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Colored Petri Net-Based Verification and Improvement of Time-Sensitive Single-Unit Manufacturing for the Soil Preparation Instrument of Space Missions (2020)

Yung, Kai Leung ; Gao, Ming ; Liu, An ; [et al.]

Hindawi

In: Discrete Dynamics in Nature and Society. 2020; 2020: 1-18. Published 2020 Aug 25. doi: 10.1155/2020/2162869.

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Publication Date: 2020-08-25

Description: Various space missions, including the Russian and Chinese interplanetary exploration collaboration in 2011 and the Phobos-Grunt space project to be relaunched by the Chinese in 2025, carry a soil preparation system (SOPSYS), which is an instrument used for scientific experiments. The design and manufacture of this precision instrument require stringent manufacturing processes and workflow of the highest quality, with every process in the project carefully monitored and controlled. All processes should be completed within the deadline so that the space project can be launched at the scheduled time. The colored Petri net (CPN) modeling method can describe a variety of resource types and execution logic, and it can be formally verified. Based on these advantages, we clearly describe the complex structure of the SPOSYS unit production process. In addition, we use critical time and the 6 sigma system to evaluate the availability and reliability of workflows, and we use elimination and simplification (ECRS) methods and constraint theory to improve the manufacturing process of the SOPSYS unit. We further provide optimization theories, methods, and insights for workflow management in time-sensitive and independent manufacturing systems.

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Electronic ISSN: 1607-887X

Topics: Mathematics

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Stability of a Discrete-Time Pathogen Infection Model with Adaptive Immune Response (2020)

Alshaikh, M. A. ; Elaiw, A. M.

Hindawi

In: Discrete Dynamics in Nature and Society. 2020; 2020: 1-26. Published 2020 Aug 25. doi: 10.1155/2020/1264175.

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Publication Date: 2020-08-25

Description: This paper studies the global stability of a discrete-time pathogen dynamic model with both cell-mediated and antibody immune responses. Both latently and actively infected cells are incorporated into the model. We discretize the continuous-time model by using the nonstandard finite difference (NSFD) method. We establish that NSFD preserves the nonnegativity and boundedness of the solutions of the model. We derive four threshold parameters which govern the existence and stability of the steady states. We establish by using the Lyapunov method, the global stability of the five steady states of the model. We illustrate our theoretical results by using numerical simulations.

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Existence of Solutions for the Discrete Dirichlet Problem Involving p-Mean Curvature Operator (2020)

Wang, Jianxia ; Zhou, Zhan

Hindawi

In: Discrete Dynamics in Nature and Society. 2020; 2020: 1-10. Published 2020 Aug 29. doi: 10.1155/2020/6591523.

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Publication Date: 2020-08-29

Description: This work is to discuss the Dirichlet boundary value problem of the difference equation with p -mean curvature operator. Under some determinate growth conditions on the nonlinear term, the existence of one solution or two nontrivial solutions is obtained via variational methods and some analysis techniques. Examples are also given to illustrate our theorems in the last section.

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Global Stability and Dynamic Analysis for a Type of Macroeconomic Systems (2020)

Yang, Ya-Juan ; Ma, Ru-Fei ; Zhang, Jing

Hindawi

In: Discrete Dynamics in Nature and Society. 2020; 2020: 1-10. Published 2020 Aug 28. doi: 10.1155/2020/4904829.

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Publication Date: 2020-08-28

Description: This paper aims at the dynamic properties of the proposed globally planned economic systems named after CPE proposed by Loo-Keng Hua who is one of the worldwide famous Chinese mathematicians. First, we give new existence conditions of growth balanced solution to the model. Second, we lead into the concept of stability for balanced output and carry out a theorem that deals with some equivalent conditions for judging a solution of output starting from the fact that any initial input can whether approach the existing balanced solution or not. Third, a new dynamic price system related to interest factors is proposed here and it is demonstrated that the new price equation is a much generalized one in comparison with the original price one which is only a special case of this new price equation. Also, relationships of the balanced solutions between the price and the output equation are investigated and the stability analysis is studied as well for the new price system. Finally, two examples are employed to illustrate the technical operation of input-output method and some new contributions of this article.

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Topics: Mathematics

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An Exponential Spline Difference Scheme for Solving a Class of Boundary Value Problems of Second-Order Ordinary Differential Equations (2020)

Cao, Dunqian

Hindawi

In: Discrete Dynamics in Nature and Society. 2020; 2020: 1-16. Published 2020 Aug 28. doi: 10.1155/2020/7056254.

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Publication Date: 2020-08-28

Description: In this paper, we mainly study an exponential spline function space, construct a basis with local supports, and present the relationship between the function value and the first and the second derivative at the nodes. Using these relations, we construct an exponential spline-based difference scheme for solving a class of boundary value problems of second-order ordinary differential equations (ODEs) and analyze the error and the convergence of this method. The results show that the algorithm is high accurate and conditionally convergent, and an accuracy of 1/240h6 was achieved with smooth functions.

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An Automatic System for Atrial Fibrillation by Using a CNN-LSTM Model (2020)

Ma, Fengying ; Zhang, Jingyao ; Chen, Wei ; [et al.]

