| 1. |
- Chen, Fuhao, et al.
(författare)
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Medium-Term Wind Power Forecasting based on Dynamic Self-Attention Mechanism
- 2023
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Ingår i: 2023 IEEE Belgrade PowerTech, PowerTech 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Medium-Term Wind Power Forecasting (MTWPF), with a 7-day forecasting horizon, can provide important support for dispatch plans in the power system and trading strategies in the electricity market. Existing MTWPF methods usually use the Numerical Weather Prediction (NWP) to map the power generated by wind farms. However, the accuracy of the NWP decreases as the forecasting horizon increases, which reduces the performance of the MTWPF. In this paper, we propose a MTWPF model based on multi-head Dynamic Self-Attention mechanism (DSA-MTWPF), which dynamically adjusts the mapping between NWP and wind power according to the change in forecasting horizon. A case study using operational data from one wind farm in China demonstrates that the DSAM-MTWPF outperforms that of the state-of-the-art MTWPF models.
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| 2. |
- Huang, Tianqi, et al.
(författare)
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Failure Characterization of Discrete SiC MOSFETs under Forward Power Cycling Test
- 2024
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 17:11
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Tidskriftsartikel (refereegranskat)abstract
- Silicon carbide (SiC)-based metal-oxide-semiconductor field-effect transistors (MOSFETs) hold promising application prospects in future high-capacity high-power converters due to their excellent electrothermal characteristics. However, as nascent power electronic devices, their long-term operational reliability lacks sufficient field data. The power cycling test is an important experimental method to assess packaging-related reliability. In order to obtain data closest to actual working conditions, forward power cycling is utilized to carry out SiC MOSFET degradation experiments. Due to the wide bandgap characteristics of SiC MOSFETs, the short-term drift of the threshold voltage is much more serious than that of silicon (Si)-based devices. Therefore, an offline threshold voltage measurement circuit is implemented during power cycling tests to minimize errors arising from this short-term drift. Different characterizations are performed based on power cycling tests, focused on measuring the on-state resistance, thermal impedance, and threshold voltage of the devices. The findings reveal that the primary failure mode under forward power cycling tests, with a maximum junction temperature of 130 degrees C, is bond-wire degradation. Conversely, the solder layer and gate oxide exhibit minimal degradation tendencies under these conditions.
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| 3. |
- Jiang, Ziwei, et al.
(författare)
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Characterterization of multi-scale nanosilver paste reinforced with SIC particles
- 2020
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Ingår i: China Semiconductor Technology International Conference 2020, CSTIC 2020.
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Konferensbidrag (refereegranskat)abstract
- Nanosilver paste with high operation temperature and low sintering temperature has attracted more and more attention for its promising application in high power devices. In this paper, the thermal properties of multi-scale nanosilver paste composed of nanometer and micrometer silver particles, and Ag-coated SiC particles were investigated. The thermal conductivity of multi-scale nanosilver paste increases with the increasing amount of SiC particles with Ag coating. The maximum value of Vickers hardness for multi-scale nanosilver paste with 0.5 wt.% Ag-coated SiC particles were 24.
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| 4. |
- Liu, Jianxin, et al.
(författare)
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A novel methodology to directly pre-determine the relative wavelength response of DFB laser in wavelength modulation spectroscopy
- 2019
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 27:2, s. 1249-1261
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Tidskriftsartikel (refereegranskat)abstract
- A novel methodology to directly pre-determine the relative wavelength response (RWR) of a DFB laser, in terms of a combined current linearly scanned wavelength response and current modulated wavelength response (CMWR), in wavelength modulation spectroscopy (WMS) is presented. It is shown that the assessed RWR can be used to mimic the measured response with standard deviation of discriminations that are below 3.4 x 10(-3)cm(-1) under a variety of conditions. It is also shown that its performance supersedes two commonly used assessment models of the CMWR but is slightly worse than that of the third model. however with the benefit of solely using a single fitting parameter (the concentration) instead of more. When the novel method is applied to the assessment of CO2 concentration in a Herriot-type multipass cell by using the technique of calibration-free WMS, the results show that there is virtually no difference compared to that by use of the best of the other methods. It is concluded that the novel method is more robust and simplifies the retrieval process of gas concentration.
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| 5. |
- Lu, Xiuzhen, et al.
