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  • 64101.
    Zhang, Hanzhu
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hedman, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Feng, Peizhong
    China University of Mining and Technology.
    Han, Gang
    University of Science and Technology Beijing.
    Akhtar, Farid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    A high entropy B4(HfMo2TaTi)C and SiC ceramic composite2019Conference paper (Refereed)
    Abstract [en]

    Refractory carbides HfC, Mo2C, TiC, TaC, B4C, and SiC were mixed with a molar ratio of 2:1:2:2:1:2 to fabricate multicomponent ceramic composite by pulsed current processing (PCP). From the starting materials that consist of face-centered cubic (FCC), hexagonal and rhombohedral crystal structures, the investigated carbide system is reported to form a single phase B4(HfMo2TaTi)C high-entropy ceramic (HEC) with SiC. The HEC phase contains uniform distribution of constitutional elements Hf, Mo, Ta, Ti, B and C, according to Energy dispersive X-ray spectroscopy (EDS) and wavelength dispersive X-ray spectroscopy (WDS) results.

    The fabricated HEC phase displays a hexagonal crystal structure, with a high average lattice distortion of 8.26% (Figure 1). The HCP structure was observed by X-ray diffraction and selected area diffraction in transmission electron microscopy (TEM). Density-functional theory (DFT) optimization suggested that the hexagonal crystal structure has alternating layers of metal atoms and carbon/boron atoms, i.e. metal atoms of Hf, Mo, Ta and Ti were distributed on the (0001) plane in the hexagonal lattice, while the carbon/boron atoms formed hexagonal 2D grids on the (0002) plane in the hexagonal unit cell. Despite of the vast differences in the crystal structures and lattice parameters among the utilized carbides, the formation of the unique hexagonal lattice structure of B4HfMo2TaTi)C can be a result of independent diffusion of the metal and nonmetal atoms. The sintered HEC ceramic composite exhibits excellent oxidation resistance at mediate temperature, 900 ºC for 50h, and elevated temperature, 2000 ºC for 20 s. Nanoindentation test shows that the HEC phase has a high hardness of 35 GPa. The remarkable improvement compared to the theoretical hardness value estimated based on the rule of mixtures (23 GPa) was contributed by the severe lattice distortion in the hexagonal structure.

  • 64102.
    Zhang, Hanzhu
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Luleå university of technology.
    Hedman, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Feng, Peizhong
    China University of Mining and Technology.
    Han, Gang
    University of Science and Technology Beijing.
    Akhtar, Farid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    A high-entropy B4(HfMo2TaTi)C and SiC ceramic composite2019In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 16, p. 5161-5167Article in journal (Refereed)
    Abstract [en]

    A multicomponent composite of refractory carbides, B4C, HfC, Mo2C, TaC, TiC and SiC, of rhombohedral, face-centered cubic (FCC) and hexagonal crystal structures is reported to form a single phase B4(HfMo2TaTi)C ceramic with SiC. The independent diffusion of the metal and nonmetal atoms led to a unique hexagonal lattice structure of the B4(HfMo2TaTi)C ceramic with alternating layers of metal atoms and C/B atoms. In addition, the classical differences in the crystal structures and lattice parameters among the utilized carbides were overcome. Electron microscopy, X-ray diffraction and calculations using density functional theory (DFT) confirmed the formation of a single phase B4(HfMo2TaTi)C ceramic with a hexagonal close-packed (HCP) crystal structure. The DFT based crystal structure prediction suggests that the metal atoms of Hf, Mo, Ta and Ti are distributed on the (0001) plane in the HCP lattice, while the carbon/boron atoms form hexagonal 2D grids on the (0002) plane in the HCP unit cell. The nanoindentation of the high-entropy phase showed hardness values of 35 GPa compared to the theoretical hardness value estimated based on the rule of mixtures (23 GPa). The higher hardness was contributed by the solid solution strengthening effect in the multicomponent hexagonal structure. The addition of SiC as the secondary phase in the sintered material tailored the microstructure of the composite and offered oxidation resistance to the high-entropy ceramic composite at high temperatures.

  • 64103.
    Zhang, Hanzhu
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Luleå university of technology.
    Hedman, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Feng, Peizhong
    China University of Mining and Technology.
    Han, Gang
    University of Science and Technology Beijing.
    Akhtar, Farid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Correction: A high-entropy B4(HfMo2TaTi)C and SiC ceramic composite2019In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 19, p. 6647-6647Article in journal (Refereed)
    Abstract [en]

    The authors regret that there is an error in writing the crystal structure in the article. The authors would like to address as follows:

    The presented XRD and TEM results revealed a hexagonal crystal structure. The following analyses including the identification of the lattice parameters and the DFT calculation were based on a hexagonal lattice. Therefore, the HCP (hexagonal close-packed) structure mentioned in the article should be regarded as a hexagonal structure. The HCP term used in the introduction, where the article from Joshua Gild et al. was cited, should also be regarded as hexagonal AlB2 structure.

    The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

  • 64104.
    Zhang, Heng
    et al.
    School of Information Engineering, East China Jiaotong University.
    Liu, Yanli
    School of Information Engineering, East China Jiaotong University.
    Xiong, Nealnaixue
    Department of Business and Computer Science, Southwestern Oklahoma State University.
    Imran, Muhammad Al
    College of Computer and Information Sciences, Almuzahmiyah, King Saud University.
    Vasilakos, Athanasios
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    An improved similarity based adaptive step size glowworm algorithm2015In: Journal of Internet Technology, ISSN 1607-9264, E-ISSN 2079-4029, Vol. 16, no 5, p. 905-914Article in journal (Refereed)
    Abstract [en]

    This paper presents the similarity based adaptive step size glowworm swarm optimization algorithm (SBASS-GSO), an improved version of glowworm swarm optimization algorithm (GSO). The standard GSO algorithm lacks unified metric standard to different problems in the selection of neighbor set, which makes the algorithm converge slowly because of improper selection. Because the step size s is fixed, the oscillation phenomenon may occur in local search space, which leads to inferior search accuracy In SBASS-GSO algorithm, we change neighborhood definition base on the similarity not on the distance. The neighborhood is selected by computing average similarity, which provides priori knowledge for the adaptive size s. The dynamic size s is useful for removing oscillation phenomenon and improving the convergence speed. Experimental results demonstrate the efficacy of the proposed glowworm algorithm in capturing multiple optima of a series of complex test functions, such as Zakharov and Sphere functions. We also provide some comparisons of SBASS-GSO with GSO and verify the superiority in the precision and convergence speed.

  • 64105.
    Zhang, Hui-ning
    et al.
    School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou.
    Li, Jian-li
    Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan.
    Xu, An-jun
    Metallurgical and Ecological Engineering School, University of Science and Technology, Beijing.
    Yang, Qixing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    He, Dong-feng
    Metallurgical and Ecological Engineering School, University of Science and Technology, Beijing.
    Tian, Nai-yuan
    Metallurgical and Ecological Engineering School, University of Science and Technology, Beijing.
    Carbothermic Reduction of Zinc and Iron Oxides in Electric Arc Furnace Dust2014In: Journal of Iron and Steel Research International, ISSN 1006-706X, E-ISSN 2210-3988, Vol. 21, no 4, p. 427-432Article in journal (Refereed)
    Abstract [en]

    The reduction of zinc and iron oxides from electric arc furnace dust (EAFD) by carbon was investigated at temperatures between 800 and 1300 °C. The analytic technique employed includes chemical analysis, X-ray fluorescence spectroscopy (XRF), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) equipped with X-ray energy dispersive spectrometry (EDS), and thermodynamic database FactSage 6. 2. It was found that the reduction of zinc and iron oxides depends largely on Boudouad reaction. At 900 °C, zinc exists in tested samples as ZnO, which is reduced in the temperature range of 1000 — 1100 °C. At 1100 °C, 99. 11% of the zinc is evaporated. The metallization ratio of Fe is 79. 19% at 1300 °C, as the content of Fe2+ is still 9. 40%. A higher temperature is thus required for a higher reduction degree of Fe oxides by solid or gaseous carbon

