On the VLBI measurement of the Solar System acceleration

We propose new estimates of the secular aberration drift, mainly due to the rotation of the Solar System about the Galactic center, based on up-to-date VLBI observations and and improved method of outlier elimination. We fit degree-2 vector spherical harmonics to extragalactic radio source proper motion field derived from geodetic VLBI observations spanning 1979-2013. We pay particular attention to the outlier elimination procedure to remove outliers from (i) radio source coordinate time series and (ii) the proper motion sample. We obtain more accurate values of the Solar system acceleration compared to those in our previous paper. The acceleration vector is oriented towards the Galactic center within 7 deg. The component perpendicular to the Galactic plane is statistically insignificant. We show that an insufficient cleaning of the data set can lead to strong variations in the dipole amplitude and orientation, and statistically biased results.Comment: Accepted for publication in A&

Demonstration of a sterilizable solid rocket motor system, addendum

Technical emphasis was placed on characterization of a scaled-up batch of the improved propellant formulation and determination of the effects of dry heat sterilization on propellant integrity and structural response. The grain stress analysis was directed toward tailoring a fully-bonded grain to the calculated propellant allowable stresses and investigating various bond release concepts to relieve stresses incurred in thermal shrinkage following sterilization

Sperm whales from the Miocene of the North Sea: a re-appraisal

A review of the sperm whales (Cetacea, Odontoceti, Physeteroidea) from the Miocene of the southern margin of the North Sea Basin is undertaken, mostly based on the cranial material of the area of Antwerp (north of Belgium) described for the first time by P.-J. Van Beneden, B. A. L. du Bus, and O. Abel more than a century ago. This work leads to the detailed redescription of the species Eudelphis mortezelensis, Physeterula dubusi, Placoziphius duboisi, and Thalassocetus antwerpiensis, the identification in the North Sea Basin of the eastern North American species Orycterocetus crocodilinus, and the description of a new undetermined physeterid. The stratigraphic information associated to some of these Miocene taxa is refined (E. mortezelensis, O. crocodilinus, and P. duboisi), whereas a more important incertitude persists for others. These results further emphasize the physeteroid diversity during the Miocene. The performed phylogenetic analysis places Eudelphis as the most basal stem-physeteroid, displaying the most salient features of the superfamily (supracranial basin, strong asymmetry of the bony nares and premaxillae) but retaining enamel on teeth and a rather conservative skull morphology (deep maxillary alveoli, large left pre-maxillary foramen, distinct falciform process of the squamosal...). Together with Orycterocetus, Placoziphius is provisionally kept outside the family Physeteridae, defined as the clade grouping all the physeteroids more closely related to Physeter than to Kogia. The large species Physeterula dubusi is the most stemward physeterid, retaining functional upper teeth lacking enamel. Among the physeterids the new undetermined taxon is sister-group to the clade Aulophyseter + Physeter, sharing with these two genera the preorbital process distinctly lower than the lateral margin of the rostrum base. With a sagittal crest in its supracranial basin the small Thalassocetus antwerpiensis is confirmed as an archaic kogiid. The evolutionary history of the supracranial basin and the oral apparatus are discussed. The parsimony analysis suggests that the spermaceti organ remained small in the supracranial basin of most physeteroids, the basin probably functioning as a parabolic structure for reflecting and focusing the echolocative sounds. It is proposed that the spermaceti organ only considerable increased in size in the lineage of the Recent species Physeter macrocephalus, possibly as a sexually dimorphic sound transmitting organ. Preceded by the loss of enamel, the reduction of the upper dentition associated to a decrease of the size of the temporal fossa occurred in parallel in the physeterids and the kogiids, much likely related to a major change in diet and food processing

Application of the ONERA model of dynamic stall

A semiempirical model to predict the unsteady loads on an airfoil that is experiencing dynamic stall, is investigated. The mathematical model is described from an engineering point of view, demonstrates the procedure for obtaining various empirical parameters, and compares the loads predicted by the model with those obtained in the experiment. It is found that the procedure is straightforward, and the final calculations are in qualitative agreement with the experimental results. Comparisons between calculations and measurements also indicate that a decrease in accuracy results when the values of both the reduced frequency and the amplitude of oscillation are large. Potential quantitative improvements in the accuracy of the calculations are discussed for accounting of both the hysteresis in the static data and the effects of stall delay in the governing equations

