An experimental and numerical analysis of the influence of the inlet temperature,equivalence ratio and compression ratio on the HCCI auto-ignition process of Primary Reference Fuels in an engine

In order to understand better the auto-ignition process in an HCCI engine, the influence of some important parameters on the auto-ignition is investigated. The inlet temperature, the equivalence ratio and the compression ratio were varied and their influence on the pressure, the heat release and the ignition delays were measured. The inlet temperature was changed from 25 to 70 °C and the equivalence ratio from 0.18 to 0.41, while the compression ratio varied from 6 to 13.5. The fuels that were investigated were PRF40 and n-heptane. These three parameters appeared to decrease the ignition delays, with the inlet temperature having the least influence and the compression ratio the most. A previously experimentally validated reduced surrogate mechanism, for mixtures of n-heptane, iso-octane and toluene, has been used to explain observations of the auto-ignition process. The same kinetic mechanism is used to better understand the underlying chemical and physical phenomena that make the influence of a certain parameter change according to the operating conditions. This can be useful for the control of the auto-ignition process in an HCCI engine.     

High gas permselectivity in ZIF-302/polyimide self-consistent mixed-matrix membrane

Zeolitic imidazolate framework-302 (ZIF-302) was incorporated within a polyimide (PI) matrix in order to develop a highly selective and permeable mixed-matrix membrane (MMM) for gas separation processes. On the basis of varying fabrication procedures, two different MMMs were formed: a dense MMM (ZIF-302/d-PI) and a spongy, self-consistent MMM (ZIF-302/s-PI). The spongy membrane was shown to have self-consistent and disconnected pores with a reduction in overall membrane density. For ZIF-302/d-PI, a 1.2–1.5-fold increase in the permeability of H₂, O₂, N₂, CO₂, and CH₄ was observed when compared with the pure d-PI membrane. For ZIF-302/s-PI, even better improvements (up to 19-fold higher) in permeance were achieved with negligible effects on selectivity. The gas transport mechanism was then analyzed and showed a considerable enhancement of diffusion coefficients for ZIF-302/s-PI, while ideal gas pair selectivities for CO₂/N₂, H₂/CH₄, and H₂/N₂ were found to be 24.8, 42.3, and 62.6, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48513.     

Pd/Al2O3 composite hollow fibre membranes: Effect of substrate resistances on H2 permeation properties

Al₂O₃ hollow fibres with different asymmetric macrostructures, i.e. various thickness ratios between a finger-like layer and a sponge-like layer, have been prepared by a phase inversion/sintering technique. Such asymmetric hollow fibres are used as substrates on which Pd membrane is deposited directly by an electroless plating (ELP) technique without any pre-treatment on substrate surface. Influences of the substrate macrostructure on hydrogen permeation through the Pd/Al₂O₃ composite membranes have been investigated both experimentally and theoretically. The hydrogen permeation through the Pd/Al₂O₃ composite membranes was not only determined by the Pd membrane thickness, but also by the macrostructural parameters of the substrate, such as effective porosity, mean pore size and pore size distribution etc. The thinner the Pd membrane, the higher the effective porosity is required to alleviate the substrate effect on the hydrogen permeation. Also, the deviation of the pore size is suggested to be around 1.2 for the further improved hydrogen permeation through the composite hollow fibre membranes.     

An experimental and numerical analysis of the HCCI auto-ignition process of primary reference fuels,toluene reference fuels and diesel fuel in an engine,varying the engine parameters

For a future HCCI engine to operate under conditions that adhere to environmental restrictions, reducing fuel consumption and maintaining or increasing at the same time the engine efficiency, the choice of the fuel is crucial. For this purpose, this paper presents an auto-ignition investigation concerning the primary reference fuels, toluene reference fuels and diesel fuel, in order to study the effect of linear alkanes, branched alkanes and aromatics on the auto-ignition. The auto-ignition of these fuels has been studied at inlet temperatures from 25 to 120 °C, at equivalence ratios from 0.18 to 0.53 and at compression ratios from 6 to 13.5, in order to extend the range of investigation and to assess the usability of these parameters to control the auto-ignition. It appeared that both iso-octane and toluene delayed the ignition with respect to n-heptane, while toluene has the strongest effect. This means that aromatics have higher inhibiting effects than branched alkanes. In an increasing order, the inlet temperature, equivalence ratio and compression ratio had a promoting effect on the ignition delays. A previously experimentally validated reduced surrogate mechanism, for mixtures of n-heptane, iso-octane and toluene, has been used to explain observations of the auto-ignition process.     

Radon progeny microdosimetry in human and rat bronchial airways: the effect of crossfire from the alveolar region

The objectives of the present study were (1) to present a comprehensiveanalysis of the microdosimetric quantities in both human andrat bronchial airways and (2) to assess the contribution ofthe crossfire alpha particles emitted from the alveolar regionto bronchial absorbed doses. Hit frequencies, absorbed dosesand critical microdosimetric quantities were calculated forbasal and secretory cell nuclei located at different depthsin epithelial tissue for each bronchial airway generation fordefined exposure conditions. Total absorbed doses and hit frequencieswere slightly higher in rat airways than in corresponding humanairways. This confirms the a priori assumption in rat inhalationexperiments that the rat lung is a suitable surrogate for thehuman lung. While the contribution of crossfire alpha particlesis insignificant in the human lung, it can reach 33% in peripheralbronchiolar airways of the rat lung. The latter contributionmay even further increase with increasing alveolar ²¹⁴Po activities.Hence, the observed prevalence of tumors in the bronchiolarregion of the rat lung may partly be attributed to the high-linearenergy transfer crossfire alpha particles.     

Passive detection of image forgery using DCT and local binary pattern

With the development of easy-to-use and sophisticated image editing software, the alteration of the contents of digital images has become very easy to do and hard to detect. A digital image is a very rich source of information and can capture any event perfectly, but because of this reason, its authenticity is questionable. In this paper, a novel passive image forgery detection method is proposed based on local binary pattern (LBP) and discrete cosine transform (DCT) to detect copy–move and splicing forgeries. First, from the chrominance component of the input image, discriminative localized features are extracted by applying 2D DCT in LBP space. Then, support vector machine is used for detection. Experiments carried out on three image forgery benchmark datasets demonstrate the superiority of the method over recent methods in terms of detection accuracy.     

Polarization and Corrosion Studies of Porous and Solid Anodes for Implantable Power-Generating Electrodes

An implantable power source for driving a pacemaker consisting of a hybrid cell utilizing a sacrificial porous aluminum anode and a catalytic cathode for reducing oxygen is considered. Porous aluminum anodes show a significant improvement in polarization over a solid aluminum anode under in vitro transient operating conditions found with certain types of pacemakers. However, the in vivo transient behavior of porous aluminum anodes is only slightly better than solid aluminum anodes. Using in vivo and in vitro linear polarization studies, the corrosion of solid aluminum has been determined to be more than an order of magnitude less than that of solid zinc. The weight loss of aluminum due to corrosion is less than 3.0 percent that of the aluminum needed to supply the faradaic current to the pacemaker. A hybrid cell consisting of an aluminum anode and a porous palladium-black cathode has powered a commercially available pacemaker. Further histopathologic evaluation of tissues surrounding anodes is needed before selecting either zinc or aluminum as an anode material.     

Numerical Investigation of Multi-scale Characteristics of Single and Multi-layered Woven Structures

Applied Composite Materials - Resin flow through multi-ply woven fabrics is affected by the fibre orientation and laminate stacking sequence during the impregnation process. This is characterised...