Heat transfer characteristics and entropy generation for wing-shaped-tubes with longitudinal external fins in cross-flow

Sayed Ahmed E. Sayed Ahmed,Osama M. Mesalhy,Mohamed A. Abdelatief 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.6

A numerical study is conducted to clarify heat transfer characteristics, effectiveness and entropy generation for a bundle of wingshaped-tubes attached to Longitudinal fins (LF) at downstream side. The air-side Re a ranged from 1.8 x 10 3 to 9.7 x 10 3 . The fin height (h f ) and fin thickness (δ) have been changed as: (2 mm ≤ h f ≤ 12 mm) and (1.5 mm ≤ δ ≤ 3.5 mm). The analysis of entropy generation is based on the principle of minimizing the rate of total entropy generation that includes the generation of entropy due to heat transfer and friction losses. The temperature field around the wing-shaped-tubes with (LF) is predicted using commercial CFD FLUENT 6.3.26 software package. Correlations of Nu a , St a , and Bejan number (Be), as well as the irreversibility distribution ratio (Φ) in terms of Re a and design parameters for the studied bundle are presented. Results indicated that, installing fins with heights from 2 to 12 mm results in an increase in Nu a from 11 to 36% comparing with that of wing-shaped tubes without fins (NOF). The highest and lowest values of effectiveness (ε) at every value of the considered Re a range are occurred at h f = 6 mm and (NOF), respectively. The wing-shaped-tubes heat exchanger with h f = 6 mm has the highest values of (ε), efficiency index (η) and area goodness factor (G a ) and also the lowest values of Φ and hence the best performance comparing with other arrangements. The minimum values of Φ are occurred at h f = 6 mm. (Be) decreases with increasing Re a for all studied h f . The heat transfer irreversibility predominates for (1800 ≤ Re a ≤ 4200) while the opposite is true for (6950 < Re a ≤ 9700). δ has negligible effect on Nu a and heat transfer irreversibility. Comparisons between the experimental and numerical results of the present study and those, previously, obtained for similar available studies showed good agreements.

Life Span Extension of Caenorhabditis elegans by Novel Pyridoperimidine Derivative

Ahmed A. R. Sayed,Kamal M. El-Shaieb,Aboul-Fetouh E. Mourad 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.1

Zwitterions formed from the addition of triphenylphosphine to dialky acetylene-dicarboxylates attack the nucleus of both 1H-perimidine (1) and 1H-benzo[d]imidazole (9) to form novel pyrido[1,2,3-cd]perimidine and imidazo[4,5,1-ij]quinoline derivatives in moderate yields (64-72%). The biological activity of the products has been studied. Compound 3a was found to extend life span of wild type Caenorhabditis elegans under standard laboratory conditions. Both heat stress and induced chemical stress resistance of wild type C. elegans were improved in a reverse dose-dependent manner due to 3a treatment. In addition, treatment of worms with compound 3a significantly attenuated the formation of advanced glycation end products in a reverse dose-dependent manner.

Analysis and Mitigation of Ground Grid Lightning Potential Rise

Ahmed Taher,Abdelrahman Said,Tamer Eliyan,Abdelsalam Hafez 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.3

Grid design depends mainly on bringing grounding resistance, mesh voltage, and step voltage below tolerable limits when subjected to any ground fault. But, it should be noticed that the grid performance has to be tested when subjected to lightning stroke. The performance of the grid under impulse current diff ers than that of under power–frequency fault. In this paper ATP-EMTP software is used to analyze the performance of the ground grid when subjected to lightning stroke. Different methods are suggested to mitigate the lightning overvoltage, all of these methods depend mainly on modifying the design by adding more conductors or rods at specific places. The case study under consideration is Al-Mostakbal substation 220/22 kV which is located in Al-Mostakbal city, Cairo, Egypt.

Incidence of Listeria in Egyptian Meat and Dairy Samples

Ahmed Abdel-Rhman Ismaiel,Ali El-Sayed Ali,Gamal Enan 한국식품과학회 2014 Food Science and Biotechnology Vol.23 No.1

A total of 180 food samples including meat(raw lean beef, frozen lean beef, and frozen chicken) anddairy products (raw milk, Zabady and Kareesh cheese)were analysed for Listeria. Isolates were differentiatedusing morphological, cultural, and biochemical tests and anAPI-Listeria kit. Zabady cheese was completely free ofListeria. The highest incidence rate (13.33%) was in frozenlean beef. Raw lean beef and milk products showed anincidence rate of 6.67%. The lowest incidence rate (3.33%)was in Kareesh cheese and frozen chicken meat samples. L. monocytogenes showed the lowest incidence rate(0.55%), isolated from one frozen lean beef sample. L. ivanovii and L. grayi showed the highest incidence rate(2.22%), isolated from 4 samples. L. innocua and L. seeligeri were positive in 3 samples (1.67%), and L. welshimeri in 2 samples (1.11%). L. monocytogenes and L. ivanovii were positive for virulence factors (hemolyticproperties, and extracellular enzyme activities).

