This document discusses pattern formation in crowd dynamics. It begins with an introduction to crowd dynamics and then discusses two specific patterns: lane formation and freezing-by-heating transition. Lane formation occurs when pedestrians walking in opposite directions spontaneously form lanes to allow for more efficient movement. Freezing-by-heating transition refers to the phenomenon where increasing noise or energy in a crowd leads to the formation of orderly lanes, rather than disorder. The document explores mathematical modeling of these patterns using particle simulation models.
This study deals with the active control of the dynamic response of a string with fixed ends and mass
loaded by a point mass. It has been controlled actively by means of a feed forward control method. A point mass of a
string is considered as a vibrating receiver which be forced to vibrate by a vibrating source being positioned on the
string. By analyzing the motion of a string, the equation of motion for a string was derived by using a method of
variation of parameters. To define the optimal conditions of a controller, the cost function, which denotes the dynamic
response at the point mass of a string was evaluated numerically. The possibility of reduction of a dynamic response
was found to depend on the location of a control force, the magnitude of a point mass and a forcing frequency
This talk is about the analysis of nonlinear energy harvesters. A particular example of an inverted beam harvester proposed by our group has been discussed in details.
Efficient mode-matching analysis of 2-D scattering by periodic array of circu...Yong Heui Cho
This document proposes a new mode-matching method for analyzing periodic arrays of circular cylinders with different materials. It uses a common-area concept and infinitesimal perfect magnetic conductor wires to match boundary conditions between rectangular and cylindrical coordinate systems. This allows derivation of scattering equations for the arrays. The solutions are compared to other results to validate the method. It can be used to study resonance characteristics of nanostructures and scattering behavior at different frequencies.
Fourier-transform analysis of a ridge waveguide and a rectangular coaxial lineYong Heui Cho
This document presents a new technique for analyzing ridge waveguides and rectangular coaxial lines using Fourier transforms. It transforms the structures into equivalent periodic transmission lines using image theory. It represents the fields using Fourier transforms and derives dispersion relations in rigorous yet simple series forms. Numerical results show fast convergence that agrees with other methods. The technique is applicable to other shielded transmission line structures.
This document discusses vibration energy harvesting in uncertain environments. It begins with an introduction that describes piezoelectric vibration energy harvesting and the importance of considering uncertainty in both the input excitation and system parameters. It then presents single degree of freedom electromechanical models for linear and nonlinear energy harvesting systems. Optimal energy harvesting is analyzed for a linear system with a circuit without an inductor, where the mean harvested power is derived under Gaussian excitation.
The document discusses the concept of derivative as a rate of change. It defines the average rate of change and instantaneous rate of change over an interval and as the limit as the interval approaches zero respectively. It provides examples of calculating average and instantaneous rates of change from graphs and data tables.
This study deals with the active control of the dynamic response of a string with fixed ends and mass
loaded by a point mass. It has been controlled actively by means of a feed forward control method. A point mass of a
string is considered as a vibrating receiver which be forced to vibrate by a vibrating source being positioned on the
string. By analyzing the motion of a string, the equation of motion for a string was derived by using a method of
variation of parameters. To define the optimal conditions of a controller, the cost function, which denotes the dynamic
response at the point mass of a string was evaluated numerically. The possibility of reduction of a dynamic response
was found to depend on the location of a control force, the magnitude of a point mass and a forcing frequency
This talk is about the analysis of nonlinear energy harvesters. A particular example of an inverted beam harvester proposed by our group has been discussed in details.
Efficient mode-matching analysis of 2-D scattering by periodic array of circu...Yong Heui Cho
This document proposes a new mode-matching method for analyzing periodic arrays of circular cylinders with different materials. It uses a common-area concept and infinitesimal perfect magnetic conductor wires to match boundary conditions between rectangular and cylindrical coordinate systems. This allows derivation of scattering equations for the arrays. The solutions are compared to other results to validate the method. It can be used to study resonance characteristics of nanostructures and scattering behavior at different frequencies.
Fourier-transform analysis of a ridge waveguide and a rectangular coaxial lineYong Heui Cho
This document presents a new technique for analyzing ridge waveguides and rectangular coaxial lines using Fourier transforms. It transforms the structures into equivalent periodic transmission lines using image theory. It represents the fields using Fourier transforms and derives dispersion relations in rigorous yet simple series forms. Numerical results show fast convergence that agrees with other methods. The technique is applicable to other shielded transmission line structures.
This document discusses vibration energy harvesting in uncertain environments. It begins with an introduction that describes piezoelectric vibration energy harvesting and the importance of considering uncertainty in both the input excitation and system parameters. It then presents single degree of freedom electromechanical models for linear and nonlinear energy harvesting systems. Optimal energy harvesting is analyzed for a linear system with a circuit without an inductor, where the mean harvested power is derived under Gaussian excitation.
The document discusses the concept of derivative as a rate of change. It defines the average rate of change and instantaneous rate of change over an interval and as the limit as the interval approaches zero respectively. It provides examples of calculating average and instantaneous rates of change from graphs and data tables.
