A clock bias data processing method based on interval correlation coefficient wavelet threshold denoising is suggested for minor mistakes in clock bias data in order to increase the efficacy of satellite clock bias pr...A clock bias data processing method based on interval correlation coefficient wavelet threshold denoising is suggested for minor mistakes in clock bias data in order to increase the efficacy of satellite clock bias prediction.Wavelet analysis was first used to break down the satellite clock frequency data into several levels,producing high and low frequency coefficients for each layer.The correlation coefficients of the high and low frequency coefficients in each of the three sub-intervals created by splitting these coefficients were then determined.The major noise region—the sub-interval with the lowest correlation coefficient—was chosen for thresholding treatment and noise threshold computation.The clock frequency data was then processed using wavelet reconstruction and reconverted to clock data.Lastly,three different kinds of satellite clock data—RTS,whu-o,and IGS-F—were used to confirm the produced data.Our method enhanced the stability of the Quadratic Polynomial(QP)model’s predictions for the C16 satellite by about 40%,according to the results.The accuracy and stability of the Auto Regression Integrated Moving Average(ARIMA)model improved up to 41.8%and 14.2%,respectively,whilst the Wavelet Neural Network(WNN)model improved by roughly 27.8%and 63.6%,respectively.Although our method has little effect on forecasting IGS-F series satellites,the experimental findings show that it can improve the accuracy and stability of QP,ARIMA,and WNN model forecasts for RTS and whu-o satellite clock bias.展开更多
We analyzed the infrared 0R）-near infrared （NIR） 2D correlation spectra of drugs perturbed by temperature. By identification of functional groups by IR spectrum and by the correlation analysis of IR-NIR spectrum, w...We analyzed the infrared 0R）-near infrared （NIR） 2D correlation spectra of drugs perturbed by temperature. By identification of functional groups by IR spectrum and by the correlation analysis of IR-NIR spectrum, we identified the characteristic spectral bands that were closely related to the structure of a drug substance of interest. These characteristic spectral bands were relatively less interfered by other ingredients for analysis by the NIR correlation coefficient method. With these characteristic spectral bands, the accuracy of screening illegally added Sildenafil citrate, Tadalafil and Metforrnin hydrochloride in Chinese patent drugs and healthcare products reached about 90%, which met the requirements of rapid screening.展开更多
The correlation coefficients of random variables of mechanical structures are generally chosen with experience or even ignored,which cannot actually reflect the effects of parameter uncertainties on reliability.To dis...The correlation coefficients of random variables of mechanical structures are generally chosen with experience or even ignored,which cannot actually reflect the effects of parameter uncertainties on reliability.To discuss the selection problem of the correlation coefficients from the reliability-based sensitivity point of view,the theory principle of the problem is established based on the results of the reliability sensitivity,and the criterion of correlation among random variables is shown.The values of the correlation coefficients are obtained according to the proposed principle and the reliability sensitivity problem is discussed.Numerical studies have shown the following results：（1） If the sensitivity value of correlation coefficient ρ is less than（at what magnitude 0.000 01）,then the correlation could be ignored,which could simplify the procedure without introducing additional error.（2） However,as the difference between ρs,that is the most sensitive to the reliability,and ρR,that is with the smallest reliability,is less than 0.001,ρs is suggested to model the dependency of random variables.This could ensure the robust quality of system without the loss of safety requirement.（3） In the case of ｜Eabs｜ρ0.001 and also ｜Erel｜ρ0.001,ρR should be employed to quantify the correlation among random variables in order to ensure the accuracy of reliability analysis.Application of the proposed approach could provide a practical routine for mechanical design and manufactory to study the reliability and reliability-based sensitivity of basic design variables in mechanical reliability analysis and design.展开更多
