scholarly journals A two‐field geostatistical model combining point and areal observations—A case study of annual runoff predictions in the Voss area

2021 ◽  
Author(s):  
Thea Roksvåg ◽  
Ingelin Steinsland ◽  
Kolbjørn Engeland
Keyword(s):  
Annual Runoff ◽  
Geostatistical Model ◽  
Model Combining

Magnetotelluric static shift: Estimation and removal using the cokriging method

Geophysics ◽  
2007 ◽  
Vol 72 (1) ◽  
pp. F25-F34 ◽  
Author(s):  
Benoit Tournerie ◽  
Michel Chouteau ◽  
Denis Marcotte
Keyword(s):  
Apparent Resistivity ◽  
A Priori ◽  
Shift Factor ◽  
Static Shift ◽  
Geostatistical Model ◽  
Data Set ◽  
Resistivity Sounding ◽  
The Difference ◽  
Cross Variogram

We present and test a new method to correct for the static shift affecting magnetotelluric (MT) apparent resistivity sounding curves. We use geostatistical analysis of apparent resistivity and phase data for selected periods. For each period, we first estimate and model the experimental variograms and cross variogram between phase and apparent resistivity. We then use the geostatistical model to estimate, by cokriging, the corrected apparent resistivities using the measured phases and apparent resistivities. The static shift factor is obtained as the difference between the logarithm of the corrected and measured apparent resistivities. We retain as final static shift estimates the ones for the period displaying the best correlation with the estimates at all periods. We present a 3D synthetic case study showing that the static shift is retrieved quite precisely when the static shift factors are uniformly distributed around zero. If the static shift distribution has a nonzero mean, we obtained best results when an apparent resistivity data subset can be identified a priori as unaffected by static shift and cokriging is done using only this subset. The method has been successfully tested on the synthetic COPROD-2S2 2D MT data set and on a 3D-survey data set from Las Cañadas Caldera (Tenerife, Canary Islands) severely affected by static shift.

Integrated Quality Function Deployment as a Tool for Quality Achievement in Healthcare

2012 ◽  
Vol 1 (2) ◽  
pp. 80-92 ◽  
Author(s):  
Chintala Venkateswarlu ◽  
A. K. Birru
Keyword(s):  
Analytic Hierarchy Process ◽  
Quality Function Deployment ◽  
Healthcare Services ◽  
Relative Importance ◽  
Analytic Hierarchy ◽  
Direct Evaluation ◽  
Quality Function ◽  
Model Combining ◽  
Hierarchy Process

Quality function deployment (QFD) is a methodology that extracts client demands (CDs) and inducting them in the final service/product. Once CDs are extracted from client the traditional QFD approach uses absolute importance to identify the degree of importance for each CD. Direct evaluation of CDs based on absolute weighting without tradeoffs is easy to perform, but may lead to serious deviations from reality. An alternative to avoid this problem is to adopt the analytic hierarchy process (AHP) approach. In this paper, an integrated model combining AHP and QFD has been delineated as a quality achievement tool in healthcare. A case study is performed on the healthcare services provided by government general hospital, Indore District, Madhya Pradesh, India and data has been analyzed to benchmark the proposed framework by computing the degree of relative importance for CDs through AHP and incorporating them in subsequent deployment matrices.

ON MODELING ACTIVITY CRASHING AND OVERLAPPING: A FIRST ALGORITHM

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Kamel Mohamed Elamrousy ◽  
Pablo Ballesteros-Pérez
Keyword(s):  
Construction Projects ◽  
Focal Point ◽  
Model Combining ◽  
Original Plan ◽  
Speed Up ◽  
Significant Compression ◽  
Mixed Approach ◽  
Project Management And Scheduling ◽  
Acceleration Mode

Accelerating construction projects is a commonly used method for meeting the project deadlines and/or compensating for current delays. There are several approaches to speed-up a project, such as activity crashing and overlapping. Activity crashing means reducing activity durations through adding more resources. Activity overlapping means executing certain activities in parallel when they were supposed to be sequential in the original plan. Construction management literature is mostly focused on studying each acceleration mode separately, while the focal point of this paper is to develop a joint model and a first algorithmic implementation that involves both acceleration methods. Particularly, on reviewing the project management and scheduling literature, a mathematical model combining activity crashing and overlapping is reformulated. Also, a Genetic Algorithm is implemented on a fictitious case study. Preliminary findings of the model and algorithmic implementations identify that activity crashing alone and a mixed approach are preferred when significant compression is required, whereas activity overlapping is recommended for minimizing compression costs when only a small compression is required.

scholarly journals A geostatistical spatially varying coefficient model for mean annual runoff that incorporates process-based simulations and short records

