scholarly journals Bio-Mechanical and Bio-Rheological Aspects of Sickle Red Cells in Microcirculation: A Mathematical Modelling Approach

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 322
Author(s):  
Purnima Chaturvedi ◽  
Rohit Kumar ◽  
Sapna Ratan Shah
Keyword(s):  
Low Cost ◽  
Biomechanical Model ◽  
Monogenic Disease ◽  
Cell Diameter ◽  
Governing Equations ◽  
Local Pressure ◽  
Lubricating Film ◽  
Cell Radius ◽  
Varying Viscosity ◽  
Modelling Approach

Sickle cell disease (SCD) is an inherited monogenic disease characterized by distorted red blood cells that causes vaso-occlusion and vasculopathy. Presently, electrophoresis of haemoglobin and genotyping are used as routine tests for diagnosis of the SCD. These techniques require specialized laboratories and are expensive. The low-cost microfluidics-based diagnostic tool holds a great attention for screening of red blood cell (RBC) deformability. In the present study, lubrication theory has been applied in order to develop a biomechanical model of microcirculation with altered rheological properties of sickle blood in the capillary, which is smaller in size compared to the cell diameter, to explain the multifactorial nature and pathogenesis of vaso-occlusion in SCD. The governing equations have been solved analytically for realistic boundary conditions and simulated using MATLAB. We found that the axial velocity of the cell decreases with a decrease in deformability and compliance. The height of the lubricating film predicts deformation of the cell with respect to local pressure in the microcirculation. Leak back and drag force depend non-linearly on the deformed cell radius with varying viscosity of the plasma and Reynolds number. The modelling predictions of this study is in coherence with experimental results. The analyzed parameters provide unique insights with novel possibilities to design a microfluidics-based effective therapeutic intervention for SCD.

scholarly journals Tolerance Modelling of Vibrations and Stability for Periodic Slender Visco-Elastic Beams on a Foundation with Damping. Revisiting

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3939
Author(s):  
Jarosław Jędrysiak
Keyword(s):  
Mathematical Modelling ◽  
System Of Differential Equations ◽  
Governing Equations ◽  
Asymptotic Homogenization ◽  
Elastic Beams ◽  
Oscillating Coefficients ◽  
Constant Coefficients ◽  
Tolerance Modelling ◽  
Tolerance Method ◽  
Modelling Approach

The mathematical modelling of certain problems of vibrations and stability for periodic slender visco-elastic beams is presented in this note. To consider these problems and take into account the effect of the microstructure, the tolerance modelling approach is proposed. Using this technique, the equation with non-continuous, periodic, highly oscillating coefficients is replaced by a system of differential equations with constant coefficients. Moreover, these governing equations describe the effect of the microstructure on the overall behavior of the beams under consideration. The tolerance modelling can lead to equations of two different tolerance models—the standard and the general, under weakened assumptions. This averaging tolerance method was assessed by comparison with the asymptotic homogenization, the governing equations of which omit this effect. My considerations were limited to proposing and presenting only mathematical models describing investigated beams. In a simple analytical example, the application of the presented average models is shown.

scholarly journals A highly flexible laboratory setup to demonstrate granular flow characteristics

2020 ◽  
Vol 104 (2) ◽  
pp. 1581-1596
Author(s):  
Thomas Heinze
Keyword(s):  
Granular Flow ◽  
Large Scale ◽  
Numerical Models ◽  
Low Cost ◽  
Experimental Investigations ◽  
Small Scale ◽  
Local Pressure ◽  
Slope Length ◽  
Runout Distance ◽  
Laboratory Setup

Abstract Dynamics of snow avalanches or landslides can be described by rapid granular flow. Experimental investigations of granular flow at laboratory scale are often required to analyze flow behaviour and to develop adequate mathematical and numerical models. Most investigations use image-based analysis, and additional sensors such as pressure gauges are not always possible. Testing various scenarios and parameter variations such as different obstacle shapes and positions as well as basal topography and friction usually requires either the construction of a new laboratory setups for each test or a cumbersome reconstruction. In this work, a highly flexible and modular laboratory setup is presented based on LEGO bricks. The flexibility of the model is demonstrated, and possible extensions for future laboratory tests are outlined. The setup is able to reproduce published laboratory experiments addressing current scientific research topics, such as overflow of a rigid reflector, flow on a bumpy surface and against a rigid wall using standard image-based analysis. This makes the setup applicable for quick scenario testing, e.g. for hypothesis testing or for low-cost testing prior to large-scale experiments, and it can contribute to the validation of external results and to benchmarks of numerical models. Small-scale laboratory setups are also very useful for demonstration purposes such as education and public outreach, both crucial in the context of natural hazards. The presented setup enables variation of parameters such as of slope length, channel width, height and shape, inclination, bed friction, obstacle position and shape, as well as density, composition, amount and grain size of flowing mass. Observable quantities are flow type, flow height, flow path and flow velocity, as well as runout distance, size and shape of the deposited material. Additional sensors allow further quantitative assessments, such as local pressure values.

