| 1. |
- Li, Kefei, et al.
(author)
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Long-term field exposure of structural concretes in marine environment: state-of-the-art review by RILEM TC 289-DCM
- 2022
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In: Materials and Structures/Materiaux et Constructions. - : Springer Science and Business Media LLC. - 1359-5997. ; 55:7
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Journal article (peer-reviewed)abstract
- This paper reviews the technical aspects related to the long-term field exposure practice in marine environments, based on the return of experiences of major marine exposure sites in world-wide scope. The long-term exposure practice helps both the research on durability mechanisms of structural concretes under real environments and the calibration of durability models to support the life-cycle management of concrete structures. The presentation of the field exposure data can be categorized into the information relevant to exposure sites, the data related to the exposed materials and specimens, the information of environmental actions, and the data related to the performance of materials. A standardized presentation of these data can help the efficiency of data sharing and exploitation. The exploitation of exposure data employs various models to represent the chloride ingress and the induced corrosion risk of the embedded steel bars. There are needs for models addressing the strong environment-material interactions, and simple yet reliable durability indicators for engineering use. The design and operation of exposure stations need the careful choice of exposure sites and specimens, the appropriate scheme for monitoring and inspection of exposed specimens, the systematic recording and management of exposure data, and the regular maintenance of exposure facilities. The support of exposure data for life-cycle management is demonstrated through the durability planning of a real project case. The good practice of long-term field exposure is summarized in the end.
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| 2. |
- Fan, Zheyong, et al.
(author)
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GPUMD: A package for constructing accurate machine-learned potentials and performing highly efficient atomistic simulations
- 2022
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In: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 157:11
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Journal article (peer-reviewed)abstract
- We present our latest advancements of machine-learned potentials (MLPs) based on the neuroevolution potential (NEP) framework introduced in Fan et al. [Phys. Rev. B 104, 104309 (2021)] and their implementation in the open-source package gpumd. We increase the accuracy of NEP models both by improving the radial functions in the atomic-environment descriptor using a linear combination of Chebyshev basis functions and by extending the angular descriptor with some four-body and five-body contributions as in the atomic cluster expansion approach. We also detail our efficient implementation of the NEP approach in graphics processing units as well as our workflow for the construction of NEP models and demonstrate their application in large-scale atomistic simulations. By comparing to state-of-the-art MLPs, we show that the NEP approach not only achieves above-average accuracy but also is far more computationally efficient. These results demonstrate that the gpumd package is a promising tool for solving challenging problems requiring highly accurate, large-scale atomistic simulations. To enable the construction of MLPs using a minimal training set, we propose an active-learning scheme based on the latent space of a pre-trained NEP model. Finally, we introduce three separate Python packages, viz., gpyumd, calorine, and pynep, that enable the integration of gpumd into Python workflows.
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| 3. |
- Li, Kefei, et al.
(author)
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RILEM recommendation from TC 289-DCM: guideline for designing and operating long-term marine exposure sites
- 2024
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In: Materials and Structures/Materiaux et Constructions. - 1359-5997. ; 57:3
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Journal article (peer-reviewed)abstract
- This guideline prescribes the technical requirements for the design and operation of long-term exposure sites in marine environments. The technical content includes the design of exposure site, the monitoring of environmental conditions, the monitoring of exposed specimens, the data management and the maintenance of exposure facilities. The design of exposure site covers the choice of exposure sites, the exposure infrastructure and facilities, exposure specimens and their placing and protection. Then, the guideline defines the environmental factors to be monitored and the corresponding monitoring methods. For the exposed specimens, the guideline specifies the target performance to monitor, the sampling, the testing and the reporting of exposure results. The data management deals with such aspects as the data storage, data transmission and the data sharing. At the end, the guideline gives the principles for the maintenance of the exposure facilities. This guideline summarizes the best practice of long-term exposure in marine environments, and it is expected to support the normalization of exposure practice and to generate more added values from this practice.
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| 4. |
- Zeng, Yin, 1996, et al.
(author)
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100-μW Cryogenic HEMT LNAs for Quantum Computing
- 2023
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In: 2023 18th European Microwave Integrated Circuits Conference, EuMIC 2023. ; , s. 71-74
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Conference paper (peer-reviewed)abstract
- Low-power cryogenic LNAs are of interest in future large-scale quantum computing where available cooling capability limits the number of active circuits. We present a comparison of small-signal noise models between two different 100-nm gate-length InP HEMTs at 4 K. The HEMTs were tested in the first stage of a three-stage hybrid cryogenic 4-6 GHz LNA operating at 100-W dc power. The better performing cryogenic LNA exhibited 23.2 dB average gain, 2.0 K average noise temperature, and-55dBm input 1-dB compression point. The enhanced LNA performance was attributed to the improved transconductance of the first-stage HEMT. To the authors' knowledge, this is the lowest noise reported to date for a 100-W transistor-based LNA aimed for qubit readout.
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