S. Wiak

Biogeography-Inspired Multiobjective Optimization and MEMS Design

A new version of the biogeography-based optimization algorithm is proposed in order to consider multiple objectives. In fact, by exploiting non-dominated sorting of habitats, it is possible to approximate Pareto-optimal solutions in the objective space. The optimal shape design of an electrostatic micromotor, which is a benchmark in the Micro Electro-Mechanical Systems design, is considered as the case study.

3-D computer aided analysis of the "Berkeley" electrostatic micromotor

The basic ideas of IC-processed electrostatics are reviewed. The three-dimensional field model of a variable-capacitance electrostatic micromotor is then presented and the underlying analysis problem is solved by means of the finite element method. The micromotor, acting as a position actuator, is investigated at steady state and particular attention is paid in the calculation of the torque-angle curve featuring the device. The influence of stator geometry on the electromechanical performance is also investigated and design considerations are accordingly drawn. Finally, the step-transient response of the actuator is simulated. >

Optimal shape design of electrostatic microactuators: A multiobjective formulation

A procedure of automated optimal design of a class of micro-electromechanical devices is proposed in terms of a multiobjective optimization formulation. A comb-drive electrostatic accelerometer is considered as the case study. By optimiz- ing the shape design of the device, it is desired to extend the actuation range of the comb drive in steady-state conditions, leading to greater gap distances between the electrodes. The design variables control the geometry of fixed and movable electrodes, in terms of width and height. The twofold goal of maximizing the drive force considered as the main criterion, while minimizing the levitation force considered as a parasitic effect, makes it possible to implement a Pareto optimality approach.

Analysis of influence of rotor design on high speed small power induction motors parameters

This paper presents the analysis of the influence of rotor design: massive or cage on high speed small power induction motors parameters. For these analyzes were used both field-circuit method and circuit analytical method. As could be predicted massive rotor motor is characterized by higher losses and thus less efficiency than the squirrel cage motor, especially with copper cage. Despite the massive motors are easier to manufacture and the specific construction may be used.

Minimizing design criterion and sensitivity: Cost-effective evolutionary approach with application in mechatronics

Optimizing against sensitivity is a major issue in optimal design of electromagnetic devices. In the paper, the optimal shape design problem against sensitivity is formulated in terms of Paretian optimality, trading off design criterion and sensi- tivity with respect to large-scale variations in the design space; a cost-effective evaluation of sensitivity, based on evolutionary computing, is proposed. The design optimization of a magnetic MEMS is considered as the case study.

Comparative study of 3-D computer models of RF ablation probes

The paper focus is on the generation of 3-D field models of probes for Radio-Frequency Ablation (RFA). The authors propose a multiphysics three-dimensional models for curved-electrode probes, which can be used to optimize placement and exploitation of the probes. The first model consists of tumor tissue and liver tissue. The second one is extended by fat tissue. The diameter of whole model is thirty centimetres, which corresponds to the waist size of the adult human. Both conduction field and transient thermal field in the tissues are simulated by means of finite-element method.

Field Simulation Of The Elevation Force In ARotating Electrostatic Microactuator

During the last decade, a renewed interest has grown about electrostatic motors in the microscopic scale, owing to the impressive developments in the technology of integrated electrostatics. Since friction has a crucial effect on micromotors efficiency, from the designer viewpoint it is important to identify new device geometries able to improve the mechanical response. After discussing the major sources of friction in a rotating microactuator, a case study is presented; in particular, a geometry reducing the dry friction is identified and discussed.