Economic and Technical Analysis of Cooling System in Gas Turbine

Ahmed El Sayed Hafez,Ko ByungGuk(고병국),Yoon YongBeum(윤용범) 대한전기학회 2020 대한전기학회 학술대회 논문집 Vol.2020 No.10

Centrifugal Impeller Blade Shape Optimization Through Numerical Modeling

Sayed Ahmed Imran Bellary,Abdus Samad 한국유체기계학회 2016 International journal of fluid machinery and syste Vol.9 No.4

Surrogate model based shape optimization methodology to enhance performance of a centrifugal pump has been implemented in this work. Design variables, such as blade number and blade angles defining the pump impeller blade shape were selected and a three-level full factorial design approach was used for efficiency enhancement. A threedimensional simulation using Reynolds-averaged Navier Stokes (RANS) equations for the performance analysis was carried out after designing the geometries of the impellers at the design points. Standard k-ε turbulence model was used for steady incompressible flow simulations. The optimized impeller incurred lower losses by shifting the trailing edge towards the impeller pressure side. It is observed that the surrogates are problem dependent and most accurate surrogate does not deliver the best design always.

Synthesis and Pharmacological Screening for Muscle Relaxant, Anticonvulsant, and Sedative Activities of Certain Organic Compounds Produced by Michael Addition

Said , Makarem M.,Ahmed, Amany A. E.,El-Alfy, Abir T. The Pharmaceutical Society of Korea 2004 Archives of Pharmacal Research Vol.27 No.12

Michael addition of certain nucleophiles on ${\alpha}$ , ${\beta}$-unsaturated ketones 1 led to the formation of adducts 2-7 as well as the reaction of arylidene derivatives with secondary amines afforded the amino compounds 9 and 11. Also, dialkylmalonates were treated with ${\alpha}$-cyano cinnamide to afford 13. On the other hand, double Michael cycloaddition of ethylcyanoacetate or tetrachlorophthalic anhydride to the suitable divinylketone were synthesized to produce 15-17. Selected compounds (13 and 6) were screened for muscle relaxant, anticonvulsant, and sedative activities using established pharmacological models. Their activities were compared with that of phenobarbital sodium taken as standard. Compound 6 was the most potent muscle relaxant while compounds 13a and 13c offered the highest anticonvulsant activity. Meanwhile compound 13c showed the highest potentiation of phenobarbital induced sleep in mice.

ON MULTIVALUED FIXED POINT FOR (α∗, η∗, θ) CONTRACTIONS WITH AN APPLICATION

Ahmed Ali,Saadia Mahideb,Said Beloul 한국전산응용수학회 2021 Journal of Applied and Pure Mathematics Vol.3 No.5

In this paper, we prove the existence of a multivalued fixed point, by combining Geraghty contraction with \theta-contraction and \alpha,\eta-admissible concepts. Some consequences are given in metric spaces endowed with partial order or with graph, also we provide an example and an application to the existence of solutions of a boundary value problem for fractional differential inclusions to demonstrate the usability of our outcomes.

Effectiveness of meta-models for multi-objective optimization of centrifugal impeller

Sayed Ahmed Imran Bellary,Afzal Husain,Abdus Samad 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12

The major issue of multiple fidelity based analysis and optimization of fluid machinery system depends upon the proper constructionof low fidelity model or meta-model. A low fidelity model uses responses obtained from a high fidelity model, and the meta-model isthen used to produce population of solutions required for evolutionary algorithm for multi-objective optimization. The Pareto-optimalfront which shows functional relationships among the multiple objectives can produce erroneous results if the low fidelity models are notwell-constructed. In the present research, response surface approximation and Kriging meta-models were evaluated for their effectivenessfor the application in the turbomachinery design and optimization. A high fidelity model such as CFD technique along with the metamodelswas used to obtain Pareto-optimal front via multi-objective genetic algorithm. A centrifugal impeller has been considered as casestudy to find relationship between two conflicting objectives, viz., hydraulic efficiency and head. Design variables from the impellergeometry have been chosen and the responses of the objective functions were evaluated through CFD analysis. The fidelity of each metamodelhas been discussed in context of their predictions in entire design space in general and near optimal region in particular. Exploitationof the multiple meta-models enhances the quality of multi-objective optimization and provides the information pertaining to fidelityof optimization model. It was observed that the Kriging meta-model was better suited for this type of problem as it involved less approximationerror in the Pareto-optimal front.

Association Assessment among Risk Factors and Breast Cancer in a Low Income Country: Bangladesh

Ahmed, Kawsar,Asaduzzaman, Sayed,Bashar, Mamun Ibn,Hossain, Goljar,Bhuiyan, Touhid Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.17

Background: In the low incoming country Bangladesh, breast cancer is second most common neoplasm and is increasing at an alarming rate among females. Lack of awareness and illiteracy are contributory factors for late presentation and therefore mortality. Purpose: To examine associations of different factors with breast cancer mortality and to raise awareness among the women of society in Bangladesh. Materials and Methods: This descriptive case-control study was conducted on 160 participants from April 2011 till July 2014. Through a valid questionnaire covering personal and family history, data were collected by face to face interview. For analyzing correlations among factors with breast cancer data, binary logistic regression, Pearson's ${\chi}^2$-value, odd ratios and p-value tests were conducted with SPSS version 20. Results: The mean age of the patients was 43.0 ($SD={\pm}11.12$). In ascending order the leading significant factors were hormone therapy (p<0.0000, OR=4.897), abortion (p<0.0001, OR=3.452), early start menarche (p<0.0002, OR=3.500), family history (p<0.0022, OR=3.235), and late menopause (p<0.0093, OR=3.674) with both ${\chi}^2$ test and logistic regression analyses. Non-significant factors were cancer experience, fatty food habits, marital status and taking alcohol. Conclusions: Regarding the investigation of this study, significant and insignificant factor's correlation visualization with breast cancer will be helpful to increase awareness among Bangladeshi women as well as all over the world.