Suspension Force Research Articles

Microscopic Mechanism and Percolation Model of Dynamic Deposition of Elemental Sulfur Particles in Acidic Gas Reservoirs.

The dissolution of elemental sulfur in acidic gas leads to its precipitation as gas pressure decreases, thereby causing potential damage to the formation due to the deposition of sulfur particles. Previous sulfur deposition prediction models often relied on the solubility of sulfur in acidic gas and the stress state of sulfur particles to determine the occurrence of deposition, thus establishing predictive models. However, in the presence of complex geological conditions, the multiphase flow through porous media and the adsorption of particles on pore throat walls can also influence sulfur particle deposition to some degree. It is well known that sulfur particle deposition during gas reservoir development exhibits instability, with multiple factors influencing the deposited sulfur particles. Particularly noteworthy is the influence of airflow velocity, which can resuspend sulfur particles that are physically adsorbed on pore throat surfaces, thereby reintegrating them into the gas phase. Additionally, the dynamic deposition of larger sulfur particles involves a dynamic process. This study elucidates the dynamic process of sulfur deposition by considering the diverse transport dynamics of sulfur particles. Physical adsorption and desorption behaviors of sulfur particles are determined based on variations in reservoir conditions. The desorption status of sulfur particles with different particle sizes within the formation is established by evaluating the equilibrium between the force exerted on the pore throat wall and the suspension force generated by gas flow. The critical conditions for sulfur deposition in Yuanba gas reservoir were obtained by substituting on-site parameters into calculations. Moreover, a mathematical model is proposed to describe the dynamic deposition and migration of sulfur particles, adopting principles from continuous porous media porous flow theory, fluid flow mass conservation, as well as sulfur particle desorption and migration. The formulated model is solved, and its resulting solution process and outcomes hold significant implications for numerical simulation and predictive assessment of the development impact on gas reservoirs, particularly in later stages.

A Ground-Based Electrostatically Suspended Accelerometer.

In this study, we have developed an electrostatically suspended accelerometer (ESA) specifically designed for ground use. To ensure sufficient overload capacity and minimize noise resulting from high suspension voltage, we introduced a proof mass design featuring a hollow, thin-walled cylinder with a thin flange fixed at the center, offering the highest surface-area-to-mass ratio compared to various typical proof mass structures. Preload voltage is directly applied to the proof mass via a golden wire, effectively reducing the maximum supply voltage for suspension. The arrangement of suspension electrodes, offering five degrees of freedom and minimizing cross-talk, was designed to prioritize simplicity and maximize the utilization of electrode area for suspension purposes. The displacement detection and electrostatic suspension force were accurately modeled based on the structure. A controller incorporating an inverse winding mechanism was developed and simulated using Simulink. The simulation results unequivocally demonstrate the successful completion of the stable initial levitation process and suspension under ±1g overload.

Design and Analysis of Low-Gravity Simulation Scheme for Mars Ascent Vehicle

The sample carried back by the Mars Ascent Vehicle (MAV) is a potential flagship mission of deep space exploration in recent years. A low-gravity simulation experiment is an effective method and a necessary stage for verifying the performance of the MAV launch dynamic in Earth’s gravity. In this paper, the uniqueness of low-gravity simulation is illustrated by the classical pulley balance method for the high dynamic process of a test model of the MAV. Its movement direction is the same as the compensation force, which leads to the relaxation of the sling and the failure of the compensation force in traditional cable suspension. Here, three cable suspension schemes including an improved pulley balancing scheme based on a coordinate transformation scheme and based on a dynamic pulley group scheme are proposed. For the actual launch condition of the MAV, the motion state of the ascent under the schemes and the real Mars launch are compared, which proves the feasibility of the schemes. Among them, the improved pulley balancing scheme has the best gravity compensation effect, and the error between the average value and the required value is the smallest, only 1%.

