Generalized Force Directed Relaxation with Optimal Regions and Its Applications to Circuit Placement

2017 ◽  
Author(s):  
Yao Wen Chang
Keyword(s):  
Generalized Force ◽  
Circuit Placement

Physical Properties of Transfer Function Zeros for Collocated Control in Flexible Structure System

1995 ◽  
Author(s):  
Chingyei Chung ◽  
Chin-yuh Lin
Keyword(s):  
Transfer Function ◽  
Circulatory System ◽  
Flexible Structure ◽  
Structure System ◽  
Zero Dynamic ◽  
Damping Matrix ◽  
Generalized Force ◽  
Function Zeros ◽  
Gyroscopic Systems ◽  
Collocated Control

Abstract In this paper, the physical meaning of transfer function zeros for collocated control in a general flexible structure system is discussed. For a flexible structure system, we propose the “Zero Dynamic Theorem”. The theorem states that in a flexible structure system, the flexible structure can be a circulatory system (non-sysmetric stiffness matrix) with viscous and gyroscopic damping (non-symmetric damping matrix), if the sensor output (generalized displacement) and the actuator input (generalized force) are “dual type” and the transfer function is strict proper and coprime (no pole/zero cancellation); then, the transfer function zeros are the natural frequencies of constrained structure. Furthermore, with this theorem, the interlacing pole/zero property for the gyroscopic systems is presented.

Effect of Scaling of Blade Row Sectors on the Prediction of Aerodynamic Forcing in a Highly-Loaded Transonic Compressor Stage

2009 ◽  
Author(s):  
Mari´a A. Mayorca ◽  
Jesu´s A. De Andrade ◽  
Damian M. Vogt ◽  
Hans Ma˚rtensson ◽  
Torsten H. Fransson
Keyword(s):  
Second Harmonic ◽  
Harmonic Excitation ◽  
Navier Stokes ◽  
Test Case ◽  
Moderate Amount ◽  
Object A ◽  
Transonic Compressor ◽  
Geometrical Scaling ◽  
Direct Indication ◽  
Generalized Force

An investigation of the sensitivity of a geometrical scaling technique on the blade forcing prediction and mode excitability has been performed. A stage of a transonic compressor is employed as test object. A scaling ratio is defined which indicates the amount of scaling from the original geometry. Different scaling ratios are selected and 3D Navier Stokes unsteady calculations completed for each scaled configuration. A full annulus calculation (non-scaled) is performed serving as reference. The quantity of interest is the generalized force, which gives a direct indication of the mode excitability. In order to capture both up- and downstream excitation effects the mode excitability has been assessed on both rotor and stator blades. The results show that first harmonic excitation can be predicted well for both up- and downstream excitation using moderate amount of scaling. On the other hand, the predictions of second harmonic quantities do show a higher sensitivity to scaling for the investigated test case.

Large-Scale Circuit Placement

2007 ◽  
pp. 121-146
Author(s):  
Ameya R. Agnihotri ◽  
Satoshi Ono ◽  
Mehmet Can Yildiz ◽  
Patrick H. Madden
Keyword(s):  
Large Scale ◽  
Circuit Placement

Circuit Placement

2008 ◽  
pp. 143-146
Author(s):  
Andrew A. Kennings ◽  
Igor L. Markov
Keyword(s):  
Circuit Placement

Influence of Detailing on Aerodynamic Forcing of a Transonic Axial Turbine Stage and Forced-Response Prediction for Low-Engine-Order (LEO) Excitation

2017 ◽  
Author(s):  
Tobias R. Müller ◽  
Damian M. Vogt ◽  
Klemens Vogel ◽  
Bent A. Phillipsen ◽  
Peter Hönisch
Keyword(s):  
Numerical Study ◽  
Response Prediction ◽  
Forced Response ◽  
Resonance Excitation ◽  
Response Analysis ◽  
Turbine Stage ◽  
Flow Induced Vibration ◽  
Axial Turbine ◽  
Timing Data ◽  
Generalized Force

The effects of detailing on the prediction of forced-response in a transonic axial turbine stage, featuring a parted stator design, asymmetric inlet and outlet casings as well as rotor cavities, is investigated. Ensuring the mechanical integrity of components is of paramount importance for the safe and reliable operation of turbomachines. Among others, flow induced resonance excitation can lead to high-cycle fatigue (HCF) and potentially to damage of components unless properly damped. This numerical study is assessing the necessary degree of detailing in terms of spatial and temporal discretization, boundary conditions of the pre-stressed rotor geometry as well as geometrical detailing for the reliable prediction of the aerodynamic excitation of the structure. In this context, the sensitivity of the aerodynamic forcing is analyzed by means of the generalized force criterion, showing a significant influence for some of the investigated variations of the numerical model. Moreover, the origin and further progression of several low-engine-orders (LEO) within the flow field, as well as their interaction with different geometric details has been analyzed based on the numerical results obtained from a full 360° CFD-calculation of the investigated turbine stage. The predicted flow induced vibration of the structure has been validated by means of a full forced-response analysis, where a good agreement with tip-timing data has been found.

Donor–acceptor interactions in Friedel–Crafts systems. The CH3COCl•AlCl3 addition compound

1970 ◽  
Vol 48 (24) ◽  
pp. 3860-3871 ◽  
Author(s):  
D. Cassimatis ◽  
J. P. Bonnin ◽  
T. Theophanides
Keyword(s):  
Active Species ◽  
Addition Compound ◽  
Vibrational Assignments ◽  
Carbonyl Band ◽  
Generalized Force ◽  
Donor Acceptor ◽  
Structure Formula ◽  
Limit Form

The infrared spectra of CH3COCl and CH3COCl•AlCl3 have been studied from 4000 to 300 cm−1 with a Perkin–Elmer 621 grating spectrophotometer. The results indicate that the addition compound CH3COCl•AlCl3 exists under three structures, two ionic and one dative structure. The distinct ionic structures are the carbonium type structure [Formula: see text] with a carbonyl band at 2200 cm−1 (type 1) and a structure visualized as a hybrid between resonating structures[Formula: see text]where the mesomeric limit form corresponding to the hyperconjugation is preponderant, with a carbonyl band at 2300 cm−1 (type 2). Vibrational assignments have been made for the two ions and supported by normal coordinate analysis. Two sets of force constants have been derived on the basis of the generalized force field for the two ionic structures to provide a correspondence between observed and calculated frequencies. Evidence would seem to show that the active species in the Friedel–Crafts ketone synthesis is the oxocarbonium type 1 acetylium ion.

Sign in / Sign up

Export Citation Format

Share Document