scholarly journals An Analytic Analysis of the Diffusive-Heat-Flow Equation for Different Magnetic Field Profiles for a Single Magnetic Nanoparticle

2012 ◽  
Vol 2012 ◽  
pp. 1-22 ◽  
Author(s):  
Brenda Dana ◽  
Israel Gannot
Keyword(s):  
Magnetic Field ◽  
Heat Flow ◽  
Temperature Profile ◽  
Magnetic Nanoparticle ◽  
Temperature Response ◽  
Flow Equation ◽  
Maximum Temperature ◽  
Transient Temperature ◽  
Muscular Tissue ◽  
Temperature Increment

This study analytically analyzes the changes in the temperature profile of a homogenous and isotropic medium having the same thermal parameters as a muscular tissue, due to the heat released by a single magnetic nanoparticle (MNP) to its surroundings when subject to different magnetic field profiles. Exploring the temperature behavior of a heated MNP can be very useful predicting the temperature increment of it immediate surroundings. Therefore, selecting the most effective magnetic field profile (MFP) in order to reach the necessary temperature for cancer therapy is crucial in hyperthermia treatments. In order to find the temperature profile caused by the heated MNP immobilized inside a homogenous medium, the 3D diffusive-heat-flow equation (DHFE) was solved for three different types of boundary conditions (BCs). The change in the BC is caused by the different MF profiles (MFP), which are analyzed in this article. The analytic expressions are suitable for describing the transient temperature response of the medium for each case. The analysis showed that the maximum temperature increment surrounding the MNP can be achieved by radiating periodic magnetic pulses (PMPs) on it, making this MFP more effective than the conventional cosine profile.

scholarly journals Transient temperature distribution on the corneal endothelium during ophthalmic phacoemulsification: a numerical simulation using the nodeless variable element

2010 ◽  
Vol 4 (6) ◽  
pp. 885-892 ◽  
Author(s):  
Wiroj Limtrakarn ◽  
Somporn Reepolmaha ◽  
Pramote Dechaumphai
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Anterior Chamber ◽  
Heat Generation ◽  
Corneal Endothelium ◽  
Temperature Response ◽  
Maximum Temperature ◽  
Transient Temperature ◽  
Cataract Operation ◽  
Transient Temperature Distribution

Abstract Background: During cataract operation (phacoemulsification), a phaco needle-tip is inserted into the anterior chamber of eye. Then, heat is generated by the oscillation of the phaco needle, which may injury the corneal endothelial cells. There are no data available for temperature responses at the corneal endothelium to heat from the phaco needle during phacoemulsification. Objective: Investigate temperature distribution on the corneal endothelium during ophthalmic phacoemulsification using numerical simulation, and compare the transient temperature response to heat between balanced salt solution (BSS) and ophthalmic viscoelastic device (OVD), Viscoat®. Methods: Heat flux from a phaco needle was measured with thermal properties of BSS and AVS in an experimental setting. Then, nodeless variable finite element method was applied to predict temperature changes in the eye by the phaco needle inserted into the anterior chamber. The transient temperature distribution on the corneal endothelium was calculated at 10, 20, and 30 seconds after heat generation by the needle. Results: The heat generation of phaco needle without sleeve cover was 1.6 kW/m2. The numerical simulation showed that the maximum temperature occurs on the wound location at all times after heat generation by the phaco needle. Especially, at time 30 seconds, it was 49.2 and 41.7°C in BSS and OVD, respectively. The temperature elevation by the phaco needle was lower in OVD than BSS. Conclusion: Phacoemulsification is a heat-generating procedure performed between the anterior chamber structures of eye. During this procedure, OVD may protect the corneal endothelium against heat better than BSS.

Experimental and Theoretical Analysis of Transient Response of Plate Heat Exchangers in Presence of Nonuniform Flow Distribution

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
N. Srihari ◽  
Sarit K. Das
Keyword(s):  
Steady State ◽  
Heat Exchangers ◽  
Sudden Change ◽  
Temperature Response ◽  
Flow Distribution ◽  
Transient Temperature ◽  
Nonuniform Flow ◽  
Flow Rates ◽  
Plate Heat ◽  
Flow Maldistribution

Transient analysis helps us to predict the behavior of heat exchangers subjected to various operational disturbances due to sudden change in temperature or flow rates of the working fluids. The present experimental analysis deals with the effect of flow distribution on the transient temperature response for U-type and Z-type plate heat exchangers. The experiments have been carried out with uniform and nonuniform flow distributions for various flow rates. The temperature responses are analyzed for various transient characteristics, such as initial delay and time constant. It is also possible to observe the steady state characteristics after the responses reach asymptotic values. The experimental observations indicate that the Z-type flow configuration is more strongly affected by flow maldistribution compared to the U-type in both transient and steady state regimes. The comparison of the experimental results with numerical solution indicates that it is necessary to treat the flow maldistribution separately from axial thermal dispersion during modeling of plate heat exchanger dynamics.

