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A Unified Version of Weighted Weak-Type Inequalities for the One-Sided Hardy–Littlewood Maximal Function in Orlicz Classes 奥立兹类中单边哈代-利特尔伍德最大函数的加权弱式不等式的统一版本
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-11 DOI: 10.3390/math12182814
Erxin Zhang
Let Mg+f be the one-sided Hardy–Littlewood maximal function, φ1 be a nonnegative and nondecreasing function on [0,∞), γ be a positive and nondecreasing function defined on [0,∞); let φ2 be a quasi-convex function and u,v,w be three weight functions. In this paper, we present necessary and sufficient conditions on weight functions (u,v,w) such that the inequality φ1(λ)∫{Mg+f>λ}u(x)g(x)dx≤C∫−∞+∞φ2(C|f(x)|v(x)γ(λ))w(x)g(x)dx holds. Then, we unify the weak and extra-weak-type one-sided Hardy–Littlewood maximal inequalities in the above inequality.
设 Mg+f 为单边哈代-利特尔伍德最大函数,φ1 为定义在 [0,∞) 上的非负且非递减函数,γ 为定义在 [0,∞) 上的正且非递减函数;设φ2 为准凸函数,u,v,w 为三个权函数。本文提出了权重函数(u,v,w)的必要条件和充分条件,使得不等式φ1(λ)∫{Mg+f>λ}u(x)g(x)dx≤C∫-∞+∞φ2(C|f(x)|v(x)γ(λ))w(x)g(x)dx 成立。然后,我们把弱型和超弱型单边哈代-利特尔伍德最大不等式统一到上述不等式中。
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引用次数: 0
Sojourn Time Analysis of a Single-Server Queue with Single- and Batch-Service Customers 具有单个和批量服务客户的单服务器队列的停留时间分析
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-11 DOI: 10.3390/math12182820
Yusei Koyama, Ayane Nakamura, Tuan Phung-Duc
There are various types of sharing economy services, such as ride-sharing and shared-taxi rides. Motivated by these services, we consider a single-server queue in which customers probabilistically select the type of service, that is, the single service or batch service, or other services (e.g., train). In the proposed model, which is denoted by the M+M(K)/M/1 queue, we assume that the arrival process of all the customers follows a Poisson distribution, the batch size is constant, and the common service time (for the single- and batch-service customers) follows an exponential distribution. In this model, the derivation of the sojourn time distribution is challenging because the sojourn time of a batch-service customer is not determined upon arrival but depends on single customers who arrive later. This results in a two-dimensional recursion, which is not generally solvable, but we made it possible by utilizing a special structure of our model. We present an analysis using a quasi-birth-and-death process, deriving the exact and approximated sojourn time distributions (for the single-service customers, batch-service customers, and all the customers). Through numerical experiments, we demonstrate that the approximated sojourn time distribution is sufficiently accurate compared to the exact sojourn time distributions. We also present a reasonable approximation for the distribution of the total number of customers in the system, which would be challenging with a direct-conventional method. Furthermore, we presented an accurate approximation method for a more general model where the service time of single-service customers and that of batch-service customers follow two distinct distributions, based on our original model.
共享经济服务有多种类型,如共享乘车和共享出租车。受这些服务的启发,我们考虑了一个单服务器队列,在该队列中,客户概率性地选择服务类型,即单次服务或批量服务,或其他服务(如火车)。在所提出的模型(用 M+M(K)/M/1 队列表示)中,我们假设所有顾客的到达过程都服从泊松分布,批量大小恒定,并且共同服务时间(对于单次服务和批量服务顾客)服从指数分布。在这个模型中,逗留时间分布的推导具有挑战性,因为批量服务客户的逗留时间不是在到达时确定的,而是取决于随后到达的单个客户。这就产生了一个二维递归,一般来说是无法求解的,但我们利用模型的特殊结构将其变为可能。我们利用准生死过程进行分析,推导出(单个服务客户、批量服务客户和所有客户的)精确和近似逗留时间分布。通过数值实验,我们证明近似的停留时间分布与精确的停留时间分布相比足够精确。我们还提出了系统中客户总数分布的合理近似值,而这对于直接采用传统方法是一个挑战。此外,我们还在原有模型的基础上,针对单次服务客户的服务时间和批量服务客户的服务时间遵循两种不同分布的更一般模型,提出了一种精确的近似方法。
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引用次数: 0
Correction: Muniyappan et al. Stability and Numerical Solutions of Second Wave Mathematical Modeling on COVID-19 and Omicron Outbreak Strategy of Pandemic: Analytical and Error Analysis of Approximate Series Solutions by Using HPM. Mathematics 2022, 10, 343 更正:Muniyappan 等人.关于 COVID-19 和大流行病 Omicron 爆发策略的第二波数学模型的稳定性和数值解:使用 HPM 的近似数列解的分析和误差分析.数学 2022,10,343
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-11 DOI: 10.3390/math12182816
Ashwin Muniyappan, Balamuralitharan Sundarappan, Poongodi Manoharan, Mounir Hamdi, Kaamran Raahemifar, Sami Bourouis, Vijayakumar Varadarajan
In the original publication [...]
