Pub Date : 2016-03-23DOI: 10.1080/23311940.2016.1158342
L. Angermann, V. Yatsyk
Abstract The paper focuses on the development of a mathematical model, an effective algorithm and a self-consistent numerical analysis of the multifunctional properties of resonant scattering and generation of oscillations by nonlinear, cubically polarizable layered structures. The multifunctionality of such layered media is caused by the nonlinear mechanism between interacting oscillations—the incident oscillations (exciting the nonlinear layer from the upper and lower half-spaces) as well as the scattered and generated oscillations at the frequencies of excitation/scattering and generation. The study of the resonance properties of scattering and generation of oscillations by a nonlinear structure with a controllable permittivity in dependence on the variation of the intensities of the components of the exciting wave package is of particular interest. In the present paper, we extend our former results, and furthermore we analyze the realizability of multifunctional properties of nonlinear electromagnetic objects with a controllable permittivity. The results of our investigations (i) demonstrate the possibility to control the scattering and generation properties of the nonlinear structure via the intensity of the incident field, (ii) indicate the possibility of increasing the multifunctionality of electronic devices, of designing frequency multipliers, and other electrodynamic devices containing nonlinear dielectrics with controllable permittivity.
{"title":"The multifunctional process of resonance scattering and generation of oscillations by nonlinear layered structures","authors":"L. Angermann, V. Yatsyk","doi":"10.1080/23311940.2016.1158342","DOIUrl":"https://doi.org/10.1080/23311940.2016.1158342","url":null,"abstract":"Abstract The paper focuses on the development of a mathematical model, an effective algorithm and a self-consistent numerical analysis of the multifunctional properties of resonant scattering and generation of oscillations by nonlinear, cubically polarizable layered structures. The multifunctionality of such layered media is caused by the nonlinear mechanism between interacting oscillations—the incident oscillations (exciting the nonlinear layer from the upper and lower half-spaces) as well as the scattered and generated oscillations at the frequencies of excitation/scattering and generation. The study of the resonance properties of scattering and generation of oscillations by a nonlinear structure with a controllable permittivity in dependence on the variation of the intensities of the components of the exciting wave package is of particular interest. In the present paper, we extend our former results, and furthermore we analyze the realizability of multifunctional properties of nonlinear electromagnetic objects with a controllable permittivity. The results of our investigations (i) demonstrate the possibility to control the scattering and generation properties of the nonlinear structure via the intensity of the incident field, (ii) indicate the possibility of increasing the multifunctionality of electronic devices, of designing frequency multipliers, and other electrodynamic devices containing nonlinear dielectrics with controllable permittivity.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1158342","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60085024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-03-02DOI: 10.1080/23311940.2016.1150408
Victor Hernandez-Urbina, J. M. Herrmann, Bernardo Spagnolo, M. Herrmann
Abstract Brain networks are neither regular nor random. Their structure allows for optimal information processing and transmission across the entire neural substrate of an organism. However, for topological features to be appropriately harnessed, brain networks should implement a dynamical regime which prevents phase-locked and chaotic behaviour. Critical neural dynamics refer to a dynamical regime in which the system is poised at the boundary between regularity and randomness. It has been reported that neural systems poised at this boundary achieve maximum computational power. In this paper, we review recent results regarding critical neural dynamics that emerge from systems whose underlying structure exhibits complex network properties.
{"title":"Neuronal avalanches in complex networks","authors":"Victor Hernandez-Urbina, J. M. Herrmann, Bernardo Spagnolo, M. Herrmann","doi":"10.1080/23311940.2016.1150408","DOIUrl":"https://doi.org/10.1080/23311940.2016.1150408","url":null,"abstract":"Abstract Brain networks are neither regular nor random. Their structure allows for optimal information processing and transmission across the entire neural substrate of an organism. However, for topological features to be appropriately harnessed, brain networks should implement a dynamical regime which prevents phase-locked and chaotic behaviour. Critical neural dynamics refer to a dynamical regime in which the system is poised at the boundary between regularity and randomness. It has been reported that neural systems poised at this boundary achieve maximum computational power. In this paper, we review recent results regarding critical neural dynamics that emerge from systems whose underlying structure exhibits complex network properties.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1150408","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-02-17DOI: 10.1080/23311940.2016.1156281
Y. Mizuguchi, A. Nishida, A. Omachi, O. Miura
Abstract The layered Bi-chalcogenide compounds have been drawing much attention as a new layered superconductor family since 2012. Due to the rich variation of crystal structure and constituent elements, the development of new physics and chemistry of the layered Bi-chalcogenide family and its applications as functional materials have been expected. Recently, it was revealed that the layered Bi chalcogenides can show a relatively high thermoelectric performance (ZT = 0.36 in LaOBiSSe at ~650 K). Here, we show the crystal structure variation of the Bi-chalcogenide family and their thermoelectric properties. Finally, the possible strategies for enhancing the thermoelectric performance are discussed on the basis of the experimental and the theoretical facts reviewed here.
