Rapid rupture characterization for the 2023 M_(S)6.2 Jishishan earthquake

On December 18, 2023, the M_(S)6.2 Jishishan earthquake occurred in the northeastern region of the QinghaiXizang Plateau, causing heavy casualties and property damage in Gansu and Qinghai Provinces. In this study,we integrate space imaging geodesy, finite fault inversion, and back-projection methods to decipher its rupture property, including fault geometry, coseismic slip distribution, rupture direction, and propagation speed. The results reveal that the seismogenic fault dips to the southwest at an angle of 29°. The major slip asperity is dominated by reverse slip and is concentrated within a depth range of 7–16 km, which explains the significant uplift near the epicenter observed by both the Sentinel-1 ascending and descending In SAR data. Moreover, the teleseismic array waveforms indicate a northwest propagating rupture with an overall slow rupture velocity of~1.91 km/s(AK array) or 1.01 km/s(AU array).

A Review of Atmospheric Electricity Research in China from 2019 to 2022

Atmospheric electricity is composed of a series of electric phenomena in the atmosphere.Significant advances in atmospheric electricity research conducted in China have been achieved in recent years.In this paper,the research progress on atmospheric electricity achieved in China during 2019-22 is reviewed focusing on the following aspects:(1)lightning detection and location techniques,(2)thunderstorm electricity,(3)lightning forecasting methods and techniques,(4)physical processes of lightning discharge,(5)high energy emissions and effects of thunderstorms on the upper atmosphere,and(6)the effect of aerosol on lightning.

Reliability Analysis of Satellite Turntable System under Multiple Operation Modes Based on Multi-Valued Decision Diagrams

As a payload support system deployed on satellites,the turntable system is often switched among different working modes during the on-orbit operation,which can experience great state changes.In each mode,the missions to be completed are different,consecutive and non-over-lapping,from which the turntable system can be considered to be a phased-mission system(PMS).Reliability analysis for PMS has been widely studied.However,the system mode cycle characteristic has not been taken into account before.In this paper,reliability analysis method of the satellite turntable system is proposed considering its multiple operation modes and mode cycle characteristic.Firstly,the multi-valued decision diagrams(MDD)manipulation rules between two adjacent mission cycles are proposed.On this basis,MDD models for the turntable system in different states are established and the reliability is calculated using the continuous time Markov chains(CTMC)method.Finally,the comparative study is carried out to show the effectiveness of our proposed method.

Climatology of Lightning Activity in South China and Its Relationships to Precipitation and Convective Available Potential Energy

This study examined lightning activity and its relationship to precipitation and convective available potential energy （CAPE） in South China during 2001-12, based on data from the Guangdong Lightning Location System, the Tropical Rainfall Measuring Mission satellite, and the ERA-Interim dataset. Two areas of high lightning density are identified： one over the Pearl River Delta, and the other to the north of Leizhou Peninsula. Large peak-current cloud-to-ground （LPCCG） lightning （〉75 kA） shows weaker land-offshore contrasts than total CG lightning, in which negative cloud-to-ground （NCG） lightning occurs more prominently than positive cloud-to-ground （PCG） lightning on land, While the frequency of total CG lightning shows a main peak in June and a second peak in August, the LPCCG lightning over land shows only a single peak in June. The ratio of positive LPCCG to total lightning is significantly greater during February-April than during other times of the year. Diurnally, CG lightning over land shows only one peak in the afternoon, whereas CG lightning offshore shows morning and afternoon peaks. The rain yield per flash is on the order of 107-108 kg per flash across the analysis region, and its spatial distribution is opposite to that of lightning density. Our data show that lightning activity over land is more sensitive than that over offshore waters to CAPE. The relationships between lightning activity and both precipitation and CAPE are associated with convection activity in the analysis region.

A Review of Atmospheric Electricity Research in China from 2011 to 2018

Atmospheric electricity research has been conducted actively in China,having profited from the development and application of high temporal and spatial resolution lightning detection and location technologies.This paper reviews the scientific advances made in the field of atmospheric electricity in China from 2011 to 2018,covering the following five aspects:(1)lightning detection and location techniques;(2)discharge processes and parameters associated with rocket-triggered lightning;(3)physical processes in natural lightning and attachment to the ground;(4)lightning activities and charge structure in different thunderstorms;and(5)effects of thunderstorms on the upper atmosphere.In addition,some outstanding questions for future research are outlined.

