| 1. |
- Wang, Yuan, et al.
(författare)
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Three Gossiping Protocols in Three-Dimensional Underwater Optical Cellular Network
- 2023
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Ingår i: 2023 Asia Communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- In this paper, three different low-complexity sector-based Gossiping routing protocols, namely Gossiping with probabilistic selection (Gossiping-PS), Gossiping with visibility priority (Gossiping-VP), and Gossiping with energy priority (Gossiping-EP), are evaluated through the three-dimensional underwater optical cellular network (UOCN). Comprehensive performance comparisons are made among the above three routing protocols in terms of the average hop, end-to-end delay, network lifetime, packet-loss rate, and energy utilization. Numerical analysis shows that Gossiping-PS significantly outperforms the other two schemes, while Gossiping-Vpand Gossiping-EP behave even worse than the standard Gossiping routing protocol under some circumstances, which is owing to the fact that the Greedy algorithm makes the best choice for the current moment instead of taking the global optimality into consideration.
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| 2. |
- Zhang, Tianyi, et al.
(författare)
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19.02Gbps/25m Underwater Wireless Optical Communication Adopting Probabilistic Constellation Shaping QAM-DMT Transmission
- 2023
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Ingår i: 2023 Asia Communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrated probabilistic constellation shaping quadrature amplitude modulation discrete multitone (PCS QAM-DMT) for 25-m underwater wireless optical communication (UWOC) system with a net data rate of 19.02Gbps. 28.1% capacity improvement is achieved in comparison with conventional bit-power loading DMT scheme. To the best of our knowledge, this is the highest net data rate ever reported for a single LD in current UWOC.
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| 3. |
- Jin, Bao, et al.
(författare)
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Phase transition structural superlubricity
- 2024
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Ingår i: Matter. - : Cell Press. - 2590-2393 .- 2590-2385.
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Tidskriftsartikel (refereegranskat)abstract
- Structural superlubricity refers to a state with almost vanishing friction and wear between crystalline surfaces in incommensurate configurations. However, thus far, this phenomenon has been observed only at solid-solid interfaces. Here, we constructed an in situ heterojunction between a crystalline boundary tribofilm and a pressure-induced solid-phase 1–dodecanol molecular layer, achieving structural superlubricity in a liquid-solid interface. This novel superlubricity state, termed phase transition structural superlubricity (PTSS), is induced by incommensurate slip at the in situ heterojunction. Atomic force microscopy experiments and molecular dynamics simulations demonstrated that the friction of in situ heterojunction exhibits a periodicity of 180°. Notably, the PTSS arises when the molecular axis of 1–dodecanol is oriented 90° to the direction of friction. These findings provide a novel design strategy for structural superlubricity and bridge the gap between liquid and solid superlubricity, shedding substantial light upon achieving structural superlubricity across a broad range of environments.
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| 4. |
- Wang, Yuan, et al.
(författare)
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Half-spectrum OFDM to quadruple the spectral efficiency of underwater wireless optical communication with digital power division multiplexing
- 2024
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Ingår i: Applied Optics. - : Optica Publishing Group. - 1559-128X .- 2155-3165. ; 63:9, s. 2352-2361
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Tidskriftsartikel (refereegranskat)abstract
- Improving the spectrum efficiency (SE) is an effective method to further enhance the data rate of bandwidthmultiplexing (NOFDM) with a compression factor of 0.5 can save half of the bandwidth without introducing any inter-carrier-interference (ICI) only if the total number of subcarriers is large enough, and we termed it as half-spectrum OFDM (HS-OFDM). To the best of our knowledge, this is the first reported work on a closed-form HS-OFDM signal in the discrete domain from the perspective of a correlation matrix. Due to the special mathematical property, no extra complex decoding algorithm is required at the HS-OFDM receiver, making it as simple as the conventional OFDM receiver. Compared with traditional OFDM, HS-OFDM can realize the same data rate, but with a larger signal-to-noise ratio (SNR) margin. To fully use the SNR resource of the communication system, we further propose a digital power division multiplexed HS-OFDM (DPDM-HS-OFDM) scheme to quadruple the SE of conventional OFDM for the bandwidth-starved UWOCs. The experimental results show that HS-OFDM can improve the receiver sensitivity by around 4 dB as opposed to conventional 4QAM-OFDM with the same data rate and SE. With the help of the DPDM-HS-OFDM scheme, the data rate of multi-user UWOC can reach up to 4.5 Gbps under the hard-decision forward error correction (HD-FEC) limit of a bit error rate (BER) of 3.8 x 10-3. Although there is some performance degradation in comparison with single-user HS-OFDM, the BER performance of multi-user DPDM-HS-OFDM is still superior to that of conventional single-user 4QAM-OFDM. Both single-user HS-OFDM and multi-user DPDM-HS-OFDM successfully achieve 2 Gbps/75 m data transmission, indicating that the DPDM-HS-OFDM scheme is of great importance in bandwidth-limited UWOC systems and has guiding significance to underwater wireless optical multiple access.