(författare)
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Enhanced Mechanical and Thermal Properties of Ag Joints Sintered by Spark Plasma Sintering
- 2022
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 1543-186X .- 0361-5235. ; 51:11, s. 6310-6319
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Tidskriftsartikel (refereegranskat)abstract
- Nano-silver paste has been considered to be one of the most promising materials for interconnects of semiconductor devices operating at high temperature. However, its application is limited by conventional sintering methods due to the long dwell time. In this paper, a spark plasma sintering (SPS) technique with a very short sintering time of no more than 5 min was explored for the sintering of nano-silver paste. The effects of sintering conditions including pretreatment time, sintering temperature, dwell time and applied pressure on shear strength and thermal conductivity of the sintered Ag joints were investigated. The shear strength of sintered Ag joints increased as the sintering temperature and applied pressure increased. Robust sintered Ag joints with an average shear strength of 40.18 MPa were obtained by sintering at 300 degrees C for 5 min under a pressure of 3 MPa. The thermal properties were improved by pretreating the nano-silver paste for a shorter time. Thermal conductivity of 41.50 W m(-1) K-1 is obtained for samples pretreated for 25 min and sintered at 250 degrees C for 5 min.
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| 6. |
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| 7. |
- Sun, Yongqian, et al.
(författare)
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Mechanical properties of a novel multi-scale silver paste for electronics interconnect application
- 2019
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Ingår i: 2019 20th International Conference on Electronic Packaging Technology, ICEPT 2019.
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Konferensbidrag (refereegranskat)abstract
- A novel nano-silver paste with characteristics of sintering at low temperature and operating at high temperature is one of the most promising interconnect materials in the semiconductor industry. This study focuses on the shear strength of sintered multi-scale silver paste synthesized by nano-silver particles, micro-silver particles and submicron silicon carbide particles coated with Ag (SCA). The silver paste was sintered at 250 °C without pressure. The shear strength reaches 9.22 MPa, with 64 wt.% nano-silver particles, 16.5 wt.% micro-silver particles and 1.5 wt.% SCA, respectively. With this, it shows great potential for high power electronics interconnect and cooing applications.
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| 8. |
- Yan, Jie, et al.
(författare)
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Multi-stage transport and logistic optimization for the mobilized and distributed battery
- 2019
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Ingår i: Energy Conversion and Management. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0196-8904 .- 1879-2227. ; 196, s. 261-276
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Tidskriftsartikel (refereegranskat)abstract
- High share of variable renewable energy is challenging to the traditional power system technically and economically. This calls for a significant increase to the system flexibility, which might result in the costs associated with energy storage and costly upgrades to the traditional transmission and distribution system. This paper presents a multi-stage battery transportation and logistics optimization method to increase the renewable energy consumptions, economics, and mobilities of the battery utilization. A new approach is proposed in which the batteries are charged in the renewable power plants and transported back and forth by railways between the renewable power plants and cities. Based on the forecasts of battery supplies/demands, multiple optimization stages (full train transport and carpooling) are designed by the branch-and-bound algorithm and genetic algorithm respectively. The proposed battery transportation and logistics concept and model are performed using the Beijing-Tianjin-Hebei region in China as an example. The results show that the levelized cost of energy of the battery transportation and logistics model is $0.045/kWh averagely. Also, by the use of mobilized batteries, the proposed battery transportation and logistics model increases the system flexibilities and renewable energy deliveries to the end users without the reinforcement of transmission and distribution system and any constraint from a highly penetrated power system.
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| 9. |
- Zhou, Yueting, et al.
(författare)
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Laser frequency stabilization based on a universal sub-Doppler NICE-OHMS instrumentation for the potential application in atmospheric lidar
- 2019
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Ingår i: Atmospheric Measurement Techniques. - Gottingen : Copernicus Gesellschaft MBH. - 1867-1381 .- 1867-8548. ; 12:3, s. 1807-1814
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Tidskriftsartikel (refereegranskat)abstract
- Lidar is an effective tool for high-altitude atmospheric measurement in which a weak absorption line for the target gas is selected to ensure a large optical depth. The laser frequency stabilization to the line center is required, and a sub-Doppler (sD) spectroscopy of the target line is preferred as a frequency reference. In this paper, a novel universal sD noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) instrumentation based on a fiber-coupled optical single-sideband electro-optic modulator (f-SSM) for the potential application in atmospheric lidar for different target gases with different types of lasers is reported. The f-SSM can replace all frequency actuators in the system, so as to eliminate the individual design of feedback servos that often are tailored for each laser. The universality of the instrumentation was demonstrated by the alternative use of either an Er-doped fiber laser or a whispering-gallery mode laser. Then the instruments based on both lasers were used to produce the sD signals of acetylene, which worked as a frequency reference to stabilize the laser. By performing the lockings, relative frequency stabilizations of 8.3 x 10(-13) and 7.5 x 10(-13) at an integration time of 240 s were demonstrated.
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