Leakage Estimation Research Articles

The Evolution of Leakage and Retirement Asset Flows in the U.S.

This paper generates new, aggregate estimates of retirement savings flows in the U.S. from 2003 to 2015, and provides detailed estimates of leakage from tax-preferred retirement savings accounts to pre-retirement age individuals. We create a nationally-representative panel of individuals using a sample of administrative tax data with over 140 million person-year observations. These data contain information on retirement contributions, distributions, and transfers between accounts. We estimate that between 2003 and 2015 distributions from defined contribution plans and IRAs to individuals age 50 or younger were equal to 22 percent of the contributions made by this age group. When estimating the correlation between common life events and the probability of leakage, we find that job separations correspond with an increase in the probability of leakage of over 200 percent. Job separations generating the receipt of unemployment insurance (UI) -- a proxy for an involuntary job separation -- are associated with higher leakage than non-UI separations. Other types of events, such as income shocks, home purchases, and the onset of tuition payments are also associated with leakage.

Impact of Pressure-Driven Demand on Background Leakage Estimation in Water Supply Networks

Increasing water demand due to urbanization creates a need to develop schemes for managing water supply networks (WSNs). In recent years, hydraulic modeling of WSNs has been used to assess the state of networks in terms of leakage analysis and pressure control. These models are based on demand-driven modeling (DDM) analysis and pressure-driven modeling (PDM) analysis. The former assumes that the nodal demand is fulfilled consistently regardless of the nodal pressure head. The latter appraises the demand as a function of the available pressure head at the nodes. In a previous paper by Adedeji et al. (2017), an algorithm was presented for background leakage detection and estimation in WSNs. The results demonstrated that the algorithm allows the detection of critical pipes and the indication of the nodes where such critical pipes are located for possible pressure control. However, such an algorithm assumes a demand-driven condition of WSNs. In this paper, a pressure-driven modeling is integrated into the developed algorithm with emphasis on its impact on the background leakage estimate. The results obtained are compared to the demand-driven analysis using two WSNs as case studies. The results presented, which consider pipe and node levels, demonstrate that the reliance of the nodal demand on the available pressure head at the node influences the magnitude of the background leakage flow. It is conceived that this investigation might be crucial for the background leakage estimation while considering WSNs operating under pressure-deficient conditions. In this paper, the solution time for both simulation scenarios is also presented.

EnKF-based estimation of natural gas release and dispersion in an underground tunnel

With the rapid industrialization and urbanization in China, underground tunnels, as an effective way to construct and maintain energy supplies, have been widely utilized to transport natural gas in urban chemical plants and industrial parks. Natural gas transport in an underground tunnel really facilitates the repair and maintenance of gas pipelines, but could pose a high risk of causing fire or explosion in case of natural gas pipeline leakage. The reasonable estimation of natural gas leakage and subsequent spatiotemporal distribution of natural gas dispersion is of great importance for effective emergency response and loss prevention. In this study, a numerical gas transport model in conjunction with the ensemble Kalman filter (EnKF) was proposed to realize the inversion of natural gas leakage rate and predict gas dispersion in a ventilated underground tunnel. The EnKF-based model can improve gas release estimation and dispersion prediction by assimilating observation data into simulation results. The proposed model-data assimilation system was firstly validated by twin experiment, and furthermore the sensitivity of the initial-guess release rate was analyzed to verify the practicability of the proposed model. Moreover, the reasonable estimation of dynamic natural gas release rate was realized and strategic decisions on methane sensors arrangement in tunnel were provided. The reasonable results indicate that the proposed EnKF-based model is an effective method for estimating natural gas release rate and predicting real-time natural gas spatiotemporal distribution in case of natural gas release accident in an urban underground tunnel.

Evaluation of Earth Dam Leakage Considering the Uncertainty in Soil ‎Hydraulic Parameters

Analysis of earth dams is generally conducted in three stages of stability, deformability and water penetration analysis. Lack of sufficient attention to leakage, as one of the most important issues, leads to erosion and destruction of slope stability. The aim of current paper is to analyze the earth dam leakage with respect to the existing uncertainty in soil hydraulic parameters. In this research, the Monte Carlo (MC) method was used to calculate soil hydraulic parameters. Using these parameters, analysis of Alborz earth dam leakage by means of SEEP/W model based on the finite elements method was investigated. Due to the hydraulic conditions of the core soil, the total head value, pore water pressure, and water flux in core region will change. The results indicate that uncertainty in the hydraulic parameters of Alborz earth dam are significant, thus risk is important in this dam. The application of the proposed methodology in estimation of leakage from Alborz earth dam in Mazandaran province reveals its efficiency and proper accuracy in predicting the amount of leakage flow in earth dams with respect to the possible changes in the hydraulic parameters of the soil. Moreover, it was found that the quantity of seepage increases considerably when the dam is without core, therefore, the core is very necessary to decrease the value of seepage through the earth dam.

