Showing papers by "Michigan Technological University published in 2003"

Particle-turbulence interactions in atmospheric clouds

Abstract: ▪ Abstract Turbulence is ubiquitous in atmospheric clouds, which have enormous turbulence Reynolds numbers owing to the large range of spatial scales present. Indeed, the ratio of energy-containing and dissipative length scales is on the order of 105 for a typical convective cloud, with a corresponding large-eddy Reynolds number on the order of 106 to 107. A characteristic trait of high-Reynolds-number turbulence is strong intermittency in energy dissipation, Lagrangian acceleration, and scalar gradients at small scales. Microscale properties of clouds are determined to a great extent by thermodynamic and fluid-mechanical interactions between droplets and the surrounding air, all of which take place at small spatial scales. Furthermore, these microscale properties of clouds affect the efficiency with which clouds produce rain as well as the nature of their interaction with atmospheric radiation and chemical species. It is expected, therefore, that fine-scale turbulence is of direct importance to the evolu...

Product modularity: Definitions and benefits

Abstract: The present paper presents an overview of existing research on the definition of modular product design and its benefits. Modularity has been discussed in terms of product development for quite some time. In recent years, the discussions have increased. The development of metrics and methods has also increased. However, these metrics and methods are often based on different definitions and varying goals. Understanding what modularity is and why it is useful is the foundation of modular product design. The purpose of this paper is to examine the existing literature and draw conclusions about where consensus exists and areas for further discussion. The relationship to product platform planning is also shown. This overview shows that there is a clear consensus on the point of independence of form and function. Within this definition, there is a strong pressure to extend modularity beyond form-function concerns and out across the life-cycle. Additionally, there is pressure to look at similarity or compatibili...

Sustainability Science and Engineering: The Emergence of a New Metadiscipline

Abstract: A case is made for growth of a new metadiscipline of sustainability science and engineering. This new field integrates industrial, social, and environmental processes in a global context. The skills required for this higher level discipline represent a metadisciplinary endeavor, combining information and insights across multiple disciplines and perspectives with the common goal of achieving a desired balance among economic, environmental, and societal objectives. Skills and capabilities that are required to support the new metadiscipline are summarized. Examples of integrative projects are discussed in the areas of sustainability metrics and integration of industrial, societal, and environmental impacts. It is clear that a focus on green engineering that employs pollution prevention and industrial ecology alone are not sufficient to achieve sustainability, because even systems with efficient material and energy use can overwhelm the carrying capacity of a region or lead to other socially unacceptable outcomes. To meet the educational and human resource needs required for this new discipline, the technological and environmental awareness of society must be elevated and a sufficient and diverse pool of human talent must be attracted to this discipline.

Classification scheme for lean manufacturing tools

Abstract: For the past few years almost every manufacturing industry has been trying to get 'lean'. A headlong rush to become lean also resulted in many misapplications of existing lean manufacturing tools often due to inadequate understanding of the purpose of tools. While tool descriptions abound, there is no way systematically to link a manufacturing organization to its problems and to the possible tools to eliminate these problems. The main purpose of this paper is to propose a classification scheme to serve as a link between manufacturing waste problems and lean manufacturing tools. A manufacturing organization can then match its manufacturing wastes with the appropriate lean manufacturing tools. The classification of existing knowledge is often the first step in moving from a practice to a science. This classification scheme systematically organizes lean manufacturing tools and metrics according to their level of abstraction, appropriate location of application of the tool in the organization, whether it addr...

