Design concepts for a fast-readout low-noise CCD controller

1998 ◽  
Author(s):  
Rolf Gerdes ◽  
James W. Beletic ◽  
Raymond C. DuVarney
Keyword(s):  
Low Noise ◽  
Design Concepts

Influence of the Casing Width and the Impeller Position on Centrifugal Fan Performance: A CFD-Based Study on Cause and Effect

2014 ◽  
Author(s):  
S. Schönwald ◽  
F. Kameier ◽  
M. Böhle
Keyword(s):  
High Efficiency ◽  
Low Noise ◽  
Width Ratio ◽  
Centrifugal Fan ◽  
Noise Emission ◽  
Cfd Simulations ◽  
Fan Performance ◽  
Design Concepts ◽  
Impeller Outlet ◽  
Overall Efficiency

A high-efficiency centrifugal fan with low noise emission is used to investigate the influence of the casing width on the flow performance. Common design concepts use a width ratio of casing to impeller outlet from 2.5 up to 3. This range of the width ratio results in a large casing depth, which is not the best approach with regard to the overall dimension and the material costs for large industrial machines. Furthermore, centrifugal fan designs with a width ratio above 3 are disadvantageous because of their lower overall efficiency. In addition to an optimized casing depth, the position of the impeller in the casing also influences the performance. Using the results of several CFD simulations, we show that by creating a very small gap between the impeller rear plate and the casing wall, smaller energy losses and higher–performance can be achieved.

Development Testing of Epicyclic Gearing

1991 ◽  
Author(s):  
D. E. Yates ◽  
G. J. Lack
Keyword(s):  
Vibration Isolation ◽  
Industrial Applications ◽  
Low Noise ◽  
Test Rig ◽  
Innovative Design ◽  
Design Concepts ◽  
Low Weight ◽  
Design And Manufacturing ◽  
Manufacturing Methods ◽  
Dynamic Load Sharing

The increasing use of epicyclics for high powered marine and industrial applications has resulted in world wide interest in this type of gearing. The coaxial input and output, reduced losses, small size and low weight are some of the advantages. The use of a full size development test rig using the power circulation method has been fundamental to the evolution of double helical, flexible annulus epicyclics, and has led to a detailed understanding of their operating principles. This understanding has been essential for the analytical modelling and the development of innovative design concepts. The paper outlines some of the work which has been carried out in the test rig at NEI Allen Ltd - Allen Gears. The method of measuring the dynamic load sharing is discussed and some of the results which have led to improvements in the design and manufacturing methods are given. Test rig work continues currently with the development of low noise gears and vibration isolation.

Development of a Low Noise Pump by New Design Concept

2003 ◽  
Author(s):  
Kazuyoshi Miyagawa ◽  
Ryuichi Sato
Keyword(s):  
Noise Level ◽  
Three Dimensional ◽  
Low Noise ◽  
Operating Conditions ◽  
Design Concept ◽  
Design Concepts ◽  
Flow Noise ◽  
Cavitation Tunnel ◽  
Parametric Studies ◽  
Blade Row Interaction

The Japan Defense Agency is conducting a project to develop a cavitation tunnel, called the FNS (Flow Noise Simulator project) (1). The FNS was designed as a large cavitation tunnel with low background noise level to measure the noise of an object. In order to satisfy the low noise level for the FNS, it is important to develop a low noise pump. In the present study, several new design concepts were developed using CFD (Computational Fluid Dynamics) and these concepts and the pump performance were verified by model test. In developing low noise pump, it is important to avoid cavitation generation in all operating conditions. It is also important to reduce blade-passing influence due to blade row interaction between impeller and diffuser. To control unsteadiness by interaction, the axial gap between two blade rows was widened and viscous wake from the impeller was decreased. Many extensive parametric studies (e.g. blade sweep, number of blades) were conducted using three-dimensional CFD computations. The impeller developed for the FNS pump has seven blades, 4.3 m diameter and the stator downstream has nine blades. Several model tests were carried out to verify the design concept of the pump. It was confirmed that the noise level of the new design pump was decreased compared to a conventional industrial pump and efficiency was also improved.

