This document summarizes research on modeling swimming microorganisms using theories of nematic liquid crystals. It discusses how flocking behavior can emerge from simple interaction rules and similarities to liquid crystal models. The document then analyzes a simplified 1D active nematic model to explore spontaneous flow, flow induced by shear, and backflow coupling. It finds different stable states can form depending on the activity parameter and initial conditions. Finally, it poses questions about including additional factors like density and polar order, using continuum models for large organisms, and effects on mixing.
FERROMAGNETIC-FERROELECTRIC COMPOSITE 1D NANOSTRUCTURE IN THE PURSUIT OF MAGN...ijrap
Nanocomposites of linear chain of ferroelectric-ferromagnetic crystal structure is considered. It is analyzed
theoretically in the motion equation method on the pursuit of magnonic excitations,lattice vibration
excitations and their interactions leading to a new collective mode of excitations,the electormagnons. In
this particular work, it is observed that the magnetizations and polarizations are tunable in a given temperature ranges for some specific values of the coupling order parameter.
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FERROMAGNETIC-FERROELECTRIC COMPOSITE 1D NANOSTRUCTURE IN THE PURSUIT OF MAGN...ijrap
Nanocomposites of linear chain of ferroelectric-ferromagnetic crystal structure is considered. It is analyzed
theoretically in the motion equation method on the pursuit of magnonic excitations,lattice vibration
excitations and their interactions leading to a new collective mode of excitations,the electormagnons. In
this particular work, it is observed that the magnetizations and polarizations are tunable in a given temperature ranges for some specific values of the coupling order parameter.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Presentation for my students about basics of making a good research talk (In Polish).
Prezentacja dla moich studentów o podstawach robienia dobrej prezentacji naukowej (po polsku).
The outstanding properties of metamaterials open the door of opportunity for a number of exciting practical applications. Fascinating applications such as: perfect lenses that break the diffraction limit of conventional lenses, optical quantum storage, and invisibility cloaking.
BioHarm - poprawia system komunikacji międzykomórkowej, Można skutecznie wykorzystywać do wzmocnienia procesów adaptacyjnych organizmu, zwłaszcza do ochrony przed szkodliwymi czynnikami – stresem, zanieczyszczeniem środowiska – na które jesteśmy narażeni każdego dnia.
DPS material
DNG material ( Do not depend on the chemical composition, Depend on the geometry of the structure units, Metamaterials are artificial engineered composite structures, Not commonly found in nature)
MNG material
ENG material
Organic chemistry has two main divisions. One division deals with aliphatic (fatty) compounds, the first compounds you encountered in Organic Chemistry I. The second division includes the aromatic (fragrant) compounds, of which benzene is a typical example
Presentation for my students about basics of making a good research talk (In Polish).
Prezentacja dla moich studentów o podstawach robienia dobrej prezentacji naukowej (po polsku).
The outstanding properties of metamaterials open the door of opportunity for a number of exciting practical applications. Fascinating applications such as: perfect lenses that break the diffraction limit of conventional lenses, optical quantum storage, and invisibility cloaking.
BioHarm - poprawia system komunikacji międzykomórkowej, Można skutecznie wykorzystywać do wzmocnienia procesów adaptacyjnych organizmu, zwłaszcza do ochrony przed szkodliwymi czynnikami – stresem, zanieczyszczeniem środowiska – na które jesteśmy narażeni każdego dnia.
DPS material
DNG material ( Do not depend on the chemical composition, Depend on the geometry of the structure units, Metamaterials are artificial engineered composite structures, Not commonly found in nature)
MNG material
ENG material
Organic chemistry has two main divisions. One division deals with aliphatic (fatty) compounds, the first compounds you encountered in Organic Chemistry I. The second division includes the aromatic (fragrant) compounds, of which benzene is a typical example
Uma questão fundamental na astrobiologia, é: se a vida pode ser transportada entre planetas extrassolares, e sistemas planetários? Uma equipe de astrofísicos norte-americanos propôs uma nova estratégia para responder a essa questão com base no princípio que a vida alienígena que surgiu via espalhamento – num processo chamado de panspermia – exibirá mais aglomerados do que a vida que surge espontaneamente.
