BEGIN:VCALENDAR
PRODID:-//PSU Mathematics Department//Seminar iCalendar Generator//EN
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CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:Computational and Applied Mathematics Colloquium
X-WR-TIMEZONE:America/New_York
BEGIN:VTIMEZONE
TZID:America/New_York
X-LIC-LOCATION:America/New_York
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:19700308T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:19701101T020000
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
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END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20140825T143000
DTEND;TZID=America/New_York:20140825T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22709
SUMMARY:Computational and Applied Mathematics Colloquium - Transport of Cha
rged Particles in Physical and Biological Environments: An Energetic Varia
tional Approach
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Transport of Charged Particles in Physical and Biological Environments:
An Energetic Variational Approach\nSpeaker: Chun Liu\, Penn State Univers
ity\nAbstract: I will present a thermodynamics-consistent framework for st
udying the transport of charged particles in various environments. We will
explore various physical and mathematical descriptions for 1) the free en
ergy corresponding to the local and nonlocal interactions between particle
s as well as 2) dissipation mechanisms. For this talk\, I will just focus
on various classical and popular general diffusion problems\, such as frac
tional Laplacian\, porous media\, nonlocal diffusion as well as various st
ochastic interpretations.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20140901T143000
DTEND;TZID=America/New_York:20140901T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22710
SUMMARY:Computational and Applied Mathematics Colloquium - Labor Day\, no c
lasses
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Labor Day\, no classes\nSpeaker: Labor Day\, no classes
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20140908T143000
DTEND;TZID=America/New_York:20140908T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22711
SUMMARY:Computational and Applied Mathematics Colloquium - Evolution of soc
ial instincts in within- and between-group conflicts
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Evolution of social instincts in within- and between-group conflicts\n
Speaker: Sergey Gavrilets\, University of Tennessee (Host: A Belmonte)\nAb
stract: I model the effects of within-group inequality on the evolution of
social\ninstincts\, i.e. genetically-based propensities and biases that a
ffect the\nbehavior of individuals in social interactions. First\, I consi
der competitive\nwithin-group interactions. I identify a novel mechanism f
or the\nevolutionary emergence of the "egalitarian syndrome" and leveling
\ncoalitions in which one helps the weak against the strong bully. Second
\,\nI study a collective action problem in between-group conflicts and sho
w\nhow bullies can dialectically become "altruists". The mechanisms I desc
ribe\ndo not require genetic relatedness\, reciprocity\, reputation\, or p
unishment.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20140915T143000
DTEND;TZID=America/New_York:20140915T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22712
SUMMARY:Computational and Applied Mathematics Colloquium - Traveling waves
in lattices of oscillators
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Traveling waves in lattices of oscillators\nSpeaker: Mark Levi\, Penn S
tate University
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20140922T143000
DTEND;TZID=America/New_York:20140922T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22713
SUMMARY:Computational and Applied Mathematics Colloquium - Applications and
Discretizations for the Poisson-Nernst-Planck System
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Applications and Discretizations for the Poisson-Nernst-Planck System\n
Speaker: Maximilian Metti\, Penn State University\nAbstract: Many devices
involving charged particles or electric current can be modeled using the P
oisson-Nernst-Planck (PNP) equations. We investigate this system of equati
ons along with some standard modifications found in applications to engine
ering and biological contexts. Further consideration is given to discrete
formulations of the PNP system and a numerical approach for computing a so
lution.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20140929T143000
DTEND;TZID=America/New_York:20140929T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22714
SUMMARY:Computational and Applied Mathematics Colloquium - Blended Atomisti
c/Continuum Hybrid Methods for crystalline materials
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Blended Atomistic/Continuum Hybrid Methods for crystalline materials\nS
peaker: Xingjie Li\, Brown University (C Liu/X Li)\nAbstract: We consider
two prototypical atomistic-to-continuum coupling methods of blending type:
the energy-based and the force-based quasicontinuum methods\, with a comp
rehensive error analysis that is valid in two and three dimensions\, for f
inite many-body interactions (e.g.\, EAM type)\, and in the presence of la
ttice defects (point defects and dislocations). Based on a precise choice
of blending mechanism\, the error estimates are considered in terms of deg
rees of freedom. The numerical experiments confirm the theoretical predict
ions\, and demonstrate a superior accuracy of the force-based blending ove
r energy-based blending schemes.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141006T143000
DTEND;TZID=America/New_York:20141006T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22715
SUMMARY:Computational and Applied Mathematics Colloquium - Extracting and p
redicting spatiotemporal patterns from data with dynamics-adapted kernels
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Extracting and predicting spatiotemporal patterns from data with dynami
cs-adapted kernels\nSpeaker: Dimitrios Giannakis\, New York University (Ho
st: J Harlim)\nAbstract: Kernel methods provide an attractive way of extra
cting features from data by biasing their geometry in a controlled manner.
