Parametric equations are used to represent the pathway of an object in terms of time or another changing variable. This allows, for example, for equations that are written using two variables to be examined in terms of the passage of time. In this paper the author examines two traditional application problems whose solutions can be enriched through the use of parametric equations. In the first, the falling ladder problem, a ladder is leaned against a wall then pulled away with a constant velocity. Deriving parametric equations for this scenario permits the pathway of the ladder to be plotted. Parametric equations also make it possible for the horizontal and vertical velocities of the ladder to be examined separately. The second problem is that of maximizing the length of a ladder that can fit around a hallway corner. In this problem an envelope algorithm is first developed, then parametrized to further investigate this scenario. Using these two situations, this report ultimately shows how parametric equations can be used to give a more thorough approach to some of today’s most classic calculus problems. / text

This thesis explores three topics in the field of cost estimation for Unmanned Autonomous Systems. First, we propose a common definition of an Unmanned Autonomous System. We accomplish this through exhausting the literature in the areas cost estimation, autonomy in its current form, and how such advanced systems might be integrated into their environment. Second, we introduce a method to estimate the cost of Unmanned Autonomous Systems utilizing existing parametric cost estimation tools: SEER–HDR, COCOMO II, COSYSMO, and two cost estimating relationships–weight and performance. This discussion is guided by focusing on how current tools attempt to account for emergent systems. We also attempt to address challenges surrounding autonomy. To address these challenges from a cost perspective, this thesis recommends modifications to parameters within COCOMO II–via the use of object-oriented function points in lieu of current methods, and COSYSMO–via the introduction of two cost drivers namely, TVED and HRI-T. Third, we conduct analysis on four current Army Unmanned Autonomous Systems in an attempt to establish early trends within existing estimates. Finally, we explore areas of further research and discuss the implications of how pursing a more adequate cost model will lead to a better understanding of this ill-defined paradigm. *This material is based upon work supported by the Naval Postgraduate School Acquisition Research Program under Grant No. N00244-15-1-0008. The views expressed in written materials or publications, and/or made by speakers, moderators, and presenters, do not necessarily reflect the official policies of the Naval Postgraduate School nor does mention of trade names, commercial practices, or organizations imply endorsement by the U.S. Government.

