bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppressing charge recombination in small-molecule ternary organic solar cells by modulating donor–acceptor interfacial arrangements
Authors: Wang Zhen , Han Guangchao , Zhu Lingyun , Guo Yuan , Yi Yuanping , Shuai Zhigang , Wei Zhixiang
Published: September 2018

Introducing a proper amount of the third component in ternary blend organic solar cells can result in a significant decrease of docking PC71BM with the central electron-donating unit of electron donors and thus suppress charge recombination.
Mechanistic view of Ru-catalyzed C–H bond activation and functionalization: computational advances
Authors: Shan Chunhui , Zhu Lei , Qu Ling-Bo , Bai Ruopeng , Lan Yu
Published: September 2018

This review summarized recent advances in the mechanistic study of Ru-catalyzed C–H bond functionalization from a theoretical perspective.
3D microfluidic ex vivo culture of organotypic tumor spheroids to model immune checkpoint blockade
Authors: Aref Amir R. , Campisi Marco , Ivanova Elena , Portell Andrew , Larios Dalia , Piel Brandon P. , Mathur Natasha , Zhou Chensheng , Coakley Raven Vlahos , Bartels Alan , Bowden Michaela , Herbert Zach , Hill Sarah , Gilhooley Sean , Carter Jacob , Cañadas Israel , Thai Tran C. , Kitajima Shunsuke , Chiono Valeria , Paweletz Cloud P. , Barbie David A. , Kamm Roger D. , Jenkins Russell W.
Published: September 2018

Microfluidic culture has the potential to revolutionize cancer diagnosis and therapy.
Can molten carbonate be a non-metal catalyst for CO oxidation?
Authors: Tong Jingjing , Lei Xueling , Zhang Peng , Huang Kevin , Mbamalu Godwin , Qin Changyong
Published: September 2018

For the first time, we have examined molten carbonate as a non-metal catalyst for CO oxidation in the temperature range of 300–600 °C.
Ordered SiO2 cavity promoted formation of gold single crystal nanoparticles towards an efficient electrocatalytic application
Authors: Zhao Lili , Zhao Ling , Tian Shu , Ming Hai , Gu Xuefang , Zhou Qun , Zheng Junwei
Published: September 2018

A [111] facet dominated gold single crystal electrode with improved electrocatalytic ability for the oxidation of ethanol and nitrite.
Novel nanocomposite membrane based on Fe3O4@TDI@TiO2–SO3H: hydration, mechanical and DMFC study
Authors: Amoozadeh Ali , Mazdarani Hourieh , Beydaghi Hossein , Tabrizian Elham , Javanbakht Mehran
Published: September 2018

In this paper, a sulfonated poly(ether ether ketone)/SO3H-functionalized magnetic-titania (SPEEK/Fe3O4@TDI@TiO2–SO3H) nanocomposite membrane is synthesized with the aim of reducing methanol permeability as well as improving the proton conductivity and selectivity of pristine polymer to be used instead of Nafion in a direct methanol fuel cell (DMFC).
Codoped Tb3+ and Mn2+ induced tunable emission and energy transfer in Ca19Zn2(PO4)14:Ce3+,Tb3+,Mn2+
Authors: Liang Chao , Fu Yibing , Teng Xiaoming , Liu Kai , You Hongpeng , He Jinhua
Published: September 2018

By tuning the relative content of the doped ions, tunable blue-green emission can be obtained.
Pyridoxal phosphate-dependent reactions in the biosynthesis of natural products
Authors: Du Yi-Ling , Ryan Katherine S.
Published: September 2018

We review reactions catalyzed by pyridoxal phosphate-dependent enzymes, highlighting enzymes reported in the recent natural product biosynthetic literature.
Correction: Stepwise triple-click functionalization of synthetic peptides
Authors: Kovalová Anna , Pohl Radek , Vrabel Milan
Published: September 2018

Correction for ‘Stepwise triple-click functionalization of synthetic peptides’ by Anna Kovalová et al., Org. Biomol. Chem., 2018, 16, 5960–5964.
IQGAP1 binds the Axl receptor kinase and inhibits its signaling
Authors: Gorisse Laëtitia , Li Zhigang , Hedman Andrew C. , Sacks David B.
Published: September 2018

Axl is a tyrosine kinase receptor that is important for hematopoiesis, the innate immune response, platelet aggregation, engulfment of apoptotic cells and cell survival. Binding of growth arrest-specific protein 6 (Gas6) activates Axl signaling, but the mechanism of inactivation of the Axl receptor is poorly understood. In the present study, we show that IQGAP1 modulates Axl signaling. IQGAP1 is a scaffold protein that integrates cell signaling pathways by binding several growth factor receptors and intracellular signaling molecules. Our in vitro analysis revealed a direct interaction between the IQ domain of IQGAP1 and Axl. Analysis by both immunoprecipitation and proximity ligation assays demonstrated an association between Axl and IQGAP1 in cells and this interaction was decreased by Gas6. Unexpectedly, reducing IQGAP1 levels in cells significantly enhanced the ability of Gas6 to stimulate both Axl phosphorylation and activation of Akt. Moreover, IQGAP1 regulates the interaction of Axl with the epidermal growth factor receptor. Our data identify IQGAP1 as a previously undescribed suppressor of Axl and provide insight into regulation of Axl function.
Perturbed block orthogonal matching pursuit
Authors: Cui Yupeng , Xu Wenbo , Tian Yun , Lin Jiaru
Published: September 2018

