Search results for: transient cavity

Authors: Benalia Nadia, Zerzouri Nora, Ben Si Ali Nadia

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Abstract: Among the many different modern heuristic optimization methods, genetic algorithms (GA) and the particle swarm optimization (PSO) technique have been attracting a lot of interest. The GA has gained popularity in academia and business mostly because to its simplicity, ability to solve highly nonlinear mixed integer optimization problems that are typical of complex engineering systems, and intuitiveness. The mechanics of the PSO methodology, a relatively recent heuristic search tool, are modeled after the swarming or cooperative behavior of biological groups. It is suitable to compare the performance of the two techniques since they both aim to solve a particular objective function but make use of distinct computing methods. In this article, PSO and GA optimization approaches are used for the parameter tuning of the power system stabilizer and Proportional integral derivative regulator. Load angle and rotor speed variations in the single machine infinite bus bar system is used to measure the performance of the suggested solution.

Keywords: SMIB, genetic algorithm, PSO, transient stability, power system stabilizer, PID

Procedia PDF Downloads 83

Authors: Hazel James P. Agngarayngay, Arnold R. Elepaño

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Mango is the third most important export fruit in the Philippines. Despite the expanding mango trade in world market, problems on postharvest losses caused by pests and diseases are still prevalent. Many disease control and pest disinfestation methods have been studied and adopted. Heat treatment is necessary to eliminate pests and diseases to be able to pass the quarantine requirements of importing countries. During heat treatments, temperature and time are critical because fruits can easily be damaged by over-exposure to heat. Modeling the process enables researchers and engineers to study the behaviour of temperature distribution within the fruit over time. Understanding physical processes through modeling and simulation also saves time and resources because of reduced experimentation. This research aimed to simulate the heat transfer mechanism and predict the temperature distribution in ‘Carabao' mangoes during hot water treatment (HWT) and extended hot water treatment (EHWT). The simulation was performed in ANSYS CFD Software, using ANSYS CFX Solver. The simulation process involved model creation, mesh generation, defining the physics of the model, solving the problem, and visualizing the results. Boundary conditions consisted of the convective heat transfer coefficient and a constant free stream temperature. The three-dimensional energy equation for transient conditions was numerically solved to obtain heat flux and transient temperature values. The solver utilized finite volume method of discretization. To validate the simulation, actual data were obtained through experiment. The goodness of fit was evaluated using mean temperature difference (MTD). Also, t-test was used to detect significant differences between the data sets. Results showed that the simulations were able to estimate temperatures accurately with MTD of 0.50 and 0.69 °C for the HWT and EHWT, respectively. This indicates good agreement between the simulated and actual temperature values. The data included in the analysis were taken at different locations of probe punctures within the fruit. Moreover, t-tests showed no significant differences between the two data sets. Maximum heat fluxes obtained at the beginning of the treatments were 394.15 and 262.77 J.s-1 for HWT and EHWT, respectively. These values decreased abruptly at the first 10 seconds and gradual decrease was observed thereafter. Data on heat flux is necessary in the design of heaters. If underestimated, the heating component of a certain machine will not be able to provide enough heat required by certain operations. Otherwise, over-estimation will result in wasting of energy and resources. This study demonstrated that the simulation was able to estimate temperatures accurately. Thus, it can be used to evaluate the influence of various treatment conditions on the temperature-time history in mangoes. When combined with information on insect mortality and quality degradation kinetics, it could predict the efficacy of a particular treatment and guide appropriate selection of treatment conditions. The effect of various parameters on heat transfer rates, such as the boundary and initial conditions as well as the thermal properties of the material, can be systematically studied without performing experiments. Furthermore, the use of ANSYS software in modeling and simulation can be explored in modeling various systems and processes.

Keywords: heat transfer, heat treatment, mango, modeling and simulation

Procedia PDF Downloads 247

Authors: Hamed Djalal

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The aim of this paper is to perform a thermal-hydraulic analysis of the IAEA 10 MW benchmark reactor solving analytically and numerically, by mean of the finite volume method, respectively the steady state and transient forced convection in rectangular narrow channel between two parallel MTR-type fuel plates, imposed under a cosine shape heat flux. A comparison between both solutions is presented to determine the minimal coolant velocity which can ensure a safe reactor core cooling, where the cladding temperature should not reach a specific safety limit 90 °C. For this purpose, a computer program is developed to determine the principal parameter related to the nuclear core safety, such as the temperature distribution in the fuel plate and in the coolant (light water) as a function of the inlet coolant velocity. Finally, a good agreement is noticed between the both analytical and numerical solutions, where the obtained results are displayed graphically.

