193 research outputs found
Site-specific ground motion modeling for a historical Cairo site as a step towards computation of seismic input at cultural heritage sites
No full textThroughout time, the area of historical Cairo has been affected by several earthquakes from near and distant seismogenic zones. The maximum earthquake intensity reported in Cairo is VII, on the Modified Mercalli Intensity scale, due to the 1992 Cairo earthquake (Mw=5.9). About 212 Coptic and Islamic monuments were damaged. The spatial distribution of damage, suggests the occurrence of strong local site effects in combination with high vulnerability of the cultural heritage buildings. This study presents the application of a novel seismic hazard analysis approach at a local scale based on physics-based ground motion simulations. A site-specific multi-scenario seismic input (ground motion time histories and response spectra) is computed at a heritage building in Cairo, considering the local site effect. The seismic input is calculated in three steps: a regional scale analysis followed by a site-specific analysis and the combinations of the computed scenarios ground motion. In the regional scale analysis synthetic accelerograms are computed at the site bedrock. Then, the site-specific analysis is performed to calculate the site surface ground motions or response spectra considering the local site effect. Three earthquake scenarios have been considered, characterized by different locations, magnitudes, and fault configurations. The last step consists in the combination of the computed scenario ground motion into one single multi-scenario seismic input specific for the site of interest. This input is represented by spectral ordinates and their variability. For the engineering purpose of time history analysis, the method allows also to extract the computed site specific physics-based accelerograms, requiring no amplitude scaling nor filtering by magnitudes, distances, or site classifications, as usually done with real ground motion records
Polyphenolic profile, hepatoprotective evaluation, and molecular docking study of three palm tree species (Family Arecaceae)
No full textArecaceae species are renowned in traditional medicine for treating inflammation and liver disorders. Herein, we aimed to identify the phenolic constituents and the hepatoprotective potential of the aqueous methanol extract (AME) of Aiphanes
eggersii, Carpoxylon macrospermum, and Jubaeopsis caffra leaves, in a drug-induced liver injury in vivo model. The AMEs are considered safe until the maximum tested dose (5 g/kg). The two selected screening doses, 500 and 1000 mg/kg, displayed antioxidant activity with significant (P < 0.05) decline in the liver/body weight ratios (19.1–29.7%), liver enzymes (25.9–63.4%), and malondialdehyde (39.3–63.8%), while increasing reduced glutathione (2.1–3.2 folds) and superoxide
dismutase (2.2–3.1 folds). Moreover, they demonstrated a significant anti-inflammatory effect (P < 0.05) with decline in NF-KB p65 (32.7–64.5%), tumor necrosis factor-alpha (24.9–64.4%), and interleukin-1β (18.7–64.2%). Ultimately, significant (P < 0.05) antiapoptotic effects from the declined BAX (31.8–65.6%) and caspase-3 (23–69%), while increasing Bcl2 (2.7–5.7 folds). Ultimately, the histopathological investigation showed obvious hepatoprotective efficacy. The HPLC–MS/MS profiling revealed high phenolic content. As key phenolic attributes, chlorogenic acid is major in C. macrospermum and J. caffra, while vanillic in A. eggersii. Rutin is the principal flavonol in the three extracts (365.852–57970.205 μg/Kg), followed by hyperoside (62.764–7379.297 μg/Kg) and hesperidin (1225.976–1575.550 μg/Kg). The docking results show that rutin and hesperidin achieved the best fitting to SOD-1, with binding scores of -8.24 and -8.36 kcal/mol, while -8.0671
and -7.1735 kcal/mol with caspase-3, respectively with stable conformations revealed by 100 ns MD. In all, the investigated species exert significant hepatoprotective activity, at least partly, to their constitutive flavonoids and phenolic acids. However, further clinical investigation is still needed
The performance enhancement of solar cooker integrated with photovoltaic module and evacuated tubes using ZnO/Acalypha Indica leaf extract: response surface study analysis
No full textIn this study, the effect of employing ZnO/Acalypha Indica leaf extract (ZAE) on the energy absorption of a coated portable solar cooker has been examined using an experimental setup. A prototypical model has been developed to corroborate in associating an investigative outcome per constituents of the experiments. The studied heat transfer process in ZAE is stable for harsh conditions. The design analysis and an estimation of the system performance were done given various parameters including the pressure of the vacuum envelope, bar plate coating digestion, emissivity, and solar rays. The fabricated solar was tested with and without ZAE to investigate the impact of this coating material on the solar cooker's thermal performance. To observe the performance of the new design, two figures of merit (F-1 and F-2) have been introduced. The factual food cooking assessments were for a family of four people, which operated in ZAE coating (0.8, 1.0, 1.2 mu m) of the solar cooker. The values of F-1 and F-2 for the proposed cooker were obtained as 0.1520 and 0.4235, respectively, which is intact with the BIS values. The results revealed that employing ZAE instead of a thermal NHC-PV solar cooker reduced the time required to boil 2 L of water for about 47 min. The overall thermal energy productivity of the solar cooker with electrical backup was obtained as 42.65%, indicating that the ZAE coating can improve the thermal efficiency by 10.35%
