bluuebunny/crossref_metadata_2025 huggingface dataset:
Burkholderia pseudomallei-loaded cells act as a Trojan horse to invade the brain during endotoxemia
Authors: Hsueh Pei-Tan , Lin Hsi-Hsun , Liu Chiu-Lin , Ni Wei-Fen , Chen Ya-Lei , Chen Yao-Shen
Published: September 2018

Neurologic melioidosis occurs in both human and animals; however, the mechanism by which the pathogen Burkholderia pseudomallei invades the central nervous system (CNS) remains unclear. B. pseudomallei-loaded Ly6C cells have been suggested as a putative portal; however, during melioidosis, lipopolysaccharide (LPS) can drive disruption of the blood-brain barrier (BBB). This study aims to test whether the Trojan horse-like mechanism occurs during endotoxemia. The expression levels of cerebral cytokines, chemokines and cell adhesion molecules; the activation of astrocytes, microglia and endothelial cells; and the increased vascular permeability and brain-infiltrating leukocytes were evaluated using B. pseudomallei, B. thailandensis, B. cenocepacia and B. multivorans LPS-induced brains. Accordingly, different degrees of BBB damage in those brains with endotoxemia were established. The B. multivorans LPS-induced brain exhibited the highest levels of disruptive BBB according to the above mediators/indicators. Into these distinct groups of endotoxemic mice, B. pseudomallei-loaded Ly6C cells or free B. pseudomallei were adoptively transferred at equal bacterial concentrations (103 CFU). The bacterial load and number of cases of meningeal neutrophil infiltration in the brains of animals treated with B. pseudomallei-loaded Ly6C cells were higher than those in brains induced by free B. pseudomallei in any of the endotoxemic groups. In particular, these results were reproducible in B. multivorans LPS-induced brains. We suggest that B. pseudomallei-loaded cells can act as a Trojan horse and are more effective than free B. pseudomallei in invading the CNS under septic or endotoxemic conditions even when there is a high degree of BBB disruption.
Two-electron redox-active tricyano iron(ii) complex with 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine as a building block for coordination polymers
Authors: Shiga Takuya , Miyamoto Haruka , Newton Graham N. , Oshio Hiroki
Published: September 2018

A new tricyano iron(ii) building unit and three coordination polymers were synthesized, and their structures and magnetic properties were investigated.
Protonation and water exchange kinetics in sandwich polyoxometalates
Authors: Ohlin C. André , Pascual-Borràs Magda
Published: September 2018

The locus of protonation in a sandwich polyoxmetalate is determined and linked to observed reactivities; the implications for reactions on protic metal oxide surfaces are discussed.
Synthesis, structure and magnetic investigations of dinuclear lanthanide complexes based on 2-ethoxycinnamate
Authors: Zouzou Amina , Beghidja Adel , Long Jérôme , Beghidja Chahrazed , Gándara Felipe , Guari Yannick , Larionova Joulia
Published: September 2018

Slow relaxation in dinuclear lanthanide complexes based on 2-ethoxycinnamate.
Determination of cadmium in commercial tobacco by EMFAAS
Authors: Carrone G. , Morzan E. , Tudino M. , Etchenique R.
Published: September 2018

In this work we present the use of EMFAAS (Electrothermal Metallic Furnace Atomic Absorption Spectroscopy) for the determination of Cd in the tobacco cigarettes of five commercial brands.
3D mapping of nanoscale crosslink heterogeneities in microgels
Authors: Karanastasis Apostolos A. , Zhang Yongdeng , Kenath Gopal S. , Lessard Mark D. , Bewersdorf Joerg , Ullal Chaitanya K.
Published: September 2018

The majority of gels exhibit nanoscale spatial variations in crosslink density. We present the first 3D super-resolution microscopy images of dye tagged cross-link distributions in microgels and hydrogels. The morphology of nanoscale features never imaged previously in microgels, are revealed.
Graphene oxide and carbon dots as broad-spectrum antimicrobial agents – a minireview
Authors: Anand Anisha , Unnikrishnan Binesh , Wei Shih-Chun , Chou C. Perry , Zhang Li-Zhi , Huang Chih-Ching
Published: September 2018

Complex antibacterial mechanisms of graphene oxide and carbon dots.
Direct C-4 alkylation of quinazoline N-oxides with ethers via an oxidative cross-coupling reaction under metal-free conditions
Authors: Yang Qin , Lou Minhao , Yin Zhijian , Deng Zhihong , Ding Qiuping , Peng Yiyuan
Published: September 2018

A novel and efficient protocol for the direct C-4 alkylation of quinazoline-3-oxides via radical oxidative coupling between quinazoline 3-oxides and ethers in the presence of TBHP is presented.
First catalyst-free CO2trapping ofN-acyliminium ions under ambient conditions: sustainable multicomponent synthesis of thia- and oxazolidinyl carbamates
Authors: Franz Max , Stalling Timo , Steinert Henning , Martens Jürgen
Published: September 2018

A sustainable multicomponent approach through catalyst-free utilization of carbon dioxide under ambient conditions for the preparation of carbamates is reported.
Mechanics and nanovoid nucleation dynamics: effects of polar functionality in glassy polymer networks
Authors: Elder Robert M. , Long Tyler R. , Bain Erich D. , Lenhart Joseph L. , Sirk Timothy W.
Published: September 2018

