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781.
陈伟 《安全.健康和环境》2003,3(7):34-36
本文运用美国道化学公司危险指数评价法对MIBE装置进行定量化的安全评价,说明装置建成后,其固有的危险便客观存在,由于设计时采用了一些安全措施,起到了安全补偿作用,使实际的危险程度达到可接受的范围;同时通过评价,识别导致事故的危险因素,完善安全措施,可以进一步降低装置的风险度。 相似文献
782.
土壤水分对沙尘暴的阈值反应--以内蒙古中西部地区为例 总被引:6,自引:3,他引:6
以2001年4月至2003年6月内蒙古中西部地区逐时观测的土壤体积含水百分率资料为基础,论述了土壤体积含水百分率的时间变化规律及其对沙尘暴的阈值反应.得到的主要结论是:(1)土壤体积含水百分率有着单峰型日波动反应,最高和最低值分别出现在午后4时和午前9时.(2)土壤体积含水百分率的月际变化基本遵循以1a为周期作简单振动的变化规律,最低值出现在3~4月.土壤体积含水百分率全年波动介于18.5%~37.3%之间,年平均值为26.5%.(3)沙尘暴的发生在土壤体积含水百分率含量一定范围内并不随土壤含水量的降低而发生明显变化,但当土壤体积含水百分率低于19.5%时,则随着土壤体积含水百分率的降低而明显增加,表现为土壤体积含水百分率有明显的阈值反应.(4)引进沙尘暴时度的概念研究了沙尘暴发生的持续时间,由沙尘暴时度与土壤体积含水百分率的指数关系发现,在时度大于200min和小于120min的两类沙尘暴中,土壤体积含水百分率每降低1%,沙尘暴时度将分别增加19.94min和10.14min. 相似文献
783.
784.
地下储罐爆炸事故源强估算 总被引:1,自引:0,他引:1
从能量释放的角度出发,以爆炸理论为基础,利用爆破技术中已得出的结论,着重研究地下储罐爆炸事故源强的估算方法。确定各种伤害效应的安全距离,为预防事故和安全评价提供理论依据。 相似文献
785.
The Influence of Synoptic-scale Air Flow and Local Circulation on the Dust Layer Height in the North of the Taklimakan Desert 总被引:1,自引:0,他引:1
Nobumitsu Tsunematsu Kenji Kai Takuya Matsumoto 《Water, Air, & Soil Pollution: Focus》2005,5(3-6):175-193
The present study investigates the influences of synoptic-scale air flows and local wind circulations on the dust layer height
(DLH) in the Taklimakan Desert, based on lidar observations performed in the north of the desert in March 2003. The DLH fluctuates
approximately every three days between 2500 m (above sea level) and 5000 m, including diurnal variations. Meteorological analyses
and numerical simulations show that the three-day fluctuation of DLH corresponds with variations in synoptic-scale air flows
over the Taklimakan Desert, and the diurnal variations are linked to downdrafts and updrafts that are formed over the north
of the desert as part of local circulations. When strong northerly winds prevail in the upper troposphere and a developed
valley wind blows toward the Tienshan Mountains in the lower troposphere, the downdrafts strengthen in the middle troposphere
over the north of the desert, lowering the DLH to about 2500 m. In contrast, the DLH rises to about 5000 m when the updrafts
develop between strong southerly winds in the upper troposphere and a developed mountain wind blowing from the Tienshan Mountains.
Simulations for the local circulation behavior without the presence of the Tienshan Mountains demonstrate that the valley
and mountain winds on the southern slope of the Tienshan Mountains control the intensity of the downdrafts and updrafts, thereby
influencing the DLH over the north of the Taklimakan Desert. 相似文献
786.
Daizhou Zhang Guangyu Shi Yasunobu Iwasaka Min Hu Jiaye Zang 《Water, Air, & Soil Pollution: Focus》2005,5(3-6):261-276
Analysis of individual particles collected at Beijing in northern China revealed that particles abundant in calcium (Ca) always
constituted a large fraction of mineral particles in the urban atmosphere. The particles were characterized by cubic morphologies.
The major mineral element in the particles was Ca and few or no other mineral elements were detected. A large number of the
particles were in the range of diameter <1 μm, where common natural mineral particles were rarely detected. The contribution
of the Ca particles to the volume of total mineral particles greatly exceeded that of other mineral particles during non-dust-storm
periods and was comparable to that during dust-storm periods. Reagent film tests showed that particulate sulfate and nitrate
formation on the Ca particles was similar to that on common mineral particles. These results indicate that a large portion
of Ca in the atmospheric particulate matter in Beijing was from anthropogenic sources rather than from natural sources, and
the anthropogenic Ca particles acted as a significant medium for the formation of sulfate and nitrate. Similar particles were
also detected at Qingdao, a coastal city in northern China. Data of a dust storm event showed that Ca-abundant particles from
East China arrived there and moved out of the continent, similarly to Asian dust storm particles, suggesting possible contributions
of anthropogenic Ca even in Asian dust storm samples in the downstream areas. Therefore, Ca may not be a good indicator of
Asian dust from natural sources. However, the Ca particles, due to their unique shapes and elemental compositions, may provide
an indicator for the atmospheric dispersion of anthropogenic particulate matters in East Asia. 相似文献
787.
