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  • MDPI AG  (110)
  • Wang, Xiaoming  (110)
  • 1
    Online Resource
    Online Resource
    Multiobjective Optimization of SiC Mirror Based on Dual-Parameter Coupling
    MDPI AG ; 2023
    In:  Photonics Vol. 10, No. 2 ( 2023-02-07), p. 171-
    Details
    In: Photonics, MDPI AG, Vol. 10, No. 2 ( 2023-02-07), p. 171-
    Abstract: For photoelectric theodolite, the mirror is the core optical component, so it is of great significance to design and optimize a mirror with excellent overall performance. In order to comprehensively consider the contradictory objectives of mass, natural frequency, and RMS under gravity, a multiobjective optimization method based on the performance analysis of two-parameter coupling was proposed. On the basis of the performance law, a suitable solution for balancing multiple objective functions is obtained by introducing manual intervention. The results show that compared with the traditional empirical design of mirrors, the first-order natural frequency, mass, and RMS performance of the optimized mirror are improved by 18.64%, 0.1%, and 15.58%, respectively. The frequency/Mass ratio and 1/(RMS*Mass) ratio are increased by 18.72% and 18.59%, respectively. Its comprehensive performance has been improved. This method is effective and provides a reference for the design of photoelectric theodolite and other mirrors.
    Type of Medium: Online Resource
    ISSN: 2304-6732
    URL: Article
    DOI: 10.3390/photonics10020171
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2770002-1
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  • 2
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    Assessment of Multiple GNSS Real-Time SSR Products from Different Analysis Centers
    MDPI AG ; 2018
    In:  ISPRS International Journal of Geo-Information Vol. 7, No. 3 ( 2018-03-08), p. 85-
    Details
    In: ISPRS International Journal of Geo-Information, MDPI AG, Vol. 7, No. 3 ( 2018-03-08), p. 85-
    Type of Medium: Online Resource
    ISSN: 2220-9964
    URL: Article
    DOI: 10.3390/ijgi7030085
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2655790-3
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  • 3
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    Microstructure, Microhardness and Tribological Properties of Bronze–Steel Bimetallic Composite Produced by Vacuum Diffusion Welding
    MDPI AG ; 2022
    In:  Materials Vol. 15, No. 4 ( 2022-02-20), p. 1588-
    Details
    In: Materials, MDPI AG, Vol. 15, No. 4 ( 2022-02-20), p. 1588-
    Abstract: In this paper, a lead–bronze/steel bimetal composite was produced by vacuum diffusion welding technology. The microstructure, hardness and tribological properties under the dry sliding condition of the bimetal structured material were investigated and compared with two reference samples, i.e., lead–bronze and Mn/Si–brass. The wear mechanism of the three materials was also analyzed in detail. It was found that the bimetallic structure possessed the best wear resistance among the three samples. When paired with the ball bearing steel, the wear rates of the lead–bronze and Mn/Si–brass were 13 and 54 times higher than that of the bimetal composite. When paired with bearing steel, the wear rates of the two materials were 13 and 54 times higher than the bimetallic composite, respectively. This is because the steel layer served as a bearing layer to decrease the plastic deformation of the bronze layer. Furthermore, the lead can accelerate the formation of a dense hardened layer at the sliding interfaces to avoid subsequent wear of the bronze surface. Nevertheless, this hardened layer caused severe scuffing on the steel balls. Therefore, lead–bronze/steel structured material is recommended to match with hard counterface material, such as cemented carbide.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma15041588
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2487261-1
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  • 4
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    YSZ/LSM Composite Cathode Deposited by Solution Precursor Plasma Spraying
    MDPI AG ; 2022
    In:  Coatings Vol. 12, No. 3 ( 2022-02-28), p. 321-
    Details
    In: Coatings, MDPI AG, Vol. 12, No. 3 ( 2022-02-28), p. 321-
    Abstract: In this paper, solution precursor plasma spraying (SPPS) was employed to prepare a porous YSZ/LSM composite cathode for solid oxide fuel cell (SOFC). The surface morphology and microstructure of the composite cathode deposits were characterized using SEM. The effect of annealing treatment on SPPS YSZ/LSM microstructure was examined. The results showed that the as-sprayed YSZ/LSM deposits presented a porous aggregate with a size range of 10–60 μm when the alcohol was used as the solvent and the spraying distance was 60 mm. The porous aggregate was found to be composed mainly of small particles ranging from 0.2–2 μm, the YSZ/LSM composite cathode showed a finely porous microstructure with grain sizes from micrometers to sub-micrometers. A further annealing treatment at 1050 °C for 2 h in air resulted in a continuous microstructure porous coating with a perovskite phase. The polarization test results demonstrated that the minimum polarizations were 1.26 and 0.083 Ω·cm2 for the composite cathode at 800 and 1000 °C, respectively.
