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Numerical Model Research on Rotational Performance of Beam-Column High-Strength Bolt Extension End-Plate Connection Node 梁柱高强螺栓端板连接节点转动性能的数值模型研究
Pub Date : 2021-05-21 DOI: 10.4236/ojmsi.2021.93015
Xiao Lang
The high-strength bolted end plate connection is widely used in the construction industry with its green environmental protection and excellent seismic performance. The joints of the joints are semi-rigid, the force performance is extremely complicated, and the experimental research cost is relatively high, and the cycle is very long. Therefore, the establishment of an efficient numerical model is of great significance for evaluating the force performance of high-strength bolt end plates. In this paper, the influence of different material models on the rotation performance of the joint is studied by numerical simulation, and the bending moment-rotation curve is obtained. The numerical simulation and the experimental results are in good agreement, so as to provide a reference for the design and application of this kind of joint.
高强度螺栓端板连接以其绿色环保、抗震性能优异而广泛应用于建筑行业。接头的接头为半刚性,受力性能极其复杂,实验研究成本相对较高,周期很长。因此,建立高效的数值模型对于评估高强螺栓端板受力性能具有重要意义。本文通过数值模拟研究了不同材料模型对接头转动性能的影响,得到了接头的弯矩-转动曲线。数值模拟结果与实验结果吻合较好,为该类接头的设计和应用提供参考。
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引用次数: 0
A Comparison of Deterministic and Stochastic Susceptible-Infected-Susceptible (SIS) and Susceptible-Infected-Recovered (SIR) Models 确定性和随机易感-感染-易感(SIS)和易感-感染-恢复(SIR)模型的比较
Pub Date : 2021-05-21 DOI: 10.4236/ojmsi.2021.93016
A. Moujahid, F. Vadillo
In this paper we build and analyze two stochastic epidemic models with death. The model assumes that only susceptible individuals (S) can get infected (I) and may die from this disease or a recovered individual becomes susceptible again (SIS model) or completely immune (SIR Model) for the remainder of the study period. Moreover, it is assumed there are no births, deaths, immigration or emigration during the study period; the community is said to be closed. In these infection disease models, there are two central questions: first it is the disease extinction or not and the second studies the time elapsed for such extinction, this paper will deal with this second question because the first answer corresponds to the basic reproduction number defined in the bibliography. More concretely, we study the mean-extinction of the diseases and the technique used here first builds the backward Kolmogorov differential equation and then solves it numerically using finite element method with FreeFem++. Our contribution and novelty are the following: however the reproduction number effectively concludes the extinction or not of the disease, it does not help to know its extinction times because example with the same reproduction numbers has very different time. Moreover, the SIS model is slower, a result that is not surprising, but this difference seems to increase in the stochastic models with respect to the deterministic ones, it is reasonable to assume some uncertainly.
