24 results on '"Ma, Hongliang"'
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2. Recent Advances in Graphene-Based Pressure Sensors: A Review
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Zhang, Zhe, Liu, Quan, Ma, Hongliang, Ke, Ningfeng, Ding, Jie, Zhang, Wendong, and Fan, Xuge
- Abstract
In recent years, pressure sensors have been widely used as crucial technology components in industrial, healthcare, consumer electronics, and automotive safety applications. With the development of intelligent technologies, there is a growing demand for pressure sensors with higher sensitivity, smaller size, and wider detection range. Graphene and its derivatives, as novel emerging materials in recent years, have received widespread attention from researchers due to their unique mechanical and electrical properties and are considered as promising sensing materials for high-performance pressure sensors. In general, graphene-based pressure sensors can be classified into flexible pressure sensors and gas pressure sensors. In this article, we first introduce the basic properties of graphene and its derivatives and then review the research progress of both graphene-based flexible pressure sensors and graphene-based gas pressure sensors, respectively, focusing on different sensing mechanisms. Finally, the application prospects of graphene-based pressure sensors as well as future challenges are discussed. more...
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- 2024
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3. Recent Advances in Graphene-Based Humidity Sensors With the Focus on Structural Design: A Review
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Ma, Hongliang, Ding, Jie, Zhang, Zhe, Gao, Qiang, Liu, Quan, Wang, Gaohan, Zhang, Wendong, and Fan, Xuge
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The advent of the 5G era means that the concepts of robot, virtual reality (VR)/augmented reality (AR), unmanned aerial vehicle (UAV), smart home, and smart healthcare based on Internet of Things (IoT) have gradually entered human life. Since then, intelligent life has become the dominant direction of social development. Humidity sensors, as humidity detection tools, not only convey the comfort of human living environment, but also display great significance in the fields of meteorology, medicine, agriculture, and industry. Graphene-based materials exhibit tremendous potential in humidity sensing owing to their ultrahigh specific surface area and excellent electron mobility under room temperature for application in humidity sensing. This review begins with the introduction of examples of various synthesis strategies of graphene, followed by the device structure and working mechanism of graphene-based humidity sensor. In addition, several different structural design methods of graphene are summarized, demonstrating that the structural design of graphene can not only optimize the performance of graphene, but also bring significant advantages in humidity sensing. Finally, key challenges hindering the further development and practical application of high-performance graphene-based humidity sensors are discussed, followed by presenting the future perspectives. more...
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- 2024
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4. Influence of Litter and Nitrogen Addition on Carbon and Nitrogen Levels in Soil Aggregates under a Subtropical Forest
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Ma, Hongliang, Tecimen, Hüseyin Barış, Wu, Yue, Gao, Ren, and Yin, Yunfeng
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The purpose of this study was to evaluate the responses of carbon (C) and nitrogen (N) in dry and wet sieved aggregates or particles to the litter treatment and N addition, in a forest ecosystem, assuming that the dynamic changes of bulk soil C and N dependent on soil structure and soil fractions. Soil in an evergreen broad-leaf forest (Castanopsis faberi, Hance) has undergone 8 years of N deposition, such as control (CT), low N (LN) and high N (HN), treated as 0, 30 and 100 kg N ha− 1yr− 1for first three years, and 0, 75 and 150 kg N ha− 1yr− 1for last five years, respectively. Concurrently, other treatments were considered as litter removal and litter remaining. Soils were collected and separated first by dry sieving (> 2000 μm, 250–2000 μm, 53–250 μm, < 53 μm). Then the dry sieved large aggregates (> 2000 μm or 250–2000 μm) were dispersed and separated by wet sieving as the six sizes (> 2000 μm, 250–2000 μm, 53–250 μm, < 53 μm, 20–53 μm, < 20 μm). Soil C and N in these soil fractions were investigated. The results revealed that soil aggregates (> 2000 μm, 250–2000 μm, 53–250 μm, < 53 μm) exhibited higher C and N concentrations in smaller particles when dry sieved. However, the C and N concentrations were lower in smaller particles after the wet sieving of the previously dry-sieved aggregates. Specifically, C and N concentrations in 53–250 μm and < 53 μm dry-sieved aggregates surpassed those of the same particle size in the wet-sieving. Overall, both litter and N additions elevated C and N concentrations across all fractions. The presence of litter particularly increased C and N concentrations for soil fractions smaller than 2000 μm, but the extent varied based on the specific size. After dry sieving, the N addition led to more increase in C and N concentrations as aggregate size decreased, especially in the < 53 μm aggregates under high N treatment. Conversely, following wet sieving, N addition resulted in less increase in C and N concentrations as aggregate size decreased. For dry-sieved aggregates, the increase in C and N concentrations due to low N addition in the presence of litter was more on average than that in the absence of litter, and this increase in wet-sieved aggregates due to N addition was inverse. Notably, in the absence of litter, N addition did not induce a decline in C and N. Both the presence of litter and N addition most significantly increased C and N in the 20–53 μm fraction among the wet-sieved soil fractions. The decomposition of litter contributes to C and N in soil aggregates > 250 μm and < 250 μm as different forms, in which water might play an important role for aggregation and C and N storage. Under presence of litter, N deposition is beneficial for improving soil C and N. more...
