The subbottom profiling is an important means of marine engineering survey, hazardous geology study and continental shelf scientific research. The accuracy of subbottom profile data interpretation has a direct impact ...The subbottom profiling is an important means of marine engineering survey, hazardous geology study and continental shelf scientific research. The accuracy of subbottom profile data interpretation has a direct impact on the research and investigation results. Because some of profilers’ transducer and hydrophone are separately installed, when the survey area is very shallow, distortion of shallow layers will be caused if it is seen as a self-excited and self-collected single-channel seismic system. According to the principle of subbottom profiler, the distortion correction formula is deduced and analyzed, providing actual value to using C-View software to interpret such subbottom profile data more accurately. In addition, the seabed sediments sound velocity is one of the key parameters when acquiring and processing the subbottom profile data. On the basis of comparing some sound velocity forecasting empirical equations, the LU Bo’s equation was considered the most appropriate to predict the seabed sediments, sound velocity at near-shore of China. In a survey of an artificial island site, the LU Bo’s equation and the porosity data obtained from geological drilling were utilized to predict the sediments sound velocity, and the sound velocity structure profile was plotted, which was applied in processing the subbottom profile data of the artificial island investigation. The method of using porosity data to predict sediments sound velocity in processing subbottom profile data can improve the interpretation accuracy and it’s of practical significance.展开更多
A new algorithm using orthogonal polynomials and sample moments was presented for estimating probability curves directly from experimental or field data of rock variables. The moments estimated directly from a sample ...A new algorithm using orthogonal polynomials and sample moments was presented for estimating probability curves directly from experimental or field data of rock variables. The moments estimated directly from a sample of observed values of a random variable could be conventional moments (moments about the origin or central moments) and probability-weighted moments (PWMs). Probability curves derived from orthogonal polynomials and conventional moments are probability density functions (PDF), and probability curves derived from orthogonal polynomials and PWMs are inverse cumulative density functions (CDF) of random variables. The proposed approach is verified by two most commonly-used theoretical standard distributions: normal and exponential distribution. Examples from observed data of uniaxial compressive strength of a rock and concrete strength data are presented for illustrative purposes. The results show that probability curves of rock variable can be accurately derived from orthogonal polynomials and sample moments. Orthogonal polynomials and PWMs enable more secure inferences to be made from relatively small samples about an underlying probability curve.展开更多
There is little low-and-high frequency information on seismic data in seismic exploration,resulting in narrower bandwidth and lower seismic resolution.It considerably restricts the prediction accuracy of thin reservoi...There is little low-and-high frequency information on seismic data in seismic exploration,resulting in narrower bandwidth and lower seismic resolution.It considerably restricts the prediction accuracy of thin reservoirs and thin interbeds.This study proposes a novel method to constrain improving seismic resolution in the time and frequency domain.The expected wavelet spectrum is used in the frequency domain to broaden the seismic spectrum range and increase the octave.In the time domain,the Frobenius vector regularization of the Hessian matrix is used to constrain the horizontal continuity of the seismic data.It eff ectively protects the signal-to-noise ratio of seismic data while the longitudinal seismic resolution is improved.This method is applied to actual post-stack seismic data and pre-stack gathers dividedly.Without abolishing the phase characteristics of the original seismic data,the time resolution is signifi cantly improved,and the structural features are clearer.Compared with the traditional spectral simulation and deconvolution methods,the frequency distribution is more reasonable,and seismic data has higher resolution.展开更多
For a conventional high-power active power factor correction(APFC)boost converter,its output capacitor needs to be precharged,which means that two power switches of the main circuit and the control circuit are needed ...For a conventional high-power active power factor correction(APFC)boost converter,its output capacitor needs to be precharged,which means that two power switches of the main circuit and the control circuit are needed to be respectively turned on and turned off in a fixed order.After the main circuit switch is turned on,it is necessary to wait for precharging before turning on the control circuit power switch.Once an inadvertent operation is performed,an overcurrent phenomenon from the output capacitor will occur.In this study,the buck circuit is used as the pre-stage snubber circuit,which can directly supply power to the circuit without precharging the output capacitor.As a result,potential safety hazard caused by the overcurrent due to the capacitor and the charging maloperation during the start-up stage can be avoided.Theoretical analysis and simulation experiment show that the DC boost converter with buck buffer can maintain the peak value of the main circuit within the safe range when the device boot does not precharge the output capacitor,and thus the safety and stable operation of the DC boost converter are ensured.展开更多
