265 research outputs found
STANDARD METHODS USED IN SOFTWARE DEVELOPMENT IN THE REPUBLIC OF CROATIA
Razvoj softvera složen je posao koji se sastoji od velikog broja koraka, počevši od početnog zahtjeva korisnika, preko analize i izgradnje, pa do implementacije i korištenja. Razvoj softvera podrazumijeva korištenje većeg broja različitih tehnologija i tehnika. Postoje zakonitosti, pravila i redoslijed u korištenju tehnologija i tehnika, pa nije
moguće razviti dobar, koristan i pouzdan softver, ako se njegovom razvoju pristupa ad-hoc. Da bi se osigurala pouzdanost i kvaliteta softvera potrebno je koristiti metodike u njegovom razvoju. Metodike propisuju vrijeme i mjesto korištenja metoda. Radom će se pokazati neke metodike razvoja softvera. Da bi se osigurala brzina, učinkovitost i točnost razvoja softvera, te jednostavnost održavanja, potrebno je u razvoju softvera koristiti CASE tehnologije. Radom će se analizirati značajke CASE tehnologija. CASE tehnologije omogućuju standardizaciju
u razvoju softvera i primjenu normi. Dat će se osvrt na neke standarde i norme koji se primjenjuju u razvoju softvera. U radu će se analizirati podaci Hrvatske gospodarske komore o broju tvrtki i broju zaposlenih u
Republici Hrvatskoj za djelatnost računalno programiranje. Iz istog izvora koristit će se podaci o adresama elektroničke pošte radi provedbe anketnog upitnika o upotrebi metoda i standarda u razvoju softvera. Cilj istraživanja je pokazati kvantitetu i kvalitetu (opisnost, pokrivenost faza razvoja softvera) najčešće korištenih tehnika, metoda i standarda.Software development is a complex process which consists of many steps, starting from the initial user requirements, through analysis and development to the implementation and distribution. Software development involves the use of a number of different technologies and techniques. There are laws, rules and order in the use of technology and techniques, so if software development approach is ad-hoc it is not possible to develop good, useful and reliable software. It is necessary to use methodology in software development in order to ensure the
reliability and quality of software. Methodologies determine the time and place of the use of methods. This article will show some of those methods used for software development. The use of CASE technologies is necessary to ensure speed, accuracy, efficiency of software development and the ease of maintenance. This article will analyze
features of some CASE technologies. CASE technologies also provide standardization in software development and the application of standards. The article will give a review of some of the standards and norms that apply to software development. This article will analyze the data using the Croatian Chamber of Economy Internet site as a source for the number of companies and the number of employees in the Republic of Croatia engaged in computer programming. The same source will be used to get e-mail addresses for a questionnaire on the
use of methods and standards in software development. The goal of the research is to show the quantity and the quality (descriptions, coverage of stages in software development) of the most frequently used techniques, methods and standards
Testing distance characteristics and reference values for ice-hockey straight sprint speed and acceleration. A systematic review and meta-analyses.
Ice-hockey requires high acceleration and speed sprint abilities, but it is unclear what the distance characteristic is for measuring these capabilities. Therefore, this systematic meta-analysis aims to summarize the sprint reference values for different sprint distances and suggest the appropriate use of ice-hockey straight sprint testing protocols. A total of 60 studies with a pooled sample of 2254 males and 398 females aged 11-37 years were included. However, the pooled data for women was not large enough to permit statistical analysis. The sprint distance used for measuring the reported acceleration and speed was between 4-48 m. Increased test distance was positively associated with increased speed (r = 0.70) and negatively with average acceleration (r = -0.87). Forward skating sprint speed increases with the measured distance up to 26 m and do not differ much from longer distance tests, while acceleration decreases with a drop below 3 m/s at distances 15 m and longer. The highest acceleration (5.89 m/s peak, 3.31 m/s average) was achieved in the shortest distances up to 7 m which significantly differs from 8-14 m tests. The highest speed (8.1 m/s peak, 6.76 m/s average) has been recorded between 26-39 m; therefore, distances over 39 m are not necessary to achieve maximum speed. Considering match demands and most reported test distances, 6.1 m is the recommended distance for peak acceleration and 30 m for peak speed. The sprint time, acceleration, and speed of each individual and the number of skating strides should be reported in future studies
