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  • 20901. Xu, T
    et al.
    Jacobsen, G
    RISE, Swedish ICT, Acreo.
    Popov, S
    Li, J
    RISE, Swedish ICT, Acreo.
    Vanin, E
    RISE, Swedish ICT, Acreo.
    Wang, K
    Friberg, AT
    Zhang, Y
    RISE, Swedish ICT, Acreo.
    Chromatic dispersion compensation in coherent transmission system using digital filters2010In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, p. 16243-57Article in journal (Refereed)
  • 20902. Xu, T
    et al.
    Jacobsen, G
    RISE, Swedish ICT, Acreo.
    Popov, S
    Li, J
    RISE, Swedish ICT, Acreo.
    Wang, K
    Friberg, A T
    Normalized LMS digital filter for chromatic dispersion equalization in 112-Gbit/s, PDM-QPSK coherent optical transmission system2010In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, p. 963-7Article in journal (Refereed)
  • 20903.
    Xu, Tianhua
    et al.
    University College London (UCL), UK.
    Bayvel, Polina
    University College London (UCL), UK.
    Liu, Tiegen
    Tianjin University, China.
    Zhang, Yima
    Tianjin University, China.
    Jacobsen, Gunnar
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Li, Jie
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Carrier phase estimation in dispersion-unmanaged optical transmission systems2017In: Proceedings of 2017 IEEE 2nd Advanced Information Technology, Electronic and Automation Control Conference, IAEAC 2017, 2017, p. 1860-1864Conference paper (Refereed)
    Abstract [en]

    The study on carrier phase estimation (CPE) approaches, involving a one-tap normalized least-mean-square (NLMS) algorithm, a block-wise average algorithm, and a Viterbi-Viterbi algorithm has been carried out in the long-haul high-capacity dispersion-unmanaged coherent optical systems. The close-form expressions and analytical predictions for bit-error-rate behaviors in these CPE methods have been analyzed by considering both the laser phase noise and the equalization enhanced phase noise. It is found that the Viterbi-Viterbi algorithm outperforms the one-tap NLMS and the block-wise average algorithms for a small phase noise variance (or effective phase noise variance), while the three CPE methods converge to a similar performance for a large phase noise variance (or effective phase noise variance). In addition, the differences between the three CPE approaches become smaller for higher-level modulation formats.

  • 20904.
    Xu, Tianhua
    et al.
    University of Warwick, UK.
    Jacobsen, Gunnar
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Li, Jie
    RISE - Research Institutes of Sweden, ICT, Acreo. University of Warwick, UK.
    Leeson, Mark
    University of Warwick, UK.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden .
    Dynamic physical layer equalization in optical communication networks2018In: Optoelectronics and Advanced Materials Rapid Communications, ISSN 1842-6573, E-ISSN 2065-3824, Vol. 12, no 5-6, p. 292-298Article in journal (Refereed)
    Abstract [en]

    In optical transport networks, signal lightpaths between two terminal nodes can be different due to current network conditions. Thus the transmission distance and accumulated dispersion in the lightpath cannot be predicted. Therefore, the adaptive compensation of dynamic dispersion is necessary in such networks to enable flexible routing and switching. In this paper, we present a detailed analysis on the adaptive dispersion compensation using the least-mean-square (LMS) algorithm in coherent optical communication networks. It is found that the variable-step-size LMS equalizer can achieve the same performance with a lower complexity, compared to the traditional LMS algorithm. © 2018, National Institute of Optoelectronics. All rights reserved.

  • 20905.
    Xu, Tianhua
    et al.
    University College London, UK; KTH Royal Institute of Technology, Sweden.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo. KTH The Royal Institute of Technology, Sweden.
    Popov, Sergei
    KTH The Royal Institute of Technology, Sweden.
    Li, Jie
    RISE, Swedish ICT, Acreo.
    Liu, Tiegen
    Tianjin University, China.
    Zhang, Yimo
    Tianjin University, China.
    Close-form expression of one-tap normalized LMS carrier phase recovery in optical communication systems2016In: Proceedings of SPIE: Fourth International Conference on Wireless and Optical Communications, 2016, Vol. 9902, article id 990203Conference paper (Refereed)
    Abstract [en]

    The performance of long-haul high speed coherent optical fiber communication systems is significantly degraded by the laser phase noise and the equalization enhanced phase noise (EEPN). In this paper, the analysis of the one-tap normalized least-mean-square (LMS) carrier phase recovery (CPR) is carried out and the close-form expression is investigated for quadrature phase shift keying (QPSK) coherent optical fiber communication systems, in compensating both laser phase noise and equalization enhanced phase noise. Numerical simulations have also been implemented to verify the theoretical analysis. It is found that the one-tap normalized least-mean-square algorithm gives the same analytical expression for predicting CPR bit-error-rate (BER) floors as the traditional differential carrier phase recovery, when both the laser phase noise and the equalization enhanced phase noise are taken into account.

  • 20906.
    Xu, Tianhua
    et al.
    University College London, UK; Tianjin University, China.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Li, Jie
    RISE, Swedish ICT, Acreo.
    Liu, Tiegen
    Tianjin University, China.
    Zhang, Yimo
    Tianjin University, China.
    Bayvel, Polina
    University College London, UK.
    Analytical investigations on carrier phase recovery in dispersion-unmanaged n-PSK coherent optical communication systems2016In: Photonics, ISSN 2304-6732, Vol. 3, no 4, article id 51Article in journal (Refereed)
    Abstract [en]

    Using coherent optical detection and digital signal processing, laser phase noise and equalization enhanced phase noise can be effectively mitigated using the feed-forward and feed-back carrier phase recovery approaches. In this paper, theoretical analyses of feed-back and feed-forward carrier phase recovery methods have been carried out in the long-haul high-speed n-level phase shift keying (n-PSK) optical fiber communication systems, involving a one-tap normalized least-mean-square (LMS) algorithm, a block-wise average algorithm, and a Viterbi-Viterbi algorithm. The analytical expressions for evaluating the estimated carrier phase and for predicting the bit-error-rate (BER) performance (such as the BER floors) have been presented and discussed in the n-PSK coherent optical transmission systems by considering both the laser phase noise and the equalization enhanced phase noise. The results indicate that the Viterbi-Viterbi carrier phase recovery algorithm outperforms the one-tap normalized LMS and the block-wise average algorithms for small phase noise variance (or effective phase noise variance), while the one-tap normalized LMS algorithm shows a better performance than the other two algorithms for large phase noise variance (or effective phase noise variance). In addition, the one-tap normalized LMS algorithm is more sensitive to the level of modulation formats.