Correction: Guidelines for the prevention, detection and management of the renal complications of COVID-19 in Africa
No full textThe authors of the article ‘Guidelines for the prevention, detection and management of the renal complications of COVID-19 in Africa’ [1] wish to acknowledge the contribution of Professor Hussein El Fishawy. Our guidelines drew on various sources, including the Egyptian Ministry of Health guidelines, portions of which were adapted and reproduced with permission from the Egyptian Ministry of Health. Two of the authors of those guidelines, Professors Elsayed and Zaki, are also coauthors of our paper. Professor El Fishawy was the third author of the Egyptian guidelines and we would like to acknowledge his contribution to our review through this source, especially with respect to the treatment algorithms for patients with kidney transplants and those with acute kidney injury. Reference1. Elsayed HM, Wadee S, Zaki MS, Were AJO, Ashuntantang GE, Bamgboye EL, et al. Guidelines for the prevention, detection and management of the renal complications of COVID-19 in Africa. Afr J Nephrol. 2020; 23(1):109-126
Reliability estimation of balanced systems with multi-dimensional distributed units
No full textBalanced systems with multi-dimensional distributed units are emerging in a diverse range of industries. This includes Unmanned Aerial Vehicles (UAV) with multi-level of rotary wings, Spherical Unmanned Vehicles (SUV), Spherical Phased Array Antenna (SPAA), etc. In this dissertation, we present the reliability estimation for such systems. In particular, we consider two configurations: 1) balanced systems with units distributed circularly on multi-level and 2) balanced systems with units distributed spherically.
First, balanced systems with units distributed circularly on multi-level are generalized as (k₁, k₂)-out-of-(n, m) pairs: G balanced systems. We consider two scenarios: 1) all units perform the same function and 2) adjacent pairs perform complementary functions. For both scenarios, unbalanced system is considered as failed. When units fail and cause the system imbalance, we explore two approaches to rebalance the system: 1) forcing down units on other locations and 2) resuming units that are previously forced down (if any). When units in a system perform the same function, operational states are defined as balanced states with at least k₁ operating pairs and each operating pair has at least k₂ units on each side. The system reliability is obtained by enumerating all of the operational states and summing the probabilities of those states. For (k₁, k₂)-out-of-(n, m) pairs: G balanced systems with adjacent pairs performing complementary functions, in addition to maintaining system balance, the adjacent operating pairs are required to perform complementary functions. Thus, if a pair fails, one of the adjacent pairs is forced down. Similarly, the system reliability is obtained by enumerating all of the operational states. It becomes computational expensive when the number of units in each pair and/or the number of pairs are large. In that case, efficient algorithms are developed to obtain the reliability for such systems.
The balanced system with units distributed spherically is generalized as a spherical k-n-i: G balanced system. We consider two balancing requirements: 1) rotational balance is maintained so that the system is not rotating w.r.t. roll, yaw and pitch axes and 2) symmetrical balance is essential in improving the systems’ stability. We present mathematical approaches to determine the balance status of a system. Similarly, the unbalanced system is rebalanced by 1) forcing down units on other locations and 2) resuming previously forced-down units. The system reliability is obtained by the enumeration of operational states and calculation of operational states’ probabilities. We develop an efficient algorithm for reliability estimation when the number of units in the system is large.
Degradation models are developed for the (k₁, k₂)-out-of-(n, m) pairs: G balanced systems to further investigate the system reliability when degradation data are available. The degradation processes of units in the system are either stationary (inverse Gaussian process) or non-stationary (improved inverse Gaussian process). We propose a degradation balance mechanism in which the ‘most’ degraded units are forced down temporarily during the degradation process so that the system is less possible to fail due to imbalance. A closed-form lower bound reliability is presented when the balance mechanism is not applied. When it is applied, reliability is obtained by Monte Carlo simulation.