In microwave tomography, it is necessary to increase the amount of diverse observation data for accurate image reconstruction of the dielectric properties of the imaging area. The multi-polarization method has been pr...In microwave tomography, it is necessary to increase the amount of diverse observation data for accurate image reconstruction of the dielectric properties of the imaging area. The multi-polarization method has been proposed as a suitable technique for the acquisition of a variety of observation data. While the effectiveness of employing multi-polarization to reconstruct images has been confirmed, the physical considerations related to image reconstruction have not been investigated. In this paper, a compact-sized imaging sensor using multi-polarization for breast cancer detection is presented. An analysis of the correlation coefficient of the received data of adjacent antennas was performed to interpret the imaging results. Numerical simulation results demonstrated that multi-polarization can reconstruct images better compared to single polarizations owing to its low correlation coefficient and condition number.展开更多
Four rapid spectral comparison methods are introduced in mobile labs.They are conformity test method,general correlation coefficient method,reverse correlation coefficient method and correlation coefficient method usi...Four rapid spectral comparison methods are introduced in mobile labs.They are conformity test method,general correlation coefficient method,reverse correlation coefficient method and correlation coefficient method using characteristic spectral ranges.The first method is used for tracking the movements of drugs in the distribution channels;the second is used for quickly identify new counterfeit drugs;the last two are used to screen drugs illegally added in Traditional Chinese Medicine （TCM）.The applicability of the four methods is evaluated with counterfeit and authentic drugs.Our results show that these methods can be quickly constructed and used to identify counterfeit drugs accurately.展开更多
In the case of unknown weights, theories of multi-attributed decision making based on interval numbers and grey related analysis were used to optimize mining methods. As the representative of independence for the indi...In the case of unknown weights, theories of multi-attributed decision making based on interval numbers and grey related analysis were used to optimize mining methods. As the representative of independence for the indicator, the smaller the correlation of indicators is, the greater the weight is. Hence, the weights of interval numbers of indicators were determined by using correlation coefficient. Relative closeness based on positive and negative ideal methods was calculated by introducing distance between interval numbers, which made decision making more rational and comprehensive. A new method of ranking interval numbers based on normal distribution was proposed for the optimization of mining methods, whose basic properties were discussed. Finally, the feasibility and effectiveness of this method were verified by theories and practice.展开更多
The double-threshold method has been widely used in ultrasonic flow measurement to determine time-of-flight(TOF)due to its low cost and ease of implementation.Performance of this method is negatively affected by the c...The double-threshold method has been widely used in ultrasonic flow measurement to determine time-of-flight(TOF)due to its low cost and ease of implementation.Performance of this method is negatively affected by the cycle-skip phenomenon which occurs frequently under inconstant working conditions,especially varied fluid temperature.This paper proposes a method to suppress the phenomenon to facilitate reliable determination of TOF in ultrasonic flow measurement.First,the double-threshold method is used to generate a feature point to segment the signal.Second,based on the correlation coefficient and signal power,judgement factors of individual signal periods are calculated to determine signal onset.Finally,a valid zero crossing which has a constant lag from the onset is selected to determine the TOF.Thus,the cycle-skip phenomenon is suppressed.Two additional modifications are proposed to eliminate the influence of varied signal frequency and low sampling rate.The proposed method was validated by an experiment based on an ultrasonic water flow sensor.Results showed that the frequently appearing cycle-skip phenomenon can be successfully suppressed by the proposed method.展开更多
Particle size fraction(clay, silt, and sand) is an important characteristic that influences several soil functions. The laser-diffraction method(LDM) provides a fast and cost-effective measurement of particle size dis...Particle size fraction(clay, silt, and sand) is an important characteristic that influences several soil functions. The laser-diffraction method(LDM) provides a fast and cost-effective measurement of particle size distribution, but the results usually differ from those obtained by the traditional sieve-pipette method(SPM). This difference can persist even when calibration is applied between the two methods. This partly relates to the different size ranges of particles measured by the two methods as a result of different operational principles, i.e., particle sedimentation according to Stokes’ Law vs. Mie theory for laser beam scattering. The