Due to the considerable uncertainties inherent in the datasets describing the spatiotemporal distributions of precipitation in the drylands of China,this study presents a new merged monthly precipitation product with ...Due to the considerable uncertainties inherent in the datasets describing the spatiotemporal distributions of precipitation in the drylands of China,this study presents a new merged monthly precipitation product with a spatial resolution of approximately 0.2°×0.2°during 1980–2019.The newly developed precipitation product was validated at different temporal scales(e.g.,monthly,seasonally,and annually).The results show that the new product consistently aligns with the spatiotemporal distributions reported by the Chinese Meteorological Administration Land Data Assimilation System(CLDAS)product and Multi-Source Weighted Ensemble Precipitation(MSWEP).The merged product exhibits exceptional quality in describing the drylands of China,with a bias of–2.19 mm month^(–1)relative to MSWEP.In addition,the annual trend of the merged product(0.09 mm month^(–1)yr^(−1))also closely aligns with that of the MSWEP(0.11 mm month^(–1)yr^(−1))during 1980–2019.The increasing trend indicates that the water cycle and wetting process intensified in the drylands of China during this period.In particular,there was an increase in wetting during the period from 2001–2019.Generally,the merged product exhibits potential value for improving our understanding of the climate and water cycle in the drylands of China.展开更多
Pharmacophore is a commonly used method for molecular simulation, including ligand-based pharmacophore (LBP) and structure-based pharmacophore (SBP). LBP can be utilized to identify active compounds usual with low...Pharmacophore is a commonly used method for molecular simulation, including ligand-based pharmacophore (LBP) and structure-based pharmacophore (SBP). LBP can be utilized to identify active compounds usual with lower accuracy, and SBP is able to use for distin- guishing active compounds from inactive compounds with frequently higher missing rates. Merged pharmacophore (MP) is presented to integrate advantages and avoid shortcomings of LBP and SBP. In this work, LBP and SBP models were constructed for the study of per- oxisome proliferator receptor-alpha (PPARα) agonists. According to the comparison of the two types of pharmacophore models, mainly and secondarily pharmacological features were identified. The weight and tolerance values of these pharmacological features were adjusted to construct MP models by single-factor explorations and orthogonal experimental design based on SBP model. Then, the reliability and screening efficiency of the best MP model were validated by three databases. The best MP model was utilized to compute PPARα activity of compounds from traditional Chinese medicine. The screening efficiency of MP model outperformed individual LBP or SBP model for PPARα agonists, and was similar to combinatorial screening of LBP and SBP. However, MP model might have an advantage over the combination of LBP and SBP in evaluating the activity of compounds and avoiding the inconsistent prediction of LBP and SBP, which would be beneficial to guide drug design and optimization.展开更多
Wave energy resources are abundant in both offshore and nearshore areas of the China's seas. A reliable assessment of the wave energy resources must be performed before they can be exploited. First, for a water depth...Wave energy resources are abundant in both offshore and nearshore areas of the China's seas. A reliable assessment of the wave energy resources must be performed before they can be exploited. First, for a water depth in offshore waters of China, a parameterized wave power density model that considers the effects of the water depth is introduced to improve the calculating accuracy of the wave power density. Second, wave heights and wind speeds on the surface of the China's seas are retrieved from an AVISO multi-satellite altim-eter data set for the period from 2009 to 2013. Three mean wave period inversion models are developed and used to calculate the wave energy period. Third, a practical application value for developing the wave energy is analyzed based on buoy data. Finally, the wave power density is then calculated using the wave field data. Using the distribution of wave power density, the energy level frequency, the time variability indexes, the to-tal wave energy and the distribution of total wave energy density according to a wave state, the offshore wave energy in the China's seas is assessed. The results show that the areas of abundant and stable wave energy are primarily located in the north-central part of the South China Sea, the Luzon Strait, southeast of Taiwan in the China's seas; the wave power density values in these areas are approximately 14.0–18.5 kW/m. The wave energy in the China’s seas presents obvious seasonal variations and optimal seasons for a wave energy utilization are in winter and autumn. Except for very coastal waters, in other sea areas in the China's seas, the energy is primarily from the wave state with 0.5 m≤Hs≤4 m, 4 s≤Te≤10 s whereHs is a significant wave height andTe is an energy period; within this wave state, the wave energy accounts for 80% above of the total wave energy. This characteristic is advantageous to designing wave energy convertors (WECs). The practical application value of the wave energy is higher which can be as an effective supplement for an energy con-sumption in some areas. The above results are consistent with the wave model which indicates fully that this new microwave remote sensing method altimeter is effective and feasible for the wave energy assessment.展开更多
