A Novel Framework for Human Activity Recognition with Time Labelled Real Time Sensor Data

Human activity recognition is an effective approach for identifying the characteristics of historical data. In the past decades, different shallow classifiers and handcrafted features were used to identify the activities from the sensor data. These approaches are configured for offline processing and are not suitable for sequential data. This article proposes an adaptive framework for human activity recognition using a deep learning mechanism. This deep learning approach forms the deep belief network (DBN), which contains a visible layer and hidden layers. The processing of raw sensor data is performed by these layers and the activity is identified at the top most layers. The DBN is tested using the real time environment with the help of mobile devices that contain an accelerometer, a magnetometer, and a gyroscope. The results are analyzed with the metrics of precision, recall, and the F1-score. The results proved that the proposed method has a higher F1_score when compared to the existing approach.     

Performance comparison of AlGaAs,GaAs and InGaP tunnel junctions for concentrated multijunction solar cells

Four tunnel junction (TJ) designs for multijunction (MJ) solar cells under high concentration are studied to determine the peak tunnelling current and resistance change as a function of the doping concentration. These four TJ designs are: AlGaAs/AlGaAs, GaAs/GaAs, AlGaAs/InGaP and AlGaAs/GaAs. Time‐dependent and time‐average methods are used to experimentally characterize the entire current–voltage profile of TJ mesa structures. Experimentally calibrated numerical models are used to determine the minimum doping concentration required for each TJ design to operate within a MJ solar cell up to 2000‐suns concentration. The AlGaAs/GaAs TJ design is found to require the least doping concentration to reach a resistance of <10⁻⁴ Ω cm² followed by the GaAs/GaAs TJ and finally the AlGaAs/AlGaAs TJ. The AlGaAs/InGaP TJ is only able to obtain resistances of ≥5 × 10⁻⁴ Ω cm² within the range of doping concentrations studied. Copyright © 2010 John Wiley & Sons, Ltd.     

Graphene–Mesoporous Si Nanocomposite as a Compliant Substrate for Heteroepitaxy

The ultimate performance of a solid state device is limited by the restricted number of crystalline substrates that are available for epitaxial growth. As a result, only a small fraction of semiconductors are usable. This study describes a novel concept for a tunable compliant substrate for epitaxy, based on a graphene–porous silicon nanocomposite, which extends the range of available lattice constants for epitaxial semiconductor alloys. The presence of graphene and its effect on the strain of the porous layer lattice parameter are discussed in detail and new remarkable properties are demonstrated. These include thermal stability up to 900 °C, lattice tuning up to 0.9 % mismatch, and compliance under stress for virtual substrate thicknesses of several micrometers. A theoretical model is proposed to define the compliant substrate design rules. These advances lay the foundation for the fabrication of a compliant substrate that could unlock the lattice constant restrictions for defect‐free new epitaxial semiconductor alloys and devices.     

Comprehensive design methodology for control and data planes in wavelength-routed optical networks

We propose a comprehensive design methodology for control and data planes of wavelength-routed optical networks (WRONs) employing mixed-line-rate (MLR) transmission for cost-effective resource provisioning. The proposed approach attempts to minimize the maximum lightpath capacity demand in Gbps (representing the measure of lightpath congestion) in network for a given traffic matrix by using a mix of a heuristic scheme and linear programming (LP). In the first step of the proposed three-step design, some lightpaths are set up on a set of judiciously selected fiber links (with point-to-point lightpaths between neighboring nodes), on a specific wavelength throughout the network, and an appropriate fraction of the same set of lightpaths is utilized for carrying control information, forming therefore the control plane (CP) of the WRON. The remaining bandwidth of these lightpaths is utilized to carry the data traffic along with all other designed lightpaths of the WRON using appropriate algorithm, forming the overall data plane (DP) of the WRON. In the second step, traffic routing is carried out through LP to minimize lightpath congestion in the network. In the third step, we utilize the results of LP to assign rates to lightpaths, such that the cost (considering only the transceiver cost) of the network is minimized. This design leads to congestion-aware MLR network with due consideration to cost-effectiveness without compromising the network restoration response against link failures. We carry out simulation studies employing possible CPs using both symmetric (CP topology being same as the physical topology) as well as asymmetric (using fewer fiber links than the symmetric case) topology. The results of our simulations indicate that the proposed design of CP with symmetric/asymmetric topology and in-band transmission with sub-lightpath capacity can bring down network congestion and cost with respect to symmetric out-of-band transmission (using fully reserved lightpaths for CP), without any perceptible sacrifice in respect of the network restoration time. Failure can occur either in CP or DP, or in both the planes. We investigate the effect of design of CP with symmetric/asymmetric topology on network restoration time for single- and double-link failures. We further present DP design methodology with hybrid restoration scheme, i.e., combination of dedicated (1:1) path protection and path restoration. We analyze the effect of symmetric CP topology and degree of protection on the congestion of the network. Some lightpaths, that support more traffic, are protected against failures, while the others are left for path restoration in the event of failures. As more lightpaths are protected, the congestion and power consumption of network increase. We provide an analysis of the factors that come into play while altering the degree of protection and observe how the choice for the degree of protection in DP can be arrived at using an appropriate design methodology.     

