Hasil untuk "Periodicals"

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S2 Open Access 2010
Hesitant fuzzy sets

V. Torra

Several extensions and generalizations of fuzzy sets have been introduced in the literature, for example, Atanassov's intuitionistic fuzzy sets, type 2 fuzzy sets, and fuzzy multisets. In this paper, we propose hesitant fuzzy sets. Although from a formal point of view, they can be seen as fuzzy multisets, we will show that their interpretation differs from the two existing approaches for fuzzy multisets. Because of this, together with their definition, we also introduce some basic operations. In addition, we also study their relationship with intuitionistic fuzzy sets. We prove that the envelope of the hesitant fuzzy sets is an intuitionistic fuzzy set. We prove also that the operations we propose are consistent with the ones of intuitionistic fuzzy sets when applied to the envelope of the hesitant fuzzy sets. © 2010 Wiley Periodicals, Inc.

1778 sitasi en Computer Science
S2 Open Access 2003
An iterative thresholding algorithm for linear inverse problems with a sparsity constraint

I. Daubechies, M. Defrise, C. D. Mol

We consider linear inverse problems where the solution is assumed to have a sparse expansion on an arbitrary preassigned orthonormal basis. We prove that replacing the usual quadratic regularizing penalties by weighted 𝓁p‐penalties on the coefficients of such expansions, with 1 ≤ p ≤ 2, still regularizes the problem. Use of such 𝓁p‐penalized problems with p < 2 is often advocated when one expects the underlying ideal noiseless solution to have a sparse expansion with respect to the basis under consideration. To compute the corresponding regularized solutions, we analyze an iterative algorithm that amounts to a Landweber iteration with thresholding (or nonlinear shrinkage) applied at each iteration step. We prove that this algorithm converges in norm. © 2004 Wiley Periodicals, Inc.

5312 sitasi en Mathematics, Computer Science
arXiv Open Access 2026
Additive-Functional Approach to Transport in Periodic and Tilted Periodic Potentials

Sang Yang, Zhixin Peng

In this Letter, we clarify the physical origin of effective transport in periodic and tilted periodic systems. When Brownian dynamics is examined on the scale of a single period, the particle displacement admits a natural separation into a bounded part associated with recurrent motion within the periodic landscape, and an unbounded stochastic part that grows in time and carries the net transport. We show that effective drift and diffusion are governed entirely by this unbounded component, while local potential-induced fluctuations contribute only bounded corrections. Treating the displacement as an additive functional of the stochastic dynamics provides a rigorous formulation of this separation and leads to a corrector-martingale representation at the trajectory level. Within this framework, classical results-including the Lifson-Jackson formula for unbiased periodic systems and the Stratonovich expressions for tilted periodic potentials-follow as direct consequences of the same underlying structure. The same perspective extends naturally to higher-dimensional periodic environments, recovering the standard homogenized transport tensors.

en cond-mat.stat-mech, math.PR
arXiv Open Access 2025
Period-LLM: Extending the Periodic Capability of Multimodal Large Language Model

Yuting Zhang, Hao Lu, Qingyong Hu et al.

Periodic or quasi-periodic phenomena reveal intrinsic characteristics in various natural processes, such as weather patterns, movement behaviors, traffic flows, and biological signals. Given that these phenomena span multiple modalities, the capabilities of Multimodal Large Language Models (MLLMs) offer promising potential to effectively capture and understand their complex nature. However, current MLLMs struggle with periodic tasks due to limitations in: 1) lack of temporal modelling and 2) conflict between short and long periods. This paper introduces Period-LLM, a multimodal large language model designed to enhance the performance of periodic tasks across various modalities, and constructs a benchmark of various difficulty for evaluating the cross-modal periodic capabilities of large models. Specially, We adopt an "Easy to Hard Generalization" paradigm, starting with relatively simple text-based tasks and progressing to more complex visual and multimodal tasks, ensuring that the model gradually builds robust periodic reasoning capabilities. Additionally, we propose a "Resisting Logical Oblivion" optimization strategy to maintain periodic reasoning abilities during semantic alignment. Extensive experiments demonstrate the superiority of the proposed Period-LLM over existing MLLMs in periodic tasks. The code is available at https://github.com/keke-nice/Period-LLM.

en cs.CV
DOAJ Open Access 2024
In-Depth Examination of Coverage Duration: Analyzing Years Covered and Skipped in Journal Indexing

Eungi Kim

Journals that have consistently maintained uninterrupted indexing over an extended period can be assumed to possess stability and sustainability in journal indexing. Building on this assumption, the objective of this study is to scrutinize the years omitted in the indexing of Scopus-indexed journals. To conduct this study, three coverage duration indicators—nyears-covered (total years covered), nyears-skipped (years skipped), and skipped/covered ratio (proportion of years skipped to total years covered)—were formulated. Data from SCImago Journal Rank (SJR) for 2022, consisting of 16,762 records (62% of downloaded data) with a coverage duration of 25 years or less, were used for this study. The results revealed that around 10% of Scopus-indexed journals experienced exclusions or coverage gaps. Longer coverage correlates positively with documents published, h-index, and citations, while skipped years decrease with these indicators. Open access (OA) journals exhibited a lower skipped/covered ratio than non-OA journals, suggesting a better sustainability of indexing than non-OA journals. Disciplinary differences in Scopus journal coverage duration revealed notable variation, suggesting that coverage duration indicators can be effectively used to evaluate journal stability within Scopus. Overall, the coverage gaps reflect Scopus’s efforts to regulate the journals it indexes. The coverage duration indicators proposed in this study can be applied to assess the stability of periodicals in any database, providing insights into the broader dynamics and quality standards maintained by a database, where the database periodically adds and removes its indexed contents.

Communication. Mass media, Information resources (General)

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