Search results for: vortex dynamics

Authors: Ramdas Sonawane, Mahaveer Gadiya

Abstract:

The control problem associated with nuclear dynamics is represented by nonlinear integro-differential equation with additive controls. To control chain reaction, certain amount of neutrons is added into (or withdrawn out of) chamber as and when required. It is not realistic. So, we can think of controlling the reactor dynamics by bilinear control, which enters the system as coefficient of state. In this paper, we study the approximate and exact controllability of parabolic integro-differential equation controlled by bilinear control with non-homogeneous boundary conditions in bounded domain. We prove the existence of control and propose an explicit control strategy.

Keywords: approximate control, exact control, bilinear control, nuclear dynamics, integro-differential equations

Procedia PDF Downloads 408

Authors: Rajesh Bhatt, Dilip Kumar Maiti

Abstract:

The incompressible shear flow past a square cylinder placed parallel to a plane wall of side length A in presence of upstream rectangular cylinder of height 0.5A and width 0.25A in an inline tandem arrangement are numerically investigated using finite volume method. The discretized equations are solved by an implicit, time-marching, pressure correction based SIMPLE algorithm. This study provides the qualitative insight in to the dependency of basic structure (i.e. vortex shedding or suppression) of flow over the downstream square cylinder and the upstream rectangular cylinder (and hence the aerodynamic characteristics) on inter-cylinder spacing (S) and Reynolds number (Re). The spacing between the cylinders is varied systematically from S = 0.5A to S = 7.0A so the sensitivity of the flow structure between the cylinders can be inspected. A sudden jump in strouhal number is observed, which shows the transition of flow pattern in the wake of the cylinders. The results are presented at Re = 100 and 200 in term of Strouhal number, RMS and mean of lift and drag coefficients and contour plots for different spacing.

Keywords: square cylinder, vortex shedding, isolated, tandem arrangement, spacing distance

Procedia PDF Downloads 520

Authors: Radha H. R., Krupakara P. V.

Abstract:

Metal matrix composites are attracting today's manufacturers of many automobile parts so that they lost longer and their properties can be tailored according to the requirement. In this paper an attempt has been made to study the corrosion characteristics of Aluminium 6061 / quartz metal matrix composites in alkali medium like sodium hydroxide solutions. Metal matrix composites are heterogeneous mixtures of a matrix and reinforcement. In this work the matrix selected is Aluminium 6061 alloy which is commercially available and the reinforcement selected is quartz particulates of 50-80 micron size which is available in plenty in and around Bangalore district, India. Composites containing Aluminium 6061 with 2, 4 and 6 weight percent of quartz are manufactured by liquid melt metallurgy technique using vortex method. Corrosion tests like static weight loss and open circuit potential tests are conducted in different concentrated solutions of sodium hydroxide. To compare the results the matrix Aluminium 6061 is also casted in the same way. Specimens for the test are prepared according to ASTM standards. In all the tests the metal matrix composites showed better corrosion resistance than matrix alloy.

Keywords: aluminium 6061, corrosion, quartz, vortex

Procedia PDF Downloads 380

Authors: Y. El Khchine, M. Sriti

Abstract:

In the present work, the forced convection heat transfer and fluid flow past an unconfined semi-circular cylinder is investigated. The two-dimensional simulation is employed for Reynolds numbers ranging from 10 ≤ Re ≤ 200, employing air (Pr = 0.71) as an operating fluid with Newtonian constant physics property. Continuity, momentum, and energy equations with appropriate boundary conditions are solved using the Computational Fluid Dynamics (CFD) solver Ansys Fluent. Various parameters flow such as lift, drag, pressure, skin friction coefficients, Nusselt number, Strouhal number, and vortex strength are calculated. The transition from steady to time-periodic flow occurs between Re=60 and 80. The effect of the Reynolds number on heat transfer is discussed. Finally, a developed correlation of Nusselt and Strouhal numbers is presented.

