Search results for: Regular Surface
763 Irreversibility and Electrochemical Modeling of GT-SOFC Hybrid System and Parametric Analysis on Performance of Fuel Cell
Authors: R. Mahjoub, K. Maghsoudi Mehraban
Abstract:
Since the heart of the hybrid system is the fuel cell and it has vital impact on efficiency and performance of cycle, in this study, the major modeling of electrochemical reaction within the fuel cell is analyzed. Also, solid oxide fuel cell is integrated with the gas turbine and thermodynamic analysis on different elements of hybrid system is applied. Next, in predefined operational points of hybrid cycle, the simulation results are obtained. Then, different source of irreversibility in fuel cell is modeled and influence of different major parameters on different irreversibility is computed and applied. Then, the effect of important parameters such as thickness and surface of electrolyte fuel cell are simulated in fuel cell and its dependency to these parameters is explained. At the end of the paper, different impact of parameters on fuel cell with a gas turbine and current density and voltage of fuel cell are simulated.Keywords: Electrochemical analysis, Gas turbine, Hybrid system, Irreversibility analysis.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1497762 Investigation of the Effect of Cavitator Angle and Dimensions for a Supercavitating Vehicle
Authors: Sri Raman A., A.K.Ghosh
Abstract:
At very high speeds, bubbles form in the underwater vehicles because of sharp trailing edges or of places where the local pressure is lower than the vapor pressure. These bubbles are called cavities and the size of the cavities grows as the velocity increases. A properly designed cavitator can induce the formation of a single big cavity all over the vehicle. Such a vehicle travelling in the vaporous cavity is called a supercavitating vehicle and the present research work mainly focuses on the dynamic modeling of such vehicles. Cavitation of the fins is also accounted and the effect of the same on trajectory is well explained. The entire dynamics has been developed using the state space approach and emphasis is given on the effect of size and angle of attack of the cavitator. Control law has been established for the motion of the vehicle using Non-linear Dynamic Inverse (NDI) with cavitator as the control surface.
Keywords: High speed underwater vehicle, Non-Linear Dynamic Inverse (NDI), six-dof modeling, Supercavitation, Torpedo.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 71576761 Identification of Ductile Damage Parameters for Austenitic Steel
Authors: J. Dzugan, M. Spaniel, P. Konopík, J. Ruzicka, J. Kuzelka
Abstract:
The modeling of inelastic behavior of plastic materials requires measurements providing information on material response to different multiaxial loading conditions. Different triaxiality conditions and values of Lode parameters have to be covered for complex description of the material plastic behavior. Samples geometries providing material plastic behavoiur over the range of interest are proposed with the use of FEM analysis. Round samples with 3 different notches and smooth surface are used together with butterfly type of samples tested at angle ranging for 0 to 90°. Identification of ductile damage parameters is carried out on the basis of obtained experimental data for austenitic stainless steel. The obtained material plastic damage parameters are subsequently applied to FEM simulation of notched CT normally samples used for fracture mechanics testing and results from the simulation are compared with real tests.Keywords: baqus, austenitic steel, computer simulation, ductile damage, triaxiality
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 3722760 Study on Mixed Convection Heat Transfer in Vertical Ducts with Radiation Effects
Authors: G. Rajamohan, N. Ramesh, P. Kumar
Abstract:
Experiments have been performed to investigate the radiation effects on mixed convection heat transfer for thermally developing airflow in vertical ducts with two differentially heated isothermal walls and two adiabatic walls. The investigation covers the Reynolds number Re = 800 to Re = 2900, heat flux varied from 256 W/m2 to 863 W/m2, hot wall temperature ranges from 27°C to 100 °C, aspect ratios 1 & 0.5 and the emissivity of internal walls are 0.05 and 0.85. In the present study, combined flow visualization was conducted to observe the flow patterns. The effect of surface temperature along the walls was studied to investigate the local Nusselt number variation within the duct. The result shows that flow condition and radiation significantly affect the total Nusselt number and tends to reduce the buoyancy condition.