本文建立并分析了两个有死亡的随机流行病模型。该模型假设只有易感个体(S)才会感染(I)并可能死于这种疾病,或者恢复后的个体再次易感(SIS模型)或在剩余的研究期间完全免疫(SIR模型)。此外,假定在研究期间没有出生、死亡、移民或移民;据说该社区已经关闭。在这些传染病模型中,有两个中心问题:第一是疾病是否灭绝,第二是研究这种灭绝所经过的时间,本文将处理第二个问题,因为第一个答案对应于参考书目中定义的基本繁殖数。更具体地说,我们研究了疾病的平均灭绝,这里使用的技术首先建立倒向Kolmogorov微分方程,然后用FreeFem++进行数值求解。我们的贡献和新颖之处在于:尽管繁殖数有效地判断了疾病的灭绝与否,但它并不能帮助我们知道疾病的灭绝时间,因为相同繁殖数的例子有非常不同的时间。此外,SIS模型较慢,这一结果并不令人惊讶,但相对于确定性模型,这种差异似乎在随机模型中有所增加,假设一些不确定性是合理的。
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引用次数: 1
Probabilistic Modelling of COVID-19 Dynamic in the Context of Madagascar 马达加斯加地区COVID-19动态概率建模
Pub Date : 2021-05-21 DOI: 10.4236/OJMSI.2021.93014
Angelo Raherinirina, Tsilefa Stefana Fandresena, A. R. Hajalalaina, H. Rabetafika, R. Rakotoarivelo, Fontaine Rafamatanantsoa
We propose a probabilistic approach to modelling the propagation of the coronavirus disease 2019 (COVID-19) in Madagascar, with all its specificities. With the strategy of the Malagasy state, which consists of isolating all suspected cases and hospitalized confirmed case, we get an epidemic model with seven compartments: susceptible (S), Exposed (E), Infected (I), Asymptomatic (A), Hospitalized (H), Cured (C) and Death (D). In addition to the classical deterministic models used in epidemiology, the stochastic model offers a natural representation of the evolution of the COVID-19 epidemic. We inferred the models with the official data provided by the COVID-19 Command Center (CCO) of Madagascar, between March and August 2020. The basic reproduction number R0 and the other parameters were estimated with a Bayesian approach. We developed an algorithm that allows having a temporal estimate of this number with confidence intervals. The estimated values are slightly lower than the international references. Generally, we were able to obtain a simple but effective model to describe the spread of the disease.
我们提出了一种概率方法来模拟2019年冠状病毒病(COVID-19)在马达加斯加的传播及其所有特异性。根据马达加斯加国家隔离所有疑似病例和住院确诊病例的策略,我们得到了一个由七个隔间组成的流行病模型:易感(S)、暴露(E)、感染(I)、无症状(A)、住院(H)、治愈(C)和死亡(D)。除了流行病学中使用的经典确定性模型外,随机模型还提供了COVID-19流行病演变的自然表征。我们根据2020年3月至8月马达加斯加COVID-19指挥中心(CCO)提供的官方数据推断了这些模型。用贝叶斯方法估计了基本繁殖数R0和其他参数。我们开发了一种算法,可以对这个数字进行具有置信区间的时间估计。估计值略低于国际参考值。总的来说,我们能够得到一个简单而有效的模型来描述疾病的传播。
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引用次数: 5
A New Mathematical Modeling of the COVID-19 Pandemic Including the Vaccination Campaign 包括疫苗接种运动在内的新型COVID-19大流行数学模型
Pub Date : 2021-05-21 DOI: 10.4236/ojmsi.2021.93020
M. Yavuz, Fatma Özlem Coşar, Fatma Günay, F. Özdemi̇r
In a short time, many illustrative studies have been conducted on the mathematical modeling and analysis of COVID-19. There are not enough studies taking into account the vaccine campaign among these studies. In this context, a mathematical model is developed to reveal the effects of vaccine treatment, which has been performed recently, on COVID-19 in this study. In the proposed model, as well as the vaccinated individuals, a five-dimensional compartment system including the susceptible, infected, exposed and recovered population is constructed. Moreover, besides the positivity, existence and uniqueness of the solution, biologically feasible region are provided. The basic reproduction number known as expected secondary infection which means that expected infection among the susceptible populations caused by this infection is evaluated. In the numerical simulations, the parameter values taken from the literature and estimated are used to perform the solutions of the proposed model. Fourth-order Runge-Kutta numerical scheme is applied to obtain the results.
