How to tune graphene nanosheets (GNSs) with various morphologies has been a significant challenge for lithium ion batteries (LIBs). In this study, three types of GNSs with varying size, edge sites, defects and layer numbers have been successfully achieved. It was demonstrated that controlling GNS morphology and microstructure has important effects on its cyclic performance and rate capability i...

The viscosity of polydispersed graphene nanosheet (5 nm–1.5 lm) suspensions (GNS) and its behavior with temperature and concentration have been experimentally determined. A physical mechanism for the enhanced viscosity over the base fluids has been proposed for the polydispersed GNSs. Experimental data reveal that enhancement of viscosity for GNSs lies in between those of carbon nanotube suspen...

The Global Navigation Satellite System (GNSS) plays an important role in positioning and navigation applications. The Global Positioning Service (GPS) augmentation is to achieve more reliable and accurate navigation solutions. The presently available traditional GNSS receivers are hardware based receivers which are not flexible and cannot be easily upgraded to acquire the signals from other GNS...

GNSS augmentation systems that provide integrity guarantees to users typically assume that all GNSS satellites have the same failure probability. The assumed failure probability is conservative such that variations among satellites in a given GNSS constellation are not expected to violate this assumption. A study of unscheduled GPS satellite outages from 1999 to present shows that, as expected,...

This paper addresses the problem of modeling and simulating RF-signals captured by receivers of Global Navigation Satellite Systems (GNSS) in urban canyons. The presence of tall buildings in urban canyons often block lines of sight between receivers and GNSS satellites, and therefore signals reach the receivers indirectly, after bouncing off buildings. These multi-path and echo-only effects are...

The signals that are available for navigation depend on the environment. To operate reliably in a wide range of different environments, a navigation system is required to adopt different techniques based on the environmental contexts. In this paper, an environmental context detection framework is proposed, building the foundation of a context adaptive navigation system. Different land environme...

The growing market of GNSS capable mobile devices is driving the interest of GNSS software solutions, as they can share many system resources (processor, memory), reducing both the size and the cost of their integration. Indeed, with the increasing performance of modern processors, it becomes now feasible to implement in software a multichannel GNSS receiver operating in real time. However, a m...

Marc-Antoine Fortin is currently pursuing his Ph.D. in the field of GNSS receivers’ robustness at École de technologie supérieure (ÉTS) in Montréal, Canada. He previously received an Electrical Engineering Master’s degree from École Polytechnique de Montréal (Canada) in 2005 and a Bachelor’s degree in the same field from Université de Sherbrooke in 2003 (Canada). He is interested in new methods...

Galileo is the program that has been launched by the European Union for the purpose of building a Global Navigation Satellite System (GNSS) for serving civilians and to exist under civil control. Our project combines many previous researched scenarios for Galileo system to a final one, which has been simulated and adjusted to meet the most demanding standards (of proposed GNSS services). The fi...

Grace Xingxin Gao is a research associate in the GPS lab of Stanford University. She received the B.S. degree in mechanical engineering and the M.S. degree in electrical engineering, both at Tsinghua University, Beijing, China. She obtained the Ph.D. degree in electrical engineering at Stanford University. Her current research interests include GNSS signal and code structures, GNSS receiver arc...