基于无线通信的接触式带钢板形信号采集系统研制

针对滑环结构的接触式板形测试仪存在的不足,采用无线通信方式,研制了多单片机系统的嵌入式板形信号采集系统,通过光电接近开关的合理安装设计,巧妙解决了检测辊正反转时的信号采集和每组4个传感器信号区分问题,并给出了I2C总线系统中主、从单片机的流程。现场试验表明,在传感器为30组,检测辊10圈/秒转动时,系统的可靠性、数据传输速率和误码率均可满足板形闭环控制的要求。     

Anomaly detection in a mobile communication network

Mobile communication networks produce massive amounts of data which may be useful in identifying the location of an emergency situation and the area it affects. We propose a one pass clustering algorithm for quickly identifying anomalous data points. We evaluate this algorithm’s ability to detect outliers in a data set and describe how such an algorithm may be used as a component of an emergency response management system.

Interconnection networks for parallel molecular dynamics simulation based on hamiltonian cubic symmetric topology

A class of interconnection networks for efficient parallel MD simulations based on hamiltonian cubic symmetric graphs is presented. The cubic symmetric graphs have many desirable properties as interconnection networks since they have a low degree and are vertex- and edge-transitive. We present a method for scheduling collective communication routines that are used in parallel MD and are based on the property that the graphs in question have a Hamilton cycle, that is, a cycle going through all vertices of the graph. Analyzing these communication routines shows that hamiltonian cubic symmetric graphs of small diameter are good candidates for a topology that gives rise to an interconnection network with excellent properties, allowing faster communication and thus speeding up parallel MD simulation.     

Nonlinear electronic circuit, Part II: synchronization in a chaotic MODEM scheme

In this work we present a thorough investigation of the effect of noise (internal or external) on the synchronization of a drive-response configuration system (unidirectional coupling between two identical systems). Moreover, since in every practical implementation of a communication system, the transmitter and receiver circuits (although identical) operate under slightly different conditions it is essential to consider the case of the mismatch between the parameters of the transmitter and the receiver. In our work we consider the non-autonomous 2nd order nonlinear oscillator system presented in [G. Mycolaitis, A. Tamasevicious, A. Cenys, A. Namajunas, K. Navionis, A. N. Anagnostopoulos, Globally synchronizable non-autonomous chaotic oscillator, in: Proc. of 7th International Workshop on Nonlinear Dynamics of Electronic Systems, Denmark, July 1999, pp. 277-280] which is particularly suitable for digital communications.Furthermore, we modified the previous chaotic communication system in order to exhibit enhanced security features. The enhancement in the security of the system is achieved by introducing a set of parameters used in the encoding and decoding of the message signal. We also introduce a time delay parameter in the dynamical system which on the one hand improves the chaotic behavior of the system and on the other hand, adds further security in the encoding-decoding scheme.     

Efficient algorithms for wavelength assignment on trees of rings

A fundamental problem in communication networks is wavelength assignment (WA): given a set of routing paths on a network, assign a wavelength to each path such that the paths with the same wavelength are edge-disjoint, using the minimum number of wavelengths. The WA problem is NP-hard for a tree of rings network which is well used in practice. In this paper, we give an efficient algorithm which solves the WA problem on a tree of rings with an arbitrary (node) degree using at most 3L wavelengths and achieves an approximation ratio of 2.75 asymptotically, where L is the maximum number of paths on any link in the network. The 3L upper bound is tight since there are instances of the WA problem that require 3L wavelengths even on a tree of rings with degree four. We also give a 3L and 2-approximation (resp. 2.5-approximation) algorithm for the WA problem on a tree of rings with degree at most six (resp. eight). Previous results include: 4L (resp. 3L) wavelengths for trees of rings with arbitrary degrees (resp. degree at most eight), and 2-approximation (resp. 2.5-approximation) algorithm for trees of rings with degree four (resp. six).     

