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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.
Fatigue Crack Tip Plasticity for Inclined Cracks
Hesham El-Emam,Alaaeldin Elsisi,Hani Salim,Hossam Sallam 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.2
The evaluation of the crack tip deformation is essential to the estimation of crack growth under either static or cyclic loading. A 3-D elastic–plastic fi nite element analysis was developed to simulate the crack tip deformation along mixed mode inclined edge cracks in a steel plate subjected to either monotonic or cyclic loading at selected R-ratios. In this paper, two types of crack confi gurations were investigated: inclined cracks with equal inclined lengths (EICL) and inclined cracks with equal horizontal projection length (ECHP). The development of the monotonic (Δm) and cyclic (Δc) crack tip plastically zones and the monotonic (CTOD) and cyclic (ΔCTOD) crack tip opening displacements were traced to fi nd the eff ect of the crack inclination angle, which signifi cantly aff ected the size and shape of the crack tip plastic zone. The fi nite element results compared well with the analytical results based on modifi ed Dugdale’s model. It was observed that Mode II has a signifi cant eff ect on the plastic zone in the case of equal inclined crack length (EICL), i.e., Mode II increases as the crack angle decreases. Also, it is interesting to note that for the EICL case, the magnitude of Δc is delayed to appear with decreasing the inclination angle, for example, for θ = 90° the cyclic plastic zone appeared at Δσ = 103.32 MPa, while for θ = 45° the cyclic plastic zone appeared at Δσ = 132.84 MPa. Whereas, the variation of monotonic and cyclic plastic zone size in the equal crack horizontal projection (ECHP) case is not aff ected by the crack inclination angle. Furthermore, it was observed that the static crack tip opening displacement (CTOD) and the cyclic (ΔCTOD) are independent of the crack inclination angle in case of ECHP, due to such cracks take into consideration the eff ect of inclination angle through its length.
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.
Seasonal Forecasting of Rainfall and Runoff Volumes in Riyadh Region, KSA
Hesham Fouli,Rabie Fouli,Bashar Bashir,Oumar A. Loni 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.7
Analyses of Total Quarterly Rainfall (TQR) depth time series (1964 – 2014) at four gauges surrounding one potential rainwaterharvesting site in this region show strong temporal and spatial variability. Using Box-Jenkins Methodology, three best-fit seasonalARIMA models for 10-year predictions of TQR were selected; among more than 20 models, based on criteria of minimum values ofvariance, AIC and SBC. Comparisons between the forecasted and the actual TQR show good agreement. Data analyses show thatspring records have the heaviest rainfall. Accuracy assessment results of the models indicate that for the most favorable model 58%of the residuals are within ± 10 mm, and 74% are within ± 20 mm. Making use of these results, it was possible to obtain seasonalpredictions of runoff volumes for water harvesting at the potential site. The results indicate that the largest runoff volumes areexpected to occur during the springs of 2016, 2019 and 2022 with an estimate of approximately 3.764 Mm3. Such results are usefulfor the design and maintenance of the storage facilities of the harvested water.
An Anchorage Technique for Shear Strengthening of RC T‑Beams Using NSM‑BFRP Bars and BFRP Sheet
Hesham M. Diab,Ahmed M. Sayed 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.5
This study presents a detailed experimental program for reinforced concrete T-beams strengthened in shear with near-surface mounted (NSM) basalt fiber-reinforced polymer (BFRP) bars. This paper aims to introduce and evaluate a nonmechanical anchorage technique for shear strengthening using NSM-BFRP bars. T-beams were strengthened using manually manufactured closed or U-shaped hybrid BFRP stirrups (BFRP bars and BFRP sheets). The experimental program was developed to study the effects of these anchorage techniques. The results showed that the shear capacity increased by 8%–46% for beams strengthened with NSM-BFRP bars without anchorage. However, the presence of the proposed anchorage system increased the shear capacity of the strengthened beams by 39.6%–81.6%. Moreover, the maximum strains induced in the BFRP bars ranged from 27 to 59% of their ultimate strains according to the spacing between the NSM and the presence of the anchorage. The proposed anchorage technique prevented the premature debonding of the NSM-BFRP bars.
Developing an Outcome-Based Industrial and Systems Engineering Program
Hesham K. Alfares,Umar M. Al-Turki,Saleh O. Duffuaa 대한산업공학회 2010 Industrial Engineeering & Management Systems Vol.9 No.1
In this paper, a systematic methodology is proposed for developing an outcome-based undergraduate Industrial and Systems Engineering Program at the Systems Engineering Department of King Fahd University of Petroleum & Minerals (KFUPM) in Saudi Arabia. This program is an upgrade of the Industrial Engineering and Operations Research (IE/OR) option, which has been in existence since 1984 and has been revised several times since then. The methodology and process used is motivated by the Accreditation Board for Engineering and Technology (ABET) 2000 criteria and has been employed to develop the program’s objectives and outcomes. Subsequently, a curriculum is designed that is expected to deliver the objectives and outcomes. The paper presents the methodology, objectives, outcomes and the developed curriculum of the outcome-based program.