77 results on '"Jianzhu Li"'
Search Results
2. Considering flood scaling property in multi-objective calibration of the SWAT model: a case study in Zijinguan watershed, Northern China
- Author
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Yanchen Zheng, Jianzhu Li, Ting Zhang, Youtong Rong, and Ping Feng
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Atmospheric Science ,Earth and Planetary Sciences (miscellaneous) ,Water Science and Technology - Published
- 2023
3. Wafer-Scale Growth of Sb2Te3 Films via Low-Temperature Atomic Layer Deposition for Self-Powered Photodetectors
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Jun Yang, Jianzhu Li, Amin Bahrami, Noushin Nasiri, Sebastian Lehmann, Magdalena Ola Cichocka, Samik Mukherjee, and Kornelius Nielsch
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General Materials Science - Published
- 2022
4. Controls on the spatial and temporal patterns of rainfall‐runoff event characteristics ‐ a large sample of catchments across Great Britain
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Yanchen Zheng, Gemma Coxon, Ross Woods, Jianzhu Li, and Ping Feng
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Water Science and Technology - Published
- 2023
5. Three-Dimensional Numerical Study of Dam-Break Flood Impacting Problem with VOF Method and Different Turbulence Closures
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Ling Peng, Ting Zhang, Jianzhu Li, and Ping Feng
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Water Science and Technology ,Civil and Structural Engineering - Published
- 2023
6. A Variable Selection Method for Small Area Estimation Modeling of the Proficiency of Adult Competency
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Weijia Ren, Jianzhu Li, Andreea Erciulescu, Tom Krenzke, and Leyla Mohadjer
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adult competency ,cross-validation ,multiple data sources ,multivariate LASSO ,small area estimation - Abstract
In statistical modeling, it is crucial to have consistent variables that are the most relevant to the outcome variable(s) of interest in the model. With the increasing richness of data from multiple sources, the size of the pool of potential variables is escalating. Some variables, however, could provide redundant information, add noise to the estimation, or waste the degrees of freedom in the model. Therefore, variable selection is needed as a parsimonious process that aims to identify a minimal set of covariates for maximum predictive power. This study illustrated the variable selection methods considered and used in the small area estimation (SAE) modeling of measures related to the proficiency of adult competency that were constructed using survey data collected in the first cycle of the PIAAC. The developed variable selection process consisted of two phases: phase 1 identified a small set of variables that were consistently highly correlated with the outcomes through methods such as correlation matrix and multivariate LASSO analysis; phase 2 utilized a k-fold cross-validation process to select a final set of variables to be used in the final SAE models.
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- 2022
7. Lignin Isolated from Poplar Wood for Porous Carbons as Electrode for High-Energy Renewable Supercapacitor Driven by Lignin/Deep Eutectic Solvent Composite Gel Polymer Electrolyte
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Jinxu Huang, Yuanyuan Hu, Hao Wang, Tiansheng Wang, Hao Wu, Jianzhu Li, Yujie Li, Mi Wang, and Jiaheng Zhang
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Materials Chemistry ,Electrochemistry ,Energy Engineering and Power Technology ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering - Published
- 2022
8. Quantitative Estimation and Fusion Optimization of Radar Rainfall in Duanzhuang Watershed in the Eastern foot of Taihang Mountains
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Ting Zhang, Yi Li, Jianzhu Li, Zhixia Li, Congmei Wang, and Jin Liu
- Abstract
Rainfall data, as an important input data, its temporal and spatial resolution directly affects the accuracy of watershed hydrological simulations. Weather radar has been used in business in China, but the uncertainty of radar rainfall data is large, so the two-source rainfall data fusion based on radar and rainfall stations has become an important method to obtain rainfall data with high resolution. In this paper, taking Duanzhuang watershed in the eastern foot of Taihang Mountain for example, based on the data of 18 rainfall stations in the basin and Shijiazhuang’s S-band radar data, the radar data are preprocessed, initially optimized (overall optimization and subsection optimization) and evaluated. Then 11 rainfalls in this basin are selected by three fusion methods for fusion and quality evaluation. The results show that the pre-processed radar rainfall data and the preliminarily optimized radar rainfall data have poor effects in rainfall spatial estimation This indicates that single-source radar data cannot be directly used to describe rainfall events. Among the three fusion algorithms, the rainfall proportional coefficient fusion method (q_k method) is the best, the optimal interpolation method is the second, and the mixed geographically weighted regression-gaussian function (MGWR-GAU) fusion algorithm is the worst under the conditions of spatial and temporal variation of rainfall and different station densities. In the case of q_k method, the correlation coefficients of the three inspection stations are increased to 0.51, 0.78 and 0.82 on the point scale, and to 0.98 on the basin area scale, and the rainfall changes smoothly in time and space.It shows this method can effectively improve the data accuracy of weather radar, and it is an important fusion method to obtain high temporal and spatial resolution rainfall data in the watershed.
- Published
- 2023
9. A Framework for Estimating the Probability Distribution of Event Runoff Coefficient in Ungauged Catchments
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Yanchen Zheng, Gemma Coxon, Ross Woods, Jianzhu Li, and Ping Feng
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Water Science and Technology - Published
- 2023
10. Hierarchical Bayes small area estimation for county-level health prevalence to having a personal doctor
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Andreea Erciulescu, Jianzhu Li, Tom Krenzke, and Machell Town
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Statistics and Probability ,Statistics, Probability and Uncertainty - Published
- 2022
11. 3D Cold-Trap Environment Printing for Long-Cycle Aqueous Zn-Ion Batteries
- Author
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Hongyu Lu, Jisong Hu, Yan Zhang, Kaiqi Zhang, Xiaoying Yan, Heqi Li, Jianzhu Li, Yujie Li, Jingxin Zhao, and Bingang Xu
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science - Abstract
Zn powder (Zn-P)-based anodes are always regarded as ideal anode candidates for zinc ion battery owing to low-cost and ease of processing. However, the intrinsic negative properties of Zn-P-based anodes such as easy corrosion and uncontrolled dendrite growth have limited their further applications. Herein, a novel 3D cold-trap environment printing (3DCEP) technology is proposed to achieve the MXene and Zn-P (3DCEP-MXene/Zn-P) anode with highly ordered arrangement. Benefitting from the unique inhibition mechanism of high lattice matching and physical confinement effects within 3DCEP-MXene/Zn-P anode, it can effectively homogenize the Zn
- Published
- 2022
12. Wafer-Scale Growth of Sb
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Jun, Yang, Jianzhu, Li, Amin, Bahrami, Noushin, Nasiri, Sebastian, Lehmann, Magdalena Ola, Cichocka, Samik, Mukherjee, and Kornelius, Nielsch
- Abstract
In this work, we demonstrate the performance of a silicon-compatible, high-performance, and self-powered photodetector. A wide detection range from visible (405 nm) to near-infrared (1550 nm) light was enabled by the vertical p-n heterojunction between the p-type antimony telluride (Sb
- Published
- 2022
13. Evaluation and tradeoff‐synergy analysis of ecosystem services in Luanhe River Basin
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Xiangrong Feng, Ting Zhang, Ping Feng, and Jianzhu Li
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Ecology ,Aquatic Science ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Published
- 2022
14. Optimal designs of LID based on LID experiments and SWMM for a small-scale community in Tianjin, north China
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Boyuan Yang, Ting Zhang, Jianzhu Li, Ping Feng, and Yuanjingjing Miao
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Environmental Engineering ,General Medicine ,Management, Monitoring, Policy and Law ,Waste Management and Disposal - Published
- 2023
15. Event-based and continous flood modeling in Zijinguan watershed, Northern China
- Author
