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.

Determining Dimensions of Job Satisfaction among Employees: Evidence from Commercial Bank Industries in Bangladesh

Md. Sayed UDDIN(Md. Sayed UDDIN ),Md. Atikur RAHAMAN(Md. Atikur RAHAMAN ),Wasib Bin LATIF(Wasib Bin LATIF ) 한국유통과학회 2023 The Journal of Asian Finance, Economics and Busine Vol.10 No.2

Since the banking industry relies so heavily on strong customer-staff interactions, measuring employee job satisfaction has become a critical problem. To achieve benefits for both individuals and organizations, it is crucial to foster and ensure employee job satisfaction. The main objective of this study is to determine the influencing factors of employees’ job satisfaction in commercial banks in Bangladesh. This study focused on some significant factors such as employee empowerment, job security, management support, and attractive compensation in an organization. In terms of research purpose, non-probability convenience sampling has been used, and the study is quantitative in nature. For data collection purposes, an online survey questionnaire was prepared based on previously published articles. The targeted population was the bank employees of commercial banks in Bangladesh where the final sample size was n = 200. For analyzing the collected data, SPSS 26.0 version has been used to test the study model and the proposed hypotheses. This study also shows that employee empowerment, job security, management support, and attractive compensation have positive and significant effects on employees’ job satisfaction at the workplace. Finally, this study has offered some extraordinary directions and implications for future research on commercial bank authorities in Bangladesh.

Separation axioms in (L,M)-fuzzy topology (L,M)-fuzzy convexity spaces

Osama Rashed Sayed,EL-Sayed EL-Sanousy,Yaser Hassanein Ragheb Sayed 원광대학교 기초자연과학연구소 2021 ANNALS OF FUZZY MATHEMATICS AND INFORMATICS Vol.21 No.1

In this paper, we dene r-L-fuzzy closed convex sets and r-L-fuzzy closed neighbourhoods in an (L, M)-fuzzy topology (L, M)-fuzzy convexity spaces. Also, r-L-fuzzy neighbourhood separation properties r- L-FNSi were studied where i = f0, 1, 2, 3, 4g. In addition, we also study the invariance or otherwise of these separation properties under subspace and product.

Alleviation of salt stress in  Triticum aestivum by biopriming with  Phanerochaete chrysosporium

Hanan El-Sayed Dief,El-Sayed A. Hashem,Salwa Fawzan,Ashraf S. A. El-Sayed 한국작물학회 2021 Journal of crop science and biotechnology Vol.24 No.1

Wheat is one of the most important cereals, vital basic crop in Egypt, covering approximately 32.6% of the total winter land. However, sensitivity to abiotic stress especially salinity is one the major current hurdles that reduce the global yield of this crop. Plant biopriming with fungi is the recent technology that might alleviate the salt stress eff ect. Thus, the objective of this work was to examine the eff ect of Triticum aestivum grains biopriming with Phanerochaete chrysosporium on the response of wheat to salt stress. From the physiological and biochemical parameters, biopriming of wheat grains with P. chrysosporium significantly alleviates the salt stress and markedly increases the growth parameters, photosynthetic pigments and osmolytes (soluble sugars, soluble protein and proline) contents. In addition, it alleviates the oxidative damage, as indicated by the lower accumulation of malondealdehyde and increasing the activity of antioxidant enzymes; superoxide dismutase, catalase, and ascorbate peroxidase in wheat seedlings. Results indicate the potential of using P. chrysosporium biopriming for reducing the deteriorating eff ects of salinity.

The $\overline\partial$-problem with support conditions and pseudoconvexity of general order in K\"ahler manifolds

Sayed Saber 대한수학회 2016 대한수학회지 Vol.53 No.6

Let $M$ be an $n$-dimensional K\"ahler manifold with positive holomorphic bisectional curvature and let $\Omega\Subset M$ be a pseudoconvex domain of order $n-q$, $1\leq q\leq n$, with $C^{2}$ smooth boundary. Then, we study the (weighted) $\overline\partial$-equation with support conditions in $\Omega$ and the closed range property of $\overline\partial$ on $\Omega$. Applications to the $\overline\partial$-closed extensions from the boundary are given. In particular, for $q=1$, we prove that there exists a number $\ell_{0}>0$ such that the $\overline\partial$-Neumann problem and the Bergman projection are regular in the Sobolev space $W^{\ell}(\Omega)$ for $\ell<\ell_{0}$.

Investigation of cake deposition on various parts of the surface of microfiltration membrane due to fouling

Sayed Siavash Madaeni,Masoud Rahimi,Mahdiah Abolhasani 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.1

The accumulation of deposited layer on membrane surface in cross-flow microfiltration was investigated. This study provides a basis for elucidation of the membrane segments with superior tendency for cake deposition due to fouling. A commercially available GVWP membrane was fouled with a colored (blue indigo suspension in water) feed. The deposition pattern or fouling tendency was obtained using a digital camera, scanning electron microscope (SEM)and image analysis. The effects of feed concentration, transmembrane pressure and cross-flow velocity on cake deposition were investigated. In the early stages of the filtration trials, cake deposition was increased from the commencement portion (feed inlet) towards the furthermost part (concentrate outlet) of the membrane surface. However, at the completion of filtration, no pronounced difference was realized between cake deposition in the median and end parts of the membrane. Computational fluid dynamics (CFD) modeling of the membrane was carried out to predict the fouling behavior in various segments of the membrane at different operating conditions. The results of CFD modeling are in acceptable agreement with the experimental data. Accomplishment of the membrane sections with higher tendency for accumulation of foulants may provide a basis for manipulation of conditions to diminish the buildup of fouling deposition in the proposed segments. This results in lower cake deposition on vital parts to minimize the overall fouling.

