Electrostatics of crossed arrays of strips [Correspondence]

2010 ◽  
Vol 57 (7) ◽  
pp. 1701-1705 ◽  
Author(s):  
Eugene Danicki
Keyword(s):  
Crossed Arrays

An Adaptive One-Factor-at-a-Time Method for Robust Parameter Design: Comparison With Crossed Arrays via Case Studies

2007 ◽  
Vol 130 (2) ◽  
Author(s):  
Daniel D. Frey ◽  
Nandan Sudarsanam
Keyword(s):  
Case Studies ◽  
Experimental Error ◽  
Fractional Factorial ◽  
Parameter Design ◽  
Robust Parameter Design ◽  
Control Factors ◽  
Starting Point ◽  
Robust Parameter ◽  
Crossed Arrays ◽  
Noise Factors

This paper presents a conceptually simple and resource efficient method for robust parameter design. The proposed method varies control factors according to an adaptive one-factor-at-a-time plan while varying noise factors using a two-level resolution III fractional factorial array. This method is compared with crossed arrays by analyzing a set of four case studies to which both approaches were applied. The proposed method improves system robustness effectively, attaining more than 80% of the potential improvement on average if experimental error is low. This figure improves to about 90% if prior knowledge of the system is used to define a promising starting point for the search. The results vary across the case studies, but, in general, both the average amount of improvement and the consistency of the results are better than those provided by crossed arrays if experimental error is low or if the system contains some large interactions involving two or more control factors. This is true despite the fact that the proposed method generally uses fewer experiments than crossed arrays. The case studies reveal that the proposed method provides these benefits by exploiting, with high probability, both control by noise interactions and also higher order effects involving two control factors and a noise factor. The overall conclusion is that adaptive one-factor-at-a-time, used in concert with factorial outer arrays, is demonstrated to be an effective approach to robust parameter design providing significant practical advantages as compared to commonly used alternatives.

Efficient Operator Marching Method for Analyzing Crossed Arrays of Cylinders

2015 ◽  
Vol 18 (5) ◽  
pp. 1461-1481
Author(s):  
Yu Mao Wu ◽  
Ya Yan Lu
Keyword(s):  
Electromagnetic Field ◽  
Efficient Method ◽  
Periodic Structures ◽  
Three Dimensional ◽  
Circular Cylinders ◽  
Geometric Features ◽  
Spatial Direction ◽  
Number Of Layers ◽  
Crossed Arrays ◽  
Marching Method

AbstractPeriodic structures involving crossed arrays of cylinders appear as special three-dimensional photonic crystals and cross-stacked gratings. Such a structure consists of a number of layers where each layer is periodic in one spatial direction and invariant in another direction. They are relatively simple to fabricate and have found valuable applications. For analyzing scattering properties of such structures, general computational electromagnetics methods can certainly be used, but special methods that take advantage of the geometric features are often much more efficient. In this paper, an efficient method based on operators mapping electromagnetic field components between two spatial directions is developed to analyze structures with crossed arrays of circular cylinders. The method is much simpler than an earlier method based on similar ideas, and it does not require evaluating slowly converging lattice sums.

Turbulent Heat Transfer and Friction in a Square Channel With Discrete Rib Turbulators

1991 ◽  
Vol 113 (3) ◽  
pp. 360-366 ◽  
Author(s):  
S. C. Lau ◽  
R. D. McMillin ◽  
J. C. Han
Keyword(s):  
Heat Transfer ◽  
Stanton Number ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Fully Developed Flow ◽  
Square Channel ◽  
Rib Turbulators ◽  
Discrete Ribs ◽  
Crossed Arrays ◽  
Parallel Arrays

Experiments study the turbulent heat transfer and friction for fully developed flow of air in a square channel with discrete rib turbulators. The discrete ribs are staggered on two opposite walls of the channel in alternate rows of three and two ribs. Nine rib configurations are examined: transverse ribs with an angle of attack (α) of 90 deg, discrete ribs with α = 90 deg, parallel arrays of discrete ribs with α = 45 deg and −45 deg on alternate rows, and parallel and crossed arrays of discrete ribs with α = 60, 45, and 30 deg. The rib height-to-hydraulic diameter ratio and the rib pitch-to-height ratio are 0.0625 and 10, respectively. The Reynolds number ranges from 10,000 to 80,000. Results show that the average Stanton number in the 90 deg discrete rib case is about 10 to 15 percent higher than that in the 90 deg transverse rib case. Turning the discrete ribs on the oppsite walls 60, 45, or 30 deg in the same direction with respect to the main flow increases the average Stanton number 10 to 20 percent over that in the 90 deg discrete rib case. Parallel oblique discrete ribs with α = 60, 45, and 30 deg have comparable performances and have higher overall heat transfer per unit pumping power than 90 deg discrete ribs. Crossed oblique discrete ribs perform poorly compared with 90 deg discrete ribs and are not recommended.

Heat Transfer Characteristics of Turbulent Flow in a Square Channel With Angled Discrete Ribs

1991 ◽  
Vol 113 (3) ◽  
pp. 367-374 ◽  
Author(s):  
S. C. Lau ◽  
R. D. McMillin ◽  
J. C. Han
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Internal Cooling ◽  
Wall Heat Transfer ◽  
Pressure Drops ◽  
Square Channel ◽  
Discrete Ribs ◽  
Crossed Arrays

Experiments have been conducted to study the turbulent heat transfer and friction for fully developed flow of air in a square channel in which two opposite walls are roughened with 90 deg full ribs, parallel and crossed full ribs with angles of attack (α) of 60 and 45 deg, 90 deg discrete ribs, and parallel and crossed discrete ribs with α = 60, 45, and 30 deg. The discrete ribs are staggered in alternate rows of three and two ribs. Results are obtained for a rib height-to-channel hydraulic diameter ratio of 0.0625, a rib pitch-to-height ratio of 10, and Reynolds numbers between 10,000 and 80,000. Parallel angled discrete ribs are superior to 90 deg discrete ribs and parallel angled full ribs, and are recommended for internal cooling passages in gas turbine airfoils. For α = 60 and 45 deg, parallel discrete ribs have higher ribbed wall heat transfer, lower smooth wall heat transfer, and lower channel pressure drop than parallel full ribs. Parallel 60 deg discrete ribs have the highest ribbed wall heat transfer and parallel 30 deg discrete ribs cause the lowest pressure drop. The heat transfer and pressure drops in crossed angled full and discrete rib cases are all lower than those in the corresponding 90 deg and parallel angled rib cases. Crossed arrays of angled ribs have poor thermal performance and are not recommended.

Sign in / Sign up

Export Citation Format

Share Document