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"Omar, Mohamed"
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Progress in Modeling and Control of Gas Turbine Power Generation Systems: A Survey
This paper reviews the modeling techniques and control strategies applied to gas turbine power generation plants. Recent modeling philosophies are discussed and the state-of-the-art feasible strategies for control are shown. Research conducted in the field of modeling, simulation, and control of gas turbine power plants has led to notable advancements in gas turbines’ operation and energy efficiency. Tracking recent achievements and trends that have been made is essential for further development and future research. A comprehensive survey is presented here that covers the outdated attempts toward the up-to-date techniques with emphasis on different issues and turbines’ characteristics. Critical review of the various published methodologies is very useful in showing the importance of this research area in practical and technical terms. The different modeling approaches are classified and each category is individually investigated by reviewing a considerable number of research articles. Then, the main features of each category or approach is reported. The modern multi-variable control strategies that have been published for gas turbines are also reviewed. Moreover, future trends are proposed as recommendations for planned research.
Journal Article
Antibacterial Evaluation, In Silico Characters and Molecular Docking of Schiff Bases Derived from 5-aminopyrazoles
A series of Schiff bases 14–25 were designed and synthesized for evaluation of their antibacterial properties against multi-drug resistant bacteria (MDRB). The antibacterial activities of Schiff bases 14–25 showed that most of the synthesized compounds displayed a significant antibacterial activity. Assessment of in silico ADMET properties (absorption, distribution, metabolism, excretion and toxicity) of Schiff bases illustrates that all derivatives showed agreement to the Lipinski’s rule of five. Further enzymatic assay aided by molecular docking study demonstrated that compound 18 is a potent inhibitor of staphylococcus aureus DNA gyrase and dihydrofolate reductase kinases. This study could be valuable in the discovery of new potent antimicrobial agents.
Journal Article
Optimization of fused deposition modeling process parameters: a review of current research and future prospects
Fused deposition modeling (FDM) is one of the most popular additive manufacturing technologies for various engineering applications. FDM process has been introduced commercially in early 1990s by Stratasys Inc., USA. The quality of FDM processed parts mainly depends on careful selection of process variables. Thus, identification of the FDM process parameters that significantly affect the quality of FDM processed parts is important. In recent years, researchers have explored a number of ways to improve the mechanical properties and part quality using various experimental design techniques and concepts. This article aims to review the research carried out so far in determining and optimizing the process parameters of the FDM process. Several statistical designs of experiments and optimization techniques used for the determination of optimum process parameters have been examined. The trends for future FDM research in this area are described.
Journal Article
1D hydrogen engine modeling to investigate air-fuel ratio, spark timing, and water injection effects on performance and emissions
This study presents a comprehensive 1D modeling and simulation of a hydrogen-fueled internal combustion engine, focusing on the impacts of air-fuel ratio, spark timing, and water injection on performance and emissions. Using a single-cylinder BMW F650 GS engine as a baseline, simulations were conducted in Ricardo WAVE to evaluate engine behavior under varying conditions. Results demonstrate that hydrogen fueling reduces CO emissions to negligible levels but increases NO
x
emissions under specific conditions due to elevated combustion temperatures. Water injection effectively mitigates NO
x
formation and enhances volumetric efficiency while slightly compromising power output at high hydrogen-to-water ratios. The findings highlight hydrogen’s potential as a sustainable fuel for internal combustion engines and underline the importance of optimizing operating parameters to balance performance, efficiency, and emissions. This research contributes valuable insights into the development of cleaner, hydrogen-powered transportation solutions.
