A Study of a Short-Baseline Acoustic Positioning System for Offshore Vessels

The underwater position of the beacon determined using the conventional mode of the short-baseline acoustic positioning system (SBL system) is usually incorrect due to the inaccuracy of underwater-measured sound speed, which is affected by the environment. This article presents a corrected mode of SBL system to offer a precise solution for the underwater beacon position. The corrected mode using the formulation of Euclidean geometry converges quickly and efficiently, obtaining the precise position of the beacon. Finally, a simulation of coring missions of a vessel is presented to verify the accuracy of the corrected mode of the SBL system.     

青岛市中港东区码头改造工程水下爆岩施工

青岛市中港东区码头工程水下爆岩工程量１．３万m^3,施工中采用了多段微差爆破,毫秒延迟爆破,导爆管起爆等多项为先进和成熟的施工技术,合理的施工组织,完善的施工管理,保证了工程质量,加快了工程进度。     

黄河三角洲冬半年大风预报系统

利用１９９０～１９９７年高空实况场资料作历史样本库,进行相关分析,提取典型因子场,在运用历史样本进行分型、分级的基础上,再利用与Ｔ１０６Ｌ１９数值预报产品典型因大场的平均域块距离最优相似方法,制作黄河三角洲冬半年沿海、内陆大风客观预报,经试用效果较好。     

Determination of Scenario Earthquakes for Zigong City

Ujsing deterministic methods in combination with probabilistic methods,the authors havestudied in detail the seismogeological background,seismogfnic faults and their abilities ingenerating earthquakes,the temporal and spatial distribution features of seismicity;predicted the seismicity tendency in future 50 years;and studied the expected magnitude andexpected distance of destructive earthquakes that may attack Zigong City.On such a basis,2scenario earthquakes have been determined for Zigong City.The results would be helphl forthe lecal government and authorities to work out a great earthquake emergency pre-plan andto estaplish the great earthquake fast-response system.     

Low velocity zone of upper mantle and its effect on PdSwr phase related to 670 km discontinuity

This paper studied some properties of PdSwr phase related to 670 km discontinuities in detail, and theoretically processed a preliminary analysis to this phase. We discussed the relationships between the incident angle ih of PdSwr phase with its path, epicentral distance, travel-time and relative amplitude due to low velocity zone (LVZ) of upper mantle, and preliminarily pointed out the main characters of PdSwr phase recorded in seismogram. The PdSwr phase is concentrated in range of 13.5(～96.5(. When epicentral distance is greater than 33(, the start point of PdSwr phase is relatively well distinguishable and could thus be determined more easily. When the epicentral distance is between 13.5( to 33(, the triplication of PdSwr(s travel-time curve could be slightly distinguished due to the low velocity zone and 220 km seismic velocity discontinuity of upper mantle. The relevant observed PdSwr phase should be in a more complex pattern and it should be more difficult to determine its start point.     

The absolute infrared magnitudes of type Ia supernovae

The absolute luminosities and homogeneity of early-time infrared (IR) light curves of type Ia supernovae are examined. Eight supernovae are considered. These are selected to have accurately known epochs of maximum blue light as well as having reliable distance estimates and/or good light curve coverage. Two approaches to extinction correction are considered. Owing to the low extinction in the IR, the differences in the corrections via the two methods are small. Absolute magnitude light curves in the J , H and K bands are derived. Six of the events, including five established 'branch-normal' supernovae, show similar coeval magnitudes. Two of these, supernovae (SNe) 1989B and 1998bu, were observed near maximum infrared light. This occurs about 5 d before maximum blue light. Absolute peak magnitudes of about −19.0, −18.7 and −18.8 in J , H and K respectively were obtained. The two spectroscopically peculiar supernovae in the sample, SNe 1986G and 1991T, also show atypical IR behaviour. The light curves of the six similar supernovae can be represented fairly consistently with a single light curve in each of the three bands. In all three IR bands the dispersion in absolute magnitude is about 0.15 mag, and this can be accounted for within the uncertainties of the individual light curves. No significant variation of absolute IR magnitude with B -band light curve decline rate, Δ m ₁₅( B ), is seen over the range 0.87<Δ m ₁₅( B )<1.31. However, the data are insufficient to allow us to decide whether or not the decline rate relation is weaker in the IR than in the optical region. IR light curves of type Ia supernovae should eventually provide cosmological distance estimates that are of equal, or even superior, quality to those obtained in optical studies.     