  • 64106.
    Zhang, J.
    et al.
    Northeastern University at Qinhuangdao.
    Tang, C.
    School of Civil and Hydraulic Engineering, Dalian University of Technology.
    Kou, S.
    Luleå tekniska universitet.
    Liang, Z.
    School of Civil and Hydraulic Engineering, Dalian University of Technology.
    Xu, T.
    School of Civil and Hydraulic Engineering, Dalian University of Technology.
    Mechanism of periodically distributed fracture in reinforced concrete beam under uniaxial tension2007In: Yingyong Lixue Xuebao, ISSN 1000-4939, Vol. 24, no 4, p. 646-651Article in journal (Refereed)
    Abstract [en]

    A numerical code RFPA3D(Three-Dimension Realistic Failure Process Analysis) is employeel to simulate the three-dimensional failure process of reinforced concrete under uniaxial tension. Then the analysis focuses on the stress distribution during the failure process and failure mechanism of the concrete and reinforcement. The numerical tests indicate the periodically distributed fracture in the reinforced concrete structure and the numerical analysis reproduces the complete process of the fracture initiation, infilling and saturation, 3D numerical tests with different thickness of concrete covers reveal that the eritical value of the fracture spacing increases and the crack numbers decreases with increasing ratio of the thickness of the concrete cover to that of the steel bar

  • 64107.
    Zhang, Jianyang
    et al.
    State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, People’s Republic of China.
    Dai, Dongxu
    State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, People’s Republic of China.
    Wang, Chia C.
    State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, People’s Republic of China.
    Harich, Steven A.
    State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, People’s Republic of China.
    Wang, Xiuyan
    State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, People’s Republic of China.
    Yang, Xueming
    State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, People’s Republic of China.
    Gustafsson, Magnus
    Department of Chemistry and Biochemistry, University of Colorado, Boulder.
    Skodje, Rex T.
    Department of Chemistry and Biochemistry, University of Colorado, Boulder.
    State to State to State Dynamics of the D+H2→HD+H Reaction: Control of Transition-State Pathways via Reagent Orientation2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 96, no 9, article id 93201Article in journal (Refereed)
    Abstract [en]

    The influence of reagent rotation on the dynamics of the D+H2→HD+H reaction is studied. The state-resolved differential cross section is measured using the Rydberg-atom scheme in a crossed beam experiment. It is found that the H2 rotation has a strong influence on the results. This effect was traced to the selection of the quantum bottleneck states through reagent orientation, thus suggesting a novel strategy to control the transition-state pathways in direct chemical reactions.

  • 64108.
    Zhang, Jie
    et al.
    State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China.
    Li, Wenli
    State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China.
    Shifa, Tofik Ahmed
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sun, Jiangbo
    State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China.
    Jia, Chuqiao
    State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China.
    Zhao, Yumin
    State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China.
    Cui, Yanbin
    State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China.
    Hierarchical porous carbon foam supported on carbon cloth as high-performance anodes for aqueous supercapacitors2019In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 439, article id 227066Article in journal (Refereed)
    Abstract [en]

    Carbon anodes have been widely utilized for the fabrication of high-performance asymmetric supercapacitors. However, they generally suffer from unsatisfactory energy density due to low specific capacitance arising from inferior conductivity and insufficient ionic diffusion rate. Here a surface modification method is conducted after the annealing of ZIF-67 precursor to produce hydrophilic, porous and heteroatom-doped carbon foam. On top of enhanced area capacitance, widened voltage window of −1.3–0 V (vs saturated calomel electrode) can be achieved through electrochemical reduction to suppress the hydrogen evolution reaction. The optimized reduced porous carbon foam on carbon cloth exhibits a maximum area capacitance of 1049 mF/cm2 at an applied current density of 12 mA/cm2 with excellent capacitance retention of 98.4% after 6000 charge-discharge cycles at 15 mA/cm2. By well pairing with hierarchical MnO2/CC cathode, a 2.3 V asymmetric supercapacitor in neutral aqueous Na2SO4 electrolyte is assembled, which delivers an exceptional energy density of up to 10.07 mWh/cm3. The procedure in this paper for carbonaceous material to simultaneously achieve considerable capacitance and enlarged voltage window can open up a wider prospect toward design of anodes for high-performance aqueous supercapacitor.

  • 64109.
    Zhang, Jixian
    et al.
    School of Information Science and Engineering, Yunnan University, Kunming, Yunnan 650504, PR China.
    Yang, Xutao
    School of Information Science and Engineering, Yunnan University, Kunming, Yunnan 650504, PR China.
    Xie, Ning
    School of Information Science and Engineering, Yunnan University, Kunming, Yunnan 650504, PR China.
    Zhang, Xuejie
    School of Information Science and Engineering, Yunnan University, Kunming, Yunnan 650504, PR China.
    Vasilakos, Athanasios V.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Li, Weidong
    School of Mathematics and Statistics, Yunnan University, Kunming, Yunnan 650504, PR China.
    An online auction mechanism for time-varying multidimensional resource allocation in clouds2020In: Future generations computer systems, ISSN 0167-739X, E-ISSN 1872-7115, Vol. 111, p. 27-38Article in journal (Refereed)
    Abstract [en]

    Multidimensional resource allocation is a hot topic in cloud computing, but current cloud platforms support only fixed resource allocation, that is, the user resource requirements are consistent throughout the usage period, which may cause a waste of resources and reduce the revenue of resource providers. Therefore, time-varying multidimensional resource allocation and the corresponding pricing mechanism represent a new challenge in cloud computing. We address the problem of online time-varying multidimensional resource allocation and pricing in clouds. Specifically, (1) we propose a novel integer programming model for the time-varying multidimensional resource allocation problem and (2) we design a truthful online auction mechanism for resource allocation in a competitive environment. For the resource allocation algorithm, we propose a waiting period strategy and dominant-resource-based strategy to improve the social welfare and resource utilization. Simultaneously, a payment pricing algorithm based on critical value theory is proposed. Finally, we prove that the mechanism is truthful and individual rationality. Compared with existing research, our approach is characterized by high social welfare, high resource utilization and short execution time.

  • 64110.
    Zhang, Juanrong
    et al.
    College of Civil Engineering, Zhengzhou University.
    Guo, Lijie
    Beijing General Research Institute of Mining and Metallurgy.
    Sun, Xiaoxiao
    College of Civil Engineering, Zhengzhou University.
    Li, Wenchen
    Beijing General Research Institute of Mining and Metallurgy.
    Jia, Qi
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Study on the Strength Development of Cemented Backfill Body from Lead-Zinc Mine Tailings with Sulphide2018In: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, Vol. 2018, article id 7278014Article in journal (Refereed)
    Abstract [en]

    The unconfined compressive strength (UCS) development of cemented backfill materials for lead-zinc mine tailings with sulphide was studied. The results showed that the UCS of the cemented backfill body with ordinary Portland cement (OPC) as binder decreased in the later curing days, regardless of particle size. Under the same conditions, the higher the OPC content, the higher the UCS of the cemented backfill body, and the UCS of the cemented backfill body began to decrease at the longer curing days. Under the same conditions, the finer the tailings, the lower the UCS of the cemented backfill body at each age, and the UCS of the cemented backfill body began to decrease at the earlier curing age. X-ray diffraction analysis (XRD) showed that the reduction of the UCS of the cemented backfill body was related to the formation of an expansive substance (expansive gypsum) in the cemented backfill body, which led to the cracking of the test sample. In the cemented backfill materials of coarse tailings of lead-zinc mine, the composite binder formed by OPC and calcined kaolin (CK) containing metakaolin was used; the amount of calcium hydroxide, the hydration product of cement, was reduced or eliminated due to the pozzolanic reaction of metakaolin; and the amount of expansive gypsum was reduced or eliminated, so the UCS of the cemented backfill body increased within 360 days of curing.

