A mathematical model of channel deformations in permafrost zone rivers

A mathematical model is presented, allowing the calculation of channel deformations of permafrost zone rivers caused by thermo-erosional niching under the effect of waves of different origin under the conditions of growing ambient temperature. The model is based on equations of transient fluid motion in two-dimensional formulation, Stefan equation for determining the displacement of water-ice phase transition interface, and mass conservation equations for transported sediments (deformation equations). The model was tested against a particular case of steady flow based on data of a laboratory experiment. Numerical experiments revealed the key factors of the process and allowed the impact of waves with different duration and intensity (spring floods and releases from engineering structures) on river channel to be analyzed.     

Formation conditions and the environmental state of fresh groundwater in dimitrovgrad area by isotopic-hydrochemical data

Integrated uranium-isotopic and microhydrochemical studies were used to develop an indicator model of formation and circulation of drinking groundwater of Neogene-Quaternary deposit and to assess their current ecological state. The paths of subsurface flows of infiltration recharge are identified and traced, and the zones of deep-water inflow are identified and delimited. The total pollution index of groundwater from Neogene-Quaternary aquifer system was found to far in excess of the acceptable level because of an elevated concentrations of iron, manganese, and phosphorus of anthropogenic and deep-seated origin.     

A smoothed ANOVA model for multivariate ecological regression

Smoothed analysis of variance (SANOVA) has recently been proposed for carrying out disease mapping. The main advantage of this approach is its conceptual simplicity and ease of interpretation. Moreover, it allows us to fix the combination of diseases of particular interest in advance and to make specific inferences about them. In this paper we propose a reformulation of SANOVA in the context of ecological regression studies. This proposal considers the introduction in a non-parametric way of one (or several) covariate(s) into the model, explaining some pre-specified combinations of the outcome variables. In addition, random effects are also incorporated in order to model geographical variation in the combinations of outcome variables not explained by the covariate. Lastly, the model permits the decomposition of the variance in the set of outcome variables into different orthogonal components, quantifying the contribution of every one of them. The proposed model is applied to the geographical analysis of mortality due to malignant stomach neoplasm among women resident in the city of Barcelona (Spain). The available outcome variables are deaths grouped into two time periods, and a socioeconomic deprivation index is included as a covariate. The model has been implemented through INLA, a novel inference tool for Bayesian statistics.     

The value of multiple earthquake missions: the EEFIT L’Aquila Earthquake experience

In November 2012 EEFIT launched its first ever return mission to an earthquake affected site. The L’Aquila Earthquake site was chosen as this is a recent European event of interest to the UK and European earthquake engineering community. The main aims of this return mission were to document the earthquake recovery process and this paper presents an overview of the post-disaster emergency phase and transition to reconstruction in the Aquila area after the earthquake. It takes an earthquake engineering perspective, highlighting areas mainly of interest to the fields of structural/seismic engineering and reconstruction management. Within the paper, reference is made to published literature, but also to data collected in the field during the return mission that would not otherwise have been available. The paper presents some specific observations and lessons learned from the L’Aquila return mission. However, in light of current international efforts in conducting return missions, the paper ends with some reflections on the value that return missions can provide to the field of earthquake engineering in general, based on the EEFIT L’Aquila experience.     

广西防城港海域沉积物特征及输运趋势

通过对2010―2011年在广西防城港海域表层沉积物所取样品进行粒度实验,并利用二维沉积物粒径趋势分析模型进行了粒径输运趋势分析。结果表明,研究区海域底质沉积物类型主要为砂、粉砂质砂、砾石质砂、砂-粉砂-黏土、黏土质粉砂和砂质粉砂等6种。粒度参数在空间分布上,沿岸和西部海域中值粒径较粗,分选中等或较好,偏态呈正偏或极正偏,在海湾口处呈负偏或极负偏;东南部海域粒径较细,分选系数差,偏态呈负偏或近对称。根据沉积物输运趋势方向不同,将研究海域分为3个区：沿岸海域主要离岸输送,方向由北向南;东南部海域的沉积物输运趋势向中间汇聚,形成一个沉积中心;西南部海域,沉积物输运方向偏北。     