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Chunqi Hu, Rajeev Katwal, Jianzhu Li, Muhammad Akbar Rafique, Yanchen Zheng, and Ting Zhang
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Hydrology ,021110 strategic, defence & security studies ,Atmospheric Science ,Watershed ,010504 meteorology & atmospheric sciences ,0211 other engineering and technologies ,Hydrograph ,02 engineering and technology ,Runoff curve number ,01 natural sciences ,Evapotranspiration ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,Water cycle ,HEC-HMS ,Surface runoff ,Flow routing ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
Hydrological models are a conceptual representation of a simplified hydrological cycle. The hydrological cycle is the water cycle that circulates water from the land surface to the atmosphere and back again to the land. With the use of Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS), an event-based model and a continous hydrological model were established in Zijinguan watershed of Daqinghe River basin. To study the loss methods provided by HEC-HMS and its appropriateness for model fitting, is the main objective of this paper. The watershed was delineated with HEC-GeoHMS in ArcGIS, and its properties were extracted from a Digital Elevation Model (DEM) of 30 m × 30 m. The HEC-HMS includes a soil conservation service curve number (SCS-CN) method and a soil moisture calculation (SMA) loss method, simulating the event and continuous runoff, respectively. SCS Unit hydrograph and Muskingum were used for flow routing. Specifically, eight rainfall events were selected for calibrating (6 events) and verifying (2 events) the event-based model. Similarly, for the continuous model the wet seasons of eight different years were used for calibration and verification. The calibrated parameters of the events model were used in the continuous model. The soil moisture and evapotranspiration data were decoded from the satellite data to set in the continuous model. The performance of SCS-CN and SMA models was compared. During the calibration period, the values of NSE, PEV and PEPF range from 0.605 to 0.744, 3.1 to 13.58%, and 11.104 to 27.72%, and during validation they are 0.527 to 0.634, 4.35% to 5.01%, and 13.66% to 27.88%, for SCS-CN model. For the SMA model, the values of NSE, PEV and PEPF during calibration range from 0.434 to 0.604, 2.879 to 34.326%, −4.831 to 57.48%, and during validation they are 0.094 to 0.624, −19.52% to −12.55%, and 40.213% to 50.15%. Overall, the performance of SCS-CN model is found more satisfactory than that of SMA model.
- Published
- 2021
16. Numerical simulation study of urban hydrological effects under low impact development with a physical experimental basis
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Lidong Zhao, Ting Zhang, Jianzhu Li, Libin Zhang, and Ping Feng
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Water Science and Technology - Published
- 2023
17. 3D Cold‐Trap Environment Printing for Long‐Cycle Aqueous Zn‐Ion Batteries (Adv. Mater. 9/2023)
- Author
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Hongyu Lu, Jisong Hu, Yan Zhang, Kaiqi Zhang, Xiaoying Yan, Heqi Li, Jianzhu Li, Yujie Li, Jingxin Zhao, and Bingang Xu
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science - Published
- 2023
18. Lattice vibrational characteristics and dielectric properties of pure phase CaTiO3 ceramic
- Author
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Jianzhu Li, Feng Shi, Guang-en Fu, and En-Cai Xiao
- Subjects
010302 applied physics ,Materials science ,Condensed matter physics ,Rietveld refinement ,Sintering ,Infrared spectroscopy ,Dielectric ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,symbols.namesake ,visual_art ,Molecular vibration ,0103 physical sciences ,visual_art.visual_art_medium ,symbols ,Grain boundary ,Ceramic ,Physics::Chemical Physics ,Electrical and Electronic Engineering ,Raman spectroscopy - Abstract
CaTiO3 microwave dielectric ceramic was fabricated utilizing traditional two-step sintering process. XRD pattern analysis after Rietveld refinement indicated a pure phase CaTiO3 sample. SEM image illustrated well-crystallized sample with uniform grain sizes and clear grain boundaries. The lattice vibrational characteristics were analyzed by Raman and IR spectroscopy, and the intrinsic properties were calculated in conjunction with the semi-quantum four-parameter (FPSQ) model, which turned out that the low-frequency vibrational modes contribute the most to the dielectric properties. Besides, the real and imaginary parts of the dielectric function were drawn from the FPSQ model. The intrinsic property results fitted from the FPSQ model agree well with the measured values.
- Published
- 2020
19. Drought severity classification based on threshold level method and drought effects on NPP
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Fulong Chen, Keke Zhou, and Jianzhu Li
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Hydrology ,Atmospheric Science ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,0207 environmental engineering ,Drainage basin ,02 engineering and technology ,Structural basin ,01 natural sciences ,Agricultural land ,Environmental science ,020701 environmental engineering ,Primary productivity ,0105 earth and related environmental sciences - Abstract
Threshold level method is well-known for drought identification with the advantage of its simplicity. However, there is no criterion for classification of drought classes in this method. Therefore, a K index based on threshold level method was proposed and verified to perform well in drought assessment in the Luanhe River basin, China. Meteorological data and remote sensing data were used to calculate the net primary productivity (NPP) of the basin by the CASA model. Results showed that the model had a good performance in comparison with the downloaded yearly remote sensing NPP and monthly PsnNet. The NPP in the basin tended to increase slowly during the year of 2000–2010, and the NPP in the downstream was generally larger than upstream. In three selected representative drought years, drought reduced NPP by about 15–25%, and during the growth season, drought may reduce NPP by about 4.6%, 2.7%, and 1.9% in July, August, and September, respectively, due to reduced precipitation. NPP on grasslands and agricultural land were more susceptible to drought than forests. The result of gray incidence analysis showed that the effects of drought on NPP had a certain delay with about 5 months.
- Published
- 2020
20. Estimation of Initial Abstraction for Hydrological Modeling Based on Global Land Data Assimilation System–Simulated Datasets
- Author
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Ping Feng, Yanchen Zheng, Aiqing Kang, Jianzhu Li, Youtong Rong, and Lixin Dong
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Estimation ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Meteorology ,Artificial neural network ,Hydrological modelling ,0207 environmental engineering ,02 engineering and technology ,01 natural sciences ,Data assimilation ,Environmental science ,Water cycle ,020701 environmental engineering ,Surface runoff ,0105 earth and related environmental sciences ,Abstraction (linguistics) - Abstract
Initial abstraction (Ia) is a sensitive parameter in hydrological models, and its value directly determines the amount of runoff. Ia, which is influenced by many factors related to antecedent watershed condition (AWC), is difficult to estimate due to lack of observed data. In the Soil Conservation Service curve number (SCS-CN) method, it is often assumed that Ia is 0.2 times the potential maximum retention S. Yet this assumption has frequently been questioned. In this paper, Ia/S and factors potentially influencing Ia were collected from rainfall–runoff events. Soil moisture and evaporation data were extracted from GLDAS-Noah datasets to represent AWC. Based on the driving factors of Ia, identified using the Pearson correlation coefficient and maximal information coefficient, artificial neural network (ANN)-estimated Ia was applied to simulate the selected flood events in the Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) model. The results indicated that Ia/S varies over different events and different watersheds. Over 75% of the Ia/S values are less than 0.2 in the two study areas. The driving factors affecting Ia vary over different watersheds, and the antecedent precipitation index appears to be the most influential factor. Flood simulation by the HEC-HMS model using statistical Ia gives the best fitness, whereas applying ANN-estimated Ia outperforms the simulation with median Ia/S. For over 60% of the flood events, ANN-estimated Ia provided better fitness in flood peak and depth, with an average Nash–Sutcliffe efficiency coefficient of 0.76 compared to 0.71 for median Ia/S. The proposed ANN-estimated Ia is physically based and can be applied without calibration, saving time in constructing hydrological models.
