Adrian Sima - Academia.edu (original) (raw)

Papers by Adrian Sima

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2018

In this paper we apply digital holographic interferometry as a structural diagnosis tool to inves... more In this paper we apply digital holographic interferometry as a structural diagnosis tool to investigate some surface defects in a XIXth century wooden icon. We use a fully digital experimental set-up for real time acquisition and digital optical reconstruction of holographic sequences. The light source is a He-Ne laser, the digital recording component consists of a CCD camera and a spatial light modulator (SLM) works as a digital holographic projector for the optical reconstruction of the interferograms. Both the acquisition set-up and the reconstruction one are functioning simultaneously therefore the changes in the surface structure are visualized in real-time like a digital holographic interferometry “fringe motion picture” with a 20 fps display. Detachment defects of the paint layer are identified using this non-destructive method and the real-time feature has proven to be useful because it gave a very useful dynamicity to the entire investigation process.

Journal of Optoelectronics and Advanced Materials, 2010

In this paper we present some classical holographic experiments only this time performed in vario... more In this paper we present some classical holographic experiments only this time performed in various digital experimental arrangements. The information of the hologram is either calculated using discrete light diffraction formulae or recorded on a CCD, which takes the place of the registration holographic plate. The information of the hologram may be coded on a SLM which when illuminated reproduces the effects of the diffraction through the hologram or the diffraction may be calculated by a computer and so the output may be obtained more or less digitally. The distinction between virtual and actual digital is stressed. Experiments starting from the simple playback of computer generated Fourier holograms, going through basic interference experiments such as obtaining fringes of equal inclination up to more sophisticated configurations such as Fresnel holograms, are presented with a stress on the digital aspects that make these experiments depart from their classic counterpart.

Electrophoretic deposition (EPD) method is employed to obtain a thick ZnO layer on a ZnO nanorod ... more Electrophoretic deposition (EPD) method is employed to obtain a thick ZnO layer on a ZnO nanorod array prepared in a hydrothermal-electrochemical process. ZnO nanorods have the role to improve the mechanical stability and adherence of ZnO layer deposited by electrophoretic technique. D149 dye is used as sensitizer for ZnO semiconductor. The thus prepared ZnO layer is used for the photoanode of dye-sensitized solar cell (DSC). Performance parameters were extracted from standard current-voltage characteristic (I-V) and charge transfer phenomena occurring at ZnO/dye/electrolyte was evaluated by electrochemical impedance spectroscopy (EIS).

2017 9th International Conference on Electronics, Computers and Artificial Intelligence (ECAI), 2017

Digital holographic interferometry (DHI) increases the advantages of analogical holographic inter... more Digital holographic interferometry (DHI) increases the advantages of analogical holographic interferometry because it eliminates the classical procedures for holographic interferogram acquisition and reconstruction, procedures which involves time and incommodious chemical processing. We propose an optical holographic reconstruction procedure which is faster than a computational one. In this paper we present a full digital experimental set-up used for real-time digital acquisition of a holographic frame sequence and also for real time optical holographic reconstruction using a He-Ne laser, a CCD camera and a phase only spatial light modulator (SLM) HEO1080 from HoloEye having a resolution of 1980×1080 pixels and a 15.36×8.64 mm active area size. Real-time DHI is performed by subtracting consecutive captured frames from a reference frame. A dynamic fringe pattern “motion picture” can be visualized through optical reconstruction. Object lateral displacements are visualized in real-time...

International Journal of Hydrogen Energy, 2021

International Journal of Hydrogen Energy, 2019

h i g h l i g h t s g-C 3 N 4 and TiO 2 /g-C 3 N 4 photoanodes were prepared via spray coating me... more h i g h l i g h t s g-C 3 N 4 and TiO 2 /g-C 3 N 4 photoanodes were prepared via spray coating method. The method allows more controlled deposition of g-C 3 N 4 nanosheet thin films. Films show enhanced visible light absorption and improved photocatalytic activity.