  • 64111.
    Zhang, L.an
    et al.
    Royal Institute of Technology (KTH), School of Industrial Engineering and Management, Department of Material Science and Engineering, Division of Energy and Furnace Technology.
    Nehme, Wassim
    Centre Énergétique et Procédés de Paris, Mines ParisTech.
    Biswas, Amit
    Royal Institute of Technology (KTH), School of Industrial Engineering and Management, Department of Material Science and Engineering, Division of Energy and Furnace Technology.
    Yang, Weihong
    Royal Institute of Technology (KTH), School of Industrial Engineering and Management, Department of Material Science and Engineering, Division of Energy and Furnace Technology.
    Blasiak, Włodzimierz
    Royal Institute of Technology (KTH), School of Industrial Engineering and Management, Department of Material Science and Engineering, Division of Energy and Furnace Technology.
    Bertin, D.
    EDF R and D, Avenue des Renardières-Ecuelles.
    Characterisation of heat transfer and flame length in a semi-scale industrial furnace equipped with HiTAC burner2010In: Journal of the Institute of Energy, ISSN 0144-2600, Vol. 83, no 3, p. 133-143Article in journal (Refereed)
    Abstract [en]

    This paper investigates the effects of multiple burner nozzles on the combustion characteristics, such as flame volume, heat transfer and NO x emission in a high temperature air combustion (HiTAC) industrial furnace. Experiments were carried out in one semi-industrial furnace located in Kungliga Tekniska Högskolan (Stockholm, Sweden). Three different types of burners were tested, including both regenerative and recuperative types. Variable flame temperature and oxygen concentration were applied in experiments. Heat transfer characteristics of HiTAC are studied in this paper, and the influences of a variety of inertial fuel/air jets are investigated for both flame length and NOx emission. One improved correlation between chemical flame length and flame Froude number is established for HiTAC with manifold nozzles. NOx emission is also correlated to the flame Froude number. The HiTAC recirculation system effects on flame shape, NOx emission and heat transfer were also examined. © 2010 Energy InstitutePublished by Maney on behalf of the Institute.

  • 64112.
    Zhang, Liangwei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    An Approach of Big Data Analytics for Fault Detection2014In: Newsletter of European Safety and Reliability Association, no December, p. 3-5Article in journal (Other (popular science, discussion, etc.))
    Download full text (pdf)
    fulltext
  • 64113.
    Zhang, Liangwei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Big Data Analytics for eMaintenance: Modeling of high-dimensional data streams2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Big Data analytics has attracted intense interest from both academia and industry recently for its attempt to extract information, knowledge and wisdom from Big Data. In industry, with the development of sensor technology and Information & Communication Technologies (ICT), reams of high-dimensional data streams are being collected and curated by enterprises to support their decision-making. Fault detection from these data is one of the important applications in eMaintenance solutions with the aim of supporting maintenance decision-making. Early discovery of system faults may ensure the reliability and safety of industrial systems and reduce the risk of unplanned breakdowns. Both high dimensionality and the properties of data streams impose stringent challenges on fault detection applications. From the data modeling point of view, high dimensionality may cause the notorious “curse of dimensionality” and lead to the accuracy deterioration of fault detection algorithms. On the other hand, fast-flowing data streams require fault detection algorithms to have low computing complexity and give real-time or near real-time responses upon the arrival of new samples. Most existing fault detection models work on relatively low-dimensional spaces. Theoretical studies on high-dimensional fault detection mainly focus on detecting anomalies on subspace projections of the original space. However, these models are either arbitrary in selecting subspaces or computationally intensive. In considering the requirements of fast-flowing data streams, several strategies have been proposed to adapt existing fault detection models to online mode for them to be applicable in stream data mining. Nevertheless, few studies have simultaneously tackled the challenges associated with high dimensionality and data streams. In this research, an Angle-based Subspace Anomaly Detection (ABSAD) approach to fault detection from high-dimensional data is developed. Both analytical study and numerical illustration demonstrated the efficacy of the proposed ABSAD approach. Based on the sliding window strategy, the approach is further extended to an online mode with the aim of detecting faults from high-dimensional data streams. Experiments on synthetic datasets proved that the online ABSAD algorithm can be adaptive to the time-varying behavior of the monitored system, and hence applicable to dynamic fault detection.

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    FULLTEXT01
  • 64114.
    Zhang, Liangwei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Big Data Analytics for Fault Detection and its Application in Maintenance2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Big Data analytics has attracted intense interest recently for its attempt to extract information, knowledge and wisdom from Big Data. In industry, with the development of sensor technology and Information & Communication Technologies (ICT), reams of high-dimensional, streaming, and nonlinear data are being collected and curated to support decision-making. The detection of faults in these data is an important application in eMaintenance solutions, as it can facilitate maintenance decision-making. Early discovery of system faults may ensure the reliability and safety of industrial systems and reduce the risk of unplanned breakdowns.

    Complexities in the data, including high dimensionality, fast-flowing data streams, and high nonlinearity, impose stringent challenges on fault detection applications. From the data modelling perspective, high dimensionality may cause the notorious “curse of dimensionality” and lead to deterioration in the accuracy of fault detection algorithms. Fast-flowing data streams require algorithms to give real-time or near real-time responses upon the arrival of new samples. High nonlinearity requires fault detection approaches to have sufficiently expressive power and to avoid overfitting or underfitting problems.

    Most existing fault detection approaches work in relatively low-dimensional spaces. Theoretical studies on high-dimensional fault detection mainly focus on detecting anomalies on subspace projections. However, these models are either arbitrary in selecting subspaces or computationally intensive. To meet the requirements of fast-flowing data streams, several strategies have been proposed to adapt existing models to an online mode to make them applicable in stream data mining. But few studies have simultaneously tackled the challenges associated with high dimensionality and data streams. Existing nonlinear fault detection approaches cannot provide satisfactory performance in terms of smoothness, effectiveness, robustness and interpretability. New approaches are needed to address this issue.

    This research develops an Angle-based Subspace Anomaly Detection (ABSAD) approach to fault detection in high-dimensional data. The efficacy of the approach is demonstrated in analytical studies and numerical illustrations. Based on the sliding window strategy, the approach is extended to an online mode to detect faults in high-dimensional data streams. Experiments on synthetic datasets show the online extension can adapt to the time-varying behaviour of the monitored system and, hence, is applicable to dynamic fault detection. To deal with highly nonlinear data, the research proposes an Adaptive Kernel Density-based (Adaptive-KD) anomaly detection approach. Numerical illustrations show the approach’s superiority in terms of smoothness, effectiveness and robustness.

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    knbe
  • 64115.
    Zhang, Liangwei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Dynamic fault detection from high-dimensional data streams2015In: Newsletter of European Safety and Reliability Association, no June, p. 2-4Article in journal (Other (popular science, discussion, etc.))
    Download full text (pdf)
    FULLTEXT01
  • 64116.
    Zhang, Liangwei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Karim, Ramin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Big Data Mining in eMaintenance: An Overview2014In: Proceedings of the 3rd international workshop and congress on eMaintenance: June 17-18 Luleå, Sweden : eMaintenance, Trends in technologies & methodologies, challenges, possibilites and applications / [ed] Uday Kumar; Ramin Karim; Aditya Parida; Philip Tretten, Luleå: Luleå tekniska universitet, 2014, p. 159-170Conference paper (Refereed)
    Abstract [en]

    Maintenance related data are tending to be increasingly huge involume, rapid in velocity and vast in variety. Data with thesecharacteristics bring new challenges with respect to data analysisand data mining, which requires new approaches andtechnologies. In industry, related research and applications, somecontributions have been provided to utilize Big Data technologiesfor extraction of information through pattern recognitionmechanisms via eMaintenance solutions. Today, the existingcontributions are not enabling a holistic approach for maintenancedata analysis and therefore are insufficient. However, theimmense value hidden inside the Big Data in eMaintenance isarousing more and more attention from both academia andindustry. Hence, this paper aims to explore eMaintenancesolutions for maintenance decision-making through utilization ofBig Data technologies and approaches. The paper discusses BigData mining in eMaintenance through a general manner byemploying one of the widely accepted frameworks with the nameof Cross Industry Standard Process for Data Mining (CRISPDM).In addition, the paper outlines features of maintenance dataand investigates six sub-processes (i.e. business understanding,data understanding, data preparation, modeling, evaluation anddeployment) of data mining applications defined by CRISP-DMwithin the domain of eMaintenance.