Σκοπός της διπλωματική αυτής εργασίας είναι η παραμετρική διερεύνηση ενός αυτόνομου φωτοβολταϊκού συστήματος. Η διερεύνηση αυτή γίνεται για έξι πόλης της Βορείου Ελλάδος με στόχο την εξαγωγή γενικών συμπερασμάτων σχετικά με τον σχεδιασμό αυτόνομων φωτοβολταϊκών συστημάτων. Πριν προχωρήσουμε στην παραμετρική διερεύνηση, θεωρήθηκε σκόπιμο να μελετήσουμε θεωρητικά τα κυριότερα μέρη ενός φωτοβολταϊκού συστήματος. Αρχικά, παρατίθεται μια σύντομη Εισαγωγή στην οποία παρουσιάζεται το ενεργειακό, ενώ τονίζεται η σημασία της ανάπτυξης και βελτίωσης ηλεκτροπαραγωγικών μεθόδων βασιζόμενες στις Ανανεώσιμες Πηγές Ενέργειας (Α.Π.Ε.). Στο κεφάλαιο 1, αναλύεται η αρχή λειτουργίας των ηλιακών κυττάρων. Επιπλέον, γίνεται αναφορά στην εξίσωση, την I-V χαρακτηριστική και την απόδοση των Φ/Β κυττάρων, ενώ αναφέρονται και τα κυριότερα είδη αυτών. Στο κεφάλαιο 2, αναφερόμαστε στα κύρια δομικά χαρακτηριστικά μιας Φ/Β συστοιχίας, καθώς και στα προβλήματα που αυτή αντιμετωπίζει και την επίλυση αυτών. Στο κεφάλαιο 3 παρατίθεται η αρχή λειτουργίας καθώς και η δομή των δευτερευόντων συσσωρευτών. Επίσης, ειδική αναφορά γίνεται στους συσσωρευτές Νικελίου-Καδμίου. Στο κεφάλαιο 4, αναπτύσσεται το μοντέλο το οποίο χρησιμοποιούμε για να μετατρέψουμε τιμές της προσπίπτουσας ηλιακής ακτινοβολίας σε οριζόντια επιφάνεια σε αντίστοιχες τιμές σε κεκλιμένη επιφάνεια. Στο κεφάλαιο 5, χρησιμοποιούμε το μοντέλο που αναπτύχθηκε στο κεφάλαιο 4 για τον υπολογισμό τιμών της ηλιακής ακτινοβολίας σε κεκλιμένη επιφάνεια, για τις έξι υπό μελέτη πόλεις, χρησιμοποιώντας ως τιμές εισόδου τις τιμές που παρατίθενται στον πίνακα Α.1 (Παράρτημα). Οι τιμές που υπολογίζουμε στο κεφάλαιο αυτό μπορούν να χρησιμοποιηθούν στο σχεδιασμό Φ/Β συστημάτων συνδεδεμένων με το δίκτυο. Στο κεφάλαιο 6, αναπτύσσεται μια μεθοδολογία υπολογισμού αυτόνομων Φ/Β συστημάτων. Στα κεφάλαια 7 και 8, χρησιμοποιούμε την μεθοδολογία που αναπτύχθηκε στο προηγούμενο κεφάλαιο για να προσομοιώσουμε την λειτουργία ενός αυτόνομου Φ/Β συστήματος για ετήσια και καλοκαιρινή λειτουργία αντίστοιχα. Μάλιστα, στο κεφάλαιο 8 χρησιμοποιούμε και μια παραλλαγή της βασικής μεθόδου για τη μελέτη της καλοκαιρινής περιόδου λειτουργίας του Φ/Β συστήματος. Τέλος, στον επίλογο γίνεται μια συνολική αποτίμηση όσων έγιναν στην διπλωματική αυτή εργασία και παρατίθενται κάποια γενικά συμπεράσματα. / This thesis deals with the parametric study of a Stand Alone Photovoltaic System. This study is being conducted in six cities of Northern Greece, for the purpose of extracting general guidelines regarding the design of stand-alone PV systems. Before we proceed with the study, it is considered useful to study theoretically the main parts of a stand-alone PV system. We start off with a short introduction in which the global energy problem is being described. Emphasis is also given to the importance of developing energy production methods based on Renewable Energy Sources. Chapter 1 deals with the working principle of solar cells. Furthermore, we also investigate the equivalent circuit model, the I-V curve and the efficiency of solar cells. Finally, the primary types of solar cells are being demonstrated. In chapter 2 we study the main parts of a PV array. We also refer to the problems that a PV array faces during its operation, as well as the possible solutions of these problems. In chapter 3 we refer to the working principles and to the structure of batteries. In particular, we study Nickel-Cadmium batteries. In chapter 4, the model that is used in order to convert solar radiation values, taken in horizontal surface, to corresponding values taken in inclined surface, is being described. In chapter 5, we use the model described in chapter 4 in order to calculate values of solar radiation in inclined surface, for the six cities in which this study takes place. The data based on which we calculate the above values are being demonstrated in table A.1 (appendix A). The values calculated in this chapter can be used in the design of a grid connected PV system. In chapter 6, a methodology used in designing a stand-alone PV system is being described. In chapters 7 and 8, we use the above methodology in order to simulate the operation of a stand-alone PV system during annual and summer working periods correspondingly. In chapter 8 we also use a slight alteration of the above methodology in order to study the operation of a stand-alone PV system, during a summer working period even further. Finally, an overall valuation of this thesis is made in the epilogue. Furthermore, some overall conclusions are being presented.

Terahertz (THz) heterodyne receiver systems are required by NASA to monitor gas concentrations related to the Earth's ozone depletion. To this end, NASA needs compact, solid state, tunable THz local oscillators. THz LOs have been developed using three means: 1) All-electronic LOs using mixers in combination with Gunn oscillators, 2) Hybrid Photo-electronic LOs using a cw analog of the Auston switch, and 3) All-photonic THz LOs using coherent sources, such as vapor lasers or solid-state Quantum Cascade Lasers, and down converting lasers using nonlinear crystals. In this dissertation, we began with two frequency stabilized Nd:YAG lasers, locked to a common reference cavity, as a starting point to having a stable input into a nonlinear optical frequency conversion system. Following this, we explored the nonlinear crystals useful for THz generation, and the phasematching schemes that could be employed by each. We concluded by settling on highly insulating III-V semiconductor crystals as the proper choice of nonlinear element, and put together a new phasematching method that is most useful for them.

