62 research outputs found
Assessing Future Precipitation Patterns, Extremes and Variability in Major Nile Basin Cities: An Ensemble Approach with CORDEX CORE Regional Climate Models [Dataset]
No full textTable S1. The location of each station and their attributes in the NRB; Figure S1. (a) The Root mean square error (RMSE), and (b) The correlation coefficient for the six models and ENSEM before bias correction; Figure S2. (a) The Root mean square error (RMSE), and (b) The correlation coefficient for the six models and ENSEM after bias correction; Figure S3. The seasonal variation in precipitation for stations (Addis Ababa, Asmara, Cairo, and Dodoma), before BC (left) and after BC (right); Figure S4. as S3 but for stations (Gitega, Juba, Kampala, and Khartoum), before BC (left) and after BC (right); Figure S5. as S3 but for stations (Kigali, Kinshasa, and Nairobi), before BC (left) and after BC (right); Table S2. The relative change in precipitation for the first period (2041–2060) and the second period (2081–2100) under RCP2.6 and RCP8.5 scenarios; Figure S6, Time-series plot of precipitation for (a) Addis Ababa, (b) Asmara, (C) Cairo, (d) Dodoma, (e) Gitega, (f) Juba, and (g) Kampala; Figure S7, Time-series plot of precipitation for (h) Khartoum, (i) Kigali, (j) Kinshasa, and (k) Nairobi; Table S3. The relative change in RX1Day and RX5Day for each station under RCP2.6 and RCP8.5 scenarios for mid-future (2041–2060) and far-future (2081–2100); Table S4. The relative change in CWD and CDD for each station under RCP2.6 and RCP8.5 scenarios for mid-future (2041–2060) and far-future (2081–2100).Peer reviewe
Assessing Future Precipitation Patterns, Extremes and Variability in Major Nile Basin Cities: An Ensemble Approach with CORDEX CORE Regional Climate Models
No full text© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Understanding long-term variations in precipitation is crucial for identifying the effects of climate change and addressing hydrological and water management issues. This study examined the trends of the mean and four extreme precipitation indices, which are the max 1-day precipitation amount, the max 5-day precipitation amount, the consecutive wet days, and the consecutive dry days, for historical observations (1971–2000) and two future periods (2041–2060/2081–2100) under RCP2.6 and RCP8.5 emission scenarios over the Nile River Basin (NRB) at 11 major stations. Firstly, the empirical quantile mapping procedure significantly improved the performance of all RCMs, particularly those with lower performance, decreasing inter-model variability and enhanced seasonal precipitation variability. The Mann–Kendall test was used to detect the trends in climate extreme indices. This study reveals that precipitation changes vary across stations, scenarios, and time periods. Addis Ababa and Kigali anticipated a significant increase in precipitation across all periods and scenarios, ranging between 8–15% and 13–27%, respectively, while Cairo and Kinshasa exhibited a significant decrease in precipitation at around 90% and 38%, respectively. Wet (dry) spells were expected to significantly decrease (increase) over most parts of the NRB, especially during the second period (2081–2100). Thereby, the increase (decrease) in dry (wet) spells could have a direct impact on water resource availability in the NRB. This study also highlights that increased greenhouse gas emissions have a greater impact on precipitation patterns. This study’s findings might be useful to decision makers as they create NRB-wide mitigation and adaptation strategies to deal with the effects of climate change.This research was funded by the Postdoctoral Joint Program between the Academy of Scientific Research and Technology (ASRT)/The Bibliotheca of Alexandria (BA), grant number 1270. “The APC was funded by Earth Science Institute v.v.i. of Slovak Academy of Science”.Peer reviewe
An Optimization Approach of IoD Deployment for Optimal Coverage Based on Radio Frequency Model
No full textRecently, Internet of Drones (IoD) has garnered significant attention due to its widespread applications. However, deploying IoD for area coverage poses numerous limitations and challenges. These include interference between neighboring drones, the need for directional antennas, and altitude restrictions for drones. These challenges necessitate the development of efficient solutions. This research paper presents a cooperative decision-making approach for an efficient IoD deployment to address these challenges effectively. The primary objective of this study is to achieve an efficient IoD deployment strategy that maximizes the coverage region while minimizing interference between neighboring drones. In deployment