Formation Reason Analysis and Defense Countermeasure of Rare Frozen Disaster in Guizhou in 2008

[Objective] The research aimed to discuss the formation reason of low temperature and frozen disaster weather event in Guizhou in 2008.[Method] By using T213,ECMWF numerical forecast data and the conventional meteorological observation data which were provided by MICAPS,according to the variation situations of frozen rain,freezing,road freezing and ground surface 0 ℃ line range,the weather situation evolution characteristic of low temperature and frozen weather process (congelation for short) in Guizhou from January 13 to February 15,2008 was analyzed.The formation reason of low temperature and frozen disaster weather event in Guizhou was discussed,and the defense countermeasure was put forward.[Result] The low temperature and frozen weather process happened when the continuous precipitation was caused by that every scale weather system intersected in Guizhou under the abnormal atmospheric circulation background.East Asian inverted Ω flow type in the northern hemisphere made that the atmospheric circulation stabilized for a long time,and the north branch frontal zone was by south.The polar cold air continued to complement and went south to affect Jiangnan,South China.The south branch westerly fluctuation was active,and the frontal zone intensity of stationary front was big,which maintained for a long time.850 hPa shear line in the low level maintained to swing in the junction of Guangxi and Guizhou,Hunan.The southwest warm and wet airflow continued transporting to the south of China.The cold and warm air intersected in South China,which caused the long-time precipitation in Guizhou.The thermal inversion layer was deep and thick.The long-time precipitation based generally on the light rain.It was easy to form the supercooled water droplet.The verglas range expanded from Guizhou,the south of Hunan to the north of Guangxi.The frozen rain and frozen weather caused the long-time road and wire freezing.The disaster was serious.The ground surface temperature 0 ℃ line covered the cold mountain area in the whole province for a long time.The ground surface freezing was difficult to melt,and the low temperature and frozen weather affected Guizhou for a long time.[Conclusion] The research accumulated the experience for the disaster prevention and reduction of such weather.

Analysis on the Influence of Spring Low Temperature on the Agriculture and the Formation Reason in Liaoning Province in 2010

[Objective] The research aimed to study the influence of spring low temperature on the agriculture and the formation reason in Liaoning Province in 2010. [Method] Based on the synoptics analysis principle, by analyzing the atmospheric circulation situation and satellite cloud map, the influence of spring low temperature on the agriculture and the formation reason of low temperature weather in Liaoning Province during April-May, 2010 were discussed. [Result] The high-altitude situation analysis showed that it was two-trough-two-ridge situation in the high latitude of Eurasia in April, 2010. Ural Mountains high-pressure ridge strengthened to move eastward. Lake Baikal cold air went down toward the southeast along the front of ridge and strengthened into the cold vortex. Liaoning was in the front of cold vortex. Affected by the cold vortex, the temperature in Liaoning area was low. In the first dekad of May, 2010, the activity of cold air was frequent. There were two times cold vortex influence, and the temperature was still low. In the later period of middle dekad of May, the warm ridge entered, and the temperature rose. The high-altitude trough and the low-level jet were the main system and the dynamic condition of precipitation generation respectively. The cold vortex was the main reason of spring continuous low temperature generation, and the secondary reason was the more precipitation. [Conclusion] The research provided the reference basis for the prevention and prediction of spring low temperature in Liaoning Province.