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- 2024
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5. Global-Scale Assessment of Multiple Recently Developed/Reprocessed Remotely Sensed Soil Moisture Datasets
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Wang, Panshan, Zeng, Jiangyuan, Chen, Kun-Shan, Ma, Hongliang, Zhang, Xiang, Shi, Pengfei, Peng, Chenchen, and Bi, Haiyun
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The comprehensive and robust assessment of diverse global-scale satellite-based soil moisture (SM) products from various satellite data sources (e.g., different frequencies and incidence angles) and retrieval algorithms is essential for the refinements as well as applications of these products. To date, soil moisture retrieval algorithms and products are rapidly evolving and their updated iterations are ongoing. In support of the validation activities of recently developed/reprocessed satellite soil moisture products, the study first assessed eight commonly employed satellite soil moisture datasets comprising soil moisture active passive (SMAP) (DCA, IB, and MTDCA), soil moisture and ocean salinity (SMOS)-IC, Advanced Microwave Scanning Radiometer-2 (AMSR2) [Land Parameter Retrieval Model (LPRM) and Japan Aerospace Exploration Agency (JAXA)], FY-3C, and European Space Agency (ESA) CCI on a global scale using three different strategies, i.e., ERA5 reanalysis soil moisture dataset with similar spatial resolution to satellite products, in situ measurements from densely instrumented networks worldwide with mitigated spatial mismatch between ground site and satellite pixel and the extended triple collocation (ETC) method that can obtain error indicators relative to ground truth. The skills of these products under a broad range of vegetation density, land cover (LC) and climate types, and surface heterogeneity [heterogeneity in terrain, LC, soil texture (ST), and vegetation coverage] were also examined. The results indicate: 1) different soil moisture products show overall consistency in skill ranking under three different evaluation strategies, except for SMAP DCA, SMAP-IB, and SMAP MTDCA in terms of
$R$ $R$ - Published
- 2024
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6. Straw mulching combined with phosphorus fertilization increased photosynthesis rate and grain yield of wheat due to reduced stomatal and mesophyll limitations
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He, Peng, Xie, Wei, Ma, Hongliang, Huang, Xiulan, Zou, Qiaosheng, Ai, Dailong, Haolan, Chen, Fan, Gaoqiong, and Yang, Hongkun
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Phosphorus (P) has been proposed as an important factor determining photosynthesis through improvements in leaf anatomical traits and carboxylation efficiency. However, little is known about the combined effects of straw mulch and P fertilizer on the relationship between flag leaf P content and photosynthesis. This study was conducted to determine the combined effects of straw mulch combined with P fertilizer on wheat flag leaf photosynthetic capacity and grain yield. We performed field experiments during 2020–2022 to investigate the combined effects of straw mulch (0 and 8000 kg ha−1) with P fertilizer (0, 75, and 120 kg P2O5ha−1) in Southwest China. Straw mulch with 75 kg P2O5ha−1gave an 18.3% yield advantage over no mulch with 120 kg P2O5ha−1. Straw mulching with P fertilizer increased flag leaf P content and increased stomatal density. These changes increased stomatal conductance, mesophyll conductance, and net photosynthetic rate (Pn) by 17.4%, 16.3%, and 20.8%, respectively, compared with no‐mulch plots. The increased Pnwas found associated with decreased stomatal and mesophyll limitation. Straw mulching with P fertilizer increased the activities of ribulose‐1,5‐bisphosphate carboxylase‐oxygenase and sucrose synthesis enzymes, thus promoting sucrose synthesis in flag leaves, which is beneficial for increasing grain number per meter square and grain yield. Straw mulching combined with 75 kg P2O5ha−1increased flag leaves P content and stomatal density, and increased stomatal and mesophyll conductance, resulting in improved leaf photosynthesis and grain yield. Straw mulching with phosphorus (P) fertilizer leads to thicker leaves and increased P accumulation, increasing stomatal and mesophyll conductance for high net photosynthetic rate (Pn).Straw mulching with P fertilizer increased carboxylation capacity and ribulose‐1,5‐bisphosphate carboxylase‐oxygenase enzyme activity in leaves, but biochemical limitation is the main limiting factor for Pnenhancement.Straw mulching with P fertilizer increased sucrose export and grain yield by improving photosynthetic capacity and sucrose synthesis. more...
