A method is presented that coordinates the calculation of the displacement, velocity and acceleration of structures within the time-steps of different types of step-by-step integration. The dynamic equation is solved ...A method is presented that coordinates the calculation of the displacement, velocity and acceleration of structures within the time-steps of different types of step-by-step integration. The dynamic equation is solved using an energy equation and the calculating data of the original method. The method presented is better than the original method in terms of calculating postulations and is in better conformity with the system's movement. Take the Wilson-θ method as an example. By using the coordination process, the calculation precision has been greatly im proved (reducing the errors by approximately 90% ), and the greater part of overshooting of the calculation result has been eliminated. The study suggests that the mal-coordination of the motion parameters within the time-step is the major factor that contributes to the result errors of step-by-step integration for the dynamic equation.展开更多
A simple algorithm is proposed for step-by-step time integration of stiff ODEs in Chemical Kinetics. No predictor-corrector technique is used within each step of the algorithm. It is assumed that species concentration...A simple algorithm is proposed for step-by-step time integration of stiff ODEs in Chemical Kinetics. No predictor-corrector technique is used within each step of the algorithm. It is assumed that species concentrations less than 10-6 mol·L-1 do not activate any chemical reaction. So, within each step, the time steplength Δt of the algorithm is determined from the fastest reaction rate maxR by the formula Δt = 10-6mol·L-1/max R. All the reversible elementary reactions occur simultaneously;however, by a simple book-keeping technique, the updating of species concentrations, within each step of the algorithm, is performed within each elementary reaction separately. The above proposed simple algorithm for Chemical Kinetics is applied to a simple model for hydrogen combustion with only five reversible elementary reactions (Initiation, Propagation, First and Second Branching, Termination by wall destruction) with six species (H2, O2, H, O, HO, H2O). These five reversible reactions are recommended in the literature as the most significant elementary reactions of hydrogen combustion [1] [2]. Based on the proposed here simple algorithm for Chemical Kinetics, applied to the global mechanism of proposed five reversible elementary reactions for hydrogen combustion, a simple and short computer program has been developed with only about 120 Fortran instructions. By this proposed program, the following are obtained: 1) The total species concentration of hydrogen combustion, starting from the sum of initial reactants concentrations [H2] + [O2], gradually diminishes, due to termination reaction by wall destruction, and tends to the final concentration of the product [H2O], that is to the 2/3 of its initial value, in accordance to the established overall stoichiometric reaction of hydrogen combustion 2H2 + O2 → 2H2O. 2) Time-histories for concentrations of main species H2, O2, H, H2O of hydrogen combustion, in explosion and equilibrium regions, obtained by the proposed program, are compared to corresponding ones obtained by accurate computational studies of [3]. 3) In the first step of the algorithm, the only nonzero species concentrations are those of reactants [H2], [O2]. So, the maximum reaction rate is that of the forward initiation reaction max R = Rif = kif[H2] [O2], where the rate constant kif is very slow. Thus, the first time steplength Δt1 = 10-6mol·L-1/max R results long in sec. After the first step, the sequences of all the following Δt’s are very short, in μsec. So, the first time steplength Δt1 can be considered as ignition delay time. 4) It is assumed that explosion corresponds to ignition delay time Δt1 t1 = 10 sec., can be considered as explosion limit curve. This curve is compared to the corresponding one obtained by the accurate computational studies of [2].展开更多
This paper presents a finite element procedure for solving transient, multidimensional convection-diffusion equations. The procedure is based on the characteristic Galerkin method with an implicit algorithm using prec...This paper presents a finite element procedure for solving transient, multidimensional convection-diffusion equations. The procedure is based on the characteristic Galerkin method with an implicit algorithm using precise integration method. With the operator splitting procedure, the precise integration method is introduced to determine the material derivative in the convection-diffusion equation, consequently, the physical quantities of material points. An implicit algorithm with a combination of both the precise and the traditional numerical integration procedures in time domain in the Lagrange coordinates for the characteristic Galerkin method is formulated. The stability analysis of the algorithm shows that the unconditional stability of present implicit algorithm is enhanced as compared with that of the traditional implicit numerical integration procedure. The numerical results validate the presented method in solving convection-diffusion equations. As compared with SUPG method and explicit characteristic Galerkin method, the present method gives the results with higher accuracy and better stability.展开更多
A new approach which is a direct integration method with integral model (DIM-IM) to solve dynamic governing equations is presented. The governing equations ore integrated into the integral equations. An algorithm with...A new approach which is a direct integration method with integral model (DIM-IM) to solve dynamic governing equations is presented. The governing equations ore integrated into the integral equations. An algorithm with explicit and predict-correct and self-starting and fourth-order accuracy to integrate the integral equations is given. Theoretical analysis and numerical examples shaw that DIM-IM described in this paper suitable for strong nonlinear and non-conservative system have higher accuracy than central difference, Houbolt, Newmark and Wilson-Theta methods.展开更多
A new active control method was proposed, in which the analytical control law was deduced by using a step by step integral method to differential equation of motion under the condition of static error being zero. This...A new active control method was proposed, in which the analytical control law was deduced by using a step by step integral method to differential equation of motion under the condition of static error being zero. This control law is terse in mathematical expression and convenient for practical use. The simulation results demonstrate that the proposed method can provide much more remarkable peak response reduction of seismically excited structures than the classical LQR method.展开更多
