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result(s) for
"Al-Qarawi, Ahmed"
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Geotechnical Design Practices and Soil–Structure Interaction Effects of an Integral Bridge System: A Review
by
Leo, Chin Jian
,
Liyanapathirana, Samanthika
,
Sigdel, Lila Dhar
in
Bearings
,
Bridges
,
cyclic temperature loading
2021
Integral bridges are a class of bridges with integral or semi-integral abutments, designed without expansion joints in the bridge deck of the superstructure. The significance of an integral bridge design is that it avoids durability and recurring maintenance issues with bridge joints, and maybe bearings, which are prevalent in traditional bridges. Integral bridges are less costly to construct. They require less maintenance and therefore cause less traffic disruptions that incur socio-economic costs. As a consequence, integral bridges are becoming the first choice of bridge design for short-to-medium length bridges in many countries, including the UK, USA, Europe, Australia, New Zealand and many other Asian countries. However, integral bridge designs are not without challenges: issues that concern concrete creep, shrinkage, temperature effects, bridge skew, structural constraints, as well as soil–structure interactions are amplified in integral bridges. The increased cyclic soil–structure interactions between the bridge structure and soil will lead to adverse soil ratcheting and settlement bump at the bridge approach. If movements from bridge superstructures were also transferred to pile-supported substructures, there is a risk that the pile–soil interactions may lead to pile fatigue failure. These issues complicate the geotechnical aspects of integral bridges. The aim of this paper is to present a comprehensive review of current geotechnical design practices and the amelioration of soil–structure interactions of integral bridges.
Journal Article
Response of growth and drought tolerance of Acacia seyal Del. seedlings to arbuscular mycorrhizal fungi
by
Aref, Ibrahim M.
,
Al-Qarawi, Abdulaziz A.
,
Ahmed, Abdalla I.
in
abiotic stress
,
Acacia seyal
,
Arbuscular mycorrhizas
2020
Considering the improvement of acacia species growth in arid and semi-arid environment, a pot experiment was conducted to evaluate the role of arbuscular mycorrhizal fungi (AMF); Funneliformis mosseae (syn. Glomus mosseae), Rhizophagus intraradices (syn. Glomus intraradices) and Claroideoglomus etunicatum (syn. Glomus etunicatum) on growth and drought tolerance of Acacia seyal Del. seedlings under drought cycles (7, 14, 21 and 28 days). AMF-inoculated seedlings showed a clear colonisation percentage (36–68%). AMF treatment significantly improved seedlings shoot and root growth under all drought cycles compared to non-AMF control seedlings. Moreover, AMF treatment enhanced seedlings drought resistance by increasing root surface area (root length increased by 483.76% and root tips number increased by 1 463.94% under 28 days of drought cycle), there was a strong linear relation between proline accumulation, AMF and drought stress (proline content decreased in treated seedlings by 31.3% and 14.3% and increased by 97.5% and 80.4% in untreated seedlings under drought cycles of 21 and 28 days, respectively). In conclusion, the AMF inoculation improved growth and enhanced drought tolerance of A. seyal seedlings and can be used as a natural biostimulator for acacias seedlings establishment in arid areas.
Journal Article
Promising Application of Automated Liquid Culture System and Arbuscular Mycorrhizal Fungi for Large-Scale Micropropagation of Red Dragon Fruit
by
Malik, Jahangir A.
,
Habib, Muhammad M.
,
Alwahibi, Mona S.
in
acclimation
,
Acclimatization
,
Arbuscular mycorrhizas
2023
Red dragon fruit (Hylocereus polyrhizus) is an economic and promising fruit crop in arid and semi-arid regions with water shortage. An automated liquid culture system using bioreactors is a potential tool for micropropagation and large-scale production. In this study, axillary cladode multiplication of H. polyrhizus was assessed using cladode tips and cladode segments in gelled culture versus continuous immersion air-lift bioreactors (with or without a net). Axillary multiplication using cladode segments (6.4 cladodes per explant) was more effective than cladode tip explants (4.5 cladodes per explant) in gelled culture. Compared with gelled culture, continuous immersion bioreactors provided high axillary cladode multiplication (45.9 cladodes per explant) with a higher biomass and length of axillary cladodes. Inoculation of H. polyrhizus micropropagated plantlets with arbuscular mycorrhizal fungi (Gigaspora margarita and Gigaspora albida) significantly increased the vegetative growth during acclimatization. These findings will improve the large-scale propagation of dragon fruit.
Journal Article
Soil Physicochemical and Metagenomic Analyses of Bacteria and Fungi: Toward Desert Truffle Cultivation in Saudi Arabia
by
Al-Hejin, Ahmed M.
,
Al-Qarawi, Abdulaziz A.