The block orthogonal matching pursuit (BOMP) algorithm is an efficient method in compressed sensing (CS) for the reconstruction of block‐sparse signals, whose non‐zero entries occur in clusters. However, due to the non‐ideal factors in practice, there exits perturbation in the CS system, which may cause significant performance degradation during reconstruction. In this Letter, a perturbed BOMP algorithm is presented to deal with this problem, which extends BOMP algorithm to the perturbation case. The proposed algorithm performs controlled perturbation on each selected block of support vectors to decrease the orthogonal residual at each iteration. Moreover, the condition of successful reconstruction is derived. Simulation results demonstrate the effectiveness and robustness of the proposed algorithm.
Application of voltage multiplier in 12‐pulse rectifier for sinusoidal input current
Authors: Saravana P.P. , Kalpana R. , Singh B. , Bhuvaneswari G.
Published: September 2018

A DC current injection circuit of a trifurcated autotransformer (TAT)‐based 12‐pulse diode bridge rectifier (DBR) is proposed which can help reduction of harmonics in the AC mains. The circuit at the DC side employs a voltage multiplier (VM) circuits namely voltage doubler, voltage tripler and voltage quadrupler and an interphase transformer which provides the required circulating current. This induced circulating current shapes the input AC line current near to a sine wave. The output of VM circuits is connected across the load and thereby reuses the harmonic energy absorbed by the system. Thus, improves the energy conversion efficiency of the proposed system. The TAT‐based 12‐pulse DBR has the implicit ability to prevent the zero sequence components thus expels the necessity of zero sequence blocking transformer. The proposed configuration is analysed, simulated in MATLAB Simulink and the simulation results are presented, which confirms the improvement in power quality parameters in the input AC line current. Further, the viability of the proposed configuration is verified by experimental results which confirm the suitability of the proposed configuration in AC–DC applications.
Geomorphic identification of physical habitat features in a large, altered river system
Authors: Guertault Lucie , Fox Garey , Brewer Shannon
Published: September 2018

Altered flow regimes in streams can significantly affect ecosystems and disturb ecological processes, leading to species loss and extinction. Many river management projects use stream classification and habitat assessment approaches to design practical solutions to reverse or mitigate adverse effects of flow regime alteration on stream systems. The objective of this study was to develop a methodology to provide a primary identification of physical habitats in an 80-km long segment of the Canadian River in central Oklahoma. The methodology relied on basic geomorphic variables describing the stream and its floodplain that were derived from aerial imagery and Lidar data using Geographic Information Systems. Geostatistical tests were implemented to delineate habitat units. This approach based on high resolution data and did not require in-site inspection provided a relatively refined habitat delineation, consistent with visual observations. Future efforts will focus on validation via field surveys and coupling with hydro-sedimentary modeling to provide a tool for environmental flow decisions.
Quantification of potential recruitment of large woody debris in mountain catchments considering the effects of vegetation on hydraulic and geotechnical bank erosion and shallow landslides
Authors: Gasser Eric , Simon Andrew , Perona Paolo , Dorren Luuk , Hübl Johannes , Schwarz Massimiliano
Published: September 2018

Large woody debris (LWD) exacerbates flood damages near civil structures and in urbanized areas and the awareness of LWD as a risk is becoming more and more relevant. The recruitment of “fresh” large woody debris has been documented to play a significant role of the total amount of wood transported during flood events in mountain catchments. Predominately, LWD recruitment due to hydraulic and geotechnical bank erosion and shallow landslides contribute to high volumes of wood during floods. Quantifying the effects of vegetation on channel and slope processes is extremely complex. This manuscript therefore presents the concepts that are being implemented in a new modelling framework that aims to improve the quantification of vegetation effects on LWD recruitment processes. One of the focuses of the model framework is the implementation of the effect of spatio-temporal distribution of root reinforcement in recruitment processes such as bank erosion and shallow landslides in mountain catchments. Further, spatio-temporal precipitation patterns will be considered using a probabilistic approach to account for the spatio-temporal precipitation variability to estimate a LWD recruitment correction coefficient. Preliminary results are herein presented and discussed in form of a case study in the Swiss Prealps.
Flow structure around an actual willow patch under different depth conditions
Authors: Lee Chanjoo , Kim Donggu , Kim Sungjung , Ji Un , Kim Jihyun , Ko Dongwoo
Published: September 2018

Vegetation is one of the key factors in river management where environmental aspects as well as flood protection should be taken into consideration. Because of this, numerous studies have been done including experiments and hydrodynamic modelling. Because most of experimental studies were made in indoor laboratory flumes with artificial trees, there are still limitations in transfer of their result to actual channels. REC (River Experiment Center) of Korea has been operating three real-scale, nature-like outdoor experimental channels. In a straight channel, several 4x2 m actual willow patches were planted and have been grown last three years for studies on flow vegetation interaction. A set of intensive flow measurement was made around the first upstream willow patch using ADVs together with measurement of vegetation properties. The experiments were made under several different depth conditions simulating snow-melt and flash-flood. Distribution of flow around and through the patch was characterized along with vertical profiles. The results of the experiment enhance understanding on interaction of flow and actual vegetation in a natural channel and may also provide information on flow resistance used for hydrodynamic modelling and validation.
Validation of high-precision effects of a movable riverbed simulation using unmanned aerial vehicles and structure from motion
Authors: Denda Masatoshi
Published: September 2018

