An approach to aid INS using time-differenced GPS carrier phase (TDCP) measurements

This paper presents a simple and effective approach that incorporates single-frequency, L1 time-differenced GPS carrier phase (TDCP) measurements without the need of ambiguity resolution techniques and the complexity to accommodate the delayed-state terms. Static trial results are included to illustrate the stochastic characteristics and effectiveness of the TDCP measurements in controlling position error growth. The formulation of the TDCP observation model is also described in a 17-state tightly-coupled GPS/INS iterative, extended Kalman filter (IEKF) approach. Preliminary land vehicle trial results are also presented to illustrate the effectiveness of the TDCP which provides sub-meter positional accuracies when operating for more than 10 min.     

Revolution or evolution? New Zealand agriculture since 1984

Agriculture was the primary target of moves to deregulate the New Zealand economy in 1984. Within twelve-months all production subsidies had been removed, including those for fertiliser and other inputs, as well as funding for drought relief, floods and other natural weather disasters. Whereas at the start of 1984, subsidies were estimated to represent as much as 33% of farm income, by 2003 this had fallen to less than 2% with most of this spent on agricultural research. The anticipated shift of thousands of people off the land did not appear to occur, and by conventional measures at least New Zealand agriculture in 2003 is a major success story. At the core of the changes imposed on agriculture was a commitment to remove all state or government distortions from the system and to fully expose the agricultural sector to market forces. This included wide-ranging and fundamental changes in the broad institutional context within which agriculture must operate. All this was achieved at great social cost and with a significant impact on the environment. In many respects New Zealand agriculture is now very different from that in 1984. Some sectors, such as dairying, have grown and become increasingly industrialised. On the other hand, sheep farming, particularly for wool has struggled to maintain its market share, while other enterprises have emerged as significant sources of income, including horticulture, viticulture and fruit. It is argued here that the trends evident in New Zealand agriculture since 1984 pre-existed the reform period and that the apparent success of the reforms evident at a national scale have not addressed or removed the fundamental problems which face New Zealand agriculture, just as they do modern agricultural systems elsewhere. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Public Is Intellectual

This article is a discussion and critique of public intellectualism in the present. Rather than reify a self-aggrandized form of public intellectualism within academia that centers individualized intellectual development and that encourages a greater flow of findings outward to communities, I highlight black women public intellectuals who have used their skills, talents, and station within the university and society in novel ways. Moreover, I suggest that scholars take seriously the questions, research methods, and analyses emerging from the general public, particularly from within communal and political organizations. These encouragements are illustrated by highlighting three political education workshops that have been developed across the United States.     

International Mineralogical Association (IMA)

International Mineralogical Association (IMA)15th General Meeting, Beijing, China, June 28–July 3, 1990     

Simulation of the extreme waves generated by typhoon Bolaven (1215) in the East China Sea and Yellow Sea

Record-breaking high waves occurred during the passage of the typhoon Bolaven (1215) (TYB) in the East China Sea (ECS) and Yellow Sea (YS) although its intensity did not reach the level of a super typhoon. Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys. In order to understand how such high waves with long duration occurred, analyses have been made through measurement and numerical simulations. TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements. And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model. Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area. Thus the accuracy of simulations is considerably enhanced, and the computed results are also in better agreement with measured data than before. It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track. As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days, the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.     

Differential rotation of some HK-Project stars and the butterfly diagrams

We analyze the long-term variability of the chromospheric radiation of 20 stars monitored in the course of the HK-Project at the Mount Wilson Observatory. We apply the modified wavelet algorithm for this set of gapped time series. Besides the mean rotational periods for all these stars, we find reliable changes of the rotational periods from year to year for a few stars. Epochs of slower rotation occur when the activity level of the star is high, and the relationship repeats again during the next maximum of an activity cycle. Such an effect is traced in two stars with activity cycles that are not perfectly regular (but labeled “Good” under the classification in [Baliunas, S.L., Donahue, R.A., Soon, W.H., Horne, J.H., Frazer, J., Woodard-Eklund, L., Bradford, M., Rao, L.M., Wilson, O.C., Zhang, Q. et al., 1995. ApJ 438, 269.]) but the two stars have mean activity levels exceed that of the Sun. The averaged rotational period of HD 115404 is 18.5 days but sometimes the period increases up to 21.5 days. The sign of the differential rotation is the same as the Sun’s, and the value ΔΩ/Ω=-0.14. For the star HD 149661, this ratio is −0.074. Characteristic changes of rotational periods occur over around three years when the amplitude of the rotational modulation is large. These changes can be transformed into latitude-time butterfly diagrams with minimal a priori assumptions. We compare these results with those for the Sun as a star and conclude that epochs when surface inhomogeneities rotate slower are synchronous with the reversal of the global magnetic dipole.     

SPH modeling of tidal bore scenarios

Natural Hazards - The paper presented a smoothed particle hydrodynamics (SPH) method to study the three-dimensional (3D) tidal bore scenarios. The SPH method is a mesh-free particle modeling...