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871.
WangBaoping FanJiulun XieWeixin WuChengmao 《电子科学学刊(英文版)》2004,21(4):306-313
A novel filter for image restoration is proposed in this paper. The filter estimates histogram of original image via input image. It gets a membership function through the histogram, and the membership function contains a lot of information of original image. Then a weighted fuzzy mean filter is established based on this membership function; meanwhile, the filter adaptively adopts different filter scale according to the character divergence of image region and intensity of impulsive noise. Experimental result shows that new filter gives superior performance to conventional filters and currently used fuzzy filter. 相似文献
872.
Boris Kapilevich Yosef Pinhasi Ruth Arusi Michael Anisimov Danny Hardon Boris Litvak Yan Wool 《Journal of Infrared, Millimeter and Terahertz Waves》2010,31(11):1370-1381
A single-pixel imaging remote sensor operating at 330 GHz is described. It is based on a frequency modulated continuous wave
(FMCW) and aimed at detection of concealed objects for ranges up to 40 m. The system consists of 2 horn-lens antennas integrated
with a homodyne transceiver. The synthesized linear FMCW signal at X-band is multiplied by a factor of 32 to generate the
transmitted signal. An intermediate frequency (IF) signal obtained in the output port of the 2-nd harmonic mixer is employed
for image processing. Distance measurements were made by performing data acquisition unit based on LabView interface and resulting
in a range resolution about 1 cm. Examples of 2D and 3D images reconstructed with this sensor are presented. 相似文献
873.
We introduce an efficient protocol for end-to-end handoff management in heterogeneous wireless IP-based networks. The protocol
is based on the stream control transmission protocol (SCTP), and employs a soft-handoff mechanism that uses end-to-end semantics
for signaling handoffs and for transmitting control messages. The design goal of this protocol is twofold—first, to reduce
the home registration delay, and, second, to eliminate the tunnelling cost which exists in current proposals, such as Mobile
IP and its derivatives. Furthermore, we propose successive enhancements to the initial mobility management framework for achieving
better scalability. We present strong analytical and simulation-based results that show performance improvements over existing
approaches.
Antonios Argyriou is a Ph.D. candidate in the school of electrical and computer engineering, Georgia Institute of Technology. He received his
M.S. degree from the Georgia Institute of Technology in 2003, and the diploma from Democritus University of Thrace in 2001,
both in electrical and computer engineering. His research interests spawn in all aspects of computer networking while specific
interests include wireless networks and multimedia communications. He is a student member of IEEE and ACM.
Vijay Madisetti is a professor of electrical and computer engineering at the Georgia Institute of Technology. He splits his time among teaching,
research and entrepreneurship. His interests are design, prototyping, and packaging of electronic systems, virtual prototyping,
embedded software systems, and computer networks. He obtained his Ph.D. in electrical engineering and computer science from
the University of California at Berkeley. He is a member of the IEEE and the Computer Society. 相似文献
874.
Multicasting is a useful communication method in wireless mesh networks (WMNs). Many applications in WMNs require efficient
and reliable multicast communications, i.e., high delivery ratio with low overhead among a group of recipients. In spite of
its significance, little work has been done on providing such multicast service in multi-channel WMNs. Traditional multicast
protocols for wireless and multi-hop networks tend to assume that all nodes, each of which is equipped with a single interface,
collaborate on the same channel. This single-channel assumption is not always true, as WMNs often provide nodes with multiple
interfaces to enhance performance. In multi-channel and multi-interface (MCMI) WMNs, the same multicast data must be sent
multiple times by a sender node if its neighboring nodes operate on different channels. In this paper, we try to tackle the
challenging issue of how to design a multicast protocol more suitable for MCMI WMNs. Our multicast protocol builds multicast
paths while inviting multicast members, and tries to allocate the same channel to neighboring members in a bottom-up manner.
By unifying fixed channels of one-hop multicast neighbors, the proposed algorithm can improve the performance such as reducing
multicast data transmission overhead and delay, while managing a successful delivery ratio. In order to prove such expectation
on the performance, we have implemented and evaluated the proposed solution on the real testbed having the maximum 24 nodes,
each of which is equipped with two IEEE 802.11a Atheros WLAN cards. 相似文献
875.
R. Mahesh A. P. Vinod Edmund M-K. Lai Amos Omondi 《Journal of Signal Processing Systems》2011,62(2):157-171
The ability to support multiple channels of different communication standards, in the available bandwidth, is of importance
in modern software defined radio (SDR) receivers. An SDR receiver typically employs a channelizer to extract multiple narrowband
channels from the received wideband signal using digital filter banks. Since the filter bank channelizer is placed immediately
after the analog-to-digital converter (ADC), it must operate at the highest sampling rate in the digital front-end of the
receiver. Therefore, computationally efficient low complexity architectures are required for the implementation of the channelizer.
