46 research outputs found
Conceptual Design of Aeroelastic Demonstrator for Whirl Flutter Simulation
No full textThis paper deals with the conceptual design of the
new aeroelastic demonstrator for the whirl flutter simulation. The
paper gives a theoretical background of the whirl flutter phenomenon
and describes the events of the whirl flutter occurrence in the
aerospace practice. The second part is focused on the experimental
research of the whirl flutter on aeroelastic similar models. Finally the
concept of the new aeroelastic demonstrator is described. The
demonstrator represents the wing and engine of the twin turboprop
commuter aircraft including a driven propeller. It allows the changes
of the main structural parameters influencing the whirl flutter
stability characteristics. It is intended for the experimental
investigation of the whirl flutter in the wind tunnel. The results will
be utilized for validation of analytical methods and software tools
[Book Review of] \u3cem\u3eMedicine and Religion: Strategies of Care,\u3c/em\u3e edited by Donald W. Shriver, Jr.
No full textDehydration and the Effects on Collegiate Wrestlers
No full textThe purpose of this review of literature is to analyze the research available dealing specifically with dehydration and rehydration issues as they relate to collegiate wrestlers. More specifically this paper will serve a practical purpose in the provision of an examination and identification of specific suggestions regarding the application of the use of fluids in wrestling for promotion of high level performance while maintaining optimal hydration
Active Control of Three-Surface Aeroelastic Model
No full textThe present paper describes research activities related to the Active Aeroelastic Aircraft Structures Project, fulfilled by Politecnico di Milano, dealing with the aeroelastic demonstrator named X-DIA. This aircraft is a onetenth geometrically and dynamically scaled model of a regional transport airplane, and it has been built to become a wind-tunnel benchmark for experimenting with new aeroelastic concepts. All movable foreplane surfaces and wings with distributed multiple control surfaces are here installed to improve overall aeroelastic response and thus to improve airplane stability and even fuselage flight comfort. An identical location of accelerations and forces-based control system has been implemented: numerical and experimental results show a remarkable capability of this
device in damping fuselage bending and torsion modes. The following pages will provide information about the research project, describing methodologies adopted and experiment results taken in wind-tunnel testing
Effects of Ammonia Inhalants in Humans: A Review of the Current Literature Regarding the Benefits, Risks, and Efficacy
No full textAeroelastic analysis of twin turboprop utility aircraft
No full text This article deals with aeroelastic certification analyses of the new-generation Czech twin turboprop utility aircraft. The article is focused on the first phase of analyses before the ground vibration test (GVT) of the prototype. It describes the analytical model as well as the used tools and methods. The description of specific blocks of analyses follows afterwards. It includes the preliminary flutter analyses, static aeroelastic analyses (control reversal and divergence), modal analyses, and large parametric flutter analyses (surface, control surfaces, and tab flutter). The flutter characteristics of the structure with respect to changes of the selected parameters are presented. Furthermore, the preparation of the GVT (i.e. the optimization of the exciter and accelerometer positions based on the analytical results, and the whirl flutter analyses by means of an optimization-based approach to find the critical stability boundaries are explained). Finally, the performed activities are summarized and the next phase of aeroelastic certification (GVT, final analyses, and flight flutter tests) and the aircraft development are outlined. </jats:p
Impact of rest-redistribution on fatigue during maximal eccentric knee extensions
