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Investigation on structural component behaviours of double bottom arrangement under grounding accidents

Aditya Rio Prabowo, Teguh Muttaqie, Jung Min Sohn, Bangun I.R. Harsritanto

Accepted Manuscript , doi: 10.1016/j.taml.2019.01.010

[Abstract] (0) [FullText HTML] (0) [PDF 3626KB] (0)

Abstract:
Marine accidents have caused immense casualties on various parties in shipping and shipbuilding industries, including financial and structural losses. This situation makes ship accident becomes a critical subject in naval architecture and marine structures, as it needs continuous assessment and investigation to broaden insight and data of collision and grounding phenomena. The paper aims to investigate structural conditions of a ship arranged by double hull system under accidental scenario, namely ship grounding. Fundamental concept of structure-rock interaction in powered-hard grounding is adopted to design impact configuration for calculation using finite element (FE) simulation. Involved entities are defined as the structure represented by tanker vessel, and oceanic rock is deployed as the indenter in analysis. Calculation results indicate that the crashworthiness capability of structural part strengthened by longitudinal girder is higher than other selected locations on the structures against rock penetration. Localized flooding of storage oil may occur during raking damage is formed on structural part between two girders.

Key structure in laminar-turbulent transition of boundary layer with streaky structures

Joe Yoshikawa, Yu Nishio, Seiichiro Izawa, Yu Fukunishi

Corrected proof , doi: 10.1016/j.taml.2019.01.005

[Abstract] (25) [FullText HTML] (16) [PDF 2708KB] (4)

Abstract:
A numerical simulation is performed to find out a key vortical structure in the laminar-turbulent transition. A low-speed streak is generated inside a laminar boundary layer using an isolated cuboid roughness, aimed at providing an environment unstable to outer disturbances. Then, a short duration jet is issued into the boundary layer. When the jet velocity is low, some vortices appear in the boundary layer, but the transition of the boundary layer does not take place. However, when the jet velocity exceeds a certain threshold, two vortices newly appear above the elongated legs of a V-shaped vortex and only one of them is stretched and survives. After that, vortices are generated one after another around the survived one. By comparing the decayed and the survived vortices, it is found that the difference in their heights is the key characteristic which leads to the transition.

Seepage-stress coupled modeling for rainfall induced loess landslide

Danyang Zhou, Zhen Zhang, Jiachun Li, Xiaoliang Wang

Corrected proof , doi: 10.1016/j.taml.2019.02.006

[Abstract] (0) [FullText HTML] (0) [PDF 2843KB] (0)

Abstract:
Although rainfall is rare on the Loess Plateau of western China, landslides occur frequently there in rainy season. Surveys report that landslide hazards always follow heavy rains. In this study, a seepage-stress coupling model for rainfall induced landslide is used to examine an actual disastrous event in Yulin by the end of July, 2017. The effects of rainfall duration, rainfall intensity and soil weakening on slope stability are studied in detail. The results illustrate that the safety factor drops sharply at first and then is gradually declining to below 1.05 during additional two days of heavy rain. With soil strength softening considered, the slope would be more unstable, in which the weakening in soil cohesion is found to be a more sensitive factor.

Electrokinetic flow in the U-shaped micro-nanochannels

Bilong Qiu, Lingyan Gong, Zirui Li, Jongyoon Han

Corrected proof , doi: 10.1016/j.taml.2019.01.006

[Abstract] (6) [FullText HTML] (6) [PDF 2923KB] (0)

Abstract:
U-shaped micro-nanochannels can generate significant flow disturbance as well as locally amplified electric field, which gives itself potential to be microfluidic mixers, electrokinetic pumps, and even cell lysis process. Numerical simulation is utilized in this work to study the hidden characteristics of the U-shaped micro-nanochannel system, and the effects of key controlling parameters (the external voltage and pressure) on the device output metrics (current, maximum values of electric field, shear stress and flow velocity) were evaluated. A large portion of current flowing through the whole system goes through the nanochannels, rather than the middle part of the microchannel, with its value increasing linearly with the increase of voltage. Due to the local ion depletion near micro-nanofluidic junction, significantly enhanced electric field (as much as 15 fold at V=1 V and P₀=0) as well as strong shear stress (leading to electrokinetic flow) is generated. With increasing external pressure, both electric field and shear stress can be increased initially (due to shortening of depletion region length), but are suppressed eventually at higher pressure due to the destruction of ion depletion layer. Insights gained from this study could be useful for designing nonlinear electrokinetic pumps and other systems.

