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La inversión en cualquier economía constituye uno de los pilares en la senda del crecimiento económico. En el Perú, su evolución ha tenido un comportamiento cíclico a través del tiempo, afectando el crecimiento económico y el bienestar de su población. Así, surge la inquietud de elaborar una investigación que permita analizar las características del comportamiento de la inversión en el Perú durante los últimos años para comprender los problemas que dificultan su sostenibilidad en el tiempo y así diseñar una estrategia que permita su constancia como variable fundamental del crecimiento económico. Por ello, el objetivo de la presente investigación es analizar los factores determinantes que influyen en la dinámica de la inversión peruana en el período 1980 – 2006. Para cumplir con el objetivo, se ha dividido el trabajo de investigación en cinco capítulos. El primer capítulo trata sobre los procesos y modelos de desarrollo aplicados en el Perú, especialmente a partir de 1980. En esta parte se estudiará cómo las corrientes económicas en cada período de gobierno influenciaron en la conducción de la política económica y el rol que jugó la inversión en dicho proceso. En el segundo capítulo se analiza el comportamiento y la importancia del ahorro interno y del ahorro externo como fuentes de financiamiento de la inversión privada. Asimismo, se hace un breve análisis del impacto de la reforma financiera en el ahorro privado, como mecanismo de financiamiento para la inversión. En el tercer capítulo se estudia el marco jurídico vigente para la inversión privada y para la inversión extranjera. Además, se analiza el papel de las reformas realizadas en materia tributaria, arancelaria y laboral para hacer más atractivo al país como foco de inversiones. Finalmente, se estudia la importancia de dos calificaciones internacionales como lo son el Riesgo País y el Grado de Inversión en la ejecución de proyectos de inversión de gran envergadura. En el cuarto capítulo se estudia el comportamiento de la inversión pública en infraestructura y la relación que existe entre la inversión en infraestructura y el crecimiento económico, generación de empleo y la reducción de la pobreza, así como la influencia de la inversión privada a través de las concesiones y privatizaciones. Finalmente, en el quinto capítulo se propone una estrategia para asegurar el incremento de la inversión, especialmente la inversión privada nacional y extranjera que permita al país salir de la pobreza y de la pobreza extrema.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy / Inverse theory provides an important tool that the geophysicist can use to explore the structure of the Earth. This thesis examines several new approaches to the inverse problem, and suggests ways of improving the conventional least-squares technique. Non least-squares inversion was applied to borehole temperature data from South Africa, and when the norm of the inversion was controlled by the statistics of the misfit, It reduced by over 50% the number of iterations required for the inversion to converge upon a solution. Various damping schemes were also examined, and the use of the misfit in controlling the damping is shown to provide the best solution of those studied (Cooper and Jones, in press). Improvements to the efficiency of the inverse process were also achieved by the fitting of parabolic forms to portions of the misfit surface, using both the misfit value and the gradient of the surface. for gravity data. The presence of nearby minima other than the one that the inversion has just converged to can also be detected in this manner. The set of initial models that converged to a particular solution using leastsquares inversion was studied for magnetic data, and it was noted to have a fractal nature. The fractal dimension of the set was found to be inversely proportional to the damping of the inverse problem. The inverse process was pushed into a chaotic state by the modification of the least-squares inversion equation. The chaotic state was studied, and exploited to / AC2017

