671 results on '"thin"'
Search Results
2. Structure and mid-infrared optical properties of spin-coated polyethylene films developed for integrated photonics applications
- Author
-
David, Mauro, Disnan, Davide, Lardschneider, Anna, Wacht, Dominik, Hoang, Hanh T., Ramer, Georg, Detz, Hermann, Lendl, Bernhard, Schmid, Ulrich, Strasser, Gottfried, Hinkov, Borislav, David, Mauro, Disnan, Davide, Lardschneider, Anna, Wacht, Dominik, Hoang, Hanh T., Ramer, Georg, Detz, Hermann, Lendl, Bernhard, Schmid, Ulrich, Strasser, Gottfried, and Hinkov, Borislav
- Abstract
Polyethylene is a promising polymer for mid-infrared integrated optics due to its broad transparency and optimal refractive index. However, simple fabrication protocols that preserve its optical characteristics are needed to foster a wide range of applications and unlock its full potential. This work presents investigations of the optical and structural properties of spin-coated linear low-density polyethylene films fabricated under humidity-controlled conditions. The film thickness on polymer concentration dependence shows a non-linear behavior, in agreement with previously reported theoretical models and allowing predictive concentration-dependent thickness deposition with high repeatability. The surface roughness is on the nanometer-scale for all investigated concentrations between 1% and 10%. The crystallinity of the films was studied with the Raman spectroscopy technique. Mid-infrared ellipsometry measurements show a broad transparency range as expected for bulk material. Layer exposure to solvents revealed good stability of the films, indicating that the fabricated layers can outlast further fabrication steps. These investigations confirm the excellent properties of spin-coated thin films fabricated with our novel method, creating new opportunities for the use in photonic integrated circuits Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
- Published
- 2022
3. Structure and mid-infrared optical properties of spin-coated polyethylene films developed for integrated photonics applications
- Abstract
Polyethylene is a promising polymer for mid-infrared integrated optics due to its broad transparency and optimal refractive index. However, simple fabrication protocols that preserve its optical characteristics are needed to foster a wide range of applications and unlock its full potential. This work presents investigations of the optical and structural properties of spin-coated linear low-density polyethylene films fabricated under humidity-controlled conditions. The film thickness on polymer concentration dependence shows a non-linear behavior, in agreement with previously reported theoretical models and allowing predictive concentration-dependent thickness deposition with high repeatability. The surface roughness is on the nanometer-scale for all investigated concentrations between 1% and 10%. The crystallinity of the films was studied with the Raman spectroscopy technique. Mid-infrared ellipsometry measurements show a broad transparency range as expected for bulk material. Layer exposure to solvents revealed good stability of the films, indicating that the fabricated layers can outlast further fabrication steps. These investigations confirm the excellent properties of spin-coated thin films fabricated with our novel method, creating new opportunities for the use in photonic integrated circuits Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
- Published
- 2022
4. Structure and mid-infrared optical properties of spin-coated polyethylene films developed for integrated photonics applications
- Abstract
Polyethylene is a promising polymer for mid-infrared integrated optics due to its broad transparency and optimal refractive index. However, simple fabrication protocols that preserve its optical characteristics are needed to foster a wide range of applications and unlock its full potential. This work presents investigations of the optical and structural properties of spin-coated linear low-density polyethylene films fabricated under humidity-controlled conditions. The film thickness on polymer concentration dependence shows a non-linear behavior, in agreement with previously reported theoretical models and allowing predictive concentration-dependent thickness deposition with high repeatability. The surface roughness is on the nanometer-scale for all investigated concentrations between 1% and 10%. The crystallinity of the films was studied with the Raman spectroscopy technique. Mid-infrared ellipsometry measurements show a broad transparency range as expected for bulk material. Layer exposure to solvents revealed good stability of the films, indicating that the fabricated layers can outlast further fabrication steps. These investigations confirm the excellent properties of spin-coated thin films fabricated with our novel method, creating new opportunities for the use in photonic integrated circuits Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
- Published
- 2022
5. Structure and mid-infrared optical properties of spin-coated polyethylene films developed for integrated photonics applications
- Author
-
David, Mauro, Disnan, Davide, Lardschneider, Anna, Wacht, Dominik, Hoang, Hanh T., Ramer, Georg, Detz, Hermann, Lendl, Bernhard, Schmid, Ulrich, Strasser, Gottfried, Hinkov, Borislav, David, Mauro, Disnan, Davide, Lardschneider, Anna, Wacht, Dominik, Hoang, Hanh T., Ramer, Georg, Detz, Hermann, Lendl, Bernhard, Schmid, Ulrich, Strasser, Gottfried, and Hinkov, Borislav
- Abstract
Polyethylene is a promising polymer for mid-infrared integrated optics due to its broad transparency and optimal refractive index. However, simple fabrication protocols that preserve its optical characteristics are needed to foster a wide range of applications and unlock its full potential. This work presents investigations of the optical and structural properties of spin-coated linear low-density polyethylene films fabricated under humidity-controlled conditions. The film thickness on polymer concentration dependence shows a non-linear behavior, in agreement with previously reported theoretical models and allowing predictive concentration-dependent thickness deposition with high repeatability. The surface roughness is on the nanometer-scale for all investigated concentrations between 1% and 10%. The crystallinity of the films was studied with the Raman spectroscopy technique. Mid-infrared ellipsometry measurements show a broad transparency range as expected for bulk material. Layer exposure to solvents revealed good stability of the films, indicating that the fabricated layers can outlast further fabrication steps. These investigations confirm the excellent properties of spin-coated thin films fabricated with our novel method, creating new opportunities for the use in photonic integrated circuits Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
- Published
- 2022
6. Vibrations Characterization in Milling of low Stiffness Parts with a Rubber-Based Vacuum Fixture
- Author
-
Ingeniería mecánica, Ingeniaritza mekanikoa, Rubio Mateos, Antonio, Casuso Lomas, Mikel, Rivero Rastrero, María Asunción, Ukar Arrien, Eneko, Lamikiz Mentxaka, Aitzol, Ingeniería mecánica, Ingeniaritza mekanikoa, Rubio Mateos, Antonio, Casuso Lomas, Mikel, Rivero Rastrero, María Asunción, Ukar Arrien, Eneko, and Lamikiz Mentxaka, Aitzol
- Abstract
Fixtures are a critical element in machining operations as they are the interface between the part and the machine. These components are responsible for the precise part location on the machine table and for the proper dynamic stability maintenance during the manufacturing operations. Although these two features are deeply related, they are usually studied separately. On the one hand, diverse adaptable solutions have been developed for the clamping of different variable geometries. Parallelly, the stability of the part has been long studied to reduce the forced vibration and the chatter effects, especially on thin parts machining operations typically performed in the aeronautic field, such as the skin panels milling. The present work proposes a commitment between both features by the presentation of an innovative vacuum fixture based on the use of a vulcanized rubber layer. This solution presents high flexibility as it can be adapted to different geometries while providing a proper damping capacity due to the viscoelastic and elastoplastic behaviour of these compounds. Moreover, the sealing properties of these elastomers provide the perfect combination to transform a rubber layer into a flexible vacuum table. Therefore, in order to validate the suitability of this fixture, a test bench is manufactured and tested under uniaxial compression loads and under real finish milling conditions over AA2024 part samples. Finally, a roughness model is proposed and analysed in order to characterize the part vibration sources.
