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A subband excitation substitute based scheme for narrowband speech watermarking

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Frontiers of Information Technology & Electronic engineering 2017年第5期18卷 627-643页

作者： Wei LIU Ai-qun HU school of lnformation Science and engineering Southeast UniversityNanjing 210096China

We propose a new narrowband speech watermarking scheme by replacing part of the speech with a scaled and spectrally shaped hidden signal. Theoretically, it is proved that if a small amount of host speech is modified, then not only an ideal channel model for hidden communication can be established, but also high imperceptibility and good intelligibility can be achieved. Furthermore, a practical system implementation is proposed. At the embedder, the power normalization criterion is first imposed on a passband watermark signal by forcing its power level to be the same as the original passband excitation of the cover speech, and a synthesis filter is then used to spectrally shape the scaled watermark signal. At the extractor, a bandpass filter is first used to get rid of the out-of-band signal, and an analysis filter is then employed to compensate for the distortion introduced by the synthesis filter. Experimental results show that the data rate is as high as 400 bits/s with better bandwidth efficiency, and good imperceptibility is achieved. Moreover, this method is robust against various attacks existing in real applications.

关键词： Analysis filter Linear prediction Narrowband speech watermarking Passband excitation replacement Power normalization Spectral envelope shaping Synthesis filter

Tunable ponderomotive squeezing induced by Coulomb interaction in an optomechanical system

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Chinese Physics B 2016年第1期25卷 446-451页

作者：吴琴 school of lnformation engineering Guangdong Medical UniversityDongguan 523808China

We investigate the properties of the ponderomotive squeezing in an optomechanical system coupled to a charged nanomecbanical oscillator （NMO） nearby via Coulomb force. We find that the introduction of Coulomb interaction allows the generation of squeezed output light from this system. Our numerical results show that the degree of squeezing can be tuned by the Coulomb coupling strength, the power of laser, and the frequencies of NMOs. Furthermore, the squeezing generated in our approach can be used to measure the Coulomb coupling strength.

关键词： ponderomotive squeezing Coulomb interaction optomechanical system

A Novel Onboard-gateway-based Mechanism to Improve TCP Performance in Aeronautical Satellite Networks

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Chinese Journal of Aeronautics 2007年第3期20卷 260-265页

作者： GU Ming ZHANG Jun school of Electronics and lnformation engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The IP-based networks on aircraft serve to support Intemet services via satellites. However, in aeronautical satellite hybrid networks, the TCP protocol performance often deteriorates due to improper decreases and slow recovery of the congestion window. This paper proposes a window size determination and notification mechanism, onboard-gateway-based mechanism （OGBM）, which is based on the onboard gateway in the networks on aircraft. A cross-layer approach is adopted by the onboard gateway to obtain the satellite link bandwidth information. And then, by the gateway, through changing the receiver＇s advertised window field in ACK packets, TCP sources are notified of the window size of each TCP source calculated on the ground of bandwidth delay product and flow numbers. The mechanism is able to avoid improper changes of TCP window and serve multiple users. Simulation results show that the mechanism with the fairness index close to l improves TCP performance in aeronautical satellite networks.

关键词： congestion control TCP gateway aeronautical satellite network

Core-based Shared Tree Multicast Routing Algorithms for LEO Satellite IP Networks

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Chinese Journal of Aeronautics 2007年第4期20卷 353-361页

作者： Cheng Lianzhen Zhang Jun Liu Kai school of Electronics and lnformation engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

A new core-based shared tree algorithm, viz core-cluster combination-based shared tree （CCST） algorithm and the weighted version （i.e. w-CCST algorithm） are proposed in order to resolve the channel resources waste problem in typical source-based multicast routing algorithms in low earth orbit （LEO） satellite IP networks. The CCST algorithm includes the dynamic approximate center （DAC） core selection method and the core-cluster combination multicast route construction scheme. Without complicated onboard computation, the DAC method is uniquely developed for highly dynamic networks of periodical and regular movement. The core-cluster combination method takes core node as the initial core-cluster, and expands it stepwise to construct an entire multicast tree at the lowest tree cost by a shortest path scheme between the newly-generated core-cluster and surplus group members, which results in great bandwidth utilization. Moreover, the w-CCST algorithm is able to strike a balance between performance of tree cost and that of end-to-end propagation delay by adjusting the weighted factor to meet strict end-to-end delay requirements of some real-time multicast services at the expense of a slight increase in tree cost. Finally, performance comparison is conducted between the proposed algorithms and typical algorithms in LEO satellite IP networks. Simulation results show that the CCST algorithm significantly decreases the average tree cost against to the others, and also the average end-to-end propagation delay ofw-CCST algorithm is lower than that of the CCST algorithm.

关键词： satellite IP networks LEO multicast routing shared tree core

Up-conversion photoluminescence emissions of CaMoO4：Pr3＋/Yb3＋ powder

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Journal of Rare Earths 2017年第7期35卷 645-651页

作者：李金萍张婷婷朱刚强郑海荣 school of Physics and lnformation Technology Shaanxi Normal University Xi'an 710062 China

CaMoO_4：Pr^（3＋）/Yb^（3＋） powder was successfully synthesized by a facile hydrothermal method. X-ray diffraction（XRD） patterns of samples confirmed tetragonal structure and morphology and sizes were confirmed by scanning electron microscopy（SEM） analyses. Particles consisted of regular micro-spheres with uniform sizes, the diameter of each sphere lay in the range of 3 to 4 μm. The up-conversion photoluminescence emission and its concentration dependence were investigated under infrared excitation at 980 nm. All the UC micro-particles exhibited the typical blue, green and red emissions. Dominant blue emissions originated from ~3P_0→~3H_4 and intense red emissions originated from ~3P0→~3F_2 transitions, and they both belonged to two-photon excitation processes in CaMoO_4： Yb^（3＋）/Pr^（3＋） powder. The optimum doping concentrations of Pr^（3＋） and Yb^（3＋） for the highest UC luminescence were 0.1 mol.% and 16 mol.%, respectively. The possible up-conversion mechanisms were discussed in detail. It was found that the UC emission could be well controlled from blue to green to white color by adjusting the concentration of Pr^（3＋） ions in CaMoO_4：Pr^（3＋）/Yb^（3＋） microcrystal. So it is a candidate material for solid-state lasers, biological imaging, solar cells, and optical communications.

