An integrated split and dummy gates MOSFET with fast turn-off and reverse recovery characteristics

A power MOSFET with integrated split gate and dummy gate(SD-MOS) is proposed and demonstrated by the TCAD SENTAURUS.The split gate is surrounded by the source and shielded by the dummy gate.Consequently,the coupling area between the split gate and the drain electrode is reduced,thus the gate-to-drain charge(Q_(GD)),reverse transfer capacitance(C_(RSS)) and turn-off loss(E_(off)) are significantly decreased.Moreover,the MOS-channel diode is controlled by the dummy gate with ultra-thin gate oxide t_(ox),which can be turned on before the parasitic P-base/N-drift diode at the reverse conduction,then the majority carriers are injected to the N-drift to attenuate the minority injection.Therefore,the reverse recovery charge(Q_(RR)),time(T_(RR)) and peak current(I_(RRM)) are effectively reduced at the reverse freewheeling state.Additionally,the specific on-resistance(R_(on,sp)) and breakdown voltage(BV) are also studied to evaluate the static properties of the proposed SD-MOS.The simulation results show that the Q_(GD) of 6 nC/cm^(2),the C_(RSS) of 1.1 pF/cm^(2) at the V_(DS) of 150 V,the QRR of 1.2 μC/cm^(2) and the R_(on,sp) of 8.4 mΩ·cm^(2) are obtained,thus the figures of merit(FOM) including Q_(GD) ×R_(on,sp) of50 nC·mΩ,E_(off) × R_(on,sp) of 0.59 mJ·mΩ and the Q_(RR) × R_(on,sp) of 10.1 μC·mΩ are achieved for the proposed SD-MOS.

Strip segmentation of oceanic internal waves in SAR images based on TransUNet

The development of oceanic remote sensing artificial intelligence has made possible to obtain valuable information from amounts of massive data.Oceanic internal waves play a crucial role in oceanic activity.To obtain oceanic internal wave stripes from synthetic aperture radar(SAR)images,a stripe segmentation algorithm is proposed based on the TransUNet framework,which is a combination of U-Net and Transformer,which is also optimized.Through adjusting the number of Transformer layer,multi-layer perceptron(MLP)channel,and Dropout parameters,the influence of over-fitting on accuracy is significantly weakened,which is more conducive to segmenting lightweight oceanic internal waves.The results show that the optimized algorithm can accurately segment oceanic internal wave stripes.Moreover,the optimized algorithm can be trained on a microcomputer,thus reducing the research threshold.The proposed algorithm can also change the complexity of the model to adapt it to different date scales.Therefore,TransUNet has immense potential for segmenting oceanic internal waves.

In silico curation of QTL-rich clusters and candidate gene identification for plant height of bread wheat

Many genetic loci for wheat plant height(PH) have been reported, and 26 dwarfing genes have been catalogued. To identify major and stable genetic loci for PH, here we thoroughly summarized these functionally or genetic verified dwarfing loci from QTL linkage analysis and genome-wide association study published from 2003 to 2022. A total of 332 QTL, 270 GWAS loci and 83 genes for PH were integrated onto chromosomes according to their locations in the IWGSC RefSeq v2.1 and 65 QTL-rich clusters(QRC) were defined. Candidate genes in each QRC were predicted based on IWGSC Annotation v2.1 and the information on functional validation of homologous genes in other species. A total of 38 candidate genes were predicted for 65 QRC including three GA2ox genes in QRC-4B-IV, QRC-5A-VIII and QRC-6A-II(Rht24) as well as GA 20-oxidase 2(TaSD1-3A) in QRC-3A-IV. These outcomes lay concrete foundations for mapbased cloning of wheat dwarfing genes and application in breeding.

Comparison of the Δ^(12) fatty acid desaturase gene between high-oleic and normal-oleic peanut genotypes

Δ12 fatty acid desaturase gene has been targeted as a logical candidate controlling the high oleate trait in peanut seeds.By RT-PCR method,the full-length cDNAs of Δ12 fatty acid desaturase gene were isolated from peanut(Arachis hypogaea L.) genotypes with normal and high ratio of oleic to linoleic acid,which were designated AhFAD2B and AhFAD2B',respectively.Sequence alignment of their coding regions revealed that an extra A was inserted at the position +442 bp of AhFAD2B' sequence of high oleic acid genotypes,which resulted in the shift of open reading frame and a truncated protein AhFAD2B',with the loss of one histidine box involved in metal ion complex required for the reduction of oxygen.Analysis of transcript level showed that the expression of Δ12 fatty acid desaturase gene in high oleic acid genotype was slightly lower than that in normal genotype.The enzyme activity experiment of yeast(Saccharomyces cerevisiae) cell transformed with AhFAD2B or AhFAD2B' proved that only AhFAD2B gene product showed significant Δ12 fatty acid desaturase activity,but AhFAD2B' gene product did not.These results suggested that the change of AhFAD2B' gene sequence resulted in lower activity or deactivation of Δ12 fatty acid desaturase in high oleic acid genotype.