2021 ◽  
Author(s):  
Thea Roksvåg ◽  
Ingelin Steinsland ◽  
Kolbjørn Engeland
Keyword(s):  
Hydrological Model ◽  
Annual Runoff ◽  
Data Availability ◽  
Geostatistical Model ◽  
Ungauged Catchments ◽  
Varying Coefficient ◽  
Geostatistical Methods ◽  
Geostatistical Method ◽  
Spatially Varying ◽  
Hbv Model

Abstract. We present a Bayesian geostatistical model for mean annual runoff that incorporates simulations from a process-based hydrological model by treating the simulations as a covariate in the statistical model. The regression coefficient of the covariate is modeled as a spatial field such that the relationship between the covariate (simulations from a hydrological model) and the response variable (observed mean annual runoff) is allowed to vary within the study area. Hence, it is a spatially varying coefficient. A preprocessing step for including short records in the modeling is also suggested and we obtain a model that can exploit several data sources by using state of the art statistical methods. The geostatistical model is evaluated by predicting mean annual runoff for 1981–2010 for 127 catchments in Norway based on observations from 411 catchments. Simulations from the process-based HBV model on a 1 km × 1 km grid are used as input. We found that on average the proposed approach outperformed a purely process-based approach (HBV) when predicting runoff for ungauged and partially gauged catchments: The reduction in RMSE compared to the HBV model was 20 % for ungauged catchments and 58 % for partially gauged catchments, where the latter is due to the preprocessing step. For ungauged catchments the proposed framework also outperformed a purely geostatistical method with a 10 % reduction in RMSE compared to the geostatistical method. For partially gauged catchments however, purely geostatistical methods performed equally well or slightly better than the proposed combination approach. It is not surprising that purely geostatistical methods perform well in areas where we have data. In general, we expect the proposed approach to outperform geostatistics in areas where the data availability is low to moderate.

scholarly journals Continuous Improvements at Operator Level

2020 ◽  
Vol 10 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Jon Lerche ◽  
Hasse Neve ◽  
Søren Wandahl ◽  
Allan Gross
Keyword(s):  
Knowledge Base ◽  
Conceptual Model ◽  
Lean Production ◽  
Empirical Studies ◽  
Fixed Number ◽  
Lean Construction ◽  
Offshore Wind ◽  
Model Combining ◽  
Alternative Processes

AbstractFew empirical studies have previously reported on the implementation of takt planning and utilizing Deming cycles (PDCA) to control construction workflows continuously. This paper presents a case study from the offshore renewable industry, closely related to construction. The paper aims to develop and evaluate a conceptual model combining takt planning and the Deming cycle within the offshore wind construction environment. The conceptual model has through interactions with construction experts been modified for a visual board implementation, covering two alternative processes with a fixed number of technicians per performing team. The knowledge base for the conceptual model is based on Takt planning implementation from the lean construction community and PDCA implementation from the lean production community. The main contribution of this paper is the development and evaluation of the conceptual model combining takt planning and the Deming cycle in a construction environment. This conceptual model has potential implications in the construction and refurbishment industry.

scholarly journals Runoff sensitivity to climate and land-use changes: A case study in the Longtan basin, Southwestern China

2020 ◽  
Author(s):  
Guiyan Mo ◽  
Ya Huang ◽  
Qing Yang ◽  
Dayang Wang ◽  
Chongxun Mo
Keyword(s):  
Land Use ◽  
Water Conservation ◽  
Assessment Tool ◽  
Land Use Changes ◽  
Annual Runoff ◽  
Vegetation Coverage ◽  
Average Annual Runoff ◽  
Annual Evaporation ◽  
Water Assessment

Abstract Based on the scenario hypothesis method, this paper applied a Soil and Water Assessment Tool (SWAT) to analyze the sensitivity of runoff to climate and land-use changes in the Longtan basin, China. Results indicated that (1) for every 1 °C increase in temperature, the average annual runoff decreased by 9.9 mm, and the average annual evaporation increased by 9.3 mm. However, for every 10% increase in rainfall, the average annual runoff and evapotranspiration increased by 96.3 mm and 11.53 mm, respectively. Obviously, runoff was more sensitive to the change in rainfall than temperature in the Longtan basin. Meanwhile, (2) forestland could conserve water resources, but its water consumption was larger. Although grassland played a relatively small role in water conservation, it consumed less water. At the same time, increasing the area of forestland and grassland could weaken peak floods, and the water retention function of vegetation could prevent runoff from increasing and decreasing steeply. Therefore, it is worth improving vegetation coverage.

