A new form function involving parameters Pi is presented. On the basis of the form function, an initial form of tension structure was Sound by interpolating through the control points on boundary of the structure. The...A new form function involving parameters Pi is presented. On the basis of the form function, an initial form of tension structure was Sound by interpolating through the control points on boundary of the structure. The form function can be controlled by changing beta (1) according to the pre-tension and the boundary of the structure. The final form of a tension structure should be an equilibrium system under the pretension. To examine the nature of the initial form, the FEM was used. Many examples show that the initial form gives a very ideal result for equal or unequal pre-tension in two directions of the structure. In general cases, there is little difference between the initial form and the final one.展开更多
In this paper,such a new lateral displacement function is proposed that the lateral flow velocity is con- tinuous at the entry and the exit of deformation zone.A new kind of finite strip method—the third power B-spli...In this paper,such a new lateral displacement function is proposed that the lateral flow velocity is con- tinuous at the entry and the exit of deformation zone.A new kind of finite strip method—the third power B-spline finite strip method—is put forward to simulate strip rolling process.Front and back tension stresses are formulated.The computed results of the transverse distributions of the front and back tension stresses are close to the experimental results.The paper lays a foundation for further analysing the three-dimensional stresses and deformations of strip rolling.展开更多
In this paper the results of a high-speed tension experiment of the SiC_w/Al composite have been reported and a simplified theoretical model has been developed to study the fracture mechanism of composites in high-spe...In this paper the results of a high-speed tension experiment of the SiC_w/Al composite have been reported and a simplified theoretical model has been developed to study the fracture mechanism of composites in high-speed tension. This theoretical model provides a new explanation for the increase of dynamic fracture strength of composites in high-speed tension.展开更多
Background: Children are affected by disorders that have an impact on the respiratory muscles. Inspiratory muscle function can be assessed by means of the noninvasive tension–time index of the inspiratory muscles(TTI...Background: Children are affected by disorders that have an impact on the respiratory muscles. Inspiratory muscle function can be assessed by means of the noninvasive tension–time index of the inspiratory muscles(TTImus). Our objectives were to identify the determinants of TTImus in healthy children and to report normal values of TTImus in this population.Methods: We measured weight, height, upper arm muscle area(UAMA), and TTImusin 96 children aged 6–18 years. The level and frequency of aerobic activity was assessed by questionnaire.Results: TTImuswas significantly lower in male subjects(0.095 ± 0.038, mean ± SD) compared with female subjects(0.126 ± 0.056)(p = 0.002).TTImus was significantly lower in regularly exercising(0.093 ± 0.040) compared with nonexercising subjects(0.130 ± 0.053)(p < 0.001). TTImus was significantly negatively related to age(r =-0.239, p = 0.019), weight(r =-0.214, p = 0.037), height(r =-0.355, p < 0.001), and UAMA(r =-0.222, p = 0.030). Multivariate logistic regression analysis revealed that height and aerobic exercise were significantly related to TTImus independently of age, weight, and UAMA. The predictive regression equation for TTImus in male subjects was TTImus = 0.228-0.001 × height(cm), and in female subjects it was TTImus = 0.320-0.001 × height(cm).Conclusion: Gender, age, anthropometry, skeletal muscularity, and aerobic exercise are significantly associated with indices of inspiratory muscle function in children. Normal values of TTImus in healthy children are reported.展开更多
In this paper a method has been proposed for the calculation of cohesive work and thus sur-face tension of liquids by the Monte Carlo computer simulation method with the use of Kihara po-tential. The surface tension v...In this paper a method has been proposed for the calculation of cohesive work and thus sur-face tension of liquids by the Monte Carlo computer simulation method with the use of Kihara po-tential. The surface tension values calculated for liquid argon, oxygen and nitrogen are in fairagreement with the experimental data.展开更多
The statistical and distribution characteristics of the responses of a floater and its mooring lines are essential in designing floating/mooring systems.In general,the dynamic responses of offshore structures obey a G...The statistical and distribution characteristics of the responses of a floater and its mooring lines are essential in designing floating/mooring systems.In general,the dynamic responses of offshore structures obey a Gaussian distribution,assuming that the structural system,and sea loads are linear or weakly nonlinear.However,mooring systems and wave loads are considerably nonlinear,and the dynamic responses of hull/mooring systems are non-Gaussian.In this study,the dynamic responses of two types of floaters,semi-submersible and spar platforms,and their mooring lines are computed using coupled dynamic analysis in the time domain.Herein,the statistical characteristics and distributions of the hull motion and mooring line tension are discussed and compared.The statistical distributions of the dynamic responses have strong non-Gaussianity and are unreasonably fitted by a Gaussian distribution for the two floating and mooring systems.Then,the effects of water depth,wave parameters,and low-frequency and wave-frequency components on the non-Gaussianity of the hull motion,and mooring line tension are investigated and discussed.A comparison of the statistical distributions of the responses with various probability density functions,including the Gamma,Gaussian,General Extreme Value,Weibull,and Gaussian Mixture Model(GMM)distributions,shows that the GMM distribution is better than the others for characterizing the statistical distributions of the hull motion,and mooring line tension responses.Furthermore,the GMM distribution has the best accuracy of response prediction.展开更多