Journal Article
Effects of propolis-loaded nanoliposomes fortification in extender on buffalo semen cryopreservation
Buffalo sperm is sensitive to cryoinjuries, thus improving sperm cryoresistance is a critical approach for wide spreading the assisted reproductive technologies in buffalo. The intention of this work was to assess the effect of propolis-loaded in nanoliposomes (PRNL) supplementation of semen extender on semen quality, antioxidant status and some apoptotic genes of cryopreserved buffalo semen. PRNL were prepared using cholesterol (Chol) as well as soybean lecithin and their physicochemical properties were characterized. Egyptian buffalo bulls (4–6 years) were involved, and the semen samples were collected using the artificial vagina method. Buffalo semen was pooled (n = 25 ejaculates) and cryopreserved in tris extender containing PRNL at 0 (PRNL0), 2 (PRNL2), 4 (PRNL4) and 6 µg/mL (PRNL6), respectively. The PRNL had a size of 113.13 nm and a negative zeta potential (− 56.83 mV). Sperm progressive motility, viability, membrane integrity, abnormalities, chromatin damage, redox status, apoptosis status, and apoptotic genes were investigated after post-thawed buffalo semen. Using 2 or 4 µg/mL PRNL significantly increased sperm progressive motility, viability, and membrane integrity, while sperm abnormalities and the percentage of chromatin damages were the lowest in PRNL2 group. Moreover, the PRNL2 group exhibited the best results for all antioxidative activities (TAC, SOD, GPx and CAT) with significantly higher levels than the other groups (
P
< 0.05). The levels of ROS and MDA were significantly lower in the PRLN2 compared with other groups. The sperm caspase 3 enzyme activities showed the lowest values in PRNL2 groups followed by PRNL4 and PRNL6 groups with significant differences compared with the control. Adding 2 µg/mL PRNL to freezing media significantly reduced apoptotic genes such as
Bax
and
Caspase 3
in sperm, while significantly increase in
Bcl2
expression compared with the control (
P
< 0.001). The expression of
Bcl2, Caspase 3
and
Bax
genes in sperm were not affected by the 6 µg/mL PRNL addition (
P
> 0.05). The electron micrography descriptions exemplified that the fortification of 2 or 4 µg/mL PRNL maintained the acrosomal and plasma membrane integrities as well as sustained the ultrastructure integrity of the cryopreserved buffalo spermatozoa when compared with control group, whereas the 6 µg/mL of PRNL demonstrated highest injury to the acrosome and plasma membranes. Results show supplementation of the buffalo freezing extender with 2 or 4 µg/mL of PRNL enhanced post-thawed sperm quality via boosting the antioxidant indices, diminishing the oxidative stress and apoptosis as well as maintained the ultrastructure integrity of frozen-thawed buffalo sperm.
Journal Article
Determination and Mapping of Regional Change of Pb and Cr Pollution in Ankara City Center
As in the whole world, environmental problems have increased with the increase in residential areas in Turkey, and this situation has brought many problems, especially environmental pollution. Among the components of environmental pollution, heavy metals are the most dangerous and important in terms of human and environmental health. Especially Pb and Cr are among the most toxic and deadly heavy metals, and the concentrations of these heavy metals in the environment are constantly increasing. Soil is one of the elements most affected by the increase in pollution. Soils are both a nutrition and living environment for plants and one of the most important components of the environment. In addition, topsoil is one of the most important indicators of the level of air pollution. This study aimed to determine and map the Pb and Cr pollution in the city center of Ankara, the capital and the second-largest city of Turkey, with the help of topsoils. Within the scope of the study, Ankara city center was divided into sub-regions with different characteristics, and Pb and Cr analyzes were performed by taking topsoil samples from 50 points representing these regions. Then, the changes in Pb and Cr concentrations on a regional basis were statistically evaluated, the data were transferred to Geographic Information Systems (GIS) using ArcGIS 10.7 software, then modeled with the kriging method, one of the interpolation methods, and pollution maps were created. As a result of the study, it has been determined that the Cr concentration is generally higher in the northwest-southeast axis of the study area, decreases as one goes to the northeast and southwest, and the region with the highest Pb concentration is located in the center of the study area, that is, in the west of the town of Sincan.
