coupling

摘要： The past decade has witnessed the substantial growth in research interests and progress on the subject of coupled hydro-mechanical processes in rocks and soils,driven mainly by the surge of research in unconventional hydrocarbon reservoirs and associated hazards.Many coupling techniques have been developed to include the effects of fluid flow in the discrete element method(DEM),and the techniques have been applied to a variety of geomechanical problems.Although these coupling methods have been successfully applied in various engineering fields,no single fluid/DEM coupling method is universal due to the complexity of engineering problems and the limitations of the numerical methods.For researchers and engineers,the key to solve a specific problem is to select the most appropriate fluid/DEM coupling method among these modeling technologies.The purpose of this paper is to give a comprehensive review of fluid flow/DEM coupling methods and relevant research.Given their importance,the availability or unavailability of best practice guidelines is outlined.The theoretical background and current status of DEM are introduced first,and the principles,applications,and advantages and disadvantages of different fluid flow/DEM coupling methods are discussed.Finally,a summary with speculation on future development trends is given.

摘要： An adjustable bed is a supporting structure designed to provide a seating base or platform, for a 5.0 KW micro steam turbine generator plant prior to its mounting on a block-type concrete foundation. The design of the bed frame and flanges was carried out by considering the predetermined weights of the turbine and generator (alternator) [1]. On this basis, steel materials of U-channels and angle irons were used in the fabrication of the generator bed. The bed was designed to be adjustable by accommodating direct coupling of the turbine with the generator, and the belt drive. Fabrication was carried out by welding, machining, and assembly. During assembly, the bed was made to accommodate damping materials in order to reduce the vibration of the plant [2]. The performance of the unit with or without vibration isolator when they are axially connected with flexible flange coupling or transversely connected with sets of belt and pulley, in succession respectively. The results showed that a reduction in the force transmitted to the supporting structure occurred when the vibration produced by the unit is isolated from its base by the use of a vibration isolator, maximum reduction of 99.95% achieved when axially coupled and 99.91% when transversely connected with belt and pulley system [3].

摘要： In this paper,the authors propose a method of three-dimensional(3D)magnetotelluric(MT)forward modeling algorithm based on the meshfree and finite element coupling method.The model is discretized by regular nodes in the central area,and the radial point interpolation method(RPIM)based on the global weakness is utilized to construct the meshfree shape function.The Governing equations in each background gird are solved by Gaussian integration.In the extended area where the points are sparsely distributed,to avoid the instability of the meshfree method,finite element method(FEM)with regular grids is used to solve the governing equation.Finally,the meshfree and finite element governing equations are coupled by the continuity of the field at the interfaces,and the direct solution technique is used to realize the 3D MT forward modeling.Numerical experiments of several typical electrical models are used to verify the effectiveness of the method.

摘要： [Objectives]The paper was to study the effect of droplet drift on spray quality of plant protection UAV.[Methods]Based on the theory of multiphase flow and the method of particle kinematics,the force and motion trajectory of droplet sprayed by plant protection UAV were theoretically analyzed and mathematically modeled.On the basis of the assumption of wind speed in the ground layer and the laminar sublayer,that is,it is assumed that the wind speed in the area of wind measurement was approximately a linear distribution,the coupling iterative solution of the equations was carried out.The influence of droplet diameter,flight height,flight speed of plant protection UAV,course angle,wind speed,wind direction,initial droplet velocity and direction of initial velocity on droplet drift were analyzed.The influence of the coupling effect of each factor on droplet drift was further discussed and the distribution of droplet drift concentration was obtained.[Results]The wind speed and direction had much influence on the drift distance of droplets,and the drift distance and the initial velocity angle show a quadratic function distribution.Under the given conditions,the drift distance was the closest when the initial velocity angle was about 20°.The droplet drift was mainly distributed scatteredly around the nozzle.[Conclusions]The study provides a reference for improving the spraying quality of plant protection UAV.

摘要： In the process of radar data acquisition,limited amount of information can be provided to post-processing interpretation by the data acquisition method of single-input and single-output,however,the location and physical parameter information of geological body can be obtained more accurately by using Multi-Input Multi-Output(MIMO)antenna with multiple transmitters and multiple receivers.Especially when collecting borehole radar data and the aperture is very narrow,but the antenna is required to be able to ensure better results in a larger frequency band,therefore,the size of the antenna will be greatly challenged.Meanwhile,the close arrangement of multiple transmitting and receiving antennas will inevitably affect the signal radiation.Based on the borehole radar,this paper simulates and optimizes the Single-Input Multi-Output antenna(SIMO antenna),the size of which meets the aperture requirements,using HFSS antenna simulation software,and explores the factors affecting the antenna return loss and isolation.Among them,the radius of the dipole has little effect on the return loss and isolation,whereas increasing the number of receiving antennas or increasing the transceiver distance will significantly affect the antenna coupling,with a significant reduction in the amplitude of isolation.

摘要： The lattice of the Shanghai Synchrotron Radiation Facility(SSRF) storage ring was upgraded in the Phase-II beamline project, and thus far, 18 insertion devices(IDs) have been installed. The IDs cause closed-orbit distortions, tune drift, and coupling distortions in the SSRF storage ring, all of which are significant issues that require solutions. In this study, an ID orbit feedforward compensation system based on a response matrix using corrector coils was developed, and it was applied to all commissioned IDs in the SSRF storage ring. After correction, the maximum ID-induced horizontal and vertical orbit distortions were less than 5.0 and 3.5 μm, respectively. Some interesting phenomena observed during the measurement process were explained. Additionally, optical and coupling feedforward systems were developed using quadrupole and skew quadrupole magnets installed on the front and back of elliptically polarizing undulators(EPUs). Moreover, over nearly four months of operation, the developed strategy delivered a satisfactory performance in the SSRF storage ring.

