Search results for: Kinematically admissibly velocity fieldSpatial Elementary Rigid Region (SERR)
707 A Physics-Based Model for Fast Recovery Diodes with Lifetime Control and Emitter Efficiency Reduction
Authors: Chengjie Wang, Li Yin, Chuanmin Wang
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This paper presents a physics-based model for the high-voltage fast recovery diodes. The model provides a good trade-off between reverse recovery time and forward voltage drop realized through a combination of lifetime control and emitter efficiency reduction techniques. The minority carrier lifetime can be extracted from the reverse recovery transient response and forward characteristics. This paper also shows that decreasing the amount of the excess carriers stored in the drift region will result in softer characteristics which can be achieved using a lower doping level. The developed model is verified by experiment and the measurement data agrees well with the model.Keywords: Emitter efficiency, lifetime control, P-i-N diode, physics-based model
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 3809706 Numerical Simulations of Frost Heave Using COMSOL Multiphysics Software in Unsaturated Freezing Soils
Authors: Sara Soltanpour, Adolfo Foriero
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Frost heave is arguably the most problematic adverse phenomenon in cold region areas. It is a complex process that depends on heat and water transfer. The coupled physical fields generate considerable heave stresses as well as deformations. In the present study, a coupled Thermal-Hydraulic-Mechanical (THM) model using COMSOL Multiphysics in frozen unsaturated soils, such as fine sand, is investigated. Particular attention to the frost heave and temperature distribution, as well as the water migrating during soil freezing, is assessed. The results obtained from the numerical simulations are consistent with the results measured in the full-scale tests conducted by Cold Regions Research and Engineering Laboratory (CRREL).
Keywords: Frost heave, numerical simulations, COMSOL software, unsaturated freezing soil.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 301705 Quantitative Precipitation Forecast using MM5 and WRF models for Kelantan River Basin
Authors: Wardah, T., Kamil, A.A., Sahol Hamid, A.B., Maisarah, W.W.I
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Quantitative precipitation forecast (QPF) from atmospheric model as input to hydrological model in an integrated hydro-meteorological flood forecasting system has been operational in many countries worldwide. High-resolution numerical weather prediction (NWP) models with grid cell sizes between 2 and 14 km have great potential in contributing towards reasonably accurate QPF. In this study the potential of two NWP models to forecast precipitation for a flood-prone area in a tropical region is examined. The precipitation forecasts produced from the Fifth Generation Penn State/NCAR Mesoscale (MM5) and Weather Research and Forecasting (WRF) models are statistically verified with the observed rain in Kelantan River Basin, Malaysia. The statistical verification indicates that the models have performed quite satisfactorily for low and moderate rainfall but not very satisfactory for heavy rainfall.Keywords: MM5, Numerical weather prediction (NWP), quantitative precipitation forecast (QPF), WRF
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2934704 A Comparative Study of Image Segmentation Algorithms
Authors: Mehdi Hosseinzadeh, Parisa Khoshvaght
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In some applications, such as image recognition or compression, segmentation refers to the process of partitioning a digital image into multiple segments. Image segmentation is typically used to locate objects and boundaries (lines, curves, etc.) in images. Image segmentation is to classify or cluster an image into several parts (regions) according to the feature of image, for example, the pixel value or the frequency response. More precisely, image segmentation is the process of assigning a label to every pixel in an image such that pixels with the same label share certain visual characteristics. The result of image segmentation is a set of segments that collectively cover the entire image, or a set of contours extracted from the image. Several image segmentation algorithms were proposed to segment an image before recognition or compression. Up to now, many image segmentation algorithms exist and be extensively applied in science and daily life. According to their segmentation method, we can approximately categorize them into region-based segmentation, data clustering, and edge-base segmentation. In this paper, we give a study of several popular image segmentation algorithms that are available.Keywords: Image Segmentation, hierarchical segmentation, partitional segmentation, density estimation.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2920703 Urban Transformations of the Mediterranean Cities in Light of Developments in the Modern Era
Authors: Bakr Hashem Paumey Ahmed Alashwal
