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  • 1. Bi, Zhuming
    et al.
    Wang, Lihui
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Wu, Chong
    Yang, Guilin
    Zhang, Dan
    Multidisciplinary Design Optimization in Engineering2013In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, p. 351097-Article in journal (Other academic)
  • 2. Chang, Q.
    et al.
    Gao, R.
    Lei, Y.
    Wang, Lihui
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Wu, C.
    Cyber-Physical Systems in Manufacturing and Service Systems2015In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, Vol. 2015, p. 1-2Article in journal (Refereed)
  • 3.
    Dalarsson, Mariana
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Emadi, Seyed Mohamad Hadi
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Norgren, Martin
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Perturbation Approach to Reconstructing Deformations in a Coaxial Cylindrical Waveguide2015In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, article id 915497Article in journal (Refereed)
    Abstract [en]

    We study a detection method for continuous mechanical deformations of coaxial cylindrical waveguide boundaries, using perturbation theory. The inner boundary of the waveguide is described as a continuous PEC structure with deformations modeled by suitable continuous functions. In the present approach, the computation complexity is significantly reduced compared to discrete conductor models studied in our previous work. If the mechanically deformed metallic structure is irradiated by the microwave fields of appropriate frequencies, then, by means of measurements of the scattered fields at both ends, we can reconstruct the continuous deformation function. We apply the first-order perturbation method to the inverse problem of reconstruction of boundary deformations, using the dominant TEM-mode of the microwave radiation. Different orders of Tikhonov regularization, using the L-curve criterion, are investigated. Using reflection data, we obtain reconstruction results that indicate an agreement between the reconstructed and true continuous deformations of waveguide boundaries.

  • 4. Ge, Qi
    et al.
    Jing, Xiao-Yuan
    Wu, Fei
    Yan, Jingjie
    Li, Hai-Bo
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Unsupervised Joint Image Denoising and Active Contour Segmentation in Multidimensional Feature Space2016In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, article id 3909645Article in journal (Refereed)
  • 5. Hu, Xing
    et al.
    Ma, Linhua
    Huang, Shaocheng
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Huang, Tianyu
    Liu, Shiping
    Dynamic Channel Slot Allocation Scheme and Performance Analysis of Cyclic Quorum Multichannel MAC Protocol2017In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, article id 8580913Article in journal (Refereed)
    Abstract [en]

    In high diversity node situation, multichannel MAC protocol can improve the frequency efficiency, owing to fewer collisions compared with single-channel MAC protocol. And the performance of cyclic quorum-based multichannel (CQM) MAC protocol is outstanding. Based on cyclic quorum system and channel slot allocation, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQMMAC protocol, a Markov chain model, which combines the channel-hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm. In addition, to improve the performance of CQM protocol in unsaturation situation, a dynamic channel slot allocation of CQM(DCQM) protocol is proposed, based on wavelet neural network. Finally, the performance of CQM protocol and DCQM protocol is simulated by Qualnet platform. And the simulation results show that the analytic and simulation results match very well; the DCQM performs better in unsaturation situation.

  • 6. Shao, Wen-Ze
    et al.
    Ge, Qi
    Gan, Zong-Liang
    Deng, Hai-Song
    Li, Haibo
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    A Generalized Robust Minimization Framework for Low-Rank Matrix Recovery2014In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, p. 656074-Article in journal (Refereed)
    Abstract [en]

    This paper considers the problem of recovering low-rank matrices which are heavily corrupted by outliers or large errors. To improve the robustness of existing recovery methods, the problem is solved by formulating it as a generalized nonsmooth nonconvex minimization functional via exploiting the Schatten p-norm (0 < p <= 1) and L-q(0 <q <= 1) seminorm. Two numerical algorithms are provided based on the augmented Lagrange multiplier (ALM) and accelerated proximal gradient (APG) methods as well as efficient root-finder strategies. Experimental results demonstrate that the proposed generalized approach is more inclusive and effective compared with state-of-the-art methods, either convex or nonconvex.

