Fabrication of suspended carbon microstructures by e-beam writer and pyrolysis

A fabrication process has been developed to create suspended carbon microelectromechanical system (C-MEMS) structures. SU-8, a negative photoresist, was used as the starting material and was converted to the desired carbon microstructures using pyrolysis in an inert atmosphere. Suspended carbon-micro and nano electromechanical system (C-MEMS/NEMS) structures with feature sizes down to 500 nm were fabricated by ultra violet/electron beam (EB) lithography and pyrolysis. The problem of charging of the non-conductive SU-8 surface was solved by partially masking a thin metal layer to prevent the repulsion of negative charged electrons before EB writing. Complex suspended C-MEMS structures, such as bridges and networks have been formed. This fabrication method can accurately and reproducibly produce various suspended C-MEMS structures which have applications in microelectronics and biosensing.     

Development of noncontact end effector for handling of bakery products

The application of automation for handling of nonrigid or semirigid products and air permeable materials is limited due to lack of suitable end effectors. The majority of robotic manipulators and end effectors are not easily applicable because of lack of contact rigidity with nonrigid or semirigid products due to their unpredictable and unstable behaviour and with materials which are sensitive to deformation, especially bakery products (baked and unbaked) in the biscuits industry (Erzincanli and Sharp, Food Control 8:185–190, 1997). Also, during the handling process, the risk of contamination is high due to direct contact with food products. Hence, the need for noncontact robotic end effectors is strongly felt. In this paper a noncontact type end effector having a rectangular cross-section designed for handling bakery products is discussed for use in the biscuits manufacturing industry. These end effectors operate on the principle of generating vacuum, which lifts the material without any mechanical contacts. The present work explores the possibility of using radial flow nozzles in the biscuits industry. The basic working principle is presented, followed by experimental results. An automatic noncontact end effector system may be found quite useful for the food handling industry.     

India's emissions in a climate constrained world

Scientific studies have repeatedly shown the need to prevent the increase in global emissions so that the planet's average temperature does not exceed 2 °C over pre-industrial levels. While the divisions between Annex 1 and non-Annex nations continue to prevent the realization of a comprehensive global climate treaty, all members of the G-20 (incidentally also major emitters) have agreed to prevent the rise in global temperatures above 2 °C. This requires that nations consider budgeting their carbon emissions. India presents a unique case study to examine how a major emitter facing a desperate need to increase energy consumption will meet this challenge. The Greenhouse Development Rights (GDR) framework, perhaps considered the most favorable with respect to the responsibility and capacity of India to reduce emissions, was used to explore India's emissions trajectory. India's emissions have been pegged to the pathway required to meet the 2 °C target by non-Annex countries. The results have been compared to the expected emissions from 11 energy fuel mix scenarios up to the year 2031 forecasted by the Planning Commission of India. Results reveal that none of the 11 energy scenarios would help India meet its emissions target if it were to follow the 2 °C pathway. A thought experiment is followed to explore how India may meet this target. This includes a sensitivity analysis targeting coal consumption, the biggest contributor to India's emissions.     

Design of efficient lightweight strategies to combat DoS attack in delay tolerant network routing

Delay tolerant networks (DTNs) are characterized by delay and intermittent connectivity. Satisfactory network functioning in a DTN relies heavily on co-ordination among participating nodes. However, in practice, such co-ordination cannot be taken for granted due to possible misbehaviour by relay nodes. Routing in a DTN is, therefore, vulnerable to various attacks, which adversely affect network performance. Several strategies have been proposed in the literature to alleviate such vulnerabilities—they vary widely in terms of throughput, detection time, overhead etc. One key challenge is to arrive at a tradeoff between detection time and overhead. We observe that the existing table-based reactive strategies to combat Denial-of-service (DoS) attacks in DTN suffer from two major drawbacks: high overhead and slow detection. In this paper, we propose three secure, light-weight and time-efficient routing algorithms for detecting DoS attacks (Blackhole and Grey-hole attacks) in the Spray & Focus routing protocol. The proposed algorithms are based on use of a small fraction of privileged (trusted) nodes. The first strategy, called TN, outperforms the existing table-based strategy with 20–30 % lesser detection time, 20–25 % higher malicious node detection and negligible overhead. The other two strategies, CTN_MI and CTN_RF explore the novel idea that trusted nodes are able to utilize each others’ information/experience using their long range connectivity as and when available. Simulations performed using an enhanced ONE simulator reveals that investing in enabling connectivity among trusted nodes (as in CTN_RF) can have significant performance benefits.     

