Study of Liquid-Metal Based Heating Method for Temperature Gradient Focusing Purpose

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
M. Gao ◽  
L. Gui ◽  
J. Liu
Keyword(s):  
Optimal Design ◽  
Temperature Gradient ◽  
Liquid Metal ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Microfluidic Channels ◽  
Heating Method ◽  
Electrical Heater ◽  
Temperature Gradient Focusing ◽  
A New Technique

Temperature gradient focusing (TGF) is a highly efficient focusing technique for the concentration and separation of charged analytes in microfluidic channels. The design of an appropriate temperature gradient is very important for the focusing efficiency. In this study, we proposed a new technique to generate the temperature gradient. This technique utilizes a microchannel filled with liquid-metal as an electrical heater in a microfluidic chip. By applying an electric current, the liquid-metal heater generates Joule heat, forming the temperature gradient in the microchannel. To optimize the temperature gradient and find out the optimal design for the TGF chip, numerical simulations on four typical designs were studied. The results showed that design 1 can provide a best focusing method, which has the largest temperature gradient. For this best design, the temperature is almost linearly distributed along the focusing microchannel. The numerical simulations were then validated both theoretically and experimentally. The following experiment and theoretical analysis on the best design also provide a useful guidance for designing and fabricating the liquid-metal based TGF microchip.

Design of Liquid-Metals Heating-Induced Temperature Gradient Focusing in Microfluidic Channels

2012 ◽  
Author(s):  
Meng Gao ◽  
Lin Gui ◽  
Jing Liu
Keyword(s):  
Temperature Gradient ◽  
Microfluidic Chip ◽  
Liquid Metals ◽  
Electrical Current ◽  
Microfluidic Channels ◽  
Linear Temperature ◽  
Linear Temperature Gradient ◽  
Temperature Gradient Focusing ◽  
Clear Guideline ◽  
A New Technique

Temperature gradient focusing (TGF) is a highly efficient focusing technique for the concentration and separation of charged analytes in microfluidic channels. Design and control of an appropriate temperature gradient are very important for protein concentration and separation. In this study, we propose a new technique to generate the temperature gradient for the focusing purpose. This technique utilizes a microchannel filled with liquid-metals as a heater in the microfluidic chip. By applying electrical current, the liquid-metal microchannel generates Joule heat to form temperature gradient in the microfluidic chip. To optimize the temperature gradient, several typical designs were investigated. The results show the best design which provides the largest linear temperature gradient. The parametric studies present a clear guideline for designing aTGF microfluidic chip.

scholarly journals Optimal Design of Tolerance Ring in Double-Decker Catcher Bearing System

2015 ◽  
Vol 9 (1) ◽  
pp. 618-623 ◽  
Author(s):  
Zhu Yili ◽  
Zhang Yongchun
Keyword(s):  
Optimal Design ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Design Parameters ◽  
Impact Forces ◽  
Double Decker ◽  
Amb System ◽  
Bearing System

In an active magnetic bearing (AMB) system, the catcher bearings (CBs) are essential to protect the system in cases of AMB failure. On the basis of the former researches of double-decker catcher bearings (DDCBs), a tolerance ring is proposed to further improve the performance of DDCB. Firstly, the support model of DDCB supported by tolerance ring is established. Then numerical simulations are carried out to determine the design parameters of tolerance ring. Finally, the tolerance ring is manufactured according to the obtained parameters and relative experiments are carried out to verify the theoretical analysis results. Both theoretical and experimental results validated that proper tolerance ring is beneficial to reduce the following impact forces and vibrations after rotor drop.

OPTIMAL DESIGN OF THE NACELLE ASSEMBLY UNDER THE WING OF AN AIRLINER BASED ON RANS NUMERICAL SIMULATIONS

2015 ◽  
Vol 46 (5) ◽  
pp. 439-464
Author(s):  
Nikolay Alekseevich Zlenko ◽  
Innokentii Aleksandrovich Kursakov
Keyword(s):  
Optimal Design ◽  
Numerical Simulations

scholarly journals Theoretical Analysis and Design of an Innovative Coil Structure for Transcranial Magnetic Stimulation

2021 ◽  
Vol 11 (4) ◽  
pp. 1960
Author(s):  
Naming Zhang ◽  
Ziang Wang ◽  
Jinhua Shi ◽  
Shuya Ning ◽  
Yukuo Zhang ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Transcranial Magnetic Stimulation ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Magnetic Stimulation ◽  
Influential Factors ◽  
Intersection Angle ◽  
Electromagnetic Field Distribution ◽  
Analysis And Design ◽  
Coil Structure

