结合全球气候模型预测结果概率分析融化深度

A probabilistic approach may be adopted to predict freeze and thaw depths to account for the variability of (1) material properties, and (2) contemporary and future surface energy input parameters (e.g.air temperatures, cloud cover, snow cover) predicted with global climate models. To illustratc the probabilistic approach, an example of the prediction of thaw depths in Fairbanks, Alaska, is considered, More specifically, the Stefan equation is used together with the Monte Carlo simulation technique to make a probabilistic prediction of thaw penetration. The simulation results indicate that the variability in material properties, surface energy input parameters, and temperature data can lead to significant uncertainty in predicting thaw penetration. The Taylor series method was performed to determine the mean and standard deviation of thaw penetration and the results were compared to the Monte Carlo simulation results. The close comparison of the results suggests that the simpler Taylor series method may be applied to many cold regions problems to account for the variability of input parameters.     

Landforms and landscape evolution in the Skardu,Shigar and Braldu Valleys,Central Karakoram

The Central Karakoram, which includes K2 in Pakistan, is one of the most rapidly rising areas on Earth and exhibits complex topography and extreme relief. Impressive valley fills and glacial landforms are present throughout the valleys. The dynamics of landscape evolution of the region are currently not well understood. Consequently, the landforms were mapped and assessed in the Skardu, Shigar, and Braldu valleys, to elucidate the spatio-temporal scale dependencies of surface processes active in the region. These valleys were examined using geomorphic field methods, remote sensing, geomorphometry, and terrestrial cosmogenic nuclides (TCNs) surface exposure dating. The glaciers in this region have oscillated considerably throughout the Late Quaternary, and four glacial stages have been recognized including at least six glacial advances. Surface processes readjusted after glacier retreat, and ubiquitous mass movements and catastrophic landsliding transported material from steep slopes to valley bottoms, while glaciofluvial meltwater and glacier outburst floods redistributed sediment down valley. Glacier geochronology and late Holocene ages of the outburst flood deposits indicate that landscape evolution has been dominated by glaciation and paraglaciation during the late Quaternary.     

2D acoustic‐elastic coupled waveform inversion in the Laplace domain

Although waveform inversion has been intensively studied in an effort to properly delineate the Earth's structures since the early 1980s, most of the time‐ and frequency‐domain waveform inversion algorithms still have critical limitations in their applications to field data. This may be attributed to the highly non‐linear objective function and the unreliable low‐frequency components. To overcome the weaknesses of conventional waveform inversion algorithms, the acoustic Laplace‐domain waveform inversion has been proposed. The Laplace‐domain waveform inversion has been known to provide a long‐wavelength velocity model even for field data, which may be because it employs the zero‐frequency component of the damped wavefield and a well‐behaved logarithmic objective function. However, its applications have been confined to 2D acoustic media. We extend the Laplace‐domain waveform inversion algorithm to a 2D acoustic‐elastic coupled medium, which is encountered in marine exploration environments. In 2D acoustic‐elastic coupled media, the Laplace‐domain pressures behave differently from those of 2D acoustic media, although the overall features are similar to each other. The main differences are that the pressure wavefields for acoustic‐elastic coupled media show negative values even for simple geological structures unlike in acoustic media, when the Laplace damping constant is small and the water depth is shallow. The negative values may result from more complicated wave propagation in elastic media and at fluid‐solid interfaces. Our Laplace‐domain waveform inversion algorithm is also based on the finite‐element method and logarithmic wavefields. To compute gradient direction, we apply the back‐propagation technique. Under the assumption that density is fixed, P‐ and S‐wave velocity models are inverted from the pressure data. We applied our inversion algorithm to the SEG/EAGE salt model and the numerical results showed that the Laplace‐domain waveform inversion successfully recovers the long‐wavelength structures of the P‐ and S‐wave velocity models from the noise‐free data. The models inverted by the Laplace‐domain waveform inversion were able to be successfully used as initial models in the subsequent frequency‐domain waveform inversion, which is performed to describe the short‐wavelength structures of the true models.     

A study of the three-dimensional groundwater flow system in an upland area of Japan

A three-dimensional finite difference model was developed to study the groundwater flow system in an upland area bordering a lake. For a general perspective of the groundwater flow system, a steady state three-dimensional flow was employed. Having determined the flow net by using a three-dimensional model, the flow volumes under natural conditions have been used to establish the parameter values and for the analyses of flow patterns. Further, to study the effects of human impact and precipitation on groundwater flow conditions in a small area, a transient three-dimensional simulation was performed. Environmental tritium was used to trace the regional groundwater movement to verify the three-dimensional mathematical model. Results obtained using the three-dimensional mathematical model approach and tritium concentration analyses were in close agreement. The results demonstrated that the groundwater flow system should be analysed using a three-dimensional geometric concept of groundwater movement.     

Molecular characterization of four genes highly expressed during megalopa stage in Chinese mitten crab,Eriocheir sinensis

Ocean Science Journal - The molecular markers to distinguish different larval stages have various applications in ecological studies. Using the differential display RT-PCR technique, we isolated...     

Consolidation settlement properties of seashore landfills for municipal solid wastes in Korea

The large amount of wastes is generated in metropolitan area where population is heavily concentrated. As a result, treatment of wastes became a social problem and geotechnical problems related to landfill have emerged in Korea. Settlement behavior of waste landfill is similar to behavior of peat that possesses relatively small time-dependent secondary compression alongside large initial compression. A number of researchers published their own settlement computations. However, accurate computation method for waste-reclaimed landfill has yet to be determined as the settlement mechanism is very complicated. Hence, it is important to examine the accurate settlement behavior of reclaimed ground by comparing the material properties from laboratory test and field monitoring and comparing the results with the theoretical equation. This study determines the consolidation coefficients according to the change of organic contents through the total volume reduction in fresh waste layer and initial void ratio change and examines the feature of settlement in each load stage. Moreover, the article attempts to investigate the characteristics of consolidation of the relevant reclaimed landfill and to determine the suitability of the equation by comparing the variables in theoretical equations obtained from the laboratory test and field monitoring. Moreover, to verify the compression characteristics of the waste-reclaimed landfill upon loading, consolidation test results were analyzed to conduct index study on the consolidation characteristics of the waste-reclaimed landfill.