The noise environment of a school classroom due to the operation of utility helicopters

Noise measurements under controlled conditions have been made inside and outside of a school building during flyover operations of four different helicopters. The helicopters were operated at a condition considered typical for a police patrol mission. Flyovers were made at an altitude of 500 ft and an airspeed of 45 miles per hour. During these operations acoustic measurements were made inside and outside of the school building with the windows closed and then open. The outside noise measurements during helicopter flyovers indicate that the outside db(A) levels were approximately the same for all test helicopters. For the windows closed case, significant reductions for the inside measured db(A) values were noted for all overflights. These reductions were approximately 20 db(A); similar reductions were noted in other subjective measuring units. The measured internal db(A) levels with the windows open exceeded published classroom noise criteria values; however, for the windows-closed case they are in general agreement with the criteria values

On the measure of nonclassicality of field states

The degree of nonclassicality of states of a field mode is analysed considering both phase-space and distance-type measures of nonclassicality. By working out some general examples, it is shown explicitly that the phase-space measure is rather sensitive to superposition of states, with finite superpositions possessing maximum nonclassical depth (the highest degree of nonclassicality) irrespective to the nature of the component states. Mixed states are also discussed and examples with nonclassical depth varying between the minimum and the maximum allowed values are exhibited. For pure Gaussian states, it is demonstrated that distance-type measures based on the Hilbert-Schmidt metric are equivalent to the phase-space measure. Analyzing some examples, it is shown that distance-type measures are efficient to quantify the degree of nonclassicality of non-Gaussian pure states.Comment: Latex, 21 pages, 1 figur

Cross section for the photodetachment of Be-

[[abstract]]The cross section for single-photon detachment of an electron from the metastable Be- ion has been measured at a photon energy of 2.076 eV to be 31±3 Mb. The method of laser photodetached electron spectroscopy was used in the measurement and the asymmetry parameter that characterizes the angular distribution of the detached photoelectrons was also measured to be β=0.49±0.02 at the same energy.[[incitationindex]]SCI[[booktype]]紙

Geological Mapping of the Debussy Quadrangle (H-14) Preliminary Results

Geological mapping of Mercury is crucial to build an understanding of the history of the planet and to set the context for BepiColombo’s observations [1]. Geo-logical mapping of the Debussy quadrangle (H-14) is now underway as part of a program to map the entire planet at a scale of 1:3M using MESSENGER data [2]. The quadrangle is located in the southern hemisphere of Mercury at 0o – 90o E and 22.5o – 65o S. This will be the first high resolution map of the quadrangle as it was not imaged by Mariner 10

Results of the flight noise measurement program using a standard and modified SH-3A helicopter

A field noise measurement program has been conducted using both a standard SH-3A helicopter and an SH-3A helicopter modified to reduce external noise levels. Modifications included reducing rotor speed, increasing the number of rotor blades, modifying the blade-tip shapes, and acoustically treating the engine air intakes and exhaust. The purpose of this study was to document the noise characteristics recorded on the ground of each helicopter during flyby, hover, landing, and take-off operations. Based on an analysis of the measured results, the average of the overhead, overall, ontrack noise levels was approximately 4 db lower for the modified helicopter than for the standard helicopter. The improved in-flight noise characteristics, and associated small footprint areas and time durations, were judged to be mainly due to tail-rotor noise reductions. The noise reductions were obtained at the expense of required power increases at airspeeds greater than 70 knots for the modified helicopter

Flyover noise characteristics of a tilt-wing V/STOL aircraft (XC-142A)

A field noise measurement investigation was conducted during the flight testing of an XC-142A tilt-wing V/STOL aircraft to define its external noise characteristics. Measured time histories of overall sound pressure level show that noise levels are higher at lower airspeeds and decrease with increased speed up to approximately 160 knots. The primary noise sources were the four high-speed, main propellers. Flyover-noise time histories calculated by existing techniques for propeller noise prediction are in reasonable agreement with the experimental data

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 5: Combined gas-steam turbine cycles

The energy conversion efficiency of gas-steam turbine cycles was investigated for selected combined cycle power plants. Results indicate that it is possible for combined cycle gas-steam turbine power plants to have efficiencies several point higher than conventional steam plants. Induction of low pressure steam into the steam turbine is shown to improve the plant efficiency. Post firing of the boiler of a high temperature combined cycle plant is found to increase net power but to worsen efficiency. A gas turbine pressure ratio of 12 to 1 was found to be close to optimum at all gas turbine inlet temperatures that were studied. The coal using combined cycle plant with an integrated low-Btu gasifier was calculated to have a plant efficiency of 43.6%, a capitalization of $497/kW, and a cost of electricity of 6.75 mills/MJ (24.3 mills/kwh). This combined cycle plant should be considered for base load power generation

The fundamental cycle of concept construction underlying various theoretical frameworks

In this paper, the development of mathematical concepts over time is considered. Particular reference is given to the shifting of attention from step-by-step procedures that are performed in time, to symbolism that can be manipulated as mental entities on paper and in the mind. The development is analysed using different theoretical perspectives, including the SOLO model and various theories of concept construction to reveal a fundamental cycle underlying the building of concepts that features widely in different ways of thinking that occurs throughout mathematical learning

Schwinger, Pegg and Barnett and a relationship between angular and Cartesian quantum descriptions

From a development of an original idea due to Schwinger, it is shown that it is possible to recover, from the quantum description of a degree of freedom characterized by a finite number of states (\QTR{it}{i.e}., without classical counterpart) the usual canonical variables of position/momentum \QTR{it}{and} angle/angular momentum, relating, maybe surprisingly, the first as a limit of the later.Comment: 7 pages, revised version, to appear on J. Phys. A: Math and Ge

The asymmetry of Nathair Facula: A volcanologic mystery on Mercury

[Introduction] Nathair Facula is the largest and most spectrally-distinct of nearly 200 ‘bright red’ spots on Mercury’s surface, most of which are accepted to be deposits from explosive volcanic eruptions. Like most of Mercury’s faculae, it hosts a central pit (in this case about 40 km wide and over 3 km deep). However the centre of this facula does not coincide with the vent, but is displaced about 20 km northwards. This poses as-yet unresolved questions about the nature of the eruption mechanism. Furthermore, the vent area is almost certainly a ‘compound vent’ (Pegg et al., 2019) within which the locus of eruption has migrated between eruptive episodes, and it is unclear how the same asymmetry could be repeatedly en-gendered and reinforced by a series of eruptions rather than averaging out to a symmetrical distribution