BACKGROUND Internal rectal prolapse(IRP)is one of the most common causes of obstructive constipation.The incidence of IRP in women is approximately three times that in men.IRP is mainly treated by surgery,which can be...BACKGROUND Internal rectal prolapse(IRP)is one of the most common causes of obstructive constipation.The incidence of IRP in women is approximately three times that in men.IRP is mainly treated by surgery,which can be divided into two categories:Abdominal procedures and perineal procedures.This study offers a better procedure for the treatment of IRP.AIM To compare the clinical efficacy of laparoscopic integral pelvic floor/ligament repair(IPFLR)combined with a procedure for prolapse and hemorrhoids(PPH)and the laparoscopic IPFLR alone in the treatment of IRP in women.METHODS This study collected the clinical data of 130 female patients with IRP who underwent surgery from January 2012 to October 2014.The patients were divided into groups A and B.Group A had 63 patients who underwent laparoscopic IPFLR alone,and group B had 67 patients who underwent the laparoscopic IPFLR combined with PPH.The degree of internal rectal prolapse(DIRP),Wexner constipation scale(WCS)score,Wexner incontinence scale(WIS)score,and Gastrointestinal Quality of Life Index(GIQLI)score were compared between groups and within groups before surgery and 6 mo and 2 years after surgery.RESULTS All laparoscopic surgeries were successful.The general information,number of bowel movements before surgery,DIRP,GIQLI score,WIS score,and WCS score before surgery were not significantly different between the two groups(all P>0.05).The WCS score,WIS score,GIQLI score,and DIRP in each group 6 mo,and 2 years after surgery were significantly better than before surgery(P<0.001).In group A,the DIRP and WCS score gradually improved from 6 mo to 2 years after surgery(P<0.001),and the GIQLI score progressively improved from 6 mo to 2 years after surgery(P<0.05).In group B,the DIRP,WCS score and WIS score significantly improved from 6 mo to 2 years after surgery(P<0.05),and the GIQLI score 2 years after surgery was significantly higher than that 6 mo after surgery(P<0.05).The WCS score,WIS score,GIQLI score,and DIRP of group B were significantly better than those of group A 6 mo and 2 years after surgery(all P<0.001,Bonferroni)except DIRP at 2 years after surgery.There was a significant difference in the recurrence rate of IRP between the two groups 6 mo after surgery(P=0.011).There was no significant difference in postoperative grade I-III complications between the two groups(P=0.822).CONCLUSION Integral theory–guided laparoscopic IPFLR combined with PPH has a higher cure rate and a better clinical efficacy than laparoscopic IPFLR alone.展开更多
New hierarchical direct time integration method for structural dynamic analysis is developed by using Taylor series expansions in each time step. Very accurate results can be obtained by increasing the order of the Ta...New hierarchical direct time integration method for structural dynamic analysis is developed by using Taylor series expansions in each time step. Very accurate results can be obtained by increasing the order of the Taylor series. Furthermore, the local error can be estimated by simply comparing the solutions obtained by the proposed method with the higher order solutions. This local estimate is then used to develop an adaptive order control technique. Numerical examples are given to illustrate the performance of the present method and its adaptive procedure.展开更多
The use of multiple-choice(MC)question types has been one of the most contentious issues in language testing.Much has been said and written about the use of MC over the years.However,no attempt has ever been made to i...The use of multiple-choice(MC)question types has been one of the most contentious issues in language testing.Much has been said and written about the use of MC over the years.However,no attempt has ever been made to introduce any innovation in test item types.The researchers proposed a jumbled words test item(JW)based on cognitive science and deep learning principles,and addressed the feasibility of replacing the type of multiple-choice(MC)question with JW to meet the ongoing rapid development of language testing practice.Two research questions were proposed ad hoc,focusing on the co-relationship between JW and MC scores.RASCH-GZ was used to perform item analyses(Rasch,1960).The item difficulty parameters thus obtained were used to compare the two different test items.The sample data metric includes 40 Chinese participants.The findings revealed that correlation analysis revealed that the performance of the same group of subjects taking both JW and MC was not relevant(Pearson Corr=0).This is primarily due to the total elimination of guessing factors inherent in test-takers during JW test performance.Three factors were specified for the design of the JW test:compute program,test difficulty,and score acceptability.These all have three dimensions.Data collected through questionnaires were analyzed using EFA in SPSS V.24.0.KMOs(=0.867)were found to be approximately one and significance at 0.000(0.05),indicating that the construct of theuestionnaire thus designed has better validity for factor analysis.Three important conclusions were obtained,the implications of which could provide impetus for our testing counterparts to practice more precisely and correctly,potentially reshaping our overall language testing practice.Limitations and recommendations for future research were also discussed.展开更多
文摘A method is presented that coordinates the calculation of the displacement, velocity and acceleration of structures within the time-steps of different types of step-by-step integration. The dynamic equation is solved using an energy equation and the calculating data of the original method. The method presented is better than the original method in terms of calculating postulations and is in better conformity with the system's movement. Take the Wilson-θ method as an example. By using the coordination process, the calculation precision has been greatly im proved (reducing the errors by approximately 90% ), and the greater part of overshooting of the calculation result has been eliminated. The study suggests that the mal-coordination of the motion parameters within the time-step is the major factor that contributes to the result errors of step-by-step integration for the dynamic equation.
