Hasil untuk "Ocean engineering"

Xinlei Zhang, Mengyao Fang, Zhiyuan Bai et al.

As a novel perfluorooctane sulfonate (PFOS) alternative, 6:2 fluorotelomer sulfonamide alkylbetaine (6: 2 FTAB) has been detected in the environment and biotas. However, its behaviors and toxicity in earthworms remain unclear. Here, earthworms (<i>Eisenia fetida</i>) were exposed to 6:2 FTAB to investigate its bioaccumulation, biotransformation and toxicity. Results indicated that 6:2 FTAB could be biodegraded in soil into perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), perfluorobutanoic acid (PFBA) and perfluoropropionic acid (PFPrA). The uptake rate constant (<i>k</i>_u) and the bioaccumulation factor (BAF) of 6:2 FTAB in earthworms were 0.0504 g_oc g_ww⁻¹ d and 1.65 g_oc g_ww⁻¹, respectively. 6:2 FTAB was biotransformed to form PFHxA, PFPeA, PFBA and PFPrA in earthworms after in vivo and in vitro exposure. The aerobic bacteria isolated from worm gut could degrade 6:2 FTAB to form PFPeA and PFHxA, while the anaerobic bacteria did not contribute to 6:2 FTAB biodegradation in worms. Peroxidase (POD) and superoxide dismutase (SOD) activities were significantly increased, while no significant changes were observed for catalase (CAT) activities, demonstrating activation of the primary antioxidant defense system against oxidative stress in earthworms after exposure to 6:2 FTAB. The significant increase of glutathione-S-transferase (GST) activities suggested indirect evidence on the conjugation of 6:2 FTAB or its metabolites in phase II of detoxication. This study provides important information on the fate of 6:2 FTAB in earthworms.

Wenye Li, Wuwei Wu, Quanming Miao et al.

Novel cross-media vehicles can operate efficiently in different media where water entry is a critical process. In this paper, a water–air cross-media unmanned vehicle is designed and its hydrodynamic characteristics during water entry are studied. With the use of STARCCM, the movement of the vehicle during water entry was simulated with the adoption of a VOF multiphase flow model and a Schnerr–Sauer cavitation model and its accuracy was tested. The flow field characteristics of the vehicle under common operating conditions, as well as the influence of the initial water entry speed and angle on the motion state and the force endured by the vehicle under different operating conditions, were simulated. The results show that the overall operating attitude of the vehicle is stable, and the influence of the water entry speed is more significant than that of the water entry angle. The research results provide a theoretical basis and technical support for the design and application of cross-media vehicles, helping to promote cross-media navigation technology.

Haojie Ren, Shixiao Fu, Mengmeng Zhang et al.

A virtual physical system (VPS) for VIV studies of a bluff body is developed to replace the actual physical systems. It can arbitrarily and accurately control and edit the physical parameters, including mass, damping ratio and spring stiffness, specifically for the mass-spring-damper system. The recursive Duhamel integral method (DIM) with unconditional stability was used for the VPS control system, addressing real-time noise filtering problem and simplifying the system as a single input and single output (SISO) one. Delay compensation and inertial force elimination methods were investigated and proposed to overcome the crucial unwanted damping effects. An experimental facility for VIV model tests by VPS was manufactured, and the bluff body model with a measurement system was specially designed to accurately sense the hydrodynamic force during VPS operation. Systematic verification experiments for parameter editing and control of an actual physical target system were conducted, showing that the VPS can reproduce the equivalent spring-damper-mass system in high fidelity with an accuracy error of less than 5 %. VIV model tests for a bluff body at Reynolds numbers (Re= UD/υ, where U is the flow velocity, D represents the diameter of cylinder model, and υ is the kinematic viscosity coefficient) of 5.7E4 and 2.3E5 were performed using the VPS experimental facility, presenting well-Repeated VIV responses at low Re and unexpected VIV response with a large amplitude of 2.4 D at high Re, which can cause severe fatigue damage for relevant structures. The present VPS will provide promising and powerful experimental tools for VIV studies of a bluff body to reveal the related sensitive parameter effects.

Wenwen Jiang, Tingting Liu, Shuting Li et al.