Volvo Aero Corporation takes part in a development project called Future Launchers Preparatory Program (FLPP) which aims to develop Next Generation Launchers (NGL) for future space flights. FLPP involves several projects and one these are focused on the development of the next generation rocket engines for the NGL. The environment of a rocket engine is extremely hostile, characterized by high pressure levels and rapid thermal transients. Even though the components are manufactured from super alloys, the life of these components is measured in seconds. In the light of these facts, it is obvious that all components have to be optimized to the last detail. This thesis work is a part of the optimization procedure with the objective to perform a parametric study of manifolds that will be particular useful during the concept work of the turbines for the FLPP program. The methods of probabilistic analysis have been employed in this study. This approach involves Ishikawa analysis (Cause and Effects) as well deriving transfer functions through defining and performing simulations in a structured manner according to a Design of Experiment model. Transfer functions, which are derived through a series of Finite Element Analysis, describe the relation between design parameter and stress levels. The transfer function can be considered as a simplified physical model which only is applicable within the range used of the design parameters. The use of transfer function is especially powerful when performing Monte Carlo simulations to determine the likelihood of plasticity. One short coming of transfer functions is that only the parameters included from the beginning can be altered and assessed. One also have to consider the simplifications introduced through the modelling, such as transfer functions derived using linear elastic simulations can not be used for assessment of plastic deformations. The method developed in this thesis will be further developed in following studies. This report is therefore meant to serve as a guide for the next investigator at Volvo Aero Corporation.

This paper offers to measure efficiency of banks in Sub Saharan Africa and its determining input andout put factors on two fonts. At this purpose, we applied the first font; Data Envelopment Analysis(DEA) for assessing efficiency level. The actual and target level of inputs/outputs to foster efficiencyare shown in the results. Secondly, the banks ratio analysis measuring banks performance throughreturns volatility for each bank, asset utilization and provision for bad and doubtful debts over thestudy period are all used as tools for this analysis. Our results suggest that Sub Saharan AfricanBanks are about 98.35% efficient. We are aware that the level of efficiency could be subject to up anddown swing if environmental factors influencing banks efficiency where taken into consideration.Finally, our result (DEA) is more sensitive to loans, other liabilities, other non interest expense,securities and deposit.

This research work studies the problem of identifying and predicting the trends of a single financial target variable in a multivariate setting. The machine learning point of view on this problem is presented in chapter I. The efficient market hypothesis, which stands in contradiction with the objective of trend prediction, is first recalled. The different schools of thought in market analysis, which disagree to some extent with the efficient market hypothesis, are reviewed as well. The tenets of the fundamental analysis, the technical analysis and the quantitative analysis are made explicit. We particularly focus on the use of machine learning techniques for computing predictions on time-series. The challenges of dealing with dependent and/or non-stationary features while avoiding the usual traps of overfitting and data snooping are emphasized. Extensions of the classical statistical learning framework, particularly transfer learning, are presented. The main contribution of this chapter is the introduction of a research methodology for developing trend predictive numerical models. It is based on an experimentation protocol, which is made of four interdependent modules. The first module, entitled Data Observation and Modeling Choices, is a preliminary module devoted to the statement of very general modeling choices, hypotheses and objectives. The second module, Database Construction, turns the target and explanatory variables into features and labels in order to train trend predictive numerical models. The purpose of the third module, entitled Model Construction, is the construction of trend predictive numerical models. The fourth and last module, entitled Backtesting and Numerical Results, evaluates the accuracy of the trend predictive numerical models over a "significant" test set via two generic backtesting plans. The first plan computes recognition rates of upward and downward trends. The second plan designs trading rules using predictions made over the test set. Each trading rule yields a profit and loss account (P&L), which is the cumulated earned money over time. These backtesting plans are additionally completed by interpretation functionalities, which help to analyze the decision mechanism of the numerical models. These functionalities can be measures of feature prediction ability and measures of model and prediction reliability. They decisively contribute to formulating better data hypotheses and enhancing the time-series representation, database and model construction procedures. This is made explicit in chapter IV. Numerical models, aiming at predicting the trends of the target variables introduced in chapter II, are indeed computed for the model construction methods described in chapter III and thoroughly backtested. The switch from one model construction approach to another is particularly motivated. The dramatic influence of the choice of parameters - at each step of the experimentation protocol - on the formulation of conclusion statements is also highlighted. The RNN procedure, which does not require any parameter tuning, has thus been used to reliably study the efficient market hypothesis. New research directions for designing trend predictive models are finally discussed.