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In most cases of seismic processing and interpretation, elastic isotropy is assumed. However, velocity anisotropy is found to exist in most subsurface media. Hence, there exists a fundamental inconsistency between theory on the one hand, and practice on the other. If not recognised, this can invalidate interpretation of seismic data. In this thesis, inversion methods for elastic parameters are developed to quantify the degree of velocity anisotropy of multi-layered transversely isotropic media. This primarily involves examining the velocity fields of layered media using anisotropic elastic wave propagation theory, and developing inversion programs to recover elastic parameters from those velocity fields. The resolved elastic parameter information is used in carrying out further studies on the effects of seismic anisotropy on normal moveout (NMO). Mathematical analyses, numerical simulations, and physical modelling experiments are used in this research for verification purposes before application to field survey data. Numerical studies show the transmission velocity field through layered media appears to be equivalent to that through a single-layered medium, within the practical offset limits in field surveys. The elastic parameters, which describe the property of such equivalent single-layered media, can be used as apparent elastic parameters to describe the collective mechanical property of the layered media. During this research, Snell's law was used in ray tracing to determine ray paths through the interface between any two component layers. By analyzing the signals recorded by any receiver in a walkaway VSP survey, the apparent transmission velocity field for the layered media above this receiver depth was inverted. / Software was developed to recover the apparent elastic parameters for the layered media above this receiver depth using the transmission velocity field as input. Based on a two-layered model, another method was developed to recover the interval elastic parameters for an individual layer of interest, using the signals recorded by receivers on the upper and lower surfaces of this layer. The recovered elastic parameters may be considerably different from the real values if a transversely isotropic medium with a tilted symmetry axis (TTI) is treated as a transversely isotropic medium with a vertical symmetry axis (VTI). A large angle of tilt of the symmetry axis significantly influences the recorded velocity field through the medium. An inversion program was written to recover the value of the tilt angle of a TTI medium, and the elastic parameters of the medium. Programs were also developed to combine information from P, SV, and SH-waves in an inversion procedure. This capability in inversion programs enables us to use the additional information provided by a multi-component VSP survey to obtain accurate estimates of the elastic parameters of geological formations. Software testing and development was carried out on numerically generated input data. Up to 10 milliseconds of random noise in travel time was added to the input to confirm the stability of the inversion software. Further testing was carried out on physical model data where the parameters of the model were known from direct measurements. Finally the inversion software was applied to actual field data and found to give plausible results. / In software testing in the physical modelling laboratory, other practical problems were encountered. System errors caused by the disproportionately large size of the transducers used affected the accuracy of the inversion results obtained. Transducer performance was studied, and it was found that reducing the size of transducers or making offset corrections would decrease the errors caused by the disproportionately large transducer dimensions. In using the elastic parameters recovered, it was found that the elastic parameter δ significantly influences the seismic records from a horizontal reflector. The normal moveout velocity was found to show variations from the zero-offset normal moveout velocity depending on the value and sign of elastic parameter δ. New approximate expressions for anisotropic normal moveout, phase and ray velocity functions at short offsets were developed. The value of anisotropic parameter δ was found to be the major factor controlling these relations. If the recovered parameter δ has a large negative value, analytical and numerical studies demonstrated that the new expression for moveout velocity developed herein should be used instead of Thomsen's normal moveout equation.

Logistic and economic constraints often dictate the spatial sampling of a seismic survey. The process of acquisition records a finite number of spatial samples of the continuous wave field. The latter leads to a regular or irregular distribution of seismograms. Seismic reconstruction methods are used to recover non-acquired data and to synthesize a dense distribution of sources and receivers that mimics a properly sampled survey. This dissertation examines the seismic sampling problem and proposes algorithms for efficient multidimensional seismic data reconstruction. In particular, I address the problem of reconstructing irregularly sampled data using multidimensional linear prediction filters. The methodology entails a strategy that consists of two steps. First, the unaliased part of the wave field is reconstructed via Fourier reconstruction (Minimum Weighted Norm Interpolation). Then, prediction filters for all the frequencies are extracted from the reconstructed low frequencies. The latter permits the the recovery of aliased data with Multi-Step Auto-Regressive (MSAR) algorithm. The recovered prediction filters are used to reconstruct the complete data in either the f-x domain (MSAR-X) or the f-k domain (MSAR-K). The thesis also presents the use of Exponentially Weighted Recursive Least Squares (EWRLS) to estimate adaptive prediction filters for f-x seismic interpolation. Adaptive prediction filters are able to model signals where the dominant wavenumbers are varying in space. This concept leads to a f-x interpolation method that does not require windowing strategies for optimal results. In other words, adaptive prediction filters can be used to interpolate waveforms with spatially variant dips. / Geophysics

Inversion for refraction statics is a key part of three-dimensional (3D) reflection seismic processing. The present thesis has two primary goals directed toward improvement of refraction statics inversion. First, I attempt to improve the quality of the travel-time data right at the beginning of the processing sequence and before any inversion. Any error in the travel times or geometry caused during acquisition or processing would propagate into the resulting model and may harm the resulting image. To implement rigorous, model-independent data quality control, I view the first-arrival travel times as surfaces in 3D, which allows utilization of the travel-time reciprocity condition to check for errors in geometry and in first-arrival picking.<p> The second goal of this study is in development of a new inversion approach for refraction statics specifically for 3D seismic datasets. The first-break travel-times are decomposed by using a ô-p parameterization, which allows an automatic derivation of a high-quality initial subsurface model. This model is further improved by using accurate, multi-layer ray-tracing and inversion techniques to obtain accurate refraction statics. An iterative inversion scheme based on the Simultaneous Iterative Reconstruction Technique is utilized, and its performance is measured and discussed. To assess the quality of the inverse and establish the optimal grid sizes, I use several types of resolution tests. Finally, the surface consistent statics is calculated and applied to a real dataset from southern Saskatchewan. A comparison of the resulting statics model with statics calculated by using standard industry software is made, and the statics correction is incorporated in seismic processing.<p> An overall result of this study is in demonstration that the fully 3D, ô-p based travel-time inversion method works, is applicable to large seismic datasets, and results in detailed shallow subsurface models and reliable statics solutions. Several recommendations for extending and improving the proposed approaches are also made.