Keywords: Mixed convection, vertical duct, thermally developing and radiation effects.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2745759 Microwave-Assisted Fabrication of Visible-Light Activated BiOBr-Nanoplate Photocatalyst
Authors: Meichen Lee, Michael K. H. Leung
Abstract:
In recent years, visible-light activated photocatalysis has become a major field of intense researches for the higher efficiency of solar energy utilizations. Many attempts have been made on the modification of wide band gap semiconductors, while more and more efforts emphasize on cost-effective synthesis of visible-light activated catalysts. In this work, BiOBr nanoplates with band gap of visible-light range are synthesized through a promising microwave solvothermal method. The treatment time period and temperature dependent BiOBr nanosheets of various particle sizes are investigated through SEM. BiOBr synthesized under the condition of 160°C for 60 mins shows the most uniform particle sizes around 311 nm and the highest surface-to-volume ratio on account of its smallest average particle sizes compared with others. It exhibits the best photocatalytic behavior among all samples in RhB degradation.
Keywords: Microwave solvothermal process, nanoplates, solar energy, visible-light photocatalysis.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 991758 Use of Zeolite and Surfactant Modified Zeolite as Ion Exchangers to Control Nitrate Leaching
Authors: R. Malekian, J. Abedi-Koupai, S. S. Eslamian
Abstract:
Nitrogen loss from irrigated cropland, particularly sandy soils, significantly contributes to nitrate (NO3 -) levels in surface and groundwaters. Thus, it is of great interest to use inexpensive natural products that can increase the fertilizer efficiency and decrease nitrate leaching. In this study, the ability of natural Iranian zeolite clinoptilolite (Cp) and surfactant modified zeolite clinoptilolite (SMZ) to remove NH4 + and NO3 -, respectively, from aqueous solutions was determined. The feasibility of using Cp and SMZ as soil amendment to reduce nitrate leaching from soil using lysimeters was also investigated. Zeolite showed 10.23% to 88.42% NH4 + removal efficiency over a wide range of initial NH4 + concentrations. Nitrate removal efficiency by SMZ was 32.26% to 82.26%. Field study results showed that Cp and SMZ significantly (p < 0.05) reduced leachate NO3-N concentration compared to control. There was no significant difference between maximum and mean leachate NO3-N concentration of SMZ lysimeters and those of Cp lysimeters.Keywords: Ammonium removal, Leaching, Nitrate removal, Surfactant modified zeolite
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2744757 Modeling and Simulation of Axial Fan Using CFD
Authors: Hemant Kumawat
Abstract:
Axial flow fans, while incapable of developing high pressures, they are well suitable for handling large volumes of air at relatively low pressures. In general, they are low in cost and possess good efficiency, and can have blades of airfoil shape. Axial flow fans show good efficiencies, and can operate at high static pressures if such operation is necessary. Our objective is to model and analyze the flow through AXIAL FANS using CFD Software and draw inference from the obtained results, so as to get maximum efficiency. The performance of an axial fan was simulated using CFD and the effect of variation of different parameters such as the blade number, noise level, velocity, temperature and pressure distribution on the blade surface was studied. This paper aims to present a final 3D CAD model of axial flow fan. Adapting this model to the available components in the market, the first optimization was done. After this step, CFX flow solver is used to do the necessary numerical analyses on the aerodynamic performance of this model. This analysis results in a final optimization of the proposed 3D model which is presented in this article.
Keywords: ANSYS CFX, Axial Fan, Computational Fluid Dynamics (CFD), Optimization.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 11179756 Experimental Studies on Multiphase Flow in Porous Media and Pore Wettability
Authors: Xingxun Li, Xianfeng Fan
Abstract:
Multiphase flow transport in porous medium is very common and significant in science and engineering applications. For example, in CO2 Storage and Enhanced Oil Recovery processes, CO2 has to be delivered to the pore spaces in reservoirs and aquifers. CO2 storage and enhance oil recovery are actually displacement processes, in which oil or water is displaced by CO2. This displacement is controlled by pore size, chemical and physical properties of pore surfaces and fluids, and also pore wettability. In this study, a technique was developed to measure the pressure profile for driving gas/liquid to displace water in pores. Through this pressure profile, the impact of pore size on the multiphase flow transport and displacement can be analyzed. The other rig developed can be used to measure the static and dynamic pore wettability and investigate the effects of pore size, surface tension, viscosity and chemical structure of liquids on pore wettability.
