Computational models evaluating the impact of sieve plates and radial water exchange on phloem pressure gradients

The article provides an analysis and justification of the need to take into account the compliance of discs of overlapping and coatings when calculating frames from precast concrete structures. Previously conducted full-scale experiments showed that the rigidity of the precast overlapping with full filling of the seams, in comparison with the monolithic overlapping, decreases by 3-15 times due to the ductility of the joints. The use of refined computational models of structural solutions for frames, which take into account the compliance of the conjugations of elements, makes it possible to trace possible redistribution of efforts. Such an approach when reconstructing, it is possible to optimally select and calculate the enforcement of structure, and on new designing, to increase reliability and / or improve the economic performance of frame buildings. According to the results of analytical studies, formulas were adopted for the parameters that allow one to take into account the overall compliance of overlapping disks and coatings in computational models of building frames. Numerical studies on the computational model of a frame building made it possible to evaluate the effect of accounting for compliance on the stress-strain state of a multi-storey frame.

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Numerical simulation of the impact of an integrated renovation project on the Maowei Sea hydrodynamic environment

Scientific Reports ◽

10.1038/s41598-021-96441-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Cui Wang ◽

Ling Cai ◽

Yaojian Wu ◽

Yurong Ouyang

Keyword(s):

Water Exchange ◽

Land Reclamation ◽

Three Dimensional ◽

Exchange Capacity ◽

Reclamation Project ◽

Hydrodynamic Environment ◽

Sea Area ◽

Water Quality Models ◽

The Impact ◽

Main Factor

AbstractIntegrated renovation projects are important for marine ecological environment protection. Three-dimensional hydrodynamics and water quality models are developed for the Maowei Sea to assess the hydrodynamic environment base on the MIKE3 software with high resolution meshes. The results showed that the flow velocity changed minimally after the project, decreasing by approximately 0.12 m/s in the east of the Maowei Sea area and increasing by approximately 0.01 m/s in the northeast of the Shajing Port. The decrease in tidal prism (~ 2.66 × 106 m3) was attributed to land reclamation, and accounted for just 0.86% of the pre-project level. The water exchange half-life increased by approximately 1 day, implying a slightly reduced water exchange capacity. Siltation occurred mainly in the reclamation and dredging areas, amounting to back-silting of approximately 2 cm/year. Reclamation project is the main factor causing the decrease of tidal volume and weakening the hydrodynamics in Maowei Sea. Adaptive management is necessary for such a comprehensive regulation project. According to the result, we suggest that reclamation works should strictly prohibit and dredging schemes should optimize in the subsequent regulation works.

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Evaluation of a Coupled Model to Predict the Impact of Adaptive Behaviour in the Thermal Sensation of Occupants of Naturally Ventilated Buildings in Warm-Humid Regions

Sustainability ◽

10.3390/su13010255 ◽

2020 ◽

Vol 13 (1) ◽

pp. 255

Author(s):

Luciano C. de Faria ◽

Marcelo A. Romero ◽

Lúcia F. S. Pirró

Keyword(s):

Computational Models ◽

Thermal Sensation ◽

Coupled Model ◽

Adaptive Behaviour ◽

Humid Climate ◽

Clothing Insulation ◽

Tropical Regions ◽

Naturally Ventilated Buildings ◽

Adaptive Behaviours ◽

The Impact

Improving indoor environment quality and making urban centres in tropical regions more sustainable has become a challenge for which computational models for the prediction of thermal sensation for naturally ventilated buildings (NVBs) have major role to play. This work performed analysis on thermal sensation for non-residential NVBs located in Brazilian tropical warm-humid climate and tested the effectiveness of suggested adaptive behaviours to mitigate warm thermal sensation. The research method utilized transient computational fluid dynamics models coupled with a dynamic model for human thermophysiology to predict thermal sensation. The calculated results were validated with comparison with benchmark values from questionnaires and from field measurements. The calculated results for dynamic thermal sensation (DTS) seven-point scale showed higher agreement with the thermal sensation vote than with the predicted mean vote. The test for the suggested adaptive behaviours considered reducing clothing insulation values from 0.18 to 0.32 clo (reducing DTS from 0.1 to 0.9), increasing the air speed in 0.9 m/s (reducing DTS from 0.1 to 0.9), and applying both suggestions together (reducing DTS from 0.1 to 1.3) for five scenarios with operative temperatures spanning 34.5–24.0 °C. Results quantified the tested adaptive behaviours’ efficiency showing applicability to improve thermal sensation from slightly-warm to neutral.

