The document describes the design and construction of a high-resolution 3D translation stage for a scanning tunneling microscope (STM) equipped with a newly developed capacitive translation sensor. Key points:
1) The sensor can measure translations in the lateral and perpendicular directions with sub-angstrom resolution.
2) In combination with a model-based digital feedback system, the sensor and stage will enable accurate probe positioning and control, making the STM suitable for metrological applications.
3) The capacitive sensor can detect translations in three dimensions with resolutions of 30 picometers laterally and 10 picometers perpendicular to the surface.
This paper presents an approach for image restoration in the presence of blur and noise. The image is divided into independent regions modeled with a Gaussian prior. Wavelet-based methods are used for image denoising, while classical Wiener filtering is used for deblurring. The algorithm finds the maximum a posteriori estimate at the intersection of convex sets generated by Wiener filtering. It provides efficient image restoration without sacrificing the simplicity of filtering, and generates a better restored image compared to previous methods.
This document describes an experiment that demonstrates sub-Rayleigh resolution in imaging by using N-photon detection with a single-photon avalanche detector array. A focused laser beam is scanned over an object in an arbitrary pattern unknown to the imager. Pixels registering exactly N photon counts are used to form an image, improving resolution by a factor of (N - maximum average photon number)1/2 beyond the Rayleigh diffraction limit. The experiment images a resolution target and resolves stripes below the Rayleigh resolution with N=23 photon detection, in agreement with theory.
1. Quantitative NMR (qNMR) allows for both relative and absolute concentration determination of compounds in a mixture. It requires optimizing acquisition parameters and using an internal concentration standard for absolute quantification.
2. For relative quantification, integral ratios are used to determine molar ratios without needing a standard. For absolute quantification, integrals are compared to a known standard concentration to determine unknown concentrations.
3. Many factors must be controlled for accurate qNMR including sample preparation, acquisition parameters like relaxation delay and digital resolution, processing techniques, and analysis methods for relative or absolute quantification.
Reconstruction of magnetic source images using the Wiener filter and a multic...Miltão Ribeiro
A system for imaging magnetic surfaces using a magnetoresistive sensor array is developed. The experimental setup is composed of a linear array of 12 sensors uniformly spaced, with sensitivity of 150 pT∗Hz^{−1/2} at 1 Hz, and it is able to scan an area of (16 × 18) cm^{2} from a separation of 0.8 cm of the sources with a resolution of 0.3 cm. Moreover, the point spread function of the multi-sensor system is also studied, in order to characterize its transference function and to improve the quality in the restoration of images. Furthermore, the images are generated by mapping the response of the sensors due to the presence of phantoms constructed of iron oxide, which are magnetized by a pulse
of 80 mT. The magnetized phantoms are linearly scanned through the sensor array and the remanent magnetic field is acquired and displayed in gray levels using a PC. The images of the magnetic sources are reconstructed using two-dimensional generalized parametric Wiener filtering. Our results exhibit a very good capability to determine the spatial distribution of magnetic field sources, which produce magnetic fields of low intensity.
Publication Name: Review of Scientific Instruments.
Author: J. A. Leyva-Cruz, E. S. Ferreira, M. S. R. Miltão, A. V. Andrade-Neto, A. S. Alves, J. C. Estrada, and M. E. Cano.
You will find here all the elements presented by the CENAPT team ( Drs. Guido Pauli and Charlotte Simmler) and pertaining to the NMR workshop at the American Society of Pharmacognosy (ASP 2017, Portland Oregon).
These slides summarize the different steps related to the implementation of quantitative NMR for purity analysis.
Noise Reduction in Magnetic Resonance Images using Wave Atom ShrinkageCSCJournals
This document discusses noise reduction in magnetic resonance images using wave atom shrinkage. It proposes using wave atom transforms to enhance noisy MRI images. Wave atom transforms can sparsely represent anisotropic patterns better than other transforms like wavelets and curvelets. The paper compares wave atom shrinkage to other approaches like wavelet and curvelet domain denoising. It finds that wave atom shrinkage improves signal-to-noise ratio in MRI images, especially for low signal-to-noise ratio images, more effectively than other approaches.
High resolution bound-fluid, free-fluid and total porosity wamrhaggag
This document discusses techniques for obtaining high-resolution estimates of total porosity, bound fluid, and free fluid volumes from NMR well logging data. It describes a processing method called "alpha processing" that uses a high-resolution measurement to refine a lower-resolution estimate. The method is applied to NMR data to provide property estimates with the maximum tool resolution of about 9 inches. Examples are given showing how the technique can identify thin laminations and determine quantitative fluid volumes in different beds.
Segmentation Based Multilevel Wide Band Compression for SAR Images Using Coif...CSCJournals
Synthetic aperture radar (SAR) data represents a significant resource of information for a large variety of researchers. Thus, there is a strong interest in developing data encoding and decoding algorithms which can obtain higher compression ratios while keeping image quality to an acceptable level. In this work, results of different wavelet-based image compression and segmentation based wavelet image compression are assessed through controlled experiments on synthetic SAR images. The effects of dissimilar wavelet functions, number of decompositions are examined in order to find optimal family for SAR images. The choice of optimal wavelets in segmentation based wavelet image compression is coiflet for low frequency and high frequency component. The results presented here is a good reference for SAR application developers to choose the wavelet families and also it concludes that wavelets transform is rapid, robust and reliable tool for SAR image compression. Numerical results confirm the potency of this approach.
This paper presents an approach for image restoration in the presence of blur and noise. The image is divided into independent regions modeled with a Gaussian prior. Wavelet-based methods are used for image denoising, while classical Wiener filtering is used for deblurring. The algorithm finds the maximum a posteriori estimate at the intersection of convex sets generated by Wiener filtering. It provides efficient image restoration without sacrificing the simplicity of filtering, and generates a better restored image compared to previous methods.
This document describes an experiment that demonstrates sub-Rayleigh resolution in imaging by using N-photon detection with a single-photon avalanche detector array. A focused laser beam is scanned over an object in an arbitrary pattern unknown to the imager. Pixels registering exactly N photon counts are used to form an image, improving resolution by a factor of (N - maximum average photon number)1/2 beyond the Rayleigh diffraction limit. The experiment images a resolution target and resolves stripes below the Rayleigh resolution with N=23 photon detection, in agreement with theory.
1. Quantitative NMR (qNMR) allows for both relative and absolute concentration determination of compounds in a mixture. It requires optimizing acquisition parameters and using an internal concentration standard for absolute quantification.
2. For relative quantification, integral ratios are used to determine molar ratios without needing a standard. For absolute quantification, integrals are compared to a known standard concentration to determine unknown concentrations.
3. Many factors must be controlled for accurate qNMR including sample preparation, acquisition parameters like relaxation delay and digital resolution, processing techniques, and analysis methods for relative or absolute quantification.
Reconstruction of magnetic source images using the Wiener filter and a multic...Miltão Ribeiro
A system for imaging magnetic surfaces using a magnetoresistive sensor array is developed. The experimental setup is composed of a linear array of 12 sensors uniformly spaced, with sensitivity of 150 pT∗Hz^{−1/2} at 1 Hz, and it is able to scan an area of (16 × 18) cm^{2} from a separation of 0.8 cm of the sources with a resolution of 0.3 cm. Moreover, the point spread function of the multi-sensor system is also studied, in order to characterize its transference function and to improve the quality in the restoration of images. Furthermore, the images are generated by mapping the response of the sensors due to the presence of phantoms constructed of iron oxide, which are magnetized by a pulse
of 80 mT. The magnetized phantoms are linearly scanned through the sensor array and the remanent magnetic field is acquired and displayed in gray levels using a PC. The images of the magnetic sources are reconstructed using two-dimensional generalized parametric Wiener filtering. Our results exhibit a very good capability to determine the spatial distribution of magnetic field sources, which produce magnetic fields of low intensity.
Publication Name: Review of Scientific Instruments.
Author: J. A. Leyva-Cruz, E. S. Ferreira, M. S. R. Miltão, A. V. Andrade-Neto, A. S. Alves, J. C. Estrada, and M. E. Cano.
You will find here all the elements presented by the CENAPT team ( Drs. Guido Pauli and Charlotte Simmler) and pertaining to the NMR workshop at the American Society of Pharmacognosy (ASP 2017, Portland Oregon).
These slides summarize the different steps related to the implementation of quantitative NMR for purity analysis.