Dependency of gamma oscillations in E/I neuronal network on illumination contrast of external stimulus

Xiaochun Gu, Fang Han, Zhijie Wang, Xia Peng

Corrected proof , doi: 10.1016/j.taml.2019.01.001

[Abstract] (11) [FullText HTML] (7) [PDF 3048KB] (1)

Abstract:
Synchronous gamma oscillations are believed to play a prominent role in the information processing of biological neural systems. Experimental observations have found that the frequency and power of gamma oscillations in the primary visual cortex (V1 zone) are regulated by the illumination contrast of visual stimulus. However, the underlying mechanism of how the synchronous oscillations depend on the illumination contrast has not been well explained. We propose a local excitatory/inhibitory (E/I) neuronal network of integrate-and-fire (IAF) neurons with the difference-of-Gaussians (DOG) receptive field to unveil this mechanism. Simulation results demonstrate that the higher the illumination contrast, the higher the frequency of gamma oscillations. The power of gamma oscillations also increases with the increase of illumination contrast. These results are consistent with the experimental findings.

An energy approach to predict electromigration induced grain rotation under high current density

Yuexing Wang, Yao Yao

Corrected proof , doi: 10.1016/j.taml.2019.01.002

[Abstract] (22) [FullText HTML] (22) [PDF 2643KB] (1)

Abstract:
An energy approach is proposed to describe the electromigration induced grain rotation under high current density. The driving force is assumed to arise from the grain-boundary energy reduction and increase of the inner energy from the joule heating. Energy dissipates by the grain boundary diffusion under electromigration and viscous boundary sliding is considered. Based on the conservation of energy production and dissipation, an equilibrium equation is developed to predict the grain rotation rate analytically. It is recognized that the grain rotates with the reducing of electrical resistivity and inversely proportional to the grain length. The theoretical prediction is compared with the experimental data, which shows good accuracy on the rotation trend and the specific rotation rate.

The extractable hydrokinetic power from an oscillating membrane-based harvester

Francisco J. Arias

Accepted Manuscript , doi: 10.1016/j.taml.2019.01.003

[Abstract] (0) [FullText HTML] (0) [PDF 2579KB] (0)

Abstract:
The extractable hydrokinetic power from an oscillating membrane in standing motion and induced by a water flow and its possible significance with regard energy harvesting is discussed. The main attractiveness of such an energy harvester lies in the possibility of an inexpensive technology able to be used in those water flows which either because limitation of space (narrow channels) or a limited differential pressure drop with the surrounding but yet with a non negligible velocity are not well suited to be turbined. Utilizing a simplified geometrical model, an estimate of the extractable output density power per area of membrane was derived. Preliminary experiments were performed using a rectangular thin rubber membrane and for a typical domestic water intake as source. The experimental data quantitatively agree very well with the theoretical prediction where it was found that for water flows around 2m/s the output power density from the membrane may be around 30 mW/cm² of membrane. Additional R&D is required in order to arrive at a reliable practical and commercial design.

Lattice Boltzmann model of percutaneous drug absorption

Arman Safdari, Kyung Chun Kim

Accepted Manuscript , doi: 10.1016/j.taml.2019.01.008

[Abstract] (0) [FullText HTML] (0) [PDF 2925KB] (0)

Abstract:
A lattice Boltzmann numerical modeling method was developed to predict skin concentration after topical application of a drug on the skin. The method is based on D2Q9 lattice spaces associated with the Bhatnagar-Gross-Krook (BGK) collision term to solve the convection-diffusion equation (CDE). A simulation was carried out in different ranges of the value of bound

\begin{document}$\gamma $\end{document}

, which is related to skin capillary clearance and the volume of diffusion during a percutaneous absorption process. When a typical drug is used on the skin, the value of

\begin{document}$\gamma $\end{document}

corresponds to the amount of drug absorbed by the blood and the absorption of the drug added to the skin. The effect of

\begin{document}$\gamma $\end{document}

was studied for when the region of skin contact is a line segment on the skin surface.