Keywords: Enhanced oil recovery, Multiphase flow, Pore size, Pore wettability
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2315755 Experimental Study of Performance of a Counter Flow Ranque-Hilsch Vortex Tube with Inner Threaded Body
Authors: Gürol Önal, Kevser Dincer
Abstract:
In this experimental study, performance of a counter flow Ranque-Hilsch vortex tube (RHVT) with threads cut on its inner surface was investigated experimentally (pitch is 1 and 2 mm). The inner diameter of the vortex tube used was D=9 mm and the ratio of the tube’s length to diameter was L/D=12. The experimental system was a thermodynamic open system. Flow was controlled by a valve on the hot outlet side, where the valve was changed from a nearly closed position to its nearly open position. Fraction of cold flow (ξ) = 0.1-0.9, was determined under 300 and 350 kPa pressurized air. All experimental data were compared with each other, the maximum heating performance of the RHVT system was found to be 38.2 oC and the maximum cooling performance of the RHVT in this study was found to be -30.9 oC at pitch 1 mm.
Keywords: Ranque-Hilsch vortex tube, heating, cooling, temperature separation.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2863754 Mathematical Models for Overall Gas Transfer Coefficient Using Different Theories and Evaluating Their Measurement Accuracy
Authors: Shashank.B. Thakre, Lalit.B. Bhuyar, Samir.J. Deshmukh
Abstract:
Oxygen transfer, the process by which oxygen is transferred from the gaseous to liquid phase, is a vital part of the waste water treatment process. Because of low solubility of oxygen and consequent low rate of oxygen transfer, sufficient oxygen to meet the requirement of aerobic waste does not enter through normal surface air water interface. Many theories have come up in explaining the mechanism of gas transfer and absorption of non-reacting gases in a liquid, of out of which, Two film theory is important. An exiting mathematical model determines approximate value of Overall Gas Transfer coefficient. The Overall Gas Transfer coefficient, in case of Penetration theory, is 1.13 time more than that obtained in case of Two film theory. The difference is due to the difference in assumptions in the two theories. The paper aims at development of mathematical model which determines the value of Overall Gas Transfer coefficient with greater accuracy than the existing model.Keywords: Theories, Dissolved oxygen, Mathematical model, Gas Transfer coefficient, Accuracy.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1544753 Frozen Fish: Control of Glazing Operation
Authors: Tânia Manso, Luís Teixeira, Paula M. Reis Correia
Abstract:
Glazing is a process used to reduce undesirable drying or dehydration of fish during frozen or cold storage. To evaluate the effect of the time/ temperature binomial of the cryogenic frozen tunnel in the amount of glazing watera Central Composite Rotatable Design was used, with application of the Response Surface Methodology. The results reveal that the time/ temperature obtained for pink cusk-eel in experimental conditions for glazing water are similar to the industrial process, but for red fish and merluza the industrial process needs some adjustments. Control charts were established and implementedto control the amount of glazing water on sardine and merluza. They show that the freezing process was statistically controlled but there were some tendencies that must be analyzed, since the trend of sample mean values approached either of the limits, mainly in merluza. Thus, appropriate actions must be taken, in order to improve the process.
Keywords: Control charts, frozen fish, glazing, RSM.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 4430752 A Parametric Study on the Backwater Level Due to a Bridge Constriction
Authors: S. Atabay, T. A. Ali, Md. M. Mortula
Abstract:
This paper presents the results and findings from a parametric study on the water surface elevation at upstream of bridge constriction for subcritical flow. In this study, the influence of Manning's Roughness Coefficient of main channel (nmc) and floodplain (nfp), and bridge opening (b) flow rate (Q), contraction (kcon) and expansion coefficients (kexp) were investigated on backwater level. The DECK bridge models with different span widths and without any pier were investigated within the two stage channel having various roughness conditions. One of the most commonly used commercial one-dimensional HEC-RAS model was used in this parametric study. This study showed that the effects of main channel roughness (nmc) and flow rate (Q) on the backwater level are much higher than those of the floodplain roughness (nfp). Bridge opening (b) with contraction (kcon) and expansion coefficients (kexp) have very little effect on the backwater level within this range of parameters.