Synthesis of diethyl carbonate from ethanol through different routes: A thermodynamic and comparative analysis

In this study, thermodynamic analysis of various possible synthesis routes of diethyl carbonates (DEC), a benign organic carbonate, was carried out and a comparative analysis was performed. Chemical equilibrium constants at standard conditions were calculated using Gibbs free energy of the system. The Benson group contribution method was used to estimate standard heat of formation and standard entropy change of some raw materials/components like dimethyl carbonate. Variation of heat capacity (C_p) with temperature was estimated for different components from the Rozicka‐Domalski model. Variation of chemical equilibrium constants with temperature and pressure was studied for various routes. Synthesis of DEC from ethylene carbonate (EC) was also found to be better considering equilibrium constants at room temperature. The CO₂ route was found to be the most unfavourable route for DEC synthesis due to stability of CO₂ molecules. Moreover, DEC synthesis through the urea route was found to be best at high temperatures since the equilibrium constants were found to increase exponentially. Experiments were conducted for DEC synthesis using the EC route at two temperatures. Activity coefficients were calculated using the UNIFAC model. Experimentally and theoretically determined chemical equilibrium constant values were found to be similar. PRO/II was also used to minimize Gibbs free energy of the system and estimate the equilibrium constants and the results were comparable with those obtained by the equilibrium constant method and the trend was found to be the same for both the methods.     

CFD simulation of a chemical-looping fuel reactor utilizing solid fuel

A computational fluid dynamic (CFD) study has been carried out for the fuel reactor for a new type of combustion technology called chemical-looping combustion (CLC). CLC involves combustion of fuels by heterogeneous chemical reactions with an oxygen carrier, usually a granular metal oxide, exchanged between two reactors. There have been extensive experimental studies on CLC, however CFD simulations of this concept are quite limited. In the present paper we have developed a CFD model for the fuel reactor of a chemical-looping combustor described in the literature, which utilized a Fe-based carrier (ilmenite) and coal. An Eulerian multiphase continuum model was used to describe both the gas and solid phases, with detailed sub-models to account for fluid–particle and particle–particle interaction forces. Global reaction models of fuel and carrier chemistry were utilized. The transient results obtained from the simulations were compared with detailed experimental time-varying outlet species concentrations (Leion et al., 2008) and provided a reasonable match with the reported experimental data.     

Determinants of Mobile Wallet Intentions to Use: The Mental Cost Perspective

Mobile wallet has become the predominant form of electronic commerce in many countries, and India is no exception. It is imperative to understand the behavior of users of mobile wallets as it can help service providers to attract new users and retain their existing ones. For predicting intentions to use from a mental cost perspective, this empirical study focuses on evaluating different competing models using relevant, vital constructs rooted in theories of Diffusion of Innovation, Planned Behavior, and Technology Acceptance Model and Trust. Results point to the supremacy of the Perceived Behavioral Control construct over other constructs in predicting the intentions, to use mobile wallets. Among the competing models, the best predictive model explained 50.81% of the changes in intentions to use.     

SPICE source code implementation of aDC model for the non pinchoff depletion mode MOSFET

The implementation of the Lin model for the non pinchoff depletion mode MOSFETs directly into the source code of the SPICE 2G.5 circuit simulation program is described. The computational advantages of our implementation over Lin's subcircuit approach are pointed out, and, more significantly, certain previously undiscovered limitations of both methods are discussed. The encoding of the model into SPICE is described in sufficient detail so as to be duplicable by other interested researchers. Our results compare favorably to experiment and to the more comprehensive El-Mansy model. Finally, a new method of parameter extraction is described for the El-Mansy model, which makes it possible to derive the parameters of the Lin and El-Mansy models simultaneously.     

Non-destructive Evaluation and Development of a New Wire Rope Tester Using Parallely Magnetized NdFeB Magnet Segments

A new wire rope tester based on principle of magnetic flux leakage is constructed. Two rings of NdFeB are cut in axial direction into 32 equal arc segments such that each arc segment subtends an angle of 22.5° at the centre. These arc segments are then parallely magnetized in magnetizer. A ferromagnetic cylinderical yoke is constructed by hinging two ferromagnetic half cylinders along one axial edge. A fixture consisting of a wooden square base, wooden mandrel, stepped and slotted Aluminium cylinder and Aluminium fillers is made to assemble the NdFeB magnets in a ring on both the ends of the ferromagnetic yoke. A Hall effect sensor is instrumented inside the yoke in the middle at radial distance of 34 mm from the axis of the yoke. A ferromagnetic wire rope with a defect is inserted in the novel wire rope tester. It has been successfully shown by performing Non-destructive testing that whenever a defect in a wire rope passes below the Hall-effect sensor instrumented in the wire rope tester developed in this work, a signal is generated indicating the defect.