The border economy

The Texas border community has historically been the state's most disadvantaged area. However, the last decade has seen dramatic improvements in unemployment and other economic factors. This series of nine articles explores issues important to the region's economy—from job growth, wages and education to infrastructure demands, maquiladoras and illegal immigration.>Texas ; Employment (Economic theory) ; North American Free Trade Agreement

Orbiter-orbiter and orbiter-lander tracking using same-beam interferometry

Two spacecraft orbiting Mars will subtend a small angle as viewed from Earth. This angle will usually be smaller than the beam width of a single radio antenna. Thus the two spacecraft may be tracked simultaneously by a single Earth-based antenna. The same-beam interferometry (SBI) technique involves using two widely separated antennas, each observing the two spacecraft, to produce a measurement of the angular separation of the two spacecraft in the plane of the sky. The information content of SBI data is thus complementary to the line-of-sight information provided by conventional Doppler data. The inclusion of SBI data with the Doppler data in a joint orbit estimation procedure can desensitize the solution to gravity mismodeling and result in improved orbit determination accuracy. This article presents an overview of the SBI technique, a measurement error analysis, and an error covariance analysis of some examples of the application of SBI to orbit determination. For hypothetical scenarios involving the Mars Observer and the Russian Mars '94 spacecraft, orbit determination accuracy improvements of up to an order of magnitude are predicted, relative to the accuracy that can be obtained by using only Doppler data acquired separately from each spacecraft. Relative tracking between a Mars orbiter and a lander fixed on the surface of Mars is also studied. Results indicate that the lander location may be determined to a few meters, while the orbiter ephemeris may be determined with accuracy similar to the orbiter-orbiter case

A demonstration of high precision GPS orbit determination for geodetic applications

High precision orbit determination of Global Positioning System (GPS) satellites is a key requirement for GPS-based precise geodetic measurements and precise low-earth orbiter tracking, currently under study at JPL. Different strategies for orbit determination have been explored at JPL with data from a 1985 GPS field experiment. The most successful strategy uses multi-day arcs for orbit determination and includes fine tuning of spacecraft solar pressure coefficients and station zenith tropospheric delays using the GPS data. Average rms orbit repeatability values for 5 of the GPS satellites are 1.0, 1.2, and 1.7 m in altitude, cross-track, and down-track componenets when two independent 5-day fits are compared. Orbit predictions up to 24 hours outside the multi-day arcs agree within 4 m of independent solutions obtained with well tracked satellites in the prediction interval. Baseline repeatability improves with multi-day as compared to single-day arc orbit solutions. When tropospheric delay fluctuations are modeled with process noise, significant additional improvement in baseline repeatability is achieved. For a 246-km baseline, with 6-day arc solutions for GPS orbits, baseline repeatability is 2 parts in 100 million (0.4-0.6 cm) for east, north, and length components and 8 parts in 100 million for the vertical component. For 1314 and 1509 km baselines with the same orbits, baseline repeatability is 2 parts in 100 million for the north components (2-3 cm) and 4 parts in 100 million or better for east, length, and vertical components

Observation model and parameter partials for the JPL geodetic GPS modeling software GPSOMC

The physical models employed in GPSOMC and the modeling module of the GIPSY software system developed at JPL for analysis of geodetic Global Positioning Satellite (GPS) measurements are described. Details of the various contributions to range and phase observables are given, as well as the partial derivatives of the observed quantities with respect to model parameters. A glossary of parameters is provided to enable persons doing data analysis to identify quantities in the current report with their counterparts in the computer programs. There are no basic model revisions, with the exceptions of an improved ocean loading model and some new options for handling clock parametrization. Such misprints as were discovered were corrected. Further revisions include modeling improvements and assurances that the model description is in accord with the current software

Transportation infrastructure and the border economy

Trade ; Imports ; Exports ; Employment (Economic theory) ; North American Free Trade Agreement

The border: Is it really a low-wage area?

Employment (Economic theory)

The border economy; introduction

Texas ; Employment (Economic theory) ; North American Free Trade Agreement

Secondary education: its impact on border education

Employment (Economic theory)

The administration of small-scale economies in the cross- border trade in Southeast Asia

Purpose: This research aims to reveal that the servitude for economic interest in cross border trade zone can be applied in Southeast Asian countries. This trade cooperation includes the right to carry out certain actions in a country's territory as a place of trade for their foreign citizens. Approach/Methodology/Design: This study was conducted by using the field research and analyzed with descriptive analysis regarding the establishment of inter-state trade zones in the border regions of Malaysia and Indonesia. Findings: The results showed that managing the border region it is required to be emphasized by using servitude for economic interest to establish special trade zone for the creation of social justice in the border region. The establishment of a Special Area of Cross Border Trade, as that in Serikin market in Serawak, Malaysia, can be administratively used an alternative in managing the socio-economic border relations between Indonesia and Malaysia. There are several issues that must be examined as the implications of the establishment of border trade zones. Practical Implications: It is necessary to make an agreement on a special cross-border trade area to complement BCA and the BTA, in form of the Border Area Agreement (BAA). Originality/value: The trade area in the Serawak border is part of the acculturation of border communities, which requires special consideration in terms of management, legal rights and national jurisdiction. In addition, this kind of trade area is not formed by the Border Cross Agreement (BCA) and the Border Trade Agreement (BTA).peer-reviewe