Existem duas maneiras básicas para a vida ter se espalhado além de sua estrela hospedeira.
A primeira seria por meio de um processo natural de arremessamento de asteroides e cometas. A segunda seria por meio da vida inteligente que deliberadamente viajaria pelo espaço.
Um novo artigo, aceito para publicação no Astrophysical Journal Letters, não lida como a panspermia ocorre. Ele simplesmente pergunta: se ela ocorreu, nós poderíamos detectá-la? Em princípio, a resposta é sim.
O modelo desenvolvido pela equipe no Harvard-Smithsonian Center for Astrophysics assume que as sementes de um planeta vivo se espalham em todas as direções.
This presentation gives a brief introduction to the concept of coupled CFD-DEM Modeling.
Link to file: https://drive.google.com/open?id=1nO2n49BwhzBtT6NnvpxADG5WsC9uMJ-i
Visual Analysis of Non Linear Systems, Chaos, Fractals, Self Similarity
Please subscribe to my YouTube Channel for best training lectures:
https://www.youtube.com/channel/UCRkUJFOsyZG1E1LDWzUr_hw
Introduction to Classical Mechanics:
UNIT-I : Elementary survey of Classical Mechanics: Newtonian mechanics for single particle and system of particles, Types of the forces and the single particle system examples, Limitation of Newton’s program, conservation laws viz Linear momentum, Angular Momentum & Total Energy, work-energy theorem; open systems (with variable mass). Principle of Virtual work, D’Alembert’s principle’ applications.
UNIT-II : Constraints; Definition, Types, cause & effects, Need, Justification for realizing constraints on the system
LECTURE 1 PHY5521 Classical Mechanics Honour to Masters LevelDavidTinarwo1
Classical mechanics, a well-organized introductory lecture. This is easy to follow, and a must-go-through lecture. UNIT-I : Elementary survey of Classical Mechanics: Newtonian mechanics for single particle and system of particles, Types of the forces and the single particle system examples, Limitation of Newton’s program, conservation laws viz Linear momentum, Angular Momentum & Total Energy, work-energy theorem; open systems (with variable mass). Principle of Virtual work, D’Alembert’s principle’ applications.
UNIT-II : Constraints; Definition, Types, cause & effects, Need, Justification for realizing constraints on the system, Difficulties introduced by imposing constraints on the system, Examples of constraints, Introduction of generalized coordinates justification. Lagrange’s equations; Linear generalized potentials, Generalized coordinates and momenta & energy; Gauge function for Lagrangian and its gauge invariance, Applications to constrained systems and generalized forces.
Theory of Vibrations: Introduction to the theory of vibrations in multi-degree-of-freedom systems, Normal modes and modal analysis, Nonlinear oscillations and chaos theory.
Canonical Transformations: Properties and classification of canonical transformations, Action-angle variables and their applications in integrable systems, Canonical perturbation theory and perturbation methods.
Poisson's and Lagrange's Brackets: Definitions and properties of Poisson's brackets, Relationship between Poisson's brackets and Hamilton's equations, Lagrange's brackets and their applications in dynamics. UNIT-III : Cyclic coordinates, Integrals of the motion, Concepts of symmetry, homogeneity and isotropy, Invariance under Galilean transformations Hamilton’s equation of motion: Legendre’s dual transformation, Principle of least action; derivation of equations of motion; variation and end points; Hamilton’s principle and characteristic functions; Hamilton-Jacobi equation.
UNIT-IV : Central force fields: Definition and properties, Two-body central force problem, gravitational and electrostatic potentials in central force fields, closure and stability of circular orbits; general analysis of orbits; Kepler’s laws and equation, Classification of orbits, orbital dynamics and celestial mechanics, differential equation of orbit, Virial Theorem.
UNIT-V : Canonical transformation; generating functions; Properties; group property; examples; infinitesimal generators; Poisson bracket; Poisson theorems; angular momentum PBs; Transition from discrete to continuous system, small oscillations (longitudinal oscillations in elastic rod); normal modes and coordinates.