Assessment of genetic variation in tomato (Solanum lycopersicum L.) inbred lines using SSR molecular markers

A study was conducted to determine the genetic diversity of 39 determinate and indeterminate tomato inbred lines collected from China,Japan,S. Korea,and USA. Using 35 SSR polymorphic markers,a total of 150 alleles were found with moderate levels of diversity,and a high number of unique alleles existing in these tomato lines. The mean number of alleles per locus was 4.3 and the average poly-morphism information content (PIC) was 0.31. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) clustering at genetic similarity value of 0.85 grouped the inbred lines into four groups,where one USA cultivar formed a separate and more distant cluster. The most similar inbred lines are from USA,both with determinate type,whereas the most different lines are from USA (Us-16) and Japan (Ja-2) with determinate and indeterminate growth habit,respectively. Clustering was consistent with the known information regarding geographical location and growth habit. The genetic distance information reported in this study might be used by breeders when planning future crosses among these inbred lines.

COATS:Comprehensive observation on the atmospheric boundary layer three-dimensional structure during haze pollution in the North China Plain

The North China Plain(NCP)is troubled by severe haze pollution and the evolution of haze pollution is closely related to the atmospheric boundary layer(ABL).However,experimental and theoretical studies on the physical-chemical processes of the ABL in the NCP are lacking,with many scientific problems to be addressed.To solve these problems,the Comprehensive Observation on the Atmospheric boundary layer Three-dimensional Structure(COATS)during haze pollution was carried out in the NCP from 2016 to 2020.The COATS experiment adopted a"point-line-surface"spatial layout,obtaining both spatial-temporal profiles of the meteorological and environmental elements in the ABL and the turbulent transport data of fine particulate matter(PM_(2.5))in winter and summer.The research achievements are as follows.The spatial-temporal distribution characteristics of the ABL structure and PM_(2.5)concentrations in NCP were determined.The typical thermal structure of persistent heavy haze events and the pollutant removal mechanism by low-level jets were revealed.It was determined that the spatial structure of the ABL adjusted by the Taihang Mountains is responsible for the heterogeneous distribution of haze pollution in the NCP,and that mountain-induced vertical circulations can promote the formation of elevated pollution layers.The restraints of the atmospheric internal boundaries on horizontal diffusion of pollutants were emphasized.The contribution of the ABL to haze pollution in winter and summer was qualitatively compared and quantitatively estimated.The turbulent transport nature behind the relationship between the atmospheric boundary layer height(ABLH)and surface PM_(2.5)concentrations was analyzed.The concept of"aerosol accumulation layer"was defined,and the applicability of the material method in determining ABLH was clarified.A measurement system for obtaining the turbulent flux of PM_(2.5)concentrations was developed,and the turbulence characteristics of PM_(2.5)concentrations were demonstrated.The COATS experiment is of great theoretical significance for thoroughly understanding the physical mechanisms of the ABL during haze pollution and filling the knowledge gap on the impacts of the ABL three-dimensional structure on haze pollution.The results of this study are conducive to the improvement and development of ABL parameterization schemes and serve as a scientific basis for formulating regional pollution prevention and control measures.

Gravitational quasinormal modes of a parametrized Schwarzschild metric

Recently,a parametrized Schwarzschild metric(PSM)was proposed,in which n=2 to solve the differences of mass of M87*from different observations.We find the axial gravitational quasinormal modes of this metric are unstable for n>1.The decay rate of the quasinormal mode of the case n<1 is much smaller than the case n=1,which can be used to differentiate the PSM from a Schwarzschild one.

Energy in critical collapse

We study the energy issue in critical collapse.It is found that in critical collapse,the contribution from the material energy is greater than that from the gravitational energy.The quantity m/r plays an important role in identifying the formation of an apparent horizon in gravitational collapse,where m is the Misner-Sharp mass and r is the areal radius.We observe that in critical collapse,the maximum value of m/r fluctuates between 2/15 and 4/15.This denotes a large gap between critical collapse and black hole formation for which the criterion is m/r=1/2.