- Published
- 2021
7. Vibrations Characterization in Milling of low Stiffness Parts with a Rubber-Based Vacuum Fixture
- Author
-
Ingeniería mecánica, Ingeniaritza mekanikoa, Rubio Mateos, Antonio, Casuso Lomas, Mikel, Rivero Rastrero, María Asunción, Ukar Arrien, Eneko, Lamikiz Mentxaka, Aitzol, Ingeniería mecánica, Ingeniaritza mekanikoa, Rubio Mateos, Antonio, Casuso Lomas, Mikel, Rivero Rastrero, María Asunción, Ukar Arrien, Eneko, and Lamikiz Mentxaka, Aitzol
- Abstract
Fixtures are a critical element in machining operations as they are the interface between the part and the machine. These components are responsible for the precise part location on the machine table and for the proper dynamic stability maintenance during the manufacturing operations. Although these two features are deeply related, they are usually studied separately. On the one hand, diverse adaptable solutions have been developed for the clamping of different variable geometries. Parallelly, the stability of the part has been long studied to reduce the forced vibration and the chatter effects, especially on thin parts machining operations typically performed in the aeronautic field, such as the skin panels milling. The present work proposes a commitment between both features by the presentation of an innovative vacuum fixture based on the use of a vulcanized rubber layer. This solution presents high flexibility as it can be adapted to different geometries while providing a proper damping capacity due to the viscoelastic and elastoplastic behaviour of these compounds. Moreover, the sealing properties of these elastomers provide the perfect combination to transform a rubber layer into a flexible vacuum table. Therefore, in order to validate the suitability of this fixture, a test bench is manufactured and tested under uniaxial compression loads and under real finish milling conditions over AA2024 part samples. Finally, a roughness model is proposed and analysed in order to characterize the part vibration sources.
- Published
- 2021
8. Investigation of Post-Darcy Flow in Thin Porous Media
- Author
-
Fallahjoybari, Nima, Lundström, T. Staffan, Fallahjoybari, Nima, and Lundström, T. Staffan
- Abstract
We present numerical simulations of post-Darcy flow in thin porous medium: one consisting of staggered arrangements of circular cylinders and one random distribution of cylinders bounded between walls. The simulations span a range of Reynolds numbers, 40 to 4000, where the pressure drop varies nonlinearly with the average velocity, covering nonlinear laminar flow to the fully turbulent regime. The results are compared to those obtained by replacing the bounding walls with symmetric boundaries with the aim to reveal the effect of bounding walls on microscopic characteristics and macroscopic measures, i.e., pressure drop, hydrodynamic dispersion and Reynolds stresses. We use large eddy simulation to directly calculate the Reynolds stresses and turbulent intensity. The simulations show that vortical structures emerge at the boundary between the cylinders and the bounding walls causing a difference between the microscopic flow in the confined and non-confined porous media. This affects the averaged values of pressure drop, the hydrodynamic dispersion and the Reynolds stresses. Finally, the distance between the bounding walls is altered with the particle Reynolds number kept constant. It is observed that the difference between results calculated in confined and non-confined cases increases when the bounding walls are narrower.
- Published
- 2021
- Full Text
- View/download PDF
9. Investigation of Post-Darcy Flow in Thin Porous Media
- Author
-
Fallahjoybari, Nima, Lundström, T. Staffan, Fallahjoybari, Nima, and Lundström, T. Staffan
- Abstract
We present numerical simulations of post-Darcy flow in thin porous medium: one consisting of staggered arrangements of circular cylinders and one random distribution of cylinders bounded between walls. The simulations span a range of Reynolds numbers, 40 to 4000, where the pressure drop varies nonlinearly with the average velocity, covering nonlinear laminar flow to the fully turbulent regime. The results are compared to those obtained by replacing the bounding walls with symmetric boundaries with the aim to reveal the effect of bounding walls on microscopic characteristics and macroscopic measures, i.e., pressure drop, hydrodynamic dispersion and Reynolds stresses. We use large eddy simulation to directly calculate the Reynolds stresses and turbulent intensity. The simulations show that vortical structures emerge at the boundary between the cylinders and the bounding walls causing a difference between the microscopic flow in the confined and non-confined porous media. This affects the averaged values of pressure drop, the hydrodynamic dispersion and the Reynolds stresses. Finally, the distance between the bounding walls is altered with the particle Reynolds number kept constant. It is observed that the difference between results calculated in confined and non-confined cases increases when the bounding walls are narrower.
- Published
- 2021
- Full Text
- View/download PDF
10. Vibrations Characterization in Milling of low Stiffness Parts with a Rubber-Based Vacuum Fixture
- Author
-
Ingeniería mecánica, Ingeniaritza mekanikoa, Rubio Mateos, Antonio, Casuso Lomas, Mikel, Rivero Rastrero, María Asunción, Ukar Arrien, Eneko, Lamikiz Mentxaka, Aitzol, Ingeniería mecánica, Ingeniaritza mekanikoa, Rubio Mateos, Antonio, Casuso Lomas, Mikel, Rivero Rastrero, María Asunción, Ukar Arrien, Eneko, and Lamikiz Mentxaka, Aitzol
- Abstract
Fixtures are a critical element in machining operations as they are the interface between the part and the machine. These components are responsible for the precise part location on the machine table and for the proper dynamic stability maintenance during the manufacturing operations. Although these two features are deeply related, they are usually studied separately. On the one hand, diverse adaptable solutions have been developed for the clamping of different variable geometries. Parallelly, the stability of the part has been long studied to reduce the forced vibration and the chatter effects, especially on thin parts machining operations typically performed in the aeronautic field, such as the skin panels milling. The present work proposes a commitment between both features by the presentation of an innovative vacuum fixture based on the use of a vulcanized rubber layer. This solution presents high flexibility as it can be adapted to different geometries while providing a proper damping capacity due to the viscoelastic and elastoplastic behaviour of these compounds. Moreover, the sealing properties of these elastomers provide the perfect combination to transform a rubber layer into a flexible vacuum table. Therefore, in order to validate the suitability of this fixture, a test bench is manufactured and tested under uniaxial compression loads and under real finish milling conditions over AA2024 part samples. Finally, a roughness model is proposed and analysed in order to characterize the part vibration sources.
- Published
- 2021
11. Investigation of Post-Darcy Flow in Thin Porous Media
- Author
-
Fallahjoybari, Nima, Lundström, T. Staffan, Fallahjoybari, Nima, and Lundström, T. Staffan
- Abstract
We present numerical simulations of post-Darcy flow in thin porous medium: one consisting of staggered arrangements of circular cylinders and one random distribution of cylinders bounded between walls. The simulations span a range of Reynolds numbers, 40 to 4000, where the pressure drop varies nonlinearly with the average velocity, covering nonlinear laminar flow to the fully turbulent regime. The results are compared to those obtained by replacing the bounding walls with symmetric boundaries with the aim to reveal the effect of bounding walls on microscopic characteristics and macroscopic measures, i.e., pressure drop, hydrodynamic dispersion and Reynolds stresses. We use large eddy simulation to directly calculate the Reynolds stresses and turbulent intensity. The simulations show that vortical structures emerge at the boundary between the cylinders and the bounding walls causing a difference between the microscopic flow in the confined and non-confined porous media. This affects the averaged values of pressure drop, the hydrodynamic dispersion and the Reynolds stresses. Finally, the distance between the bounding walls is altered with the particle Reynolds number kept constant. It is observed that the difference between results calculated in confined and non-confined cases increases when the bounding walls are narrower.
- Published
- 2021
- Full Text
- View/download PDF
12. Investigation of Post-Darcy Flow in Thin Porous Media
- Author
-
Fallahjoybari, Nima, Lundström, T. Staffan, Fallahjoybari, Nima, and Lundström, T. Staffan
- Abstract
We present numerical simulations of post-Darcy flow in thin porous medium: one consisting of staggered arrangements of circular cylinders and one random distribution of cylinders bounded between walls. The simulations span a range of Reynolds numbers, 40 to 4000, where the pressure drop varies nonlinearly with the average velocity, covering nonlinear laminar flow to the fully turbulent regime. The results are compared to those obtained by replacing the bounding walls with symmetric boundaries with the aim to reveal the effect of bounding walls on microscopic characteristics and macroscopic measures, i.e., pressure drop, hydrodynamic dispersion and Reynolds stresses. We use large eddy simulation to directly calculate the Reynolds stresses and turbulent intensity. The simulations show that vortical structures emerge at the boundary between the cylinders and the bounding walls causing a difference between the microscopic flow in the confined and non-confined porous media. This affects the averaged values of pressure drop, the hydrodynamic dispersion and the Reynolds stresses. Finally, the distance between the bounding walls is altered with the particle Reynolds number kept constant. It is observed that the difference between results calculated in confined and non-confined cases increases when the bounding walls are narrower.