ALMA and HST Kiloparsec-scale Imaging of a Quasar-galaxy Merger at Z ≈ 6.2
We present kiloparsec-scale Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope imaging of the quasar PJ308–21 at z = 6.2342, tracing dust, gas (via the [C II] 158 μm line), and young stars. At a resolution of ~0.”3 (≈1.7 kpc), the system is resolved over >4'' (>20 kpc). In particular, it features a main component, identified to be the quasar host galaxy, centered on the accreting supermassive black hole; and two other extended components are on the west and east side: one redshifted and the other blueshifted relative to the quasar. The [C II] emission of the entire system stretches over >1500 km s^(−1) along the line of sight. All the components of the system are observed in dust, [C II], and rest-frame ultraviolet (UV) emission. The inferred [C II] luminosities [(0.9–4.6)×10^9 L⊙]; dust luminosities [(0.15–2.6)×10^(12) L⊙]; rest-frame UV luminosities [(6.6–15)×10^(10) L⊙], their ratios, and the implied gas/dust masses; and star formation rates [11–290 M⊙ yr^(−1)] are typical of high-redshift star-forming galaxies. A toy model of a single satellite galaxy that is tidally stripped by the interaction with the quasar host galaxy can account for the observed velocity and spatial extent of the two extended components. An outflow interpretation of the unique features in PJ308–21 is not supported by the data. PJ308–21 is thus one of the earliest galaxy mergers imaged at cosmic dawn
An ALMA survey of submillimetre galaxies in the COSMOS field: The extent of the radio-emitting region revealed by 3 GHz imaging with the Very Large Array
We determine the radio size distribution of a large sample of 152 SMGs in
COSMOS that were detected with ALMA at 1.3 mm. For this purpose, we used the
observations taken by the VLA-COSMOS 3 GHz Large Project. One hundred and
fifteen of the 152 target SMGs were found to have a 3 GHz counterpart. The
median value of the major axis FWHM at 3 GHz is derived to be kpc.
The radio sizes show no evolutionary trend with redshift, or difference between
different galaxy morphologies. We also derived the spectral indices between 1.4
and 3 GHz, and 3 GHz brightness temperatures for the sources, and the median
values were found to be and K. Three of the
target SMGs, which are also detected with the VLBA, show clearly higher
brightness temperatures than the typical values. Although the observed radio
emission appears to be predominantly powered by star formation and supernova
activity, our results provide a strong indication of the presence of an AGN in
the VLBA and X-ray-detected SMG AzTEC/C61. The median radio-emitting size we
have derived is 1.5-3 times larger than the typical FIR dust-emitting sizes of
SMGs, but similar to that of the SMGs' molecular gas component traced through
mid- line emission of CO. The physical conditions of SMGs probably render
the diffusion of cosmic-ray electrons inefficient, and hence an unlikely
process to lead to the observed extended radio sizes. Instead, our results
point towards a scenario where SMGs are driven by galaxy interactions and
mergers. Besides triggering vigorous starbursts, galaxy collisions can also
pull out the magnetised fluids from the interacting disks, and give rise to a
taffy-like synchrotron-emitting bridge. This provides an explanation for the
spatially extended radio emission of SMGs, and can also cause a deviation from
the well-known IR-radio correlation.Comment: 32 pages (incl. 5 appendices), 17 figures, 7 tables; accepted for
publication in A&A; abstract abridged for arXi
No Evidence for Enhanced [O iii] 88 μm Emission in a z ∼ 6 Quasar Compared to Its Companion Starbursting Galaxy
We present Atacama Large Millimeter/submillimeter Array band 8 observations of the [O III] 88 mu m line and the underlying thermal infrared continuum emission in the z = 6.08 quasar CFHQS J2100-1715 and its dust-obscured starburst companion galaxy (projected distance: similar to 60 kpc). Each galaxy hosts dust-obscured star formation at rates >100 M-circle dot yr(-1), but only the quasar shows evidence for an accreting 10(9) M-circle dot black hole. Therefore we can compare the properties of the interstellar medium in distinct galactic environments in two physically associated objects, similar to 1 Gyr after the big bang. Bright [O III] 88 mu m emission from ionized gas is detected in both systems; the positions and linewidths are consistent with earlier [C II] measurements, indicating that both lines trace the same gravitational potential on galactic scales. The [O III] 88 mu m/far-infrared (FIR) luminosity ratios in both sources fall in the upper range observed in local luminous infrared galaxies of similar dust temperature, although the ratio of the quasar is smaller than in the companion. This suggests that gas ionization by the quasar (expected to lead to strong optical [0 III] 5008 angstrom emission) does not dominantly determine the quasar's FIR [O III] 88 mu m luminosity. Both the inferred number of photons needed for the creation of O++ and the typical line ratios can be accounted for without invoking extreme (top-heavy) stellar initial mass functions in the starbursts of both sources.ERC [740246]; National Science Foundation [AST-1614213]; National Science Foundation of China [11721303]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
