275 research outputs found

    The Cognitive Style (Focusing-Scanning) among Al-Quds University Students

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    This study aims to explore the cognitive style (focusing - scanning) among Al-Quds University students. A descriptive approach was used to achieve this objective. The study population included the first-term student of Al-Quds University for the academic year (2019/2020). The sample of the research consisted of (262) students who were selected using the Stratified Random Method. The validity and reliability of the study instrument were assessed. The findings showed that there were differences due to the gender in favor of females towards focusing, and to the faculty variable in favor of the faculty of Science towards focusing, the findings also revealed differences attributed to (GPA) in favor of the average (70-80). Importantly, the findings found no differences were attributed to the educational level, and that confirming the need to pay more attention to develop the cognitive styles of focusing for all university students as they affect positively the level of learning and education

    Experimental and Analytical Investigation of Hybrid Layer Thickness Effect on Replacing the Rebar for Reinforced Concrete Beams

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    Many researchers emphasize the effectiveness of steel fiber to replace the reinforcing bar in the reinforced concrete structural elements. The fiber of different types, sizes and geometries have been added to the concrete mix with a pozzolanic material to produce Ultra-High Strength Concrete (UHSC), which has excellent properties, high strength, and durability. This paper is a lab work and theoretical study consisting of casting and testing. Twenty-one simply supported RC beams to examine the beam's behavior and the shear capacity with the full or partial depth of UHSC with or without steel fibers (UHSSFRC) for replacing the reinforcing bars. The beams were divided into five groups. Preliminary experiments tests were conducted and carried out to study hardened properties of concrete such as (compressive strength, splitting tensile strength, modulus of rupture and modulus of elasticity). The selected finite element program (ANSYS) was applied to model all tested beams. It was observed that the performance of the finite element representation gives and shows good agreement with the lab work results. The test consists of failure load, deflection, cracks and failure mode. The experimental laboratory work results showed that for (1% steel fiber with reinforcement ratio ρ=0.0105 full UHSC layer) was able to give the same shear capacity for beam with (reinforcement ratio ρ=0.0157 regular concrete), while for (2% steel fiber half UHSC layer and reinforcement ratio ρ=0.0105) was able to give the same ultimate shear loads of beam with (reinforcement ratio ρ=0.0157 normal concrete). This research reveals that the hybrid layer and steel fiber effects were able to substitute for a higher reinforcement ratio with the same shear capacity.

    Correlation between Gingival Redness and Oral Health Related Quality of Life in A Group of Egyptian Children at New Giza University

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    Introduction: The concept of oral health related quality of life (OHRQoL) is of great significance in the three areas of dental health, in particular the clinical practice of dentistry, research, and education. The reported prevalence of gingivitis in various developed countries is considered high. This rate escalates with the increase in age, especially around puberty. There is evidence that gingivitis is associated with the children’s OHRQoL as there are common risk factors between gingivitis’ of adolescence and their consequent OHRQoL. Aim: This study aims to evaluate the correlation between gingival redness as evaluated by digital photographs and oral health related quality of life as measured by the short form of child perception questionnaire 11-14. Subjects and methods: 91 participants 11-14 years-old Egyptian children from New-Giza University outpatients’ clinic were recruited and OHRQoL was evaluated using the Arabic version of the regression short form (RSF) of Child perception questionnaire 11-14 (CPQ 11-14). Gingival redness was evaluated using analyzed digital photographs using Adobe Photoshop Creative Cloud (CC) 2021 software. Results: The study showed that there was insignificant (P \u3e0.05), weak (r \u3c 0.5), positive (+) correlation between the number of red pixels in digital photographs and oral symptoms domain and functional limitation domain. Conclusion: there was no statistically significant correlation between the gingival redness and the oral health related quality of life

    達成可能及び残り一つを除いて達成可能な線量体積・平均線量制約に基づく計画のための強度変調放射線治療の最適化

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    We give a novel approach for obtaining an intensity-modulated radiation therapy (IMRT) optimization solution based on the idea of continuous dynamical methods. The proposed method, which is an iterative algorithm derived from the discretization of a continuous-time dynamical system, can handle not only dose-volume but also mean-dose constraints directly in IMRT treatment planning. A theoretical proof for the convergence to an equilibrium corresponding to the desired IMRT planning is given by using the Lyapunov stability theorem. By introducing the concept of “acceptable,” which means the existence of a nonempty set of beam weights satisfying the given dose-volume and mean-dose constraints, and by using the proposed method for an acceptable IMRT planning, one can resolve the issue that the objective and evaluation are different in the conventional planning process. Moreover, in the case where the target planning is totally unacceptable and partly acceptable except for one group of dose constraints, we give a procedure that enables us to obtain a nearly optimal solution close to the desired solution for unacceptable planning. The performance of the proposed approach for an acceptable or unacceptable planning is confirmed through numerical experiments simulating a clinical setup

    Growth and Product Formation of Clostridium ljungdahlii in Presence of Cyanide

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    Cyanide is a minor constituent of crude syngas whose content depends on the feedstock and gasification procedure. It is a known poison to metal catalysts and inhibits iron-containing enzymes like carbon monoxide dehydrogenase of acetogenic organisms. Therefore, it is considered a component that has to be removed from the gas stream prior to use in chemical synthesis or syngas fermentation. We show that the growth rate and maximum biomass concentration of Clostridium ljungdahlii are unaffected by cyanide at concentrations of up to 1.0 mM with fructose as a carbon source and up to 0.1 mM with syngas as a carbon source. After the culture is adapted to cyanide it shows no growth inhibition. While the difference in growth is an increasing lag-phase with increasing cyanide concentrations, the product spectrum shifts from 97% acetic acid and 3% ethanol at 0 mM cyanide to 20% acetic acid and 80% ethanol at 1.0 mM cyanide for cultures growing on (fructose) and 80% acetic acid and 20% ethanol at 0.1 mM cyanide (syngas)

