Numerical heat flow visualization analysis on enhanced thermal processing for various shapes of containers during thermal convection

2019 ◽  
Vol 30 (7) ◽  
pp. 3535-3583 ◽  
Author(s):  
Leo Lukose ◽  
Tanmay Basak
Keyword(s):  
Finite Element ◽  
Heat Flow ◽  
Flow Visualization ◽  
Thermal Processing ◽  
Bottom Wall ◽  
Heat Distribution ◽  
Content Type ◽  
Class 1

Purpose The purpose of this paper is to study thermal (natural) convection in nine different containers involving the same area (area= 1 sq. unit) and identical heat input at the bottom wall (isothermal/sinusoidal heating). Containers are categorized into three classes based on geometric configurations [Class 1 (square, tilted square and parallelogram), Class 2 (trapezoidal type 1, trapezoidal type 2 and triangle) and Class 3 (convex, concave and triangle with curved hypotenuse)]. Design/methodology/approach The governing equations are solved by using the Galerkin finite element method for various processing fluids (Pr = 0.025 and 155) and Rayleigh numbers (103 ≤ Ra ≤ 105) involving nine different containers. Finite element-based heat flow visualization via heatlines has been adopted to study heat distribution at various sections. Average Nusselt number at the bottom wall ( Nub¯) and spatially average temperature (θ^) have also been calculated based on finite element basis functions. Findings Based on enhanced heating criteria (higher Nub¯ and higher θ^), the containers are preferred as follows, Class 1: square and parallelogram, Class 2: trapezoidal type 1 and trapezoidal type 2 and Class 3: convex (higher θ^) and concave (higher Nub¯). Practical implications The comparison of heat flow distributions and isotherms in nine containers gives a clear perspective for choosing appropriate containers at various process parameters (Pr and Ra). The results for current work may be useful to obtain enhancement of the thermal processing rate in various process industries. Originality/value Heatlines provide a complete understanding of heat flow path and heat distribution within nine containers. Various cold zones and thermal mixing zones have been highlighted and these zones are found to be altered with various shapes of containers. The importance of containers with curved walls for enhanced thermal processing rate is clearly established.

Can the shape influence entropy generation for thermal convection of identical fluid mass with identical heating? A finite element introspection

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Leo Lukose ◽  
Tanmay Basak
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Or Efficiency ◽  
Content Type ◽  
Entropy Generation Minimization ◽  
Class 1 ◽  
Curved Walls

Purpose This paper aims to investigate the role of shapes of containers (nine different containers) on entropy generation minimization involving identical cross-sectional area (1 sq. unit) in the presence of identical heating (isothermal). The nine containers are categorized into three classes based on their geometric similarities (Class 1: square, tilted square and parallelogram; Class 2: trapezoidal type 1, trapezoidal type 2 and triangular; Class 3: convex, concave and curved triangular). Design/methodology/approach Galerkin finite element method is used to solve the governing equations for a representative fluid (engine oil: Pr = 155) at Ra = 103–105. In addition, finite element method is used to solve the streamfunction equation and evaluate the entropy generation terms (Sψ and Sθ). Average Nusselt number ( Nub¯) and average dimensionless spatial temperature ( θ^) are also evaluated via the finite element basis sets. Findings Based on larger Nub¯, larger θ^ and optimal Stotal values, containers from each class are preferred as follows: Class 1: parallelogrammic and square, Class 2: trapezoidal type 1 and Class 3: convex (larger θ^, optimum Stotal) and concave (larger Nub¯). Containers with curved walls lead to enhance the thermal performance or efficiency of convection processes. Practical implications Comparison of entropy generation, intensity of thermal mixing ( θ^) and average heat transfer rate give a clear picture for choosing the appropriate containers for processing of fluids at various ranges of Ra. The results based on this study may be useful to select a container (belonging to a specific class or containers with curved or plane walls), which can give optimal thermal performance from the given heat input, thereby leading to energy savings. Originality/value This study depicts that entropy generation associated with the convection process can be reduced via altering the shapes of containers to improve the thermal performance or efficiency for processing of identical mass with identical heat input. The comparative study of nine containers elucidates that the values of local maxima of Sψ (Sψ,max), Sθ (Sθ,max) and magnitude of Stotal vary with change in shapes of the containers (Classes 1–3) at fixed Pr and Ra. Such a comparative study based on entropy generation minimization on optimal heating during convection of fluid is yet to appear in the literature. The outcome of this study depicts that containers with curved walls are instrumental to optimize entropy generation with reasonable thermal processing rates.