The evolution of the cosmic molecular gas density
One of the last missing pieces in the puzzle of galaxy formation and
evolution through cosmic history is a detailed picture of the role of the cold
gas supply in the star-formation process. Cold gas is the fuel for star
formation, and thus regulates the buildup of stellar mass, both through the
amount of material present through a galaxy's gas mass fraction, and through
the efficiency at which it is converted to stars. Over the last decade,
important progress has been made in understanding the relative importance of
these two factors along with the role of feedback, and the first measurements
of the volume density of cold gas out to redshift 4, (the "cold gas history of
the Universe") has been obtained. To match the precision of measurements of the
star formation and black-hole accretion histories over the coming decades, a
two orders of magnitude improvement in molecular line survey speeds is required
compared to what is possible with current facilities. Possible pathways towards
such large gains include significant upgrades to current facilities like ALMA
by 2030 (and beyond), and eventually the construction of a new generation of
radio-to-millimeter wavelength facilities, such as the next generation Very
Large Array (ngVLA) concept.Comment: 7 pages, 2 figures, Science White paper submitted to Astro2020
Decadal Surve
The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The Nature of the Faintest Dusty Star-forming Galaxies
We present a characterization of the physical properties of a sample of 35 securely detected, dusty galaxies in the deep ALMA 1.2 mm image obtained as part of the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS) Large Program. This sample is complemented by 26 additional sources identified via an optical/ infrared source positional prior. Using their well-characterized spectral energy distributions, we derive median stellar masses and star formation rates (SFR) of 4.8 10 ´ 10 M☉ and 30 M☉ yr−1 , respectively, and interquartile ranges of (2.4–11.7) × 1010 M☉ and 20–50 M☉ yr−1 . We derive a median spectroscopic redshift of 1.8 with an interquartile range 1.1–2.6, significantly lower than submillimeter galaxies detected in shallower, wide-field surveys. We find that 59% ± 13%, 6% ± 4%, and 34% ± 9% of our sources are within, above, and below±0.4 dex from the SFR–stellar-mass relation or main sequence (MS), respectively. The ASPECS galaxies closely follow the SFR–molecular gas mass relation and other previously established scaling relations, confirming a factor of five increase of the gas-to-stellar-mass ratio from z = 0.5 to 2.5 and a mild evolution of the gas depletion timescales with a typical value of 0.7 Gyr at z = 1–3. ASPECS galaxies located significantly below the MS, a poorly exploited parameter space, have low gas-to-stellar-mass ratios of ∼0.1–0.2 and long depletion timescales >1 Gyr. Galaxies along the MS dominate the cosmic density of molecular gas at all redshifts. Systems above the MS have an increasing contribution to the total gas reservoirs from z < 1 to z = 2.5, while the opposite is found for galaxies below the MS
ALMA and HST Kiloparsec-scale Imaging of a Quasar-galaxy Merger at Z ≈ 6.2
We present kiloparsec-scale Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope imaging of the quasar PJ308–21 at z = 6.2342, tracing dust, gas (via the [C II] 158 μm line), and young stars. At a resolution of ~0.”3 (≈1.7 kpc), the system is resolved over >4'' (>20 kpc). In particular, it features a main component, identified to be the quasar host galaxy, centered on the accreting supermassive black hole; and two other extended components are on the west and east side: one redshifted and the other blueshifted relative to the quasar. The [C II] emission of the entire system stretches over >1500 km s^(−1) along the line of sight. All the components of the system are observed in dust, [C II], and rest-frame ultraviolet (UV) emission. The inferred [C II] luminosities [(0.9–4.6)×10^9 L⊙]; dust luminosities [(0.15–2.6)×10^(12) L⊙]; rest-frame UV luminosities [(6.6–15)×10^(10) L⊙], their ratios, and the implied gas/dust masses; and star formation rates [11–290 M⊙ yr^(−1)] are typical of high-redshift star-forming galaxies. A toy model of a single satellite galaxy that is tidally stripped by the interaction with the quasar host galaxy can account for the observed velocity and spatial extent of the two extended components. An outflow interpretation of the unique features in PJ308–21 is not supported by the data. PJ308–21 is thus one of the earliest galaxy mergers imaged at cosmic dawn
- …