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The urban transformation processes in its framework and its general significance became a fundamental and vital subject of consideration for both the developed and the developing societies. It has become important to regulate the architectural systems adopted by the city, to sustain the present development on one hand, and on the other hand, to facilitate its future growth. Thus, the study dealt with the phenomenon of urban transformation of the Mediterranean cities, and the city of Alexandria in particular, because of its significant historical and cultural legacy, its historical architecture and its contemporary urbanization. This article investigates the entirety of cities in the Mediterranean region through the analysis of the relationship between inflation and growth of these cities and the extent of the complexity of the city barriers. We hope to analyze not only the internal transformations, but the external relationships (both imperial and post-colonial) that have shaped Alexandria city growth from the nineteenth century until today.Keywords: Urban Transformations, Mediterranean cities, Modern Era, Alexandria.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2287702 Pay Differentials and Employee Retention in the State Colleges of Education in the South-South Zone, Nigeria
Authors: Emmanuel U. Ingwu
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The study examined the influence of pay differentials on employee retention in the State Colleges of Education in the South-South Region of Nigeria. 275 subjects drawn from members of the wage negotiating teams in the Colleges were administered questionnaires constructed for study. Analysis of Variance revealed that the observed pay differentials significantly influenced retainership, f(5,269 = 6.223, P< 0.05). However, the Multiple Classification Analysis and Post-Hoc test indicated that employees in two of the Colleges with slightly lower and higher pay levels may probably remain with their employers while employees in other Colleges with the least and highest pay levels suggested quitting. Based on these observations, the influence of pay on employee retention seems inconclusive. Generally, employees in the colleges studied are dissatisfied with current pay levels. Management should confront these challenges by improving pay packages to encourage employees to remain and be dedicated to duty.
Keywords: Employee, Influence, Pay differentials, Retention.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2351701 Knowledge Acquisition as Determinant of Outputs of Innovative Business in Regions of the Czech Republic
Authors: P. Hajek, J. Stejskal
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The aim of this paper is to analyze the ability to identify and acquire knowledge from external sources at the regional level in the Czech Republic. The results show that the most important sources of knowledge for innovative activities are sources within the businesses themselves, followed by customers and suppliers. Furthermore, the analysis of relationships between the objective of the innovative activity and the ability to identify and acquire knowledge implies that knowledge obtained from (1) customers aims at replacing outdated products and increasing product quality; (2) suppliers aims at increasing capacity and flexibility of production; and (3) competing businesses aims at growing market share and increasing the flexibility of production and services. Regions should therefore direct their support especially into development and strengthening of networks within the value chain.
Keywords: Knowledge, acquisition, innovative business, Czech republic, region.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1552700 Government Initiatives: The Missing Key for E-commerce Growth in KSA
Authors: R. AlGhamdi, S. Drew, S. Alkhalaf
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This paper explores the issues that influence online retailing in Saudi Arabia. Retailers in Saudi Arabia have been reserved in their adoption of electronically delivered aspects of their business. Despite the fact that Saudi Arabia has the largest and fastest growth of ICT marketplaces in the Arab region, e-commerce activities are not progressing at the same speed. Only very few Saudi companies, mostly medium and large companies from the manufacturing sector, are involved in e-commerce implementation. Based on qualitative data collected by conducting interviews with 16 retailers and 16 potential customers in Saudi Arabia, several factors influencing online retailing diffusion in Saudi Arabia are identified. However, government support comes the highest and most influencing factor for online retailing growth as identified by both parties; retailers and potential customers in Saudi Arabia.
Keywords: government support, key factor, online retailing growth, Saudi Arabia
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1853699 Quantitative Analysis of Weld Defect Images in Industrial Radiography Based Invariant Attributes
Authors: N. Nacereddine, M. Tridi, S. S. Belaïfa, M. Zelmat
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For the characterization of the weld defect region in the radiographic image, looking for features which are invariant regarding the geometrical transformations (rotation, translation and scaling) proves to be necessary because the same defect can be seen from several angles according to the orientation and the distance from the welded framework to the radiation source. Thus, panoply of geometrical attributes satisfying the above conditions is proposed and which result from the calculation of the geometrical parameters (surface, perimeter, etc.) on the one hand and the calculation of the different order moments, on the other hand. Because the large range in values of the raw features and taking into account other considerations imposed by some classifiers, the scaling of these values to lie between 0 and 1 is indispensable. The principal component analysis technique is used in order to reduce the number of the attribute variables in the aim to give better performance to the further defect classification.
