Channel Width Research Articles

GraphFlood 1.0: an efficient algorithm to approximate 2D hydrodynamics for landscape evolution models

Abstract. Computing hydrological fluxes at the Earth's surface is crucial for landscape evolution models, topographic analysis, and geographic information systems. However, existing formalisms, like single or multiple flow algorithms, often rely on ad hoc rules based on local topographic slope and drainage area, neglecting the physics of water flow. While more physics-oriented solutions offer accuracy (e.g. shallow-water equations), their computational costs limit their use in terms of spatial and temporal scales. In this contribution, we introduce GraphFlood, a novel and efficient iterative method for computing river depth and water discharge in 2D with a digital elevation model (DEM). Leveraging the directed acyclic graph structure of surface water flow, GraphFlood iteratively solves the 2D shallow-water equations. This algorithm aims to find the correct hydraulic surface by balancing discharge input and output over the topography. At each iteration, we employ fast-graph-theory algorithms to calculate flow accumulation on the hydraulic surface, approximating discharge input. Discharge output is then computed using the Manning flow resistance equation, similar to the River.lab model (Davy and Lague, 2009). The divergence of discharges iteratively increments flow depth until reaching a stationary state. This algorithm can also solve for flood wave propagation by approximating the input discharge function of the immediate upstream neighbours. We validate water depths obtained with the stationary solution against analytical solutions for rectangular channels and the River.lab and CAESAR-Lisflood models for natural DEMs. GraphFlood demonstrates significant computational advantages over previous hydrodynamic models, an with approximately 10-fold speed-up compared to the River.lab model (Davy and Lague, 2009). Additionally, its computational time scales slightly more than linearly with the number of cells, making it suitable for large DEMs exceeding 106–108 cells. We demonstrate the versatility of GraphFlood by integrating realistic hydrology into various topographic and morphometric analyses, including channel width measurement, inundation pattern delineation, floodplain delineation, and the classification of hillslope, colluvial, and fluvial domains. Furthermore, we discuss its integration potential in landscape evolution models, highlighting its simplicity of implementation and computational efficiency.

Solvent-mediated analgesia via the suppression of water permeation through TRPV1 ion channels.

Activation of the ion channel transient receptor potential vanilloid 1 (TRPV1), which is integral to pain perception, leads to an expansion of channel width, facilitating the passage of cations and large organic molecules. However, the permeability of TRPV1 channels to water remains uncertain, owing to a lack of suitable tools to study water dynamics. Here, using upconversion nanophosphors to discriminate between H2O and D2O, by monitoring water permeability across activated TRPV1 at the single-cell and single-molecule levels, and by combining single-channel current measurements with molecular dynamics simulations, we show that water molecules flow through TRPV1 and reveal a direct connection between water migration, cation flow and TRPV1 functionality. We also show in mouse models of acute or chronic inflammatory pain that the administration of deuterated water suppresses TRPV1 activity, interrupts the transmission of pain signals and mitigates pain without impacting other neurological responses. Solvent-mediated analgesia may inspire alternative options for pain management.

Optimization of Ecological Dispatch and Hydrodynamic Improvements in Tidal River Channels Using SWMM Modeling: A Case Study of the Longjin Yangqi Area in Kurama Mountain

Being tidal-sensitive, the river channel in the Longjin Yangqi area of Cangshan, Fuzhou City, is challenged further because of rapid urbanization. Thus, resultant remediation efforts are crucial. This study aims analyzes hydrodynamic characteristics of the area and, secondly, proposes an ecological dispatch solution with evaluation of its effectiveness through the Storm Water Management Model (SWMM). The chief tasks cover imitating rainfall runoff, optimizing sluice gate activities, reorganizing pump management, and reshaping river morphology to bolster flood control and water quality. Improvements were shown through ecological dispatch strategies, which suggested increasing the channel width for the river and deepening the riverbed, thereby increasing the flood duration, lowering water levels, and less frequent flood occurrences. Optimizing sluice gate settings improved efficiency in the regulation of water flow and reduced scour or siltation problems. Various adjustments to pumping operations scattered over various times were based on live-data analysis, therefore enhancing water flow and the self-purification capacity of the water body. The SWMM was directly applied in this tidal river for urban water resource management with data processing from over 100,000 points in simulations. Wherever needed, changes to model parameters were made to improve its capability and enhance its appropriate use in future urban settings. As a whole, this study presents a plan for sustainable water resource management paired with environmental conditions for the benefit of over 500,000 urban residents in the Longjin Yangqi area.

