大气（气候）系统可预报性问题的讨论

讨论了大气（气候）系统可预报性问题,并指出:1.线性系统、一维自治动力系统、二维自治动力系统和部分可化为二维自治动力系统的一维非自治动力系统是可以进行数值预报的,其预测结果要比统计方法更为科学。而对浑沌动力系统的预报,统计方法则比动力方法更为严谨。2.非浑沌动力系统或浑沌动力系统在非浑沌区的演化行为客观上存在着可预报期限。     

读者·编者·作者专栏

新疆一读者来信问:现在有不少文章讨论“浑沌论”在地震预报中的应用问题,什么是“浑沌论”?有的文章称之为“紊乱论”或者“复杂学”,并断言“这是对经典牛顿力学的否定”等等。我们有些糊涂,请帮助解答。关于浑沌论,是研究复杂事物或复杂过程的一种新的认识论和方法论。因为这种复杂事物往往具有简单线性方程所无法表征的无序或无规性质,因而常与描述复杂图象的分维或分形概念。或者常与表示无序程度的熵等概念有一定联系。但是,不能也不应籍此简单地把浑     

门限自回归模型在地震预报中的应用初探

本文简要介绍了应用门限自回归方法处理浑沌时间序列,建立了浑沌时间序列自回归预报模型,并用其进行外推预报的基本方法及步骤。作者运用该方法建立了云南及滇西、滇东和滇西南等三个片区的半年最大震级序列的震级预报模型。由此预测了1991年上半年模型相应地区可能发生的最大地震震级。     

地震很可能不能预报

康乃尔(Comell)大学的两个地质学家所作的一项实验表明:地震断层显现一种浑沌状态,地震本来就不能预报.科学家们用计算模型模拟相互联接的地震断层,发现了他们认为有关该断层系处于“确定的浑沌状态”(deterministic chaos)的有价值的证据.他们的模型由一对模拟块体组成,块体间是弹性联接,可在一个平面上滑动,且可以被与其弹性相联的第三个驱     

孕震物理过程探索

本文根据非线性科学观点，从多分形、自组织临界现象和浑沌动力学等三个方面综述了地震孕育过程的动力学演化特征及其系统的不稳定性问题。     

走出浑沌——为地震预测预报开绿灯

正引言30年前,梅世蓉先生作为中国科学家代表团成员访问美国归来后,曾打电话问我什么是浑沌?为什么美国科学家开口闭口就是Chaos?这说明,那时对地震预报问题,中美地震学界已在科学的认知上有了显著不同和差距。虽然如此,地震预报发展到今天,国际上对地震问题仍被浑沌(Chaos)所困扰尚未能走出来;而在我国今日不仅如是,更在地震能否预报,应否直面社会的问题上,已不像20世纪六、七十年代那样一路绿灯积极推     

孕震动力系统的研究趋势与展望

该文综述了近年来应用浑沌动力学研究固化介质中裂纹的传播问题，描述了地震发生的动力学模拟，探讨了利用时间序列的相空间重构问题，最后对这些问题进行了简略的讨论。     

蕴震系统前兆场的浑沌吸引子及其分维

简述了蕴震系统前兆场时空演化的浑沌吸引子及其前兆时空分布的分维,并发展了由单个时间序列重建复杂系统动力学的计算方法.探讨了前兆分布在大震前的降维现象.文章着重给出了对由大区域构造网络组成的蕴震系统中多台或多手段组成的多个时间序列数据组建复杂系统动力学的时空综合方法.它对系统的自组织行为给出了更全面、更准确的描述,剔除了单台或单手段的不确定性和随机性.实际计算了京-津-唐地区前兆场演化的浑沌吸引子和前兆时空分布的分维及其在大震前的变化趋势.      

地震预测研究中引入系统科学的几个问题的讨论

随着对复杂事物认识的不断深入，系统科学被引入地震科学研究中。本文 郑重讨论了浑沌论、协同学、耗散结构理论和突变论等理论在研究地震问题中的相互关系，并从认识论的角度探讨了一些问题，以期有益于有关研究。     

非线性科学方法在地震学中的应用专辑

地震科学联合基金会自1984年成立以来,已先后资助非线性科学方法应用于地震预报研究的科研课题28项,其内容广泛涉及系统科学方法论、分形几何学、耗散结构理论、突变论、协同学、浑沌理论、灰色预测理论等。这些课题的研究工作已经获得一批出色的成果,有些已经在地震预报实用化攻关中获得应用成效,其应用发展前景已经引起了广泛的关注。为开拓地震预报的新理论、新思路,发展实用性的地震预报新方法,本期选登了地震科学联合基金会办公室于1990     

