广西仓储气候影响分析     

覃卫坚 《气象研究与应用》2004,25(4):19-20

对仓储中的气候影响问题进行分析,得出仓储气候影响规律。  相似文献   

2002年12月广西寒潮过程特征及数值预报产品的释用     

李生艳  苏荣在  高安宁 《气象研究与应用》2004,25(1):12-15

对2002年12月25～27日全区性寒潮天气过程爆发前后的形势进行分析,认为横槽南摆是造成这次过程的主要原因,而低纬度南支槽的配合加剧了过程的降温、降水;通过对数值预报产品的解释应用,得到一些预报全区性寒潮的指示信息。  相似文献   

基于损伤模型的圆形洞室矿震分析     

赵扬锋  潘一山  于海军 《岩土力学》2004,25(Z2):347-350

采用应变损伤模型对圆形洞室矿震的发生进行了解析分析,得到了发生矿震的洞室临界塑性区深度和临界作用力,得出损伤内变量k0,kc是决定圆形洞室矿震发生的重要参数.  相似文献   

拦蓄大气降水缓解水资源矛盾     

曹国强  程高城 《上海国土资源》2004,(1):16-18

文章为拦蓄大气降水用于农田灌溉一实例，并对该工程进行了较详细的经济效益分析。  相似文献   

储液池的抗震问题探讨   总被引：1，自引：0，他引：1  

刘云贺  王克成  陈厚群 《地震工程与工程振动》2005,25(1):149-154

应用流体固体动力耦合统一分析模型的有限元法，进行了储液池的抗震分析。分别探讨了储液池内液体的液面大幅波动、池壁刚度变化、池的深宽比等对地震响应的影响。研究结果表明：储液池壁刚度是比较敏感的物理量，弹性比刚性池壁与液体相互作用的非线性行为强，池壁所受流体的作用力大；液面波的影响也有同样规律，刚性池壁情况下考虑面波与否影响不太大，但弹性池壁却有较大影响；另外宽池比窄池的响应强。  相似文献   

Complex changes in eruption dynamics during the 79 AD eruption of Vesuvius     

Lucia Gurioli  Bruce F. Houghton  Katherine V. Cashman  Raffaello Cioni 《Bulletin of Volcanology》2005,67(2):144-159

The 79 AD eruption of Vesuvius included 8 eruption units (EU1–8) and several complex transitions in eruptive style. This study focuses on two important transitions: (1) the abrupt change from white to gray pumice during the Plinian phase of the eruption (EU2 to EU3) and (2) the shift from sustained Plinian activity to the onset of caldera collapse (EU3 to EU4). Quantification of the textural features within individual pumice clasts reveals important changes in both the vesicles and groundmass crystals across each transition boundary. Clasts from the white Plinian fall deposit (EU2) present a simple story of decompression-driven crystallization followed by continuous bubble nucleation, growth and coalescence in the eruptive conduit. In contrast, pumices from the overlying gray Plinian fall deposit (EU3) are heterogeneous and show a wide range in both bubble and crystal textures. Extensive bubble growth, coalescence, and the onset of bubble collapse in pumices at the base of EU3 suggest that the early EU3 magma experienced protracted vesiculation that began during eruption of the EU2 phase and was modified by the physical effects of syn-eruptive mingling-mixing. Pumice clasts from higher in EU3 show higher bubble and crystal number densities and less evidence of bubble collapse, textural features that are interpreted to reflect more thorough mixing of two magmas by this stage of the eruption, with consequent increases in both vesiculation and crystallization. Pumice clasts from a short-lived, high column at the onset of caldera collapse (EU4) continue the trend of increasing crystallization (enhanced by mixing) but, unexpectedly, the melt in these clasts is more vesicular than in EU3 and, in the extreme, can be classified as reticulite. We suggest that the high melt vesicularity of EU4 reflects strong decompression following the partial collapse of the magma chamber.Editorial responsibility: D.B. Dingwell  相似文献   

Multiple levels of magma storage during the 1980 summer eruptions of Mount St. Helens, WA   总被引：1，自引：0，他引：1  

