Journal of Physics Communications最新文献_第4页

The blue color mechanism on sapphires from different gem deposits before and after heating under oxidizing atmosphere 不同宝石矿床的蓝宝石在氧化气氛下加热前后的蓝色机理

IF 1.2

Journal of Physics Communications Pub Date : 2023-12-20 DOI: 10.1088/2399-6528/ad1762

Wanvisa Thengthong, S. Sakkaravej, Wiwat Wongkokua, C. Saiyasombat, N. Monarumit

{"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}

引用次数: 0

Classical relativistic electron-field dynamics: Hamiltonian approach to radiation reaction 经典相对论电子场动力学：辐射反应的哈密顿方法

IF 1.2

Journal of Physics Communications Pub Date : 2023-12-13 DOI: 10.1088/2399-6528/ad1049

R F Álvarez-Estrada, I Pastor, L Roso, F Castejón

{"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>\u0000max 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\u0000<italic toggle=\"yes\">RR</italic>\u0000 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\u0000<italic toggle=\"yes\">RR</italic>\u0000 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}

引用次数: 0

A tale of analogies: a review on gravitomagnetic effects, rotating sources, observers and all that 一个类比的故事:对重力磁效应、旋转源、观察者和所有这些的回顾

Journal of Physics Communications Pub Date : 2023-11-02 DOI: 10.1088/2399-6528/ad08cf

Matteo Luca Ruggiero, Davide Astesiano

引用次数: 2

A new method that automatically regularizes scattering amplitudes 一种自动正则化散射振幅的新方法

Journal of Physics Communications Pub Date : 2023-10-24 DOI: 10.1088/2399-6528/ad0649

Nagabhushana Prabhu

引用次数: 0

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 用分子相互作用体积模型计算Sn- au - cu三元液态合金混合过程中Sn活度和整体多余自由能变化

Journal of Physics Communications Pub Date : 2023-10-13 DOI: 10.1088/2399-6528/ad035a

Sanjay Kumar Sah, Ishwar Koirala

引用次数: 0

From newton to universal planck natural units – disentangling the constants of nature 从牛顿到普朗克自然单位——解开自然常数的纠缠

Journal of Physics Communications Pub Date : 2023-10-05 DOI: 10.1088/2399-6528/ad0090

Andrew Wutke

{"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}

引用次数: 0

Decoding of imagined speech electroencephalography neural signals using transfer learning method 用迁移学习方法解码想象语音脑电图神经信号

Journal of Physics Communications Pub Date : 2023-09-01 DOI: 10.1088/2399-6528/ad0197

Nrushingh Charan Mahapatra, Prachet Bhuyan

{"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}

引用次数: 0

Sublattice imbalance of states in graphene nanoflakes 石墨烯纳米片中亚晶格状态的不平衡

Journal of Physics Communications Pub Date : 2023-09-01 DOI: 10.1088/2399-6528/ad0022

H Yorikawa

引用次数: 0

Neoclassical models of charged particles 带电粒子的新古典模型

IF 1.2

Journal of Physics Communications Pub Date : 2023-08-11 DOI: 10.1088/2399-6528/acefa6

F. De Zela

{"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}

引用次数: 0

On the comparison of diversity of parts of a distribution 关于分布各部分多样性的比较

IF 1.2

Journal of Physics Communications Pub Date : 2023-07-20 DOI: 10.1088/2399-6528/ace952

R. Rajaram, N. Ritchey, B. Castellani

{"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}

引用次数: 0