Search results

This research aims to focus on developing a customized support surface using additive manufacturing (AM) for effective pressure relief for patients who are in bed or wheelchair suffering from pressure ulcers (PU).

A novel customized support surface is developed using AM technology incorporated with magnetic levitation and ball and socket mechanisms. Magnetic levitation provides cushioning effect for the developed cushion to users who are sitting in a wheelchair and increases the rate of healing. The ball and socket mechanism provides the user body's self-adaptive mechanism and reduces shear and friction forces between the surfaces of the additive manufactured cushion and the human buttocks.

From the results of ISO 16480-6 biomechanical standardized tests, the additive manufactured support surface performed better than, or on par with, the most widely available commercial cushions. It is evident that the developed cushion’s peak pressure values are lower when compared with other cushions. The overall efficiency of the developed cushion was qualitatively reported; 67% of people felt it was excellent and 22% of people responded as good and 11% were satisfactory. Henceforth, the overall effectiveness of the developed support surface provides a better experience to the end-user in the view of PU reduction.

A developed additive manufactured customized support surface will be an alternative approach for the reduction of PU, and it overcomes the drawbacks faced by the currently available cushions.

The purpose of this paper is to introduce a novel cross (+) type yoke with hybrid electromagnets and new reluctance modeling to precisely calculate attraction force is given.

The comparison of attraction force and torque analyses between the proposed formulation and the existing formulation in the literature is comparatively presented. For the correctness of the force and torque values calculated in the model created, the system was created in ANSYS Maxwell and its accuracy was proved by making analyses. The maglev carrier system is inherently unstable from the point of view of control engineering. For that, it needs an active controller to eliminate this instability. For the levitation of the carrier system, it is necessary to design a controller in three axes (z, α and β). I-PD controller was designed for the air gap control of the carrier system in three axes and the controller parameters were determined by the canonical method.

While the new formulation proposed in the modeling of the carrier system has a maximum error of 1.03%, the existing formula in the literature has an error of 16.83% in the levitation distance point.

A novel cross-type hybrid carrier system has been proposed in the literature. With the double integral used in modeling the system, it takes a long time to solve symbolically, and it is difficult to simulate dynamic behavior in control validation. To solve this problem, attraction force and inclination torque values are easily characterized by new formulation and besides the simulations are conducted easily. The experimental setup was manufactured and assembled, and the carrier system was successfully levitated, and reference tracking was performed without overshoot.

Permanent magnet passive magnetic bearings (PMBs) are used for suspension of rotating shafts in one direction. PMBs with alternating radially magnetized rings having back iron is one of the most optimum configurations among all configurations of PMBs. This paper aims to investigate the effect of the conductivity and permeability of these back irons on the stiffness and damping of the configuration.

The stiffness and damping of the configuration will be calculated through a 2D dynamic analytical method and validated by FEM simulations.

The results of the paper show how the permeability and conductivity of the back irons can affect stiffness and damping of PMB. Furthermore, the size of the magnets and the air intervals between them are optimized for maximum stiffness and damping.

The results show that these bearings can have some intrinsic damping without any loss of stiffness, which can be useful for many applications.

The purpose of this paper is to present the use of artificial immune systems (AISs) to solve constrained design optimization problems for active magnetic bearings (AMBs).

This research applies the AIS approach, more specifically, a representative clonal selection-based AIS called CLONALG, to the single-objective structural design optimization of AMBs. In addition, when compared with a genetic algorithm (GA) developed in the previous work, the CLONALG fails to produce best solutions when a nearly zero feasible ratio occurs in an AMB design problem. Therefore, an AIS called ARISCO (AIS for constrained optimization) is proposed to address the above issue.

A total of six AMB design cases are solved by the GA, CLONALG, and ARISCO. Based on the simulation results, in terms of solution quality, the ARISCO is shown to have better overall performance than the CLONALG and GA. In particular, when solving a problem with a nearly zero feasible ratio, the ARISCO and GA perform equally and both outperform the CLONALG.

In summary, the contributions of this paper include: this research applies the AIS approach, more precisely, the CLONALG, to the single-objective structural design optimization of AMBs; the ARISCO overall produces better AMB designs than the CLONALG and a GA developed in the previous work; in situations where a nearly zero feasible ratio occurs, the ARISCO and GA perform equally, and they both outperform the CLONALG.

A conveyor device is studied with the aim to reduce the friction between the inner surface of the beam and the chain. The lower is the friction between the chain and the beam, the lower is the surface wear. The magnetic repulsion force among permanent magnets (PMs) placed on the beam and on the chain is utilized to reduce friction. The paper aims to discuss these issues.

The considered magnetic suspension is realized with PMs in repulsive configuration; it is designed by solving a constrained optimization problem, with reference to the geometry of the 90° horizontal bend FlexLink WL322 conveyor. Flux density field and its gradient are evaluated using volume integral equation method, allowing to calculate the forces acting on the chain and the stiffness of the magnetic suspension.

The magnetic suspension prototype was manufactured and tested. The experimental and calculated values of the forces acting on the chain compares well. A stable horizontal equilibrium of the chain was obtained during both static and dynamical tests.

