5,157 research outputs found
Study of contamination of liquid oxygen by gaseous nitrogen First quarterly report, 1 Jul. - 30 Sep. 1964
Analytical model development for contamination study of liquid oxygen by gaseous nitroge
Smanjenje studija fizike
This paper draws attention to the diminishing number of students studying physics both at schools and universities despite its enormous importance for a modern technological society. One possible reason is that many teachers do not convey fully the fascination and excitement of physics and hence fail to inspire young people. A possible way of overcoming this is to place emphasis on "hands-on\u27\u27 experimental work which can be carried out using simple and inexpensive materials which are readily available. Examples of this are given.Upozoravamo na smanjenje broja slušača fizike u školama i na sveučilištima usprkos ogromne važnosti fizike za suvremeno tehnološko društvo. Možda je razlog što nastavnici ne prenose čar i uzbuđenje fizičkih otkrića i propuštaju oduševiti mlade ljude. Moguć način za prevladavanje stanja je da se stavi naglasak na osobni eksperimentalni rad koji se može izvoditi jednostavnim i jeftinim pomagalima, i koja su lako dostupna. Daju se primjeri
Observational Characterization of the Downward Atmospheric Longwave Radiation at the Surface in the City of SĂŁo Paulo
This work describes the seasonal and diurnal variations of downward longwave atmospheric irradiance (LW) at the surface in São Paulo, Brazil, using 5-min-averaged values of LW, air temperature, relative humidity, and solar radiation observed continuously and simultaneously from 1997 to 2006 on a micrometeorological platform, located at the top of a 4-story building. An objective procedure, including 2-step filtering and dome emission effect correction, was used to evaluate the quality of the 9-yr-long LW dataset. The comparison between LW values observed and yielded by the Surface Radiation Budget project shows spatial and temporal agreement, indicating that monthly and annual average values of LW observed in one point of São Paulo can be used as representative of the entire metropolitan region of São Paulo. The maximum monthly averaged value of the LW is observed during summer (389 ± 14 W m-2; January), and the minimum is observed during winter (332 ± 12 W m-2; July). The effective emissivity follows the LW and shows a maximum in summer (0.907 ± 0.032; January) and a minimum in winter (0.818 ± 0.029; June). The mean cloud effect, identified objectively by comparing the monthly averaged values of the LW during clear-sky days and all-sky conditions, intensified the monthly average LW by about 32.0 ± 3.5 W m-2 and the atmospheric effective emissivity by about 0.088 ± 0.024. In August, the driest month of the year in São Paulo, the diurnal evolution of the LW shows a minimum (325 ± 11 W m-2) at 0900 LT and a maximum (345 ± 12 W m-2) at 1800 LT, which lags behind (by 4 h) the maximum diurnal variation of the screen temperature. The diurnal evolution of effective emissivity shows a minimum (0.781 ± 0.027) during daytime and a maximum (0.842 ± 0.030) during nighttime. The diurnal evolution of all-sky condition and clear-sky day differences in the effective emissivity remain relatively constant (7% ± 1%), indicating that clouds do not change the emissivity diurnal pattern. The relationship between effective emissivity and screen air temperature and between effective emissivity and water vapor is complex. During the night, when the planetary boundary layer is shallower, the effective emissivity can be estimated by screen parameters. During the day, the relationship between effective emissivity and screen parameters varies from place to place and depends on the planetary boundary layer process. Because the empirical expressions do not contain enough information about the diurnal variation of the vertical stratification of air temperature and moisture in São Paulo, they are likely to fail in reproducing the diurnal variation of the surface emissivity. The most accurate way to estimate the LW for clear-sky conditions in São Paulo is to use an expression derived from a purely empirical approach
Joint source-channel coding for a quantum multiple access channel
Suppose that two senders each obtain one share of the output of a classical,
bivariate, correlated information source. They would like to transmit the
correlated source to a receiver using a quantum multiple access channel. In
prior work, Cover, El Gamal, and Salehi provided a combined source-channel
coding strategy for a classical multiple access channel which outperforms the
simpler "separation" strategy where separate codebooks are used for the source
coding and the channel coding tasks. In the present paper, we prove that a
coding strategy similar to the Cover-El Gamal-Salehi strategy and a
corresponding quantum simultaneous decoder allow for the reliable transmission
of a source over a quantum multiple access channel, as long as a set of
information inequalities involving the Holevo quantity hold.Comment: 21 pages, v2: minor changes, accepted into Journal of Physics
Improving the quality management systems for energy-efficient social housing projects
Developing and implementing quality management systems (QMS) in construction is particularly difficult because of a lack of standardization, the use of transient workforce and the many parties involved. This paper discusses the challenges faced by social housing providers in the UK when implementing quality assurance programs in their effort to provide their tenants with energy-efficient dwellings. In particular, it focuses on the quality plans defined at the early stages of a project, their impact during the construction process and on the resulting building energy performance. Based on data collected from the project team and documentation, a comparative analysis of the QMS development process of two social housing developments is presented. The key findings show that the two case studies followed different quality management approaches to deliver energy efficient dwellings. The most significant discrepancies were found in defining the energy performance targets and detailing the quality assurance procedures. The contribution of this paper is to create awareness of the importance of defining Quality Assurance Systems with a focus on energy performance from the early stages of a project
Virtual Data in CMS Analysis
The use of virtual data for enhancing the collaboration between large groups
of scientists is explored in several ways:
- by defining ``virtual'' parameter spaces which can be searched and shared
in an organized way by a collaboration of scientists in the course of their
analysis;
- by providing a mechanism to log the provenance of results and the ability
to trace them back to the various stages in the analysis of real or simulated
data;
- by creating ``check points'' in the course of an analysis to permit
collaborators to explore their own analysis branches by refining selections,
improving the signal to background ratio, varying the estimation of parameters,
etc.;
- by facilitating the audit of an analysis and the reproduction of its
results by a different group, or in a peer review context.
We describe a prototype for the analysis of data from the CMS experiment
based on the virtual data system Chimera and the object-oriented data analysis
framework ROOT. The Chimera system is used to chain together several steps in
the analysis process including the Monte Carlo generation of data, the
simulation of detector response, the reconstruction of physics objects and
their subsequent analysis, histogramming and visualization using the ROOT
framework.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 9 pages, LaTeX, 7 eps figures. PSN
TUAT010. V2 - references adde
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Mental health and mediumship: an interpretative phenomenological analysis
There is a lack of research examining the lived experience of mental health as a practicing medium, yet the nature of mediumship work inherently presents a number of challenges to the mental health of practitioners. In this study, we aimed to gain an understanding of how mediums experience their mental health in relation to their mediumistic practice and how they recognise and respond to psychological difficulties experienced by their clients. Fourteen mediums from the North West of England took part in one-to-one interviews, which were transcribed and subject to interpretative phenomenological analysis. Four themes were identified: From past traumas to mediumistic identity; Spirit makes sense, mental illness is chaos; Being resilient but vulnerable; and Ethical mediumistic practice. The research highlights the value of not dismissing or attempting to change appraisals of valued aspects of mediums’ anomalous experiences. However, the findings do indicate that support for exposure to clients’ difficulties (such as vicarious trauma) might be helpful, in the same way in which other professionals might receive support with such experiences. Future research into mediums’ help-seeking for mental health difficulties and their experiences of counselling or psychotherapy would be valuable in identifying if and how their psychological needs are met
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