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- 2020
21. The Effect of Nonstationarity in Rainfall on Urban Flooding Based on Coupling SWMM and MIKE21
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Shuai Li, Jianzhu Li, Ping Feng, Aiqing Kang, and Linhan Yang
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Return period ,Hydrogeology ,010504 meteorology & atmospheric sciences ,Flood myth ,Environmental change ,0208 environmental biotechnology ,Generalized additive model ,Flooding (psychology) ,02 engineering and technology ,01 natural sciences ,020801 environmental engineering ,Climatology ,Environmental science ,Precipitation ,Scale (map) ,0105 earth and related environmental sciences ,Water Science and Technology ,Civil and Structural Engineering - Abstract
The characteristics of urban pluvial flooding are altering all over the world due to environmental change. In this paper, generalized additive models for location, scale and shape (GAMLSS) was employed to analyze nonstationary frequency of extreme precipitation at subdaily scale. Nonstationary precipitation return periods were estimated using the expected waiting time (EWT) interpretation. A model coupling SWMM and MIKE21 was established, and calibrated and verified by three historical urban floods. Then, it was utilized to simulate urban floods under stationary and nonstationary rainfall conditions with different return periods. The simulated results illustrated that rainfall depth under nonstationarity was greater than that of stationarity when return period was less than 10 years, but the results reversed when the return period was over 20 years. The main variation of rainfall depth occurred within 6 h. The deviation of the maximum water depth was less than 10% for five return levels, and the difference in the longest inundation lengths was 1.2 h for 50-year return period under two assumptions. It may indicate that slight differences of urban flooding were detected between stationary and nonstationary conditions in the study region, which suggested a further study about urban flood under nonstationarity.
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- 2020
22. Response of ecosystem gross primary productivity to drought in northern China based on multi-source remote sensing data
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Ting Zhang, Junzhi Zhou, Ping Yu, Jianzhu Li, Yanfu Kang, and Bo Zhang
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Water Science and Technology - Published
- 2023
23. Crystal structure, dielectric properties, and lattice vibrational characteristics of LiNiPO 4 ceramics sintered at different temperatures
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Zhenxing Yue, Xue-hui Li, Zhikai Cao, Ying Chen, Huanfu Zhou, En-Cai Xiao, Feng Shi, Jianzhu Li, Kaixin Song, Guohua Chen, and Mengting Liu
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Materials science ,Condensed matter physics ,Lattice (order) ,visual_art ,Materials Chemistry ,Ceramics and Composites ,visual_art.visual_art_medium ,Crystal structure ,Dielectric ,Ceramic - Published
- 2019
24. Analysis of flood peak scaling in mesoscale non-nested basin
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Ping Feng, Jianzhu Li, Qiushuang Ma, Keke Zhou, and Ting Zhang
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010504 meteorology & atmospheric sciences ,Flood myth ,Climatology ,0208 environmental biotechnology ,Mesoscale meteorology ,02 engineering and technology ,Structural basin ,01 natural sciences ,Scaling ,Geology ,020801 environmental engineering ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
The study of flood scaling is an important means to solve the problem of flood prediction in ungauged and poorly gauged basins. With the impact of climate change and human activities, the mechanism and process of floods are constantly changing. However, in many areas, there are only simple scaling results that can be used to guide daily work. Taking the Daqinghe River basin as an example, a fixed flood scaling exponent determined in 1974 (before the change point of 1979) is still used all over the basin, which is apparently no longer appropriate. Therefore, in this paper, we aim to explore: (1) the scale relationship between the peak flows and the basin area under changing environments; (2) the validation of the scale invariance theory; (3) the physical relationship between the event-based scaling theory and the annual flood quantile-based scaling theory in the mesoscale non-nested and partly nested basins; and (4) the modification of the existing uniform flood scaling exponent in the study area. To achieve these objectives, eight simultaneous observed flood events in seven non-nested and partly nested mesoscale sub-basins of the Daqinghe River basin were selected to analyze the flood scaling theory. The results showed that there was a scaling relationship between the flood peaks and watershed area for the flood events, and the scale invariance theory was also supported herein. To analyze the effect of the environmental conditions on flood scaling in the Daqinghe River basin, the flood events were reconstructed after the change point (the year 1979). It was found that the flood scaling exponents of the reconstructed flood events are larger than those of the observed events after the change point. The flood scaling exponent changed with flood events, varying from 0.65 to 1.26 when considering the basin area as the independent variable, and decreasing with a minimum of 0.36 when taking the rainfall characteristics into consideration. It was also found that the mean of the event-based scaling exponents is larger than the annual flood quantile-based scaling exponents.
- Published
- 2019
25. Evaluation of multi-satellite precipitation products in estimating precipitation extremes over mainland China at annual, seasonal and monthly scales
- Author
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Yuefen Zhang, Chuanhao Wu, Pat J.-F. Yeh, Jianzhu Li, Bill X. Hu, Ping Feng, and Yong Lei
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Atmospheric Science - Published
- 2022
26. Effect of Microstructural Evolution on Mechanical Properties and Fracture Modes of AlSi10Mg Blocks Fabricated by Selective Laser Melting after Stress Relief Annealing
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Jianzhu Li, Yujie Li, Zhe Wang, Changguang Li, Hai Yuan, and Yun Hao
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General Materials Science ,Condensed Matter Physics - Published
- 2022
27. Hydrological Drought Forecasting Incorporating Climatic and Human-Induced Indices
- Author
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Ping Feng, Jianzhu Li, Min Li, and Ting Zhang
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,Climatology ,0207 environmental engineering ,Climate change ,Environmental science ,Hydrometeorology ,02 engineering and technology ,020701 environmental engineering ,01 natural sciences ,0105 earth and related environmental sciences - Abstract
Many drought forecasting methods have been proposed, but only a few have considered the changing environment. The main purpose of this study is to improve the accuracy of drought forecasting models under changing environments by considering the influence of large-scale climate patterns and human activities on hydrological drought. To select the most significant large-scale climatic index that influences drought events in the Luanhe River basin, Spearman’s rho correlation test was applied to detect the relationship between large-scale oceanic–atmospheric circulation patterns and the standardized runoff index (SRI). We also proposed a human activity index (HI) to represent the effect of human activities on hydrological drought. Based on a multivariate normal distribution, we included the above indices in a probabilistic forecasting model, which forecasted the probabilities of transition from the current to a future SRI value. Using the Liying hydrological station as an example, the impacts of a controlled large-scale climatic index (Niño-3.4) and the HI on the transition probabilities were illustrated, and the results showed that the turning point of the Niño-3.4 effect on the transition probabilities occurred within the range from 25.91 to 26.90. Finally, a scoring method was applied to compare the forecasting model performances. The results showed that the inclusion of the large-scale climatic index and HI improved the forecasting accuracy.