No full textRedistributing long inter-set rest intervals into shorter but more frequent rest intervals generally maintains concentric performance, possibly due to improved energy store maintenance. However, eccentric actions require less energy than concentric actions, meaning that shorter but more frequent sets may not affect eccentric actions to the same degree as concentric actions. Considering the increased popularity of eccentric exercise, the current study evaluated the effects of redistributing long inter-set rest periods into shorter but more frequent rest periods during eccentric only knee extensions. Eleven resistance-trained men performed 40 isokinetic unilateral knee extensions at 60°·s-1 with 285 s of total rest using traditional sets (TS; 4 sets of 10 with 95 s inter-set rest) and rest-redistribution (RR; 20 sets of 2 with 15 s inter-set rest). Before and during exercise, muscle oxygenation was measured via near-infrared spectroscopy, and rating of perceived exertion (RPE) was recorded after every 10th repetition. There were no differences between protocols for peak torque (RR, 241.58±47.20 N; TS, 231.64±48.87 N; p=0.396) or total work (RR, 215.26±41.47 J; TS, 209.71±36.02 J; p=0.601), but moderate to large effect sizes existed in later repetitions (6,8,10) with greater peak torque during RR (d=0.66-1.19). For the entire session, RR had moderate effects on RPE (RR, 5.73±1.42; TS, 6.09±1.30; p=0.307; d=0.53) and large effects on oxygen saturation (RR, 5857.4±310.0; TS, 6495.8±273.8; p=0.002, d=2.13). Therefore, RR may maintain peak torque or total work during eccentric exercise, improve oxygen utilization at the muscle, and reduce the perceived effort
Preliminary interpretation of a marine deep seismic sounding survey in the region of Explorer ridge
No full text A marine seismic system for recording near-vertical incidence to wide-angle reflected waves and refracted waves with penetration from the ocean bottom to the upper mantle (deep seismic sounding or DSS) has been developed. Signals from six individual hydrophones suspended at 45 m depth from a 600 m cable trailed behind the receiving ship are recorded in digital form. Using charges ranging from 2.3 to 280 kg, two reversed DSS profiles were recorded in the region of Explorer ridge during 1974. A preliminary interpretation of the profiles based on first-arrival information in the range 4 to 80 km has been made.The reversed profile run across the ridge showed no anomalous effects as the ridge was crossed; the profile on Juan de Fuca plate, paralleling the ridge, exhibited traveltime branch offsets and delays. These have been interpreted as due to faulting with a vertical component of offset of about 4 km. The reversed upper mantle velocities are 7.85 and'7.30 km/s indirections perpendicular and parallel to the ridge. Anisotropy is proposed to explain these different velocities and gives a 7% anisotropic effect. The data require that 'layer 2' comprise at least two layers with velocities of 4.13 km/s and 5.25 km/s and individual depth extents ranging from 1 to 2 km. Compared with crustal sections from other ridge areas, the interpretation gives a thick 'layer 3' (up to 6 km) near the ridge crest. The sub-bottom thickness of the oceanic crust varies between 7 and 9 km, except in the faulted region, where the 7.30 km/s material is present less than 3 km from the bottom. </jats:p
Traditional sets versus rest-redistribution: a laboratory-controlled study of a specific cluster set configuration at fast and slow velocities
No full textThis study investigated redistributing long inter-set rest intervals into shorter but more frequent intervals at 2 different concentric velocities. Resistance-trained men performed 4 randomised isokinetic unilateral knee extension protocols, 2 at 60°·s−1 and 2 at 360°·s−1. At each speed, subjects performed 40 repetitions with 285 s of rest using traditional sets (TS; 4 sets of 10 with 95 s of inter-set rest) and rest-redistribution (RR; 20 sets of 2 with 15 s inter-set rest). Before and at 2, 5, and 10 min after exercise, tensiomyography (TMG) and oxygenation (near-infrared spectroscopy; NIRS) were measured. NIRS was also measured during exercise, and rating of perceived exertion (RPE) was recorded after every 10 repetitions. At both speeds, RR displayed greater peak torque, total work, and power output during latter repetitions, but there were no differences between TS or RR when averaging all 40 repetitions. The RPE was less during RR at both speeds (p < 0.05). RR increased select muscle oxygen saturation and blood flow at both speeds. There were no effects of protocol on TMG, but effect sizes favoured a quicker recovery after RR. RR was likely beneficial in maintaining performance compared with the latter parts of TS sets and limiting perceived and peripheral fatigue.
Novelty
Although effective at slow velocities, rest-redistribution was likely more effective during high-velocity movements in this study.
Rest-redistribution maintained the ability to produce force throughout an entire range of motion.
Rest-redistribution reduced RPE during both high-velocity and high-force movements.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