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    FULLTEXT01
  • 64117.
    Zhang, Liangwei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lin, Janet
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Karim, Ramin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Adaptive Kernel Density-based Anomaly Detection for Nonlinear Systems2018In: Knowledge-Based Systems, ISSN 0950-7051, E-ISSN 1872-7409, Vol. 139, no 1, p. 50-63Article in journal (Refereed)
    Abstract [en]

    This paper presents an unsupervised, density-based approach to anomaly detection. The purpose is to define a smooth yet effective measure of outlierness that can be used to detect anomalies in nonlinear systems. The approach assigns each sample a local outlier score indicating how much one sample deviates from others in its locality. Specifically, the local outlier score is defined as a relative measure of local density between a sample and a set of its neighboring samples. To achieve smoothness in the measure, we adopt the Gaussian kernel function. Further, to enhance its discriminating power, we use adaptive kernel width: in high-density regions, we apply wide kernel widths to smooth out the discrepancy between normal samples; in low-density regions, we use narrow kernel widths to intensify the abnormality of potentially anomalous samples. The approach is extended to an online mode with the purpose of detecting anomalies in stationary data streams. To validate the proposed approach, we compare it with several alternatives using synthetic datasets; the approach is found superior in terms of smoothness, effectiveness and robustness. A further experiment on a real-world dataset demonstrated the applicability of the proposed approach in fault detection tasks.

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  • 64118.
    Zhang, Liangwei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lin, Janet
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Karim, Ramin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    An Angle-based Subspace Anomaly Detection Approach to High-dimensional Data: With an Application to Industrial Fault Detection2015In: Reliability Engineering & System Safety, ISSN 0951-8320, E-ISSN 1879-0836, Vol. 142, p. 482-497Article in journal (Refereed)
    Abstract [en]

    The accuracy of traditional anomaly detection techniques implemented on full-dimensional spaces degrades significantly as dimensionality increases, thereby hampering many real-world applications. This work proposes an approach to selecting meaningful feature subspace and conducting anomaly detection in the corresponding subspace projection. The aim is to maintain the detection accuracy in high-dimensional circumstances. The suggested approach assesses the angle between all pairs of two lines for one specific anomaly candidate: the first line is connected by the relevant data point and the center of its adjacent points; the other line is one of the axis-parallel lines. Those dimensions which have a relatively small angle with the first line are then chosen to constitute the axis-parallel subspace for the candidate. Next, a normalized Mahalanobis distance is introduced to measure the local outlier-ness of an object in the subspace projection. To comprehensively compare the proposed algorithm with several existing anomaly detection techniques, we constructed artificial datasets with various high-dimensional settings and found the algorithm displayed superior accuracy. A further experiment on an industrial dataset demonstrated the applicability of the proposed algorithm in fault detection tasks and highlighted another of its merits, namely, to provide preliminary interpretation of abnormality through feature ordering in relevant subspaces.

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  • 64119.
    Zhang, Liangwei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lin, Janet
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Karim, Ramin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Sliding Window-based Fault Detection from High-dimensional Data Streams2017In: IEEE Transactions on Systems, Man & Cybernetics. Systems, ISSN 2168-2216, Vol. 47, no 2, p. 289-303, article id 7509594Article in journal (Refereed)
    Abstract [en]

    High-dimensional data streams are becoming increasingly ubiquitous in industrial systems. Efficient detection of system faults from these data can ensure the reliability and safety of the system. The difficulties brought about by high dimensionality and data streams are mainly the ``curse of dimensionality'' and concept drifting, and one current challenge is to simultaneously address them. To this purpose, this paper presents an approach to fault detection from nonstationary high-dimensional data streams. An angle-based subspace anomaly detection approach is proposed to detect low-dimensional subspace faults from high-dimensional datasets. Specifically, it selects fault-relevant subspaces by evaluating vectorial angles and computes the local outlier-ness of an object in its subspace projection. Based on the sliding window strategy, the approach is further extended to an online mode that can continuously monitor system states. To validate the proposed algorithm, we compared it with the local outlier factor-based approaches on artificial datasets and found the algorithm displayed superior accuracy. The results of the experiment demonstrated the efficacy of the proposed algorithm. They also indicated that the algorithm has the ability to discriminate low-dimensional subspace faults from normal samples in high-dimensional spaces and can be adaptive to the time-varying behavior of the monitored system. The online subspace learning algorithm for fault detection would be the main contribution of this paper.

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  • 64120. Zhang, Liangwei
    et al.
    Lin, Jing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Liu, Bin
    An Overview of Deep Learning in Prognostics and Health Management2019In: 2019 Reliability & Maintainability Symposium (RAMS) January 28-31, 2019 , Orlando, FL, USA: RAMS® 2019, 2019Conference paper (Refereed)
  • 64121.
    Zhang, Liangwei
    et al.
    Department of Industrial Engineering, Dongguan University of Technology, Dongguan, China.
    Lin, Jing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Liu, Bin
    Department of Management Science, University of Strathclyde, Glasgow, U.K..
    Zhang, Zhicong
    Department of Industrial Engineering, Dongguan University of Technology, Dongguan, China.
    Yan, Xiaohui
    Department of Industrial Engineering, Dongguan University of Technology, Dongguan, China.
    Wei, Muheng
    Oceanic Intelligent Technology Innovation Center, CSSC Systems Engineering Research Institute, Beijing, China.
    A Review on Deep Learning Applications in Prognostics and Health Management2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 162415-162438Article, review/survey (Refereed)
    Abstract [en]

    Deep learning has attracted intense interest in Prognostics and Health Management (PHM), because of its enormous representing power, automated feature learning capability and best-in-class performance in solving complex problems. This paper surveys recent advancements in PHM methodologies using deep learning with the aim of identifying research gaps and suggesting further improvements. After a brief introduction to several deep learning models, we review and analyze applications of fault detection, diagnosis and prognosis using deep learning. The survey validates the universal applicability of deep learning to various types of input in PHM, including vibration, imagery, time-series and structured data. It also reveals that deep learning provides a one-fits-all framework for the primary PHM subfields: fault detection uses either reconstruction error or stacks a binary classifier on top of the network to detect anomalies; fault diagnosis typically adds a soft-max layer to perform multi-class classification; prognosis adds a continuous regression layer to predict remaining useful life. The general framework suggests the possibility of transfer learning across PHM applications. The survey reveals some common properties and identifies the research gaps in each PHM subfield. It concludes by summarizing some major challenges and potential opportunities in the domain.

  • 64122.
    Zhang, Ping
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    A 3DEC numerical analysis of the interaction between uneven rock surface and shotcrete lining: Validation of physical model and evaluation of influence of unevenness on the support effect of shotcrete2013Report (Other academic)
    Abstract [en]

    Although shotcrete (sprayed concrete) has been widely used as rock support in mines and in civil engineering projects, the complex interaction between shotcrete and rock has not been studied well. The main reason is that the performance of shotcrete is influenced by a number of important parameters.Experiences from previous research and past projects show that the unevenness of rock surface has a large impact on the number of failures at the interface and in the lining. Furthermore, the behaviour of the lining is sensitive to small amplitudes of the surface roughness. Although people have done some experimental and numerical analysis, the influence of the complex unevenness of three dimensional shaped surfaces on the shotcrete – rock interaction has not been well studied.The project here focuses on the influence of the surface unevenness of a circular opening on the support effect of shotcrete. The work was done by using a 3D numerical simulation (3DEC) and was conducted in two stages. In stage 1, the numerical model was validated by comparing with physical model tests by Chang (1994). In stage 2, based on the well validated numerical model, the influence of unevenness on the support effect of shotcrete was further investigated.

