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Study of Pyrolysis Characteristics and Kinetic Analysis of Shenmu Coal at a High Heating Rate Using TG-FTIR
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作者 An Xiaoxi Zhang Yanpeng +2 位作者 Shang Yanchao Tian Yuanyu Qiao Yingyun 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2024年第1期47-55,共9页
Coal pyrolysis is a fundamental reaction in the thermal processing and utilization of coal.Investigating the behavior and kinetics of coal pyrolysis is crucial for optimizing,designing,and developing a composite riser... Coal pyrolysis is a fundamental reaction in the thermal processing and utilization of coal.Investigating the behavior and kinetics of coal pyrolysis is crucial for optimizing,designing,and developing a composite riser for the staged pyrolysis gasification process of pulverized coal.In this study,the non-isothermal pyrolysis behavior and kinetics of coal were examined at different heating rates(30,50,100,300,500,700,and 900℃/min)using thermogravimetry(TG)coupled with Fourier-transform infrared spectroscopy.Analysis of the TG/derivative TG(TG/DTG)curves indicated that coal pyrolysis mainly occurred between 300℃ and 700℃.Higher heating rates led to more volatiles being released from the coal,and a higher temperature was required to achieve rapid pyrolysis.Kinetic analysis showed that both the model-free methods(Friedman,Flynn-Wall-Ozawa,and Kissinger-Akahira-Sunose)and the model-based method(Coats-Redfern)effectively describe the coal pyrolysis process.The change in the Ea values between the two kinetic models was consistent throughout the pyrolysis process,and the most probable mechanism was the F2 model(secondary chemical reaction).In addition,the heating rate did not change the overall reaction order of the pyrolysis process;however,a higher heating rate resulted in a decrease in the Ea value during the initial pyrolysis stage. 展开更多
关键词 coal pyrolysis TG-FTIR characteristic parameters DYNAMICS
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Optical remote sensing image characteristics of large amplitude convex mode-2 internal solitary waves:an experimental study
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作者 Zhixin Li Meng Zhang +1 位作者 Keda Liang Jing Wang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第6期16-23,共8页
A series of experiments are designed to propose a new method to study the characteristics of convex mode-2internal solitary waves(ISWs)in optical remote sensing images using a laboratory-based optical remote sensing s... A series of experiments are designed to propose a new method to study the characteristics of convex mode-2internal solitary waves(ISWs)in optical remote sensing images using a laboratory-based optical remote sensing simulation platform.The corresponding wave parameters of large-amplitude convex mode-2 ISWs under smooth surfaces are investigated along with the optical remote sensing characteristic parameters.The mode-2 ISWs in the experimentally obtained optical remote sensing image are produced by their overall modulation effect on the water surface,and the extreme points of the gray value of the profile curve of bright-dark stripes appear at the same location as the real optical remote sensing image.The present data extend to a larger range than previous studies,and for the characteristics of large amplitude convex mode-2 ISWs,the experimental results show a second-order dependence of wavelength on amplitude.There is a close relationship between optical remote sensing characteristic parameters and wave parameters of mode-2 ISWs,in which there is a positive linear relationship between the bright-dark spacing and wavelength and a nonlinear relationship with the amplitude,especially when the amplitude is very large,there is a significant increase in bright-dark spacing. 展开更多
关键词 mode-2 internal solitary waves optical remote sensing characteristic parameter wave characteristic
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PREDICTION OF PUMP CHARACTERISTICS ACCORDING TO GEOMETRICAL PARAMETERS OF IMPELLER AND VOLUTE CASING
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作者 Wei Guangxin Guan Xingfan +1 位作者 Guo Nailong Huang Daojian(Jiangsu University of Science and Technology) 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 1995年第4期272-277,共17页
The geometrical parameters of impeller or volute casing (including guide vane ofmultistage pump) have a great effect on pump characteristics, but ultimately. the pump characteris-tics are determined by the geometrical... The geometrical parameters of impeller or volute casing (including guide vane ofmultistage pump) have a great effect on pump characteristics, but ultimately. the pump characteris-tics are determined by the geometrical parameters of impeller and volute casing cooperatively. Inthis essay the effect of impeller and volute casing on pump characteristics will be studiedquantitatvely from the angle cf optimal matching of them. 展开更多
关键词 Pump characteristics Impeller Volute casing Geometrical parameter Predic-tion