Fusion Engineering and Design, 2019

The design of a superconducting magnet system of a fusion reactor candidate is usually based on t... more The design of a superconducting magnet system of a fusion reactor candidate is usually based on the Cable in Conduit Conductor (CICC) concept. CICC consist of complex structures with several hundreds of highly packed, multistage twisted superconductor and copper strands, cooling structures-all wrapped in thin steel foils and jacketed in relatively thick stainless-steel pipes. As recently demonstrated, such complex morphology can be captured by fully 3D X-ray tomography. One of the three alternative winding pack (WP) options for the toroidal field coils of the European DEMO superconducting magnet system as proposed by the Italian ENEA, features a layer-wound WP design adopting a wind-and-react conductor with high aspect ratio rectangular cross section. A multi-physics modelling requiring high accuracy from the strand to the full-size conductor scale was tested on two X-ray tomography systems. For the microstructural integrity analysis of the internal tin one mm diameter Nb 3 Sn strand, manufactured by Western Superconducting Technologies, a microtomograph with˜1 μm feature recognition was used. For the full-size conductor (66 x 25 mm 2 internal dimensions) a high energy (> 300 kVp) microtomograph with voxel resolution of˜20 μm was employed. Voids and/or geometrical imperfections were detected, accurately pinpointed and locally investigated at high resolution before and after heat treatment. Dimensional measurements on the 3D internal structure of the strand showed the small dimensional changes of the strand after the heat treatment. A significant result was the determination of the twist-pitch factor in a purely non-invasive way. The 3D reconstructions of the

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies VIII, 2016

A fully digital experimental set-up for real-time digital acquisition and digital optical reconst... more A fully digital experimental set-up for real-time digital acquisition and digital optical reconstruction of holographic sequences is presented: a He-Ne laser, a CCD camera and a Phase Only Spatial Light Modulator (SLM) area are part of the set-up. CCD registering and SLM projector are working simultaneously. Using a custom made software of our own, real-time Digital Holographic Interferometry (DHI) “fringe motion pictures” can be performed by subtracting consecutive frames from a reference one and instantly displaying the differences on the SLM illuminated with a playback wave. Phase variations of the objects can be visualized in real-time by observing the interference fringe pattern evolution.

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IV, 2009

Stationary Fizeau fringes, phase shift interferometric fringes, fringes obtained in Murty lateral... more Stationary Fizeau fringes, phase shift interferometric fringes, fringes obtained in Murty lateral shear interferometry, vibration interference pattern as seen by digital speckle pattern interferometer all are digitally captured in specific interferometer set- ups. IntelliWave software produced by Engineering Synthesis Design, Inc. (ESDI) is used to process the fringe patterns. For all these fringe patterns the physical principle and set up

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IV, 2009

A spatial light modulator is a matrix-shaped device able to modify the amplitude or the phase of ... more A spatial light modulator is a matrix-shaped device able to modify the amplitude or the phase of the reflected or transmitted light, which can be operated pixel by pixel independently. This opens new possibilities for rapid and efficient manipulation of the light diffraction but also brings us close to the ambiguous boundary between physical and digital optics, or more precisely

In this paper we describe a traceable to the meter standard method to measure the height of an ar... more In this paper we describe a traceable to the meter standard method to measure the height of an artifact used as a calibrator for observation instruments in nanotechnologies and nanosciences. The artifact is a grating specially manufactured so that its features (height, pitch, width, wall angles) are highly uniform across its area. A Linnik microscope designed for longitudinal (vertical) measurements

In this paper we investigate the vibrations of a square aluminium plate by speckle interferometry... more In this paper we investigate the vibrations of a square aluminium plate by speckle interferometry means. Modes of vibration of this plate are shown as speckle interferograms. As usually is the case with such interferograms, enhancement and filtering of these images is needed after recording. The speckle index and the signal-to-noise ratio (SNR) of the preprocessed interferograms before and after

We discuss an experiment for detecting small deformations by speckle interferometry. Vibration mo... more We discuss an experiment for detecting small deformations by speckle interferometry. Vibration modes of an aluminium plate are observed by digital speckle pattern interferometry (DSPI). A Mach-Zender interferometer arrangement is used and the speckle interferograms are recorded with a CCD camera and processed on a computer. These fringes depend on the path differences due to the vibration of the aluminium plate from its original state. Vibration amplitudes between 0.3-0.6 µm were measured for seven vibration modes.

