Search results for: Phase angle shift

Authors: Ju Hyun Won, Seok Hong Min, Tae Kwon Ha

Abstract:

Phase equilibria of AZ91D Mg alloys for nonflammable use, containing Ca and Y, were carried out by using FactSage® and FTLite database, which revealed that solid solution treatment, could be performed at temperatures from 400 to 450 °C. Solid solution treatment of AZ91D Mg alloy without Ca and Y was successfully conducted at 420 °C and supersaturated microstructure with all beta phase resolved into matrix was obtained. In the case of AZ91D Mg alloy with some Ca and Y, however, a little amount of intermetallic particles were observed after solid solution treatment. After solid solution treatment, each alloy was annealed at temperatures of 180 and 200 °C for time intervals from 1 min to 48 hrs and hardness of each condition was measured by micro-Vickers method. Peak aging conditions were deduced as at the temperature of 200 °C for 10 hrs.

Keywords: Mg alloy, AZ91D, nonflammable alloy, phase equilibrium, peak aging

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Authors: P. Pistelok

Abstract:

The article presents the concept of an electromagnetic circuit generator with permanent magnets mounted on the surface rotor core designed for single phase work. Computation field-circuit model was shown. The spectrum of time course of voltages in the idle work was presented. The cross section with graphically presentation of magnetic induction in particular parts of electromagnetic circuits was presented. Distribution of magnetic induction at the rated load point for each phase were shown. The time course of voltages and currents for each phases for rated power were displayed. An analysis of laboratory results and measurement of load characteristics of the generator was discussed. The work deals with three electromagnetic circuits of generators with permanent magnet where output voltage characteristics versus rated power were expressed.

Keywords: permanent magnet generator, permanent magnets, vibration, course of torque, single phase work, asymmetrical three phase work

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Authors: Sudha Bhutada, S. R. Nigam

Abstract:

In this paper, a single-phase PV inverter applying a dual boost converter circuit inverter is proposed for photovoltaic (PV) generation system and PV grid connected system. This system is designed to improve integration of a Single phase inverter with Photovoltaic panel. The DC 24V is converted into to 86V DC and then 86V DC to 312V DC. The 312 V DC is then successfully inverted to AC 220V. Hence, solar energy is powerfully converted into electrical energy for fulfilling the necessities of the home load, or to link with the grid. Matlab Simulation software was used for simulation of the circuit and outcome are presented in this paper.

Keywords: H bridge inverter, dual boost converter, PWM, SPWM

Procedia PDF Downloads 639

Authors: H. Shokouhmand, A. Ghanami

Abstract:

A heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At a hot surface of the heat pipe, the liquid phase absorbs heat and changes to the vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to the liquid phase. Due to gravitational force the liquid phase flows to the evaporator section. In HVAC systems, the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses the heater, humidifier, or dryer is a suitable nominate for the utilization of heat pipes. Generally, heat pipes have three main sections: condenser, adiabatic region, and evaporator. Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In the present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of the heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian-Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances its heat transfer capacity.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

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Authors: Mehdi Modabberifar, Milad Roodi, Ehsan Souri

Abstract:

In recent years, honeycomb fiber reinforced plastic (FRP) sandwich panels have been increasingly used in various industries. Low weight, low price, and high mechanical strength are the benefits of these structures. However, their mechanical properties and behavior have not been fully explored. The objective of this study is to conduct a combined numerical-statistical investigation of honeycomb FRP sandwich beams subject to torsion load. In this paper, the effect of geometric parameters of the sandwich panel on the maximum shear strain in both face and core and angle of torsion in a honeycomb FRP sandwich structures in torsion is investigated. The effect of Parameters including core thickness, face skin thickness, cell shape, cell size, and cell thickness on mechanical behavior of the structure were numerically investigated. Main effects of factors were considered in this paper and regression equations were derived. Taguchi method was employed as experimental design and an optimum parameter combination for the maximum structure stiffness has been obtained. The results showed that cell size and face skin thickness have the most significant impacts on torsion angle, maximum shear strain in face and core.

