Comparison of near-field mixing zone models for multiport diffusers in the Great Lakes

1994 ◽  
Vol 21 (1) ◽  
pp. 141-155 ◽  
Author(s):  
I.K. Tsanis ◽  
C. Valeo ◽  
Y. Diao
Keyword(s):  
Great Lakes ◽  
Environmental Protection Agency ◽  
Near Field ◽  
Laboratory Data ◽  
Field Studies ◽  
Mixing Zone ◽  
Initial Dilution ◽  
Wake Effects ◽  
Guidelines And Recommendations ◽  
Field Behaviour

This paper presents a review of near-field mixing zone models and compares their performance with common outfall diffuser examples in the Great Lakes. The results of initial dilutions for three types of multiport diffusers, based on the Ontario Ministry of Environment (MOE) guidelines and recommendations, are compared with those calculated by using the U.S. Environmental Protection Agency (EPA) models. These models include five integral-type models (UPLUME, UOUTPLM, UDKHDEN, UMERGE, and ULINE) and a "length scale" type expert system (CORMIX2). Results based on the first four EPA integral models give higher initial dilutions when compared to results based on CORMIX2 and the MOE guidelines, ULINE gives unrealistically low dilutions. Excluding UPLUME, the initial dilutions given by the other EPA models increase with increasing ambient current. Alternating diffusers generally give lower initial dilutions than the staged and unidirectional diffusers, while unidirectional diffusers produce the highest of the three. Results from the computation tests based on the mixing models can aid in more reasonable and economical diffuser designs that still meet the requirement of initial dilution criteria. While all the models selected for this study have limitations, CORMIX2 is preferred for most Great Lakes applications. It can be applied to all four types of multiport diffusers and can handle different types of ambient stratification, bottom and shore attachment, wake effects and dead zones, plume trapping and far-field behaviour. CORMIX2 predictions compare well with laboratory data and very limited field data. Given the complexity of the problem, more field studies should be performed for further validation of the models. Key words: mixing zone, multiport diffusers, initial dilution.

Cormix: An Expert System for Mixing Zone Analysis

1991 ◽  
Vol 24 (6) ◽  
pp. 267-274 ◽  
Author(s):  
G. H. Jirka ◽  
R. L. Doneker ◽  
T. O. Barnwell
Keyword(s):  
Expert System ◽  
Current Practice ◽  
Classification Scheme ◽  
Near Field ◽  
Limited Area ◽  
Mixing Zone ◽  
Analysis And Design ◽  
Initial Dilution ◽  
Surface Discharges ◽  
Quality Policy

United States water quality policy includes the concept of a mixing zone, a limited area where initial dilution of a discharge occurs. Current practice in mixing zone analysis is plagued by a number of problems --mixing zone definitions vary widely; there is a diversity of discharge and site conditions; existing models focus on near-field mixing while legal definitions extend to greater distances; and there are a large number of permitting applications needing review. The Cornell Mixing Zone Expert System (CORMIX) is a series of software elements for analysis and design of submerged buoyant or nonbuoyant discharges containing conventional or toxic pollutants into stratified or unstratified waters, with emphasis on the geometry and dilution characteristics of the initial mixing zone. Subsystem CORMIX1 deals with single port discharges, CORMIX2 addresses multiport diffusers, and subsystem CORMIX3 analyzes surface discharges. The software is implemented on microcomputers using the MS-DOS operating system. It contains two key elements -- 1) a rigorous flow classification scheme that analyzes the near-field behavior of a discharge and 2), a collection of predictive elements for each discharge scenario. This paper describes the development philosophy underlining CORMIX, the capabilities of the three subsystems, and describes the procedure for obtaining the software.

