scholarly journals Mathematical Modeling and Pointwise Validation of a Spouted Bed Using an Enhanced Bed Elasticity Approach

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4738
Author(s):  
Sebastián Uribe ◽  
Binbin Qi ◽  
Omar Farid ◽  
Muthanna Al-Dahhan
Keyword(s):  
Modulus Of Elasticity ◽  
Strain Tensor ◽  
Experimental Studies ◽  
Experimental Measurements ◽  
Spouted Bed ◽  
Cross Sectional ◽  
Spouted Beds ◽  
Solids Holdup ◽  
Model Predictions ◽  
Relative Errors

With a Euler–Euler (E2P) approach, a mathematical model for predicting the pointwise hydrodynamic behavior of a spouted bed was implemented though computational fluid dynamics (CFD) techniques. The model considered a bed elasticity approach in order to reduce the number of required sub-models to provide closure for the solids stress strain-tensor. However, no modulus of elasticity sub-model for a bed elasticity approach has been developed for spouted beds, and thus, large deviations in the predictions are obtained with common sub-models reported in literature. To overcome such a limitation, a new modulus of elasticity based on a sensitivity analysis was developed and implemented on the E2P model. The model predictions were locally validated against experimental measurements obtained in previous studies. The experimental studies were conducted using our in-house developed advanced γ-ray computed tomography (CT) technique, which allows to obtain the cross-sectional time-averaged solids holdup distribution. When comparing the model predictions against the experimental measurements, a high predictive quality for the radial solids holdup distribution in the spout and annulus regions is observed. The model predicts most of the experimental measurements for different particle diameters, different static bed heights, and different inlet velocities with deviations under 15%, with average absolute relative errors (AARE) between 5.75% and 7.26%, and mean squared deviations (MSD) between 0.11% and 0.24%

Diagnostics of metal samples using the results of experimental and theoretical study of positively charged microparticles formed upon sample destruction

2018 ◽  
Vol 84 (10) ◽  
pp. 23-28
Author(s):  
D. A. Golentsov ◽  
A. G. Gulin ◽  
Vladimir A. Likhter ◽  
K. E. Ulybyshev
Keyword(s):  
Experimental Data ◽  
Early Stage ◽  
Experimental Studies ◽  
Material Model ◽  
Total Charge ◽  
Cross Sectional ◽  
Practical Applications ◽  
Mechanical And Electrical Properties ◽  
Order Of Magnitude ◽  
Using Data

Destruction of bodies is accompanied by formation of both large and microscopic fragments. Numerous experiments on the rupture of different samples show that those fragments carry a positive electric charge. his phenomenon is of interest from the viewpoint of its potential application to contactless diagnostics of the early stage of destruction of the elements in various technical devices. However, the lack of understanding the nature of this phenomenon restricts the possibility of its practical applications. Experimental studies were carried out using an apparatus that allowed direct measurements of the total charge of the microparticles formed upon sample rupture and determination of their size and quantity. The results of rupture tests of duralumin and electrical steel showed that the size of microparticles is several tens of microns, the particle charge per particle is on the order of 10–14 C, and their amount can be estimated as the ratio of the cross-sectional area of the sample at the point of discontinuity to the square of the microparticle size. A model of charge formation on the microparticles is developed proceeding from the experimental data and current concept of the electron gas in metals. The model makes it possible to determine the charge of the microparticle using data on the particle size and mechanical and electrical properties of the material. Model estimates of the total charge of particles show order-of-magnitude agreement with the experimental data.

scholarly journals Pain acceptance and its impact on function and symptoms in fibromyalgia

2020 ◽  
Vol 20 (4) ◽  
pp. 727-736 ◽  
Author(s):  
Synne Flatlandsmo Tangen ◽  
Anne-Sofie Helvik ◽  
Hilde Eide ◽  
Egil A. Fors
Keyword(s):  
Chronic Pain ◽  
Linear Regression ◽  
Burden Of Illness ◽  
Longitudinal Design ◽  
Fibromyalgia Impact Questionnaire ◽  
Experimental Studies ◽  
Outcome Variable ◽  
Unknown Etiology ◽  
Cross Sectional ◽  
Pain Acceptance

