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Developing a Numerical Method of Risk Management Taking into Account the Decision-Maker's Subjective Attitude Towards Multifactorial Risks 考虑决策者对多因素风险主观态度的风险管理数值方法
Pub Date : 2023-07-05 DOI: 10.3390/computation11070132
Aleksandr Alekseev, Z. Mingaleva, I. Alekseeva, E. Lobova, Alexander Oksman, Alexander Mitrofanov
Risk involves identifying several options that the decision-maker can opt for while making a choice either in the direction of risk or reliability. In this approach, risk is defined as the action of the subject which will lead to the loss or guaranteed safety of what has been achieved. As the uncertainty of the external business environment increases for companies, the task of managing risks both individually and as a set of risks becomes more and more relevant. The purpose of this study is to solve the problem of managing multifactorial risks using mathematical methods for determining the optimal risk management trajectories separately for each factor. To determine the optimal risk management trajectories for each factor, a numerical method is used based on the choice of the most effective direction, which is defined as the ratio of risk change to cost change. An information system prototype has been created that can support the management of a set of risks. Approbation of the information system was carried out on an example containing two conceptual risk factors. The proposed prototype builds a three-dimensional risk map by interpolating the risk matrix entered by the risk manager using an additive–multiplicative aggregation procedure, as well as optimal risk management trajectories for all entered risk factors.
风险包括确定决策者在选择风险或可靠性方向时可以选择的几个选项。在这种方法中,风险被定义为主体的行为,这种行为将导致已经取得的成果的损失或已保证的安全。随着外部商业环境的不确定性对公司的增加,管理风险的任务无论是单独的还是作为一组风险变得越来越重要。本研究的目的是解决多因素风险管理问题,使用数学方法分别确定每个因素的最佳风险管理轨迹。为了确定每个因素的最佳风险管理轨迹,采用了一种基于选择最有效方向的数值方法,该方向定义为风险变化与成本变化的比值。已经创建了可以支持一组风险管理的信息系统原型。对信息系统的认可是基于一个包含两个概念性风险因素的例子。提出的原型通过使用加乘聚合过程插值风险管理器输入的风险矩阵来构建三维风险图,并为所有输入的风险因素构建最佳风险管理轨迹。
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引用次数: 0
Analytical Solution and Numerical Simulation of Heat Transfer in Cylindrical- and Spherical-Shaped Bodies 圆柱形和球形物体传热的解析解和数值模拟
Pub Date : 2023-07-05 DOI: 10.3390/computation11070131
H. Jalghaf, Endre Kovács, I. F. Barna, László Mátyás
New analytical solutions of the heat conduction equation obtained by utilizing a self-similar Ansatz are presented in cylindrical and spherical coordinates. Then, these solutions are reproduced with high accuracy using recent explicit and unconditionally stable finite difference methods. After this, real experimental data from the literature regarding a heated cylinder are reproduced using the explicit numerical methods as well as using Finite Element Methods (FEM) ANSYS workbench. Convection and nonlinear radiation are also considered on the boundary of the cylinder. The verification results showed that the numerical methods have a high accuracy to deal with cylindrical and spherical bodies; also, the comparison of the temperatures for all approaches showed that the explicit methods are more accurate than the commercial software.
利用自相似的Ansatz给出了在柱坐标和球坐标下新的热传导方程解析解。然后,利用最近的显式无条件稳定有限差分方法,高精度地再现了这些解。在此之后,使用显式数值方法以及有限元方法(FEM) ANSYS工作台再现了文献中关于加热圆柱体的真实实验数据。柱体边界上还考虑了对流和非线性辐射。验证结果表明,该数值方法对圆柱体和球面体均具有较高的精度;同时,对各种方法的温度进行了比较,表明显式方法比商业软件更准确。
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引用次数: 0
Special Issue "Advances in Machine and Deep Learning in the Health Domain" 特刊“健康领域机器和深度学习的进展”
Pub Date : 2023-07-04 DOI: 10.3390/computers12070135
A. Celesti, I. D. Falco, A. Galletta, Giovanna Sannino
Machine and deep learning techniques are fuelling a revolution in the health domain and are attracting the interest of many cross-disciplinary research groups all over the world [...]