Keywords: Geometric parameters, invariant attributes, principal component analysis, weld defect image.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2183698 Validation of the WAsP Model for a Terrain Surrounded by Mountainous Region
Authors: Mohammadamin Zanganeh, Vahid Khalajzadeh
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The problems associated with wind predictions of WAsP model in complex terrain are already the target of several studies in the last decade. In this paper, the influence of surrounding orography on accuracy of wind data analysis of a train is investigated. For the case study, a site with complex surrounding orography is considered. This site is located in Manjil, one of the windiest cities of Iran. For having precise evaluation of wind regime in the site, one-year wind data measurements from two metrological masts are used. To validate the obtained results from WAsP, the cross prediction between each mast is performed. The analysis reveals that WAsP model can estimate the wind speed behavior accurately. In addition, results show that this software can be used for predicting the wind regime in flat sites with complex surrounding orography.Keywords: Complex terrain, Meteorological mast, WAsPmodel, Wind prediction
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1792697 Urban Intensification and the Character of Urban Landscape: A Morphological Perspective
Authors: Xindong An, Kai Gu
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Urban intensification is regarded as the prevalent strategy in many cities of the world to ease the pressures of urban sprawl and deliver sustainable development through increasing the density of built form and activities. However, within the context of intensive development, planning and design control measures that help to maintain and promote the character of existing residential environments have been slow to develop. This causes the possible loss of the character of an area that makes a place unique and distinctive. The purpose of this paper is to explore the way of identifying the character of an urban area for the planning of urban landscape in the implementation of intensification. By employing the theory of urban morphology, the concept of morphological region is used for the analysis and characterisation of the spatial structure of the urban landscape in terms of ground plans, building types, and building and land utilisation. The morphological mapping of the character of urban landscape is suggested, which lays a foundation for more sensitive planning of urban landscape changes.
Keywords: Character areas, urban intensification, urban morphology, urban landscape.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1153696 iSEA: A Mobile Based Learning Application for History and Culture Knowledge Enhancement for the ASEAN Region
Authors: Maria Visitacion N. Gumabay, Byron Joseph A. Hallar, Annjeannette Alain D. Galang
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This study was intended to provide a more efficient and convenient way for mobile users to enhance their knowledge about ASEAN countries. The researchers evaluated the utility of the developed crossword puzzle application and assessed the general usability of its user interface for its intended purpose and audience of users. The descriptive qualitative research method for the research design and the Mobile-D methodology was employed for the development of the software application output. With a generally favorable reception from its users, the researchers concluded that the iSEA Mobile Based Learning Application can be considered ready for general deployment and use. It was also concluded that additional studies can also be done to make a more complete assessment of the knowledge gained by its users before and after using the application.
Keywords: Mobile learning, e-learning, crossword, ASEAN, iSEA.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1526695 Data Acquisition from Cell Phone using Logical Approach
Authors: Keonwoo Kim, Dowon Hong, Kyoil Chung, Jae-Cheol Ryou
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Cell phone forensics to acquire and analyze data in the cellular phone is nowadays being used in a national investigation organization and a private company. In order to collect cellular phone flash memory data, we have two methods. Firstly, it is a logical method which acquires files and directories from the file system of the cell phone flash memory. Secondly, we can get all data from bit-by-bit copy of entire physical memory using a low level access method. In this paper, we describe a forensic tool to acquire cell phone flash memory data using a logical level approach. By our tool, we can get EFS file system and peek memory data with an arbitrary region from Korea CDMA cell phone.Keywords: Forensics, logical method, acquisition, cell phone, flash memory.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 4127694 Experimental Study on Dehumidification Performance of Supersonic Nozzle
Authors: Esam Jassim
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Supersonic nozzles are commonly used to purify natural gas in gas processing technology. As an innovated technology, it is employed to overcome the deficit of the traditional method, related to gas dynamics, thermodynamics and fluid dynamics theory. An indoor test rig is built to study the dehumidification process of moisture fluid. Humid air was chosen for the study. The working fluid was circulating in an open loop, which had provision for filtering, metering, and humidifying. A stainless steel supersonic separator is constructed together with the C-D nozzle system. The result shows that dehumidification enhances as NPR increases. This is due to the high intensity in the turbulence caused by the shock formation in the divergent section. Such disturbance strengthens the centrifugal force, pushing more particles toward the near-wall region. In return return, the pressure recovery factor, defined as the ratio of the outlet static pressure of the fluid to its inlet value, decreases with NPR.
