Direct Force Measurements During Transient Flow about Pitching Flat Plates

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143125/1/6.2017-0995.pd

Unsteady Aerodynamics of Pitching Flat Plate Wings.

In this study, the aerodynamics of a one-degree-of-freedom wing motion, a constant speed pitch ramp, were investigated to determine unsteady flow dynamics and force generation. This kinematics has discernible regions of constant rotation speed and motion acceleration, which helps isolate several effects. This pitching maneuver is analogous to the perching maneuver by birds and insects; a review of aerodynamics of natural flyers is provided. Maneuverability of natural flyers is difficult to emulate in engineered systems; the unsteady flow field of high degree-of-freedom wing kinematics complicates the analysis of the problem and the simpler one-degree-of-freedom kinematics considered here provides valuable insight for man-made fixed wing systems. In this study, dynamic flow field was investigated over thin finite-aspect-ratio-four wings pitching at several constant pitch rates in constant free-stream flows, giving reduced pitch rate in a range of 0 < K < infinity, in an attempt to understand the interplay of time scale between wing motion and free-stream flow. All work was conducted in free-surface water channel in a chord Reynolds number interval of 0 < Re < 13k by means of flow visualization, force measurement, and particle image velocimetry. A simple linear potential flow theory was implemented to elucidate experimental data; effects of reduced pitch rate, pivot axis location, and wing planform were included in the theory. Moreover, the identification of vortical flow structure was presented in correlation with force generation. The rapid increase of aerodynamic forces is associated with the formation of starting vortex in the wake and reduced-pitch-rate effect at the onset of the wing rotation; the gentle increase of aerodynamic forces is relevant to the simultaneous occurrence of leading-edge vortex formation and trailing-edge vortex shedding during constant rotation rate. Low taper-ratio wing enhances force generation at high reduced pitch rate. The pivot-axis location determines the location of the starting vortex. The leading-edge vortex evolution after the end of the motion is delayed; the time delay is the convection time from the leading edge to the pivot-axis location. Linear potential flow theory with rotation-rate effects gives reasonable estimation of force coefficients.PhDAerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/108764/1/htyu_1.pd

Experimental investigation and numerical prediction of the performance of a cross-flow fan

The concept of a fan-wing aircraft configuration for the purpose of vertical takeoff and landing has drawn much attention. Recently, more investigations revealed that a cross-flow fan (CFF) was capable of providing the propulsion. Several characteristics of the off-design performance of a CFF were experimentally measured, but insufficient numerical predictions were obtained. In the present study, the commercial CFD software ANSYS CFX was employed to calculate the unsteady flow through a CFF with a sliding mesh incorporated. The results of the CFD showed the necessity to re-investigate the cross-flow fan with 12-inch diameter, 1/5-inch span and 30 blades, and additional measurement locations were implemented to carry out a more accurate experiment. A new digital sensor array was used to record the pressures within the experiment, which contributed to the high fidelity of the present data. Successful comparisons wre made between the predicted and measured performance at various rotational speeds from an open throttle position to a setting at stall. Visualization of the computed flow field showed where stall occurred, both within the rotor and in the exhaust duct.http://archive.org/details/experimentalinve109452408Approved for public release; distribution is unlimited.Approved for public release; distribution is unlimited

Voice Conversion Based on Cross-Domain Features Using Variational Auto Encoders

An effective approach to non-parallel voice conversion (VC) is to utilize deep neural networks (DNNs), specifically variational auto encoders (VAEs), to model the latent structure of speech in an unsupervised manner. A previous study has confirmed the ef- fectiveness of VAE using the STRAIGHT spectra for VC. How- ever, VAE using other types of spectral features such as mel- cepstral coefficients (MCCs), which are related to human per- ception and have been widely used in VC, have not been prop- erly investigated. Instead of using one specific type of spectral feature, it is expected that VAE may benefit from using multi- ple types of spectral features simultaneously, thereby improving the capability of VAE for VC. To this end, we propose a novel VAE framework (called cross-domain VAE, CDVAE) for VC. Specifically, the proposed framework utilizes both STRAIGHT spectra and MCCs by explicitly regularizing multiple objectives in order to constrain the behavior of the learned encoder and de- coder. Experimental results demonstrate that the proposed CD- VAE framework outperforms the conventional VAE framework in terms of subjective tests.Comment: Accepted to ISCSLP 201

Experimental Investigation of Pitch Ramp-Hold-Return Motion of Flat Plates at Low Reynolds Number

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97118/1/AIAA2012-51.pd

Effects of Planform Geometry and Pivot Axis Location on the Aerodynamics of Pitching Low Aspect Ratio Wings

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106469/1/AIAA2013-2992.pd

Effects of Pivot Location and Reduced Pitch Rate on Pitching Rectangular Flat Plates

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143119/1/1.J055244.pd

Novel inhibitors of the calcineurin/NFATc hub - alternatives to CsA and FK506?

The drugs cyclosporine A (CsA) and tacrolimus (FK506) revolutionized organ transplantation. Both compounds are still widely used in the clinic as well as for basic research, even though they have dramatic side effects and modulate other pathways than calcineurin-NFATc, too. To answer the major open question - whether the adverse side effects are secondary to the actions of the drugs on the calcineurin-NFATc pathway - alternative inhibitors were developed. Ideal inhibitors should discriminate between the inhibition of (i) calcineurin and peptidyl-prolyl cis-trans isomerases (PPIases; the matchmaker proteins of CsA and FK506), (ii) calcineurin and the other Ser/Thr protein phosphatases, and (iii) NFATc and other transcription factors. In this review we summarize the current knowledge about novel inhibitors, synthesized or identified in the last decades, and focus on their mode of action, specificity, and biological effects