Gate Motion Research Articles

Research on the influence of rigid body modes on the operating vibration of arc gate

Abstract The 5# arc working gate of Jiangshan Wanyao Reservoir is composed of the suspension system of the gate and the steel wire rope, which has a serious vibration phenomenon when running without water. Firstly, the rigid body modal analysis of the gate suspension system is analyzed, the position size of key components such as gate support hinge shaft, gate motion guide embedded parts, and main beam position state is measured and evaluated on site, and the dynamic stress and vibration of the support arm are tested and analyzed during gate operation. It is concluded that the influence rule and weight of the steel wire rope on the rigid body mode of the gate, the torsional position of the gate, and the uneven operation condition of the side guide lead to the rigid body mode of the gate. It is suggested to improve the twisting state of the gate, adjust the unevenness of the embedded parts, and weaken the factors that induce the modal vibration of the rigid body.

DESAIN DAN ANALISIS MEKANISME BENDUNG GERAK DENGAN RADIAL GATE UNTUK PENANGANAN BANJIR ROB

<p>Tidal floods are high tides that occur excessively on the mainland. Radial gate weir<br />is a door building that moves around in a cylindrical shape to regulate the water<br />level elevation. This study aims to determine the influence factor of the radial gate<br />movement weir mechanism, analyze the fluid mechanics of the radial gate during<br />tidal flooding. This research is experimental design research, namely, making a<br />prototype design of the radial gate motion weir mechanism and analysis of<br />parameter data in the form of hydrostatic pressure, hydrodynamic pressure, critical<br />flow, and sub critical flow. The conclusion of this study is, the design is planned to<br />work when: the automation system runs because the two proximity sensors touch the<br />30 cm water level, activate the linear actuator to close the radial gate, the water<br />pump turns on and 15 cm opens the radial gate, the water pump stops. The results of<br />parameter data analysis: hydrostatic pressure of water level 30 cm = 32.0 N/m2,<br />hydrodynamic pressure due to earthquake according to (DSI) in Cilacap = 0.1211<br />tf/m2, BMKG SIG (III/Light)= 33,600 tf/m2, (IV/ Medium)= 96.075 tf/m2,<br />(V/Weight)= 148.3125 tf/m2. Critical flow rate of water level is 15 cm = 0.0149<br />m3/second, sub-critical flow rate is 0.0098 m3/second.</p>

Numerical simulations of air-water flow and rigid-body motion based on two-liquid CLSVOF/IB method and overset mesh

For simulating air-water flows with rigid-body motion, the rigid boundary has to be body-fitted and discretized in the traditional dynamic mesh method, which will lead to a severe computational instability due to the mesh deformations when large displacements are involved. A two-liquid CLSVOF/IB (coupled Level Set and Volume of Fluid/Immersed Boundary method) method for directional numerical simulation of air-water flow and water-water mixing with a moving rigid-body is presented in this study, which is based on overset mesh method. In order to make the CLSVOF method applicable to two different cell sizes in overset mesh and background mesh respectively, the formula of the artificial time step size in the re-initialization equation of Level Set (LS) method is improved. A simple and effective IB method suitable for the overset mesh method and the dynamic mesh technique is also implemented. The IB method marks the cells around the rigid-body as forcing cells in the overset mesh, and then an artificial momentum forcing term is introduced into the momentum equation of the fluid to satisfy no-slip boundary condition in fluid-solid interface. The method has been validated with laboratory data, including two-liquid dam-break flow with wet bed and single-liquid water entry problem. The effects of various parameters such as ambient water depth and gate motion on mixing pattern and front propagation of water-water interface are investigated in the dam-break flow problems. The results have good agreement with the published experimental results and emphasize the necessity of considering the gate in numerical simulation of dam-break flow. In the numerical simulation of a free-falling rigid-body impacting the free surface of water, the simulation results, including the computed shape of the air cavity and displacement of free-falling rigid-body, agree well with experimental results.