Fused Deposition Modeling of Chemically Resistant Microfluidic Chips in Polyvinylidene Fluoride.

Fused deposition modeling (FDM) is well suited for microfluidic prototyping due to its low investment cost and a wide range of accessible materials. Nevertheless, most commercial FDM materials exhibit low chemical and thermal stability. This reduces the scope of applications and limits their use in research and development, especially for on-chip chemical synthesis. In this paper, we present FDM fabrication of microfluidic chips with polyvinylidene fluoride (PVDF) for applications that require high thermal or chemical resistance. Embedded microchannels with a minimum channel width and heights of ~200 µm × 200 µm were fabricated, and the resistance against common solvents was analyzed. A procedure was developed to increase the optical transmission to result in translucent components by printing on glass. Chips for fluid mixing were printed, as well as microreactors that were packed with a catalytically active phase and used for acetal deprotection with a conversion of more than 99%. By expanding the use of fluorinated polymers to FDM printing, previously challenging microfluidic applications will be conducted with ease at the lab scale.

Wifi 7: Advancements, Applications and Future Prospects

The goal of Wi-Fi 7, a major advancement in wireless networking technology, is to satisfy the increasing demand for faster data speeds, reduced latency, and more spectrum economy. Building on the success of Wi-Fi 6 and 6E. this next generation offers previously unheard-of speeds of up to 30 Gbps and improved network stability with innovations like 320 MHz channel width, 4096-QAM (Quadrature Amplitude Modulation), and Multi-Link Operation (MLO). Virtual/augmented reality (VR/AR). high-definition media streaming, sophisticated loT ecosystems, and industrial automation arc just a few of the many uses that Wi-Fi 7 is anticipated to enable. Wi-Fi 7 is expected to serve new use cases that require dependable, fast wireless connections, such smart cities, real-time telemedicine, and driverless cars, thanks to its extremely low latency and smooth multi-connection management

Particle spacing and stability of initially staggered deformable particle trains migrating in a channel

Abstract We investigated the inertial migration of deformable particles in a two-dimensional channel flow. This study analyzes the effects of the channel Reynolds number ($Re$), channel blockage ratio ($k$), particle number ($N_p$) and reduced bending modulus ($E_b$) on the formation of staggered particle trains. The results show that the stable normalized distance $d_{p_{eq}} / H$ between two staggered particles is influenced by $Re$, $k$ and $E_b$, where $H$ is the channel width. As $k$ increases or $E_b$ decreases, $d_{p_{eq}} / H$ decreases. The value of $d_{p_{eq}} / H$ initially increases and then decreases with the increase of $Re$; when $E_b$ is large and $k$ is small, $d_{p_{eq}} / H$ continuously increases with increasing $Re$. With the increase of $N_p$, the closely arranged staggered particle trains evolve into five distinct migration Regimes. We explain the conditions for the formation of each Regime and explore the mechanisms of their interconversion. The findings of this study contribute to a better understanding of the self-organization process of deformable particles in channel flow.

Channel width modulates the permeability of DNA origami-based nuclear pore mimics.

Nucleoporins (nups) in the nuclear pore complex (NPC) form a selective barrier that suppresses the diffusion of most macromolecules while enabling rapid transport of nuclear transport receptor (NTR)-bound cargos. Recent studies have shown that the NPC may dilate and constrict, but how altering the NPC diameter affects its selective barrier properties remains unclear. Here, we build DNA nanopores with programmable diameters and nup arrangements to model the constricted and dilated NPCs. We find that Nup62 proteins form a dynamic cross-channel barrier impermeable to hepatitis B virus (HBV) capsids when grafted inside 60-nm-wide nanopores but not in 79-nm pores, where Nup62 cluster locally. Furthermore, importin-β1 substantially changes the dynamics of Nup62 assemblies and facilitates the passage of HBV capsids through the 60-nm NPC mimics containing Nup62 and Nup153. Our study shows that transport channel width is critical to the permeability of nup barriers and underscores NTRs' role in dynamically remodeling nup assemblies and mediating the nuclear entry of viruses.