From the reliability study of the both configurations, it is observed that the reliability of a balanced system with multi-dimensional distributed units depends not only on the system’s total number of units and the least number of operating units, but also on the system configurations and balance requirements. Systems with more units do not necessarily provide a higher reliability since they are more likely to fail due to imbalance. Thus, optimal system design is key to maximize the system reliability which is investigated through numerical examples in this dissertation.Ph.D.Includes bibliographical reference
The Impact of Low-Power Design Methodology on Digital Libraries
No full textIn recent years, exciting new low-power design methods have been introduced, such as: multiple supply voltages, body bias techniques and power shut-off. In order to use these low power design methods, strict requirements for both libraries and tools are needed. An additional challenge is the introduction of more accurate characterization models for newer technologies (current source models like ECSM and CCS). This has made the task of library checking a serious issue that needs to be automated. The main part of this thesis presents a checker tool that is used to verify the consistency of the different library formats (views) in standard cell libraries. The layout consistency checker in our tool checks the consistency of the layout of pins between GDSII and LEF library views; we devised a new algorithm,Grid Formation and Centre Inclusion, for this checker. The tool also verifies the pin consistency and availability of cells across other library formats, such as: Verilog and Liberty. The tool was tested using different technology libraries (such as 90nm and 40nm), provided by different vendors (such as GLOBALFOUNDRIES); multiple interfacing errors were caught using our library checker tool. A second part at the end of the thesis shows experiments with some of the low-power design techniques used during the design of a digital block, using -for implementation- standard cells from one of the libraries that have been checked with the library checker tool. Benefits of using these techniques are evaluated and trade-offs are discussed. Power-Shut Off (PSO) design technique proved to be the most effective in reducing power consumption, with power savings that reached 20%.Circuits and SystemsElectrical Engineering, Mathematics and Computer Scienc
Mapping and evaluating the condition of artificial levees
No full textArtificial levees along alluvial rivers are major components of flood risk mitigation. This is especially true in the case of Hungary, where more than one-third of the country is threatened by floods and protected by an over 2940-km-long levee system. Most of the levees were built in the 19th century. Since then, several natural and anthropogenic processes, such as compaction, erosion, Etc., could contribute to these earth structures' slow but steady deformation. Meanwhile, as construction works were scarcely documented, the structure and composition of artificial levees are not well known. Therefore, the present analysis aimed to use different geophysical techniques to validate their efficiency in mapping structural differences, possible compositional deficiencies, potential defects and sections where elevation decrease and compare the compositional and structural variations of two very different levee sections along a 24 km section of the River Tisza and a 24 km section of the River Maros. Investigations were conducted by real-time kinematic GPS (RTK-GPS), Ground penetrating radar (GPR), Electrical Resistivity Tomography (ERT) and drillings. Onsite data acquisition was complemented with an analysis using a Persistent Scatterer Synthetic Aperture Radar (PSI) to assess general surface deformation. The higher frequency 200 MHz GPR data have shown that levee structures can significantly vary even in a few km on sections with the same construction history.
Based on electrical resistivity tomography results with a precise analysis of grain size and their related physical parameters used for monitoring the materials of two different levee sections along the Tisza and Maros rivers, we noticed that the main components of investigated Tisza levee section are medium and fine silts, however, the situation of the investigated Maros levee section shows more variation of different materials which are fine, medium, and coarse silt, moreover, fine, medium, and coarse sand. The investigated section of the Tisza levee showed low resistivity values, indicating the fine-grained materials' conductivity. In contrast, the investigated section of the Maros levee showed high resistivity values, indicating the resistivity nature of higher grain size sediments forming this section, especially noticed on the protected side of the levee.
It was possible to capture structural changes and resolving the thin layers by 1 m electrode spacing ERT profile. In turn, at a larger spacing it was possible to get information on the sedimentary base below the levee body. The selected levee section could be assessed in terms of its structure and composition and major units within the levee body and their composition could be resolved by the applied methods.
In general, there is a similarity in the materials and their resistivity range which form the core of Tisza and Maros levees, however, the situation on their both sides is not the same. Regarding the analysis of different physical properties of the two levee systems like resistivity, porosity, density, water content, grain size, and saturated hydraulic conductivity, the materials of the Maros levee could be distinguished well and showed more variation when it is compared to the materials of Tisza levee. It means that the physical properties of levee materials are very important, and they are recommended when carrying out further levee investigations.
From the physical properties mentioned above, it was found that some of them show a connection with resistivity except hydraulic conductivity parameter that did not show a direct connection, however the latter could exhibit the aquitard nature of Tisza levee materials and the non-aquitard nature of Maros levee materials which illustrates the difference in levee composition in terms of flood risk or flood safety.
Based on height measurements, the mean elevation of the levee crown decreased by 8 cm in a 40-year time span. However, elevation decrease could reach up to 30 cm at some locations. Sections affected by structural anomalies, compositional changes, and increased surface subsidence are especially sensitive to floods when measurement results are compared to flood phenomena archives.
