S/A Selective Availability. Deliberate degradation of GPS signal by U.S. Department of Defense. The practice was discontinued in May 2000. GPS coordinates were expected to be accurate within 100 m with S/A turned on, and about 10 m with S/A off. DGPS improves accuracy in either case.

Problems of planar covering with ellipses are tackled in this work. Ellipses can have a fixed angle or each of them can be freely rotated. Deterministic global optimization methods are developed for both cases, while a stochastic version of the method is also proposed for large instances of the latter case. Numerical results show the effectiveness and efficiency of the proposed methods.

Existing apriori tropospheric models are not sufficiently accurate to remove tropospheric delay from GPS observations. Remaining effects of residual tropospheric delay need to be estimated to ensure high accuracy and reliability of GPS positioning. Other researchers have shown that implementations of network-based positioning techniques can adequately model the residual tropospheric delay as we...

the global health agenda has been dominating the current global health policy debate. furthermore, it has compelled countries to embrace strategies for tackling health inequalities in a wide range of public health areas. the article by robert and colleagues highlights that although globalization has increased opportunities to share and spread ideas, there is still great asymmetry of power accor...

Accurate estimation of construction production, which is composed of productivity and unit costs, allows construction planners and managers to have excellent control over current processes and to correctly predict the production of similar projects in the future. Due to the need for accurate production estimation, selection of the appropriate construction technology is a critical factor in the ...

ecological footprint analysis in agriculture is a new and evolving subject. the main purpose of the study was to assess environmental sustainability of conventional and conservation tillage systems using ecological footprint analysis in hamedan province. global hectares (gha) were used to measure the ecological footprint unit. data was collected through questionnaires and use of cross-sectional...

Forced migration has become a world-wide phenomenon in the past century, affecting increasing numbers of countries and people. It entails important challenges from a global health perspective. Leppold et al have critically discussed the Japanese interpretation of global responsibility for health in the context of forced migration. This commentary complements their analysis by outlining three pr...

Differential global surface impedance (DGSI) model, a rigorous approach, has been applied to the analysis of three dimensional plasmonic circuits. This model gives a global relation between the tangential electric field and the equivalent surface electric current on the boundary of an object. This approach helps one bring the unknowns to the boundary surface of an object and so avoid volumetric...