Pair key establishment is a fundamental security service in wireless sensor networks (WSNs); it enables sensor nodes to communicate securely with each other using cryptographic techniques. However, due to the resource constraints, establishing pairwise keys in sensor networks is a challenging problem. Several key management schemes have been proposed in literature to establish pairwise keys between sensor nodes; they either too complicated, or insecure for some common attacks. To address these weakness, we propose an efficient pairwise key management scheme in this paper. In the proposed scheme, the sensor nodes are divided into groups and any compromised sensor node will not disclose the key information in the sensor nodes in same group. The analysis shows that compared with existing approaches, this proposed scheme has better network resilience against node capture attack.

The license plate recognition system, the license plate location is one of the important technologies, can accurately complete the orientation will directly affect the follow-up of the character segmentation and recognition. This paper presents a new color on discrimination based on characteristics of the vehicle license plate location, Firstly, edge detection, image enhancement preprocessing, effectively highlighting the license plate features, And then by line scanning of the plate rough location, and color-based features to distinguish the license plate location method further extract the real license plate. Experiments show that with the car in a complex background, this method can accurately locate the license plate.