High order effects in one step reaction sheet jump conditions for premixed flames

The differences need to be understood between the leading order jump conditions, often assumed at a flame sheet in combustion theory, and the actual effect of a one step chemical reaction governed by Arrhenius kinetics. These differences are higher order in terms of a large activation temperature analysis and can be estimated using an asymptotic approach. This paper derives one order of asymptotic correction to the leading order jump conditions that are normally used for describing premixed laminar combustion, providing additional contributions that are due to curvature, flow through the flame sheet and the temperature gradient into the burnt gas. As well as offering more accurate asymptotic results, these can be used to estimate the errors that are inherent in adopting only the leading order version and they can point towards major qualitative changes that can occur at finite activation temperatures in some cases. Applied to steady non-adiabatic flame balls it is found that the effect of a non-zero temperature gradient in the burnt gas provokes the most serious deficiency in the asymptotic approach.<br/

The Challenges of Creativity in Software Organizations

Part 1: Creating ValueInternational audienceManaging creativity has proven to be one of the most important drivers in software development and use. The continuous changing market environment drives companies like Google, SAS Institute and LEGO to focus on creativity as an increasing necessity when competing through sustained innovations. However, creativity in the information systems (IS) environment is a challenge for most organizations that is primarily caused by not knowing how to strategize creative processes in relation to IS strategies, thus, causing companies to act ad hoc in their creative endeavors. In this paper, we address the organizational challenges of creativity in software organizations. Grounded in a previous literature review and a rigorous selection process, we identify and present a model of seven important factors for creativity in software organizations. From these factors, we identify 21 challenges that software organizations experience when embarking on creative endeavors and transfer them into a comprehensive framework. Using an interpretive research study, we further study the framework by analyzing how the challenges are integrated in 27 software organizations. Practitioners can use this study to gain a deeper understanding of creativity in their own business while researchers can use the framework to gain insight while conducting interpretive field studies of managing creativity

Relations between Financing and Output in the Not-for-Profit Hospital

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68639/2/10.1177_107755878804500204.pd

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

On mass conservation in least squares methods

We compare three least-squares finite element reformulations of the Stokes equations, paying particular attention to mass conservation. The first problem we approximate has a simple analytical solution over a convex region. Even for this simple problem, without special treatment of the conservation of mass term, very poor numerical solutions may result. Sufficiently weighting this term leads to a dramatic improvement in the results over a range of test problems

Reaction-sheet jump conditions in premixed flames

The fundamental differences between the leading-order jump conditions, often assumed at a flame sheet in combustion theory, and the actual effect of a chemical reaction that satisfies Arrhenius kinetics with a finite activation temperature, need to be understood. These differences are "higher order" in terms of a large activation temperature analysis. However, they do provide a quantitative estimate of the errors that are inherent in adopting only the leading order version and they can indicate qualitative changes that may occur at finite activation temperatures in some cases. This paper derives two orders of asymptotic correction to the jump conditions normally used in describing premixed laminar combustion. An example involving steady, non-adiabatic flame-balls shows that the accepted asymptotic picture is limited to unusually large Zel'dovich numbers

Flame ball with thermally sensitive intermediate kinetics

Spherical flame balls are studied using a model for the chemical kinetics which involves a non-exothermic autocatalytic reaction, describing the chain-branching generation of a chemical radical and an exothermic completion reaction, the rate of which does not depend on temperature. When the chain-branching reaction has a large activation temperature, an asymptotic structure emerges in which the branching reaction generates radicals and consumes fuel at a thin flame interface, although heat is produced and radicals are consumed on a more distributed scale. Another model, based more simply, but less realistically, on the generation of radicals by decomposition of the fuel, provides exactly the same leading order matching conditions. These can be expressed in terms of jump conditions across a reaction sheet that are linear in the dependent variables and their normal gradients. Using these jump conditions, a reactive–diffusive model with linear heat loss then leads to analytical solutions that are multivalued for small enough levels of heat loss, having either a larger or a smaller radius of the interface where fuel is consumed. The same properties are found, numerically, to persist as the activation temperature of the branching reaction is reduced to values that seem to be typical for hydrocarbon chemistry. Part of the solution branch with larger radius is shown to become stable for low enough values of the Lewis number of the fuel