影响我国霾天气的多尺度过程

频发的霾天气是我国现阶段面临的最主要大气环境问题之一.霾期间高浓度大气细颗粒物(PM2.5)是多种物理化学过程综合影响的结果,包括排放、气-粒转化、大气边界层、局地环流、天气与气候等过程.上述过程的时空尺度跨越了几个数量级,在空间尺度上涵盖了纳米尺度至上千千米尺度.多尺度过程本身的复杂性以及不同过程之间的相互影响是目前大气环境领域面临的最严峻挑战,直接影响到对于霾天气形成机制的科学认识、预报技术与数值模式研发,以及相应的大气污染治理.文章综述了在影响我国霾天气的多尺度过程及其与气溶胶的相互作用领域取得的研究进展.研究表明:二次气溶胶已经成为我国大气气溶胶的主要部分,在霾过程后期,液相非均相过程对气-粒转化有重要贡献;PM2.5呈现多时间尺度周期性振荡,包括1,4~7以及40~60 d等,边界层、天气和气候等多尺度过程是造成上述周期性变化的主因;已有证据表明,我国高气溶胶已经影响到该区域大气光化学、大气边界层,甚至天气和气候过程.气溶胶与上述过程的相互作用进一步影响了气溶胶浓度及其空间分布,但是此问题极为复杂,尚存在很大不确定性.为此,今后需重点加强以下研究:加强包含气溶胶理化性质、大气光化学、气象要素在内的多要素协同观测,重点开展对流层内多要素协同垂直探测;增强跨学科领域研究,尤其是大气物理-大气化学-天气/气候等多学科间的交叉性研究;加强气溶胶与大气化学、边界层、天气气候等过程相互作用的数值模拟研究.

Identification and characterization of putative CIPK genes in maize

当在细胞内部的发信号的第二个送信人由发展、环境的暗示得到了，钙(Ca ) 起一个关键作用。Calcineurin 象 B 一样蛋白质(CBL ) 和他们的目标蛋白质，交往 CBL 蛋白质 kinases (CIPK ) 在植物响应压力作为一个关键调停 Ca2+ 的发信号网络出现了。生物信息的分析被用来识别 43 通常认为的 ZmCIPK (Zea mays CIPK ) 在玉米的染色体的基因生来的线 B73。基于基因结构，这些 ZmCIPKs 被划分成 intron 富有、 intron 差的组。种系发生的分析显示 ZmCIPK 家庭与 30 个成员的米饭 CIPK 家庭一起有一种高进化的关系。Microarray 数据和 RT-PCR 试金显示出基因 transcriptionally 回答了到不能生活的压力，和基因是的那 24， 31， 20 和 19 ZmCIPK 的那 ZmCIPK 由盐，干旱，热和冷压力起来调整分别地。在冷应力下面有在寒冷容忍的生来的线 B73 和寒冷敏感的生来的线 Mo17 之间的 ZmCIPKs 的不同表示模式。我们的调查结果将在玉米帮助 CIPK 的生物功能的进一步分子的解剖，并且提供新卓见进在植物表明网络的 CBLCIPK。

Policy Analysis and Development Evaluation of Digital Trade:An International Comparison

As an extension of traditional trade,digital trade is a new type of trade in the era of the digital economy.In this paper,we first analyze the digital trade-related strategies of eight leading economies through word clouds and dissect China s digital trade-related policies using the word frequency method by sorting through the digital trade-related policy documents of 26 economies and Chinese provinces.We then evaluate the status quo of digital trade development in 111 countries and Chinese provinces by building a digital trade index system to determine the development environment and market potential.The results show that all countries attach great importance to digital technology,data and government guidance in the development of digital trade.The results also reveal that"development,""service"and"construction"are the three most frequently used words in various Chinese documents.The overall level of China s digital trade is at the global vanguard,but is characterized by uneven regional development.In the era of digital trade,traditional international trade theory is also in urgent need of breakthroughs and innovation.

Assessment of genetic diversity in broomcorn millet (Panicum miliaceum L.) using SSR markers

The genetic diversity of 118 accessions of broomcorn millet(Panicum miliaceum L.),collected from various ecological areas,was analyzed.Using 46 SSR(Simple Sequence Repeat) polymorphic markers from rice,wheat,oat and barley,a total of 226 alleles were found,which exhibited moderate level of diversity.The number of alleles per primer ranged from two to nine,with an average of 4.91.The range of polymorphism information content(PIC) was 0.284-0.980(average,0.793).The expected heterozygosity(He) varied from 0.346 to 0.989,with an average of 0.834.The average coefficient of the genetic similarity of SSR markers among the 118 accessions was 0.609,and it ranged from 0.461 to 0.851.The UPGMA(Unweight Pair Group Method with Arithmetic Mean) clustering analysis at the genetic similarity value of 0.609 grouped the 118 accessions into five groups.Mantel test meant that geographical origin and genetic distance presented positive correlation.The clustering results were consistent with known information on ecological growing areas.The genetic similarity coefficient of the accessions in the Loess Plateau ecotype was significantly lower than those in the other ecotypes.It indicates that the highest level of genetic diversity occurred in the Loess Plateau,which is probably the original site of Panicum miliaceum.