objective of this study was to identify particle size ranges of LDM equivalent to those measured by SPM and evaluate whether new calibration models based on size range correction can be used to improve LDM-estimated particle size fractions, using 51 soil samples with various texture collected from five soil orders in New Zealand. Particle size distribution was determined using both LDM and SPM. Compared with SPM, original data from LDM underestimated the clay fraction(< 2 μm), overestimated the silt fraction(2–53 μm), but provided a good estimation of the sand fraction(53–2 000 μm).Results from three statistical indices, including Pearson’s correlation coefficient, slope, and Lin’s concordance correlation coefficient, showed that the size ranges of < 2 and 2–53 μm defined by SPM corresponded with the < 5 and 5–53 μm size ranges by LDM, respectively. Compared with the traditional calibration(based on the same particle size ranges), new calibration models(based on the corrected size ranges of these two methods) improved the estimation of clay and silt contents by LDM. Compared with soil-specific models(i.e., different models were developed for different soils), a universal model may be more parsimonious for estimating particle size fractions if the samples to be assessed represent multiple soil orders.展开更多
Systemreliability sensitivity analysis becomes difficult due to involving the issues of the correlation between failure modes whether using analytic method or numerical simulation methods.A fast conditional reduction ...Systemreliability sensitivity analysis becomes difficult due to involving the issues of the correlation between failure modes whether using analytic method or numerical simulation methods.A fast conditional reduction method based on conditional probability theory is proposed to solve the sensitivity analysis based on the approximate analytic method.The relevant concepts are introduced to characterize the correlation between failure modes by the reliability index and correlation coefficient,and conditional normal fractile the for the multi-dimensional conditional failure analysis is proposed based on the two-dimensional normal distribution function.Thus the calculation of system failure probability can be represented as a summation of conditional probability terms,which is convenient to be computed by iterative solving sequentially.Further the system sensitivity solution is transformed into the derivation process of the failure probability correlation coefficient of each failure mode.Numerical examples results show that it is feasible to apply the idea of failure mode relevancy to failure probability sensitivity analysis,and it can avoid multi-dimension integral calculation and reduce complexity and difficulty.Compared with the product of conditional marginalmethod,a wider value range of correlation coefficient for reliability analysis is confirmed and an acceptable accuracy can be obtained with less computational cost.展开更多
OBJECTIVE:To optimize the vinegar-steaming process of Wuweizi(Fructus Schisandrae Chinensis)using the response surface method(RSM)based on the Box-Behnken design.METHODS:A regression model was constructed with the res...OBJECTIVE:To optimize the vinegar-steaming process of Wuweizi(Fructus Schisandrae Chinensis)using the response surface method(RSM)based on the Box-Behnken design.METHODS:A regression model was constructed with the response variables,the content of Deoxyschizandrin,and the three explanatory factors:length of steaming time,the quantity of vinegar and length of moistening time to evaluate the effects on the processing of Wuweizi(Fructus SchisandraeChinensis).RESULTS:There was a linear relationship between the content of Deoxyschizandrin and the three explanatory factors.When the steaming time was5.49 h,with 2.365 g of vinegar added and a moistening time of 4.13 h,the content of Deoxyschizandrin reached the maximum predicted value of0.1076%,and under the conditions the average content of Deoxyschizandrin was 0.1058%.CONCLUSION:The correlation coefficient of thenonlinear mathematical model was relatively high and the model matched the data well,potentially providing a method for the study of the steaming process.展开更多