Keywords: Bridge backwater, parametric study and waterways.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2487751 A New Analytical Approach to Reconstruct Residual Stresses Due to Turning Process
Authors: G.H. Farrahi, S.A. Faghidian, D.J. Smith
Abstract:
A thin layer on the component surface can be found with high tensile residual stresses, due to turning operations, which can dangerously affect the fatigue performance of the component. In this paper an analytical approach is presented to reconstruct the residual stress field from a limited incomplete set of measurements. Airy stress function is used as the primary unknown to directly solve the equilibrium equations and satisfying the boundary conditions. In this new method there exists the flexibility to impose the physical conditions that govern the behavior of residual stress to achieve a meaningful complete stress field. The analysis is also coupled to a least squares approximation and a regularization method to provide stability of the inverse problem. The power of this new method is then demonstrated by analyzing some experimental measurements and achieving a good agreement between the model prediction and the results obtained from residual stress measurement.Keywords: Residual stress, Limited measurements, Inverse problems, Turning process.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1419750 Preparation of Computer Model of the Aircraft for Numerical Aeroelasticity Tests – Flutter
Authors: M. Rychlik, R. Roszak, M. Morzynski, M. Nowak, H. Hausa, K. Kotecki
Abstract:
Article presents the geometry and structure reconstruction procedure of the aircraft model for flatter research (based on the I22-IRYDA aircraft). For reconstruction the Reverse Engineering techniques and advanced surface modeling CAD tools are used. Authors discuss all stages of data acquisition process, computation and analysis of measured data. For acquisition the three dimensional structured light scanner was used. In the further sections, details of reconstruction process are present. Geometry reconstruction procedure transform measured input data (points cloud) into the three dimensional parametric computer model (NURBS solid model) which is compatible with CAD systems. Parallel to the geometry of the aircraft, the internal structure (structural model) are extracted and modeled. In last chapter the evaluation of obtained models are discussed.Keywords: computer modeling, numerical simulation, Reverse Engineering, structural model
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1749749 CO2 Sequestration Potential of Construction and Demolition Alkaline Waste Material in Indian Perspective
Authors: G.Anjali, M.Bhavya, N.Arvind Kumar
Abstract:
In order to avoid the potentially devastating consequences of global warming and climate change, the carbon dioxide “CO2" emissions caused due to anthropogenic activities must be reduced considerably. This paper presents the first study examining the feasibility of carbon sequestration in construction and demolition “C&D" waste. Experiments were carried out in a self fabricated Batch Reactor at 40ºC, relative humidity of 50-70%, and flow rate of CO2 at 10L/min for 1 hour for water-to-solids ratio of 0.2 to 1.2. The effect of surface area was found by comparing the theoretical extent of carbonation of two different sieve sizes (0.3mm and 2.36mm) of C&D waste. A 38.44% of the theoretical extent of carbonation equating to 4% CO2 sequestration extent was obtained for C&D waste sample for 0.3mm sieve size. Qualitative, quantitative and morphological analyses were done to validate carbonate formation using X-ray diffraction “X.R.D.," thermal gravimetric analysis “T.G.A., “X-Ray Fluorescence Spectroscopy “X.R.F.," and scanning electron microscopy “S.E.M".Keywords: Alkaline waste, construction and demolition waste, CO2 sequestration, mineral carbonation.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2007748 Modelling of Heating and Evaporation of Biodiesel Fuel Droplets
Authors: Mansour Al Qubeissi, Sergei S. Sazhin, Cyril Crua, Morgan R. Heikal
Abstract:
This paper presents the application of the Discrete Component Model for heating and evaporation to multi-component biodiesel fuel droplets in direct injection internal combustion engines. This model takes into account the effects of temperature gradient, recirculation and species diffusion inside droplets. A distinctive feature of the model used in the analysis is that it is based on the analytical solutions to the temperature and species diffusion equations inside the droplets. Nineteen types of biodiesel fuels are considered. It is shown that a simplistic model, based on the approximation of biodiesel fuel by a single component or ignoring the diffusion of components of biodiesel fuel, leads to noticeable errors in predicted droplet evaporation time and time evolution of droplet surface temperature and radius.