This thesis presents a Hamiltonian formulation of the electromagnetic fields in structured (inhomogeneous) media of arbitrary dimensionality, with arbitrary material dispersion and absorption consistent with causality. The method is based on an identification of the photonic component of the polariton modes of the system. Although the medium degrees of freedom are introduced in an oscillator model, only the macroscopic response of the medium appears in the derived eigenvalue equation for the polaritons. For both the discrete transparent-regime spectrum and the continuous absorptive-regime spectrum, standard codes for photonic modes in nonabsorptive systems can easily be leveraged to calculate polariton modes. Two applications of the theory are presented: pulse propagation and spontaneous parametric down-conversion (SPDC). In the propagation study, the dynamics of the nonfluctuating part of a classical-like pulse are expressed in terms of a Schr\"{o}dinger equation for a polariton effective field. The complex propagation parameters of that equation can be obtained from the same generalized dispersion surfaces typically used while neglecting absorption, without incurring additional computational complexity. As an example I characterize optical pulse propagation in an Au/MgF$_2$ metallodielectric stack, using the empirical response function, and elucidate the various roles of Bragg scattering, interband absorption and field expulsion. Further, I derive the Beer coefficient in causal structured media. The SPDC calculation is rigorous, captures the full 3D physics, and properly incorporates linear dispersion. I obtain an expression for the down-converted state, quantify pair-production properties, and characterize the scaling behavior of the SPDC energy. Dispersion affects the normalization of the polariton modes, and calculations of the down-conversion efficiency that neglect this can be off by 100$\%$ or more for common media regardless of geometry if the pump is near the band edge. Furthermore, I derive a 3D three-wave group velocity walkoff factor; due to the interplay of a topological property with a symmetry property, I show that even if down-conversion is into a narrow forward cone, neglect of the transverse walkoff can lead to an overestimate of the SPDC energy by orders of magnitude.

This thesis presents a Hamiltonian formulation of the electromagnetic fields in structured (inhomogeneous) media of arbitrary dimensionality, with arbitrary material dispersion and absorption consistent with causality. The method is based on an identification of the photonic component of the polariton modes of the system. Although the medium degrees of freedom are introduced in an oscillator model, only the macroscopic response of the medium appears in the derived eigenvalue equation for the polaritons. For both the discrete transparent-regime spectrum and the continuous absorptive-regime spectrum, standard codes for photonic modes in nonabsorptive systems can easily be leveraged to calculate polariton modes. Two applications of the theory are presented: pulse propagation and spontaneous parametric down-conversion (SPDC). In the propagation study, the dynamics of the nonfluctuating part of a classical-like pulse are expressed in terms of a Schr\"{o}dinger equation for a polariton effective field. The complex propagation parameters of that equation can be obtained from the same generalized dispersion surfaces typically used while neglecting absorption, without incurring additional computational complexity. As an example I characterize optical pulse propagation in an Au/MgF$_2$ metallodielectric stack, using the empirical response function, and elucidate the various roles of Bragg scattering, interband absorption and field expulsion. Further, I derive the Beer coefficient in causal structured media. The SPDC calculation is rigorous, captures the full 3D physics, and properly incorporates linear dispersion. I obtain an expression for the down-converted state, quantify pair-production properties, and characterize the scaling behavior of the SPDC energy. Dispersion affects the normalization of the polariton modes, and calculations of the down-conversion efficiency that neglect this can be off by 100$\%$ or more for common media regardless of geometry if the pump is near the band edge. Furthermore, I derive a 3D three-wave group velocity walkoff factor; due to the interplay of a topological property with a symmetry property, I show that even if down-conversion is into a narrow forward cone, neglect of the transverse walkoff can lead to an overestimate of the SPDC energy by orders of magnitude.

The paper is devoted to statistical nonparametric estimation of multivariate distribution density. The influence of data pre-clustering on the estimation accuracy of multimodal density is analysed by means of the Monte-Carlo method.