Keywords: Supersonic nozzle, dehumidification, particle separation, geometry.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1221693 Vortex Shedding on Combined Bodies at Incidence to a Uniform Air Stream
Authors: T. Yavuz, Y. E. Akansu, M. Sarıoglu, M. Ozmert
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Vortex-shedding phenomenon of the flow around combined two bodies having various geometries and sizes has been investigated experimentally in the Reynolds number range between 4.1x103 and 1.75x104. To see the effect of the rotation of the bodies on the vortex shedding, the combined bodies were rotated from 0° to 180°. The combined models have a cross section composing of a main circular cylinder and an attached circular or square cylinder. Results have shown that Strouhal numbers for two cases were changed considerably with the angle of incidence, while it was found to be largely independent of Reynolds number at 150. Characteristics of the vortex formation region and location of flow attachments, reattachments, and separations were observed by means of the flow visualizations. Depending on the inclination angle the effects of flow attachment, separation and reattachment on vortex-shedding phenomenon have been discussed.Keywords: Bluff body, vortex shedding, flow separation, flow reattachment
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2126692 Historical Landscape Affects Present Tree Density in Paddy Field
Authors: Ha T. Pham, Shuichi Miyagawa
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Ongoing landscape transformation is one of the major causes behind disappearance of traditional landscapes, and lead to species and resource loss. Tree in paddy fields in the northeast of Thailand is one of those traditional landscapes. Using three different historical time layers, we acknowledged the severe deforestation and rapid urbanization happened in the region. Despite the general thinking of decline in tree density as consequences, the heterogeneous trend of changes in total tree density in three studied landscapes denied the hypothesis that number of trees in paddy field depend on the length of land use practice. On the other hand, due to selection of planting new trees on levees, existence of trees in paddy field now relies on their values for human use. Besides, changes in land use and landscape structure had a significant impact on decision of which tree density level is considered as suitable for the landscape.
Keywords: Aerial photographs, land use change, traditional landscape, tree in paddy fields.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1867691 Feasibility Study and Developing Appropriate Hybrid Energy Systems in Regional Level
Authors: Ahmad Rouhani
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Iran has several potential for using renewable energies, so use them could significantly contribute to energy supply. The purpose of this paper is to identify the potential of the country and select the appropriate DG technologies with consideration the potential and primary energy resources in the regions. In this context, hybrid energy systems proportionate with the potential of different regions will be determined based on technical, economic, and environmental aspect. In the following the proposed structure will be optimized in terms of size and cost. DG technologies used in this project include photovoltaic system, wind turbine, diesel generator and battery bank. The HOMER software is applied for choosing the appropriate structure and the optimization of system sizing. The results have been analyzed in terms of technical and economic. The performance and the cost of each project demonstrate the appropriate structure of hybrid energy system in that region.