In this talk\, we discuss a family of kernels for dynamical systems featu
ring an explicit dependence on the dynamical vector field operating in the
phase-space manifold\, estimated empirically through finite differences o
f time-ordered data samples. The associated diffusion operator for data an
alysis is adapted to the dynamics in that it generates diffusions along th
e integral curves of the dynamical vector field. We present applications t
o toy dynamical systems and comprehensive climate models. We also discuss
a technique for analog forecasting based on these kernels. In this empiric
al forecasting technique\, kernels are used to create weighted ensembles o
f states (analogs) with high similarity to the initial data from a record
of historical observations\, and the future values of observables are pred
icted from the historical evolution of the ensemble.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141010T140000
DTEND;TZID=America/New_York:20141010T142500
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=25627
SUMMARY:Computational and Applied Mathematics Colloquium - Coffee Break
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Coffee Break\nAbstract Link: http://
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141010T143000
DTEND;TZID=America/New_York:20141010T153000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=24477
SUMMARY:Computational and Applied Mathematics Colloquium - How do dispersed
inertial particles modify turbulent flows ?
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: How do dispersed inertial particles modify turbulent flows ?\nSpeaker:
Said Elghobashi\, University of California\, Irvine (Host: J Xu)\nAbstract
: Turbulent flows laden with inertial particles are ubiquitous in nature (
e.g. aerosols in clouds\, and dust storms on Earth and Mars) and in indust
rial applications (e.g. liquid fuel and pulverized coal sprays in combusti
on chambers). Experimental and numerical studies of these flows are quite
challenging due to the wide spectra of length- and time- scales of the\ndi
spersed particles in addition to the spectra of scales intrinsic to the ca
rrier fluid turbulence.\n\nThe two-way and and four-way nonlinear interact
ions between the dispersed particles and the turbulence result in complex
multi-scale physical phenomena. The lecture focuses on the physical mechan
isms of interactions between dispersed spherical particles and isotropic t
urbulence using Direct Numerical Simulation (DNS). Particles whose diamete
r is smaller than the Kolmogorov length scale are simulated as point parti
cles. Larger particles with\ndiameter of the order of Taylor microscale ar
e fully resolved using the Immersed Boundary method.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141013T143000
DTEND;TZID=America/New_York:20141013T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22716
SUMMARY:Computational and Applied Mathematics Colloquium - Boltzmann and Fo
kker-Planck Equations for Economic Modeling
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Boltzmann and Fokker-Planck Equations for Economic Modeling\nSpeaker: B
ruce Boghosian\, Tufts University (C Liu)\nAbstract: The Boltzmann equatio
n provides a continuum description of a population of particles undergoing
pairwise interactions in which they can exchange momentum and energy. An
economy consists of economic agents who engage in pairwise transactions i
n which they can exchange wealth. It has long been suggested that it ough
t to be possible to write a Boltzmann equation that describes an economy.