In this study, the distribution patterns of the nitrifying and denitrifying microbiome in a large-scale biofilter (587.24 m³) in a cold freshwater recirculating aquaculture system (RAS) was investigated. Previous studies have revealed that the water quality, nitrification, and denitrification rates in the front (BFF), middle (BFM), and back (BFB) of this biofilter are different. The results showed the highest diversity of the denitrifying microbiome in the BFB, followed by BFF and BFM, whereas nitrifying microbiome diversity remained consistent across different positions. Two genera, <i>Nitrosomonas</i> and <i>Nitrosospira</i>, dominated the nitrifying microbiome, while <i>Pseudomonas</i>, <i>Thauera</i>, <i>Cupriavidus</i>, <i>Dechloromonas</i>, <i>Azoarcus</i>, and <i>Paracoccus</i> comprised the top six denitrifying genera. Principal coordinate analysis indicated a distinct spatial distribution pattern of the denitrifying microbiome but not the nitrifying microbiome. The genera <i>Pseudomonas</i> and <i>Dechloromonas</i> were the biomarkers of the BFF and BFB, respectively. Redundancy analysis showed that nitrite, nitrate, dissolved oxygen, and soluble reactive phosphorus influenced the functional microbiome distribution pattern. Network correlation analysis identified one nitrifying hub (<i>Nitrosospira</i>) in the BFF, five denitrifying hubs (<i>Aromatoleum</i>, <i>Dechloromonas</i>, <i>Paracoccus</i>, <i>Ruegeria</i>, and <i>Thauera</i>) in the BFM, and three denitrifying hubs (<i>Azoarcus</i>, <i>Magnetospirillum</i>, and <i>Thauera</i>) in the BFB. Exclusively negative correlations were found between hubs and its adjacent nodes in the BFF and BFB. This study demonstrates that habitat can shape the distribution patterns of the nitrifying and denitrifying microbiome in the biofilter of the RAS, with the BFF exhibiting greater benefits for the nitrification process.

Shraddha Surana, Ashwin Srinivasan, Michael Bain

Engineering information systems for scientific data analysis presents significant challenges: complex workflows requiring exploration of large solution spaces, close collaboration with domain specialists, and the need for maintainable, interpretable implementations. Traditional manual development is time-consuming, while "No Code" approaches using large language models (LLMs) often produce unreliable systems. We present iProg, a tool implementing Interactive Structured Inductive Programming. iProg employs a variant of a '2-way Intelligibility' communication protocol to constrain collaborative system construction by a human and an LLM. Specifically, given a natural-language description of the overall data analysis task, iProg uses an LLM to first identify an appropriate decomposition of the problem into a declarative representation, expressed as a Data Flow Diagram (DFD). In a second phase, iProg then uses an LLM to generate code for each DFD process. In both stages, human feedback, mediated through the constructs provided by the communication protocol, is used to verify LLMs' outputs. We evaluate iProg extensively on two published scientific collaborations (astrophysics and biochemistry), demonstrating that it is possible to identify appropriate system decompositions and construct end-to-end information systems with better performance, higher code quality, and order-of-magnitude faster development compared to Low Code/No Code alternatives. The tool is available at: https://shraddhasurana.github.io/dhaani/

Shalini Chakraborty, Sebastian Baltes

The IT industry provides supportive pathways such as returnship programs, coding boot camps, and buddy systems for women re-entering their job after a career break. Academia, however, offers limited opportunities to motivate women to return. We propose a diverse multicultural research project investigating the challenges faced by women with software engineering (SE) backgrounds re-entering academia or related research roles after a career break. Career disruptions due to pregnancy, immigration status, or lack of flexible work options can significantly impact women's career progress, creating barriers for returning as lecturers, professors, or senior researchers. Although many companies promote gender diversity policies, such measures are less prominent and often under-recognized within academic institutions. Our goal is to explore the specific challenges women encounter when re-entering academic roles compared to industry roles; to understand the institutional perspective, including a comparative analysis of existing policies and opportunities in different countries for women to return to the field; and finally, to provide recommendations that support transparent hiring practices. The research project will be carried out in multiple universities and in multiple countries to capture the diverse challenges and policies that vary by location.

Mehrzad Zargarzadeh, Adérito J. R. Amaral, C. Custódio et al.

