Study on the Horizontal Distribution Law of Flood Water and Sediment Factors under the Effect of Vegetation on a Curved Beach

The sediment-laden floodplain flood is affected by beach vegetation and the shape of curved compound channels. The laws of water and sediment exchange and deposition distribution in beach troughs are very complex and play a significant role in the formation and development of secondary suspended rivers, the adjustment of beach horizontal gradients, and even the evolution of flood control situations. This study used a combination of experimental simulations and theoretical research to carry out a generalized model test of floodplain flood evolution, analyzing the transverse distribution characteristics of sediment-laden flow and sediment factors in a curved compound channel under the conditions of beach vegetation, proposing a theoretical model of transverse distribution of velocity and sediment concentration that is based on the momentum equation considering the inertial force of the lateral secondary flow and river curvature. The results showed the following: (1) The model test results for floodplain flood in the compound channel with curved vegetation showed that the main stream was not only concentrated in the main channel but also appeared near the foot of the left and right bank levees and formed flood discharge along the embankment, as the beach siltation was mainly concentrated in the beach lip; (2) The arrangement of full vegetation on the beach had a uniform effect on the velocity distribution of the beach, which can reduce the phenomenon of excessive velocity at the foot of the beach and increase the velocity effect in the main channel; and (3) Through five numerical examples, the lateral velocity distribution model of a curved compound channel with beach vegetation was tested and, in general, the analysis model was consistent with the experimental results. The research results will provide a theoretical basis for river management and have great significance for enriching the basic theory of water and sediment movement and promoting the integration of hydraulics, river dynamics, and ecology.

FLAT CIRCULAR SOLENOID BETWEEN MASSIVE BIFILAR COILS. ANALYSIS OF ELECTROMAGNETIC PROCESSES

An analysis and numerical estimates of induction effects in the metal of a flat circular solenoid located between the branches of an external bifilar coil in a flat inductor system excited by unidirectional currents in the bifilar windings are presented. Such a device, the design of which was first proposed earlier by the authors of this work, is of practical interest for circuits of equipment for magnetic-pulse processing of metals. The use of the considered inductor system makes it possible to minimize the influence of induction effects on electromagnetic processes in the metal of the internal inductor. Numerical estimates are obtained for the induced currents excited in the metal of the inner circular inductor placed between the outer windings of the bifilar coil. It is shown that in the low-frequency mode of acting fields, the time dependence of the excited current is a derivative of the time dependence of the exciting current and the transverse distribution of the current in the metal of the internal inductor is a linear dependence passing through the central axis of the inductor. In the high-frequency regime of acting fields, the time dependence and the radial distribution of the excited current coincide with the corresponding analogs for the exciting current, and the transverse distribution of the induced current is characteristic of a sharp surface effect, when the induced current is displaced to the boundary surfaces of the metal. It is proved that the minimum influence of the fields of the external bifilar on the electromagnetic processes in the internal inductor should be observed in the low-frequency mode, when the spatial superposition of multidirectional induced currents adds up to the zero value of the excited electromotive force of induction. The results of the analysis based on the specific calculations performed are aimed at finding the conditions for the successful technical implementation of the proposed inductor system. The creation of workable models of the proposed inductor systems and experiments to determine the real conditions for their maximum efficiency are seen as very promising in the direction of subsequent research.

Transverse Distribution of the Streamwise Velocity for the Open-channel Flow With Floating Vegetated Islands

Floating vegetation islands (FVIs) have been widely utilized in various river ecological restoration projects due to their ability to purify pollutants. FVIs float at the surface of shallow pools with their roots unanchored in the sediment. Biofilm formed by roots under islands filters nutrients and particles in the water flowing through it. Flow field disturbance will occur and transverse distribution of flow velocity will change due to the existence of FVIs. Transport efficiency of suspended solids, nutrients, and pollutants will also be altered. A modified analytical model that considers effects of boundary friction, drag force of vegetation, transverse shear turbulence, and secondary flow is established to predict transverse variation of depth-averaged streamwise velocity for the open-channel flow with FVIs using Shiono and Knight method. The simulation results with suitable boundary conditions successfully predicted lateral profile of the depth-averaged streamwise velocity compared with the experimental results of symmetrical and unsymmetrical arrangements of FVIs. Hence, the presented model can provide guidance for investigating flow characteristics of rivers with FVIs.

Study on the Method of Moving Load Identification Based on Strain Influence Line

In order to improve the accuracy of load identification and study the influence of transverse distribution, a novel method was proposed for the moving load identification based on strain influence line and the load transverse distribution under consideration. The load identification theory based on strain influence line was derived, and the strain integral coefficient was proposed for the identification. A series of numerical simulations and experiments were carried out to verify the method. The numerical results showed that the method without considering the load transverse distribution was not suitable for solving the space problem, and the method with the load transverse distribution under consideration has a high identification accuracy and excellent anti-noise performance. The experimental results showed that the speed identification error was smaller than ±5%, and the vehicle speed had no obvious influence on the identification results of the vehicle weight. Moreover, the average identification error of the vehicle weight was smaller than ±10%, and the error of more than 90% of samples was smaller than ±5%.

ELECTROMAGNETIC PROCESSES IN A SYSTEM WITH A PLANE CIRCULAR SOLENOID BETWEEN MASSIVE BIFILARY COILS

Purpose. Currently, in order to save materials and energy costs, devices have been developed using inductor systems with bifilar coils used in equipment for magnetic-pulse processing of metals. The purpose of this work is to obtain design relations based on a rigorous solution of the edge electrodynamics for the analysis of electromagnetic processes in a real metal of a circular solenoid of finite thickness placed between massive multi-turn coils of a bifilar with unidirectional currents in a flat inductor system. Methodology. To solve this problem, Maxwell’s equations with appropriate boundary conditions and Laplace transforms were used. Results. Based on the exact solution of the boundary value problem, the space-time function of the density of the induced current, which arises in a flat solenoid when the system is excited by harmonic unidirectional currents in massive bifilar windings, is obtained. On the basis of numerical calculations, it was found that in the low-frequency mode, the transverse distribution of the induced current is linear, symmetric about the central axis of the inductor. In the high-frequency mode, the transverse distribution of the induced current is characteristic of the case of a sharp surface effect. The conditions for the minimum influence of the fields of the external bifilar on the processes in the internal inductor are revealed. Originality. The novelty of this work lies in proposing the idea of the design of the inductor system, as well as in the exact solution of the electrodynamics problem and obtaining the calculated expressions for the analysis of electromagnetic processes. Practical value. On the basis of the obtained formulas and the performed calculations, the efficiency of the proposed calculation model has been proved, which makes it possible to use it as a basic model for similar inductor systems in determining the real conditions of their maximum efficiency. Figures 2, references 17.

Finding a suitable fit function used to determine the Physical width of the Flux tube with Dynamical fermions

We have determined the width of the flux tube for several temperatures and distances using four different fit functions in order to determine the appropriate function that fits the data of the middle transverse distribution of flux tube with the dynamical fermions. Our results have revealed that only one fitting function cannot determine the width of the flux tube at the given temperatures and distances. We conclude that appropriate fit functions are a four coefficient function where R < 0.8 fm and where Gaussian function is R > 0.8 fm.