This work describes how to do exactly that for a simplified microeconomic
model\, called the "Yard-Sale Model." We also show how\, in the limit of
small transactions\, this Boltzmann equation reduces to a nonlinear Fokke
r-Planck equation for the probability distribution function of wealth.\n\n
Stability of a market economy is one of the fundamental tenets of classica
l and neoclassical economics\, dating back at least to Adam Smith's "invis
ible hand" concept. In spite of that\, we find that our model market econ
omy is highly unstable\, with a strong tendency toward oligarchy. Mathema
tically\, its time-asymptotic state is a singular distribution. It can be
stabilized by adding some mechanism for wealth redistribution\, such as a
wealth tax\, in which case its steady state is shown to be similar to the
the famous Pareto distribution\, with a cutoff at very low values of weal
th and power-law decay at very high values. Indeed\, this appears to be t
he first detailed microeconomic explanation of Pareto's century-old law of
wealth distribution\, a key observation of macroeconomics.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141020T143000
DTEND;TZID=America/New_York:20141020T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=25479
SUMMARY:Computational and Applied Mathematics Colloquium - The Phase Field
Crystal Model: A Continuum Framework for Studying Phase Transformations on
Atomic Length and Diffusive Time Scales
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: The Phase Field Crystal Model: A Continuum Framework for Studying Phase
Transformations on Atomic Length and Diffusive Time Scales\nSpeaker: Stev
en Wise\, University of Tennessee (Host: M Metti)\nAbstract: Crystalline m
aterials contain atomic-scale imperfections in the form of defects – suc
h as vacancies\, grain boundaries\, and dislocations – and controlling\,
or at least predicting\, the formation and evolution of such imperfection
s during phase transformation is a major challenge. The phase field cryst
al (PFC) methodology has emerged as a important\, increasingly-preferred m
odeling framework for studying materials with atomic-scale structures on d
iffusive time scales. In contrast to molecular dynamics models\, the fast
atomic vibrational time-scale phenomena are averaged out\, in essence\, bu
t the atomic spatial resolution is preserved. In this talk\, I will descr
ibe some analysis (existence and uniqueness)\, approximation\, and fast co
mputation of solutions to PFC and PFC-type equations\, a family of highly
nonlinear hyperbolic-parabolic PDE and integro-PDE. I will also discuss a
new PFC framework for multi-spatial-scale modeling based on the recent met
hod of amplitude expansions. This presentation will be accessible to grad
uate students.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141027T143000
DTEND;TZID=America/New_York:20141027T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22718
SUMMARY:Computational and Applied Mathematics Colloquium - Discretization o
f time-dependent quantum systems: propagation of the evolution operator
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Discretization of time-dependent quantum systems: propagation of the ev
olution operator\nSpeaker: Joseph Jerome\, Northwestern University\nAbstra
ct: The talk represents joint work with Eric Polizzi and is based on a pap
er of similar title recently published online in Applicable Analysis. We d
iscuss time-dependent quantum systems on bounded domains\; these represent
closed systems and are relevant for application to Carbon Nanotubes and m
olecules. Included in our framework are linear iterations involved in time
-dependent density functional theory as well as the global nonlinear model
which includes the Hartree potential. A key aspect of the analysis of the
algorithms is the use of time-ordered evolution operators\, which allow f
or both a well-posed problem and its approximation. The approximation theo
rems we obtain are operator extensions of classical quadrature theorems. T
he global existence theorem uses the Leray-Schauder fixed point theorem\,
coupled to a modified conservation of energy principle. The simulations we
re performed by Eric Polizzi using his algorithm FEAST. The evolution oper
ators used in the talk are due to T. Kato and their properties will be sum
marized. Application areas make significant use of these operators\, parti
cularly chemical physics. In the mathematical literature\, the Euclidean s
pace problem has been studied by T. Cazenave and others\, employing the St
richartz inequalities. These are ultimately based on semi-groups. Our resu
lts appear to be complementary to results of this type. The solutions we d
iscuss are strong solutions. We are currently studying more general potent
ials via weak solutions. This work is in-progress.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141103T143000
DTEND;TZID=America/New_York:20141103T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22719
SUMMARY:Computational and Applied Mathematics Colloquium - Multiple Numeric
al Solutions and Stability of Transonic Flows over Airfoils
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Multiple Numerical Solutions and Stability of Transonic Flows over Airf
oils\nSpeaker: Feng Liu\, University of California\, Irvine (Host: J Xu)\n
Abstract Link: http://fliu.eng.uci.edu\nAbstract: Following a general pres