Holding Force and Vertical Vibration of Emergency Gate in the Closing Process: Physical and Numerical Modelling

A two-dimensional unsteady fluid–structure interaction numerical model was established, based on the physical model test, to investigate the influence of vertical vibration on the holding force of an emergency gate in the closing process. Gate motion was controlled by the user-defined function in Fluent. Attention was paid to the relationship between the vertical vibration, hydrodynamic loads and flow discharge. The experiment results show that holding force has three typical forms in the closing process and it is related to the service gate height. The numerical model can reflect the gate vertical vibration and the gate-closing displacement in the form of steps. Gate vertical vibration in the closing process is a motion-induced vibration caused by gate active falling. Moreover, the transition from full-flow to open-flow behind the emergency gate has a great influence on the gate vertical vibration. With a small gate opening, gate vertical vibration makes the flow discharge fluctuation increase. Furthermore, flow discharge has an influence on the gate body loads, which is mainly concentrated in the upstream plate and gate bottom. Finally, the lift force coefficient at the gate bottom is different from the standard and is mainly controlled by the outflow boundary condition. The simulation result is in good agreement with the experiment and the relative error meets engineering requirements, suggesting that the numerical model can successfully simulate the gate fluid–structure interaction and reproduce the characteristics of physical quantities in the closing process.

Voltage-Sensing Mechanism of Neuronal KCNQ Channels

The voltage-gated potassium channel KCNQ2/KCNQ3 (KCNQ2/3) mediates the M-current (IKM) in neurons. The IKM channel contributes to maintaining the resting membrane potential and impedes repetitive neuronal firing, therefore playing a crucial role in controlling neuronal excitability. Mutations within the voltage-sensor (S4) of the IKM channel have been linked to Benign Familial Neonatal Seizures (BFNS) and epileptic encephalopathies, conditions that currently affect 50 million people worldwide. However, how KCNQ2/3 channels function remains largely unknown. Here, we use two-electrode voltage clamp and inside-out patch clamp in a Xenopus oocyte expression system to assess external and internal accessibility of S4 cysteine-substituted residues to the membrane-impermeable thiol reagent (MTSET) in homomeric and heteromeric KCNQ channels. We find that in homomeric KCNQ2 (and in KCNQ3) channels, extracellular MTSET labels residues N190C (Q218C) with a similar time course in both closed and open states. By contrast, extracellular MTSET modifies residues A193 to R201 in KCNQ2 (G219-S228 in KCNQ3) at depolarized potentials, but not at hyperpolarized potentials, suggesting that these residues likely lie buried in the membrane in the closed state. We also use voltage clamp fluorometry (VCF) to determine S4 movement in KCNQ2/3 channels. In homomeric KCNQ channels, the time course and voltage dependence of fluorescence F(V) and ionic current G(V) correlate, as if the S4 and the gate motion were directly coupled. Moreover, in KCNQ2, the F(V) follows the voltage dependence of the modification rate of residue A193C. Our data also indicate that the presence of KCNQ3 subunits affects the S4 and gate of KCNQ2 in heteromeric KCNQ2/3 channels.

Meshfree modeling of near field two-liquid mixing process in the presence of different obstacles

In this research two-liquid dam break induced mixing process in the presence of different obstacles was modeled using δ-SPH method. Water and polyetilenoxid (PEO) were used as two different Newtonian fluids. The model was validated using laboratory data, including single-liquid dam break over wet bed and over triangular and rectangular obstacles as well as two-liquid dam break. Then, the effect of various parameters such as ambient water depth and gate motion characteristics on mixing pattern and front propagation of water-PEO interface were investigated. The results show the necessity of considering the gate in numerical simulation. Furthermore, a two-step formula for gate motion consisting accelerated phase and a uniform velocity phase was used leading to increasing the accuracy of the results. Finally, the flow simulation was performed to evaluate and compare the mixing pattern, front propagation of water-PEO solution interface as well as maximum flow height in the presence of three different obstacles.

Experimental study of the interaction of dambreak with a vertical cylinder

The aim of this research has been to conduct experimental measurements of the dam break impact on a vertical cylinder placed over a dry horizontal bed. The work aims to emphasize the effect of cylinder cross-section on the nature of impact as well as provide accurate and comprehensive data for the validation of computational fluid dynamics(CFD) codes. The experimental setup is based on a series of experiments conducted in the Research Institute for Applied Mechanics (RIAM) between the years 2010 and 2017. The gate motion is thoroughly studied and a novel gate motion formula is proposed based on the recent experimental data. The effect of gate obstruction on the time of impact with the cylindrical obstacle is presented and correlated to the parameters of the proposed motion profile thus emphasizing its significance in the numerical modeling of dam break flow. The effect of the cross-section of the cylinder is studied by examining the pressure signal on the cylinder as well as the vertical wall downstream of the cylinder. The pressure on the wall is compared with the no-obstacle case to highlight its effect on the pressure of the downstream conditions. The square cylinder is found to experience fairly similar pressure impulse as the circular cylinder. However, the square cylinder seems to impede the flow momentum in the x-direction more than the circular case. The data-set presented in this article is provided as Supplementary Materials including gate motion measurement, pressure measurements, and high-resolution videos.