Noise Reduction in Magnetic Resonance Images using Wave Atom ShrinkageCSCJournals
This document discusses noise reduction in magnetic resonance images using wave atom shrinkage. It proposes using wave atom transforms to enhance noisy MRI images. Wave atom transforms can sparsely represent anisotropic patterns better than other transforms like wavelets and curvelets. The paper compares wave atom shrinkage to other approaches like wavelet and curvelet domain denoising. It finds that wave atom shrinkage improves signal-to-noise ratio in MRI images, especially for low signal-to-noise ratio images, more effectively than other approaches.
High resolution bound-fluid, free-fluid and total porosity wamrhaggag
This document discusses techniques for obtaining high-resolution estimates of total porosity, bound fluid, and free fluid volumes from NMR well logging data. It describes a processing method called "alpha processing" that uses a high-resolution measurement to refine a lower-resolution estimate. The method is applied to NMR data to provide property estimates with the maximum tool resolution of about 9 inches. Examples are given showing how the technique can identify thin laminations and determine quantitative fluid volumes in different beds.
Segmentation Based Multilevel Wide Band Compression for SAR Images Using Coif...CSCJournals
Synthetic aperture radar (SAR) data represents a significant resource of information for a large variety of researchers. Thus, there is a strong interest in developing data encoding and decoding algorithms which can obtain higher compression ratios while keeping image quality to an acceptable level. In this work, results of different wavelet-based image compression and segmentation based wavelet image compression are assessed through controlled experiments on synthetic SAR images. The effects of dissimilar wavelet functions, number of decompositions are examined in order to find optimal family for SAR images. The choice of optimal wavelets in segmentation based wavelet image compression is coiflet for low frequency and high frequency component. The results presented here is a good reference for SAR application developers to choose the wavelet families and also it concludes that wavelets transform is rapid, robust and reliable tool for SAR image compression. Numerical results confirm the potency of this approach.
This document discusses approaches for improving nonuniformity correction (NUC) for resistive array infrared scene projectors. Current NUC schemes treat each pixel independently, but scene-based effects like power drops and thermal crosstalk across the array are important to consider. The document examines potential problems with scene-based correction and discusses algorithms that could be used, such as accounting for far-field diffraction effects between pixels. It also describes the current sparse array approach used to measure each pixel's response and derive nonuniformity correction curves.
This document provides an overview of Coherent X-ray Diffraction Imaging (CXDI) and its application to nanostructures. CXDI allows imaging of a sample without using lenses by measuring the diffraction pattern and reconstructing the image using iterative phase retrieval algorithms. The document discusses coherent scattering from finite size crystals, partially coherent illumination, and experimental examples of CXDI for studying crystalline structures at the nanoscale.
This document summarizes an experimental study that measured the saturation thickness of granite and glass materials using gamma backscattering. Gamma backscattering is a non-destructive testing technique that can determine material thickness and density by detecting gamma photons backscattered from within a material. The experiment used a 137Cs radioactive source and gamma spectroscopy system to measure the backscattered gamma photon count rates from granite and glass slabs of increasing thickness. The results were analyzed to estimate the saturation thickness for each material, above which increasing thickness does not significantly increase the backscattered count rate.
Image Quality, Artifacts and it's Remedies in CT-Avinesh ShresthaAvinesh Shrestha
CT is one of the frequently used diagnostic imaging modalities in Radiology. Knowledge about image quality and artifacts is essential when diagnosing a patient with the help of CT images. Moreover, Radiology Technologist's should be very well aware about the ways to identify and eliminate or minimize the artifacts in CT for better image quality.
Monte carlo Technique - An algorithm for Radiotherapy CalculationsSambasivaselli R
Monte Carlo techniques are used to simulate particle transport through complex geometries to calculate dose distributions. The key steps are: (1) sampling the distance to the next interaction, interaction type, and energy/direction of secondary particles, (2) tracking particle histories through condensed histories or splitting/Russian roulette, and (3) calculating dose deposition in voxels. While fully accurate, Monte Carlo is statistically limited by the number of histories. Variance reduction techniques increase efficiency but introduce weighting factors. Overall uncertainty is typically within 3% given proper commissioning and cross-section libraries.
EXPERIMENTAL RESEARCH OF HIGHLY RELIABLE METHODS OF HYDROACOUSTIC COMMUNICATI...sipij
This document summarizes experimental research on reliable hydroacoustic communication methods for confined bodies of water with low sound absorption and complex reverberation patterns. Experiments were conducted in a metal tank to test multi-frequency signals. Orthogonal frequency-division multiplexing signals modulated with pseudo-noise sequences were used. Time differences of arrival between transmitters were determined with an accuracy of a few samples by identifying the direct ray before the global maximum. Histograms of delays between direct and maximum rays showed distributions over limited ranges. The methods allowed reliable positioning with equipment using a 96 kHz sampling frequency in such confined long-reverberating environments.
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.
This document describes research on using near-infrared optical imaging techniques for 3D biological tissue imaging. It discusses diffuse optical tomography (DOT) and fluorescence DOT (F-DOT). For DOT, it covers the photon diffusion equation, forward and inverse models, and finite element method implementation. For F-DOT, it discusses the fluorescence transport equations and parallel inversion schemes. Simulation results using MATLAB and NIRFAST show reconstructed optical property maps and fluorescence distributions in 2D and 3D geometries. Future work aims to further develop 3D imaging software for interfacing with DOT instrumentation.
This document discusses factors that impact the image quality in CT scans. It describes key scanning parameters like milliampere, scan time, slice thickness, and reconstruction algorithm that determine image quality. Higher mA and shorter scan times improve image quality but increase radiation dose. Thinner slice thickness and smaller pixel size enhance spatial resolution. The modulation transfer function is used to evaluate a system's ability to resolve fine detail spatially. Selection of these parameters requires balancing optimal image quality with minimizing radiation dose to the patient.
1) The document discusses methods for improving the sensitivity of electronic support measure (ESM) receivers through post-integration processing using autocorrelation and cross-correlation.
2) Autocorrelation processing takes advantage of the periodic nature of radar signals to improve detection of high repetition frequency signals. It provides a sensitivity gain that depends on the integration window and pulse repetition interval.
3) Three estimators are examined for extracting radar parameters: a straightforward method, interpolation method, and maximum likelihood method, with the maximum likelihood method providing the best accuracy.
This document analyzes various wavelet transforms for edge detection in X-ray bone images. It begins with an introduction to edge detection and its importance in medical imaging. Classical derivative operators can detect edges but also extract false information and are sensitive to noise. Wavelet transforms offer multi-resolution analysis to detect edges at different scales. The document then provides background on wavelet theory and discrete wavelet transforms. It analyzes applying various orthogonal wavelets like Haar, Daubechies, and Coiflet to X-ray images and compares their performance in edge detection based on metrics like edge detection accuracy and computation time. Haar wavelets performed best at detecting edges with better quality in less time.
Applications for high speed Raman Microscopynweavers
The RAMAN-11 is a new generation of laser Raman microscope developed by Nanophoton that enables the fastest high definition Raman imaging. It combines laser microscope and Raman spectroscopy technologies. The RAMAN-11's imaging speed is 300-600 times faster than competitors and it opens up new applications. Its software supports rapid data acquisition and robust analysis functions.
Sub-windowed laser speckle image velocimetry by fast fourier transform technique
Abstract
In this work, laser speckle velocimetry, a unique optical method for velocity measurement of fluid flow has been described. A laser sheet is developed and is illuminated on microscopic seeded particles to produce the speckle pattern at the recording plane. Double frame- single-exposure speckle images are captured in such a way that the second speckle image is shifted exactly in a known direction. The auto-correlation method has the ambiguity of direction of flow. To rectify this, spatial shift of the second image has been premeditated. Cross-correlation of sub interrogation areas is obtained by Fast Fourier Transform technique. Four sub-windows processed to obtain the velocity information with vector map analysis precisely.
This document discusses and compares two techniques for image denoising using wavelet transforms: Dual-Tree Complex DWT and Double-Density Dual-Tree Complex DWT. Both techniques decompose an image corrupted by noise using filter banks, apply thresholding to the wavelet coefficients, and reconstruct the image. The Double-Density Dual-Tree Complex DWT yields better denoising results than the Dual-Tree Complex DWT as it produces more directional wavelets and is less sensitive to shifts and noise variance. Experimental results on test images demonstrate that the Double-Density method achieves higher peak signal-to-noise ratios, especially at higher noise levels.