We use molecular simulations and experiments to rationalize the properties of a class of networks based on dicyclopentadiene (DCPD), a polymer with excellent fracture toughness and a high glass transition temperature (Tg), copolymerized with 5-norbornene-2-methanol (NBOH).
Effects of closo-icosahedral periodoborane salts on hypergolic reactions of 70% H2O2 with energetic ionic liquids
Authors: Chinnam Ajay Kumar , Petrutik Natan , Wang Kangcai , Shlomovich Avital , Shamis Olga , Tov Daniel Shem , Sućeska Muhamed , Yan Qi-Long , Dobrovetsky Roman , Gozin Michael
Published: September 2018

A number of energetic ionic liquids (EILs) have been reported as promising hydrazine-replacement fuels for hypergolic rocket propulsion.
Chemical stability of poly(phenylene oxide)-based ionomers in an anion exchange-membrane fuel cell environment
Authors: Willdorf-Cohen Sapir , Mondal Abhishek N. , Dekel Dario R. , Diesendruck Charles E.
Published: September 2018

The chemical stability of polyphenylene oxide grafted with quaternary ammonium salts, ionomers relevant for the development of practical alkaline fuel cells, is studied using hydroxide at different water microsolvation levels.
p-Type BP nanosheet photocatalyst with AQE of 3.9% in the absence of a noble metal cocatalyst: investigation and elucidation of photophysical properties
Authors: Rahman Mohammad Z. , Batmunkh Munkhbayar , Bat-Erdene Munkhjargal , Shapter Joseph G. , Mullins C. Buddie
Published: September 2018

We report microwave-exfoliated p-type few-layer black phosphorous as a photocatalyst for hydrogen production without metal cocatalyst.
3D core–shell MoS2 superspheres composed of oriented nanosheets with quasi molecular superlattices: mimicked embryo formation and Li-storage properties
Authors: Gong Feilong , Peng Lifang , Liu Huanzheng , Zhang Yonghui , Jia Dianzeng , Fang Shaoming , Li Feng , Li Dongming
Published: September 2018

The dynamic composition structural evolution of materials demonstrates a mimicked embryo formation of 3D core–shell MoS2 superspheres for use in lithium ion batteries.
Wetting transition in nanochannels for biomimetic free-blocking on-demand drug transport
Authors: Cheng Yaya , Jiao Xiangyu , Zhao Liang , Liu Yang , Wang Fang , Wen Yongqiang , Zhang Xueji
Published: September 2018

Inspired by aquaporins in nature, herein, a biomimetic free-blocking on-demand drug delivery system is proposed, which is constructed by controlling the wettability of the inner surface of nanochannels on mesoporous silica nanoparticles (MSNs).
Preparation of mussel-inspired injectable hydrogels based on dual-functionalized alginate with improved adhesive, self-healing, and mechanical properties
Authors: Yan Shifeng , Wang Weidong , Li Xing , Ren Jie , Yun Wentao , Zhang Kunxi , Li Guifei , Yin Jingbo
Published: September 2018

A novel mussel-inspired injectable hydrogel based on catechol- and aldehyde-modified alginate was developed, which avoided the introduction of small molecular oxidants and preserved the catechol functional groups.
Effects of varying the lengths of the donor units in π-extended thienothiophene isoindigo-based polymer semiconductors
Authors: Song Eunjoo , Ha Yeon Hee , Kang Boseok , Yun Hui-Jun , Kwon Soon-Ki , Kim Yun-Hi , Cho Kilwon
Published: September 2018

A series of thieno[3,2-b]thiophene isoindigo polymers is synthesized with five different donors that show the versatility of the new acceptor moiety.
Rewritable, light-driven recordings in a full-colour fluorescent polydimethylsiloxane elastomer
Authors: Song Seongkyu , Takezoe Hideo , Jeong Soon Moon
Published: September 2018

A new approach for rewritable, light-driven recordings in PDMS was presented by manipulating the light-induced photobleaching phenomenon.
Impact of monomeric, oligomeric and fibrillar alpha-synuclein on astrocyte reactivity and toxicity to neurons
Authors: Chavarría Cecilia , Rodríguez-Bottero Sebastián , Quijano Celia , Cassina Patricia , Souza José M.
Published: September 2018

Synucleinopathies are a group of neurodegenerative disorders characterized by the presence of aggregated and fibrillar forms of alpha-synuclein (α-syn). Here, we analyze the effect of different species of α-syn, including monomeric, oligomeric and fibrillar forms of the protein, on rat astrocytes. Astrocytes treated with these distinct forms of α-syn showed an increase in long and thin processes and glial fibrillary acidic protein expression, indicating cell activation, high levels of intracellular oxidants and increased expression of cytokines. Moreover, astrocytes incubated with the different species induced hippocampal neuronal death in co-culture, and cytotoxicity was particularly enhanced by exposure to fibrillar α-syn. Further exploration of the mechanisms behind astrocyte activation and cytotoxicity revealed differences between the assessed α-syn species. Only oligomers induced mitochondrial dysfunction in astrocytes and significantly increased extracellular hydrogen peroxide production by these cells. Besides, TNF-α and IL-1β (interleukin 1β) expression presented different kinetics and levels depending on which species induced the response. Our data suggest that α-syn species (monomeric, oligomeric and fibrillar) induce astrocyte activation that can lead to neuronal death. Nevertheless, the tested α-syn species act through different preferential mechanisms and potency. All together these results help to understand the effect of α-syn species on astrocyte function and their potential impact on the pathogenesis of Parkinson's disease and related α-synucleinopathies.
Disordered haematopoiesis and cardiovascular disease: a focus on myelopoiesis
Authors: Dragoljevic Dragana , Westerterp Marit , Veiga Camilla Bertuzzo , Nagareddy Prabhakara , Murphy Andrew J.
Published: September 2018