Keywords: finite element, honeycomb FRP sandwich panel, torsion, civil engineering

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Authors: Iuliia Riabenko, Konstantin Beloshenko, Sergey Shulga, Valeriy Shulga

Abstract:

An optical system has been developed consisting of a TIR lens and an aspherical surface designed to collect Stokes radiation from biomolecules. The freeform material is SYLGARD-184, which provides a low level of noise associated with the luminescence of the substrate. The refractive index of SYLGARD-184 is 1.4028 for a wavelength of 632 nm, the Abbe number is 72, these material parameters make it possible to design the desired shape for the wavelength range of 640-700 nm. The system consists of a TIR lens, inside which is placed a high-quality resonant system consisting of a biomolecule and a metal colloid. This system can be described using the coupled oscillator model. The laser excitation radiation was fed through the base of the TIR lens. The sample was mounted inside the TIR lens at a distance of 8 mm from the base. As a result of Raman scattering of laser radiation, a Stokes bend appeared from the biolayer. The task of this work was that it was necessary to collect this radiation emitted at a 4π steradian angle. For this, an internal aspherical surface was used, which made it possible to defocus the beam emanating from the biolayer and direct its radiation to the borders of the TIR lens at the Brewster angle. The collated beam of Stokes radiation contains 97% of the energy scattered by the biolayer. Thus, a simple scheme was proposed for collecting and collimating the Stokes radiation of biomolecules.

Keywords: TIR lens, freeform material, raman scattering, biolayer, brewster angle

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Authors: Amanda Cristina de Oliveira, Elias de Souza Monteiro Filho, Roberta Ceriani

Abstract:

Liquid-liquid extraction in aqueous two-phase systems (ATPSs) constitutes a powerful tool for purifying bio-materials, such as cells, organelles, proteins, among others. In this work, the extraction of the bovine serum albumin (BSA) has been studied in systems formed by polyethylene glycol (PEG) (1500, 4000, and 6000 g.mol⁻¹) + potassium sodium tartrate + water at 303.15°K. Phase diagrams were obtained by turbidimetry and Merchuk’s method (1998). The experimental tie-lines were described using the Othmer-Tobias and Bancroft correlations. ATPSs were correlated with the nonrandom two-liquid (NRTL) model. The results were considered excellent according to global root-mean-square deviations found which were between 0,72 and 1,13%. The concentrations of the proteins in each phase were determined by spectrophotometry at 280 nm, finding partition efficiencies greater than 71%.

Keywords: aqueous two phases systems, bovine serum albumin , liquid-liquid extraction, polyethylene glycol

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Authors: Camille Rault, Mark Bahr

Abstract:

The aim of the present study was to develop a contemporaneous instrument measuring adolescent’s subjective well-being (SWB). The instrument development underwent a three-phase pilot study. Phase one (N = 31) used a qualitative approach to generate domains of SWB relevant to adolescents. During the second phase (N = 22), items were tested targeting these domains. Finally, the third phase (N = 22) assisted in addition, deletion and refinement according to the first two phases of the pilot. A total of 49 items were retained for the final version of the instrument. The Contemporary Adolescent Well-Being Scale (CAWBS) was administered to 1071 school children (599 girls) aged between ten to 18 years old (M = 14,70; SD = 1.45) from Queensland, Australia. Results confirmed the seven-factor construct hypothesized and explained 45% of the variance. The questionnaire pertained to seven domains of adolescent’s SWB, namely; Overall life satisfaction; Bullying; Body image; Social connectedness; Activities; Control appraisal; and Negative feelings. Reliability was shown to be acceptable with Cronbach’s alpha ranging from .58 to .89. Future research should refine the CAWBS and investigate the psychometric properties of this instrument.

Keywords: adolescence, construct validity, instrument, subjective well-being

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Authors: Mohammad Sadegh Narges, Zahra Ghadampour

Abstract:

Due to the specific condition, offshore pipelines are given careful consideration and care in both design and operation. Most of the offshore pipeline flows are multi-phase. Multi-phase flows construct different pattern or flow regimes (in simultaneous gas-liquid flow, flow regimes like slug flow, wave and …) under different circumstances. One of the influencing factors on the flow regime is the pipeline roughness value. So far, roughness value influences and the sensitivity of the present models to this parameter have not been taken into consideration. Therefore, roughness value influences on the flow regimes in offshore pipelines are discussed in this paper. Results showed that geometry, absolute pipeline roughness value (materials that the pipeline is made of) and flow phases prevailing the system are of the influential parameters on the flow regimes prevailing multi-phase pipelines in a way that a change in any of these parameters results in a change in flow regimes in all or part of the pipeline system.

