Physics of Skiing: The Ideal-Carving Equation and Its Applications

Ideal carving occurs when a snowboarder or skier, equipped with a snowboard or carving skis, describes a perfect carved turn in which the edges of the ski alone, not the ski surface, describe the trajectory followed by the skier, without any slipping or skidding. In this article, we derive the "ideal-carving" equation which describes the physics of a carved turn under ideal conditions. The laws of Newtonian classical mechanics are applied. The parameters of the ideal-carving equation are the inclination of the ski slope, the acceleration of gravity, and the sidecut radius of the ski. The variables of the ideal-carving equation are the velocity of the skier, the angle between the trajectory of the skier and the horizontal, and the instantaneous curvature radius of the skier's trajectory. Relations between the slope inclination and the velocity range suited for nearly ideal carving are discussed, as well as implications for the design of carving skis and snowboards.Comment: 13 pages, 9 figures, LaTeX; to appear in Can. J. Phy

A review of digital forensics methods for JPEG file carving

Digital forensics is an important field of cybersecurity and digital crimes investigation. It entails applying file recovery methods to analyze data from storage media and extract hidden, deleted or overwritten files. The recovery process might have accompanied with cases of unallocated partitions of blocks or clusters and the absence of file system metadata. These cases entail advance recovery methods that have carving abilities. The file carving methods include different types of techniques to identify, validate and reassemble the file. This paper presents a comprehensive study of data recovery, file carving, and file reassembling. It focuses on identifying and recovering JPEG Images as it is a wildly covered in the literature. It classifies the carving techniques into three types: signature-, structure-, and content-based carvers. Subsequently, the paper reviews seven advanced carving methods in the literature. Finally, the paper presents a number of research gaps and conclude a number of possible improvements. Generally, both the gaps and possible improvements are associated with the fragmentation problem of data files

Carving Alaska Soapstone

Thesis (M.A.) University of Alaska Fairbanks, 196

Carving model-free inference

In many large-scale experiments, the investigator begins with pilot data to look for promising findings. As fresh data becomes available at a later point of time, or from a different source, she is left with the question of how to use the full data to infer for the selected findings. Compensating for the overoptimism from selection, carving permits a reuse of pilot data for valid inference. The principles of carving are quite appealing in practice: instead of throwing away the pilot samples, carving simply discards the information consumed at the time of selection. However, the theoretical justification for carving is strongly tied to parametric models, an example being the ubiquitous gaussian model. In this paper we develop asymptotic guarantees to substantiate the use of carving beyond gaussian generating models. In simulations and in an application on gene expression data, we find that carving delivers valid and tight confidence intervals in model-free settings.Comment: 50 pages, 2 figures, 7 Table

Contour Generator Points for Threshold Selection and a Novel Photo-Consistency Measure for Space Carving

Space carving has emerged as a powerful method for multiview scene reconstruction. Although a wide variety of methods have been proposed, the quality of the reconstruction remains highly-dependent on the photometric consistency measure, and the threshold used to carve away voxels. In this paper, we present a novel photo-consistency measure that is motivated by a multiset variant of the chamfer distance. The new measure is robust to high amounts of within-view color variance and also takes into account the projection angles of back-projected pixels. Another critical issue in space carving is the selection of the photo-consistency threshold used to determine what surface voxels are kept or carved away. In this paper, a reliable threshold selection technique is proposed that examines the photo-consistency values at contour generator points. Contour generators are points that lie on both the surface of the object and the visual hull. To determine the threshold, a percentile ranking of the photo-consistency values of these generator points is used. This improved technique is applicable to a wide variety of photo-consistency measures, including the new measure presented in this paper. Also presented in this paper is a method to choose between photo-consistency measures, and voxel array resolutions prior to carving using receiver operating characteristic (ROC) curves

Carving Out the Space of 4D CFTs

We introduce a new numerical algorithm based on semidefinite programming to efficiently compute bounds on operator dimensions, central charges, and OPE coefficients in 4D conformal and N=1 superconformal field theories. Using our algorithm, we dramatically improve previous bounds on a number of CFT quantities, particularly for theories with global symmetries. In the case of SO(4) or SU(2) symmetry, our bounds severely constrain models of conformal technicolor. In N=1 superconformal theories, we place strong bounds on dim(Phi*Phi), where Phi is a chiral operator. These bounds asymptote to the line dim(Phi*Phi) <= 2 dim(Phi) near dim(Phi) ~ 1, forbidding positive anomalous dimensions in this region. We also place novel upper and lower bounds on OPE coefficients of protected operators in the Phi x Phi OPE. Finally, we find examples of lower bounds on central charges and flavor current two-point functions that scale with the size of global symmetry representations. In the case of N=1 theories with an SU(N) flavor symmetry, our bounds on current two-point functions lie within an O(1) factor of the values realized in supersymmetric QCD in the conformal window.Comment: 60 pages, 22 figure

Structure

An exploration of ground’s connections to structure (joint-carving, naturalness). The notion of structure is often invoked in connection to ground, because grounding is understood to impose constraints on the ‘structure of reality’. There is another, technical sense of structure, sometimes captured with reference to the notion of ‘joint-carving’. Both of these senses of structure as well as their potential connections are discussed

Ship carvers in eighteenth- and nineteenth-century Britain

Vessel ornamentation has been practised for thousands of years and over a vast geographical area. Unsurprisingly, the type of carvings and their purpose vary considerably from place to place and their style, form and subject matter have changed significantly over time. This article focuses on the ship carvings of eighteenth- and nineteenth-century Britain, and more specifically it investigates those who produced them. Classified as neither sculptors nor shipbuilders, ship carvers in Britain, both in the past and in more recent times, have been denied the appreciation that their unique and specialized art deserves. This article addresses the apparent difficulty that exists in classifying ship carvers and the carvings they produced. By examining how the carvers were trained and how work was commissioned and executed, the article investigates how these carvers were perceived by their contemporaries and how they fit into the broader historical context of the period