在最初的出版物中 [...]
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引用次数: 0
Performance Evaluation of the Taiwanese Banking Industry before and after the COVID-19 Pandemic 台湾银行业在 COVID-19 大流行前后的绩效评估
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-11 DOI: 10.3390/math12182817
Chuan-Feng Lee, Fu-Chiang Yang
This study aimed to explore efficiency changes in Taiwan’s banking industry before and after the outbreak of coronavirus disease 2019 (COVID-19) by using the maximum slacks-based measure approach. The data, spanning from 2018 to 2021, categorized banks into three systems: state-owned, private, and foreign. Bank performance was measured from two perspectives: single-period evaluation (assessing bank performance in each year individually) and cross-period evaluation (assessing bank performance from 2018 to 2021 collectively). Inter-temporal changes in bank performance across the three banking systems were analyzed. The results indicated that only foreign banks rebounded rapidly after the COVID-19 outbreak, while the average performance of private banks remained stagnant, and state-owned banks performed worse than before the outbreak. Therefore, it is recommended that state-owned banks develop effective and rapid improvement policies to address major emergencies. Additionally, the study found that inefficiencies in banks were due to excessive input resources and/or failure to achieve the output targets. The input–output gap of inefficient banks was also analyzed, providing learning benchmarks and clear improvement targets that can help these banks formulate practical actions to improve their performance.
本研究旨在利用基于最大松弛的计量方法,探讨台湾银行业在2019年冠状病毒病(COVID-19)爆发前后的效率变化。数据时间跨度为 2018 年至 2021 年,将银行分为国有、民营和外资三种体系。银行绩效从两个角度进行衡量:单期评估(单独评估银行在每一年的绩效)和跨期评估(共同评估银行在 2018 年至 2021 年的绩效)。分析了三种银行体系中银行绩效的跨期变化。结果表明,只有外资银行在 COVID-19 爆发后迅速反弹,而民营银行的平均绩效仍然停滞不前,国有银行的绩效比疫情爆发前更差。因此,建议国有银行制定有效、快速的改进政策,以应对重大突发事件。此外,研究还发现,银行效率低下的原因是投入资源过多和/或未能实现产出目标。研究还分析了低效率银行的投入产出差距,提供了学习基准和明确的改进目标,有助于这些银行制定切实可行的行动来提高绩效。
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引用次数: 0
An Outlier Detection Approach to Recognize the Sources of a Process Failure within a Multivariate Poisson Process 在多变量泊松过程中识别过程故障源的离群值检测方法
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-11 DOI: 10.3390/math12182813
Chia-Ding Hou, Rung-Hung Su
Among attribute processes, the number of nonconformities conforming to a Poisson distribution is among the most crucial quality attributes. Furthermore, owing to the variety of quality attributes, the significance of the multivariate Poisson process in industry cannot be overstated. An out-of-control multivariate Poisson process can be detected using an alarm on a multivariate control chart. Nevertheless, pinpointing the specific quality attributes that led to the process shifts is complex. The study focuses on the causes that lead to process shifts in multivariate Poisson processes, unlike the majority of studies examining shifts in multivariate normal processes. This paper initially presents a statistical method for detecting outliers in a multivariate Poisson distribution. Furthermore, a progressive testing algorithm is then developed to identify the variables responsible for a failure within a multivariate Poisson process. According to simulation results, the proposed approach can effectively determine the sources of a process fault within a multivariate Poisson process.