On the in Vitro Hyperthermia of Magnetic Fluid in AC Magnetic Field

2009 ◽  
Author(s):  
Junfeng Jiang ◽  
Ruoyu Hong ◽  
Xiaohui Zhang ◽  
Hongzhong Li
Keyword(s):  
Magnetic Field ◽  
Magnetic Fluid ◽  
Volume Fraction ◽  
Maximum Temperature ◽  
Magnetic Fluid Hyperthermia ◽  
Ac Magnetic Field ◽  
Hyperthermia Therapy ◽  
Good Biocompatibility ◽  
High Chemical Stability

Hyperthermia therapy for cancer has attracted much attention nowadays. The study on the heat transfer in the magnetic fluid and the tumor is crucial for the successful application of magnetic fluid hyperthermia (MFH). Water-based Fe3O4 magnetic fluid is expected to be a most appropriate candidate for MFH due to the good biocompatibility, high saturation magnetization, super-paramagnetization and high chemical stability. In this paper, we explore the heat generation and transfer in magnetic fluid which is placed under an AC magnetic field. It is found that the amplitude and the frequency of alternating magnetic field, particle size and volume fraction have a pronounce influence on maximum temperature of hyperthermia.

Design and Fabrication of a Magnetocaloric Microcooler

2005 ◽  
Author(s):  
Sangchae Kim ◽  
Bharath Bethala ◽  
Simone Ghirlanda ◽  
Senthil N. Sambandam ◽  
Shekhar Bhansali
Keyword(s):  
Magnetic Field ◽  
Ambient Temperature ◽  
Temperature Change ◽  
Entropy Change ◽  
Temperature Sensors ◽  
Experimental Results ◽  
Maximum Temperature ◽  
Alternative Technology ◽  
Temperature Conditions ◽  
Si Wafer

Magnetocaloric refrigeration is increasingly being explored as an alternative technology for cooling. This paper presents the design and fabrication of a micromachined magnetocaloric cooler. The cooler consists of fluidic microchannels (in a Si wafer), diffused temperature sensors, and a Gd5(Si2Ge2) magnetocaloric refrigeration element. A magnetic field of 1.5 T is applied using an electromagnet to change the entropy of the magnetocaloric element for different ambient temperature conditions ranging from 258 K to 280 K, and the results are discussed. The tests show a maximum temperature change of 7 K on the magnetocaloric element at 258 K. The experimental results co-relate well with the entropy change of the material.

scholarly journals Magnetic Field Mapping Around Individual Magnetic Nanoparticle Agglomerates Using Nitrogen‐Vacancy Centers in Diamond

2021 ◽  
pp. 2100011
Author(s):  
Filipe Camarneiro ◽  
Juanita Bocquel ◽  
Juan Gallo ◽  
Manuel Bañobre‐López ◽  
Kirstine Berg‐Sørensen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticle ◽  
Nitrogen Vacancy ◽  
Field Mapping ◽  
Magnetic Field Mapping ◽  
Nitrogen Vacancy Centers ◽  
Nanoparticle Agglomerates

scholarly journals Aligned Fe3O4 magnetic nanoparticle films by magneto-electrospray method

RSC Advances ◽  
2017 ◽  
Vol 7 (64) ◽  
pp. 40124-40130 ◽  
Author(s):  
Christina W. Kartikowati ◽  
Qing Li ◽  
Shinji Horie ◽  
Takashi Ogi ◽  
Toru Iwaki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticle ◽  
Film Deposition ◽  
Nanoparticle Films ◽  
P Application ◽  
Fe3o4 Magnetic Nanoparticle

Application of magnetic field during film deposition by electrospray enhances the magnetic performances of the film. This enhancement increased as the diameter of the constituent nanoparticles increased.

Braking performance of a novel frictional-magnetic compound disc brake for automobiles

2018 ◽  
Vol 233 (10) ◽  
pp. 2443-2454 ◽  
Author(s):  
Yan Yin ◽  
Jiusheng Bao ◽  
Jinge Liu ◽  
Chaoxun Guo ◽  
Tonggang Liu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Temperature Rise ◽  
Friction Material ◽  
Maximum Temperature ◽  
Interface Temperature ◽  
Disc Brake ◽  
Braking Performance ◽  
Maximum Temperature Rise ◽  
Disc Brakes ◽  
Braking Torque

Disc brakes have been applied in various automobiles widely and their braking performance has vitally important effects on the safe operation of automobiles. Although numerous researches have been conducted to find out the influential law and mechanism of working condition parameters like braking pressure, initial braking speed, and interface temperature on braking performance of disc brakes, the influence of magnetic field is seldom taken into consideration. In this paper, based on the novel automotive frictional-magnetic compound disc brake, the influential law of magnetic field on braking performance was investigated deeply. First, braking simulation tests of disc brakes were carried out, and then dynamic variation laws and mechanisms of braking torque and interface temperature were discussed. Furthermore, some parameters including average braking torque, trend coefficient and fluctuation coefficient of braking torque, average temperature, maximum temperature rise, and the time corresponding to the maximum temperature rise were extracted to characterize the braking performance of disc brakes. Finally, the influential law and mechanism of excitation voltage on braking performance were analyzed through braking simulation tests and surface topography analysis of friction material. It is concluded that the performance of frictional-magnetic compound disc brake is prior to common brake. Magnetic field is greatly beneficial for improving the braking performance of frictional-magnetic compound disc brake.

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