Keywords: forced convection, pressure drop, thermal hydraulic analysis, vertical heated rectangular channel

Procedia PDF Downloads 154

Authors: Santhosh A. K.

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This work presents an efficient monolithic finite element strategy for solving thermo-fluid-structure interaction problems involving compressible fluids and linear-elastic structure. This formulation uses displacement variables for structure and velocity variables for the fluid, with no additional variables required to ensure traction, velocity, temperature, and heat flux continuity at the fluid-structure interface. Rate of convergence in each time step is quadratic, which is achieved in this formulation by deriving an exact tangent stiffness matrix. The robustness and good performance of the method is ascertained by applying the proposed strategy on a wide spectrum of problems taken from the literature pertaining to steady, transient, two dimensional, axisymmetric, and three dimensional fluid flow and conjugate heat transfer. It is shown that the current formulation gives excellent results on all the case studies conducted, which includes problems involving compressibility effects as well as problems where fluid can be treated as incompressible.

Keywords: linear thermoelasticity, compressible flow, conjugate heat transfer, monolithic FEM

Procedia PDF Downloads 199

Authors: Khaled M. EL-Naggar

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Synchronizing and damping torque coefficients of a synchronous machine can give a quite clear picture for machine behavior during transients. These coefficients are used as a power system transient stability measurement. In this paper, a crow search optimization algorithm is presented and implemented to study the power system stability during transients. The algorithm makes use of the machine responses to perform the stability study in time domain. The problem is formulated as a dynamic estimation problem. An objective function that minimizes the error square in the estimated coefficients is designed. The method is tested using practical system with different study cases. Results are reported and a thorough discussion is presented. The study illustrates that the proposed method can estimate the stability coefficients for the critical stable cases where other methods may fail. The tests proved that the proposed tool is an accurate and reliable tool for estimating the machine coefficients for assessment of power system stability.

Keywords: optimization, estimation, synchronous, machine, crow search

Procedia PDF Downloads 140

Authors: Fuad H. Veliev

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Negative pressure phenomenon appears in many thermodynamic, geophysical and biophysical processes in the Nature and technological systems. For more than 100 years of the laboratory researches beginning from F. M. Donny’s tests, the great values of negative pressure have been achieved. But this phenomenon has not been practically applied, being only a nice lab toy due to the special demands for the purity and homogeneity of the liquids for its appearance. The possibility of creation of direct wave of negative pressure in real heterogeneous liquid systems was confirmed experimentally under the certain kinetic and hydraulic conditions. The negative pressure can be considered as the factor of both useful and destroying energies. The new approach to generation of the negative pressure waves in impure, unclean fluids has allowed the creation of principally new energy saving technologies and installations to increase the effectiveness and efficiency of different production processes. It was proved that the negative pressure is one of the main factors causing hard troubles in some technological and natural processes. Received results emphasize the necessity to take into account the role of the negative pressure as an energy factor in evaluation of many transient thermohydrodynamic processes in the Nature and production systems.

Keywords: liquid systems, negative pressure, temperature, wave, metastable state

Procedia PDF Downloads 416

Authors: S. Alireza Mirghasemi, Elly Trepman, Mohammad Saleh Sadeghi, Narges Rahimi Gabaran, Shervin Rashidinia

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Bone marrow edema syndrome (BMES) is an uncommon and self-limited syndrome characterized by atraumatic extremity pain with unknown of etiology. Symptom onset may include sudden or gradual swelling and pain at rest or during activity, usually at night. This syndrome mostly affects middle-aged men and younger women who have pain in the lower extremities. The most common sites involved with BMES, in decreasing order of frequency, are the bones about the hip, knee, ankle, and foot. The diagnosis of BMES is made with magnetic resonance imaging to exclude other causes of bone marrow edema. The correct diagnosis often is delayed because of the low prevalence and nonspecific signs in the foot and ankle. This delay may intensify bone pain and impair patient function and quality of life. The goal of BMES treatment is to relieve pain and shorten disease duration. Treatment options are limited and may include symptomatic treatment, pharmacologic treatment, and surgery.

