scholarly journals Probabilistic Characterization of the Vegetated Hydrodynamic System Using Non-Parametric Bayesian Networks

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 398
Author(s):  
Muhammad Hassan Khan Niazi ◽  
Oswaldo Morales Nápoles ◽  
Bregje K. van Wesenbeeck
Keyword(s):  
Salt Marshes ◽  
Numerical Models ◽  
Adaptive Strategy ◽  
Quantitative Information ◽  
System Level ◽  
Successful Implementation ◽  
Probabilistic Description ◽  
Probabilistic Characterization ◽  
Generalized Knowledge ◽  
Hydrodynamic Systems

The increasing risk of flooding requires obtaining generalized knowledge for the implementation of distinct and innovative intervention strategies, such as nature-based solutions. Inclusion of ecosystems in flood risk management has proven to be an adaptive strategy that achieves multiple benefits. However, obtaining generalizable quantitative information to increase the reliability of such interventions through experiments or numerical models can be expensive, laborious, or computationally demanding. This paper presents a probabilistic model that represents interconnected elements of vegetated hydrodynamic systems using a nonparametric Bayesian network (NPBN) for seagrasses, salt marshes, and mangroves. NPBNs allow for a system-level probabilistic description of vegetated hydrodynamic systems, generate physically realistic varied boundary conditions for physical or numerical modeling, provide missing information in data-scarce environments, and reduce the amount of numerical simulations required to obtain generalized results—all of which are critically useful to pave the way for successful implementation of nature-based solutions.

Function-Based Analysis and Redesign of a Flyable Electromechanical Actuator Test Stand

2010 ◽  
Author(s):  
Michael T. Koopmans ◽  
Irem Y. Tumer
Keyword(s):  
Test Stand ◽  
Remaining Useful Life ◽  
System Level ◽  
Successful Implementation ◽  
Functional Modeling ◽  
Electromechanical Actuators ◽  
Design Changes ◽  
Effective System ◽  
Data Output ◽  
Useful Life

Critical faults prevent electromechanical actuators (EMAs) from controlling primary flight surfaces aboard commercial and military human air/spacecraft. However, the efficiency and simplicity of the EMAs makes them appealing for use. For successful implementation, diagnostic and prognostic techniques identifying these critical faults must be optimized. This paper builds the foundation for the design of a second-generation test stand whose aim is to inject known EMA faults and record the data output while onboard an aircraft. First, an overview of faults is presented. Next, functional modeling is introduced as an effective system level representation to implement early design changes. Specifically, functional modeling is proposed to isolate functions of the test stand that can affect faulted and nominal actuator data collection through violations of post-processing statistical assumptions. The data collected from the EMA test stand will be used for actuator prognostic purposes and therefore must closely represent a full-scale actuator installation. This methodology will increase experiment validity, verifiable conclusions made regarding actuator remaining useful life, and overall system reliability.

Impact of salt marsh and seagrass beds on the sediemnt buget and resilience of coatsal areas

2020 ◽  
Author(s):  
Nicoletta Leonardi ◽  
Carmine Donatelli ◽  
Xiahoe Zhang ◽  
Neil Ganju ◽  
Sergio Fagherazzi
Keyword(s):  
Salt Marsh ◽  
Water Resources ◽  
Salt Marshes ◽  
Numerical Models ◽  
Sediment Budget ◽  
Coastal Protection ◽  
Seagrass Beds ◽  
Geophysical Research ◽  
Coastal System ◽  
Depositional Patterns

<p>Salt marshes and seagrass beds can offer sustainable coastal protection solutions and several ecosystem co-benefits. The delicate balance regulating salt marsh stability depends on several factors including the sediment added to and removed from the coastal system (<em>Donatelli et al., 2018, 2019; Zhang et al., 2019</em>).  Despite the importance of these sediment budget dynamics, many feedbacks between salt marsh presence and sediment availability are still unclear. Here, we use numerical models to simulate changes in depositional patterns of six estuaries along the U.S. coastline to investigate how salt marsh and seagrass beds removal and restoration can alter the sediment budget and resilience of coastal environments. </p><p><em>Donatelli, C., Ganju, N.K., Kalra, T.S., Fagherazzi, S. and Leonardi, N., 2019. Changes in hydrodynamics and wave energy as a result of seagrass decline along the shoreline of a microtidal back-barrier estuary. Advances in Water Resources, 128, pp.183-192.</em></p><p><em>Zhang, X., Leonardi, N., Donatelli, C. and Fagherazzi, S., 2019. Fate of cohesive sediments in a marsh-dominated estuary. Advances in water resources, 125, pp.32-40.</em></p><p><em>Donatelli, C., Ganju, N.K., Fagherazzi, S. and Leonardi, N., 2018. Seagrass impact on sediment exchange between tidal flats and salt marsh, and the sediment budget of shallow bays. Geophysical Research Letters, 45(10), pp.4933-4943.</em></p>