Combinatorial modification of multiple lignin traits in trees through multigene cotransformation

Abstract: Lignin quantity and reactivity [which is associated with its syringyl/guaiacyl (S/G) constituent ratio] are two major barriers to wood-pulp production. To verify our contention that these traits are regulated by distinct monolignol biosynthesis genes, encoding 4-coumarate–CoA ligase (4CL) and coniferaldehyde 5-hydroxylase (CAld5H), we used Agrobacterium to cotransfer antisense 4CL and sense CAld5H genes into aspen (Populus tremuloides). Trees expressing each one and both of the transgenes were produced with high efficiency. Lignin reduction by as much as 40% with 14% cellulose augmentation was achieved in antisense 4CL plants; S/G-ratio increases as much as 3-fold were observed without lignin quantity change in sense CAld5H plants. Consistent with our contention, these effects were independent but additive, with plants expressing both transgenes having up to 52% less lignin, a 64% higher S/G ratio, and 30% more cellulose. An S/G-ratio increase also accelerated cell maturation in stem secondary xylem, pointing to a role for syringyl lignin moieties in coordinating xylem secondary wall biosynthesis. The results suggest that this multigene cotransfer system should be broadly useful for plant genetic engineering and functional genomics.

Spatial patterns of demography and genetic processes across the species' range: Null hypotheses for landscape conservation genetics

Abstract: Compared with populations near the core of aspecies' range, edge populations tend to becharacterized by low density and high temporalvariation. Based on empirical studiesquantifying this pattern, we show thateffective population size (Ne)could be 2 to 30 times greater near the coreof the species' range than near the edge ofthe range. Hence, the rate of genetic driftmay be 2 to 30 times greater near the edge ofthe range. Despite these strong spatialpatterns in Ne, empirical findingsindicate that peripheral populations sometimeshave less but sometimes have more geneticdiversity than core populations. Our analysisindicates that this variation can be explainedby uncertainty in spatial patterns ofmigration rates. Nevertheless, our analysis:(1) provides a framework or null hypothesis forempirically assessing how spatial patterns ofmigration or selection influence large-scalespatial patterns of genetic diversity, (2)highlights the potential importance ofcontemporary processes, such as spatialpatterns in Ne (cf. historicalphenomena, such as range expansion) in thedevelopment and maintenance of large-scalespatial patterns in genetic diversity, and (3) provides new context for understanding the conservation value and vulnerability of peripheralpopulations. The conservation ofecological/evolutionary processes requiresunderstanding large scale spatial patterns ofdemographic and genetic processes such as thatdescribed here.

Tropospheric O3 moderates responses of temperate hardwood forests to elevated CO2: a synthesis of molecular to ecosystem results from the Aspen FACE project

Abstract: Summary 1. The impacts of elevated atmospheric CO 2 and/or O 3 have been examined over 4 years using an open-air exposure system in an aggrading northern temperate forest containing two different functional groups (the indeterminate, pioneer, O 3 -sensitive species Trembling Aspen, Populus tremuloides and Paper Birch, Betula papyrifera , and the determinate, late successional, O 3 -tolerant species Sugar Maple, Acer saccharum ). 2. The responses to these interacting greenhouse gases have been remarkably consistent in pure Aspen stands and in mixed Aspen/Birch and Aspen/Maple stands, from leaf to ecosystem level, for O 3 -tolerant as well as O 3 -sensitive genotypes and across various trophic levels. These two gases act in opposing ways, and even at low concentrations (1·5 × ambient, with ambient averaging 34‐36 nL L − 1 during the summer daylight hours), O 3 offsets or moderates the responses induced by elevated CO 2 . 3. After 3 years of exposure to 560 µ mol mol − 1 CO 2 , the above-ground volume of Aspen stands was 40% above those grown at ambient CO 2 , and there was no indication of a diminishing growth trend. In contrast, O 3 at 1·5 × ambient completely offset the growth enhancement by CO 2 , both for O 3 -sensitive and O 3 -tolerant clones. Implications of this finding for carbon sequestration, plantations to reduce excess CO 2 , and global models of forest productivity and climate change are presented.