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Self-heating tendency evaluation of sulfide ores based on nonlinear multi-parameters fusion 被引量:1
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作者 潘伟 吴超 +1 位作者 李孜军 杨月平 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第2期582-589,共8页
In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials ... In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials and their self-heating characteristics were measured in laboratory. Furthermore, the measured temperature was studied by integrating wavelet transform, nonlinear characteristic parameters extraction and fuzzy comprehensive evaluation. The results indicate that only the ore samples 1, 2, 6 and 9 have obvious self-heating phenomenon, and their self-heating initiative temperatures are 220 ℃, 239 ℃, 220 ℃ and 220 ℃, respectively, which means that they are difficult to produce self-heating under normal mining conditions. The correlation dimension of self-heating process is fraction and the maximum Lyapunov exponent is positive, which means that it is feasible to study the self-heating process based on chaotic dynamics theory. The nonlinearities of self-heating process of these four samples (ore samples 1, 2, 6 and 9) are 0.8227, 0.7521, 0.9401 and 0.8827 respectively and the order of the samples according to these results is: sample 6, sample 9, sample 1, sample 2, which is consistent with the measured results of self-heating characteristics. Therefore, the nonlinearity method can be used to evaluate the self-heating tendency of sulfide ores, and it is an effective verification of the reliability of measured results. 展开更多
关键词 sulfide ores self-heating process nonlinear characteristic parameter NONLINEARITY self-heating tendency
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Dynamic Characteristics Analysis and Vibration Experiment of Upper-time of Flight Counter (U-ToFC) 被引量:3
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作者 WU Qiong ZHANG Yidu SONG Sunguang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2012年第5期868-874,共7页
The dynamic characteristic parameters of Up-time of Flight Counter (U-ToFC) are important for research of structure optimization and reliability. However, the current simulation is performed based on homogenous mate... The dynamic characteristic parameters of Up-time of Flight Counter (U-ToFC) are important for research of structure optimization and reliability. However, the current simulation is performed based on homogenous material and simplified constraint model, the correct and reliability of results are difficult to be guaranteed. The finite element method based on identification of material parameters is proposed for this investigation on dynamic analysis, simulation and vibration experiment of the U-ToFC. The structure of the U-ToFC is complicated. Its' outside is made of aluminum alloy and inside contains electronic components such as capacitors, resistors, inductors, and integrated circuits. The accurate material parameters of model are identified difficultly. Hence, the parameters identification tests are performed to obtain the material parameters of this structure. On the basis of the above parameters, the experiment and FEA are conducted to the U-ToFC. In terms of the flight acceptance test level, and two kinds of joints condition between the U-ToFC and fixture are considered. The natural frequencies, vibration shapes and the response of the power spectral density of the U-ToFC are obtained. The results show simulation which is based on parameters identification is similar with vibration experiment in natural frequencies and responses. The errors are less than 10%. The vibration modes of simulation and experiment are consistent. The paper provides a more reliable computing method for the dynamic characteristic analysis of large complicated structure. 展开更多
关键词 random vibration dynamical characteristic parameters finite element analysis identification of material parameters
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Prestack seismic stochastic inversion based on statistical characteristic parameters 被引量:3
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作者 Wang Bao-Li Lin Ying +1 位作者 Zhang Guang-Zhi Yin Xing-Yao 《Applied Geophysics》 SCIE CSCD 2021年第1期63-74,129,共13页
In the conventional stochastic inversion method,the spatial structure information of underground strata is usually characterized by variograms.However,effectively characterizing the heterogeneity of complex strata is ... In the conventional stochastic inversion method,the spatial structure information of underground strata is usually characterized by variograms.However,effectively characterizing the heterogeneity of complex strata is difficult.In this paper,multiple parameters are used to fully explore the underground formation information in the known seismic reflection and well log data.The spatial structure characteristics of complex underground reservoirs are described more comprehensively using multiple statistical characteristic parameters.We propose a prestack seismic stochastic inversion