关键词： up-conversion luminescence rare earths optical properties hydrothermal method

Explosion limits for combustible gases

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Mining Science and Technology 2009年第2期19卷 182-184页

作者： TONG Min-ming WU Guo-qing HAO Ji-fei DAI Xin-lian school of lnformation and Electrical engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

Combustible gases in coal mines are composed of methane, hydrogen, some multi-carbon alkane gases and other gases. Based on a numerical calculation, the explosion limits of combustible gases were studied, showing that these limits are related to the concentrations of different components in the mixture. With an increase of C4H10 and C6H14, the Lower ExplosionLimit （LEL） and Upper Explosion-Limit （UEL） of a combustible gas mixture will decrease clearly. For every 0.1% increase in C4H10 and C6H14, the LEL decreases by about 0.19% and the UEL by about 0.3%. The results also prove that, by increasing the amount of H2, the UEL of a combustible gas mixture will increase considerably. If the level of HE increases by 0.1%, the UEL will increase by about 0.3%. However, H2 has only a small effect on the LEL of the combustible gas mixture. Our study provides a theoretical foundation for judging the explosion risk of an explosive gas mixture in mines.

关键词： coal mine gas explosive gases explosion limits

A MIMO system with finite-bit feedback based on fixed constellations

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Science China(Information Sciences) 2013年第6期56卷 25-38页

作者： WANG HaiQuan ZHAO ZhiJin school of communications engineering Hangzhou Dianzi University

In this paper,a MIMO system with finite-bit feedback based on fixed constellations is *** on performance analysis of the system,an optimal operating system with maximum-likelihood decoding is ***,this operation reveals that the optimal way for the system to transmit signals needs to invoke the multimode *** propose designing criteria for this scheme and methods for pre-codebooks,and a method to determine the number of modes for any specific ***,to reduce encoding complexity at the receiver side,we also develop a fast encoding *** analysis and simulations show that the proposed systems offer considerable gain over existing ***,these systems also have much lower encoding ***,for the case of a MIMO system with two pairs of transmitting and receiving antennas,a properly designed system with a transmission rate of 8 bits per channel use and with 6-bit feedback can provide about a 1.5 dB performance gain over a beamforming system.

关键词： beamforming fixed constellations finite-bit feedback multiple-input multiple-output systems space-time coding union bound

Simulation Study and Probe on UWB Wireless Communication in Underground Coal Mine

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Journal of China University of Mining and Technology 2006年第3期16卷 296-300页

作者： WANG Yan-fen WANG Zheng-gang YU Hong-zhen school of lnformation and Electrical engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

From an analysis of the status of coal mine underground wireless communication, the application of UWB wireless communication system to underground coal mine is proposed. The basic composition of an UWB communication system and application in underground coal mines are introduced. The analyses show that, because of the transmission power being non-limitted in underground coal mines, the use of UWB in coal mines cannot only realize wireless access services of short distance high rate application for transmission of video monitoring signals, but also realize wireless access services of long distance low rate applications for mobile telephones in underground coal mines and parameters of working conditions monitoring, etc. It is emphasized on the simulation of a TH-PPM UWB communication system with traditional underground broadband model and ground CM1, CM3 model. It is shown that the traditional underground broadband model and ground CM1, CM3 models are not applicable to the UWB communication system in underground coal mines. It is necessary to conduct research on the propagation characteristics of UWB in coal mine tunnels, given the characteristics of the underground environment and to find the appropriate UWB model for underground coal mines.

关键词： ultra-wide band system simulation underground coal mine channel model characteristic of propagation.

A Heuristic Genetic Algorithm for No-Wait Flowshop Scheduling Problem

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Journal of China University of Mining and Technology 2007年第4期17卷 582-586页

作者： CHANG Jun-lin GONG Dun-wei MA Xiao-ping school of lnformation and Electrical engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

No-wait flowshop scheduling problems with the objective to minimize the total flow time is an important se-quencing problem in the field of developing production plans and has a wide engineering background. Genetic algo-rithm (GA) has the capability of global convergence and has been proven effective to solve NP-hard combinatorial op-timization problems,while simple heuristics have the advantage of fast local convergence and can be easily imple-mented. In order to avoid the defect of slow convergence or premature,a heuristic genetic algorithm is proposed by in-corporating the simple heuristics and local search into the traditional genetic algorithm. In this hybridized algorithm,the structural information of no-wait flowshops and high-effective heuristics are incorporated to design a new method for generating initial generation and a new crossover operator. The computational results show the developed heuristic ge-netic algorithm is efficient and the quality of its solution has advantage over the best known algorithm. It is suitable for solving the large scale practical problems and lays a foundation for the application of meta-heuristic algorithms in in-dustrial production.

关键词： production scheduling genetic algorithm flowshop no-wait