entation on the numerical simulation of steady and unsteady transonic flow
s over wings and turbomachinery blade rows by using computational fluid dy
namics\, I will focus on the findings of multiple numerical solutions for
the Transonic Small-Disturbance equation and the Euler equations. Both sym
metric and asymmetric solutions are possible for a symmetric airfoil at ze
ro angle of attack within a certain free-stream Mach number range. The sta
bility of the multiple solutions is analyzed using numerical methods. It i
s found\, the symmetric solutions tend to be unstable\, while the asymmetr
ic solutions are stable. I will discuss the relevance of such stability an
alysis to the intrinsic unsteady behavior of transonic buffet over airfoil
s and wings.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141110T143000
DTEND;TZID=America/New_York:20141110T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22720
SUMMARY:Computational and Applied Mathematics Colloquium - Scalable Implici
t Resistive MHD with Stabilized Finite Element Methods and Fully-Coupled N
ewton-Krylov-AMG Solution Methods
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Scalable Implicit Resistive MHD with Stabilized Finite Element Methods
and Fully-Coupled Newton-Krylov-AMG Solution Methods\nSpeaker: John Shadid
\, Sandia National Laboratory (Host: J Xu)\nAbstract: The resistive magnet
ohydrodynamics (MHD) model describes the dynamics of charged fluids in the
presence of electromagnetic fields. MHD models are used to describe impor
tant phenomena in the natural physical world and in technological applicat
ions. This model is non-self adjoint\, strongly coupled\, highly nonlinear
and characterized by multiple physical phenomena that span a very large r
ange of length- and time-scales. These interacting\, nonlinear multiple ti
me-scale physical mechanisms can balance to produce steady-state behavior
\, nearly balance to evolve a solution on a dynamical time-scale that is l
ong relative to the component time-scales\, or can be dominated by just a
few fast modes. These characteristics make the scalable\, robust\, accurat
e\, and efficient computational solution of these systems extremely challe
nging. For multiple-time-scale systems\, fully-implicit methods can be an
attractive choice that can often provide unconditionally-stable time integ
ration techniques. The stability of these methods\, however\, comes at a v
ery significant cost\, as these techniques generate large and highly nonli
near sparse algebraic systems of equations that must be solved at each tim
e step.\nThis talk describes the development of a scalable fully-implicit
stabilized unstructured finite element (FE) capability for 3D resistive MH
D. The brief discussion considers the development of the stabilized / vari
ational multiscale (VMS) FE formulation and the underlying fully-coupled p
reconditioned Newton-Krylov (NK) nonlinear iterative solver. The VMS formu
lation and the fully- coupled NK solution methods allow the simulation of
flow systems that range from incompressible to low Mach number compressibl
e flows\, as well as the development of a number of solution methods beyon
d forward simulation. The solution methods include parameter continuation
\, bifurcation\, optimization\, and adjoint-based methods for sensitivity
analysis\, error-estimation and UQ.\nTo enable robust\, scalable and effic
ient solution of the large-scale sparse linear systems generated by the Ne
wton linearization\, fully-coupled multilevel preconditioners are develope
d. The multilevel preconditioners are based on two differing approaches. T
he first technique employs a graph-based aggregation method applied to the
nonzero block structure of the Jacobian matrix. The second approach utili
zes approximate block decomposition methods and physics-based precondition
ing approaches that reduce the coupled systems into a set of simplified sy
stems to which multilevel methods are applied. To demonstrate the capabili
ty of these approaches representative results are presented for the soluti
on of challenging prototype MHD problems. These include duct flows\, an un
stable hydromagnetic Kelvin-Helmholtz shear layer\, and an island coalesce
nce problem used to model magnetic reconnection. In this context robustnes
s\, efficiency\, and the parallel and algorithmic scaling of solution meth
ods are discussed. Initial results that explore the scaling of the solutio
n methods are also presented on up to 128K processors for problems with up
to 1.8B unknowns on a CrayXK7.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141117T143000
DTEND;TZID=America/New_York:20141117T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22691
SUMMARY:Computational and Applied Mathematics Colloquium - An Unfitted hp-I
nterface Penalty Finite Element Method For Elliptic Interface Problems
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: An Unfitted hp-Interface Penalty Finite Element Method For Elliptic Int
erface Problems\nSpeaker: Yuanming Xiao\, Nanjing University\nAbstract: An
hp version of interface penalty finite element method (hp-IPFEM) is propo
sed for elliptic interface problems in two and three dimensions on unfitte
d meshes. Error estimates in broken H1 norm\, which are optimal with respe
ct to h and suboptimal with respect to p by half an order of p\, are deriv