Effects of interfacial discontinuity on the fracture behavior in the superconductor-substrate system

Lang Jiang, Xiaoqiang Ren, Zhiwen Gao, Youhe Zhou

Accepted Manuscript , doi: 10.1016/j.taml.2019.01.009

[Abstract] (1) [FullText HTML] (0) [PDF 3220KB] (1)

Abstract:
This study concerns a two-dimensional model and the corresponding virtual crack closure technique (VCCT) implemented to solve the general boundary value problems that may explain why interface discontinuity has effects on the fracture behavior in the superconductor-substrate system. The interfacial discontinuity can be classified according to the material properties' continuity and their derivatives' continuity at the interface. For nonhomogeneous superconductor and substrate specimens with various material properties, a VCCT method is developed to calculate their fracture behavior. Furthermore, the effects of applied magnetic field amplitude and nonhomogeneous parameters are extensively and parametrically studied in two activation processes (zero-field cooling and field cooling). The integrative and computational study presented here provides a fundamental mechanistic understanding of the fracture mechanism in the superconductor-substrate system and sheds light on the rational design of interfacial continuity.

Optimal control of a mobile robot on sphere

Huageng Liu, Donghua Shi

Accepted Manuscript , doi: 10.1016/j.taml.2019.01.004

[Abstract] (5) [FullText HTML] (7) [PDF 2631KB] (0)

Abstract:
For the purpose of solving optimal control problem of a wall-crawling mobile robot working on spherical containers, we propose the Hamel's formalism for Pontryagin Maximum Principle, which gives a general framework for the optimal control of a mechanical system with velocity constraints, especially nonholonomic constraints. The effectiveness of the proposed framework is shown by the simulations for the above problem.

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Letter

Data-driven computing in elasticity via kernel regression

Yoshihiro Kanno

2018, 8(6): 361 -365. doi: 10.1016/j.taml.2018.06.004

[Abstract] (85) [FullText HTML] (53) [PDF 2626KB] (4)

Abstract:
This paper presents a simple nonparametric regression approach to data-driven computing in elasticity. We apply the kernel regression to the material data set, and formulate a system of nonlinear equations solved to obtain a static equilibrium state of an elastic structure. Preliminary numerical experiments illustrate that, compared with existing methods, the proposed method finds a reasonable solution even if data points distribute coarsely in a given material data set.

The effects of mean sea level rise and strengthened winds on extreme sea levels in the Baltic Sea

Magnus Hieronymus, Christian Dieterich, Helén Andersson, Robinson Hordoir

2018, 8(6): 366 -371. doi: 10.1016/j.taml.2018.06.008

[Abstract] (48) [FullText HTML] (27) [PDF 5040KB] (4)

Abstract:
Mean sea level rise and climatological wind speed changes occur as part of the ongoing climate change and future projections of both variables are still highly uncertain. Here the Baltic Sea's response in extreme sea levels to perturbations in mean sea level and wind speeds is investigated in a series of simulations with a newly developed storm surge model based on the nucleus for European modeling of the ocean (NEMO)-Nordic. A simple linear model with only two tunable parameters is found to capture the changes in the return levels extremely well. The response to mean sea level rise is linear and nearly spatially uniform, meaning that a mean sea level rise of 1 m increases the return levels by a equal amount everywhere. The response to wind speed perturbations is more complicated and return levels are found to increase more where they are already high. This behaviour is alarming as it suggests that already flooding prone regions like the Gulf of Finland will be disproportionally adversely affected in a future windier climate.

