| 1. |
- Pecunia, Vincenzo, et al.
(författare)
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Roadmap on energy harvesting materials
- 2023
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Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.
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| 2. |
- Sidén, Johan, 1975-, et al.
(författare)
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Design of High-Directivity Wideband Microstrip Directional Coupler With Fragment-Type Structure
- 2015
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Ingår i: IEEE transactions on microwave theory and techniques. - 0018-9480 .- 1557-9670. ; 63:12, s. 3962-3970
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Tidskriftsartikel (refereegranskat)abstract
- A novel design for a microstrip wideband directional coupler is proposedby using fragment-type structures. The use of a fragment-type structuremay provide satisfactory flexibility and excellent performance. For agiven design space, a fragment-type wideband coupler can be designed byfirst gridding the space into fragment cells and then metallizing thefragment cells selected by a multi-objective optimization searchingalgorithm, such as a multi-objective evolutionary algorithm based ondecomposition combined with enhanced genetic operators. Fordemonstration, a 20-dB wideband microstrip directional coupler isdesigned and verified by test. A 45% bandwidth centered at 2 GHz hasbeen measured in terms of maximum variation of 0.5 dB in the 20-dBcoupling level. In the operation band, the designed coupler hasdirectivity above 37 dB, and a maximum directivity of 48 dB at 2 GHz. Inaddition, some technique aspects related to multi-objective optimizationsearching, such as effects of design space, control of coupling level,and efficiency consideration for optimization searching, are furtherdiscussed. Fragment-type structures may also be used to designhigh-performance wideband directional couplers of tight coupling level.
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| 3. |
- Wang, Lu, et al.
(författare)
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Design of Chipless RFID Tag by Using Miniaturized Open-Loop Resonators
- 2018
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:2, s. 618-626
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, an open-loop resonator with fragment-loading structure is used for the first time in the design of radar cross section-based chipless radio-frequency identification (RFID) tag. By optimizing the distribution of fragment patches in an open loop, a microstrip open-loop resonator can be miniaturized so that the data capacity of the chipless RFID tag designed using such a miniaturized loop resonator can be significantly increased. Moreover, the resonant frequency of the fragment-loaded resonator can be adjusted conveniently by removing or disconnecting some fragment patches, which provides great flexibility for data encoding of the chipless RFID tag. The proposed chipless RFID tag with miniaturized open-loop resonators is designed and tested and can acquire 3.56 bits per resonator and a coding density of approximately 745.1bits/λg 2. Several experimental results validate the proposed design as well as its implementation in a realistic environment.
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| 4. |
- Wang, Lu, et al.
(författare)
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High-performance tight coupling microstrip directional coupler with fragment-type compensated structure
- 2017
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Ingår i: IET Microwaves, Antennas & Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 11:7, s. 1057-1063
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a design scheme for high-performance tight coupling microstrip coupler is proposed by adding a fragment-type compensated structure between two loosely coupled lines. Owing to its flexibility and adaptability, the fragment-type compensated structure can not only provide a quarter-wavelength phase shift for coupling enhancement, but also compensate the difference in the phase velocities of the even- and odd-modes for high directivity. Design of the fragment-type compensated structure can be implemented by multi-objective optimisation searching with several design objectives characterising tight coupling couplers. A high-efficiency optimisation searching strategy by using two-dimensional median filtering operator is employed to improve the efficiency of multi-objective optimisation. For demonstration, a high-performance 3-dB tight coupling directional coupler operating at 2 GHz is designed. The measurement data demonstrates a maximum directivity of 47 dB, above 25 dB directivity in a 21.5% bandwidth, a maximum variation of 0.3 dB in the coupling level and a maximum power division ratio of 0.6 dB, which indicate the overall performance better than the previously reported 3-dB couplers. In addition, a simplified theoretical analysis of the proposed coupler and full-wave simulated results are provided for better understanding of the fragment-type compensated structure.
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| 5. |
- Wang, Xinchen, et al.