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  • 64123.
    Zhang, Ping
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Dineva, Savka
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Hansen-Haug, Jouni
    Lundin Mining.
    Woldemedhin, Biruk
    LKAB.
    Töyrä, Jimmy
    LKAB.
    Boskovic, Mirjana
    LKAB.
    Nyström, Anders
    Boliden.
    Marklund, Per-Ivar
    Boliden.
    Mozaffari, Shahram
    Boliden.
    Establishment of experimental sites in three Swedish mines to monitor the in-situ performance of ground support systems associated with mining-induced seismicity2016In: Proceedings of the 8th International Symposium on Ground Support in Mining and Underground Construction / [ed] E . N ordlund, T.H. Jones and A. Eitzenberger (eds), 2016Conference paper (Refereed)
    Abstract [en]

    In order to assess the performance of ground support components and systems when subjected to seismic activity and strong ground motion, Luleå University of Technology together with three Swedish mining companies (Lundin Mining, LKAB and Boliden) started a three year research project in September 2014. The aim of the project is to develop new methods for evaluating the rock support performance in-situ that use all available information about i) the source of the seismic event (obtained from the seismic network in the mine and additional seismic sensors), ii) seismic loading (ground motion) recorded by temporary local seismic networks, and iii) the consequences of the seismic loading in terms of damage to the underground excavations and the rock support.The sites with high potential of seismic damage were defined after the historical damaging seismic events were reviewed and the mining-induced stress disturbance was investigated with 3D numerical models. As of 31 December 2015, four sites in three different mines have been instrumented. Geophones (in depth and at surface), multi-points extensometers and instrumented bolts were installed to monitor the ground motion, the deformation of the rock mass and the elongation of the bolts. Observation boreholes were drilled to investigate the rock lithology, structures as well as fracture distribution and development. The data from locally installed geophones will be integrated with seismic data recorded by the mine-wide network. For each monitoring point, all of the instruments and observation boreholes were located at very close area within 0.5-1 m distance from each other. These results will be used to establish the relationship between the dynamic loading and the response of rock mass and rock bolts. Additionally, laser scanning is used to measure the surface deformation of the whole volume of instrumented sites with time. Two damaging seismic events occurred near the instrumented sites after the instruments were installed and the results of site investigation show that installed instruments have captured the response of the rock mass and bolts due to production blasting and seismic events.

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  • 64124. Zhang, Ping
    et al.
    Li, Ning
    Xi'an University of Technology.
    Li, Xibing
    School of Resources and Safety Engineering, Central South University, Changsha.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Compressive failure model for brittle rocks by shear faulting and its evolution of strength components2009In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 46, no 5, p. 830-841Article in journal (Refereed)
    Abstract [en]

    A physical theory for brittle failure is presented that aims to explain both the phenomenological and micro-structural observations. The objective of this model is to capture the important attributes inferred from micro-structural experiments so as to arrive at constitutive relations that describe macroscopic failure behaviour. Based on experimental results, the micromechanical failure character- isation is summarised first. The localised failure process of rock will experience two stages: the brittle breakage stage (bond rupture of rock bridge) and the sliding stage (frictional resistance of failure plane mobilisation). A physical model is developed by dividing the sample into elastic and localised shear zones. Furthermore, the deformation process of the localised shear zone is divided into bond loss and frictional resistance mobilisation in two stages. To combine the micro-characteristics with the macromechanical properties, the chain models in localised shear zone, and the homogenisation method are adopted. The model is validated against the experimental data of Yumlu and Ozbay's. Subsequently, the localised progressive failure characteristics of rock are analysed by changing the model's parameters. The intrinsic effects and influential factors such as geometrical effects (size effect, shape effect), the strain softening phenomenon and Class II stress-strain curves are revealed. Finally, in order to be used easily by engineers, the simplified description of rock failure process and its evolution of strength components are given based on the model.

  • 64125.
    Zhang, Ping
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mikromechanical modeling of fire-induced thermal damae in a laboratory model tunnel2015Conference paper (Other academic)
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  • 64126.
    Zhang, Ping
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mainali, Ganesh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Saiang, Christine
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Jansson, Robert
    SP Sveriges Tekniska Forskningsinstitut.
    Experimental study of thermal spalling on rock blocks exposed to different fire/heating conditions2011In: Bergmekanikdag 2011: Föredrag, Stiftelsen bergteknisk forskning - Befo , 2011, p. 53-63Conference paper (Other academic)
  • 64127.
    Zhang, Ping
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mainali, Ganesh
    Saiang, Christine
    Jansson, Robert
    SP Technical Research Institute of Sweden.
    Adl-Zarrabi, Bijan
    SP Technical Research Institute of Sweden.
    Experimental study on thermal spalling of rock blocks exposed to fire2010In: Bergmekanikk i Norden 2010 = Rock mechanics in the Nordic countries 2010 / [ed] Charlie C. Li, Kongsberg, Norway, 9.-12. June 2010, 2010, p. 294-305Conference paper (Refereed)
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  • 64128.
    Zhang, Ping
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Swan, Graham
    Rock Mechanics and Mine Design, Sudbury, Canada.
    Yi, Changping
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Velocity Amplification of Seismic Waves Through Parallel Fractures Near a Free Surface in Fractured Rock: A Theoretical Study2019In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 52, no 1, p. 199-213Article in journal (Refereed)
    Abstract [en]

    To determine the dynamic demand for support design under rockburst conditions, one of the most important issues is the prediction of ground motion parameters at the site of interest. Field monitoring has shown that the peak ground motion at the surface of an excavation in fractured rock is preferentially amplified compared to the motion in solid rock at a similar distance from the source. However, the traditional scaling laws used in rock support design do not account for the effect of free surface (excavation) and fracturing of rock. Recent studies have shown that high ground motion might be generated when a seismic wave crosses through fractures near a free surface in fractured rocks which is very complex and is not well understood. In this paper, particle velocity amplification was theoretically studied by investigating the dynamic interaction between seismic wave and multiple fractures near a free surface using the method of characteristics and the displacement discontinuity model. A harmonic load was applied on a model with a fractured zone near a free surface to investigate this phenomenon. After the harmonic wave propagated normally through multiple parallel fractures, the velocity amplification factor (VAF) was calculated as a function of the ratio of the magnitude of the peak particle velocity at the free surface of the model to the peak input velocity. The VAF can be as high as 3.77 and varies depending on the state of the fractured rock and the characteristics of the seismic wave. Parameter studies were conducted to investigate the effects of seismic load and multiple fractures on wave propagation, especially in terms of the wave frequency, the fracture spacing, the number of fractures and the stiffness of fractures. The results have proved that the interaction of the seismic wave and multiple fractures near the free surface strongly influences the ground motion. Quantitative relationships between the various influential factors and the corresponding VAF were developed. It is anticipated that such relationships can provide criteria to improve the current design procedures and help mining engineers to improve their rock support practice for rockburst-prone areas.

  • 64129.
    Zhang, Ping
    et al.
    Department of Geophysics, Uppsala University.
    Rasmussen, Thorkild Maack
    Department of Geophysics, Uppsala University.
    Pedersen, Laust Börsting
    Department of Geophysics, Uppsala University.
    Electric resistivity structure of the Siljan impact region ( Sweden)1988In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 93, no B6, p. 6485-6501Article in journal (Refereed)
    Abstract [en]

    Based on 65 magnetotelluric (MT) measuring stations, a cross section of the electric conductivity structure in the Siljan impact area, located in the central part of Sweden, is presented. Static shift effects due to local near-surface inhomogeneities are present in nearly all of the MT soundings.In an attempt to correct for near-surface distortions, average impedance data and distortion parameters were interpreted. Derived 2-D models show some coincidence with seismic reflection results and support an impact origin of the Siljan area. Fluid migration through the fractures generated by the impact is one possible explanation for the anomalously high conductivity within the upper crust

  • 64130.
    Zhang, Ping
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Swan, Graham
    Rock Mechanics and Mine Design, Canada.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    1D numerical simulation of velocity amplification of P-waves travelling through fractured rock near a free surface2015In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 115, no 11, p. 1121-1126Article in journal (Refereed)
    Abstract [en]