The ocean is par excellence a fertile territory of biodiversity on our planet. Marine-derived polysaccharides have been applied as functional materials in biomedicine due to their attractive bioactive properties, safety, high availability and low-cost production. Laminarin (or laminaran), a low molecular weight β-glucan storage polysaccharide present in brown algae, can be (bio-) chemically modified to enhance its biological activity and employed in cancer therapies, drug/gene delivery, tissue engineering, antioxidant and anti-inflammatory functions. This review provides a brief overview on laminarin characteristics, modification strategies and highlights its pivotal biomedical applications.

赵丹月1，李璐2，陈林2，刘天中2ZHAO Danyue1, LI Lu2, CHEN Lin2, LIU Tianzhong2

为开发亚油酸生产新资源，对筛选获得的一株丝状微藻克里藻，考察培养基氮浓度、培养基磷浓度、光强、培养温度和环境pH对其生长、氮消耗、油脂含量和油脂脂肪酸组成的影响。结果表明：培养基氮浓度对克里藻生长没有明显影响，但高氮不利于油脂和不饱和脂肪酸的合成；培养基磷浓度过低会抑制细胞生长，过高对细胞有毒害作用；适当提高光强有利于细胞生长，但对细胞内油脂含量影响不大，低光强培养有利于亚油酸等不饱和脂肪酸的合成；培养温度对克里藻生长与油脂积累影响不大，低温培养有利于亚油酸的合成；环境pH对细胞生长、油脂积累和亚油酸合成影响明显，pH 6.0~7.5的弱酸-中性条件下细胞生长最快，油脂含量更高；控制初始氮浓度3~6 mmol/L、磷浓度0.115~0.230 mmol/L、光强100~300 μmol/（m2·s)、培养温度15~30 ℃、环境pH 7.5左右，克里藻细胞可积累42%左右的油脂，油脂中亚油酸含量在65%~75%。综上，丝状微藻克里藻是一种有潜力的亚油酸生产新资源。In order to develop new resources for the production of linoleic acid, with a filamentous microalgae Klebsormidium sp. isolated as object, the effect of nitrogen concentration, phosphorus concentration in medium, and light intensity, temperature and environmental pH on the growth, nitrogen consumption, oil content and fatty acid composition of Klebsormidium sp. were investigated. The results showed that nitrogen concentration in the medium did not affect the growth of Klebsormidium sp. , but high nitrogen concentration was detrimental to the synthesis of oil and unsaturated fatty acids. Low phosphorus concentration in the medium inhibited cell growth, while high phosphorus concentration had a toxic effect on cells. Appropriately increasing light intensity was beneficial to cell growth, but had little effect on oil accumulation. More unsaturated fatty acids such as linoleic acid was synthesized under lower light intensity cultivation. Temperature had little effect on the growth and oil accumulation of Klebsormidium sp. , but low temperature was beneficial to the synthesis of linoleic acid. The growth, oil accumulation and linoleic acid content of Klebsormidium sp. were significantly affected by the environmental pH. Cells grew the fastest and had higher oil content in weakly acidic-neutral environments with pH 6.0-7.5. Under the conditions of nitrogen concentration 3-6 mmol/L, phosphorus concentration 0.115-0.230 mmol/L, light intensity 100-300 μmol/(m2·s), temperature 15-30 ℃, environmental pH 7.5, the maximum oil content reached about 42%, of which linoleic acid accounted for 65%-75%. In summary, filamentous microalgae Klebsormidium sp. is a promising new resource for linoleic acid production.

Yingying Wu, Shen Zhang, Jingyi Wang et al.

The primary cause of postharvest loss in table grape fruit is attributed to gray mold, which is caused by <i>Botrytis cinerea</i>. The present study confirmed the inhibitory effects of nystatin on the growth and development of <i>B. cinerea</i>, which led to a remarkable reduction in the severity of gray mold on table grape fruits. Furthermore, the application of nystatin disrupted the membrane permeability of <i>B. cinerea</i>, causing increased cellular leakage and cell death. In addition, the transcriptome analysis showed that the application of nystatin effectively modulated the transcriptional profile of genes involved in ribosome and mitochondrion biogenesis, as well as oxidoreductase activity, thereby disrupting the homeostasis of cellular organelles. Moreover, the nystatin treatment down-regulated genes associated with membrane trafficking, protein degradation by the ubiquitin–proteasome system, and the autophagy process, ultimately attenuating the pathogenicity of <i>B. cinerea</i>. Collectively, nystatin can be considered a viable agent for managing gray mold on table grape fruit.