The impact of leaf shape on the feeding preference of insect herbivores: experimental and field studies with Capsella and Phyllotreta

1996 ◽  
Vol 351 (1348) ◽  
pp. 1671-1677 ◽  
Keyword(s):  
Leaf Shape ◽  
Laboratory Data ◽  
Leaf Size ◽  
Field Studies ◽  
Feeding Preference ◽  
Insect Herbivores ◽  
Flea Beetles ◽  
Shape Effects ◽  
Leaf Size And Shape ◽  
The Impact

Leaves display an enormous array of sizes and shapes. Although these attributes appear to have evolved primarily in response to abiotic conditions in the plant’s habitat, the importance of insect herbivores as additional selective agents is still poorly understood. A necessary requirem ent for leaf size and shape to evolve in response to attack by insects is that insects must respond to and/or be affected by, leaf morphology. We tested leaf-shape preferences in adult flea beetles ( Phyllotreta spp.) feeding on the highly variable rosette leaves of Capsella bursa-pastoris . Contrary to theoretical expectation (Brown & Lawton 1991), leaves with deeply lobed margins were more intensely damaged, both in field-collected and experimental plants. In two ancillary experiments with Capsella , we found that Spodoptera caterpillars showed no preferences for leaf shape, but that adult vine weevils ( Otiorhynchus sulcatus ) did, preferring (as predicted), undivided over divided leaves. We conclude that Brown & Law ton’s (1991) hypothesis is at best weakly supported by laboratory data for vine weevils, refuted by laboratory data for Spodoptera , and consistently refuted by both laboratory and field data for flea beetles. Although the experiment tried to reduce confounding variables to a minimum, interpretation was complicated by correlations between leaf shape and other developmental parameters of the plants, and highlights the difficulty of disentangling leaf-shape effects from other confounding factors.

scholarly journals Legume Cover Crop Effects on Temperate Sugarcane Yields and Their Decomposition in Soil

Agronomy ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 703
Author(s):  
Paul M. White ◽  
Gregory Williams ◽  
Howard P. Viator ◽  
Ryan P. Viator ◽  
Charles L. Webber
Keyword(s):  
Cover Crops ◽  
Cultural Practices ◽  
Laboratory Data ◽  
Field Studies ◽  
Mineral N ◽  
The Us ◽  
Legume Cover Crops ◽  
Different Temperatures ◽  
Sunn Hemp ◽  
Legume Cover Crop

Sugarcane is commercially produced on 340,000 ha in the US and is valued at over $1 billion US annually. Cultural practices that improve sugarcane sustainability are needed to maintain yields in fields with degraded soils. Historically, leguminous rotation crops provided organic matter and biologically fixed nitrogen (N) for subsequent sugarcane crops. Currently, sugarcane is usually grown as a monoculture with only a short, 6-month fallow period. The objective of these field studies was to determine how growing cowpea (Vigna unguiculata (L.) Walp.) and sunn hemp (Crotalaria juncea L.) as cover crops during fallow affected the yield of subsequent sugarcane crops. A companion laboratory study investigated the decomposition rate of cover crops in soil at different temperatures. Cowpea and sunn hemp production produced 12.8 t/ha dry matter and 250 kg N/ha. Cowpea generally improved plant cane yields, but the effects of sunn hemp varied. However, neither cowpea nor sunn hemp reduced cane or sucrose yields consistently, and mineral N additions may have a role in mitigating yield gains or losses. Based on laboratory data, the average half-life for cowpea and sunn hemp would be 3 months. Overall, using legume cover crops should be viewed as an important component of sustainable sugarcane practices.

Very Metal-Poor Stars and the Early Universe

2017 ◽  
Vol 13 (S334) ◽  
pp. 3-10
Author(s):  
John E. Norris
Keyword(s):  
Near Field ◽  
Field Studies ◽  
Far Field ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Physical Conditions ◽  
The Galaxy ◽  
Formation And Evolution ◽  
The Universe ◽  
Insight Into

AbstractVery metal-poor stars ([Fe/H] < –2.0) inform our understanding of the formation and evolution of the Galaxy, and the physical conditions in the earliest star-forming environments of the Universe. They play an integral part in the paradigms of stellar populations, stellar archaeology, and near-field cosmology. We review the carbon-rich and carbon-normal sub-populations of the most iron-poor stars, providing insight into chemical enrichment at the earliest times in the Universe. We also discuss the role of very metal-poor stars in providing insight into the Galaxy’s halo, thick disk, and bulge, and the promise they hold for the future. A comparison between the abundances obtained for the nine most Fe-poor stars ([Fe/H] < –4.5) (all but one of which is C-rich) with abundances obtained from far-field cosmology suggests that the former are the most chemically primitive objects yet observed and probably older than the DLA- and sub-DLA systems for which data are currently available from far-field studies.