problem, the interference increases as the number of deployed drones increases, resulting in bad quality of communication. On the other hand, deploying a few drones cannot satisfy the coverage demand. To accomplish this, an enhanced version of a concise population-based meta-heuristic algorithm, namely Improved Particle Swarm Optimization (IPSO), is applied. The objective function of IPSO is defined based on the coverage probability, which is primarily influenced by the characteristics of the antennas and drone altitude. A radio frequency (RF) model is derived to evaluate the coverage quality, considering both Line of Sight (LOS) and Non-Line of Sight (NLOS) down-link coverage probabilities for ground communication. It is assumed that each drone is equipped with a directional antenna to optimize coverage in a given region. Extensive simulations are conducted to assess the effectiveness of the proposed approach. Results demonstrate that the proposed method achieves maximum coverage with minimum transmission power. Furthermore, a comparison is made against Collaborative Visual Area Coverage Approach (CVACA), and a game-based approach in terms of coverage quality and convergence speed. The simulation results reveal that our approach outperforms both CVACA and the gamebased schemes in terms of coverage and convergence speed. Comparisons validate the superiority of our approach over existing methods. To assess the robustness of the proposed RF model, we have considered two distinct ranges of noise: range1 spanning from -120 to -90 dBm, and range2 spanning from -90 to -70 dBm for different numbers of UAVs. In summary, this research presents a cooperative decision-making approach for efficient IoD deployment to address the challenges associated with area coverage and achieves an optimal coverage with minimal interference.This research was funded by Project Number INML2104 under the Interdisciplinary Center of Smart Mobility and Logistics at King Fahd University of Petroleum and Minerals. This study also was supported by the Special Research Fund BOF23KV17.
Authors at KFUPM would like to acknowledge the support received under University Funded Grant # INML2300. The author at Hasselt University acknowledges the support received from Special Research Fund (BOF) under Grant # BOF23KV17
IoD swarms collision avoidance via improved particle swarm optimization
No full textDrones flights have been investigated widely. In the presence of high density and complex missions, collision avoidance among swarm of drones and with environment obstacles becomes a challenging task and indispensable. This paper aims to enhance the optimality and rapidity of three dimensional IoD path generation by improving the particle swarm optimization (PSO) algorithm. The improvements include using chaos map logic to initialize the population of PSO. Also, adaptive mutation is utilized to balance local and global search. Then, the inactive particles are replaced by new fresh particles to push the solution toward global optimal. Furthermore, Monte Carlo simulation is carried out and the results are compared with slandered PSO and with recent work CIPSO. The results exhibit significant improvement in convergence speed as well as optimal solution which prove the ability of proposed method to generate safety path for IoD formation without collision with terrain obstacle and among drones.The authors would like to acknowledge the support of the department of the computer engineering at King Fahd University of Petroleum and Minerals for this work.Ahmed, G (corresponding author), King Fahd Univ Petr & Minerals, Comp Engn Dept, Dhahran, Saudi Arabia.
[email protected]; [email protected]; [email protected]; [email protected]
Future Implications of Climate Change on Arum palaestinum Boiss: Drought Tolerance, Growth and Production
No full textThe objectives of the work were to understand the potential future climate changes in the Mediterranean region, assess the drought tolerance of the black calla lily (Arum palaestinum Boiss.), and investigate the mechanisms associated with its ability to withstand drought conditions. The Shared Socioeconomic Pathways (SSPs) of the Intergovernmental Panel on Climate Change (IPCC) were used to predict future temperature and precipitation changes. Both the SSP2-4.5 and SSP5-8.5 scenarios predicted a general increase in minimum and maximum temperatures and a decrease in precipitation. The projected increase in minimum temperature ranged from 2.95 °C under SSP2-4.5 to 5.67 °C under SSP5-8.5. The projected increase in maximum temperature ranged from 0.69 °C under SSP2-4.5 to 3.34 °C under SSP5-8.5. The projected decrease in precipitation ranged from −1.04 mm/day under SSP2-4.5 to −1.11 mm/day under SSP5-8.5. Results indicated that drought significantly impacted the physiological responses of the black calla lily. As drought increased, the black calla lily showed a reduction in leaf characteristics and non-structural carbohydrates, while proline content and reducing sugar content were increased, enhancing drought tolerance through osmoregulation. The black calla lily tolerates drought at a total ET of up to 50%. It has the potential to adapt to expected climate change through osmoregulation or by building a carbon and nitrogen sink for stress recovery
