bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Bore Characteristics Using KdV-Based Nonlinear Fourier Transform
Authors: Bruehl Markus , Wahls Sander , Barranco Granged Ignacio , Liu Philipp L.-F.
Published: December 2020

Bores propagating in shallow water transform into undular bores and, finally, into trains of solitons. The observed number and height of these undulations, and later discrete solitons, is strongly dependent on the propagation length of the bore. Empirical results show that the final height of the leading soliton in the far-field is twice the initial mean bore height. The complete disintegration of the initial bore into a train of solitons requires very long propagation lengths, but unfortunately these required distances are usually not available in experimental tests or nature. Therefore, the analysis of the bore decomposition for experimental data into solitons is difficult and requires further approaches. Previous studies have shown that by application of the nonlinear Fourier transform based on the Korteweg–de Vries equation (KdV-NFT) to bores and long-period waves propagating in constant depth, the number and height of all solitons can be reliably predicted already based on the initial bore-shaped free surface.

Against this background, this study presents the systematic analysis of the leading-soliton amplitudes for non-breaking and breaking bores with different strengths in different water depths in order to validate the KdV-NFT results for non-breaking bores, and to show the limitations of wave breaking on the spectral results. The analytical results are compared with data from experimental tests, numerical simulations and other approaches from literature.
Verification and Validation of CFD Uncertainty Analysis Based on SST K-ω Model
Authors: Zhang Li , Chen Weimin , Chen Jianting , Zhou Chuanming
Published: December 2020

CFD uncertainty analysis is a process to quantify the accuracy of numerical simulation results, and it is also a research hotspot in the past decades. ITTC(2017) requires uncertainty analysis of ship CFD simulation results, that is, verification and validation. In this paper, with reference to the recommended procedures by ITTC, the uncertainty of the CFD numerical simulation results of ship model resistance was analyzed. Based on the SST k-ω turbulence model, the Y+ values near the wall were set to 60,120,240, respectively. And for each and Y+ value, three different sets of grid densities were set respectively, and the uncertainty was analyzed. The results show that: 1) the results of Y+ at 60 and 120 were not validated, and the results at 240 was validated, 2) the selection of Y+ value has a significant effect on the numerical results, 3) increasing the mesh density can make the result converge, but it is not sure to get the result with the least error. Through the uncertainty analysis of CFD results, it is helpful to find a method to improve the accuracy of the numerical results.
Stable Triple-Layer Lubricated Pipeline Flow
Authors: Sarmadi Parisa , Hormozi Sarah , Frigaard Ian A.
Published: December 2020

Recently we have introduced a novel methodology for efficient transport of heavy oil via a triple-layer core-annular flow [1]. Pumping pressures are significantly reduced by concentrating high shear rates to a lubricating layer, while ideas from visco-plastic lubrication were used to eliminate interfacial instabilities. We purposefully position a shaped unyielded skin of a visco-plastic fluid between the transported oil and the lubricating fluid layer. The shaping of the skin layer allows for lubrication forces to develop and balance the density difference between the fluids. Here we show an explicit advantage of the proposed method. Essentially the method can give stable flows for a very wide range of fluid input ratio, although not all will produce the desired reduction in frictional pressure losses. Additionally, we use the extensional flow method derived in [2] to estimate the required yield stress to maintain the skin completely unyielded.
Experimental Investigations on the Residual Strength of Corroded Steel-Stiffened Plates
Authors: Park Sang-Hyun , Shin Hyun Kyoung , Kim Jae-Shin , Cho Sang-Rai , Jang Yong-Su , Baek Nam-Ki , Park Dong-Ki
Published: December 2020

In this study, the tensile and compressive behaviours of corroded steel-stiffened plates were experimentally investigated, and the effects of pitting- and grooving-corrosion damage on the residual strengths of corroded stiffened plates were evaluated. Two series of tests were conducted for this study: one involved tensile test on specimens having natural corrosions and artificially machined corrosions, and the other involved compression tests on damaged stiffened plates having artificially machined corrosions. Naturally corroded tensile specimens were obtained from an aged ship. The profiles of the naturally corroded tensile specimens were measured using a three-dimensional (3-D) scanner and a dial thickness gauge. Tensile tests were conducted on nine naturally corroded and fifteen artificially machined specimens. Compression tests were performed on seven stiffened plates having artificially machined corrosion damage. Pitting- and grooving-corrosions were considered in the compression tests. Before these tests, the initial shape imperfections of the stiffened plate models were measured using a 3-D scanning machine. Test results including load-displacement relationship and the ultimate strength under compressive loads were analysed. Finite element (FE) modelling and analyses were performed in this study using commercial software CATIA and ABAQUS. The outputs of numerical analyses were compared with the corresponding test results, and a reasonable agreement between the test results and numerical predictions is shown.
Numerical Simulation and Experiments of Flow-Induced Oscillations of Single-Cylinder With Large Passive Turbulence Control
Authors: Li Ningyu , Park Hongrae , Sun Hai , Bernitsas Michael M.
Published: December 2020