method based on prior information on statistical characteristic parameters.According to the random medium theory,this method obtains several statistical characteristic parameters from known seismic and logging data,constructs a prior information model that meets the spatial structure characteristics of the underground strata,and integrates multiparameter constraints into the likelihood function to construct the objective function.The very fast quantum annealing algorithm is used to optimize and update the objective function to obtain the fi nal inversion result.The model test shows that compared with the traditional prior information model construction method,the prior information model based on multiple parameters in this paper contains more detailed stratigraphic information,which can better describe complex underground reservoirs.A real data analysis shows that the stochastic inversion method proposed in this paper can effectively predict the geophysical characteristics of complex underground reservoirs and has a high resolution. 展开更多
关键词 prior information random medium theory statistical characteristic parameters stochastic inversion very fast quantum annealing
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Synthetically quantitative evaluation function of characteristic parameters on CO_2 arc welding process 被引量:4
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作者 俞建荣 蒋力培 +2 位作者 史耀武 孙振国 王军波 《China Welding》 EI CAS 2001年第1期19-26,共8页
The statistical probability and their variation regularity of the measurable characteristic parameters in the CO 2 arc welding droplet short circuiting transfer process have been studied. The statistical analysis sh... The statistical probability and their variation regularity of the measurable characteristic parameters in the CO 2 arc welding droplet short circuiting transfer process have been studied. The statistical analysis shows that the sensitivity of each characteristic parameter with regard to the variation of the short circuiting transfer process is different. The sensitivity of 4 kinds among these characteristic parameters is more intense than that of the short circuiting transfer frequency. In order to take account of the synthetic influence of these characteristic parameters, by means of the characteristic parameters synthetic value, a quantitative evaluation function is built up to describe and evaluate the short circuiting transfer process of CO 2 arc welding in real time. The testing shows that the evaluation function can give a suitable synthetic valuation for the short circuiting transfer process with a variety of welding variables. 展开更多
关键词 CO 2 arc welding process characteristic parameters quantitative evaluation function
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Wind Wave Characteristics and Engineering Environment of the South China Sea 被引量:4
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作者 WANG Zhifeng ZHOU Liangming +4 位作者 DONG Sheng WU Lunyu LI Zhanbin MOU Lin WANG Aifang 《Journal of Ocean University of China》 SCIE CAS 2014年第6期893-900,共8页
Wave simulation was conducted for the period 1976 to 2005 in the South China Sea (SCS) using the wave model, WAVEWATCH-III. Wave characteristics and engineering environment were studied in the region. The wind input... Wave simulation was conducted for the period 1976 to 2005 in the South China Sea (SCS) using the wave model, WAVEWATCH-III. Wave characteristics and engineering environment were studied in the region. The wind input data are from the objective reanalysis wind datasets, which assimilate meteorological data from several sources. Comparisons of significant wave heights between simulation and TOPEX/Poseidon altimeter and buoy data show a good agreement in general. By statistical analysis, the wave characteristics, such as significant wave heights, dominant wave directions, and their seasonal variations, were discussed. The largest significant wave heights are found in winter and the smallest in spring. The annual mean dominant wave direction is northeast (NE) along the southwest (SW)-NE axis, east northeast in the northwest (NW) part of SCS, and north northeast in the southeast (SE) part of SCS. The joint distributions of wave heights and wave periods (directions) were studied. The results show a single peak pattern for joint significant wave heights and periods, and a double peak pattern for joint significant wave heights and mean directions. Furthermore, the main wave extreme parameters and directional extreme values, particularly for the 100-year return period, were also investigated. The main extreme values of significant wave heights are larger in the northern part of SCS than in the south- ern part, with the maximum value occurring to the southeast of Hainan Island. The direction of large directional extreme Hs values is focus in E in the northem and middle sea areas of SCS, while the direction of those is focus in N in the southeast sea areas of SCS. 展开更多
关键词 surface waves statistical characteristics joint distributions extreme parameters
