面向绝对重力测量的振动补偿技术发展

绝对重力仪是用于直接测量重力加速度值的精密仪器,可以作为计量标准器对相对重力仪进行定期校准.现有绝对重力仪的测量精度可达微伽(1μGal=1×10-8m/s2)量级,测量精度主要受振动噪声的限制.垂直隔振和振动补偿技术是目前常用的两种处理振动噪声的方法.随着绝对重力仪在野外流动重力观测和海洋/航空重力测量中的应用需求日...     

联合串行式和钟摆式卫星编队精确建立下一代HIP-3S地球重力场模型

第一,基于扰动星间距离观测量对地球重力场反演精度的敏感性优于星间距离观测值的特性,本文构建了新型扰动星间距离法(DIRM).第二,有效检验了下一代HIP-3S编队的轨道稳定性,结果表明:HIP-3S编队较稳定,有利于提高地球重力场反演精度.第三,基于扰动星间距离法,分别利用当前GRACE-2S串行式双星编队和下一代HIP-3S复合式三星编队精确反演了120阶地球重力场,在120阶处累计大地水准面精度为2.271×10~(-1)m和1.923×10~(-3)m,结果表明:HIP-3S复合式三星编队有利于建立下一代高精度和高空间分辨率的地球重力场模型.     

利用超声尾波观测1.5 m长岩石断层黏滑实验的波速变化

在实验室内利用超声尾波观测大尺度(1.5 m)岩石断层的黏滑过程.利用基于尾波干涉的观测方法,我们获得了高达10~(-6)的相对波速变化的观测精度,这相当于~10 kPa的应力变化.利用高精度的测量,我们获取两种不同加载速率下(1μm·s~(-1),10μm·s~(-1))黏滑过程三个阶段(恢复、加载和滑动)基于波速变化的特征量.我们更进一步获取了断层失稳阶段波速变化的时空演化过程.最后讨论了该观测方法需要改进的地方.以上研究结果表明作为一种对现有实验观测手段的有益补充,利用超声尾波观测实验室大尺度岩石断层的动力学过程是可行的.     

利用主动震源直达波互相关时延检测技术监测小江断裂带浅层地震波波速变化

为了监测云南小江断裂带附近地震波波速的连续变化,2006年4月在小江断裂带以西10 km布置了一条长235 m的主动震源浅勘测线,进行为期1个月的连续观测实验。采用前后互相关技术对直达波进行了高精度波速变化测量,分析得到以下结果和结论:(1)实验期间,实验点地下介质存在相对波速变化δv/v≈10-3~10-2;(2)波速变化随震中距增加迅速减小,这可能反映了较浅层波速变化与较深层相比更剧烈;(3)波速变化和大气压变化有很好的相关性,相对波速变化对大气压的敏感系数为10-6Pa-1量级;(4)降雨会显著影响波速与气压的关系,降雨前相对波速变化随气压增加而增加,而降雨后相对波速则与气压呈负相关。     

低频可控震源激发信号特征及高精度动态监测应用

通过实验测试了国产KZ28LF低频可控震源在线性升频、伪随机编码和单频3种激发模式下的信号特征及在地下介质高精度动态监测中的应用效果。结果表明:(1)线性升频和伪随机编码激发模式可稳定激发1.5～12 Hz的低频信号,近场信号互相关系数大于0.95的分别占81%和63%,信号能量在9～12 Hz较强、在1.5～9 Hz较弱,低频外传能量较弱,而单频激发时高次谐波能量较强,信号重复性较差。(2)相干法和反褶积法均能压缩震源子波,恢复介质真实响应,相干法的结果重复性和信噪比最高,反褶积法保幅和保相效果最好。(3)叠加后探测距离可达20 km,波速变化探测精度达10~(-4)。     

金属矿电磁感应法理论和模型实验结果

本文阐明三个问题:(1)从电磁学基本原理出发,导出导电性矿体电磁感应二次场的普遍公式。这公式对任何类型的激发装置和接收装置以及对任何形状的矿体均适用,特別是在低频情况下具有普遍意义。(2)从普遍公式出发,对感应二次场的频率特性和空间特性进行了分析,并用模型实验结果验证了理论。(3)考察了电磁感应法的找矿效果和克服干扰的能力,并与直流电法作了比较,分析了两者的有利方面和不利方面,阐明了在电磁感应法中利用低频和多频以及观测多种要素的必要性。     