Seasonally stable wetted width elucidates freshwater mussel species richness and endangered species presence: implications for T&E management programs and stream restoration design

Centuries of beaver extirpation, deforestation, and other anthropogenic impacts have disconnected North American rivers from their floodplains and concentrated more hydraulic energy within their channels, degrading aquatic habitat and making the streambed more prone to erosion. Rivers naturally adjust via systematic downcutting, bank erosion, channel widening, bar building, and the gradual recovery of geomorphic equilibrium with well‐connected benches that dissipate hydraulic energy and restore a more natural streambed disturbance regime. The life histories of two endangered freshwater mussels, the fanshell (Cyprogenia stegaria) and snuffbox (Epioblasma triquetra), suggest they have evolved to and depend on the natural disturbance regime. Young juveniles excyst from their host fish in early summer, burrow into the top few millimeters of the streambed, and then need ca. 3 months of streambed stability prior to growing large enough to be less vulnerable to streambed mobilization. We propose a conceptual model that suggests a potential prerequisite to supporting fanshell and snuffbox populations is a geomorphically recovering (i.e. at least one stable bank and a wide enough channel corridor for at least partially vegetated bars/benches) or recovered (i.e. stable banks and vegetated benches) channel and floodplain corridor that sufficiently dissipates its hydraulic energy to maintain seasonal streambed stability during typical (non‐hurricane) summer/autumns. To explore this conceptual model, we conducted mussel and geomorphic surveys in a reach of the Rolling Fork River that spanned a range of channel conditions from chronically failing streambanks to a geomorphically recovered channel with wide, vegetated benches. Our analyses documented increasing mussel species richness, including the presence of the endangered fanshell or snuffbox, with increasing width of seasonally stable streambed habitat.

The Channel Migration of Inland Waterway Channels in Ilaje, Ondo State, Nigeria

The channel migration or shifting of navigable river channels have been an issue of major concern, as their effects on the transport environment, channel corridors, the manoeuvrability of vessels transiting these channels and vessels navigation amongst other factors result to inefficiency in inland transport in the riverine region of Ilaje, Nigeria. Most navigational and operational challenges have been attributable to alterations in the waterway channel due to aggradation and degradation processes in the river regime. The study’s goal is to explore channel migration along the Igbokoda-Ayetoro waterway with a view to provide mitigation methods to address potential difficulties along the waterway channel and in the adjoining environment. The objectives of the study include gathering satellite imagery of the study area between 1972 and 2022; assessing the morphological planforms of the study river channel, and assessing the river channel’s effective width using the segment-transect method. The study considered channel width, depth and alignment as indicators to be carefully evaluated to ensure safe, sustainable and efficient inland navigation measures. To ascertain the shapes and forms of the channel during the study period, geospatial and computer-aided techniques were used. Channel widths were extracted using the Segment-Transect method at 100-meter intervals. 50 year and 100-year estimate of the extent of channel/banklines shifting were determined. According to the study, there are changes in the channel’s width, depth and planform (alignment) that make the waterway indeterminate and unsuitable for vessels transiting on two-way manoeuvrability lanes. Hence, the study recommended the sustainable mitigation strategies to tackle the potential challenges pose by channel migration and reduce its impact on the vessel manoeuvrability, navigation and the adjoining environment.

Investigation of roll forming process and quality control factors for metal bipolar plates

