1,729 research outputs found
Dominant atmospheric pollutants in malaysia
This Article presents a Brief of the various types of Pollutants that are contributing to the problem of air pollution in Malaysia, As well as the mention of some episodes in air pollution that have given rise to concern her
Error estimation of bilinear Galerkin finite element method for 2D thermal problems
This study demonstrates a two-dimensional steady state heat conduction Laplace partial differential equation solution using the bilinear Galerkin finite element method. Heat transfer analysis is of vital importance in many engineering applications and devising computationally inexpensive numerical methods while maintaining accuracy is one of the primary concerns. The method uses structured mesh grid over a two-dimensional rectangular domain and solved using a stiffness matrix for the bilinear elements, calculated using the proposed modified numerical scheme. Several numerical experiments are conducted by controlling the number of nodes and changing element sizes of the presented scheme, and comparison made between analytical solution and software generated solution
Economical (k,m)-threshold controlled quantum teleportation
We study a (k,m)-threshold controlling scheme for controlled quantum
teleportation. A standard polynomial coding over GF(p) with prime p > m-1 needs
to distribute a d-dimensional qudit with d >= p to each controller for this
purpose. We propose a scheme using m qubits (two-dimensional qudits) for the
controllers' portion, following a discussion on the benefit of a quantum
control in comparison to a classical control of a quantum teleportation.Comment: 11 pages, 2 figures, v2: minor revision, discussions improved, an
equation corrected in procedure (A) of section 4.3, v3: major revision,
protocols extended, citations added, v4: minor grammatical revision, v5:
minor revision, discussions extende
The relative importance of head, flux, and prior information in hydraulic tomography analysis
Using cross-correlation analysis, we demonstrate that flux measurements at observation locations during hydraulic tomography (HT) surveys carry nonredundant information about heterogeneity that are complementary to head measurements at the same locations. We then hypothesize that a joint interpretation of head and flux data, even when the same observation network as head has been used, can enhance the resolution of HT estimates. Subsequently, we use numerical experiments to test this hypothesis and investigate the impact of flux conditioning and prior information (such as correlation lengths and initial mean models (i.e., uniform mean or distributed means)) on the HT estimates of a nonstationary, layered medium. We find that the addition of flux conditioning to HT analysis improves the estimates in all of the prior models tested. While prior information on geologic structures could be useful, its influence on the estimates reduces as more nonredundant data (i.e., flux) are used in the HT analysis. Lastly, recommendations for conducting HT surveys and analysis are presented
Multiscale mechanisms of nutritionally induced property variation in spider silks.
Variability in spider major ampullate (MA) silk properties at different scales has proven difficult to determine and remains an obstacle to the development of synthetic fibers mimicking MA silk performance. A multitude of techniques may be used to measure multiscale aspects of silk properties. Here we fed five species of Araneoid spider solutions that either contained protein or were protein deprived and performed silk tensile tests, small and wide-angle X-ray scattering (SAXS/WAXS), amino acid composition analyses, and silk gene expression analyses, to resolve persistent questions about how nutrient deprivation induces variations in MA silk mechanical properties across scales. Our analyses found that the properties of each spider's silk varied differently in response to variations in their protein intake. We found changes in the crystalline and non-crystalline nanostructures to play specific roles in inducing the property variations we found. Across treatment MaSp expression patterns differed in each of the five species. We found that in most species MaSp expression and amino acid composition variations did not conform with our predictions based on a traditional MaSp expression model. In general, changes to the silk's alanine and proline compositions influenced the alignment of the proteins within the silk's amorphous region, which influenced silk extensibility and toughness. Variations in structural alignment in the crystalline and non-crystalline regions influenced ultimate strength independent of genetic expression. Our study provides the deepest insights thus far into the mechanisms of how MA silk properties vary from gene expression to nanostructure formations to fiber mechanics. Such knowledge is imperative for promoting the production of synthetic silk fibers
Frictional Coulomb drag in strong magnetic fields
A treatment of frictional Coulomb drag between two 2-dimensional electron
layers in a strong perpendicular magnetic field, within the independent
electron picture, is presented. Assuming fully resolved Landau levels, the
linear response theory expression for the transresistivity is
evaluated using diagrammatic techniques. The transresistivity is given by an
integral over energy and momentum transfer weighted by the product of the
screened interlayer interaction and the phase-space for scattering events. We
demonstrate, by a numerical analysis of the transresistivity, that for
well-resolved Landau levels the interplay between these two factors leads to
characteristic features in both the magnetic field- and the temperature
dependence of . Numerical results are compared with recent
experiments.Comment: RevTeX, 34 pages, 8 figures included in tex
Phonon mediated drag in double layer two dimensional electron systems
Experiments studying phonon mediated drag in the double layer two dimensional
electron gas system are reported. Detailed measurements of the dependence of
drag on temperature, layer spacing, density ratio, and matched density are
discussed. Comparisons are made to theoretical results [M. C. Bonsager et al.,
Phys. Rev. B 57, 7085 (1998)] which propose the existence of a new coupled
electron-phonon collective mode. The layer spacing and density dependence at
matched densities for samples with layer spacings below 2600 A do not support
the existence of this mode, showing behavior expected for independent electron
and phonon systems. The magnitude of the drag, however, suggests the alternate
limit; one in which electrons and phonons are strongly coupled. The results for
still larger layer spacing show significant discrepancies with the behavior
expected for either limit.Comment: 9 pages, 9 figures, Late
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