Deconstructing (2,0) proposals

C. P. is supported by the U.S. Department of Energy under Grant No. DE-FG02-96ER40959. M. S. S. is supported by an EURYI award of the European Science Foundatio

Roman Catholicism Un-American

https://digitalcommons.acu.edu/crs_books/1267/thumbnail.jp

Preliminary Investigation into Modeling The Damage to Carbon Fibre Composites Due to the Thermo-electric Effects of a Lightning Strikes

The impact of a lightning strike causes a short high electrical current burst through Carbon Fibre Composites (CFC). Due to the electrical properties of CFC the large current leads to a rapid heating of the surrounding impact area which degrades and damages the CFC. It is therefore necessary to study in detail the thermal response and possible degradation processes caused to CFC. The degradation takes place in two ways, firstly via direct mechanical fracture due to the thermal expansion of the CFC and secondly via thermo-chemical processes (phase change and pyrolysis) at high temperatures. The main objective of this work is to construct a numerical model of the major physical processes involved, and to understand the correlation between the damage mechanisms and the damage witnessed in modern CFC. For this work we are only considering the thermo-chemical degradation of CFC. Bespoke numerical models have been constructed to predict the extent of the damage caused by the two thermo-chemical processes separately (e.g. a model for phase change and a model for pyrolysis). The numerical model predictions have then been verified experimental by decoupling of the damage mechanisms, e.g. the real Joule heating from a lightning strike is replaced by a high power laser beam acting on composite surface. This was done to simplify the physical processes which occur when a sample is damaged. The experimentally damaged samples were then investigated using X-ray tomography to determine the physical extent of the damage. The experimental results are then compared with the numerical predictions by considering the physical extent of the polymer removal. The extent of polymer removal predicted by the numerical model, solving for pyrolysis, gave a reasonable agreement with the damage seen in the experimental sample. Furthermore the numerical model predicts that the damage caused by polymer phase change has a minimal contribution to the overall extent of the damage

Relating U(N)xU(N) to SU(N)xSU(N) Chern-Simons Membrane theories

By integrating out the U(1)_B gauge field, we show that the U(n)xU(n) ABJM theory at level k is equivalent to a Z_k identification of the (SU(n)xSU(n))/Z_n Chern-Simons theory, but only when n and k are coprime. As a consequence, the k=1 ABJM model for two M2-branes in R^8 can be identified with the N=8 (SU(2)xSU(2))/Z_2 theory. We also conjecture that the U(2)xU(2) ABJM model at k=2 is equivalent to the N=8 SU(2)xSU(2)-theory.Comment: 16 pages, Latex; v2: references added; v3: Clarifications adde

Unified single-photon and single-electron counting statistics: from cavity-QED to electron transport

A key ingredient of cavity quantum-electrodynamics (QED) is the coupling between the discrete energy levels of an atom and photons in a single-mode cavity. The addition of periodic ultra-short laser pulses allows one to use such a system as a source of single photons; a vital ingredient in quantum information and optical computing schemes. Here, we analyze and ``time-adjust'' the photon-counting statistics of such a single-photon source, and show that the photon statistics can be described by a simple `transport-like' non-equilibrium model. We then show that there is a one-to-one correspondence of this model to that of non-equilibrium transport of electrons through a double quantum dot nanostructure. Then we prove that the statistics of the tunnelling electrons is equivalent to the statistics of the emitted photons. This represents a unification of the fields of photon counting statistics and electron transport statistics. This correspondence empowers us to adapt several tools previously used for detecting quantum behavior in electron transport systems (e.g., super-Poissonian shot noise, and an extension of the Leggett-Garg inequality) to single-photon-source experiments.Comment: 8 pages, 3 figure