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Search Results: 1 - 10 of 36 matches for " Quiet "
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Aerodynamic Design of the Bleed Slot in a Hypersonic Quiet Nozzle  [PDF]
Ruiqu Li, Junmou Shen, Feng Ji
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.26053
Abstract:

The bleed slot is necessary for the requirement of the hypersonic quiet flow all over the world. The aim of the bleed slot is to decrease the influence of the disturbances from the contraction of the quiet nozzle to the boundary layer downstream of the throat, so that the boundary layer of the nozzle could be maintained as laminar flow. The main parameters of the bleed slot include the distance from lip to throat (DLT) and the width of slot (WS). Various values of those parameters will affect the performance of the slot by changing the suction intensity of the bleed slot. Two kinds of the bleed slots in the world are compared in this paper and the aerodynamic design of the bleed slots is optimized based on the Purdue-type slot. The influences of the various values of those parameters to the flow field around the throat are analyzed and the optimizing results of DLT and WS are consistent with those relative data designed for the slot of the Boeing/AFOSR Ma 6 Quiet Tunnel.

An Exploratory Survey of Sound Levels in New York City Restaurants and Bars  [PDF]
Gregory Scott
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.68005
Abstract: For several decades, there has been a significant need to better educate the public about noise pollution. A small number of small-scale studies have focused on the sound levels of restaurants and their impact on health and hearing. There have also been an increasing number of media articles stating that eating and drinking venues are getting increasingly loud making it more difficult for people to connect with others in conversation. This study reports on an exploratory large-scale noise survey of sound levels of 2376 restaurants and bars in New York City using a novel smart-phone application and categorized them based on how quiet or loud they were. The results suggest that: 1) A significant number of venues have high sound levels that are not conducive to conversation and may be endangering the health of patrons and employees, 2) that the reported sound levels by the venue managers on their online public business pages generally underestimated actual sound levels, and 3) the average sound levels in restaurants and bars are correlated by neighborhood and type of cuisine.
Do Quiet Areas Afford Greater Health-Related Quality of Life than Noisy Areas?
Daniel Shepherd,David Welch,Kim N. Dirks,David McBride
International Journal of Environmental Research and Public Health , 2013, DOI: 10.3390/ijerph10041284
Abstract: People typically choose to live in quiet areas in order to safeguard their health and wellbeing. However, the benefits of living in quiet areas are relatively understudied compared to the burdens associated with living in noisy areas. Additionally, research is increasingly focusing on the relationship between the human response to noise and measures of health and wellbeing, complementing traditional dose-response approaches, and further elucidating the impact of noise and health by incorporating human factors as mediators and moderators. To further explore the benefits of living in quiet areas, we compared the results of health-related quality of life (HRQOL) questionnaire datasets collected from households in localities differentiated by their soundscapes and population density: noisy city, quiet city, quiet rural, and noisy rural. The dose-response relationships between noise annoyance and HRQOL measures indicated an inverse relationship between the two. Additionally, quiet areas were found to have higher mean HRQOL domain scores than noisy areas. This research further supports the protection of quiet locales and ongoing noise abatement in noisy areas.
Aerodynamic Optimization of the Expansion Section in a Hypersonic Quiet Nozzle Based on Favorable Pressure Effect  [PDF]
Jian Gong, Dapeng Yao, Xunhua Liu
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.26054
Abstract:

Maximum expansion angle is the primary parameter for the design of expansion section of hypersonic quiet nozzle. According to the quantity of maximum expansion angle, expansion section could be classified as fast expansion and slow expansion. In order to diminish the effect of instability of Görtler vortex, gradually, slow expansion was employed for quiet nozzle design. Based on the favorable pressure effect, the maximum expansion angle is optimized in this paper, and a considerable selective session of maximum expansion angle is obtained. The trend that slow expansion is employed instead of fast expansion is explained, and a new method is established for aerodynamic optimization of expansion section contour in a quiet nozzle.

Niveles de progesterona durante el ciclo normal y silencioso en bovinos en el trópico colombiano
Grajales L,Henry; Hernández V,Aureliano; Prieto,Esperanza;
Revista MVZ Córdoba , 2010,
Abstract: objective. determine the sequence of changes in the levels of progesterone (np) during the normal cycle (nc) and quiet cycle (cs). materials and methods. 94 females of the breed holstein x cebu (hc), simmental x cebu (sc), romosinuano (r) and cebu (c) were studied from puberty and during the first three estrous cycles. blood samples were taken to determine concentrations of progesterone by radioimmunoassay, 184 progesterone profiles were determined for cn and 153 for cs. for the analysis of the information the statistical program sas was used. results. the r group presented a pattern of variations of the np through the phases of the cn that has significant differences with the behavior of np in the phases of cn groups sc, hc and c. progesterone levels in each phase of the cs are consistent with a low luteal phase progesterone levels. only significant differences were found in the late luteal phase when comparing cn with cs, however, numerical differences arise at all stages between these two types of cycles. conclusions. progesterone concentrations have a marked effect on the presentation of cs, however, is difficult to define a concentration of progesterone that characterize each event (cn or cs), however, it is clear that progesterone affects the chances to be a favorable or unfavorable reproductive response.
Generating SMS (Short Message Service) in the form of Quick Response Code (QR-code)
Mohammad Zainuddin,D. Baswaraj,SM Riyazoddin
International Journal of Computer Science and Mobile Computing , 2012,
Abstract: This article shows how a QR-code can be generated from a simple sms. We can see lot of QRcodes or mobile barcodes around us on websites, books, gadgets, T-shirts etc. which are making our work easier with just 1 click decode with high speed. With respect to old barcodes, QR-codes are very fast and they can store lot of data, making it more superior. QR-Codes originated within the technology hungry country ofJapan, and have only recently began to become popular within the Middle East and Europe. Barcodes that you see on any commercial product are extremely beneficial as their reading speed, supreme accuracy and their functionalities are main keys. As barcodes reached their peak and began getting used worldwide, the need for more data and character types to be stored was inevitable. Developers began trying to expand on the current amount of bars within the barcode and how their positioning resides to allow further data capacities.The need for smaller barcodes also was another defining factor in QR-Codes development.
Regional study of the ionosphere quietness over Europe
T. L. Gulyaeva,I. Stanislawska
Annals of Geophysics , 1994, DOI: 10.4401/ag-4238
Abstract: Regional catalogues of the ionospherically disturbed and quiet days are developed on the basis of the analysis of vertical-incidence sounding data over European area during 1964-1990. This paper presents the results obtained by comparing and combining two regional catalogues of the ionospheric disturbed and quiet days into one definitive catalogue recommended for implementation in the PRIME oriented and other studies. According to the criteria applied to the F region peak parameters, only 10 to 20% days per year manifest quietness of acceptable level. Comparison of ionospherically quiet days with geomagnetically quiet periods during 1976-1988 shows coincidence of quiet days in both fields not more than 30% of times considered. Conventional practice of analysis of the ionosphere state by comparing it with the geomagnetic conditions should be forerun by specification of the proper ionospheric quiet and disturbed periods.
Quiet Zone Design in Diffuse Fields Using Ultrasonic Transducers  [PDF]
Wen-Kung Tseng
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.32036
Abstract:

This paper presents quiet zone design using ultrasonic transducers for local active control in pure tone diffuse fields. Most of researches in local active noise control used conventional loudspeakers for the secondary sources to produce quiet zones. Recently ultrasonic transducers have been used for the secondary sources to control the plane wave in active noise control. However there is no research related to active noise control in diffuse fields using ultrasonic transducers. Therefore this study uses ultrasonic transducers for the secondary sources to control the diffuse fields. The quiet zone produced using ultrasonic transducers in single tone diffuse fields has been analyzed through simulations in this work. The results showed that quiet zones created using ultrasonic transducers were larger than those created using conventional loudspeakers. This is due to the fact that the audible sound pressure produced by the ultrasonic transducers decays slowly with the distance. Therefore the secondary field created by an ultrasonic transducer could fit the primary field better and the larger zone of quiet could be obtained using the ultrasonic transducer. Also the audible sound produced by the ultrasonic transducers is directional; therefore the sound pressure amplification outside the quiet zones was lower.?

Attractive "Quiet" Courtyards: A Potential Modifier of Urban Residents' Responses to Road Traffic Noise?
Anita Gidl?f-Gunnarsson,Evy ?hrstr?m
International Journal of Environmental Research and Public Health , 2010, DOI: 10.3390/ijerph7093359
Abstract: The present paper explores the influence of the physical environmental qualities of “quiet” courtyards (degree of naturalness and utilization) on residents’ noise responses. A questionnaire study was conducted in urban residential areas with road-traffic noise exposure between L Aeq,24h 58 to 68 dB at the most exposed fa?ade. The dwellings had “quiet” indoor section/s and faced a “quiet” outdoor courtyard (L Aeq,24h < 48 dB fa?ade reflex included). Data were collected from 385 residents and four groups were formed based on sound-level categories (58–62 and 63–68 dB) and classification of the “quiet” courtyards into groups with low and high physical environmental quality. At both sound-level categories, the results indicate that access to high-quality “quiet” courtyards is associated with less noise annoyance and noise-disturbed outdoor activities among the residents. Compared to low-quality “quiet” courtyards, high-quality courtyards can function as an attractive restorative environment providing residents with a positive soundscape, opportunities for rest, relaxation and play as well as social relations that potentially reduce the adverse effects of noise. However, access to quietness and a high-quality courtyard can only compensate partly for high sound levels at fa?ades facing the streets, thus, 16% and 29% were still noise annoyed at 58–62 and 63–68 dB, respectively. Implications of the “quiet”-side concept are discussed.
Valuation of Green Walls and Green Roofs as Soundscape Measures: Including Monetised Amenity Values Together with Noise-attenuation Values in a Cost-benefit Analysis of a Green Wall Affecting Courtyards
Knut Veisten,Yuliya Smyrnova,Ronny Kl?boe,Maarten Hornikx,Marjan Mosslemi,Jian Kang
International Journal of Environmental Research and Public Health , 2012, DOI: 10.3390/ijerph9113770
Abstract: Economic unit values of soundscape/acoustic effects have been based on changes in the number of annoyed persons or on decibel changes. The normal procedure has been the application of these unit values to noise-attenuation measures affecting the noisier fa?ade of a dwelling. Novel modular vegetation-based soundscape measures, so-called green walls, might be relevant for both noisy and quieter areas. Moreover, their benefits will comprise noise attenuation as well as non-acoustic amenity effects. One challenge is to integrate the results of some decades of non-acoustic research on the amenity value of urban greenery into design of the urban sound environment, and incorporate these non-acoustic properties in the overall economic assessment of noise control and overall sound environment improvement measures. Monetised unit values for green walls have been included in two alternative cases, or demonstration projects, of covering the entrances to blocks of flats with a green wall. Since these measures improve the noise environment on the quiet side of the dwellings and courtyards, not the most exposed fa?ade, adjustment factors to the nominal quiet side decibel reductions to arrive at an estimate of the equivalent overall acoustic improvement have been applied. A cost-benefit analysis of the green wall case indicates that this measure is economically promising, when valuing the noise attenuation in the quieter area and adding the amenity/aesthetic value of the green wall.
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