  • 20907.
    Xu, Tianhua
    et al.
    University College London, UK; KTH Royal Institute of Technology, Sweden; Tianjin University, China.
    Jacobsen, Gunnar
    RISE - Research Institutes of Sweden, ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Popov, Sergei
    Li, Jie
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sergeyev, Sergey
    Aston University, UK.
    Friberg, Ari T.
    KTH Royal Institute of Technology, Sweden; Aston University, UK.
    Liu, Teigen
    Tianjin University, China.
    Zhang, Yimo
    Tianjin University, China.
    Analysis of chromatic dispersion compensation and carrier phase recovery in long-haul optical transmission system influenced by equalization enhanced phase noise2017In: Optik (Stuttgart), ISSN 0030-4026, E-ISSN 1618-1336, Vol. 138, p. 494-508Article in journal (Refereed)
    Abstract [en]

    The performance of long-haul coherent optical fiber transmission system is significantly affected by the equalization enhanced phase noise (EEPN), due to the interaction between the electronic dispersion compensation (EDC) and the laser phase noise. In this paper, we present a comprehensive study on different chromatic dispersion (CD) compensation and carrier phase recovery (CPR) approaches, in the n-level phase shift keying (n-PSK) and the n-level quadrature amplitude modulation (n-QAM) coherent optical transmission systems, considering the impacts of EEPN. Four CD compensation methods are considered: the time-domain equalization (TDE), the frequency-domain equalization (FDE), the least mean square (LMS) adaptive equalization are applied for EDC, and the dispersion compensating fiber (DCF) is employed for optical dispersion compensation (ODC). Meanwhile, three carrier phase recovery methods are also involved: a one-tap normalized least mean square (NLMS) algorithm, a block-wise average (BWA) algorithm, and a Viterbi-Viterbi (VV) algorithm. Numerical simulations have been carried out in a 28-Gbaud dual-polarization quadrature phase shift keying (DP-QPSK) coherent transmission system, and the results indicate that the origin of EEPN depends on the choice of chromatic dispersion compensation methods, and the effects of EEPN also behave moderately different in accordance to different carrier phase recovery scenarios.

  • 20908.
    Xu, Tianhua
    et al.
    Tianjin University, China; University College London, UK; KTH Royal Institute of Technology, Sweden.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Li, Jie
    RISE, Swedish ICT, Acreo.
    Sergeyev, Sergey
    Aston University, UK.
    Friberg, Ari T.
    KTH Royal Institute of Technology, Sweden.
    Zhang, Yimo
    Tianjin University, China.
    Analytical BER performance in differential n-PSK coherent transmission system influenced by equalization enhanced phase noise2015In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 334, p. 222-227Article in journal (Refereed)
    Abstract [en]

    Long-haul high speed optical transmission systems are significantly distorted by the interplay between the electronic chromatic dispersion (CD) equalization and the local oscillator (LO) laser phase noise, which leads to an effect of equalization enhanced phase noise (EEPN). The EEPN degrades the performance of optical communication systems severely with the increment of fiber dispersion, LO laser linewidth, symbol rate, and modulation format. In this paper, we present an analytical model for evaluating the performance of bit-error-rate (BER) versus signal-to-noise ratio (SNR) in the n-level phase shift keying (n-PSK) coherent transmission system employing differential carrier phase estimation (CPE), where the influence of EEPN is considered. Theoretical results based on this model have been investigated for the differential quadrature phase shift keying (DQPSK), the differential 8-PSK (D8PSK), and the differential 16-PSK (D16PSK) coherent transmission systems. The influence of EEPN on the BER performance in term of the fiber dispersion, the LO phase noise, the symbol rate, and the modulation format are analyzed in detail. The BER behaviors based on this analytical model achieve a good agreement with previously reported BER floors influenced by EEPN. Further simulations have also been carried out in the differential CPE considering EEPN. The results indicate that this analytical model can give an accurate prediction for the DQPSK system, and a leading-order approximation for the D8PSK and the D16PSK systems.

  • 20909.
    Xu, Tianhua
    et al.
    University College London, UK.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Liu, Tiegen
    Tianjin University, China.
    Zhang, Yimo
    Tianjin University, China.
    Bayvel, Polina
    University College London, UK.
    Analytical estimation in differential optical transmission systems influenced by equalization enhanced phase noise2016In: 2016 Progress in Electromagnetic Research Symposium (PIERS), 2016, p. 4844-4848, article id 7735770Conference paper (Refereed)
    Abstract [en]

    An analytical model is presented for assessing the performance of the bit-error-rate (BER) in the differential m-level phase shift keying (m-PSK) transmission systems, where the influence of equalization enhanced phase noise (EEPN) has been considered. Theoretical analysis has been carried out in differential quadrature phase shift keying (DQPSK), differential 8-PSK (D8PSK), and differential 16-PSK (D16PSK) optical transmission systems. The influence of EEPN on the BER performance, in term of signal-to-noise ratio (SNR), are investigated for different fiber dispersion, LO laser linewidths, symbol rates, and modulation formats. Our analytical model achieves a good agreement with previously reported EEPN induced BER floors, and can give an accurate prediction for the DQPSK system, and a leading-order approximation for the D8PSK and the D16PSK systems.

  • 20910.
    Xu, Tianhua
    et al.
    Tianjin University, China; University of Warwick, UK; University College London, UK.
    Jin, Cenqin
    University of Warwick, UK.
    Zhang, Shuqing
    Harbin Institute of Technology, China.
    Jacobsen, Gunnar
    RISE - Research Institutes of Sweden, ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Leeson, Mark
    University of Warwick, UK.
    Liu, Tiegen
    Tianjin University, China.
    Phase noise cancellation in coherent communication systems using a radio frequency pilot tone2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 21, article id 4717Article in journal (Refereed)
    Abstract [en]

    Long-haul optical fiber communication employing digital signal processing (DSP)-based dispersion compensation can be distorted by the phenomenon of equalization-enhanced phase noise (EEPN), due to the reciprocities between the dispersion compensation unit and the local oscillator (LO) laser phase noise (LPN). The impact of EEPN scales increases with the increase of the fiber dispersion, laser linewidths, symbol rates, signal bandwidths, and the order of modulation formats. In this work, the phase noise cancellation (PNC) employing a radio frequency (RF) pilot tone in coherent optical transmission systems has been investigated. A 28-Gsym/s QPSK optical transmission system with a significant EEPN has been implemented, where the carrier phase recovery (CPR) was realized using the one-tap normalized least-mean-square (NLMS) estimation and the differential phase detection (DPD), respectively. It is shown that the RF pilot tone can entirely eliminate the LPN and efficiently suppress the EEPN when it is applied prior to the CPR. © 2019 by the authors. 