机器和深度学习技术正在推动健康领域的革命,并吸引了世界各地许多跨学科研究小组的兴趣[…]
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引用次数: 0
Applications of Modified Bessel Polynomials to Solve a Nonlinear Chaotic Fractional-Order System in the Financial Market: Domain-Splitting Collocation Techniques 修正贝塞尔多项式在求解金融市场非线性混沌分数阶系统中的应用:域分裂配置技术
Pub Date : 2023-07-03 DOI: 10.3390/computation11070130
M. Izadi, H. M. Srivastava
We propose two accurate and efficient spectral collocation techniques based on a (novel) domain-splitting strategy to handle a nonlinear fractional system consisting of three ODEs arising in financial modeling and with chaotic behavior. One of the major numerical difficulties in designing traditional spectral methods is in the handling of model problems on a long computational domain, which usually yields to loss of accuracy. One remedy is to split the underlying domain and apply the spectral method locally in each subdomain rather than on the global domain of interest. To treat the chaotic financial system numerically, we use the generalized version of modified Bessel polynomials (GMBPs) in the collocation matrix approaches along with the domain-splitting strategy. Whereas the first matrix collocation scheme is directly applied to the financial model problem, the second one is a combination of the quasilinearization method and the direct first numerical matrix method. In the former approach, we arrive at nonlinear algebraic matrix equations while the resulting systems are linear in the latter method and can be solved more efficiently. A convergence theorem related to GMBPs is proved and an upper bound for the error is derived. Several simulation outcomes are provided to show the utility and applicability of the presented matrix collocation procedures.
针对金融建模中出现的具有混沌行为的由三个ode组成的非线性分数系统,提出了基于(新颖的)域分裂策略的两种准确高效的谱配置技术。设计传统谱方法的主要数值困难之一是在长计算域上处理模型问题,这通常会导致精度的损失。一种补救方法是拆分底层域,并在每个子域局部应用谱方法,而不是在感兴趣的全局域上应用谱方法。为了对混沌金融系统进行数值处理,我们在搭配矩阵方法中使用广义修正贝塞尔多项式(GMBPs),并结合域分裂策略。第一种矩阵配置方案直接应用于金融模型问题,第二种矩阵配置方案是拟线性化方法与直接第一数值矩阵方法的结合。在前一种方法中,我们得到非线性代数矩阵方程,而在后一种方法中得到的系统是线性的,可以更有效地求解。证明了GMBPs的一个收敛定理,并给出了误差的上界。仿真结果表明了所提出的矩阵配置方法的实用性和适用性。
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引用次数: 2
Computation of the Exact Forms of Waves for a Set of Differential Equations Associated with the SEIR Model of Epidemics 与SEIR流行病模型相关的一组微分方程波的精确形式的计算
Pub Date : 2023-07-02 DOI: 10.3390/computation11070129
N. Vitanov, Z. Dimitrova
We studied obtaining exact solutions to a set of equations related to the SEIR (Susceptible-Exposed-Infectious-Recovered) model of epidemic spread. These solutions may be used to model epidemic waves. We transformed the SEIR model into a differential equation that contained an exponential nonlinearity. This equation was then approximated by a set of differential equations which contained polynomial nonlinearities. We solved several equations from the set using the Simple Equations Method (SEsM). In doing so, we obtained many new exact solutions to the corresponding equations. Several of these solutions can describe the evolution of epidemic waves that affect a small percentage of individuals in the population. Such waves have frequently been observed in the COVID-19 pandemic in recent years. The discussion shows that SEsM is an effective methodology for computing exact solutions to nonlinear differential equations. The exact solutions obtained can help us to understand the evolution of various processes in the modeled systems. In the specific case of the SEIR model, some of the exact solutions can help us to better understand the evolution of the quantities connected to the epidemic waves.
我们研究了流行病传播的SEIR(易感-暴露-感染-恢复)模型的一组方程的精确解。这些解决方案可用于模拟流行病波。我们将SEIR模型转化为包含指数非线性的微分方程。然后用一组包含多项式非线性的微分方程来近似这个方程。我们用简单方程法(SEsM)从集合中求解了几个方程。通过这样做,我们得到了相应方程的许多新的精确解。其中一些解决方案可以描述影响人口中一小部分个体的流行病波的演变。近年来,在COVID-19大流行中经常观察到这种波动。讨论表明,SEsM是计算非线性微分方程精确解的有效方法。得到的精确解可以帮助我们理解模型系统中各种过程的演化。在SEIR模型的具体案例中,一些精确的解可以帮助我们更好地理解与流行病波相关的量的演变。
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引用次数: 2
Technologies Supporting Screening Oculomotor Problems: Challenges for Virtual Reality 支持筛选眼动问题的技术:对虚拟现实的挑战
Pub Date : 2023-07-01 DOI: 10.3390/computers12070134
Are Dæhlen, I. Heldal, Qasim Ali
Oculomotor dysfunctions (OMDs) are problems relating to coordination and accuracy of eye movements for processing visual information. Eye-tracking (ET) technologies show great promise in the identification of OMDs. However, current computer technologies for vision screening are specialized devices with limited screen size and the inability to measure depth, while visual field and depth are important information for detecting OMDs. In this experimental study, we examine the possibilities of immersive virtual reality (VR) technologies compared with laptop technologies for increased user experiences, presence, immersiveness, and the use of serious games for identifying OMDs. The results present increased interest in VR-based screening, motivating users to focus better using VR applications free from outside distractions. These limitations currently include lower performance and confidence in results of identifying OMDs with the used HMDs. Using serious games for screening in VR is also estimated to have great potential for developing a more robust vision screening tool, especially for younger children.