Keywords: transient osteoporosis, bone marrow edema syndrome, iloprost, bisphosphonates

Procedia PDF Downloads 363

Authors: Shin Je Lee, Go Bong Choi, Jeong Cheol Seo, Jong Min Lee, Gibaek Lee

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Water pipe network is installed underground and once equipped; it is difficult to recognize the state of pipes when the leak or burst happens. Accordingly, post management is often delayed after the fault occurs. Therefore, the systematic fault management system of water pipe network is required to prevent the accident and minimize the loss. In this work, we develop online fault detection system of water pipe network using data of pipes such as flow rate or pressure. The transient model describing water flow in pipelines is presented and simulated using Matlab. The fault situations such as the leak or burst can be also simulated and flow rate or pressure data when the fault happens are collected. Faults are detected using statistical methods of fast Fourier transform and discrete wavelet transform, and they are compared to find which method shows the better fault detection performance.

Keywords: fault detection, water pipeline model, fast Fourier transform, discrete wavelet transform

Procedia PDF Downloads 512

Authors: Chen Niu, Xuesong Zhang, Dejiang Shang, Yongwei Liu

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Fishes can secrete high molecular weight fluid on their body skin to enable their rapid movement in the water. In this work, we employ a hybrid method that combines Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) to investigate the effects of different mucus viscosities and injection velocities on fluctuation pressure in the boundary layer and flow-induced structural vibration noise of a flat plate model. To accurately capture the transient flow distribution on the plate surface, we use Large Eddy Simulation (LES) while the mucus inlet is positioned at a sufficient distance from the model to ensure effective coverage. Mucus injection is modeled using the Volume of Fluid (VOF) method for multiphase flow calculations. The results demonstrate that mucus control of pulsating pressure effectively reduces flow-induced structural vibration noise, providing an approach for controlling flow-induced noise in underwater vehicles.

Keywords: mucus, flow control, noise control, flow-induced noise

Procedia PDF Downloads 145

Authors: P. Kamphikul, P. Krachodnok, R. Wongsan

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This paper presents the gain improvement of a sector antenna for mobile phone base station by using the new technique to enhance its gain for microstrip antenna (MSA) array without construction enlargement. The curved woodpile Electromagnetic Band Gap (EBG) has been utilized to improve the gain instead. The advantages of this proposed antenna are reducing the length of MSAs array but providing the higher gain and easy fabrication and installation. Moreover, it provides a fan-shaped radiation pattern, wide in the horizontal direction and relatively narrow in the vertical direction, which appropriate for mobile phone base station. The paper also presents the design procedures of a 1x8 MSAs array associated with U-shaped reflector for decreasing their back and side lobes. The fabricated curved woodpile EBG exhibits bandgap characteristics at 2.1 GHz and is utilized for realizing a resonant cavity of MSAs array. This idea has been verified by both the Computer Simulation Technology (CST) software and experimental results. As the results, the fabricated proposed antenna achieves a high gain of 20.3 dB and the half-power beam widths in the E- and H-plane of 36.8 and 8.7 degrees, respectively. Good qualitative agreement between measured and simulated results of the proposed antenna was obtained.

Keywords: gain improvement, microstrip antenna array, electromagnetic band gap, base station

Procedia PDF Downloads 311

Authors: Farzad Razavi, Behrooz Taheri, Mohammad Parpaei, Mehdi Mohammadi Ghalesefidi, Siamak Zarei

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As one of the major problems in protecting large-dimension power systems, power swing and its effect on distance have caused a lot of damages to energy transfer systems in many parts of the world. Therefore, power swing has gained attentions of many researchers, which has led to invention of different methods for power swing detection. Power swing detection algorithm is highly important in distance relay, but protection relays should have general requirements such as correct fault detection, response rate, and minimization of disturbances in a power system. To ensure meeting the requirements, protection relays need different tests during development, setup, maintenance, configuration, and troubleshooting steps. This paper covers power swing scheme of the modern numerical relay protection, 7sa522 to address the effect of the different fault types on the function of the power swing blocking. In this study, it was shown that the different fault types during power swing cause different time for unblocking distance relay.

