Flexible monolithic ultra-portable ground penetrating radar using inkjet printing technology

Flexible monolithic ultra-portable ground penetrating radar using inkjet printing technology A Ground Penetrating Radar (GPR) performs nondestructive detection of buried objects, or subsurface imaging by transmitting electromagnetic waves and detecting and analyzing the reflections. The main challenge of GPR is the reduction in detection range due to the severe signal attenuation that is caused by subsurface conductivity that becomes more severe at high frequencies. In order to increase the detection range, GPR uses lower frequencies than non-GPR radars and thus requires larger antennas that may limit system portability. Most GPR systems use impulse radars however the FMCW (frequency modulated continuous wave) radar can provide some advantages such as frequency versatility, reduced system maintenance and improved range resolution. Frequencies below 1 GHz were initially uncommon in short-range FMCW radars but are now finding their way back in systems such as ultra-wideband (UWB) ground penetrating radars for mine detection and as well as other applications. When measurements are performed on vehicles, large antenna fixtures are not a problem. Portability, however, can become an issue in geophysical studies or emergency work in which one may need to transport the system through rugged, unexplored and/or hazardous locations without vehicle access and perform measurements. Inaccessible environments may require climbing up and down, squeezing through, jumping over, crawling under, maneuvering through or swimming through obstacles (mountains, caves, lakes, rocky areas). In addition to transportation, rapid system setup is critical in difficult conditions such as freezing temperatures or extreme heat where exposure time is costly and limits measurement time. One solution to enhance the portability and deployability of a GPR system for wide area rugged measurements is to realize a complete system on a continuous substrate that is rollable around a reasonably small radius and storable in a scroll or poster-like fashion for easy backpack transportation. Electronics that can flex and bend have already used in military applications and for outdoor sporting gear. Currently, there are a few types of technology available to realize flexible electronics that have been a major topic of research, each with different levels of integration. Inkjet printing technology offers a cost effective, versatile and efficient method for realizing flexible devices. In this work a classical FMCW radar system is designed and an effort is made, for the first time, to apply inkjet printing technology to a radar system. The system is referred to as a portable monolithic radar system in which all actives, passives and antenna are meant to share the same continuous rollable substrate. In doing this, a medium level of integration is used to investigate limits of system complexity, resolution and ultra miniaturization for tight rollability. Various design challenges of a large system are overcome that will hopefully give insight to new designs as the integration level using inkjet printing technology increases

Effect of a Terminal Overdeepening on Glacier Hydrology and Flow

Overdeepenings in the bedrock topography beneath glaciers are commonplace. Despite this, the subglacial processes associated with them remain poorly understood. It has been hypothesized that adverse bed gradients can reduce the efficiency of the drainage system and therefore encourage basal sediment to accumulate. To determine to what extent an overdeepening might influence ice flow and the drainage system, a terminal overdeepening at Findelengletscher, Switzerland was targeted. 9 Unmanned Aerial Vehicle (UAV) surveys were carried out, spread across late August and early September 2016, early July 2017 and early September 2017 along with two Ground Penetrating Surveys (GPR) in February and July 2017. An overdeepening with a bed to surface slope ratio above the threshold for glaciohydraulic supercooling with basal sediment layers on its adverse slope was present. Up-glacier Ice flow velocities and spatial ice loss patterns across the meltseason were consistent with drainage system evolution, whilst a less efficient system was present longer at the overdeepening. Findings indicate that drainage, and thus ice flow, at the terminus of Findelengletscher are strongly influenced by the adverse slope. The presence of a more inefficient distributed system at the terminus leads to a reduction in energy also decreases water velocity and, with it, sedimental transport in this location leading to evidence of englacial thrusting at the terminus. It is recommended that bed topography be given consideration when considering rates of sediment erosion and transportation