Metal bipolar plates (BPPs) are crucial components of proton exchange membrane fuel cells (PEMFCs), with the quality of their formation affects the power generation efficiency and lifespan of the fuel cells. The predominant manufacturing method, stamping, often results in localized excessive stretching of metal BPPs, thereby limiting the depth of the flow channels. Roll forming, dominated by bending deformation, is a forming process that ensures uniform thinning and greater depth of BPPs. The multi-directional flow channel roll forming model for BPPs is constructed in this paper for the first time, the characteristics of the roll forming process is investigated. Effects of process parameters on the forming results are discussed. The investigation indicates that during the roll forming process, the channel ports and corners are critical areas where defects are most likely to occur. The average filling ratio of the longitudinal flow channels is 5.6% higher than that of the transverse flow channels. The plastic strain in the longitudinal flow channels is about 36% higher than in the transverse ones, which making the form is more difficult to form, but the thickness is more uniform. Increasing the diameter of the rollers can enhance the filling ratio and flatness, but it will exacerbate thinning at the corners of the flow channels. When the ratio of the flow channel width to the rib width is close to 1, the filling ratio of the BPP is higher, with less thinning, resulting in a better forming result. As the depth of the flow channel increases, resulting in a thinner BPP, when depth-to-width ratio exceeding 0.6 is more likely to lead to failure. Increasing the speed of roll forming can lead to a greater thinning of the BPP and may even cause it to crack. The thinner the sheet metal is, the higher the filling ratio of the BPP and the more uniform its thickness. Those results can provide technical references for the structural design and forming process optimization of BPPs.

Machine learning-based prediction of scour depth evolution around spur dikes

ABSTRACT Spur dikes are pivotal elements in river training, serving to mitigate the dynamic alterations induced by river degradation and aggradation. Traditionally, scour prediction models have relied on regression techniques, but the advent of soft computing and machine learning has offered opportunities for enhanced accuracy. This study focuses on the development of hybrid machine-learning models, including eXtreme Gradient Boosting (XGBoost), random forest (RF), convolutional neural network–long short-term memory, and artificial neural network, optimized using genetic algorithms to predict both temporal scour depth variation and maximum scour depth around the initial spur dike in a series. The analysis reveals strong associations between scour depth and various parameters such as non-dimensional time, spacing, channel width, time-averaged velocity, and densimetric Froude number. The models are established through an iterative process involving four predictor combinations. Results demonstrate XGBoost as the top-performing model, consistently exhibiting superior performance with R2 of 0.99, root mean square error (RMSE) of 0.012, and mean absolute error of 0.008 during training, and R2 of 0.96, RMSE of 0.044, and Kling–Gupta efficiency of 0.98 during testing for predicting temporal scour depth. For non-dimensional maximum scour depth, it reached R2 of 0.99 and RMSE of 0.005 in training, with R2 > 0.91 across all combinations during testing. Although RF showcases commendable accuracy, it slightly lags in precision compared to XGBoost.

Device to circuit level implementation of JL-NSFET for DC/analog/RF applications at sub-5nm technology node: design optimization and temperature analysis

Abstract This manuscript introduces, for the first time, a novel approach that incorporates a comprehensive analysis of sheet variations (1–5) and every individual sheet wise temperature variation, and as well as an investigation of various GS high-k gate dielectrics in Junction-less (JL) Nanosheet FET (JL-NSFET). The study starting from device level (Digital/Analog/Radio Frequency) to circuit (CMOS Inverter and ring oscillator) as a whole package is investigated through well calibrated TCAD simulation and the results portrayed. NSFETs are the ultimate choice for integrated circuits (ICs) at sub-5 nm technology node. The notion of this paper is to design and optimization of NSFET with GS high-k gate dielectrics (Al2O3, HfO2, ZrO2 and TiO2) Initially. The switching/analog and RF metric revels that HfO2 is superior in terms SS, switching applications and more compactable with CMOS process. Further, adding number of sheets and temperature variation has been done later. As number of sheets increases, the effective channel width increases, electric field distribution takes place evenly and enhanced gate control owing to improved I O N , I O N / I O F F r a t i o , SS and DIBL. However, increasing the number of vertical channel layers (sheets) more than 2 results into diminished analog/RF performance of JL-NSFET owing to increased parasitic capacitances. Further, the impact of temperature variations (250 K to 450 K) studied for different sheet variations (1 to 5) and noticed that analog/RF such as gm, gds, fT, TFP and GTFP are enhanced by 40.82%, 28.76%, 40.69%, 64.62% and 70.59%, respectively at lower temperature (250 K) when compared to high temperature (450 K). These enhancements make the device is ideal for applications in cryogenic computing systems, satellites, deep space probes, and other aerospace technologies. Furthermore, as the circuit level implementation CMOS inverter and 5-stage ring oscillator (RO) are examined for different sheets and observed as sheets increase delay and EDP increases. For a CMOS inverter the NMH (0.295 V) and NML (0.280 V) are better at 2 sheets with a highest gain of 9.38 V/V. Hence, it is advised to use two or three sheets-based JL-NSFETs for high-performance and lower-power analog/RF applications.