Understanding the ocean's role in the global carbon cycle and its response to environmental change requires a high spatio-temporal resolution of observation.Merging ocean color data from multiple sources is an effect...Understanding the ocean's role in the global carbon cycle and its response to environmental change requires a high spatio-temporal resolution of observation.Merging ocean color data from multiple sources is an effective way to alleviate the limitation of individual ocean color sensors(e.g.,swath width and gaps,cloudy or rainy weather,and sun glint) and to improve the temporal and spatial coverage.Since the missions of Sea-Viewing Wide Field-of-View Sensor(Sea Wi FS) and Medium-spectral Resolution Imaging Spectrometer(MERIS) ended on December 11,2010 and May 9,2012,respectively,the number of available ocean color sensors has declined,reducing the benefits of the merged ocean color data with respect to the spatial and temporal coverage.In present work,Medium Resolution Spectral Imager(MERSI)/FY-3 of China is added in merged processing and a new dataset of global ocean chlorophyll a(Chl a) concentration(2000–2015) is generated from the remote sensing reflectance(Rrs(λ)) observations of MERIS,Moderate-resolution imaging spectra-radiometer(MODIS)-AQUA,Visible infrared Imaging Radiometer(VIIRS) and MERSI.These data resources are first merged into unified remote sensing reflectance data,and then Chl a concentration data are inversed using the combined Chl a algorithm of color index-based algorithm(CIA) and OC3.The merged data products show major improvements in spatial and temporal coverage from the addition of MERSI.The average daily coverage of merged products is approximately 24% of the global ocean and increases by approximately 9% when MERSI data are added in the merging process.Sampling frequency(temporal coverage) is greatly improved by combining MERSI data,with the median sampling frequency increasing from 15.6%(57 d/a) to 29.9%(109 d/a).The merged Chl a products herein were validated by in situ measurements and comparing them with the merged products using the same approach except for omitting MERSI and Glob Colour and MEa SUREs merged data.Correlation and relative error between the new merged Chl a products and in situ observation are stable relative to the results of the merged products without the addition of MERSI.Time series of the Chl a concentration anomalies are similar to the merged products without adding MERSI and single sensors.The new merged products agree within approximately 10% of the merged Chl a product from Glob Colour and MEa SUREs.展开更多
A novel 4 H-Si C merged P–I–N Schottky(MPS)with floating back-to-back diode(FBD),named FBD-MPS,is proposed and investigated by the Sentaurus technology computer-aided design(TCAD)and analytical model.The FBD feature...A novel 4 H-Si C merged P–I–N Schottky(MPS)with floating back-to-back diode(FBD),named FBD-MPS,is proposed and investigated by the Sentaurus technology computer-aided design(TCAD)and analytical model.The FBD features a trench oxide and floating P-shield,which is inserted between the P+/N-(PN)junction and Schottky junction to eliminate the shorted anode effect.The FBD is formed by the N-drift/P-shield/N-drift and it separates the PN and Schottky active region independently.The FBD reduces not only the Vturn to suppress the snapback effect but also the Von at bipolar operation.The results show that the snapback can be completely eliminated,and the maximum electric field(Emax)is shifted from the Schottky junction to the FBD in the breakdown state.展开更多
In this paper, a mixed terminal structure for the 4H-SiC merged PiN/Schottky diode (MPS) is investigated, which is a combination of a field plate, a junction termination extension and floating limiting rings. Optimi...In this paper, a mixed terminal structure for the 4H-SiC merged PiN/Schottky diode (MPS) is investigated, which is a combination of a field plate, a junction termination extension and floating limiting rings. Optimization is performed on the terminal structure by using the ISE-TCAD. Further analysis shows that this structure can greatly reduce the sensitivity of the breakdown voltage to the doping concentration and can effectively suppress the effect of the interface charge compared with the structure of the junction termination extension. At the same time, the 4H-SiC MPS with this termination structure can reach a high and stable breakdown voltage.展开更多
Using 20 years (1993-2012) of merged data recorded by contemporary multi-altimeter missions, a variety of sea-level variability modes are recovered in the South China Sea employing three- dimensional harmonic extrac...Using 20 years (1993-2012) of merged data recorded by contemporary multi-altimeter missions, a variety of sea-level variability modes are recovered in the South China Sea employing three- dimensional harmonic extraction. In terms of the long-term variation, the South China Sea is estimated to have a rising sea-level linear trend of 5.39 mm/a over these 20 years. Among the modes extracted, the seven most statistically significant periodic or quasi-periodic modes are identified as principal modes. The geographical distributions of the magnitudes and phases of the modes are displayed. In terms of intra- annual and annual regimes, two principal modes with strict semiannual and annual periods are found, with the annual variability having the largest amplitudes among the seven modes. For interannual and decadal regimes, five principal modes at approximately 18, 21, 23, 28, and 112 months are found with the most mode- active region being to the east of Vietnam. For the phase distributions, a series of amphidromes are observed as twins, termed "amphidrome twins", comprising rotating dipole systems. The stability of periodic modes is investigated employing joint spatiotemporal analysis of latitude/longitude sections. Results show that all periodic modes are robust, revealing the richness and complexity of sea-level modes in the South China Sea.展开更多
This paper investigates the behaviours of 4H--SiC merged PiN Schottky (MPS) rectifiers with junction termination extension (JTE) by extensive numerical simulations. The simulated results show that the present mode...This paper investigates the behaviours of 4H--SiC merged PiN Schottky (MPS) rectifiers with junction termination extension (JTE) by extensive numerical simulations. The simulated results show that the present model matches the experimental data very well. The influences of the JTE design parameters such as the doping concentration and length of the JTE on the breakdown characteristics are discussed in detail. Then the temperature sensitivity of the forward behaviour is studied in terms of the different designs of 4H--SiC MPS with JTE, which provides a particularly useful guideline for the optimal design of MPS rectifiers with JTE.展开更多