In this paper a Fourier transform digital holography experimental arrangement is presented. It is... more In this paper a Fourier transform digital holography experimental arrangement is presented. It is actually a hybrid arrangement, half digital half analog. The Fourier hologram was constructed using the analogous means of the so called lensless configuration. The hologram was recorded digitally by a camera with a large CCD array in stead of the recording medium. The recording of the

SPIE Proceedings, 2007

In this paper a simple method for determining the wavelength of an unknown source, (a problem of ... more In this paper a simple method for determining the wavelength of an unknown source, (a problem of great theoretical and practical importance), based on the Moire fringes phenomenon and Fourier analysis is presented and put into practice. The accuracy and the simplicity of the problem makes it attractive and competitive.

Fusion Engineering and Design, 2013

h i g h l i g h t s • A methodology in support of quality controls monitoring of Cable-in-Conduit... more h i g h l i g h t s • A methodology in support of quality controls monitoring of Cable-in-Conduit-Conductor (CICC) to be used in tokamak magnet systems was developed. • High resolution (≈40 m) X-ray tomography images of CICC section up to 300 mm long have been obtained. • All constitutive elements of CICC (316SS jacket, NbTi and Cu strands and external wrapper foil) can be noninvasively inspected. • Derivation of quantities like void fraction and void homogeneity at the local and global level, automatic identification of individual NbTi and Cu strands. • Derivation of geometric parameters like: trajectory, pitch angle and their space distribution.

ifa-mg.ro

1. Introduction Currently, the primary materials choice for ITER (International Thermonuclear Exp... more 1. Introduction Currently, the primary materials choice for ITER (International Thermonuclear Experimental Reactor) is a full beryllium main wall with CFC at the strike points and tungsten at divertor baffles and dome. Since this combination has never been tested in a tokamak, ...

scientificbulletin.upb.ro

Procesul de reconstrucţie tomografică necesită un cost computaţional foarte mare datorită procedu... more Procesul de reconstrucţie tomografică necesită un cost computaţional foarte mare datorită procedurii de "proiecţie înapoi" (backprojection). În acest articol am implementat un astfel de algoritm de reconstrucţie pentru o geometrie paralelă 2D a razelor X. Implementarea a fost realizată în 4 variante: utilizând o singură unitate de calcul, 4 unităţi de calcul (Intel Q6600 la 2.4 GHz şi 8GB memorie ram) împreună cu tehnologia OpenMp, o placă video ce este compatibilă cu tehnologia CUDA şi utilizează memoria globală a acesteia şi ultima variantă aceeaşi placă video însă de data aceasta utilizând memoria texturilor. Atât implementările pe CPU, cât şi cele pe placa grafică folosesc datele în simplă precizie. Cel mai bun timp de calcul a fost obţinut în cazul utilizării plăcii video cu memoria texturilor. Tomographic reconstruction requires a very high computational cost due to its time-consuming backprojection step. In this paper, we implement 2D parallelbeam backprojections on single core processo,on four cores of the same CPU using OpenMP technology and a graphics card Nvdia Tesla 870C using global memory and textures memory CUDA (Compute Unified Device Architecture) architecture. For parallel beam reconstruction, the pixel-driven backprojection program running on the CPU and GPU uses single-precision binary floating-point arithmetic and linear interpolation. With the help of the texture unit we obtained the best computation time.

In this study continuous laser welding of two thickness of aluminium was investigated. Aluminium ... more In this study continuous laser welding of two thickness of aluminium was investigated. Aluminium A 1050 was used. Preliminary study was done to establish the power required for the material to begin to melt and one set of samples were welded in butt joint configuration. The welding was carried out using a solid state laser. The length of the samples welded was 25 mm and the width about 2 mm. Process parameters were optimized for achieving weld without porosity. In this study nondestructive control, like X ray radiography and tomography was done to analyse the defects inside the welding samples.