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| 5. |
- Xie, Yitong, et al.
(författare)
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Dual-polarization Multiplexing and Nonlinear Equalization Assisted in LED-based Underwater Wireless Optical Communication
- 2024
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Ingår i: 2024 Photonics and Electromagnetics Research Symposium, PIERS 2024 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc..
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Konferensbidrag (refereegranskat)abstract
- Underwater wireless communication outperforms cable-based communication with better maneuverability and simplicity of deployment, in which underwater wireless optical communication (UWOC) has attracted considerable interest due to its merits of low cost, large bandwidth, low latency, and high flexibility compared to mature acoustic communication. Furthermore, UWOC shows the prospect of enhancing the performance of current underwater wireless sensor networks (UWSNs). In this paper, dual-polarization multiplexing is employed to double the transmission capacity in the proposed LED-based UWOC system. Furthermore, Volterra series-based nonlinear equalization is utilized to mitigate the nonlinear impairment and thus further improve the system performance. The effectiveness of single-carrier nonlinear equalization is experimentally verified in the LED-based dual-polarization multiplexing UWOC system. The results show that compared with linear equalization, > 3dB signal-to-noise ratio (SNR) gain can be achieved by the nonlinear equalization in the dual-polarization UWOC system. Compared with the single polarization system, the transmission capacity approximately doubles in the dual-polarization multiplexing UWOC system, and the cross talk between x and y polarization is also analyzed.
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| 6. |
- Jiang, Bing-Xin, et al.
(författare)
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Fabrication and bonding of In bumps on Micro-LED with 8 μ m pixel pitch
- 2024
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Ingår i: ENGINEERING RESEARCH EXPRESS. - 2631-8695. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Indium (In) is currently used to fabricate metal bumps on micro-light-emitting diode (Micro-LED) chips due to its excellent physical properties. However, as Micro-LED pixel size and pitch decrease, achieving high-quality In bumps on densely packed Micro-LED chips often presents more challenges. This paper describes the process of fabricating In bumps on micro-LEDs using thermal evaporation, highlighting an issue where In tends to grow laterally within the photoresist pattern, ultimately blocking the pattern and resulting in undersized and poorly dense In bumps on the Micro-LED chip. To address this issue, we conducted numerous experiments to study the height variation of In bumps within a range of photoresist aperture sizes (3 mu m -7 mu m) under two different resist thickness conditions (3.8 mu m and 4.8 mu m). The results showed that the resist thickness had a certain effect on the height of In bumps on the Micro-LED chip electrodes. Moreover, we found that, with the photoresist pattern size increasing under constant resist thickness conditions, the height and quality of the bumps significantly improved. Based on this finding, we rationalized the adjustment of the photoresist pattern size within a limited emission platform range to compensate for the height difference of In bumps caused by different resist thicknesses between the cathode and anode regions. Consequently, well-shaped and dense In bumps with a maximum height of up to 4.4 mu m were fabricated on 8 mu m pitch Micro-LED chips. Afterwards, we bonded the Micro-LED chip with indium bumps to the CMOS chip, and we found that we could successfully control the CMOS chip to drive the Micro-LED chip to display specific characters through the Flexible Printed Circuit (FPC). This work is of significant importance for the fabrication of In bumps on Micro-LED chips with pitches below 10 mu m and subsequent bonding processes.
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| 7. |
- He, W., et al.
(författare)
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Deep learning-assisted flexible piezoresistive sensor with liquid-phase reduced metal electrodes for fitness movement recognition and correction
- 2024
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 495
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Tidskriftsartikel (refereegranskat)abstract
- Flexibility and wearability in electronic devices gain prominence with the rise of national fitness campaigns. Among them, piezoresistive sensors stand out for their ability to accurately monitor health signals due to their high sensitivity. However, conventional metal nanoparticle ink electrodes face issues like peeling, chemical instability, and substrate limitations. This study introduces a novel method for fabricating high-performance flexible piezoresistive sensors using liquid-phase reduced metal electrodes. Integration of porous polydimethylsiloxane (PDMS) substrates with highly conductive interdigital silver electrodes (1.6 × 10−6 Ω·m) addresses conventional electrode shortcomings, offering permeability, flexibility, and outstanding conductivity. Incorporation of a graphene (GR)/carbon nanotube (CNT)/Ecoflex composite enhances sensor piezoresistive sensing capabilities, with features including high sensitivity (3.57 KPa−1), rapid response time (58 ms/72 ms), and excellent cycle stability (>10000 cycles). The sensor finds utility in various applications, including human physiological signal monitoring, pressure array recognition, and handwriting recognition. Additionally, with deep learning techniques, the system achieves accurate recognition (99.25 %) and correction (98.75 %) of diverse fitness movements, aiming to promote safer exercise practices, enhance training efficiency, and advance intelligent wearable fitness devices.