Heatlines visualization of convective heat flow during differential heating of porous enclosures with concave/convex side walls

2018 ◽  
Vol 28 (7) ◽  
pp. 1506-1538 ◽  
Author(s):  
Pratibha Biswal ◽  
Tanmay Basak
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Porous Media ◽  
Natural Convection ◽  
Heat Flow ◽  
Flow Visualization ◽  
Convex Side ◽  
Content Type ◽  
Side Walls ◽  
Element Method

Purpose This paper is aimed to study natural convection in enclosures with curved (concave and convex) side walls for porous media via the heatline-based heat flow visualization approach. Design/methodology/approach The numerical scheme involving the Galerkin finite element method is used to solve the governing equations for several Prandtl numbers (Prm) and Darcy numbers (Dam) at Rayleigh number, Ram = 106, involving various wall curvatures. Finite element method is advantageous for curved domain, as the biquadratic basis functions can be used for adaptive automated mesh generation. Findings Smooth end-to-end heatlines are seen at the low Dam involving all the cases. At the high Dam, the intense heatline cells are seen for the Cases 1-2 (concave) and Cases 1-3 (convex). Overall, the Case 1 (concave) offers the largest average Nusselt number ( Nur¯) at the low Dam for all Prm. At the high Dam, Nur¯ for the Case 1 (concave) is the largest involving the low Prm, whereas Nur¯ is the largest for Case 1 (convex) involving the high Prm. Practical implications Thermal management for flow systems involving curved surfaces which are encountered in various practical applications may be complicated. The results of the current work may be useful for the material processing, thermal storage and solar heating applications Originality/value The heatline approach accompanied by energy flux vectors is used for the first time for the efficient heat flow visualization during natural convection involving porous media in the curved walled enclosures involving various wall curvatures.

scholarly journals Novel Functions for Glycosyltransferases Jhp0562 and GalT in Lewis Antigen Synthesis and Variation in Helicobacter pylori

2012 ◽  
Vol 80 (4) ◽  
pp. 1593-1605 ◽  
Author(s):  
Mary Ann Pohl ◽  
Sabine Kienesberger ◽  
Martin J. Blaser
Keyword(s):  
Helicobacter Pylori ◽  
Wild Type ◽  
Sequence Analyses ◽  
Upstream Gene ◽  
Content Type ◽  
Lewis Antigen ◽  
Mutant Strains ◽  
H Pylori

ABSTRACTLewis (Le) antigens are fucosylated oligosaccharides present in theHelicobacter pylorilipopolysaccharide. Expression of these antigens is believed to be important forH. pyloricolonization, since Le antigens also are expressed on the gastric epithelia in humans. A galactosyltransferase encoded by β-(1,3)galTis essential for production of type 1 (Leaand Leb) antigens. The upstream genejhp0562, which is present in many but not allH. pyloristrains, is homologous to β-(1,3)galTbut is of unknown function. BecauseH. pyloridemonstrates extensive intragenomic recombination, we hypothesized that these two genes could undergo DNA rearrangement. A PCR screen and subsequent sequence analyses revealed that the two genes can recombine at both the 5′ and 3′ ends. Chimeric β-(1,3)galT-like alleles can restore function in a β-(1,3)galTnull mutant, but neither native nor recombinantjhp0562can. Mutagenesis ofjhp0562revealed that it is essential for synthesis of both type 1 and type 2 Le antigens. Transcriptional analyses of both loci showed β-(1,3)galTexpression in all wild-type (WT) and mutant strains tested, whereasjhp0562was not expressed injhp0562null mutants, as expected. Sincejhp0562unexpectedly displayed functions in both type 1 and type 2 Le synthesis, we asked whethergalT, part of the type 2 synthesis pathway, had analogous functions in type 1 synthesis. Mutagenesis and complementation analysis confirmed thatgalTis essential for Lebproduction. In total, these results demonstrate thatgalTandjhp0562have functions that cross the expected Le synthesis pathways and thatjhp0562provides a substrate for intragenomic recombination to generate diverse Le synthesis enzymes.