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Braided composite stent for peripheral vascular applications

Nanotechnology Reviews ◽

10.1515/ntrev-2020-0056 ◽

2020 ◽

Vol 9 (1) ◽

pp. 1137-1146

Author(s):

Qingli Zheng ◽

Pengfei Dong ◽

Zhiqiang Li ◽

Ying Lv ◽

Meiwen An ◽

...

Keyword(s):

Computational Models ◽

Surface Coverage ◽

Mechanical Performance ◽

Wire Diameter ◽

Orthogonal Experimental Design ◽

Braided Composite ◽

Nitinol Wire ◽

Radial Strength ◽

Braiding Angle ◽

The Impact

AbstractBraided composite stent (BCS), woven with nitinol wires and polyethylene terephthalate (PET) strips, provides a hybrid design of stent. The mechanical performance of this novel stent has not been fully investigated yet. In this work, the influence of five main design factors (number of nitinol wires, braiding angle, diameter of nitinol wire, thickness and stiffness of the PET strip) on the surface coverage, radial strength, and flexibility of the BCS were systematically studied using computational models. The orthogonal experimental design was adopted to quantitatively analyze the sensitivity of multiple factors using the minimal number of study cases. Results have shown that the nitinol wire diameter and the braiding angle are two most important factors determining the mechanical performance of the BCS. A larger nitinol wire diameter led to a larger radial strength and less flexibility of the BCS. A larger braiding angle could provide a larger radial strength and better flexibility. In addition, the impact of the braiding angle decreased when the stent underwent a large deformation. At the same time, the impact of the PET strips increased due to the interaction with nitinol wires. Moreover, the number of PET strips played an important role in the surface coverage. This study could help understand the mechanical performance of BCS stent and provides guidance on the optimal design of the stent targeting less complications.

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The Impact of an Improved Flaw Model on a Pressurized Thermal Shock Evaluation

Fatigue, Fracture and Damage Analysis, Volume 2 ◽

10.1115/pvp2002-1360 ◽

2002 ◽

Author(s):

T. L. Dickson ◽

F. A. Simonen

Keyword(s):

Thermal Shock ◽

Computational Models ◽

The United States ◽

Pressure Vessels ◽

Pressurized Water ◽

Evaluation Program ◽

Pressurized Thermal Shock ◽

Computational Methodology ◽

The Impact ◽

Flaw Characterization

The current regulations for pressurized thermal shock (PTS) were derived from computational models that were developed in the early-mid 1980s. The computational models utilized in the 1980s conservatively postulated that all fabrication flaws in reactor pressure vessels (RPVs) were inner-surface breaking flaws. It was recognized at that time that flaw-related data had the greatest level of uncertainty of the inputs required for the probabilistic-based PTS evaluations. To reduce this uncertainty, the United States Nuclear Regulatory Commission (USNRC) has in the past few years supported research at Pacific Northwest National Laboratory (PNNL) to perform extensive nondestructive and destructive examination of actual RPV materials. Such measurements have been used to characterize the number, size, and location of flaws in various types of welds and the base metal used to fabricate RPVs. The USNRC initiated a comprehensive project in 1999 to re-evaluate the current PTS regulations. The objective of the PTS Re-evaluation program has been to incorporate advancements and refinements in relevant technologies (associated with the physics of PTS events) that have been developed since the current regulations were derived. There have been significant improvements in the computational models for thermal hydraulics, probabilistic risk assessment (PRA), human reliability analysis (HRA), materials embrittlement effects on fracture toughness, and fracture mechanics methodology. However, the single largest advancement has been the development of a technical basis for the characterization of fabrication-induced flaws. The USNRC PTS-Revaluation program is ongoing and is expected to be completed in 2002. As part of the PTS Re-evaluation program, the updated risk-informed computational methodology as implemented into the FAVOR (Fracture Analysis of Vessels: Oak Ridge) computer code, including the improved PNNL flaw characterization, was recently applied to a domestic commercial pressurized water reactor (PWR). The objective of this paper is to apply the same updated computational methodology to the same PWR, except utilizing the 1980s flaw model, to isolate the impact of the improved PNNL flaw characterization on the PTS analysis results. For this particular PWR, the improved PNNL flaw characterization significantly reduced the frequency of RPV failure, i.e., by between one and two orders of magnitude.

