48 research outputs found

    APPLICATION OF MULTI-AGENT SYSTEMS IN ELECTRICITY MARKET SIMULATORS

    Get PDF
    Kako procesi liberalizacije i deregulacije tržišta električne energije diljem svijeta uzimaju sve više maha, tako se broj sudionika na tržištu, a ujedno i njihova raznolikost, naglo povećava. U tradicionalnom monopolističkom modelu tržišta svi su procesi, koji se odvijaju u elektroenergetskom sustavu (EES), bili pod nadzorom vertikalno integriranih kompanija. No, kako se tržišna logika mijenja od one usmjerene na što je niže moguće troškove proizvodnje električne energije na težnju k što većem profitu, tako se i rizik raspodjeljuje među svim tržišnim sudionicima podjednako i nije više u potpunosti na leđima krajnjih potrošača. U takvim nesigurnim uvjetima, u kojima se cijena električne energije mijenja iz sata u sat, svaki tržišni sudionik želi se osloniti na pomoć pouzdanog alata koji bi mu pomogao pri donošenju optimalnih i kvalitetnih odluka i strateških nastupa. Gotovo istodobno strelovito napreduje relativno nova znanstvena disciplina – agentsko modeliranje procesa iz stvarnog života. Adaptivnim i inteligentnim agentima, s mogućnošću komunikacije, pokušavaju se predočiti kako pojedinci tako i institucije te njihova djelovanja. Nedvojbeno je da upravo ovakav, agentski pristup može pronaći i već pronalazi svoje mjesto i u simuliranju procesa koji se odvijaju na tržištu električne energije. Što je model kvalitetniji i što je bolje prilagođen stvarnom stanju specifičnog tržišta, to će i rezultati njegovog korisnika biti bolji i njegov profit veći.Since the liberalization and deregulation of the electricity markets throughout the world are in full swing, the number of market participants, as well as their diversity, is sharply increasing. In the traditional monopolistic market model, all the processes that occur in a power system have been supervised by vertically integrated companies. Since market logic is changing from that oriented toward minimizing generation costs for electrical energy to the trend of maximizing profit, the risk is being distributed among all the market participants uniformly and is no longer entirely borne by the final consumers. Under such uncertain conditions, in which the prices of electrical energy change from hour to hour, each market participant wants a reliable tool to facilitate optimal and quality decisions and strategic performance. At practically the same time, a relatively new scientific discipline is making rapid advances agent-based process modeling from real life. Through adaptive and intelligent agents, with the possibility of communication, attempts are being made to depict the activities of individuals and institutions. Just such an agent approach has undoubtedly already found a role in the simulation of processes that occur on the electrical energy market. The better the model and the better its adaptation to the real state of a specific market, the better the results for the user and the greater the profit

    Sub-millimeter galaxies as progenitors of compact quiescent galaxies

    Get PDF
    Three billion years after the big bang (at redshift z=2), half of the most massive galaxies were already old, quiescent systems with little to no residual star formation and extremely compact with stellar mass densities at least an order of magnitude larger than in low redshift ellipticals, their descendants. Little is known about how they formed, but their evolved, dense stellar populations suggest formation within intense, compact starbursts 1-2 Gyr earlier (at 3<z<6). Simulations show that gas-rich major mergers can give rise to such starbursts which produce dense remnants. Sub-millimeter selected galaxies (SMGs) are prime examples of intense, gas-rich, starbursts. With a new, representative spectroscopic sample of compact quiescent galaxies at z=2 and a statistically well-understood sample of SMGs, we show that z=3-6 SMGs are consistent with being the progenitors of z=2 quiescent galaxies, matching their formation redshifts and their distributions of sizes, stellar masses and internal velocities. Assuming an evolutionary connection, their space densities also match if the mean duty cycle of SMG starbursts is 42 (+40/-29) Myr (consistent with independent estimates), which indicates that the bulk of stars in these massive galaxies were formed in a major, early surge of star-formation. These results suggests a coherent picture of the formation history of the most massive galaxies in the universe, from their initial burst of violent star-formation through their appearance as high stellar-density galaxy cores and to their ultimate fate as giant ellipticals.Comment: ApJ (in press

    Age Affects the Expression of Maternal Care and Subsequent Behavioural Development of Offspring in a Precocial Bird

    Get PDF
    Variations of breeding success with age have been studied largely in iteroparous species and particularly in birds: survival of offspring increases with parental age until senescence. Nevertheless, these results are from observations of free-living individuals and therefore, it remains impossible to determine whether these variations result from parental investment or efficiency or both, and whether these variations occur during the prenatal or the postnatal stage or during both. Our study aimed first, to determine whether age had an impact on the expression of maternal breeding care by comparing inexperienced female birds of two different ages, and second, to define how these potential differences impact chicks’ growth and behavioural development. We made 22 2-month-old and 22 8-month-old female Japanese quail foster 1-day-old chicks. We observed their maternal behaviour until the chicks were 11 days old and then tested these chicks after separation from their mothers. Several behavioural tests estimated their fearfulness and their sociality. We observed first that a longer induction was required for young females to express maternal behaviour. Subsequently as many young females as elder females expressed maternal behaviour, but young females warmed chicks less, expressed less covering postures and rejected their chicks more. Chicks brooded by elder females presented higher growth rates and more fearfulness and sociality. Our results reveal that maternal investment increased with age independently of maternal experience, suggesting modification of hormone levels implied in maternal behaviour. Isolated effects of maternal experience should now be assessed in females of the same age. In addition, our results show, for first time in birds, that variations in maternal care directly induce important differences in the behavioural development of chicks. Finally, our results confirm that Japanese quail remains a great laboratory model of avian maternal behaviour and that the way we sample maternal behaviour is highly productive