Numerical Visualization of Heat Flow and Thermal Mixing in Various Differentially Heated Square Cavities Using Bejan’s Heatlines

2011 ◽  
Author(s):  
Ram Satish Kaluri ◽  
Tanmay Basak
Keyword(s):  
Heat Flow ◽  
Bottom Wall ◽  
Temperature Fields ◽  
Heat Distribution ◽  
Heat Sources ◽  
Large Area ◽  
Thermal Mixing ◽  
Uniform Heat ◽  
High Heat Transfer ◽  
Lower Corner

A comprehensive analysis of heat distribution and thermal mixing in steady laminar natural convective flow in discretely heated square cavities has been carried out via Bejan’s heatlines. Heatlines are analogous to streamlines and heat energy flow may be visualized by heatlines similar to streamlines which display fluid flow. The trajectories of heatlines indicate direction and magnitude of heat flow and zones of high heat transfer. The heatline approach is implemented to study heat flow in the following three different square cavities which are filled with water (Pr = 7): (1) uniformly heated bottom wall (2) distributed heating with heat sources present on central portions of the walls and (3) multiple heat sources on the walls of the cavity. Top wall is maintained adiabatic in all the cases. Galerkin finite element method with penalty parameter has been used to solve non-linear coupled partial differential equations for flow and temperature fields over a range of Rayleigh numbers (Ra = 103–105). The Galerkin method is further employed to solve the Poisson equation for streamfunctions and heatfunctions. Finite discontinuity exists at the junction of hot and cold walls leading to mathematical singularity. Solution of heatfunction for such type of situation demands implementation of non-homogeneous Dirichlet conditions. Heatlines illustrate that in uniformly heated bottom wall case, the heat from the bottom wall is not adequately distributed to the lower portion of side walls which leads to low temperature in those regions (case 1). In order to improve the heat distribution, the uniform heat sources is divided into three parts and are applied along the central regimes of the walls (case 2). It is observed that, heat distribution and thermal mixing in the cavity is significantly enhanced. However, the lower corner portions are still retained cold. In case 3, multiple heat sources are placed along the walls of the cavity along with heat sources at lower corner regions of the cavity. Heatlines indicate that, the temperature at the core is reduced compared to case 2, but uniform heat distribution results in uniformity of temperature across large area of cavity.

Gene expression profiling identifies two distinct papillary renal cell carcinoma (RCC) subgroups of contrasting prognosis

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 4503-4503
Author(s):  
B. T. Teh ◽  
X. J. Yang ◽  
M. Tan ◽  
H. L. Kim ◽  
W. Stadler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Renal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Renal Cell ◽  
Papillary Renal Cell Carcinoma ◽  
Comparative Genomic ◽  
Low Grade ◽  
Class 1

4503 Background: Despite the moderate incidence of papillary renal cell carcinoma (PRCC), there is a disproportionately limited understanding of its underlying genetic programs. There is no effective therapy for metastatic PRCC, and patients are often excluded from kidney cancer trials. A morphological classification of PRCC into Type 1 and Type 2 tumors has been recently proposed, but its biological relevance remains uncertain. Methods: We studied the gene expression profiles of 34 cases of PRCC using Affymetrix HGU133 Plus 2.0 arrays (54,675 probe sets) using both unsupervised and supervised analysis. Comparative genomic microarray analysis (CGMA) was used to infer cytogenetic aberrations, and pathways were ranked with a curated database. Expression of selected genes was validated by immunohistochemistry in 34 samples, with 15 independent tumors. Results: We identified two highly distinct molecular PRCC subclasses with morphologic correlation. The first class, with excellent survival, corresponded to three histological subtypes: Type 1, low-grade Type 2 and mixed Type 1/low-grade Type 2 tumors. The second class, with poor survival, corresponded to high-grade Type 2 tumors (n = 11). Dysregulation of G1/S and G2/M checkpoint genes were found in Class 1 and Class 2 tumors respectively, alongside characteristic chromosomal aberrations. We identified a 7-transcript predictor that classified samples on cross-validation with 97% accuracy. Immunohistochemistry confirmed high expression of cytokeratin 7 in Class 1 tumors, and of topoisomerase IIα in Class 2 tumors. Conclusions: We report two molecular subclasses of PRCC, which are biologically and clinically distinct, which may be readily distinguished in a clinical setting. This may also have therapeutic implications. No significant financial relationships to disclose.

