The effects of Venus' thermal structure on buoyant magma ascent

The recent Magellan images have revealed a broad spatial distribution of surface volcanism on Venus. Previous work in modeling the ascent of magma on both Venus and Earth has indicated that the planetary thermal structure significantly influences the magmatic cooling rates and thus the amount of magma that can be transported to the surface before solidification. In order to understand which aspects of the thermal structure have the greatest influence on the cooling of ascending magma, we have constructed magma cooling curves for both plutonic and crack buoyant ascent mechanisms, and evaluated the curves for variations in the planetary mantle temperature, thermal gradient curvature with depth, surface temperature gradient, and surface temperature. The planetary thermal structure is modeled as T/T(sub 0) = 1-tau(1-Z/Z(sub 0)(exp n), where T is the temperature, T(sub 0) is the source depth temperature, tau = 1-(T(sub s)/T(sub 0)) where T(sub s) is the planetary surface temperature, Z is the depth, Z(sub 0) is the source depth, and n is a constant that controls thermal gradient curvature with depth. The equation is used both for mathematical convenience and flexibility, as well as its fit to the thermal gradients predicted by the cooling half-space models. We assume a constant velocity buoyant ascent, body-averaged magma temperatures and properties, an initially crystal-free magma, and the same liquidus and solidus for both Venus and Earth

Gate-to-Gate Life-Cycle Inventory of Softwood Plywood Production

A life-cycle inventory (LCI) study is conducted of softwood plywood manufacturing. This gate-to-gate study includes all materials, fuels, and electricity inputs to produce plywood, co-products and emissions. Data were collected through surveys of manufacturing facilities in the Pacific Northwest and the Southeast. SimaPro software, a program to conduct life-cycle inventory studies, is used to process the data and determine environmental impacts in terms of material use and emissions. The data are allocated on a mass basis to plywood based on their contribution to the mass sum of all product and co-products. All data are provided on a production unit basis of 1.0 m3 and 1.0 MSF 3/8-inch basis, the U.S. industry standard. In addition to LCI data, carbon flow data are also given. The LCI data are publicly available through reports, this publication, and the U.S. LCI Database Project. The data are useful for generating cradle-to-gate product LCIs when combined with the LCIs to produce logs for the mills and material transportation impacts, and are useful as a benchmark for assessing process performance, for conducting life-cycle analysis of wall, floor, and roof assemblies consisting of plywood and other products, and of residential structures

Life-cycle inventory of plywood manufacturing in the Pacific Northwest and the Southeast United States

Softwood plywood is one of the structural wood products studied in the CORRIM II effort to document the environmental performance of wood product in residential structures. Life-cycle inventory (LCI) models were developed to provide performance data for plywood production by tracking all of its inputs and outputs in a gate-to-gate analysis. The models divided the plywood process into the primary subunit processes of debarking and bucking, log conditioning, peeling and clipping of veneer, veneer drying, lay up and hot pressing of plywood, and trimming and sawing. A hogged fuel fired boiler process and a phenol formaldehyde production model were also included. Modeling plywood production with subunit processes provided detailed analysis of the operation and enabled optimization studies. Model inputs were electricity, fuel, and materials of wood in the form of logs and adhesive, while the outputs were plywood, wood co-products, and environmental emissions to the air, land and water. SimaPro, an environmental impact assessment software package, was used to analyze the data to provide an LCI. The study was done for two major wood producing regions of the United States - the Pacific Northwest and the Southeast. Various process scenarios were modeled, providing useful information such as a sensitivity of input parameters and an impact assessment of the type of fuel used to generate heat for processing. A carbon balance of wood used in plywood manufacturing was performed to compare the amount of carbon going into plywood production with the amount of carbon coming out as materials and emissions. Finally, a cost analysis was done to compare plywood production costs with the open market selling price of plywood. Electricity, fuel, and resin use contributed a significant amount of emissions in plywood production. Log conditioning, veneer drying, and panel pressing subunit process consumed more than half the electricity used (55%) and also used all the heat energy inputted into the process. The sensitivity analysis of switching fuel sources for heat energy indicated that natural gas used as a fuel input, resulted in higher greenhouse gases (CO2 (fossil), methane, NON, SON) emissions when compared to hogged fuel comprised of bark and wood waste. Hogged fuel used as a fuel resulted in less CO7 (fossil) emissions but increased in CO and phenol emissions (hazardous air pollutant) when compared to natural gas. A carbon balance documented all carbon material and compared the wood inputs with wood related outputs including plywood, co-products, air and solid emissions. The carbon balance can be used as a benchmark to continue research of the carbon cycle to reduce greenhouse gas, CO2. The model can be used as a tool in developing useful strategies for examining the consequences of process and equipment changes, and for optimizing the environmental performance of a process

Spatial and Alignment Analyses for a field of Small Volcanic Vents South of Pavonis Mons Mars

The Tharsis province of Mars displays a variety of small volcanic vent (10s krn in diameter) morphologies. These features were identified in Mariner and Viking images [1-4], and Mars Orbiter Laser Altimeter (MOLA) data show them to be more abundant than originally observed [5,6]. Recent studies are classifying their diverse morphologies [7-9]. Building on this work, we are mapping the location of small volcanic vents (small-vents) in the Tharsis province using MOLA, Thermal Emission Imaging System, and High Resolution Stereo Camera data [10]. Here we report on a preliminary study of the spatial and alignment relationships between small-vents south of Pavonis Mons, as determined by nearest neighbor and two-point azimuth statistical analyses. Terrestrial monogenetic volcanic fields display four fundamental characteristics: 1) recurrence rates of eruptions,2 ) vent abundance, 3) vent distribution, and 4) tectonic relationships [11]. While understanding recurrence rates typically requires field measurements, insight into vent abundance, distribution, and tectonic relationships can be established by mapping of remotely sensed data, and subsequent application of spatial statistical studies [11,12], the goal of which is to link the distribution of vents to causal processes