Search results for: Thermal characteristic
356 Detection of Near Failure Winding due to Deformation in 33/11kV Power Transformer by using Low Voltage Impulse (LVI) Test Method and Validated through Untanking
Authors: R. Samsudin, Yogendra, Hairil Satar, Y.Zaidey
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Power transformer consists of components which are under consistent thermal and electrical stresses. The major component which degrades under these stresses is the paper insulation of the power transformer. At site, lightning impulses and cable faults may cause the winding deformation. In addition, the winding may deform due to impact during transportation. A deformed winding will excite more stress to its insulating paper thus will degrade it. Insulation degradation will shorten the life-span of the transformer. Currently there are two methods of detecting the winding deformation which are Sweep Frequency Response Analysis (SFRA) and Low Voltage Impulse Test (LVI). The latter injects current pulses to the winding and capture the admittance plot. In this paper, a transformer which experienced overheating and arcing was identified, and both SFRA and LVI were performed. Next, the transformer was brought to the factory for untanking. The untanking results revealed that the LVI is more accurate than the SFRA method for this case study.Keywords: Winding Deformation, Arcing, Dissolved GasAnalysis, Sweep Frequency Response Analysis, Low VoltageImpulse Method
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2831355 Firing Angle Range Control For Minimising Harmonics in TCR Employed in SVC-s
Authors: D. R. Patil, U. Gudaru
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Most electrical distribution systems are incurring large losses as the loads are wide spread, inadequate reactive power compensation facilities and their improper control. A typical static VAR compensator consists of capacitor bank in binary sequential steps operated in conjunction with a thyristor controlled reactor of the smallest step size. This SVC facilitates stepless control of reactive power closely matching with load requirements so as to maintain power factor nearer to unity. This type of SVC-s requiring a appropriately controlled TCR. This paper deals with an air cored reactor suitable for distribution transformer of 3phase, 50Hz, Dy11, 11KV/433V, 125 KVA capacity. Air cored reactors are designed, built, tested and operated in conjunction with capacitor bank in five binary sequential steps. It is established how the delta connected TCR minimizes the harmonic components and the operating range for various electrical quantities as a function of firing angle is investigated. In particular firing angle v/s line & phase currents, D.C. components, THD-s, active and reactive powers, odd and even triplen harmonics, dominant characteristic harmonics are all investigated and range of firing angle is fixed for satisfactory operation. The harmonic spectra for phase and line quantities at specified firing angles are given. In case the TCR is operated within the bound specified in this paper established through simulation studies are yielding the best possible operating condition particularly free from all dominant harmonics.Keywords: Binary Sequential switched capacitor bank, TCR, Nontriplen harmonics, step less Q control, Active and Reactivepower, Simulink
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 5979354 Study on the Variation Effects of Diverging Angleon Characteristics of Flow in Converging and Diverging Ducts by Numerical Method
Authors: Moghiman Mohammad, Amiri Maryam, Amiri Amirhosein
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The present paper develops and validates a numerical procedure for the calculation of turbulent combustive flow in converging and diverging ducts and throuh simulation of the heat transfer processes, the amount of production and spread of Nox pollutant has been measured. A marching integration solution procedure employing the TDMA is used to solve the discretized equations. The turbulence model is the Prandtl Mixing Length method. Modeling the combustion process is done by the use of Arrhenius and Eddy Dissipation method. Thermal mechanism has been utilized for modeling the process of forming the nitrogen oxides. Finite difference method and Genmix numerical code are used for numerical solution of equations. Our results indicate the important influence of the limiting diverging angle of diffuser on the coefficient of recovering of pressure. Moreover, due to the intense dependence of Nox pollutant to the maximum temperature in the domain with this feature, the Nox pollutant amount is also in maximum level.
