Pub Date : 2023-12-20DOI: 10.1088/2399-6528/ad1762
Wanvisa Thengthong, S. Sakkaravej, Wiwat Wongkokua, C. Saiyasombat, N. Monarumit
The blue color of sapphire is commonly related to the amount of Fe and Ti impurities replacing Al3+ in Al2O3 structure. Generally, the color intensity on sapphires is related to the gem deposits including the basaltic-related and metamorphic-related ones. The color of sapphires has been changed after heating under oxidizing atmosphere. However, the explanation about the color mechanism from some previous research contradicted each other and it was still wondered. For this reason, this research is focused on the role of Fe and Ti oxidation states as well as the blue color mechanism on sapphires before and after heating under oxidizing atmosphere. In this study, the sapphire samples were collected from different gem deposits including basaltic-related sapphires from Kanchanaburi province, Thailand and metamorphic-related ones from Sri Lanka before and after heating at 1100°C under oxidizing atmosphere. As a result, the blue color on sapphires before heating can be described that a hole color center assigned to Fe3+-Ti4+ mixed acceptor states inside an energy band gap that could be received an electron from the valence band for charge-balancing after excitation. After heating, the basaltic-related sapphires turned from dark blue to light blue and the metamorphic-related ones turned from light blue to colorless because the Fe3+-Ti4+ mixed acceptor states were decreased because a hole color center was filled by an electron from oxygen during the heating process instead of an electron from the valence band. Therefore, it can be concluded that the blue color mechanism on sapphires before and after heating under oxidizing atmosphere can be explained by an energy band model involving the presence or absence of Fe3+-Ti4+ mixed acceptor states as well as a hole color center inside an energy band gap.
蓝宝石的蓝色通常与取代 Al2O3 结构中 Al3+ 的 Fe 和 Ti 杂质的含量有关。一般来说，蓝宝石的颜色强度与宝石矿床有关，包括玄武岩相关矿床和变质岩相关矿床。在氧化气氛下加热后，蓝宝石的颜色会发生变化。然而，之前的一些研究对颜色机理的解释相互矛盾，仍然令人疑惑。因此，本研究将重点放在氧化气氛下加热前后，Fe 和 Ti 氧化态的作用以及蓝宝石的蓝色机理上。在这项研究中，蓝宝石样品采集自不同的宝石矿床，包括泰国堪差那武里府的玄武岩相关蓝宝石和斯里兰卡的变质岩相关蓝宝石。因此，加热前蓝宝石上的蓝色可以描述为能带间隙内 Fe3+-Ti4+ 混合受体态的空穴色心，激发后可从价带获得电子以平衡电荷。加热后，玄武岩相关蓝宝石由深蓝色变为浅蓝色，而变质岩相关蓝宝石则由浅蓝色变为无色，这是因为在加热过程中，空穴色心被来自氧的电子填满，而不是被来自价带的电子填满，从而导致Fe3+-Ti4+混合受主态减少。因此，可以得出结论，在氧化气氛下加热前后蓝宝石的蓝色机理可以用能带模型来解释，该模型涉及能带间隙内是否存在 Fe3+-Ti4+ 混合受主态以及空穴色心。
{"title":"The blue color mechanism on sapphires from different gem deposits before and after heating under oxidizing atmosphere","authors":"Wanvisa Thengthong, S. Sakkaravej, Wiwat Wongkokua, C. Saiyasombat, N. Monarumit","doi":"10.1088/2399-6528/ad1762","DOIUrl":"https://doi.org/10.1088/2399-6528/ad1762","url":null,"abstract":"\u0000 The blue color of sapphire is commonly related to the amount of Fe and Ti impurities replacing Al3+ in Al2O3 structure. Generally, the color intensity on sapphires is related to the gem deposits including the basaltic-related and metamorphic-related ones. The color of sapphires has been changed after heating under oxidizing atmosphere. However, the explanation about the color mechanism from some previous research contradicted each other and it was still wondered. For this reason, this research is focused on the role of Fe and Ti oxidation states as well as the blue color mechanism on sapphires before and after heating under oxidizing atmosphere. In this study, the sapphire samples were collected from different gem deposits including basaltic-related sapphires from Kanchanaburi province, Thailand and metamorphic-related ones from Sri Lanka before and after heating at 1100°C under oxidizing atmosphere. As a result, the blue color on sapphires before heating can be described that a hole color center assigned to Fe3+-Ti4+ mixed acceptor states inside an energy band gap that could be received an electron from the valence band for charge-balancing after excitation. After heating, the basaltic-related sapphires turned from dark blue to light blue and the metamorphic-related ones turned from light blue to colorless because the Fe3+-Ti4+ mixed acceptor states were decreased because a hole color center was filled by an electron from oxygen during the heating process instead of an electron from the valence band. Therefore, it can be concluded that the blue color mechanism on sapphires before and after heating under oxidizing atmosphere can be explained by an energy band model involving the presence or absence of Fe3+-Ti4+ mixed acceptor states as well as a hole color center inside an energy band gap.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":"51 22","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138955441","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 : 2023-12-13DOI: 10.1088/2399-6528/ad1049
