地球极区电离层对行星际激波的响应

本文就地球电离层对行星际激波的动力学响应进行三维全球数值模拟研究．背景行星际磁场为螺旋场,南北分量为零;初始电离层由Ⅰ区场向电流和相应的晨昏电场所主导;行星际激波沿日地连线方向撞击地球．模拟结果表明,在激波的作用下,电离层Ⅰ区电流系统向子夜方向运动,在向阳侧相继出现与原Ⅰ区电流反向的异常场向电流对和同向的新生Ⅰ区电流对．该异常场向电流对在极盖区形成瞬间昏晨电场,尾随原Ⅰ区电流向夜侧方向漂移直至湮没．与此同时,新生的Ⅰ区电流不断增强并向夜侧和赤道方向延伸,最终取代原Ⅰ区电流,相应极盖区又恢复到原来的晨昏电场状态．这一响应过程和行星际激波强度有关：激波强度越强,新生的Ⅰ区场向电流也越强,它向赤道方向延伸的距离也越大,能到达的纬度也越低．上述结果在趋势上与观测到的输运对流涡旋和亚极光块的运动特征一致．     

How Donald V. Helmberger inspired me

I first met Don Helmberger when I visited Caltech in the spring of 1984 as a prospective graduate student.During that visit,I was immediately impressed by Don's...     

INDUCED POLARIZATION RESPONSE OF A POLARIZABLE INHOMOGENEOUS SPHERE *

Expressions for the I. P. activity coefficient for an inhomogeneous sphere with the conductivity increasing/decreasing from the core towards the periphery according to a power law have been derived. In certain geometrical situations of the electrode configurations a negative I. P. signal is obtained. The negative I. P. may be understood as due to modifications in the discharge current from the polarized medium during the discharge process. The results of the investigation may be useful for more accurate interpretation of I. P. anomalies due to isometric inhomogeneous bodies.     

模拟水氡异常判别

阐述了模拟水氡测值的影响因素,并以福州乌鸦嘴泉点为例阐述了模拟水氡异常的判识方法,为模拟水氡的异常判识提供了实例。对模拟水氡异常进行判别,充分了解水点的基本情况及所有影响因素,并了解这些影响因素对水氡的影响规律,在此基础上对干扰因素加以排除,同时用同一水点其他测项的同步变化特征来佐证该异常不是观测过程中人为及仪器因素造成的,最后进行区域背景场对比分析,再用同一区域其他水点同测项测值的同步变化情况加以佐证,以判断是否是该区域应力场所致。分析结果表明,乌鸦嘴泉出现水氡年动态畸变异常的成因在很大程度上可能是区域应力场发生变化所致。     

EM COUPLING IN MULTIFREQUENCY IP AND A GENERALIZATION OF THE COLE-COLE IMPEDANCE MODEL*

The Cole-Cole relaxation model has been found to provide good fits to multifrequency IP data and is derivable mathematically from a reasonable, albeit greatly simplified, physical model of conduction in porous rocks. However, the Cole-Cole model is used to represent the mutual impedance due to inductive or electromagnetic coupling on an empirical basis: this use has not been similarly justified by derivation from any simple physical representation of, say, a half-space, layered or uniform. A uniform conductive half-space can be represented as a simple subsurface loop with particular resistive and inductive properties. Based upon this, a mathematical expression for the mutual impedance between the two pairs of electrodes of a dipole-dipole array is derived and designated “model I”. It is seen that a degenerate case of model I is the Cole-Cole model with frequency exponent c= 1. Model I is thus more general than the Cole-Cole expression and must provide at least as good a fit to a set of field data. Provision for variation of c from unity could be made in model I equally well as for the Cole-Cole model although, at present, this would be a purely empirical alteration. Model I contains four parameters, one of which is, in effect, the resistivity of the half-space. Therefore only three parameters are involved in the model I expressions for normalized amplitude and for phase of the EM-coupling mutual impedance. Model I is compared with previously published “standard” values for two different dipole separations. Under particular constraints, model I is shown to provide better fits than the Cole-Cole model (with c= 1) over particular frequency ranges, specifically at very low frequencies and at moderately high frequencies where the model I phase curve follows the standard phase curve across the axis to positive values (negative coupling).     