Keywords: power swing, distance relay, power system protection, relay test, transient in power system

Procedia PDF Downloads 385

Authors: Aref Maalej, Marwa Fakhfakh, Wael Ben Amira

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We present in this work a numerical investigation of fluid-structure interaction to study the elastic behavior of flexible rotors. The principal aim is to provide the effect of the aero/hydrodynamic parameters on the bending deformation of flexible rotors. This study is accomplished using the strong two-way fluid-structure interaction (FSI) developed by the ANSYS Workbench software. This method is used for coupling the fluid solver to the transient structural solver to study the elastic behavior of flexible rotors in water. In this study, we use a moderately flexible rotor modeled by a single blade with simplified rectangular geometry. In this work, we focus on the effect of the rotational frequency on the flapwise bending deformation. It is demonstrated that the blade deforms in the downstream direction, and the amplitude of these deformations increases with the rotational frequencies. Also, from a critical frequency, the blade begins to deform in the upstream direction.

Keywords: numerical simulation, flexible blade, fluid-structure interaction, ANSYS workbench, flapwise deformation

Procedia PDF Downloads 87

Authors: Shaoying Guo, Yanyun Xu, Meng Zhang, Weiqing Huang

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The wireless communication network is developing rapidly, thus the wireless security becomes more and more important. Specific emitter identification (SEI) is an vital part of wireless communication security as a technique to identify the unique transmitters. In this paper, a SEI method based on multiscale dispersion entropy (MDE) and refined composite multiscale dispersion entropy (RCMDE) is proposed. The algorithms of MDE and RCMDE are used to extract features for identification of five wireless devices and cross-validation support vector machine (CV-SVM) is used as the classifier. The experimental results show that the total identification accuracy is 99.3%, even at low signal-to-noise ratio(SNR) of 5dB, which proves that MDE and RCMDE can describe the communication signal series well. In addition, compared with other methods, the proposed method is effective and provides better accuracy and stability for SEI.

Keywords: cross-validation support vector machine, refined com- posite multiscale dispersion entropy, specific emitter identification, transient signal, wireless communication device

Procedia PDF Downloads 129

Authors: Lukas Kano Mangalla, Raden Rinova Sisworo, Luther Pagiling

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Torrefaction is an emerging thermo-chemical treatment process that aims to improve the quality of biomass fuels. This study focused on upgrading the waste teakwood through microwave torrefaction processes and investigating the key operating parameters to improve energy density for the quality of biochar production. The experiments were carried out in a 250 mL reactor placed in a microwave cavity on two different media, inert and non-inert. The microwave was operated at a frequency of 2.45GHz with power level variations of 540W, 720W, and 900W, respectively. During torrefaction processes, the nitrogen gas flows into the reactor at a rate of 0.125 mL/min, and the air flows naturally. The temperature inside the reactor was observed every 0.5 minutes for 20 minutes using a K-Type thermocouple. Changes in the mass and the properties of the torrefied products were analyzed to predict the correlation between calorific value, mass yield, and level power of the microwave. The results showed that with the increase in the operating power of microwave torrefaction, the calorific value and energy density of the product increased significantly, while mass and energy yield tended to decrease. Air can be a great potential media for substituting the expensive nitrogen to perform the microwave torrefaction for teakwood biomass.

Keywords: torrefaction, microwave heating, energy enhancement, mass and energy yield

Procedia PDF Downloads 92

Authors: Roselyn Zaman, Mobarak Hossain

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A new mathematical model is developed to study crack breathing behavior considering effect of angular position of unbalanced force at different crack locations. Crack breathing behavior has been determined using effectual bending angle by studying the transient change of the crack area. Different crack breathing behavior of the unbalanced shaft has been observed for different combination of angular position of unbalanced force with crack location except crack locations 0.3L and 0.8335L, where L is the total length of the shaft, where unbalanced shaft behave completely like the balanced shaft. Based on different combination of angular position of unbalanced force with crack location, the stiffness of unbalanced shaft can be divided into three regions. An unbalanced shaft is overall stiffer than a balanced shaft when angular position of unbalance force is between 90° to 270° and crack located between 0.3L and 0.8335L, and it is overall flexible when the crack located in outside this crack region. On the other hand, it is overall flexible when angular position of unbalanced force is between 0° to 90° or 270° to 360° and crack located in middle region and it is overall stiffer for outside this crack region.