Keywords: Heat/Mass Transfer, Biodiesel, Multi-component Fuel, Droplet, Evaporation.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2791747 Computational Investigations of Concrete Footing Rotational Rigidity
Authors: E. S. Fraser, G. P. A. G. van Zijl
Abstract:
In many buildings we rely on large footings to offer structural stability. Designers often compensate for the lack of knowledge available with regard to foundation-soil interaction by furnishing structures with overly large footings. This may lead to a significant increase in building expenditures if many large foundations are present. This paper describes the interface material law that governs the behavior along the contact surface of adjacent materials, and the behavior of a large foundation under ultimate limit loading. A case study is chosen that represents a common foundation-soil system frequently used in general practice and therefore relevant to other structures. Investigations include compressing versus uplifting wind forces, alterations to the foundation size and subgrade compositions, the role of the slab stiffness and presence and the effect of commonly used structural joints and connections. These investigations aim to provide the reader with an objective design approach, efficiently preventing structural instability.Keywords: Computational investigation of footing rotation.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1588746 The Different Roles between Sodium and Potassium Ions in Ion Exchange of WO3/SiO2 Catalysts
Authors: K. Pipitthapan, S. Maksasithorn, P. Praserthdam, J. Panpranot, K. Suriye, S. Kunjara Na Ayudhya
Abstract:
WO3/SiO2 catalysts were modified by an ion exchange method with sodium hydroxide or potassium hydroxide solution. The performance of the modified catalysts was tested in the metathesis of ethylene and trans-2-butene to propylene. During ion exchange, sodium and potassium ions played different roles. Sodium modified catalysts revealed constant trans-2-butene conversion and propylene selectivity when the concentrations of sodium in the solution were varied. In contrast, potassium modified catalysts showed reduction of the conversion and increase of the selectivity. From these results, potassium hydroxide may affect the transformation of tungsten oxide active species, resulting in the decrease in conversion whereas sodium hydroxide did not. Moreover, the modification of catalysts by this method improved the catalyst stability by lowering the amount of coke deposited on the catalyst surface.Keywords: Acid sites, alkali metals, isomerization, metathesis.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1707745 Metal-Semiconductor-Metal Photodetector Based On Porous In0.08Ga0.92N
Authors: Saleh H. Abud, Z. Hassan, F. K. Yam
Abstract:
Characteristics of MSM photodetector based on a porous In0.08Ga0.92N thin film were reported. Nanoporous structures of n-type In0.08Ga0.92N/AlN/Si thin films were synthesized by photoelectrochemical (PEC) etching at a ratio of 1:4 of HF:C2H5OH solution for 15min. The structural and optical properties of pre- and post-etched thin films were investigated. Field emission scanning electron microscope and atomic force microscope images showed that the pre-etched thin film has a sufficiently smooth surface over a large region and the roughness increased for porous film. Blue shift has been observed in photoluminescence emission peak at 300 K for porous sample. The photoluminescence intensity of the porous film indicated that the optical properties have been enhanced. A high work function metals (Pt and Ni) were deposited as a metal contact on the porous films. The rise and recovery times of the devices were investigated at 390nm chopped light. Finally, the sensitivity and quantum efficiency were also studied.
