The Experts below are selected from a list of 10356 Experts worldwide ranked by ideXlab platform
Boguang Zhen - One of the best experts on this subject based on the ideXlab platform.
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designing cancer immunotherapy trials with random treatment time Lag Effect
Statistics in Medicine, 2018Co-Authors: Zhenzhen Xu, Yongsoek Park, Boguang ZhenAbstract:: In some clinical settings such as the cancer immunotherapy trials, a treatment time-Lag Effect may be present and the Lag duration possibly vary from subject to subject. An efficient study design and analysis procedure should not only take into account the time-Lag Effect but also consider the individual heterogeneity in the Lag duration. In this paper, we present a Generalized Piecewise Weighted Logrank (GPW-Logrank) test, designed to account for the random time-Lag Effect while maximizing the study power with respect to the weights. Based on the proposed test, both analytic and numeric approaches are developed for the sample size and power calculation. Asymptotic properties are derived and finite sample efficiency is evaluated in simulations. Compared with the standard practice ignoring the delayed Effect, the proposed design and analysis procedures are substantially more efficient when a random Lag is expected; further, compared with the existing methods by Xu et al considering the fixed time-Lag Effect, the proposed approaches are significantly more robust when the Lag model is misspecified. An R package (DelayedEffect.Design) is developed for implementation.
Zhang Yuan-hai - One of the best experts on this subject based on the ideXlab platform.
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Finite Element Analysis of Shear Lag Effect of Skew Box Girder Bridges
Journal of Southwest Jiaotong University, 2020Co-Authors: Zhang Yuan-hai, Li QiaoAbstract:The generalized conforming element for thin plate bending and the membrane element for plane stress were combined to obtain a plane shell element to analyze the shear Lag Effect for continuous skew box girder bridges. Comparison between experimental and computed results proved the Effectiveness of this analytical method in the three-dimensional analysis of skew box girder bridges. As an example, skew box girders with different degrees of skew were analyzed respectively to investigate longitudinal and transversal distributions of shear Lag Effect under concentrated or uniform force, and were compared with the corresponding right box girders. The result shows that a skew box girder has more remarkable shear Lag behavior than a right box girder. Shear Lag Effect must be fully considered in the design of a skew box girder.
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Analysis of Shear Lag Effect of Single Box and Twin-cell Skew Box Girder
Journal of Lanzhou Jiaotong University, 2020Co-Authors: Zhang Yuan-haiAbstract:The SHELL63 unit of ANSYS program was used to analyze the longitudinal and transversal distributions of shear Lag Effect for single box twin-cell three-span continuous skew box girder with different degrees of skew under concentrated or uniform force.The results show that the distributions of shear Lag Effect of the cross-section Ⅱ-Ⅱ of skew box girder were affected by the skew angle greatly,and the negative shear Lag Effect was appeared under both the force.When skew continuous box girder were analyzed respectively to investigate longitudinal distributions of shear Lag Effect,there was a kind of phenomenon of negative shear Lag Effect,and the division position of the positive and negative distributions of shear Lag Effect was a quarter of the span length from the cross-section Ⅰ-Ⅰ of skew continuous box girder.A box girder was very different from an orthogonal box girder in the shear Lag behavior,and the shear Lag Effect must be fully considered in the design of a skew box girder.
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Analysis of Shear Lag Effect on Thin-walled Box Girder
Journal of Lanzhou Jiaotong University, 2020Co-Authors: Zhang Yuan-haiAbstract:On the basis of the energy variation principle,the fundamental differential equations and boundary conditions concerning w(x) and U(x) are established.Based on the differential equations,the formulas for deflection of box girders with shear Lag Effect are derived for both simply supported and cantilever box girders under uniform or concentrated loads.The maximum deflections under various circumstances are analyzed.It is shown that the maximum deflection of thin-walled box girder considering shear Lag Effect is apparently larger than that of the elementary beam theory.The deflection increase of simply supported box girder is more remarkable than that of cantilever box girder.
Zhenzhen Xu - One of the best experts on this subject based on the ideXlab platform.