Keywords: absolute roughness, flow regime, multi-phase flow, offshore pipelines

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Authors: Bindu I. Somarajan, Viney Gupta, Gagandeep Kaur Walia, Jasbir Kaur, Sunil Kumar, Shikha Gupta, Abadh K. Chaurasia, Dinesh Gupa, Abhinav Kaushik, Aditi Mehta, Vipin Gupta, Arundhati Sharma

Abstract:

Background: Juvenile onset primary open angle glaucoma (JOAG), affects individuals under the age of 40 years. Studies on a few families of JOAG, that led to the discovery of the Myocilin gene, reported the disease to have an autosomal dominant pattern of inheritance. However, sporadic forms of JOAG been seen to be more common in some populations. Most pathological homozygous mutations in the CYP1B1 gene associated with JOAG have been seen among sporadic cases. Given the higher prevalence of sporadic JOAG cases in our population, we aimed to look for common mutations E229K and R368H, the two most common variants in the CYP1B1 gene associated with glaucoma. Objective: To determine the frequency and evaluate genotype phenotype correlation of CYP1B1 E229K and R368H mutations in a cohort of 120 sporadic Juvenile open angle glaucoma patients.Methods: Unrelated JOAG patients whose first degree relatives had been examined and found to be unaffected were included in the study. The patients and their parents were screened for E229K and R368H mutations. The phenotypic characteristics were compared between probands with and with out these mutations by SPSS v16. Results: Out of 120 JOAG patients included in the study, the E229K mutation was seen in 9 probands (7.5%) and R368H in 7 (5.8%). The average age of onset of the disease (p=0.3) and the highest untreated IOP (p=0.4) among those carrying mutations was not significantly different from those who did not have these mutations. The proportion of probands with angle dysgenesis among those with E229K and R368H mutations was 70% (11 out of 16) in comparison to 65% (67 out of 104) of those who did not harbour these mutations (p=0.56). Similarly the probands with moderate to high myopia among those with E229K and R368H mutations was 20% (3 out of 16) in comparison to 18% (18 out of 104) of those who did not harbour these mutations(p=0.59). Conclusion: The frequency of E229K and R368H mutations of the CYP1B1 gene is low even among sporadic JOAG patients. Moreover there is no clinical correlation between the presence of these mutations and disease severity

Keywords: CYP1B1, gene, IOP, JOAG, mutation

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Authors: Bolanle Deborah Motilewa, E.K. Rowland Worlu, Gbenga Mayowa Agboola, Marvellous Aghogho Chidinma Gberevbie

Abstract:

Businesses operating in the modern business world are faced with varying challenges; amongst which is the need to ensure that they are performing their societal function of being responsible in the society in which they operate. This responsibility to society is generally termed as corporate social responsibility. For many years, the practice of corporate social responsibility (CSR) was solely philanthropic, where organizations gave ‘charity’ or ‘alms’ to society, without any link to the organization’s mission and objectives. However, there has arisen a shift in the application of CSR from an act of philanthropy to a strategy with a business model engaged in by organizations to create a win-win situation of performing their societal obligation, whilst simultaneously performing their economic obligation. In more recent times, the term has moved from CSR to creating shared value, which is simply corporate policies and practices that enhance the competitiveness of a business organization while simultaneously advancing social and economic conditions in the communities in which the company operates. Creating shared value has in more recent light found more meaning in underdeveloped countries, faced with deep societal challenges that businesses can solve whilst creating economic value. This study thus reviews literature on CSR, conceptualizing the shift to creating shared value and finally viewing its potential significance in Africa’s development.

Keywords: africapitalism, corporate social responsibility, development, shared value

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Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section. In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity used in the abstract.

