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1.
The application of wavelet analysis in fault diagnosis is growing rapidly.There are many different wavelet base to use but no accepted procedure for choosing among them, the analysis results by using them have great difference. This paper describes the significant properties of wavelet base, and analysis behavior of transient signal in wavelet transform, result on some methods for how to choose wavelet base in analysis transient signal.  相似文献   

2.
The fast wavelet transform (FWT) algorithm in wavelet analysis was introduced in the paper. With quadrature mirror filters (QMF) associated with popular wavelet bases, the fast wavelet decomposition and reconstruction for signals were implemented. Combined with virtual instrument technique, the FWT analysis system for signals was successfully developed. The system can break up signal not only into approximations, which are the high-scale and low-frequency components of the signal, but also into details which are the low-scale and high-frequency components. Especially it can identify singularity signal, which contain some important message of equipment condition and fault, and refine signal from noisy signal, which is corrupted by noise.  相似文献   

3.
Wavelets have been widely applied in such research areas as image processing, computer vision, network management and data mining. Wavelets have many favorable properties, which are hierarchical and multiresolution decomposition structure, linear time and space complexity of the transformations. The paper presents wavelet application on the algorithms of data mining, in cluding as clustering, classification, distributed data mining, similarity search, approximate query processing, visualization and so on. Finally, the paper concludes by discussing the impact of wavelets on data mining research and outlining potential future research directions and applications.  相似文献   

4.
This paper introduces phenomenon of electric erosion of gear and the research condition and evolution of it; puts forward a point of view that a system of electric erosion of gear is a especial tribology system which is in relation to many subjects and in which many phenomena exist and coupling each other , moreover , it is very difficult and complex to study electric erosion of gear by experiment ; have made statistical datas about typical example of electric erosion of gear inland ,at this base ,summarizes characters of electric erosion of gear and the study means of it.  相似文献   

5.
In order to improve the recognition rate of face recognition algorithm, a new algorithm of face recognition is proposed based on Gabor wavelet transform and Supervised Locally Linear Embedding (SLLE). Gabor wavelet is introduced as a method to extract Gabor magnitude features by convolving the normalized face image with multi scale and multi orientation Gabor filters. In the feature extraction module, the dimension of Gabor features is reduced by SLLE. A minimum distance classifier is trained for classification. With the test of the ORL and YALE face database, it is found that 3.5 %~37.8% increase in recognition rate can be achieved compared with other algorithms.  相似文献   

6.
Unbalanced data are a common problem in plant research based on designed experiments. Such data are often conveniently analysed using linear mixed models. Recent developments in mixed model theory have been implemented in major packages. This paper describes the use of the mixed procedure of the SAS System for the analysis of designed experiments. Special emphasis is given to the specification of options as depending on the assumed mixed model and on the unbalancedness in the data. In addition, we consider a compact representation of multiple comparisons for unbalanced data (letter display). Two small data sets are used to exemplify the methods.  相似文献   

7.
《保鲜与加工》1998,(2):94-99
This paper discusses the size of foundation base in reinforced concrete single-foundation under column.The two kinds of direct-calculating formulas have been derived. They are simple and helpful.They can be easily used in foundation design.  相似文献   

8.
The white noise of PD(partial discharge) signal brings great difficult to the PD signal's processing, so eliminating the white noise is a necessary section. There are many methods of eliminating white noise, but none of them are suitable to the PD signal processing. Because PD signal and white noise have different Lipschitz exponents and different wavelet transform features in time-scales, a new eliminating white noise method has been brought forward that has simple operation and meets the timing need of PD signal's processing. After the processing with this method, the PD signal is not distortion and the effect of eliminating white noise is very good. This method can be applied to the processing of PD signal gotten from the site.  相似文献   