An experimental study to evaluate the performance of variable-width channel cold plates for cooling rectangular Li-ion batteries

The limited cooling capacity of cold plates employing conventional channel designs represents a key obstacle in thermal management systems. The persistent growth of the thermal boundary layer and the uneven distribution of flow across the channels are the principal challenges encountered in this context. To overcome these challenges, this study aims to analyse a modified cold plate of obstructed variable-width channels that can improve the hydrothermal performance and temperature uniformity. Different shapes of pin fins and grooves with variable sizes that match the width of the variable-width channels are proposed. Specifically, four types of pin fins–grooves were used: ellipse, drop, rhombus and trapezoid. The traditional cold plate served as a basis for evaluating the performance of new designs of cold plates. In addition to the traditional cold plate, the four proposed designs of cold plates were manufactured from copper. Experiments were conducted with water as a working fluid under a laminar flow for a flow rate range of 0.004–0.04 kg s-1 and a discharge C-rate range of 1C–2C. Results indicated that the use of variable-width channels with all shapes of fins–grooves effectively contributed to improving the heat dissipation of the cold plate, accompanied with an increase in hydraulic pumping power. At the highest flow rate, the best improvement percentage in the Nusselt number of 82.5 % was achieved when trapezoidal pin fins–grooves were used; by contrast, the lowest pumping power increasing percentage of 33.2 % was obtained when elliptical pin fins–grooves were adopted. The best hydraulic/thermal performance was achieved when trapezoidal pin fins were utilised, with the highest figure of merit of 1.685.

Democratizing Access to Microfluidics: Rapid Prototyping of Open Microchannels with Low-Cost LCD 3D Printers.

Microfluidics offer user-friendly liquid handling for a range of biochemical applications. 3D printing microfluidics is rapid and cost-effective compared to conventional cleanroom fabrication. Typically, microfluidics are 3D printed using digital light projection (DLP) stereolithography (SLA), but many models in use are expensive (≥$10,000 USD), limiting widespread use. Recent liquid crystal display (LCD) technology advancements have provided inexpensive (<$500 USD) SLA 3D printers with sufficient pixel resolution for microfluidic applications. However, there are only a few demonstrations of microfluidic fabrication, limited validation of print fidelity, and no direct comparisons between LCD and DLP printers. We compared a 40 μm pixel DLP printer (∼$18,000 USD) with a 34.4 μm pixel LCD printer (<$380 USD). Consistent with prior work, we observed linear trends between designed and measured channel widths ≥4 pixels on both printers, so we calculated accuracy above this size threshold. Using a standard IPA-wash resin and optimized parameters for each printer, the average error between designed and measured widths was 2.11 ± 1.26% with the DLP printer and 15.4 ± 2.57% with the 34.4 μm LCD printer. Printing with optimized conditions for a low-cost water-wash resin designed for LCD-SLA printers resulted in an average error of 2.53 ± 0.94% with the 34.4 μm LCD printer and 5.35 ± 4.49% with a 22 μm LCD printer. We characterized additional parameters including surface roughness, channel perpendicularity, and light intensity uniformity, and as an application of LCD-printed devices, we demonstrated consistent flow rates in capillaric circuits for self-regulated and self-powered delivery of multiple liquids. LCD printers are an inexpensive alternative for fabricating microfluidics, with minimal differences in fidelity and accuracy compared with a 40X more expensive DLP printer.

