Interaction of diesel engine soot with NO2 and O2 at diesel exhaust conditions. Effect of fuel and engine operation mode

This work shows a study of the reactivity of twelve different types of soot with either NO2 or O2 under reacting conditions typically present in diesel particulate filters (DPFs). The soot samples were obtained from the combustion of four conventional and alternative fuels (diesel, biodiesel and two paraffinic fuels) in a diesel engine bench operated under three different engine operation modes: a typical urban-driving mode and two variations to this mode to assess the effect of the injection settings. The main objective of the work is to relate the oxidative reactivity of the soot to the nature and the origin of each sample. The possible simultaneous elimination of soot and NOx at typical diesel exhaust conditions is examined, as well. The reactivity tests were performed in a laboratory quartz gas flow reactor, discontinuous for the solid. The soot-NO2 interaction was studied with 200 ppm of NO2 at 500 °C and the soot-O2 interaction was studied with 5% O2 at 500 °C and 600 °C. The experimental results were used to determine the time needed for the complete conversion of carbon (t) through the use of the equations of the Shrinking Core Model for solid-gas reactions with decreasing size particle and chemical reaction control. In general, the t values show that the diesel fuel generates a less reactive soot than biodiesel or the alternative paraffinic fuels. In addition, increasing the injection pressure or adding a post-injection to the original injection strategy generates a more reactive soot. These findings point out that there is potential to achieve efficient regeneration processes in DPFs through other fuels than conventional ones and via engine calibration

The Hopkins Verbal Learning Test and screening for dementia

The present study investigated the sensitivity and specificity of the Hopkins Verbal Learning Test (HVLT) for demented patients (n=82, using NINCDS criteria) and 114 healthy controls - equivalent in age, years of education and gender–ratio - from the Oxford Project To Investigate Memory and Ageing. The HVLT ‘Total recall’ score had 87% sensitivity and 98% specificity for dementia using a cut-off score of 14.5. Using a 'Memory' score (the sum of the 'Total Recall' and the 'Discrimination Index') with a cutoff score of 24.5 gave a 91% sensitivity and 98% specificity for Alzheimer’s disease cases when compared to controls. Unlike the MMSE, the HVLT has no ceiling effects and does not have to be adjusted for education. We conclude that the HVLT is an easy to administer, quick and well tolerated tool for the screening of dementia

Stabilization of Tollmien-Schlichting Waves by Mode Interaction

Decreasing skin friction in boundary layers attached to aircraft wings can have an impact in both fuel consumption and pollutant production, which are becoming crucial to reduce operation costs and meet environmental regulations, respectively. Skin friction in turbulent boundary layers is about ten times that of laminar boundary layers. Thus, an obvious method to reduce friction drag is to delay transition to turbulence, which is a fairly involved process in real aircraft wings [J98]. Transition sis promoted either by Tollmien—Schlichting (TS) and Klebanov (K) modes [K94], with the former playing an essential role. Various methods (e.g., suction [SG00,ZLB04], wave cancellation [WAA01,LG06]) have been proposed to reduce TS modes in laminar boundary layers. Mode interaction methods have been successfully used in fluid systems to control related instabilities, such as the Rayleigh—Taylor instability [LMV01]. Here, we present some recent results on using these methods to control TS modes in a compressible, 2D boundary layer over a flat plate at zero incidence. A given unstable TS mode can be stabilized by coupling its spatial evolution with that of a second selected stable TS mode, in such a way that the stable mode takes energy from the unstable one and gives a stable coupled evolution of both modes. The coupling device is a wavetrain in the boundary layer, with appropriate wavenumber and frequency, which can be created by an array of oscillators on the wall, and promotes both (i) parametric coupling between the stable and unstable TS modes and (ii) a mean flow that is also stabilizing. Three differences with wave cancelation methods are relevant. Namely, (a) nonlinear terms play an essential role in the process; (b) the unstable TS mode is stabilized (its growth rate is decreased), not just canceled; and (c) stabilization does not depend on the phase of the incoming wave, which implies that active control is not necessary

Ideales igualitarios y planes tradicionales: análisis de parejas primerizas en España

Esta investigación analiza los planes de cuidado del primer hijo en parejas, indagando en cómo influyen los ideales de maternidad/ paternidad, las actitudes de género y las limitaciones institucionales en el proyecto de cuidado del bebé. El estudio se basa en una muestra de 68 parejas de doble ingreso que esperaban su primer hijo en el año 2011. El análisis revela que gran parte de las parejas aspira a que ambos cónyuges continúen trabajando después del parto. Sin embargo, en el caso de prever dificultades de conciliación, siguen siendo las mujeres quienes manifiestan una mayor predisposición a adaptar su vida laboral a las necesidades del menor, desarrollando en gran medida preferencias adaptativas

