scholarly journals Simulating pollutant transport over complex terrain: the hydrological component

2012 ◽  
Vol 10 (4) ◽  
pp. 1223-1235 ◽  
Author(s):  
Constantina Mita ◽  
Nicolaos Catsaros
Keyword(s):  
Channel Flow ◽  
Accurate Determination ◽  
Ground Surface ◽  
Pollutant Transport ◽  
Surface Flow ◽  
Valuable Insight ◽  
Distributed Hydrological Model ◽  
Channel Network ◽  
The Impact

AbstractThe accurate determination of surface water flow pathways is of primary importance when assessing the impact of pollutant transport and watershed physical characteristics on overland and channel water quality. The mathematical description of hydrological processes over natural watersheds, requires a detailed representation of the topography, on which the accurate determination of overland and channel flow trajectories often poses difficulties. The hydrological component of the DELTA code aims to provide valuable insight into this direction by using the semi-irregular triangulated (semi-TIN) topography model DELTA/HYDRO for establishing surface flow paths that can represent reliably the natural characteristics of a watershed, addressing several major physical hydrodynamic processes. The validity of the generated paths is tested via the integration of a conventional distributed hydrological model by routing excess rainfall over ground surface and through a channel network to the watershed outlet, for a series of storm episodes on a small, but relatively complex watershed. The encouraging results obtained demonstrate the promising application potential of the model, which can be additionally complemented with a pollutant transport component to address the interactions of soluble chemicals between soil surface and overland/channel flow, in the context of a fully integrated model.

scholarly journals Sulfur dioxide layer height retrieval from Sentinel-5 Precursor/TROPOMI using FP_ILM

2019 ◽  
Vol 12 (10) ◽  
pp. 5503-5517 ◽  
Author(s):  
Pascal Hedelt ◽  
Dmitry S. Efremenko ◽  
Diego G. Loyola ◽  
Robert Spurr ◽  
Lieven Clarisse
Keyword(s):  
Sulfur Dioxide ◽  
Accurate Determination ◽  
Volcanic Eruptions ◽  
Critical Parameters ◽  
Layer Height ◽  
Learning Machine ◽  
The Impact ◽  
First Time ◽  
Better Than

Abstract. The accurate determination of the location, height, and loading of sulfur dioxide (SO2) plumes emitted by volcanic eruptions is essential for aviation safety. The SO2 layer height is also one of the most critical parameters with respect to determining the impact on the climate. Retrievals of SO2 plume height have been carried out using satellite UV backscatter measurements, but, until now, such algorithms are very time-consuming. We have developed an extremely fast yet accurate SO2 layer height retrieval using the Full-Physics Inverse Learning Machine (FP_ILM) algorithm. This is the first time the algorithm has been applied to measurements from the TROPOMI instrument onboard the Sentinel-5 Precursor platform. In this paper, we demonstrate the ability of the FP_ILM algorithm to retrieve SO2 plume layer heights in near-real-time applications with an accuracy of better than 2 km for SO2 total columns larger than 20 DU. We present SO2 layer height results for the volcanic eruptions of Sinabung in February 2018, Sierra Negra in June 2018, and Raikoke in June 2019, observed by TROPOMI.

Determining FAC Degradation From NDE Data

2009 ◽  
Author(s):  
Harold M. Crockett ◽  
Jeffrey S. Horowitz
Keyword(s):  
Error Propagation ◽  
Power Plants ◽  
Degradation Mechanism ◽  
Accurate Determination ◽  
Wear Rates ◽  
Flow Acceleration ◽  
Inspection Data ◽  
Evaluation Approaches ◽  
The Impact

Flow-acceleration corrosion (FAC) is a degradation mechanism that impacts carbon steel piping components and equipment under conditions often found in both nuclear and fossil power plants. To deal with this type of degradation, many utilities have instituted inspection programs designed to discover dangerous situations well before failures occur. Inspections to determine FAC damage are normally done using the Ultrasonic Technique (UT) although other methods are also used. For large bore components, the most commonly used inspection approach is gridded UT measurements. Experience has shown that the amount of degradation that typically occurs between inspections is comparable to the uncertainty of the UT measurements. Thus, the accurate determination of the actual wear rates is difficult as the measurement uncertainties tend to cause over-stating the actual degradation. To deal with this problem, EPRI has developed a number of evaluation approaches for interpreting data from one inspection, from two sets of inspections and from more than two sets of inspections. The application of these methods to inspection data will be discussed demonstrating the performance of the different approaches. The impact of the error propagation on the accuracy of these methods and recommendations for different circumstances will be presented.