  • 7.
    Tan, Zhe
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Ersson, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Effect of TurboSwirl on Inclusions during Ingot Casting of Steels2015In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, article id 805734Article in journal (Refereed)
    Abstract [en]

    The use of TurboSwirl to obtain an improved steel cleanliness during filling of an ingot was numerically studied by VOF and DPM models. It was found that a radius-reduced TurboSwirl or a proper tapered mold entrance nozzle with an adequate developed region for steel flow can reduce the risk of mold flux entrapment in a mold. The ingot casting process can create highly turbulent conditions inside the mold during the initial stages of casting. Since the TurboSwirl generates much calmer filling conditions it can promote separation of large nonmetallic inclusions. The TurboSwirl also collects large inclusions (200 mu m) towards the axis of rotation, which should promote agglomeration. In addition, the residence time for inclusions of small sizes can be prolonged, increasing chance of agglomeration, which indirectly promotes their separation from steel. Moreover, the average turbulent dissipation rate in an ingot casting swirl setup is about 40 % higher than that in a no swirl setup. This further facilitates the agglomeration of inclusions before they enter the mold. The removal of nonmetallic inclusions is thus enhanced because of an increasing inclusion collision rate due to both Stokes collisions and turbulent collisions, while maintaining a calm flow inside the mold.

  • 8.
    Vynnycky, Michael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. KTH, School of Engineering Sciences (SCI), Mechanics.
    Reddy, G. M. M.
    Univ Sao Paulo Sao Carlos, Inst Math & Comp Sci, Dept Appl Math & Stat, POB 668, BR-13560970 Sao Carlos, SP, Brazil..
    On the Effect of Control-Point Spacing on the Multisolution Phenomenon in the P3P Problem2018In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, article id 5932508Article in journal (Refereed)
    Abstract [en]

    The perspective 3-point (P3P) problem, also known as pose estimation, has its origins in camera calibration and is of importance in many fields: for example, computer animation, automation, image analysis, and robotics. One possibility is to formulate it mathematically in terms of finding the solution to a quartic equation. However, there is yet no quantitative knowledge as to how control-point spacing affects the solution structure-in particular, the multisolution phenomenon. Here, we consider this problem through an algebraic analysis of the quartic's coefficients and its discriminant and find that there are significant variations in the likelihood of two or four solutions, depending on how the spacing is chosen. The analysis indicates that although it is never possible to remove the occurrence of the four-solution case completely, it could be possible to choose spacings that would maximize the occurrence of two real solutions. Moreover, control-point spacing is found to impact significantly on the reality conditions for the solution of the quartic equation.

  • 9. Wang, Rui
    et al.
    Liu, Guo-Ping
    Zhao, Yun-Bo
    Xia, Weiguo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Recent Advances on the Theory and Applications of Hybrid Systems2016In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, article id 6452926Article in journal (Other academic)
  • 10. Zhang, D.
    et al.
    Zhang, W. -A
    Wu, Z. -G
    Liu, Kun
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Zhang, H.
    Zhao, Y. -B
    New Advances in Distributed Control of Large-Scale Systems2015In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, Vol. 2015Article in journal (Refereed)
  • 11. Zhang, Yingfeng
    et al.
    Liu, Sichao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Sun, Shudong
    Clustering and Genetic Algorithm Based Hybrid Flowshop Scheduling with Multiple Operations2014In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147Article in journal (Refereed)
    Abstract [en]

    This research is motivated by a flowshop scheduling problem of our collaborative manufacturing company for aeronautic products. The heat-treatment stage (HTS) and precision forging stage (PFS) of the case are selected as a two-stage hybrid flowshop system. In HTS, there are four parallel machines and each machine can process a batch of jobs simultaneously. In PFS, there are two machines. Each machine can install any module of the four modules for processing the workpeices with different sizes. The problem is characterized by many constraints, such as batching operation, blocking environment, and setup time and working time limitations of modules, and so forth. In order to deal with the above special characteristics, the clustering and genetic algorithm is used to calculate the good solution for the two-stage hybrid flowshop problem. The clustering is used to group the jobs according to the processing ranges of the different modules of PFS. The genetic algorithm is used to schedule the optimal sequence of the grouped jobs for the HTS and PFS. Finally, a case study is used to demonstrate the efficiency and effectiveness of the designed genetic algorithm.

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