The document discusses the concept of derivative as a rate of change and provides examples of how it can be used to analyze quantities that change with respect to other variables, such as position, velocity, cost, revenue, etc. It also discusses the difference between average and instantaneous rates of change. Several practice problems are provided relating to topics like rectilinear motion, fluid flow, population growth, and more.
Accelerating Dynamic Time Warping Subsequence Search with GPUDavide Nardone
Many time series data mining problems require
subsequence similarity search as a subroutine. While this can
be performed with any distance measure, and dozens of
distance measures have been proposed in the last decade, there
is increasing evidence that Dynamic Time Warping (DTW) is
the best measure across a wide range of domains. Given
DTW’s usefulness and ubiquity, there has been a large
community-wide effort to mitigate its relative lethargy.
Proposed speedup techniques include early abandoning
strategies, lower-bound based pruning, indexing and
embedding. In this work we argue that we are now close to
exhausting all possible speedup from software, and that we
must turn to hardware-based solutions if we are to tackle the
many problems that are currently untenable even with stateof-
the-art algorithms running on high-end desktops. With this
motivation, we investigate both GPU (Graphics Processing
Unit) and FPGA (Field Programmable Gate Array) based
acceleration of subsequence similarity search under the DTW
measure. As we shall show, our novel algorithms allow GPUs,
which are typically bundled with standard desktops, to achieve
two orders of magnitude speedup. For problem domains which
require even greater scale up, we show that FPGAs costing just
a few thousand dollars can be used to produce four orders of
magnitude speedup. We conduct detailed case studies on the
classification of astronomical observations and similarity
search in commercial agriculture, and demonstrate that our
ideas allow us to tackle problems that would be simply
untenable otherwise.
Blind separation of complex-valued satellite-AIS data for marine surveillance...IJECEIAES
In this paper, the problem of the blind separation of complex-valued Satellite-AIS data for marine surveillance is addressed. Due to the specific properties of the sources under consideration: they are cyclo-stationary signals with two close cyclic frequencies, we opt for spatial quadratic time-frequency domain methods. The use of an additional diversity, the time delay, is aimed at making it possible to undo the mixing of signals at the multi-sensor receiver. The suggested method involves three main stages. First, the spatial generalized mean Ambiguity function of the observations across the array is constructed. Second, in the Ambiguity plane, Delay-Doppler regions of high magnitude are determined and Delay-Doppler points of peaky values are selected. Third, the mixing matrix is estimated from these Delay-Doppler regions using our proposed non-unitary joint zero-(block) diagonalization algorithms as to perform separation.
Multiscale methods for next generation graphene based nanocomposites is proposed. This approach combines atomistic finite element method and classical continuum finite element method.
Eh4 energy harvesting due to random excitations and optimal designUniversity of Glasgow
This lecture is about vibration energy harvesting when both the excitation and the system have uncertainties. Two cases, namely, when the excitation is a random process and when the system parameters are described by random variables are described. Optimal design for both cases is discussed.
This document provides an introduction to fluid mechanics fundamentals, including:
- The four primary dimensions in fluid mechanics are mass, length, time, and force. All other variables can be expressed in terms of these.
- Liquids can be treated as incompressible for most fluid mechanics problems since pressure changes are typically not large enough to cause changes in density.
- Viscosity describes a fluid's resistance to shear forces or layer sliding, and can result in either laminar (smooth) flow or turbulent (chaotic) flow.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology
Dynamic stiffness and eigenvalues of nonlocal nano beams - new methods for dynamic analysis of nano-scale structures. This lecture gives a review and proposed new techniques.
1) The document discusses ground excited systems, where the dynamic equations of motion are derived based on the relative displacement of the structure with respect to the ground acceleration vector.
2) Modal superposition is applied to decompose the equations into uncoupled modal equations, which are then solved to obtain the system response in terms of maximum displacements, storey shears, moments and drifts.
3) Several modal combination rules are discussed to combine the individual modal responses, including SRSS, CQC and double sum methods.
Optimal Transport for a Computer Programmer's Point of ViewBruno Levy
This document summarizes optimal transport and provides an elementary introduction. It describes the optimal transport problem of finding a transport map that moves mass from one distribution to another while minimizing costs. This is relaxed using the Kantorovich formulation, which finds a transport plan rather than a map. Duality is also introduced, showing the equivalence between the primal problem of minimizing costs and the dual problem of maximizing a function. The relationship is explained using a discrete version of the transport problem.
Controlling of Depth of Dopant Diffusion Layer in a Material by Time Modulati...IJCI JOURNAL
In this paper as a development of recently introduced analytical approach for estimation of temporal characteristics of mass and heat transport we present analysis of diffusion depth of dopant in a material with time varying diffusion coefficient. It has been shown, that changing of time dependence of diffusion coefficient gives a possibility to accelerate or decelerate diffusion process. In this situation it is an actual question is control of diffusion depth during manufacturing p-n-junctions. The controlling gives a possibility to obtain required depth of the junctions, but not larger or smaller.