R F Álvarez-Estrada, I Pastor, L Roso, F Castejón
Motivated by the renewed interest due to the presently available extreme light sources, the dynamics of a single classical relativistic (spinless) extended electron interacting with a classical electromagnetic field (an incoming radiation and the field radiated by the electron) is revisited. The field is treated in Lorentz gauge, with the Lorentz condition. By assumption, there is a crucial finite cut-off kmax on the magnitude of any wavevector contributing to the field (preventing a point electron) and, for a simple formulation, the initial conditions for particle and fields are given in the infinitely remote past. In an infinite three-dimensional vacuum and in an inertial system, Hamilton’s dynamical equations for the particle and the complex field amplitudes acting as canonical variables (a's) yield an exact Lorentz force equation for the former, that includes the incoming radiation and an exact radiation reaction force FRR due to the field radiated by the electron. Uniform motion is obtained as a test of consistency. Based upon numerical computations, some approximations on FRR are given. A covariant formulation is also presented.
{"title":"Classical relativistic electron-field dynamics: Hamiltonian approach to radiation reaction","authors":"R F Álvarez-Estrada, I Pastor, L Roso, F Castejón","doi":"10.1088/2399-6528/ad1049","DOIUrl":"https://doi.org/10.1088/2399-6528/ad1049","url":null,"abstract":"Motivated by the renewed interest due to the presently available extreme light sources, the dynamics of a single classical relativistic (spinless) extended electron interacting with a classical electromagnetic field (an incoming radiation and the field radiated by the electron) is revisited. The field is treated in Lorentz gauge, with the Lorentz condition. By assumption, there is a crucial finite cut-off <italic toggle=\"yes\">k</italic>\u0000<sub>max</sub> on the magnitude of any wavevector contributing to the field (preventing a point electron) and, for a simple formulation, the initial conditions for particle and fields are given in the infinitely remote past. In an infinite three-dimensional vacuum and in an inertial system, Hamilton’s dynamical equations for the particle and the complex field amplitudes acting as canonical variables (<italic toggle=\"yes\">a</italic>'s) yield an exact Lorentz force equation for the former, that includes the incoming radiation and an exact radiation reaction force <bold>F</bold>\u0000<sub>\u0000<italic toggle=\"yes\">RR</italic>\u0000</sub> due to the field radiated by the electron. Uniform motion is obtained as a test of consistency. Based upon numerical computations, some approximations on <bold>F</bold>\u0000<sub>\u0000<italic toggle=\"yes\">RR</italic>\u0000</sub> are given. A covariant formulation is also presented.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":"9 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138686827","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 : 2023-11-02DOI: 10.1088/2399-6528/ad08cf
Matteo Luca Ruggiero, Davide Astesiano
Abstract Gravitoelectromagnetic analogies are somewhat ubiquitous in General Relativity, and they are often used to explain peculiar effects of Einstein's theory of gravity in terms of familiar results from classical electromagnetism. Perhaps, the best known of these analogy pertains to the similarity between the equations of electromagnetism and those of the linearized theory of General Relativity. But the analogy is somewhat deeper and ultimately rooted in the splitting of spacetime, which is preliminary to the definition of the measurement process in General Relativity.
