Search results for "DISTANCE"
showing 10 items of 1009 documents
Parameter properties and stellar population of the old open cluster NGC 3960
2004
We present a $BVI$ photometric and astrometric catalogue of the open cluster NGC 3960, down to limiting magnitude $V\sim22$, obtained from observations taken with the Wide Field Imager camera at the MPG/ESO 2.2 m Telescope at La Silla. The photometry of all the stars detected in our field of view has been used to estimate a map of the strong differential reddening affecting this area. Our results indicate that, within the region where the cluster dominates, the $E(V-I)$ values range from 0.21 up to 0.78, with $E(V-I)=0.36$ ($E(B-V)=0.29$) at the nominal cluster centroid position; color excesses $E(V-I)$ up to 1 mag have been measured in the external regions of the field of view where field …
High Precision Differential Astrometry in Large Angular Separation Pairs of Radiosources
1994
We show preliminary results of three of the four radiosource pairs with angular separations ranging from 0.01° to 6° where we have determined such a separation with a typical fractional precision of 10-8using phase delays corrected for structural and ionospheric contributions. In the radiosource 4C39.25 we measure a motion with respect to an external radiosource which is compatible with previously reported internal superluminal motion.
A Preliminary Analysis of a New Chandra Observation (ObsID 6148) of Cir X-1
2008
We present the preliminary spectral analysis of a 25 ks long Chandra observation of the peculiar source Cir X–1 near the periastron passage. We estimate more precise coordinates of the source compatible with the optical and radio counterpart coordinates. We detect emission lines associated to Mg XII, Si XIII, Si XIV, S XV, S XVI Ar XVII, Ar XVIII, Ca XIX, Ca XX, Fe XXV, Fe XXVI showing a redshift of 470 km s−1. The more intense emission features at 6.6 keV show a double‐peaked shape that can be modelled with two or three Gaussian lines.
A Preliminary BeppoSAX Study of the (Bright) Atoll Source GX 9+1
2003
We report the preliminary results of a 350 ks BeppoSAX observation of the bright atoll source GX 9+1. In the field of view of the MECS instrument we discovered a X-ray pulsar, designated SAX J1802.7 - 2017, at an angular distance from GX 9+1 of ∼ 22 ′ . Since the X-ray emission of SAX J1802.7 - 2017 contaminates the energy spectrum above 10 keV we studied the energy spectrum of GX 9+1 in the energy band 0.1 - 10keV. We selected four regions in the color-color diagram and extracted one spectrum from each region. A bump below 1keV is present in the spectra using a model composed by a Comptonized component absorbed by neutral matter having an equivalent hydrogen column of 1.5 x 10 22 cm -2 . T…
Education in Ethiopia: Strengthening the Foundation for Sustainable Progress
2005
International audience; With the end of civil war in 1991, Ethiopia's government launched a New Education and Training Policy in 1994 which, by the early 2000s, had already produced remarkable results. The gross enrollment ratio rose from 20 to 62 percent in primary education between 1993-94 and 2001-02; and in secondary and higher education it climbed, respectively, from 8 to 12 percent and from 0.5 to 1.7 percent. Yet the government can hardly afford to rest on its laurels. Primary education is still not universal, and already there are concerns about plummeting educational quality and the growing pressures to expand post-primary education. Addressing these challenges will require more re…
DISTANCE LEARNING AND COVID-19 FROM STUDENTS’ PERSPECTIVE: DO THEY HAVE THE SKILLS TO DEAL WITH THE UNPRECEDENTED SITUATION?
2021
As a result of the COVID-19 pandemic, more than 1,6 billion children worldwide were forced to discontinue face-to-face education and continue with distance learning (OECD, 2020). To many students as well as teachers this was their first experience with distance learning. Students' ability to adapt to distance learning varies and depends on different factors, including individual factors such as the ability to cope with new situations, solve problems and manage their own learning process. In order to successfully deal with the new circumstances in education, it is necessary to work at all levels - including the level of policy development, level of schools as organizations, and at the indivi…
Assessing changes in eco-productivity of wastewater treatment plants: The role of costs, pollutant removal efficiency, and greenhouse gas emissions
2018
Abstract Improving eco-efficiency of wastewater treatment plants (WWTPs) has been identified as being essential for achieving urban sustainability. Several previous papers have evaluated the eco-efficiency of WWTPs using data envelopment analysis (DEA) models. However, those models provided only a static assessment in that they ignored possible fluctuations over time within each plant. To overcome this temporal limitation, this paper evaluates dynamic eco-efficiency (changes in eco-productivity over time) of WWTPs using the dynamic weighted Russell directional distance model (WRDDM). This approach allows one to obtain an eco-productivity change index for each major component of the WRDDM mo…
Analysing the efficiency of wastewater treatment plants: The problem of the definition of desirable outputs and its solution
2020
Abstract Evaluating the efficiency of wastewater treatment plants (WWTPs) is highly relevant to improve their performance from an economic and environmental perspective. The issue is even more critical in countries where WWTPs are benchmarked to regulate water companies and define WWTPs’ economic and environmental objectives. Despite the large number of previous studies on this topic, none has considered that the amount of outputs produced by the WWTPs is restricted by the concentration of pollutants in the effluent. To overcome this limitation, the study’s main objective was to propose a new variant of the Weighted Russell Directional Distance Model (WRDDM) that would solve problems regard…
On Inverse Distance Weighting in Pollution Models
2011
When evaluating the impact of pollution, measurements from remote stations are often weighted by the inverse of distance raised to some nonnegative power (IDW). This is derived from Shepard's method of spatial interpolation (1968). The paper discusses the arbitrary character of the exponent of distance and the problem of monitoring stations that are close to the reference point. From elementary laws of physics, it is determined which exponent of distance should be chosen (or its upper bound) depending on the form of pollution encountered, such as radiant pollution (including radioactivity and sound), air pollution (plumes, puffs, and motionless clouds by using the classical Gaussian model),…
Pollution models and inverse distance weighting: some critical remarks
2013
International audience; When evaluating the impact of pollution, measurements from remote stations are often weighted by the inverse of distance raised to some nonnegative power (IDW). This is derived from Shepard's method of spatial interpolation (1968). The paper discusses the arbitrary character of the exponent of distance and the problem of monitoring stations that are close to the reference point. From elementary laws of physics, it is determined which exponent of distance should be chosen (or its upper bound) depending on the form of pollution encountered, such as radiant pollution (including radioactivity and sound), air pollution (plumes, puffs, and motionless clouds by using the cl…