Direct calculation of the eddy viscosity operator in turbulent channel flow at Re τ = 180

This study aims to quantify how turbulence in a channel flow mixes momentum in the mean sense. We applied the macroscopic forcing method (Mani &amp; Park, Phys. Rev. Fluids, 2021, 054607) to direct numerical simulation (DNS) of a turbulent channel flow at $Re_\tau =180$ using two different forcing strategies that are designed to separately assess the anisotropy and non-locality of momentum mixing. In the first strategy, the leading term of the Kramers–Moyal expansion of the eddy viscosity is quantified, revealing all 81 tensorial coefficients that essentially characterise the local-limit eddy viscosity. The results indicate the following: (1) the eddy viscosity has significant anisotropy, (2) Reynolds stresses are generated by both the mean strain rate and mean rotation rate tensors associated with the momentum field and (3) the local-limit eddy viscosity generates asymmetric Reynolds stress tensors. In the second strategy, the eddy viscosity is quantified as an integration kernel revealing the non-local influence of the mean momentum gradient at each wall-normal coordinate on all nine components of the Reynolds stresses over the channel width. Our results indicate that while the shear component of the Reynolds stress is reasonably reproduced by the local mean gradients, other components of the Reynolds stress are highly non-local. These results provide an understanding of anisotropy and non-locality requirements for closure modelling of momentum transport in attached wall-bounded turbulent flows.

An Investigation of Convective Boundary Layer Depth and Entrainment Zone Properties Using Dual-Polarization Radar and Balloon-Borne Observations

Abstract Previous work has shown that differential reflectivity (ZDR) observations from National Weather Service dual-polarization Doppler weather radars (WSR-88Ds) provide accurate estimates of convective boundary layer (CBL) depth when compared with depth estimates from 0000 UTC rawinsonde observations. We extend this work by launching small rawinsondes, called Windsonds, to study ZDR signals throughout the daytime hours. Results show that it can be difficult to identify CBL depth from ZDR alone when biological scatterers are absent. The exploration of other radar variables leads to the use of azimuthal ZDR variance to help in identifying CBL characteristics. A variable that combines both ZDR and azimuthal ZDR variance, called DVar, allows for improved signal identification using the quasi-vertical profile (QVP) method. Furthermore, QVP channel width is found to be closely tied to overall entrainment zone (EZ) structure. Results show that the centers and vertical extents of channels of reduced DVar in QVPs correlate well with sounding-observed CBL depth and EZ depth, respectively, across all stages of CBL development and in both clear and cloud-topped CBLs. The QVP approach tends to fail in identifying CBL and EZ depths when the vertical gradient in moisture above the CBL is small. Additionally, we compare observed EZ depth to various EZ parameterizations and show that the parameterizations generally underestimate EZ depth. We conclude that the ability of WSR-88Ds to sample the CBL should be leveraged to increase our knowledge of CBL properties.

A New Algorithm Model Based on Extended Kalman Filter for Predicting Inter-Well Connectivity

Given that more and more oil reservoirs are reaching the high water cut stage during water flooding, the construction of an advanced algorithmic model for identifying inter-well connectivity is crucial to improve oil recovery and extend the oilfield service life cycle. This study proposes a state variable-based dynamic capacitance (SV-DC) model that integrates artificial intelligence techniques with dynamic data and geological features to more accurately identify inter-well connectivity and its evolution. A comprehensive sensitivity analysis was performed on single-well pairs and multi-well groups regarding the permeability amplitude, the width of the high permeable channel, change, and lasting period of injection pressure. In addition, the production performance of multi-well groups, especially the development of ineffective circulation channels and their effects on reservoir development, are studied in-depth. The results show that higher permeability, wider permeable channels, and longer injection pressure maintenance can significantly enhance inter-well connectivity coefficients and reduce time-lag coefficients. Inter-well connectivity in multi-well systems is significantly affected by well-group configuration and inter-well interference effects. Based on the simulation results, the evaluation index of ineffective circulation channels is proposed and applied to dozens of well groups. These identified ineffective circulation channel changing patterns provide an important basis for optimizing oil fields’ injection and production strategies through data-driven insights and contribute to improving oil recovery. The integration of artificial intelligence enhances the ability to analyze complex datasets, allowing for more precise adjustments in field operations. This paper’s research ideas and findings can be confidently extended to other engineering scenarios, such as geothermal development and carbon dioxide storage, where AI-based models can further refine and optimize resource management and operational strategies.

