Study on the Thermally-Induced Stress and Relaxation of Ceramic Breeder Pebble Beds

Lotfy, Mahmoud,Ying, Alice,Abdou, Mohamed,Park, Yi-Hyun,Cho, Seungyon AMERICAN NUCLEAR SOCIETY, INC. 2017 Fusion science and technology Vol.72 No.3

Lightweight Self-consolidating Concrete with Expanded Shale Aggregates

Abdurrahmaan Lotfy,Khandaker M. A. Hossain,Mohamed Lachemi 한국콘크리트학회 2015 International Journal of Concrete Structures and M Vol.9 No.2

This paper presents statistical models developed to study the influence of key mix design parameters on the properties of lightweight self-consolidating concrete (LWSCC) with expanded shale (ESH) aggregates. Twenty LWSCC mixtures are designed and tested, where responses (properties) are evaluated to analyze influence of mix design parameters and develop the models. Such responses included slump flow diameter, V-funnel flow time, J-ring flow diameter, J-ring height difference, L-box ratio, filling capacity, sieve segregation, unit weight and compressive strength. The developed models are valid for mixes with 0.30?0.40 water-to-binder ratio, high range water reducing admixture of 0.3?1.2 % (by total content of binder) and total binder content of 410?550 kg/㎥. The models are able to identify the influential mix design parameters and their interactions which can be useful to reduce the test protocol needed for proportioning of LWSCCs. Three industrial class ESH?LWSCC mixtures are developed using statistical models and their performance is validated through test results with good agreement. The developed ESH?LWSCC mixtures are able to satisfy the European EFNARC criteria for self-consolidating concrete.

Optimum Controller Design Using the Ant Lion Optimizer for PMSG Driven by Wind Energy

Ahmed Lotfy Haridy,Al-Attar Ali Mohamed Abdelbasset,Ashraf Mohamed Hemeida,Ziad Mohamed Ali Elhalwany 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.1

The wind energy characteristics at the site not only indicate the amount of energy obtained from wind energy, but it also depends on the control strategy implemented on the wind energy conversion system. This study proposes an application of Ant Lion Optimizer (ALO) for tuning the classical (PI) controller parameters for the permanent magnet synchronous generator driven by wind energy system, to such an extent that the most maximum power point tracking can be acknowledged along with an improved fault ride-through capability. The optimized PI-controller parameters based ALO improving the low voltage ride through (LVRT) performance and the maximum power point tracking. ALO is implemented to the classical PI-controller on the machine side converter system, and grid side converter, for maximum power extraction from PMSG and enhancing LVRT. Four cases were considered in this paper, to examine the feasibility of the proposed ALO-PI controller. The suggested cases are system running at normal condition, a step-change in wind speed, wind speed variation at normal grid condition, and three-phase fault. A signifi cant improvement in the system dynamic performance when applying the ALO-PI controller is compared with classical PI-controller.

A Four Leg Shunt Active Power Filter Predictive Fuzzy Logic Controller for Low-Voltage Unbalanced-Load Distribution Networks

Fahmy, A.M.,Abdelslam, Ahmed K.,Lotfy, Ahmed A.,Hamad, Mostafa,Kotb, Abdelsamee The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

Recently evolved power electronics' based domestic/residential appliances have begun to behave as single phase non-linear loads. Performing as voltage/current harmonic sources, those loads when connected to a three phase distribution network contaminate the line current with harmonics in addition to creating a neutral wire current increase. In this paper, an enhanced performance three phase four leg shunt active power filter (SAPF) controller is presented as a solution for this problem. The presented control strategy incorporates a hybrid predictive fuzzy-logic based technique. The predictive part is responsible for the SAPF compensating current generation while the DC-link voltage control is performed by a fuzzy logic technique. Simulations at various loading conditions are carried out to validate the effectiveness of the proposed technique. In addition, an experimental test rig is implemented for practical validation of the of the enhanced performance of the proposed technique.

