A research to reduce interior noise in general aviation airplanes. General aviation interior noise study

The construction, calibration, and properties of a facility for measuring sound transmission through aircraft type panels are described along with the theoretical and empirical methods used. Topics discussed include typical noise source, sound transmission path, and acoustic cabin properties and their effect on interior noise. Experimental results show an average sound transmission loss in the mass controlled frequency region comparable to theoretical predictions. The results also verify that transmission losses in the stiffness controlled region directly depend on the fundamental frequency of the panel. Experimental and theoretical results indicate that increases in this frequency, and consequently in transmission loss, can be achieved by applying pressure differentials across the specimen

A research program to reduce interior noise in general aviation airplanes. Design of an acoustic panel test facility

The design, construction, and costs of a test facility for determining the sound transmission loss characteristics of various panels and panel treatments are described. The pressurization system and electronic equipment used in experimental testing are discussed as well as the reliability of the facility and the data gathered. Tests results are compared to pertinent acoustical theories for panel behavior and minor anomalies in the data are examined. A method for predicting panel behavior in the stiffness region is also presented

Circuit QED with a Flux Qubit Strongly Coupled to a Coplanar Transmission Line Resonator

We propose a scheme for circuit quantum electrodynamics with a superconducting flux-qubit coupled to a high-Q coplanar resonator. Assuming realistic circuit parameters we predict that it is possible to reach the strong coupling regime. Routes to metrological applications, such as single photon generation and quantum non-demolition measurements are discussed.Comment: 8 pages, 5 figure

The Impacts on Terrestrial Astronomy from Very Low Earth Orbit Telecommunications Constellations

This presented work assesses the potential benefits to terrestrial astronomy through the deployment of telecommunications spacecraft into lower orbits. Results show that by operating closer to the user in Very Low Earth Orbits (VLEO) the illumination of a constellation rapidly reduces and the scientifically useful operational time at key locations is greatly increased.In recent years the exponential growth in Low Earth Orbit (LEO) constellations has caused concern to the astronomical community, primarily due to the increase in broadband internet provision through the Starlink satellite network. A range of novel services are being enabled by these constellations to great public benefit and of future commercial interest is the extension of terrestrial mobile capabilities through non-terrestrial networks delivering direct-to-device connectivity to low power handsets. Some current delivery plans rely on large surface area phased arrays such as the BlueWalker3 prototype. This deployed a 64 square metre antenna at an orbit of 510 km and was observed at a 0.4 peak V-band apparent magnitude, making it one of the brightest night sky objects and impacting terrestrial observations when transiting the field of view. This is a precursor to a 243-spacecraft constellation at 725 – 740 km that may increase in brightness and display longer periods of visibility.A possible mitigation against these astronomical impacts may be obtained by operating constellations in VLEO. Developments in erosion resistant and drag reducing materials, along with advances in traditional and atmosphere breathing electric propulsion have begun to open this orbital regime and current applications have generally focused on Earth Observation (EO). However, reductions in power and latency due to shorter transmission distances, access to higher frequencies and data rates from reduced path loss, and eased demands on spacecraft components due to the benign radiation environment all present opportunities in the delivery of high speed, low latency, ubiquitous global telecommunications and may be particularly beneficial for direct-to-device services.This paper describes analytical models representing constellations across a range of altitudes and compares the impact on the operational performance of optical astronomy facilities at three representative locations. Analysis shows that lower constellations maximise the satellite free observational time during astronomical night with only a 0.3 - 4.6% loss due to a satellite constellation orbiting at 250 km with the greatest benefit at lower latitudes, compared to 21.4 - 35% degradation at 550 km and 56.5 - 67.2% of fully operational observation time impacted at an altitude of 1150 km.<br/

