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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Absorption cooling in district heating network: Temperature difference examination in hot water circuit

Yuwardi, Yuwardi January 2013 (has links)
Absorption cooling system driven by district heating network is relized as a smart strategy in Sweden. During summer time when the heating demand is low, the excessive hot water can be directly sold to drive absorption chillers instead of decreasing its production. In addition, this is also one answer to satisfy the cooling demand in more environmentally way since currently only around 26% of cooling demand in Sweden is satisfied by district cooling, the rest is fulfilled by individual air conditioning. Realizing this potential, the purpose of this study is to examine the returning hot water temperature in the district heating network with supply temperature of 70°C and also the effect to the absorption chiller’s COP. Through the simulation result, it is found out that the lowest possible returning water temperature is 55 °C at COP 0,69 with heat rejection (re-cooling) temperature water at 22 °C. This implies that the desired returning hot water temperature of 47 °C cannot be achieved. The lower returning hot water temperature is preferable since it gives the district heating network benefit in term of less distribution pump work, and energy recovery for the condensation process at central heating plant.
62

Artificiell intelligensen i cool jazz : En undersökning över kompositionsförmågan inom AI

Bergman, David January 2021 (has links)
This essay focuses on the compositional ability of Artificial Intelligence Visual Artist(AIVA) and how it performs compared to an amateur jazz musician, in this case I amthe musician. Through a survey published on several social media websites, anyonewho saw the link had the option to participate without the need of any previousexperience. The participants listened to two compositions, one composed by me and theother one composed by AIVA. They were given two options: Was this composed by ahuman or an AI? The last part of the survey the participants were asked to elaborate ontheir previous experience and thought process, to see if experience correlated with theresults. Further, they were also given the option to further explain why they thoughtpicked as they did, and lastly if they thought AI could be used as a tool and how.Ultimately, the majority of the participants could not differentiate between an amateurand AIVA and some argued that the both of the compositions were composed by an AI.Some participants thought both compositions felt harmonically stale, whilst some gavethorough explanations as to why why they could not tell the compositions apart. Inconclusion, elements of AIVA could definitely be improved but the majority agrees thatit can be used as a tool in composition.
63

