声速剖面仪水下探头软硬件设计

简要阐述了直接测量式声速剖面仪的测量原理及水下机探头的体系结构;并进一步介绍了自容式和拖缆式两种结构的声速剖面仪的控制单元、模数转换、数据存储、数据提取、控制命令的响应和执行、系统状态的检查及设备的可靠性处理等模块的软硬件实现方法。     

十六位模数转换器AD7705及其应用

AD7705是AD公司最近推出的十六位模数转换器。我们主要介绍了它的功能和特点，给出了基于AD7705实际应用的硬件、软件设计方法，以及部分程序源代码，总结了实际应用中必须注意的几个技术问题。     

Relationship between the Landslides Triggered by the Tongwei M7 1/2 Earthquake in 1718 AD and the Disappearance of Yongning Ancient Town

Although China''s historical earthquake documentation is relatively rich, it is not all based on scientific records. Therefore, the verification of the seismic information in historical records can effectively avoid exaggerating or underestimating the damage they produced. In this paper, we analyze the detailed information of the 1718 AD Tongwei M7 1/2 earthquake through field surveys, document sorting, and manual visual interpretation of UAV images. Major conclusions are listed as follows:①The low-level terraces of Weihe River between Gangu and Wushan are fully developed with flatted surface, and the residents here are mostly killed by house collapses. In addition, the disappearance of Yongning Ancient Town is not directly related to the earthquake-induced landslides; ② In fact, "Yongning Town is entirely buried by the earthquake" in the historical records describes the phenomenon that loess dust has pervaded the entire Weihe Valley. These dust grains are produced by the sliding of earthquake-induced landslides. Thus, there is no possibility that large-scale landslides have slipped over Weihe bedrock and buried Yongning Town; ③After the earthquake, survivors abandoned the ruins and selected a new site to live. They built a new town named "Pan''an (means always peaceful in the future)". earthquake-induced landslides may be the reason of burying the residential areas on valley-side slopes, while those locations inside the valley are associated with the amplification effect of ground vibration. On the basis of compiling historical seismic data, scientific methods are used to explore the real meaning of these documents, for the purpose of providing basic data for the risk evaluation of strong historical earthquakes.     

Tree-ring dates on two pre-Little Ice Age advances in Glacier Bay National Park and Preserve, Alaska, USA

Two interstadial tree ring-width chronologies from Geikie Inlet, Glacier Bay Southeast, Alaska were built from 40 logs. One of these chronologies has been calendar dated to AD 224–999 (775 yr) crossdating with a living ring-width chronology from Prince William Sound, Alaska. Trees in this chronology were likely killed through inundation by sediments and meltwater from the advancing Geikie Glacier and its tributaries ca. AD 850. The earlier tree-ring chronology spans 545 yr and is a floating ring-width series tied to radiocarbon ages of about 3000 cal yr BP. This tree-ring work indicates two intervals of glacial expansion by the Geikie Glacier system toward the main trunk glacier in Glacier Bay between 3400 and 3000 cal yr BP and again about AD 850. The timing of both expansions is consistent with patterns of ice advance at tidewater glaciers in other parts of Alaska and British Columbia about the same time, and with a relative sea-level history from just outside Glacier Bay in Icy Strait. This emerging tree-ring dated history builds on previous radiocarbon-based glacial histories and is the first study to use tree-ring dating to assign calendar dates to glacial activity for Glacier Bay.     

A 2000-yr-long multi-proxy lacustrine record from eastern Baffin Island, Arctic Canada reveals first millennium AD cold period

We generate a multi-proxy sub-centennial-scale reconstruction of environmental change during the past two millennia from Itilliq Lake, Baffin Island, Arctic Canada. Our reconstruction arises from a finely subsectioned ²¹⁰Pb- and ¹⁴C-dated surface sediment core and includes measures of organic matter (e.g., chlorophyll a; carbon–nitrogen ratio) and insect (Diptera: Chironomidae) assemblages. Within the past millennium, the least productive, and by inference coldest, conditions occurred ca. AD 1700–1850, late in the Little Ice Age. The 2000-yr sediment record also reveals an episode of reduced organic matter deposition during the 6th–7th century AD; combined with the few other records comparable in resolution that span this time interval from Baffin Island, we suggest that this cold episode was experienced regionally. A comparable cold climatic episode occurred in Alaska and western Canada at this time, suggesting that the first millennium AD cold climate anomaly may have occurred throughout the Arctic. Dramatic increases in aquatic biological productivity at multiple trophic levels are indicated by increased chlorophyll a concentrations since AD 1800 and chironomid concentrations since AD 1900, both of which have risen to levels unprecedented over the past 2000 yr.     

基于AD598的伸缩仪放大电路设计

伸缩仪多用于地壳形变观测,但其在工程中亦有较大的应用前景.现用的放大电路精度高但电路复杂、成本过高,造成其工程应用方面的局限性.介绍基于单片式线位移差动变压器(LVDT)信号调节器AD598设计的全新伸缩仪放大电路,作为伸缩仪放大电路的补充,体现了其在工程应用中简单可靠、成本低的优势.     

