Hasil untuk "Harbors and coast protective works. Coastal engineering. Lighthouses"

Shanghong Zhang, Hao Jia, Caihong Tang et al.

Aquatic vegetation plays a crucial role in regulating sediment transport and maintaining the stability of aquatic ecosystems. To investigate the turbulence structure and suspended sediment distribution under the influence of natural flexible submerged vegetation, this study selected Vallisneria natans (eelgrass), a representative flexible submerged plant, as the experimental material. Systematic measurements of flow structure and suspended sediment concentration (SSC) were conducted under submerged vegetation conditions. The experimental results demonstrated that the presence of flexible vegetation significantly altered the vertical distribution of flow velocity and turbulence characteristics. Under different vegetation densities, noticeable variations were observed in time-averaged velocity, lateral and vertical Reynolds stresses, and turbulent kinetic energy (TKE), with particularly pronounced changes in the near-bed and canopy regions. Compared to the bare bed condition, SSC in vegetated flows was significantly reduced, and the reduction became more evident with increasing vegetation density. To predict the SSC profiles under flexible vegetation conditions, the vertical distribution of the turbulent diffusion coefficient was calculated. Results showed that the coefficient exhibited a linear distribution within the canopy, reaching a maximum near the canopy top. Based on this distribution pattern, an improved Rouse equation applicable to submerged flexible vegetation conditions was proposed. The modified Rouse model was validated against measured SSC profiles under various vegetation densities and hydraulic conditions, demonstrating its ability to accurately predict the vertical distribution of suspended sediment. This study provides theoretical support for sediment transport modeling, hydrodynamic regulation, and ecological restoration in vegetated riverine and lacustrine environments. It also lays a foundation for advancing the understanding of the coupled interactions among flow, sediment, and vegetation.

Jun Zhang, Yingbiao Shi, Guojian He

The critical condition of sediment incipient motion (SIM) is one of the most pivotal and fundamental topics for the mechanics of sediment transport in offshore areas. The flocculation of fine sediment exerts a complex influence on SIM, particularly in bay areas where the water salinity varies. This paper analyzes data measured in Hangzhou Bay with 50 observation points from 2005 to 2019. The objective is to ascertain the effect of salinity on the critical velocity of SIM (uc), figure out the calculation error of traditional equations for uc in saline water and improve the calculation accuracy of uc. Results indicate that the calculation error rate of traditional uc equations escalates with the increased clay content of bottom sediment and water salinity. An improved uc equation in saline water environment is constructed with the consideration of clay content and salinity based on a traditional equation. The improved equation is fitted through measured data and validated with the experimental data. The accuracy of the improved equation significantly increases compared to traditional equations in the area with clay content over 15% and salinity over 12‰.

I. Möller, K. O’Leary

Athanasios T. Vafeidis, Leigh MacPherson, Sunna Kupfer et al.

The record storm surge of October 2023, which hit the southwestern German Baltic Sea, not only resulted in significant damages to coastal communities and infrastructure but also demonstrated that the region was prepared and able to avoid loss of lives and other catastrophic impacts. Numerical modelling has been a key tool utilised for providing information to support coastal flood management, at different levels of planning, for such events. Based on recent research conducted in the Baltic coast region as well as on empirical evidence acquired during the event, we present an operational scheme that utilises modelling tools and frameworks for supporting coastal flood management in the region. In this context, we distinguish between three successive phases of an extreme surge event and propose specific actions for each of these phases, aiming towards the development of an operational framework for managing events of high magnitude for the German Baltic Sea region and beyond.