Passive turbulence control (PTC) is being used in the Marine Renewable Energy Laboratory (MRELab) of the University of Michigan to enhance flow induced oscillations (FIO) of cylinders in the VIVACE (Vortex Induced Vibration for Aquatic Clean Energy) Converter. Large PTC triggers VIV and galloping at lower flow speeds for energy harvesting. Currently, FIO of cylinders with large PTC for high Re has received limited attention and, particularly, the effect of variable PTC height on FIO of cylinders. The vast majority of ocean currents, rivers, and tides are too slow for Marine Hydro Kinetic (MHK) energy technologies to harness it. In order to enhance FIO and to initiate galloping earlier, a circular cylinder is geometrically modified using straight strips placed on the cylinder surface symmetrically PTC strips on the cylinder effectively change the flow properties. In the present study, the FIO of a single-cylinder with large PTC, on end linear-springs, is modelled and simulated using a Fluid-Structure Interaction (FSI) code. Results are verified by corresponding experimental data. Results show that VIV onset occurs at lower Re for large-PTC cylinder in comparison with lower-PTC cylinder. Contrary to smooth cylinders for which the amplitude ratio is small in the transition region between VIV and galloping, application of large PTC leads to high amplitude response in the transition region. The mechanism behind this observation is the further departure of the geometry from the smooth circular cylinder. The latter does not exhibit galloping due to flow and geometric symmetry in all directions. Moreover, in the galloping region, the amplitude ratio increases with the height of PTC. Earlier onset of galloping and enhancement of geometric asymmetry support this observation as well.
Systematic Measures to Cope With Offshore Drilling Hazards: An Interpretive Structural Modeling Approach
Authors: Ali Liaqat , Jin Shan , Bai Yong
Published: December 2020

The process of offshore drilling faces several challenges. The process of mixing of water and oil results in issues that lead to the contamination of ocean water. Therefore, this study focuses on the hazards and the measures taken to cover up those hazards of offshore drilling. There are types of offshore drilling hazards such as health hazards and safety hazards. In connection to identify the hazards facing in offshore drilling and taking measures to prevent these hazards, ISM (interpretive structural modeling) technique is used. Data is collected through extensive literature review and by conducting interviews from Japan and China. Experts from academia and industry specialists are approached for interview. Eight important Measures to prevent the hazards due to offshore drilling have been identified. And the relationship among these measures are depicted by constructing SSIM (structural self-interaction matrix). The next step of ISM technique which is reachability matrix, developed which also establish the driving and dependence power of each variable. After reachability matrix a diagram is discussed where the measures are depicted in relation to their dependency, drive and independency levels, which show the influence of each measure with other. This study is valuable in the field of offshore drilling for top managers in decision making and for literature review study. Further, this study has some limitation, if the contributions of experts from other countries would have been exerted in our research that may came up with more measures for the prevention of hazards encounter in Offshore oil drilling. Further, quantitative analysis should be considered to find the absolute values to evaluate the measure.
Estimation of Cumulative Output Energy of Oscillating Water Column Wave Energy Converter Considering Power Take Off Damping
Authors: Iino Mitsumasa , Miyazaki Takeaki , Iida Makoto
Published: December 2020

The objective of this study is to investigate the influence of damping from the PTO device on the cumulative output of the oscillating water column wave energy converter under real sea conditions which encompasses wide range of wave period and height. In this presentation, a time domain dynamic simulation model of OWC motion is developed and validated with water tank test results. Then the model is used to calculate a wide range of wave period and height. Finally, annual cumulative air power output of OWC is calculated with different damping values.

In the water tank experiment, a cylindrical oscillating water column with a diameter of 0.3 m and submerged depth of 0.2 m is tested. PTO damping was emulated by using several orifice plates. Since the orifice pressure is proportional to square of flow-rate of the orifice, In the simulation, a model was constructed to solve the dynamic equation of motion assuming water column as a rigid equivalent floating body. Validation showed the model captures the influence of PTO damping as observed in the water tank testing. Using simulation, output air power from real scale OWC was evaluated under wide range of inlet wave period and height. With the output power database from dynamic simulation and frequency of wave height and period at specific sites in Japan (Fukui and Kamaishi), annual cumulative output power is calculated.

From the results, it was confirmed that a higher output can be obtained with higher energy in high waves by adopting a damping characteristic that increases the efficiency under a wide wave condition rather than a nozzle characteristic that achieves maximum efficiency in the resonance period. Furthermore, it became clear that the damping that increases the maximum efficiency does not necessarily increase the accumulated energy. When considering operation in real sea condition in the future, it is not always effective to select PTO damping that maximizes the output at specific wave height or period. And it is important to adopt a method that can estimate wide range of wave condition and evaluate the cumulative output power.
Statistical Determination of Bit-Rock Interaction and Drill String Mechanics for Automatic Drilling Optimization
Authors: Ambrus Adrian , Daireaux Benoît , Carlsen Liv A. , Mihai Rodica G. , Karimi Balov Mohsen , Bergerud Ronny
Published: December 2020

