Showing papers by "Southwest University of Science and Technology published in 2004"

A Non-parametric Wavelet Feature Extractor for Time Series Classification

Abstract: Many representation schemes for time series have been proposed and most of them require predefined parameters. In case of classification, the accuracy is considerably influenced by these predefined parameters. Also, the users usually have difficulty in determining the parameters. The aim of this paper is to develop a representation method for time series that can automatically select the parameters for the classification task. To this end, we exploit the multi-scale property of wavelet decomposition that allows us to automatically extract features and achieve high classification accuracy. Two main contributions of this work are: (1) selecting features of a representation that helps to prevent time series shifts, and (2) choosing appropriate features, namely, features in an appropriate wavelet decomposition scale according to the concentration of wavelet coefficients within this scale.

Research on the detecting algorithm of text document information hiding

Abstract: This paper put emphasis on vulnerability analyses based on semantic algorithm of text document information hiding aiming at popular algorithms of text document information hiding, and then designed a universally detecting algorithm named a detecting algorithm to measure relativity between sentences by the idea of conceptual graph Experimental result shows that the detecting algorithm can achieve a high degree of detecting reliability

Performances of concrete under elevated curing temperature

Abstract: The behaviors of concrete at elevated curing temperature were studied. The test results show that when concrete is cured at elevated temperature, a harmful consequence occurs. The later strength decreses significantly compared to that under normal curing condition. Incorporating silica fume, fly ash and slag or lowering w/c ratio can effectively alleviate this harmful consequence. Comparatively, incorporation of silica fume is the most efficient means to decrease the later strength reduction. The harmful consequence is not caused by the difference in degree of hydration since the degree of hydration is similar between elevated curing temperature and normal curing condition. The SEM analysis shows that it is the uneven distribution of hydration products caused by elevated curing temperature that leads to the later strength reduction of concrete.

Low-temperature synthesis and characterization of GaN nanocrystals from gallium trichloride precursor

Abstract: Gallium nitride (GaN) has been synthesized by reacting gallium trichloride with ammonia (NH(3)) at low temperatures ranging from 500 to 1000 degreesC for 12 h. X-ray diffraction, transmission electron microscopy, infrared, and Raman backscattering spectra revealed that the synthesized GaN powder consists of single-phase nano-sized crystallites with the wurtzite-type structure. The average size of the crystals decreases with the reaction temperature from approximately similar to63 nm at 1000 degreesC to similar to5 nm at 500 degreesC. GaOCl and epsilon-Ga(2)O(3) are the intermediate products during synthesis of the GaN. Characteristic shifts of the Raman peaks are associated with the change in crystal size. The band-edge emission of GaN at 361 nm was observed on room temperature photoluminescence spectra exclusively for the sample synthesized at 1000 degreesC, while a new and broad emission band appeared with the center ranging from 827 to 765 nm for the samples synthesized between 500 and 800 degreesC.

A calculation method of earth pressure considering displacement

Abstract: According to Rankine抯 theory of earth pressure, and analysis of relationship between active and passive and static earth pressure and displacement of retaining wall, an approximate calculation method of earth pressure considering displacement is presented. The rule of earth pressure varying with displacement presented in this paper is well comparable with the results of the finite element analysis.

The Effect of the Total Saponin Extract from the Shoots of Momordica Charantia L. on Anti-virus HSV-II Activity

Abstract: The effects of the total saponin extract from the shoots of Momordica charantia L. on in vitro cell showed that no cell toxicity was observed at concentrations from 0.005～500(×10-6g/mL),while anti-virus HSV-Ⅱ activity was detected to certain degree at concentrations of 62.5(×10-6g/mL).

Study on graphite electrically conductive concrete

Abstract: The changes of resistance are discussed during 28 days conservation in this parer.The resisitance obtained by DC and AC and digital multimeter is compared.The changes of the resistance and 28 days compressive strength along with graphite contents are analyzed,and the critical content is confirmed.

The research of signal processing technique of continuous wave radar altimeter

Abstract: This research aims at promoting the survey accuracy of a continuous wave radar altimeter An adaptive signal processing technique for the CW radar altimeter is the core of the research The research means and techniques for realizing adaptive anti-jamming, and how to achieve adaptive cancelling of the revealed signal of the projector are introduced in detail The system structure, working principle and algorithm derivation are also presented The research and application pave way for the technological transformation of the next generation of continuous wave radar altimeters

Study Status on Degradable Mulching Film

Abstract: The development status of degradable mulching film is introduced. The development problems of degradable mulching film are pointed out, and its development trends are analyzed. The conclusion shows that degradable mulching film is still at experimental and extending stage due to the limitations of technology, ligh cost and general recognizations. In any case,the use of degradable mulching film is a good way to solve the problem of "white pollution" and promises a wide market foreground.

Microbial Hydrolyzing of Lignin

Abstract: In this paper, review is given on the lignin degrading enzyme system and the regulating and controlling measures of activity of enzyme, the mechanism of lignin-biodegrading and applications of lignin degrading enzyme system are discussed.

An information sharing structure of broadcasting

Abstract: The architecture design is the basis for constructing the grid system. Based on the existing grid technologies, the dilemma of grid technology is analyzed. The new architecture of broadcasting grid is built in view of information sharing theory and Scale-Free Networks, and the sandglass pattern is drawn up. The results of simulation demonstrate the feasibility and validity of the architecture in DVB-C networks for distance educations. Also, the satellite channel experiments results verify its value by China Education Television Station (CETV).