Analysis on Formation Reason of a Local Heavy Rainstorm in Linyi Area

[Objective] The research aimed to study formation reason of a local heavy rainstorm process in Linyi from night on August 3 to early morning on 4th, 2010. [Method] Based on MICAPS weather chart, actual situation data of NECP analysis field, data of automatic encryption station and Doppler radar product, a local heavy rainstorm and extra heavy rainstorm process in Linyi from night on August 3 to early morning on 4th, 2010 was detailedly analyzed from weather background, meso- and micro-scale characteristics, physical mechanisms of occurrences and developments of meso and micro-scale systems. The formation reason of heavy rainstorm process was discussed. Moreover, we tried to find some occurrence rules of short-time strong precipitation. [Result] The local heavy rainstorm process had large short-time rainfall and obvious local characteristics. The main influence systems were subtropical high, westerly trough, meso- and small-scale ground low pressures. It was affected by many systems which had different scales and heights. The up-cold-down-warm unstable stratification accumulated a large number of unstable energy, which was basic condition of strong precipitation occurrence. It was convergence shear line at the bottom layer of airspace. The vertical shear and turbosphere of deep southwest-northwest-easterly airflow were at airspace. The common effect of up and down systems triggered generation of updraft, and made unstable energy release. For the release of unstable energy, after northwest airflow was cut off, the updraft made southwest airflow develop upward. It linked with easterly wave to form new vertical shear, which was a reason of long duration of strong precipitation. The southwest airflow at the edge of subtropical high was water vapor source of precipitation process, which provided sufficient water vapor supply for generation of heavy rainstorm. The system which was developing and strengthening would make the moving speed of system slow down. Then, the rainfall increased. It was a reason of long duration of strong precipitation. [Conclusion] The research accumulated certain experience for forecast work in future.

Analysis on Formation Reason of "0902" Blizzard in Northeast China

[Objective]The research aimed to analyze formation reason of ＂ 0902＂ blizzard in northeast China. [Method]By using timely observation data,NCEP reanalysis data and Doppler radar data at Baishan station,blizzard process in southeast part of northeast China during 12-13 February,2009 was analyzed. [Result]Snowfall zone of the blizzard process was wide,snowfall was more,snowfall gradient was big,and snowfall time relatively concentrated. These characteristics reflected that the blizzard process had significant convection characteristics. Baroclinic disturbance at high-altitude straight frontal zone and ground warm frontogenesis caused by eastward movement and northward advancement of North China low vortex at low altitude were the circulation characteristics in the process. Water vapor from the sea went northward as southwest airflow,and strongly converged in blizzard zone,which provided sufficient water vapor condition for the blizzard. Before heavy snowfall occurred,there was accumulation process of heat and energy. Conditional symmetric instability was main unstable mechanism of the blizzard. During heavy snowfall period,ascending branch of secondary vertical circulation at exit zone of high-altitude jet coupled with ascending branch of secondary vertical circulation of warm frontegenesis at low layer,inducing strong development of the vertical motion. Doppler radar intensity echo revealed that it was easy to generate blizzard in the area where echo intensity was consistently above 20 dBz. Strong wind velocity convergence zone at radical velocity field especially adverse wind zone was favorable for the generation of blizzard. [Conclusion]The research could provide reference for blizzard forecast in northeast China.

An analysis on the formation mechanism of the distributionof high content of chlorophyll-a in the continentalshelf edge waters of East China Sea

On the basis of the data obtained from the comprehensive Kuroshio surveys in 1987-1988,this paper analyses the oceanographic characteristics in the area (125°-130° E,27°-31° N) of the continental shelf edge of the East China Sea (E. C. S. ) and its adjacent waters and discusses the effects of the Kuroshio front,thermocline and upwelling of the Kuroshio subsurface water on the distribution of standing stock of phytoplankton (chlorophyll-a). The distribution of high content of chlorophylly-a has been detected at 20-50 in depth in the water body on the left side of the Kuroshio front in the continental shelf edge waters of the E. C. S. The high content of chlorophyll-a spreads from the shelf area to the Kuroshio area in the form of a tongue and connects with the maximum layer of subsurface chlorophyll-a of the Kuroshio and pelagic sea. The author considers that the formation of the distribution of high content chlorophyll-a in this area results from the bottom topography and oceanic environment and there are close correlations between the high content of chlorophyll-a and the light-nutrient environment.