A precise zoom magnification is important for semiconductor industry and biomedical research. A novel measurement method is demonstrated for optical zoom magnification measurement in this paper. The magnification is o...A precise zoom magnification is important for semiconductor industry and biomedical research. A novel measurement method is demonstrated for optical zoom magnification measurement in this paper. The magnification is obtained by pattern correction between barcode image formed by optical zoom and reference image generated by an ideal optical model. Measurement accuracy which is better than 0.06% has been achieved for optical zoom magnification. Compared with traditional concept, the measurement results are only dependent on two line edges. The barcode correlation method can achieve higher accuracy and better robustness by using the information over the whole field of view.展开更多
A reliability based analysis method for a drilled shaft stabilized slope system is presented in this paper. The drilled shaft stabilization mechanisms for the slope were treated as the drilled shaft induced soil archi...A reliability based analysis method for a drilled shaft stabilized slope system is presented in this paper. The drilled shaft stabilization mechanisms for the slope were treated as the drilled shaft induced soil arching, which was quantified by the load transfer factor in the limited equilibrium analysis. However, due to the inherent uncertainties of the soil properties and the model error of the semi-empirical load transfer equation, an extension modification of the deterministic method into a probabilistic method is developed in this paper. The MCS (Monte Carlo simulation) with log-normal random variables has been employed to calculate the probability of failure (Pf) for the drilled shafts/slope system. The developed theories were coded into a computer program for analyzing complex slope geometry and slope profile conditions. Finally, a case study has been performed to illustrate the application analysis of the developed probability approach in drilled shafts/slope system.展开更多
A high accuracy experimental system has been established for unsteady open-channel flow.Then 40 experiments were conducted to study the propagating characteristics of unsteady open-channel flow.From the experimental d...A high accuracy experimental system has been established for unsteady open-channel flow.Then 40 experiments were conducted to study the propagating characteristics of unsteady open-channel flow.From the experimental data,the variation law of propagating velocity,wave deformation rate,flow depth of wave peak and bottom,and other parameters were obtained.The experimental results show the followings.1) The propagating velocity of unsteady open-channel flows can be expressed by the sum of flow velocity and micro-amplitude wave velocity at wave peak.2) The waveform of an unsteady flow would deform when it propagates,with the rising stage becoming longer and the falling stage shorter;the deformation rate is a function of distance,period and relative amplitude of discharge.3) The flow depths of wave peak and bottom have a close relationship with the period of the unsteady flow.When the period is short,water depths of wave peak and bottom are both close to those of the average discharge in the condition of uniform flow.For a long period unsteady flow,the water depth of wave peak is close to that of the maximal discharge in the condition of uniform flow,while at the flow wave bottom,it is close to the depth of the minimum discharge in an uniform flow.4) Propagating characteristic of discharge is analogous to that of flow depth for unsteady flow.展开更多
This paper focuses on the variability in entrainment rate in individual cumulus clouds using the entrainment rate estimated on the scale of 5 m in 186 shallow cumulus clouds from eight aircraft flights, using in situ ...This paper focuses on the variability in entrainment rate in individual cumulus clouds using the entrainment rate estimated on the scale of 5 m in 186 shallow cumulus clouds from eight aircraft flights, using in situ observations from the RACORO field campaign (the routine atmospheric radiation measurement aerial facility clouds with low optical water depths optical radiative observations) over the atmospheric radiation measurement Southern Great Plains site, USA. The result shows that the mean entrainment rate of all the 186 clouds systematically decreases from the cloud edge to the cloud center. Further analysis of the fluctuation of entrainment rate shows that the probability density function of entrainment rate in each flight can be fitted by the lognormal, gamma, or Weibull distributions virtually equally well, with the Weibull dis- tribution being the best. The parameter "standard devia- tion" in the lognormal distribution is weakly negatively correlated, and the other parameters in the three distribu- tions are positively correlated with relative humidity in the entrained dry air and dilution effect, respectively. Entrainment rate is negatively correlated with droplet concentration, droplet size, and liquid water content, but positively correlated with relative dispersion. The effect of entrainment rate on the spectral shape of cloud droplet size distribution is examined and linked to the systems theory on the cloud droplet size distribution.展开更多
The author obtains the theorems of Barth-Lefschetz type on Kahler manifolds with partiallypositive bisectional curvature without the assumption of nonnegative bisectional curvature.Some applications of the results to ...The author obtains the theorems of Barth-Lefschetz type on Kahler manifolds with partiallypositive bisectional curvature without the assumption of nonnegative bisectional curvature.Some applications of the results to holomorphic mappings are given.展开更多