A Physical Layer Algorithm for Estimation of Number of Tags in UHF RFID Anti-Collision Design

A priori knowledge of the number of tags is crucial for anti-collision protocols in slotted UHF RFID systems.The number of tags is used to decide optimal frame length in dynamic frame slotted ALOHA(DFSA)and to adjust access probability in random access protocols.Conventional researches estimate the number of tags in MAC layer based on statistics of empty slots,collided slots and successful slots.Usually,a collision detection algorithm is employed to determine types of time slots.Only three types are distinguished because of lack of ability to detect the number of tags in single time slot.In this paper,a physical layer algorithm is proposed to detect the number of tags in a collided slot.Mean shift algorithm is utilized,and some properties of backscatter signals are investigated.Simulation results verify the effectiveness of the proposed solution in terms of low estimation error with a high SNR range,outperforming the existing MAC layer approaches.

Analysis of the Spectral Characteristics of Triggered Lightning

The spectra with wavelength range of 390 nm to 660 nm of triggered lightning were observed in Guangdong Area using a slitless spectrograph. The characteristics of the lightning spectra during the initial continuous current and return strokes were analyzed, and the differences between the metal section and air section of the lightning channel were compared. The results showed that the metal spectra were contained in the metal section during the initial continuous current. As for the lightning channel of the return strokes, the line spectra for both the metal section and the air section were identical;neither of the two sections contained the metal spectra, but the relative intensity of its emission spectrum was different. Owing to different radiation mechanisms, the spectral structures and luminance of the two sections were not the same. Combined with the current data, it was found that there was a good positive correlation between the total spectral strength and the transferred charge. The total intensity of the lightning channel spectrum increased with the height of the channel, indicating that the radiation sequence of the lightning channel was different. High temporal resolution observations showed that the spectral line duration could be divided into three categories, in which the lines with higher excitation energy appear first and decay rapidly, while those with lower excitation energy appear later but last longer.

Stability and output feedback stabilization for systems with Markovian switching and impulse effects

We investigate the exponential stability in the mean square sense for the systems with Markovian switching and impulse effects.Based on the statistic property of the Markov process,a stability criterion is established.Then,by the parameterizations via a family of auxiliary matrices,the dynamical output feedback controller can be solved via an LMI approach,which makes the closed-loop system exponentially stable.A numerical example is given to demonstrate the method.

Analysis of Chinese A gricultural Product Trade

This paper clarifies thestatus of Chinese agricultural product trade through the calculation of Chinese agricultural product trade competitive advantage index for a total of 21 years from 1999 to 2019.

Optimizing strain response in lead-free(Bi_(0.5)Na_(0.5))TiO_(3)-BaTiO_(3)-NaNbO_(3)solid solutions via ferroelectric/(non-)ergodic relaxor phase boundary engineering

Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.

Recent observations and research progresses of terrestrial gamma-ray flashes during thunderstorms

Terrestrial gamma-ray flashes(TGFs)are high-energy emissions in thunderstorms that were discovered first by satellite-based and then by ground-based gamma-ray detectors with photon energy up to tens of Me V.TGFs are a natural highenergy phenomenon associated with lightning discharges that frequently occur during thunderstorms.However,their production mechanisms and associated processes are still unclear.TGF studies have already been a research spotlight in the atmospheric electricity and high-energy atmosphere research areas.In this paper,we review recent research progresses on TGF studies in the past decade,including TGF detection,the relationship between TGFs and lightning processes,and thunderstorm activities.Several unsolved important scientific questions are discussed.Results suggest that upward TGFs observed by satellite-based detectors are closely connected with the development of in-cloud upward negative leaders.They are usually generated in milliseconds of the initiation of upward negative leaders and may produce a kind of distinct radio emissions because of the generation and propagation of huge amounts of high-energy electrons.By contrast,its counterpart,i.e.,downward TGFs observed by ground-based gamma-ray detectors,is associated with different types of lightning processes,such as downward negative or upward positive leaders,the initial continuing current stage of rocket-triggered lightning flashes return stroke processes.Because of limited observations,how these downward TGFs are generated is still unclear.Benefiting from the development of state-of-the-art instruments with high temporal and spatial resolutions,new insights into the processes and mechanisms of TGFs will be achieved with coordinated observations from satellite-based and ground-based measurements.