Keywords: Feasibility, Hybrid Energy System, Iran, Renewable Energy.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2603690 Theoretical and Analytical Approaches for Investigating the Relations between Sediment Transport and Channel Shape
Authors: Nidal Hadadin
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This study investigated the effect of cross sectional geometry on sediment transport rate. The processes of sediment transport are generally associated to environmental management, such as pollution caused by the forming of suspended sediment in the channel network of a watershed and preserving physical habitats and native vegetations, and engineering applications, such as the influence of sediment transport on hydraulic structures and flood control design. Many equations have been proposed for computing the sediment transport, the influence of many variables on sediment transport has been understood; however, the effect of other variables still requires further research. For open channel flow, sediment transport capacity is recognized to be a function of friction slope, flow velocity, grain size, grain roughness and form roughness, the hydraulic radius of the bed section and the type and quantity of vegetation cover. The effect of cross sectional geometry of the channel on sediment transport is one of the variables that need additional investigation. The width-depth ratio (W/d) is a comparative indicator of the channel shape. The width is the total distance across the channel and the depth is the mean depth of the channel. The mean depth is best calculated as total cross-sectional area divided by the top width. Channels with high W/d ratios tend to be shallow and wide, while channels with low (W/d) ratios tend to be narrow and deep. In this study, the effects of the width-depth ratio on sediment transport was demonstrated theoretically by inserting the shape factor in sediment continuity equation and analytically by utilizing the field data sets for Yalobusha River. It was found by utilizing the two approaches as a width-depth ratio increases the sediment transport decreases.Keywords: Sediment transport, shape factor, hydraulicgeometry, flow discharge, width depth ratio.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1397689 Optimal Estimation of Surface Reflectance from Landsat TM Visible and Mid Infrared Data over Penang Island
Authors: H. S. Lim, M. Z. MatJafri, K. Abdullah, N. Mohd. Saleh
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Retrieval of the surface reflectance is important in the remotely sensed data analysis to obtain the atmospheric reflectance or atmospheric correction. The relationship between visible and mid infrared reflectance over land was investigated and developed in this study. The surface reflectances of the two visible bands were measured using a handheld spectroradiometer collected around Penang Island. In this study, we use the assumption that the 2.1 μm band is not affected by aerosol and it is transparent to most aerosol types (except dust). Therefore the satellite observed signal is the same as the surface signal in 2.1 μm band. The correlation between the surface reflectance measured by the spectroradiometer in the blue and red region and the 2.1 μm observed by the satellite has been established. We investigate five dates of Landsat TM scenes in this study. The finding obtained by this study indicates that the surface reflectance can be retrieved from the 2.1 μm band.Keywords: Surface Reflectance, Landsat TM, Aerosol, Spectroradiometer.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1202688 Somatic Embryogenesis for Agropyron cristatum on Murashige and Skoog Medium
Authors: Masoume Amirkhani, Kambiz Mashayekhi, Maurizio Lambardi
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Agropyron cristatum L. Gaertn. is a native grass of semiarid region in Iran which is quit resistant to cool and drought climate and withstand heavy grazing. This species has close phylogenetic relationship with Triticum and Hordeum. In this research, the effect of seven different concentrations of growth regulator 2,4-D on callus production and somatic embryogenesis of A. cristatum was investigated on Murashige and Skoog medium. The results showed that the rate of callus, embryo and neomorph were highest in 1 mg L-1 2,4-D. Callus production was increased in 1 mg L-1 2,4-D but dramatically decreased at 5.5 and 9 mg L-1 2,4-D. The somatic embryos were observed at 1 and 4 mg L-1 2,4-D but matured embryos and plantlet were only occurred at 1 mg L-1 2,4-D. There were significant differences between 1 mg L-1 2,4-D and other treatments for producing globular and torpedo embryos, plantlet, rooted callus and number of roots (p<0.05) and there was not any callus production and embryogenesis in control treatment without growth regulator.Keywords: 2, 4-D, callus production, somatic embryogenesis, Agropyron cristatum.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1584687 Influence of Environment-Friendly Organic Wastes on the Properties of Sandy Soil under Growing Zea mays L. in Arid Regions
Authors: Mohamed Rashad, Mohamed Hafez, Mohamed Emran, Emad Aboukila, Ibrahim Nassar
