A ~4500 yr record of river floods obtained from a sediment core in Lake Atnsjøen, eastern Norway

To extend the historical record of river floods in southern Norway, a 572-cm long sediment core was retrieved from 42 m water depth in Atnsjøen, eastern Norway. The sediment core contains 30 light gray clastic sediment layers interpreted to have been deposited during river floods in the snow/ice free season. In the upper 123 cm of the core, four prominent flood layers occur. The youngest of these overlap with the historical record. The thickest (flood layer 5) possibly reflects a general increase in river-flood activity as a result of the post-Medieval climate deterioration (lower air temperatures, thicker and more long-lasting snow cover, and more frequent rain/snow storms) associated with the Little Ice Age. The most pronounced pre-historic flood layers in the core were, according to an age model based on linear regression between eleven bulk AMS radiocarbon dates, deposited around 4135, 3770, 3635, 3470, 3345, 2690, 2595, 2455, 2415, 2255, 2230, 2150, 2120, 1870, 1815, 1665, 1640, 1480, 1400, 1380, 1290, 935, 885, 670, 655 and 435 cal. BP (BP = AD 1950). The mean return period of the river flood layers is, according to the linear regression age model, ~ 150 ± 30 cal. yr (mean ± 1 S.E.).     

The effect of garnet cell volume on the distribution of Mg and Fe in garnet exchange equilibria

The distribution of Mg in garnet exchange equilibria has been examined in three regional metamorphic and four eclogitic parageneses. Garnet cell volume has been found to have a significant effect on the distribution of Mg between garnet and coexisting ferromagnesian minerals. When the activity of Mg is corrected for the variation in cell volume, the range in variation of the distribution coefficients is strongly reduced within each group. Also the relative positions of the different groups in the distribution diagrams are in better accordance with geological evidence of crystallization temperatures. It is proposed that the effect of the garnet cell volume on the Mg distribution may be used as a geobarometer. The distribution of Ca between garnet and plagioclase is also discussed and it is found that the Ca partitioning is not suitable for geobarometry, as this partioning is dependent on the Mg/Fe ratio of the garnet.     

A method of calculating the non‐linear seismic response of a building braced with viscoelastic dampers

Buildings are continually subject to dynamic loads, such as wind load, seismic ground motion, and even the load from internal utility machines. The recent trend of constructing more flexible high‐rise buildings underscores the importance of including viscoelastic dampers in building designs. Viscoelastic dampers are used to control the dynamic response of a building. If the seismic design is based only on the linear response spectrum, considerable error may occur when calculating the seismic response of a building; rubber viscoelastic dampers show non‐linear hysteretic damping that is quite different from viscous damping. This study generated a non‐linear response spectrum using a non‐linear oscillator model to simulate a building with viscoelastic dampers installed. The parameters used in the non‐linear damper model were obtained experimentally from dynamic loading tests. The results show that viscoelastic dampers effectively reduce the seismic displacement response of a structure, but transmit more seismic force to the structure, which essentially increases its seismic acceleration response. Copyright © 2003 John Wiley & Sons, Ltd.     

Input and system identification of the Hualien soil–structure interaction system using earthquake response data

This paper presents an input and system identification technique for a soil–structure interaction system using earthquake response data. Identification is carried out on the Hualien large‐scale seismic test structure, which was built in Taiwan for international joint research. The identified quantities are the input ground acceleration as well as the shear wave velocities of the near‐field soil regions and Young's moduli of the shell sections of the structure. The earthquake response analysis on the soil–structure interaction system is carried out using the finite element method incorporating the infinite element formulation for the unbounded layered soil medium and the substructured wave input technique. The criterion function for the parameter estimation is constructed using the frequency response amplitude ratios of the earthquake responses measured at several points of the structure, so that the information on the input motion may be excluded. The constrained steepest descent method is employed to obtain the revised parameters. The simulated earthquake responses using the identified parameters and input ground motion show excellent agreement with the measured responses. Copyright © 2003 John Wiley & Sons, Ltd.     

Natural deterioration and conservation treatment of the granite standing Buddha of Daejosa Temple, Republic of Korea

The Daejosa Buddha is formed of highly weathered coarse grained biotite granite. The main body is dark green due to a covering of lichens. The main body of the Buddha has developed nearly vertical, horizontal and oblique joint systems. Results of physical properties for the rock samples from the Daejosa Buddha are lower than for normal fresh granite as the primary minerals of the host rocks have been altered to clay and iron hydroxide minerals. Spore and mycelium of green algaes and some plants cover the surface of the standing Buddha and fill the pore space of the surrounding rocks. Considering the weathering and state of deterioration, the Buddha statue requires conservation treatment. Restoration may be largely divided into the head part, upper and lower parts, and the back side of the Buddha. The head and the cap rock were joined and restored with unslaked lime filling. The head and stone crown of the Buddha were fitted and restored using an epoxy type resin with high viscosity that was mixed with granite powder and talc as petro-fillers. For the back side, resin was applied for reinforcement. Araldite and hardener of low viscosity that were used with the addition of glass fibers. Finally, texture and color matching treatments were carried out.     

