Search results for: high viscous fluid

Authors: Anahita Suri

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Myriad cultures form the warp and weft of the fabric of this world. The last century saw mass migration of people across geographical boundaries, owing to industrialization and globalization. These people took with them their cultures, costumes, traditions, and folklore, which mingled with the local cultures to create something new and place it in a different context to make it contemporary. With the surge in population and growth of the fashion industry, there has been an increasing demand for innovative and individual fashion, from street markets to luxury brands. Exhausted by local influences, designers take inspiration from the so called ‘low’ culture and create artistic products, place it in a different context, and the end-product is categorized as ‘high’ culture. It is challenging as to why a design/culture is ‘high’ or ‘low’. Who decides which works, practices, activities, etc., are ‘high’ and which are ‘low’? The justification for this distinction is often found not in the design itself but the context attached to it. Also, the concept of high/ low is relative to time- what is ‘high’ today can be ‘low’ tomorrow and ‘high’ again the day after. This raises certain concerns. Firstly, it is sad that a culture which offers inspiration is looked down upon as ‘low’ culture. Secondly, it is ironic because the so designated ‘high’ culture is a manipulation of the truth from the authentic ‘low’ culture, which is capable of true expression. When you borrow from a different culture, you pretend to be authentic because you actually are not. Finally, it is important to be aware of crossing cultural boundaries and the context attached to a design/product so as to use it a responsible way that communicates the design without offending anyone. Is it ok for a person’s cultural identity to become another person’s fashion accessory? This essay explores the complex, multi-layered subject of fashion appropriation and aims to provoke debate over cultural ‘borrowing’ and create awareness that commodification of cultural symbols and iconography in fashion is inappropriate and offensive and not the same as ‘celebrating cultural differences’.

Keywords: context, culture, fashion appropriation, inoffensive, responsible

Procedia PDF Downloads 121

Authors: Mahdi Hamzehei, Seyyed Amin Hakim, Nahid Taherian

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Fins play an important role in increasing the efficiency of compact shell and tube heat exchangers by increasing heat transfer. The objective of this paper is to determine the optimum fin wave angle, as one of the geometric parameters affecting the efficiency of the heat exchangers. To this end, finite volume method is used to model and simulate the flow in heat exchanger. In this study, computational fluid dynamics simulations of wave channel are done. The results show that the wave angle affects the temperature output of the heat exchanger.

Keywords: fin wave angle, tube, intercooler, optimum, performance

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Authors: Mahmoud H. Abu Elella, Riham R. Mohamed, Magdy W. Sabaa

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Firstly, synthesis of N-Quaternized Chitosan (NQC), then it was proven by FTIR and 1H-NMR analysis. The degree of quaternization(DQ 35% ) was determined by equation. Secondly, synthesis of cross-linked hydrogels composed of NQC and poly (vinyl alcohol) (PVA) in different weight ratios in presence of glutaraldehyde (GA) as cross-linking agent. Characterization of the prepared hydrogels was done using FTIR, SEM, XRD,and TGA. Swellability in simulated body fluid (SBF) solutions applied on NQC / PVA hydrogels and swelling rate(Wt%) and metal ions uptake was done on it.

Keywords: hydrogel, metal ions uptake, N-quaternized chitosan, poly (vinyl alcohol), swellability

Procedia PDF Downloads 426

Authors: Tommy Lo

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This paper presented the changes in temperature and air ventilation of an inner urban area at different development stages during 2002 to 2012 and the high-rise buildings to be built in 2018. 3D simulation models ENVI-met and Autodesk Falcon were used. The results indicated that replacement of old residence buildings or open space with high-rise buildings will increase the air temperature of inner urban area; the air temperature at the pedestrian level will increase more than that at the upper levels. The temperature of the inner street in future will get higher than that in 2002, 2008 and 2012. It is attributed that heat is trapped in the street canyons as the air permeability at the pedestrian levels is lower. High-rise buildings with massive podium will further reduce the air ventilation in that area. In addition, sufficient separations among buildings is essential in design. High-rise buildings aligned along the waterfront will obstruct the wind flowing into the inner urban area and accelerate the temperature increase both in daytime and night time.

Keywords: micro-climate change, urban design, ENVI-met, construction engineering

Procedia PDF Downloads 279

Authors: Han Longxiang

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In the process of treating industrial oil wastewater with complex components, the traditional treatment methods (flotation, coagulation, microwave heating, etc.) often produce high operating costs, secondary pollution, and other problems. In order to solve these problems, the materials with high flux and stability applied to surfactant-stabilized emulsions separation have gained huge attention in the treatment of oily wastewater. Nevertheless, four stable oil-in-water emulsions can be formed due to different surfactants (surfactant-free, anionic surfactant, cationic surfactant, and non-ionic surfactant), and the previous advanced materials can only separate one or several of them, cannot effectively separate in one step. Herein, a facile synthesis method of graphene-based multilevel filter materials (GMFM) can efficiently separate the oil-in-water emulsions stabilized with different surfactants only through its gravity. The prepared materials with high stability of 20 cycles show a high flux of ~ 5000 L m-2 h-1 with a high separation efficiency of > 99.9 %. GMFM can effectively separate the emulsion stabilized by mixed surfactants and oily wastewater from factories. The results indicate that the GMFM has a wide range of applications in oil-in-water emulsions separation in industry and environmental science.