- Published
- 2021
- Full Text
- View/download PDF
13. Investigation of Post-Darcy Flow in Thin Porous Media
- Author
-
Fallahjoybari, Nima, Lundström, T. Staffan, Fallahjoybari, Nima, and Lundström, T. Staffan
- Abstract
We present numerical simulations of post-Darcy flow in thin porous medium: one consisting of staggered arrangements of circular cylinders and one random distribution of cylinders bounded between walls. The simulations span a range of Reynolds numbers, 40 to 4000, where the pressure drop varies nonlinearly with the average velocity, covering nonlinear laminar flow to the fully turbulent regime. The results are compared to those obtained by replacing the bounding walls with symmetric boundaries with the aim to reveal the effect of bounding walls on microscopic characteristics and macroscopic measures, i.e., pressure drop, hydrodynamic dispersion and Reynolds stresses. We use large eddy simulation to directly calculate the Reynolds stresses and turbulent intensity. The simulations show that vortical structures emerge at the boundary between the cylinders and the bounding walls causing a difference between the microscopic flow in the confined and non-confined porous media. This affects the averaged values of pressure drop, the hydrodynamic dispersion and the Reynolds stresses. Finally, the distance between the bounding walls is altered with the particle Reynolds number kept constant. It is observed that the difference between results calculated in confined and non-confined cases increases when the bounding walls are narrower.
- Published
- 2021
- Full Text
- View/download PDF
14. Flexible, Temperature-Resistant, and Fatigue-Free Ferroelectric Memory Based on Bi(Fe0.93Mn0.05Ti0.02)O3 Thin Film
- Author
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Yang, Changhong, Han, Yajie, Qian, Jin, Lv, Panpan, Lin, Xiujuan, Huang, Shifeng, Cheng, Zhenxiang, Yang, Changhong, Han, Yajie, Qian, Jin, Lv, Panpan, Lin, Xiujuan, Huang, Shifeng, and Cheng, Zhenxiang
- Published
- 2019
15. Chemical Solution Route for High‐Quality Multiferroic BiFeO3 Thin Films
- Author
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Yang, Bingbing, Jin, Linghua, Wei, Renhuai, Tang, Xianwu, Hu, Ling, Tong, Peng, Yang, Jie, Song, Wenhai, Dai, Jianming, Zhu, Xuebin, Sun, Yuping, Zhang, Shujun, Wang, Xiaolin, Cheng, Zhenxiang, Yang, Bingbing, Jin, Linghua, Wei, Renhuai, Tang, Xianwu, Hu, Ling, Tong, Peng, Yang, Jie, Song, Wenhai, Dai, Jianming, Zhu, Xuebin, Sun, Yuping, Zhang, Shujun, Wang, Xiaolin, and Cheng, Zhenxiang
- Abstract
© 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Bismuth ferrite (BiFeO3) has recently become interesting as a room-temperature multiferroic material, and a variety of prototype devices have been designed based on its thin films. A low-cost and simple processing technique for large-area and high-quality BiFeO3 thin films that is compatible with current semiconductor technologies is therefore urgently needed. Development of BiFeO3 thin films is summarized with a specific focus on the chemical solution route. By a systematic analysis of the recent progress in chemical-route-derived BiFeO3 thin films, the challenges of these films are highlighted. An all-solution chemical-solution deposition (AS-CSD) for BiFeO3 thin films with different orientation epitaxial on various oxide bottom electrodes is introduced and a comprehensive study of the growth, structure, and ferroelectric properties of these films is provided. A facile low-cost route to prepare large-area high-quality epitaxial BFO thin films with a comprehensive understanding of the film thickness, stoichiometry, crystal orientation, ferroelectric properties, and bottom electrode effects on evolutions of microstructures is provided. This work paves the way for the fabrication of devices based on BiFeO3 thin films.
- Published
- 2019
16. Modification of pinning in YBa 2 Cu 3 O 7 thin films by substrate annealing
- Author
-
Jones, Antony, Lam, Simon K. H, Du, Jia, Rubanov, Sergey, Pan, Alexey, Jones, Antony, Lam, Simon K. H, Du, Jia, Rubanov, Sergey, and Pan, Alexey
- Abstract
To improve the usefulness of superconducting devices the critical current density (Jc) oftenneeds to be improved ormodified. This can simply be done by increasing the amount of defects present, allowing more magnetic flux to be trapped. These defects can be introduced artificially after deposition by use of for instance controlled holes throughout the surface (antidots), or prior to deposition by manipulating the procedure or substrate type/surface. In this paper, LaAlO3 substrates were annealed at 1000 °C for 2 h prior to deposition of approximately 250 nm of YBa 2 Cu 3 O 7 . Across several depositions, on average the Jc of the annealed substrate film is improved∼10-15% relative to a plain substrate film. Aside from a Jc enhancement, the annealed substrate samples were found to have a much higher consistency between depositions, particularly at lower applied magnetic fields. Furthermore, ion beam etching is often required on the substrate for fabrication of superconducting devices. This paper has shown that annealing can restore the substrate surface to the same quality as the manufactured plain substrate, based on the very similar Jc values.
- Published
- 2019
17. Chemical Solution Route for High‐Quality Multiferroic BiFeO3 Thin Films
- Author
-
Yang, Bingbing, Jin, Linghua, Wei, Renhuai, Tang, Xianwu, Hu, Ling, Tong, Peng, Yang, Jie, Song, Wenhai, Dai, Jianming, Zhu, Xuebin, Sun, Yuping, Zhang, Shujun, Wang, Xiaolin, Cheng, Zhenxiang, Yang, Bingbing, Jin, Linghua, Wei, Renhuai, Tang, Xianwu, Hu, Ling, Tong, Peng, Yang, Jie, Song, Wenhai, Dai, Jianming, Zhu, Xuebin, Sun, Yuping, Zhang, Shujun, Wang, Xiaolin, and Cheng, Zhenxiang
- Abstract
© 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Bismuth ferrite (BiFeO3) has recently become interesting as a room-temperature multiferroic material, and a variety of prototype devices have been designed based on its thin films. A low-cost and simple processing technique for large-area and high-quality BiFeO3 thin films that is compatible with current semiconductor technologies is therefore urgently needed. Development of BiFeO3 thin films is summarized with a specific focus on the chemical solution route. By a systematic analysis of the recent progress in chemical-route-derived BiFeO3 thin films, the challenges of these films are highlighted. An all-solution chemical-solution deposition (AS-CSD) for BiFeO3 thin films with different orientation epitaxial on various oxide bottom electrodes is introduced and a comprehensive study of the growth, structure, and ferroelectric properties of these films is provided. A facile low-cost route to prepare large-area high-quality epitaxial BFO thin films with a comprehensive understanding of the film thickness, stoichiometry, crystal orientation, ferroelectric properties, and bottom electrode effects on evolutions of microstructures is provided. This work paves the way for the fabrication of devices based on BiFeO3 thin films.