Analysis of mud-slag of calcium carbide

Abstract: Mud-slag, discharged from the hydrolysis of calcium carbide to produce acetylene, contains large amounts of calcium oxide and small amounts of silicon, iron, aluminum, magnesium and carbon residue. An over-all analysis of such mud-slag is described containing the following items: ① Free water in the sample was determined by drying the sample at 60～80℃ for 30min, and then at 105～110℃ for 2h. The loss in weight, before and after drying represents the content of free water. ② Based on the result of differential thermal analysis combined water in the sample was determined by the loss in weight of the dried sample before and after the ignition at 580～600℃ for 2h. ③ Determinations of Fe、 Al、 Ca、 Mg and Si were carried out according to the procedures mentioned in reference [1] of this paper. ④ Ignition loss of the sample was determined by the loss in weight of the dried sample before and after ignition at 1 000℃ for 40min.

The Surface Groups and Active Site of Fibrous Mineral Materials

Abstract: The exposed and transformed groups of fibrous brucite, wollastonite, chrysotile asbestos, sepiolite, palygorskite, clinoptilolite, crocidolite and diatomaceous earth mineral materials are analyzed by IR spectra after acid and alikali etching, strong mechanical and polarity molecular interaction. The results show the active sites concentrate on the ends in stick mineral materials and on the defect or hole edge in pipe mineral materials. The inside active site of mineral materials plays a main role in small molecular substance. The shape of minerals influence their distribution and density of active site. The strong mechanical impulsion and weak chemical force change the active site feature of minerals, the powder process enables minerals exposed more surface group and more combined types. The surface processing with the small polarity molecular or the brand of middle molecular may produce ionation and new coordinate bond, and change the active properties and level of original mineral materials.

Performance Research on Carbon Fiber Conductive Concrete

Abstract: The carbon fiber conductive concrete is prepared in CF elementary material of function. The changes of the resistivity and 28 days compressive strength with carbon fiber contents and the resistivity variation with the voltage of AC power are analyzed. The electro-thermal efficiency is analyzed under the different voltages and accounted approximately by a trend numeration. The experimental results show that the critical content in volume of CF is 1.0%. The resistivity decreases with the increasing of voltage. The thermal energy produced in CFRC connected to AC power source is enough for deicing and snow melting purpose. Thermal transformation efficiency of CFRC is up to 99.5% by the trend numeration.

Design of USB's Equipment Driver Based on Windows

Abstract: The paper introduces the design method of USB's equipment driver based on Windows.Through discussion and application to WDM's driver design method,the computer communication is realized with EZ-USB's chip.

A Life Prediction Model for Nickel-Base Single Crystal Superalloy DD3

Abstract: The possibility of the life prediction model for nickel-base single crystal blades has been studied. The fatigue-creep (FC) and thermal fatigue-creep (TMFC) as well as creep experiments have been carried out with different hold time of DD3. The hold time and the frequency as well as the temperature range are the main factors influencing on the life. An emphasis has been put on the micro mechanism of the rupture of creep, FC and TMFC. Two main factors are the voiding and degeneration of the material for the creep, FC and TMFC experiments. There are voids in the fracture surfaces, and size of the voids is dependent on the loading condition. Generally, the rupture mechanism is the same for creep, FC and TMFC. If the loading can be simplified to the working conditions of the turbine blades, i.e. the hold time is at the top temperature and maximum stress, a linear life model is satisfactory to the life prediction of nickel-base single crystal superalloy from the experimental study in this paper. The temperature and the stress level of the nickel-base single crystal (SC)blades are not uniform. To predict the life of SC blades, one should consider the cycles of the temperature and stress as well as the oxidation simultaneously. In the past 30 years, there are many works on the mechanical behavior and description, such as the inelastic constitutive relationships, plastic, fracture, isothermal creep and fatigue and thermal fatigue as well as oxidation [1-3]. There are also special software (program) to analyze the deformation and life of nickel-base single crystal structures, such as blades. In order to apply to the engineering more conveniently, there should be a life prediction model for the blades. The model should not be too complex, but take more influential factors as possible into consideration.

Processing Word Documents with Visual Basic 6.0

Abstract: By using ActiveX components of Visual Basic 6.0,its support to the object library of Microsoft Word,and VBA functions embedded in Microsoft Word,the paper realizes the combination of several Word documents and once automatic filling with common content in order to accomplish the high efficient treatment of Word document.

Design and Realization of CA Server in PKI System

Abstract: Public Key Infrastructure(PKI) is one of the important techniques for solving network security problem.The typical PKI application system includes security Web server,Registration Authority(RA)server,Certificate Authority(CA)server,LDAP server and database server.As a kernel entity in PKI system,CA server acts the important functions of issues,managing and revoking certificates.By analyzing the structure of PKI message,this paper brings forward the principle of designing CA server based on multithreading scheme and describes the process of message alternation between CA and RA.

Encoding and Decoding Method for Infrared Remote-control Signal

Abstract: In detail introduced an encoding and decoding method for infrared remote-control signal with software of microchip,infrared signal was received by HS0038 whose frequency is 38 kHz,including principle of encoding and modulation and decoding,hardware circuit whose center was AT89C2051 and programTransmission of infrared remote-control signal based on byte was realizedIts experiment indicates that the method can benefit to reliable transmission of infrared remote-control signal,distance of transmission could reach 15 m,speed of transmission could reach (1 200) bit/s if number of the pulse of encoding would be reduced properlyThe method could be used to computer control system