Single stage and double absorption heat transformers used to recover energy in a distillation column of butane and pentane

This paper presents the theoretical analysis of the use of single stage and double absorption heat transformers operating with the water–lithium bromide mixture coupled to a butane and pentane distillation column in a Mexican refinery. A mathematical model of the heat transformers was developed in FORTRAN and integrated as a user model to the Aspen Plus simulation code. Both components coupled to the column were modelled on steady-state conditions. The results show that it is theoretically possible to reduce the energy consumed in the reboiler between 26 and 43% by the use of single stage heat transformer at specific conditions, and between 28 and 33% with double absorption heat transformers for a wide range of operating conditions. Copyright © 2003 John Wiley & Sons, Ltd.     

Effects of aluminum on the oxidation of 25Cr-35Ni cast steels

The oxidation kinetics and morphological development during reaction of two cast austenitic steels at 1000°C in pure dry oxygen at 20 kPa are reported. Both steels contained approximately 25 wt.% Cr and 35 wt.% Ni and, in addition, one steel contained 3.3 wt. %. Both steels oxidized to form external scales consisting mainly of Cr₂O₃ with a thin outer layer of manganese rich spinel. Scale growth kinetics were parabolic, and somewhat faster rates were observed for the aluminum bearing steel. In both steels, deep internal oxidation occurred at the site of primary (interdendritic) carbides. The kinetics of this process were parabolic, and rate control was attributed to oxygen diffusion along the interface between internal oxide and matrix metal. In the aluminum-free steel, interdendritic carbides were converted to chromium rich oxide, but when aluminum was present, a sheath of aluminum rich oxide formed around the carbides. In this latter case, the rate of interdendritic penetration was somewhat slower. The aluminum bearing steel also formed large numbers of rod-shaped Al₂O₃ precipitates within the austenitic dendrites. Deepening of the Al₂O₃ precipitate zone also proceeded according to parabolic kinetics at a rate consistent with rate control by diffusion of oxygen along the oxide-alloy interfaces.     

Atmospheric correction of optical imagery from MODIS and Reanalysis atmospheric products

In this paper we analyze the differences obtained in the atmospheric correction of optical imagery covering bands located in the Visible and Near Infra-Red (VNIR), Short-Wave Infra-Red (SWIR) and Themal-Infrared (TIR) spectral regions when atmospheric profiles extracted from different sources are used. In particular, three sensors were used, Compact High Resolution Imaging Spectrometer (CHRIS), Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) and Landsat5 Thematic Mapper (TM), whereas four atmospheric profiles sources were considered: i) local soundings launched near the sensor overpass time, ii) Moderate Resolution Radiometer (MODIS) atmospheric profiles product (MOD07), iii) Atmospheric Correction Parameter Calculator (ACPC) generated by the National Center for Environmental Prediction (NCEP) and iv) Modified Atmospheric Profiles from Reanalysis Information (MAPRI), which includes data from NCEP and National Center of Atmospheric Research (NCAR) Reanalysis project but interpolated to 34 atmospheric levels and resampled to 0.5° × 0.5°. MODIS aerosol product (MOD04) was also used to extract Aerosol Optical Thickness (AOT) values at 550 nm. Analysis was performed for three test dates (12th July 2003, 18th July 2004 and 13th July 2005) over an agricultural area in Spain. Results showed that air temperature vertical profiles were similar for the four sources, whereas dew point temperature profiles showed significant differences at some particular levels. Atmospheric profiles were used as input to MODTRAN4 radiative transfer code in order to compute atmospheric parameters involved in atmospheric correction, with the aim of retrieving surface reflectances in the case of VNIR and SWIR regions, and Land Surface Temperature (LST) in the case of the TIR region. For the VNIR and SWIR region, significant differences depending on the atmospheric profile used were not found, particularly in the Visible region in which the AOT content is the main parameter involved in the atmospheric correction. In the case of TIR, differences depending on the atmospheric profile used were appreciable, since in this case the main parameter involved in the atmospheric correction is the water vapor content, which depends on the vertical profile. In terms of LST retrieval from ASTER data (2004 test case), all profiles provided satisfactory results compared to the ones obtained when using a local sounding, with errors of 0.3 K for ACPC and MAPRI cases and 0.7 K for MOD07. When retrieving LST from TM data (2005 test case), errors for MOD07 and MAPRI were 0.6 and 0.9 K respectively, whereas ACPC provided an error of 2 K. The results presented in this paper show that the different atmospheric profile sources are useful for accurate atmospheric correction when local soundings are not available. In particular, MOD07 product provides atmospheric information at the highest spatial resolution, 5 km, although its use is limited from 2000 to present, whereas MAPRI provides historical information from 1970 to present, but at lower spatial resolution.     