Coupling fine root dynamics with ecosystem carbon cycling in black spruce forests of interior Alaska

Abstract: Fine root processes play a prominent role in the carbon and nutrient cycling of boreal ecosystems due to the high proportion of biomass allocated belowground and the rapid decomposition of fine roots relative to aboveground tissues. To examine these issues in detail, major components of ecosystem carbon flux were studied in three mature black spruce forests in interior Alaska, where fine root production, respiration, mortality and decomposition, and aboveground production of trees, shrubs, and mosses were measured relative to soil CO2 fluxes. Fine root production, measured over a two-year period using minirhizotrons, varied from 0.004 ± 0.001 mm·cm–2·d–1 over winter, to 0.051 ± 0.015 mm·cm–2·d–1 during July, with peak growing season values comparable to those reported for many temperate forests using similar methods. On average, 84% of this production occurred within 20 cm of the moss surface, although the proportion occurring in deeper profiles increased as soils gradually warmed throughout the summer. M...

Effects of Forest Roads on Understory Plants in a Managed Hardwood Landscape

Abstract: The effect of forest roads on species distribution and dispersal is an important conservation and management issue. We examined distributions of understory plants and their relationships to unpaved forest roads in a northern hardwood landscape in the Chequamegon National Forest, Wisconsin (U.S.A.). At six dif- ferent sites, we recorded species cover, canopy cover, litter depth and cover, and bare ground at 11 distances (0, 5, 10, 15, 20, 30, 45, 60, 90, 120, and 150 m) from the road edge. At each of the 11 distances, we estab- lished a 60-m transect parallel to the road edge, within which we sampled 10 randomly placed 1 � 1 m plots (660 plots). We examined changes in species abundance (percent species cover per plot), richness, and Shan- non-Wiener diversity ( H � ) with distance from the roads in an effort to determine the degree and magnitude of road effects on plant distribution. The species richness and Hof native plants and the abundance of exotic species were clearly related to distance from the roads. Exotic species were most prevalent within 15 m of roads, occurring infrequently in the interior forest. The richness and Hof native species were lower on the roadsides but reached interior-forest levels within a short distance (5 m) from the roads. The roads appeared to be associated with a disturbance corridor that affected site variables up to 15 m into the hardwood stands. At our six sites we detected 117 species, 25% of which occurred more frequently near the road, with only 12% having a 90% or greater preference for the forest interior. Our results suggest that roads have associated ef- fects that alter interior-forest conditions and thus plant species composition and abundance; however, these effects are limited in depth of penetration into managed forests.

Assessing the Effects of Public Participation

Abstract: This article presents the results of research designed to test participatory democracy assertions that high-quality public participation can affect participants' beliefs in desirable ways. It examines the relationships between exposure to quality participation and participant beliefs about the trustworthiness and responsiveness of a public agency and the value of including different viewpoints in public meetings. After participation in quality project meetings, participants were significantly more likely to believe the agency was responsive to public concerns. The results indicate that some specific aspects of quality participation are positively associated with expectations about the agency's responsiveness and performance. Positive associations were also found with tolerance for differences of opinion. These results have important implications for public administrators and theorists of participatory democracy.

Asian Outflow and Trans-Pacific Transport of Carbon Monoxide and Ozone Pollution: An Integrated Satellite, Aircraft, and Model Perspective

Abstract: Satellite observations of carbon monoxide (CO) from the Measurements of Pollution in the Troposphere (MOPITT) instrument are combined with measurements from the Transport and Chemical Evolution Over the Pacific (TRACE-P) aircraft mission over the northwest Pacific and with a global three-dimensional chemical transport model (GEOS-CHEM) to quantify Asian pollution outflow and its trans-Pacific transport during spring 2001. Global CO column distributions in MOPITT and GEOS-CHEM are highly correlated (R(exp 2) = 0.87), with no significant model bias. The largest regional bias is over Southeast Asia, where the model is 18% too high. A 60% decrease of regional biomass burning emissions in the model (to 39 Tg/yr) would correct the discrepancy; this result is consistent with TRACE-P observations. MOPITT and TRACE-P also give consistent constraints on the Chinese source of CO from fuel combustion (181 Tg CO/yr). Four major events of trans-Pacific transport of Asian pollution in spring 2001 were seen by MOPITT, in situ platforms, and GEOS-CHEM. One of them was sampled by TRACE-P (26-27 February) as a succession of pollution layers over the northeast Pacific. These layers all originated from one single event of Asian outflow that split into northern and southern plumes over the central Pacific. The northern plume (sampled at 6-8 km off California) had no ozone enhancement. The southern subsiding plume (sampled at 2-4 km west of Hawaii) contained a 8 - 17 ppbv ozone enhancement, driven by decomposition of peroxyacetylnitrate (PAN) to nitrogen oxides (NOx). This result suggests that PAN decomposition in trans-Pacific pollution plumes subsiding over the United States could lead to significant enhancements of surface ozone.