Keywords: cracked shaft, crack location, shaft stiffness, unbalanced force, and unbalanced force orientation

Procedia PDF Downloads 268

Authors: Manasi Roy, Raju Mondal

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During last two decades the synthesis and design of MOFs or novel coordination polymers (CPs) has flourished as an emerging area of research due to their role as functional materials. Accordingly, ten new cobalt-based MOFs have been synthesized using a simple bispyrazole ligand, 4,4′-methylene-bispyrazole (H2MBP), and isophthalic acid (H2IPA) and its four 5-substituted derivatives R-H2IPA (R = COOH, OH, tBu, NH2). The major aim of this study was to validate the mutual influence of temperature and substitutions on the final structural self-assembly. Five different isophthalic acid derivatives were used to study the influence of substituents while each reaction was carried out at two different temperatures to assess the temperature effect. A clear correlation was observed between the reaction temperature and the coordination number of the cobalt atoms which consequently changes the self assembly pattern. Another fact that the periodical change in coordination number did bring about some systematic changes in the structural network via secondary building unit selectivity. With the presence of a tunable cavity inside the network, and unsaturated metal centers, MOFs show highly encouraging photocatalytic degradation of toxic dye with a potential application in waste water purification. Another fascinating aspect of this work is the construction of magnetic coordination polymers with the occurrence of a not-so-common MCE behavior of cobalt-based MOF.

Keywords: MOFs, temperature effect, MCE, dye degradation

Procedia PDF Downloads 136

Authors: Ahmed Shariful Alam, Abu Hena M. Mustafa Kamal, M. Abdul Rahman, M. Nasmus Sakib Khan Shabbir, Atiqul Islam

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According to the rules of quantum mechanics there is a non-vanishing probability of for an electron to tunnel through a thin insulating barrier or a thin capacitor which is not possible according to the laws of classical physics. Tunneling of electron through a thin insulating barrier or tunnel junction is a random event and the magnitude of current flowing due to the tunneling of electron is very low. As the current flowing through a Single Electron Transistor (SET) is the result of electron tunneling through tunnel junctions of its source and drain the supply voltage requirement is also very low. As a result, the power consumption across a Single Electron Transistor is ultra-low in comparison to that of a MOSFET. In this paper simulations have been done with PSPICE for an inverter built with both SETs and MOSFETs. 35mV supply voltage was used for a SET built inverter circuit and the supply voltage used for a CMOS inverter was 3.5V.

Keywords: ITRS, enhancement type MOSFET, island, DC analysis, transient analysis, power consumption, background charge co-tunneling

Procedia PDF Downloads 526

Authors: Mark Schudeleit, Christian Sieg, Ferit Küçükay

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This paper describes how to dimension the electric components of a 48V hybrid system considering real customer use. Furthermore, it provides information about savings in energy and CO2 emissions by a customer-tailored 48V hybrid. Based on measured customer profiles, the electric units such as the electric motor and the energy storage are dimensioned. Furthermore, the CO2 reduction potential in real customer use is determined compared to conventional vehicles. Finally, investigations are carried out to specify the topology design and preliminary considerations in order to hybridize a conventional vehicle with a 48V hybrid system. The emission model results from an empiric approach also taking into account the effects of engine dynamics on emissions. We analyzed transient engine emissions during representative customer driving profiles and created emission meta models. The investigation showed a significant difference in emissions when simulating realistic customer driving profiles using the created verified meta models compared to static approaches which are commonly used for vehicle simulation.

Keywords: customer use, dimensioning, hybrid electric vehicles, vehicle simulation, 48V hybrid system

Procedia PDF Downloads 508

Authors: Maged Assem Soliman Mossallam

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The conversion of solar thruster model to an upper stage hydrogen rocket is considered. Solar thruster categorization limits its capabilities to low and moderate thrust system with high specific impulse. The current study proposes a different concept for such systems by increasing the thrust which enables using as an upper stage rocket and for future launching purposes. A computational model for the thruster is discussed for solar thruster subsystems. The first module depends on ray tracing technique to determine the intercepted solar power by the hydrogen combustion chamber. The cavity receiver is modeled using finite volume technique. The final module imports the heated hydrogen properties to the nozzle using quasi one dimensional simulation. The probability of shock waves formulation inside the nozzle is almost diminished as the outlet pressure in space environment tends to zero. The computational model relates the high thrust hydrogen rocket conversion to the design parameters and operating conditions of the thruster. Three different designs for solar thruster systems are discussed. The first design is a low thrust high specific impulse design that produces about 10 Newton of thrust .The second one output thrust is about 250 Newton and the third design produces about 1000 Newton.