Keywords: Converging and Diverging Duct, Combustion, Diffuser, Diverging Angle, Nox
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1527353 Influence of Paralleled Capacitance Effect in Well-defined Multiple Value Logical Level System with Active Load
Authors: Chih Chin Yang, Yen Chun Lin, Hsiao Hsuan Cheng
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Three similar negative differential resistance (NDR) profiles with both high peak to valley current density ratio (PVCDR) value and high peak current density (PCD) value in unity resonant tunneling electronic circuit (RTEC) element is developed in this paper. The PCD values and valley current density (VCD) values of the three NDR curves are all about 3.5 A and 0.8 A, respectively. All PV values of NDR curves are 0.40 V, 0.82 V, and 1.35 V, respectively. The VV values are 0.61 V, 1.07 V, and 1.69 V, respectively. All PVCDR values reach about 4.4 in three NDR curves. The PCD value of 3.5 A in triple PVCDR RTEC element is better than other resonant tunneling devices (RTD) elements. The high PVCDR value is concluded the lower VCD value about 0.8 A. The low VCD value is achieved by suitable selection of resistors in triple PVCDR RTEC element. The low PV value less than 1.35 V possesses low power dispersion in triple PVCDR RTEC element. The designed multiple value logical level (MVLL) system using triple PVCDR RTEC element provides equidistant logical level. The logical levels of MVLL system are about 0.2 V, 0.8 V, 1.5 V, and 2.2 V from low voltage to high voltage and then 2.2 V, 1.3 V, 0.8 V, and 0.2 V from high voltage back to low voltage in half cycle of sinusoid wave. The output level of four levels MVLL system is represented in 0.3 V, 1.1 V, 1.7 V, and 2.6 V, which satisfies the NMP condition of traditional two-bit system. The remarkable logical characteristic of improved MVLL system with paralleled capacitor are with four significant stable logical levels about 220 mV, 223 mV, 228 mV, and 230 mV. The stability and articulation of logical levels of improved MVLL system are outstanding. The average holding time of improved MVLL system is approximately 0.14 μs. The holding time of improved MVLL system is fourfold than of basic MVLL system. The function of additional capacitor in the improved MVLL system is successfully discovered.Keywords: Capacitance, Logical level, Constant current source
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1378352 Characterization of Biodegradable Nanocomposites with Poly (Lactic Acid) and Multi-Walled Carbon Nanotubes
Authors: Md F. Mina, Mohammad D.H. Beg, Muhammad R. Islam, Abu K. M. M. Alam A. Nizam, Rosli M. Younus
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In this study, structural, mechanical, thermal and electrical properties of poly (lactic acid) (PLA) nanocomposites with low-loaded (0-1.5 wt%) untreated, heat and nitric acid treated multiwalled carbon nanotubes (MWCNTs) were studied. Among the composites, untreated 0.5 wt % MWCNTs and acid-treated 1.0 wt% MWCNTs reinforced PLA show the tensile strength and modulus values higher than the others. These two samples along with pure PLA exhibit the stable orthorhombic α-form, whilst other samples reveal the less stable orthorhombic β-form, as demonstrated by X-ray diffraction study. Differential scanning calorimetry reveals the evolution of the mentioned different phases by controlled cooling and discloses an enhancement of PLA crystallization by nanotubes incorporation. Thermogravimetric analysis shows that the MWCNTs loaded sample degraded faster than PLA. Surface resistivity of the nanocomposites is found to be dropped drastically by a factor of 1013 with a low loading of MWCNTs (1.5 wt%).Keywords: Crystallization, multi-walled carbon nanotubes, nanocomposites, Poly (lactic acid).
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2594351 Thermalytix: An Advanced Artificial Intelligence Based Solution for Non-Contact Breast Screening
Authors: S. Sudhakar, Geetha Manjunath, Siva Teja Kakileti, Himanshu Madhu
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Diagnosis of breast cancer at early stages has seen better clinical and survival outcomes. Survival rates in developing countries like India are very low due to accessibility and affordability issues of screening tests such as Mammography. In addition, Mammography is not much effective in younger women with dense breasts. This leaves a gap in current screening methods. Thermalytix is a new technique for detecting breast abnormality in a non-contact, non-invasive way. It is an AI-enabled computer-aided diagnosis solution that automates interpretation of high resolution thermal images and identifies potential malignant lesions. The solution is low cost, easy to use, portable and is effective in all age groups. This paper presents the results of a retrospective comparative analysis of Thermalytix over Mammography and Clinical Breast Examination for breast cancer screening. Thermalytix was found to have better sensitivity than both the tests, with good specificity as well. In addition, Thermalytix identified all malignant patients without palpable lumps.
Keywords: Breast Cancer Screening, Radiology, Thermalytix, Artificial Intelligence, Thermography.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2802350 Tropical Peat Soil Stabilization using Class F Pond Ash from Coal Fired Power Plant
Authors: Kolay, P.K., Sii, H. Y., Taib, S.N.L.