AbstractObjectivesFibromyalgia is a chronic widespread pain (CWP) syndrome of unknown etiology with substantial burden of illness and functional impairment. Pain acceptance has emerged as an interesting target of therapy in chronic pain populations, but few studies have yet been done on the effect of pain acceptance on patients with fibromyalgia. The aim of the present study was to examine the relationship between pain acceptance and its impact on function and symptoms in fibromyalgia with both a cross-sectional and longitudinal design.MethodsThree hundred and sixty five participants aged 22–70 with fibromyalgia were recruited from the Norwegian Fibromyalgia Association (NFA). They filled out a questionnaire containing the Fibromyalgia Impact Questionnaire (FIQ), measurement of function and symptoms, and Chronic Pain Acceptance Questionnaire (CPAQ), measurement of pain acceptance, in addition to sociodemographic and clinical variables such as degree of fibromyalgia, depression and pain duration (T1 measures). One year after, 87 of the participants filled out the FIQ and clinical measures once again (T2 measures). Unadjusted and adjusted linear regression analyses were performed both for cross-sectional measures at T1 and for longitudinal measures from T1 to T2, with FIQ score as the outcome variable and CPAQ score at T1 as one of the main independent variables.ResultsHigher CPAQ score was significantly associated with a lower FIQ score at T1, also when adjusting for age, education, work, depression and Fibromyalgianess Score (p<0.01). Lower FIQ score indicate less impact of fibromyalgia on functioning. In addition, two adjusted linear regression models found higher pain acceptance (CPAQ score) at T1 to be associated with lower negative impact of fibromyalgia on function and symptoms (FIQ score) at T2 (p<0.01).ConclusionsHigher pain acceptance is associated with better functional level and less symptoms in fibromyalgia, both cross-sectionally and when measurements are separated in time. Further research should include experimental studies with acceptance-based interventions for this patient group.

Ball Grid Array Thermomechanical Response During Reflow Assembly

1996 ◽  
Vol 118 (4) ◽  
pp. 214-222 ◽  
Author(s):  
T. E. Voth ◽  
T. L. Bergman
Keyword(s):  
Process Model ◽  
Experimental Studies ◽  
Ball Grid Array ◽  
Mechanical Processing ◽  
Processing Conditions ◽  
System Behavior ◽  
Reflow Soldering ◽  
Thermomechanical Response ◽  
Model Predictions ◽  
Representative System

The thermomechanical response of ball-grid array assemblies during reflow soldering is considered here. Experiments are performed to investigate the thermomechanical response of a representative system and the results are used to validate a numerical model of system behavior. The conclusions drawn from the experimental studies are used to guide development of a process model capable of describing more realistic BGA soldering scenarios. Process model predictions illustrate the system’s thermomechanical response to thermal and mechanical processing conditions, as well as component properties. High thermal conductivity assemblies show the greatest sensitivity to mechanical loading conditions.

scholarly journals Characterization of pendrin in urinary extracellular vesicles in a rat model of aldosterone excess and in human primary aldosteronism

2021 ◽  
Author(s):  
Fumika Ochiai-Homma ◽  
Emiko Kuribayashi-Okuma ◽  
Yuya Tsurutani ◽  
Kenichi Ishizawa ◽  
Wataru Fujii ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Rat Model ◽  
Primary Aldosteronism ◽  
Experimental Studies ◽  
Concomitant Administration ◽  
Therapeutic Interventions ◽  
Cross Sectional ◽  
Quantitative Changes ◽  
Highly Correlated ◽  
Sectional Analysis

AbstractPendrin is a Cl−/HCO3− exchanger selectively present in the intercalated cells of the kidney. Although experimental studies have demonstrated that pendrin regulates blood pressure downstream of the renin-angiotensin-aldosterone system, its role in human hypertension remains unclear. Here, we analyzed the quantitative changes in pendrin in urinary extracellular vesicles (uEVs) isolated from a total of 30 patients with primary aldosteronism (PA) and from a rat model of aldosterone excess. Western blot analysis revealed that pendrin is present in dimeric and monomeric forms in uEVs in humans and rats. In a rodent model that received continuous infusion of aldosterone with or without concomitant administration of the selective mineralocorticoid receptor (MR) antagonist esaxerenone, pendrin levels in uEVs, as well as those of epithelial Na+ channel (ENaC) and Na-Cl-cotransporter (NCC), were highly correlated with renal abundance. In patients with PA, pendrin levels in uEVs were reduced by 49% from baseline by adrenalectomy or pharmacological MR blockade. Correlation analysis revealed that the magnitude of pendrin reduction after treatment significantly correlated with the baseline aldosterone-renin ratio (ARR). Finally, a cross-sectional analysis of patients with PA confirmed a significant correlation between the ARR and pendrin levels in uEVs. These data are consistent with experimental studies showing the role of pendrin in aldosterone excess and suggest that pendrin abundance is attenuated by therapeutic interventions in human PA. Our study also indicates that pendrin analysis in uEVs, along with other proteins, can be useful to understand the pathophysiology of hypertensive disorders.