Emanuelle Bezerra Maciel, Maria Luísa de Araújo Albuquerque, André Luiz Machado Pessanha

Intraspecific variations in the morphological traits of juveniles and adults of the Brazilian silverside, <i>Atherinella brasiliensis,</i> from three estuarine habitats were studied to understanding whether their morphology interacts with their dietary composition and habitat structure. For each individual, fourteen morphological measurements and eight functional traits were recorded related to food acquisition and locomotion. The highest abundance of <i>A. brasiliensis</i> was recorded in mudflats, which were often associated with a greater number of juveniles. Overall, 392 <i>A. brasiliensis</i> stomachs were examined, and their diet comprised mainly zooplankton organisms, followed by insects and benthic crustaceans. Among the morphological measures, our data revealed that in vegetated habitats (seagrass and riparian vegetation), individuals showed a higher oral gape surface and caudal peduncle and fed predominately on epibiotic or benthic fauna, while for individuals that had bigger eyes in unvegetated habitats (mudflat), this facilitated the ingestion of zooplankton and diatoms. Furthermore, a greater relative body height recorded in unvegetated habitats enhanced swimming performance and was linked to the effects of the lowest habitat structure. The results highlight the significant effects of morphological variation on juvenile and adult food acquisition and swimming ability.

Meng Chen, Xinping Zhang, Xiong Xiao et al.

The isotope tracing method provides a novel way to investigate the underlying mechanisms of water balance. This study focused on Taozi Lake in Changsha, a city in the subtropical monsoon region. We conducted continuous monitoring of meteorological factors and stable isotopes in precipitation and lake water samples and further employed the isotope mass balance model to estimate the evaporation to inflow ratio (E/I). The results revealed that the fitted slope of the lake water evaporation line (SLEL) was close to or even greater than the slope of the local meteoric water line (SLMWL) because of the inverse seasonal variations in precipitation isotopes and evaporation intensity. This led to significant depletion of stable isotopes in the water source. Conversely, the theoretical SLEL values derived from the Craig‒Gordon model provided a more accurate depiction of the evaporation enrichment processes of lake water and were more appropriate for identifying lake water sources. The E/I ratios exhibited seasonal variations, with the highest values occurring in autumn and the lowest values occurring in spring, reflecting the interplay between precipitation and evaporation. The interannual variability in the E/I ratios and lake water isotopes further underscored the lake's response to changing hydrometeorological conditions. The uncertainty in the E/I simulations was due primarily to the isotopic compositions of the inflow water and atmospheric vapor, followed by the relative humidity and surface water temperature. This study enhances our understanding of regional hydrological processes, particularly regarding lake water isotopes and simulations of lake water balance, while considering the uncertainties associated with the assumptions and input variables of the E/I ratio.

Leo van Rijn, Marcio Boechat Albernaz, Luitze Perk et al.

This study is focused on the experimental and numerical modelling of sand and mud transport over mud-sand beds with percentages of fines (< 63 μm) up to 50% in conditions with currents, waves and combined currents and waves. Both field and laboratory experiments with mud-sand beds have been performed. Detailed measurements of near-bed hydrodynamic and sediment transport processes have been made in the muddy tidal ferry channel between Holwerd and Ameland in the Dutch part of Wadden Sea. Laboratory flume experiments with currents and waves over a pure fine sand bed show the generation of small-scale sand ripples and strong ripple-induced vortex motions resulting in relatively high sand concentrations close to the bed. The near-bed sediment dynamics of a fine sand bed change drastically when a small amount of cohesive sediments (mud 10%–15%) is added to the sand bed. Bed properties which are changed are the percentage of fines, the dry bulk density (packing) and the cohesivity. The results of exploratory long-bed experiments with various mud-sand mixtures show that the mud particles at the mud-sand surface are washed out and small-scale isolated barchan-type sand ripples develop at the bed surface. The bed ripple heights are suppressed resulting in flatter ripples with less vorticity and as a consequence lower sand concentrations and transport. The critical bed-shear stress (cbs) is not much influenced by cohesive effects if the percentage of fines (< 63 μm) is smaller than about 15%, while for pfines > 15%, the critical bed-shear stress increases for increasing values of pfines. Laboratory results also indicate that the bed ripple development and near-bed sand transport may already be affected for a lower percentage of fines (10%–15%). Various modelling methods are used and discussed, both for the flume and field data.

Giuliana Marletta, Andrea Lombardo, Donatella Serio et al.