The Detection and Description of Symbiotic Accretion From Cool Evolved Stars

Lucy, Adrian B. January 2021 (has links)
Symbiotic stars are binaries consisting of a cool evolved G-M/S/C I-III star accreting onto a smaller companion---but the accretion disk itself is rarely detected. Accretion signatures like hard X-rays and optical/ultraviolet flickering are usually suppressed or outshone by shell burning on the accreting white dwarf, the luminous giant, and the giant's wind nebula. In Chapters 2 and 3, we present a new way to find symbiotics that is less biased against accreting-only, non-burning symbiotics with directly detectable accretion disks. Our search methodology is based on finding outliers in SkyMapper Southern Sky Survey broad-band and intermediate-band photometry, using a parameter space built from reconstructed u-g u-v snapshot colors and rapid variability between the three exposures of a 20-minute SkyMapper Main Survey filter sequence, from a sample of luminous red objects selected with 2MASS and Gaia. In a pilot survey employing this new search design, we discovered 12 new symbiotics, including four symbiotics with optical accretion disk flickering and at least two with boundary-layer hard X-rays, as well as 10 new symbiotic candidates. We also discovered optical flickering in the known symbiotic V1044 Cen (CD-36 8436). We conclude that at least 20% of the true population of symbiotics exhibits detectable optical flickering from the inner accretion disk, a substantial fraction of which would not meet the usual H-alpha equivalent width detection thresholds typically used to find symbiotics with traditional narrow-band emission line photometry surveys. There is a significant population of optically-flickering symbiotics hidden both within and beyond the known catalogs of symbiotic stars---however, the question of whether the true population of accreting-only symbiotics is larger than the population of burning symbiotics remains unanswered. We also find that our methods probe a completely different region of parameter space than recent work by the Munari et al. (2021) search for accreting-only symbiotics, while being surprisingly in harmony with the Akras et al. (2019) infrared selection criteria. As an intermediate step in our pilot survey, we explored several outlying regions in our SkyMapper parameter space with optical spectroscopy of 234 luminous red objects, which we present in a 248-page spectral atlas. Our results identify a zone of the u-g u-v snapshot color-color diagram in which virtually all objects are symbiotics. When all-sky uvg colors become available through future DRs of SkyMapper and MEPHISTO, between about 51 and 117 symbiotics missed by previous surveys (of which 11 to 17 have been reported in this work) will be discoverable using only this mostly-symbiotic zone of the color-color diagram, with a near-zero contamination rate. Main Survey filter-sequence variability is also a powerful tool for finding hidden, flickering symbiotics both inside and outside of the mostly-symbiotic color-color zone, but variability must still be used in conjunction with color; there must be enough of an accretion disk contribution to the u-band for it to exhibit detectable variability. We show that yellow post-AGB stars with strong Balmer jump absorption (along with the symbiotic Southern Crab) are outliers with large positive u-v, while some S and carbon stars are outliers with large negative u-v. We also show that it is important to correct the results of SkyMapper's catalog pipeline for variability when dealing with samples containing large-amplitude pulsating stars. In Chapters 4 and 5, we present an in-depth study of one of the few optically-flickering symbiotic stars previously known, MWC 560 (V694 Mon). The persistent outflow from MWC 560 is known to manifest as broad absorption lines (BALs), most prominently at the Balmer transitions. In Chapter 4, we report the detection of high-ionization BALs from C IV, Si IV, N V, and He II in International Ultraviolet Explorer spectra obtained on 1990 April 29-30, when an optical outburst temporarily erased the obscuring "iron curtain" of absorption troughs from Fe II and similar ions. The C IV and Si IV BALs reached maximum radial velocities at least 1000 km/s higher than contemporaneous Mg II and He II BALs; the same behaviors occur in the winds of quasars and cataclysmic variables. An iron curtain lifts to unveil high-ionization BALs during the P Cygni phase observed in some novae, suggesting by analogy a temporary switch in MWC 560 from persistent outflow to discrete mass ejection. At least three more symbiotic stars exhibit broad absorption with blue edges faster than 1500 km/s; high-ionization BALs have been reported in AS 304 (V4018 Sgr), while transient Balmer BALs have been reported in Z And and CH Cyg. These BAL-producing fast outflows can have wider opening angles than has been previously supposed. BAL symbiotics are short-timescale laboratories for their giga-scale analogs, broad absorption line quasars (BALQSOs), which display a similarly wide range of ionization states in their winds. In Chapter 5, we investigate how the accretion disc of MWC 560 is affected by its outflow. We performed optical, radio, X-ray, and ultraviolet observations of MWC 560 during its 2016 optical high state. We tracked multi-wavelength changes that signalled an abrupt increase in outflow power at the initiation of a months-long outflow fast state, just as the optical flux peaked: (1) an abrupt doubling of Balmer absorption velocities; (2) the onset of a 20 𝜇Jy/month increase in radio flux; and (3) an order-of-magnitude increase in soft X-ray flux. Juxtaposing to prior X-ray observations and their coeval optical spectra, we infer that both high-velocity and low-velocity optical outflow components must be simultaneously present to yield a large soft X-ray flux, which may originate in shocks where these fast and slow absorbers collide. Our optical and ultraviolet spectra indicate that the broad absorption-line gas was fast, stable, and dense (⪞10⁶.⁵ cm⁻³) throughout the 2016 outflow fast state, steadily feeding a lower-density (⪝10⁵.⁵ cm⁻³) region of radio-emitting gas. Persistent optical and ultraviolet flickering indicate that the accretion disc remained intact. The stability of these properties in 2016 contrasts to their instability during MWC 560's 1990 outburst, even though the disc reached a similar accretion rate. We propose that the self-regulatory effect of a steady fast outflow from the disc in 2016 prevented a catastrophic ejection of the inner disc. This behaviour in a symbiotic binary resembles disc/outflow relationships governing accretion state changes in X-ray binaries.
64

Understanding the relationship among cool temperatures, growth, metabolism, and energy use of Ictalurus spp.

Vaughn, Abby 09 December 2022 (has links) (PDF)
Although U.S. commercial catfish aquaculture ponds are in temperate regions and experience cool to cold temperatures during the winter, few studies have investigated the effects of low temperatures on catfish physiological processes. Therefore, growth, metabolism, swimming performance, and blood variables were compared between channel (Ictalurus punctatus), blue (I. furcatus), and hybrid (I. furcatus x I. punctatus) catfish at 10 and 20°C. Accelerometers were also used to evaluate relationships among acceleration, metabolism, and tail beat frequency (TBF) during swimming performance tests. Channel catfish experienced the greatest growth, yet growth was diminished across all fish types at 10°C. Metabolic processes, swimming performance, and related blood variables were also diminished at 10°C. Relationships among acceleration, metabolism, and TBF were found indicating cold temperatures inhibit maximum production in catfish and provide initial steps for creating holistic bioenergetic models for further application.
65

Screening and selection for resistance to gray leaf spot (Pyricularia oryzae) in early planted annual ryegrass