Fisheries and aquaculture sector of Egypt (The current situation - strategy and vision)

Ahmed Refat Aboelnour,Marwa Mamdouh Lotfy 한국수산해양기술학회(구 한국어업기술학회) 2017 한국수산해양기술학회 학술발표대회 Vol.2017 No.11

Subtractive versus additive indirect manufacturing techniques of digitally designed partial dentures

Ahmed Mamdouh Snosi,Shaimaa Mohamed Lotfy,Yasmine Galaleldin Thabet,Marwa Ezzat Sabet,Fardos Nabil Rizk 대한치과보철학회 2021 The Journal of Advanced Prosthodontics Vol.13 No.5

PURPOSE. The purpose of this in vitro study was to evaluate the accuracy of digitally designed removable partial denture (RPD) frameworks, constructed by additive and subtractive methods castable resin patterns, using comparative 3D analysis. MATERIALS AND METHODS. A Kennedy class III mod. 1 educational maxillary model was used in this study. The cast was scanned after modification, and a removable partial denture framework was digitally designed. Twelve frameworks were constructed. Two groups were defined: Group A: six frameworks were milled with castable resin, then casted by the lost wax technique into Co-Cr frameworks; Group B: six frameworks were printed with castable resin, then casted by the lost wax technique into Co-Cr frameworks. Comparative 3D analysis was used to measure the accuracy of the fabricated frameworks using Geomagic Control X software. Student’s t-test was used for comparing data. P value ≤ .05 was considered statistically significant. RESULTS. Regarding the accuracy of the occlusal rests, group A (milled) (0.1417 ± 0.0224) showed significantly higher accuracy than group B (printed) (0.02347 ± 0.0221). The same results were found regarding the 3D comparison of the overall accuracy, in which group A (0.1501 ± 0.0205) was significantly more accurate than group B (0.179 ± 0.0137). CONCLUSION. In indirect fabrication techniques, subtractive manufacturing yields more accurate RPDs than additive manufacturing.

A Four Leg Shunt Active Power Filter Predictive Fuzzy Logic Controller for Low-Voltage Unbalanced-Load Distribution Networks

A. M. Fahmy,Ahmed K. Abdelslam,Ahmed A. Lotfy,Mostafa Hamad,Abdelsamee Kotb 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

Recently evolved power electronics’ based domestic/residential appliances have begun to behave as single phase non-linear loads. Performing as voltage/current harmonic sources, those loads when connected to a three phase distribution network contaminate the line current with harmonics in addition to creating a neutral wire current increase. In this paper, an enhanced performance three phase four leg shunt active power filter (SAPF) controller is presented as a solution for this problem. The presented control strategy incorporates a hybrid predictive fuzzy-logic based technique. The predictive part is responsible for the SAPF compensating current generation while the DC-link voltage control is performed by a fuzzy logic technique. Simulations at various loading conditions are carried out to validate the effectiveness of the proposed technique. In addition, an experimental test rig is implemented for practical validation of the of the enhanced performance of the proposed technique.

Honey in Bronchial Asthma: From Folk Tales to Scientific Facts

Alzhraa Salah Abbas,Sherief Ghozy,Le Huu Nhat Minh,Mohammad Rashidul Hashan,Ali Lotfy Soliman,Nguyen Thanh Van,Kenji Hirayama,Nguyen Tien Huy 한국식품영양과학회 2019 Journal of medicinal food Vol.22 No.6

Bronchial asthma is one of the most common chronic inflammatory diseases. Complementary and alternative medicine is increasingly used for treating bronchial asthma. Ten electronic databases were searched to investigate whether honey alone or in combination with other ingredients can be considered as the potential treatment for bronchial asthma. Combinations of honey and Nigella sativa (NS) showed significant improvement in all pulmonary functions, including forced expiratory volume (FEV1) (MD = 0.52, P < .001), forced vital capacity (FVC) (MD = 0.55, P = .002), and peak expiratory flow rate (PEFR) (MD = 80.60, P < .001), in both moderate and severe, uncontrolled persistent asthma compared with baseline. Asthma control test scores also improved significantly (MD = 11.22, P < .001) in patients using combinations of honey and NS compared with baseline. Patients with a less severe grade of asthma showed a significant positive response in clinical parameters upon using honey. One study showed that using celery seeds and honey was associated with clinical improvement of both lung functions, FEV1 (MD = 18.09, P < .001) and FVC (MD = 24.23, P < .001), and respiratory parameters compared with baseline. In conclusion, honey alone has no strong evidence of being effective in controlling asthma. However, when used in combination with other substances, it showed a relatively high efficacy in patients with asthma. This finding may help in asthma control with lower cost alternatives and better outcomes.

