CINRAD/SB雷达伺服上电故障诊断分析   总被引：1，自引：1，他引：0  

潘新民  柴秀梅  崔炳俭  黄跃青  徐俊领 《气象科技》2011,39(2):212-216

在详细介绍CINRAD/SB雷达数字伺服系统加电控制、天线状态信号流程的基础上,分析出数字伺服系统无法上电3方面原因：负载过载导致空气开关保护性断电;伺服系统加电信号不正常;制动器过流导致温度超限。总结了CINRAD/SB雷达伺服系统无法上电故障的分析方法和诊断流程。通过诊断流程详细论述两例伺服无法上电的复杂故障分析和排除过程,以及在台站无配件更换情况下,充分利用雷达线路特点暂时采用应急方法尽快恢复雷达运转的方法,保证灾害性天气监测的需求。为新一代天气雷达技术支持和保障提供借鉴。  相似文献   

长江三角洲近46 a气温和降水的变化趋势   总被引：2，自引：2，他引：0       下载免费PDF全文

潘敖大  王珂清  曾燕  谢志清  苗茜 《大气科学学报》2011,34(2):180-188

利用长江三角洲地区84个气象站观测数据,分析了长江三角洲1961—2006年气温和降水的时空变化趋势。结果表明,46 a间长江三角洲地区年平均气温上升趋势显著,冬季平均气温的增温幅度最大,春、秋次之。增温显著区域与城市带分布区域吻合。极端最低气温有明显上升,而年极端低温事件日数的下降趋势显著。部分地区的极端最高气温呈上升趋势,在城市密集带尤为突出。年降水量没有明显的变化趋势,但降水的季节分配有所变化,冬、夏季降水量呈现显著上升趋势,秋季降水量明显下降,春季没有明显变化。  相似文献   

Analytical solution for two-phase flow in a wellbore using the drift-flux model   总被引：1，自引：0，他引：1  

Lehua Pan  Stephen W. Webb  Curtis M. Oldenburg 《Advances in water resources》2011,34(12):1656-1665

This paper presents analytical solutions for steady-state, compressible two-phase flow through a wellbore under isothermal conditions using the drift flux conceptual model. Although only applicable to highly idealized systems, the analytical solutions are useful for verifying numerical simulation capabilities that can handle much more complicated systems, and can be used in their own right for gaining insight about two-phase flow processes in wells. The analytical solutions are obtained by solving the mixture momentum equation of steady-state, two-phase flow with an assumption that the two phases are immiscible. These analytical solutions describe the steady-state behavior of two-phase flow in the wellbore, including profiles of phase saturation, phase velocities, and pressure gradients, as affected by the total mass flow rate, phase mass fraction, and drift velocity (i.e., the slip between two phases). Close matching between the analytical solutions and numerical solutions for a hypothetical CO₂ leakage problem as well as to field data from a CO₂ production well indicates that the analytical solution is capable of capturing the major features of steady-state two-phase flow through an open wellbore, and that the related assumptions and simplifications are justified for many actual systems. In addition, we demonstrate the utility of the analytical solution to evaluate how the bottomhole pressure in a well in which CO₂ is leaking upward responds to the mass flow rate of CO₂-water mixture.  相似文献   

不同量级磁暴对新沂地震台地电阻率的影响     

韩晓飞  潘存英  李飞  纪加迎 《地震地磁观测与研究》2011,32(4):35-39

探讨强烈磁暴对新沂地震台地电阻率测最的影响.根据磁暴效应,得出对地电阻率的影响,从而进行不同量级磁暴对江苏省新沂地震台地电阻率的影响分析.同时分析各测向产生的差异性及原因.由于新沂地震台地电阻率测量采用正反向双向供电,磁暴对地电阻率的影响量很小,其形态仍存在同步变化.如果采取减少每次测量的供电时间、供电次数,加大供电电...  相似文献   

System identification and damage evaluation of degrading hysteresis of reinforced concrete frames     

Chin‐Hsiung Loh  Chien‐Hong Mao  Jhih‐Ren Huang  Tso‐Chien Pan 《地震工程与结构动力学》2011,40(6):623-640

In this study, signal processing approaches and nonlinear identification are used to measure seismic responses of reinforced concrete (RC) structures using the shaking table test. To analyze structural nonlinearity, an equivalent linear system with time‐varying model parameters, singular spectrum analysis to elucidate residual deformation, and wavelet packet transformation analysis to yield the energy distribution among components are adopted to detect the nonlinearity. Then, damage feature extraction is conducted using both the Holder exponent and the Level‐1 detail of the discrete wavelet component. Finally, the modified Bouc‐Wen hysteretic model and the system identification process are employed to the shaking table test data to evaluate the physical parameters, including the stiffness degradation, the strength deterioration and the pinching hysteresis. Finally, the identified stiffness and strength degradation functions from the test data of RC frames in relation to the degree of ground shaking, damage index and the identified nonlinear features are discussed. Based on the proposed method, both signal‐based and model‐based identifications, the relationship between the damage occurrence and severity of structural damage can be identified. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

中国历史地震烈度表研究   总被引：10，自引：1，他引：9       下载免费PDF全文

鄢家全  张志中  王健  温增平  俞言祥  刘爱文  潘华  吕红山  郝玉芹 《地震学报》2011,33(4):515-531

在比较分析以往烈度表的基础上,着重增加了社会反响标志;对Ⅹ-Ⅻ度的房屋建筑物和地表现象标志进行了调整与补充,完善了作为12阶烈度表相应的《中国历史地震烈度表》.文中对烈度表的各项标志作了简要说明,并列举了国内外10次历史地震事件的评定实例.本文提出的历史地震烈度表,保持了以往烈度表的适用性与一致性.  相似文献   

