Trust management for e-transactions

There has been enormous increase in transactions and cooperative-computing services on the internet. This is both a technical and a social phenomenon. Transactions and services over the internet have global reach and users, known or unknown to the service provider, might be interested in availing access or participating in the cooperative transaction in a distributed manner. Thus, it is very important for service providers to identify and establish trustworthiness of potential collaborators, which they do by writing contracts (e.g. access control, security policies; the words contract and policy are used interchangeably) without violating the privacy and confidentiality laws that prevail across geographical boundaries. But as the system becomes complex and dynamic, contractual incompleteness arises since it becomes cumbersome to mention potentially large set of outcomes of the user's choice of action. Trust plays a crucial role in the design of optimal contracts; not all the relevant, valuable information on the user's choice of action is incorporated in the equilibrium contract. It may also be noted in that traditional transactions, the notion ofseeing is believing plays a vital role. However, in e-transactions, this is not the case. The challenge is to see how in such a scenario trust can indeed be generated. Note that the presence of trust facilitates cooperative behaviour and allows for exchange to occur in situations where its absence would preclude trade. In this paper, we shall present a comparative analysis of various approaches of trust management in practice that integrates technology with other factors. We shall also bring out the relative deficiencies and how these issues are tackled in our ongoing work that facilitates execution of optimal contracts.     

Polyaniline–CdS nanocomposites: effect of camphor sulfonic acid doping on structural, microstructural, optical and electrical properties

Nanocomposites of CdS nanocrystals with conducting polyaniline doped with camphor sulfonic acid (CSA) have been prepared by spin coating technique and investigated by X-ray diffraction, field emission scanning electron microscopy (FESEM), fourier transform infra red spectroscopy (FTIR), UV–visible spectroscopy and electrical transport method. The X-ray diffraction patterns showed broad peaks due to formation of nanoparticles of CdS in polyaniline matrix. FESEM showed that the transformation of morphology from agglomeration to nanopetals. The FTIR spectra confirmed the interaction between CSA and polyaniline (PANi)–CdS nanocomposite. The UV–visible spectrums revealed the enhancement of doping level for the PANi–CdS nanocomposites which is assigned to the existence of greater number of charges on the polymer backbone. DC electrical conductivity studies showed an increase in conductivity of PANi–CdS nanocomposites from 6.9?×?10^?6 to 3.14?×?10^?4 due to addition of CSA (10–50?%).     

Development of an Automated Method for Folin‐Ciocalteu Total Phenolic Assay in Artichoke Extracts

Abstract: We developed a system to run the Folin‐Ciocalteu (F‐C) total phenolic assay, in artichoke extract samples, which is fully automatic, consistent, and fast. The system uses 2 high performance liquid chromatography (HPLC) pumps, an autosampler, a column heater, a UV/Vis detector, and a data collection system. To test the system, a pump delivered 10‐fold diluted F‐C reagent solution at a rate of 0.7 mL/min, and 0.4 g/mL sodium carbonate at a rate of 2.1 mL/min. The autosampler injected 10 μL per 1.2 min, which was mixed with the F‐C reagent and heated to 65 °C while it passed through the column heater. The heated reactant was mixed with sodium carbonate and color intensity was measured by the detector at 600 nm. The data collection system recorded the color intensity, and peak area of each sample was calculated as the concentration of the total phenolic content, expressed in μg/mL as either chlorogenic acid or gallic acid. This new method had superb repeatability (0.7% CV) and a high correlation with both the manual method (r²= 0.93) and the HPLC method (r²= 0.78). Ascorbic acid and quercetin showed variable antioxidant activity, but sugars did not. This method can be efficiently applied to research that needs to test many numbers of antioxidant capacity samples with speed and accuracy.     

Modeling of friction-stir butt-welds and its application in automotive bumper impact performance Part 2. Impact modeling and bumper crash performance

Ever increasing requirements regarding vehicle safety have led to rapid developments in various joining process. Among FSW widely used for Aluminum alloy welded structure of car body because of their remarkable performance in welding. For a better understanding of this performance, it is necessary to determine the behavior of butt weld in service conditions. In earlier phase of this study, thermo mechanical simulations and analysis are performed to understand the thermal behavior in the FSW weld zones. The developed models are correlated against published experimental results in terms of temperature profile of the weld zone. The objectives of the second part of this work is to develop and demonstrate an FE model of bumper and crash box assembly that would improve on the current modeling techniques for the mechanical response of welds in structural problems.     