Perkiraan Tegangan Lewat Denyar Isolator Tegangan Menengah 20 kV Keramik dan Resin Epoksi berdasarkan Data Arus Bocor

This paper explains the research results of leakage current data and estimation of flashover voltage on ceramics and epoxy resin as 20 kV outdoor insulator in a chamber with tropical climate conditions. The waveform of leakage current (LC) was measured using a digital oscilloscope. The digital data was transferred to a personal computer using a RS-232 cable. The digital data was analyzed using Fast Fourier Transform. The result showed that LC was affected by various environment conditions like temperature, humidity and pollution. LC of ceramics insulator was higher than epoxy resin insulator in low temperature, high humidity and high pollution condition.

The effects of the Kyoto Protocol on the carbon trade balance

This study presents estimates of the magnitude of carbon leakage as a consequence of emission reduction commitments under the Kyoto Protocol using gravity model-style regression analysis on data from the WIOD project. The carbon trade balance between 2002 and 2009 was reduced by 705 megatons of carbon dioxide due to Kyoto and carbon leakage amounts to slightly above 4% of traded carbon dioxide emissions. We highlight four previously neglected issues: First, we control for multilateral trade resistance in the estimation of a unilateral policy by using a two-stage procedure. Second, we control explicitly for the effect of Eastern European countries on leakage estimates. We show that this country group strongly affects the baseline estimates in the framework introduced by Aichele and Felbermayr (Rev Econ Stat 97(1):104–115, 2015). Third, we introduce an alternative specification of the Kyoto variable. Fourth, this is the first study to present econometric evidence for the magnitude of carbon leakage from services sectors. While service elasticities are estimated to be sizable, strong leakage is limited to transport sectors as well as renting of machinery. The manufacturing sectors of metals, machinery and transport equipment are responsible for three quarters of observed leakage.

VVER 1000 Severe Accident Analyses Using MELCOR Code

This work describes the computer model development of the water–water energetic reactor (VVER) 1000 nuclear power plant (NPP) in the methods for estimation of leakages and consequences of releases (MELCOR) 1.8.6 code and its subsequent use for the accident scenarios analysis leading to the core melting. The baseline accident scenario was a stress test case—the station blackout (SBO, the complete loss of alternating current electric power in a nuclear power plant). In addition to this, four other scenarios were analyzed in which the SBO was combined with other technological failures—the loss of steam generator feedwater system and small, medium, and large break coolant accidents (LOCA). The results provided detailed information on the time course of accident scenarios, their temperature and pressure parameters, hydrogen production, and the mass inventory released from the molten corium and debris into the containment of the NPP.

Estimates of CO2 leakage along abandoned wells constrained by new data

The viability of carbon capture and geological storage (CCS) projects depends in part on the risk that injected CO2 or displaced pore fluid will leak out of the target formation into surrounding formations or to the surface. Abandoned oil and gas wells, of which millions exist both throughout the United States and globally, form a potential conduit for this leakage. Recently, specific field measurements have been made to quantify the range of effective permeabilities that can be expected in abandoned wells, enabling us to, for the first time, combine field-scale numerical simulations of CO2 sequestration in deep saline aquifers with real data on effective permeabilities of leaky wells. Using a previously developed semi-analytical reservoir simulator that can accommodate an arbitrary sequence of alternating aquifers and aquicludes, as well as an arbitrary number of leaky wells, we investigated how the amount of CO2 that leaks out of the target formation depends on the spatial density of nearby abandoned wells and their effective permeability. Furthermore, we assess the influence that variations in pressure and temperature found between geological targets have on this dependency. We find that the observed differences in leakage between geological targets are controlled almost exclusively by differences in density of CO2 at the local subsurface conditions, causing the CO2 plume to contact a different number of wells when injecting at the same constant mass rate. We quantitatively assess the results obtained from our numerical experiments by combining them with the permeability data that have recently become available, typical spatial densities of abandoned wells, and performance requirements put forward in the literature. Our results indicate that leakage of CO2 through abandoned wells is unlikely to be a major limitation in storage security of CCS projects.

