Stream Structure Research Articles

The impact of changes in water–sediment relationships at river confluences on the evolution of river bars

The confluence of tributaries and the main stream affects riverbed siltation and alters the upstream water–sediment relationships and flow structure of the main stream by adding additional flow. The relationship between these changes and the evolution of river bars, however, is yet to be fully understood. In this study, the areas of the river bars were extracted from Landsat image and analyzed using soft clustering to identify evolutionary patterns of the bars at the confluence of the Fen River (FR) and Yellow River (YR), and to analyze the hydrodynamic mechanism with hydrodynamic modeling. The results show that the spatial and temporal evolution of river bars in the study area over the past 50 years exhibits an evolutionary pattern, which exhibited evident clustering distributions and significant stage-based characteristics. This pertains to the water–sediment relationships as well as hydrodynamic fluctuations. At the confluence of FR and YR, the intensity of fluvial erosion experiences a mean increment of 9.67 %, while the incoming sediment coefficient witnesses a mean reduction of 5.74 %. The position of the confluence point exhibits a close association with the evolutionary characterized of spatial clustering and temporal phasing of the river bars. The river confluence area showcases a complex turbulence structure, wherein alterations in sediment transport capacity occur due to the influence of secondary flow and the topography of the confluence area. Consequently, this impacts the flushing of river sandbars and brings about modifications in siltation. Overall, this study provides the scientific basis for YR sediment management and channel modification in response to changing runoff and sediment conditions.

The Gulf Stream Structure and Meandering Based on the CTD and SADCP Measurements in 1989–1990 and 2014–2015

An review of field studies in the Gulf Stream region carried out by the authors in two periods with a break of 25 years is presented to summarize the results. The studies in the early period included hydrographic surveys in the area of a southern meander of the Gulf Stream (1989) and in the area of dividing of a single jet of the current into separate branches: in the Gulf Stream delta (1990). The second, recent, stage includes on-route surveys with SADCP profiler in 2014–2015 while crossing the meandering Gulf Stream at mid-latitudes to study its detailed high-resolution velocity field structure.

Lifecycle Assessment of Strategies for Decarbonising Wind Blade Recycling toward Net Zero 2050

The wind energy sector faces a persistent challenge in developing sustainable solutions for decommissioned Wind Turbine Blades (WTB). This study utilises Lifecycle Assessment (LCA) to evaluate the gate-to-gate carbon footprint of high-profile disposal and recycling methods, aiming to determine optimal strategies for WTB waste treatment in the UK. While this article analyses the UK as a case study, the findings are applicable to, and intended to inform, recycling strategies for WTB waste globally. Long-term sustainability depends heavily on factors like evolving energy grids and changing WTB waste compositions and these must be considered for robust analysis and development strategy recommendations. In the short to medium term, mechanical recycling of mixed WTB waste is sufficient to minimise Global Warming Potential (GWP) due to the scarcity of carbon fibre in WTB waste streams. Beyond 2040, carbon fibre recycling becomes crucial to reduce GWP. The study emphasises the importance of matching WTB sub-structure material compositions with preferred waste treatment options for the lowest overall impact. Future development should focus on the extraction of carbon fibre reinforced polymer (CFRP) structures in WTB waste streams, commercialising large-scale CFRP structure recycling technologies, establishing supply chains, and validating market routes for secondary carbon fibre products. In parallel, scaling up low-impact options, like mechanical recycling, is vital to minimise WTB waste landfilling. Developing viable applications and cost-effective market routes for mechanical recyclates is necessary to displace virgin glass fibres, while optimising upstream recycling processes based on product requirements.

Checking equivalence of corecursive streams: An inductive procedure

In recent work, non-periodic streams have been defined corecursively, by representing them with finitary equational systems built on top of various operators, besides the standard constructor. When only the stream constructor is allowed in equations, only periodic streams can be represented, and the structures of periodic streams and infinite regular trees are isomorphic. Therefore, one can use the theory of regular trees to get a sound and complete procedure to decide whether two equational systems are equivalent, that is, define the same streams. However, such an isomorphism no longer exists if one allows other operators in equations; in particular, there exist systems of equations which have the same unique solution as streams, but not as regular trees. Hence, equality of regular trees becomes stronger then equality of streams, with a negative impact on termination of functions whose definition is based on the equivalence of the representation of streams as finitary equational systems. To overcome this problem, we provide a weaker definition of equivalence, and prove its soundness and relative completeness. This definition is coinductive, hence non-algorithmic. However, we show that it can be turned into an equivalent inductive procedure.

