bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational Modelling of Sloshing in Liquefied Natural Gas Tank
Authors: Foong Shen Yang , Jin Yuting , Chai Shuhong , Chin Christopher , Marcollo Hayden
Published: October 2017

Sloshing in the tank of liquefied natural gas (LNG) carriers has recently attracted immense attention due to the rise in demand for LNG transportation. It occurs in partially filled tanks and is capable of inflicting severe damage to the tank’s interior. One effective method to dampen sloshing activities is by introducing baffles into the tank. In this paper, the nature of sloshing has been investigated using finite volume based unsteady Reynolds Averaged Navier-Stokes (URANS) method. Good correlation was achieved between the results obtained from the presented computations and past studies, demonstrating the feasibility of the established numerical modelling approach. Employing similar computational method, two-dimensional (2D) sloshing computations were performed for different baffle additions at varying filling levels. Observations were made in the baffled tanks where an increase in the number of baffles would cause the sloshing activities to magnify if the baffle height was significantly lower than the filling level. When comparing the 2D and 3D computational results, close resemblance of the average pressure profile and maximum impulsive loads had suggested that 2D simulations are feasible to model sloshing induced loads in a 3D tank.
Joint Time-Frequency Analysis of Small Scale Ocean Storms via the Harmonic Wavelet Transform
Authors: Laface Valentina , Arena Felice , Kougioumtzoglou Ioannis A. , Maximiano dos Santos Ketson Roberto
Published: October 2017

The paper focuses on utilizing the Harmonic Wavelet Transform (HWT) for estimating the evolutionary power spectrum (EPS) of sea storms. A sea storm is considered herein as a non-stationary stochastic process with a time duration of the order of days. The storm evolution can be represented in three stages: the growth, the peak and the decay. Specifically, during growth the intensity of the wave increases with time until reaching the apex, and then decreases. The analysis is carried out by processing the time series of the free surface elevation recorded at the Natural Ocean Engineering Laboratory of Reggio Calabria, Italy. A peculiarity of the NOEL lab is that a local wind from NNW often generates sea states consisting of pure wind waves that represent a small scale model, in Froude similarity, of ocean storms (www.noel.unirc.it). The main focus of the paper is, first, to acquire a joint time-frequency representation of the storm via estimating the associated EPS, and second, to explore the variability in time of the spectrum and of the dominant frequencies of the storm. The EPS is estimated by utilizing a non-stationary record of the sea surface elevation during a storm recorded at NOEL lab.

Further, in this paper, the standard representation of sea storms is also considered. That is, the non-stationary process is represented as a sequence of stationary processes (sea states or buoy records), each of them characterized by an intensity defined by a significant wave height Hs and by a duration Δt. During the time interval Δt the sea surface elevation is considered stationary and the frequency spectrum may be computed via the Fast Fourier Transform (FFT). Results obtained following this procedure, which can be considered essentially as a brute-force application of the short-time FT, are compared with those obtained via a HWT based joint time-frequency analysis.
Experimental Research on Hydroelasto-Buckling Response of Ship Model in Extreme Wave by Changing Wave Length
Authors: Liu Weiqin , Wang Songbo , Song Xuemin
Published: October 2017

Extreme wave used to damage ship structures in the ocean by generating buckling midship due to huge wave height. On the one hand, it is very costly to recreate a real ship test for the study of extreme wave conditions. On the other hand, it is difficult to carry out tests on a common scale model in tank waves, because such waves are too small to damage the ship model. Thus far, no method of simulation has been proposed to study this problem because the dynamic ultimate strength of the ship involves strong coupling between the nonlinearity in the ship structure and waves. Therefore, a hydroelasto-buckling experimental method is proposed to study the dynamic ultimate strength of the ship and dynamic course of collapse of the structure in this paper, the effect of extreme wave length on hydroelasto-buckling response is focused analysis. Here, a hydroelasto-buckling ship model is first designed, and a test program is determined. A buckling hinge that can collapse under the load of the tank wave is used to connect two ship girders with a hinge joint. Then, a number of extreme tank waves are generated by changing their wave length to simulate an extreme ocean wave. The dynamic rotation angle, bottom water press and acceleration at midship are measured in the experiment. Importantly, the relationship between structural response and wave length is analyzed. The structural response involves encountering the rotation deformation induced by the wave load and whipping the rotation deformation induced by natural structural oscillations.
Static and Dynamic Analysis Methods of Position-Keeping Capability for Offshore Supply Vessels With Voith-Schneider Propellers
Authors: Detlefsen Ole , Theilen Lasse , Abdel-Maksoud Moustafa
Published: October 2017

This paper presents a static and a time-domain method to assess the position-keeping capability of monohull vessels. For the static analysis method, the equlibrium between mean environmental loads and available actuator forces is determined. In case of the dynamic assessment, the motions of the fully actuated ship in all degrees of freedom are simulated in time domain and evaluated by criteria regarding the position and heading of the ship. After first results from validation tests an exemplary application is shown by assessing the positioning capability of a Voith-Schneider propelled offshore supply vessel.
A Structure Preserving Power System Frequency Model for Dynamic Positioning Vessels
Authors: Dahl Andreas R. , Skjetne Roger , Johansen Tor A.
Published: October 2017

