Search

Your search keyword '"Ismaiel, Ahmed A."' showing total 164 results
Start Over Author "Ismaiel, Ahmed A."
164 results on '"Ismaiel, Ahmed A."'

2. Analytically Enhanced Random Walk Approach for Rapid Concentration Mapping in Fractured Aquifers

Author

Ahmed Yosri, Maysara Ghaith, Mohamed Ismaiel Ahmed, and Wael El-Dakhakhni

Subjects
concentration mapping, contaminant transport, discrete fracture network, fractured aquifers, random walk, single fractures, Hydraulic engineering, TC1-978, Water supply for domestic and industrial purposes, TD201-500
Abstract

The efficient management and remediation of contaminated fractured aquifers necessitate an accurate prediction of the spatial distribution of contaminant concentration within the system. Related existing analytical solutions are only applicable to single fractures and have not yet been extrapolated to the aquifer scale where a network of connected fractures exists. The Random Walk Particle Tracking (RWPT) method has been extensively adopted for concentration mapping in Discrete Fracture Networks (DFNs), albeit at exorbitant computational costs and without efficiently accommodating complex physical processes (e.g., two-site kinetics). This study introduces an analytically enhanced Spatiotemporal Random Walk (STRW) approach that facilitates the efficient time-dependent mapping of contaminant concentration in DFNs. The STRW approach employs a distribution function to simultaneously estimate the displacement of particles released through the system either instantaneously or over time. The STRW approach efficiently reproduced the contaminant concentration, calculated using available analytical solutions under a range of fate and transport mechanisms. The efficacy of the STRW approach is also confirmed in a synthetic impermeable DFN through replicating the concentration maps produced using the RWPT method. The developed approach represents an accurate and computationally efficient dynamic concentration mapping technique that can support the effective operation, management, and remediation of fractured aquifers under contamination events.

Published
2024
Full Text
View/download PDF

3. Process based calibration of a continental-scale hydrological model using soil moisture and streamflow data

Author

Ajay Ratna Bajracharya, Mohamed Ismaiel Ahmed, Tricia Stadnyk, and Masoud Asadzadeh

Subjects
Hydrological model, Nelson Churchill River Basin, Multi-objective optimization, Soil layer discretization, Permafrost, Climate change, Physical geography, GB3-5030, Geology, QE1-996.5
Abstract

Study region: Nelson Churchill River Basin (NCRB), Canada, and USA. Study Focus: Soil temperature and moisture are essential variables that fluctuate based on soil depth, controlling several sub-surface hydrologic processes. The Hydrological Predictions for the Environment (HYPE) model’s soil profile depth can vary up to four meters, discretized into three soil layers. Here, we further discretized the HYPE subsurface domain to accommodate up to seven soil layers to improve the representation of subsurface thermodynamics and water transfer more accurately. Soil moisture data from different locations across NCRB are collected from 2013 to 2017 for model calibration. We use multi-objective optimization (MOO) to account for streamflow and soil moisture variability and improve the model fidelity at a continental scale. New hydrological insights: Our study demonstrates that MOO significantly improves soil moisture simulation from the median Kling Gupta Efficiency (KGE) of 0.21–0.66 without deteriorating the streamflow performance. Streamflow and soil moisture simulation performance improvements are statistically insignificant between the original three-layer and seven-layer discretization of HYPE. However, the finer discretization model shows improved simulation in sub-surface components such as the evapotranspiration when verified against reanalysis products, indicating a 12 % underestimation of evapotranspiration from the three-layer HYPE model. The improvement of the discretized HYPE model and simulating the soil temperature at finer vertical resolution makes it a prospective model for permafrost identification and climate change analysis.

Published
2023
Full Text
View/download PDF

19. Thioredoxin Is a New Target for the Phytotoxicity of Small Lactone Mycotoxins, Patulin and Penicillic Acid on Maize Seedlings

