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As traditional non-renewable energy sources become scarcer, researchers are exploring effective strategies for producing sustainable and renewable energy. Oxygen evolution reaction through electrocatalytic water splitting (EC-OER) on the surface of a semiconductor has drawn much more attention in the worldwide as it has the principal role towards the several kind of energy applications viz. fuel cell, metal-ion rechargeable batteries and water oxidation. It is extremely difficult to develop eco-friendly, plentiful, and cost-effective nanomaterials as catalysts in order to achieve high efficiency of hydrogen production through water splitting. Furthermore, hierarchical nanostructures will become more valuable in future energy conversion applications due to their excellent physicochemical properties. Herein, we have synthesized total six different kinds of multi-metal-doped porous silica nanomaterials by utilizing the combination of nickel, iridium, and ruthenium metal slats in order to explore them as potential catalysts for electrochemical water oxidation process. We present a simple strategy to synthesize multi-metal-doped silica materials with spherical morphology, deploying a cation surfactant template (CTAB) as a structure directing agent in water-ethanol solvent mixtures. These materials are thoroughly characterized with the help of powder X-ray diffraction (PXRD), UV–Vis, FT-IR, X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FE-SEM), nitrogen-sorption isotherm, thermogravimetric (TGA) analysis. The particles are 550–600 nm in size with a fine-looking spherical morphology and surface area in the range of 111–419 m2/g. Among all of these metal-silica, Ni–Ir–Ru-doped mesoporous silica particles (NIRS) exhibit excellent electrocatalytic activity towards oxygen evolution reaction (100 mA/cm2 current density@0.5V) with long-term durability up to 10 h, and the Tafel slope is also very low (∼68 mV/dec) in 1 M KOH medium. The excellent electrical conductivity of Ni–Ir–Ru-doped silica makes it a superior electrocatalyst due to its spherical morphology, synergistic effects of the multi metallic components, and its hierarchical nanoporous structure. [Display omitted] • A facile method for multi-metal-doped mesoporous silica was developed. • The particle sizes were 550–600 nm and surface area were up to 419 m2/g. • Multi-metal-doped mesoporous silica particles were spherical particles. • NIRS generated 100 mA/cm2 and current density@0.5V during OER in pH=14. • NIRS exhibited high durability up to 10 h with Tafel slope of 68 mV/dec in pH=14. [ABSTRACT FROM AUTHOR]

• Time delays and relative approach of the impactors affect the contact forces. • The relative position and trajectories of the impactors influence the delamination. • The coefficient of friction and impactor size decides the critical angle for gross slip. The impacts occurring in real scenarios can be arbitrary, simultaneously impacting at different trajectories, giving rise to complexity in analysing the impact phenomena. This necessitates the implementation of a robust numerical finite element (FE) model capable of modelling such multiple impacts. The present paper investigates the multiple oblique low velocity impacts (OLVIs) on a clamped GLARE plate by spherical impactors exploring the influence of obliquity and their relative trajectories as well as the time delay between the OLVIs on the impact response and the extent of interfacial delamination. A 3D FE code has been developed considering the Hertzian contact model for modelling the normal component of contact and the theory of Mindlin and Deresiewicz is used for modelling tangential component considering friction. Results show that in addition to the obliquity of the impactors and the coefficient of friction, their relative trajectories, sizes and instant of their occurrences significantly influence the contact force histories, contact durations and the delamination at the interfaces. [ABSTRACT FROM AUTHOR]

The present paper deals with the analytical determination of local flexibility coefficients (LFCs) for a functionally graded (FG) cracked shaft. Finite element (FE) analysis has been performed using two nodded beam element having six degrees of freedom (DOF) at each node and Timoshenko beam theory (TBT) has been used. Material properties are assumed to be graded in radial direction following linear, power law and exponential law gradation respectively. In the present analysis, the mixture of Aluminum Oxide (Al 2 O 3 ) and Stainless Steel (SUS304) is considered as FG material where metal content is considered decreasing towards the outer diameter of shaft. The LFCs of a cracked shaft is derived using Castigliano's theorem and Paris's equations in conjunction with the expression for stress intensity factors. A complete code has been developed using MATLAB program and validated with the existing results available in literatures. The LFCs are calculated for different crack depths and for different crack closer lines for a cracked shaft and the effect of crack depth and crack closer line position on the LFCs has been studied. Numerical results reveal that for a given crack configuration, LFCs values are maximum for metallic, minimum for ceramic shaft and the LFCs for FG shaft in between, and also the LFCs values increase with the increasing power law gradient indices. [ABSTRACT FROM AUTHOR]

