scholarly journals Technical note: On the importance of a three-dimensional approach for modelling the transport of neustic microplastics

Ocean Science ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 717-724 ◽  
Author(s):  
Isabel Jalón-Rojas ◽  
Xiao-Hua Wang ◽  
Erick Fredj
Keyword(s):  
Surface Waters ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Vertical Movement ◽  
Technical Note ◽  
Accurate Estimation ◽  
Mixing Processes ◽  
Transport Modelling ◽  
Coastal System ◽  
Vertical Turbulence

Abstract. Understanding and estimating the distribution and transport of microplastics in marine environments has been recognized as a major global research issue. Most of the existing research on transport modelling has focused on low-density particles floating in surface waters, using a 2-D Lagrangian approach and ignoring the vertical displacement of particles. In this work, we evaluate to what extent the vertical movement of particles within surface waters by mixing processes may affect the horizontal transport and fate of microplastics. The aim is to determine whether a 2-D approach is sufficient for the accurate modelling of neustic-microplastics transport or whether a 3-D approach is necessary. For this purpose, we compare visually and statistically the microplastics transport patterns of three simulations in a coastal system: one using a 2-D approach; and two using a 3-D approach with weak and strong vertical turbulence, respectively. The 2-D simulation roughly reproduced the transport and accumulation patterns, but accurate results required a 3-D approach. This was particularly important for strong vertical turbulence and regions characterized by strong vertical current shear. Moreover, a 2-D approach can lead to errors in the results even with negligible turbulence due to simplifications in the velocity field. A 3-D modelling approach is therefore key to an accurate estimation and prediction of microplastics distribution in coastal systems and consequently for planning mitigation and cleaning programmes.

scholarly journals Technical note: On the importance of a three-dimensional approach for modelling the transport of neustic microplastics

2019 ◽  
Author(s):  
Isabel Jalón-Rojas ◽  
Xiao-Hua Wang ◽  
Erick Fredj
Keyword(s):  
Surface Waters ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Vertical Movement ◽  
Technical Note ◽  
Accurate Estimation ◽  
Mixing Processes ◽  
Transport Modelling ◽  
Coastal System ◽  
Vertical Turbulence

Abstract. Understanding and estimating the distribution and transport of microplastics in marine environments has been recognized as a major global research issue. Most of the existing research on transport modelling has focused on low-dense particles floating in surface waters, using a 2D Lagrangian approach and ignoring the vertical displacement of particles. In this work, we evaluate to what extent the vertical movement of particles within surface waters by mixing processes may affect the horizontal transport and fate of microplastics. The aim is to determinate whether a 2D approach is sufficient for the accurate modelling of neustic-microplastics transport or a 3D approach is necessary. For this purpose, we compare visually and statistically the microplastics transport patterns of three simulations in a coastal system: one using a 2D approach; and two using a 3D approach with weak and strong vertical turbulence, respectively. The 2D simulation roughly reproduced the transport and accumulation patterns, but accurate results required a 3D approach. This was particularly important for strong vertical turbulence and regions characterized by strong vertical current shear. Moreover, a 2D approach can lead to errors in the results even with negligible turbulence due to simplifications in the velocity field. A 3D modelling approach is therefore key to an accurate estimation and prediction of microplastics distribution in coastal systems, and consequently for planning mitigation and cleaning programs.

An innovative prone positioning system for advanced deformity and frailty in complex spine surgery

2020 ◽  
Vol 32 (2) ◽  
pp. 229-234
Author(s):  
Benjamin Kolb ◽  
John Large ◽  
Stuart Watson ◽  
Glyn Smurthwaite
Keyword(s):  
Ankylosing Spondylitis ◽  
Three Dimensional ◽  
Technical Note ◽  
Positioning System ◽  
Prone Positioning ◽  
Economic Implications ◽  
Potential Safety ◽  
Chest Deformity ◽  
Positioning Device ◽  
Skin Quality

The authors present a technical note for a prone positioning system developed to facilitate cervical extension osteotomy for ankylosing spondylitis in the presence of severe deformity and frailty. Chin-on-chest deformity represents one of the most debilitating changes of ankylosing spondylitis. Where the chin-brow angle approaches or exceeds 90°, prone positioning becomes problematic due to the fixed position of the head. Furthermore, the challenge is compounded where physiological deconditioning leads to frailty, and the side effects of medical therapies decrease muscle mass and skin quality. Conventional prone positioning equipment is not able to cater to all patients. A versatile system was developed using a 3D reconstruction to enable a positioning simulation and verification tool. The tool was used to comprehensively plan the perioperative episode, including spatial orientation and associated equipment. Three-dimensional printing was used to manufacture a bespoke positioning device that precisely matched the contours of the patient, reducing contact pressure and risk of skin injury. The authors were able to safely facilitate surgery for a patient whose deformity and frailty may otherwise have precluded this possibility. The system has potential safety and economic implications that may be of significant utility to other institutions engaging in complex spinal surgery.

