Design of Novel Dual Input DC–DC Converter for Energy Harvesting System in IoT Sensor Nodes

A new DC–DC converter capable of working with more than one source for harvesting energy from clean energy sources is proposed. Key features of this proposed converter are single inductor and reduced total number of components. In addition the converter has reduced stresses and power losses. Dual input and output modes, with its operation and steady-state analysis are discussed. Comparative study of the topologies given in literature with a proposed topology for parameters considered like the number of components and voltage gain is presented. Compatibility of the proposed converter is proved with reduced losses using loss distribution analysis of the converter and it is more reliable for energy system in telecom applications, which is validated using reliability analysis, is also highlighted. Finally, to substantiate the working of the non isolated DC–DC converter considered the test results are presented.

     

Mathematical Description of Experimentally Determined Charge Distributions of a Unipolar Diffusion Charger

The charge distributions of an improved opposed flow unipolar diffusion charger were measured using a tandem differential mobility analyzer (DMA) set up in a size range of approximately 20–400 nm. The charger is intended to be used in a portable aerosol sizer to measure particle size distributions. The determined charge distributions were represented by lognormal distributions, and a set of equations and coefficients was developed to calculate the charge distributions. These equations can be easily implemented in software for size distribution measurements. The agreement between the mathematically derived and measured charge distributions is very good, with regression coefficients R ² > 0.96. The investigations showed that approximately 55% of 20-nm particles remain uncharged, while up to 25 elementary charges need to be considered for multiple charge correction of 400-nm particles. Comparison with the Fuchs theory delivered satisfying agreement with the measured average charge levels, but charge distributions cannot be described by the Fuchs theory, likely caused by the charger geometry.

Copyright 2012 American Association for Aerosol Research     

Parametric study of aluminium alloy fouling in marine environment using RSM technique

ABSTRACT

Fouling is known to be a prominent industrial problem which is greatly affected by parameters like temperature, time and flowrate. The aim of this work was to simulate the fouling process in AA 6061 by developing a model through Minitab 16 and evaluate the models. Box Behnken design of Response surface methodology was applied for modelling and optimization of fouling propensity in artificial sea water. A response surface model was obtained and Analysis of Variance was performed to test the significance of the model. Fouling propensity was found in terms of weight gain. An experimental rig consisting of a recirculating loop mimicking the industrial conditions of fouling was used in the study. SEM analysis shows uneven deposits on the metal surface. Sharp, irregular deposits pressed deep into the metal was observed. The finding of this work would enable us to evaluate the individual and interactive effects of the parameters.     

Histomorphometric and histologic evaluation of titanium–zirconium (<Emphasis Type="Italic">a</Emphasis>TiZr) implants with anodized surfaces

The choice of implant surface has a significant influence on osseointegration. Modification of TiZr surface by anodization is reported to have the potential to modulate the osteoblast cell behaviour favouring more rapid bone formation. The aim of this study is to investigate the effect of anodizing the surface of TiZr discs with respect to osseointegration after four weeks implantation in sheep femurs. Titanium (Ti) and TiZr discs were anodized in an electrolyte containing dl-α-glycerophosphate and calcium acetate at 300 V. The surface characteristics were analyzed by scanning electron microscopy, electron dispersive spectroscopy, atomic force microscopy and goniometry. Forty implant discs with thickness of 1.5 and 10 mm diameter (10 of each-titanium, titanium–zirconium, anodized titanium and anodized titanium–zirconium) were placed in the femoral condyles of 10 sheep. Histomorphometric and histologic analysis were performed 4 weeks after implantation. The anodized implants displayed hydrophilic, porous, nano-to-micrometer scale roughened surfaces. Energy dispersive spectroscopy analysis revealed calcium and phosphorous incorporation into the surface of both titanium and titanium–zirconium after anodization. Histologically there was new bone apposition on all implanted discs, slightly more pronounced on anodised discs. The percentage bone-to-implant contact measurements of anodized implants were higher than machined/unmodified implants but there was no significant difference between the two groups with anodized surfaces (P > 0.05, n = 10). The present histomorphometric and histological findings confirm that surface modification of titanium–zirconium by anodization is similar to anodised titanium enhances early osseointegration compared to machined implant surfaces.     

Cost Effective Decentralized Key Management Framework for IoT

Security is a primary concern in communication for reliable transfer of information between the authenticated members, which becomes more complex in a network of Internet of Things (IoT). To provide security for group communication a key management scheme incorporating Bilinear pairing technique with Multicast and Unicast key management protocol (BMU-IOT) for decentralized networks has been proposed. The first part of the proposed work is to divide the network into clusters where sensors are connected to and is administered by cluster head. Each sensor securely shares its secret keys with the cluster head using unicast. Based on these decryption keys, the cluster head generates a common encryption key using bilinear pairing. Any sensor in the subgroup can decrypt the message, which is encrypted by the common encryption key. The remaining part focuses to reduce communication, computation and storage costs of the proposed framework and the resilience against various attacks. The implementation is carried out and results are compared with the existing schemes that have given considerably better results. Thus, the lightweight devices of IoT can provide efficiency and security by reducing their overhead in terms of complexity.     