    The most widely used support design damage criterion for rockburst-prone mines is based upon kinetic energy, which is proportional to the square of the ejection velocity and is commonly expressed in terms of peak particle velocity (PPV). Field monitoring and back-analyses have shown that ejection velocities of the order of 10 m/s and higher can result from seismic events of moderate magnitude. Such velocities are much higher than those predicted using PPV obtained from scaling laws. It has also been found that the peak ground motion (i.e. PPV) on the surface of an excavation is preferentially amplified (by four-to tenfold) compared to the motion in solid rock at a similar distance from the source. However, the wave propagation and interaction processes involved within the fractured rock in generating high ground motion are very complex and are not well understood at this time. In this paper, velocity amplification was investigated by modelling the dynamic interaction between fractured rock and a free surface using a 2D discontinuum-based numerical program, UDEC (Universal Distinct Element Code). A 1D model with a fractured zone was used to represent the fractured rock. Velocity amplification, quantified by PPV, predicted at the free end of the model was 2.0-3.6 times higher than the input velocity. It was found that the wave frequency, fracture stiffness, fracture spacing, and thickness of fractured zone are the main factors that affect the velocity amplification. The results have proved that the interaction of the seismic wave and multiple fractures near the free surface strongly influences the ground motion

  • 64131.
    Zhang, Ping
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Yi, Changping
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Shirzadegan, Shahin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nyberg, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Malmgren, Lars
    Mining Technology R and D, LKAB Kiruna Mine.
    Nordqvist, Anders
    LKAB.
    Numerical back-analysis of simulated rockburst field tests by using coupled numerical technique2013In: Ground Support 2013: Proceedings of the Seventh International Symposium on Ground Support in Mining and Underground Construction / [ed] Yves Potvin; B.G.H. Brady, Perth, Australia: Australian Center for Geomechanics , 2013, p. 565-581Conference paper (Refereed)
    Abstract [en]

    In order to assess the capacity of ground support systems when submitted to dynamic loading, simulated rockburst tests utilizing blasting have been performed for many years in different countries with limited success. In general, the blasts need to be carefully designed in order to reach the goal; however, different blast layouts (e.g. blasthole angle, burden) have been used based on researcher’s experience without conducting detailed analyses, the exception being a field test by CSIR. Recently, field trials have been conducted at the LKAB Kiirunavaara underground mine with some unexpected results which show that either the whole tested panel was destroyed or only a few fractures were formed without any ejections being observed. The aim of this paper is to investigate the failure mechanism in the simulated rockburst tests and improve the blast design by back-analyzing the test results using a coupled numerical modeling technique. The blast was simulated by using finite element method (LS-DYNA) and the dynamic interaction between the blasting generated waves and the opening was simulated by using discrete element modeling (UDEC) with the dynamic input from LS-DYNA. The numerical modeling showed that blasting can create both radial fractures radiating from the blasthole and fractures parallel or sub-parallel to the surface of the tested panel caused by reflected tensile stress waves. By comparing the results of the numerical modeling with the measured data, it is shown that the collapse failure was mainly controlled by the creation of a cone-shaped area formed by radial fractures and the burden seems to be a critical factor. In order to obtain fractures caused by reflected tensile stress waves and reduce blasting induced radial fractures, 2 parallel blastholes are suggested with larger burden (> 5 m) for future tests. Furthermore, the limitation of the current numerical modeling has also been discussed. The coupled numerical technique has shown its advantage when simulating blasting as well as interaction between waves and opening and it can thus be used as a tool for extrapolating results from simulated rockburst experiments if detailed geological structure and ground support system can be incorporated in the model and the model can be well calibrated.

  • 64132. Zhang, Ping
    et al.
    Yin, J.J.
    Hunan University.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Li, N.
    Xi'an University of Technology.
    Determination and verification of the longitudinal deformation profile in a horse-shoe shaped tunnel using two-stage excavation2008In: MassMin 2008: Proceedings of the 5th International Conference and Exhibition on Mass Mining, Lulea, Sweden 9-11 June 2008 / [ed] Håkan Schunnesson; Erling Nordlund, Luleå: Luleå tekniska universitet, 2008, p. 845-854Conference paper (Refereed)
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  • 64133.
    Zhang, Qingke
    et al.
    School of Computer Science and technology, Engineering Research Center of Digital Media Technology, Ministry of Education, Shandong University, Jinan.
    Liu, Weiguo
    School of Computer Science and technology, Engineering Research Center of Digital Media Technology, Ministry of Education, Shandong University, Jinan.
    Men, Xiangxu
    School of Computer Science and technology, Engineering Research Center of Digital Media Technology, Ministry of Education, Shandong University, Jinan.
    Jiang, Bo
    Shandong Provincial Key Laboratory of Network based Intelligent Computing, University of Jinan.
    Vasilakos, Athanasios
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vector coevolving particle swarm optimization algorithm2017In: Information Sciences, ISSN 0020-0255, E-ISSN 1872-6291, Vol. 394-395, p. 273-298Article in journal (Refereed)
    Abstract [en]

    In this paper, we propose a novel vector coevolving particle swarm optimization algorithm (VCPSO). In VCPSO, the full dimension of each particle is first randomly partitioned into several sub-dimensions. Then, we randomly assign either one of our newly designed scalar operators or learning operators to update the values in each sub-dimension. The scalar operators are designed to enhance the population diversity and avoid premature convergence. In addition, the learning operators are designed to enhance the global and local search ability. The proposed algorithm is compared with several other classical swarm optimizers on thirty-three benchmark functions. Comprehensive experimental results show that VCPSO displays a better or comparable performance compared to the other algorithms in terms of solution accuracy and statistical results.

  • 64134.
    Zhang, Qinglin
    et al.
    Royal Institute of Technology (KTH), School of Industrial Engineering and Management, Department of Material Science and Engineering, Division of Energy and Furnace Technology.
    Dor, Liran
    Environmental Energy Resources Ltd..
    Biswas, Amit
    Royal Institute of Technology (KTH), School of Industrial Engineering and Management, Department of Material Science and Engineering, Division of Energy and Furnace Technology.
    Yang, Weihong
    Royal Institute of Technology (KTH), School of Industrial Engineering and Management, Department of Material Science and Engineering, Division of Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    Royal Institute of Technology (KTH), School of Industrial Engineering and Management, Department of Material Science and Engineering, Division of Energy and Furnace Technology.
    Modeling of steam plasma gasification for municipal solid waste2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 106, p. 546-554Article in journal (Refereed)
    Abstract [en]

    Plasma gasification melting (PGM) is a promising gasification technology aiming at providing sustainable disposal for various wastes. In this work, an Euler-Euler multiphase model was developed to study the characteristics of air and steam gasification of municipal solid waste in a PGM reactor. The model is validated by measurement data from a demonstration PGM reactor. With this model, three groups of simulations were performed to study the influences of operating conditions. It is confirmed that injection of high temperature steam is important for increasing the cold gas efficiency and syngas lower-heating-value. The effect of steam injection is affected by steam feeding rate, air feeding rate and plasma power. Based on the simulated results, an optimal condition is suggested for air and steam gasification in the PGM reactor. © 2012 Elsevier B.V.

  • 64135.
    Zhang, Qinhong
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Dong, Ming
    School of Management, Shanghai Jiao Tong University.
    Lou, Jianwen
    School of Management, Shanghai Jiao Tong University.
    Segerstedt, Anders
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Supply Chain Coordination with Trade Credit and Quantity Discount Incorporating Default Risk2014In: International Journal of Production Economics, ISSN 0925-5273, E-ISSN 1873-7579, Vol. 153, p. 352-360Article in journal (Refereed)
    Abstract [en]

    We explore the issue of supply chain coordination by considering trade credit and its risk. It shows that, in a retailer-manufacturer system, the manufacturer may deliver less than the retailer's order quantity when the payment is delayed, and the manufacturer's risk aversion makes this result hold in a wider range. These findings are different from the common sense believed in the retailer-manufacturer coordination literature, which suggests the manufacturer to entice the retailer to enlarge the lot size. The manufacturer's decision of decreasing the order quantity prevents the supply chain from operating in the optimal situation. In order to coordinate supply chain, we propose a modified quantity discount based on both order quantity and advance payment which means the manufacturer offers quantity discount if the retailer pays part of the payment in advance and enlarges her order quantity. The ranges of advance payment ratio and the quantity discount are derived. Numerical examples are used to demonstrate the conclusions.