This paper adapts a structure preserving model to on-board power plants. The model, originally developed for land-based power systems, is expanded for the larger frequency range allowable to on-board plants. State-space equations are developed from first principles and transformed to a form suitable for analysis and computer implementation. Recommendations for parameter selection are given. An example plant scenario is simulated both in the proposed framework and in a higher fidelity model for comparison.
Preliminary Evaluation of the Effectiveness of Using Artificial Reefs to Reduce Breaking Wave Impact on Offshore Structures
Authors: Loedsen Andersen Charlotte , Skov Milthers Ida , Caroee Kristoffersen Julie , Georgakis Christos Thomas , Tao Longbin
Published: October 2017

Waves breaking on offshore platforms can have damaging consequences for the structure and for the safety of the people working on it. Recent unexpected extreme wave events have shown the effects that breaking waves have on offshore platforms.

In this paper, the results from a scaled experimental investigation conducted the Newcastle University wind, wave and current tank, are presented. With these tests, the effectiveness of using artificial reefs to avoid or lessen the effects of breaking wave activity is examined. Four different types of artificial reefs are tested and their effects are compared to a reference test with no artificial reef. The comparison is based on the changes of the size and location of the maximum wave amplitude, the maximum displacement of a scaled platform and the artificial reef’s ability to dissipate wave energy.

Overall, the results show that placing the rectangular reef in the tank produces the most promising results. However, it is also shown that placing any one of the artificial reefs in the tank will affect a change in the wave motion. Thus, this investigation shows that the use of an artificial reef could be a step in securing a higher level of protection for personnel and operations.
Life Extension of Ageing Offshore Structures: A Framework for Remaining Life Estimation
Authors: Aeran Ashish , Siriwardane Sudath C. , Mikkelsen Ove , Langen Ivar
Published: October 2017

The remaining life estimation of ageing structures has been identified as a growing challenge in the oil and gas industry. Although the available guidelines provide a general fatigue assessment process, it is necessary to have more detailed guidelines by adding relevant theories and models which can capture the time-dependent structural degradation more precisely. To address this, a new framework is proposed in this paper. The proposed framework provides recommendations on various issues such as simulation of structural degradation, loading history, effect of localized corrosion, selection of a suitable fatigue strength curve and fatigue damage theories. Recently developed precise fatigue damage theory is also included in the proposed framework.
Properties of Rogue Waves and the Shape of the Ocean Wave Power Spectrum
Authors: Osborne Alfred R. , Ponce de León Sonia
Published: October 2017

We discuss a method for the determination of the shape of the ocean wave power spectrum that is based on the physics of the modulational instability for the nonlinear Schrödinger and the Zakharov equations. We find that the form of the spectrum includes an enhanced spectral peak and modulational channels that extend to both high and low frequency. Furthermore, this fundamental shape of the spectrum is found to also be contained in the kinetic equation commonly used for wind-wave models provided that the full Boltzmann four-wave interactions are included. We discuss a number of numerical simulations that demonstrate the modulational form of the power spectrum. We furthermore discuss how the enhanced spectral peak governs the formation of rogue wave packets. We provide ways to compute the properties of the rogue waves directly from the nonlinear spectrum of analyzed time series data or from wave forecasts and hindcasts.
Research on Ship Structural Fatigue Damage Under Nonlinear Wave Bending Moment
Authors: Yue Jingxia , Peng Lihua , Mao Wengang , Zhang Chi , Dong Wei , Zhu Zhentao
Published: October 2017

Loads acting on ship structures are complex and randomly over time and the nonlinear effect caused by wave loading is one of the research focus. The linear and nonlinear vertical wave bending moment (VBM) in different speeds and sea states and their effects on ship structural fatigue strength were investigated for a flat container with high ratio of width to depth. The VBM under the linear regular waves and irregular waves were calculated based on the three dimension (3D) potential theory. The considered nonlinear wave loading was caused by sea pressure near the mean free surface as well as the geometric nonlinearity. Hydrodynamic calculations in regular wave were presented to figure out the frequency response function (FRF) of VBM in the mid-ship section. Irregular waves were verified to obtain the VBM history in 4 sea states. What’s more, VBMs from a segmented elastic model test were obtained to investigate the influence of nonlinearity. On the basis of the wave loadings obtained from simulation and test, the hotspot stress histories under irregular waves were deduced in time domain by using the beam theory. Fatigue cumulative damage per hour under several random sea states were obtained on the basis of the rain-flow counting and S-N curve. Based on the fatigue damage from the numerical analysis and model test, it is believed that speeds and significant wave height have a positive correlation with the fatigue damage of ship structures. A good agreement was obtained between the numerical analysis values and the low frequency part of the test and the nonlinear analysis in the simulation could offer reasonable prediction for the fatigue damage caused by the wave frequency response. Also shown as the test result, fully nonlinearities have a great contribution to the fatigue damage.
A Numerical Study on Slow-Drift Motion and Wave-in-Deck Impact Event of a Tension Leg Platform in Extreme Waves
Authors: Nam Bo-Woo , Hong Sa Young , Kim Hyun Joe
Published: October 2017