Step-edge-guided nucleation and growth mode transition of α-Ga_(2)O_(3) heteroepitaxy on vicinal sapphire

Controlling the epitaxial growth mode of semiconductor layers is crucial for optimizing material properties and device performance.In this work,the growth mode ofα-Ga_(2)O_(3) heteroepitaxial layers was modulated by tuning miscut angles(θ)from 0°to 7°off the(1010)direction of sapphire(0002)substrate.On flat sapphire surfaces,the growth undergoes a typical three-dimensional(3D)growth mode due to the random nucleation on wide substrate terraces,as evidenced by the hillock morphology and high dislocation densities.As the miscut angle increases toθ=5°,the terrace width of sapphire substrate is comparable to the distance between neighboring nuclei,and consequently,the nucleation is guided by terrace edges,which energetically facilitates the growth mode transition into the desirable two-dimensional(2D)coherent growth.Consequently,the mean surface roughness decreases to only 0.62 nm,accompanied by a significant reduction in screw and edge dislocations to 0.16×10^(7) cm^(-2)and 3.58×10^(9) cm^(-2),respectively.However,the further increment of miscut angles toθ=7°shrink the terrace width less than nucleation distance,and the step-bunching growth mode is dominant.In this circumstance,the misfit strain is released in the initial growth stage,resulting in surface morphology degradation and increased dislocation densities.

Bidirectional propagation of lightning leader

The characteristics of initial leader of triggered lightning flashes are studied by use of a highspeed digital camera system with the rate of 1000 frame per second and simultaneous measurements of current and electric field change with 0.1 μs time resolution. The results show that the altitude-triggered lightning was initiated by bidirectional propagation leader because of 'current interruption' by air gap,whereas the grounded-triggered one was not. The onset of downward-moving positive leader was prior to that of the upward-going negative leader for 843 ms in an altitude-triggered lightning under the positive ambient electric field. The downward-moving leader, regardless of its polarity, would produce inhomogeneous distribution of luminosity (current) along the channel on the moment of connection to the ground.

FY-4A LMI Observed Lightning Activity in Super Typhoon Mangkhut(2018)in Comparison with WWLLN Data

Using lightning observations from the Fengyun-4A Lightning Mapping Imager(FY-4A LMI),best-track data from the Shanghai Typhoon Institute,bright temperature(TBB)data from Himawari-8 satellite,and composite reflectivity(CR)data from the South China radar network,we investigate the spatiotemporal distribution of lightning activity and convective evolution during the landfall of Super Typhoon Mangkhut,the strongest landing typhoon in China in2018.Three stages of active total lightning are observed,and differences of lightning characteristics between the inner core and the outer rainbands are present.The onset of inner-core lightning outbreak is about 4 h ahead of the maximum intensity of the storm,providing indicative information on the change of typhoon intensity.Lightning rates in the outer rainbands increase rapidly 12 h before the landfall,and lightning activity is mainly confined in the outer rainbands after the landfall.A good correlation in hourly variation is shown between lightning rates from the LMI and TBBs from the satellite.The averaged TBB within the inner core reaches its minimum(–80℃)when the innercore lightning outbreak occurs,indicating the occurrence and enhancement of deep convection there.Lightning locations observed by the LMI has a good spatial correspondence with regions of low TBBs and high CRs,revealing the monitoring capability of the LMI to lightning activity and deep convection in landing typhoons.Comparisons between the World Wide Lightning Location Network(WWLLN)and the LMI reveal that the spatial distribution,temporal evolution,and radial pattern of lightning activity in Mangkhut observed by the two systems are consistent.Furthermore,due to the detection capability of total lightning,the LMI has advantages in revealing the higher ratio of intra-cloud lightning within the inner core in typhoon.The continuous and real-time observation ofFY-4ALMI provides an unprecedented platform for monitoring total lightning and deep convection in landing typhoons in China,which will promote the generation of new research and applications in the future.

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.

Assimilation of Total Lightning Data Using the Three-Dimensional Variational Method at Convection-Allowing Resolution

A large number of observational analyses have shown that lightning data can be used to indicate areas of deep convection. It is important to assimilate observed lightning data into numerical models, so that more small-scale information can be incorporated to improve the quality of the initial condition and the subsequent forecasts. In this study, the empirical relationship between flash rate, water vapor mixing ratio, and graupel mixing ratio was used to adjust the model relative humidity, which was then assimilated by using the three-dimensional variational data assimilation system of the Weather Research and Forecasting model in cycling mode at 10-min intervals. To find the appropriate assimilation time-window length that yielded significant improvement in both the initial conditions and subsequent forecasts, four experiments with different assimilation time-window lengths were conducted for a squall line case that occurred on 10 July 2007 in North China. It was found that 60 min was the appropriate assimilation time-window length for this case, and longer assimilation window length was unnecessary since no further improvement was present. Forecasts of 1-h accumulated precipitation during the assimilation period and the subsequent 3-h accumulated precipitation were significantly improved compared with the control experiment without lightning data assimilation. The simulated reflectivity was optimal after 30 min of the forecast, it remained optimal during the following 42 min, and the positive effect from lightning data assimilation began to diminish after 72 min of the forecast. Overall,the improvement from lightning data assimilation can be maintained for about 3 h.

