Analysis of an unswept propfan blade with a semiempirical dynamic stall model

The time history response of a propfan wind tunnel model with dynamic stall is studied analytically. The response obtained from the analysis is compared with available experimental data. The governing equations of motion are formulated in terms of blade normal modes which are calculated using the COSMIC-NASTRAN computer code. The response analysis considered the blade plunging and pitching motions. The lift, drag and moment coefficients for angles of attack below the static stall angle are obtained from a quasi-steady theory. For angles above static stall angles, a semiempirical dynamic stall model based on a correction to angle of attack is used to obtain lift, drag and moment coefficients. Using these coefficients, the aerodynamic forces are calculated at a selected number of strips, and integrated to obtain the total generalized forces. The combined momentum-blade element theory is used to calculate the induced velocity. The semiempirical stall model predicted a limit cycle oscillation near the setting angle at which large vibratory stresses were observed in an experiment. The predicted mode and frequency of oscillation also agreed with those measured in the experiment near the setting angle

The effects of rotational flow, viscosity, thickness, and shape on transonic flutter dip phenomena

The transonic flutter dip phenomena on thin airfoils, which are employed for propfan blades, is investigated using an integrated Euler/Navier-Stokes code and a two degrees of freedom typical section structural model. As a part of the code validation, the flutter characteristics of the NACA 64A010 airfoil are also investigated. In addition, the effects of artificial dissipation models, rotational flow, initial conditions, mean angle of attack, viscosity, airfoil thickness and shape on flutter are investigated. The results obtained with a Euler code for the NACA 64A010 airfoil are in reasonable agreement with published results obtained by using transonic small disturbance and Euler codes. The two artificial dissipation models, one based on the local pressure gradient scaled by a common factor and the other based on the local pressure gradient scaled by a spectral radius, predicted the same flutter speeds except in the recovery region for the case studied. The effects of rotational flow, initial conditions, mean angle of attack, and viscosity for the Reynold's number studied seem to be negligible or small on the minima of the flutter dip

VAS score assessment for outcome of posterior lumbar inter body fusion in cases of lumbar canal stenosis

Background: One of the major causes for disability in adult working population is degenerative lumbosacral spine disorders are fairly common in middle aged and elderly population. Lumbar canal stenosis remains one of the most frequently encountered clinically important degenerative spinal disorders requiring operative treatment in the aging population. The objective of the present study is to assess the outcome of posterior lumbar inter body fusion in cases of lumbar canal stenosisMethods: The present study, 30 cases of lumbar canal stenosis, who were treated operatively with decompression and posterior lumbar inter body fusion, which was carried out over a period of 6 months in a tertiary care center were included. 16 women and 14 men were included in the study.Results: Most patients were in the age group of 41-50 years (36.7%) followed by 51-60 years (33.3%). In this study it was found that there was significant improvement in VAS score for back pain and leg pain over the 6 month follow-up. There is significant difference between mean improvement in VAS score with respect to number of levels involved for leg pain (p =0.01).  There is no statistical significance difference between number of levels involved and improvement in back pain (p =0.66).Conclusions:VAS score showed posterior lumbar interbody fusion with interbody cage and local graft with posterior instrumentation gave significantly improved clinical and functional outcome by causing significant reduction in pain and patient disability.

Study on correlation between combined femoral and acetabular anteversion in patients undergoing total hip arthroplasty using CT scan

Background: The concept of hip Arthroplasty started as a very simple rudimentary idea of excising the hip joint (excision Arthroplasty), through to fusion of the hip, to actual replacement of the joint surfaces with various artificial substances ranging from glass, plastic, pig's bladder, ivory, ceramic polyethylene (PE) and more recently to actual metal-on metal hip replacement. Hip replacement is usually considered only after other therapies, such as physical therapy and pain medications, have failed. To determine the combined femoral and acetabular anteversion in patients undergoing total hip arthroplasty using CT scan.Methods: Patients admitted in hospital who underwent total hip arthroplasty from July 2013 to July 2015 were included in the study.Results: The study comprised of 40 patients, there were 15 (37.5%) females and 25 (62.5%) males. There were 7(17.5%) patients with less than 30º femoral component anteversion, 26 (65%) patients were in the range of 30º - 50º anteversion and 7 (17.5%) patients were in the range of more than 50º anteversion. There were 10 (25%) patients with less than 40 º combined anteversion, 23 (57.5%) patients were in the range of 40 º - 70 º anteversion and 7 (17.5 %) patients were in the range of more than 70 º anteversion.Conclusions: The functional outcome of the patients was better when the combined anteversion was between 4-7ff as compared to the functional outcome when the combined anteversion was either less than 40 " or more than 70'.  However, we required larger group of study to validate the findings

Towards Benchmarking Scene Background Initialization

Given a set of images of a scene taken at different times, the availability of an initial background model that describes the scene without foreground objects is the prerequisite for a wide range of applications, ranging from video surveillance to computational photography. Even though several methods have been proposed for scene background initialization, the lack of a common groundtruthed dataset and of a common set of metrics makes it difficult to compare their performance. To move first steps towards an easy and fair comparison of these methods, we assembled a dataset of sequences frequently adopted for background initialization, selected or created ground truths for quantitative evaluation through a selected suite of metrics, and compared results obtained by some existing methods, making all the material publicly available.Comment: 6 pages, SBI dataset, SBMI2015 Worksho

Superconductivity in Ru substituted BaFe2-xRuxAs2

The occurrence of bulk superconductivity at ~22 K is reported in polycrystalline samples of BaFe2-xRuxAs2 for nominal Ru content in the range of x=0.75 to 1.125. A systematic suppression of the spin density wave transition temperature (TSDW) precedes the appearance of superconductivity in the system. A phase diagram is proposed based on the measured TSDW and superconducting transition temperature (TC) variations as a function of Ru composition. Band structure calculations, indicate introduction of electron carriers in the system upon Ru substitutiom. The calculated magnetic moment on Fe shows a minimum at x=1.0, suggesting that the suppression of the magnetic moment is associated with the emergence of superconductivity. Results of low temperature and high field Mossbauer measurements are presented. These indicate weakening of magnetic interaction with Ru substitutionComment: 20 pages 10 figure

Some three dimensional elasto-dynamic solutions of layered shells

Three dimensional solutions for natural frequencies and mode shapes of layered composite shells obtained by using the finite layer method, are presented in this paper. Higher order theories for laminated shells are discussed

Some theoretical models for solitary structures of boundary layer waves

International audienceSolitary electrostatic structures have been observed in and around auroral zone field lines at various altitudes ranging from close to the ionosphere, to the magnetopause low-latitude boundary layer (LLBL) and cusp on the dayside, and to the plasma sheet boundary layer on the night-side. In this review, various models based on solitons/double layers and BGK modes or phase space holes are discussed in order to explain the characteristics of these solitary structures