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This paper reviews the findings of recent research on the formation of solid splats by the impact of thermal spray particles on solid substrates. It discusses methods of describing the substrate, by characterizing both chemical (oxide layers) and physical (surface topography, adsorbed and condensed contaminants) aspects. Recent experiments done to observe impact of thermal spray particle are surveyed and techniques used to photograph particle impact and measure cooling rates described. The use of numerical modeling to simulate impact and deformation of impacting particles is appraised. Two different break-up mechanisms are identified: solidification around the edges of splats; and perforations in the interior of thin liquid films created by droplet spreading without solidification. These two modes can be reproduced in numerical models by varying the value of thermal contact resistance between the splat and substrate. A simple criterion to predict the final splat shape is presented.

Textbook concisely introduces engineering thermodynamics, covering concepts including energy, entropy, equilibrium and reversibility * Novel explanation of entropy and the second law of thermodynamics * Presents abstract ideas in an easy to understand manner * Includes solved examples and end of chapter problems * Accompanied by a website hosting a solutions manual

An analytical model of the true area of contact between molten metal and a rough, solid surface has been used to calculate thermal contact resistance and to predict how it changes with surface roughness, substrate thermal properties and contact pressure. This analytical model was incorporated into a three-dimensional, time-dependent numerical model of free-surface flows and heat transfer. It was used to simulate impact, spreading and solidification of molten metal droplets on a solid surface while calculating contact resistance distributions at the liquid–solid interface. Simulations were done of the impact of 4 mm diameter molten aluminum alloy droplets and 50 μm diameter plasma sprayed nickel particles on steel plates. Predicted splat shapes were compared with photographs taken in experiments and simulated substrate temperature variation during droplet impact was compared with measurements.

High-velocity impact of water droplets (0.55 mm diameter) on a heated stainless steel surface was photographed. To achieve high impact velocities, the test surface was mounted on the rim of a rotating flywheel, giving linear velocities of up to 50 m s−1. Two cartridge heaters were inserted in the substrate and used to vary substrate temperature. A charge coupled device (CCD) video camera was used to photograph droplets impinging on the substrate. To photograph different stages of droplet impact, the ejection of a single droplet was synchronized with the position of the rotating flywheel and triggering of the camera. Substrate temperature was varied from 100 to 240 °C and the impact velocity from 10 to 30 m s−1. High-resolution photographs were taken of vapour bubbles nucleating sites inside the thin liquid films produced by spreading droplets. An analytical expression was derived for the amount of superheat required for vapour bubble nucleation as a function of the impact velocity. For a given surface roughness, the amount of superheat needed decreased with impact velocity, which agreed with experimental results. For a fixed impact velocity, the maximum extent of droplet spread increased with substrate temperature.

Rupture of liquid films formed during droplet impact on a dry solid surface was studied experimentally. Water droplets (580±70 μm) were photographed as they hit a solid substrate at high velocities (10-30 m s−1). Droplet-substrate wettability was varied over a wide range, from hydrophilic to superhydrophobic, by changing the material of the substrate (glass, Plexiglas, wax and alkylketene dimer). Both smooth and rough wax surfaces were tested. Photographs of impact showed that as the impact velocity increased and the film thickness decreased, films became unstable and ruptured internally through the formation of holes. However, the impact velocity at which rupture occurred was found to first decrease and then increase with the liquid-solid contact angle, with wax showing rupture at all impact velocities tested. A thermodynamic stability analysis combined with a droplet spreading model predicted the rupture behaviour by showing that films would be stable at very small or at very large contact angles, but unstable in between. Film rupture was found to be greatly promoted by surface roughness.

The advancement in deep learning techniques has helped researchers acquire and process multimodal data signals from different healthcare domains. Now, the focus has shifted towards providing end-to-end solutions, i.e., processing these data and developing models that can be directly implemented on edge devices. To achieve this, the researchers try to solve two problems: (I) reduce the complex feature dependencies and (II) reduce the complexity of the deep learning model without compromising accuracy. In this paper, we focus on the later part of reducing the complexity of the model by using the knowledge distillation framework. We have introduced knowledge distillation on the Vision Transformer model to study the MIT-BIH Arrhythmia Database. A tenfold crossvalidation technique was used to validate the model, and we obtained a 99.7% F1 score and 99.3% accuracy. The model was further tested on the Xilinx Alveo U50 FPGA accelerator, and it is found fit for any low-powered wearable device implementation.

Brazed plate heat exchangers (BPHX) are widely used for building cooling and heating systems. To efficiently operate such heat exchangers smart-control software, that used mapped heat transfer curves, was developed and integrated into the system. For precise control of a BPHX it is critical to characterize the actual performance of the BPHXs in the development phase and integrate verified performance correlations into the software. This paper focuses on analytical approaches to determining heat transfer coefficients and estimating heat loads for a brazed plate heat exchanger, and verification of the correlations that were developed with experimental testing according to AHRJ-400 standards. A brazed plate heat exchanger (Model: Z400H-90) was tested with water at varying flow rates. The measured outlet temperatures successfully match predictions and heat transfer coefficients fit well to values extrapolated from correlations in the literature. The experimental results verify that the method developed works well in estimating the performance of brazed plate heat exchangers. The high accuracy of heat transfer predictions allows the performance of the heat exchanger to be optimized by control software using performance maps.

Day by day, the number of blog users and microblog users is increasing worldwide. It is easy to say that blogs have captured a significant portion of other web services. In the past few years, the number of users has exponentially increased. User count of Facebook, Twitter, and Instagram applications is not hidden from anyone. Users on such platforms share ideas, experiences, stories, opinions, and views and want to interact with people with the same set of interests. As per the user’s expectation, there is a requirement of two things: content curation and recommendations. The content curation algorithm will find the people and their posts on personalized search results. In addition, the recommendation system will help to find the most appropriate match to interact with. In this paper, both approaches are combined to show the user’s curated and recommended results. The article focuses on the hybrid model named S-ANFIS, and the results are compared with the well-known approaches like ANN, Deep Neural Network (DNN), and Recurrent Neural Network (RNN).

This study was focused on measuring the properties of twenty-three commercially available coatings formulated for exterior wood applications. The coatings were characterized by measuring their surface tension, solid content, viscosity, pH, and glass transition temperatures (Tg). Additionally, the wetting properties of coating droplets on wood substrates were measured. The contact angle of solvent-based and water-based coatings were characterized on untreated southern yellow pine wood samples using high-resolution image analysis and the Young–Laplace solution. An innovative image processing technique for determining the average diameter of coating droplets on wood was developed, and an iterative method to calculate the average contact angle using the Young–Laplace solution was applied. The water-resistance of the coated wood samples was evaluated during one week of water immersion tests. In general, solvent-based coatings had significantly lower contact angles and water uptake than water-based coatings. Water-based paint samples had the largest average contact angle (81°), and solvent-based transparent penetrating stains had the smallest contact angle (13.9°). A strong correlation was observed between the coating water uptake and their surface tension and solid content.