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| 1 | Absolute calibration of HY-2A and Jason-2 altimeters for sea surface height using GPS buoy in Qinglan, China显示文摘GPS buoy methodology is one of the main calibration methodologies for altimeter sea surface height calibration. This study introduces the results of the Qinglan calibration campaign for the HY-2A and Jason-2 altimeters. It took place in two time slices;one was from August to September 2014, and the other was in July 2015. One GPS buoy and two GPS reference stations were used in this campaign. The GPS data were processed using the real-time kinematic (RTK) technique. The fi nal error budget estimate when measuring the sea surface height (SSH) with a GPS buoy was better than 3.5 cm. Using the GPS buoy, the altimeter bias estimate was about -2.3 cm for the Jason-2 Geophysical Data Record (GDR) Version ‘D' and from -53.5 cm to -75.6 cm for the HY-2A Interim Geophysical Data Record (IGDR). The bias estimates for Jason-2 GDR-D are similar to the estimates from dedicated calibration sites such as the Harvest Platform, the Crete Site and the Bass Strait site. The bias estimates for HY-2A IGDR agree well with the results from the Crete calibration site. The results for the HY-2A altimeter bias estimated by the GPS buoy were verifi ed by cross-calibration, and they agreed well with the results from the global analysis method. | CHEN Chuntao ZHU Jianhua ZHAI Wanlin YAN Longhao ZHAO Yili HUANG Xiaoqi YANG Weiwei | 2019 | Journal of Oceanology and Limnology2019，37，5： | 5 |
| 2 | Preliminary calibration results of the HY-2B altimeter’s SSH at China’s Wanshan calibration site显示文摘Satellite altimeter needs to be calibrated to evaluate the accuracy of sea surface height data.The dedicated altimeter calibration field needs to establish a special calibration strategy and needs to evaluate its calibration ability.This paper describes absolute calibration of HY-2 B altimeter SSH using the GPS calibration method at the newly Wanshan calibration site,located in the Wanshan Islands,China.There are two HY-2 B altimeter passes across the Wanshan calibration site.Pass No.362 is descending and the ground track passes the east of Dan’gan Island.Pass No.375 is ascending and crosses the Zhiwan Island.The GPS data processing strategy of Wanshan calibration site was established and the accuracy of GPS calibration method of Wanshan calibration site was evaluated.Meanwhile,the processing strategies of the HY-2 B altimeter for the Wanshan calibration site were established,and a dedicated geoid model data were used to benefit the calibration accuracy.The time-averaged HY-2 B altimeter bias was approximately 2.12 cm with a standard deviation of 2.08 cm.The performance of the HY-2 B correction microwave radiometer was also evaluated in terms of the wet troposphere path delay and showed a mean difference-0.2 cm with a 1.4 cm standard deviation with respect to the in situ GPS radiosonde. | Chuntao Chen Jianhua Zhu Chaofei Ma Mingsen Lin Longhao Yan Xiaoqi Huang Wanlin Zhai Bo Mu Yongjun Jia | 2021 | Acta Oceanologica Sinica2021，40，5： | 2 |
| 3 | Preliminary calibration results for Jason-3 and Sentinel-3 altimeters in the Wanshan Islands显示文摘We present preliminary calibration results for Jason-3 and Sentinel-3A altimeters that we set up in the Wanshan Islands in Guandong Province,China.Two campaigns were carried out in 2018,from March 8 to April 16 and from November 3 to December 11,2018.Three GPS reference stations and tide gauges were established on the islands of Zhiwan,Dangan,and Wailingding during the campaigns.The in-situ sea surface height(SSH)of the altimeter footprint was determined using the tide gauge.The tidal and geoid connection between the tide gauge locations and the altimeter footprints were computed with the NAO.99Jb tidal prediction system and the EGM 2008 geoid,respectively.The data of the tide gauges were defi ned using the GPS buoy and GPS reference stations during the campaigns.The results show that the waveform of the altimeters was slightly contaminated by the small islands.The bias associated with Jason-3 and Sentinel-3A amounted to approximately+20.7±49.7 mm and+30.1±39.4 mm,respectively,which agreed well with the results from other in-situ calibration fi elds.This indicates that the Wanshan area was very suitable as an in-situ calibration/validation fi eld.The wet zenith delay(WZD)determined from the Microwave Radiometer(MWR)and the GPS measurements diff ered from each other for the Jason-3 and Sentinel-3A by−6.6±7.4 mm and 0±6.8 mm,respectively. | Wanlin ZHAI Jianhua ZHU Xiaohui FAN Longhao YAN Chuntao CHEN Zhen TIAN | 2021 | Journal of Oceanology and Limnology2021，39，2： | 1 |
| 4 | NAS4RRAM: neural network architecture search for inference on RRAM-based accelerators显示文摘The RRAM-based accelerators enable fast and energy-efficient inference for neural networks.However, there are some requirements to deploy neural networks on RRAM-based accelerators, which are not considered in existing neural networks.(1) Because the noise problem and analog-digital converters/digitalanalog converters(ADC/DAC) affect the prediction accuracy, they should be modeled in networks.(2) Because the weights are mapped to the RRAM cells, they should be quantized, and the number of weights is limited by the number of RRAM cells in the accelerator. These requirements motivate us to customize the hardware-friendly network for the RRAM-based accelerator. We take the idea of network architecture search(NAS) to design networks with high prediction accuracy that meet the requirements. We propose a framework called NAS4RRAM to search for the optimal network on the given RRAM-based accelerator. The experiments demonstrate that NAS4RRAM can apply to different RRAM-based accelerators with different scales. The performance of searched networks outperforms the manually designed ResNet. | Zhihang YUAN Jingze LIU Xingchen LI Longhao YAN Haoxiang CHEN Bingzhe WU Yuchao YANG Guangyu SUN | 2021 | Science China(Information Sciences)2021，64，6： | 0 |
