3,104 research outputs found
SEA analysis in the cabin of a regional turboprop with metamaterial lining panels
The main goal of this paper is to evaluate the comfort, and hence the interior sound pressure
levels, in the cabin of a regional turboprop with metamaterial lining panels under Turbulent
Boundary Layer flow over the fuselage during cruise flight conditions. In the preliminary
work phase, the design of metamaterial and a numerical analysis at component level were
performed. Then, the CAD model of the fuselage was created representing the typical features
and dimensions of an airplane for regional flights and a Statistical Energy Analysis (SEA) model
was built by using Va One software. An investigation on the influence of designed metamaterial
on the soundproofing of the cabin was presented. Results reveal a reduction in Sound Pressure
Level (SPL) of almost 5 dB with respect to classical materials, in overall the frequency range
and for all the cavities analyzed, in the configuration with metamaterial applied as core of the
sandwich lining panels
Documentary Research and Archaeological Investigations at the Waite-Kirby-Potter Site, Westport, Massachusetts
Research on the Waite-Kirby-Potter house in Westport, Massachusetts, included mapping historical resources visible on the surface and excavating 25 test pits and units near the house foundations in the fall of 2009. Field investigations were complemented by extensive documentary research including a complete chain of title and genealogical research on the three families who have owned the property between the late 17th century and the present. The visible historical features include elements associated with the former stone ender (the standing stone end and chimney, an adjacent brick chimney, and a stone-lined cellar hole), stone walls, a 19th-century barn foundation, a family cemetery, and the standing Restcome Potter house. The excavations uncovered a clean gravel work yard in front of the stone end house and sheet trash scatters with artifacts from the mid-18th to early 20th centuries behind and west of the house, as well as the remains of post holes for an agricultural outbuilding or fence at the edge of the near-by agricultural field. A primary trash deposit from a space within the chimney complex was probably deposited c. 1860 and contained numerous reconstructable ceramic vessels and glass bottles. Several of the ceramic vessels date to the previous century and had been curated for some time before being discarded.
The most significant contributions are to the architectural history of the property; the combination of archaeological and documentary research has suggested some new or more specific dates for events previously dated only by tradition. We suggest that the stone-end house, traditionally dated to 1677, may have been constructed in the early 18th century between 1707 and 1721 by Thomas or Benjamin Waite. The western addition to the house, attributed to David Kirby, was constructed during the period when David and his father Ichabodâs families both occupied the house (1763-1793). The construction of the Restcome Potter house has traditionally been attributed to Restcome in 1838, but the propertyâs previous owner David Kirby mentions his ânew dwelling houseâ in his 1832 will, pushing the construction date of this house earlier. Finally, the modifications to the stone chimney took place after 1858, demonstrating the Potter familyâs continued use and upkeep of the older house. Test pits around the foundations of the western addition to the stone ender uncovered stone foundations and sill supports intact immediately beneath the modern ground surface
Endogenous Gonadal Hormone Exposure and Bone Sarcoma Risk
Although experimental and clinical evidence suggest that endogenous sex hormones influence bone sarcoma genesis, the hypothesis has not been adequately tested in an appropriate animal model. We conducted a historical cohort study of Rottweiler dogs because they frequently undergo elective gonadectomy and spontaneously develop appendicular bone sarcomas, which mimic the biological behavior of the osteosarcomas that affect children and adolescents. Data were collected by questionnaire from owners of 683 Rottweiler dogs living in North America. To determine whether there was an association between endogenous sex hormones and risk of bone sarcoma, relative risk (RR) of incidence rates and hazard ratios for bone sarcoma were calculated for dogs subdivided on the basis of lifetime gonadal hormone exposure. Bone sarcoma was diagnosed in 12.6% of dogs in this cohort during 71,004 dog-months follow-up. Risk for bone sarcoma was significantly influenced by age at gonadectomy. Male and female dogs that underwent gonadectomy before 1 year of age had an approximate one in four lifetime risk for bone sarcoma and were significantly more likely to develop bone sarcoma than dogs that were sexually intact [RR ±95% CI = 3.8 (1.5â9.2) for males; RR ±95% CI = 3.1 (1.1â8.3) for females]. Ï2 test for trend showed a highly significant inverse dose-response relationship between duration of lifetime gonadal exposure and incidence rate of bone sarcoma (P = 0.008 for males, P = 0.006 for females). This association was independent of adult height or body weight. We conclude that the subset of Rottweiler dogs that undergo early gonadectomy represent a unique, highly accessible target population to further study the gene:environment interactions that determine bone sarcoma risk and to test whether interventions can inhibit the spontaneous development of bone sarcoma
Internet fragmentation, political structuring, and organizational concentration in transnational engineering networks
Is the internet at risk of fragmentation? Whereas the literature has examined this question with a focus on domestic policies, communication standards, and internet governance institutions, we analyze fragmentation and alternative outcomes in transnational engineering networks. These networks constitute the social foundations of the unified or âglobalâinternet. Our contributions include (1) broadening the debate beyond fragmentation-related network outcomes to include political structuring and organizational concentration, and (2) new evidence from an important engineering network around the Internet Engineering Task Force comprising thousands of participants and over four decades. Our analyses reveal fast and continuous network growth as well as clear signs of growing concentration of the network around a few major companies. A key implication is that, at the level of engineering networks, concerns about internet fragmentation might be unfounded and might distract from more salient developments such as organizational concentration
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Search for lepton-flavour-violating decays of Higgs-like bosons.
A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/c2 decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV , collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb-1 . The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limit on the production cross-section multiplied by the branching fraction at 95% confidence level is set and ranges from 22 pb for a boson mass of 45 GeV/c2 to 4 pb for a mass of 195 GeV/c2
Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV
A search for new physics is presented based on an event signature of at least
three jets accompanied by large missing transverse momentum, using a data
sample corresponding to an integrated luminosity of 36 inverse picobarns
collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector
at the LHC. No excess of events is observed above the expected standard model
backgrounds, which are all estimated from the data. Exclusion limits are
presented for the constrained minimal supersymmetric extension of the standard
model. Cross section limits are also presented using simplified models with new
particles decaying to an undetected particle and one or two jets
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
Observation of an Excited Bc+ State
Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+Ï+Ï- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bcâ(2S31)+ state reconstructed without the low-energy photon from the Bcâ(1S31)+âBc+Îł decay following Bcâ(2S31)+âBcâ(1S31)+Ï+Ï-. A second state is seen with a global (local) statistical significance of 2.2Ï (3.2Ï) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date
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