266 research outputs found
A Bayesian framework for discovering interpretable Lagrangian of dynamical systems from data
Learning and predicting the dynamics of physical systems requires a profound
understanding of the underlying physical laws. Recent works on learning
physical laws involve generalizing the equation discovery frameworks to the
discovery of Hamiltonian and Lagrangian of physical systems. While the existing
methods parameterize the Lagrangian using neural networks, we propose an
alternate framework for learning interpretable Lagrangian descriptions of
physical systems from limited data using the sparse Bayesian approach. Unlike
existing neural network-based approaches, the proposed approach (a) yields an
interpretable description of Lagrangian, (b) exploits Bayesian learning to
quantify the epistemic uncertainty due to limited data, (c) automates the
distillation of Hamiltonian from the learned Lagrangian using Legendre
transformation, and (d) provides ordinary (ODE) and partial differential
equation (PDE) based descriptions of the observed systems. Six different
examples involving both discrete and continuous system illustrates the efficacy
of the proposed approach
A foundational neural operator that continuously learns without forgetting
Machine learning has witnessed substantial growth, leading to the development
of advanced artificial intelligence models crafted to address a wide range of
real-world challenges spanning various domains, such as computer vision,
natural language processing, and scientific computing. Nevertheless, the
creation of custom models for each new task remains a resource-intensive
undertaking, demanding considerable computational time and memory resources. In
this study, we introduce the concept of the Neural Combinatorial Wavelet Neural
Operator (NCWNO) as a foundational model for scientific computing. This model
is specifically designed to excel in learning from a diverse spectrum of
physics and continuously adapt to the solution operators associated with
parametric partial differential equations (PDEs). The NCWNO leverages a gated
structure that employs local wavelet experts to acquire shared features across
multiple physical systems, complemented by a memory-based ensembling approach
among these local wavelet experts. This combination enables rapid adaptation to
new challenges. The proposed foundational model offers two key advantages: (i)
it can simultaneously learn solution operators for multiple parametric PDEs,
and (ii) it can swiftly generalize to new parametric PDEs with minimal
fine-tuning. The proposed NCWNO is the first foundational operator learning
algorithm distinguished by its (i) robustness against catastrophic forgetting,
(ii) the maintenance of positive transfer for new parametric PDEs, and (iii)
the facilitation of knowledge transfer across dissimilar tasks. Through an
extensive set of benchmark examples, we demonstrate that the NCWNO can
outperform task-specific baseline operator learning frameworks with minimal
hyperparameter tuning at the prediction stage. We also show that with minimal
fine-tuning, the NCWNO performs accurate combinatorial learning of new
parametric PDEs
Mg-MOF-74@SBA-15 hybrids: synthesis, characterization, and adsorption properties
Nanocrystals of Mg-MOF-74 have been immobilized into the mesopores of SBA-15 rods to fabricate Mg-MOF-74@SBA-15 hybrid materials. To furnish such composites, a relatively simple synthetic strategy has been adopted by direct dispersion of the metal-organic framework (MOF) precursors in SBA-15 matrix to prepare the hybrid materials in situ. The hybrid materials have been characterized using powder X-ray diffraction and several spectroscopic and microscopic techniques, which suggest growth of the MOF nanocrystals inside the SBA-15 mesopores and the composites exhibit characteristics of both the components. N2 adsorption isotherms at 77 K reveal that the composites contain additional mesopores, compared to only micropores of pristine MOF nanocrystals. In addition to such combination of both micro and mesoporosity, the composites also demonstrate significant CO2 adsorption at room temperature
Structural diversities in metal-organic coordination polymers based on flexibility in organic spacer
Metal-organic coordination polymers with their various novel structural motifs have drawn intense research interests over the last few decades. Interestingly, flexibility of the organic spacers in such metalorganic coordination polymers can direct various structural topology and intricate networks. A novel 1D coordination polymer and some other illustrative examples with different flexible ligands like 1,2-bis(4-pyridyl)ethane (bpe) and 1,3-bis(4-pyridyl)propane (bpp) have been discussed in this review. Both gauche and anti-conformations could be adopted by the bpe ligand, and hence diverse structures can be furnished. Further flexibility could be achieved by exploiting longer ligand like 1,3-bis(4-pyridyl) propane (bpp). Our group has been pursuing research to furnish such flexible compounds and study their different functionalities. An account of design of such diverse systems by employing judicious ligand design strategy and their different structural aspects will be presented in this review
Multi-fidelity wavelet neural operator with application to uncertainty quantification
Operator learning frameworks, because of their ability to learn nonlinear
maps between two infinite dimensional functional spaces and utilization of
neural networks in doing so, have recently emerged as one of the more pertinent
areas in the field of applied machine learning. Although these frameworks are
extremely capable when it comes to modeling complex phenomena, they require an
extensive amount of data for successful training which is often not available
or is too expensive. However, this issue can be alleviated with the use of
multi-fidelity learning, where a model is trained by making use of a large
amount of inexpensive low-fidelity data along with a small amount of expensive
high-fidelity data. To this end, we develop a new framework based on the
wavelet neural operator which is capable of learning from a multi-fidelity
dataset. The developed model's excellent learning capabilities are demonstrated
by solving different problems which require effective correlation learning
between the two fidelities for surrogate construction. Furthermore, we also
assess the application of the developed framework for uncertainty
quantification. The results obtained from this work illustrate the excellent
performance of the proposed framework
Applied Molecular Cloning: Present and Future for Aquaculture
With the grim picture of millions of people living in poverty and hunger, there is also an international alarm over future world food supply. This global concern of food scarcity has established the need to not only increase the production of traditional staples but also fisheries and aquaculture. Genetically, physiologically and phenotypically, fish are the most diverse group of livings. Similar to mammals, molecular biology is being extensively used in aquaculture, be it in disease management, or growth and reproduction enhancement. In this chapter we aim to discuss the molecular methodologies applied to uplift and attain sustainability in aqua farming
Laser-induced fluorescence spectroscopy in supersonic jet and large amplitude motion
Combining supersonic jet techniques with tunable lasers, scientists have been able to obtain precise
information on the static and dynamic properties of the molecules in their ground and excited states. The principle of the jet spectroscopies along with application of laser-induced fluorescence technique to large amplitude-vibrational motion has been discussed
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