{"title":"Thermoelectric properties of new Bi-chalcogenide layered compounds","authors":"Y. Mizuguchi, A. Nishida, A. Omachi, O. Miura","doi":"10.1080/23311940.2016.1156281","DOIUrl":"https://doi.org/10.1080/23311940.2016.1156281","url":null,"abstract":"Abstract The layered Bi-chalcogenide compounds have been drawing much attention as a new layered superconductor family since 2012. Due to the rich variation of crystal structure and constituent elements, the development of new physics and chemistry of the layered Bi-chalcogenide family and its applications as functional materials have been expected. Recently, it was revealed that the layered Bi chalcogenides can show a relatively high thermoelectric performance (ZT = 0.36 in LaOBiSSe at ~650 K). Here, we show the crystal structure variation of the Bi-chalcogenide family and their thermoelectric properties. Finally, the possible strategies for enhancing the thermoelectric performance are discussed on the basis of the experimental and the theoretical facts reviewed here.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1156281","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-02-17DOI: 10.1080/23311940.2016.1142819
K. F. Tamrin, B. Rahmatullah
Abstract Understanding three-dimensional (3D) fluid flow behaviour is undeniably crucial in improving performance and efficiency in a wide range of applications in engineering and medical fields. Holographic particle image velocimetry (HPIV) is a potential tool to probe and characterize complex flow dynamics since it is a truly three-dimensional three-component measurement technique. The technique relies on the coherent light scattered by small seeding particles that are assumed to faithfully follow the flow for subsequent reconstruction of the same the event afterward. However, extraction of useful 3D displacement data from these particle images is usually aggravated by noise and aberration which are inherent within the optical system. Noise and aberration have been considered as major hurdles in HPIV in obtaining accurate particle image identification and its corresponding 3D position. Major contributions to noise include zero-order diffraction, out-of-focus particles, virtual image and emulsion grain scattering. Noise suppression is crucial to ensure that particle image can be distinctly differentiated from background noise while aberration compensation forms particle image with high integrity. This paper reviews a number of HPIV configurations that have been proposed to address these issues, summarizes the key findings and outlines a basis for follow-on research.
{"title":"A review on noise suppression and aberration compensation in holographic particle image velocimetry","authors":"K. F. Tamrin, B. Rahmatullah","doi":"10.1080/23311940.2016.1142819","DOIUrl":"https://doi.org/10.1080/23311940.2016.1142819","url":null,"abstract":"Abstract Understanding three-dimensional (3D) fluid flow behaviour is undeniably crucial in improving performance and efficiency in a wide range of applications in engineering and medical fields. Holographic particle image velocimetry (HPIV) is a potential tool to probe and characterize complex flow dynamics since it is a truly three-dimensional three-component measurement technique. The technique relies on the coherent light scattered by small seeding particles that are assumed to faithfully follow the flow for subsequent reconstruction of the same the event afterward. However, extraction of useful 3D displacement data from these particle images is usually aggravated by noise and aberration which are inherent within the optical system. Noise and aberration have been considered as major hurdles in HPIV in obtaining accurate particle image identification and its corresponding 3D position. Major contributions to noise include zero-order diffraction, out-of-focus particles, virtual image and emulsion grain scattering. Noise suppression is crucial to ensure that particle image can be distinctly differentiated from background noise while aberration compensation forms particle image with high integrity. This paper reviews a number of HPIV configurations that have been proposed to address these issues, summarizes the key findings and outlines a basis for follow-on research.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1142819","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-02-01DOI: 10.1080/23311940.2015.1133481
Abu Zayed Mohammad Saliqur Rahman, Xingzhong Cao, Baoyi Wang, J. Evslin, Qiu Xu, K. Atobe
We investigated neutron-irradiation-induced point defects in spinel single crystals using a synchrotron VUV-UV source and positron lifetime spectroscopy. Photoexcitation (PE) spectra near 230 nm and their corresponding photoluminescence (PL) spectra at 475 nm were attributed to F-centers. With increasing irradiation temperature and fluence, PE efficiency and PL intensity decreased dramatically. Positron lifetimes (PLT) of neutron-irradiated and non-irradiated samples were measured to identify the cation vacancies. A PLT measurement of 250 ps was obtained in a neutron-irradiated (20 K) sample which is tentatively attributed to an aluminum monovacancy. Decreasing PLT with higher irradiation indicates the formation of oxygen-vacancy complex centers.