Automatic weaving method for three-dimensional composite preforms using vision system

2021 ◽  
pp. 004051752098238
Author(s):  
Siyuan Li ◽  
Zhongde Shan ◽  
Dong Du ◽  
Li Zhan ◽  
Zhikun Li ◽  
...  
Keyword(s):  
Relative Position ◽  
Vision System ◽  
Estimation Error ◽  
Three Dimensional ◽  
Fiber Reinforced Composites ◽  
Accurate Estimation ◽  
Digital Manufacturing ◽  
Relative Rotation ◽  
Reinforced Composites ◽  
Main Structure

Three-dimensional composite preform is the main structure of fiber-reinforced composites. During the weaving process of large-sized three-dimensional composite preform, relative rotation or translation between the fiber feeder and guided array occurs before feeding. Besides, the weaving needles can be at different heights after moving out from the guided array. These problems are mostly detected and adjusted manually. To make the weaving process more precise and efficient, we propose machine vision-based methods which could realize accurate estimation and adjustment of the relative position-pose between the fiber feeder and guided array, and make the needles pressing process automatic by recognizing the position of the weaving needles. The results show that the estimation error of relative position-pose is within 5%, and the rate of unrecognized weaving needles is 2%. Our proposed methods improve the automation level of weaving, and are conducive to the development of preform forming toward digital manufacturing.

Spatial Kinematic Analysis of Threaded Fastener Assembly

2005 ◽  
Vol 128 (1) ◽  
pp. 116-127 ◽  
Author(s):  
Stephen Wiedmann ◽  
Bob Sturges
Keyword(s):  
Design Space ◽  
Compliant Mechanisms ◽  
Contact Point ◽  
Three Dimensional ◽  
Vertical Movement ◽  
Initial Contact ◽  
Geometric Problem ◽  
Intelligent Sensor ◽  
Contact State ◽  
Contact Points

Compliant mechanisms for rigid part mating exist for prismatic geometries. A few instances are known of mechanisms to assemble screw threads. A comprehensive solution to this essentially geometric problem comprises at least three parts: parametric equations for nut and bolt contact in the critical starting phase of assembly, the possible space of motions between these parts during this phase, and the design space of compliant devices which accomplish the desired motions in the presence of friction and positional uncertainty. This work concentrates on the second part in which the threaded pair is modeled numerically, and contact tests are automated through software. Tessellated solid models were used during three-dimensional collision analysis to enumerate the approximate location of the initial contact point. The advent of a second contact point presented a more constrained contact state. Thus, the bolt is rotated about a vector defined by the initial two contact points until a third contact location was found. By analyzing the depth of intersection of the bolt into the nut as well as the vertical movement of the origin of the bolt reference frame, we determined that there are three types of contacts states present: unstable two-point, quasi-stable two-point, stable three point. The space of possible motions is bounded by these end conditions which will differ in detail depending upon the starting orientations. We investigated all potential orientations which obtain from a discretization of the roll, pitch, and yaw uncertainties, each of which has its own set of contact points. From this exhaustive examination, a full contact state history was determined, which lays the foundation for the design space of either compliant mechanisms or intelligent sensor-rich controls.

scholarly journals Probe-based three-dimensional confocal laser endomicroscopy of brain tumors: technical note

2018 ◽  
Vol Volume 10 ◽  
pp. 3109-3123 ◽  
Author(s):  
Evgenii Belykh ◽  
Arpan A Patel ◽  
Eric J Miller ◽  
Baran Bozkurt ◽  
Kaan Yağmurlu ◽  
...  
Keyword(s):  
Brain Tumors ◽  
Three Dimensional ◽  
Technical Note ◽  
Confocal Laser Endomicroscopy ◽  
Confocal Laser

scholarly journals Horizontal-vertical movement relationships: Adélie penguins forage continuously throughout provisioning trips

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Javed Riaz ◽  
Sophie Bestley ◽  
Simon Wotherspoon ◽  
Louise Emmerson
Keyword(s):  
Environmental Conditions ◽  
Optimal Foraging ◽  
Three Dimensional ◽  
Spatial Location ◽  
Vertical Movement ◽  
Foraging Activity ◽  
Directed Movement ◽  
Vertical Movements ◽  
Movement Trajectories ◽  
Adélie Penguins

