•The performance of hydraulic correlations for packed columns is evaluated.•The application fields of the examined models for packed columns are presented.•The Kister GPDC-charts work best for ...pressure drop and flooding point estimation.
Eight correlations for the prediction of pressure drop, liquid hold-up and flooding for packed columns were evaluated in an initial analysis in Wolf-Zoellner et al. 2019. The best predictions were achieved with the Wolf 2014 model and a modified model of Maćkowiak 2003 by Wolf-Zoellner.
The objective of this work is to extend the performance investigation to other well-known correlations available in literature: Spiegel and Maier 1992, Brunazzi 2002, Bozzano 2007, NNA-Model of Piché 2001, GPDC of Kister 2007, Robbins 1991, Jammula 2014.
Therefore, the significant combined databases of the Separation Research Program (SRP) at The University of Texas and the Montanuniversitaet Leoben (MUL) provide the perfect basis to evaluate the correlations. The databases include pressure drop, hold-up and flooding point data for 50 different random (2nd, 3rd and 4th generation) and structured packings (sheet and grid structured packings) for different test systems under absorption and distillation conditions. At present 32 packings are included in the study.
Based on this evaluation, the Kister GPDC-charts show the best agreement for pressure drop and flooding point estimation. Generally, all examined models perform well for pressure drop calculation but none of the considered models are able to predict reliable liquid-hold ups. In addition, the overall poor modelling performance involving viscous liquids is obvious and needs further investigations.
This essay delves into the evolving role of audit engagements in assuring sustainability reports. While traditional and contemporary auditing focus primarily on evaluating financial data and ...governance structures to foster investors’ trust and ensure financial market stability, the recent push for sustainability assurance stretches the auditors’ role much further, requiring them to guide numerous stakeholders in navigating long-term (climate) risks and opportunities. We identify three pitfalls and overpromises in applying contemporary auditing principles to provide sustainability assurance: the feasibility of existing methodologies, the tension between social aspirations and economic realities, and the illusion of pseudo-assurance. These findings offer guidance to auditors and underscore the further need to revisit the paradigmatic foundation of auditing.
THE MATERHORN Fernando, H. J. S.; Pardyjak, E. R.; Di Sabatino, S. ...
Bulletin of the American Meteorological Society,
11/2015, Letnik:
96, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Emerging application areas such as air pollution in megacities, wind energy, urban security, and operation of unmanned aerial vehicles have intensified scientific and societal interest in mountain ...meteorology. To address scientific needs and help improve the prediction of mountain weather, the U.S. Department of Defense has funded a research effort—the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program—that draws the expertise of a multidisciplinary, multiinstitutional, and multinational group of researchers. The program has four principal thrusts, encompassing modeling, experimental, technology, and parameterization components, directed at diagnosing model deficiencies and critical knowledge gaps, conducting experimental studies, and developing tools for model improvements. The access to the Granite Mountain Atmospheric Sciences Testbed of the U.S. Army Dugway Proving Ground, as well as to a suite of conventional and novel high-end airborne and surface measurement platforms, has provided an unprecedented opportunity to investigate phenomena of time scales from a few seconds to a few days, covering spatial extents of tens of kilometers down to millimeters. This article provides an overview of the MATERHORN and a glimpse at its initial findings. Orographic forcing creates a multitude of time-dependent submesoscale phenomena that contribute to the variability of mountain weather at mesoscale. The nexus of predictions by mesoscale model ensembles and observations are described, identifying opportunities for further improvements in mountain weather forecasting.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Research on Venture Capitalists' (VCs) industrial diversification is supplemented with the notion of diversification along an industry's value chain. VCs are hypothesized to create a portfolio of ...complementary investments along the value chain, accompanied by low geographic diversification. Further, VCs specializing in an industry with network externalities are predicted to devote relatively more investments to this industry, followed by an increased propensity for diversification along the value chain. This, subsequently, will result in less geographic diversification. The hypotheses are supported through a study on VCs in the US and Europe. Contributions to the literature on VCs, diversification, geographic agglomeration and network effects are discussed.
•The performance of different fluiddynamic correlations for packed columns is compared.•The application fields of the various hydraulic models for packed columns are revealed.•A modification of the ...Maćkowiak model is introduced which leads to a significantly improved modelling performance.•The paper shows the operating ranges and packing types for which the models provide reliable predictions.•The weaknesses of the various correlations are addressed.
The hydraulic properties of pressure drop, hold-up and flooding point are of immense importance to describe the performance of random and structured packings. Therefore, accurate modelling of these performance parameters over the whole operating range has to be ensured. For this reason, many correlations have been developed by different institutions in the past (Billet and Schultes, 1991, 1999; Wolf, 2014; Engel, 1999; RBF (Rocha, Bravo, Fair), 1993, Delft-model (Olujić) 1997; Verschoof, 1999; Maćkowiak, 2003, Stichlmair, 1989). As these correlations are usually only reliable for validated packings, the purpose of this work is to evaluate these models based on the significant database of the Separation Research Program (SRP) at The University of Texas and the database of Montanuniversitaet Leoben (MUL). Combined, these databases include pressure drop, liquid hold-up and flooding point data for 50 different random and structured packings at different operating conditions. Furthermore, some pressure drop and flooding data obtained from the SRP 43cm diameter distillation column are also used.
