Complete enumeration of two-Level orthogonal arrays of strength dd with d+2d+2 constraints

Enumerating nonisomorphic orthogonal arrays is an important, yet very difficult, problem. Although orthogonal arrays with a specified set of parameters have been enumerated in a number of cases, general results are extremely rare. In this paper, we provide a complete solution to enumerating nonisomorphic two-level orthogonal arrays of strength $d$ with $d+2$ constraints for any $d$ and any run size $n=\lambda2^d$. Our results not only give the number of nonisomorphic orthogonal arrays for given $d$ and $n$, but also provide a systematic way of explicitly constructing these arrays. Our approach to the problem is to make use of the recently developed theory of $J$-characteristics for fractional factorial designs. Besides the general theoretical results, the paper presents some results from applications of the theory to orthogonal arrays of strength two, three and four.Comment: Published at http://dx.doi.org/10.1214/009053606000001325 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Assessing Friction Characteristics of Liquid Lubricants

The decline of fossil fuel reserves and the increasing awareness of greenhouse gas emissions have been the primary driving forces behind the need to conserve energy. To improve fuel efficiency friction modifiers are commonly blended into lubricants. Reduction of friction will clearly lead to less energy requirements. However, an accurate evaluation of lubricant performance is not possible using existing test equipment. The main reason is that current test rigs require operating conditions that induce wear so that the measurement of friction in these rigs is not a real evaluation of friction. The paper will detail the design and commissioning of a purpose built test rig to measure frictional characteristics of various oils as well as the results of the tests performed

THz Repetition Frequency Mode-Locked Laser Using Novel Sampled Gratings

Conventional sampled grating distributed-Bragg-gratings (C-SGDBRs) are widely used in tunable DBR lasers [1], and more recently have been used to precisely control the wavelength spacing in arrays of DBR lasers for use in WDM systems [2], and as the reflectors in THz repetition frequency (Fr) semiconductor mode locked lasers (SMLLs) [3]. However, the effective coupling coefficient, κ, of a C-SGDBR (Fig. 1(a)) is necessarily reduced substantially from that of a uniform grating because much of the sampled grating period has no grating. Here, for the first time, we apply a combination of π-phase shifted gratings, previously demonstrated in fiber lasers [4], with the C-SGDBR technique to THz repetition frequency SMLLs. Using a single electron beam lithography (EBL) step we have demonstrated a 620 GHz side-wall SGDBR MLL with an increased effective κ

Integrated Phase-locked Laser Diodes at 1.55μm

Two types of integrated phased locked laser diodes operating at 1.55 μm were demonstrated, using either a distributed feedback laser seeding source or a self-locking multi-mode interference array. Both exhibited far field patterns that reflected mutual coherence between the light from the output waveguides

U.S. GRAPEFRUIT EXPORTS AND JAPANESE TRADE RESTRICTIONS

International Relations/Trade,