在短时间内,对新冠肺炎的数学建模和分析进行了许多说明性研究。在这些研究中,没有足够的研究考虑到疫苗运动。在此背景下,本研究开发了一个数学模型,以揭示最近进行的疫苗治疗对新冠肺炎的影响。在所提出的模型中,以及接种疫苗的个体,构建了一个包括易感人群、感染人群、暴露人群和康复人群的五维隔间系统。此外,除了解的正性、存在性和唯一性之外,还提供了生物学上可行的区域。被称为预期二次感染的基本繁殖数,这意味着对由这种感染引起的易感人群中的预期感染进行评估。在数值模拟中,使用从文献中获得的参数值和估计值来执行所提出的模型的求解。应用四阶龙格-库塔数值格式得到了结果。
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引用次数: 47
Mathematical Model and Non-Pharmaceutical Control of the Coronavirus 2019 Disease in Madagascar 马达加斯加2019冠状病毒病的数学模型和非药物控制
Pub Date : 2021-05-21 DOI: 10.4236/ojmsi.2021.93017
Angelo Raherinirina, Fontaine Rafamatanantsoa, Tsilefa Stefana Fandresena, R. Rakotoarivelo
For Madagascar, with the uncertainty over vaccines against the novel coronavirus 2019 and its variants, non-pharmaceutical approach is widely used. Our objective is to propose a mathematical control model which will serve as a tool to help decision-makers in the strategy to be implemented to better face the pandemic. By separating asymptomatic cases which are often not reported and symptomatic who are hospitalized after tests; we develop a mathematical model of the propagation of covid-19 in Madagascar, by integrating control strategies. We study the stability of the model by expressing the basic reproduction number using the next-generation matrix. Simulation with different parameters shows the effects of non-pharmaceutical measures on the speed of the disease spread. By integrating a control parameter linked to compliance with barrier measures in the virus propagation equation, we were able to show the impacts of the implementation of social distancing measures on the basic reproduction number. The strict application of social distancing measures and total confinement is unfavorable for economic situation even if they allow the contamination to be reduced quickly. Without any restrictions, the disease spreads at high speed and the peak is reached fairly quickly. In this condition, hospitals are overwhelmed and the death rate increases rapidly. With 50% respect for non-pharmaceutical strategies such as rapid detection and isolation of positive cases and barrier gestures; the basic reproduction number R0 can go down from 3 to 1.7. The pressures on the economic and social situation are rather viable. It is the most suitable for the Malagasy health system. The results proposed are a way to control the spread of the disease and limit its devastation in a country like Madagascar.
对于马达加斯加来说,由于针对2019年新型冠状病毒及其变种的疫苗存在不确定性,因此广泛使用非药物方法。我们的目标是提出一个数学控制模型,该模型将作为一种工具,帮助决策者更好地应对这一流行病。将通常未报告的无症状病例与检测后住院的有症状病例分开;通过整合控制策略,我们建立了covid-19在马达加斯加传播的数学模型。我们用新一代矩阵表示基本繁殖数来研究模型的稳定性。用不同参数的模拟显示了非药物措施对疾病传播速度的影响。通过在病毒传播方程中整合与遵守隔离措施相关的控制参数,我们能够显示实施社交距离措施对基本繁殖数的影响。严格实行保持社会距离和全面隔离措施,即使能迅速减少污染,也不利于经济形势。在没有任何限制的情况下,疾病传播速度很快,达到高峰的速度也相当快。在这种情况下,医院不堪重负,死亡率迅速上升。50%尊重非药物战略,如快速发现和隔离阳性病例和屏障手势;基本繁殖数R0可以从3下降到1.7。对经济和社会形势的压力是相当可行的。这是最适合马达加斯加卫生系统的。提出的结果是一种控制疾病传播并限制其在马达加斯加这样的国家造成破坏的方法。
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引用次数: 1
Research on Vertical Bearing Capacity of Pile Foundation under Wave Scouring 波浪冲刷作用下桩基竖向承载力研究
Pub Date : 2021-04-15 DOI: 10.4236/OJMSI.2021.92008
Xinyue Wang
In order to analyze the influence of wave scouring on the vertical bearing behavior of the pile foundation, the finite element software ABAQUS was used to simulate the force of the pile foundation under the action of wave scouring. A three-dimensional finite element calculation model of the pile foundation was established according to the actual working conditions, and the calculation results were compared with the field test results to verify the correctness of the built model. Then, the influence of wave scouring depth and pile embedding depth on the vertical bearing behavior of pile foundation was analyzed through calculation examples. The analysis results showed that the greater the depth of wave erosion, the greater the impact on the vertical bearing behavior of the pile foundation. Meanwhile, the smaller the buried depth of the pile body, the greater the impact on the vertical bearing capacity of the pile. Thus, the reduction rate of the vertical bearing capacity under different scouring depths was obtained.