THEORETICAL APPROACH TO THE SOLUTION OF THE INFILTRATION PROBLEM

ABSTRACT

The one-dimensional transient downward entry of water in unsaturated soils is investigated theoretically. The mathematical equation describing the infiltration process is derived by combining Darcy's dynamic equation of motion with the continuity and thermodynamic state equations adjusted for the unsaturated flow conditions. The resulting equation together with the corresponding initial and boundary conditions constitues a mathematical initial boundary value problem requiring the solution of a nonlinear partial differential equation of the parabolic type. The volumetric water content is taken as the dependent variable and the time and the position along the vertical direction are taken as the independent variables. The governing equation is of such nature that a solution exists for t > 0 and is uniquely determined if two relationships are defined, together with the specified state of the system, at the initial time t = 0 and at the two boundaries. The two required relations are those of pressure versus permeability and pressure versus volumetric water content.

Since the partial differential equation has strong non-linear terms, a discrete solution is obtained by approximating the derivatives with finite-differences at discrete mesh points in the solution domain and integrated for the corresponding initial and boundary conditions. The use of an implicit difference scheme is employed in order to generate a system of simultaneous non-linear equations that has to be solved for each time increment. For n mesh points the two boundary conditions provide two equations and the repetition of the recurrence formula provides n—2 equations, the total being n equations for each time increment. The solution of the system is obtained by matrix inversion and particularly with a back-substitution technique. The FORTRAN statements used for obtaining the solution with an electronic digital computer (IBM 704) are presented together with the input data.

Analysis of the errors involved in the numerical solution is made and the stability and convergence of the solution of the approximate difference equation to that of the differential equation is investigated. The method applied is that of making a Fourier series expansion of a whole line of errors and then following the progress of the general term of the series expansion and also the behavior of each constituent harmonic. The errors (forming a continuous function of points in an abstract Banach space) are represented by vectors with the Fourier coefficients constituting a second Banach space. The amplification factor of the difference equation is shown to be always less than unity which guarantees the stability of the employed implicit recurrence scheme.

Experiments conducted on a vertical column packed uniformly with very fine sand, show a satisfactory agreement between the theoretically and experimentally obtained values. Many experimental results are shown in an attempt to explain the infiltration phenomenon with emphasis on the shape and movement of the wet front, and the effects of the degree of compaction, initial water content and deaired water on the infiltration rate.     

Solute concentrations in the lower niger river and the source rock contribution

Water quality analyses for the Niger River for the 1980/81 hydrological year are presented. The samples were collected from the main river at Lokoja, and from two main tributaries, the Kaduna and the Benue Rivers. Different water types were distinguished by the concentrations of major ions. The type Ca > Na > Mg > K - HCO₃ > SO₄ > Cl was represented at all stations during at least part of the year. Chloride was found to dominate the sulphate ion in the Kaduna and Niger, while the Benue maintained a higher concentration of sulphate relative to chloride all year round. Distinct patterns of seasonal variation in the ion concentrations were observed, particularly for the samples collected at Lokoja. Low ion concentrations were prominent during periods of high discharge, while low flow periods coincided with high dissolved ion concentrations. The contribution of rainwater to the total dissolved solids in the river waters was assessed indirectly using rainwater chemistry data from the Gulf of Guinea. The estimated rainwater contribution to the Lower Niger amounts to 5.15 mg 1^?1. Geochemical weathering calculations involving reactions of the four major minerals of granitic rocks - anorthite, biotite, albite, and K-feldspar - with carbon dioxide and water, can account for the average water composition of the Lower Niger. The proportion of the ionic components was also related to the occurrence of the respective element in the minerals.     

完善医学影像设备的管理

随着我国医疗保险制度的全面实施和逐步完善和医疗保障体制改革的深入开展,我国医疗卫生行业必将引进社会主义经济体制下的宏观调控和市场竞争机制,这无疑有利于我国卫生事业的健康发展。面对当今科技进步与医院建设的新形势,对开展医院医疗仪器设备的管理提出了挑战。为此,本文探讨了在医院中,医学影像设备管理的几个问题和解决的方案。     

Trophieindikation in Fließgewässern mit Hilfe des TIM (Trophie‐Index Makrophyten) – Erprobung eines neu entwickelten Index im Inninger Bach

