54 research outputs found
Real-time model-based control of single pass tangential flow filtration for production of monoclonal antibodies
Please click Additional Files below to see the full abstract.
Please click Download on the upper right corner to see the presentation
Balling and granulation kinetics revisited
Balling of finely comminuted solids by random coalescence and granulation of iron ore fines and other minerals by autolayering are two major size enlargement processes. The existing kinetic model for random coalescence does not take into account the strong dependence of coordination number on the size distribution of agglomerating entities. We present a coordination number based coalescence model, which mimics the underlying physical process more realistically. Simulations show that in spite of highly diverse model structures, random and coordination coalescence models give remarkably similar results. Only static models of autolayering are available presently. These map the input size distribution of feed solids into steady state or terminal size distribution of granules, with little or no information on the path traversed by the process. We propose a continuous-time dynamic model of autolayering within the population balance framework. The model, which is based on the proportionate growth postulate of autolayering, agrees reasonably well with experimental data
A population balance model for flocculation of colloidal suspensions by polymer bridging
A detailed population balance model for flocculation of colloidal suspensions by polymer bridging under quiescent flow conditions is presented. The collision efficiency factor is estimated as a function of interaction forces between polymer coated particles. The total interaction energy is computed as a sum of van der Waals attraction, electrical double layer repulsion and bridging attraction or steric repulsion due to adsorbed polymer. The scaling theory is used to compute the forces due to adsorbed polymer and the van der Waals attraction is modified to account for presence of polymer layer around a particle. The irregular structure of flocs is taken into account by incorporating the mass fractal dimension of flocs. When tested with experimental floc size distribution data published in the literature, the model predicts the experimental behavior adequately. This is the first attempt towards incorporating theories of polymer-induced surface forces into a flocculation model, and as such the model presented here is more general than those proposed previously
Redefining Super-Resolution: Fine-mesh PDE predictions without classical simulations
In Computational Fluid Dynamics (CFD), coarse mesh simulations offer
computational efficiency but often lack precision. Applying conventional
super-resolution to these simulations poses a significant challenge due to the
fundamental contrast between downsampling high-resolution images and
authentically emulating low-resolution physics. The former method conserves
more of the underlying physics, surpassing the usual constraints of real-world
scenarios. We propose a novel definition of super-resolution tailored for
PDE-based problems. Instead of simply downsampling from a high-resolution
dataset, we use coarse-grid simulated data as our input and predict fine-grid
simulated outcomes. Employing a physics-infused UNet upscaling method, we
demonstrate its efficacy across various 2D-CFD problems such as discontinuity
detection in Burger's equation, Methane combustion, and fouling in Industrial
heat exchangers. Our method enables the generation of fine-mesh solutions
bypassing traditional simulation, ensuring considerable computational saving
and fidelity to the original ground truth outcomes. Through diverse boundary
conditions during training, we further establish the robustness of our method,
paving the way for its broad applications in engineering and scientific CFD
solvers.Comment: Accepted at Machine Learning and the Physical Sciences Workshop,
NeurIPS 202
HyperLoRA for PDEs
Physics-informed neural networks (PINNs) have been widely used to develop
neural surrogates for solutions of Partial Differential Equations. A drawback
of PINNs is that they have to be retrained with every change in
initial-boundary conditions and PDE coefficients. The Hypernetwork, a
model-based meta learning technique, takes in a parameterized task embedding as
input and predicts the weights of PINN as output. Predicting weights of a
neural network however, is a high-dimensional regression problem, and
hypernetworks perform sub-optimally while predicting parameters for large base
networks. To circumvent this issue, we use a low ranked adaptation (LoRA)
formulation to decompose every layer of the base network into low-ranked
tensors and use hypernetworks to predict the low-ranked tensors. Despite the
reduced dimensionality of the resulting weight-regression problem, LoRA-based
Hypernetworks violate the underlying physics of the given task. We demonstrate
that the generalization capabilities of LoRA-based hypernetworks drastically
improve when trained with an additional physics-informed loss component