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2018

In this paper we apply digital holographic interferometry as a structural diagnosis tool to inves... more In this paper we apply digital holographic interferometry as a structural diagnosis tool to investigate some surface defects in a XIXth century wooden icon. We use a fully digital experimental set-up for real time acquisition and digital optical reconstruction of holographic sequences. The light source is a He-Ne laser, the digital recording component consists of a CCD camera and a spatial light modulator (SLM) works as a digital holographic projector for the optical reconstruction of the interferograms. Both the acquisition set-up and the reconstruction one are functioning simultaneously therefore the changes in the surface structure are visualized in real-time like a digital holographic interferometry “fringe motion picture” with a 20 fps display. Detachment defects of the paint layer are identified using this non-destructive method and the real-time feature has proven to be useful because it gave a very useful dynamicity to the entire investigation process.

Journal of Optoelectronics and Advanced Materials, 2010

In this paper we present some classical holographic experiments only this time performed in vario... more In this paper we present some classical holographic experiments only this time performed in various digital experimental arrangements. The information of the hologram is either calculated using discrete light diffraction formulae or recorded on a CCD, which takes the place of the registration holographic plate. The information of the hologram may be coded on a SLM which when illuminated reproduces the effects of the diffraction through the hologram or the diffraction may be calculated by a computer and so the output may be obtained more or less digitally. The distinction between virtual and actual digital is stressed. Experiments starting from the simple playback of computer generated Fourier holograms, going through basic interference experiments such as obtaining fringes of equal inclination up to more sophisticated configurations such as Fresnel holograms, are presented with a stress on the digital aspects that make these experiments depart from their classic counterpart.

Electrophoretic deposition (EPD) method is employed to obtain a thick ZnO layer on a ZnO nanorod ... more Electrophoretic deposition (EPD) method is employed to obtain a thick ZnO layer on a ZnO nanorod array prepared in a hydrothermal-electrochemical process. ZnO nanorods have the role to improve the mechanical stability and adherence of ZnO layer deposited by electrophoretic technique. D149 dye is used as sensitizer for ZnO semiconductor. The thus prepared ZnO layer is used for the photoanode of dye-sensitized solar cell (DSC). Performance parameters were extracted from standard current-voltage characteristic (I-V) and charge transfer phenomena occurring at ZnO/dye/electrolyte was evaluated by electrochemical impedance spectroscopy (EIS).

2017 9th International Conference on Electronics, Computers and Artificial Intelligence (ECAI), 2017

Digital holographic interferometry (DHI) increases the advantages of analogical holographic inter... more Digital holographic interferometry (DHI) increases the advantages of analogical holographic interferometry because it eliminates the classical procedures for holographic interferogram acquisition and reconstruction, procedures which involves time and incommodious chemical processing. We propose an optical holographic reconstruction procedure which is faster than a computational one. In this paper we present a full digital experimental set-up used for real-time digital acquisition of a holographic frame sequence and also for real time optical holographic reconstruction using a He-Ne laser, a CCD camera and a phase only spatial light modulator (SLM) HEO1080 from HoloEye having a resolution of 1980×1080 pixels and a 15.36×8.64 mm active area size. Real-time DHI is performed by subtracting consecutive captured frames from a reference frame. A dynamic fringe pattern “motion picture” can be visualized through optical reconstruction. Object lateral displacements are visualized in real-time...

International Journal of Hydrogen Energy, 2021

International Journal of Hydrogen Energy, 2019

h i g h l i g h t s g-C 3 N 4 and TiO 2 /g-C 3 N 4 photoanodes were prepared via spray coating me... more h i g h l i g h t s g-C 3 N 4 and TiO 2 /g-C 3 N 4 photoanodes were prepared via spray coating method. The method allows more controlled deposition of g-C 3 N 4 nanosheet thin films. Films show enhanced visible light absorption and improved photocatalytic activity.