{"title":"Synchrotron VUV-UV and positron lifetime spectroscopy study of vacancy-type defects in reactor neutron-irradiated MgO·nAl2O3 (n = 2)","authors":"Abu Zayed Mohammad Saliqur Rahman, Xingzhong Cao, Baoyi Wang, J. Evslin, Qiu Xu, K. Atobe","doi":"10.1080/23311940.2015.1133481","DOIUrl":"https://doi.org/10.1080/23311940.2015.1133481","url":null,"abstract":"We investigated neutron-irradiation-induced point defects in spinel single crystals using a synchrotron VUV-UV source and positron lifetime spectroscopy. Photoexcitation (PE) spectra near 230 nm and their corresponding photoluminescence (PL) spectra at 475 nm were attributed to F-centers. With increasing irradiation temperature and fluence, PE efficiency and PL intensity decreased dramatically. Positron lifetimes (PLT) of neutron-irradiated and non-irradiated samples were measured to identify the cation vacancies. A PLT measurement of 250 ps was obtained in a neutron-irradiated (20 K) sample which is tentatively attributed to an aluminum monovacancy. Decreasing PLT with higher irradiation indicates the formation of oxygen-vacancy complex centers.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1133481","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-28DOI: 10.1080/23311940.2015.1134263
P. Panchadhyayee, Nityananda Das
Abstract We have simulated the similar features of the well-known classical phenomena in quantum domain under the formalism of probability amplitude method. The identical pattern of interference fringes of a Fabry–Perot interferometer (especially on reflection mode) is obtained through the power-broadened spectral line shape of the population distribution in the excited state with careful delineation of a coherently driven two-level atomic model. In a unit wavelength domain, such pattern can be substantially modified by controlling typical spatial field arrangement in one and two dimensions, which is found complementary to the findings of recent research on atom localization in sub-wavelength domain. The spatial dependence of temporal dynamics has also been studied at a particular condition, which is equivalent to that could be obtained under Raman–Nath diffraction controlled by spatial phase.
{"title":"Classical analogues of a quantum system in spatial and temporal domains: A probability amplitude approach","authors":"P. Panchadhyayee, Nityananda Das","doi":"10.1080/23311940.2015.1134263","DOIUrl":"https://doi.org/10.1080/23311940.2015.1134263","url":null,"abstract":"Abstract We have simulated the similar features of the well-known classical phenomena in quantum domain under the formalism of probability amplitude method. The identical pattern of interference fringes of a Fabry–Perot interferometer (especially on reflection mode) is obtained through the power-broadened spectral line shape of the population distribution in the excited state with careful delineation of a coherently driven two-level atomic model. In a unit wavelength domain, such pattern can be substantially modified by controlling typical spatial field arrangement in one and two dimensions, which is found complementary to the findings of recent research on atom localization in sub-wavelength domain. The spatial dependence of temporal dynamics has also been studied at a particular condition, which is equivalent to that could be obtained under Raman–Nath diffraction controlled by spatial phase.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1134263","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-31DOI: 10.1080/23311940.2015.1064575
A. Arbey, F. Mahmoudi
The Minimal Supersymmetric extension of the Standard Model (MSSM) provides suitable candidates for cold dark matter. We discuss here the constraints from dark matter direct detection and cosmological dark matter density, as well as LHC data from Higgs, SUSY and monojet searches, and flavour physics data, in the context of the phenomenological MSSM (pMSSM) with neutralino dark matter. We show that the complementarity of the different sectors is essential to probe the pMSSM parameter space.