Keywords: space propulsion, hydrogen rocket, thrust, specific impulse

Procedia PDF Downloads 166

Authors: Haidy N. Salem, Nada O. Kamel, Shahinaz N. Hassan, Sherif M. Elhefnawy

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Aim: to assess the effect of using turmeric powder extract on changes of tooth color with extra-coronal and intra-coronal bleaching methods. Methods: Turmeric powder extract was weighted and mixed with two different hydrogen peroxide concentrations (3% and 6%) to be used as a bleaching agent. Thirty teeth were allocated into three groups (n=10): Group A: Bleaching agent (6%) was applied on the labial surface, Group B: Bleaching agent (3%) was applied inside the pulp chamber and Group C: Extra and intra-coronal bleaching techniques were used (6% and 3% respectively). A standardized access cavity was opened in the palatal surface of each tooth in both Groups B and C. Color parameters were measured using a spectrophotometer. Results: A statistically significant difference in color difference values (∆E*) and enamel brightness (∆L*) was found between Group C and each of Groups A and B. There was no statistically significant difference in (∆E*) and (∆L*) between Group A and Group B. The highest mean value of (∆E*) and (∆L*) was found in Group C, while the least mean value was found in Group B. Conclusion: Bleaching the external and internal tooth structure with low concentrations of hydrogen peroxide solution mixed with turmeric extract has a promising effect in color enhancement.

Keywords: bleaching, hydrogen peroxide, spectrophotometer, turmeric

Procedia PDF Downloads 119

Authors: Sung-Min Kim, Joon-Hong Park, Hyuk Choi

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This study is focused on the comparative analysis and improvement to grasp the flow characteristic of the anti-splash device located under the P/V valve and new concept design models using the CFD. The P/V valve located upper deck to solve the pressure rising and vacuum condition of inner tank of the liquid cargo ships occurred oil outflow accident by transverse and longitudinal sloshing force. Anti-splash device is fitted to improve and prevent this problem in the shipbuilding industry, but the oil outflow accidents are still reported by ship owners. Thus, 4 types of new design model are presented by this study, and then comparative analysis is conducted with new models and existing model. Mostly the key criterion of this problem is flux in the outlet of the anti-splash device. Therefore, the flow and velocity are grasped by transient analysis, and then it decided optimum model and design parameters to develop model. Later, it is needed to develop an anti-splash device by flow test to get certification and verification using experiment equipments.

Keywords: anti-splash device, P/V valve, sloshing, CFD

Procedia PDF Downloads 634

Authors: Ahmed A. Al-Harbi

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This paper presents a comparative study of effects of the repeated solid obstacles on the propagation of H2-Air premixed flames. Pressure, speed of the flame front as well as structure of reaction zones are studied for hydrogen. Two equivalence ratios are examined for different configurations of three baffle plates and two obstacles with a square cross-section having blockage ratios of either 0.24 or 0.5. Hydrogen fuel mixtures with two equivalence ratios of 0.7 and 0.8 are studied and this is limited by the excessive overpressures. The results show that the peak pressure and its rate of change can be increased by increasing the blockage ratio or by decreasing the space between successive baffles. As illustrated by the high speed images of LIF-OH, the degree of wrinkling and contortion in the flame front increase as the blockages increase. The images also show how the flame front relaminarises with increasing distances between obstacles, which accounts for the pressure decrease with increasing separation. It is also found that more than one obstacle is needed to achieve a turbulent flame structure with intense corrugations.

Keywords: premixed propagating flames, flame-obstacle interaction, turbulent premixed flames, overpressure, transient flames

Procedia PDF Downloads 377

Authors: Maged Assem Soliman Mossallam

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Microsatellites' low available power limits the usage of active thermal control techniques in these categories of satellites. Passive thermal control techniques are preferred due to their high reliability and power saving which increase the satellite's survivability in orbit. Steady-state and transient simulations are applied to the microsatellite design in order to define severe conditions in orbit. Satellite thermal orbital three-dimensional simulation is performed using thermal orbit propagator coupled with Comsol Multiphysics finite element solver. Sensitivity study shows the dependence of the satellite temperatures on the internal heat dissipation and the thermooptical properties of anodization coatings. The critical case is defined as low power orbiting mode at the eclipse zone. Using black anodized aluminum drops the internal temperatures to severe values which exceed the permissible cold limits. Replacement with anodized titanium returns the internal subsystems' temperatures back to adequate temperature fluctuations limits.

