This document provides an introduction to quantitative x-ray diffraction methods. It discusses that quantitative analysis aims to determine precise structural characteristics and phase proportions from experimental diffraction data. This requires accurate intensity measurements and careful sample preparation to produce uniformly sized, randomly oriented powder. Several quantitative methods are based on comparing intensity ratios between unknown and known internal standard peaks. The most effective methods involve modeling the entire diffraction pattern to duplicate the experimental pattern.
Atomic force microscope (AFM) is a scanning near-field tool for nanoscale investigation which was invented in 1986. Instead of using light or electron beam, AFM uses a sharp tip to ‘‘feel’’ samples. As the tip radius of curvature is on the order of nanometers, AFM can detect changes at a spatial resolution up to sub nanometer level. Compared to the optical microscope, AFM has a much higher spatial resolution which provides the ability to investigate ultrafine structure of samples and even map the distribution of single molecules.
As AFM utilizes direct contact between the tip and the sample, minimum or even no sample preparation is required.
Moreover, AFM can investigate samples in liquid which provides an opportunity to monitor samples close to their native surroundings. Further, AFM provides true 3D images. With optical and electron microscopies, only limited ranges in heights can be ‘‘in-focus’’ at any one time. Therefore, AFM can provide unique insight into the structure and functional behavior of materials. AFM is a versatile technique. Besides scanning the topography of a sample, it can also be used to investigate the mechanical properties of the sample as well as the interactions between the tip and the sample. AFM has been successfully applied in widespread branches of science and technology such as nanofabrication, material science, chemical and drug engineering, biotechnology and microbiology. As for above mentioned reasons, Atomic force microscope (AFM) is considered a useful tool for the nanoscale measurement in material-polymer science and engineering. AFM lacks the robust ability to chemically characterize materials.
Atomic force microscope (AFM) is a scanning near-field tool for nanoscale investigation which was invented in 1986. Instead of using light or electron beam, AFM uses a sharp tip to ‘‘feel’’ samples. As the tip radius of curvature is on the order of nanometers, AFM can detect changes at a spatial resolution up to sub nanometer level. Compared to the optical microscope, AFM has a much higher spatial resolution which provides the ability to investigate ultrafine structure of samples and even map the distribution of single molecules.
As AFM utilizes direct contact between the tip and the sample, minimum or even no sample preparation is required.
Moreover, AFM can investigate samples in liquid which provides an opportunity to monitor samples close to their native surroundings. Further, AFM provides true 3D images. With optical and electron microscopies, only limited ranges in heights can be ‘‘in-focus’’ at any one time. Therefore, AFM can provide unique insight into the structure and functional behavior of materials. AFM is a versatile technique. Besides scanning the topography of a sample, it can also be used to investigate the mechanical properties of the sample as well as the interactions between the tip and the sample. AFM has been successfully applied in widespread branches of science and technology such as nanofabrication, material science, chemical and drug engineering, biotechnology and microbiology. As for above mentioned reasons, Atomic force microscope (AFM) is considered a useful tool for the nanoscale measurement in material-polymer science and engineering. AFM lacks the robust ability to chemically characterize materials.
Comparative Study of Evolutionary Algorithms for the Optimum Design Of Thin B...jmicro
With the increasing levels of Electromagnetic pollution almost exponentially in this modern age of
Electronics reported and highlighted by numerous studies carried out by scientists from all over the world,
inspire engineers to concentrate their research for the optimum design of multilayer microwave absorber
considering various parameters which are inherently conflicting in nature. In this paper we mainly focus
on the comparative study of different Evolutionary algorithms for the optimum design of thin broadband (2-
20GHz) multilayer microwave absorber for oblique incidence (300
) considering arbitrary polarization of
the electromagnetic waves. Different models are presented and synthesized using various Evolutionary
algorithm namely Firefly algorithm (FA), Particle swarm optimization (PSO), Artificial bee colony
optimization (ABC) and the best simulated results are tabulated and compared with each others.
Physical Characterization of a Method for Production of High Stability Suspen...Editor IJCATR
Suspensions/Dispersions are encountered in a wide range of
applications, e.g., liquid abrasive cleaners, ceramics, medicines,
inks, paints….etc. In most cases it is necessary to keep the
suspension stable for the product lifetime. A new modified
differential sedimentation measuring system is suggested and used
to identify physical parameters affecting the sedimentation in
suspensions. The technique is discussed in details. It is found that
particle sizes as well as viscosity of continuous phase are the most
important factors governing the stability of a suspension. Empirical
relations are extracted to quantitatively describe the weight effect of
each factor. The modified measuring system shows good accuracy
enough to detect fluctuations in concentration of suspended
particles due to their Brownian diffusion, as well as the particles
concentrations in the stable suspension. This study confirmed the
fact that particles diameters measured by Zetasizer are much
greater than those measured by the transmission electron
microscope. This study presents a proposal for new technique for
particle size separation based on the differential sedimentation in
viscose fluids. This new method is a differential viscosity column.
The proposed size separation technique may help to separate
engineered nano-particles with higher resolution
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Ultrasonic guided wave techniques have great potential for structural health monitoring applications. Appropriate mode and frequency selection is the basis for achieving optimised damage monitoring performance.
