一种基于 XC7VX690T 和 XC7Z045的数字信号处理及网控模块设计

随着数字信号处理技术的高速发展,人们对数字信号处理及网络控制的需求越来越强烈。文章重点介绍了一种基于 XC7VX690T 和 XC7Z045 的数字信号处理及网控模块设计,着重从电源电路、时钟电路、存储电路以及对外接口电路等多方面实现该模块的硬件功能,为后续的软件应用提供硬件基础,然后介绍了数字信号处理及网控模块的工作流程,实现了数字信号处理及网控功能。

Key Techniques of Frequency Synthesizer for WLAN Receivers

Several key techniques for a PLL-type frequency synthesizer for WLAN receivers are studied. Its structure is analyzed and the main parameters are proposed. A monolithic LC-tuned voltage controlled oscillator （LCVCO） with low phase noise is fabricated with TSMC 0.18μm RF （radio frequency） CMOS technology. The measured phase noise is - ll7dBc/Hz at 4MHz off the center frequency of 4. 189GHz. A down-scaling circuit with low power dissipation was fabricated in a TSMC 0.18μm mixed-signal CMOS process. The measured results show that the IC can work well under a 1.8V power supply. Its total power dissipation is only 13mW.

SGuard：A Lightweight SDN Safe-Guard Architecture for DoS Attacks

Software Defined Networking(SDN) is a revolutionary networking paradigm towards the future network,experiencing rapid development nowadays.However,its main characteristic,the separation of control plane and data plane,also brings about new security challenges,i.e.,Denial-of-Service(DoS) attacks specific to Open Flow SDN networks to exhaust the control plane bandwidth and overload the buffer memory of Open Flow switch.To mitigate the DoS attacks in the Open Flow networks,we design and implement SGuard,a security application on top of the NOX controller that mainly contains two modules:Access control module and Classification module.We employ novel six-tuple as feature vector to classify traffic flows,meanwhile optimizing classification by feature ranking and selecting algorithms.All the modules will cooperate with each other to complete a series of tasks such as authorization,classification and so on.At the end of this paper,we experimentally use Mininet to evaluate SGuard in a software environment.The results show that SGuard works efficiently and accurately without adding more overhead to the SDN networks.

Application of the Keyword Recognition in the Network Monitoring

In this paper, the specific application of key words Spotting used in the network monitoring is studied, and the keywords spotting is emphasized. The whole monitoring system is divided into two mod-ules： network monitoring and keywords spotting. In the part of network monitoring, this paper adopts a method which is based on ARP spoofing technology to monitor the users＇ data, and to obtain the original audio streams. In the part of keywords spotting, the extraction methods of PLP （one of the main characteristic arameters） is studied, and improved feature parameters- PMCC are put forward. Meanwhile, in order to accurately detect syllable, the paper the double-threshold method with variance of frequency band method, and use the latter to carry out endpoint detection. Finally, keywords recognition module is built by HMM, and identification results are contrasted under Matlab environment. From the experiment results, a better solution for the application of key words recognition technology in network monitoring is found.

Controller Design of Intelligent Lighting Network

Studied are the controller design and basic principles of intelligent lighting network. TI’s MSP430F123 is used as a main controller. By using the ZigBee modules(Xbee/Xbee-PRO) and the GSM module(SIM300C) for wireless communications, the lighting control is enabled to access wireless network. This system uses a mobile phone to achieve light on-off directly, which can accomplish wireless control of intelligent lighting in families.

A modular multilevel power flow controller for meshed HVDC grids

Based on the comparison of existing power flow controllers(PFC)in meshed HVDC grids,the full-bridge modular multilevel converter based PFC(MMPFC)is proposed.At first,the general branch current calculation method of meshed HVDC grids with the PFC is presented,and then,the issue of over-voltage on the thyristor based PFC is described and analyzed.Through the analysis of different operating modes of the full-bridge sub-module,the mechanism of over-voltage ride through of the MMPFC is indicated.The control strategy of the MMPFC,which is used to control branch current and keep capacitor voltage balancing,is elaborated.Finally,the performance on current regulation,bidirectional operation and over-voltage ride through is simulated and verified in a built model with PSCAD/EMTDC.

Topological origin of global attractors in gene regulatory networks

Fixed-point attractors with global stability manifest themselves in a number of gene regulatory networks. This property indicates the stability of regulatory networks against small state perturbations and is closely related to other complex dynamics. In this paper, we aim to reveal the core modules in regulatory networks that determine their global attractors and the relationship between these core modules and other motifs. This work has been done via three steps. Firstly, inspired by the signal transmission in the regulation process, we extract the model of chain-like network from regulation networks. We propose a module of "ideal transmission chain(ITC)", which is proved sufficient and necessary(under certain condition) to form a global fixed-point in the context of chain-like network. Secondly, by examining two well-studied regulatory networks(i.e., the cell-cycle regulatory networks of Budding yeast and Fission yeast), we identify the ideal modules in true regulation networks and demonstrate that the modules have a superior contribution to network stability(quantified by the relative size of the biggest attraction basin). Thirdly, in these two regulation networks, we find that the double negative feedback loops, which are the key motifs of forming bistability in regulation, are connected to these core modules with high network stability. These results have shed new light on the connection between the topological feature and the dynamic property of regulatory networks.