An Ohmic Heating Model Based on the Thermal Circuit Method: Case of Study for Parameter Determination

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Gerardo Marx Chávez-Campos ◽  
Adriana del Carmen Téllez-Anguiano ◽  
Juan Alfonso Salazar-Torres ◽  
Héctor Javier Vergara-Hernández ◽  
Octavio Vazquez-Gómez
Keyword(s):  
Ohmic Heating ◽  
Experimental System ◽  
Parameter Determination ◽  
Heating Systems ◽  
The Laplace Transform ◽  
Computational Fluid Dynamics Cfd ◽  
Heating Model ◽  
The Right ◽  
Wide Potential ◽  
Analog Parameters

Abstract Currently, ohmic heating is a method with a wide potential as an alternative thermal process in the industry. However, the success of this method depends on the rate of the generated heat by the right material’s selection and its geometry. Due to its complexity, the heating systems are usually modeled by computational fluid dynamics (CFD) or finite element method (FEM). However, in this paper, an alternative model representation was used, and this model does not consider the temperature gradients and uses thermal resistance and capacitance as steady-state and transient analog parameters. The parameters are calculated using matlab considering the geometry, as well as the electrical and thermal properties of the material to heat. The proposed circuit is solved by applying the Laplace transform. Finally, the temperature performance of the model and the experimental system are compared with noncontrolled and controlled experiments.

scholarly journals Effects of bone cement filling in rabbit proximal femoral medullary cavity on distal femoral blood flow and metabolism

2018 ◽  
Vol 46 (12) ◽  
pp. 5237-5244
Author(s):  
Li-Cheng Xi ◽  
Hong-Yu Li ◽  
Ming Zhang ◽  
Si-Cheng Huang
Keyword(s):  
Blood Flow ◽  
Bone Cement ◽  
Rabbit Model ◽  
Experimental System ◽  
Medullary Cavity ◽  
Marrow Cavity ◽  
Femoral Blood Flow ◽  
Femoral Blood ◽  
The Right ◽  
Time Point

Objective A rabbit model was used to evaluate the effects of bone-cemented hip arthroplasty on distal femoral blood flow and metabolism relative to that of the non-cemented contralateral leg. Methods The marrow cavity of the right hind femur was filled with bone cement. At each of the following time points, rabbits were randomly selected to receive an injection of one dose of 99mTc-methylene diphosphonate and then immediately scanned using a gamma camera: immediately postoperatively and at 4 and 8 weeks postoperatively. A BL-410 model biofunction experimental system was used to analyze the acquired images and determine the radioactive counts of each hind leg. Results The X-ray and photographic images of the right femoral bones confirmed successful filling of the marrow cavity with bone cement. The radioactive counts were significantly lower in the experimental than control legs at each time point. The ratio of the radioactive count of the experimental to control leg increased considerably at each time point, but each ratio was <1. Conclusion Blocking the proximal femoral medullary cavity with bone cement was associated with significant lowering of the blood circulation of the femur and marrow, decreasing the distal femoral blood flow and bone metabolic rate.

Review of Cardiac Pacemaker Lead Designs for Computational Models in a VR Environment

2017 ◽  
Author(s):  
Bethany Tourek ◽  
Dan Orban ◽  
Lingyu Meng ◽  
Hakizumwami Birali Runesha ◽  
Dan Keefe ◽  
...  
Keyword(s):  
Computational Models ◽  
Cardiac Pacemaker ◽  
Model Complexity ◽  
Element Analysis ◽  
Parameterized Design ◽  
Pacemaker Leads ◽  
Computational Fluid Dynamics Cfd ◽  
The Right ◽  
Implantable Cardiac Pacemaker ◽  
Computational Resources

An implantable cardiac pacemaker is used to modify and treat irregular heartbeats [1] and invented in 1958 [2]. Devices have no fixation or fixed to the heart wall. No fixation leads lay in the bottom of heart cavities, while fixed leads have tines (passive) or a helix screw (active) to attach to the heart. Lead geometries and material properties vary between companies, with geometric sizing based primarily on the internal mechanics of the lead. Finite element analysis (FEA), computational fluid dynamics (CFD) and bench-top simulations are used to evaluate cardiac leads. These simulations analyze only one lead and struggle to compare and test variations in lead designs. Advanced computational resources can run many computer simulations of anatomical environments, however model complexity increases the time to run each simulation. To address this issue, we present a simplified parameterized design space for cardiac pacemaker leads in the right atrium. This information will be used to run multiple simulations of leads in blood flow, for visualization in a single virtual reality (VR) environment and allow the designer to iterate through many design variations (See Figure 1).