Parametric Studies on a Numerical, Nonlinear Pulse Tube Flow

1997 ◽  
Vol 119 (4) ◽  
pp. 831-837 ◽  
Author(s):  
C. S. Kirkconnell ◽  
G. T. Colwell
Keyword(s):  
Numerical Model ◽  
High Reliability ◽  
Low Cost ◽  
Method Of Lines ◽  
Pulse Tube ◽  
Governing Equations ◽  
Modeling Tools ◽  
The Method Of Lines ◽  
Commercial Applications ◽  
The One

The need for high reliability, low cost, low vibration cryocoolers, for both military and commercial applications, has spawned and continues to drive the development of pulse tube cryogenic refrigerators. The expander contains no moving parts, yielding the potential for marked improvements in these areas. Though pulse tube refrigeration has been thoroughly studied, more accurate analytic and numerical modeling tools are needed to facilitate the development of thermodynamically efficient pulse tube cryocoolers to meet the needs of the user community. At present, one of the primary areas of modeling uncertainty is in the calculation of the dissipative losses occurring within the pulse tube itself. Toward this end, a numerical model was developed to solve the one-dimensional, nonlinear governing equations for heat and mass flow in a pulse tube. The governing equations are scaled for high-frequency (>60 Hz) pulse lube operation. The resulting system of nonlinear, time-dependent equations was solved directly using the method of lines. The numerical model was verified analytically using a representative set of equations with a known solution. A sensitivity analysis was performed to investigate the influence of different parameters on the solution.

scholarly journals Nonlinear stability of the one-domain approach to modelling convection in superposed fluid and porous layers

2010 ◽  
Vol 466 (2121) ◽  
pp. 2695-2705 ◽  
Author(s):  
Antony A. Hill ◽  
Magda Carr
Keyword(s):  
Porous Material ◽  
Boundary Conditions ◽  
Nonlinear Stability ◽  
Navier Stokes ◽  
Governing Equations ◽  
Porous Layers ◽  
Stability Bound ◽  
Interfacial Boundary ◽  
The One ◽  
Modelling Approach

Studies of the nonlinear stability of fluid/porous systems have been developed very recently. A two-domain modelling approach has been adopted in previous works, but was restricted to specific configurations. The extension to the more general case of a Navier–Stokes modelled fluid over a porous material was not achieved for the two-domain approach owing to the difficulties associated with handling the interfacial boundary conditions. This paper addresses this issue by adopting a one-domain approach, where the governing equations for both regions are combined into a unique set of equations that are valid for the entire domain. It is shown that the nonlinear stability bound, in the one-domain approach, is very sharp and hence excludes the possibility of subcritical instabilities. Moreover, the one-domain approach is compared with an equivalent two-domain approach, and excellent agreement is found between the two.

scholarly journals The method for diagnosing the activity of inflammatory bowel diseases based on a combination of electrical and viscoelastic parameters of erythrocytes and the level of fecal calprotectin

2021 ◽  
Vol 1 (6) ◽  
pp. 40-49
Author(s):  
M. V. Kruchinina ◽  
I. O. Svetlova ◽  
A. V. Azgaldyan ◽  
M. F. Osipenko ◽  
E. Yu. Valuiskikh ◽  
...  
Keyword(s):  
Inflammatory Bowel Diseases ◽  
Low Cost ◽  
Fecal Calprotectin ◽  
Cell Diameter ◽  
Average Cell ◽  
High Productivity ◽  
Viscoelastic Parameters ◽  
Combined Use ◽  
Bowel Diseases ◽  
Inflammatory Bowel