The ability to predict the response of a drill bit to the topside axial and rotational velocities of the drill-string is a prerequisite for any system aimed at automatically controlling the drilling parameters to optimize the rate of penetration and the overall quality of the well construction process. When drilling with a Polycrystalline Diamond Compact (PDC) bit, even the steady-state response can exhibit complex behavior, characterized by the presence of (at least) three different regimes whose range and parameters depend upon the bit characteristics and the mechanical properties of the formations being drilled. Transient effects significantly complicate the situation, especially when vibrations (axial, rotational or lateral) disturb the drilling process. Often, the root cause of these vibrations lies in the bit-rock interaction itself, while the drill string, through its elasticity and interaction with the borehole wall, may amplify or attenuate these vibrations. Therefore, continuous calibration of the drill string and bit-rock parameters from available surface and downhole measurements is critical for any automated control system relying on dynamic models of the drilling process.

We present a calibration procedure whose goal is two-fold: first, to identify the time-varying parameters involved in the bit-rock interaction, and second, to provide a low-order, transfer function model approximation of the drill string axial and rotational dynamics. Our approach is based on particle filter techniques and a refined instrumental variable method for transfer function model estimation, and allows for real-time estimation of the various model parameters. We illustrate its behavior against recorded drilling data, where the proposed methods are shown to capture the different dynamics in place. We explain, in addition, how the calibrated drill string and bit-rock interaction models can be integrated in a framework to identify drilling parameter regions prone to axial or rotational vibrations.
Collapse Analysis of Ship Hull Girder Using Hydro-Elastoplastic Beam Model: Part 2
Authors: Ko Han Htoo Htoo , Tatsumi Akira , Iijima Kazuhiro , Fujikubo Masahiko
Published: December 2020

In Part 1 study, a time-domain collapse analysis method of ship hull girder was developed and named FE-Smith method. Hull girder was treated as elastoplastic beam model and Smith’s method was used for collapse analysis of cross sections. A concept of average stress-average plastic strain relationship was introduced so that nonlinear collapse behavior of members can be treated as pseudo strain-hardening/softening behavior. Fluid-structure interaction effects were considered. Uniform cross-section beam was assumed as a most fundamental study.

In this Part 2, a container ship is taken as subject model. Not only FE-Smith analysis but also non-linear FE analyses using shell model for collapse parts are performed for comparison purpose. Two types of average stress-average strain curves are considered for FE-Smith analysis, i.e. obtained by Gordo-Soares formulae and by shell FEM. Applicability of FE-Smith method is examined comparing with more precise but time-consuming methods. Some parametric studies are also performed. Wave response will be reported in the next papers.
Subsea HIPPS Monetary Value: Perception and Reality
Authors: Priyadarshi Hemant , Harrold David , Baig Arif , Tagore Anupam
Published: December 2020

In a subsea production environment, a HIPPS (High Integrity Pressure Protection System) is used to operate the system at a design pressure lower than the Shut-in tubing pressure. It helps maintain high reliability against overpressure or burst scenarios. This paper introduces a subsea HIPPS system and its application principle. It also discusses how HIPPS can be an enabler for developing high pressure remote or stranded fields.

Furthermore, it discusses the perceived hardware/project cost reduction benefits, which may or may not be available or are insignificant. From experience on multiple field development projects, HIPPS is an enabler for connecting differently rated systems; however, monetary savings are not a given and vary from field to field. Attention must be given to total installed costs of the system before associating monetary gains with the introduction of HIPPS. The content and scenarios presented in this paper pertain to deep-water field developments.
Development of a Numerical Dynamic Mooring Model for Visco-Elastic and Visco-Plastic Deformation of Synthetic Ropes
Authors: Nguyen Nhu , Sharman Krish Thiagarajan
Published: December 2020

Synthetic ropes are increasingly being considered for various offshore and marine applications, including for mooring offshore wind turbines and for aquaculture cages. Studies have shown that nonlinear behaviors of a synthetic rope in a dynamic environment can complicate the mooring system analysis. Nonlinear stiffness coupled with time- and load history-dependent characteristics of fibrous materials can allow for over or under estimation of the mooring forces. It is critical that these nonlinear properties are incorporated correctly into a mooring model, especially for studies of structures’ performances in extreme events. The study aims at developing a simulation tool capable of predicting the dynamic behavior of highly extensible synthetic mooring system used in coastal and offshore floating structures. The program employs an implicit finite-difference approach to model the dynamic behaviors of the mooring line subjected to user-defined motions of the fairlead. As opposed to a linear stress-strain relationship typically incorporated in other mooring models, the current program is built with constitutive model of fibrous materials to account for the nonlinearity time- and load-dependent characteristics of synthetic lines. As part of the program, an inverted constitutive stress-strain model, in which stresses are calculated from given strains in stress-based formulas, were presented. Comparisons with published data indicates that the proposed inverted nonlinear stress-strain formulas were successfully integrated with the mooring solver. The coupled nonlinear mooring program predicts accurately both nonlinear reversible and irreversible deformations of synthetic cables.
Comparison of the CFD Results to PIV Measurements in Kinematics of Spilling and Plunging Breakers
Authors: Düz Bülent , Scharnke Jule , Hallmann Rink , Tukker Jan , Khurana Siddhant , Blanchard Kevin
Published: December 2020