This study explored the occurrence, density, and distribution of Fucales along the island of Lampedusa, almost 30 years after the latest studies conducted on the marine vegetation of this island. To carry out this study, we conducted a monitoring activity in 18 sites through both scuba dives and snorkeling. During this study, a total of 13 species (three belonging to <i>Cystoseira</i> sensu strictu (s.s.), five to <i>Ericaria</i>, two to <i>Gongolaria</i>, and finally three to <i>Sargassum</i>) were observed. Nine species were previously reported, four taxa <i>(E. brachycarpa</i>, <i>E. funkii</i>, <i>E. giacconei</i>, and <i>S.</i> cf <i>furcatum</i>) were reported here for the first time in Lampedusa, and six species have not been found anymore. <i>Ericaria giacconei</i> may have always been present on Lampedusa Island, but it might have been misidentified in the past. The record on the island of Lampedusa extends the known distribution range of this species. The presence of <i>S.</i> cf <i>furcatum</i>, a non-indigenous species that is recently expanding in the Mediterranean Sea, could be considered further proof of ongoing seawater warming. In conclusion, we found that the predominant species’ association described in the past for the island of Lampedusa has remained unchanged in terms of species and biodiversity found in the studied sites. Nevertheless, we observed some changes in the Fucalean species, in particular a reduction in the canopy density values of some deep species. Therefore, we believe that the zonation pattern of the MPA should be revised, paying more attention to the conservation of fucalean species. Moreover, it will be important to manage and control the populations of the rabbitfishes, mitigating their impacts on the fucalean stands of the island.

Dandan Li, Xiaoyan Chen, Pingzong Zhu et al.

As a specific near surface hydrological condition, soil saturation can significantly affect the critical hydrodynamic characteristic and soil erosion rate of rill formation, leading to severe rill erosion. Nevertheless, few studies have investigated the characteristics of critical hydrodynamic parameters and their relationships with rill erosion rate under critical hydrodynamic conditions of rill formation on saturated soil slopes. Consequently, the quantification of critical hydrodynamic parameters and their effects on rill erosion rate under critical hydrodynamic conditions of rill formation on saturated soil slopes is of great significance for understanding the dynamic mechanism of rill formation and evolution and for predicting and controlling soil loss. In this study, indoor simulated rainfall experiments were performed and a new analytical model (Vc(NAM)) was applied to calculate the aforementioned critical parameters under a wide range of hydraulic conditions comprising five slope gradients (SG) (2°, 5°, 10°, 15°, and 20°) and three rainfall intensities (RI) (30, 60, and 90 mm/h). The results indicated that the new analytical model (Vc(NAM)) was suitable for estimating critical hydrodynamic parameters on saturated soil slopes. The critical flow velocity (Vc), the critical shear stress (τc), and the critical stream power (ωc) apparently increased, whereas the critical rill length (Lc) decreased with the increase of slope gradients and rainfall intensities. Moreover, the erosion rate at the critical condition increased with decreasing Lc and increasing Vc, τc, and ωc. Pearson correlation analysis indicated that τc and ωc were significantly positively correlated, whereas Lc was negatively correlated with erosion rate under the critical conditions. Stepwise regression analysis revealed that the erosion rate under critical hydrodynamic conditions of rill formation could be well predicted by τc (R2 = 0.83) with the linear model. The results provide an accurate model for evaluating critical conditions of rill formation and a basis for further understanding the intrinsic dynamic mechanism of rill formation on saturated soil slopes.

Vandana Sukumaran, Bramha Dutt Vishwakarma

A novel dynamically varying search radius algorithm is developed that takes advantage of bathymetry information to choose satellite observations that represent coastal sea level variability better. The algorithm is successfully tested at 155 tide gauge stations around the globe and demonstrates broader applicability across different coastal regimes compared to existing validation methods. This is supported by consistently higher median correlation and lower median Normalized Root Mean Square Error (NRMSE). Furthermore, the new algorithm improves the efficacy of the low-resolution product, X-TRACK SLA L2P v2022 (XTRACK), and makes it comparable to the high-resolution (20Hz) coastal products: Along-track sea level anomalies and trends v2.3. Using the algorithm at over 267 stations, XTRACK data shows improved agreement with tide gauges for both linear and non-linear trends. In some regions, such as tidally-dominated estuaries and the Eastern Australian coast, lower correlation and higher RMSE for residual signals are reported, which are discussed.