Evaluation of a Magnetic Dipole Model in a DC Magnetic Flux Leakage System

One of the most common methods for performing non-destructive testing in steel tank floors is DC magnetic flux leakage (MFL). The magnetic dipole method is the most widely used mathematical technique to predict the MFL from defects in such structures. However, due to the complexity of an exact analytical description of an MFL system, researchers often make coarse approximations for the profile of the magnetic surface charge density $\sigma _{m}$ , orientation of the magnetic field H, and variation of relative permeability $\mu _{r}$ . In this paper, the validity of these approximations is evaluated for 2-D rectangular defects in a steel plate, by comparing model predications with finite element results. The primary sources of deviation between the approximate solutions and true MFL profiles were found to be caused by assumptions that 1) $\sigma _{m}$ on the specimen surface adjacent to a flaw is zero. This assumption is equivalent to treating the orientation of H to be parallel to the specimen surface, even at locations in close proximity to a flaw and 2) local variation in permeability around the defect can be ignored. This approximation was found to cause an underestimation of $\sigma _{m}$ and, consequently, the predicted MFL. In contrast, approximating $\sigma _{m}$ to be zero at the bottom of a flaw, and approximating uniform distribution for $\sigma _{\mathbf {m}}$ on the vertical defect sides of a slot defect was found to generate only minor errors in an estimate of flux leakage.

Applications of Thermal Visual Measurements in Light of Toughened Up Legislation

The purpose of research was to verify the impact of thermal modernization of existing buildings on their energy performance in light of toughened up legislation. The paper answers the question - how thermo-modernization can affect the reduction of its needs for the building and contribute to the reduction of dust emitted, when heating is based on solid fuels. Some houses of similar typical construction which was very popular in Poland in 70’, were tested. In one of them, doors and windows were replaced, but its elevation was left without insulation, while in another one, the thermal insulation was made, but old wooden door and window framing has been left. The research carried out with the thermovision camera allows a qualitative estimation of heat leakage from buildings. The test results were developed in detail in the Flir Tools software and the value of the building’s heat demand was estimated before and after the thermomodernization of the building or replacement of framing. On the basis of the conducted research, it is justified that even very high quality framing not accompanied by the insulation of the building, is definitely insufficient to meet the requirements. Only a comprehensive approach to the thermo-modernization of any building can get the desired results. In article, solutions were chosen to meet the requirements of the DIRECTIVE 2010/31/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 19 May 2010 on the energy performance of buildings.

Estimation of the direct leakage of rotary air preheaters based on temperature distribution modeling

In thermal power plants, air preheaters are used to preheat the combustion air with residual thermal energy of the flue gas. The air leakage from air to flue gas has negative impact on the heat transfer efficiency of air preheaters and the unit thermal economy. This paper proposes an online applicable approach to estimate the direct leakage of the air preheater based on temperature distribution modeling. To describe the heat transfer process in the air preheater, energy balance equations are established after discretizing the air preheater into a number of heat transfer units, where the unstable heat transfer caused by the rotor rotation is considered. The temperature distribution of the air preheater is obtained through iterative calculation of these energy balance equations. By solving the optimization problems with the objective to meet the conservation laws of mass and energy, the direct leakage of the secondary air and the primary air is estimated. Pseudo-online simulations are carried out with the history data of a 300 MW subcritical unit to verify the approach. The updating period of the calculation results is set to 30 s so that the proposed approach may be applied for online monitoring purposes.

Leakage Estimation in Water Distribution Network: Effect of the Shape and Size Cracks

The definition of the relationship between the leak outflow, the total head at the leak and other relevant parameters such as pipe stiffness, leak dimension and shape has been object of extensive studies. The attention to a correct estimation of leakages, leak law, is crucial for the management of water distribution systems. Water utilities, in fact, can reduce leakage levels through the leak detection or more usually by pressure management. In the last cases, the known of the relationship between leak discharge and pressure is fundamental. In recent decades, the use of the Torricelli equation has been questioned, because some experimental results showed that it can yield unsatisfactory results, and other formulations have been suggested to model water leakages in water distribution networks. To investigate the effectiveness of the formulations suggested by different authors, an experimental campaign was carried out at the Environmental Hydraulic Laboratory of the University of Enna (Italy) for leaks of different shape and size in polyethylene pipes. The results of the laboratory experiments contribute to clarify the applicability of the leak law for circular and rectangular leaks and suggest that Torricelli formulation is valid in absence of leak area deformation. Furthermore, the analysis contributes to the knowledge of the coefficients of the leak laws used to estimate the leakage outflow.

