The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
S Sampath - One of the best experts on this subject based on the ideXlab platform.
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Process maps for plasma spraying of yttria stabilized zirconia an integrated approach to design optimization and reliability
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: A Vaidya, V Srinivasan, T Streibl, M Friis, S SampathAbstract:Abstract Plasma-sprayed yttria-stabilized zirconia (YSZ) continues to play an important role in enhancing performance of both propulsion and land-based gas turbine engines. Tailoring the microstructure and properties of these thermal barrier coatings towards achieving both prime reliance and manufacturing reproducibility is a complex task due to the multitude of interrelated parameters that influence the plasma spray Process and the deposit formation dynamics. In this article, we report on a study that connects thermal spray coatings through Process science and materials science utilizing the concept of Process maps. Process maps are representations of interrelationships among control parameters and measured responses. First-order Process maps have been established for three YSZ powder morphologies, linking the plasma forming torch parameters to the particle state (responses) through a design of experiments approach and in-flight diagnostics. Refinements to representation of the raw particle characteristics are proposed through the use of group parameters (melting index and kinetic energy) from the experimental results. First-order Process maps have been used for Process parameterization and feedback control. Correlating the first-order responses with coating properties allows representation of coating properties in the form of Second-Order Process maps and enables identification of Process windows. As will be demonstrated in this paper, these advances provide a platform with which to construct comprehensive Process-microstructure–property relationships with implications for coating design, Process efficiency and full-field assessment of manufacturing reliability.
J Ullrich - One of the best experts on this subject based on the ideXlab platform.
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role of elastic projectile electron scattering in double ionization of helium by fast proton impact
Physical Review A, 2009Co-Authors: Michael Schulz, M F Ciappina, Tom Kirchner, Daniel Fischer, R Moshammer, J UllrichAbstract:We present a systematic study of atomic four-body fragmentation dynamics. To this end we have measured a variety of multiple differential double ionization cross sections for 6 MeV $p+\text{He}$ collisions. The data are compared to a first-order calculation with correlated electrons and to a simulation representing a Second-Order Process, with some experimental results seemingly in favor of the first, others in agreement with the second approach. This apparent conflict can be resolved by accounting for elastic scattering between the projectile and one electron already promoted to the continuum through electron-electron correlation in the first-order Process.
Galal A. Hassaan - One of the best experts on this subject based on the ideXlab platform.
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TUNING OF A PIDF CONTROLLER USED WITH A HIGHLY OSCILLATING SECOND ORDER Process
2020Co-Authors: Galal A. Hassaan, Mohammed A. Al-gamil, Maha M. LashinAbstract:-High oscillation in industrial Processes is something undesired and controller tuning has to solve this problems. PDF and PIDF are controller modes which are expected to overcome this problem. This research work has proven that the PIDF is the genuine solution for the high level Process oscillation. A second order Process of 85.45 % maximum overshoot and 8 seconds settling time is controlled using a PIDF controller (through simulation). The controller is tuned by minimizing the sum of absolute error of the control system using MATLAB. A functional constrains is imposed on the maximum percentage overshoot. The result was cancelling completely the Process oscillation with a zero overshoot and a 0.62 seconds settling time. The performance of the PIDF controller is compared with the classical PID controller with the same Process. Keywords—PDF controller, PIDF controller, overshoot, maximum overshoot, gain, and settling time.
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Tuning of a PDFF Controller used with a Very Slow Second Order Process
2020Co-Authors: Galal A. HassaanAbstract:Slow response of physical Processes represents a dynamic problem and has to be solved through automatic control engineering by selecting reasonable controllers or compensators. A PDFF controller is proposed in this work to overcome the slow response dynamic problem. The controller is tuned using an IAE objective function and three functional constraints controlling the time-based specifications of the closed-loop control system and maintaining a stable linear control system during the optimization Process. A second order Process of 164.5 seconds settling time is controlled using a PDFF controller (through simulation). The controller is tuned by minimizing the sum of absolute error of the control system using MATLAB. Functional constraints are imposed on the maximum percentage overshoot, settling time and stability condition. The result was reforming the Process slow response and producing a closed-loop control systems of a maximum percentage overshoot of 0.72 % and a settling time of 0.77 seconds. The performance of the tuned-PDFF controlled Process is compared with that tuned using the ITAE standard forms and with control using a PID-controller.
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Tuning of a Feedforward Lag-Lead Second-Order Compensator used with a Highly Oscillating Second-Order Process
viXra, 2016Co-Authors: Galal A. HassaanAbstract:Lag-lead compensators are well known in automatic control engineering. They have 4 parameters to be adjusted (tuned) for proper operation. The frequency response of the control system or the root locus plot are traditionally used to tune the compensator in a lengthy procedure. A highly oscillating Second-Order Process has a time response to a unit step input of 85.4 % maximum overshoot and about 6 seconds settling time is controlled using a lag-lead compensator (through simulation). The lag-lead compensator is tuned by minimizing the sum of time multiplied by the absolute error (ITAE) of the control system using MATLAB. Three functional constrains are used to control the performance of the lag-lead compensated control system. The result was reducing the Process oscillation to 6.926 % overshoot and a 1.413 seconds settling time. The steady-state characteristics of closed-loop control system using the lag-lead compensator were excellent. It is possible reduce the steady-state error to any desired value through one of the compensator parameters.