Challenges and implemented technologies used in autonomous drone racing

Autonomous drone racing (ADR) is a challenge for autonomous drones to navigate a cluttered indoor environment without relying on any external sensing in which all the sensing and computing must be done with onboard resources. Although no team could complete the whole racing track so far, most successful teams implemented waypoint tracking methods and robust visual recognition of the gates of distinct colors because the complete environmental information was given to participants before the events. In this paper, we introduce the purpose of ADR as a benchmark testing ground for autonomous drone technologies and analyze challenges and technologies used in the two previous ADRs held in IROS 2016 and IROS 2017. Five teams which participated in these events present their implemented technologies that cover modified ORB-SLAM, robust alignment method for waypoints deployment, sensor fusion for motion estimation, deep learning for gate detection and motion control, and stereo-vision for gate detection.

Finite Element and Smoothed Particle Hydrodynamics Modeling of Fluid–Structure Interaction Using a Unified Computational Methodology

This study illustrates a comparison of two numerical methods under a unified computational platform for solving fluid–structure interaction (FSI) problems. The first is an arbitrary Lagrangian–Eulerian (ALE)-based fluid model coupled to a structural finite element (FE) method (ALE-FE/FE), and the second is a smoothed particle hydrodynamics (SPH) method coupled to the same structural FE code (SPH/FE). The predictive capabilities and computational efficiency of both the numerical methods are evaluated and validated against a canonical problem of a rapidly varying flow past an elastic gate for which experimental data are available. In both numerical solutions, the fluid flow is governed by the Navier–Stokes equation, and the elastic gate is modeled as a flexible structure. Numerical simulation results show that the ALE-FE/FE continuum approach not only captures the dynamic behavior properly but also predicts the water-free surface profiles and the elastic gate deformations accurately. On the other hand, the coupled purely Lagrangian approach of the SPH/FE under an identical computational platform is found to be less accurate and efficient in predicting the dynamics of the elastic gate motion and the water-free surface profiles.

Numerical investigation of the gate motion effect on a dam break flow

The effects of a moving gate on dam break flow experiments are numerically considered in this paper. The dam break flow process is modelled by a sudden gate release. A Constrained Interpolation Profile (CIP)-based model is employed to solve the Navier-Stokes equations with the free surface boundary condition to deal with the water-air-gate interactions. In addition, the VOF-type THINC/SW method is used to capture the free surface. The movable gate is simulated by an immersed boundary, and a gate motion formula is proposed from existing experimental data and applied in the dam break flow computations. The difference between the water profile and pressure domain with/without gate motion is examined. The dam breaks with different gate motions are discussed as well. The numerical results show that the proposed gate motion formula correlates well with the numerical modelling, and the gate motion has a significant influence in the water collapse process and cannot be neglected in the study of dam break.

Flap gate farm: From Venice lagoon defense to resonating wave energy production. Part 2: Synchronous response to incident waves in open sea

We consider a flap gate farm, i.e. a series of P arrays, each made of Q neighbouring flap gates, in an open sea of constant depth, forced by monochromatic incident waves. The effect of the gate thickness on the dynamics of the system is taken into account. By means of Green's theorem a system of hypersingular integral equations for the velocity potential in the fluid domain is solved in terms of Legendre polynomials. We show that synchronous excitation of the natural frequencies of Sammarco et al. (2013) yields large amplitude response of gate motion. This aspect is fundamental for the optimisation of the gate farm for energy production.