  • 20911.
    Xu, Tianhua
    et al.
    Tianjin University, China; University College London, UK; KTH Royal Institute of Technology, Sweden.
    Li, Jie
    RISE, Swedish ICT, Acreo.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Djupsjöbacka, Anders
    RISE, Swedish ICT, Acreo.
    Schatz, Richard
    KTH Royal Institute of Technology, Sweden.
    Zhang, Yimo
    RISE, Swedish ICT, Acreo.
    Bayvel, Polina
    University College London, UK.
    Field trial over 820km installed SSMF its potential Terabit/s super channel application with up to 57.5-Gbaud DP-QPSK transmission2015In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 353, p. 133-138Article in journal (Refereed)
    Abstract [en]

    In this paper, we report the result of a field trial of 56-Gbaud (224-Gbit/s) and 57.5-Gbaud (230-Gbit/s) dual-polarization quadrature phase shift keying (DP-QPSK) coherent optical transmission over 820 km installed standard single mode fiber (SSMF). Offline digital signal processing (DSP) was applied for signal recovery and bit-error-rate (BER) counting in our field trial experiments, and BER performance well below the 7% overhead hard-decision forward error correction (FEC) error-free threshold (4.5×10−3) at 231-1 pseudo random bit sequence (PRBS) pattern length has been achieved, with the best achievable BERs of 2×10−4 (56-Gbaud) and 3×10−4 (57.5-Gbaud), respectively. In parallel a 1.15-Tbit/s (5×230-Gbit/s) quasi-Nyquist spaced wavelength division multiplexing (WDM) superchannel transmission over the same 820 km optical field link (FL) was also investigated through numerical simulations based on the same 57.5-Gbaud DP-QPSK signal using 1% roll-off Nyquist pulse shaping with 60-GHz channel spacing, and the results indicate that the BER performance well below the 7% overhead hard-decision FEC error-free threshold (4.5×10−3) for the 1.15-Tbit/s DP-QPSK superchannel transmission can be achieved.

  • 20912.
    Xu, Tianhua
    et al.
    Tianjin Universtiy, China.
    Liu, Tiegen
    Tianjin Universtiy, China.
    Zhang, Yimo
    Tianjin Universtiy, China.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo.
    Li, Jie
    RISE, Swedish ICT, Acreo.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Digital Adaptive Carrier Phase Estimation in Multi-level Phase Shift Keying Coherent Optical Communication Systems2016In: 2016 3rd International Conference on Information Science and Control Engineering (ICISCE), 2016, p. 1293-1297, article id 7726373Conference paper (Refereed)
    Abstract [en]

    The analysis of adaptive carrier phase estimation is investigated in long-haul high speed n-level phase shift keying (n-PSK) optical fiber communication systems based on the one-tap normalized least-mean-square (LMS) algorithm. The close-form expressions for the estimated carrier phase and the bit-error-rate floor have been derived in the n-PSK coherent optical transmission systems. The results show that the one-tap normalized LMS algorithm performs pretty well in the carrier phase estimation, but will be less effective with the increment of modulation levels, in the compensation of both intrinsic laser phase noise and equalization enhanced phase noise.

  • 20913. Xuan, Y
    et al.
    Sandberg, Mats
    RISE, Swedish ICT, Acreo.
    Berggren, M
    Crispin, X
    An all-polymer-air PEDOT battery2012In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 13, p. 623-7Article in journal (Refereed)
  • 20914.
    Xue, Lei
    et al.
    Chalmers University of Technology, Sweden; Shanghai Jiao Tong University, China .
    Yi, Lilin
    Shanghai Jiao Tong University, China .
    Zhang, Lu
    KTH Royal Institute of Technology, Sweden; Shanghai Jiao Tong University, China .
    Ozolins, Oskars
    RISE - Research Institutes of Sweden, ICT, Acreo. KTH Royal Institute of Technology, Sweden .
    Udalcovs, Aleksejs
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Pang, Xiaodan
    RISE - Research Institutes of Sweden, ICT, Acreo. Infinera, Sweden.
    Chen, Jiajia
    KTH Royal Institute of Technology, Sweden .
    50-Gb/s Dispersion-unmanaged DMT Transmission with Injection Locked 10G-class 1.55-μm DML2019In: Conference on Lasers and Electro-Optics OSA Technical Digest (Optical Society of America, 2019), paper SW4O.2, OSA - The Optical Society , 2019, article id SW4O.2Conference paper (Refereed)
    Abstract [en]

    We demonstrate 50-Gb/s DMT signal transmission over 20-km SMF by using a 10G-class 1.55-μm DML without optical dispersion compensation. Injection locking technique is introduced, which doubles system bandwidth and greatly suppresses DML chirp. © 2019 The Author(s)

  • 20915.
    Xue, Li
    et al.
    Chinese Academy of Sciences, China.
    Liu, Gang
    University of Southern Denmark, Denmark.
    Parfitt, Julian
    Anthesis Group, UK.
    Liu, Xiaojie
    Chinese Academy of Sciences, China.
    Van Herpen, Erica
    Wageningen University, The Netherlands.
    Stenmarck, Åsa
    IVL Swedish Environmental Research Institute, Sweden.
    O'Connor, Clementine
    World Resources Institute, USA.
    Östergren, Karin
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Cheng, Shengkui
    Chinese Academy of Sciences, China.
    Missing Food, Missing Data?: A Critical Review of Global Food Losses and Food Waste Data2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, no 12, p. 6618-6633Article in journal (Refereed)
    Abstract [en]

    Food losses and food waste (FLW) have become a global concern in recent years and emerge as a priority in the global and national political agenda (e.g., with Target 12.3 in the new United Nations Sustainable Development Goals). A good understanding of the availability and quality of global FLW data is a prerequisite for tracking progress on reduction targets, analyzing environmental impacts, and exploring mitigation strategies for FLW. There has been a growing body of literature on FLW quantification in the past years; however, significant challenges remain, such as data inconsistency and a narrow temporal, geographical, and food supply chain coverage. In this paper, we examined 202 publications which reported FLW data for 84 countries and 52 individual years from 1933 to 2014. We found that most existing publications are conducted for a few industrialized countries (e.g., the United Kingdom and the United States), and over half of them are based only on secondary data, which signals high uncertainties in the existing global FLW database. Despite these uncertainties, existing data indicate that per-capita food waste in the household increases with an increase of per-capita GDP. We believe that more consistent, in-depth, and primary-data-based studies, especially for emerging economies, are badly needed to better inform relevant policy on FLW reduction and environmental impacts mitigation.

