A Comparison of Methods for Imposing Curvature on the Normalized Quadratic Indirect Profit Function

Research Methods/ Statistical Methods,

Fitting gravimetric geoid models to vertical deflections

Regional gravimetric geoid and quasigeoid models are now commonly fitted to GPS-levelling data, which simultaneously absorbs levelling, GPS and quasi/geoid errors due to their inseparability. We propose that independent vertical deflections are used instead, which are not affected by this inseparability problem. The formulation is set out for geoid slopes and changes in slopes. Application to 1080 astrogeodetic deflections over Australia for the AUSGeoid98 model shows that it is feasible, but the poor quality of the historical astrogeodetic deflections led to some unrealistic values

USING SATELLITE IMAGERY IN PREDICTING KANSAS FARMLAND VALUES

Can remotely sensed imagery improve hedonic land price models? A remotely sensed variable was added to a hedonic farmland value model as a proxy for land productivity. Land cover data were used to obtain urban and recreational effects as well. The urban and recreational effects were statistically significant but economically small. The remotely sensed productivity variable was statistically significant and economically large, indicating that knowing the "greenness" of the land increased the explanatory power of the hedonic price model. Thus, depending upon the cost of this information, including remotely sensed imagery in traditional hedonic land price models is economically beneficial.Land Economics/Use,

Property Tax Lids and the Effect on Kansas

Cross sectional time series data in a partial adjustment model examine local government behavior under an aggregate property tax levy limit and under Truth in Taxation in Kansas. Results indicate that the aggregate levy limit would have continued to restrict property tax revenue and spending had it not been replaced.Public Economics,

On the geodetic datums in Sri Lanka

The geodetic datums in Sri Lanka (formerly Ceylon) for latitude and longitude, height and gravity are described and discussed, because this information is not available in the open literature. It is recommended that most of these datums require some upgrading

Assessment of EGM2008 over Sri Lanka, an area where 'fill-in' data were used in EGM2008

The tide-free EGM2008 combined global geopotential model is compared with land and marine gravity observations and co-located GPS-levelling on and around Sri Lanka (formerly Ceylon). Not all these data are in the public domain, so offer an informative test of how the 'fill-in' methodology used in EGM2008 performs versus observed data. Sri Lanka is also in an area where the geoid exhibits its lowest elevation with respect to a geocentric reference ellipsoid. A -1.75 m bias between the GPS-levelling and EGM2008 led to an investigation into the Sri Lankan geodetic datums, showing a bias in the ellipsoidal heights. After rejection of 15 outliers, the standard deviation of the difference between 207 Sri Lankan GPS-levelling points and EGM2008 is 0.184 m. The difference between the gravity anomalies and EGM2008 showed that the Sri Lankan gravity data is based on the old Potsdam datum. The Sri Lankan land gravity data, after rejection of outliers, yielded standard deviations of 6.743 mGal for 20 GPS-coordinated gravity points on fundamental benchmarks, 14.704 mGal for 42 gravity points on fundamental benchmarks but with coarse locations, and 6.367 mGal for 1032 digitised and reconstructed free-air anomalies from a Bouguer anomaly map. The ship-track gravity data have not been crossover adjusted, and yield a standard deviation of 43.683 mGal. Importantly, the ability of EGM2008 to identify datum deficiencies is an implicit validation and leads to its applicationin other areas to search for datum deficiencies

Autonomous Real Time Architecture for High Performance Mobile Robots

Highly-dynamic robotic systems, such as hopping robots, require light, computationally and energy efficient on-board units for control. This paper presents such a computational unit together with a software architecture for achieving high-performance behaviors, such as balancing and hopping. These demanding behaviors require accurate dynamic calculations, high-bandwidth control, and fast real-time state estimation. The proposed system consists of cheap and off-the-shelf electronics that are detailed in this paper. The effectiveness of the presented approach is validated on a balancing machine called Tippy, which is able to achieve fast tracking of command signals while balancing. The experimental results of this paper demonstrate that reliable real-time software for demanding high-performance robotic applications, which require fast control loops and intensive calculations, can be achieved with light, low cost and energy efficient components, which can empower the widespread use and experimentation of high-performance robots worldwide

Recent Uses of Electron Microscopy in the Study of Physico-Chemical Processes Affecting the Reactivity of Synthetic and Biological Apatites

Studies which used scanning electron microscopy (SEM) to investigate subsurface demineralization of dental enamel have recently been well reviewed. The purpose of the present paper was to review several studies, carried out in our laboratories, which have used electron microscopy to examine physicochemical properties of synthetic and biological apatites, to relate these results to previous studies, and to present new data. Aspects of the ultrastructure of hydroxyapatite and carbonated-apatites have been observed by high resolution transmission electron microscopy, and related to shape and growth of these crystals. Surface morphologies of discs prepared from precipitated carbonated-apatites and from ceramic carbonated-apatites were examined by SEM and the information was used in the interpretation of apatite dissolution studies relevant to dental caries. Improvements in the technique of backscattered electron imaging of demineralized enamel have enabled better interpretation of enamel caries experiments. SEM examination of enamel and dentin treated by low energy lasers of specific wavelengths have shown that lasing conditions can be chosen that produce surface fusion of the apatite which inhibits caries-like lesion progression. SEM examination of crystals formed on and in enamel during high concentration fluoride treatments implies that calcium fluoride-like crystals are formed and they may act as a slow-release fluoride reservoir in the mouth

Predicting sea level variations with artificial neural networks at Hillarys Boat Harbour, Western Australia

In the present study, the artificial intelligence meshless methodology of neural networks was used to predict hourly sea level variations for the following 24 hours, as well as for half-daily, daily, 5-daily and 10-daily mean sea levels. The methodology is site specific; therefore, as an example, the measurements from a single tide gauge at Hillarys Boat Harbour, Western Australia, for the period December 1991-December 2002 were used to train and to validate the employed neural networks. The results obtained show the feasibility of the neural sea level forecasts in terms of the correlation coefficient (0.7-0.9), root mean square error (about 10% of tidal range) and scatter index (0.1-0.2)