Анализ существующих методов оценки утечек жидкости между шаровым поршнем и трубопроводом в ТПУ

Анализ существующих методов оценки утечек жидкости между шаровым поршнем и трубопроводом в ТПУ

Interannual Agulhas Leakage Variability and Its Regional Climate Imprints

We investigate the interannual variability of Agulhas leakage in an ocean-eddy-resolving coupled simulation and characterize its influence on regional climate. Many observational leakage estimates are based on the study of Agulhas rings, whereas recent model studies suggest that rings and eddies carry less than half of leakage transport. While leakage variability is dominated by eddies at seasonal time scales, the noneddy leakage transport is likely to be constrained by large-scale forcing at longer time scales. To investigate this, leakage transport is quantified using an offline Lagrangian particle tracking approach. We decompose the velocity field into eddying and large-scale fields and then recreate a number of total velocity fields by modifying the eddying component to assess the dependence of leakage variability on the eddies. We find that the resulting leakage time series show strong coherence at periods longer than 1000 days and that 50% of the variance at interannual time scales is linked to the smoothed, large-scale field. As shown previously in ocean models, we find Agulhas leakage variability to be related to a meridional shift and/or strengthening of the westerlies. High leakage periods are associated with east–west contrasting patterns of sea surface temperature, surface heat fluxes, and convective rainfall, with positive anomalies over the retroflection region and negative anomalies within the Indian Ocean to the east. High leakage periods are also related to reduced inland convective rainfall over southeastern Africa in austral summer.

Buffering distance between hazardous waste landfill and water supply wells in a shallow aquifer

The vulnerability of engineering barrier and the toxicity of leachate increase the need to maintain a certain buffering distance between landfill and drinking water sources. In order to provide decision-making support and technical guidance for the determination, and management of buffering distance, this paper coupled the dose-response model, leakage estimation model, exponential decay source model, and the advection-dispersion model for contaminants transportation and transformation in vadose and aquifer groundwater, and constructed an integral risk-based framework to help to calculate the buffering distance in shallow aquifers against the leachate contamination. Based on the framework and method, a case study is carried out. The results indicate that Zn and Ni have experience a similar dilution and attention process, but due to its smaller RDAF (required dilution and attenuation factor, equal to the ratio of initial concentration to limit concentration) value, Ni needs only a vertical separation distance (VSD) of 4 m (a 4 m vadose zone with saturated conductivity of 1 × 10-5 cm/s) without additional requirement on horizontal buffering distance. While, Zn requires an additional buffering distance of 380 m in addition to the VSD to achieve to be diluted/attenuated to a risk-acceptable level. 2,4-D has larger RDAF than Zn, but due to its difference in degradation characteristics from Zn, it also needs a smaller buffering distance (135 m) than Zn; Further studies shown that the sensitivity of the dilution and attenuation of heavy metals to distance is relatively weak, especially when the distance is greater than 800 m; organic pollutants are more sensitive to distance, even more than 800 m; for the landfill site to dispose organic pollutants, the buffering distance of 400 m is a conservative choice, while for sites to dispose heavy metal wastes, 400 m may be a risky decision and needs further calculation and demonstration.

Impact of hydraulic and storage properties on river leakage estimates: A numerical groundwater flow model case study from southern Benin

Study areaThe coastal sedimentary basin including the Zou and Ouémé rivers in Benin. Study focusRiver discharge loss is known to occur on the Zou and Ouémé rivers in southern Benin since a couple of decades ago. The reason behind this discharge reduction remained so far unclear. In this study, we focus on creating a 3D-numerical model of the system and on evaluating the sensitivity of leakage between the rivers and aquifers to various parameters. New hydrological insights for the regionResults show that leakages along the Zou river and Ouémé stream are tiny (i.e., ∼3% of the discharge losses). This implies that the observed water loss from the Zou and Ouémé rivers is not likely caused by the leakage (infiltration) along these rivers into the subsurface. The streambed conductance is found to be among the factors that impact less the computed leakages in the study area. This study has ranked the different hydraulic and storage properties in their order of importance with respect to the computation of river leakages along the concerned rivers. The determined rank of importance of the hydraulic and storage properties can guide river leakage modelling exercises in similar regions elsewhere.

