One-dimensional electric field structure of an outer gap accelerator – III. Location of the gap and the gamma-ray spectrum     

Kouichi Hirotani  Shinpei Shibata 《Monthly notices of the Royal Astronomical Society》2001,325(3):1228-1240

We investigate a stationary particle acceleration zone in the outer magnetosphere of an obliquely rotating neutron star. The charge depletion as a result of global current causes a large electric field along the magnetic field lines. Migratory electrons and/or positrons are accelerated by this field to radiate curvature gamma-rays, some of which collide with the X-rays to materialize as pairs in the gap. As a result of this pair-production cascade, the replenished charges partially screen the electric field, which is self-consistently solved together with the distribution of particles and gamma-rays. If no current is injected at either of the boundaries of the accelerator, the gap is located around the so-called null surface, where the local Goldreich–Julian charge density vanishes. However, we find that the gap position shifts outwards (or inwards) when particles are injected at the inner (or outer) boundary. We apply the theory to the seven pulsars whose X-ray fields are known from observations. We show that the gap should be located near to or outside of the null surface for the Vela pulsar and PSR B1951+32, so that their expected GeV spectrum may be consistent with observations. We then demonstrate that the intrinsically large TeV flux from the outer gap of PSR B0540–69 is absorbed by the magnetospheric infrared photons, causing it to be undetectable. We also point out that the electrodynamic structure and the resultant GeV emission properties of millisecond pulsars are similar to young pulsars.  相似文献   

Development of a facility for analysis of natural ^32Si     

《中国地球化学学报》2006,25(B08):199-200

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Geochemische und 13C/12C-isotopenchemische Untersuchung zur Herkunft der Kohlensäure in mineralhaltigen Wässern Nordhessens (Deutschland)     

M. Dietzel  H. Schwecke  A. Hirschfeld  M. Rhring  M. E. Bttcher 《洁净——土壤、空气、水》1997,25(4):191-201

Geochemical and ¹³C/¹²C-isotopical Investigation of Mineral Waters in Northern Hessia (Germany) and the Origin of their CO₂ Content The dissolved carbonate originates from three sources: 1. biogenetic soil-CO₂, 2. volcanic CO₂ related to the evaporites of the Zechstein formation, and 3. carbonate derived from the dissolution of limestones and dolomites. Miocenic basaltic melts penetrated the evaporites of the Zechstein, and the related CO₂ was trapped in the intra- and intergranulars of the salt minerals. Circulating meteoric waters dissolve the salt minerals releasing CO₂ gas. Thus, the occurrence of basalt is related to the CO₂ contents of the evaporites, and the dissolution of only small amounts of salts rich in CO₂ may result in a high concentration of carbonic acid. In waters rich in carbonate, where volcanic CO₂ dominates over the other two sources of carbon, a δ¹³C-value of “salt-CO₂” of about –1‰ (PDB) is obtained. Water with less dissolved carbonate species have smaller quantities of salt-CO₂ down to about 20%.  相似文献   

利用Win 32 API通信函数设计串行通信程序   总被引：5，自引：1，他引：4  

袁志勇  苏光奎  杨维均 《测绘信息与工程》2000,(4):33-37

在Windows95/98OS和VisualC^ 5.0/6.0软件开发平台下,介绍了利用Win32API串行通信函数实现PC机串行通信的技术及编程方法,并给出了一处在后台房问串口的通信程序示例。  相似文献   

河北山前平原地下水^32Si年龄初探   总被引：6，自引：3，他引：3  

刘存富  王佩仪 《水文地质工程地质》1999,26(2):1-3,9

＾３２Ｓｉ是放射性同位素,半衰期约１４０ａ可以测定５０～１０００ａ地下水的年龄,本文用Ｆｅ（ＯＨ）３共沉淀法从天然水中提取ＳｉＯ２回收率可达３０％～９８％,然后提取和纯化＾３２Ｐ,将Ｈ３ＰＯ４溶液和Ｐｉｃｏ－ｆｌｏｕｒ＾ＴＭＬＬＴ混合制备计数溶液,用液体闪烁计数法测量中＾３２Ｐ的放射性,本底计数为４．８０ｃｐｈ,仪器效率为４５．３４％,然后用公式计算样品的＾３２Ｓｉ放射性浓度和地下水的＾３２Ｓｉ年  相似文献   

A study of dissipation of wind-waves by mud at Cassino Beach,Brazil: Prediction and inversion     

W. Erick Rogers  K. Todd Holland 《Continental Shelf Research》2009

The impact of a non-rigid seafloor on the wave climate at Cassino Beach, Brazil, May–June 2005 is studied using field measurements and a numerical wave model. The measurements consist of wave data at four locations; rheology and mud thickness from grab samples; and an estimate of the horizontal distribution of mud based on echo-soundings. The dissipation of waves by a non-rigid bottom is represented in the wave model by treating the mud layer as a viscous fluid. Applied for 431 time periods, the model without this type of dissipation has a strong tendency to overpredict nearshore wave energy, except during a period of large storm waves. Two model variations which include this dissipation have a modest tendency to underpredict the nearshore wave energy. An inversion methodology is developed and applied to infer an alternate mud distribution which, when used with the wave model, yields the observed waveheights.  相似文献   

Impacts of stormwater runoff in the Southern California Bight: Relationships among plume constituents     