1999 observation of zero creep in piezoelectric actuatorspmloscholte
The document summarizes experiments on piezoelectric actuators that observe zero creep in certain locations of the hysteresis loop. Specifically:
1) Relaxation experiments using an offset sinusoidal voltage found relaxation increased hysteresis loop tilt but did not reduce hysteresis. Zero creep was observed at hysteresis loop extremum.
2) Creep experiments varying delay time also increased loop tilt but zero creep locations did not change and coincided with points where loop slope equaled virgin curve slope.
3) Increasing input voltage amplitude did not affect zero creep behavior or virgin curve slope. This characteristic was independent of experiments.
1982 a simple molecular statistical treatment for cholestericspmloscholte
1. The document presents a statistical mechanical treatment of a simplified molecular model for describing the cholesteric phase.
2. The model combines the Maier-Saupe interaction, which describes the nematic phase, with a twist interaction that induces helical twisting of the nematic director.
3. The model is solved using a mean field approximation, allowing analytical expressions to be obtained for relevant quantities like order parameters and free energy as a function of temperature.
1997 room temperature growth of submonolayers of silicon on si(001) studied w...pmloscholte
1) Room-temperature growth of submonolayers of silicon on Si(001) was studied using scanning tunneling microscopy (STM).
2) At low coverages, adatoms aggregate into dimers in different geometries (A, B, C, D). A kinetic model is proposed for dimer formation.
3) At higher coverages, dimers line up to form linear structures in the [110] and [310] directions. Near 0.2 ML coverage, these lines merge to form a random network that later converts into epitaxial dimer rows above 0.2 ML.
1998 characterisation of multilayers by x ray reflectionpmloscholte
This document presents a theoretical model for characterizing multilayers using X-ray reflection. The model includes refraction effects and describes diffuse scattering from multilayers with roughened interfaces, including islands and miscut-induced steps. The model calculates X-ray intensity profiles that can be compared to experimental data to deduce the morphology of interfaces, such as mean island size and average step height. The model is applied to experimental data from a Si/Ge multilayer and results in values consistent with AFM images.
1997 sodium doped dimer rows on si(001)pmloscholte
1) The stability and electronic structure of a sodium-doped silicon dimer row on the hydrogen-passivated Si(001) 2x1 surface is studied using first-principles calculations.
2) It is predicted that sodium atoms evaporated onto the surface will stick preferentially to the depassivated dimer row.
3) This leads to a partially filled empty one-dimensional state of the dimer row, making it metallic in character and behaving as a thin metallic nanowire of atomic dimensions.
1995 growth mechanisms of coevaporated sm ba2cu3oy thin filmspmloscholte
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
1996 atomic force microscopy study of (001) sr tio3 surfacespmloscholte
The document summarizes an atomic force microscopy study of SrTiO3 surfaces after different heat treatments. The key points are:
1) Annealing in O3 results in atomically flat terraces separated by smooth, one unit cell high steps that follow the substrate's miscut orientation.
2) Annealing in O2 produces irregularly shaped terraces with step heights varying between 0.5-2.5 unit cells. Line defects and holes are also observed.
3) Depositing SrTiO3 on a surface annealed in O3 increases roughness due to island formation but heals line defects.
4) Annealing in UHV produces rougher steps and surface clusters, indicating a
This document discusses approaches for improving nonuniformity correction (NUC) for resistive array infrared scene projectors. Current NUC schemes treat each pixel independently, but scene-based effects like power drops and thermal crosstalk across the array are important to consider. The document examines potential problems with scene-based correction and discusses algorithms that could be used, such as accounting for far-field diffraction effects between pixels. It also describes the current sparse array approach used to measure each pixel's response and derive nonuniformity correction curves.
This document provides an overview of Coherent X-ray Diffraction Imaging (CXDI) and its application to nanostructures. CXDI allows imaging of a sample without using lenses by measuring the diffraction pattern and reconstructing the image using iterative phase retrieval algorithms. The document discusses coherent scattering from finite size crystals, partially coherent illumination, and experimental examples of CXDI for studying crystalline structures at the nanoscale.
This document summarizes an experimental study that measured the saturation thickness of granite and glass materials using gamma backscattering. Gamma backscattering is a non-destructive testing technique that can determine material thickness and density by detecting gamma photons backscattered from within a material. The experiment used a 137Cs radioactive source and gamma spectroscopy system to measure the backscattered gamma photon count rates from granite and glass slabs of increasing thickness. The results were analyzed to estimate the saturation thickness for each material, above which increasing thickness does not significantly increase the backscattered count rate.
Image Quality, Artifacts and it's Remedies in CT-Avinesh ShresthaAvinesh Shrestha
CT is one of the frequently used diagnostic imaging modalities in Radiology. Knowledge about image quality and artifacts is essential when diagnosing a patient with the help of CT images. Moreover, Radiology Technologist's should be very well aware about the ways to identify and eliminate or minimize the artifacts in CT for better image quality.
Monte carlo Technique - An algorithm for Radiotherapy CalculationsSambasivaselli R
Monte Carlo techniques are used to simulate particle transport through complex geometries to calculate dose distributions. The key steps are: (1) sampling the distance to the next interaction, interaction type, and energy/direction of secondary particles, (2) tracking particle histories through condensed histories or splitting/Russian roulette, and (3) calculating dose deposition in voxels. While fully accurate, Monte Carlo is statistically limited by the number of histories. Variance reduction techniques increase efficiency but introduce weighting factors. Overall uncertainty is typically within 3% given proper commissioning and cross-section libraries.
EXPERIMENTAL RESEARCH OF HIGHLY RELIABLE METHODS OF HYDROACOUSTIC COMMUNICATI...sipij
This document summarizes experimental research on reliable hydroacoustic communication methods for confined bodies of water with low sound absorption and complex reverberation patterns. Experiments were conducted in a metal tank to test multi-frequency signals. Orthogonal frequency-division multiplexing signals modulated with pseudo-noise sequences were used. Time differences of arrival between transmitters were determined with an accuracy of a few samples by identifying the direct ray before the global maximum. Histograms of delays between direct and maximum rays showed distributions over limited ranges. The methods allowed reliable positioning with equipment using a 96 kHz sampling frequency in such confined long-reverberating environments.
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.
This document describes research on using near-infrared optical imaging techniques for 3D biological tissue imaging. It discusses diffuse optical tomography (DOT) and fluorescence DOT (F-DOT). For DOT, it covers the photon diffusion equation, forward and inverse models, and finite element method implementation. For F-DOT, it discusses the fluorescence transport equations and parallel inversion schemes. Simulation results using MATLAB and NIRFAST show reconstructed optical property maps and fluorescence distributions in 2D and 3D geometries. Future work aims to further develop 3D imaging software for interfacing with DOT instrumentation.
This document discusses factors that impact the image quality in CT scans. It describes key scanning parameters like milliampere, scan time, slice thickness, and reconstruction algorithm that determine image quality. Higher mA and shorter scan times improve image quality but increase radiation dose. Thinner slice thickness and smaller pixel size enhance spatial resolution. The modulation transfer function is used to evaluate a system's ability to resolve fine detail spatially. Selection of these parameters requires balancing optimal image quality with minimizing radiation dose to the patient.
1) The document discusses methods for improving the sensitivity of electronic support measure (ESM) receivers through post-integration processing using autocorrelation and cross-correlation.
2) Autocorrelation processing takes advantage of the periodic nature of radar signals to improve detection of high repetition frequency signals. It provides a sensitivity gain that depends on the integration window and pulse repetition interval.
3) Three estimators are examined for extracting radar parameters: a straightforward method, interpolation method, and maximum likelihood method, with the maximum likelihood method providing the best accuracy.
This document analyzes various wavelet transforms for edge detection in X-ray bone images. It begins with an introduction to edge detection and its importance in medical imaging. Classical derivative operators can detect edges but also extract false information and are sensitive to noise. Wavelet transforms offer multi-resolution analysis to detect edges at different scales. The document then provides background on wavelet theory and discrete wavelet transforms. It analyzes applying various orthogonal wavelets like Haar, Daubechies, and Coiflet to X-ray images and compares their performance in edge detection based on metrics like edge detection accuracy and computation time. Haar wavelets performed best at detecting edges with better quality in less time.
Applications for high speed Raman Microscopynweavers
The RAMAN-11 is a new generation of laser Raman microscope developed by Nanophoton that enables the fastest high definition Raman imaging. It combines laser microscope and Raman spectroscopy technologies. The RAMAN-11's imaging speed is 300-600 times faster than competitors and it opens up new applications. Its software supports rapid data acquisition and robust analysis functions.
