A new organic ligand, 5-(carboxyformamido)isophthalic acid (5-CFIA), was prepared and employed for the synthesis of two compounds M3(C10H4O7N1)2(8H2O)·H2O (M = Cd, Mn). The compounds have ...three-dimensionally extended structures. Both the compounds were found to be luminescent at room temperature. The luminescence nature was exploited for the detection of Hg2+ ions in an aqueous medium with good selectivity. The interactions between Hg2+ ions and the compounds quench the luminescence intensity and act as a turn-off sensor. Both the compounds exhibited low limits for the detection of Hg2+ ions and in the range mandated by the WHO. The interactions between Hg2+ ions and the compound involve the −NH group, which was probed using Raman and IR spectroscopic techniques. These studies provide important pointers toward the mechanism of this turn-off luminescence behavior. The compounds were explored for base-catalyzed aldol condensation and Lewis acid-promoted β-enaminoester formation reactions. The aldol condensation reaction uses the −NH functionality as a base. The studies indicate that the electron-withdrawing group produces products with higher yields. The β-enaminoester reaction uses the Lewis acid centers, and the studies reveal that the electron-withdrawing groups produce lesser yields of the products. The catalytic nature of the reaction and recyclability of the catalysts were also established. The catalytic reactions employ ethanol (aldol condensation) and no solvent (β-enaminoester), which suggests that the reactions are green and environmentally friendly. The Mn compound was observed to be anti-ferromagnetic.
In this paper, the bending and the free flexural vibration behaviour of sandwich functionally graded material (FGM) plates are investigated using QUAD-8 shear flexible element developed based on ...higher order structural theory. This theory accounts for the realistic variation of the displacements through the thickness. The governing equations obtained here are solved for static analysis considering two types of sandwich FGM plates, viz., homogeneous face sheets with FGM core and FGM face sheets with homogeneous hard core. The in-plane and rotary inertia terms are considered for vibration studies. The accuracy of the present formulation is tested considering the problems for which three-dimensional elasticity solutions are available. A detailed numerical study is carried out based on various higher-order models to examine the influence of the gradient index and the plate aspect ratio on the global/local response of different sandwich FGM plates.
► Static and dynamic response of sandwich structures studied using QUAD-8 shear flexible element. ► Plate kinematics is developed based on higher order structural theory. ► The theory accounts for the realistic variation of the displacements through the thickness. ► Effect of various parameters on global response is numerically studied.
A new organic ligand, 5-(carboxyformamido)isophthalic acid (5-CFIA), was prepared and employed for the synthesis of two compounds M
(C
H
O
N
)
(8H
O)·H
O (M = Cd, Mn). The compounds have ...three-dimensionally extended structures. Both the compounds were found to be luminescent at room temperature. The luminescence nature was exploited for the detection of Hg
ions in an aqueous medium with good selectivity. The interactions between Hg
ions and the compounds quench the luminescence intensity and act as a turn-off sensor. Both the compounds exhibited low limits for the detection of Hg
ions and in the range mandated by the WHO. The interactions between Hg
ions and the compound involve the -NH group, which was probed using Raman and IR spectroscopic techniques. These studies provide important pointers toward the mechanism of this turn-off luminescence behavior. The compounds were explored for base-catalyzed aldol condensation and Lewis acid-promoted β-enaminoester formation reactions. The aldol condensation reaction uses the -NH functionality as a base. The studies indicate that the electron-withdrawing group produces products with higher yields. The β-enaminoester reaction uses the Lewis acid centers, and the studies reveal that the electron-withdrawing groups produce lesser yields of the products. The catalytic nature of the reaction and recyclability of the catalysts were also established. The catalytic reactions employ ethanol (aldol condensation) and no solvent (β-enaminoester), which suggests that the reactions are green and environmentally friendly. The Mn compound was observed to be anti-ferromagnetic.
Layered MAX phases are exfoliated into 2D single layers and multilayers, so‐called MXenes. Using first‐principles calculations, the formation and electronic properties of various MXene systems, M2C ...(M = Sc, Ti, V, Cr, Zr, Nb, Ta) and M2N (M = Ti, Cr, Zr) with surfaces chemically functionalized by F, OH, and O groups, are examined. Upon appropriate surface functionalization, Sc2C, Ti2C, Zr2C, and Hf2C MXenes are expected to become semiconductors. It is also derived theoretically that functionalized Cr2C and Cr2N MXenes are magnetic. Thermoelectric calculations based on the Boltzmann theory imply that semiconducting MXenes attain very large Seebeck coefficients at low temperatures.
2D, single‐layer nanostructures of transition metal carbides and nitrides, so‐called MXene, here M2C (M = Sc, Ti, V, Cr, Zr, Nb, Ta) and M2N (M = Ti, Cr, Zr), which are chemically functionalized by F, OH, and O groups, are shown to have potential applications in optoelectronic, spintronic, and thermoelectric nanodevices based on first‐principles calculations.