在属性过程中,符合泊松分布的不合格数量是最关键的质量属性之一。此外,由于质量属性的多样性,多元泊松过程在工业中的重要性怎么强调都不为过。失控的多元泊松过程可以通过多元控制图上的警报来检测。然而,确定导致过程转变的具体质量属性非常复杂。与大多数研究多变量正态过程偏移的研究不同,本研究重点关注导致多变量泊松过程偏移的原因。本文首先介绍了一种在多元泊松分布中检测异常值的统计方法。此外,本文还开发了一种渐进测试算法,以确定在多元泊松过程中造成故障的变量。根据模拟结果,所提出的方法能有效确定多元泊松过程中的过程故障源。
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引用次数: 0
Unified Gas Kinetic Simulations of Lid-Driven Cavity Flows: Effect of Compressibility and Rarefaction on Vortex Structures 盖驱动空腔流的统一气体动力学模拟:可压缩性和稀膨胀对涡旋结构的影响
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-11 DOI: 10.3390/math12182807
Vishnu Venugopal, Haneesha Iphineni, Divya Sri Praturi, Sharath S. Girimaji
We investigate and characterize the effect of compressibility and rarefaction on vortex structures in the benchmark lid-driven cavity flow. Direct numerical simulations are performed, employing the unified gas kinetic scheme to examine the changes in vortex generation mechanisms and the resulting flow structures at different Mach and Knudsen numbers. At high degrees of rarefaction, where inter-molecular interactions are minimal, the molecules mainly collide with the walls. Consequently, the dominant flow structure is a single vortex in the shape of the cavity. It is shown that increasing compressibility or decreasing rarefaction lead to higher molecular density in the cavity corners, due to more frequent inter-molecular collisions. This results in lower flow velocities, creating conditions conducive to the development of secondary and corner vortices. The physical processes underlying vortex formations at different Knudsen numbers, Mach numbers, and cavity shapes are explicated. A parametric map that classifies different regimes of vortex structures as a function of compressibility, rarefaction, and cavity shape is developed.
我们研究并描述了可压缩性和稀释对基准顶盖驱动空腔流中涡旋结构的影响。我们采用统一气体动力学方案进行了直接数值模拟,研究了不同马赫数和克努森数下涡旋生成机制的变化以及由此产生的流动结构。在分子间相互作用最小的高稀释度下,分子主要与壁面碰撞。因此,主要的流动结构是空腔形状的单一漩涡。研究表明,由于分子间碰撞更加频繁,可压缩性增加或稀释度降低会导致空腔角落的分子密度增加。这导致流速降低,为次级涡旋和角涡旋的形成创造了有利条件。本文阐述了在不同的努森数、马赫数和空腔形状下形成涡旋的物理过程。还绘制了一张参数图,根据可压缩性、稀释和空腔形状的不同,对涡旋结构的不同状态进行分类。
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引用次数: 0
Some Equations in Rings Involving Semiprime Ideals and Multiplicative Generalized Semiderivations 环中涉及半等式和乘法广义半等式的一些方程
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-11 DOI: 10.3390/math12182818
Ali Yahya Hummdi, Öznur Gölbaşı, Emine Koç Sögütcü, Nadeem ur Rehman
This paper examines the commutativity of the quotient ring F/Y by utilizing specific differential identities in a general ring F that contains a semiprime ideal Y. This study particularly focuses on the role of a multiplicative generalized semiderivation ψ, which is associated with a map θ, in determining the commutative nature of the quotient ring.
本文利用包含一个半质理想 Y 的一般环 F 中的特定微分等式,研究了商环 F/Y 的交换性。本研究特别关注与映射 θ 相关联的乘法广义半矢量 ψ 在确定商环的交换性中的作用。
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引用次数: 0
Singularity, Observability, and Independence: Unveiling Lorenz’s Cryptographic Potential 奇异性、可观测性和独立性:揭示洛伦兹的密码学潜力
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-10 DOI: 10.3390/math12182798
Alexandru Dinu
The key findings of this study include a detailed examination of the Lorenz system’s observability, revealing that it maintains high observability compared to other chaotic systems, thus supporting its potential use in cryptographic applications. We also investigated the singularity manifolds, identifying regions where observability might be compromised, but overall demonstrating that the system remains reliable across various states. Additionally, statistical tests confirm that the Lorenz system exhibits strong statistical independence in its outputs, further validating its suitability for encryption purposes. These findings collectively underscore the Lorenz system’s potential to enhance cryptographic security and contribute significantly to the field of secure communications. By providing a thorough analysis of its key properties, this study positions the Lorenz system as a promising candidate for advanced encryption technologies.