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This paper presents the stabilization potential of Class F pond ash (PA) from a coal fired thermal power station on tropical peat soil. Peat or highly organic soils are well known for their high compressibility, natural moisture content, low shear strength and long-term settlement. This study investigates the effect of different amount (i.e., 5, 10, 15 and 20%) of PA on peat soil, collected from Sarawak, Malaysia, mainly compaction and unconfined compressive strength (UCS) properties. The amounts of PA added to the peat soil sample as percentage of the dry peat soil mass. With the increase in PA content, the maximum dry density (MDD) of peat soil increases, while the optimum moisture content (OMC) decreases. The UCS value of the peat soils increases significantly with the increase of PA content and also with curing periods. This improvement on compressive strength of tropical peat soils indicates that PA has the potential to be used as a stabilizer for tropical peat soil. Also, the use of PA in soil stabilization helps in reducing the pond volume and achieving environment friendly as well as a sustainable development of natural resources.Keywords: Compaction, Peat soil, Pond ash, Stabilization.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 3353349 Performance of Subcarrier- OCDMA System with Complementary Subtraction Detection Technique
Authors: R. K. Z. Sahbudin, M. K. Abdullah, M. Mokhtar, S. B. A. Anas, S. Hitam
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A subcarrier - spectral amplitude coding optical code division multiple access system using the Khazani-Syed code with Complementary subtraction detection technique is proposed. The proposed system has been analyzed by taking into account the effects of phase-induced intensity noise, shot noise, thermal noise and intermodulation distortion noise. The performance of the system has been compared with the spectral amplitude coding optical code division multiple access system using the Hadamard code and the Modified Quadratic Congruence code. The analysis shows that the proposed system can eliminate the multiple access interference using the Complementary subtraction detection technique, and hence improve the overall system performance.Keywords: Complementary subtraction, Khazani-Syed code, multiple access interference, phase-induced intensity noise
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1733348 Designing and Manufacturing High Voltage Pulse Generator with Adjustable Pulse and Monitoring Current and Voltage: Food Processing Application
Authors: H. Mirzaee, A. Pourzaki
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Using strength Pulse Electrical Field (PEF) in food industries is a non-thermal process that can deactivate microorganisms and increase penetration in plant and animals tissues without serious impact on food taste and quality. In this paper designing and fabricating of a PEF generator has been presented. Pulse generation methods have been surveyed and the best of them selected. The equipment by controller set can generate square pulse with adjustable parameters such as amplitude 1-5kV, frequency 0.1-10Hz, pulse width 10-100s, and duty cycle 0-100%. Setting the number of pulses, and presenting the output voltage and current waveforms on the oscilloscope screen are another advantages of this equipment. Finally, some food samples were tested that yielded the satisfactory results. PEF applying had considerable effects on potato, banana and purple cabbage. It caused increase Brix factor from 0.05 to 0.15 in potato solution. It is also so effective in extraction color material from purple cabbage. In the last experiment effects of PEF voltages on color extraction of saffron scum were surveyed (about 6% increasing yield).Keywords: PEF, Capacitor, Switch, IGBT
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 4205347 Characterization of Corn Cobs from Microwave and Potassium Hydroxide Pretreatment
Authors: Boonyisa Wanitwattanarumlug, Apanee Luengnaruemitchai, Sujitra Wongkasemjit
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The complexity of lignocellulosic biomass requires a pretreatment step to improve the yield of fermentable sugars. The efficient pretreatment of corn cobs using microwave and potassium hydroxide and enzymatic hydrolysis was investigated. The objective of this work was to characterize the optimal condition of pretreatment of corn cobs using microwave and potassium hydroxide enhance enzymatic hydrolysis. Corn cobs were submerged in different potassium hydroxide concentration at varies temperature and resident time. The pretreated corn cobs were hydrolyzed to produce the reducing sugar for analysis. The morphology and microstructure of samples were investigated by Thermal gravimetric analysis (TGA, scanning electron microscope (SEM), X-ray diffraction (XRD). The results showed that lignin and hemicellulose were removed by microwave/potassium hydroxide pretreatment. The crystallinity of the pretreated corn cobs was higher than the untreated. This method was compared with autoclave and conventional heating method. The results indicated that microwave-alkali treatment was an efficient way to improve the enzymatic hydrolysis rate by increasing its accessibility hydrolysis enzymes.Keywords: Corn cobs, Enzymatic hydrolysis, Microwave, Potassium hydroxide, Pretreatment.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2272346 Bed Site Selection by Wild Boar (Sus scrofa) in Baghshadi Protected Area, Yazd Province, Iran
Authors: S. Aghainajafizadeh, F. Heydari, H. Abbasian
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Populations of wild boar present in semi-arid of central Iran. We studied features influencing bed site selection by this species in semi-arid central steppe of Iran. Habitat features of the detected bed site were compared with randomly selected by quantifying number of habitat variables in semi- arid area in Iran. The results revealed that the most important influencing factors in bed site selection were vegetation cover, number of Artemisia sieberi, percentage cover and height of Acer cinerascens, percentage cover and height of Amygdalus scoparia. This is the first ecological study of the wild boar in a protected area of the semi desert biome of Iran. Sustainability of wild boar populations in this area dependent to shrubs of Amygdalus scoparia and Acer cinerascens for thermal and camouflage cover.