Quantitative shape measurements of distal volcanic ash

Abstract: [1] Large-scale volcanic eruptions produce fine ash (<200 μm) which has a long atmospheric residence time (1 hour or more) and can be transported great distances from the volcanic source, thus, becoming a hazard to aircraft and public health Ash particles have irregular shapes, so data on particle shape, size, and terminal velocities are needed to understand how the irregular-shaped particles affect transport processes and radiative transfer measurements In this study, a methodology was developed to characterize particle shapes, sizes, and terminal velocities for three ash samples of different compositions The shape and size of 2500 particles from (1) distal fallout (∼100 km) of the 14 October 1974 Fuego eruption (basaltic), (2) the secondary maxima (∼250 km) of the 18 August 1992 Spurr eruption (andesitic), and (3) the Miocene Ash Hollow member, Nebraska (rhyolitic) were measured using image analysis techniques Samples were sorted into 10 to 19 terminal velocity groups (06–590 cm/s) using an air elutriation device Grain-size distributions for the samples were measured using laser diffraction Aspect ratio, feret diameter, and perimeter measurements were found to be the most useful descriptors of how particle shape affects terminal velocity These measurement values show particle shape differs greatly from a sphere (commonly used in models and algorithms) The diameters of ash particles were 10–120% larger than ideal spheres at the same terminal velocity, indicating that irregular particle shape greatly increases drag Gas-adsorption derived surface areas are 1 to 2 orders of magnitude higher than calculated surface areas based on measured dimensions and simple geometry, indicating that particle shapes are highly irregular Correction factors for surface area were derived from the ash sample measurements so that surface areas calculated by assuming spherical particle shapes can be corrected to reflect more realistic values

A review of binders in iron ore pelletization

Abstract: The majority of iron ores must be ground to a fine particle size to allow the iron oxides they contain to be concentrated, and the concentrate must then be agglomerated back into large enough particles that they can be processed in blast furnaces. The most common agglomeration technique is pelletization, which requires the use of binders to hold the iron oxide grains together so that the agglomerates can be sintered into high-strength pellets. Although bentonite clay is the most commonly used binder, there are many other possibilities that could be competitive in a number of situations. This article reviews the numerous types of binders (both organic and inorganic) that have been considered for iron ore pelletization, including discussion of the binding mechanisms, advantages and limitations of each type, and presentation of actual pelletization results, so that the performance of the various types of binders can be compared and evaluated.

