671 research outputs found

    Locally Stationary Graph Processes

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    Stationary graph process models are commonly used in the analysis and inference of data sets collected on irregular network topologies. While most of the existing methods represent graph signals with a single stationary process model that is globally valid on the entire graph, in many practical problems, the characteristics of the process may be subject to local variations in different regions of the graph. In this work, we propose a locally stationary graph process (LSGP) model that aims to extend the classical concept of local stationarity to irregular graph domains. We characterize local stationarity by expressing the overall process as the combination of a set of component processes such that the extent to which the process adheres to each component varies smoothly over the graph. We propose an algorithm for computing LSGP models from realizations of the process, and also study the approximation of LSGPs locally with WSS processes. Experiments on signal interpolation problems show that the proposed process model provides accurate signal representations competitive with the state of the art

    Mining-Assisted Heavy Oil Production (MAHOP)

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    This research aims to investigate and compare the ultimate recovery from the largest oil reserve in Turkey (1.85 billion barrels) using a new method called mining-assisted heavy oil production (MAHOP) with conventional SAGD. Tunnels will be excavated from the surface to the reservoir. Fan-shaped up holes will then be drilled in the reservoir from the tunnels.Heavy oil production through these tunnels will be explored using SAGD method. Several numerical models have been designed using CMG’s STARS simulator. Since the fan wells are opened vertically and at certain intervals along the tunnel, both a tight vertical fracturing of these wells and a separate fracture network formed by micro fractures in the vicinity of the fan holes are formed.The validation of these hypotheses has been conducted in CMG which showed that MAHOP gave better results compared to conventional SAGD where two horizontal wells are used. MAHOP gave better recovery values with less steam oil ratios. With the results of the simulation study a laboratory model was designed. Experimental operational parameters using three different wettability cases were simulated to observe recovery by considering several possible physical effects such as steam distillation and in-situ upgrading. Saturation and pressure distributions were also obtained

    The Investigation of the Effects of Plasma Treatment on the Dyeing Properties of Polyester/Viscose Nonwoven Fabrics

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    AbstractIn this study, Polyester/Viscose (PET/CV) nonwoven fabrics were treated with oxygen plasma application. The plasma application was carried out for 1and 10minutes at low frequency. After then, the samples were dyed with disperse dyes. Where same samples were dyed with carriers, the others were dyed without carriers. Finally, the effects of plasma treatment on dyeing properties of PET/CV nonwoven fabrics were investigated at 3% darkness. The aim of this study is that the effect of hydrophility caused by the plasma application on dyeability properties of samples was investigated

    Comparison between in situ dry matter degradation and in vitro gas production of tannin-containing leaves from four tree species

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    Dry matter (DM) degradation of Glycrrhiza glabra L, Arbutus andrachne, Juniperus communis, and Pistica lentiscus was determined using two different techniques: (i) the in vitro gas production and (ii) the in situ nylon bag degradability technique. Samples were incubated in situ and in vitro for 3, 6, 12, 24, 48, 72 and 96 h. In situ and in vitro DM degradation kinetics were described using the equation y = a + b (1 - e ct). At all incubation times except 3 and 72 h the cumulative gas production of J. communis was significantly lower than that of G. glabra, A. andrachne and P. lentiscus. At 3, 6 and 12 h incubation times the DM disappearance of J. communis was only significantly lower than that of P. lentiscus. At 24 and 48 h incubation times DM disappearance of J. communis was significantly lower than that of A. andrachne and P. lentiscus. There were significant relationships between in vitro gas production and in situ DM disappearance at 24 h and 96 h incubation times. The gas productions at 24 and 96 h incubation explained 51.2 and 52.4% of variation of DM disappearance, respectively. Gas production from the insoluble fraction (b) alone explained 66.4% of the variation of effective DM degradability (EDMD). The inclusion of gas production from quickly soluble fraction (a) and rate constant (c) of gas production in the regression equation did not improve the accuracy of predicting EDMD. It was concluded that in situ DM disappearance parameters of tannin-containing tree leaves such as used in this present study may be predicted from in vitro gas production parameters. South African Journal of Animal Science Vol. 34(4) 2004: 233-24

    A new hybrid risk assessment process for cyber security design of smart grids using fuzzy analytic hierarchy processes

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    IT vulnerabilities, cyber threats, and resulting risks significantly impact the stability of current and future power grids. The results of a Risk Assessment process contribute to a better understanding of the causes and nature of the associated risks. The risks assessed by experts are available in both numerical and linguistic representations – this makes it beneficial to include a combination of linguistic and numerical analyses. In this paper, we propose a new Hybrid Risk Assessment method based on fuzzy logic, leading to more precise results. The presented approach specifies the variables and membership functions of fuzzy logic with reference to Smart Grids. For this propose, a case study with five risk events in a small-scale Smart Grid is carried out as an example. The results can then support decision-makers in ensuring grid stability

    Effects of Sour Yogurt as an Alternative Additive in Second Crop Corn Silage

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    In this study, we evaluated the influence of sour yogurt as a natural microbial inoculant in second-crop corn silages. For this purpose, two trials with different dilution rates were conducted. In Trial I, the groups 10 g sour yogurt + 5 g distilled water (SY10-2), 20 g sour yogurt + 10 g distilled water (SY20-2), 30 g sour yogurt + 15 g distilled water (SY30-2), 40 g sour yogurt + 20 g distilled water (SY40-2), 50 g sour yogurt + 25 g distilled water (SY50-2) and no additives were added to the control (CON) group. The groups in Trial II, 10 g sour yogurt + 10 g distilled water (SY10-1), 20 g sour yogurt + 20 g distilled water (SY20-1), 30 g sour yogurt + 30 g distilled water (SY30-1), 40 g sour yogurt + 40 g distilled water (SY40-1), 50 g sour yogurt + 50 g distilled water (SY50-1) and 10 g of distilled water were added to the control (WCON) group. For the silages opened on the 90th day of ensiling, the highest lactic acid content was determined in the SY20-2 and SY20-1 groups (p < 0.05). The lowest amount of ammonia nitrogen was in the SY30-2 group (p < 0.05). In the aerobic period, the SY10-2 and SY20-2 groups remained more stable than the others. As a result, the SY20-2, SY30-2, SY20-1, and SY30-1 groups improved the fermentation quality of corn silages, but the effect on aerobic stability was not significant and was similarly found with the homofermentative bacterial inoculants
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