    The VLA-COSMOS 3 GHz Large Project: continuum data and source catalog release

    Get PDF
    We present the VLA-COSMOS 3 GHz Large Project based on 384 hours of observations with the Karl G. Jansky Very Large Array (VLA) at 3 GHz (10 cm) toward the two square degree Cosmic Evolution Survey (COSMOS) field. The final mosaic reaches a median rms of 2.3 uJy/beam over the two square degrees at an angular resolution of 0.75". To fully account for the spectral shape and resolution variations across the broad (2 GHz) band, we image all data with a multiscale, multifrequency synthesis algorithm. We present a catalog of 10,830 radio sources down to 5 sigma, out of which 67 are combined from multiple components. Comparing the positions of our 3 GHz sources with those from the Very Long Baseline Array (VLBA)-COSMOS survey, we estimate that the astrometry is accurate to 0.01" at the bright end (signal-to-noise ratio, S/N_3GHz > 20). Survival analysis on our data combined with the VLA-COSMOS 1.4~GHz Joint Project catalog yields an expected median radio spectral index of alpha=-0.7. We compute completeness corrections via Monte Carlo simulations to derive the corrected 3 GHz source counts. Our counts are in agreement with previously derived 3 GHz counts based on single-pointing (0.087 square degrees) VLA data. In summary, the VLA-COSMOS 3 GHz Large Project simultaneously provides the largest and deepest radio continuum survey at high (0.75") angular resolution to date, bridging the gap between last-generation and next-generation surveys

    Biophilic architecture: a review of the rationale and outcomes

    Get PDF
    Contemporary cities have high stress levels, mental health issues, high crime levels and ill health, while the built environment shows increasing problems with urban heat island effects and air and water pollution. Emerging from these concerns is a new set of design principles and practices where nature needs to play a bigger part called “biophilic architecture”. This design approach asserts that humans have an innate connection with nature that can assist to make buildings and cities more effective human abodes. This paper examines the evidence for this innate human psychological and physiological link to nature and then assesses the emerging research supporting the multiple social, environmental and economic benefits of biophilic architecture

    The lycopene content in pulp ad peel of five fresh tomato varieties

    No full text
    The lycopene content in pulp and peel of five fresh tomato cultivars, most common on Croatian market, was determined by spectrophotometry and the high-performance liquid chromatography (HPLC). Peels from the raw tomatoes contained more lycopene (expressed on a fresh basis) than the pulps: the ratio was 3.75±1.08 for spectrophotometric and 3.50±0.95 for HPLC measurements. Comparison of the results of lycopene content expressed on a dry weight basis revealed that the peel from raw tomato contains 1.74±0.36 times (spectrophotometry) more lycopene than the pulp as compared to a factor of 1.61±0.24 obtained by HPLC analysis. Fraction of the pulp in a whole tomato was found to vary between 89.9 and 95.2%, while that of tomato peel was between 4.9 and 10.1%. Nutritional habits in Croatia often include tomato-based food, all year around, prepared partlyof whole fresh tomatoes (including peel), partly of industrial tomato products (from which peel is often excluded). This study provides evidence that the peel of one of the most common varieties of tomatoes on Croatian market is richer in lycopene than the pulp and, moreover, that a diet including 100 g of raw tomatoes provides 1.35±0.29 mg lycopene from pulp as compared to 0.35±0.18 mg lycopene from tomato peel. In addition, results of this study will be useful in further attempts to quantify lycopene content of intact, whole tomatoes by means of the nondestructive, photoacoustic metho

    The lycopene content in pulp and peel of five fresh tomato cultivars

    No full text
    The lycopene content in pulp and peel of five fresh tomato cultivars, most common on Croatian market, was determined by spectrophotometry and the high-performance liquid chromatography (HPLC). Peels from the raw tomatoes contained more lycopene (expressed on a fresh basis) than the pulps: the ratio was 3.75±1.08 for spectrophotometric and 3.50±0.95 for HPLC measurements. Comparison of the results of lycopene content expressed on a dry weight basis revealed that the peel from raw tomato contains 1.74±0.36 times (spectrophotometry) more lycopene than the pulp as compared to a factor of 1.61±0.24 obtained by HPLC analysis. Fraction of the pulp in a whole tomato was found to vary between 89.9 and 95.2%, while that of tomato peel was between 4.9 and 10.1%. Nutritional habits in Croatia often include tomato-based food, all year around, prepared partlyof whole fresh tomatoes (including peel), partly of industrial tomato products (from which peel is often excluded). This study provides evidence that the peel of one of the most common varieties of tomatoes on Croatian market is richer in lycopene than the pulp and, moreover, that a diet including 100 g of raw tomatoes provides 1.35±0.29 mg lycopene from pulp as compared to 0.35±0.18 mg lycopene from tomato peel. In addition, results of this study will be useful in further attempts to quantify lycopene content of intact, whole tomatoes by means of the nondestructive, photoacoustic method

    Interacting with nature improves cognition and affect for individuals with depression

    No full text
    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150698/1/2012_Berman_et_al_Interacting_with_natures_improves_cognition.pd
    corecore