(författare)
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Design of High-Data-Density Chipless RFID Tag Embedded in QR Code
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:3, s. 2189-2198
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Tidskriftsartikel (refereegranskat)abstract
- A design scheme for embedding a chipless radio frequency identification (RFID) tag in a quick response (QR) code is proposed and demonstrated. By searching for QR modules that can be metalized to form a loop resonator in the edge area and to load the loop in the central area, the chipless RFID tag with an optimized loaded-loop resonator can be designed in the QR code. A specific loop genetic operator is proposed for optimization searching. The optimized loaded-loop resonator has a sharp dominant resonant peak at frequency as low as possible and a harmonic resonant peak at frequency as high as possible, which provides large space for data encoding of chipless RFID. By removing or demetalizing the metalized loading modules, the resonant frequency can be tuned conveniently for frequency shift keying (FSK) coding. For demonstration, the chipless RFID tag embedded in the QR code is designed and tested. It is shown that the RFID tag allows at least nine distinct resonant frequencies for simple FSK coding, which indicates a coding capacity of 3.17 bits and a normalization coding density of approximately 501.78 bits/ $\lambda _{\mathrm {g}}^{2}$ /GHz for the chipless RFID tag embedded in the QR code.
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| 6. |
- Du, Yijun, et al.
(författare)
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Design of Sharp Roll-Off Band Notch with Fragment-Type Pattern Etched on UWB Antenna
- 2018
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 17:12, s. 2404-2408
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Tidskriftsartikel (refereegranskat)abstract
- Fragment-type etch patterns are proposed and designed on ultra-wideband planar antenna to acquire sharp roll-off band notch. Multi-objective evolutionary algorithm is applied to achieve the optimization searching of the best fragment-type etch pattern by setting multiple objectives to acquire the exact notched band and challenge the roll-off criterion (ROC) of band notch. Efficiency of the design can be improved by properly presetting slits on the patch radiator. For demonstration, designs with different slit presetting are implemented and tested. With single slit preset, band notch of ROC=0.72 at the WLAN band ranging from 5.15 GHz to 5.85GHz is acquired.
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| 7. |
- Du, Yijun, et al.
(författare)
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Design of ultra-wideband antenna with high-selectivity band notches using fragment-type etch pattern
- 2020
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Ingår i: Microwave and optical technology letters (Print). - : Wiley. - 0895-2477 .- 1098-2760. ; 62:2, s. 912-918
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Tidskriftsartikel (refereegranskat)abstract
- By specifying objective functions defining the two bands to be notched with high roll-off criteria (ROCs), optimization searching for the best fragment-type etch pattern on ultra-wideband (UWB) antenna is implemented by using multi-objective optimization. The optimization with too many objective functions requires special treatment to improve the searching efficiency. In this design, two slits are preset on appropriate positions on different sides of the UWB radiator to constrain the decision space for etch pattern searching and yield two initial notched bands to speed up the optimization. For demonstration, a UWB patch antenna is designed with dual-band notches of ROC = 0.63 at WiMAX band and ROC = 0.65 at WLAN band. Both the simulation and measurement results indicate that there is significant improvement of the selectivity of the dual-band notches.
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| 8. |
- Gidlund, Mikael, et al.
(författare)
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Uplink Scheduling Algorithms for QoS Support in Broadband Wireless Access Networks
- 2009
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Ingår i: Journal of Communications. - : Academy Publisher. - 1796-2021 .- 2374-4367. ; 4:2, s. 133-142
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Tidskriftsartikel (refereegranskat)abstract
- In order to support different types of multimedia applications, the IEEE 802.16 standard defines different service classes with their associated Quality of Service (QoS) parameters. The scheduling algorithm is the crucial point in QoS provisioning over such broadband wireless access (BWA) network and it is important that the scheduling algorithm have a multi-dimensional objective of satisfying QoS requirements of the users, maximizing system utilization and ensuring fairness among users. In this article we present two different scheduling algorithms for the uplink (UL) connection. One is a combination of legacy scheduling algorithms earliest deadline first (EDF) and weighted fair queuing (WFQ). The other proposed algorithm is a cross-layer algorithm that pledges fairness among admitted connections and it also supports all service classes. The proposed scheduling algorithms are compared to several other scheduling algorithms for UL traffic under different mixes of traffic and for various characteristics of the IEEE 802.16 MAC layer such as UL burst preamble, frame length and bandwidth request mechanisms. Simulation results indicate that legacy scheduling algorithms are not suitable for the multi-class traffic in IEEE 802.16 since they do not explicitly incorporate the QoS parameters for the given standard.
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| 9. |
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| 10. |
- Jonsson, Peter, et al.
(författare)
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High-Directivity Fractal-Vee Dipoles
- 2002
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Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - : IEEE conference proceedings. - 0780373308 ; , s. 558-561
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Konferensbidrag (refereegranskat)
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