Keywords: forced convection, semi-circular cylinder, Nusselt number, Prandtl number

Procedia PDF Downloads 85

Authors: Mohammad A. Bani-Khaled

Abstract:

In this work we use the Discrete Proper Orthogonal Decomposition transform to characterize the properties of coupled dynamics in thin-walled beams by exploiting numerical simulations obtained from finite element simulations. The outcomes of the will improve our understanding of the linear and nonlinear coupled behavior of thin-walled beams structures. Thin-walled beams have widespread usage in modern engineering application in both large scale structures (aeronautical structures), as well as in nano-structures (nano-tubes). Therefore, detailed knowledge in regard to the properties of coupled vibrations and buckling in these structures are of great interest in the research community. Due to the geometric complexity in the overall structure and in particular in the cross-sections it is necessary to involve computational mechanics to numerically simulate the dynamics. In using numerical computational techniques, it is not necessary to over simplify a model in order to solve the equations of motions. Computational dynamics methods produce databases of controlled resolution in time and space. These numerical databases contain information on the properties of the coupled dynamics. In order to extract the system dynamic properties and strength of coupling among the various fields of the motion, processing techniques are required. Time- Proper Orthogonal Decomposition transform is a powerful tool for processing databases for the dynamics. It will be used to study the coupled dynamics of thin-walled basic structures. These structures are ideal to form a basis for a systematic study of coupled dynamics in structures of complex geometry.

Keywords: coupled dynamics, geometric complexity, proper orthogonal decomposition (POD), thin walled beams

Procedia PDF Downloads 393

Authors: Pardeep Bishnoi, Mayank Srivastava, Mrityunjay Kumar Sinha

Abstract:

This article represents the numerical investigation of the pressure and velocity field variation of the dynamics of pendant drop formation through a capillary tube. Numerical simulations are executed using volume of fluid (VOF) method in the computational fluid dynamics (CFD). In this problem, Non Newtonian fluid is considered as dispersed fluid whereas air is considered as a continuous fluid. Pressure contours at various time steps expose that pressure varies nearly hydrostatically at each step of the dynamics of drop formation. A result also shows the pressure variation of the liquid droplet during free fall in the computational domain. The evacuation of the fluid from the necking region is also shown by the contour of the velocity field. The role of surface tension in the Pressure contour of the dynamics of drop formation is also studied.

Keywords: pressure contour, surface tension, volume of fluid, velocity field

Procedia PDF Downloads 372

Authors: Mohammed Traeq Shukri

Abstract:

Scour is a natural phenomenon caused by the erosive action of flowing stream on alluvial beds, which removes the sediment around or near structures located in flowing water. It means the lowering of the riverbed level by water erosions such that there is a tendency to expose the foundations of a structure. It is the result of the erosive action of flowing water, excavating and carrying away material from the bed and banks of streams and from around the piers of bridges. The failure of bridges due to excessive local scour during floods poses a challenging problem to hydraulic engineers. The failure of bridges piers is due to many reasons such as localized scour combined with general riverbed degradation. In this paper, we try to estimate the temporal variation of scour depth at non-uniform cylindrical bridge pier, by experimental work in civil engineering hydraulic laboratories of Gaziantep University on a channel have dimensions of 8.3m length, 0.8m width and 0.9m depth. The experiments will be carried on 20 cm depth of sediment layer having d50=0.4 mm. Three bridge pier shapes having different scaled models will be constructed in a 1.5m of test section in the channel.

Keywords: scour, local scour, bridge piers, scour depth, vortex, horseshoe vortex

Procedia PDF Downloads 143

Authors: Meziane Belkacem

Abstract:

We aim at converting the original 3D Lorenz-Haken equations, which describe laser dynamics –in terms of self-pulsing and chaos- into 2-second-order differential equations, out of which we extract the so far missing mathematics and corroborations with respect to nonlinear interactions. Leaning on basic trigonometry, we pull out important outcomes; a fundamental result attributes chaos to forbidden periodic solutions inside some precisely delimited region of the control parameter space that governs the bewildering dynamics.