Sources and distributions of tetraether lipids in surface sediments across a large river-dominated continental margin   总被引：3，自引：0，他引：3  

Chun Zhu  Johan W.H. Weijers  Thomas WagnerJian-Ming. Pan  Jian-Fang ChenRichard D. Pancost 《Organic Geochemistry》2011,42(4):376-386

Glycerol dialkyl glycerol tetraether (GDGT)-based proxies are increasingly used in modern carbon cycling and palaeoenvironmental investigations. It is therefore crucial to examine the robustness (sources, transport and degradation) of all GDGT-based proxies in continental margins, where sedimentation rates and extent of carbon cycling are high. We have analyzed the distributions of GDGTs in surface sediments from the Lower Yangtze River and East China Sea (ECS) shelf. The results revealed multiple sources and complex shelf processes that govern the distributions. The isoprenoid GDGT-inferred sea surface temperatures (SSTs) are robust and reflect the satellite-derived annual mean SSTs on the shallow ECS shelf, confirming an origin from surface water column-dwelling crenarchaeota. The input from methanogen-sourced, isoprenoid GDGTs is significant in the river surface sediments but they are almost absent from the ECS shelf. Branched GDGTs are also abundant in the river sediments, but ca. 95% are degraded in the Yangtze estuary, a much greater extent than observed for other terrigenous organic matter (OM) proxies. There is also evidence for production of branched GDGTs in the oxic ECS shelf water column and the anoxic sediments/waters of the Lower Yangtze River. As a result, branched GDGT-based proxies in the lower river and ECS surface sediments do not reflect the catchment environmental conditions. The effective degradation in the estuary and widespread aquatic contributions of branched GDGTs improves our understanding of how to use branched GDGT-based proxies in marginal seas.  相似文献   

Electron paramagnetic resonance spectroscopy of Fe<Superscript>3+</Superscript> ions in amethyst: thermodynamic potentials and magnetic susceptibility     

Gobburu SivaRamaiah  Jinru Lin  Yuanming Pan 《Physics and Chemistry of Minerals》2011,38(2):159-167

Single-crystal and powder electron paramagnetic resonance (EPR) spectroscopic studies of natural amethyst quartz, before and after isochronal annealing between 573 and 1,173 K, have been made from 90 to 294 K. Single-crystal EPR spectra confirm the presence of two substitutional Fe³⁺ centers. Powder EPR spectra are characterized by two broad resonance signals at g = ~10.8 and 4.0 and a sharp signal at g = 2.002. The sharp signal is readily attributed to the well-established oxygen vacancy electron center E ₁′. However, the two broad signals do not correspond to any known Fe³⁺ centers in the quartz lattice, but are most likely attributable to Fe³⁺ clusters on surfaces. The absolute numbers of spins of the Fe³⁺ species at g = ~10.8 have been calculated from powder EPR spectra measured at temperatures from 90 to 294 K. These results have been used to extract thermodynamic potentials, including Gibbs energy of activation ΔG, activation energy E _a, entropy of activation ΔS and enthalpy of activation ΔH for the Fe³⁺ species in amethyst. In addition, magnetic susceptibilities (χ) have been calculated from EPR data at different temperatures. A linear relationship between magnetic susceptibility and temperature is consistent with the Curie–Weiss law. Knowledge about the stability and properties of Fe³⁺ species on the surfaces of quartz is important to better understanding of the reactivity, bioavailability and heath effects of iron in silica particles.  相似文献   

Modelling fluid flow through a single fracture with different contacts using cellular automata     

Peng-Zhi Pan  Xia-Ting FengDing-Ping Xu  Lin-Fang ShenJin-Bao Yang 《Computers and Geotechnics》2011

The representation of the surface of a rock fracture and a numerical method to simulate fluid flow in single fractures are the keys to understanding the hydraulic behaviour of rock fractures. In this paper, a cellular automaton (CA) approach is used to generate the single fracture structure, which is assumed to be composed of contacts and voids. We develop a CA evolution rule to produce a contact area, and randomly model a single rock fracture with different contact ratios to reflect natural fracture properties such as dead voids, islands and tortuous flow path. Then, based on the localisation theory of a CA, a numerical method to simulate fluid flow in single fractures with contacts is developed. In this method, the fracture is discretised into a system composed of cell elements. Different apertures, i.e., zero for contacts and non-zero for voids, are assigned to each cell element. Therefore, the contribution of the cell elements in a contact on a cell’s transmissivity can be ignored completely. The local transmissivity is assumed to conform to the cubic law. The fluid flow in a fracture with different contact situations is then modelled using the method established in this paper. The fluid flow path, flow velocity and fluid head distributions as well as the channel flow in the fracture are well-modelled. The flow behaviour of the fracture strongly depends on the effective fluid flow path.  相似文献   

鄂尔多斯盆地镇泾区块延长组长81储层成岩作用特征及其对储集物性的影响   总被引：1，自引：0，他引：1       下载免费PDF全文

张霞  林春明  陈召佑  周健  潘峰  俞昊 《地质科学》2011,46(2):530-548

鄂尔多斯盆地镇泾区块上三叠统延长组长81储层具有成分成熟度低,结构成熟度中等到好的特点,岩性以岩屑长石砂岩和长石岩屑砂岩为主.长81砂岩属于特低孔特低渗储层,以次生溶蚀粒间孔为主要储集空间.目前储层正处于中成岩阶段A期,主要发育压实、胶结、溶解和交代4种成岩作用类型.机械压实作用是造成长81储层埋深小于2000 m砂岩...  相似文献