The number of horizontal wells is increasing rapidly in all over the world with the growth of new technological developments. During horizontal well drilling, much more complex problems occur when compared with vertical well drilling, such as decrease in load transfer to the bit, tubular failure, tubular fatigue and tubular lock-up. This makes selection of appropriate tubular and making the right drill string design more important. As the total compression load on the horizontal section increases, the behavior of the tubular changes from straight to sinusoidal buckling, and if the total compression load continues to increase the behavior of the tubular changes to helical buckling. Determination of critical buckling loads with finite element method (FEM) in horizontal wells is the main objective of this study. Initially, a computer program (ANSYS) that uses FEM is employed to simulate different tubular and well conditions. Four different pipe sizes, four different wellbore sizes and three different torque values are used to model the cases. Critical buckling load values corresponding to significant variables are collected from these simulated cases. The results are classified into different buckling modes according to the applied weight on bit values and the main properties of the simulated model, such as modulus of elasticity, moment of inertia of tubular cross section, weight per unit length of tubular and radial clearance between the wellbore and the tubular. Then, the boundary equations between the buckling modes are obtained. The equations developed in this thesis by simulating the cases for the specific tubular sizes are used to make a comparison between the critical buckling load values from the models in the literature and this work. It is observed that the results of this work fit with literature models as the tubular size increases. The influence of torque on critical buckling load values is investigated. It is observed that torque has a slight effect on critical buckling load values. Also the applicability of ANSYS for buckling problems was revealed by comparing the ANSYS results with the literature models&amp / #8217 / results and the experimental study in the literature.

In this thesis we study low correlation zone (LCZ) sequence sets and a class of quadratic forms. In the first part we obtain two new classes of optimal LCZ sequence sets. In our first construction using a suitable orthogonal transformation we extend some results of [21]. We give new classes of LCZ sequence sets defined over Z4 in our second construction. We show that our LCZ sequence sets are optimal with respect to the Tang, Fan and Matsufiji bound [37]. In the second part we consider some special linearized polynomials and corresponding quadratic forms. We compute the number of solutions of certain equations related to these quadratic forms and we apply these result to obtain curves with many rational points.

In statistics, regression analysis is a technique, used to understand and model the relationship between a dependent variable and one or more independent variables. Multiple Adaptive Regression Spline (MARS) is a form of regression analysis. It is a non-parametric regression technique and can be seen as an extension of linear models that automatically models non-linearities and interactions. MARS is very important in both classification and regression, with an increasing number of applications in many areas of science, economy and technology. In our study, we analyzed Generalized Partial Linear Models (GPLMs), which are particular semiparametric models. GPLMs separate input variables into two parts and additively integrates classical linear models with nonlinear model part. In order to smooth this nonparametric part, we use Conic Multiple Adaptive Regression Spline (CMARS), which is a modified form of MARS. MARS is very benefical for high dimensional problems and does not require any particular class of relationship between the regressor variables and outcome variable of interest. This technique offers a great advantage for fitting nonlinear multivariate functions. Also, the contribution of the basis functions can be estimated by MARS, so that both the additive and interaction effects of the regressors are allowed to determine the dependent variable. There are two steps in the MARS algorithm: the forward and backward stepwise algorithms. In the first step, the model is constructed by adding basis functions until a maximum level of complexity is reached. Conversely, in the second step, the backward stepwise algorithm reduces the complexity by throwing the least significant basis functions from the model. In this thesis, we suggest not using backward stepwise algorithm, instead, we employ a Penalized Residual Sum of Squares (PRSS). We construct PRSS for MARS as a Tikhonov Regularization Problem. We treat this problem using continuous optimization techniques which we consider to become an important complementary technology and alternative to the concept of the backward stepwise algorithm. Especially, we apply the elegant framework of Conic Quadratic Programming (CQP) an area of convex optimization that is very well-structured, hereby, resembling linear programming and, therefore, permitting the use of interior point methods. At the end of this study, we compare CQP with Tikhonov Regularization problem for two different data sets, which are with and without interaction effects. Moreover, by using two another data sets, we make a comparison between CMARS and two other classification methods which are Infinite Kernel Learning (IKL) and Tikhonov Regularization whose results are obtained from the thesis, which is on progress.

