scholarly journals Establishment of Geodetic Network in Nigeria

2019 ◽  
pp. 197-221
Author(s):  
Ikharo I. Blessing ◽  
Matthew N. Ono ◽  
Olaniyi Saheed S.
Keyword(s):  
Best Practices ◽  
Data Acquisition ◽  
Least Squares ◽  
Historical Development ◽  
Geodetic Network ◽  
Software Selection ◽  
Least Squares Adjustment ◽  
Selection For ◽  
Acquisition Method

This paper focus on the establishment of Geodetic Network in Nigeria which serve as the framework and basis for every spatially referenced system in the country. It explains the historical development of Nigeria geodetic network, its mode of establishment, data acquisition method, computation and adjustment principles. The use recent positioning satellites (GNSS) and its several methods were discussed with the Least Squares Adjustment techniques. Literatures on best practices were reviewed to identify gaps that need to be covered so as to have an accurate and efficient geodetic network in the Nigeria. The research is basically on principles and methodology on the establishment of Geodetic Network in Nigeria and silent on hardware and software selection for its establishment.

Lamb survival in relation to lambing and neonatal behaviour in medium wool Merino lines divergently selected for multiple rearing ability

1998 ◽  
Vol 38 (8) ◽  
pp. 801 ◽  
Author(s):  
S. W. P. Cloete ◽  
A. J. Scholtz
Keyword(s):  
Least Squares ◽  
Birth Rate ◽  
Time Lapse ◽  
Multiple Birth ◽  
Base Population ◽  
Merino Sheep ◽  
Litter Weight ◽  
Least Squares Adjustment ◽  
Selection For ◽  
Lamb Survival

Summary. Two lines of Merino sheep were divergently selected from the same base population since 1986 on maternal ranking values for multiple rearing ability. In the high (H) line, ewe and ram progeny were preferably descended from ewes that reared >1 lamb per joining. In the low (L) line, replacements were the progeny of ewes that reared <1 lamb per joining. Data on lamb mortality, lambing and neonatal behaviour as well as lamb production were obtained from these lines over 5 years (1993–97). Lamb survival was improved (P<0.01) in the H line, mainly as a result of the improved survival of multiples. It was evident that the survival of lambs was not compromised by selection for ewe multiple rearing ability, despite the fact that higher mortality levels are expected with an increase in multiple birth rate. No line difference was found for the time lapse from birth to first standing for >10 s, but H line lambs were quicker (P<0.01) to progress from standing to suckling than L line contemporaries (28 v. 38 min respectively). This line difference remained after adjustment for better co-operation of H line ewes with the first suckling attempts of their progeny. Ewes in the H line tended (P = 0.18) to remain longer on or near their birth sites than L line contemporaries (403 v. 362 min respectively). They also tended to be less (P = 0.07) likely to desert their lambs than L line ewes (12/424 = 0.028 v. 14/230 = 0.061 respectively). After least-squares adjustment for their heavier (P<0.01) litter weight, H line ewes experienced shorter (P<0.05) births than their L line contemporaries (46 v. 57 min respectively). Fewer (P<0.05) H line lambs died during or shortly after parturition (respective proportions of 22/890 = 0.025 and 25/441 = 0.057), while maiden H line ewes were less (P<0.05) likely to be assisted at lambing than L line contemporaries (4/107 = 0.037 v. 8/61 = 0.131 respectively). With regard to overall lamb production, it was found that the number of lambs weaned per ewe present at lambing in the H line was improved (P<0.05) in all years relative to that observed in the L line, the differences ranging from 25% in 1993 to 47% in 1997. Lamb weaning weight was correspondingly improved (P<0.05) in H line lambs, the differences ranging from 8% in 1994 to 22% in 1996. Fairly high levels of production could thus be attained with predominantly pasture-fed ewes selected for multiple rearing ability.

The Optimum Design of Geodetic Networks

1965 ◽  
Vol 19 (1) ◽  
pp. 90-91
Author(s):  
Michel Creusen ◽  
Harold J. Welch
Keyword(s):  
Computer Program ◽  
Least Squares ◽  
Optimum Design ◽  
Geodetic Network ◽  
University Of Michigan ◽  
Geodetic Networks ◽  
Least Squares Adjustment ◽  
The University

For a geodetic network, the least squares adjustment gives the best possible solution and an indication of the quality of that solution. On this basis, a computer program is being developed at the University of Michigan to determine the best and most economic configuration networks and the accuracies required in measuring.

scholarly journals Using Least-Squares Residuals to Assess the Stochasticity of Measurements—Example: Terrestrial Laser Scanner and Surface Modeling

2021 ◽  
Vol 5 (1) ◽  
pp. 59
Author(s):  
Gaël Kermarrec ◽  
Niklas Schild ◽  
Jan Hartmann
Keyword(s):  
Least Squares ◽  
Laser Scanner ◽  
Real Data ◽  
Point Clouds ◽  
Statistical Testing ◽  
Normal Vector ◽  
Engineering Structures ◽  
3D Point Clouds ◽  
Least Squares Adjustment ◽  
Correlation Parameters

Terrestrial laser scanners (TLS) capture a large number of 3D points rapidly, with high precision and spatial resolution. These scanners are used for applications as diverse as modeling architectural or engineering structures, but also high-resolution mapping of terrain. The noise of the observations cannot be assumed to be strictly corresponding to white noise: besides being heteroscedastic, correlations between observations are likely to appear due to the high scanning rate. Unfortunately, if the variance can sometimes be modeled based on physical or empirical considerations, the latter are more often neglected. Trustworthy knowledge is, however, mandatory to avoid the overestimation of the precision of the point cloud and, potentially, the non-detection of deformation between scans recorded at different epochs using statistical testing strategies. The TLS point clouds can be approximated with parametric surfaces, such as planes, using the Gauss–Helmert model, or the newly introduced T-splines surfaces. In both cases, the goal is to minimize the squared distance between the observations and the approximated surfaces in order to estimate parameters, such as normal vector or control points. In this contribution, we will show how the residuals of the surface approximation can be used to derive the correlation structure of the noise of the observations. We will estimate the correlation parameters using the Whittle maximum likelihood and use comparable simulations and real data to validate our methodology. Using the least-squares adjustment as a “filter of the geometry” paves the way for the determination of a correlation model for many sensors recording 3D point clouds.

Variable Selection for Partial Least-Squares Calibration of Near-Infrared Data from Orthogonally Designed Experiments

2002 ◽  
Vol 56 (3) ◽  
pp. 337-345 ◽  
Author(s):  
S. Kamaledin Setarehdan ◽  
John J. Soraghan ◽  
David Littlejohn ◽  
Daran A. Sadler
Keyword(s):  
Variable Selection ◽  
Least Squares ◽  
Partial Least Squares ◽  
Near Infrared ◽  
Designed Experiments ◽  
Selection For ◽  
Infrared Data

Network data acquisition method based on crop pest control knowledge

2021 ◽  
Author(s):  
Han Chunyu ◽  
Fang Jiandong ◽  
Li Bajin ◽  
Zhao Yudong
Keyword(s):  
Data Acquisition ◽  
Pest Control ◽  
Network Data ◽  
Crop Pest ◽  
Control Knowledge ◽  
Acquisition Method
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