基于残余星间速度法精确和快速反演下一代GRACE Follow-On地球重力场

基于新型残余星间速度法(RIRM)反演了120阶GRACE Follow-On地球重力场.第一,由于GPS定轨精度相对较低,通过将激光干涉测距仪的高精度残余星间速度(测量精度10-7 m·s-1)引入残余轨道速度差分矢量的视线分量构建了新型RIRM观测方程.第二,基于2点、4点、6点和8点RIRM公式对比论证了最优的插值点数.如果相关系数和采样间隔一定,随着插值点数的增加,卫星观测值的信号量被有效加强,而卫星观测值的误差量也同时增加.因此,6点RIRM公式是提高下一代地球重力场精度的较优选择.第三,相关系数对地球重力场精度的影响在不同频段表现为不同特性.随着相关系数的逐渐增大,地球长波重力场精度逐渐降低,而地球中长波重力场精度逐渐升高.第四,基于6点RIRM公式,通过30天观测数据和采样间隔5s,分别利用星间速度和残余星间速度观测值,在120阶次处反演下一代GRACE Follow-On累计大地水准面精度为1.638×10-3 m和1.396×10-3 m.研究结果表明:(1)残余星间速度观测量较星间速度对地球重力场反演精度更敏感;(2)GRACE FollowOn地球重力场精度较GRACE至少高10倍.     

高分一号卫星PMS传感器湖南攸县幅数据质量评价

基于高分一号卫星PMS传感器接收的全色(0.45~0.90μm)和蓝(0.45~0.52μm)、绿(0.52~0.59μm)、红(0.63~0.69μm)波段数据,对其进行图像预处理,分别运用IHS变换、Brovey变换、乘积变换、主成分变换、小波变换和GS变换等六种方法进行数据融合,再以321波段组合分别彩色合成影像,结合SPOT5数据,从几何精度、辐射质量两个方面定量分析了该卫星PMS传感器的数据质量.结果表明:1)高分数据采用乘积变换的融合方法进行融合,效果较好;2)高分数据不存在波段错位现象,影像畸变、扭曲现象也极小;3)高分数据的整体辐射精度、波段间相关系数和光谱质量均略差于SPOT5数据,但是高分数据所含噪声较少,信息量较丰富.无论是从辐射精度还是信噪比方面来看,高分数据的1波段最好,3波段所含的信息量最多.     

基于逆重复m序列的岩矿石标本电性参数测量方法研究

岩矿石标本电性参数实验中,常使用一个或者多个频率激励的变频法测量电阻率,存在观测效率低、可用信息少、抗干扰能力弱等实际问题.本文将变频法改进为伪随机电流信号法进行观测,提出激励场源使用逆重复m序列伪随机电流信号的观测方法,推导出抑制工频干扰的参数选取条件,进而针对岩矿石标本电性参数实验中激励场源的特殊要求,详细分析了观测系统中信号产生与接收面临的问题,并给出了解决方法:采用高驱动能力设计及阻抗匹配技术解决岩矿石标本电阻率分布跨度大(n×10ⁿ×10⁶Ωm)导致的发送端驱动能力不足以及接收端阻抗不匹配等问题;采用系统频率响应校正技术修正系统存在的观测误差;采用高频微弱信号产生与拾取的相关技术,保证电流密度处于岩矿石标本的线性响应区间,避免非线性效应,实现宽频率分布范围观测(10-3~10⁴kHz).采用所研发的可编码、高精度、小电流(10^-6A)、连续可调输出的精密电流源,使用阻容模型进行实验测试,结果表明:(1)该方法可在10^-3~10⁴Hz频带内产生90个有效测量频点,可满足频带宽、频点密、压制工频干扰的观测要求;(2)实验中恒流源输出稳定,不同负载下直流输出稳定性误差小于0.5%,精度满足实验中对输出电流的要求;(3)标定后测量误差小于0.5%,系统具有较高的观测精度与抗干扰能力;(4)与变频法相比观测效率提高2.3倍.通过该方法开发的观测装置可有效提高工作效率和抗干扰能力,提高观测数据的准确性,适用于各种类型岩矿石标本电性参数观测工作.     