Theoretical and Applied Phase-Field: Glimpses of the activities in IndiaDaniel Wheeler
1. The document summarizes recent work on phase-field modeling from several research groups in India.
2. It describes applications of phase-field modeling to spinodal decomposition, grain growth, precipitate evolution, and multi-phase solidification.
3. It highlights a recent study by the author using phase-field modeling to predict the equilibrium shapes of coherent precipitates under the influence of elastic stresses. The model accounts for elastic anisotropy and different eigenstrain configurations.
This document discusses information theory and related concepts such as entropy, Kullback-Leibler divergence, mutual information, independent component analysis, clustering algorithms, change point detection, kernel density estimation, and nonparametric regression. It provides mathematical definitions and formulas for these concepts. Figures are included to illustrate clustering and change point detection methods. The document contains information that could be useful for understanding techniques in machine learning, signal processing, and statistics.
This document discusses methods for identifying the source node of information spread in networks based on the observed spread over time. It begins by introducing epidemic models like SIS and SI for modeling information spread over networks. It then discusses maximum likelihood methods for identifying the source node on regular tree networks based on the observed subgraph. The accuracy of these methods increases with network size and degree. Extensions to other network structures and SIR models are also proposed. Overall, the document reviews mathematical models and algorithms for source identification in networks from limited observations of information spread.
This document summarizes a presentation on rigorously verifying the accuracy of numerical solutions to semi-linear parabolic partial differential equations using analytic semigroups. It introduces the considered problem of finding the solution to a semi-linear parabolic PDE. It then discusses using a piecewise linear finite element discretization in space and time to obtain an initial numerical solution. The goal is to rigorously enclose the true solution within a radius ρ of this numerical solution in the function space L∞(J;H10(Ω)). Key steps involve using properties of the analytic semigroup generated by the operator A and estimating discretization errors to compute the enclosure radius ρ.
This document presents an overview of optimization algorithms on Riemannian manifolds. It begins by introducing concepts such as vector transport and retraction mappings that are used to generalize algorithms from Euclidean spaces to manifolds. It then summarizes several classical optimization methods including gradient descent, conjugate gradient, and variants of quasi-Newton methods adapted to the Riemannian setting using these geometric concepts. The convergence of the Fletcher-Reeves method is analyzed under standard assumptions on the objective function. Overall, the document provides a conceptual and mathematical foundation for optimization on manifolds.
The document discusses the concept of derivative as a rate of change and provides examples of how it can be used to analyze quantities that change with respect to other variables, such as position, velocity, cost, revenue, etc. It also discusses the difference between average and instantaneous rates of change. Several practice problems are provided relating to topics like rectilinear motion, fluid flow, population growth, and more.
Accelerating Dynamic Time Warping Subsequence Search with GPUDavide Nardone
Many time series data mining problems require
subsequence similarity search as a subroutine. While this can
be performed with any distance measure, and dozens of
distance measures have been proposed in the last decade, there
is increasing evidence that Dynamic Time Warping (DTW) is
the best measure across a wide range of domains. Given
DTW’s usefulness and ubiquity, there has been a large
community-wide effort to mitigate its relative lethargy.
Proposed speedup techniques include early abandoning
strategies, lower-bound based pruning, indexing and
embedding. In this work we argue that we are now close to
exhausting all possible speedup from software, and that we
must turn to hardware-based solutions if we are to tackle the
many problems that are currently untenable even with stateof-
the-art algorithms running on high-end desktops. With this
motivation, we investigate both GPU (Graphics Processing
Unit) and FPGA (Field Programmable Gate Array) based
acceleration of subsequence similarity search under the DTW
measure. As we shall show, our novel algorithms allow GPUs,
which are typically bundled with standard desktops, to achieve
two orders of magnitude speedup. For problem domains which
require even greater scale up, we show that FPGAs costing just
a few thousand dollars can be used to produce four orders of
magnitude speedup. We conduct detailed case studies on the
classification of astronomical observations and similarity
search in commercial agriculture, and demonstrate that our
ideas allow us to tackle problems that would be simply
untenable otherwise.
Blind separation of complex-valued satellite-AIS data for marine surveillance...IJECEIAES
In this paper, the problem of the blind separation of complex-valued Satellite-AIS data for marine surveillance is addressed. Due to the specific properties of the sources under consideration: they are cyclo-stationary signals with two close cyclic frequencies, we opt for spatial quadratic time-frequency domain methods. The use of an additional diversity, the time delay, is aimed at making it possible to undo the mixing of signals at the multi-sensor receiver. The suggested method involves three main stages. First, the spatial generalized mean Ambiguity function of the observations across the array is constructed. Second, in the Ambiguity plane, Delay-Doppler regions of high magnitude are determined and Delay-Doppler points of peaky values are selected. Third, the mixing matrix is estimated from these Delay-Doppler regions using our proposed non-unitary joint zero-(block) diagonalization algorithms as to perform separation.