- Published
- 2019
28. Flood scaling under nonstationarity in Daqinghe River basin, China
- Author
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Ping Feng, Ting Zhang, Qiushuang Ma, Yuming Lei, Yu Tian, and Jianzhu Li
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Return period ,021110 strategic, defence & security studies ,Atmospheric Science ,Stationary process ,010504 meteorology & atmospheric sciences ,Flood myth ,Generalized additive model ,0211 other engineering and technologies ,Climate change ,02 engineering and technology ,01 natural sciences ,Natural hazard ,Climatology ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,Scaling ,0105 earth and related environmental sciences ,Water Science and Technology ,Quantile - Abstract
Flood scaling issue is usually studied under stationary conditions. However, in recent decades, climate change and anthropogenic activities have changed hydrological processes, and stationary assumption has been questioned. To test the flood scaling invariance (simple scaling or multiscaling) and analyze the influence of environmental change on flood scaling parameter, in this study, eight mesoscale sub-watersheds in Daqinghe River basin were selected as the study area, and the trend and change point of annual maximum flood peak (AMFP) series were detected, respectively. All the AMFP series had downward trend, and the change point was around 1979. Therefore, the AMFP series are nonstationary. To analyze the flood scaling issue in the Daqinghe River basin, the AMFP series were reconstructed under the environmental conditions before and after the change point, respectively. Then, flood quantiles were calculated using the reconstructed stationary series. We also used GAMLSS (Generalized Additive Model in Location, Scale and Shape) to calculate flood quantiles based on the observed nonstationary AMFP series. According to the flood quantiles calculated by the above methods, the relationship of the drainage areas of the sub-watersheds and the flood quantiles was fitted with power function. Flood quantiles of the reconstructed stationary and observed nonstationary series showed obvious flood multiscaling. The increase in rainfall depth causes the increase in flood scaling exponents with the increase in return period, and different change ratios of land use before and after change point resulted in the flood scaling exponents of reconstructed series before 1979 were smaller than those after the change point at same return period.
- Published
- 2019
29. Preparations, properties and applications of low-dimensional black phosphorus
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Feng Shi, Jiayi Jing, Jianzhu Li, Chao Xing, and Juhui Zhang
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Electron mobility ,Materials science ,Fabrication ,General Chemical Engineering ,Transistor ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Exfoliation joint ,Industrial and Manufacturing Engineering ,Black phosphorus ,0104 chemical sciences ,law.invention ,law ,Environmental Chemistry ,Degradation (geology) ,Direct and indirect band gaps ,0210 nano-technology ,Anisotropy - Abstract
Black phosphorus (BP) with a layered structure is the most stable allotrope of phosphorus, which was first prepared under high pressure in 1914. Since the development of a field-effect transistor with BP in 2014, BP has drawn interest, exhibiting numerous superior properties, such as distinct pleated structures in layers, an adjustable direct band gap, high carrier mobility, and many interesting in-layer anisotropies. This review summarizes the latest preparation techniques, properties, and applications of low-dimensional BP. Methods for the fabrication of two-dimensional BP include mechanical exfoliation, electrochemical assistance, and liquid exfoliation. The last method can also produce BPQDs by changing the process. In numerous excellent physical properties of BP, this review emphasizes its distinct anisotropy, including mechanical, thermally conductive, optical anisotropy, and so on. The potential uses of low-dimensional BP, involving field-effect transistors, photodetectors, catalysts, as well as photothermal therapeutic agents, are introduced in detail. The last application listed is closely associated with the health of human beings. To improve the stability of BP, its degradation mechanism with several fruitful protection methods is elaborated. Finally, the shortcomings in current research are discussed, and suggestions and prospects are proposed for the future research on low-dimensional BP.
- Published
- 2019
30. Changes in flood characteristics and the flood driving mechanism in the mountainous Haihe River Basin, China
- Author
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Ping Feng, Jiezhao Wu, and Jianzhu Li
- Subjects
Hydrology ,Driving factors ,geography ,geography.geographical_feature_category ,Flood myth ,Land use ,Hydrological modelling ,0208 environmental biotechnology ,Flooding (psychology) ,Drainage basin ,02 engineering and technology ,Structural basin ,020801 environmental engineering ,Hydrology (agriculture) ,Environmental science ,Water Science and Technology - Abstract
Recently, the land surface in the Haihe River basin has changed, influencing the flood processes in the basin. To quantify this impact, seven typical sub-catchments were selected from different hyd...
- Published
- 2019
31. Changes in drought propagation under the regulation of reservoirs and water diversion
- Author
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Bing Wang, Yixuan Wang, Ting Zhang, and Jianzhu Li
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Driving factors ,Hydrology ,Atmospheric Science ,geography ,Resource (biology) ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,0207 environmental engineering ,Drainage basin ,02 engineering and technology ,01 natural sciences ,Water diversion ,Water resources ,Lag time ,Environmental science ,SWAT model ,020701 environmental engineering ,0105 earth and related environmental sciences - Abstract
Drought propagation is very significant for short-term drought forecast and water resources management. However, the law of drought propagation is still unclear, especially with human activities. In this study, we calibrated and validated the SWAT model in the Luanhe River basin controlled by the Luanxian hydrological station, where there are three large reservoirs upstream and water diversion to Tianjin city. The variable threshold level (VTL) method was employed to identify meteorological and hydrological events both under natural and reservoir-influenced conditions. Drought occurred more frequently, drought duration became longer, and drought deficit became larger with the influence of reservoir regulation and water diversion to Tianjin city. The lag time of hydrological drought onset was shorter and termination longer, i.e., the drought period was more persistent. Multiple regression was used to establish the relations between hydrological drought and the driving factors both under natural and reservoir-influenced conditions. The coefficient of determination is high enough to explain drought propagation. The driving factors were different under the two conditions. The results could provide valuable information for water resource managers.
