6,464 research outputs found
Method and apparatus for fabricating improved solar cell modules
A method and apparatus for fabricating an improved solar cell module is described. The apparatus includes a supply drum for feeding a flexible strip having etched electrical circuitry deposited on it a supply drum for feeding into overlying engagement with the flexible strip a flexible tape having a pair of exposed tacky surfaces, and a plurality of rams for receiving and depositing a plurality of solar cells in side-by-side relation on an exposed tacky surface of the tape in electrical contacting engagement with the etched circuitry
Torque and temperature dependence of the hysteretic voltage-induced torsional strain in tantalum trisulfide
We have measured the dependence of the hysteretic voltage-induced torsional
strain (VITS) in crystals of orthorhombic tantalum trisulfide on temperature
and applied torque. In particular, applying square-wave voltages above the
charge-density-wave (CDW) threshold voltage, so as to abruptly switch the
strain across its hysteresis loop, we have found that the time constant for the
VITS to switch (at different temperatures and voltages) varied as the CDW
current. Application of torque to the crystal could also change the VITS time
constant, magnitude, and sign, suggesting that the VITS is a consequence of
residual torsional strain in the sample which twist the CDW. Application of
voltage changes the pitch of these CDW twists, which then act back on the
lattice. However, it remains difficult to understand the sluggishness of the
response.Comment: 20 pages, including 7 figures, to be published in PR
Ground Water Monitoring Project for Arkansas, Phase III
This report is composed of two parts. The first part is an interpretation of the pesticide and nitrate data collected in Woodruff County based on samples collected during 1994. Because there is an indication that there were hydrological differences between 1994 and 1995, and because most of the pesticide data is from 1994, this interpretive portion is restricted to 1994 data. Six wells initially sampled in 1994 that contained pesticides had continuing contamination in re-sampling in 1994 and 1995. Part II lists a seventh well in Woodruff County that contained pesticides in February and May of 199
Laser transit anemometer measurements on a slender cone in the Langley unitary plan wind tunnel
A laser transit anemometer (LTA) system was used to probe the boundary layer on a slender (5 degree half angle) cone model in the Langley unitary plan wind tunnel. The anemometer system utilized a pair of laser beams with a diameter of 40 micrometers spaced 1230 micrometers apart to measure the transit times of ensembles of seeding particles using a cross-correlation technique. From these measurements, boundary layer profiles around the model were constructed and compared with CFD calculations. The measured boundary layer profiles representing the boundary layer velocity normalized to the edge velocity as a function of height above the model surface were collected with the model at zero angle of attack for four different flow conditions, and were collected in a vertical plane that bisected the model's longitudinal center line at a location 635 mm from the tip of the forebody cone. The results indicate an excellent ability of the LTA system to make velocity measurements deep into the boundary layer. However, because of disturbances in the flow field caused by onboard seeding, premature transition occurred implying that upstream seeding is mandatory if model flow field integrity is to be maintained. A description and results of the flow field surveys are presented
Completion Report: Pesticide and Nitrate Monitoring Results for Craighead, Mississippi, and Poinsett Counties, Arkansas: Phase II
Because of the concern for potential contamination of ground water by agricultural chemicals, 38 wells drilled in the Mississippi River Valley alluvial aquifer in Mississippi County and the eastern parts of Craighead and Poinsett Counties, Arkansas were analyzed for pesticides and nitrate. The pesticide, fluometuron, was detected in one sample at a concentration of 0.5 mg/L. Bentazon was detected in three samples at concentrations of 2.5, 0.3, and 0.3 mg/L. The occurrences of the pesticides appear to represent isolated incidents rather than a widespread aquifer contamination. All detections were below health and safety standards. Nitrate is present in several wells at concentrations above 0.15 mg/L, one of which exceeded the EPA established maximum contaminant level for drinking water of 10 milligrams per liter as nitrogen. Except for two wells nitrate and iron are not present together at concentrations above 0.15 mg!L. This is probably due to microbially mediated reactions. Nitrate concentrations above 0.15 mg/L is only present in wells that are less than 60 feet deep and near permeable soils. Iron is present in wells that are not near permeable soils or wells that are greater than 40 feet deep, and may exceed 1 mg/L in some cases
Equivalences between spin models induced by defects
The spectrum of integrable spin chains are shown to be independent of the
ordering of their spins. As an application we introduce defects (local spin
inhomogeneities in homogenous chains) in two-boundary spin systems and, by
changing their locations, we show the spectral equivalence of different
boundary conditions. In particular we relate certain nondiagonal boundary
conditions to diagonal ones.Comment: 14 pages, 16 figures, LaTeX, Extended versio
Instability driven fragmentation of nanoscale fractal islands
Formation and evolution of fragmentation instabilities in fractal islands,
obtained by deposition of silver clusters on graphite, are studied. The
fragmentation dynamics and subsequent relaxation to the equilibrium shapes are
controlled by the deposition conditions and cluster composition. Sharing common
features with other materials' breakup phenomena, the fragmentation instability
is governed by the length-to-width ratio of the fractal arms.Comment: 5 pages, 3 figures, Physical Review Letters in pres
Structure of the two-boundary XXZ model with non-diagonal boundary terms
We study the integrable XXZ model with general non-diagonal boundary terms at
both ends. The Hamiltonian is considered in terms of a two boundary extension
of the Temperley-Lieb algebra.