9.
A virtual wavelet transform analyzer for the signal analysis based on the direct algorithm is introduced so that the discrete wavelet transform and continuous wavelet transform is maken to signal in the direct algorithm. The authors first introduce the direct algorithm of the WT, which is numerical algorithm obtained from the original formula of the wavelet transform by directly numericalizing. Then some conclusions are drawn on the direct algorithm. The examples are the sampling principle and technology for the wavelets, the limitation of the scale range of the wavelets and the measures to solve the edge phenomenal in the direct algorithm of the discrete wavelet transform, and some conclusions in the direct algorithm of the continuous wavelet transform. The virtual wavelet transform analyzer for the signal analysis based on the direct algorithm explored based on these studies and combined with virtual instrument technique can make the discrete wavelet transform and continuous wavelet transform to signal with any basic wavelet. It can be applied in studying the property of any basic wavelet and learning the theory on the wavelet transform, and also in making some engineering signal analysis. In the end, the authors give some typical examples for the application of the virtual analyzer. These examples show that the analyzer can be applied in many situations.  相似文献   

10.
The American put valuation problem is very important and complicated in the Option Pricing Theory (OPT), and so far the appropriate continuous-time pricing model and compact valuation formula for the American put option have not been found. On the basis of the research works of many scholars such as Black, scholes, Parkinson, Brennan, Schwartz, Rendleman, Bartter, Cox, Ross and Rubinstein etc., making use of the notion of limitation and the binomial approach, this paper constructs and realizes gradually approaching algorithm of pricing American put options. Its reasonability, convergence and validity are tested by computer programming. The results show that this algorithm can effectively resolve the American put valuation problem.  相似文献   

11.
Grain legumes contribute significantly to total world food production. Legumes are the primary source of dietary proteins in many developing countries, where protein hunger and malnutrition are widespread. Grain legumes germplasm constitute ~15% of the 7.4 M accessions preserved globally. Nearly, 78% of the CGIAR??s, 0.217 M accessions, have been characterized, compared to 34% of national genebank collections. Interestingly, limited data on grain quality are available as the primary focus has been on morpho-agronomic traits. Clearly, more resources should be targeted on biochemical evaluation to identify nutritionally rich and genetically diverse germplasm. The formation of core and mini core collections has provided crop breeders with a systematic yet manageable entry point into global germplasm resources. These subsets have been reported for most legumes and have proved useful in identifying new sources of variation. They may however not eliminate the need to evaluate entire collections, particularly for very rare traits. Molecular characterization and association mapping will further aid to insights into the structure of legume diversity and facilitate greater use of collections. The use of high resolution elevational climate models has greatly improved our capacity to characterize plant habitats and species?? adaptive responses to stresses. Evidence suggests that there has been increased use of wild relatives as well as new resources resulting from mutagenesis to enhance the genetic base of legume cultigens.  相似文献   

12.
The wavelet transform is a new subject developed quickly in the past ten years Compared with Fourier transform and Gabor transform, the wavelet transform is a part of time-frequency transform, so the message can be obtained from the signals effectively. By means of the fractionized multiresolution analysis to the signals, many problems unalbe to be solved by Fourier tranform have been solved in this way.Based on the fact that the maxima of the noise wavelet transform reduces dramatically with the increase of the scale, we obtain the result that this way is more advanced than the Fourier transform multiresolution analysis to the noise elimination.  相似文献   

13.
To solve the frequency dispersive feature in powerline channel, the quthors analyzed the anti-interference performance of modulation schemes with different subcarrier bases, and use orthogonal wavelet packet as subcarrier base instead of sine base in OFDM to suppress multi-path effect and frequency selective fading by its orthogonality in powerline channel. Through experiment, performances of wavelet packet modulation with different wavelet packets and OFDM are analyzed. Experiment results indicate that when the SNR has reached a certain level, orthogonal wavelet packet modulation has better performance than bi-orthogonal wavelet packet and sine base.  相似文献   