In this paper we review the various approaches that lead to the introduction of a magnetic-like part of the gravitational interaction, briefly called textit{gravitomagnetic} and, then, we provide a survey of the recent developments both from the theoretical and experimental viewpoints.
{"title":"A tale of analogies: a review on gravitomagnetic effects, rotating sources, observers and all that","authors":"Matteo Luca Ruggiero, Davide Astesiano","doi":"10.1088/2399-6528/ad08cf","DOIUrl":"https://doi.org/10.1088/2399-6528/ad08cf","url":null,"abstract":"Abstract Gravitoelectromagnetic analogies are somewhat ubiquitous in General Relativity, and they are often used to explain peculiar effects of Einstein's theory of gravity in terms of familiar results from classical electromagnetism. Perhaps, the best known of these analogy pertains to the similarity between the equations of electromagnetism and those of the linearized theory of General Relativity. But the analogy is somewhat deeper and ultimately rooted in the splitting of spacetime, which is preliminary to the definition of the measurement process in General Relativity.&#xD;In this paper we review the various approaches that lead to the introduction of a magnetic-like part of the gravitational interaction, briefly called textit{gravitomagnetic} and, then, we provide a survey of the recent developments both from the theoretical and experimental viewpoints.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":"14 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135875761","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 : 2023-10-24DOI: 10.1088/2399-6528/ad0649
Nagabhushana Prabhu
Abstract We present a new regularization procedure called autoregularization.
The new procedure regularizes the divergences, encountered previously 
in a scattering process, using the intrinsic scale of the process. We use 
autoregularization to calculate the amplitudes of several scattering processes 
in QED and compare the calculations with experimental measurements over a 
broad range of center-of-momentum energies (~ MeV to > 200 GeV). The 
calculated amplitudes are found to be in good agreement with experimental data. 
To test autoregularization in a non-Abelian gauge theory, we calculate the 
QCD coupling constant at 1-loop and show that, like the known regularization
schemes, autoregularization also predicts asymptotic freedom in QCD.
Finally, we show that the vacuum energy density of the free fields in the 
Standard Model, calculated using autoregularization, is smaller than the
current estimate of the cosmic critical density.
{"title":"A new method that automatically regularizes scattering amplitudes","authors":"Nagabhushana Prabhu","doi":"10.1088/2399-6528/ad0649","DOIUrl":"https://doi.org/10.1088/2399-6528/ad0649","url":null,"abstract":"Abstract We present a new regularization procedure called autoregularization.&#xD;The new procedure regularizes the divergences, encountered previously &#xD;in a scattering process, using the intrinsic scale of the process. We use &#xD;autoregularization to calculate the amplitudes of several scattering processes &#xD;in QED and compare the calculations with experimental measurements over a &#xD;broad range of center-of-momentum energies (~ MeV to > 200 GeV). The &#xD;calculated amplitudes are found to be in good agreement with experimental data. &#xD;To test autoregularization in a non-Abelian gauge theory, we calculate the &#xD;QCD coupling constant at 1-loop and show that, like the known regularization&#xD;schemes, autoregularization also predicts asymptotic freedom in QCD.&#xD;Finally, we show that the vacuum energy density of the free fields in the &#xD;Standard Model, calculated using autoregularization, is smaller than the&#xD;current estimate of the cosmic critical density.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":"55 11-12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135265961","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 : 2023-10-13DOI: 10.1088/2399-6528/ad035a
Sanjay Kumar Sah, Ishwar Koirala
Abstract The activities of Sn in the liquid solder ternary alloy Sn-Au-Cu at 900 K have been computed using the molecular interaction volume model (MIVM). The calculated values have been compared with the experimental data for three cross-sections, i.e., for three different ratios of aurum to copper (XAu:XCu) = 3:1, 1:1, and 1:3. In addition, the excess Gibbs free energy of mixing, ΔGEx, for these ternary liquid alloys has been determined using the same model parameters to assess their validity. The resulting values have then been compared with the corresponding experimental data found in the literature. The agreement between the theoretical and experimental results has been found to be satisfactory.