Contribution of Superior Mesenteric Vein Flow to the Right and Left Lobes of the Liver Using CFD

2009 ◽  
Author(s):  
Stephanie M. George ◽  
Diego R. Martin ◽  
Don P. Giddens
Keyword(s):  
Portal Vein ◽  
Superior Mesenteric Vein ◽  
Splenic Vein ◽  
Normal Subjects ◽  
Diagnostic Techniques ◽  
Mesenteric Vein ◽  
Right Lobe ◽  
Computational Fluid Dynamics Cfd ◽  
The Right ◽  
End Stage

The incidence of cirrhosis, the end stage for many liver diseases, is rising and with it the need for better understanding of the progression of the disease and diagnostic techniques. The authors have noted that liver disease occurs preferentially in the right side of the liver which is the largest lobe. One hypothesis is that this is due to the composition of the blood that supplies the right lobe. The liver is fed by both the hepatic artery and the portal vein with the portal vein contributing about 80% of the blood supply. The portal vein (PV) is supplied by the superior mesenteric vein (SMV), which drains blood from the digestive track, and the splenic vein (SV), which drains blood from the spleen. Since the blood in the SMV is coming from the digestive track, it carries toxins and items absorbed during digestion. Toxins such as alcohol are known to damage the liver. Thus, our hypothesis is that the majority of the SMV flow feeds into the right portal vein and ultimately the right lobe of the liver. This study seeks to assess the validity of our hypothesis in four subjects by creating subject specific models in two normal subjects and two patients and using computational fluid dynamics (CFD) to calculate the SMV contribution to the right portal vein.

scholarly journals Asymptotic Stability for an Axis-Symmetric Ohmic Heating Model in Thermal Electricity

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Anyin Xia ◽  
Mingshu Fan ◽  
Shan Li
Keyword(s):  
Electrical Resistivity ◽  
Asymptotic Behavior ◽  
Ohmic Heating ◽  
The Other ◽  
Dimensionless Temperature ◽  
Nonlocal Term ◽  
Unique Equilibrium ◽  
Heating Model ◽  
Current Flows ◽  
Uniformly Bounded

The asymptotic behavior of the solution for the Dirichlet problem of the parabolic equation with nonlocal termut=urr+ur/r+f(u)/(a+2πb∫01‍f(u)rdr)2,for  0<r<1,  t>0,u1,t=u′(0,t)=0,for  t>0,  ur,0=u0r,  for  0≤r≤1. The model prescribes the dimensionless temperature when the electric current flows through two conductors, subject to a fixed potential difference. One of the electrical resistivity of the axis-symmetric conductor depends on the temperature and the other one remains constant. The main results show that the temperature remains uniformly bounded for the generally decreasing functionf(s), and the global solution of the problem converges asymptotically to the unique equilibrium.

scholarly journals Response of Fractionally Damped Beams with General Boundary Conditions Subjected to Moving Loads

2012 ◽  
Vol 19 (3) ◽  
pp. 333-347 ◽  
Author(s):  
R. Abu-Mallouh ◽  
I. Abu-Alshaikh ◽  
H.S. Zibdeh ◽  
Khaled Ramadan
Keyword(s):  
Dynamic Response ◽  
Boundary Conditions ◽  
Fractional Derivative ◽  
Fractional Derivatives ◽  
Initial Conditions ◽  
General Boundary ◽  
General Boundary Conditions ◽  
Damping Characteristics ◽  
The Laplace Transform ◽  
The Right

This paper presents the transverse vibration of Bernoulli-Euler homogeneous isotropic damped beams with general boundary conditions. The beams are assumed to be subjected to a load moving at a uniform velocity. The damping characteristics of the beams are described in terms of fractional derivatives of arbitrary orders. In the analysis where initial conditions are assumed to be homogeneous, the Laplace transform cooperates with the decomposition method to obtain the analytical solution of the investigated problems. Subsequently, curves are plotted to show the dynamic response of different beams under different sets of parameters including different orders of fractional derivatives. The curves reveal that the dynamic response increases as the order of fractional derivative increases. Furthermore, as the order of the fractional derivative increases the peak of the dynamic deflection shifts to the right, this yields that the smaller the order of the fractional derivative, the more oscillations the beam suffers. The results obtained in this paper closely match the results of papers in the literature review.