Sub-windowed laser speckle image velocimetry by fast fourier transform technique
Abstract
In this work, laser speckle velocimetry, a unique optical method for velocity measurement of fluid flow has been described. A laser sheet is developed and is illuminated on microscopic seeded particles to produce the speckle pattern at the recording plane. Double frame- single-exposure speckle images are captured in such a way that the second speckle image is shifted exactly in a known direction. The auto-correlation method has the ambiguity of direction of flow. To rectify this, spatial shift of the second image has been premeditated. Cross-correlation of sub interrogation areas is obtained by Fast Fourier Transform technique. Four sub-windows processed to obtain the velocity information with vector map analysis precisely.
This document discusses and compares two techniques for image denoising using wavelet transforms: Dual-Tree Complex DWT and Double-Density Dual-Tree Complex DWT. Both techniques decompose an image corrupted by noise using filter banks, apply thresholding to the wavelet coefficients, and reconstruct the image. The Double-Density Dual-Tree Complex DWT yields better denoising results than the Dual-Tree Complex DWT as it produces more directional wavelets and is less sensitive to shifts and noise variance. Experimental results on test images demonstrate that the Double-Density method achieves higher peak signal-to-noise ratios, especially at higher noise levels.
1999 observation of zero creep in piezoelectric actuatorspmloscholte
The document summarizes experiments on piezoelectric actuators that observe zero creep in certain locations of the hysteresis loop. Specifically:
1) Relaxation experiments using an offset sinusoidal voltage found relaxation increased hysteresis loop tilt but did not reduce hysteresis. Zero creep was observed at hysteresis loop extremum.
2) Creep experiments varying delay time also increased loop tilt but zero creep locations did not change and coincided with points where loop slope equaled virgin curve slope.
3) Increasing input voltage amplitude did not affect zero creep behavior or virgin curve slope. This characteristic was independent of experiments.
1982 a simple molecular statistical treatment for cholestericspmloscholte
1. The document presents a statistical mechanical treatment of a simplified molecular model for describing the cholesteric phase.
2. The model combines the Maier-Saupe interaction, which describes the nematic phase, with a twist interaction that induces helical twisting of the nematic director.
3. The model is solved using a mean field approximation, allowing analytical expressions to be obtained for relevant quantities like order parameters and free energy as a function of temperature.
1997 room temperature growth of submonolayers of silicon on si(001) studied w...pmloscholte
1) Room-temperature growth of submonolayers of silicon on Si(001) was studied using scanning tunneling microscopy (STM).
2) At low coverages, adatoms aggregate into dimers in different geometries (A, B, C, D). A kinetic model is proposed for dimer formation.
3) At higher coverages, dimers line up to form linear structures in the [110] and [310] directions. Near 0.2 ML coverage, these lines merge to form a random network that later converts into epitaxial dimer rows above 0.2 ML.
1998 characterisation of multilayers by x ray reflectionpmloscholte
This document presents a theoretical model for characterizing multilayers using X-ray reflection. The model includes refraction effects and describes diffuse scattering from multilayers with roughened interfaces, including islands and miscut-induced steps. The model calculates X-ray intensity profiles that can be compared to experimental data to deduce the morphology of interfaces, such as mean island size and average step height. The model is applied to experimental data from a Si/Ge multilayer and results in values consistent with AFM images.
1997 sodium doped dimer rows on si(001)pmloscholte
1) The stability and electronic structure of a sodium-doped silicon dimer row on the hydrogen-passivated Si(001) 2x1 surface is studied using first-principles calculations.
2) It is predicted that sodium atoms evaporated onto the surface will stick preferentially to the depassivated dimer row.
3) This leads to a partially filled empty one-dimensional state of the dimer row, making it metallic in character and behaving as a thin metallic nanowire of atomic dimensions.
1995 growth mechanisms of coevaporated sm ba2cu3oy thin filmspmloscholte
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
1996 atomic force microscopy study of (001) sr tio3 surfacespmloscholte
The document summarizes an atomic force microscopy study of SrTiO3 surfaces after different heat treatments. The key points are:
1) Annealing in O3 results in atomically flat terraces separated by smooth, one unit cell high steps that follow the substrate's miscut orientation.
2) Annealing in O2 produces irregularly shaped terraces with step heights varying between 0.5-2.5 unit cells. Line defects and holes are also observed.
3) Depositing SrTiO3 on a surface annealed in O3 increases roughness due to island formation but heals line defects.
4) Annealing in UHV produces rougher steps and surface clusters, indicating a
1986 the influence of conduction electrons on the efg of amorphous intermetal...pmloscholte
This document discusses the influence of conduction electrons on the electric field gradient (EFG) in amorphous intermetallic alloys. It presents a model that incorporates a screening term for the electronic contribution to the EFG using Thomas-Fermi screening. Mossbauer spectroscopy experiments were conducted on amorphous FeZr and (FeCu)Zr alloy ribbons and films prepared by meltspinning and coevaporation. The results show that screening must be considered to understand the quadrupole splitting observed in alloys where the density of states at the Fermi level varies with concentration.
2001 field based scanning tunneling microscope manipulation of antimony dimer...pmloscholte
This summary provides the key details from the document in 3 sentences:
The document discusses an experiment that investigated manipulating antimony dimers (Sb2) on the silicon (001) surface using a scanning tunneling microscope (STM). Directed movement of Sb2 dimers was achieved through an asymmetric scanning technique of the STM tip, where parameters were varied between left-to-right and right-to-left scanning to create a preferential direction for the dimers to move. While the yield for directed manipulation was low, statistics on enhanced hopping rates of Sb2 dimers are reported and models involving an induced dipole interaction between the tip and dimer are discussed as explanations for the observed behavior.
1995 analysis of piezo actuators in translation constructionspmloscholte
1) A translation stage using piezo stacks as actuators was developed to generate displacements with nanometer accuracy over a dynamic range of 10 micrometers. Capacitive sensors were able to measure displacements with subnanometer resolution.
2) Using the high precision measurements from the capacitive sensors, the displacement properties of the piezo actuator in the translation stage could be characterized with great accuracy when different voltages were applied.
3) A model is presented to describe the general behavior of a piezo actuator in a translation stage, and the hysteresis behavior observed in the piezo actuator is found to have point symmetry properties and branches that can be described by third-order polynomials.
1996 strain in nanoscale germanium hut clusters on si(001) studied by x ray d...pmloscholte
This document summarizes a study that used x-ray diffraction and scanning tunneling microscopy to investigate the strain in nanoscale germanium hut clusters on silicon substrates. The key findings are:
1) X-ray diffraction measurements revealed contributions from the hut clusters that allowed determining the strain distribution uniquely from the clusters.
2) The germanium clusters are almost fully strained with 0.5% misfit at the interface but strain is relaxed towards the apex, with 4.2% misfit indicating the natural germanium lattice spacing.
3) By modeling the asymmetric intensity distributions around diffraction peaks, the study determined that strain is relaxed uniformly through the hut clusters from a maximum near the interface to a minimum
1998 epitaxial clusters studied by synchrotron x ray diffraction and scanning...pmloscholte
1) The document summarizes studies of three nanoscale cluster systems using synchrotron X-ray diffraction and scanning tunneling microscopy: Ge hut clusters on Si(001), In clusters on Ge(001) that form 103 facets, and wedge-shaped Cu clusters buried in Cu films on Ni(001).
2) X-ray diffraction is used to determine the fundamental structural properties of the clusters, such as strain relaxation, by measuring crystal truncation rods from the cluster facet planes.
3) For the Ge/Si system, diffraction data found strain relaxation of 0.5-4% within the hut clusters. For the In/Ge system, clusters were completely relaxed from the substrate with In atoms stabilizing the
1989 optical measurement of the refractive index, layer thickness, and volume...pmloscholte
This document discusses a method for determining the complex refractive index, layer thickness, and volume changes of thin films using optical measurements. The method involves measuring reflectance and transmittance values across a range of intentionally varied layer thicknesses, rather than fitting those values as functions of independently measured thicknesses. The measurements provide information needed for optical recording applications. The complex refractive index, layer thicknesses, and volume changes can then be unambiguously calculated by fitting curves to the reflectance-transmittance plane measured across multiple thicknesses. An example application determines these properties for thin films of GaSb and InSb for use in optical recording.
1998 growth pyramids on si(111) facets a cvd and mbe studypmloscholte
1) The morphology of growth pyramids formed on Si(111) facets during CVD growth was studied using atomic force microscopy.