ed. Both symmetric and non-symmetric IPFEM are considered. Error estimates
in L2 norm are proved by the duality argument.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141124T143000
DTEND;TZID=America/New_York:20141124T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22721
SUMMARY:Computational and Applied Mathematics Colloquium - Fall Break\, No
Seminar
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Fall Break\, No Seminar\nSpeaker: Fall Break\, No Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141201T143000
DTEND;TZID=America/New_York:20141201T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22722
SUMMARY:Computational and Applied Mathematics Colloquium - Uncertainty quan
tification and geophysical hazard mapping
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Uncertainty quantification and geophysical hazard mapping\nSpeaker: Ela
ine Spiller\, Marquette University (Host: J Conway)\nAbstract: PDE models
of granular flows are invaluable tools for developing probabilistic hazard
s maps for volcanic landslides\, but they are far from perfect. First\, an
y probabilistic hazard map is conditioned on assumptions about the aleator
ic uncertainty -- how mother nature rolls the dice -- and is hence tied to
the choice of probability distributions describing various scenarios (e.g
. initial and/or boundary conditions). Thus new data\, differing expert o
pinion\, or emergent scenarios may suggest that the original assumptions w
ere invalid and thus the hazard map made under those assumptions is not te
rribly useful. Epistemic uncertainty -- uncertainty due to a lack of mode
l refinement -- arises through assumptions made in physical models\, numer
ical approximation\, and imperfect statistical models. In the context of
geophysical hazard mapping\, we propose a surrogate-based methodology whic
h efficiently assesses the impact of various uncertainties enabling a quic
k yet methodical comparison of the effects of uncertainty and error on com
puter model output.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141208T143000
DTEND;TZID=America/New_York:20141208T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22723
SUMMARY:Computational and Applied Mathematics Colloquium - Solitary waves i
n non-integrable lattices
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: Solitary waves in non-integrable lattices\nSpeaker: Anna Vainchtein\, U
niversity of Pittsburgh (Host: X Li)\nAbstract: The interplay between disc
reteness and nonlinearity in many physical systems leads to the formation
of solitary waves. For example\, such waves were experimentally observed i
n granular materials\, electrical transmission lines and optical fibers. M
uch of the interest in these nonlinear waves was triggered by the pioneeri
ng study by Fermi\, Pasta and Ulam (1955). The subsequent work of Zabusky
and Kruskal (1965) has revolutionized the nonlinear science by connecting
the FPU problem to its continuum near-sonic limit described by the KdV equ
ation. In integrable systems solitary waves\, known as solitons\, are now
well understood\, with one-dimensional Toda lattice being the most promine
nt example that has an exact solution covering a broad range of behaviors
from delocalized low-energy waves in the KdV limit to highly localized hig
h-energy waves. Most discrete systems\, however\, are non-integrable. In t
his case understanding the transition from the KdV limit to the strongly d
iscrete waves has mostly relied on numerical and quasicontinuum approximat
ions. \n\nIn this talk I will review some of these results and describe re
cent work with Lev Truskinovsky on a non-integrable FPU problem with piece
wise quadratic potential. We construct an exact solitary wave solution tha
t captures the entire crossover velocity range between the low-energy limi
t and strongly localized waves that involve only one particle moving at a
time. The solution is expressed in the form of an infinite series. A trunc
ation of the series involving progressively smaller characteristic wavelen
gths produces a nested set of approximate solutions. Even the simplest sol
ution of this type that accounts only for the longest wave lengths provide
s a better overall approximation of solitary waves than some conventional
quasicontinuum models. \n\nI will also discuss recent work with Aaron Hof
fman\, Yuli Starostvetsky and Doug Wright on solitary waves in a diatomic
FPU lattices. At generic mass ratios\, pulses propagating through such lat
tices radiate lattice waves traveling behind them\, thus precluding format
ion of genuine solitary waves. However\, numerical simulations suggest tha
t under certain conditions there is a sequence of special 'anti-resonance'
values of mass ratio at which there is no radiation and solitary waves do
exist. Using multiscale asymptotic analysis\, we find a Fredholm-type con
dition\, made explicit for the diatomic Toda lattice\, for mass ratios app
roximating such values.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20141215T143000
DTEND;TZID=America/New_York:20141215T153000
LOCATION:MB106
URL:http://www.math.psu.edu/seminars/meeting.php?id=22724
SUMMARY:Computational and Applied Mathematics Colloquium - TBA
DESCRIPTION:Seminar: Computational and Applied Mathematics Colloquium\nTitl
e: TBA\nAbstract Link: http://
END:VEVENT
END:VCALENDAR