Convolutional Sparse Coding for High Dynamic Range Imaging

Current HDR acquisition techniques are based on either (i) fusing multibracketed, low dynamic range (LDR) images, (ii) modifying existing hardware and capturing different exposures simultaneously with multiple sensors, or (iii) reconstructing a single image with spatially‐varying pixel exposures. In this paper, we propose a novel algorithm to recover high‐quality HDRI images from a single, coded exposure. The proposed reconstruction method builds on recently‐introduced ideas of convolutional sparse coding (CSC); this paper demonstrates how to make CSC practical for HDR imaging. We demonstrate that the proposed algorithm achieves higher‐quality reconstructions than alternative methods, we evaluate optical coding schemes, analyze algorithmic parameters, and build a prototype coded HDR camera that demonstrates the utility of convolutional sparse HDRI coding with a custom hardware platform.     

Phase analysis of the ZrO<Subscript>2</Subscript>-GeO<Subscript>2</Subscript> system

This paper presents a physicochemical study of poorly explored compounds in the zirconia-germania system. Reactions between these oxides were investigated by differential scanning calorimetry and thermogravimetry. The morphology of the reaction products was studied by scanning electron microscopy. The reaction products of ZrO₂ and GeO₂ powders were characterized by quantitative phase analysis. X-ray diffraction and Raman spectroscopy data indicate the formation of the germanates Zr₃GeO₈ and ZrGeO₄. These compounds are shown to be substitutional solid solutions, and their homogeneity ranges are determined. GeO₂ dissolution in ZrO₂ stabilizes its tetragonal structure.     

Results from tests of modernized moisture separator-reheater of K-500-65/3000 turbine plants of the power unit No. 4 at the Leningrad Nuclear Power Plants (NPP)

Results from tests of the modernized moisture separator-reheaters MSRs-500-1 with Powervane louvers developed by Balcke-Dürr company are presented. Results fromstudies on the determination of wetness of the heated steam at the outlet from the separating part of the MSR and its temperature between super-heating stages, which demonstrate advantages of modernized MSR are discussed.     

A general method for evaluating the overhead when consolidating servers: performance degradation in virtual machines and containers

The Journal of Supercomputing - Server consolidation is one of the most commonly used techniques for reducing energy consumption in datacenters; however, this results in inherent performance...     

Prevalence of Salmonella spp. and Listeria monocytogenes at small-scale spanish factories producing traditional fermented sausages

The manufacturing of fermented sausages is subject to natural contamination processes that can potentially carry foodborne pathogens along the process chain and result in contamination of the final product. The aim of this study was to evaluate the occurrence of Salmonella spp. and Listeria monocytogenes at different sampling points during the manufacturing process of fuet, a type of traditional fermented sausage, at 10 small-scale Spanish factories. The presence of both pathogens was studied in the raw materials (19 casings and 19 meat batters), the final products (19 fermented sausages), and the factory equipment (12 mincing, 12 mixing, and 19 stuffing machines, 19 cutting tables, 11 knives, and 12 cold rooms) by using classical microbiological techniques and real-time PCR. Salmonella was not detected in the equipment analyzed or in the final products, but it was detected in the raw materials (23.7% of samples). L. monocytogenes showed higher incidence than Salmonella and was detected in the equipment (11.8% of samples), the raw materials (28.9%), and the final products (15.8%), confirming its ubiquity throughout the manufacturing process of fermented sausages. Five factories were further investigated to study the changes in the distribution of pathogens in the fuet production process over a period of either 2 or 3 years. There was considerable variation in the incidence of both pathogens at different sampling periods, and there was no relation between seasonal variations or geographic location of the factories.