Vertical rotation effect on turbulence characteristics in an open channel flow

This paper solves the three-dimensional Navier-Stokes equation by a fractional-step method with the Reynolds number Reτ=194 and the rotation number Nτ=0-0.12. When Nτ is less than 0.06, the turbulence statistics relevant to the spanwise velocity fluctuation are enhanced, but other statistics are suppressed. When Nτ is larger than 0.06, all the turbulence statistics decrease significantly. Reynolds stress budgets elucidate that turbulence kinetic energy in the vertical direction is transferred into the streamwise and spanwise directions. The flow structures exhibit that the bursting processes near the bottom wall are ejected toward the free surface. Evident change of near-surface streak structures of the velocity fluctuations are revealed.

Comparison and Selection of Arch-Rib Construction Schemes for Continuous Beam arch Composite Bridge of High Speed Railway

The paper summarizes the four different construction schemes based on engineering cases for the arch rib construction of continuous beam-arch composite bridges for high-speed railways.These methods include in-situ assembly,segmental lifting,incremental launching and longitudinal moving,and vertical rotation.The temporary structural designs,process methods,and technological equipment for each construction scheme are described in detail.The advantages and disadvantages of each scheme and its application scope under various conditions are analyzed,and opinions and suggestions for guiding the application of each scheme are proposed.The comparison and selection analyses show that the four arch rib construction schemes have certain applicability under different conditions such as bridge site status,bridge span,and construction environment.With the continuous increase of bridge span and progress of construction technological equipment,the arch rib construction technology is developing towards the overall erection direction.This leads to more obvious technical advantages of the segmental lifting method,incremental launching and longitudinal moving method,and vertical rotation method.Therefore,it is necessary to select the best construction scheme according to the construction status and technical conditions during application.

Three-dimensional mixed convection squeezing flow

The unsteady mixed convection squeezing flow of an incompressible Newtonian fluid between two vertical parallel planes is discussed. The fluid is electrically conducting. The governing equations are transformed into ordinary differential equations （ODEs） by appropriate transformations. The transformed equations are solved successfully by a modern and powerful technique. The effects of the emerging parameters on the flow and heat transfer characteristics are studied and examined. The values of the skin friction coefficient and the local Nusselt number are tabulated and analyzed.

State-of-the-art review of the development and application of bridge rotation construction methods in China

This work provides a comprehensive review of the development and applications of bridge rotation construction methods(BRMs) and related critical construction technologies in China. A brief history of BRMs and an outline of their categories,including the rotating structural system, are given first. Subsequently, a discussion on the recent practice of BRMs in China is carried out from three types of bridges:(1) continuous beam and rigid frame bridges;(2) arch bridges;(3) cable-stayed bridges.For each group, a survey of the vital bridge cases that have adopted BRMs in China in the past two decades is provided. Key parameters, including the structure weight of rotation, maximum cantilever span, and rotation duration, are also compared and discussed. Afterward, the principles and applications of the weighing test and the spherical hinge stability, which are both related to the safety of the horizontal rotation construction process, are analyzed in the paper. Additionally, the limitations of BRMs are presented and discussed, and the article concludes with a summary of the current use and future trend of BRMs. The information and experience of BRMs provided in this work can be referenced by engineers and researchers who are devoted to the construction of bridges.