Kristen M. Reifel  Scott C. Johnson  Paul M. DiGiacomo  Michael J. Mengel  Nikolay P. Nezlin  Jonathan A. Warrick  Burton H. Jones 《Continental Shelf Research》2009,29(15):1821-1835

The effects from two winter rain storms on the coastal ocean of the Southern California Bight were examined as part of the Bight ‘03 program during February 2004 and February–March 2005. The impacts of stormwater from fecal indicator bacteria, water column toxicity, and nutrients were evaluated for five major river discharges: the Santa Clara River, Ballona Creek, the San Pedro Shelf (including the Los Angeles, San Gabriel, and Santa Ana Rivers), the San Diego River, and the Tijuana River. Exceedances of bacterial standards were observed in most of the systems. However, the areas of impact were generally spatially limited, and contaminant concentrations decreased below California Ocean Plan standards typically within 2–3 days. The largest bacterial concentrations occurred in the Tijuana River system where exceedances of fecal indicator bacteria were noted well away from the river mouth. Maximum nitrate concentrations (~40 μM) occurred in the San Pedro Shelf region near the mouth of the Los Angeles River. Based on the results of general linear models, individual sources of stormwater differ in both nutrient concentrations and the concentration and composition of fecal indicator bacteria. While nutrients appeared to decrease in plume waters due to simple mixing and dilution, the concentration of fecal indicator bacteria in plumes depends on more than loading and dilution rates. The relationships between contaminants (nutrients and fecal indicator bacteria) and plume indicators (salinity and total suspended solids) were not strong indicating the presence of other potentially important sources and/or sinks of both nutrients and fecal indicator bacteria. California Ocean Plan standards were often exceeded in waters containing greater than 10% stormwater (<28–30 salinity range). The median concentration dropped below the standard in the 32–33 salinity range (1–4% stormwater) for total coliforms and Enterococcus spp. and in the 28–30 salinity range (10–16% stormwater) for fecal coliforms. Nutrients showed a similar pattern with the highest median concentrations in water with greater than 10% stormwater. Relationships between colored dissolved organic matter (CDOM) and salinity and between total suspended solids and beam attenuation indicate that readily measurable, optically active variables can be used as proxies to provide at least a qualitative, if not quantitative, evaluation of the distribution of the dissolved, as well as the particulate, components of stormwater plumes. In this context, both CDOM absorption and the beam attenuation coefficient can be derived from satellite ocean color measurements of inherent optical properties suggesting that remote sensing of ocean color should be useful in mapping the spatial areas and durations of impacts from these contaminants.  相似文献   

野外实验场地球物理电磁数据采集与分析   总被引：3，自引：0，他引：3  

李建华  林品荣 《地球物理学进展》2012,27(4):1377-1384

地球物理电磁数据观测实验场的建立在国内仍属空白,根据开展电磁法的方法技术要求,我们率先选择具备条件的已知矿区作为实验场地,开展了包括国内、外多种型号电磁法仪器(GDP 32Ⅱ、V8、DEM-V、DJS-8A)的相同装置下的同剖面同点位对比试验.对野外实验场上所开展的不同方法每种仪器的数据采集方式与取得结果进行比较分析,并与地质资料进行了结合分析;通过地球物理电磁数据的综合观测研究,形成标准化的数据,将对电磁法仪器开发、仪器引进提供实验检测场地与标准的检测数据,促进地球物理电磁探测技术的研究与发展.  相似文献   

世界地质遗迹保护和地质公园建设的现状和展望   总被引：35，自引：1，他引：34  

赵汀  赵逊 《地质论评》2005,51(3):301-308

在2004年6月在中国北京召开了第一届世界地质公园大会和2004年8月在意大利佛罗伦萨举行第32届国际地质大会,来自五大洲数十个国家的地质学家和地质公园管理者发言,展示了各国地质遗产保护现状,地质公园建设中地质遗产的科学研究,公众教育;保护方法技术;与文化遗产的关系;与城市和区域发展规划的关系;与旅游产业发展的关系,地质公园与国家公园的关系;欧、美及非洲、大洋洲和亚洲各国地质公园发展前景等。他山之石,可以攻玉。对照各国的近况,我国在地质遗产的研究和保护方面要保持世界领先地位,在相关法规建设,地学背景研究,人才培养等方面还有大量工作要做。  相似文献   

水平井技术在秦皇岛32—6油田西区底水油藏中的开发实践     

胡勇  廖新武  许聘  杨庆红 《海洋地质译丛》2010,(1):90-95

随着油田开发技术的进步，水平井开采技术日趋完善，在底水油藏应用中取得了明显效果。秦皇岛32—6油田西区是典型的底水油藏，该区主体于2002年采用定向井投入开发，投产后基本没有无水采油期，底水锥进、突破很快，经过6年多的开发已进入高含水期，至2008年初，含水83．7％，采出程度5．05％，开发效果较差。基于水平井开发底水油藏试验研究，总结出影响该区水平井开发效果两个主要因素：水平段距离油水界面高度和水平井区隔夹层分布状况。在此基础之上，通过开展隔夹层及剩余油研究，在明下段有利位置布水平井6口，并在实施中应用了随钻跟踪及先进的完井技术。该区6口水平调整井投产后初期产能约是定向井的3倍，全油田预计最终采收率提高0．36％，取得了良好的效益。  相似文献