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designing cancer immunotherapy trials with random treatment time Lag Effect
Statistics in Medicine, 2018Co-Authors: Zhenzhen Xu, Yongsoek Park, Boguang ZhenAbstract:: In some clinical settings such as the cancer immunotherapy trials, a treatment time-Lag Effect may be present and the Lag duration possibly vary from subject to subject. An efficient study design and analysis procedure should not only take into account the time-Lag Effect but also consider the individual heterogeneity in the Lag duration. In this paper, we present a Generalized Piecewise Weighted Logrank (GPW-Logrank) test, designed to account for the random time-Lag Effect while maximizing the study power with respect to the weights. Based on the proposed test, both analytic and numeric approaches are developed for the sample size and power calculation. Asymptotic properties are derived and finite sample efficiency is evaluated in simulations. Compared with the standard practice ignoring the delayed Effect, the proposed design and analysis procedures are substantially more efficient when a random Lag is expected; further, compared with the existing methods by Xu et al considering the fixed time-Lag Effect, the proposed approaches are significantly more robust when the Lag model is misspecified. An R package (DelayedEffect.Design) is developed for implementation.
Yongsoek Park - One of the best experts on this subject based on the ideXlab platform.
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designing cancer immunotherapy trials with random treatment time Lag Effect
Statistics in Medicine, 2018Co-Authors: Zhenzhen Xu, Yongsoek Park, Boguang ZhenAbstract:: In some clinical settings such as the cancer immunotherapy trials, a treatment time-Lag Effect may be present and the Lag duration possibly vary from subject to subject. An efficient study design and analysis procedure should not only take into account the time-Lag Effect but also consider the individual heterogeneity in the Lag duration. In this paper, we present a Generalized Piecewise Weighted Logrank (GPW-Logrank) test, designed to account for the random time-Lag Effect while maximizing the study power with respect to the weights. Based on the proposed test, both analytic and numeric approaches are developed for the sample size and power calculation. Asymptotic properties are derived and finite sample efficiency is evaluated in simulations. Compared with the standard practice ignoring the delayed Effect, the proposed design and analysis procedures are substantially more efficient when a random Lag is expected; further, compared with the existing methods by Xu et al considering the fixed time-Lag Effect, the proposed approaches are significantly more robust when the Lag model is misspecified. An R package (DelayedEffect.Design) is developed for implementation.
Bing Li - One of the best experts on this subject based on the ideXlab platform.
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Shear Lag Effect in steel-concrete composite beam in hogging moment
Steel and Composite Structures, 2020Co-Authors: Zhongwen Zhang, Bing LiAbstract:Shear Lag Effect can be an important phenomenon to consider in design of the steel-concrete composite beams. Researchers have found that the Effect can be strongly related with the moment distribution, the stiffness and the ductility of the composite beams. For continuous composite beams expected to sustain hogging moment, the shear Lag Effect can be more distinct as cracking of the concrete slab reduces its shear stiffness. Despite its influences on behaviour of the steel-concrete composite beams, a method for calculating the shear Lag Effect in steel-concrete composite beams sustaining hogging moment is still not available. Shear Lag Effect in steel-concrete composite beams sustaining hogging moment is investigated in this paper. A method was proposed specifically for predicting the Effect in the cracked part of the steel-concrete composite beam. The method is validated against available experimental data. At last, FE studies are conducted for steel-concrete composite beams with different design parameters, loading conditions and boundary conditions to further investigate the shear Lag Effect and compare with the proposed method.
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shear Lag Effect in tension flange of rc walls with flanged sections
Engineering Structures, 2017Co-Authors: Zhongwen Zhang, Bing LiAbstract:Abstract A new method for considering the shear Lag Effect in the flange of reinforced concrete (RC) walls with flanged sections is proposed. The method is developed based on the truss analogy for the cracked flange segment in tension. Comparisons with the experimental data reveal that the proposed method can predict the influence of the shear Lag Effect in the tested RC structural walls with flanged sections with greater accuracy as compared to the conventional method of Effective flange width. Furthermore, parametric studies were performed based on nonlinear finite element models for further investigation of the shear Lag Effect and accuracy of the proposed method. The parametric studies show that the influences of the height and the length of the wall and the distribution of longitudinal reinforcement were reasonably captured by the proposed method when the maximum tensile strain in the flange was close to the yielding strain of the longitudinal reinforcing bars.