Cardiovascular (CV) diseases (CVD) are primarily caused by atherosclerotic vascular disease. Atherogenesis is mainly driven by recruitment of leucocytes to the arterial wall, where macrophages contribute to both lipid retention as well as the inflammatory milieu within the vessel wall. Consequently, diseases which present with an enhanced abundance of circulating leucocytes, particularly monocytes, have also been documented to accelerate CVD. A host of metabolic and inflammatory diseases, such as obesity, diabetes, hypercholesteraemia, and rheumatoid arthritis (RA), have been shown to alter myelopoiesis to exacerbate atherosclerosis. Genetic evidence has emerged in humans with the discovery of clonal haematopoiesis of indeterminate potential (CHIP), resulting in a disordered haematopoietic system linked to accelerated atherogenesis. CHIP, caused by somatic mutations in haematopoietic stem and progenitor cells (HSPCs), consequently provide a proliferative advantage over native HSPCs and, in the case of Tet2 loss of function mutation, gives rise to inflammatory plaque macrophages (i.e. enhanced interleukin (IL)-1β production). Together with the recent findings of the CANTOS (Canakinumab Anti-inflammatory Thrombosis Outcomes Study) trial that revealed blocking IL-1β using Canakinumab reduced CV events, these studies collectively have highlighted a pivotal role of IL-1β signalling in a population of people with atherosclerotic CVD. This review will explore how haematopoiesis is altered by risk-factors and inflammatory disorders that promote CVD. Further, we will discuss some of the recent genetic evidence of disordered haematopoiesis in relation to CVD though the association with CHIP and suggest that future studies should explore what initiates HSPC mutations, as well as how current anti-inflammatory agents affect CHIP-driven atherosclerosis.
Hybrid beamforming design for dual‐polarised millimetre wave MIMO systems
Authors: Satyanarayana K. , Ivanescu T. , El‐Hajjar M. , Kuo P.‐H. , Mourad A. , Hanzo L.
Published: September 2018

Millimetre wave (mmWave) communications provide a favourable solution to the ever‐increasing data rate demands because of their abundant bandwidth availability. The conventional wisdom about the mmWave communication channel is that it always exhibits line‐of‐sight (LOS) propagation with directive antennas. However, in mobile communications, mmWave frequencies suffer from frequent LOS blockages and exhibit multipath propagation, which motivates the study and analysis of the polarimetric properties of the mmWave channel. While the exploitation of polarisation is promising, the cross‐polarisation associated with it can be detrimental to the overall performance. Therefore, in this Letter, the authors propose a hybrid precoder design, which mitigates the cross‐polarisation by the joint design of a radio‐frequency beamformer as well as the precoder and combiner used in the baseband. The authors demonstrate through simulations that the proposed design outperforms eigen‐beamforming by 10 dB at a given rate, when considering polarisation.
Adaptive gains of dual level to super‐twisting algorithm for sliding mode design
Authors: Luo Dong , Xiong Xiaogang , Jin Shanghai , Kamal Shyam
Published: September 2018

A gain‐adaption mechanism of a dual level to the super‐twisting algorithm (STA) for adaptive sliding mode design is studied. The proposed dual level method first tunes a third‐order sliding mode observer to exactly estimate the magnitude level of external disturbances, and then adjusts the two gains of STA online simultaneously such that a second‐order sliding mode can take place with small rectifying gains. The gains of the third‐order sliding mode observer are adjusted by exploring the homogeneous property such that only one auxiliary parameter L is needed to be tuned. The magnitude of this parameter L increases until the error between the observer output and actual disturbance disappears. While driving the sliding variable to the sliding mode surface of STA, one gain of the STA automatically converges to an adjacent area of the perturbation magnitude in finite time. The other gain is adjusted by the gain to guarantee the robustness of the STA. This method requires no intervention during adaptation. The usefulness is illustrated by an example of designing an equivalent control‐based sliding mode control with the proposed adaptive STA for a perturbed linear time‐invariant system.
Power maximised and anti‐saturation power conditioning circuit for current transformer harvester on overhead lines
Authors: Qian Zhongnan , Wu Jiande , He Xiangning , Lin Zhengyu
Published: September 2018