The nearby supernova factory

The Nearby Supernova Factory is an international project dedicated to the study of the nearby thermonuclear (type Ia) supernovæ. Based upon the NEAT search for the target discovery and the dedicated integral field spectrograph SNIFS for the follow‐up, the goal is to study, over a continuous period of 4 years, the spectro‐photometric evolution of ∼300 SNe Ia at z < 0.08 from −15 to +50 days in the extended optical range (320–1000 nm). This will allow to probe in detail the local Hubble diagram, SNe Ia physics and the SNe‐host galaxy correlations, serving as an unprecedented nearby benchmark for the high‐z cosmological studies to come. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

欧洲地区电离层峰值电子密度逐日变化的相关距离研究

本文采用欧洲22个台站的电离层F^₂层峰值电子密度N_mF^₂,分析了其逐日变化分量的相关距离S,着重研究了S的周日变化、季节变化及其随太阳活动和地磁活动的变化.首先用指数型函数模式来拟合任意两站间电离层逐日变化的相关系数R随间距d的变化,由此估算出逐日变化的相关距离S.详细研究了S在不同的季节（春季、夏季、秋季和冬季）,不同的地磁活动（平静和扰动）及不同的太阳活动（低、中和高）随世界时的变化（周日变化）.结果表明：（１）S的范围一般为400～1600 km;（２）S值在白天比夜间大;（３）S值具有季节变化,夏季最大,冬季最小,春秋季差异不大;（４）S值在地磁扰动时比平静时大;（５）当太阳活动低时,S值在日落到正午间要比太阳活动中或高时明显偏小,而在正午到日落间则与太阳活动中或高时差异不大.根据以上结果,我们认为：（１） 太阳辐射对电离层逐日变化的影响是大尺度的,并在白天和太阳活动高时大于晚上和太阳活动低时;（２） 地磁活动的影响也是大尺度的;（３）气象活动的影响是相对小尺度的,且逐日变化具有季节性.本文从相关尺度分析的角度,证实了电离层逐日变化来源于太阳辐射、地磁活动和气象活动因素的论断.     

基于知识规则的土地利用/土地覆被分类方法——以黑河流域为例

本文提出了一种基于知识规则的土地利用/土地覆被分类的新方法。知识规则是基于专家经验建立起来的,反映研究区内不同分类系统下各类别的地理分布特性与地理分布交叉可能性。基于黑河流域90 m 分辨率DEM、2009 年逐月1 km 分辨率NDVI,参考美国地质调查局(USGS) 1 km分辨率土地利用/土地覆被数据在欧亚大陆上各类别的聚类中心,应用在上、中、下游分别建立的知识规则,以知识规则结合最近距离的USGS 类别聚类的方法,制作了一套与USGS全球土地覆被分类标准一致的、可以用于大气模式以及陆面过程模式的黑河流域土地覆被类型分布数据。本方法分类结果与以往研究采用的类别映射方法的分类结果及实际地物影像进行对比,表明知识规则下的分类结果更能准确表达流域地表覆盖特征,对冰雪、冻土类别和沙地荒漠类别的表现更优。     

基于空间视角的风险投资研究进展与展望

风险投资有利于推动技术创新与高新技术产业发展,随着行业整体的发展以及在投资过程中表现出对信息、时间和成本等要素的较高要求,空间的约束作用逐渐受到重视,成为重要的研究视角。在此背景下,梳理总结国内外空间视角下的风险投资研究进展具有重要的启示意义,可以为相关学科研究提供借鉴与参考。论文首先明确风险投资概念并梳理相关影响因素,分析空间视角下的风险投资研究框架;在此基础上,针对风险投资机构、被投企业与投资活动,归纳风险投资的空间分布特征;再结合风险投资过程,就风险投资的本地偏好以及距离对投资策略和投资绩效方面的影响进行归纳总结;结合交通发展对空间约束作用的克服,总结现有研究对交通影响作用的探讨;最后基于已有研究进展与不足,探讨相关研究启示与展望。