- Published
- 2019
18. Modification of pinning in YBa 2 Cu 3 O 7 thin films by substrate annealing
- Author
-
Jones, Antony, Lam, Simon K. H, Du, Jia, Rubanov, Sergey, Pan, Alexey, Jones, Antony, Lam, Simon K. H, Du, Jia, Rubanov, Sergey, and Pan, Alexey
- Abstract
To improve the usefulness of superconducting devices the critical current density (Jc) oftenneeds to be improved ormodified. This can simply be done by increasing the amount of defects present, allowing more magnetic flux to be trapped. These defects can be introduced artificially after deposition by use of for instance controlled holes throughout the surface (antidots), or prior to deposition by manipulating the procedure or substrate type/surface. In this paper, LaAlO3 substrates were annealed at 1000 °C for 2 h prior to deposition of approximately 250 nm of YBa 2 Cu 3 O 7 . Across several depositions, on average the Jc of the annealed substrate film is improved∼10-15% relative to a plain substrate film. Aside from a Jc enhancement, the annealed substrate samples were found to have a much higher consistency between depositions, particularly at lower applied magnetic fields. Furthermore, ion beam etching is often required on the substrate for fabrication of superconducting devices. This paper has shown that annealing can restore the substrate surface to the same quality as the manufactured plain substrate, based on the very similar Jc values.
- Published
- 2019
19. How do “selfies” impact adolescents’ well-being and body confidence? A narrative review
- Author
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McLean, S A, Jarman, Hannah K., Rodgers, R F, McLean, S A, Jarman, Hannah K., and Rodgers, R F
- Published
- 2019
20. Investigation of magnetic order in nickel-5d transition metal systems
- Author
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Papadopoulos, Konstantinos and Papadopoulos, Konstantinos
- Abstract
Double perovskite materials exhibit alterations in magnetic order through manipulation oftheir crystal structure. Certain ultra thin metallic bilayers can create an exotic magnetic stateof confined spin textures called skyrmions. In both cases, new atomic arrangements leadto new electrical and magnetic properties. The following work comprises two studies, bothof which examine the magnetic properties of transition metals in either powder or thin filmsamples. The first part is dedicated to a series of muon spin rotation and relaxation (muSR)experiments on a LaSrNiReO6, double perovskite, powder sample. In the muSR technique, aspin polarized muon beam is focused onto a powder envelope in low pressure and temperatureconditions. The spins of the implanted muons evolve depending on the intrinsic or externallyapplied magnetic field according to Larmor precession. The measurement is based onthe detection of decay positrons that carry this precession information on their preferreddecay directions. Measurements that were realized in wTF, ZF and LF setups, reveal asecond transition to magnetic order at Tc ≃ 22K, below a transition that was observed at T =261K from magnetic susceptibility measurements. The experimental results point to threemagnetic phases, paramagnetic for T > 261K, dilute ferrimagnetic for 22 < T < 261K and amagnetically ordered state for T < 22K, that may implicate ferro- and antiferromagnetismfrom Ni sublattices and Ni-Re interactions. The second part follows an attempt to produce and characterize ultra thin bilayer filmsfor the observation of interfacial chiral structures and skyrmions. Co/Fe/MgO (100) andW/Ni/Cu (100) bilayers were grown with magnetron sputter deposition in various layerthicknesses and their structure was determined by X-ray reflectometry (XRR). The XRRscans presented a relatively thick-layered Co/Fe/MgO film, while extremely thin and roughW/Ni/Cu bilayers, for the purposes of studying films with broken interfacial inversionsy
- Published
- 2019
21. Chemical Solution Route for High‐Quality Multiferroic BiFeO3 Thin Films
- Author
-
Yang, Bingbing, Jin, Linghua, Wei, Renhuai, Tang, Xianwu, Hu, Ling, Tong, Peng, Yang, Jie, Song, Wenhai, Dai, Jianming, Zhu, Xuebin, Sun, Yuping, Zhang, Shujun, Wang, Xiaolin, Cheng, Zhenxiang, Yang, Bingbing, Jin, Linghua, Wei, Renhuai, Tang, Xianwu, Hu, Ling, Tong, Peng, Yang, Jie, Song, Wenhai, Dai, Jianming, Zhu, Xuebin, Sun, Yuping, Zhang, Shujun, Wang, Xiaolin, and Cheng, Zhenxiang
- Abstract
© 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Bismuth ferrite (BiFeO3) has recently become interesting as a room-temperature multiferroic material, and a variety of prototype devices have been designed based on its thin films. A low-cost and simple processing technique for large-area and high-quality BiFeO3 thin films that is compatible with current semiconductor technologies is therefore urgently needed. Development of BiFeO3 thin films is summarized with a specific focus on the chemical solution route. By a systematic analysis of the recent progress in chemical-route-derived BiFeO3 thin films, the challenges of these films are highlighted. An all-solution chemical-solution deposition (AS-CSD) for BiFeO3 thin films with different orientation epitaxial on various oxide bottom electrodes is introduced and a comprehensive study of the growth, structure, and ferroelectric properties of these films is provided. A facile low-cost route to prepare large-area high-quality epitaxial BFO thin films with a comprehensive understanding of the film thickness, stoichiometry, crystal orientation, ferroelectric properties, and bottom electrode effects on evolutions of microstructures is provided. This work paves the way for the fabrication of devices based on BiFeO3 thin films.
- Published
- 2019
22. Investigation of magnetic order in nickel-5d transition metal systems
- Author
-
Papadopoulos, Konstantinos and Papadopoulos, Konstantinos
- Abstract
Double perovskite materials exhibit alterations in magnetic order through manipulation oftheir crystal structure. Certain ultra thin metallic bilayers can create an exotic magnetic stateof confined spin textures called skyrmions. In both cases, new atomic arrangements leadto new electrical and magnetic properties. The following work comprises two studies, bothof which examine the magnetic properties of transition metals in either powder or thin filmsamples. The first part is dedicated to a series of muon spin rotation and relaxation (muSR)experiments on a LaSrNiReO6, double perovskite, powder sample. In the muSR technique, aspin polarized muon beam is focused onto a powder envelope in low pressure and temperatureconditions. The spins of the implanted muons evolve depending on the intrinsic or externallyapplied magnetic field according to Larmor precession. The measurement is based onthe detection of decay positrons that carry this precession information on their preferreddecay directions. Measurements that were realized in wTF, ZF and LF setups, reveal asecond transition to magnetic order at Tc ≃ 22K, below a transition that was observed at T =261K from magnetic susceptibility measurements. The experimental results point to threemagnetic phases, paramagnetic for T > 261K, dilute ferrimagnetic for 22 < T < 261K and amagnetically ordered state for T < 22K, that may implicate ferro- and antiferromagnetismfrom Ni sublattices and Ni-Re interactions. The second part follows an attempt to produce and characterize ultra thin bilayer filmsfor the observation of interfacial chiral structures and skyrmions. Co/Fe/MgO (100) andW/Ni/Cu (100) bilayers were grown with magnetron sputter deposition in various layerthicknesses and their structure was determined by X-ray reflectometry (XRR). The XRRscans presented a relatively thick-layered Co/Fe/MgO film, while extremely thin and roughW/Ni/Cu bilayers, for the purposes of studying films with broken interfacial inversionsy
- Published
- 2019
23. Chemical Solution Route for High‐Quality Multiferroic BiFeO3 Thin Films
- Author
-
Yang, Bingbing, Jin, Linghua, Wei, Renhuai, Tang, Xianwu, Hu, Ling, Tong, Peng, Yang, Jie, Song, Wenhai, Dai, Jianming, Zhu, Xuebin, Sun, Yuping, Zhang, Shujun, Wang, Xiaolin, Cheng, Zhenxiang, Yang, Bingbing, Jin, Linghua, Wei, Renhuai, Tang, Xianwu, Hu, Ling, Tong, Peng, Yang, Jie, Song, Wenhai, Dai, Jianming, Zhu, Xuebin, Sun, Yuping, Zhang, Shujun, Wang, Xiaolin, and Cheng, Zhenxiang
- Abstract
© 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Bismuth ferrite (BiFeO3) has recently become interesting as a room-temperature multiferroic material, and a variety of prototype devices have been designed based on its thin films. A low-cost and simple processing technique for large-area and high-quality BiFeO3 thin films that is compatible with current semiconductor technologies is therefore urgently needed. Development of BiFeO3 thin films is summarized with a specific focus on the chemical solution route. By a systematic analysis of the recent progress in chemical-route-derived BiFeO3 thin films, the challenges of these films are highlighted. An all-solution chemical-solution deposition (AS-CSD) for BiFeO3 thin films with different orientation epitaxial on various oxide bottom electrodes is introduced and a comprehensive study of the growth, structure, and ferroelectric properties of these films is provided. A facile low-cost route to prepare large-area high-quality epitaxial BFO thin films with a comprehensive understanding of the film thickness, stoichiometry, crystal orientation, ferroelectric properties, and bottom electrode effects on evolutions of microstructures is provided. This work paves the way for the fabrication of devices based on BiFeO3 thin films.