Multiscale methods for next generation graphene based nanocomposites is proposed. This approach combines atomistic finite element method and classical continuum finite element method.
Eh4 energy harvesting due to random excitations and optimal designUniversity of Glasgow
This lecture is about vibration energy harvesting when both the excitation and the system have uncertainties. Two cases, namely, when the excitation is a random process and when the system parameters are described by random variables are described. Optimal design for both cases is discussed.
This document provides an introduction to fluid mechanics fundamentals, including:
- The four primary dimensions in fluid mechanics are mass, length, time, and force. All other variables can be expressed in terms of these.
- Liquids can be treated as incompressible for most fluid mechanics problems since pressure changes are typically not large enough to cause changes in density.
- Viscosity describes a fluid's resistance to shear forces or layer sliding, and can result in either laminar (smooth) flow or turbulent (chaotic) flow.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology
Dynamic stiffness and eigenvalues of nonlocal nano beams - new methods for dynamic analysis of nano-scale structures. This lecture gives a review and proposed new techniques.
1) The document discusses ground excited systems, where the dynamic equations of motion are derived based on the relative displacement of the structure with respect to the ground acceleration vector.
2) Modal superposition is applied to decompose the equations into uncoupled modal equations, which are then solved to obtain the system response in terms of maximum displacements, storey shears, moments and drifts.
3) Several modal combination rules are discussed to combine the individual modal responses, including SRSS, CQC and double sum methods.
Optimal Transport for a Computer Programmer's Point of ViewBruno Levy
This document summarizes optimal transport and provides an elementary introduction. It describes the optimal transport problem of finding a transport map that moves mass from one distribution to another while minimizing costs. This is relaxed using the Kantorovich formulation, which finds a transport plan rather than a map. Duality is also introduced, showing the equivalence between the primal problem of minimizing costs and the dual problem of maximizing a function. The relationship is explained using a discrete version of the transport problem.
Controlling of Depth of Dopant Diffusion Layer in a Material by Time Modulati...IJCI JOURNAL
In this paper as a development of recently introduced analytical approach for estimation of temporal characteristics of mass and heat transport we present analysis of diffusion depth of dopant in a material with time varying diffusion coefficient. It has been shown, that changing of time dependence of diffusion coefficient gives a possibility to accelerate or decelerate diffusion process. In this situation it is an actual question is control of diffusion depth during manufacturing p-n-junctions. The controlling gives a possibility to obtain required depth of the junctions, but not larger or smaller.
Theoretical and Applied Phase-Field: Glimpses of the activities in IndiaDaniel Wheeler
1. The document summarizes recent work on phase-field modeling from several research groups in India.
2. It describes applications of phase-field modeling to spinodal decomposition, grain growth, precipitate evolution, and multi-phase solidification.
3. It highlights a recent study by the author using phase-field modeling to predict the equilibrium shapes of coherent precipitates under the influence of elastic stresses. The model accounts for elastic anisotropy and different eigenstrain configurations.
This document discusses information theory and related concepts such as entropy, Kullback-Leibler divergence, mutual information, independent component analysis, clustering algorithms, change point detection, kernel density estimation, and nonparametric regression. It provides mathematical definitions and formulas for these concepts. Figures are included to illustrate clustering and change point detection methods. The document contains information that could be useful for understanding techniques in machine learning, signal processing, and statistics.
This document discusses methods for identifying the source node of information spread in networks based on the observed spread over time. It begins by introducing epidemic models like SIS and SI for modeling information spread over networks. It then discusses maximum likelihood methods for identifying the source node on regular tree networks based on the observed subgraph. The accuracy of these methods increases with network size and degree. Extensions to other network structures and SIR models are also proposed. Overall, the document reviews mathematical models and algorithms for source identification in networks from limited observations of information spread.
This document summarizes a presentation on rigorously verifying the accuracy of numerical solutions to semi-linear parabolic partial differential equations using analytic semigroups. It introduces the considered problem of finding the solution to a semi-linear parabolic PDE. It then discusses using a piecewise linear finite element discretization in space and time to obtain an initial numerical solution. The goal is to rigorously enclose the true solution within a radius ρ of this numerical solution in the function space L∞(J;H10(Ω)). Key steps involve using properties of the analytic semigroup generated by the operator A and estimating discretization errors to compute the enclosure radius ρ.
This document presents an overview of optimization algorithms on Riemannian manifolds. It begins by introducing concepts such as vector transport and retraction mappings that are used to generalize algorithms from Euclidean spaces to manifolds. It then summarizes several classical optimization methods including gradient descent, conjugate gradient, and variants of quasi-Newton methods adapted to the Riemannian setting using these geometric concepts. The convergence of the Fletcher-Reeves method is analyzed under standard assumptions on the objective function. Overall, the document provides a conceptual and mathematical foundation for optimization on manifolds.
