JiYin hydraulic project is located at the branch of Keliya River, Yutian county of Xinjiang. During the stage of its planning and design, a magnitude 7.3 earthquake occurred 43km away from the southeast of the dam. As the earthquake was in the southeastern part of Altyn Tagh Fault which was recognized in the past as a low seismicity segment, the cognition about seismic surroundings had changed totally. Based on comparison between the two seismic safety evaluations on JiYin before and after the earthquake, epistemic uncertainties in probabilistic seismic hazard assessments have a significant effect on final results. Therefore, in order to mitigate earthquake disasters of dams, combination of probabilistic and deterministic methods should be applied for evaluating seismic hazards when large dams are constructed in strong seismicity regions.

Various flexible mechanisms related to quality of service (QoS) provisioning have been specified for uplink traffic at the medium access control (MAC) layer in the IEEE 802.16 standards. Among the mechanisms, contention based bandwidth request scheme can be used to indicate bandwidth demands to the base station for the non-real-time polling and best-effort services. These two services are used for most applications with unknown traffic characteristics. Due to the diverse QoS requirements of those applications, service differentiation (SD) is anticipated over the contention based bandwidth request scheme. In this paper we investigate the SD with the bandwidth request scheme by means of assigning different channel access parameters and bandwidth allocation priorities at different packets arrival probability. The effectiveness of the differentiation schemes is evaluated by simulations. It is observed that the initial backoff window can be efficient in SD, and if combined with the bandwidth allocation priority, the SD performances will be better.