Modeling the Dosimetric Effects of Repainting in Respiratory-Gated Spot Scanning Proton Treatment Plans

Interplay between target motion and spot scanning proton delivery can lead to significant degradation in plan quality. The combination of repainting and respiratory gating was investigated as a strategy to mitigate these effects. An analytic routine modeled three-dimensional dose distributions of pencil-beam proton plans delivered to a moving target. Spot positions and weights were established for a single field to deliver 100 cGy to a static, 15-cm deep, 3-cm radius spherical CTV with a 1-cm isotropic ITV expansion. The interplay effect was studied in subsequent calculations by modeling proton delivery from a clinical synchrotron based spot scanning system and respiratory target motion, patterned from surrogate breathing traces from clinical 4DCT scans and normalized to nominal 1 cm amplitude. Motion both parallel and orthogonal to the raster direction of the beam was investigated. Repainting was modeled by setting a maximum MU to be delivered in each visit of the beam to a spot. The beam rastered over all prescribed spots in an energy layer, either delivering the prescribed MU or the maximum allowed MU. The beam rescanned over any spots in that layer with remaining MU until the prescribed MU was reached for all spots; then the system switched to the next energy level. This method of repainting is supported by our commercial planning system and does not require rapid energy changes. For each of 13 patient breathing traces, the dose from 20 distinct delivery schemes was computed. These consisted of all combinations of four gate window amplitudes (no gate, 0.75 cm, 0.5 cm, 0.3 cm) and five repainting techniques with varying maximum MU. Delivery strategies were inter-compared based on target coverage, dose homogeneity, and delivery time. Notable degradation and variability in plan quality were observed for ungated delivery. Decreasing the gate window reduced this variability and improved plan quality at the expense of longer delivery time. The following table summarizes the delivery time benefit obtained when adding maximum-MU repainting while simultaneously preserving plan quality. Maximum-MU repainting helps suppress the interplay effect from intra-gate motion, with only a modest penalty in delivery time. The magnitude of this improvement is strongly influenced by individual patient breathing patterns.Scientific Abstract 3796; TableComparison of target homogeneity and delivery time for various gating and repainting techniquesStatic TargetMotion, No Gate (Parallel/Orthogonal)Motion, Small Gate (Parallel/Orthogonal)Motion, Medium Gate w/ Repainting (Parallel/Orthogonal)Target Homogeneity(D5-D95)[%]2.510.5/23.45.2/11.96.2/12.2Delivery Time (s)103103169126 Open table in a new tab

NUMERICAL MODEL FOR FLAP-GATE RESPONSE TO TSUNAMI AND ITS VERIFICATION BY HYDRAULIC EXPERIMENTS

A flap-gate breakwater is a new type structure for coastal disaster reduction against tsunamis and storm surges. The breakwater usually lies down on the seabed and rises up as a seawall with its buoyancy when tsunami or storm surge occurs. In our previous experimental studies, wave blocking capabilities of the flap-gate against tsunamis were confirmed, and the characteristics of the gate motion and wave pressure have been clarified changing wave condition. Present study develops a numerical model considering fluid-body interactions for the flap-gate and validation of the numerical model is conducted. The numerical model consists of combining the overset grid method and level set method for solving both flap-gate motions and free surface water motions accurately. It is shown that the developed numerical model gives accurate predictions of flap-gate motions against hydraulic model experiments.

A Laterally Movable Gate Field Effect Transistor

A laterally movable gate field effect transistor (LMGFET) device that directly couples lateral mechanical gate motion to drain current of a FET is presented in this paper. Lateral motion of the FET gate results in a change in channel width, keeping the channel length and the gap between the gate and the oxide layer constant. This results in a change in channel current that, in principle, is linearly proportional to mechanical motion. The operating principle of an LMGFET, along with details of the fabrication process for a depletion-type LMGFET device, is described. Fabricated LMGFET shows an average drain current sensitivity to gate motion of -5.8 ¿A/¿m at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> = 20 V and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> = 0 V for 60-¿m gate motion. A model for the fabricated LMGFET is developed based on electrical measurements. The device shows promise both as a sensor and as an actuator in MEMS and other related applications.

EXPERIMENTAL STUDY ON RESPONSE CHARACTERISTICS OF FLAP GATE BREAKWATER AGAINST WAVES

A flap gate breakwater is a new type structure for coastal disaster reduction; the breakwater usually lies down on a seabed and rises up through sea surface with buoyancy when tsunami or storm surge occurs. In past studies, it has been confirmed that the flap gate breakwater has capabilities against tsunamis. The characteristics of wave pressure acting on flap gate are different from those on a fixed gate and a breakwater since the flap gate moves according to acting waves or tsunamis. The present study examined the characteristics of wave pressure acting on the flap gate by hydraulic experiments using monochromatic waves and tsunamis. It was confirmed that the gate motion and wave pressure were closely related, and wave pressure was reduced by employing fluid resistance plates.