2) Spiral and concentric step edge patterns were observed on the pyramid tops, indicating the pyramids originated from different types of dislocations.
3) The step edge patterns and sharp corners suggest growth during CVD is governed by step edge processes and surface diffusion is not rate limiting.
1996 interactions between adsorbed si dimers on si(001)pmloscholte
1) The interactions between adsorbed silicon dimers on a silicon 001 surface were studied using scanning tunneling microscopy.
2) It was found that by increasing the tip-sample voltage, transitions between clusters of dimers could be induced. These field-enhanced transitions allowed the interactions between dimers to be clarified.
3) Two dimers in a BB configuration were found to interact strongly, forming a faintly visible "twin" structure. In contrast, dimers in an AB configuration showed little interaction.
1992 asymmetrical dimers on the ge(001) 2 × 1-sb surface observed using x-ray...pmloscholte
The document summarizes a study that used x-ray diffraction to determine the atomic structure of the 2x1 reconstruction on the Ge(001) surface induced by antimony (Sb) adsorption. The key findings are:
1) Sb forms asymmetric dimers on the Ge(001) surface, replacing the symmetric Ge dimers, with a bond length of 2.90 Angstroms and a midpoint shift of 0.16 Angstroms.
2) This is the first reported asymmetric dimer structure for a group IV/V system, in contrast to the symmetric dimers typically observed for systems like As/Si(001).
3) Relaxations of the top four substrate layers were also measured and compared
1996 new application of classical x ray diffraction methods for epitaxial fil...pmloscholte
This document describes a new method for using classical X-ray diffraction to characterize epitaxial thin films. The method combines powder diffraction data with a Weissenberg camera technique to provide a complete overview of the in-plane and out-of-plane characteristics of the film and its relationship to the substrate in just two scans. This includes information on the film's orientation, strain, texture, and lattice parameters relative to the substrate. The method is illustrated using several epitaxial film/substrate systems and provides structural information simply and reliably using standard laboratory X-ray equipment.
Investigation of repeated blasts at Aitik mine using waveform cross correlationIvan Kitov
We present results of signal detection from repeated events at the Aitik and Kiruna mines in Sweden as based on waveform cross correlation. Several advanced methods based on tensor Singular Value Decomposition is applied to waveforms measured at seismic array ARCES, which consists of three-component sensors.
Microwave Planar Sensor for Determination of the Permittivity of Dielectric M...journalBEEI
This paper proposed a single port rectangular microwave resonator sensor. This sensor operates at the resonance frequency of 4GHz. The sensor consists of micro-strip transmission line and applied the enhancement method. The enhancement method is able to improve the return loss of the sensor, respectively. Plus, the proposed sensor is designed and fabricated on Roger 5880 substrate. Based on the results, the percentage of error for the proposed rectangular sensor is 0.2% to 8%. The Q-factor of the sensor is 174.
Projected Barzilai-Borwein Methods Applied to Distributed Compressive Spectru...Polytechnique Montreal
Cognitive radio allows unlicensed (cognitive) users to use licensed frequency bands by exploiting spectrum sensing techniques to detect whether or not the licensed (primary) users are present. In this paper, we present a compressed sensing applied to spectrum-occupancy detection in wide-band applications. The collected analog signals from each cognitive radio (CR) receiver at a fusion center are transformed to discrete-time signals by using analog-to-information converter (AIC) and then employed to calculate the autocorrelation. For signal reconstruction, we exploit a novel approach to solve the optimization problem consisting of minimizing both a quadratic (l2) error term and an l1-regularization term. In specific, we propose the Basic gradient projection (GP) and projected Barzilai-Borwein (PBB) algorithm to offer a better performance in terms of the mean squared error of the power spectrum density estimate and the detection probability of licensed signal occupancy.
Abstract
Terahertz sub-surface imaging offers an effective solution for surface and 3D imaging because of minimal
sample preparation requirements and its ability to “see” below the surface. Another important property is the ability
to inspect on a layer-by layer basis via a non-contact route, non-destructive route. Terahertz 3D imager designed
at Applied Research and Photonics (Harrisburg, PA) has been used to demonstrate reconstructive imaging with a
resolution of less than a nanometer. Gridding with inverse distance to power equations has been described for 3D
image formation. A continuous wave terahertz source derived from dendrimer dipole excitation has been used for
reflection mode scanning in the three orthogonal directions. Both 2D and 3D images are generated for the analysis
of silver iodide quantum dots’ size parameter. Layer by layer image analysis has been outlined. Graphical analysis
was used for particle size and layer thickness determinations. The demonstrated results of quantum dot particle
size checks well with those determined by TEM micrograph and powder X-ray diffraction analysis. The reported
non-contact measurement system is expected to be useful for characterizing 2D and 3D naomaterials as well as for process development and/or quality inspection at the production line.
This document proposes a holistic approach to reconstruct data in ocean sensor networks using compression sensing. It involves two key aspects:
1) A node reordering scheme is developed to improve the sparsity of signals in the discrete cosine transform or Fourier transform domain, reducing the number of measurements needed for accurate reconstruction.
2) An improved sparse adaptive tracking algorithm is adopted to estimate the sparse degree and then reconstruct the signal in a step-by-step manner, gradually converging on an accurate reconstruction even with unknown sparsity.
Simulation results show the proposed method can effectively reduce signal sparsity and accurately reconstruct signals, especially in cases of unknown sparsity.
The document presents two oscillation control algorithms for resonant sensors like vibratory gyroscopes. The first algorithm uses automatic gain control and a phase-locked loop to track the resonant frequency while maintaining a specified amplitude. The second algorithm tunes the resonant frequency to a specified value by modifying the resonator dynamics, while also using automatic gain control to regulate the amplitude. Both control systems are analyzed for stability using an averaging method. The algorithms are applied to problems in dual-mass vibratory gyroscopes and general vibratory gyroscopes to demonstrate their effectiveness.
Computed tomography (CT) provides cross-sectional images of the body using X-rays. CT has evolved through several generations with advances in technology. Modern multi-detector CT allows acquisition of multiple slices simultaneously, reducing scan time. Helical or spiral CT involves continuous table movement and X-ray rotation, allowing whole organ or body coverage with minimal artifacts. Pitch relates the table speed to beam width and affects radiation dose and anatomic coverage. CT has advantages over conventional radiography including better contrast resolution and ability to distinguish between tissues.
Computed tomography (CT) uses rotating X-rays and computer processing to create cross-sectional images of the body. CT provides advantages over conventional radiography like distinguishing between tissues with similar densities and detecting differences as small as 0.5% contrast. Modern CT systems use multiple detector rows to acquire multiple slices simultaneously during each rotation, improving coverage and reducing scan time. Advanced techniques like multiplanar reformation and 3D rendering provide additional diagnostic information from CT images. Artifacts can arise from factors like the helical acquisition and differences between detector rows.
Spatially adiabatic frequency conversion in opto-electro-mechanical arraysOndrej Cernotik
Optoelectromechanical systems offer a promising route towards frequency conversion between microwaves and light and towards building quantum networks of superconducting circuits. Current theoretical and experimental efforts focus on approaches based on either optomechanically induced transparency or adiabatic passage. The former has the advantage of working with time-independent control but only in a limited bandwidth (typically much smaller than the cavity linewidth); the latter can, in principle, be used to increase the bandwidth but at the expense of working with time-dependent control fields and with strong optomechanical coupling. In my presentation, I will show that an array of optoelectromechanical transducers can overcome this limitation and reach a bandwidth that is larger than the cavity linewidth. The coupling rates are varied in space throughout the array so that a mechanically dark mode of the propagating fields adiabatically changes from microwave to optical or vice versa. This strategy also leads to significantly reduced thermal noise with the collective optomechanical cooperativity being the relevant figure of merit. I will also demonstrate that, remarkably, the bandwidth enhancement per transducer element is largest for small arrays. With these features the scheme is particularly relevant for improving the conversion bandwidth in state-of-the-art experimental setups.
Complimentary split ring resonator sensor with high sensitivity based on mate...TELKOMNIKA JOURNAL
A new model of microwave planar sensor established on the complementary split ring resonator (CSRR) as well as an air hole in substrate of the structure is introduced for a precise measurement of materials permittivity. The hole is filled into substrate of the planar microstrip line. The CSRR structure with hole is selected for the sensitivity analysis, the result is established to hold over quite sensitive compared with CSRR structure without hole and thus evidence to be more suitable for the sensor design. The sensor in the form of CSRRs operating at a 1.74–3.4 GHz band is explained. At resonance, it is found that the electric field produced straight the plane of CSRR being highly sensitive for the characterization of sample resident with the sensor. The minimum transmission frequency of sensor shifts from 3.4 to 1.74 GHz as the sample permittivity varies from 1 to 10. A numerical paradigm is introduced herein for the computation of the system resolution as a assignment of resonance frequency and sample permittivity using electromagnetic simulator. It is found that the proposed sensor provides 35% increment in sensitivity more than conventional sensor for same permittivity of the specimen.