For advanced and strategic management of gravel riverbed restoration and stopping of woodland overgrowth, movable riverbed simulations and vegetation dynamic models that can describe a ‘detailed riverbed materials’ transport’ influencing the vegetation dynamics and estimate the creation area of a gravel riverbed are required. As first steps we verified the hypothesis whether high-accuracy observation data using UAV and SfM improve the accuracy of water flow condition and movable riverbed simulation that can describe the riverbed materials’ transport in detail. In the results, High-precision river morphology using UAVs offers the ability to improve the movable riverbed simulation. And these progresses indicated possibilities of UAV and SfM to develop vegetation dynamics model considering the riverbed materials’ transport.
Flow patterns over vegetation patches in the natural channel
Authors: Ryu Yonguk , Kang Joongu , Ji Un , Jung Sanghwa , Jang Changlae , Penning Ellis
Published: September 2018

This study carried out experiments to investigate the effects of vegetation patches of rooted willows on the flow pattern. Stream-scale experiments on vegetated flows were performed for various hydraulic conditions: emergent and submerged conditions of vegetation. Vegetation patches were arranged by alternative bar formation and the flows in vegetated and non-vegetated sections were compared. Three-dimensional flow velocity was measured by ADV (Acoustic Doppler Velocimeter) and ADCP (Acoustic Doppler Current Profiler). Vertical, cross-sectional, and longitudinal velocity distributions were provided for different hydraulic conditions at various points. Flow velocities through the sparse patch were similar to those of non-vegetation area for low flow condition of emergent vegetation. Dense and submerged vegetation produced more complicated and non-uniform flows over the cross-sections of vegetation patches.
Comparison between the circular and square collar in reduction of local scouring around bridge piers
Authors: Khodashenas Saeed Reza , Shariati Hossain , Esmaeeli Kazem
Published: September 2018

In this study operation of two types of circular and square collars has been investigated on a single cylindrical pier. The results showed that using of these two types of collars cause to reduction of scour depth especially under the bed level (elevation). This research showed that the square collar is more effective than circular shape in decreasing of the scour depth). The square and circular collars showed 70% and 50% decrease in rate of scour depth, respectively in compared with simple pier without collar.
Three-dimensional numerical modeling of hydraulics and morphodynamics of the Schwarzenbach reservoir
Authors: Mouris Kilian , Beckers Felix , Haun Stefan
Published: September 2018

In this study the numerical model SSIIM 2 is used to simulate the flow situation and the suspended sediment transport within the Schwarzenbach reservoir in Germany. Hydrodynamic simulations are carried out to assess the influence of wind forces and different discretization schemes on the calculated flow field. A hydraulic plausibility check is performed based on stationary ADCP measurements to assess the performance of the model. Both the consideration of the wind and the plausibility check using an ADCP are hardly used in large reservoirs so far. The simulation results show a complex flow field with two large (re-)circulation zones in the middle of the reservoir, whereby the temporal development of the simulated and measured velocities have comparable characteristics. Moreover, morphodynamic simulations are performed to compute the suspended sediment transport. The results show that the settling behavior of the sediments is mainly influenced by the inflow discharge and the operation level of the reservoir.
Investigation of local scour around tandem piers for different skew-angles
Authors: Memar Sargol , Zounemat-Kermani Mohammad , Beheshti Ali-Asghar , De Cesare Giovanni , Schleiss Anton J.
Published: September 2018

In the present study the effect of the skew-angle of the alignment of tandem piers on local scour depth around them is investigated. The tandem piers were aligned with different skew-angles of θ=0°,30°,45°,60°,90° with respect to the flow direction. The results indicatethat with the increment of the skew-angle, the influence of sheltering effects is decreased. In other word, since the sheltering effect of the upstream pier is declined (which reduces the approach velocity for the downstream pier) the scour depth around downstream pier increases. The results show that the maximum scour depth occurs at both piers for the skew-angle of θ=45°.Furthermore, the best configuration to aligned tandem piers was achieved at the skew-angle of θ=30°.
Scour monitoring on bridge pier – methodology and implementation
Authors: Florens Emma , Chevalier Christophe , Larrarte Frédérique , Schmidt Franziska , Durand Edouard
Published: September 2018

Managing the scour risk of civil structures such as bridge piers, constitutes a major challenge to sustainable development and land use planning. The SSHEAR project aims to build optimized diagnostic, warning and management methods to benefit civil structures. This article is focused on the "Field" approach of the project that develop continuous and real-time scour monitoring. Based on theoretical approach and river database analysis, requirement specifications definition allowed to choose relevant devices to monitor scour. To complete this monitoring system, vibration-based monitoring will also be installed.
Hydropower dams threaten freshwater Chilean fish species: What dams and what species?
Authors: Laborde Anita , Habit Evelyn , Link Oscar
Published: September 2018