We use a basis that diagonalizes a conserved charge in the one-boundary case.
The action of the second boundary generator on this space is computed. For the
L-site chain and generic values of the parameters we have an irreducible space
of dimension 2^L. However at certain critical points there exists a smaller
irreducible subspace that is invariant under the action of all the bulk and
boundary generators. These are precisely the points at which Bethe Ansatz
equations have been formulated. We compute the dimension of the invariant
subspace at each critical point and show that it agrees with the splitting of
eigenvalues, found numerically, between the two Bethe Ansatz equations.Comment: 9 pages Latex. Minor correction
Metagenetic analysis of patterns of distribution and diversity of marine meiobenthic eukaryotes
AimMeiofaunal communities that inhabit the marine benthos offer unique opportunities to simultaneously study the macroecology of numerous phyla that exhibit different life-history strategies. Here, we ask: (1) if the macroecology of meiobenthic communities is explained mainly by dispersal constraints or by environmental conditions; and (2) if levels of meiofaunal diversity surpass existing estimates based on morphological taxonomy. LocationUK and mainland European coast. MethodsNext-generation sequencing techniques (NGS; Roche 454 FLX platform) using 18S nuclear small subunit ribosomal DNA (rDNA) gene. Pyrosequences were analysed using AmpliconNoise followed by chimera removal using Perseus. ResultsRarefaction curves revealed that sampling saturation was only reached at 15% of sites, highlighting that the bulk of meiofaunal diversity is yet to be discovered. Overall, 1353 OTUs were recovered and assigned to 23 different phyla. The majority of sampled sites had c. 60-70 unique operational taxonomic units (OTUs) per site, indicating high levels of beta diversity. The environmental parameters that best explained community structure were seawater temperature, geographical distance and sediment size, but most of the variability (R-2=70%-80%) remains unexplained. Main conclusionsHigh percentages of endemic OTUs suggest that meiobenthic community composition is partly niche-driven, as observed in larger organisms, but also shares macroecological features of microorganisms by showing high levels of cosmopolitanism (albeit on a much smaller scale). Meiobenthic communities exhibited patterns of isolation by distance as well as associations between niche, latitude and temperature, indicating that meiobenthic communities result from a combination of niche assembly and dispersal processes. Conversely, isolation-by-distance patterns were not identified in the featured protists, suggesting that animals and protists adhere to radically different macroecological processes, linked to life-history strategies.Natural Environment Research Council (NERC) [NE/E001505/1, NE/F001266/1, MGF-167]; Portuguese Foundation for Science and Technology (FCT) [SFRH/BD/27413/2006, SFRH/BPD/80447/2014]; EPSRC [EP/H003851/1]; BBSRC CASE studentship; Unilever; Biotechnology and Biological Sciences Research Council [987347]; Engineering and Physical Sciences Research Council [EP/H003851/1]; Natural Environment Research Council [NE/F001290/1, NE/F001266/1, NE/E001505/1, NBAF010002]info:eu-repo/semantics/publishedVersio
- …