Investigation of design methodology for doubly-fed bearingless flux reversal motor

This article integrates the technology of bearingless motors with the basic theory of magnetic flux reverse motors, proposes a doubly fed bearingless magnetic flux reverse motor, and conducts research on its structural design, operating mechanism, electromagnetic performance analysis, mathematical model, control method, digital control system, and other aspects. The basic structure of a new type of doubly fed bearingless magnetic flux reverse motor is designed, and the principle of radial suspension force generation is studied. The performance related to torque and radial suspension force is analyzed. A mathematical model of torque and radial suspension force is established, including magnetic field distribution, no-load permanent magnet flux, and no-load back electromotive force. A doubly fed bearingless magnetic flux reverse motor system is designed and constructed, and inductance experiments are conducted.

Torque System Modeling and Electromagnetic Coupling Characteristics Analysis of a Midpoint Injection Type Bearingless Permanent Synchronous Magnet Motor

Taking the Midpoint Injection type Bearingless Permanent Magnet Synchronous Motor (MPI-BL-PMSM) as an object, to solve its problems of large torque pulsation and insufficient suspension force when adopting Midpoint Suspension Current Unilateral Injection (MPSC-UI), a Midpoint Suspension Current Bilateral Injection (MPSC-BI) solution is proposed. Based on the half-winding structure of MPI-BL-PMSM, and from the electromechanical energy conversion principle, the torque model for MPSC-BI solution is established. On this basis, the torque model for MPSC-UI method was derived. The correctness of the established torque mathematical models based on half-winding structure was verified through the finite element method (FEM), and the “dual-frequency” electromagnetic coupling characteristics of suspension current on electromagnetic torque were compared and analyzed from the perspectives of theoretical model and FEM simulation. The results indicate that the MPSC-BI method can effectively suppress or avoid the torque pulsation coupled by suspension current and can obtain about 1-time increase of controllable suspension force; the advantages of MPSC-BI solution in dynamic torque decoupling characteristics are demonstrated, while the only downside is that the coupling effect of torque current on radial suspension force is slightly greater than that of the MPSC-UI method.

Design and harmonic analysis of single winding bearingless PM synchronous motor with high winding coefficient

Compared with double-winding bearingless permanent magnet synchronous motor, single-winding bearingless permanent magnet synchronous motor (SBPMSM) has the advantages of low copper loss and low failure rate. However, if the slot-pole combination of SBPMSM is not reasonably selected, the winding coefficient will be reduced, and even many advantages of the single-winding structure will be offset. In this paper, a single-winding design method based on magnetomotive force (MMF) star diagram is proposed, which can ensure high winding coefficient. The design process of the proposed single winding structure is introduced. This method can match the appropriate number of stator slots according to the number of rotor poles, and the winding phase separation design can be realized by reversing the slot number transposition. The mathematical models of the suspension force and torque of the bearingless permanent magnet synchronous motor are derived considering the magnetic field harmonics, and the 6-slot/2-pole SBPMSM and 18-slot/8-pole SBPMSM are taken as examples to analyze the magnetic field. The finite element simulation models of 6-slot/2-pole SBPMSM and 18-slot/8-pole SBPMSM are built and analyzed. Through the analysis of electromagnetic torque, suspension force and air-gap magnetic field under different magnetic fields, the general rules of main torque fluctuation and suspension force fluctuation are summarized.

Desain Dan Analisa Performa Suspensi Hydraulicpneumatic Suspension System Kendaraan Pertanian Berbasis Mattrack

Indonesia is agrarian country whose people make their living as farmers, but until now still has hard to handle problem using agricultural’s technology, because the development of agricultural’s technology in Indonesia still inadequate, such as crop distribution, because some regions have texture of the ground surface is uneven, with use hydraulicpneumatic suspension and mattrack designed using SOLIDWORK is expected to be able to overcome the distribution of crop yields by adjusting Daihatsu Grandmax PU 1.3 STD. The main of this research is to see response of harmonic oscillatory sinusoidal with amplitude 0.02 m and frequency of 0.5 Hz, response of the damping force and spring force of a hydraulicpneumatic suspension using ideal PID controller. Simulation using MATLAB and Simulink to see continuous results with a time of 20 seconds. The test was carried out on the rear wheels with quarter vehicle systeml, by replacing the conventional suspension with a hydraulicpneumatic which has an orifice diameter of 2 mm and a piston of 78 mm using ASTM D 1298 oil of , for the gas accumulator it has the initial pressure and volume in both cylinders is , of with a floating piston diameter of 78 mm, produces harmonic oscillation movements of the vehicle that are smaller than the road profile conditions, and experience a stable condition at 6.2 seconds. And the maximum oscillating force produced by the mattrack is almost the same as the road profile conditions which produce good road holding.

