An Efficient and Scalable Quasi-Aggregate Signature Scheme Based on LFSR Sequences

Aggregate signatures can be a crucial building block for providing scalable authentication of a large number of users in several applications like building efficient certificate chains, authenticating distributed content management systems, and securing path vector routing protocols. Aggregate signatures aim to prevent resources (signature and storage elements, and computation) from growing linearly in the number of signers participating in a network protocol. In this paper, we present an efficient and scalable quasi-aggregate signature scheme, {rm CLFSR}- {rm QA}, based on third-order linear feedback shift register (cubic LFSR) sequences that can be instantiated using both XTR and GH public key cryptosystems. In the proposed {rm CLFSR}-{rm QA} construction, signers sign messages sequentially; however, the verfier need not know the order in which messages were signed. The proposed scheme offers constant length signatures, fast signing, aggregation, and verification operations at each node, and requires the least storage elements (public keys needed to verify the signature), compared to any other aggregate signature scheme. To the best of our knowledge, {rm CLFSR}- {rm QA} is the first aggregate signature scheme to be constructed using LFSR sequences. We believe that the {rm CLFSR}- {rm QA} signature scheme can be catalytic in improving the processing latency as well as reducing space requirements in building secure, large-scale distributed network protocols. We perform extensive theoretical analysis including correctness and security of {rm CLFSR}- {rm QA} and also present a performance (computation and communication costs, storage overhead) comparison of the proposed scheme with well-known traditional constructions.     

Quick and reliable estimation of BOD load of beverage industrial wastewater by developing BOD biosensor

An amperometric biosensor for determination of biochemical oxygen demand in wastewater has been developed to overcome the time consuming monitoring procedures. The performance and stability of the immobilized membrane have been investigated at 37 °C and pH 6.8. Immobilized microbial membranes maintain their stability and activity after intermittent use for 400 cycles when stored at 4 °C in sodium phosphate buffer pH 6.8. The response time of the BOD sensor was only 90 min, being independent of the concentration, and the lower detection limit was 1 mg/l. The obtained BOD values showed correlation with that of the conventional method for BOD determination (BOD5) with a deviation of ±10%. Moreover, the sensor exhibits good repeatability (3.39–4.45%) and reproducibility (1.85–2.25%). Software was added to upgrade this sensor and to make it a promising candidate for online monitoring.     

Integrating Safety Critical Software System in Probabilistic Safety Assessment

In the recent times, computer-based systems are frequently used for protection and control of Nuclear Power Plants (NPPs). In the conventional Probabilistic Safety Assessment (PSA), the contribution from software in these computer-based systems was not given necessary attention. However, from operating experience, it has been found failures in such systems can also result in initiating events that have the potential for leading into Core Damage in the event of unavailability of the respective Engineered Safety Features. The impact of a typical computer-based system on PSA of Indian Nuclear Power Plant is demonstrated.     

Optimisation of Detergent Ingredients for Stain Removal Using Statistical Modelling

Artificially soiled test fabrics are widely used to study the cleaning performance of detergents formulations. In this study, artificial soiled cotton test fabrics were prepared in the laboratory using carbon black as a model soil. Design of experiments was used to optimise the concentration of detergent ingredients for stain removal. A multi‐factorial analysis of variance was used to model the effect of sodium dodecylbenzene sulfonate, nonylphenol ethoxylate, sodium silicate, sodium citrate and sodium carbonate as builders on soil removal. A colourimetric evaluation using the CIELAB system was used to measure soil removal. In general, performance increases with increasing concentration of surfactant, silicate and soda ash.     

Interaction of lanthanide and actinide with BaHfO3 perovskite: A case study with cerium and uranium