,
Thomas, Paul W.
in
Agriculture
,
Analysis
,
Bacteria
2024
Researchers are exploring plant-based protein sources to address both malnutrition and climate change. Desert truffles are rich in protein (i.e., ≈20%) and offer a cheaper and more environmentally friendly option. However, desert truffle cultivation is limited by environmental factors like rainfall and soil properties. This study was conducted to understand the soil conditions and microbiomes associated with desert truffles growing in parts of Saudi Arabia. Based on yield, the truffle fields were categorized into high-yield (≈50 kg/ha annually) and low-yield (≈2 kg/ha annually) truffle farms. Truffle yield differences were not significantly influenced by most soil physicochemical variables except for total nitrogen (negatively correlated). However, low soil nitrogen alone did not explain yield disparities, as wild truffle fields with low nitrogen also produced fewer truffles. In contrast, truffle yield showed a strong positive correlation with calcium carbonate content. We hypothesized that the unmeasured irrigation schedule was most likely behind the truffle yield differences especially during fruiting season. Furthermore, the high-yield farms had lower bacteria richness and diversity than the low-yield farms. Environmentally important bacteria genera such as Geodermatophilus and Rubrobacter were found in both farms, although more were found in the low-yield one, whereas more Streptomyces were found in the high-yield farm. In addition, fungal alpha diversity was higher in the high-yield farm with the dominance of Sordariomycetes, Dothideomycetes, Eurotiomycetes, and Glomeromycetes.
Journal Article
Personal Protective Equipment Detection: A Deep-Learning-Based Sustainable Approach
by
Al-Qarawi, Seba
,
Youldash, Mustafa
,
Mhran, Afnan
in
Accuracy
,
Artificial intelligence
,
Construction
2023
Personal protective equipment (PPE) can increase the safety of the worker for sure by reducing the probability and severity of injury or fatal incidents at construction, chemical, and hazardous sites. PPE is widely required to offer a satisfiable safety level not only for protection against the accidents at the aforementioned sites but also for chemical hazards. However, for several reasons or negligence, workers may not commit to and comply with the regulations of wearing the equipment, occasionally. Since manual monitoring is laborious and erroneous, the situation demands the development of intelligent monitoring systems to offer the automated real-time and accurate detection of PPE compliance. As a solution, in this study, Deep Learning and Computer Vision are investigated to offer near real-time and accurate PPE detection. The four colored hardhats, vest, safety glass (CHVG) dataset was utilized to train and evaluate the performance of the proposed model. It is noteworthy that the solution can detect eight variate classes of the PPE, namely red, blue, white, yellow helmets, head, person, vest, and glass. A two-stage detector based on the Fast-Region-based Convolutional Neural Network (RCNN) was trained on 1699 annotated images. The proposed model accomplished an acceptable mean average precision (mAP) of 96% in contrast to the state-of-the-art studies in literature. The proposed study is a potential contribution towards the avoidance and prevention of fatal/non-fatal industrial incidents by means of PPE detection in real-time.
Journal Article
Survey of medical students to assess their knowledge and attitudes toward organ transplantation and donation
by
al-Marzuq, Abrar Y.
,
al-Muhammad, Ibrahim
,
al-Shammari, Ahmad S. Jawad
in
Adult
,
Analysis
,
Attitudes
2019
Kidney transplantation is the most preferred treatment modality for patients with
end-stage renal disease (ESRD). This study aims at understanding the awareness, attitudes, and
beliefs among the medical and nonmedical students. The study population consisted of 500
medical students and 39 nonmedical controls, who were surveyed using a reliable questionnaire
that examined their knowledge and attitudes. A 24-item self-administered questionnaire, which
assessed the levels of knowledge, attitude regarding organ donation with dichotomous scale and
demographic data were used. Of the 500 medical students who received the questionnaire, 376
(75.2%) with a mean age of 22.1 ± 2.5 years responded; 39% were male, 43.6% were Bahraini, and 32.2% were from Saudi Arabia, 51.3% were in Grades-5 and 6 and 58.8% resided in big
cities. The medical students had a highly positive attitude and great willingness toward organ
donation. Majority of them (75.3%) knew the treatment of ESRD, and 70.7% recognized
correctly that kidney transplantation is the optimal treatment for ESRD. However, only 10.4%
knew that it is performed in Bahrain since 1995. A total of 241 participants (64.3%) reported
positive attitude toward living kidney donation and 71.8% expressed their agreement to donation
after death. More than half (66.8%) believed that their religion permits organ donation, although
56.6% of the participants believed that there is a danger after donating a kidney. When compared
to nonmedical students, there was no statistically significant difference in the attitudes toward
living kidney donation (P = 0.823) or organ donation after death (P = 0.066)
Journal Article