The quasi-static model used neglects the dynamical interactions among the elements of the chain, the PMs and loads weight during motions and the eddy current losses in the aluminium beam. However the dynamical tests on the prototype show that the chain motion is regular up to the nominal velocity all along the conveyor with the exception of the trailing edge of the 90° curve.

The tests on the prototype show the possibility of a removal or at least a reduction of the friction force between the chain and the inner side of the beam by means of a passive magnetic suspension. As a consequence a reduction of noise and vibrations and an increase of the mean-time-to-failure is expected.

Prototype testing shows that the unavoidable vertical instability of the magnetic forces has no practical consequence since, reducing the allowed vertical gap, the chain is stabilized by the gravitational force.

The purpose of this paper is to analyze the characteristics of the factors influencing the effect of magnetic levitation, including the impedance angle of the levitated coil, number of turns, material parameter, frequency of excitation and geometric parameters. The final purpose is to provide approaches to increasing the levitation effect.

Some design principles and strategies for levitation systems are suggested, such as selecting the number of turns of the levitated coil, choosing the frequency of excitation considering the saturation phenomenon of levitation force against frequency and deciding the section area of the excitation coil and its ratio of height and thickness.

The magnetic force is not always repulsive in a cycle. Therefore, the key approach to increasing the levitation is to increase the period when the force is repulsive and decrease the time when attractive. The impedance angle of the equivalent circuit of the levitated coil determines the ratio of the two periods, and the larger the angle, the longer the repulsion period. A valuable finding is that a saturation situation exists between the levitation force and frequency; that is, when the frequency increases to a certain value, the increasing degree of force tends to decrease as the frequency increases.

Some influential characteristics were found in some factors against the effect of the levitation system, which is beneficial for improving the efficiency of systems. For example, owing to the saturation phenomenon of the frequency, it is useless to continue increasing the frequency and the copper-levitated coil does not bring much greater force effectiveness than the aluminum coil.

This paper aims to suggest a new revolutionary method and installation for flight on Earth and into outer space.

Methods of electromagnetic physics are used for research and the theory of levitation vehicles is developed and its possibilities researched.

It was found that levitation devices and electricity storage make a jump in aviation, space, storage and transfer energy and many branches of industry.

Many projects were calculated using different versions of the offered AB engine: a small device for levitation‐flight of a human (including flight from Earth to outer space), fly VTOL car (track), big VTOL aircraft, suspended low‐altitude stationary satellite, powerful Space Shuttle‐like booster for travel to the Moon and Mars without spending energy (spent energy is replenished in braking when the ship returns from another planet to its point of origin), using AB‐devices in military, in sea‐going ships (submarines), in energy industry (for example, as small storage of electric energy) and so on. The vehicles equipped with AB propulsion can take flight for days and cover distances of 10,000s of kilometers at hypersonic or extra‐atmosphere space speeds.

The paper promises a new revolutionary method of flight on Earth and into outer space.

The paper seeks to present an algorithm for a dynamical field‐circuit coupled simulation of an electromagnetic linear actuator operating in automated control systems.

The mathematical model includes: a transient electromagnetic field formulation for a non‐linear conducting and moving medium, equations which describe the electric circuits of the converter and the supply system, the equation of mechanical motion, the equation describing closed‐loop control and models for the sensor and the PID controller. The numerical implementation is based on the finite element method and the step‐by‐step algorithm for time discretization. In order to account for the nonlinearity of the ferromagnetic core the Newton‐Raphson procedure has been applied. The influence of the PID controller settings on the operation of the controlled actuator is shown. Dynamic disturbances, e.g. step change of the set value of mover position or change of loading force, have been analyzed.

The elaborated algorithm and the computer code can be an effective tool for field‐circuit simulation of the dynamics of an electromagnetic linear actuator operating in an automatic control system. Only tapered plunger should be used as multi‐stable actuators.

The study provides information of value in electromagnetic research.

Introduces the fourth and final chapter of the ISEF 1999 Proceedings by stating electric and magnetic fields are influenced, in a reciprocal way, by thermal and mechanical fields. Looks at the coupling of fields in a device or a system as a prescribed effect. Points out that there are 12 contributions included ‐ covering magnetic levitation or induction heating, superconducting devices and possible effects to the human body due to electric impressed fields.

The purpose of this paper is to present an algorithm of the optimization of the dynamic parameters of an electromagnetic linear actuator operating in error‐actuated control system.

The elaborated “unaided” software consists of two main parts: optimization solver and numerical model of the actuator. Genetic algorithm has been used for optimization. The coupled field‐circuit‐mechanical model for the simulation of the system dynamics has been applied. Different optimization problems have been considered. The shape of the steady‐state force‐displacement actuator characteristic has been imposed and its deviation has been minimised. Next, the total operation time of the actuator without feedback, and the setup time of the actuator with feedback are minimised. Finally, required trajectory of movement has been imposed and trajectory error is minimised.

The elaborated algorithm and the computer code can be an effective tool for field‐circuit simulation of the dynamics of an electromagnetic linear actuator that operates in an automatic control system. It enables optimal design of the electromechanical system in respect to its dynamic properties.

The elaborated algorithm and the computer code presented in this paper can be an effective tool for the field‐circuit simulation of the dynamics of an electromagnetic linear actuator that operates in an automation control system.