323,795 research outputs found
Swales, Ernest Beckwith, WX4018
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/420124Surname: SWALES. Given Name(s) or Initials: ERNEST BECKWITH. Military Service Number or Last Known Location: WX4018. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 30299.244705
Item: [2016.0049.52385] "Swales, Ernest Beckwith, WX4018
Swales, J F, 422989
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/420123Surname: SWALES. Given Name(s) or Initials: J F. Military Service Number or Last Known Location: 422989. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 57549.244704
Item: [2016.0049.52384] "Swales, J F, 422989
The performance enhancement of multibeam adaptive base-station antennas for cellular land mobile radio systems
No full textThe problem of meeting the proliferating demands for mobile telephony within the confinement of the limited radio spectrum allocated to these services is addressed. A multiple-beam adaptive base-station antenna is proposed as a major system component in an attempt to solve this problem. The approach is demonstrated by employing an antenna array capable of resolving the angular distribution of the mobile users as seen at the base-station site, and then using this information to direct beams toward either lone mobiles, or groupings of mobiles, for both transmit and receive modes of operation. The energy associated with each mobile is thus confined within the addressed volume, greatly reducing the amount of cochannel interference experienced from and by neighboring cochannel cells. To ascertain the benefits of such an antenna, the conventional and proposed antenna systems are modeled in a typical mobile radio environment. For a given performance criterion, the theoretical results indicate that a significant increase in the spectral efficiency, or capacity, of the network is obtainable with the proposed antenn
A Modified Manning’s Equation for Estimating Flow Rate in Grass Swales under Low Inflow Rate Conditions
No full textAs green infrastructure has evolved, grass swales have become integral components of stormwater management. Manning’s equation is commonly used to describe the hydraulic characteristics of grass swales. However, due to flow loss from infiltration, grass swales often deviate from the assumptions of Manning’s equation, potentially leading to significant errors in grass swale flow rate calculations. In this study, we systematically investigated changes in flow rates in grass swales under various constant inflow rate conditions. The results indicated that the suitability of using Manning’s equation to estimate flow rate in grass swales varies with inflow rate. At an inflow rate of 3.00 m3/h, the discrepancy between the measured and the estimated flow rates by Manning’s equation was the smallest, ranging from −0.24 to 0.19 m3/h. At lower inflow rates (1.00 to 2.00 m3/h), Manning’s equation underestimated the flow rates by 0.16 to 0.47 m3/h; at higher rates (4.00 m3/h), it overestimated the flow rates by 0.01 to 0.61 m3/h. Considering infiltration losses as the primary cause of these errors, we proposed an improved Darcy’s formula for estimating the infiltration rates in grass swales, along with a modified Manning’s equation for more accurate flow rate calculations. The modified Manning’s equation provides enhanced accuracy in calculating flow rates in grass swales compared to the traditional version
Assessing and Improving Pollution Prevention by Swales
No full textRoadside swales are drainage ditches that also treat runoff to improve water quality, including infiltration of water
to reduce pollutant load. In the infiltration study, a quick and simple device, the Modified Philip Dunne (MPD)
infiltrometer, was utilized to measure an important infiltration parameter (saturated hydraulic conductivity, Ksat) at
multiple locations in a number of swales. The study showed that the spatial variability in the swale infiltration rate
was substantial, requiring 20 or more measurements along the highway to get a good estimate of the mean swale
infiltration rate. This study also developed a ditch check filtration system that can be installed in swales to provide
significant treatment of dissolved heavy metals and dissolved phosphorous in stormwater runoff. The results were
utilized to develop design guidelines and recommendations, including sizing and treatment criteria for optimal
performance of the full-scale design of these filters. Finally, the best available knowledge on swale maintenance
was combined with information obtained from new surveys conducted to develop recommendations for swale
maintenance schedules and effort. The recommendations aim toward optimizing the cost-effectiveness of roadside
swales and thus provide useful information to managers and practitioners of roadways. The research results and
information obtained from this study can thus be used to design swale systems for use along linear roadway
projects that will receive pollution prevention credits for infiltration. This will enable the utilization of drainage
ditches to their full pollution prevention potential, before building other more expensive stormwater treatment
practices throughout Minnesota and the United States.Gulliver, John S.; Ahmed, Farzana; Natarajan, Poornima; Weiss, Peter T.; Nieber, John L.. (2014). Assessing and Improving Pollution Prevention by Swales. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/169458
Regression trend lines of ridges and swales on the emergent beach at Gisborne, New Zealand
No full textThe emergent sand-beach system at Gisborne consists of six recognisable groups of ridges and swales. It is about three miles wide and four miles long and rises gradually from 15ft above sea level at the coast to 40ft inland. From time to time the emergent beach has been mantled with air-borne volcanic ash including ash beds of the Waimihia Lapilli, Taupo Sub-group Members 9 - 13, Taupo Pumice, and Kaharoa Ash Formations. As the dates of these eruptions are known, the times of formation of the groups of beach ridges and wales have been determined as follows:
Group 1: c. 9000 B.C. - c. 1400 B.C.
Group 2: c. 1400 B.C. - (?) 850 B.C.
