Polarimetric Control of Reflective Metasurfaces

This letter addresses the synthesis of reflective cells approaching a given desired Floquet's scattering matrix. This work is motivated by the need to obtain much finer control of reflective metasurfaces by controlling not only their co-polarized reflection but also their cross-coupling behavior. The demonstrated capability will enable more powerful design approaches -involving all field components in phase and magnitude- and consequently better performance in applications involving reflective metasurfaces. We first expose some fundamental theoretical constraints on the cell scattering parameters. Then, a successful procedure for controlling all four scattering parameters by applying parallelogram and trapezoid transformations to square patches is presented, considering both normal and oblique incidence

Experiences in involving analysts in visualisation design

Involving analysts in visualisation design has obvious benefits, but the knowledge-gap between domain experts ("analysts") and visualisation designers ("designers") often makes the degree of their involvement fall short of that aspired. By promoting a culture of mutual learning, understanding and contribution between both analysts and designers from the outset, participants can be raised to a level at which all can usefully contribute to both requirement definition and design. We describe the process we use to do this for tightly-scoped and short design exercises -- with meetings/workshops, iterative bursts of design/prototyping over relatively short periods of time, and workplace-based evaluation -- illustrating this with examples of our own experience from recent work with bird ecologists

A record of the design process A systematic investigation of the role, value, and effectiveness of the “process book” for interior design students

The aim of this study is to analyze the structure, role, and effectiveness of a design student's "process book" as a method of capturing and facilitating design thinking. The "process book" includes all of the work completed during a design project such as written notes, drawings, and research. This study poses the following research questions: 1) What role and value does the process book have to design students and instructors? 2) How can the process book structure help to reduce a student’s cognitive load, yet allow for the spontaneous actions involved in graphic thinking? This mixed-method research study includes an analysis and exploration of interior design student and instructor perspectives of the process book artifact and tool. The data collection and analysis involves two main components. The first includes an investigation of student and faculty perspectives of the structure, role, and effectivenss of the process book obtained from semi-structured interviews. The second part is an online student survey questionnaire of sophomore, junior, senior, and graduate student perspectives. One interior design program in a large Midwestern university was selected. All students within the undergraduate and graduate program were invited to participate in the survey questionnaire and all faculty were interviewed. Interviews were audio-taped and later transcribed for coding and interpretation. This study serves as a case study and pilot study to provide a foundation for a larger-scale future research initiative. Results from this study will inform two future initiatives: 1) design of a larger-scale research design involving a multi-university sampling frame, and 2) development of a “digital process book” research study. Keywords: Design Process, Design Education, Drawing Research</p

Optimal designs for rational function regression

We consider optimal non-sequential designs for a large class of (linear and nonlinear) regression models involving polynomials and rational functions with heteroscedastic noise also given by a polynomial or rational weight function. The proposed method treats D-, E-, A-, and $\Phi_p$-optimal designs in a unified manner, and generates a polynomial whose zeros are the support points of the optimal approximate design, generalizing a number of previously known results of the same flavor. The method is based on a mathematical optimization model that can incorporate various criteria of optimality and can be solved efficiently by well established numerical optimization methods. In contrast to previous optimization-based methods proposed for similar design problems, it also has theoretical guarantee of its algorithmic efficiency; in fact, the running times of all numerical examples considered in the paper are negligible. The stability of the method is demonstrated in an example involving high degree polynomials. After discussing linear models, applications for finding locally optimal designs for nonlinear regression models involving rational functions are presented, then extensions to robust regression designs, and trigonometric regression are shown. As a corollary, an upper bound on the size of the support set of the minimally-supported optimal designs is also found. The method is of considerable practical importance, with the potential for instance to impact design software development. Further study of the optimality conditions of the main optimization model might also yield new theoretical insights.Comment: 25 pages. Previous version updated with more details in the theory and additional example

Electromagnetic wave diffraction by periodic planar metamaterials with nonlinear constituents

We present a theory which explains how to achieve an enhancement of nonlinear effects in a thin layer of nonlinear medium by involving a planar periodic structure specially designed to bear a trapped-mode resonant regime. In particular, the possibility of a nonlinear thin metamaterial to produce the bistable response at a relatively low input intensity due to a large quality factor of the trapped-mode resonance is shown. Also a simple design of an all-dielectric low-loss silicon-based planar metamaterial which can provide an extremely sharp resonant reflection and transmission is proposed. The designed metamaterial is envisioned for aggregating with a pumped active medium to achieve an enhancement of quantum dots luminescence and to produce an all-dielectric analog of a 'lasing spaser'.Comment: 18 pages, 13 figure

Virtual and rapid prototyping of an underactuated space end effector

A fast and reliable verification of an initial concept is an important need in the field of mechatronics. Usually, the steps for a successful design require multiple iterations involving a sequence of design phases-the initial one and several improvements-and the tests of the resulting prototypes, in a trial and error scheme. Now a day’s software and hardware tools allow for a faster approach, in which the iterations between design and prototyping are by far reduced, even to just one in favorable situation. This work presents the design, manufacturing and testing of a robotic end effector for space applications, realized through virtual prototyping, followed by rapid prototyping realization. The first process allows realizing a mathematical model of the robotic system that, once all the simulations confirm the effectiveness of the design, can be directly used for the rapid prototyping by means of 3D printing. The workflow and the results of the process are described in detail in this paper, showing the qualitative and quantitative evaluation of the performance of both the virtual end effector and the actual physical robotic hand

Designing Water Markets to Manage Coupled Externalities: An Application to Irrigation-Induced Salinity in Australia

In this paper, the design of water markets for the management of irrigation-induced salinity in Australia is addressed. Indeed, this setting exhibits complex interactions between the different features of the resource water. Quality, quantity of surface and ground-water interact in ways that produce coupled environmental externalities. It is then difficult to design efficient policy instruments to tackle all the issues at stake. This paper provides a preliminary analysis of three types of water market mechanisms, involving diversion rights and recharge rights.water markets, irrigation induced salinity, Australia, externalities, policy instruments, Resource /Energy Economics and Policy, Q25, Q53,

A fractional representation approach to the robust regulation problem for MIMO systems

The aim of this paper is in developing unifying frequency domain theory for robust regulation of MIMO systems. The main theoretical results achieved are a new formulation of the internal model principle, solvability conditions for the robust regulation problem, and a parametrization of all robustly regulating controllers. The main results are formulated with minimal assumptions and without using coprime factorizations thus guaranteeing applicability with a very general class of systems. In addition to theoretical results, the design of robust controllers is addressed. The results are illustrated by two examples involving a delay and a heat equation.Comment: 23 pages, 3 figures, submitted to International Journal of Robust and Nonlinear Contro