森林火风爆形成机制的研究

森林火风爆是一种飘移式风爆性大火灾,尽管以往已做过某些模拟试验,但未能触及到它的形成机制,对它所表现的某些外观特征也未能做出令人信服的解释,为此,本文对森林火风爆的形成机制进行了研究,现将结果介绍如下。一、森林火风爆的形成机制森林火风爆是由林火在某种外界因素影响下,由植物中的碳在空气中燃烧而形成的。 1、碳质可燃物的燃烧:森林可燃物是以碳为主的有机周体可燃物,它的燃烧是一个复杂的物理一一化学过程,是传质、传热、传动量的综合。

国外用水棚子隔绝煤尘爆炸

法国科学家塔法耐尔提出使用水棚子隔绝煤尘爆炸已有60多年历史了。不少国家对水棚子进行了大量的研究工作。目前水棚子已成为世界主要产煤国家广为使用的隔绝煤尘爆炸的措施之一。实践证明,正确而合理地在井下布置一些水棚子能隔绝某些煤尘爆炸。一、水棚子的隔爆原理和结构水棚子的隔爆原理很简单,在煤尘爆炸的传播路线安设一些装满水的容器,在爆风的作用下容器中水能在整个巷道断面上均匀地洒散开,扑灭爆炸火陷。

瓦斯煤尘爆炸试验巷道爆炸参量测试系统及其应用

本文介绍一套由计算机集中控制的快速多点分散检测设备,可测量爆炸压力,火焰速度、爆炸温度、爆风速度、冲击波速度等参量。

国外煤矿用自动隔爆棚子

为了克服被动式惰性岩粉棚子和水棚子的缺点,国外对自动隔爆棚子进行大量的研究工作。实践证明,自动隔爆棚子是一种行之有效的隔绝沼气和煤尘爆炸的措施之一。 1.自动隔爆棚子的优点 (1)自动隔爆棚子不依赖于煤尘和沼气爆炸所产生的爆风撒散灭火剂,可安设在潜在起爆点附近,如超前巷道、回采工作面、掘进工作面、爆源附近和狭窄低的巷道内; (2)自动隔爆棚子能准确地选择动作时间,瞬间可将灭火剂撒散到爆炸火焰锋面前方,有效地将爆炸火焰扑灭在萌芽状态中;

“中国信心”抗击金融风暴的思考

由美国次贷危机引发的金融危机,自其爆发以来,以人们难以想象的速度冲击着世界经济、政治以及人们的生活。很多人在这场金融灾难面前不知所措,恐慌的阴霾曾经笼罩着整个世界。面对金融风暴的袭击,中国政府和中国人民淡定自若、不屈不挠,以其特有的信心和勇气,通过卓有成效的努力,向世界展示了抗击金融风暴的坚定信心,并通过特有的"中国信心"影响了世界。

对冷冻尾气回收工艺的试验

油脂浸出厂的生产管理中,溶剂损耗是一项重要的经济技术指标,它不仅在生产成本中占有很大的比例,而且关系到工人的身体健康和安全生产.因此,降低浸出油厂的溶剂消耗是一项重要的课题.我们于一九八五年十月份在铁岭市油脂厂采用冷冻尾气回收溶剂工艺,并通过了三个多月的生产实践,于八六年一月份对该工艺的工艺参数进行了测试和鉴定.

立风井防爆门现状与发展

通过介绍B78型立风井防爆门结构和使用中存在的问题,阐述了新型防爆门的结构形式、设计原理、制造技术和使用情况,为今后立风井防爆门的设计选型提供有益借鉴。

煤矿用锚杆机液压系统冷却装置设计

锚杆机是煤矿井下掘进工作面巷道支护的主要设备,其行走、打钻和紧固锚杆机构以及除尘系统全部采用液压系统控制,由于煤矿井下掘进工作面作业环境恶劣,通风风量较小,加之锚杆机本身设计原因,运行过程中,锚杆机液压油经常出现高温,导致设备出现高温报警、停机,严重影响掘进巷道支护工作,从而影响掘进进度.本文设计在现有锚杆机液压系统回路中加装防爆风冷却器,降低锚杆机液压系统中液压油温度,确保锚杆机工作中液压油不出现高温故障,从而使锚杆机可以快速、安全、高效地完成支护工作,保障矿井掘进进度.