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TUNING OF A FIRST-ORDER LAG-LEAD COMPENSATOR USED WITH A VERY SLOW Second-Order Process
International Journal of Advances in Engineering & Technology, 2015Co-Authors: Galal A. HassaanAbstract:Lag-lead compensators are well known in automatic control engineering. They have 3 or 4 parameters to be adjusted (tuned) for proper operation depending on the compensator order. The frequency response of the control system or the root locus plot are traditionally used to tune the compensator in a lengthy procedure. A selected very slow Second-Order Process has a time response to a unit step input of 150 seconds settling time is controlled using a first-order lag-lead compensator (through simulation). The lag-lead compensator is tuned by minimizing the sum of square of errors of the control system using MATLAB. Four functional constrains are used to control the performance of the lag-lead compensated control system. The result was reducing the settling time to only 0.666 seconds. The steady-state characteristics of closed-loop control system using the first-order lag-lead compensator were excellent. It was possible reduce the steady-state error to less than 0.01 using the tuned first-order lag-lead compensator.
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Robustness Of I-PD, PD-PI And PI-PD Controllers Used With Second-Order Processes
International Journal of Scientific & Technology Research, 2014Co-Authors: Galal A. HassaanAbstract:Robustness is one of the requirements used in controllers and compensators design. The designs presented in the previous papers did not consider the robustness of the controller or compensator. Therefore, the objective of this paper is to investigate the robustness of I-PD, PD-PI and PI-PD controllers used to control Second-Order Processes against uncertainty in the Process parameters. A variation of ± 20 % in Process parameters is considered through simulation to study its effect on the system performance parameters using the tuned controllers. With I-PD controller controlling an underdamped second order Process, the variation in Process natural frequency and damping ratio has almost no effect on the maximum percentage overshoot , maximum percentage undershoot , settling time and the phase margin of the control system. The variation of the Process natural frequency produced a maximum change of 33 % in the system gain margin. The damping ratio change does not affect the gain margin of the system. With PD-PI controller controlling the underdamped second order Process, the variation in Process natural frequency and damping ratio has almost no effect on the maximum percentage overshoot , maximum percentage undershoot , gain margin and the phase margin of the control system. The variation of the Process natural frequency produced a maximum change of 56.5 % in the system settling time. The damping ratio change does not affect the settling time of the system. With PI-PD controller controlling the underdamped second order Process, the variation in Process natural frequency and damping ratio has almost no effect on the maximum percentage overshoot , maximum percentage undershoot and gain margin of the control system. The variation of the Process natural frequency produced a maximum change of 5.2 % in the system settling time and 3.67 % in the phase margin. The variation of the Process damping ratio produced a maximum change of 0.05 % in the system settling time and has no effect on the system phase margin.
Zeming Qi - One of the best experts on this subject based on the ideXlab platform.
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potential white light long lasting phosphor dy3 doped aluminate
Applied Physics Letters, 2005Co-Authors: Zeming QiAbstract:The white-light long-lasting phosphor CaAl2O4:Dy3+ was prepared and investigated. The white-light afterglow spectra under the irradiation of 254 or 365nm are comprised of the blue light emission and the yellow light emission, originating from the transitions of F9∕24→H15∕26, F9∕24→H13∕26 in the 4f9 configuration of Dy3+. The afterglow can last 32min for the best sample with Dy-doped concentration of 2at.%. The decay curve and the thermoluminescence curve show to be a Second-Order Process. Thermoluminescence curves exhibit a complicated structure in the range of 230–450K with the peaks at 244, 280, 310, and 346K. The two thermoluminescence bands peaking above room temperature have corresponding traps with the depths of 0.54 and 0.61eV, which are responsible for the afterglow emission at room temperature. This work provides a promising approach for the development of white-light long-lasting phosphor.
A Vaidya - One of the best experts on this subject based on the ideXlab platform.
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Process maps for plasma spraying of yttria stabilized zirconia an integrated approach to design optimization and reliability
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: A Vaidya, V Srinivasan, T Streibl, M Friis, S SampathAbstract:Abstract Plasma-sprayed yttria-stabilized zirconia (YSZ) continues to play an important role in enhancing performance of both propulsion and land-based gas turbine engines. Tailoring the microstructure and properties of these thermal barrier coatings towards achieving both prime reliance and manufacturing reproducibility is a complex task due to the multitude of interrelated parameters that influence the plasma spray Process and the deposit formation dynamics. In this article, we report on a study that connects thermal spray coatings through Process science and materials science utilizing the concept of Process maps. Process maps are representations of interrelationships among control parameters and measured responses. First-order Process maps have been established for three YSZ powder morphologies, linking the plasma forming torch parameters to the particle state (responses) through a design of experiments approach and in-flight diagnostics. Refinements to representation of the raw particle characteristics are proposed through the use of group parameters (melting index and kinetic energy) from the experimental results. First-order Process maps have been used for Process parameterization and feedback control. Correlating the first-order responses with coating properties allows representation of coating properties in the form of Second-Order Process maps and enables identification of Process windows. As will be demonstrated in this paper, these advances provide a platform with which to construct comprehensive Process-microstructure–property relationships with implications for coating design, Process efficiency and full-field assessment of manufacturing reliability.