  • 20916.
    Xue, Li
    et al.
    Chinese Academy of Sciences, China; University of Southern Denmark, Denmark; University of Chinese Academy of Sciences, China.
    Prass, Neele
    University of Southern Denmark, Denmark.
    Gollnow, Sebastian
    University of Natural Resources and Life Sciences, Austria.
    Davis, Jennifer
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Scherhaufer, Silvia
    University of Natural Resources and Life Sciences, Austria.
    Östergren, Karin
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Cheng, Shengkui
    Chinese Academy of Sciences, China.
    Liu, Gang
    University of Southern Denmark, Denmark.
    Efficiency and Carbon Footprint of the German Meat Supply Chain2019In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 53, no 9, p. 5133-5142Article in journal (Refereed)
    Abstract [en]

    Meat production and consumption contribute significantly to environmental impacts such as greenhouse gas (GHG) emissions. These emissions can be reduced via various strategies ranging from production efficiency improvement to process optimization, food waste reduction, trade pattern change, and diet structure change. On the basis of a material flow analysis approach, we mapped the dry matter mass and energy balance of the meat (including beef, pork, and poultry) supply chain in Germany and discussed the emission reduction potential of different mitigation strategies in an integrated and mass-balance consistent framework. Our results reaffirmed the low energy conversion efficiency of the meat supply chain (among which beef was the least efficient) and the high GHG emissions at the meat production stage. While diet structure change (either reducing the meat consumption or substituting meat by edible offal) showed the highest emissions reduction potential, eliminating meat waste in retailing and consumption and byproducts generation in slaughtering and processing were found to have profound effect on emissions reduction as well. The rendering of meat byproducts and waste treatment were modeled in detail, adding up to a net environmental benefit of about 5% of the entire supply chain GHG emissions. The combined effects based on assumed high levels of changes of important mitigation strategies, in a rank order considering the level of difficulty of implementation, showed that the total emission could be reduced by 43% comparing to the current level, implying a tremendous opportunity for sustainably feeding the planet by 2050.

  • 20917.
    Yakubov, Gleb E.
    et al.
    University of Queensland, Australia; Unilever, UK.
    Macakova, Lubica
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. Unilever, UK.
    Wilson, Stephen
    Unilever, UK.
    Windust, John H. C.
    Unilever, UK.
    Stokes, Jason R.
    Unilever, UK; University of Queensland, Australia.
    Aqueous lubrication by fractionated salivary proteins: Synergistic interaction of mucin polymer brush with low molecular weight macromolecules2015In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 89, p. 34-45Article in journal (Refereed)
    Abstract [en]

    The remarkable lubrication provided by saliva in the oral cavity is vital to human health and wellbeing. Yet, molecular mechanisms for saliva lubrication remain unclear. In this work we report a possible mechanism of synergistic interaction between salivary proteins. By isolating a number of salivary protein fractions, we identify major protein candidates that contribute to saliva lubrication. We discover that a key driver for low friction is a hydrated brush-like layer formed by glycosylated species, with an essential synergistic contribution coming from the low molecular weight components that facilitate spreading, adsorption and strengthening of the salivary film on hydrophobic substrates. Lessons may be learned from saliva for understanding other natural bio-aqueous lubrication systems and for the development of saliva mimics.

  • 20918.
    Yamamoto, Yuji
    et al.
    Mälardalen University, Sweden.
    Sandström, Kristian
    RISE - Research Institutes of Sweden, ICT, SICS.
    Munoz, Alvaro Aranda
    RISE - Research Institutes of Sweden, ICT, SICS.
    Karakuri iot - the concept and the result of pre-study2018In: Advances in Transdisciplinary Engineering, 2018, Vol. 8, p. 311-316Conference paper (Refereed)
    Abstract [en]

    Although scholars and practitioners are actively discussing the potential benefits of introducing Internet of Thing (IoT) in production, IoT is still as an expensive solution in terms of investment and high technological threshold. Manufacturing companies seek a simpler and lower-cost approach to adopting IoT technologies in production, allowing companies to take advantage of the knowledge and innovation capabilities of people close to shop floor operations. This paper introduces the concept of “Karakuri IoT” – simple and low-cost IoT-aided improvements driven by the people close to shop floor operations. A pre-study is conducted to examine the feasibility of the concept. This paper presents the results of the pre-study.

  • 20919. Yaminsky, VV
    et al.
    Claesson, PM
    YKI – Ytkemiska institutet.
    Eriksson, JC
    Wetting hysteresis and instability of hydrophobized glass and mica surfaces1993In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 161, p. 91-100Article in journal (Refereed)
    Abstract [en]

    Wetting of methylated glass and of Langmuir-Blodgett monolayer coated mica by water and ethanol-water mixtures was investigated by applying the Wilhelmy plate technique. A detailed characterization of the hydrophobized solid surfaces is achieved by a high-resolution continuous record of the wetting tension as a function of the position of the partly immersed plate, the speed of the immersion and retraction, and the time immersed. Among several nonequilibrium and irreversible phenomena studied are (i) static and dynamic wetting tension hysteresis, (ii) wetting tension relaxation and the attainment of equilibrium tension, (iii) desorption and/or reorientation effects at the three-phase contact line and at the solid-liquid interface, and (iv) electrification of solid surfaces on retraction from liquid. The layers produced by dimethyldichlorosilane on glass are stable in both water and ethanol. Dynamic and static wetting tensions are increased, and the equilibrium values are attained at shorter times with increasing alcohol content. The superimposed effect of electrostatic charging also diminishes on the transition from pure water to pure ethanol. Monolayers on mica are generally unstable and undergo degradation both at the three-phase contact line and at the interface with water (similar changes can be traced with composite silane layers on glass before extraction with ethanol). Wetting scanning reveals the changes of wetting tension along the plate arising from the instability of the hydrophobic layer. A rapid desorption of deposited Langmuir-Blodgett layers is observed on immersion in ethanol.

  • 20920. Yaminsky, VV
    et al.
    Yaminskaya, KB
    YKI – Ytkemiska institutet. KTH Royal Institute of Technology, Sweden.
    Thermodynamic analysis of solute effects on contact angles : Equilibrium adsorption of cationic surfactants at silica - water and silica - air interfaces1995In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 11, p. 936-941Article in journal (Refereed)
    Abstract [en]

    It is shown that the equilibrium wetting tension, defined thermodynamically as the difference between the solid -vapor and solid-liquid interfacial tensions, can be measured to the same high degree of certainty and accuracy as the surface tension of liquids. Just as for surface tension isotherms the wetting tension isotherms can be analyzed through the Gibbs adsorption equation. This allows for unambiguous evaluation of the adsorption difference at the two interfaces. As an example we have investigated the wetting of smooth and homogeneous silica glass surfaces by solutions of cetyltrimethylammonium bromide (CTAB). At small concentrations (below the point of zero charge) equilibrium monolayer adsorption is larger at the solid-vapor interface than at the solid-liquid interface. At higher concentrations (near the critical micelle concentration) the adsorption difference changes sign due to formation of bilayer at a solid-liquid interface. Adsorption reequilibration within the hydrophobic monolayer occurs when a three-phase contact line is displaced. This reequilibration is slow and explains large contact angle hysteresis typically observed when measurements are done under nonequilibrium conditions.

