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Due to the complexity of the hearts anatomy blurred boundaries of its surrounding organs in cardiac CT images, the whole heart segmentation is still a big challenge. In this paper, method based on watershed and active contour models were proposed for the whole heart CT image segmentation task. Firstly, the Bilateral filtering approach is used to eliminate the noise of the cardiac CT images. Then, the watershed segmentation method is applied to determine the initial seed contours. Finally, the active contour model is adopted in the evolve process iteratively with the previous contour to obtain the precise segmentation boundaries for whole heart CT images. The performance is evaluated with a clinical cardiac CT images dataset, which proved good segementation results as well as the high robustness.

In order to solve the problem of complicated calculation and frequent human intervention, a new method for extracting the centerline of blood vessel based on magnetic resonance angiography (MRA) is proposed in this paper. First of all, according to the different diameter of blood vessels, the multi-scale filtering algorithm is utilized for enhancing the different scales of blood vessels by Hessian matrix. The discriminant function is established based on the gray distribution of the blood vessel and the differential operator, and then the initial position and the orientation direction of the seed point are obtained. Secondly, the new ridge point and tracing direction are optimized in the local arc length range of the initial direction to ensure that the correct ridge point position can be obtained even with large error interference. Finally, we eliminate pseudo-centerlines that do not satisfy the initial conditions and get the final centerline of the vessel to be extracted. The experimental results show that this method can automatically extract the blood vessel centerline from the MRA images without manual intervention.

In this paper, we propose a mixing white light antenna with a homogenizer and an amplification system, and demonstrated its utilization in a four-spectrum mobile VLC. The central element is the homogenizer, which is a square integrating rod that mixes four-spectrum light into white light. Behind it, there are two Fresnel lenses to amplify the light-mixing area. The system is compact with a length of 80 mm and maximal diameter of 58.5 mm. We determined the initial structural parameters of the antenna by theoretical analysis, and then we determine the best parameters by simulation. Simulation results indicate that a 0.75 m×0.75 m area can be illuminated at 1.7 m distance. The detection surface has a high uniformity (76.27%), which can meet illumination and mobile communication requirements simultaneously.

As the traditional frequency and time offset estimation method is complex and sensitive to the frequency offset, in this paper, the process of the initial cell search is described, the reason why the M-segment partial correlation bringing down the risk of incorrect detection of time offset is analyzed. Based on the time offset detected by M-segment partial correlation and the result of ML (Maximum Likelihood) estimation which is proved by Jan-Jaap, a method improving the success probability of initial cell search in the low SNR condition is proposed. In the simulation environment, the performance of the proposed method is compared with the traditional method, proving the proposed method not only less sensitive to frequency offset, but also effective.

AODV is an on-demand routing protocol for mobile ad hoc network, with advantages of low load of control, low power consumption as well as low-bandwidth overhead. The routing table in AODV, however, maintains only one route to the specified node. Therefore, the source node needs to re-initiate route discovery process as a route fails. To solve this problem, an improved method is presented in this paper. The proposed scheme suggests that each source node maintains an alternative route to the specified destination node. When the primary route fails, the source node will use the backup route to send packets. Simulation results show that this modification can not only improve the packet delivery fraction but also reduce the average end to end delay, the routing overhead and the route discovery frequency.

Pseudo-orthogonal space-time block coded OFDM system (POSTBC-OFDM) has recently been proposed as a novel scheme for the frequency-selective channel scenario. However, a general assumption underlying the use of space-time codes is that the channel should be quasi-static, which is violated from the nature of high mobility environment. Additionally, large Doppler spread causing rapidly time-varying channels could destroy the orthogonality among neighboring subcarriers and lead to intercarrier-interference (ICI). This paper studies the extension of the POSTBC-OFDM scheme to the rapidly time-varying channel case by adopting sectorized antenna reception technique which could reduce Doppler spread and the channels time-variance by restricting the incident angle of imping waves to a finite range. Simulation results show that this proposed system is not only suitable for high mobility condition, but also can get a better tradeoff among performance, code rate and complexity of receiver.

This paper establishes the emergency problem tree model and knowledge-base based on emergency problem, and then proposes an approach of problem solving. The problem tree model describes the problem structure and the relationships between problems, which can build the contact between problem and knowledge-base. It provides a variety of knowledge and method for decision-makers and help to improve the ability of the prevention and handling emergencies.

Applying smart antennas to an OFDMA system is investigated. A simple resource allocation scheme for array-antenna based OFDMA systems is proposed. The resource allocation algorithm is applied to the pilot data when no beam is formed and channel estimation in frequency-domain is implemented. After piloting, a beam is formed for each user to enhance the performance of the system. Simulations based on the SUI channel model according to the standard of IEEE 802.16e WMAN are carried out to examine the performance of the proposed approach.

Two new space-time channel models are introduced for simulating 2 GHz wireless mobile communication systems in outdoor environments. The models combine in reason the power and delay parameters in different environments provided by ITU or 3GPP and the angle parameters generated according to 3GPP/3GPP2 joint spatial channel modeling adhoc. The new models can be directly used in the simulations of TD-SCDMA systems and can be easily extended for application to wireless systems in other frequency bands.

A Laplace power azimuth spectrum distribution model is applied to the analysis of the performance of a beamformer in CDMA communication systems. The effects of angle spread on beamforming in both the uplink and the downlink are investigated. Compared to a single-antenna-based system, the array processing gains of a mobile communication system with a smart antennas array are derived. Numerical results for a uniform linear array and a uniform circular array, respectively, are provided.