7,516 research outputs found
Anisotropic Relaxation Functions and Strength of Oriented Solids Technical Report No. 106
Anisotropic relaxation functions and strength of oriented solid
Energy absorption by polymer crazing
During the past thirty years, a tremendous amount of research was done on the development of crazing in polymers. The phenomenon of crazing was recognized as an unusual deformation behavior associated with a process of molecular orientation in a solid to resist failure. The craze absorbs a fairly large amount of energy during the crazing process. When a craze does occur the surrounding bulk material is usually stretched to several hundred percent of its original dimension and creates a new phase. The total energy absorbed by a craze during the crazing process in creep was calculated analytically with the help of some experimental measurements. A comparison of the energy absorption by the new phase and that by the original bulk uncrazed medium is made
Kinetic considerations of the strength of oriented solids
Kinetics of mechanical strength of oriented and stressed solids based on statistical absolute reaction rate theor
Theoretical Consideration of the Influence of Reforming Processes on the Fracture Strength of Solids Technical Report No. 105
Reformation processes effect on stress time-to- fracture behavior of solid
Quantitation of buried contamination by use of solvents
Experiments directed at determining the potential of reclaimed silicone polymers for reuse are described
Quantitation of buried contamination by use of solvents
Spore recovery form cured silicone potting compounds using amine solvents to degrade the cured polymers was investigated. A complete list of solvents and a description of the effect of each on two different silicone polymers is provided
Recommended from our members
Characterisation of the mechanobiology of stents in vitro
This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Long-term efficacy of percutaneous coronary intervention (PCI) to treat coronary heart disease is hampered by incidence of in-stent restenosis (ISR). The regrowth of a healthy endothelial layer post-treatment, a key factor in successful vascular repair, has been shown to be affected by the high sensitivity of endothelial cells (EC) to shear stress. Characterisation of stented artery haemodynamics is required to understand the response of EC to complex flow and shear stress patterns induced by stent structure. A device for the in vitro study of coronary stents has been developed and fabricated in polydimethylsiloxane (PDMS). Balloon-mounted cobalt-chromium stents have been successfully deployed, and particle tracking has been employed to obtain streamlines under low flow rate. High-resolution flow-patterns can be imaged, and complemented with in silico analysis from μCT data. The device allows for the seeding of EC, and sustained exposure to shear stress. EC response can be investigated by comparing real-time footage of cellular migration and proliferation to the haemodynamics of the specific region
Accretion and photodesorption of CO ice as a function of the incident angle of deposition
Non-thermal desorption of inter- and circum-stellar ice mantles on dust
grains, in particular ultraviolet photon-induced desorption, has gained
importance in recent years. These processes may account for the observed gas
phase abundances of molecules like CO toward cold interstellar clouds. Ice
mantle growth results from gas molecules impinging on the dust from all
directions and incidence angles. Nevertheless, the effect of the incident angle
for deposition on ice photo-desorption rate has not been studied. This work
explores the impact on the accretion and photodesorption rates of the incidence
angle of CO gas molecules with the cold surface during deposition of a CO ice
layer. Infrared spectroscopy monitored CO ice upon deposition at different
angles, ultraviolet-irradiation, and subsequent warm-up. Vacuum-ultraviolet
spectroscopy and a Ni-mesh measured the emission of the ultraviolet lamp.
Molecules ejected from the ice to the gas during irradiation or warm-up were
characterized by a quadrupole mass spectrometer. The photodesorption rate of CO
ice deposited at 11 K and different incident angles was rather stable between 0
and 45. A maximum in the CO photodesorption rate appeared around
70-incidence deposition angle. The same deposition angle leads to the
maximum surface area of water ice. Although this study of the surface area
could not be performed for CO ice, the similar angle dependence in the
photodesorption and the ice surface area suggests that they are closely
related. Further evidence for a dependence of CO ice morphology on deposition
angle is provided by thermal desorption of CO ice experiments
Violating conformal invariance: Two-dimensional clusters grafted to wedges, cones, and branch points of Riemann surfaces
We present simulations of 2-d site animals on square and triangular lattices
in non-trivial geomeLattice animals are one of the few critical models in
statistical mechanics violating conformal invariance. We present here
simulations of 2-d site animals on square and triangular lattices in
non-trivial geometries. The simulations are done with the newly developed PERM
algorithm which gives very precise estimates of the partition sum, yielding
precise values for the entropic exponent (). In particular, we studied animals grafted to the tips of wedges
with a wide range of angles , to the tips of cones (wedges with the
sides glued together), and to branching points of Riemann surfaces. The latter
can either have sheets and no boundary, generalizing in this way cones to
angles degrees, or can have boundaries, generalizing wedges. We
find conformal invariance behavior, , only for small
angles (), while for
. These scalings hold both for wedges and cones. A heuristic
(non-conformal) argument for the behavior at large is given, and
comparison is made with critical percolation.Comment: 4 pages, includes 3 figure
- …