Comparison of different techniques for characterizing the diesel injector internal dimensions

[EN] The geometry of certain parts of diesel injectors is key to the injection, atomization and fuel-air mixing phenomena. Small variations on the geometrical parameters may have a strong influence on the aforementioned processes. Thus, OEMs need to assess their manufacturing tolerances, whereas researchers in the field (both experimentalists and modelers) rely on the accuracy of a certain metrology technique for their studies. In the current paper, an investigation of the capability of different experimental techniques to determine the geometry of a modern diesel fuel injector has been performed. For this purpose, three main elements of the injector have been evaluated: the control volume inlet and outlet orifices, together with the nozzle orifices. While the direct observation of the samples through an optical microscope is only possible for the simplest pieces, both Computed Tomography Scanning and the visualization of silicone molds technique have proven their ability to characterize the most complex internal shapes corresponding to the internal injector elements. Indeed, results indicate that the differences observed among these methodologies for the determination of the control volume inlet orifice diameter and the nozzle orifice dimensions are smaller than the uncertainties related to the experimental techniques, showing that they are both equally accurate. This implies that the choice of a given technique for the particular application of determining the geometry of diesel injectors can be done on the basis of availability, intrusion and costs, rather than on its accuracy.This work was partly sponsored by "Ministerio de Economia y Competitividad", of the Spanish Government, in the frame of the Project "Estudio de la interaccion chorro-pared en condiciones realistas de motor", Reference TRA2015-67679-c2-1-R.Salvador, FJ.; Gimeno, J.; De La Morena, J.; Carreres, M. (2018). Comparison of different techniques for characterizing the diesel injector internal dimensions. Experimental Techniques. 42(5):467-472. https://doi.org/10.1007/s40799-018-0246-1S467472425Mobasheri R, Peng Z, Mostafa S (2012) Analysis the effect of advanced injection strategies on engine performance and pollutant emissions in a heavy duty DI-diesel engine by CFD modeling. 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Int J Heat Fluid Flow 32(1):273–284Koukouvinis P, Gavaises M, Li J, Wang L (2016) Large Eddy simulation of diesel injector including cavitation effects and correlation to erosion damage. Fuel 175:26–39Som S, Aggarwal SK (2010) Effects of primary breakup modeling on spray and combustion characteristics of compression ignition engines. Combust Flame 157(6):1179–1193Salvador FJ, De la Morena J, Martínez-López J, Jaramillo D (2017) Assessment of compressibility effects on internal nozzle flow in diesel injectors at very high injection pressures. Energy Convers Manag 132:221–230Salvador FJ, Gimeno J, de la Morena J, Martí-Aldaraví P (2012) Using one-dimensional modelling to analyze the influence of the use of biodiesels on the dynamic behaviour of solenoid-operated injectors in common rail systems: Results of the simulation and discussion. 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Metal island film-based structures for sensing using spectrophotometry and ellipsometry

Metal island films (MIF) are good candidates for sensors due to the strong sensitivity of the localised surface plasmon resonance to the environment refractive index. The strong near field enhancement in the vicinity of the island surface can be even higher if a metal layer (ML) is placed close to a MIF. Structures containing MIF with and without ML are prepared and sensitivities of spectrophotometric and ellipsometric features of the measurements are compared. It is shown that simple MIF is preferable for ellipsometry-based sensing and the one including ML in the case of spectrophotometric measurements

Microstructural and strength study of MIG welded joints of AW7020 aluminium alloy, as a function of joint geometry

[EN] Medium strength AW7XXX aluminium alloys are widely used as welded structures and in transportation. The applications of these alloys are limited by the behaviour of the welded joints. There is no agreement on the joint geometry that must be used on 5 mm welds. The microhardness evolution is one of the most important strength indicators. For this reason, the aim of this work is to study the influence of welded joint geometry on microhardness profile and on the microstructure of a MIG welded AW7020 aluminium alloy, using AW5256 filler.Bloem, C.; Salvador Moya, MD.; Amigó, V.; Vicente-Escuder, Á. (2000). Microstructural and strength study of MIG welded joints of AW7020 aluminium alloy, as a function of joint geometry. Welding International. 14(12):970-974. doi:10.1080/09507110009549300S970974141

Dark Matter Angular Momentum Profile from the Jeans Equation

Cosmological simulations of dark matter structures have shown that the equilibrated dark matter structures have a fairly small angular momentum. It appears from these N-body simulations that the radial profile of the angular momentum has an almost universal behavior, even if the different dark matter structures have experienced very different formation and merger histories. We suggest a perturbed Jeans equation, which includes a rotational term. This is done under a reasonable assumed form of the change in the distribution function. By conjecturing that the (new) subdominant rotation term must be proportional to the (old) dominant mass term, we find a clear connection, which is in rather good agreement with the results of recent high resolution simulations. We also present a new connection between the radial profiles of the angular momentum and the velocity anisotropy, which is also in fair agreement with numerical findings. Finally we show how the spin parameter $\lambda$ increases as a function of radius.Comment: 9 pages, 10 figures, accepted for publication in ApJ, Added reference

Ferulic acid: a key component in grass lignocellulose recalcitrance to hydrolysis

In the near future, grasses must provide most of the biomass for the production of renewable fuels. However, grass cell walls are characterized by a large quantity of hydroxycinnamic acids such as ferulic and p-coumaric acids, which are thought to reduce the biomass saccharification. Ferulic acid (FA) binds to lignin, polysaccharides and structural proteins of grass cell walls cross-linking these components. A controlled reduction of FA level or of FA cross-linkages in plants of industrial interest can improve the production of cellulosic ethanol. Here, we review the biosynthesis and roles of FA in cell wall architecture and in grass biomass recalcitrance to enzyme hydrolysis