文摘The subbottom profiling is an important means of marine engineering survey, hazardous geology study and continental shelf scientific research. The accuracy of subbottom profile data interpretation has a direct impact on the research and investigation results. Because some of profilers’ transducer and hydrophone are separately installed, when the survey area is very shallow, distortion of shallow layers will be caused if it is seen as a self-excited and self-collected single-channel seismic system. According to the principle of subbottom profiler, the distortion correction formula is deduced and analyzed, providing actual value to using C-View software to interpret such subbottom profile data more accurately. In addition, the seabed sediments sound velocity is one of the key parameters when acquiring and processing the subbottom profile data. On the basis of comparing some sound velocity forecasting empirical equations, the LU Bo’s equation was considered the most appropriate to predict the seabed sediments, sound velocity at near-shore of China. In a survey of an artificial island site, the LU Bo’s equation and the porosity data obtained from geological drilling were utilized to predict the sediments sound velocity, and the sound velocity structure profile was plotted, which was applied in processing the subbottom profile data of the artificial island investigation. The method of using porosity data to predict sediments sound velocity in processing subbottom profile data can improve the interpretation accuracy and it’s of practical significance.
文摘A new algorithm using orthogonal polynomials and sample moments was presented for estimating probability curves directly from experimental or field data of rock variables. The moments estimated directly from a sample of observed values of a random variable could be conventional moments (moments about the origin or central moments) and probability-weighted moments (PWMs). Probability curves derived from orthogonal polynomials and conventional moments are probability density functions (PDF), and probability curves derived from orthogonal polynomials and PWMs are inverse cumulative density functions (CDF) of random variables. The proposed approach is verified by two most commonly-used theoretical standard distributions: normal and exponential distribution. Examples from observed data of uniaxial compressive strength of a rock and concrete strength data are presented for illustrative purposes. The results show that probability curves of rock variable can be accurately derived from orthogonal polynomials and sample moments. Orthogonal polynomials and PWMs enable more secure inferences to be made from relatively small samples about an underlying probability curve.
基金supported by the PetroChina Prospective,Basic,and Strategic Technology Research Project(No.2021DJ0606).
文摘There is little low-and-high frequency information on seismic data in seismic exploration,resulting in narrower bandwidth and lower seismic resolution.It considerably restricts the prediction accuracy of thin reservoirs and thin interbeds.This study proposes a novel method to constrain improving seismic resolution in the time and frequency domain.The expected wavelet spectrum is used in the frequency domain to broaden the seismic spectrum range and increase the octave.In the time domain,the Frobenius vector regularization of the Hessian matrix is used to constrain the horizontal continuity of the seismic data.It eff ectively protects the signal-to-noise ratio of seismic data while the longitudinal seismic resolution is improved.This method is applied to actual post-stack seismic data and pre-stack gathers dividedly.Without abolishing the phase characteristics of the original seismic data,the time resolution is signifi cantly improved,and the structural features are clearer.Compared with the traditional spectral simulation and deconvolution methods,the frequency distribution is more reasonable,and seismic data has higher resolution.
基金National Natural Science Foundation of China(No.61761027)。
文摘For a conventional high-power active power factor correction(APFC)boost converter,its output capacitor needs to be precharged,which means that two power switches of the main circuit and the control circuit are needed to be respectively turned on and turned off in a fixed order.After the main circuit switch is turned on,it is necessary to wait for precharging before turning on the control circuit power switch.Once an inadvertent operation is performed,an overcurrent phenomenon from the output capacitor will occur.In this study,the buck circuit is used as the pre-stage snubber circuit,which can directly supply power to the circuit without precharging the output capacitor.As a result,potential safety hazard caused by the overcurrent due to the capacitor and the charging maloperation during the start-up stage can be avoided.Theoretical analysis and simulation experiment show that the DC boost converter with buck buffer can maintain the peak value of the main circuit within the safe range when the device boot does not precharge the output capacitor,and thus the safety and stable operation of the DC boost converter are ensured.
文摘A precise zoom magnification is important for semiconductor industry and biomedical research. A novel measurement method is demonstrated for optical zoom magnification measurement in this paper. The magnification is obtained by pattern correction between barcode image formed by optical zoom and reference image generated by an ideal optical model. Measurement accuracy which is better than 0.06% has been achieved for optical zoom magnification. Compared with traditional concept, the measurement results are only dependent on two line edges. The barcode correlation method can achieve higher accuracy and better robustness by using the information over the whole field of view.
