| 1. |
- Feng, Yifan, et al.
(author)
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Fractal Superconducting Nanowire Single-Photon Detectors and Their Applications in Imaging
- 2022
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In: Proceedings of the 2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO/PR 2022. - : Optica Publishing Group.
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Conference paper (peer-reviewed)abstract
- We present our research on fractal superconducting nanowire single-photon detectors and their applications in light detection and ranging (LiDAR), full-Stokes polarimetric imaging, and non-line-of-sight imaging.
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| 2. |
- Feng, Yifan, et al.
(author)
-
Fractal Superconducting Nanowire Single-Photon Detectors and Their Applications in Imaging
- 2022
-
In: 2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2022 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc..
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Conference paper (peer-reviewed)abstract
- We present our research on fractal superconducting nanowire single-photon detectors and their applications in light detection and ranging (LiDAR), full-Stokes polarimetric imaging, and non-line-of-sight imaging.
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| 3. |
- Hu, Nan, et al.
(author)
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Full-Stokes polarimetric measurements and imaging using a fractal superconducting nanowire single-photon detector
- 2022
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In: Optica. - : Optica Publishing Group. - 2334-2536. ; 9:4, s. 346-351
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Journal article (peer-reviewed)abstract
- Measuring the states of polarization (SoP) of light is fundamentally important for applications ranging from communication, sensing, spectroscopy, imaging, to navigation. Superconducting nanowire single-photon detectors (SNSPDs) are ideal detectors of choice for faint-light detection and measurements, but SNSPDs themselves cannot resolve the SoP of photons. Here, based on a fractal SNSPD, we demonstrate a full-Stokes polarimetric measurement system that can measure arbitrary SoP of faint light. The measured SoPs are in excellent agreement with those of a state-of-the-art commercial polarimeter, but the sensitivity of our system reaches -86.6 dBm, which is 26.6 dB better than that of the commercial counterpart. As a direct application, we further demonstrate remote polarimetric imaging (i.e., polarimetric LiDAR) with a complete set of polarimetric contrast.
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| 4. |
- Hu, N., et al.
(author)
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Polarimetric Imaging Using One Fractal SNSPD
- 2022
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In: 2022 Conference on Lasers and Electro-Optics, CLEO 2022. - : Institute of Electrical and Electronics Engineers Inc..
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Conference paper (peer-reviewed)abstract
- We demonstrate a polarimetric imaging system with one fractal superconducting nanowire single-photon detector and time-multiplexed photon-counting scheme, which allows us to obtain images with multiple types of contrast.
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| 5. |
- Meng, Yun, et al.
(author)
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Fractal Superconducting Nanowires Detect Infrared Single Photonswith 84% System Detection Efficiency, 1.02 Polarization Sensitivity,and 20.8 ps Timing Resolution br
- 2022
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In: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 9:5, s. 1547-1553
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Journal article (peer-reviewed)abstract
- The near-unity system detection efficiency (SDE) and excellent timing resolution of superconducting nanowiresingle-photon detectors (SNSPDs), combined with their other merits, have enabled many classical and quantum photonicapplications. However, the prevalent design based on meandering nanowires makes SDE dependent on the polarization states of theincident photons; for unpolarized light, the major merit of high SDE would get compromised, which could be detrimental to photon-starved applications. Here, we create SNSPDs with an arced fractal geometry that almost completely eliminates this polarizationdependence of the SDE, and we experimentally demonstrate 84 +/- 3% SDE, 1.02-0.02+0.06polarization sensitivity at the wavelength of1575 nm, and 20.8 ps timing jitter in a 0.1 W closed-cycle Gifford-McMahon cryocooler, at the base temperature of 2.0 K. Thisdemonstration provides a novel, practical device structure of SNSPDs, allowing for operation in the visible, near-infrared, and mid-infrared spectral ranges, and paves the way for polarization-insensitive single-photon detection with high SDE and high timingresolution.
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| 6. |
- Zou, Kai, et al.
(author)
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Superconducting Nanowire Single-Photon Detectors and Multi-Photon Detectors
- 2022
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In: Optics InfoBase Conference Papers. - : Optica Publishing Group (formerly OSA).
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Conference paper (peer-reviewed)abstract
- We present our research progress in superconducting nanowire single-photon detectors (SNSPDs) and multi-photon detectors (SNMPDs), including fractal SNSPDs with reduced polarization sensitivity, two mechanisms of device timing jitter, and SNMPDs integrated with current reservoirs.
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| 7. |
- Feng, Junyi, et al.
(author)
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Aggregation-Induced Emission in a Polymeric Photovoltaic Donor Material
- 2022
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In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 126:48, s. 20275-20283
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Journal article (peer-reviewed)abstract
- In this work, we report the aggregation-induced emission in a polymeric donor material poly(bis(2-butyloctyl)[2,2′:5′,2″-terthiophene]-4,4″-dicarboxylate-5,5′-diyl-vinylene) (PTVT-T), which exhibits a high device performance for the application of photovoltaics. Time-dependent density functional theory calculations and steady-state and time-resolved spectroscopy have been employed to reveal the underlying emission mechanism. We find that the aggregation of the PTVT-T polymer chain in solution increases the exciton luminescence lifetime and exciton emission quantum yield, which is related to the effective torsional inhibition of carbon-carbon single bonds. Compared with the aggregates in solution, the exciton emission quantum yield of the aggregates in PTVT-T film is reduced. It is attributable to exciton delocalization caused by the improvement of molecular planarity in film. We also observe that the as-cast film and thermally annealed film show distinctly different emission behaviors. This work can shed light on designing optoelectronic polymer materials with the integration of photovoltaic and light-emitting functions.
