Cluster Analysis of the Newcastle Electronic Corpus of Tyneside English: In A Comparison of Methods

This article examines the feasibility of an empirical approach to sociolinguistic analysis of the Newcastle Electronic Corpus of Tyneside English using exploratory multivariate methods. It addresses a known problem with one class of such methods, hierarchical cluster analysis—that different clustering algorithms can yield different analyses of the same data set, and that there is no obvious way of selecting the best one. The proposed solution is to analyze the data using hierarchical methods in conjunction with one or more fundamentally different types of clustering method, and then to select the analysis on which the hierarchical and the other method(s) agree most closely. A dimensionality reduction method, the self-organizing map (SOM), is used to exemplify this approach. The result is a close though not perfect match between the SOM and complete-link hierarchical analyses, but there is an important reservation—the SOM results vary with changes in user-defined training parameters, and are consequently also open to the criticism of inconsistency. The SOM cannot therefore be an objective arbiter for hierarchical clustering, but the analysis on which they agree gives a better basis for understanding the structure of the data than either method can provide on its own

Algebraic technique for mixed least squares and total least squares problem in the reduced biquaternion algebra

This paper presents the reduced biquaternion mixed least squares and total least squares (RBMTLS) method for solving an overdetermined system $AX \approx B$ in the reduced biquaternion algebra. The RBMTLS method is suitable when matrix $B$ and a few columns of matrix $A$ contain errors. By examining real representations of reduced biquaternion matrices, we investigate the conditions for the existence and uniqueness of the real RBMTLS solution and derive an explicit expression for the real RBMTLS solution. The proposed technique covers two special cases: the reduced biquaternion total least squares (RBTLS) method and the reduced biquaternion least squares (RBLS) method. Furthermore, the developed method is also used to find the best approximate solution to $AX \approx B$ over a complex field. Lastly, a numerical example is presented to support our findings.Comment: 19 pages, 3 figure

Mechanical models of proteins

textIn general, this dissertation is concerned with modeling of mechanical behavior of protein molecules. In particular, we focus on coarse-grained models, which bridge the gap in time and length scale between the atomistic simulation and biological processes. The dissertation presents three independent studies involving such models. The first study is concerned with a rigorous coarse-graining method for dynamics of linear systems. In this method, as usual, the conformational space of the original atomistic system is divided into master and slave degrees of freedom. Under the assumption that the characteristic timescales of the masters are slower than those of the slaves, the method results in Langevin-type equations of motion governed by an effective potential of mean force. In addition, coarse-graining introduces hydrodynamic-like coupling among the masters as well as non-trivial inertial effects. Application of our method to the long-timescale part of the relaxation spectra of proteins shows that such dynamic coupling is essential for reproducing their relaxation rates and modes. The second study is concerned with calibration of elastic network models based on the so-called B-factors, obtained from x-ray crystallographic measurements. We show that a proper calibration procedure must account for rigid-body motion and constraints imposed by the crystalline environment on the protein. These fundamental aspects of protein dynamics in crystals are often ignored in currently used elastic network models, leading to potentially erroneous network parameters. We develop an elastic network model that properly takes rigid-body motion and crystalline constraints into account. This model reveals that B-factors are dominated by rigid-body motion rather than deformation, and therefore B-factors are poorly suited for identifying elastic properties of protein molecules. Furthermore, it turns out that B-factors for a benchmark set of three hundred and thirty protein molecules can be well approximated by assuming that the protein molecules are rigid. The third study is concerned with the polymer mediated interaction between two planar surfaces. In particular, we consider the case where a thin polymer layer bridges two parallel plates. We consider two models of monodisperse and polydisperse for the polymer layer and obtain an analytical expression for the force-distance relationship of the two plates.Engineering Mechanic

Relieving the fermionic and the dynamical sign problem: Multilevel Blocking Monte Carlo simulations

This article gives an introduction to the multilevel blocking (MLB) approach to both the fermion and the dynamical sign problem in path-integral Monte Carlo simulations. MLB is able to substantially relieve the sign problem in many situations. Besides an exposition of the method, its accuracy and several potential pitfalls are discussed, providing guidelines for the proper choice of certain MLB parameters. Simulation results are shown for strongly interacting electrons in a 2D parabolic quantum dot, the real-time dynamics of several simple model systems, and the dissipative two-state dynamics (spin-boson problem).Comment: Review, 20 pages REVTeX, incl. 7 figure