摘要:采用分子相互作用体积模型(MIVM)计算了锡在液态钎料三元合金Sn- au - cu中900 K时的活度。将计算值与实验数据进行了对比，即在三种不同的金铜比(XAu:XCu) = 3:1、1:1和1:3的情况下。此外，用相同的模型参数测定了这些三元液态合金的过量混合吉布斯自由能ΔGEx，以评估其有效性。然后将所得值与文献中相应的实验数据进行比较。理论与实验结果吻合较好。
{"title":"Computational assessment of Sn activities and integral excess free energy change for mixing in the Sn-Au-Cu ternary liquid alloys using the molecular interaction volume model","authors":"Sanjay Kumar Sah, Ishwar Koirala","doi":"10.1088/2399-6528/ad035a","DOIUrl":"https://doi.org/10.1088/2399-6528/ad035a","url":null,"abstract":"Abstract The activities of Sn in the liquid solder ternary alloy Sn-Au-Cu at 900 K have been computed using the molecular interaction volume model (MIVM). The calculated values have been compared with the experimental data for three cross-sections, i.e., for three different ratios of aurum to copper (XAu:XCu) = 3:1, 1:1, and 1:3. In addition, the excess Gibbs free energy of mixing, ΔGEx, for these ternary liquid alloys has been determined using the same model parameters to assess their validity. The resulting values have then been compared with the corresponding experimental data found in the literature. The agreement between the theoretical and experimental results has been found to be satisfactory.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135855437","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 : 2023-10-05DOI: 10.1088/2399-6528/ad0090
Andrew Wutke
Abstract This study exploits a historical gap in the evolution of metric systems that resulted from incomplete implementation of the “rationalization” concept published by Heaviside in 1893 and ignoring the suggestion of Maxwell in 1873 to use the simplest form of Newton’s gravitational law expression with no proportionality constant. Bridging this gap required deriving an experimental Rationalized Metric System (RMS) and a corresponding Universal Planck Natural Unit System (UPNUS) in [ LT ] units.The described solution combines Heaviside’s rationalization of Newton’s law and makes the unit of mass dimensions [L 3 T −2 ], as suggested by Maxwell. Consequently the modified Coulomb’s law, changes the unit of the electric charges to the same dimensions as those of the mass. The elimination of the kilogram and ampere has a disentangling effect on the dependencies among the constants of nature and opens new horizons. The new systems have the potential to become powerful exploratory tools in fundamental research and education because of the simplification of the relationships among physical quantities. Noteworthy highlights from analyzed examples include the following: The well-known expression for Stoney mass ( m S ) when converted to RMS units is reduced to the electron charge quantity, whereas traditional metric systems entangle the charge, speed of light, and gravitational constant, forming an entity in the dimension of mass, as first presented by Stoney in 1874. A well-substantiated conjecture is proposed, wherein the Stoney energy E S =m S c 2 is nothing but the long-sought, finite electric field energy of the electron, and the gravitational constant appears to be the limiting factor. In UPNUS, the most disentangled fundamental expression, apart from the Stoney mass, is the elementary charge ӗ as the function of the fine structure constant α and the Planck mass( m̆ P ̌): ӗ = m̆ P √α ≈1.073 476 with ӗ , m̆ P of [L 3 T −2 ] dimensions in Planck units, and m̆ P = 4π
摘要:本研究利用了公制系统发展的历史空白，这一空白是由于对Heaviside在1893年发表的“合理化”概念的不完全实现，以及忽视了麦克斯韦在1873年提出的使用牛顿万有引力定律最简单形式的无比例常数表达式的建议。弥合这一差距需要推导出一个实验性的合理化公制(RMS)和相应的[LT]单位普朗克自然单位制(UPNUS)。所描述的解结合了Heaviside对牛顿定律的合理化，并使质量维度的单位[L 3 T−2]，正如麦克斯韦所建议的那样。因此，修正后的库仑定律将电荷的单位改为与质量的单位相同的尺寸。千克和安培的消除对自然界常数之间的依赖关系产生了解缠作用，并开辟了新的视野。由于简化了物理量之间的关系，新系统有可能成为基础研究和教育中强大的探索工具。从分析的例子中，值得注意的亮点包括:众所周知的斯通质量(m S)在转换为均方根单位时被简化为电子电荷量，而传统的公制系统将电荷、光速和引力常数纠缠在一起，形成一个质量维度的实体，这是斯通在1874年首次提出的。提出了一个充分证实的猜想，其中斯通能E S =m S c 2只不过是长期寻找的有限电子电场能量，而引力常数似乎是限制因素。在UPNUS中，除Stoney质量外，最解离的基本表达式是基本电荷δ作为精细结构常数α和普朗克质量(m > P _)的函数:δ = m > P√α≈1.073 476，其中δ， m > P为[L 3 T−2]普朗克单位，m > P = 4π
