Advanced Materials Research Vols. 403-408

Abstract: Wearable, textile-based antennas are dominated research topics for body-centric communications because it could be easily worn on body and integrated into clothes. Since the antenna will operate on a moving person, a circularly polarized antenna is needed in order to optimize the off-body communication link. A wearable circularly polarized textile antenna for body-centric wireless communications is designed in this paper. The proposed antenna is a square-ring microstrip antenna with truncated corners with the bandwidth of 9% when off the body. When it is near the body, we simulate the human body as three-layer model including skin, fat and muscle and put the antenna at different distances to the body. The situation of antenna bending is also simulated at different radii. Specific Absorption Rate was evaluated at last.

Abstract: Hidden terminal problem (HTP) has been a main research aspect in the field of wireless network performance analyzing and testing since it was formulated in 1970s. This article conducts a relatively comprehensive testing on the performance degradation of IEEE 802.15.4 network, which is beacon enabled, star architecture and using slotted CSMA/CA algorithm, due to HTP. All simulate experiments are conducted in NS-2. The experiment results show that: data generation form has little impact on HTP; packet length has more effect on HTP than the number of packets; HTP is trivial when network load is lower than 10%; acknowledge mechanism enlarges extremely HTP; increasing the value of beacon order (BO) is help for alleviating HTP when BO value is small than 6. These conclusions are useful for understanding the features of HTP in IEEE 802.15.4 networks.

Abstract: Aiming at the problem that the radiation monitoring system has high cost, big power consumption, and complex process of system constructing, a new wireless network radiation monitoring system is presented and implemented for radiation detection. This system adopts ZigBee technology and GPRS communication technology to realize the communication of real time data. Namely, this system uses ZigBee wireless protocol stack as control core, and adopts GPRS network as output transmission. Then build a FTP server to achieve the monitoring, statistics and alarm function of radiation dose.

Abstract: Information asymmetry exists in a game relation between GM food Production enterprises and Regulators. Thus the market equilibrium depends on the strategy of GM food Production enterprises and Regulators.This paper argues that the probability of GM food Production enterprises paying attention to the propaganda and labeling GM food Consciously increase along with the probability of Regulation whether in Dynamic Game or Static Game. For the sake of Consumers,the Regulation of GM food is Essential.

Abstract: In this paper,the transveral force on uniform FBG is specially analyzed according to the couple-mode theory and the corresponding mathematical model is established. Studies show that when the FBG under local transverse force, the length of pressure has no effect on the reflection spectrum. The wavelength of the reflection spectrum splitting point and lateral force possessed a direct proportional linear correlation, and has periodicity at the same time. The split point reflectivity and the force position approximately have hyperbolic tangent relationship.

Abstract: Integer carrier phase ambiguity resolution is the key to fast and high-precision Global navigation satellite system(GNSS) positioning and application. LAMBDA method is one of the best methods for fixing integer ambiguity. The principle of LAMBDA is discussed. For incompleteness of Cholesky decomposition and complexity of Integer Gauss transformation, a new approach for GNSS ambiguity decorrelation is proposed based on symmetric pivoting strategy and united inverse integer strategy. The new algorithm applies symmetric pivoting strategy to ambiguity covariance matrix while doing Cholesky decomposition, then finds the inverse and integer matrix of ‘L’. This method not only uses Cholesky decomposition to improve efficiency, but also avoids complicated Integer Gauss transformations. The feasibility and advantage of the method are verified using randomly simulation covariance matrix.

Abstract: Providing Machine-to-Machine (M2M) services is not only an opportunity but also a big challenge for telecom operators. Currently, the categorization of M2M services is mainly based on the serving field. Because the serving field is very large and new services will come up along with the progress of market, it is difficult for operators to provide services according to the serving field. Based on the real requirements from the operators and venders, there are 14 service features defined by 3GPP. However, the relation of different features is unclear. A new categorization method for M2M services based on the traffic characteristics is proposed in this paper. Based on the four traffic characteristics, including content type, data amount, transmission mode and priority of transferring, the M2M services are divided into five categories: mobile streaming, smart metering, regular monitoring, emergency alerting and mobile POS. Furthermore, the service characteristics and network requirements of each category are also analyzed.

Abstract: The traditional K-means clustering algorithm prematurely plunges into a local optimum because of sensitive selection of the initial cluster center. Hierarchical clustering algorithm can be used to generate the initial cluster center of K-means clustering algorithm. The geometric features of input data can achieve a good distribution by means of pretreatment and feature extraction and selection. In the learning of fuzzy neural network, Java language is used to write source code of the algorithm. The experimental results show that new algorithm has improved the clustering quality effectively.

Abstract: General data-processing board is designed based on POWERPC as its main processor, by extending the module of FPGA, DSP and voice circuit, also integrating Ethernet and LVDS to achieve the dual access of voice and data, in order to achieve data processing and analysis. This paper explains the general framework of data processing board, and the interface and controlling between host controller and each extensions of module, finally, explores a simple program to debug the data processing board, in order to determine the reliability and utility of the data processing board.

Abstract: Intrusion detection for network security is an application area demanding high throughput. The pattern matching in intrusion detection requires extremely high performance to process string matching. Most of pattern matching using software has many time complexities and cannot reach the requirements of high throughput. The pattern matching using hardware considerably improves the speed of matching and has several other advantages. This paper describes a FPGA-based pattern matching architecture, using hashing method called XOR Hashing. The proposed method updates new patterns without reconfiguration and processes the collision and has high matching performance. The proposed system implements the pattern matching by using Snort rule-set, an open source Network Intrusion Detection and has simulation processing on PC. Compared with existing hardware method, the results explained that our method has relatively high performance for the pattern matching and can else process the pattern matching with high performance on low–cost FPGA device.