Implementation of Phase Change in Numerical Models of Heat Transfer

1983 ◽  
Vol 105 (4) ◽  
pp. 431-435 ◽  
Author(s):  
L. J. Hayes ◽  
K. R. Diller
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Latent Heat ◽  
Numerical Models ◽  
Grid Point ◽  
Nodal Point ◽  
Element Model ◽  
Biological Tissues ◽  
Temperature Fields ◽  
Successful Implementation

This paper investigates some of the numerical problems involved in simulating heat transfer in porous media in the presence of phase change. Applications of this type of simulation include modeling of certain metal forming processes, of biological tissues and organs during cryosurgery or cyropreservation, and of heat transfer in frozen soils subjected to transient environmental conditions. A two-dimensional finite element model was used in which the latent heat is treated directly as an energy source in the problem formulation. Several parameters addressed in this work are crucial to the successful implementation of numerical methods for nonlinear heat transport with phase change, including: the effect of nodal point spacing on the occurrence and magnitude of numerical oscillations in the temperature solution and the use of grid point spacing to control these oscillations; the limiting element size which should be used in order to insure stable temperature fields; and the effect which the range of temperatures over which latent heat is liberated has on the solution. The results indicate that numerical stability is achieved for combinations of the foregoing parameters which yield small values of the Stefan number.

Distribution des populations d'Artemia et de leur parasite Flamingolepis liguloides (Cestode, Cyclophyllidea), dans les salins du littoral méditerranéen français

1990 ◽  
Vol 68 (10) ◽  
pp. 2199-2204 ◽  
Author(s):  
Alain Thiéry ◽  
Florence Robert ◽  
Claude Gabrion
Keyword(s):  
Population Density ◽  
Intermediate Host ◽  
Salt Marshes ◽  
Adaptive Strategy ◽  
Mediterranean Coast ◽  
Infected Host

The occurrence of the cysticercoïd stage of the bird tapeworm Flamingolepis liguloïdes (Cestoda, Cyclophyllidea) was studied across the salt marshes of the French Mediterranean coast. It was observed in 11 populations of the intermediate host Artemia (Crustacea, Anostraca) and investigated. A relationship between the prevalence of the parasite in Artemia and the population density of flamingoes on the sites studied is shown by the results. Parasitism in the infected host populations increases with the size of Artemia. Cysticercoïds are found in the thorax of juvenile Artemia, whereas they are packed in the abdomen in the adults. During growth of Artemia, the localisation of parasites is related to allometric changes in the thorax/abdomen proportion. In infected populations, up to 22.8% of Artemia are red coloured and present an altered behaviour. These physiological and ethological changes are discussed in terms of adaptive strategy by the parasite.

Slip System Interaction Matrix and its Influence on the Macroscopic Response of Al Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 566-571 ◽  
Author(s):  
Mikhail Khadyko ◽  
Stéphane Dumoulin ◽  
Odd Sture Hopperstad
Keyword(s):  
Dislocation Density ◽  
Slip System ◽  
Numerical Models ◽  
Internal Variable ◽  
Relative Strength ◽  
Al Alloys ◽  
System Level ◽  
Interaction Matrix ◽  
Slip Systems ◽  
Crystal Plasticity Theory

In numerical models based on the crystal plasticity theory, various rules are implemented to describe hardening on the slip system level. The rules used are often variations of the Mecking-Kocks law, where the statistically stored dislocation density is the single internal variable. The dislocation density evolution equation consists of two terms representing accumulation and annihilation of dislocations. The accumulation term depends on a scalar parameter and an interaction matrix, which describes the contribution of all slip systems to the accumulation of the dislocations on a given slip system. Physically this matrix represents the relative strength of various dislocation locks which form when dislocations from different slip systems interact. The numerical values of the elements of the interaction matrix are rather hard to establish, but this has been done experimentally for different alloys and also based on numerical simulations. The obtained values, found in literature, are very different from each other. We use some new experimental data in an attempt to establish the influence of the numerical values of the elements of the interaction matrix on the hardening of a polycrystal.