{"title":"From newton to universal planck natural units – disentangling the constants of nature","authors":"Andrew Wutke","doi":"10.1088/2399-6528/ad0090","DOIUrl":"https://doi.org/10.1088/2399-6528/ad0090","url":null,"abstract":"Abstract This study exploits a historical gap in the evolution of metric systems that resulted from incomplete implementation of the “rationalization” concept published by Heaviside in 1893 and ignoring the suggestion of Maxwell in 1873 to use the simplest form of Newton’s gravitational law expression with no proportionality constant. Bridging this gap required deriving an experimental Rationalized Metric System (RMS) and a corresponding Universal Planck Natural Unit System (UPNUS) in [ LT ] units.The described solution combines Heaviside’s rationalization of Newton’s law and makes the unit of mass dimensions [L 3 T −2 ], as suggested by Maxwell. Consequently the modified Coulomb’s law, changes the unit of the electric charges to the same dimensions as those of the mass. The elimination of the kilogram and ampere has a disentangling effect on the dependencies among the constants of nature and opens new horizons. The new systems have the potential to become powerful exploratory tools in fundamental research and education because of the simplification of the relationships among physical quantities. Noteworthy highlights from analyzed examples include the following: The well-known expression for Stoney mass ( m S ) when converted to RMS units is reduced to the electron charge quantity, whereas traditional metric systems entangle the charge, speed of light, and gravitational constant, forming an entity in the dimension of mass, as first presented by Stoney in 1874. A well-substantiated conjecture is proposed, wherein the Stoney energy E S =m S c 2 is nothing but the long-sought, finite electric field energy of the electron, and the gravitational constant appears to be the limiting factor. In UPNUS, the most disentangled fundamental expression, apart from the Stoney mass, is the elementary charge ӗ as the function of the fine structure constant α and the Planck mass( m̆ P ̌): ӗ = m̆ P √α ≈1.073 476 with ӗ , m̆ P of [L 3 T −2 ] dimensions in Planck units, and m̆ P = 4π","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483931","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 : 2023-09-01DOI: 10.1088/2399-6528/ad0197
Nrushingh Charan Mahapatra, Prachet Bhuyan
Abstract The use of brain-computer interfaces to produce imagined speech from brain waves has the potential to assist individuals with difficulty producing speech or communicating silently. The decoding of covert speech has been observed to have limited efficacy due to the diverse nature of the associated measured brain waves and the limited number of covert speech databases. As a result, traditional machine learning algorithms for learning and inference are challenging, and one of the real alternatives could be to leverage transfer of learning. The main goals of this research were to create a new deep learning (DL) framework for decoding imagined speech electroencephalography (EEG) signals tasks using transfer learning and to transfer the model learning of the source task of an imagined speech EEG dataset to the model training on the target task of another imagined speech EEG dataset, essentially the cross-task learning transfer of discriminative characteristics of the source task to the target task of imagined speech. The experiment was carried out using two distinct open-access EEG datasets, FEIS and KaraOne, that recorded the imagined speech classes of neural signals from multiple individuals. The target FEIS model and the target KaraOne model for multiclass classification exhibit overall accuracy of 89.01% and 82.35%, respectively, according to the proposed transfer learning. The experiment results indicate that the cross-task deep transfer learning design reliably classifies the imagined speech EEG signals by applying the source task learning to the target task learning. The findings suggest the feasibility of a consistent strategy for classifying multiclass imagined speech with transfer learning, which could thereby open up the possibility of future investigation into cross-task imagined speech classification knowledge usability for generalization of new imagined speech prompts.
