Stochastic grid bundling method for backward stochastic differential equations

ABSTRACT

In this work, we apply the Stochastic Grid Bundling Method (SGBM) to numerically solve backward stochastic differential equations (BSDEs). The SGBM algorithm is based on conditional expectations approximation by means of bundling of Monte Carlo sample paths and a local regress-later regression within each bundle. The basic algorithm for solving the backward stochastic differential equations will be introduced and an upper error bound is established for the local regression. A full error analysis is also conducted for the explicit version of our algorithm and numerical experiments are performed to demonstrate various properties of our algorithm.     

Research on corrosion performance of 6061 aluminum alloy in salt spray environment

Salt spray corrosion test was carried out on 6061 aluminum alloy, and quasi-static tensile test at room temperature was carried out on the sample with universal testing machine. The effect of salt spray corrosion on the mechanical properties of 6061 aluminum alloy was studied by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and electrochemistry. The corrosion rate of 6061 aluminum alloy was quantitatively characterized by different corrosion parameters. It was found that local corrosion of 6061 aluminum alloy occurred in salt spray environment, mainly pitting corrosion and intergranular corrosion. With the increase of corrosion time, the polarization resistance of 6061 aluminum alloy decreases, and the corrosion rate significantly increases. The average corrosion rate and the maximum corrosion rate of 6061 aluminum alloy were characterized by corrosion weight loss and corrosion pit depth. And they can be transformed into each other. The mechanical properties of 6061 aluminum alloy were mainly affected by the depth of corrosion pit. With the increase of corrosion time, the tensile strength and fracture strain decreased, resulting in poor plasticity of the sample. At the same time, the change of elongation of 6061 aluminum alloy can be accurately predicted by the depth of corrosion pit.     

Universitärer Forschungscluster „Sustainable Technologies in Metal Production and Processing” (STMP)

Foundation of a university research cluster — Co-operation along the value creation chain from raw materials to components — Evidence of joint performance offers — Utilization of synergies — Integration of Christian Doppler Laboratories — Flexible arrangement of co-operations and networks     

The Effects of Isolation and Acid Mine Drainage on Fish and Macroinvertebrate Communities of Monday Creek, Ohio, USA

Isolated headwater streams in mined watersheds may have good water quality and fish habitat, yet be disconnected from immigration sources by stream segments impaired by acid mine drainage (AMD). Studies of fish and macroinvertebrate communities, habitat, and a number of hydrochemical parameters in Monday Creek, Ohio, show that AMD eliminates fish communities and severely limits macroinvertebrate communities in directly affected tributaries. Isolated headwaters in the heavily mined Monday Creek watershed have relatively good water quality and habitat, but poor fish communities. Comparison of isolated Monday Creek headwaters with non-isolated reaches in unmined watersheds indicates that differences in fish communities are attributable to isolation. Fish communities in isolated headwaters have lower Indices of Biotic Integrity (IBI) than comparable non-isolated communities, reduced species numbers, and lower numbers of individuals, despite suitable habitat as measured by the Qualitative Habitat Evaluation Index (QHEI). Comparison of macroinvertebrate communities shows higher Invertebrate Community Indices (ICI), and no apparent species loss, which can be attributed to the obligate flight stage in the life cycle of many macroinvertebrates, which enables them to overcome aquatic barriers. The implication of this research is that there is an opportunity for recovery of depleted fish communities in large AMD-isolated areas with good water quality, suitable habitat, and intact macroinvertebrate communities, by downstream treatment or source control of AMD to create aquatic corridors for fish immigration.     

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.     

Modeling investment priorities for national road improvements: A case study of Korea

The paper addresses specific problems associated with formulating investment priorities for national road improvements in Korea. More specifically, the objectives of the paper are (1) to present a model for formulating investment priorities for road improvements that may be useful to developing countries, (2) to test the model with simplified data for deriving investment priorities for Korea's road improvements, and (3) to learn lessons that can be applicable to other developing countries with particular respect to recommending investment priorities for road improvements. The study results are useful for planners, in developing countries, and also for evaluation analysts in funding institutions who are confronted with evaluating investment priorities for deteriorating road conditions.