Measurement of Nonuniform Stresses in Semiconductors by the Micro-Raman Method

1997 ◽  
Vol 505 ◽  
Author(s):  
K. Pinardi ◽  
S. C. Jain ◽  
H. E. Maes ◽  
R. Van Overstraeten ◽  
M. Willander ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Laser Beam ◽  
Penetration Depth ◽  
Raman Spectra ◽  
Excellent Agreement ◽  
Large Volume ◽  
Strain Distribution ◽  
Laser Light ◽  
Experimental Results

ABSTRACTMicro-Raman measurements axe performed with a focused laser beam. Because of its finite diameter (∼ 1 μm) and penetration depth, the laser beam samples a “large volume” of the sample. In a nonuniformly strained sample, spectra originating from different points are different. Therefore the observed spectrum depends on both the strain distribution in the sample and the absorption coefficient of the laser light. We describe a method to calculate the Raman spectra taking these factors into account. The calculated spectra show excellent agreement with the experimental results.

Convective Losses From Cavity Solar Receivers—Comparisons Between Analytical Predictions and Experimental Results

1983 ◽  
Vol 105 (1) ◽  
pp. 29-33 ◽  
Author(s):  
A. M. Clausing
Keyword(s):  
Experimental Data ◽  
Experimental Evidence ◽  
Analytical Model ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Refined Model ◽  
Wall Area

Cavity solar receivers are generally believed to have higher thermal efficiencies than external receivers due to reduced losses. A simple analytical model was presented by the author which indicated that the ability to heat the air inside the cavity often controls the convective loss from cavity receivers. Thus, if the receiver contains a large amount of inactive hot wall area, it can experience a large convective loss. Excellent experimental data from a variety of cavity configurations and orientations have recently become available. These data provided a means of testing and refining the analytical model. In this manuscript, a brief description of the refined model is presented. Emphasis is placed on using available experimental evidence to substantiate the hypothesized mechanisms and assumptions. Detailed comparisons are given between analytical predictions and experimental results. Excellent agreement is obtained, and the important mechanisms are more clearly delineated.

Experimental results on the photophoretic motion and radiometric trapping of particles by irradiation with laser light

1988 ◽  
Vol 47 (3) ◽  
pp. 247-250 ◽  
Author(s):  
S. De Nicola ◽  
A. Finizo ◽  
P. Mormile ◽  
G. Pierattini ◽  
S. Martellucci ◽  
...  
Keyword(s):  
Laser Light ◽  
Experimental Results

Raman spectra of CN vibrations of acetonitrile in aqueous and other solutions. Experimental results andab initio calculations

2005 ◽  
Vol 36 (10) ◽  
pp. 932-937 ◽  
Author(s):  
F. H. Tukhvatullin ◽  
A. Jumabaev ◽  
G. Muradov ◽  
H. A. Hushvaktov ◽  
A. A. Absanov
Keyword(s):  
Raman Spectra ◽  
Experimental Results

RAMAN SPECTRA OF THE H2SO4–SO3 AND D2SO4–SO3 SYSTEMS: EVIDENCE FOR THE OCCURRENCE OF POLYSULPHURIC ACIDS

1962 ◽  
Vol 40 (4) ◽  
pp. 658-674 ◽  
Author(s):  
R. J. Gillespie ◽  
E. A. Robinson
Keyword(s):  
Sulphuric Acid ◽  
Raman Spectra ◽  
Ionic Species ◽  
The Self ◽  
Experimental Results ◽  
Similar Work ◽  
Stretching Vibrations ◽  
Sulphur Trioxide ◽  
High Concentrations

The Raman spectra of oleums, i.e. mixtures of sulphur trioxide and sulphuric acid, have been re-examined. Similar measurements on the sulphur trioxide – deuterosulphuric acid (D2SO4) system are also reported. The experimental results and conclusions of previous similar work on oleums are discussed. By comparison of the spectra of oleums with those of the polysulphuryl halides it is shown that the polysulphuric acids H2S2O7 and H2S3O10 are present in this system. The increase in the frequency of the SO2 stretching vibrations with increasing concentration of sulphur trioxide gives evidence for the existence of higher polysulphuric acids such as H2S4O13 at high concentrations of sulphur trioxide. In relatively concentrated oleum, sulphur trioxide monomer and trimer are also present. It is shown that the self-dissociation of liquid H2S2O7 gives mainly molecular H2S2O10 and H2SO4 and not ionic species. The conclusions reached from the interpretation of the Raman spectra of the D2SO4–SO3 system are similar to those arrived at for sulphuric acid oleums. The spectra of solutions of NaHSO4 in oleums were also examined, and are discussed.

scholarly journals Spectroscopic closed loop control of penetration depth in laser beam welding process

