中文摘要：

Stack Exchange是目前最流行的问答社区集结地之一.本文利用Stack Exchange中具有美国地理信息的用户构建Stack Exchange问答社区在美国境内的知识传播图谱,对传播网络的统计特征进行了分析,提取出问答社区类网站的传播模式,获取得到网络用户的知识分享方式.我们发现Stack Exchange中的问答社区在分享知识过程中,传播源往往不止一个.同时,我们为问答社区构建了知识传播图谱,发现这些传播图谱具有相似的统计特征,这意味着不同的问答社区可能具有类似的知识传播模式.

英文摘要：

Stack Exchange is one of the most popular QA rendezvous, including dozens of QA communities. In the paper, based on the QA relationships and the geographical information of users, this paper analyzes the knowledge spreading patterns in QA communities in Stack Exchange in USA and statistical characters of networks. It extracts spreading patterns of QA communities and obtains knowledge sharing methods of users. We find that, generally, a QA community may have several spreading sources. Meanwhile, it establishes a spreading network for each QA community and finds that most of these spreading networks share similar statistical characters, indicating that these QA communities have similar spreading patterns.