Temporal trends in lava dome extrusion at Santiaguito 1922–2000

Abstract: We present a means of extracting lava dome extrusion rates from data provided by the Thematic Mapper and Enhanced Thematic Mapper Plus instruments flown on the Landsat satellites Extrusion rates derived from the Landsat data for Santiaguito dome complex (Guatemala) during November 1987 and January 2000 of 072±008 and 048±009 m3 s–1 compare favorably with ground-based estimates of 063±028 and 048±017 m3 s–1 A satellite-data-derived set of 18 extrusion rate estimates between 1987 and 2000, along with ground-based volume estimates prior to 1987, allow us to infer volumes of magma erupted since 1922 These data reveal cyclic extrusion at Santiaguito Each cycle begins with a 3–6-year-long phase of high extrusion rate (05–21 m3 s–1), followed by a longer (3–11 years) phase of low extrusion rate (≤02 m3 s–1) The 8th cycle began in 1996 and was still in its high extrusion rate phase during January 2000 With time, however, the durations of the low extrusion rate phases have increased, peak extrusion and time-averaged extrusion rates for each cycle have decreased, and the difference between extrusion rates during the high and low extrusion rate phases of each cycle has decreased These trends may be the result of depressurization and exhaustion of the source In this case, the current eruption may be expected to end around 2020 Alternatively, Santiaguito may be entering a period of persistent activity maintained by a stable magma supply In this case, we may expect extrusion to become less cyclic and to stabilize at 02–04 m3 s–1 However, a 2 wt% decrease in SiO2 content of erupted products since 1970 appears to be consistent with chamber exhaustion, as well as an increase in block lava flow lengths during 1970–2000

Study of Interspacecraft Coulomb Forces and Implications for Formation Flying

Abstract: In the course of exploiting spacecraft formations for use in separated interferometry (or other missions), it is possible that the separation distance between vehicles will be on the order of 10 m. The effects of spacecraft charging on the dynamics of very closely spaced formations are investigated. For certain high-Earth orbits, the ambient plasma conditions will conspire to produce significant spacecraft charging in an environment with a plasma Debye length of more than 100 m. For such conditions, it is shown that the potential exists to develop disruptive interspacecraft Coulomb forces and torques, with magnitude comparable to candidate formation-keeping thrusters over distances of tens of meters. Because of the unexpectedly large interaction forces, the concept of purposely charging spacecraft to affect formation-keeping Coulomb forces is also explored. Analytic methods are developed that show the existence of static equilibrium formations in Earth orbit using only inter-vehicle coulomb forces for one-, two-, and three-dimensional formations. Such Coulomb formations would be free of the risk of plume contamination due to thrusters firing in close proximity. Figures of merit for the proposed Coulomb control system are calculated in a manner analogous to traditional propulsion systems, and it is shown that required forces can be created with milliwatts of power, can be controlled on a millisecond timescale, and imply specific impulses that can be as high as 1013 seconds.

Foam extrusion of high density polyethylene/wood-flour composites using chemical foaming agents

Abstract: A one-way analysis of variance and thermal analysis were performed in this study to examine the influences of the contents, types (exothermic vs. endothermic), and forms (pure vs. masterbatch) of chemical foaming agents (CFAs), as well as the use of coupling agents, on the density reduction (or void fraction) and cell morphology of extrusion-foamed neat high density polyethylene (HDPE) and HDPE/wood-flour composites. The CFA types and forms did not affect the void fractions of both the neat HDPE and HDPE/wood-flour composites. However, a gas containment limit was observed for neat HDPE foams whereas the average cell size achieved in the HDPE/wood-flour composite foams remained insensitive to the CFA contents, irrespective of the foaming agent types. The experimental results indicated that the use of coupling agent in the formulation was required to achieve HDPE/wood-flour composite foams with high void fraction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3139–3150, 2003

Surface of cellulosic materials modified with functionalized polyethylene coupling agents

Abstract: The interfacial adhesion between a wood fiber and a plastic matrix strongly influences the performance of wood-fiber-reinforced thermoplastic composites. Fiber surface modification with coupling agents is generally needed to induce bond formation between the fiber and polymer matrix. This study investigated the chemical reactions between cellulosic materials and functionalized polyethylene coupling agents. Both wood flour and cotton cellulose powder were treated with acrylic acid-functionalized polyethylene and maleic anhydride-functionalized polyethylene (maleated polyethylene) for surface modifications, and chemical changes resulting from these treatments were followed by a study of the Fourier transform infrared and X-ray photoelectron spectroscopy spectra. Variations in the band intensities, oxygen-to-carbon ratios, and concentrations of unoxidized carbon atoms were related to changes that occurred on the surfaces of modified cellulosic materials. The experimental results indicated that chemical bonds between the hydroxyl groups of the cellulosic materials and the functional groups of the coupling agents occurred through esterification reactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 278–286, 2003

