| 1. |
- Chen, Hong, et al.
(författare)
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A statistical MAC protocol for heterogeneous-traffic human body communication
- 2013
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Konferensbidrag (refereegranskat)abstract
- In wireless body sensor networks (WBSN) and wireless body area networks (WBAN), sensor nodes have different bandwidth requirements, therefore, heterogeneous traffic is created. In this paper, we propose a statistical medium access control (MAC) protocol with periodic synchronization for use in heterogeneous traffic networks based on human body communication (HBC). The MAC protocol is designated to ensure energy efficiency by means of flexible time slot allocation and a statistical frame. The statistical frame is intended to increase the sleep time and keep low duty cycles in each beacon period. The MAC protocol was fully implemented on our HBC platform. The experimental results proved that the proposed MAC protocol is compact and energy-efficient.
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| 2. |
- Chen, Yuanfang, et al.
(författare)
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The scheme of mitigating the asymmetric links problem in wireless sensor networks
- 2010
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the radio irregularity (RI) phenomenon and its impact on communication performance in wireless sensor networks (WSNs). Based on the theoretical analysis, we find that the RI phenomenon induces the asymmetric links problem. According to this discovery, we propose a novel HCT (Hop-count Correction Tree) scheme to handle this problem. HCT utilizes graph theoretical method to get a search tree and correct the hop count error that appears in the adjacent nodes. Practical results obtained from testbed experiments demonstrate that this solution can greatly improve localization accuracy in the presence of RI
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| 3. |
- Lei, Ying, et al.
(författare)
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Microwave synthesis and enhancement of thermoelectric figure of merit in half-Heusler TiNiSbxSn1-x
- 2017
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Ingår i: Ceramics International. - : Elsevier Ltd. - 0272-8842 .- 1873-3956. ; 43:12, s. 9343-9347
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Tidskriftsartikel (refereegranskat)abstract
- The preparation of half-Heusler thermoelectric bulk is complex and time-consuming. In the present work, Sb doped TiNiSbxSn1-x bulks (x=0.01, 0.02, 0.03 and 0.04) were prepared via cold press forming, microwave synthesis and sintering in vacuumed sealed quartz in a few minutes. The microstructures of samples were characterized by using X-ray diffractometer (XRD) and scanning electron microscopy (SEM) techniques. The thermoelectric properties i.e. Seebeck coefficient (S), electrical resistivity (ρ) and thermal conductivity (κ) were measured on Seebeck coefficient/resistance analysis system (S/RAs) and laser flash thermal analyzer (LFT). The results show that high purity single phase was obtained after microwave sintering. The point defects came from Sb doping and the in-suit nanostructures attributed to microwave sintering process were found to lead to special microstructure. The variation trends of S, ρ, κ with temperature were analyzed. The influences of Sb doping to electrical and thermal properties were discussed. The electrical resistivity was decreased by ~84% at the cost of decreasing the Seebeck coefficient by ~25-30%. The maximum power factor of 2560 μWm-1K-2 was achieved at 673K. The lattice and total thermal conductivities are merely 1.1-1.3 and 3.8-4.0 Wm-1K-1 respectively. The thermoelectric figure of merit for TiNiSb0.03Sn0.97 was enhanced from 0.30 (773K) to 0.44 (673K and 723K) when compared to that of non-doped TiNiSn. © 2017 Elsevier Ltd and Techna Group S.r.l.
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| 4. |
- Lei, Ying, et al.
(författare)
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Microwave synthesis, microstructure, and thermoelectric properties of Zr substituted ZrxTi1-xNiSn half-Heusler bulks
- 2017
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Ingår i: Materials letters (General ed.). - : ELSEVIER SCIENCE BV. - 0167-577X .- 1873-4979. ; 201, s. 189-193
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Tidskriftsartikel (refereegranskat)abstract
- The half-Fleusler thermoelectric bulks ZrxTi1-xNiSn (x = 0.1, 0.2, 0.3, 0.4) were rapidly prepared by microwave heating. The phase composition and microstructure were characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The electrical and thermal properties were measured by Seebeck coefficient/resistance analysis system (S/RAs) and laser flash thermal analyzer (LFT). The point defects came from Zr-substitution and the in-situ nanostructure attributed to microwave sintering were found to lead to special microstructure and excellent thermal performance. The grain size of Zr0.3Ti0.7NiSn is similar to 10 mu m. The in-situ nanoscale pores and inclusions are about 300-500 nm. The highest ZT 0.60 for Zr0.3Ti0.7NiSn was achieved at 673 K.
