339 research outputs found
Deep spectral learning for label-free optical imaging oximetry with uncertainty quantification
Measurement of blood oxygen saturation (sO2) by optical imaging oximetry provides invaluable insight into local tissue functions and metabolism. Despite different embodiments and modalities, all label-free optical-imaging oximetry techniques utilize the same principle of sO2-dependent spectral contrast from haemoglobin. Traditional approaches for quantifying sO2 often rely on analytical models that are fitted by the spectral measurements. These approaches in practice suffer from uncertainties due to biological variability, tissue geometry, light scattering, systemic spectral bias, and variations in the experimental conditions. Here, we propose a new data-driven approach, termed deep spectral learning (DSL), to achieve oximetry that is highly robust to experimental variations and, more importantly, able to provide uncertainty quantification for each sO2 prediction. To demonstrate the robustness and generalizability of DSL, we analyse data from two visible light optical coherence tomography (vis-OCT) setups across two separate in vivo experiments on rat retinas. Predictions made by DSL are highly adaptive to experimental variabilities as well as the depth-dependent backscattering spectra. Two neural-network-based models are tested and compared with the traditional least-squares fitting (LSF) method. The DSL-predicted sO2 shows significantly lower mean-square errors than those of the LSF. For the first time, we have demonstrated en face maps of retinal oximetry along with a pixel-wise confidence assessment. Our DSL overcomes several limitations of traditional approaches and provides a more flexible, robust, and reliable deep learning approach for in vivo non-invasive label-free optical oximetry.R01 CA224911 - NCI NIH HHS; R01 CA232015 - NCI NIH HHS; R01 NS108464 - NINDS NIH HHS; R21 EY029412 - NEI NIH HHSAccepted manuscrip
EFFECTS OF DRIVERLESS VEHICLES ON THE COMPETITIVENESS OF BUS TRANSIT SERVICES
The advent of driverless vehicles, including automobiles and buses, may considerably affect the competitiveness and ridership of public transportation services in negative as well as positive ways. Since driverless vehicles may be widely used in the fairly near future, public transit operators and transportation planners should prepare to deal with their anticipated effects. In this thesis the author (1) formulate modular optimization models for both human-driven and automated bus services with fixed routes as well as flexible routes, (2) develop preliminary quantitative assessments of those effects, showing that without drivers, competitiveness of public transportation compared to private transportation decreases; (3) conduct sensitivity analyses to explore how changes in input parameters affect the results; and (4) identify insights in which transit operators, transportation planners and other transportation system stakeholders may use in effectively adapting to the introduction of driverless vehicles
Recurrent neural networks model based reliability assessment of power semiconductors in PMSG converter
DyCL: Dynamic Neural Network Compilation Via Program Rewriting and Graph Optimization
DL compiler's primary function is to translate DNN programs written in
high-level DL frameworks such as PyTorch and TensorFlow into portable
executables. These executables can then be flexibly executed by the deployed
host programs. However, existing DL compilers rely on a tracing mechanism,
which involves feeding a runtime input to a neural network program and tracing
the program execution paths to generate the computational graph necessary for
compilation. Unfortunately, this mechanism falls short when dealing with modern
dynamic neural networks (DyNNs) that possess varying computational graphs
depending on the inputs. Consequently, conventional DL compilers struggle to
accurately compile DyNNs into executable code. To address this limitation, we
propose \tool, a general approach that enables any existing DL compiler to
successfully compile DyNNs. \tool tackles the dynamic nature of DyNNs by
introducing a compilation mechanism that redistributes the control and data
flow of the original DNN programs during the compilation process. Specifically,
\tool develops program analysis and program transformation techniques to
convert a dynamic neural network into multiple sub-neural networks. Each
sub-neural network is devoid of conditional statements and is compiled
independently. Furthermore, \tool synthesizes a host module that models the
control flow of the DyNNs and facilitates the invocation of the sub-neural
networks. Our evaluation demonstrates the effectiveness of \tool, achieving a
100\% success rate in compiling all dynamic neural networks. Moreover, the
compiled executables generated by \tool exhibit significantly improved
performance, running between and faster than the
original DyNNs executed on general-purpose DL frameworks.Comment: This paper has been accepted to ISSTA 202
Flexible coherent control of plasmonic spin-Hall effect
The surface plasmon polariton is an emerging candidate for miniaturizing optoelectronic circuits. Recent demonstrations of polarization-dependent splitting using metasurfaces, including focal-spot shifting and unidirectional propagation, allow us to exploit the spin degree of freedom in plasmonics. However, further progress has been hampered by the inability to generate more complicated and independent surface plasmon profiles for two incident spins, which work coherently together for more flexible and tunable functionalities. Here by matching the geometric phases of the nano-slots on silver to specific superimpositions of the inward and outward surface plasmon profiles for the two spins, arbitrary spin-dependent orbitals can be generated in a slot-free region. Furthermore, motion pictures with a series of picture frames can be assembled and played by varying the linear polarization angle of incident light. This spin-enabled control of orbitals is potentially useful for tip-free near-field scanning microscopy, holographic data storage, tunable plasmonic tweezers, and integrated optical components
Once is Enough: A Light-Weight Cross-Attention for Fast Sentence Pair Modeling
Transformer-based models have achieved great success on sentence pair
modeling tasks, such as answer selection and natural language inference (NLI).
These models generally perform cross-attention over input pairs, leading to
prohibitive computational costs. Recent studies propose dual-encoder and late
interaction architectures for faster computation. However, the balance between
the expressive of cross-attention and computation speedup still needs better
coordinated. To this end, this paper introduces a novel paradigm MixEncoder for
efficient sentence pair modeling. MixEncoder involves a light-weight
cross-attention mechanism. It conducts query encoding only once while modeling
the query-candidate interaction in parallel. Extensive experiments conducted on
four tasks demonstrate that our MixEncoder can speed up sentence pairing by
over 113x while achieving comparable performance as the more expensive
cross-attention models.Comment: Accepted to EMNLP 202
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