Keywords: passive thermal control, thermooptical, anodized titanium, emissivity, absorbtiviy

Procedia PDF Downloads 142

Authors: Nevila Alliu, Saimir Heta, Ilma Robo, Vera Ostreni

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Periodontitis as an oral pathology caused by specific bacterial flora functions as a focal infection for the onset and aggravation of arteriosclerosis. These two distant pathologies, since they affect organs at a distance from each other, communicate with each other with correlation at the level of markers of inflammation in the blood. Fluctuations in the level of fibrinogen in the blood, depending on the active or passive phase of the existing periodontitis, affect the promotion of arteriosclerosis. The study is of the review type to analyze the effect of non-surgical periodontal treatment on fluctuations in the level of fibrinogen in the blood. The reduction of fibrinogen levels in the blood after non-surgical periodontal treatment of periodontitis in the patient's cavity is visible data and supported by literature sources. Also, the influence of a high amount of fibrinogen in the blood on the occurrence of arteriosclerosis is also another important data that again relies on many sources of literature. Conclusions: Thromboembolism and arteriosclerosis, as risk factors expressed in clinical data, have temporary bacteremia in the blood, which can occur significantly and often between phases of non-surgical periodontal treatment of periodontitis, treatments performed with treatment phases and protocols of predetermined treatment. Arterial thromboembolism has a significant factor, such as high levels of fibrinogen in the blood, which are significantly reduced during the period of non-surgical periodontal treatment.

Keywords: fibrinogen, refractory periodontitis, atherosclerosis, non-surgical, periodontal treatment

Procedia PDF Downloads 108

Authors: T. Bensana, S. Mekhilef

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The methodology of vibration based condition monitoring technology has been developing at a rapid stage in the recent years suiting to the maintenance of sophisticated and complicated machines. The ability of wavelet analysis to efficiently detect non-stationary, non-periodic, transient features of the vibration signal makes it a demanding tool for condition monitoring. This paper presents a methodology for fault diagnosis of rolling element bearings based on wavelet envelope power spectrum technique is analysed in both the time and frequency domains. In the time domain the auto-correlation of the wavelet de-noised signal is applied to evaluate the period of the fault pulses. However, in the frequency domain the wavelet envelope power spectrum has been used to identify the fault frequencies with the single sided complex Laplace wavelet as the mother wavelet function. Results show the superiority of the proposed method and its effectiveness in extracting fault features from the raw vibration signal.

Keywords: preventive maintenance, fault diagnostics, rolling element bearings, wavelet de-noising

Procedia PDF Downloads 379

Authors: Wissem Tighidet, Faïçal Naït Bouda, Moussa Allouche

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The numerical study of the Fluid-Structure Interaction (FSI) in a partially filled flexible tank submitted to a horizontal harmonic excitation motion. It is investigated by using two-way Fluid-Structure Interaction (FSI) in a flexible tank by Coupling between the Transient Structural (Mechanical) and Fluid Flow (Fluent) in ANSYS-Workbench Student version. The Arbitrary Lagrangian-Eulerian (ALE) formulation is adopted to solve with the finite volume method, the Navier-Stokes equations in two phases in a moving domain. The Volume of Fluid (VOF) method is applied to track the free surface. However, the equations of the dynamics of the structure are solved with the finite element method assuming a linear elastic behavior. To conclude, the Fluid-Structure Interaction (IFS) has a vital role in the analysis of the dynamic behavior of the rectangular tank. The results indicate that the flexibility of the tank walls has a significant impact on the amplitude of tank sloshing and the deformation of the free surface as well as the effect of liquid sloshing on wall deformation.

Keywords: arbitrary lagrangian-eulerian, fluid-structure interaction, sloshing, volume of fluid

Procedia PDF Downloads 105

Authors: Aulina R. Rahmi, Farid Yuristiawan, Annisa Ibifadillah, Ummu H. Amri, Hidayati Gunawan

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Glass ionomer cement is one of the filling material that often used on the field of dentistry because it is relatively less expensive and mostly available. Restoration materials could undergo changes in their clinical properties such as changes in roughness of the restoration`s surface. An increase of surface roughness accelerates bacterial colonization and plaque maturation. In the oral cavity, GIC was exposed to various substances, such as toothpaste, an oral care product used during toothbrushing. One of the popular toothpaste is whitening toothpaste. Abrasive and chemical agents such as hydrogen peroxide in whitening toothpaste could increase the surface roughness of restorative materials. Objective: To determine the differences on the surface roughness of glass ionomer cement that was brushed with whitening and conventional toothpaste. Method: This study was done using experimental laboratory method with pre and post test design. There were 36 samples which were divided into 2 groups. The first group was brushed with whitening toothpaste and the second group was brushed with conventional toothpaste, each for 2 minutes. Surface roughness value of the specimens was measured by using Roughness Tester test. Result: The data was analyzed by using independent t-test and the result of this study showed there was a significant difference between the surface of glass ionomer cement which was brushed with whitening and conventional toothpaste (p=0,000). Conclusion: Glass ionomer cement that was brushed with whitening toothpaste produced more roughness than conventional toothpaste.