What does it mean for something to be a dynamical system What is .pdfvikasbajajhissar
What does it mean for something to be a \"dynamical system? What is a \"dynamical equation?
What does it mean if a system is \" sensitive to initial conditions\"? Give one example of a
dynamical system that has been shown to be sensitive to initial conditions.
Solution
Dynamical systems theory is an area of mathematics used to describe the behavior of complex
dynamical systems, usually by employing differential equations or difference equations.
Dynamical systems are mathematical objects used to model physical phenomena whose state
(or instantaneous description) changes over time. These models are used in financial and
economic forecasting, environmental modeling, medical diagnosis, industrial equipment
diagnosis, and a host of other applications.
So a simple, if slightly imprecise, way of describing chaos is \"chaotic systems are
distinguished by sensitive dependence on initial conditions and by having evolution through
phase space that appears to be quite random.\"
In particular, a chaotic dynamical system is generally characterized by
1. Having a dense collection of points with periodic orbits,
2. Being sensitive to the initial condition of the system (so that initially nearby points can evolve
quickly into very different states), a property sometimes known as the butterfly effect, and
3. Being topologically transitive.
Dynamical systems theory is an area of mathematics used to describe the behavior of complex
dynamical systems, usually by employing differential equations or difference equations.
Dynamical systems are mathematical objects used to model physical phenomena whose state
(or instantaneous description) changes over time. These models are used in financial and
economic forecasting, environmental modeling, medical diagnosis, industrial equipment
diagnosis, and a host of other applications.
So a simple, if slightly imprecise, way of describing chaos is \"chaotic systems are
distinguished by sensitive dependence on initial conditions and by having evolution through
phase space that appears to be quite random.\"
In particular, a chaotic dynamical system is generally characterized by
1. Having a dense collection of points with periodic orbits,
2. Being sensitive to the initial condition of the system (so that initially nearby points can evolve
quickly into very different states), a property sometimes known as the butterfly effect, and
3. Being topologically transitive..
The Monte Carlo Method of Random Sampling in Statistical PhysicsIOSR Journals
The Monte Carlo technique of random sampling was reviewed in this work. It plays an important role in Statistical Mechanics as well as in scientific computation especially when problems have a vast phase space. The purpose of this paper is to review a general method, suitable to fast electronic computing machines, for calculating the properties of any system which may be considered as composed of interacting particles. Concepts such as phase transition, the Ising model,ergodicity, simple sampling, Metropolis algorithm, quantum Monte Carlo and Non-Boltzmann sampling were discussed. The applications of Monte Carlo method in other areas of study aside Statistical Physics werealso mentioned.
Physics Project On Physical World, Units and MeasurementSamiran Ghosh
This PowerPoint is Physical World, Units and Measurement. This is basically the first chapter of 11th class/grade. This power point explains the basic or fundamental physics with some information about SI units and fundamental forces.
Similar to Using a theory of nematic liquid crystals to model swimming microorganisms (20)
Physics Project On Physical World, Units and Measurement
Using a theory of nematic liquid crystals to model swimming microorganisms
1. Using a theory of nematic
liquid crystals to model
swimming microorganisms
Nigel Mottram
Department of Mathematics and Statistics
University of Strathclyde
2. Background
Swimming organisms, motivation:
Behaviour of fish, sea mammals, interaction with man-
made objects
Smaller organisms, zooplankton, phytoplankton
Interesting self-organisation
Non-equilibrium fluid dynamics
6. Self-organisation
Flocking/shoaling:
A mathematical model considers "flocking" as the collective motion of a
large number of self-propelled entities.
It is considered an emergent behaviour arising from simple rules that are
followed by individuals and does not involve any central coordination.