- Published
- 2019
24. Modification of pinning in YBa 2 Cu 3 O 7 thin films by substrate annealing
- Author
-
Jones, Antony, Lam, Simon K. H, Du, Jia, Rubanov, Sergey, Pan, Alexey, Jones, Antony, Lam, Simon K. H, Du, Jia, Rubanov, Sergey, and Pan, Alexey
- Abstract
To improve the usefulness of superconducting devices the critical current density (Jc) oftenneeds to be improved ormodified. This can simply be done by increasing the amount of defects present, allowing more magnetic flux to be trapped. These defects can be introduced artificially after deposition by use of for instance controlled holes throughout the surface (antidots), or prior to deposition by manipulating the procedure or substrate type/surface. In this paper, LaAlO3 substrates were annealed at 1000 °C for 2 h prior to deposition of approximately 250 nm of YBa 2 Cu 3 O 7 . Across several depositions, on average the Jc of the annealed substrate film is improved∼10-15% relative to a plain substrate film. Aside from a Jc enhancement, the annealed substrate samples were found to have a much higher consistency between depositions, particularly at lower applied magnetic fields. Furthermore, ion beam etching is often required on the substrate for fabrication of superconducting devices. This paper has shown that annealing can restore the substrate surface to the same quality as the manufactured plain substrate, based on the very similar Jc values.
- Published
- 2019
25. Modification of pinning in YBa 2 Cu 3 O 7 thin films by substrate annealing
- Author
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Jones, Antony, Lam, Simon K. H, Du, Jia, Rubanov, Sergey, Pan, Alexey, Jones, Antony, Lam, Simon K. H, Du, Jia, Rubanov, Sergey, and Pan, Alexey
- Abstract
To improve the usefulness of superconducting devices the critical current density (Jc) oftenneeds to be improved ormodified. This can simply be done by increasing the amount of defects present, allowing more magnetic flux to be trapped. These defects can be introduced artificially after deposition by use of for instance controlled holes throughout the surface (antidots), or prior to deposition by manipulating the procedure or substrate type/surface. In this paper, LaAlO3 substrates were annealed at 1000 °C for 2 h prior to deposition of approximately 250 nm of YBa 2 Cu 3 O 7 . Across several depositions, on average the Jc of the annealed substrate film is improved∼10-15% relative to a plain substrate film. Aside from a Jc enhancement, the annealed substrate samples were found to have a much higher consistency between depositions, particularly at lower applied magnetic fields. Furthermore, ion beam etching is often required on the substrate for fabrication of superconducting devices. This paper has shown that annealing can restore the substrate surface to the same quality as the manufactured plain substrate, based on the very similar Jc values.
- Published
- 2019
26. This title is unavailable for guests, please login to see more information.
- Author
-
Hu, Songbai, Cazorla, Claudio, Xiang, Feixiang, Ma, Hongfei, Wang, Jianyuan, Wang, Jianbo, Wang, Xiaolin, Ulrich, Clemens, Chen, Lang, Seidel, Jan, Hu, Songbai, Cazorla, Claudio, Xiang, Feixiang, Ma, Hongfei, Wang, Jianyuan, Wang, Jianbo, Wang, Xiaolin, Ulrich, Clemens, Chen, Lang, and Seidel, Jan
- Published
- 2018
27. Is fat the new skinny? : A study on weight and perception of models in green marketing
- Author
-
Wagrelius, Oskar, Eriksson, Sara, Wagrelius, Oskar, and Eriksson, Sara
- Abstract
Title: Is fat the new skinny? A study on weight and perception of models in green marketing. Date: 2018-05-22 Level: Bachelor Thesis in International Marketing Author: Oskar Wagrelius & Sara Eriksson Supervisor: Ulf Aagerup Problem formulation: How does the perceived weight and warmth/competence of a model in green marketing affect sales through perceived greenness and attractiveness? Purpose: The purpose of this study is to increase the knowledge, for brands being green, about how the choice of models in their advertisement will impact the brand's perception and affect greenness, attractiveness, and sales. The goal is to understand if the choice of a diverse model (considering weight) might be more effective considering green marketing and brands who want to be perceived as warm and/or competent. Theoretical framework: In this thesis, the theoretical framework is made up of existing theories on brand positioning, brand identity, consumer behavior, the perception of people and the usage of models. Methodology: This thesis is conducted with a deductive approach through a quantitative study made up of 131 respondents since non-coffee drinkers and non-coffee buying respondents as well as, non-Swedish people were excluded from participating. A total of 160 people responded to the online survey. The groups were randomized as to which one of four different surveys they got to answer. Secondary sources are scientific articles and books, journals as well as websites since the topic is in an academic viewpoint under-researched. Empirical findings: This thesis and its findings consist of an analysis of the quantitative study which is presented through theoretical models, figures, diagrams and tables as well as text. Conclusion: The findings in this thesis shows that green products have a higher purchase propensity than neutral products. Therefore the first assumption is considered to be true. The second and third assumptions are however falsified through the findings that
- Published
- 2018
28. Upscaling thin film solar cells for water treatment devices
- Author
-
Maggioni, Paolo (author) and Maggioni, Paolo (author)
- Abstract
The availability of clean drinking water and various energy sources has always been taken for granted and considered to be infinite throughout human history. However, nowadays, we have reached a historical moment in which we are over-exploiting the Earth's resources. The reduction of the high level of pollution in the air and in the water is one of the main challenges that the next generations will have to face. Photovoltaic technologies offer a clean and cheap solution for both water purification and hydrogen generation for energy storage. The main goal of this thesis is to upscale lab-scale thin film solar cells, by a factor of 600, optimized for water treatment devices. To this end, two alternative solutions have been explored. On the one hand, a metallic front contact grid has been designed to minimize the power losses in large area pin superstrate solar cells. On the other hand, a thin film mini-module has been manufactured by isolating small area nip substrate solar cells and connecting them in parallel. The implementation of the front metallic grid has enabled the upscaling of pin superstrate amorphous silicon solar cells by a factor of around 10. Additionally, the laser ablation process needed for dividing the sample into multiple cells has been studied and optimized for nip substrate amorphous silicon devices. Finally, some of the major problems that cause the formation of shunts have been identified. However, the relatively high density of shunts through the amorphous silicon bulk prevents the device from achieving higher efficiencies at larger dimensions.
- Published
- 2018
29. DUAL-HARDNESS TITANIUM BODY ARMOR FOR CONCEALABLE APPLICATIONS
- Author
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Gamache, Raymond M., Kartalov, Emil P., Physics (PH), McLaurin, Berl, Gamache, Raymond M., Kartalov, Emil P., Physics (PH), and McLaurin, Berl
- Abstract
A current need exists to develop a lightweight, low-profile armor system capable of defeating a 7.62x39mm ball round at muzzle velocity. Three design requirements must be met within the development of this system: areal density less than 5lbs/ft2, an overall thickness of less than 8mm, and formability to match torso contours. This study focuses on pure titanium (Ti) (Grade 2) and a single titanium alloy, Ti6Al-4V (Grade 5). Both materials exhibit superplastic behavior to enable shaping to the torso. Initial studies focus on laminate systems of both homogeneous and heterogeneous layered structures to investigate pressure reduction mechanisms. In addition to layered systems, hard front face coatings are studied as an alternative approach to reducing the penetration pressure through initial blunting of the incident projectile. Test configurations are investigated both experimentally and through hydrocode modeling., http://archive.org/details/dualhardnesstita1094559720, Ensign, United States Navy, Approved for public release; distribution is unlimited.