Stability analysis and determination of rock pillar between two adjacent caverns in different regions of Asmari formation in Iran

Large underground caverns are commonly used in variety of applications. In many cases, because of the geomechanical limitations of dimensions and requirement of high volume, several parallel caverns are used. Plastic zone integration requires a larger rock pillar distance of theses adjacent caverns while eco- nomic and access reasons require smaller distance. In lran many underground projects are located in West and South West, Asmari formation covers a large part of these regions. The stability of underground spaces that are constructed or will be constructed in this formation has been investigated. A proper cross section based on plastic analysis and a stability criterion has been proposed for each region. Finally, in each case, allowable rock pillar between adjacent caverns with similar dimension was determined with two methods （numerical analysis and fire service law）. Results show that Fire Service Law uses a very con- servative safety factor and it was proposed to use a correction factor for allowable distance based on application of underground space.

A study on Holocene aeolian shell-clastic sandstonesalong the coasts of South China andthe analysis of its formation

The Holocene aeolian shell-clastic sandstones at 13 places along the coasts of Fujian, Guangdong and Hainan Provinces are studied in the following respects; describing their features from both macroscopic and microscopic views, listing their distributions, altitudes and forming ages, and discussing the nomenclatures of this kind of rock and its differences from beach rock.

Behavioural analysis and dynamic simulation of the debris flow that occurred in Ganluo County(Sichuan, China) on 30 August 2020

On August 30, 2020, a high-intensity storm that dropped 45.4 mm of rain in 5 hours hit the Heixiluo basin and triggered a landslide-generated debris flow event, causing fatalities and damage. The original source of the debris flow was a large slope collapse on a steep hillside. The fallen debris mass was enlarged through sediment entrainment and slope collapse and ultimately buried a bridge at the gully entrance. Approximately 6.9×10;m;of material, including sediments and collapsed slope deposits in the gullies, was entrained, and the maximum erosion depth reached 17 m. A geomorphological analysis was initially performed based on a detailed field investigation to recognize the liquid and solid sources of the debris flow and the areas subjected to deposition and erosion. A map of the erosiondeposition distribution was obtained based on preand post-event DEMs. Using the rainfall estimated by the nearest rain gauge and the solid source estimated by the DEMs, runoff and debris flow propagation was simulated using a liquid-solid two-phase model that considers the effects of runoff and entrainment. The similarity between the estimated and simulated deposition-erosion volumes was satisfactory. The behaviour of debris flows captured in the simulation is broadly in line with the main features of the observed event.

A back-propagation neural-network-based displacement back analysis for the identification of the geomechanical parameters of the Yonglang landslide in China

Xigeda formation is a type of hundredmeter-thick lacustrine sediments of being prone to triggering landslides along the trunk channel and tributaries of the upper Yangtze River in China. The Yonglang landslide located near Yonglang Town of Dechang County in Sichuan Province of China, which was a typical Xigeda formation landslide, was stabilized by anti-slide piles. Loading tests on a loading-test pile were conducted to measure the displacements and moments. The uncertainty of the tested geomechanical parameters of the Yonglang landslide over certain ranges would be problematic during the evaluation of the landslide. Thus, uniform design was introduced in the experimental design,and by which, numerical analyses of the loading-test pile were performed using Fast Lagrangian Analysis of Continua(FLAC3D) to acquire a database of the geomechanical parameters of the Yonglang landslide and the corresponding displacements of the loadingtest pile. A three-layer back-propagation neural network was established and trained with the database, and then tested and verified for its accuracy and reliability in numerical simulations. Displacement back analysis was conducted by substituting the displacements of the loading-test pile to the well-trained three-layer back-propagation neural network so as to identify the geomechanical parameters of the Yonglang landslide. The neuralnetwork-based displacement back analysis method with the proposed methodology is verified to be accurate and reliable for the identification of the uncertain geomechanical parameters of landslides.

