| 1. |
- You, Xiaohu, et al.
(författare)
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Towards 6G wireless communication networks: vision, enabling technologies, and new paradigm shifts
- 2021
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Ingår i: Science China Information Sciences. - : Science Press. - 1674-733X .- 1869-1919. ; 64:1
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Forskningsöversikt (refereegranskat)abstract
- The fifth generation (5G) wireless communication networks are being deployed worldwide from 2020 and more capabilities are in the process of being standardized, such as mass connectivity, ultra-reliability, and guaranteed low latency. However, 5G will not meet all requirements of the future in 2030 and beyond, and sixth generation (6G) wireless communication networks are expected to provide global coverage, enhanced spectral/energy/cost efficiency, better intelligence level and security, etc. To meet these requirements, 6G networks will rely on new enabling technologies, i.e., air interface and transmission technologies and novel network architecture, such as waveform design, multiple access, channel coding schemes, multi-antenna technologies, network slicing, cell-free architecture, and cloud/fog/edge computing. Our vision on 6G is that it will have four new paradigm shifts. First, to satisfy the requirement of global coverage, 6G will not be limited to terrestrial communication networks, which will need to be complemented with non-terrestrial networks such as satellite and unmanned aerial vehicle (UAV) communication networks, thus achieving a space-air-ground-sea integrated communication network. Second, all spectra will be fully explored to further increase data rates and connection density, including the sub-6 GHz, millimeter wave (mmWave), terahertz (THz), and optical frequency bands. Third, facing the big datasets generated by the use of extremely heterogeneous networks, diverse communication scenarios, large numbers of antennas, wide bandwidths, and new service requirements, 6G networks will enable a new range of smart applications with the aid of artificial intelligence (AI) and big data technologies. Fourth, network security will have to be strengthened when developing 6G networks. This article provides a comprehensive survey of recent advances and future trends in these four aspects. Clearly, 6G with additional technical requirements beyond those of 5G will enable faster and further communications to the extent that the boundary between physical and cyber worlds disappears.
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| 2. |
- Chen, Xin, et al.
(författare)
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Reinforcement learning for distributed hybrid flowshop scheduling problem with variable task splitting towards mass personalized manufacturing
- 2024
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Ingår i: Journal of manufacturing systems. - : Elsevier BV. - 0278-6125 .- 1878-6642. ; 76, s. 188-206
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Tidskriftsartikel (refereegranskat)abstract
- Mass personalization manufacturing (MPM), an emerging production pattern, aims to improve enterprise profit in modern industries. However, the processing of heterogeneous orders from the consumers complicates such production scheduling problem. In addition, different scale tasks should adopt different splitting strategies in practical manufacturing, which makes the task splitting method more worthy of investigation. Towards MPM, this paper presents a distributed hybrid flowshop scheduling problem with variable task splitting (DHFSP-VTS) to minimize the makespan and total energy consumption simultaneously. Meanwhile, the VTS allows the tasks to be split into different sublots so they can save setup and transfer time. To solve these problems, we present an order modularization processing method that can categorize multiple types of orders into specific generation tasks, and a highly effective reinforcement learning-multiple objective evolutionary algorithm based on decomposition (RLMOEA/D) is designed. In RL-MOEA/D, there are three features: (1) three initial rules are used for initialization based on the current splitting scheme that can increase the diversity of solutions; (2) the reinforcement learning agent uses the Q-learning mechanism to dynamically select the scheme of task splitting as action; (3) a neighborhood search strategy improves the exploitation ability and expand the solution space. To verify the effectiveness of RL-MOEA/D, the MOEA/Ds based on four splitting schemes and four RL combined meta-heuristics are compared on 18 instances. The results show that RL-MOEA/D can obtain the best optimization and stability of all the other comparison algorithms. Therefore, it's a new technique to solve DHFSP with large-scale tasks, especially for the problem of MPM.
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| 3. |
- Wang, Xiaolei, et al.
(författare)
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Physically Based Evaluation of Effect of Buried Oxide on Surface Roughness Scattering Limited Hole Mobility in Ultrathin GeOI MOSFETs
- 2017
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9383 .- 1557-9646. ; 64:6, s. 2611-2616
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a numerical simulation study investigating the effect of buried oxide on surface roughness scattering limited hole mobility (mu(SR)) in ultrathin germanium-on-insulator (GeOI) MOSFETs, for the first time. The simulation considers wave function penetration at channel/oxide interface and nonlinear dependence of scattering matrix element on surface fluctuation. Three types of buried oxide materials are compared (GeO2, SiO2, and Si3N4). The mu(SR) increases in the order of SiO2 < GeO2 < Si3N4. This dependence of mu(SR) on buried oxide material is due to surface fluctuation scattering from backside Ge/buried oxide interface. Our simulation results show that Si3N4 and GeO2 are beneficial as buried oxide for mobility enhancement in GeOI MOSFETs, compared with conventional SiO2 as buried oxide. Our findings provide an insight into further improving mobility characteristic.
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| 4. |
- 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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| 5. |
- Luo, Jun, et al.
