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排序方式: 共有603条查询结果,搜索用时 671 毫秒
301.
天然气集输站泄漏监控系统研究 总被引:1,自引:0,他引:1
为克服目前天然气集输站站控系统存在的主要技术问题,探讨了建立泄漏监控安全系统的技术要求.该系统应用负压波检漏技术、模式识别技术和虚拟仪器技术,实现了.对天然气泄漏的信号检测、处理、传输和实时动态显示等.借助于这些技术开发的天然气泄漏监控系统,具有数据处理准确可靠,精度高,误报率低等特点.通过该系统,可以及时获取相关参数和信息,实现早期预警,降低天然气泄漏的事故风险. 相似文献
302.
Dressel M 《Die Naturwissenschaften》2007,94(7):527-541
Low-dimensional organic conductors could establish themselves as model systems for the investigation of the physics in reduced
dimensions. In the metallic state of a one-dimensional solid, Fermi liquid theory breaks down and spin and charge degrees
of freedom become separated. But the metallic phase is not stable in one dimension: as the temperature is reduced, the electronic
charge and spin tend to arrange themselves in an ordered fashion due to strong correlations. The competition of the different
interactions is responsible for which broken-symmetry ground state is eventually realized in a specific compound and which
drives the system toward an insulating state. Here, we review the various ordering phenomena and how they can be identified
by optic and magnetic measurements. While the final results might look very similar in the case of a charge density wave and
a charge-ordered metal, for instance, the physical cause is completely different. When density waves form, a gap opens in
the density of states at the Fermi energy due to nesting of the one-dimension Fermi surface sheets. When a one-dimensional
metal becomes a charge-ordered Mott insulator, on the other hand, the short-range Coulomb repulsion localizes the charge on
the lattice sites and even causes certain charge patterns. We try to point out the similarities and conceptional differences
of these phenomena and give an example for each of them. Particular emphasis will be put on collective phenomena that are
inherently present as soon as ordering breaks the symmetry of the system. 相似文献
303.
Post‐catastrophe recovery and financial liquidity have long challenged small Caribbean islands. These states are vulnerable to multifarious natural hazards that often cause considerable socioeconomic dislocation. Such events inflict heavy losses on businesses and households, and significantly disrupt all aspects of government operations. After Hurricane Ivan devastated the economies of some islands in September 2004—with estimated losses of as much as 200 per cent of gross domestic product in some cases—regional governments, aided by the World Bank and international donors, approved the creation of a regional catastrophe insurance scheme. This parametric‐based mechanism is underpinned by derivatives‐based catastrophe modelling whose outputs determine policy triggers and pay outs. Hazard models, particularly catastrophe models, are not widely accepted as yet. Despite recent advancements, major concerns have rendered them peripheral tools for many establishments. This paper reviews the region's vulnerabilities and examines constraints on the application of these models and suggests a means of improving their efficacy and acceptability. 相似文献
304.
为探究山区河道型水库中,滑坡涌浪产生的冲击波对重力坝漫坝的影响,运用三维物理模型试验方法,探究近坝库区滑坡涌浪冲击波到达坝前时,坝前首浪最大振幅与涌浪漫坝体积的关系。结果显示,坝前首浪振幅沿坝体两岸向中间减小,坝段中心容易出现最小值;漫坝体积随首浪振幅的增加而增大。研究结果表明:坝前首浪最大振幅与涌浪漫坝体积两者呈正相关关系,漫坝体积受滑坡体角度与滑坡体积影响显著,进而构建漫坝体积计算方法。研究结果能够为大坝安全评估提供一定参考依据。 相似文献
305.
Either in the chemical process plants or in the underground infrastructures, the isolation seal is regularly used to separate the working sections and inactive sections, or to isolate the possible explosion sites in order to avoid any domino effects. Due to differences in accumulation space or ignition point locations, pressure on the seal can vary when an explosion occurs. Thus, the safety and reliability of seals are crucial to maintaining safety in process industry. This paper focuses on seals constructed with concrete and loess materials, and examines the dynamic response characteristics of the gas explosion wave on the seal through sample experiments and numerical simulation metods. The study proposes an optimized design for the explosion-proof structure of the wedge-shaped and spherical seal, which can provide a technical basis for the explosion-proof and anti-explosion measures of various sealed walls. These research findings can also serve as a basis for improving the construction quality of seals. 相似文献
306.