Anthropogenic iodine-129 in seawater along a transect from the Norwegian coastal current to the North Pole

Variation in the concentrations of iodine-129 (129I, T1/2=15.7 Myr), a low-level radioactive component of nuclear fuel waste, is documented in surface waters and depth profiles collected during 2001 along a transect from the Norwegian Coastal Current to the North Pole. The surface waters near the Norwegian coast are found to have 20 times higher 129I concentration than the surface waters of the Arctic Ocean. The depth profiles of 129I taken in the Arctic Ocean reveal a sharp decline in the concentration to a depth of about 300-500 m followed by a weaker gradient extending down to the bottom. A twofold increase in the 129I concentration is observed in the upper 1000 m since 1996. Based on known estimates of marine transient time from the release sources (the nuclear reprocessing facilities at La Hague, France, and Sellafield, UK), a doubling in the 129I inventory of the top 1000 m of the Arctic Ocean is expected to occur between the years 2001 and 2006. As 129I of polar mixed layer and Atlantic layer of the Arctic Ocean is ventilated by the East Greenland Current into the Nordic Seas and North Atlantic Ocean, further dispersal and increase of the isotope concentration in these regions will be encountered in the near future.     

ADDRESS ON THE OCCASION OF THE INAUGURATION OF WORLD ASSOCIATION FOR SEDIMENTATION AND EROSION RESEARCH (WASER)

It was a great honour and privilege to be elected President of WASER during the first Council meeting, held in Beijing last Saturday. I hope that I will be able to fulfil the expectations of those that elected me and I look forward to serving the Association and promoting its development. As a hydrologist/geomorphologist who started working in the field of erosion and sedimentation some 35 years ago, I have long appreciated the need for, and importance of, interaction with those with simi…     

肺结核好发部位上肺癌与结核瘤的CT影像研究

目的:探讨肺结核好发部位上周围型肺癌与结核瘤的CT征象及鉴别诊断依据。方法:搜集近6年来有结节或肿块发生在肺结核好发部位的陈旧性肺结核患者134例,其中合并周围型肺癌80例,继发结核瘤54例,所有病例均有完整CT影像资料,并均经病理证实。将周围型肺癌病例定为Ⅰ组,结核瘤病例定为Ⅱ组。再分别将结节或肿块与陈旧性肺结核灶不在同一肺段而孤立存在的,定为Ⅰa组(49例)和Ⅱa组(39例);两者在同一肺段上混合存在的,定为Ⅰb组(31例)和Ⅱb组(15例)。回顾性分析各组的CT征象,对Ⅰ组和Ⅱ组数据组间及组内CT征象分别进行χ²检验并分析。结果:Ⅰ组患者中腺癌比例最高(61/80)。Ⅰ组与Ⅱ组病灶发生部位比较,差异无统计学意义(P＞0.05)。Ⅰa组与Ⅱa组对比,病灶大小≥3cm、密度不均匀、空泡征、浅分叶征,强化≥20Hu及不均匀强化以Ⅰa组多见(P＜0.05);密度均匀、钙化、边缘清楚、强化＜20Hu及环形强化以Ⅱa组多见(P＜0.05)。Ⅰb组与Ⅱb组对比,病灶大小≥3cm、密度不均匀、强化≥20Hu、不均匀强化及合并肺气肿以Ⅰb组多见(P＜0.05);密度均匀及强化＜20Hu以Ⅱb组多见(P＜0.05)。Ⅰa组与Ⅰb组对比,空洞及强化＜20Hu以Ⅰa组多见(P＜0.05);钙化、强化≥20Hu、不均匀强化及合并肺气肿以Ⅰb组多见(P＜0.05);Ⅱa组与Ⅱb组CT征象对比差异无统计学意义(P＞0.05)。结论:陈旧性肺结核患者合并周围型肺癌与继发结核瘤CT征象多有重叠,对各种CT征象综合分析是鉴别诊断的重要依据。     

Recollections of my mentor,Donald V. Helmberger

I arrived at Caltech as a graduate student in the summer of 1979.With a BSc degree in physics,I knew little to nothing about seismology or geophysics.The Seismo...     

A grand master of seismology and mentoring

I joined Don Helmberger's group in the summer of 2008,after getting a Master's degree in China from Sidao Ni,another graduate student of Don's.I was very excite...     

Principle and application of high density spatial sampling in seismic migration

To avoid spatial aliasing problems in broad band high resolution seismic sections, I present a high density migration processing solution. I first analyze the spatial aliasing definition for stack and migration seismic sections and point out the differences between the two. We recognize that migration sections more often show spatial aliasing than stacked sections. Second, from wave propagation theory, I know that migration output is a new spatial sampling process and seismic prestack time migration can provide the high density sampling to prevent spatial aliasing on high resolution migration sections. Using a 2D seismic forward modeling analysis, I have found that seismic spatial aliasing noise can be eliminated by high density spatial sampling in prestack migration. In a 3D seismic data study for Daqing Oilfield in the Songliao Basin, I have also found that seismic sections obtained by high-density spatial sampling (10 × 10 m) in prestack migration have less spatial aliasing noise than those obtained by conventional low density spatial sampling (20 × 40 m) in prestack migration.     

