Prediction of mass diffusivity of CO2 into bitumen

The infinite dilution and mutual diffusion coefficients for the CO₂/bitumen system were predicted using existing correlations. Out of seven semi-empirical correlations tested, the Umesi-Danner correlation was found to be best suited for the prediction of gas-liquid infinite dilution diffusion coefficient. For the mutual diffusion coefficient, Teja's method based on the generalized corresponding states principle was successfully used. The predictions are compared with the limited CO₂/bitumen diffusivity data available in the literature.     

Cost analysis of a two unit, three state standby redundant complex system with two types of repair facilities under waiting

This paper deals with the cost analysis of a two unit, three state standby redundant complex system, incorporating the concept of two types of repair facilities, viz. minor and major repair. The concept of waiting time for the major repair of the failed system has also been introduced. The system can suffer from two types of failures, namely catastrophic and partial. Failure and waiting times of units follow exponential time distribution, whereas repair of units follows general time distribution. Using the supplementary variable technique, Laplace transforms of probabilities of the complex system being in various states have been computed. In addition, using Abel's lemma, steady state behaviour has also been examined. Some important graphs have been sketched at the end to highlight the important results.     

Organizational environment and performance of research groups—A typological analysis

In this paper an attempt is made to construct a typology of research units according to a set of organizational features and relate the resulting classification to a set of performance measures. The organizational features include (i) resources and facilities for research; (ii) Communication and transfer of new ideas; (iii) Planning and organization of research; and (iv) Social psychological environment for research. The performance measure include (i) General R&D effectiveness, which essentially connotes the quality dimension of research performance; (ii) Recognition of the work of the research unit by the scientific community; (iii) User-oriented effectiveness; and (iv) Administrative effectiveness (budget and schedule compliance). This study is based on the subset of empirical data on 220 research units collected in India for the third round of the UNESCO International Comparative Study on the Organization and Performance of Research Units (ICSOPRU). Twenty three measures of organizational environment, operationalized by multiple indicators, were chosen as discriminant criteria for the construction of the typology, using a classification computer programme SYSTIT (Systeme' de Typologie Iterative). The relationship between typology groupings and performance measures was analyzed through multiple correspondence analysis. This study brings out that resources and facilities for research are a necessary but not a sufficient condition of performance. The sufficiency condition implies a positive work environment, effective communication within and outside the research group and a conceptually exciting research programme.     

Switched beam dielectric resonator antenna array with six reconfigurable radiation patterns

A single feed, four element rectangular Dielectric Resonator Antenna (DRA) array, with beam switching capability is proposed. A wide impedance bandwidth of more than 25% at the center frequency of 1.95 GHz is achieved. Each DRA has two excitation strips and four parasitic patches. The six cases are discussed; each case corresponds to a diverse radiation pattern. The antenna beam is switched in azimuth (θ = 45°) at Φ = 0°, 60°, 120°, 180°, 240°, and 300°. The antenna gain is found to be more than 7 dB in most of the frequency band of interest. A passive prototype is developed and tested to validate simulation results. The comparison between the simulated and measured reflection coefficients and the radiation patterns for the six cases is presented. A good agreement between the measured and simulated results is observed. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:519–530, 2016.     

Barrier,Biodegradation, and mechanical properties of (Rice husk)/(Montmorillonite) hybrid filler‐filled low‐density polyethylene nanocomposite films

