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In the chemical industry, real‐time flooding prognosis is a necessity for packed‐column operation because the flooding phenomenon interferes with the performance of production systems. In this work, the profile monitoring technique is utilized to capture the dynamic behavior of pressure drop, which is an important indicator for the flooding phenomenon. In each moving window, the pressure drop signals are described by using an exponential generalized autoregressive conditional heteroskedastic model. The onset of the flooding phenomenon is then indicated by changes in model parameters. Moreover, to efficiently capture the process change, a nonparametric approach is utilized to establish a statistical control chart. Experimental and comparison results show the advantages of the proposed method. 相似文献
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Amy M. Kahler Theresa L. Cromeans Jacquelin M. RobertsVincent R. Hill 《Water research》2011,45(4):1745-1751
There is a need for more information regarding monochloramine disinfection efficacy for viruses in water. In this study, monochloramine disinfection efficacy was investigated for coxsackievirus B5 (CVB5), echovirus 11 (E11), murine norovirus (MNV), and human adenovirus 2 (HAdV2) in one untreated ground water and two partially treated surface waters. Duplicate disinfection experiments were completed at pH 7 and 8 in source water at concentrations of 1 and 3 mg/L monochloramine at 5 and 15 °C. The Efficiency Factor Hom (EFH) model was used to calculate CT values (mg-min/L) required to achieve 2-, 3-, and 4-log10 reductions in viral titers. In all water types, monochloramine disinfection was most effective for MNV, with 3-log10 CT values at 5 °C ranging from 27 to 110. Monochloramine disinfection was least effective for HAdV2 and E11, depending on water type, with 3-log10 CT values at 5 °C ranging from 1200 to 3300 and 810 to 2300, respectively. Overall, disinfection proceeded faster at 15 °C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but there was no indication that overall disinfection efficacy was enhanced or inhibited in any one water type. CT values for HAdV2 in two types of source water exceeded federal CT value recommendations in the US. The results of this study demonstrate that water quality impacts the inactivation of viruses and should be considered when developing chloramination plans. 相似文献
5.
Neal C House WA Jarvie HP Neal M Hill L Wickham H 《The Science of the total environment》2005,344(1-3):107-128
Variations in phosphorus (P) concentrations in an agriculturally impacted river draining a Chalk aquifer and an associated canal in the west of the Thames Basin, southern England are examined and linked to agricultural and sewage sources and within river/canal process controls. The study area comprises the River Dun, the adjacent River Kennet and the Kennet and Avon (K&A) Canal. Large seasonal variations are observed for soluble reactive phosphorus (SRP) and dissolved silicon (Si) with low concentrations in the spring and summer times when biological activity is high. The K&A Canal shows the largest SRP and Si concentration declines. This reflects high biological activity coupled with higher temperatures and higher water residence times. The extent of SRP removal is examined in relation to organic (uptake/release with phytoplankton growth/decay) and, to a lesser extent, inorganic (SRP coprecipitation with calcite) mechanisms. Boron (B) is used as a tracer of sewage sources. Agricultural inputs of both dissolved and particulate P (PP) can be important particularly under conditions where the catchment is wet and near surface/overland flow is important: sewage treatment works effluent and septic tank discharges to groundwater also probably provide a major component of the SRP occurring within the water column. The canal, and to a lesser extent the river, acts as sink for P in sewage effluent sources due to the high biological activity especially during the spring and summer. The aquifer probably acts as a major sink for agricultural and septic tank inputs of P. 相似文献
6.
Multiple lines of evidence to identify the sources of fecal pollution at a freshwater beach in Hamilton Harbour, Lake Ontario 总被引:2,自引:0,他引:2
Multiple microbial source-tracking methods were investigated to determine the source of elevated Escherichia coli levels at Bayfront Park Beach in Hamilton Harbour, Lake Ontario. E. coli concentrations were highest in wet foreshore sand (114,000 CFU/g dry sand) and ankle-depth water (177,000 CFU/100mL), declining rapidly in deeper waters. Many gull and geese droppings were enumerated each week on the foreshore sand within 2m of the waterline. Both antimicrobial resistance analysis and rep-PCR DNA fingerprinting of E. coli collected at the beach and nearby fecal pollution sources indicated that E. coli in sand and water samples were predominantly from bird droppings rather than from pet droppings or municipal wastewater. Both methods indicated a trend of decreasing bird contamination, and increasing wastewater contamination, moving offshore from the beach. When foreshore sand was treated as a reservoir and secondary source of E. coli, waterborne E. coli were found to be more similar to sand isolates than bird or wastewater isolates out to 150 m offshore. Multiple lines of evidence indicated the importance of bird droppings and foreshore sand as primary and secondary sources of E. coli contamination in beach water at Bayfront Park. 相似文献
7.