Journal Article
Increasing the performance of cucumber (Cucumis sativus L.) seedlings by LED illumination
Light is one of the most important limiting factors for photosynthesis and the production of plants, especially in the regions where natural environmental conditions do not provide sufficient sunlight, and there is a great dependence on artificial lighting to grow plants and produce food. The influence of light intensity, quality, and photoperiod on photosynthetic pigments content and some biochemical and growth traits of cucumber seedlings grown under controlled conditions was investigated. An orthogonal design based on a combination of different light irradiances, ratio of LEDs and photoperiods was used. Treaments consisted of three light irradiance regimes (80, 100, and 150 µmol m
−2
s
−1
) provided by light-emitting diodes (LEDs) of different ratios of red and blue (R:B) (30:70, 50:50, and 70:30) and three different photoperiods (10/14, 12/12, and 14/10 h). The white light was used as a control/reference. Plant height, hypocotyl length, stem diameter, leaf area, and soluble sugar content were highest when exposed to LM9 (150 µmol m
−2
s
−1
; R70:B30; 12/12 h) light mode, while the lowest values for the above parameters were obtained under LM1 (80 µmol m
−2
s
−1
; R30:B70; 10/14 h). Higher pigments contents (chlorophyll
a
, chlorophyll
b
, and carotenoid) were obtained when light regime LM9 (150 µmol m
−2
s
−1
; R70:B30; 12/12 h) was applied. In general, cucumber seedlings grown under the LM9 regime showed a significant increase in growth as well as photosynthetic capacity. It seems that the content of photosynthetic pigments is the key factor responsible for the performance of cucumber seedlings grown under different lighting modes, compared to other traits studied. We recommend monitoring the content of chlorophyll
a, b
, and their ratio value when studying the light requirement of cucumber plants.
Journal Article
Fiscal Rules and Debt Sustainability in Somalia: A Pathway to the Post-HIPC Prudent Macroeconomic Policy
The successful fulfillment of the Heavily Indebted Poor Countries (HIPC) conditions and the subsequent debt relief mark a significant milestone for Somalia, opening avenues for accessing financing facilities. However, prudent macroeconomic policies balancing high-priority development goals and future debt sustainability are essential to avoid new debt crises. This study aims to investigate the role of fiscal rules in controlling future debt trajectory. The study employs a multivariate time series Vector Autoregressive (VAR) estimation and forecasting method to analyse quarterly data on Somali debt and fiscal variables from 2009 to 2023. The results indicate an inverse bidirectional causality between public revenue and external debt and a positive unidirectional impact of public spending on debt. Furthermore, the impulse response results demonstrate that debt volatility triggered by external shocks via fiscal deviations lasts four to eight quarters before converging to the original path. In addition, the variance decomposition findings reveal that deviations in revenue and expenditure targets account for up to 16.7% and 20.2% of the variations in external debt, respectively, after eight quarters. Finally, based on the baseline levels, the out-of-the-sample forecasts predict that the debt trajectory will remain sustainable for years until it reaches a crisis level around 2030. Robustly withstanding rigorous empirical tests, the study results proved to be consistently stable, providing solid economic policy implications for the next phase of Somalia’s development journey.
Journal Article
Pharmacological Properties of 4′, 5, 7-Trihydroxyflavone (Apigenin) and Its Impact on Cell Signaling Pathways
Plant bioactive compounds, particularly apigenin, have therapeutic potential and functional activities that aid in the prevention of infectious diseases in many mammalian bodies and promote tumor growth inhibition. Apigenin is a flavonoid with low toxicities and numerous bioactive properties due to which it has been considered as a traditional medicine for decades. Apigenin shows synergistic effects in combined treatment with sorafenib in the HepG2 human cell line (HCC) in less time and statistically reduces the viability of tumor cells, migration, gene expression and apoptosis. The combination of anti-cancerous drugs with apigenin has shown health promoting potential against various cancers. It can prevent cell mobility, maintain the cell cycle and stimulate the immune system. Apigenin also suppresses mTOR activity and raises the UVB-induced phagocytosis and reduces the cancerous cell proliferation and growth. It also has a high safety threshold, and active (anti-cancer) doses can be gained by consuming a vegetable and apigenin rich diet. Apigenin also boosted autophagosome formation, decreased cell proliferation and activated autophagy by preventing the activity of the PI3K pathway, specifically in HepG2 cells. This paper provides an updated overview of apigenin’s beneficial anti-inflammatory, antibacterial, antiviral, and anticancer effects, making it a step in the right direction for therapeutics. This study also critically analyzed the effect of apigenin on cancer cell signaling pathways including the PI3K/AKT/MTOR, JAK/STAT, NF-κB and ERK/MAPK pathways.
Journal Article