Improving quality of care and reducing costs with angiogenesis-specific imaging tests in metastatic breast cancer.

2012 ◽  
Vol 30 (34_suppl) ◽  
pp. 150-150
Author(s):  
Carolyn Bodnar ◽  
L. Clark Paramore ◽  
Kevin B. Knopf
Keyword(s):  
Breast Cancer ◽  
Quality Of Care ◽  
Metastatic Breast Cancer ◽  
Accurate Determination ◽  
Metastatic Breast ◽  
Base Case ◽  
Test Results ◽  
The Impact

150 Background: Anti-angiogenesis (AA) drugs (e.g., bevacizumab) are expensive and their clinical benefit in metastatic breast cancer (MBC) has been challenged. Healthcare reform and financial pressures prioritize programs which improve patient quality of care and reduce costs of unnecessary care. Angiogenesis-specific imaging tests (A-IT) under development have potential to offer earlier, accurate determination of response. For A-IT-identified responders, AA treatment would be continued. For patients identified as non-responders, futile AA treatment and associated toxicities can be avoided and alternative therapies initiated. Methods: A decision-tree model was developed to estimate the impact of A-IT from determination of AA therapy eligibility through to disease progression. Key decision nodes were presence/absence of A-IT (assessing change in biomarker expression across 2 PET/CT scans: at AA eligibility, then after one cycle of AA), A-IT sensitivity/specificity (SE/SP) and clinician adherence to test results (tied to belief that results are valid enough to stop AA therapy). Key model inputs (and base case values): 1) median time to progression (TTP) for current MBC patients on AA therapies (9.5 months); 2) median TTP for A-IT identified responders (13 months); 3) costs of bevacizumab, one cycle ($5,200); 4) percentage of AA patients with hemorrhage (4%); 5) costs of hemorrhaging, per event ($14,694); 6) per patient costs for A-IT ($6,000); 7) estimated SE/SP of A-IT – 95%/75%; and 8) clinician adherence to test results (75%). Results: Based on a cohort of 100 MBC patients, use of A-IT results in 29 patients avoiding futile AA therapy with a saving of $460,000, versus a scenario where A-IT was not used. One-way threshold sensitivity analysis shows A-IT is cost-saving if SP >62% or when clinician adherence is ≥63%; results are not sensitive to AA hemorrhage rate. Conclusions: Use of A-IT could improve quality of care by optimizing AA therapy, i.e., by identifying responders who will experience survival benefit and non-responders who can avoid futile therapy and toxicity risks. Significant cost savings may be possible as a result of early determination of response to AA drugs.

Defect concentration and Δn change in light- and elevated temperature- induced degradation

2021 ◽  
Author(s):  
Moonyong Kim ◽  
Matthew Wright ◽  
Daniel Chen ◽  
Catherine Chan ◽  
Alison Ciesla ◽  
...  
Keyword(s):  
Surface Passivation ◽  
Defect Density ◽  
Accurate Determination ◽  
Defect Concentration ◽  
Doping Density ◽  
Lifetime Analysis ◽  
Materials Used ◽  
New Formulation ◽  
The Impact

Abstract The wide variety of silicon materials used by various groups to investigate LeTID make it difficult to directly compare the defect concentrations (Nt) using the typical normalised defect density (NDD) metric. Here, we propose a new formulation for a relative defect concentration (β) as a correction for NDD that allows flexibility to perform lifetime analysis at arbitrary injection levels (Δn), away from the required ratio between Δn and the background doping density (Ndop) for NDD of Δn/N dop = 0.1. As such, β allows for a meaningful comparison of the maximum degradation extent between different samples in different studies and also gives a more accurate representative value to estimate the defect concentration. It also allows an extraction at the cross-over point in the undesirable presence of iron, or flexibility to reduce the impact of modulation in surface passivation. Although the accurate determination of β at a given Δn requires knowledge of the capture cross-section ratio (k), the injection-independent property of the β formulation allows a self-consistent determination of k. Experimental verification is also demonstrated for boron-oxygen related defects and LeTID defects, yielding k-values of 10.6 ± 3.2 and 30.7 ± 4.0, respectively, which are within the ranges reported in the literature. With this, when extracting the defect density at different Δn ranging between 1014 /cm3 to 1015 /cm3 with Ndop = 9.1 ×1015 /cm3, the error is less than 12% using β, allowing for a greatly improved understanding of the defect concentration in a material.