Author

Ismaiel, Ahmed A., Papenbrock, Jutta, Ismaiel, Ahmed A., and Papenbrock, Jutta

Abstract

The phytotoxic mechanisms of patulin (PAT) and penicillic acid (PA) have not been identified unambiguously. This study aims to clarify their effects on thioredoxins (Trxs). Aflatoxin B1 (AFB1), PAT and PA were isolated by solvent extraction and chromatographic techniques from the cultures of Aspergillus flavus Z2 (LC171449), Penicillium vulpinum CM1 and Aspergillus ochraceus EMCC516, respectively. The three mycotoxins showed phytotoxicity to the germination of maize seeds, which was manifested by inhibiting radicle and coleoptile emergence, in addition to their toxic effects on fresh weights and root and shoot lengths. The phytotoxicity of AFB1 and PAT was greater than that of PA. Due to the central roles exhibited by plant Trxs in cellular metabolic activities, they were tested as target proteins for PAT and PA using AFB1 as positive control. In vivo studies showed that the mycotoxins significantly reduced Trx activity measured in the roots and shoots of maize seedlings. PAT showed greater Trx-inhibiting activity than PA and AFB1. In vitro studies of the mycotoxins on Trx y1 (from Arabidopsis thaliana) and thioredoxin reductase (Tr, from rat liver) activities confirm the results of in vivo studies. The inactivation of Trx with PAT and PA was reduced in the presence of glutathione (GSH). Data obtained suggest that lactone mycotoxins are more highly reactive with simple low-molecular-weight thiols (like GSH) than with complex ones (like Trx).

Published
2023

37. Digital control strategy for SPWM MPPT of PV system with three-phase NPC three-level converter

Author

Ismaiel Ahmed, Vladislav Oboskalov, and Mahmoud Aref

Subjects
Control and Optimization, Computer Networks and Communications, PV, INVERTER, Maximum power point tracking, Stand-alone, MULTI-LEVEL, Control theory, LCL filter, Digital control, Inverter, Electrical and Electronic Engineering, Grid, Mathematics, STAND-ALONE, Total harmonic distortion, LCL FILTER, Photovoltaic system, Three-phase, Hardware and Architecture, Signal Processing, Multi-level, Harmonic, GRID, Low voltage, Information Systems
Abstract

This paper is aimed at investigating MPPT of PV system controlled by SPWM which is generated by comparing sinusoidal wave with variable frequency sawtooth wave. Perturb and Observe (P&O) method is used for MPPT control of PV system. NPC three-phase three-level converter with LCL filter is designed to produce output voltage with minimum Total Harmonic Distortion (THD) and high efficiency. The simple and fast method to get MPP of PV system with variable irradiation is digital control where the maximum power point is obtained from look-up table for the values of optimum voltage that achieve the maximum power for each irradiance value is used for digital control signal in microcontroller. The output voltage harmonic of multi-level three-phase inverter is controlled using SPWM control. THD of output voltage of multi-level three-phase inverter is 22% of stand-alone and grid-connected PV system. Small rate LCL filter is used to limit voltage harmonics within medium and low voltage limits (5%). THD output voltage of LCL filter is 4.9% and 3.51% of stand-alone and grid-connected PV system respectively. Copyright © 2020 Institute of Advanced Engineering and Science. All rights reserved.

Published
2020

42. Abstract 338: Peripheral blood monocyte count prediction for anti-HER2 combination therapy: Outcomes in HER2-positive metastatic breast cancer patients

Author

Shahrazad Abdulsalam Alzahrani, Amer Naeem Radwi, Dalia Ismaiel Ahmed, Haneen Abdulrahman Aljohani, Raghad Abdulrahman Alahmadi, and Reyadh Khalid Albeladi

Subjects
Oncology, Cancer Research, medicine.medical_specialty, Chemotherapy, Combination therapy, business.industry, medicine.medical_treatment, Cancer, medicine.disease, Peripheral blood mononuclear cell, Metastatic breast cancer, Breast cancer, Trastuzumab, Internal medicine, medicine, Pertuzumab, skin and connective tissue diseases, business, medicine.drug
Abstract