Bistatic SAR Processing and Experiments

Bistatic synthetic aperture radar (SAR) uses a separated transmitter and receiver flying on different platforms to achieve benefits like exploitation of additional information contained in the bistatic reflectivity of targets, reduced vulnerability for military applications, forward-looking SAR imaging, or increased radar cross section. Besides technical problems such as synchronization of the oscillators, involved adjustment of transmit pulse versus receive gate timing, antenna pointing, flight coordination, and motion compensation, the development of a bistatic focusing algorithm is still in progress and not sufficiently solved. As a step to a numerically efficient processor, this paper presents a bistatic range migration algorithm for the translationally invariant case, where transmitter and receiver have equal velocity vectors. In this paper, the algorithm was successfully applied to simulated and real bistatic data. The real bistatic data have been acquired with the Forschungsgesellschaft fur Angewandte Naturwissenschaften (FGAN)'s X-band SAR systems, namely the Airborne Experimental Radar II and the Phased Array Multifunctional Imaging Radar, in October 2003

運動学的考察による下肢筋疲労に及ぼすテーピングの影響に関する研究(下肢)

In this paper, the effect of the kinesio taping on the muscle fatigue of the lower extremity is investigated. To this end, a subject performs usual gate motion after load motion using the muscle force measuring and training machine. Some characteristic quantities from the kinematical sense during gate motion are measured and compared between the cases with and without taping. As a result, in the case of gate motion, it was shown that the muscle fatigue in the case of gate motion with taping is less than the one without taping. The load of gate motion is, however, little, so that it was noted that the lower extremity may exert more power to resist the taping. The other hand, in the case of load motion, no significant differences of the characteristic quantities can be observed between the cases with and without taping. It was considered that the taping has not much effect on muscle fatigue in the case of load motion.

721 下端放水を行うシェル形長径間ゲートの流体関連振動に関する研究 : 自励振動特性に及ぼす傾斜面の水平距離の影響

This paper presents effects of the horizontal length of the weir plate for flow-induced vibration of shell-type long-span gates with small underflow. Experimental results for flow-induced vibration of 5 model gates, which have different length of the weir plate, were shown first and the instability for each gate was described secondly. Furthermore the relationship between the instability and gate motion trajectory derived using experimental results for the hydrodynamic force acting on their inclined weir plate were discussed.

Dynamic Performance Evaluation of Gate Vibration

This paper demonstrates how the use of appropriately scaled model experiments can effectively be used to evaluate the dynamic performance of a new gate system. The physical scale models studied in this investigation are exact replicas of the innovative hydraulically actuated wickets to be placed at the Olmsted Locks and Dam for controlling water flow and maintaining a navigable pool on the lower Ohio River. Operating shapes of the flow-induced gate motion at critical configurations are compared with the wet characteristic modes of the wicket to determine the potential resonant vibration problem. These wet modes are extracted such that the effects of structural and hydraulic boundary conditions of the flow field are accounted for in the modal experiment. Experimental results indicate that random energy contents of an ambient excitation can readily be used to estimate the physical characteristic modes of a wet structure. The study also shows that operational deflected shapes for potentially alarming excitations can be compared with such wet natural modes to identify resonance problems. This evaluation procedure demonstrates the convenience in using ambient vibration for the detection of self-excitation problems during the service life of the system.

Stochastic gating influence on the kinetics of diffusion-limited reactions

We study how the kinetics of diffusion-influenced reactions is modified when the reactivity of species fluctuates in time (stochastically gated) with emphasis on the many-particle aspect of the problem. Because of the fact that the dynamics of ligand binding to proteins originally motivated the problem, it is considered in that context. Recently, Zhou and Szabo [J. Phys. Chem. 100, 2597 (1996)] have demonstrated many-particle effects in the problem and found that the kinetics of reaction between a gated protein with a large number of ligands significantly differs from that between a protein and gated ligands. With our approach, the difference between the kinetics of ligand-gated and protein-gated reactions appears formally the same as the difference between the target and trapping problems despite the origin of the corresponding effects and their manifestations are distinctly different. A simple approximate method to treat the many-particle effects is proposed. The theory is applied to a particular two-state gating model. Explicit analytical expressions for the protein survival probability are obtained. We show that (1) for ligand-gated reactions, gating is effectively accounted for by the appropriate reduction of the species reactivity and (2) for protein-gated reactions, the survival probability changes its time behavior from exponential (fast gating) to nonexponential (slow gating). The role of intensity and asymmetry of the gate motion is discussed.