—Widespread establishment of seedling aspen (Populus tremuloides) occurred in Yellowstone National Park (YNP) following the extensive1988 fires. Aspen stands occupy ;2% of YNP and aspen stems are intensively browsed by native ungulates. Chemical composition, especially secondary compounds, may influence levels of herbivory and, hence, survival of aspen, but concentrations of such compounds in a...

As human activity continues to increase CO2 and O3, broad expanses of north temperate forests will be simultaneously exposed to elevated concentrations of these trace gases. Although both CO2 and O3 are potent modifiers of plant growth, we do not understand the extent to which they alter competition for limiting soil nutrients, like nitrogen (N). We quantified the acquisition of soil N in two 8...

In Rocky Mountain National Park (RMNP), aspen (Populus tremuloides Michx.) has been observed to be declining on elk (Cervus elaphus nelsoni) winter range for many decades. To support elk management decisions, the SAVANNA ecosystem model was adapted to explore interactions between elk herbivory and aspen dynamics. The simulated probability of successful vegetative regeneration for senescent aspe...

Nowadays, membrane processes are widely used for high purity Nitrogen production. Separation of air by membranes is a flexible process in which the investment and operational costs are lower than for example adsorption or cryogenic processes. Such processes are based on relative permeability of air components which are transported by the pressure difference between two sides of the membrane. M...

One of the most important methods of transporting natural gas in Iran and other parts of the world is the utilization of a network of pipelines. Compression station and turbo compressor units play an important role in gas supply through pipelines. One of the primary concerns in these units is the reduction of fuel consumption. By cooling of exhaust gas from the source station, the pressure drop...

Aiming for the better environmental and economic performance of traditional engines, waste heat recovery (WHR) technologies are actively studied to find their most beneficial applications. In this work, inverted Brayton cycle (IBC) is investigated as a potential WHR solution liquefied natural gas (LNG) fuelled transport truck. LNG being one less polluting fossil fuels widely spreading nowadays ...

The demand for liquified natural gas grows as it is an energy resource that has more flexible means of transport than non-liquefied gas, and eco-friendly other fossil fuels. This paper focused on comparing five different mixed-refrigerant liquefaction processes to determine which one the most efficient in energetic economic terms four processing scales (20,000 kg/h 2, 4, 8 MTPA feed). Simpler w...

In order to reduce global CO2 emissions, capture based on absorption in an amine/water mixture is established method. To develop such processes, correct physicochemical properties like densities and viscosities are important.The first objective of this work explore mathematical correlations for fitting viscosity data aqueous Monoethanolamine (MEA) Methyldiethanolamine (MDEA). A second evaluate ...

Development and change in forest communities are strongly influenced by plant-soil interactions. The primary objective of this paper was to identify how forest soil characteristics vary along gradients of forest community composition in aspen-conifer forests to better understand the relationship between forest vegetation characteristics and soil processes. The study was conducted on the Fishlak...