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The influence of MoS_2 on tribology characteristic parameter of Ni60A/MoS_2 composite lubricating coating 被引量:1
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作者 ZHAO Yun-cai GE Shi-rong 《Journal of Coal Science & Engineering(China)》 2010年第1期94-98,共5页
The influence of MoS2 on the tribology characteristic parameter of Ni60A/MoS2 composite lubricating coating was researched on the UMT-2 fretting abrasion tester (USA) The result shows that with increasing content of... The influence of MoS2 on the tribology characteristic parameter of Ni60A/MoS2 composite lubricating coating was researched on the UMT-2 fretting abrasion tester (USA) The result shows that with increasing content of MoS2, the hardness curve of the composite coating decreases and the trend accelerates. Under the same experimental conditions, the mass loss of plasma spray composite coating without adding MoS2 iS 1.27×10^-2 mg. When the amount of MoS2 reaches 35%, the mass loss is 0.96×10^-2 mg. It can be seen that adding MoS2 phase can improve the wear resistance, the amplitude of which is close to 30%. The friction coefficient of plasma spray composite coating without adding MoS2 is 0.23. Adding MoSz could decrease the friction coefficient of the coating and presents a downtrend. When the mass fraction is 35%, the friction coefficient is the smallest (0.13), and the range is doubled. 展开更多
关键词 plasma spraying MoS2 phase composite lubricant coating tribology characteristic parameter friction coefficient
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Some Characteristic Parameters of the Basic Components of the Solar Radio Emission 被引量:1
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作者 Ji Shuchen (Beijing Astronomical Observatory, The Chinese Academy of Sciences, Beijing 100080, China) (Yunnan Observatory, The Chinese Academy of Sciences, Kunming 650011, China) (National Astronomical Observatories, The Chinese Academy of Sciences) $$ 《天文研究与技术》 CSCD 1999年第S1期457-460,共4页
Four basic components of the solar radio emission: the quiet sun, the slowly varying component (SVC), the radio burst and the ultra-fast varying component (UFVC) are studied. As their six characteristic parameters: ra... Four basic components of the solar radio emission: the quiet sun, the slowly varying component (SVC), the radio burst and the ultra-fast varying component (UFVC) are studied. As their six characteristic parameters: radiation source, brightness temperature, radiation lifetime, polarized radiation, radiation mechanism, and character of superposition are affirmed. 展开更多
关键词 RADIO Some Characteristic parameters of the Basic Components Basic of the Solar Radio Emission
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The microwave scattering characteristics of sea ice in the Bohai Sea 被引量:2
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作者 LIU Meijie DAI Yongshou +4 位作者 ZHANG Jie ZHANG Xi MENG Junmin ZHU Xiuqin YIN Yalei 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2016年第5期89-98,共10页
Microwave remote sensing has become the primary means for sea-ice research, and has been supported by a great deal of field experiments and theoretical studies regarding sea-ice microwave scattering. However, these st... Microwave remote sensing has become the primary means for sea-ice research, and has been supported by a great deal of field experiments and theoretical studies regarding sea-ice microwave scattering. However, these studies have been barely carried in the Bohai Sea. The sea-ice microwave scattering mechanism was first developed for the thin sea ice with slight roughness in the Bohai Sea in the winter of 2012, and included the backscattering coefficients which were measured on the different conditions of three bands(L, C and X), two polarizations(HH and VV), and incident angles of 20° to 60°, using a ground-based scatterometer and the synchronous physical parameters of the sea-ice temperature, density, thickness, salinity, and so on. The theoretical model of the sea-ice electromagnetic scattering is obtained based on these physical parameters. The research regarding the sea-ice microwave scattering mechanism is carried out through two means, which includes the comparison between the field microwave scattering data and the simulation results of the theoretical model, as well as the feature analysis of the four components of the sea-ice electromagnetic scattering. It is revealed that the sea-ice microwave scattering data and the theoretical simulation results vary in the same trend with the incident angles. Also, there is a visible variant in the sensitivity of every component to the different bands.For example, the C and X bands are sensitive to the top surface, the X band is sensitive to the scatterers, and the L and C bands are sensitive to the bottom surface, and so on. It is suggested that the features of the sea-ice surfaces and scatterers can be retrieved by the further research in the future. This experiment can provide an experimental and theoretical foundation for research regarding the sea-ice microwave scattering characteristics in the Bohai Sea. 展开更多