  • 64136.
    Zhang, Qinhong
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Segerstedt, Anders
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Tsao, Yun-Chung
    Department of Industrial Management, National Taiwan University of Science and Technology, Taipei.
    Liu, Biyu
    School of Economics and Management, Fuzhou University.
    Returnable packaging management in automotive parts logistics: dedicated mode and shared mode2015In: International Journal of Production Economics, ISSN 0925-5273, E-ISSN 1873-7579, Vol. 168, p. 234-244Article in journal (Refereed)
    Abstract [en]

    We compare two different modes, i.e., dedicated mode and shared mode, used in packaging management in automotive parts logistics. In dedicated mode, every parts supplier uses his own packaging; while in shared mode, packages can be shared among the suppliers. For each mode, we calculate the total costs consisting of transportation cost and inventory holding cost, and prove that the total costs, the transportation cost and the inventory holding cost are all smaller under shared mode. We further illustrate the factors that influence the cost savings of shared mode, i.e., the total cost of dedicated mode minus that of shared mode. In particular, the cost savings are proved to be negatively related to the number of package categories, and are positively related to: (1) the demand gap of packages between areas, i.e., sum of the volume difference of every kind of packages that transported in and out of one area; (2) the failed ratio factor of the returned packages, i.e., the ratio of the packages that cannot be returned to the supplier because of broken, pilferage, misplace, etc.; and (3) the time savings of short distance transportation, i.e., the transportation time consumed between areas minus the transportation time within one area. Finally, numerical examples show that the cost savings can be considerable, and the number of package categories is the most important influence factor.

  • 64137.
    Zhang, Qinhong
    et al.
    Sino-US Global Logistics Institute, Shanghai Jiao Tong University.
    Zhang, Dali
    Sino-US Global Logistics Institute, Shanghai Jiao Tong University.
    Segerstedt, Anders
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Luo, Jianwen
    School of Management, Shanghai Jiao Tong University.
    Optimal ordering and pricing decisions for a company issuing product-specific gift cards2018In: Omega: The International Journal of Management Science, ISSN 0305-0483, E-ISSN 1873-5274, Vol. 74, p. 92-102Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate gift card's influence on retailers’ ordering decisions and analyse the benefits of issuing product-specific gift cards. We propose an optimal ordering model for retailers’ decision problems with gift cards being issued. We also solve the problem with the analytical forms of optimal order quantities and expected profits. By comparing the results with the classical newsvendor problem, we classify the benefits of issuing gift cards into three categories: (1) the demand stimulating; (2) the pre-payment, and (3) the non-redemption. We step further to explore a retailer's problem on how to determine the optimal discount for gift cards, which is characterized by a joint optimal policy on the ordering quantity and the discount. We derive the optimal condition on this joint policy. Numerical examples are conducted to illustrate the model results and analyse the influences of parameters. A sample average approximation method is also been introduced to solve the optimization model.

  • 64138.
    Zhang, Shengzhi
    et al.
    Florida Institute of Technology, Melbourne, FL.
    Makke, Omar
    Ford Motor, Detroit, MI.
    Gusikhin, Oleg Yu
    Ford Motor, Detroit, MI.
    Shah, Ayush
    Ford Motor, Detroit, MI.
    Vasilakos, Athanasios
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    A security model for dependable vehicle middleware and mobile applications connection2018In: VEHITS 2018: Proceedings of the 4th International Conference on Vehicle Technology and Intelligent Transport Systems / [ed] Gusikhin O.,Helfert M., 2018, p. 379-386Conference paper (Refereed)
    Abstract [en]

    Nowadays automotive industry has been working on the connectivity between automobile and smartphones, e.g., Ford’s SmartDeviceLink, MirrorLink, etc. However, as the interoperability between the smartphone and automotive system increase, the security concern of the increased attack surface bothers the automotive industry as well as the security community. In this paper, we thoroughly study the attack vectors against the novel connection framework between automobile and smartphones, and propose a generic security model to implement a dependable connection to eliminate the summarized attack vectors. Finally, we present how our proposed model can be integrated into existing automotive framework, and discuss the security benefits of our model. Copyright

  • 64139.
    Zhang, Shuangsheng
    et al.
    School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou, China.Xuzhou Urban Water Resources Management Office, Xuzhou, China.
    Liu, Hanhu
    School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou, China..
    Qiang, Jing
    School of Mathematics, China University of Mining and Technology, Xuzhou, China.
    Gao, Hongze
    GHD Services, Inc, Waterloo, Ontario, Canada.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lin, Jing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Optimization of Well Position and Sampling Frequency for Groundwater Monitoring and Inverse Identification of Contamination Source Conditions Using Bayes’ Theorem2019In: CMES - Computer Modeling in Engineering & Sciences, ISSN 1526-1492, E-ISSN 1526-1506, Vol. 119, no 2, p. 373-394Article in journal (Refereed)
    Abstract [en]

    Coupling Bayes’ Theorem with a two-dimensional (2D) groundwater solute advection-diffusion transport equation allows an inverse model to be established to identify a set of contamination source parameters including source intensity (M ), release location ( X0 , Y0) and release time (T0), based on monitoring well data. To address the issues of insufficient monitoring wells or weak correlation between monitoring data and model parameters, a monitoring well design optimization approach was developed based on the Bayesian formula and information entropy. To demonstrate how the model works, an exemplar problem with an instantaneous release of a contaminant in a confined groundwater aquifer was employed. The information entropy of the model parameters posterior distribution was used as a criterion to evaluate the monitoring data quantity index. The optimal monitoring well position and monitoring frequency were solved by the two-step Monte Carlo method and differential evolution algorithm given a known well monitoring locations and monitoring events. Based on the optimized monitoring well position and sampling frequency, the contamination source was identified by an improved Metropolis algorithm using the Latin hypercube sampling approach. The case study results show that the following parameters were obtained: 1) the optimal monitoring well position (D) is at (445, 200); and 2) the optimal monitoring frequency (Δt) is 7, providing that the monitoring events is set as 5 times. Employing the optimized monitoring well position and frequency, the mean errors of inverse modeling results in source parameters (M, X0 ,Y0 ,T0 ) were 9.20%, 0.25%, 0.0061%, and 0.33%, respectively. The optimized monitoring well position and sampling frequency can effectively safeguard the inverse modeling results in identifying the contamination source parameters. It was also learnt that the improved Metropolis-Hastings algorithm (a Markov chain Monte Carlo method) can make the inverse modeling result independent of the initial sampling points and achieves an overall optimization, which significantly improved the accuracy and numerical stability of the inverse modeling results.

  • 64140.
    Zhang, Shunli
    Luleå tekniska universitet.
    Materials recycling of electronic scrap by physical separation1997Licentiate thesis, comprehensive summary (Other academic)
  • 64141.
    Zhang, Shunli
    Luleå tekniska universitet.
    Recycling and processing of end-of-life electric and electronic equipment: fundamentals and applications1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents a concept of scrapology of end-of-life electric and electronic equipment (EOL EEE) as a basis on which to develop effective recycling techniques. Various study approaches associated with this concept are detailed in this thesis. In addition, the present work investigates materials separation techniques, in particular eddy current separation (ECS) technology. Based on our research work, a number of novel design alternatives for further developing ECS have been proposed. Major challenges encountered in processing and recycling of EOL EEE are discussed. The main results obtained in this study should be helpful in designing, implementing and improving a recycling system for EOL EEE.