scholarly journals Targeted LC-MS/MS platform for the comprehensive determination of peptides in the kallikrein-kinin system

2021 ◽  
Author(s):  
Tanja Gangnus ◽  
Bjoern B. Burckhardt
Keyword(s):  
Healthy Volunteers ◽  
Clinical Symptoms ◽  
Matrix Effects ◽  
Accurate Determination ◽  
Kinin System ◽  
Carry Over ◽  
Kallikrein Kinin System ◽  
The Impact

AbstractThe kallikrein-kinin system (KKS) is involved in many physiological and pathophysiological processes and is assumed to be connected to the development of clinical symptoms of angioedema or COVID-19, among other diseases. However, despite its diverse role in the regulation of physiological and pathophysiological functions, knowledge about the KKS in vivo remains limited. The short half-lives of kinins, their low abundance and structural similarities and the artificial generation of the kinin bradykinin greatly hinder reliable and accurate determination of kinin levels in plasma. To address these issues, a sensitive LC-MS/MS platform for the comprehensive and simultaneous determination of the four active kinins bradykinin, kallidin, des-Arg(9)-bradykinin and des-Arg(10)-kallidin and their major metabolites bradykinin 2-9, bradykinin 1-7 and bradykinin 1-5 was developed. This platform was validated according to the bioanalytical guideline of the US Food and Drug Administration regarding linearity, accuracy, precision, sensitivity, carry-over, recovery, parallelism, matrix effects and stability in plasma of healthy volunteers. The validated platform encompassed a broad calibration curve range from 2.0–15.3 pg/mL (depending on the kinin) up to 1000 pg/mL, covering the expected concentrations in disease states. No source-dependent matrix effects were identified, and suitable stability of the analytes in plasma was observed. The applicability of the developed platform was proven by the determination of endogenous levels in healthy volunteers, whose plasma kinin levels were successfully detected in the low pg/mL range. The established platform facilitates the investigation of kinin-mediated diseases (e.g. angioedema, COVID-19) and enables the assessment of the impact of altered enzyme activities on the formation or degradation of kinins. Graphical abstract

The Impact of Tube Plugging on Closed Feedwater Heater Operation and Maintenance

1987 ◽  
Vol 109 (2) ◽  
pp. 212-218 ◽  
Author(s):  
F. H. Linley
Keyword(s):  
Good Practice ◽  
Accurate Determination ◽  
Corrective Action ◽  
Nondestructive Examination ◽  
Secondary Damage ◽  
The Face ◽  
Tube Plugging ◽  
The Impact ◽  
Individual Tube

Failures of tubes in closed feedwater heaters are due to localized thermal, mechanical and chemical processes, in combination with the susceptibility of the tube material involved. Experience has demonstrated that changes in operating practice such as feedwater chemistry, frequency of exposure to atmosphere on shutdown and other factors often modify the environmental conditions and introduce unanticipated causes of tube failure. Good practice calls for immediate corrective action, whenever tubes fail, to arrest extension of the problem. Such corrective action is based on an accurate determination of the location of each failure with respect to the tube pass, position in the tube field and distance from the face of the tubesheet. Nondestructive examination and individual tube hydro test of adjacent and other suspect tubes for incipience of failure is required, including the examination of failure specimens, if they can be recovered. More than one failure mechanism may be in process in a heater and no problem potential should be treated casually. Analysis of tube plugging should consider the affect of each failure on heater performance and other equipment in the system, the probability of chronic, continuing failures and the ultimate number of tubes that can be plugged before plant capacity is curtailed. Once the tubes that should be plugged have been determined, plugging systems and installation techniques must also be addressed, with emphasis on preventing secondary damage from failed tubes and the avoidance of any failure caused by the plugs themselves.