文摘A simple algorithm is proposed for step-by-step time integration of stiff ODEs in Chemical Kinetics. No predictor-corrector technique is used within each step of the algorithm. It is assumed that species concentrations less than 10-6 mol·L-1 do not activate any chemical reaction. So, within each step, the time steplength Δt of the algorithm is determined from the fastest reaction rate maxR by the formula Δt = 10-6mol·L-1/max R. All the reversible elementary reactions occur simultaneously;however, by a simple book-keeping technique, the updating of species concentrations, within each step of the algorithm, is performed within each elementary reaction separately. The above proposed simple algorithm for Chemical Kinetics is applied to a simple model for hydrogen combustion with only five reversible elementary reactions (Initiation, Propagation, First and Second Branching, Termination by wall destruction) with six species (H2, O2, H, O, HO, H2O). These five reversible reactions are recommended in the literature as the most significant elementary reactions of hydrogen combustion [1] [2]. Based on the proposed here simple algorithm for Chemical Kinetics, applied to the global mechanism of proposed five reversible elementary reactions for hydrogen combustion, a simple and short computer program has been developed with only about 120 Fortran instructions. By this proposed program, the following are obtained: 1) The total species concentration of hydrogen combustion, starting from the sum of initial reactants concentrations [H2] + [O2], gradually diminishes, due to termination reaction by wall destruction, and tends to the final concentration of the product [H2O], that is to the 2/3 of its initial value, in accordance to the established overall stoichiometric reaction of hydrogen combustion 2H2 + O2 → 2H2O. 2) Time-histories for concentrations of main species H2, O2, H, H2O of hydrogen combustion, in explosion and equilibrium regions, obtained by the proposed program, are compared to corresponding ones obtained by accurate computational studies of [3]. 3) In the first step of the algorithm, the only nonzero species concentrations are those of reactants [H2], [O2]. So, the maximum reaction rate is that of the forward initiation reaction max R = Rif = kif[H2] [O2], where the rate constant kif is very slow. Thus, the first time steplength Δt1 = 10-6mol·L-1/max R results long in sec. After the first step, the sequences of all the following Δt’s are very short, in μsec. So, the first time steplength Δt1 can be considered as ignition delay time. 4) It is assumed that explosion corresponds to ignition delay time Δt1 t1 = 10 sec., can be considered as explosion limit curve. This curve is compared to the corresponding one obtained by the accurate computational studies of [2].
文摘This paper presents a finite element procedure for solving transient, multidimensional convection-diffusion equations. The procedure is based on the characteristic Galerkin method with an implicit algorithm using precise integration method. With the operator splitting procedure, the precise integration method is introduced to determine the material derivative in the convection-diffusion equation, consequently, the physical quantities of material points. An implicit algorithm with a combination of both the precise and the traditional numerical integration procedures in time domain in the Lagrange coordinates for the characteristic Galerkin method is formulated. The stability analysis of the algorithm shows that the unconditional stability of present implicit algorithm is enhanced as compared with that of the traditional implicit numerical integration procedure. The numerical results validate the presented method in solving convection-diffusion equations. As compared with SUPG method and explicit characteristic Galerkin method, the present method gives the results with higher accuracy and better stability.
文摘A new approach which is a direct integration method with integral model (DIM-IM) to solve dynamic governing equations is presented. The governing equations ore integrated into the integral equations. An algorithm with explicit and predict-correct and self-starting and fourth-order accuracy to integrate the integral equations is given. Theoretical analysis and numerical examples shaw that DIM-IM described in this paper suitable for strong nonlinear and non-conservative system have higher accuracy than central difference, Houbolt, Newmark and Wilson-Theta methods.