Keywords: Wild boar, Bed site selection, Yazd, Iran
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1286345 Automatic Generation Control of Interconnected Power System with Generation Rate Constraintsby Hybrid Neuro Fuzzy Approach
Authors: Gayadhar Panda, Sidhartha Panda, C. Ardil
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The design of Automatic Generation Control (AGC) system plays a vital role in automation of power system. This paper proposes Hybrid Neuro Fuzzy (HNF) approach for AGC of two-area interconnected reheat thermal power system with the consideration of Generation Rate Constraint (GRC). The advantage of proposed controller is that it can handle the system non-linearities and at the same time the proposed approach is faster than conventional controllers. The performance of HNF controller has been compared with that of both conventional Proportional Integral (PI) controller as well as Fuzzy Logic Controller (FLC) both in the absence and presence of Generation Rate Constraint (GRC). System performance is examined considering disturbance in each area of interconnected power system.
Keywords: Automatic Generation Control (AGC), Dynamic Response, Generation Rate Constraint (GRC), Proportional Integral(PI) Controller, Fuzzy Logic Controller (FLC), Hybrid Neuro-Fuzzy(HNF) Control, MATLAB/SIMULINK.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 4119344 Buckling Resistance of GFRP Sandwich Infill Panels with Different Cores under Increased Temperatures
Authors: Viriyavudh Sim, Woo Young Jung
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This paper presents numerical analysis in terms of buckling resistance of GFRP sandwich infill panels system under the influence of increased temperature on the foam core. Failure mode under in-plane compression is studied by means of numerical analysis with ABAQUS platform. Parameters considered in this study are contact length and both the type of foam for core and the variation of its module elastic under the thermal influence. Increment of temperature is considered in static cases and only applied to core. Indeed, it is proven that the effect of temperature alters the mechanical properties of the entire panel system. Moreover, the rises of temperature result in a decrease in strength of the panel. This is due to the polymeric nature of this material. Additionally, the contact length also displays the effect on performance of infill panel. Their significance factors are based on type of polymer for core. Therefore, by comparing difference type of core material, the variation can be reducing.Keywords: Buckling, contact length, foam core, temperature dependent.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1904343 Effect of Magnetic Field on the Biological Clock through the Radical Pair Mechanism
Authors: Chathurika D. Abeyrathne, Malka N. Halgamuge, Peter M. Farrell
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There is an ongoing controversy in the literature related to the biological effects of weak, low frequency electromagnetic fields. The physical arguments and interpretation of the experimental evidence are inconsistent, where some physical arguments and experimental demonstrations tend to reject the likelihood of any effect of the fields at extremely low level. The problem arises of explaining, how the low-energy influences of weak magnetic fields can compete with the thermal and electrical noise of cells at normal temperature using the theoretical studies. The magnetoreception in animals involve radical pair mechanism. The same mechanism has been shown to be involved in the circadian rhythm synchronization in mammals. These reactions can be influenced by the weak magnetic fields. Hence, it is postulated the biological clock can be affected by weak magnetic fields and these disruptions to the rhythm can cause adverse biological effects. In this paper, likelihood of altering the biological clock via the radical pair mechanism is analyzed to simplify these studies of controversy.Keywords: Bio-effect, biological clock, magnetoreception, radical pair mechanism, weak magnetic field.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2312342 High Temperature Oxidation of Cr-Steel Interconnects in Solid Oxide Fuel Cells
Authors: Saeed Ghali, Azza Ahmed, Taha Mattar
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Solid Oxide Fuel Cell (SOFC) is a promising solution for the energy resources leakage. Ferritic stainless steel becomes a suitable candidate for the SOFCs interconnects due to the recent advancements. Different steel alloys were designed to satisfy the needed characteristics in SOFCs interconnect as conductivity, thermal expansion and corrosion resistance. Refractory elements were used as alloying elements to satisfy the needed properties. The oxidation behaviour of the developed alloys was studied where the samples were heated for long time period at the maximum operating temperature to simulate the real working conditions. The formed scale and oxidized surface were investigated by SEM. Microstructure examination was carried out for some selected steel grades. The effect of alloying elements on the behaviour of the proposed interconnects material and the performance during the working conditions of the cells are explored and discussed. Refractory metals alloying of chromium steel seems to satisfy the needed characteristics in metallic interconnects.