Dipin Khati, Yijin Liu, David N. Palacio et al.

Applications of Large Language Models (LLMs) are rapidly growing in industry and academia for various software engineering (SE) tasks. As these models become more integral to critical processes, ensuring their reliability and trustworthiness becomes essential. Consequently, the concept of trust in these systems is becoming increasingly critical. Well-calibrated trust is important, as excessive trust can lead to security vulnerabilities, and risks, while insufficient trust can hinder innovation. However, the landscape of trust-related concepts in LLMs in SE is relatively unclear, with concepts such as trust, distrust, and trustworthiness lacking clear conceptualizations in the SE community. To bring clarity to the current research status and identify opportunities for future work, we conducted a comprehensive review of $88$ papers: a systematic literature review of $18$ papers focused on LLMs in SE, complemented by an analysis of 70 papers from broader trust literature. Additionally, we conducted a survey study with 25 domain experts to gain insights into practitioners' understanding of trust and identify gaps between existing literature and developers' perceptions. The result of our analysis serves as a roadmap that covers trust-related concepts in LLMs in SE and highlights areas for future exploration.

Timothy A. Brumfiel, Revanth Konda, Drew Elliott et al.

To address the issues that arise due to the manual navigation of guidewires in endovascular interventions, research in medical robotics has taken a strong interest in developing robotically steerable guidewires, which offer the possibility of enhanced maneuverability and navigation, as the tip of the guidewire can be actively steered. The COaxially Aligned STeerable (COAST) guidewire robot has the ability to generate a wide variety of motions including bending motion with different bending lengths, follow-the-leader motion, and feedforward motion. In our past studies, we have explored different designs of the COAST guidewire robot and developed modeling, control, and sensing strategies for the COAST guidewire robot. In this study, the performance of a modified COAST guidewire robot is evaluated by conducting navigation experiments in an anatomical phantom model with pulsatile flow. The modified COAST guidewire robot is a simplified version of the COAST guidewire robot and consists of two tubes as opposed to three tubes. Through this study, we demonstrate the effectiveness of the modified COAST guidewire robot in navigating the tortuous phantom vasculature.

Raúl R. Rodríguez-Berríos, Jeremy A. Rodríguez-Vargas, Francisco Colón-Cartagena et al.

The coastal region of the Caribbean is notable for the chemical diversity found in its sponge products, resulting in the biosynthesis of a range of natural marine products, including polyketides. The objective of this manuscript is to summarize the isolated polyketides from sponges of the genus <i>Plakortis</i> located around the Caribbean coasts. This review provides a comprehensive overview of specimen location, isolation procedures, characterization methods, and biological assay studies of about 95 polyketides isolated from 1978 to 2024 in the Caribbean coasts of The Bahamas, Cayman Islands, Belize, Dominica, Jamaica, Martinique, Panamá, Puerto Rico, and Tobago. The Caribbean polyketides have been isolated from different types of <i>Plakortis</i> sp., such as <i>P. simplex</i>, <i>P. halichondroides</i>, <i>P. zyggompha</i>, and <i>P. angulospiculatus</i>, which have demonstrated antimicrobial, anticancer, anti-inflammatory, antiparasitic, and antiviral activities. A variety of linear polyketides with different functionalities have been reported, including endoperoxides (1,2-dioxane), lactones, indane-type bicyclics (spiculane and zyggomphic), alcohols, alkenes, styryl groups, <i>α</i>,<i>β</i>-unsaturated carboxylic acids, and ketones, as well as related natural products of biosynthetic origin. The aim is to encourage further exploration by researchers in the Caribbean’s coastal marine environments, promoting the discovery and investigation of novel polyketide cyclic peroxides and related secondary metabolites to identify additional bioactive medicinal natural products.

