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Cylindrical waveguide loaded with metadielectric structure is investigated to convert symmetric model into higher-order cylindrical waveguide mode. With the angular periodic dielectric grating coated with dielectric in the cylindrical waveguide, the TE04 mode can be converted to a ultra-high-order TE20,15 mode. Simulation results presented here verify the feasibility of such high-order mode converter...
Cloud Storage is a new kind of network storage technology. It is developed from Cloud Computing, which has been envisioned as the next-generation architecture of IT enterprise. Cloud Storage is very popular for its quick, cheap and convenient services. However, it also brings new and challenging security problems towards users' outsourced data. One major problem is to verify the integrity of data...
Modes in cylindrical waveguides with periodic subwavelength metal grating loaded on the inner surface are analyzed by both theory and simulation. Coupling between spoof surface plasmon mode and traditional waveguide mode provides a robust way to build TM02 single mode operation. Furthermore, a new approach to realize the well-integrated and reciprocal mode conversion between TM01 mode and TM02 mode...
The use of cloud storage services has increased rapidly in many organizations. However, the security of data stored in the cloud still remains major concerns. Due to risks of service availability failure and the possibility of malicious insiders in the single cloud, researches about "multi-clouds" have emerged recently. Recent researches that are related to multi-clouds have some limitations...
Graph pattern matching is a hot spot in the big data era, which is to find answer graphs matching a given query graph in a data graph of graph databases. "Matching" means two graphs satisfy some relation, such as isomorphism, simulation, bisimulation, etc. Since there are seldom algorithms for the subgraph bisimulation, our work commits to solve the graph pattern matching problem involving...
By moving data storage and processing from lightweight mobile devices to powerful and centralized computing platforms located in clouds, Mobile Cloud Computing (MCC) can greatly enhance the capability of mobile devices. However, when data owners outsource sensitive data to mobile cloud for sharing, the data is outside of their trusted domain and can potentially be granted to untrusted parties which...
A new hyperbolic gradient-index metalens is demonstrated at terahertz (THz) frequency, which can realize enhanced Fourier transform with extended spatial frequency bandwidth. The bandwidth can be extended to 2.5k0 (k0 is the wave-vector in air), which is 2 to 3 times of conventional lens. Furthermore, the working distance can be larger than one wavelength, and the input and output surfaces are flat,...
Caching is an effective optimization in search engine. The data selection policy plays a key role in caching, which places the data to be cached in memory. However, the current data selection policies are not suitable to the hybrid storage architecture with solid state disks (SSDs), which have gradually replaced hard disk drives (HDDs) in search engines. In this paper, we present an Efficient Data...
Spoof surface plasmon polaritons (SSPPs), as a new frontier in the terahertz (THz) range, is difficult to be effectively directional launched. In this paper, based on the near-field interference of the SSPPs generated by a pair of slits, we demonstrate that the oblique incident plane wave results in the unidirectional excitation of SSPPs. The extinction ration obtained with the finite element method...
OFDM-CPM is now a recognized alternative to conventional OFDM for the transmission of signals over Non-Continuous Wideband channel. This paper presents a characterization of nonlinear distortion effects in orthogonal frequency-division multiplexing/continuous phase modulation (OFDM-CPM) transmission systems on Non-Continuous Wideband. In a second step, a comparison with simulation results is carried...
Emotions convey information. We present an emotion understanding system to excavate information from emotions. The system infers mental states, personalities and cooperativeness of agents, related actions, and related events from agents' emotions by the rule-like meta-knowledge about emotions. Our system can be used for agents to make decisions, process knowledge, and interact with users.
Fast frequency hopping (FFH) is a very effective way to combat jamming. In this paper, low density parity check (LDPC) code is employed to enhance the performance of FFH systems over a frequency-nonselective Rician fading channel under band multitone jamming (BMTJ). Moreover, maximum likelihood (ML) diversity combining and various robust diversity combining techniques which need partial or no side...
In Satellite Communication System, system lifetime drops drastically in energy consumption of the payload. MIMO has been done in order to take advantage of the correlation among satellites' data for increasing the capacity of channel and decreasing the transmission power. This paper studies a dual-satellite scenario based upon synchronization-deriving and gateway-processing schemes, aimed at overcoming...
In this paper, we investigate the relation of Mutual Interference Avoidance and Modulation Mode that aims at maximizing the capacity in OFDM-based opportunity spectrum access(OSA) systems. The continue phase modulation techniques for OFDM systems are considered.We try to decrease the mutual interference between the SUs channel and license frequencies. We show that the traditional PSK modulation with...
Large-scale search engines use hard disk drives (HDD) to store the mass index data for their capacity, whose performances are limited by the relatively low I/O performance of HDD. Caching is an effective optimization, and many caching algorithms have been proposed to improve retrieval performance. Considering the high cost of memory and huge amounts of data, the limited capacity of cache in memory...
As an important part of searching result presentation, query-biased document snippet generation has become a popular method of search engines that makes the result list more informative to users. Generating a single snippet is a lightweight task. However, it will be a heavy workload to generate multiple snippets of multiple documents as the search engines need to process large amount of queries per...
In this paper, we investigate the power allocation strategy that aims at maximizing the capacity in OFDM-based opportunity spectrum access(OSA) systems. The channel estimation techniques for OFDM systems based on pilot arrangement are considered. The combined power-allocation and channel estimation based on comb type pilot arrangement is studied through different strategies .We try to estimate channel...
This study examines different RTK survey systems with different data communication methods. The performances of different RTK are analyzed and compared in terms of system configuration, positioning precision, operation radius, communication method, external information, and cost expense. The results show that RTK data by radio station transmission are with low reliability, high labor-intensity, and...
Network coding has been demonstrated to be able to improve the performance of P2P content distribution. However, it is vulnerable to pollution attacks, leading to substantial performance degradation. Moreover, existing corruption detection schemes for network coding are not applied well to P2P systems. More efficient scheme based on attacker identification is required to thwart such attacks. In this...
The Communication Satellite Location/Cell Location (CSL/CL) integrated navigation system will play key role in all blind war. Recent studies show the CSL can provide location services and satellite communication services. However, CSL can not provide reliable and continuous information at any time, because its signals are often screened or disturbed when the users are in the urban canyon, tree-covered...
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