Keywords: heat pipe, HVAC system, grooved heat pipe, CFD simulation

Procedia PDF Downloads 419

Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section.In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity used in the abstract.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

Procedia PDF Downloads 359

Authors: A. Haddick, A. Soltan

Abstract:

Background: During the period of recovery from an operative obstetric procedure, a woman is not only at risk of the life-threatening complications accompanying labour but also those associated with surgery and anaesthesia. It is speculated that women in the recovery area may receive a lower standard of care over a night shift. Thus obstetric recovery room care should be evaluated regularly to ensure all women receive an equally high standard of care 24/7. Aim: The aim of this audit was to undertake an audit in the Liverpool Women’s Hospital on the care in recovery, and to ascertain the extent to which the standards were met. This audit included the full audit cycle. Method: Standards were taken from the AAGBI, RCOA, NICE and CNST guidelines. There were 12 standards including appropriate documentation of vital signs and appropriate length of stay after surgery. Notes from 100 patients were analysed from March 2011-March 2012. There were 52 day notes and 48 night notes; these were accessed to gain the relevant data. In the re audit 35 notes were accessed from March 14-September 14. Results: The Liverpool Women’s Hospital met in total 10 of these standards. 10 were met during the day shift (83%) and 0 met during the night shift. In the re audit, there was a significant improvement in the standards met at night. 9 of the standards were met during the day and 7 of the standards were met at night. Clearly there are still improvements to be made. Conclusions: In the original audit, an audit action plan was formulated. This was following discussion of the results of this audit in an MDT meeting and presentation with a consultant Obstetrician, the head of Midwifery, the head of Obstetrics theatres and a recovery nurse. This audit will be further discussed in the Liverpool Woman's Hospital in July 2015 for further implementation for improvement.

Keywords: care, recovery, room, women

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Authors: Saifon Chongthub

Abstract:

The purpose of this research is to synthesize adsorbent foam for CO2 adsorption. The polymer was prepared from poly High Internal Phase Emulsion (PolyHIPE) using styrene as monomer and divinylbenzene as comonomer. Its morphology was determined by Scanning Electron Microscopy (SEM). To further increased CO2 adsorption of the prepared polyHIPE, the layer by layer (LbL) technique was applied, which alternated polyelectrolyte injection between layers of Poly(styrenesulfonate) (PSS) and Poly(diallyldimetyl-ammonium chloride)(PDADMAC) as primary layer, and layers of PSS and polyetyleneimine (PEI) as secondary layer.

Keywords: high internal phase emulsion, polyHIPE, surface modification, layer by layer technique, CO2 adsorption

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Authors: S. K. Jain, M. K. Mishra

Abstract:

Oblique propagation of ion-acoustic solitons in magnetized electron-positron-ion (EPI) plasma with warm adiabatic ions and isothermal electrons has been studied. Korteweg-de Vries (KdV) equation using reductive perturbation method has been derived for the system, which admits an obliquely propagating soliton solution. It is found that for the selected set of parameter values, the system supports only compressive solitons. Investigations reveal that an increase in positron concentration diminishes the amplitude as well as the width of the soliton. It is also found that the temperature ratio of electron to positron (γ) affects the amplitude of the solitary wave. An external magnetic field do not affect the amplitude of ion-acoustic solitons, but obliqueness angle (θ), the angle between wave vector and magnetic field affects the amplitude. The amplitude of the ion-acoustic solitons increases with increase in angle of obliqueness. Magnetization and obliqueness drastically affect the width of the soliton. An increase in ionic temperature decreases the amplitude and width. For the fixed set of parameters, profiles have been drawn to study the combined effect with variation of two parameters on the characteristics of the ion-acoustic solitons (i.e., amplitude and width). The result may be applicable to plasma in the laboratory as well as in the magnetospheric region of the earth.

Keywords: ion-acoustic solitons, Korteweg-de Vries (KdV) equation, magnetized electron-positron-ion (EPI) plasma, reductive perturbation method

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Authors: Fathi Abubrig, Mohamed Delfag, Suad Abuzariba

Abstract:

The influence of the crystal field interactions on the mixed spin-3/2 and spin-5/2 ferromagnetic Ising system is considered by using the mean field theory based on Bogoliubov inequality for the Gibbs free energy. The ground-state phase diagram is constructed, the phase diagrams of the second-order critical temperatures are obtained, and the thermal variation of the sublattice magnetizations is investigated in detail. We find some interesting phenomena for the sublattice magnetizations at particular values of the crystal field interactions.