Fusion Engineering and Design, 2019

The design of a superconducting magnet system of a fusion reactor candidate is usually based on t... more The design of a superconducting magnet system of a fusion reactor candidate is usually based on the Cable in Conduit Conductor (CICC) concept. CICC consist of complex structures with several hundreds of highly packed, multistage twisted superconductor and copper strands, cooling structures-all wrapped in thin steel foils and jacketed in relatively thick stainless-steel pipes. As recently demonstrated, such complex morphology can be captured by fully 3D X-ray tomography. One of the three alternative winding pack (WP) options for the toroidal field coils of the European DEMO superconducting magnet system as proposed by the Italian ENEA, features a layer-wound WP design adopting a wind-and-react conductor with high aspect ratio rectangular cross section. A multi-physics modelling requiring high accuracy from the strand to the full-size conductor scale was tested on two X-ray tomography systems. For the microstructural integrity analysis of the internal tin one mm diameter Nb 3 Sn strand, manufactured by Western Superconducting Technologies, a microtomograph with˜1 μm feature recognition was used. For the full-size conductor (66 x 25 mm 2 internal dimensions) a high energy (> 300 kVp) microtomograph with voxel resolution of˜20 μm was employed. Voids and/or geometrical imperfections were detected, accurately pinpointed and locally investigated at high resolution before and after heat treatment. Dimensional measurements on the 3D internal structure of the strand showed the small dimensional changes of the strand after the heat treatment. A significant result was the determination of the twist-pitch factor in a purely non-invasive way. The 3D reconstructions of the

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies VIII, 2016

A fully digital experimental set-up for real-time digital acquisition and digital optical reconst... more A fully digital experimental set-up for real-time digital acquisition and digital optical reconstruction of holographic sequences is presented: a He-Ne laser, a CCD camera and a Phase Only Spatial Light Modulator (SLM) area are part of the set-up. CCD registering and SLM projector are working simultaneously. Using a custom made software of our own, real-time Digital Holographic Interferometry (DHI) “fringe motion pictures” can be performed by subtracting consecutive frames from a reference one and instantly displaying the differences on the SLM illuminated with a playback wave. Phase variations of the objects can be visualized in real-time by observing the interference fringe pattern evolution.

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IV, 2009

Stationary Fizeau fringes, phase shift interferometric fringes, fringes obtained in Murty lateral... more Stationary Fizeau fringes, phase shift interferometric fringes, fringes obtained in Murty lateral shear interferometry, vibration interference pattern as seen by digital speckle pattern interferometer all are digitally captured in specific interferometer set- ups. IntelliWave software produced by Engineering Synthesis Design, Inc. (ESDI) is used to process the fringe patterns. For all these fringe patterns the physical principle and set up

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IV, 2009

A spatial light modulator is a matrix-shaped device able to modify the amplitude or the phase of ... more A spatial light modulator is a matrix-shaped device able to modify the amplitude or the phase of the reflected or transmitted light, which can be operated pixel by pixel independently. This opens new possibilities for rapid and efficient manipulation of the light diffraction but also brings us close to the ambiguous boundary between physical and digital optics, or more precisely

In this paper we describe a traceable to the meter standard method to measure the height of an ar... more In this paper we describe a traceable to the meter standard method to measure the height of an artifact used as a calibrator for observation instruments in nanotechnologies and nanosciences. The artifact is a grating specially manufactured so that its features (height, pitch, width, wall angles) are highly uniform across its area. A Linnik microscope designed for longitudinal (vertical) measurements

In this paper we investigate the vibrations of a square aluminium plate by speckle interferometry... more In this paper we investigate the vibrations of a square aluminium plate by speckle interferometry means. Modes of vibration of this plate are shown as speckle interferograms. As usually is the case with such interferograms, enhancement and filtering of these images is needed after recording. The speckle index and the signal-to-noise ratio (SNR) of the preprocessed interferograms before and after

We discuss an experiment for detecting small deformations by speckle interferometry. Vibration mo... more We discuss an experiment for detecting small deformations by speckle interferometry. Vibration modes of an aluminium plate are observed by digital speckle pattern interferometry (DSPI). A Mach-Zender interferometer arrangement is used and the speckle interferograms are recorded with a CCD camera and processed on a computer. These fringes depend on the path differences due to the vibration of the aluminium plate from its original state. Vibration amplitudes between 0.3-0.6 µm were measured for seven vibration modes.