Adaptive determination of cut-off frequencies for filtering the in-cylinder pressure in diesel engines combustion analysis

[EN] In-cylinder pressure analysis is a key tool for engine research and diagnosis and it has been object of study from the beginning of the internal combustion engines. One of its most useful application is combustion analysis on the basis of the First Law of Thermodynamics. However, heat release law calculations use the in-cylinder pressure derivative signal. Hence, the noise is increased and pressure filtering becomes necessary to remove high frequency noise, thus allowing for accurate combustion analyses. In this work, a methodology to set the cut-off frequency of a low-pass filter is proposed. Statistical criteria are used to separate the signal from the noise through the calculation of the Discrete Fourier Transform of several consecutive in-cylinder pressures cycles. Thus, only physically meaningful information is preserved. The proposed methodology is compared with some adaptive and non-adaptive algorithms used to select the cut-off frequencies, and it shows a good ability to adapt to different engine operating conditions. © 2011 Elsevier Ltd. All rights reserved.The authors thank the Universidad Politécnica de Valencia (PAID-06-09) and Generalitat Valenciana (GV/2010/045) for its valuable support to this work.Payri González, F.; Olmeda González, PC.; Guardiola García, C.; Martín Díaz, J. (2011). Adaptive determination of cut-off frequencies for filtering the in-cylinder pressure in diesel engines combustion analysis. Applied Thermal Engineering. 31:2869-2876. https://doi.org/10.1016/j.applthermaleng.2011.05.012S286928763

Experimental assessment for instantaneous temperature and heat flux measurements under Diesel motored engine conditions

The main goal of this work is to validate an innovative experimental facility and to establish a methodology to evaluate the influence of some of the engine parameters on local engine heat transfer behaviour under motored steady-state conditions. Instantaneous temperature measurements have been performed in order to estimate heat fluxes on a modified Diesel single cylinder combustion chamber. This study was divided into two main parts. The first one was the design and setting on of an experimental bench to reproduce Diesel conditions and perform local-instantaneous temperature measurements along the walls of the combustion chamber by means of fast response thermocouples. The second one was the development of a procedure for temperature signal treatment and local heat flux calculation based on one-dimensional Fourier analysis. A thermodynamic diagnosis model has been employed to characterise the modified engine with the new designed chamber. As a result of the measured data coherent findings have been obtained in order to understand local behaviour of heat transfer in an internal combustion engine, and the influence of engine parameters on local instantaneous temperature and heat flux, have been analysed. © 2011 Elsevier Ltd. All rights reserved.Torregrosa, AJ.; Bermúdez, V.; Olmeda González, PC.; Figueroa Garcia, OL. (2012). Experimental assessment for instantaneous temperature and heat flux measurements under Diesel motored engine conditions. Energy Conversion and Management. 54(1):57-66. doi:10.1016/j.enconman.2011.10.009S576654

Insights Into Patients' Experience With Type 1 Diabetes: Exit Interviews From Phase III Studies of Sotagliflozin

Purpose: The purpose of this study was to conduct qualitative participant interviews to provide context to the meaningfulness of improvements in end points seen in 2 large-scale Phase III sotagliflozin trials in participants with type 1 diabetes. Methods: Participants were eligible for an interview if they had exited one of the clinical trials within the previous 12 months. Participants were recruited by investigators at the clinical trial sites, and interviews were conducted by independent interviewers by telephone in accordance with a semistructured interview guide. Both interviewers and participants were blinded to treatment assignment. Qualitative analysis was conducted using ATLAS-ti version 7.5, and descriptive statistics were computed and summarized. Findings: Across 3 countries, 41 participants were interviewed. Difficulty maintaining blood glucose within a desired range, described by participants as lack of blood glucose “stability,” was the most concerning symptom that they reported, wanting to see it improved during the clinical trial because it negatively impacted their physical, mental, and emotional lives. Participants who reported symptom improvement also reported a positive psychosocial impact while taking the clinical trial medication. All participants who monitored ketones described themselves as being “pretty confident” to “very confident” that they could avoid diabetic ketoacidosis by monitoring both ketone levels and understanding the physical signs and symptoms of hyperglycemia. Implications: Improvements in glucose stability and control were important to participants with type 1 diabetes, as these improvements were correlated with improvements in the participants' lives. ClinicalTrials.gov identifiers: NCT02384941; NCT02421510