Modelling of Diesel fuel properties through its surrogates using Perturbed-Chain, Statistical Associating Fluid Theory

The Perturbed-Chain, Statistical Associating Fluid Theory equation of state is utilised to model the effect of pressure and temperature on the density, volatility and viscosity of four Diesel surrogates; these calculated properties are then compared to the properties of several Diesel fuels. Perturbed-Chain, Statistical Associating Fluid Theory calculations are performed using different sources for the pure component parameters. One source utilises literature values obtained from fitting vapour pressure and saturated liquid density data or from correlations based on these parameters. The second source utilises a group contribution method based on the chemical structure of each compound. Both modelling methods deliver similar estimations for surrogate density and volatility that are in close agreement with experimental results obtained at ambient pressure. Surrogate viscosity is calculated using the entropy scaling model with a new mixing rule for calculating mixture model parameters. The closest match of the surrogates to Diesel fuel properties provides mean deviations of 1.7% in density, 2.9% in volatility and 8.3% in viscosity. The Perturbed-Chain, Statistical Associating Fluid Theory results are compared to calculations using the Peng–Robinson equation of state; the greater performance of the Perturbed-Chain, Statistical Associating Fluid Theory approach for calculating fluid properties is demonstrated. Finally, an eight-component surrogate, with properties at high pressure and temperature predicted with the group contribution Perturbed-Chain, Statistical Associating Fluid Theory method, yields the best match for Diesel properties with a combined mean absolute deviation of 7.1% from experimental data found in the literature for conditions up to 373°K and 500 MPa. These results demonstrate the predictive capability of a state-of-the-art equation of state for Diesel fuels at extreme engine operating conditions

Satellite versus ground-based estimates of burned area: a comparison between MODIS based burned area and fire agency reports over North America in 2007

North American wildfire management teams routinely assess burned area on site during firefighting campaigns; meanwhile, satellite observations provide systematic and global burned-area data. Here we compare satellite and ground-based daily burned area for wildfire events for selected large fires across North America in 2007 on daily timescales. In a sample of 26 fires across North America, we found the Global Fire Emissions Database Version 4 (GFED4) estimated about 80% of the burned area logged in ground-based Incident Status Summary (ICS-209) over 8-day analysis windows. Linear regression analysis found a slope between GFED and ICS-209 of 0.67 (with R = 0.96). The agreement between these data sets was found to degrade at short timescales (from R = 0.81 for 4-day to R = 0.55 for 2-day). Furthermore, during large burning days (> 3000 ha) GFED4 typically estimates half of the burned area logged in the ICS-209 estimates

Reduction of Ion Heating During Magnetic Reconnection by Large-Scale Effective Potentials

The physical processes that control the partition of released magnetic energy between electrons and ions during reconnection is explored through particle-in-cell simulations and analytical techniques. We demonstrate that the development of a large-scale parallel electric field and its associated potential controls the relative heating of electrons and ions. The potential develops to restrain heated exhaust electrons and enhances their heating by confining electrons in the region where magnetic energy is released. Simultaneously the potential slows ions entering the exhaust below the Alfv\'enic speed expected from the traditional counterstreaming picture of ion heating. Unexpectedly, the magnitude of the potential and therefore the relative partition of energy between electrons and ions is not a constant but rather depends on the upstream parameters and specifically the upstream electron normalized temperature (electron beta). These findings suggest that the fraction of magnetic energy converted into the total thermal energy may be independent of upstream parameters

When Non-Gaussian States are Gaussian: Generalization of Non-Separability Criterion for Continuous Variables

We present a class of non-Gaussian two-mode continuous variable states for which the separability criterion for Gaussian states can be employed to detect whether they are separable or not. These states reduce to the two-mode Gaussian states as a special case.Comment: Removed 1 figure, added reference

Normative Alethic Pluralism

Some philosophers have argued that truth is a norm of judgement and have provided a variety of formulations of this general thesis. In this paper, I shall side with these philosophers and assume that truth is a norm of judgement. What I am primarily interested in here are two core questions concerning the judgement-truth norm: (i) what are the normative relationships between truth and judgement? And (ii) do these relationships vary or are they constant? I argue for a pluralist picture—what I call Normative Alethic Pluralism (NAP)—according to which (i) there is more than one correct judgement-truth norm and (ii) the normative relationships between truth and judgement vary in relation to the subject matter of the judgement. By means of a comparative analysis of disagreement in three areas of the evaluative domain—refined aesthetics, basic taste and morality—I show that there is an important variability in the normative significance of disagreement—I call this the variability conjecture. By presenting a variation of Lynch’s scope problem for alethic monism, I argue that a monistic approach to the normative function of truth is unable to vindicate the conjecture. I then argue that normative alethic pluralism provides us with a promising model to account for it

Who gets a laboratory positive diagnosis of Mycoplasma pneumoniae: A 10-year retrospective analysis