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- 2023
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7. Strong Bacterial Cellulose-Based Films with Natural Laminar Alignment for Highly Sensitive Humidity Sensors
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Ma, Hongliang, Li, Xia, Lou, Jiang, Gu, Yujie, Zhang, Yang, Jiang, Yifei, Cheng, Heli, and Han, Wenjia
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Humidity sensors have been widely used for humidity monitoring in industry and agriculture fields. However, the rigid structure, nondegradability, and large dimension of traditional humidity sensors significantly restrict their applications in wearable fields. In this study, a flexible, strong, and eco-friendly bacterial cellulose-based humidity sensor (BPS) was fabricated using a two-step method, involving solvent evaporation-induced self-assembly and electrolyte permeation. Rapid evaporation of organic solvent induces the formation of nanopores of the bacterial cellulose (BC) surface and promotes structural densification. Furthermore, the successful embedding of potassium hydroxide into the sophisticated network of BC effectively enhanced the sensing performance of BPS. The BPS exhibits an excellent humidity sensing response of more than 103within the relative humidity ranging from 36.4 to 93% and strong (66.4 MPa) and high flexibility properties owing to the ultrafine fiber network and abundant hydrophilic functional groups of BC. Besides being strong and thin, BPS is also highly flexible, biodegradable, and humidity-sensitive, making it a potential candidate in wearable electronics, human health monitoring, and noncontact switching. more...
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- 2022
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8. Contrasting Effects of Alanine and Methionine on Nitrogen Ammonification and Nitrification, and Nitrous Oxide Emissions in Subtropical Forest Soil
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Ma, Hongliang, Imran, Shakeel, Gao, Ren, Yin, Yunfeng, and Raza, Taqi
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The purpose of this study was to evaluate the impacts of two amino acids that contrast in their composition: alanine as a neutral amino acid (represent regular amino acid) and methionine (represent sulfur-containing amino acids) on nitrogen (N) dynamics in acidic subtropical forest soil. 15N-labeled alanine and methionine were added into forest soil to carry out subsequent incubation experiments for 72 h under 60% and 90% of water-holding capacities (WHC) to investigate their potential impacts. The results showed that under 60% of WHC, alanine and methionine added treatment significantly increased the net ammonification rate, except at the 5th h for alanine addition due to alanine immobilized then to prime the soil N ammonification. Alanine addition induced NO3−-N immobilization before 24 h and then nitrification occurred dominantly between 24 and 72 h. However, methionine addition resulted in a lower NO3−-N compared to control indicating that nitrification was likely inhibited. Only methionine added treatment enhanced significantly the net N2O emission rate as compared to that in the control at the 72nd h due to nitrifier denitrification possibly. Under 90% of WHC, the net ammonification rate was significantly higher in the alanine added treatment than in the control, but lower in the methionine added treatment at the 5th h. Amino acids addition significantly decreased the net nitrification rate at the 5th h, but greatly increased the net N2O emissions rate at the 24th h and 72nd h compared to control. Overall, more than 96% of NH4+-N, NO3−-N, and N2O emissions were recorded from soil native N rather than from the added amino acids. Contrasting effects of amino acids should be considered when studying the mechanisms of soil organic N in contributing to the N transformation in subtropical forest soil. more...