Salamander loss alters montane stream ecosystem functioning and structure through top‐down effects

AbstractAmphibians are among the most endangered taxa worldwide, but little is known about how their disappearance can alter the functioning and structure of freshwater ecosystems, where they live as larval stages. This is particularly true for urodeles, which often are key predators in these ecosystems. The fire salamander (Salamandra salamandra) is a common predator in European fresh waters, but the species is declining due to habitat loss and the infection by fungal pathogens. We studied the consequences of fire salamander loss from three montane streams, by comparing two key ecosystem processes (periphyton accrual and leaf litter decomposition) and the structure of three communities (periphytic algae, aquatic hyphomycetes and invertebrates) using stream enclosures with and without salamander larvae. Salamander loss did not cause changes in invertebrate abundance or community structure, except for one stream where abundance increased in the absence of salamander larvae. However, salamander loss led to lower periphyton accrual, changes in algal community structure and slower leaf litter decomposition, with no associated changes in fungal communities or microbial decomposition. The changes observed may have been caused by release of salamander predatory pressure on invertebrates, which could have promoted their grazing on periphyton, in contrast to their preference for leaf shredding in the presence of salamander. Our study demonstrates an important role of salamander larvae in montane streams through top‐down control of lower trophic levels and thus in regulating key stream ecosystem processes. Our results highlight the need for improving protection measures for amphibians to prevent these alterations on ecosystem structure and function.

Experimental and numerical investigations of the water surface profile and wave extrema of supercritical flows in a narrow channel bend

Supercritical flows in channel bends, e.g., in steep streams, chute spillways, and flood and sediment bypass tunnels (SBTs), experience cross-waves, which undulate the free surface. The designs of these hydraulic structures and flood protection retaining structures in streams necessitate computing the locations and water depths of the wave extrema. This study numerically and experimentally investigates the water surface profiles along the sidewalls, the wave extrema flow depths, and their angular locations in a narrow channel bend model of the Solis SBT in Switzerland. The 0.2 m wide and 16.75 m long channel has a bend of 6.59 m radius and 46.5° angle of deviation. The tested flow conditions produced Froude numbers ≈ 2 and aspect ratios ranging from 1.14 to 1.83. Two-phase flow simulations were performed in OpenFOAM using the RNG k–ε turbulence closure model and the volume-of-fluid method. The simulated angular locations of the first wave extrema and the corresponding flow depths deviate marginally, within ± 6.3% and ± 2.1%, respectively, from the experimental observations, which signifies good predictions using the numerical model. Larger deviations, especially for the angular locations of the wave extrema, are observed for the existing analytical and empirical approaches. Therefore, the presented numerical approach is a suitable tool in designing the height of the hydraulic structures with bends and conveying supercritical flows. In the future, the model’s application shall be extended to the design of the height and location of retaining walls, embankments, and levees in steep natural streams with bends.

Numerical investigation of acoustic streaming vortices in cylindrical tube arrays

Abstract Acoustic streaming has a significant effect on accelerating material mixing and flow field disturbance. To explore the characteristics of acoustic streaming in the cylindrical tube array field under the action of an acoustic wave, we derive the dimensionless acoustic streaming control equation and establish a numerical calculation model of acoustic streaming. The effects of acoustic incidence angle, acoustic Reynolds number, and Strouhal number on the acoustic streaming vortex flow field in the tube array were investigated. The numerical results show that with the change in acoustic parameters, the acoustic streaming in the tube array presents rich changes in the vortex flow field, and there are flow field phenomena such as shrinking, merging, tearing, and splitting of the vortex structure. Toward the walls of each tube, there is a strong acoustic streaming flow velocity. Besides, there is also a large streaming velocity on the interface of the adjacent acoustic streaming vortices. The inner streaming vortex structure in the acoustic boundary layer decreases with the increase in the acoustic Reynolds number, but the intensity of the inner streaming vortex and outer streaming vortex increases rapidly, and the disturbance effect of the flow field is enhanced. With the increase in the dimensionless acoustic frequency (or Strouhal number), although the structure and intensity of the inner streaming vortex decrease, the velocity gradient on the wall of the cylindrical tube increases, which is beneficial to destroy the flow boundary layer of the cylindrical tube wall and accelerate the instability of the wall flow field.