{"title":"Interplay of LHC and dark matter searches in the MSSM","authors":"A. Arbey, F. Mahmoudi","doi":"10.1080/23311940.2015.1064575","DOIUrl":"https://doi.org/10.1080/23311940.2015.1064575","url":null,"abstract":"The Minimal Supersymmetric extension of the Standard Model (MSSM) provides suitable candidates for cold dark matter. We discuss here the constraints from dark matter direct detection and cosmological dark matter density, as well as LHC data from Higgs, SUSY and monojet searches, and flavour physics data, in the context of the phenomenological MSSM (pMSSM) with neutralino dark matter. We show that the complementarity of the different sectors is essential to probe the pMSSM parameter space.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1064575","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-31DOI: 10.1080/23311940.2015.1083285
K. Vieira
On the 23 July 2015, NASA announced the discovery of Kepler-452b, the first exoplanet similar in size to our own planet (about 60% larger than Earth), orbiting around a star similar to our Sun (Kepler 452 is a G2V-type star) at about the same distance between Earth and Sun, within the habitable zone of this star. From these, other similarities extend: this exoplanet takes 385 Earth days to orbit its star, its probable mass is calculated to be about five times that of the Earth, and its surface gravity is twice of Earth’s.
{"title":"Finding earths","authors":"K. Vieira","doi":"10.1080/23311940.2015.1083285","DOIUrl":"https://doi.org/10.1080/23311940.2015.1083285","url":null,"abstract":"On the 23 July 2015, NASA announced the discovery of Kepler-452b, the first exoplanet similar in size to our own planet (about 60% larger than Earth), orbiting around a star similar to our Sun (Kepler 452 is a G2V-type star) at about the same distance between Earth and Sun, within the habitable zone of this star. From these, other similarities extend: this exoplanet takes 385 Earth days to orbit its star, its probable mass is calculated to be about five times that of the Earth, and its surface gravity is twice of Earth’s.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1083285","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-31DOI: 10.1080/23311940.2015.1062216
Catarina Espírito Santo
Recent progress in the field of ultra-high energy cosmic rays has been driven by the data collected by the Pierre Auger Observatory in the southern hemisphere, and also by the Telescope Array in the northern hemisphere. These hybrid observatories combine large ground arrays with fluorescence detection techniques. In this paper, selected results will be reviewed. Future challenges and prospects will be briefly addressed.
{"title":"Ultra-high energy cosmic rays: Present and future","authors":"Catarina Espírito Santo","doi":"10.1080/23311940.2015.1062216","DOIUrl":"https://doi.org/10.1080/23311940.2015.1062216","url":null,"abstract":"Recent progress in the field of ultra-high energy cosmic rays has been driven by the data collected by the Pierre Auger Observatory in the southern hemisphere, and also by the Telescope Array in the northern hemisphere. These hybrid observatories combine large ground arrays with fluorescence detection techniques. In this paper, selected results will be reviewed. Future challenges and prospects will be briefly addressed.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1062216","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-12-21DOI: 10.1080/23311940.2015.1123595
P. Dawar, N. S. Raghava, A. De
Abstract A new type of metamaterial-inspired patch antenna designed for having multi-resonance and minituarization has been elucidated. A novel metamaterial formed by combining 2 segment labyrinth and capacitive loaded strip has been designed by combining negative permeability and negative permittivity characteristics respectively, to form a Double Negative Group metamaterial. By adding 4 unit cells to the microstrip patch antenna resonating at 30 GHz, secondary resonances have been created around 8.5, 17.7, 20 and 23.7 GHz. Seventy-two per cent miniaturization of the structure is obtained using metamaterial-inspired antenna, but at the cost of reduction in bandwidth.
{"title":"A novel metamaterial for miniaturization and multi-resonance in antenna","authors":"P. Dawar, N. S. Raghava, A. De","doi":"10.1080/23311940.2015.1123595","DOIUrl":"https://doi.org/10.1080/23311940.2015.1123595","url":null,"abstract":"Abstract A new type of metamaterial-inspired patch antenna designed for having multi-resonance and minituarization has been elucidated. A novel metamaterial formed by combining 2 segment labyrinth and capacitive loaded strip has been designed by combining negative permeability and negative permittivity characteristics respectively, to form a Double Negative Group metamaterial. By adding 4 unit cells to the microstrip patch antenna resonating at 30 GHz, secondary resonances have been created around 8.5, 17.7, 20 and 23.7 GHz. Seventy-two per cent miniaturization of the structure is obtained using metamaterial-inspired antenna, but at the cost of reduction in bandwidth.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1123595","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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