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

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

La estructura de la cubierta de la pieza de recepción del Centro Especial de Empleo Aspanias. Morales del Vino, Zamora, 1993

The paper describes the wooden structure of a pedestrian bridge of a mixed use building with (residential and working) for disabled people. It has been analyzed from the process of design to the structure itself and questions about materials and treatments. The building was built 13 years ago, when the wooden construction was really reduced in Spain; something to keep in mind in the analysis of this work.El artículo describe el proyecto y la construcción de una estructura de cubierta madera de la pieza de acceso a un edificio de uso mixto residencial y laboral para discapacitados. Se describen algunos aspectos de proyecto, del diseño de la estructura y otros más técnicos relativos al tipo de materiales y tratamientos. La obra se construyó hace unos 13 años, momento en el que en España la construcción con madera era mínima; algo que sin duda no puede perderse de vista al analizar esta obra

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

Use of the point defect model to interpret the iron oxidation kinetics under proton irradiation

This article concerns the study of iron corrosion in wet air under mega-electron-volt proton irradiation for different fluxes at room temperature and with a relative humidity fixed to 45%. Oxidized iron sample surfaces are characterized by ion beam analysis (Rutherford backscattering spectrometry and elastic recoil detection analysis), for the elemental analysis. The structural and physicochemical characterization is performed using the x-ray photoelectron spectroscopy and transmission electron microscopy techniques. We have also measured the iron oxidation kinetics. Radiation enhanced diffusion and transport processes have been evidenced. The modeling of the experimental data shows that the apparent oxygen diffusion coefficient increases whereas the oxygen transport velocity decreases as function of flux. Finally, the point defect model has been used to determine the electric field value in the samples. Results have shown that the transport process can be attributed to the presence of an electrical potential gradient

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

Semiempirical in-cylinder pressure based model for NOx prediction oriented to control applications

This work describes the development of a fast NO X predictive model oriented to engine control in diesel engines. The in-cylinder pressure is the only instantaneous input signal required, along with several mean variables that are available in the ECU during normal engine operation. The proposed model is based on the instantaneous evolution of the heat release rate and the adiabatic flame temperature (both obtained among other parameters from the in-cylinder pressure evolution). Corrections for considering the NO X reduction due to the re-burning mechanism are also included. Finally, the model is used for providing a model-based correction of tabulated values for the NO X emission at the reference conditions. The model exhibits a good behaviour when varying exhaust gas recirculation rate, boost pressure and intake temperature, while changes in the engine speed and injection settings are considered in the tabulated values. Concerning the calculation time, the model is optimised by proposing simplified sub-models to calculate the heat release and the adiabatic flame temperature. The final result is suitable for real time applications since it takes less than a cycle to complete the NO X prediction.Guardiola García, C.; López Sánchez, JJ.; Martín Díaz, J.; García Sarmiento, D. (2011). Semiempirical in-cylinder pressure based model for NOx prediction oriented to control applications. Applied Thermal Engineering. 31(16):3275-3286. doi:10.1016/j.applthermaleng.2011.05.048S32753286311

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

Understanding the Patient Experience with Carcinoid Syndrome: Exit Interviews from a Randomized, Placebo-Controlled Study of Telotristat Ethyl

Purpose: Telotristat ethyl, an oral tryptophan hydroxylase inhibitor, is intended to treat carcinoid syndrome by reducing serotonin production. Telotristat ethyl was evaluated in TELESTAR, a Phase III study for patients who had carcinoid syndrome with at least 4 bowel movements (BMs) per day and who were receiving somatostatin analogue therapy. This interview substudy was conducted to provide insight into the patient experience in TELESTAR and to help understand whether reductions in BM frequency (the primary end point) and other symptoms were clinically meaningful. Methods: Participating sites were asked to invite (before randomization) all eligible patients to telephone interviews scheduled at the end of the double-blind treatment period. Patients and interviewers were blinded to treatment. Findings: All 35 interviewed participants reported diarrhea and/or excessive BMs at baseline. Patients reported that these symptoms negatively affected emotional, social, physical, and occupational well-being. Prespecified criteria for treatment response (achieving ≥ 30% reduction in BM frequency for at least 50% of the days) were met by 8 of 26 patients taking telotristat ethyl and 1 of 9 patients taking placebo. All 8 patients taking telotristat ethyl described clinically meaningful reductions in BM frequency and were very satisfied with the ability of the study drug to control their carcinoid syndrome symptoms. Overall, reports of being very satisfied were observed in 12 patients taking telotristat ethyl and 0 taking placebo. Implications: Patient interviews revealed that TELESTAR patients, at baseline, were significantly affected by their high BM frequency. Patient reports of their clinical trial experience supported the significance of the primary end point and clinical responder analysis in TELESTAR, helping identify and understand clinically meaningful change produced by telotristat ethyl

Instability of the steady states of some Ginzburg–Landau-like equations with real coefficients

The instability of the steady states with nonconstant amplitude is analysed for a nonlocal Ginzburg–Landau equation with real coefficients and quasiperiodic boundary conditions. The results are obtained in terms of easily recognized, qualitative properties of the steady states. Some of the results are new, even for the standard (local) Ginzburg–Landau equation with real coefficients. A related Ginzburg–Landau equation coupled to a mean field is also considered that appears in the analyses of counter-propagating waves in extended systems, nonoscillatory instabilities with a conservation law, and viscous Faraday waves in large aspect ratio containers