Effects of multicomponent diffusion on predicted ignition characteristics of an n-heptane diffusion flame

Flamelet models for turbulent combustion typically employ the assumption of unity Lewis number, i.e., equal thermal and species diffusivities. These models have been employed to predict ignition delay times and ignition location in combusting sprays. However, there is the interesting question: what would be the effects of including multicomponent species diffusion on the ignition predictions? In this work, a one-dimensional n-heptane-air diffusion flame is chosen to study the effects of multicomponent diffusion on predicted ignition characteristics. The ambient conditions selected include typical in-cylinder conditions of a medium-duty diesel engine: pressure 10-40 bar and air temperature 850-1000 K. The ignition and oxidation of n-heptane are predicted using a reaction mechanism consisting of 34 species and 56 steps. The mixture fraction is computed separately as a passive species, the diffusion coefficient, of which is equal to the local thermal diffusion coefficient. From these computations, the transient structure of the flamelet, including ignition, is obtained. The results are compared with those obtained with the unity Lewis number assumption. The implications of the unity Lewis number assumption on the predicted ignition characteristics are discussed.     

Plating on acrylonitrile–butadiene–styrene (ABS) plastic: a review

ABS is an engineering plastic that has butadiene part uniformly distributed over the acrylonitrile-styrene matrix. It possesses excellent toughness, good dimensional stability, easy processing ability, chemical resistance, and cheapness. However, it suffers from inherent shortcomings in terms of mechanical strength and vulnerability to environmental conditions. Furthermore, it is non-conducting and easily fretted. Plating on ABS can serve to enhance the strength and structural integrity as well as to improve durability and thermal resistance resulting in metallic properties on the ABS material. ABS is described as the most suitable candidate for plating because it is possible to deposit an adherent metal coating on it by only the use of chemical pretreatment process and without the use of any mechanical abrasion. This article aims to review the history of ABS plastics, properties of ABS, processes and mechanisms of plating, and studies of plating on ABS involving mainly eco-friendly methods of plating by discussing the literature published in recent years. The details of electroplating of ABS carried out in the authors’ laboratory are also presented.     

The effect of different formulations on physical properties of cakes baked with microwave and near infrared-microwave combinations.

The aim of this study was to determine the effect of different formulations on color and textural characteristics of different cakes during baking in microwave and near infrared-microwave combination ovens. For comparison, cakes were also baked in conventional ovens. Color and hardness for both types of baking schemes were found to be dependent on formulation. Cakes containing Simplesse, a fat replacer consisting mostly of whey protein, baked in microwave and near infrared-microwave combination ovens were found to be the firmest cakes.     

Identification in the presence of classes of unmodeled dynamics andnoise

Identification involves obtaining a model from an a priori chosen model class(es) using finite corrupted data. The corruption may be due to several reasons ranging from noise to unmodeled dynamics, since the real system may not belong to the model class. Two popular approaches-probabilistic and set-membership identification-deal with this problem by imposing temporal constraints on the noise sample paths. We differentiate between the two sources of error by imposing different types of constraints on the corruption. If the source of corruption is noise, we model it by imposing temporal constraints on the possible realizations of noise. On the other hand, if it results from unmodeled dynamics informational constraints are imposed. Contrary to probabilistic identification where the parameters of the identified model converge to the true parameters in the presence of noise, current results in set-membership identification do not have this convergence property. Our approach leads to bridging this gap between probabilistic and set-membership identification when the source of corruption is noise. For the case when both unmodeled dynamics and noise are present, we derive consistency results for the case when the unmodeled dynamics can be described either by a linear time-invariant system or by a static nonlinearity     

Self-excited vibrations of optical microresonators

Microresonators in the form of metal coated silicon dioxide strips have been driven into resonant vibration by the application of unmodulated fibre-guided light. The experiments carried out to observe this phenomenon are described, their results presented and discussed, and the implications for multiplexing microresonators sensors in fibre-optic systems are outlined