IMPROVEMENTS IN GAS INDUCING IMPELLER DESIGN

Rate of gas induction, static pressure, mixing time and power consumption have been measured in 0.57 m i.d. vessel. Different types of impellers namely shrouded disc turbine, shrouded curved blade turbine and pitched blade turbine were used. The impeller diameter was varied from 0.15-0.25 m and the impeller speed was varied from 3 to 20 r/s.

The pitched blade turbine was found to give 30-60 per cent higher rates of gas induction as compared with the best design reported in the literature. The mixing time was found to be lower by a similar magnitude. Moreover in the case of pitched blade turbine it was found that the gas was getting induced radially as well as axially. This eliminates the necessity of the diffuser and hence reducing the complexities in the mechanical structure.     

HiveSec: security in resource-constrained wireless networks inspired by beehives and bee swarms

Cryptographic algorithms rely on the strengths of all their fundamental components and expect them to be harmonious in accomplishing desired levels of security in applications. In order for a security solution to be sophisticated and to provide high security (measured in terms of the security goals it satisfies), the solution needs to typically involve complex mathematical operations and/or multiple stages of operation. While these might offer increased security, such solutions might not be applicable to all systems. We refer to resource-constrained wireless networks, such as radio frequency identification and wireless body area networks, where the resources available on-chip are often decided by the balance between device costs, requirements of longevity and usability. The constraints, thus, require designing solutions that use simple logical operations and are based on reuse of functions, while introducing sufficient unpredictability to increase security. In this paper, we present a key management and message signature generation scheme called HiveSec, whose design is inspired by the symmetry in beehives and the nature of bee swarms, and which offers security through unpredictability and reduced resource usage. We validate our work through simulation studies and security analysis.     

Probabilistic Belief Contraction

Probabilistic belief contraction has been a much neglected topic in the field of probabilistic reasoning. This is due to the difficulty in establishing a reasonable reversal of the effect of Bayesian conditionalization on a probabilistic distribution. We show that indifferent contraction, a solution proposed by Ramer to this problem through a judicious use of the principle of maximum entropy, is a probabilistic version of a full meet contraction. We then propose variations of indifferent contraction, using both the Shannon entropy measure as well as the Hartley entropy measure, with an aim to avoid excessive loss of beliefs that full meet contraction entails.     

Consumer Attention to an Over‐the‐counter Warning in Four Different Styles of Design

The study consisted of three objectives: (a) to test the relative prominence and conspicuousness of a warning required by US law to be conspicuous; (b) to explore whether or not the conspicuousness of the said warning can be enhanced graphically; and (c) to develop preliminary data for power analysis that would guide decisions related to sample size in future studies. Seventeen subjects viewed four over‐the‐counter drug packages (each with a different style of warning) along with five other products while wearing an eye tracking device. Four styles of warning were used on the over‐the‐counter drug packages: no outline and no fill, outline and no fill, no outline and fill, and outline and fill. The surface area and the placement of the warnings were held constant across all four designs and were consistent with those on commercially available products. Collected data were broken into five zones: warning, brand name, strength, product benefit and net weight. Despite the fact that US law requires it to be conspicuous, the tested warning was significantly less noticeable than the brand name (objective one) for all dependent variables analyzed (α = 0.05). No significant difference was indicated for the varied warning designs (objective two). This could be because not much can be done to enhance prominence when constrained to the limited space that is typically used for such warnings or because of the limited sample size. Power calculations suggest that a sample size of nearly 200 subjects would be required to detect a 2.5 s mean difference at 80% confidence (objective three). Copyright © 2011 John Wiley & Sons, Ltd.     

Single-crystal relaxor ferroelectric piezoactuators with interdigitated electrodes

We report on the fabrication and performance of (1-x) Pb(Zn(1/3)Nb(2/3))O3-xPbTiO3 (PZN-PT) single-crystal relaxor piezoactuators with interdigitated electrodes patterned on a single surface. An electric field gradient across the sample thickness induces a differential contraction between opposite faces, and it is responsible for the actuation. The samples are poled by energizing the electrodes at 100 degrees C and cooling in a field. Calculations of the piezoelectric response based on a periodically modulated dipolar field yield good agreement with experiment. Discrepancies with the model are ascribed to multidomain formation in the ferroelectric sample as a result of field reversals in the applied electric field along the sample length.     

Synthesis of highly pure and dense 0.9(KNbO3)-0.1(BaNi1/2Nb1/2O3-δ) ceramic with superior magnetic properties

Residual NiO phase is generally detected in 0.9(KNbO₃)–0.1(BaNi_1/2Nb_1/2O_3-δ) (KBNNO) synthesized using NiO as a nickel precursor by solid-state reaction. In this work, NiO phase is found to exist in the form of the residual NiO particles with a size of 100-200 nm using energy dispersive X-ray elemental mapping. These NiO residual particles are eliminated by using nickel acetate as a nickel precursor and a 100% perovskite phase KBNNO is successfully synthesized at as low as 600°C temperature. Furthermore, using the two-step sintering technique, 100% relative density is achieved in this material. The nickel acetate–based KBNNO shows a robust ferromagnetism with the saturation magnetization of 11.42 memu/g and the remanent magnetization of 3.89 memu/g which is 38 times higher than that of previously reported value in NiO-based KBNNO. Thus, a highly pure and fully dense KBNNO ceramic with superior magnetic properties is obtained using nickel acetate and by the two-step sintering method. This is a key step forward in the processing of KBNNO and is likely to have a significant impact on other physical properties of this newly invented and promising photovoltaic perovskite material.     

A Comparative Study of Superconductivity and Thermally Activated Flux Flow of YBa2Cu3O7-δ and YBa2Cu3O7-δ/La1-x-yPrxCayMnO3 Bilayers

Journal of Superconductivity and Novel Magnetism - YBa2Cu3O7-δ/La1-x-yPrxCayMnO3 (YBCO/LPCMO) (x?~?0.31, y?~?0.35) bilayers with fixed ferromagnetic layer thickness...     

The Effect of Colour Contrast on Consumers' Attentive Behaviours and Perception of Fresh Produce

The market for fruits and vegetables has received considerable interest in recent years, with much of its growth attributed to consumer interest in nutrition and health. Quality has been indicated to be the most important factor in produce sales, and appearance is of noted significance with regard to perceived quality. The broad objectives of this research were to identify the impact of simultaneous colour contrast (i.e. the produce viewed through a mesh bag) on (a) attentive behaviours as measured by eye tracking and (b) perceived quality, visual appeal and purchase intention as measured with a Likert scale. To accomplish these objectives, six different types of produce (red apples, oranges, lemons, green apples, purple onions and white onions) were photographed with four differently coloured mesh treatments: the same (as the produce), complementary, complementary‐analogous and analogous. Visual stimuli were then presented during the eye tracking study and in a subsequent questionnaire. Colour contrast was found to have a significant effect on both resultant eye tracking variables [number of visual fixations (p < 0.001) and time spent (p < 0.001)]. Produce shown with mesh of the same, or an analogous colour, induced significantly more visual fixations and more time than those depicted with complementary or complementary‐analogous treatments. Subsequent to the eye tracking study, subjects were shown the stimuli and asked to rate the expected quality, visual appeal and their purchase intention for the 24 photographs (6 types of produce × 4 colour contrasts) by using a Likert scale. Pairwise comparisons suggested that produce packaged in the same or analogous mesh were perceived by subjects to be of higher quality, more visually appealing and evoked a higher level of purchase intention than those packaged in complementary or complementary‐analogous mesh (α = 0.05). Copyright © 2012 John Wiley & Sons, Ltd.