4,887 research outputs found
On the necessary conditions for transmitting correlated sources over a multiple access channel
No full textWe study the lossy communication of correlated
sources over a multiple access channel (MAC). In particular, we
provide a new set of necessary conditions for the achievability of
a distortion pair over a given channel. The necessary conditions
are then specialized to the case of bivariate Gaussian sources and
doubly symmetric binary sources over a Gaussian multiple access
channel. Our results indicate that the new necessary conditions
provide the tightest conditions to date in certain cases
On b-I-Open Sets and b-I-Continuous Functions
No full textWe studied some more properties of b-I-open sets and obtained several characterizations of b-I-continuous functions which are introduced by Caksu Guler and Aslim (2005). We also investigated their relationship with other types of functions
Lossy coding of correlated sources over a multiple access channel: necessary conditions and separation results
No full textLossy coding of correlated sources over a multiple access channel (MAC) is studied. First, a joint source-channel coding scheme is presented when the decoder has correlated side information. Next, the optimality of separate source and channel coding, that emerges from the availability of a common observation at the encoders, or side information at the encoders and the decoder, is investigated. It is shown that separation is optimal when the encoders have access to a common observation whose lossless recovery is required at the decoder, and the two sources are independent conditioned on this common observation. Optimality of separation is also proved when the encoder and the decoder have access to shared side information conditioned on which the two sources are independent. These separation results obtained in the presence of side information are then utilized to provide a set of necessary conditions for the transmission of correlated sources over a MAC without side information. Finally, by specializing the obtained necessary conditions to the transmission of binary and Gaussian sources over a MAC, it is shown that they can potentially be tighter than the existing results in the literature, providing a novel converse for this fundamental problem
Using Generalizability Theory to Examine Different Concept Map Scoring Methods
No full textConclusions and Recommendations: According to the results of this study, Phi coefficient was higher in the concept map study in which the holistic scoring method was used. In this study, tasks represented a significant variance component for both scoring methods. This may be interpreted to mean that the levels of difficulty for the tasks differed according to the students using both methods. In each of the scoring methods, the variance related to the raters was found to be zero, which may result in the interpretation that raters scored the maps consistently.Findings and Results: In focusing on the size of the variance estimates according to holistic scoring methods, while the student component (objects of measurement) accounts for one of the largest percentages of th
Track degradation analysis in the scope of railway infrastructure maintenance management systems
No full textStanje elemenata željezničke infrastrukture ključni je faktor koji utječe na sigurnost prometa, raspoloživost infrastrukture, ukupne troškove radova na održavanju i remontu, kao i prihode. Mjerenje i analiza stanja elemenata željezničke infrastrukture je jedini ispravan pristup kako bi se na učinkovit način pratilo njihovo ponašanje te planirali radovi na održavanju. U radu se opisuje optimalna struktura sustava za upravljanje održavanjem željezničke infrastrukture (Railway Maintenance Management System - RMMS) s posebnim osvrtom na primjenu modela degradacije kao jednog od ključnih dijelova RMMS-a.The condition of railway infrastructure elements is the key factor influencing the traffic safety, infrastructure availability, total maintenance and renewal costs, and revenues. The measurement and analysis of the condition of railway infrastructure elements is the only correct approach enabling an efficient monitoring of their behaviour and proper planning of maintenance activities. An optimum structure of the railway Maintenance Management System - RMMS is presented in the paper, with a special emphasis on the utilization of deterioration models, as one of the RMMS’s key components
Is there a flight to quality due to inflation uncertainty?
No full textAfter two types of inflation uncertainty are derived within a time-varying parameter model with GARCH specification, the relationship between inflation uncertainty and interest rates for safe assets is investigated. The results support the existence of a ‘‘flight to quality’’ effect.
A necessary condition for generic rigidity of bar-and-joint frameworks in -space
No full textA graph is -sparse if each subset with induces at most edges in . Maxwell showed in
1864 that a necessary condition for a generic bar-and-joint framework with at
least vertices to be rigid in is that should have a
-sparse subgraph with edges. This necessary
condition is also sufficient when but not when . Cheng and
Sitharam strengthened Maxwell's condition by showing that every maximal
-sparse subgraph of should have edges when
. We extend their result to all .Comment: There was an error in the proof of Theorem 3.3(b) in version 1 of
this paper. A weaker statement was proved in version 2 and then used to
derive the main result Theorem 4.1 when . The proof technique was
subsequently refined in collaboration with Hakan Guler to extend this result
to all in Theorem 3.3 of version
Metal-Salt Enhanced Grafting of Vinylpyridine and Vinylimidazole Monomer Combinations in Radiation Grafted Membranes for High-Temperature PEM Fuel Cells
No full textProton exchange membranes were prepared and characterized for utilization in high-temperature proton exchange membrane fuel cells, HT-PEMFCs. 1-vinylimidazole (1-VIm) and 4-vinylpyridine (4VP) monomers were simultaneously grafted onto pre-irradiated ETFE (ethylene-co-tetrafluoroethylene) films which were prepared using γ-rays with a dose of 100 kGy, as a robust substrate to prepare acid-base composite membranes. The grafting reaction was performed at 60 °C for 24 h followed by protonation via phosphoric acid doping in the subsequent step. The effect of adding ferrous salts as promoters in grafting was investigated by characterization of resultant membranes via thermal gravimetric analysis and mechanical tests. The fuel cell tests were conducted under different relative humidities (RHs) and applied temperatures. Membranes prepared with salt addition exhibited superior proton conductivities. Results including up to 80 mS cm-1 conductivity at 110 °C in 60% RH and excellent thermal stability, even at 300 °C, suggest these membranes are promising for HT-PEMFC applications
Secondary transfer effect of contact on solidarity with immigrants: A test of emotion generalization as an alternative mechanism
No full textPresentazione orale al simposio “Host-migrant relations and acceptance of immigrants in novel contexts: An intergroup contact approach
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