Taking into account the characteristics of non-Newtonian fluids and the influence of latent heat of wax crystallization,this study establishes physical and mathematical models for the synergy of tubular heating and me...Taking into account the characteristics of non-Newtonian fluids and the influence of latent heat of wax crystallization,this study establishes physical and mathematical models for the synergy of tubular heating and mechanical stirring during the waxy crude oil heating process.Numerical calculations are conducted using the sliding grid technique and FVM.The focus of this study is on the impact of stirring rate(τ),horizontal deflection angle(θ1),vertical deflection angle(θ2),and stirring diameter(D)on the heating effect of crude oil.Our results show that asτincreases from 200 rpm to 500 rpm and D increases from 400 mm to 600 mm,there is an improvement in the average crude oil temperature and temperature uniformity.Additionally,heating efficiency increases by 0.5%and 1%,while the volume of the low-temperature region decreases by 57.01 m^(3) and 36.87 m3,respectively.Asθ1 andθ2 increase from 0°to 12°,the average crude oil temperature,temperature uniformity,and heating efficiency decrease,while the volume of the low-temperature region remains basically the same.Grey correlation analysis is used to rank the importance of stirring parameters in the following order:τ>θ1>θ2>D.Subsequently,multiple regression analysis is used to quantitatively describe the relationship between different stirring parameters and heat transfer evaluation indices through equations.Finally,based on entropy generation minimization,the stirring parameters with optimal heat transfer performance are obtained when τ=350 rpm,θ1=θ2=0°,and D=500 mm.展开更多
The concept of average incremental correlation degree is put forward.It has been proved that the average incremental correlation model has such properties as parallelism,consistency,affine,affine transformation isoton...The concept of average incremental correlation degree is put forward.It has been proved that the average incremental correlation model has such properties as parallelism,consistency,affine,affine transformation isotonicity and interference factors independence,and it will not lead to changes of the sequence order relation because of the data transformation.Therefore,the new model keeps good stability.Finally,the incremental average correlation model is applied to failure model analysis of equipment,and an ideal diagnostic effect is obtained.展开更多
One of the primary forestry research interests lies in estimating forest stand parameters by applying empirical or semi-empirical model to establish the relationship between the forest stand parameters and remote sens...One of the primary forestry research interests lies in estimating forest stand parameters by applying empirical or semi-empirical model to establish the relationship between the forest stand parameters and remote sensing data. Using remote sensing image and the inventory data from 2 compartments in northeast Florida, U.S.A., this paper explored the correlation between forest stand parameters and Landsat TM spectral digital number （DN） value. Results showed that less than 50% of the total variance could be explained by linear regression models with only either a single band or such vegetation indices as vegetation index （VI） or normalized difference vegetation index （NDVI） as predicators. In consequence, multi-linear regression models which synthesized more predicators were introduced to estimate forest parameters. Regression results were tested in terms of the other group of data, and verification showed a better capability of explaining over 75% variance except for forest density. The weakness and further improvement of prediction models were also discussed in the article. This paper is expected to provide a better understanding of the relationship between TM spectral and forest characteristics展开更多
The difficulties associated with performing direct compression strength tests on rocks lead to the development of indirect test methods for the rock strength assessment. Indirect test methods are simple, more economic...The difficulties associated with performing direct compression strength tests on rocks lead to the development of indirect test methods for the rock strength assessment. Indirect test methods are simple, more economical, less time-consuming, and easily adaptable to the field. The main aim of this study was to derive correlations between direct and indirect test methods for basalt and rhyolite rock types from Carlin trend deposits in Nevada. In the destructive methods, point load index, block punch index, and splitting tensile strength tests are performed. In the non-destructive methods, Schmidt hammer and ultrasonic pulse velocity tests are performed. Correlations between the direct and indirect compression strength tests are developed using linear and nonlinear regression analysis methods. The results show that the splitting tensile strength has the best correlation with the uniaxial compression strength.Furthermore, the Poisson's ratio has no correlation with any of the direct and indirect test results.展开更多
This thesis offers the general concept of coefficient of partial correlation.Starting with regres-sion analysis,the paper,by using samples,infers the general formula of expressing coefficient of partial correlation by...This thesis offers the general concept of coefficient of partial correlation.Starting with regres-sion analysis,the paper,by using samples,infers the general formula of expressing coefficient of partial correlation by way of simple correlation coefficient.展开更多
目的:分析脓毒症肺损伤中医证型与生存结局之间的相关性。方法:回顾性分析山东中医药大学附属医院急诊重症医学科确诊的脓毒症肺损伤住院患者病历,危险因素包括年龄、感染部位、既往史、最高体温、白细胞计数、降钙素原、血乳酸、急性...目的:分析脓毒症肺损伤中医证型与生存结局之间的相关性。方法:回顾性分析山东中医药大学附属医院急诊重症医学科确诊的脓毒症肺损伤住院患者病历,危险因素包括年龄、感染部位、既往史、最高体温、白细胞计数、降钙素原、血乳酸、急性生理与慢性健康评分(acute physiology and chronic health evaluationⅡ,APACHEⅡ),通过Kaplan-Meier和单因素Cox比例风险回归分析比较中医证型及各危险因素与患者短期、长期预后的相关性。结果:热毒闭肺证、肺热腑实证、正虚喘脱证患者14天短期预后无明显差异(P=0.746),长期预后显示年龄、既往史、血乳酸、APACHEⅡ评分和中医辨证分型是影响脓毒症肺损伤患者预后的危险因素;肺热腑实证和正虚喘脱证死亡风险均高于热毒闭肺证(HR=4.127,95%CI[1.967,8.658],P<0.001;HR=5.455,95%CI[2.665,11.167],P<0.001),肺热腑实证与正虚喘脱证死亡风险比较无差异(OR=0.613,95%CI[0.272,1,387],P>0.05)。结论:中医证型与脓毒症肺损伤的预后具有相关性。展开更多
基金supported by the National Natural Science Foundation of China(Grant no.52304065)China Postdoctoral Science Foundation(Grant no.2022MD723759).