  • 20921.
    Yan, J.
    et al.
    Luleå University of Technology.
    Ryman, Christer
    RISE, Swerea, Swerea MEFOS.
    Wikström, Jan-Olov
    RISE, Swerea, Swerea MEFOS.
    Grip, C.-E.
    SSAB Tunnplåt AB.
    Preface2006In: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083, Vol. 3, no 2, p. 115-Article in journal (Refereed)
  • 20922. Yanez, JA
    et al.
    Laarz, E
    YKI – Ytkemiska institutet.
    Bergström, L
    YKI – Ytkemiska institutet.
    Viscoelastic properties of particle gels1999In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 209, p. 162-172Article in journal (Refereed)
    Abstract [en]

    The effect of strength of attraction and volume fraction on the mechanical properties of alumina particle networks were investigated. Alumina particle gels were formed reversibly and in situ in the rheometer by cooling alumina particle suspensions with adsorbed poly(12-hydroxy stearic acid) suspended in a marginal solvent, hexanol. The collapse of the polymer layer with decreasing solvency (temperature) induces flocculation when the long-range van der Waals force overcomes the remaining steric repulsion. The gelation temperature depends on volume fraction. At the gel temperature, Tgel, the gel becomes predominantly elastic; at temperatures below Tgel, the elasticity increases with decreasing temperature. We find that the elastic modulus data, measured over a wide range of volume fraction (0.2 < φ < 0.425) and temperature (10-14°C), follows: G = G0(φ - φg)s. This scaling suggests the prefactor and exponent to be independent of temperature. We present some arguments for why subjecting a particle gel to a preshear procedure might result in an temperature-dependent prefactor. By invoking such an effect, we are able to rescale and collapse previously published moduli data on presheared suspensions according to the (φ - φg) expression.

  • 20923. Yang, Jian
    et al.
    Carlsson, Jan
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Calculation of self impedance and radiation efficiency of a dipole near a lossy cylinder with arbitrary cross section by using the moment method and a spectrum of two-dimensional solutions2002In: Microwave and Optical Technology Letters, Vol. 32, no 2, p. 108-112Article in journal (Refereed)
  • 20924. Yang, Jian
    et al.
    Pivnenko, S.
    Laitinen, T.
    Carlsson, Jan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Elektronik, EMC.
    Chen, Xiaoming
    Measurements of Diversity Gain and Radiation Efficiency of the Eleven Antenna by using Different Measurement Techniques2010In: 4 th European Conference on Antennas and Propagation. Barcelona, Spain. 2010-04-12--16, EuCAP , 2010Conference paper (Refereed)
  • 20925.
    Yang, L.
    RISE, Innventia.
    A physical model for liquid movement into a porous substrate under the action of a pressure pulse2013In: Nordic Pulp and Paper Research Journal, ISSN 0283-2631 , no 1, p. 94-100Article in journal (Refereed)
  • 20926.
    Yang, L.
    RISE, Innventia.
    Improved methods for adjusting the uv content of measurement instrument illumination for papermaking industry2014In: Proceedings of SPIE - The International Society for Optical Engineering, 2014Conference paper (Refereed)
  • 20927. Yang, L
    et al.
    Fogden, A
    YKI – Ytkemiska institutet.
    Pauler, N
    Sävborg, Ö
    Kruse, B
    A novel method for studying ink penetration of a print2005In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 20, p. 423-430Article in journal (Refereed)
    Abstract [en]

    A method combining microscopy with image analysis for studying ink penetration of ink-jet prints has been proposed. Prints on paper substrates of various material compositions have been microtomed, imaged with optical microscopy, and analyzed with image processing. The penetration depth and distribution of the ink-jet dye in the paper, which depend on the material compositions of the substrates and printed ink volumes, are then obtained by means of statistical analysis. The study focuses on uncoated fine papers, including five types of hand-sheets and two commercial papers. It is observed that ink penetration can be significantly reduced by adding internal sizing (hydrophobizing) chemicals in the hand-sheet making, while it is relatively less affected by addition of filler and fluorescent whitening agent (FWA). Ink volume obviously influences the depth of its penetration, with depth increasing linearly for higher ink volumes but displaying a disproportionately shallow penetration for smaller applied volumes.

  • 20928. Yang, L
    et al.
    Fogden, A
    YKI – Ytkemiska institutet.
    Pauler, N
    Sävborg, Ö
    Kruse, B
    Studying ink penetration with microscopic and spectroscopic techniques2006In: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 50, p. 327-332Article in journal (Refereed)
    Abstract [en]

    Distribution of ink jet ink in paper substrates and the consequences of ink penetration for printing color reproduction have been studied by combining microscopic image processing with spectroscopic analysis. The study focused on the effects of the composition of uncoated paper, for five laboratory papers plus two commercial products, all consisting of similar pulps but with different combinations of additives. In particular, it was observed that hydrophobizing internal size agents significantly reduced ink penetration, while their effect on paper optical properties was negligible. This observation thus made it possible to study experimentally the pure effects of ink penetration. Pairwise comparisons of prints on such laboratory papers with identical optical properties revealed remarkable impacts of ink penetration on optical density, causing color saturation reduction and color shift. These experimental observations confirmed the theoretical predictions.

  • 20929.
    Yang, Li
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Detailed analysis of the UV-adjustment techniques used in paper and graphic industries2017In: Color Research and Application, ISSN 0361-2317, E-ISSN 1520-6378, Vol. 42, no 1, p. 19-26Article in journal (Refereed)
    Abstract [en]

    Many commercial materials (papers and boards) contain optical brightening agents also known as fluorescent whitening agents. Adequate adjustment of the UV content of a measurement device (e.g., spectrophotometers) is essential for accurate color measurement. As specified in the ISO standards, the UV content is adjusted against an assigned value of an international reference transfer standard, for example, CIE whiteness (D65/10°) for the CIE illuminant D65 or ISO brightness for the C illuminant. Because of the simplicity, these approaches have gained great popularity in papermaking industry. Yet, there has been little evidence indicating how accurate the total spectral radiance factor corresponding to the single assigned value is reproduced. Hence, we present a method that quantitatively evaluates the accuracy of the UV-adjustment technique, through comparing the total spectral radiance factors obtained from UV adjustment with the assigned ones. This method has been applied to three second-level international reference transfer standard illuminated by three standard illuminants, D65, C, and D50. We found that the major differences between the assigned spectra and those obtained from the UV adjustments occur in the blue band where fluorescence is strong. At a few wavelengths, the differences may be up to 4-5%. Nevertheless, their color differences corresponding to the assigned spectra and those obtained from the UV adjustments are still smaller than unity (1 ΔE*) for all of the illumination conditions. Two instruments using the representative UV adjusting techniques, for example, the conventional UV-adjusting with an adjustable (GG395) UV filter and the numerical UV-filtering, have been studied.