Keywords: emulsion, filtration, graphene, one-step

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Authors: C. Chhorn, S. H. Han, S. W. Lee

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Roller-compacted concrete (RCC) has been used for decades in many pavement applications due to its economic cost and high construction speed. However, due to the lack of deep researches and experiences, this material has not been widely employed. An RCC mixture with appropriate consistency can induce high compacted density, while high density can induce good aggregate interlock and high strength. Consistency of RCC is mainly known to define its constructability. However, it was not well specified how this property may affect other properties of a constructed RCC pavement (RCCP). This study suggested the possibility of an ideal range of consistency that may provide adequate quality of RCCP. In this research, five sections of RCCP consisted of both 13 mm and 19 mm aggregate sections were investigated. The effects of consistency on compacted depth, strength, international roughness index (IRI), skid resistance are examined. From this study, a new range of consistency is suggested for RCCP application.

Keywords: compacted depth, consistency, international roughness index (IRI), pavement, roller-compacted concrete (RCC), skid resistance, strength

Procedia PDF Downloads 238

Authors: Maddumage Don Sandeepa Lakshad Wimalananda, Jae-Kwan Kim, Ji-Myon Lee

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Graphene is an extraordinary 2D material that shows superior electrical, optical, and mechanical properties for the applications such as transparent contacts. Further, chemical vapor deposition (CVD) technique facilitates to synthesizing of large-area graphene, including transferability. The abstract is describing the use of high surface free energy (SFE) and nano-scale high-density surface kinks (rough) existing Cu foil for CVD graphene growth, which is an opposite approach to modern use of catalytic surfaces for high-quality graphene growth, but the controllable rough morphological nature opens new era to fast synthesis (less than the 50s with a short annealing process) of graphene as a continuous film over conventional longer process (30 min growth). The experiments were shown that high SFE condition and surface kinks on Cu(100) crystal plane existing Cu catalytic surface facilitated to synthesize graphene with high monolayer and continuous nature because it can influence the adsorption of C species with high concentration and which can be facilitated by faster nucleation and growth of graphene. The fast nucleation and growth are lowering the diffusion of C atoms to Cu-graphene interface, which is resulting in no or negligible formation of bilayer patches. High energy (500W) Ar plasma treatment (inductively Coupled plasma) was facilitated to form rough and high SFE existing (54.92 mJm-2) Cu foil. This surface was used to grow the graphene by using CVD technique at 1000C for 50s. The introduced kink-like high SFE existing point on Cu(100) crystal plane facilitated to faster nucleation of graphene with a high monolayer ratio (I2D/IG is 2.42) compared to another different kind of smooth morphological and low SFE existing Cu surfaces such as Smoother surface, which is prepared by the redeposit of Cu evaporating atoms during the annealing (RRMS is 13.3nm). Even high SFE condition was favorable to synthesize graphene with monolayer and continuous nature; It fails to maintain clean (surface contains amorphous C clusters) and defect-free condition (ID/IG is 0.46) because of high SFE of Cu foil at the graphene growth stage. A post annealing process was used to heal and overcome previously mentioned problems. Different CVD atmospheres such as CH4 and H2 were used, and it was observed that there is a negligible change in graphene nature (number of layers and continuous condition) but it was observed that there is a significant difference in graphene quality because the ID/IG ratio of the graphene was reduced to 0.21 after the post-annealing with H2 gas. Addition to the change of graphene defectiveness the FE-SEM images show there was a reduction of C cluster contamination of the surface. High SFE conditions are favorable to form graphene as a monolayer and continuous film, but it fails to provide defect-free graphene. Further, plasma modified high SFE existing surface can be used to synthesize graphene within 50s, and a post annealing process can be used to reduce the defectiveness.

Keywords: chemical vapor deposition, graphene, morphology, plasma, surface free energy

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Authors: João F. A. Martos, Felipe J. Costa, Sergio N. P. Laiton, Bruno C. Lima, Israel S. Rêgo, Paulo P. G. Toro

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Nowadays, the scramjet is a topic that has attracted the attention of several scientific communities (USA, Australia, Germany, France, Japan, India, China, Russia), that are investing in this in this type of propulsion system due its interest to facilitate access to space and reach hypersonic speed, who have invested in this type of propulsion due to the interest in facilitating access to space. The Brazilian hypersonic scramjet aerospace vehicle 14-X B is a technological demonstrator of a hypersonic airbreathing propulsion system based on the supersonic combustion (scramjet) intended to be tested in flight into the Earth's atmosphere at 30 km altitude and Mach number 7. The 14-X B has been designed at the Prof. Henry T. Nagamatsu Laboratory of Aerothermodynamics and Hypersonics of the Institute for Advanced Studies (IEAv) in Brazil. The IEAv Hypersonic Shock Tunnel, named T3, is a ground-test facility able to reproduce the flight conditions as the Mach number as well as pressure and temperature in the test section close to those encountered during the test flight of the vehicle 14-X B into design conditions. A 1-m long stainless steel 14-X B model was experimentally investigated at T3 Hypersonic Shock Tunnel, for freestream Mach number 7. Static pressure measurements along the lower surface of the 14-X B model, along with high-speed schlieren photographs taken from the 5.5° leading edge and the 14.5° deflection compression ramp, provided experimental data that were compared to the analytical-theoretical solutions and the computational fluid dynamics (CFD) simulations. The results show a good qualitative agreement, and in consequence demonstrating the importance of these methods in the project of the 14-X B hypersonic aerospace vehicle.

