http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/13685 2026-05-19T07:15:44Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/13849 Title: 63rd Annual Meeting of the Institute of Navigation 2007 Authors: [No author name available] Abstract: The proceedings contain 80 papers. The topics discussed include: the desert ant's navigational toolkit: procedural rather than positional knowledge; chemical plume tracking behavior in animals and mobile robots; how birds perceive and use compass information from the geomagnetic field; navigation of homing pigeons: an analysis of GPS-recorded tracks; historical review of atomic frequency standards used in satellite based navigation systems; the timing group delay (TGD) correction and GPS timing biases; benefits derived from laser ranging measurements for orbit determination of the GPS satellite orbit; sensor data analysis for a dual airborne laser scanner aided inertial navigator; geomagnetic navigation and magnetic maps in sea turtles; estimation and control of self-motion and gaze in flying insects; ionosphere effects for wideband GNSS signals; and validation of radio occultation retrieval methods for Canadian conditions. 2007-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/13848 Title: Power efficient vehicle detection algorithm using wireless magnetic sensor node Authors: Han B.; Huo H.; Chai K.; Zheng C.; Fang T.; Liu H. Abstract: A new vehicle detection algorithm, called the adaptive window distance (AWD) algorithm using magnetic wireless sensor node, is presented. The algorithm can detect the occurrence of the end point in the vehicle signal by calculating the signal feature distance between the background window and the current window and by separating vehicle-coming and vehicle-leaving events from geomagnetic background to realize vehicle detection. Moreover, based on the energy requirement in WSN application, This algorithm uses 'Duty-cycling' policy to decrease energy consuming of the sensor node. Experimental evaluation on dataset collected by Honeywell HMC1051Z and NVE GMR magnetometer is given. Compared with ATA, the detecting result of AWD shows that the algorithm has higher accuracy (97%), stronger robustness and better power efficiency. 2007-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/13847 Title: MF/HF/VHF radar observations of Polar Mesosphere Summer Echoes (PMSE) Authors: Ramos C.; Kelley M.C.; Djuth F.; Groves K.; Murayama Y. Abstract: PMSE, or Polar Mesosphere Summer Echoes, refers to a uniquely strong radar backscatter target that occurs during the summer season near the high latitude mesopause. The radar echoes are thought to be associated with noctilucent clouds (NLC), the highest clouds over the earth, due to the many similarities between both phenomena; e.g., altitude near the temperature minimum (mesopause region/85-km), seasonality, geographical location (northern and southern hemispheres), etc. An increased number of NLC sightings over the last century led to the suggestion that they are an indicator of climate change. Since the association of NLC with charged ice particles is now accepted as the source of PMSE, radar is the ideal observational technique to monitor long-term variations in the mesopause region and, possibly, the earth's atmospheric temperature. Lower temperatures in the upper mesosphere could be manifested in a larger number of NLC and PMSE events. Although PMSE have been well known since their discovery in the early eighties, the radar mechanism producing the echoes is not yet fully understood. Comparisons of VHF radar and rocket measurements during PMSE showed evidence of both turbulent and non-turbulent scattering mechanisms acting simultaneously or separately in the medium. The majority of the radar observations have been conducted at VHF/50 MHz, the reference sensors employed traditionally for PMSE studies; very few observations have been reported using radars operating at multiple frequencies. In an effort to extract new clues on this intriguing phenomenon, we conducted radar observations of PMSE at six different frequencies: 2.43, 4.53, 4.9, 28, 50, and 139 MHz, using radar facilities over the central Alaskan region. The echo morphology at the different frequencies is described in case studies wherein PMSE events were observed concurrently using at least two radar systems. The identity of MF and HF radar echoes as PMSE is resolved for the first time by means of simultaneous measurements made with VHF radars. On the basis of echo duration and signal strength, we suggest that HF radars would be optimal for PMSE monitoring. MF radars show highly organized PMSE layers quite often but are more susceptible to ionospheric absorption and higher altitude returns associated with geomagnetic activity. However, since a number of MF stations are located at polar or near polar latitudes, including Antarctica, it may be possible to use the PMSE signature studied here to investigate its long term variability as well as its low latitude boundary. The latter could be an indicator of global change and/or of lower temperatures in the earth's mesosphere, a necessary ingredient for NLC formation. © 2007 IEEE. 2007-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/13846 Title: Geomagnetic sensor based on giant magnetoelectric effect Authors: Zhai J.; Dong S.; Xing Z.; Li J.; Viehland D. Abstract: Here, the authors report a new type of geomagnetic field sensor based on the giant magnetoelectric effect in Metglas/piezoelectric-fiber laminates that are wrapped with a coil. These sensors can measure quite precisely the value of both the Earth's magnetic field and its inclination. The geomagnetic field sensor does not require a dc magnetic bias and is driven by a 10 mA ac. Highly sensitive dc magnetic field variations of less than 10-9 T and angular inclinations of ≤ 10-5 deg can be detected, potentially offering opportunities for a small global positioning device. © 2007 American Institute of Physics. 2007-01-01T00:00:00Z