The Effect Analysis of Topography on the Spectrum Properties of Anti-Plane Movement

An explicit finite difference method is performed to evaluate the significance of topography effects on the seismic response of viscoelastic sites. The real accelerograms and bell-shape impulse wavelets, slope angle of cliff and angle of incidence on the spectrum property of the incoming waves are all discussed in detail. The conclusions show that the presence of topographic factors and the direction of the incident waves not only significantly affect the peak ground acceleration of a site, but also affect the spectrum properties of the incoming waves, and the effect on the direction of the incident waves is especially remarkable. The study also finds that it is reasonable to analyse spectrum properties with the input of impulse wavelets in the finite element simulation of wave motion.     

APPLICATION OF NEURAL NETWORK IN FLOOD PREDICTION

IINTRODUCTIONIntherecentdecadesfrequentflooddisasterscausedseriousdamagesandclaimedthousandsoflives,suchasthe1998floodintheYangtzeRiverandthe1996floodintheYellowRiver.The1998floodintheYangtzeandtheSonghuaRiversbroughtdirectlossesofmorethan$30billions.Lowdischargehighstageisthemaincharacterofthefloods.Forexample,thehighestfloodstagein1998wasI.sinhigheranddischargewas14000m3/slowerthanthosein1954atLuoshanStationoftheVangtzeRiver.Anewmodelisrequiredtobedevelopedforaccuratepredictionoffl…     

Flavor Characteristics of Different Crops of Laver(Porphyra yezoensis)During One Harvest Cycle

The taste and odor analysis of the first,second,fourth and sixth crops of laver(Porphyra yezoensis)was obtained by electronic tongue,taste-related compound,electronic nose and gas chromatography-ion mobility spectrometer(GC-IMS).Through the detection of the electronic tongue,the pleasant tastes such as umami and richness are more intense in the early crops,which is consistent with the analysis results of free amino acids and flavored nucleotides.The electronic nose can clearly distinguish between different laver crops.GC-IMS separated and identified 36 volatile components from lavers,mainly including aldehydes,ketones,alcohols,esters,acids and aromatic substances.For the early harvested crops,nonanal,octanal,hexanal and benzaldehyde have a significant contribution to odor because of the high concentration and low threshold of these compounds.For the later harvested crops,the concentration of most ketones and some aldehydes increased.1-Octen-3-ol,malondialdehyde and heptanal constituted the main odor characteristics.     

Sedimentary Environments of the Cangfanggou Groupin Junggar Basin, Xinjiang, in Response toClimate and Tectonic Regime

Detailed studies of petrology, palaeocurrent direction, paiaeogeomorphology and palaeohydrody-namics have been conducted for the Permian-Triassic Cangfanggou Group in the foredeep of the Bogda Mountains in the southeastern Junggar Basin, Xinjiang. Sedimentary environments and fades of alluvial fans and pebbly braided rivers, sandy braided rivers, meandering rivers, low-sinuosity rivers, swamps and fresh-water lakes are recognized in the group. Climate and tectonics of source areas strongly controlled the evolution of the sedimentary environments and facies in the foredeep. The block faulting in the Bogda Mountains increased the ground slope, which led to a drastic increase in the grain size of the sediments. Humid climate, being beneficial to plant growth, would provide protection of channel banks and at the same time weaken chemical weathering in the source area, thus large amounts of clay materials are available for the formation of clay plugs. As a result, stable banks and meandering river belts are     

Simulation and Analysis of China Climate Using Two-Way Interactive Atmosphere-Vegetation Model （RIEMS-AVIM）

In this paper, an Atmosphere-Vegetation Interaction Model （AVIM） is coupled to the Regional Integrated Environment Model System （RIEMS）, and a 10-year integration for China is performed using the RIEMS-AVIM. The analysis of the results of the 10-year integration shows that the characters of the spatial distributions of temperature and precipitation over China are well simulated. The patterns of simulated surface sensible and latent heat fluxes match well with the spatial climatological atlas： the values of winter surface sensible and latent heat fluxes are both lower than climatological values over the whole country. Summer surface sensible heat flux is higher than climatological values in western China and lower in eastern China, while summer surface latent heat flux is higher than climatological values in the eastern and lower in the western. Seasonal variations of simulated temperature and precipitation of RIMES-AVIM agree with those of the observed. Simulated temperature is lower than the observed in the Tibetan Plateau and Northwest China for the whole year, slightly lower in the remaining regions in winter, but consistent with the observed in summer. The simulated temperature of RIEMS-AVIM is higher in winter and lower in summer than that of RIEMS, which shows that the simulated temperature of RIEMS-AVIM is closer to the observed value. Simulated precipitation is excessive in the first half of the year, but consistent with the observed in the second half of the year. The simulated summer precipitation of RIEMS-AVIM has significant improvement compared to that of RIEMS, which is less and closer to the observed value. The interannual variations of temperature and precipitation are also fairly well simulated, with temperature simulation being superior to precipitation simulation. The interannual variation of simulated temperature is significantly correlated with the observed in Northeast China, the Transition Region, South China, and the Tibetan Plateau, but the correlation between precipitation simu     