Wenshou Wei Hongfei Zhou Yuguang Shi Osamu Abe Kenji Kai 《Water, Air, & Soil Pollution: Focus》2005,5(3-6):207-216
The desert environmental changes in the source areas of dust storms occurring in Xinjiang are discussed based on the climate
changes and the impacts of human activities in Xinjiang during the past 50 years. The results show that the climate in Xinjiang
is changing from a warm-dry type to a warm-wet one. The warm-wet climate has been obvious since the mid-1970's, and especially
the sensitivity of the regional climate change in this arid area is obviously revealed by many factors, such as the characteristics
of the local climate change in south Xinjiang and north Xinjiang, the difference of climate change in the alpine zones and
the basins, and the change of areas of the waters bodies. Furthermore, these factors also reveal the difference in the regional
climate change between Xinjiang and central and eastern areas of China. The occurrence and development of dust storms are
directly affected by the precipitation, air humidity, status of underlying surface, etc. in the arid areas. The frequency
and intensity of dust storms are closely related to the natural conditions, changes of climate and desert environment, as
well as the dynamic conditions (i.e., weather systems) in the source areas of dust storms. Therefore, global warming is one
of the main causes resulting in the degradation of the ecological environment and the frequent occurrence of natural disasters,
especially the disasters of sand drift and dust storms in the arid areas since the late-1980's, which reveals that the inland
arid areas are sensitive regions to climate changes. 相似文献
788.
Airborne particulate matter (PM) concentrations were measured in Iksan, a suburban area in South Korea during April, 2003.
PM2.5 (particles with an aerodynamic diameter less than 2.5 μm) and PM10 (particles with an aerodynamic diameter less than 10 μm) samples were collected, and the chemical characteristics of particles
were examined for diurnal patterns, yellow dust/rainfall influences, and scavenging effects. Average concentrations of PM2.5 and PM10 mass measured were 37.3 ± 16.2 μg m−3 and 60.8 ± 29.5 μg m−3, respectively. The sum of ionic chemical species concentrations for PM2.5 and PM10 was 16.9 ± 7.3 and 23.1 ± 10.1 μg/m3, respectively. A significant reduction in PM mass concentrations during rainfall days was observed for coarse mode (PM2.5 − 10) particles, but less reduction was found for fine (PM2.5) mass concentration. SO4
2−, NH4
+, and K+ predominated in fine particulate mode, NO3
− and Cl− predominated in fine particle mode and coarse particle mode, but Na+, Mg2+, and Ca2+ mostly existed in coarse mode. The high concentration of ammonium due to local emissions and long-range transport neutralized
sulfate and nitrate to ammonium sulfate and ammonium nitrate, which were major forms of airborne PM in Iksan. Average mass
concentrations of PM10 in daytime and at night were 57.6 and 70.0 μg m−3, and those of PM2.5 were 35.4 and 42.5 μg m−3, respectively. NO3
− and Cl− in both PM2.5 and PM10 were about double at night than in the daytime, while the rest of the chemical species were equal or a little higher at night
than in the daytime. The results suggest the formation of ammonium nitrate and chloride when high ammonia concentration and
low air temperature are allowed. Backward air trajectory analyses showed that air masses arriving at the site during yellow
dust period were transported from arid Chinese regions, which resulted in high concentrations of airborne PM mass concentrations.
In the meantime, air mass trajectories during a rainfall period were mostly from the Pacific Ocean or the East China Sea,
along with a relatively low PM concentration. 相似文献
789.
Meteorological characteristics and morphology of duststorms and other dust weather phenomena in the arid regions of East Asia
were described in order to investigate a possible role of mesoscale cloud disturbances that develop in synoptic-scale mid-latitude
cyclones in intensifying dust weather. This study is a statistical examination of conventional surface observational data
as well as satellite data obtained during April 2000–2003. In the deserts of Mongolia and northern China (e.g., the Gobi Desert)
duststorms and other weaker dust weather (i.e., dust whirls, blowing dust) frequently occur under a strong influence of synoptic-scale
cyclones; on the other hand in the Taklamakan Desert (northwestern China), dust weather phenomena occur in a less organized
fashion and may be driven mainly by local meteorological and geographical effects. A significant signal was identified, revealing
of the intensification of dust weather by the presence of convective cloud disturbances. Meteorological changes such as pressure
rise and temperature drop, typically found during the passage of cold fronts, were frequently observed in the cases of duststorms
occurring in the analysis region. However, no definite tendency was found for moisture change and wind speed in relation to
cloud activity, probably because rainfall amount is generally too low to moisten the boundary-layer air. 相似文献
790.
In spite of extensive research and development for more than 100 years to prevent and mitigate dust explosions in the process industries, this hazard continues to threaten industries that manufacture, use and/or handle powders and dusts of combustible materials. Lack of methods for predicting real dust cloud structures and flame propagation processes has been a major obstacle to prediction of course and consequences of dust explosions in practice. However, work at developing comprehensive numerical simulation models for solving these problems is now on its way. This requires detailed experimental and theoretical studies of the physics and chemistry of dust cloud generation and combustion. The present paper discusses how this kind of work will promote the development of means for prevention and mitigation of dust explosions in practice. However, progress in other areas will also be discussed, e.g. ignition prevention. The importance of using inherently safe process design, building on knowledge in powder science and technology, and of systematic education/training of personnel, is also emphasized. 相似文献