This study describes a process for water treatment by continuous adsorption and electrochemical regeneration using an air-lift reactor. The process is based on the adsorption of dissolved organic pollutants onto an adsorbent material (a graphite intercalation compound, Nyex®1000) and subsequent electrochemical regeneration of the adsorbent leading to oxidation of the adsorbed pollutant. Batch experiments were carried out to determine the adsorption kinetics and equilibrium isotherm for adsorption of a sample contaminant, the organic dye Acid Violet 17. The adsorbent circulation rate, the residence time distribution (RTD) of the reactor, and treatment by continuous adsorption and electrochemical regeneration were studied to investigate the process performance. The RTD behaviour could be approximated as a continuously stirred tank. It was found that greater than 98% removal could be achieved for continuous treatment by adsorption and electrochemical regeneration for feed concentrations of up to 300 mg L−1. A steady state model has been developed for the process performance, assuming full regeneration of the adsorbent in the electrochemical cell. Experimental data and modelled predictions (using parameters for the adsorbent circulation rate, adsorption kinetics and isotherm obtained experimentally) of the dye removal achieved were found to be in good agreement. 相似文献
8.
The water quality of the River Thame, a tributary of the River Thames in the Thames basin, is described in relation to point and diffuse contaminant inputs and runoff from permeable and impermeable bedrock geology with their own characteristic water quality. The data is examined to see if the market town of Aylesbury in the upper part of the catchment influences water quality. Previous studies highlighted the influence of Aylesbury sewage treatment works (STW) on soluble reactive phosphorus (SRP) concentrations in the river before and after phosphorus (P) stripping at the STW. Variations in water quality along the river are described and the study indicates that, apart from SRP, water quality determinants seem to be relatively unaffected by Aylesbury. The Thame water quality is compared with other catchment typologies and it is very similar to that of the main stem of the Thames even though the Thames is mainly Chalk groundwater fed. Differences in water quality largely link to the amount of STW effluent within the rivers and to the endmember compositions of the groundwater and near surface water sources. 相似文献
9.
Glen Hill 《Architectural Theory Review》2013,18(2):72-88
Earlier this year I was asked to give a talk about historical research to a research methods class being held for graduate research students in their probationary year. This paper is an outcome of that presentation. The paper attempts to illustrate the polarities evident in contemporary historiography and, where possible, to draw out their implications for architectural history research. Because of its pedagogical context, the contours of the debate are deliberately accentuated and the resolution (within a Heideggerian framework) overtly formulaic. Despite this lack of subtlety (or perhaps because of it?) the approach appeared to work effectively in fostering student engagement with the current debate. ...I understand the postmodern predicament to imply no-thingness. No-thing out there to substantiate. No ‘there, there’ to represent. Therefore postmodern history implies no story, no narrative, no interpretation and no explanation.1 相似文献
10.
David R. Hill 《Journal of the American Planning Association. American Planning Association》2013,79(3):302-314
Over the last quarter-century Jane Jacobs has developed the argument that the dense central areas of large cities are both quality living environments and the indispensable hatchery of new jobs and economic advances for society as a whole. Her most recent book, Cities and the Wealth of the Nations, extends her earlier urban design and economic thought to the regional, national, and international scales, and it completes the sketch of a general theory of planning. Despite her great popularity, her many formulations have not been summarized for professional planning audiences, located in the context of other planning ideas, or assessed for theoretical quality. This article addresses each of those topics. I find her theoretical strengths to be originality, emotional force, style, and timeliness. I give her mixed reviews for completeness, consistency, equity, technical design, and impact. Her weakest areas are in strategic detail, empirical verifiability, and documentation. 相似文献