Keywords: 14-X, CFD, hypersonic, hypersonic shock tunnel, scramjet

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Authors: Subodh Kumar, Amit Varde

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Typical on-premises high-performance computing (HPC) environments consist of a fixed number and a fixed set of computing hardware. During the design of the HPC environment, the hardware components, including but not limited to CPU, Memory, GPU, and networking, are carefully chosen from select vendors for optimal performance. High capital cost for building the environment is a prime factor influencing the design environment. A class of software called “Job Schedulers” are critical to maximizing these resources and running multiple workloads to extract the maximum value for the high capital cost. In principle, schedulers work by preventing workloads and users from monopolizing the finite hardware resources by queuing jobs in a workload. A cloud-based HPC environment does not have the limitations of fixed (type of and quantity of) hardware resources. In theory, users and workloads could spin up any number and type of hardware resource. This paper discusses the limitations of using traditional scheduling algorithms for cloud-based HPC workloads. It proposes a new set of features, called “HPC optimizers,” for maximizing the benefits of the elasticity and scalability of the cloud with the goal of cost-performance optimization of the workload.

Keywords: high performance computing, HPC, cloud computing, optimization, schedulers

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Authors: Yoko Suganuma Oi

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The purpose of the present study is to find the efficacy of high school student self-assessment of written production. It aimed to explore the following two research questions: 1)How is topic development of their written production improved after student self-assessment and teacher feedback? 2)Does the consistency between student self-assessment and teacher assessment develop after student self-assessment and teacher feedback? The data came from the written production of 82 Japanese high school students aged from 16 to 18 years old, an American English teacher and one Japanese English teacher. Students were asked to write English compositions, about 150 words, for thirty minutes without using dictionaries. It was conducted twice at intervals of two months. Students were supposed to assess their own compositions by themselves. Teachers also assessed students’ compositions using the same assessment sheet. The results showed that both teachers and students assessed the second compositions higher than the first compositions. However, there was not the development of the consistency in coherence.

Keywords: feedback, self-assessment, topic development, high school students

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Authors: F. Esfandyari Darabad, Z. Samadi

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Natural environments have always been affected by one of the most important natural hazards, which is called, the mass movements that cause instability. Identifying the unstable regions and separating them so as to detect and determine the risk of environmental factors is one of the important issues in mountainous areas development. In this study, the northwest of Sabalan hillsides overlooking the Meshkin city and the surrounding area of that have been delimitated, in order to analyze the range processes such as landslides and debris flows based on structural and geomorphological conditions, by means of using GIS. This area due to the high slope of the hillsides and height of the region and the poor localization of roads and so because of them destabilizing the ranges own an inappropriate situation. This study is done with the purpose of identifying the effective factors in the range motion and determining the areas with high potential for zoning these movements by using GIS. The results showed that the most common range movements in the area, are debris flows, rocks falling and landslides. The effective factors in each one of the mass movements, considering a small amount of weight for each factor, the weight map of each factor and finally, the map of risk zoning for the range movements were provided. Based on the zoning map resulted in the study area, the risking level of damaging has specified into the four zones of very high risk, high risk, medium risk, low risk, in which areas with very high and high risk are settled near the road and along the Khyav river and in the  mountainous district.

Keywords: debris flow, environmental hazards, GIS, landslide

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Authors: Artur Tyliszczak, Ewa Szymanek, Maciej Marek

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Flow through granular materials is important to a vast array of industries, for instance in construction industry where granular layers are used for bulkheads and isolators, in chemical engineering and catalytic reactors where large surfaces of packed granular beds intensify chemical reactions, or in energy production systems, where granulates are promising materials for heat storage and heat transfer media. Despite the common usage of granulates and extensive research performed in this field, phenomena occurring between granular solid elements or between solids and fluid are still not fully understood. In the present work we analyze the heat exchange process between the flowing medium (gas, liquid) and solid material inside the granular layers. We consider them as a composite of isolated solid elements and inter-granular spaces in which a gas or liquid can flow. The structure of the layer is controlled by shapes of particular granular elements (e.g., spheres, cylinders, cubes, Raschig rings), its spatial distribution or effective characteristic dimension (total volume or surface area). We will analyze to what extent alteration of these parameters influences on flow characteristics (turbulent intensity, mixing efficiency, heat transfer) inside the layer and behind it. Analysis of flow inside granular layers is very complicated because the use of classical experimental techniques (LDA, PIV, fibber probes) inside the layers is practically impossible, whereas the use of probes (e.g. thermocouples, Pitot tubes) requires drilling of holes inside the solid material. Hence, measurements of the flow inside granular layers are usually performed using for instance advanced X-ray tomography. In this respect, theoretical or numerical analyses of flow inside granulates seem crucial. Application of discrete element methods in combination with the classical finite volume/finite difference approaches is problematic as a mesh generation process for complex granular material can be very arduous. A good alternative for simulation of flow in complex domains is an immersed boundary-volume penalization (IB-VP) in which the computational meshes have simple Cartesian structure and impact of solid objects on the fluid is mimicked by source terms added to the Navier-Stokes and energy equations. The present paper focuses on application of the IB-VP method combined with large eddy simulation (LES). The flow solver used in this work is a high-order code (SAILOR), which was used previously in various studies, including laminar/turbulent transition in free flows and also for flows in wavy channels, wavy pipes and over various shape obstacles. In these cases a formal order of approximation turned out to be in between 1 and 2, depending on the test case. The current research concentrates on analyses of the flows in dense granular layers with elements distributed in a deterministic regular manner and validation of the results obtained using LES-IB method and body-fitted approach. The comparisons are very promising and show very good agreement. It is found that the size, number of elements and their distribution have huge impact on the obtained results. Ordering of the granular elements (or lack of it) affects both the pressure drop and efficiency of the heat transfer as it significantly changes mixing process.

