Energy
Authentication of Underwater Assets
Téglásy, Bálint Z., Wengle, Emil, Potter, John R., Katsikas, Sokratis
Secure digital wireless communication underwater has become a key issue as maritime operations shift towards employing a heterogeneous mix of robotic assets and as the security of digital systems becomes challenged across all domains. At the same time, a proliferation of underwater signal coding and physical layer options are delivering greater bandwidth and flexibility, but mostly without the standards necessary for interoperability. We address here an essential requirement for security, namely a confirmation of asset identities also known as authentication. We propose, implement, verify and validate an authentication protocol based on the first digital underwater communications standard. Our scheme is applicable primarily to AUVs operating around offshore oil and gas facilities, but also to other underwater devices that may in the future have acoustic modems. It makes communication including command and control significantly more secure and provides a foundation for the development of more sophisticated security mechanisms.
Advancing Reacting Flow Simulations with Data-Driven Models
Zdybał, Kamila, D'Alessio, Giuseppe, Aversano, Gianmarco, Malik, Mohammad Rafi, Coussement, Axel, Sutherland, James C., Parente, Alessandro
The use of machine learning algorithms to predict behaviors of complex systems is booming. However, the key to an effective use of machine learning tools in multi-physics problems, including combustion, is to couple them to physical and computer models. The performance of these tools is enhanced if all the prior knowledge and the physical constraints are embodied. In other words, the scientific method must be adapted to bring machine learning into the picture, and make the best use of the massive amount of data we have produced, thanks to the advances in numerical computing. The present chapter reviews some of the open opportunities for the application of data-driven reduced-order modeling of combustion systems. Examples of feature extraction in turbulent combustion data, empirical low-dimensional manifold (ELDM) identification, classification, regression, and reduced-order modeling are provided.
A variational neural network approach for glacier modelling with nonlinear rheology
Cui, Tiangang, Wang, Zhongjian, Zhang, Zhiwen
In this paper, we propose a mesh-free method to solve full stokes equation which models the glacier movement with nonlinear rheology. Our approach is inspired by the Deep-Ritz method proposed in [12]. We first formulate the solution of non-Newtonian ice flow model into the minimizer of a variational integral with boundary constraints. The solution is then approximated by a deep neural network whose loss function is the variational integral plus soft constraint from the mixed boundary conditions. Instead of introducing mesh grids or basis functions to evaluate the loss function, our method only requires uniform samplers of the domain and boundaries. To address instability in real-world scaling, we re-normalize the input of the network at the first layer and balance the regularizing factors for each individual boundary. Finally, we illustrate the performance of our method by several numerical experiments, including a 2D model with analytical solution, Arolla glacier model with real scaling and a 3D model with periodic boundary conditions. Numerical results show that our proposed method is efficient in solving the non-Newtonian mechanics arising from glacier modeling with nonlinear rheology.
A Robust Learning Methodology for Uncertainty-aware Scientific Machine Learning models
Almeida, Erbet Costa, Rebello, Carine de Menezes, Fontana, Marcio, Schnitman, Leizer, Nogueira, Idelfonso Bessa dos Reis
Robust learning is an important issue in Scientific Machine Learning (SciML). There are several works in the literature addressing this topic. However, there is an increasing demand for methods that can simultaneously consider all the different uncertainty components involved in SciML model identification. Hence, this work proposes a comprehensive methodology for uncertainty evaluation of the SciML that also considers several possible sources of uncertainties involved in the identification process. The uncertainties considered in the proposed method are the absence of theory and causal models, the sensitiveness to data corruption or imperfection, and the computational effort. Therefore, it was possible to provide an overall strategy for the uncertainty-aware models in the SciML field. The methodology is validated through a case study, developing a Soft Sensor for a polymerization reactor. The results demonstrated that the identified Soft Sensor are robust for uncertainties, corroborating with the consistency of the proposed approach.
Ensemble of Pre-Trained Neural Networks for Segmentation and Quality Detection of Transmission Electron Microscopy Images
Baskaran, Arun, Lin, Yulin, Wen, Jianguo, Chan, Maria K. Y.