关键词 sea-ice field experiment sea-ice microwave scattering characteristics sea-ice physical parameters sea-ice electromagnetic scattering theory
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Characteristic parameters of electromagnetic signals from a human heart system
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作者 刘新元 裴留庆 +3 位作者 王寅 张素明 高红蕾 戴远东 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第4期456-464,共9页
The electromagnetic field of a human heart system is a bioelectromagnetic field. Electrocardiography (ECG) and magnetocardiography (MCG) are both carriers of electromagnetic information about the cardiac system, a... The electromagnetic field of a human heart system is a bioelectromagnetic field. Electrocardiography (ECG) and magnetocardiography (MCG) are both carriers of electromagnetic information about the cardiac system, and they are nonstationary signals. In this study, ECG and MCG data from healthy subjects are acquired; the MCG data are captured using a high-Tc radio frequency superconducting quantum interference device (HTc rf SQUIDs) and the QRS complexes in these data are analysed by the evolutionary spectrum analysis method. The results show that the quality factor Q and the central frequency fz of the QRS complex evolutionary spectrum are the characteristic parameters (CHPs) of ECG and MCG in the time-frequency domain. The confidence intervals of the mean values of the CHPs are estimated by the Student t distribution method in mathematical statistics. We believe that there are threshold ranges of the mean values of Q and fz for healthy subjects. We have postulated the following criterion: if the mean values of CHPs are in the proper ranges, the cardiac system is in a normal condition and it possesses the capability of homeostasis. In contrast, if the mean values of the CHPs do not lie in the proper ranges, the homeostasis of the cardiac system is lacking and some cardiac disease may follow. The results and procedure of MCG CHPs in the study afford a technological route for the application of HTc rf SQUIDs in cardiology. 展开更多
关键词 bioelectromagnetic field MAGNETOCARDIOGRAPHY ELECTROCARDIOGRAPHY characteristic parameters threshold ranges
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Numerical Analysis of the Nonlinear Parameterization of Waves in Currents over a Submerged Sill with a Non-Hydrostatic Model
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作者 MA Xlaozhou MA Yuxiang +1 位作者 GAO Yunpeng DONG Guohai 《Journal of Ocean University of China》 SCIE CAS CSCD 2017年第4期689-696,共8页
An investigation of the effects of a uniform current strength direction(following or opposing wave propagation) on the nonlinear transformation of irregular waves over a submerged trapezoidal sill is carried out using... An investigation of the effects of a uniform current strength direction(following or opposing wave propagation) on the nonlinear transformation of irregular waves over a submerged trapezoidal sill is carried out using SWASH,a non-hydrostatic numerical wave model.The nonlinear parameters(i.e.,asymmetry,skewness,and kurtosis) are calculated,and the empirical formulas for these parameters are presented as a function of the local Ursell number based on the present numerical data measured.In the shoaling area of the submerged sill,the nonlinear characteristics of waves are more obvious when waves propagate in the same direction as the currents than when waves propagate in the opposite direction.Whereas nonlinear parameters grow with the strengthening of the following currents over the crest,they tend to decrease as the adverse current velocity increases over the crest area of the submerged sill. 展开更多
关键词 wave-current interaction shallow water nonlinear characteristic parameters non-hydrostatic water-current model
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Estimations of Land Surface Characteristic Parameters and Turbulent Heat Fluxes over the Tibetan Plateau Based on FY-4A/AGRI Data
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作者 Nan GE Lei ZHONG +5 位作者 Yaoming MA Yunfei FU Mijun ZOU Meilin CHENG Xian WANG Ziyu HUANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2021年第8期1299-1314,共16页
Accurate estimates of land surface characteristic parameters and turbulent heat fluxes play an important role in the understanding of land-atmosphere interaction. In this study, Fengyun-4A (FY-4A) Advanced Geostationa... Accurate estimates of land surface characteristic parameters and turbulent heat fluxes play an important role in the understanding of land-atmosphere interaction. In this study, Fengyun-4A (FY-4A) Advanced Geostationary Radiation Imager (AGRI) satellite data and the China Land Data Assimilation System (CLDAS) meteorological forcing dataset CLDAS-V2.0 were applied for the retrieval of broadband albedo, land surface temperature (LST), radiation flux components, and turbulent heat fluxes over the Tibetan Plateau (TP). The FY-4A/AGRI and CLDAS-V2.0 data from 12 March 2018 to 30 April 2018 were first used to estimate