Browsing by Author "Wang, Da-Wei"

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Exploiting spectral reuse in resource allocation, scheduling, and routing for IEEE 802.16 mesh networks
(2007)
Chen, Lien-Wu
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Tseng, Yu-Chee
;
Wang, Da-Wei
;
Wu, Jan-Jan
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資訊工程學系
The IEEE 802.16 standard for wireless metropolitan area networks (WMAN) has been created to meet the need of wide-range broadband wireless access at low cost. The objective of this paper is to study how to exploit spectral reuse in an IEEE 802.16 mesh network through timeslot allocation, bandwidth adaptation, hierarchical scheduling, and routing. To the best of our knowledge, this is the first work which formally quantifies spectral reuse in IEEE 802.16 mesh networks and which exploits spectral efficiency under an integrated framework. Simulation results show that the proposed spectral reuse scheduling and load-aware routing significantly enhance the network throughput performance in IEEE 802.16 mesh networks.
Exploiting Spectral Reuse in Routing, Resource Allocation, and Scheduling for IEEE 802.16 Mesh Networks
(2009-01-01)
Chen, Lien-Wu
;
Tseng, Yu-Chee
;
Wang, You-Chiun
;
Wang, Da-Wei
;
Wu, Jan-Jan
The IEEE 802.16 standard for wireless metropolitan area networks (WMANs) is defined to meet the need for wide-range broadband wireless access at low cost. The objective of this paper is to study how to exploit spectral reuse in resource allocation in an IEEE 802.16 mesh network, which includes routing tree construction (RTC), bandwidth allocation, time-slot assignment, and bandwidth guarantee of real-time flows. The proposed spectral reuse framework covers bandwidth allocation at the application layer, RTC and resource sharing at the medium access control: (MAC) layer, and channel reuse at the physical layer. To the best of our knowledge, this is the first paper that formally quantifies spectral reuse in IEEE 802.16 mesh networks and exploits spectral efficiency under an integrated framework. Simulation results show that the proposed schemes significantly improve the throughput of IEEE 802.16 mesh networks.
N,P co-coordinated Fe species embedded in carbon hollow spheres for oxygen electrocatalysis
(2019-06-28)
Zhu, Xiaofeng
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Tan, Xin
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Wu, Kuang-Hsu
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Chiang, Chao-Lung
;
Lin, Yu-Chang
The increasing interest in fuel cell technology and metal-air batteries has led to the need for stable and effective catalyst materials to replace noble metal (such as Pt) based benchmarks for the oxygen reduction reaction (ORR). In this study, carbon hollow spheres with highly dispersed nitrogen and phosphorus co-coordinated iron atoms (FeNPC) on their surface have been successfully fabricated, exhibiting exceptional ORR activity in both alkaline and acidic solutions. Specifically, the obtained FeNPC catalyst is capable of catalyzing the ORR with an onset potential of 1.03 V and a half-wave potential of 0.88 V (both vs. the reversible hydrogen electrode) in alkaline solution, outperforming the commercial Pt/C catalyst under identical conditions. Experimental results and theoretical simulations reveal that the quasi-octahedral O-2-FeNxPy species are the active sites of the FeNPC composite. These species modify the electronic configuration of Fe centers and weaken the adsorption of the OH* intermediate, thereby promoting the ORR process. Additionally, the FeNPC catalyst also displays a catalytic activity towards the anodic oxygen evolution reaction (OER), making it an active air electrode catalyst in rechargeable Zn-air batteries with a high peak power density of 233.2 mW cm(-2) and an excellent cycling stability at 3 mA cm(-2) for over 15 h.
Stepped changes of monovalent ligand-binding force during ligand-induced clustering of integrin alpha(IIB)beta(3)
(2006-09-01)
Hsieh, Chia-Fen
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Chang, Bo-Jui
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Pai, Chyi-Huey
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Chen, Hsuan-Yi
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Tsai, Jin-Wu
Recent evidence demonstrated that conformational changes of the integrin during receptor activation affected its binding to extracellular matrix; however, experimental assessment of ligand-receptor binding following the initial molecular interaction has rarely been carried out at a single-molecule resolution. In the present study, laser tweezers were used to measure the binding force exerted by a live Chinese hamster ovary cell that expressed integrin alpha(IIb)beta(3) (CHO alpha(IIb)beta(3)), to the bead carrier coated with the snake venom rhodostomin that served as an activated ligand for integrin alpha(IIb)beta(3). A progressive increase of total binding force over time was noticed when the bead interacted with the CHO alpha(IIb)beta(3) cell; such an increase was due mainly to the recruitment of more integrin molecules to the bead-cell interface. When the binding strength exerted by a single ligand-receptor pair was derived from the "polyvalent" measurements, surprisingly, a stepped decrease of the "monovalent binding force" was noted (from 4.15 to 2.54 piconewtons (pN)); such decrease appeared to occur during the ligand-induced integrin clustering process. On the other hand, the mutant rhodostomin defective in clustering integrins exhibited only one (1.81 pN) unit binding strength.