Utilization of Dependency Structure Matrix Analysis to Assess Complex Project Designs

2002 ◽  
Author(s):  
Timothy K. Brady
Keyword(s):  
Analytical Framework ◽  
Matrix Analysis ◽  
System Level ◽  
Successful Implementation ◽  
Project Implementation ◽  
Holistic View ◽  
Structure Matrix ◽  
Dependency Structure ◽  
Dependency Structure Matrix ◽  
The Impact

This paper describes a framework for evaluating the long-term effect of early project implementation decisions. Early decisions, such as establishing the system architecture and selecting technology of particular maturity, can have lasting impact throughout the project development process and during the project’s operations phase. A systems engineering analysis framework using two different extensions of dependency structure matrix (DSM) analysis was developed to provide a comprehensive system view of the project architecture and the technology choices. An “interface DSM” mapped the dependence of components on one another and identified the impact of component criticality on the project’s operations. A “technology risk DSM” included a component technology risk factor to help identify the patterns of system level risk. This analytical framework can be used to expand the design and management teams’ holistic view of the project, which can be used to enhance project implementation decision-making. The analytical framework described in this paper was applied to two spacecraft projects, which served as case studies. Analytical observations were compared to post-project lessons learned to develop a general understanding of the relationship between the critical elements of each project’s structure and the successful implementation approach for each case.

Scaling Up Research-based Educational Practices

Education ◽  
2020 ◽  
Author(s):  
Cathy Wylie ◽  
Jo MacDonald
Keyword(s):  
Educational Research ◽  
Teaching And Learning ◽  
Educational Achievement ◽  
Scaling Up ◽  
School Level ◽  
System Level ◽  
Successful Implementation ◽  
Whole School Reform ◽  
Whole School ◽  
Research Based Practices

Scaling up innovations whose use has resulted in improvements in teaching and learning has been a growing field in educational research and practice in recent decades. Interest has two main spurs: the evident gap between educational research findings and their take-up and use to improve teaching and learning, and the persistent challenges of ensuring high levels of educational achievement for all. Scaling up was originally conceived in terms of numbers: the spread of proven practice from the original sites to many schools, or across a whole system. Scaling up innovation began with testing research-based designs and evaluating their efficacy, followed by implementation. Successful implementation of research-based practices meant attention to fidelity, and thus to constructing materials, guides, and processes, and to providing support from the original designers. In turn this meant more attention to understanding variations in how well schools implemented an intervention: was it due to school-level factors, district- or system-level factors, the nature of the student population, or factors associated with the intervention? There are some enduring programs or interventions that fit this model, some based on whole-school reform, some on particular curriculum areas or approaches. Other interventions have been less successful. More recently, scaling-up work has also included research-educator-administrator partnerships and networks, using improvement design cycles, learning from variability, and expecting that innovations will evolve and be adapted in different contexts, rather than replicated. There has also been increasing attention paid in this branch of scaling-up work to building in ongoing attention to evidence of efficacy, and plan-do-study-review cycles into professional identity and practice, in order to strengthen teacher, network, and school and administration capability, as well as agency, ownership, and community. Most countries have evaluations of innovative programs or approaches showing gains for teaching and learning that failed to take hold or endure. Often this is because of structural reasons beyond the agency or control of those involved, due to changes of government or system decision makers. Other key obstacles are evident in the lack of change in the constraints around how teachers and schools can work. These constraints include competing calls on time, rigid accountabilities and ways resources can be used, expectations of immediate large gains, and mismatched measures of student achievement. There are too many such evaluations for this bibliography to cover. However, key articles that discuss these core challenges to scaling up well-founded research-based practices are included.

Aligning Organizational Culture and Infrastructure to Support Evidence-Based Practice

2020 ◽  
Vol 40 (3) ◽  
pp. 59-63
Author(s):  
Kristina Ost ◽  
Casey Blalock ◽  
Mary Fagan ◽  
Kathleen M. Sweeney ◽  
Suzan R. Miller-Hoover
Keyword(s):  
Organizational Culture ◽  
Evidence Based Practice ◽  
Standard Of Care ◽  
Outcome Evaluation ◽  
Integrated System ◽  
System Level ◽  
Successful Implementation ◽  
Evidence Based ◽  
Development Education ◽  
Quality Patient Care

Standardized nursing practice based on the foundations of evidence-based practice leads to high-quality patient care and optimal outcomes. Despite knowing the benefits of evidence-based practice, health care organizations do not consistently make it the standard of care; thus, implementation of evidence-based practice at the system level continues to be challenging. This article describes the process adopted by a facility in the Southwest that took on the challenge of changing the organizational culture to incorporate evidence-based practice. The organization met the challenges by identifying perceived and actual barriers to successful implementation of evidence-based practice. The lack of standardized practice was addressed by developing a group of stakeholders including organizational leaders, clinical experts, and bedside providers. Changing the culture required a comprehensive process of document selection and development, education, and outcome evaluation. The ultimate aim was to implement an integrated system to develop practices and documents based on the best evidence to support patient outcomes.