Design and optimization of H-type asymmetric magnetic suspension vibration absorber for ships

The active–passive hybrid vibration isolation technology emerges with the advancement of the requirements for ship vibration and noise reduction. Among these, the magnetic suspension damper based on magnetic suspension technology has received more attention. In this paper, the effects of magnetic pole area and control current on the magnetic flux density and suspension force are verified by establishing a magnetic suspension structure model and comparing and verifying the results carried out by combining the theoretical formulas and finite element simulation. By exploring the effect of the structure on the magnetic flux density and suspension force, a new H-type asymmetric magnetic suspension structure is proposed and simulated. The results show that the H-type asymmetric magnetic suspension structure is more successful at improving the suspension force while also widening the suspension force response interval and improving the performance of the magnetic suspension damper. In addition to offering a new design concept for the construction of ship vibration and noise reduction structures, this structural solution serves as a reference for the development of magnetic suspension dampers.

Research on Environmental Vibration Induced by High-Speed Maglev Transportation

As a novel form of railway transportation, maglev transportation has the advantages of a better curve negotiation ability and grade ability and lower noise and vibration than traditional urban wheel–rail transportation. Thus, it is suitable for use in urban public transportation. However, the levitation of the widely utilized electromagnet suspension (EMS) system relies on continuously active suspension force adjustment, which gives it vehicle–track-coupled vibration characteristics different to those of the traditional wheel–track transportation system. Despite many research studies focusing on maglev vehicle–track coupling vibration, the environmental vibration influences associated with the running of maglev trains are still unclear. When the vibration propagates to the surroundings beyond certain thresholds, it may lead to various vibration serviceability problems. Practical test results on the environmental vibration induced by maglev transportation are still not enough to generate convincing vibration propagation and attenuation laws. In this research, a series of in situ tests were carried out around the Shanghai maglev line; the results show that the viaduct bridge is helpful in reducing environmental vibration, and an empirical formula was proposed to predict the effect of viaduct column height. Due to the ground wave superposition, a vibration-amplifying zone was also found about 10 m away from the maglev line, in which the vibration magnitude was strong enough to be perceived by the surrounding occupants.

Integrated Control of Torque and Suspension Force Considering Decaying Current of Bearingless Switched Reluctance Motor

Integrated Control of Torque and Suspension Force Considering Decaying Current of Bearingless Switched Reluctance Motor

A sliding mode control of the bearingless permanent magnet slice motor for the blood pump based on the GAPSO

In this paper, we proposed a sliding mode control method for the bearingless permanent magnet slice motor for the blood pump based on the genetic particle swarm algorithm, which aims to solve the problems of strong coupling, strong interference, nonlinearity and uncertainty. Firstly, the mathematical model of rotor torque and suspension force of the bearingless permanent magnet slice motor is established. Secondly, the structure of sliding mode observer is deduced by designing sliding mode surface and control law. And, the performance parameters of sliding mode observer are optimized by the genetic particle swarm optimization algorithm. Thirdly, electromagnetic torque and suspension force control under this control method is studied by Simulink. Finally, the control method is applied to the control of the blood flow of the blood pump, and the rotation speed can effectively control the blood flow. The results indicate that compared with PID control and traditional sliding mode control methods, the sliding mode control method optimized by the genetic particle swarm optimization algorithm greatly improves the control performance of bearingless permanent magnet slice motor. The results show that the blood flow can meet expectations with a small error, which fully meets the blood perfusion requirements of the blood pump.