基于低剂量胸部CT原始数据迭代重建增强等级评价不同类型肺小结节的初步分析

目的：探讨低剂量胸部CT（LDCT）原始数据迭代重建（SAFIRE）增强等级与不同类型（实性、部分实性及纯磨玻璃）肺小结节优化显示的对应关系。材料与方法：分析2020年9月至2021年1月行LDCT并符合肺小结节入组标准受试者101例105个肺小结节,依结节性质分为实性结节组（n=27）,部分实性结节组（n=37）和纯磨玻璃结节组（n=41）。采用单因素方差分析、卡方检验或Kruskal-Wallis H检验先分析组间一般资料,再以滤波反投影算法（FBP,B50f）为参照,比较SAFIRE I50f和I70f（分别1~5级）各模式下客观图像质量（噪声值、肺小结节CT值、SNR和CNR）和主观图像质量评分。结果：①三组在性别、身体质量指数和结节分布无显著差异,纯磨玻璃结节组年龄和结节长径均小于实性和部分实性结节组;② SAFIRE I50f 1~5和I70f-5图像噪声值均低于FBP B50f,其中SAFIRE I50f-5噪声值最低,不同模式下肺小结节CT值无显著差异,SAFIRE I50f-5肺小结节SNR和CNR均高于FBP B50f和其他SAFIRE模式;③ SAFIRE I50f 3~5实性和部分实性肺小结节图像质量主观评分高于FBP B50f和除I70f-5外SAFIRE其他模式,SAFIRE I50f-4纯磨玻璃肺小结节图像质量主观评分高于FBP B50f和除I50f-3、I50f-5外SAFIRE其他模式且组间评分无显著差异。结论：SAFIRE I50f-4在LDCT实性、部分实性和纯磨玻璃肺小结节图像质量客观、主观评价方面均表现良好且均衡,可适用于各类型肺小结节LDCT评价。     

A quantitative structure–activity relationships (QSAR) analysis of triarylmethane dye tracers

Dyes are important hydrological tracers. Many different dyes have been proposed as optimal tracers, but none of these dyes can be considered an ideal water tracer. Some dyes are toxic and most sorb to subsurface materials. The objective of this study was to find the molecular structure of an optimal water tracer. We used QSAR to screen a large number of hypothetical molecules, belonging to the class of triarylmethane dyes, in regard to their sorption characteristics to a sandy soil. The QSAR model was based on experimental sorption data obtained from four triarylmethane dyes: C.I. Food Blue 2 (C.I. 42090; Brilliant Blue FCF), C.I. Food Green 3 (C.I. 42053; FD&C Green No. 3), C.I. Acid Blue 7 (C.I. 42080; ORCOacid Blue A 150%), and C.I. Acid Green 9 (C.I. 42100; ORCOacid Fast Green B). Sorption characteristics of the dyes to the sandy soil were expressed with the Langmuir isotherm. Our premise was that dye sorption can be reduced by attachment of sulfonic acid (SO₃) groups to the triarylmethane template. About 70 hypothetical dyes were created and QSAR were used to estimate sorption characteristics. The results indicated that both the position and the number of SO₃ groups affected dye sorption. Sorption decreased with increasing number of SO₃ groups attached to the molecule. Increasing the number of sulfonic acid groups also decreases the toxicity of the compounds. An optimal triarylmethane water tracer contains 4 to 6 SO₃ groups.     

Spectral assessment of isostatic gravity models against CHAMP,GRACE, GOCE satellite-only and combined gravity models

The availability of digital elevation databases representing the topographic and bathymetric relief with global homogeneous coverage and increasing resolution permits the computation of crust-related Earth gravity models, the so-called topographic/isostatic Earth gravity models (henceforth T/I models). Although expressing the spherical harmonic content of the topographic masses, the interpretation purpose of T/I models has not been given the attention it deserves, apart from the fact that they express some degree of compensation to the observed spectrum of the topographic heights, depending on the kind of the applied compensation mechanism. The present contribution attempts to improve the interpretation aspects of T/I Earth gravity models. To this end, a rigorous spectral assessment is performed to a standard Airy/Heiskanen T/I model against different CHAllenging Minisatellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), Gravity field and steadystate Ocean Circulation Explorer (GOCE) satellite-only, and combined gravity models. Different correlation bandwidths emerge for these four groups of satellite-based gravity models. The band-limited forward computation of the models using these bandwidths reproduces nicely the main features of the applied T/I model.     

Evaluation of rainfall-runoff performance using the stochastic integral equation method

The stochastic integral equation method (S.I.E.M.) is used to evaluate the relative performance of a set of both calibrated and uncalibrated rainfall-runoff models with respect to prediction errors. The S.I.E.M. is also used to estimate confidence (prediction) interval values of a runoff criterion variable, given a prescribed rainfall-runoff model, and a similarity measure used to condition the storms that are utilized for model calibration purposes.Because of the increasing attention given to the issue of uncertainty in rainfall-runoff modeling estimates, the S.I.E.M. provides a promising tool for the hydrologist to consider in both research and design.     