Method of aggregating temporal multimodal streaming data from iot devices based on reactive programming

Recent advancements in Internet of Things (IoT) technologies have led to an exponential increase in the generation of temporal multimodal streaming data from various IoT devices. Aggregating and processing this data efficiently poses significant challenges, including scalability, reliability, and synchronization issues. This paper proposes a novel method for aggregating temporal multimodal streaming data from IoT devices based on reactive programming principles. We begin by analyzing recent research and publications in the field to identify existing challenges and limitations in aggregating temporal data from IoT devices. The key problem addressed in this study is the efficient aggregation of data streams while ensuring scalability, reliability, and synchronization across different devices. The primary objective of this research is to develop a method that can hierarchically organize and aggregate temporal data streams from IoT devices while addressing the challenges of scalability and reliability. To achieve this, we leverage reactive programming techniques, specifically the GroupJoin operation, which allows for the seamless integration of data streams from multiple sources. Our method involves initializing the aggregation process by passing relevant data streams from two devices to the GroupJoin operation and configuring the settings for operation. Additionally, we introduce flexibility in the aggregation process by allowing for the hierarchical structuring of data streams based on physical or logical criteria. Furthermore, we discuss the implementation of our proposed method using the Rx library for .NET, which provides implementations for various programming languages, ensuring its adaptability across different platforms. We benchmark the performance of our method against a naive implementation, demonstrating its efficiency and scalability in aggregating temporal data streams from IoT devices. In conclusion, our proposed method offers a scalable and reliable solution for aggregating temporal multimodal streaming data from IoT devices. By leveraging reactive programming principles, we address key challenges in data aggregation and provide a flexible method for organizing and processing data streams efficiently.

Evaluation of ChatGPT and Gemini large language models for pharmacometrics with NONMEM.

To assess ChatGPT 4.0 (ChatGPT) and Gemini Ultra 1.0 (Gemini) large language models on NONMEM coding tasks relevant to pharmacometrics and clinical pharmacology. ChatGPT and Gemini were assessed on tasks mimicking real-world applications of NONMEM. The tasks ranged from providing a curriculum for learning NONMEM, an overview of NONMEM code structure to generating code. Prompts in lay language to elicit NONMEM code for a linear pharmacokinetic (PK) model with oral administration and a more complex model with two parallel first-order absorption mechanisms were investigated. Reproducibility and the impact of "temperature" hyperparameter settings were assessed. The code was reviewed by two NONMEM experts. ChatGPT and Gemini provided NONMEM curriculum structures combining foundational knowledge with advanced concepts (e.g., covariate modeling and Bayesian approaches) and practical skills including NONMEM code structure and syntax. ChatGPT provided an informative summary of the NONMEM control stream structure and outlined the key NONMEM Translator (NM-TRAN) records needed. ChatGPT and Gemini were able to generate code blocks for the NONMEM control stream from the lay language prompts for the two coding tasks. The control streams contained focal structural and syntax errors that required revision before they could be executed without errors and warnings. The code output from ChatGPT and Gemini was not reproducible, and varying the temperature hyperparameter did not reduce the errors and omissions substantively. Large language models may be useful in pharmacometrics for efficiently generating an initial coding template for modeling projects. However, the output can contain errors and omissions that require correction.