    Type of Medium: Online Resource
    ISSN: 2079-6412
    URL: Article
    DOI: 10.3390/coatings12030321
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2662314-6
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  • 5
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    A Novel Construction Technology for Self-Anchored Suspension Bridge Considering Safety and Sustainability Performance
    MDPI AG ; 2020
    In:  Sustainability Vol. 12, No. 7 ( 2020-04-08), p. 2973-
    Details
    In: Sustainability, MDPI AG, Vol. 12, No. 7 ( 2020-04-08), p. 2973-
    Abstract: To promote sustainable development of civil infrastructures, minimizing environmental impact and mobility disruptions have been elevated to a higher priority during decision-making for bridge construction scheme. This study presents a novel temporary pylon-anchor (TPA) technology for construction of self-anchored suspension bridges by considering not only safety performance, but also environmental impacts. A practical assessment method and index of sustainability associated with bridge construction technology are established to facilitate the selection of construction schemes. The sustainability index takes the environmental impact, traffic disruption, onsite construction materials and equipment, onsite construction cost, and onsite construction risk into consideration. The sustainability index associated with both conventional and novel construction methods is assessed and compared in this paper. Specifically, a novel girder-pylon antithrust system (GPAS) is proposed, which is the crucial component of the TPA technology in engineering application. In addition, an analytical approach is developed, considering both global load-carrying capacity and local stress distribution within the design and construction of the GPAS. The applicability and rationality of the proposed construction technology are illustrated by the successful application in real-world engineering. The field tests and sustainability assessment during the construction stage reveal that the proposed sustainability assessment method and analytical approach can facilitate the implementation of sustainable construction for self-anchored suspension bridges by considering both construction safety and sustainability.
    Type of Medium: Online Resource
    ISSN: 2071-1050
    URL: Article
    DOI: 10.3390/su12072973
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2518383-7
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  • 6
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    A Novel Method of Seismic Signal Detection Using Waveform Features
    MDPI AG ; 2020
    In:  Applied Sciences Vol. 10, No. 8 ( 2020-04-23), p. 2919-
    Details
    In: Applied Sciences, MDPI AG, Vol. 10, No. 8 ( 2020-04-23), p. 2919-
    Abstract: The detection of seismic signals is vital in seismic data processing and analysis. Many algorithms have been proposed to resolve this issue, such as the ratio of short-term and long-term power averages (STA/LTA), F detector, Generalize F, and etc. However, the detection performance will be affected by the noise signals severely. In this paper, we propose a novel seismic signal detection method based on the historical waveform features to improve the seismic signals detection performance and reduce the affection from the noise signals. We use the historical events location information in a specific area and waveform features information to build the joint probability model. For the new signal from this area, we can determine whether it is the seismic signal according to the value of the joint probability. The waveform features used to construct the model include the average spectral energy on a specific frequency band, the energy of the component obtained by decomposing the signal through empirical mode decomposition (EMD), and the peak and the ratio of STA/LTA trace. We use the Gaussian process (GP) to build each feature model and finally get a multi-features joint probability model. The historical events location information is used as the kernel of the GP, and the historical waveform features are used to train the hyperparameters of GP. The beamforming data of the seismic array KSRS of International Monitoring System are used to train and test the model. The testing results show the effectiveness of the proposed method.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app10082919
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2704225-X
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  • 7
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    Evaluating Gyratory Compaction Characteristics of Unbound Permeable Aggregate Base Materials from Meso-Scale Particle Movement Measured by Smart Sensing Technology
    MDPI AG ; 2021
    In:  Materials Vol. 14, No. 15 ( 2021-07-31), p. 4287-
    Details
    In: Materials, MDPI AG, Vol. 14, No. 15 ( 2021-07-31), p. 4287-
    Abstract: The quality of compaction of unbound aggregate materials with permeable gradation plays a vital role in their field performance; however, there are currently few unanimously accepted techniques or quality control criteria available for ensuring adequate compaction of such materials in either laboratory or field applications. This paper presented testing results of a laboratory gyratory compaction study where the combinations of gyratory parameters were properly designed using the orthogonal array theory. Innovative real-time particle motion sensors were employed to record particle movement characteristics during the compaction process and provide a meso-scale explanation about compaction mechanisms. Particle abrasion and breakage were also quantified from particle shape digitized from the three-dimensional (3D) laser scanner before and after compaction. The optimal combination of gyratory parameters that yields the best compaction performance was determined from the orthogonal testing results with the relative importance of major influencing parameters ranked accordingly. Meso-scale particle movement at the upper center and center side positions of the specimen are promising indicators of compaction quality. The gyratory compaction process can be consistently divided into three distinct stages according to both macro-scale performance indicators and meso-scale particle movement characteristics. A statistically significant bi-linear relationship was found to exist between relative breakage index and maximum abrasion depth, whereas the quality of compaction and the extent of particle breakage appear to be positively correlated, thus necessitating the cost-effective balance between them. The results of this study could provide technical insights and guidance to field compaction of unbound permeable aggregates.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma14154287