The kinematics under spilling and plunging breakers are investigated using both experimental and numerical methods. In a modular laboratory flume, the breakers were generated using dispersive focusing, and the kinematics underneath them were measured utilizing the Particle Image Velocimetry (PIV) technique. Using the state-of-art high-speed video cameras and lasers, the kinematics were measured at a high sampling rate without needing phase-locked averaging. Afterwards, Computational Fluid Dynamics (CFD) simulations were carried out for comparison purposes. These simulations were run in single-phase using a finite-volume based Navier-Stokes solver with a piecewise-linear interface reconstruction scheme. The spilling and plunging breakers from the measurements were reconstructed in the computational domain using an iterative scheme. As a result a good match with the measured waves was obtained in the simulations. Results indicate that even though measured kinematics are somewhat higher than the simulated ones especially in the spilling and overturning regions, the CFD simulations can accurately capture the relevant details of the flow and produce reasonably accurate kinematics in comparison with the PIV results.
Hydrodynamic Analysis of Macroalgae Local Model Using Computational Fluid Dynamics
Authors: Chen Ming , Yim Solomon C. , Cox Daniel , Yang Zhaoqing , Mumford Thomas
Published: December 2020

In this article, a local scale, fully nonlinear coupled fluid-structural interaction (FSI) sugar kelp model has been developed using a computational fluid dynamics (CFD) method. In this model, to be consistent with available experimental data, the sugar kelp is approximated as elongated rectangles with smoothed isosceles triangles at the ends and a single kelp model with one end fixed in a channel with constant current model is developed. Several different current speeds are simulated, and the resulting drag forces and calculated drag coefficients are validated by comparison with experimental data from the literature. In a previous study, a global scale model was developed using a computational structural dynamics (CSD) method to simulate macroalgae farming system and guide the system configuration design. In the global scale model, the hydrodynamic forces are calculated using Morison’s equation and the kinematics and dynamics of the sugar kelp are simplified and the group of kelps attached to the long line is modeled as a slender structure with the same length and an effective diameter such that the volumes are consistent with the real physical system. This simplified model matches the weight and buoyancy but adjusting the hydrodynamic properties when the general hydrodynamic coefficients are employed. Therefore, optimal hydrodynamic coefficients used in global scale model were determined to obtain the hydrodynamic force more accurately. The validated local scale model is then be applied to determine the hydrodynamic coefficients of the simplified sugar kelp model for global dynamic analysis.
Centrifuge Model Tests on Effects of Spudcan Penetration on Adjacent Loaded Piles
Authors: Wang Jianhua , Fan Yifei
Published: December 2020

It is very important for designers of offshore platforms to understand affecting mechanism of mobile jack-up spudcan penetration and extraction on adjacent loaded piles. Existing centrifuge model tests are on effects of spudcan penetration on adjacent unloaded piles. In engineering, offshore platform piles are subjected to lateral and vertical pile head loads before spudcan penetration. In order to understand affecting mechanism of spudcan penetration on adjacent loaded piles, centrifuge model tests were conducted under 50g condition. Model test strata are the saturated soft clay and the fine sand and the model pile head constraint is free. Spudcan penetration resistances, lateral earth pressures along pile shaft, lateral pile deflection, vertical pile displacement, bending moments and axial forces along pile shaft are measured during spudcan penetration and after extraction. Effects of spudcan penetration on the pile-soil interaction p-y relationship and the bearing capacity of piles are analyzed based on model test results. Results show that the lateral soil resistance affected by spudcan penetration decreases due to soil movement. The lateral deflection of loaded pile obviously increases, the side frictional resistance decreases and the end resistance increases during spudcan penetration. The spudcan penetration-induced incremental pile response does not disappear after spudcan extraction. These results are helpful for understanding the effect mechanism of spudcan penetration and extraction on adjacent loaded piles.
Numerical Modeling of Turbulent Wall-Bounded Oscillatory Flow and its Effect on Small-Diameter Pipelines
Authors: Jiang Hongyi , Cheng Liang
Published: December 2020

This study investigates the effect of wave-induced boundary layer on the on-bottom stability of small-diameter pipelines laid on the seabed. An ω-based wall boundary condition is adopted, owing to its high mesh resolution down to the viscous sublayer to resolve the flow around the pipeline. By taking into account the wave boundary layer, the present numerical simulations predict required specific gravity for small-diameter pipelines close to the theoretical estimation by Cheng et al. (2016) and, as expected, much smaller than those recommended by DNV-RP-F109.
Roll Damping Simulations of an Offshore Heavy Lift DP3 Installation Vessel Using the CFD Toolbox OpenFOAM
Authors: Devolder Brecht , Stempinski Florian , Mol Arjan , Rauwoens Pieter
Published: December 2020