scholarly journals VIII.—On Impact

1892 ◽  
Vol 36 (1) ◽  
pp. 225-252 ◽  
Author(s):  
Tait
Keyword(s):  
Accurate Determination ◽  
Golf Ball ◽  
Complete Proof ◽  
Permanent Record ◽  
The Impact ◽  
Made In

The present inquiry is closely connected with some of the phenomena presented in golf:—especially the fact that a ball can be “jerked” nearly as far as it can be “driven.” For this, in itself, furnishes a complete proof that the duration of the impact is exceedingly short. But it does not appear that any accurate determination of the duration can be made in this way. Measurements, even of a rude kind, are impracticable under the circumstances.In 1887 I made a number of preliminary experiments with the view of devising a form of apparatus which should trace a permanent record of the circumstances of impact. I found that it was necessary that one of the two impinging bodies should be fixed:—at least if the apparatus were to be at once simple and manageable. This arrangement gives, of course, a result not directly comparable with the behaviour of a golf-ball. For pressure is applied to one side only, both of ball and of club; but when one of two impinging bodies is fixed it is virtually struck simultaneously on both sides.

scholarly journals The influence of channel network silting up at Žitný Ostrov to range of interaction between surface and groundwater

2020 ◽  
pp. 23-31
Author(s):  
Renáta Dulovičová ◽  
Yvetta Velísková
Keyword(s):  
Surface Water ◽  
Hydraulic Conductivity ◽  
Field Measurements ◽  
Saturated Hydraulic Conductivity ◽  
Water Levels ◽  
Channel Network ◽  
Undisturbed Samples ◽  
The Impact ◽  
Surface And Groundwater

The movement of water resources, especially the possibilities of their regulation by interaction between surface and groundwaters are the subject matter of attention particularly during the occurrence of extreme hydrologic situation. This work presents the overview of knowledge and results which were achieved at IH SAS in this question. It can show the ways how to optimize the adjudicated processes which emerge during the requirement of emergency intervention. The solution of this task was located at the Žitný Ostrov area because this territory with their existence of channel network is suitable for studying the surface and groundwater interaction. The channel network at Žitný Ostrov was built up for drainage and also to safeguard irrigation water. The water level in the whole channel network system has an effect on groundwater level on the Žitný Ostrov and vice versa. It was been necessary to judge the impact of the channel network silting up by bed silts on the interaction between channel network and groundwater on the Žitný Ostrov. The aim was to evaluate the changes of bed silt state of Žitný Ostrov channel network and consecutively their influence on interaction processes between groundwater and surface water along the channels in the period from 1993 to present. The measurements of bed silt thickness in Žitný ostrov channel network had been started from1993, later they continued at selected profiles of three main channels – channel Gabčíkovo-Topoľníky, Chotárny channel and Komárňanský channel (for checking of the silting up variability). From 2008 the detailed field measurements of cross-section profiles aggradations along these selected three channels have been started. The objective of detailed field measurements was the determination of the silt permeability which is expressed by parameter of saturated hydraulic conductivity. This parameter was determined by two ways – as the saturated hydraulic conductivity obtained from disturbed samples of silt Kp and as the saturated hydraulic conductivity obtained from undisturbed samples of silt Kn. In the first case the granularity of silts was determined as a first step and then was computed their Kp from the empirical formulas according Bayer-Schweiger and Spacek. From undisturbed samples of silts which were extracted along the channels from top, middle and bottom layer of silts, were determined the values Kn by the laboratory falling head method. The valid values Kp on channel Gabčíkovo-Topoľníky ranged from 4,33 10-7 to 4,46.10-5 m s-1, on Chotárny channel from 5.98 10-5 to 2.14 10-6 m s-1 and on Komárňanský channel fluctuated from 1.93 10-6 – 6.09 10-5 m s-1. The valid values Kn on on channel Gabčíkovo-Topoľníky ranged from 5.21 10-8 – 4.18 10-3 m s-1 , on Chotárny channel ranged from 8.54 10-8 – 2.70 10-4 m s-1 and on Komárňanský channel fluctuated from 4.72 10-7 – 1.26 10-5 m s-1. The remarkable results were noticed by comparison of values of saturated hydraulic conductivity from disturbed and undisturbed samples Kp and Kn. On Chotárny channel the values of silt saturated hydraulic conductivity from undisturbed samples Kn approximately hundredfold decreased (from 10-6 to 10-8 m s-1). On Komárňanský channel the comparison of values Kp and Kn shown that the values Kn from undisturbed samples approximately tenfold descended against Kp. Simultaneously, the bed silts‘ impact on the groundwater recharge (saturated hydraulic conductivity of silt) was also examined. Determination of the total recharge amount was done by numerical simulation (model SKOKY) and by the so-called method of interaction formulas. These two approaches were applied at the Žitný Ostrov channel network. There were field measurements performed in monitored three main channels and adjacent to obtain correct input data. These characteristics were used for simulation and computation of total recharge along the channels. The total recharge amount was calculated for four alternatives of the surface water levels in the channel and the surroundings groundwater respectively. We chose four simplified variants with the same geological conditions in surroundings area of channels, only water levels of groundwater and in channels were modified. The results of the simulations seem to show greater impact of the silt in the case of outflow from the channels to the surroundings than the inflow into the channel from the surroundings.  