Wave-in-deck impacts in extreme waves can cause a serious damage on both fixed and floating offshore structures. In particular, tension leg platform (TLP) can be exposed to frequent wave-in-deck impact events due to good vertical motion performances as well as wave amplifications inside columns. In this study, the wave-in-deck impact event as well as slow-drift motion response of a tension leg platform are numerically investigated. First, the experimental observations of the wave-in-deck events are suggested based on the model tests of a TLP, where the extreme waves of 100-year and 1,000 year return periods were tested. Both weak and strong wave-in-deck events are described in detail. Then, time-domain simulations were carried out to predict the motion responses of the TLP and wave-in-deck events. Appropriate numerical modeling is suggested to simulate the TLP motion responses. The numerical prediction results are directly compared with the model test data. Discussion is made on the appropriate numerical modeling for the prediction of the wave-in-deck impact event.
Benchmark Studies of Wave Run-Up and Forces on a Truncated Square Cylinder
Authors: Ali Md Ashim , Peng Heather , Qiu Wei
Published: October 2017

This paper presents the numerical results of wave run-up and loading on a single truncated square cylinder using the open source computational fluid dynamics software, OpenFOAM. The computed wave elevations on the cylinder in waves with various steepness and periods were compared with experimental data. The work focused on verification and validation studies. Parameters that affect the numerical solutions, including grid resolution, grid distribution over the wavelength and wave height, and time step, were investigated.
Study of an Entrapped Air Pocket due to Sloshing Using Experiments and Numerical Simulations
Authors: Firoozkoohi Reza , Abrahamsen Bjørn Christian , Faltinsen Odd Magnus
Published: October 2017

The capability of the OpenFoam software to model slamming where air is entrapped between the free surface and the structure is investigated. The test case studied is a previously studied phenomenon, where an air pocket is entrapped between the free surface and the upper corner of a rectangular tank during sloshing. The air is entrapped due to the shape of the wave approaching the roof. The air pocket is compressed and starts to oscillate. The oscillations resemble the free oscillations of a mass spring system. OpenFoam results are compared with experiments and a numerical method based on a boundary element method (BEM) both of which are available from the previous study. In this work a compressible VOF (Volume Of Fluid) Eulerian two-phase mixture flow solver called compressible InterFoam from OpenFOAM package is used to perform the simulations. The sensitivity of the results to numerical parameters is addressed.
Wave Load Prediction on a Stationary Bergy Bit Near a Fixed Offshore Platform
Authors: Seo Dong Cheol , Sayeed Tanvir , Zaman M. Hasanat , Akinturk Ayhan
Published: October 2017

Offshore oil and gas operations conducted in harsh environments such offshore Newfoundland may pose additional risks due to collision of smaller ice pieces and bergy bits with the offshore structures, including their topsides in the case of gravity based structures particularly in extreme waves. In this paper, CFD (Computational Fluid Dynamics) prediction for wave loads acting on a bergy bit around a fixed offshore platform is presented. Often the vertical column of a gravity based structure is designed against ice collisions, if operating in such an environment. In practices, topsides are usually protected by being placed sufficiently high from the still water level, away from the reach of the bergy bits. This vertical clearance between the still water level and the topside deck is known an air gap. Hence, the amount of the air gap planned for such an offshore structure is an important factor for the safety of the topsides at a given location. In this study a CFD method is applied to estimate the dynamic response of the bergy bit and provide a reliable air gap to reduce the potential risk of the bergy bit collision. In advance of more complex collision simulations using a free-floating ice for the airgap design, CFD analysis of wave load prediction on a stationary bergy bit is carried out and reported in this paper. In the experiments and CFD simulations, the location of the bergy bit is changed to quantify the change of wave load due to the hydrodynamic interaction between the bergy bit and the platform. Finally, the results of the CFD simulations are compared with the relevant experiment results to confirm the simulation performance prior to the free floating bergy bit simulations.
CFD Study of Fully Coupled Mooring and Riser Effects on Vortex-Induced Motion of Semi-Submersible
Authors: Jang Hyunchul , Kyoung Johyun , Kim Jang Whan , Yan Hongmei , Wu Guangyu
Published: October 2017

Vortex Induced Motion (VIM) of column-stabilized floaters has created substantial design and operational challenges to the mooring and risers. VIM design criteria are typically obtained from a towing tank model test. But in the model test, moorings and risers are not physically modeled and the lateral stiffness from moorings and risers is modeled simply with linear springs. Recent field measurements of semi-submersibles and truss spars indicate that the overly-simplified mooring and riser setup in model test could lead to overly-conservative VIM design criteria. In this study, CFD simulations were employed to investigate the effects of actual mooring and riser configurations on VIM response of deep draft semi, such as asymmetric restoring and hydrodynamic damping. Descriptions of the CFD and mooring and riser modeling and comparisons of the VIM response with the simplified setups are presented, along with a discussion on the implications of the mooring and riser simplification in the model test are presented.
A Step Towards a Reduced Order Modelling of Flow Characterized by Wakes Using Proper Orthogonal Decomposition
Authors: Fonn Eivind , Rasheed Adil , Tabib Mandar , Kvamsdal Trond
Published: October 2017