In this work, the roll damping behavior of the offshore heavy lift DP3 installation vessel Orion from the DEME group is studied. Boundary element codes using potential flow theory require a roll damping coefficient to account for viscous effects. In this work, the roll damping coefficient is calculated using the Computational Fluid Dynamics (CFD) toolbox OpenFOAM. The two-phase Navier-Stokes fluid solver is coupled with a motion solver using a partitioned fluid-structure interaction algorithm. The roll damping is assessed by the Harmonic Excited Roll Motion (HERM) technique. An oscillating external moment is applied on the hull and the roll motion is tracked. Various amplitudes and frequencies of the external moment and different forward speeds, are numerically simulated. These high-fidelity full-scale simulations result in better estimations of roll damping coefficients for various conditions in order to enhance the accuracy of efficient boundary element codes for wave-current-structure interactions simulations.
Dynamic Response of Jacket-Support Offshore Wind Turbine Under Ice Crushing Load
Authors: Chuang Zhenju , Li Chunzheng , Liu Shewen , Lu Yu
Published: December 2020

Offshore wind is one of the fastest developing renewable energy in the world. With increasing exploratory activities in the polar area, wind energy in the cold climate attracts more and more attention. This paper presents an integrated analysis of the ice-structure interaction of a jacket-type offshore wind turbine (OWT). An aero-hydro-servo-elastic jacket wind turbine is created in FAST, which is a well-known tool for wind turbine simulation. Due to vertically sided jacket legs, crushing ice-structure interaction modes are calculated based on the methodology suggested by ISO 19906. Time-domain calculations are carried out for random crushing, intermittent crushing and lock-in crushing between the bottom fixed wind turbine and moving ice feature. Influential parameters like ice thickness, ice strength, ice moving direction and velocity are all studied in this paper. Results show that the ice load has a significant impact on the structure response. The more ice thickness and ice strength will induce the higher structure response mean level, as well as the oscillation amplitudes in all the investigated crushing modes.
MoorDyn V2: New Capabilities in Mooring System Components and Load Cases
Authors: Hall Matthew
Published: December 2020

MoorDyn, an open-source mooring dynamics model, is being expanded with capabilities for additional mooring system features and load cases. As floating wind turbine technology matures, mooring systems are becoming more sophisticated and more complex scenarios need to be considered in the design process. Mooring systems may have synthetic line materials, ballast/buoyancy bodies along the lines, or interconnections between platforms. Failure modes may involve multiple cascading line failures that depend on mooring system dynamics.

Features recently added to MoorDyn aim to address these emerging needs. MoorDyn’s linear elasticity model has been supplemented to support user-defined stress-strain curves, which can be adjusted to represent synthetic mooring materials. Rigid six-degree-of-freedom bodies in the mooring system can now be modeled using two new model objects. “Rod” objects provide an option for rigid cylindrical bodies. They use the existing Morison equation-based hydrodynamics model and can be connected to mooring lines at either end. “Body” objects provide a generic six-degree-of-freedom rigid-body representation based on a lumped-parameter model of translational and rotational properties. Rod objects can be added to Body objects and mooring lines can be attached at any location, allowing a wide variety of submerged structures to be integrated into the mooring system. Lastly, a means of dynamically simulating mooring line failures has been implemented.

These new features, currently in the C++ version of MoorDyn, are described and then demonstrated on a two-turbine shared-mooring array. A qualitative view of the results suggests the new features are functioning as expected.
Growth during the first summer at sea modulates sex-specific maturation schedule in Atlantic salmon
Authors: Tréhin Cécile , Rivot Etienne , Lamireau Ludivine , Meslier Lisa , Besnard Anne-Laure , Gregory Stephen D. , Nevoux Marie
Published: December 2020

Recent decline in abundance of Atlantic salmon (Salmo salar) and concomitant changes in life history may result from a decline in the growth conditions during marine migration. Available literature suggests the existence of a sex-specific reaction norm linking maturation with environmental growth conditions at sea. However, the extent to which this mechanism explains variations in age at maturity remains unclear. Using a historical collection of scales (1987–2017) from the Sélune River, France, we showed that marine growth declined over the first summer and remained stable during the subsequent periods at sea among returning salmon. Results support the hypothesis of a sex-specific probabilistic reaction norm, with individual probability to return after 1 year at sea increasing when growth increases. Females may require higher growth than males to attain their maturation threshold. This mechanism is a good candidate to explain temporal variability in sea-age at return at both the individual and population level in the Sélune population and in many other southern European populations.
Importance of sample size for estimating prevalence: a case example of infectious hematopoietic necrosis viral RNA detection in mixed-stock Fraser River sockeye salmon (Oncorhynchus nerka), British Columbia, Canada
Authors: Laurin Emilie , Bradshaw Julia , Hawley Laura , Gardner Ian A. , Garver Kyle , Johnson Stewart C. , Thakur Krishna K.
Published: December 2020

