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RISS 인기검색어
- 검색키워드
- 저자 : Ahmed Hesham A. (검색결과 4 건)
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Effect of light intensity and air velocity on the thermal exchange of indoor-cultured lettuce
Ahmed Hesham A.,Li Yangmei,Shao Lingzhi,Tong Yu-xin 한국원예학회 2022 Horticulture, Environment, and Biotechnology Vol.63 No.3
Heat and moisture transfer have a substantial influence on plant photosynthesis and productivity. Therefore, this study investigated the combined effect of light intensity (100, 200, and 300 μmol m−2 s−1) and air velocity (0.25, 0.50, and 0.75 m s−1) on the sensible heat flux (Sh), convection regime (CR), and latent heat flux (Lh) of lettuce plants grown in a plant factory with artificial light. The growth, photosynthetic rate, and occurrence of tipburn in lettuce plants were also evaluated. The effect of light intensity and air velocity on the thermal exchange of indoor-cultured lettuce was achieved through their combined effect on conductance to heat and mass transfer. Stomatal conductance was found to be strongly correlated with light intensity, with a correlation coefficient of 73%. The boundary layer conductance was highly correlated with air velocity, with a correlation coefficient of 96%. Accordingly, the Sh and Lh increased by 41.0% and 46.9%, respectively, with an increase in light intensity from 100 to 300 μmol m−2 s−1, and by 33.2% and 30.4%, respectively, with an increase in air velocity from 0.25 to 0.75 m s−1. Air velocity had a greater impact on CR, and forced convection was dominant between lettuce plants and the surrounding air. During the dark period, a decrease in stomatal conductance was accompanied by a decrease in Lh, particularly as air velocity increased. The photosynthetic rate and fresh weight of lettuce plants were strongly correlated with light intensity, and increased by 60.9% and 54.7%, respectively, as light intensity increased from 100 to 300 μmol m−2 s−1. However, the occurrence of tipburn in lettuce plants was significantly related to light intensity, and the highest number of lettuce leaves injured with tipburn of 5 leaves/plant was observed at a light intensity of 300 μmol m−2 s−1. When air velocity increased from 0.25 to 0.75 m s−1, the occurrence of tipburn decreased by 87.3%. Our results reveal that there was an obvious interaction between light intensity and air velocity on the thermal exchange, growth, and occurrence of tipburn in indoor-cultured lettuce. This study provides valuable insights into the combinational regulation of light intensity and air velocity for improving the growth and marketability of indoor-cultured lettuce.
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Hesham Mohamed Gharieb,Mo’mena Ahmad A Awad-Allah,Anas Adel Ahmed,Ihab Saad Othman 대한안과학회 2021 Korean Journal of Ophthalmology Vol.35 No.2
Purpose: To compare single-step transepithelial photorefractive keratectomy (TPRK) to conventional alcohol assisted epithelialremoval then photorefractive keratectomy (AAPRK) regarding pain, epithelial healing, visual acuity, corneal haze measuredsubjectively and objectively, higher order aberrations changes, contrast sensitivity and vector analysis of astigmatic correctionwith one year follow-up. Methods: A prospective double-blind randomized study of 29 subjects (58 eyes) who underwent myopic aberration-freelaser correction by smart pulse technology using Schwind Amaris 1050 Hz with 1-year follow-up. Right eye was randomlytreated by AAPRK or TPRK. Postoperative assessment was performed on day 1 and 3, at 1st week, and 1st, 3rd, 6th, and 12thmonths. Patients were assessed for pain, epithelial healing, visual acuity, corneal haze, astigmatic correction, higher order aberrationsand contrast sensitivity. Results: Epithelial healing was complete by the 3rd day in 62.1% of AAPRK eyes and in 89.7% of TPRK eyes. First day postoperativepain was higher in TPRK group (p = 0.0134). The decimal uncorrected visual acuity at 12 months was 1.47 ± 0.39 and1.57 ± 0.38 in the AAPRK and TPRK groups respectively (p = 0.3719). Post-photorefractive keratectomy haze reached a finallevel of 0.04 ± 0.14 and 0.02 ± 0.1 in AAPRK and TPRK groups respectively (p = 0.5607). Contrast sensitivity was comparable inlow and high frequency cycles per degree. Vector analysis of astigmatic correction showed correction index at one year of 0.99and 1.05 for AAPRK and TPRK groups respectively. Conclusions: Alcohol assisted and transepithelial photorefractive keratectomy have comparable results regarding safety andefficacy.
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Applications of Clustering Models in Offshore Drilling for Crude Oil and Natural Gas
Hesham K. Alfares,Katta G. Murty,Ahmed A. AlSaaty 대한산업공학회 2019 Industrial Engineeering & Management Systems Vol.18 No.1
An important problem in offshore drilling for crude oil and natural gas is to find the optimum allocation of wells to drill, to multiple drilling rigs; to minimize the total cost of drilling. In practice, the drilling cost of each well is a function of both the distance to the drilling rig and the rig’s individual cost. In this paper, we consider this problem and present both an exact and a heuristic algorithm under two cases. Case 1 considers the problem in which rig locations are given, while Case 2 considers the problem in which rig locations are to be determined optimally. The new models and algorithms are unique because each drilling rig has a different cost rate per mile. Using data from an offshore oil field under development, the new models are used to minimize the total drilling cost for the two cases. In addition, a computational study is conducted, confirming the effectiveness of the proposed heuristic algorithm.
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Barakat Mohamed,Donkol Ahmed,Hamed Hesham F. A.,Salama Gerges M. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4
This paper presents a new optimization tool-based population parameter called Harris hawks optimizer (HHO) and its application study to fi ne-tune the gains of well-designed proportional-derivative proportional-integral (PD-PI) cascade control to suppress the load frequency control (LFC) issues. The HHO based PID and PD-PI controllers are broadly implemented at two models with many circumstances for each model to ensure the eff ectiveness and the robustness of the proposed scheme at a high load disturbance, nonlinearity, and some critical parameters associated with the interconnected power system. First, a two-area non-reheat power plant is implemented, and the gains of PID and PD-PI controllers are adjusted using the proposed algorithm. In order to introduce extra realistic challenges, the governor-dead band is also modeled to ensure the robustness of the HHO/PD-PI in handling nonlinearity properties. Furthermore, to guarantee the suitability of the proposed HHO/PD-PI, a model with a mixture of power plants is carried out with and without the HVDC link, which is raised for the practical problems of LFC. Simulation results proved that; the proposed techniques HHO/PID and HHO/PD-PI provide superior performance compared to other reported strategies such as DE/PID, TLBO/PID, IGWO/PID, multi-objective/PID, and TLBO/2DOF-PID controllers. Finally, the dynamic investigation has also been completed using the random load pattern in system model-2, which shows the superior performance of HHO/PID and HHO/PD-PI schemes.
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