摘要:
Herschend–Liu–Nakaoka introduced the notion of an n-exangulated category. It is not only a higher dimensional analogue of extriangulated categories defined by Nakaoka–Palu, but also gives a simultaneous generalization of n-exact categories and
$$(n+2)$$
-angulated categories. In this article, we give an n-exangulated version of Auslander’s defect and Auslander–Reiten duality formula. Moreover, we also give a classification of substructures (=closed subbifunctors) of a given skeletally small n-exangulated category by using the category of defects.
摘要:
In this paper, the localized method of fundamental solutions (LMFS) with coupling the dual reciprocity method (DRM) is applied to simulate three-space dimensional nonlinear wave equations. First, DRM, which is a popular meshless method based on polyharmonic splines (PhS), is applied to obtain the particular solution. After evaluating the particular solution, 3D-LMFS method can be employed to evaluate the homogeneous solution. The proposed 3D-LMFS algorithms construct 3D artificial surfaces where source points and then the collocation procedure propose by using the fundamental solutions in each 3D surface. Straightforwardly, a solution to the 3D wave equation is approximated by a sum of the combination of PhS and fundamental solutions using LMFS. Eventually, the scheme has been prosperously tested with selected examples.
期刊:
Communications in Statistics - Theory and Methods,2023年 ISSN:0361-0926
通讯作者:
Li, YQ
作者机构:
[Li, Yingqiu; Wang, Hesong; Tang, Xinping] Changsha Univ Sci & Technol, Sch Math & Stat, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha, Hunan, Peoples R China.;[Li, Yingqiu; Li, YQ] Changsha Univ Sci & Technol, Sch Math & Stat, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410004, Hunan, Peoples R China.
通讯机构:
[Li, YQ ] C;Changsha Univ Sci & Technol, Sch Math & Stat, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410004, Hunan, Peoples R China.
关键词:
Branching processes with immigration;random environment;central limit theorem;exact convergence rate
摘要:
Let {Zn} be a supercritical branching process with immigration in an independent, identically distributed(i.i.d.) environment xi. The Berry-Esseen bound for logZn has been established by Wang et al. (2021). To refine that, under the less restrictive moment conditions, we calculate the exact convergence rate in the central limit theorem for logZn under the annealed law.
摘要:
Synchronization of memristive neural networks (MNNs) by using network control scheme has been widely and deeply studied. However, these researches are usually restricted to traditional continuous-time control methods for synchronization of the first-order MNNs. In this paper, we study the robust exponential synchronization of inertial memristive neural networks (IMNNs) with time-varying delays and parameter disturbance via event-triggered control (ETC) scheme. First, the delayed IMNNs with parameter disturbance are changed into first-order MNNs with parameter disturbance by constructing proper variable substitutions. Next, a kind of state feedback controller is designed to the response IMNN with parameter disturbance. Based on feedback controller, some ETC methods are provided to largely decrease the update times of controller. Then, some sufficient conditions are provided to realize robust exponential synchronization of delayed IMNNs with parameter disturbance via ETC scheme. Moreover, the Zeno behavior will not happen in all ETC conditions shown in this paper. Finally, numerical simulations are given to verify the advantages of the obtained results such as anti-interference performance and good reliability.
期刊:
European Physical Journal Plus,2023年138(3):1-8 ISSN:2190-5444
通讯作者:
Fei, S.-M.;Zhang, Q.-H.
作者机构:
[Zhang, Qing-Hua; Fei, Shao-Ming; Wu, Jing-Feng] Capital Normal Univ, Sch Math Sci, Beijing 100048, Peoples R China.;[Fei, Shao-Ming] Max Planck Inst Math Sci, D-04103 Leipzig, Germany.;[Zhang, Qing-Hua] Changsha Univ Sci & Technol, Sch Math & Stat, Changsha 410114, Peoples R China.
通讯机构:
[Qing-Hua Zhang; Shao-Ming Fei] S;School of Mathematical Sciences, Capital Normal University, Beijing, China<&wdkj&>School of Mathematics and Statistics, Changsha University of Science and Technology, Changsha, China<&wdkj&>School of Mathematical Sciences, Capital Normal University, Beijing, China<&wdkj&>Max-Planck-Institute for Mathematics in the Sciences, Leipzig, Germany
摘要:
The uncertainty principle is one of the fundamental features of quantum mechanics and plays an essential role in quantum information theory. We study uncertainty relations based on variance for arbitrary finite N quantum observables. We establish a series of parameterized uncertainty relations in terms of the parameterized norm inequalities, which improve the exiting variance-based uncertainty relations. The lower bounds of our uncertainty inequalities are non-zero unless the measured state is a common eigenvector of all the observables. Detailed examples are provided to illustrate the tightness of our uncertainty relations.
