Condensers and or evaporators in convective and radiative environments

Condensers and/or evaporators in convective and radiative environment

Diffraction-limited CCD imaging with faint reference stars

By selecting short exposure images taken using a CCD with negligible readout noise we obtained essentially diffraction-limited 810 nm images of faint objects using nearby reference stars brighter than I=16 at a 2.56 m telescope. The FWHM of the isoplanatic patch for the technique is found to be 50 arcseconds, providing ~20% sky coverage around suitable reference stars.Comment: 4 page letter accepted for publication in Astronomy and Astrophysic

Stellar Differential Rotation and Coronal Timescales

We investigate the timescales of evolution of stellar coronae in response to surface differential rotation and diffusion. To quantify this we study both the formation time and lifetime of a magnetic flux rope in a decaying bipolar active region. We apply a magnetic flux transport model to prescribe the evolution of the stellar photospheric field, and use this to drive the evolution of the coronal magnetic field via a magnetofrictional technique. Increasing the differential rotation (i.e. decreasing the equator-pole lap time) decreases the flux rope formation time. We find that the formation time is dependent upon the geometric mean of the lap time and the surface diffusion timescale. In contrast, the lifetime of flux ropes are proportional to the lap time. With this, flux ropes on stars with a differential rotation of more than eight times the solar value have a lifetime of less than two days. As a consequence, we propose that features such as solar-like quiescent prominences may not be easily observable on such stars, as the lifetimes of the flux ropes which host the cool plasma are very short. We conclude that such high differential rotation stars may have very dynamical coronae

The full set of cnc_n-invariant factorized SS-matrices

We use the method of the tensor product graph to construct rational (Yangian invariant) solutions of the Yang-Baxter equation in fundamental representations of $c_n$ and thence the full set of $c_n$-invariant factorized $S$-matrices. Brief comments are made on their bootstrap structure and on Belavin's scalar Yangian conserved charges.Comment: 10p

Looking Good With Flickr Faves: Gaussian Processes for Finding Difference Makers in Personality Impressions

Flickr allows its users to generate galleries of "faves", i.e., pictures that they have tagged as favourite. According to recent studies, the faves are predictive of the personality traits that people attribute to Flickr users. This article investigates the phenomenon and shows that faves allow one to predict whether a Flickr user is perceived to be above median or not with respect to each of the Big-Five Traits (accuracy up to 79\% depending on the trait). The classifier - based on Gaussian Processes with a new kernel designed for this work - allows one to identify the visual characteristics of faves that better account for the prediction outcome