Keywords: granular layers, heat transfer, immersed boundary method, numerical simulations

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Authors: T. B. Karu Jayasundara

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The Earth’s gravity is not uniform. The satellite imageries of the Earth’s surface from NASA reveal a number of different gravity anomaly regions all over the globe. When the moon rotates around the earth, its gravity has a major physical influence on a number of regions on the earth. This physical change can be seen by the tides. The tides make sea levels high and low in coastal regions. During high tide, the gravitational force of the Moon pulls the Earth’s gravity so that the total gravitational intensity of Earth is reduced; it is further reduced in the low gravity regions of Earth. This reduction in gravity helps keep the suspended particles such as dust in the atmosphere, sand grains in the sea water for longer. Dramatic differences can be seen from the floating dust in the low gravity regions when compared with other regions. The above phenomena can be demonstrated from experiments. The experiments have to be done in high and low gravity regions of the earth during high and low tide, which will assist in comparing the final results. One of the experiments that can be done is by using a water filled cylinder about 80 cm tall, a few particles, which have the same density and same diameter (about 1 mm) and a stop watch. The selected particles were dropped from the surface of the water in the cylinder and the time taken for the particles to reach the bottom of the cylinder was measured using the stop watch. The times of high and low tide charts can be obtained from the regional government authorities. This concept is demonstrated by the particle drop times taken at high and low tides. The result of the experiment shows that the particle settlement time is less in low tide and high in high tide. The experiment for dust particles in air can be collected on filters, which are cellulose ester membranes and using a vacuum pump. The dust on filters can be used to make slides according to the NOHSC method. Counting the dust particles on the slides can be done using a phase contrast microscope. The results show that the concentration of dust is high at high tide and low in low tide. As a result of the high tides, a high concentration of heavy minerals deposit on placer deposits and dust particles retain in the atmosphere for longer in low gravity regions. These conditions are remarkably exhibited in the lowest low gravity region of the earth, mainly in the regions of India, Sri Lanka and in the middle part of the Indian Ocean. The biggest heavy mineral placer deposits are found in coastal regions of India and Sri Lanka and heavy dust particles are found in the atmosphere of India, particularly in the Delhi region.

Keywords: gravity, minerals, tides, moon, costal, atmosphere

Procedia PDF Downloads 126

Authors: Suehyun Cho, Darrell Harrington, Florent Cros, Olin Palmer, John Caputo, Michael Kardosh, Eran Oren, William Loudon, Alex Kiselyov, Michael Shpigelmacher

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The Dandy-Walker malformation (DWM) represents a clinical syndrome manifesting as a combination of posterior fossa cyst, hypoplasia of the cerebellar vermis, and obstructive hydrocephalus. Anatomic hallmarks include hypoplasia of the cerebellar vermis, enlargement of the posterior fossa, and cystic dilatation of the fourth ventricle. Current treatments of DWM, including shunting of the cerebral spinal fluid ventricular system and endoscopic third ventriculostomy (ETV), are frequently clinically insufficient, require additional surgical interventions, and carry risks of infections and neurological deficits. Bionaut Labs develops an alternative way to treat Dandy-Walker Malformation (DWM) associated with non-communicating hydrocephalus. We utilize our discreet microsurgical Bionaut™ particles that are controlled externally and remotely to perform safe, accurate, effective fenestration of the Dandy-Walker cyst, specifically in the posterior fossa of the brain, to directly normalize intracranial pressure. Bionaut™ allows for complex non-linear trajectories not feasible by any conventional surgical techniques. The microsurgical particle safely reaches targets in the lower occipital section of the brain. Bionaut™ offers a minimally invasive surgical alternative to highly involved posterior craniotomy or shunts via direct fenestration of the fourth ventricular cyst at the locus defined by the individual anatomy. Our approach offers significant advantages over the current standards of care in patients exhibiting anatomical challenge(s) as a manifestation of DWM, and therefore, is intended to replace conventional therapeutic strategies. Current progress, including platform optimization, Bionaut™ control, and real-time imaging and in vivo safety studies of the Bionauts™ in large animals, specifically the spine and the brain of ovine models, will be discussed.