Piston dynamics analysis considering skirt-liner dynamic clearance

2019 ◽  
Vol 233 (13) ◽  
pp. 3538-3553 ◽  
Author(s):  
Jingyi Tian ◽  
Huihua Feng ◽  
Yuanjie Feng ◽  
Zhengwei Yang ◽  
Chengjun Zhu ◽  
...  
Keyword(s):  
Simulation Model ◽  
High Frequency ◽  
Thermal Deformation ◽  
Structural Parameters ◽  
Accurate Determination ◽  
Low Noise ◽  
Dynamics Analysis ◽  
Piston Skirt ◽  
The Impact

Piston slap force is one of the main sources of mechanical engine noise. To obtain a more accurate determination of the piston slap force and minimize piston slap noise, a new simulation model that considers dynamic clearance of the piston skirt and liner has been established in this study. The skirt-liner dynamic clearance is caused mainly by the elastic deformation and thermal deformation of the piston. Comparing three different models, it was found that the impact of dynamic clearance on the piston slap force is reflected mainly in the medium-high frequency, which is the sensitive frequency of the slap noise. Therefore, it is necessary to consider dynamic clearance in the simulation model. In addition, the mechanisms behind the dynamic clearance effect on fluid lubrication, piston dynamics, and piston slap noise were observed. In particular, three typical structural parameters in piston dynamics (the piston pin offset, piston-liner clearance, and piston skirt profile) were studied. The analyses provide guidance for the design of low-noise engines.

scholarly journals Effective approach to epidemic containment using link equations in complex networks

2018 ◽  
Vol 4 (12) ◽  
pp. eaau4212 ◽  
Author(s):  
Joan T. Matamalas ◽  
Alex Arenas ◽  
Sergio Gómez
Keyword(s):  
Complex Networks ◽  
Large Scale ◽  
Accurate Determination ◽  
Air Transportation ◽  
Disease Spread ◽  
Epidemic Spreading ◽  
Critical Thresholds ◽  
Full Structure ◽  
The Impact

Epidemic containment is a major concern when confronting large-scale infections in complex networks. Many studies have been devoted to analytically understand how to restructure the network to minimize the impact of major outbreaks of infections at large scale. In many cases, the strategies are based on isolating certain nodes, while less attention has been paid to interventions on the links. In epidemic spreading, links inform about the probability of carrying the contagion of the disease from infected to susceptible individuals. Note that these states depend on the full structure of the network, and its determination is not straightforward from the knowledge of nodes’ states. Here, we confront this challenge and propose a set of discrete-time governing equations that can be closed and analyzed, assessing the contribution of links to spreading processes in complex networks. Our approach allows a scheme for the containment of epidemics based on deactivating the most important links in transmitting the disease. The model is validated in synthetic and real networks, yielding an accurate determination of epidemic incidence and critical thresholds. Epidemic containment based on link deactivation promises to be an effective tool to maintain functionality of networks while controlling the spread of diseases, such as disease spread through air transportation networks.

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