The Experts below are selected from a list of 43383 Experts worldwide ranked by ideXlab platform

D. Howe - One of the best experts on this subject based on the ideXlab platform.

Ray C Chang - One of the best experts on this subject based on the ideXlab platform.

  • post flight analysis based on qar in foqa program for jet transport Aircraft Part i angular position monitoring of flight control surface
    Journal of aeronautics astronautics and aviation Series A, 2012
    Co-Authors: Ray C Chang
    Abstract:

    The objective of this paper is to present an evaluating method for irregular deviations of flight control surface deflected angles based on flight data through the post flight analysis. The flight datasets are extracted from quick access recorder (QAR) available in the Flight Operations Quality Assurance (FOQA) program. The lift-to-drag (L/D) model for an aging twin-jet transport will be established through the fuzzy-logic modeling (FLM). The irregular deviations of flight control surfaces can be examined by the L/D model-predicted results through sensitivity analysis. If the irregular deviations of flight control surfaces are not rigged before the flight, the flight control system may not work properly and it may have flight safety concerns in flight. The present concept is an innovation to improve the flight data analysis to monitor the irregular deviations of flight control surface in the present program of FOQA and to increase operational efficiency for the Aircraft carriers.

  • post flight analysis based on qar in foqa program for jet transport Aircraft Part iii aeroelastic effects under a sudden high load
    Journal of aeronautics astronautics and aviation Series A, 2012
    Co-Authors: Szuying Tan, Ray C Chang
    Abstract:

    The transport Aircraft experience frequently higher loads than what are designed for, in Particular, in unusual flight conditions, such as encountering severe atmospheric turbulence, sudden evasive motion in avoiding air collision, and hard landings. The structural damage, fatigue cracking, or non-typical structural deformation may be caused by these high loads. This paper will present a method based on the concept of aeroelastic effects on stability and control derivatives to indirectly determine the structural integrity of transport Aircraft. Aerodynamic models are established through fuzzy-logic modeling (FLM) of the flight data extracted from quick access recorder (QAR). Stability and control derivatives with static aeroelastic effects are then estimated by using these aerodynamic models. Qualitative evaluation of the aeroelastic effects on the wing and tail is based on the second derivatives of normal force and pitching moment coefficients with the angle of attack and dynamic pressure, respectively. A twin-jet transport Aircraft encountered severe atmospheric turbulence with a sudden plunging motion in revenue flight as the study case. The comparative analysis of aeroelastic effects for this twin-jet transport before and during severe atmospheric turbulence will be illustrated in this paper.

Hoon Huh - One of the best experts on this subject based on the ideXlab platform.

  • simulation of superplastic forming diffusion bonding with finite element analysis using the convective coordinate system
    Journal of Materials Processing Technology, 1999
    Co-Authors: K S Lee, Hoon Huh
    Abstract:

    Abstract Superplastic-forming processes are simulated with finite-element analysis in the convective coordinate system. The finite-element code developed is applied to blow-forming processes for demonstration of its validity by predicting the optimum forming pressure cycle. The numerical results provide the pole height and intermediate deformed shapes with variation of the forming time, as well as thickness distribution. The results are compared with those from the experiment and finite-element analysis with a continuum element. The finite-element code is applied to the analysis of a superplastic-forming/diffusion-bonding (SPF/DB) process of four-sheet sandwich Parts. The result shows that the deformed shape with the three-dimensional analysis is different from that with the two-dimensional plane strain because of the end effect, and so is the thickness distribution. The analysis enables accurate prediction of thickness distribution, which is necessary for the good design of multi-sheet sandwich Parts such as an Aircraft Part.

Barater D. - One of the best experts on this subject based on the ideXlab platform.

