Investigations on Transient and Steady-State Performance of a Micro Heat Pipe

2000 ◽  
Vol 14 (2) ◽  
pp. 161-169 ◽  
Author(s):  
C. B. Sobhan ◽  
Huang Xiaoyang ◽  
Liu Chang Yu
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Micro Heat Pipe ◽  
Transient And Steady State ◽  
Steady State Performance

Quasi-steady-state performance of a heat pipe subjected to transient acceleration loadings

10.2514/3.895 ◽  
1997 ◽  
Vol 11 ◽  
pp. 306-309 ◽  
Author(s):  
Edwin H. Olmstead ◽  
Edward S. Taylor ◽  
Meng Wang ◽  
Parviz Moin ◽  
Scott K. Thomas ◽  
...  
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Quasi Steady State ◽  
Steady State Performance

Steady-State Investigation of Vapor Deposited Micro Heat Pipe Arrays

1995 ◽  
Vol 117 (1) ◽  
pp. 75-81 ◽  
Author(s):  
A. K. Mallik ◽  
G. P. Peterson
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Surface Temperature ◽  
Heat Pipe ◽  
Effective Thermal Conductivity ◽  
Heat Pipes ◽  
Temperature Gradients ◽  
Bottom Surface ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

An experimental investigation of vapor deposited micro heat pipe arrays was conducted using arrays of 34 and 66 micro heat pipes occupying 0.75 and 1.45 percent of the cross-sectional area, respectively. The performance of wafers containing the arrays was compared with that of a plain silicon wafer. All of the wafers had 8 × 8 mm thermofoil heaters located on the bottom surface to simulate the active devices in an actual application. The temperature distributions across the wafers were obtained using a Hughes Probeye TVS Infrared Thermal Imaging System and a standard VHS video recorder. For wafers containing arrays of 34 vapor deposited micro heat pipes, the steady-state experimental data indicated a reduction in the maximum surface temperature and temperature gradients of 24.4 and 27.4 percent, respectively, coupled with an improvement in the effective thermal conductivity of 41.7 percent. For wafers containing arrays of 66 vapor deposited micro heat pipes, the corresponding reductions in the surface temperature and temperature gradients were 29.0 and 41.7 percent, respectively, and the effective thermal conductivity increased 47.1 percent, for input heat fluxes of 4.70 W/cm2. The experimental results were compared with the results of a previously developed numerical model, which was shown to predict the temperature distribution with a high degree of accuracy, for wafers both with and without the heat pipe arrays.

Computing the closed-loop characteristics of a generalized multi-threshold knock controller

2017 ◽  
Vol 19 (9) ◽  
pp. 952-962 ◽  
Author(s):  
Saeed Shayestehmanesh ◽  
James C Peyton Jones ◽  
Jesse Frey
Keyword(s):  
Steady State ◽  
Control Systems ◽  
Closed Loop ◽  
Single Experiment ◽  
Informative Feedback ◽  
Control Laws ◽  
Knock Control ◽  
Transient And Steady State ◽  
Steady State Performance

Most knock controllers respond to knock events which are defined according to some threshold knock intensity. Multi-threshold knock events offer more informative feedback since they encode not just the occurrence of knock events but also some measure of their intensity. While this has the potential for improved control, it is hard to assess the extent to which any benefits are truly realized because (in common with all knock control systems) the results of any single experiment or simulation depends on the random arrival of knock events in that instance. In this article, methods are developed instead to compute the statistical properties of the closed-loop response of a general multi-threshold knock controller, thereby providing a much more complete and rigorous characterization of its performance than has previously been possible. The method is applied to single- and dual-threshold knock controllers and used to provide a rigorous comparison of the transient and steady-state performance of these different control laws. The method can also be used as a calibration aid to assess the effects of different controller gains in reliable, repeatable fashion.

Electrostatic Suspension System for Gyroscopes with Minimum Electrical Disturbing Torque via Non-Linear Pre-Compensation

1996 ◽  
Vol 210 (2) ◽  
pp. 123-127 ◽  
Author(s):  
W Q Yang
Keyword(s):  
Control System ◽  
Steady State ◽  
Position Control ◽  
Complete System ◽  
Suspension System ◽  
System Operation ◽  
Non Linear ◽  
Position Control System ◽  
Transient And Steady State ◽  
Steady State Performance

The new electrostatic suspension system (ESS) presented here is applicable to electrostatically suspended gyroscopes (ESG). The electrical disturbing torque (EDT) acting on the gyro rotor is reduced to much lower levels than possible with the conventional methods, thereby increasing the attainable accuracy of the instrument. This is achieved by eliminating the conventional pre-load voltage and instead applying only control voltages via an analogue non-linear pre-compensator to achieve linear position control system operation despite the square law relating the suspension force to the applied voltage. The transient and steady state performance of the complete system, with changes in position reference and external disturbing forces, are examined with the aid of computer simulations.

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