Search

Due to the multipath fading and wall occlusion, Global Positioning System (GPS) doesn't work very well indoors. Therefore, indoor visible light positioning (IVLP) method based on Received Signal Strength (RSS) is adopted as a supplement to GPS system for indoor positioning. However, thermal noise and shot noise reduce the positioning accuracy of IVLP system significantly. In this paper a solution is proposed to improve the positioning accuracy. Firstly, the adaptive filtering method is used to reduce noise in the received signal. Secondly, the least square method is adopted to estimate the unknown coordinates of the target. The simulation results show that the positioning errors of 1681 detection points in a are less than 0.01m in a 4m×4m×3m room under 5db and 10db noise. Therefore, the method has a certain ability to suppress noise.

Aiming at the problems of time delay of fusion center in multi-missile cooperative target detection system due to the different starting time of sensor measurement of each missile, a time registration algorithm based on modified gain extended Kalman filter (MGEKF) is introduced. In this algorithm, the extended Kalman filter (EKF) is improved to carry out high-precision unbiased estimation of the target motion state, which is used for time compensation of the target motion state estimation of the missiles, and data fusion is conducted from the estimation registration of the missiles motion state to the fusion moment. The simulation results show that the algorithm can effectively reduce the system time registration error, improve the system time registration accuracy, and provide a good foundation for data fusion.

The refractive index of a lens varies for different wavelengths of light, which causes chromatic aberration. Although most camera lens are achromatic, but the residual chromatic aberration still decrease the image’s quality and the measurement accuracy seriously. In this paper, the camera lens chromatic aberration models for commercial camera lens are analyzed by experiments, and the optimized model is determined. According to the model, method for compensating chromatic aberration is given in this paper. The experiments have shown that the proposed method can eliminate the influence of chromatic aberration effectively.

In this paper, the fast finite-time consensus tracking problems of the second-order leader-following multi-agent systems are investigated. First, an improved fast finite-time consensus tracking algorithm is presented that based on the gradient algorithm of the overall cost function. Second, we prove that the leader-following fast finite-time consensus can be achieved in finite time with the fixed and switching directed topologies. Finally, some simulation examples illustrate the superiority of the improved algorithm.

Because of the advantages of high measurement accuracy and efficiency, the structured light method has been become a research hotpot in 3D measurement field. The stripe pattern has been widely used in structured light system because of the advantages of anti-noise and high accuracy. Modulated by color and shape of the measurement object, the distribution of the stripe is degenerated. The accuracy of stripe center location, which is a key factor of measurement accuracy, is decreased by the degeneration. In this study, a method for modeling the distribution of stripe in shot image is proposed. Based on the method, several factors which influence the accuracy of locating the stripe center are simulated and analyzed. Furthermore, the performance of typical methods for locating stripe center are simulated. The experiments verified that the method does work. This method not only provide evidence for calculating the measurement accuracy of specific object, but also provide a tool to assess the performance of method for locating stripe center.

Registration of pathological section images is an important part of three-dimensional reconstruction of sections. In this paper, a registration method was proposed to solve the problem of mismatching of pathological section images of pulmonary nodules. Firstly, rough matching is performed, and the feature points are extracted according to the scale-invariant feature transform (SIFT) algorithm. Then fast sparse coding (FSC) is used for fine matching to eliminate mismatched pairs. The algorithm presented in this paper is applied to the registration between sequence sections of pulmonary nodules. The experimental results show that the algorithm can effectively find more matching point pairs, accurately remove the false matching point pairs, and significantly improve the registration accuracy.

Any threat to the safety of tourists causes a decrease or total absence of activity, not only in a particular tourism enterprise, but also very often in destinations, neighboring regions or countries as well. As the same as the marketing product life-cycle, tourism crisis also has life-cycle and shows different characteristics in diferent stages. This paper defines and explaines tourism crisis life-cycle, analyzes its characteristics in every stage. It also put forward some suggestions for tourism destination to deal with crisis exactly on the basis of crisis lifecycle, such as the pre-warning management in prodromal stage, responsing and mitigating management in acute and chronic stage, recovering management in resolution stage.

My article proposed a framework structure of expert system based on simplify rete inference algorithm, This framework structure is general and flexible, it reduced the degree of difficulty to expert system' achieve in all fields. In other hand, building a general and flexible framework of expert system, which can be adjusted dynamically to fulfill the need in different application fields.