Numerical Modeling and Experimental Studies of the Operational Parameters of the Earth-To-Air Heat Exchanger of the Geothermal Ventilation System

2021 ◽  
Vol 23 ◽  
pp. 42-64
Author(s):  
Boris Basok ◽  
Ihor Bozhko ◽  
Maryna Novitska ◽  
Aleksandr Nedbailo ◽  
Myroslav Tkachenko
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Ventilation System ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Operational Parameters ◽  
Cross Sectional ◽  
Distinctive Features ◽  
Sectional Shape ◽  
Experimental Bench

This article is devoted to the analysis of the heat engineering characteristics of the operation of an Earth-to-Air Heat Exchanger, EAHE, with a circular cross-sectional shape, which is a component of the geothermal ventilation system. The authors analyzed literature sources devoted to the research of heat exchangers of the soil-air type of various designs and for working conditions in various soils. Much attention is paid to the issues of modeling the operation of such heat exchangers and the distinctive features of each of these models. Also important are the results of experimental studies carried out on our own experimental bench and with the help of which the numerical model was validated. The results of these studies are the basis for the development of a method for determining the optimal diameter of an EAHE under operating conditions for soil in Kyiv, Ukraine.

scholarly journals A combined model for pseudo-rapidity distributions in Cu–Cu collisions at BNL-RHIC energies

2016 ◽  
Vol 25 (04) ◽  
pp. 1650025 ◽  
Author(s):  
Z. J. Jiang ◽  
J. Wang ◽  
Y. Huang
Keyword(s):  
Experimental Data ◽  
Proper Time ◽  
Charged Particles ◽  
Dense Matter ◽  
Rapidity Distribution ◽  
Experimental Measurements ◽  
Combined Model ◽  
Model Predictions ◽  
Phobos Collaboration ◽  
Rapidity Distributions

The charged particles produced in nucleus–nucleus collisions come from leading particles and those frozen out from the hot and dense matter created in collisions. The leading particles are conventionally supposed having Gaussian rapidity distributions normalized to the number of participants. The hot and dense matter is assumed to expand according to the unified hydrodynamics, a hydro model which unifies the features of Landau and Hwa–Bjorken model, and freeze out into charged particles from a time-like hypersurface with a proper time of [Formula: see text]. The rapidity distribution of this part of charged particles can be derived analytically. The combined contribution from both leading particles and unified hydrodynamics is then compared against the experimental data performed by BNL-RHIC-PHOBOS Collaboration in different centrality Cu–Cu collisions at [Formula: see text] and 62.4[Formula: see text]GeV, respectively. The model predictions are consistent with experimental measurements.

Simulation of Spouted Bed Using a Eulerian Multiphase Model

2005 ◽  
Vol 498-499 ◽  
pp. 270-277 ◽  
Author(s):  
Claudio Roberto Duarte ◽  
Valéria V. Murata ◽  
Marcos A.S. Barrozo
Keyword(s):  
Control Volume ◽  
Flow Behavior ◽  
Cfd Modeling ◽  
Gas Flows ◽  
Present Calculation ◽  
Multiphase Model ◽  
Spouted Bed ◽  
Particle Coating ◽  
Spouted Beds ◽  
Good Agreement

Spouted bed systems have emerged as very efficient fluid-particle contactors and find many applications in the chemical and biochemical industry. Some important applications of spouted beds include coal combustion, biochemical reactions, drying of solids, drying of solutions and suspensions, granulation, blending, grinding, and particle coating. An extensive overview can be found in Mathur and Epstein[1]. The pattern of solid and gas flows in a spouted bed was numerically simulated using a CFD modeling technique. The Eulerian-Eulerian multifluid modeling approach was applied to predict gas-solid flow behavior. A commercially available, control-volume-based code FLUENT 6.1 was chosen to carry out the computer simulations. In order to reduce computational times and required system resources, the 2D axisymmetric segregated solver was chosen. The typical flow pattern of the spouted bed was obtained in the present calculation. The simulated velocity and voidage profiles presented a good agreement qualitative and quantitative with the experimental results obtained by He et al. [4].

scholarly journals Do employees participate in workplace HIV testing just to win a lottery prize? A quantitative study