{"title":"Decoding of imagined speech electroencephalography neural signals using transfer learning method","authors":"Nrushingh Charan Mahapatra, Prachet Bhuyan","doi":"10.1088/2399-6528/ad0197","DOIUrl":"https://doi.org/10.1088/2399-6528/ad0197","url":null,"abstract":"Abstract The use of brain-computer interfaces to produce imagined speech from brain waves has the potential to assist individuals with difficulty producing speech or communicating silently. The decoding of covert speech has been observed to have limited efficacy due to the diverse nature of the associated measured brain waves and the limited number of covert speech databases. As a result, traditional machine learning algorithms for learning and inference are challenging, and one of the real alternatives could be to leverage transfer of learning. The main goals of this research were to create a new deep learning (DL) framework for decoding imagined speech electroencephalography (EEG) signals tasks using transfer learning and to transfer the model learning of the source task of an imagined speech EEG dataset to the model training on the target task of another imagined speech EEG dataset, essentially the cross-task learning transfer of discriminative characteristics of the source task to the target task of imagined speech. The experiment was carried out using two distinct open-access EEG datasets, FEIS and KaraOne, that recorded the imagined speech classes of neural signals from multiple individuals. The target FEIS model and the target KaraOne model for multiclass classification exhibit overall accuracy of 89.01% and 82.35%, respectively, according to the proposed transfer learning. The experiment results indicate that the cross-task deep transfer learning design reliably classifies the imagined speech EEG signals by applying the source task learning to the target task learning. The findings suggest the feasibility of a consistent strategy for classifying multiclass imagined speech with transfer learning, which could thereby open up the possibility of future investigation into cross-task imagined speech classification knowledge usability for generalization of new imagined speech prompts.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135686091","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 : 2023-09-01DOI: 10.1088/2399-6528/ad0022
H Yorikawa
Abstract The energy states of π -electrons in a graphene nanoflake obtained from graphene, a well-known bipartite lattice or honeycomb lattice of carbon atoms, are studied using the tight-binding method. It is reported that the sublattice imbalance Δ N of the entire graphene nanoflake including vacancy clusters, which characterizes the electronic states, consists of those of the outer and inner edges. In nonzero-energy states, the electrons are evenly distributed between the sublattices A and B, regardless of the value of Δ N . In contrast, zero-energy states are ∣Δ N ∣-fold degenerate states where the electrons are unevenly distributed on either sublattice A or sublattice B. Occasionally, large or specific graphene nanoflakes have substantial zero-energy states, which are mixed states of the nonzero-energy states and zero-energy states.
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Pub Date : 2023-08-11DOI: 10.1088/2399-6528/acefa6
F. De Zela
Classical electrodynamics (CED) has achieved great success in its domain of application, but despite this success, it has remained a theory that lacks complete self-consistency. It is worthwhile trying to make CED a self-consistent theory, because many important phenomena lie within its scope, and because modern field theories have been modelled on it. Alternative approaches to CED might help finding a definite formulation, and they might also lead to the prediction of new phenomena. Here we report two main results. The first one derives from standard CED. It is shown that the motion of a charged particle is ruled not only by the Lorentz equation, but also by equations that are formally identical to Maxwell equations. The latter hold for a velocity field and follow as a strict logical consequence of Hamilton’s action principle for a single particle. We construct a tensor with the velocity field in the same way as the electromagnetic tensor is constructed with the four potential. The two tensors are shown to be proportional to one another. As a consequence, and without leaving the realm of standard CED, one can envision new phenomena for a charged particle, which parallel those involving electromagnetic fields. The second result refers to a field-free approach to CED. This approach confirms the simultaneous validity of Maxwell-like and Lorentz equations as rulers of charged particle motion.
