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71.
Frequency shift filtering technique 总被引:1,自引:0,他引:1
A heterodyne continuous time active filter is described. Control over the operating has been achieved without external components, through a tunable local oscillator. It has been possible to build a single chip filter that may be tuned from very low frequencies up to 70 kHz in a single range 相似文献
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Multiplicative updates for nonnegative quadratic programming 总被引:3,自引:0,他引:3
Many problems in neural computation and statistical learning involve optimizations with nonnegativity constraints. In this article, we study convex problems in quadratic programming where the optimization is confined to an axis-aligned region in the nonnegative orthant. For these problems, we derive multiplicative updates that improve the value of the objective function at each iteration and converge monotonically to the global minimum. The updates have a simple closed form and do not involve any heuristics or free parameters that must be tuned to ensure convergence. Despite their simplicity, they differ strikingly in form from other multiplicative updates used in machine learning. We provide complete proofs of convergence for these updates and describe their application to problems in signal processing and pattern recognition. 相似文献
77.
Saul Fisher 《Journal of Architectural Education》2000,54(1):35-44
Architecture programs should include a curriculum on philosophy of architecture in the analytic philosophical tradition. I describe such a curriculum and distinguish it from both the typical architectural theory curriculum and the typical philosophical aesthetics courses. Without such a curriculum, students likely lack exposure to the philosophical approach to aesthetics that is dominant in American universities. 相似文献
78.
Penner Louis A.; Shiffman Saul; Paty Jean A.; Fritzsche Barbara A. 《Canadian Metallurgical Quarterly》1994,66(4):712
The experience sampling method and palm-top computers were used to obtain 75–200 randomly timed in situ assessments of 11 mood-related items from 54 Ss over 12–24 days. The variability in the distribution of an S's responses to each item was used as an estimate of intrasubject mood variability. Mood variability was stable across time and across situations. The intercorrelations among the individual item variabilities were also substantial; when the items were combined into a mood variability scale, the coefficient alpha was .84. The stability and internal consistency of mood variability could not be reasonably attributed to similarity in item valences, differences among the Ss in the situations they encountered, response biases, or response errors. It was concluded that mood variability is a stable personal characteristic, but additional analyses suggested that it may be independent from other kinds of intraperson variability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
79.
Ryan A. Jacobson Robert F. Keefe Alistair M.S. Smith Scott Metlen Darin A. Saul Soren M. Newman Tamara J. Laninga Daniel Inman 《Biofuels, Bioproducts and Biorefining》2016,10(5):560-575
The alternative energy sector is expanding quickly in the USA since passage of the Energy Policy Act of 2005 and the Energy Independence and Security Act of 2007. Increased interest in wood‐based bioenergy has led to the need for robust modeling methods to analyze woody biomass operations at landscape scales. However, analyzing woody biomass operations in regions like the US Inland Northwest is difficult due to highly variable terrain and wood characteristics. We developed the Forest Residue Economic Assessment Model (FREAM) to better integrate with Geographical Information Systems and overcome analytical modeling limitations. FREAM analyzes wood‐based bioenergy logistics systems and provides a modeling platform that can be readily modified to analyze additional study locations. We evaluated three scenarios to test the FREAM’s utility: a local‐scale scenario in which a catalytic pyrolysis process produces gasoline from 181 437 Mg yr−1 of forest residues, a regional‐scale scenario that assumes a biochemical process to create aviation fuel from 725 748 Mg yr−1 of forest residues, and an international scenario that assumes a pellet mill producing pellets for international markets from 272 155 Mg yr−1 of forest residues. The local scenario produced gasoline for a modeled cost of $22.33 GJ−1*, the regional scenario produced aviation fuel for a modeled cost of $35.83 GJ−1 and the international scenario produced pellets for a modeled cost of $10.51 GJ−1. Results show that incorporating input from knowledgeable stakeholders in the designing of a model yields positive results. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd 相似文献
80.
Eukaryotic organisms such as plants are unable to utilise nitrogen gas (N2) directly as a source of this essential element and are dependent either on its biological conversion to ammonium by diazotrophic prokaryotes, or its supply as chemically synthesised nitrate fertiliser. The idea of genetically engineering crops with the capacity to fix N2 by introduction of the bacterial nitrogenase enzyme has long been discussed. However, the expression of an active nitrogenase must overcome several major challenges: the coordinated expression of multiple genes to assemble an enzyme complex containing several different metal cluster co-factors; the supply of sufficient ATP and reductant to the enzyme; the enzyme’s sensitivity to oxygen; and the intracellular accumulation of ammonium. The chloroplast of plant cells represents an attractive location for nitrogenase expression, but engineering the organelle’s genome is not yet feasible in most crop species. However, the unicellular green alga Chlamydomonas reinhardtii represents a simple model for photosynthetic eukaryotes with a genetically tractable chloroplast. In this review, we discuss the main advantages, and limitations, of this microalga as a testbed for producing such a complex multi-subunit enzyme. Furthermore, we suggest that a minimal set of six transgenes are necessary for chloroplast-localised synthesis of an ‘Fe-only’ nitrogenase, and from this set we demonstrate the stable expression and accumulation of the homocitrate synthase, NifV, under aerobic conditions. Arguably, further studies in C. reinhardtii aimed at testing expression and function of the full gene set would provide the groundwork for a concerted future effort to create nitrogen-fixing crops. 相似文献