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- 2021
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9. Trace gas detection based on photoacoustic spectroscopy in 3-D printed gas cell
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Zha, Shenlong, Ma, Hongliang, Zha, Changli, Cai, Xueyuan, Li, Yuanyuan, Huang, Xing, Wen, Jun, Zhan, Shengbao, and Liu, Kun
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A novel photoacoustic spectroscopy gas sensor based on a micro-resonator has been developed. The photoacoustic cell was designed and fabricated using 3-D printing and the photoacoustic cell volume was compressed significantly. This design greatly reduces the time of manufacturing the micro-resonator and the weight was lighter compared to traditional cells. Furthermore, the acoustic pressure distribution in the 3-D printed photoacoustic cell was analyzed by COMSOL Multiphysics software, which indicated that the strongest acoustic pressure occurred in the middle of the resonant cavity. The performance of the sensor was evaluated by detection of CH_4 at normal atmospheric pressure used a near infrared distributed feedback laser emitted at 1653 nm. The characteristic of the photoacoustic signal under different pressures was also investigated. An Allan variance shows that the 3-D printed photoacoustic spectroscopy sensor has the detection limit of 1.44 ppmv (3σ) for CH_4 detection at about 200 s integration time. more...
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- 2020
10. Trace gas detection based on photoacoustic spectroscopy in 3-D printed gas cell
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Zha, Shenlong, Ma, Hongliang, Zha, Changli, Cai, Xueyuan, Li, Yuanyuan, Huang, Xing, Wen, Jun, Zhan, Shengbao, and Liu, Kun
- Abstract
A novel photoacoustic spectroscopy gas sensor based on a micro-resonator has been developed. The photoacoustic cell was designed and fabricated using 3-D printing and the photoacoustic cell volume was compressed significantly. This design greatly reduces the time of manufacturing the micro-resonator and the weight was lighter compared to traditional cells. Furthermore, the acoustic pressure distribution in the 3-D printed photoacoustic cell was analyzed by COMSOL Multiphysics software, which indicated that the strongest acoustic pressure occurred in the middle of the resonant cavity. The performance of the sensor was evaluated by detection of CH4at normal atmospheric pressure used a near infrared distributed feedback laser emitted at 1653 nm. The characteristic of the photoacoustic signal under different pressures was also investigated. An Allan variance shows that the 3-D printed photoacoustic spectroscopy sensor has the detection limit of 1.44 ppmv (3σ) for CH4detection at about 200 s integration time. more...
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- 2020
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11. Humidity Sensing Properties of Different Atomic Layers of Graphene on the SiO2/Si Substrate
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Gao, Qiang, Ma, Hongliang, He, Chang, Wang, Xiaojing, Ding, Jie, Zhang, Wendong, and Fan, Xuge
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Graphene has great potential to be used for humidity sensing due to its ultrahigh surface area and conductivity. However, the impact of different atomic layers of graphene on the SiO2/Si substrate on humidity sensing has not been studied yet. In this paper, we fabricated three types of humidity sensors on the SiO2/Si substrate based on one to three atomic layers of graphene, in which the sensing areas of graphene are 75 μm × 72 μm and 45 μm × 72 μm, respectively. We studied the impact of both the number of atomic layers of graphene and the sensing areas of graphene on the responsivity and response/recovery time of the prepared graphene-based humidity sensors. We found that the relative resistance change of the prepared devices decreased with the increase of number of atomic layers of graphene under the same change of relative humidity. Further, devices based on tri-layer graphene showed the fastest response/recovery time, while devices based on double-layer graphene showed the slowest response/recovery time. Finally, we chose devices based on double-layer graphene that have relatively good responsivity and stability for application in respiration monitoring and contact-free finger monitoring. more...