2012 ◽  
Author(s):  
Teresa Sibillano ◽  
Antonio Ancona ◽  
Domenico Rizzi ◽  
Francesco Mezzapesa ◽  
Ali Riza Konuk ◽  
...  
Keyword(s):  
Laser Beam ◽  
Penetration Depth ◽  
Closed Loop ◽  
Laser Beam Welding ◽  
Welding Process ◽  
Closed Loop Control ◽  
Loop Control

scholarly journals The use of laser biostimulation in human and animal physiotherapy – a review

2017 ◽  
Vol 86 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Paulina Zielińska ◽  
Maria Soroko ◽  
Anna Zwyrzykowska ◽  
Zdzisław Kiełbowicz
Keyword(s):  
Veterinary Medicine ◽  
Laser Beam ◽  
Laser Treatment ◽  
Laser Therapy ◽  
Laser Light ◽  
Regenerative Processes ◽  
Physical Methods ◽  
Animal Organism ◽  
Positive Effect ◽  
Class Iv

Laser biostimulation involves applying a laser beam to the tissue to facilitate healing and regenerative processes. Laser therapy is one of the most important physical methods used in human physiotherapy. In veterinary medicine, laser therapy is a new and so far poorly examined method. The results of studies conducted so far are very promising, yet the positive effect of laser light, especially that of class IV, has yet to be confirmed. This article presents an overview of the available literature on the effect of laser treatment on the human and animal organism.

Non-Linear Dynamic Magneto Electric Effects in Ferromagnetic-Ferroelectric Layered Composites

2013 ◽  
Author(s):  
Satenik Harutyunyan ◽  
Davresh Hasanyan
Keyword(s):  
Vibration Frequency ◽  
Strain Distribution ◽  
Longitudinal Vibration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Structure Design ◽  
Experimental Results ◽  
Physical Parameters ◽  
Wide Range ◽  
Non Linear

A non-linear theoretical model including bending and longitudinal vibration effects was developed for predicting the magneto electric (ME) effects in a laminate bar composite structure consisting of magnetostrictive and piezoelectric multi-layers. If the magnitude of the applied field increases, the deflection rapidly increases and the difference between experimental results and linear predictions becomes large. However, the nonlinear predictions based on the present model well agree with the experimental results within a wide range of applied electric field. The results of the analysis are believed to be useful for materials selection and actuator structure design of actuator in actuator fabrication. It is shown that the problem for bars of symmetrical structure is not divided into a plane problem and a bending problem. A way of simplifying the solution of the problem is found by an asymptotic method. After solving the problem for a laminated bar, formula that enable one to change from one-dimensional required quantities to three dimensional quantities are obtained. The derived analytical expression for ME coefficients depend on vibration frequency and other geometrical and physical parameters of laminated composites. Parametric studies are presented to evaluate the influences of material properties and geometries on strain distribution and the ME coefficient. Analytical expressions indicate that the vibration frequency strongly influences the strain distribution in the laminates, and that these effects strongly influence the ME coefficients. It is shown that for certain values of vibration frequency (resonance frequency), the ME coefficient becomes infinity; as a particular case, low frequency ME coefficient were derived as well.

In-process determination of laser beam absorption coefficient for laser-assisted turning processes

2017 ◽  
Vol 92 (5-8) ◽  
pp. 2929-2938 ◽  
Author(s):  
Mostafa M. Kashani ◽  
Mohammad R. Movahhedy ◽  
Mohammad T. Ahmadian ◽  
Reza S. Razavi
Keyword(s):  
Absorption Coefficient ◽  
Laser Beam ◽  
Laser Assisted Turning

Improving the K-Means Clustering Algorithm Oriented to Big Data Environments

2021 ◽  
pp. 289-308
Author(s):  
Joaquín Pérez Ortega ◽  
Nelva Nely Almanza Ortega ◽  
Andrea Vega Villalobos ◽  
Marco A. Aguirre L. ◽  
Crispín Zavala Díaz ◽  
...  
Keyword(s):  
Big Data ◽  
Text Mining ◽  
Large Volume ◽  
Execution Time ◽  
Clustering Algorithm ◽  
Efficient Algorithms ◽  
Experimental Results ◽  
Digital Format ◽  
Basic Approaches ◽  
Previous Iteration

In recent years, the amount of texts in natural language, in digital format, has had an impressive increase. To obtain useful information from a large volume of data, new specialized techniques and efficient algorithms are required. Text mining consists of extracting meaningful patterns from texts; one of the basic approaches is clustering. The most used clustering algorithm is k-means. This chapter proposes an improvement of the k-means algorithm in the convergence step; the process stops whenever the number of objects that change their assigned cluster in the current iteration is bigger than the ones that changed in the previous iteration. Experimental results showed a reduction in execution time up to 93%. It is remarkable that, in general, better results are obtained when the volume of the text increase, particularly in those texts within big data environments.

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