The premise of this research is the concept, development, and application of an approximate relation for the material balance of abnormally-pressured gas reservoirs. The approximation is formulated directly from the rigorous material balance for the case of an abnormally-pressured gas reservoir. The primary assumption in this derivation is that WGp <1 or Ce(p)(pi-p)<1. Further, we can proceed by assuming that W is either constant or some arbitrary function. If we assume W=constant, then the following form results: At first glance there may be concern that this approximation is not sufficiently valid for field applications — however, we have shown this relation to be an extraordinarily accurate approximation of the rigorous material balance. This result is suited not only for use as a characteristic model, but also for use as a data analysis mechanism (i.e., this result is used to develop a suite of analysis plots, plotting functions, a type curve, etc.). In this work we provide the following new results: 1) A suite of 6 (six) plotting functions based on the p/z-Gp2 material balance model. 2) A suite of 4 (four) p/z-Gp performance plots which are used to calibrate analysis. 3) A new type curve in terms of a dimensionless pressure function (pD=(pi/zi-p/z)/pi/zi) versus a dimensionless cumulative production function (GpD=Gp/G), where the type curve solution is based on the new p/z-Gp^2 (a quadratic material balance) model.

This study presents the results of an extraction of the 2nd-order nonlinear responses from model test data. Emphasis is given on the effects of assumptions made for the Gaussian and non-Gaussian input on the estimation of the 2nd-order response, employing the quadratic Volterra model. The effects of sea severity and data length on the estimation of response are also investigated at the same time. The data sets used in this study are surge forces on a fixed barge, a surge motion of a compliant mini TLP (Tension Leg Platform), and surge forces on a fixed and truncated column. Sea states are used from rough sea (Hs=3m) to high sea (Hs=9m) for a barge case, very rough sea (Hs=3.9m) for a mini TLP, and phenomenal sea (Hs=15m) for a truncated column. After the estimation of the response functions, the outputs are reconstructed and the 2nd order nonlinear responses are extracted with all the QTF distributed in the entire bifrequency domain. The reconstituted time series are compared with the experiment in both the time and frequency domains. For the effects of data length on the estimation of the response functions, 3, 15, and 40- hour data were investigated for a barge, but 3-hour data was used for a mini TLP and a fixed and truncated column due to lack of long data. The effects of sea severity on the estimation of the response functions are found in both methods. The non-Gaussian method for estimation is more affected by data length than the Gaussian method.

This study utilized historical population statistics data and related reports to investigate the population distribution and transition trend of Kaohsiung Main Urban Area. There were four purposes of this study; firstly to understand the current population distribution pattern of Kaohsiung Main Urban Area, secondly to investigate the change trend of Kaohsiung Main Urban Area in the past 36 years, thirdly using Kaohsiung Main Urban Area population data to verify the population density model and to examine the correspondence with the current society, and fourthly to explore the impact of the establishment of Kaohsiung Mass Rapid Transit System and Taiwan High Speed Rail to the transition and distribution of population in Kaohsiung Main Urban Area. This study employed the population statistical database from year 1972 to 2007, and divided the Kaohsiung metropolitan area into 32 sub-divisions. The population data was re-organized accordingly in order to perform the systematic analyses and exploration in making the understanding of the current population status and transition process. Furthermore, employing the population data of Kaohsiung metropolitan area, the validation of negative exponential model and quadratic exponential model, the population model proposed by Clark and Newling respectively 58 year ago, were performed to verify the applicability of the theories to modern society. In addition, this study also performed the exploration of population transition and distribution in Kaohsiung metropolitan area during the construction period of Kaohsiung Mass Rapid Transit System and Taiwan High Speed Rail and could be of reference to urban planning and development in the future. This study found that both Clark and Newling¡¦s population model still has high interpretation capability after 58 years later. The Kaohsiung metropolitan area population distribution model and trend forecast proposed by Ho in 1991 is still true. However, because of the slow down in overall development trend of Taiwan, the transition trend of Kaohsiung metropolitan also mitigated. Besides, due to the trend mitigation, the volcano peak phenomenon which was mentioned in the literature review will be postponed and expected to happen in year 2018.

