Ecological Corridor Construction Based on Least-Cost Modeling Using Visible Infrared Imaging Radiometer Suite (VIIRS) Nighttime Light Data and Normalized Difference Vegetation Index

Anthropic pressure is one of the main drivers of landscape change and biodiversity loss. Artificial nighttime light, which can affect species behavior, is an important human-induced threat to biodiversity, but it is often ignored in ecological connectivity research. To mitigate the adverse impacts of artificial lighting on biodiversity, this study integrates artificial nighttime light in landscape ecology and analyzes the influence of artificial nighttime light on landscape connectivity. A quantitative approach integrating nighttime light brightness from a Visible Infrared Imaging Radiometer Suite (VIIRS) with a normalized difference vegetation index (NDVI) from a Moderate-resolution Imaging Spectroradiometer (MODIS) is proposed to estimate the matrix resistance, which can identify the sensitive areas that are disrupted by nighttime light. It was found that the nightscape in the study area is significantly disrupted by nighttime light and the matrix resistance in the center of the study area significantly increases. Compared to the least-cost routes from the NDVI, the “dark” least-cost ecological corridors constructed using our approach apparently change in both location and distance. The corridors moved to the outer suburbs and rural areas, and the maximum increase in distance of the least-cost paths was 37.94%. Due to less disturbance from human activity and the maintenance of a pristine nightscape, “dark” ecological corridors can reduce the adverse effects of night lights and contribute to biodiversity. However, natural habitats have been greatly affected by nighttime light with the increase in global illumination, and it is essential that we improve public awareness of light pollution and formulate light-reduction policies and legislation.

ELECTRICAL PROPERTIES OF FLY ASH GEOPOLYMER COMPOSITES WITH GRAPHITE CONDUCTIVE ADMIXTURES

Construction materials with increased electrical conductivity could be possibly used in health monitoring of structures (stress, deformation, damages), their maintenance or traffic monitoring. The aim of this study was the application of functional filler and its influence on the electrical properties of the alkali-activated fly ash matrix. The graphite powder was added to the reference material in the amount of 2–10 %. Besides the assessment of the critical amount of filler necessary to achieve a percolation threshold in the structure of the composite, the effect on the electrical properties of the matrix (resistance, capacitance, conductivity) was determined. The optimal amount of filler was also determined with respect to the changes in microstructure of the binder and its mechanical properties.

A New Constitutive Relation for Describing the Flow through Porous Media with Unsaturated–Saturated Transition

The present work proposes an adequate constitutive relation to treat the process of filling with a fluid porous medium. This relation assures the problem to remain hyperbolic when the porous medium is saturated by the fluid. When the fluid fraction reaches porosity, the proposed constitutive relation increases the porous matrix resistance to more fluid inlet due to an important feature: it is a continuous and differentiable function with first derivative being also an increasing function. This allows assuring that the fluid fraction may exceed the porosity only by a very small value, making the constitutive relation realistic. Some examples compare this new constitutive relation with previous ones, highlighting its advantages.

New Insights Into Controlling Sub-Micron Failure Mechanisms in Composites Using Discrete Functionalized Multiwall Carbon Nanotubes

New technology has been developed that enables multiwall carbon nanotubes to be discrete, high aspect ratio and well bonded to the composite matrix of choice. Several composite types are examined using tubes of diameter about 12 nm and length about 700nm. Fully discrete, well-bonded tubes are shown to significantly enhance the matrix resistance to fracture and can be placed between fiber plies of composites. The challenges of maintaining the exfoliated state of discrete multiwall carbon nanotubes during composite part assembly from the liquid prepolymer to the cured part are discussed.