Previous research showed that pulsed functional magnetic stimulation can activate brain tissue with optimum intensity and frequency. Conventional stimulation coils are always set as a figure-8 type or Helmholtz. However, the magnetic fields generated by these coils are uniform around the target, and their magnetic stimulation performance still needs improvement. In this paper, a novel type of stimulation coil is proposed to shrink the irritative zone and strengthen the stimulation intensity. Furthermore, the electromagnetic field distribution is calculated and measured. Based on numerical simulations, the proposed coil is compared to traditional coil types. Moreover, the influential factors, such as the diameter and the intersection angle, are also analyzed. It was demonstrated that the proposed coil has a better performance in comparison with the figure-8 coil. Thus, this work suggests a new way to design stimulation coils for transcranial magnetic stimulation.

Mathematical Model Establishment and Analysis on the Pipe Deformation under External Pressure with the Ovality

2013 ◽  
Vol 760-762 ◽  
pp. 2263-2266
Author(s):  
Kang Yong ◽  
Wei Chen
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Yield Strength ◽  
Residual Stresses ◽  
Numerical Simulations ◽  
Significant Influence ◽  
External Pressure ◽  
Pipe Diameter ◽  
Axial Loads ◽  
The Stability

Beside the residual stresses and axial loads, other factors of pipe like ovality, moment could also bring a significant influence on pipe deformation under external pressure. The Standard of API-5C3 has discussed the influences of deformation caused by yield strength of pipe, pipe diameter and pipe thickness, but the factor of ovality degree is not included. Experiments and numerical simulations show that with the increasing of pipe ovality degree, the anti-deformation capability under external pressure will become lower, and ovality affecting the stability of pipe shape under external pressure is significant. So it could be a path to find out the mechanics relationship between ovality and pipe deformation under external pressure by the methods of numerical simulations and theoretical analysis.

Joule Heating Induced Temperature Gradient Focusing for Microfluidic Concentration of Samples

2010 ◽  
Author(s):  
Zhengwei Ge ◽  
Chun Yang
Keyword(s):  
Temperature Gradient ◽  
Electric Field ◽  
Joule Heating ◽  
Field Experiments ◽  
Dc Voltage ◽  
Sample Concentration ◽  
Great Achievement ◽  
Temperature Gradient Focusing ◽  
Concentration Enhancement ◽  
High Frequency Ac

Microfluidic concentration of sample species is achieved using the temperature gradient focusing (TGF) in a microchannel with a step change in the cross-section under a pure direct current (DC) field or a combined alternating current (AC) and DC electric field. Experiments were carried out to study the effects of applied voltage, buffer concentration and channel size on sample concentration in the TGF processes. These effects were analyzed and summarized using a dimensionless Joule number that is introduced in this study. In addition, Joule number effect in the Poly-dimethylsiloxane (PDMS)/PDMS microdevice was compared with the PDMS/Glass microdevice. A more than 450-fold concentration enhancement was obtained within 75 seconds in the PDMS/PDMS microdevice. Results also showed that the high frequency AC electric field which contributes to produce the temperature gradient and reduces the required DC voltage for the sample concentration. The lower DC voltage has generated slower electroosmotic flow (EOF), which reduces the backpressure effect associated with the finite reservoir size. Finally, a more than 2500-fold concentration enhancement was obtained within 14 minutes in the PDMS/PDMS microdevice, which was a great achievement in this TGF technique using inherent Joule heating effects.

Optothermal Analyte Manipulation With Temperature Gradient Focusing

2010 ◽  
Author(s):  
M. Akbari ◽  
M. Bahrami ◽  
D. Sinton
Keyword(s):  
Temperature Gradient ◽  
Heat Source ◽  
Optical System ◽  
Fluorescent Dye ◽  
Source Position ◽  
Video Projector ◽  
Temperature Gradient Focusing ◽  
Arbitrary Location ◽  
And Control ◽  
Preconcentration Method

An optothermal analyte preconcentration method is introduced in this work based on temperature gradient focusing. The present approach offers a flexible, noncontact technique for focusing and transporting of analytes. Here, we use a commercial video projector and an optical system to generate heat and control the heat source position, size and power. This heater is used to focus a sample model analyte, fluorescent dye, at an arbitrary location along the microchannel. Optothermal manipulation of the focused band was demonstrated by projecting a series of images with a moving light band.

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