Keywords: Porous InGaN, photoluminescence, SMS photodetector.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2023744 A Proper Design of Wind Turbine Grounding Systems under Lightning
Authors: M. A. Abd-Allah, Mahmoud N. Ali, A. Said
Abstract:
Lightning protection systems (LPS) for wind power generation is becoming an important public issue. A serious damage of blades, accidents where low-voltage and control circuit breakdowns are frequently occur in many wind farms. A grounding system is one of the most important components required for appropriate LPSs in wind turbines WTs. Proper design of a wind turbine grounding system is demanding and several factors for the proper and effective implementation must taken into account. In this paper proposed procedure of proper design of grounding systems for a wind turbine was introduced. This procedure depends on measuring of ground current of simulated wind farm under lightning taking into consideration the soil ionization. The procedure also includes the Ground Potential Rise (GPR) and the voltage distributions at ground surface level and Touch potential. In particular, the contribution of mitigating techniques, such as rings, rods and the proposed design were investigated.
Keywords: WTs, LPS, GPR, Grounding System, Mitigating techniques.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 5220743 Effect of Vitamin D3 on Polycystic Ovary Syndrome Prognosis, Anthropometric and Body Composition Parameters of Overweight Women: A Randomized, Placebo-Controlled Clinical Trial
Authors: Nahla Al-Bayyari, Rae’d Hailat
Abstract:
Vitamin D deficiency and overweight are common in women suffering from polycystic ovary syndrome (PCOS). Weight gain in PCOS is an important factor for the development of menstrual dysfunction and signs of hyperandrogenism and alopecia. Features of PCOS such as oligomenorrhea can be predicted by anthropometric measurements as body mass index (BMI). Therefore, the aim of this trial was to study the effect of 50,000 IU/week of vitamin D₃ supplementation on the body composition and on the anthropometric measurements of overweight women with PCOS and to examine the impact of this effect on ovaries ultrasonography and menstrual cycle regularity. The study design was a prospective randomized, double-blinded placebo-controlled clinical trial conducted on 60 overweight Jordanian women aged (18-49) years with PCOS and vitamin D deficiency. The study participants were divided into two groups; vitamin D group (n = 30) who were assigned to receive 50,000 IU/week of vitamin D₃ and placebo group (n = 30) who were assigned to receive placebo tablets orally for 90 days. The anthropometric measurements and body composition were measured at baseline and after treatment for the PCOS and vitamin D deficient women. Also, assessment of the participants’ picture of ovaries by ultrasound and menstrual cycle regulatory were performed before and after treatment. Results showed that there were no significant (p > 0.05) differences between the placebo and vitamin D group basal 25(OH)D levels, body composition and anthropometric parameters. After treatment, vitamin D group serum levels of 25(OH)D increased (12.5 ± 0.61 to 50.2 ± 2.04 ng/mL, (p < 0.001), and decreased (50.2 ± 2.04 to 48.2 ± 2.03 ng/mL, p < 0.001) after 14 days of vitamin D₃ treatment cessation. There were no significant changes in the placebo group. In the vitamin D group, there were significant (p < 0.001) decreases in body weight, BMI, waist, and hip circumferences and fat mass. In addition, there were significant increases (p < 0.05) in fat free mass and total body water. These improvements in both anthropometric and body composition as well as in 25(OH)D concentrations, resulted in significant improvements in the picture of PCOS women ovaries ultrasonography and in menstrual cycle regularity, where nearly most of them (93%) had regular cycles after vitamin D₃ supplementation. In the placebo group, there were only significant decreases (p < 0.05) in waist and hip circumferences. It can be concluded that vitamin D supplementation improving serum 25(OH)D levels and PCOS prognosis by reducing body weight of overweight PCOS women and regulating their menstrual cycle.Keywords: Anthropometric, overweight, polycystic ovary syndrome, vitamin D3.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 835742 Effect of Natural Animal Fillers on Polymer Rheology Behaviour
Authors: M. Seidl, J. Bobek, P. Lenfeld, L. Běhálek, A. Ausperger
Abstract:
This paper deals with the evaluation of flow properties of polymeric matrix with natural animal fillers. Technical university of Liberec cooperates on the long-term development of “green materials“ that should replace conventionally used materials (especially in automotive industry). Natural fibres (of animal and plant origin) from all over the world are collected and adapted (drying, cutting etc.) for extrusion processing. Inside the extruder these natural additives are blended with polymeric (synthetic and biodegradable - PLA) matrix and created compound is subsequently cut for pellets in the wet way. These green materials with unique recipes are then studied and their mechanical, physical and processing properties are determined. The main goal of this research is to develop new ecological materials very similar to unfilled polymers. In this article the rheological behaviour of chosen natural animal fibres is introduced considering their shape and surface that were observed with use of SEM microscopy.Keywords: Polypropylene matrix, Green polymers, Rheology, Natural animal fibres.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2185741 Sliding Mode Position Control for Permanent Magnet Synchronous Motors Based On Passivity Approach
Authors: Jenn-Yih Chen, Bean-Yin Lee, Yuan-Chuan Hsu, Jui-Cheng Lin, Kuang-Chyi Lee
Abstract:
In this paper, a sliding mode control method based on the passivity approach is proposed to control the position of surface-mounted permanent magnet synchronous motors (PMSMs). Firstly, the dynamics of a PMSM was proved to be strictly passive. The position controller with an adaptive law was used to estimate the load torque to eliminate the chattering effects associated with the conventional sliding mode controller. The stability analysis of the overall position control system was carried out by adopting the passivity theorem instead of Lyapunov-type arguments. Finally, experimental results were provided to show that the good position tracking can be obtained, and exhibit robustness in the variations of the motor parameters and load torque disturbances.