Keywords: crystal field, Ising system, ferromagnetic, magnetization, phase diagrams

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Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section.In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity.

Keywords: heat pipe, HVAC system, grooved Heat pipe, heat pipe limits

Procedia PDF Downloads 415

Authors: Khelifa Tarek, Benmebarek Sadok

Abstract:

The 2D passive earth pressures acting on rigid retaining walls problem has been widely treated in the literature using different approaches (limit equilibrium, limit analysis, slip line and numerical computation), however, the 3D passive earth pressures problem has received less attention. This paper is concerned with the numerical study of 3D passive earth pressures induced by the translation of a rigid rough retaining wall for associated and non-associated soils. Using the explicit finite difference code FLAC3D, the increase of the passive earth pressures due to the decrease of the wall breadth is investigated. The results given by the present numerical analysis are compared with other investigation. The influence of the angle of dilation on the coefficients is also studied.

Keywords: numerical modeling, FLAC3D, retaining wall, passive earth pressures, angle of dilation

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Authors: Eni Rahmi, Rasmi Rikmasari, Taufik Soemarsongko

Abstract:

Background: One of the bad habits that requires a treatment and viewed as a risk factor of the temporomandibular disorder is bruxism. Bruxism defined as an awake and/or asleep parafunctional activities include grinding, gnashing, bracing or clenching of the teeth. In particular circumstances such as an increased frequency of episode, duration and the intensity of masseter contractions, caused phenomenon with pathological consequences, i.e., mandibular remodeling. The remodeling in mandibular angle was associated with the masseter and pterygoid medial muscles attachment which in its insertion area. The aim of this study was to compare the mandibular remodeling between bruxers and non-bruxers with ramus height, gonial angle and bigonial width as parameters, and to identify correlation among those parameters in bruxers, using panoramic radiographic. Methods: This study was conducted on 35 bruxers (10 phasic bruxism patients, 6 tonic bruxism patients, and 19 mixed bruxism patients) and 20 non-bruxers as control group. The data were obtained by using questionary, clinical examination, and radiographic measurement. Panoramic radiograph measurement was done using soft CBCT EPX Impla (E-Woo Korea). The data was analyzed by using Paired T-Test to see differences between parameters in both group and Pearson Correlation Test to evaluate correlation among parameters. Result: There was significant differences between bruxers and non-bruxers in ramus heights (p=0,04), bigonial widths (p=0,001), and gonial angles(p=0,015). The bruxers showed increased ramus heights and bigonial widths, in other hand, the gonial angles decreased. This study also found that there was highly correlation among ramus height, gonial angles, and bigonial widths. Conclusion: the bone remodeling occurred on inferior and posterior border of mandibular angle in bruxism patient, indicated by the form and size differences between bruxers (phasic bruxism, tonic bruxism, and mixed bruxism) with non-bruxers, which shown by panoramic radiograph.

Keywords: bruxism, ramus height, gonial angle, bigonial width

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Authors: Yusuf Yilmaz, Gamze Gediz Ilis

Abstract:

Gas Nitrogen where has a boiling point of -189.52oC at atmospheric pressure widely used in the industry. Nitrogen that used in the industry should be transported in liquid form to the plant area. Ambient air vaporizer (AAV) generally used for vaporization of cryogenic gases such as liquid nitrogen (LN2), liquid oxygen (LOX), liquid natural gas (LNG), and liquid argon (LAR) etc. AAV is a group of star-shaped fin vaporizer. The design and the effect of the shape of fins of the vaporizer is one of the most important criteria for the performance of the vaporizer. In this study, the performance of AAV working with liquid nitrogen was analyzed numerically in a star-shaped aluminum finned pipe. The numerical analysis is performed in order to investigate the heat capacity of the vaporizer per meter pipe length. By this way, the vaporizer capacity can be predicted for the industrial applications. In order to achieve the validation of the numerical solution, the experimental setup is constructed. The setup includes a liquid nitrogen tank with a pressure of 9 bar. The star-shaped aluminum finned tube vaporizer is connected to the LN2 tank. The inlet and the outlet pressure and temperatures of the LN2 of the vaporizer are measured. The mass flow rate of the LN2 is also measured and collected. The comparison of the numerical solution is performed by these measured data. The ambient conditions of the experiment are given as boundary conditions to the numerical model. The surface tension and contact angle have a significant effect on the boiling of liquid nitrogen. Average heat transfer coefficient including convective and nucleated boiling components should be obtained for liquid nitrogen saturated flow boiling in the finned tube. Fluent CFD module is used to simulate the numerical solution. The turbulent k-ε model is taken to simulate the liquid nitrogen flow. The phase change is simulated by using the evaporation-condensation approach used with user-defined functions (UDF). The comparison of the numerical and experimental results will be shared in this study. Besides, the performance capacity of the star-shaped finned pipe vaporizer will be calculated in this study. Based on this numerical analysis, the performance of the vaporizer per unit length can be predicted for the industrial applications and the suitable pipe length of the vaporizer can be found for the special cases.