Sea surface salinity(SSS)is an essential variable of ocean dynamics and climate research.The Soil Moisture and Ocean Salinity(SMOS),Aquarius,and Soil Moisture Active Passive(SMAP)satellite missions all provide SSS mea...Sea surface salinity(SSS)is an essential variable of ocean dynamics and climate research.The Soil Moisture and Ocean Salinity(SMOS),Aquarius,and Soil Moisture Active Passive(SMAP)satellite missions all provide SSS measurements.The European Space Agency(ESA)Climate Change Initiative Sea Surface Salinity(CCI-SSS)project merged these three satellite SSS data to produce CCI L4SSS products.We validated the accuracy of the four satellite products(CCI,SMOS,Aquarius,and SMAP)using in-situ gridded data and Argo floats in the South China Sea(SCS).Compared with in-situ gridded data,it shows that the CCI achieved the best performance(RMSD:0.365)on monthly time scales.The RMSD of SMOS,Aquarius,and SMAP(SMOS:0.389;Aquarius:0.409;SMAP:0.391)are close,and the SMOS takes a slight advantage in contrast with Aquarius and SMAP.Large discrepancies can be found near the coastline and in the shelf seas.Meanwhile,CCI with lower RMSD(0.295)perform better than single satellite data(SMOS:0.517;SMAP:0.297)on weekly time scales compared with Argo floats.Overall,the merged CCI have the smallest RMSD among the four satellite products in the SCS on both weekly time scales and monthly time scales,which illustrates the improved accuracy of merged CCI compared with the individual satellite data.展开更多
A new structure of 4H-silicon carbide (SIC) merged PiN-Schottky (MPS) diodes with offset field-plate (FP) as edge termination is developed. To understand the influences of 4H-SiC MPS diodes with offset FP on the...A new structure of 4H-silicon carbide (SIC) merged PiN-Schottky (MPS) diodes with offset field-plate (FP) as edge termination is developed. To understand the influences of 4H-SiC MPS diodes with offset FP on the characteristics, simulations have been done by using ISE TCAD. Related factors of offset FP have been studied as well to optimise the reverse characteristics of 4H SiC MPS diodes. The simulation results show that the device using offset FP can create a higher blocking voltage under reverse bias as compared with that using field guard rings. Besides, the offset FP does not cause any extra steps in the manufacture of MPS diodes.展开更多
A new analytical model for reverse characteristics of 4H-SiC merged PN Sehottky diodes (MPS or 3BS) is developed. To accurately calculate the reverse characteristics of the 4H SiC MPS diode, the relationship between...A new analytical model for reverse characteristics of 4H-SiC merged PN Sehottky diodes (MPS or 3BS) is developed. To accurately calculate the reverse characteristics of the 4H SiC MPS diode, the relationship between the electric field at the Schottky contact and the reverse bias is analytically established by solving the cylindrical Poisson equation after the channel has pinched off. The reverse current density calculated from the Wentzel-Kramers-Brillouin (WKB) theory is verified by comparing it with the experimental result, showing that they are in good agreement with each other. Moreover, the effects of P-region spacing (S) and P-junction depth (Xj) on the characteristics of 4H-SiC MPS are analysed, and are particularly useful for optimizing the design of the high voltage MPS diodes.展开更多
In the modern society,there is a strong demand for semiconductor chips,and the 4H polytype silicon carbide(4H-SiC)power device is a promising candidate for the next generation semiconductor chip,which can be used in v...In the modern society,there is a strong demand for semiconductor chips,and the 4H polytype silicon carbide(4H-SiC)power device is a promising candidate for the next generation semiconductor chip,which can be used in various power electronic systems.In order to improve the performance of the 4H-SiC power device,a novel ultrahigh-voltage(UHV)4H-SiC merged p-type/intrinsic/n-type(PiN)Schottky(MPS)diode with three-dimensional(3D)p-type buried layers(PBL)(3D-PBL MPS)is proposed and investigated by numerical simulation.The static forward conduction characteristics of the 3D-PBL MPS are similar to those of the conventional 4H-SiC MPS diode without the PBL(PBL-free MPS).However,when the 3D-PBL MPS is in the reverse blocking state,the 3D PBL can transfer the peak electric field(E_(peak))into a deeper position in the body of the epitaxial layer,and enhance the ability of the device to shield the high electric field at the Schottky contact interface(E_(S)),so that the reverse leakage current of the 3D-PBL MPS at 10 kV is only 0.002%of that of the PBL-free MPS.Meanwhile,the novel 3D-PBL MPS has overcome the disadvantage in the 4H-SiC MPS diode with the two-dimensional PBL(2D-PBL MPS),and the forward conduction characteristic of the 3D-PBL MPS will not get degenerated after the device converts from the reverse blocking state to the forward conduction state because of the special depletion layer variation mechanism depending on the 3D PBL.All the simulation results show that the novel UHV 3D-PBL MPS has excellent device performance.展开更多
A method to improve the surge current capability of silicon carbide(SiC)merged PiN Schottky(MPS)diodes is presented and investigated via three-dimensional electro-thermal simulations.When compared with a conventional ...A method to improve the surge current capability of silicon carbide(SiC)merged PiN Schottky(MPS)diodes is presented and investigated via three-dimensional electro-thermal simulations.When compared with a conventional MPS diode,the proposed structure has a more uniform current distribution during bipolar conduction due to the help of the continuous P+surface,which can avoid the formation of local hotspots during the surge process.The Silvaco simulation results show that the proposed structure has a 20.29%higher surge capability and a 15.06%higher surge energy compared with a conventional MPS diode.The bipolar on-state voltage of the proposed structure is 4.69 V,which is 56.29%lower than that of a conventional MPS diode,enabling the device to enter the bipolar mode earlier during the surge process.Furthermore,the proposed structure can suppress the occurrence of‘snapback'phenomena when switching from the unipolar to the bipolar operation mode.In addition,an analysis of the surge process of MPS diodes is carried out in detail.展开更多