Keywords: SOFCs, Cr-steel, interconnects, oxidation.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1214341 Investigation of Water Vapour Transport Properties of Gypsum Using Genetic Algorithm
Authors: Z. Pavlík, J. Žumár, M. Pavlíková, J. Kočí, R. Černý
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Water vapour transport properties of gypsum block are studied in dependence on relative humidity using inverse analysis based on genetic algorithm. The computational inverse analysis is performed for the relative humidity profiles measured along the longitudinal axis of a rod sample. Within the performed transient experiment, the studied sample is exposed to two environments with different relative humidity, whereas the temperature is kept constant. For the basic gypsum characterisation and for the assessment of input material parameters necessary for computational application of genetic algorithm, the basic material properties of gypsum are measured as well as its thermal and water vapour storage parameters. On the basis of application of genetic algorithm, the relative humidity dependent water vapour diffusion coefficient and water vapour diffusion resistance factor are calculated.Keywords: Water vapour transport, gypsum block, transient experiment, genetic algorithm.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1649340 MHD Natural Convection Flow of Tangent Hyperbolic Nanofluid Past a Vertical Permeable Cone
Authors: A. Mahdy
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In this paper, a non-similraity analysis has been presented to exhibit the two-dimensional boundary layer flow of magnetohydrodynamic (MHD) natural convection of tangent hyperbolic nanofluid nearby a vertical permeable cone in the presence of variable wall temperature impact. The mutated boundary layer nonlinear governing equations are solved numerically by the an efficient implicit finite difference procedure. For both nanofluid effective viscosity and nanofluid thermal conductivity, a number of experimental relations have been recognized. For characterizing the nanofluid, the compatible nanoparticle volume fraction model has been used. Nusselt number and skin friction coefficient are calculated for some values of Weissenberg number W, surface temperature exponent n, magnetic field parameter Mg, power law index m and Prandtl number Pr as functions of suction parameter. The rate of heat transfer from a vertical permeable cone in a regular fluid is less than that in nanofluids. A best convection has been presented by Copper nanoparticle among all the used nanoparticles.Keywords: Tangent hyperbolic nanofluid, finite difference, non-similarity, isothermal cone.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 772339 Biosecurity Control Systems in Two Phases for Poultry Farms
Authors: M. Peña Aguilar Juan, E. Nava Galván Claudia, Pastrana Palma Alberto
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In this work was developed and implemented a thermal fogging disinfection system to counteract pathogens from poultry feces in agribusiness farms, to reduce mortality rates and increase biosafety in them. The control system consists of two phases for the conditioning of the farm during the sanitary break. In the first phase, viral and bacterial inactivation was performed by treating the stool dry cleaning, along with the development of a specialized product that foster the generation of temperatures above 55 °C in less than 24 hr, for virus inactivation. In the second phase, a process for disinfection by fogging was implemented, along with the development of a specialized disinfectant that guarantee no risk for the operators’ health or birds. As a result of this process, it was possible to minimize the level of mortality of chickens on farms from 12% to 5.49%, representing a reduction of 6.51% in the death rate, through the formula applied to the treatment of poultry litter based on oxidising agents used as antiseptics, hydrogen peroxide solutions, glacial acetic acid and EDTA in order to act on bacteria, viruses, micro bacteria and spores.
Keywords: Innovation, triple-helix, innovation, poultry farms.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1445338 FEM Simulations to Study the Effects of Laser Power and Scan Speed on Molten Pool Size in Additive Manufacturing
Authors: Yee-Ting Lee, Jyun-Rong Zhuang, Wen-Hsin Hsieh, An-Shik Yang
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Additive manufacturing (AM) is increasingly crucial in biomedical and aerospace industries. As a recently developed AM technique, selective laser melting (SLM) has become a commercial method for various manufacturing processes. However, the molten pool configuration during SLM of metal powders is a decisive issue for the product quality. It is very important to investigate the heat transfer characteristics during the laser heating process. In this work, the finite element method (FEM) software ANSYS® (work bench module 16.0) was used to predict the unsteady temperature distribution for resolving molten pool dimensions with consideration of temperature-dependent thermal physical properties of TiAl6V4 at different laser powers and scanning speeds. The simulated results of the temperature distributions illustrated that the ratio of laser power to scanning speed can greatly influence the size of molten pool of titanium alloy powder for SLM development.