Group 3: (?) 850 B.C. - c. A.D. 131
Group 4: c. A.D. 131 - c. A.D. 1020
Group 5: c. A.D. 1020 - c. A.D. 1650
Group 6: c. A.D. 1650 - A.D. 1956
Evidence of recent earth movements has been noted in ridges and swales of Group 1, and of possible movements in those of Group 3. Changes in sea level could not be established and were taken from Wellman and Schofield. No attempt was made to distinguish directly wind-blown sand from wave-deposited sand; instead, a shell layer (assumed to be associated with the intertidal strand) was used as a marker bed to indicate the approximate sea level at the time when the shells were deposited.
Elevations of ridges and swales in each group were measured on a 15,000ft transect across the beach system. Then, overall linear and quadratic regressions as well as linear regressions for each group separately were computed. For both of the overall linear and quadratic regressions the trend lines show a fall seaward, but the separate trend lines for each group are as follows:
Group 1: Highly significant seaward decline.
Groups 2 and 3 combined: Very highly significant seaward decline.
Group 4: Highly significant seaward incline.
Groups 5 and 6 combined: No significant change.
The departure of the regression trend lines within Groups 1 to 6 from the overall linear and quadratic trend lines suggests that the trends of elevation across the emergent beach at Gisborne should be regarded more as a series of discontinuous trends rather than as one overall continuous trend of seaward decline. Though the overall trend of declining elevation is seaward, the corresponding fall in sea level is likely to be more apparent than real because of compounding of fall in sea level with earth movements
Assessing and Improving Pollution Prevention by Swales
No full textRoadside swales are drainage ditches that also treat runoff to improve water quality, including infiltration of water to reduce pollutant load. In the infiltration study, a quick and simple device, the Modified Philip Dunne (MPD) infiltrometer, was utilized to measure an important infiltration parameter (saturated hydraulic conductivity, Ksat) at multiple locations in a number of swales. The study showed that the spatial variability in the swale infiltration rate was substantial, requiring 20 or more measurements along the highway to get a good estimate of the mean swale infiltration rate. This study also developed a ditch check filtration system that can be installed in swales to provide significant treatment of dissolved heavy metals and dissolved phosphorous in stormwater runoff. The results were utilized to develop design guidelines and recommendations, including sizing and treatment criteria for optimal performance of the full-scale design of these filters. Finally, the best available knowledge on swale maintenance was combined with information obtained from new surveys conducted to develop recommendations for swale maintenance schedules and effort. The recommendations aim toward optimizing the cost-effectiveness of roadside swales and thus provide useful information to managers and practitioners of roadways. The research results and information obtained from this study can thus be used to design swale systems for use along linear roadway projects that will receive pollution prevention credits for infiltration. This will enable the utilization of drainage ditches to their full pollution prevention potential, before building other more expensive stormwater treatment practices throughout Minnesota and the United States.Minnesota Department of Transportation Research Services & LibraryAhmed, Farzana; Natarajan, Poornima; Gulliver, John S.; Weiss, Peter T.; Nieber, John L.. (2014). Assessing and Improving Pollution Prevention by Swales. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/168022
Performance Evaluation of Grassed Swales for Stormwater Pollution Control
No full textAbstractGrassed swale has become a common feature for stormwater quality control by removing pollutants and reducing peak flows. In this study, three common transmission grassed swales located at different places in China were compared during two high intensity storm events to understand variation of four different kinds of pollutants (TSS, NH4+-N, NO3--N and COD) in grassed swale and to verify the accuracy of BMPs statistical data. TSS has shown great removal rate by grassed swale with a 92% concentration reduction. The decrease of NH4+-N concentration remained stable due to the fact that the main mechanism for NH4+-N removal is the adsorption of surface soil particles and plant roots. Different from NH4+-N, NO3--N could be re-released into water and its removal rate is deeply related to seasonal pattern. In addition, COD in dissolved pattern was removed deeply and its removal rate ranged from 86.35% to 51.72%. In summary, the present study indicates that the grassed swale is an effective stormwater treatment and the design of grassed swale should be based on the local hydrological conditions and the types of pollutants of stormwater in different countries or areas
Revealing Public Perceptions of Biodiverse vs. Turf Swales: Balancing Enhanced Ecosystem Services with Heightened Concerns
No full textGreen stormwater infrastructure (GSI) is increasingly implemented worldwide to address stormwater issues while providing co-benefits such as habitat provision. However, research on public perceptions of GSI’s ecosystem benefits is limited, and barriers such as perception and maintenance hinder biodiversity promotion in GSI. Through an online survey (n = 781), we explored how residents in four Northeast US urban areas—Prince George’s County and Montgomery County, MD, New York City, and Philadelphia, PA—perceived the benefits and concerns regarding two types of bioswales (biodiverse and turf). Biodiverse swales feature various plants to promote biodiversity, whereas turf swales are primarily grass-covered. Our analyses included paired-samples t-tests, independent t-tests, one-way repeated measures ANOVA tests, and one-way ANOVA tests to compare perceptions across bioswale types, aspects of benefit/concern, and locations. Both bioswale types were recognized for enhancing green spaces and neighborhood aesthetics. Residents perceived greater environmental and social benefits from biodiverse swales than turf swales, particularly for habitat provision. While overall concerns for both bioswale types were low, potential issues like pest cultivation and the unappealing appearance of biodiverse swales remain significant barriers. Notably, implementing biodiverse swales alleviated initial concerns, especially about pests, suggesting familiarity can enhance acceptance. Location-specific differences in perception were observed, with New York City showing higher perceived benefits and concerns and Montgomery County exhibiting the lowest concerns. This variance is likely due to distinct urban environments, levels of environmental awareness, and demographic profiles
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