眼动功能障碍(OMDs)是一种与处理视觉信息时眼球运动的协调性和准确性有关的问题。眼动追踪(ET)技术在识别眼动障碍方面显示出巨大的前景。然而,目前用于视觉筛查的计算机技术是专门的设备,屏幕尺寸有限,无法测量深度,而视野和深度是检测omd的重要信息。在这项实验研究中,我们研究了沉浸式虚拟现实(VR)技术与笔记本电脑技术相比,在增加用户体验、存在感、沉浸感和使用严肃游戏来识别omd方面的可能性。结果显示,人们对基于VR的筛选越来越感兴趣,这促使用户在不受外界干扰的情况下更好地使用VR应用程序。这些限制目前包括较低的性能和对使用的hmd识别omd结果的置信度。据估计,在VR中使用严肃游戏进行筛查也有很大的潜力,可以开发出更强大的视力筛查工具,特别是针对年幼的儿童。
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引用次数: 0
Response Spectrum Analysis of Multi-Story Shear Buildings Using Machine Learning Techniques 基于机器学习技术的多层剪力结构反应谱分析
Pub Date : 2023-06-29 DOI: 10.3390/computation11070126
Manolis Georgioudakis, V. Plevris
The dynamic analysis of structures is a computationally intensive procedure that must be considered, in order to make accurate seismic performance assessments in civil and structural engineering applications. To avoid these computationally demanding tasks, simplified methods are often used by engineers in practice, to estimate the behavior of complex structures under dynamic loading. This paper presents an assessment of several machine learning (ML) algorithms, with different characteristics, that aim to predict the dynamic analysis response of multi-story buildings. Large datasets of dynamic response analyses results were generated through standard sampling methods and conventional response spectrum modal analysis procedures. In an effort to obtain the best algorithm performance, an extensive hyper-parameter search was elaborated, followed by the corresponding feature importance. The ML model which exhibited the best performance was deployed in a web application, with the aim of providing predictions of the dynamic responses of multi-story buildings, according to their characteristics.
为了在土木和结构工程应用中做出准确的抗震性能评估,结构的动力分析是一个必须考虑的计算密集型过程。为了避免这些计算要求很高的任务,工程师在实践中经常使用简化的方法来估计复杂结构在动荷载作用下的行为。本文对几种具有不同特征的机器学习(ML)算法进行了评估,这些算法旨在预测多层建筑的动态分析响应。通过标准抽样方法和常规的响应谱模态分析程序生成了大型动态响应分析结果数据集。为了获得最佳的算法性能,详细阐述了一个广泛的超参数搜索,然后是相应的特征重要度。将表现出最佳性能的ML模型部署到web应用程序中,目的是根据多层建筑的特征提供动态响应的预测。
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引用次数: 3
Stefan Blowing Impacts on Hybrid Nanofluid Flow over a Moving Thin Needle with Thermal Radiation and MHD 基于热辐射和MHD的Stefan吹气对移动细针上混合纳米流体流动的影响
Pub Date : 2023-06-29 DOI: 10.3390/computation11070128
V. S. Reddy, Jagan Kandasamy, S. Sivanandam
This investigation focuses on the impact of Stefan blowing on the flow of hybrid nanoliquids over a moving slender needle with magnetohydrodynamics (MHD), thermal radiation, and entropy generation. To facilitate analysis, suitable transformations are applied to convert the governing partial differential equations into a set of ordinary differential equations, which are then solved analytically using Homotopy Analysis Method (HAM) in Mathematica. This study investigates how varying the values of Stefan blowing, magnetic field, and thermal radiation parameters impact the profiles of velocity, temperature, and concentration. Additionally, the study analyzes the outcomes of the local skin friction, local Nusselt number, and local Sherwood number. Increasing the magnetic field reduces the velocity profile. The temperature profile is enhanced by a rise in the thermal radiation parameter. Also, the results reveal that an increase in the Stefan blowing number leads to higher profiles of velocity.