Modelling the Shear Behavior of Short Columns under Single Curvature
No full textShort concrete columns are the structural members dominated with nonlinear strains distribution (D region), and they are characterized with small shear span to depth ratios. Since short columns fail in brittle shear pattern, they can not be modelled using the plane -sections-remain-plane hypothesis (beam theory). Therefore, this thesis introduces an effective and simple approach to model such members by applying the modified 3PKT theory which is originally based on a three-degree-of-freedom kinematic model for the deformation patterns in walls. This research also focuses on verifying the ability of non-linear finite element software (VecTor2) to capture the responses behaviour of short columns and compare the FEA results with both experimental and 3PKT results. Several experimental studies on short reinforcement concrete columns have been filtered to only three series of experimental studies to be placed as a test database which is applicable for the scope of the project. The series specimens are having either rectangular or square sections and their experimental test setup is a single beam configuration with aspect ratios smaller than approximately 3.0. Then, the specimens have been modeled using the two tools (3PKT-VecTor2). The results showed that both approaches successfully predicted the shear behavior of the specimens. The resulted peak load experimental to predicted ratios of VecTor2 and 3PKT approaches have a mean value of 0.87 and 0.98 with a coefficient of variation of 7.58% and 6.78 % respectively.Short concrete columns are the structural members dominated with nonlinear strains distribution (D region), and they are characterized with small shear span to depth ratios. Since short columns fail in brittle shear pattern, they can not be modelled using the plane -sections-remain-plane hypothesis (beam theory). Therefore, this thesis introduces an effective and simple approach to model such members by applying the modified 3PKT theory which is originally based on a three-degree-of-freedom kinematic model for the deformation patterns in walls. This research also focuses on verifying the ability of non-linear finite element software (VecTor2) to capture the responses behaviour of short columns and compare the FEA results with both experimental and 3PKT results. Several experimental studies on short reinforcement concrete columns have been filtered to only three series of experimental studies to be placed as a test database which is applicable for the scope of the project. The series specimens are having either rectangular or square sections and their experimental test setup is a single beam configuration with aspect ratios smaller than approximately 3.0. Then, the specimens have been modeled using the two tools (3PKT-VecTor2). The results showed that both approaches successfully predicted the shear behavior of the specimens. The resulted peak load experimental to predicted ratios of VecTor2 and 3PKT approaches have a mean value of 0.87 and 0.98 with a coefficient of variation of 7.58% and 6.78 % respectively
The Possible Impacts of Different Global Warming Levels on Major Crops in Egypt
No full textClimate change implications are a severe risk to food security and the economy. Global warming could disturb the production of both rainfed and irrigated agriculture thru the amplify of yield water requests in many areas. In this study, the fast-track projections available through the Inter-Sectors Impact Model Intercomparison Project (ISI-MIP) were presented and analyzed to assess the effects of two global warming (GW) levels (1.5 and 2.0 °C) on the maize and wheat yields in Egypt. Outcomes proposed spatial variations in the effects of temperature change on crop yield. Compared with the referenced situation, an observed national average change in wheat yield about 5.0% (0.0% to 9.0%) and 5.0% (−3.0% to 14.0%) under GW1.5 and GW2.0 respectively. While for maize yield, the change in national average about −1.0% (−5.0% to 3.0%) and −4.0% (−8.0% to 2.0%) under GW1.5 and GW2.0 respectively. GW1.5 could be helpful for wheat yield, but the positive effect decayed when the warming level reached 2.0 °C overhead the pre-industrial level. Nevertheless, the possible deviations to Egypt’s maize production under the GW1.5 and GW2.0 scenarios are unclear where the models do not agree with the sign of change. Adjusting the temperature rise within 1.5 °C would diminish the yield reduction, as it is an extraordinary priority to safeguard crop production. To achieve Progress of innovative agronomic managing plans and swapping to additional drought-resistant crops may be valuable for coping with climate change in regions vulnerable to yield decline