峰值速度和加速度对环境剪应力的依赖性

从导出的地震定标律和地震破裂过程的断裂力学模式出发,得到了震源平均位移、速度和加速度谱的表达式,进而又推导出震源的峰值位移d_m,速度v_m和加速度a_m的表达式:d_m=k_dM_0~2/~3τ_0~(2/3),v=k_vM_0~(1/3)τ_0~(4/3),a_m=k_aτ_0~2式中M_0是地震矩,τ_0是环境剪应力值,k_d,k_v,k_a为适当的常数.我们选用了66个地震的观测资料,这些地震的矩震级范围包括了从1级左右的极微震,3-5级的小震,直到6-7级的大震;地震矩从10~9-10~(20)Nm,跨越了10个数量级,并用这些地震检验了上述公式. 令所有地震的平均应力为5MPa,定出常数k_d,k_v,k_a,进而由速度和加速度观测资料求得66个地震的环境剪应力τ_0值,这些数值相当稳定.多数极微震的τ_0值在2-4MPa之间;小震的τ_0值多数在4-8MPa左右;大震的τ_0值为10MPa左右。τ_0值对震源深度和断层类型有明显的依赖性.一般深度很浅的小震和极微震,τ_0值很低;正断层地震的τ_0值相对较低;逆断层地震的τ_0值较高;走滑断层地震的τ_0值则居中.     

10,000 Years of explosive eruptions of Merapi Volcano, Central Java: archaeological and modern implications

Stratigraphy and radiocarbon dating of pyroclastic deposits at Merapi Volcano, Central Java, reveals 10,000 years of explosive eruptions. Highlights include:(1) Construction of an Old Merapi stratovolcano to the height of the present cone or slightly higher. Our oldest age for an explosive eruption is 9630±60 ¹⁴C y B.P.; construction of Old Merapi certainly began earlier.(2) Collapse(s) of Old Merapi that left a somma rim high on its eastern slope and sent one or more debris avalanche(s) down its southern and western flanks. Impoundment of Kali Progo to form an early Lake Borobudur at 3400 ¹⁴C y B.P. hints at a possible early collapse of Merapi. The latest somma-forming collapse occurred 1900 ¹⁴C y B.P. The current cone, New Merapi, began to grow soon thereafter.(3) Several large and many small Buddhist and Hindu temples were constructed in Central Java between 732 and 900 A.D. (roughly, 1400–1000 ¹⁴C y B.P.). Explosive Merapi eruptions occurred before, during and after temple construction. Some temples were destroyed and (or) buried soon after their construction, and we suspect that this destruction contributed to an abrupt shift of power and organized society to East Java in 928 A.D. Other temples sites, though, were occupied by “caretakers” for several centuries longer.(4) A partial collapse of New Merapi occurred <1130±50 ¹⁴C y B.P. Eruptions 700–800 ¹⁴C y B.P. (12–14th century A.D.) deposited ash on the floors of (still-occupied?) Candi Sambisari and Candi Kedulan. We speculate but cannot prove that these eruptions were triggered by (the same?) partial collapse of New Merapi, and that the eruptions, in turn, ended “caretaker” occupation at Candi Sambisari and Candi Kedulan. A new or raised Lake Borobudur also existed during part or all of the 12–14th centuries, probably impounded by deposits from Merapi.(5) Relatively benign lava-dome extrusion and dome-collapse pyroclastic flows have dominated activity of the 20th century, but explosive eruptions much larger than any of this century have occurred many times during Merapi's history, most recently during the 19th century.Are the relatively small eruptions of the 20th century a new style of open-vent, less hazardous activity that will persist for the foreseeable future? Or, alternatively, are they merely low-level “background” activity that could be interrupted upon relatively short notice by much larger explosive eruptions? The geologic record suggests the latter, which would place several hundred thousand people at risk. We know of no reliable method to forecast when an explosive eruption will interrupt the present interval of low-level activity. This conclusion has important implications for hazard evaluation.     