Purpose of the work: to present a method for diagnosing the activity of inflammatory bowel diseases based on a combination of electrical and viscoelastic parameters of erythrocytes and the level of fecal calprotectin.Materials and methods. We examined 109 patients (37.7±11.7 years) with IBD (50 with ulcerative colitis, 41 with Crohn’s disease, 18 patients with unclassified colitis), of which 36 patients were examined in dynamics for 0.5–1 years, and 53 surveyed comparison groups. Taking into account the observation in dynamics in 109 cases, the presence of exacerbation of IBD was established and in 36 cases — remission of the diseases. The electrical and viscoelastic parameters of erythrocytes were studied by dielectrophoresis. The level of fecal calprotectin was determined by ELISA (R-Biopharm, Germany).Results. Differentiating values have been established for a number of erythrocyte parameters: average cell diameter, polarizability at a frequency of 106 Hz, the velocity of movement of cells towards electrodes, amplitude of erythrocyte deformation at a frequency of 106 Hz, the summarized indicators of rigidity, viscosity, electrical conductivity, position of the crossover frequency and the level of fecal calprotectin to distinguish patients with IBD in stages of exacerbation and remission. The proposed method for the combined use of erythrocyte parameters and the level of fecal calprotectin provided sufficient diagnostic accuracy: sensitivity 91.9%, specificity 93.1%, accuracy index 92.3%. The advantages of this approach are minimally invasiveness, high productivity, independence of the definition from the qualifications and experience of a specialist, low cost and labor intensity, and acceptability for the patient. This approach allows to establish the presence of exacerbation or remission, regardless of the nosological form of IBD.Conclusion. The combined use of electrical and viscoelastic parameters of erythrocytes and the level of fecal calprotectin is promising for determining the activity of the disease in patients with IBD.

scholarly journals Use of amplicon-based sequencing for testing fetal identity and monogenic traits with single circulating trophoblast (SCT) prenatal diagnosis

2020 ◽  
Author(s):  
Xinming Zhuo ◽  
Qun Wang ◽  
Vossaert Liesbeth ◽  
Roseen Salman ◽  
Adriel Kim ◽  
...  
Keyword(s):  
Low Cost ◽  
Point Mutations ◽  
Prenatal Testing ◽  
Monogenic Disease ◽  
Nucleotide Polymorphisms ◽  
Isolated Cells ◽  
Maternal Cell ◽  
Fetal Cells ◽  
Modified Method ◽  
Reliable Differentiation

AbstractA major challenge for cell-based non-invasive prenatal testing (NIPT) is to distinguish individual presumptive fetal cells from maternal cells in female pregnancies. We have sought a rapid, robust, versatile, and low-cost next-generation sequencing method to facilitate this process. Toward this goal, single isolated cells underwent whole genome amplification prior to genotyping. Multiple highly polymorphic genomic regions (including HLA-A and HLA-B) with 10-20 very informative single nucleotide polymorphisms (SNPs) within a 200 bp interval were amplified with a modified method based on other publications. To enhance the power of cell identification, approximately 40 Human Identification SNP (Applied Biosystems) test amplicons were also utilized. This method allowed reliable differentiation of fetal and maternal cells. In fully informative cases, two haplotypes were found within the maternal reads, and fetal cells showed reads with one but not the second maternal haplotype while also showing a novel paternal haplotype absent in the mother. For SNP typing, at least 2 SNPs and 10% of informative SNPs were required to differentiate a fetal cell from a maternal cell. A paternal DNA sample is not required using this method. The assay also successfully detected point mutations causing Tay Sachs disease, cystic fibrosis, and hemoglobinopathies in single lymphoblastoid cells, and monogenic disease-causing mutations in three cell-based NIPT cases. This method could be applicable for any monogenic diagnosis.

scholarly journals Theoretical Analysis and Optimization of a Gloved Hand-arm System

2021 ◽  
Author(s):  
Oreoluwa Alabi ◽  
Sunit Kumar Gupta ◽  
Oumar Barry
Keyword(s):  
Harmonic Balance ◽  
Equations Of Motion ◽  
Biomechanical Model ◽  
Lumped Parameter Model ◽  
Human Hand ◽  
Governing Equations ◽  
Lumped Parameter ◽  
Hand Tool ◽  
Modeling Techniques ◽  
Linear Spring

Abstract Studies have shown that isolators in the form of anti-vibration gloves effectively reduce the transmission of unwanted vibration from vibrating equipment to the human hand. However, as most of these studies are based on experimental or modeling techniques, the level of effectiveness and optimum glove properties for better performance remains unclear. To fill this gap, hand-arm system dynamics with and without gloves are studied analytically in this work. In the current work, we use a lumped parameter model of the hand-arm system, with hand-tool interaction modeled as a linear spring-damper system. The resulting governing equations of motion are solved analytically using the method of harmonic balance. Parametric analysisis performed on the biomechanical model of the hand-armsystem with and without a glove to identify key design pa-rameters. It is observed that the effect of glove parameters on its performance is not repetitive and changes in the studied different frequency ranges. This observation further motivates us to optimize the glove parameters to minimize the overall transmissibility in different frequency ranges.

scholarly journals Performance Analysis and Optimization of an Ejector Refrigeration System Using Alternative Working Fluids under Critical and Subcritical Operation Modes