7. Flocking
The first model of flocking involved three relatively simple rules
Separation - avoid crowding neighbours (short range repulsion)
Alignment - steer towards average heading of neighbours
Cohesion - steer towards average position of neighbours (long range
attraction)
A simpler model changes the direction of motion by averaging over
neighbours
is the average orientation of neighbours, is a random
fluctuation
8. Flocking
(a) High noise, low density: particles move independently
(b) Low noise, low density: particles form independent groups
(c) High noise, high density: particles move with some correlation
(d) Low noise, high density: all particles move in same direction
9. Flocking and Ferromagnetism?
The part of this update rule looks like a model of a ferromagnet…
…but in a ferromagnet you can’t have a symmetry breaking event in 2d
The flocking model creates organisation because it is out of equilibrium.
10. Similarities to liquid crystal molecular dynamics
The Gay-Berne potential is used to model a group of elongated
molecules…
11. Similarities to liquid crystal molecular dynamics
Separation – repulsion as molecules approach
Alignment – side-side alignment gives lower energy state
Cohesion – presence of a minimum in the energy
13. Coarsening – continuum limit
We move to a continuum model by thinking of the velocity at a point in
space as being the average velocity of a (large) number of entities.
Possibly more plausible for microorganisms but has been used for
larger organisms.
Governing equations are derived in a similar way to the Navier-Stokes
but without the Galilean invariance.
We should probably also model the orientational order of the entities
14. A simpler model
A simpler model has been proposed, which does include orientational order.
In this model the “swimming” organisms are either “pushers” or “pullers”
extensile (pushers) contractile (pullers)
An appropriate model is the Ericksen-Leslie with an extra term in the stress
tensor
We will consider a simple 1d system to look at the basic properties of an
active nematic
We look at three cases: (a) Spontaneous flow, (b) Flow induced through
shear, (c) Backflow and kickback
15. Spontaneous flow
The active nematic is initially aligned
parallel to the bounding surfaces.
Flow is only considered in one direction and
the director stays in the plane.
What happens?
The active nematic induces flow but if is
constant there will be no contribution to the
flow equation.
Will the system break the symmetry and create flow?
17. Spontaneous flow
Apply the boundary condition for ,
then using the equation for the velocity and the boundary condition…
we arrive at the following condition
18. Spontaneous flow
This condition determines when the initial state becomes unstable
This indicates that, for sufficiently
small values of , the mode decays,
leaving the initial state.
However, for a mode
becomes unstable.
This plot also indicates other
unstable modes and other critical
values of the activity parameter.
19. Spontaneous flow
We can see this instability by solving the full nonlinear equations for
different values of and for different initial conditions.
For the initial state decays.
22. Spontaneous flow
We find at least three solutions, two of which seem to be (locally) stable.
For higher values of the activity parameter we would expect even more
possible solutions. Further analysis of the bifurcations and solution
stabilities is needed.
We would like to be able to find critical values of ζ for which different
solutions exist.
23. Alignment in shear flow
If we now force a shear in the system
there is no stable trivial state and the
director prefers to align at the “flow-
aligning” angle.
There are however, instabilities away
from this state.
This system might be similar to a layer
of active nematic on top of a moving
immiscible fluid.
The induced flow from the active
nematic may affect the mixing of the
background fluid, nutrients, salinity etc.
24. Alignment in shear flow
Edwards and Yeomans numerically found different states but only
considered single mode solutions.
25. Backflow/Kickback
The third case we consider is a classic
example of director-flow coupling in liquid
crystals.
There may be interesting parallels in
active fluid systems.
Here we start with the same system as in
the first case but with a different initial
state.
The active nematic may have been aligned
by a variety of external influences:
magnetic field, light source, food source…
26. Backflow/Kickback
We first linearise about the state
The linearised governing equations are similar to the first case
and we seek solutions of the form
27. Backflow/Kickback
The modenumber and associated time constant are determined by,
Because is negative and is positive, the time constant
is negative (i.e. all modes decay) when the activity parameter is not
negative.
28. Backflow/Kickback
For we get a number of modes determined by
The high order modes decay, causing kickback and leaving a single mode.
35. Future questions
What happens if density and order are included in models of active
nematics?
Most marine based microorganisms are polar; how does this break in
symmetry affect the results?
How realistic is it to use continuum models for large organisms?
How do active species affect mixing?
What happens in 2d or 3d?
Acknowledgements – Allan Sharkie, SAMS, MRC (for future funding)