Hydropower is experiencing a development boom worldwide. However, at the same time, challenge sustainability, mainly due to synergistic effects of several projects in the species distribution area. What and how hydroelectric projects will affect species, depends on a number of attributes. We analysed Chilean freshwater species distributed over 10 major basins of Central Chile threaten by 1124 plants (12,338 GW) planned in a hotspot of biodiversity. The exposure of the species to the planned hydropower projects was analyzed at the scale of species and as an assemblage. The hazardousness was evaluated by type, according to characteristics of planned hydropower plant: size, dam height and turbine type. Finally, considering species and assemblage exposition the most threaten genera were defined. Project analysed compile 45% of the exploitable potential, with a total of 198 (75.5%) project with capacities < 20MW, and 280 (88.1%) with low head dams (<20 m). 22.6% of the species are not exposed to planned plants, 54.8% are exposed to a small number of plants (<5), and 22.6% are frequently exposed to plants (> 60). The latter species pertain to genera Trichomycterus, Percilia, and Diplomystes, defining a critical fish assemblage that facilitates the management of an important part of the cases (40.4%) through mitigation technologies.
Experimental study of the bed morphology downstream of a sluice gate
Authors: Carvalho Luís , Carvalho Elsa , Aleixo Rui , Lima Maria Manuela C. L.
Published: September 2018

This work describes an experimental study based on a simplified model of a vertical sluice gate installed in a channel with a moving bed of glass spheres with 2 mm diameter. The originated scour cavity and downstream dune were studied. The influence of the apron length and the downstream tailwater depth were also analysed. Imaging techniques provided the tools to this investigation. The data acquisition and processing consisted in acquiring images of the flow and automatically process them to identify the water-sediments interface and the longitudinal profile of sediments’ bed at different instants.
Estimating large woody debris volume and distribution floated and accumulated in reservoir using aerial photographs
Authors: Suzuki Waku , Kobayashi Sohei , Kantoush Sameh , Takemon Yasuhiro , Sumi Tetsuya
Published: September 2018

Large woody debris (LWD) could increase the risk of flooding in the event of heavy rainfall, and fast estimation of the accumulated LWD is crucial for river basin management. We develop a method to automatically detect LWD floating in reservoirs using airborne images, and estimated the total volume of LWD accumulated in a reservoir during a severe flood event in northern Kyushu, Japan, early July 2017. The LWD was successfully extracted from the images based on colour and brightness by using ImageJ. The total volume of the accumulated LWD estimated from images was similar to the LWD volume actually removed from the reservoir by the end of October. Most LWD pieces were concentrated in the upstream-side of the reservoir, and a longitudinal variation in density and length of LWD pieces was also evident.
Field measurements of the attractivity of bypasses for fishfriendly trashrack
Authors: Lemkecher Fatma , David Laurent , Courret Dominique , Chatellier Ludovic
Published: September 2018

Fish-friendly trashracks, combining a low bar-spacing rack and bypasses, are a solution towards the fish downstream migration issue at hydroelectric intakes and rehabilitate the ecological continuity, as aimed by the European Water Framework Directive (2000). To comply to the French Environmental Code, the Hydropower plants (HPPs), located on rivers listed in list 2 according to the article L-214-17, must ensure an adequate sediment transport and free movement of fishes along the river. Each infrastructure has to be managed, and equipped according to the rules set by the administrative body in concertation with the owner or at least the operator. This study concerns inclined trashracks, which have an acute angle starting from the ground, to guide fishes to one of the surface bypass entrances. Well dimensioned bypasses should allow an efficient attraction of the fishes, while limiting the discharge in the bypasses that cause loss for hydraulic operators. In this context, a measurement campaign in a hydropower plant on the Ariège river has been carried out to characterize the velocity profiles at different positions upstream of a 26° angle trashrack with an ADCP and the flow discharge of each of the 3 bypass entrances with flowmeter measurements. The measurements show that the streamwise velocities are quite homogeneous along the rack, without significant acceleration or deceleration, and that the tangential and normal velocities, Vt and Vn, are consistent with their theoretical values. These results tend to validate the angular criteria proposed for inclined rack by Courret et Larinier [6] and studied experimentally by Raynal et al. [4] on a down-scaled model. However, it must be considered that the turbine discharge was low the day of measurement. So, these in situ measurements have to be conducted again, with a turbine discharge closed to its maximum.
Sediment rating and annual cycles of suspended sediment in German upland rivers
Authors: Blöthe Jan , Hillebrand Gudrun , Hoffmann Thomas
Published: September 2018

Sediment flux of lowland rivers is dominated by suspended transport, but data is often sparse and analysis largely relies on rating relationships. However, suspended sediment concentration is by no means constant in both, space and time. Here we analyse the variability of sediment rating curves and the seasonality of suspended sediment concentration in German waterways, as recorded by 10 gauging stations with catchment areas between 2600 - 22000 km2. Our data reveal a distinct break in power-law scaling relationships for all stations, with increased scaling exponents above threshold discharges close to the geometric mean. We attribute this mainly to the activation of sediment sources that resist mobilisation at lower flows. Furthermore, all stations show a counter-clockwise hysteresis effect throughout the year, where summer discharges have a higher sediment load than comparable winter discharges. Though the reasons for this pattern need further investigation, preliminary results show a strong correlation with rainfall erosivity and land-use parameters.
One-Dimensional Modeling of Transport of Coal Ash in a River-Reservoir System
Authors: Altinakar Mustafa S. , Pophet Nuttita , Chao Xiaobo , Marsooli Reza
Published: September 2018