Keywords: Physics, optics, nonlinear dynamics, chaos

Procedia PDF Downloads 126

Authors: Desmond Appiah, Fan Zhang, Shouqi Yuan, Wei Xueyuan, Stephen N. Asomani

Abstract:

The side channel pump has distinctive hydraulic performance characteristics over other vane pumps because of its generation of high pressure heads in only one impeller revolution. Hence, there is soaring utilization and application in the fields of petrochemical, food processing fields, automotive and aerospace fuel pumping where high heads are required at low flows. The side channel pump is characterized by unstable flow because after fluid flows into the impeller passage, it moves into the side channel and comes back to the impeller again and then moves to the next circulation. Consequently, the flow leaves the side channel pump following a helical path. However, the pressure fluctuation exhibited in the flow greatly contributes to the unwanted noise and vibration which is associated with the flow. In this paper, a side channel pump prototype was examined thoroughly through numerical calculations based on SST k-ω turbulence model to ascertain the pressure fluctuation behavior. The pressure fluctuation intensity of the 3D unstable flow dynamics were carefully investigated under different working conditions 0.8QBEP, 1.0 QBEP and 1.2QBEP. The results showed that the pressure fluctuation distribution around the pressure side of the blade is greater than the suction side at the impeller and side channel interface (z=0) for all three operating conditions. Part-load condition 0.8QBEP recorded the highest pressure fluctuation distribution because of the high circulation velocity thus causing an intense exchanged flow between the impeller and side channel. Time and frequency domains spectra of the pressure fluctuation patterns in the impeller and the side channel were also analyzed under the best efficiency point value, QBEP using the solution from the numerical calculations. It was observed from the time-domain analysis that the pressure fluctuation characteristics in the impeller flow passage increased steadily until the flow reached the interrupter which separates low-pressure at the inflow from high pressure at the outflow. The pressure fluctuation amplitudes in the frequency domain spectrum at the different monitoring points depicted a gentle decreasing trend of the pressure amplitudes which was common among the operating conditions. The frequency domain also revealed that the main excitation frequencies occurred at 600Hz, 1200Hz, and 1800Hz and continued in the integers of the rotating shaft frequency. Also, the mass flow exchange plots indicated that the side channel pump is characterized with many vortex flows. Operating conditions 0.8QBEP, 1.0 QBEP depicted less and similar vortex flow while 1.2Q recorded many vortex flows around the inflow, middle and outflow regions. The results of the numerical calculations were finally verified experimentally. The performance characteristics curves from the simulated results showed that 0.8QBEP working condition recorded a head increase of 43.03% and efficiency decrease of 6.73% compared to 1.0QBEP. It can be concluded that for industrial applications where the high heads are mostly required, the side channel pump can be designed to operate at part-load conditions. This paper can serve as a source of information in order to optimize a reliable performance and widen the applications of the side channel pumps.

Keywords: exchanged flow, pressure fluctuation, numerical simulation, side channel pump

Procedia PDF Downloads 101

Authors: Iwan Setiawan, Bobby Eka Gunara, Katshuhiro Nakamura

Abstract:

The theory to accelerate system on quantum dynamics has been constructed to get the desired wave function on shorter time. This theory is developed on adiabatic quantum dynamics which any regulation is done on wave function that satisfies Schrödinger equation. We show accelerated manipulation of WFs with the use of a parameter-dependent in asymmetric double-well potential and also when it’s influenced by electromagnetic fields.