  • 20930.
    Yang, Li
    RISE, Innventia.
    Ink dynamics and ink transfer under printing nip2012Conference paper (Refereed)
  • 20931.
    Yang, Li
    RISE, Innventia.
    Kubelka Munk model in paper optics: successes, limitations and improvements2011In: / [ed] Hirn, U., 2011, , p. 3Conference paper (Refereed)
  • 20932.
    Yang, Li
    RISE, Innventia.
    Optical measurements of paper and textile: Influences from the instrumental setups and the structural and surface characteristics2015In: 9th International paper and coating chemistry symposium, Tokyo, Japan, Oct 29, 2015Conference paper (Other academic)
    Abstract [en]

    Spectral reflectance, radiance factors, gloss etc of paper and textile are often regarded as intrinsic properties of the materials alone. But in practice, instrumental readings of these properties depend even on the instruments setups, for instance, illumination/detection geometries, UV contents of the illumination, measurement areas etc. Comparative studies with four commercial spectrophotometers of three illumination/detection geometries, Diffuse/0-deg, Diffuse/8-deg and 45-deg/0-deg, have been conducted. These geometries are used in paper, textile and graphic industries, respectively. The materials analysed in this study include white and colour papers and textiles. The white papers contain fluorescent whitening agents (FWAs) whose excitation energies are only in UV wavelength bands. On the contrary, the colour papers have fluorescent agents whose excitation energies are in the visible wavelength bands, according to our measurements. Textile reference standards of different whiteness values are also included in order to study the influences from surface texture. The study confirms the strong influences of instruments setups, e.g. illumination/detection geometries, UV contents of the light sources etc, on the measured results. The study also reveals the significant influences from the combination of instrumental setups with the structural and surface characteristics of the measured samples.

  • 20933.
    Yang, Li
    RISE, Innventia.
    Progress in intelligent packaging materials and technology2016Conference paper (Other academic)
  • 20934.
    Yang, Li
    et al.
    RISE, Innventia.
    Christiansson, Hans
    Spatially resolved analysis of print through and ink penetration of printed matters2015Conference paper (Other academic)
    Abstract [en]

    Print through is an often encountered defect of printed maters, especially on paper grades of low and medium grammages. Print through phenomena have two contributing components, show through and strike through, resulting from insufficient paper opacity and ink penetration, respectively. The existing measurement method of print through and its components are calculated from a set of spectral reflectance values of printed and non-printed paper samples. These reflectance values are from rather big areas that equal to the opening of the employed spectrophotometer (say 33 mm in diameter). Thus, the calculated print through, show through and strike through, are only average values of the measured areas. This method has intrinsic weaknesses as paper is an inhomogeneous medium whose structure and materials compositions vary from one position to another, leading to inhomogeneous show through and strike through (opacity and ink penetration) across the measured areas, especially for papers of low and medium grammages.In this report we present a new method that enables one to take into account of variations in print through across the measured areas. The method employs a scanner that scans the printed and unprinted samples into RGB images of desired spatial resolutions. With the help of calibration patches that are simultaneously scanned as the measured samples, the RGB image signals can be converted into reflectance values. These reflectance values are then used to compute the print through, show through and strike through. Moreover, by means of Kubelka-Munk model, the depth of ink penetration at each spatial position can also be obtained. The developed method has been implemented in Matlab and successfully been applied to printed samples of newsprint and office papers. Comparative studies between instrumental measurements and perceptual evaluations confirm that the print through variations across the printed areas have strong influences on the print quality assessments. It is also found that using internal size agents in paper making is helpful for reducing ink-penetration.

  • 20935.
    Yang, Li
    et al.
    RISE, Innventia.
    Hedberg, Viktoria
    Hagberg, Anni
    RISE, Innventia.
    Surface sizing for hybrid printing2012Conference paper (Refereed)
  • 20936.
    Yang, Li
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Karlsson, Max
    Uppsala University, Sweden.
    Effective method for fast and detailed analysis of holographic patterns over a large area2017In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 56, no 26, p. 7491-7497Article in journal (Refereed)
    Abstract [en]

    An effective method is proposed that enables one to simultaneously analyze details of numerous holographic grating patterns over a large area. Unlike the conventional approaches relying on sophisticated lighting and optical systems and dark environment, only a flatbed scanner is needed. Thanks to the “rotate-scan” measurement strategy, details of the holographic grating patterns can be obtained, e.g., spatial distribution of the grating patterns, interval and orientation of the grating grooves within each grating pattern, and defects of the holographic patterns. The method has been verified by applications to two holographic papers of different grating intervals and orientations. The measured values agree well with those obtained with a light optical microscope (LOM). The proposed method is applicable to both transparent and reflective holographic materials of broad grating periodicity.

  • 20937.
    Yang, Li
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy.
    Liu, J
    Beijing Institute of Graphic Communication, China.
    Wei, X
    Beijing Institute of Graphic Communication, China.
    A model of inkjet printing on porous substrates incorporating droplet impact2017In: 44th International Research Conference of iarigai: Proceedings / [ed] Gane P, Darmstadt: International Association of Research Organizations for the Information, Media and Graphic Arts Industrie (IARIGAI), 2017, Vol. 44, p. 3-6Conference paper (Refereed)
    Abstract [en]

    A model of inkjet printing dynamics has been developed that enables a comprehensive view to be obtained of the relationships between the characteristics of the ink droplet (volume, striking speed, viscosity and surface tension), substrate properties and interactions between the ink and the substrate. Simulations based on the three equations that are the major results of the model have provided an understanding of the basics of inkjet printing. Pressure profiles resulting from ink-striking by ink droplets of different volumes and jetting speeds have been obtained. The time duration of the striking process was in the order of microsecond and the peaks of the striking pressure were solely dependent on the jetting velocities, while the duration time of the striking processes was dependent only on the droplets volumes. The penetration length (depth) was heavily dependent on the contact angle. For a coated surface of small pores, the initial penetration depth was 0.26 micron when the striking speed was 30m/s. For a larger pore, the corresponding depth was 1.30 micron.

