298 research outputs found

    Utjecaj materijala i geometrije radnog komada kod savijanja laserom

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    Seit den siebziger Jahre ist durch die Einführung des Laserstrahls in die Fertigungstechnik eine ganze Reihe neuer Verfahren entstanden. Einige dieser Verfahren sind mittlerweile in die technische Anwendung übergangen wie zu Beispiel Schneiden, Schweißen, Drehen, Fräsen, Bohren und Umformen. Gemeinsames Merkmal der Lasergestützten Formgebungsverfahren ist die digitale Speicherung der Werkstückgeometrie in einem NC-Programm anstelle der analogen Speicherung im Werkzeug und sukzessive Abarbeitung dieses Programm, die zusätzlich Steuermöglichkeiten während des Prozessablaufs ermöglicht. Weiterhin ergibt die Vorgehensweise eine sehr hohe Flexibilität hinsichtlich der Werkstückgeometrie, die im Bereich des Rapid Prototyping genutzt werden. In dieser Arbeit wird Werkstoff - Geometriewerkstückbeeinflussung auf den Laserstrahlbiegen analysiert. Einfluss hat Blechdicke, längen der Biegekante und Biegeschenkel.Od kada je sedamdesetih godina uveden laser u tehnologiju izrade nastali su mnogi novi postupci. Neki od tih postupaka našli su tehničku primjenu u tehnologiji izrade kao na primjer rezanje, zavarivanje, tokarenje, glodanje, bušenje i oblikovanje metala deformiranjem. Karakteristika je postupka izrade potpomognuta laserom digitalno spremanje geometrije radnog dijela u NC - program, provođenje analognog spremanja podataka u (stroj) alat i sukcesivna obrada ovog programa, koji osigurava dodatno mogućnost upravljanja za vrijeme odvijanja procesa. Nadalje, postiže se fleksibilnost s obzirom na geometriju radnog komada, koja se primjenjuje u području brze izrade prototipova. U ovom se radu analizira utjecaj materijala i geometrije radnog komada na savijanja laserom. Utjecaj ima: debljina lima, duljina ruba savijanja i duljina kraka savijanja

    The Mid-Infrared Properties of X-ray Sources

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    We combine the results of the Spitzer IRAC Shallow Survey and the Chandra XBootes Survey of the 8.5 square degrees Bootes field of the NOAO Deep Wide- Field Survey to produce the largest comparison of mid-IR and X-ray sources to date. The comparison is limited to sources with X-ray fluxes >8x10-15 erg cm-2s-1 in the 0.5-7.0 keV range and mid-IR sources with 3.6 um fluxes brighter than 18.4 mag (12.3 uJy). In this most sensitive IRAC band, 85% of the 3086 X-ray sources have mid-IR counterparts at an 80% confidence level based on a Bayesian matching technique. Only 2.5% of the sample have no IRAC counterpart at all based on visual inspection. Even for a smaller but a significantly deeper Chandra survey in the same field, the IRAC Shallow Survey recovers most of the X-ray sources. A majority (65%) of the Chandra sources detected in all four IRAC bands occupy a well-defined region of IRAC [3.6] - [4.5] vs [5.8] - [8.0] color-color space. These X-ray sources are likely infrared luminous, unobscured type I AGN with little mid-infrared flux contributed by the AGN host galaxy. Of the remaining Chandra sources, most are lower luminosity type I and type II AGN whose mid-IR emission is dominated by the host galaxy, while approximately 5% are either Galactic stars or very local galaxies.Comment: Accepted for publication in Ap

    A fulfilled human life: eliciting sense of place and cultural identity in two UK marine environments through the Community Voice Method

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    Human impacts on the marine environment threaten the wellbeing of hundreds of millions of people. Marine environments are a common-pool resource (CPR) and one of their major management challenges is how to incorporate the value of ecosystem services to society in decision-making. Cultural ecosystem services (CES) relate to the often intangible benefits people receive from their interactions with the natural environment and contribute to individual and collective human wellbeing. Priority knowledge gaps include the need to better understand shared values regarding CES, and how to effectively integrate these values into decision-making. We filmed 40 Community Voice Method interviews with marine stakeholders in two areas of the UK to improve on the valuation of coastal and marine CES. Results show that cultural benefits including sense of place, aesthetic pleasure and cultural identity were bi-directional, contributed directly to a ‘fulfilled human life’ and were associated with charismatic marine life and biodiversity. Other-regarding self-transcendence values were salient underscoring a desire for sustainable marine management. We critically reflect on our analytical framework that integrates aspects of the UK National Ecosystem Assessment and IPBES conceptual frameworks. The thematic codebook developed for this study could prove useful for future comparative studies in other marine CES contexts. We propose that values-led management could increase the efficacy of marine planning strategies

    The Chandra XBootes Survey - III: Optical and Near-IR Counterparts

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    The XBootes Survey is a 5-ks Chandra survey of the Bootes Field of the NOAO Deep Wide-Field Survey (NDWFS). This survey is unique in that it is the largest (9.3 deg^2), contiguous region imaged in X-ray with complementary deep optical and near-IR observations. We present a catalog of the optical counterparts to the 3,213 X-ray point sources detected in the XBootes survey. Using a Bayesian identification scheme, we successfully identified optical counterparts for 98% of the X-ray point sources. The optical colors suggest that the optically detected galaxies are a combination of z<1 massive early-type galaxies and bluer star-forming galaxies whose optical AGN emission is faint or obscured, whereas the majority of the optically detected point sources are likely quasars over a large redshift range. Our large area, X-ray bright, optically deep survey enables us to select a large sub-sample of sources (773) with high X-ray to optical flux ratios (f_x/f_o>10). These objects are likely high redshift and/or dust obscured AGN. These sources have generally harder X-ray spectra than sources with 0.1<f_x/f_o<10. Of the 73 X-ray sources with no optical counterpart in the NDWFS catalog, 47 are truly optically blank down to R~25.5 (the average 50% completeness limit of the NDWFS R-band catalogs). These sources are also likely to be high redshift and/or dust obscured AGN.Comment: 19 pages, 13 figures, ApJ accepted. Catalog can be found at: http://www.noao.edu/noao/noaodeep or ftp://archive.noao.edu/pub/catalogs/xbootes