the hourly turbulent heat fluxes over the TP. The time series data of in-situ measurements from the Tibetan Observation and Research Platform were divided into two halves-one for developing retrieval algorithms for broadband albedo and LST based on FY-4A, and the other for the cross validation. Results show the root-mean-square errors (RMSEs) of the FY-4A retrieved broadband albedo and LST were 0.0309 and 3.85 K, respectively, which verifies the applicability of the retrieval method. The RMSEs of the downwelling/upwelling shortwave radiation flux and downwelling/upwelling longwave radiation flux were 138.87/32.78 W m^(−2) and 51.55/17.92 W m^(−2), respectively, and the RMSEs of net radiation flux, sensible heat flux, and latent heat flux were 58.88 W m^(−2), 82.56 W m^(−2) and 72.46 W m^(−2), respectively. The spatial distributions and diurnal variations of LST and turbulent heat fluxes were further analyzed in detail. 展开更多
关键词 FY-4A/AGRI land surface characteristic parameters turbulent heat fluxes Surface Energy Balance System model Tibetan Plateau
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Research on the adjustment model of ventilation characteristic parameters based on integrated method of circuit and path
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作者 Ting-gui JIA Shu-gang WANG +1 位作者 Guo-na QU Jian LIU 《Journal of Coal Science & Engineering(China)》 2013年第1期33-37,共5页
Ventilation characteristic parameters are the base of ventilation network solution; however, they are apt to be affected by operating errors, reading errors, airflow stability, and other factors, and it is difficult t... Ventilation characteristic parameters are the base of ventilation network solution; however, they are apt to be affected by operating errors, reading errors, airflow stability, and other factors, and it is difficult to obtain accurate results. In order to check the ventilation characteristic parameters of mines more accurately, the integrated method of circuit and path is adopted to overcome the drawbacks caused by the traditional path method or circuit method in the digital debugging process of ventilation system, which can improve the large local error or the inconsistency between the airflow direction and the actual situation caused by inaccuracy of the ventilation characteristic parameters or checking in the ventilation network solution. The results show that this method can effectively reduce the local error and prevent the pseudo-airflow reversal phenomenon; in addition, the solution results are consistent with the actual situation of mines, and the effect is obvious. 展开更多
关键词 path method circuit method ventilation network adjustment model ventilation characteristic parameter
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Research on Characteristics of Reflection-type GaAs Optoelectronic Microwave Switching
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作者 胡正荣 《High Technology Letters》 EI CAS 1996年第2期31-33,共3页
In this paper the operation principle of the GaAs switch of the type of substrate-edge excitation is set forward, and the configuration parameters of the microstrip switch are designed. In the meantime, a method of pr... In this paper the operation principle of the GaAs switch of the type of substrate-edge excitation is set forward, and the configuration parameters of the microstrip switch are designed. In the meantime, a method of producing short pulses laser with high peak power is presented. The experimental results show that the insertion loss of the microwave switching is less than 1dB and the isolation is up to 30dB. 展开更多
关键词 Optoelectronic microwave switching Microstrip parameters Short pulse laser Characteristic parameters
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Testing Research about Characteristic Parameters of the Grounding Device at 750 kV Substation of Riyue Mountain,Qinghai
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作者 Chengshan Yang Yanjun Xin 《Meteorological and Environmental Research》 CAS 2013年第8期14-16,20,共4页
750 kV substation of Riyue Mountain, Qinghai is a substation that annual average thunderstorm days are the maximum at the same volt- age level and altitude in the wodd. We detailedly described testing methods and step... 750 kV substation of Riyue Mountain, Qinghai is a substation that annual average thunderstorm days are the maximum at the same volt- age level and altitude in the wodd. We detailedly described testing methods and steps of 6 characteristic parameters for grounding device of 750 kV substation by using 8000S comprehensive test system, and scientifically judged overall performance of the grounding device. Moreover, we espe- cially emphasized key and difficult points in testing process, providing reference for the majority of grounding test workers. 展开更多
关键词 750 kV substation Grounding device Characteristic parameters Testing research China
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The Characteristics of the Surface Topography of Excimer Laser Processed Al_2O_3 Ceramic