Keywords: liquid nitrogen, numerical modeling, two-phase flow, cryogenics

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Authors: A. Ghanami, M.Heydari

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section. In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator. Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity.used in the abstract.

Keywords: Heat pipe, HVAC system, Grooved Heat pipe, Heat pipe limits.

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Authors: Mohammad Mahdi Doustdar, Mohammad Mojtahedpoor

Abstract:

The effects of flame-holder position, the ratio of flame holder diameter to combustion chamber diameter and injection angle on fuel propulsive droplets sizing and effective mass fraction have been studied by a cold flow. We named the mass of fuel vapor inside the flammability limit as the effective mass fraction. An empty cylinder as well as a flame-holder which are as a simulator for duct combustion has been considered. The airflow comes into the cylinder from one side and injection operation will be done by four nozzles which are located on the entrance of cylinder. To fulfill the calculations a modified version of KIVA-3V code which is a transient, three-dimensional, multi phase, multi component code for the analysis of chemically reacting flows with sprays, is used.

Keywords: KIVA-3V, flame-holder, duct combustion, effective mass fraction, mean diameter of droplets

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Authors: Kholood A. Baron

Abstract:

While radiologist numbers specialized in spine interventional procedures are limited in Kuwait, the number of patients demanding these procedures is increasing rapidly. Due to this high demand, the workload of radiologists is increasing, which might represent a radiation exposure concern. During these procedures, the doctor’s hands are in very close proximity to the main radiation beam/ if not within it. The aim of this study is to measure the radiation dose for radiologists during several interventional procedures for the spine. Methods: Two doctors carrying different workloads were included. (DR1) was performing procedures in the morning and afternoon shifts, while (DR2) was performing procedures in the morning shift only. Comparing the radiation exposures that the hand of each doctor is receiving will assess radiation safety and help to set up workload regulations for radiologists carrying a heavy schedule of such procedures. Entrance Skin Dose (ESD) was measured via TLD (ThermoLuminescent Dosimetry) placed at the right wrist of the radiologists. DR1 was covering the morning shift in one hospital (Mubarak Al-Kabeer Hospital) and the afternoon shift in another hospital (Dar Alshifa Hospital). The TLD chip was placed in his gloves during the 2 shifts for a whole week. Since DR2 was covering the morning shift only in Al Razi Hospital, he wore the TLD during the morning shift for a week. It is worth mentioning that DR1 was performing 4-5 spine procedures/day in the morning and the same number in the afternoon and DR2 was performing 5-7 procedures/day. This procedure was repeated for 4 consecutive weeks in order to calculate the ESD value that a hand receives in a month. Results: In general, radiation doses that the hand received in a week ranged from 0.12 to 1.12 mSv. The ESD values for DR1 for the four consecutive weeks were 1.12, 0.32, 0.83, 0.22 mSv, thus for a month (4 weeks), this equals 2.49 mSv and calculated to be 27.39 per year (11 months-since each radiologist have 45 days of leave in each year). For DR2, the weekly ESD values are 0.43, 0.74, 0.12, 0.61 mSv, and thus, for a month, this equals 1.9 mSv, and for a year, this equals 20.9 mSv /year. These values are below the standard level and way below the maximum limit of 500 mSv per year (set by ICRP = International Council of Radiation Protection). However, it is worth mentioning that DR1 was a senior consultant and hence needed less fluoro-time during each procedure. This is evident from the low ESD values of the second week (0.32) and the fourth week (0.22), even though he was performing nearly 10-12 procedures in a day /5 days a week. These values were lower or in the same range as those for DR2 (who was a junior consultant). This highlighted the importance of increasing the radiologist's skills and awareness of fluoroscopy time effect. In conclusion, the radiation dose that radiologists received during spine interventional radiology in our setting was below standard dose limits.