Aiming at the problem of merging heterogeneous semantic taxonomy emerged in Web information integration, a method of building Web classification ontology (WCO) has been proposed. A WCO that is logically consistent w...Aiming at the problem of merging heterogeneous semantic taxonomy emerged in Web information integration, a method of building Web classification ontology (WCO) has been proposed. A WCO that is logically consistent with the suggested upper merged ontology (SUMO) is defined, together with axioms needed to classify Web pages. WCO can be used as a foundation of merging heterogeneous semantic taxonomy, and could be used to support Web information integration and classification based Web information retrieval.展开更多
Employing the merged quasi-geoid, we analyses the causes of systematic errors in modelling of quasigeoid of neighbouring areas in the paper, and the efficient method is introduced to improve the accuracy of quasi-geoi...Employing the merged quasi-geoid, we analyses the causes of systematic errors in modelling of quasigeoid of neighbouring areas in the paper, and the efficient method is introduced to improve the accuracy of quasi-geoid. First, the systematic error is weakened with the moving window method applied to established quasi-geoids in two adjacent regions, and the accuracy of the merged quasi-geoid in the stitching region is checked using the measured GPS benchmark data; Second, the whole quasi-geoid is recomputed with data obtained from two adjacent regions if the accuracy of the quasi-geoid obtained from the first step in the stitching region is low; Finally, the quasi-geoids in two adjacent regions are recomputed respectively using GPS benchmark data of own region and adjacent region with the same solution if the accuracy of whole quasi-geoid obtained from the second step also is low. Actual data sets from Sichuan Province and Chongqing City are employed to test the moving window method. It is shown that the quasi-geoid models with high resolution and accuracy were obtained.展开更多
Apreludial step of the current drive for structural adjustment in the CAS system, the establishment of Xinjiang Institute of Ecology & Geography was announced on July 7, 1998. The new institute is to incorporate t...Apreludial step of the current drive for structural adjustment in the CAS system, the establishment of Xinjiang Institute of Ecology & Geography was announced on July 7, 1998. The new institute is to incorporate the research resources of two former CAS institutes in the region in a bid to concentrate scattered R&D expertise and promote the interdependence of different disciplines in the implementation of national program展开更多
Martens proposed a highly efficient and simply formed DFT algorithm——RCFA,whose efficien-cy is comparable with that of WFTA or that of PFA,and whose structure is similar to that of FFT.Theauthors have proved that,in...Martens proposed a highly efficient and simply formed DFT algorithm——RCFA,whose efficien-cy is comparable with that of WFTA or that of PFA,and whose structure is similar to that of FFT.Theauthors have proved that,in the case of radix 2,the RCFA is exactly equivalent to the twiddle factor mergedfrequency-decimal FFT algorithm.The twiddle factor merged time-decimal FFT algorithm is providedin this paper.Thus,in any case,the FFT algorithm used currently can be replaced by the more efficientalgorithm——the twiddle factor merged FFT algorithm,with exactly the same external property and thesimilar internal structure.Also in this paper,the software for implementing the twiddle factor merged FFTalgorithm(TMFFT)is provided.展开更多
The purpose of this paper is to evaluate the result of merge three companies.The researcher has examined the merge case through the collected information from three senior managers.The financial losses and mismanageme...The purpose of this paper is to evaluate the result of merge three companies.The researcher has examined the merge case through the collected information from three senior managers.The financial losses and mismanagement(after the merge)are the critical problems of the merge.The best solution is proper planning.A business plan can help companies to achieve their priorities.The operations deliver high performance by managerial processes that performance in the long-term.Moreover,the company shall care of employees through defining companies’capabilities.The professional management will have a direct positive effect on the company’s performance while unprofessional management will have a negative impact on company performance—also,the unprofessional merge negative effect in leading the company to success.展开更多
目的:对比三维多回波恢复梯度回波(3D MERGE)、三维可变反转角快速自旋回波(3D SPACE STIR)序列在腰椎间盘突出症(LDH)检查中的应用效果。方法:选择2020年1月~2022年11月收治的135例LDH患者,回顾性分析患者临床和磁共振成像(MRI)资料,...目的:对比三维多回波恢复梯度回波(3D MERGE)、三维可变反转角快速自旋回波(3D SPACE STIR)序列在腰椎间盘突出症(LDH)检查中的应用效果。方法:选择2020年1月~2022年11月收治的135例LDH患者,回顾性分析患者临床和磁共振成像(MRI)资料,所有患者均接受常规MRI扫描及3D MERGE、3D SPACE STIR序列扫描,对比3D MERGE、3D SPACE STIR序列测量神经根直径的一致性,评价两种序列的图像质量参数[信噪比(SNR)、对比噪声比(CNR)]、图像清晰度评分。结果:3D MERGE和3D SPACE STIR序列测量的L3~S1神经根直径比较差异无统计学意义(P>0.05),且两组序列测量的L3、L4、L5和S1直径均显示出较高相关性(r=0.957,0.986,0.975,0.972,P<0.05);3D MERGE序列的SNR及CNR均高于3D SPACE STIR序列,神经根显示分级、图像清晰度评分优于3D SPACE STIR序列,差异有统计学意义(P<0.05)。结论:3D MERGE、3D SPACE STIR序列在LDH神经根直径测量中具有极高一致性,3D MERGE序列较3D SPACE STIR序列能够更清晰显示神经跟的解剖形态,图像质量更好。展开更多
在循证医学时代下,依托规范的技术方法和标准化的操作规程发掘中医药独特优势,是实现中医药现代化、国际化发展并惠泽人类的必由之路。中医理论、人用经验和研究证据三结合证据体系的提出标志着中医药特色评价体系思维方法取得了重要进...在循证医学时代下,依托规范的技术方法和标准化的操作规程发掘中医药独特优势,是实现中医药现代化、国际化发展并惠泽人类的必由之路。中医理论、人用经验和研究证据三结合证据体系的提出标志着中医药特色评价体系思维方法取得了重要进步,经过恰当方法整合后的多元证据体是中医药临床指南推荐意见和循证卫生决策的有力支撑。本文基于当前国际证据合成与分级方法学前沿进展,初步提出中医药多元证据整合的方法学框架——MERGE(Merge Evidence-based Research and artificial intelliGence to support smart dEcision)框架,以期为中医药循证医学方法学体系的完善和发展提供借鉴和参考。展开更多
基金supported by the National Natural Science Foundation of China the National Natural Science Foundation of China(Grant No.41991231)the Fundamental Research Funds for the Central Universities(lzujbky-2022-kb11).