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- 2024
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12. Line parameters of ^12CH_4 around 2.008 μm studied by tunable diode laser spectroscopy with a long-path White cell
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Ma, Hongliang, Zha, Shenlong, Cai, Xueyuan, Lin, Guannan, and Cao, Zhensong
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The absorption spectrum of CH_412 at 2.008 μm has been recorded at 296 K, using a high-resolution tunable diode laser absorption spectrometer combined with a long-path, multi-pass White cell. The line positions, intensities, and self-broadening coefficients for 32 transitions of the lower part of the Tetradecad in the 4975–4985 cm^−1 spectral range of CH_412 have been measured. To our knowledge, no experimental information has been obtained for the self-broadening coefficients of these lines before. Comparisons of the line parameters determined in the present work with those from HITRAN2016 line lists are provided. more...
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- 2018
13. Study on focusing of subwavelength imaging of a point source based on two-dimensional photonic crystals
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Ma, Hongliang, Liang, Binming, Zhuang, Songlin, Niu, Jinke, and Chen, Jiabi
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A new focusing structure is proposed, consisting of periodic array air holes in silicon and based on two-dimensional (2D) photonic crystal (PC) with negative refraction and subwavelength imaging characteristics. The light radiating from a point source can form a subwavelength imaging of which the half-width reaches 0.47λ through a wedge PC. Due to the influence of the aberration and evanescent field, the symmetry plane of the image is inside the structure rather than the boundary. In addition, moving the PC by 2 μm to the left horizontally, the image moves by 3.57 μm and the half-width of each image is less than the half-wavelength in this process. more...
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- 2017
14. An Experimental Research on Bone Drilling Temperature in Orthopaedic Surgery
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Hou, Yali, Li, Changhe, Ma, Hongliang, Zhang, Yanbin, Yang, Min, and Zhang, Xiaowei
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The bone drilling temperature fields under different cutting parameters and cooling modes were experimental researched by using common twist drill, diamond punching pin, diamond bullet-like grinding head and diamond spherical grinding head. Three cooling modes were applied, namely, natural air cooling, normal saline pouring cooling and normal saline spray cooling. K-thermocouple was used to measure temperature in bone hole. Results showed that the drill shape could influence drilling temperature greatly. The maximum drilling temperature of diamond spherical grinding head is 46.31°C. The maximum drilling temperature of common twist drill is 42.1°C and that of diamond bullet-like grinding head is 38.29°C. The drilling temperatures at drill speed is under 560 r/min, 900 r/min, 1,250 r/min and 2,100 r/min are 38.84°C, 41.1°C, 43.84°C and 46.31°C. This reflects that under same of other drilling parameters, drilling temperature increases with the increase of drill speed. The maximum bone drilling temperatures of diamond punch pin under 2,100 r/min speed of mainshaft and air cooling conditions vary as feed speed increase firstly and then decrease. The normal saline spray cooling has the lowest maximum drilling temperature of (29.34°C) at same depth, following by normal saline pouring cooling of (32.45°C) and air cooling of (40.28°C) successively. The normal saline spray cooling has the best cooling effect, followed by normal saline pouring cooling and air cooling successively. more...
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- 2015
15. Precise 13CO2/12CO2isotopic ratio measurements for breath diagnosis with a 2-μm diode laser
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Luo, Qingming, Li, Xingde, Gu, Ying, Tang, Yuguo, Sun, Mingguo, Ma, Hongliang, Cao, Zhensong, Liu, Kun, Wang, Guishi, Wang, Lei, Liu, Qiang, and Gao, Xiaoming
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- 2014
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16. An algorithm and observability research of autonomous navigation and joint attitude determination in asteroid exploration descent stage
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Ma, HongLiang, Chen, Tong, and He, YingZi
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In this paper, an autonomous relative navigation and joint attitude determination algorithm in asteroid exploration descent stage is researched based on feature point information of perpendicular asteroid surface image observed by optical navigation camera, distance vectors from spacecraft to asteroid measured by three angled installed lidars and relative velocity increment measured by accelerometer when the relative distance vector to the centroid of asteroid can not be obtained. The inertial attitude of spacecraft is determined by sun vector, star vectors and inertial angular velocity respectively measured by sun sensor, star trackers and inertial reference unit. Also, in order to obtain measurement error model transferred from sensor noise, a covariance matrix solver considering error correlation is presented via the error model of normalized vector to first order. Numerical simulation and improved observability evaluation of filtering are undertaken to discuss the results of complete sensor observation and weak observation of lidars, and verify the effectiveness of the presented relative navigation and attitude determination algorithm. more...