Indicating the Trophic State of Running Waters by Using TIM (Trophic Index of Macrophytes) – Exemplary Implementation of a New Index in the River Inninger Bach The river Inninger Bach represents the outflow of the lake Wörthsee (Bavaria). The mean pH of the calcareous river has a value of ca. 8 during the vegetation period, the mean conductivity is about 350 to 400 μS/cm. The macrophyte vegetation of the river course was mapped and the nutrient concentrations of both the water body and the sediment were measured. In every mapping section the Trophic Index of Macrophytes (TIM) was calculated. By cluster analysis the mapping sections were grouped into three zones which differed in macrophyte vegetation. These differences are not associated with varying nutrient concentrations but are mainly due to differences in the degree of shading. In spite of the characterisation of the lake Wörthsee as oligo‐mesotrophic the river Inninger Bach, which represents the outflow of the lake Wörthsee, is classified as meso‐eutrophic by the Trophic Index of Macrophytes TIM. The increased trophic state of the river compared to the lake is caused by the river Krebsbach, a small tributary flowing into the river Inninger Bach only a short stretch downstream of its outflow of the lake Wörthsee. The river Krebsbach shows a total phosphorus concentration of about 56 μg/L P. The input of diaspores of submerged macrophytes both from the oligo‐mesotrophic lake Wörthsee and the eutrophic river Krebsbach leads to a submerged vegetation comprising species with different optima in regard to the trophic situation. This is one of the main reasons why many values of the TIM have to be labeled as “not sure”.     

Scenario predictions for potential near-field and far-field earthquakes affecting Hong Kong

Historical earthquakes noted in the written records of the South China region, including Hong Kong, are not well delineated along identified prominent fault sources. Despite the lack of any definitive, localised trend in the spatial distribution of seismic activity in the region, there does appear to be some major disparity in the seismic activity rates (especially for large magnitude earthquakes) between the near-field and the far-field regions of Hong Kong. Despite this observation, previous studies of the regional seismic activity and seismic ground motion hazard (the latter using a probabilistic seismic hazard assessment, PSHA) have considered very broad source zone regions, in which uniform levels of seismic activity have been assumed. The present paper further scrutinises this broad source zone (BSZ) approach by adopting a novel expanding circular disc (ECD) method to determine the rates of earthquake recurrence. Such a method is intended to counter-check previously developed models by determining earthquake scenario events in terms of magnitude–distance (M–R) pairs or combinations, having defined values of average return period. Unlike the BSZ approach, the ECD method specifically accounts for the supposed variations in the seismic activity rates between events in the near-field and the far-field of Hong Kong.The form of the developed method is particularly suited to the determination of design-level earthquake ground motions for bedrock sites, since it assumes a directionally-independent attenuation model as described in the companion paper. It is found that, whilst the BSZ approach may indicate the overall average levels of hazard that are representative of the South China region as a whole, it does not capture the large disparity in seismic activity rates between near-field and far-field events. This important feature is expected to have a significant impact upon engineering assessments of the seismic safety of structures in Hong Kong and elsewhere in the South China region. For example, it is found that for events with M≥6, the seismic activity rate (normalised by time and area) in the very far-field is around 3.5 times larger than in the near-field and medium-field of Hong Kong. The resulting design M-R combinations, covering a range of return periods from 70 to 2500 years, are limited, for very long return periods and for distant events, by the maximum credible earthquake (MCE) magnitude. Intensive research to determine this seismic hazard parameter is recommended, in order to refine further the results of the ECD analysis, which presently conservatively assumes the MCE to range between M=6 in the near-field of Hong Kong to M=8 in the very far-field, at distances greater than 280 km from Hong Kong.     

Jurassic accretion tectonics of Japan

Abstract The Jurassic accretionary complex and coeval granites in Japan represent remnants of the Jurassic arc-trench system developed between the Asian continent and Pacific Ocean. The Jurassic accretionary complex occurs as a large-scale nappe that is tectonically sandwiched between the overlying pre-Jurassic nappes and underlying post-Jurassic nappes. By virtue of new research styles (microfossil mapping and chronometric mapping) the following new views of the Jurassic accretionary complex in Japan, that suggest those for on-land exposed ancient accretionary complexes in general, have been obtained: (i) the accretion age of the Jurassic accretionary complex ranges over ～ 80 million years from the latest Triassic to earliest Cretaceous according to a reconstructed stratigraphy of component rocks (oceanic plate stratigraphy); (ii) the accretionary complex is subdivided into several nappe units, each characterized by unique oceanic plate stratigraphy; (iii) a tectonically downward-younging polarity is observed in the piled nappes; (iv) the Jurassic accretionary complex is composed of coherent-type and chaotic-type units, the former retaining the primary accretionary structures while the latter are characterized by collapsed and secondarily mixed materialslfabrics derived from the former; (v) the chaotic-type units predominate in volume over the coherent-type units; (vi) the accretionary complex suffered from a regional low-grade metamorphism (up to the lower greenschist facies) within ～10–20 million years after the accretion timing; and (vii) the lateral extent of the Jurassic accretionary complex in East Asia is intermittently traced from the Koryak mountains in Russia to North Palawan in the west Philippines for ～6000 km. Discussion focuses on (i) the low preservation ratio of the coherent-type units to the chaotic-type units with respect to frequent subduction erosion by seamount subduction; (ii) absence of the Franciscan-type melange, suggesting sedimentary mixing origin for the chaotic-type unit; (iii) a growth rate of the Jurassic accretionary complex compatible to modern analogues; and (iv) the total volume of the Jurassic accretionary complex in Japan with respect to the most likely terrigeiious elastics source along the 250 Ma continent-continent collision suture in central China (between the Sino-Korean and Yangtze blocks).     