(författare)
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Effects of carbon pre-silicidation implant into Si substrate on NiSi
- 2014
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 120, s. 178-181
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the effects of carbon pre-silicidation implant into Si(1 0 0) substrate on NiSi were investigated. NiSi films with carbon pre-silicidation implant to different doses were characterized by means of sheet resistance measurements, X-ray diffraction, scanning electron microscopy (SEM), planar view transmission electron microscopy (TEM) and second ion mass spectroscopy (SIMS). The presence of C is found to indeed significantly improve the thermal stability of NiSi as well as tends to change the preferred orientations of polycrystalline NiSi. The homogeneously distributed C at NiSi grain boundaries and C peak at NiSi/Si interface is ascribed to the improved thermal stability of NiSi. More importantly, the dose of carbon pre-silicidation implant also plays a key role in the formation of NiSi, which is suggested not to exceed a critical value about 5 x 10(15) cm(-2) in practical application in accordance with the results achieved in this work. (C) 2013 Elsevier B.V. All rights reserved.
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| 6. |
- Hu, Enyi, et al.
(författare)
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Junction and energy band on novel semiconductor-based fuel cells
- 2021
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Ingår i: iScience. - : Elsevier BV. - 2589-0042. ; 24:3
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Forskningsöversikt (refereegranskat)abstract
- Fuel cells are highly efficient and green power sources. The typical membrane electrode assembly is necessary for common electrochemical devices. Recent research and development in solid oxide fuel cells have opened up many new opportunities based on the semiconductor or its heterostructure materials. Semiconductor-based fuel cells (SBFCs) realize the fuel cell functionality in a much more straightforward way. This work aims to discuss new strategies and scientific principles of SBFCs by reviewing various novel junction types/interfaces, i.e., bulk and planar p-n junction, Schottky junction, and n-i type interface contact. New designing methodologies of SBFCs from energy band/alignment and built-in electric field (BIEF), which block the internal electronic transport while assisting interfacial superionic transport and subsequently enhance device performance, are comprehensively reviewed. This work highlights the recent advances of SBFCs and provides new methodology and understanding with significant importance for both fundamental and applied R&D on new-generation fuel cell materials and technologies.
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| 7. |
- Liu, Jun, et al.
(författare)
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Resource utilization of municipal solid waste incineration fly ash - cement and alkali-activated cementitious materials: A review
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 852
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Forskningsöversikt (refereegranskat)abstract
- The increase in municipal solid waste (MSW) production has led to an increase in MSW incineration fly ash (MSWIFA) production. MSWIFA contains toxic and harmful substances such as heavy metals and dioxins, which can cause harm to the environment if not treated properly. Only a few MSWIFAs will be landfilled directly, and the rest will need to be treated by other methods. The treatment of MSWIFA can be divided into three types: separation, stabilization/solidification (S/S), and thermal treatment, which are either not fully developed or too costly. Resource utilization is a sustainable means of treating MSWIFA. MSWIFA is used in the production of cement and alkali-activated cementitious materials as a means of resource utilization with significant advantages. This can alleviate the consumption of nature and reduce greenhouse gas emissions in conventional cement production. Compared with MSWIFA cement, MSWIFA alkali-activated cementitious material can be achieved with almost no consumption of natural resources, which is worthy of further research to realize the large-scale application of MSWIFA. At the end of the paper, the perspective of separation of dioxins from MSWIFA, co-processing of MSWI ash, and production of “MSWIFA green materials” is presented.
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| 8. |
- Guo, Shaopeng, et al.
(författare)
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Techno-economic assessment of mobilized thermal energy storage for distributed users : A case study in China
- 2017
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Ingår i: Applied Energy. - : ELSEVIER SCI LTD. - 0306-2619 .- 1872-9118. ; 194, s. 481-486
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Tidskriftsartikel (refereegranskat)abstract
- The mobilized thermal energy storage (M-TES) system is a promising alternative to conventional heating systems to meet the heat demand for distributed users. This paper provided a techno-economic assessment of the M-TES system based on a case study in China. According to the analysis of the design specifications of the heating system, the suitability of matching the M-TES with existing heating systems was analyzed. The results show that the M-TES is appropriate for use with heating systems with a fan-coil unit and under-floor pipe. Containers and operating strategies for the M-TES with different transportation schemes were also designed. The maximum allowed load of the M-TES container is 39 t according to the discussion of transportation regulations on the road. The cost and income of the M-TES in the study case were estimated, and the net present value (NPV) and payback period (PBP) were also calculated. The best operating strategy is the use of 2 containers and 4 cycles of container transportation per day, with a PBP of approximately 10 years. The M-TES is applicable for middle and small-scale heat users in China.
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| 9. |
- Lu, Yuzheng, et al.
(författare)
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Progress in Electrolyte-Free Fuel Cells
- 2016
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Ingår i: FRONTIERS IN ENERGY RESEARCH. - : FRONTIERS MEDIA SA. - 2296-598X. ; 4
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Forskningsöversikt (refereegranskat)abstract
- Solid oxide fuel cell (SOFC) represents a clean electrochemical energy conversion technology with characteristics of high conversion efficiency and low emissions. It is one of the most important new energy technologies in the future. However, the manufacture of SOFCs based on the structure of anode/electrolyte/cathode is complicated and time-consuming. Thus, the cost for the entire fabrication and technology is too high to be affordable, and challenges still hinder commercialization. Recently, a novel type of electrolyte-free fuel cell (EFFC) with single component was invented, which could be the potential candidate for the next generation of advanced fuel cells. This paper briefly introduces the EFFC, working principle, performance, and advantages with updated research progress. A number of key R&D issues about EFFCs have been addressed, and future opportunities and challenges are discussed.
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