文摘Due to the considerable uncertainties inherent in the datasets describing the spatiotemporal distributions of precipitation in the drylands of China,this study presents a new merged monthly precipitation product with a spatial resolution of approximately 0.2°×0.2°during 1980–2019.The newly developed precipitation product was validated at different temporal scales(e.g.,monthly,seasonally,and annually).The results show that the new product consistently aligns with the spatiotemporal distributions reported by the Chinese Meteorological Administration Land Data Assimilation System(CLDAS)product and Multi-Source Weighted Ensemble Precipitation(MSWEP).The merged product exhibits exceptional quality in describing the drylands of China,with a bias of–2.19 mm month^(–1)relative to MSWEP.In addition,the annual trend of the merged product(0.09 mm month^(–1)yr^(−1))also closely aligns with that of the MSWEP(0.11 mm month^(–1)yr^(−1))during 1980–2019.The increasing trend indicates that the water cycle and wetting process intensified in the drylands of China during this period.In particular,there was an increase in wetting during the period from 2001–2019.Generally,the merged product exhibits potential value for improving our understanding of the climate and water cycle in the drylands of China.
文摘Pharmacophore is a commonly used method for molecular simulation, including ligand-based pharmacophore (LBP) and structure-based pharmacophore (SBP). LBP can be utilized to identify active compounds usual with lower accuracy, and SBP is able to use for distin- guishing active compounds from inactive compounds with frequently higher missing rates. Merged pharmacophore (MP) is presented to integrate advantages and avoid shortcomings of LBP and SBP. In this work, LBP and SBP models were constructed for the study of per- oxisome proliferator receptor-alpha (PPARα) agonists. According to the comparison of the two types of pharmacophore models, mainly and secondarily pharmacological features were identified. The weight and tolerance values of these pharmacological features were adjusted to construct MP models by single-factor explorations and orthogonal experimental design based on SBP model. Then, the reliability and screening efficiency of the best MP model were validated by three databases. The best MP model was utilized to compute PPARα activity of compounds from traditional Chinese medicine. The screening efficiency of MP model outperformed individual LBP or SBP model for PPARα agonists, and was similar to combinatorial screening of LBP and SBP. However, MP model might have an advantage over the combination of LBP and SBP in evaluating the activity of compounds and avoiding the inconsistent prediction of LBP and SBP, which would be beneficial to guide drug design and optimization.
基金The Ocean Renewable Energy Special Fund Project of the State Oceanic Administration of China under contract No.GHME2011ZC07the Dragon Ⅲ Project of the European Space Agency and Ministry of Science and Technology of China under contract No.10412
文摘Wave energy resources are abundant in both offshore and nearshore areas of the China's seas. A reliable assessment of the wave energy resources must be performed before they can be exploited. First, for a water depth in offshore waters of China, a parameterized wave power density model that considers the effects of the water depth is introduced to improve the calculating accuracy of the wave power density. Second, wave heights and wind speeds on the surface of the China's seas are retrieved from an AVISO multi-satellite altim-eter data set for the period from 2009 to 2013. Three mean wave period inversion models are developed and used to calculate the wave energy period. Third, a practical application value for developing the wave energy is analyzed based on buoy data. Finally, the wave power density is then calculated using the wave field data. Using the distribution of wave power density, the energy level frequency, the time variability indexes, the to-tal wave energy and the distribution of total wave energy density according to a wave state, the offshore wave energy in the China's seas is assessed. The results show that the areas of abundant and stable wave energy are primarily located in the north-central part of the South China Sea, the Luzon Strait, southeast of Taiwan in the China's seas; the wave power density values in these areas are approximately 14.0–18.5 kW/m. The wave energy in the China’s seas presents obvious seasonal variations and optimal seasons for a wave energy utilization are in winter and autumn. Except for very coastal waters, in other sea areas in the China's seas, the energy is primarily from the wave state with 0.5 m≤Hs≤4 m, 4 s≤Te≤10 s whereHs is a significant wave height andTe is an energy period; within this wave state, the wave energy accounts for 80% above of the total wave energy. This characteristic is advantageous to designing wave energy convertors (WECs). The practical application value of the wave energy is higher which can be as an effective supplement for an energy con-sumption in some areas. The above results are consistent with the wave model which indicates fully that this new microwave remote sensing method altimeter is effective and feasible for the wave energy assessment.