High fidelity simulations of flow might be quite demanding, because they involve up to O(106 – 109) degrees of freedom and several hours (or even days) of computational time, also on powerful hardware parallel architectures. Thus, high-fidelity techniques can become prohibitive when we expect them to deal quickly and efficiently with the repetitive solution of partial differential equations. One set of partial differential equation that we encounter on a regular basis is the Navier Stokes Equation which is used to simulate flow around complex geometries like sub-sea structures. To address the issues associated with computational efficiency, a field of Reduced Order Modelling is evolving fast. In this paper we investigate Proper Orthogonal Decomposition as a potential method for constructing reduced bases for Reduced Order Models. In the case of flows around cylindrical bodies we found that only a few modes were sufficient to represent the dominant flow structures and energies associated with them making POD to be an attractive candidate for bases construction.
Experimental and Numerical Study on the Flow Reduction in the Moonpool of Floating Offshore Structure
Authors: Yoo Seon Oh , Kim Hyun Joe , Lee Dong Yeon , Kim Booki , Yang Seung Ho
Published: October 2017

This paper presents the efforts of experimental and numerical studies to reduce internal flow of moonpool.

Drillships are equipped with a vertical opening at the center of the hull called ‘moonpool.’ Recently, the moonpools are getting longer and wider for the higher operability. With this trend, violent internal flows are getting more concerned in terms of the safety and operability, which have been reported during the operations even in mild seas. Also, it is well known that the internal flow gives higher resistance during the transit of drillship. Therefore, there have been a number of motivated researches on the reason and the source of excitation, the pattern of the internal flow and the way to suppress it.

Typically an internal flow of the moonpool has two types of oscillation modes: piston- and sloshing-mode. The excited oscillations of water and resultant internal flows are highly dependent on the shape of the moonpool, partly due that the resonant periods are varied with the size and shape of the moonpool. However, since the shape and size of the drillships are quite standardized, there may be no room for the change of shape to reduce the inflow from the bottom of moonpool. Therefore, more efforts have been made to develop the damping devices such as splash plates, which can be easily installed inside of the moonpool.

In this study, to see the effect of larger damping devices, a series of experimental and numerical study was carried out for the four moonpool designs; the ordinary plain moonpool, the moonpool with a recess deck, the moonpool with an isolated recess deck (island deck) and moonpool with a combination of island deck, splash plates and wave absorber. From the model tests, it was found that the internal flow of the moonpool was significantly reduced by the application of the wave absorber. In case of the moonpool with the island deck, the sloshing mode oscillations was not observed due to the gap flow between the inner wall of the moonpool and the recess, while the piston mode oscillations were remained unchanged. For the in-depth understanding of the flow behaviors and characteristics, the internal flow of the moonpool has been investigated using RANS based CFD code. The various moonpool designs were simulated to identify the effect of each device for the internal flow reduction of the moonpool. The CFD analysis results with regular waves, the water surface responses inside moonpool such as the flow pattern and resonance frequency were compared with model test results and showed reasonably good agreements.
A Method for Fatigue Evaluation of Trimaran Cross Structure With the Influence of Slamming
Authors: Li Zhe , Ren Huilong , Jin Kai
Published: October 2017

Slamming is a highly non-linear phenomenon between hull structure and wave. Due to the special structure of trimaran, the slamming mode is extremely different from that of traditional vessel. Besides bow emergence and enter, the slamming phenomenon of the out shell at the cross structure is also obvious. In conventional hull structure fatigue strength evaluation, the slamming load is usually not considered. However, the slamming problem is unavoidable at danger load cases, and the stress concentration of the trimaran cross structure is serious. So it is dangerous to ignore the existence of slamming in serious load cases when evaluating the structural fatigue strength. Therefore, it is necessary to study the contribution of slamming load to fatigue damage.

In this paper, a practical method for calculating and analyzing is presented to consider the effect of slamming on the fatigue strength of the trimaran cross structure to ensure that the fatigue life of the structure is closer to the true value. According to the linear theory, the relative motion and relative speed of the hull in wave and the stress response of the wave load on the structure are calculated firstly. Then, the stress response of the non-linear out shell slamming force is calculated. The linear response and non-linear response are combined. And the stress response time history under the combined action of slamming and wave load are obtained. Finally, the fatigue damage of the structure under dangerous operating conditions is calculated by the rain flow counting method. And the contribution value of the slamming load to the structural damage degree is calculated. The paper will put forward some reference suggestions for fatigue study calculation and evaluation of Trimaran cross structure with the influence of slamming.
Wave Drift Forces and Low Frequency Damping on the Exwave Semi-Submersible
Authors: Fonseca Nuno , Stansberg Carl Trygve
Published: October 2017

The paper presents realistic horizontal wave drift force coefficients and low frequency damping coefficients for the Exwave semi-submersible under severe seastates. The analysis includes conditions with collinear waves and current.

