中文摘要：

近年来，无线传感器网络的安全研究越来越受到关注，研究者们相继提出了许多解决方案。其中的随机密钥预分配方案基于概率模型，因此网络中可能存在着一些安全孤立节点，从而可能会降低整个网络的安全连通性。针对此问题，提出在节点布置比较稀疏的无线传感器网络的初始化阶段以及网络在运行过程中，定期对网络进行安全连通性检测，以发现网络中存在的安全孤立节点，然后增大这些孤立节点的通信半径，从而动态地调整网络中某个局部区域的安全连通性，以使得整个网络获得更高的安全连通性。

英文摘要：

In recent years,researchers are paying more and more attentions on security issues in Wireless Sensor Networks （WSNs）,and many solutions on these issues have been proposed.Due to the fact that the random key pre-distribution scheme is based on probability model,it is possible that some isolated nodes regarding security may exist in WSNs,and thus reducing the secure connectivity of the whole network.At the stages of both the network initialization and network operation,an improved scheme is proposed that can dynamically adjust the local connectivity of the network by means of extending the nodes＇ communica- tion range and detecting the secure connectivity in WSNs.Then higher secure connectivity can be achieved in the whole network.