| 5 | Obtaining accurate measurements of the sea surface height from a GPS buoy显示文摘A dedicated GPS buoy is designed for calibration and validation(Cal/Val)of satellite altimeters since 2014.In order to evaluate the accuracy of the sea surface height(SSH)measured by the GPS buoy,twelve campaigns have been done within China sea area between 2014 and 2021.In six of these campaigns,two static Global Navigation Satellite System stations were installed at distances of<1 km and 19 km from the buoy to assess how the baseline length influenced the derived SSH from the buoy solutions.The GPS buoy data was processed using the GAMIT/GLOBK software+TRACK module and CSRS-PPP tool to achieve the SSH.The SSH was compared with conventionally tide gauge(TG)data to evaluate the accuracy of the buoy with the standard deviation of the height element.The results showed that the difference in the standard deviation of the SSH from the buoy and the TG was less than 16 mm.The SSHs processed with different ephemeris(Ultra-Rapid,Rapid,Final)were not significantly different.When the baseline length was 19 km,the SSH solution of the GPS buoy performed well,with standard bias of less than 26 mm between the heights measured by the buoy and TG,meaning that the buoy could be used for Cal/Val of altimeters.The bias between the Canadian Spatial Reference System-precise point positioning tool and the TRACK varied a lot,and some of them were over 130 mm.This deemed too high to be useful for Cal/Val of satellite altimeters.Moreover,the GPS buoy solutions processed by GAMIT/GLOBK software+TRACK module were used for in-orbit Cal/Val of HY-2B/C satellites in ten campaigns.The SSH and significant wave height of the altimeters showed good agreements with the GPS buoy solutions. | Wanlin Zhai Jianhua Zhu Chuntao Chen Wu Zhou Longhao Yan Yufei Zhang Xiaoqi Huang Kai Guo | 2023 | Acta Oceanologica Sinica2023，42，6： | 0 |
| 6 | A Primary Study on Mechanical Properties of Heat-Treated Wood via in-situ Synthesis of Calcium Carbonate显示文摘This study aims to improve the value of fast-growing wood and extend the heat-treated wood utilization using inorganic calcium carbonate(CaCO_(3))crystals via an in-situ synthesis method.CaCl_(2)and Na 2CO_(3)solutions with a concentration ratio of 1:1 were successively introduced into the thermally modified poplar wood obtained by steam heat treatment(HT)at 200℃for 1.5 and 3 h,resulting in the in-situ synthesis of CaCO_(3)crystals inside the heat-treated wood.The filling effect was best at the concentration of 1.2 mol/L.CaCO_(3)was uniformly distributed in the cell cavities of the heat-treated wood,and some of the crystals were embedded in the fissures of the wood cell walls.The morphology of CaCO_(3)crystals was mainly spherical and rhombic polyhedral.Three main types of CaCO_(3)crystals were calcite,vaterite,and aragonite.The HT of poplar wood at 200℃resulted in degrading the chemical components of the wood cell wall.This degradation led to reduced wood mechanical properties,including the surface hardness(HD),modulus of rupture(MOR),and modulus of elasticity(MOE).After CaCO_(3)was in-situ synthesized in the heat-treated wood,the HD increased by 18.36%and 16.35%,and MOR increased by 14.64%and 8.89%,respectively.Because of the CaCO_(3)synthesization,the char residue of the 200℃heat-treated wood samples increased by 9.31%and the maximum weight loss rate decreased by 19.80%,indicating that the filling with CaCO_(3)cannot only improve the mechanical properties of the heat-treated wood but also effectively enhance its thermal stability. | Dianen Liang Zhenhao Ding Qilin Yan Redžo Hasanagić Leila Fathi Zi Yang Longhao Li Jianbo Wang Houhua Luo Qian Wang Demiao Chu | 2023 | Journal of Renewable Materials2023，11，1： | 0 |
| 7 | Measurement of the sea surface using a GPS towing-body in Wanshan area显示文摘Wanshan area has been chosen to be the specified field to calibrate and validate(Cal/Val)the HY-2 altimeter and its follow-on satellites.In March 2018,an experiment has been conducted to determine the sea surface height(SSH)under the HY-2 A ground track(Pass No.203).A GPS towing-body(GPS-TB)was designed to measure the SSH covering an area of about 6 km×28 km wide centered on the HY-2 A altimeter satellite ground track.Three GPS reference stations,one tide gauge and a GPS buoy were placed in the research area,in order to process and resolve the kinematic solution and check the precision of the GPS-TB respectively.All the GPS data were calculated by the GAMIT/GLOBK software and TRACK module.The sea surface was determined by the GPS-TB solution and the tide gauge placed on Zhiwan Island.Then the sea surface of this area was interpolated by Arc GIS10.2 with ordinary Kriging method.The results showed that the precision of the GPS-TB is about 1.10 cm compared with the tide gauge placed nearby,which has an equivalent precision with the GPS buoy.The interpolated sea surface has a bias of–1.5–4.0 cm with standard deviation of 0.2–2.4 cm compared with the checking line.The gradient of the measured sea surface is about 1.62 cm/km along the HY-2 orbit which shows a good agreement compared with the CLS11 mean sea surface(MSS).In the Cal/Val of satellites,the sea surface between the tide gauge/GPS buoy and the footprint of altimeter can be improved by this work. | Wanlin Zhai Jianhua Zhu Chaofei Ma Xiaohui Fan Longhao Yan He Wang Chuntao Chen | 2020 | Acta Oceanologica Sinica2020，39，5： | 0 |
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