The SlideShare 101 is a quick start guide if you want to walk through the main features that the platform offers. This will keep getting updated as new features are launched.
The SlideShare 101 replaces the earlier "SlideShare Quick Tour".
This document describes research on modeling and optimizing the dynamics and gait of multi-link swimming robots using a "perfect fluid" model. The researchers formulated the dynamics of an articulated multi-link swimming robot moving in a planar environment. They reduced the system to first-order equations and developed simulations to examine performance for harmonic inputs and optimize displacement through inputs. Experiments were also planned using prototype robotic swimmers to compare with the theoretical model.
To compare different turbulence models for the simulation of the flow over NA...Kirtan Gohel
The document describes a project to compare different turbulence models for simulating flow over a NACA0015 airfoil. The objective is to determine the most suitable turbulence model. Three models will be compared - k-omega SST, k-epsilon standard, and k-kl-omega. Flow over the airfoil will be simulated at different angles of attack using ANSYS Fluent. Lift and drag coefficients will be observed and compared to experimental data to evaluate which model most accurately captures the airfoil's performance.
In this study the kinematic wave equation has been solved numerically using the modified Lax
explicit finite difference scheme (MLEFDS) and used for flood routing in a wide prismatic channel and a nonprismatic
channel. Two flood waves, one sinusoidal wave and one exponential wave, have been imposed at the
upstream boundary of the channel in which the flow is initially uniform. Six different schemes have been
introduced and used to compute the routing parameter, the wave celerity c. Two of these schemes are based on
constant depth and use constant celerity throughout the computation process. The rest of the schemes are based
on local depths and give celerity dependent on time and space. The effects of the routing parameter c on the
travel time of flood wave, the subsidence of the flood peak and the conservation flood flow volume have been
studied. The results seem to indicate that there is a minimal loss/gain of flow volume whatever the scheme is.
While it is confirmed that neither of the schemes is 100% volume conservative, it is found that the scheme
Kinematic Wave Model-2 (KWM-II) gives the most accurate result giving only 0.1% error in perspective of
volume conservation. The results obtained in this study are in good qualitative agreement with those obtained in
other similar studies.
The document summarizes a study of the near-contact-line dynamics of evaporating sessile drops containing bacteria. As the drop evaporates, an internal flow develops that transports bacteria outward and concentrates them near the contact line, where experiments show they form periodic jets. The study develops a theoretical model and numerical simulation of the averaged flow properties and bacteria behavior. Initial 1D simulations show bacteria transitioning from isotropic to aligned with flow near the edge, and bacteria density peaking near the edge matching experiments. Future 2D simulations aim to reproduce the periodic jet pattern observed.
The document summarizes an experimental and theoretical study of a mechanical system consisting of a sliding car that bounces on an oscillating piston. The researchers were able to produce period-1, period-2, period-3 orbits, sticking solutions, and chaotic behaviors experimentally that agreed well with the theoretical model. They aim to identify parameters that produce different orbit types and find co-existing orbits by varying the piston frequency and amplitude. The experimental setup uses infrared lights and a Nintendo Wii remote to track the car's position over time.
First and second order semi-Markov chains for wind speed modelingNozir Shokirov
An overview of Guglelmo D'Amic et al. paper titled as "First and second order semi-Markov chains for wind speed modeling" from the journal of Physica A 2012.
Compit 2013 - Torsional Vibrations under Ice ImpactSimulationX
- The document discusses bridging the gap between steady-state and transient simulation for torsional vibrations under ice impact.
- It introduces modeling methods that allow both transient and steady-state analysis to operate on the same model base using a unified framework based on ordinary differential equations.
- It also discusses propeller modeling that incorporates established steady-state and transient methods and is being certified by classification societies for compliance with ice class simulation requirements.
Theories and Applications of Spatial-Temporal Data Mining and Knowledge Disco...Beniamino Murgante
This document summarizes spatial-temporal data mining and knowledge discovery techniques. It discusses (1) clustering spatial data using scale-space filtering and regression-classification decomposition, (2) classifying spatial data using neural networks and decision trees, (3) discovering temporal processes using multifractal analysis, and (4) uncovering knowledge structures from relational spatial data using concept lattices. Various applications are described, including clustering typhoon tracks, earthquake data, and daily rainfall patterns to identify spatial and temporal patterns.
This document describes a numerical simulation of the dynamics of a tethered buoy system. It proposes a novel mixed finite element formulation to model the elastic cable in a robust way, even when the Young's modulus is very large. It also uses quaternion variables to describe the floating body's dynamics, providing numerical stability during large rotations. The coupled nonlinear equations governing the cable and body are discretized in time using the implicit Backward Euler method and linearized with a damped Newton's method. Validation simulations are presented to demonstrate the accuracy and robustness of the overall numerical procedure.