The recent development of satellite observations of limb scattered sunlight at optical wavelengths has afforded a new opportunity to measure the vertical structure of atmospheric composition from the upper troposphere to the mesosphere, on a global scale. The determination of profiles of atmospheric composition from observed limb radiance profiles requires two elements, a forward radiative transfer model and a species specific inversion algorithm. In this work, the development of a new, fully spherical, successive orders radiative transfer model, SASKTRAN, for the analysis of limb scattered sunlight is presented. The model is incorporated into a novel relaxation algorithm that employs spectral ratios to retrieve profiles of stratospheric aerosols from limb radiance measurements collected by the Canadian OSIRIS instrument on the Odin satellite.<p>The SASKTRAN forward model results compare favorably with both OSIRIS observations as well as with other radiative transfer model calculations while remaining computationally practical for the operational inversion of large satellite data sets.<p>The spectral ratio relaxation algorithm is able to retrieve aerosol number density profiles at stratospheric altitudes from limb radiance profiles assuming the height profile of the aerosol particle size distribution is known. The equivalent aerosol extinction derived from the OSIRIS measurements at visible wavelengths agrees with coincident occultation measurements from other satellite instrumentation to within 15% when a size distribution appropriate for background aerosol conditions is used. Finally, it is demonstrated that the incorporation of simultaneous infra-red observations at 1530 nm into the inversion yields a useful proxy for the aerosol size distribution parameters.

The Lena West property near Lac des Bois, NT, held by Diamondex Resources Ltd., is an area of interest for exploration for kimberlitic features. In 2005, Frontier Geosciences Inc. was contracted to carry out seismic reflection and time-domain transient electromagnetic (TEM) surveys to investigate the possibility of kimberlite pipes being the cause of total magnetic intensity (TMI) anomalies previously identified on the property. One small part of the property, Area 1915, was surveyed with two perpendicular seismic reflection lines 1550 m and 1790 m long and three TEM lines consisting of six or seven individual soundings each with a 200 m transmitter loop. The results generated by Frontier Geosciences did not indicate any obvious vertical features that correlated with the TMI anomaly. The purpose of this study is to reprocess the seismic reflection data using different approaches than those of Frontier Geosciences and to invert the TEM data using a 1-D inversion code, EM1DTM recently developed by the UBC Geophysical Inversion Facility, to improve upon previous results and enhance the interpretation. A secondary objective is to test the robustness of EM1DTM when applied to observed TEM data, since prior to this study it had only been applied to synthetic data. Selective bandpass filtering, refraction and residual statics and f-x deconvolution procedures contributed to improved seismic images to the recorded two-way traveltime of 511.5 ms (approximately 1100 m depth). The TEM data were successfully inverted and converted to pseudo 2-D recovered resistivity sections that showed similar results to those from Frontier Geosciences. On the final seismic reflection sections, several strong reflectors are identified and the base of the overlying sedimentary layers is interpreted at a depth of ~600 m. The TEM results show consistent vertical structure with minimum horizontal variation across all lines to a valid depth of ~150 m. However, neither TEM nor seismic reflection results provide any information that correlates well with the observed TMI anomaly.

The recent development of satellite observations of limb scattered sunlight at optical wavelengths has afforded a new opportunity to measure the vertical structure of atmospheric composition from the upper troposphere to the mesosphere, on a global scale. The determination of profiles of atmospheric composition from observed limb radiance profiles requires two elements, a forward radiative transfer model and a species specific inversion algorithm. In this work, the development of a new, fully spherical, successive orders radiative transfer model, SASKTRAN, for the analysis of limb scattered sunlight is presented. The model is incorporated into a novel relaxation algorithm that employs spectral ratios to retrieve profiles of stratospheric aerosols from limb radiance measurements collected by the Canadian OSIRIS instrument on the Odin satellite.<p>The SASKTRAN forward model results compare favorably with both OSIRIS observations as well as with other radiative transfer model calculations while remaining computationally practical for the operational inversion of large satellite data sets.<p>The spectral ratio relaxation algorithm is able to retrieve aerosol number density profiles at stratospheric altitudes from limb radiance profiles assuming the height profile of the aerosol particle size distribution is known. The equivalent aerosol extinction derived from the OSIRIS measurements at visible wavelengths agrees with coincident occultation measurements from other satellite instrumentation to within 15% when a size distribution appropriate for background aerosol conditions is used. Finally, it is demonstrated that the incorporation of simultaneous infra-red observations at 1530 nm into the inversion yields a useful proxy for the aerosol size distribution parameters.