AUTOMATIC FAÇADE SEGMENTATION FOR THERMAL RETROFIT

Abstract. In this paper we present an automated method to derive highly detailed 3D vector models of modern building facades from terrestrial laser scanning data. The developed procedure can be divided into two main steps: firstly the main elements constituting the facade are identified by means of a segmentation process, then the 3D vector model is generated including some priors on architectural scenes. The identification of main facade elements is based on random sampling and detection of planar elements including topology information in the process to reduce under- and over-segmentation problems. Finally, the prevalence of straight lines and orthogonal intersections in the vector model generation phase is exploited to set additional constraints to enforce automated modeling. Contemporary a further classification is performed, enriching the data with semantics by means of a classification tree. The main application field for these vector models is the design of external insulation thermal retrofit. In particular, in this paper we present a possible application for energy efficiency evaluation of buildings by mean of Infrared Thermography data overlaid to the facade model

A Framework for Low Complexity Least-Squares Localization With High Accuracy

In this paper, a new framework is proposed for least-squares localization based on estimated ranges, coveringtime-difference-of-arrival (TDoA), time-of-arrival (ToA), and received signal strength (RSS) cases. The multidimensional nonlinear localization problem is first transformed to a lower dimension and then solved iteratively. Within the proposed transformed least-squares (TLS) framework, we introduce a method in which the localization problem is transformed to one dimension (1-D). In this way, compared to the classical nonlinear least-squares (NLS) type of methods, the amount of computations in each iteration is greatly reduced; a reduction of 67% for a 3-D positioning system is shown. Hence, the introduced 1-D iterative (1DI) method is fairly light on the computational load.The way to choose the 1-D parameter is proposed, and theoretical expressions for the convergence rate and the root- mean-squared error (RMSE) of the 1DI estimator are derived. Validation is performed mainly based on actual ultra-wideband (UWB) radio measurements, collected in typical office environments, with signal bandwidths varying from 0.5 to 7.5 GHz. Supplementary simulations are also included for validation. Results show that, in terms of RMSE, the 1DI method performs better than the linear least-squares (LLS) method, where the solution is obtained noniteratively, and performs similarly as NLS, especially in TDoA cases

Remote sensing and data fusion of cultural and physical landscapes

This dissertation is written as part of the three-article option offered by the Geography Department at UNC Greensboro. Each article addresses specific research issues within Remote Sensing, Photogrammetry, and three-dimensional modeling related structural and subsurface remote sensing of historic cultural landscapes. The articles submitted in this dissertation are both separate study sites and research questions, but the unifying theme of geographic research methods applies throughout. The first article is titled Terrestrial Lidar and GPR Investigations into the Third Line of Battle at Guilford Courthouse National Military Park, Guilford County, North Carolina is published in the book Digital Methods and Remote Sensing in Archaeology: Archaeology in the Age of Sensing. Forte, Maurizio, Campana, Stefano R.L. (Eds.) 2016. The results of the research demonstrate the successful exportation of GPR data into three-dimensional point clouds. Subsequently, the converted GPR points in conjunction with the TLS were explored to aid in the identification of the colonial subsurface. The second article submitted for consideration is titled “Three-Dimensional Modeling using Terrestrial LiDAR, Unmanned Aerial Vehicles, and Digital Cameras at House in the Horseshoe State Historic Site, Sanford, North Carolina.” There are two different research components to this study, modeling a structure and the landscape. The structure modeling section compares three different remote sensing approaches to the capture and three-dimensional model creation of a historic building. A detailed comparison is made between the photogrammetric models generated from digital camera photography, a terrestrial laser scanner (TLS) and an unmanned aerial vehicle (UAS). The final article, “Geophysical Investigations at the Harper House Bentonville Battlefield, NC State Historic Site” submitted focuses on the Harper House located in at the Bentonville Civil War battlefield. UNCG conducted a geophysical survey using a ground penetrating radar and gradiometer. The findings from the data were used to determine and pinpoint areas of interest for subsequent excavation