Reconstructing Regional Ionospheric Electron Density: A Combined Spherical Slepian Function and Empirical Orthogonal Function Approach

The computerized ionospheric tomography is a method for imaging the Earth’s ionosphere using a sounding technique and computing the slant total electron content (STEC) values from data of the global positioning system (GPS). The most common approach for ionospheric tomography is the voxel-based model, in which (1) the ionosphere is divided into voxels, (2) the STEC is then measured along (many) satellite signal paths, and finally (3) an inversion procedure is applied to reconstruct the electron density distribution of the ionosphere. In this study, a computationally efficient approach is introduced, which improves the inversion procedure of step 3. Our proposed method combines the empirical orthogonal function and the spherical Slepian base functions to describe the vertical and horizontal distribution of electron density, respectively. Thus, it can be applied on regional and global case studies. Numerical application is demonstrated using the ground-based GPS data over South America. Our results are validated against ionospheric tomography obtained from the constellation observing system for meteorology, ionosphere, and climate (COSMIC) observations and the global ionosphere map estimated by international centers, as well as by comparison with STEC derived from independent GPS stations. Using the proposed approach, we find that while using 30 GPS measurements in South America, one can achieve comparable accuracy with those from COSMIC data within the reported accuracy (1 × 10¹¹ el/cm³) of the product. Comparisons with real observations of two GPS stations indicate an absolute difference is less than 2 TECU (where 1 total electron content unit, TECU, is 10¹⁶ electrons/m²).     

Factors controlling stable oxygen,hydrogen and carbon isotope ratios in regional groundwater of the eastern United Arab Emirates (UAE)

Increasing groundwater salinity and depletion of the aquifers are major concerns in the UAE. Isotopes of oxygen, hydrogen, and carbon concentrations in groundwater were used to estimate evaporation loss using the isotopes of oxygen and hydrogen, and using a carbon isotope to trace inorganic carbon cycling in two main aquifers in the eastern part of the United Arab Emirates. The δD‐δ¹⁸O of groundwater samples plotted on a line given by: δD = 4 δ¹⁸O + 4 ·4 (r² = 0·4). In comparison, the local meteoric water line (LMWL) has been defined by the line: δD = 8 δ¹⁸O + 15. In order to better understand the system investigated, samples were separated into two groups based on the δD‐δ¹⁸O relationship. These are (1) samples that plot above the LMWL (δD = 6·1 δ¹⁸O + 12·4, r² = 0·8) and which are located predominantly in the north of the study area, and (2) samples that plot below the LMWL (δD = 5·6 δ¹⁸O + 6·2, r² = 0·8) and which are mostly distributed in the south. Slopes for both the groups are similar and lower than that for LMWL indicating potential evaporation of recharging water. However, the y‐intercept, which differs between the two groups, suggests evaporation of return flow and evapotranspiration in the unsaturated zone to be more significant in the south. This is attributed to intense agricultural activities in the region. Samples from the eastern Gravel Plain aquifer have δ¹³C and dissolved inorganic carbon (DIC) values in the range from ? 10 to 17‰, and 12–100 mg C/l, respectively, while the range for those from the Ophiolite aquifer is from ? 11 to ? 16.4‰, and 16–114 mg C/l respectively. This suggests the control of C‐3 and C‐4 plants on DIC formation, an observation supported by the range δ¹³C of soil organic matter (from ? 18·5 to ? 22·1‰.) Copyright © 2007 John Wiley & Sons, Ltd.     

辽宁省烈度速报算法研究及其在灯塔地震中的检验

立足于辽宁省烈度速报的实际需求,在多种地震烈度算法的研究基础上,结合震害实际,从滤波、场地校正、网格计算、烈度计算、已知震源计算等方面进行探索和试验,提出一种新的实时地震烈度计算的方法,并在辽阳灯塔5.1级地震中得到实际检验。     

Responses of geostationary orbit energetic electron fluxes to chorus waves under different geomagnetic conditions

