RCA Satcom 3-Axis spacecraft experience at geosynchronous altitude

The RCA Satcom space segment presently consists of two three-axis stabilized communication satellites which have been in orbit at geosynchronous altitudes for 11 and 8 months respectively. Both satellites have experienced two eclipse seasons since the beginning of operations. Neither spacecraft has exhibited any anomalous behavior that can be attributed to the effects of spacecraft charging. A brief discussion of the history, spacecraft characteristics and design techniques is presented

Mean radiant temperature from global-scale numerical weather prediction models

In human biometeorology, the estimation of mean radiant temperature (MRT) is generally considered challenging. This work presents a general framework to compute the MRT at the global scale for a human subject placed in an outdoor environment and irradiated by solar and thermal radiation both directly and diffusely. The proposed framework requires as input radiation fluxes computed by numerical weather prediction (NWP) models and generates as output gridded globe-wide maps of MRT. It also considers changes in the Sun’s position affecting radiation components when these are stored by NWP models as an accumulated-over-time quantity. The applicability of the framework was demonstrated using NWP reanalysis radiation data from the European Centre for Medium-Range Weather Forecasts. Mapped distributions of MRT were correspondingly computed at the global scale. Comparison against measurements from radiation monitoring stations showed a good agreement with NWP-based MRT (coefficient of determination greater than 0.88; average bias equal to 0.42 °C) suggesting its potential as a proxy for observations in application studies

Speeding up antidynamical Casimir effect with nonstationary qutrits

The antidynamical Casimir effect (ADCE) is a term coined to designate the coherent annihilation of excitations due to resonant external perturbation of system parameters, allowing for extraction of quantum work from nonvacuum states of some field. Originally proposed for a two-level atom (qubit) coupled to a single cavity mode in the context of nonstationary quantum Rabi model, it suffered from very low transition rate and correspondingly narrow resonance linewidth. In this paper we show analytically and numerically that the ADCE rate can be increased by at least one order of magnitude by replacing the qubit by an artificial three-level atom (qutrit) in a properly chosen configuration. For the cavity thermal state we demonstrate that the dynamics of the average photon number and atomic excitation is completely different from the qubit's case, while the behavior of the total number of excitations is qualitatively similar yet significantly faster.Comment: 9 pages, 4 figure

Fractional differentiability for solutions of nonlinear elliptic equations

We study nonlinear elliptic equations in divergence form $${\operatorname{div}}{\mathcal A}(x,Du)={\operatorname{div}}G.$$ When ${\mathcal A}$ has linear growth in $Du$, and assuming that $x\mapsto{\mathcal A}(x,\xi)$ enjoys $B^\alpha_{\frac{n}\alpha, q}$ smoothness, local well-posedness is found in $B^\alpha_{p,q}$ for certain values of $p\in[2,\frac{n}{\alpha})$ and $q\in[1,\infty]$. In the particular case ${\mathcal A}(x,\xi)=A(x)\xi$, $G=0$ and $A\in B^\alpha_{\frac{n}\alpha,q}$, $1\leq q\leq\infty$, we obtain $Du\in B^\alpha_{p,q}$ for each $p<\frac{n}\alpha$. Our main tool in the proof is a more general result, that holds also if ${\mathcal A}$ has growth $s-1$ in $Du$, $2\leq s\leq n$, and asserts local well-posedness in $L^q$ for each $q>s$, provided that $x\mapsto{\mathcal A}(x,\xi)$ satisfies a locally uniform $VMO$ condition

Just For The Hell Of It: A Comparison Of Two Taboo-Term Constructions

The two English constructions exemplified in Let\u27s get the hell out of here (type G) and They beat the hell out of him (type B) differ both syntactically and semantically, but in both the taboo expression has the force of an intensifier. History (through a corpus investigation) reveals that the B-construction started as a literal exorcism (beat the devil out of someone), where the hell substituted for the devil, and semantic bleaching ultimately made the literal sense give way to simple emphasis, with any taboo term jumping in. The G-construction may have developed simultaneously, always as an intensifier--or, perhaps, later, on analogy with B. Our analysis suggests that the use of taboo terms as intensifies spread from wh-constructions to these constructions and, finally, to degree intensifier constructions. These two uses of taboo terms as intensifies are best characterized in terms of constructions and thus offer evidence against theories lacking any notion of constructions as basic building blocks. Further, they give us information about language change: a pragmatically unified but semantically disparate class of expressions (namely, taboo terms) can extend its distribution in parallel

The Good, the Bad, and the News: Twenty Years of the Egyptian Media

The second of two issues, this volume covers aspects of Egyptian society. Contributors include: Donald Cole, Soraya Altorki, Asef Bayat, Eric Denis, Enid Hill, Ziad Bahaeddin, Malak Rouchdy, Linda Herrera, Jim Napoli, Hussein Amin, Mahmoud al-Lozy, Cynthia Nelson, and Shahnaz Rouse.https://fount.aucegypt.edu/faculty_book_chapters/1987/thumbnail.jp

High-performance functional renormalization group calculations for interacting fermions

We derive a novel computational scheme for functional Renormalization Group (fRG) calculations for interacting fermions on 2D lattices. The scheme is based on the exchange parametrization fRG for the two-fermion interaction, with additional insertions of truncated partitions of unity. These insertions decouple the fermionic propagators from the exchange propagators and lead to a separation of the underlying equations. We demonstrate that this separation is numerically advantageous and may pave the way for refined, large-scale computational investigations even in the case of complex multiband systems. Furthermore, on the basis of speedup data gained from our implementation, it is shown that this new variant facilitates efficient calculations on a large number of multi-core CPUs. We apply the scheme to the $t$,$t'$ Hubbard model on a square lattice to analyze the convergence of the results with the bond length of the truncation of the partition of unity. In most parameter areas, a fast convergence can be observed. Finally, we compare to previous results in order to relate our approach to other fRG studies.Comment: 26 pages, 9 figure

Field and numerical study of river confluence flow structures

River hydrodynamicsTurbulent open channel flow and transport phenomen