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Discussion on Least Squares Inverse Time Migration Method Based on Plane Wave static coding

AGRO FOOD INDUSTRY HI-TECH 2017年第3期28卷 1968-1972页

作者： Lu, Gao Yangtze Univ Coll Technol Engn Jingzhou 434020 Hubei Peoples R China

With the increasing demand for oilfield exploration technology, the least squares inverse time migration method has shown more and more important position and advantage. Therefore, in this paper, the discussion on the least squares inverse time migration method based on plane wave static coding was proposed. Firstly, the research status of the least square method at home and abroad was expounded, furthermore, the plane wave least squares migration method principle was summarized. Finally, the data analysis was conducted through the PLSR model. It's obtained that the least squares inverse time migration method based on plane wave static coding could improve the computational efficiency, improve the imaging quality and reduce the consumption of I/O.

关键词： Plane wave static coding least squares inverse time migration

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Directional modulation method to increase the capacity of confidential messages over broadcast channels

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IET COMMUNICATIONS 2020年第11期14卷 1740-1748页

作者： Yamada, Randy M. Christopher, Ryan M. Booz Allen Hamilton Arlington VA 22202 USA Virginia Polytech Inst & State Univ Bradley Dept Elect & Comp Engn Falls Church VA 22043 USA New Mexico State Univ Klipsch Sch Elect & Comp Engn Las Cruces NM 88003 USA

This study investigates information and secrecy capacity over broadcast channels through the use of directional modulation. The authors develop and demonstrate the utility of an antenna array control technique that provides communication devices with enhanced information and secrecy capacity by time-varying the array steering vectors using a novel beam control method. They show that an increase in the achievable capacity in a broadcast communication system beyond the currently-accepted Sato bound is possible by using the time domain of array steering vectors as an additional degree of freedom. Furthermore, they increase the overall secrecy capacity of the system by spatially restricting the successful reception of signals. In practical terms, this results in higher-rate, confidential messages for multiple devices for a given power constraint. They present simulation results of the array steering technique showing that direction-dependent modulation can provide broadcast channel capacity and secrecy capacity exceeding theoretical bounds for conventional, static coding techniques. They further describe an experiment and share measured results that corroborate the simulated results at the physical layer and provide insight into the proposed method.

关键词： array signal processing modulation antenna arrays channel coding channel capacity broadcast channels telecommunication security security of data telecommunication control broadcast channels secrecy capacity antenna array control array steering vectors beam control method broadcast communication system confidential messages array steering technique direction-dependent modulation broadcast channel capacity directional modulation method Sato bound time domain method degree of freedom static coding

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An Enhanced Short Text Compression Scheme for Smart Devices

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JOURNAL OF COMPUTERS 2010年第1期5卷 49-58页

作者： Islam, Md. Rafiqul Rajon, S. A. Ahsan Khulna Univ Comp Sci & Engn Discipline Khulna Bangladesh

Short Text Compression is a great concern for data engineering and management. The rapid use of small devices especially, mobile phones and wireless sensors have turned short text compression into a demand-of-the-time. In this paper, we propose an approach of compressing short English text for smart devices. The prime objective of this proposed technique is to establish a low-complexity lossless compression scheme suitable for smart devices like cellular phones and PDAs (Personal Digital Assistants) having small memory and relatively low processing speed. The main target is to compress short messages up to an optimal level, which requires optimal space, consumes less time and low overhead. Here a new static-statistical context model has been proposed to obtain the compression. We use character masking with space integration, syllable based dictionary matching and static coding in hierarchical steps to achieve low complexity lossless compression of short English text for low-powered electronic devices. We also propose an efficient probabilistic distribution based content-ranking scheme for training the statistical model. We analyze the performance of the proposed scheme as well as the other similar existing schemes with respect to compression ratio, computational complexity and compression-decompression time. The analysis shows that, the required number of operations for the proposed scheme is less than that of other existing systems. The experimental results of the implemented model give better compression for small text files using optimum resources. The obtained compression ratio indicates a satisfactory performance in terms of compression parameters including better compression ratio, lower compression and decompression time with reduced memory requirements and lower complexity. The compression time is also lower because of computational simplicity. In overall analysis, the simplicity of computational requirement encompasses the compression effective and efficien

关键词： Short Text Compression Syllable Statistical Model Text-ranking static coding Smart Devices

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Between persistently active and activity-silent frameworks: novel vistas on the cellular basis of working memory

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ANNALS OF THE NEW YORK ACADEMY OF SCIENCES 2020年第1期1464卷 64-75页

作者： Kaminski, Jan Rutishauser, Ueli Cedars Sinai Med Ctr Dept Neurosurg 127 SS San Vicente Blvd Los Angeles CA 90048 USA CALTECH Div Biol & Biol Engn Pasadena CA 91125 USA Cedars Sinai Med Ctr Dept Neurol Los Angeles CA 90048 USA Cedars Sinai Med Ctr Dept Biomed Sci Ctr Neural Sci & Med Los Angeles CA 90048 USA