Lattice boltzmann simulation of non newtonian fluid flow in a lid driven cavitIAEME Publication
This document summarizes a study that uses Lattice Boltzmann Method (LBM) to simulate non-Newtonian fluid flow in a lid driven cavity. The study explores the mechanism of non-Newtonian fluid flow using the power law model to represent shear-thinning and shear-thickening fluids. It investigates the influence of power law index and Reynolds number on velocity profiles and streamlines. The LBM code is validated against published results and shows agreement with established theory and fluid rheological behavior.
This document summarizes large eddy simulations of supersonic non-reactive and reactive flows performed with an immersed boundary method on two configurations. The first test case is a Mach 3.5 flow over a cylinder, which showed excellent agreement with theory. The second case is a supersonic hydrogen-air burner, where comparisons to experimental data for species mass fractions and temperature also led to good agreement. The impact of burner geometry on the velocity and species fields was studied using the immersed boundary method.
This document summarizes an experimental, numerical, and theoretical analysis of supersonic flow over a solid diamond wedge. The study examines boundary layer shockwave effects and pressure coefficients (Cp) for supersonic flow past the wedge. Experimental data is collected from a wind tunnel test using a diamond wedge model. Pressure readings are recorded for various angles of attack and used to calculate Cp. The experimental results are compared to theoretical analyses using Ackeret's linear theory and computational fluid dynamics simulations. Limitations of each method are discussed along with discrepancies between experimental and theoretical results.
1. The fundamental forces of nature are arranged in increasing strength as: gravitational force < weak nuclear forces < electromagnetic forces < strong nuclear forces.
2. The coefficient of friction does not change with weight of the body, as it depends on the nature of the surfaces, not the weight.
3. The gravitational field inside a solid sphere varies directly as the distance (x) from the centre if x < R, and inversely as x if x > R, where R is the radius of the sphere.
1. The document numerically investigates turbulent air flow in a coaxial jet burner using Reynolds Averaged Navier Stokes (RANS) modeling.
2. It compares predicted results of air axial velocity, air swirl velocity, and turbulent kinetic energy at different axial positions to experimental measurements from a previous study.
3. The simulation results show good agreement with experimental data, except at side regions where air velocity is under estimated, demonstrating RANS is a reasonably accurate approach for modeling industrial turbulent flows.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Lid driven cavity flow simulation using CFD & MATLABIJSRD
Steady Incompressible Navier-Stokes equation on a uniform grid has been studied at various Reynolds number using CFD (Computational Fluid Dynamics). Present paper aim is to obtain the stream-function and velocity field in steady state using the finite difference formulation on momentum equations and continuity equation. Reynold number dominates the flow problem. Taylor’s series expansion has been used to convert the governing equations in the algebraic form using finite difference schemes. MATLAB has been used to draw to flow simulations inside the driven-cavity.
Flow Inside a Pipe with Fluent Modelling Andi Firdaus
This document describes a numerical simulation of laminar and turbulent flow inside a pipe using Fluent software. The simulation models water flow inside a 1m diameter pipe that is 20m long. Two models are considered: laminar flow at a Reynolds number of 300 and turbulent flow at 8500. Theoretical equations for laminar and turbulent velocity profiles, entrance length, and Reynolds number correlations are presented. The numerical simulation sets up the models with appropriate boundary and material properties to solve the steady-state Navier-Stokes equations and compare results to experimental data.
This document discusses global stability analysis of three-dimensional flows. It begins by introducing hydrodynamic instabilities and how they are studied using both local and global stability analysis. The objectives of the author's PhD research are then stated as extending global stability tools to fully three-dimensional flows and analyzing transition induced by surface roughness. Selective frequency damping is described as the technique used to compute base flows. The document outlines the theory and numerical methods behind global stability analysis of three-dimensional perturbations on a given base flow.
Literature survey modeling of microfluidics devicesAweshkumarsingh
This presentation discusses modeling of microfluidics devices. It begins with definitions of electrokinetics phenomena like electroosmosis, electrophoresis, and dielectrophoresis that are important in microfluidics. It then discusses various modeling approaches like continuum models using Navier-Stokes equations, molecular dynamics simulations, DSMC, and lattice Boltzmann methods. Examples of applying these methods to study phenomena like mixing and particle separation in microchannels are provided.
- Hiroaki Shiokawa's research interests include graph mining, network analysis, and efficient algorithms. He was previously employed at NTT from 2011 to 2015.
- His current research focuses on developing clustering algorithms for large-scale networks and evaluating their performance on real-world network datasets.
- He has published highly cited papers in top data mining and network science conferences such as KDD, CIKM, and WSDM.
Mechanics:- Simple and Compound PendulumPravinHudge1
a compound pendulum is a physical system with a more complex structure than a simple pendulum, incorporating its mass distribution and dimensions into its oscillatory motion around a fixed axis. Understanding its dynamics involves principles of rotational mechanics and the interplay between gravitational potential energy and kinetic energy. Compound pendulums are used in various scientific and engineering applications, such as seismology for measuring earthquakes, in clocks to maintain accurate timekeeping, and in mechanical systems to study oscillatory motion dynamics.
TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptxshubhijain836
Centrifugation is a powerful technique used in laboratories to separate components of a heterogeneous mixture based on their density. This process utilizes centrifugal force to rapidly spin samples, causing denser particles to migrate outward more quickly than lighter ones. As a result, distinct layers form within the sample tube, allowing for easy isolation and purification of target substances.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
Evaluation and Identification of J'BaFofi the Giant Spider of Congo and Moke...MrSproy
ABSTRACT
The J'BaFofi, or "Giant Spider," is a mainly legendary arachnid by reportedly inhabiting the dense rain forests of
the Congo. As despite numerous anecdotal accounts and cultural references, the scientific validation remains more elusive.
My study aims to proper evaluate the existence of the J'BaFofi through the analysis of historical reports,indigenous
testimonies and modern exploration efforts.
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆Sérgio Sacani
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ∼ 106M⊙ black hole (BH) that is currently in the process of ‘turning on’. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1−W2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ∼ 3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 106M⊙ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: active– accretion, accretion discs– galaxies: individual: SDSS J133519.91+072807.4
Signatures of wave erosion in Titan’s coastsSérgio Sacani
The shorelines of Titan’s hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it isunclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theo-retical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion,but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titanremain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively dis-cern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combinelandscape evolution models with measurements of shoreline shape on Earth to characterize how differentcoastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that theshorelines of Titan’s seas are most consistent with flooded landscapes that subsequently have been eroded bywaves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates atfetch lengths of tens of kilometers.
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Hariyalikart Case Study of helping farmers in Biharrajsaurav589
Helping farmers all across India through our latest technologies of modern farming like drones for irrigation and best pest control For more visit : https://www.hariyalikart.com/case-study
6. 6
The importance (2)
Crowd
dynamics
contributes
to
social
safety
(dys)func-on
of
collec-ve
mo-on
control
-‐
avoid
crowd
disasters
-‐
flow
op-miza-on
-‐
efficient
transporta-on
7. 7
The importance (3)
-‐
Crowd
mo-on
has
par-cle-‐scale
instability.
-‐
Crowd
system
refuse
the
con-nuous
approxima-on.
-‐
Need
an
alterna-ve
descrip-on!
How
should
we
describe
and
understand
the
discrete
flow?
Fluid?
Par-cle?
16. 16
Lane formation: formulation
The
social
force
model
(Helbing2000)
periodic
the
self-‐driven
force
N=50
m=80
kg,
tau=0.5
s,
v0=1
m/s,
ri=0.3
m,
A=2000
N,
B=0.08
m,
15
m
5
m
the
two-‐body
interac-on
The
B.
C.
19. 19
Lane formation: properties
(1)
A
popular
collec-ve
phenomenon
-‐
possibility
(1974)
-‐
observa-on
and
simula-on
(1992)
(2)
Counter
driving
force
+
Social
repulsive
force
(3)
"par-cle-‐resolved
instability"
(4)
Universality
20. 20
Lane formation: similar phenomena
Granular
stra-fica-on
[新屋他,
JSSI
&
JSSE
Joint
Conference
(2012)]
[Dzubiella
et
al.,
PRE
65,
021402
(2002)]
colloid
[Makse
et
al.,
Nature
386,
27
(1997)]
Granular
Rayreigh-‐
Taylor
instability
Electric
field
sand
sand
g
g
25. 25
Freezing-‐‑‒by-‐‑‒heating: scenario
kine-c
energy
noise
intensity
freezing
laning
small
noise
-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐
bistable
intermediate
noise
-‐-‐-‐
laning
is
prohibited
large
noise
-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐
all
possible
states
break
up
28. 28
Oscillatory flow: history
-‐
numerically
found
Helbing
et
al.,
PRE
51,
4282
(1995)
-‐
experimentally
confirmed
Helbing
et
al.,
Transporta-on
sci.
39
1
(2005)
-‐
empirically
plausible
29. 29
Oscillatory flow
-‐
Numerically
iden-fied
as
the
Hopf
bifurca-on
(Corradi2012)
-‐
The
physical
mechanism
is
s-ll
unknown
-‐
A
similar
phenomenon:
saltwater
oscillator
(Yoshikawa1991)
bo6leneck
width
center
of
mass
water
saltwater
30. 30
Simulation: setup
Model:
the
SFM
B.C.
:
a
periodic
channel
45 m
5 m
w
4 m
Parameters:
N=150,
m=80
kg,
𝜏=0.5
s,
v0=1.0m/s
A=573
N,
B=0.08
m
31. 31
Simulation: results
The
-me
evolu-on
of
the
momentum
density
The
Fourier
amplitude
v.s.
bo6leneck
width
-me[s]
momentum
bo6leneck
width
[m]
amplitude
32. 32
Oscillatory flow: open questions
-‐
A
type
of
nonlinear
self-‐excitable
oscillator?
-‐
Mathema-cal
model?