We investigate the flux evolution of geostationary orbit energetic electrons during a strong storm on 24 August 2005(event A,the storm index Dst<200 nT,the average substorm index AE=436 nT)and a weak storm on 28 October 2006(event B,Dst>50 nT,average AE=320 nT).Data collected by LANL and GOES-12 satellites show that energetic electron fluxes increase by a factor of 10 during the recovery phase compared to the prestorm level for both events A and B.As the substorm continued,the Cluster C4 satellite observed strong whistler-mode chorus waves(with spectral density approaching 10 5nT2/Hz).The wave amplitude correlates with the substorm AE index,but is less correlated with the storm Dst index.Using a Gaussian distribution fitting method,we solve the Fokker-Planck diffusion equation governing the wave-particle interaction.Numerical results demonstrate that chorus waves efficiently accelerate~1 MeV energetic electrons,particularly at high pitch angles.The calculated acceleration time scale and amplitude are comparable to observations.Our results provide new observational support for chorus-driven acceleration of radiation belt energetic electrons.     

培养液更换对萼花臂尾轮虫(Brachionus calyciflorus)休眠卵形成的影响

在种群累积培养状态下研究了培养液更换对萼花臂尾轮虫（ Ｂｒａｃｈｉｏｎｕｓ ｃａｌｙｃｉｆｌｏｒｕｓ）休眠卵形成的影响,结果表明,在培养液不予更换的情况下,萼花臂尾轮虫休眠卵的产量和形成效率分别为 ７２４ ３３３３± ４０． ５２５７ｉｎｄ（６ｄ．２０ｍＬ）－１和 ６ ．０３６１± ０． ３３７７ｉｎｄ（５ × １０６ ｃｅｌｌｓ）－１（ａｌ－ｇａｅ ｄｉｅｔ）与之相比,当培养液每 ２天更换一次时,其休眠卵的产量和形成效率分别下降至６３７．３３３３±１６． ８０２８ｉｎｄ．（６ｄ·２０ｍＬ）－１和５ ．３１１１±０ ．１４００ｉｎｄ（５×１０６ｃｅｌｌｓ）－１（ａｌｇａｅ　ｄｉｅｔ）．随着培养液更换频率增大至每天一次时,其休眠卵的产量和形成效率下降的幅度进一步增大培养液更换对轮虫种群中的混交雌体百分率和混交雌体受精率无显著的影响,最后探讨了培养液更换对萼花臂尾轮虫休眠卵形成影响的机理．     

Hydraulic Tomography: 3D Hydraulic Conductivity,Fracture Network,and Connectivity in Mudstone

We present the first demonstration of hydraulic tomography (HT) to estimate the three-dimensional (3D) hydraulic conductivity (K) distribution of a fractured aquifer at high-resolution field scale (HRFS), including the fracture network and connectivity through it. We invert drawdown data collected from packer-isolated borehole intervals during 42 pumping tests in a wellfield at the former Naval Air Warfare Center, West Trenton, New Jersey, in the Newark Basin. Five additional tests were reserved for a quality check of HT results. We used an equivalent porous medium forward model and geostatistical inversion to estimate 3D K at high resolution (K blocks <1 m³), using no strict assumptions about K variability or fracture statistics. The resulting 3D K estimate ranges from approximately 0.1 (highest-K fractures) to approximately 10⁻¹³ m/s (unfractured mudstone). Important estimated features include: (1) a highly fractured zone (HFZ) consisting of a sequence of high-K bedding-plane fractures; (2) a low-K zone that disrupts the HFZ; (3) several secondary fractures of limited extent; and (4) regions of very low-K rock matrix. The 3D K estimate explains complex drawdown behavior observed in the field. Drawdown tracing and particle tracking simulations reveal a 3D fracture network within the estimated K distribution, and connectivity routes through the network. Model fit is best in the shallower part of the wellfield, with high density of observations and tests. The capabilities of HT demonstrated for 3D fractured aquifer characterization at HRFS may support improved in situ remediation for contaminant source zones, and applications in mining, repository assessment, or geotechnical engineering.     