  • 20938.
    Yang, Li
    et al.
    RISE, Innventia.
    Liu, Jianghao
    Gu, Lingya
    Detailed insights to liquid absorption and liquid-paper interaction2013Conference paper (Refereed)
  • 20939.
    Yang, Li
    et al.
    RISE, Innventia.
    Thorman, Sofia
    RISE, Innventia.
    Teleman, Anita
    RISE, Innventia.
    Flexographic printability of packaging: challenges and new approaches2014Conference paper (Refereed)
  • 20940.
    Yang, Li
    et al.
    RISE, Innventia.
    Thorman, Sofia
    RISE, Innventia.
    Teleman, Anita
    RISE, Innventia.
    Study on flexpgraphic printability of packaging2014In: China Printing and Packaging Study, ISSN 1674-5752, Vol. 6, no 6, p. 1-3Article in journal (Other academic)
  • 20941.
    Yang, S-H.
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Analysis ofinteraction effects between WECs in four types of wave farms2018In: Advances in Renewable Energies Offshore - Proceedings of The 3rdInternational Conference on Renewable Energies Offshore (RENEW 2018),, 2018, p. 647-658Conference paper (Refereed)
    Abstract [en]

    The development of Wave Energy Converters (WECs) is often carried out based on detailed analysis of a single unit. However, successful prototypes that will become commercial will be installed inwave farms where additional effects due to interactions between the WECs will occur. The current study presents results from time-domain coupled simulations, which are used to calculate, among others, the Levelised Cost of Energy (LCoE) and fatigue lives of moorings of the WEC system. Four types of wave farms were compared using the same point-absorbing WEC but with different mooring designs and array patterns. The fatigue damage of the moorings was found to increase for the arrays with strong hydrodynamic interactions and mechanical couplings. The results show that the LCoE value for a WEC array farm is sensitive to the hydrodynamic interaction between WECs and the mechanical couplings in the mooring design.

  • 20942.
    Yang, Shun-Han
    et al.
    Chalmers Universtiy of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers Universtiy of Technology, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport, Safety. Chalmers University of Technology, Sweden.
    Parametric study of the mechanical characteristics of power cables under dynamic motions2015In: Proceedings of the 11th European Wave and Tidal Energy Conference (EWTEC 2015), 2015Conference paper (Refereed)
    Abstract [en]

    To maximise the harvesting of wave energy, solutions have been proposed that utilize wave energy converters (WECs) installed in arrays. This investigation presents a case study in which several WECs are located around a central hub, with each WEC connected to the hub by a power cable. To be incorporated in a WEC array system, the free-span of the cable is limited. Moreover, the cable is subject to the motion and load of the WEC, waves and currents. In this paper, the characteristics of the power cables are assessed with a numerical model applied through a parametric analysis, which varies important design parameters, such as the cable length, mass, and bending stiffness. The results of the numerical simulations are compared and discussed in terms of the forces that act on the power cables, including dynamic motion, curvature, cross sectional forces, and accumulated fatigue damage.

  • 20943.
    Yang, Shun-Han
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport, Safety. Chalmers University of Technology, Sweden.
    Hu, Zhiquang
    Newcastle University, UK.
    Biofouling on mooring lines and power cables used in wave energy converter systems - analysis of fatigue life and energy performance2017In: Applied Ocean Research, ISSN 0141-1187, E-ISSN 1879-1549, Vol. 65, p. 166-177Article in journal (Refereed)
    Abstract [en]

    This study presents an analysis of a wave energy converter (WEC) system consisting of a buoy, a mooring system, and a power cable connected to a hub. The investigated WEC system is currently under full-scale testing near Runde in Norway. The purpose of the study was to investigate the characteristics of the entire system, primarily with regard to energy performance and the fatigue life of the mooring lines and power cable, considering the effects of marine biofouling and its growth on the system’s components. By means of parametric study, the energy performance and fatigue life of the mooring lines and power cable were investigated considering two mooring configurations, three biofouling conditions, four sea states in a scatter diagram, and three wave and current directions. Hydrodynamic and structural response simulations were conducted in a coupled response analysis using the DNV-GL software SESAM. Energy performance analyses and stress-based rainflow counting fatigue calculations were performed separately using an in-house code. The results show that, for a WEC system which has been deployed for 25 years, biofouling can reduce the total power absorption by up to 10% and decrease the fatigue life of the mooring lines by approximately 20%

  • 20944.
    Yang, Shun-Han
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W.
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport, Safety. Chalmers University of Technology, Sweden.
    Parametric study of the dynamic motions and mechanical characteristics of power cables for wave energy converters2017In: Journal of marine science and technology, Vol. 23, no 1, p. 10-29Article in journal (Refereed)
    Abstract [en]

    A case study of a point-absorber wave energy converter (WEC) system is presented. The WEC system forms an array, with several WECs located around a central hub to which they are each connected by a short, free-hanging power cable. The objective of the study is to analyse the dynamic characteristics and estimate the fatigue life of the power cable which is not yet in use or available on the commercial market. Hence, a novel approach is adopted in the study considering that the power cable’s length is restricted by several factors (e.g., the clearances between the service vessel and seabed and the cable), and the cable is subject to motion and loading from the WEC and to environmental loads from waves and currents (i.e., dynamic cable). The power cable’s characteristics are assessed using a numerical model subjected to a parametric analysis, in which the environmental parameters and the cable’s design parameters are varied. The results of the numerical simulations are compared and discussed regarding the responses of the power cables, including dynamic motion, curvature, cross-sectional forces, and accumulated fatigue damage. The effects of environmental conditions on the long-term mechanical life spans of the power cables are also investigated. Important cable design parameters that result in a long power cable (fatigue) service life are identified, and the cable service life is predicted. This study contributes a methodology for the first-principle design of WEC cables that enables the prediction of cable fatigue life by considering environmental conditions and variations in cable design parameters.