Keywords: Additive manufacturing, finite element method, molten pool dimensions, selective laser melting.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1640337 Behaviour of Base-Isolated Structures with High Initial Isolator Stiffness
Authors: Ajay Sharma, R.S. Jangid
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Analytical seismic response of multi-story building supported on base isolation system is investigated under real earthquake motion. The superstructure is idealized as a shear type flexible building with lateral degree-of-freedom at each floor. The force-deformation behaviour of the isolation system is modelled by the bi-linear behaviour which can be effectively used to model all isolation systems in practice. The governing equations of motion of the isolated structural system are derived. The response of the system is obtained numerically by step-by-method under three real recorded earthquake motions and pulse motions associated in the near-fault earthquake motion. The variation of the top floor acceleration, interstory drift, base shear and bearing displacement of the isolated building is studied under different initial stiffness of the bi-linear isolation system. It was observed that the high initial stiffness of the isolation system excites higher modes in base-isolated structure and generate floor accelerations and story drift. Such behaviour of the base-isolated building especially supported on sliding type of isolation systems can be detrimental to sensitive equipment installed in the building. On the other hand, the bearing displacement and base shear found to reduce marginally with the increase of the initial stiffness of the initial stiffness of the isolation system. Further, the above behaviour of the base-isolated building was observed for different parameters of the bearing (i.e. post-yield stiffness and characteristic strength) and earthquake motions (i.e. real time history as well as pulse type motion).Keywords: base isolation, base shear, bi-linear, earthquake, floor accelerations, inter-story drift, multi-story building, pulsemotion, stiffness ratio.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2298336 Nugget Formation during Resistance Spot Welding using Finite Element Model
Authors: Jawad Saleem, Abdul Majid, Kent Bertilsson, Torbjörn Carlberg, Nazar Ul Islam
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Resistance spot welding process comprises of electric, thermal and mechanical phenomenon, which makes this process complex and highly non-linear and thus, it becomes difficult to model it. In order to obtain good weld nugget during spot welding, hit and trial welds are usually done which is very costly. Therefore the numerical simulation research has been conducted to understand the whole process. In this paper three different cases were analyzed by varying the tip contact area and it was observed that, with the variation of tip contact area the nugget formation at the faying surface is affected. The tip contact area of the welding electrode becomes large with long welding cycles. Therefore in order to maintain consistency of nugget formation during the welding process, the current compensation in control feedback is required. If the contact area of the welding electrode tip is reduced, a large amount of current flows through the faying surface, as a result of which sputtering occurs.Keywords: Resistance spot welding, Finite element modeling, Nugget formation, Welding electrode, Numerical method simulation,
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 3776335 Theoretical Study of Flexible Edge Seals for Vacuum Glazing
Authors: Farid Arya, Trevor Hyde
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The development of vacuum glazing represents a significant advancement in the area of low heat loss glazing systems with the potential to substantially reduce building heating and cooling loads. Vacuum glazing consists of two or more glass panes hermetically sealed together around the edge with a vacuum gap between the panes. To avoid the glass panes from collapsing and touching each other under the influence of atmospheric pressure an array of support pillars is provided between the glass panes. A high level of thermal insulation is achieved by evacuating the spaces between the glass panes to a very low pressure which greatly reduces conduction and convection within the space; therefore heat transfer through this kind of glazing is significantly lower when compared with conventional insulating glazing. However, vacuum glazing is subject to inherent stresses due to atmospheric pressure and temperature differentials which can lead to fracture of the glass panes and failure of the edge seal. A flexible edge seal has been proposed to minimise the impact of these issues. In this paper, vacuum glazing system with rigid and flexible edge seals is theoretically studied and their advantages and disadvantages are discussed.Keywords: Flexible edge seal, stress, support pillar, vacuum glazing.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1251334 Effects of Viscous Dissipation and Concentration Based Internal Heat Source on Convective Instability in a Porous Medium with Throughflow
Authors: N. Deepika, P. A. L. Narayana
