Geopolitical codes and popular representations*

Geopolitical codes – intellectual tools for practising statecraft – share a certain basic understanding of the world with less articulate, popular representations. Both are influenced by national geographies and histories. The international power game may (particularly in large countries) temporarily alienate codes from popular representations but the ensuing conflicts also prove the solidity of popular visions about the world order. Change is nevertheless possible and should be one of the central themes of research in geopolitical representations. This article concludes with specifying five perspectives that can be adopted in cross-national research: time/space models of the world, national myths, territorial narratives, active/passive approach of international relations and reactions to international crises.     

国家创新系统研究中地理学的视角*

促进知识经济发展的关键是建立和完善国家创新系统,而创新系统中知识流动的效率是解释国家创新能力高低最重要的指标。高新技术企业和知识的生产和传播者在空间上的集聚现象说明知识的流动是一个空间过程。从创新系统的区域层次性、知识流动的区位效应以及知识创新的区域分工等现象中,可以看到从地理学角度研究国家创新系统的切入点。     

Suitability of Hydrologic Evaluation of Landfill Performance (HELP) model of the US Environmental Protection Agency for the simulation of the water balance of landfill cover systems

 Cover systems are widely used to safeguard landfills and contaminated sites. The evaluation of the water balance is crucial for the design of landfill covers. The Hydrologic Evaluation of Landfill Performance (HELP) model of the US Environmental Protection Agency was developed for this purpose. This paper discusses some limitations of version 2 of this model and some operational difficulties for the use of this model in Germany, which has been developed for the United States. The model results are tested against field data of the water balance, measured on test fields on the Georgswerder landfill in Hamburg. Theoretically, HELP considers gravitational forces as driving forces of water flow only. Therefore capillary barriers cannot be simulated. Furthermore, the formation of and the flow through macropores are not considered, a main critical process that the diminishes the effectiveness of compacted soil liners. In the output comparison, the matching of measured and simulated data is quite good for lateral drainage, but failed for surface runoff and liner leakage through compacted soil liners. A further validation study is planned for HELP version 3 using a broader range of test field data. Received: 10 January 1995 · Accepted: 14 November 1995     

Self-organization of recent rhythmic iron-manganese precipitations in underground mines in the Harz mountains

A recent early diagenetic banded iron-manganese mud has been forming underground in a closed lead-zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloid-chemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.     

太阳系质心参考系与地心参考系中的激光测距问题

给出了太阳系质心参考系（BRS）和地心参考系（GRS）中的相对论激光测距理论模型,并且利用现有的坐标变换关系证明两种模型在毫米级的精度上是完全等价的。最后指出,由IERS推荐的坐标变换公式与激光测距模型之间存在不自洽性,这种不自恰性对激光测月（LLR）的影响可达约10cm。     

大江截流期间历年强降水过程的天气系统分析

该文利用历史天气图资料，统计了１９６１－１９９４年１０月至次年１月逐次强降水过程，分析了强降水过程的影响天气系统特征及演变规律，其结果有助于实时预报业务做好长江三峡工程大江截流的气象保障工作。     

Laboratory studies of some environmental variables controlling sulfur emissions from plants

Several trace sulfur gases that can have a significant influence on atmospheric chemistry are emitted from biological systems. In order to begin to address biological questions on the mechnisms of production of such gases, laboratory-scale experiments have been developed that reproduce such emissions under controlled conditions. Using a flux chamber technique, flats containing soil, or soil plus plants were sampled for the net fluxes of sulfur gases. The major sulfur gas emitted from all the plants tested (corn, alfalfa, and wheat) was dimethyl sulfide (DMS). Alfalfa and wheat also emitted lesser amounts of methanethiol, variable amounls of hydrogen sulfide, and in some experiments wheat emitted carbon disulfide. The use of a plant incubator allowed a systematic study of the effects of variables such as temperature, photon flux, and carbon dioxide levels, on these emissions. Fluxes of all the emitted sulfur gases increased exponentially with increasing air temperature, and increased with increasing photon flux up to a saturation level of \~300 E/m^–2 sec^-1. Three to four-fold changes in DMS flux were observed during light to dark or dark to light transitions. By varying the CO₂ content of the chamber flush gas, it was shown that the observed sulfur fluxes from corn and alfalfa were not related to the CO₂ concentration. Growing these crop plants through holes in a Teflon soil-covering film allowed a separate determination of soil and foliage emissions and substantiation of the light dependent uptake of COS by growing vegetation observed in previous field studies.     