Characteristics of Boundary Layer Structure during a Persistent Haze Event in the Central Liaoning City Cluster, Northeast China

The characteristics of boundary layer structure during a persistent regional haze event over the central Liaoning city cluster of Northeast China from 16 to 21 December 2016 were investigated based on the measurements of particulate matter(PM) concentration and the meteorological data within the atmospheric boundary layer(ABL). During the observational period, the maximum hourly mean PM_(2.5) and PM10 concentrations in Shenyang, Anshan, Fushun, and Benxi ranged from 276 to 355 μg m–3 and from 378 to 442 μg m–3, respectively, and the lowest hourly mean atmospheric visibility(VIS) in different cities ranged from 0.14 to 0.64 km. The central Liaoning city cluster was located in the front of a slowly moving high pressure and was mainly controlled by southerly winds. Wind speed(WS) within the ABL(< 2 km) decreased significantly and WS at 10-m height mostly remained below 2 m s–1 during the hazy episodes, which was favorable for the accumulation of air pollutants. A potential temperature inversion layer existed throughout the entire ABL during the earlier hazy episode [from 0500 Local Time(LT) 18 December to 1100 LT 19 December], and then a potential temperature inversion layer developed with the bottom gradually decreased from 900 m to 300 m. Such a stable atmospheric stratification further weakened pollutant dispersion. The atmospheric boundary layer height(ABLH) estimated based on potential temperature profiles was mostly lower than 400 m and varied oppositely with PM_(2.5) in Shenyang. In summary, weak winds due to calm synoptic conditions, strong thermal inversion layer, and shallow atmospheric boundary layer contributed to the formation and development of this haze event.The backward trajectory analysis revealed the sources of air masses and explained the different characteristics of the haze episodes in the four cities.

Characteristics of Turbulent Transfer during Episodes of Heavy Haze Pollution in Beijing in Winter 2016/17

We analyzed the structure and evolution of turbulent transfer and the wind profile in the atmospheric boundary layer in relation to aerosol concentrations during an episode of heavy haze pollution from 6 December 2016 to 9 January 2017. The turbulence data were recorded at Peking University's atmospheric science and environment observation station. The results showed a negative correlation between the wind speed and the PM2.5 concentration. The turbulence kinetic energy was large and showed obvious diurnal variations during unpolluted(clean) weather, but was small during episodes of heavy haze pollution. Under both clean and heavy haze conditions, the relation between the non-dimensional wind components and the stability parameter z/L followed a 1/3 power law, but the normalized standard deviations of the wind speed were smaller during heavy pollution events than during clean periods under near-neutral conditions. Under unstable conditions, the normalized standard deviation of the potential temperatureσ_θ/|θ_*| was related to z/L, roughly following a –1/3 power law, and the ratio during pollution days was greater than that during clean days. The three-dimensional turbulence energy spectra satisfied a –2/3 power exponent rate in the high-frequency band. In the low-frequency band, the wind velocity spectrum curve was related to the stability parameters under clear conditions, but was not related to atmospheric stratification under polluted conditions. In the dissipation stage of the heavy pollution episode, the horizontal wind speed first started to increase at high altitudes and then gradually decreased at lower altitudes. The strong upward motion during this stage was an important dynamic factor in the dissipation of the heavy haze.

Review of Chinese atmospheric science research over the past 70 years: Atmospheric physics and atmospheric environment

Since the founding of the People’s Republic of China 70 years ago,the subject of atmospheric physics and atmospheric environment has developed rapidly in China,providing important support for the development of atmospheric science and guarantee for the development of national economy.In this paper,the general advancement of atmospheric physics and atmospheric environment in last 70 years was described.The main research progress of atmospheric physics and atmospheric environment in the past 40 years of reform and opening-up was reviewed,the outstanding research achievements since the 21 st century were summarized,the major problems and challenges are pointed out,and the key directions and suggestions for future development are put forward.