Abstract: Present paper deals with the study of stress distribution in the vicinity of a broken carbon nanotube (CNT) in CNT-based fiber reinforced composites. Three dimensional finite elements analysis (FEA) using multi-scale modeling has been done considering a square representative volume element (RVE) and the effect of a broken CNT on the adjacent CNTs and on the matrix has been studied for CNT/Epoxy and CNT/Titanium composites. The distributions of stresses in the broken CNT, at the interface, and in the adjacent CNTs have been analyzed for different volume fractions. It is observed that the ineffective length of the broken CNT is dependent on the volume fraction as well as on the type of matrix materials. The magnitude of the interfacial shear stress as well as the stress concentration in the vicinity of the broken CNT is also influenced by the fiber volume fraction and the type of matrix materials. [Copyright &y& Elsevier]

Abstract: The present paper deals with the study of hybridization on impact response and impact induced delamination of laminated composite plates with holes. Three dimensional finite element analysis has been done to evaluate the response of graphite/epoxy laminate as well as graphite/epoxy–kevlar/epoxy hybrid laminate subjected to impact loading, and stress based delamination criterion has been used to assess the chances of delamination initiation from the inner edges of the hole at different interfaces. The present study concludes that incorporation of kevlar/epoxy at the outer layers of the [0/−45/45/90]2S in the graphite/epoxy laminate improves the impact resistance of the laminate in terms of reduced magnitude of the contact force but the chances of impact induced delamination at the interfaces increase. [Copyright &y& Elsevier]

Abstract: In the present paper a 3D finite element analysis has been performed for assessing delamination at the interfaces of graphite/epoxy laminated fiber reinforced plastic composites subjected to low velocity impact of multiple cylindrical impactors. Eight nodded layered solid elements have been used for the finite element analysis of fiber reinforced plastic laminates. Newmark-β method along with Hertzian contact law has been used for transient dynamic finite element analysis and an algorithm has been developed for determining the response of the laminated plate under the multiple impacts at different time. Appropriate delamination criterion has been used to assess the location and extent of delamination due to multiple impacts. A study has been carried out to observe the effects of important parameters on the impact response of the laminate and the delamination induced at the interfaces. It has been observed that the contact force magnitude as well as delamination at the interface are greatly influenced by the time interval between successive multiple impacts. [Copyright &y& Elsevier]

A simple and computationally efficient adaptive finite element analysis strategy has been adopted for accurate and reliable evaluation of contact force and stresses in FRP composite laminates subjected to transverse impact. Stress based delamination criterion has been utilized to study the initiation of delamination. Hence importance of reliable estimation of stresses is very important for proper prediction of delamination. Contact of a spherical and cylindrical impactor on FRP composite laminates are considered. Studies have clearly shown the importance of appropriate finite element mesh for reliable prediction of delamination initiation and growth. A good number of cases have been considered with varying stacking sequences and using appropriate finite element mesh for studying the vulnerability of composite laminates towards delamination when subjected to transverse impact. [Copyright &y& Elsevier]

• It aims to design optimal surface textures on implant to enhance its biologic fixation with the host bone. • Three representative initial implant surface textures were chosen based on an earlier investigation. • A combined finite element(FE)-neural network(NN)-genetic algorithm(GA) approach was implemented. • NNs substitutes tedious FE analyses to predict bone growth while, optimization of the geometric features of implant surfaces has been solved using GA. The surface features on implant surface can improve biologic fixation of the implant with the host bone leading to improved secondary (biological) implant stability. Application of finite element (FE) based mechanoregulatory schemes to estimate the amount of bone growth for a wide range of implant surface features is either manually intensive or computationally expensive. This study adopts an integrated approach combining FE, back-propagation neural network (BPNN) and genetic algorithm (GA) based search to evaluate optimum surface macro-textures from three representative implant models so as to enhance bone growth. Initial surface textures chosen for the implant models were based on an earlier investigation. Based on FE predicted dataset, a BPNN was formulated for faster prediction of bone growth. Using the BPNN predicted output, a GA-based search was carried out to maximize bone growth subject to clinically admissible micromotion at the bone-implant interface. The results from FE analysis and bone growth predictions from the BPNN were found to have strong correlation. The optimal osseointegration-maximized-textures (OMTs) obtained were found to offer enhanced biological fixation, as compared to that offered by the textures in the initial models. Results from the present study reveal that certain reduction in the dimension of ribs/grooves promotes bone growth. However, periodic patterns of ribs with higher and lower rib dimensions provide uniform stress environment at the interface thus promoting osseointegration. [ABSTRACT FROM AUTHOR]