Simulation study of discharge processes in thunderstorm

The discharge characteristics in thunderstorm have been calculated by using a numerical cloud model. The results indicate that discharge processes occur when simulated thunderstorm developed at the stage of 30-45 min and initial locations of discharge mainly distributes between 4.4-4.8 km and 6.4-6.8 km above the ground (corresponding to ambient temperature of - 10℃ and -25℃. In simulated thunderstorm with a tripole electric structure,

Analysis of the relationship between bile duct and duodenal microbiota reveals that potential dysbacteriosis is the main cause of primary common bile duct stones

Bacteria play an important role in the formation of primary Common Bile Duct(CBD)stones.However,the composition and function of the microbiota of bile duct in patients with primary CBD stones remained to be explored.We utilized the 16S rRNA gene high-throughput sequencing technology to analyze the microbial diversity and community composition of biliary and duodenal microbiota in 15 patients with primary CBD stones and 4 patients without biliary tract diseases.Alpha diversity analysis showed that the microbiota richness was similar in bile and intestinal fluid;Beta diversity analysis showed that there were differences in the composition between biliary microbiota and the duodenal microbiota,but the abundance of the main groups showed similarities.The composition of the biliary microbiota from gallstone patients was more complex,as was the duodenal microbiota.Proteobacteria and Firmicutes were the dominant bacteria at phylum level,accounting for at least 75%of the total reads in each subgroup.Pseudomonas and EscherichiaShigella were the major genus among subgroups,but Escherichia-Shigella had increased abundance in duodenal microbiota with primary choledocholithiasis,which may play an important role in stone formation.It is noteworthy that Clostridiumsensu_stricto,Lachnospiraceae_UCG-008,Butyrivibrio and Roseburia which could produce short chain fatty acids(SCFAs),were significantly decreased in biliary microbiota with primary CBD stones(p<0.05).Our study provided new insights into the compositional of normal biliary microbiota.The micro-ecology of biliary and duodenal in patients with stones is complex and closely related,and there is a potential for dysbacteriosis.The decrease in abundance of certain major acid-producing bacteria affects the health of the biliary tract and thus leads to the formation of stones.

Understanding the dynamical-microphysical-electrical processes associated with severe thunderstorms over the Beijing metropolitan region

The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model.

Application of Lightning Data Assimilation to Numerical Forecast of Super Typhoon Haiyan (2013)

Previous observations from World Wide Lightning Location Network(WWLLN) and satellites have shown that typhoon-related lightning data have a potential to improve the forecast of typhoon intensity. The current study was aimed at investigating whether assimilating TC lightning data in numerical models can play such a role. For the case of Super Typhoon Haiyan in 2013, the lightning data assimilation(LDA) was realized in the Weather Research and Forecasting(WRF) model, and the impact of LDA on numerical prediction of Haiyan’s intensity was evaluated.Lightning data from WWLLN were used to adjust the model’s relative humidity(RH) based on the method developed by Dixon et al.(2016). The adjusted RH was output as a pseudo sounding observation, which was then assimilated into the WRF system by using the three-dimensional variational(3DVAR) method in the cycling mode at 1-h intervals. Sensitivity experiments showed that, for Super Typhoon Haiyan(2013), which was characterized by a high proportion of the inner-core(within 100 km from the typhoon center) lightning, assimilation of the inner-core lightning data significantly improved its intensity forecast, while assimilation of the lightning data in the rainbands(100–500 km from the typhoon center) led to no obvious improvement. The improvement became more evident with the increase in LDA cycles, and at least three or four LDA cycles were needed to achieve obvious intensity forecast improvement. Overall, the improvement in the intensity forecast by assimilation of the inner-core lightning data could be maintained for about 48 h. However, it should be noted that the LDA method in this study may have a negative effect when the simulated typhoon is stronger than the observed, since the LDA method cannot suppress the spurious convection.