2016 ◽  
Vol 15 ◽  
Author(s):  
Martin Weihs ◽  
Anna Meyer-Weitz
Keyword(s):  
Hiv Testing ◽  
Experimental Studies ◽  
Hiv And Aids ◽  
Chi Square ◽  
Cross Sectional ◽  
Small Effect Size ◽  
Hiv Counselling And Testing ◽  
Quasi Experimental ◽  
Managerial Implications ◽  
Permanent Workers

Orientation: To encourage workers to participate in workplace HIV testing, some SouthAfrican automotive companies use lotteries. However, there is a lack of empirical evidence on how lottery incentives may influence employees’ workplace HIV counselling and testing behaviour.Research purpose: Determine whether workers intend to test for HIV only to win a lottery prize.Motivation for the study: The positive and also negative influences of lotteries on workers’ HIV testing behaviour need to be understood to avoid undue coercion in workplace HIV testing participation.Research design, approach and method: Post-test only quasi-experimental studies were conducted the day HIV testing and lotteries were announced to staff in four companies using a cross-sectional, self-administered survey that measured workers’ workplace HIV testing behaviour intentions. Intention to participate in workplace HIV counselling and testing was used as the main outcome of respondents’ behaviour and investigated via the statement: ‘If the company would organise its on-site Wellness Day tomorrow, I would go testing for HIV tomorrow’. In a first setting, two companies’ workers had to test for HIV to be entered in the lottery (n = 198). In the second setting, two other companies’ workers did not have to test to be entered in the lottery (n = 316). Chi-square tests were conducted to measure significant differences between the two conditions distinguishing between permanent and non-permanent staff.Main findings: No significant association was found between behaviour intention in the two settings for permanent workers’ workplace HIV testing intention ( χ2 = 1.145, p = 0.285, phi = -0.097). However, a significant association with a small effect size was found for non-permanent workers ( χ2 = 8.04, p = 0.005, phi = -0.279).Practical/managerial implications: Results show that lotteries to encourage workplace HIV testing are very likely to help workers ‘do the right thing’ and unlikely to have a coercive effect if all staff attending HIV testing has participated in standardised HIV and AIDS workplace programme activities and is informed about the consequences of testing positive.Contribution: A better understanding of how lotteries influence workplace HIV testing among workers of different work status and informed related recommendations.

scholarly journals Sodium Sensitivity, Sodium Resistance, and Incidence of Hypertension

Hypertension ◽  
2021 ◽  
Author(s):  
Jiang He ◽  
Jian-Feng Huang ◽  
Changwei Li ◽  
Jing Chen ◽  
Xiangfeng Lu ◽  
...  
Keyword(s):  
Sodium Intake ◽  
Experimental Studies ◽  
Dietary Sodium ◽  
Cross Sectional ◽  
Incident Hypertension ◽  
High Sodium ◽  
Sodium Sensitivity ◽  
Sodium Diet ◽  
Low Sodium ◽  
Increased Risk

Cross-sectional studies have reported that high sodium sensitivity is more common among individuals with hypertension. Experimental studies have also reported various animal models with sodium-resistant hypertension. It is unknown, however, whether sodium sensitivity and resistance precede the development of hypertension. We conducted a feeding study, including a 7-day low-sodium diet (1180 mg/day) followed by a 7-day high-sodium diet (7081 mg/day), among 1718 Chinese adults with blood pressure (BP) <140/90 mm Hg. We longitudinally followed them over an average of 7.4 years. Three BP measurements and 24-hour urinary sodium excretion were obtained on each of 3 days during baseline observation, low-sodium and high-sodium interventions, and 2 follow-up studies. Three trajectories of BP responses to dietary sodium intake were identified using latent trajectory analysis. Mean (SD) changes in systolic BP were −13.7 (5.5), −4.9 (3.0), and 2.4 (3.0) mm Hg during the low-sodium intervention and 11.2 (5.3), 4.4 (4.1), and −0.2 (4.1) mm Hg during the high-sodium intervention ( P <0.001 for group differences) in high sodium-sensitive, moderate sodium-sensitive, and sodium-resistant groups, respectively. Compared with individuals with moderate sodium sensitivity, multiple-adjusted odds ratios (95% CIs) for incident hypertension were 1.43 (1.03–1.98) for those with high sodium sensitivity and 1.43 (1.03–1.99) for those with sodium resistance ( P =0.006 for nonlinear trend). Furthermore, a J-shaped association between systolic BP responses to sodium intake and incident hypertension was identified ( P <0.001). Similar results were observed for diastolic BP. Our study indicates that individuals with either high sodium sensitivity or sodium resistance are at an increased risk for developing hypertension.

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