Scott J. Morrissey, Dean R. Jerry, Michael J. Kingsford

Challenges associated with cubozoan jellyfish detection and the limitations of current detection techniques limit the ability of scientists to fill critical knowledge gaps surrounding their ecology. Environmental DNA (eDNA), however, has proven useful as an ecological survey tool to detect and study these deadly jellyfish. This study aimed to leverage the power of eDNA to detect and explore the distribution of the Australian box jellyfish (<i>Chironex fleckeri</i>), encompassing both its medusae and polyp life history stages, within an open coastal bay (Horseshoe Bay) of Magnetic Island, Queensland, Australia. Our investigation focused on a hypothesis concerning the source locations of the jellyfish within Horseshoe Bay and, through a comparison of both life history stage distributions, aimed to determine potential population stock boundaries. eDNA results aligned with the predicted nearshore distribution of medusae. Further, the elusive benthic polyp stage was also detected. These findings confirmed Horseshoe Bay as a source location of the jellyfish. Moreover, our evidence supported a model that the area likely represents a population stock of the species. This adds to growing evidence suggesting some cubozoan jellyfish have population stocks of small spatial scales in both open and relatively closed ecosystems such as estuaries. In conclusion, this study serves as a notable example of eDNA’s ability to resolve critical knowledge gaps surrounding cubozoan ecology and to enhance the management ability of these deadly jellyfish to reduce envenomations.

Brooke Harowitz, Catherine C. Macdonald, Julia Wester

“Red tide” is the popular name for a harmful algal bloom that occurs frequently in Florida waters and has significant impacts on the environment, the economy, and human and animal health. This paper addresses the limited understanding of public attitudes surrounding red tide and the potential for message framing to increase support for mitigation action. A sample of Florida residents (n = 498) was randomly shown a digital article framed around different red tide impacts (economic loss, human health risks, ecosystem damage, or harm to charismatic species) or a control article not framed around a specific red tide impact. Participants were then queried about their emotional responses, support for red tide mitigation policies, and intentions to change their behavior to mitigate impacts. Participants reported higher levels of negative emotions after viewing the harm to charismatic megafauna framing, indicating that messaging may play a significant role in eliciting environmental emotions. Message frames did not significantly impact other policy attitudes. Results demonstrate barriers to shifting support for mitigation where public support for action is already high.

Sayan Chatterjee, Ching Louis Liu, Gareth Rowland et al.

The increasing popularity of AI, particularly Large Language Models (LLMs), has significantly impacted various domains, including Software Engineering. This study explores the integration of AI tools in software engineering practices within a large organization. We focus on ANZ Bank, which employs over 5000 engineers covering all aspects of the software development life cycle. This paper details an experiment conducted using GitHub Copilot, a notable AI tool, within a controlled environment to evaluate its effectiveness in real-world engineering tasks. Additionally, this paper shares initial findings on the productivity improvements observed after GitHub Copilot was adopted on a large scale, with about 1000 engineers using it. ANZ Bank's six-week experiment with GitHub Copilot included two weeks of preparation and four weeks of active testing. The study evaluated participant sentiment and the tool's impact on productivity, code quality, and security. Initially, participants used GitHub Copilot for proposed use-cases, with their feedback gathered through regular surveys. In the second phase, they were divided into Control and Copilot groups, each tackling the same Python challenges, and their experiences were again surveyed. Results showed a notable boost in productivity and code quality with GitHub Copilot, though its impact on code security remained inconclusive. Participant responses were overall positive, confirming GitHub Copilot's effectiveness in large-scale software engineering environments. Early data from 1000 engineers also indicated a significant increase in productivity and job satisfaction.

Sergio Rico

Case studies are a popular and noteworthy type of research study in software engineering, offering significant potential to impact industry practices by investigating phenomena in their natural contexts. This potential to reach a broad audience beyond the academic community is often undermined by deficiencies in reporting, particularly in the context description, study classification, generalizability, and the handling of validity threats. This paper presents a reflective analysis aiming to share insights that can enhance the quality and impact of case study reporting. We emphasize the need to follow established guidelines, accurate classification, and detailed context descriptions in case studies. Additionally, particular focus is placed on articulating generalizable findings and thoroughly discussing generalizability threats. We aim to encourage researchers to adopt more rigorous and communicative strategies, ensuring that case studies are methodologically sound, resonate with, and apply to software engineering practitioners and the broader academic community. The reflections and recommendations offered in this paper aim to ensure that insights from case studies are transparent, understandable, and tailored to meet the needs of both academic researchers and industry practitioners. In doing so, we seek to enhance the real-world applicability of academic research, bridging the gap between theoretical research and practical implementation in industry.