本研究的主要发现包括对洛伦兹系统可观测性的详细研究,结果表明,与其他混沌系统相比,洛伦兹系统保持了较高的可观测性,因此支持其在密码学应用中的潜在用途。我们还研究了奇异性流形,确定了可观测性可能受到影响的区域,但总体上表明该系统在各种状态下都能保持可靠。此外,统计测试证实,洛伦兹系统的输出具有很强的统计独立性,这进一步验证了它在加密方面的适用性。这些发现共同强调了洛伦兹系统在提高密码安全性方面的潜力,并为安全通信领域做出了重大贡献。本研究通过对洛伦兹系统关键特性的全面分析,将其定位为先进加密技术的理想候选方案。
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引用次数: 0
A Novel Hybrid Model (EMD-TI-LSTM) for Enhanced Financial Forecasting with Machine Learning 利用机器学习增强金融预测的新型混合模型(EMD-TI-LSTM)
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-09 DOI: 10.3390/math12172794
Olcay Ozupek, Reyat Yilmaz, Bita Ghasemkhani, Derya Birant, Recep Alp Kut
Financial forecasting involves predicting the future financial states and performance of companies and investors. Recent technological advancements have demonstrated that machine learning-based models can outperform traditional financial forecasting techniques. In particular, hybrid approaches that integrate diverse methods to leverage their strengths have yielded superior results in financial prediction. This study introduces a novel hybrid model, entitled EMD-TI-LSTM, consisting of empirical mode decomposition (EMD), technical indicators (TI), and long short-term memory (LSTM). The proposed model delivered more accurate predictions than those generated by the conventional LSTM approach on the same well-known financial datasets, achieving average enhancements of 39.56%, 36.86%, and 39.90% based on the MAPE, RMSE, and MAE metrics, respectively. Furthermore, the results show that the proposed model has a lower average MAPE rate of 42.91% compared to its state-of-the-art counterparts. These findings highlight the potential of hybrid models and mathematical innovations to advance the field of financial forecasting.
财务预测涉及对公司和投资者未来财务状况和业绩的预测。最近的技术进步表明,基于机器学习的模型可以超越传统的财务预测技术。特别是,融合多种方法以发挥其优势的混合方法在金融预测方面取得了卓越的成果。本研究介绍了一种名为 EMD-TI-LSTM 的新型混合模型,该模型由经验模式分解(EMD)、技术指标(TI)和长短期记忆(LSTM)组成。基于 MAPE、RMSE 和 MAE 指标,在相同的知名金融数据集上,所提出的模型比传统 LSTM 方法生成的预测结果更准确,平均提升率分别为 39.56%、36.86% 和 39.90%。此外,结果表明,与最先进的模型相比,拟议模型的平均 MAPE 率更低,为 42.91%。这些发现凸显了混合模型和数学创新在推动金融预测领域发展方面的潜力。
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引用次数: 0
Prediction of Wind Turbine Gearbox Oil Temperature Based on Stochastic Differential Equation Modeling 基于随机微分方程建模的风力涡轮机齿轮箱油温预测
IF 2.4 3区 数学 Q1 MATHEMATICS Pub Date : 2024-09-09 DOI: 10.3390/math12172783
Hongsheng Su, Zonghao Ding, Xingsheng Wang
Aiming at the problem of high failure rate and inconvenient maintenance of wind turbine gearboxes, this paper establishes a stochastic differential equation model that can be used to fit the change of gearbox oil temperature and adopts an iterative computational method and Markov-based modified optimization to fit the prediction sequence in order to realize the accurate prediction of gearbox oil temperature. The model divides the oil temperature change of the gearbox into two parts, internal aging and external random perturbation, adopts the approximation theorem to establish the internal aging model, and uses Brownian motion to simulate the external random perturbation. The model parameters were calculated by the Newton–Raphson iterative method based on the gearbox oil temperature monitoring data. Iterative calculations and Markov-based corrections were performed on the model prediction data. The gearbox oil temperature variations were simulated in MATLAB, and the fitting and testing errors were calculated before and after the iterations. By comparing the fitting and testing errors with the ordinary differential equations and the stochastic differential equations before iteration, the iterated model can better reflect the gear oil temperature trend and predict the oil temperature at a specific time. The accuracy of the iterated model in terms of fitting and prediction is important for the development of preventive maintenance.
针对风电齿轮箱故障率高、维护不便的问题,本文建立了可用于拟合齿轮箱油温变化的随机微分方程模型,并采用迭代计算方法和基于马尔可夫的修正优化来拟合预测序列,以实现对齿轮箱油温的精确预测。该模型将变速箱油温变化分为内部老化和外部随机扰动两部分,采用近似定理建立内部老化模型,利用布朗运动模拟外部随机扰动。根据变速箱油温监测数据,采用牛顿-拉夫逊迭代法计算模型参数。对模型预测数据进行了迭代计算和基于马尔可夫的修正。在 MATLAB 中模拟了变速箱油温的变化,并计算了迭代前后的拟合误差和测试误差。通过比较迭代前与常微分方程和随机微分方程的拟合误差和测试误差,迭代后的模型能更好地反映齿轮油温度的变化趋势,并预测特定时间的油温。迭代模型在拟合和预测方面的准确性对预防性维护的发展非常重要。
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引用次数: 0
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