In this paper, several important guided wave mode attributes are
introduced in addition to the commonly used phase velocity and group velocity dispersion curves while using the general corrosion problem as an example. We first derive a simple and generic wave excitability function based on the theory of normal mode expansion and the reciprocity theorem. A sensitivity dispersion curve is formulated based on the group velocity dispersion curve. Both excitability and sensitivity dispersion curves are verified with finite element simulations. Finally, a
goodness dispersion curve concept is introduced to evaluate the tradeoffs between multiple mode selection objectives based on the wave velocity, excitability and sensitivity.
Damage detection in cfrp plates by means of numerical modeling of lamb waves ...eSAT Journals
Abstract
The paper presents an application of modeling acoustic waves propagation in a carbon fiber reinforced plastic (CFRP) plates for
damage detection. This task is a part of non-destructive testing (NDT) methods which are very important in many industry
branches. Propagation of Lamb waves is modeled using three-dimensional finite element method by means of commercial
software. In the paper three different cases of plate structures with and without flaws are considered to present review of selected
methods for the detection of defects in time and frequency domain. These are comparisons of: A-scans, B-scans, dispersion
curves, spectrograms, scalograms and energy plots. Developed numerical model first has been validated by means of analytical
solution for isotropic plate.
Keywords: Lamb waves, non-destructive testing, finite element method, damage detection
APPLICATION OF TAGUCHI METHOD FOR PARAMETRIC STUDIES OF A FUNNEL SHAPED STRUC...ijmech
In this paper, attempt has been made to minimize sound reflection from the wall by using Taguchi’s method and to find optimal structure for the suggested test-section inside the cavitation tunnel. The suggested structure which was added to the test-section is funnel-shaped with a performance like a check valve. In order to obtain approximate values of five independent parameters, three levels were taken into account for each parameter. By combining parameters of different levels, 27 tests were designed using Taguchi’s method and Minitab Software. Different acoustic analyses were conducted in COMSOL Multiphysics software, and defined parameter of general reflection coefficient was obtained for 21 observer points. Applying the general reflection coefficients to Minitab Software and drawing the SNR graph, approximate values of the parameters were obtained. However, these values did not produce enough accuracy to design the optimal structure. For this reason, five levels around optimal values, obtained from the previous analysis, were considered for each parameter. Same steps were repeated again for the parameters at five
levels and optimal values were obtained. Optimal structure was modelled and analyzed. Consequently, appropriate defined parameters of general and local reflection coefficients were extracted which represented an optimal structure for the intended test section.
New folderelec425_2016_hw5.pdfMar 25, 2016 ELEC 425 S.docxcurwenmichaela
New folder/elec425_2016_hw5.pdf
Mar 25, 2016
ELEC 425 Spring 2016 HW 5 Questions
due in class on Tue Mar 31, 2016
1) Read Sec. 1.11 from the textbook. Use the conventions plotted on Fig. 1.42 to derive the TM
matrix in Eq. 1.253.
2) The file Tmatrix.m is a Matlab script that evaluates the reflection and transmission coefficients
for TE and TM polarizations. Analyze the code, and write a script that uses Tmatrix.m to
generate Fig. 3 from Winn1998.pdf file. When the output from the Matlab code is overlaid with
Fig. 3 from the paper, they should match exactly as shown below. Note the dB scale in the
figure.
3) Read the following tutorial from the Lumerical website.
https://kb.lumerical.com/en/diffractive_optics_stack.html
First, run and verify the tutorial. Then, modify the tutorial files so that you simulate 0° and 45°
results from Fig. 3 of the Winn1998.pdf paper as shown above. The structure is composed of a
total of 12 layers: air on the entrance and exit sides, and five repetitions of two quarter wave
(𝑑1 + 𝑑2 =
𝜆1
4
+
𝜆2
4
= 𝑎) layers of refractive index 𝑛1 = 1.7 and 𝑛2 = 3.4 and thicknesses 𝑑1
and 𝑑2. Export your simulation results, import them into Matlab, and plot the output from part
2) with the output from Lumerical FDTD on the same plot. Verify that FDTD code results in a
similar set of results.
Please hand in your derivations, your plots and the relevant code used to generate the plots all
stapled together.
You can find the required files under the Handouts section on the course website at:
http://courses.ku.edu.tr/elec425
https://kb.lumerical.com/en/diffractive_optics_stack.html
http://courses.ku.edu.tr/elec425
New folder/PhotonicsLaserEngineering.pdf.part
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
Overview combining ab initio with continuum theoryDierk Raabe
Multi-methodological approaches combining quantum-mechanical and/or atomistic simulations
with continuum methods have become increasingly important when addressing multi-scale phenomena in
computational materials science. A crucial aspect when applying these strategies is to carefully check,
and if possible to control, a variety of intrinsic errors and their propagation through a particular multimethodological
scheme. The first part of our paper critically reviews a few selected sources of errors
frequently occurring in quantum-mechanical approaches to materials science and their multi-scale propagation
when describing properties of multi-component and multi-phase polycrystalline metallic alloys.
Our analysis is illustrated in particular on the determination of i) thermodynamic materials properties at
finite temperatures and ii) integral elastic responses. The second part addresses methodological challenges
emerging at interfaces between electronic structure and/or atomistic modeling on the one side and selected
continuum methods, such as crystal elasticity and crystal plasticity finite element method (CEFEM and
CPFEM), new fast Fourier transforms (FFT) approach, and phase-field modeling, on the other side.