On cover-structure graphs

Motivated by a problem in communication complexity, we study cover-structure graphs (cs-graphs), defined as intersection graphs of maximal monochromatic rectangles in a matrix. We show that not every graph is a cs-graph. Especially, squares and odd holes are not cs-graphs.It is natural to look at graphs (beautiful graphs) having the property that each induced subgraph is a cs-graph. They form a new class of Berge graphs. We make progress towards their characterization by showing that every square-free bipartite graph is beautiful, and that beautiful line graphs of square-free bipartite graphs are just Path-or-Even-Cycle-of-Cliques graphs.     

Towards 5G: Performance evaluation of 60 GHz UWB OFDM communications under both channel and RF impairments

Detailed analysis on the impact of RF and channel impairments on the performance of Ultra-Wideband (UWB) wireless Orthogonal Frequency Division Multiplexing (OFDM) systems based on the IEEE 802.15.3c standard, for high data-rate applications using the 60 GHz millimetre frequency band is presented in this paper. This frequency band, due to the large available bandwidth is very attractive for future and 5G wireless communication systems. The usage of OFDM at millimetre-wave (mmWaves) frequencies is severely affected by non-linearities of the Radio Frequency (RF) front-ends. The impact of impairments is evaluated, in terms of some of the most important key performance indicators, including spectral efficiency, power efficiency, required coding overhead and system complexity, Out-Of-Band Emissions (OOBEs), Bit Error Rate (BER) target and Peak Signal-to-Noise Ratio (PSNR). Additionally, joint distortion effects of coexisting Phase-Noise (PN), mixer IQ imbalances and Power Amplifier (PA) non-linearities, on the performance degradation of a mmWave radio transceiver, combined with various multipath fading channels, are investigated. Subsequently, the power efficiency of the system is evaluated by estimating values of the PA Output-Power-Backoff (OBO) needed to meet the requirements for the Transmit Spectrum Mask (TSM) and BER target. Finally, a comparison of the system overall performance between uncoded and coded OFDM systems combined with Quadrature Amplitude Modulations (16 and 64 QAM) and its maximum operable range are evaluated by transmitting a Full HD uncompressed video frame under five different RF impairment conditions over a typical LOS kiosk 60 GHz IEEE channel model.     

An implicit FDTD scheme for the propagation of VLF–LF radio waves in the Earth–ionosphere waveguide

A new finite-difference time-domain scheme is presented for the propagation of VLF–LF radio waves in the Earth–ionosphere waveguide. The new scheme relies on the implicit solution of the auxiliary equation that governs the current density in the ionosphere. The advantages and drawbacks of the new scheme are discussed. Its main advantage is its stability condition, which is the same as that of the FDTD method in a vacuum. This permits the time step of the calculation to be increased and then the overall computational time to be reduced. Numerical experiments demonstrate the accuracy of the new scheme and the reduction of the computational time.     

Evacuation assistants: An extended model for determining effective locations and optimal numbers

The present research presents an extended evacuation field model for simulating crowd emergency evacuation processes under the control of evacuation assistants. Furthermore, a communication field for describing the escape information transmission process and its effect on evacuees is introduced. The effective locations and optimal numbers of evacuation assistants as generated through the model are proposed in an effort to verify as well as enhance existing models. Results show the following. (1) Locating evacuation assistants near exits reduces the time delay for pre-evacuation. (2) There is an optimal number of evacuation assistants for achieving evacuation efficiency; having excessive numbers of evacuation assistants does not improve the evacuation efficiency, and they may result in evacuation time delay and hinder the evacuation efficiency. (3) As the number of evacuees increases, the number of evacuation assistants needed decreases.     

一种基于纠缠态的量子中继通信系统

提出了一种基于纠缠态的量子中继通信系统,该系统应用纠缠为基本资源.纠缠为量子隐形传态和绝对安全的量子通信提供了保证.量子中继器用来延长高纠缠度的纠缠光子对的纠缠距离,利用纠缠交换和纠缠纯化在系统的发信者与受信者之间建立光子对的纠缠.应用量子隐形传态的原理传输量子信息.系统分析表明,量子通信系统的吞吐率随着通信双方成功建立纠缠的概率增大而显著增加,量子信号的传输距离取决于量子中继节点的级数.