Permafrost environment monitoring on the Qinghai-Tibet Plateau using time series ASAR images

The permafrost in Qinghai-Tibet Plateau(QTP)has long been the focus of many researchers.In this study,we first use the method that integrates synthetic aperture radar(SAR)intensity and phase information to monitor permafrost environment in the Beiluhe Region,using time series advanced SAR images.The backscattering coefficients(σ^(0))and deformation were extracted for the main features,and the influences of meteorological conditions to them were also quantified.The results show that both the change inσ^(0)and surface deformation are closely related to the active layer,and the deformation is also affected by the permafrost table.First,over meadow and sparse vegetation regions,σ^(0)rose about 6.9 and 4 dB from the freezing to thawing period,respectively,which can be mainly attributed to the thaw of the active layer and increased precipitation.Second,seasonal deformation,derived from the freeze-thaw cycle of the active layer,was characteristic of frost heave and thaw settlement and exhibited a negative correlation with air temperature.Its magnitude was larger than 1 cm in a seasonal cycle.Last,significant secular settlement was observed,with rates ranging from-16 to 2 mm/a,and it was primarily due to the thaw of the permafrost table caused by climate warming.

UAV Laser scanning technology:a potential cost-effective tool for micro-topography detection over wooded areas for archaeological prospection

Airborne laser scanning(ALS)has recently been identified as a potential tool in topographic mapping for archaeological prospection.However,most existing applications in this field refers to manned ALS systems,for which the high operation and maintenance costs limits its application in small-scale archaeological investigation.In this paper,we conducted an exploratory study on the application of the unmanned aerial vehicle(UAV)laser scanning(ULS)system in ancient micro-topography detection over wooded areas.Compared with manned ALS technology,we analyzed the advantages and potentials of ULS technology for archaeological applications.Then we outlined existing mainstream survey-grade UAV-based laser scanners,data processing and visualization approaches.Furthermore,we performed case studies in three cultural heritage sites in Zhejiang Province,China using two representative mainstream survey-grade ULS systems.Results were then verified by an in-site investigation.Finally,the correct selection of ULS devices,the planning of data acquisition missions and the use of appropriate data processing methods specifically for archaeological prospection were discussed.This paper provides a cost-effective and flexible solution for micro-topography detection in wooded areas.ULS technology,as demonstrated here,can be an important supplement to existing archaeological investigation methods,particularly for small-scale areas,and has promising prospects in archaeological applications.

Archeological crop marks identified from Cosmo-SkyMed time series: the case of Han-Wei capital city, Luoyang, China

The development of spaceborne Synthetic Aperture Radar(SAR)technology declares that the golden era of SAR remote sensing in archeology is approaching;however,nowadays its methodology framework is still lacking due to the inadequate case studies validated by ground-truths.In this study,we investigated the crop marks using multi-temporal Cosmo-SkyMed data acquired in 2013 by applying a twostep decision-tree classifier in conjunction with a spatial analysis in an area of archeological interest nearby the archeological site of Han-Wei capital city(1900–1500 BP),in Luoyang,China.The time-series backscattering anomalies related to the wheat growth cycle were identified and then further validated in two zones by geophysical investigations(Ground Penetration Radar and electrical measurements)and in a third zone by archeological excavations made after the SAR data acquisition.This study provides a new approach for the relic detection,shallowly buried and covered by the crop vegetation,by temporal crop marks on spaceborne SAR images.We also emphasize the necessity to establish a satellite-to-ground methodology framework for the promotion of remote-sensing technology in archeology.

Investigation of the on-state behaviors of the variation of lateral width LDMOS device by simulation

In this paper, the main content revolves round the on-state characteristics of the variation of a lateral width(VLW) LDMOS device. A three-dimensional numerical analysis is performed to investigate the specific onresistance of the VLW LDMOS device, the simulation results are in good agreement with the analytical calculation results combined with device dimensions. This provides a theoretical basis for the design of devices in the future. Then the self-heating effect of the VLW structure with a silicon-on-oxide(SOI) substrate is compared with that of a silicon carbide(SiC) substrate by 3 D thermoelectric simulation. The electrical characteristic and temperature distribution indicate that taking into account the SiC as the substrate can mitigate the self-heating penalty effectively, alleviating the self heating effect and improving reliability.