Magnitude of terminological bias in international health services research: a disambiguation analysis in mental health

Aims Health services research (HSR) is affected by a widespread problem related to service terminology including non-commensurability (using different units of analysis for comparisons) and terminological unclarity due to ambiguity and vagueness of terms. The aim of this study was to identify the magnitude of the terminological bias in health and social services research and health economics by applying an international classification system. Methods This study, that was part of the PECUNIA project, followed an ontoterminology approach (disambiguation of technical and scientific terms using a taxonomy and a glossary of terms). A listing of 56 types of health and social services relevant for mental health was compiled from a systematic review of the literature and feedback provided by 29 experts in six European countries. The disambiguation of terms was performed using an ontology-based classification of services (Description and Evaluation of Services and DirectoriEs – DESDE), and its glossary of terms. The analysis focused on the commensurability and the clarity of definitions according to the reference classification system. Interrater reliability was analysed using κ. Results The disambiguation revealed that only 13 terms (23%) of the 56 services selected were accurate. Six terms (11%) were confusing as they did not correspond to services as defined in the reference classification system (non-commensurability bias), 27 (48%) did not include a clear definition of the target population for which the service was intended, and the definition of types of services was unclear in 59% of the terms: 15 were ambiguous and 11 vague. The κ analyses were significant for agreements in unit of analysis and assignment of DESDE codes and very high in definition of target population. Conclusions Service terminology is a source of systematic bias in health service research, and certainly in mental healthcare. The magnitude of the problem is substantial. This finding has major implications for the international comparability of resource use in health economics, quality and equality research. The approach presented in this paper contributes to minimise differentiation between services by taking into account key features such as target population, care setting, main activities and type and number of professionals among others. This approach also contributes to support financial incentives for effective health promotion and disease prevention. A detailed analysis of services in terms of cost measurement for economic evaluations reveals the necessity and usefulness of defining services using a coding system and taxonomical criteria rather than by ‘text-based descriptions’

Integrated Visualization of Human Brain Connectome Data

Visualization plays a vital role in the analysis of multi-modal neuroimaging data. A major challenge in neuroimaging visualization is how to integrate structural, functional and connectivity data to form a comprehensive visual context for data exploration, quality control, and hypothesis discovery. We develop a new integrated visualization solution for brain imaging data by combining scientific and information visualization techniques within the context of the same anatomic structure. New surface texture techniques are developed to map non-spatial attributes onto the brain surfaces from MRI scans. Two types of non-spatial information are represented: (1) time-series data from resting-state functional MRI measuring brain activation; (2) network properties derived from structural connectivity data for different groups of subjects, which may help guide the detection of differentiation features. Through visual exploration, this integrated solution can help identify brain regions with highly correlated functional activations as well as their activation patterns. Visual detection of differentiation features can also potentially discover image based phenotypic biomarkers for brain diseases

Assessment of the potential in vivo ecotoxicity of Double-Walled Carbon Nanotubes (DWNTs) in water, using the amphibian Ambystoma mexicanum

Because of their specific properties (mechanical, electrical, etc), carbon nanotubes (CNTs) are being assessed for inclusion in many manufactured products. Due to their massive production and number of potential applications, the impact of CNTs on the environment must be taken into consideration. The present investigation evaluates the ecotoxic potential of CNTs in the amphibian larvae (Ambystoma mexicanum). Acute toxicity and genotoxicity were analysed after 12 days of exposure in laboratory conditions. The genotoxic effects were analysed by scoring the micronucleated erythrocytes in the circulating blood of the larvae according to the French standard micronucleus assay. The results obtained in the present study demonstrated that CNTs are neither acutely toxic nor genotoxic to larvae whatever the CNTs concentration in the water, although black masses of CNTs were observed inside the gut. In the increasing economical context of CNTs, complementary studies must be undertaken, especially including mechanistic and environmental investigations

Density profiles of dark matter haloes: diversity and dependence on environment

(Abridged) We study the outer density profiles of dark matter haloes predicted by a generalized secondary infall model and observed in a N-body cosmological simulation of a \Lambda CDM model. We find substantial systematic variations in shapes and concentrations of the halo profiles as well as a strong correlation of the profiles with the environment. In the N-body simulation, the average outer slope of the density profiles, \beta (\rho\propto r^{-\beta}), of isolated haloes is \approx 2.9; 68% of these haloes have values of \beta between 2.5 and 3.8. Haloes in dense environments of clusters are more concentrated and exhibit a broad distribution of \beta with values larger than for isolated haloes . Contrary to what one may expect, the haloes contained within groups and galaxy systems are less concentrated and have flatter outer density profiles than the isolated haloes. The concentration decreases with M_h, but its scatter for a given mass is substantial. The mass and circular velocity of the haloes are strongly correlated: M_h \propto V_m^{\alpha} with \alpha ~ 3.3 (isolated) and ~3.5 (haloes in clusters). For M_h=10^12M_sun the rms deviations from these relations are \Delta logM_h=0.12 and 0.18, respectively. Approximately 30% of the haloes are contained within larger haloes or have massive companions (larger than ~0.3 the mass of the current halo) within 3 virial radii. The remaining 70% of the haloes are isolated objects. The distribution of \beta as well as the concentration-mass and M_h-V_m relations for the isolated haloes agree very well with the predictions of our seminumerical approach which is based on a generalization of the secondary infall model and on the extended Press-Schechter formalism.Comment: 14 pages, 11 figures included, uses mn.sty, accepted by MNRAS. Minor modifications, new and updated reference