Design and Optimization of a New Type of Magnetic Suspension Vibration Absorber for Marine Engineering

The magnetic suspension damper, which is based on magnetic suspension technology, is receiving more and more attention from academics as active–passive hybrid damping technology develops. A new symmetric magnetic suspension structure is constructed in this study, and the accuracy of the simulation findings is confirmed by contrasting the output from finite element simulation with the theoretical formulations. On the basis of this, how the structure, size, and material of the electromagnet and armature affect the magnetic flux density, electromagnetic force, and suspension force is investigated. The structure optimization of the electromagnet and armature was performed in accordance with the simulation results, and a new symmetric magnetic suspension structure was produced. The results of the simulation demonstrate that DT4(electrical pure iron) is the ideal material for armatures and electromagnets. The reinforcing ring construction can be built up by the armature to increase suspension force. The suspension force output by the armature will be greatly increased when the size and placement of the reinforcing ring structure are right. The system stiffness adjustment range will expand at this point, enhancing the magnetic suspension damper’s functionality. This study offers novel perspectives for designing structures that reduce vibration and noise in various projects and serves as a guide to constructing magnetic suspension dampers.

Structural stability analysis for a Maglev design

Magnetic levitation train has the advantage of low vibration and noise compared with ordinary railway systems. It also has the potential to become more energy efficient if permanent magnets are properly incorporated. However, suspension forces provided by the magnetic fields may have dynamic instability that needs to be overcome before such design can be utilized. This talk presents a design of permanent magnet group that overcomes the instability of at least one degree of freedom compared with rudimentary levitation configuration. The magnetic forces between components are derived analytically and the system eigen-value problem is presented. It is shown that, in the rudimentary design, unstable modes occur in two degrees of freedom (lateral and rotational), and the new design suppresses one of the two instability modes (rotational). Initial experimental demonstration is also provided.

Public attitudes toward external democracy promotion in Africa

ABSTRACT The proliferation of democratic rule in Africa has been accompanied by external involvement in fostering democracy. The African Union along with various regional organizations have included clauses in their treaties calling for member-state adherence to democratic governance. Moreover, African regional organizations have used punishments such as membership suspension, sanctions, and military force to motivate states experiencing democratic reversals to change course. However, despite these trends, there has been no investigation into how Africans perceive external involvement in fostering democracy. This study remedies this gap by evaluating public attitudes toward such external pressure using the sixth round of the Afrobarometer survey. Specifically, the study explores how individual assessment of electoral practice and a country's and its neighbours' history of unconstitutional changes of government influence approval of external democracy promotion. This article lays the foundation for further investigating the roots of legitimacy of actions taken by international organizations aimed at promoting good governance and democracy.

Decoupling Control of Outer Rotor Coreless Bearingless Permanent Magnet Synchronous Generator Based on Fuzzy Neural Network Inverse System

The outer rotor coreless bearingless permanent magnet synchronous generator is a complex system with multi-variable, nonlinear and strong coupling. So the dynamic decoupling of generation voltage and suspension force is the key to realize stable power generation and reliable operation. In this paper, a decoupling control method based on fuzzy neural network inverse system is proposed. Firstly, the basic structure and working principle of the outer rotor coreless bearingless permanent magnet synchronous generator is introduced in this paper and the mathematical model of the generating voltage and suspension force is established. Then, based on the reversibility analysis of the mathematical model, the inverse system is constructed by using fuzzy neural network. By connecting the inverse system in series with the original system, the original nonlinear system is decoupled into three single-input and single-output linear subsystems. Finally, the designed control system is simulated and experimentally studied. The simulation and experimental results show that this control method can realize decoupling among generation voltage and suspension forces, and the outer rotor coreless bearingless permanent magnet synchronous generator has good dynamic performance and stability.

Analytical Calculation of Hybrid Excitation Transverse Flux Permanent Magnet Synchronous Linear Motor Based on Schwarz–Christoffel Mapping

An analytical calculation method of thrust and suspension force based on Schwarz–Christoffel (SC) mapping is presented for hybrid excitation transverse flux permanent magnet synchronous linear motor (HETFPMSLM) applied to a maglev train. The effectiveness of the analytical calculation is verified by three-dimensional finite element analysis. Firstly, the structure and principle of HETFPMSLM are analyzed, and its longitudinal two-dimensional SC mapping model is proposed. The magnetic field of HETFPMSLM is calculated by MATLAB’s SC Toolbox. Then the suspension force and thrust are calculated by the Maxwell stress tensor method, which is compared with the 3D finite element to verify the accuracy of the analytical calculation.