Model test data is used to identify the difference frequency wave exciting force coefficients based on a second order signal analysis technique. First, the slowly varying excitation is estimated from the relationship between the incoming wave and the low frequency motion using a linear oscillator. Then, the full quadratic transfer function (QTF) of the difference frequency wave exciting forces is defined from the relationship between the incoming waves and the second order force response. The process identifies also the linear low frequency damping.

The paper presents results from cases selected from the EXWAVE JIP test matrix. The empirical wave drift coefficients are compared to potential flow predictions and to coefficients from a semi-empirical formula. The results show that the potential flow predictions largely underestimate the wave drift forces, especially at the low frequency range where severe seastates have most of the energy.
CFD Based Multi-Disciplinary Optimization Design of High-Performance Deep Sea Seismic Vessel
Authors: Xiaofei Mao , Wenxu Zhang , Jiankui Qian , Minghao Wu
Published: October 2017

This paper focuses on the application of a ship hull form multi-disciplinary optimization (MDO) system based on the computational fluid dynamics (CFD). Using the iSIGHT software, the MDO system integrates an automatic geometry transformation program and high-fidelity CFD solvers for different sub-disciplines. Hydrodynamics analysis subsystem includes resistance, seakeeping and stability modules. The resistance and seakeeping is analyzed by commercial potential-flow CFD codes, the stability is assessed by in-house code. The geometry variation output can be automatically used by the numerical solvers. By means of the design of experiment (DOE) technique, a neural network metamodel is trained to predict short term motion response of the derived ships efficiently.

The system has been used in a seismic vessel’s hull form optimization to minimize the resistance and maximize the long term seakeeping operability index. Meanwhile, the stability in waves is concerned as a constraint. The hybrid MIGA-NLPQL optimization algorithm is applied for a global-to-local search in resistance optimization. For the synthesis optimization, a Pareto optimal solution set has been obtained and the final solution is achieved by trade-off analysis of the solution set. The entire automatic optimization process can be used for the preliminary design of new high performance vessels.
CFD Modeling of Subsea Gas Releases Using an Improved Bubble Drag Law
Authors: Kara Mustafa C. , Parsi Mazdak , Jatale Anchal , Sharma Partha P.
Published: October 2017

A subsea gas leakage from pipelines, risers, gas transport pipelines or blowouts from oil and gas wells forms dispersion of gas as it rises to the surface. Accidental subsea gas release scenarios of hydrocarbons pose a significant risk for the safety and integrity of offshore production or drilling units. With recent advancements in technology, the number of subsea installations and pipelines increases substantially at larger water depths. For the large depths, it is crucial to understand the quantitative impact of the gas release as the classical integral bubble plume models fail to predict gas flux and gas distribution through the ocean surface and the resulting surface flows. A quantitative multiphase computational fluid dynamics (CFD) model can be implemented to simulate large scale bubble plumes by tracking bubbles and free surface in a Eulerian-Lagrangian fashion. In this paper, the coupled discrete phase (DPM) and volume of fluid (VOF) multiphase modeling approach has been utilized for modeling subsea gas releases. This study evaluates an improved drag law for gas-liquid two phase bubbly flow based on consideration of bubble deformation. The model successfully predicts a wide range of experimental measurements at model scale and is also applied to gas release at large ocean depths to study the validity of the model for realistic scenarios.
Silver engineered nanomaterials and ions elicit species-specific O2 consumption responses in plant growth promoting rhizobacteria
Authors: Lewis Ricky W. , Unrine Jason , Bertsch Paul M. , McNear David H.
Published: October 2017

Metal containing engineered nanomaterials (ENMs) are now commonly used in various industrial and commercial applications. Many of these materials can be transformed during waste water treatment and ultimately enter terrestrial ecosystems via agriculturally applied biosolids. It is unclear how agriculturally important soil microbes will be affected by exposure to environmentally relevant, sublethal concentrations of ENMs and their transformation products (i.e., ions, aggregates, etc.). A method was developed, which puts O2 consumption responses in terms of viability, and tested by examining the toxic effects of Ag+, Zn2+, and Ni2+ ions on the plant growth promoting rhizobacterium (PGPR) Bacillus amyloliquefaciens GB03. The method was then used to examine the toxicity of Ag+, as-synthesized polyvinylpyrrolidone-coated silver ENM (PVP-AgENMs), and 100% sulfidized AgENM on B. amyloliquefaciens GB03, and two additional PGPRs Sinorhizobium meliloti 2011, and Pseudomonas putida UW4. S. meliloti was found to have the highest LC50 for Ag+ and PVP-AgENMs (6.6 and 207 μM, respectively), while B. amyloliquefaciens and P. putida exhibited LC50's for Ag+ and PVP-AgENMs roughly half those observed for S. meliloti. The authors observed species-specific O2 consumption responses to ENM and ion exposure. PVP-AgENMs were less toxic than ions on a molar basis, and abiotic dissolution likely explains a significant portion of the observed toxic responses. Our results suggest microbes may exhibit distinct metabolic responses to metal and ENM exposure, even when similar LC50's are observed. These findings together illustrate the importance of understanding species-specific toxic responses and the utility of examining O2 consumption for doing so.
On the authenticity of individual dynamic binaural synthesis
Authors: Brinkmann Fabian , Lindau Alexander , Weinzierl Stefan
Published: October 2017