Using Bayesian geostatistical models to correct gridded hydrological products relative to the actually observed streamflow

2020 ◽  
Author(s):  
Thea Roksvåg ◽  
Ingelin Steinsland ◽  
Kolbjørn Engeland
Keyword(s):  
Linear Relationship ◽  
Gaussian Random Field ◽  
Annual Runoff ◽  
Flow Index ◽  
Geostatistical Model ◽  
Ungauged Catchments ◽  
Geostatistical Methods ◽  
Catchment Areas ◽  
Geostatistical Models ◽  
Input Variables

<p>Conceptual hydrological models are process-based models that are used to simulate flow indices based on physical or empirical relationships and input variables like precipitation, temperature and land use. For many applications the goal is to use the process-based model to construct a gridded map of the flow index of interest, e.g. for mean annual runoff. However, one challenge is that the resulting runoff map does not necessarily fit to the actually observed streamflow data when the grid nodes are aggregated to catchment areas. A solution to this problem is to correct the gridded hydrological product afterwards relative to the actually observed streamflow in areas where we have measurements. In this work, we explore different Bayesian geostatistical tools that can contribute to this correction. We suggest a model where the  observed streamflow is used as a response variable and the gridded hydrological product is used as a covariate. In particular, a geostatistical model with a spatially varying coefficient (SVC) is suggested, and we develop a linear relationship between the response and the covariate that is allowed to vary in the study area. This is achieved by modeling the regression coefficient as a Gaussian random field (GRF) that defines the spatial pattern of the linear relationship. We also test two simpler geostatistical models, and investigate how short records of runoff can be included in the correction procedure. </p><p>The geostatistical models are tested by correcting a gridded mean annual runoff product from the HBV model relative to the observed  mean annual runoff. We use data from around 400 catchments in Norway from 1981-2010. The results show that all three geostatistical methods lead to a considerably better fit between the corrected product and the actually observed streamflow for the gauged catchments, which was our main goal. In addition, we also obtain improved predictions for many of the ungauged catchments in Norway.</p>

Form Defects Consideration in Polytope-Based Tolerance Analysis

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Ting Liu ◽  
Laurent Pierre ◽  
Nabil Anwer ◽  
Yanlong Cao ◽  
Jiangxin Yang
Keyword(s):  
Tolerance Analysis ◽  
Significant Loss ◽  
Minkowski Sum ◽  
Skin Model ◽  
Model Combining ◽  
Perfect Form ◽  
Finite Set ◽  
Physical Shape ◽  
Polytope Model

The polytope-based tolerance analysis in design process uses a finite set of constraints to represent specifications and propagates these constraints to any objective point in the Euclidean space. The operations of Minkowski sum and intersection on polytopes are well suited to serial and parallel assemblies. The polytope model has been applied to complex assemblies which contain a large number of joints and geometrical tolerances. However, the previous studies on this model consider toleranced features as surfaces of perfect form. The ignorance of form defects in tolerance analysis would result in a significant loss in accuracy and reliability. In this paper, an extension of the polytope model for tolerance analysis considering form defects is described in which the skin model shape representing the physical shape of the product is adopted to simulate the actual toleranced feature in place of the substitute one used conventionally. The combination of polytope model and skin model shape is expected to inherit many of the advantages of each model, combining easy-to-use tolerance propagation and form defects representation with accuracy guarantees. To demonstrate the method and its respective application, a case study of an assembly is illustrated in detail. The proposed method further enhances the capability of the polytope model in handling form defects and provides more realistic assembly results that approximate the actual assembly conditions for design evaluation.

scholarly journals Effective Evaluation of Infiltration and Storage Measures in Sponge City Construction: A Case Study of Fenghuang City

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 937 ◽  
Author(s):  
Jinjun Zhou ◽  
Jiahong Liu ◽  
Weiwei Shao ◽  
Yingdong Yu ◽  
Kun Zhang ◽  
...  
Keyword(s):  
Drainage System ◽  
Annual Runoff ◽  
Hunan Province ◽  
Chinese Government ◽  
Control Effect ◽  
Sponge City ◽  
Runoff Control ◽  
City Construction ◽  
And Storage

In recent years, urban waterlogging problems have become more and more serious, which has led to flood disasters in some cities. The Chinese government launched the sponge city pilot construction in 2015 to mitigate the risk of urban flooding and control the runoff in source areas. Rain-runoff control is one of the main indices of a sponge city, thus, evaluating its control effect is essential for sponge city construction. This paper chose Fenghuang city, located in the west of Hunan province, as a case study area to assess the rainwater control effect by using the MIKE FLOOD model. The results showed that: (1) the total annual runoff control rate (TARCR) of sponge city design was a reasonable indicator for daily rainwater control; (2) the goal of Fenghuang Sponge City was close to the 1-year rainfall event; and (3) infiltration and storage measures could reduce but not eliminate urban waterlogging. The capacity of the drainage system should be fundamentally improved to enhance the prevention standards of urban waterlogging.

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