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Linear stability analysis of double diffusive convection in a horizontal porous layer saturated with fluid is examined by considering the effects of viscous dissipation, concentration based internal heat source and vertical throughflow. The basic steady state solution for Governing equations is derived. Linear stability analysis has been implemented numerically by using shooting and Runge-kutta methods. Critical thermal Rayleigh number Rac is obtained for various values of solutal Rayleigh number Sa, vertical Peclet number Pe, Gebhart number Ge, Lewis number Le and measure of concentration based internal heat source γ. It is observed that Ge has destabilizing effect for upward throughflow and stabilizing effect for downward throughflow. And γ has considerable destabilizing effect for upward throughflow and insignificant destabilizing effect for downward throughflow.Keywords: Porous medium, concentration based internal heat source, vertical throughflow, viscous dissipation.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1623333 PI Controller for Automatic Generation Control Based on Performance Indices
Authors: Kalyan Chatterjee
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The optimal design of PI controller for Automatic Generation Control in two area is presented in this paper. The concept of Dual mode control is applied in the PI controller, such that the proportional mode is made active when the rate of change of the error is sufficiently larger than a specified limit otherwise switched to the integral mode. A digital simulation is used in conjunction with the Hooke-Jeeve’s optimization technique to determine the optimum parameters (individual gain of proportional and integral controller) of the PI controller. Integrated Square of the Error (ISE), Integrated Time multiplied by Absolute Error(ITAE) , and Integrated Absolute Error(IAE) performance indices are considered to measure the appropriateness of the designed controller. The proposed controller are tested for a two area single nonreheat thermal system considering the practical aspect of the problem such as Deadband and Generation Rate Constraint(GRC). Simulation results show that dual mode with optimized values of the gains improved the control performance than the commonly used Variable Structure .
Keywords: Load Frequency Control, Area Control Error(ACE), Dual Mode PI Controller, Performance Index
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2101332 Comparison of Indoor and Outdoor Air Quality in Children Homes at Prenatal Period and One Year Old
Authors: S. Lakestani, B. Karakas, S. Acar Vaizoglu, B. Guciz Dogan, C. Guler, B. Sekerel, A. Taner, G. Gullu
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Abstract–Indoor air (VOCs) samples were collected simultaneously from variety of indoors (e.g. living rooms, baby-s rooms) and outdoor environments which were voluntarily selected from the houses in which pregnant residents live throughout Ankara. This is the first comprehensive study done in Turkey starting from prenatal period and continued till the babies had one year old. VOCs levels were measured over 76 homes. Air samples were collected in Tenax TA sorbent filled tubes with active sampling method and analyzed with Thermal Desorber and Gas Chromatography/Mass spectrometry (TD-GC/MS). At the first sampling period in the baby-s rooms maximum concentration of toluene was measured about 240.77μg.m-3 and in the living rooms maximum concentration of naphthalene was 180.24μg.m-3. At the second sampling period in the baby-s rooms maximum concentration of toluene was measured about 144.97μg.m-3 and in the living rooms maximum concentration of naphthalene was 247.89μg.m-3. Concentration of TVOCs in the first period was generally higher than the second period.Keywords: Indoor Air, Volatile Organic Compounds (VOCs), Gas Chromatography
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1994331 Long Term Stability of an Experimental Insulated-Model Salinity-Gradient Solar Pond
Authors: N. W. K. Jayatissa, R. Attalage, Prabath Hewageegana, P. A. A. Perera, M. A. Punyasena
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Per capita energy usage in any country is exponentially increasing with their development. As a result, the country’s dependence on the fossil fuels for energy generation is also increasing tremendously creating economic and environmental concerns. Tropical countries receive considerable amount of solar radiation throughout the year, use of solar energy with different energy storage and conversion methodologies is a viable solution to minimize the ever increasing demand for the depleting fossil fuels. Salinity gradient solar pond is one such solar energy application. This paper reports the characteristics and performance of a thermally insulated, experimental salinity-gradient solar pond, built at the premises of the University of Kelaniya, Sri Lanka. Particular stress is given to the behavior of the evolution of the three layer structure exist at the stable state of a salinity gradient solar pond over a long period of time, under different environmental conditions. The operational procedures required to maintain the long term thermal stability are also reported in this article.