According to the relationship between load and response, the equivalent static wind load(ESWL) of a structure can be estimated by load-response correlation(LRC) method, which can be accurately used to estimate the bac...According to the relationship between load and response, the equivalent static wind load(ESWL) of a structure can be estimated by load-response correlation(LRC) method, which can be accurately used to estimate the background ESWL of a structure. The derivation of the classical expression of LRC formula is based on a specific command response at a critical position, and the ESWL distribution has only one form in this case. In this paper, a general expression of LRC formula is derived based on a specific command response at all positions. For the general expression, ESWLs can be expressed by load-response correlation coefficients, response-response correlation coefficients, RMS values of the fluctuating wind loads, and peak factor in the form of matrices. By comparing the expressions of LRC method, it was found that the classical expression was only one form of the general one. The general expression which introduces the response-response correlation coefficients provided more options for structural engineers to estimate ESWLs and offered further insights into the LRC method. Finally, a cable-stayed bridge, a rigid three span continuous girder bridge, and a suspension bridge were used to verify the correctness of the general expression of LRC method.展开更多
The complex resistivity of coal and related rocks contains abundant physical property information,which can be indirectly used to study the lithology and microstructure of these materials.These aspects are closely rel...The complex resistivity of coal and related rocks contains abundant physical property information,which can be indirectly used to study the lithology and microstructure of these materials.These aspects are closely related to the fluids inside the considered coal rocks,such as gas,water and coalbed methane.In the present analysis,considering different lithological structures,and using the Cole-Cole model,a forward simulation method is used to study different physical parameters such as the zero-frequency resistivity,the polarizability,the relaxation time,and the frequency correlation coefficient.Moreover,using a least square technique,a complex resistivity“inversion”algorithm is written.The comparison of the initial model parameters and those obtained after inversion is used to verify the stability and accuracy of such approach.The method is finally applied to primary-structure coal considered as the experimental sample for complex resistivity measurements.展开更多
Applied statisticians are often confronted with statistical inference problems dealing with situations in which there appear to be no data,or data of only limited usefulness.For example,when attempting to find a confi...Applied statisticians are often confronted with statistical inference problems dealing with situations in which there appear to be no data,or data of only limited usefulness.For example,when attempting to find a confidence interval for a binomial proportion,the sample may contain no successes.Such a scenario could be encountered when attempting to estimate the incidence of an extremely rare side effect associated with the administration of a newly developed drug.In this article,we use examples for our experiences working with scientific investigators and describe several scenarios in which there appeared to be no useful data,or data of only limited usefulness.We describe the methods we prefer for analyzing the data in these situations and illustrate their application using the actual data from the investigations we participated in.展开更多
This article aimed to find a new way to transform the graphic image (drawing, photos, etc) to the pattern parameters of female apparel with raglan sleeve. The correlation and regressive analysis were used to the data ...This article aimed to find a new way to transform the graphic image (drawing, photos, etc) to the pattern parameters of female apparel with raglan sleeve. The correlation and regressive analysis were used to the data in order to find the existing laws between them. The practical examinations demonstrated the good predictability of equations established.展开更多
暴雨洪水管理模型(storm water management model,SWMM)的不确定参数在一定程度上影响着内涝模拟的精度,因此以中山市某研究区域为例,计算SWMM模型参数的初始值,采用最大互信息系数和偏相关系数探究短历时、长历时不同重现期下对径流总...暴雨洪水管理模型(storm water management model,SWMM)的不确定参数在一定程度上影响着内涝模拟的精度,因此以中山市某研究区域为例,计算SWMM模型参数的初始值,采用最大互信息系数和偏相关系数探究短历时、长历时不同重现期下对径流总量、出流总量、峰值流量和峰现时间敏感的参数,并利用熵权法确定2种方法的权重进行综合评价,结合综合分析得到的敏感参数和偏相关分析得到的变量之间的正负相关关系,选取8场历史降雨对模型进行率定与验证。结果表明:2种方法得到的各重现期下敏感参数并不完全一致;综合分析发现不同重现期要考虑的敏感参数略有不同,且各重现期最敏感参数与最大互信息系数的结果一致;P=10 a、20 a同一重现期不同降雨历时下敏感参数存在较大差异;模型模拟的管网井下液位的纳什效率系数均大于0.7,峰现时间误差均小于等于30 min,峰值相对误差的绝对值均小于3.5%。通过深入分析模型参数的不确定性,可提高参数率定效率和模型的准确度。展开更多
为快速、准确预测接触网复合绝缘子临界污闪电压,减少人工污秽试验工作量,提出了一种复合绝缘子污秽闪络电压预测模型。首先,利用黄金正弦(golden sine algorithm,GSA)与分段线性混沌映射(piecewise linear chaotic map,PWLCM)改进的减...为快速、准确预测接触网复合绝缘子临界污闪电压,减少人工污秽试验工作量,提出了一种复合绝缘子污秽闪络电压预测模型。首先,利用黄金正弦(golden sine algorithm,GSA)与分段线性混沌映射(piecewise linear chaotic map,PWLCM)改进的减法平均优化器(subtraction average based optimizer,SABO)算法增强反向传播(back propagation,BP)神经网络的性能;其次,利用人工污秽试验获取10种不同复合绝缘子的闪络电压,收集相关试验参数;再次,依据Obenaus模型对复合绝缘子污秽闪络表现进行分析,利用斯皮尔曼(Spearman)相关系数法筛选出与复合绝缘子临界污闪电压密切相关的4个参数作为预测模型的输入特征量,以预测复合绝缘子临界污闪电压;最后,利用五折交叉验证法对预测模型进行综合评估,并与常用智能优化算法预测模型的预测结果进行比较。结果表明:GSABO-BP模型预测复合绝缘子污闪电压平均绝对误差为1.244 kV,平均绝对百分比误差为2.25%,模型可决系数稳定在0.98以上;与改进前的SABO-BP模型相比,预测值平均误差下降67.80%。GSABO-BP模型在复合绝缘子污闪电压预测上具有较高的预测精准度,对电气化铁路供电系统的防污保护工作具有重要意义。展开更多
基金2023 Liaoning Institute of Science and Technology Doctoral Program Launch fund(No.2307B29).