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Environment-friendly organic wastes of Brewers' spent grain, a byproduct of the brewing process, have recently used as soil amendment to improve soil fertility and plant production. In this work, treatments of 1% (T1) and 2% (T2) of spent grains, 1% (C1) and 2% (C2) of compost and mix of both sources (C1T1) were used and compared to the control for growing Zea mays L. on sandy soil under arid Mediterranean climate. Soils were previously incubated at 65% saturation capacity for a month. The most relevant soil physical and chemical parameters were analysed. Water holding capacity and soil organic matter (OM) increased significantly along the treatments with the highest values in T2. Soil pH decreased along the treatments and the lowest pH was in C1T1. Bicarbonate decreased by 69% in C1T1 comparing to control. Total nitrogen (TN) and available P varied significantly among all treatments and T2, C1T1 and C2 treatments increased 25, 17 and 11 folds in TN and 1.2, 0.6 and 0.3 folds in P, respectively related to control. Available K showed the highest values in C1T1. Soil micronutrients increased significantly along all treatments with the highest values in T2. After corn germination, significant variation was observed in the velocity of germination coefficients (VGC) among all treatments in the order of C1T1>T2>T1>C2>C1>control. The highest records of final germination and germination index were in C1T1 and T2. The spent grains may compensate deficiencies of macro and micronutrients in newly reclaimed sandy soils without adverse effects to sustain crop production with a rider that excessive or continuous use need to be circumvented.Keywords: Spent grain, compost, micronutrients, macronutrients, water holding capacity, plant growth.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1141686 Mechanical Behavior of Recycled Pet Fiber Reinforced Concrete Matrix
Authors: Comingstarful Marthong, Deba Kumar Sarma
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Concrete is strong in compression however weak in tension. The tensile strength as well as ductile property of concrete could be improved by addition of short dispersed fibers. Polyethylene terephthalate (PET) fiber obtained from hand cutting or mechanical slitting of plastic sheets generally used as discrete reinforcement in substitution of steel fiber. PET fiber obtained from the former process is in the form of straight slit sheet pattern that impart weaker mechanical bonding behavior in the concrete matrix. To improve the limitation of straight slit sheet fiber the present study considered two additional geometry of fiber namely (a) flattened end slit sheet and (b) deformed slit sheet. The mix for plain concrete was design for a compressive strength of 25 MPa at 28 days curing time with a watercement ratio of 0.5. Cylindrical and beam specimens with 0.5% fibers volume fraction and without fibers were cast to investigate the influence of geometry on the mechanical properties of concrete. The performance parameters mainly studied include flexural strength, splitting tensile strength, compressive strength and ultrasonic pulse velocity (UPV). Test results show that geometry of fiber has a marginal effect on the workability of concrete. However, it plays a significant role in achieving a good compressive and tensile strength of concrete. Further, significant improvement in term of flexural and energy dissipation capacity were observed from other fibers as compared to the straight slit sheet pattern. Also, the inclusion of PET fiber improved the ability in absorbing energy in the post-cracking state of the specimen as well as no significant porous structures.Keywords: Concrete matrix, polyethylene terephthalate (PET) fibers, mechanical bonding, mechanical properties, UPV.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2057685 CFD Study of Subcooled Boiling Flow at Elevated Pressure Using a Mechanistic Wall Heat Partitioning Model
Authors: Machimontorn Promtong, Sherman C. P. Cheung, Guan H. Yeoh, Sara Vahaji, Jiyuan Tu
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The wide range of industrial applications involved with boiling flows promotes the necessity of establishing fundamental knowledge in boiling flow phenomena. For this purpose, a number of experimental and numerical researches have been performed to elucidate the underlying physics of this flow. In this paper, the improved wall boiling models, implemented on ANSYS CFX 14.5, were introduced to study subcooled boiling flow at elevated pressure. At the heated wall boundary, the Fractal model, Force balance approach and Mechanistic frequency model are given for predicting the nucleation site density, bubble departure diameter, and bubble departure frequency. The presented wall heat flux partitioning closures were modified to consider the influence of bubble sliding along the wall before the lift-off, which usually happens in the flow boiling. The simulation was performed based on the Two-fluid model, where the standard k-ω SST model was selected for turbulence modelling. Existing experimental data at around 5 bars were chosen to evaluate the accuracy of the presented mechanistic approach. The void fraction and Interfacial Area Concentration (IAC) are in good agreement with the experimental data. However, the predicted bubble velocity and Sauter Mean Diameter (SMD) are over-predicted. This over-prediction may be caused by consideration of only dispersed and spherical bubbles in the simulations. In the future work, the important physical mechanisms of bubbles, such as merging and shrinking during sliding on the heated wall will be incorporated into this mechanistic model to enhance its capability for a wider range of flow prediction.