Clean-Up after Territorial Oil Spills in the Arctic

… The nature of a spill will depend on the local weather conditions, including the presence or absence of snow, the absorptive capacity of the ground (which is influenced by the prevailing groundwater level), and local topography. … In clean-up operations after oil spills, the first requirement is to contain the spill in as small an area as possible, and to prevent it from reaching water courses and thus contaminating their environments. Devices and techniques can then be employed to remove oil from the contaminated region and convey it to temporary storage. Thirdly, the area can be treated to remove residual oil and promote its early restoration through the use of chemical and biological techniques. … In temperate regions, terrestrial spills are most readily contained by artificial dykes or dams constructed by means of earth-moving equipment, and it is also possible to dig trenches and ditches into which oil will flow and be retained. In areas of permafrost, however, suitable damming material may not be readily available, or may be obtained only if considerable areas of permafrost are exposed - that is, at the cost of additional environmental damage. The use of heavy vehicles, even if they are available, will compact the insulating active layer of permafrost and thereby cause eventual melting of the permafrost. Containment should involve a minimum of disturbance of the area, with no removal or compaction of the active layer and exposure of permafrost. A method of containment which may be feasible is to use damming material that can be quickly transported to the site and installed without the aid of machinery. For example, corrugated metal sheeting in sections about three feet high by ten feet long (1 m x 3 m approximately), with vertical corrugations, could be driven through the active layer down to the water table or frost level or thawed clay soil, all of which provide a basement to vertical oil penetration, and retained in position by T-bar stakes driven into the ground. … The presence of permafrost ironically brings the substantial benefit of there being little of the infiltration of oil into porous soils, with subsequent ground-water contamination, which constitutes such a severe problem in temperate regions; that is, clean-up operations can be facilitated by the presence of permafrost. Another approach to containment, which was tested briefly during the summer of 1974 on wet tundra on Richards Island in the Mackenzie Delta, is to cut a trench, 30 cm wide, to permafrost level across the path of the flowing oil. The trench successfully intercepts the flow of oil, both on and below the surface, and drains it to a low-level point from where it can be pumped to storage or for disposal. … A dam or trench of the type just described, which would necessarily have to be located on the downslope side of the area of spillage, would interfere with natural drainage, and so it would be necessary to control drainage from the area while oil and water were being separated. The present authors suggest that this control could be effected by the installation of an API (American Petroleum Institute) type of oil-water separator which can be constructed easily from prefabricated metal sheeting, usually about 5 feet deep by 10 feet wide by 30 feet long (1.5 m x 3 m x 9 m approximately). … Another possibility would be the use of a compact plate-type oil-water separator. … A significant further advantage of the general technique just explained is the possibility of controlling, and even accelerating, the flow from the area of spillage. … Small-scale laboratory tests have demonstrated that significant proportions of the absorbed oil can be floated out of detritus by gravity alone and without agitation. It is likely that, due to its slow rate of evaporation, the sub-surface oil would maintain a viscosity sufficiently low for it to be floated out by water. It is generally recognized, also, that the toxic constituents of oil are the most volatile and water-soluble. Thus, it is likely that the oil would exhibit toxicity only during the first few months after spillage, and then be permanently absorbed in the vegetation and soil and become immobilized. … As a final stage of restoration of an affected area, it may prove beneficial to fertilize it and promote the growth of oil-degrading microorganisms. Since the albedo of the area will be reduced, and so there will be greater absorption of radiation and increased depth of active layer, it may be desirable to increase the albedo artificially be sprinkling the area with reflective materials. In conclusion, the present authors contend that new techniques must be developed for the clean-up of terrestrial spills in the Arctic, since methods used in temperate regions are inappropriate. &hellip

Prediction of the Atomization Energy of Molecules Using Coulomb Matrix and Atomic Composition in a Bayesian Regularized Neural Networks

Exact calculation of electronic properties of molecules is a fundamental step for intelligent and rational compounds and materials design. The intrinsically graph-like and non-vectorial nature of molecular data generates a unique and challenging machine learning problem. In this paper we embrace a learning from scratch approach where the quantum mechanical electronic properties of molecules are predicted directly from the raw molecular geometry, similar to some recent works. But, unlike these previous endeavors, our study suggests a benefit from combining molecular geometry embedded in the Coulomb matrix with the atomic composition of molecules. Using the new combined features in a Bayesian regularized neural networks, our results improve well-known results from the literature on the QM7 dataset from a mean absolute error of 3.51 kcal/mol down to 3.0 kcal/mol.Comment: Under review ICANN 201

Mechanism of Thermal Decomposition of Lignin

Differential thermal analysis studies of milled wood lignin and lignin carbohydrate complex at different heating rates showed three exothermic peaks. The heating rate is the factor that affects their sharpness and position. The peaks are sharp at low heating rates. Infrared spectra and scanning electron micrographs of the pyrolyzed lignin residues show that aliphatic scission of the lignin molecule at the onset of pyrolysis and progressive carbonization of the surface are the principal features of degradation; there is no intermediate compound formed during the pyrolysis

Studies on the Mechanism of Flame Retardation in Wood

Two lignins, of different carbohydrate content, were pyrolyzed before and after treatment with inorganic salts. Lignin that is relatively free of carbohydrate was inert to the salts: its DTA curve did not change. The DTA curve of lignin associated with about 50% carbohydrate showed a shift of the exothermic peak io a higher temperature and the appearance ofa new exotherm; lithium chloride was the most effective salt in causing this shift. The results support the chemical theory of flame retardation