Near-field studies of surface plasmon generation: optical and terahertz studies

2008 ◽  
Author(s):  
H. W. Kihm ◽  
K. G. Lee ◽  
M. A. Seo ◽  
K. J. Ahn ◽  
A. J. L. Adam ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
Near Field ◽  
Field Studies

Effects of castration on open-field behaviour and aggression in male meadow voles (Microtus pennsylvanicus)

1980 ◽  
Vol 58 (10) ◽  
pp. 1927-1932 ◽  
Author(s):  
Brian N. Turner ◽  
Stuart L. Iverson ◽  
Kenneth L. Severson
Keyword(s):  
Open Field ◽  
Field Studies ◽  
Intact Male ◽  
Intermale Aggression ◽  
Meadow Voles ◽  
Hormone Levels ◽  
Significant Difference ◽  
Free Ranging ◽  
Field Behaviour ◽  
Open Field Behaviour

A series of three experiments tested the hypothesis that castration would result in altered open-field behaviour and aggression in male meadow voles. The open-field behaviour of laboratory-reared voles was not affected, and that of wild-captured laboratory-housed animals showed only one significant difference. However, in free-ranging voles, recaptured at intervals for testing, castration resulted in significantly reduced intermale aggression, and significantly decreased activity and increased urination in the open field. Thus, only the results from the experiment using free-ranging voles indicate a significant castration effect, and we suggest the lack of effect in laboratory-housed animals may be due to changes in factors including photoperiod, social milieu, and season.The changes in aggression and open-field behaviour in the wild animals are in agreement with interpretation of previous field studies of intact male voles, which demonstrated changes in these two behaviours at the onset of the breeding season. Among free-ranging meadow voles, therefore, the decreased hormone levels resulting from castration led to changes in these behaviours opposite to those observed in the spring when hormone levels increase with seasonal reproductive maturity. These behaviours thus appear to be at least partially dependent upon circulating testosterone levels in wild voles.

scholarly journals Optical and terahertz near-field studies of surface plasmons in subwavelength metallic slits

2008 ◽  
Vol 10 (10) ◽  
pp. 105003 ◽  
Author(s):  
K J Ahn ◽  
K G Lee ◽  
H W Kihm ◽  
M A Seo ◽  
A J L Adam ◽  
...  
Keyword(s):  
Surface Plasmons ◽  
Near Field ◽  
Field Studies

scholarly journals Secondary‐ion‐mass spectrometry and near‐field studies of Ti:LiNbO3optical waveguides

1995 ◽  
Vol 78 (9) ◽  
pp. 5345-5350 ◽  
Author(s):  
F. Caccavale ◽  
P. Chakraborty ◽  
A. Quaranta ◽  
I. Mansour ◽  
G. Gianello ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Near Field ◽  
Field Studies ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

scholarly journals Modeling the Transport and Fate of Sediments Released from Marine Construction Projects in the Coastal Waters of British Columbia, Canada

2018 ◽  
Author(s):  
David B. Fissel ◽  
Yuehua Lin
Keyword(s):  
British Columbia ◽  
Numerical Methods ◽  
Environmental Assessment ◽  
Coastal Waters ◽  
Construction Projects ◽  
Numerical Models ◽  
Near Field ◽  
Suspended Sediments ◽  
Initial Dilution ◽  
Resolution Model

Major marine construction projects, resulting in the release of sediments, are subject to environmental assessment and other regulatory approval processes. An important tool used for this is the development of specialized numerical methods for these marine activities. An integrated set of numerical methods addresses four distinct topics: the near-field release and mixing of suspended sediments into the water column (i.e. the initial dilution zone); the transport of the suspended sediments under the influence of complex ocean currents in the far-field; the settling of the transported suspended sediments onto the seabed; and the potential for resuspension of the deposited sediments due to sporadic occurrences of unusually large near-bottom currents. A review of projects subjected to environmental assessment in the coastal waters of British Columbia from the year 2006 to 2017, is presented to illustrate the numerical models being used and their ongoing development. Improvements include higher resolution model grids to better represent the near-field, the depiction of particle size dependent vertical settling rates and the computation of resuspension of initially deposited sediments, especially in relation to temporary subsea piles of sediments arising from trenching for marine pipelines. The ongoing challenges for this numerical modeling application area are also identified.

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