Keywords: Salt-gradient, solar pond, solar radiation, renewable energy.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1598330 An Analysis of Dynamic Economic Dispatch Using Search Space Reduction Based Gravitational Search Algorithm
Authors: K. C. Meher, R. K. Swain, C. K. Chanda
Abstract:
This paper presents the performance analysis of dynamic search space reduction (DSR) based gravitational search algorithm (GSA) to solve dynamic economic dispatch of thermal generating units with valve point effects. Dynamic economic dispatch basically dictates the best setting of generator units with anticipated load demand over a definite period of time. In this paper, the presented technique is considered that deals an inequality constraints treatment mechanism known as DSR strategy to accelerate the optimization process. The presented method is demonstrated through five-unit test systems to verify its effectiveness and robustness. The simulation results are compared with other existing evolutionary methods reported in the literature. It is intuited from the comparison that the fuel cost and other performances of the presented approach yield fruitful results with marginal value of simulation time.Keywords: Dynamic economic dispatch, dynamic search space reduction strategy, gravitational search algorithm, ramp rate limits, valve-point effects.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1486329 Tool Condition Monitoring of Ceramic Inserted Tools in High Speed Machining through Image Processing
Authors: Javier A. Dominguez Caballero, Graeme A. Manson, Matthew B. Marshall
Abstract:
Cutting tools with ceramic inserts are often used in the process of machining many types of superalloy, mainly due to their high strength and thermal resistance. Nevertheless, during the cutting process, the plastic flow wear generated in these inserts enhances and propagates cracks due to high temperature and high mechanical stress. This leads to a very variable failure of the cutting tool. This article explores the relationship between the continuous wear that ceramic SiAlON (solid solutions based on the Si3N4 structure) inserts experience during a high-speed machining process and the evolution of sparks created during the same process. These sparks were analysed through pictures of the cutting process recorded using an SLR camera. Features relating to the intensity and area of the cutting sparks were extracted from the individual pictures using image processing techniques. These features were then related to the ceramic insert’s crater wear area.Keywords: Ceramic cutting tools, high speed machining, image processing, tool condition monitoring, tool wear.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2175328 Construction and Performance Characterization of the Looped-Tube Travelling-Wave Thermoacoustic Engine with Ceramic Regenerator
Authors: Abdulrahman S. Abduljalil, Zhibin Yu, Artur J. Jaworski, Lei Shi
Abstract:
In a travelling wave thermoacoustic device, the regenerator sandwiched between a pair of (hot and cold) heat exchangers constitutes the so-called thermoacoustic core, where the thermoacoustic energy conversion from heat to acoustic power takes place. The temperature gradient along the regenerator caused by the two heat exchangers excites and maintains the acoustic wave in the resonator. The devices are called travelling wave thermoacoustic systems because the phase angle difference between the pressure and velocity oscillation is close to zero in the regenerator. This paper presents the construction and testing of a thermoacoustic engine equipped with a ceramic regenerator, made from a ceramic material that is usually used as catalyst substrate in vehicles- exhaust systems, with fine square channels (900 cells per square inch). The testing includes the onset temperature difference (minimum temperature difference required to start the acoustic oscillation in an engine), the acoustic power output, thermal efficiency and the temperature profile along the regenerator.Keywords: Regenerator, Temperature gradient, Thermoacoustic, Travelling-wave.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2258327 Influence of Machining Process on Surface Integrity of Plasma Coating
Authors: T. Zlámal, J. Petrů, M. Pagáč, P. Krajkovič
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For the required function of components with the thermal spray coating, it is necessary to perform additional machining of the coated surface. The paper deals with assessing the surface integrity of Metco 2042, a plasma sprayed coating, after its machining. The selected plasma sprayed coating serves as an abradable sealing coating in a jet engine. Therefore, the spray and its surface must meet high quality and functional requirements. Plasma sprayed coatings are characterized by lamellar structure, which requires a special approach to their machining. Therefore, the experimental part involves the set-up of special cutting tools and cutting parameters under which the applied coating was machined. For the assessment of suitably set machining parameters, selected parameters of surface integrity were measured and evaluated during the experiment. To determine the size of surface irregularities and the effect of the selected machining technology on the sprayed coating surface, the surface roughness parameters Ra and Rz were measured. Furthermore, the measurement of sprayed coating surface hardness by the HR 15 Y method before and after machining process was used to determine the surface strengthening. The changes of strengthening were detected after the machining. The impact of chosen cutting parameters on the surface roughness after the machining was not proven.
Keywords: Machining, plasma sprayed coating, surface integrity, strengthening.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1002