Chaotic behaviour in a low-order unforced,inviscid barotropic model

A low-order model of the unforced, inviscid barotropic model is examined as a dynamical system. Analytic solutions, consisting of linear and nonlinear oscillations (Rossby waves), are obtained in appropriate limiting initial conditions. These solutions are periodic. With less restrictive initial conditions the system shows quasi-periodic behaviour at low energies and chaotic behviour at high energies. This transition is accompanied by frequency-locking and period-doubling. Quasi-periodic and chaotic behaviour may coëxist in phase space for the same values of the model invariants. The results are interpreted in terms of perturbed integrable Hamiltonian systems. Considerations of the low-frequency variability of the atmosphere are also made.     

Least squares parameter estimation in chaotic differential equations

A recent least squares algorithm, which is designed to adapt implicit models to given sets of data, especially models given by differential equations or dynamical systems, is reviewed and used to fit the Hénon-Heiles differential equations to chaotic data sets.This numerical approach for estimating parameters in differential equation models, called theboundary value problem approach, is based on discretizing the differential equations like a boundary value problem,e.g. by a multiple shooting or collocation method, and solving the resulting constrained least squares problem with a structure exploiting generalized Gauss-Newton-Method (Bock, 1981).Dynamical systems like the Hénon-Heiles system which can have initial values and parameters that lead to positive Lyapunov exponents or phase space filling Poincaré maps give rise to chaotic time series. Various scenarios representing ideal and noisy data generated from the Hénon-Heiles system in the chaotic region are analyzedw.r.t. initial conditions, parameters and Lyapunov exponents. The original initial conditions and parameters are recovered with a given accuracy. The Lyapunov spectrum is then computed directly from the identified differential equations and compared to the spectrum of the true dynamics.presently at IWR, Universität Heidelberg, Im Neuenheimer Feld 368, D-6900 Heidelberg, Germany     

An Archean(?) to Paleozoic Evolution for a Garnet Peridotite Lens with Sub-Baltic Shield Affinity within the Seve Nappe Complex of Jamtland, Sweden, Central Scandinavian Caledonides

Mineralogical, isotopic, geochemical and geochronological evidencedemonstrates that the Friningen body, a garnet peridotite bodycontaining garnet pyroxenite layers in the Seve Nappe Complex(SNC) of Northern Jämtland, Sweden, represents old, certainlyProterozoic and possibly Archean, lithosphere that became incorporatedinto the Caledonian tectonic edifice during crustal subductioninto the mantle at c. 450 Ma. Both garnet peridotite and pyroxenitecontain two (M₁ and M₂) generations of garnet-bearing assemblagesseparated by the formation of two-pyroxene, spinel symplectitearound the M₁ garnet and the crystallization of low-Cr spinel_1Cin the matrix. These textures suggest initial high-pressure(HP) crystallization of garnet peridotite and pyroxenite succeededby decompression into the spinel stability field, followed byrecompression into the garnet peridotite facies. Some pyroxenitelayers appear to be characterized solely by M₂ assemblages withstretched garnet as large as several centimeters. Laser ablationmicroprobe–inductively coupled plasma mass spectrometryRe–Os analyses of single sulfide grains generally definemeaningless model ages suggesting more than one episode of Reand/or Os addition and/or loss to the body. Pentlandite grainsfrom a single polished slab of one garnet peridotite, however,define a linear array on an Re–Os isochron diagram that,if interpreted as an errorchron, suggests an Archean melt extractionevent that left behind the depleted dunite and harzburgite bodiesthat characterize the SNC. Refertilization of this mantle bymelts associated with the development of the pyroxenite layersis indicated by enriched clinopyroxene Sr–Nd isotope ratios,and by parallel large ion lithophile-enriched trace elementpatterns in clinopyroxene from pyroxenite and the immediatelyadjacent peridotite. Clinopyroxene and whole-rock model Sm–Ndages (T_DM = 1·1–2·2 Ga) indicate that fertilizationtook place in Proterozoic times. Sm–Nd garnet₂–clinopyroxene₂–wholerock ± orthopyroxene₂ mineral isochrons from three pyroxenitelayers define overlapping ages of 452·1 ± 7·5and 448 ± 13 Ma and 451 ± 43 Ma (2