New interpretation of specific sign of Reynolds stress in the boundary layer on a flat plate

L.M. Lin, Y.X. Wu

2018, 8(6): 372 -377. doi: 10.1016/j.taml.2018.06.006

[Abstract] (97) [FullText HTML] (56) [PDF 2864KB] (15)

Abstract:
The specific sign of Reynolds stress in the boundary layer on a flat plate at zero incidence is newly interpreted in present paper based on the theory of vortex-induced vortex. It avoids some problems appeared in a traditional explanation, on the basis of relationship between mean and fluctuating flows due to the transport of momentum. Through the analysis of local flow field in the immediate neighborhood of wall, the characteristics of Reynolds stress are identified through introducing turbulence-induced small-scale streamwise eddies above the flat plate. The positive Reynolds stress is theoretically verified. And such new interpretation illustrates that the generation of Reynolds stress, as well as fluctuating velocity, is intrinsically independent of the mean flow. But its specific sign would be determined by the mean flow due to the inertial forces. Other features, such as the intensity relationship among three components of fluctuating velocity, are also presented.

An improved smoke-wire flow visualization technique using capacitor as power source

N. Gao, X.H. Liu

2018, 8(6): 378 -383. doi: 10.1016/j.taml.2018.06.010

[Abstract] (56) [FullText HTML] (33) [PDF 2900KB] (3)

Abstract:
An improved smoke-wire flow visualization technique using a large capacitor as the power source was proposed. Electric current discharged from capacitors was used to heat a fine metal wire suspended in the flow field. The oil droplets attached to the wire were vaporized and smoke filaments followed the flow motions. A digital camera was used to record the images of the smoke filaments. The actions of discharging and camera shutter were triggered by signals from a micro-controller to ensure the accurate timing. Clear images of the streaklines were captured at a free-stream velocity up to 12.9 m/s, much higher than the limits of the existing techniques.

Linear, nonlinear dynamics, and sensitivity analysis of a vibratory ring gyroscope

Dong-Dong Liang, Xiao-Dong Yang, Wei Zhang, Yuan Ren, Tianzhi Yang

2018, 8(6): 393 -403. doi: 10.1016/j.taml.2018.06.001

[Abstract] (102) [FullText HTML] (52) [PDF 3877KB] (10)

Abstract:
The linear and nonlinear dynamic responses of a vibratory ring gyroscope are investigated in this study focusing on the response mechanism of such a vibratory gyroscope. It is found that the nonlinear equations governing the drive and sense directions are coupled through both inertial linear and geometric nonlinear terms. Nonlinear responses are studied based on the full coupled nonlinear dynamic equations. The varying amplitude on the sense direction is analyzed for different input angular rates. The effect of nonlinearity on the ring gyroscope system is performed by comparing the results of nonlinear responses to those of linear responses. The contributions of some parameters to the amplitude responses and gyroscope sensitivity are analyzed, the conclusions of which provide guidelines to improve the sensitivity of the vibratory ring gyroscopes.

Structure-preserving approach for infinite dimensional nonconservative system

Weipeng Hu

2018, 8(6): 404 -407. doi: 10.1016/j.taml.2018.06.002

[Abstract] (95) [FullText HTML] (54) [PDF 2433KB] (13)

Abstract:
The current structure-preserving theory, including the symplectic method and the multi-symplectic method, pays most attention on the conservative properties of the continuous systems because that the conservative properties of the conservative systems can be formulated in the mathematical form. But, the nonconservative characteristics are the nature of the systems existing in engineering. In this letter, the structure-preserving approach for the infinite dimensional nonconservative systems is proposed based on the generalized multi-symplectic method to broaden the application fields of the current structure-preserving idea. In the numerical examples, two nonconservative factors, including the strong excitation on the string and the impact on the cantilever, are considered respectively. The vibrations of the string and the cantilever are investigated by the structure-preserving approach and the good long-time numerical behaviors as well as the high numerical precision of which are illustrated by the numerical results presented.