IRJET- Compressed Sensing based Modified Orthogonal Matching Pursuit in DTTV ...IRJET Journal
This document discusses a modified orthogonal matching pursuit algorithm used for channel estimation in digital terrestrial television systems. It proposes using compressed sensing based channel estimation at the receiver to eliminate sparse information. Thresholding is used to remove noise from the channel estimation and improve signal quality. Simulation results show that bit error rate decreases when the received signal power from different transmitters is almost equal.
Aggelos Katsaggelos, Professor and AT&T Chair, Northwestern University, Department of Electrical Engineering & Computer Science (IEEE/ SPIE Fellow, IEEE SPS DL), Sparse and Redundant Representations: Theory and Applications
Analysis Of High Resolution FTIR Spectra From Synchrotron Sources Using Evolu...Heather Strinden
This document discusses the analysis of a high resolution FTIR spectrum of trimethylene sulfide (TMS) using evolutionary algorithms (EA). The spectrum was collected at the Canadian Light Source with a resolution of 0.00096 cm-1. Preliminary analysis using traditional methods assigned 2358 transitions. EA was also applied and yielded spectroscopic constants that similarly reproduced the complex experimental spectrum. As a test, EA was also successfully applied to a previously analyzed spectrum of azetidine, demonstrating the robustness of the EA method for automated assignment of dense rovibrational spectra.
Qualitative analysis of Fruits and Vegetables using Earth’s Field Nuclear Mag...IJERA Editor
Among the imaging techniques, magnetic resonance imaging (MRI) is a non-contact and a non-invasive technique to obtain images of the objects rich in water content and provides an excellent tool to study variation of contrast among the soft issues. It often utilizes a linear magnetic field gradient to obtain an image that combines the visualization of molecular structure and dynamics. It measures the characteristics of hydrogen nuclei of water and nuclei with similar chemical shifts, modified by chemical environment across the object. In the present work, MRI of fresh tomatoes has been recorded using Terranova-MRI for qualitative analysis. The technique is effective, powerful and reliable as an investigative tool in the quality analysis and diagnosis of infections in fruits and vegetables.
This paper presents an approach for image restoration in the presence of blur and noise. The image is divided into independent regions modeled with a Gaussian prior. Wavelet based methods are used for image denoising, while classical Wiener filtering is used for deblurring. The algorithm finds the maximum a posteriori estimate at the intersection of convex sets generated by Wiener filtering. It provides efficient image restoration without sacrificing the simplicity of filtering, and generates a better restored image.
Basic physics of multidetector computed tomography ( CT Scan) - how ct scan works, different generations of ct, how image is generated and displayed and image artifacts related to CT Scan.
Identification of the Memory Process in the Irregularly Sampled Discrete Time...idescitation
This poster paper analyzes the memory process in the irregularly sampled daily solar radio flux signal between 1972-2013. The authors apply Savitzky-Golay filtering to denoise the signal, then use Finite Variance Scaling Method and Hurst exponent analysis to investigate the memory pattern. Their analysis finds the signal exhibits short memory behavior, suggesting it may have multi-periodic or pseudo-periodic characteristics. This provides insight into the internal dynamics and particle acceleration processes of the Sun.
1. MRI magnets have advanced to routinely use 3T systems for clinical use and up to 17T for research use. Higher field strengths provide improved image quality but also introduce disadvantages like increased chemical shift effects.
2. Gradients and RF coils have also advanced, allowing for faster imaging sequences through increased amplitude/rise time of gradients and use of parallel imaging from multiple coil elements.
3. Echo planar imaging is a fast MRI technique that acquires a whole image within a fraction of a second, enabling imaging of rapid physiological processes. It is used for diffusion weighted imaging, perfusion imaging, and functional MRI.
The document describes a new broadband permeameter technique for measuring the complex permeability and permittivity of rectangular magnetic samples in-situ from 130 MHz to 7 GHz. The technique uses S-parameter measurements of an asymmetrical stripline containing the sample under test, and employs an optimization method to extract the electromagnetic properties of the sample by matching theoretical and measured effective parameters. Experimental results are presented to validate the quasistatic electromagnetic analysis approach used in the permeameter.
Similar to 1998 Appl. Phys. A 66 (1998), p857 design and construction of a high resolution 3 d translation stage for metrological applications (20)
1996 a calibrated scanning tunneling microscope equipped with capacitive sensorspmloscholte
1) A scanning tunneling microscope equipped with capacitive sensors has been developed to measure the real-time X-Y position and correct for errors caused by piezoelectric actuator properties like hysteresis and nonlinearity.
2) The microscope uses a calibrated scanning stage with capacitive sensors that measure the actual X-Y position and provide feedback to dynamically adjust the piezo voltages to reach the desired scanning positions with minimal error.
3) This allows surfaces to be scanned geometrically accurately while correcting for drift and low-frequency vibrations in real time.
1994 restoration of noisy scanning tunneling microscope imagespmloscholte
This document compares and improves several implementations of the Wiener filter to remove noise from Scanning Tunneling Microscope (STM) images. It finds that the implementation by Weisman et al. using the noise model of Stoll et al. provides the best performance on both simulated and real STM images. It tests the filters on simulated graphite images with added 1/f noise and finds the modified Weisman filter performs significantly better than other implementations on a real STM graphite image due to deviations from the 1/f noise model.
2000 surface polymerization of epitaxial sb wires on si(001)pmloscholte
This document reports on a study of the local density of states of epitaxial antimony nanostructures on silicon 001 using scanning tunneling spectroscopy. The key findings are:
1) Epitaxial antimony lines self-assemble on the silicon surface when antimony is deposited at low rates and the sample is annealed. The lines are two atoms wide and extend up to 12 antimony dimers in length.
2) Spectroscopy shows the electronic structure in the center of the antimony lines is similar to the silicon surface, indicating the lines are nonmetallic. In contrast, the ends of the lines show a finite density of states at the Fermi level, consistent with theoretical predictions of a "radical
1998 epitaxial film growth of the charge density-wave conductor rb0.30 moo3 o...pmloscholte
1) Thin films of the charge density wave compound Rb0.30MoO3 were grown on SrTiO3 (001) substrates using pulsed laser deposition.
2) Initial growth proceeds through the formation of uniform, droplet-shaped islands that are fully relaxed. Thicker films form larger clusters that differ in size and have asymmetric shapes with clear facets.
3) X-ray diffraction shows the films have a preferred out-of-plane growth direction and four in-plane orientations corresponding to the symmetry of the SrTiO3 substrate. The correlation length perpendicular to the charge density wave axis is smaller than the dimensions of the grain clusters in thicker films.
1997 nucleation of homoepitaxial si chains on si(001) at room temperaturepmloscholte
1) Si dimers initially adsorb at preferred sites on the Si(001) surface, with most occupying C-positions.
2) Interactions between dimers and diffusing adatoms lead to the formation of three-atom clusters like twins and crosses. These can extend into diluted lines of C dimers along [110] and [310] directions.
3) Upon further deposition, the diluted dimer lines transform into epitaxial dimer rows through a process starting at the line ends of reorienting dimers and adding mobile adatoms.
1997 atomic details of step flow growth on si(001)pmloscholte
1. The study uses scanning tunneling microscopy to observe atomic details of step flow growth on the Si(001) surface at the single adatom level.
2. Empty state images clearly show single adatoms bound to step edges, revealing stable binding sites. Subsequent addition of adatoms forms different step edge configurations.
3. Dynamic processes are also observed, including adatom diffusion along step edges between stable binding sites and dimer formation between two adatoms.
4. Different step edge configurations are stable and can serve as sites for other processes, such as creating single dimer vacancies, providing insight into growth mechanisms.
1996 origin of rippled structures formed during growth of si on si(001) with mbepmloscholte
The document summarizes research into the origin of rippled structures that form on the surface of silicon during molecular beam epitaxy growth on Si(001) substrates. Through experiments using x-ray crystallography, optical microscopy, and atomic force microscopy, the researchers found that the rippled structure is caused by correlated kink bunching along step edges, rather than by step bunching. They present a model wherein the inherent discreteness of growth can cause deviations from the equilibrium kink distribution large enough to induce step-step interactions and the formation of ripples.
