Determination Of Geometrical Dimensions Research Articles

Numerical investigation of the optical efficiency of a parabolic trough collector at different concentration ratios

ABSTRACT The Concentration Ratio (CR) is one of the first parameters defined before starting a Parabolic Trough Collector (PTC) construction project as it can easily provide access to the operating temperature and the determination of geometric dimensions. Few studies have been conducted to highlight the importance of the CR. Hence, this work aims to numerically analyze three models of PTC, A, B, and C, with different concentration ratios to perform a comparative analysis of impacts of this parameter in the size and optical efficiency of the models. We used the Monte Carlo Ray Tracing (MCRT) method through the SolTrace software to perform this study. From the results, we conclude that the CR has a considerable effect on the size and optical efficiency of the PTC. On average, the results presented showed that for every gain in PTC optical efficiency, it would be necessary to increase the concentration rate by . However, it is noticed that these gains are not linear and decrease as the concentration rate increases. Also, the increase in the CR leads to an increase in the rim angle, in the collector aperture width, and in the solar energy flux density around the absorber. Finally, the results we found were investigated and validated, presenting excellent agreement with other works in the literature.

Design and fabrication of micro-channels based fluid viscosity sensor

This paper presents the design and fabrication of polydimethylsiloxane (PDMS) based microfluidic channel integrated with piezoelectric micro-cantilever as fluid sensor. A finite element analysis is carried out to simulate fluid–structure interaction and estimate cantilever deflection under different fluidic flows at constant flow rate. The design of device is based on the material selection as well as determination of geometrical dimensions. In this proposed work, a piezoelectric material is selected for micro-cantilever beam on the silicon substrate. The micro-channel is fabricated from SU8 mould and the material selected for channel is PDMS. Fabrication was done by considering systematic steps toward optimization of shape and geometry involving soft lithography process. The results obtained are compared with the FEM based (COMSOL Multiphysics) model that is designed and analyzed prior to the experiment. Further, the experimental results showed a good agreement with the predicted values calculated by the simulated model. Thus, the device is successfully designed and fabricated for sensing different fluids.

Design and Fluid Structure Interaction Analysis of a Micro-Channel as Fluid Sensor

In this proposed work, the design and analysis of a flow sensor to be integrated into a micro-channel is presented. A finite element analysis is carried out to simulate fluid-structure interaction and estimate cantilever deflection under different fluidic flows at constant flow rate. The design of device is based on the determination of geometrical dimensions. A mathematical analysis describing the fluid mechanics and their interaction with the beam is also proposed. The mathematical model is done using finite-element analysis, and a complete formulation for design analysis is determined. Finite element method based Comsol Multiphysics simulations are used to optimize the design in order to determine the fluid velocities after interaction with the free end of the micro-cantilever beam. The device is successfully designed for sensing different fluids.

Modeling, Simulation, and Design Guidelines for Piezoresistive Affinity Cantilevers

This paper presents design guidelines for piezoresistive affinity cantilevers for operation in liquid environments. For the first time, we consider the interdependence of various functional elements (such as biological, mechanical, and electrical) of the cantilever, their dependence on material choice, microfabrication processes, and geometry, and the resultant effects on the mechanical and electrical sensitivities of the cantilever. The cantilever design guidelines that include material selection as well as determination of geometrical dimensions are proposed. As an example, we have designed and simulated a multilayer piezoresistive silicon nitride affinity cantilever for performance in a liquid environment under constraints imposed by microfabrication and electrical and mechanical considerations. Systematic steps toward optimization of geometrical dimensions include initial analytical estimates of geometrical dimensions, followed by finite-element modeling and analysis of such cantilevers under the applied surface stress. Simulation studies brought forth the limitation on maximum obtainable ΔR/R as well as the nonlinear behavior of the cantilever which was not observed in analytical estimates.

Optimal design of reconfigurable parallel machining systems

A reconfigurable machining system is usually a modularized system, and its configuration design concerns the selections of modules and the determination of geometric dimensions in some specific modules. All of its design perspectives from kinematics, dynamics, and control have to be taken into considerations simultaneously, and a multidisciplinary design optimization (MDO) tool is required to support the configuration design process. This paper presents a new MDO tool for reconfigurable machining systems, and it includes the following works: (i) the literatures on the computer-aided design of reconfigurable parallel machining systems have been reviewed with a conclusion that the multidisciplinary design optimization is essential, but no comprehensive design tool is available to reconfigurable parallel machining systems; (ii) a class of reconfigurable systems called reconfigurable tripod-based machining system has been introduced, its reconfiguration problem is identified, and the corresponding design criteria have been discussed; (iii) design analysis in all of the disciplines including kinematics, dynamics, and control have been taken into considerations, and design models have been developed to evaluate various design candidates; in particular, the innovative solutions to direct kinematics, stiffness analysis for the design configurations of tripod-based machines with a passive leg, and concise dynamic modelling have been provided; and (iv) A design optimization approach is proposed to determine the best solution from all possible configurations. Based on the works presented in this paper, a computer-aided design and control tool have been implemented to support the system reconfiguration design and control processes. Some issues relevant to the practical implementation have also been discussed.