Keywords: Bionaut™, cerebral spinal fluid, CSF, cyst, Dandy-Walker, fenestration, hydrocephalus, micro-robot

Procedia PDF Downloads 217

Authors: B. V. Bhaskara Rao, Rodrigo Espinoza

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The rapid development of renewable energy sources has drawn great attention to energy storage devices, especially supercapacitors, because of their high power density and rate performance. This work focus on Fe₃O₄ nanoparticles synthesized by reverse co-precipitation and MWCNTs functionalized by –COOH acid functionalization. The results show that Optimized 25wt% Fe₃O₄@FMWCNT show high specific capacitance 100 mF/cm² at one mA/cm² whereas 15wt% Fe₃O₄@FMWCNT showed high stability (80% retention capacity) over 5000 cycles. The electrolyte used in the coin cell is LiPF6 and the thickness of the electrode is 30 microns. The optimized Fe₃O₄@FMWCNT bucky papers coin cell electrochemical studies suggest that 25wt% Fe₃O₄@FMWCNT could be a good candidate for high-capacity supercapacitor devices. This could be further tested for flexible and planar supercapacitor device application with gel electrolytes.

Keywords: self-standing electrode, Fe₃O4@FMWCNT, supercapacitor, symmetric coin-cell

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Authors: V. Radulescu, S. Dumitru

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Introduction: Determination of the temperature field inside a fluid in motion has many practical issues, especially in the case of turbulent flow. The phenomenon is greater when the solid walls have a different temperature than the fluid. The turbulent heat and mass transfer have an essential role in case of the thermal pollution, as it was the recorded during the damage of the Thermoelectric Power-plant Oradea (closed even today). Basic Methods: Solving the theoretical turbulent thermal pollution represents a particularly difficult problem. By using the semi-empirical theories or by simplifying the made assumptions, based on the experimental measurements may be assured the elaboration of the mathematical model for further numerical simulations. The three zones of flow are analyzed separately: the vicinity of the solid wall, the turbulent transition zone, and the turbulent core. For each area are determined the distribution law of temperature. It is determined the dependence of between the Stanton and Prandtl numbers with correction factors, based on measurements experimental. Major Findings/Results: The limitation of the laminar thermal substrate was determined based on the theory of Landau and Levice, using the assumption that the longitudinal component of the velocity pulsation and the pulsation’s frequency varies proportionally with the distance to the wall. For the calculation of the average temperature, the formula is used a similar solution as for the velocity, by an analogous mediation. On these assumptions, the numerical modeling was performed with a gradient of temperature for the turbulent flow in pipes (intact or damaged, with cracks) having 4 different diameters, between 200-500 mm, as there were in the Thermoelectric Power-plant Oradea. Conclusions: It was made a superposition between the molecular viscosity and the turbulent one, followed by addition between the molecular and the turbulent transfer coefficients, necessary to elaborate the theoretical and the numerical modeling. The concept of laminar boundary layer has a different thickness when it is compared the flow with heat transfer and that one without a temperature gradient. The obtained results are within the margin of error of 5%, between the semi-empirical classical theories and the developed model, based on the experimental data. Finally, it is obtained a general correlation between the Stanton number and the Prandtl number, for a specific flow (with associated Reynolds number).

Keywords: experimental measurements, numerical correlations, thermal pollution through pipelines, turbulent thermal flow

Procedia PDF Downloads 162

Authors: Han Longxiang

Abstract:

In the process of treating industrial oily wastewater with complex components, the traditional treatment methods (flotation, coagulation, microwave heating, etc.) often produce high operating costs, secondary pollution, and other problems. In order to solve these problems, the materials with high flux and stability applied to surfactant-stabilized emulsions separation have gained huge attention in the treatment of oily wastewater. Nevertheless, four stable oil-in-water emulsions can be formed due to different surfactants (surfactant-free, anionic surfactant, cationic surfactant, and non-ionic surfactant), and the previous advanced materials can only separate one or several of them, cannot effectively separate in one step. Herein, a facile synthesis method of graphene-based multilevel filter materials (GMFM) which can efficiently separate the oil-in-water emulsions stabilized with different surfactants only through its gravity. The prepared materials with high stability of 20 cycles show a high flux of ~ 5000 L m-2 h-1 with a high separation efficiency of > 99.9 %. GMFM can effectively separate the emulsion stabilized by mixed surfactants and oily wastewater from factories. The results indicate that the GMFM have a wide range of applications in oil-in-water emulsions separation in industry and environmental science.

Keywords: emulsion, filtration, graphene, one-step

Procedia PDF Downloads 86

Authors: C. F. Alegretti, F. R. Cunha, R. G. Gontijo

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This work investigates the effects of an applied magnetic field on the geometry-driven boundary layer detachment flow of a ferrofluid over a sudden expansion. Both constitutive equation and global magnetization equation for a ferrofluid are considered. Therefore, the proposed formulation consists in a coupled magnetic-hydrodynamic problem. Computational simulations are carried out in order to explore, not only the viability to control flow instabilities, but also to evaluate the consistency of theoretical aspects. The unidirectional sudden expansion in a ferrofluid flow is investigated numerically under the perspective of Ferrohydrodynamics in a two-dimensional domain using a Finite Differences Method. The boundary layer detachment induced by the sudden expansion results in a recirculating zone, which has been extensively studied in non-magnetic hydrodynamic problems for a wide range of Reynolds numbers. Similar investigations can be found in literature regarding the sudden expansion under the magnetohydrodynamics framework, but none considering a colloidal suspension of magnetic particles out of the superparamagnetic regime. The vorticity-stream function formulation is implemented and results in a clear coupling between the flow vorticity and its magnetization field. Our simulations indicate a systematic decay on the length of the recirculation zone as increasing physical parameters of the flow, such as the intensity of the applied field and the volume fraction of particles. The results all are discussed from a physical point of view in terms of the dynamical non-dimensional parameters. We argue that the decrease/reduction in the recirculation region of the flow is a direct consequence of the magnetic torque balancing the action of the torque produced by viscous and inertial forces of the flow. For the limit of small Reynolds and magnetic Reynolds parameters, the diffusion of vorticity balances the diffusion of the magnetic torque on the flow. These mechanics control the growth of the recirculation region.