The production and storage of liquefied petroleum gas (LPG) is gradually becoming larger and more intensive, which greatly increases the risk of the domino effect of an explosion accident in a storage tank area while improving production and management efficiency. This paper describes the construction of the domino effect scene of an explosion accident in an LPG storage tank area, the analysis of the characteristics of the LPG tank explosion shock wave and the target storage tank failure, and the creation of an ANSYS numerical model to derive the development trend and expansion law of the domino accident in the LPG storage tank area. The research showed that: 400 m3 tank T1 explosion shock waves spread to T2, T4, T5, T3, and T6, and the tank overpressures of 303 kPa, 303 kPa, 172 kPa, 81 kPa, and 61 kPa respectively. The critical values of the target storage tank failure overpressure-range threshold were 70 kPa and 60 m. After the explosion of the initial unit T1 tank, at 38 ms, the T2 and T4 storage tanks failed and exploded; at 56 ms, the T5 storage tank exploded for the third time; at 82 ms, the T3 storage tank exploded for the fourth time; and at 102 ms, the T6 storage tank exploded for the fifth time. With the increase of explosion sources, the failure overpressure of the target storage tank increased, and the interval between explosions continuously shortened, which reflected the expansion effect of the domino accident. The domino accident situation deduction in the LPG storage tank area provided a scientific basis for the safety layout, accident prevention and control, emergency rescue, and management of a chemical industry park. 相似文献
307.
应用LS-DYNA软件建立了北京比较典型的2层地铁车站有限元模型,通过数值模拟方法分析地铁车站发生内部爆炸时,爆炸波在地铁车站内部的传播规律。研究表明:①在0.3m/kg~(1/3)Z1.6m/kg~(1/3)范围内,车站内部超压峰值可用Henrych经验公式估算;②爆炸波在地铁车站的封闭空间不断出现反射、绕射现象,使得结构构件遭受多次冲击作用;③楼梯口起到了一定的泄爆作用。本文研究结果可供地铁车站的抗爆设计与安全分析参考。 相似文献
308.
深孔爆破孔底充填缓冲吸能材料减震试验研究 总被引:1,自引:1,他引:0
通过对影响爆破震波各种主要因素的分析,针对深孔爆破采用孔底装填吸能缓冲材料,来削减炸药爆炸在孔底的冲击压力和吸收部分能量,从而达到降低爆破震动对周边建(构)物影响的目的。并进行现场爆破试验,对爆破震动波进行测试,同时对减震爆破装药和非减震的常规爆破装药进行比较,获得的测试数据证明,采用孔底装填吸能缓冲材料其减震率达到3.23%~35.19%。 相似文献
309.
310.
Kamal El Kadi Abderrezzak André Paquier Bernard Gay 《Environmental Fluid Mechanics》2008,8(2):169-198
This paper reports a numerical study on dam-break waves over movable beds. A one-dimensional (1-D) model is built upon the
Saint-Venant equations for shallow water waves, the Exner equation of sediment mass conservation and a spatial lag equation
for non-equilibrium sediment transport. The set of governing equations is solved using an explicit finite difference scheme.
The model is tested in various idealized experimental cases, with fairly good agreement between the numerical predictions
and measurements. Discrepancies are observed at the earlier stage of the dam-break wave and around the dam location due to
no vertical velocity component being taken into account. Sensitivity tests confirm that the friction coefficient is an important
parameter for the evaluation of sediment transport processes operating during a dam-break wave. The influence of the non-equilibrium
adaptation length (or the lag distance) is negligible on the wavefront celerity and weak on the free surface and bed profiles,
which indicates that one may ignore the spatial lag effect in dam-break wave studies. Finally, the simulation of the Lake
Ha!Ha! dyke-break flood event shows that the model can provide relevant results if a convenient formula for computing the
sediment transport capacity and an appropriate median grain diameter of riverbed material are selected. 相似文献