  • Partial Discharges in Electrical Machines for the More Electrical Aircraft. Part III: Preventing Partial Discharges
    'Institute of Electrical and Electronics Engineers (IEEE)', 2021
    Co-Authors: Rumi A., Lusuardi L., Cavallini A., Pastura M., Barater D., Nuzzo S.
    Abstract:

    In this paper, the results obtained from lab tests on twisted pairs subjected to different voltage waveforms and atmospheric conditions are used to propose how to modify the IEC Std. 60034-18-41. The goal is to make the standard suitable for the More Electrical Aircraft (MEA). The results show that it is initially necessary to screen out materials through simple tests. The enhancement factors for temperature can be modified to consider reduced pressures and temperatures using a simple model. The aging enhancement factor can be reduced considering the reduced sensitivity of the Partial discharge inception voltage (PDIV) at low pressures on the enamel thickness. Eventually, reference will be made to the drive discussed in Part I of this series to draw conclusions about the likelihood of Partial discharge inception in a random wound stator and how to reduce it by modifying either the inverter or the stator insulation. Reference to a random wound motor is made throughout the paper

  • Partial Discharges in Electrical Machines for the More Electric Aircraft. Part I: A Comprehensive Modelling Tool for the Characterization of Electric Drives based on fast switching semiconductors
    'Institute of Electrical and Electronics Engineers (IEEE)', 2021
    Co-Authors: Pastura M., Rumi A., Cavallini A., Nuzzo S., Immovilli F., Toscani A., Franceschini G., Barater D.
    Abstract:

    The arrival on the market of new power devices based on wide bandgap semiconductors has raised a relevant interest due to their superior properties compared to conventional technologies. On the other hand, these devices are inherently characterized by high rates of voltage changes over time, which may result in reliability challenges in electric drives adopting them. In fact, dangerous voltage overshoots at the motor terminals and uneven voltage distributions within the machine windings may occur. These phenomena can trigger a high insulation stress and Partial discharges and, as a consequence, they may concur to the premature failure of the dielectric materials. This paper proposes a flexible and comprehensive modelling approach for the accurate analysis and estimation of both voltage overshoots and voltage distributions in a typical converter-cable-motor system intended for more electric Aircraft applications. The modelling results are validated against experimental measurements carried out on a physical prototype comprising a wide bandgap-based converter, a connecting cable and an electrical machine stator. The findings are then used in the companion papers (Part II and Part III) to investigate the dependence of Partial discharge phenomena on these voltage waveforms, highlight reliability challenges in modern \ub1270 V DC bus voltage drives for the more electric Aircraft and discuss solutions

Marchello, Joseph M. - One of the best experts on this subject based on the ideXlab platform.

  • Polymer Infiltration Studies
    1993
    Co-Authors: Marchello, Joseph M.
    Abstract:

    Significant progress has been made on the preparation of carbon fiber composites using advanced polymer resins during the past three months. Current and ongoing research activities reported herein include: (1) Prepregger Hot Sled Operation; (2) Ribbonizing Powder-Impregnated Towpreg; (3) Textile Composites from Powder-Coated Towpreg: Role of Bulk Factor; and (4) Powder Curtain Prepreg Process. During the coming months research will be directed toward further development of the new powder curtain prepregging method and on ways to customize dry powder towpreg for textile and robotic applications in Aircraft Part fabrication. Studies of multi-tow powder prepregging and ribbon preparation will be conducted in conjunction with continued development of prepegging technology and the various aspects of composite Part fabrication using customized towpreg. Also, work will continue on the analysis of the new solution prepegger

  • Polymer infiltration studies
    1993
    Co-Authors: Marchello, Joseph M.
    Abstract:

    During the past three months, significant progress has been made on the preparation of carbon fiber composites using advanced polymer resins. The results are set forth in recent reports and publications, and will be presented at forthcoming national and international meetings. Current and ongoing research activities reported herein include: textile composites from powder-coated towpreg; role of surface coating in braiding; prepregger hot sled operation; ribbonizing powder-impregenated towpreg; textile composites from powder-coated towpreg; role of bulk factor powder curtain prepreg process advanced tow placement (ATP) open-section Part warpage control. During the coming months research will be directed toward further development of the new powder curtain prepregging method and on ways to customize dry powder towpreg for textile and robotic applications in Aircraft Part fabrication. Studies of multi-tow powder prepregging and ribbon preparation will be conducted in conjunction with continued development of prepregging technology and the various aspects of composite Part fabrication using customized towpreg. Also, during the period ahead work will continue on the analysis of the performance of the new solution prepregger