Keywords: boundary layer detachment, ferrofluid, ferrohydrodynamics, magnetization, sudden expansion

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Authors: M. Rahou, A. J. Andrews, G. Rosengarten

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One of the main challenges in high-temperature solar thermal applications transfer concentrated solar radiation to the load with minimum energy loss and maximum overall efficiency. The use of a solar concentrator in conjunction with bundled optical fibres has potential advantages in terms of transmission energy efficiency, technical feasibility and cost-effectiveness compared to a conventional heat transfer system employing heat exchangers and a heat transfer fluid. In this paper, a theoretical and computer simulation method is described to estimate the net solar radiation transmission from a solar concentrator into and through optical fibres to a thermal application at the end of the fibres over distances of up to 100 m. A key input to the simulation is the angular distribution of radiation intensity at each point across the aperture plane of the optical fibre. This distribution depends on the optical properties of the solar concentrator, in this case, a parabolic mirror with a small secondary mirror with a common focal point and a point-focus Fresnel lens to give a collimated beam that pass into the optical fibre bundle. Since solar radiation comprises a broad band of wavelengths with very limited spatial coherence over the full range of spectrum only ray tracing models absorption within the fibre and reflections at the interface between core and cladding is employed, assuming no interference between rays. The intensity of the radiation across the exit plane of the fibre is found by integrating across all directions and wavelengths. Results of applying the simulation model to a parabolic concentrator and point-focus Fresnel lens with typical optical fibre bundle will be reported, to show how the energy transmission varies with the length of fibre.

Keywords: concentrated radiation, fibre bundle, parabolic dish, fresnel lens, transmission

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Authors: Mokali Veeresham

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In this work, the high-entropy alloy TaNbHfZrTi was processed at room temperature by each step novel reverse rolling up to a 90% reduction in thickness. The reverse rolled 90% samples subsequently used for annealing at 800°C and 1000°C temperatures for 1h to understand phase stability, microstructure, texture, and mechanical properties. The reverse rolled 90% condition contains BCC single-phase; upon annealing at 800°C temperature, the formation of secondary phase BCC-2 prevailed. The partial recrystallization and complete recrystallization microstructures were developed for annealed at 800°C and 1000°C temperatures, respectively. The reverse rolled condition, and 1000°C annealed temperature exhibit extraordinary room temperature tensile properties with high tensile strength (UTS) 1430MPa and 1556 MPa without compromising loss of ductility consists of an appreciable amount of 21% and 20% elongation, respectively.

Keywords: refractory high entropy alloys, reverse rolling, recrystallization, microstructure, tensile properties

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Authors: Mehdi Rezai, Asghar Zamani

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Virtual teams are a reality in today’s fast-paced world. With the possibility of commonly using common resources, an increase of inter-organizational projects, cooperation, outsourcing, and the increase in the number of people who work remotely or flexitime, an extensive and active presence of high-performance teams is a must. Virtual teams are a challenge by themselves. Their members remove the barriers of cultures, time regions and organizations, and they often communicate through electronic devices over considerable distances. Firstly, we examine the management of virtual teams by considering different issues such as cultural and personal diversities, communications and arrangement issues. Then we will examine individuals, processes and the existing tools in a team. The main challenge is managing high-performance virtual teams. First of all, we must examine the concept of performance. Then, we must focus on teams and the best methods of managing them. Constant improvement of performance, together with precisely regulating every individual’s method of working, increases the levels of performance in the course of time. High-performance teams exploit every issue as an opportunity for achieving high performance. And we know that doing projects with high performance is among every organization or team’s objectives. Performance could be measured using many criteria, among which carrying out projects in time, the satisfaction of stakeholders, and not exceeding budgets could be named. Elements such as clear objectives, clearly-defined roles and responsibilities, effective communications, and commitment to collaboration are essential to a team’s effectiveness. Finally, we will examine roles, systems, processes and will carry out a cause-and-effect analysis of different criteria in improving a team’s performance.

Keywords: virtual teams, performance, management, process, improvement, effectiveness

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Authors: Jochen Edmund Kerschenbauer, Roman Salinger, Daniel Strametz

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Insufficient informal communication systems can lead to the first crisis (‘Crisis of Leadership’) for start-ups. Management Control Systems (MCS) are one way for high-technology start-ups to successfully overcome these problems. So far the literature has investigated the incubation of a start-up, but focused less on the post-incubation stage. This paper focuses on the use of MCS in post-incubation and, if failed start-ups agree, on how MCS are used. We conducted 14 semi-structured interviews for this purpose, to obtain our results. The overall conclusion is that the majority of the companies were closed down due to a combination of strategic, operative and financial reasons.