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Stereoscopically Observed Deformations of a Compliant Abdominal Aortic Aneurysm Model

Journal of Biomechanical Engineering ◽

10.1115/1.4005416 ◽

2011 ◽

Vol 133 (11) ◽

Cited By ~ 12

Author(s):

Clark A. Meyer ◽

Eric Bertrand ◽

Olivier Boiron ◽

Valérie Deplano

Keyword(s):

Abdominal Aortic Aneurysm ◽

Aortic Aneurysm ◽

Computational Models ◽

Imaging System ◽

Strain Differences ◽

Cyclic Strain ◽

Experimental Models ◽

Body Motion ◽

Abdominal Aortic ◽

The Impact

A new experimental setup has been implemented to precisely measure the deformations of an entire model abdominal aortic aneurysm (AAA). This setup addresses a gap between the computational and experimental models of AAA that have aimed at improving the limited understanding of aneurysm development and rupture. The experimental validation of the deformations from computational approaches has been limited by a lack of consideration of the large and varied deformations that AAAs undergo in response to physiologic flow and pressure. To address the issue of experimentally validating these calculated deformations, a stereoscopic imaging system utilizing two cameras was constructed to measure model aneurysm displacement in response to pressurization. The three model shapes, consisting of a healthy aorta, an AAA with bifurcation, and an AAA without bifurcation, were also evaluated with computational solid mechanical modeling using finite elements to assess the impact of differences between material properties and for comparison against the experimental inflations. The device demonstrated adequate accuracy (surface points were located to within 0.07 mm) for capturing local variation while allowing the full length of the aneurysm sac to be observed at once. The experimental model AAA demonstrated realistic aneurysm behavior by having cyclic strains consistent with reported clinical observations between pressures 80 and 120 mm Hg. These strains are 1–2%, and the local spatial variations in experimental strain were less than predicted by the computational models. The three different models demonstrated that the asymmetric bifurcation creates displacement differences but not cyclic strain differences within the aneurysm sac. The technique and device captured regional variations of strain that are unobservable with diameter measures alone. It also allowed the calculation of local strain and removed rigid body motion effects on the strain calculation. The results of the computations show that an asymmetric aortic bifurcation created displacement differences but not cyclic strain differences within the aneurysm sac.

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Variability of the water availability in a river lake system – A case study of Lake Symsar

Journal of Water and Land Development ◽

10.1515/jwld-2016-0039 ◽

2016 ◽

Vol 31 (1) ◽

pp. 87-96 ◽

Cited By ~ 2

Author(s):

Angela B. Kuriata-Potasznik ◽

Sławomir Szymczyk

Keyword(s):

Climate Change ◽

Water Availability ◽

Water Retention ◽

Water Exchange ◽

Water Losses ◽

Local Conditions ◽

Local Climate ◽

Lake System ◽

Catchment Areas ◽

The Impact

AbstractIt is predicted that climate change will result in the diminution of water resources available both on global and regional scales. Local climate change is harder to observe and therefore, while counteracting its effects, it seems advisable to undertake studies on pertinent regional and local conditions. In this research, our aim was to assess the impact of a river and its catchment on fluctuations in the water availability in a natural lake which belongs to a post-glacial river and lake system. River and lake systems behave most often like a single interacting hydrological unit, and the intensity of water exchange in these systems is quite high, which may cause temporary water losses. This study showed that water in the analyzed river and lake system was exchanged approx. every 66 days, which resulted from the total (horizontal and vertical) water exchange. Also, the management of a catchment area seems to play a crucial role in the local water availability, as demonstrated by this research, where water retention was favoured by wooded and marshy areas. More intensive water retention was observed in a catchment dominated by forests, pastures and wetlands. Wasteland and large differences in the land elevation in the tested catchment are unfavourable to water retention because they intensify soil evaporation and accelerate the water run-off outside of the catchment. Among the actions which should be undertaken in order to counteract water deficiencies in catchment areas, rational use and management of the land resources in the catchment are most often mentioned.

