Assessing characteristic time and space scales of in-sewer processes by analysis of one year of continuous in-sewer monitoring data

2012 ◽  
Vol 66 (8) ◽  
pp. 1614-1620 ◽  
Author(s):  
R. P. S. Schilperoort ◽  
J. Dirksen ◽  
J. G. Langeveld ◽  
F. H. L. R. Clemens
Keyword(s):  
High Frequency ◽  
Peak Load ◽  
Storm Events ◽  
Pollutant Concentrations ◽  
Load Factors ◽  
Wet Weather ◽  
Using Data ◽  
One Year ◽  
Dry Weather Flow

Long-term and high-frequency in-sewer monitoring opens up a broad range of possibilities to study (influences on) water quantity and quality variations. Using data from the Eindhoven wastewater system in The Netherlands both dry weather flow and wet weather flow situations have been studied. For approximately 160 dry weather days mean diurnal variations of flow and pollutant concentrations have been derived. For wet weather situations (≈ 40 storm events) peak load factors have been studied. Generally, peak load factors for all considered pollutant parameters are larger than one. Peak load factors for particulate matter are larger than for dissolved constituents. Also, the smallest catchment area consistently shows the largest mean peak factors and vice versa.

Estimation of annual pollutant loadings in two small catchments and examination of their differences caused by regional properties

2006 ◽  
Vol 53 (2) ◽  
pp. 33-44 ◽  
Author(s):  
S. Fujii ◽  
M. Moriya ◽  
P. Songprasert ◽  
H. Ihara
Keyword(s):  
River Basin ◽  
High Frequency ◽  
Storm Event ◽  
Precipitation Pattern ◽  
Storm Events ◽  
Rainfall Events ◽  
Survey Results ◽  
One Year ◽  
Small Catchments

A series of runoff surveys was conducted for more than one year in two small catchments of the Kamo River basin (75.4 km2) and the Takano River basin (66.8 km2) in Kyoto, Japan, which adjoin each other, and may have the same precipitation pattern. The investigation consisted of a high-frequency periodic survey, a long-term regular survey and a storm event survey. The survey results were compared with the regional properties of the basins, and the following results were obtained. (1) Pollutant loadings were successfully estimated as two portions of base discharge and storm events discharge from the survey results. (2) Estimated annual loading of the sites was 2.9–4.5, 1.3–1.8, 17–27, 1.3–2.2, 0.076–0.97 t/km2/y, respectively for CODMn, DOC, SS, TN and TP. (3) 52–53% of the whole flow, which was caused by rainfall events, conveyed 81–87, 68–73, 92–95, 64–67, 76–81% of the whole loading, respectively for CODMn, DOC, SS, TN and TP. (4) Differences of regional properties in two basins cause different runoff patterns, but the differences in runoff patterns also depend on the rainfall patterns. In general, a more urbanized basin receives early and strong influence of precipitation on the storm event runoff.

scholarly journals Long-term behavior and stability of calibration models for NO and NO<sub>2</sub> low cost sensors

2022 ◽  
Author(s):  
Horim Kim ◽  
Michael Müller ◽  
Stephan Henne ◽  
Christoph Hüglin
Keyword(s):  
Electrochemical Sensors ◽  
Low Cost ◽  
Air Pollutant ◽  
Coefficient Of Determination ◽  
Monitoring Networks ◽  
Pollution Levels ◽  
Pollutant Concentrations ◽  
Air Quality Measurements ◽  
One Year

Abstract. Low-cost sensors are considered as exhibiting great potential to complement classical air quality measurements in existing monitoring networks. However, the use of low-cost sensors poses some challenges. In this study, the behavior and performance of electrochemical sensors for NO and NO2 were determined over a longer operating period in a real-world deployment. After careful calibration of the sensors, based on co-location with reference instruments at a rural traffic site during six months and by using robust linear regression and random forest regression, the coefficient of determination of both types of sensors were high (R2 > 0.9) and the root mean square error (RMSE) of NO and NO2 sensors were about 6.8 ppb and 3.5 ppb, respectively, for 10-minute mean concentrations. The RMSE of the NO2 sensors, however, more than doubled, when the sensors were deployed without re-calibration for a one-year period at other site types (including urban background locations), where the range and the variability of air pollutant concentrations differed from the calibration site. This indicates a significant effect of the re-location of the sensors on the quality of their data. During deployment, we found that the NO2 sensors are capable of distinguishing general pollution levels, but they proved unsuitable for accurate measurements, mainly due to significant biases. In order to investigate the long-term stability of the original calibration, the sensors were re-installed at the calibration site after deployment. Surprisingly, the coefficient of determination and the RMSE of the NO sensor remained almost unchanged after more than one year of operation. In contrast, the performance of the NO2 sensors clearly deteriorated as indicated by a higher RMSE (about 7.5 ppb, 10-minute mean concentrations) and a lower coefficient of determination (R2 = 0.59).