Analysis on the Disastrous Weather of Serious Drought in Northwest Hunan in Summer and Autumn of 2009

[Objective] The research aimed to analyze the disastrous weather of serious drought in Northwest Hunan in summer and autumn of 2009.[Method] According to the meteorological data in Zhangjiajie of Northwest Hunan during the drought period from June to September,2009,the disaster characteristics of continuous drought in summer and autumn were analyzed.Based on NCEP/NCAR 2.5°×2.5° reanalysis data,by using the climatic diagnostic method,the formation reason of serious drought was initially analyzed from the circulation characteristics in the middle and high latitudes,Western Pacific subtropical high,the abnormal characteristics of sea surface temperature in the equatorial Middle Eastern Pacific Ocean and the tropical system activity.[Result] The characteristics of serious drought in Northwest Hunan in summer and autumn of 2009 were the quick developed speed,wide influence range,long duration,big disaster loss and long high temperature time.The influence range,duration and harm degree were rare to see in the history.During the arid period(June-September),the atmospheric circulation was abnormal.The polar vortex in the northern hemisphere was weak,and the center was by north.It was two-trough-one-ridge type in the middle and high latitudes of Eurasia.The long-wave trough existed respectively near Balkhash Lake and from Sea of Okhotsk to the east coast in China.The long-wave ridge maintained from Lake Baikal to Central Asia and stabilized in 90°-110° E of Central Asia.From the middle dekad of June to the middle dekad of September,the westerly index increased.The zonal circulation was the main one in the middle and high latitudes of Eurasia.The cold air in the high-latitude frontal zone spread eastward with the small-amplitude fluctuation form along the latitude circle direction,and was difficult to pass the westerly barrier near 45° N to reach the low latitude.Meanwhile,Western Pacific subtropical high jumped northward to control Jiangnan and South China for a long time.The down airflow was prevalent.It was hot and rainless.The drought developed quickly.The sea surface temperature in the equatorial Middle Eastern Pacific Ocean started to rise in June,and it entered into El Nino state.When El Nino event of obvious temperature increasing started to appear in spring and summer,the plum rain amount was less in the middle and low reaches of Yangtze River in the year or next year.The probability was 80%.In El Nino year,the typhoon was less.In addition,for the influence of strong Western Pacific subtropical high,the landing pathway of typhoon was by east or south.The kind of typhoon had the small role for easing the drought in Northwest Hunan.[Conclusion] The research provided the theory basis for improving the prediction level of short-term climate and the understanding of extreme climate event.

Sedimentology,provenance and geochronology of the Miocene Qiuwu Formation:Implication for the uplift history of Southern Tibet

Located on the south of the Gangdese,the Qiuwu Formation has traditionally been considered as Eocene coal-bearing clastic sediments consisting of sandstone,mudstone and conglomerate,unconformably on top of Gangdese batholith.However,its precise age and depositional environment remain ambiguous.Here,we present a newly measured stratigraphic section near the Ngamring County,western Xigaze.Detrital zircon U-Pb ages were also applied to trace the provenance of sediments and to constrain the maximum depositional age of the Qiuwu Formation.Sedimentary facies analyses indicate subaqueous fan and alluvial fan depositional environments.Clast composition of the conglomerate is dominated by magmatic rocks at the lower part,while chert and mafic detritus occur in the upper part,suggesting a southern source.Sandstone modal analyses indicate that the compositions of quartz,feldspar and lithic grains changed from transitional arc to dissected arc,implying the unroofing of the Gangdese arc.Detrital zircon U-Pb ages of the Qiuwu Formation are compared with those from Gangdese magmatic rocks and Yarlung-Zangbo ophiolites,suggesting that the Gangdese arc is a main source of the Qiuwu detritus and that the southern source played a role during the later stage.The major peak of detrital zircon ages is at 45-55 Ma,which corresponds to Linzizong volcanic rocks in southern Gangdese arc.The weighted mean age of the five youngest zircons from the lower part of the section is 21.0 ± 2.2 Ma,suggesting that the Qiuwu Formation was deposited in early Miocene,coeval with other conglomerates exposed along the southern margin of Gangdese.Combining new observations with previously published data,we propose that the provenance of the Qiuwu Formation had shifted from a single northern source to double sources from both the north and the south.Activities of Great Counter Thrust were primarily responsible for the shift by making the south area a high elevation to provide sediments for the Qiuwu Formation.

