| 1 | Characteristics of the Seismic Waves from a New Active Source Based on Methane Gaseous Detonation显示文摘Active seismic sources are critical for obtaining high resolution images of the subsurface.For active imaging in urban areas,environment friendly and green seismic sources are required.In present work,we introduce a new type of green active source based on the gaseous detonation of methane and oxygen.When fired in a closed container,the chemical reaction,i.e.gaseous detonation,will produce high pressure air over 150 MPa.Seismic waves are produced when high pressure air is quickly released to impact the surroundings.The first field experiment of this active source was carried out in December,2017 in Jingdezhen,Jiangxi Province,where a series of active sources were excited to explore their potential in mine exploration.In current work,we analyzed the seismic waves recorded by near-field accelerators and a dense short-period seismic array and compared them with those from a mobile airgun source,another kind of active source by releasing high pressure air into water.The results demonstrate that it can be used for high resolution near surface imaging.Firstly,the gaseous detonation productions are harmless CO2 and water,making it a green explosive source.Secondly,the dominant seismic frequencies are 10-80 Hz and a single shot can be recorded up to 15 km,making it suitable for local structure investigations.Thirdly,it can be excited in vertical wells,similar to traditional powder explosive sources.It can also act as an additional on-land active source to airgun sources,which requires a suitable water body as intermediate media to generate repeating signals.Moreover,the short duration and high frequency signature of the source signals make it safe with no damage to nearby buildings.These make it convenient to excite in urban areas.As a new explosive source,the excitation equipment and conditions,such as gas ratio,sink depth and air-releasing directions,need further investigation to improve seismic wave generation efficiency. | WANG Weitao WANG Xiang MENG Chuanmin DONG Shi WANG Zhigang XIE Junju WANG Baoshan YANG Wei XU Shanhui WANG Tao | 2019 | Earthquake Research in China2019，33，2： | 6 |
| 4 | The Establishment and Spatiotemporal History of A Novel HIV-1 CRF01_AE Lineage in Shenyang City, Northeastern China in 2002–2019显示文摘Dear Editor,In China,HIV-1 CRF01_AE has always been one of the most prevalent subtypes,especially among sexually active population,since it was initially reported in Yunnan and Guangxi Provinces during the early 1990s(Cheng et al.1994;Yu et al.1998;Chen et al.1999).Multiple independent introductions of CRF01_AE have led to the establishment of at least eight epidemic lineages in China,which have been circulating among different high-risk populations and have variable prevalence and geographic distribution(Li et al.2017). | Minghui An Wei Song Bin Zhao Xue Dong Lin Wang Wen Tian Xin Li Lu Wang Zhenxing Chu Junjue Xu Haibo Ding Xiaoxu Han Hong Shang | 2021 | Virologica Sinica2021，36，6： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员