Dielectric and conducting behavior of pyrene functionalized PANI/P(VDF‐co‐HFP) blend

Herein, we present the dielectric and electrical conductivity properties of the partially miscible polymer blend prepared using pyrene functionalized polyaniline (pf‐PANI) and poly(vinylidene fluoride‐co‐hexafluoro propylene) (PVDF‐co‐HFP). The blend mostly retains the fluorescent nature of pf‐PANI as well as can be moldable and possesses good damping property. The dielectric properties have been investigated as a function of temperature at three different frequencies and the plausible origin of polarization responsible for dielectric behavior in this blend has been identified. The experimental results of dielectric measurements are compared with theoretical models and discussed. The surface morphology of the samples has been examined with a scanning electron microscope. The electrical conductivity has also been studied as a function of temperature and explained in terms of hopping of charge carriers/interconnected networks. The combined dielectric and conductivity results together with scanning electron microscope micrographs, reveal that there is hindrance to achieve percolation threshold even after pf‐PANI addition of 57 vol % and subsequent thermal treatment. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44077.     

Evaluation of kinetics and transport mechanism of solvents through natural rubber composites containing organically modified gadolinium oxide

The solvent transport properties of the prepared composites were analysed using solvents of varying cohesive energy density and the effect of both modified as well as unmodified filler on the sorption and diffusion behaviour of NR vulcanisates has been investigated. It is found that the equilibrium uptake decreases with increase in filler content, as anticipated owing to the restrictions offered by the filler for solvents to diffuse into the polymer matrix. The mechanism of transport in natural rubber composites was carefully tracked and it was found to exhibit an anomalous mode of solvent transport where the polymer relaxation is in par with the rate of diffusion. Theoretical modelling of the swelling parameters was done and the results were found to be in agreement with existing models. The excellent swelling resistance coupled with the simultaneous improvement in mechanical properties would definitely pave way for the utilisation of these composites as barrier membranes.     

Non-uniform Euler-Bernoulli beams under a single moving oscillator: An approximate analytical solution in time domain

Dynamic responses of simply supported non-uniform beams traversed by a moving oscillator are analysed in this paper. An approximate analytical method based on Rayleigh-Ritz (R-R) formulation is developed. The fundamental approximate mode obtained from R-R method is used in the present formulation to determine the responses of the beam and the oscillator. Effects of surface irregularities on the displacement and acceleration responses of the beam and the vehicle are also analysed. The results are compared with those obtained using Finite element method (FEM). A numerical example is provided to illustrate the validity of the present method which shows that the proposed method is simple, computationally more efficient compared to FEM and gives fairly good results. Though the single-mode approach used in the present paper is a classical one and numerous studies on the responses of uniform beams under moving loads have been reported in the past, its application to non-uniform beams (for which there does not exist any closed form expression for mode shapes) under a moving load, especially a moving oscillator, is presented for the first time.     

An index to characterize gas-solid and solid-solid mixing from average volume fraction fields

A mixing index based on solid volume fraction fields is developed for gas-solid flows. Conventional mixing indices are based on particle realizations of granular mixing and are applicable to experimental data or discrete element method simulations. However, these indices cannot be used as-is for multifluid models, and an index for characterizing mixing in gas-solid flows from continuous fields is needed. The performance of the new mixing index is tested in two applications. The first is a 3D simulation of the mixing of biomass and sand in a fluidized bed reactor, and the second is a 2D simulation of binary particle segregation in a fluidized bed. The simulations are performed using OpenFOAM®. The mixing index is used to quantify gas-solid mixing using solid volume fractions and solid-solid mixing using solid fractions. The formulation of conventional mixing indices is extended to be used with solid volume fractions fields, and methods for performance improvement are presented.     

Gelatin‐carbohydrate phase‐separated hydrogels as bioactive carriers in vaginal delivery: Preparation and physical characterizations

The current study focuses on the alteration of properties of the gelatin hydrogels using polysaccharides (e.g., maltodextrin, dextran, and sodium carboxymethyl cellulose) for probable use in vaginal delivery of antimicrobials. The hydrogels were prepared by varying the proportions of gelatin and polysaccharides and were characterized by microscopy, mechanical testing, and impedance spectroscopy. Metronidazole (MZ), drug of choice for the treatment of bacterial vaginosis, was incorporated within the hydrogels. In vitro release studies of MZ from the hydrogels was studied in‐depth using modified Franz's diffusion cell. Antimicrobial efficiency of the MZ‐loaded hydrogels was tested against E. coli and B. subtilis. The results suggested that the incorporation of polysaccharides resulted in the phase‐separated hydrogels. The properties of the hydrogels was found be suitable for vaginal delivery. The drug release and antimicrobial efficiency from the hydrogels suggested that the developed hydrogels may be used for the delivery of antimicrobials in the vaginal lumen. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40445.     