Proper sample size must be considered when designing infectious-agent prevalence studies for mixed-stock fisheries, because bias and uncertainty complicate interpretation of apparent (test)-prevalence estimates. Sample size varies between stocks and are often smaller than expected during wild-salmonid surveys. Our case example of 2010–2016 survey of sockeye salmon (Oncorhynchus nerka) from different stocks of origin in British Columbia, Canada, illustrated the effect of sample size on apparent-prevalence interpretation. Molecular testing (viral RNA RT-qPCR) for infectious hematopoietic necrosis virus (IHNv) revealed large differences in apparent prevalence across wild salmon stocks (much higher from Chilko Lake) and sampling location (fresh water or marine), indicating differences in both stock and host life-stage effects. Ten of the 13 marine non-Chilko stock–years with IHNv-positive results had small sample sizes (<30 samples per stock–year), which, with imperfect diagnostic tests (particularly lower diagnostic sensitivity), could lead to inaccurate apparent-prevalence estimation. When calculating sample size for expected apparent prevalence using different approaches, smaller sample sizes often led to decreased confidence in apparent-prevalence results and decreased power to detect a true difference from a reference value.
Searching for lepton flavor violating decays $$\tau \rightarrow Pl$$ in the minimal R-symmetric supersymmetric standard model
Authors: Sun Ke-Sheng , Guo Tao , Li Wei , Yang Xiu-Yi , Zhao Shu-Min
Published: December 2020

We analyze the lepton flavor violating decays $$\tau \rightarrow Pl$$

τ
→
P
l

($$P=\pi ,\eta ,\eta ';\;l=e,\mu $$

P
=
π
,
η
,

η
′

;

l
=
e
,
μ

) in the scenario of the minimal R-symmetric supersymmetric standard model. The prediction on the branching ratios BR$$(\tau \rightarrow P e)$$

(
τ
→
P
e
)

and BR$$(\tau \rightarrow P \mu )$$

(
τ
→
P
μ
)

is affected by the mass insertion parameters $$\delta ^{13}$$

δ
13

and $$\delta ^{23}$$

δ
23

, respectively. These parameters are constrained by the experimental bounds on the branching ratios BR($$\tau \rightarrow e (\mu ) \gamma $$

τ
→
e
(
μ
)
γ

) and BR($$\tau \rightarrow 3e(\mu )$$

τ
→
3
e
(
μ
)

). The result shows Z penguin dominates the prediction on BR($$\tau \rightarrow Pl$$

τ
→
P
l

) in a large region of the parameter space. The branching ratios for BR($$\tau \rightarrow Pl$$

τ
→
P
l

) are predicted to be, at least, five orders of magnitude smaller than present experimental bounds and three orders of magnitude smaller than future experimental sensitivities.
Evaluation of CCD cameras for beam profile monitoring with high intensity particle beams traversing gases
Authors: Hampf Raphael , Ulrich Andreas , Wieser Jochen
Published: December 2020

Measurements of the absolute sensitivity of three different optical cameras are presented. An absolutely calibrated tungsten strip-lamp was used for calibrating the devices. An experimental method for determining the solid angle which is accepted by the combination of the cameras with a broadband apochromatic lens is described. The results with five bandpass filters between 337nm and 740nm are shown. The signal to noise ratio and the spatial resolution of the camera systems is also discussed.
The Fourier–Mukai transform of a universal family of stable vector bundles
Authors: Reede Fabian
Published: December 2020

In this note we prove that the Fourier–Mukai transform [Formula: see text] of the universal family of the moduli space [Formula: see text] is not fully faithful.
The spin-one DKP equation with a nonminimal vector interaction in the presence of minimal uncertainty in momentum
Authors: Hamil B. , Lütfüoğlu B. C. , Aounallah H.
Published: December 2020

In this work, we consider the relativistic Duffin–Kemmer–Petiau equation for spin-one particles with a nonminimal vector interaction in the presence of minimal uncertainty in momentum. By using the position space representation, we exactly determine the bound-states spectrum and the corresponding eigenfunctions. We discuss the effects of the deformation and nonminimal vector coupling parameters on the energy spectrum analytically and numerically.
Optical properties of He+-implanted fused silica glass waveguides
Authors: You Jia-Li , Lin Shuo-Qi , Zhang Jie , Lin She-Bao , Fu Li-Li , Zheng Rui-Lin , Zhang Liao-Lin , Liu Chun-Xiao
Published: December 2020

An optical waveguide is an important dielectric device that guides the propagation of light waves. Ion implantation is a competitive waveguide preparation technique with advantages including reliance, simpleness and flexibility. In this work, a 400-keV helium ion implantation with a fluence of [Formula: see text] ions/cm2 was carried out to manufacture a planar waveguide on the surface of the fused silica glass. The formation mechanism of the waveguide was analyzed by the nuclear energy deposition based on the SRIM 2013 and the refractive index distribution with the help of the reflectivity calculation method (RCM). The geometry structure and the guiding performance of the waveguide were studied by the metallographic microscope and the end-face coupling system, respectively. The investigation on the fabrication and characteristics of fused silica glass optical waveguides is of great significance for the development of passive devices in the field of optical communications.
Developing Covariational Reasoning Among Students Using Contexts of Formulas
Authors: Sokolowski Andrzej
Published: December 2020