Thallium (I) distribution in the Dubossari Reservoir of the Dniester River

Thallium (I) distribution in the Dubossari Reservoir of the Dniester River is studied. The method of inverse voltammetry is used to measure thallium (I) concentration in the water, bottom sediments, and some higher aquatic plants. In the central part of the reservoir, (where a large the Rezina-Rybnitsa Industrial Complex, producing cement and steel, is located), the concentration of thallium (I) in the investigated objects is maximum. The input of thallium (I) from the atmosphere and contaminated soil is assessed by means of measuring its concentration in Xanthoria parietina lichen and in the phytosuspension settled onto clasping-leaved pondweed (Potamogeton perfoliatus).     

Evaluation of rainfall-runoff performance using the stochastic integral equation method

The stochastic integral equation method (S.I.E.M.) is used to evaluate the relative performance of a set of both calibrated and uncalibrated rainfall-runoff models with respect to prediction errors. The S.I.E.M. is also used to estimate confidence (prediction) interval values of a runoff criterion variable, given a prescribed rainfall-runoff model, and a similarity measure used to condition the storms that are utilized for model calibration purposes.Because of the increasing attention given to the issue of uncertainty in rainfall-runoff modeling estimates, the S.I.E.M. provides a promising tool for the hydrologist to consider in both research and design.     

Origin and evolution of waters in the Hancheng coal seams, the Ordos Basin, as revealed from water chemistry and isotope (H, O, 129I) analyses

The coal seams in the Permian Taiyuan Formation and the Carboniferous Shanxi Formation are the primary reservoirs for the coalbed methane(CBM)in the Hancheng region in the Ordos Basin.In this paper,the origin and evolution of waters associated with CBM production were studied on the basis of water chemistry and isotopes including the chloride and iodine compositions,oxygen and hydrogen stable isotopes,and radioactive isotope ratio of129I/127I.The ratio of129I/127I of water was determined by accelerator mass spectrometry(AMS).The result shows that the formation water is of NaHCO3and NaCl types with the total dissolved solids(TDS)varying from 1532.29 mg/L to 7061.12 mg/L.The values of129I and I/Cl ratio indicate that the formation waters were diluted by meteoric water.The129I/127I ratios range from 6.6×10 13to 1459.5×10 13.The129I/127I ratios for most of the samples are between the129I/127I initial value and that of recent anthropogenic water.This age of the formation water samples,obtained through the129I decay curve method,ranges from 0 Ma to 18.5 Ma,suggesting that the waters from the Taiyuan Formation and the Shanxi Formation are very young.Two different origins of water are identified in the Hancheng region.One group is dominated by pre-anthropogenic meteoric water,and is characterized by129I/127I ratios lower than the initial value of 15×10 13andδD,δ18O values of waters below the Global Meteoric Water Line.The other group is characterized by129I/127I ratios in excess of 15×10 13,which has undergone variable degrees of dilution by recent anthropogenic water.     

星载微波ERS-1和多通道SSM/I观测海洋的相关性和随机粗糙面复合模型的数值模拟

欧洲遥感卫星（ERS）和美国防卫气象卫星计划（DMSP）空对地微波遥感是当今研究全球大气地表微波散射辐射和反演地球物理与水文参数的主要数据来源．本文研究了ERS－1散射计和SSM／I多通道辐射计在中国海域观测到的后向散射和热辐射数据,论证了同一地区同一时间段内ERS主动散射计和SSM／I被动辐射计观测数据的相关性．用海域主、被动遥感数据的比较,阐述了主、被动联合多通道分析方法有利于监视和分析复杂地表和海面在时间和空间尺度上的变化．用带泡沫散射层的双尺度随机粗糙面的复合模型计算后向散射和热发射,用以数值模拟ERS和SSM／I数据．并讨论了后向散射与热辐射数值模拟结果的相关性,以及与星载微波遥感器实际观测结果的比较．     

中国的地震烈度衰减率分区

本文采用1900年至1980年发生在中国的198个地震的等震线图,用公式 lnIi/I0=a——blnRi——cRi计算了烈度随距离的衰减率。式中I0为震中烈度,Ri为某烈度Ii等震线昕围面积的等效半径。按上式结果可将中国分成12个区,对于等震线明显受构造控制的地区,用上式分别计算了沿等震线长、短轴方向上不同的衰减率。在近场区,采用了一个与深度有关的修正量（深度因子）D,将上式改写为 ln（Ii/I0）=a——bln（Ri+D）——cRi得出了更适用的结果。对所得的分区结果和上两式中各量的意义进行了某些研究。