Performance of Singapore Integrated Multiple Reference Station Network (SIMRSN) for RTK Positioning

Conventional RTK positioning is usable, but requires the use of a local base station. It is also restricted by the effects of the de-correlate atmospheric refraction on the GPS signal, which limits the use of the RTK positioning up to distances of 10–15 km from the reference station to the user. With a multiple reference station network approach, precise RTK positioning capability may be extended for a much larger area. The Singapore Integrated Multiple Reference Station Network (SIMRSN) has been established for this purpose. Using an existing method termed linear combination method, the multiple reference station network corrections are generated for the user on an epoch by epoch, satellite-by-satellite basis. A residual-based adaptive Kalman filter is proposed to improve network correction availability. The VRS concept is used to transmit corrections to the user for RTK positioning. Field tests were conducted to demonstrate the general performance of SIMRSN. The tests confirmed that RTK positioning within a multiple reference station network can provide the user with better than 3 cm in horizontal position, the height accuracy is in the range of 1–7 cm, and the average TTF (Time To Fix) are 46 and 76 s during GLC station and LPR station tests, respectively. With this highly efficient survey technique, the user needs only to be equipped with a single GPS receiver. This reduces equipment and manpower costs compared with traditional RTK positioning using a specially set up reference station. The multiple reference station framework also paves the way for various other applications beyond the traditional surveying profession. Electronic Publication     

Coastal currents and eddies and their interaction with topography

The nonlinear interaction of vorticity driven coastal currents and eddies with topography is studied. The topography is either a semi-infinite escarpment perpendicular to the coast (such that topographic waves propagate toward the coast) or a semi-circular canyon or seamount attached to the coast. Assuming a piecewise constant potential vorticity distribution, the quasigeostrophic equations are solved using contour dynamics. Offshore propagating dipole eddies occur, whenever a coastal current or eddy interacts with escarpment and canyon topographies. The size and frequency at which dipoles form are found to depend on the vorticity of the current and amplitude of the topography. However, for a seamount, little eddy shedding is observed and the coastal current or eddy skirts around topography.     

Weathering and deterioration of rock properties of the Dabotap pagoda (World Cultural Heritage), Republic of Korea

The Bulkugsa Dabotap pagoda was built in AD 761, and designated as World Cultural Heritage by UNESCO in 1995. The ca. 270 blocks used in the construction of the pagoda consist mainly of white grey alkali granite with medium-grained equi-granular texture and small mialolitic cavities. Small quantities of biotite granite, granodiorite, gabbroic and tuffaceous rocks were also used. Some overlapping blocks are very damp. The pagoda body is inclined toward the northeast owing to differential loading. Fractures and artificial deterioration of the pagoda are not serious, but the surfaces of blocks show exfoliations that indicate granular decomposition of minerals. The supporting rocks and the round handrail of the octagonal second floor are too weathered to be treated and are being replaced. The roof stones on the first and second floor are seriously damaged because there is no drainage route for rainwater. The joints between blocks have fractures that cross each other; they have been further damaged by inserting concrete, cement mortar, rock fragments and iron plates. This has accelerated discoloration and fractures. Widespread colonization by algae, fungi, lichens and bryophytes has occurred on the margins and surfaces roof stones of the pagoda. Chemical treatment will be necessary to remove the vegetation cover.     

Lipids and trophic linkages in harp seal (Phoca groenlandica) from the eastern Barents Sea

Fatty acid profiles and lipid biomarkers from 20 harp seals were used to investigate the foraging ecology of harp seals and the transfer of energy through the Franz Josef Land-Novaya Zemlya food chain. High levels of the Calanus fatty acid trophic markers (FATMs) 20:1(n-9) (mean 14.6%) and 22:1(n-11) (mean 6.5%), together with the typical dinoflagellate FATMs 22:6(n-3) (mean 6.5%) and C18PUFA (mean 5.5%), were found in blubber samples. Based on the analyses of the fatty acid profiles separated by principal component analysis, we confirmed the importance of polar cod ( Boreogadus saida ) and the pelagic amphipod Themisto libellula in the diet of harp seal. The high levels of 22:6(n-3), C18PUFA and C20 and C22 FATMs show that the harp seal lipids mainly originate from dinoflagellates consumed by Calanus copepods.     

Untersuchungen zur Abtrennung von Schwermetallen aus Abwasser mit frisch hergestelltem Magnetit Studies for Separation of Heavy Metals from Wastewater with Freshly Precipitated Magnetite

The separation of heavy metals from wastewater may be improved by precipitation/flocculation with iron- or aluminium salts. Often, the resulting products are voluminous, water-containing, amorphous hydroxides which show only limited flocculation properties and may possibly pose problems with the technical separation from the aqueous phase. The application of magnetite could be advantageous because magnetite is ferromagnetic and can be separated very quickly in a magnetic field. First of all, a simple preparation method for magnetite was studied. Pure magnetite could be prepared by mixing an iron(II) salt solution with an equivalent amount of sodium hydroxide at room temperature without oxidation by air. The required reaction time was only 3 hours. For the precipitation of heavy metals from an electroplating wastewater, a better metal elimination and smaller sludge volumes resulted with that artificially produced magnetite in comparison with a precipitation by NaOH. Thereby not only the adsorption of metals was established but also coagulation effects of the magnetite sludge with small metal hydroxide particles. By means of the experimental results. sorption of nickel and chromium was compiled as function of pH and precipitation time. Because freshly precipitated magnetite shows very good sorption and flocculation properties, and pH of precipitation may be lower, its use in high gradient magnetic separation (HGMS) could be more effective for metal elimination than magnetite powder.