The purpose of this paper is to present a simple yet highly effective method to reconstruct missing data in flow time series. The presence of missing values in network flow data severely restricts their use for an adequate management of billing systems and for network operation. Despite significant technology improvements, missing values are frequent due to metering, data acquisition and storage issues. The proposed method is based on a weighted function for forecast and backcast obtained from existing time series models that accommodate multiple seasonality. A comprehensive set of tests were run to demonstrate the effectiveness of this new method and results indicated that a model for flow data reconstruction should incorporate daily and seasonal components for more accurate predictions, the window size used for forecast and backcast should range between 1 and 4 weeks, and the use of two disjoint training sets to generate flow predictions is more robust to detect anomalous events than other existing methods. Results obtained for flow data reconstruction provide evidence of the effectiveness of the proposed approach.
A wave of privatization is rolling through the water industry – at the environment‘s expense? In order to provide an answer to this question, the Environmental-Rating agency oekom research AG, Munich, put a number of water supply companies and manufacturers of water appliances to the environmental test. In results published today, oekom identifies the British water supplier Severn Trent as the environmental leader of the water supply group with a B grade in the overall Environmental-Rating. The Austrian water...
Aqwest-Bunbury Water Board has introduced a range of cleaner production measures designed to improve the overall efficiency of its water treatment plants.
Background
Aqwest, the operating arm of the Bunbury Water Board, supplies water to approximately 12,000 service connections for the 30,000 residents of the town of Bunbury, Western Australia, 180km south of Perth.
Aqwest operates seven water treatment plants, associated bores and high level booster pumps. Its main activities are water treatment and water...
Deutsche Telekom and NTT Stand Out in the First Environmental Check of the Telecommunications Industry
Deutsche Telekom AG and Nippon Telegraph & Telephone (NTT) are both first in an independent Environmental-Rating of 16 telecommunication companies from eleven countries carried out by the Munich-based rating agency ökom. Both companies received the grade C+ and therefore stood out against the industry average of D+. Telekom Italia Mobile and the Dutch Royal KPN were the tail-lights, both receiving a D-. The...
When determining the consequences of accidental release flow rates from pressurized gas systems, it is important to select the appropriate type of air pollution dispersion model. For released gases which are lighter than or equal to the ambient air density, Gaussian dispersion models as described in Beychok`s text1 should be used. For released gases which are heavier than air, a dense gas model such as SLAB2 or DEGADIS3 should be used.
It is also important to determine realistic flow rates for accidental release...
` In order to determine the impacts of a particular discharge on ambient water quality, it is usually necessary to model the diffusion and dispersion of the discharge in the relevant water body. The approach applies both to new discharges and to upgrading of existing sources. This note provides guidance on models that may be applicable in the context of typical Bank projects.`
Introduction
Mathematical models can be used to predict changes in ambient water quality due to changes in discharges of wastewater. In...
It is common for ground water to be contaminated with the water soluble substances found in overlying soils. Many of the required data elements are similar, e.g., pH, TOC, BOD, COD, oil and grease, contaminant identification and quantification, and soil and aquifer characterization. Additional water quality monitoring data elements include hardness, ammonia, total dissolved solids, and metals content (e.g., iron, manganese). Knowledge of the site conditions and history may contribute to selecting a list of...
Introduction
Surface and subsurface soils have different characteristics in natural attenuation. Mobile contaminants in subsurface soils diffuse into soil vapor and aqueous phase and thus are relatively easily subject to natural subsurface processes that can attenuate these contaminants. Most high-molecular-weight (persistent) organic and many inorganic contaminants will be immobilized in the subsurface soil matrix. These persistent organic contaminants often are difficult to degrade and the inorganic metals are...
Introduction
Fracturing is an enhancement technology designed to increase the efficiency of other in situ technologies in difficult soil conditions. The fracturing extends and enlarges existing fissures and introduces new fractures, primarily in the horizontal direction. When fracturing has been completed, the formation is then subjected to vapor extraction, either by applying a vacuum to all wells or by extracting from selected wells, while other wells are capped or used for passive air inlet or forced air...
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