- Published
- 2018
30. Upscaling thin film solar cells for water treatment devices
- Author
-
Maggioni, Paolo (author) and Maggioni, Paolo (author)
- Abstract
The availability of clean drinking water and various energy sources has always been taken for granted and considered to be infinite throughout human history. However, nowadays, we have reached a historical moment in which we are over-exploiting the Earth's resources. The reduction of the high level of pollution in the air and in the water is one of the main challenges that the next generations will have to face. Photovoltaic technologies offer a clean and cheap solution for both water purification and hydrogen generation for energy storage. The main goal of this thesis is to upscale lab-scale thin film solar cells, by a factor of 600, optimized for water treatment devices. To this end, two alternative solutions have been explored. On the one hand, a metallic front contact grid has been designed to minimize the power losses in large area pin superstrate solar cells. On the other hand, a thin film mini-module has been manufactured by isolating small area nip substrate solar cells and connecting them in parallel. The implementation of the front metallic grid has enabled the upscaling of pin superstrate amorphous silicon solar cells by a factor of around 10. Additionally, the laser ablation process needed for dividing the sample into multiple cells has been studied and optimized for nip substrate amorphous silicon devices. Finally, some of the major problems that cause the formation of shunts have been identified. However, the relatively high density of shunts through the amorphous silicon bulk prevents the device from achieving higher efficiencies at larger dimensions.
- Published
- 2018
31. Is fat the new skinny? : A study on weight and perception of models in green marketing
- Author
-
Wagrelius, Oskar, Eriksson, Sara, Wagrelius, Oskar, and Eriksson, Sara
- Abstract
Title: Is fat the new skinny? A study on weight and perception of models in green marketing. Date: 2018-05-22 Level: Bachelor Thesis in International Marketing Author: Oskar Wagrelius & Sara Eriksson Supervisor: Ulf Aagerup Problem formulation: How does the perceived weight and warmth/competence of a model in green marketing affect sales through perceived greenness and attractiveness? Purpose: The purpose of this study is to increase the knowledge, for brands being green, about how the choice of models in their advertisement will impact the brand's perception and affect greenness, attractiveness, and sales. The goal is to understand if the choice of a diverse model (considering weight) might be more effective considering green marketing and brands who want to be perceived as warm and/or competent. Theoretical framework: In this thesis, the theoretical framework is made up of existing theories on brand positioning, brand identity, consumer behavior, the perception of people and the usage of models. Methodology: This thesis is conducted with a deductive approach through a quantitative study made up of 131 respondents since non-coffee drinkers and non-coffee buying respondents as well as, non-Swedish people were excluded from participating. A total of 160 people responded to the online survey. The groups were randomized as to which one of four different surveys they got to answer. Secondary sources are scientific articles and books, journals as well as websites since the topic is in an academic viewpoint under-researched. Empirical findings: This thesis and its findings consist of an analysis of the quantitative study which is presented through theoretical models, figures, diagrams and tables as well as text. Conclusion: The findings in this thesis shows that green products have a higher purchase propensity than neutral products. Therefore the first assumption is considered to be true. The second and third assumptions are however falsified through the findings that
- Published
- 2018
32. Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain
- Author
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Suzuki, Norihiro, Osada, Minoru, Billah, Md Motasim, Bando, Yoshio, Yamauchi, Yusuke, Hossain, Md. Shahriar Al, Suzuki, Norihiro, Osada, Minoru, Billah, Md Motasim, Bando, Yoshio, Yamauchi, Yusuke, and Hossain, Md. Shahriar Al
- Abstract
Barium titanate (BaTiO 3 , hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 °C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications. In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.
- Published
- 2018
33. Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain
- Author
-
Suzuki, Norihiro, Osada, Minoru, Billah, Md Motasim, Bando, Yoshio, Yamauchi, Yusuke, Hossain, Md. Shahriar Al, Suzuki, Norihiro, Osada, Minoru, Billah, Md Motasim, Bando, Yoshio, Yamauchi, Yusuke, and Hossain, Md. Shahriar Al
- Abstract
Barium titanate (BaTiO 3 , hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 °C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications. In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.
- Published
- 2018
34. Design, fabrication and testing of a prototype, thin-vaulted, unreinforced concrete floor
- Author
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Universitat Politècnica de Catalunya. Departament d'Enginyeria Civil i Ambiental, Liew, Andrew, López López, David, Van Mele, Tom, Block, Philippe, Universitat Politècnica de Catalunya. Departament d'Enginyeria Civil i Ambiental, Liew, Andrew, López López, David, Van Mele, Tom, and Block, Philippe
- Abstract
This paper describes the concept, form finding, fabrication and experimental testing of a prototype floor system, derived from principles of shallow arching action, to initiate internal compressive stresses rather than exclusively flexural stresses. This vaulting in a floor system leads to a lightweight structural element, with significant weight savings compared to traditional concrete floor slabs. The form finding process to generate the floor geometry is presented, with a description of the fabrication process, the concrete mix design, material testing and experimental testing. The results from the serviceability and ultimate load testing of the prototype floor are documented in detail. The data showed that the floor unit was both stiff under service load, with maximum vertical deflections less than span/2500, as well as possessing sufficient strength for ultimate loading, carrying 2.5 times the factored design load in a more critical asymmetric loading scenario. A camera setup was used to measure displacements in-line with traditional displacement transducers, to give contour plots of vertical deflections., Peer Reviewed, Postprint (author's final draft)
- Published
- 2017
35. Mesoporous TiO2 Thin Film Formed From a Bioinspired Supramolecular Assembly
- Author
-
Wu, Yi-Chen, Lu, Y S, Bastakoti, Bishnu Prasad, Li, Yunqi, Pramanik, Malay, Hossain, Md Shahriar, Yanmaz, Ekrem, Kuo, Shiao-Wei, Wu, Yi-Chen, Lu, Y S, Bastakoti, Bishnu Prasad, Li, Yunqi, Pramanik, Malay, Hossain, Md Shahriar, Yanmaz, Ekrem, and Kuo, Shiao-Wei
- Published
- 2016
36. Dynamic magneto-optical imaging of superconducting thin films
- Author
-
Wells, Frederick, Pan, Alexey V, Wilson, Stephen, Golovchanskiy, Igor, Fedoseev, Sergey, Rosenfeld, Anatoly B, Wells, Frederick, Pan, Alexey V, Wilson, Stephen, Golovchanskiy, Igor, Fedoseev, Sergey, and Rosenfeld, Anatoly B
- Abstract
We present a novel method for analysis of superconducting thin films using dynamic magneto-optical imaging, revealing hallmarks of flux penetration with temporal resolution around 1 ms (in the present work) or better. This method involves investigation of transient field and dynamic current distributions, which are calculated by an inversion procedure on the Biot-Savart Law, which we show to be valid under dynamic conditions. We compare and discuss the flux front penetration speed and evolution of current distribution in high quality YBa2Cu3O${}_{7-\delta }$ thin films with that of samples deliberately damaged in such a way as to reduce critical current density without causing macroscopic damage.