The compatibility of the filter bank with different communication standards requires dynamic reconfigurability. The design
and realization of dynamically reconfigurable, low complexity filter banks for SDR receivers is a challenging task. This paper
reviews some of the existing digital filter bank designs and investigates the potential of these filter banks for channelization
in multi-standard SDR receivers. We also review two low complexity, reconfigurable filter bank architectures for SDR channelizers
based respectively on the frequency response masking technique and a novel coefficient decimation technique, proposed by us
recently. These filter bank architectures outperform existing ones in terms of both dynamic reconfigurability and complexity. 相似文献
876.
This work is based on the observation that existing energy management techniques for mobile devices, such as Dynamic Voltage
Scaling (DVS), are non-cooperative in the sense that they reduce the energy consumption of a single device, disregarding potential
consequences for other constraints (e.g., end-to-end deadlines) and/or other devices (e.g., energy consumption on neighboring
devices). This paper argues that energy management in distributed wireless real-time systems has to be end-to-end in nature,
requiring a coordinated approach among communicating devices. A cooperative distributed energy management technique (Co-DVS)
is proposed that (1) adapts and maintains end-to-end latencies within specified timeliness requirements (deadlines) and (2)
enhances energy savings at the devices with the highest pay-off factors that represent the relative benefits or significance of conserving energy at a device. The proposed technique employs a feedback-based
approach to dynamically distribute end-to-end slack among the devices based on their pay-off factors. 相似文献
877.
As the number of cores in chip multi-processor systems increases, the contention over shared last-level cache (LLC) resources increases, thus making LLC optimization critical, especially for embedded systems with strict area/energy/power constraints. We propose cache partitioning with partial sharing (CaPPS), which reduces LLC contention using cache partitioning and improves utilization with sharing configuration. Sharing configuration enables the partitions to be privately allocated to a single core, partially shared with a subset of cores, or fully shared with all cores based on the co-executing applications’ requirements. CaPPS imposes low hardware overhead and affords an extensive design space to increase optimization potential. To facilitate fast design space exploration, we develop an analytical model to quickly estimate the miss rates of all CaPPS configurations using the applications’ isolated LLC access traces to predict runtime LLC contention. Experimental results demonstrate that the analytical model estimates cache miss rates with an average error of only 0.73 % and with an average speedup of \(3505\times \) as compared to a cycle-accurate simulator. Due to CaPPS’s extensive design space, CaPPS can reduce the average LLC miss rate by as much as 25 % as compared to baseline configurations and as much as 14–17 % as compared to prior works. 相似文献
878.
Cheon Lee Dong-Yong Kim Jae-Hong Kim Kyoung-Cheol Lee Chang-Su Hui 《Journal of Electronic Materials》2005,34(2):132-136
We have studied the use of lasers for modifying the surface properties of silicon to improve its wettability and adhesion
characteristics. Using a 4th harmonic Nd:YAG (λ = 266 nm, pulse) laser, the wettability and adhesion characteristics of the
silicon surfaces have been enhanced by laser irradiation. It was found that laser surface treatment of silicon modified the
surface energy. By the contact angle measurement, using distilled water, the wetting characteristics of silicon after the
laser irradiation show a decrease in the contact angle and a change in the surface chemical composition. In the case of the
laser-treated silicon surface, laser direct writing of copper lines has been achieved through pyrolytic decomposition of copper
formate by using a focused Ar+ laser beam (λ = 514.5 nm, continuous wave (CW)) on the silicon substrates. The deposited lines and surface chemical compositions
were measured by energy dispersive x-ray (EDX), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS),
and surface profiler (Alpha Step 500, San Jose, CA) to examine the cross section of deposited copper lines. 相似文献
879.
This article proposes a PRNN/ERLS-based predictive QoS-promoted dynamic bandwidth allocation (PQ-DBA) scheme for upstream
transmission in Ethernet passive optical network (EPON) systems. The proposed PQ-DBA scheme originally divides incoming packets
of voice, video, data service traffic into six priorities, where packets having less room before QoS requirements violation
or being in starvation situation will be dynamically promoted to high priority cycle-by-cycle. It predicts packets arriving
at prediction interval for ONUs using pipeline recurrent neural network (PRNN)/extended recursive least squares (ERLS) so
that the bandwidth allocation can be more up-to-date and then accurate. Simulation results show that the proposed PQ-DBA scheme
achieves higher system utilization and lower average voice, video, data packet delay time than the DBAM scheme [Luo and Ansari,
OSA J Opt Netw 4(9):561–572] by 4, and 21, 90, 43%, respectively, and the PQ-DBA scheme but without prediction by 2, and 26,
29, 34%, respectively. 相似文献
880.
Motion estimation is one of the critical parts in video compression standards with a high computational load. Many motion estimation algorithms have been developed to reduce the number of search points compared to a full-search algorithm without losing the quality considerably. Most of them use fixed search patterns in their first step which may suffer from trapping into local minima or searching unnecessary blocks due to inappropriate size and type of search patterns. In this paper, a new dynamic search pattern using motion vectors of spatial and temporal neighboring blocks is proposed. The motion vectors of neighboring blocks are prioritized, in order to efficiently use of halfway stop technique. The simulation results indicate that proposed algorithm is very close to the full-search algorithm in quality, compared to other rivals. Moreover, the average number of searches is often less than other algorithms. 相似文献