The current transformer (CT) harvester is effective and efficient for energy harvesting on overhead lines due to its higher reliability and power density compared to other techniques. However, the current of overhead conductor fluctuates from tens of to thousands of amperes, which brings two challenges for the CT harvester design. First, the startup current, above which the harvester can independently power the monitoring devices, should be as low as possible, so that the battery capacity can be reduced; second, the magnetic core should be ensured unsaturated in high current condition. This study proposes a power conditioning circuit with comprehensive control to maximise the output power and prevent the core from saturation. A prototype that can deliver 22.5 W power with 200 A is designed, and a control strategy based on the finite‐state machine is implemented. Experimental results show that the startup current for 2 W load is about 30 A, and the core power density at 60 A is 45.96 mW/cm3, both of which are markedly improved compared to the reported results of the same condition.
Numerical study of the reconnection process between magnetic cloud and heliospheric current sheet
Authors: Zhang Man , Zhou Yu Fen , Feng Xue Shang , Li Bo , Xiong Ming
Published: September 2018

In this paper, we have used a three-dimensional numerical magnetohydrodynamics model to study the reconnection process between magnetic cloud and heliospheric current sheet. Within a steady-state heliospheric model that gives a reasonable large-scale structure of the solar wind near solar minimum, we injected a spherical plasmoid to mimic a magnetic cloud. When the magnetic cloud moves to the heliospheric current sheet, the dynamic process causes the current sheet to become gradually thinner and the magnetic reconnection begin. The numerical simulation can reproduce the basic characteristics of the magnetic reconnection, such as the correlated/anticorrelated signatures inVandBpassing a reconnection exhaust. Depending on the initial magnetic helicity of the cloud, magnetic reconnection occurs at points along the boundary of the two systems where antiparallel field lines are forced together. We find the magnetic filed and velocity in the MC have a effect on the reconnection rate, and the magnitude of velocity can also effect the beginning time of reconnection. These results are helpful in understanding and identifying the dynamic process occurring between the magnetic cloud and the heliospheric current sheet.
A unique distant submillimeter galaxy with an X-ray-obscured radio-luminous active galactic nucleus
Authors: Shu X. W. , Xue Y. Q. , Liu D. Z. , Wang T. , Han Y. K. , Chang Y. Y. , Liu T. , Huang X. X. , Wang J. X. , Zheng X. Z. , da Cunha E. , Daddi E. , Elbaz D.
Published: September 2018

Aims. We present a multiwavelength study of an atypical submillimeter galaxy, GH500.30, in the GOODS-North field, with the aim to understand its physical properties of stellar and dust emission, as well as the central active galactic nucleus (AGN) activity. Although it is shown that the source is likely an extremely dusty galaxy at high redshift, its exact position of submillimeter emission is unknown.

Methods. We use NOEMA observation at 1.2 mm with subarcsecond resolution to resolve the dust emission, and precisely localize the counterparts at other wavelengths, which allows us to better constrain its stellar and dust spectral energy distribution (SED) as well as redshift. We carry out the new near-infrared (NIR) photometry of GH500.30 observed with HST, and perform panchromatic SED modelling from ultraviolet (UV)/optical to submillimeter. We derive the photometric redshift using both NIR and far-infrared (FIR) SED modeling, and place constraints on the stellar and dust properties such as stellar mass, age, dust attenuation, IR luminosity, and star-formation rate (SFR). The AGN properties are inferred from the X-ray spectral analysis and radio observations, and its contribution to the total IR luminosity is estimated from the broadband SED fittings using MAGPHYS.

Results. With the new NOEMA interferometric imaging, we confirm that the source is a unique dusty galaxy. It has no obvious counterpart in the optical and even NIR images observed with HST at λ ≲ 1.4 μm. Photometric-redshift analyses from both stellar and dust SED suggest it to likely be at z ≳ 4, though a lower redshift at z ≳ 3.1 cannot be fully ruled out (at 90% confidence interval). Explaining its unusual optical-to-NIR properties requires an old stellar population (∼0.67 Gyr), coexisting with a very dusty ongoing starburst component. The latter is contributing to the FIR emission, with its rest-frame UV and optical light being largely obscured along our line of sight. If the observed fluxes at the rest-frame optical/NIR wavelengths were mainly contributed by old stars, a total stellar mass of ∼3.5 × 1011 M⊙ would be obtained. An X-ray spectral analysis suggests that this galaxy harbors a heavily obscured AGN with NH = 3.3+2.0−1.7 × 1023 cm−2 and an intrinsic 2–10 keV luminosity of Lx ∼ 2.6 × 1044 erg s−1, which places this object among distant type 2 quasars. The radio emission of the source is extremely bright, which is an order of magnitude higher than the star-formation-powered emission, making it one of the most distant radio-luminous dusty galaxies.

Conclusions. The combined characteristics of the galaxy suggest that the source appears to have been caught in a rare but critical transition stage in the evolution of submillimeter galaxies, where we are witnessing the birth of a young AGN and possibly the earliest stage of its jet formation and feedback.
Experimental investigation of low-angle dune morphodynamics
Authors: Naqshband Suleyman , Wullems Bas , de Ruijsscher Timo , Hoitink Ton
Published: September 2018

Dunes commonly dominate the bed of sandy rivers and they are of central importance in predicting flow resistance and water levels. In the present study, we show that by using light-weight polystyrene particles as substrate in a laboratory setting, promising morphodynamic similarity is obtained between dunes in shallow flow (flume) and deep flow (field) conditions. In particular, results from our flume experiments show that dune lee-side angles, which are crucial in turbulence production and energy dissipation, better approximate dune lee-side angles observed in natural channels. Furthermore, dune height evolution towards upper stage plane bed observed in the present experimental study, closely follows dune height evolution as observed in world’s large rivers.
Equilibrium scour morphology downstream of rock sills under unsteady flow conditions
Authors: Pagliara Stefano , Palermo Michele
Published: September 2018