A simulation that is perceptually indistinguishable from the corresponding real sound field could be termed authentic. Using binaural technology, such a simulation would theoretically be achieved by reconstructing the sound pressure at a listener's ears. However, inevitable errors in the measurement, rendering, and reproduction introduce audible degradations, as it has been demonstrated in previous studies for anechoic environments and static binaural simulations (fixed head orientation). The current study investigated the authenticity of individual dynamic binaural simulations for three different acoustic environments (anechoic, dry, wet) using a highly sensitive listening test design. The results show that about half of the participants failed to reliably detect any differences for a speech stimulus, whereas all participants were able to do so for pulsed pink noise. Higher detection rates were observed in the anechoic condition, compared to the reverberant spaces, while the source position had no significant effect. It is concluded that the authenticity mainly depends on how comprehensive the spectral cues are provided by the audio content, and the amount of reverberation, whereas the source position plays a minor role. This is confirmed by a broad qualitative evaluation, suggesting that remaining differences mainly affect the tone color rather than the spatial, temporal or dynamical qualities.
Understanding and managing sleep disruption in children with fetal alcohol spectrum disorder
Authors: Hanlon-Dearman Ana , Chen Maida Lynn , Olson Heather Carmichael
Published: October 2017

Accumulating evidence has revealed high rates of sleep disruption among children with fetal alcohol spectrum disorder (FASD). Multiple animal and clinical studies have found a clear association between sleep problems and prenatal alcohol exposure, and recent research is beginning to characterize the types and extent of sleep disruption in FASD. Nevertheless, sleep disruption in children with FASD often goes unrecognized or is treated without referring to an evidence base. Children’s disrupted sleep interferes with parental sleep and increases caregiver burden, which is of particular importance for families raising children with FASD, a group with very high levels of caregiving stress. The literature supporting an association between sleep problems and deficits in emotional, behavioral, and cognitive function in children is compelling, but needs further investigation in children with FASD. This paper will review the current state of knowledge on sleep in FASD and recommend a rational approach to sleep interventions for affected children and their families.
Hypersensitivity reactions to low molecular weight heparins: different patterns of cross-reactivity in 3 patients
Authors: Juricic Nahal Danica , Cegec Ivana , Erdeljic Turk Viktorija , Makar Ausperger Ksenija , Kraljickovic Iva , Simic Iveta
Published: October 2017

Low molecular weight heparins (LMWHs) are used for a variety of indications. The most common type of hypersensitivity reactions to LMWHs are delayed-type hypersensitivity reactions (DHR). Immediate-type hypersensitivity reactions (IHR) occur only sporadically. Cross-reactivity of different LMWHs is a common and unpredictable problem. We present 2 cases of patients who developed DHR to nadroparin and enoxaparin, respectively. The third case presents a patient who developed IHR to nadroparin. Skin tests confirmed the hypersensitivity in all cases. In the cases of DHR, a skin test negative LMWH was identified and was tolerated in a challenge test. In the IHR case, cross-reactivity to all tested LMWHs was established. We hypothesize that the degree of cross-reactivity might depend on the type of hypersensitivity reaction with immediate reactions linked to more extensive cross-reactivity than delayed reactions. This is important to consider because, at least in some cases, a safe alternative LMWH can be identified.
Bounded orbits for photons as a consequence of extra dimensions
Authors: González P. A. , Olivares Marco , Vásquez Yerko
Published: October 2017

In this paper, we study the geodesic structure for a geometry described by a spherically symmetric four-dimensional (4D) solution embedded in a five-dimensional (5D) space known as a brane-based spherically symmetric solution. Mainly, we have found that the extra dimension contributes to the existence of bounded orbits for the photons, such as planetary and circular stable orbits that have not been observed for other geometries.
Negative differential resistance and magnetoresistance in zigzag borophene nanoribbons
Authors: Liu Jiayi , Wu Jiaxin , Chen Changpeng , Han Lu , Zhu Ziqing , Wu Jinping
Published: October 2017

Since borophene has been grown experimentally, its extraordinary characteristics have attracted more and more attentions. In this paper, we construct pristine zigzag-edged borophene nanoribbons (ZBNRs) of different widths to study the transport properties, using the first-principles calculations. The differences of the quantum transport properties are discussed, where even-N ZBNRs and odd-N ZBNRs have different current–voltage relationships. Especially, the negative differential resistance (NDR) can be observed within certain bias range in 5-ZBNR and 7-ZBNR, while 6-ZBNR behaves like a metal whose current rises with the increase of the voltage. Moreover, borophene nanoribbon shows interesting magnetic transport properties. The spin-filtering effect can be revealed when the two electrodes have opposite magnetization directions. Besides, the magnetoresistance effect appears to exist in even-N ZBNRs and the maximum value can reach 70%. The mechanisms of these phenomena are proposed in detail.
An investigation into premium and marginal pavement aggregates from New Zealand
Authors: Li W. , Wilson D. J. , Larkin T. J. , Black P. M.
Published: October 2017

