Effect of twin-boundaries on melting of aluminum

Molecular dynamics simulation technique has been applied to investigate melting temperature of aluminum. Semi-empirical potentials, based on the embedded atom method have been employed to calculate lattice parameter, energy per atom and mean square displacements. Melting temperature is found to compare well with the experimental results. Computer simulation studies of some low index (111), (113) and (112) twin boundaries at various temperatures and their effect on the melting temperature are also carried out. It is observed in this study that in the presence of twin boundaries, aluminum melts at lower temperatures, as compared to normal melting point.     

A Bayesian assessment of the PCB temporal trends in Lake Erie fish communities

The temporal trends of polychlorinated biphenyls (PCBs) in Lake Erie fish were evaluated using 30 years of fish contaminant data (1977–2007). The first step of our statistical analysis was based on simple exponential decay models parameterized with Bayesian inference techniques to assess the declining rates in four intensively sampled fish species, i.e., walleye (Stizostedion vitreum), coho salmon (Oncorhynchus kisutch), rainbow trout (Oncorhynchus mykiss) and white bass (Morone chrysops). Because the exponential model postulates monotonic decrease of the PCB levels, we included first- or second-order random error terms in our statistical formulations to accommodate non-monotonic patterns in the dataset studied. Generally, our results suggest that the PCBs have been decreasing over the last 30 years with relatively weak rates that vary among the different fish species examined. Yet, our analysis with the exponential decay model also identified an increasing trend in the PCB concentrations of walleye skinless–boneless filet data, which is manifested after the mid-90s. In the second step, we used dynamic linear modeling (DLM) analysis to account for the fact that the fish length covaries with the PCB concentrations and that different sized fish may have been sampled over time. Our DLM analysis suggests that the previously reported trend of the walleye filet data is actually an artifact associated with the bias of the fish sampling practices followed. The coho salmon and rainbow trout PCB concentrations have been decreasing steadily during the study period but the associated rates were relatively weak. Finally, the PCB trends in white bass appear to have been stabilized over that last decade, although the robustness of this result remains to be confirmed due to the temporal inconsistencies of the information used. We conclude by emphasizing the importance of explicitly accounting for the different covariates (e.g., length, age, lipid content) that can potentially hamper the detection of the actual temporal trends of fish contaminants.     

Peristaltic flow in an asymmetric channel with convective boundary conditions and Joule heating

The peristaltic transport of viscous fluid in an asymmetric channel is concentrated. The channel walls exhibit convective boundary conditions. Both cases of hydrodynamic and magnetohydrodynamic（MHD） fluids are considered. Mathematical analysis has been presented in a wave frame of reference. The resulting problems are non-dimensionalized. Long wavelength and low Reynolds number approximations are employed. Joule heating effect on the thermal equation is retained. Analytic solutions for stream function and temperature are constructed. Numerical integration is carried out for pressure rise per wavelength. Effects of influential flow parameters have been pointed out through graphs.     

High-Temperature Creep and Oxidation Behavior of Mo-Si-B Alloys with High Ti Contents

Multiphase alloys in the Mo-Si-B system are potential high-temperature structural materials due to their good oxidation and creep resistance. Since they suffer from relatively high densities, the current study focuses on the influence of density-reducing Ti additions on creep and oxidation behavior at temperatures above 1273 K (1000 °C). Two alloys with compositions of Mo-12.5Si-8.5B-27.5Ti and Mo-9Si-8B-29Ti (in at. pct) were synthesized by arc melting and then homogenized by annealing in vacuum for 150 hours at 1873 K (1600 °C). Both alloys show similar creep behavior at stresses of 100 to 300 MPa and temperatures of 1473 K and 1573 K (1200 °C and 1300 °C), although they possess different intermetallic volume fractions. They exhibit superior creep resistance and lower density than a state-of-the-art Ni-base superalloy (single-crystalline CMSX-4) as well as other Mo-Si-B alloys. Solid solution strengthening due to Ti was confirmed by Vickers hardness measurements and is believed to be the reason for the significant increase in creep resistance compared to Mo-Si-B alloys without Ti, but with comparable microstructural length scales. The addition of Ti degrades oxidation resistance relative to a Mo-9Si-8B reference alloy due to the formation of a relatively porous duplex layer with titania matrix enabling easy inward diffusion of oxygen.     

Person re-identification in crowd

Person re-identification aims to recognize the same person viewed by disjoint cameras at different time instants and locations. In this paper, after an extensive review of state-of-the-art approaches, we propose a re-identification method that takes into account the appearance of people, the spatial location of cameras and potential paths a person can choose to follow. This choice is modeled with a set of areas of interest (landmarks) that constrain the propagation of people trajectories in non-observed regions between the field-of-view of cameras. We represent people with a selective patch around their upper body to work in crowded scenes when occlusions are frequent. We demonstrate the proposed method in a challenging scenario from London Gatwick airport and compare it to well-known person re-identification methods, highlighting their strengths and limitations. Finally, we show by Cumulative Matching Characteristic curve that the best performance results by modeling people movements in non-observed regions combined with appearance methods, achieving an average improvement of 6% when only appearance is used and 15% when only motion is used for the association of people across cameras.     

A generalized higher order neural network for aircraft recognition in a video docking system

In modern world of today where air traffic is continuously increasing and available space at the airports remains finite, there is a problem of safe docking of aircraft. The problem needs to be solved to ensure safe and smooth movement of aircraft, passengers and crew while making optimum utilization of available ground space. Without such systems having in place, accidents keep occurring due to human judgment errors. These accidents are causing loss of material costs and human injury. The importance of Video-based Docking Systems is continuously increasing due to the challenges of current and upcoming traffic demands of future. This paper evaluates two neural networks architectures for recognition of civil airliners in a Video docking system. The networks compared are feedforward neural network and probabilistic neural network. The results are compared by presenting data to neural networks while deforming the shape, adding noise and partly occluding the shape and presenting those angles for which network was not trained.     

Performance studies of phosphate‐doped polyaniline containing paint coating for corrosion protection of aluminium alloy

Polyaniline‐phosphate polymer was prepared chemically by oxidation polymerization of aniline in phosphoric acid medium using ammonium persulphate. The PANI‐phosphate polymer was characterized by FTIR, XRD, and SEM. The paints using PANI‐phosphate as pigment in acrylic and epoxy binder were prepared. The protective performance of the coating formed on aluminum alloy AA 2024 T3 was studied by electrochemical impedance spectroscopy in 0.5% NaCl solution. Both the coating systems have exhibited the coating resistance values above 1M Ω cm² even after 50‐days exposure in 0.5% NaCl solution. Besides the anticorrosion performance of PANI‐containing coating is comparable with that of chromate‐containing coating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Development of coating for temperature sensing

Fluorescence from a phosphor coating will indicate the temperature of the substrate to which it is attached, assuming thermal equilibrium is achieved. Synthesis of a phosphor pigment with europium as a doping element in RE₂O₃ (RE = Y) has been made. The synthesis is carried out by direct combustion method. The prepared Y₂O₃:Eu phosphor pigment was characterized by XRD, SEM and TEM. Using the synthesized phosphor pigment the paint has been formulated in silicone resin. The fluorescence was measured using fluorescence spectrometer and results are presented in this paper.