Computational Solution Of Inverse Problems With Simulated Annealing

The examination of inverse problems represents a fascinating, diverse and difficult area of study. Almost any problem in mathematics, physics and engineering has an associated inverse problem. The method of quasi-solutions allows one to reformulate inverse problems as a function minimization involving the associated forward problem. The function to minimize is known as a penalty function or cost function and is defined as the least squares difference between some measured quantity and a quantity computed by the forward solver. This strategy avoids the need to construct the inverse operator. The forward problem is often well posed and can be solved quickly and accurately by various numerical solution techniques. The cost function, however, is typically a complicated multidimensional, multimodal surface. These properties make it difficult to locate the global minimum where the quasi-solution exists.;The simulated annealing algorithm performs well at minimizing functions with multiple local minima and hence has been employed in the quasi-solution of the inverse problem. Regularization techniques in the area of inverse problems attempt to better condition the problem by removing the local minimum from the cost function. Focus in this work has been placed on finding the global minimum of the multimodal cost function rather than strongly regularizing the penalty function. Two physical applications are chosen to test the feasibility of the proposed inversion method.;The first application involves the mise-a-la-masse electromagnetic prospecting technique from geophysics. This technique attempts to recover the size, shape and orientation of buried conductive ore bodies based on surface measurements. Here, a finite difference method is employed to solve the potential equation in a 3D semi-infinite medium.;The second application focuses on the scattering of acoustic waves by a 2D inhomogeneous medium. In this field, acoustic waves scattered from incident waves are used to reconstruct the index of refraction of the inhomogeneity. The incident waves are time harmonic plane waves which lie in the resonance region. A special hybrid partial differential equation/integral equation solution technique is employed to solve the direct problem

Superconducting Films for Absorber-Coupled MKID Detectors for Sub-Millimeter and Far-Infrared Astronomy

We describe measurements of the properties, at dc, gigahertz, and terahertz frequencies, of thin (10 nm) aluminum films with 10 ohm/{rm square}$ normal state sheet resistance. Such films can be applied to construct microwave kinetic inductance detector arrays for submillimeter and far-infrared astronomical applications in which incident power excites quasiparticles directly in a superconducting resonator that is configured to present a matched-impedance to the high frequency radiation being detected. For films 10 nm thick, we report normal state sheet resistance, resistance-temperature curves for the superconducting transition, quality factor and kinetic inductance fraction for microwave resonators made from patterned films, and terahertz measurements of sheet impedance measured with a Fourier Transform Spectrometer. We compare properties with similar resonators made from niobium 600 nm thick

Digital play and the actualisation of the consumer imagination

In this article, the authors consider emerging consumer practices in digital virtual spaces. Building on constructions of consumer behavior as both a sense-making activity and a resource for the construction of daydreams, as well as anthropological readings of performance, the authors speculate that many performances during digital play are products of consumer fantasy. The authors develop an interpretation of the relationship between the real and the virtual that is better equipped to understand the movement between consumer daydreams and those practices actualized in the material and now also in digital virtual reality. The authors argue that digital virtual performances present opportunities for liminoid transformations through inversions, speculations, and playfulness acted out in aesthetic dramas. To illustrate, the authors consider specific examples of the theatrical productions available to consumers in digital spaces, highlighting the consumer imagination that feeds them, the performances they produce, and the potential for transformation in consumer-players

Changing practice in dementia care in the community: developing and testing evidence-based interventions, from timely diagnosis to end of life (EVIDEM)

Background Dementia has an enormous impact on the lives of individuals and families, and on health and social services, and this will increase as the population ages. The needs of people with dementia and their carers for information and support are inadequately addressed at all key points in the illness trajectory. Methods The Unit is working specifically on an evaluation of the impact of the Mental Capacity Act 2005, and will develop practice guidance to enhance concordance with the Act. Phase One of the study has involved baseline interviews with practitioners across a wide range of services to establish knowledge and expectations of the Act, and to consider change processes when new policy and legislation are implemented. Findings Phase 1, involving baseline interviews with 115 practitioners, identified variable knowledge and understanding about the principles of the Act. Phase 2 is exploring everyday decision-making by people with memory problems and their carers

