is inaccurate(parameter) of model.Recently,most of papers about state estimation(SE) focus on improving algorithm.Based on classic SE and parameter estimation(PE),this paper takes advantage of the methods that putting parameters into state vector and putting parameters both into state vector and measurement vector in discussing the influence of parameter on transformer substation SE via simulation.The result of simulation shows: First,the error of parameters will be too high if only putting them into state vector,although the result of SE will be much better.Second,putting parameters both into state vector and measurement vector and giving them appropriate coefficient will lead a better result that can be used by engineering.  相似文献   

20.
小波分析在大豆叶绿素含量高光谱反演中的应用   总被引:7,自引:0,他引:7  
实测了不同水肥耦合作用下,大豆冠层高光谱反射率与叶绿素含量数据,并对光谱反射率、微分光谱与叶绿素含量进行了相关分析;采用叶绿素A与叶绿素B诊断波段构建了特定植被指数,对叶绿素A、叶绿素B进行了回归分析;采用小波分析对采集的光谱反射率数据进行了能量系数提取,并以小波能量系数作为自变量进行了单变量与多变量回归分析,对叶绿素含量进行估算。经分析发现,叶绿素A、B与光谱反射率在可见光与近红外波段的相关系数的变化趋势基本一致——在可见光谱波段呈负相关,近红外波段呈正相关,红边处相关系数由负变正。特定色素植被指数可以提高大豆叶绿素估算精度(R2>0.73);小波能量系数回归模型可以进一步提高大豆叶绿素含量的估算水平,以一个特定小波能量系数作为自变量的回归模型,叶绿素A其确定性系数R2为0.76,叶绿素B为0.78;以4变量与9变量回归分析结果表明:叶绿素A实测值与预测值的线性回归确定性系数R2分别大于0.85、0.89;叶绿素B实测值与预测值的线性回归确定性系数R2分别为0.86、0.90。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号