CLINICAL PATTERNS AND OUTCOMES IN CIRRHOTIC YEMENI PATIENTS WITH ACUTE-ON-CHRONIC LIVER FAILURE
No full textفشل الكبد الحاد على المزمن (ACLF) هو حالة سريرية تتمثل في تفاقم مفاجئ لوظائف الكبد لدى مرضى الأمراض الكبدية المزمنة، ويرتبط بفشل الأعضاء خارج الكبد وزيادة معدل الوفيات. هدفت هذه الدراسة إلى تحديد الأنماط السريرية والنتائج المترتبة على مرضى تليّف الكبد اليمنيين المصابين بالفشل الكبدي الحاد على المزمن. أُجريت هذه الدراسة الوصفية المستقبلية على 160 مريضاً بالتليف الكبدي تم إدخالهم بين مايو 2023 ومايو 2024 إلى قسم الطب الباطني في مستشفى الصداقة التعليمي العام في عدن. بناء على معايير الجمعية الأوربية لدراسة أمراض الكبد: تم تقسيم المرضى إلى: المجموعة الأولى شملت 54 مريضًا بتليف كبدي يعانون من الفشل الكبدي الحاد على المزمن، والمجموعة الثانية شملت 106 مريضا بتليف كبدي لا يعانون من الفشل الكبدي الحاد على المزمن. نسبة انتشار الفشل الكبدي الحاد على المزمن كانت 33.8%. كان متوسط العمر 41.54± 8.11 سنة في مرضى الفشل الكبدي الحاد على المزمن و39.22± 8.14 سنة في المرضى غير المصابين بالفشل الكبدي الحاد على المزمن. كانت نسبة الذكور في مجموعة الفشل الكبدي الحاد على المزمن 51.9% مقابل 57.5% في المرضى غير المصابين. كانت الأسباب الأكثر شيوعاً للتليف الكبدي هي مجهولة السبب (58.8%) والتهاب الكبد المناعي الذاتي (25.6%). وُجدت علاقة ذات دلالة إحصائية بين سوابق الإدخال للمستشفى وتفاقم الكبد الحاد، في زيادة خطر تطور الفشل الكبدي الحاد على المزمن. كانت المضاعفات الأكثر شيوعاً هي اليرقان، والغيبوبة الكبدية، والقصور الكلوي، وعلامات العدوى البكتيرية، والاستسقاء، ونزيف الجهاز الهضمي. كانت العوامل الرئيسية المسببة للفشل الكبدي الحاد على المزمن هي العدوى البكتيرية، وخاصة التهاب الصفاق البكتيري (48.1%)، نزيف الجهاز الهضمي (24.1%)، وعدم وجود عوامل مسببه معروفة (24.1%). كانت حالات الفشل العضوي الأكثر شيوعاً هي الفشل الكلوي (70.4%)، فشل الكبد (42.6%)، والفشل الدماغي (31.5%). أظهر مرضى الفشل الكبدي الحاد على المزمن مستويات أعلى من كريات الدم البيضاء، البيليروبين، والكرياتينين في المصل. كانت معدلات الوفيات أعلى بشكل ملحوظ في مرضى الفشل الكبدي الحاد على المزمن مقارنة بالمرضى غير المصابين، على كلا الفترتين 28 يوماً (33.3% مقابل 5.7%) و90 يوماً (68.5% مقابل 23.6%). تظهر هذه الدراسة أن مرضى الفشل الكبدي الحاد على المزمن لديهم توقعات أسوأ، معدلات وفيات أعلى، دخول أكبر لوحدات العناية المركزة، بقاء أقل، ومعدلات أعلى لفشل الأعضاء مقارنة بالمرضى غير المصابين بالفشل الكبدي الحاد على المزمن.Acute-on-chronic liver failure (ACLF) is a clinical condition of abrupt hepatic decompensation in chronic liver disease patients that is associated with extra-hepatic organ failures and a higher mortality rate. This study aimed to identify the clinical patterns and outcomes in cirrhotic Yemeni patients with ACLF. This prospective cohort study was carried out on 160 cirrhotic patients admitted between May 2023 and May 2024 to the Internal Medicine Department in Al-Sadaqah General Teaching Hospital in Aden governorate, Yemen. Based on the European Association for Study of Liver's Chronic Liver Failure Consortium EASL-CLIF criteria, patients were divided into Group A: 54 patients with ACLF. Group B: 106 patients without ACLF. The prevalence of ACLF is 33.8%. The mean age was 41.54± 8.11 years in ACLF and 39.22± 8.14 years in non-ACLF patients. The proportion of males in ACLF was 51.9% vs. 57.5% in non-ACLF patients. The most common causes of cirrhosis were cryptogenic (58.8%) and autoimmune hepatitis (25.6%). A significant correlation was found between prior hospitalization, decompensation, and the increased risk of developing ACLF. The most common complications were jaundice, hepatic encephalopathy, renal failure, signs of bacterial infection, ascites, and gastrointestinal bleeding, respectively. The main precipitating events for ACLF were bacterial infection, especially SBP (48.1%), GIT bleeding (24.1%), and no identified precipitating events (24.1%). The most common organ failures were renal (70.4%), liver (42.6%), and cerebral (31.5%). ACLF patients showed higher levels of WBCs, bilirubin, and serum creatinine. Mortality rates were significantly higher in ACLF patients compared to non-ACLF at both 28 days (33.3% vs. 5.7%) and 90 days (685% vs. 23.6%). This study demonstrated that ACLF patients have worse prognoses, higher mortality rates, increased ICU admission, lower survival, and higher rates of organ failure than non-ACLF patients