An interval type-2 fuzzy ANP approach to evaluate enterprise technological innovation ability

Kybernetes ◽  
2016 ◽  
Vol 45 (9) ◽  
pp. 1486-1500 ◽  
Author(s):  
Tong Wu ◽  
Xinwang Liu
Keyword(s):  
Fuzzy Sets ◽  
Evaluation Model ◽  
Influence Factors ◽  
Content Type ◽  
Fuzzy Anp ◽  
Enterprise Technology ◽  
Innovation Ability ◽  
Interval Type

Purpose The purpose of this paper is to overcome the drawbacks of analytic hierarchy process in solving complex decision-making problems, especially for the evaluation of enterprise technology innovation ability (ETIA). Because interval type-2 fuzzy sets (IT2 FSs) can handle uncertainty linguistic variables in a more flexible and precise way than type-1 fuzzy sets with their second fuzzy membership functions, a fuzzy ANP method with IT2 FSs is proposed to evaluate the ETIA. Design/methodology/approach The criteria of evaluation on ETIA are identified and an evaluation model for ETIA is constructed on the basis of the application analysis of ETIA and theoretical design of ANP. In addition, two different ranking methods of IT2 FSs are applied in processing the relationships between influence factors of ETIA. Findings By using the proposed interval type-2 fuzzy ANP (IT2 FANP) method, the efficiencies of the whole evaluation of ETIA can be measured and the important factors in the ETIA can also be determined. Compared with the type-1 FANP through the ranking results, the proposed IT2 FANP is more reasonable and robust for the evaluation of ETIA. Practical implications The proposed IT2 FANP method is applied on the evaluation of ETIA. With respect to the application, the proposed method can be used to evaluate many more complex problems that contain feedback and circular relationships. Originality/value The proposed IT2 FANP approach can solve the complexities and uncertainties at the same time. Considering the subjective initiative of decision-makers and the feedback between influence factors, the proposed method is more efficient than the existing type-1 approaches in the literature.

Role of heatlines on thermal management during Rayleigh-Bénard heating within enclosures with concave/convex horizontal walls

2017 ◽  
Vol 27 (9) ◽  
pp. 2070-2104 ◽  
Author(s):  
Pratibha Biswal ◽  
Tanmay Basak
Keyword(s):  
Heat Flow ◽  
Flow Visualization ◽  
Numerical Solutions ◽  
Fluid Velocity ◽  
Content Type ◽  
Bénard Convection ◽  
Benard Convection ◽  
First Time ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Purpose This study aims to carry out the analysis of Rayleigh-Bénard convection within enclosures with curved isothermal walls, with the special implication on the heat flow visualization via the heatline approach. Design/methodology/approach The Galerkin finite element method has been used to obtain the numerical solutions in terms of the streamlines (ψ ), heatlines (Π), isotherms (θ), local and average Nusselt number ( Nut¯) for various Rayleigh numbers (103 ≤ Ra ≥ 105), Prandtl numbers (Pr = 0.015 and 7.2) and wall curvatures (concavity/convexity). Findings The presence of the larger fluid velocity within the curved cavities resulted in the larger heat transfer rates and thermal mixing compared to the square cavity. Case 3 (high concavity) exhibits the largest Nut¯ at the low Ra for all Pr. At the high Ra, Nut¯ is the largest for Case 3 (high concavity) at Pr = 0.015, whereas at Pr = 7.2, Nut¯ is the largest for Case 1 (high concavity and convexity). Practical implications The results may be useful for the material processing applications. Originality/value The study of Rayleigh-Bénard convection in cavities with the curved isothermal walls is not carried out till date. The heatline approach is used for the heat flow visualization during Rayleigh-Benard convection within the curved walled enclosures for the first time. Also, the existence of the enhanced fluid and heat circulation cells within the curved walled cavities during Rayleigh-Benard heating is illustrated for the first time.

scholarly journals Mechanical Force System of Double Key Loop With Finite Element Analysis 

2020 ◽  
Author(s):  
Jiali Liu ◽  
Duanqiang Zhang ◽  
Linyu Xu ◽  
Senxin Cai ◽  
Jinquan Guo ◽  
...  
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Vertical Force ◽  
Element Analysis ◽  
Force System ◽  
Anterior Teeth ◽  
Lower Magnitude ◽  
Type 3

Abstract Background: The mechanics of double key loop (DKL) was not well defined and this finite element study was designed to explore its force system.Methods: Simplified 3-dimensional finite element model of single and double key loops with archwire between lateral incisor and second premolar was established in Ansys Workbench. Activation in Type-1 (retraction at distal end), Type-2 (retraction at distal key) and Type-3 (Type-2 plus ligation between keys) were simulated. The vertical force, load/deflection ratio and moment/force ratio of stainless steel and TMA loops were calculated and compared.Results: Double key loop generated about 40% force of single key loop. Type-2 loading of DKL showed higher L/D ratio than in Type-1 loading with similar M/F ratio. Type-3 loading of DKL showed the highest M/F ratio with similar L/D ratio as single key loop. The M/F ratio in Type-3 loading increased with the decrease of retraction force. DKL of TMA produced about 40% of force and moment compared to those of SS in all loading types. When activated at equal distance bellow 1mm, the M/F ratio of SS and TMA DKL with equal preactivation angle were almost the same. Conclusion: M/F ratio on anterior teeth increases with preactivation angle and deactivation of DKL. M/F ratio at certain distance of activation depends mainly on preactivation angle instead of wire material. TMA is recommended as substitute of SS in DKL for lower magnitude of force.