Aggregates used in pavement construction in New Zealand are classified as either premium or marginal depending on their quality. Using marginal materials in a pavement may cause significant problems, such as fatigue cracking, rutting and swelling. One likely reason for these problems can be the mineralogical composition of the aggregates, particularly if they contain swelling minerals. The present paper investigates how swelling minerals can affect the properties of New Zealand aggregates. Standard engineering tests were conducted on five New Zealand materials, two of which are regarded as meeting the local NZTA (New Zealand Transport Agency) M4 premium specification and three regarded as marginal. The geological properties and mineralogical compositions of all aggregates were also determined by petrographic examination and X-ray powder diffraction analysis (XRD), and the swelling potential identified using a one-dimensional swelling test. It was found that clay minerals generally exist in all five aggregates and swelling minerals in the three marginal aggregates and a premium aggregate; the last mentioned also proved to have a high swelling potential. It is concluded that the test methods specified by the NZ standard and currently used to distinguish between and categorize premium and marginal aggregates appear insufficient when they are water saturated. Additional test methods (XRD and a swelling test) are suggested to complement the standard test methods.
Interoperability and Portability Approaches in Inter-Connected Clouds
Authors: Kaur Kiranbir , Sharma DR. Sandeep , Kahlon DR. Karanjeet Singh
Published: October 2017

Inter-connected cloud computing is an inherent evolution of Cloud Computing. Numerous benefits provided by connecting clouds have garnered attraction from the academic as well as the industry sector. Just as every new evolution faces challenges, inter-connected clouds have their own set of challenges such as security, monitoring, authorization and identity management, vendor lock-in, and so forth. This article considers the vendor lock-in problem, which is a direct consequence of the lack of interoperability and portability. An extensive literature review by surveying more than 120 papers has been done to analyze and categorize various solutions suggested in literature for solving the interoperability and portability issues of inter-connected clouds. After categorizing the solutions, the literature has been mapped to a specific solution and a comparative analysis of the papers under the same solution has been done. The term “inter-connected clouds” has been used generically in this article to refer to any collaboration of clouds which may be from the user side (Multi-clouds or Aggregated service by Broker) or the provider side (Federated clouds or Hybrid clouds). Lastly, two closely related issues (Brokers and Meta-scheduling) and the remaining challenges of inter-connected clouds are discussed.
The Psychology of Superorganisms: Collective Decision Making by Insect Societies
Authors: Sasaki Takao , Pratt Stephen C.
Published: October 2017

Under the superorganism concept, insect societies are so tightly integrated that they possess features analogous to those of single organisms, including collective cognition. If so, colony function might fruitfully be studied using methods developed to understand individual animals. Here, we review research that uses psychological approaches to understand decision making by colonies. The application of neural models to collective choice shows fundamental similarities between how brains and colonies balance speed/accuracy trade-offs in decision making. Experimental analyses have explored collective rationality, cognitive capacity, and perceptual discrimination at both individual and colony levels. A major theme is the emergence of improved colony-level function from interactions among relatively less capable individuals. However, colonies also encounter performance costs due to their reliance on positive feedback, which generates consensus but can also amplify errors. Collective learning is a nascent field for the further application of psychological methods to colonies. The research strategy reviewed here shows how the superorganism concept can serve as more than an illustrative analogy.
Synchronization matters for motor coordination
Authors: Pesce Ibarra Luigi S.
Published: October 2017

Using electroencephalography and electromyography recordings from healthy participants during a visual-depended bimanual coordination task, de Vries and colleagues showed that functional synchronization is important in motor coordination. The authors reported that higher coordination correlated positively with intermuscular synchrony, but correlated negatively with corticomuscular synchrony. They proposed that these two diverse motor systems operate differently depending on task demands. Similar experimental paradigms could identify motor mechanisms in patients with neurological disorders to design novel rehabilitation strategies.
Hypothermia with Extreme Bradycardia following Spinal Cord Infarction of Septic Origin
Authors: Hantson Philippe , Duprez Thierry
Published: October 2017