金融危机下房地产业态势分析

股市狂泻、油价爆跌,金融风爆袭卷全球;美国次贷经济危机泱及世界,不适经济政策,过度开发利用先进技术,严重的产能过剩,引发全球金融危机;中国经济遭创、产业受害、资本市场活跃、股市走红、不和谐明显,中央政府果断整合,快速回暖、初显曙光;金融温度计的房地产业,逆势而行,现象怪异,地价、房价红旗飘扬,房地产市场泡沫严重,3万元时代是否开启,高位房价走势何方?房价拐点何时出现,房产政策调整在急,没有宏观经济与政策面支撑,市场几乎饱和、居民购买力不足的房地产业路在何方?态势发展必将是房价稳中趋降,服从经济发展规律、服从市场价格规律,回归本来面貌。

Marine Atmospheric Boundary Layers Associated with Summer Monsoon Onset over the South China Sea in 1998

The variations of the marine atmospheric boundary layer (MABL) associated with the South China Sea Summer Monsoon were examined using the Global Positioning System (GPS) sounding datasets obtained four times daily during May-June 1998 on board Research Vessels Kexue 1 and Shiyan 3. The MABL height is defined as the height at the lowest level where virtual potential temperature increases by 1 K from the surface. The results indicate that the MABL height decreased over the northern South China Sea (SCS) and remained the same over the southern SCS, as sea surface temperature (SST) fell for the northern and rose for the southern SCS after the monsoon onset. Over the northern SCS, a decrease in both the SST and the surface latent-heat flux after the onset resulted in a reduction of the MABL height as well as a decoupling of MABL from clouds. It was found that MABL height reduction corresponded to rainfall occurrence. Over the southern SCS, a probable reason for the constant increase of SST and surface heat flux was the rainfall and internal atmospheric dynamics.

Thermal contrast between the Tibetan Plateau and tropical Indian Ocean and its relationship to the South Asian summer monsoon

The land-sea thermal contrast is an important driver for monsoon interannual variability and the monsoon onset.The thermal contrast between the Tibetan Plateau and the tropical Indian Ocean at the mid-upper troposphere is proposed as a thermal contrast index(TCI)for South Asian monsoon.The authors investigate the TCI associated with South Asian summer monsoon(SASM)intensity and SASM onset.It is observed that the TCI considering the Tibetan Plateau and tropical Indian Ocean demonstrates a stronger and closer correlation with SASM intensity(0.87)than either the Tibetan Plateau(0.42)or tropical Indian Ocean(-0.60)singly.It is implied that the TCI could preferably represent the impact of land-sea thermal condition on SASM activity.Further analysis reveals that the evolution of TCI is related to the SASM onset.The TCI is almost always larger in early onset years than it is in late onset years during the period before SASM onset.In addition,the change of the pentad-by-pentad increment of TCI leads the SASM variation.The correlation coefficient between the TCI increment and SASM index reaches a maximum when the TCI increment leads by 15 pentads.The results of this study show that the TCI plays an important role in SASM activities and is a potential indicator for SASM onset forecasting.

Temperature Inversion in the Bay of Bengal Prior to the Summer Monsoon Onsets in 2010 and 2011

Freshwater input such as runoff and rainfall can enhance stratification in the Bay of Bengal(BOB) through the formation of a "barrier layer",which can lead to the formation of a temperature inversion.The authors focused on the temperature inversion in spring,especially before the onset of the summer monsoon,because previous research has mainly focused on the temperature inversion in winter.Using the hydrographic data from two cruises performed during 24-30 April 2010 and 1-4 May 2011,the authors found that inversions appeared at two out of nine Conductivity-Temperature-Depth Recorder(CTD) stations across the 10°N section and at seven out of 13 CTD stations across the 6°N section in the BOB.In 2010,the inversions(at stations N02 and N05) occurred at depths of approximately 50-60 meters,and their formation was caused by the advection of cold water over warm water.In 2010,the N02 inversion was mainly influenced by the warm saline water from the east sinking below the cold freshwater from the west,while the N05 inversion was affected by the warm saline water from its west sinking below the cold freshwater from its east.In 2011,the inversions appeared at depths of 20-40 meters(at stations S01,S02,S07,S08,and S09) and near 50 m(S12 and S13).The inversions in 2011 were mainly caused by the net heat loss of the ocean along the 6°N section.

Low-Frequency Vortex Pair over the Tropical Eastern Indian Ocean and the South China Sea Summer Monsoon Onset

In this paper,the relationship between a pair of low-frequency vortexes over the equatorial Indian Ocean and the South China Sea(SCS) summer monsoon onset is studied based on a multi-year(1980-2003) analysis.A pair of vortexes symmetric about the equator is an important feature prior to the SCS summer monsoon onset.A composite analysis shows that the life cycle of the pair of vortexes is closely associated with the SCS summer monsoon onset.The westerly between the twin cyclones is an important factor to the SCS summer monsoon onset process.

