612 research outputs found

    Modeling the Drying Kinetics of Green Bell Pepper in a Heat Pump Assisted Fluidized Bed Dryer

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    In this research, green bell pepper was dried in a pilot plant fluidized bed dryer equipped with a heat pump humidifier using three temperatures of 40, 50 and 60C and two airflow velocities of 2 and 3m/s in constant air moisture. Three modeling methods including nonlinear regression technique, Fuzzy Logic and Artificial Neural Networks were applied to investigate drying kinetics for the sample. Among the mathematical models, Midilli model with R=0.9998 and root mean square error (RMSE)=0.00451 showed the best fit with experimental data. Feed-Forward-Back-Propagation network with Levenberg-Marquardt training algorithm, hyperbolic tangent sigmoid transfer function, training cycle of 1,000 epoch and 2-5-1 topology, deserving R=0.99828 and mean square error (MSE)=5.5E-05, was determined as the best neural model. Overall, Neural Networks method was much more precise than two other methods in prediction of drying kinetics and control of drying parameters for green bell pepper. Practical Applications: This article deals with different modeling approaches and their effectiveness and accuracy for predicting changes in the moisture ratio of green bell pepper enduring fluidized bed drying, which is one of the most concerning issues in food factories involved in drying fruits and vegetables. This research indicates that although efficiency of mathematical modeling, Fuzzy Logic controls and Artificial Neural Networks (ANNs) were all acceptable, the modern prediction methods of Fuzzy Logic and especially ANNs were more productive and precise. Besides, this report compares our findings with previous ones carried out with the view of predicting moisture quotients of other food crops during miscellaneous drying procedures. © 2016 Wiley Periodicals, Inc

    Ch1 (Vitis vinifera L.) Rootstock Control of Scion Response to Water Stress in Some Commercial Grapevine Cultivars

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    Drought stress is the most important environmental factor limiting the growth, development and yield ofcrop plants and horticulture. In this study, the induction of drought resistance in commercial cultivars (asscion) by the Ch1 rootstock was evaluated based on physiological and biochemical responses. Factorialexperiment was performed in a completely randomised design (CRD) with three replications in thegreenhouse. Plant materials consisted of five commercial grapevine cultivars (own-rooted plants of Blackseedless, Flame seedless, Turkman seedless, Sultana and Shahani, and the scion of these cultivars graftedonto Ch1 rootstock). Drought stress treatment comprised stopping irrigation for 30 days from July to August, and not stopping irrigation was the control. Drought stress significantly reduced the membrane stability index (MSI) and the relative water content (RWC), and increased electrolyte leakage (EL), catalase, hydrogen peroxide, proline, ascorbic acid, guaiacol peroxidase, protein, sodium and potassium levels (P < 0.05). The EL and MSI in the Ch1 rootstock under drought stress decreased by 18.38% and 14.86% respectively. The Ch1 rootstock significantly increased the amount of proline, total protein and enzyme activity of guaiacol peroxidase and catalase in cultivars in a drought stress environment. The amount of hydrogen peroxide decreased in all cultivars grafted on Ch1 in both drought stress and non-drought stress environments, by 14.3% and 18.9% respectively. Sultana cultivar grafted on Ch1 rootstock showed the highest drought resistance. Therefore, it can be concluded that the Ch1 rootstock is recommended as a rootstock for inducing drought resistance in grapevine cultivar scions

    Emergence of hexatic and long-range herringbone order in two-dimensional smectic liquid crystals : A Monte Carlo study

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    Using a high resolution Monte Carlo simulation technique based on multi-histogram method and cluster-algorithm, we have investigated critical properties of a coupled XY model, consists of a six-fold symmetric hexatic and a three-fold symmetric herringbone field, in two dimensions. The simulation results demonstrate a series of novel continues transitions, in which both long-range hexatic and herringbone orderings are established simultaneously. It is found that the specific-heat anomaly exponents for some regions in coupling constants space are in excellent agreement with the experimentally measured exponents extracted from heat-capacity data near the smecticA-hexaticB transition of two-layer free standing film

    Comparing the effects of Merrill & Gagne’s instructional design models on cognitive load, learning and instructional efficiency