The present study aims to analyze the equilibrium scour morphology occurring downstream of rock-made sills with different shapes, under different inflow conditions. Namely, experimental tests were conducted under both steady and unsteady flow conditions. In this last case, the peak discharge was kept the same as the respective base tests performed for steady flow conditions. The scour evolution was carefully monitored, as well as the main characteristic lengths of the scour hole (e.g., maximum scour depth and axial length). The inflow discharge characteristics were varied, i.e., the maximum peak discharge was reached by adopting different hydrographs, in order to test their influence on the equilibrium morphology. Experimental results showed significant similitudes in terms of equilibrium scour morphology between steady and unsteady flow conditions when the hydrograph duration is enough long. The results of the present study can be useful for a correct design of such structure typology in usual applications.
Numerical Modeling of turbidity currents with Ansys CFX and Telemac 3D
Authors: Jodeau Magali , Chamoun Sabine , Feng Jiawei , De Cesare Giovanni , Schleiss Anton J.
Published: September 2018

Turbidity currents may be a relevant lever to manage the accumulation of fine sediments in reservoirs. In this paper, we propose to show how two different numerical codes simulate the propagation of turbidity currents. Telemac 3D and Ansys CFX 17.1 solver were chosen as they are commonly used by many research and engineering teams. The simulations are performed on two configurations. The first case aims at modeling the plunging of a turbidity current. The second model is validated based on an experimental work performed at EPFL. The latter consisted on testing turbidity current venting as a solution to manage reservoir sedimentation. A long and narrow flume was used to simulate the reservoir where a turbidity current was triggered. The advantages and limits of both approaches are discussed in order to supply guidelines for the modeling of turbidity currents in real reservoirs.
Toward an operational approach for the characterization and modelling of fine sediments dynamics in reservoirs
Authors: Peteuil Christophe , Jodeau Magali , De Linares Matthieu , Valette Eric , Alliau Damien , Wirz Carole , Fretaud Thierry , Antoine Germain , Sécher Matthieu
Published: September 2018

Achieving a sustainable management of sediment fluxes in existing or proposed reservoirs is a challenging but essential requirement for dam operators. Such objective is of utmost importance to avoid sedimentation-related consequences. Numerical modelling is of great interest to understand the flow and sediment dynamics in a reservoir, to simulate the long-term evolution of sediment deposits and to evaluate the efficiency of various management strategies. This paper presents recent case studies, which validate the feasibility and relevancy of such technical option. The progresses obtained on essential stages of the numerical modelling of sediments dynamics in reservoirs are particularly emphasized. Concerning the distribution of deposits, a promising field method based on an optimum combination of direct samplings with acoustic measurements and video auscultations is detailed. Feedbacks are then provided concerning an innovative device deployed in the field for a direct measurement of the settling velocity. Issues about the assessment of calibration parameters are also addressed in this communication. Lab experiments performed on deposits sampled in several reservoirs provide practical guidance to evaluate the erosion parameters of sediments. Finally, several examples of sediment dynamics modelling in reservoirs including both cohesive and non-cohesive sediment are presented.
Phenomenological description of scaling laws of sediment transport
Authors: Dey Subhasish , Ali Sk Zeeshan
Published: September 2018

In this paper, we seek the scaling laws of sediment transport under a turbulent flow by applying the phenomenological theory of turbulence. The results show that at the threshold of sediment motion, the densimetric Froude number follows a “(1+σ)/4” scaling law with the relative roughness number (ratio of particle size to flow depth), where σ is the spectral exponent. For the bedload transport, the bedload transport intensity follows a “3/2” and “(1+σ)/4” scaling laws with the transport stage function and the relative roughness, respectively. For the scour in a contracted stream, the dimensionless scour depth follows a “4/(3–σ)”, “– 4/(3–σ)” and “–(1+σ)/(3–σ)” scaling laws with the densimetric Froude number, the channel contraction ratio and the relative roughness, respectively.
Stress balance for a viscous flow with a single rolling particle
Authors: Biegert Edward K. , Vowinckel Bernhard , Hua Leina , Meiburg Eckart
Published: September 2018

One of the most important aspects in hydraulic engineering is to describe flows over mobile porous media in a continuum sense to derive models for sediment transport. This remains a challenging task due to the complex coupling of the particle and the fluid phase. Computational Fluid Dynamics can provide the data needed to understand the coupling of the two phases. To this end, we carry out grain-resolving Direct Numerical Simulations of multiphase flow. The particle phase is introduced by the Immersed Boundary Method and the particle-particle interaction is described by a sophisticated Discrete Element Method. We derive the stress budgets of the fluid and the particle phases separately through a rigorous analysis of the governing equations using the Double Averaging Methodology and the Coarse-Graining Method. As a next step, we perform a simple simulation of a heavy particle exposed to a Poiseuille flow rolling along a wall to understand the physical implications of the fluid-particle coupling. All terms of the stress balances can be computed in a straightforward manner allowing to close the budgets for the two phases separately. However, we encounter problems when attempting to combine the fluid-resolved local stresses with the coarse-grained particle stresses into a single balance for the fluid-particle mixture.
Performance of a groyne in controlling flow, sediment and morphology around a tributary confluence
Authors: Michioku Kohji , Osawa Yuki , Kanda Keiichi
Published: September 2018

