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

Identification of Bare-Airframe Dynamics from Closed-Loop Data Using Multisine Inputs and Frequency Responses

Amethod is presented for computing multiple-input multiple-output frequency responses of bare-airframe dynamics for systems excited using orthogonal phase-optimized multisines and including correlated data arising from control mixing or feedback control. The estimation was posed as the solution to an underdetermined system of linear equations, for which additional information was supplied using interpolation of the frequency responses. A simulation model of the NASA T-2 aircraft having two inputs and two outputs was used to investigate the method in the open-loop configuration and under closed-loop control. The method was also applied to flight test data from the X-56A aeroelastic demonstrator having five inputs and ten outputs and flying under closed-loop control with additional control allocation mixing. Results demonstrated that the proposed method accurately estimates the bare airframe frequency responses in the presence of correlated data from control mixing and feedback control. Results also agreed with estimates obtained using different methods that are less sensitive to correlated inputs

Late Triassic to Jurassic Magmatic and Tectonic Evolution of the Intermontane Terranes in Yukon, Northern Canadian Cordillera: Transition From Arc to Syn-Collisional Magmatism and Post-Collisional Lithospheric Delamination

End-on arc collision and onset of the northern Cordilleran orogen is recorded in Late Triassic to Jurassic plutons in the Intermontane terranes of Yukon, and in development of the synorogenic Whitehorse trough (WT). A synthesis of the extensive data set for these plutons supports interpretation of the magmatic and tectonic evolution of the northern Intermontane terranes. Late Triassic juvenile plutons that locally intrude the Yukon-Tanana terrane represent the northern extension of arc magmatism within Stikinia. Early Jurassic plutons that intrude Stikinia and Yukon-Tanana terranes were emplaced during crustal thickening (200–195 Ma) and subsequent exhumation (190–178 Ma). The syn-collisional magmatism migrated to the south and shows increasing crustal contributions with time. This style of magmatism in Yukon contrasts with coeval, juvenile arc magmatism in British Columbia (Hazelton Group), that records southward arc migration in the Early Jurassic. Exhumation and subsidence of the WT in the north were probably linked to the retreating Hazelton arc by a sinistral transform. East of WT, Early Jurassic plutons intruded into Yukon-Tanana record continued arc magmatism in Quesnellia. Middle Jurassic plutons were intruded after final enclosure of the Cache Creek terrane and imbrication of the Intermontane terranes. The post-collisional plutons have juvenile isotopic compositions that, together with stratigraphic evidence of surface uplift, are interpreted to record asthenospheric upwelling and lithospheric delamination. A revised tectonic model proposes that entrapment of the Cache Creek terrane was the result of Hazelton slab rollback and development of a sinistral transform fault system linked to the collision zone to the north

Flight and analytical investigations of a structural mode excitation system on the YF-12A airplane

A structural excitation system, using an oscillating canard vane to generate force, was mounted on the forebody of the YF-12A airplane. The canard vane was used to excite the airframe structural modes during flight in the subsonic, transonic, and supersonic regimes. Structural modal responses generated by the canard vane forces were measured at the flight test conditions by airframe-mounted accelerometers. Correlations of analytical and experimental aeroelastic results were made. Doublet lattice, steady state double lattice with uniform lag, Mach box, and piston theory all produced acceptable analytical aerodynamic results within the restrictions that apply to each. In general, the aerodynamic theory methods, carefully applied, were found to predict the dynamic behavior of the YF-12A aircraft adequately

Growing Things Rare, Foreign, and Tender : The Early Nineteenth-Century Greenhouse at Gore Place, Waltham Massachusetts

Excavations and ground penetrating radar at Gore Place in Waltham, Massachusetts, uncovered part of an early 19th-century greenhouse (ca. 1806 to the early 1840s) constructed by Christopher and Rebecca Gore. Documentary, archaeological, and geophysical data suggest that the greenhouse was a formal space intended to display exotic plants and that it was built in the relatively new lean-to style, with a tall back wall and a short front wall. The artifact assemblage included tools and small finds related to the greenhouse operation, as well as the remains of at least 149 planting pots. The greenhouse was constructed during a period of intense interest in agricultural experimentation by members of the Massachusetts commercial and political elite, including Gore. Scholars have argued that these men used the positive associations of agriculture to offset some of the contemporary negative connotations of commerce. This article examines the greenhouse in the light of this scientific agricultural movement but also argues that the greenhouse was an extension of the social space of the house and posits that Rebecca Gore may have played a significant role in managing it