  • 64142.
    Zhang, Shunli
    et al.
    Luleå tekniska universitet.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Cable and wire scrap recycling by physical separation technologies1998In: Environmental & Waste Management, ISSN 1460-5147, Vol. 1, no 3, p. 189-202Article in journal (Refereed)
    Abstract [en]

    For cable and wire scrap recycling, physical separation technologies can offer a solution that is both environmentally friendly and economically viable. It is clear that such toxic emissions as hydrogen chloride and chlorine gases resulting from burning polyvinyl chloride (PVC) can be avoided, and that both metals and plastics can be recovered and reused. In this paper, physical separation techniques employed in the cable and wire scrap recycling industry throughout the world are described. A critical comparison of various separation techniques has been made. It appears that density-based separation techniques, in particular, air tables have been implemented extensively in this specific recycling industry world-wide. However, many other separation techniques capable of recycling cable and wire scrap have also been developed with a view towards improving separation selectivity (product quality), while maintaining a sufficient level of materials recovery. Of these, it seems that electrodynamic or high tension separation techniques remain to be developed by designing new electrode systems

  • 64143.
    Zhang, Shunli
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Intelligent liberation and classification of electronic scrap1999In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 105, no 1, p. 295-301Article in journal (Refereed)
    Abstract [en]

    Mechanical recycling of electronic scrap oriented towards overall materials recovery from obsolete electronics is being implemented worldwide. The main reason is that the amount of electronic scrap is increasing and that the content of the precious metals present is decreasing. In this context, an effective liberation of various materials like metals and plastics is a crucial step towards mechanical separation. In addition, classification of electronic scrap is also important to be able to provide an appropriate feed material for the subsequent separation process. In the present study, liberation and its impact on the separation of personal computer (PC) scrap and printed circuit board (PCB) scrap has been investigated in detail. A special equipment functioning as a shape separator and an aspirator was used for the classification of electronic scrap.

  • 64144. Zhang, Shunli
    et al.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mechanical recycling of electronics scrap: the current status and prospects1998In: Waste Management & Research, ISSN 0734-242X, E-ISSN 1096-3669, Vol. 16, no 2, p. 119-128Article in journal (Refereed)
    Abstract [en]

    Of the various mechanical metal recycling techniques employed in electronic scrap processing, air table separation, magnetic separation and eddy current separation technolo gies have proved to be the most commercially successful. In addition, it is very important, even indispensable, that, prior to the physical processing of electronic scrap, selective dis mantling and identification (if necessary) be employed. It is, however, recognized that problems such as process optimiza tion and organics handling remain and that in-depth charac terization of electronic scrap will be essential in this context.

  • 64145.
    Zhang, Shunli
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mechanical separation-oriented characterization of electronic scrap1997In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 21, no 4, p. 247-269Article in journal (Refereed)
    Abstract [en]

    The ever-increasing amount of electronic scrap and the steadily-decreasing contents of the precious metals used in electronics, as well as the ever-growing environmental awareness, challenges such conventional precious-metal-oriented recycling techniques as pyrometallurgy. Separation and beneficiation of various materials encountered in electronic scrap might provide a correct solution ahead. In this context, mechanical separation-oriented characterization of electronic scrap was conducted in an attempt to evaluate the amenability of mechanical separation processes. Liberation degrees of various metals from the non-metals, which are crucial for mechanical separation, were analyzed by means of a grain counting approach. It is found that the metallic particles below 2 mm achieve almost complete liberation. Particle shapes were also quantified through an image processing system. The results obtained show that the shapes of the particles, as a result of shredding, turn out to be heterogeneous, thereby complicating mechanical separation processes. In addition, separability of various materials was ascertained by a sink–float analysis. It has been shown that density-based separation techniques shall be viable in separating metals from plastics, light plastics (ABS, PS and PVC, etc.) from glass fiber reinforced resins and aluminum from heavy metals. Specifically, a high quality copper concentrate can be expected by density-based separation techniques. Moreover, FT-IR spectra of plastics pieces from the light fractions after the sink–float testing show that PC scrap primarily contains ABS, PS and PVC plastics with the density range of +1.0–1.5 g/cm3, whereas PCB scrap mainly contains glass fiber reinforced epoxy resins plastics with the density range of +1.5–2.0 g/cm3.

  • 64146.
    Zhang, Shunli
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Optimization of electrodynamic separation for metals recovery from electronic scrap1998In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 22, no 3-4, p. 143-162Article in journal (Refereed)
    Abstract [en]

    The performance of an electrodynamic separator has been optimized in the present study for metals recovery from electronic scrap. Eight variables involved in the system was investigated by a 2IV8-4 fractional factorial design in an attempt to determine the significant variables. The effects of those variables were detailed with glass, polyvinyl chloride (PVC) as a representative of plastics, copper wires, copper and aluminum granulates. For various binary mixtures of copper wires and glass or PVC plastic, the electrodynamic separator is able to produce copper products with the grade ranging from 93 to 99%, and recovery from 95 to 99%, respectively, under the optimized conditions. Further, one sample which is a middling fraction resulting from air table separation was also tested. For a single pass, copper and aluminum was upgraded approximately from 11 and 7% to 34 and 22%, while maintaining the corresponding recovery of 87 and 99%, respectively.

  • 64147.
    Zhang, Shunli
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Arvidson, Bo
    Moss, William
    Investigation of the parameters of rotating drum type eddy current separators1998In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 27, no 6, p. 253-260Article in journal (Refereed)
    Abstract [en]

    Rotating eddy current separators are increasingly used in waste processing industries, particularly in the automobile and electric scrap recycling, for recovery of non-ferrous metals. If misused, however, a substantial loss of the metal values can incur. A deeper understanding of the influences of a large number of parameters involved in the eddy current separation system is of great help in optimizing the performance of an eddy current separator. In the present study, a rotating drum-type High-Force eddy current separator, has been investigated extensively with a wide range of materials including aluminum, copper, brass, zinc, lead and polyvinyl chloride (PVC). The results obtained show that the material-related variables like particle size and shape play a critical role in maximizing the deflections of the metal particles, implying that an effective liberation of the materials to be recovered is crucial. Further, the machine-related variables like rotational frequency and positioning of the magnetic field are of great importance. It appears that, for a given conductor, the deflection is proportional to the rotational frequency of the magnetic field.

  • 64148.
    Zhang, Shunli
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Arvidson, Bo R.
    Current status of eddy current separation1998In: Erzmetall, ISSN 0044-2658, Vol. 51, no 12, p. 829-836Article in journal (Refereed)
    Abstract [en]

    he three-stage evolution of eddy current separation with the equipment and applications is critically analyzed in this paper, with the third stage of development highlighted. It can be concluded that the eddy current separators of generation III are associated with the development of the magnetic roll system design which includes the magnet configuration in a magnetic roll, the magnetic roll configuration in a separator, and the eddy current induction regimes. With a continuing improvement of the magnetic roll system design, it is expected that the eddy current separators of the next generation will be widely applied in the recycling industry.

  • 64149.
    Zhang, Shunli
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Arvidson, Bo R.
    International Process Systems, Inc., Golden, CO.
    Moss, William
    International Process Systems, Inc., Golden, CO.
    Aluminum recovery from electronic scrap by High-Force R eddy-current separators1998In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 23, no 4, p. 225-241Article in journal (Refereed)
    Abstract [en]

    The amount of electronic scrap which contains a substantial portion of non-ferrous metals, primarily copper and aluminum, has been growing. The present study is directed toward aluminum recovery by a newly developed eddy current separator. The investigation on shredded personal computer and printed circuit board scrap demonstrates that the High-Force® eddy-current separator will be applicable for this purpose. It has been shown that, by a single pass of the materials on the High-Force® eddy-current separator, an aluminum concentrate out of personal computer scrap can be obtained with a purity of 85%, while maintaining a recovery in excess of 90%, with the feed rate being up to 0.3 kg/min.

  • 64150.
    Zhang, Shunli
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Arvidsson, Bo R.
    International Process Systems, Inc., Golden, CO.
    Moss, William
    International Process Systems, Inc., Golden, CO.
    Separation mechanisms and criteria of a rotating eddy-current separator operation1999In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 25, no 3, p. 215-232Article in journal (Refereed)
    Abstract [en]

    Much work has so far been done for modelling the magnetic deflecting (repulsive) force of eddy current separators. However, selective separation of various materials by eddy current separation depends not only on magnetic deflecting forces but also on competing forces like the gravitational force and the centrifugal force. Co-acting forces on a particle leaving the external drum are analyzed and evaluated in this study. Separation mechanisms of metal/non-metal and metal/metal separation systems have been investigated by a newly-developed High-Force® eddy-current separator. Further, a separation model governing an effective separation among various materials is presented. Based on this separation model, four practical separation criteria for metal/metal separation systems are put forward and have been substantiated experimentally.

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