Comparison of remote sensing data with in-situ wind observation during the development of the South China Sea monsoon

Wind measurements derived from QuikSCAT data were compared with those measured by anemometer on Yongxing Island in the South China Sea (SCS) for the period from April 2008 to November 2009. The comparison confirms that QuikSCAT estimates of wind speed and direction are generally accurate, except for the extremes of high wind speeds (>13.8m/s) and very low wind speeds (<1.5m/s) where direction is poorly predicted. In-situ observations show that the summer monsoon in the northern SCS starts between May 6 and June 1. From March 13, 2010 to August 31, 2010, comparisons of sea surface temperature (SST) and rainfall from AMSR-E with data from a buoy located at Xisha Islands, as well as wind measurements derived from ASCAT and observations from an automatic weather station show that QuikSCAT, ASCAT and AMSR-E data are good enough for research. It is feasible to optimize the usage of remote-sensing data if validated with in-situ measurements. Remarkable changes were observed in wind, barometric pressure, humidity, outgoing longwave radiation (OLR), air temperature, rainfall and SST during the monsoon onset. The eastward shift of western Pacific subtropical high and the southward movement of continental cold front preceded the monsoon onset in SCS. The starting dates of SCS summer monsoon indicated that the southwest monsoon starts in the Indochinese Peninsula and forms an eastward zonal belt, and then the belt bifurcates in the SCS, with one part moving northeastward into the tropical western North Pacific, and another southward into western Kalimantan. This largely determined the pattern of the SCS summer monsoon. Wavelet analysis of zonal wind and OLR at Xisha showed that intra-seasonal variability played an important role in the summer. This work improves the accuracy of the amplitude of intra-seasonal and synoptic variation obtained from remote-sensed data.

Variation of Air-Sea Heat Fluxes over the Western Pacific Warm Pool Area and Its Relationship with the South China Sea Summer Monsoon Onset

Based on oceanic and atmospheric parameters retrieved by satellite remote sensing using a neural network method, air-sea heat fluxes over the western Pacific warm pool area were calculated with the advanced the advanced Coupled Ocean-Atmosphere Response Experiment 3.0 (COARE3.0) bulk algorithm method. Then, the average annual and interannual characteristics of these fluxes were analyzed. The rela- tionship between the fluxes and the South China Sea (SCS) summer monsoon onset is highlighted. The results indicate that these fluxes have clear temporal and spatial characteristics. The sensible heat flux is at its maximum in the Kuroshio area, while the latent heat flux is at its maximum in the North Equatorial Current and Kuroshio area. The distribution of average annual air-sea heat fluxes shows that both sensible and latent heat fluxes are maximized in winter and minimized in summer. The air-sea heat fluxes have obvious interannual variations. Correlation analysis indicates a close lag-correlation between air-sea heat fluxes in the western Pacific warm pool area and at the SCS summer monsoon onset. The lagcorrelation can therefore predict the SCS summer monsoon onset, providing a reference for the study of precipitation related to the monsoon.

An Analysis of the Characteristics of Monsoon Onset over the Bay of Bengal and the South China Sea in 2010

Based on NCEP/NCAR daily reanalysis and the Tropical Rainfall Measuring Mission data, the back- ground atmospheric circulation and the characteristics of meteorological elements during the period of the Bay of Bengal monsoon （BOBM） and the South China Sea （SCS） monsoon （SCSM） in 2010 are studied. The impacts of the BOBM onset on the SCSM onset and the relationship between the two monsoons are also analyzed. The two main results are as follows： （l） The BOBM onset obvi- ously occurs earlier than the SCSM onset in 2010, which is a typical onset process of the Asian monsoon. During the BOBM＇s onset, northward jump, and eastward expansion, convective precipitation and southwest winds occurred over the SCS, which resulted in the onset of the SCSM. （2） The relationship among strong convection, heavy rainfall, and vertical circulation configuration is obtained during the monsoon onsets over the BOB and SCS, and it is concluded that the South Asian High plays an important role in this period.