- Published
- 2019
32. Replicating Published Data Tables to Assess Sensitivity in Subsequent Analyses and Mapping
- Author
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Jianzhu Li and Tom Krenzke
- Subjects
business.industry ,Pattern recognition ,General Medicine ,Sensitivity (control systems) ,Artificial intelligence ,business ,Mathematics - Published
- 2019
33. Intrinsic dielectric properties and vibration characteristics of La(Mg1/2Sn1/2)O3 ceramic
- Author
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Huiling Chen, Jianzhu Li, Xunqian Yin, Hengyang Qiao, Jing Wang, Feng Shi, and Chao Xing
- Subjects
Diffraction ,Materials science ,02 engineering and technology ,Dielectric ,010402 general chemistry ,01 natural sciences ,Condensed Matter::Materials Science ,symbols.namesake ,Polarizability ,lcsh:TA401-492 ,Ceramic ,Condensed matter physics ,Metals and Alloys ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Molecular vibration ,visual_art ,symbols ,visual_art.visual_art_medium ,lcsh:Materials of engineering and construction. Mechanics of materials ,Dielectric loss ,0210 nano-technology ,Raman spectroscopy ,Raman scattering - Abstract
La(Mg1/2Sn1/2)O3 (LMS) ceramic was synthesized via the conventional solid-state reaction method. The main phase of the sample is LMS with a double perovskite structure (monoclinic P121/n1 symmetry), which is confirmed by X-ray diffraction. Scanning electron microscopy shows the sample is well-crystallized with dense and uniform grains as well as clear grain boundaries. The Raman scattering and Fourier transform far-infrared reflection spectroscopies were employed to analyze the lattice vibrational modes of the sample. The Raman active modes were fitted by the Lorentz function, and the lattice vibrational modes were assigned and illustrated accurately. The four-parameter semiquantum model was applied to simulate the intrinsic dielectric properties, which agree well with the data calculated from the microscopic polarizability & damping angles. The A1g(La) Raman mode in A-site has a great impact on the dielectric loss, and F3u(2) mode makes the largest contribution to the dielectric constant and the dielectric loss. Keywords: Microwave dielectric ceramic, Double perovskite, Crystal structures, Intrinsic dielectric properties, Vibration characteristics
- Published
- 2019
34. Three-dimensional identification of hydrological drought and multivariate drought risk probability assessment in the Luanhe River basin, China
- Author
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Jianzhu Li, Ping Feng, Xu Chen, and Fawen Li
- Subjects
Atmospheric Science ,Multivariate statistics ,010504 meteorology & atmospheric sciences ,Soil and Water Assessment Tool ,0207 environmental engineering ,02 engineering and technology ,Bivariate analysis ,01 natural sciences ,Copula (probability theory) ,Gumbel distribution ,Joint probability distribution ,Statistics ,SWAT model ,Marginal distribution ,020701 environmental engineering ,0105 earth and related environmental sciences ,Mathematics - Abstract
It is critical to assess drought risk probability based on a really spatio-temporal continuum identification and characterization method, which is of great importance for drought resistance, planning, and management of water resource as well as agricultural production. Therefore, the major motivation of this study is to identify and characterize hydrological drought events in a three-dimensional framework and further assess the potential drought risk probability in a multivariate framework in the Luanhe River basin during 1961–2011. The study adopts a really spatio-temporal continuum identification method to characterize drought, and copula functions for multivariate risk probability assessment of hydrological drought. First, the Soil and Water Assessment Tool (SWAT) model is used to simulate the watershed runoff and the cubic spline interpolation method is used to obtain the gridded data sets. Second, the Standardized Runoff Index (SRI) and the three-dimensional identification method are employed to identify hydrological drought. Third, according to three drought parameters of drought severity (S), duration (D), and affect area (A), the marginal distribution, bivariate, and trivariate joint distribution are constructed, and the optimal ones are selected based on different evaluation methods of goodness-of-fit. Fourth, based on the derived marginal and joint distributions, drought risk probability is fully assessed. Results indicate that: (1) SWAT model is a reliable tool to simulate the watershed hydrologic processes; (2) the three-dimensional identification method used in this study is robust and efficient; (3) the optimal marginal distributions for S, D, and A are GEV, GEV, and lognormal distribution; the optimal bivariate copula function for S-D, S-A, and D-A are Joe, Gumbel, and Joe copula; and the optimal trivariate copula function for S-D-A is Nested Gumbel copula; (4) return periods of the first five most serious drought events are 80, 75, 46, 45, and 40 years, respectively; (5) to completely characterize the spatio-temporal variability of hydrological drought, it is necessary to completely consider the three characteristic variables of S, D, and A.
- Published
- 2019
35. Water supply risk analysis of Panjiakou reservoir in Luanhe River basin of China and drought impacts under environmental change
- Author
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Ting Zhang, Peizhen Ren, Zhenxing Gao, Ping Feng, Jianzhu Li, and Yuangang Guo
- Subjects
Atmospheric Science ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Environmental change ,business.industry ,0207 environmental engineering ,Drainage basin ,Water supply ,02 engineering and technology ,01 natural sciences ,Water level ,Environmental Sustainability Index ,Streamflow ,Environmental science ,020701 environmental engineering ,China ,business ,Surface runoff ,Water resource management ,0105 earth and related environmental sciences - Abstract
This study investigates the impacts of drought on water supply risk of Panjiakou reservoir in Luanhe River basin of China under environmental change by using a copula-based streamflow series generation approach. To understand how nonstationarity of runoff sequence influences water supply risk, reservoir performance metrics including reliability (time-based and volume-based), resilience, vulnerability, drought risk index (DRI), and sustainability index (SUI) are evaluated with 1956–1979 and 1980–2016 inflows of Panjiakou reservoir, respectively. The results indicated that the prolonged and severe drought may seriously affect the safety of water supply. From two results of generated streamflow time series, the reliability reduction rate reached 58.3% (0.773 to 0.322) when water supply assurance rate was 75% and ecological water level was minimum. Perturbing the copula parameter will make it possible to increase the drought durations and deficits for Panjiakou reservoir to analyze drought impacts on water supply. Based on the reservoir performance metrics, the analysis for Panjiakou reservoir showed that the trend of drought in the future made water supply reliability (time-based and volume-based), resilience, and SUI decrease, but vulnerability and DRI increase, which means the water supply system security became more vulnerable in the future. These results make it easy for decision makers to understand how drought influences future planning and management of Panjiakou reservoir.
- Published
- 2019
36. Phonon characteristics and dielectric properties of BaMoO4 ceramic
- Author
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Jianzhu Li, Mei Guo, Ze-Ming Qi, Hengyang Qiao, Feng Shi, Jing Wang, Gang Dou, En-Cai Xiao, Qing Wang, and Chao Xing
- Subjects
010302 applied physics ,Permittivity ,Diffraction ,Materials science ,Condensed matter physics ,Phonon ,Scanning electron microscope ,Metals and Alloys ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Tetragonal crystal system ,symbols.namesake ,visual_art ,0103 physical sciences ,lcsh:TA401-492 ,visual_art.visual_art_medium ,symbols ,lcsh:Materials of engineering and construction. Mechanics of materials ,Ceramic ,0210 nano-technology ,Raman spectroscopy - Abstract
BaMoO4 ceramic was prepared using a conventional solid-sintering method. It was observed that the sample is a pure BaMoO4 with a tetragonal scheelite structure by analyzing X-ray diffraction data. Scanning electron microscopy characterized the dense sample with uniform grains. The phonon modes were analyzed by Raman and Far-infrared reflection spectra, and the phonon characteristics were studied. The intrinsic properties of the sample were calculated by the four-parameter semi-quantum model as well as the Clausius-Mosotti & damping equations, and the results were of εr = 9.388 and tanδ = 4.760 × 10−4, εr = 9.798 and tanδ = 6.445 × 10−4, respectively, which agrees well with the experimental values (εr = 9.84, tanδ = 5.0 × 10−4). The contributions to dielectric properties of each mode were investigated, and the results indicate that the external mode (Eu) yield greatest contribution to intrinsic permittivity and loss. Keywords: Microwave dielectric ceramic, BaMoO4, Crystal structure, Dielectric properties, Phonon characteristics
- Published
- 2018
37. The influence of soil moisture conditions on the spatio-temporal variability of event rainfall-runoff coefficients in UK catchments
- Author
-
Feng Ping, Ross Woods, Yanchen Zheng, and Jianzhu Li
- Subjects
Hydrology ,Rainfall runoff ,Event (relativity) ,Environmental science ,Water content - Abstract
Since the bias and uncertainties of the current design flood estimation methods for ungauged catchments are inevitable, estimation of the design flood in ungauged catchments still remains an unsolved problem. The derived distribution approach appears to be the one of the promising design flood estimation methods, as this method can improve the understanding on which processes contribute most to flood in ungauged catchments. Generally, the distribution of rainfall characteristics and lumped rainfall-runoff modelling was incorporated to estimate the flood magnitude in this method. However, we should note that rainfall is not the only driving factor of flood events. Soil moisture conditions are also an important driving factor affecting the rainfall-runoff transformation, and may even control rainfall-runoff coefficients to a higher degree than does rainfall. Hence, here we perform soil moisture analysis at national scale by employing GLDAS-Noah datasets, and link this to observed event runoff coefficients from a large sample of UK catchments. The relationship between soil moisture conditions and rainfall-runoff coefficient was explored to analyse the spatio-temporal variability of runoff coefficient. This study laid the foundation for further development of a practical derived distribution method, by considering the statistical distribution of rainfall-runoff coefficients and the influence of soil moisture conditions.