Keywords: closed down, high-technology, incubation, levers of control, management control systems, post-incubation, start-ups

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Authors: Vered Holzmann, Ramzi Halabi

Abstract:

The current research investigates motivators and barriers to high-tech entrepreneurship in the Israeli-Arab Community. With the aim to exploit the capacity of Israel as a 'start-up nation', we identify the most important aspects to promote integration of Israeli-Arab entrepreneurs in high-tech startups and business companies, thus impact the socio-economic status of the Arab community in Israel. We reviewed the literature on the role of high-tech and entrepreneurship in the Israeli economy, the profile of the Israeli-Arab community with regard to education and employability, and the characteristics of minority entrepreneurship to understand entrepreneurs' intentions, their incentives to choose the entrepreneurial route on one hand and the obstacles that they face on the other hand. Based on the literature review, we conducted an integrated study that included a survey among 73 Israeli-Arabs involved in high-tech entrepreneurship and 16 semi-structured interviews with Israeli-Arab and Jewish entrepreneurs and leaders in the high-tech industry. We analyzed the data to explore personal and social motivating factors to entrepreneurship as well as educational and socio-economical barriers for entrepreneurship. Three major elements were found to be the most influential on Arab high-tech entrepreneurship in Israel: education, financial resources, and strategic-institutional support. The relationship between education and employability that is well-known with regard to general education, requires two additional aspects in the field of high-tech entrepreneurship: education of technology and engineering, and education of business and entrepreneurship. The study findings reveal that the main motivation factors for entrepreneurship are development of creative ideas and improvement of the socio-economic status, while financial-related factors and lack of institutional and governmental support are perceived as impediments to entrepreneurial activities. Financing difficulties are mainly derived from discriminating financial environment and lack of professional networking. The relationship between entrepreneurship and economic growth seems to be clear and simple; thus it is a national interest to encourage entrepreneurship among the Arab community, and especially high-tech entrepreneurship which has a significant role in the economic growth of Israel.

Keywords: high-tech industry, innovation management, Israeli-Arab community, minority entrepreneurship, motivating factors and barriers

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Authors: Mehmet Eren Çelik

Abstract:

Values are notions that help people to decide what is good or not and to direct their attitude. Teaching values has always been very important throughout the history. Values should be thought in younger ages to get more efficiency. Therefore military schools are the last stop to learn values effectively. That’s why values education in military schools has vital importance. In this study the military side of values education is examined. The purpose of the study is to show how important values education is and why military students need values education. First of all what value is and what values education means is clearly explained and values education in schools and specifically in military schools is stated. Then values education in Işıklar Air Force High School exemplifies the given information.

Keywords: Işıklar Air Force High School, military school, values, values education

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Authors: Ana Bermudez de Castro Muela, Xiomara Santos Salas, Silvia Cayon Somacarrera

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The aim of this review is to explain what is the intracranial hypotension and its main causes, and also to approach to the diagnostic management in the different clinical situations, understanding radiological findings, and physiopathological substrate. An approach to the diagnostic management is presented: what are the guidelines to follow, the different tests available, and the typical findings. We review the myelo-CT and myelo-RM studies in patients with suspected CSF fistula or hypotension of unknown cause during the last 10 years in three centers. Signs of intracranial hypotension (subdural hygromas/hematomas, pachymeningeal enhancement, venous sinus engorgement, pituitary hyperemia, and lowering of the brain) that are evident in baseline CT and MRI are also sought. The intracranial hypotension is defined as a lower opening pressure of 6 cmH₂O. It is a relatively rare disorder with an annual incidence of 5 per 100.000, with a female to male ratio 2:1. The clinical features it’s an orthostatic headache, which is defined as development or aggravation of headache when patients move from a supine to an upright position and disappear or typically relieve after lay down. The etiology is a decrease in the amount of cerebrospinal fluid (CSF), usually by loss of it, either spontaneous or secondary (post-traumatic, post-surgical, systemic disease, post-lumbar puncture etc.) and rhinorrhea and/or otorrhea may exist. The pathophysiological mechanisms of hypotension and CSF hypertension are interrelated, as a situation of hypertension may lead to hypotension secondary to spontaneous CSF leakage. The diagnostic management of intracranial hypotension in our center includes, in the case of being spontaneous and without rhinorrhea and/or otorrhea and according to necessity, a range of available tests, which will be performed from less to more complex: cerebral CT, cerebral MRI and spine without contrast and CT/MRI with intrathecal contrast. If we are in a situation of intracranial hypotension with the presence of rhinorrhea/otorrhea, a sample can be obtained for the detection of b2-transferrin, which is found in the CSF physiologically, as well as sinus CT and cerebral MRI including constructive interference steady state (CISS) sequences. If necessary, cisternography studies are performed to locate the exact point of leakage. It is important to emphasize the significance of myelo-CT / MRI to establish the diagnosis and location of CSF leak, which is indispensable for therapeutic planning (whether surgical or not) in patients with more than one lesion or doubts in the baseline tests.