基金The National Key R&D Program of China under contract No.2016YFA0600102the National Natural Science Foundation of China under contract Nos 41506203,41476159,41506204,41606197,41471303 and 41706209the Cooperation Project of FIO and KOIST under contract No.PI-2017-03
文摘Understanding the ocean's role in the global carbon cycle and its response to environmental change requires a high spatio-temporal resolution of observation.Merging ocean color data from multiple sources is an effective way to alleviate the limitation of individual ocean color sensors(e.g.,swath width and gaps,cloudy or rainy weather,and sun glint) and to improve the temporal and spatial coverage.Since the missions of Sea-Viewing Wide Field-of-View Sensor(Sea Wi FS) and Medium-spectral Resolution Imaging Spectrometer(MERIS) ended on December 11,2010 and May 9,2012,respectively,the number of available ocean color sensors has declined,reducing the benefits of the merged ocean color data with respect to the spatial and temporal coverage.In present work,Medium Resolution Spectral Imager(MERSI)/FY-3 of China is added in merged processing and a new dataset of global ocean chlorophyll a(Chl a) concentration(2000–2015) is generated from the remote sensing reflectance(Rrs(λ)) observations of MERIS,Moderate-resolution imaging spectra-radiometer(MODIS)-AQUA,Visible infrared Imaging Radiometer(VIIRS) and MERSI.These data resources are first merged into unified remote sensing reflectance data,and then Chl a concentration data are inversed using the combined Chl a algorithm of color index-based algorithm(CIA) and OC3.The merged data products show major improvements in spatial and temporal coverage from the addition of MERSI.The average daily coverage of merged products is approximately 24% of the global ocean and increases by approximately 9% when MERSI data are added in the merging process.Sampling frequency(temporal coverage) is greatly improved by combining MERSI data,with the median sampling frequency increasing from 15.6%(57 d/a) to 29.9%(109 d/a).The merged Chl a products herein were validated by in situ measurements and comparing them with the merged products using the same approach except for omitting MERSI and Glob Colour and MEa SUREs merged data.Correlation and relative error between the new merged Chl a products and in situ observation are stable relative to the results of the merged products without the addition of MERSI.Time series of the Chl a concentration anomalies are similar to the merged products without adding MERSI and single sensors.The new merged products agree within approximately 10% of the merged Chl a product from Glob Colour and MEa SUREs.
文摘A novel 4 H-Si C merged P–I–N Schottky(MPS)with floating back-to-back diode(FBD),named FBD-MPS,is proposed and investigated by the Sentaurus technology computer-aided design(TCAD)and analytical model.The FBD features a trench oxide and floating P-shield,which is inserted between the P+/N-(PN)junction and Schottky junction to eliminate the shorted anode effect.The FBD is formed by the N-drift/P-shield/N-drift and it separates the PN and Schottky active region independently.The FBD reduces not only the Vturn to suppress the snapback effect but also the Von at bipolar operation.The results show that the snapback can be completely eliminated,and the maximum electric field(Emax)is shifted from the Schottky junction to the FBD in the breakdown state.
基金supported by the National Natural Science Foundation of China(Grant No.61006060)the Shaanxi Provincial 13115 Innovation Engineering,China(Grant No.2008ZDKG-30)
文摘In this paper, a mixed terminal structure for the 4H-SiC merged PiN/Schottky diode (MPS) is investigated, which is a combination of a field plate, a junction termination extension and floating limiting rings. Optimization is performed on the terminal structure by using the ISE-TCAD. Further analysis shows that this structure can greatly reduce the sensitivity of the breakdown voltage to the doping concentration and can effectively suppress the effect of the interface charge compared with the structure of the junction termination extension. At the same time, the 4H-SiC MPS with this termination structure can reach a high and stable breakdown voltage.
基金Supported by the National Natural Science Foundation of China(Nos.41331172,U1406404)the National High Technology Research and Development Program of China(863 Program)(No.2013AA09A505)
文摘Using 20 years (1993-2012) of merged data recorded by contemporary multi-altimeter missions, a variety of sea-level variability modes are recovered in the South China Sea employing three- dimensional harmonic extraction. In terms of the long-term variation, the South China Sea is estimated to have a rising sea-level linear trend of 5.39 mm/a over these 20 years. Among the modes extracted, the seven most statistically significant periodic or quasi-periodic modes are identified as principal modes. The geographical distributions of the magnitudes and phases of the modes are displayed. In terms of intra- annual and annual regimes, two principal modes with strict semiannual and annual periods are found, with the annual variability having the largest amplitudes among the seven modes. For interannual and decadal regimes, five principal modes at approximately 18, 21, 23, 28, and 112 months are found with the most mode- active region being to the east of Vietnam. For the phase distributions, a series of amphidromes are observed as twins, termed "amphidrome twins", comprising rotating dipole systems. The stability of periodic modes is investigated employing joint spatiotemporal analysis of latitude/longitude sections. Results show that all periodic modes are robust, revealing the richness and complexity of sea-level modes in the South China Sea.
基金Project supported by Shaanxi 13115 Innovation Engineering Foundation (Grant No. 2008ZDKG-30)Pre-research Project(Grant No. 51308040302)
文摘This paper investigates the behaviours of 4H--SiC merged PiN Schottky (MPS) rectifiers with junction termination extension (JTE) by extensive numerical simulations. The simulated results show that the present model matches the experimental data very well. The influences of the JTE design parameters such as the doping concentration and length of the JTE on the breakdown characteristics are discussed in detail. Then the temperature sensitivity of the forward behaviour is studied in terms of the different designs of 4H--SiC MPS with JTE, which provides a particularly useful guideline for the optimal design of MPS rectifiers with JTE.
