269 research outputs found
Estrateriga de dispersión de plantas en diferentes hábitats ecológicos de los Emiratos Árabes Unidos
Fecha de lectura de Tesis Doctoral: 18 de enero 2019Biología Vegetal (Botánica y Fisiología Vegetal)
Resumen tesis:
Estudio de las estrategias de dispersion de las especies vegetales en diferentes habitats del desierto de los Emiratos Arabes Unidos.
Se estudian las estrategias de dispersion de 307 especies y se relacionan con los principales caracteres funcionales relacionados con la supervivencia de especies en cinco ecosistemas aridos -deserticos.
Se estudia la relacion entre la forma de crecimiento de las especies vegetales y la presencia de baco aereo de semillas.
Se estudia el efecto de los regimenes de luz y temperatura que intervien en la dormancia y germinacion de Citrulus colocynthis, especie clave en el desierto de Arabi
On implementing dynamically reconfigurable architectures
Dynamically reconfigurable architectures have the ability to change their structure at each step of a computation. This dissertation studies various aspects of implementing dynamic reconfiguration, ranging from hardware building blocks and low-level architectures to modeling issues and high-level algorithm design. First we derive conditions under which classes of communication sets can be optimally scheduled on the circuit-switched tree (CST). Then we present a method to configure the CST to perform in constant time all communications scheduled for a step. This results in a constant time implementation of a step of a segmentable bus, a fundamental dynamically reconfigurable structure. We introduce a new bus delay measure (bends-cost) and define the bends-cost LR-Mesh; the LR-Mesh is a widely used reconfigurable model. Unlike the (idealized) LR-Mesh, which ignores bus delay, the bends-cost LR-Mesh uses the number of bends in a bus to estimate its delay. We present an implementation for which the bends-cost is an accurate estimate of the actual delay. We present algorithms to simulate various LR-Mesh configuration classes on the bends-cost LR-Mesh. For semimonotonic configurations, a Θ(N)*Θ(N) bends-cost LR-Mesh with bus delay at most D can simulate a step of the idealized N*N LR-Mesh in O((log N/(log D-log Δ))2) time (where Δ is the delay of an N-element segmentable bus), while employing about the same number of processors. For some special cases this time reduces to O(log N/(log D-log Δ)). If D=Nε, for an arbitrarily small constant ε \u3e 0, then the running times of bends-cost LR-Mesh algorithms are within a constant of their idealized counterparts. We also prove that with a polynomial blowup in the number of processors and D=Nε, the bends-cost LR-Mesh can simulate any step of an idealized LR-Mesh in constant time, thereby establishing that these models have the same power. We present an implementation (in VHDL) of the Enhanced Self Reconfigurable Gate Array (E-SRGA) architecture and perform a cost-benefit study for different dynamic reconfiguration features. This study shows our approach to be feasible
Performance of Isolated Footing with Several Corrosion Levels under Axial Loading
This research aims to illustrate the corrosion process and its effect on the deterioration of reinforced concrete (RC) isolated footings using a small-scale model (1/8) and present the results of a prototype-scale study using a numerical model with different concrete depths and corrosion levels under axial load. The experimental program consisted of testing five small-scale (1/8) model RC isolated footings under axial loading after subjecting them to accelerated corrosion tests with a constant current. The main variable in the small-scale sample test was the corrosion level. This study presents an experimental approach, using the constant current method and the finite element method (FEM) with the ABAQUS package, to examine its effect on the axial load behavior under different corrosion ratios, which were 0%, 4.21%, 9.11%, 24.56%, and 30.67%. On the prototype scale, the variables were the corrosion level and the RC depths of 300 mm, 400 mm, and 500 mm. The results indicated that the average deviation in ultimate load between the experimental and FEM outcomes for the small-scale was below 5.6%, while the average deflection deviation was 6.8%. Also, the study found that an increase in the depth of the RC footing and corrosion ratio led to a more pronounced impact of the cracking pattern in the concrete and corroded bars, as well as a greater difference in the failure load. The experimental results suggest that the proposed numerical model is accurate and effective. These findings have important implications for the evaluation of isolated footings affected by corrosion damage using FEM, and can help inform decisions related to their design and maintenance. The failure loads of non-corroded footings with different depths were compared with the ECP-203 provisions of the 2018 Egyptian Code, and how corrosion ratios can be simulated by numerical models. The percentage variation between the design loads by code and the numerical loads by ABAQUS for controlled footings with thicknesses of 300, 400, and 500 mm was found to be 73%, 80%, and 78%, respectively. Using the derived relationship, the equivalent corrosion ratio percentages were 23.8%, 20.2%, and 32%, respectively. Doi: 10.28991/CEJ-2023-09-06-011 Full Text: PD
Schema clustering and retrieval for multi-domain pay-as-you-go data intergration systems
A data integration system offers a single interface to multiple structured data sources.
