Wavelet neural network possesses the best function approximation ability, that is to say it has the ability to identify the model. Because the constricting model algorithm is different from common artificial neural network BP algorithm, it can effectively overcome intrinsic defect of common artificial neural network. Therefore the better prediction effect can be reached effectively. The paper gives a method of prediction model of chaotic time series based on wavelet neural network that enables prediction model to have not only wavelet good approximation property, but also neural network self-learning adaptive quality. The authors make use the method to predict sea clutter data.
The pipeline is widely used in various kinds of mechanical equipment, usually fixed by the clamps. It is great important to detect the fixed clamps for the operation of equipment by signal processing. The time domain signal is quite popular in the field of signal processing. There are generally two major types of methods for analyzing time-domain signals. The one is that the time domain signal is converted into other domains such as frequency domain and time frequency domain; the other is using statistical analysis methods to analyze signals. This paper presents a new feature extraction method based on statistical analysis, which is called the number of conformation patterns (CPN). The phase space reconstruction of time series is carried out, and the numbers of conformation patterns with different embedding dimensions are counted to be features for the signal. Through the simulation analysis, the characteristic values are sensitive to the frequency of the signal. This method is used to analyze the experimental data of the looseness of the pipeline clamp, and the results show that CPN can effectively detect the different degrees of clamp looseness.
Analytical and numerical solutions of the Schroedinger Equation which was satisfied by the propagator P(b, a) , including all the paths contribution, are discussed. The definition of Schrödinger transform of image is first proposed. Exterior and interior of objects are obtained from Schroedinger transforms of original image and its inverse image. Using the bruteforce algorithm, sets of exterior and interior points are thinned. By finding pairs of exterior and interior points with the smallest distance between them, contours of multiple objects are extracted. Some experiments with simulated and real images are given.
In this paper,the adsorption capacity of loess for mineral oils and the influence of temperature,pH,organic matter content and salt contents on the adsorption were investigated by laboratory static experiments.The results showed that adsorption of oils on loess conforms to Langmuir isotherm.Adsorption capacity decreased with the increase of temperature and pH.Adsorption tended to increase with the decrease of diameter of soil particles.There was a positive linear correlation between the adsorption and the organic matter content or salt contents.With the organic matter content and salt content increasing,the adsorption increased.
This article focuses on stepper motor control, and introduces the hardware structure of position control system design based on LabVIEW. Steps and methods of software design are expounded emphatically, and then test data are given. Tests show that the system has small steady-state error, short adjusting time, friendly interface, excellent portability, good control effect and other characteristics.
In order to improve the lightning withstand level of transmission lines, to reduce line lightning trip-out rate and the accident rate, to improve power supply reliability, grounding resistance in grounding grid of transmission line tower should be effectively ameliorated. As to the transmission line tower grounding grid in the plateau mountainous with thin soil, dry soil and complex geological conditions, the grounding electrode landfill layer is shallow and grounding resistance is significantly higher. Improvement of grounding grid and application of special resistance reducing material can reduce the the grounding resistance effectively. This technology has been applied to an actual construction reformation of transmission line tower grounding grid. The comparison of the test results verifies that grounding resistance can be effectively reduced by using a combination of above methods in complex geological environment.
Abstract Open-path eddy covariance systems are widely used for measuring the CO 2 flux between land and atmosphere. A common problem is that they often yield negative fluxes or physiologically unreasonable CO 2 uptake fluxes in the nongrowing season under cold conditions. In this study, a meta-analysis was performed on the eddy flux data from 64 FLUXNET sites and the relationship between the observed CO 2 flux and the sensible heat flux was analyzed. In theory, these two fluxes should be independent of each other in cold conditions (air temperature lower than 0°C) when photosynthesis is suppressed. However, the results show that a significant and negative linear relationship existed between these two fluxes at 37 of the sites. The mean linear slope value is −0.008 ± 0.001 µ mol m −2 s −1 per W m −2 among the 64 sites analyzed. The slope value was not significantly different among the three gas analyzer models (LI-7500, LI-7500A, IRGASON/EC150) used at these sites, indicating that self-heating may not be the only reason for the apparent wintertime net CO 2 uptake. These results suggest a systematic bias toward larger carbon uptakes in the FLUXNET sites that deploy open-path eddy covariance systems.
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