文摘A clock bias data processing method based on interval correlation coefficient wavelet threshold denoising is suggested for minor mistakes in clock bias data in order to increase the efficacy of satellite clock bias prediction.Wavelet analysis was first used to break down the satellite clock frequency data into several levels,producing high and low frequency coefficients for each layer.The correlation coefficients of the high and low frequency coefficients in each of the three sub-intervals created by splitting these coefficients were then determined.The major noise region—the sub-interval with the lowest correlation coefficient—was chosen for thresholding treatment and noise threshold computation.The clock frequency data was then processed using wavelet reconstruction and reconverted to clock data.Lastly,three different kinds of satellite clock data—RTS,whu-o,and IGS-F—were used to confirm the produced data.Our method enhanced the stability of the Quadratic Polynomial(QP)model’s predictions for the C16 satellite by about 40%,according to the results.The accuracy and stability of the Auto Regression Integrated Moving Average(ARIMA)model improved up to 41.8%and 14.2%,respectively,whilst the Wavelet Neural Network(WNN)model improved by roughly 27.8%and 63.6%,respectively.Although our method has little effect on forecasting IGS-F series satellites,the experimental findings show that it can improve the accuracy and stability of QP,ARIMA,and WNN model forecasts for RTS and whu-o satellite clock bias.
基金National Key Technology R & D Program-On-site Rapid Identification of Drug Research Project (Grant No. 2008BAI55B06)
文摘We analyzed the infrared 0R）-near infrared （NIR） 2D correlation spectra of drugs perturbed by temperature. By identification of functional groups by IR spectrum and by the correlation analysis of IR-NIR spectrum, we identified the characteristic spectral bands that were closely related to the structure of a drug substance of interest. These characteristic spectral bands were relatively less interfered by other ingredients for analysis by the NIR correlation coefficient method. With these characteristic spectral bands, the accuracy of screening illegally added Sildenafil citrate, Tadalafil and Metforrnin hydrochloride in Chinese patent drugs and healthcare products reached about 90%, which met the requirements of rapid screening.
基金supported by Changjiang Scholars and Innovative Research Team in University of China (Grant No. IRT0816)Key National Science & Technology Special Project on "High-Grade CNC Machine Tools and Basic Manufacturing Equipments" of China (Grant No. 2010ZX04014-014)+1 种基金National Natural Science Foundation of China (Grant No. 50875039)Key Projects in National Science & Technology Pillar Program during the 11th Five-year Plan Period of China (Grant No. 2009BAG12A02-A07-2)
文摘The correlation coefficients of random variables of mechanical structures are generally chosen with experience or even ignored,which cannot actually reflect the effects of parameter uncertainties on reliability.To discuss the selection problem of the correlation coefficients from the reliability-based sensitivity point of view,the theory principle of the problem is established based on the results of the reliability sensitivity,and the criterion of correlation among random variables is shown.The values of the correlation coefficients are obtained according to the proposed principle and the reliability sensitivity problem is discussed.Numerical studies have shown the following results：（1） If the sensitivity value of correlation coefficient ρ is less than（at what magnitude 0.000 01）,then the correlation could be ignored,which could simplify the procedure without introducing additional error.（2） However,as the difference between ρs,that is the most sensitive to the reliability,and ρR,that is with the smallest reliability,is less than 0.001,ρs is suggested to model the dependency of random variables.This could ensure the robust quality of system without the loss of safety requirement.（3） In the case of ｜Eabs｜ρ0.001 and also ｜Erel｜ρ0.001,ρR should be employed to quantify the correlation among random variables in order to ensure the accuracy of reliability analysis.Application of the proposed approach could provide a practical routine for mechanical design and manufactory to study the reliability and reliability-based sensitivity of basic design variables in mechanical reliability analysis and design.
