Testing surface area with arbitrary accuracy

Recently, Kothari et al.\ gave an algorithm for testing the surface area of an arbitrary set $A \subset [0, 1]^n$. Specifically, they gave a randomized algorithm such that if $A$'s surface area is less than $S$ then the algorithm will accept with high probability, and if the algorithm accepts with high probability then there is some perturbation of $A$ with surface area at most $\kappa_n S$. Here, $\kappa_n$ is a dimension-dependent constant which is strictly larger than 1 if $n \ge 2$, and grows to $4/\pi$ as $n \to \infty$. We give an improved analysis of Kothari et al.'s algorithm. In doing so, we replace the constant $\kappa_n$ with $1 + \eta$ for $\eta > 0$ arbitrary. We also extend the algorithm to more general measures on Riemannian manifolds.Comment: 5 page

A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam

A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This new SBN Program will deliver a rich and compelling physics opportunity, including the ability to resolve a class of experimental anomalies in neutrino physics and to perform the most sensitive search to date for sterile neutrinos at the eV mass-scale through both appearance and disappearance oscillation channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we estimate that a search for muon neutrino to electron neutrino appearance can be performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter region. In this proposal for the SBN Program, we describe the physics analysis, the conceptual design of the LAr1-ND detector, the design and refurbishment of the T600 detector, the necessary infrastructure required to execute the program, and a possible reconfiguration of the BNB target and horn system to improve its performance for oscillation searches.Comment: 209 pages, 129 figure

A multimodal neuroimaging study of somatosensory system

The thesis is the result of a training by the Magnetoencephalography (MEG)-lab by the Center mind/brain science of the university of Trento. Final goal of the analysis was answering the question if MEG is capable to capture activities from the subcortical brain areas and to follow the neural information flow up along the fibers to the cortex. First aim of the thesis is describing the project and developing of an experiment on the somatosensory system that I executed by the CIMeC. The somatosensory system was activated by applying electrical stimulation to the median nerve and MEG signal during this stimulation was recorded. Also MRI and diffusion MRI data of the subject were collected. Further aim of the thesis is to describe the analysis I executed on the collected data. For this purpose the MEG source localization was executed and also Monte-Carlo simulation. The data obtained were integrated with the information obtained from diffusion MRI. Satisfactory results were obtained although we could not prove definitely the result

Uncertainty estimation of shape and roughness measurement

One of the most common techniques to measure a surface or form is mechanical probing. Although used since the early 30s of the 20th century, a method to calculate a task specific uncertainty budget was not yet devised. Guidelines and statistical estimates are common in certain cases but an unambiguous method for all kinds of measurements and measurement tasks is absent.Anew method, the virtual measurement machine, already successfully implemented in CMMs, is now applied on a specific group of stylus measurement instruments namely for: • roughness; • roundness; • contracers (form measurement). Each of these types of machines use the same measurement principle; a stylus is pressed against the object with a well specified force, moved across the object and the trajectory of the stylus tip is registered. The measurement process and its disturbances can be described theoretically and mathematically. Each disturbance or influencing factor which contributes to the uncertainty of the measurement is modeled and with this model simulated (virtual) measurements are generated. The virtual measurement depends upon the magnitude and range of the influencing factor. Some examples of influencing factors are; tip geometry, measurement force, probe gain factors, squareness of measurement axes, etc... The sensitivity of each factor upon the measurement is calculated with so-called virtual measurements. Recalculation of the describing parameters of the measured object with the virtual measurements gives the amount of uncertainty attributed to the influencing factor or machine parameter. The total uncertainty budget is composed out of each contribution in uncertainty of each machine parameter. The method is successfully implemented on two machines: the SV 624-3D (roughness and shape) and theRA2000 (roundness, form and cylindricity). It is shown that an on-line uncertainty budget can be calculated specifying each contributor. As not only gain factors need to be calibrated, but more input variables, e.g. calibration data of machine parameters, are required by the uncertainty calculation, calibration artefacts are developed to perform such a task. The artefacts can be used to perform a total and fast calibration on the shopfloor directly traceable to the appropriate primary standard. Combining the virtual measurement machine, implemented for roughness, roundness and form in high quality software, with the calibration artefacts, a powerful measurement tool is realised which allows to calculate a task specific uncertainty budget for these types of machines and creates a traceable measurement result which can be accredited by accreditation organizations

Computer simulations of realistic three-dimensional microstructures

A novel and efficient methodology is developed for computer simulations of realistic two-dimensional (2D) and three-dimensional (3D) microstructures. The simulations incorporate realistic 2D and 3D complex morphologies/shapes, spatial patterns, anisotropy, volume fractions, and size distributions of the microstructural features statistically similar to those in the corresponding real microstructures. The methodology permits simulations of sufficiently large 2D as well as 3D microstructural windows that incorporate short-range (on the order of particle/feature size) as well as long-range (hundred times the particle/feature size) microstructural heterogeneities and spatial patterns at high resolution. The utility of the technique has been successfully demonstrated through its application to the 2D microstructures of the constituent particles in wrought Al-alloys, the 3D microstructure of discontinuously reinforced Al-alloy (DRA) composites containing SiC particles that have complex 3D shapes/morphologies and spatial clustering, and 3D microstructure of boron modified Ti-6Al-4V composites containing fine TiB whiskers and coarse primary TiB particles. The simulation parameters are correlated with the materials processing parameters (such as composition, particle size ratio, extrusion ratio, extrusion temperature, etc.), which enables the simulations of rational virtual 3D microstructures for the parametric studies on microstructure-properties relationships. The simulated microstructures have been implemented in the 3D finite-elements (FE)-based framework for simulations of micro-mechanical response and stress-strain curves. Finally, a new unbiased and assumption free dual-scale virtual cycloids probe for estimating surface area of 3D objects constructed by 2D serial section images is also presented.Ph.D.Committee Chair: Arun M. Gokhale; Committee Member: David Frost; Committee Member: Meilin Liu; Committee Member: Burton R Patterson; Committee Member: Min Zho

A facility to Search for Hidden Particles (SHiP) at the CERN SPS

A new general purpose fixed target facility is proposed at the CERN SPS accelerator which is aimed at exploring the domain of hidden particles and make measurements with tau neutrinos. Hidden particles are predicted by a large number of models beyond the Standard Model. The high intensity of the SPS 400~GeV beam allows probing a wide variety of models containing light long-lived exotic particles with masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. The experimental programme of the proposed facility is capable of being extended in the future, e.g. to include direct searches for Dark Matter and Lepton Flavour Violation.Comment: Technical Proposa

Free Discontinuity Design: With an Application to the Economic Effects of Internet Shutdowns

Thresholds in treatment assignments can produce discontinuities in outcomes, revealing causal insights. In many contexts, like geographic settings, these thresholds are unknown and multivariate. We propose a non-parametric method to estimate the resulting discontinuities by segmenting the regression surface into smooth and discontinuous parts. This estimator uses a convex relaxation of the Mumford-Shah functional, for which we establish identification and convergence. Using our method, we estimate that an internet shutdown in India resulted in a reduction of economic activity by over 50%, greatly surpassing previous estimates and shedding new light on the true cost of such shutdowns for digital economies globally.Comment: 29 pages, 7 figures; authors listed alphabetically; code available at https://github.com/Davidvandijcke/fd