Toward Reducing Undesired Rotation Torque in Maglev Permanent Magnet Synchronous Linear Motor

The dq current transformation method can be used to achieve the drive control of the maglev permanent magnet synchronous linear motor (MPMSLM). Specifically, the control of the suspension force Fz can be achieved by controlling the d-axis current, and the control of the thrust force Fx can be achieved by controlling the q-axis current. However, the direct use of the dq current transformation method on traditional MPMSLM structures produces an additional rotation torque around the y-axis. In order to reduce this additional torque, a new MPMSLM structure is proposed in this work. First, the characteristics of additional torque through finite element analysis are analyzed. Second, the Halbach permanent magnet array and coil size are optimized, and the topology of the MPMSLM coil is designed to reduce the additional torque. The decoupling performance and current of the proposed MPMSLM are experimentally verified through open-loop experiments using finite element simulation software. Finally, the decoupling algorithm of the generalized inverse matrix is used to achieve the decoupling between forces Fx and Fz and torque Ty and the d-axis and q-axis currents in each drive unit. Based on this, a three-degree-of-freedom closed-loop control system of the MPMSLM is designed. The LabVIEW 2018 software is used for the simulation analysis of the three-degree-of-freedom MPMSLM motion control system, and the results show that the proposed motor structure has superior closed-loop control performance.

Active control for vehicle suspension using a self-powered dual-function active electromagnetic damper

Concerning vehicle suspension techniques, active suspension tends to offer the most precise control performance compared to passive and semi-active alternatives. However, due to its high-power consumption, its practical use is often limited. This study aims to develop an innovative self-powered active suspension by assessing the performance and feasibility of a dual-function active electromagnetic damper (DF-AEMD), which is capable of providing simultaneous force tracking and energy harvesting functions. In addition to outlining its working mechanism, the DF-AEMD is utilized to track the full-loop target control force calculated from the classic linear quadratic regulator in a self-powered manner. From the force tracking standpoint, the DF-AEMD can not only provide damping forces, but also generate actuation forces, and thus achieve better tracking accuracies of target control force and control performances for vehicle suspension than the traditional semi-active damper; while from the energy harvesting aspect, sufficient energy can be harvested simultaneously to realize the self-powered active control. Systematic simulations are conducted to discuss the relationship between control performance and energy harvesting efficiency of the DF-AEMD.

Reduction of Cross-Coupling for Bearingless Doubly Salient Electromagnetic Motor Using Nonsynchronous Rotating Coordinate Transformation

The cross-coupling between the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> -axis suspension forces caused by the salient pole structure leads to unstable suspension control for bearingless doubly salient electromagnetic (BDSEM) motors. In this paper, the cross-coupling characteristics of the 12/8-pole BDSEM motor are analyzed. The inherent orthogonality of the motor structure, as well as of the biased magnetic field, is illustrated. A new control method based on non-synchronous rotating coordinate transformation is proposed. The suspension force characteristics in the proposed non-synchronous rotating frame both under no-load and load conditions are studied by the mathematical model (MM) and finite element (FE) method. A 12/8-pole BDSEM motor and a suspension force controller are developed. The analytical and experimental results show that the suspension force cross-coupling of the BDSEM motor is reduced significantly.

Accurate Modeling and Control System Simulation of Bearingless Brushless DC Motor

Background: Precise modeling and control system design are the basis of highperformance control of dual-winding bearingless brushless DC motors (BL-BLDCM), and the existing research is relatively few. Objective: This paper takes 12-slot/tooth 4-pole BL-BLDCM as the research object, establishes a set of a detailed mathematical model, and designs the control system of BL-BLDCM. Methods: Firstly, the structure of BL-BLDCM and the radial suspension force generation principle were introduced. Secondly, a set of an accurate mathematical model of BL-BLDCM was established which was finally verified by static and dynamic finite element method (FEM), the motor body model and control system were built by Matlab/Simulink software, and the simulation analysis of control performance was completed. Results: The established mathematical model is correct. The BL-BLDCM can generate stable electromagnetic torque and radial magnetic suspension force, and the control system has strong ability of resisting load torque disturbance and radial force load disturbance. Conclusion: It has certain reference significance for the accurate modeling and control system design of later BL-BLDCM.