Latest Advances in Climate Change Detection Techniques

In recent years,the global warming and its influences on people and social economy have received increasing attention from international communities.Determining the current trend of global temperature variation has become one of the critical issues in climate change research.Obviously,it is rather important to develop new climate change detection technology in order to identify new characteristics of the global warming.This review introduces the latest advances and past achievements on the climate change...     

Characteristics of PM2.5 and Its Reactive Oxygen Species in Heating Energy Transition and Estimation of Its Impact on the Environment and Health in China——A Case Study in the Fenwei Plain

To reduce the adverse effects of traditional domestic solid fuel, the central government began implementing a clean heating policy in northern China in 2017. Clean coal is an alternative low-cost fuel for rural households at the present stage.In this study, 18 households that used lump coal, biomass, and clean coal as the main fuel were selected to evaluate the benefits of clean heating transformation in Tongchuan, an energy city in the Fenwei Plain, China. Both indoor and personal exposure(PE) ...     

Impact of the anomalous thawing in the Tibetan Plateau on summer precipitation in China and its mechanism

The impact of the anomalous thawing of frozen soil in the late spring on the summer precipitation in China and its possible mechanism are analyzed in the context of the frozen soil thawing date data of the 50 meteorological stations in the Tibetan Plateau, and the NCEP/NCAR monthly average reanalysis data.Results show that the thawing dates of the Tibetan Plateau gradually become earlier from 1980 to 1999,which is consistent with the trend of global warming in the 20th century. Because differences in the thermal capacity and conductivity between frozen and unfrozen soils are larger, changes in the freezing/thawing process of soil may change the physical properties of the underlying surface, thus affecting exchanges of sensible and latent heat between the ground surface and air. The thermal state change of the plateau ground surface must lead to the thermal anomalies of the atmosphere over and around the plateau, and then further to the anomalies of the general atmospheric circulation. A possible mechanism for the impact of the thawing of the plateau on summer (July) precipitation may be as follows. When the frozen soil thaws early (late) in the plateau, the thermal capacity of the ground surface is large (small), and the thermal conductivity is small (large), therefore, the thermal exchanges between the ground surface and the air are weak (strong). The small (large) ground surface sensible and latent heat fluxes lead to a weak (strong) South Asian high, a weak (strong) West Pacific subtropical high and a little to south (north) of its normal position. Correspondingly, the ascending motion is strengthened (weakened) and precipitationin creases (decreases) in South China, while in the middle and lower reaches of the Changjiang River, the ascending motion and precipitation show the opposite trend.     

Convective Scale Structure and Evolution of a Squall Line Observed by C-Band Dual Doppler Radar in an Arid Region of Northwestern China

A long-lived and loosely organized squall line moved rapidly across Urumqi, the capital city of Xinjiang Uygur Autonomous Region of China on 26 June 2005, generating hail and strong winds. The squall line was observed by a dual Doppler radar system in a field experiment conducted in 2004 and 2005 by the Chinese Academy of Meteorological Sciences and the local meteorological bureau in northwestern China. The 3D wind fields within the squall line were retrieved through dual Doppler analyses and a variational Doppler radar analysis system (VDRAS). The formation and structure of the squall line as well as the genesis and evolution of embedded convective cells were investigated. During its life period, the squall line consisted of six storm cells extending about 100 km in length, and produced hail of about 25 mm in diameter and strong surface winds up to 11 m s^-1. Radar observations revealed a broad region of stratiform rain in a meso-β cyclone, with the squall line located to the west of this. Two meso-γ scale vortices were found within the squall line. Compared to typical squall lines in moist regions, such as Guangdong Province and Shanghai, which tend to be around 300--400 km in length, have echo tops of 17--19 km, and produce maximum surface winds of about 25 m s^-1 and temperature variations of about 8^oC this squall line system had weaker maximum reflectivity (55 dBZ), a lower echo top (13 km) and smaller extension (about 100 km), relatively little stratiform rainfall preceding the convective line, and a similar moving speed and temperature variation at the surface.     

Kolmogorov Constants of Atmospheric Turbulence over a Homogeneous Surface

In this paper,the authors use ultrasonic data over a homogeneous surface to calculate the Kolmogorov constants of velocity,temperature,CO2,and water vapor.The authors find that the constants are all within the range determined by former experiments and that they are universally independent of the stability.