文摘A reliability based analysis method for a drilled shaft stabilized slope system is presented in this paper. The drilled shaft stabilization mechanisms for the slope were treated as the drilled shaft induced soil arching, which was quantified by the load transfer factor in the limited equilibrium analysis. However, due to the inherent uncertainties of the soil properties and the model error of the semi-empirical load transfer equation, an extension modification of the deterministic method into a probabilistic method is developed in this paper. The MCS (Monte Carlo simulation) with log-normal random variables has been employed to calculate the probability of failure (Pf) for the drilled shafts/slope system. The developed theories were coded into a computer program for analyzing complex slope geometry and slope profile conditions. Finally, a case study has been performed to illustrate the application analysis of the developed probability approach in drilled shafts/slope system.
基金supported by the National Key Technology R & D Programof China (Grant No. 2011BAB09B01)the Chongqing Natural Science Foundation of China (Grant No. cstc2011jjA1167)
文摘A high accuracy experimental system has been established for unsteady open-channel flow.Then 40 experiments were conducted to study the propagating characteristics of unsteady open-channel flow.From the experimental data,the variation law of propagating velocity,wave deformation rate,flow depth of wave peak and bottom,and other parameters were obtained.The experimental results show the followings.1) The propagating velocity of unsteady open-channel flows can be expressed by the sum of flow velocity and micro-amplitude wave velocity at wave peak.2) The waveform of an unsteady flow would deform when it propagates,with the rising stage becoming longer and the falling stage shorter;the deformation rate is a function of distance,period and relative amplitude of discharge.3) The flow depths of wave peak and bottom have a close relationship with the period of the unsteady flow.When the period is short,water depths of wave peak and bottom are both close to those of the average discharge in the condition of uniform flow.For a long period unsteady flow,the water depth of wave peak is close to that of the maximal discharge in the condition of uniform flow,while at the flow wave bottom,it is close to the depth of the minimum discharge in an uniform flow.4) Propagating characteristic of discharge is analogous to that of flow depth for unsteady flow.
基金supported by the National Natural Science Foundation of China(41305120,91337215)the Research Foundation for Environmental Protection of Jiangsu Province(2013042)+9 种基金the Natural Science Foundation of Jiangsu Province,China(BK20130988)the Specialized Research Foundation for the Doctoral Program of Higher Education(20133228120002)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province,China(13KJB170014)China Meteorological Administration Special Public Welfare Research Foundation(GYHY201406007)the Open Funding from State Key Laboratory of Severe Weather(2013LASW-B06)the Open Funding from Key Laboratory of Meteorological Disaster of Ministry of Education,China(KLME1305)the Qing Lan Projecta Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe US Department of Energy’s(DOE)Earth System Modeling(ESM)program via the FASTER project(www.bnl.gov/faster)Atmospheric System Research(ASR)Program
文摘This paper focuses on the variability in entrainment rate in individual cumulus clouds using the entrainment rate estimated on the scale of 5 m in 186 shallow cumulus clouds from eight aircraft flights, using in situ observations from the RACORO field campaign (the routine atmospheric radiation measurement aerial facility clouds with low optical water depths optical radiative observations) over the atmospheric radiation measurement Southern Great Plains site, USA. The result shows that the mean entrainment rate of all the 186 clouds systematically decreases from the cloud edge to the cloud center. Further analysis of the fluctuation of entrainment rate shows that the probability density function of entrainment rate in each flight can be fitted by the lognormal, gamma, or Weibull distributions virtually equally well, with the Weibull dis- tribution being the best. The parameter "standard devia- tion" in the lognormal distribution is weakly negatively correlated, and the other parameters in the three distribu- tions are positively correlated with relative humidity in the entrained dry air and dilution effect, respectively. Entrainment rate is negatively correlated with droplet concentration, droplet size, and liquid water content, but positively correlated with relative dispersion. The effect of entrainment rate on the spectral shape of cloud droplet size distribution is examined and linked to the systems theory on the cloud droplet size distribution.
文摘The author obtains the theorems of Barth-Lefschetz type on Kahler manifolds with partiallypositive bisectional curvature without the assumption of nonnegative bisectional curvature.Some applications of the results to holomorphic mappings are given.