Keywords: glass ionomer cement, surface roughness, toothpaste, roughness tester

Procedia PDF Downloads 288

Authors: Oswaldo Otero, Eduardo A. Orozco, Ana M. Herrera

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In this work, we present results from analytical and numerical studies of the electron acceleration by a TE₀₁₁ cylindrical microwave mode in a static homogeneous magnetic field under electron cyclotron resonance (ECR) condition. The stability of the orbits is analyzed using the particle orbit theory. In order to get a better understanding of the interaction wave-particle, we decompose the azimuthally electric field component as the superposition of right and left-hand circular polarization standing waves. The trajectory, energy and phase-shift of the electron are found through a numerical solution of the relativistic Newton-Lorentz equation in a finite difference method by the Boris method. It is shown that an electron longitudinally injected with an energy of 7 keV in a radial position r=Rc/2, being Rc the cavity radius, is accelerated up to energy of 90 keV by an electric field strength of 14 kV/cm and frequency of 2.45 GHz. This energy can be used to produce X-ray for medical imaging. These results can be used as a starting point for study the acceleration of electrons in a magnetic field changing slowly in time (GYRAC), which has some important applications as the electron cyclotron resonance ion proton accelerator (ECR-IPAC) for cancer therapy and to control plasma bunches with relativistic electrons.

Keywords: Boris method, electron cyclotron resonance, finite difference method, particle orbit theory, X-ray

Procedia PDF Downloads 159

Authors: Ghazanfari Masoumeh, Hajimohammadi Bahador, Eskandari Soheyl, Karimian Khosroshahi Nader

Abstract:

Consumption of ready to cook meat products such as hamburgers, sausages and etc is being increased in the worldwide specially in the big cities , so safety and quality required for food products is very important and vital for consumers with consideration of meat price and increasing demands for meat products, possibility of substitution of cheep and unauthorized textures such as undesirable enclosures animals (massacre, lung tissue, breast of spleen, the organs abdominal cavity, gizzard chicken, skin, etc. ) have increased in the recent years, in this study 30 industrial and 30 handmade hamburgers in fast food restaurants detected out of Iranian national standard for hamburger No. 2304 in using the unauthorized textures. The purpose of this study was to determine using of chicken skin in produced hamburgers from chicken meat in Tehran base on histology methods. The rates of skin used were, 2 % in industrial and 9 % in handmade formula samples. Statistically using the unauthorized textures had significant higher rate in handmade (P < 0.05) in compare with the industrial samples. The results showed the handmade hamburgers with higher adulteration rate and non-compliance with the hamburger national standard could be a potentially health hazard.

Keywords: histology, adulteration, unauthorized textures, undesirable enclosures animals

Procedia PDF Downloads 455

Authors: Raza Abdulla Saeed

Abstract:

In this study, the three-dimensional cavitating turbulent flow in a complete Francis turbine is simulated using mixture model for cavity/liquid two-phase flows. Numerical analysis is carried out using ANSYS CFX software release 12, and standard k-ε turbulence model is adopted for this analysis. The computational fluid domain consist of spiral casing, stay vanes, guide vanes, runner and draft tube. The computational domain is discretized with a three-dimensional mesh system of unstructured tetrahedron mesh. The finite volume method (FVM) is used to solve the governing equations of the mixture model. Results of cavitation on the runner’s blades under three different boundary conditions are presented and discussed. From the numerical results it has been found that the numerical method was successfully applied to simulate the cavitating two-phase turbulent flow through a Francis turbine, and also cavitation is clearly predicted in the form of water vapor formation inside the turbine. By comparison the numerical prediction results with a real runner; it’s shown that the region of higher volume fraction obtained by simulation is consistent with the region of runner cavitation damage.

Keywords: computational fluid dynamics, hydraulic francis turbine, numerical simulation, two-phase mixture cavitation model

Procedia PDF Downloads 561