14.
While evaluating plant response to biotic or abiotic stress and genotype–environment interactions and searching causes of yield gap, very often are observed data with non‐normal distributions. One of the commonly encountered types of variables with a non‐normal distribution is count data. Count data are defined as the type of observations which have a positive, non‐zero, integer value. The selection of appropriate probability distributions and model types is very important due to the risk of estimating the variance incorrectly—the phenomenon of over‐dispersion. Increasingly, biologists and agronomists have been using methods based on generalized linear models. However, sometimes, when including count data, they are not aware of or disregard their over‐dispersion. One of the solutions for over‐dispersed count data is to use probability distributions and model types which assume a more flexible mean and variance relationship. Thus, the aim of this study is to present various ways of assessing over‐dispersion. Additionally, we present alternative distributions and discuss other approaches to solve the problem of over‐dispersion in count data sets. As examples in this study are used real data sets from different agricultural experiments. In our study, in one out of the two data sets used, this phenomenon occurred. Thus, in the analysis of count data, instead of using default distribution (usually Poisson distribution), other distributions should be considered because of the possible occurrence of over‐dispersion. We also observed that there is not one universal distribution to use and each data set might need a separate assessment to choose its distribution. For an efficient and proper count data analysis, with potential over‐dispersion, it is important to explore several options, i.e. evaluate models with an alternative to Poisson probability distributions and then make an informed choice.  相似文献   

15.
It's necessary to process position and gesture of rocket on real time within the flight of rocket. This work should base exact data. But much noise has been found in the data and the noise recognize is regarded as a focus. A speedy online arithmetic recognizing noise is proposed based on wavelet transform. The computing complexity measured by time of this arithmetic is a constant which is greatly reduces the works of calculation of wavelet transform. It can recognize the noise fast when the signal is gathered. The applications in these problems show that the effective arithmetic satisfies the needs of real time and can handle the real time data measured in other yields.  相似文献   

16.
Chongqing, the old industry base of China, whose main economic support is mass manufacturing that make up of traditional industries such as mechanism, enginery and metallurgy. This mass has come into being middle system organizations whose core is some big firms like Changan and Jialing, in addition, many related kit factories act as branches. These organizations have agility operation and high efficiency, but there are problems because of technology asymmetry which leads to low efficiency of the industry gathers supply chain when facing high informationization market cornpetition. By analyzing the character and deficiency of the Chongqing manufacturing industry gathers, through providing a framework of information service platform to enhance the mid-rain enterprises innovation capability and complex competition. Research on building method and operation method of enterprises informationization platform has been done successfully.  相似文献   

17.
In this paper, the aims were (a) to test the usefulness of using genomic and phenotypic information from public databases (open access) to predict genetic values for tropical maize inbred lines regarding plant and ear height; (b) to identify how the population structure, the use of optimized training sets (OTSs) and the amount of information originating from public databases affect the predictive ability. Thus, 29 training sets (TSs) were defined considering three diversity panels: the University of São Paulo (USP—validation set (VS)) and the ASSO and USDA North Central Regional Plant Introduction Station (NCRPIS) (external public panels—predictors), which were divided into four scenarios with different TS configurations. We showed that it is possible to use public datasets as a primary TS and that population structure can modify the predictive abilities of GS. In the four scenarios proposed, very large or very small sets did not provide predictive abilities over 0.53 for GS. However, OTSs composed of 250 individuals were sufficient to achieve predictive abilities over this limit.  相似文献   

18.
A new automatic revised method of wafer profile error which uses CCD measuring error,sets up machining data base and carries out a wedge structure for stepless compensating error in honing process is described.Using this technology,a high precision LSI wafers can be obtained.  相似文献   

19.
In this paper,the four-moment reliability analysis method for perfopmance function implicit structure is discussed. Discrete formulas expressed by Gauss-quadrature are presented when determine the parameter of probability density function which is established based on maximum entropy theory. The method in this paper is proposed for performance function implicit structure. Particularly, the discrete formulas used in this paper largely reduce calculating work with the same precision, so that the time-consume problem of four-moment reliability anlaysis is solved.  相似文献   

20.
This paper introduces the comprehensive hydraulic testing set for many kinds of hydraulic elements with hydraulic drive, hydraulic regulation and hydraulic loading. It has rational structure compact arrangement, reliable characteristics and advanced technique. In order to reduce the energy loss in the hydraulic system of the testing set, 1 ad sensing control is used. The static and dynamic characteristics of the load sensing system are analysed with the method of numeral simulation on computer. the testing witk load sensing control results show energy may be saved obviously and the heat load in hydraulic system may be reduced effectively, then testing quality is improved and the volume cf oil case is lessened. The lead sensing valve design is satisfied with simplifying structure so that it may be used reliably for the fixed flow hydraulic system of the testing set or other machines.  相似文献   

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