-‐
The
rela-on
to
the
fluid
oscillator?
-‐
Synchroniza-on?
34. 34
the
microscopic
many-‐par-cle
model
(the
social
force
model,
SFM)
self-‐driven
force
repulsive
force
elas-c
force
fric-on
wall
exit
The faster-‐‑‒is-‐‑‒slower effect: detail
m
dvi (t)
dt
= fself + fij
j≠i
∑
35. 35
The faster-‐‑‒is-‐‑‒slower effect: detail
mechanism?
modeling!
driving force
driving force
driving force
Suzuno
et
al.,
Phys.
Rev.
E
88,
052813
(2013).
36. 36
We
just
consider
the
par-cle
near
the
exit
and
its
equa-on
of
mo-on.
N
Analy-c
expression
of
the
flow
velocity
The outline of the modeling
37. 37
-‐
the
eq.
of
mo-on
h
v0
kg(l)+Ae
κg(l)vr
-‐
balance
of
force
x
g(x)
We
focus
on
the
arch
forma-on
of
the
par-cles.
l
v0
Note:
dimensionless.
a
means
the
collision
effect.
[ ]
The model
Suzuno
et
al.,
Phys.
Rev.
E
88,
052813
(2013).
38. 38
(1)
The
discharge
property
is
determined
by
the
par-cles
in
the
vicinity
of
the
exit.
(2)
The
flow
has
radial
symmetry.
(3)
N
is
fixed.
(4)
The
flow
rate
is
propor-onal
to
the
velocity
of
the
model
par-cle.
(5)
The
parameters
sa-sfy
.
(This
means
that
fric-on
is
appropriately
large.)
N
The model assumptions
39. 39
Model
Sta-onary
situa-on
l
the
analy-cal
expression
of
the
velocity!
[ ]
The model analysis
40. 40
Our
model
reproduces
the
simula-on
results.
our
model
simula-on
The model results
"faster"
is
"slower"
Suzuno
et
al.,
Phys.
Rev.
E
88,
052813
(2013).
41. 41
1+g(v0) (contact
fric-on)
v0
(driving
force)
coupling
const.
of
the
social
force
linear
elas-city
faster-‐is-‐slower
ouulow
~
The
solu-on
has
the
form
The mechanism of the phenomenon
Suzuno
et
al.,
Phys.
Rev.
E
88,
052813
(2013).
42. 42
If
our
model
is
correct,
the
original
system
shows:
(a)
If
fric-on
is
linear,
then
no
"faster-‐".
(b)
If
no
fric-on,
then
no
"faster-‐".
Validation
linear
fric-on
no
fric-on
correct
predic-ons!
Suzuno
et
al.,
Phys.
Rev.
E
88,
052813
(2013).
43. 43
(1)
We
proposed
a
simplified
model
for
the
"faster-‐is-‐slower"
effect.
(2)
We
clarify
that
the
"faster-‐"
comes
from
the
compe--on
between
driving
force
and
nonlinear
fric-on.
(3)
This
work
gives
an
example
of
the
study
of
collec-ve
discrete
flow
via
mathema-cal
modeling.
Summary of "faster-‐‑‒is-‐‑‒slower"
44. 44
Summary of the talk
Crowd
dynamics
offers:
(i)
examples
of
spontaneous
pa6ern
forma-on
(ii)
insights
into
the
efficient
transporta-on
(iii)
mathema-cal
issues:
how
to
describe
the
mesoscale,
transient
and
discrete
flow?
45. 45
Critical discussion (1)
cri-cism
1.
How
do
you
believe
you
can
describe
mathema-cally
the
crowd
mo-on,
which
is
related
to
the
free
will?
cri-cism
2.
You
can
reproduce
any
results
from
simula-ons.
cri-cism
3.
Is
crowd
mo-on
the
result
of
self-‐organiza-on
truly?
46. 46
Critical discussion (2)
Mathema-cal
(physical)
studies
of
crowd
dynamics
only
hold
for:
(i)
panic
situa-ons,
(ii)
each
person
have
their
definite
des-na-ons
but
the
ways
to
reach
there
are
less
conscious,
(iii)
the
size
of
crowds
is
large,
that
is,
the
absence
of
sophis-cated
intelligent
ac-on.
47. Many
types
of
model
is
available:
To
avoid
the
arbitrariness
of
results,
we
should
take
the
following
steps:
(i)
assume
physically-‐acceptable
mechanisms,
(ii)
reproduce
the
phenomenon
by
minimal
models,
and
(iii)
iden-fy
the
necessary
condi-on.
47
Critical discussion (3)
circle
ellip-c
non-‐spherical
48. rather
social
48
Critical discussion (4)
The
concept
of
self-‐organiza-on
is
NOT
omnipotent
rather
physical
-‐
Crowd
mo-on
includes
social
factors.
-‐
We
have
to
no-ce
that
all
crowd
mo-on
should
not
be
reduced
to
Mathema-cal
models.