Many application contexts (e.g., searching structured data on the web) involve the integration of large numbers of structured data sources.
At web scale, it is impractical to use manual or semi-automatic data integration methods, so a pay-as-you-go approach is more appropriate.
A pay-as-you-go approach entails using a fully automatic approximate data integration technique to provide an initial data integration system
(i.e., an initial mediated schema, and initial mappings from source schemas to the mediated schema),
and then refining the system as it gets used.
Previous research has investigated automatic approximate data integration techniques,
but all existing techniques require the schemas being integrated to belong to the same conceptual domain.
At web scale, it is impractical to classify schemas into domains manually or semi-automatically,
which limits the applicability of these techniques.
In this thesis, I present an approach for clustering schemas into domains without any
human intervention and based only on the names of attributes in the schemas. My clustering approach
deals with uncertainty in assigning schemas to domains using a probabilistic model.
I also propose a query classifier that determines, for a given keyword query, the most relevant domains to this query.
I experimentally demonstrate the effectiveness of my schema clustering and query classification techniques
Analysis of The Driving Forces of Urban Expansion in Luxor City by Remote Sensing Monitoring
Luxor in Egypt is a city of great historical importance, rich in archaeological sites and natural resources. To ensure sustainable development in Luxor city, it is essential to understand the driving forces of its growth. Both Geographic Information Systems (GIS) and satellite Remote Sensing (RS) were successfully used to evaluate these overall driving forces. This paper is aimed at monitoring the growth dynamics of the urbanization process that occurred in Luxor city during a 20-year period from 1996 to 2017. The archived time series medium resolution Landsat ETM+ and TM satellite imagery are used to study and analyze spatial patterns of urban in order to improve understanding the impact of driving forces of urban expansion in Luxor. The GIS was not only used to identify the driving forces but also to provide an integrated monitoring of the study area. This offered a unique advantage to simultaneously store and manipulate spatial and attribute data of a large amount. A very significant increase in urban area has taken place in the last decade in Luxor city, which was revealed an important outcome. A net increase of 36.7 km2 was witnessed in the last 20 years (especially in recent years), in the built-up urban area. The built-up urban area in 2017 saw an increase that was twice that in 1996, with an annual average increase of 1.75 km2, and an annual change rate of 4.6%. The analysis of this dramatic change revealed that city infrastructure, economic growth, population growth, topographic elements, and city planning, and policies were the major driving forces for the rapid expansion of built-up urban area, albeit with different weights for these different forces. In this study, we explored a method of monitoring parameters related to the architectural heritage of Luxor governorate using “remote sensing big data†to provide data support for the city’s urban planning and policy formulation
Resonance Two Photon Ionization Study of Binary Clusters of Styrene with Polar Molecules
One-color resonance two-photo ionization (R2PI) spectra of mixed clusters of styrene molecule (S) with polar molecules [water (W), methanol (M), ethanol (E), and trifuoroethanol (T)] were measured through the S1←S0 transition of the styrene molecule. The spectra reveal a rapid increase in complexity with the number of polar molecules in the cluster, associated with van der Waal modes and isomeric forms. The spectral shifts of the cluster origins from the S1-S0 transition of the bare styrene molecule reflect the nature of the intermolecular interactions within the binary clusters. The obtained R2PI spectra xv were compared with the spectra of the analogous benzene containing clusters. The styrene-water and the styrene-methanol complexes exhibited very different spectral shifts and structures as compared to the benzene-water and benzene-methanol complexes, respectively. The favorable interactions of polar molecules with the olefin group of styrene may explain the strong inhibition effects of exerted by small concentrations of water and alcohols on the cationic polymerization of styrene. Size-specified intracluster proton transfer reactions were observed for mixed clusters of styrene dimer with water, methanol and ethanol molecules. It was proposed that the polar molecules tend to aggregate around the olefin center, which promotes the transfer of the charge from the propagating chain to the hydrogen-bonded polar molecules subcluster. The minimum number of polar molecules required for a proton transfer to take place exothermically depends on the proton affinity of the polar molecules subcluster. The estimated upper limit value for the proton affinity of styrene dimer radical was evaluated based on the energetic of the proton transfer reaction to be ≤ 220.4 kcal/mol. No intracluster reaction was observed for styrene-trifluoroethanol (STn) system. In order to provide a comparison between the styrene and benzene systems, the benzene-ethanol (BEn) and benzene-trifluoroethanol (BTn) clusters were studied by using the R2PI technique via the 6¹0 transition of the benzene molecule. Both dissociative electron transfer and dissociative proton transfer reactions were observed within the BEn clusters, where n = 2 and 3, respectively. Proton transfer reactions were observed following dissociative electron transfer reactions within the (BTn) clusters, where n = 4, to generate the protonated clusters (H+Tn)
