17,590 research outputs found

    Economic Analysis in the Pacific Northwest Land Resources Project: Theoretical Considerations and Preliminary Results

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    The Pacific Northwest Land Resources Inventory Demonstration Project i s an a ttempt to combine a whole spectrum of heterogeneous geographic, institutional and applications elements in a synergistic approach to the evaluation of remote sensing techniques. This diversity is the prime motivating factor behind a theoretical investigation of alternative economic analysis procedures. For a multitude of reasons--simplicity, ease of understanding, financial constraints and credibility, among others--cost-effectiveness emerges as the most practical tool for conducting such evaluation determinatIons in the Pacific Northwest. Preliminary findings in two water resource application areas suggest, in conformity with most published studies, that Lands at-aided data collection methods enjoy substantial cost advantages over alternative techniques. The pntential for sensitivity analysis based on cost/accuracy tradeoffs is considered on a theoretical plane in the absence of current accuracy figures concerning the Landsat-aided approach

    A Hybrid Observer for a Distributed Linear System with a Changing Neighbor Graph

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    A hybrid observer is described for estimating the state of an m>0m>0 channel, nn-dimensional, continuous-time, distributed linear system of the form x˙=Ax,  yi=Cix,  i{1,2,,m}\dot{x} = Ax,\;y_i = C_ix,\;i\in\{1,2,\ldots, m\}. The system's state xx is simultaneously estimated by mm agents assuming each agent ii senses yiy_i and receives appropriately defined data from each of its current neighbors. Neighbor relations are characterized by a time-varying directed graph N(t)\mathbb{N}(t) whose vertices correspond to agents and whose arcs depict neighbor relations. Agent ii updates its estimate xix_i of xx at "event times" t1,t2,t_1,t_2,\ldots using a local observer and a local parameter estimator. The local observer is a continuous time linear system whose input is yiy_i and whose output wiw_i is an asymptotically correct estimate of LixL_ix where LiL_i a matrix with kernel equaling the unobservable space of (Ci,A)(C_i,A). The local parameter estimator is a recursive algorithm designed to estimate, prior to each event time tjt_j, a constant parameter pjp_j which satisfies the linear equations wk(tjτ)=Lkpj+μk(tjτ),  k{1,2,,m}w_k(t_j-\tau) = L_kp_j+\mu_k(t_j-\tau),\;k\in\{1,2,\ldots,m\}, where τ\tau is a small positive constant and μk\mu_k is the state estimation error of local observer kk. Agent ii accomplishes this by iterating its parameter estimator state ziz_i, qq times within the interval [tjτ,tj)[t_j-\tau, t_j), and by making use of the state of each of its neighbors' parameter estimators at each iteration. The updated value of xix_i at event time tjt_j is then xi(tj)=eAτzi(q)x_i(t_j) = e^{A\tau}z_i(q). Subject to the assumptions that (i) the neighbor graph N(t)\mathbb{N}(t) is strongly connected for all time, (ii) the system whose state is to be estimated is jointly observable, (iii) qq is sufficiently large, it is shown that each estimate xix_i converges to xx exponentially fast as tt\rightarrow \infty at a rate which can be controlled.Comment: 7 pages, the 56th IEEE Conference on Decision and Contro

    Avoiding Irrational NeuroLaw Exuberance: A Plea for Neuromodesty

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    In a 2002 editorial published in The Economist, the following warning was given: Genetics may yet threaten privacy, kill autonomy, make society homogeneous and gut the concept of human nature. But neuroscience could do all of these things first. The genome was fully sequenced in 2001, and there has not been one resulting major advance in therapeutic medicine since. Thus, even in its most natural applied domain-medicine-genetics has not had the far-reaching consequences that were envisioned. The same has been true for various other sciences that were predicted to revolutionize the law, including behavioral psychology, sociology, psychodynamic psychology, and others. This will also be true of neuroscience, which is simply the newest science on the block. Neuroscience is not going to do the terrible things The Economist fears, at least not for the foreseeable future. Neuroscience has many things to say but not nearly as much as people would hope, especially in relation to law. At most, in the near to intermediate term, neuroscience may make modest contributions to legal policy and case adjudication. Nonetheless, there has been irrational exuberance about the potential contribution of neuroscience, an issue I have addressed previously and referred to as Brain Overclaim Syndrome. I first consider the law\u27s motivation and the motivation of some advocates to turn to science to solve the very hard normative problems that law addresses. Part III discusses the law\u27s psychology and its concepts of the person and responsibility. The next Part considers the general relation of neuroscience to law, which I characterize as the issue of translation. Part V canvasses various distractions that have bedeviled clear thinking about the relation of scientific, causal accounts of behavior to responsibility. The following Part examines the limits of neurolaw and Part VII considers why neurolaw does not pose a genuinely radical challenge to the law\u27s concepts of the person and responsibility. Part VIII makes a case for cautious optimism about the contribution neuroscience may make to law in the near and intermediate term. A brief conclusion follows..