Among other autonomic dysfunctions complicating acute spinal cord injury, deep hypothermia is rare but may induce serious cardiovascular complications. There are few pharmacological options to influence hypothermia. A 66-year-old woman was transferred to the intensive care unit (ICU) for serious cardiac arrhythmias (atrial fibrillation and asystole) in the context of a deep hypothermia (axillary temperature below 32°C). She had been admitted to the hospital two months before for an acute L4-L5 infectious spondylodiscitis without any initial neurological deficit. After surgery for epidural abscess drainage, she became paraplegic due to spinal cord infarction (from C7 to T6 levels) in the upper territory of the anterior spinal artery. In the ICU, the patient experienced several episodes of asystole and hypotension associated with a core body temperature below 35°C. Common causes of hypothermia (drugs, hypothyroidism, etc.) were excluded. A definitive pacemaker had to be inserted, but hypotension persisted. The prescription of oral progesterone (200 mg·d−1) helped to maintain a core temperature higher than 35°C, with a withdrawal of vasopressors. This case report illustrates that patients with incomplete spinal cord injury may present with delayed and deep hypothermia leading to serious cardiovascular complications. Progesterone could be able to influence positively central and peripheral thermal regulation.
Role of Periapical Diseases in Medication-Related Osteonecrosis of the Jaws
Authors: Rao Nian Jing , Wang Jing Yi , Yu Ru Qing , Leung Yiu Yan , Zheng Li Wu
Published: October 2017

Objective. The present study aimed to investigate the role of periapical diseases in inducing medication-related osteonecrosis of the jaws (MRONJ) using an ovariectomized (OVX) mice model. Materials and Methods. Twenty C57BL/6N female mice were randomly assigned to two groups. All mice were subjected to bilateral ovariectomy and then treated with oncologic dose of zoledronic acid (ZA) or vehicle for twelve weeks. Eight weeks after commence of drug administration, a pulpal exposure (PE) operation was performed on the first right lower molar to induce periapical periodontitis; the contralateral non-PE tooth was used as control. All animals were sacrificed four weeks after pulpal exposure, and the mandibles were harvested for radiological and histomorphometrical analysis. Results. Micro computed tomography (μ-CT) examination demonstrated that periapical diseases significantly increased alveolar bone resorption, and the resorption was greatly attenuated by ZA treatment. Concurrent ZA therapy significantly increased bone density and histological osteocyte necrosis in the presence of periapical lesions. Conclusion. ZA treatment reduced bone absorption resulting from periapical disease but increased the risk of developing MRONJ in the ovariectomized mouse model.
Micronutrient Intake in a Cohort of Italian Adults with Type 1 Diabetes: Adherence to Dietary Recommendations
Authors: Giorgini Marisa , Vitale Marilena , Bozzetto Lutgarda , Ciano Ornella , Giacco Angela , Rivieccio Anna , Calabrese Ilaria , Riccardi Gabriele , Rivellese Angela A. , Annuzzi Giovanni
Published: October 2017

Micronutrients are of fundamental importance in maintaining health status. However, data on their dietary intake are few particularly in persons with diabetes. The aim of this study was to evaluate in adults with type 1 diabetes (T1DM) attending a tertiary-level diabetes center in Southern Italy the intake of micronutrients (both vitamins and minerals) and the adherence to recommendations. Seven-day food records of 60 T1DM patients were analyzed. Micronutrient intake was evaluated based on the Italian food composition tables and expressed as amount per 1000 kcal of energy intake to adjust for possible underreporting. Adherence to recommendations for vitamins A, B6, B12, and C and niacin was acceptable in both sexes (ranging from 77% to 100%). Half of the patients did not adhere to folate recommendation, even less to vitamin E, and no patient reached the recommended intake for vitamin D. As for minerals, adherence was low for potassium and selenium (0–23%); intermediate for zinc, copper, and magnesium; low and intermediate for calcium in men and women, respectively; and low for iron in women. In conclusion, the diet followed by T1DM patients may not have a sufficient content of different micronutrients. Therefore, an adequate intake of low-fat dairy products, fish, legumes, and vegetables should be encouraged as components of a healthier dietary pattern.
New Result on the Critical Exponent for Solution of an Ordinary Fractional Differential Problem
Authors: Zhang Xinguang , Liu Lishan , Wu Yonghong , Cui Yujun
Published: October 2017

We give some background of fractional Cauchy problems and correct an existing result of Cauchy problem for the fractional differential inequality, and we also give an example to illustrate our statement.
Nd:YAG Laser Photodisruption for Multilevel Premacular Hemorrhage due to Isolated Retinal Venous Macroaneurysm
Authors: Sonmez Kenan , Ozcan Pehmen Y.
Published: October 2017

A 55-year-old man presented with sudden deterioration of vision in the right eye. His visual acuity was reduced to hand motion because of a large multilevel premacular hemorrhage. Nd:YAG laser was performed to drain the entrapped hemorrhage under the internal limiting membrane (ILM) and posterior hyaloid face in the macula into the vitreous. Immediately after laser treatment, streaming of red blood cells into the vitreous gel through the perforation site was observed. At the first-month follow-up, BCVA improved to 20/25 and ILM wrinkling was observed at the macula where the preretinal hemorrhage cleared. Fluorescein angiography revealed an isolated retinal venous macroaneurysm located on the macular branch of the superotemporal vein at the bifurcation site. In contrast to retinal arterial macroaneurysms, retinal venous macroaneurysms are quite rare. To the best of our knowledge, this is the first case reported with multilevel premacular hemorrhage caused by an isolated retinal venous macroaneurysm.