Recent developments in both wireless communications and personal navigation technologies have made the concept of location-aware services both feasible and economical. Indeed, it is widely projected that the market for such services will increase substantially in the coming years. Obviously this market will provide significant opportunities and challenges for the tourism sector. In this article...

In a play about Galileo, Bertold Brecht has one of his characters comment bitterly after Galileo's recantation that "unhappy is a land that breeds no heroes." The reply by Galileo is "unhappy is a land that needs heroes." This exchange was brought to mind by David Hartmann's comments [1] on Ralph Nader's call for whistle blowinc engineers. Hartmann points out the risks incurred by any engineer ...

Abstract The stable operation of navigation satellite constellation is related to national economy and defense security. failure any one or two satellites has little impact on the overall performance global constellation, availability decreases with increase number failed satellites. First, a typical medium earth orbit Walker-δ 24/3/1 configuration was designed. Second, service under different ...

More and more Global Navigation Satellite Systems (GNSSs) have been developed and are in operation. Before integrating information on various GNSSs, the differences between the various systems must be studied first. This research focuses on analyzing the navigation data differences between the Chinese BeiDou Navigation Satellite System (BDS) and the United States' Global Positioning System (GPS...

This document describes a protocol for a Device to provide locationrelated measurement data to a Location Information Server (LIS) within a request for location information. Location-related measurement information provides observations concerning properties related to the position of a Device; this information could be data about network attachment or about the physical environment. A LIS is a...

This paper presents a genetic-based control scheme that not only utilizes evolutionary characteristics to find the signal acquisition parameters, but also employs an adaptive scheme to control the search space and avoid the genetic control converging to local optimal value so as to acquire the desired signal precisely and rapidly. Simulations and experiment results show that the proposed method...

This paper describes aspects of an information system being constructed for intelligent information retrieval in maritime navigation applications. The system is based largely on digital nautical charts, and the construction of a taxonomy of chart features and concepts related to the maritime navigation domain is described. This taxonomy is used in formulating queries and sub-queries for dispara...

This paper introduces a little-known episode in the history of physics, in which a mathematical proof by Pierre Fermat vindicated Galileo’s characterization of freefall. The first part of the paper reviews the historical context leading up to Fermat’s proof. The second part illustrates how a physical and a mathematical insight enabled Fermat’s result, and that a simple modification would satisf...