Concept Design of a Low-Noise Industrial Engine

1989 ◽  
Vol 203 (4) ◽  
pp. 247-254
Author(s):  
J M Sawer ◽  
M D Ford-Dunn
Keyword(s):  
Low Noise ◽  
Concept Design ◽  
Design Concepts ◽  
Engine Design ◽  
Environmental Demands

A fundamental re-evaluation of industrial engine design concepts is made to take into account modern environmental demands. A range of diesel and gasoline powerplants, incorporating many low-noise features, is suggested.

Development Testing of Epicyclic Gearing

1992 ◽  
Vol 114 (2) ◽  
pp. 328-333 ◽  
Author(s):  
D. E. Yates ◽  
G. J. Lack
Keyword(s):  
Analytical Modeling ◽  
Vibration Isolation ◽  
Industrial Applications ◽  
Low Noise ◽  
Test Rig ◽  
Innovative Design ◽  
Design Concepts ◽  
Low Weight ◽  
Design And Manufacturing ◽  
Dynamic Load Sharing

The increasing use of epicyclics for high-powered marine and industrial applications has resulted in world-wide interest in this type of gearing. The coaxial input and output, reduced losses, small size, and low weight are some of the advantages. The use of a full-size development test rig using the power circulation method has been fundamental to the evolution of double helical, flexible annulus epicyclics, and has led to a detailed understanding of their operating principles. This understanding has been essential for the analytical modeling and the development of innovative design concepts. The paper outlines some of the work that has been carried out in the test rig at NEI Allen Ltd.—Allen Gears. The method of measuring the dynamic load sharing is discussed and some of the results that have led to improvements in the design and manufacturing methods are given. Test rig work continues currently with the development of low-noise gears and vibration isolation.

Distribution of R- and S-Process Elements in the Galactic Halo

1988 ◽  
Vol 132 ◽  
pp. 501-506
Author(s):  
C. Sneden ◽  
C. A. Pilachowski ◽  
K. K. Gilroy ◽  
J. J. Cowan
Keyword(s):  
Heavy Element ◽  
Galactic Halo ◽  
Low Noise ◽  
Heavy Elements ◽  
Process Synthesis ◽  
Element Abundances ◽  
Halo Stars ◽  
Abundance Patterns ◽  
R Process ◽  
Process Elements

Current observational results for the abundances of the very heavy elements (Z>30) in Population II halo stars are reviewed. New high resolution, low noise spectra of many of these extremely metal-poor stars reveal general consistency in their overall abundance patterns. Below Galactic metallicities of [Fe/H] Ã −2, all of the very heavy elements were manufactured almost exclusively in r-process synthesis events. However, there is considerable star-to-star scatter in the overall level of very heavy element abundances, indicating the influence of local supernovas on element production in the very early, unmixed Galactic halo. The s-process appears to contribute substantially to stellar abundances only in stars more metal-rich than [Fe/H] Ã −2.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Quality films from carbon fiber evaporation for thorough coverage of TEM grids

1988 ◽  
Vol 46 ◽  
pp. 418-419
Author(s):  
N. Tempel ◽  
M. C. Ledbetter
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Carbon Films ◽  
Low Noise ◽  
Vacuum Evaporation ◽  
High Yield ◽  
Good Adhesion ◽  
Noise Structure ◽  
Resolution Electron ◽  
Carbon Foils

Carbon films have been a support of choice for high resolution electron microscopy since the introduction of vacuum evaporation of carbon. The desirable qualities of carbon films and methods of producing them has been extensively reviewed. It is difficult to get a high yield of grids by many of these methods, especially if virtually all of the windows must be covered with a tightly bonded, quality film of predictable thickness. We report here a method for producing carbon foils designed to maximize these attributes: 1) coverage of virtually all grid windows, 2) freedom from holes, wrinkles or folds, 3) good adhesion between film and grid, 4) uniformity of film and low noise structure, 5) predictability of film thickness, and 6) reproducibility.Our method utilizes vacuum evaporation of carbon from a fiber onto celloidin film and grid bars, adhesion of the film complex to the grid by carbon-carbon contact, and removal of the celloidin by acetone dissolution. Materials must be of high purity, and cleanliness must be rigorously maintained.

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