Origins Space Telescope science drivers to design traceability

The Origins Space Telescope (Origins) concept is designed to investigate the creation and dispersal of elements essential to life, the formation of planetary systems, and the transport of water to habitable worlds and the atmospheres of exoplanets around nearby K- and M-dwarfs to identify potentially habitable—and even inhabited—worlds. These science priorities are aligned with NASA’s three major astrophysics science goals: How does the Universe work? How did we get here? and Are we alone? We briefly describe the science case that arose from the astronomical community and the science traceability matrix for Origins. The science traceability matrix prescribes the design of Origins and demonstrates that it will address the key science questions motivated by the science case

Denunciation, blame and the moral turn in public life

Public denunciations involve ritual destruction of the moral standing of the target. They are intimately related to the assigning of blame and to the alleged perpetrator’s concomitant denial of wrongdoing. While public denunciations are not a new phenomenon, what has arguably changed in recent years is the loosening of strictures on publicly denouncing immoral behavior, even when (alleged) moral transgressions happen within the remit of traditionally conceived intimate or private relationships, and the broadening of what counts as a public figure. The aim of this paper is to interrogate this moral turn in public life by examining how public denunciations are accomplished in broadcast talk, and the role they play in co-constructing and reaffirming perceived common moral ground. We conclude that while moral criticisms, such as accusing, blaming, denouncing, reproaching, and so on, are evidently oriented as sensitive actions in the public sphere, it appears that constraints on publicly denouncing immoral behavior are on the wane

Toward Large FOV High-Resolution X-Ray Imaging Spectrometer: Microwave Multiplexed Readout of 32 TES Microcalorimeters

We performed a small-scale demonstration at GSFC of high-resolution x-ray TES microcalorimeters read out using a microwave SQUID multiplexer. This work is part of our effort to develop detector and readout technologies for future space based x-ray instruments such as the microcalorimeter spectrometer envisaged for Lynx, a large mission concept under development for the Astro 2020 Decadal Survey. In this paper we describe our experiment, including details of a recently designed, microwave-optimized low-temperature setup that is thermally anchored to the 50 mK stage of our laboratory ADR. Using a ROACH2 FPGA at room temperature, we simultaneously read out 32 pixels of a GSFC-built detector array via a NIST-built multiplexer chip with Nb coplanar waveguide resonators coupled to RF SQUIDs. The resonators are spaced 6 MHz apart (at approx. 5.9 GHz) and have quality factors of approximately 15,000. Using flux-ramp modulation frequencies of 160 kHz we have achieved spectral resolutions of 3 eV FWHM on each pixel at 6 keV. We will present the measured system-level noise and maximum slew rates, and briefly describe the implications for future detector and readout design

Rethinking the changing structures of rural local government - state power, rural politics and local political strategies?

Copyright © 2010 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Molecular and Biochemical Parasitology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Rural Studies, 2010, Vol. 26, Issue 3, pp 272–283 DOI: http://dx.doi.org/10.1016/j.jrurstud.2009.12.005There is a notable absence in contemporary rural studies - of both a theoretical and empirical nature - concerning the changing nature of rural local government. Despite the scale and significance of successive rounds of local government reorganisation in the UK, very little has been written on this topic from a rural perspective. Instead research on local political change has tended to concentrate on local governance and local partnerships – on the extra-governmental aspects of the governance system – rather than on local government itself. In contrast, this paper draws upon strategic relational state theory to explore the changing structures and institutions of rural local government, and analyse how these can be related to the changing state strategies of those groups which are politically powerful in rural areas. In this respect, the paper draws on current and previous rounds of local government reorganisation to illustrate how new objects of governance, new state strategies and new hegemonic projects are emerging as a consequence of such restructuring processes