文摘In microwave tomography, it is necessary to increase the amount of diverse observation data for accurate image reconstruction of the dielectric properties of the imaging area. The multi-polarization method has been proposed as a suitable technique for the acquisition of a variety of observation data. While the effectiveness of employing multi-polarization to reconstruct images has been confirmed, the physical considerations related to image reconstruction have not been investigated. In this paper, a compact-sized imaging sensor using multi-polarization for breast cancer detection is presented. An analysis of the correlation coefficient of the received data of adjacent antennas was performed to interpret the imaging results. Numerical simulation results demonstrated that multi-polarization can reconstruct images better compared to single polarizations owing to its low correlation coefficient and condition number.
基金National Key Technologies R&D Program Foundation of China(Grant No.2008BAI55B06).
文摘Four rapid spectral comparison methods are introduced in mobile labs.They are conformity test method,general correlation coefficient method,reverse correlation coefficient method and correlation coefficient method using characteristic spectral ranges.The first method is used for tracking the movements of drugs in the distribution channels;the second is used for quickly identify new counterfeit drugs;the last two are used to screen drugs illegally added in Traditional Chinese Medicine （TCM）.The applicability of the four methods is evaluated with counterfeit and authentic drugs.Our results show that these methods can be quickly constructed and used to identify counterfeit drugs accurately.
基金Project(50774095) supported by the National Natural Science Foundation of ChinaProject(200449) supported by the National Outstanding Doctoral Dissertations Special Funds of China
文摘In the case of unknown weights, theories of multi-attributed decision making based on interval numbers and grey related analysis were used to optimize mining methods. As the representative of independence for the indicator, the smaller the correlation of indicators is, the greater the weight is. Hence, the weights of interval numbers of indicators were determined by using correlation coefficient. Relative closeness based on positive and negative ideal methods was calculated by introducing distance between interval numbers, which made decision making more rational and comprehensive. A new method of ranking interval numbers based on normal distribution was proposed for the optimization of mining methods, whose basic properties were discussed. Finally, the feasibility and effectiveness of this method were verified by theories and practice.
基金Project supported by the Science Fund for Creative Research Groups of National Natural Science Foundation of China(No.51821093)。
文摘The double-threshold method has been widely used in ultrasonic flow measurement to determine time-of-flight(TOF)due to its low cost and ease of implementation.Performance of this method is negatively affected by the cycle-skip phenomenon which occurs frequently under inconstant working conditions,especially varied fluid temperature.This paper proposes a method to suppress the phenomenon to facilitate reliable determination of TOF in ultrasonic flow measurement.First,the double-threshold method is used to generate a feature point to segment the signal.Second,based on the correlation coefficient and signal power,judgement factors of individual signal periods are calculated to determine signal onset.Finally,a valid zero crossing which has a constant lag from the onset is selected to determine the TOF.Thus,the cycle-skip phenomenon is suppressed.Two additional modifications are proposed to eliminate the influence of varied signal frequency and low sampling rate.The proposed method was validated by an experiment based on an ultrasonic water flow sensor.Results showed that the frequently appearing cycle-skip phenomenon can be successfully suppressed by the proposed method.