Optimization and evaluation of microwave-assisted synthesis of magnetite as a carrier for targeted drug delivery system

ABSTRACT

The present research work is a novel cost-effective method for synthesis of magnetite. Magnetite is a carrier which is used in the targeted drug delivery system. The conventional methods of preparation of magnetite take around 6–7 h for the completion of reaction; moreover, the particle size of magnetite which we get by the conventional methods is above 5 µm, so the present work aims at preparing magnetite with microwave assistance which has found to reduce reaction time with particle size obtained below 5 µm. The aim of this study was to optimize magnetite synthesis using 2³ factorial design by Design-Expert software. Magnetites were synthesized using oxidation of ferrous sulfate. In the next step, the effects of different variables on particle size are studied, including the stirring speed, microwave power (W), and stirring time. Based on the type and the variables studied, eight formulations were designed using factorial design method, and were then prepared, and their particle size was determined. Finally, selected magnetite syntheses were evaluated from the viewpoints of scanning electron microscopy (SEM) and x-ray diffraction (XRD). Results revealed that magnetite obtained from the solutions generated Design-Expert software could be selected as the best and optimized formulations due to their lowest particle size.     

Second Harmonic Generation Investigation of Symmetry Breaking and Flexoelectricity Induced by Nanoindentations in SrTiO3

Strain gradients induced by nanoindentations in bulk undoped strontium titanate (SrTiO₃) are investigated. After indenting a 850 nm deep pattern on the SrTiO₃ surface with a 8 GPa hardness and an 83 GPa indentation modulus by a Berkovich tip, the resulting deformation patterns are imaged by Raman spectroscopy and by second harmonic generation microscopy. Cross‐shaped compressively stressed regions along the cubic SrTiO₃ primary slip planes are observed. These zones relax toward the unstrained bulk material through localized strain gradients on a length scale of several microns. Second harmonic tomography reveals the reduction of the crystal's centrosymmetry in the vicinity of the crosslike features due to a strain gradient. These results indicate the appearance of flexoelectricity following the nanoindentation process due to the creation of an inhomogeneous strain.     

Size-dependent magnetic and dielectric properties of Tb-doped BiFeO3 nanoparticles

Pure and Tb-doped BiFeO₃ nanoparticles have been prepared by sol–gel method. The nanoparticles of different size have been obtained by the calcination of synthesized nanoparticles at different temperatures. The effects of Tb doping and size of nanoparticles on the crystal structure, magnetic and electrical properties have been studied. The partial substitution of Tb ions results in a change from rhombohedral (x = 0) to orthorhombic (x = 0.15) structure. The average crystallite size varies from 14 to 40 nm. The synthesized nanoparticles possess ferromagnetic behavior. The saturation magnetization is high for the Tb-doped BiFeO₃ nanoparticles calcined at 450 °C, and it decrease with the increase of size. The dielectric constant and loss improve with Tb doping and size. The relaxation behavior of dielectric loss is of Debye type. The dielectric loss peaks shift to the lower frequencies with increase in the size of Tb-doped BiFeO₃ nanoparticles.     

Variations in normal color vision. III. Unique hues in Indian and United States observers

Basic color categories are thought to share a common pattern across linguistic groups, yet the focal colors defining those categories can vary substantially within any single group. We asked whether focal colors can also differ systematically across different groups of individuals living in potentially different color environments, by measuring focal and unique hues for observers in India and the United States. Differences between groups were generally small relative to the within-group variations, consistent with a strong common basis for color naming across diverse contexts. However, for most hues the average settings differed significantly across subpopulations. These differences persisted across testing conditions and thus probably reflect longer-term contextual influences on color appearance judgments. They suggest that while color categories may be qualitatively similar, precisely how the hue spectrum is parsed may differ quantitatively across different populations of observers. Both the between-group and the within-group differences are inconsistent with the differences predicted by common peripheral sources of variation in color vision (e.g., in lens or macular pigment) and may reflect an influence of environmental or cultural differences in focal color choices.