    欠損した投影の推定を伴う断層逆問題

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    Image reconstruction in computed tomography can be treated as an inverse problem, namely, obtaining pixel values of a tomographic image from measured projections. However, a seriously degraded image with artifacts is produced when a certain part of the projections is inaccurate or missing. A novel method for simultaneously obtaining a reconstructed image and an estimated projection by solving an initial-value problem of differential equations is proposed. A system of differential equations is constructed on the basis of optimizing a cost function of unknown variables for an image and a projection. Three systems described by nonlinear differential equations are constructed, and the stability of a set of equilibria corresponding to an optimized solution for each system is proved by using the Lyapunov stability theorem. To validate the theoretical result given by the proposed method, metal artifact reduction was numerically performed

    Dynamic State Estimation based Transmission Line Protection Scheme: Performance Evaluation with Different Fault Types and Conditions

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    This paper presents the experimental validation of a transmission line protection scheme based on dynamic state estimation for different fault types and conditions. The protection scheme utilizes real-time high-frequency sampled measurements from advanced sensors and evaluates the operating condition of the transmission line based on which a tripping signal is generated in case a fault occurs. The validation is performed using a physical scaled-down model of a power system, consisting of a transmission line, transformer, synchronous generator, and loads. The following faults are examined during the validation: unbalanced faults under different load conditions, high impedance fault, fault current fed from both ends, hidden failure, external fault, and load change conditions. The results show that the scheme performs as intended and thus proves its efficacy to detect various types of faults. The maximum fault detection time is calculated to be 42.5 milliseconds, while the maximum fault clearing time comes out to be 82.5 milliseconds, on par with currently employed protection methods. The obtained results demonstrate the ability of the scheme to detect different fault types under varying conditions and avoid potential issues with relay coordinatio

    Noise-Robust Image Reconstruction Based on Minimizing Extended Class of Power-Divergence Measures

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    The problem of tomographic image reconstruction can be reduced to an optimization problem of finding unknown pixel values subject to minimizing the difference between the measured and forward projections. Iterative image reconstruction algorithms provide significant improvements over transform methods in computed tomography. In this paper, we present an extended class of power-divergence measures (PDMs), which includes a large set of distance and relative entropy measures, and propose an iterative reconstruction algorithm based on the extended PDM (EPDM) as an objective function for the optimization strategy. For this purpose, we introduce a system of nonlinear differential equations whose Lyapunov function is equivalent to the EPDM. Then, we derive an iterative formula by multiplicative discretization of the continuous-time system. Since the parameterized EPDM family includes the Kullback–Leibler divergence, the resulting iterative algorithm is a natural extension of the maximum-likelihood expectation-maximization (MLEM) method. We conducted image reconstruction experiments using noisy projection data and found that the proposed algorithm outperformed MLEM and could reconstruct high-quality images that were robust to measured noise by properly selecting parameters

    Block-Iterative Reconstruction from Dynamically Selected Sparse Projection Views Using Extended Power-Divergence Measure

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    Iterative reconstruction of density pixel images from measured projections in computed tomography has attracted considerable attention. The ordered-subsets algorithm is an acceleration scheme that uses subsets of projections in a previously decided order. Several methods have been proposed to improve the convergence rate by permuting the order of the projections. However, they do not incorporate object information, such as shape, into the selection process. We propose a block-iterative reconstruction from sparse projection views with the dynamic selection of subsets based on an estimating function constructed by an extended power-divergence measure for decreasing the objective function as much as possible. We give a unified proposition for the inequality related to the difference between objective functions caused by one iteration as the theoretical basis of the proposed optimization strategy. Through the theory and numerical experiments, we show that nonuniform and sparse use of projection views leads to a reconstruction of higher-quality images and that an ordered subset is not the most effective for block-iterative reconstruction. The two-parameter class of extended power-divergence measures is the key to estimating an effective decrease in the objective function and plays a significant role in constructing a robust algorithm against noise

    Transmission Line Protection Using Dynamic State Estimation and Advanced Sensors: Experimental Validation

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    This paper presents the experimental validation of a protection scheme for a transmission line based on dynamic state estimation along with the practical application of advanced sensors in this protection scheme. The scheme performs dynamic state estimation with high-frequency measurements provided by the sensors, assesses the operating condition (i.e., health) of the transmission line in real-time, and thereby determines the tripping signal whenever a fault is detected. The validation was carried out in two steps, first with simulation studies for a three-phase fault and then with the experimental implementation using a physical scaled-down model of a power system consisting of transmission lines, transformers, and loads. The simulation and validation results have shown that the scheme performs adequately in both normal and fault conditions. In the fault case with the experimental setup, the scheme could correctly detect the fault and send the trip signal to the line’s circuit breakers with a total fault clearing time of approximately 65 milliseconds which is comparable to conventional protection methods. The average processing time for a measurement sample block is 12.5 milliseconds. The results demonstrate that this scheme and the sensors would work for transmission line protection which can avoid relay coordination and settings issues
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