检索结果-内蒙古大学图书馆

arXiv 2020年

作者： Delgado, Jorge F.M. Herdeiro, Carlos A.R. Radu, Eugen Departamento de Matemática Universidade de Aveiro Center for Research and Development in Mathematics and Applications CIDMA Campus de Santiago Aveiro3810-183 Portugal

We construct and analyse Kerr black holes (BHs) with synchronised axionic hair. These are the BH generalisations of the recently constructed rotating axion boson stars [1]. Such BHs are stationary, axially symmetric, asymptotically flat solutions of the complex Einstein-Klein-Gordon theory with a QCD axion-like potential. They are regular everywhere on and outside the event horizon. The potential is characterised by two parameters: the mass of the axion-like particle, ma and the decay constant fa. The limit fa → ∞ recovers the original example of Kerr BHs with synchronised scalar hair [2]. The effects of the non-linearities in the potential become important for fa . 1. We present an overview of the parameter space of the solutions together with a study of their basic geometric and phenomenological properties, for an illustrative value of the coupling that yields a non-negligible impact of the self-interactions. Copyright © 2020, The Authors. All rights reserved.

关键词： Stars

来源：评论

学校读者我要写书评

暂无评论

Improving production systems with lean: A case study in a medium-sized manufacturer

引用

International Journal of Industrial and Systems Engineering 2019年第2期33卷 162-180页

作者： Vieira, Sérgio Manuel Oliveira Lopes, Rui Borges DEGEIT University of Aveiro Campus Universitário de Santiago Aveiro3810-193 Portugal CIDMA - Center for Research and Development in Mathematics Applications/DEGEIT University of Aveiro Campus Universitário de Santiago Aveiro3810-193 Portugal

Lean principles and tools have been increasingly employed in companies across several sectors, with numerous successful implementations both inside and outside production environments. In the case of Portuguese companies, few works have reported the application and corresponding results of lean, and even fewer focusing on small and medium sized companies. This work presents a case study of an implementation of several lean principles and tools in the production sector of a Portuguese medium-sized screw cap manufacturer. Visual management, A3 thinking, and single-minute exchange of die (SMED) were employed to identify and reduce inefficiencies and waste in the shop floor. The implementation of these principles and tools is detailed, showcasing the necessary adjustments for being correctly embedded in the company's culture. Qualitative and quantitative results are presented concerning the case study, where a continuous improvement culture was adhered to and a significant gain in productivity could be observed. Copyright © 2019 Inderscience Enterprises Ltd.

关键词： Bottles

来源：评论

学校读者我要写书评

暂无评论

Rotating Axion Boson Stars

arXiv

引用

arXiv 2020年

作者： Delgado, Jorge F.M. Herdeiro, Carlos A.R. Radu, Eugen Departamento de Matemática da Universidade de Aveiro Center for Research and Development in Mathematics and Applications CIDMA Campus de Santiago Aveiro3810-183 Portugal

We construct and study rotating axion boson stars (RABSs). These are the spinning generalisations of the spherical gravitating solitons recently introduced in [1]. RABSs are asymptotically flat, stationary, axially symmetric, everywhere regular solutions of the Einstein-Klein-Gordon theory, in the presence of a periodic scalar potential arising in models of axion-like particles. The potential is characterised by two parameters: the mass of the scalar field ma and the decay constant fa. We present an overview of the solution space, for different values of fa, and analyse some of their phenomenological properties. For large decay constants the solutions become identical to the standard spinning mini boson stars. For small decay constants, on the other hand, the solutions develop distinctive features. In particular, we analyse their compactness, the emergence of ergoregions, light rings and the distribution of stable and unstable equatorial timelike circular orbits, including the innermost stable circular orbit. We also establish the occurrence of violations of the strong energy condition for physical observers, for some RABSs. We observe some analogy between RABSs and spinning gravitating Q-balls. Copyright © 2020, The Authors. All rights reserved.

关键词： Bosons

来源：评论

学校读者我要写书评

暂无评论

Optimal control of aquatic diseases: A case study of Yemen’s cholera outbreak

arXiv

引用

arXiv 2020年

作者： Lemos-Paião, Ana P. Silva, Cristiana J. Torres, Delfim F.M. Venturino, Ezio Center for Research and Development in Mathematics and Applications CIDMA Department of Mathematics University of Aveiro Aveiro3810-193 Portugal Department of Mathematics Giuseppe Peano Università di Torino via Carlo Alberto 10 Torino10123 Italy INdAM research group GNCS