In this work, the predictions of the various correlations are compared and the application fields of the various models are revealed. In particular, the paper shows the operating ranges as well as packing types for which the models provide reliable predictions but also the weaknesses of the various correlations. Particularly, a modification of the Maćkowiak model is introduced which leads to a significantly improved modelling performance.
Abstract Neutrophil infiltration and activation in the lung are important pathophysiological features in COPD, severe asthma and bronchiectasis mostly mediated by CXCL8 and CXCL1 via CXCR1 and CXCR2. ...No thorough study to date has been performed to compare the anti-inflammatory effect profile of dual CXCR1/2 vs. selective CXCR2 antagonists in relevant human neutrophil assays and pulmonary inflammation models. Dual CXCR1/2 (SCH527123, diaminocyclobutandione-1) and selective CXCR2 (SB265610, thiopyrimidine-1) antagonist activity and receptor residence time were determined by 35 SGTPγS binding in human ( h )- and guinea pig ( gp )-CXCR1 and CXCR2 overexpressing membranes. h -neutrophil chemotaxis, degranulation and ROS production were established using CXCL8 or CXCL1 to evaluate dual CXCR1/2- or selective CXCR2-dependent activities. LPS-induced lung inflammation in gp was selected to assess in vivo potency. Dual CXCR1/2 antagonists blocked both CXCL8 and CXCL1-induced h -neutrophil functions and 35 SGTPγS binding. In contrary, selective CXCR2 antagonists displayed significantly reduced potency in CXCL8 -mediated h -neutrophil responses despite being active in CXCR2 assays. Upon LPS challenge in gp, administration of SCH527123 inhibited the increase of neutrophils in BALF, modestly reduced blood neutrophils and induced minor neutrophil accumulation in bone marrow. Differentiation of CXCR1/2 vs. CXCR2 antagonists could not be extended to in vivo due to differences in CXCR1 receptor homology between h and gp . Dual CXCR1/2 therapy may represent a promising anti-inflammatory treatment for respiratory diseases reducing more effectively neutrophil migration and activation in the lung than a CXCR2 selective treatment. However, the in vivo confirmation of this claim is still missing due to species differences in CXCR1.
White mold (Sclerotinia sclerotiorum) of leguminous crops in New York is generally managed with preventive applications of fungicides. However, no research has been conducted during the last decade ...to assess the sensitivity of the S. sclerotiorum population to fungicides or compare their performance under field conditions. The sensitivity of S. sclerotiorum to boscalid, fluazinam, and thiophanate-methyl was assessed in 151 isolates from 15 fields across New York using an agar dilution method with discriminatory concentrations. In addition, the effective concentration at which mycelial growth is reduced by 50% (EC
) was estimated for one representative isolate from each field. The efficacy of commercial formulations of each fungicide on white mold incidence in plants and pods was also tested in two field trials (2015 and 2016). The EC
values ranged from 0.068 to 0.219, 0.001 to 0.002, and 1.23 to 2.15 µg/ml for boscalid, fluazinam, and thiophanate-methyl, respectively. Evidence of resistance was not found using the discriminatory concentration tests. The mycelial growth inhibition relative to the control ranged from 56 to 83%, 66 to 84%, and 53 to 83% at discriminatory concentrations of boscalid (5 µg a.i./ml), fluazinam (0.05 µg a.i./ml), and thiophanate-methyl (5 µg a.i./ml), respectively. Fourteen isolates with mycelial growth inhibition lower than 60% at 5 µg/ml of thiophanate-methyl, did not exhibit point mutations within a partial sequence of the β-tubulin gene. In the field trials, fungicides effectively reduced white mold incidence on plants by 75% (2015) and 93% (2016) and on pods by 81% (2015) and 87% (2016), both relative to the nontreated plots. However, fungicide applications led to significant increases in pod yield, relative to the nontreated plots, only in 2015 when the incidence of white mold on plants and pods were higher (85 and 49.2%) than in 2016 (31.3 and 10.3%). Although fungicide resistance was not detected, and thus control failures reported by New York snap bean growers may be due to other factors, further monitoring of sensitivity within the S. sclerotiorum population is encouraged as well as the use of rational systems to base their judicious and economic use.
The Taiwanese-American Occultation Survey (TAOS) aims to detect serendipitous occultations of stars by small (~1 km diameter) objects in the Kuiper Belt and beyond. Such events are very rare (<10 ...super(-3) events per star per year) and short in duration (~200 ms), so many stars must be monitored at a high readout cadence. TAOS monitors typically ~500 stars simultaneously at a 5 Hz readout cadence with four telescopes located at Lulin Observatory in central Taiwan. In this paper, we report the results of the search for small Kuiper Belt objects (KBOs) in seven years of data. No occultation events were found, resulting in a 95% c.l. upper limit on the slope of the faint end of the KBO size distribution of q - 3.34-3.82, depending on the surface density at the break in the size distribution at a diameter of about 90 km.
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