Speciation of actinide (An) and lanthanide (Ln) in technologically important ceramics is very important from both fundamental as well as technological aspects. The intrinsic structural flexibility of perovskite containing AO₆ and BO₁₂ polyhedra makes them suitable and rich hosts for An and Ln. In this work, emphasis was given to deciphering information such as oxidation state, local dopant site, charge compensating defects, excited state kinetics, and so forth in BaHfO₃ (BHO) related to dopant uranium (BHO-U) and cerium (BHO-Ce). Several spectroscopic techniques namely, time-resolved photoluminescence (TRPL), positron annihilation lifetime spectra (PALS), and thermoluminescence (TL) spectroscopy coupled with density functional theory (DFT) were employed to probe the same. Ce and U though are distributed at both Ba and Hf sites, Ce prefers the former, while U prefers the latter site. Uranium on the other hand stabilizes as U⁶⁺ in the form of octahedral uranate ion giving green emission. PALS suggested the formation of defects in BHO-Ce and BHO-U with oxygen vacancies predominating in the former whereas BHO-U perovskites are loaded with cation vacancies and vacancy clusters. These cation vacancies are responsible for lower TL output in BHO-U. TL measurements also suggested cerium doping leads to a higher density of deeper traps in BHO-Ce compared to uranium doping in BHO-U which is in concurrence with DFT results and may have implications in designing afterglow phosphors based on perovskite. We believe this work would have a long-term impact on exploring the potential of perovskite for nuclear waste host and afterglow phosphors applications.     

Interactions of Polyacrylamide with Cationic Surfactants: Thermodynamic and Surface Parameters

The aggregation behaviour of two cationic surfactants, viz. cetyl trimethyl ammonium bromide (CTAB) and N-cetyl pyridinium chloride (CPC), in different concentrations of water-soluble polyacrylamide has been studied in alkaline medium by electrical conductivity and surface tension measurements. A decrease in the critical micelle concentration (CMC) of the surfactant with an increase in polymer content in the mixture was observed. The thermodynamic and surface parameters have been determined and discussed. The results indicate that micellisation becomes more favourable at higher polymer content.     

Hybrid connection algorithm: A strategy for efficient restoration in WDM optical networks

In present communication, we propose a modified resource allocation strategy, namely, hybrid connection algorithm, for achieving efficient restoration in WDM optical networks. The main theme of the algorithm is that, while attempting connection establishment, a wavelength is reserved in advance for providing resources for backup lightpaths. The analysis and the comparison of the proposed strategy with other existing strategies has been undertaken using metrics such as, restoration efficiency, number of wavelength links used by primary and backup lightpaths, and the percent link utilization. The proposed strategy provides 100% restoration efficiency and much better performance than the existing techniques.     

Emphasis on Validation in Research: A Meta-Analysis

The emphasis of validity as a publication content was investigated in dissertations and journal articles. The time of first publication, longitudinal publication profile, ratio of articles to dissertations, and time lag between dissertations and articles emphasizing validity were compared within and among various fields. A three-decade gap separated the first field adopting validity-related contents in its dissertations from the latest fields that did so. The longitudinal data suggested three groups of fields (Agricultural Sciences, Applied Sciences and Social Sciences) which showed consistent differences among groups and consistent similarities within groups in their emphasis on validity-related content. Adoption of validity-related content in dissertations always preceded adoption of validity-related content in journal articles. On average, less than 4% of journal articles included validity-related content across fields. These findings support the hypothesis that validity has been introduced and disseminated within fields following patterns predicted by diffusion of innovations theory. It is argued that this pattern is inconsistent with an efficient and interdisciplinary utilization of available knowledge. Policy recommendations are made for developing strategic communication and education programs for academicians and journal reviewers.     

Nonlinear thermoacoustics of ducted premixed flames: The influence of perturbation convection speed

When a premixed flame is placed within a duct, acoustic waves induce velocity perturbations at the flame’s base. These travel down the flame, distorting its surface and modulating its heat release. This can induce self-sustained thermoacoustic oscillations. Although the phase speed of these perturbations is often assumed to equal the mean flow speed, experiments conducted in other studies and Direct Numerical Simulation (DNS) conducted in this study show that it varies with the acoustic frequency. In this paper, we examine how these variations affect the nonlinear thermoacoustic behaviour. We model the heat release with a nonlinear kinematic G-equation, in which the velocity perturbation is modelled on DNS results. The acoustics are governed by linearised momentum and energy equations. We calculate the flame describing function (FDF) using harmonic forcing at several frequencies and amplitudes. Then we calculate thermoacoustic limit cycles and explain their existence and stability by examining the amplitude-dependence of the gain and phase of the FDF. We find that, when the phase speed equals the mean flow speed, the system has only one stable state. When the phase speed does not equal the mean flow speed, however, the system supports multiple limit cycles because the phase of the FDF changes significantly with oscillation amplitude. This shows that the phase speed of velocity perturbations has a strong influence on the nonlinear thermoacoustic behaviour of ducted premixed flames.