Experimental study on the degree and damage-control mechanisms of fuzzy-ball-induced damage in single and multi-layer commingled tight reservoirs

Fuzzy-ball working fluids(FBWFs)have been successfully applied in different development phases of tight reservoirs.Field reports revealed that FBWFs satisfactorily met all the operational and reservoir damage control requirements during their application.However,the damage-control mechanisms and degree of formation damage caused by fuzzy-ball fluids have not been investigated in lab-scale studies so far.In this study,the degree of fuzzy-ball-induced damage in single-and double-layer reservoirs was evaluated through core flooding experiments that were based on permeability and flow rate indexes.Additionally,its damage mechanisms were observed via scanning electron microscope and energy-dispersive spectroscopy tests.The results show that:(1)For single-layer reservoirs,the FBWF induced weak damage on coals and medium-to-weak damage on sandstones,and the difference of the damage in permeability or flow rate index on coals and sandstones is below 1%.Moreover,the minimum permeability recovery rate was above 66%.(2)For double-layer commingled reservoirs,the flow rate index revealed weak damage and the overall damage in double-layer was lower than the single-layer reservoirs.(3)There is no significant alteration in the microscopic structure of fuzzy-ball saturated cores with no evidence of fines migration.The dissolution of lead and sulfur occurred in coal samples,while tellurium in sandstone,aluminum,and magnesium in carbonate.However,the precipitation of aluminum,magnesium,and sodium occurred in sandstone but no precipitates found in coal and carbonate.The temporal plugging and dispersion characteristics of the FBWFs enable the generation of reservoir protection layers that will minimize formation damage due to solid and fluid invasion.

Mass segregation of embedded clusters in the Milky Way

Embedded clusters are ideal laboratories for understanding the early phase of the dynamical evolution of clusters as well as massive star formation. An interesting observational phenomenon is that some of the embedded clusters show mass segregation, i.e., the most massive stars are preferentially found near the cluster center. We develop a new approach to describe mass segregation. Using this approach and the Two Micron All Sky Survey Point Source Catalog （2MASS PSC）, we analyze 18 embedded clusters in the Galaxy. We find that 11 of them are mass-segregated and that the others are not mass-segregated. No inversely mass-segregated cluster is found.

Phenyl iodonium bis(perfluoroalkanesulphonyl)-methide-dimethyl sulphoxide complex——Its formation and X-ray structure analysis

Irradiation of phenyl iodonium bis(perfluoroalkanesulphonyl)methide in DMSO yields an 1:1 adduct, DMSO·PhI=C(SO_2R_F)_2 (2) which was confirmed by X-ray crystal structure analysis.

Power distribution analysis for multiple modulation formats in an all-optical sampling wavelength division multiplexing system

An optimal power distribution analysis for an all-optical sampling orthagonal frequency division multiplexing(OFDM) scheme with multiple modulation formats including diferential phase shift keyed(DPSK), diferential quadrature phase shift keyed(DQPSK), and non-return-to-zero(NRZ) is proposed. The noise tolerances of different modulation formats are analyzed, and the optimal input power ratio between phase and intensity modulation formats for the best overall receiving performance is investigated under unchanged total input power. Moreover, this scheme can seamlessly coexist with the traditional WDM channel.

A dynamic two-zone model of continuous fluidized bed layering granulation with internal product classification

A dynamic two-zone model is proposed to address the formation of granulation and drying zones in fluidized bed layering granulation processes with internal product classification. The model assumes a constant volume for the granulation zone, but a variable overall volume for the fluidized bed to account for classified product removal. The model is used to study the effect of various process parameters on dynamics and process stability. Stability is shown to depend on the separation diameter of product removal and the flow rate of the injected liquid. A lower and upper range of separation diameters with stable process behavior are found. In an intermediate range instability in the form of self-sustained oscillations is observed. The lower stability boundary is in qualitative agreement with recent experimental observations （Schmidt, Bück, ＆ Tsotsas, 2015）; the upper boundary was reported in a theoretical paper by Vreman, Van Lare, and Hounslow （2009） based on a single zone model.