Browsing by Author "Hsu, YY"

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A hierarchical proxy architecture with load-based scheduling scheme to support network mobility
(2003)
Hsu, YY
;
Tseng, CC
;
資訊工程學系
;
Department of Computer Science
A mobile router and all its attached nodes constitute a mobile network A mobile network may be deployed in a mass transportation to enable people to access the Internet when traveling. However, people in the mobile network have to share scarce wireless bandwidth, and thus tolerate unreasonable long delay if their requests were not scheduled appropriately, In this paper, we present a hierarchical-proxy architecture and a load-based scheduling scheme to enhance the performance of the mobile networks with two-tier wireless interfaces. The load-based scheduling scheme classifies Internet services into lightweight and heavyweight services according to their response data sizes and allows heavyweight services to be transferred only in the low-tier network With the load-based scheduling scheme, we can prevent heavyweight services from occupying the scarce high-tier bandwidth and hampering the transmission of other lightweight services. Simulation results show that the proposed architecture and scheduling scheme can significantly increase the completion rate and decrease the average waiting time of both lightweight and heavyweight services, and thus can serve more concurrent requests of multi-services in the mobile network.
Anisotropic impurity scattering effects on T-c and H-c2 in YBa2Cu3Ox
(1999-03-01)
Lin, JY
;
Chen, SJ
;
Chen, SY
;
Chang, CF
;
Yang, HD
We have studied the impurity effects on the superconducting transition temperature T-c and the upper critical field H-c2 in electron irradiated YBa2Cu3Oy with in-plane oxygen defects and YBa2(Cu1-xZnx)(3)O-y. It is found that the effects of the same type of defects or impurities on T-c are the same regardless of the oxygen contents of the samples. Furthermore, T-c decreases slower in irradiated YBa2Cu3Oy than in YBa2(Cu1-xZnx)(3)O-y. This may be well explained by the model that the scattering due to in-plane oxygen defects is more anisotropic than that due to Zn impurities. The different behavior of the reduced slopes (dH(c2)/dT)(Tc)/(dH(c2)/dT)(Tc0) these two types of samples can also be understood in this context. [S0163-1829(99)08309-5].
Characterization of lead-bismuth eutectic nanowires
(2005-04-01)
Kuo, CG
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Hsu, YY
;
Wu, MK
;
Chao, CG
;
材料科學與工程學系
In this work, lead-bismuth eutectic alloy nanowires were fabricated by a novel vacuum melting method and centrifugal process. An anodic aluminum oxide (AAO) template was used to produce an array of ordered, dense, and continuous Pb-Bi nanowires. Scanning electron microscopy and transmission electron microscopy investigations reveal that nanowires with a diameter of 80 nm are composed of Pb7Bi3 and Bi phases, and have a single orientation of growth. Magnetic susceptibility and hysteresis measurements have been used to characterize the superconductive and magnetic properties of the nanowires. The results show that Pb-Bi nanowires have a slightly lower superconducting transition temperature than Pb-Bi eutectic alloy bulk, and only about 1% superconductivity volume fraction in magnetic fields both perpendicular and parallel to the plate. In magnetization curves, a fairly large hysteresis is observed for both field orientations.
Design and implementation of two-tier Mobile Ad Hoc Networks with seamless roaming and load-balancing routing capability
(2004)
Hsu, YY
;
Tseng, YC
;
Tseng, CC
;
Huang, CF
;
Fan, JH
Due to its flexibility, Mobile Ad Hoc Network (MANET) has attracted a lot of attention recently. Most existing works, however, limit a MANET as a stand-alone network. In this paper, we propose a two-tier MANET by extending the connectivity of the MANET to the Internet. Some hosts in the MANET are equipped with cellular interfaces and are called gateways, which can provide Internet connections. Such extension would greatly improve the connectivity of MANET To maintain seamless connectivity, we modify the Mobile IP to make traversing private networks (i.e., NAT) of cellular networks possible. We also propose a load-balancing routing protocol to utilize the cellular interfaces of gateways, which are likely to be bottlenecks to the Internet. A prototype is implemented and performance results obtained from the testbed is reported.
Parameters study to improve sidewall roughness in Advanced Silicon Etch process
(2001)
Liu, HC
;
Lin, YH
;
Chou, BCS
;
Hsu, YY
;
Hsu, WS
In ICP-RIE process, there have been many investigations on etching rate. However, only few published reports mentioned the sidewall roughness, which is a critical issue for optical devices. Here, experimental investigations about fabrication parameters in the STS Advanced Silicon Etch (ASE) process for sidewall roughness are performed. In our experiments, the photoresist of AZ1500 is used, and several parameters in the ASE process like over time, ramping time, Ar flow rate, platen power, and etching cycle time have been systematically studied. It is found that sidewall mean roughness can be down to 9.11 nm at etching rate of 2.5 mum/min. Comparing with other published works at similar sidewall roughness (around 10 nm), our experimental data have the highest etching rate. For the same STS ICP-RIE systems, our data have smallest sidewall roughness, comparing to previous literatures.
Prime DHCP: A prime numbering address allocation mechanism for MANETs
(2005-08-01)
Hsu, YY
;
Tseng, CC
;
資訊工程學系
;
Department of Computer Science
Most address allocation schemes rely on broadcasting for address solicitation and/or duplicate address detection. In this paper, we propose a Prime DHCP scheme that can allocate addresses to the hosts of a MANET without broadcasting, over the whole MANET. Prime DHCP makes each host a DHCP proxy of the MANET and run a prime numbering address allocation Algorithm individually to compute unique addresses for address allocation. The concept of DHCP proxies and the prime numbering address allocation algorithm together eliminate the needs for broadcasting in the MANET. Performance results show that Prime DHCP can significantly reduce the signal overhead and the latency for hosts to acquire addresses.
Raman scattering studies of single-crystal La1-xSrxMnO3
(2005-06-01)
Her, JL
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Liu, HL
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Mukovskii, YM
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Lin, JY
;
Hsu, YY
We present the results of Raman scattering studies of single-crystal La1-xSrxMnO3 (x = 0.05, 0.10, 0.15, 0.20, 0.25, and 0.35) as a function of doping and in the temperature range 10-300 K. The room-temperature Raman spectrum of the x = 0.05 compound displays four phonon bands near similar to 260, 488, 612, and 674 cm(-1). With increasing Sr doping, and a corresponding structural phase transition from an orthorombic to a rhombohedral form, there is a broadening of the linewidths and a decrease in intensities of these phonon modes. 14 When the temperature is lowered, for the x = 0.05 material, two low-frequency phonons associated with the out-of-phase rotation and internal bending of MnO6 octahedra show a noticeable hardening below the canted anti-ferromagnetic transition, which is an evidence for strong spin-phonon coupling. Interestingly, this anomalous behavior disappears in the higher Sr doping level.