Rice husk (RH)/montmorillonite (MMT) hybrid filler‐filled low‐density polyethylene nanocomposite films were prepared by extrusion blown film. RH was used as a biodegradable filler in various concentrations (2, 5, and 7 parts per hundred composite), while the amount of MMT was held constant at 2 wt%. Delamination of MMT platelets and distribution of RH were investigated by X‐ray diffraction and scanning electron microscopy. Diffractograms revealed the formation of intercalated structures, regardless of the RH content. Barrier properties revealed that MMT platelets have the potential to retard the diffusion of permeating molecules while, on the other hand, barrier efficiency of MMT is balanced by the subsequent incorporation of RH in RH/MMT hybrid filler‐filled composite films. Despite an increase in permeability, the selectivity ratio (CO₂/O₂ permeability) increased with increasing RH contents in the hybrid filler‐filled composite films showing the potential of these films in the development of modified atmosphere for fresh fruits and vegetables. The colonization of fungus and formation of holes as observed in micrographs of the test samples subjected to soil burial revealed that the biodegradation rate increased with the incorporation of RH in the hybrid composites. The composite films with higher contents of RH in hybrid filler are also more biodegradable than those having lower contents. Addition of RH contents in the hybrid filler increased the tensile modulus, while decreasing the tensile and tear strength. Addition of RH in the hybrid filler increased the melting and crystallization temperatures of the resulting nanocomposite films as well. J. VINYL ADDIT. TECHNOL., 23:162–171, 2017. © 2015 Society of Plastics Engineers     

Prediction of high-strength concrete: high-order response surface methodology modeling approach

In the concrete industry, compressive strength is the most essential mechanical property. Therefore, insufficient compressive strength may lead to dangerous failure and, thus, becomes very difficult to repair. Consequently, early, and precise prediction of concrete strength is a major issue facing researchers and concrete designers. In this study, high-order response surface methodology (HORSM) is used to develop a prediction model to accurately predict the compressive strength of high-strength concrete (HSC). Different polynomial degrees order ranging from 2 to 5 is used in this model. The HORSM, with five-order polynomial degree, model outperforms several artificial intelligence (AI) modeling approaches which are carried out widely in the prediction of HSC compression strength. Besides, support vector machine (SVM) model was developed in this study and compared with the HORSM. The HORSM models outperformed the SVM models according to different statistical measures. Additionally, HORSM models managed to perfectly predict the HSC compressive strength in less than one second to accomplish the learning processes. While, other AI models including SVM much longer time. Lastly, the use of HORSM for the first time in the concrete technology field provided much accurate prediction results and it has great potential in the field of concrete technology.

     

Reconfigurable Printed Liquids

Liquids lack the spatial order required for advanced functionality. Interfacial assemblies of colloids, however, can be used to shape liquids into complex, 3D objects, simultaneously forming 2D layers with novel magnetic, plasmonic, or structural properties. Fully exploiting all‐liquid systems that are structured by their interfaces would create a new class of biomimetic, reconfigurable, and responsive materials. Here, printed constructs of water in oil are presented. Both form and function are given to the system by the assembly and jamming of nanoparticle surfactants, formed from the interfacial interaction of nanoparticles and amphiphilic polymers that bear complementary functional groups. These yield dissipative constructs that exhibit a compartmentalized response to chemical cues. Potential applications include biphasic reaction vessels, liquid electronics, novel media for the encapsulation of cells and active matter, and dynamic constructs that both alter, and are altered by, their external environment.     

Isogeometric FEM‐BEM coupled structural‐acoustic analysis of shells using subdivision surfaces

We introduce a coupled finite and boundary element formulation for acoustic scattering analysis over thin‐shell structures. A triangular Loop subdivision surface discretisation is used for both geometry and analysis fields. The Kirchhoff‐Love shell equation is discretised with the finite element method and the Helmholtz equation for the acoustic field with the boundary element method. The use of the boundary element formulation allows the elegant handling of infinite domains and precludes the need for volumetric meshing. In the present work, the subdivision control meshes for the shell displacements and the acoustic pressures have the same resolution. The corresponding smooth subdivision basis functions have the C¹ continuity property required for the Kirchhoff‐Love formulation and are highly efficient for the acoustic field computations. We verify the proposed isogeometric formulation through a closed‐form solution of acoustic scattering over a thin‐shell sphere. Furthermore, we demonstrate the ability of the proposed approach to handle complex geometries with arbitrary topology that provides an integrated isogeometric design and analysis workflow for coupled structural‐acoustic analysis of shells.