GLOBAL SOLUTIONS FOR THE a-PROBLEM ON NON PSEUDOCONVEX DOMAINS IN STEIN MANIFOLDS

Sayed Saber 대한수학회 2017 대한수학회지 Vol.54 No.6

In this paper, we prove basic a priori estimate for the $\overline\partial$-Neumann problem on an annulus between two pseudoconvex submanifolds of a Stein manifold. As a corollary of the result, we obtain the global regularity for the $\overline\partial$-problem on the annulus. This is a manifold version of the previous results on pseudoconvex domains.

The effect of microfinance on women’s empowerment : Evidence from Malaysia

Sayed Samer Ali AL-SHAMI,Muhammad M. RAZALI,Izaidin MAJID,Ahmed ROZELAN,Nurulizwa RASHID 이화여자대학교 아시아여성학센터 2016 Asian Journal of Women's Studies(AJWS) Vol.22 No.3

Microfinance is widely known as a financial development tool for those deprived of access to financial services, especially women. However, the literature provides conflicting evidence and shows that women’s empowerment may not, or may only be partially achieved through microcredit, especially in Muslim societies. This study seeks to scrutinize the effect of Amanah Ikhtiar Malaysia (AIM), a microcredit institution, on Malay Muslim women in an urban area. A quasi-experimental method was used to conduct a cross sectional survey of 500 old and new clients. Informal semi-structured interviews were conducted with 20 current clients who had received microcredit two years earlier. The findings show that AIM microcredit empowered the women and enhanced gender equality. It enabled women to access financial capital, form their micro- and smallbusinesses and obtain an income which helped them to contribute to household expenditure. Even though the effect of microcredit was partial, it provided them bargaining power for decision-making and controlling of resources and enhanced their self-esteem in their households and communities. Pembiayaan mikro secara meluasnya dikenali sebagai kaedah membangunkan mereka yang tidak diberi peluang akses perkhidmatan kewangan lain, khasnya di kalangan golongan wanita. Walau bagaimanapun, literatur kajian lampau telah mengemukakan bukti yang bercanggah di mana pembiayaan mikro kepada golongan wanita terutamanya mereka dalam masyarakat Islam mungkin tidak langsung atau mungkin sebahagiannya sahaja memberi kesan terhadap kejayaan mereka. Kajian ini bertujuan untuk meneliti kesan Amanah Ikhtiar Malaysia (AIM) iaitu sebuah institusi pembiayaan mikro, di kalangan wanita Melayu Islam di kawasan bandar. Satu kaedah kuasieksperimen telah digunakan untuk menjalankan kajian terhadap 500 pelanggan lama dan baru pembiayaan mikro. Temubual informal separa berstruktur telah dijalankan bersama 20 pelanggan yang sedang menerima pembiayaan mikro dalam tempoh dua tahun sebelumnya. Hasil kajian menunjukkan bahawa pembiayaan mikro AIM menjadikan wanita bertambah berjaya dan dapat menyumbang terhadap kesamarataan antara gender. Ia membolehkan mereka memperolehi modal, membentuk perniagaan mikro atau kecil dan seterusnya memperolehi pendapatan yang dapat membantu mereka untuk menyumbang kepada perbelanjaan isi rumah. Walaupun kesan pembiayaan mikro ini menyumbang kepada sebahagian sahaja peningkatan ini, namun ia dapat menyediakan mereka kuasa tawar-menawar untuk membuat keputusan, kawalan ke atas sumber dan meningkatkan keyakinan diri golongan ini.

PWM Control Techniques for Single-Phase Multilevel Inverter Based Controlled DC Cells

Sayed, Mahmoud A.,Ahmed, Mahrous,Elsheikh, Maha G.,Orabi, Mohamed The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

This paper presents a single-phase five-level inverter controlled by two novel pulse width modulation (PWM) switching techniques. The proposed PWM techniques are designed based on minimum switching power loss and minimum total harmonic distortion (THD). In a single-phase five-level inverter employing six switches, the first proposed PWM technique requires four switches to operate at switching frequency and two other switches to operate at line frequency. The second proposed PWM technique requires only two switches to operate at switching frequency and the rest of the switches to operate at line frequency. Compared with conventional PWM techniques for single-phase five-level inverters, the proposed PWM techniques offer high efficiency and low harmonic components in the output voltage. The validity of the proposed PWM switching techniques in controlling single-phase five-level inverters to regulate load voltage is verified experimentally using a 100 V, 500 W laboratory prototype controlled by dspace 1103.

On nonlinear vibration behavior of piezo-magnetic doubly-curved nanoshells

Sayed Sajad Mirjavadi,Hassan Bayani,Navid Khoshtinat,Masoud Forsat,Mohammad Reza Barati,A.M.S. Hamouda 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.5

In this paper, nonlinear vibration behaviors of multi-phase Magneto-Electro-Elastic (MEE) doubly-curved nanoshells have been studied employing Jacobi elliptic function method. The doubly-curved nanoshell has been modeled by using nonlocal elasticity and classic shell theory. An exact estimation of nonlinear vibrational behavior of smart doubly-curved nanoshell has been obtained via Jacobi elliptic function method. This method can incorporate the influences of higher order harmonics leading to an exact estimation of nonlinear vibration frequency. It will be indicated that nonlinear vibrational frequency of doubly-curved nanoshell relies on nonlocal effect, material composition, curvature radius, center deflection and electro-magnetic field.