Keywords: Adaptive law, passivity theorem, permanent magnet synchronous motor, sliding mode control.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2120740 Unsteady Free Convection Flow Over a Three-Dimensional Stagnation Point With Internal Heat Generation or Absorption
Authors: Mohd Ariff Admon, Abdul Rahman Mohd Kasim, Sharidan Shafie
Abstract:
This paper considers the effect of heat generation proportional l to (T - T∞ )p , where T is the local temperature and T∞ is the ambient temperature, in unsteady free convection flow near the stagnation point region of a three-dimensional body. The fluid is considered in an ambient fluid under the assumption of a step change in the surface temperature of the body. The non-linear coupled partial differential equations governing the free convection flow are solved numerically using an implicit finite-difference method for different values of the governing parameters entering these equations. The results for the flow and heat characteristics when p ≤ 2 show that the transition from the initial unsteady-state flow to the final steadystate flow takes place smoothly. The behavior of the flow is seen strongly depend on the exponent p.Keywords: Free convection, Boundary layer flow, Stagnationpoint, Heat generation
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2250739 Developing Models for Predicting Physiologically Impaired Arm Reaching Paths
Authors: Nina Robson, Kenneth John Faller II, Vishalkumar Ahir, Mustafa Mhawesh, Reza Langari
Abstract:
This paper describes the development of a model of an impaired human arm performing a reaching motion, which will be used to predict hand path trajectories for people with reduced arm joint mobility. Assuming that the arm was in contact with a surface during the entire movement, the contact conditions at the initial and final task locations were determined and used to generate the entire trajectory. The model was validated by comparing it to experimental data, which simulated an arm joint impairment by physically constraining the joint motion with a brace. Future research will include using the model in the development of physical training protocols that avoid early recruitment of “healthy” Degrees-Of-Freedom (DOF) for reaching motions, thus facilitating an Active Range-Of-Motion Recovery (AROM) for a particular impaired joint.Keywords: Higher order kinematic specifications, human motor coordination, impaired movement, kinematic synthesis.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1081738 Numerical Investigation on Latent Heat Storage Unit of Different Configurations
Authors: Manish K Rathod, Jyotirmay Banerjee
Abstract:
The storage of thermal energy as a latent heat of phase change material (PCM) has created considerable interest among researchers in recent times. Here, an attempt is made to carry out numerical investigations to analyze the performance of latent heat storage units (LHSU) employing phase change material. The mathematical model developed is based on an enthalpy formulation. Freezing time of PCM packed in three different shaped containers viz. rectangular, cylindrical and cylindrical shell is compared. The model is validated with the results available in the literature. Results show that for the same mass of PCM and surface area of heat transfer, cylindrical shell container takes the least time for freezing the PCM and this geometric effect is more pronounced with an increase in the thickness of the shell than that of length of the shell.Keywords: Enthalpy Formulation, Latent heat storage unit(LHSU), Numerical Model, Phase change material (PCM)
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2506737 Parameters Influencing the Output Precision of a Lens-Lens Beam Generator Solar Concentrator
Authors: M. Tawfik, X. Tonnellier, C. Sansom
Abstract:
The Lens-Lens Beam Generator (LLBG) is a Fresnel-based optical concentrating technique which provides flexibility in selecting the solar receiver location compared to conventional techniques through generating a powerful concentrated collimated solar beam. In order to achieve that, two successive lenses are used and followed by a flat mirror. Hence the generated beam emerging from the LLBG has a high power flux which impinges on the target receiver, it is important to determine the precision of the system output. In this present work, mathematical investigation of different parameters affecting the precision of the output beam is carried out. These parameters include: Deflection in sun-facing lens and its holding arm, delay in updating the solar tracking system, and the flat mirror surface flatness. Moreover, relationships that describe the power lost due to the effect of each parameter are derived in this study.
