Multi-objective optimisation of pulsed Nd:YAG laser cutting process using integrated ANN–NSGAII model

The paper presents an integrated model of artificial neural networks (ANNs) and non-dominated sorting genetic algorithm (NSGAII) for prediction and optimization of quality characteristics during pulsed Nd:YAG laser cutting of aluminium alloy. A full factorial experiment has been conducted where cutting speed, pulse energy and pulse width are considered as controllable input parameters with surface roughness and material removal rate as output to generate the dataset for the model. In ANN–NSGAII model, back propagation ANN trained with Bayesian regularization algorithm is used for prediction and computation of fitness value during NSGAII optimization. NSGAII generates complete set of optimal solution with pareto-optimal front for outputs. Prediction accuracy of ANN module is indicated by around 1.5 % low mean absolute % error. Experimental validation of optimized output results less than 1 % error only. Characterization of the process parameters in pareto-optimal region has been explained in detail. Significance of controllable parameters of laser on outputs is also discussed.     

High‐Throughput Block Optical DNA Sequence Identification

Optical techniques for molecular diagnostics or DNA sequencing generally rely on small molecule fluorescent labels, which utilize light with a wavelength of several hundred nanometers for detection. Developing a label‐free optical DNA sequencing technique will require nanoscale focusing of light, a high‐throughput and multiplexed identification method, and a data compression technique to rapidly identify sequences and analyze genomic heterogeneity for big datasets. Such a method should identify characteristic molecular vibrations using optical spectroscopy, especially in the “fingerprinting region” from ≈400–1400 cm^?1. Here, surface‐enhanced Raman spectroscopy is used to demonstrate label‐free identification of DNA nucleobases with multiplexed 3D plasmonic nanofocusing. While nanometer‐scale mode volumes prevent identification of single nucleobases within a DNA sequence, the block optical technique can identify A, T, G, and C content in DNA k‐mers. The content of each nucleotide in a DNA block can be a unique and high‐throughput method for identifying sequences, genes, and other biomarkers as an alternative to single‐letter sequencing. Additionally, coupling two complementary vibrational spectroscopy techniques (infrared and Raman) can improve block characterization. These results pave the way for developing a novel, high‐throughput block optical sequencing method with lossy genomic data compression using k‐mer identification from multiplexed optical data acquisition.     

TelePatch: a middle layer for screening device fragmentation

Solutions in the domain of mobile computing face a typical problem of fragmentation due to permissible customization to android framework. Fragmentation is a problem at the device side where the expected behavior of an application is not exhibited identically over all other devices. Presently, cross-layer design is becoming essential aspect of the app development, targeted to deliver an energy-efficient and productive solution. Fragmentation is posing an enormous challenge for development community, and solutions are designed per case basis. There are solutions developed in the domain of graphics and Web access, but as far as the fragmentation with core framework is considered, the solution is still missing. In this paper, we are proposing an intermediate background app residing between the application and the core framework. The proposed app TelePatch generates a map between the intended calls with actually supported calls. The map so obtained can be used by the interested application to obtain the services from the core framework. In our case, we have deployed TelePatch with NeSen, used for capturing the network-state parameters using telephony API of the Android.     

Dielectric relaxation and viscoelastic behavior of polyurethane–titania composites: dielectric mixing models to explain experimental results

Polyurethane–titania nanocomposites with varying composition are prepared through two different mixing methods. The effect of titania on dielectric, mechanical, and thermal properties is investigated for different composites. A variety of electrical tests (like impedance and dielectric constant) are performed on the resultant composites and it was found that the dielectric constant of composites increased significantly, whereas impedance (|Z|) decreased with the increase in titania concentration. The effect of temperature on dielectric properties was also studied and it was found that the dielectric constant increased up to a certain temperature and beyond that it decreased. From mechanical testing, it is observed that the properties depend on both the composition and mixing methods. The glass transition temperature (T _g) of soft and hard segments along with vulcanization temperature (T _v) observed from the differential scanning calorimetry (DSC) are found to shift with the incorporation of titania into the PU matrix. The viscoelastic behavior of the nanocomposites was studied by dynamic mechanical analysis (DMA), and increase in storage modulus (E′) was achieved through addition of titania to the PU matrix, especially in the low strain region, whereas some decrease was observed in the higher strain region. Finally, different dielectric models were compared with the experimental data and the best match was achieved by the Lichtenecker model, especially at 1 kHz, which can be used as a predictive rule for different volume contents of titania filler in the PU matrix.     

Polyimide‐carbon nanotubes nanocomposites: electrical conduction behavior under cryogenic condition

This study is aimed to investigate the electrical conduction behavior of polyimide (PI)/multiwall carbon nanotubes (CNTs) nanocomposites in cryogenic environment (temperature from 10 to 300 K) prepared by in situ polymerization technique. The experimental results of direct current (DC) electrical conductivity have been fitted with different theoretical models to check their applicability and to understand the conduction behavior for the present nanocomposite system. The PI/CNT nanocomposites show low electrical percolation threshold. Negative temperature coefficient effect of resistivity is observed for all the composites under investigation. The analysis shows that Mott's variable range hopping (VRH) model is more applicable compared to Arrhenius and Kivelson models for the present composites over the entire range of measurement temperature. The electronic transport behavior in each composite at temperature above 70 K can be ascribed to thermally activated tunneling of charge carriers through insulating barriers between CNTs; however, the electronic transport behavior at temperature below 70 K can be attributed to three dimensional VRH of charge carriers through the networks of CNTs in the polymer composite. The current–voltage characteristics of the composite show non‐ohmic behavior for temperature below 60 K and become ohmic in nature as temperature rises to 300 K. POLYM. ENG. SCI., 57:291–298, 2017. © 2016 Society of Plastics Engineers     