Subglottic haemangioma in the infant: contribution by CO2 laser

1989 ◽  
Vol 103 (10) ◽  
pp. 930-934 ◽  
Author(s):  
M. Remacle ◽  
X. Declaye ◽  
A. Mayne
Keyword(s):  
High Frequency ◽  
Considerable Improvement ◽  
Jet Ventilation ◽  
Prolonged Intubation ◽  
High Frequency Jet Ventilation ◽  
Low Intensity ◽  
One Year ◽  
Subglottic Haemangioma ◽  
Spontaneous Evolution

AbstractThe availability of the low intensity CO2 laser beam, and the possibility of defocalization that is associated with control of subglottic high frequency jet ventilation, requires a more interventionist attitude regarding dyspnoea caused by a subglottic haemangioma in the infant. It is indeed possible reliably to reduce the size of the subglottic haemangioma, and thus to avoid a lengthy period of intensive care, as well as the problems of prolonged intubation or tracheostomy for drainage, while also avoiding long term steroid therapy. This approach in no way affects the spontaneous evolution of subglottic haemangioma in the infant; there is a tendency for the haemangioma to regress after the age of one year. The treatment does, however, permit a considerable improvement in the comfort of the infant's life during this difficult period between 3 and 12 months.We illustrate this new attitude by presenting a report on four cases.

scholarly journals Development of a General Calibration Model and Long-Term Performance Evaluation of Low-Cost Sensors for Air Pollutant Gas Monitoring

2018 ◽  
Author(s):  
Carl Malings ◽  
Rebecca Tanzer ◽  
Aliaksei Hauryliuk ◽  
Sriniwasa P. N. Kumar ◽  
Naomi Zimmerman ◽  
...  
Keyword(s):  
Linear Models ◽  
Low Cost ◽  
Air Pollutant ◽  
Superior Performance ◽  
Calibration Model ◽  
Quadratic Regression ◽  
Calibration Models ◽  
Using Data ◽  
One Year

Abstract. Assessing the intra-city spatial distribution and temporal variability of air quality can be facilitated by a dense network of monitoring stations. However, the cost of implementing such a network can be prohibitive if traditional high-quality, expensive monitoring systems are used. To this end, the Real-time Affordable Multi-Pollutant (RAMP) monitor has been developed, which can measure up to five gases including the criteria pollutant gases carbon monoxide (CO), nitrogen dioxide (NO2), and ozone (O3), along with temperature and relative humidity. This study compares various algorithms to calibrate the RAMP measurements including linear and quadratic regression, clustering, neural networks, Gaussian processes, and random forests. Using data collected by more than sixty RAMP monitors over periods ranging up to eighteen months, it was found that quadratic regression models or a hybrid of random forest and linear models tend to be the most effective calibration models overall. In specific cases, other types of models can have comparable or even superior performance. Furthermore, generalized calibration models may be used instead of individual models with only a small reduction in overall performance. For long-term deployments, it is recommended that new models be developed each year, due to the noticeable change in performance when models for one year were used for processing data collected in the subsequent year. This makes annually-developed generalized calibration models even more useful since only a subset of deployed monitors are needed to build these models. These results will help guide future efforts in the calibration and use of low-cost sensor systems worldwide.

scholarly journals LONGSHORE TRANSPORT AND SEDIMENTATION IN A NAVIGATION CHANNEL AT BLANKENBERGE (BELGIUM)

2012 ◽  
Vol 1 (33) ◽  
pp. 111 ◽  
Author(s):  
Nicolas Zimmermann ◽  
Koen Trouw ◽  
Li Wang ◽  
Mieke Mathys ◽  
Rosalia Delgado ◽  
...  
Keyword(s):  
Wave Climate ◽  
Storm Events ◽  
Climate History ◽  
Longshore Transport ◽  
Navigation Channel ◽  
Morphological Modelling ◽  
One Year ◽  
Modelling Methods ◽  
Total Sediment