In a middle stream reach, irreversible morphological changes are observed such as growth of a huge sandbar in front of the confluence, thalweg migration from the left to right bank, erosion of the main channel and sedimentary deposit on the floodplain. As a countermeasure against such degradation of river morphology, a groyne was constructed beneath the tributary confluence. Performance of a groyne in controlling flood flow, sediment transport and river morphology was investigated by a twodimensional hydrodynamic model. The analysis on twenty years of morphological change indicates that the groyne has an excellent performance in improving quality of river morphology such as reduction of the sandbar development and migration of the thalweg to the original position.
Using high-resolution bedload transport tracer measurements to investigate the characteristics of bedload transport over a large urban flood event
Authors: Berteni Francesca , Plumb Benjamin Douglas , Annable William Kenneth , Grossi Giovanna
Published: September 2018

Channel morphological change is often evaluated by employing sediment transport models since field data during high magnitude low frequency events is rarely available. However, sediment transport rate estimates are heuristic at best to within 1 - 3 orders of magnitude. Mimico Creek is an urban gravel-bed channel in Southern Ontario, Canada that has undergone intensive event-based sediment transport sampling and inter-event bed material particle tracking over a three-year period. A HEC-RAS model was developed of the study reach and calibrated to a series of discharge events where in-situ bedload sampling occurred. Both step-wise discharge and unsteady flow simulations were evaluated to compare sediment transport rates for a range of transport models which included the Meyer-Peter Müller and the Wilcock-Crowe. Calibration curves were developed to estimate sediment discharge in Mimico Creek. The results of the calibrated model were used to calculate the mean travel distance of bed material using the expression for the volumetric rate of bed material transport. Results from the modelling exercise found mean travel distances were similar and in some cases larger than those observed from field measurements, considering both mobile and immobile particles.
Experimental observations on sorting patterns of heterogeneous sediment mixtures in low constrained flows
Authors: Carbonari Costanza , Tanganelli Francesco , Recking Alain , Solari Luca
Published: September 2018

Field and laboratory investigations indicate that gravel bed rivers with bimodal grain size distribution and low lateral confinement, such as in the case of braided or multi-channel rivers, can present simultaneously active channel variations, both in the planimetric and altimetric directions, together with planimetric and vertical sorting. Such aspects were reproduced in new flume experiments considering three flow confinements with characteristic aspect ratios from about 80 to 5. Three long runs of about 60 hours were carried out under constant feeding rate conditions, with a bimodal mixture of natural sediments, a fixed flume slope of 3.18 %, and width imposed by lateral walls from 0.50 m to 0.12 m. We present here the results obtained with the first run, with a width of 0.5 m. We observed fluctuations of bed surface granulometric composition, bed slope, and outlet solid discharge; each of which with its own periodicity. In particular, the rearrangement of the bed surface texture was rapid. Cyclic bed states were observed: a stage of coarsening and aggradation corresponding to low values of outlet solid discharge; a stage of fining and degradation concomitant to high values of transport rate. The other two on-going runs (narrower configurations) aim at investigate the effect of lateral confinement on the morphodynamics of the system.
Bed-load transport: From the beginning into the future
Authors: Hager Willi H.
Published: September 2018

This research addresses bed-load transport in the fluvial environment. Based on the current knowledge, it is first noted that this problem is by far not solved. The eminent questions ask for a large experimental campaign by which the basic issues are solved first, and then expanded to more challenging topics relating to questions not included in the first stage involving uniform water and sediment flows. A number of currently available experimental techniques is mentioned by which a high-quality laboratory experimentation should be feasible. Next, the effects of various fundamental transport parameters should be cleared using both systematic experimentation and data analyses. An improved bed-load transport equation should be established first, by which the current tools are replaced to produce better agreement with prototype data. The role of computational hydraulics is also highlighted, to apply results to natural rivers. Froude similitude should be carefully applied so that the laboratory data can safely be transferred to prototype conditions, if the limitations are respected.
Experimental measurements of flood-induced impact forces on exposed elements
Authors: Sturm Michael , Gems Bernhard , Keller Florian , Mazzorana Bruno , Fuchs Sven , Papathoma-Köhle Maria , Aufleger Markus
Published: September 2018

Torrential flood hazards are a major threat for inhabited alluvial fans. They have the potential to relocate large amounts of sediment from the upper catchments to settlement areas on the alluvial fans where typically distributary processes take place. The approaching water-sediment-mixture impacting on building walls are part of a set of damage-generating mechanisms and may cause severe damages to buildings and infrastructure. It is difficult to predict the magnitude and temporal forces on buildings due to the complex flow patterns and sediment deposition processes around obstacles on the floodplain. Our work focuses on experimental measurements of impact forces of flood events on buildings at a 1:30 scale model. It covers the alluvial fan of the Schnannerbach torrent (Austria) with a set of building structures which are equipped with force measurement devices. The measured impact forces are correlated to the approaching flow heights. Influencing factors on the impacts forces such as surrounding buildings on the floodplain and the presence of openings in the building envelope are also analysed. The influence of different hydraulic flow patterns on the impact forces and regression analyses for an estimation of impact forces are presented.
An Eulerian- Lagrangian numerical method to predict bubbly flows
Authors: Mitrou Elli , Fraga Bruño , Stoesser Thorsten
Published: September 2018