We propose a mathematical model for the transmission dynamics of some strains of the bacterium Vibrio cholerae, responsible for the cholera disease in humans. We prove that, when the basic reproduction number is equal to one, a transcritical bifurcation occurs for which the endemic equilibrium emanates from the disease-free point. A control function is introduced into the model, representing the distribution of chlorine water tablets for water purification. An optimal control problem is then proposed and analyzed, where the goal is to determine the fraction of susceptible individuals who should have access to chlorine water tablets in order to minimize the total number of new infections plus the total cost associated with the distribution of chlorine water tablets, over the considered period of time. Finally, we consider real data of the cholera outbreak in Yemen, from 27 April 2017 to 15 April 2018, choosing the values of the parameters of the uncontrolled model that fit the real data. Using our optimal control results, we show, numerically, that the distribution of chlorine water tablets could have stopped, in a fast way, the worst cholera outbreak that ever occurred in human history. Due to the critical situation of Yemen, we also simulate the case where only a small percentage of susceptible individuals has access to chlorine water tablets and obtain an optimal control solution that decreases, substantially, the maximum number of infective individuals attained at the *** Codes 34C60, 49K15, 92D30 Copyright © 2020, The Authors. All rights reserved.

关键词： Diseases

来源：评论

学校读者我要写书评

暂无评论

Uniformly distributed-order wave equation in higher dimensions

引用

AIP Conference Proceedings 2023年第1期2849卷

作者： N. Vieira M. M. Rodrigues M. Ferreira CIDMA-Center for Research and Development in Mathematics and Applications Department of Mathematics-University of Aveiro Campus Universitário de Santiago 3810-193 Aveiro Portugal School of Technology and Management-Polytechnic of Leiria Campus 2 Morro do Lena – Alto do Vieiro P-2411-901 Leiria Portugal

In this short paper, we obtain the eigenfunctions of the uniformly distributed-order wave equation in ℝn× ℝ+, as Laplace integral of Fox H-functions. For the particular case of the first fundamental solution, the fractional moment of second order of the fundamental solution is studied using the Tauberian Theorem.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Eigenfunctions of the time-fractional telegraph equation of distributed order

引用

AIP Conference Proceedings 2023年第1期2849卷

In this work, the eigenfunction problem for the time-fractional telegraph operator of distributed order in ℝn× ℝ+ is con-sidered. By employing the technique of the Fourier, Laplace and Mellin transforms, an integ...

关键词：

来源：评论

学校读者我要写书评

暂无评论

Generalized Fock space and moments

arXiv

引用

arXiv 2020年

作者： Alpay, Daniel A. Cerejeiras, Paula Kähler, Uwe Department of Mathematics Chapman University One University Drive OrangeCA92866 United States CIDMA Center for Research and Development in Mathematics and Applications Department of Mathematics University of Aveiro Campus Universitário de Santiago Aveiro3810-193 Portugal

In this paper we develop a framework to extend the theory of generalized stochastic processes in the Hida white noise space to more general probability spaces which include the grey noise space. To obtain a Wiener-Itô expansion we recast it as a moment problem and calculate the moments explicitly. We further show the importance of a family of topological algebras called strong algebras in this context. Furthermore we show the applicability of our approach to the study of stochastic *** Codes 60H40, 60G22, 33E12, 46F25 Copyright © 2020, The Authors. All rights reserved.

关键词： Algebra

来源：评论

学校读者我要写书评

暂无评论

Data-Driven Carbohydrate Counting Accuracy Monitoring: A Personalized Approach

引用

Procedia Computer Science 2022年 204卷 900-906页

作者： Dbora Amorim Francisco Miranda Lus Ferreira Carlos Abreu ADiT-Lab Instituto Politcnico de Viana do Castelo Rua Escola Industrial e Comercial de Nunlvares 4900-347 Viana do Castelo Portugal Instituto Politcnico de Viana do Castelo Rua Escola Industrial e Comercial de Nunlvares 4900-347 Viana do Castelo Portugal Center for Research and Development in Mathematics and Applications (CIDMA) Department of Mathematics University of Aveiro 3810-193 Aveiro Portugal proMetheus Instituto Politcnico de Viana do Castelo Rua Escola Industrial e Comercial de Nunlvares 4900-347 Viana do Castelo Portugal 2Ai Applied Artificial Intelligence Lab Polytechnic Institute of Cvado and Ave Portugal

Accurate carbohydrate counting is crucial for type 1 diabetes mellitus patients on intensive insulin therapy to get on-target blood glucose values. So, it is fundamental to assess their ability to estimate meals’ carbohydrate content and, if needed, recommend carbohydrate counting training. In this context, we propose a personalized data-driven approach to monitor the patients’ ability to estimate the carbohydrate content of meals. The proposed approach uses personalized data to compute a safe range for the carbohydrate counting error according to the characteristics of each patient and adjust this interval to the patient's daily routines and food habits. Initially, the proposed method uses the insulin-to-carbohydrate ratio, the insulin sensitivity factor, the blood glucose limits, and the blood glucose target to compute a safe interval for the carbohydrate counting error, so the patient could train to reach this goal. Then, the app uses collected daily life data (i.e., blood glucose, meals carbohydrates content, and insulin bolus) to adjust the initial safe interval for the carbohydrate counting error according to the patient's needs. Preliminary assessment using the FDA-approved University of Virginia (UVA)/Padova Type 1 Diabetes Simulator shows the potential of the proposed approach to help type 1 diabetes patients being aware of their needs for carbohydrate counting education and how accurate they should be to achieve suitable blood glucose levels. Therefore, this tool has the potential to be a great asset to healthcare professionals and patients, improving the carbohydrate counting learning outcomes and leading to better glycemic control.