为了分析波浪冲刷对桩基竖向承载性能的影响,利用有限元软件ABAQUS对波浪冲刷作用下的桩基受力进行了模拟。根据实际工况建立了桩基的三维有限元计算模型,并将计算结果与现场试验结果进行了比较,验证了所建模型的正确性。通过算例分析了波浪冲刷深度和桩埋深对桩基竖向承载性能的影响。分析结果表明,波浪冲刷深度越大,对桩基竖向承载性能的影响越大。同时,桩身埋深越小,对桩竖向承载力的影响越大。从而得出了不同冲刷深度下的竖向承载力折减率。
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引用次数: 1
Mathematical Modelling of the COVID-19 Epidemic in Northern Ireland in 2020 2020年北爱尔兰COVID-19流行的数学模型
Pub Date : 2021-04-09 DOI: 10.4236/OJMSI.2021.92006
P. Hall, G. Kiss, Tilmann E. Kuhn, S. Moutari, E. Patterson, Emily R. Smith
In this study, we investigate the dynamics of the COVID-19 epidemic in Northern Ireland from 1st March 2020 up to 25th December 2020, using several copies of a Susceptible-Exposed-Infectious-Recovered (SEIR) compartmental model, and compare it to a detailed publicly available dataset. We split the data into 10 time intervals and fit the models on the consecutive intervals to the cumulative number of confirmed positive cases on each interval. Using the fitted parameter estimates, we also provide estimates of the reproduction number. We also discuss the limitations and possible extensions of the employed model.
在本研究中,我们研究了2020年3月1日至2020年12月25日北爱尔兰COVID-19流行的动态,使用了易感-暴露-感染-恢复(SEIR)分区模型的几个副本,并将其与详细的公开数据集进行了比较。我们将数据分成10个时间间隔,并将连续间隔上的模型拟合为每个间隔上的累计确诊阳性病例数。利用拟合参数估计,我们还提供了再现数的估计。我们还讨论了所采用模型的局限性和可能的扩展。
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引用次数: 0
DecPDEVS: New Simulation Algorithms to Improve Message Handling in PDEVS DecPDEVS:改进PDEVS中消息处理的新仿真算法
Pub Date : 2021-04-09 DOI: 10.4236/OJMSI.2021.92012
P. Bisgambiglia, P. Bisgambiglia
This work proposes a new simulation algorithm to improve message handling in discrete event formalism. We present an approach to minimize simulation execution time. To do this, we propose to reduce the number of exchanged messages between Parallel DEVS (PDEVS) components (simulators and coordinators). We propose three changes from PDEVS: direct coupling, flat structure and local schedule. The goal is the decentralisation of a number of tasks to make the simulators more autonomous and simplify the coordinators to achieve a greater speedup. We propose to compare the simulation results of several models to demonstrate the benefits of our approach.
