Zeyu Deng¹, Yuan Liang^1,*, Gengdong Cheng¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.30, No.4, pp. 1-1, 2024, DOI:10.32604/icces.2024.012504

Abstract Compared to single-material optimization, topology optimization of multi-material structures offers a larger design space. It also requires efficient material selection methods to provide guidance for designers. The predominant methods are based on interpolation schemes, which introduce order-dependence issues during the optimization process. This means the sequence in which materials are arranged can significantly impact the optimization outcomes and may lead to notable issues with material gradation. This paper identifies the mathematical essence of multi-material topology optimization as a nonlinear multi-valued integer programming problem. In this paper, we propose a novel stochastic discrete steepest descent multi-valued More >

Hanen Yaakoubi¹, Hegazy Rezk², Mujahed Al-Dhaifallah^3,4,*, Joseph Haggège¹

CMC-Computers, Materials & Continua, Vol.75, No.2, pp. 3657-3675, 2023, DOI:10.32604/cmc.2023.034929 - 31 March 2023

Abstract The present paper aims at validating a Model Predictive Control (MPC), based on the Mixed Logical Dynamical (MLD) model, for Hybrid Dynamic Systems (HDSs) that explicitly involve continuous dynamics and discrete events. The proposed benchmark system is a three-tank process, which is a typical case study of HDSs. The MLD-MPC controller is applied to the level control of the considered tank system. The study is initially focused on the MLD approach that allows consideration of the interacting continuous dynamics with discrete events and includes the operating constraints. This feature of MLD modeling is very advantageous… More >

Qingyuan Hu^1,*, Yuan Liang², Menghao Liu¹, Manfeng Hu¹, Yawen Mao¹

CMES-Computer Modeling in Engineering & Sciences, Vol.134, No.1, pp. 459-481, 2023, DOI:10.32604/cmes.2022.020327 - 24 August 2022

Abstract Topological optimization plays a guiding role in the conceptual design process. This paper conducts research on structural topology optimization algorithm within the framework of isogeometric analysis. For multi-component structures, the Nitsche’s method is used to glue different meshes to perform isogeometric multi-patch analysis. The discrete variable topology optimization algorithm based on integer programming is adopted in order to obtain clear boundaries for topology optimization. The sensitivity filtering method based on the Helmholtz equation is employed for averaging of curved elements' sensitivities. In addition, a simple averaging method along coupling interfaces is proposed in order to More >

Luyao Yang^1,#, Hao Chen^2,#, Haocheng Yu¹, Jin Qiu^1,*, Shuxian Zhu^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.134, No.1, pp. 731-745, 2023, DOI:10.32604/cmes.2022.020656 - 24 August 2022

Abstract Discrete Tomography (DT) is a technology that uses image projection to reconstruct images. Its reconstruction problem, especially the binary image (0–1 matrix) has attracted strong attention. In this study, a fixed point iterative method of integer programming based on intelligent optimization is proposed to optimize the reconstructed model. The solution process can be divided into two procedures. First, the DT problem is reformulated into a polyhedron judgment problem based on lattice basis reduction. Second, the fixed-point iterative method of Dang and Ye is used to judge whether an integer point exists in the polyhedron of More >

Chia-Nan Wang¹, Yu-Chen Wei², Po-Yuk So^3,*, Viet Tinh Nguyen⁴, Phan Nguyen Ky Phuc⁵

CMC-Computers, Materials & Continua, Vol.71, No.3, pp. 5875-5889, 2022, DOI:10.32604/cmc.2022.023880 - 14 January 2022

Abstract The garment industry in Vietnam is one of the country's strongest industries in the world. However, the production process still encounters problems regarding scheduling that does not equate to an optimal process. The paper introduces a production scheduling solution that resolves the potential delays and lateness that hinders the production process using integer programming and order allocation with a make-to-order manufacturing viewpoint. A number of constraints were considered in the model and is applied to a real case study of a factory in order to view how the tardiness and lateness would be affected which More >

Phan Nguyen Ky Phuc^*

Computer Systems Science and Engineering, Vol.40, No.1, pp. 75-85, 2022, DOI:10.32604/csse.2022.017793 - 26 August 2021

Abstract Stochastic demand is an important factor that heavily affects production planning. It influences activities such as purchasing, manufacturing, and selling, and quick adaption is required. In production planning, for reasons such as reducing costs and obtaining supplier discounts, many decisions must be made in the initial stage when demand has not been realized. The effects of non-optimal decisions will propagate to later stages, which can lead to losses due to overstocks or out-of-stocks. To find the optimal solutions for the initial and later stage regarding demand realization, this study proposes a stochastic two-stage linear programming… More >

Ali Abdi Seyedkolaei¹, Seyed Amin Hosseini Seno^1,*, Rahmat Budiarto²

CMC-Computers, Materials & Continua, Vol.68, No.3, pp. 3391-3410, 2021, DOI:10.32604/cmc.2021.017313 - 06 May 2021

Abstract In software-defined networking (SDN) networks, unlike traditional networks, the control plane is located separately in a device or program. One of the most critical problems in these networks is a controller placement problem, which has a significant impact on the network’s overall performance. This paper attempts to provide a solution to this problem aiming to reduce the operational cost of the network and improve their survivability and load balancing. The researchers have proposed a suitable framework called kernel search introducing integer programming formulations to address the controller placement problem. It demonstrates through careful computational studies More >

A. P. Chassiakos, C. I. Samaras, D. D. Theodorakopoulos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.4, pp. 9-18, 2000, DOI:10.3970/cmes.2000.001.461

Abstract Time and cost to complete a project is an important tradeoff problem in project planning and control. Existing methods have not provided an accepted solution in terms of both accuracy and efficiency. In an attempt to improve the solution process, a method is presented for developing optimal project time-cost curves based on CPM analysis. Using activity succession information, project paths are developed and duration is calculated. Following that, duration is reduced in an optimal way employing integer programming. Two alternative formulations are proposed which lead to corresponding algorithms, a progressive duration reduction and a direct More >