基于AD7762的广域电磁接收机采集器设计

根据广域电磁仪系统分频段发送和接收包含多个频率的伪随机电磁信号,以及接收机采集电磁信号时要求高频段高速采样,低频段高精度低速采样的特点,选择了符合接收机采集特性的高性能、高速度24位模数转换器AD7762,简要介绍了AD7762的特性,设计了基于AD7762的广域电磁采集器,并从硬件、软件方面给出了实现方案.实验结果表明,AD7762在广域电磁接收机应用中取得了良好的性能指标.     

Morphological response of a barrier island system on a catastrophic event: the AD 1634 North Sea storm

The AD 1634 North Sea storm is one of the most catastrophic storms along the Wadden Sea coast of Denmark. In this study we show how pre‐1634 storm morphology exerted a strong control on the resulting post‐storm coastal morphology. Erosional responses associated with the storm were barrier breaching, dune scarping and shoreface erosion and accretionary responses were washover deposition, shoreface healing and barrier‐island formation. Local sediment sources appeared to have a particularly strong influence on post‐storm coastal evolution and allowed a very rapid formation of a barrier shoal which resulted in several kilometres of coastal progradation. Sediment budgets suggest that formation of the barrier shoal was possible, but the sediment transport rates in the decades after the 1634 storm, must have been two to three times higher than present‐day rates. The study demonstrates that catastrophic storms are capable of moving large amounts of sediments over relatively short time‐periods and can create barrier shoals, whereas moderate storms mostly rework the shoal or barrier and create more local erosion and/or landward migration. Catastrophic storms substantially influence long‐term and large‐scale coastal evolution, and storms may positively contribute to the sediment budget and promote coastal progradation in coastal areas with longshore sediment convergence. Copyright © 2015 John Wiley & Sons, Ltd.     

RESEARCH ON ACTIVITIES OF THE GUDIAN FAULT IN SONGYUAN,JILIN PROVINCE

The Gudian Fault in the southwest of Songyuan is an important fault in the central depression of the Songliao Basin. It was recognized from the petroleum exploration data. Based on the data, we conducted shallow seismic exploration, drilling exploration, age determination(OSL) and topography measurement. The fault features and its motion characteristics are analyzed with the results of shallow seismic exploration. With stratigraphic correlation and optical stimulated luminescence dating, the latest active age of the fault is determined. The surface relief of the region to the southeast of the drilling site is relatively larger than surrounding places. An 800m long section across the fault was measured by GPSRTK, and the deformation amount across the zone was calculated. Four conclusions are drawn in this paper:(1) The Gudian Fault is arcuate in shape and shows a property of inverse fault with a length of about 66km in the reflection interface T1(bottom of the upper Cretaceous Nenjiang Group). (2) The middle part of the fault rupture is wider than the ends, narrowing or dying out outwards. According to this feature and the rupture of the bottom of the fourth segment of the upper Cretaceous Nenjiang Group, the fault can be divided into three segments, e.g. Daliba Village-Gaizijing-Guyang segment, Guyang-Shenjingzi-Julongshan Village segment and Julongshan Village-Caiyuanzi segment. (3) The yellow silt layer at the base of the upper Pleistocene series ((33.66±3.27) ka BP~50ka BP) is offset by the Gudian Fault, while the upper tawny silt layer is not influenced by the fault. Thus, the fault belongs to late Pleistocene active fault. (4) The amount of geomorphic deformation around Shenjingzi is 9m. The depth of the bottom of the upper Pleistocene series is 11m and the Huangshan Group of the mid Pleistocene series exposes to the southeast of the deformation zone. Therefore, the throw of the bottom of the upper Pleistocene series is about 20m at the sides of the deformation zone. In addition, the Qianguo M6(3/4) earthquake occurred in Songyuan area in 1119 AD. Though some studies have been done, arguments still exist on the seismogenic structure of the Qianguo M6(3/4) earthquake. Combined with others studies, Gudian Fault is considered as the seismogenic structure of the Qianguo M6(3/4) earthquake.     

1755年中国东部极端雨涝事件研究

1755年（清乾隆二十年）我国东部大范围、多流域严重雨涝,其后1756、1757年黄河中下游雨涝,连续2年呈现较少见的北涝南旱降水分布格局,这是小冰期中相对温暖时段气候背景下的重大气象灾害和极端气候事件。依据历史文献记载复原多雨的天气实况和气候特征,绘制各年多雨、水灾和伴生的饥荒、虫灾、疫疾的发生地域实况图。结果表明,1755年黄河、长江中下游和淮河流域持续多雨,其中黄淮地区连续雨日超过40 d。有早梅雨,长江下游的梅雨期长达43 d,是18世纪最长的梅雨期,南京的年降水量达1378 mm,是18世纪的最高值。1755年气温偏低,夏寒、秋霜早、冬季寒冷等特征与典型的极端多雨年1823和1954年相同,这3例极端多雨年都是太阳活动周的极小年。