A study on atmospheric turbulence structure and intermittency during heavy haze pollution in the Beijing area

In this study,the characteristics of turbulence transport and intermittency and the evolutionary mechanisms were studied in different pollution stages of heavy haze weather from December 2016 to January 2017 in the Beijing area using the method developed by Ren et al.(2019)as the automatic identification of atmospheric spectral gaps and the reconstruction of atmospheric turbulence sequences.The results reveal that turbulence intermittency is the strongest in the cumulative stage(CS)of heavy haze weather,followed by in the transport stage(TS),and it is the weakest in the dissipation stage(DS).During the development and accumulation of haze pollution,buoyancy contributes negatively to turbulent kinetic energy(TKE),and horizontal wind speed is low.The classical turbulent motion is often affected by submesoscale motion.As a result,the calculation results of turbulence parameters are affected by submesoscale motion,which causes intensified turbulence intermittency.During the dissipation of pollution,the downward momentum transfer induced by low-level jets provides kinetic energy for turbulent motion in the near surface layer.The turbulent mixing effect is enhanced,and intermittency is weakened.Due to the intermittency of atmospheric turbulence,turbulence parameters calculated from the original fluctuation of meteorological elements may be overestimated.The overestimation of turbulence parameters in the CS is the strongest,followed by the TS,and the DS is the weakest.The overestimation of turbulent fluxes results in an overestimation of atmospheric dissipation capability that may cause an underestimation of pollutant concentrations in the numerical simulations of air quality.

Influence of Intermittent Turbulence on Air Pollution and Its Dispersion in Winter 2016/2017 over Beijing, China

With rapid urbanization in recent years,severe air pollution has emerged as a major issue for many regions of China,especially in some metropolises.A persistent pollution case during 6 December 2016–8 January 2017 was selected to investigate the relations between turbulent intermittency and frequent PM2.5(particulate matters with diameter less than 2.5μm)pollution events over the metropolitan region of Beijing,China.The accumulation of PM2.5 near the surface frequently occurred as a combined result of strong inversion layers,stagnant winds,high ambient humidity levels,and stable stratification during this case.Arbitrary-order Hilbert spectral analysis indicated that steep decreases in the PM2.5 concentration were simultaneous with the occurrence of intermittent turbulence and strong vertical mixing.A wind profiler observation revealed existence of low-level jets(LLJs)at the end of the polluted periods,suggesting that the upper-level turbulent mixing accompanied by the wind shear of LLJ was transported downward and enhanced the vertical mixing near the surface,which might have caused an abrupt reduction in PM2.5 and improvement in air conditions.

Recent active thermal management technologies for the development of energy-optimized aerospace vehicles in China

Recently, the development of modern vehicles has brought about aggressive integration and miniaturization of on-board electrical and electronic devices. It will lead to exponential growth in both the overall waste heat and heat flux to be dissipated to maintain the devices within a safe temperature range. However, both the total heat sinks aboard and the cooling capacity of currently utilized thermal control strategy are severely limited, which threatens the lifetime of the on-board equipment and even the entire flight system and shrink the vehicle’s flight time and range. Facing these thermal challenges, the USA proposed the program of "INVENT" to maximize utilities of the available heat sinks and enhance the cooling ability of thermal control strategies. Following the efforts done by the USA researchers, scientists in China fought their ways to develop thermal management technologies for Chinese advanced energy-optimized airplanes and spacecraft. This paper elaborates the available on-board heat sinks and aerospace thermal management systems using both active and passive technologies not confined to the technology in China. Subsequently, active thermal management technologies in China including fuel thermal management system, environment control system, non-fuel liquid cooling strategy are reviewed. At last, space thermal control technologies used in Chinese Space Station and Chang’e-3 and to be used in Chang’e-5 are introduced.Key issues to be solved are also identified, which could facilitate the development of aerospace thermal control techniques across the world.

Research Progress on Estimation of the Atmospheric Boundary Layer Height

Atmospheric boundary layer height(ABLH)is an important parameter used to depict characteristics of the planetary boundary layer(PBL)in the lower troposphere.The ABLH is strongly associated with the vertical distributions of heat,mass,and energy in the PBL,and it is a key quantity in numerical simulation of the PBL and plays an essential role in atmospheric environmental assessment.In this paper,various definitions and methods for deriving and estimating the ABLH are summarized,from the perspectives of turbulent motion,PBL dynamics and thermodynamics,and distributions of various substances in the PBL.Different methods for determining the ABLH by means of direct observation and remote sensing retrieval are reviewed,and comparisons of the advantages and disadvantages of these methods are presented.The paper also summarizes the ABLH parameterization schemes,discusses current problems in the estimation of ABLH,and finally points out the directions for possible future breakthroughs in the ABLHrelated research and application.