文摘A new active control method was proposed, in which the analytical control law was deduced by using a step by step integral method to differential equation of motion under the condition of static error being zero. This control law is terse in mathematical expression and convenient for practical use. The simulation results demonstrate that the proposed method can provide much more remarkable peak response reduction of seismically excited structures than the classical LQR method.
基金Supported by Medical Science and Technology Project of Henan Province,China,No.2011030031.
文摘BACKGROUND Internal rectal prolapse(IRP)is one of the most common causes of obstructive constipation.The incidence of IRP in women is approximately three times that in men.IRP is mainly treated by surgery,which can be divided into two categories:Abdominal procedures and perineal procedures.This study offers a better procedure for the treatment of IRP.AIM To compare the clinical efficacy of laparoscopic integral pelvic floor/ligament repair(IPFLR)combined with a procedure for prolapse and hemorrhoids(PPH)and the laparoscopic IPFLR alone in the treatment of IRP in women.METHODS This study collected the clinical data of 130 female patients with IRP who underwent surgery from January 2012 to October 2014.The patients were divided into groups A and B.Group A had 63 patients who underwent laparoscopic IPFLR alone,and group B had 67 patients who underwent the laparoscopic IPFLR combined with PPH.The degree of internal rectal prolapse(DIRP),Wexner constipation scale(WCS)score,Wexner incontinence scale(WIS)score,and Gastrointestinal Quality of Life Index(GIQLI)score were compared between groups and within groups before surgery and 6 mo and 2 years after surgery.RESULTS All laparoscopic surgeries were successful.The general information,number of bowel movements before surgery,DIRP,GIQLI score,WIS score,and WCS score before surgery were not significantly different between the two groups(all P>0.05).The WCS score,WIS score,GIQLI score,and DIRP in each group 6 mo,and 2 years after surgery were significantly better than before surgery(P<0.001).In group A,the DIRP and WCS score gradually improved from 6 mo to 2 years after surgery(P<0.001),and the GIQLI score progressively improved from 6 mo to 2 years after surgery(P<0.05).In group B,the DIRP,WCS score and WIS score significantly improved from 6 mo to 2 years after surgery(P<0.05),and the GIQLI score 2 years after surgery was significantly higher than that 6 mo after surgery(P<0.05).The WCS score,WIS score,GIQLI score,and DIRP of group B were significantly better than those of group A 6 mo and 2 years after surgery(all P<0.001,Bonferroni)except DIRP at 2 years after surgery.There was a significant difference in the recurrence rate of IRP between the two groups 6 mo after surgery(P=0.011).There was no significant difference in postoperative grade I-III complications between the two groups(P=0.822).CONCLUSION Integral theory–guided laparoscopic IPFLR combined with PPH has a higher cure rate and a better clinical efficacy than laparoscopic IPFLR alone.
文摘New hierarchical direct time integration method for structural dynamic analysis is developed by using Taylor series expansions in each time step. Very accurate results can be obtained by increasing the order of the Taylor series. Furthermore, the local error can be estimated by simply comparing the solutions obtained by the proposed method with the higher order solutions. This local estimate is then used to develop an adaptive order control technique. Numerical examples are given to illustrate the performance of the present method and its adaptive procedure.
文摘The use of multiple-choice(MC)question types has been one of the most contentious issues in language testing.Much has been said and written about the use of MC over the years.However,no attempt has ever been made to introduce any innovation in test item types.The researchers proposed a jumbled words test item(JW)based on cognitive science and deep learning principles,and addressed the feasibility of replacing the type of multiple-choice(MC)question with JW to meet the ongoing rapid development of language testing practice.Two research questions were proposed ad hoc,focusing on the co-relationship between JW and MC scores.RASCH-GZ was used to perform item analyses(Rasch,1960).The item difficulty parameters thus obtained were used to compare the two different test items.The sample data metric includes 40 Chinese participants.The findings revealed that correlation analysis revealed that the performance of the same group of subjects taking both JW and MC was not relevant(Pearson Corr=0).This is primarily due to the total elimination of guessing factors inherent in test-takers during JW test performance.Three factors were specified for the design of the JW test:compute program,test difficulty,and score acceptability.These all have three dimensions.Data collected through questionnaires were analyzed using EFA in SPSS V.24.0.KMOs(=0.867)were found to be approximately one and significance at 0.000(0.05),indicating that the construct of theuestionnaire thus designed has better validity for factor analysis.Three important conclusions were obtained,the implications of which could provide impetus for our testing counterparts to practice more precisely and correctly,potentially reshaping our overall language testing practice.Limitations and recommendations for future research were also discussed.