基金completed as part of the Manaaki Whenua–Landcare Research-led MBIE Program,Soil Health and Resilience—A Pathway to Prosperity and Wellbeing(No.P/442062/01)Next Generation S-Map—Smarter Decisions(No.P/443063/01)+1 种基金the Plant&Food Research-led Strategic Science Investment Fund Program,Sustainable Agro-Ecosystemsfunded by the New Zealand Ministry of Business,Innovation and Employment。
文摘Particle size fraction(clay, silt, and sand) is an important characteristic that influences several soil functions. The laser-diffraction method(LDM) provides a fast and cost-effective measurement of particle size distribution, but the results usually differ from those obtained by the traditional sieve-pipette method(SPM). This difference can persist even when calibration is applied between the two methods. This partly relates to the different size ranges of particles measured by the two methods as a result of different operational principles, i.e., particle sedimentation according to Stokes’ Law vs. Mie theory for laser beam scattering. The objective of this study was to identify particle size ranges of LDM equivalent to those measured by SPM and evaluate whether new calibration models based on size range correction can be used to improve LDM-estimated particle size fractions, using 51 soil samples with various texture collected from five soil orders in New Zealand. Particle size distribution was determined using both LDM and SPM. Compared with SPM, original data from LDM underestimated the clay fraction(< 2 μm), overestimated the silt fraction(2–53 μm), but provided a good estimation of the sand fraction(53–2 000 μm).Results from three statistical indices, including Pearson’s correlation coefficient, slope, and Lin’s concordance correlation coefficient, showed that the size ranges of < 2 and 2–53 μm defined by SPM corresponded with the < 5 and 5–53 μm size ranges by LDM, respectively. Compared with the traditional calibration(based on the same particle size ranges), new calibration models(based on the corrected size ranges of these two methods) improved the estimation of clay and silt contents by LDM. Compared with soil-specific models(i.e., different models were developed for different soils), a universal model may be more parsimonious for estimating particle size fractions if the samples to be assessed represent multiple soil orders.
基金This research is supported by National Key Research and Development Project(Grant Number 2019YFD0901002)Also Natural Science Foundation of Liaoning Province(Grant Number 20170540105)Liaoning Province Education Foundation(Grant Number JL201913)are gratefully acknowledged.
文摘Systemreliability sensitivity analysis becomes difficult due to involving the issues of the correlation between failure modes whether using analytic method or numerical simulation methods.A fast conditional reduction method based on conditional probability theory is proposed to solve the sensitivity analysis based on the approximate analytic method.The relevant concepts are introduced to characterize the correlation between failure modes by the reliability index and correlation coefficient,and conditional normal fractile the for the multi-dimensional conditional failure analysis is proposed based on the two-dimensional normal distribution function.Thus the calculation of system failure probability can be represented as a summation of conditional probability terms,which is convenient to be computed by iterative solving sequentially.Further the system sensitivity solution is transformed into the derivation process of the failure probability correlation coefficient of each failure mode.Numerical examples results show that it is feasible to apply the idea of failure mode relevancy to failure probability sensitivity analysis,and it can avoid multi-dimension integral calculation and reduce complexity and difficulty.Compared with the product of conditional marginalmethod,a wider value range of correlation coefficient for reliability analysis is confirmed and an acceptable accuracy can be obtained with less computational cost.
基金Supported by Scientific Research Foundation of Health Department of Shaanxi Province(2012D14),China
文摘OBJECTIVE:To optimize the vinegar-steaming process of Wuweizi(Fructus Schisandrae Chinensis)using the response surface method(RSM)based on the Box-Behnken design.METHODS:A regression model was constructed with the response variables,the content of Deoxyschizandrin,and the three explanatory factors:length of steaming time,the quantity of vinegar and length of moistening time to evaluate the effects on the processing of Wuweizi(Fructus SchisandraeChinensis).RESULTS:There was a linear relationship between the content of Deoxyschizandrin and the three explanatory factors.When the steaming time was5.49 h,with 2.365 g of vinegar added and a moistening time of 4.13 h,the content of Deoxyschizandrin reached the maximum predicted value of0.1076%,and under the conditions the average content of Deoxyschizandrin was 0.1058%.CONCLUSION:The correlation coefficient of thenonlinear mathematical model was relatively high and the model matched the data well,potentially providing a method for the study of the steaming process.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51508107)the China Postdoctoral Science Foundation(Grant No.2016M590592)the Natural Science Foundation of Fujian Province(Grant No.2015J05098)。
文摘According to the relationship between load and response, the equivalent static wind load(ESWL) of a structure can be estimated by load-response correlation(LRC) method, which can be accurately used to estimate the background ESWL of a structure. The derivation of the classical expression of LRC formula is based on a specific command response at a critical position, and the ESWL distribution has only one form in this case. In this paper, a general expression of LRC formula is derived based on a specific command response at all positions. For the general expression, ESWLs can be expressed by load-response correlation coefficients, response-response correlation coefficients, RMS values of the fluctuating wind loads, and peak factor in the form of matrices. By comparing the expressions of LRC method, it was found that the classical expression was only one form of the general one. The general expression which introduces the response-response correlation coefficients provided more options for structural engineers to estimate ESWLs and offered further insights into the LRC method. Finally, a cable-stayed bridge, a rigid three span continuous girder bridge, and a suspension bridge were used to verify the correctness of the general expression of LRC method.
