Predicting urban surface roughness aerodynamic parameters using random forest

The surface roughness aerodynamic parameters z0 (roughness length) and d (zero-plane displacement height) are vital to the accuracy of the Monin–Obukhov similarity theory. Deriving improved urban canopy parameterization (UCP) schemes within the conventional framework remains mathematically challenging. The current study explores the potential of a machine-learning (ML) algorithm, a random forest (RF), as a complement to the traditional UCP schemes. Using large-eddy simulation and ensemble sampling, in combination with nonlinear least squares regression of the logarithmic-layer wind profiles, a dataset of approximately 4.5 × 10³ samples is established for the aerodynamic parameters and the morphometric statistics, enabling the training of the ML model. While the prediction for d is not as good as the UCP after Kanda et al., the performance for z₀ is notable. The RF algorithm also categorizes z₀ and d with an exceptional performance score: the overall bell-shaped distributions are well predicted, and the ±0.5σ category (i.e., the 38% percentile) is competently captured (37.8% for z₀ and 36.5% for d). Among the morphometric features, the mean and maximum building heights (Have and Hmax, respectively) are found to be of predominant influence on the prediction of z₀ and d. A perhaps counterintuitive result is the considerably less striking importance of the building-height variability. Possible reasons are discussed. The feature importance scores could be useful for identifying the contributing factors to the surface aerodynamic characteristics. The results may shed some light on the development of ML-based UCP for mesoscale modeling

Effect of Transition Magnetic Moments on Collective Supernova Neutrino Oscillations

We study the effect of Majorana transition magnetic moments on the flavor evolution of neutrinos and antineutrinos inside the core of Type-II supernova explosions. We find non-trivial collective oscillation effects relating neutrinos and antineutrinos of different flavors, even if one restricts the discussion to Majorana transition electromagnetic moment values that are not much larger than those expected from standard model interactions and nonzero neutrino Majorana masses. This appears to be, to the best of our knowledge, the only potentially observable phenomenon sensitive to such small values of Majorana transition magnetic moments. We briefly comment on the effect of Dirac transition magnetic moments and on the consequences of our results for future observations of the flux of neutrinos of different flavors from a nearby supernova explosion.Comment: 11 pages,appendix added, version accepted in JCA

Thermodynamic Limit Of The Ginzburg-Landau Equations

We investigate the existence of a global semiflow for the complex Ginzburg-Landau equation on the space of bounded functions in unbounded domain. This semiflow is proven to exist in dimension 1 and 2 for any parameter values of the standard cubic Ginzburg-Landau equation. In dimension 3 we need some restrictions on the parameters but cover nevertheless some part of the Benjamin-Feijer unstable domain.Comment: uuencoded dvi file (email: [email protected]

Supernova neutrino oscillations: what do we understand?

We summarize our current understanding of the neutrino flavor conversions inside a core collapse supernova, clarifying the important role played by the "collective effects" in determining flavor conversion probabilities. The potentially observable $\nu_e$ and $\bar{\nu}_e$ spectra may help us identify the neutrino mixing scenario, distinguish between primary flux models, and learn more about the supernova explosion.Comment: 6 pages, 1 eps figure, jpconf.cls used. Talk given at TAUP 2009, Rome, July 200

Entanglement purification of multi-mode quantum states

An iterative random procedure is considered allowing an entanglement purification of a class of multi-mode quantum states. In certain cases, a complete purification may be achieved using only a single signal state preparation. A physical implementation based on beam splitter arrays and non-linear elements is suggested. The influence of loss is analyzed in the example of a purification of entangled N-mode coherent states.Comment: 6 pages, 3 eps-figures, using revtex

Enhancing properties of iron and manganese ores as oxygen carriers for chemical looping processes by dry impregnation