- Published
- 2016
37. Stress in Thin Wall Structures Made by Layer Additive Manufacturing
- Author
-
Luzin, Vladimir, Hoye, Nicholas P, Luzin, Vladimir, and Hoye, Nicholas P
- Abstract
Manufacturing of thin wall structures is one of the main applications of additive manufacturing, where it has significant advantages over traditional milling and machining techniques or welded analogues. Such thin walled structures are common in structural aerospace components, and are also frequently made from titanium alloys. For such large-scale components, layer deposition strategy is more advantageous rather than a pixel-wise deposition approach due to the demand for high productivity and size requirements. Several techniques can be used to produce layer-wise build-ups, including laser-powered Direct Metal Deposition (DMD) process or gas tungsten arc welding (GTAW). Although, in the general case of arbitrary thin wall structures the stress distribution is complex, for some simple geometries, the stress state is simple and can be well characterized within a model by a single parameter representing a layer deposition stress in the steady-state regime. The model calculations were verified by experimental results on a thin-walled sample component that was manufactured from Ti-6Al-4V by GTAW with the residual stresses measured using KOWARI neutron strain scanner at the OPAL research reactor (ANSTO).
- Published
- 2016
38. Stress in Thin Wall Structures Made by Layer Additive Manufacturing
- Author
-
Luzin, Vladimir, Hoye, Nicholas P, Luzin, Vladimir, and Hoye, Nicholas P
- Abstract
Manufacturing of thin wall structures is one of the main applications of additive manufacturing, where it has significant advantages over traditional milling and machining techniques or welded analogues. Such thin walled structures are common in structural aerospace components, and are also frequently made from titanium alloys. For such large-scale components, layer deposition strategy is more advantageous rather than a pixel-wise deposition approach due to the demand for high productivity and size requirements. Several techniques can be used to produce layer-wise build-ups, including laser-powered Direct Metal Deposition (DMD) process or gas tungsten arc welding (GTAW). Although, in the general case of arbitrary thin wall structures the stress distribution is complex, for some simple geometries, the stress state is simple and can be well characterized within a model by a single parameter representing a layer deposition stress in the steady-state regime. The model calculations were verified by experimental results on a thin-walled sample component that was manufactured from Ti-6Al-4V by GTAW with the residual stresses measured using KOWARI neutron strain scanner at the OPAL research reactor (ANSTO).
- Published
- 2016
39. Mesoporous TiO2 Thin Film Formed From a Bioinspired Supramolecular Assembly
- Author
-
Wu, Yi-Chen, Lu, Y S, Bastakoti, Bishnu Prasad, Li, Yunqi, Pramanik, Malay, Hossain, Md Shahriar, Yanmaz, Ekrem, Kuo, Shiao-Wei, Wu, Yi-Chen, Lu, Y S, Bastakoti, Bishnu Prasad, Li, Yunqi, Pramanik, Malay, Hossain, Md Shahriar, Yanmaz, Ekrem, and Kuo, Shiao-Wei
- Published
- 2016
40. Dynamic magneto-optical imaging of superconducting thin films
- Author
-
Wells, Frederick, Pan, Alexey V, Wilson, Stephen, Golovchanskiy, Igor, Fedoseev, Sergey, Rosenfeld, Anatoly B, Wells, Frederick, Pan, Alexey V, Wilson, Stephen, Golovchanskiy, Igor, Fedoseev, Sergey, and Rosenfeld, Anatoly B
- Abstract
We present a novel method for analysis of superconducting thin films using dynamic magneto-optical imaging, revealing hallmarks of flux penetration with temporal resolution around 1 ms (in the present work) or better. This method involves investigation of transient field and dynamic current distributions, which are calculated by an inversion procedure on the Biot-Savart Law, which we show to be valid under dynamic conditions. We compare and discuss the flux front penetration speed and evolution of current distribution in high quality YBa2Cu3O${}_{7-\delta }$ thin films with that of samples deliberately damaged in such a way as to reduce critical current density without causing macroscopic damage.
- Published
- 2016
41. Stress in Thin Wall Structures Made by Layer Additive Manufacturing
- Author
-
Luzin, Vladimir, Hoye, Nicholas P, Luzin, Vladimir, and Hoye, Nicholas P
- Abstract
Manufacturing of thin wall structures is one of the main applications of additive manufacturing, where it has significant advantages over traditional milling and machining techniques or welded analogues. Such thin walled structures are common in structural aerospace components, and are also frequently made from titanium alloys. For such large-scale components, layer deposition strategy is more advantageous rather than a pixel-wise deposition approach due to the demand for high productivity and size requirements. Several techniques can be used to produce layer-wise build-ups, including laser-powered Direct Metal Deposition (DMD) process or gas tungsten arc welding (GTAW). Although, in the general case of arbitrary thin wall structures the stress distribution is complex, for some simple geometries, the stress state is simple and can be well characterized within a model by a single parameter representing a layer deposition stress in the steady-state regime. The model calculations were verified by experimental results on a thin-walled sample component that was manufactured from Ti-6Al-4V by GTAW with the residual stresses measured using KOWARI neutron strain scanner at the OPAL research reactor (ANSTO).
- Published
- 2016
42. Stress in Thin Wall Structures Made by Layer Additive Manufacturing
- Author
-
Luzin, Vladimir, Hoye, Nicholas P, Luzin, Vladimir, and Hoye, Nicholas P
- Abstract
Manufacturing of thin wall structures is one of the main applications of additive manufacturing, where it has significant advantages over traditional milling and machining techniques or welded analogues. Such thin walled structures are common in structural aerospace components, and are also frequently made from titanium alloys. For such large-scale components, layer deposition strategy is more advantageous rather than a pixel-wise deposition approach due to the demand for high productivity and size requirements. Several techniques can be used to produce layer-wise build-ups, including laser-powered Direct Metal Deposition (DMD) process or gas tungsten arc welding (GTAW). Although, in the general case of arbitrary thin wall structures the stress distribution is complex, for some simple geometries, the stress state is simple and can be well characterized within a model by a single parameter representing a layer deposition stress in the steady-state regime. The model calculations were verified by experimental results on a thin-walled sample component that was manufactured from Ti-6Al-4V by GTAW with the residual stresses measured using KOWARI neutron strain scanner at the OPAL research reactor (ANSTO).
- Published
- 2016
43. The dynamical look at the subsets of a group
- Author
-
Protasov, Igor V., Slobodianiuk, Serhii, Protasov, Igor V., and Slobodianiuk, Serhii
- Abstract
[EN] We consider the action of a group $G$ on the family $\mathcal{P}(G)$ of all subsets of $G$ by the right shifts $A\mapsto Ag$ and give the dynamical characterizations of thin, $n$-thin, sparse and scattered subsets.For $n\in\mathbb{N}$, a subset $A$ of a group $G$ is called $n$-thin if $g_0A\cap\dots\cap g_nA$ is finite for all distinct $g_0,\dots,g_n\in G$.Each $n$-thin subset of a group of cardinality $\aleph_0$ can be partitioned into $n$ $1$-thin subsets but there is a $2$-thin subset in some Abelian group of cardinality $\aleph_2$ which cannot be partitioned into two $1$-thin subsets. We eliminate the gap between $\aleph_0$ and $\aleph_2$ proving that each $n$-thin subset of an Abelian group of cardinality $\aleph_1$ can be partitioned into $n$ $1$-thin subsets.
- Published
- 2016
44. Aerogel as a Soft Acoustic Metamaterial for Airborne Sound
- Author
-
Universitat Politècnica de València. Escuela Técnica Superior de Ingenieros de Telecomunicación - Escola Tècnica Superior d'Enginyers de Telecomunicació, Universitat Politècnica de València. Departamento de Ingeniería Electrónica - Departament d'Enginyeria Electrònica, Ministerio de Economía y Competitividad, Office of Naval Research, Guild, Matthew, García Chocano, Víctor Manuel, Sánchez-Dehesa Moreno-Cid, José, Martin, Theodore P., Calvo, David C., Orris, Gregory J., Universitat Politècnica de València. Escuela Técnica Superior de Ingenieros de Telecomunicación - Escola Tècnica Superior d'Enginyers de Telecomunicació, Universitat Politècnica de València. Departamento de Ingeniería Electrónica - Departament d'Enginyeria Electrònica, Ministerio de Economía y Competitividad, Office of Naval Research, Guild, Matthew, García Chocano, Víctor Manuel, Sánchez-Dehesa Moreno-Cid, José, Martin, Theodore P., Calvo, David C., and Orris, Gregory J.