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作者 刘莹 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2004年第B10期11-14,共4页
Surface of Al 2O 3 ceramic was processed by an excimer laser and the characteristics of topography were examined based on the application of the microelectromechanical system(MEMS). It is indicated that the statisti... Surface of Al 2O 3 ceramic was processed by an excimer laser and the characteristics of topography were examined based on the application of the microelectromechanical system(MEMS). It is indicated that the statistic parameters of surface topography processed by the excimer laser have an obvious regularity. The arithmetic-mean value R a and the root-mean square value R q change with the changing of processing parameters in the same step and trend, and there is a quantitative relation between them.A simplified model is proposed for the excimer laser processing surface profile, whose results of the analysis and calculation agree basically with the experimental data. Furthermore,the surfaces processed by excimer laser are greatly flat. Skewness root-mean-square value Z· q changed little with the change of the technological parameters. The above characteristics depend on the processing principle of excimer laser, quite different from the cutting processing. 展开更多
关键词 excimer laser processing surface topography characteristics of topography parameters
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Research on Characteristic Parameters of Lightning Discharge Channels Based on Spectrum
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作者 Caixia DONG 《Meteorological and Environmental Research》 CAS 2021年第2期20-22,共3页
According to the time-resolved spectra of lightning return stroke process and based on the plasma transmission theory,the evolution characteristics of the thermal conductivity and thermal diffusion coefficient of the ... According to the time-resolved spectra of lightning return stroke process and based on the plasma transmission theory,the evolution characteristics of the thermal conductivity and thermal diffusion coefficient of the discharge channel over time during the lightning return stroke are discussed.The radial distribution of the channel temperature in the lightning peak current phase is calculated,and the heat transfer along the radial direction of the channel is analyzed.The calculated transmission characteristic parameter values of the lightning discharge channel are all in a reasonable range.The results show that the heat transport coefficient of the lightning channel is closely related to the channel temperature and electron density.After returning to the peak current,the channel temperature slowly decreases,and the transport coefficient shows a non-linear and monotonous decay trend.The closer to the current core channel is,the greater the temperature gradient is,and the more the heat transferred radially outward is. 展开更多
关键词 Lightning discharge channel Thermal conductivity Transport coefficient Characteristic parameter
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DBN-GABP model for estimation of aircraft wake vortex parameters using Lidar data 被引量:1
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作者 Zhiqiang WEI Tong LU +1 位作者 Runping GU Fei LIU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第9期347-368,共22页
Aircraft wake turbulence is an inherent outcome of aircraft flight,presenting a substan-tial challenge to air traffic control,aviation safety and operational efficiency.Building upon data obtained from coherent Dopple... Aircraft wake turbulence is an inherent outcome of aircraft flight,presenting a substan-tial challenge to air traffic control,aviation safety and operational efficiency.Building upon data obtained from coherent Doppler Lidar detection,and combining Dynamic Bayesian Networks(DBN)with Genetic Algorithm-optimized Backpropagation Neural Networks(GA-BPNN),this paper proposes a model for the inversion of wake vortex parameters.During the wake vortex flow field simulation analysis,the wind and turbulent environment were initially superimposed onto the simulated wake velocity field.Subsequently,Lidar-detected echoes of the velocity field are simulated to obtain a data set similar to the actual situation for model training.In the case study validation,real measured data underwent preprocessing and were then input into the established model.This allowed us to construct the wake vortex characteristic parameter inversion model.The final results demonstrated that our model achieved parameter inversion with only minor errors.In a practical example,our model in this paper significantly reduced the mean square error of the inverted velocity field when compared to the traditional algorithm.This study holds significant promise for real-time monitoring of wake vortices at airports,and is proved a crucial step in developing wake vortex interval standards. 展开更多
关键词 Air traffic control Wake vortex flow field simulation Lidar echo simulation DBNmodel GA-BP model Wakevortex characteristic parameter inversion model
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