2011-2012 Bulletin – PDF - SEAS Bulletin - Columbia University

Biomechanics and Mechanics of
Materials. Some of the current
research in biomechanics is concerned
with the application of continuum
theories of mixtures to problems of
electromechanical behavior of soft
biological tissues, contact mechanics,
lubrication of diarthrodial joints, and
cartilage tissue engineering. (Ateshian)
In the area of the mechanics of
materials, research is performed to better
understand material constitutive behavior
at the micro- and mesolength scales.
This work is experimental, theoretical, and
computational in nature. The ultimate goal
is to formulate constitutive relationships
that are based on physical concepts
rather than phenomenology, as in the
case of plasticity power-law hardening.
In addition, the role that the constitutive
relations play in the fracture and failure of
materials is emphasized. (Kysar)
In the area of molecular mechanics in
biology, mechanical effects on stem cell
differentiation is studied to understand
the underlying molecular mechanisms.
The molecular motion in living cells is
monitored to examine how the dynamics
of molecules determine the specificity of
stem cell differentiation. Mechanics of
molecular motors is studied to correlate
their functions with cell differentiation. (Liao)
Other areas of biomechanics
include characterizing the structurefunction
behavior of the cervix during
the remodeling events of pregnancy
and characterizing the mechanical
properties of the eye-wall in relation to
glaucoma. Research in our lab includes
the mechanical testing of biological soft
tissues, the biochemical analysis of tissue
microstructure, and material modeling
based on structure-mechanical property
relationships. In collaboration with
clinicians, our goal is to understand the
etiologies of tissue pathology and disease.
(Myers)
Control, Design, and Manufacturing.
Control research emphasizes iterative
learning control (ILC) and repetitive
control (RC). ILC creates controllers
that learn from previous experience
performing a specific command,
such as robots on an assembly line,
aiming for high-precision mechanical
motions. RC learns to cancel repetitive
disturbances, such as precision motion
through gearing, machining, satellite
precision pointing, particle accelerators,
etc. Time optimal control of robots is
being studied for increased productivity
on assembly lines through dynamic
motion planning. Research is also
being conducted on improved system
identification, making mathematical
models from input-output data. The
results can be the starting point for
designing controllers, but they are
also studied as a means of assessing
damage in civil engineering structures
from earthquake data. (Longman)
In the area of advanced
manufacturing processes and systems,
current research concentrates on laser
materials processing. Investigations
are being carried out in laser
micromachining; laser forming of sheet
metal; microscale laser shock-peening,
material processing using improved
laser-beam quality. Both numerical and
experimental work is conducted using
state-of-the-art equipment, instruments,
and computing facilities. Close ties
with industry have been established for
collaborative efforts. (Yao)
Energy, Fluid Mechanics, and Heat/
Mass Transfer. In the area of energy,
one effort addresses the design of
flow/mass transport systems for the
extraction of carbon dioxide from
air. Another effort addresses the
development of distributed sensors for
use in micrositing and performance
evaluation of energy and environmental
systems. The design and testing
of components and systems for
micropower generation is part of the
thermofluids effort as well as part of the
MEMS effort. (Modi)
In the area of fluid mechanics, study
of low-Reynolds-number chaotic flows
is being conducted both experimentally
and numerically, and the interactions
with molecular diffusion and inertia are
presently being investigated. Other
areas of investigation include the fluid
mechanics of inkjet printing, drop on
demand, the suppression of satellite
droplets, shock wave propagation, and
remediation in high-frequency printing
systems. (Modi)
In the area of nanoscale thermal
transport, our research efforts center on
the enhancement of thermal radiation
transport across interfaces separated by
a nanoscale gap. The scaling behavior
of nanoscale radiation transport is
measured using a novel heat transfer
measurement technique based on
the deflection of a bimaterial atomic
force microscope cantilever. Numerical
simulations are also performed to
confirm these measurements. The
measurements are also used to infer
extremely small variations of van der
Waals forces with temperature. This
enhancement of radiative transfer will
ultimately be used to improve the power
density of thermophotovoltaic energy
conversion devices. (Narayanaswamy)
Research in the area of tribology—the
study of friction, lubrication, and wear—
focuses on studying the wear damage
and energy loss that is experienced in
power generation components such
as piston rings, fuel injection systems,
geartrains, and bearings. Next-generation
lubricants, additives, surface coatings,
and surface finishes are being studied in
order to determine their effects on friction
and wear. Additionally, environmentally
friendly lubricants are also being identified
and characterized. (Terrell)
MEMS and Nanotechnology. In these
areas, research activities focus on power
generation systems, nanostructures for
photonics, fuel cells and photovoltaics,
and microfabricated adaptive cooling
skin and sensors for flow, shear, and
wind speed. Basic research in fluid
dynamics and heat/mass transfer
phenomena at small scales also support
these activities. (Hone, Lin, Modi,
Narayanaswamy, Wong)
We study the dynamics of
microcantilevers and atomic force
microscope cantilevers to use them
as microscale thermal sensors based
on the resonance frequency shifts
of vibration modes of the cantilever.
Bimaterial microcantilever-based
sensors are used to determine the
thermophysical properties of thin films.
(Narayanaswamy)
Research in the area of
nanotechnology focuses on
nanomaterials such as nanotubes
and nanowires and their applications,
especially in nanoelectromechanical
systems (NEMS). A laboratory is available
for the synthesis of carbon nanotubes
and semiconductor nanowires using
chemical vapor deposition (CVD)
techniques and to build devices using
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engineering 2011–2012