期刊:
International Journal of Finance & Economics,2023年28(2):1201-1213 ISSN:1076-9307
通讯作者:
Huang, Chuangxia
作者机构:
[Yang, Xin; Chen, Shan; Huang, Chuangxia] Changsha Univ Sci & Technol, Sch Math & Stat, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Hunan, Peoples R China.;[Liu, Hong] Cent South Univ Forestry & Technol, Sch Econ, Changsha, Hunan, Peoples R China.;[Yang, Xiaoguang] Chinese Acad Sci, Acad Math & Syst Sci, Beijing, Peoples R China.
通讯机构:
[Huang, Chuangxia] C;Changsha Univ Sci & Technol, Sch Math & Stat, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Hunan, Peoples R China.
关键词:
Financial institution network;jump volatility;panel data regression model
摘要:
The identification of systemically important financial institutions (SIFIs) is an important measure to deal with systemic risks. To achieve this goal, we first use generalized variance decomposition method and granger causality test to construct jump volatility spillover networks of Chinese financial institutions based on the 5-min high-frequency data. Then, out-strength and in-strength are adopted to analyze the SIFI. Finally, we use panel data regression model to investigate the determinant of the SIFIs. The empirical results show that: (a) The network density reaches a peak when the financial system under pressure during the China's stock market disaster of 2015. (b) Large banks and insurances usually display systemic importance, while some small financial institutions are also SIFIs due to their high value of out-strength and in-strength. (c) There are obvious differences in the factors that affect the out-strength and in-strength based on panel data regression model, but turnover rate, jump volatility, firm size and growth rate of total assets are the common driving factors.
摘要:
Abstract: In order to verify the effectiveness of multi-scale algorithm on the elastic stiffness parameters of asphalt mixture, this paper analyzes the characteristics of multi-scale algorithm and the fine model of asphalt mixture, and proposes the theoretical method and characterization of multi-scale algo-rithm for random composite materials. The distribution characteristics of fine aggregate of asphalt mixture with different particle sizes are counted, the fine aggregate is randomly generated in the scale area according to the distribution characteristics of aggregate, and the scale area of various kinds of asphalt mixture is selected to calculate the scale, and the fine scale model is generated in the scale area according to the random distribution characteristics of aggregate. A multi-scale algo-rithm is used to predict the stiffness parameters of the fatigue process of asphalt mixture. The con-clusion is that the multi-scale algorithm is effective for the stiffness parameter of asphalt mixture, and this algorithm can provide some reference significance for similar practical engineering.#@#@#摘要: 为了验证多尺度算法对沥青混合料的弹性力学刚度参数的有效性问题,本文分析了多尺度算法及沥青混合料细观模型特性,提出了多尺度算法运用于随机复合材料的理论方法及表征。统计含不同粒径集料沥青混合料细观骨料分布特性,依据骨料分布特性规律在尺度区域内随机生成细观骨料,选取各类沥青混合料计算尺度区域,依据骨料随机分布特性在尺度区域内生成细观尺度模型。运用多尺度算法预测沥青混合料疲劳过程刚度参数,提出了计算沥青混合料疲劳损伤过程刚度参数的多尺度算法流程。结论是多尺度算法用于沥青混合料的刚度参数是有效的,该算法可以为类似的实际工程提供一定的参考意义。
摘要:
It was shown recently that the heart of a twin cotorsion pair on an extriangulated category is semi-abelian. In this article, we consider a special class of hearts of twin cotorsion pairs induced by d-cluster tilting subcategories in extriangulated categories. We give a necessary and sufficient condition for such hearts to be abelian. In particular, we can also see that such hearts are hereditary. As an application, this generalizes the work by Liu in the exact case, thereby providing new insights into the triangulated case.
期刊:
IEEE Transactions on Medical Imaging,2023年:1-1 ISSN:0278-0062
作者机构:
[Xiaofei Huang; Hongfang Gong] School of Mathematics and Statistics, Changsha University of Science and Technology, Changsha, China
关键词:
Medical visual question answering;double embedding;medical information;guided attention;visual reasoning
摘要:
Research in medical visual question answering (MVQA) can contribute to the development of computer-aided diagnosis. MVQA is a task that aims to predict accurate and convincing answers based on given medical images and associated natural language questions. This task requires extracting medical knowledge-rich feature content and making fine-grained understandings of them. Therefore, constructing an effective feature extraction and understanding scheme are keys to modeling. Existing MVQA question extraction schemes mainly focus on word information, ignoring medical information in the text, such as medical concepts and domain-specific terms. Meanwhile, some visual and textual feature understanding schemes cannot effectively capture the correlation between regions and keywords for reasonable visual reasoning. In this study, a dual-attention learning network with word and sentence embedding (DALNet-WSE) is proposed. We design a module, transformer with sentence embedding (TSE), to extract a double embedding representation of questions containing keywords and medical information. A dual-attention learning (DAL) module consisting of self-attention and guided attention is proposed to model intensive intramodal and intermodal interactions. With multiple DAL modules (DALs), learning visual and textual co-attention can increase the granularity of understanding and improve visual reasoning. Experimental results on the ImageCLEF 2019 VQA-MED (VQA-MED 2019) and VQA-RAD datasets demonstrate that our proposed method outperforms previous state-of-the-art methods. According to the ablation studies and Grad-CAM maps, DALNet-WSE can extract rich textual information and has strong visual reasoning ability.