Background: Breast cancer is the commonest cancer in Saudi Arabia and worldwide. Nineteen percent of breast cancers are HER2-positive. Both trastuzumab and pertuzumab inhibit cancer cell proliferation by blocking HER2 activation and HER2-mediated downstream signals. They also induce extracellular antibody-dependent cell-mediated cytotoxicity (ADCC), exerted by immune cells expressing surface CD16 Fcγ receptors (FcγRs), such as NK cells subset of human blood monocytes. Inside tissue, monocytes differentiate to macrophages and potentiate anti-cancer innate immunity. Increased macrophages' infiltration in the tumor tissue was associated with enhanced efficacy of trastuzumab antitumor efficacy in mouse xenograft tumor models. In Metastatic HER2-positive breast cancer, increased M1 polarized macrophages improved survival and were independent prognostic predictors. Herceptin significantly increased peripheral blood monocyte (PBMC) cytotoxicity against HER-2 positive cancer cells. This study aims to determine the impact of peripheral blood monocyte (PBMC) count on response rate (RR) and progression-free survival (PFS) in metastatic HER2-positive breast cancer patients treated with trastuzumab and pertuzumab. Method: A retrospective chart review at Princess Norah Oncology Center (PNOC) that included histopathology-proven metastatic HER2-positive breast cancer patients receiving first-line anti-HER2 systemic therapy from January 2008 to May 2018. Younger patients (< 18 years old) and those with cranial and immeasurable metastases were excluded. Before each chemotherapy cycle, peripheral blood monocyte counts (PBMC) were checked, and values were classified as high, low, or normal according to hospital lab reference ranges. Chi-square and Kaplan-Meier curves were applied to estimate response rate (RR) and progression-free survival (PFS). Results: Of 307 identified cases, 81 were analyzed. The median age was 62 years, 73% were postmenopausal, and 70% had grade 3 tumors. All had visceral metastases, treated with chemotherapy, along with an anti-HER2 agent. We found improved RR with high PBMC before the second cycle (P = 0.025) and increased PFS for high PBMC before the third cycle (P = 0.048). Conclusion(s): Peripheral blood monocyte count before cycle 2 and 3 might predict a favorable outcome of chemotherapy anti-HER2 combination in metastatic HER2-positive breast cancer. Citation Format: Amer Naeem Radwi, Reyadh Khalid Albeladi, Shahrazad Abdulsalam Alzahrani, Raghad Abdulrahman Alahmadi, Haneen Abdulrahman Aljohani, Dalia Ismaiel Ahmed. Peripheral blood monocyte count prediction for anti-HER2 combination therapy: Outcomes in HER2-positive metastatic breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 338.

Published
2021

44. Türk romanında Endülüs

Author

Ahmed İsmaiel, Ahmed Abdelhaliem, Aygün, Özcan, and Türk Dili ve Edebiyatı Anabilim Dalı

Subjects
Tarih, History, Turkish novel, Türk Dili ve Edebiyatı, Civilization, Turkish Language and Literature, Andalucia, Turkish literature, Turkish history, Novel, Conquest
Abstract

İslam orduları tarafından Endülüs'ün fethi ile başlayan ve yıkılışına kadar yaşanan olaylar ilmî ve edebi yönden araştırmalara konu olmuştur. Endülüs medeniyeti ve eserleri tarih kitaplarında ve edebi eserlerde yerini almıştır. Endülüs alimleri ve bilim adamlarının insalığa bıraktığı, çalışmalar, kültür eserleri her zaman merak unsuru olmuştur.Türk edebiyatında Endülüs, ilk olarak Tanzimat dönemi eserlerinde konu olarak işlenmeye başlamıştır. Türk edebiyatçılar tarafından Endülüs imajının tema olarak işlendiği romanlar genel olarak, Endülüsün fethi ve yıkılışını anlatmaktadır. Türk romanında Endülüs imajı araştırmamızda, romanların edebi incelemeleri ve gerçek tarih ile benzerliklerini konu başlıkları ile belirtirmiştir. Anahtar Kelimeler: Endülüs, Türk Edebiyatı, Türk Romanı, Fetih, Medeniyet, Çöküş. Andalusia trough its concuqest to its fall been a topic for bunch of scientific and literary resarches. Andalusia had its places in historic and literary books. By its history, culture, scientist and their inventions, Andalua always been an interesting topic for people all around the world.In Turkish literary, Andalucia first appeared at tanzimat period. In Turkish literary Andalusia been in their novels by its fall and conquest. Novels, analysed by comparing historic sources, articles and thesis.Key Words : Andalucia, Turkish Literature, Turkish Novels, civilization, Control, Downfall. 512

Published
2019

45. Andalusia in the Turkish novel

Author

İsmaiel, Ahmed Abdelhaliem Ahmed, Aygün, Özcan, and Sosyal Bilimler Enstitüsü

Subjects
Endülüs, Fetih, Turkish Novels, Çöküş, Downfall, Control, Türk Edebiyatı, Civilization, Turkish Literature, Medeniyet, Türk Romanı, Andalucia
Abstract