The interstand tension control is one of the most important ways to meet tight tolerances for strip product quality during tandem cold rolling process. Using coordinate analysis and parabolic approximation for the mas...The interstand tension control is one of the most important ways to meet tight tolerances for strip product quality during tandem cold rolling process. Using coordinate analysis and parabolic approximation for the mass flow balance principle, the strip velocities eliminating the use of forward slips and backward slips were calculated. In order to reduce the effect of roll eccentricity on the tension measurement, a filter based on bilinear transformation was de- signed. Applying a first-order Taylor series approximation, the transfer function matrix model of interstand tension stress was derived. The actual measurements on-site and the final calculation results showed that the established model had high calculation accuracy and was beneficial for interstand tension control of random cold rolling process.展开更多
Based on classical density functional theory, an expression of the pressure tensor for inhomogeneous fluids is presented. This takes into account greater correlation between particles, especially for systems that are ...Based on classical density functional theory, an expression of the pressure tensor for inhomogeneous fluids is presented. This takes into account greater correlation between particles, especially for systems that are geometrically confined or involve an interface. The density and pressure components of Lennard-Jones fluids confined in hard and softened nano-cavities are calculated. A comparison between the results of this work and IK expression suggests that the agreement depends on temperature. The interracial tension for hard sphere fluids agrees well with the Monte Carlo result when the bulk density is not too large. The results of the solid fluid interracial tension for Lennard-Jones fluids demonstrate that different types of external potentials modulate the interfacial tension in different manners.展开更多
This paper presents a study on the motion response of a tension-leg platform(TLP) under first-and second-order wave forces, including the mean-drift force, difference and sum-frequency forces. The second-order wave fo...This paper presents a study on the motion response of a tension-leg platform(TLP) under first-and second-order wave forces, including the mean-drift force, difference and sum-frequency forces. The second-order wave force is calculated using the full-field quadratic transfer function(QTF). The coupled effect of the horizontal motions, such as surge, sway and yaw motions, and the set-down motion are taken into consideration by the nonlinear restoring matrix. The time-domain analysis with 50-yr random sea state is performed. A comparison of the results of different case studies is made to assess the influence of second-order wave force on the motions of the platform. The analysis shows that the second-order wave force has a major impact on motions of the TLP. The second-order difference-frequency wave force has an obvious influence on the low-frequency motions of surge and sway, and also will induce a large set-down motion which is an important part of heave motion. Besides, the second-order sum-frequency force will induce a set of high-frequency motions of roll and pitch. However, little influence of second-order wave force is found on the yaw motion.展开更多
文摘A new form function involving parameters Pi is presented. On the basis of the form function, an initial form of tension structure was Sound by interpolating through the control points on boundary of the structure. The form function can be controlled by changing beta (1) according to the pre-tension and the boundary of the structure. The final form of a tension structure should be an equilibrium system under the pretension. To examine the nature of the initial form, the FEM was used. Many examples show that the initial form gives a very ideal result for equal or unequal pre-tension in two directions of the structure. In general cases, there is little difference between the initial form and the final one.
文摘In this paper,such a new lateral displacement function is proposed that the lateral flow velocity is con- tinuous at the entry and the exit of deformation zone.A new kind of finite strip method—the third power B-spline finite strip method—is put forward to simulate strip rolling process.Front and back tension stresses are formulated.The computed results of the transverse distributions of the front and back tension stresses are close to the experimental results.The paper lays a foundation for further analysing the three-dimensional stresses and deformations of strip rolling.
文摘In this paper the results of a high-speed tension experiment of the SiC_w/Al composite have been reported and a simplified theoretical model has been developed to study the fracture mechanism of composites in high-speed tension. This theoretical model provides a new explanation for the increase of dynamic fracture strength of composites in high-speed tension.