A large-eddy simulation based Eulerian-Lagrangian model is employed to study bubble plumes in an open channel with crossflow. The numerical results are validated with PIV experimental data. Good agreement between simulated and observed velocities is found. The impact of the crossflow on the structure of the plume and the resulting turbulent structures are described.
Lagrangian modeling of bedload movement via the impulse entrainment method
Authors: Wyssmann Micah A. , Papanicolaou A.N. (Thanos)
Published: September 2018

At low shear stresses merely above incipient conditions, the characteristic travel patterns of bedload particles remain difficult to predict due to intermittent movement. At these conditions, particles rest, are entrained into the flow when sufficient momentum transfer from near-bed turbulence occurs, and then come to rest again. The overarching goal of this research is to close the critical gaps related to intermittent movement in order to allow for Lagrangian modeling of bedload at near incipient conditions. Thereby, the specific objectives of the present work are to predict the statistics of (1) the particle resting time, tR, and (2) the magnitude of hydrodynamic momentum transfer (or impulse) during entrainment, Ient. To predict these statistics, we employed the conceptual framework of the impulse entrainment method and predicted impulse statistics by simulating turbulent time series realizations with a generic, regime-based streamwise velocity spectrum. Model validation was carried out by directly comparing simulation results with published experimental impulse and particle entrainment statistics. Model predictions showed that an increase in stress was correlated with a sharp decrease in the average tR and an increase in Ient.
Observation and analysis of long-periodic modes in a confluence with dominant tributary inflow
Authors: Schindfessel Laurent , De Mulder Tom , Loccufier Mia
Published: September 2018

Confluences with dominant tributary inflow are found to exhibit long-periodic alternations of the flow patterns. They are shown to exist both in laboratory experiments and in numerical simulations. By means of a modal decomposition, insight is given into these long-periodic oscillations. The origin of these oscillations is investigated and their significant influence on the secondary flow patterns in the downstream channel is revealed.
Erosion of fine sediments from a rough bed
Authors: Trevisson Michele , Eiff Olivier
Published: September 2018

Gravel beds in river systems represent important aquatic habitats, which may be endangered by the introduction of large amounts of fine sediments. In order to better understand the interaction between fine sediments and coarse immobile beds in sediment supply-limited systems, a series of flume experiments was conducted. The main goal was to determine under what conditions erosion stops. The experiments were performed over a bed of regularly arranged spheres. Plastic particles were taken as sediment and the erosion was investigated under uniform flow conditions for variable bed shear stress conditions just above critical conditions. The system was observed to behave in two different ways: with higher bed shear stress fine sediments were completely washed out, whilst with lower stress the sediment bed reached a stable level just above the equator of the spheres.
A Well-posed Model for Mixed-Sediment River Morphodynamics
Authors: Chavarrías Víctor , Stecca Guglielmo , Labeur Robert Jan
Published: September 2018

The mixed-size character of sediment is a necessary property to ex- plain physical phenomena such as downstream fining or the presence of armor layers. The active layer model was developed to model mixed-size sediment in river morphodynamics. This model assumes that the topmost part of the bed, the active layer, has no vertical stratification and interacts with the flow. The substrate, below the active layer, only interacts with the active layer in case of aggradation or degradation. The active layer model has been used in morphody- namic modelling for more than four decades but under certain conditions it may become mathematically ill-posed. When a model becomes ill-posed, the solu- tion presents unphysical oscillations and its predictive capabilities are lost. We present two alternatives to the active layer model. The first one retains the basic concepts and guarantees well-posedness by means of an additional parameter controlling the celerity of mixed-size sediment processes. The second solution yields a well-posed model by means of considering the sediment transport rate as a stochastic process rather than to adapt instantaneously to the flow. Both models provide reasonable results when compared to measured data from a lab- oratory experiment conducted under conditions in which the active layer model is ill-posed.
Turbulent flow dynamics and mass transport processes in a natural surface storage zone using field data and numerical simulations
Authors: Sandoval Jorge , Escauriaza Cristián , Mignot Emmanuel , Mao Luca
Published: September 2018

In this work, the turbulent flow dynamics and mass transport mechanisms in a natural SSZis analyzed. The study site is a river reach of the Lluta River, located in northern Chile in a high-altitude Andean environment known as the Altiplano (~ 4,000 masl) The large-scale turbulent coherent structures are characterized using field measurements and 3D numerical simulations. The detailed topography was measured through DGPS and digital image processing while the surface velocity field, through the LSPIV technique. Regarding the field data, numerical simulations were performed using a DES turbulence model coupled with a 3D passive scalar transport model for Re = 45,800. The coherent structure dynamics in the shear layer was identified as the main mechanism that drives the mass and momentum transport processes between the SSZ and the main channel. Also, the 2D vortical structures of the mean flow are analyzed within the lateral cavity, since they have a strong influence in mass transport, increasing mean residence times due to their lower velocities and longer exchange timescales. Finally, the performance of two simplified transport models is analyzed to represent the mass transport dynamics at larger scales.
Hydraulic physical model production with Computer Numerically Controlled (CNC) manufacturing techniques
Authors: Henry Pierre-Yves , Aberle Jochen , Navaratnam Christy Ushanth , Ruther Nils
Published: September 2018