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- 2014
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17. A Novel Fusion Method for Generating Surface Soil Moisture Data With High Accuracy, High Spatial Resolution, and High Spatio‐Temporal Continuity
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Huang, Shuzhe, Zhang, Xiang, Chen, Nengcheng, Ma, Hongliang, Fu, Peng, Dong, Jianzhi, Gu, Xihui, Nam, Won‐Ho, Xu, Lei, Rab, Gerhard, and Niyogi, Dev
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Surface soil moisture (SSM) has a considerable impact on land‐atmosphere exchanges of water and energy fluxes. However, due to the inherent deficiencies of remotely sensed data (e.g., cloud contamination in thermal remote sensing and coarse resolutions for microwave remote sensing), none of the current algorithms alone can provide daily and seamless field‐scale (30 m) SSM information. To fill the gap, we proposed a novel SSM fusion framework to Generate high Resolution, Accurate, Seamless data using Point‐Surface fusion (GRASPS) based on remotely sensed, reanalysis, and in‐situ data sets. First, 30 m seamless continuous SSM correlated variables (land surface temperature, NDVI, and albedo) were downscaled by enhanced spatial and temporal adaptive reflectance fusion model. Then, downscaled auxiliary variables and other background variables were input into a deep learning model to produce 30 m daily and seamless SSM fields. To further improve the SSM estimation accuracy, a pixel classification‐based bias correction method was developed. The GRASPS method was validated over an in situ soil moisture sensor network (HOAL network) in Austria. The average Pearson correlation coefficient, root mean square error (RMSE), unbiased RMSE (ubRMSE), bias, and mean absolute error (MAE) over all validation sites achieved 0.78, 0.048, 0.033, −0.001, and 0.041 m3m−3${\mathrm{m}}^{3}{\mathrm{m}}^{-3}$, respectively. After bias correction, RMSE, ubRMSE, bias, and MAE decreased by 13%, 7%, 22%, and 18%, respectively. The proposed method maximizes the potential of data fusion and deep learning in generating field‐scale seamless SSM, which is promising for fine‐scale studies and applications in agricultural, hydrological, and environmental domains. The proposed framework applied point‐surface data fusion through deep learning30 m seamless surface soil moisture (SSM) with high accuracy was generatedDownscaled SSM showed good agreement with in situ SSM observations The proposed framework applied point‐surface data fusion through deep learning 30 m seamless surface soil moisture (SSM) with high accuracy was generated Downscaled SSM showed good agreement with in situ SSM observations more...
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- 2022
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18. Subwavelength imaging of a point source based on two-dimensional photonic crystals
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Ma, Hongliang, Liang, Binming, Zhuang, Songlin, Chen, Jiabi, Jiang, Qiang, and Ding, Junwei
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A new two-dimensional (2D) photonic crystal (PC) structure with effective refractive index approaching −1, consisting of periodic array air holes in silicon, is proposed. The light radiated from a point source can form an image through a single wedge PC. Numerical results show that the half-width of the image reaches 0.44λ, which is lower than half of the incident wavelength. In addition, the light through the combination of two of the same PCs can also form subwavelength imaging of which the half-width reaches 0.67λ, and the image almost flipped 180° compared with a point source. more...
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- 2016
19. Positron annihilation study of PbWO4 crystal doped with Y2O3 at different concentration
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Xie, Jianjun, Geng, Zhengsong, Yuan, Hui, Xiong, Wei, Chen, Liang, Ye, Chongzhi, Xu, Guoqing, Hao, Xiaopeng, Zhang, Zhiming, Ma, Hongliang, Gu, Mu, Feng, Xiqi, and Liao, Jingying
- Abstract
A study of vacancy-related defects in yttrium-doped PbWO4 with doping concentration of 0–1 mol% has been performed using X-ray diffraction and positron annihilation lifetime spectroscopy. It was found that the samples have vacancy-like defects that act as positron traps. Two main defect lifetime components were found in all samples, one at about 0.195 ns to 0.208 ns and the other about 0.408 ns to 0.735 ns. These defect trapping sites can be attributed to single Pb-site vacancies and interstitial oxygen ions, respectively. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) more...