- Published
- 2021
38. Multi‐Component Crosslinked Hydrogel Electrolyte toward Dendrite‐Free Aqueous Zn Ion Batteries with High Temperature Adaptability
- Author
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Hongyu Lu, Jisong Hu, Litong Wang, Jianzhu Li, Xiang Ma, Zhicheng Zhu, Heqi Li, Yingjie Zhao, Yujie Li, Jingxin Zhao, and Bingang Xu
- Subjects
Biomaterials ,Electrochemistry ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
39. Evaluation and comparison of precipitation estimates and hydrologic utility of CHIRPS, TRMM 3B42 V7 and PERSIANN-CDR products in various climate regimes
- Author
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Yuefen Zhang, Pat J.-F. Yeh, Jianzhu Li, Bill X. Hu, Ping Feng, Chuanhao Wu, and Changhyun Jun
- Subjects
Atmospheric Science ,Coefficient of determination ,Climatology ,PERSIANN ,Environmental science ,Satellite ,Tropical rainfall ,Precipitation ,Spatial extent - Abstract
Evaluation of satellite-based quantitative precipitation estimates (QPEs) with reliable and independent ground-based measurements is important for both product developers and users. Here, we present a comprehensive evaluation on 3 high-resolution QPEs, namely, the Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS), the latest non-real-time post-processing version of Tropical Rainfall Measuring Mission (TRMM 3B42 V7), and the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR), in 3 basins with different climates in China. The accuracy of 3 QPEs in reproducing the spatial extent of daily and monthly precipitation (PR) as well as extreme PR indices was evaluated. Two simulation scenarios were utilized to evaluate the efficiency of hydrologic events forecasting of these 3 QPEs quantitatively. The results indicated that the 3 QPEs generally show high accuracy in estimating monthly PR in 3 basins, among which TRMM 3B42 V7 performs best (coefficient of determination R2
- Published
- 2022
40. Nonstationary Flood Frequency Analysis for Annual Flood Peak and Volume Series in Both Univariate and Bivariate Domain
- Author
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Yuming Lei, Colin D. Bell, Jianzhu Li, Yixuan Wang, Senming Tan, and Bernard A. Engel
- Subjects
Multivariate statistics ,Flood myth ,0208 environmental biotechnology ,Copula (linguistics) ,Univariate ,02 engineering and technology ,Bivariate analysis ,020801 environmental engineering ,Joint probability distribution ,Statistics ,Marginal distribution ,Water Science and Technology ,Civil and Structural Engineering ,Mathematics ,Weibull distribution - Abstract
Flood frequency analysis for practical application is traditionally based on the assumption of stationarity, but this assumption has been open to doubt in recent years. A number of studies have focused on the nonstationary flood frequency analysis, and the associated causes of nonstationarity. In this study, the annual maximum flood peak and flood volume of Wangkuai reservoir watershed were used, and several univariate and bivariate models were established to investigate the nonstationary flood frequency, with the distribution parameters changing over the climate indices (NPO, Nino3) and the check dam indices (CDIp, CDIv). In the univariate models, the Weibull distribution performed best and exhibited an undulate behavior for both flood peak and volume, which tended to describe the nonstationarity reasonably well. The bivariate models were constructed using copulas, of which the optimal Weibull distribution in the univariate flood frequency analysis was considered as marginal distributions within the joint distribution. The results showed that the Gumbel-Hougaard copula offered the best joint distribution, and most of the probability isolines crossed each other, which demonstrated the possibility that the occurrence of combinations of the flood peak and volume may be the same under multiple effects of phase changes in the climate patterns and certain human activities (i.e. soil and water conservation). The most likely events were elaborated in diagrams, and the associated combinations of the flood peak and volume were smaller than that estimated by the fixed parameters (i.e. stationary condition) during most of the study period, while it was the opposite in 1956, 1959 and 1963. The results highlight the necessity of nonstationary flood frequency analysis under various conditions in both univariate and multivariate domains.
- Published
- 2018
41. Correlation between vibrational modes, crystal structures, and dielectric properties of (1 − x)Ba(Mg1/3Ta2/3)O3–xBa(Co1/3Nb2/3)O3 ceramics
- Author
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Liang Fang, Feng Shi, Qing Wang, Jianzhu Li, Chao Xing, Hengyang Qiao, Guoxiang Zhao, Qi Ze-Ming, and Huiling Chen
- Subjects
010302 applied physics ,Materials science ,Infrared ,Scattering ,Phonon ,Mechanical Engineering ,Analytical chemistry ,02 engineering and technology ,Dielectric ,Crystal structure ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Full width at half maximum ,symbols.namesake ,Mechanics of Materials ,Molecular vibration ,0103 physical sciences ,symbols ,General Materials Science ,0210 nano-technology ,Raman spectroscopy - Abstract
(1 −x) Ba(Mg1/3Ta2/3)O3–x Ba(Co1/3Nb2/3)O3 (BMT–BCN, x = 0.0, 0.20, 0.25, 0.30, 0.40) ceramics were prepared using the traditional solid-state reaction method. X-ray diffraction patterns have shown that the intensities of (001) and (100) super-lattices decrease with the increase in the BCN content. Seven main Raman vibrational modes are observed, assigned, and illustrated, in particular. Raman shifts of Eg(O) modes and the FWHM values of F2g(O)/A1g(O) modes have close relationship with the dielectric properties. The calculated values by the four-parameter semiquantum model based on IR reflectivity match well with the measured data (@3.8 GHz), which means that most of dielectric contribution to the system may be ascribed to the absorption of structural phononic oscillations at the infrared region, and the contribution from the scattering of the defective phonons is small. The contributions of each vibrational mode on the dielectric responses were investigated in detail, indicating that the low-frequency modes (A2u(1) and Eu(1)) have a decisive role to the dielectric properties.
- Published
- 2018
42. Internal Relations between Crystal Structures and Intrinsic Properties of Nonstoichiometric Ba1+xMoO4 Ceramics
- Author
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Xunqian Yin, Jianzhu Li, Chao Xing, Qing Wang, Huiling Chen, Feng Shi, Jing Wang, Hengyang Qiao, and Zeming Qi
- Subjects
010302 applied physics ,Diffraction ,Chemistry ,Rietveld refinement ,Analytical chemistry ,Sintering ,02 engineering and technology ,Dielectric ,Crystal structure ,021001 nanoscience & nanotechnology ,Atomic packing factor ,01 natural sciences ,Spectral line ,Inorganic Chemistry ,symbols.namesake ,0103 physical sciences ,symbols ,Physical and Theoretical Chemistry ,0210 nano-technology ,Raman spectroscopy - Abstract
Ba1+ xMoO4 (-0.03 ≤ x ≤ 0.03) ceramics were fabricated by a conventional two-step sintering technique. X-ray diffraction patterns show that there appeared new diffraction peaks when x > 0, which were identified as Ba2MoO5. The Rietveld refinement results indicate that the unit cell volume is the largest at x = -0.02, because it has the lowest packing fraction and covalency. The far-infrared reflectivity (IR) spectra were fitted and analyzed for calculating the intrinsic properties, which comply well with the data obtained from microscopic polarizabilities and damping coefficient angle. The proportion of each mode in the dielectric response demonstrates that the Ba-O8 polyhedra have a decisive role on the dielectric properties. And based on the Raman modes, the internal relations of the structural-properties were revealed with the changes of Ba2+ content.