<p>Arbetet har utförts på Saab Bofors Dynamics i Karlskoga och dess syfte var att undersöka om det är möjligt att använda modellbaserad prediktionsreglering, MPC, vid slutfasstyrning av en viss typ av robot. Som referensram används linjärkvadratisk reglering, LQ, eftersom denna reglermetod har undersökts tidigare och visat sig fungera bra vid slutfasstyrning, dock för en annan typ av robot. Anledningen till att man vill undersöka om det är möjligt att använda MPC är att styrlagen enkelt tar hand om begränsningar på systemet på ett direkt och intuitivt sätt.</p><p>Styrlagarnas uppgift är att styra en robot i dess slutfas då det finns krav och önskemål på roboten som bör vara uppfyllda. Till exempel finns det begränsningar på styrsignalen samt önskemål om att träff ska ske i en viss träffpunkt och även med en viss träffvinkel. För att utvärdera resultaten undersöks och jämförs de två styrlagarnas prestanda och robusthet.</p><p>För att kunna utvärdera styrlagarnas egenskaper och jämföra dem implementeras de båda i en befintlig detaljerad simuleringsmiljö, som har utvecklats på Saab Bofors Dynamics i Karlskoga.</p><p>De prestanda och robusthetstester som har utförts uppvisar små skillnader på de två styrlagarna och slutsatsen blir därmed att det är möjligt att använda modellbaserad prediktionsreglering vid slutfasstyrning av en viss typ av robot eftersom det sedan tidigare är känt att linjärkvadratisk reglering är en bra styrlag att använda. För att se vilken av de två styrlagarna som är bäst vid slutfasstyrning av en viss typ av robot behöver det göras vissa ändringar och mer detaljerade undersökningar utföras.</p>

Thesis (M.S.)--Mississippi State University. Department of Aerospace Engineering. / Title from title screen. Includes bibliographical references.

In 1955, Cassels proved a now celebrated theorem giving a search bound algorithm for determining whether a quadratic form has a nontrivial zero over the rationals. Since then, his work has been greatly generalized, but most of these newer techniques do not follow his original method of proof. In this thesis, we revisit his 1955 proof, modernize his tools and language, and use this machinery to prove more general theorems regarding height bounds for the common zeros of a system of polynomials in terms of the heights of those polynomials. We then use these theorems to give a short proof of a more general (albeit, known) version of Cassels' Theorem and give some weaker results concerning the rational points of a cubic or a pair of quadratics. / text

A quadratic form on \(\mathbb{R}^n\) is a map of the form \(x \mapsto x^T M x\), where M is a symmetric \(n \times n\) matrix. A quadratic map from \(\mathbb{R}^n\) to \(\mathbb{R}^m\) is a map, all m of whose components are quadratic forms. One of the two central questions in this thesis is this: when is the image of a quadratic map \(Q: \mathbb{R}^n \rightarrow \mathbb{R}^m\) a convex subset of \(\mathbb{R}^m\)? This question has intrinsic interest; despite being only a degree removed from linear maps, quadratic maps are not well understood. However, the convexity properties of quadratic maps have practical consequences as well: underlying every semidefinite program is a quadratic map, and the convexity of the image of that map determines the nature of the solutions to the semidefinite program. Quadratic maps that map into \(\mathbb{R}^2\) and \(\mathbb{R}^3\) have been studied before (in (Dines, 1940) and (Calabi, 1964) respectively). The Roundness Theorem, the first of the two principal results in this thesis, is a sufficient and (almost) necessary condition for a quadratic map \(Q: \mathbb{R}^n \rightarrow \mathbb{R}^m\) to have a convex image when \(m \geq 4\), \(n \geq m\) and \(n \not= m + 1\). Concomitant with the Roundness Theorem is an important lemma: when \(n < m\), quadratic maps from \(\mathbb{R}^n\) to \(\mathbb{R}^m\)seldom have convex images. This second result in this thesis is a controllability condition for bilinear systems defined on direct products of the form \(\mathcal{G} \times\mathcal{G}\), where \(\mathcal{G}\) is a simple Lie group. The condition is this: a bilinear system defined on \(\mathcal{G} \times\mathcal{G}\) is not controllable if and only if the Lie algebra generated by the system’s vector fields is the graph of some automorphism of \(\mathcal{g}\), the Lie algebra of \(\mathcal{G}\). / Engineering and Applied Sciences