Influence of Tropical Western Pacific Warm Pool Thermal State on the Interdecadal Change of the Onset of the South China Sea Summer Monsoon in the Late-1990s

An interdecadal shift in the onset date of the South China Sea summer monsoon(SCSSM) is identified during the late 1990 s by using the European Centre for Medium-Range Weather Forecasts Interim Reanalysis dataset. The mean onset date was brought forward by two pentads during 1999–2013 compared to that during 1979–1998. The large-scale atmospheric and oceanic change associated with this shift exhibits a significant interdecadal variation signal around 1998/1999, indicating that the shift during the late 1990 s is robust. Different from the well-known mid-1990 s shift, this shift carried more important systematical significance. Diagnostic analysis suggests that the earlier outbreak of the SCSSM was due to the interdecadal warming of the warm pool, which brought stronger convection anomalies and led to a weak western Pacific subtropical high(WPSH) during boreal spring(March–May). The earlier retreat of the WPSH was a direct cause of this shift.

Energetics characteristics accounting for the low-level wind’s rapid enhancement associated with an extreme explosive extratropical cyclone over the western North Pacific Ocean

During mid-January 2011,a rarely seen twin-extratropical-cyclone event appeared over the western North Pacific Ocean.One of the twin cyclones developed into an extreme explosive extratropical cyclone(EEC),which was comparable to the intensity of a typhoon.Rotational and divergent wind kinetic energy(KE)analyses were applied to understand the low-level wind’s rapid enhancement associated with the cyclone.It was found that:(i)the total wind KE associated with the EEC showed a remarkable enhancement in the lower troposphere during the cyclone’s maximum development stage,with the maximum/minimum wind acceleration appearing in the southeastern/northwestern quadrant of the EEC;(ii)the rotational wind KE experienced an obvious increase,which corresponded to the total wind KE enhancement,whereas the divergent wind KE,which was much smaller than the rotational wind,mainly featured a decreasing trend;(iii)the rotational wind KE enhancement showed variational features consistent with the horizontal enlargement and upward stretching of the EEC;(iv)the nonorthogonal wind KE enhanced the total wind KE in regions with strong rotational wind,which resulted in the maximum lower-tropospheric maximum wind,whereas in regions with strong divergent wind it mainly reduced the total wind KE;(v)the northward transport of total wind KE and the rotational wind KE production due to the work done by pressure gradient force were dominant factors for the enhancement of winds associated with the EEC,particularly in its southeastern section.In contrast,an overall conversion from rotational wind KE to divergent wind KE decelerated the rotational wind enhancement.

Definition of the South China Sea summer monsoon onset

We analyze statistically different definitions of the South China Sea summer monsoon(SCSSM) onset are to establish a SCSSM onset time series that is more recognizable by a majority of indicators.With the acknowledged index,we determine a key area(105°E-112.5°E,7.5°N-12.5°N) and define the zonal wind component in this key area as a new SCSSM onset index,using daily mean reanalysis data of the National Center for Environmental Prediction/National Center for Atmospheric Research.The atmospheric circulations before and after the onset of the SCSSM determined using the index defined in this paper are preliminarily studied.Results show that the Somalia cross-equatorial flow is enhanced,the strongest westerly wind in the tropical Indian Ocean shifts northward,the cyclone couple in the Bay of Bengal and the Southern Hemisphere weaken and move eastward,convection over the South China Sea increases,and the subtropical high retreats from the South China Sea after the outbreak of the SCSSM.By analyzing the atmospheric circulation,it is found that in 1984 and 1999,the SCSSM broke out in pentads 29 and 23,respectively,which is consistent with the onset times determined using our index.

COMPARISON OF CHARACTERISTICS BETWEEN THE SOUTH CHINA SEA SUMMER MONSOON OUTBREAKS IN 2004 AND 2008

The South China Sea summer monsoon is an important system affecting the weather and climate in China;its outbreak and evolution vary from year to year.Using the reanalysis data from the U.S.National Centers for Environmental Prediction (NCEP) and outgoing longwave radiation (OLR) data from the National Oceanic and Atmospheric Administration (NOAA),USA,we analyze the circulation pattern,precipitation distribution,convection,temperature,and humidity around the monsoon outbreaks in 2004 and 2008.Results show that the monsoon had a late onset in 2004 (May 19) but an early outbreak in 2008 (May 4).Prior to the monsoon outbreak in 2008,cross-equatorial flows in Somalia were weaker than in 2004,subtropical precipitation did not arrive in southern China as it did in 2004,and the strongest convection was located more southward than in 2004.The results also indicate that accumulated rainfall in the Indochina Peninsula was about 61% of that in 2004 during a period of 25 days leading up to the monsoon outbreak,causing differences in land surface processes and then different activity levels for the summer monsoon.Post-onset warm and humid conditions in 2008 (2004) maintained through the end of October (mid-September),while the summer monsoon lasted longer in 2008 than in 2004.