Evidence for spatially variable friction from tidal amplification and asymmetry in the Pertuis Breton (France)

The semi-diurnal tides are amplified and distorted as they propagate into the Pertuis Breton, a semi-enclosed shallow basin in the north-eastern part of Bay of Biscay, in France. This paper investigates the influence of bottom friction on amplification and phase lag of the tidal constituent M2 and its overtide M4 in the Pertuis Breton. A fine resolution two-dimensional (2D) numerical model is implemented to simulate tidal propagation. The model solves the depth-averaged shallow-water equations on a finite element grid using the TELEMAC 2D software. A two-zone parameterisation of friction coefficient is introduced to evaluate the impact of smooth mud flats on the tidal asymmetry and amplification in the Pertuis. Fitting the model to observed amplitudes and phases of M2 and M4 evaluates the decrease of Chezy friction coefficient from the mud flats to the rest of the Pertuis as 100:60. This conclusion is supported by the direct estimation based on morphology and composition of sea bed in the Pertuis Breton.     

Open source magnetic inversion programming framework and its practical applications

An Open Source C++ inversion framework for magnetic interpretation, including UXO applications, has been developed. The point dipole model is used to approximate a small magnetic object. However, alternative object models can be easily accommodated. Input data can be presented in a variety of formats and physical units including, but not limited to, profiles of the total magnetic field, uniform data grids, random data points, magnetic gradients, and finite magnetic difference measurements. Well-established external numerical optimization software modules such as the SLATEC (Common Mathematical Library, Los Alamos National Laboratory) package are used to solve numerical problems. Other software modules can easily be incorporated as they become available. Some practical examples of the application of the framework using total field data and vertical total field gradient data from a UXO test range are presented. We have decided to “open-source” the toolkit. It can be downloaded without charge under GNU Public License via anonymous FTP from ftp://geom.geometrics.com/pub/mag/Software/magtoolkit-1.0.zip.     

Colour variations with phase of selected regions of the lunar surface

The four colour photometric observations of 15 regions of the lunar surface are reported in this paper. They all confirm the reddening with increasing phase. Observed regions at wide range of phase show an appreciable colour opposition effect. Reddening factors obtained, are larger near full Moon, and smaller at larger phase angles.     

Optimization of ice cuttings transportation by cable-suspended core auger drills

Ice cores contain an abundance of information about the Earth''s climate in the past,and recovered from shallow drilling down to 300--350 m give sufficient information for reconstructing of the last climatic chan- ges and for monitoring of pollution from human being． Cable-suspended core auger drills use an armored cable with a winch to provide power to the down-hole motor system and to retrieve the down-hole unit． Because of their lightweight,convenient transportation and installation,high penetration rates and low power consumption, core auger drills are widely used for shallow drilling in ice． Nowadays at least 14 types of auger electromechani- cal drills were designed and tested in different foreign and national glaciological laboratories． However,auger options were usually determined by experience,and the main parameters (helix angle of the fights and rotational speed) are varied in a wide range from drill to drill． If parameters of auger are not chosen properly,poorly en- gineered drills had troubles with low efficiency of cuttings transportation,jam of ice cuttings,repeated fragmen- tation,cutters icing and stop penetration,abnormal power consumption,high rotation torques,and so on． Thus,this paper presents the method of optimization of ice cuttings transportation of cable-suspended core auger drill on the base of the theory of rotary auger． As the result,the optimal helix angle was determined correspond- ing to the rotational speed from the transportation efficiency point of view．     

Satellite image retrieval using low memory locality sensitive hashing in Euclidean space

This paper presents the use of the Low Memory Locality Sensitive Hashing (LMLSH) technique operating in Euclidean space to build a data structure for the Defense Meteorological Satellite Program (DMSP) satellite imagery database. The LMLSH technique finds satellite image matches in sublinear search time. The texture feature vectors of the images are extracted using pyramid-structured wavelet transform coupled with Gaussian central moment technique. These feature vectors and families of hash functions, drawn randomly and independently from a Gaussian distribution, are used to build hash tables. Given a query, the hash tables are used to pull out the best matches to that query and this is done in a sublinear search time complexity. When tested, our algorithm has proven to be approximately twenty six times faster than the Linear Search (LS) algorithm. In addition, the LMLSH algorithm searches about two percent of the entire database randomly to find the possible matches to any given query without loss of accuracy compared to the absolute best matches returned by its LS counterpart.     

Hydrogen penetration in water through porous medium: application to a radioactive waste storage site

Hydrogen penetration in water through porous medium was analyzed in the paper. A two-phase compositional model approach was considered. The first part of the work deals with the thermodynamic analysis of the hydrogen–water system. The thermodynamic model was calibrated using the experimental data of hydrogen solubility in water. The phase densities, viscosities and phase concentrations were presented in an analytical form. Moreover, the domain of validity of analytical laws—such as Henry’s, Raoult’s and Kelvin’s laws—for the estimation of phase properties was presented for the analyzed system. The second part deals with two-phase hydrodynamic behaviors. An analytical solution for the non-compressible flow was constructed. In general case, the influence of relative permeabilities on the flow regimes was analyzed numerically. The notion pseudo-saturation was introduced to define phase appearance. Actually, mobile gas created a time displaced front relatively slower than mobile gas flow. Diffusion becomes really important for low mobile gas case as the penetration accelerates for the large range of saturation. In contrast, the mass exchange phenomena have a small influence on the flow type. Thus, the regimes of hydrogen penetration in liquid were shown really sensitive to the relative permeability form.     

The Soviet ASTRON mission: legacy

2013 marks the 30th anniversary since the launch of Soviet Spacecraft Astron that had been operated for 6 years as the largest ultraviolet telescope during its lifetime. The Astron orbital station was designed for the astrophysical observations. It was launched into orbit by Proton launch system on March 23, 1983. Astron had a 80 cm ultraviolet telescope with mass of 400 kg and a complex of X-ray spectrographs with mass of 300 kg on board as a payload. It’s high apogee orbit (with apogee 200000 km and perigee 2000 km) permitted the influences of the Earth’s umbra and radiation belts to be excluded from the measurements. The main astrophysical results are summarized in this paper.     

The condensation origin of zoned metal grains in Queen Alexandra Range 94411: Implications for the formation of the Bencubbin‐like chondrites

Abstract— Thermodynamic analysis of the compositional profiles across large chemically‐zoned Fe, Ni metal grains in the Bencubbin‐like chondrite Queen Alexandra Range (QUE) 94411 suggests that these grains formed by non‐equilibrium gas‐solid condensation under variable oxidizing conditions, isolation degree, and Cr depletion factors. The oxidizing conditions must have resulted from the complete vaporization of nebular regions with enhanced dust/gas ratios (～ 10–40 × solar). Because the origin of each of the metal grains studied requires different condensation parameters (dust/gas ratio, isolation degree, and Cr depletion factor), a high degree of heterogeneity in the formation region of the Bencubbin‐like chondrite metal is required. To preserve compositional zoning of the metal grains and prevent their melting and sulfidization, the grains must have been removed from the hot condensation region into cold regions where the accretion of the Bencubbin‐like asteroidal body took place.