Automated analysis of electron microscopy datasets poses multiple challenges, such as limitation in the size of the training dataset, variation in data distribution induced by variation in sample quality and experiment conditions, etc. It is crucial for the trained model to continue to provide acceptable segmentation/classification performance on new data, and quantify the uncertainty associated with its predictions. Among the broad applications of machine learning, various approaches have been adopted to quantify uncertainty, such as Bayesian modeling, Monte Carlo dropout, ensembles, etc. With the aim of addressing the challenges specific to the data domain of electron microscopy, two different types of ensembles of pre-trained neural networks were implemented in this work. The ensembles performed semantic segmentation of ice crystal within a two-phase mixture, thereby tracking its phase transformation to water. The first ensemble (EA) is composed of U-net style networks having different underlying architectures, whereas the second series of ensembles (ER-i) are composed of randomly initialized U-net style networks, wherein each base learner has the same underlying architecture 'i'. The encoders of the base learners were pre-trained on the Imagenet dataset. The performance of EA and ER were evaluated on three different metrics: accuracy, calibration, and uncertainty. It is seen that EA exhibits a greater classification accuracy and is better calibrated, as compared to ER. While the uncertainty quantification of these two types of ensembles are comparable, the uncertainty scores exhibited by ER were found to be dependent on the specific architecture of its base member ('i') and not consistently better than EA. Thus, the challenges posed for the analysis of electron microscopy datasets appear to be better addressed by an ensemble design like EA, as compared to an ensemble design like ER.
Data-driven Reference Trajectory Optimization for Precision Motion Systems
Balula, Samuel, Liao-McPherson, Dominic, Rupenyan, Alisa, Lygeros, John
We propose a data-driven optimization-based pre-compensation method to improve the contour tracking performance of precision motion stages by modifying the reference trajectory and without modifying any built-in low-level controllers. The position of the precision motion stage is predicted with data-driven models, a linear low-fidelity model is used to optimize traversal time, by changing the path velocity and acceleration profiles then a non-linear high-fidelity model is used to refine the previously found time-optimal solution. We experimentally demonstrate that the proposed method is capable of simultaneously improving the productivity and accuracy of a high precision motion stage. Given the data-based nature of the models, the proposed method can easily be adapted to a wide family of precision motion systems.
Artificial Intelligence Methods for Fault Diagnosis in Centrifugal Pumps
Maamar Ali Saud Al Tobi, Ph.D., is Assistant Professor and Deputy Head of the Mechanical and Industrial Engineering Department at the National University of Science and Technology, Muscat, Oman. His teaching and research areas include machine condition monitoring, vibration analysis, artificial intelligence, genetic algorithm, and maintenance management and strategies. He is author of numerous papers in international journals on fault diagnosis in rotating machinery using AI systems. Geraint Bevan, Ph.D., is Senior Lecturer in Applied Instrumentation and Control at the School of Computing, Engineering and Built Environment at Glasgow Caledonian University, Glasgow, Scotland. He is widely published on bond-graph modeling for control system design, design of automotive control systems, monitoring for nuclear safeguards, machine condition monitoring, and renewable energy.
Soaking up the sun with artificial intelligence
It will be doing so for billions more years. Yet, we have only just begun tapping into that abundant, renewable source of energy at affordable cost. Solar absorbers are a material used to convert this energy into heat or electricity. Maria Chan, a scientist in the U.S. Department of Energy's (DOE) Argonne National Laboratory, has developed a machine learning method for screening many thousands of compounds as solar absorbers. Her co-author on this project was Arun Mannodi-Kanakkithodi, a former Argonne postdoc who is now an assistant professor at Purdue University.
Model Predictive Control Design of a 3-DOF Robot Arm Based on Recognition of Spatial Coordinates
Zhou, Zhangxi, Zhang, Yuyao, Li, Yezhang
This paper uses Model Predictive Control (MPC) to optimise the input torques of a Three-Degrees-of-Freedom (DOF) robotic arm, enabling it to operate to the target position and grasp the object accurately. A monocular camera is firstly used to recognise the colour and depth of the object. Then, the inverse kinematics calculation and the spatial coordinates of the object through coordinate transformation are combined to get the required rotating angle of each servo. Finally, the dynamic model of the robotic arm structure is derived and the model predictive control is applied to simulate the optimal input torques of servos to minimize the cost function.
This Week's Awesome Tech Stories From Around the Web (Through Sept 3)
An AI-generated Artwork's State Fair Victory Fuels Arguments Over'What Art Is' James Vincent The Verge "The rise of text-to-AI image generators has only just begun, but already, the programs are sparking heated debates about the nature of art, whether this software poses a threat to artists' livelihoods, and whether or not the companies that create these systems [owe] anything to the artists whose work their programs are trained on." A New Gene Therapy Based on Antibody Cells Is About to Be Tested in Humans Antonio Regalado MIT Technology Review "The concept is to engineer B cells so that they manufacture other proteins instead of antibodies. For [the rare inherited disease MPS-1], what's needed is an enzyme whose absence causes diverse and devastating symptoms. Patients with the illness are currently treated with weekly infusions of the missing enzyme, but it's not enough to cure the disease outright. Immusoft says it can engineer B cells to produce the enzyme instead."