Keywords: CFD, mechanistic model, subcooled boiling flow, two-fluid model.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1273684 Photograph Based Pair-matching Recognition of Human Faces
Authors: Min Yao, Kota Aoki, Hiroshi Nagahashi
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In this paper, a novel system recognition of human faces without using face different color photographs is proposed. It mainly in face detection, normalization and recognition. Foot method of combination of Haar-like face determined segmentation and region-based histogram stretchi (RHST) is proposed to achieve more accurate perf using Haar. Apart from an effective angle norm side-face (pose) normalization, which is almost a might be important and beneficial for the prepr introduced. Then histogram-based and photom normalization methods are investigated and ada retinex (ASR) is selected for its satisfactory illumin Finally, weighted multi-block local binary pattern with 3 distance measures is applied for pair-mat Experimental results show its advantageous perfo with PCA and multi-block LBP, based on a principle.Keywords: Face detection, pair-matching rec normalization, skin color segmentation.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1601683 Numerical Analysis of Laminar Reflux Condensation from Gas-Vapour Mixtures in Vertical Parallel Plate Channels
Authors: Foad Hassaninejadafarahani, Scott Ormiston
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Reflux condensation occurs in vertical channels and tubes when there is an upward core flow of vapour (or gas-vapour mixture) and a downward flow of the liquid film. The understanding of this condensation configuration is crucial in the design of reflux condensers, distillation columns, and in loss-of-coolant safety analyses in nuclear power plant steam generators. The unique feature of this flow is the upward flow of the vapour-gas mixture (or pure vapour) that retards the liquid flow via shear at the liquid-mixture interface. The present model solves the full, elliptic governing equations in both the film and the gas-vapour core flow. The computational mesh is non-orthogonal and adapts dynamically the phase interface, thus produces a sharp and accurate interface. Shear forces and heat and mass transfer at the interface are accounted for fundamentally. This modeling is a big step ahead of current capabilities by removing the limitations of previous reflux condensation models which inherently cannot account for the detailed local balances of shear, mass, and heat transfer at the interface. Discretisation has been done based on finite volume method and co-located variable storage scheme. An in-house computer code was developed to implement the numerical solution scheme. Detailed results are presented for laminar reflux condensation from steam-air mixtures flowing in vertical parallel plate channels. The results include velocity and gas mass fraction profiles, as well as axial variations of film thickness.
Keywords: Reflux Condensation, Heat Transfer, Channel, Laminar Flow
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1854682 Differentiation between Common Tick Species Using Molecular Biology Techniques in Saudi Arabia
Authors: Kholoud A. Al-Shammery , Badr El-Sabah A. Fetoh, Ahmed M. Alshammari
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Protein and Esterase electrophoresis were used to genetically identify two Saudi tick species. Engorged females of the camel tick Hyalomma dromedarii (Koch) (Acari: Ixodidae) and the cattle tick Boophilus annulatus (Say) (Acari: Ixodidae) ticks collected from infested camels and cattle in the animals resting house at Hail region in KSA were used. The results showed that there are a variation in both of protein and esterase activity levels and a high polymorphism within and between the genera and species of Hyalomma and Boophilus . In conclusion, the protein and esterase electrophoretic analysis used in the present study could successfully distinguish among tick species, commonly found in Saudi Arabia.Keywords: Molecular biology, The camel tick Hyalomma dromedarii, The cattle tick Boophilus annulatus , Ticks.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2947681 Embodied Energy in Concrete and Structural Masonry on Typical Brazilian Buildings
Authors: Marco A. S. González, Marlova P. Kulakowski, Luciano G. Breitenbach, Felipe Kirch
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The AEC sector has an expressive environmental responsibility. Actually, most building materials have severe environmental impacts along their production cycle. Professionals enrolled in building design may choice the materials and techniques with less impact among the viable options. This work presents a study about embodied energy in materials of two typical Brazilian constructive alternatives. The construction options considered are reinforced concrete structure and structural masonry. The study was developed for the region of São Leopoldo, southern Brazil. Results indicated that the energy embodied in these two constructive systems is approximately 1.72 GJ·m-2 and 1.26 GJ·m-2, respectively. It may be concluded that the embodied energy is lower in the structural masonry system, with a reduction around to 1/4 in relation to the traditional option. The results can be used to help design decisions.