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    Background and Objectives: With the increasing importance of instructional multimedia and the use of their interactive and unique features in the teaching-learning process, we are witnessing the design and production of this technology and its use in teaching courses and different levels of the educational system. Cognitive load theory, as one of the theories related to information processing, is one of the most effective theories in instructional design and an effective guide for designing multimedia and other instructional materials. The basic premise of this theory is that learners have very limited working memory capacity to process when facing with new information. The purpose of this theory is to predict learning outcomes by considering the capabilities and limitations of human cognitive structure. Cognitive load theory is based on the idea that the design of instructional materials should be based on our knowledge of how the human mind works. Based on this assumption, the various processes of acquiring knowledge and understanding are explained based on the load they place on the human cognitive system (which is an active system with limited information processing capacity). Because this theory links the design features of instructional materials to the principles of human cognitive processing, it can be used in a wide range of learning environments.The present study aimed to compare the effects of Merrill and Gagne's instructional design models on students' cognitive load, learning and instructional efficiency in Science lesson. Methods: The study was quasi-experimental with pretest and posttest design with two experimental and one control groups. The statistical population consisted of all male students of the sixth grade elementary school of Qazvin. The sample including three 30 students’ classes were selected through convenience sampling procedure and the classes randomly assigned to experimental and control groups. The materials and instruments included instructional multimedia contents, learning tests, and cognitive load assessment scale. The first experimental group studied the multimedia based on the Merrill model, the second group studied the multimedia based on the Gagne model and the control group studied non-model multimedia. Data were analyzed by using analysis of covariance (ANCOVA). Findings: The results of the study showed that multimedia based on the Merrill instructional design model compared to multimedia based on Gagne instructional design model and non-model multimedia, has led to less cognitive load, more learning and instructional efficiency. Also, multimedia based on Gagne's instructional design model compared to non-model multimedia led to less cognitive load, more learning and instructional efficiency. Conclusion: One of the concerns of educational designers in the process of designing the content of multimedia educational materials and other learning materials has always been focused on the appropriate selection of instructional design models. Since there are different models for instructional design of learning materials, to choose a suitable model, one should rely on theoretical foundations and the results of research conducted in various theoretical areas, including cognitive load theory. According to the findings of this study, it is suggested that in order to reduce the cognitive load and increase students’ learning, Merrill instructional design model would be used in designing instructional multimedia content.   ===================================================================================== COPYRIGHTS  ©2020 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.  ====================================================================================

    Design and Evaluation of Magnetic Hall Effect Tactile Sensors for Use in Sensorized Splints

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    Splinting techniques are widely used in medicine to inhibit the movement of arthritic joints. Studies into the effectiveness of splinting as a method of pain reduction have generally yielded positive results, however, no significant difference has been found in clinical outcomes between splinting types. Tactile sensing has shown great promise for the integration into splinting devices and may offer further information into applied forces to find the most effective methods of splinting. Hall effect-based tactile sensors are of particular interest in this application owing to their low-cost, small size, and high robustness. One complexity of the sensors is the relationship between the elastomer geometry and the measurement range. This paper investigates the design parameters of Hall effect tactile sensors for use in hand splinting. Finite element simulations are used to locate the areas in which sensitivity is high in order to optimise the deflection range of the sensor. Further simulations then investigate the mechanical response and force ranges of the elastomer layer under loading which are validated with experimental data. A 4 mm radius, 3 mm-thick sensor is identified as meeting defined sensing requirements for range and sensitivity. A prototype sensor is produced which exhibits a pressure range of 45 kPa normal and 6 kPa shear. A proof of principle prototype demonstrates how this can be integrated to form an instrumented splint with multi-axis sensing capability and has the potential to inform clinical practice for improved splinting

    A Discrete Version of the Inverse Scattering Problem and the J-matrix Method

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    The problem of the Hamiltonian matrix in the oscillator and Laguerre basis construction from the S-matrix is treated in the context of the algebraic analogue of the Marchenko method.Comment: 11 pages. The Laguerre basis case is adde

    Reanalysis of two eclipsing binaries: EE Aqr and Z Vul

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    We study the radial-velocity and light curves of the two eclipsing binaries EE Aqr and Z Vul. Using the latest version of the Wilson & Van Hamme (2003) model, absolute parameters for the systems are determined. We find that EE Aqr and Z Vul are near-contact and semi-detached systems, respectively. The primary component of EE Aqr fills about 96% of its 'Roche lobe', while its secondary one appears close to completely filling this limiting volume. In a similar way, we find fill-out proportions of about 72 and 100% of these volumes for the primary and secondary components of Z Vul respectively. We compare our results with those of previous authors.Comment: 13 pages, 8 figures, 10 table

    Experiments on a videotape atom chip: fragmentation and transport studies

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    This paper reports on experiments with ultra-cold rubidium atoms confined in microscopic magnetic traps created using a piece of periodically-magnetized videotape mounted on an atom chip. The roughness of the confining potential is studied with atomic clouds at temperatures of a few microKelvin and at distances between 30 and 80 microns from the videotape-chip surface. The inhomogeneities in the magnetic field created by the magnetized videotape close to the central region of the chip are characterized in this way. In addition, we demonstrate a novel transport mechanism whereby we convey cold atoms confined in arrays of videotape magnetic micro-traps over distances as large as ~ 1 cm parallel to the chip surface. This conveying mechanism enables us to survey the surface of the chip and observe potential-roughness effects across different regions.Comment: 29 pages, 22 figures
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