The present study discusses one-dimensional modeling of the coal ash spill into the Dan River in February 2, 2014, using CCHE1D model. The simulations involved unsteady flow hydrodynamics, unsteady non-equilibrium transport of bed material and coal ash in multiple size classes. Discharges of coal ash transport and percentages of coal ash deposited in the mixing layer are presented. The paper presents the investigation of the sensitivity of model results to the rise time and fall time of the triangular hydrographs of pond water and coal ash discharges into the Dan River, the number of size classes used for modeling bed material and coal ash, the mixing layer thicknesses and the nonequilibrium adaptation length.
Phenomenology of meandering of a straight river
Authors: Ali Sk Zeeshan , Dey Subhasish
Published: September 2018

In this study, at first, we analyse the linear stability of a straight river. We find that the natural perturbation modes maintain an equilibrium state by confining themselves to a threshold wavenumber band. The effects of river aspect ratio, Shields number and relative roughness number on the wavenumber band are studied. Then, we present a phenomenological concept to probe the initiation of meandering of a straight river, which is governed by the counter-rotational motion of neighbouring large-scale eddies in succession to create the processes of alternating erosion and deposition of sediment grains of the riverbed. This concept is deemed to have adequately explained by a mathematical framework stemming from the turbulence phenomenology to obtain a quantitative insight. It is revealed that at the initiation of meandering of a river, the longitudinal riverbed slope obeys a universal scaling law with the river width, flow discharge and sediment grain size forming the riverbed. This universal scaling law is validated by the experimental data obtained from the natural and model rivers.
Turbulent kinetic energy flux and budget in a water-worked gravel bed
Authors: Padhi Ellora , Penna Nadia , Gaudio Roberto , Desai V. R. , Dey Subhasish
Published: September 2018

Turbulent flow over a water-worked gravel bed (WGB) was investigated using the double-averaging methodology (DAM). The flow measurements were carried out by the particle image velocimetry (PIV) technique. The double-averaged (DA) turbulent characteristics (DA Turbulent kinetic energy (TKE) components, form-induced TKE components, DA TKE fluxes, form-induced TKE fluxes, DA TKE budget) were analyzed for the WGB. To understand the effect of changed bed topography on the turbulent characteristics, the flow measurements were carried out over a screeded gravel bed (SGB), keeping the flow Froude number same as in case of WGB. Owing to water work, the bed topography of WGB was dissimilar to that of SGB, resulting in higher roughness size for the former than that for the latter. Comparative study of the DA turbulent characteristics of both the beds infers that especially in the near-bed flow zone, the flow parameters of the WGB are attaining higher values than those of the SGB. However, they are almost alike for both the beds in the flow outer layer.
Inferring thermal turbulent structures properties in the wake of an array cylindrical obstacles
Authors: Mulahasan Saad , Stoesser Thorsten
Published: September 2018

In this study a thermal camera was used to inferring the properties of thermal turbulent structures at the water surface of an array of emergent vertical cylindrical obstacles located in staggered fashion at one side of an open channel flow. Three different diameters (D = 1.25 cm, 2.5 cm and 5.0 cm) were tested. A thermal camera SC640 was used to record a series of snapshots of the water surface temperature distribution in the wake of the cylinders at section where the flow was uniform and fully developed. The selection was made after watching a video to locate the most suitable areas for eddies and turbulence development. For the selected location, temperature values were extracted for each sequence at five selection points in the wake region using Matlab software. Time series of temperature for the snapshots of the five selected points in the area of eddy formation were drawn. The energy of the eddies were extracted using Fourier transforms. The results showed successive peaks with a slope of - 5/3. Evaluation of the eddies in the wake of the cylindrical rods showed that the energy of the eddies is small at high frequency and large eddies were observed at low frequencies.
Determining the dynamics of coarse bedload transport using passive indirect monitoring: time-dependent variability at event to inter-annual scales
Authors: Downs Peter W. , Soar Philip J.
Published: September 2018

The dynamics of coarse bedload transport in rivers is governed by multiple hierarchical factors including catchment-scale controls on sediment production, annually variable hydroclimatic driving of segment-scale sediment supply, and reach-scale factors related to the interaction of hydraulic forces with channel morphology. Exploring hydroclimatic drivers can beneficially utilise passive sensors to record coarse bedload transport over extended time periods and in previously unattainable resolution. For the River Avon (Devon, UK), five-minute coarse bedload frequency data collected using seismic impact plates inherently records the instantaneous variability of bedload transport intensity, patterns of event-scale hysteresis and selective path transport, and the influence of inter-event supply variations. Converting a four-year record of impacts into loads via a probabilistic, data-driven model illustrates the combined influence of hydroclimate and sedimentology on bedload at the inter-annual scale. Despite highly variable water years, the results indicate that ‘bar-building flows’ consistently achieve the peak efficiency for coarse bedload transport whereas bankfull flows are relatively ineffective. Further, annual sediment rating curves combine both supply and transport limiting phases. Sediment transport forecasting is thus sensitive to both flow year type and antecedent controls on sediment supply, with implications for advancing sustainable solutions in river management.
Flow and Turbulence driven Water Surface Roughness and Gas Exchange Velocity in Streams
Authors: Noss Christian , Bodmer Pascal , Koca Kaan , Lorke Andreas
Published: September 2018