Keywords: cerebrospinal fluid, neuroradiology brain, magnetic resonance imaging, fistula

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Authors: C. Jouhar, B. Rajesh Kamath, M. K. Veeraiah, M. Z. Kurian

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Since long time ago, petroleum-based mineral oils have been used for liquid insulation in high voltage equipments. Mineral oils are widely used as insulation for transmission and distribution power transformers, capacitors and other high voltage equipment. Petroleum-based insulating oils have excellent dielectric properties such as high electric field strength, low dielectric losses and good long-term performance. Due to environmental consideration, an attempt to search the alternate liquid insulation is required. The influence of particles on the voltage breakdown in insulating oil and other liquids has been recognized for many years. Particles influence both AC and DC voltage breakdown in insulating oil. Experiments are conducted under AC voltage. The breakdown process starts with a microscopic bubble, an area of large distance where ions or electrons initiate avalanches. Insulating liquids drive their dielectric strength from the much higher density compare to gases. Experiments are carried out under High Voltage AC (HVAC) in different types of oils namely castor oil, vegetable oil and mineral oil. The Breakdown Voltage (BDV) with presence of moisture and particle contamination in different types of oils is studied. The BDV of vegetable oil is better when compared to other oils without contamination. The BDV of mineral oil is better when compared to other types of oils in presence of contamination.

Keywords: breakdown voltage, high voltage AC, insulating oil, oil breakdown

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Authors: Hee-Choul Kwon, Hyungjin Cho, Heeyong Kwon

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Image rotation is one of main pre-processing step in image processing or image pattern recognition. It is implemented with rotation matrix multiplication. However it requires lots of floating point arithmetic operations and trigonometric function calculations, so it takes long execution time. We propose a new high speed image rotation algorithm without two major time-consuming operations. We compare the proposed algorithm with the conventional rotation one with various size images. Experimental results show that the proposed algorithm is superior to the conventional rotation ones.

Keywords: high speed rotation operation, image processing, image rotation, pattern recognition, transformation matrix

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Authors: Jung-Ho Moon, Tae Kwon Ha

Abstract:

M2 steels, the typical Co-free high speed steel (HSS) possessing hardness level of 63~65 HRc, are most widely used for cutting tools. On the other hand, Co-containing HSS’s, such as M35 and M42, show a higher hardness level of 65~67 HRc and used for high quality cutting tools. In the fabrication of HSS’s, it is very important to control cleanliness and eutectic carbide structure of the ingot and it is required to increase productivity at the same time. Production of HSS ingots includes a variety of processes such as casting, electro-slag remelting (ESR), forging, blooming, and wire rod rolling processes. In the present study, electro-slag rapid remelting (ESRR) process, an advanced ESR process combined by continuous casting, was successfully employed to fabricate HSS billets of M2, M35, and M42 steels. Distribution and structure of eutectic carbides of the billets were analysed and cleanliness, hardness, and composition profile of the billets were also evaluated.

Keywords: high speed tool steel, eutectic carbide, microstructure, hardness, fracture toughness

Procedia PDF Downloads 439

Authors: Nisha Thapa, Ram Prasad Mainali, Prakriti Chand

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Broadleaf mustard is a commercialized leafy vegetable of Nepal. However, its utilization is hindered in terms of production and productivity due to the high intensity of insects, pests, and diseases causing great loss. The plant protection part of the crop’s disease and damage intensity has not been studied much from research perspectives in Nepal. The research aimed to evaluate broadleaf mustard genotypes for resistance against different diseases. A total of 35 native genotypes of broadleaf mustard were screened at weekly intervals by scoring the plants for ten weeks. Five different diseases, such as Rhizoctonia root rot, Alternaria blight, black rot, turnip mosaic virus disease, and white rust, were reported from the broad leaf mustard genotypes. Out of 35 genotypes, 23 genotypes were found with very high Rhizoctonia Root Rot severity, whereas 8 genotypes showed very high Alternaria blight severity. Likewise, 3 genotypes were found with high Black rot severity, and 1 genotype was found with very high Turnip mosaic virus disease incidence. Similarly, 2 genotypes were found to have very high White rust severity. Among the disease of national importance, Rhizoctonia root rot was found to be the most severe disease with the greatest loss. Broadleaf mustard genotypes like Rato Rayo, CO 1002, and CO 11007 showed average to the high level of field resistance; therefore, these genotypes should be used, conserved, and stored in a mustard improvement program as the disease resistance quality or susceptibility of these genotypes can be helpful for seed producing farmers, companies and other stakeholders through varietal improvement and developmental works that further aids in sustainable disease management of the vegetable.

Keywords: genotype, disease resistance, Rhizoctonia root rot severity, varietal improvement

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Authors: Kadda Boumediene, Mohamed Bouzit

Abstract:

The prediction of the flow around marine propellers and vessel hulls propeller interaction is one of the challenges of Computational fluid dynamics (CFD). The CFD has emerged as a potential tool in recent years and has promising applications. The objective of the current study is to predict the hydrodynamic performances of HSP marine propeller in open water and behind a vessel. The unsteady 3-D flow was modeled numerically along with respectively the K-ω standard and K-ω SST turbulence models for steady and unsteady cases. The hydrodynamic performances such us a torque and thrust coefficients and efficiency show good agreement with the experiment results.

Keywords: seiun maru propeller, steady, unstead, CFD, HSP

Procedia PDF Downloads 300