文摘Background: Children are affected by disorders that have an impact on the respiratory muscles. Inspiratory muscle function can be assessed by means of the noninvasive tension–time index of the inspiratory muscles(TTImus). Our objectives were to identify the determinants of TTImus in healthy children and to report normal values of TTImus in this population.Methods: We measured weight, height, upper arm muscle area(UAMA), and TTImusin 96 children aged 6–18 years. The level and frequency of aerobic activity was assessed by questionnaire.Results: TTImuswas significantly lower in male subjects(0.095 ± 0.038, mean ± SD) compared with female subjects(0.126 ± 0.056)(p = 0.002).TTImus was significantly lower in regularly exercising(0.093 ± 0.040) compared with nonexercising subjects(0.130 ± 0.053)(p < 0.001). TTImus was significantly negatively related to age(r =-0.239, p = 0.019), weight(r =-0.214, p = 0.037), height(r =-0.355, p < 0.001), and UAMA(r =-0.222, p = 0.030). Multivariate logistic regression analysis revealed that height and aerobic exercise were significantly related to TTImus independently of age, weight, and UAMA. The predictive regression equation for TTImus in male subjects was TTImus = 0.228-0.001 × height(cm), and in female subjects it was TTImus = 0.320-0.001 × height(cm).Conclusion: Gender, age, anthropometry, skeletal muscularity, and aerobic exercise are significantly associated with indices of inspiratory muscle function in children. Normal values of TTImus in healthy children are reported.
文摘In this paper a method has been proposed for the calculation of cohesive work and thus sur-face tension of liquids by the Monte Carlo computer simulation method with the use of Kihara po-tential. The surface tension values calculated for liquid argon, oxygen and nitrogen are in fairagreement with the experimental data.
基金the support by the National Natural Science Foundation of China(Nos.51709247 and 51490675)the National Key R&D Program of China(No.2016YFE0200100)
文摘The statistical and distribution characteristics of the responses of a floater and its mooring lines are essential in designing floating/mooring systems.In general,the dynamic responses of offshore structures obey a Gaussian distribution,assuming that the structural system,and sea loads are linear or weakly nonlinear.However,mooring systems and wave loads are considerably nonlinear,and the dynamic responses of hull/mooring systems are non-Gaussian.In this study,the dynamic responses of two types of floaters,semi-submersible and spar platforms,and their mooring lines are computed using coupled dynamic analysis in the time domain.Herein,the statistical characteristics and distributions of the hull motion and mooring line tension are discussed and compared.The statistical distributions of the dynamic responses have strong non-Gaussianity and are unreasonably fitted by a Gaussian distribution for the two floating and mooring systems.Then,the effects of water depth,wave parameters,and low-frequency and wave-frequency components on the non-Gaussianity of the hull motion,and mooring line tension are investigated and discussed.A comparison of the statistical distributions of the responses with various probability density functions,including the Gamma,Gaussian,General Extreme Value,Weibull,and Gaussian Mixture Model(GMM)distributions,shows that the GMM distribution is better than the others for characterizing the statistical distributions of the hull motion,and mooring line tension responses.Furthermore,the GMM distribution has the best accuracy of response prediction.
基金Item Sponsored by Fundamental Research Funds for the Central Universities of China(N110307001)
文摘The interstand tension control is one of the most important ways to meet tight tolerances for strip product quality during tandem cold rolling process. Using coordinate analysis and parabolic approximation for the mass flow balance principle, the strip velocities eliminating the use of forward slips and backward slips were calculated. In order to reduce the effect of roll eccentricity on the tension measurement, a filter based on bilinear transformation was de- signed. Applying a first-order Taylor series approximation, the transfer function matrix model of interstand tension stress was derived. The actual measurements on-site and the final calculation results showed that the established model had high calculation accuracy and was beneficial for interstand tension control of random cold rolling process.
基金Project supported by the North China Electric Power University Campus Foundation (Grant No. 200911036)
文摘Based on classical density functional theory, an expression of the pressure tensor for inhomogeneous fluids is presented. This takes into account greater correlation between particles, especially for systems that are geometrically confined or involve an interface. The density and pressure components of Lennard-Jones fluids confined in hard and softened nano-cavities are calculated. A comparison between the results of this work and IK expression suggests that the agreement depends on temperature. The interracial tension for hard sphere fluids agrees well with the Monte Carlo result when the bulk density is not too large. The results of the solid fluid interracial tension for Lennard-Jones fluids demonstrate that different types of external potentials modulate the interfacial tension in different manners.
基金supported by the National Natural Science Foundation of China(Nos.51239008 and 51279130)
文摘This paper presents a study on the motion response of a tension-leg platform(TLP) under first-and second-order wave forces, including the mean-drift force, difference and sum-frequency forces. The second-order wave force is calculated using the full-field quadratic transfer function(QTF). The coupled effect of the horizontal motions, such as surge, sway and yaw motions, and the set-down motion are taken into consideration by the nonlinear restoring matrix. The time-domain analysis with 50-yr random sea state is performed. A comparison of the results of different case studies is made to assess the influence of second-order wave force on the motions of the platform. The analysis shows that the second-order wave force has a major impact on motions of the TLP. The second-order difference-frequency wave force has an obvious influence on the low-frequency motions of surge and sway, and also will induce a large set-down motion which is an important part of heave motion. Besides, the second-order sum-frequency force will induce a set of high-frequency motions of roll and pitch. However, little influence of second-order wave force is found on the yaw motion.