İslam orduları tarafından Endülüs’ün fethi ile başlayan ve yıkılışına kadar yaşanan olaylar ilmî ve edebi yönden araştırmalara konu olmuştur. Endülüs medeniyeti ve eserleri tarih kitaplarında ve edebi eserlerde yerini almıştır. Endülüs alimleri ve bilim adamlarının insalığa bıraktığı, çalışmalar, kültür eserleri her zaman merak unsuru olmuştur. Türk edebiyatında Endülüs, ilk olarak Tanzimat dönemi eserlerinde konu olarak işlenmeye başlamıştır. Türk edebiyatçılar tarafından Endülüs imajının tema olarak işlendiği romanlar genel olarak, Endülüsün fethi ve yıkılışını anlatmaktadır. Türk romanında Endülüs imajı araştırmamızda, romanların edebi incelemeleri ve gerçek tarih ile benzerliklerini konu başlıkları ile belirtirmiştir. Andalusia trough its concuqest to its fall been a topic for bunch of scientific and literary resarches. Andalusia had its places in historic and literary books. By its history, culture, scientist and their inventions, Andalua always been an interesting topic for people all around the world. In Turkish literary, Andalucia first appeared at tanzimat period. In Turkish literary Andalusia been in their novels by its fall and conquest. Novels, analysed by comparing historic sources, articles and thesis.

Published
2019

46. Rotating range sensor approached for mobile robot obstacle detection and collision avoidance applications.

Author

Ismaiel, Ahmed, Filimonov, M. Yu., Pasheva, Vesela, Popivanov, Nedyu, and Venkov, George

Subjects
*MOBILE robots, *SERVOMECHANISMS, *DETECTORS, *OBSTACLE avoidance (Robotics), *MOBILE apps
Abstract

Range finder sensors are widely used in the obstacle detection and collision avoidance applications. In this research, we propose rotating range finder sensor that provides economic and efficient solution for mobile robot applications. Rotating approach is achieved by coupling the range sensors with servomotor. In this article, rotating approach model design, main parameters, equations and limitation are described. In addition, an algorithm is developed to control the rotation angle of the range sensor, extract data from the approach and analyze it. A case study of the rotating approach by implementing ultrasonic sensor is simulated and the results are obtained. Simulation platform Gazebo and ROS are used to simulate the rotating approach. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

47. A simulation-based study to calculate all the possible trajectories of differential drive mobile robot.

Author

Ismaiel, Ahmed, Filimonov, M. Yu., Pasheva, Vesela, Popivanov, Nedyu, and Venkov, George

Subjects
*MOBILE robots, *EXPERIMENTAL design
Abstract

Deferential Drive Mobile Robot (DDMR) is being used in many applications as it is easy to be modeled and controlled. This research presents the idea of using DDMR turning motion behavior to develop an algorithm that calculate all the circular trajectories. This can be used to navigate DDMR in a curvature paths instead of linear ones. In this research we design and simulate Differential Drive Mobile Robot (DDMR) model. Then we use the simulated model to calculate all the possible trajectories that DDMR can follow with each left and right wheel velocity configurations. Results are saved in a navigation look-up table that can be implemented in DDMR navigation's approach. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

48. Microcontroller Look-up Table of Digital Control MPPT of PV System

Author

Anatolijs Mahnitko, Vladislav Oboskalov, Aleksandrs Gavrilovs, Mahmoud Aref, and Ismaiel Ahmed

Subjects
Sine wave, Maximum power principle, Control theory, Computer science, Photovoltaic system, Harmonic, Inverter, Digital control, Sawtooth wave, Maximum power point tracking
Abstract

This paper is aimed at investigating MPPT of PV system controlled by SPWM which is generated by comparing sinusoidal wave with variable frequency sawtooth wave. Perturb and Observe (P&O) method is used for MPPT control of PV system. The simple and fast method to get MPP of PV system with variable irradiation is digital control where the maximum power point is obtained from look-up table for the values of optimum voltage that achieve the maximum power for each irradiance value is used for digital control signal in microcontroller. The output voltage harmonic of multi-level three-phase inverter is controlled using SPWM control.

Published
2018

Catalog

Books, media, physical & digital resources
See catalog results