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- 2008
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20. Suppression of intensity noise of a laser-diode-pumped single-frequency Nd:YVO_4 laser by optoelectronic control
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Zhang, Jing, Ma, Hongliang, Xie, Changde, and Peng, Kunchi
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The intensity-noise reduction of a laser-diode-pumped single-frequency ring Nd:YVO_4 laser when different optoelectronic control systems are used is theoretically and experimentally investigated. It has been demonstrated that combining two techniques, optoelectronic feedback control of the drive current of the pump laser diode and feed-forward control of the output laser beam, is a good way to significantly suppress the intensity noise of a laser at low frequency. more...
- Published
- 2003
21. Measurement of hyperfine structure in the lines 578.77 nm and 587.04 nm of PrII
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Li, Maosheng, Ma, Hongliang, Chen, Miaohua, Chen, Zhijun, Lu, Fuquan, Tang, Jiayong, and Yang, Fujia
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The hyperfine structure of the transitions 4f3(4Io)5d 3I5o–4f3(4Io)6p 5I5(578.77 nm) and 4f3(4Io)5d 3I6o–4f3(4Io)6p? (J=5) (587.04 nm) of 141PrII has been measured by collinear laser‐ion‐beams spectroscopy. The magnetic‐dipole constant A and the electric‐quadrupole constant B of the involved levels have been determined. more...
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- 2000
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22. Femtosecond laser writing of Er^3+-doped CaF_2 crystalline patterns in glass
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Liu, Yin, Zhu, Bin, Dai, Ye, Qiao, Xvsheng, Ye, Song, Teng, Yu, Guo, Qingtian, Ma, Hongliang, Fan, Xianping, and Qiu, Jianrong
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We report on the use of 800 nm, 250 kHz femtosecond laser pulses to precipitate Er^3+-doped CaF_2 crystals inside oxyfluoride glass, which was confirmed with x-ray diffraction analysis. Confocal upconversion luminescence spectra show that the precipitated crystals have greatly enhanced upconversion luminescence intensity in comparison with unmodified glass. We demonstrate the possibility of three-dimensional optical data storage in the glass by the use of the confocal upconversion luminescence imaging. more...
- Published
- 2009
23. Greatly enhanced effect of silver on femtosecond laser-induced precipitation of nonlinear optical crystals in glasses
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Zhu, Bin, Liu, Yin, Ye, Song, Qian, Bin, Lin, Geng, Dai, Ye, Ma, Hongliang, and Qiu, Jianrong
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We report greatly enhanced femtosecond laser-induced precipitation of nonlinear optical crystals in glasses owing to the addition of silver. Ba_2TiSi_2O_8 (BTS) crystals were space-selectively precipitated inside a Ag^+-doped BaO–TiO_2–SiO_2 glass by using a focused femtosecond laser with 800 nm, 250 kHz, and 150 fs. The laser induced crystals were confirmed by micro-Raman spectra to be BTS phases. The irradiation time for crystallization in Ag^+-doped BaO–TiO_2–SiO_2 glasses was much shorter than that in undoped BaO–TiO_2–SiO_2 glasses under the same irradiation conditions. The mechanism responsible for the observed phenomenon is discussed. more...
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- 2009
24. Effect of spatio-temporal coupling on ultrafast laser direct writing in glass
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Li, Qin, Li, Wenbo, Chu, Wei, Cao, Yuxiang, Zhang, Wencheng, Ma, Hongliang, Jin, Zuanming, and Dai, Ye
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Spatio-temporal coupling characteristics of ultrafast laser pulses are quantitatively tailored. An asymmetric microstructure is induced in the focal volume when the laser scans perpendicularly to the direction of the spatial chirp in fused silica. The tilted direction reverses when adding a Dove prism into the light path. The sign of the pulse front tilt can be turned from positive to negative by changing the group delay dispersion by steps. We reveal that the tilted direction of a microstructure depends on spatial chirp, and the interplay between spatio-temporal chirp leads to the change of tilted angles. more...
- Published
- 2019
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