(HyperPINN) to satisfy the governing differential equations. We observe that
LoRA-based HyperPINN training allows us to learn fast solutions for
parameterized PDEs like Burger's equation and Navier Stokes: Kovasznay flow,
while having an 8x reduction in prediction parameters on average without
compromising on accuracy when compared to all other baselines.Comment: 8 pages, 4 figures, 3 Table
Ensemble Deep Learning for Detecting Onset of Abnormal Operation in Industrial Multi-component Systems
Breakdowns and unplanned shutdowns in industrial
processes and equipment can lead to significant loss of
availability and revenue. It is imperative to perform optimal
maintenance of such systems when signs of abnormal
behavior are detected and before they propagate and lead to
catastrophic failure. This is particularly challenging in
systems with interconnected multiple components as it is
difficult to isolate the effect of one component on the
operation of other components in the system. In this work,
an ensemble approach based on Cascaded Convolutional
neural network and Long Short-term Memory (CC-LSTM)
network models is proposed for detecting and predicting the
time of onset of faults in interconnected multicomponent
systems. The performance of the ensemble CC-LSTM
model was demonstrated on an industrial 4-component
system and was found to improve the accuracy of onset time
predictions by ~15% compared to individual CC-LSTM
models and ~25-40% compared to commonly used deep
learning techniques such as dense neural networks,
convolutional neural networks and LSTMs. The CC-LSTM
and the ensemble models also had the lowest missed
detection rates and zero false positive rates making them
ideal for real-time monitoring and fault detection in
multicomponent systems
Data for: A Coupled CFD-PBM and Thermodynamic Analysis of Continuous Supercritical Hydrothermal Synthesis of Nanoparticles
We have provided the detailed boundary conditions for all the variables, model parameters, and user-defined functions for mass averaged density, nucleation rate, diffusional growth rate, and coagulation kernels etc
Thermodynamic analysis of hydrothermal synthesis of nanoparticles
The hydrothermal method is one of the most commonly employed techniques for synthesis of metal oxides, metals, and metal composites with different crystalline structures and morphologies, that are in the form of fine particles. The hydrothermal synthesis of nanoparticles involves hydrolysis of metal salt and condensation of metal hydroxide to produce ultrafine metal or metal oxide particles. We propose a Thermodynamic Modeling Framework for predicting the stability of the chemical species under the hydrothermal conditions. This can help in identifying the feasible regions for the hydrothermal synthesis of materials. The method is based on the integration of the Gibbs free energy equation, modified Bromley model for predicting activity coefficients, and the revised Helgeson-Kirkham-Flowers (HKF) model for estimating the standard-state thermodynamic properties of the species. The framework is tested with published experimental data for the synthesis of boehmite under subcritical temperature and supercritical conditions. The stability diagrams are generated for ceria and boehmite. The effect of pressure on the stability of the ceria species is studied. The proposed thermodynamic framework is useful for determining and identifying the process conditions under which the metal complex of interest is thermodynamically stable. (C) 2017 Elsevier B.V. All rights reserved
Mathematical modeling of polymer-induced flocculation by charge neutralization
A detailed mathematical model for flocculation of colloidal suspensions in presence of salts and polymers is described and validated. In former case, the classical DLVO theory, which accounts for relevant variables such as pH and salt concentration, is incorporated into a geometrically sectioned discrete population balance model. For processes involving polymers, flocculation via simple charge neutralization is modeled using a modified DLVO theory in which the effect of adsorbed polymer layers on van der Waals attraction is included. The fractal dimension of aggregates is obtained by dynamic scaling of experimental data for time evolution of mean aggregate size. The particle surface potential is assumed to be approximately equal to the zeta potential. The model predictions are in close agreement with experimental results for flocculation of colloidal hematite suspensions in the presence of KCl and polyacrylic acid at different concentrations. In particular, given values of model parameters, e.g., Hamaker constant, fractal dimension, surface potential, and thickness of adsorbed polymer layer, the model can realistically describe the kinetics of flocculation by a simple charge neutralization mechanism and track the evolution of floc size distribution. Representative examples of sensitivity of the flocculation model to perturbations in surface potential and fractal dimension and to modification in the DLVO theory for polymer-coated particles are included
- …