10,791 research outputs found
Dry anaerobic digestion of organic waste: A review of operational parameters and their impact on process performance.
open access articleDry digestion is a suitable technology for treating organic wastes with varying composition such as the organic
fraction of municipal solids waste. Yet, there is a need for further research to overcome some of the disadvantages
associated with the high total solids content of the process. Optimisation of inoculum to substrate
ratio, feedstock composition and size, liquid recirculation, bed compaction and use of bulking agents are some of
the parameters that need further investigation in batch dry anaerobic digestion, to limit localised inhibition
effects and avoid process instability. In addition, further attention on the relation between feedstock composition,
organic loading rate and mixing regimes is required for continuous dry anaerobic digestion systems. This
paper highlights all the areas where knowledge is scarce and value can be added to increase dry anaerobic
digestion performance and expansion
TB6: Importance of Entomogenous Fungi in Controlling Aphids on Potatoes in Northeastern Maine
This publication reports on field studies of aphid biology and of associated ecological factors made near Presque Isle, Maine. Results showed that, among the biological agents affecting aphid population trends from 1952 through 1962, entomogenous fungi were outstanding in reducing the size of populations of the potato aphid developing on potatoes treated with fungicides but not with insecticides. The potato aphid was most affected by fungi and the buckthorn aphid least affected by them. The green peach and foxglove aphids were intermediate. Predators exerted a noticeably adverse effect upon aphid population trends in two of the 11 years.https://digitalcommons.library.umaine.edu/aes_techbulletin/1188/thumbnail.jp
Shrinking Point Bifurcations of Resonance Tongues for Piecewise-Smooth, Continuous Maps
Resonance tongues are mode-locking regions of parameter space in which stable
periodic solutions occur; they commonly occur, for example, near Neimark-Sacker
bifurcations. For piecewise-smooth, continuous maps these tongues typically
have a distinctive lens-chain (or sausage) shape in two-parameter bifurcation
diagrams. We give a symbolic description of a class of "rotational" periodic
solutions that display lens-chain structures for a general -dimensional map.
We then unfold the codimension-two, shrinking point bifurcation, where the
tongues have zero width. A number of codimension-one bifurcation curves emanate
from shrinking points and we determine those that form tongue boundaries.Comment: 27 pages, 6 figure
A simplified picture for Pi electrons in conjugated polymers : from PPP Hamiltonian to an effective molecular crystal approach
An excitonic method proper to study conjugated oligomers and polymers is
described and its applicability tested on the ground state and first excited
states of trans-polyacetylene, taken as a model. From the Pariser-Parr-Pople
Hamiltonian, we derive an effective Hamiltonian based on a local description of
the polymer in term of monomers; the relevant electronic configurations are
build on a small number of pertinent local excitations. The intuitive and
simple microscopic physical picture given by our model supplement recent
results, such as the Rice and Garstein ones. Depending of the parameters, the
linear absorption appears dominated by an intense excitonic peak.Comment: 41 Pages, 6 postscript figure
Robust chaos in orientation-reversing and non-invertible two-dimensional piecewise-linear maps
This paper concerns the two-dimensional border-collision normal form -- a
four-parameter family of piecewise-linear maps generalising the Lozi family and
relevant to diverse applications. The normal form was recently shown to exhibit
a chaotic attractor throughout an open region of parameter space. This was
achieved by constructing a trapping region in phase space and an invariant
expanding cone in tangent space, but only allowed parameter combinations for
which the normal form is invertible and orientation-preserving. This paper
generalises the construction to include the non-invertible and
orientation-reversing cases. This provides a more complete and unified picture
of robust chaos by revealing its presence to be disassociated from the global
topological properties of the map. We identify a region of parameter space in
which the map exhibits robust chaos, and show that part of the boundary of this
region consists of bifurcation points at which the chaotic attractor is
destroyed
TB58: Further Evaluation of Entomogenous Fungi as a Biological Agent of Aphid Control in Northeastern Maine
An intensive survey and study were made each year from 1952 through 1962 to determine seasonal abundance of living and dead diseased aphids by species on potatoes and to collect many of the infected specimens for exact diagnosis. Results of the study disclosed that the action of entomogenous fungi was outstanding in reducing the size of aphid populations on potatoes. This technical bulletin reports on the results of the continuance of the study from 1963 through 1969. However, the collection of dead, diseased aphids throughout the summer was done only from 1963 through 1966 ; thereafter, diagnosis was limited to dead, diseased specimens intensively collected from potatoes during a 1-week period when fungal activity was greatest. This was usually in mid-August, near the seasonal peak of aphid abundance on potatoes not treated with insecticides.https://digitalcommons.library.umaine.edu/aes_techbulletin/1131/thumbnail.jp
Chemical vapor deposition growth
A chemical vapor deposition (CVD) reactor system with a vertical deposition chamber was used for the growth of Si films on glass, glass-ceramic, and polycrystalline ceramic substrates. Silicon vapor was produced by pyrolysis of SiH4 in a H2 or He carrier gas. Preliminary deposition experiments with two of the available glasses were not encouraging. Moderately encouraging results, however, were obtained with fired polycrystalline alumina substrates, which were used for Si deposition at temperatures above 1,000 C. The surfaces of both the substrates and the films were characterized by X-ray diffraction, reflection electron diffraction, scanning electron microscopy optical microscopy, and surface profilometric techniques. Several experiments were conducted to establish baseline performance data for the reactor system, including temperature distributions on the sample pedestal, effects of carrier gas flow rate on temperature and film thickness, and Si film growth rate as a function of temperature
Aircraft requirements for low/medium density markets
A study was conducted to determine the demand for and the economic factors involved in air transportation in a low and medium density market. The subjects investigated are as follows: (1) industry and market structure, (2) aircraft analysis, (3) economic analysis, (4) field surveys, and (5) computer network analysis. Graphs are included to show the economic requirements and the aircraft performance characteristics
Livestock Producers and Researchers - A Case Study of an Effective Partnership
The Sustainable Grazing Systems Programme (SGS) ran from 1996-2002 with 11 regional producer committees (Regional Producer Network - Simpson et al., 2003) and 6 research sites (National Experiment Andrew & Lodge, 2003) distributed throughout the high rainfall zone of temperate Australia. Each regional committee had a core of producers, with invited scientists and extension practitioners and a paid facilitator. The chair was always a producer and rotated annually. Each regional committee conducted a number of paddock-sized demonstrations of improved grazing management practices on a number of farms within the themes; grazing management and weeds, high input systems, innovative grazing methods for production and the SGS adoption process. Each demonstration was on a producer\u27s property assisted by a local management committee with objective data collected by the regional facilitator. The National research sites investigated the effects of grazing management on sustainable livestock production through five themes; water, nutrients, pastures, animals and biodiversity. Producers had a significant input into the design of the National Experiment and each site had a local advisory committee
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