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

Simulation of electron transport in quantum well devices

Double barrier resonant tunneling diodes (DBRTD) have received much attention as possible terahertz devices. Despite impressive experimental results, the specifics of the device physics (i.e., how the electrons propagate through the structure) are only qualitatively understood. Therefore, better transport models are warranted if this technology is to mature. In this paper, the Lattice Wigner function is used to explain the important transport issues associated with DBRTD device behavior

The dynamics and control of large flexible space structures-IV

The effects of solar radiation pressure as the main environmental disturbance torque were incorporated into the model of the rigid orbiting shallow shell and computer simulation results indicate that within the linear range the rigid modal amplitudes are excited in proportion to the area to mass ratio. The effect of higher order terms in the gravity-gradient torque expressions previously neglected was evaluated and found to be negligible for the size structures under consideration. A graph theory approach was employed for calculating the eigenvalues of a large flexible system by reducing the system (stiffness) matrix to lower ordered submatrices. The related reachability matrix and term rank concepts are used to verify controllability and can be more effective than the alternate numerical rank tests. Control laws were developed for the shape and orientation control of the orbiting flexible shallow shell and numerical results presented

Meissner screening mass in two-flavor quark matter at nonzero temperature

We calculate the Meissner screening mass of gluons 4--7 in two-flavor quark matter at nonzero temperature. To this end, we study the effective potential of the 2SC/g2SC phases including a vector condensate $$and calculate the Meissner mass from the potential curvature with respect to$$. We find that the Meissner mass becomes real at the critical temperature which is about the half of the chemical potential mismatch. The phase diagram of the neutral two-flavor color superconductor is presented in the plane of temperature and coupling strength. We indicate the unstable region for gluons 4--7 on the phase diagram.Comment: 4 pages, 3 figures, minor revisions to text, version to appear in PR

Rock Magnetic properties of Proterozoic mafic dykes from the Southern margin of Cuddapah Basin

Seventeen basic dykes of Proterozoic age intruding the Archaean basement from the Southern margin of the Cuddapah Basin were studied from five sites for their magnetic characters. NRM intensity (Jn) of the dykes range between 1793 and 57×10−3 Am−1 while magnetic susceptibility (χ) ranges from 31 to 303×10−6 CGS units. Koenigsberger's ratio (Qn) varies from 1 to 55 for most of the specimens. All the above parameters are indicative of retaining the original magnetization in most of the dykes sampled. Based on the above mentioned rock magnetic properties along with hysterisis studies and low temperature (−196°C) magnetic studies, it is inferred that the main magnetic carrier in these dykes is magnetite in multi domain and mixed domain states. Dykes from Tirupati area seems to be magnetically altered

Discosiella Sydow and Discosiellina gen. nov.

Discosiella cylindrospora H. and P. Sydow, the type species of the genus Discosiella H. and P. Sydow, is redescribed from a study of type material. It is concluded that the conidial appendages of this fungus are mucoid in nature, a fact not mentioned by the Sydows in their diagnosis and description. The diagnosis of Discosiella is suitably emended. From the original description of D. longiciliata Agnihothrudu, supplemented by a study of the type material of this species, it is concluded that it cannot be retained in the genus Discosiella as emended in this paper and is now accommodated in a new genus Discosiellina as D. longiciliata (Agnihothrudu) comb. nov