K. V. Cashman  S. M. McConnell 《Bulletin of Volcanology》2005,68(1):57-75

Transitions in eruptive style—explosive to effusive, sustained to pulsatory—are a common aspect of volcanic activity and present a major challenge to volcano monitoring efforts. A classic example of such transitions is provided by the activity of Mount St. Helens, WA, during 1980, where a climactic Plinian event on May 18 was followed by subplinian and vulcanian eruptions that became increasing pulsatory with time throughout the summer, finally progressing to episodic growth of a lava dome. Here we use variations in the textures, glass compositions and volatile contents of melt inclusions preserved in pyroclasts produced by the summer 1980 eruptions to determine conditions of magma ascent and storage that may have led to observed changes in eruptive activity. Five different pyroclast types identified in pyroclastic flow and fall deposits produced by eruptions in June 12, July 22 and August 7, 1980, provide evidence for multiple levels of magma storage prior to each event. Highly vesicular clasts have H₂O-rich (4.5–5.5 wt%) melt inclusions and lack groundmass microlites or hornblende reaction rims, characteristics that require magma storage at P≥160 MPa until shortly prior to eruption. All other clast types have groundmass microlites; P_H20 estimated from both H₂O-bearing melt inclusions and textural constraints provided by decompression experiments suggest pre-eruptive storage pressures of ∼75, 40, and 10 MPa. The distribution of pyroclast types within and between eruptive deposits can be used to place important constraints on eruption mechanisms. Fall and flow deposits from June 12, 1980, lack highly vesicular, microlite-free pyroclasts. This eruption was also preceded by a shallow intrusion on June 3, as evidenced by a seismic crisis and enhanced SO₂ emissions. Our constraints suggest that magma intruded to a depth of ≤4 km beneath the crater floor fed the June eruption. In contrast, eruptions of July and August, although shorter in duration and smaller in volume, erupted deep volatile-rich magma. If modeled as a simple cylinder, these data require a step-wise decrease in effective conduit diameter from 40–50 m in May and June to 8–12 m in July and August. The abundance of vesicular (intermediate to deep) clast types in July and August further suggests that this change was effected by narrowing the shallower part of the conduit, perhaps in response to solidification of intruded magma remaining in the shallow system after the June eruption. Eruptions from July to October were distinctly pulsatory, transitioning between subplinian and vulcanian in character. As originally suggested by Scandone and Malone (1985), a growing mismatch between the rate of magma ascent and magma disruption explains the increasingly pulsatory nature of the eruptions through time. Recent fragmentation experiments Spieler et al. (2004) suggest this mismatch may have been aided by the multiple levels at which magma was stored (and degassed) prior to these events.Editorial responsibility: J Stix  相似文献   

Petrogenesis of Mafic Inclusions in Rhyolitic Lavas from Narugo Volcano, Northeastern Japan   总被引：1，自引：0，他引：1  

BAN  MASAO; TAKAHASHI  KOJI; HORIE  TAKEHIRO; TOYA  NARUHISA 《Journal of Petrology》2005,46(8):1543-1563

Mafic inclusions present in the rhyolitic lavas of Narugo volcano,Japan, are vesiculated andesites with diktytaxitic texturesmainly composed of quenched acicular plagioclase, pyroxenes,and interstitial glass. When the mafic magma was incorporatedinto the silica-rich host magma, the cores of pyroxenes andplagioclase began to crystallize (>1000°C) in a boundarylayer between the mafic and felsic magmas. Phenocryst rim compositionsand interstitial glass compositions (average 78 wt % SiO₂) inthe mafic inclusions are the same as those of the phenocrystsand groundmass glass in the host rhyolite. This suggests thatthe host felsic melt infiltrated into the incompletely solidifiedmafic inclusion, and that the interstitial melt compositionin the inclusions became close to that of the host melt (c.850°C). Infiltration was enhanced by the vesiculation ofthe mafic magma. Finally, hybridized and density-reduced portionsof the mafic magma floated up from the boundary layer into thehost rhyolite. We conclude that the ascent of mafic magma triggeredthe eruption of the host rhyolitic magma. KEY WORDS: mafic inclusion; stratified magma chamber; magma mixing; mingling; Narugo volcano; Japan  相似文献   

Future management of aquifer recharge   总被引：1，自引：3，他引：1  

Peter Dillon 《Hydrogeology Journal》2005,13(1):313-316

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Geologic storage of carbon dioxide as a climate change mitigation strategy: performance requirements and the implications of surface seepage     

R. P. Hepple  S. M. Benson 《Environmental Geology》2005,47(4):576-585

The probability that storage of carbon dioxide (CO₂) in deep geologic formations will become an important climate change mitigation strategy depends on a number of factors, namely (1) public acceptance, (2) the cost of geologic storage compared to other climate change mitigation options, and (3) the availability, capacity, and location of suitable sites. Whether or not a site is suitable will be determined by establishing that it can meet a set of performance requirements for safe and effective geologic storage. To date, no such performance requirements have been developed. Establishing effective requirements must start with an evaluation of how much CO₂ might be stored and for how long the CO₂ must remain underground to meet goals for controlling atmospheric CO₂ concentrations. Answers to these questions provide a context for setting performance requirements for geologic storage projects.According to the results presented here, geologic storage could be an effective method to ease the transition away from a fossil-fuel based economy over the next several centuries, even if large amounts of CO₂ are stored and some small fraction seeps from storage reservoirs back into the atmosphere. An annual seepage rate of 0.01% or 10^-4/year would ensure the effectiveness of geologic carbon storage for any of the projected sequestration scenarios explored herein, even those with the largest amounts of storage (1,000 s of gigatonnes of carbon-GtC), and still provide some safety margin. Storing smaller amounts of carbon (10 s to 100 s of GtC) may allow for a slightly higher seepage rate on the order of 0.1% or 10^-3/year. Based on both the large capacity of geologic storage formation and the likelihood of achieving leakage rates much lower than the rates estimated here, geologic storage appears to be a promising mitigation strategy.  相似文献