Logistic regression versus artificial neural networks: landslide susceptibility evaluation in a sample area of the Serchio River valley,Italy

This article presents a multidisciplinary approach to landslide susceptibility mapping by means of logistic regression, artificial neural network, and geographic information system (GIS) techniques. The methodology applied in ranking slope instability developed through statistical models (conditional analysis and logistic regression), and neural network application, in order to better understand the relationship between the geological/geomorphological landforms and processes and landslide occurrence, and to increase the performance of landslide susceptibility models. The proposed experimental study concerns with a wide research project, promoted by the Tuscany Region Administration and APAT-Italian Geological Survey, aimed at defining the landslide hazard in the area of the Sheet 250 “Castelnuovo di Garfagnana” (1:50,000 scale). The study area is located in the middle part of the Serchio River basin and is characterized by high landslide susceptibility due to its geological, geomorphological, and climatic features, among the most severe in Italy. Terrain susceptibility to slope failure has been approached by means of indirect-quantitative statistical methods and neural network software application. Experimental results from different methods and the potentials and pitfalls of this methodological approach have been presented and discussed. Applying multivariate statistical analyses made it possible a better understanding of the phenomena and quantification of the relationship between the instability factors and landslide occurrence. In particular, the application of a multilayer neural network, equipped for supervised learning and error control, has improved the performance of the model. Finally, a first attempt to evaluate the classification efficiency of the multivariate models has been performed by means of the receiver operating characteristic (ROC) curves analysis approach.     

Small-scale, high-precision and high-accuracy determination of Poisson’s ratios in cohesive marine sediments

Poisson’s ratio (static) appears as a parameter in models of soft-sediment geomechanical processes such as gas bubble formation and bioturbation, and in a number of practical applications, including acoustic imaging, but is rarely measured in soft near-surface (upper 20 cm) marine sediments. A new uniaxial apparatus was developed to assess Poisson’s ratios of cylindrical samples of soft cohesive sediments under finite-strain, unconfined, undrained conditions. No constraining membrane around the sample is necessary in the instrument. By monitoring the fluid level in a capillary, changes in sample volume can be determined to high precision (reproducibility). Measurements on reference materials, i.e., gelatine and polyurethane, also indicate high accuracy (veracity). For natural sediments from Nova Scotia, Canada, Poisson’s ratios range from 0.4951 to 0.5 with no indication of anisotropy; therefore, such sediments act as incompressible solids to short-term/small-magnitude stresses, as occur during bubble formation and infaunal movement.     

Reduction of short-lived atmospheric pollutant emissions as an alternative strategy for climate-change moderation

The current state of studies on short-lived atmospheric constituents (greenhouse gases and aerosols) is reviewed. They have short atmospheric lifetimes (from several days to a few years) and can significantly affect the environment and climate. We propose reducing the emissions of these constituents as an alternative to the reduction of man-made carbon dioxide releases. We consider methane, hydrofluorocarbons, tropospheric ozone, and various aerosols (primarily, black carbon); discuss their atmospheric sources and destruction mechanisms; evaluate their content, atmospheric emissions, and climate impacts; and recommend efficient actions for the nearest future.     

Experimental investigations of the effect of cloud-medium modification by salt powders

The results of experimental investigations into the action of polydispersion salt powders on model cloud media are presented. The results of experiments show a considerable positive effect of the modification of convective clouds by salt powders in order to obtain additional precipitation. The introduction of polydispersion salt powder into a forming cloud medium leads to the appearance of large cloud droplets and to the droplet-spectrum broadening. This result is a positive factor for the stimulation of coagulation processes and further precipitation formation. No “overseeding” phenomenon (when, instead of the enlargement of droplets, their sizes decrease and the concentration of cloud droplets increases) is observed at rather high mass concentrations of the introduced powder.