Reduction of soil carbon formation by tropospheric ozone under increased carbon dioxide levels

Abstract: In the Northern Hemisphere, ozone levels in the troposphere have increased by 35 per cent over the past century, with detrimental impacts on forest and agricultural productivity, even when forest productivity has been stimulated by increased carbon dioxide levels. In addition to reducing productivity, increased tropospheric ozone levels could alter terrestrial carbon cycling by lowering the quantity and quality of carbon inputs to soils. However, the influence of elevated ozone levels on soil carbon formation and decomposition are unknown. Here we examine the effects of elevated ozone levels on the formation rates of total and decay-resistant acid-insoluble soil carbon under conditions of elevated carbon dioxide levels in experimental aspen (Populus tremuloides) stands and mixed aspen-birch (Betula papyrifera) stands. With ambient concentrations of ozone and carbon dioxide both raised by 50 per cent, we find that the formation rates of total and acid-insoluble soil carbon are reduced by 50 per cent relative to the amounts entering the soil when the forests were exposed to increased carbon dioxide alone. Our results suggest that, in a world with elevated atmospheric carbon dioxide concentrations, global-scale reductions in plant productivity due to elevated ozone levels will also lower soil carbon formation rates significantly.

Effectiveness of Maleated and Acrylic Acid-Functionalized Polyolefin Coupling Agents for HDPE-Wood-Flour Composites:

Abstract: The performance of fiber reinforced thermoplastic composites strongly depends on solid fiber-matrix adhesion to allow stress transfer between the phases. Fiber surface modification with coupling agents is generally needed to induce bond formation between the fiber and the polymer. This study investigated the effects of coupling agent's functional monomer (acrylic acid vs. maleic anhydride) and base resin (polyethylene (PE) vs. polypropylene (PP)) types on the tensile and flexural properties of high-density polyethylene (HDPE)-wood-flour composites. The interfacial adhesion between wood flour and HDPE matrix was examined using environmental scanning electron microscope. The experimental results indicate that the types of functional monomer and base resin are important factors determining the effectiveness of functionalized coupling agents for HDPE-wood-flour composites. Maleic anhydride-functionalized polyolefins perform better than acrylic acid counterparts whereas PE-based maleated coupling agents are mo...

Industrial applications using BASF eco-efficiency analysis: perspectives on green engineering principles.

Abstract: Life without chemicals would be inconceivable, but the potential risks and impacts to the environment associated with chemical production and chemical products are viewed critically. Eco-efficiency analysis considers the economic and life cycle environmental effects of a product or process, giving these equal weighting. The major elements of the environmental assessment include primary energy use, raw materials utilization, emissions to all media, toxicity, safety risk, and land use. The relevance of each environmental category and also for the economic versus the environmental impacts is evaluated using national emissions and economic data. The eco-efficiency analysis method of BASF is briefly presented, and results from three applications to chemical processes and products are summarized. Through these applications, the eco-efficiency analyses mostly confirm the 12 Principles listed in Anastas and Zimmerman (Environ. Sci. Technol. 2003, 37(5), 94A), with the exception that, in one application, production systems based on bio-based feedstocks were not the most eco-efficient as compared to those based on fossil resources. Over 180 eco-efficiency analyses have been conducted at BASF, and their results have been used to support strategic decision-making, marketing, research and development, and communication with external parties. Eco-efficiency analysis, as one important strategy and success factor in sustainable development, will continue to be a very strong operational tool at BASF.

Volcanic eruption detection by the Total Ozone Mapping Spectrometer (TOMS) instruments: a 22-year record of sulphur dioxide and ash emissions

Abstract: * Joint Center for Earth Systems Technology (NASA/UMBC), University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21231, USA. Email: scarn@umbc.edu † Department of Geological Engineering and Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA. ‡ Goddard Earth Sciences and Technology (GEST) Center, Code 916, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.