Keywords: Civil construction, sustainability, embodied energy.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2756680 Use of Multiple Linear Regressions to Evaluate the Influence of O3 and PM10 on Biological Pollutants
Authors: S. I. V. Sousa, F.G. Martins, M. C. Pereira, M. C. M. Alvim-Ferraz, H. Ribeiro, M. Oliveira, I. Abreu
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Exposure to ambient air pollution has been linked to a number of health outcomes, starting from modest transient changes in the respiratory tract and impaired pulmonary function, continuing to restrict activity/reduce performance and to the increase emergency rooms visits, hospital admissions or mortality. The increase of allergenic symptoms has been associated with air contaminants such as ozone, particulate matter, fungal spores and pollen. Considering the potential relevance of crossed effects of nonbiological pollutants and airborne pollens and fungal spores on allergy worsening, the aim of this work was to evaluate the influence of non-biological pollutants (O3 and PM10) and meteorological parameters on the concentrations of pollen and fungal spores using multiple linear regressions. The data considered in this study were collected in Oporto which is the second largest Portuguese city, located in the North. Daily mean of O3, PM10, pollen and fungal spore concentrations, temperature, relative humidity, precipitation, wind velocity, pollen and fungal spore concentrations, for 2003, 2004 and 2005 were considered. Results showed that the 90th percentile of the adjusted coefficient of determination, P90 (R2aj), of the multiple regressions varied from 0.613 to 0.916 for pollen and from 0.275 to 0.512 for fungal spores. O3 and PM10 showed to have some influence on the biological pollutants. Among the meteorological parameters analysed, temperature was the one that most influenced the pollen and fungal spores airborne concentrations. Relative humidity also showed to have some influence on the fungal spore dispersion. Nevertheless, the models for each pollen and fungal spore were different depending on the analysed period, which means that the correlations identified as statistically significant can not be, even so, consistent enough.Keywords: Air pollutants, meteorological parameters, biologicalpollutants, multiple linear correlations.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1597679 MiRNAs as Regulators of Tumour Suppressor Expression
Authors: Olga A. Berillo, Gaukhar K. Baidildinova, Аnatoliy Т. Ivashchenko
Abstract:
Tumour suppressors are key participants in the prevention of cancer. Regulation of their expression through miRNAs is important for comprehensive translation inhibition of tumour suppressors and elucidation of carcinogenesis mechanisms. We studies the possibility of 1521 miRNAs to bind with 873 mRNAs of human tumour suppressors using RNAHybrid 2.1 and ERNAhybrid programmes. Only 978 miRNAs were found to be translational regulators of 812 mRNAs, and 61 mRNAs did not have any miRNA binding sites. Additionally, 45.9% of all miRNA binding sites were located in coding sequences (CDSs), 33.8% were located in 3' untranslated region (UTR), and 20.3% were located in the 5'UTR. MiRNAs binding with more than 50 target mRNAs and mRNAs binding with several miRNAs were selected. Hsa-miR-5096 had 15 perfectly complementary binding sites with mRNAs of 14 tumour suppressors. These newly indentified miRNA binding sites can be used in the development of medicines (anti-sense therapies) for cancer treatment.Keywords: Exonic miRNA, intergenic miRNA, intronic miRNA, tumor suppressor.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1837678 Speech Enhancement of Vowels Based on Pitch and Formant Frequency
Authors: R. Rishma Rodrigo, R. Radhika, M. Vanitha Lakshmi
Abstract:
Numerous signal processing based speech enhancement systems have been proposed to improve intelligibility in the presence of noise. Traditionally, studies of neural vowel encoding have focused on the representation of formants (peaks in vowel spectra) in the discharge patterns of the population of auditory-nerve (AN) fibers. A method is presented for recording high-frequency speech components into a low-frequency region, to increase audibility for hearing loss listeners. The purpose of the paper is to enhance the formant of the speech based on the Kaiser window. The pitch and formant of the signal is based on the auto correlation, zero crossing and magnitude difference function. The formant enhancement stage aims to restore the representation of formants at the level of the midbrain. A MATLAB software’s are used for the implementation of the system with low complexity is developed.
Keywords: Formant estimation, formant enhancement, pitch detection, speech analysis.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1643