Multiple studies have been conducted to assess students’ ability to apply covariational reasoning to sketching graphs in physics. This study is supported by research on developing students’ skills in sketching functions in mathematics. It attempts to evaluate physics students’ ability to apply these skills to identify critical algebraic attributes of physics formulas for their potential to be sketched. Rather than seeking formulas’ physical interpretation, this study is posited to challenge students’ skills to merge their mathematical knowledge within physics structures. A group of thirty ([Formula: see text]) first-year college-level physics students were provided with two physically identical equations that described the object’s position. However, one equation was expressed in functional mathematical notation, whereas the other in a standard formula notation. The students were asked to classify the symbols in each formula as variables or parameters and determine these formulas’ potential to be graphed in respective coordinates. The analysis revealed that 93% of these students considered function notation as possessing sketchable potential against 13% who envisioned such potential in the standard formula notation. Further investigations demystified students’ confusion about the classification of the symbols used in the formula notation. These results opened up a gate for discussing the effects of algebraic notations in physics on activating students’ covariational skills gained in mathematics courses. Suggestions for improving physics instructions stemming from this study are discussed.
Genetic Advancement and Variability of Released Common Bean (Phaseolus vulgaris L.) Varieties from 1974–2009 GC in Ethiopia
Authors: Kefelegn Nigussie , Mekibib Frew , Dessalegn Yigzaw
Published: December 2020

The efficiency of variety development can be determined with variability and genetic progress of released varieties. The aim of this study was to determine the variability and genetic advancement of common bean varieties. Randomized Completed Block Design was used to evaluate 15 varieties at Koga and Chefa in 2013. Cluster, principal, and biplot analysis including genetic parameter estimation were done following analysis of variance. Significant variation was observed among the varieties, and they are clustered into four groups. Seed color and size were found as an important factors for clustering of the varieties. Hawassa Dume and Nasir have red and small seeded, respectively, and clustered in one group. Similarly, Awash 1 and Awash Melka are both small white and clustered in one group. Hawassa Dume was highly similar to Nasir, and Red Wolayta with Dimitu, while a large distance was recorded between Awash Melka and Haramaya. Deme and Haramaya were found the most divergent and unique among the tested varieties. This is also reflected in biplot drown by principal components 1 and 2, which together accounted for about 82.022. Plant heights, seed weight, days to maturity, and harvest index have the largest contribution to the total variation of the varieties. Most of the traits have a high phenotypic and genotypic coefficient of variation, heritability, and genetic advance, and selection was effective in the breeding program. The breeding program has brought about 0.27 tonnes of seed yield increment or an annual rate of genetic progress of 0.0077 t ha−1 (0.37% ha−1 year−1). However, the breeding program should reconsider the breeding procedure as there are some varieties released in the same year with similar genetic potential.
Magnesium Sulfate Attenuates Lethality and Oxidative Damage Induced by Different Models of Hypoxia in Mice
Authors: Mohammadi Hamidreza , Shamshirian Amir , Eslami Shafagh , Shamshirian Danial , Ebrahimzadeh Mohammad Ali
Published: December 2020

Mg2+ is an important cation in our body. It is an essential cofactor for many enzymes. Despite many works, nothing is known about the protective effects of MgSO4 against hypoxia‐induced lethality and oxidative damage in brain mitochondria. In this study, antihypoxic and antioxidative activities of MgSO4 were evaluated by three experimental models of induced hypoxia (asphyctic, haemic, and circulatory) in mice. Mitochondria protective effects of MgSO4 were evaluated in mouse brain after induction of different models of hypoxia. Antihypoxic activity was especially pronounced in asphyctic hypoxia, where MgSO4 at dose 600 mg/kg showed the same activity as phenytoin, which used as a positive control (P < 0.001). In the haemic model, MgSO4 at all used doses significantly prolonged latency of death. In circulatory hypoxia, MgSO4 (600 mg/kg) doubles the survival time. MgSO4 significantly decreased lipid peroxidation and protein carbonyl and improved mitochondrial function and glutathione content in brain mitochondria compared to the control groups. The results obtained in this study showed that MgSO4 administration has protective effects against lethality induced by different models of hypoxia and improves brain mitochondria oxidative damage.
Biomechanical Consequences of Nail Insertion Point and Anterior Cortical Perforation for Antegrade Femoral Nailing
Authors: Ching Michael , Gee Aaron , Del Balso Christopher , Lawendy Abdel , Schemitsch Emil H. , Zdero Radovan , Sanders David
Published: December 2020