Recognizing Materials Using Perceptually Inspired Features

Our world consists not only of objects and scenes but also of materials of various kinds. Being able to recognize the materials that surround us (e.g., plastic, glass, concrete) is important for humans as well as for computer vision systems. Unfortunately, materials have received little attention in the visual recognition literature, and very few computer vision systems have been designed specifically to recognize materials. In this paper, we present a system for recognizing material categories from single images. We propose a set of low and mid-level image features that are based on studies of human material recognition, and we combine these features using an SVM classifier. Our system outperforms a state-of-the-art system (Varma and Zisserman, TPAMI 31(11):2032–2047, 2009) on a challenging database of real-world material categories (Sharan et al., J Vis 9(8):784–784a, 2009). When the performance of our system is compared directly to that of human observers, humans outperform our system quite easily. However, when we account for the local nature of our image features and the surface properties they measure (e.g., color, texture, local shape), our system rivals human performance. We suggest that future progress in material recognition will come from: (1) a deeper understanding of the role of non-local surface properties (e.g., extended highlights, object identity); and (2) efforts to model such non-local surface properties in images.     

Wimax (IEEE 802.16 m) system based on space time block code and discrete multiwavelet transform and implementation in FPGA

MIMO (Multiple Input Multiple Output) scheme uses transmit diversity technique which results in high throughput with increased channel capacity. The complexity of MIMO system increases the area and power requirements of the system. The proposed work is to achieve good spectral efficiency and reduction of interference by introducing multiwavelet with MIMO technology. The improvements directly results in reduction of BER (Bit Error Rate) for a given SNR (Signal to Noise Ratio). Implementation of the proposed scheme in FPGA (Field Programmable Gate Array)—virtex5 (xcvlx30t-1f665) shows a considerable improvement in speed and area when compared with the existing methods.     

Biodesulfurization of dibenzothiophene using recombinant Pseudomonas strain

BACKGROUND: The sulfur content in crude oil available from various sources ranges from 0.03 to values as high as 8.0 wt%. These high quantities of sulfur must be removed before the crude oil is processed because combustion of this oil would result in severe environmental pollution, such as acid rain. Due to high utility and operating costs, the conventional hydrodesulfurization process (HDS) is considered to be uneconomic. The biotechnological option, biodesulfurization (BDS) seems an attractive low cost, environmentally benign technology. RESULTS: This paper reports the development of a recombinant strain of bacteria designed by introducing desulfurizing, dsz genes containing plasmid pSAD 225‐32, which was isolated from Rhodococcus erythropolis IGTS8 into a gram negative solvent‐tolerant bacterium, Pseudomonas putida (MTCC 1194). This recombinant bacterium can desulfurize the dibenzothiophene (DBT) in the sulfur selective 4S‐pathway. It has been observed that for the same concentration of DBT, the recombinant strain's growth rate is greater than that of the parent strain. Increasing the concentration of DBT resulted in an increase of lag phase as well as decreased growth rate, which shows that the bacteria is following substrate inhibition type kinetics. This genetically modified bacterium can desulfurize 73.1% of 1.2 mmol L^?1 DBT (dissolved in ethanol) in 67 h of cultivation time using growing cells. CONCLUSIONS: It is concluded that further research in this area of biodesulfurization using genetically modified organisms may remove the bottlenecks presently in the way of commercialization of the BDS process. Copyright © 2007 Society of Chemical Industry     

Emotional and motivational changes after bilateral lesions of the globus pallidus.

This study investigated motivational changes in a 44 year-old man (PJ) who developed considerable reduction in spontaneous activity and speech, flat affect, social withdrawal, loss of interest, inability to "feel," and lack of concern regarding his medical condition after bilateral, focal, anoxic lesions of the globus pallidus. PJ and 30 male controls performed a task designed to parse hedonic evaluation, or liking, from incentive motivation, or wanting. Affective stimuli were presented on a computer screen and subjects controlled viewing time by pressing keys. PJ's liking and wanting of unpleasant stimuli was similar to that of controls. In response to pleasant stimuli, PJ showed normal ratings of wanting and hedonic appreciation, but significantly reduced viewing time or made no responses. Active withdrawal from liked stimuli could constitute the basic mechanism underlying poor motivation and social withdrawal associated with globus pallidus damage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)