Photoactive Earth‐Abundant Iron Pyrite Catalysts for Electrocatalytic Nitrogen Reduction Reaction

The generation of ammonia, hydrogen production, and nitrogen purification are considered as energy intensive processes accompanied with large amounts of CO₂ emission. An electrochemical method assisted by photoenergy is widely utilized for the chemical energy conversion. In this work, earth‐abundant iron pyrite (FeS₂) nanocrystals grown on carbon fiber paper (FeS₂/CFP) are found to be an electrochemical and photoactive catalyst for nitrogen reduction reaction under ambient temperature and pressure. The electrochemical results reveal that FeS₂/CFP achieves a high Faradaic efficiency (FE) of ≈14.14% and NH₃ yield rate of ≈0.096 µg min^?1 at ?0.6 V versus RHE electrode in 0.25 m LiClO₄. During the electrochemical catalytic reaction, the crystal structure of FeS₂/CFP remains in the cubic pyrite phase, as analyzed by in situ X‐ray diffraction measurements. With near‐infrared laser irradiation (808 nm), the NH₃ yield rate of the FeS₂/CFP catalyst can be slightly improved to 0.1 µg min^?1 with high FE of 14.57%. Furthermore, density functional theory calculations demonstrate that the N₂ molecule has strong chemical adsorption energy on the iron atom of FeS₂. Overall, iron pyrite‐based materials have proven to be a potential electrocatalyst with photoactive behavior for ammonia production in practical applications.     

Structural, electrical and magnetic properties of copper substituted Zn–Mn ferrites

Optimum composition (x = 0.0–0.75) of copper substituted Zn_0.25Mn_0.75?xCu_xFe₂O₄ ferrites system have been synthesized by simple chemical co-precipitation method. X-ray diffraction pattern of all samples shows characteristic features of nanocrystalline cubic spinel structure of ferrites. The average grain size of the samples was measured using scanning electron micrographs. The saturation magnetization, coercivity and remanance were studied as a function of copper content in the host ferrite materials. Electrical resistivity of the samples was measured by two probe method. The semiconducting nature of the samples was noted from variation of electrical resistivity with temperature. The effect of copper substitution in ferrites was studied through the measurements of structural, electrical and magnetic properties.     

Study on effect of diverse air inlet arrangement on thermal management of cylindrical lithium-ion cells

Lithium-ion cells are preferred in the electrical powertrain due to high-power density, compactness, and modularity. In real driving conditions, the cells undergo discharge rates as high as 4 C resulting in high heat generation affecting the performance. To obtain the maximum performance the pack construction and thermal management of cells are crucial parameters. In our work, air-cooled technique with diverse air inlet and staggered scheme with a two-channel partition approach for thermal management of the cylindrical lithium-ion cells are studied in computational fluid dynamics. The simulation model is validated with experimental results. The obtained results demonstrate that the cells in the dual-directional air inlet arrangement had low maximum temperature difference among and within the cells and required least fan work. This arrangement required least fan work to generate optimal air inlet velocity of 2 m/s for 1, 2, and 3 C and 4 m/s for 4 C discharge rates. There is a reduction of 50% and 33% fan work for 3 and 4 C discharge rates, which are the majority operating points. Also, it shows that the temperature uniformity within the cells has improved. The results of this study can used to optimize parameters for designing an enhanced thermal management system.     

Spectral analysis of infant cries and adult speech

In this paper, spectrographic analysis of the infant cries is reported. For the spectrographic analysis of the infant cries ten different cry modes are used to analyze differences in different pathological cries. A comparison of spectrograms of the adult speech signal and infant cry signals is given. Based on differences in the distribution of energy in the spectrograms, energy-based features are calculated from the short-time Fourier transform (STFT) of the adult speech and infant cry signals. The classification performance of these features is obtained using support vector machine (SVM) classifier and it is observed that the energy distribution in 0–1 kHz range is promising feature in the classification of adult speech and infant cries and the classification accuracy achieved with this feature is 98.22 %. On the contrary, it was observed that it is very difficult to classify adult speech and infant cries using the energy distribution in 1–3 kHz.     

A new controller for boost dc–dc converters based on a novel sliding surface

ABSTRACT

In this paper, two control schemes for boost converters affected by uncertainties in input voltage and load are proposed. The boost converter dynamics is redefined in terms of new state variables to facilitate the use of a disturbance observer that can estimate matched and unmatched disturbances. A sliding surface, which is new in the context of boost converters, is proposed to enable tracking and regulation of output voltage without requiring measurement of input voltage and load current. The stability of the overall system including the disturbance observer, the sliding variable and the output is proved. The performance of the schemes is assessed for regulation of output voltage and tracking of reference voltage by simulation as well as experimentation in which various types of uncertainties and various types of reference voltages are considered.     

Conductivity and atmospheric aging studies of polypyrrole-coated cotton fabrics

Polypyrrole (PPy) is one of the preferred alternatives among the intrinsically conductive polymers (ICPs). In this study, PPy-coated cotton (PPy-CT) fabrics were synthesized by two step in situ chemical polymerization. The reaction parameters, such as monomer concentration and temperature, were studied in detail. The surface resistivity of PPy-CT fabrics ranged ∼ 15–5000 Ω⁻². To assess long-term usage potential, the atmospheric aging of conductivity characteristics of treated fabrics was monitored over a period of 6 months. It was found that the synthesis temperature had a significant impact on conductivity and atmospheric aging of PPy-CT fabrics. Furthermore, various sulfonic acid sodium salts added as external doping agents during polymerization also had a positive effect. The scanning electron microscopy revealed smoother morphology of sulfonic acid salt doped PPy coatings. The overall study addresses the durability aspect of PPy-CT fabrics in potential applications areas. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012