Abstract Background Diving marine predators forage in a three-dimensional environment, adjusting their horizontal and vertical movement behaviour in response to environmental conditions and the spatial distribution of prey. Expectations regarding horizontal-vertical movements are derived from optimal foraging theories, however, inconsistent empirical findings across a range of taxa suggests these behavioural assumptions are not universally applicable. Methods Here, we examined how changes in horizontal movement trajectories corresponded with diving behaviour and marine environmental conditions for a ubiquitous Southern Ocean predator, the Adélie penguin. Integrating extensive telemetry-based movement and environmental datasets for chick-rearing Adélie penguins at Béchervaise Island, we tested the relationships between horizontal move persistence (continuous scale indicating low [‘resident’] to high [‘directed’] movement autocorrelation), vertical dive effort and environmental variables. Results Penguins dived continuously over the course of their foraging trips and lower horizontal move persistence corresponded with less intense foraging activity, likely indicative of resting behaviour. This challenges the traditional interpretation of horizontal-vertical movement relationships based on optimal foraging models, which assumes increased residency within an area translates to increased foraging activity. Movement was also influenced by different environmental conditions during the two stages of chick-rearing: guard and crèche. These differences highlight the strong seasonality of foraging habitat for chick-rearing Adélie penguins at Béchervaise Island. Conclusions Our findings advance our understanding of the foraging behaviour for this marine predator and demonstrates the importance of integrating spatial location and behavioural data before inferring habitat use.

Lee waves in three-dimensional stratified flow

1984 ◽  
Vol 148 ◽  
pp. 97-108 ◽  
Author(s):  
G. S. Janowitz
Keyword(s):  
Stream Function ◽  
Displacement Field ◽  
Three Dimensional ◽  
Frequency Dispersion ◽  
Vertical Displacement ◽  
Function Solution ◽  
Dispersion Surface ◽  
Phase Calculation ◽  
Lee Waves ◽  
The Green Function

The effect of a shallow isolated topography on a linearly stratified, three-dimensional, initially uniform flow in the x-direction is considered. The Green-function solution for the velocity disturbance due to this topography, which is equivalent to that due to a dipole at the origin, is shown to be without swirl, i.e. the velocity disturbance lies strictly in planes passing through the x-axis. Thus this disturbance can be described in terms of a stream function. The asymptotic forms of the wavelike portion of the stream function and the vertical displacement field are obtained. The latter is in agreement with the limited versions due to Crapper (1959). The Gaussian curvature of the zero-frequency dispersion surface is obtained analytically as a step in the stationary-phase calculation. The model is extended to determine the vertical displacement field for an arbitrary shallow topography far downstream. For topographies that are even functions of x and y it is shown that the details of the topography affect the displacement field only in the vicinity of the x-axis. Elsewhere, the amplitude of the displacement is proportional to the net volume of the topography.

“A NOVEL ATTEMPT IN ESTIMATION OF FETAL WEIGHT USING NEW SOFT TISSUE MEASUREMENTS”

2021 ◽  
pp. 1-3
Author(s):  
Sathyan Gnanasigamani ◽  
Sudhakar Vadivel ◽  
Bala Subramaniam ◽  
Sakthivel Raja Ganesan ◽  
Pradeebaa Thiyagarajan ◽  
...  
Keyword(s):  
Birth Weight ◽  
Soft Tissue ◽  
Strong Predictor ◽  
Three Dimensional ◽  
Fetal Weight ◽  
Ultrasound Measurement ◽  
Accurate Estimation ◽  
Tissue Thickness ◽  
Third Trimester ◽  
Soft Tissue Thickness

Background: The Accurate estimation of fetal weight is important in modern obstetrics. Currently, Hadlock's formula is used widely for fetal weight estimation, which includes BPD, AC, FL and HC. The correct plane of measurement of various standard parameters is difcult to obtain especially in third trimester. Hence soft tissue thicknesses of the fetus are tested for correlation with birth weight in this study. Materials & Methods: A prospective observational study conducted among 90 pregnant females referred for Ultrasound examination in the third trimester with an interval from the ultrasound scan to delivery of ≤7 days from 2019 to 2020. Results: The measurements of abdominal, fetal mid-thigh and mid-arm soft tissue thicknesses correlated well with birth weight in a high statistically signicant positive linear relationship. A new regression model developed out of the soft tissue thicknesses(FASTT, FMASTT, FTSTT) correlates better than the Hadlock's model and Sujitkumar Hiwale et al model (For Indian population) based on BPD, HC, AC and FL Conclusion: Ultrasound measurement of soft tissue thickness may prove to be a strong predictor of fetal weight essential for sonographic assessment of pregnancy. They are easy and simple hence fetal soft tissue thickness measurements, both two- and three-dimensional, may prove to be a diagnostic parameter that has as small an error rate as possible, is quick to use and reproducible by different examiners

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