Gas exchange velocity in streams and rivers controls fluxes of atmospheric gases across the air-water interface and is commonly related to the turbulence at the water side. Similarly, river flow hydraulics influences the water surface roughness, which is frequently used (in terms of surface flow types) for eco- and morphological mapping of spatial variations of hydraulic conditions. We investigated the relationships between gas exchange velocity, water surface roughness and flow hydraulics for different surface flow types in a low-mountain stream. We used the flux chamber-method to estimate exchange velocity, a freely floating sphere (equipped with acceleration sensors) to measure water surface roughness, as well as a field-particle image velocimetry system for flow and turbulence measurements. The results demonstrate that the gas exchange velocity in smooth and rippled flows followed the same universal dependence on turbulent dissipation rates (with an empirical scaling coefficient at the upper limit) as observed in wind-driven systems. More rough flows were anisotropic and gas exchange velocity was stronger related to vertical components of turbulence parameters. We further explored the potential of using surface flow type evaluations and water surface roughness measurements for estimating gas exchange velocities at the reach scale and beyond.
Flow Bifurcation at a Longitudinal Training Dam: Effects on Local Morphology
Authors: de Ruijsscher Timo , Naqshband Suleyman , Hoitink Ton
Published: September 2018

Longitudinal training dams (LTDs) have been built over a length of 10 km in the Dutch River Waal as an alternative to groyne fields, splitting the river in a fairway and a bank-connected side channel in the inner bend. Here, we study the physical mechanisms governing the three-dimensional flow and its effect on local morphology at the flow divide using a mobile bed physical model of an LTD, centred around a side channel intake. In line with previous experiments, polystyrene granules are used as a lightweight sediment that allows to achieve dynamic similarity between the model and the prototype. An Acoustic Doppler Velocimetry (ADV) profiler is used to monitor the flow characteristics, whereas a line laser scanner set-up is used to measure the morphological imprint of the flow near the bifurcation point. To study the dependence of the results on the sill height at the side channel intake, different forms and heights of the sill are used. First results show striking similarities with measurements from the field pilot in the Waal River, as well as larger sedimentation in the side channel for a uniform low sill compared to a downstream increasing sill height.
Stochastic bedload transport in mountain streams
Authors: Ancey Christophe , Bohorquez Patricio
Published: September 2018

Describing bedload transport as a stochastic process is an idea that emerged in the 1930s with the pioneering work of Einstein. For a long time, the stochastic approach attracted marginal attention, but the situation has radically changed over the last decade with the recent advances in the theory of bedload transport. In parallel, the implementation of bedload monitoring techniques at high temporal resolution has produced a wealth of interesting results showing, among other things, that classic empirical bedload transport equations do not capture neither the mean behavior of sediment transport rates qs nor its order of magnitude, especially at low sediment transport rates (a case that is most frequent in mountain streams). We have developed a stochastic model, which takes inspiration from population dynamics and provides a stochastic partial differential equation for the number of moving particles. Taking the ensemble average leads to a fairly simple advection diffusion equation for particle activity (i.e., the number of moving particles per unit streambed area). The model has a number of unique features. For instance, it yields the probability distribution of the bedload transport rate and predicts bedform formation for a wide range of Froude numbers.
The 3D Numerical Study on Flow and Sediment Properties of a River with Grouped Spur Dikes
Authors: Han Xun , Lin Pengzhi , Parker Gary
Published: September 2018

A 3D numerical model named NEWTANK is employed to investigate the flow motion and sediment transport in grouped spur dikes system. This model is based on the Navier-Stokes equations, adopting the Volume of Fluid (VOF) method to track the free surface motion, while the solid is described by using the Porous Media Method (PMM). The Large Eddy Simulation (LES) is applied to capture turbulence. In sediment calculation parts, the suspended load and bedload are treated separately but combined together to update bed variation eventually. The finite difference form and Two-step Projection Method are employed in the process of discretizing the governing equation. Several carefully selected flume experiments are introduced to verify this model's reliability before its application on the simulation of grouped spur dike case, and detailed flow characteristics and sediment properties are analyzed afterwards.
Flow Structure in a Shallow Mixing Layer Developing over 2-D Dunes
Authors: Kirkil Gokhan
Published: September 2018