基金Supported by the National Natural Science Foundation of China(No.42075149)。
文摘Sea surface salinity(SSS)is an essential variable of ocean dynamics and climate research.The Soil Moisture and Ocean Salinity(SMOS),Aquarius,and Soil Moisture Active Passive(SMAP)satellite missions all provide SSS measurements.The European Space Agency(ESA)Climate Change Initiative Sea Surface Salinity(CCI-SSS)project merged these three satellite SSS data to produce CCI L4SSS products.We validated the accuracy of the four satellite products(CCI,SMOS,Aquarius,and SMAP)using in-situ gridded data and Argo floats in the South China Sea(SCS).Compared with in-situ gridded data,it shows that the CCI achieved the best performance(RMSD:0.365)on monthly time scales.The RMSD of SMOS,Aquarius,and SMAP(SMOS:0.389;Aquarius:0.409;SMAP:0.391)are close,and the SMOS takes a slight advantage in contrast with Aquarius and SMAP.Large discrepancies can be found near the coastline and in the shelf seas.Meanwhile,CCI with lower RMSD(0.295)perform better than single satellite data(SMOS:0.517;SMAP:0.297)on weekly time scales compared with Argo floats.Overall,the merged CCI have the smallest RMSD among the four satellite products in the SCS on both weekly time scales and monthly time scales,which illustrates the improved accuracy of merged CCI compared with the individual satellite data.
基金Project supported by Applied Materials Innovation Fund (Grant No. XA-AM-200702)the 13115 Innovation Engineering of Shaanxi Province,China (Grant No. 2008ZDKG-30)
文摘A new structure of 4H-silicon carbide (SIC) merged PiN-Schottky (MPS) diodes with offset field-plate (FP) as edge termination is developed. To understand the influences of 4H-SiC MPS diodes with offset FP on the characteristics, simulations have been done by using ISE TCAD. Related factors of offset FP have been studied as well to optimise the reverse characteristics of 4H SiC MPS diodes. The simulation results show that the device using offset FP can create a higher blocking voltage under reverse bias as compared with that using field guard rings. Besides, the offset FP does not cause any extra steps in the manufacture of MPS diodes.
基金Project supported by the Xi’an Applied Materials Innovation Fund (Grant No XA-AM-200702)
文摘A new analytical model for reverse characteristics of 4H-SiC merged PN Sehottky diodes (MPS or 3BS) is developed. To accurately calculate the reverse characteristics of the 4H SiC MPS diode, the relationship between the electric field at the Schottky contact and the reverse bias is analytically established by solving the cylindrical Poisson equation after the channel has pinched off. The reverse current density calculated from the Wentzel-Kramers-Brillouin (WKB) theory is verified by comparing it with the experimental result, showing that they are in good agreement with each other. Moreover, the effects of P-region spacing (S) and P-junction depth (Xj) on the characteristics of 4H-SiC MPS are analysed, and are particularly useful for optimizing the design of the high voltage MPS diodes.
基金Project(F2020210016) supported by the Natural Science Foundation of Hebei,ChinaProject(620004153) supported by the National Natural Science Foundation of China。
文摘In the modern society,there is a strong demand for semiconductor chips,and the 4H polytype silicon carbide(4H-SiC)power device is a promising candidate for the next generation semiconductor chip,which can be used in various power electronic systems.In order to improve the performance of the 4H-SiC power device,a novel ultrahigh-voltage(UHV)4H-SiC merged p-type/intrinsic/n-type(PiN)Schottky(MPS)diode with three-dimensional(3D)p-type buried layers(PBL)(3D-PBL MPS)is proposed and investigated by numerical simulation.The static forward conduction characteristics of the 3D-PBL MPS are similar to those of the conventional 4H-SiC MPS diode without the PBL(PBL-free MPS).However,when the 3D-PBL MPS is in the reverse blocking state,the 3D PBL can transfer the peak electric field(E_(peak))into a deeper position in the body of the epitaxial layer,and enhance the ability of the device to shield the high electric field at the Schottky contact interface(E_(S)),so that the reverse leakage current of the 3D-PBL MPS at 10 kV is only 0.002%of that of the PBL-free MPS.Meanwhile,the novel 3D-PBL MPS has overcome the disadvantage in the 4H-SiC MPS diode with the two-dimensional PBL(2D-PBL MPS),and the forward conduction characteristic of the 3D-PBL MPS will not get degenerated after the device converts from the reverse blocking state to the forward conduction state because of the special depletion layer variation mechanism depending on the 3D PBL.All the simulation results show that the novel UHV 3D-PBL MPS has excellent device performance.
基金the National Research and Development Program for Major Research Instruments of China(Grant No.62027814)the National Natural Science Foundation of China(Grant No.61904045)Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ20F040004)。
文摘A method to improve the surge current capability of silicon carbide(SiC)merged PiN Schottky(MPS)diodes is presented and investigated via three-dimensional electro-thermal simulations.When compared with a conventional MPS diode,the proposed structure has a more uniform current distribution during bipolar conduction due to the help of the continuous P+surface,which can avoid the formation of local hotspots during the surge process.The Silvaco simulation results show that the proposed structure has a 20.29%higher surge capability and a 15.06%higher surge energy compared with a conventional MPS diode.The bipolar on-state voltage of the proposed structure is 4.69 V,which is 56.29%lower than that of a conventional MPS diode,enabling the device to enter the bipolar mode earlier during the surge process.Furthermore,the proposed structure can suppress the occurrence of‘snapback'phenomena when switching from the unipolar to the bipolar operation mode.In addition,an analysis of the surge process of MPS diodes is carried out in detail.