Keywords: driving potential, Adiabatic Quantum Dynamics, regulation, electromagnetic field

Procedia PDF Downloads 304

Authors: Christian Angerer, Markus Lienkamp

Abstract:

Electric vehicles offer a high variety of possible drivetrain topologies with up to 4 motors. Multi-motor-designs can have several advantages regarding traction, vehicle dynamics, safety and even efficiency. With a rising number of motors, the whole drivetrain becomes more complex. All permutations of gearings, drivetrain-layouts, motor-types and –sizes lead up in a very large solution space. Single elements of this solution space can be analyzed by simulation methods. In addition to longitudinal vehicle behavior, which most optimization-approaches are restricted to, also lateral dynamics are important for vehicle dynamics, stability and efficiency. In order to compete large solution spaces and to find an optimal result, genetic algorithm based optimization is state-of-the-art. As lateral dynamics simulation is way more CPU-intensive, optimization takes much more time than in case of longitudinal-only simulation. Therefore, this paper shows an approach how to create meta-models from a 14-degree of freedom vehicle model in order to enable a numerically efficient drivetrain-layout optimization process under consideration of lateral dynamics. Different meta-modelling approaches such as neural networks or DoE are implemented and comparatively discussed.

Keywords: driving dynamics, drivetrain layout, genetic optimization, meta-modeling, lateral dynamicx

Procedia PDF Downloads 382

Authors: P. V. Krupakara

Abstract:

This paper deals with the high corrosion resistance developed by the hybrid metal matrix composites when compared with that of matrix alloy. Matrix selected is Al6061. Reinforcements selected are graphite and red mud particulates. The composites are prepared using liquid melt metallurgy technique using vortex method. Metal matrix composites containing 2 percent graphite and 2 percent red mud, 2 percent graphite and 4 percent red mud, 2 percent graphite and 6 percent of red mud are prepared. Bar castings are cut into cylindrical discs of 20mm diameter and 20mm thickness. Corrosion tests were conducted at room temperature (230 °C) using conventional weight loss method according to ASTM G69-80. The corrodents used for the test were hydrochloric acid solution of different concentrations. Specimens were tested for every 24 hours interval up to 96 hours. Four specimens for each condition and time were immersed in corrodent. In each case the corrosion rate decreases with increase in exposure time for matrix and metal matrix composites whatever may be the concentration of hydrochloric acid. This may be due to aluminium, which may induce passivation due to development of non-porous layer. As red mud content increases the composites become corrosion resistant due to insulating nature of ceramic material red mud and less exposure of matrix alloy in those metal matrix composites.

Keywords: Al6061, graphite, passivation, red mud, vortex

Procedia PDF Downloads 506

Authors: Boguslaw Schreyer

Abstract:

In this paper, a general dynamical model is derived using the Lagrange formalism. The two masses: sprang and unsprang are included in a six-degree of freedom model for a sprung mass. The unsprung mass is included and shown only in a simplified model, although its equations have also been derived by an author. The simplified equations, more suitable for the computer model of robot’s dynamics are also shown.

Keywords: dynamics, mobile, robot, wheeled mobile robots

Procedia PDF Downloads 310

Authors: Christopher I. Ifeacho, Adeleke Omolade

Abstract:

The paper examines the relationship between energy price dynamics and green growth in Sub Sahara African Countries. The quest for adopting green energy in order to improve green growth that can engender sustainability and stability has received more attention from researchers in recent times. This study uses a panel autoregressive distributed lag approach to investigate this relationship. Findings from the result showed that energy price dynamics and exchange rates have more short-run significant impacts on green growth in individual countries rather than the pooled result. Furthermore, the long-run result confirmed that inflation and capital have a significant long-run relationship with green growth. The causality test result revealed the existence of a bi-directional relationship between green growth and energy price dynamics. The study recommends caution in a currency devaluation and improvement in renewable energy production in the Sub Sahara Africa in order to achieve sustainable green growth.