A high resolution Detached Eddy Simulation (DES) are used to characterize the evolution of a shallow mixing layer developing between two parallel streams in a long open channel over two-dimensional (2D) dunes. The study discusses the vertical non-uniformity in the mixing layer and provides a quantitative characterization of the growth of the large-scale quasi 2D coherent structures with the distance from the splitter plate. The presence of large-scale roughness elements in the form of an array of two-dimensional dunes with a maximum height of 0.25D (D is the channel depth) induces a very rapid and larger shift of the centerline of the mixing layer due to the increased influence of the bottom roughness. Results show that in streamwise sections situated after 100D (D is the channel depth) from the splitter plate, the width of the mixing layer close to the free surface stays constant. The tilting of the mixing layer interface toward the low speed stream is observed as the free surface is approached in all vertical sections.
Experimental and numerical analyses on the capacity and the control management of a large flood retention basin situated at the Inn River in Tyrol
Authors: Lindermuth Adrian , Gems Bernhard , Kampel Irina , Waldhör Christoph , Walder Stefan , Aufleger Markus
Published: September 2018

The consideration of recent extreme events in flood statistics implies an increase of design flood peaks and discharge loads. With the focus on the 75 km long Tyrolean Inn River reach downstream the regional capital city Innsbruck, the harmonization of the 100-year flood peak and comprehensive 2d-hydrodynamic modelling simulations indicate the need for an extension of the existing flood protection measures. Lateral protection and object protection measures represent the only feasible option due to the confined areal conditions. However, an increase of the channel capacities would worsen the situation for downstream areas demonstrably. In order to counter this impact, it is planned to build several large controlled flood retention basins situated along the Inn River at the valley floor between Innsbruck and the border to Germany. The retention basin “Voldöpp” as one of these flood polders features a maximum capacity of 1.7 million m³ and a maximum design water depth of 3.6 m. According to current planning the inlet structure consists of four uniform weir fields with two gates each. Aims of the presented experimental and numerical analyses are the investigation of the flow characteristics in close range of the inlet structure, the weir capacity and a possible weir control management. Hydraulic model tests are accomplished at the scale 1:35 according Froude similarity and numerical modelling is done with the software FLOW-3D. Preliminary modelling results confirmed the functionality of the inlet structure and pointed out the need of further tests concerning the potential impacts of intense sediment transport and woody debris.
A Study on Evacuation Safety at Inundated Stairs by using Real-scale Hydraulic Model Experiment
Authors: Kim Myounghwan , Lee Du Han , Kim Ji-sung , Eom Jung Hyun
Published: September 2018

In recent years, sudden and local downpours in Korea have become more frequent. These rainfall patterns increase load on drainage system and reduce ability to exclude inland water, leading to flooding. If such rainfall patterns lead to flash floods especially in dense urban areas, sudden submergence of underground spaces by floods can be a fatal threat to life. Therefore, it is very important to secure evacuation routes in case of inundated underground spaces. In this study, we tried to determine evacuation safety by understanding hydraulic characteristics of inundated stairs that could become evacuation routes in underground spaces. For this purpose, water depth and volume flow rate were measured at each point of inundated stairs, and data obtained from results were used to evaluate evacuation safety at each step.
Balancing river restoration measures around a river bifurcation: A case study from the Netherlands
Authors: Schielen Ralph , Voortman Bert , Driessen Tjeerd
Published: September 2018

The Rhine River in the Netherlands still has some characteristics of a delta, although the river is extremely engineered and confined between dikes. An important characteristic are the bifurcation points where the river bifurcates into different branches. The discharge partitioning at the bifurcates is predefined, as this is an important element for the protection of the downstream branches. Adjustable control structures in the vicinity of the bifurcation point facilitate this setting. In order to mitigate higher discharges due to climate change, measures in the floodplains to reduce flood levels are projected. In the planning process, it is important to maintain the discharge partitioning and to guarantee a setting of the control structure such that some control space is left. This can be done by balancing measures. A measure which lowers the flood levels on one branch, should be balanced by another measure on the other branch in order to maintain the correct settings. This requires a careful planning process and careful considerations between flood level lowering and settings of the control structures.
Flood Risk Mapping for Emergency Management by Applying Grid-based Model
Authors: Han Kun Yeun , Park Jun Hyung , Choi Hehun
Published: September 2018

A grid-based numerical model is developed by improving the diffusion hydrodynamic model that can accurately reflect LiDAR data and enable an efficient hydraulic analysis by linking river and drainage networks. In order to verify 2D model, recent flood events, which occurred in the Gimcheon area during Typhoon Rusa on 2002 is considered. For the estimations of flood disaster vulnerability index, population density, household income, access to evacuation route/time, and shelter information are included. The flood hazard map considering flood depth, velocity, flood arrival time is combined with the flood vulnerability information to derive a flood risk map. The flood risk map presented in this study can provide useful information for the preparation of evacuation plan through accurate flood hazard results and disaster vulnerability index.
Improvement of anisotropic porosity models with a merging technique
Authors: Bruwier Martin , Archambeau Pierre , Erpicum Sébastien , Pirotton Michel , Dewals Benjamin
Published: September 2018