Gravity field determination using boundary element methods

The Boundary Element Method (BEM), a numerical technique for solving boundary integral equations, is introduced to determine the earth's gravity field. After a short survey on its main principles, we apply this method to the fixed gravimetric boundary value problem (BVP), i.e. the determination of the earth's gravitational potential from measurements of the intensity of the gravity field in points on the earth's surface. We show how to linearize this nonlinear BVP using an implicit function theorem and how to transform the linearized BVP into a boundary integral equation using the single layer representation. A Galerkin method is used to transform the boundary integral equation using the single layer representation. A Galerkin method is used to transform the boundary integral equation into a linear system of equations. We discuss the major problems of this approach for setting up and solving the linear system. The BVP is numerically solved for a bounded part of the earth's surface using a high resolution reference gravity model, measured gravity values of high density, and a 50 50 m² digital terrain model to describe the earth's surface. We obtain a gravity field resolution of 1 1 km² with an accuracy of the order 10^–3 to 10^–4 in about 1 CPU-hour on a Siemens/Fujitsu SIMD vector pipeline machine using highly sophisticated numerical integration techniques and fast equation solvers. We conclude that BEM is a powerful numerical tool for solving boundary value problems and may be an alternative to classical geodetic techniques.     

Experimental Designs Applied to Desorption of Dichromate Ions after Separation and Preconcentration from Natural and Industrial Water by Modified Nano‐Alumina

Nano‐alumina modified by 9‐aminoacridine was used as a sorbent for separation and determination of dichromate ions from water. Statistical method, based on surface response design, has been used for the optimization of dichromate ions elution from 9‐aminoacridine nano‐alumina. The adsorbed dichromate ions were found to be eluted quantitatively with 0.8 mol L^?1 KCl in 1.6 mol L^?1 NaOH which optimized by response surface design. Under optimum conditions, the accuracy, precision (relative standard deviation, RSD%) and R‐square of the method were calculated as >98, <3, and >94%, respectively. Remarkable agreement between experimental and theoretical data was confirmed the predicted assumption. The method was applied to the simultaneous determination of dichromate in natural and industrial water samples. We also examined the retention of dichromate anions in the presence of Cl^?, , and anions at pH 3.     

Reconstruction and analysis of sub-plinian tephra dispersal during the 1530 A.D. Soufrière (Guadeloupe) eruption: Implications for scenario definition and hazards assessment

The last magmatic eruption of Soufrière of Guadeloupe dated at 1530 A.D. (Soufrière eruption) is characterized by an onset with a partial flank-collapse and emplacement of a debris-avalanche that was followed by a sub-plinian VEI 2–3 explosive short-lived eruption (Phase-1) with a column that reached a height between 9 and 12 km producing about 3.9 × 10⁶ m³ DRE (16.3 × 10⁶ m³ bulk) of juvenile products. The column recurrently collapsed generating scoriaceous pyroclastic flows in radiating valleys up to a distance of 5–6 km with a maximum interpolated bulk deposit volume of 11.7 × 10⁶ m³ (5 × 10⁶ m³ DRE). We have used HAZMAP, a numerical simple first-order model of tephra dispersal [Macedonio, G., Costa, A., Longo, A., 2005. A computer model for volcanic ash fallout and assessment of subsequent hazard. Comput. Geosci. 31, 837–845] to reconstruct to a first approximation the potential dispersal of tephra and associated tephra mass loadings generated by the sub-plinian Phase 1 of the 1530 A.D. eruption. We have tested our model on a deterministic average dry season wind profile that best-fits the available data as well as on a set of randomly selected wind profiles over a 5 year interval that allows the elaboration of probabilistic maps for the exceedance of specific tephra mass load thresholds. Results show that in the hypothesis of a future 1530 A.D. scenario, populated areas to a distance of 3–4 km west–southwest of the vent could be subjected to a static load pressure between 2 and 10 kPa in case of wet tephra, susceptible to cause variable degrees of roof damage. Our results provide volcanological input parameters for scenario and event-tree definition, for assessing volcanic risks and evaluating their impact in case of a future sub-plinian eruption which could affect up to 70 000 people in southern Basse-Terre island and the region. They also provide a framework to aid decision-making concerning land management and development. A sub-plinian eruption is the most likely magmatic scenario in case of a future eruption of this volcano which has shown, since 1992, increasing signs of low-energy seismic, thermal, and acid degassing unrest without significant deformation.