文摘Taking into account the characteristics of non-Newtonian fluids and the influence of latent heat of wax crystallization,this study establishes physical and mathematical models for the synergy of tubular heating and mechanical stirring during the waxy crude oil heating process.Numerical calculations are conducted using the sliding grid technique and FVM.The focus of this study is on the impact of stirring rate(τ),horizontal deflection angle(θ1),vertical deflection angle(θ2),and stirring diameter(D)on the heating effect of crude oil.Our results show that asτincreases from 200 rpm to 500 rpm and D increases from 400 mm to 600 mm,there is an improvement in the average crude oil temperature and temperature uniformity.Additionally,heating efficiency increases by 0.5%and 1%,while the volume of the low-temperature region decreases by 57.01 m^(3) and 36.87 m3,respectively.Asθ1 andθ2 increase from 0°to 12°,the average crude oil temperature,temperature uniformity,and heating efficiency decrease,while the volume of the low-temperature region remains basically the same.Grey correlation analysis is used to rank the importance of stirring parameters in the following order:τ>θ1>θ2>D.Subsequently,multiple regression analysis is used to quantitatively describe the relationship between different stirring parameters and heat transfer evaluation indices through equations.Finally,based on entropy generation minimization,the stirring parameters with optimal heat transfer performance are obtained when τ=350 rpm,θ1=θ2=0°,and D=500 mm.
基金supported by Marie Curie International Incoming Fellowship within the 7th European Community Framework Programme (Grant No.FP7-PIIF-GA-2013629051)the National Natural Science Foundation of China (No.91324003)Social Science Foundation of the China(10zd&014,12AZD102)
文摘The concept of average incremental correlation degree is put forward.It has been proved that the average incremental correlation model has such properties as parallelism,consistency,affine,affine transformation isotonicity and interference factors independence,and it will not lead to changes of the sequence order relation because of the data transformation.Therefore,the new model keeps good stability.Finally,the incremental average correlation model is applied to failure model analysis of equipment,and an ideal diagnostic effect is obtained.
文摘One of the primary forestry research interests lies in estimating forest stand parameters by applying empirical or semi-empirical model to establish the relationship between the forest stand parameters and remote sensing data. Using remote sensing image and the inventory data from 2 compartments in northeast Florida, U.S.A., this paper explored the correlation between forest stand parameters and Landsat TM spectral digital number （DN） value. Results showed that less than 50% of the total variance could be explained by linear regression models with only either a single band or such vegetation indices as vegetation index （VI） or normalized difference vegetation index （NDVI） as predicators. In consequence, multi-linear regression models which synthesized more predicators were introduced to estimate forest parameters. Regression results were tested in terms of the other group of data, and verification showed a better capability of explaining over 75% variance except for forest density. The weakness and further improvement of prediction models were also discussed in the article. This paper is expected to provide a better understanding of the relationship between TM spectral and forest characteristics
基金CDC/NIOSH for their partial funding of this work
文摘The difficulties associated with performing direct compression strength tests on rocks lead to the development of indirect test methods for the rock strength assessment. Indirect test methods are simple, more economical, less time-consuming, and easily adaptable to the field. The main aim of this study was to derive correlations between direct and indirect test methods for basalt and rhyolite rock types from Carlin trend deposits in Nevada. In the destructive methods, point load index, block punch index, and splitting tensile strength tests are performed. In the non-destructive methods, Schmidt hammer and ultrasonic pulse velocity tests are performed. Correlations between the direct and indirect compression strength tests are developed using linear and nonlinear regression analysis methods. The results show that the splitting tensile strength has the best correlation with the uniaxial compression strength.Furthermore, the Poisson's ratio has no correlation with any of the direct and indirect test results.
文摘This thesis offers the general concept of coefficient of partial correlation.Starting with regres-sion analysis,the paper,by using samples,infers the general formula of expressing coefficient of partial correlation by way of simple correlation coefficient.
文摘目的:分析脓毒症肺损伤中医证型与生存结局之间的相关性。方法:回顾性分析山东中医药大学附属医院急诊重症医学科确诊的脓毒症肺损伤住院患者病历,危险因素包括年龄、感染部位、既往史、最高体温、白细胞计数、降钙素原、血乳酸、急性生理与慢性健康评分(acute physiology and chronic health evaluationⅡ,APACHEⅡ),通过Kaplan-Meier和单因素Cox比例风险回归分析比较中医证型及各危险因素与患者短期、长期预后的相关性。结果:热毒闭肺证、肺热腑实证、正虚喘脱证患者14天短期预后无明显差异(P=0.746),长期预后显示年龄、既往史、血乳酸、APACHEⅡ评分和中医辨证分型是影响脓毒症肺损伤患者预后的危险因素;肺热腑实证和正虚喘脱证死亡风险均高于热毒闭肺证(HR=4.127,95%CI[1.967,8.658],P<0.001;HR=5.455,95%CI[2.665,11.167],P<0.001),肺热腑实证与正虚喘脱证死亡风险比较无差异(OR=0.613,95%CI[0.272,1,387],P>0.05)。结论:中医证型与脓毒症肺损伤的预后具有相关性。