本文提出了一种新的模拟算法来改进离散事件形式中的消息处理。我们提出了一种最小化模拟执行时间的方法。为此,我们建议减少并行DEVS(PDEVS)组件(模拟器和协调器)之间交换的消息数量。我们提出了PDEVS的三个变化:直接耦合、扁平结构和局部时间表。目标是分散一些任务,使模拟器更加自主,并简化协调器,以实现更大的加速。我们建议比较几个模型的模拟结果,以证明我们的方法的好处。
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引用次数: 1
Worker’s Helmet Recognition and Identity Recognition Based on Deep Learning 基于深度学习的工人头盔识别与身份识别
Pub Date : 2021-04-09 DOI: 10.4236/OJMSI.2021.92009
Jie Wang, Guangzu Zhu, Shiqi Wu, Chunshan Luo
For decades, safety has been a concern for the construction industry. Helmet detection caught the attention of machine learning, but the problem of identity recognition has been ignored in previous studies, which brings trouble to the subsequent safety education of workers. Although, many scholars have devoted themselves to the study of person re-identification which neglected safety detection. The study of this paper mainly proposes a method based on deep learning, which is different from the previous study of helmet detection and human identity recognition and can carry out helmet detection and identity recognition for construction workers. This paper proposes a computer vision-based worker identity recognition and helmet recognition method. We collected 3000 real-name channel images and constructed a neural network based on the You Only Look Once (YOLO) v3 model to extract the features of the construction worker’s face and helmet, respectively. Experiments show that the method has a high recognition accuracy rate, fast recognition speed, accurate recognition of workers and helmet detection, and solves the problem of poor supervision of real-name channels.
几十年来,安全一直是建筑业关注的问题。头盔检测引起了机器学习的注意,但在以往的研究中,身份识别问题一直被忽视,这给后续的工人安全教育带来了麻烦。尽管如此,许多学者致力于人的再识别研究,忽视了安全检测。本文的研究主要提出了一种基于深度学习的方法,该方法不同于以往对头盔检测和人体身份识别的研究,可以对建筑工人进行头盔检测和身份识别。本文提出了一种基于计算机视觉的工人身份识别和头盔识别方法。我们收集了3000张实名通道图像,并基于YOLO v3模型构建了一个神经网络,分别提取建筑工人的面部和头盔特征。实验表明,该方法识别准确率高,识别速度快,对工作人员和头盔检测识别准确,解决了实名通道监管不力的问题。
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引用次数: 6
A Short Review on Computational Hydraulics in the context of Water Resources Engineering 水利工程背景下的计算水力学简评
Pub Date : 2021-02-24 DOI: 10.31224/osf.io/t4bne
S. Sarker
The term hydraulics concerned with the conveyance of water that can consist of very simple processes to complex physical processes, such as flow in open rivers, flow in pipes, flow of nutrients/sediments, flow of ground water to sea waves. The study of hydraulics is primarily a mixture of theory and experiments. Computational hydraulics is very helpful in-order to quantify and predict flow nature and behavior. Mathematical model is backbone of the computational hydraulics that consist simple to complex mathematical equations with linear and/or non-linear terms and ordinary or partial differential equations. Analytical solution of this mathematical equations is not feasible in the majority of cases. In this consequences, mathematical models are solved using different numerical techniques and associated schemes. In this manuscript we will review hydraulic principles along with their mathematical equations. Then we will learn some commonly used numerical technique to solve different types of differential equations related to the hydraulics. Among them the Finite Difference Method (FDM), Finite Element Method (FEM) and Finite Volume Method (FVM) will be discussed along with their use in real-life applications in the context of water resources engineering.
水力学一词涉及水的输送,可以由非常简单的过程到复杂的物理过程组成,如开放河流中的流动、管道中的流动,营养物质/沉积物的流动,地下水到海浪的流动。水力学的研究主要是理论和实验的结合。计算水力学对于量化和预测流动性质和行为非常有用。数学模型是计算水力学的支柱,它包括具有线性和/或非线性项的简单到复杂的数学方程以及常微分方程或偏微分方程。这种数学方程的解析解在大多数情况下是不可行的。因此,使用不同的数值技术和相关方案来求解数学模型。在这份手稿中,我们将回顾水力学原理及其数学方程。然后我们将学习一些常用的数值技术来求解与水力学相关的不同类型的微分方程。其中,将讨论有限差分法(FDM)、有限元法(FEM)和有限体积法(FVM)及其在水利工程实际应用中的应用。
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引用次数: 16
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