基金the National Natural Science Foundation of China(60773218)the Natural Science Foundation of Liaoning Province (20072031)
文摘Aiming at the problem of merging heterogeneous semantic taxonomy emerged in Web information integration, a method of building Web classification ontology (WCO) has been proposed. A WCO that is logically consistent with the suggested upper merged ontology (SUMO) is defined, together with axioms needed to classify Web pages. WCO can be used as a foundation of merging heterogeneous semantic taxonomy, and could be used to support Web information integration and classification based Web information retrieval.
基金sponsored by the technological innovation projects of the National Administration of Surveying,Mapping and Geoinformation of ChinaNational Natural Science Foundations of China (Nos.41574003,41774004 and 41474015)Special Funds for Surveying,Mapping and Geoinformation Scientific Research in the Public Interest of China
文摘Employing the merged quasi-geoid, we analyses the causes of systematic errors in modelling of quasigeoid of neighbouring areas in the paper, and the efficient method is introduced to improve the accuracy of quasi-geoid. First, the systematic error is weakened with the moving window method applied to established quasi-geoids in two adjacent regions, and the accuracy of the merged quasi-geoid in the stitching region is checked using the measured GPS benchmark data; Second, the whole quasi-geoid is recomputed with data obtained from two adjacent regions if the accuracy of the quasi-geoid obtained from the first step in the stitching region is low; Finally, the quasi-geoids in two adjacent regions are recomputed respectively using GPS benchmark data of own region and adjacent region with the same solution if the accuracy of whole quasi-geoid obtained from the second step also is low. Actual data sets from Sichuan Province and Chongqing City are employed to test the moving window method. It is shown that the quasi-geoid models with high resolution and accuracy were obtained.
文摘Apreludial step of the current drive for structural adjustment in the CAS system, the establishment of Xinjiang Institute of Ecology & Geography was announced on July 7, 1998. The new institute is to incorporate the research resources of two former CAS institutes in the region in a bid to concentrate scattered R&D expertise and promote the interdependence of different disciplines in the implementation of national program
文摘Martens proposed a highly efficient and simply formed DFT algorithm——RCFA,whose efficien-cy is comparable with that of WFTA or that of PFA,and whose structure is similar to that of FFT.Theauthors have proved that,in the case of radix 2,the RCFA is exactly equivalent to the twiddle factor mergedfrequency-decimal FFT algorithm.The twiddle factor merged time-decimal FFT algorithm is providedin this paper.Thus,in any case,the FFT algorithm used currently can be replaced by the more efficientalgorithm——the twiddle factor merged FFT algorithm,with exactly the same external property and thesimilar internal structure.Also in this paper,the software for implementing the twiddle factor merged FFTalgorithm(TMFFT)is provided.
文摘The purpose of this paper is to evaluate the result of merge three companies.The researcher has examined the merge case through the collected information from three senior managers.The financial losses and mismanagement(after the merge)are the critical problems of the merge.The best solution is proper planning.A business plan can help companies to achieve their priorities.The operations deliver high performance by managerial processes that performance in the long-term.Moreover,the company shall care of employees through defining companies’capabilities.The professional management will have a direct positive effect on the company’s performance while unprofessional management will have a negative impact on company performance—also,the unprofessional merge negative effect in leading the company to success.
文摘目的:对比三维多回波恢复梯度回波(3D MERGE)、三维可变反转角快速自旋回波(3D SPACE STIR)序列在腰椎间盘突出症(LDH)检查中的应用效果。方法:选择2020年1月~2022年11月收治的135例LDH患者,回顾性分析患者临床和磁共振成像(MRI)资料,所有患者均接受常规MRI扫描及3D MERGE、3D SPACE STIR序列扫描,对比3D MERGE、3D SPACE STIR序列测量神经根直径的一致性,评价两种序列的图像质量参数[信噪比(SNR)、对比噪声比(CNR)]、图像清晰度评分。结果:3D MERGE和3D SPACE STIR序列测量的L3~S1神经根直径比较差异无统计学意义(P>0.05),且两组序列测量的L3、L4、L5和S1直径均显示出较高相关性(r=0.957,0.986,0.975,0.972,P<0.05);3D MERGE序列的SNR及CNR均高于3D SPACE STIR序列,神经根显示分级、图像清晰度评分优于3D SPACE STIR序列,差异有统计学意义(P<0.05)。结论:3D MERGE、3D SPACE STIR序列在LDH神经根直径测量中具有极高一致性,3D MERGE序列较3D SPACE STIR序列能够更清晰显示神经跟的解剖形态,图像质量更好。
文摘在循证医学时代下,依托规范的技术方法和标准化的操作规程发掘中医药独特优势,是实现中医药现代化、国际化发展并惠泽人类的必由之路。中医理论、人用经验和研究证据三结合证据体系的提出标志着中医药特色评价体系思维方法取得了重要进步,经过恰当方法整合后的多元证据体是中医药临床指南推荐意见和循证卫生决策的有力支撑。本文基于当前国际证据合成与分级方法学前沿进展,初步提出中医药多元证据整合的方法学框架——MERGE(Merge Evidence-based Research and artificial intelliGence to support smart dEcision)框架,以期为中医药循证医学方法学体系的完善和发展提供借鉴和参考。