GPR profiles showed several anomalies, including structural and compositional discontinuities and local features. They were classified into six types regarding to the flood risk; tensile cracks (enables piping, leading to levee breach or mass failure, cracks might close when the levee gets wet), remarkable changes in dielectric permittivity (enables seepage, leading to mass failure), animal burrows (enables piping, leading to levee breach or mass failure), layer deformation (results in height decrease, overtopping), paleo river channel (enables seepage below the levee, leading to water upwelling and the development of sand boils), sudden change in stratification or dipping layers (enables contour line seepage, leading to mass failure). The penetration dept
Modeling and optimization of container inspection systems
No full textContainer inspection is vital to maintaining secure ports-of-entry and preventing undesired cargo from entering the United States. The inspection process can be generalized as the collection and analysis of information obtained from multiple sensors. Formulating a mathematical model of container inspection allows for evaluation and improvement of the process. The performance of the system under a specified policy is evaluated using one or more objectives such as misclassification errors (false accept and false reject), costs associated with these errors, inspection cost, inspection time, and others. The main contributions of this research are the modeling, formulation, and optimization of inspection policies under different conditions. Furthermore, the dissertation introduces a new class of problems in scheduling theory in which the allocation of inspections is not defined and appears as a decision variable in the solution. In the initial model, the overall system decision is a Boolean function of the individual station decisions. Under these conditions we define an optimal sequence of stations with respect to the expected cost of inspection and solve simultaneously for the threshold level values and sequence of stations that produce a minimum total cost. This optimization is extended to include the time for inspection as an objective and a multi-objective optimization approach is developed. Next we introduce an independent error term that accounts for measurement error contributed by the sensor and propose some strategies, including repeat inspection, to improve the system’s performance. We investigate an approach to approximating the efficient frontier for three objectives. We then consider distinct risk categories and due times for containers. Approaches are developed to determine the optimal allocation and scheduling of inspection operations to minimize false acceptance and tardiness objectives. The problem is presented as a variation of the open shop scheduling problem with no predefined operations. A solution approach to this simultaneous allocation and scheduling problem is proposed and its performance is compared with an enumerative approach. The results show that the proposed approach produces near-optimal solutions in a much shorter time than full enumeration and is capable of solving large problems for which the enumerative approach is intractable.Ph.D.Includes bibliographical referencesIncludes vitaby Christina M. Youn
Aggregation enhanced excimer emission (AEEE) with efficient blue emission based on pyrene dendrimers
No full textThe relationship between financial system development and economic growth in the egyptian economy
No full textOver the recent decades, there have been extensive theoretical and empirical debates on the relationship between finance and growth. However, the empirical results are ambiguous and vary according to the measures of financial development; function form; estimation method; and data frequency. Therefore, by using different time series techniques, this thesis investigated three different aspects but, nevertheless, interrelated dimensions of the finance-growth nexus in developing countries and, particularly, in the case of Egypt. Firstly, by using a Vector Error Correction Model (VECM) in which the banking sector and the stock market were modelled explicitly and simultaneously, we investigated the relationship and causality direction between financial development and
economic growth. The co-integrating vector showed that, rather than the banking sector, stock market development was more conducive to a higher rate of growth. Moreover,
the causality pattern showed that, whilst, in the long-run, there was a consistent causality pattern which supported the demand-following view, in the short-run, the
causality pattern provided mixed results. Secondly, based on McKinnon’s complementary hypothesis, we investigated the long-run and short-run association between financial liberalisation; financial development; interest rate behaviour; and savings and investment. On the one hand, the empirical findings indicated that McKinnon’s complementary hypothesis did not hold in the case of Egypt and, on the
other hand, financial development led to larger financial systems which contributed positively to savings; investment; and economic growth. However, financial
liberalisation had an adverse effect on savings and investment.
Finally, we evaluated the validity of the new structuralism hypothesis highlighting a dynamic relationship between country’s financial structure and the phase of economic
development. The main findings confirmed the new structuralism hypothesis. Financial structure is dynamic and determined endogenously by the demands from the real
economy for specific types of financial services. Consequently, particular types of financial system structures exist and are more effective than others in managing particular types of risk; matching savings with investment; promoting efficient allocation of resources; and spurring economic growth at particular points of time and stages of economic development. In the early stages of economic development, both the banks and the stock market are important. However, as the economic development advances, the stock market’s importance, relative to banking system, becomes more significant. Accordingly, the primary policy implication is that future financial policies
should strengthen the legal and institutional environment. This would enhance operational efficiency in the financial system and the allocation of capital resources. On the other hand, Policy-makers should encourage economic policies that repress the demand for money and speculation activities. In turn, these would spur investment and
the rate of economic growth. Furthermore, when designing the appropriate financial policy, policy-makers should take into consideration the level of economic development and the structure of the real economy since certain types of financial institutions and arrangements are better than others in serving particular industries
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