基金This research was funded by the National Natural Science Foundation under Grant No.[41974151]by the Jiangsu Province Natural Science Foundation under Grant No.[BK20181360]+1 种基金by the Major Scientific and Technological Innovation Project of Shandong Province of China under Grant No.[2019JZZY010820]by the Shaanxi Province Science and Technology Innovation Guidance Special No.[2020CGHJ-005].
文摘The complex resistivity of coal and related rocks contains abundant physical property information,which can be indirectly used to study the lithology and microstructure of these materials.These aspects are closely related to the fluids inside the considered coal rocks,such as gas,water and coalbed methane.In the present analysis,considering different lithological structures,and using the Cole-Cole model,a forward simulation method is used to study different physical parameters such as the zero-frequency resistivity,the polarizability,the relaxation time,and the frequency correlation coefficient.Moreover,using a least square technique,a complex resistivity“inversion”algorithm is written.The comparison of the initial model parameters and those obtained after inversion is used to verify the stability and accuracy of such approach.The method is finally applied to primary-structure coal considered as the experimental sample for complex resistivity measurements.
文摘Applied statisticians are often confronted with statistical inference problems dealing with situations in which there appear to be no data,or data of only limited usefulness.For example,when attempting to find a confidence interval for a binomial proportion,the sample may contain no successes.Such a scenario could be encountered when attempting to estimate the incidence of an extremely rare side effect associated with the administration of a newly developed drug.In this article,we use examples for our experiences working with scientific investigators and describe several scenarios in which there appeared to be no useful data,or data of only limited usefulness.We describe the methods we prefer for analyzing the data in these situations and illustrate their application using the actual data from the investigations we participated in.
文摘This article aimed to find a new way to transform the graphic image (drawing, photos, etc) to the pattern parameters of female apparel with raglan sleeve. The correlation and regressive analysis were used to the data in order to find the existing laws between them. The practical examinations demonstrated the good predictability of equations established.
文摘为快速、准确预测接触网复合绝缘子临界污闪电压,减少人工污秽试验工作量,提出了一种复合绝缘子污秽闪络电压预测模型。首先,利用黄金正弦(golden sine algorithm,GSA)与分段线性混沌映射(piecewise linear chaotic map,PWLCM)改进的减法平均优化器(subtraction average based optimizer,SABO)算法增强反向传播(back propagation,BP)神经网络的性能;其次,利用人工污秽试验获取10种不同复合绝缘子的闪络电压,收集相关试验参数;再次,依据Obenaus模型对复合绝缘子污秽闪络表现进行分析,利用斯皮尔曼(Spearman)相关系数法筛选出与复合绝缘子临界污闪电压密切相关的4个参数作为预测模型的输入特征量,以预测复合绝缘子临界污闪电压;最后,利用五折交叉验证法对预测模型进行综合评估,并与常用智能优化算法预测模型的预测结果进行比较。结果表明:GSABO-BP模型预测复合绝缘子污闪电压平均绝对误差为1.244 kV,平均绝对百分比误差为2.25%,模型可决系数稳定在0.98以上;与改进前的SABO-BP模型相比,预测值平均误差下降67.80%。GSABO-BP模型在复合绝缘子污闪电压预测上具有较高的预测精准度,对电气化铁路供电系统的防污保护工作具有重要意义。
