A combined Doppler and time-of-flight laser anemometer for measurement of density fluctuations in plasmas

1996 ◽  
Vol 58 (8-9) ◽  
pp. 1013-1019 ◽  
Author(s):  
L. Lading ◽  
M. Saffman ◽  
S.G. Hanson ◽  
R.V. Edwards
Keyword(s):  
Time Of Flight ◽  
Density Fluctuations ◽  
Laser Anemometer

Time-of-flight laser anemometer for velocity measurements in the atmosphere

1978 ◽  
Vol 17 (10) ◽  
pp. 1486_1 ◽  
Author(s):  
L. Lading ◽  
A. Skov Jensen ◽  
C. Fog ◽  
H. Andersen
Keyword(s):  
Time Of Flight ◽  
Velocity Measurements ◽  
Laser Anemometer

scholarly journals Laser Anemometry Techniques for Turbine Applications

1987 ◽  
Author(s):  
Mark P. Wernet ◽  
Lawrence G. Oberle
Keyword(s):  
Turbulent Flows ◽  
Time Of Flight ◽  
Nasa Lewis Research ◽  
Acceptance Angle ◽  
Flight System ◽  
Laser Anemometry ◽  
Laser Anemometer ◽  
Highly Turbulent Flows ◽  
Anemometer System ◽  
Comparison Measurements

Laser anemometry offers a nonintrusive means for obtaining flow field information. Our current research efforts at NASA Lewis Research Center are focused on instrumenting a warm turbine facility with a laser anemometer system. In an effort to determine the laser anemometer system best qualified for the warm turbine environment, we compared the performance of a conventional laser fringe anemometer and a two spot time-of-flight system with a new, modified time-of-flight system, called a Four Spot laser anemometer. The comparison measurements were made in highly turbulent flows near walls. The Four Spot anemometer uses elliptical spots to increase the flow acceptance angle to be comparable to that of a Laser Fringe Anemometer. Also, the Four Spot uses an optical code that vastly simplifies the pulse detection processor. The results of the comparison measurements will exemplify which laser anemometer system is best suited to the hostile environment typically encountered in warm rotating turbomachinery.

Implementation of a new type of time-of-flight laser anemometer

1986 ◽  
Vol 25 (5) ◽  
pp. 644 ◽  
Author(s):  
Mark P. Wernet ◽  
Robert V. Edwards
Keyword(s):  
Time Of Flight ◽  
Laser Anemometer ◽  
New Type

INTERACTIONS AND SCATTERING IN d = 1 STRING THEORY

1991 ◽  
Vol 06 (16) ◽  
pp. 1465-1477 ◽  
Author(s):  
GAUTAM MANDAL ◽  
ANIRVAN M. SENGUPTA ◽  
SPENTA R. WADIA
Keyword(s):  
String Theory ◽  
Analytic Continuation ◽  
Time Of Flight ◽  
Density Fluctuations ◽  
Tree Level ◽  
Point Function

We discuss two results: (i) we calculate the two-point function of the density fluctuations to [Formula: see text] in the fermonic formulation of the d = 1 string theory and compare with the [Formula: see text] result from the candidate collective field Hamiltonian. The latter result is divergent, showing the inequivalence of the two theories. We find out the corrections to the collective field Hamiltonian (both in the form of infinite counterterms and additional finite pieces) needed to match with the fermion theory. (ii) We study tree-level scattering processes between bosons due to the localized interaction near the boundary (in a region of order [Formula: see text]). The reflection problem at the boundary is treated by an analytic continuation of the time-of-flight variable.

Applications of Time-OF-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

1990 ◽  
Vol 48 (2) ◽  
pp. 308-309
Author(s):  
Bruno Schueler ◽  
Robert W. Odom
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Structural Information ◽  
Time Of Flight ◽  
Biological Tissues ◽  
Polymer Surfaces ◽  
Tof Sims ◽  
Secondary Ions ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.

Assessment of extracranial-intracranial bypass in Moyamoya disease using 3T time-of-flight MR angiography: Comparison with CT angiography

VASA ◽  
2014 ◽  
Vol 43 (4) ◽  
pp. 278-283 ◽  
Author(s):  
Qian Chen ◽  
Rongfeng Qi ◽  
Xiaoqing Cheng ◽  
Changsheng Zhou ◽  
Song Luo ◽  
...  
Keyword(s):  
Image Quality ◽  
Moyamoya Disease ◽  
Mr Angiography ◽  
Time Of Flight ◽  
Consecutive Series ◽  
Tof Mra ◽  
Bypass Patency ◽  
Significant Difference ◽  
Contrast Technique ◽  
Vessel Integrity

Background: To evaluate the value of time-of-flight MR angiography (TOF MRA) for the assessment of extracranial-intracranial (EC-IC) bypass in Moyamoya disease in comparison with computed tomography angiography (CTA). Patients and methods: A consecutive series of 23 patients with Moyamoya disease were analyzed retrospectively. Twenty three patients underwent 25 procedures of extracranial-intracranial bypass. Cranial CTA was performed within one week after the surgery to assess bypass patency. Then TOF MRA was scanned within 24 h after CTA on a 3T MRI system. Using 5-point scales (0 = poor to 4 = excellent), two radiologists rated the image quality and vessel integrity of bypass for three segments (extracranial, trepanation, intracranial). Results: Image quality was high in both CTA and TOF MRA (mean quality score 3.84 ± 0.37 and 3.8 ± 0.41), without statistical difference (p = 0.66). Mean scores of TOF MRA with respect to bypass visualization were higher than CTA in the intracranial segment (p = 0.026). No significant difference of bypass visualization regarding the extracranial and trepanation segments was found between TOF MRA and CTA (p = 0.66 and p = 0.34, respectively). For the trepanation segment, TOF MRA showed pseudo lesions in 2 of all 25 cases. Conclusions: 3T TOF MRA, a non-contrast technique not exposing the patients to radiation, proved to be at least equal to CTA for the assessment of EC-IC bypass, and even superior to CTA with respect to the intracranial segment. In addition, readers should be aware of a potential overestimation showing focal pseudo lesions of the bypass at the trepanation segment in TOF MRA.

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