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| 8. |
- Hu, Lin, et al.
(author)
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A study on energy distribution strategy of electric vehicle hybrid energy storage system considering driving style based on real urban driving data
- 2022
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In: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 162
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Journal article (peer-reviewed)abstract
- This paper proposes a novel energy distribution optimization method of hybrid energy storage system (HESS) and its improved semi-active topology for electric vehicles (EVs) to further reduce battery capacity degradation and energy loss. Compared with the traditional HESS semi-active topology, the proposed improved topology reduces the energy loss when the battery charges the supercapacitor (SC) to further enhance the efficiency of the system. The real urban driving data of electric vehicles are collected through experiments and divided into aggressive type, cautious type and standard type according to driving style. Based on the mature multi-mode control (MMC), different weight coefficients are assigned to the two optimization objectives of battery capacity degradation and energy loss based on different driving styles, and gray wolf optimization (GWO) is used to optimize the battery output power upper limit and SC charging upper limit of MMC. The simulation results show that compared with the traditional MMC and semi-active topology, the battery capacity degradation and energy loss are improved under different driving styles. In addition, by further analyzing the simulation results, the research direction of HESS energy distribution strategy in the future is discussed.
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| 9. |
- Hu, Yingtao, et al.
(author)
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Modeling of solute transport in a fracture-matrix system with a three-dimensional discrete fracture network
- 2022
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In: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 605
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Journal article (peer-reviewed)abstract
- Understanding the fluid flow and solute transport mechanisms in fractured rocks is essential for many geo-engineering applications. In this study, the fluid flow and solute transport in a fracture-matrix system with a three-dimensional (3-D) discrete fracture network (DFN) are modelled through an efficient numerical simulation workflow. The simulation approach is used to systematically investigate the effects of the rock matrix on the transport behaviors in a fracture-matrix system. The results show that the mass exchange between the DFN and the rock matrix can be accurately evaluated based on the conforming mesh at the interface between the fractures (using triangular elements) and the rock matrix (using tetrahedral elements). The complementary cumulative distribution function curves (CCDFs) for the physical processes that consider sorption and decay exhibit significant long tail characteristics, which suggests that the sorption and decay processes play an important role in retarding the migration of solutes in fractured rocks. It is also found that a larger matrix porosity enhances the mass exchange at the interface between the DFN and the rock matrix, which consequently promotes the matrix diffusion effects. The distribution of the concentration plumes in the matrix demonstrates in fracture-matrix systems with larger fracture densities could result in a better connection between the fracture networks and the larger interface (specific wetting) areas, which therefore, promotes the mass exchange. These findings are critical to understanding the migration behavior of radioactive nuclides in far field areas and for the deep geological disposal of nuclear waste.
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| 10. |
- Hu, Yutao, et al.
(author)
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TreeCen : Building Tree Graph for Scalable Semantic Code Clone Detection
- 2022
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In: iWOAR 2022. - New York, NY, USA : Association for Computing Machinery (ACM).
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Conference paper (peer-reviewed)abstract
- Code clone detection is an important research problem that has attracted wide attention in software engineering. Many methods have been proposed for detecting code clone, among which text-based and token-based approaches are scalable but lack consideration of code semantics, thus resulting in the inability to detect semantic code clones. Methods based on intermediate representations of codes can solve the problem of semantic code clone detection. However, graph-based methods are not practicable due to code compilation, and existing tree-based approaches are limited by the scale of trees for scalable code clone detection. In this paper, we propose TreeCen, a scalable tree-based code clone detector, which satisfies scalability while detecting semantic clones effectively. Given the source code of a method, we first extract its abstract syntax tree (AST) based on static analysis and transform it into a simple graph representation (i.e., tree graph) according to the node type, rather than using traditional heavyweight tree matching. We then treat the tree graph as a social network and adopt centrality analysis on each node to maintain the tree details. By this, the original complex tree can be converted into a 72-dimensional vector while containing comprehensive structural information of the AST. Finally, these vectors are fed into a machine learning model to train a detector and use it to find code clones. We conduct comparative evaluations on effectiveness and scalability. The experimental results show that TreeCen maintains the best performance of the other six state-of-the-art methods (i.e., SourcererCC, RtvNN, DeepSim, SCDetector, Deckard, and ASTNN) with F1 scores of 0.99 and 0.95 on BigCloneBench and Google Code Jam datasets, respectively. In terms of scalability, TreeCen is about 79 times faster than the other state-of-the-art tree-based semantic code clone detector (ASTNN), about 13 times faster than the fastest graph-based approach (SCDetector), and even about 22 times faster than the one-time trained token-based detector (RtvNN).
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