摘要:
This paper studies the relationship between three types of risk borne by banks and climate policy uncertainty (CPU). We use panel data for 210 commercial banks in China from 2009 to 2020. This paper has the following main conclusions: Firstly, climate policy uncertainty significantly reduce the passive and active risks borne by banks and increase the insolvency risks borne by banks; Secondly, the impact of CPU on the passive risks borne by listed banks is greater than that of unlisted banks, and the impact of CPU on the active and insolvency risks borne by listed banks is less than that of unlisted banks; Thirdly, the impact of CPU on the three types of risks borne by banks is most pronounced among rural banks and state-owned banks and least pronounced among joint-stock banks. After a series of robustness tests, such as the system GMM approach, different sample periods and controlling for endogeneity, the results of this paper remain robust. We also used the difference in difference (DID) method to study the policy dynamic effects of the 2016 Paris Agreement, and we passed a parallel trend test. Our results provide insights for policy makers and investors. Policy makers should formulate visionary policies in order to minimize the adverse effects of CPU; investors should keep an eye on the implementation of climate policies and pay attention to the impact of policies on the economy, so that they can adjust their in-vestment strategies rationally.
关键词:
Multistability;Switched complex-valued neural network;State-dependent;Equilibrium point
摘要:
The paper focuses on the multistability problems of the switched complex-valued neural networks with state-dependent switching rules. Based on the differential inclusions theory and fixed point theorem, sev-eral sufficient conditions are derived to ascertain that there exist 25n equilibria, 9n of which are locally ex for n-neuron switched complex-valued neural networks. The number of stable equilibria of an n-neuron switched complex-valued neural network increases significantly from 4n to 9n compared with the con-ventional complex-valued neural networks. Finally, four numerical examples are presented to substanti-ate the theoretical results. & COPY; 2023 Elsevier B.V. All rights reserved.
摘要:
We present a meshless method to assess the inverse heat problem (IHP) on multi-dimensional (multi -D) by the correcting functions. Fulfillment of the scheme is a reformulation of the IHP equation as an operator equation subjected to the boundary condition. The solution of ill-conditioned IHP is expressed in the term of the trigonometric basis function (TBF) on the available boundary data which is corrupted with a small parameter in the noisy data. When the data contain noise or extra measured data, we try out the practical performance of the scheme with different values of parameters and illustrate acceptable estimates for the local error.(c) 2023 Elsevier Ltd. All rights reserved.
期刊:
Energy Economics,2023年124:106880 ISSN:0140-9883
通讯作者:
Dai, Zhifeng(zhifengdai823@163.com)
作者机构:
[Dai, Zhifeng; Tang, Rui] College of Mathematics and Statistics, Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science and Technology, Hunan, 410114, China;[Zhang, Xiaotong] School of Economics and Management, Changsha University of Science and Technology, Hunan, 410114, China
通讯机构:
[Zhifeng Dai] C;College of Mathematics and Statistics, Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science and Technology, Hunan 410114, China
摘要:
As an active heat transfer enhancement technique, electrohydrodynamic has excellent potential to enhance the melting rate during solid-liquid phase change. In this work, the lattice Boltzmann method is adopted to investigate the electrohydrodynamic enhancement of solid-liquid phase change in three-dimensional cavities. The numerical method is firstly validated by several carefully chosen test cases, and then we conducted simulations under different governing parameters and aspect ratios. Results show that the interface morphologies obtained from pure electro-convection and pure thermo-convection are significantly different due to the different directions of the buoyancy and Coulomb forces. Besides, the augmentation of melting due to the electric effect becomes significant when the electric driving parameter T increases. For sufficiently high values of T, the melting performance is mainly dominated by the Coulomb force, and the influence of the thermal Rayleigh number in such a case is insignificant. Further, we note that the melting performance in the enclosure depends on the aspect ratio, and the lateral wall in a three-dimensional cavity with a relatively smaller aspect ratio usually inhibits the electro-convection. Finally, a comparison between the two-dimensional and three-dimensional simulations shows that the added dimension significantly affects the flow dynamics and the interface shape, which cannot be ignored for similar problems.