- Published
- 2018
43. Crystal structure, phonon characteristic, and intrinsic properties of Sm(Mg1/2Sn1/2)O3 double perovskite ceramic
- Author
-
Helei Dong, Jianzhu Li, Hengyang Qiao, Feng Shi, Ze Ming Qi, Huiling Chen, Jun Yang, Chao Xing, Qingkun He, Haiqing Sun, and Jing Wang
- Subjects
010302 applied physics ,Permittivity ,Materials science ,Phonon ,Analytical chemistry ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,symbols.namesake ,Molecular vibration ,0103 physical sciences ,symbols ,Dielectric loss ,Electrical and Electronic Engineering ,0210 nano-technology ,Raman spectroscopy ,Raman scattering ,Perovskite (structure) - Abstract
Sm(Mg1/2Sn1/2)O3(SMS) microwave dielectric ceramic was prepared by the traditional solid state synthesis method. The samples were tested by X-ray diffraction (XRD), vibrational spectra (Raman scattering and far-infrared reflectance spectroscopy). The Sm(Mg1/2Sn1/2)O3 perovskite is monoclinic with the space group P21/n proved by XRD. Raman vibrational modes were fitted and assigned by Lorentz function. To calculate the intrinsic properties, far-infrared spectra with seven active modes were fitted using a four-parameter semi-quantitative (FPSQ) model. The dielectric constant calculated according to FPSQ is similar to that obtained from the molecular polarization and the Clausius equation. The intrinsic loss has been determined by the relationship between the damping factor and the spectral center frequency, which is slightly larger than the value obtained in the four-parameter fitting, and indicates that A1g(Sm) Raman mode has a enormous effect on the dielectric loss. F3u (3) and F4u (4) have the greatest contribution to the dielectric constant and loss. Finally, the real and imaginary parts of permittivity were analyzed with Kramers-Kronig transformation.
- Published
- 2017
44. Effects of AO and Pacific SSTA on severe droughts in Luanhe River basin, China
- Author
-
Huihui Mao, Bernard A. Engel, Xueyang Liu, Fulong Chen, Jianzhu Li, and Yuming Lei
- Subjects
Atmospheric Science ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,Ocean current ,Drainage basin ,Geopotential height ,02 engineering and technology ,Subtropics ,01 natural sciences ,020801 environmental engineering ,La Niña ,Warm front ,Arctic oscillation ,Climatology ,Earth and Planetary Sciences (miscellaneous) ,Subtropical ridge ,Geology ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
The frequency of drought occurring in the Luanhe River basin in China has increased since 1965. The severe droughts are mainly influenced by the negative phase of Arctic Oscillation (AO) and the 12-month time-lag La Nina events. In this study, we investigate the mechanism of the severe droughts occurring in the Luanhe River basin due to the 12-month time-lag Pacific sea-surface temperature anomaly (SSTA) and AO in the Luanhe River basin for the period of 1965–2012. According to the 3-month time scale of the low-level circulations and SSTA in the Pacific Ocean, when AO is in a continuous negative phase, the geopotential height at the 500-hPa level over high-latitude regions, such as Siberia, Lake Baikal and the Ural Mountains, decreases. The Europe–Asia wave train is located southward, which results in meridional anomalous circulation prevailing over East Asia. Due to air–sea interactions, the 12-month time-lag Pacific SSTA weakens the northwestern Pacific subtropical high and blocks the warm air from the Pacific. When the negative phase of AO and La Nina happened simultaneously during 1971/1972, the first stage of 2000/2002 and 2008/2009, a severe drought occurred in the Luanhe River basin. A severe drought happened in this region during 1980/1981 and the third stage of 2000/2002 when AO was in the negative phase.
- Published
- 2017
45. Producing multiple tables for small areas with confidentiality protection
- Author
-
Laura McKenna, Jianzhu Li, and Tom Krenzke
- Subjects
Economics and Econometrics ,050208 finance ,Computer science ,05 social sciences ,Computer security ,computer.software_genre ,01 natural sciences ,Management Information Systems ,010104 statistics & probability ,Confidentiality protection ,0502 economics and business ,0101 mathematics ,Statistics, Probability and Uncertainty ,computer - Published
- 2017
46. Spatial and temporal characteristics of droughts in Luanhe River basin, China
- Author
-
Ting Zhang, Yixuan Wang, Jianzhu Li, Xu Chen, and Ping Feng
- Subjects
Atmospheric Science ,Climate pattern ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,Drainage basin ,02 engineering and technology ,Structural basin ,01 natural sciences ,020801 environmental engineering ,Trend analysis ,Climatology ,Period (geology) ,Common spatial pattern ,Environmental science ,Precipitation ,0105 earth and related environmental sciences ,Teleconnection - Abstract
The spatial and temporal characteristics of drought are investigated for Luanhe River basin, using monthly precipitation data from 26 stations covering the common period of 1958–2011. The spatial pattern of drought was assessed by applying principal component analysis (PCA) to the Standardized Precipitation Index (SPI) computed on 3- and 12-month time scales. In addition, annual SPI and seasonal SPIs (including spring SPI, summer SPI, autumn SPI, and winter SPI) were also defined and considered in this study to characterize seasonal and annual drought conditions, respectively. For all seven SPI cases, three distinctive sub-regions with different temporal evolutions of droughts are well identified, respectively, representing the southeast, middle, and northwest of the Luanhe River basin. The Mann-Kendall (MK) trend test with a trend-free pre-whitening (TFPW) procedure and Sen’s method were used to determine the temporal trends in the annual and seasonal SPI time series. The continuous wavelet transform (CWT) was employed for further detecting the periodical features of drought condition in each sub-region. Results of MK and Sen’s tests show a general tendency of intensification in summer drought over the entire basin, while a significant mitigating trend in spring drought. On the whole, an aggravating trend of inter-annual drought is discovered across the basin. Based on the CWT, the drought variability in the basin is generally dominated by 16- to 64-month cycles, and the 2- to 6-year cycles appear to be obvious when concerned with annual and seasonal droughts. Furthermore, a cross wavelet analysis was performed to examine the possible links between the drought conditions and large-scale climate patterns. The teleconnections of ENSO, NAO, PDO, and AMO show significant influences on the regional droughts principally concentrated in the 16- to 64-month period, maybe responsible for the physical causes of the cyclical behavior of drought occurrences. PDO and AMO also highlight a noteworthy correlation with drought variability on a decadal scale (around 128-month period). The findings of this study will provide valuable references for regional drought mitigation and water resource management.