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
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  • 8
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    Effects of Melt Hydrogenation on the Microstructure Evolution and Hot Deformation Behavior of TiBw/Ti-6Al-4V Composites
    MDPI AG ; 2023
    In:  Materials Vol. 16, No. 6 ( 2023-03-21), p. 2496-
    Details
    In: Materials, MDPI AG, Vol. 16, No. 6 ( 2023-03-21), p. 2496-
    Abstract: In this study, Ti-6Al-4V matrix composites reinforced with TiB ceramic whiskers were in situ synthesized and hydrogenated using the melt hydrogenation technique (MHT). The effects of MHT on the microstructure evolution and hot compression behavior of the composites were investigated by optical microscopy (OM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Hot compression tests were performed at strain rates of 0.1/s, 0.01/s, and 0.001/s and temperatures of 800 °C, 850 °C, and 900 °C; the hot workability of composites significantly improved after hydrogenation, for example, the 900 °C peak flow stress of hydrogenated composites (43 MPa) decreased by 53.76% compared with that of unhydrogenated ones (93 MPa) at a strain rate of 0.01/s. Microstructural observations show that MHT can effectively facilitate the dispersion of TiB whiskers and induce the α/β lath refinement of the matrix in our as-cast hydrogenated composite. During hot compression, MHT effectively promoted the as-cast composite microstructure refinement, accelerated the dynamic recrystallization (DRX) generation, and reduced the stress concentration at the interface between the reinforcement and matrix; in turn, the hydrogenated composites presented low peak stress during hot compression.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma16062496
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
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  • 9
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    Pavement Strategy Optimization of Cable-Stayed Bridges against the Negative Reaction Risks of Auxiliary Piers
    MDPI AG ; 2023
    In:  Applied Sciences Vol. 13, No. 8 ( 2023-04-13), p. 4877-
    Details
    In: Applied Sciences, MDPI AG, Vol. 13, No. 8 ( 2023-04-13), p. 4877-
    Abstract: Because the adjustment of the stay cable tension and girder counterweight is limited at the operation stage it is a difficult problem to control the negative reaction risk of the auxiliary pier (NRRAP) caused by multisource construction uncertainties and traffic growth. This paper proposes a pavement strategy optimization to control the NRRAP by adjusting the pavement thickness. The pavement strategy optimization is formulated as a reliability-constrained, multiobjective optimization problem, which is resolved by the nondominated sorting genetic algorithm (NSGA-II). A sensitivity analysis and a reliability analysis based on the generalized regression neural network (GRNN) surrogate model were performed to illustrate the significance of the uncertainty level in auxiliary pier negative reactions. The Pareto front examines the balance of construction cost, driving comfort and specified reliability threshold. The efficiency and accuracy of the proposed method are validated in a real cable-stayed bridge, and the results exhibit its advantages in controlling the NRRAP.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app13084877
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
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  • 10
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    GAN-LSTM Joint Network Applied to Seismic Array Noise Signal Recognition
    MDPI AG ; 2021
    In:  Applied Sciences Vol. 11, No. 21 ( 2021-10-25), p. 9987-
    Details
    In: Applied Sciences, MDPI AG, Vol. 11, No. 21 ( 2021-10-25), p. 9987-
    Abstract: The purpose of seismic data processing in nuclear explosion monitoring is to accurately and reliably detect seismic or explosion events from complex ambient noises. Accurate detection and identification of seismic phases are of great significance to the detection and parameter estimation of seismic events. In seismic phase identification, discriminating between noise signals and real seismic signals is essential. Accurate identification of noise signals helps reduce false detections, improves the accuracy of automatic bulletins, and relieves the workload of analysts. At the same time, in seismic exploration, the prime objective in data processing is also to enhance the signal and suppress the noises. In this study, we combined a generative adversarial network (GAN) with a long short-term memory network (LSTM) to discriminate between noise and phases in seismic waveforms recorded by the International Monitoring System (IMS) array MKAR. First, using the beamforming data of the array as the input, we obtained the signal features of seismic phases through the learning of the GAN discriminator network. Then, we input these features and trained the joint network on mixed seismic phase and noise data, and successfully classified seismic phases and noise signals with a recall of 95.28% and 97.64%, respectively. Based on this model, we established a real-time data processing method, then validated the effectiveness of this method with real 2019 data of MKAR. We also verified whether improved noise signal identification improves the quality of phase association and event detection.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app11219987
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
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