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An Adaptable Ct-Derived 3D-Printed Alignment Fixture Minimizes Errors in Whole-Bone Biomechanical Testing

Journal of Biomechanical Engineering ◽

10.1115/1.4051433 ◽

2021 ◽

Author(s):

Jordan V. Inacio ◽

DanielleM Cristino ◽

Michael W. Hast ◽

Hannah Dailey

Keyword(s):

Computational Models ◽

Biomechanical Testing ◽

Ct Scanning ◽

Industrial Applications ◽

Long Bone ◽

Implant Design ◽

Orthopaedic Implant ◽

Test Frame ◽

3D Printed ◽

The Impact

Abstract Biomechanical testing of long bones can be subject to undesirable errors and uncertainty due to malalignment of specimens with respect to the mechanical axis of the test frame. To solve this problem, we designed a novel, customizable alignment and potting fixture for long bone testing. The fixture consisted of 3D-printed components modeled from specimen-specific CT scans to achieve a predetermined specimen alignment. We demonstrated the functionality of this fixture by comparing benchtop torsional test results to specimen-matched finite element models and found a strong and statistically significant correlation (R2 = 0.9536, p < 0.001). Additional computational models estimated the impact of malalignment on mechanical behavior in both torsion and axial compression. Results confirmed that torsion testing is relatively robust to alignment artifacts, with absolute percent errors less than 8% in all malalignment scenarios. In contrast, axial testing was highly sensitive to setup errors, experiencing absolute percent errors up to 40% with off-center malalignment and up to 130% with angular malalignment. This suggests that whenever appropriate, torsion tests should be used preferentially as a summary mechanical measure. When more challenging modes of loading are required, pre-test clinical-resolution CT scanning can be effectively used to create potting fixtures that allow for precise pre-planned specimen alignment. This may be particularly important for more sensitive biomechanical tests (e.g. axial compressive tests) that may be needed for industrial applications, such as orthopaedic implant design.

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A Mechanistic Motor-Clutch Model That Explains Cell Shape Dynamics to Cyclic Stretch

Molecular Biology of the Cell ◽

10.1091/mbc.e20-01-0087 ◽

2022 ◽

Author(s):

Benjamin W. Scandling ◽

Jia Gou ◽

Jessica Thomas ◽

Jacqueline Xuan ◽

Chuan Xue ◽

...

Keyword(s):

Computational Model ◽

Computational Models ◽

The Body ◽

Cyclic Stretch ◽

Substrate Stiffness ◽

Cell Alignment ◽

Cellular Mechanisms ◽

Actin Bundles ◽

The Impact

Many cells in the body experience cyclic mechanical loading, which can impact cellular processes and morphology. In vitro studies often report that cells reorient in response to cyclic stretch of their substrate. To explore cellular mechanisms involved in this reorientation, a computational model was developed by utilizing the previous computational models of the actin-myosin-integrin motor-clutch system developed by others. The computational model predicts that under most conditions, actin bundles align perpendicular to the direction of applied cyclic stretch, but under specific conditions, such as low substrate stiffness, actin bundles align parallel to the direction of stretch. The model also predicts that stretch frequency impacts the rate of reorientation, and that proper myosin function is critical in the reorientation response. These computational predictions are consistent with reports from the literature and new experimental results presented here. The model suggests that the impact of different stretching conditions (stretch type, amplitude, frequency, substrate stiffness, etc.) on the direction of cell alignment can largely be understood by considering their impact on cell-substrate detachment events, specifically whether detachment occurs during stretching or relaxing of the substrate.

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Impact of Damping Models in Damage Identification

Shock and Vibration ◽

10.1155/2019/4652328 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12

Author(s):

Michael Souza ◽

Daniel Castello ◽

Ney Roitman ◽

Thiago Ritto

Keyword(s):

Computational Models ◽

Damage Identification ◽

Model Parameters ◽

Posterior Density ◽

Unknown Parameters ◽

Key Issues ◽

Delayed Rejection ◽

Lumped Masses ◽

Aluminum Beam ◽

The Impact

Several damage identification approaches are based on computational models, and their diagnostics depend on the set of modelling hypotheses adopted when building the model itself. Among these hypotheses, the choice of appropriate damping models seems to be one of the key issues. The goal of this paper is to analyze the impact of a set of damping models on the damage identification diagnostics. The damage identification is built on a Bayesian framework, and the measured data are the modal data associated with the first modes of the structure. The exploration of the posterior density of unknown model parameters is performed by means of the Markov chain Monte Carlo method (MCMC) with Delayed Rejection Adaptive Metropolis (DRAM) algorithm. The analyses are based on experimental dynamic response obtained from an aluminum beam instrumented with a set of accelerometers. The presence of damage/anomaly within the system is physically simulated by placing lumped masses over the beam, considering three different masses and two different placing positions. For the set of cases analyzed, it is shown that the proposed approach was able to identify both the position and magnitude of the lumped masses and that the damping models may not provide an increase of knowledge of some unknown parameters when damping rates are lower than 1%.

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