关键词： Healthcare Personalized Medicine Carbohydrate Counting Education Accurate Carbohydrate Counting

来源：评论

学校读者我要写书评

暂无评论

A framework to support quality data mart solutions: An approach developed based on practical cases 4

A framework to support quality data mart solutions: An appro...

引用

4th International Conference on Quality Engineering and Management, ICQEM 2020

作者： Mendes, A.R. Teixeira, L. Alvelos, H. Department of Economics Management Industrial Engineering and Tourism University of Aveiro Aveiro3810-193 Portugal Department of Economics Management Industrial Engineering and Tourism Institute of Electronics and Informatics Engineering of Aveiro University of Aveiro Aveiro3810-193 Portugal Department of Economics Management Industrial Engineering and Tourism Center for Research and Development in Mathematics and Applications University of Aveiro Aveiro3810-193 Portugal

ISBN: (纸本)9789895491100

Purpose - Today, due to the large amount of data available in companies, solutions for extracting information and knowledge to support decision-making processes are needed. To address this issue, data mart implementation with proper dashboard can represent good solutions. However, due to the complexity involved in this kind of projects and its multidisciplinary nature, appropriate methodologies for conducting data mart development are needed. The present study aims to propose a framework to guide the process of development of quality data marts in a Portuguese electronics company. Methodology - The methodology used to conduct this study combined the principles of two well-known approaches - DMAIC and BPM. The first was useful in addressing and understanding the problem, while the second was used to guide the process. Two practical cases were used, the first as an experimental scenario and the second one as a testing scenario. Findings - The main result of this study is a ready to use framework to guide industrialization teams in development of quality data marts to help users in their decision-making processes. Originality/value - As there are no standard procedures available for companies to implement quality data mart solutions, the proposed framework, which is easy to apply, can be a valuable tool when a company wants to industrialize a new product. It can also be valuable for researchers working at the interface of the Quality and Information Systems areas. © 2020 Universidade do Minho. All rights reserved.

关键词： BPM lifecycle BPMN 2.0 Data Mart DMAIC Quality

来源：评论

学校读者我要写书评

暂无评论

Compactness bounds in general relativity

引用

Physical Review D 2022年第4期106卷 L041502-L041502页

作者： Artur Alho José Natário Paolo Pani Guilherme Raposo Center for Mathematical Analysis Geometry and Dynamical Systems Instituto Superior Técnico Universidade de Lisboa Av. Rovisco Pais 1049-001 Lisboa Portugal Dipartimento di Fisica Sapienza Università di Roma & INFN Roma1 Piazzale Aldo Moro 5 00185 Roma Italy CENTRA Instituto Superior Técnico Universidade de Lisboa Av. Rovisco Pais 1049-001 Lisboa Portugal Centre for Research and Development in Mathematics and Applications (CIDMA) Campus de Santiago 3810-183 Aveiro Portugal

A foundational theorem due to Buchdahl states that, within general relativity (GR), the maximum compactness C≡GM/(Rc2) of a static, spherically symmetric, perfect fluid object of mass M and radius R is C=4/9. As a corollary, there exists a compactness gap between perfect fluid stars and black holes (where C=1/2). Here we generalize Buchdahl’s result by introducing the most general equation of state for elastic matter with constant longitudinal wave speeds and apply it to compute the maximum compactness of regular, self-gravitating objects in GR. We show that: (i) the maximum compactness grows monotonically with the longitudinal wave speed; (ii) elastic matter can exceed Buchdahl’s bound and reach the black hole compactness C=1/2 continuously; (iii) however, imposing subluminal wave propagation lowers the maximum compactness bound to C≈0.462, which we conjecture to be the maximum compactness of any static elastic object satisfying causality; (iv) imposing also radial stability further decreases the maximum compactness to C≈0.389. Therefore, although anisotropies are often invoked as a mechanism for supporting horizonless ultracompact objects, we argue that the black hole compactness cannot be reached with physically reasonable matter within GR and that true black hole mimickers require either exotic matter or beyond-GR effects.

关键词： General relativity Gravitation

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：