Keywords: Fresnel lens, LLBG, solar concentrator, solar tracking.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1136736 Monitoring of Water Pollution and Its Consequences: An Overview
Authors: N. Singh, N. Sharma, J. K. Katnoria
Abstract:
Water a vital component for all living forms is derived from variety of sources, including surface water (rivers, lakes, reservoirs and ponds) and ground water (aquifers). Over the years of time, water bodies are subjected to human interference regularly resulting in deterioration of water quality. Therefore, pollution of water bodies has become matter of global concern. As the water quality closely relate to human health, water analysis before usage is of immense importance. Improper management of water bodies can cause serious problems in availability and quality of water. The quality of water may be described according to their physico-chemical and microbiological characteristics. For effective maintenance of water quality through appropriate control measures, continuous monitoring of metals, physico-chemical and biological parameter is essential for the establishment of baseline data for the water quality in any study area. The present study has focused on to explore the status of water pollution in various areas and to estimate the magnitude of its toxicity using different bioassay.
Keywords: Genotoxicity, Heavy metals, Mutagenicity, Physico-chemical analysis.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 3545735 Parking Space Detection and Trajectory Tracking Control for Vehicle Auto-Parking
Authors: Shiuh-Jer Huang, Yu-Sheng Hsu
Abstract:
On-board available parking space detecting system, parking trajectory planning and tracking control mechanism are the key components of vehicle backward auto-parking system. Firstly, pair of ultrasonic sensors is installed on each side of vehicle body surface to detect the relative distance between ego-car and surrounding obstacle. The dimension of a found empty space can be calculated based on vehicle speed and the time history of ultrasonic sensor detecting information. This result can be used for constructing the 2D vehicle environmental map and available parking type judgment. Finally, the auto-parking controller executes the on-line optimal parking trajectory planning based on this 2D environmental map, and monitors the real-time vehicle parking trajectory tracking control. This low cost auto-parking system was tested on a model car.Keywords: Vehicle auto-parking, parking space detection, parking path tracking, intelligent fuzzy controller.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1445734 Design Optimization of Aerocapture with Aerodynamic-Environment-Adaptive Variable Geometry Flexible Aeroshell
Authors: Naohiko Honma, Kojiro Suzuki
Abstract:
This paper proposes the concept of aerocapture with aerodynamic-environment-adaptive variable geometry flexible aeroshell that vehicle deploys. The flexible membrane is composed of thin-layer film or textile as its aeroshell in order to solve some problems obstructing realization of aerocapture technique. Multi-objective optimization study is conducted to investigate solutions and derive design guidelines. As a result, solutions which can avoid aerodynamic heating and enlarge the corridor width up to 10% are obtained successfully, so that the effectiveness of this concept can be demonstrated. The deformation-use optimum solution changes its drag coefficient from 1.6 to 1.1, along with the change in dynamic pressure. Moreover, optimization results show that deformation-use solution requires the membrane for which upper temperature limit and strain limit are more than 700 K and 120%, respectively, and elasticity (Young-s modulus) is of order of 106 Pa.Keywords: Aerocapture, flexible aeroshell, optimization, response surface methodology.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1988