2021 ◽  
Author(s):  
Aggrey Mwesigye ◽  
Seth B. Dworkin
Keyword(s):  
Low Cost ◽  
Area Ratio ◽  
Environmentally Benign ◽  
Low Grade ◽  
Refrigeration System ◽  
Ejector System ◽  
Improved Model ◽  
Maintenance Requirements ◽  
Low Grade Heat ◽  
Modelling Approach

Ejector systems are receiving considerable attention due to their simplicity, lower maintenance requirements, use of low grade heat, longer lifespan and low cost. In this paper an improved model to predict the performance of an ejector refrigeration system under both the critical and subcritical modes of operation was developed and validated. The model predicts ejector performance more precisely compared to studies following the same modelling approach in the literature. Using the developed model, performances with environmentally benign refrigerants, including R1233zd(E), HFO1336mzz(Z), R1234ze(Z), R600, RE245fa2, and RE245fa2 as alternatives to R141b and R245fa were investigated. For ejector area ratios between 4.45 to 12.98, evaporator temperatures between 0oC and 16oC and condenser temperatures between 20 and 40oC, the optimal performance of the ejector system was determined. Results show that for each refrigerant, higher area ratios give higher coefficients of performance, but require higher generator temperatures for better critical condensing temperatures. R600 showed the best performance followed by R1234Ze(Z) and R1233Zd(E) for the entire range of parameters considered. Results further show that there is an optimum generator temperature at each area ratio that maximizes performance. The optimal generator temperature increases as the area ratio and the condensing temperature increase. An alternative and more convenient approach to optimize ejector performance has been suggested in this work.

Influence of piezo-viscous behavior and load on the effectiveness of inlet zone bump in unidirectional pure sliding EHL line contacts

2018 ◽  
Vol 70 (9) ◽  
pp. 1766-1773
Author(s):  
Punit Kumar
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Governing Equations ◽  
Local Pressure ◽  
Content Type ◽  
Elasticity Equations ◽  
Line Contacts ◽  
Lower Load ◽  
Inlet Zone ◽  
Lubricant Viscosity

Purpose The purpose of this paper is to introduce the concept of stationary inlet zone bump (IZB) for film thickness enhancement in unidirectional pure sliding elastohydrodynamic lubrication (EHL) line contacts and to investigate the effects of maximum Hertzian pressure (load) and piezo-viscous response on the effectiveness of IZB. Design/methodology/approach The numerical analysis involves the solution of Reynolds and elasticity equations. The well-established Doolittle–Tait equations are used herein to determine the lubricant viscosity and density as functions of local pressure, while the Carreau model is used to describe the lubricant rheology. The IZB is assumed to have a sinusoidal profile and it is present on the stationary surface. The governing equations are discretized using finite difference scheme and solved using the Newton–Raphson technique. Findings Two test oils, L7808 and SR600, with linear and exponential piezo-viscous responses in the inlet zone are considered here for comparison. The effectiveness of IZB in terms of film thickness enhancement is found to be more for SR600. Besides, IZB is found to be more effective at lower values of maximum Hertzian pressure. The bump needs to shift downstream at higher load to be as effective as at lower load. Originality/value This is the first paper to simulate EHL characteristics in the presence of a stationary IZB and to study the effect of various parameters on EHL effectiveness. The film thickness enhancement obtained here is remarkable and hence it is a novel and valuable contribution.

Three Dimensional Simulation and Repair of Skull Maxilla and Dentition Based on CT Scanning and Laser Sintering Technologies

2012 ◽  
Vol 538-541 ◽  
pp. 1857-1861
Author(s):  
Gong Xing Yan ◽  
Xiao Rong Wang
Keyword(s):  
Low Cost ◽  
Three Dimensional ◽  
Biomechanical Model ◽  
Ct Scanning ◽  
Element Model ◽  
Spiral Ct ◽  
Dimensional Finite Element ◽  
Modeling Material ◽  
Dimensional Simulation ◽  
Three Dimensional Finite Element

Obtain a prosthesis and carry out maxillofacial repair by rapid prototyping technology on the basis of three dimensional finite element model of maxilla skull and dentition which is obtained through preliminary restoration done on a skull exemplar as modeling material and through spiral CT scanning and three dimensional imaging technologies. Thus, a vivid restored three dimensional biomechanical model and prosthesis of maxilla skull and dentition is obtained, based on which, the form and functions can be restored well after repair. Individual defect model and prosthesis model can be built according to different plans designed for different patients. By which, a complete idea for maxilla and dentition repair can be achieved with pleasing in appearance on patients, low cost and less post-operative complications.

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