Phylogenomic and anatomical evidence for the Late Cretaceous diversification of African characiform fishes, including a new family, under the influence of the Trans-Saharan Seaway

Abstract Geological evidence supports the occurrence of an epicontinental Trans-Saharan Seaway bisecting the African continent during the Late Cretaceous to early Paleogene. The seaway formed a wide saltwater channel connecting the Neotethys with the South Atlantic, yet no previous study has investigated its impact on freshwater fish diversification. Phylogenomic data and time-calibrated trees indicate a Late Cretaceous signature for the appearance of three modern lineages of characiform fishes. Phylogenetic analyses using ultraconserved elements of 83 characiforms reveals that Alestidae, Hepsetus, and Lepidarchidae fam. nov. originated during the Santonian-Campanian of the Late Cretaceous (84–77.5 million years ago; Ma). Lepidarchidae consists of two monotypic taxa not previously recognized as sister species: the Niger tetra Arnoldichthys endemic to the lower Niger and Ogun rivers of Nigeria, and the dwarf jellybean tetra Lepidarchus from coastal rivers of Ghana, Côte d'Ivoire, Liberia, Sierra Leone, and Guinea. Microcomputed tomography scans (µCT) of 117 characiforms provide three novel morphological characters supporting Hepsetus and Lepidarchidae, four characters for monophyly of Lepidarchidae and five for a restricted Alestidae. The Santonian-Campanian divergence indicates allopatric speciation processes influenced by the Trans-Saharan Seaway, partitioning the African ichthyofauna in a west-east orientation. The timing for African characiform cladogenesis aligns with the Cenomanian fossil record and is circa 16–23 Ma younger than the earliest characiform-like fossils from Late Cretaceous outcrops of Morocco and Sudan. This study highlights the magnitude of Cretaceous transgression events shaping the freshwater biota and gaps in our understanding of the evolutionary history and paleobiogeography of ray-finned fishes across the African continent.

Redesign for channel width to improve temperature distribution: Investigation of minimum guaranteed channel width effects

Due to the high-temperature environment of solid oxide fuel cells (SOFCs), heat dissipation and uniform heat distribution within the cell are crucial for stable operation and prevention of degradation. In this study, instead of introducing obstacles increasing the average cell temperature, method for optimizing channel width is proposed to improve flow uniformity (Γ) and temperature distribution. The width calculation for redesign in this study is derived from the Hagen–Poiseuille equation and the Reynolds number formula. To prevent excessive variations in channel width and account for the unpredictable flow environment within the interconnect, a minimum guaranteed channel width (wmg) is incorporated. The optimization is evaluated using computational fluid dynamics simulations for the 1-inlet-1-outlet and 2-inlet-1-outlet configurations. The analysis considers varying mass flow rates (0.5m·, m·, 2m·, 4m·) and different current densities (6000, 8000, and 10000 A/m2) to assess these conditions' effects on wmg. Consequently, the Γ improves to 88–95 % across all operating conditions, leading to a more uniform temperature distribution near the edges and a reduction in the mean temperature of the positive electrode-electrolyte-negative electrode layer compared to the original model. Additionally, the optimal model is defined as 1-inlet-1-outlet configuration with wmg of 0.25 mm, ensuring uniformity over 80 % under all conditions. For optimal model, the power density considering blower input work is compared, resulting in up to approximately 7 % improvement in the net power density at concentration loss region. These results demonstrate that channel width redesign with wmg offers a novel solution for enhancing power density and temperature distribution in SOFCs.

Skyrmion flow in periodically modulated channels.

Magnetic skyrmions, topologically stabilized chiral magnetic textures with particlelike properties, have so far primarily been studied statically. Here, we experimentally investigate the dynamics of skyrmion ensembles in metallic thin film conduits where they behave as quasiparticle fluids. By exploiting our access to the full trajectories of all fluid particles by means of time-resolved magneto-optical Kerr microscopy, we demonstrate that boundary conditions of skyrmion fluids can be tuned by modulation of the channel geometry. We observe as a function of channel width deviations from classical flow profiles even into the no- or partial-slip regime. Unlike conventional colloids, the skyrmion Hall effect can also introduce transversal flow asymmetries and even local motion of single skyrmions against the driving force which we explore with particle-based simulations, demonstrating the unique properties of skyrmion liquid flow that uniquely deviates from previously known behavior of other quasiparticles.