Keywords: green growth, energy price dynamics, Sub Saharan Africa, relationship

Procedia PDF Downloads 57

Authors: Takashi Shimizu, Tomoaki Hashimoto

Abstract:

Recently, crystal growth technologies have made progress by the requirement for the high quality of crystal materials. To control the crystal growth dynamics actively by external forces is useuful for reducing composition non-uniformity. In this study, a control method based on model predictive control using thermal inputs is proposed for crystal growth dynamics of semiconductor materials. The control system of crystal growth dynamics considered here is governed by the continuity, momentum, energy, and mass transport equations. To establish the control method for such thermal fluid systems, we adopt model predictive control known as a kind of optimal feedback control in which the control performance over a finite future is optimized with a performance index that has a moving initial time and terminal time. The objective of this study is to establish a model predictive control method for crystal growth dynamics of semiconductor materials.

Keywords: model predictive control, optimal control, process control, crystal growth

Procedia PDF Downloads 326

Authors: Luong A. Nguyen, Elihu Deneke, Thomas L. Harman

Abstract:

This paper describes a multibody dynamics algorithm formulated for parallel implementation on multiprocessor computing platforms using the divide-and-conquer approach. The system of interest is a general topology of rigid and elastic articulated bodies with or without loops. The algorithm is an extension of Featherstone’s divide and conquer approach to include the flexible-body dynamics formulation. The equations of motion, configured for the International Space Station (ISS) with its robotic manipulator arm as a system of articulated flexible bodies, are implemented in separate computer processors. The performance of this divide-and-conquer algorithm implementation in multiple processors is compared with an existing method implemented on a single processor.

Keywords: multibody dynamics, multiple processors, multithreading, divide-and-conquer algorithm, computational efficiency, flexible body dynamics

Procedia PDF Downloads 293

Authors: B. Yanıktepe, C. Özalp, B. Şahin

Abstract:

Delta wing planform is an essential aerodynamic configuration, which could be effectively used at relatively high angles of attack than conventional wings in subsonic flow conditions. The flow over delta wings can be characterized by a pair of leading edge vortices emanating from wing apex. Boundary layer separation causes these vortical structures formed by rolling up of viscous flow sheet. This flow separation mechanism is occurred due to angle of attack and sharp leading edges of the delta wing. Therefore, complexity and variety in planform designs rise to catch the best under abnormal flow conditions. The present experimental study investigates the near surface flow structure and aerodynamic flow characteristics of X-45 type non-slender delta wing planform using dye visualization, Stereoscopic Particle Image Velocimetry (stereo-PIV). The instantaneous images are acquired on the plan-view plane within 5o≤α≤20o to calculate the time-averaged flow data. It can be concluded that vortical flow with a pair of well-defined LEVs over X-45 develop at very low angles of attack, secondary vortex are also evident and form close to the wing surface similar to delta and lambda planforms. The stall occurs at an angle of attack α=32o.

Keywords: aerodynamic, delta wing, PIV, vortex breakdown

Procedia PDF Downloads 386

Authors: Wataru Nakamura, Tomoaki Hashimoto, Liang-Kuang Chen

Abstract:

This paper provides a state estimation method for automatic control systems of nonlinear vehicle dynamics. A nonlinear tire model is employed to represent the realistic behavior of a vehicle. In general, all the state variables of control systems are not precisedly known, because those variables are observed through output sensors and limited parts of them might be only measurable. Hence, automatic control systems must incorporate some type of state estimation. It is needed to establish a state estimation method for nonlinear vehicle dynamics with restricted measurable state variables. For this purpose, unscented Kalman filter method is applied in this study for estimating the state variables of nonlinear vehicle dynamics. The objective of this paper is to propose a state estimation method using unscented Kalman filter for nonlinear vehicle dynamics. The effectiveness of the proposed method is verified by numerical simulations.