Reservoir characterization using crosswell electromagnetic inversion: A feasibility study for the Snorre field, North Sea

Geophysics ◽  
2001 ◽  
Vol 66 (4) ◽  
pp. 1177-1189 ◽  
Author(s):  
G. M. Hoversten ◽  
G. A. Newman ◽  
H. F. Morrison ◽  
E. Gasperikova ◽  
John‐Inge Berg
Keyword(s):  
Electrical Conductivity ◽  
North Sea ◽  
Reservoir Characterization ◽  
Water Saturation ◽  
Numerical Models ◽  
Random Noise ◽  
High Sensitivity ◽  
Quantitative Information ◽  
Two Dimensional ◽  
Reservoir Geometry

The spatial resolution of a commercially available crosswell electromagnetic (EM) system is demonstrated using models derived from three time steps from a reservoir simulation of the Snorre field in the North Sea. The numerical simulation of the Snorre field waterflood shows that crosswell EM field measurements provide high sensitivity to changes in the reservoir over time. This sensitivity is achieved by combining the reservoir geometry derived from surface 3‐D seismic interpretation, reservoir conductivities at well locations, and constrained EM inversion of the reservoir’s electrical conductivity. Inversions of 2‐D and 3‐D numerical models show that the changes in electrical conductivity attributable to changes in water saturation can be quantitatively mapped as a function of time. The inversions provide smooth estimates of the spatial variation of reservoir electrical conductivity that can discriminate between the level of water saturation at different stages of the waterflood. Inversions performed on 2‐D data show that for the Snorre example, 3%–5% Gaussian random noise (depending on the model) can be added without a significant degradation in the inverse models. Two‐dimensional inversions of the full 3‐D data in the Snorre example can map the vertical average electrical conductivity within the reservoir in the interwell region almost as well as when the model is two dimensional (constant in strike direction). The effect of 3‐D structure does not seriously degrade 2‐D inversion in the Snorre example‐even between wells that lie in a line parallel to structure. A series of 2‐D inversions where various constraints and starting models are used demonstrates the importance of incorporating a priori information in the form of starting models and restricting the inversion domain to the reservoir zone. These tests show that totally unconstrained, smooth inversions of the interwell volume provide very limited quantitative information. However, when the reservoir geometry is constrained by seismic data and starting models are provided by linear interpolation of conductivities at well locations, the reservoir’s vertical average electrical conductivity can be predicted to within a few percent by 2‐D inversion. The snorre field consists of a full‐scale reservoir with interwell spacings that exceed 1 km where previous work has demonstrated the applicability of crosswell EM in shallow reservoirs with well separations on the order of 100 m. The simulations show that, given current transmitter and receiver technology, the magnetic fields could be measured in the Snorre field in steel‐cased wells separated from the transmitter by up to 725 m.

scholarly journals Proposal of a new simplified fluid dynamic model for aerospace servovalves

2019 ◽  
Vol 304 ◽  
pp. 04014
Author(s):  
Matteo D.L. Dalla Vedova ◽  
Pier Carlo Berri
Keyword(s):  
Numerical Model ◽  
Flight Control ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Computational Effort ◽  
Operating Conditions ◽  
System Level ◽  
Simplified Models ◽  
System Level Simulation ◽  
Detailed Computer

Highly detailed computer models are required for design and development of modern flight control systems, capable of emulating with high accuracy the behaviour of on-board equipment. At the same time, different simplified models are needed, specifically intended for operations such as the optimization of preliminary design and the development of diagnostic or prognostic strategies. These simplified models are required to combine sufficient levels of accuracy and reliability with reduced computational costs, to minimize the computational burden associated with prognostic and optimization algorithms. In this work, we focus on electro-hydraulic actuators, since they are critical subsystems in terms of safety and availability of the aircraft. Advanced monitoring and prognostic algorithms require new numerical models, combining an acceptable computational effort with a satisfying ability to simulate their performance and dynamics. To this purpose, this paper proposes a new simplified numerical model of the servovalve fluid-dynamic behaviour. This numerical algorithm, based on a very compact semi-empirical formulation, is intended to take into account in a simplified but sufficiently accurate way several typical effects related to the SV spool geometry and the operating conditions. To evaluate the approximations introduced by this model into a system-level simulation, it has been integrated into a dedicated numerical model simulating a simple electrohydraulic on-board actuator, and compared with a higher fidelity servovalve model.

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