Physical models are a well-accepted tool in hydraulic engineering, allowing for the detailed characterisation of flow processes and the validation of structure designs with complex boundary conditions. The methods used to construct physical models typically produce a surface roughness which does not necessarily scale with the surface roughness of the prototype. In this context, this paper discusses novel construction methods allowing a detailed reproduction of roughness elements in scaled models, such as Computer Numerically Controlled (CNC) manufacturing techniques and bed casting techniques. In particular, the present paper details the protocols developed to mill out a correct representation of the complex rock-fractured geometry of a closed channel which was obtained from Terrestrial Laser Scanners. The novelty of this scaled model production is the implementation of optical accesses in a closed (pressurized) hydraulic model, to allow for Particle Image Velocimetry measurements with a minimum impact on the reproduced roughness elements. The effectiveness of this production protocol is discussed in the context of modelling the roughness effects on the flow regime.
An experimental investigation on the flow resistance over a porous gravel-bed surface and its non-porous counterpart
Authors: Navaratnam Christy Ushanth , Aberle Jochen , Qin Jie , Henry Pierre-Yves
Published: September 2018

This paper presents preliminary results from laboratory experiments which were specifically designed to determine the flow resistance over a water-worked gravel-bed and its impermeable counterpart (cast-bed). The technique used to create the cast-bed is introduced, followed by the description of the experimental setup and the procedure to quantify flow resistance over both the water-worked and cast-bed. The influence of the grain orientation on flow resistance was investigated in an additional set of experiments by rotating the cast-bed through 180° in the flume. The main focus of the paper is on the comparison of the bulk flow characteristics for the three different cases for which the beds are characterized not only by the same characteristic grain-diameter but also by an identical surface structure. The obtained results show that the porous, non-porous bed and rotated bed result in different flow resistance and that both bed porosity and grain-orientation have a significant effect on flow resistance.
Estimating uncertainties in hydraulicallymodelled rating curves for discharge time series assessment
Authors: Mansanarez Valentin , Westerberg Ida K. , Lyon Steve W. , Lam Norris
Published: September 2018

Establishing a reliable stage-discharge (SD) rating curve for calculating discharge at a hydrological gauging station normally takes years of data collection. Estimation of high flows is particularly difficult as they occur rarely and are often difficult to gauge in practice. At a minimum, hydraulicallymodelled rating curves could be derived with as few as two concurrent SD and water-surface slope measurements at different flow conditions. This means that a reliable rating curve can, potentially, be developed much faster via hydraulic modelling than using a traditional rating curve approach based on numerous stage-discharge gaugings. In this study, we use an uncertainty framework based on Bayesian inference and hydraulic modelling for developing SD rating curves and estimating their uncertainties. The framework incorporates information from both the hydraulic configuration (bed slope, roughness, vegetation) using hydraulic modelling and the information available in the SD observation data (gaugings). Discharge time series are estimated by propagating stage records through the posterior rating curve results. Here we apply this novel framework to a Swedish hydrometric station, accounting for uncertainties in the gaugings and the parameters of the hydraulic model. The aim of this study was to assess the impact of using only three gaugings for calibrating the hydraulic model on resultant uncertainty estimations within our framework. The results were compared to prior knowledge, discharge measurements and official discharge estimations and showed the potential of hydraulically-modelled rating curves for assessing uncertainty at high and medium flows, while uncertainty at low flows remained high. Uncertainty results estimated using only three gaugings for the studied site were smaller than ±15% for medium and high flows and reduced the prior uncertainty by a factor of ten on average and were estimated with only 3 gaugings.
Integral porosity shallow water model at district scale - Case study in Nice
Authors: Amann Finn , Özgen Ilhan , Abily Morgan , Zhao Jiaheng , Liang Dongfang , Kobayashi Kenichiro , Oishi Satoru , Gourbesville Philippe , Hinkelmann Reinhard
Published: September 2018

After three hours of intense rainfall, the city of Nice was flash flooded on October 3, 2015, resulting in casualties and severe damages in property. This study presents a porous shallow water-model based numerical simulation of the flash flood event in a district of Nice, and compares the results with a high-resolution conventional shallow water model. This contribution aims to discuss practical aspects of applying a porous shallow water model to a real world case. The porous shallow water model is an integral porosity-type shallow water model. It uses unstructured triangular meshes. The conventional shallow water model is a distributed memory parallelized high-performance computing code, that uses a uniform Cartesian grid. The study site is an approximately 5 km2 spanning district of the city of Nice, France. Topography information is available in a 1m resolution and in addition, the available digital elevation model includes inframetric structures such as walls and small bridges. In the presentation of the case study, challenges of the pre-processing step of the integral porosity shallow water model are addressed. Notably, a method to semi-automatically generate “good” triangular meshes using the open-source geoinformation system QGIS and the mesh generator Gmsh is presented. During the post-processing step, the results of the porous model are mapped back onto the high-resolution topography to make the results more meaningful. The agreement between the high-resolution reference solution and the porous model results are poor. A speed up of about 10 to 15 was observed for the present case.