Buildings are amongst the world's largest energy consumers and simultaneous peaks in demand from networks of buildings can decrease electricity system stability. Current mitigation measures either ...entail wasteful supply-side over-specification or complex centralised demand-side control. Hence, a simple schema is developed for decentralised, self-organising building-to-building load coordination that requires very little information exchange and no top-down management-analogous to other complex systems with short range interactions, such as coordination between flocks of birds or synchronisation in fireflies. Numerical and experimental results reveal that a high degree of peak flattening can be achieved using surprisingly small load-coordination networks. The optimum reductions achieved by the simple schema can outperform existing techniques, giving substantial peak-reductions as well as being remarkably robust to changes in other system parameters such as the interaction network topology. This not only demonstrates that significant reductions in network peaks are achievable using remarkably simple control systems but also reveals interesting theoretical results and new insights which will be of great interest to the complexity and network science communities.
•The proposed model is a free form, open ended and knowledge aware VQA model.•VQA modeled as an explainable, end to end factoid question answering problem.•Model capable of leveraging granular ...details, correlate inter-related details in scenes.•Model capable of leveraging external world knowledge to answer questions.•Model capable of predicting likely explanations to justify the predicted answers.
With recent advancements in machine perception and scene understanding, Visual Question Answering (VQA) has garnered much attraction from researchers in the direction of training neural models for jointly analyzing, grounding and reasoning over the multi-modal space of image visual context and natural language in order to answer natural language questions pertaining to the image contents. However, though recent works have achieved significant improvement over state-of-art models for answering questions that are answerable by solely referring to the visual context of the image, such models are often limited, being incapable of tackling questions involving external world knowledge beyond the visible contents. Though recently, research has been driven towards tackling external knowledge based VQA as well, there is significant room for improvement as limited studies exist in this area.
Inspired by the aforementioned challenges involved, this paper is aimed at answering free form and open ended natural language questions, not limited to visual context of an image, but external world knowledge as well. With this motive, inspired by human cognitive abilities of comprehending and reasoning answers when given a set of facts, this paper proposes a novel model architecture to model VQA as a factoid question answering problem, leveraging state-of-the-art deep learning techniques for reasoning and inferring answers to free form questions, in an attempt of improving the state-of-art in open ended visual question answering.
•Propose an adaptive phase field method for quasi-static brittle fracture.•Adaptive refinement based on combination of recovery type error indicator and a quadtree decomposition.•Hanging nodes due to ...quadtree decomposition are treated within the framework of the polygonal finite element method.•Proposed framework yields comparable results with fewer degrees of freedom when compared to standard approaches.
An adaptive phase field method is proposed for crack propagation in brittle materials under quasi-static loading. The adaptive refinement is based on the recovery type error indicator, which is combined with the quadtree decomposition. Such a decomposition leads to elements with hanging nodes. Thanks to the polygonal finite element method, the elements with hanging nodes are treated as polygonal elements and hence do not require any special treatment. The mean value coordinates are used to approximate the unknown field variables and a staggered solution scheme is adopted to compute the displacement and the evolution of the phase field variable. A few standard benchmark problems are solved to show the efficiency of the proposed framework. It is seen that the proposed framework yields comparable results at a fraction of the computational cost when compared to standard approaches reported in the literature.
The paper presents a novel approach for multi-frequency acoustic topology optimization of sound-absorption materials. In this work, the isogeometric boundary element method based on subdivision ...surfaces is used to solve Helmholtz equations. To avoid time-consuming frequency sweep, we adopt a series expansion method to decouple the frequency-dependent terms from the integrand in the boundary element method, including the terms associated with the impedance boundary conditions that were introduced to model the absorption materials. Moreover, the second-order Arnoldi (SOAR) approach is employed to reduce the order of the systems. Three dimensional numerical examples were given to demonstrate the effectiveness of the proposed algorithm.
•Series expansions are utilized for frequency decoupling of acoustic BEM.•The model order is reduced by the second-order Arnoldi (SOAR) algorithm.•The isogeometric BEM is employed to integrate CAD and numerical analysis.•Multi-frequency topology optimization is performed with the isogeometric BEM.
Amongst the available methods to model fracture processes, the phase field approach has proved to be efficient and has received extensive attention. However, the approach is computationally demanding ...as it requires a very high resolution, both in space and time to resolve the fracture characteristics. In this paper, a novel adaptive phase field method is proposed for modelling quasi-static crack propagation in brittle materials. The adaptive refinement is based on the stability analysis which is combined with the quadtree decomposition. The stability analysis is based on a linear perturbation method that is used herein to determine the onset of fracture initiation on the fly. Three standard benchmark problems are solved to show the efficiency and the robustness of the proposed method. It is shown that the proposed framework does not require any post processing technique for adaptive refinement and yet is effective.
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•A new criteria is proposed for adaptive mesh refinement of phase field fracture methods.•The adaptive refinement is based on stability analysis combined with the quadtree decomposition.•A linear perturbation method is employed to determine the onset of fracture initiation on the fly.•Three benchmark fracture propagation examples verify the refinement approach and its efficiency.•The method does not require any post processing technique for refinement and yet is accurate.
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