In this paper a Fourier transform digital holography experimental arrangement is presented. It is... more In this paper a Fourier transform digital holography experimental arrangement is presented. It is actually a hybrid arrangement, half digital half analog. The Fourier hologram was constructed using the analogous means of the so called lensless configuration. The hologram was recorded digitally by a camera with a large CCD array in stead of the recording medium. The recording of the

SPIE Proceedings, 2007

In this paper a simple method for determining the wavelength of an unknown source, (a problem of ... more In this paper a simple method for determining the wavelength of an unknown source, (a problem of great theoretical and practical importance), based on the Moire fringes phenomenon and Fourier analysis is presented and put into practice. The accuracy and the simplicity of the problem makes it attractive and competitive.

Fusion Engineering and Design, 2013

h i g h l i g h t s • A methodology in support of quality controls monitoring of Cable-in-Conduit... more h i g h l i g h t s • A methodology in support of quality controls monitoring of Cable-in-Conduit-Conductor (CICC) to be used in tokamak magnet systems was developed. • High resolution (≈40 m) X-ray tomography images of CICC section up to 300 mm long have been obtained. • All constitutive elements of CICC (316SS jacket, NbTi and Cu strands and external wrapper foil) can be noninvasively inspected. • Derivation of quantities like void fraction and void homogeneity at the local and global level, automatic identification of individual NbTi and Cu strands. • Derivation of geometric parameters like: trajectory, pitch angle and their space distribution.

ifa-mg.ro

1. Introduction Currently, the primary materials choice for ITER (International Thermonuclear Exp... more 1. Introduction Currently, the primary materials choice for ITER (International Thermonuclear Experimental Reactor) is a full beryllium main wall with CFC at the strike points and tungsten at divertor baffles and dome. Since this combination has never been tested in a tokamak, ...

scientificbulletin.upb.ro

Procesul de reconstrucţie tomografică necesită un cost computaţional foarte mare datorită procedu... more Procesul de reconstrucţie tomografică necesită un cost computaţional foarte mare datorită procedurii de "proiecţie înapoi" (backprojection). În acest articol am implementat un astfel de algoritm de reconstrucţie pentru o geometrie paralelă 2D a razelor X. Implementarea a fost realizată în 4 variante: utilizând o singură unitate de calcul, 4 unităţi de calcul (Intel Q6600 la 2.4 GHz şi 8GB memorie ram) împreună cu tehnologia OpenMp, o placă video ce este compatibilă cu tehnologia CUDA şi utilizează memoria globală a acesteia şi ultima variantă aceeaşi placă video însă de data aceasta utilizând memoria texturilor. Atât implementările pe CPU, cât şi cele pe placa grafică folosesc datele în simplă precizie. Cel mai bun timp de calcul a fost obţinut în cazul utilizării plăcii video cu memoria texturilor. Tomographic reconstruction requires a very high computational cost due to its time-consuming backprojection step. In this paper, we implement 2D parallelbeam backprojections on single core processo,on four cores of the same CPU using OpenMP technology and a graphics card Nvdia Tesla 870C using global memory and textures memory CUDA (Compute Unified Device Architecture) architecture. For parallel beam reconstruction, the pixel-driven backprojection program running on the CPU and GPU uses single-precision binary floating-point arithmetic and linear interpolation. With the help of the texture unit we obtained the best computation time.

In this study continuous laser welding of two thickness of aluminium was investigated. Aluminium ... more In this study continuous laser welding of two thickness of aluminium was investigated. Aluminium A 1050 was used. Preliminary study was done to establish the power required for the material to begin to melt and one set of samples were welded in butt joint configuration. The welding was carried out using a solid state laser. The length of the samples welded was 25 mm and the width about 2 mm. Process parameters were optimized for achieving weld without porosity. In this study nondestructive control, like X ray radiography and tomography was done to analyse the defects inside the welding samples.