Keywords: state estimation, control systems, observer systems, nonlinear systems

Procedia PDF Downloads 107

Authors: Tai-Young Park, Yangjin Park

Abstract:

Introduction: This study analyzed a family therapy case involving a female client in her thirties with panic disorder (PD) in South Korea. We identified five stages of the psychological process in the development of PD and examined external situations, family dynamics, and psychological experiences at each stage. Method: The client, mother, sister, and husband participated in therapy. Researchers analyzed the transcripts, notes, and video recordings of the therapy sessions. A thematic analysis was used to examine the data and display our findings using a network. Results: The developmental process of PD was as follows: (1) formation of anxiety, (2) sheltered life, (3) crisis, (4) loss of safe haven, and (5) inner breakdown. Conclusion: The family dynamics that developed as a result of coping with external situations in each stage contributed to clients’ psychological experiences. These psychological experiences triggered anxiety, which led to the development of PD. Moreover, this study empirically suggests that family dynamics can be associated with a person’s internal experiences that could lead to PD. Our findings highlight the significance of functional family dynamics and coping patterns when facing difficult external situations or crises.

Keywords: developmental process, family therapy, panic disorder, psychological dynamics

Procedia PDF Downloads 63

Authors: Arturo Ayala-Hernandez, Humberto Hijar

Abstract:

We propose a new alternative method for imposing fluid-solid boundary conditions in simulations of Multiparticle Collision Dynamics. Our method is based on the introduction of an explicit potential force acting between the fluid particles and a surface representing a solid boundary. We show that our method can be used in simulations of plane Poiseuille flows. Important quantities characterizing the flow and the fluid-solid interaction like the slip coefficient at the solid boundary and the effective viscosity of the fluid, are measured in terms of the set of independent parameters defining the numerical implementation. We find that our method can be used to simulate the correct hydrodynamic flow within a wide range of values of these parameters.

Keywords: Multiparticle Collision Dynamics, fluid-solid, boundary conditions, molecular dynamics

Procedia PDF Downloads 499

Authors: S. Jakšić, B. Žmuk

Abstract:

The paper investigates the key factors of export dynamics for a set of Central and Southeast European (CSEE) countries in the context of current economic and financial crisis. In order to model the export dynamics a Global Vector Auto Regressive (GVAR) model is defined. As opposed to models which model each country separately, the GVAR combines all country models in a global model which enables obtaining important information on spill-over effects in the context of globalization and rising international linkages. The results of the study indicate that for most of the CSEE countries, exports are mainly driven by domestic shocks, both in the short run and in the long run. This study is the first application of the GVAR model to studying the export dynamics in the CSEE countries and therefore the results of the study present an important empirical contribution.

Keywords: export, GFEVD, global VAR, international trade, weak exogeneity

Procedia PDF Downloads 272

Authors: Mohammad Mashud, S. M. Nahid Hasan

Abstract:

The aim of the research work is to modify the NACA 4215 airfoil with flap and rotary cylinder at the leading edge of the airfoil and experimentally study the static pressure distribution over the airfoil completed with flap and leading-edge vortex generator. In this research, NACA 4215 wing model has been constructed by generating the profile geometry using the standard equations and design software such as AutoCAD and SolidWorks. To perform the experiment, three wooden models are prepared and tested in subsonic wind tunnel. The experiments were carried out in various angles of attack. Flap angle and momentum injection rate are changed to observe the characteristics of pressure distribution. In this research, a new concept of flow separation control mechanism has been introduced to improve the aerodynamic characteristics of airfoil. Control of flow separation over airfoil which experiences a vortex generator (rotating cylinder) at the leading edge of airfoil is experimentally simulated under the effects of momentum injection. The experimental results show that the flow separation control is possible by the proposed mechanism, and benefits can be achieved by momentum injection technique. The wing performance is significantly improved due to control of flow separation by momentum injection method.

Keywords: airfoil, momentum injection, flap, pressure distribution

Procedia PDF Downloads 116

Authors: Katja Ignatieva, Patrick Wong

Abstract:

We investigated the dynamics of high frequency energy prices, including crude oil and electricity prices. The returns of underlying quantities are modelled using various parametric models such as stochastic framework with jumps and stochastic volatility (SVCJ) as well as non-parametric alternatives, which are purely data driven and do not require specification of the drift or the diffusion coefficient function. Using different statistical criteria, we investigate the performance of considered parametric and nonparametric models in their ability to forecast price series and volatilities. Our models incorporate possible seasonalities in the underlying dynamics and utilise advanced estimation techniques for the dynamics of energy prices.