利用磁流体动力学(MHD)、热辐射和熵产研究了Stefan吹气对混合纳米液体在移动细针上流动的影响。为了便于分析,采用适当的变换将控制偏微分方程转化为一组常微分方程,然后使用Mathematica中的同伦分析方法(HAM)对其进行解析求解。本研究探讨了风机吹风、磁场和热辐射参数的变化对速度、温度和浓度分布的影响。此外,本研究还分析了局部皮肤摩擦、局部努塞尔数和局部舍伍德数的结果。增大磁场会减小速度分布。温度分布由于热辐射参数的升高而增强。此外,结果表明,斯特凡吹数的增加导致更高的速度剖面。
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引用次数: 1
Mixed Cultural Visits or What COVID-19 Taught Us 混合文化访问或COVID-19教给我们什么
Pub Date : 2023-06-29 DOI: 10.20944/preprints202305.0919.v1
Angeliki Antoniou
When the majority of museums and other cultural institutions were shut down due to the pandemic, mixed museum visits became a hot issue. After the pandemic, mixed visits, in the opinion of many experts, would become the new norm for experiencing cultural content. Diverse types of mergers between online and onsite visits have already begun to be investigated by researchers, with the purpose of not only avoiding the spread of disease but also of enabling visits of people who were previously excluded, such as persons in remote geographic areas or people with mobility challenges. In fact, over the last three years, there have been rapid developments in mixed visits in cultural heritage sites. The current work takes into account a contextual model of museum learning to define potential use scenarios for visits from people of different cultural backgrounds and offers an evaluation of current practices. The new model that emerges, the contextual model of mixed visits, allows for the further study of the field, as it attempts to describe recent research efforts in four main contexts: mixed visits in the personal context, mixed visits in the socio-cultural context, mixed visits in the physical context, and temporality of mixed visits. Inductive analysis of a literature review allowed the extraction of relevant themes, examples from museums, as well as extraction of guidelines.
当大多数博物馆和其他文化机构因疫情而关闭时,混合博物馆参观成为一个热点问题。许多专家认为,疫情过后,混合访问将成为体验文化内容的新常态。研究人员已经开始调查在线访问和现场访问之间的各种合并形式,其目的不仅是避免疾病传播,而且是使以前被排除在外的人能够访问,例如偏远地区的人或行动不便的人。事实上,在过去的三年里,文化遗产的混合参观有了快速的发展。目前的工作考虑到博物馆学习的语境模型,以定义不同文化背景的人访问的潜在使用场景,并对当前的实践进行评估。出现的新模型,混合访问的上下文模型,允许对该领域进行进一步研究,因为它试图描述最近在四个主要背景下的研究成果:个人背景下的混合访问,社会文化背景下的混合访问,物理背景下的混合访问,以及混合访问的时间性。文献综述的归纳分析允许提取相关主题,从博物馆的例子,以及提取指南。
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引用次数: 0
Analytical and Numerical Results for the Diffusion-Reaction Equation When the Reaction Coefficient Depends on Simultaneously the Space and Time Coordinates 反应系数同时依赖于时空坐标时扩散-反应方程的解析和数值结果
Pub Date : 2023-06-29 DOI: 10.3390/computation11070127
A. Askar, A. Nagy, I. F. Barna, Endre Kovács
We utilize the travelling-wave Ansatz to obtain novel analytical solutions to the linear diffusion–reaction equation. The reaction term is a function of time and space simultaneously, firstly in a Lorentzian form and secondly in a cosine travelling-wave form. The new solutions contain the Heun functions in the first case and the Mathieu functions for the second case, and therefore are highly nontrivial. We use these solutions to test some non-conventional explicit and stable numerical methods against the standard explicit and implicit methods, where in the latter case the algebraic equation system is solved by the preconditioned conjugate gradient and the GMRES solvers. After this verification, we also calculate the transient temperature of a 2D surface subjected to the cooling effect of the wind, which is a function of space and time again. We obtain that the explicit stable methods can reach the accuracy of the implicit solvers in orders of magnitude shorter time.
我们利用行波Ansatz得到了线性扩散反应方程的新的解析解。反应项同时是时间和空间的函数,首先是洛伦兹形式,其次是余弦行波形式。新解包含第一种情况下的Heun函数和第二种情况下的Mathieu函数,因此具有高度的非平凡性。我们利用这些解对标准显式和隐式方法进行了一些非常规的显式和稳定数值方法的测试,在标准显式和隐式方法中,后一种情况下的代数方程组是用预条件共轭梯度和GMRES求解器求解的。在此验证之后,我们还计算了受风冷却作用的二维表面的瞬态温度,该温度再次是空间和时间的函数。结果表明,显式稳定方法可以在较短的时间内达到隐式求解方法的数量级精度。
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引用次数: 2
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Comput.
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