Multi-objective vendor managed inventory system with interval type-2 fuzzy demand and order quantities

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zubair Ashraf ◽  
Mohammad Shahid
Keyword(s):  
Fuzzy Numbers ◽  
Vendor Managed Inventory ◽  
Content Type ◽  
Multi Objective ◽  
Demand Rate ◽  
Order Quantities ◽  
Interval Type ◽  
Pareto Fronts

PurposeThe proposed IT2FMOVMI model intends to concurrently minimize total cost and warehouse space for the single vendor-retailer, multi-item and a consolidated vendor store. Regarding demand and order quantities with the deterministic and type-1 fuzzy numbers, we have also formulated the classic/crisp MOVMI model and type-1 fuzzy MOVMI (T1FMOVMI) model. The suggested solution technique can solve both crisp MOVMI and T1FMOVMI problems. By finding the optimal ordered quantities and backorder levels, the Pareto-fronts are constructed to form the solution sets for the three models.Design/methodology/approachA multi-objective vendor managed inventory (MOVMI) is the most recognized marketing and delivery technique for the service provider and the retail in the supply chain in Industry 4.0. Due to the evolving market conditions, the characteristics of the individual product, the delivery period and the manufacturing costs, the demand rate and order quantity of the MOVMI device are highly unpredictable. In such a scenario, a MOVMI system with a deterministic demand rate and order quantity cannot be designed to estimate the highly unforeseen cost of the problem. This paper introduces a novel interval type-2 fuzzy multi-objective vendor managed inventory (IT2FMOVMI) system, which uses interval type-2 fuzzy numbers (IT2FNs) to represent demand rate and order quantities. As the model is an NP-hard, the well-known meta-heuristic algorithm named NSGA-II (Non-dominated sorted genetic algorithm-II) with EKM (Enhanced Karnink-Mendel) algorithm based solution method has been established.FindingsThe experimental simulations for the five test problems that demonstrated distinct conditions are considered from the real-datasets of SAPCO company. Experimental study concludes that T1FMOVMI and crisp MOVMI schemes are outclassed by IT2FMOVMI model, offering more accurate Pareto-Fronts and efficiency measurement values.Originality/valueUsing fuzzy sets theory, a significant amount of work has been already done in past decades from various points of views to model the MOVMI. However, this is the very first attempt to introduce type-2 fuzzy modelling for the problem to address the realistic implementation of the imprecise parameters.

Family firms, political connections and audit fees: evidence from Malaysian firms

2018 ◽  
Vol 33 (6/7) ◽  
pp. 613-632 ◽  
Author(s):  
Chwee Ming Tee
Keyword(s):  
Family Firms ◽  
Audit Fees ◽  
Emerging Economy ◽  
Political Connections ◽  
Advanced Economy ◽  
Content Type ◽  
Self Selection ◽  
Institutional Feature

Purpose The purpose of this study is to examine the association between family firms and audit fees in an emerging economy setting. As family firms either face Type 1 or Type 2 agency problem, it seeks to gain a better understanding on family firms in an emerging economy such as Malaysia. Additionally, this study introduces political connections to investigate whether it can moderate the association between family firms and audit fees. Political connection is chosen as an important institutional feature because of its many and well-documented politically connected firms and pervasive political patronage system in Malaysia. Design/methodology/approach Based on a dataset of 750 firms or 7,848 firm-year observations from 2002 till 2015, panel regression analysis is used to investigate the research questions. As a robustness test, Heckman’s self-selection model is used to deal with the self-selection problem. Findings The results reveal that family firms are associated with higher audit fees, indicating that Type 2 dominates Type 1 agency problems in Malaysia. This positive relationship is stronger in family firms which are older and have higher family controlling shareholding. Further, the association is exacerbated if it is also connected to the ruling elite. Originality/value This study contributes to the literature by showing that institutional feature such as family firms and political connections can produce different firm outcomes between emerging and advanced economy, particularly in auditing. This study responds to calls for more research on auditing in family firms, particularly in emerging economy.

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