{"title":"Neoclassical models of charged particles","authors":"F. De Zela","doi":"10.1088/2399-6528/acefa6","DOIUrl":"https://doi.org/10.1088/2399-6528/acefa6","url":null,"abstract":"Classical electrodynamics (CED) has achieved great success in its domain of application, but despite this success, it has remained a theory that lacks complete self-consistency. It is worthwhile trying to make CED a self-consistent theory, because many important phenomena lie within its scope, and because modern field theories have been modelled on it. Alternative approaches to CED might help finding a definite formulation, and they might also lead to the prediction of new phenomena. Here we report two main results. The first one derives from standard CED. It is shown that the motion of a charged particle is ruled not only by the Lorentz equation, but also by equations that are formally identical to Maxwell equations. The latter hold for a velocity field and follow as a strict logical consequence of Hamilton’s action principle for a single particle. We construct a tensor with the velocity field in the same way as the electromagnetic tensor is constructed with the four potential. The two tensors are shown to be proportional to one another. As a consequence, and without leaving the realm of standard CED, one can envision new phenomena for a charged particle, which parallel those involving electromagnetic fields. The second result refers to a field-free approach to CED. This approach confirms the simultaneous validity of Maxwell-like and Lorentz equations as rulers of charged particle motion.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42220003","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 : 2023-07-20DOI: 10.1088/2399-6528/ace952
R. Rajaram, N. Ritchey, B. Castellani
The literature on diversity measures, regardless of the metric used (e.g., Gini-Simpson index, Shannon entropy) has a notable gap: not much has been done to connect these measures back to the shape of the original distribution, or to use them to compare the diversity of parts of a given distribution and their relationship to the diversity of the whole distribution. As such, the precise quantification of the relationship between the probability of each type p i and the diversity D in non-uniform distributions, both among parts of a distribution as well as the whole, remains unresolved. This is particularly true for Hill numbers, despite their usefulness as ‘effective numbers’. This gap is problematic as most real-world systems (e.g., income distributions, economic complexity indices, rankings, ecological systems) have unequal distributions, varying frequencies, and comprise multiple diversity types with unknown frequencies that can change. To address this issue, we connect case-based entropy, an approach to diversity we developed, to the shape of a probability distribution; allowing us to show that the original probability distribution g 1, the case-based entropy curve g 2 and the c {1,k} versus the c{1,k}*lnA{1,k} curve g 3, which we call the slope of diversity, are one-to-one (or injective), i.e., a different probability distribution g 1 gives a different curve for g 2 and g 3. Hence, a different permutation of the original probability distribution g 1(that leads to a different shape) will uniquely determine the graphs g 2 and g 3. By proving the injective nature of our approach, we will have established a unique way to measure the degree of uniformity of parts as measured by D P /c P for a given part P of the original probability distribution, and also have shown a unique way to compute the D P /c P for various shapes of the original distribution and (in terms of comparison) for different curves.
{"title":"On the comparison of diversity of parts of a distribution","authors":"R. Rajaram, N. Ritchey, B. Castellani","doi":"10.1088/2399-6528/ace952","DOIUrl":"https://doi.org/10.1088/2399-6528/ace952","url":null,"abstract":"The literature on diversity measures, regardless of the metric used (e.g., Gini-Simpson index, Shannon entropy) has a notable gap: not much has been done to connect these measures back to the shape of the original distribution, or to use them to compare the diversity of parts of a given distribution and their relationship to the diversity of the whole distribution. As such, the precise quantification of the relationship between the probability of each type p i and the diversity D in non-uniform distributions, both among parts of a distribution as well as the whole, remains unresolved. This is particularly true for Hill numbers, despite their usefulness as ‘effective numbers’. This gap is problematic as most real-world systems (e.g., income distributions, economic complexity indices, rankings, ecological systems) have unequal distributions, varying frequencies, and comprise multiple diversity types with unknown frequencies that can change. To address this issue, we connect case-based entropy, an approach to diversity we developed, to the shape of a probability distribution; allowing us to show that the original probability distribution g 1, the case-based entropy curve g 2 and the c {1,k} versus the c{1,k}*lnA{1,k} curve g 3, which we call the slope of diversity, are one-to-one (or injective), i.e., a different probability distribution g 1 gives a different curve for g 2 and g 3. Hence, a different permutation of the original probability distribution g 1(that leads to a different shape) will uniquely determine the graphs g 2 and g 3. By proving the injective nature of our approach, we will have established a unique way to measure the degree of uniformity of parts as measured by D P /c P for a given part P of the original probability distribution, and also have shown a unique way to compute the D P /c P for various shapes of the original distribution and (in terms of comparison) for different curves.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44657990","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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