Two-stage channels can enhance local biodiversity in agricultural landscapes

Field drainage causes habitat loss, alters natural flow regimes, and impairs water quality. Still, drainage ditches often are last remnants of aquatic and wetland habitats in agricultural landscapes and as such, can be important for local biodiversity. Two-stage channels are considered as a greener choice for conventional ditches, as they are constructed to mimic the structure of natural lowland streams providing a channel for drainage water and mechanisms to decrease diffuse loading. Two-stage channels could also benefit local biodiversity and ecosystem functions, but existing information on their ecological benefits is scarce and incomplete. We collected environmental and biological data from six agricultural stream systems in Finland each with consequent sections of a conventional ditch and a two-stage channel to study the potential of two-stage channels to enhance aquatic and riparian biodiversity and ecological functions. Biological data included samples of stream invertebrates, diatoms and plants and riparian beetles and plants. Overall, both section types were highly dominated by few core taxa for most of the studied organism groups. Riparian plant and invertebrate communities seemed to benefit from the two-stage channel structure with adjacent floodplains and drier ditch banks. In addition, two-stage channel sections had higher aquatic plant diversity, algal productivity, and decomposition rate, but lower stream invertebrate and diatom diversity. Two-stage channel construction did not diversify the structure of stream channels which is likely one explanation for the lack of positive effects on benthic diversity. However, both section types harbored unique taxa found only in one of the two types in all studied organism groups resulting in higher local gamma diversity. Thus, two-stage channels enhanced local biodiversity in agricultural landscapes. Improvements especially in aquatic biodiversity might be achieved by increasing the heterogeneity of in-stream habitat structure and with further efforts to decrease nutrient and sediment loads.

Underwater image enhancement using Divide-and-Conquer network.

Underwater image enhancement has become the requirement for more people to have a better visual experience or to extract information. However, underwater images often suffer from the mixture of color distortion and blurred quality degradation due to the external environment (light attenuation, background noise and the type of water). To solve the above problem, we design a Divide-and-Conquer network (DC-net) for enhancing underwater image, which mainly consists of a texture network, a color network and a refinement network. Specifically, the multi-axis attention block is presented in the texture network, which combine different region/channel features into a single stream structure. And the color network employs an adaptive 3D look-up table method to obtain the color enhanced results. Meanwhile, the refinement network is presented to focus on image features of ground truth. Compared to state-of-the-art (SOTA) underwater image enhance methods, our proposed method can obtain the better visual quality of underwater images and better qualitative and quantitative performance. The code is publicly available at https://github.com/zhengshijian1993/DC-Net.

Identifying the environmental variables that predict crayfish assemblage structure in agricultural headwater streams

Identifying the environmental variables that predict crayfish assemblage structure in agricultural headwater streams

Strategy for Forming Neighborhood-Based Business Entities as A Motor for Community Economic Potential in Samarinda City, Indonesia

Government administration becomes a key success in developing the local potential sector. Mapping local potential, in this case, sub-districts is one of the important things to do to find and recognize economic potential that can be developed. Ideally, community economic activities at the sub-district level are carried out as institutions or business entities managed professionally but still rely on the area's potential. It can make community businesses more productive and effective. Thus, this study seeks to determine the potential for forming sub-district-based business entities as one of the economic drivers of the city of Samarinda. This study uses a qualitative approach to primary and secondary data. Also, the research location is 59 sub-districts in the city of Samarinda. A total of 59 village heads who were the target of this study, 55 people were willing to answer the questions. The data was analyzed using tabulating interviews through 9 blocks covering the Business Model Canvas components: Customer Segment, Value Proposition, Channel, Customer Relation, Revenue Stream, Key Resources, Key Activities, Key Partnerships, and Cost Structure. Also, Business Model Canvas and SWOT analysis. The result indicates that 10 sub-district-based business models have the most potential to be developed in Samarinda City, namely trading businesses (groceries, restaurants), home industry businesses (weaving, beads, amplang, fish floss, herbal medicine), service businesses (workshops, transportation services, Savings and Loans, motorbike washing, haircuts, sewing), Use of land that is not (RTH), Service-based environmental management system (such as environmental safety and environmental cleanliness), Become a wholesaler, for goods/needs that are for public consumption. Homestead agricultural food sector business (mushroom business, etc.), freshwater fish management, waste recycling, and tourism.