Adams, Calyn M. 08 August 2023 (has links) (PDF)
Cattlemen in the southeastern United States widely plant annual ryegrass [Lolium perenne L. spp. multiflorum (Lam.) Husnot] (ARG). It is often planted earlier than the recommended window. This exposes juvenile stands to increased pressure from gray leaf spot (Pyricularia oryzae Cavara) (GLS), causing stand loss. This study was designed to screen for resistance to P. oryzae in two ARG genotypes, Vertyl and a heat-tolerant germplasm (HTARG5) with the objective of developing a crossbred population to be improved using restricted, recurrent phenotypic selection. Experiments were conducted from 2021 – 2022. Disease severity (DS) was assessed 3wk after inoculation with P. oryzae. Vertyl had a significantly lower DS in the preliminary screenings compared to the other genotypes. In experiments 3 and 4, mean DS of Vertyl, HTARG5, and Marshall was not significantly different. These results confirm Vertyl has greater resistance to GLS than HTARG5 and can be a candidate for disease resistance breeding.
66

Kasta ut chintzen : En diskurshistorisk analys av IKEAs reklam ochnationell förnyelse i Storbritannien på 1990-talet / Chuck out your chintz : A discourse-historical analysis of IKEAsadvertisement and national renewal in Britainin the 1990s

Steneholt, Nilla January 2023 (has links)
Storbritannien präglades på 1990-talet av politiskt och kulturellt nytänkande med New Labour och kulturfenomenet Cool Britannia samtidigt som IKEA försökte etablera sig i landet. Min diskurshistoriska analys undersöker hur IKEAs reklamkampanjer “Chuck out your chintz” och “Stop being so English” anpassades till framväxande föreställningar om ett nytt Storbritannien. Studien motiveras av att det finns ett forskningsgap när det gäller IKEAs reklamanpassning i nationella marknader och utgår från Douglas B. Holts kulturella varumärkesteori om hur varumärken blir ikoniska genom identitetsmyter som riktar sig till kulturella motsättningar. Resultaten pekar på interdiskursivitet i New Labours och IKEAs kommunikation med ett ideologiskt narrativ om ett modernt och klasslöst samhälle. I “Stop being so English” framträder även en ideologi om sexuell liberalism som kopplas ihop med IKEAs svenska betoning i sin marknadsföring. Analysen indikerar att IKEA konstruerade en identitetsmyt som jämnade ut kulturella motsättningar om social klass och nationell identitet där människor kunde delta i det nya Storbritannien som konsumenter. Då företag som IKEA använder kulturell marknadsföring kan reklam tillämpas i idéhistoriska undersökningar för att belysa samhällsförändringar. Reklam kan vara ett kulturellt uttryck som är bärare av föreställningar och genom att identifiera identitetsmyter i reklamen kan man urskilja de ideologier som verkar i en kultur.
67

Radio Emission from Substellar Companions of Evolved Cool Stars.

Ignace, Richard, Giroux, Mark, Luttermoser, Donald 01 March 2010 (has links) (PDF)
A number of substellar companions to evolved cool stars have now been reported. Cool giants are distinct from their progenitor main-sequence low-mass stars in a number of ways. First, the mass loss rates of cool giant stars are orders of magnitude greater than for the late-type main-sequence stars. Secondly, on the cool side of the Linsky–Haisch ‘dividing line’, K and M giant stars are not X-ray sources, although they do show evidence for chromospheres. As a result, cool star winds are largely neutral for those spectral types, suggesting that planetary or brown dwarf magnetospheres will not be effective in standing off the stellar wind. In this case, one expects the formation of a bow shock morphology at the companion, deep inside its magnetosphere. We explore radio emissions from substellar companions to giant stars using (a) the radiometric Bode's law and (b) a model for a bow shock morphology. Stars that are X-ray emitters likely have fully ionized winds, and the radio emission can be at the milli-Jansky level in favourable conditions. Non-coronal giant stars produce only micro-Jansky level emissions when adjusted for low-level ionizations. If the largely neutral flow penetrates the magnetosphere, a bow shock results that can be strong enough to ionize hydrogen. The incoherent cyclotron emission is sub-micro-Jansky. However, the long wavelength radio emission of Solar system objects is dominated by the cyclotron maser instability (CMI) mechanism. Our study leads to the following two observational prospects. First, for coronal giant stars that have ionized winds, application of the radiometic Bode's law indicates that long wavelength emission from substellar companions to giant stars may be detectable or nearly detectable with existing facilities. Secondly, for the non-coronal giant stars that have neutral winds, the resultant bow shock may act as a ‘feeder’ of electrons that is well embedded in the companion's magnetosphere. Incoherent cyclotron emissions are far too faint to be detectable, even with next generation facilities; however, much brighter flux densities may be achievable when CMI is considered.
68

Preliminary Evaluation of Cool-crete

Ellison, Travis S. 08 July 2016 (has links)
No description available.
69

Mapping the Local Galactic Halo and An Image Motion Compensation System for the Multi-Object Double Spectrograph

Marshall, Jennifer L. 13 September 2006 (has links)
No description available.
70

Using a Leadership and Civic Engagement Course to Address the Retention of African American Males

Cunningham, Patricia Frances Rene 20 October 2011 (has links)
No description available.

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