The use of naturally occurring ores as oxygen carriers in CLC processes is attractive because of their relative abundance and low cost. Unfortunately, they typically exhibit lower reactivity and lack the mechanical robustness required, when compared to synthetically produced carriers. Impregnation is a suitable method for enhancing both the reactivity and durability of natural ores when used as oxygen carriers for CLC systems. This investigation uses impregnation to improve the chemical and mechanical properties of a Brazilian manganese ore and a Canadian iron ore. The manganese ore was impregnated with Fe2O3 and the iron ore was impregnated with Mn2O3 with the goal of forming a combined Fe/Mn oxygen carrier. The impregnated ore’s physical characteristics were assessed by SEM, BET and XRD analysis. Measurements of the attrition resistance and crushing strength were used to investigate the mechanical robustness of the oxygen carriers. The impregnated ore’s mechanical and physical properties were clearly enhanced by the impregnation method, with boosts in crushing strength of 11–26% and attrition resistance of 37–31% for the impregnated iron and manganese ores, respectively. Both the unmodified and impregnated ore’s reactivity, for the conversion of gaseous fuel (CH4 and syngas) and gaseous oxygen release (CLOU potential) were investigated using a bench-scale quartz fluidised-bed reactor. The impregnated iron ore exhibited a greater degree of syngas conversion compared to the other samples examined. Iron ore based oxygen carrier’s syngas conversion increases with the number of oxidation and reduction cycles performed. The impregnated iron ore exhibited gaseous oxygen release over extended periods in an inert atmosphere and remained at a constant 0.2% O2 concentration by volume at the end of this inert period. This oxygen release would help ensure the efficient use of solid fuels. The impregnated iron ore’s reactivity for CH4 conversion was similar to the reactivity of its unmodified counterpart. The unmodified manganese ore converted CH4 to the greatest extent of all the samples tested here, while the impregnated manganese ore exhibited a decrease in reactivity with respect to syngas and CH4 conversion.EPSR

Purification, Characterization and Antibacterial Mechanism of Bacteriocin from Lactobacillus Acidophilus XH1

Purpose: To carry out the extraction, purification and biological characterization, and assess the antibacterial activity of bacteriocin from Lactobacillus acidophilus XH1.Methods: Chloroform extraction method was used for bacteriocin extraction while characterization of bacteriocin was carried out by flat-dug well agar diffusion assay. The antibacterial mechanisms of bacteriocin were examined by scanning electron microscopy and atomic emission spectroscopy. The molecular weight of lactobacillin XH1 was measured using Tricine - SDS - PAGE electrophoresis.Results: The bacteriocin (lactobacillin XH1) inhibited Escherichia coli, Staphylococcus aureus and Bacillus anthracis. It showed a wide range of antimicrobial activity at pH 1.0 - 5.0 while at 37 – 120 °C, it was sensitive to trypsin, pepsin and papain, but insensitive to proteinase K and neutral protease. The intracellular UV-absorbing substances,, namely, lactate dehydrogenase macromolecules, K+ and ATP of E. coli, decreased rapidly. The molecular weight of lactobacillin XH1 was approximately 16 kDa.Conclusion: Lactobacillin XH1 is a broad-spectrum antimicrobial substance that is thermostable. Its antibacterial mechanism on Escherichia coli is similar to that of bacteriocins on Gram-positive bacteria. The agent is a hydrophobic protein with more acidic groups.Keywords: Lactobacillus acidophilus, Lactobacillin, Bacteriocin, Purification, Antibacterial mechanism, Atomic emission spectroscop

Tripartite to Bipartite Entanglement Transformations and Polynomial Identity Testing

We consider the problem of deciding if a given three-party entangled pure state can be converted, with a non-zero success probability, into a given two-party pure state through local quantum operations and classical communication. We show that this question is equivalent to the well-known computational problem of deciding if a multivariate polynomial is identically zero. Efficient randomized algorithms developed to study the latter can thus be applied to the question of tripartite to bipartite entanglement transformations

Synergistic Effects of Branched-chain Amino Acids and Phenylalanine Addition on Major Volatile Compounds in Wine during Alcoholic Fermentation

The effects of adding branched-chain amino acids (BCAAs, including L-valine, L-leucine and L-isoleucine),L-phenylalanine and a mixture of them (BCAAs + Phe) on the fermentation profiles of wine yeastEC1118 and the production of volatile compounds were investigated in synthetic grape juice. The additionof selected amino acids had no considerable influence on the yeast growth and primary metabolites of thesugars. Adding BCAAs increased the production of higher alcohols, medium-chain fatty acids (MCFAs)and their corresponding ethyl esters. In comparison, adding Phe promoted the production of 2-phenylethanol,2-phenylethyl acetate and ethyl esters of MCFAs. Nevertheless, the supplementation of BCAAs +Phe further heightened the production of MCFAs, acetate esters and ethyl esters of MCFAs compared tothe single additions, but it attenuated the production of various higher alcohols (1-propanol, 2,3-butanedioland methionol) compared to the addition of BCAAs, and of 2-phenylethanol and 2-phenylethyl acetatecontents compared to the Phe addition. These results suggest that adding BCAAs or Phe is an efficient wayto adjust wine’s aromatic composition and complexity. Meanwhile, the combined addition of BCAAs + Phecould be a potential tool to further manipulate wine’s aromatic profile by accentuating or suppressing theformation of certain aroma compounds