Keywords: stochastic volatility, affine jump-diffusion models, high frequency data, model specification, markov chain monte carlo

Procedia PDF Downloads 68

Authors: Nashrawan Naser Taha, Andrew M. Cox

Abstract:

In a multi-cultural learning context, where ties are weak and dynamic, combining qualitative with quantitative research methods may be more effective. Such a combination may also allow us to answer different types of question, such as about people’s perception of the network. In this study the use of observation, interviews and photos were explored as ways of enhancing data from social network questionnaires. Integrating all of these methods was found to enhance the quality of data collected and its accuracy, also providing a richer story of the network dynamics and the factors that shaped these changes over time.

Keywords: mixed methods, social network analysis, multi-cultural learning, social network dynamics

Procedia PDF Downloads 487

Authors: Abhishek Kumar Gupta

Abstract:

Atomistic Molecular Dynamics (MD) Simulations have been performed to study the effect of monovalent salt i.e. NaCl concentration (Cs) and chain degree of neutralization (f) on the structure and dynamics of anionic poly(methacrylic acid) (PMA) in dilute aqueous solutions. In the present study, the attention is to unveil the conformational structure, hydrogen-bonding, local polyion-counterion structure, h-bond dynamics, chain dynamics and thermodynamic enthalpy of solvation of a-PMA in dilute aqueous solutions as a function of salt concentration, Cs and f. The results have revealed that at low salt concentration, the conformational radius of gyration (Rg) increases and then decreases reaching a maximum in agreement with the reported light scattering experimental results. The Rg at f = 1 shows a continual decrease and acquire a plateau value at higher salt concentration in agreement with results obtained by light scattering experiments. The radial distribution functions between PMA, salt and water atoms has been computed with respect to atom and centre-of-mass to understand the intermolecular structure in detail. The results pertaining to PMA chain conformations and hydrogen bond autocorrelation function showcasing the h-bond dynamics will be presented. The results pertaining to chain dynamics will be presented. The results pertaining to counterion condensation on the PMA chain shows greater condensation of Na+ ions on to the carboxylate ions with increase in salt concentration. Moreover, the solvation enthalpy of the system as a function of salt concentration will be presented.

Keywords: conformations, molecular dynamics simulations, NaCl concentration, radial distribution functions

Procedia PDF Downloads 78

Authors: Pawan Kumar Pant, Bhanu Gupta, S. R. Kale, S. V. Veeravalli

Abstract:

In many countries, buses are the principal means of transport, of which a majority are naturally ventilated with open windows. The design of this ventilation has little scientific basis and to address this problem a study has been undertaken involving both experiments and numerical simulations. The flow pattern inside and around of an open window bus with passengers has been investigated in detail. A full scale three-dimensional numerical simulation has been used for a) a bus with closed windows and b) with open windows. In either simulation, the bus had 58 seated passengers. The bus dimensions used were 2500 mm wide × 2500 mm high (exterior) × 10500 mm long and its speed was set at 40 km/h. In both cases, the flow separates at the top front edge forming a vortex and reattaches close to the mid-length. This attached flow separates once more as it leaves the bus. However, the strength and shape of the vortices at the top front and wake region is different for both cases. The streamline pattern around the bus is also different for the two cases. For the bus with open windows, the dominant airflow inside the bus is from the rear to the front of the bus and air velocity at the face level of the passengers was found to be 1/10th of the free stream velocity. These findings are in good agreement with flow visualization experiments performed in a water channel at 10 m/s, and with smoke/tuft visualizations in a wind tunnel with a free-stream velocity of approximately 40 km/h on a 1:25 scaled Perspex model.