Air Flow and Heat Transfer in a Temperature-Controlled Open Top Enclosure

2012 ◽  
Author(s):  
Charlotte Barbier ◽  
Paul J. Hanson ◽  
Donald E. Todd ◽  
Damen Belcher ◽  
Eriks W. Jekabson ◽  
...  
Keyword(s):  
Wind Speed ◽  
Operating Cost ◽  
Cfd Simulations ◽  
Heating Systems ◽  
Elevated Atmospheric Co2 ◽  
Heating Efficiency ◽  
Oak Ridge ◽  
Flow And Heat Transfer ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd

A large 12-meter-diameter open top enclosure (OTE) equipped with two unique belowground and above ground heating systems was built and intensively tested in Oak Ridge, TN, USA. The OTE is a prototype for use within an environmental change experiment, in which replica units will be built in Minnesota to assess the response of northern peatland ecosystems to increases in temperature and elevated atmospheric CO2. For several months, temperatures, energy, wind speed and relative humidity were monitored throughout the enclosure space to assess the enclosure performance and efficiency. In parallel, Computational Fluid Dynamics (CFD) simulations were performed with ANSYS-CFX to investigate the impacts of external wind, buoyancy, and OTE design on the temperatures achieved within the enclosure. The addition of a frustum that partially reduced the top opening was also investigated experimentally and numerically. The OTE is capable of achieving a temperature differential of at least +6°C for air using a combination of 8 electrical heaters. Differential temperatures were sustained for several months. The experimental data and the numerical results showed that the addition of a frustum dramatically decreases the operating cost of the OTE and leads to better control over the differential air temperature in the enclosure. Buoyancy forces and winds heavily impacted enclosure performance. It was also found that the heating efficiency of the OTE depends mainly on the wind speed, and that there exists a critical wind speed at which the heating efficiency is the highest.

scholarly journals Process parameter determination for small recycling plants for the production of filament for FFF printing using the Taguchi method

2021 ◽  
Author(s):  
Sascha Hartig ◽  
Lennart Hildebrandt ◽  
Marc Fette ◽  
Tobias Meyer ◽  
Eugen Musienko ◽  
...  
Keyword(s):  
Taguchi Method ◽  
Process Parameters ◽  
Small Businesses ◽  
Cooling Capacity ◽  
Parameter Determination ◽  
Single Screw Extruder ◽  
Machine Manufacturer ◽  
Compact Design ◽  
The Right ◽  
House Production

AbstractWith the increasing use of the filament fabrication process, the in-house production of filament and the recycling of PLA waste is becoming more and more important. Small desktop filament extruders with associated peripherals enable small businesses and private users to carry out these recycling processes. Determing the right process parameters is of crucial importance here. These are usually only issued by the polymer manufacturer and the machine manufacturer. However, the development of own process parameters is important for new polymer compounds, as well as polymers with unknown manufacturers, as is typical in recycling. The common Taguchi method, which is used for process optimisation within the FFF process, was also used in this article to produce improved parameter sets for the production of filament using a single screw extruder (3devo Precision) with four heating zones. In this experimental field, the Taguchi method did not prove promising. Due to the small dimensions and compact design of such desktop filament extrusion machines, it was found that the setting parameters cannot be considered independently. The main parameters influencing the process were identified as the extruder screw speed, the cooling capacity and the temperature of the heating coil at the hopper. Nevertheless, parameter sets for PLA pellets and recycled PLA could be developed which have a better performance in terms of homogeneity of the diameter over time compared to the previously available parameter sets.

Computational Fluid Dynamics Simulation of the Right Coronary Artery Moving With the Cardiac Wall

2002 ◽  
Author(s):  
H. Hayashi ◽  
T. Yamaguchi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Coronary Artery ◽  
Right Coronary Artery ◽  
Cfd Simulation ◽  
Dynamics Simulation ◽  
Cardiac Wall ◽  
Computational Fluid Dynamics Cfd ◽  
The Right ◽  
Heart Wall

The beating motion of the heart wall, to which the major coronary arteries are fixed, is interesting, due to its possible mechanical influence on the flow inside the artery, and hence its effect on atherogenesis [1–2]. In this study, we conducted a computational fluid dynamics (CFD) simulation using a simplified model of the right coronary artery, which deforms with heart contractions. The results are discussed with respect to the local hemodynamics characteristics, particularly the streamline pattern and the wall shear stress distribution.

Validation of an Open Source Framework for the Simulation of Blood Flow in Rigid and Deformable Vessels

2013 ◽  
Author(s):  
T. Passerini ◽  
A. Quaini ◽  
U. Villa ◽  
A. Veneziani ◽  
S. Canic
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Numerical Methods ◽  
Open Source ◽  
Open Source Framework ◽  
Computational Fluid Dynamics Cfd ◽  
Scientific Endeavor ◽  
The Right ◽  
Computational Analyses

Computational methods are the tool of choice for the study of physics phenomena in many fields of scientific endeavor. To guarantee the reliability of the results of computational analyses, it is crucial that mathematical models are validated and numerical methods are verified. A verified method is capable of correctly solving the problem equations, while a valid model is able to correctly describe the features of the problem (i.e. it uses the right equations). In this paper we: (i) verify and validate an open source computational fluid dynamics (CFD) framework for the solution of problems of interest in hemodynamics and (ii) provide a report on the methodology that we use, to make our experiences reproducible.

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