Role of N-terminal pro B-type natriuretic peptide in acute exacerbation of chronic obstructive pulmonary disease
AbstractObjectivesAcute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a major public health problem. Recognition of comorbid heart dysfunction in such patients is often difficult. The aim of this work is to evaluate the role of N-terminal pro B-type natriuretic peptide (Nt-pro BNP) in AECOPD with respiratory failure.Patients and methodsThis study was conducted on 20 patients with AECOPD and respiratory failure. All patients were subjected to history taking, clinical examination, routine laboratory investigations, arterial blood gases analysis, echocardiography and estimation of plasma level of NT-pro BNP.ResultsPatients were classified into 3 groups: Group I: those without heart dysfunction (40%), Group II: those with diastolic heart failure (40%), and Group III: those with systolic heart failure (20%). NT-pro BNP mean±SD in group I was 673.38±416.02, in group II 1962±847.88, and in group III 6776.75±1433.59pg/ml. There was a statistically significant difference between the three groups (p=0.001). NT-pro BNP showed a statistically significant inverse correlation with pH (p=0.005), ejection fraction (p=0.007) and a direct one with both left ventricular systolic (p=0.008) and diastolic (p=0.016) dimensions and E/A (p=0.016). The NT-pro BNP significantly decreased after recovery from AECOPD (p=0.030). The receiver operating characteristic curve demonstrated a ruling out of LV dysfunction in AECOPD of a sensitivity of 100% and a specificity of 60%; and a ruling in of a sensitivity of 48% and a specificity of 67%.ConclusionPlasma BNP is usually elevated in AECOPD and is related to right or left ventricular systolic or diastolic dysfunction
Path Planning for a 6 DoF Robotic Arm Based on Whale Optimization Algorithm and Genetic Algorithm
The trajectory planning for robotic arms is a significant area of research, given its role in facilitating seamless trajectory execution and enhancing movement efficiency and accuracy. This paper focuses on the development of path planning algorithms for a robotic arm with six degrees of freedom. Specifically, three alternative approaches are explored: polynomial (cubic and quantic), Whale Optimization Algorithm (WOA), and Genetic Algorithm (GA). The comparison of outcomes between different methods revealed that polynomial methods were found to be more straightforward to implement, albeit constrained by the intricacy of the pathway. Upon examining the functioning of the WOA, it has been shown that it is well suited for all types of pathways, regardless of their level of complexity. In addition, when GA is applied, it has been shown less smoothness than WOA but also less complexity. In brief, WOA is deemed superior in the path planning process since it is more thorough in determining the optimal path due to the conical spiral path technique it employs in offering optimized path planning. in comparison to GA, WOA is better in implementation speed and accuracy. However, GA is smoother in start and finish path
Path Planning for a 6 DoF Robotic Arm Based on Whale Optimization Algorithm and Genetic Algorithm
The trajectory planning for robotic arms is a significant area of research, given its role in facilitating seamless trajectory execution and enhancing movement efficiency and accuracy. This paper focuses on the development of path planning algorithms for a robotic arm with six degrees of freedom. Specifically, three alternative approaches are explored: polynomial (cubic and quantic), Whale Optimization Algorithm (WOA), and Genetic Algorithm (GA). The comparison of outcomes between different methods revealed that polynomial methods were found to be more straightforward to implement, albeit constrained by the intricacy of the pathway. Upon examining the functioning of the WOA, it has been shown that it is well suited for all types of pathways, regardless of their level of complexity. In addition, when GA is applied, it has been shown less smoothness than WOA but also less complexity. In brief, WOA is deemed superior in the path planning process since it is more thorough in determining the optimal path due to the conical spiral path technique it employs in offering optimized path planning. in comparison to GA, WOA is better in implementation speed and accuracy. However, GA is smoother in start and finish path
- …