CFD analysis of natural gas emission from damaged pipelines: Correlation development for leakage estimation

Natural Gas (NG) leak may occur from either an above- or an under-ground pipeline, resulting in environmental and financial consequences. Although there are some relations for estimating the gas leak from an above-ground pipeline, there is no equation for the calculation of a buried pipeline leakage. The main objective of this work is to develop precise gas leak calculator equations for low- and medium-pressure buried pipelines. For this, an under-ground gas pipeline is numerically modeled considering the surrounding soil as a porous medium. Two- and three-dimensional models are used to investigate the gas leak through a hole intentionally made on the pipe. Pure methane, with a steady state, compressible and turbulent flow, is assumed through the pipe. The developed correlations are functions of the pipe diameter, the hole diameter, and the gas flow pressure. Comparison of the results with previous works in the field demonstrates that considering a one-dimensional model for the pipe and neglecting the length of the pipe after the hole causes up to 20% error. The results indicate that a two-dimensional model is not precise enough for estimating the gas leak from an under-ground pipeline (due to the soil resistance in three directions in a real situation). In addition, linear, second order and fourth order relations are observed between the amount of gas leak and the three effective parameters of the pipe entry pressure, the hole diameter, and the ratio of the hole diameter to the pipe diameter, respectively. Analysis of the results indicates that the relative difference between the results of the simulation and the results given by the developed correlations is within the range of ±7% for all cases.

Antibacterial evaluation of silver nanoparticles synthesized from lychee peel: individual versus antibiotic conjugated effects.

This paper describes the extracellular synthesis of silver nanoparticles from waste part of lychee fruit (peel) and their conjugation with selected antibiotics (amoxicillin, cefixim, and streptomycin). FTIR studies revealed the reduction of metallic silver and stabilization of silver nanoparticles and their conjugates due to the presence of CO (carboxyl), OH (hydroxyl) and CH (alkanes) groups. The size of conjugated nanoparticles varied ranging from 3 to 10nm as shown by XRD. TEM image revealed the spherical shape of biosynthesized silver nanoparticles. Conjugates of amoxicillin and cefixim showed highest antibacterial activity (147.43 and 107.95%, respectively) against Gram-negative bacteria i.e. Alcaligenes faecalis in comparison with their control counterparts. The highest reduction in MIC was noted against Gram-positive strains i.e. Enterococcus faecium (75%) and Microbacterium oxydans (75%) for amoxicillin conjugates. Anova two factor followed by two-tailed t test showed non-significant results both in case of cell leakage and protein estimation between nanoparticles and conjugates of amoxicillin, cefixime and streptomycin. In case of MDA release, non-significant difference among the test samples against the selected strains. Our study found green-synthesized silver nanoparticles as effective antibacterial bullet against both Gram positive and Gram negative bacteria, but they showed a more promising effect on conjugation with selected antibiotics against Gram negative type.

Aerial Interyear Comparison and Quantification of Methane Emissions Persistence in the Bakken Formation of North Dakota, USA.

We performed an infrared optical gas imaging (OGI) survey by helicopter of hydrocarbon emissions in the Bakken formation of North Dakota. One year after an earlier survey of 682 well pads in September of 2014, the same helicopter crew resurveyed 353 well pads in 2015 to examine the persistence of emissions. Twenty-one newly producing well pads were added in the same sampling blocks. An instrumented aircraft was also used to quantify emissions from 33 plumes identified by aerial OGI. Well pads emitting methane and ethane in 2014 were far more likely to be emitting in 2015 than would be expected by chance; Monte Carlo simulations suggest >5σ deviation ( p < 0.0001) from random assignment of detectable emissions between survey years. Scaled up using basin-wide leakage estimates, the emissions quantified by aircraft are sufficient to explain previously observed basin-wide emissions of methane and ethane.

An Arcak-type state estimation design for time-delayed static neural networks with leakage term based on unified criteria

The issue of unified dissipativity-based Arcak-type state estimator design for delayed static neural networks (SNNs) with leakage term and noise distraction was considered here. An Arcak-type state observer, which is compact than the usually used Luenberger-type state estimator, is selected to implement the subject of a unified dissipativity performance of SNNs. This paper primarily concentrates on the issue of Arcak-type state estimator of delayed SNNs involving leakage delay. The first attempt is made to tackle the Arcak-type state estimator of SNNs with time delay in leakage term in this paper based on the unified criteria, by constructing a novel Lyapunov functional together with newly improved integral inequalities. As a result, a novel unified state estimation criterion is launched in the form of linear matrix inequalities (LMIs) and put forward to justify the dynamics of error system is extended dissipative with the influence of leakage term and estimator gain matrices K¯1 and K¯2. Finally, an interesting simulation study is ultimately explored to show the performance of the established unified dissipativity-based theoretical results, in which, comparison results are also made together with recent works as a special case.