    The Origin of the 24-micron Excess in Red Galaxies

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    Observations with the Spitzer Space Telescope have revealed a population of red-sequence galaxies with a significant excess in their 24-micron emission compared to what is expected from an old stellar population. We identify 900 red galaxies with 0.15<z<0.3 from the AGN and Galaxy Evolution Survey (AGES) selected from the NOAO Deep Wide-Field Survey Bootes field. Using Spitzer/MIPS, we classify 89 (~10%) with 24-micron infrared excess (f24>0.3 mJy). We determine the prevalence of AGN and star-formation activity in all the AGES galaxies using optical line diagnostics and mid-IR color-color criteria. Using the IRAC color-color diagram from the IRAC Shallow Survey, we find that 64% of the 24-micron excess red galaxies are likely to have strong PAH emission features in the 8-micron IRAC band. This fraction is significantly larger than the 5% of red galaxies with f24<0.3 mJy that are estimated to have strong PAH emission, suggesting that the infrared emission is largely due to star-formation processes. Only 15% of the 24-micron excess red galaxies have optical line diagnostics characteristic of star-formation (64% are classified as AGN and 21% are unclassifiable). The difference between the optical and infrared results suggest that both AGN and star-formation activity is occurring simultaneously in many of the 24-micron excess red galaxies. These results should serve as a warning to studies that exclusively use optical line diagnostics to determine the dominant emission mechanism in the infrared and other bands. We find that ~40% of the 24-micron excess red galaxies are edge-on spiral galaxies with high optical extinctions. The remaining sources are likely to be red galaxies whose 24-micron emission comes from a combination of obscured AGN and star-formation activity.Comment: ApJ, accepted; 11 pages, 7 figures; corrected reference to IRAC Shallow Survey in abstrac

    The Mid-IR and X-ray Selected QSO Luminosity Function

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    We present the J-band luminosity function of 1838 mid-infrared and X-ray selected AGNs in the redshift range 0<z<5.85. These luminosity functions are constructed by combining the deep multi-wavelength broad-band observations from the UV to the mid-IR of the NDWFS Bootes field with the X-ray observations of the XBootes survey and the spectroscopic observations of the same field by AGES. Our sample is primarily composed of IRAC-selected AGNs, targeted using modifications of the Stern et al.(2005) criteria, complemented by MIPS 24 microns and X-ray selected AGNs to alleviate the biases of IRAC mid-IR selection against z~4.5 quasars and AGNs faint with respect to their hosts. This sample provides an accurate link between low and high redshift AGN luminosity functions and does not suffer from the usual incompleteness of optical samples at z~3. We find that the space density of the brightest quasars strongly decreases from z=3 to z=0, while the space density of faint quasars is at least flat, and possibly increasing, over the same redshift range. At z>3 we observe a decrease in the space density of quasars of all brightnesses. We model the luminosity function by a double power-law and find that its evolution cannot be described by either pure luminosity or pure density evolution, but must be a combination of both. Our best-fit model has bright and faint power-law indices consistent with the low redshift measurements based on the 2QZ and 2SLAQ surveys and it generally agrees with the number of bright quasars predicted by other LFs at all redshifts. If we construct the QSO luminosity function using only the IRAC-selected AGNs, we find that the biases inherent to this selection method significantly modify the behavior of phi*(z) only for z<1 and have no significant impact upon the characteristic magnitude M*_J(z).Comment: Corrected minor typo in equations (4) and (6). Accepted for publication in The Astrophysical Journal. 56 pages + 6 tables + 16 figure

    Response Ranking with Deep Matching Networks and External Knowledge in Information-seeking Conversation Systems

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    Intelligent personal assistant systems with either text-based or voice-based conversational interfaces are becoming increasingly popular around the world. Retrieval-based conversation models have the advantages of returning fluent and informative responses. Most existing studies in this area are on open domain "chit-chat" conversations or task / transaction oriented conversations. More research is needed for information-seeking conversations. There is also a lack of modeling external knowledge beyond the dialog utterances among current conversational models. In this paper, we propose a learning framework on the top of deep neural matching networks that leverages external knowledge for response ranking in information-seeking conversation systems. We incorporate external knowledge into deep neural models with pseudo-relevance feedback and QA correspondence knowledge distillation. Extensive experiments with three information-seeking conversation data sets including both open benchmarks and commercial data show that, our methods outperform various baseline methods including several deep text matching models and the state-of-the-art method on response selection in multi-turn conversations. We also perform analysis over different response types, model variations and ranking examples. Our models and research findings provide new insights on how to utilize external knowledge with deep neural models for response selection and have implications for the design of the next generation of information-seeking conversation systems.Comment: Accepted by the 41th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2018), Ann Arbor, Michigan, U.S.A. July 8-12, 2018 (Full Oral Paper
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