- Abstract
Soft acoustic metamaterials utilizing mesoporous structures have been proposed recently as a means for tuning the overall effective properties of the metamaterial and providing better coupling to the surrounding air. In this paper, the use of silica aerogel is examined theoretically and experimentally as part of a compact soft acoustic metamaterial structure, which enables a wide range of exotic effective macroscopic properties to be demonstrated, including negative density, density near zero, and nonresonant broadband slow-sound propagation. Experimental data are obtained on the effective density and sound speed using an air-filled acoustic impedance tube for flexural metamaterial elements, which have been investigated previously only indirectly due to the large contrast in acoustic impedance compared to that of air. Experimental results are presented for silica aerogel arranged in parallel with either one or two acoustic ports and are in very good agreement with the theoretical model.
- Published
- 2016
45. The dynamical look at the subsets of a group
- Author
-
Protasov, Igor V., Slobodianiuk, Serhii, Protasov, Igor V., and Slobodianiuk, Serhii
- Abstract
[EN] We consider the action of a group $G$ on the family $\mathcal{P}(G)$ of all subsets of $G$ by the right shifts $A\mapsto Ag$ and give the dynamical characterizations of thin, $n$-thin, sparse and scattered subsets.For $n\in\mathbb{N}$, a subset $A$ of a group $G$ is called $n$-thin if $g_0A\cap\dots\cap g_nA$ is finite for all distinct $g_0,\dots,g_n\in G$.Each $n$-thin subset of a group of cardinality $\aleph_0$ can be partitioned into $n$ $1$-thin subsets but there is a $2$-thin subset in some Abelian group of cardinality $\aleph_2$ which cannot be partitioned into two $1$-thin subsets. We eliminate the gap between $\aleph_0$ and $\aleph_2$ proving that each $n$-thin subset of an Abelian group of cardinality $\aleph_1$ can be partitioned into $n$ $1$-thin subsets.
- Published
- 2016
46. The dynamical look at the subsets of a group
- Author
-
Protasov, Igor V., Slobodianiuk, Serhii, Protasov, Igor V., and Slobodianiuk, Serhii
- Abstract
[EN] We consider the action of a group $G$ on the family $\mathcal{P}(G)$ of all subsets of $G$ by the right shifts $A\mapsto Ag$ and give the dynamical characterizations of thin, $n$-thin, sparse and scattered subsets.For $n\in\mathbb{N}$, a subset $A$ of a group $G$ is called $n$-thin if $g_0A\cap\dots\cap g_nA$ is finite for all distinct $g_0,\dots,g_n\in G$.Each $n$-thin subset of a group of cardinality $\aleph_0$ can be partitioned into $n$ $1$-thin subsets but there is a $2$-thin subset in some Abelian group of cardinality $\aleph_2$ which cannot be partitioned into two $1$-thin subsets. We eliminate the gap between $\aleph_0$ and $\aleph_2$ proving that each $n$-thin subset of an Abelian group of cardinality $\aleph_1$ can be partitioned into $n$ $1$-thin subsets.
- Published
- 2016
47. The dynamical look at the subsets of a group
- Author
-
Protasov, Igor V., Slobodianiuk, Serhii, Protasov, Igor V., and Slobodianiuk, Serhii
- Abstract
[EN] We consider the action of a group $G$ on the family $\mathcal{P}(G)$ of all subsets of $G$ by the right shifts $A\mapsto Ag$ and give the dynamical characterizations of thin, $n$-thin, sparse and scattered subsets.For $n\in\mathbb{N}$, a subset $A$ of a group $G$ is called $n$-thin if $g_0A\cap\dots\cap g_nA$ is finite for all distinct $g_0,\dots,g_n\in G$.Each $n$-thin subset of a group of cardinality $\aleph_0$ can be partitioned into $n$ $1$-thin subsets but there is a $2$-thin subset in some Abelian group of cardinality $\aleph_2$ which cannot be partitioned into two $1$-thin subsets. We eliminate the gap between $\aleph_0$ and $\aleph_2$ proving that each $n$-thin subset of an Abelian group of cardinality $\aleph_1$ can be partitioned into $n$ $1$-thin subsets.
- Published
- 2016
48. The dynamical look at the subsets of a group
- Author
-
Protasov, Igor V., Slobodianiuk, Serhii, Protasov, Igor V., and Slobodianiuk, Serhii
- Abstract
[EN] We consider the action of a group $G$ on the family $\mathcal{P}(G)$ of all subsets of $G$ by the right shifts $A\mapsto Ag$ and give the dynamical characterizations of thin, $n$-thin, sparse and scattered subsets.For $n\in\mathbb{N}$, a subset $A$ of a group $G$ is called $n$-thin if $g_0A\cap\dots\cap g_nA$ is finite for all distinct $g_0,\dots,g_n\in G$.Each $n$-thin subset of a group of cardinality $\aleph_0$ can be partitioned into $n$ $1$-thin subsets but there is a $2$-thin subset in some Abelian group of cardinality $\aleph_2$ which cannot be partitioned into two $1$-thin subsets. We eliminate the gap between $\aleph_0$ and $\aleph_2$ proving that each $n$-thin subset of an Abelian group of cardinality $\aleph_1$ can be partitioned into $n$ $1$-thin subsets.
- Published
- 2016
49. Tuning superconductivity in FeSe thin films via magnesium doping
- Author
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Qiu, Wenbin, Ma, Zongqing, Liu, Yongchang, Hossain, Md Shahriar, Wang, Xiaolin, Cai, Chuanbing, Dou, S X, Qiu, Wenbin, Ma, Zongqing, Liu, Yongchang, Hossain, Md Shahriar, Wang, Xiaolin, Cai, Chuanbing, and Dou, S X
- Abstract
In contrast to its bulk crystal, the FeSe thin film or layer exhibits better superconductivity performance, which recently attracted much interest in its fundamental research as well as in potential applications around the world. In the present work, tuning superconductivity in FeSe thin films was achieved by magnesium-doping technique. Tc is significantly enhanced from 10.7 K in pure FeSe films to 13.4 K in optimized Mg-doped ones, which is approximately 1.5 times higher than that of bulk crystals. This is the first time achieving the enhancement of superconducting transition temperature in FeSe thin films with practical thickness (120 nm) via a simple Mg-doping process. Moreover, these Mg-doped FeSe films are quite stable in atmosphere with Hc2 up to 32.7 T and Tc zero up to 12 K, respectively, implying their outstanding potential for practical applications in high magnetic fields. It was found that Mg enters the matrix of FeSe lattice, and does not react with FeSe forming any other secondary phase. Actually, Mg first occupies Fe-vacancies, and then substitutes for some Fe in the FeSe crystal lattices when Fe-vacancies are fully filled. Simultaneously, external Mg-doping introduces sufficient electron doping and induces the variation of electron carrier concentration according to Hall coefficient measurements. This is responsible for the evolution of superconducting performance in FeSe thin films. Our results provide a new strategy to improve the superconductivity of 11 type Fe-based superconductors and will help us to understand the intrinsic mechanism of this unconventional superconducting system.
- Published
- 2016
50. Mesoporous TiO2 Thin Film Formed From a Bioinspired Supramolecular Assembly
- Author
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Wu, Yi-Chen, Lu, Y S, Bastakoti, Bishnu Prasad, Li, Yunqi, Pramanik, Malay, Hossain, Md Shahriar, Yanmaz, Ekrem, Kuo, Shiao-Wei, Wu, Yi-Chen, Lu, Y S, Bastakoti, Bishnu Prasad, Li, Yunqi, Pramanik, Malay, Hossain, Md Shahriar, Yanmaz, Ekrem, and Kuo, Shiao-Wei
- Published
- 2016
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