305 research outputs found
Hierarchical temperature imaging using pseudoinversed convolutional neural network aided TDLAS tomography
As an in situ combustion diagnostic tool, Tunable Diode Laser Absorption
Spectroscopy (TDLAS) tomography has been widely used for imaging of
two-dimensional temperature distributions in reactive flows. Compared with the
computational tomographic algorithms, Convolutional Neural Networks (CNNs) have
been proofed to be more robust and accurate for image reconstruction,
particularly in case of limited access of laser beams in the Region of Interest
(RoI). In practice, flame in the RoI that requires to be reconstructed with
good spatial resolution is commonly surrounded by low-temperature background.
Although the background is not of high interest, spectroscopic absorption still
exists due to heat dissipation and gas convection. Therefore, we propose a
Pseudo-Inversed CNN (PI-CNN) for hierarchical temperature imaging that (a) uses
efficiently the training and learning resources for temperature imaging in the
RoI with good spatial resolution, and (b) reconstructs the less spatially
resolved background temperature by adequately addressing the integrity of the
spectroscopic absorption model. In comparison with the traditional CNN, the
newly introduced pseudo inversion of the RoI sensitivity matrix is more
penetrating for revealing the inherent correlation between the projection data
and the RoI to be reconstructed, thus prioritising the temperature imaging in
the RoI with high accuracy and high computational efficiency. In this paper,
the proposed algorithm was validated by both numerical simulation and lab-scale
experiment, indicating good agreement between the phantoms and the
high-fidelity reconstructions.Comment: Submitted to IEEE Transactions on Instrumentation and Measuremen
Stabilizing Electrochemical Carbon Capture Membrane with Al\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e Thin-Film Overcoating Synthesized by Chemical Vapor Deposition
Development of high-efficiency and cost-effective carbon capture technology is a central element of our effort to battle the global warming and climate change. Here we report that the unique high-flux and high-selectivity of electrochemical silver-carbonate dual-phase membranes can be retained for an extended period of operation by overcoating the surfaces of porous silver matrix with a uniform layer of Al2O3 thin-film derived from chemical vapor deposition
CSTNet: A Dual-Branch Convolutional Network for Imaging of Reactive Flows using Chemical Species Tomography
Chemical Species Tomography (CST) has been widely used for in situ imaging of
critical parameters, e.g. species concentration and temperature, in reactive
flows. However, even with state-of-the-art computational algorithms the method
is limited due to the inherently ill-posed and rank-deficient tomographic data
inversion, and by high computational cost. These issues hinder its application
for real-time flow diagnosis. To address them, we present here a novel
CST-based convolutional neural Network (CSTNet) for high-fidelity, rapid, and
simultaneous imaging of species concentration and temperature. CSTNet
introduces a shared feature extractor that incorporates the CST measurement and
sensor layout into the learning network. In addition, a dual-branch
architecture is proposed for image reconstruction with crosstalk decoders that
automatically learn the naturally correlated distributions of species
concentration and temperature. The proposed CSTNet is validated both with
simulated datasets, and with measured data from real flames in experiments
using an industry-oriented sensor. Superior performance is found relative to
previous approaches, in terms of robustness to measurement noise and
millisecond-level computing time. This is the first time, to the best of our
knowledge, that a deep learning-based algorithm for CST has been experimentally
validated for simultaneous imaging of multiple critical parameters in reactive
flows using a low-complexity optical sensor with severely limited number of
laser beams.Comment: Submitted to IEEE Transactions on Neural Networks and Learning
System
A Novel Approach for NURBS Interpolation with Minimal Feed Rate Fluctuation Based on Improved Adams-Moulton Method
In order to reduce the feed rate fluctuation of interpolation, a novel approach for NURBS interpolation with minimal feed rate fluctuation based on improved Adams-Moulton (IAM) method is proposed. At first, the representation and calculation of NURBS curve interpolation are described. Then, the constraints of feeding step length are firstly given out to calculate the minimal hoping feeding step length and the detailed IAM method of NURBS curve interpolation is presented. Finally, simulations and experiments are carried out to verify the feasibility and applicability of proposed IAM method
Beyond Sharing: Conflict-Aware Multivariate Time Series Anomaly Detection
Massive key performance indicators (KPIs) are monitored as multivariate time
series data (MTS) to ensure the reliability of the software applications and
service system. Accurately detecting the abnormality of MTS is very critical
for subsequent fault elimination. The scarcity of anomalies and manual labeling
has led to the development of various self-supervised MTS anomaly detection
(AD) methods, which optimize an overall objective/loss encompassing all
metrics' regression objectives/losses. However, our empirical study uncovers
the prevalence of conflicts among metrics' regression objectives, causing MTS
models to grapple with different losses. This critical aspect significantly
impacts detection performance but has been overlooked in existing approaches.
To address this problem, by mimicking the design of multi-gate
mixture-of-experts (MMoE), we introduce CAD, a Conflict-aware multivariate KPI
Anomaly Detection algorithm. CAD offers an exclusive structure for each metric
to mitigate potential conflicts while fostering inter-metric promotions. Upon
thorough investigation, we find that the poor performance of vanilla MMoE
mainly comes from the input-output misalignment settings of MTS formulation and
convergence issues arising from expansive tasks. To address these challenges,
we propose a straightforward yet effective task-oriented metric selection and
p&s (personalized and shared) gating mechanism, which establishes CAD as the
first practicable multi-task learning (MTL) based MTS AD model. Evaluations on
multiple public datasets reveal that CAD obtains an average F1-score of 0.943
across three public datasets, notably outperforming state-of-the-art methods.
Our code is accessible at https://github.com/dawnvince/MTS_CAD.Comment: 11 pages, ESEC/FSE industry track 202
Volumes of hippocampal subfields suggest a continuum between schizophrenia, major depressive disorder and bipolar disorder
ObjectiveThere is considerable debate as to whether the continuum of major psychiatric disorders exists and to what extent the boundaries extend. Converging evidence suggests that alterations in hippocampal volume are a common sign in psychiatric disorders; however, there is still no consensus on the nature and extent of hippocampal atrophy in schizophrenia (SZ), major depressive disorder (MDD) and bipolar disorder (BD). The aim of this study was to verify the continuum of SZ – BD – MDD at the level of hippocampal subfield volume and to compare the volume differences in hippocampal subfields in the continuum.MethodsA total of 412 participants (204 SZ, 98 MDD, and 110 BD) underwent 3 T MRI scans, structured clinical interviews, and clinical scales. We segmented the hippocampal subfields with FreeSurfer 7.1.1 and compared subfields volumes across the three diagnostic groups by controlling for age, gender, education, and intracranial volumes.ResultsThe results showed a gradual increase in hippocampal subfield volumes from SZ to MDD to BD. Significant volume differences in the total hippocampus and 13 of 26 hippocampal subfields, including CA1, CA3, CA4, GC-ML-DG, molecular layer and the whole hippocampus, bilaterally, and parasubiculum in the right hemisphere, were observed among diagnostic groups. Medication treatment had the most effect on subfields of MDD compared to SZ and BD. Subfield volumes were negatively correlated with illness duration of MDD. Positive correlations were found between subfield volumes and drug dose in SZ and MDD. There was no significant difference in laterality between diagnostic groups.ConclusionThe pattern of hippocampal volume reduction in SZ, MDD and BD suggests that there may be a continuum of the three disorders at the hippocampal level. The hippocampus represents a phenotype that is distinct from traditional diagnostic strategies. Combined with illness duration and drug intervention, it may better reflect shared pathophysiology and mechanisms across psychiatric disorders
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