Concurrent optimisation of a computer vision system’s multiple responses

A number of recent research works have focused on how to improve the performance of production systems. This paper examines the system based on a simulation model with two manufacturing cells under a re-entrant environment. With the model a set of experiments has been carried out to study how the factors influence the system performance. Different release times and lot sizes have been compared, and scheduling heuristics for both bottleneck and non-bottleneck have been discussed to capture the essence of the production system. We used ANOVA to analyze the experimental results and achieved the conclusions that: interval releasing is better than beginning releasing; lot size can improve one of the performance indicators, but deteriorate the other under interval releasing; NC policy can obtain both good due-date performance and high throughput.     

Prediction of back break in blasting using random decision trees

Back break is an unsolicited phenomenon caused due to rock condition, blast geometry, explosive and initiation system in mines. It does not help in creating a smooth high wall and free face for next blasting due to cracks, overhang and under-hang. It can cause rockfall during drilling due to the cracks present in the in situ rock mass at the perimeter. Due to improper free face created from the previous blast and the presence of loose strata in the face increases the overall cost of production. Therefore, predicting and subsequently optimising back break shall reduce their problems to some extent. In this paper, an attempt is made to predict back break using the random forest method. The variables used for the study was such as burden to spacing ratio, stemming to hole-depth ratio, p-wave velocity and the density of explosive. For the random forest model, R² 0.9791 and RMSE 0.87899 and for linear regression was R² was 0.824 and root mean square error (RMSE) 0.72, respectively. From the field trials, it was evident that the use of low-density emulsion can help in reducing the back break and optimise the overall cost of the blasting process. The same results were validated using Random forest method wherein the model R² was 0.9791 and RMSE was 0.8799.

     

Diversity in cascaded N*Nakagami channels

Short term fading conditions that are worse than those existing in typical Nakagami channels can be modeled using the cascaded approach where the received signal-to-noise ratio is treated as the product of N identical or nonidentical random variables that are either dependent or independent. Cascaded channels also permit the modeling of fading seen in amplify and forward relaying channels as well as keyhole channels. The simplest of these models, referred to as the N*Nakagami model, assumes that the received signal to noise ratio is the product of N independent and identically distributed gamma variables. The fading mitigation achieved in such cascaded channels through diversity is studied in this work. Through analytical approach and simulation, the performance of wireless channels is examined for the selection combining, equal gain combining, generalized selection combining, and maximal ratio combining algorithms. Results demonstrate the existence of severe degradations in cascaded fading channels and the comparative usefulness of the various algorithms in improving the data transmission capabilities. Even though the analysis was undertaken for the case of a coherent binary shift keying modem, results can easily be extended to other modems.     

Effects of Clinorotation on Growth and Chlorophyll Content of Rice Seeds

Microgravity, as a different environment, has been shown to affect plant growth and development (Sievers et al. 1996; Sack 1997). In the present study, effects of slow clinorotation (2 rpm) on growth and chlorophyll content in rice (variety: PRH-10) seedlings were investigated. Rice seeds were clinorotated continuously for 3, 5 and 7 days under ambient conditions. Root and shoot lengths and weights of rice seedlings were measured on the third, fifth and seventh day. Chlorophyll was extracted using N, N-Dimethylformamide (DMF). Absorption and fluorescence spectra of chlorophyll were recorded. Chlorophyll a, chlorophyll b and total chlorophyll contents were calculated from absorption spectra using Arnon’s method. Results showed an increase in root and shoot lengths in clinorotated samples. Similar results were obtained for root and shoot weights. Absorption spectra of chlorophyll showed no shift in the absorption peaks. Chlorophyll content was increased in clinorotated samples as compared to the controls. Interestingly, the difference between chlorophyll content in control and clinorotated samples decreased as the number of days of clinorotation increased. Chlorophyll a/b ratio was lowered in clinorotated samples as compared to the controls. These results suggest that slow clinorotation (2 rpm) affects plant growth and chlorophyll content in rice seedlings.