Emeralda Sesari, Federica Sarro, Ayushi Rastogi

Software practitioners discuss problems at work with peers, in-person and online. These discussions can be technical (e.g., how to fix a bug?) and social (e.g., how to assign work fairly?). While there is a growing body of knowledge exploring fairness problems and solutions in the human and social factors of software engineering, most focus has been on specific problems. This study provides fairness discussions by software practitioners on Stack Exchange sites. We present an exploratory study presenting the fairness experience of software practitioners and fairness expectations in software teams. We also want to identify the fairness aspects software practitioners talk about the most. For example, do they care more about fairness in income or how they are treated in the workplace? Our investigation of fairness discussions on eight Stack Exchange sites resulted in a list of 136 posts (28 questions and 108 answers) manually curated from 4,178 candidate posts. The study reveals that the majority of fairness discussions (24 posts) revolve around the topic of income suggesting that many software practitioners are highly interested in matters related to their pay and how it is fairly distributed. Further, we noted that while not discussed as often, discussions on fairness in recruitment tend to receive the highest number of views and scores. Interestingly, the study shows that unfairness experiences extend beyond the protected attributes. In this study, only 25 out of 136 posts mention protected attributes, with gender mainly being discussed.

Tom Robert Davis, David Harasti

Small no-take marine protected areas (MPAs) in urban settings can fail to adequately protect biodiversity due to the combined effects of illegal fishing and species emigrating outside the protected area boundaries. Further assessment of the effectiveness of these areas is needed to provide insights into how they can best be managed to generate conservation benefits. The Fly Point no-take MPA in Port Stephens, New South Wales, Australia, was used as a case study, with the objective of examining whether a small urban no-take MPA can produce conservation benefits, despite the handicaps imposed by its size and location. Diver-based underwater visual census data, recording fish species and abundances, was obtained from 434 surveys conducted in Port Stephens (2009–2022) at three sites within the Fly Point no-take MPA and at three surrounding sites open to fishing. These data were analysed using permutational multivariate analysis of variance to determine whether no-take protection significantly benefited fish species richness and diversity. We found significantly higher species richness for sites in the no-take MPA than in surrounding areas and significant differences in assemblages between no-take and fished areas, driven in part by greater abundances of two fishery-targeted species in the no-take MPA (<i>Acanthopagrus australis</i> and <i>Scorpis lineolata</i>). Generally, fish diversity was also significantly higher for sites within the no-take MPA, although diversity was also high in fished sites adjacent to the no-take MPA. Study results demonstrate that small urban no-take MPAs can provide conservation benefits, especially when these areas have been protected for more than a decade and where high visibility and local stewardship enable adequate enforcement of no-take restrictions. Consequently, planning for MPAs in urban areas should endeavour to ensure high levels of public support and, ideally, should situate MPAs in highly visible locations, in order to maximise their conservation outcomes.

Sehrish Malik, Moeen Ali Naqvi, Leon Moonen

There is an increasing need to assess the correct behavior of self-adaptive and self-healing systems due to their adoption in critical and highly dynamic environments. However, there is a lack of systematic evaluation methods for self-adaptive and self-healing systems. We proposed CHESS, a novel approach to address this gap by evaluating self-adaptive and self-healing systems through fault injection based on chaos engineering (CE) [ arXiv:2208.13227 ]. The artifact presented in this paper provides an extensive overview of the use of CHESS through two microservice-based case studies: a smart office case study and an existing demo application called Yelb. It comes with a managing system service, a self-monitoring service, as well as five fault injection scenarios covering infrastructure faults and functional faults. Each of these components can be easily extended or replaced to adopt the CHESS approach to a new case study, help explore its promises and limitations, and identify directions for future research. Keywords: self-healing, resilience, chaos engineering, evaluation, artifact