1995 mechanism of the step flow to island growth transition during mbe on si(...pmloscholte
The document discusses the transition between step flow and island growth during molecular beam epitaxy of silicon on a silicon (001) surface with dimer rows. It finds that:
1) For typical experimental conditions, diffusion perpendicular to the dimer rows cannot be neglected and a transition occurs from effectively 1D to 2D diffusion as the terrace width increases.
2) When including 2D diffusion, the critical flux for the step flow to island growth transition scales as the terrace width to the -4th power for large terraces, but as the terrace width to the -3rd power for small terraces.
3) Comparing to experimental data, accounting for diffusion perpendicular to the dimer rows is essential
1994 the influence of dimerization on the stability of ge hutclusters on si(001)pmloscholte
1) The epitaxial growth of Ge on Si(001) initially proceeds two-dimensionally but then forms three-dimensional Ge nanocrystals called "hutclusters".
2) Hutclusters have well-defined, highly anisotropic shapes bounded by (105) facets, which is surprising since (105) facets are normally not stable for macroscopic crystals.
3) The paper presents a model to explain the stability and morphology of hutclusters, identifying the key parameters of strain from lattice mismatch, nanocrystal size, and surface energies of the substrate and nanocrystal facets.
1994 nucleation and growth of c parallel grains in co-evaporated sm ba2cu3oy ...pmloscholte
1) The study investigates the nucleation and growth of c-parallel (c//) grains in co-evaporated SmBa2Cu3Oy films using scanning tunneling microscopy, x-ray diffraction, and transmission electron microscopy.
2) It was found that the volume fraction of c// grains increases with increasing supersaturation during film growth, indicating that kinetic factors like reduced surface mobility promote c// nucleation over c-perpendicular growth.
3) No evidence was found of a critical thickness for a switch from c-perpendicular to c// growth; instead, c// grains nucleate throughout film growth when supersaturation is high.
1994 atomic structure of longitudinal sections of a pitch based carbon fiber ...pmloscholte
1) STM images of longitudinal sections of pitch-based carbon fibers revealed a hexagonal superstructure with a periodicity of 14.9 A, indicating the top graphitic plane was rotated 9.5" from the underlying bulk.
2) Near defects, this superstructure was modulated with a (6 x fi)R30" pattern. The same modulation was found in images showing atomic resolution.
3) Power spectra of modulated regions contained extra peaks corresponding to the (6 x fi)R30" pattern, in addition to the six peaks from the hexagonal graphitic structure. This indicates the atomic structure is disturbed to a depth of at least two layers from the surface.
1992 schottky barrier formation in conducting polymerspmloscholte
1. The authors studied thin films of poly(3-hexylthiophene) (PHT) and polypyrrole (PPY) on highly oriented pyrolytic graphite using scanning tunneling microscopy.
2. They observed semicrystalline order in the form of micro-islands connected by parallel polymer strands. The orientation of the strands is determined by the substrate.
3. For PPY films, they observed superhelical structures not previously reported. The apparent height of polymer strands was found to differ for positive and negative bias voltages, which the authors attribute to the formation of a Schottky barrier between the metallic tip and semiconducting polymer.
1990 crystallization kinetics of thin amorphous in sb filmspmloscholte
1) Evaporated and sputtered InSb films have different crystallization properties. Evaporated films have a lower activation energy of 1.39 eV and crystallize by three-dimensional growth on existing nuclei.
2) Sputtered films have a higher activation energy of 2.7 eV and crystallize by nucleation and subsequent growth on the nuclei. The Avrami exponent indicates sputtered films require crystalline nuclei to form before crystallization can begin.
3) Transmission electron microscopy images show evaporated films have existing nuclei while sputtered films have no visible crystallites in the as-deposited state, requiring nucleation.
1988 a study of the thermal switching behavior in gd tbfe magneto‐optic films...pmloscholte
1) A study examined the thermal switching behavior of GdTbFe magneto-optic films using two laser beams - a krypton laser (753 nm) to locally heat spots and a semiconductor laser (820 nm) to monitor changes in magnetization.
2) It was observed that magnetization reversal within the heated spots was delayed after the start of heating, with delay times ranging from 200 microseconds to 2 seconds depending on factors like applied field and heating power.
3) Analysis indicated the delayed switching was partly due to the time needed to reach the temperature required for reversal as the spot heated up, though other magnetic processes may also have contributed to the delay.
A Visual Guide to 1 Samuel | A Tale of Two HeartsSteve Thomason
These slides walk through the story of 1 Samuel. Samuel is the last judge of Israel. The people reject God and want a king. Saul is anointed as the first king, but he is not a good king. David, the shepherd boy is anointed and Saul is envious of him. David shows honor while Saul continues to self destruct.
How Barcodes Can Be Leveraged Within Odoo 17Celine George
In this presentation, we will explore how barcodes can be leveraged within Odoo 17 to streamline our manufacturing processes. We will cover the configuration steps, how to utilize barcodes in different manufacturing scenarios, and the overall benefits of implementing this technology.
Level 3 NCEA - NZ: A Nation In the Making 1872 - 1900 SML.pptHenry Hollis
The History of NZ 1870-1900.
Making of a Nation.
From the NZ Wars to Liberals,
Richard Seddon, George Grey,
Social Laboratory, New Zealand,
Confiscations, Kotahitanga, Kingitanga, Parliament, Suffrage, Repudiation, Economic Change, Agriculture, Gold Mining, Timber, Flax, Sheep, Dairying,
This presentation was provided by Racquel Jemison, Ph.D., Christina MacLaughlin, Ph.D., and Paulomi Majumder. Ph.D., all of the American Chemical Society, for the second session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session Two: 'Expanding Pathways to Publishing Careers,' was held June 13, 2024.
A Free 200-Page eBook ~ Brain and Mind Exercise.pptxOH TEIK BIN
(A Free eBook comprising 3 Sets of Presentation of a selection of Puzzles, Brain Teasers and Thinking Problems to exercise both the mind and the Right and Left Brain. To help keep the mind and brain fit and healthy. Good for both the young and old alike.
Answers are given for all the puzzles and problems.)
With Metta,
Bro. Oh Teik Bin 🙏🤓🤔🥰
2. S858
Given that the novel STM is intended for use in metrology
and atomic manipulation, the resolution and accuracy should
be well below the dimensions of a typical atomic radius. We
have therefore set the required resolution in the lateral direc-
tions (x, y) to 30 pm and the resolution in the perpendicular
direction (z) to 10 pm. The total scanning volume was taken 10 cm
as 50 µm × 50 µm × 10 µm (x × y × z) resulting in a dynamic
range of about 6 orders of magnitude, or 21 bits, in each
direction.
2 The capacitive translation sensor Fig. 2. The electrode patterns of the 3D translation sensor
In Fig. 1 a basic capacitive lateral translation sensor is
schematically displayed. The upper electrodes 1 and 2 are in (2), the equation for the z configuration (the plane parallel
driven with equal AC voltages of opposite phase. When the capacitor) is obtained. From this equation the desired reso-
upper plate is positioned symmetrically over the lower elec- lution of 10 pm in the z direction yields a minimum total area
trode 3, the capacitively induced currents will cancel out. for the z electrode of 3.5 cm2 . Given the minimum total areas
When one of the plates is translated in the x direction the can- for the lateral and the z detection the overall lateral dimen-
cellation will no longer be complete and a net current will sions of the sensor become 10 cm × 10 cm. Because accurate
flow through the capacitor. Analysis reveals that fringing ef- alignment of the sensor plates with respect to each other and
fects at the edges of the electrodes can be neglected if the with respect to the translation stage is crucial for optimum
design rules [3] are adhered to. Consequently the relation be- performance, the electrode structures have been split into sev-
tween the change in capacitance ∆C and the translation ∆x is eral sub-structures. Depending on the combination of elec-
expressed by [3] trodes and the phase of the electrode signals, measurements in
all six degrees of freedom can be performed [4].
