Using OFDM and space-time coding to achieve asynchronous cooperative diversity has been proposed by Mei et. al. and Shin et al, where orthogonal space-time block codes, Alamouti code in particular, were used at relay ...
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Using OFDM and space-time coding to achieve asynchronous cooperative diversity has been proposed by Mei et. al. and Shin et al, where orthogonal space-time block codes, Alamouti code in particular, were used at relay nodes. This proposed space-time coding can not achieve the multipath diversity when the channels from nodes to nodes are frequency selective fading. In this paper, we also consider asynchronous cooperative communications where the channels are assumed to be frequency-selective fading. We design high rate distributed space-frequency codes to achieve both full asynchronous cooperative diversity and multipath diversities.
A Hebbian learning algorithm based on proportion sampling is presented that can be used to implement on-chip learning for a binary spiking neural network. A correlation filter estimates when statistical independence h...
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A Hebbian learning algorithm based on proportion sampling is presented that can be used to implement on-chip learning for a binary spiking neural network. A correlation filter estimates when statistical independence has been obtained between subsequent samples. Simulation shows that the correlation filter reduces falsely learned connections in environments were inputs are randomly activated an average of 83% of the total time. A correlation filter for 255 binary samples is implemented using 21 gates and a surface area of .0008cm2 for a .5μ fabrication process. Compared to traditional neural networks, the spiking neural network learned an odor in a single epoch resulting in only a 7% error, while classical learning algorithms required multiple epochs and typically resulted in 30% error.
Recent advances in nanotechnology have opened the door to the use of hybrid devices in integrated system-on-a-chip. The Piezo Electrochemical Transducer (PECT) effect device uses nano-dimensioned graphite fibers, wher...
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Recent advances in nanotechnology have opened the door to the use of hybrid devices in integrated system-on-a-chip. The Piezo Electrochemical Transducer (PECT) effect device uses nano-dimensioned graphite fibers, where the PECT effect can be effectively used to control current and voltage levels. The PECT effect, discovered (in early 1980's) and named by co-author F. L. Vogel, uses graphite fiber intercalated with sulfuric acid (H2SO4) to shrink parallel to the graphite planes (basal plane), whereas the reverse PECT effect causes the graphite fiber to expand. The reverse PECT effect appears by reversing the direction of the electrolysis current. This paper explores the physical properties of PECT and its applications to developing novel solid-state hybrid devices, including new kinds of transducers and transistors based on graphite that will have a significant impact on future bio-inspired integrated circuits and nano-technology.
This paper presents an integrated power system for low-power wireless sensor networks with dynamic efficiency optimization technique. By adaptively resizing power transistors and adjusting switching frequency, system ...
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This paper presents an integrated power system for low-power wireless sensor networks with dynamic efficiency optimization technique. By adaptively resizing power transistors and adjusting switching frequency, system efficiency is enhanced significantly. Theoretical analysis is elaborated to support the proposed technique. A prototype integrated power system for self-powered photovoltaic wireless sensing node was designed and simulated with TSMC 0.35μm CMOS process. With a power range of 0.5μW to 10mW, power efficiency stays above 71%. Tolerance between theoretical and simulated optimal power transistor sizes is less than 6.7%, while that of optimal switching frequencies is less than 5%. The paper gives another solution to minimizing system power in the perspective of power processing. Copyright 2005 ACM.
The growing complexity of distributed systems in terms of hardware components, operating system, communication and application software and the huge amount of dependencies among them have caused an increase in demand ...
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A new point-to-point cascade bus architecture and pseudo-differential current signaling present, which is called WiseBus™. The proposed transmitter using capacitive coupling error cancellation and fast cut-off scheme ...
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ISBN:
(纸本)490078401X
A new point-to-point cascade bus architecture and pseudo-differential current signaling present, which is called WiseBus™. The proposed transmitter using capacitive coupling error cancellation and fast cut-off scheme compensates an inherent charge error and duty error of output current. The receiver makes high common noise rejection between reference and data using perfectly matched gain-enhanced regulated cascode buffer. The advantage of proposed interface is very low power consumption and low EMI using small current signal(±100μA) and small signal loop area, and it is suitable for large size LCD TV due to point-to-point cascade bus configuration.
Processing of image windows rather than complete images is useful for robots incorporating visual servoing as high image processing rates are required. Each image window is segmented, often by thresholding, to identif...
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Processing of image windows rather than complete images is useful for robots incorporating visual servoing as high image processing rates are required. Each image window is segmented, often by thresholding, to identify features of interest. To adapt to changing conditions and to achieve the thresholding of low contrast and shadowed windows, a sophisticated method for performing dynamic segmentation is required. Segmentation methods from the pattern recognition and optical character recognition fields were studied to determine their effectiveness at thresholding 32 by 32 pixel image windows of circular hole features. The segmentation technique must be capable of preserving the centroid location with sub-pixel accuracy. To this end a new morphological preprocessing method is introduced to improve the performance of most thresholding algorithms. It was found that this new preprocessing method was able to improve the centroid location error by nearly 40% when Yasuda's thresholding algorithm was used. The preprocessing algorithm in combination with Yasuda's thresholding algorithm was able to segment the holes with an average centroid location error of 0.423 pixels and a standard deviation of 0.328 pixels.
This work investigated the potential for the non-contact measurement of volumetric soil moisture profiles by detecting reflected VHF and UHF radio waves. The investigation included the development of an instrumentatio...
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This work investigated the potential for the non-contact measurement of volumetric soil moisture profiles by detecting reflected VHF and UHF radio waves. The investigation included the development of an instrumentation system to measure radio wave reflection coefficients, a calibration routine for such a system, a model for simulating electromagnetic reflections from layered dielectric media, and an algorithm devised to resolve layers of moisture from radio wave reflections of multiple frequencies. Field trials of the system were conducted in which measured reflection coefficients were compared with simulated results, and predicted moisture gradients were compared with actual moisture profiles. The model that simulated reflection coefficients in the frequency range of 80 MHz to 1 GHz was tested using hypothetical and existent moisture profiles. Results of simulated profiles indicated that reflection coefficients could be used to distinguish between volumetric surface moisture and could detect subsurface moisture to a depth of 45.7 cm. Reflection measurements made in the field trials indicated that linear correlation could be made with volumetric moisture in the top 15.2 cm. The profile restoration algorithm closely predicted simulated near-surface moisture but had a high failure rate predicting deep subsurface moisture. Results of the study indicated that reflection coefficients could be used to detect soil moisture at depth, but the restoration algorithm did not effectively resolve moisture layers.
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