- Published
- 2017
47. Phonon characteristics, crystal structure, and intrinsic properties of a Y(Mg1/2Sn1/2)O3 ceramic
- Author
-
Jing Wang, Hengyang Qiao, Zeming Qi, Chao Xing, Feng Shi, Haiqing Sun, Jianzhu Li, Jun Yang, Huiling Chen, Helei Dong, and Xunqian Yin
- Subjects
010302 applied physics ,Materials science ,Phonon ,General Chemical Engineering ,Analytical chemistry ,02 engineering and technology ,General Chemistry ,Dielectric ,Crystal structure ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular physics ,Condensed Matter::Materials Science ,symbols.namesake ,Fourier transform ,Molecular vibration ,0103 physical sciences ,symbols ,Physics::Chemical Physics ,Fourier transform infrared spectroscopy ,0210 nano-technology ,Raman spectroscopy ,Monoclinic crystal system - Abstract
Herein, a Y(Mg1/2Sn1/2)O3 (YMS) ceramic was synthesized using a conventional solid-state reaction method. Crystal structure of YMS was investigated via X-ray diffraction (XRD). Lattice vibrational modes were obtained through Raman scattering spectroscopy and Fourier transform far-infrared (FTIR) reflection spectroscopy to study its phonon characteristics. The main phase of YMS with the monoclinic P21/n symmetry has been certified via XRD. The Raman active modes fitted with the Lorentzian function can be divided into three parts: vibration related to A-site Y cations, B-site (1 : 1 ordered structure of Mg2+ : Sn4+), and O ions. The eight far-infrared spectrum modes corresponded to different atomic structures of the vibration modes. Dielectric properties (er and tan δj/ω) were deduced using the four-parameter semi-quantum model (FPSQ) and Clausius–Mossotti equation, as well as the relationship between the damping coefficient and the intrinsic loss. The imaginary and real parts of the dielectric constant were obtained via the Kramers–Kronig analysis.
- Published
- 2017
48. Effect of deficit irrigation on soil CO2 and N2O emissions and winter wheat yield
- Author
-
Hao Xiong, Jianzhu Li, and Yuxuan Zhong
- Subjects
Irrigation ,Renewable Energy, Sustainability and the Environment ,020209 energy ,Strategy and Management ,05 social sciences ,Winter wheat ,Deficit irrigation ,02 engineering and technology ,Irrigation water ,Industrial and Manufacturing Engineering ,Linear relationship ,Animal science ,Soil temperature ,Yield (wine) ,Greenhouse gas ,050501 criminology ,0202 electrical engineering, electronic engineering, information engineering ,Environmental science ,0505 law ,General Environmental Science - Abstract
Determining the features of soil CO2 and N2O emissions and the driving factors of deficit irrigation is of great significance for optimizing cropland management modes. In this study, the experimental plots were selected in a typical area of the North China Plain during the whole growth period of winter wheat. Six irrigation levels were designed to investigate the effect of deficit irrigation on CO2 and N2O emissions and wheat yield. CK represents reference irrigation (full-water irrigation), and T1-T5 represent irrigation water decreasing by 10%, 20%, 30%, 40% and 50%, respectively. The experiment showed that soil CO2 and N2O emissions decreased under the deficit irrigation treatments (T1, T2, T3, T4 and T5). Pearson correlation analysis showed that there were significant correlations between the CO2 emissions and soil temperature or water-filled pore space (WFPS) under the different irrigation treatments, and these correlations had a significant linear relationship. However, there was no discernible correlation between the N2O emissions and soil temperature or WFPS under the other irrigation treatments except the CK treatment. Compared with that of the CK treatment, the equivalent CO2 of the T1-T5 treatments decreased by 8.6%, 5.7%, 14.3%, 14.1% and 19.3%, respectively. Compared with the CK treatment, the T3-T5 treatments significantly decreased the N2O emissions (P 0.05). Moreover, some deficit irrigation treatments had negative influences on the yield of winter wheat. Through the TOPSIS method and RSR method, the effects of the irrigation levels on equivalent CO2 and wheat yield were evaluated comprehensively. The T3 treatment was shown to be the best irrigation level for the conservation of wheat yield and reduction of greenhouse gas emissions. Therefore, the corresponding irrigation water amount under the T3 treatment could be regarded as the most appropriate scheme.
- Published
- 2021
49. Drought forecasting in Luanhe River basin involving climatic indices
- Author
-
Jianzhu Li, Weinan Ren, Ping Feng, Yixuan Wang, and Ronald J. Smith
- Subjects
Atmospheric Science ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,Multivariate normal distribution ,02 engineering and technology ,Conditional probability distribution ,01 natural sciences ,Pearson product-moment correlation coefficient ,020801 environmental engineering ,symbols.namesake ,Normality test ,Climatology ,symbols ,Environmental science ,Probabilistic forecasting ,Precipitation ,Scale (map) ,Lead time ,0105 earth and related environmental sciences - Abstract
Drought is regarded as one of the most severe natural disasters globally. This is especially the case in Tianjin City, Northern China, where drought can affect economic development and people’s livelihoods. Drought forecasting, the basis of drought management, is an important mitigation strategy. In this paper, we evolve a probabilistic forecasting model, which forecasts transition probabilities from a current Standardized Precipitation Index (SPI) value to a future SPI class, based on conditional distribution of multivariate normal distribution to involve two large-scale climatic indices at the same time, and apply the forecasting model to 26 rain gauges in the Luanhe River basin in North China. The establishment of the model and the derivation of the SPI are based on the hypothesis of aggregated monthly precipitation that is normally distributed. Pearson correlation and Shapiro-Wilk normality tests are used to select appropriate SPI time scale and large-scale climatic indices. Findings indicated that longer-term aggregated monthly precipitation, in general, was more likely to be considered normally distributed and forecasting models should be applied to each gauge, respectively, rather than to the whole basin. Taking Liying Gauge as an example, we illustrate the impact of the SPI time scale and lead time on transition probabilities. Then, the controlled climatic indices of every gauge are selected by Pearson correlation test and the multivariate normality of SPI, corresponding climatic indices for current month and SPI 1, 2, and 3 months later are demonstrated using Shapiro-Wilk normality test. Subsequently, we illustrate the impact of large-scale oceanic-atmospheric circulation patterns on transition probabilities. Finally, we use a score method to evaluate and compare the performance of the three forecasting models and compare them with two traditional models which forecast transition probabilities from a current to a future SPI class. The results show that the three proposed models outperform the two traditional models and involving large-scale climatic indices can improve the forecasting accuracy.
- Published
- 2016
50. Drought class transition analysis through different models: a case study in North China
- Author
-
Ting Zhang, Yixuan Wang, R. Hu, Jianzhu Li, and Ping Feng
- Subjects
010504 meteorology & atmospheric sciences ,Markov chain ,Scale (ratio) ,0208 environmental biotechnology ,Chaotic ,Volterra series ,02 engineering and technology ,01 natural sciences ,020801 environmental engineering ,Adaptive filter ,Water resources ,Climatology ,Log-linear model ,Surface runoff ,0105 earth and related environmental sciences ,Water Science and Technology ,Mathematics - Abstract
The standardized precipitation index (SPI) and standardized runoff index (SRI) are computed for several gauge stations in Panjiakou Reservoir catchment of Luanhe Basin, a drought prone region of North China. Based on the SPI and SRI time series, two different models, a weighted Markov chain model and a Volterra adaptive filter model for chaotic time series, were established to predict drought classes and achieve both short- and long-term drought forecasting. These approaches were compared with a three-dimensional (3D) loglinear model, reported in our previous work. It was observed that all the three models have pros and cons when applied to drought prediction in Panjiakou Reservoir catchment. The 3D loglinear model is able to forecast drought class within 1 month. However, its predicting accuracy declines with the increase of prediction time scale, and this confines its application. The weighted Markov chain model is a useful tool for drought early warning. Its precision, which is significantly related to the stable condition of drought classes, is highest for Non-drought, followed by Moderate and Severe/Extreme drought, and lowest for Near-normal. The Volterra adaptive filter model for chaotic time series combined the phase space reconstruction technique, Volterra series expansion technique and adaptive filter optimization technique, and was for the first time used in a drought class transition study. This model is effective and highly precise in long-term drought prediction (for example, 12 months). It is able to provide reliable information for the medium- and long-term decisions and plans for water resources systems.
- Published
- 2016
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