Swarming in stellar streams: Unveiling the structure of the Jhelum stream with ant colony-inspired computation

The halo of the Milky Way galaxy hosts multiple dynamically coherent substructures known as stellar streams that are remnants of tidally disrupted orbiting systems such as globular clusters (GCs) and dwarf galaxies (DGs). A particular case is that of the Jhelum stream, which is known for its unusual and complex morphology. Using the available data from the Gaia DR3 catalog, we extracted a region on the sky that contains Jhelum, and fine-tuned this selection by enforcing limits on the magnitude and proper motion of the selected stars. We then applied the novel Locally Aligned Ant Technique (LAAT) on the position and proper motion space of stars belonging to the selected region to highlight the stars that are closely aligned with a local manifold in the data and the stars belonging to regions of high local density. We find that the overdensity representing the stream in proper motion space is composed of two components, and show the correspondence of these two signals to the previously reported narrow and broad spatial components of Jhelum. We then made use of the radial velocity measurements provided by the S5 survey and confirm, for the first time, a separation between the stars belonging to the two components in radial velocity. We show that the narrow and broad components have velocity dispersions of 4.84+1.23-0.79 km s-1 and 19.49+2.19-1.84 km s−1, and metallicity dispersions of 0.15+0.18-0.10 and 0.34+0.13-0.09, respectively. These measurements, as well as the given difference in component widths, could be explained with a probable scenario where Jhelum is the remnant of a GC embedded within a DG and where both were accreted onto the Milky Way during their infall. Although the properties of Jhelum could be explained with this merger scenario, other progenitors of the narrow component remain possible such as a nuclear star cluster or a DG. To rule these possibilities out, we would need more observational data of member stars of the stream. Our analysis shows that the internal structure of streams holds great information on their past formation history, and therefore provides further insight into the merger history of the Milky Way.

The model of a discrete communication channel in the control channel of satellite communication systems

The control channels used in modern satellite communication systems (CCC) for multiplexers used in modern satellite communication systems are designed to transmit control messages regarding changes in the frame structures of organized compressed digital streams. Increased requirements are placed on the reliability of messages transmitted in these channels compared to messages transmitted in sealed channels. In the presence of phase flickering, as well as with a decrease in the signal-to-noise ratio (SNR) in communication channels formed on the basis of convolutional codes, the effect of grouping errors occurs at the input of decoders of noise-resistant codes in control channels. Therefore, information about the statistical properties of messages received at the input of a decoder designed to ensure the reliability of control channel messages is important in the synthesis of decoding algorithms capable of taking into account these statistical properties.

Effect of Hydrogel Matrix and Fluid Shear Stress on the Behavioral Regulation of Mesenchymal Stem Cells

Development of a micromodel that recapitulates multiple mechanical properties to mimic the complex mechanical microenvironment is crucial for cell‐based research. Herein, a microsystem combining structure of hydrogel matrix and acoustic streaming (AS) to mimic the cellular microenvironment is proposed, which can realize multiplex cellular mechanical cues, including matrix stiffness, fluid shear stress (FSS) generated by AS, and matrix roughness. The results demonstrate that the cell spreading area enlarges with the increase of matrix stiffness, and cell spreading is encouraged by integrin β1 cluster to polymerize actin when combines the hydrogel matrix with FSS. In addition, FSS has the influence on the roughness of the hydrogel, which further affects the cell morphology and mechanical properties, inducing mesenchymal stem cells (MSCs) differentiation into astrocytes rapidly. Meanwhile, cell migration is also enhanced by FSS stimulation, particularly, undifferentiated cells at 22 kPa hydrogel have the fastest migration speed, and change the movement model from contact inhibition to contact stimulation migration. Especially, matrix roughness and stiffness dominantly control of cell spreading and differentiation, whereas FSS affects cell migration. In conclusion, the microsystem in this work shows superior performance in regulating the spreading, differentiation, and migration of MSCs, which provides a new tool for cell‐microenvironment study.