OBJECTIVE: Mycoplasma pneumoniae (M. pneumoniae) is thought to cause up to a third of community acquired pneumonias (CAP), but may be undiagnosed due to limitations with current diagnostics, and untreated given the frequent use of B-lactams to which M. pneumoniae is not susceptible. We performed a ten-year retrospective analysis to identify the typical characteristics of a patient with a laboratory positive diagnosis of M. pneumoniae. METHODS: Laboratory diagnosis of M. pneumoniae was performed using Polymerase Chain Reaction (PCR) and Serology (passive particle agglutination (PPA) and Enzyme-linked immunosorbent (EIA) assays). Data were collected on all patients tested for M. pneumoniae between 2009 and 2019. RESULTS: 19,090 PCR and 4530 serology samples were tested for M. pneumoniae with 278 positive results. The positive group had a median age of 40 years (interquartile range 30–41 years); Median C-reactive Protein (CRP) was 71 mg/L, White blood Cell Count (WBC) 7 × 10^{9}. 80% had an abnormal Chest X-ray. Intensive Care Unit (ICU) admission occurred in 4.5%; 1.3% patients died. 29% of patients were positive on both serology and PCR testing platforms. CONCLUSIONS: The characteristics reported here could be used as guidance on who is treated for M. pneumoniae. We propose that testing for M. pneumoniae needs to be performed systematically in patients with CAP; and that targeted atypical pathogen cover should be considered in preference to B-lactam mono-therapy for all patients with these characteristics

Simulation of transcritical fluid jets using the PC-SAFT EoS

The present paper describes a numerical framework to simulate transcritical and supercritical flows utilising the compressible form of the Navier–Stokes equations coupled with the Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EoS); both conservative and quasi-conservative formulations have been tested. This molecular model is an alternative to cubic EoS which show low accuracy computing the thermodynamic properties of hydrocarbons at temperatures typical for high pressure injection systems. Liquid density, compressibility, speed of sound, vapour pressures and density derivatives are calculated with more precision when compared to cubic EoS. Advection test cases and shock tube problems are included to show the overall performance of the developed framework employing both formulations. Additionally, two-dimensional simulations of nitrogen and dodecane jets are presented to demonstrate the multidimensional capability of the developed model

Simulation of transcritical Diesel jets using the PC-SAFT EoS

A numerical framework has been developed to simulate Diesel injections using the Perturbed Chain Statistical Associating FluidTheory (PC-SAFT) equation of state (EoS). The Diesel is modelled as a mixture composed by a rather small number of components that accurately replicate its properties. The composition of the Diesel surro-gates employed are divided into two typesdepending on how closely they approximatetherealDiesel composition. Despite of applying anadvanced molecular theory, practical simulations can be performed reducing the number of times the EoSis solved by calculating the pressure and sonic fluid velocity in thecell centers and performing a reconstruction of these variables at the cell faces. Thismethodologyis found to smooth-out the spurious pressure oscillations associated with conservative schemes used along real-fluid EoS.Furthermore, two shock tube prob-lemsarepresentedto validate the hyperbolic part of the numerical frameworkand evaluate how the number of compounds of theDieselsurrogateemployedaffects theaccuracy of the numerical results.Finally,a two-dimen-sional simulation of afour component Diesel surrogate injection is includedto demonstrate the capability of the developed method to predict Diesel fuel-airmixing.Phase separation isbeyond the scope of this research

Silicon web process development

A barrier crucible design which consistently maintains melt stability over long periods of time was successfully tested and used in long growth runs. The pellet feeder for melt replenishment was operated continuously for growth runs of up to 17 hours. The liquid level sensor comprising a laser/sensor system was operated, performed well, and meets the requirements for maintaining liquid level height during growth and melt replenishment. An automated feedback loop connecting the feed mechanism and the liquid level sensing system was designed and constructed and operated successfully for 3.5 hours demonstrating the feasibility of semi-automated dendritic web growth. The sensitivity of the cost of sheet, to variations in capital equipment cost and recycling dendrites was calculated and it was shown that these factors have relatively little impact on sheet cost. Dendrites from web which had gone all the way through the solar cell fabrication process, when melted and grown into web, produce crystals which show no degradation in cell efficiency. Material quality remains high and cells made from web grown at the start, during, and the end of a run from a replenished melt show comparable efficiencies

Tuning Magnetic Avalanches in Mn12-ac

Using micron-sized Hall sensor arrays to obtain time-resolved measurements of the local magnetization, we report a systematic study in the molecular magnet Mn$_{12}$-acetate of magnetic avalanches controllably triggered in different fixed external magnetic fields and for different values of the initial magnetization. The speeds of propagation of the spin-reversal fronts are in good overall agreement with the theory of magnetic deflagration of Garanin and Chudnovsky \cite{Garanin}.Comment: 8 pages, 7 figures; discussion expanded and revise