This biomechanical study assessed the influence of changing antegrade cephalomedullary nail insertion point from anterior to neutral to posterior locations relative to the tip of the greater trochanter with or without anterior cortical perforation in the distal femur. Artificial osteoporotic femurs and cephalomedullary nails were used to create 5 test groups each with 8 specimens: intact femur without a nail or perforation, anterior nail insertion point without perforation, neutral nail insertion point without perforation, posterior nail insertion point without perforation, and posterior nail insertion point with perforation. Nondestructive biomechanical tests were done at 250 N in axial, coronal 3‐point bending, sagittal 3‐point bending, and torsional loading in order to measure overall stiffness and bone stress. The intact femur group vs. all femur/nail groups had lower stiffness in all loading modes (p ≤ 0.018), as well as higher bone stress in the proximal femur (p ≤ 0.027) but not in the distal femur above the perforation (p = 0.096). Compared to each other, femur/nail groups only showed differences in sagittal 3‐point bending stiffness for anterior and neutral vs. posterior nail insertion points without (p ≤ 0.025) and with perforation (p ≤ 0.047). Although it did not achieve statistical significance (p ≥ 0.096), moving the nail insertion point from anterior to neutral to posterior to posterior with perforation did gradually increase bone stress by 45% (proximal femur) and 46% (distal femur). No femur or hardware failures occurred. Moving the nail insertion point and the presence of a perforation had little effect on stiffness, but the increased bone stress may be important as a predictor of fracture. Based on current bone stress results, surgeons should use anterior or neutral nail insertion points to reduce the risk of anterior cortical perforation.
Research on Operation Characteristics and Safety Risk Forecast of Bus Driven by Multisource Forewarning Data
Authors: Deng Shejun , Yu Hongru , Lu Caoye
Published: December 2020

To prevent and control public transport safety accidents in advance and guide the safety management and decision-making optimization of public transport vehicles, based on the forewarning and other multisource data of public transport vehicles in Zhenjiang, holographic portraits of public transport safety operation characteristics are constructed from the perspectives of time, space, and driver factors, and a prediction model of fatigue driving and driving risk of bus drivers based on BP neural network is constructed. Finally, model checking and virtual simulation experiments are carried out. The result of the research shows that the driver’s fatigue risk during the period of 7 : 00-8 : 00 am is much higher than other periods. When the bus speed is about 30 km/h, the driver fatigue forewarning events occur the most. Drivers aged 30–34 years have the largest proportion of vehicle abnormal forewarning, drivers aged 40–44 years have the largest proportion of fatigue forewarning events, and drivers with a driving experience of 15–19 years have the largest overall proportion of various forewarning events. When the vehicle speed range is (18, 20) km/h and (42, 45) km/h, the probability of fatigue driving risk and driving risk forewarning increases sharply; and when the vehicle speed is lower than 17 km/h or 41 km/h, the probability of fatigue driving risk and driving risk forewarning, respectively, is almost zero. The probability of fatigue forewarning during low peak hours on rainy days is about 30% lower than that during peak hours. The probability of driving forewarning during flat peak hours is 15% higher than that during low peak hours and about 10% lower than that during peak hours. This paper realized for the first time the use of real forewarning data of buses in the full time, the whole region, and full cycle to carry out research. Related results have important theoretical value and practical significance for scientifically guiding the safety operation and emergency management strategies of buses, improving the service level of bus passenger transportation capacity and safety operation, and promoting the safety, health, and sustainable development of the public transportation industry.
Nomogram to Predict Poor Outcome after Mechanical Thrombectomy at Older Age and Histological Analysis of Thrombus Composition
Authors: Meng Longyan , Wang Haichao , Yang Hua , Zhang Xiang , Zhang Quanbin , Dong Qiong , Shu Zhongwen , Chen Liuwei , Gong Li , Zhao Yanxin
Published: December 2020

An easy scoring system to predict the risk of poor outcome after mechanical thrombectomy among the elderly is currently not available. Therefore, we aimed to develop a nomogram for predicting the probability of negative prognosis in aged patients with acute ischemic stroke undergoing thrombectomy. In addition, we sought to investigate the association between histological thrombus composition and stroke characteristics. To this end, we prospectively studied a developed cohort using data collected from a stroke center from November 2015 to December 2019. The main outcome was functional independence, defined as a modified

Rankin
 
Scale
 
score
≤
2

at 90 days following a mechanical thrombectomy. A nomogram model based on multivariate logistic models was generated. The retrieved thrombi were stained with hematoxylin and eosin and assessed according to histological composition. Our results demonstrated that

age
≥
72
 
years

was independently associated with poor outcome. A total of 304 participants completed the follow-up data to generate the nomogram model. After multivariate logistic regression, five variables remained independent predictors of outcome, including older age, hemorrhagic transformation, thrombolysis in cerebral infarction score, National Institute of Health Stroke score, and neutrophil-to-lymphocyte ratio, and were used to generate the nomogram. The area under the receiver-operating characteristic curve of the model was 0.803. The clots from elderly subjects with large-artery atherosclerosis, anterior circulation, and successful recanalization groups had a higher percentage of fibrin compared to those of younger patients. This is the first nomogram to be developed and validated in a stroke center cohort for individualized prediction of poor outcome in elderly patients after mechanical thrombectomy. Clot composition provides valuable information on the underlying pathogenesis of oxidation in older patients.