Efficient Modeling of Complex Sandy Coastal Evolution at Monthly to Century Time Scales
No full textWith large-scale human interventions and climate change unfolding as they are now, coastal changes at decadal timescales are not limited to incremental modifications of systems that are fixed in their general geometry, but often show significant changes in layout that may be catastrophic for populations living in previously safe areas. This poses severe challenges that are difficult to meet for existing models. A new free-form coastline model, ShorelineS, is presented that is able to describe large coastal transformations based on relatively simple principles of alongshore transport gradient driven changes as a result of coastline curvature, including under highly obliquely incident waves, and consideration of splitting and merging of coastlines, and longshore transport disturbance by hard structures. An arbitrary number of coast sections is supported, which can be open or closed and can interact with each other through relatively straightforward merging and splitting mechanisms. Rocky parts or structures may block wave energy and/or longshore sediment transport. These features allow for a rich behavior including shoreline undulations and formation of spits, migrating islands, merging of coastal shapes, salients and tombolos. The main formulations of the (open-source) model, which is freely available at www.shorelines.nl, are presented. Test cases show the capabilities of the flexible, vector-based model approach, while field validation cases for a large-scale sand nourishment (the Sand Engine; 21 million m3) and an accreting groin scheme at Al-Gamil (Egypt) show the model’s capability of computing realistic rates of coastline change as well as a good representation of the shoreline shape for real situations.Coastal Engineerin
Assessment of human interventions presence and their impact on shoreline changes along Nile delta, Egypt
No full textCoastal erosion is a natural process, that contributed to shaping the Nile Delta shoreline in Egypt over history. The objective of this research is to investigate shoreline changes, accretion, and erosion and to detect particularly vulnerable locations that require immediate attention. Another goal is to assess the efficiency of coastal installations that have been recently implemented along the study area and determine whether they have performed their role to the fullest or need additional modifications. Several Landsat images (TM, ETM+, and OLI) were utilized over 37 years to track the shoreline changes and were analysed using remote sensing (RS) and Geographic Information System (GIS). The digital shoreline analysis system (DSAS) was integrated with the LRR model for assessing historical changes for shorelines from 1985 to 2022 and forecasting future shoreline positions in 2030, 2050, and 2100. Most of the eight zones that make up the Delta region have lately seen the establishment of coastal projects, such as the development of the Abu Qir port's breakwater in 2021. From the results, it was found that the areas around Rosetta promontory, Burullus headland, and Damietta promontory experienced a significant and rapid retreat and with large rates over the study period, with average values of –15.7, –3.25, and –16.8 m/y, respectively. However, both the coast of Alexandria, and Gamasa embayment were subjected to accretion as a prevailing case, with average rates of 2.85, and 4.03 m/y, respectively. Many groins were installed in the east of the Rosetta promontory (zone 3) in 2016 to decrease the erosion process; however, it didn't pay off and could not solve the problem. In contrast, the groins system, which was implemented at the East Kitchener Drain (zone 5) in the same year, lowered erosion rates from 17.6 m/y from 2000 to 2010 to 7 m/y from 2010 to 2022. In 2019, Y-groins built in zone 7, east of Damietta Port, succeeded in slowing rates of erosion. Finally, inlet jetties at El-Gamil (zone 8) were constructed in 2016, resulting in the coastline advancing at 14.7 m/y on average in the period of 2010–2022. The findings of this study confirmed that hard structures are dangerous because they exacerbate the problem of shoreline erosion by disseminating it to the neighbouring beaches and acting as an impediment to the movement of longshore sediments. According to the expected future shoreline patterns, it is necessary for authorities to implement both short-term and long-term protective measures to stop the erosion of several areas of the beach
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