Recent work has revealed important new discoveries on the cellular mechanisms of working memory (WM). These findings have motivated several seemingly conflicting theories on the mechanisms of short-term memory maintenance. Here, we summarize the key insights gained from these new experiments and critically evaluate them in light of three hypotheses: classical persistent activity, activity-silent, and dynamic coding. The experiments discussed include the first direct demonstration of persistently active neurons in the human medial temporal lobe that form static attractors with relevance to WM, single-neuron recordings in the macaque prefrontal cortex that show evidence for both persistent and more dynamic types of WM representations, and noninvasive neuroimaging in humans that argues for activity-silent representations. A key insight that emerges from these new results is that there are several neural mechanisms that support the maintenance of information in WM. Finally, based on established cognitive theories of WM, we propose a coherent model that encompasses these seemingly contradictory results. We propose that the three neuronal mechanisms of persistent activity, activity-silent, and dynamic coding map well onto the cognitive levels of information processing (within focus of attention, activated long-term memory, and central executive) that Cowan's WM model proposes.

关键词： working memory single-neuron recordings persistent activity dynamic coding static coding attractors

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Neuronal Correlates of Spatial Working Memory in the Endbrain of Crows

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CURRENT BIOLOGY 2019年第16期29卷 2616-+页

作者： Rinnert, Paul Kirschhock, Maximilian E. Nieder, Andreas Univ Tubingen Anim Physiol Inst Neurobiol Auf Der Morgenstelle 28 D-72076 Tubingen Germany

Birds are renowned for their excellent spatial cognition. Corvid songbirds, in particular, rely on explicit representation of spatial cues in memory when caching food and retrieving caches for later consumption. However, the neuronal correlates of flexible spatial memory abilities are largely unknown in birds. We therefore trained carrion crows (Corvus corone) on a spatial delayed-response task in which they had to maintain the variable location of a visual item for a few seconds in working memory. After the crows performed this task with high precision, we recorded single-cell activity from the associative end brain area Nidopallium caudolaterale (NCL) in the behaving crows. A large fraction of NCL neurons were tuned to individual preferred locations and selectively maintained the spatial location of items in working memory. A comparison of firing rates with reaction times suggested that the majority of delay-selective neurons represented stored location information rather than motor preparation. Almost 30% of all recorded neurons were tuned during both visual presentation and memory delay, and their spatial tuning was significantly correlated. The population of recorded neurons stably maintained spatial information over the course of the working memory period. Importantly, the neural responses of spatially tuned neurons were relevant for the crows' choices and allowed a statistical classifier to predict the subsequently chosen target location in free-choice trials. Our findings demonstrate the pivotal role of the avian NCL in spatial working memory that is reminiscent of the function of the convergently evolved primate prefrontal cortex in spatial working memory.

关键词： spatial working memory delayed response dynamic coding static coding NCL Nidopallium caudolaterale crow corvus corone corvid single-cell recording

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Re-Configurable Bus Encoding Scheme for Reducing Power Consumption of the Cross Coupling Capacitance for Deep Sub-Micron Instruction Bus 04

Re-Configurable Bus Encoding Scheme for Reducing Power Consu...

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Proceedings of the conference on Design, automation and test in Europe - Volume 1

作者： Siu-Kei Wong Chi-Ying Tsui

ISBN: (纸本)9780769520858

In very deep sub-micron designs, cross coupling capacitances become the dominant factor of the total bus loading and have a significant impact on the power consumption. In this paper, we propose two reconfigurable bus encoding schemes, which are based on the correlation among the bit lines, to reduce the power consumption at the cross coupling capacitances of the instruction buses. The instruction is encoded by flipping and reordering the bit lines during compilation time to reduce the total switching capacitances. A crossbar is used to map back the data to the original instruction code before sending to the instruction decoder. The reordering can be re-configured during run-time by using different configurations in the crossbar. We propose two types of re-configuration, static and dynamic. static coding uses afix flipping and re-configuring pattern after the corresponding program is compiled. Dynamic coding allows different re-configuring patterns during program execution. Experimental results show that by using the proposed schemes, significant energy reduction, 17-23%, can be achieved. Comparisons with existing bit lines reordering encoding scheme have also been made and on average more than 15% reduction can be obtained using our method.

关键词： circuit layout CAD reconfigurable architectures system buses encoding capacitance low-power electronics reconfigurable bus encoding scheme power consumption cross coupling capacitance deep sub-micron instruction bus bus loading bit line flipping bit line reordering compilation time switching capacitances crossbar instruction decoder run-time static reconfiguration dynamic reconfiguration static coding dynamic coding program execution fix flipping reconfiguring pattern

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