Video process detection for space electrostatic suspension material experiment in China’s Space Station

The purpose of video process detection is to identify key processes of interest and associated semantic categories, which is an important computer vision task for localizing key processes in space science experiments. To detect experimental processes in space electrostatic suspension material experiment on China’s Space Station, we propose a Slow-and-Fast Dual-Stream Network. It extracts multi-scale temporal semantic information by designing a Slow-and-Fast Temporal Stream structure and effectively detects the experimental processes with various temporal scales. In addition, the Two Path Temporal Pyramid Network (TP2N) enhances the bi-direction flow among multi-scale features on the temporal dimension to alleviate boundary sensitivity. The validation experiments on our established dataset demonstrate the effectiveness of our proposed method with 62.43% mAP, outperforming the related state-of-the-art temporal action localization methods with nearly 7% mAP gain. This paper is the first application of deep learning in space electrostatic suspension material experiments on China’s Space Station and further provides important technical support for the identification of key processes in space science experiments.

Business development plan for Ngargogondo tourism village based on industry 4.0 technology

Ngargogondo Tourism Village is one of the tourist villages in Magelang Regency, which is in the Balai Ekonomi Desa (Balkondes) area of the Borobudur Region. This tourist village was newly formed and was inaugurated in 2021. Meanwhile, marketing success is one factor determining a tourist village's development. In addition, other more attractive and anti-mainstream developments are needed with the surrounding tourist villages. The current study applied a descriptive qualitative research by conducting observations and interviews. Then, the information and data were measured and analyzed utilizing marketing mix, SWOT, and Business Model Canvas (BMC) analyses. This research procedure also consisted of three stages: data collection, data analysis, and presentation of data analysis results. The focus on the data analysis is based on the 9 aspects, including customer segment, value proposition, channels, customer relationship, revenue stream, key resources, key activities, key partnership, and cost structure. Based on this, a study is required to identify the marketing potential of Ngargogondo Village based on the marketing mix and then analyzed based on SWOT and Business Model Canvas (BMC) to develop a tourism business development plan base on industry 4.0 technology. Further, the research results can be used to formulate a marketing strategy for the Ngargogondo Tourism Village to develop its tourism business.

Analysis of E-commerce Live Streaming and Traffic Generation

The Internet has become an integral part of our society. This paper focuses on TikTok, one of today's most popular Internet platforms, and analyzes its e-commerce live streaming structure and traffic generation methods. Through a comprehensive examination of TikTok's current status and prospects, this study aims to deepen our understanding of the current Internet model and identify emerging trends. TikTok's commercial liquidity is essential to its success as a commercial platform. However, balancing commercial interests with user experience has challenged the platform's development. The key to TikTok's growth is creating a sticky user base and fostering a unique platform culture. Rather than prioritizing commercial gain over user experience, TikTok aims to engage users in the commercial process, which is critical for sustainable development. Overall, this paper sheds light on the complexities of e-commerce live streaming and traffic generation on TikTok and highlights the platform's unique approach to balancing commercial interests with user experience.

Numerical simulation of acoustic streaming in standing waves

This study presents a numerical investigation of acoustic streaming motion (of the Rayleigh type) in a compressible gas inside two-dimensional rectangular enclosures. To numerically study the effects of the sound field intensity on the formation process of streaming structures, we propose to discretize the fully compressible form of the two-dimensional Navier-Stokes equations using a high-order (formally greater or equal to fourth-order) accurate numerical scheme in both space and time. The proposed numerical solver utilizes high-order compact schemes along each spatial dimension combined with a filtering procedure when it is necessary. Acoustic standing waves are excited inside the enclosures and the resulting acoustic streaming patterns are investigated for low and high-intensity waves, in both linear and nonlinear regimes following closely the work of Daru et al. (2013). An extended investigation indicates that without the incorporation of an appropriate filter, the application of the high-order compact schemes in case of fast streaming results in spurious oscillations which inhibit their applicability. Following the recent relevant literature, the numerical simulations performed demonstrate the ability of the proposed numerical approach to reproduce efficiently and robustly the transitions from regular acoustic streaming to irregular streaming and the relevant phenomena confirming results that have been previously presented.