摘要： The interactions of electromagnetic waves with the human body are complex and depend on several factors related to the characteristics of the incident wave, including its frequency, its intensity, the polarization of the tissue encountered, the geometry of the tissue and its electromagnetic properties. That’s to say, the dielectric permittivity, the conductivity and the type of coupling between the field and the exposed body. A biological system irradiated by an electromagnetic wave is traversed by induced currents of non-negligible density;the water molecules present in the biological tissues exposed to the electromagnetic field will begin to oscillate at the frequency of the incident wave, thus creating internal friction responsible for the heating of the irradiated tissues. This heating will be all the more important as the tissues are rich in water. This article presents the establishment from a mathematical and numerical analysis explaining the phenomena of interaction and consequences between electromagnetic waves and health. Since the total electric field in the biological system is unknown, that is why it can be determined by the Finite Difference Time Domain FDTD method to assess the electromagnetic power distribution in the biological system under study. For this purpose, the detailed on the mechanisms of interaction of microwave electromagnetic waves with the human body have been presented. Mathematical analysis using Maxwell’s equations as well as bio-heat equations is the basis of this study for a consistent result. Therefore, a thermal model of biological tissues based on an electrical analogy has been developed. By the principle of duality, an electrical model in the dielectric form of a multilayered human tissue was used in order to obtain a corresponding thermal model. This thermal model made it possible to evaluate the temperature profile of biological tissues during exposure to electromagnetic waves. The simulation results obtained from computer tools show that the temperature in the biological tissue is a linear function of the duration of exposure to microwave electromagnetic waves.

摘要： This study aimed to investigate the characteristics of the coupling of the center of pressure (COP) movement and toes in older adults during one-legged standing (OLS). Participants were community dwelling older and younger adults. Toe vertical force during the OLS was recorded using a plantar-pressure distribution system, and the vertical forces in the hallux, little toe, and the first and fifth metatarsophalangeal (MP) joints were analyzed. A cross-correlation function was performed to examine the coordination between toes and between COP movement and four regions of the foot. The cross-correlation functions showed no significant difference in coefficients between toes. The OLS duration in the older adults was significantly correlated with the coefficient between the medial-lateral component of the COP and the first MP region. This study suggests that it is important to press the first MP region appropriately relative to COP movement to maintain the OLS.

摘要： Structure-performance relationship is a complex issue in iron-catalyzed Fischer-Tropsch synthesis,and it is not easy to elucidate it by experimental investigations.First-principle calculation is a powerful method for explaining experimental results and guiding catalyst design.In this study,we investigated the reaction mechanisms of CH_(4)formation and C-C coupling on fourχ-Fe_(5)C_(2)surfaces and established the kinetic equations to compare the rates of CH_(4)formation and C_(1)+C_(1)coupling reactions and determine the CH_(4)/C_(2+)selectivity.The results show that the geometry of theχ-Fe_(5)C_(2)surfaces has little effect on the formation rate of CH_(4);however,the C_(1)+C_(1)coupling reactions are significantly affected by the surface geometry.The C_(1)+C_(1)coupling reaction rates on the terraced-like(510)and(021)surfaces are much higher than those on the stepped-like(001)and(100)surfaces.Based on these results,we established a Brùnsted-Evans-Polanyi(BEP)relationship between the effective barrier difference for CH_(4)formation and C_(1)+C_(1)coupling(ΔE_(eff))and the adsorption energy of C+4H(ΔE_(C+4H))onχ-Fe_(5)C_(2)surfaces.ΔE_(C+4H)can be used as a descriptor for CH_(4)/C_(2+)selectivity on different surfaces ofχ-Fe_(5)C_(2).

摘要： In this paper,based upon the characteristics of elastic modal combination of large solid bundled launch vehicles,the finite element theory is used to describe the complex elastic vibration of a solid bundled launch vehicle,and a new three-channel unified elastic vibration equation was established.The elastic vibration equation can reflect the coupling between channels and between boosters and core stage.Some issues need consideration in the theoretical derivation,an engineering application was proposed,and the elastic vibration model was verified.The results of the theoretical derivation and simulation show that the elastic vibration equation of a solid bundled launch vehicle established in the paper is correct and can meet the needs for the engineering application.

摘要： 缩短辅助加工时间，降低劳动强度，提高劳动生产率来降低生产成本是机械加工中面临的主要问题，而生产中夹具的设计是实现这一目标的关键。本文通过对coupling和连接件的传统钻加工方法存在的问题进行分析与探讨，提出了钻孔工序的孔夹具设计，此夹具投入使用后缩短了加工时间，降低了劳动强度，提高了加工效率，取得了显著的经济效益和社会效益。

摘要： 本实用新型公开了一种粉末冶金Coupling自动整形工艺生产线，其方法是将Coupling批量无规则放入振动料仓内，通过振动进入振动盘，通过振动盘的振动，使得Coupling沿着特殊设计的多阶滑道进行方向一致性的排列，并前进到直线振动导轨内，通过直线导轨的振动，Coupling进行前移，并排列一致落入专用落料工装内，通过一个联动的接料装置，Couplig进入整形转盘的夹具内，转盘回转至整形压机模具位置时，产品被压入精确设计尺寸的模具内，随后再托出，从而获得高精度的产品，并最终通过转盘带动和压料气缸实现落料，整个生产过程无需人工操作，全部为生产线自动完成连续生产。生产线具有自动化程度高，生产效率高，模具可以实现标准化，换型费用低，节能环保等特点。