Study of the gut microbiome as a novel target for prevention of hospital associated infections in intensive care unit patients

Suzan Ahmed Elfiky,Shwikar Mahmoud Ahmed,Ahmed Mostafa Elmenshawy,Gehad Mahmoud Sultan,Sara Lotfy Asser 대한중환자의학회 2023 Acute and Critical Care Vol.38 No.1

Background Hospital-acquired infections (HAIs) are increasing due to the spread of multi-drug-resistant organisms. Gut dysbiosis in an intensive care unit (ICU) patients at admission showed an altered abundance of some bacterial genera associated with the occurrence of HAIs and mortality. In the present study, we investigated the pattern of the gut microbiome in ICU patients at admission to correlate it with the development of HAIs during ICU stay. Methods Twenty patients admitted to an ICU with a cross-matched control group of 30 healthy subjects of matched age and sex. Quantitative SYBR green real-time polymerase chain reaction was done for the identification and quantitation of selected bacteria. Results Out of those twenty patients, 35% developed ventilator-associated pneumonia during their ICU stay. Gut microbiome analysis showed a significant decrease in Firmicutes and Firmicutes to Bacteroidetes ratio in ICU patients in comparison to the control and in patients who developed HAIs in comparison to the control group and patients who did not develop HAIs. There was a statistically significant increase in Bacteroides in comparison to the control group. There was a statistically significant decrease in Bifidobacterium and Faecalibacterium prausnitzii and an increase in Lactobacilli in comparison to the control group with a negative correlation between Acute Physiology and Chronic Health Evaluation (APACHE) II score and Firmicutes to Bacteroidetes and Prevotella to Bacteroides ratios. Conclusions Gut dysbiosis of patients at the time of admission highlights the importance of identification of the microbiome of patients admitted at the ICU as a target for preventing of HAIs.

Understanding the possible underlying mechanisms for low fouling tendency of the forward osmosis and pressure assisted osmosis processes

Lotfi, Fezeh,Chekli, Laura,Phuntsho, Sherub,Hong, Seungkwan,Choi, Joon Young,Shon, Ho Kyong Elsevier Scientific Pub. Co 2017 Desalination Vol. No.

<P><B>Abstract</B></P> <P>We investigated the possible underlying mechanism of the low fouling potential in the forward osmosis (FO) process during the osmotic dilution of seawater as part of the simultaneous desalination and wastewater reuse by FO and reverse osmosis hybrid system. Long-term experiments revealed an interesting water flux pattern highly dependent on the different operating parameters. The most interesting observation made was the spontaneous increase in the FO permeate flux at regular time interval during the FO operation using synthetic wastewater as feed and seawater. This sinusoidal FO flux pattern related well with the build-up of loose fouling layer and their natural peel-off from the membrane surface upon reaching certain layer thickness due to crossflow velocity shear. This flux pattern was more prominent at higher cross-flow velocity rates, lower feed water pH, for a smoother membrane surface and at lower operating pressure during pressure assisted osmosis (PAO) mode. Based on these results, membrane cleaning strategies were proposed by targeting a higher cross-flow velocity shear at a time when the permeate flux started to just increase. The approach of physical membrane cleaning was observed efficient and was able to almost fully restore the initial flux even under the PAO operation at 4bar.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An interesting water flux pattern was observed during osmotic dilution of seawater. </LI> <LI> It was related to the build-up of loose fouling layer peeled-off from the surface. </LI> <LI> This sinusoidal flux pattern was highly dependent on the operating parameters. </LI> <LI> Intrinsic membrane cleaning strategies can be adopted; avoiding plant down time. </LI> <LI> Increasing the feed cross-flow velocity at specific time was found most efficient. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>