Keywords: radiation protection, interventional radiology dosimetry, ESD measurements, radiologist radiation exposure

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Authors: Nazli Hardy

Abstract:

Multidisciplinary application of computer science, interactive database-driven web application, the Internet of Things (IoT) represents a digital ecosystem that has pervasive technological, social, and economic, impact on the human population. It is a long-term technology, and its development is built around the connection of everyday objects, to the Internet. It is estimated that by 2020, with billions of people connected to the Internet, the number of connected devices will exceed 50 billion, and thus IoT represents a paradigm shift in in our current interconnected ecosystem, a communication shift that will unavoidably affect people, businesses, consumers, clients, employees. By nature, in order to provide a cohesive and integrated service, connected devices need to collect, aggregate, store, mine, process personal and personalized data on individuals and corporations in a variety of contexts and environments. A significant factor in this paradigm shift is the necessity for secure and appropriate transmission, processing and storage of the data. Thus, while benefits of the applications appear to be boundless, these same opportunities are bounded by concerns such as trust, privacy, security, loss of control, and related issues. This poster and presentation look at a multi-factor authentication (MFA) mechanisms that need to change from the login-password tuple to an Identity and Access Management (IAM) model, to the more cohesive to Identity Relationship Management (IRM) standard. It also compares and contrasts messaging protocols that are appropriate for the IoT ecosystem.

Keywords: Internet of Things (IoT), authentication, protocols, survey

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Authors: Radouane Elbahjaoui, Hamid El Qarnia

Abstract:

Melting of Paraffin Wax (P116) dispersed with Al₂O₃ nanoparticles in a rectangular latent heat storage unit (LHSU) is numerically investigated. The storage unit consists of a number of vertical and identical plates of nano-enhanced phase change material (NEPCM) separated by rectangular channels in which heat transfer fluid flows (HTF: Water). A two dimensional mathematical model is considered to investigate numerically the heat and flow characteristics of the LHSU. The melting problem was formulated using the enthalpy porosity method. The finite volume approach was used for solving equations. The effects of nanoparticles’ volumetric fraction and the Reynolds number on the thermal performance of the storage unit were investigated.

Keywords: nano-enhanced phase change material (NEPCM), phase change material (PCM), nanoparticles, latent heat storage unit (LHSU), melting.

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Authors: Piotr Wisniewski, Sławomir Dykas

Abstract:

Condensation has a negative impact on turbomachinery efficiency in many energy processes.In technical applications, it is often impossible to dry the working fluid at the nozzle inlet. One of the most popular working fluid is atmospheric air that always contains water in form of steam, liquid, or ice crystals. Moreover, it always contains some amount of suspended particles which influence the phase change process. It is known that the phenomena of evaporation or condensation are connected with release or absorption of latent heat, what influence the fluid physical properties and might affect the machinery efficiency therefore, the phase transition has to be taken under account. This researchpresents an attempt to evaluate the impact of solid and liquid particles suspended in the air on the expansion of moist air in a low expansion rate, i.e., with expansion rate, P≈1000s⁻¹. The numerical study supported by analytical and experimental research is presented in this work. The experimental study was carried out using an in-house experimental test rig, where nozzle was examined for different inlet air relative humidity values included in the range of 25 to 51%. The nozzle was tested for a supersonic flow as well as for flow with shock waves induced by elevated back pressure. The Schlieren photography technique and measurement of static pressure on the nozzle wall were used for qualitative identification of both condensation and shock waves. A numerical model validated against experimental data available in the literature was used for analysis of occurring flow phenomena. The analysis of the suspended particles number, diameter, and character (solid or liquid) revealed their connection with heterogeneous condensation importance. If the expansion of fluid without suspended particlesis considered, the condensation triggers so called condensation wave that appears downstream the nozzle throat. If the solid particles are considered, with increasing number of them, the condensation triggers upwind the nozzle throat, decreasing the condensation wave strength. Due to the release of latent heat during condensation, the fluid temperature and pressure increase, leading to the shift of normal shock upstream the flow. Owing relatively large diameters of the droplets created during heterogeneous condensation, they evaporate partially on the shock and continues to evaporate downstream the nozzle. If the liquid water particles are considered, due to their larger radius, their do not affect the expanding flow significantly, however might be in major importance while considering the compression phenomena as they will tend to evaporate on the shock wave. This research proves the need of further study of phase change phenomena in supersonic flow especially considering the interaction of droplets with the aerodynamic waves in the flow.

