Band Radiation within Diffuse-Walled Enclosures—Part II: An Approximate Method Applied to Simple Enclosures

1979 ◽  
Vol 101 (1) ◽  
pp. 85-89 ◽  
Author(s):  
D. A. Nelson
Keyword(s):  
Approximate Method ◽  
High Accuracy ◽  
Principal Feature ◽  
Band Absorption ◽  
Emitting Media ◽  
Low Order

An asymptotically exact approximate method of analysis for band radiation has been applied to some simple enclosures. The principal feature of the method is direct utilization of band absorption formulations for absorbing-emitting media. The procedure is shown to be capable of arbitrarily high accuracy and to have very acceptable errors for low order approximations.

Research on Modeling of Propeller in a Turboprop Engine

2015 ◽  
Vol 32 (2) ◽  
Author(s):  
Jiaqin Huang ◽  
Xianghua Huang ◽  
Tianhong Zhang
Keyword(s):  
Approximate Method ◽  
Real Time ◽  
Integrated Control ◽  
Computing Time ◽  
High Accuracy ◽  
Surface Theory ◽  
Model Based ◽  
Lifting Surface ◽  
Strip Theory ◽  
Lift And Drag

AbstractIn the simulation of engine-propeller integrated control system for a turboprop aircraft, a real-time propeller model with high-accuracy is required. A study is conducted to compare the real-time and precision performance of propeller models based on strip theory and lifting surface theory. The emphasis in modeling by strip theory is focused on three points as follows: First, FLUENT is adopted to calculate the lift and drag coefficients of the propeller. Next, a method to calculate the induced velocity which occurs in the ground rig test is presented. Finally, an approximate method is proposed to obtain the downwash angle of the propeller when the conventional algorithm has no solution. An advanced approximation of the velocities induced by helical horseshoe vortices is applied in the model based on lifting surface theory. This approximate method will reduce computing time and remain good accuracy. Comparison between the two modeling techniques shows that the model based on strip theory which owns more advantage on both real-time and high-accuracy can meet the requirement.

Internal Blocking Probability Calculation in Switching Networks with Additional Inter-Stage Links and Mixture of Erlang and Engset Traffic

2012 ◽  
Vol 17 (1-2) ◽  
pp. 67-79 ◽  
Author(s):  
Mariusz Gła̧bowski ◽  
Michał Dominik Stasiak
Keyword(s):  
Approximate Method ◽  
Simulation Study ◽  
Infinite Number ◽  
Blocking Probability ◽  
High Accuracy ◽  
Switching Networks ◽  
Theoretical Assumptions ◽  
Probability Calculation

Abstract In the article a new analytical approximate method for modeling multi-service switching networks with overflow links is proposed. The method can be used for blocking probability calculation in switching networks that are offered multi-service traffic generated by finite and infinite number of sources, i.e., in switching networks with multi-service Engset traffic, in switching networks with multiservice Erlang traffic, as well as in multi-service switching networks with Erlang and Engset traffic. The simulation study performed proves high accuracy of the method proposed and confirms the correctness and validity of all adopted theoretical assumptions.

An Approximate Method for Multidimensional Problems of Radiative Energy Transfer in an Absorbing and Emitting Media

1969 ◽  
Vol 91 (4) ◽  
pp. 502-510 ◽  
Author(s):  
L. R. Glicksman
Keyword(s):  
Energy Transfer ◽  
Approximate Method ◽  
Numerical Solutions ◽  
Radiant Energy ◽  
Radiative Energy ◽  
Parallel Plates ◽  
Radiative Energy Transfer ◽  
Multidimensional Problems ◽  
Concentric Cylinders ◽  
Emitting Media

A new approximate method for dealing with radiant energy transfer in an absorbing and emitting media is presented. The approximate equations reduce to the correct optically thin and thick limits for multidimensional problems. The technique is used to predict the heat transfer between plane parallel plates and between concentric cylinders for a gray medium in radiation equilibrium. The results are in excellent agreement with previously published numerical solutions for all values of the optical thickness.

Low order high accuracy deformable mirror based on electromagnetic actuators

2007 ◽  
Author(s):  
François P. Wildi ◽  
Gabriel Mühlebach ◽  
Tony Maulaz
Keyword(s):  
High Accuracy ◽  
Deformable Mirror ◽  
Electromagnetic Actuators ◽  
Low Order

scholarly journals An Efficient Technique for solving Lane-Emden Equation

2020 ◽  
Vol 25 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Eman Hassan Ouda Alfrdji
Keyword(s):  
Exact Solutions ◽  
Approximate Method ◽  
Collocation Method ◽  
Initial Conditions ◽  
Operational Matrix ◽  
High Accuracy ◽  
Efficient Technique ◽  
Numerical Examples ◽  
Emden Equation ◽  
Boubaker Polynomials

       The orthogonal Boubaker polynomials and their operational matrix of derivatives were deduced, introduced a new efficient approximate method for solving Lane-Emden equation with initial conditions via collocation method. Some numerical examples were given to demonstrate the applicability of this method. The results have been compared with exact solutions to show that they achieved a high accuracy.

the effects of resonance with Jupiter in the system of short-period comets

1974 ◽  
Vol 22 ◽  
pp. 193-203
Author(s):  
L̆ubor Kresák
Keyword(s):  
Structural Effects ◽  
Order Resonance ◽  
Mean Motion ◽  
Short Period ◽  
The Mean ◽  
Compound Effect ◽  
Low Order

AbstractStructural effects of the resonance with the mean motion of Jupiter on the system of short-period comets are discussed. The distribution of mean motions, determined from sets of consecutive perihelion passages of all known periodic comets, reveals a number of gaps associated with low-order resonance; most pronounced are those corresponding to the simplest commensurabilities of 5/2, 2/1, 5/3, 3/2, 1/1 and 1/2. The formation of the gaps is explained by a compound effect of five possible types of behaviour of the comets set into an approximate resonance, ranging from quick passages through the gap to temporary librations avoiding closer approaches to Jupiter. In addition to the comets of almost asteroidal appearance, librating with small amplitudes around the lower resonance ratios (Marsden, 1970b), there is an interesting group of faint diffuse comets librating in characteristic periods of about 200 years, with large amplitudes of about±8% in μ and almost±180° in σ, around the 2/1 resonance gap. This transient type of motion appears to be nearly as frequent as a circulating motion with period of revolution of less than one half that of Jupiter. The temporary members of this group are characteristic not only by their appearance but also by rather peculiar discovery conditions.

A New 1,000 kV Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 260-261
Author(s):  
M. Nishigaki ◽  
S. Katagiri ◽  
H. Kimura ◽  
B. Tadano
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Basic Research ◽  
Chromatic Aberration ◽  
High Accuracy ◽  
Biological Specimen ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron

The high voltage electron microscope has many advantageous features in comparison with the ordinary electron microscope. They are a higher penetrating efficiency of the electron, low chromatic aberration, high accuracy of the selected area diffraction and so on. Thus, the high voltage electron microscope becomes an indispensable instrument for the metallurgical, polymer and biological specimen studies. The application of the instrument involves today not only basic research but routine survey in the various fields. Particularly for the latter purpose, the performance, maintenance and reliability of the microscope should be same as those of commercial ones. The authors completed a 500 kV electron microscope in 1964 and a 1,000 kV one in 1966 taking these points into consideration. The construction of our 1,000 kV electron microscope is described below.

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