Hindawi

In: Discrete Dynamics in Nature and Society. 2020; 2020: 1-9. Published 2020 Aug 28. doi: 10.1155/2020/3198783.

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Publication Date: 2020-08-28

Description: Atrial fibrillation (AF) is a common abnormal heart rhythm disease. Therefore, the development of an AF detection system is of great significance to detect critical illnesses. In this paper, we proposed an automatic recognition method named CNN-LSTM to automatically detect the AF heartbeats based on deep learning. The model combines convolutional neural networks (CNN) to extract local correlation features and uses long short-term memory networks (LSTM) to capture the front-to-back dependencies of electrocardiogram (ECG) sequence data. The CNN-LSTM is feeded by processed data to automatically detect AF signals. Our study uses the MIT-BIH Atrial Fibrillation Database to verify the validity of the model. We achieved a high classification accuracy for the heartbeat data of the test set, with an overall classification accuracy rate of 97.21%, sensitivity of 97.34%, and specificity of 97.08%. The experimental results show that our model can robustly detect the onset of AF through ECG signals and achieve stable classification performance, thereby providing a suitable candidate for the automatic classification of AF.

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Analysis of Dynamic Cournot Game in a Coopetition Supply Chain (2020)

Mai, Fengxia ; Zhang, Jianxiong ; Sun, Xiaojie

Hindawi

In: Discrete Dynamics in Nature and Society. 2020; 2020: 1-12. Published 2020 Jul 18. doi: 10.1155/2020/4168395.

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Publication Date: 2020-07-18

Description: In the original manufacturing industry, upstream encroachment has become a universal commercial phenomenon. This paper considers a coopetition supply chain consisting of an upstream original design manufacturer (ODM) and a downstream original equipment manufacturer (OEM) and proposes a dynamic Cournot game under bounded rationality. To cope with a dynamic repeated game in discrete time, a gradient adjustment mechanism is adopted. Furthermore, bifurcation diagram, largest Lyapunov exponent, basin of attraction, and critical curve are introduced to investigate the dynamic behavior of this game. The results obtained show that as the firms’ policy adjustment speeds increase, the stability region of the dynamic system gradually narrows, but one special finding is that the complex behavior of the dynamic system is alleviated as the OEM’s adjustment speed greatly increases. Moreover, when the difference between the two firms’ adjustment speeds is relatively small, the dynamic adjustment strategy is beneficial to the coopetition supply chain and both firms under certain adjustment speeds, as compared to a one-shot game. In addition, a higher product substitutability has a positive impact on the system stability, pushing the “cooperation” business alliance towards a more coordinated outcome.

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Research on Innovation Efficiency of Listed Companies in Development Zone Based on the Three-Stage DEA-Tobit Model: A Case Study of Hubei Province (2020)

Xu, Peng ; Luo, Fan ; Zhang, Ziyue ; [et al.]

Hindawi

In: Discrete Dynamics in Nature and Society. 2020; 2020: 1-12. Published 2020 Jul 18. doi: 10.1155/2020/1838469.

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Publication Date: 2020-07-18

Description: This study applies 3-stage data envelopment (DEA) of 24 listed companies in the development zone of Hubei Province from 2012 to 2017 based on the panel data; we used the DEA-Tobit model and regression analysis method on the sample in order to measure the factors affecting the innovation efficiency of listed companies and the efficiency of corporate innovation. The results demonstrated that the innovation efficiency of listed companies in the development zone of Hubei Province is relatively low. It is necessary to improve the innovation system of the development zone and give the full initiative to the role of corporate innovation as a mainstay. The four environmental variables of the number of enterprises, government subsidies, foreign direct investment in the development zone, and fixed asset investment have a significant impact on innovation efficiency. The enterprise size, operating capacity, and state-owned shares of the company have a significant positive impact on the innovation efficiency. But the number of years of the establishment has a significant negative impact on innovation efficiency. Moreover, the quality of the workers is not significant. Therefore, we must increase government investment in innovation to expand the scale of listed companies in the development zone, improve the environment for foreign investment, further strengthen the construction of talented people of companies, and enhance the original ability of innovation.

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On the Minimum Variable Connectivity Index of Unicyclic Graphs with a Given Order (2020)

Yousaf, Shamaila ; Bhatti, Akhlaq Ahmad ; Ali, Akbar

Hindawi

In: Discrete Dynamics in Nature and Society. 2020; 2020: 1-9. Published 2020 Jul 18. doi: 10.1155/2020/1217567.

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Publication Date: 2020-07-18

Description: The variable connectivity index, introduced by the chemist Milan Randić in the first quarter of 1990s, for a graph G is defined as ∑vw∈EGdv+γdw+γ−1/2, where γ is a non-negative real number and dw is the degree of a vertex w in G. We call this index as the variable Randić index and denote it by Rvγ. In this paper, we show that the graph created from the star graph of order n by adding an edge has the minimum Rvγ value among all unicyclic graphs of a fixed order n, for every n≥4 and γ≥0.

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