Deep learning for vision‐based fall detection system: Enhanced optical dynamic flow

Accurate fall detection for the assistance of older people is crucial to reduce incidents of deaths or injuries due to falls. Meanwhile, vision‐based fall detection system has shown some significant results to detect falls. Still, numerous challenges need to be resolved. The impact of deep learning has changed the landscape of the vision‐based system, such as action recognition. The deep learning technique has not been successfully implemented in vision‐based fall detection system due to the requirement of a large amount of computation power and requirement of a large amount of sample training data. This research aims to propose a vision‐based fall detection system that improves the accuracy of fall detection in some complex environments such as the change of light condition in the room. Also, this research aims to increase the performance of the pre‐processing of video images. The proposed system consists of Enhanced Dynamic Optical Flow technique that encodes the temporal data of optical flow videos by the method of rank pooling, which thereby improves the processing time of fall detection and improves the classification accuracy in dynamic lighting condition. The experimental results showed that the classification accuracy of the fall detection improved by around 3% and the processing time by 40–50 ms. The proposed system concentrates on decreasing the processing time of fall detection and improving the classification accuracy. Meanwhile, it provides a mechanism for summarizing a video into a single image by using dynamic optical flow technique, which helps to increase the performance of image preprocessing steps.     

Electron-beam-initiated grafting of triallyl cyanurate onto polyethylene: Structure and properties

Electron-beam (EB)-initiated grafting of triallyl cyanurate (TAC) onto polyethylene (PE) has been carried out over a range of radiation dose (2–20 Mrad) and concentrations of TAC (0.5–3 parts by weight). The grafting level, as determined from IR spectroscopy, is maximum at a 10 Mrad radiation does using 1 part TAC. With increasing TAC level at a 15 Mrad dose, the grafting level is higher only after 1.5 parts TAC. The gel content increases with radiation dose in the initial stages. X-ray studies indicate two peaks at 10.6–10.8° and 11.7–11.9° and the corresponding interplaner distances of 4.15 and 3.80 Å. With increase in radiation dose or TAC level, the crystallinity decreases in the initial stage and then increases. It shows a decreasing trend again at higher radiation dose. The interplanar distance or the interchain distance of the modified polymer does not change. However, the crystallite size increases initially and then decreases. The tensile properties are relatively insensitive to the variation of radiation dose because of the interplay of various factors. The dielectric loss, tan δ, shows a maximum at a 10 Mrad dose and minimum at 5 and 15 Mrad due to changes of polarity and the carrier mobility. © 1994 John Wiley & Sons, Inc.     

Effect of ambient‐temperature and high‐temperature electron‐beam radiation on the structural,thermal, mechanical,and dynamic mechanical properties of injection‐molded polyamide‐6,6

Electron‐beam irradiation of injection‐molded specimens of polyiminohexamethyleneiminoadipoyl (better known as polyamide‐6,6) was carried out in air at ambient temperature (303 K) and a high temperature (393 K). Most of the irradiated specimens were tensile dumbbells, although a few were cylinders for compressive stress relaxation testing. A few representative samples were dipped in triallyl cyanurate (TAC) solution before ambient‐temperature irradiation. The gel content of the specimens increased with radiation dose and the temperature of irradiation. Moreover, the TAC‐treated specimens showed an increase in gel content over the neat specimens irradiated at the same dose levels. Wide‐angle X‐ray scattering and differential scanning calorimetry studies revealed that the crystallinity decreased with increasing radiation dose. Irradiation at the high temperature and treatment with TAC further decreased the crystallinity compared to irradiation at ambient temperature. As determined from compressive stress relaxation and mechanical and dynamic mechanical properties, the optimized radiation dose for ambient‐temperature radiation was 200 kGy. The gels had a stiffening effect, and the rate of relaxation decreased significantly. The water‐uptake characteristics of the tensile specimens were investigated; this revealed a decrease in the water absorption tendency with increasing gel content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1633–1644, 2006     

Effect of processing parameters, applied pressure and temperature on the electrical resistivity of rubber-based conductive composites

Carbon black- and short carbon fibre (SCF)-filled conductive composites were prepared from ethylene vinyl acetate (EVA), ethylene propylene diene (EPDM) rubber and their 50:50 blend. The electrical resistivity of carbon black- and SCF-filled composites were measured under different conditions. The electrical conductivity of filled polymer composites is due to the formation of a continuous conductive network in the polymer matrix. These conductive networks involve specific arrangement of conductive elements so that the electrical paths are formed for free movement of electrons. It was found that electrical conductivity of filled conductive composites depends on different processing parameters like mixing time, rotor speed, mixing temperature, vulcanization time and pressure and service conditions like applied pressure and temperature. The results of different experiments have been discussed in light of break down and formation of the continuous conductive network.     

Viruses in groundwater beneath sewage irrigated cropland

The occurrence of enteric viruses in groundwater and soil was examined beneath three different sites where slow rate sewage irrigation of cropland is practiced. At all sites, the sewage was secondarily treated (aeration) before land application. Enteric viruses were isolated from wells beneath all sites. The lowest frequency of isolation was from wells beneath the one site practicing chlorination before application by spray irrigation. Viruses were detected in wells as deep as 27.5 m.