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| 8. |
- Kristan, Matej, et al.
(författare)
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The Visual Object Tracking VOT2015 challenge results
- 2015
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Ingår i: Proceedings 2015 IEEE International Conference on Computer Vision Workshops ICCVW 2015. - : IEEE. - 9780769557205 ; , s. 564-586
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge 2015, VOT2015, aims at comparing short-term single-object visual trackers that do not apply pre-learned models of object appearance. Results of 62 trackers are presented. The number of tested trackers makes VOT 2015 the largest benchmark on short-term tracking to date. For each participating tracker, a short description is provided in the appendix. Features of the VOT2015 challenge that go beyond its VOT2014 predecessor are: (i) a new VOT2015 dataset twice as large as in VOT2014 with full annotation of targets by rotated bounding boxes and per-frame attribute, (ii) extensions of the VOT2014 evaluation methodology by introduction of a new performance measure. The dataset, the evaluation kit as well as the results are publicly available at the challenge website(1).
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| 9. |
- Sun, Huiliang, et al.
(författare)
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Reducing energy loss via tuning energy levels of polymer acceptors for efficient all-polymer solar cells
- 2020
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Ingår i: Science China Chemistry. - : Springer Science and Business Media LLC. - 1869-1870 .- 1674-7291. ; 63:12, s. 1785-1792
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Tidskriftsartikel (refereegranskat)abstract
- The open-circuit voltage (Voc) of all-polymer solar cells (all-PSCs) is typically lower than 0.9 V even for the most efficient ones. Large energy loss is the main reason for limiting Voc and efficiency of all-PSCs. Herein, through materials design using electron deficient building blocks based on bithiophene imides, the lowest unoccupied molecular orbital (LUMO) energy levels of polymer acceptors can be effectively tuned, which resulted in a reduced energy loss induced by charge generation and recombination loss due to the suppressed charge-transfer (CT) state absorption. Despite a negligible driving force, all-PSC based on the polymer donor and acceptor combination with well-aligned energy levels exhibited efficient charge transfer and achieved an external quantum efficiency over 10% while maintaining a large Voc of 1.02 V, leading to a 9.21% efficiency. Through various spectroscopy approaches, this work sheds light on the mechanism of energy loss in all-PSCs, which paves an avenue to achieving efficient all-PSCs with large Voc and drives the further development of all-PSCs.
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| 10. |
- Tian, Jiahan, et al.
(författare)
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Wide-field-of-view auto-coupling optical antenna system for high-speed bidirectional optical wireless communications in C band
- 2023
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Ingår i: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 31:20, s. 33435-33448
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Tidskriftsartikel (refereegranskat)abstract
- Due to a great many superior features of infrared light communication (ILC), like high capacity and strong privacy, ILC is considered a potential candidate for serving the high demands of beyond fifth-generation/sixth-generation (B5G/6 G) communication systems. However, the terminal's limited field-of-view (FOV) induces great difficulty in establishing line-of-sight (LoS) link between the transceiver and the terminal. In this paper, we propose a wide-FOV auto-coupling optical antenna system that utilizes a wide-FOV telecentric lens to collect incident infrared beams and automatically couple them into a specific single-mode-fiber (SMF) channel of fiber array and optical switch. The performance of this optical antenna system is assessed through simulation and manual alignment operation, and validated by automatic alignment results. A coupling loss of less than 10.6 dB within a FOV of 100(degrees )for both downstream and upstream beams in C band is demonstrated by the designed system. Furthermore, we establish a bidirectional optical wireless communications (OWC) system employing this antenna and a fiber-type modulating retro-reflector (MRR) system in the terminal. Both 10-Gbps on-off keying (OOK) downstream and upstream transmissions are successfully realized with the FOV of up to 100(degrees) in C band where the measured bit-error-rate (BER) is lower than 3.8 x 10-3. To the best of our knowledge, this is a brand-new auto-coupling optical antenna system with the largest FOV in ILC automatic alignment works in terminals that have ever been reported.
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