关于Semigroups of Linear Operators and Applications to Partial Differential Equations的两个注解

基礎講座 電気泳動(Electrophoresis)

This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.

Introduction to the Finite Element Method

The etch rates for 317 combinations of 16 materials (single-crystal silicon, doped, and undoped polysilicon, several types of silicon dioxide, stoichiometric and silicon-rich silicon nitride, aluminum, tungsten, titanium, Ti/W alloy, and two brands of positive photoresist) used in the fabrication of microelectromechanical systems and integrated circuits in 28 wet, plasma, and plasmaless-gas-phase etches (several HF solutions, H/sub 3/PO/sub 4/, HNO/sub 3/+H/sub 2/O+NH/sub 4/F, KOH, Type A aluminum etchant, H/sub 2/O+H/sub 2/O/sub 2/+HF, H/sub 2/O/sub 2/, piranha, acetone, HF vapor, XeF/sub 2/, and various combinations of SF/sub 6/, CF/sub 4/, CHF/sub 3/, Cl/sub 2/, O/sub 2/, N/sub 2/, and He in plasmas) were measured and are tabulated. Etch preparation, use, and chemical reactions (from the technical literature) are given. Sample preparation and MEMS applications are described for the materials.

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Etch rates for micromachining processing

Any device which senses information such as shape, texture, softness, temperature, vibration or shear and normal forces, by physical contact or touch, can be termed a tactile sensor. The importance of tactile sensor technology was recognized in the 1980s, along with a realization of the importance of computers and robotics. Despite this awareness, tactile sensors failed to be strongly adopted in industrial or consumer markets. In this paper, previous expectations of tactile sensors have been reviewed and the reasons for their failure to meet these expectations are discussed. The evolution of different tactile transduction principles, state of art designs and fabrication methods, and their pros and cons, are analyzed. From current development trends, new application areas for tactile sensors have been proposed. Literature from the last few decades has been revisited, and areas which are not appropriate for the use of tactile sensors have been identified. Similarly, the challenges that this technology needs to overcome in order to find its place in the market have been highlighted.

/pdf/a-review-of-tactile-sensing-technologies-with-applications-12ul5smpoy.pdf

A review of tactile sensing technologies with applications in biomedical engineering

Due to their superior performance, high specific power, and flexible operating adaptability, axial piston pumps are widely used in both industrial and mobile applications. In this type of pumps, the pump flow is designed to meets load requirements by the aid of control unit. A pressure transducer senses the load and feeds this information to the control system’s arithmetic unit which computes the required piston stroke to generate the required flow rate. The existing pump’s control system consists of double negative feedback control structure. The inner loop controls the proportional hydraulic valve position; while the outer loop controls the swash plate angle. In order to reduce the pump production cost, simplify its design, and improve its performance; the control system can be redesign and re-constructed to meet the desirable performance. The objective of this paper is to propose a novel single PID controller and investigate the pump overall performance including the hydraulic system smoothness (pipe vibration) and improving its response to load requirement. The results are simulated and then validated experimentally, which show promising results, and the new strategy can be implemented on the axial piston pumps successfully.

Empirical investigation on the influence of bent axial piston pumps' control systems' gains on hydraulic pipes stability

Dynamic Behavior of a Simple Rotor With Dissimilar Hydrodynamic Bearings by Modal Analysis

In capacitive type of micromechatronic systems such as microsensors and microactuators the electrostatic forces prove to have a strong influence on the dynamic behavior of the capacitor plate elements in such systems. Thepresent paper focuses on the analysis of the dynamic behavior of micro plates subjected to both electrostatic field and elastic forces. The Rayleigh - Ritz method is applied to obtain an analytical solution of the problem. The displacement function is conveniently chosen to satisfy the geometrical boundary conditions. The electrostatic and the mechanical energy are expressed in terms of the deflection of the plate. Natural frequencies under dynamic conditions are obtained.

Vibration of Micro Plates in Electrostatic Fields Using Rayleigh-Ritz Method

Active control of whirling vibrations in a deep hole boring bar-workpiece assembly is implemented to improve the surface finish of the drilled piece in BTA (Boring Trepanning Association) deep hole boring process. In the experiment, two proximity pickups and two electrodynamic exciters are used in the Y and Z directions to suppress the whirling motion. The suppression of the whirling motion has been achieved in the absence of cutting loads as well as under cutting conditions while drilling.

Active control of whirling vibrations in boring trepanning association deep hole boring process using two electrodynamic shakers

This paper deals with the robust design of a control system for two planar rigid manipulators required to move the flexible object in the prescribed trajectory while suppressing the vibration of the flexible object. Without approximating or discretizing the beam, the complete system of dynamic equations are derived by combining the manipulator and beam dynamics. The resulting equations have rigid as well as flexible parameters which are coupled together. By using singular perturbation technique, the two subsystems, namely, slow and fast subsystems, are identified. For slow subsystem, a regressor based sliding mode control scheme is developed to track the desired rigid body motion of the object. For fast subsystem, a corresponding feedback control algorithm has been developed to suppress the vibration of the object. Exponential stability results for the closed-loop system with the developed control laws for both slow and fast subsystems are presented. Simulation results demonstrate the versatility of the proposed composite control scheme.

Rama B. Bhat

Papers

Empirical investigation on the influence of bent axial piston pumps' control systems' gains on hydraulic pipes stability

Dynamic Behavior of a Simple Rotor With Dissimilar Hydrodynamic Bearings by Modal Analysis

Vibration of Micro Plates in Electrostatic Fields Using Rayleigh-Ritz Method

Active control of whirling vibrations in boring trepanning association deep hole boring process using two electrodynamic shakers

Trajectory tracking and vibration control of two planar rigid manipulators moving a flexible object