  • 20945.
    Yang, Shun-Han
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport, Safety. Chalmers University of Technology, Sweden.
    Hu, Zhiqiang
    Newcastle University, UK.
    Bergdahl, Lars
    Chalmers University of Technology, Sweden.
    Duan, Fei
    Shanghai Jiao Tong University, China.
    Experimental and numerical investigation of a taut-moored wave energy converter: A validation of simulated buoy motions2018In: Journal of Engineering for the Maritime Environment (Part M), ISSN 1475-0902, E-ISSN 2041-3084, Vol. 232, no 1, p. 97-115Article in journal (Refereed)
    Abstract [en]

    This study presents an experimental and numerical investigation of a taut-moored wave energy converter system with a point-absorber type of wave energy converter. The wave energy converter system consists of a buoy, a unique three-leg two-segment mooring system with submerged floaters, and a power take-off system designed for the current experiment as a heave plate. The main objective of the study is to validate a numerical simulation model against experiments carried out in an ocean basin laboratory. Two physical models in model scales 1:20 and 1:36 were built and tested. The detailed experimental testing programme encompasses tests of mooring system stiffness, decay tests, and different sea state conditions for ocean current, regular, and irregular waves. A numerical model in the model scale 1:20 was developed to simulate coupled hydrodynamic and structural response analyses of the wave energy converter system, primarily using potential flow theory, boundary element method, finite element method, and the Morison equation. Several numerical simulations are presented for each part of the experimental testing programme. Results for the wave energy converter buoy motions under operational conditions from the experiments and the numerical simulations were compared. This study shows that the simulation model can satisfactorily predict the dynamic motion responses of the wave energy converter system at non-resonant conditions, while at resonant conditions additional calibration is needed to capture the damping present during the experiment. A discussion on simulation model calibration with regard to linear and non-linear damping highlights the challenge to estimate these damping values if measurement data are not available.

  • 20946.
    Yang, Shun-Hang
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W.
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut. Chalmers University of Technology, Sweden.
    Hu, ZhiQiang
    Shanghai Jiao Tong University, China.
    Palm, Johannes
    Chalmers University of Technology, Sweden.
    A comparison of coupled and de-coupled simulation procedures for the fatigue analysis of wave energy converter mooring lines2016In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 117, p. 332-345Article in journal (Refereed)
    Abstract [en]

    Mooring systems for floating wave energy converters (WECs) must be designed to survive the cyclical loads and motions to which they are subjected as a result of the wave load-WEC interaction and the motions of the WEC in the random elevation of the sea surface. The current study compares simulation procedures for the fatigue analysis of WEC moorings. The objective is to suggest a simulation procedure suitable for an extensive study of the behaviour of WEC systems and thus for the fatigue analysis of mooring lines. A cylindrical, floating WEC with four spread mooring lines is chosen as case study. The dynamics of the WEC system are simulated and analysed using both coupled and de-coupled models in the time-domain. Four types of simulation procedures are compared using commercial software, DNV DeepC, and an in-house solver, MooDy. A systematic fatigue response analysis based on variations of the numerical and physical parameters is conducted. The results are compared with respect to the fatigue damage calculated using the stress-based approach and the rainflow counting method. The simulation procedure using a coupled model is suggested as the preferred numerical method for capturing the interaction between the components of WEC system, which is proven to be crucial for the fatigue damage evaluation of mooring lines.

  • 20947.
    Yang, Xiong
    et al.
    KTH Royal Institute of Technology, Sweden; Zhejiang University, China .
    Lindberg, Robert
    KTH Royal Institute of Technology, Sweden.
    Margulis, Walter
    RISE - Research Institutes of Sweden, ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Fröjdh, Krister
    Proximion AB, Sweden.
    Laurell, Fredrik
    KTH Royal Institute of Technology, Sweden.
    Rapid and continuously tunable narrow linewidth fiber source based on a SOA and a linearly chirped fiber Bragg grating2019In: Conference on Lasers and Electro-Optics OSA Technical Digest (Optical Society of America, 2019), paper SM1L.5, OSA - The Optical Society , 2019, article id SM1L.5Conference paper (Refereed)
    Abstract [en]

    We demonstrate a tunable narrow-linewidth laser based on a semiconductor optical amplifier and a linearly chirped FBG. High tuning resolution and small power variation over 40 nm tuning range were achieved by optimizing the drive current.

  • 20948.
    Yang, Xuan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Berthold, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, Biobased Materials.
    Berglund, Lars
    KTH Royal Institute of Technology, Sweden.
    High-Density Molded Cellulose Fibers and Transparent Biocomposites Based on Oriented Holocellulose2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 10, p. 10310-10319Article in journal (Refereed)
    Abstract [en]

    Ecofriendly materials based on well-preserved and nanostructured wood cellulose fibers are investigated for the purpose of load-bearing applications, where optical transmittance may be advantageous. Wood fibers are subjected to mild delignification, flow orientation, and hot-pressing to form an oriented material of low porosity. The biopolymer composition of the fibers is determined. Their morphology is studied by scanning electron microscopy, cellulose orientation is quantified by X-ray diffraction, and the effect of beating is investigated. Hot-pressed networks are impregnated by a methyl methacrylate monomer and polymerized to form thermoplastic wood fiber/poly(methyl methacrylate) biocomposites. Tensile tests are performed, as well as optical transmittance measurements. Structure-property relationships are discussed. High-density molded fibers from holocellulose have mechanical properties comparable with nanocellulose materials and are recyclable. The thermoplastic matrix biocomposites showed superior mechanical properties (Young's modulus of 20 GPa and ultimate strength of 310 MPa) at a fiber volume fraction of 52%, with high optical transmittance of 90%. The study presents a scalable approach for strong, stiff, and transparent molded fibers/biocomposites.

  • 20949.
    Yang, Xuan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Berthold, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, Biobased Materials.
    Berglund, Lars A
    KTH Royal Institute of Technology, Sweden.
    Preserving Cellulose Structure: Delignified Wood Fibers for Paper Structures of High Strength and Transparency.2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 7, p. 3020-3029Article in journal (Refereed)
    Abstract [en]

    To expand the use of renewable materials, paper products with superior mechanical and optical properties are needed. Although beating, bleaching, and additives are known to improve industrially produced Kraft pulp papers, properties are limited by the quality of the fibers. While the use of nanocellulose has been shown to significantly increase paper properties, the current cost associated with their production has limited their industrial relevance. Here, using a simple mild peracetic acid (PAA) delignification process on spruce, we produce hemicellulose-rich holocellulose fibers (28.8 wt %) with high intrinsic strength (1200 MPa for fibers with microfibrillar angle smaller than 10°). We show that PAA treatment causes less cellulose/hemicellulose degradation and better preserves cellulose nanostructure in comparison to conventional Kraft pulping. High-density holocellulose papers with superior mechanical properties (Young's modulus of 18 GPa and ultimate strength of 195 MPa) are manufactured using a water-based hot-pressing process, without the use of beating or additives. We propose that the preserved hemicelluloses act as "glue" in the interfiber region, improving both mechanical and optical properties of papers. Holocellulose fibers may be affordable and applicable candidates for making special paper/composites where high mechanical performance and/or optical transmittance are of interest.

  • 20950. Yang, Yunpeng
    et al.
    Laarz, Eric
    YKI – Ytkemiska institutet.
    Forming and Drying: Chapter 32003In: Handbook of Advanced Ceramics: Materials Science, Academic Press, 2003, p. 131-185Chapter in book (Refereed)
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