    Quantized Non-Abelian Monopoles on S^3

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    A possible electric-magnetic duality suggests that the confinement of non-Abelian electric charges manifests itself as a perturbative quantum effect for the dual magnetic charges. Motivated by this possibility, we study vacuum fluctuations around a non-Abelian monopole-antimonopole pair treated as point objects with charges g=\pm n/2 (n=1,2,...), and placed on the antipodes of a three sphere of radius R. We explicitly find all the fluctuation modes by linearizing and solving the Yang-Mills equations about this background field on a three sphere. We recover, generalize and extend earlier results, including those on the stability analysis of non-Abelian magnetic monopoles. We find that for g \ge 1 monopoles there is an unstable mode that tends to squeeze magnetic flux in the angular directions. We sum the vacuum energy contributions of the fluctuation modes for the g=1/2 case and find oscillatory dependence on the cutoff scale. Subject to certain assumptions, we find that the contribution of the fluctuation modes to the quantum zero point energy behaves as -R^{-2/3} and hence decays more slowly than the classical -R^{-1} Coulomb potential for large R. However, this correction to the zero point energy does not agree with the linear growth expected if the monopoles are confined.Comment: 18 pages, 5 figures. Minor changes, reference list update

    Resonance modes in a 1D medium with two purely resistive boundaries: calculation methods, orthogonality and completeness

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    Studying the problem of wave propagation in media with resistive boundaries can be made by searching for "resonance modes" or free oscillations regimes. In the present article, a simple case is investigated, which allows one to enlighten the respective interest of different, classical methods, some of them being rather delicate. This case is the 1D propagation in a homogeneous medium having two purely resistive terminations, the calculation of the Green function being done without any approximation using three methods. The first one is the straightforward use of the closed-form solution in the frequency domain and the residue calculus. Then the method of separation of variables (space and time) leads to a solution depending on the initial conditions. The question of the orthogonality and completeness of the complex-valued resonance modes is investigated, leading to the expression of a particular scalar product. The last method is the expansion in biorthogonal modes in the frequency domain, the modes having eigenfrequencies depending on the frequency. Results of the three methods generalize or/and correct some results already existing in the literature, and exhibit the particular difficulty of the treatment of the constant mode

    Ion Trap Mass Spectrometers for Identity, Abundance and Behavior of Volatiles on the Moon

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    NASA GSFC and The Open University (UK) are collaborating to deploy an Ion Trap Mass Spectrometer on the Moon to investigate the lunar water cycle. The ITMS is flight-proven throughthe Rosetta Philae comet lander mission. It is also being developed under ESA funding to analyse samples drilled from beneath the lunar surface on the Roscosmos Luna-27 lander (2025).Now, GSFC and OU will now develop a compact ITMS instrument to study the near-surface lunar exosphere on board a CLPS Astrobotic lander at Lacus Mortis in 2021

    Accurate Transfer Maps for Realistic Beamline Elements: Part I, Straight Elements

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    The behavior of orbits in charged-particle beam transport systems, including both linear and circular accelerators as well as final focus sections and spectrometers, can depend sensitively on nonlinear fringe-field and high-order-multipole effects in the various beam-line elements. The inclusion of these effects requires a detailed and realistic model of the interior and fringe fields, including their high spatial derivatives. A collection of surface fitting methods has been developed for extracting this information accurately from 3-dimensional field data on a grid, as provided by various 3-dimensional finite-element field codes. Based on these realistic field models, Lie or other methods may be used to compute accurate design orbits and accurate transfer maps about these orbits. Part I of this work presents a treatment of straight-axis magnetic elements, while Part II will treat bending dipoles with large sagitta. An exactly-soluble but numerically challenging model field is used to provide a rigorous collection of performance benchmarks.Comment: Accepted to PRST-AB. Changes: minor figure modifications, reference added, typos corrected

    Resonant transmission of light through finite chains of subwavelength holes

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    In this paper we show that the extraordinary optical transmission phenomenon found before in 2D hole arrays is already present in a linear chain of subwavelength holes, which can be considered as the basic geometrical unit showing this property. In order to study this problem we have developed a new theoretical framework, able to analyze the optical properties of finite collections of subwavelength apertures and/or dimples (of any shape and placed in arbitrary positions) drilled in a metallic film.Comment: Accepted for publication in Phys. Rev. Let
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