Dual Farrell measures of efficiency

This paper is a revised version of an old 1982 paper by the author, partially published in Spanish as Muro and Vera (1983) and cited for example in Fare (1985). The usual disclaimer appliesThis paper provides several definitions of efficiency measures in the price space. Economic and scale aspects of inefficiency are considered to give empirical content to the measurement of efficiency when the production technology is described by cost functions models. It shows, in the Hanoch’s symmetric duality approach, how the new definitions preserve the ranking of efficiency, are formally dually symmetric to the ones defined in the input space, and both are established with respect to different descriptions of the same technology. In addition, graphical procedures are utilized to make an insight into the achievement of polar technologies from primal ones and into the relationship between Shephard’s lemma and Roy’s identity

A comprehensive analysis of the geometry of TDOA maps in localisation problems

In this manuscript we consider the well-established problem of TDOA-based source localization and propose a comprehensive analysis of its solutions for arbitrary sensor measurements and placements. More specifically, we define the TDOA map from the physical space of source locations to the space of range measurements (TDOAs), in the specific case of three receivers in 2D space. We then study the identifiability of the model, giving a complete analytical characterization of the image of this map and its invertibility. This analysis has been conducted in a completely mathematical fashion, using many different tools which make it valid for every sensor configuration. These results are the first step towards the solution of more general problems involving, for example, a larger number of sensors, uncertainty in their placement, or lack of synchronization.Comment: 51 pages (3 appendices of 12 pages), 12 figure

The Helicopter Antenna Radiation Prediction Code (HARP)

The first nine months effort in the development of a user oriented computer code, referred to as the HARP code, for analyzing the radiation from helicopter antennas is described. The HARP code uses modern computer graphics to aid in the description and display of the helicopter geometry. At low frequencies the helicopter is modeled by polygonal plates, and the method of moments is used to compute the desired patterns. At high frequencies the helicopter is modeled by a composite ellipsoid and flat plates, and computations are made using the geometrical theory of diffraction. The HARP code will provide a user friendly interface, employing modern computer graphics, to aid the user to describe the helicopter geometry, select the method of computation, construct the desired high or low frequency model, and display the results

Investigations of 5G localization with positioning reference signals

TDOA is an user-assisted or network-assisted technique, in which the user equipment calculates the time of arrival of precise positioning reference signals conveyed by mobile base stations and provides information about the measured time of arrival estimates in the direction of the position server. Using multilateration grounded on the TDOA measurements of the PRS received from at least three base stations and known location of these base stations, the location server determines the position of the user equipment. Different types of factors are responsible for the positioning accuracy in TDOA method, such as the sample rate, the bandwidth, network deployment, the properties of PRS, signal propagation condition, etc. About 50 meters positioning is good for the 4G/LTE users, whereas 5G requires an accuracy less than a meter for outdoor and indoor users. Noteworthy improvements in positioning accuracy can be achievable with the help of redesigning the PRS in 5G technology. The accuracy for the localization has been studied for different sampling rates along with different algorithms. High accuracy TDOA with 5G positioning reference signal (PRS) for sample rate and bandwidth hasn’t been taken into consideration yet. The key goal of the thesis is to compare and assess the impact of different sampling rates and different bandwidths of PRS on the 5G positioning accuracy. By performing analysis with variable bandwidths of PRS in resource blocks and comparing all the analyses with different bandwidths of PRS in resource blocks, it is undeniable that there is a meaningful decrease in the RMSE and significant growth in the SNR. The higher bandwidth of PRS in resource blocks brings higher SNR while the RMSE of positioning errors also decreases with higher bandwidth. Also, the number of PRS in resource blocks provides lower SNR with higher RMSE values. The analysis with different bandwidths of PRS in resource blocks reveals keeping the RMSE value lower than a meter each time with different statistics is a positivity of the research. The positioning accuracy also analyzed with different sample sizes. With an increased sample size, a decrease in the root mean square error and a crucial increase in the SNR was observed. From this thesis investigation, it is inevitable to accomplish that two different analyses (sample size and bandwidth) done in a different way with the targeted output. A bandwidth of 38.4 MHz and sample size N = 700 required to achieve below 1m accuracy with SNR of 47.04 dB

Seismic Applications of Interactive Computational Methods

Effective interactive computing methods are needed in a number of specific areas of geophysical interpretation, even though the basic algorithms have been established. One approach to raise the quality of interpretation is to promote better interaction between human and the computer. The thesis is concerned with improving this dialog in three areas: automatic event picking, data visualization and sparse data imaging. Fully automatic seismic event picking methods work well in relatively good conditions. They collapse when the signal-to-noise ratio is low and the structure of the subsurface is complex. The interactive seismic event picking system described here blends the interpreter's guidance and judgment into the computer program, as it can bring the user into the loop to make subjective decisions when the picking problem is complicated. Several interactive approaches for 2-D event picking and 3-D horizon tracking have been developed. Envelope (or amplitude) threshold detection for first break picking is based on the assumption that the power of the signal is larger than that of the noise. Correlation and instantaneous phase pickers are designed for and better suited to picking other arrivals. The former is based on the cross-correlation function, and a model trace (or model traces) selected by the interpreter is needed. The instantaneous phase picker is designed to track spatial variations in the instantaneous phase of the analytic form of the arrival. The picking options implemented into the software package SeisWin were tested on real data drawn from many sources, such as full waveform sonic borehole logs, seismic reflection surveys and borehole radar profiles, as well as seven of the most recent 3-D seismic surveys conducted over Australian coal mines. The results show that the interactive picking system in SeisWin is efficient and tolerant. The 3-D horizon tracking method developed especially attracts industrial users. The visualization of data is also a part of the study, as picking accuracy, and indeed the whole of seismic interpretation depends largely on the quality of the final display. The display is often the only window through which an interpreter can see the earth's substructures. Display is a non-linear operation. Adjustments made to meet display deficiencies such as automatic gain control (AGC) have an important and yet ill-documented effect on the performance of pattern recognition operators, both human and computational. AGC is usually implemented in one dimension. Some of the tools in wide spread use for two dimensional image processing which are of great value in the local gain control of conventional seismic sections such as edge detectors, histogram equalisers, high-pass filters, shaded relief are discussed. Examples are presented to show the relative effectiveness of various display options. Conventional migration requires dense arrays with uniform coverage and uniform illumination of targets. There are, however, many instances in which these ideals can not be approached. Event migration and common tangent plane stacking procedures were developed especially for sparse data sets as a part of the research effort underlying this thesis. Picked-event migration migrates the line between any two points on different traces on the time section to the base map. The interplay between the space and time domain gives the interpreter an immediate view of mapping. Tangent plane migration maps the reflector by accumulating the energy from any two possible reflecting points along the common tangent lines on the space plane. These methods have been applied to both seismic and borehole-radar data and satisfactory results have been achieved