Keywords: aerodynamics, computational fluid dynamics, condensation, moist air, multi-phase flows

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Authors: Mohammad Shariq, Davinder Kaur

Abstract:

A series of multiferroic (BiFeO3)1−x(PbTiO3)x [x= 0, 0.1, 0.2, 0.3, 0.4 and 0.5] solid solution ceramics were synthesised by conventional solid-state reaction method. Well crystalline phase has been optimized at sintering temperature of 950°C for 2 hours. X rays diffraction studies of these ceramics revealed the existence of a morphotropic phase boundary (MPB) region in this system, which exhibits co-existence of rhombohedral and tetragonal phase with a large tetragonality (c/a ratio) in the tetragonal phase region. The average grain size of samples was found to be between 1-1.5 µm. The M-H curve revealed the BiFeO3 (BFO) as antiferromanetic material whereas, induced weak ferromagnetism was observed for (BiFeO3)1−x(PbTiO3)x composites with x=0.1, 0.2, 0.3, 0.4 and 0.5 at temperature of 5 K. The results evidenced the destruction of a space-modulated spin structure in bulk materials, via substituent effects, releasing a latent magnetization locked within the cycloid. Relative to unmodified BiFeO3, modified BiFeO3-PbTiO3 -based ceramics revealed enhancement in the electric-field-induced polarization.

Keywords: BiFeO3)1−x(PbTiO3)x ceramic, multiferroic, SQUID, magnetic properties

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Authors: Liaquat Ahmad, Muhammad Aslam, Muhammad Azam

Abstract:

In this article, we propose a control chart based on repetitive group sampling scheme for the location parameter. This charting scheme is based on the regression estimator; an estimator that capitalize the relationship between the variables of interest to provide more sensitive control than the commonly used individual variables. The control limit coefficients have been estimated for different sample sizes for less and highly correlated variables. The monitoring of the production process is constructed by adopting the procedure of the Shewhart’s x-bar control chart. Its performance is verified by the average run length calculations when the shift occurs in the average value of the estimator. It has been observed that the less correlated variables have rapid false alarm rate.

Keywords: average run length, control charts, process shift, regression estimators, repetitive group sampling

Procedia PDF Downloads 554

Authors: Sasitharan Ambicapathy, J. Vignesh, P. Sivaraj, Godfrey Derek Sams, K. Sabarinath, V. R. Sanal Kumar

Abstract:

The external flow simulation of a flying car at take off phase is a daunting task owing to the fact that the prediction of the transient unsteady flow features during its deployment phase is very complex. In this paper 3D numerical simulations of external flow of Ferrari F430 proposed flying car with different NACA 9618 rectangular wings have been carried. Additionally, the aerodynamics characteristics have been generated for optimizing its geometry for achieving the minimum take off velocity with better overall performance in both road and air. The three-dimensional standard k-omega turbulence model has been used for capturing the intrinsic flow physics during the take off phase. In the numerical study, a fully implicit finite volume scheme of the compressible, Reynolds-Averaged, Navier-Stokes equations is employed. Through the detailed parametric analytical studies we have conjectured that Ferrari F430 flying car facilitated with high wings having three different deployment histories during the take off phase is the best choice for accomplishing its better performance for the commercial applications.

Keywords: aerodynamics of flying car, air taxi, negative lift, roadable airplane

Procedia PDF Downloads 416