Anisotropic porosity shallow-water models are used to take into account detailed topographic information through porosity parameters multiplying the various terms of the shallow-water equations. A storage porosity is assigned to each cell to reflect the void fraction in the cell and a conveyance porosity is used at each edge to reproduce the impact of subgrid obstacles on the flux terms. To guaranty the numerical stability, the time step depends on the value of the porosity parameters. This may hamper severely the computational efficiency in the presence of cells with low values of storage porosity. Cartesian grids are particularly sensitive to such a case since the meshing stems directly from the choice of the grid size. In this paper, this problem is addressed by using an original merging technique consisting in merging cells with a storage porosity lower than a threshold value with neighbouring cells. The model was tested for modelling a prismatic channel with different orientations between the Cartesian computational grid and the channel direction. The results show that the standard anisotropic porosity model (without merging) improves the reproduction of the flow characteristics; but at the cost of a significantly higher computational time. In contrast, the computational time is drastically reduced and the accuracy preserved when the merging technique is used with the porosity model.
Recalculation of historical streamflow series. Impact assessment and valorization
Authors: Belleville Arnaud , Hauet Alexandre , Tacnet Amélie , Sevrez Damien
Published: September 2018

Rating curves used to calculate discharge from water level must be extrapolated beyond the range of measured discharges, due to the difficulty of measuring flood discharge. This induces large uncertainties and the flood discharge series can be unreliable. This paper presents a methodology to update and correct historical flood flows, so as to propose homogeneous and less biased data. The benefit of using hydraulic modeling is discussed. This methodology is applied to a large sample of hydrometric stations of the EDF (Electricité De France) network, and the impact on peak flows deviations is analyzed.
Flood mitigation through riparian detention in response to climate variability - a case study in Taiwan
Authors: Lee Kwan Tun , Huang Pin-Chun
Published: September 2018

Considering that urban areas may suffer more substantial losses than riparian farmlands during floods, diverting floodwater into riparian areas for temporal detention is expected to mitigate flood damage in downstream urban areas. In this study, an assessment has been conducted to evaluate the effect of flood mitigation through riparian detention in response to climate variability in the Tou-Chien Basin of Taiwan. A couple 1D-2D model was used to simulate the flood wave transporting in the main stream and the overbank flow inundating into the urban areas. Based on the numerical simulation results, flooding extent and inundated water depth corresponding to different return periods with current flood prevention infrastructures were detailed investigated. Various riparian detention strategies were proposed to alleviate severe losses in the downstream urban areas of the Tou-Chien Basin.
Hydrograph estimation at upstream ungauged sections on the Secchia River (Italy) by means of a parallel Bayesian inverse methodology
Authors: Ferrari Alessia , D'Oria Marco , Vacondio Renato , Mignosa Paolo , Tanda Maria Giovanna
Published: September 2018

In this work, we present a reverse flow routing procedure, which allows estimating discharge hydrographs at upstream ungauged stations by means of information available at downstream monitored sites. The reverse routing problem is solved adopting a Bayesian Geostatistical Approach (BGA). In order to capture the complex hydrodynamic field typical of many real cases of rivers including large floodable areas, meanwhile overcoming the computational time limitations, we adopted as forward model a selfdeveloped 2D-SWE parallel numerical model (PARFLOOD) that allows achieving ratio of physical to computational time of about 500-1000. To exploit the computational capabilities of modern GPU cluster, a parallel procedure to estimate the Jacobian matrix required by the BGA approach has been implemented. The inflow hydrograph in a river reach with several meanders and floodplains has been estimated in “only” 13 hours using a HPC cluster with 10 P100 Nvidia GPUs.
Assessment of hydropower resources in Tanzania. A review article
Authors: Mdee Ombeni J. , Nielsen Torbjorn K. , Kimambo Cuthbert Z. , Kihedu Joseph
Published: September 2018

The hydropower resources have become an attractive means of generating electricity to the off-grid network, especially in rural areas. This article assesses the small, mini and large hydropower resources and identified to reach 5.3 GW for electricity generation in Tanzania. The technology development discussed comprises of hydro turbine manufacturers, classification and turbine selection. The barriers presented include the presence of sediment in the hydropower reservoirs, financial viability, policy and regulatory issues related to hydropower development. This reviewed article serves the investors and policymakers to understand the status of hydropower resources in Tanzania.
Am Tod Maß nehmen fürs (Weiter-)Leben
Authors: Maurer Franziska
Published: September 2018

Der Tod eines Kindes an seinem Lebensanfang erschüttert und verunsichert die werdenden Eltern, ihr ganzes Umfeld und die involvierten Fachleute. Ohnmachtsgefühle angesichts der Ausweglosigkeit sind bei vielen Beteiligten zu beobachten. Wie gelingt es, Eltern in dieser Situation sensibel zu begleiten und als Hebamme selbst handlungsfähig zu bleiben? Die Autorin reflektiert diese Frage auf Basis ihres Erfahrungswissens und fundierter Studien.
Typ-2-Diabetes im Alter
Authors: Müller-Wieland Dirk
Published: September 2018

Im Alter wird die Prognose des Typ-2-Diabetes nicht so sehr durch die Qualität der Stoffwechseleinstellung bestimmt, sondern vielmehr durch die verbleibende Lebenszeit und vor allem durch die Funktionalität des Patienten. Wichtig ist es daher, Komorbiditäten zu berücksichtigen und kurzfristige Komplikationen (z. B. eine Hypoglykämie) strikt zu vermeiden. Die Diabetestherapie sollte primär die persönli-chen Lebensziele des Patienten im Fokus haben, seine Lebensqualität sowie den Erhalt der funktionellen Unabhängigkeit.