For the problem of perceptual cognition about current products modeling features singly, this paper proposes a layered general deconstruction method to obtain all multi-dimensional modeling features (MMFs) by deconstructing the product’s components as human interface elements (HIEs) from the angle of multi-sense channels. Then it establishes a Kansei Engineering (KE) model between products’ MMFs and emotions based on the consumer-oriented experiments. By comparing analytical results of the comparative experiment, it points out that to cognize the MMFs simultaneity agrees with human cognitive characteristics, is an effective way to optimize the performance of the Kansei Engineering model and effectively solve the problem of perceptual cognition about products modeling features singly.

The thesis, from the perspective of human cognition, putted forward a new systematical deconstruction method based on the human interface, that is, to deconstruct a product by certain level into the human interface elements( HIEs) and the element logics. Then, on the basis of the kansei engineering technology, it constructed kansei engineering models respectively for the overall HIEs deconstruction pattern and the singular HIE deconstructing pattern, and compares their performances. By comparing the analytical results and validating the tested samples, it pointed out that the overall HIEs pattern, whose kansei engineering model was better at forecasting and illustrating emotions, agrees with human cognitive characteristics, was an effective way to optimize the performance of the kansei engineering model, and will be helpful to the research of kansei engineering.

More and more large amounts of data shared with researchers and workstations worldwide are generated by scientific experiments and engineering applications. High performance grids aim at facilitating the distribution of such data to geographically remote places. For high performance data grids where users require remote access to large files, dynamic replication is an efficient method to improve performance. In this paper, Fast Cascading, a new dynamic replication algorithm, is proposed for the multi-tier Data Grid. The simulation results obtained by Simulator OptorSim which has been modified show that this algorithm can reduce the average response time of data access greatly for random access pattern compared with other algorithms,such as Fast Spread, LRU and Economy-Zipf dynamic replication strategy, and the gain increases with the number of jobs submitted.

Network lifetime is an important metric for battery operated sensor networks. In this paper, we study the lifetime of a general sensor network with n randomly deployed sensors communicating with a base station (BS). We show how the lifetime of such sensor networks is influenced by transmission schemes, network density and transceiver parameters with different constraints on network mobility, position awareness and maximum transmission range. Our results offer insight into the network deployment and protocol design that optimize the network lifetime.

We propose a link layer security framework, named SecureSense that provides energy efficient secure communication in sensor networks. Using runtime security service composition, the proposed SecureSense enables a sensor node to optimally allocate its resources (CPU cycles, memory consumption and RF messages) to appropriate security services depending on observed external environments, internal constraints and application requirements. SecureSense service composition varies with respect to both security provision strength (how easy it can be broken) and security concerns (e.g., integrity vs. confidentiality). Compared to a stationary security model with maximum security provision, our scheme can significantly prolong the network lifetime without degrading the security requirements of the applications.

The provision of anytime anywhere communication is a challenging task for Internet service providers. Combining the high data rate of IEEE 802.11 wireless LANs and multihop connectivity of ad hoc networking, hybrid networks like mesh wireless LANs are an attractive solution for ubiquitous mobile access to the Internet. We introduce a lightweight proactive routing protocol for the ubiquitous mobile access networks named adaptive mobile access routing (AMAR). Simulation results show that the proposed routing protocol provides reliable data delivery, and swiftly reacts to the network changes with low overhead. The proposed ubiquitous mobile access network architecture and the AMAR protocol provide an efficient solution for high data rate full coverage wireless Internet access in public areas, e.g., campuses, buildings and airports.

Due to the speed mismatch between wired and wireless networks, network congestion can easily occur at the fusion point (gateway or access point) that interconnects these two networks. In this paper we propose a congestion control scheme for TCP traffic retrieved by wireless LAN clients from the Internet, denoted as media access delay regulator (MADR). The proposed scheme is based on active queue management principles adapted for wireless media. MADR dynamically adapts the MAC layer queue size in order to maintain the average media access delay of packets entering the wireless LAN. The proposed congestion control scheme, MADR, extends the control principles of the PI controller which was first proposed as an AQM scheme for wired networks. Instead of using the reference queue size as the control target, we control the medium access delay of the AP, which reflects the congestion level of the wireless channel. We have implemented our scheme in OPNET simulator. The simulation results show that the proposed scheme maintains the average medium access delay under dynamic traffic patterns and varying channel capacity.