Experimental and numerical characterization of shape memory polymer and metal laminates

The interface strength of a Shape Memory Polymer – Stainless Steel (SMP-SS) laminate system has been studied under a wide range of test conditions. The adhesive strength of the laminates has been explored using the peel test at room temperature as well as the glass transition temperature of the SMP. The analysis was also repeated at varying speeds and SMP thickness in order to quantify the effect of strain rate and adherend thickness on the bond strength of the laminate.

The experimental tests have been validated using finite element analysis of the SMP – SS laminate system. The finite element study further explores the role of polymer stresses and strains in the polymer film and adhesive layer in inducing delamination and wrinkling.

Significant decrease in strains in the adherend are observed on increasing its thickness. The adhesive strength of the laminate system is found to decrease at higher temperatures. Also the adherend is observed to wrinkle at longitudiunal strains nearing 35%.     

Protocol design and resource allocation for power optimization using spectrum sharing for 5G networks

Telecommunication Systems - In this paper, we propose a spectrum sharing protocol wherein the sharing is performed in a situation without introducing a secondary transmitter in assisting the...     

Micro‐Doppler classification of human movements using spectrogram spatial features and support vector machine

Accurate distinction of dynamic moving objects especially in the context of security surveillance attracts great attention of researchers and practitioners. In the same context, present study proposes an advancement in feature extraction method from the micro‐Doppler spectrogram with the application of spatial statistics for moving human subject classification which minimizes the spectrogram analysis. A novel approach of spatial feature extraction from whole image spectrogram, followed by support vector machine (SVM) classifiers algorithm for multiclass classification, has been proposed in the present study. The proposed method has been tested for prediction accuracy and validated by applying on a very close and important five distinct human activities (which usually arise at any security observation site) as reported in the available literature. The results obtained adopting the proposed approach exhibit high accuracy for multiclass classification; yielding cross‐validation accuracy of 96.7% while actual predication of testing data provides the accuracy of 93.33%. For the prediction of accurate data classes, the post‐processing of the spectrogram prior to feature definition has also been performed using spatial based methods to enhance micro‐Doppler signatures.     

The socio-technical barriers to Solar Home Systems (SHS) in Papua New Guinea: “Choosing pigs,prostitutes, and poker chips over panels”

This study explores the socio-technical barriers to Solar Home Systems (SHS) in Papua New Guinea. The authors collected primary data through semi-structured research interviews conducted over the course of February 2010–April 2010. Respondents included government officials, financiers, planners, commercial distributors and companies, teachers and rural villagers in addition to members of civil society, academics, consultants, and trainers. These interviews were supplemented with site visits to Port Moresby, Goroka, and Madang, and field research in the villages of Akameku, Asaroka, Lufa, Kundiawa, Okifa, Simbu, and Talidig. The study draws from these interviews and visits to discuss four types of barriers. Technical barriers relate to substandard equipment and logistical problems. Economic barriers include high rates of poverty, misconceptions about the role of currency, and lack of financing. Political barriers include poor institutional capacity and a government commitment to fossil-fueled grid electrification. Social barriers encompass unrealistic expectations about what SHS can provide along with jealousy, theft, vandalism, and unfamiliarity with solar technology.     

Optimization of long-term storage stability of Jatropha curcas biodiesel using antioxidants by means of response surface methodology

The present paper reports the results of the study of the effect of metal contaminants on the storage stability of Jatropha curcas biodiesel (JCB) with and without antioxidants. Taking 1,2,3 -Trihydroxybenzene/Pyrogallol (PY) as the most effective antioxidant based on the earlier work of the authors, JCB was mixed with different transition metals – Fe, Ni, Mn, Co and Cu in different concentrations. Induction period (IP) was measured using Rancimat method (EN 14112) as the stability parameter. Based on results, several correlations were developed for assessing the storage stability in terms of IP as a function of antioxidant, metal concentration and storage time. For the purpose of design of experiment, response surface methodology (RSM) has been used. From the experiments it is found that if metal concentration is 0 then, 200 g m⁻³ of PY is sufficient to make biodiesel stable for 6 months. If metal (Fe) concentration is 2 g m⁻³ or more, then 800 g m⁻³ PY is sufficient to make biodiesel stable for 5.5 months. The value of storage time for Ni, Mn, Co and Cu contaminated JCB is found as 3.62, 3.24, 2.76 and 2.07 months respectively if metal and antioxidants concentration is same in all the cases.The models developed by RSM shall be highly useful for predicting the optimum antioxidant concentration to achieve maximum storage stability of JCB as well as biodiesel from other resources under the conditions set for 3 factors (antioxidant concentration, metal concentration and time).     

CSRR and open-stub based circular polarized and double band eight-ports MIMO antenna for 5G and ISM band applications

Microsystem Technologies - In this paper, a circular-polarized and double band eight-element MIMO antenna is designed. The presented antenna is based on the complementary split ring resonator...     

Photovoltaic performance of hybrid ITO/PEDOT: PSS/n-SnS/Al solar cell structure

The present paper discusses the performance of ITO/PEDOT:PSS/n-SnS/Al structured solar cells fabricated by thermal evaporation. The performance characterizing parameters such as the open circuit voltage, short circuit current density, series resistance, parallel resistance, ideality factor and the overall efficiency were found to be dependent on the SnS grain size in the nano-meter regime and incident light intensity. The experimental work directly reconfirms the theoretical results and ideas raised in the literature by early researchers.     

Polymer induced turbulent drag reduction using pressure and gravity-driven methods

Drag reduction using polymer additives has been industrially important for enhancing the flow rates and hence the power consumption. In this study, various polymers like PEG, PAM, HPMC were employed with solvents like water and lubricating oil for drag reduction using gravity and pressure driven methods. The optimum set of parameters for maximum drag reduction—polymer concentration, nature of polymer, polymer combinations, exit pipe diameter, solvent-polymer combinations, experimental methodology—were obtained and then the results validated with well known concepts like the Toms effect and Virk's maximum drag reduction asymptote.