We report a new secondary amine linked triazine and pyrene containing microporous organic polymer (TrzPyPOP) through the polycondensation reaction and it is used as a very efficient organocatalyst for the synthesis of dihydropyrimidones via multicomponent coupling reaction. [Display omitted] • A new secondary amine linked triazine and pyrene containing microporous organic polymer (TrzPyPOP) is reported. • Polycondensation reaction between tetramine and monoaldehyde resulted N-rich POP with high BET surface area. • High surface area and N-rich basic sites are explored in heterogeneous organocatalyst. • High yield synthesis of dihydropyrimidones are reported via three-component coupling reaction. • Dihydropyrimidones yields are 88–99 % together with high recycling efficiency under the optimum conditions. Materials with high specific surface area and bearing abundant basic sites at their pore surface are very demanding as heterogeneous catalyst for the eco-friendly base catalyzed reactions. Here we have developed a new secondary amine linked triazine and pyrene containing microporous organic polymer (TrzPyPOP) through a simple polycondensation reaction between tetramine1,4-bis(4,6-diamino-s-triazin-2-yl)-benzene (SL-1) and monoaldehyde pyrene-1-carboxaldehyde. This new porous organic polymer TrzPyPOP is very rich in N-content with high BET surface area (1016 m2 g−1). High surface area and N-rich surface basic sites have been explored in its potential as heterogeneous organocatalyst for the synthesis of dihydropyrimidones via Biginelli condensation involving three-component coupling reaction. Only a very little amount of catalyst was effective for the synthesis of dihydropyrimidones derivatives (yields = 88–99 %) together with high recycling efficiency under the optimum reaction conditions. [ABSTRACT FROM AUTHOR]

The development of a robust, sustainable and inexpensive bifunctional material for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) via electrochemical overall water splitting is very challenging and essential for energy generation and conversion processes. Herein, we have developed two 3d transition metals Ni(II) and Cu(II)-porphyrin based conjugated microporous polymeric electrocatalysts having high specific surface areas (1400 and 1350 m2g−1). Both catalysts showed good performance towards overall water splitting under alkaline pH conditions. These metal-coordinated porous polymers Ni-Por-Py and Cu-Por-Py are well characterized using different analytical instruments. Ni-Por-Py and Cu-Por-Py displayed a low overpotential of 213 mV and 250 mV, respectively to attend a current density of 10 mA/cm2 for HER using Ni-foam as substrate. The OER activity under alkaline condition with an overpotentials of 164 and 170 mV for Ni-Por-Py and Cu-Por-Py, respectively were achieved to drive a current density of 10 mA/cm2 under similar conditions. The excellent electrocatalytic activity of Ni-Por-Py and Cu-Por-Py could be attributed to the presence of transition metal coordinated porphyrin building blocks in the π-conjugated polymer skeletons, which facilitates the electron transfer processes along with inherent microporosity and high surface areas. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The most important factor that governs the performance of a radial basis function network (RBFN) is the optimization of the network architecture, i.e. determining the exact number of radial basis functions (RBFs) in the hidden layer that can best minimize the error between the actual and network outputs. This work presents a genetic algorithm (GA) based evolution of optimal RBFN architecture and compares its performance with the conventional RBFN training procedure employing a two stage methodology, i.e. utilizing the k-means clustering algorithm for the unsupervised training in the first stage, and using linear supervised techniques for subsequent error minimization in the second stage. The validation of the proposed methodology is carried out for the prediction of flank wear in the drilling process following a series of experiments involving high speed steel (HSS) drills for drilling holes on mild-steel workpieces. The genetically grown RBFN not only provides an improved network performance, it is also computationally efficient as it eliminates the need for the error minimization routine in the second stage training of RBFN. [ABSTRACT FROM AUTHOR]