Hadamard 2-(63,31,15) designs invariant under the dihedral group of order 10

AbstractAll Hadamard 2-(63,31,15) designs invariant under the dihedral group of order 10 are constructed and classified up to isomorphism together with related Hadamard matrices of order 64. Affine 2-(64,16,5) designs can be obtained from Hadamard 2-(63,31,15) designs having line spreads by Rahilly’s construction [A. Rahilly, On the line structure of designs, Discrete Math. 92 (1991) 291–303]. The parameter set 2-(64,16,5) is one of two known sets when there exists several nonisomorphic designs with the same parameters and p-rank as the design obtained from the points and subspaces of a given dimension in affine geometry AG(n,pm) (p a prime). It is established that an affine 2-(64,16,5) design of 2-rank 16 that is associated with a Hadamard 2-(63,31,15) design invariant under the dihedral group of order 10 is either isomorphic to the classical design of the points and hyperplanes in AG(3,4), or is one of the two exceptional designs found by Harada, Lam and Tonchev [M. Harada, C. Lam, V.D. Tonchev, Symmetric (4, 4)-nets and generalized Hadamard matrices over groups of order 4, Designs Codes Cryptogr. 34 (2005) 71–87]

Hybrid Structure of Stretchable Interconnect for Reliable E-skin Application

This paper presents the methodology for realisation of stretchable interconnects based on hybrid thin film stack of spray-coated conductive polymer PEDOT: PSS and evaporated gold (Au) film. The PEDOT: PSS film, with its properties in electrical conductivity and mechanical softness, serves as a stress release buffer in the layered hybrid structure. With the serpentine-shape design, the stretchable interconnects can accommodate larger deformation in comparison with a straight line. The correlation between interconnects' morphology (i.e. cracks propagation) with their electrical behaviour has been studied through microscope in along with electrical characterisation under external strain. Furthermore, a comparison in failure strain among different serpentine-shaped designs has been studied. Higher level in stretchability of interconnects can be achieved with a larger arc degree in design. The fabricated stretchable interconnects can accommodate significant deformations up to 72% external strain while maintaining electrically conductive

Design of a reusable kinetic energy absorber for an astronaut safety tether to be used during extravehicular activities on the Space Station

The goal of this project is to design a reusable safety device for a waist tether which will absorb the kinetic energy of an astronaut drifting away from the Space Station. The safety device must limit the tension of the tether line in order to prevent damage to the astronaut's space suit or to the structure of the spacecraft. The tether currently used on shuttle missions must be replaced after the safety feature has been developed. A reusable tether for the Space Station would eliminate the need for replacement tethers, conserving space and mass. This report presents background information, scope and limitations, methods of research and development, alternative designs, a final design solution and its evaluation, and recommendations for further work

Universality in block dependent linear models with applications to nonparametric regression

Over the past decade, characterizing the exact asymptotic risk of regularized estimators in high-dimensional regression has emerged as a popular line of work. This literature considers the proportional asymptotics framework, where the number of features and samples both diverge, at a rate proportional to each other. Substantial work in this area relies on Gaussianity assumptions on the observed covariates. Further, these studies often assume the design entries to be independent and identically distributed. Parallel research investigates the universality of these findings, revealing that results based on the i.i.d.~Gaussian assumption extend to a broad class of designs, such as i.i.d.~sub-Gaussians. However, universality results examining dependent covariates so far focused on correlation-based dependence or a highly structured form of dependence, as permitted by right rotationally invariant designs. In this paper, we break this barrier and study a dependence structure that in general falls outside the purview of these established classes. We seek to pin down the extent to which results based on i.i.d.~Gaussian assumptions persist. We identify a class of designs characterized by a block dependence structure that ensures the universality of i.i.d.~Gaussian-based results. We establish that the optimal values of the regularized empirical risk and the risk associated with convex regularized estimators, such as the Lasso and ridge, converge to the same limit under block dependent designs as they do for i.i.d.~Gaussian entry designs. Our dependence structure differs significantly from correlation-based dependence, and enables, for the first time, asymptotically exact risk characterization in prevalent nonparametric regression problems in high dimensions. Finally, we illustrate through experiments that this universality becomes evident quite early, even for relatively moderate sample sizes

Improved bend waveguide design for terahertz transmission

Bending waveguides with 90 corners based on a two-dimensional photonic crystal with metallic cylinders arranged in a square lattice are studied for THz wave guiding. Considering single- and double-line defects, five different designs are investigated and assessed in terms of their transmission performance. A better structure is proposed by increasing the number of rods in the bending arc, thus achieving superior performance of the transmission characteristics in comparison to that of the former five designs. A comparison of the improved bend waveguide with a linear wave-guide shows a significant reduction of the bending losses. Trans-mission levels of up to 98% within a 2.5 THz bandwidth (from 1.2 to 3.7 THz) have been accomplished

A practical method for optimised earth electrode designs at transmission towers exposed to lightning

A large percentage of transmission line outages in Malaysia are due to lightning activity with backflashover being the main cause. Previous investigations have indicated that tower footing earth resistance is one of the main factors in reducing the occurrence of backflashovers. The present studies review some of the tower earthing design options. From this standard designs are proposed together with a practical method of optimising the design based on soil resistivity measurement data. The process is presented via a procedure which includes the main measurement and design steps. This allows different standard designs to be selected to suit the type of soil structure at the site of the proposed transmission tower. Where measurements indicate a high resistivity layer with underlying low resistivity soil, an electrode design relying more on driven rods is used. Conversely, a design using more horizontal electrode would be selected where the soil structure is of low resistivity above high. Trial installations using the newly designed electrode arrangements have been conducted and preliminary results indicate significant improvements in lightning performance