Optimizing Doppler Surveys for Planet Yield

One of the most promising methods of discovering nearby, low-mass planets in the habitable zones of stars is the precision radial velocity technique. However, there are many challenges that must be overcome to efficiently detect low-amplitude Doppler signals. This is both due to the required instrumental sensitivity and the limited amount of observing time. In this article, we examine statistical and instrumental effects on precision radial velocity detection of extrasolar planets, an approach by which we maximize the planet yield in a fixed amount of observing time available on a given telescope. From this perspective, we show that G and K dwarfs observed at 400–600 nm are the best targets for surveys complete down to a given planet mass and out to a specified orbital period. Overall we find that M dwarfs observed at 700–800 nm are the best targets for habitable-zone planets, particularly when including the effects of systematic noise floors. Also, we give quantitative specifications of the instrumental stability necessary to achieve the required velocity precision

Quantum Phase Transitions in Anti-ferromagnetic Planar Cubic Lattices

Motivated by its relation to an $\cal{NP}$-hard problem, we analyze the ground state properties of anti-ferromagnetic Ising-spin networks embedded on planar cubic lattices, under the action of homogeneous transverse and longitudinal magnetic fields. This model exhibits a quantum phase transition at critical values of the magnetic field, which can be identified by the entanglement behavior, as well as by a Majorization analysis. The scaling of the entanglement in the critical region is in agreement with the area law, indicating that even simple systems can support large amounts of quantum correlations. We study the scaling behavior of low-lying energy gaps for a restricted set of geometries, and find that even in this simplified case, it is impossible to predict the asymptotic behavior, with the data allowing equally good fits to exponential and power law decays. We can therefore, draw no conclusion as to the algorithmic complexity of a quantum adiabatic ground-state search for the system.Comment: 7 pages, 13 figures, final version (accepted for publication in PRA

Physical interpretation of the Wigner rotations and its implications for relativistic quantum information

We present a new treatment for the spin of a massive relativistic particle in the context of quantum information based on a physical interpretation of the Wigner rotations, obtaining different results in relation to the previous works. We are lead to the conclusions that it is not possible to define a reduced density matrix for the particle spin and that the Pauli-Lubanski (or similar) spin operators are not suitable to describe measurements where spin couples to an electromagnetic field in the measuring apparatus. These conclusions contradict the assumptions made by most of the previous papers on the subject. We also propose an experimental test of our formulation.Comment: 10 pages, 2 figures. Several changes were made on the text. One extra example was include

The sharp phase transition for level set percolation of smooth planar Gaussian fields

Version accepted for publication. 36 pages, 3 figuresWe prove that the connectivity of the level sets of a wide class of smooth centred planar Gaussian fields exhibits a phase transition at the zero level that is analogous to the phase transition in Bernoulli percolation. In addition to symmetry, positivity and regularity conditions, we assume only that correlations decay polynomially with exponent larger than two -- roughly equivalent to the integrability of the covariance kernel -- whereas previously the phase transition was only known in the case of the Bargmann-Fock covariance kernel which decays super-exponentially. We also prove that the phase transition is sharp, demonstrating, without any further assumption on the decay of correlations, that in the sub-critical regime crossing probabilities decay exponentially. Key to our methods is the white-noise representation of a Gaussian field; we use this on the one hand to prove new quasi-independence results, inspired by the notion of influence from Boolean functions, and on the other hand to establish sharp thresholds via the OSSS inequality for i.i.d. random variables, following the recent approach of Duminil-Copin, Raoufi and Tassion

Conformal Partial Waves and the Operator Product Expansion

By solving the two variable differential equations which arise from finding the eigenfunctions for the Casimir operator for $O(d,2)$ succinct expressions are found for the functions, conformal partial waves, representing the contribution of an operator of arbitrary scale dimension $\Delta$ and spin $\ell$ together with its descendants to conformal four point functions for $d=4$, recovering old results, and also for $d=6$. The results are expressed in terms of ordinary hypergeometric functions of variables $x,z$ which are simply related to the usual conformal invariants. An expression for the conformal partial wave amplitude valid for any dimension is also found in terms of a sum over two variable symmetric Jack polynomials which is used to derive relations for the conformal partial waves.Comment: 17 pages, uses harvmac, v2 correction to eq. 2.2