2εoεr ∆xL
∆C = (2)
d
2.1 Modulo measurement technique
In other words, the change in capacitance ∆C is linear in the
translation ∆x and inversely proportional to the plate separa-
Although the capacitive sensor itself is designed to provide
tion d. The resolution is determined by the smallest detectable
the required resolution over the full dynamic range, the sig-
change in capacitance and is therefore linked to the total elec-
nal conditioning electronics (i.e. phase-sensitive detectors)
trode area and the plate separation. Out of this basic concept
have a more limited dynamic range. The full scanning vol-
a capacitive 3D translation sensor has been developed [4].
ume of the translation stage of 50 µm × 50 µm × 10 µm is
Given the fact that a change ∆C in capacitance down to
therefore mapped onto several regions of measurement. An
10−18 F can be measured, the required change in electrode
auxiliary capacitor bank is used for each direction to provide
area ∆A for a translation ∆x of 30 pm is given by
so-called compensating capacitors that are switched parallel
∆A ∆Cd and in anti-phase with the sensor capacitors. The individual
=L≥ (3) capacitance values of the compensator range from a unit value
∆x 2εo εr ∆x
C to 210 × C. The binary code that is used to select the ap-
The required length L of the electrode for a sensor plate sep- propriate value for the compensating capacitance is a direct
aration d = 200 µm is therefore at least 38 cm. In order to representation of the 10 least significant bits (lsb) of the probe
keep the dimensions of the sensor within acceptable limits position. With this strategy a modulo type measurement is re-
the electrodes for the detection of the lateral translations have alized to exploit the full potential of the capacitive sensors
been shaped in the folded configuration shown in Fig. 2. The and to obtain the required resolution and range at the expense
electrodes for the detection of the z translation are situated of using an extra capacitor array.
between the electrodes for the detection of the lateral transla-
tion. In contrast to the lateral detection, the z capacitors detect
the change in the plate separation. By ignoring the factor 2 3 The translation stage
The translation stage is configured as a flexure because of the
excellent mechanical properties for small range translations.
The outer dimensions of the STM stage are mainly deter-
1 2
L mined by the size of the capacitive sensor and the size of the
piezo stacks. In Fig. 3 the lower section of the stage is shown
in detail. Spring-loaded piezo stacks are used to drive the cen-
d
3
tre section of the stage in both lateral directions (x, y) via
a lever mechanism. The lever mechanism is primarily used
to decouple the x and y piezos and to minimize shear forces.
D x Due to the placement of the flexures at the corners of the cen-
Fig. 1. A basic capacitive translation sensor tre section the strain is confined to small areas in these regions
3. S859
transfer function of this controller is equal to
z+1
K(z) = k I (4)
z−1
When a square wave voltage is applied to the x-piezo, the cor-
responding position changes are not instantaneous, as shown
in Fig. 4. In other words, the open loop system requires a cer-
Z Y tain amount of time to reach, in an oscillatory pattern, the
Z stage
Long range change in position corresponding to the altered applied volt-
piezo stack age. Similar tests show that the response of the stage to a si-
X Sensor plates nusoidal voltage signal is periodic but not perfectly sinusoidal
Primary signal (Fig. 5). Consequently, when the position signal is displayed
conditioning against the voltage signal, a cigar-shaped hysteresis loop re-
Fig. 3. A schematic view of the lower section of the STM translation stage. sults (Fig. 6). With feedback controller (4) we can not only
The second electrode plate (not shown) is positioned just above the one reduce the settling time of the position signal but also re-
mounted in the lower section duce its oscillatory behavior (Fig. 7). The traces represent
different settings of the controller K(z); k I = 500, 2000 re-
spectively. Furthermore, for k I = 2000, an accurate response
so distortion of the capacitive sensor plate (which forms one of the stage can be created as shown by the second trace
part of the position sensor) is minimized. Although the capac- in Fig. 6, where the desired position signal is depicted against
itive sensor described previously is capable of measuring x, y the actual position measurements. The fact that the width of
and z translations, the construction of the stage allows for lat- the loop is small indicates that the desired and actual re-
eral displacements of the central area only. Therefore, in this sponses are nearly identical.
application, a separate z stage with a small capacitive sensor Additional testing of PID-type feedback controllers re-
is used and is located at the mechanical and thermal centre of vealed a limited application area for each parameter setting.
the stage. Almost every change in scanning parameters and/or change in
sample required a retuning of the controller. A model-based
position feedback controller is much more flexible and of-
fers improved overall performance. However, for the design
4 Modelling and control of such a controller, a dynamic model of the translation stage
is required.
Availability of the position measurements offers the opportu- Theoretical considerations as well as experimental re-
nity to use position feedback control as a means of improving sults suggest that PEAs exhibit dynamic behavior [5]. Con-
the quantitative abilities of the microscope. In order to as- sequently, it is not permissible to partition the overall dy-
sess the effects of position feedback control, we implemented namic model into a purely dynamic component and a purely
a digital PI(D) type controller [2] on a prototype translation
stage with an integrated 2D sensing system [1]. The z-domain
1.5
2.5
1
2
1.5 0.5
Position voltage [V]
response
Position voltage [V]
1
0
0.5
stimulus
-0.5
0
-0.5
-1
-1
-1.5
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
-1.5
0.1 0.105 0.11 0.115 0.12 0.125 0.13
Time [s]
Time [s]
Fig. 5. Response of the stage to a sinusoidal stimulus without feedback
Fig. 4. Transient response of the stage without feedback control control
4. S860
1.5
arable, as well as the fact that the overall system must be
amenable to control technology, a model for the system dy-
namics is needed in the form of a cascade combination of
1
a linear dynamic model and a dynamic hysteresis operator.
Although the STM controller will be designed for overall
control of the microscope, it should also be able to oper-
Acquired position [V]
0.5
ate alongside existing STM hardware and software. Given
the operational specifications, the DSP system must have
a resolution of 21 bits or more. However, conversion mod-
0
ules compliant with such stringent specifications have traded
resolution for speed. Fortunately, we do not need a 21-bit A/D
open-loop conversion system because of the 10-lsb position measure-
-0.5 response
ment provided by the modulo measurement technique. Fur-
thermore, once 21-bit position measurements are available, an
effective 21-bit actuation capability can be created through
-1
the use of parallel D/A channels of lower resolution.
Operational considerations favor the introduction of pri-
mary and secondary positioning phases. In the primary posi-
-1.5
-1.5 -1 -0.5 0 0.5 1 tioning phase, the tip is brought into the starting position for
the scan. With respect to this phase, accuracy is paramount in
Desired position [V] comparison to speed. Execution of a scan relative to the start-
Fig. 6. Open- and closed-loop response of the stage ing position is the task of the secondary positioning phase.
Accuracy and speed are now equally important, implying that
modulo measurement (i.e. capacitor switching) is unaccept-
1.5 able. For the purpose of maximizing operating flexibility, the
kI = 2000 DSP system will be such that both the primary and the sec-
ondary positioning phases can rely on independent A/D and
1 D/A channels.
Finally, the sampling frequency of the digital control sys-
tem has been set at 10 kHz. This means that both A/D and
Position voltage [V]
0.5 D/A conversions as well as the numerical action necessary
kI = 500
for real-time control must take place within a time span of
100 µs. The conversion time per channel is typically 5 µs
0 for the D/A module, and 2 µs for the A/D module. In other
words, the time available for control action is reduced to
93 µs.
-0.5
Acknowledgements. This research is supported by the Technology Founda-
tion (STW).
-1
References
-1.5
0.3 0.305 0.31 0.315 0.32 0.325 0.33 0.335 1. A.E. Holman, C.D. Laman, P.M.L.O. Scholte, W. Chr. Heerens, F. Tu-
instra: Rev. Sci. Instrum. 67(5), 2274 (1996)
Time [s] 2. C.L. Phillips, H. Troy Nagle: Digital Control System Analysis and De-
sign, 3rd edn. (Prentice-Hall, Englewood Cliffs, NJ 1995)
Fig. 7. Transient response of the stage for different settings of the PID 3. W.Chr. Heerens: J. Phys. E: Sci. Instrum. 19, 897 (1986)
controller
4. W.Chr. Heerens: Mikromechanische Sensor- und Aktorarrays, Novem-
ber, 47 (1996)
5. M. Goldfarb, N. Celanovic: IEEE Control Systems 17(3), 69 (1997)
hysteretic component. From the literature [6–8] a hystere- 6. B.D. Coleman, M.L. Hodgdon: Int. J. Eng. Sci. 24(6), 897 (1986)
7. M.A. Krasnol’skiï, A.V. Pokrovskiï: Systems with Hysteresis (Springer-
sis model in the form of a nonlinear differential equation is Verlag, Berlin, 1989)
known. In view of the assessment that the dynamic and the 8. A.Visintin: Differential Models of Hysteresis (Springer-Verlag, Berlin,
hysteretic behavior of the stage should be regarded as insep- 1994)