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| 5. |
- Li, Cheng-Wang, et al.
(författare)
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Comparison of mechanical properties of various joining processes of aluminum-titanium light alloy
- 2023
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Ingår i: Suxing Gongcheng Xuebao/Journal of Plasticity Engineering. - : Beijing Res. Inst. of Mechanical and Elec. Technology. - 1007-2012. ; 30:8, s. 138-145
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Tidskriftsartikel (refereegranskat)abstract
- 5A06 aluminum alloy and TA1 titanium alloy were selected for the connection tests of flow drill screw, ultrasonic clinch and ultrasonic self-piercing riveting. The influence of plate overlap methods on mechanical properties of each group of joints was studied by static tensile tests. The results show that the mechanical properties of the flow drill screw joints and the ultrasonic self-piercing riveted joints are significantly improved when the soft plate is on top during the riveting process. The plate overlap method has little effect on the ultrasonic clinch joint. Flow drill screw joints have the best cushioning and shock absorption performance, but the stability is poor, and it is more limited when applied to body structures. Ultrasonic clinch joints have low cost and simple process, but poor shear resistance and are not suitable for body structures subjected to high stress. Compared with the other two connection methods, the ultrasonic self-piercing riveted connection has the best stability, the best tensile resistance and shear stiffness, and is suitable for much of the structure in lightweight field of automobile body. © 2023 Beijing Res. Inst. of Mechanical and Elec. Technology. All rights reserved.
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| 6. |
- Llewellyn, Tim, et al.
(författare)
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BONSEYES : Platform for Open Development of Systems of Artificial Intelligence
- 2017
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Konferensbidrag (refereegranskat)abstract
- The Bonseyes EU H2020 collaborative project aims to develop a platform consisting of a Data Marketplace, a Deep Learning Toolbox, and Developer Reference Platforms for organizations wanting to adopt Artificial Intelligence. The project will be focused on using artificial intelligence in low power Internet of Things (IoT) devices ("edge computing"), embedded computing systems, and data center servers ("cloud computing"). It will bring about orders of magnitude improvements in efficiency, performance, reliability, security, and productivity in the design and programming of systems of artificial intelligence that incorporate Smart Cyber-Physical Systems (CPS). In addition, it will solve a causality problem for organizations who lack access to Data and Models. Its open software architecture will facilitate adoption of the whole concept on a wider scale. To evaluate the effectiveness, technical feasibility, and to quantify the real-world improvements in efficiency, security, performance, effort and cost of adding AI to products and services using the Bonseyes platform, four complementary demonstrators will be built. Bonseyes platform capabilities are aimed at being aligned with the European FI-PPP activities and take advantage of its flagship project FIWARE. This paper provides a description of the project motivation, goals and preliminary work.
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| 7. |
- Yuan, Z., et al.
(författare)
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Analysis on capacity and delay for redundant multiple source routing in mobile ad hoc networks
- 2010
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Konferensbidrag (refereegranskat)abstract
- We consider the realtime services over on-demand routing protocols in ad hoc networks, where infrastructure does not exist and the network topology is highly dynamic and time-varying due to node mobilities. To reduce the end-to-end delay, we have proposed two efficient routing protocols: MSR (Multipath Source Routing) and RSR (Redundant Source Routing) in our previous work. Simulations have shown the good performance for the realtime services. Moreover, we also propose a new on-demand routing protocol RMSR (Redundant Multipath Source Routing) and show the performance of RMSR, which is an extension of MSR and RSR. The performance of the network using the RMSR algorithm in terms of network capacity and end-to-end queuing delay is analyzed by computing the number of active links. Compared with DSR, we can figure out the network capacity which is not increased by redundant packets and improve network delay from O(N) to O(log N) (where N is the number of the nodes).
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