Seismic Applications of Interactive Computational Methods

Effective interactive computing methods are needed in a number of specific areas of geophysical interpretation, even though the basic algorithms have been established. One approach to raise the quality of interpretation is to promote better interaction between human and the computer. The thesis is concerned with improving this dialog in three areas: automatic event picking, data visualization and sparse data imaging. Fully automatic seismic event picking methods work well in relatively good conditions. They collapse when the signal-to-noise ratio is low and the structure of the subsurface is complex. The interactive seismic event picking system described here blends the interpreter's guidance and judgment into the computer program, as it can bring the user into the loop to make subjective decisions when the picking problem is complicated. Several interactive approaches for 2-D event picking and 3-D horizon tracking have been developed. Envelope (or amplitude) threshold detection for first break picking is based on the assumption that the power of the signal is larger than that of the noise. Correlation and instantaneous phase pickers are designed for and better suited to picking other arrivals. The former is based on the cross-correlation function, and a model trace (or model traces) selected by the interpreter is needed. The instantaneous phase picker is designed to track spatial variations in the instantaneous phase of the analytic form of the arrival. The picking options implemented into the software package SeisWin were tested on real data drawn from many sources, such as full waveform sonic borehole logs, seismic reflection surveys and borehole radar profiles, as well as seven of the most recent 3-D seismic surveys conducted over Australian coal mines. The results show that the interactive picking system in SeisWin is efficient and tolerant. The 3-D horizon tracking method developed especially attracts industrial users. The visualization of data is also a part of the study, as picking accuracy, and indeed the whole of seismic interpretation depends largely on the quality of the final display. The display is often the only window through which an interpreter can see the earth's substructures. Display is a non-linear operation. Adjustments made to meet display deficiencies such as automatic gain control (AGC) have an important and yet ill-documented effect on the performance of pattern recognition operators, both human and computational. AGC is usually implemented in one dimension. Some of the tools in wide spread use for two dimensional image processing which are of great value in the local gain control of conventional seismic sections such as edge detectors, histogram equalisers, high-pass filters, shaded relief are discussed. Examples are presented to show the relative effectiveness of various display options. Conventional migration requires dense arrays with uniform coverage and uniform illumination of targets. There are, however, many instances in which these ideals can not be approached. Event migration and common tangent plane stacking procedures were developed especially for sparse data sets as a part of the research effort underlying this thesis. Picked-event migration migrates the line between any two points on different traces on the time section to the base map. The interplay between the space and time domain gives the interpreter an immediate view of mapping. Tangent plane migration maps the reflector by accumulating the energy from any two possible reflecting points along the common tangent lines on the space plane. These methods have been applied to both seismic and borehole-radar data and satisfactory results have been achieved

A fast approach for perceptually-based fitting strokes into elliptical arcs

Fitting elliptical arcs to strokes of an input sketch is discussed. We describe an approach which automatically combines existing algorithms to get a balance of speed and precision. For measuring precision, we introduce fast metrics which are based on perceptual criteria and are tolerant of sketching imperfections. We return a likelihood estimate based on these metrics rather than deterministic yes/no result, in order that the approach can be used in higher-level collaborative-decision recognition flows.1) Ramon y Cajal Scholarship Programme 2) "Pla de Promoció de la Investigació de la Universitat Jaume I", project P1 1B2010-0

UV-Diagram: A Voronoi Diagram for Uncertain Spatial Databases

published_or_final_versio

Ground penetrating radar investigations in Upper Kama potash mines

An understanding of the structure and state of the rock mass surrounding underground openings in the potash mines is critically important for safe mining, planning the methods of extraction of an orebody, and preventing the influx of ground water. Continuous common offset ground penetrating radar (GPR) data were acquired in the potash mine operated by the Joint Stock Company (JSC) Silvinit (Russia) as part of an investigation of both pre-existing fractures exposed by mine workings and other anomalous geological structures. During the course of GPR investigation, the electrical properties of salt-bearing units were determined, site-specific data acquisition techniques and object-oriented data processing schemes adapted to the geological and geotechnical environment of the Upper Kama potash deposit were developed, and the methodology of 2-D and 3-D GPR data interpretation using interactive modeling was worked out. Open fractures and fault and fold features were successfully mapped using 2-D and 3-D GPR techniques. FK filtering significantly improved the reliability of fracture detection. Spatial models of mapped fractures were created using 3-D GPR imaging technique. Migration of the georadar data was required to obtain the true geometry of folded salt beds. The results of this GPR-based investigation demonstrate that the ground penetrating radar georadar method is capable of providing valuable information about deformation structures within the evaporite units of the Upper Kama potash deposit --Abstract, page iv