Analysis of the natural remanent magnetization of rocks by measuring the efficiency ratio through alternating field demagnetization spectra

The REM(AF) method is a new tool for the analysis of the origin and alternating field demagnetization coercivity spectra of the remanent magnetization. We applied this method on precambrian Gila diabase sheets from Arizona in order to identify the high coercivity magnetic carrier, and on artificially shocked Rowley Regis basalt from UK in order to analyze the effect of the shock on the natural remanent magnetization. In the Gila diabase the high coercivity magnetic component was identified to be most likely represented by the acicular magnetite (increase in the efficiency ratio in the high coercivity region). In the Rowley Regis basalt, the REM(AF) analysis revealed that comparing to NRM, the shock produced a different distribution of the AF demagnetization coercivity spectra due to the occurrence of the Shock Remanent Magnetization.     

Planetary magnetospheres: 1991–1993

This paper briefly summarizes published work in the field of planetary magnetospheres from 1991 to mid-1993. The 1992 Ulysses fly-by and the proximity of Jupiter for remote sensing have meant that the Jovian magnetosphere has dominated interest in the field, resulting in studies of the interaction of magnetospheric plasma with dust grains as well as the satellite Io, the morphology and chemistry of the Io plasma torus, the aurora, plus plasma processes in the middle magnetospheric current sheet and outer magnetosphere. Two debates (about the plasma sources and transport rate and about the degree of symmetry of the magnetic field) have dominated recent work on the magnetosphere of Saturn. The effects of highly asymmetric magnetic fields on magnetospheric configurations and processes have been the major themes of work on the outermost giant planets since Voyager 2 flew past Uranus and Neptune in 1986 and 1989 respectively.     

Prüfstrategie zur Bewertung potentiell erbgutverändernder Wasserinhaltsstoffe unter Einsatz gentoxikologischer Methoden

Assessment and Characterization of Genotoxic Water Contaminants with Modern Genotoxicological Methods The necessity of genotoxicological studies in water requires modern and practicable concepts for a prospective environmental protection. Up to now, genotoxicological studies prefer only the observation and detection of basic genotoxic effects in enriched surface water samples and the fruitless search for the involved water contaminants. In this publication, a new test strategy for the detection and the assessment of genotoxicity in water will be introduced. This strategy allows the detection and the verification of positive results and is therefore able to assess the evidence of these results for the water quality more accurate. The aim of this strategy is the detection of basic genotoxic effects (primary DNA damages), the clarification of the biological mechanisms, and the search for the reasons with modern analytical methods. The involved water contaminants and their mode of action will then be better understood. A test strategy in three steps will be proposed. In the first step genotoxicological indicator tests such as comet assay, alkaline filter elution, or the SOS-umu-test are used to get information about the basic status of the tested water samples. In the second step, the positive results of the primary DNA damages will be verified with mutation tests such as the micronucleus assay. The involved biological mechanisms will be biochemically characterized, and the biological active substances will be preclassified. Finally, in the third step the observed mechanisms will be confirmed with modern chemical methods such as HPLC MS-MS. These modern techniques are also able to detect and quantify the genotoxic compounds preclassified in step two.     

降雨对无支挡结构下隧道-滑坡正交体系的作用机理研究

通过大型地质力学模型试验,研究在无支挡结构下降雨对隧道-滑坡正交体系的作用机理。主要研究不同降雨阶段,隧道-滑坡正交体系下隧道纵向应变的变化特征及隧道不同横断面环向应力变化特点,并重点分析在不同降雨阶段,不同位置及其不同横断面滑体的位移变化特征。试验结果表明:(1)降雨可导致坡体横断面断裂而出现新的滑移面,从而导致坡体失稳。(2)在隧道-滑坡正交体系下,随着雨水的下渗及滑体土样含水率不断增大,隧道局部应变有明显突变,且山侧纵向应变比河侧应变要大。(3)在隧道-滑坡正交体系下,降雨使得隧道环向应力呈不均匀变化:隧道的底部应力大于顶部应力,山侧应力大于河侧应力,表明降雨可导致滑体蠕动或局部滑移,引起隧道不均匀受力及变形,这对隧道结构的安全非常不利。本次试验可为雨水充沛区的滑坡及隧道抗滑设计提供一定参考。