The harbour of Blankenberge in Belgium experiences strong sedimentation in its entrance channel requiring frequent dredging. In order to investigate under which conditions this sedimentation is the most pronounced, the instationary coastal model XBeach is used. This paper presents results of long-term morphology modelling of channel sedimentation after applying a specific methodology for input reduction. A reduced time series representative of the annual wind-wave climate is run in combination with a representative tide and a constant morphological acceleration factor (morfac) to cover one year of erosion-sedimentation. While this approach does come with side effects, it has the important advantage to be easy to implement and to preserve part of the climate history compared to other approaches such as MorMerge and a time-varying morfac approach (described in the paper). With this approach and default settings, XBeach is shown to reproduce both qualitatively and quantitatively well the measured sedimentation. Results show that tide, wind and waves all contribute significantly to the total sediment transport, and that both continuous transport and individual storm events cause strong sedimentation. Some aspects of morphological modelling methodologies are discussed, relative to the calibration, input reduction and long-term modelling methods.

Long-Term Performance of Buybacks in India

2018 ◽  
Vol 19 (6) ◽  
pp. 1554-1566 ◽  
Author(s):  
Jayanta Kumar Seal ◽  
Jasbir Singh Matharu
Keyword(s):  
Event Study ◽  
Stock Exchange ◽  
Study Methodology ◽  
Using Data ◽  
One Year ◽  
Long Term Performance ◽  
Term Performance ◽  
Event Study Methodology

This study tries to find out the post-announcement performance of the buyback firms over the long term in India using data from the Bombay Stock Exchange (BSE). We have chosen the event study methodology and compared the performance for a one-year, a three-year, and a five-year period. The benchmarks chosen are the Sensex, the BSE 500, the size matched firms and the size and industry matched firms. The findings of the study show overperformance by buyback firms when compared to the Sensex and the BSE 500 but no conclusion can be drawn when compared to the size matched firms and size and industry matched firms.

Runoff characteristics of highway pollutants based on a long-term survey through a year

2008 ◽  
Vol 57 (11) ◽  
pp. 1769-1776 ◽  
Author(s):  
A. Ichiki ◽  
F. Ido ◽  
T. Minami
Keyword(s):  
Aromatic Hydrocarbons ◽  
Basic Unit ◽  
Water Sampling ◽  
Storm Events ◽  
Chemical Substances ◽  
Polycyclic Aromatic ◽  
One Year ◽  
Pollutant Runoff ◽  
Long Term Survey

Highway pollutants generated mainly from traffics are repeating accumulation, raise, drift and move on the highways. Some of them are removed by road cleanings done regularly, the others are flushed by stormwater into receiving water. The objectives of this study are to survey characteristics of the highway pollutants, and to quantify their behavior on the highways. The study area is a part of Meishin Expressway running through the main island of Japan. Surveys on pollutant runoff from the highway were done for all storm events through one year from December 2004 to November 2005. For the surveys, samples were collected by continuous water sampling during storm events. And chemical substances in each sample such as SS, TOC, TN, TP, heavy metals and polycyclic aromatic hydrocarbons (PAHs) for each class of particle size were measured. Using the results of the survey, characteristics of pollutant runoff during storm events were examined. And it cleared the basic unit loads for the highway pollutants throughout a year. As a result, some significant knowledge for the environmental management of highway pollution has been obtained.

scholarly journals How many measurements are needed to estimate accurate daily and annual soil respiration fluxes? Analysis using data from a temperate rainforest

2016 ◽  
Author(s):  
Jorge F. Perez-Quezada ◽  
Carla E. Brito ◽  
Julián Cabezas ◽  
Mauricio Galleguillos ◽  
Juan P. Fuentes ◽  
...  
Keyword(s):  
High Frequency ◽  
Data Series ◽  
Sampling Strategies ◽  
Full Data ◽  
Temperate Rainforest ◽  
Partial Data ◽  
Frequency Sampling ◽  
Using Data ◽  
One Year ◽  
High Frequency Sampling

Abstract. Making accurate estimations of daily and annual Rs fluxes is key for understanding the carbon cycle process and projecting effects of climate change. In this study we used high-frequency sampling (24-measurements per day) of Rs in a temperate rainforest during one year, with the objective of answering the questions of when and how often measurements should be made to obtain accurate estimations of daily and annual Rs. In this aim, we randomly selected data to simulate samplings of 1, 2, 4 or 6 measurements per day (distributed either during the whole day or only during daytime) combined with 4, 6, 12, 26 or 52 measurements per year. Based on the comparison of partial-data series with the full-data series, we estimated the performance of different partial sampling strategies based on bias, precision and accuracy. In the case of annual Rs estimation, we compared the performance of interpolation vs. using non-linear modelling based on soil temperature. The results show that, under our study conditions, sampling twice a day was enough to accurately estimate daily Rs (RMSE 

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