Keywords: air flow, moving bus, open windows, vortex, wind tunnel

Procedia PDF Downloads 197

Authors: Nicole Kaye A. Callanta, Shalimar B. Baruang, Anne Edelienne P. Tadena, Imelu G. Mordeno, Odessa May D. Escalona

Abstract:

Untold numbers of children and adolescents around the world are exposed increasingly to the war on a daily basis. These experiences shape how they will view themselves, others, and the world. A wealth of studies have shown the role of family dynamics in the development of children’s attitudes, particularly their social behaviors. This specific study, however, contends that family dynamics influence peace and conflict resolution attitude and further asserts that it is brought about by the degree of emotional regulation strategies they use. Utilising purposive sampling, adolescent participant-respondents were from different schools in Southern Philipines, specifically of the cities of Marawi and Iligan, where exposure to warring clans, internal struggle between the Philippine Military and insurgencies, and the recent Marawi Seige caused by Al-Qaeda and ISIS-spawned terrorism. Results showed emotional regulation strategies mediate the relationship between family dynamics, particularly on family cohesion, and attitude towards peace. Thus implying the association between family cohesion and attitude towards peace strengthens with the use of emotional regulation strategies.

Keywords: attitude towards peace, emotional regulation strategies, family cohesion, family dynamics

Procedia PDF Downloads 146

Authors: Ahmad Kavousi, Ali Delaviz

Abstract:

In this project, the landing process is simulated by using of multi-body dynamics commercial software. Various factors, including landing situations, aircraft structures and climate are used in this simulation. The purpose of this project is to determine the forces exerted on the aircraft landing gears in landing process in various landing conditions. For this purpose, the ADAMS multi-body dynamics software is used. Different scenarios based on FAR-25, including level landing, tail-down landing, crab landing are simulated. Results of dynamic simulation software with landing load factor obtained from the analytical solution are compared. The effect of fuselage elasticity on the landing load is studied. For this purpose, both of elastic and rigid body assumptions are used in the simulation process, and the results are compared and some conclusions are made.

Keywords: landing gear, landing process, aircraft, multi-body dynamics

Procedia PDF Downloads 474

Authors: M. W. Sun, Y. Zhang, L. M. Zhang, Z. H. Wang, Z. Q. Chen

Abstract:

In the realm of flight control, the Proportional- Derivative (PD) control is still widely used for the attitude control in practice, particularly for the pitch control, and the attitude dynamics using PD controller should be investigated deeply. According to the empirical knowledge about the unstable flight dynamics, the control parameter combination conditions to generate sole or finite number of closed-loop oscillations, which is a quite smooth response and is more preferred by practitioners, are presented in analytical or numerical manners. To analyze the effects of the combination conditions of the control parameters, the roots of several polynomials are sought to obtain feasible solutions. These conditions can also be plotted in a 2-D plane which makes the conditions be more explicit by using multiple interval operations. Finally, numerical examples are used to validate the proposed methods and some comparisons are also performed.

Keywords: attitude control, dynamic performance, numerical solving method, interval, unstable flight dynamics

Procedia PDF Downloads 541

Authors: Rui Mao, Heming Ji, Xiaoyu Wang

Abstract:

Keystroke dynamics are widely used in identity recognition. It has the advantage that the individual typing rhythm is difficult to imitate. It also supports continuous authentication through the keyboard without extra devices. The existing keystroke dynamics authentication methods based on machine learning have a drawback in supporting relatively complex scenarios with massive data. There are drawbacks to both feature extraction and model optimization in these methods. To overcome the above weakness, an authentication model of keystroke dynamics based on deep learning is proposed. The model uses feature vectors formed by keystroke content and keystroke time. It ensures efficient continuous authentication by cooperating attention mechanisms with the combination of CNN and Bi-LSTM. The model has been tested with Open Data Buffalo dataset, and the result shows that the FRR is 3.09%, FAR is 3.03%, and EER is 4.23%. This proves that the model is efficient and accurate on continuous authentication.

Keywords: keystroke dynamics, identity authentication, deep learning, CNN, LSTM

Procedia PDF Downloads 125