Vibration of two-dimensional hexagonal boron nitride

Jianpeng Yi, Lifeng Wang, Yiqing Zhang

2018, 8(6): 408 -414. doi: 10.1016/j.taml.2018.06.003

[Abstract] (71) [FullText HTML] (57) [PDF 2835KB] (9)

Abstract:
The dynamic behavior of two-dimensional nanostructures is important to the future application of nano devices. The vibrational behaviors of single-layered hexagonal boron nitride (h-BN) are studied by molecular dynamics simulation and continuum plate model. The bending stiffness and Poisson's ratios of h-BN along zigzag direction and armchair direction are calculated. H-BN is softer compared with graphene. The continuum plate model can predict the vibration of h-BN with four edge-clamped boundary conditions well. The electric fields in different directions have obvious influence on the vibration of h-BN. The natural frequency of h-BN changes linearly with the electric field intensity along the polarization direction. The natural frequency of h-BN decreases with the increase of electric field intensity along both positive and negative non-polarization direction. While the natural frequency of h-BN increases with the increase of electric field intensity along both positive and negative transverse electric field.

Dynamic modeling of spacecraft solar panels deployment with Lie group variational integrator

Long Bai, Xinsheng Ge

2018, 8(6): 415 -424. doi: 10.1016/j.taml.2018.06.005

[Abstract] (63) [FullText HTML] (39) [PDF 3283KB] (11)

Abstract:
The spacecraft with multistage solar panels have nonlinear coupling between attitudes of central body and solar panels, especially the rotation of central body is considered in space. The dynamics model is based for dynamics analysis and control, and the multistage solar panels means the dynamics modeling will be very complex. In this research, the Lie group variational integrator method is introduced, and the dynamics model of spacecraft with solar panels that connects together by flexible joints is built. The most obvious character of this method is that the attitudes of central body and solar panels are all described by three-dimensional attitude matrix. The dynamics models of spacecraft with one and three solar panels are established and simulated. The study shows Lie group variational integrator method avoids parameters coupling and effectively reduces difficulty of modeling. The obtained continuous dynamics model based on Lie group is a set of ordinary differential equations and equivalent with traditional dynamics model that offers a basis for the geometry control.

Jump rule for edge impacts of rolling prisms

Zhen Zhao, Nannan Wang, Caishan Liu

2018, 8(6): 425 -430. doi: 10.1016/j.taml.2018.06.007

[Abstract] (68) [FullText HTML] (39) [PDF 2987KB] (16)

Abstract:
We study experimentally and theoretically the planar dynamics of purely rolling prisms on a rough ramp, where the rolling motion is interrupted intermittently by edge impacts. The experiments were carried out for prisms made of different materials and having different geometries. We found that the angular velocities of the rolling prisms are material-independent, but they change significantly with their geometry. We modelled the dynamics of edge impacts by considering a so-called detachment front propagating across the contact interface. The detachment front represents the moving boundary between a detached region and a stress region that coexist within the interface plane. The theoretical analysis indicates that the detachment front can be characterized by a scale number, whose value converges to 0.4050 for prisms having large number of edges. A new jump rule for edge impacts is then developed, by which we can accurately reproduce the experimental observations, and explain why the motion of the prism is material-independent.

Article

Head-on collision between two hydroelastic solitary waves with Plotnikov-Toland's plate model

M.M. Bhatti, D.Q. Lu

2018, 8(6): 384 -392. doi: 10.1016/j.taml.2018.06.009

[Abstract] (98) [FullText HTML] (45) [PDF 3122KB] (20)

Abstract:
Head-on collision between two hydroelastic solitary waves propagating at the surface of an incompressible and ideal fluid covered by a thin ice sheet is analytically studied by means of a singular perturbation method. The ice sheet is represented by the Plotnikov-Toland model with the help of the special Cosserat theory of hyperelastic shells and the Kirchhoff-Love plate theory, which yields the nonlinear and conservative expression for the bending forces. The shallow water assumption is taken for the fluid motion with the Boussinesq approximation. The resulting governing equations are solved asymptotically with the aid of the Poincar

\begin{document}$\acute{\rm{e}}$\end{document}

-Lighthill-Kuo method, and the solutions up to the third order are explicitly presented. It is observed that solitary waves after collision do not change their shapes and amplitudes. The wave profile is symmetric before collision, and it becomes, after collision, unsymmetric and titled backward in the direction of wave propagation. The wave profile significantly reduces due to greater impacts of elastic plate and surface tension. A graphical comparison is presented with published results, and the graphical comparison between linear and nonlinear elastic plate models is also shown as a special case of our study.