Jianan Wang, Xueping Cheng, Guiming Jin

Generally, the principle of linear superposition is not applicable in nonlinear systems. The results of our researches prove that for some certain types of decomposed solutions of (2+1)-dimensional Caudrey–Dodd–Gibbon–Kotera–Sawada(CDGKS) equation, the linear superposition principle holds. First, beginning with the potential (2+1)-dimensional CDGKS equation, six sets of decomposition equations are formulated by the formally variable separation approach. On the basis of these decompositions, the linear superposition solutions are then discussed. More specifically, the combination of two periodic wave solutions, soliton and periodic wave interaction solution and the multi-soliton solution are obtained.

Yvonne Dittrich, Johan Bolmsten, Catherine Seidelin

Action research provides the opportunity to explore the usefulness and usability of software engineering methods in industrial settings, and makes it possible to develop methods, tools and techniques with software engineering practitioners. However, as the research moves beyond the observational approach, it requires a different kind of interaction with the software development organisation. This makes action research a challenging endeavour, and it makes it difficult to teach action research through a course that goes beyond explaining the principles. This chapter is intended to support learning and teaching action research, by providing a rich set of examples, and identifying tools that we found helpful in our action research projects. The core of this chapter focusses on our interaction with the participating developers and domain experts, and the organisational setting. This chapter is structured around a set of challenges that reoccurred in the action research projects in which the authors participated. Each section is accompanied by a toolkit that presents related techniques and tools. The exercises are designed to explore the topics, and practise using the tools and techniques presented. We hope the material in this chapter encourages researchers who are new to action research to further explore this promising opportunity.

Nikhil Patnaik, Joseph Hallett, Awais Rashid

Writing secure code is challenging and so it is expected that, following the release of code-generative AI tools, such as ChatGPT and GitHub Copilot, developers will use these tools to perform security tasks and use security APIs. However, is the code generated by ChatGPT secure? How would the everyday software or security engineer be able to tell? As we approach the next decade we expect a greater adoption of code-generative AI tools and to see developers use them to write secure code. In preparation for this, we need to ensure security-by-design. In this paper, we look back in time to Saltzer & Schroeder's security design principles as they will need to evolve and adapt to the challenges that come with a world of AI-generated code.

S. MacKenzie, M. Neveu, A. Davila et al.

Enceladus’s long-lived plume of ice grains and water vapor makes accessing oceanic material readily achievable from orbit (around Saturn or Enceladus) and from the moon’s surface. In preparation for the National Academies of Sciences, Engineering and Medicine 2023–2032 Planetary Science and Astrobiology Decadal Survey, we investigated four architectures capable of collecting and analyzing plume material from orbit and/or on the surface to address the most pressing questions at Enceladus: Is the subsurface ocean inhabited? Why, or why not? Trades specific to these four architectures were studied to allow an evaluation of the science return with respect to investment. The team found that Orbilander, a mission concept that would first orbit and then land on Enceladus, represented the best balance. Orbilander was thus studied at a higher fidelity, including a more detailed science operations plan during both orbital and landed phases, landing site characterization and selection analyses, and landing procedures. The Orbilander mission concept demonstrates that scientifically compelling but resource-conscious Flagship-class missions can be executed in the next decade to search for life at Enceladus.

Lingxiao Zhao, Zhiyang Li, Junsheng Zhang et al.

In recent years, wave energy has gained attention for its sustainability and cleanliness. As one of the most important parameters of wave energy, significant wave height (SWH) is difficult to accurately predict due to complex ocean conditions and the ubiquitous chaotic phenomena in nature. Therefore, this paper proposes an integrated CEEMDAN-LSTM joint model. Traditional computational fluid dynamics (CFD) has a long calculation period and high capital consumption, but artificial intelligence methods have the advantage of high accuracy and fast convergence. CEEMDAN is a commonly used method for digital signal processing in mechanical engineering, but has not yet been used for SWH prediction. It has better performance than the EMD and EEMD and is more suitable for LSTM prediction. In addition, this paper also proposes a novel filter formulation for SWH outliers based on the improved violin-box plot. The final empirical results show that CEEMDAN-LSTM significantly outperforms LSTM for each forecast duration, significantly improving the prediction accuracy. In particular, for a forecast duration of 1 h, CEEMDAN-LSTM has the most significant improvement over LSTM, with 71.91% of RMSE, 68.46% of MAE and 6.80% of NSE, respectively. In summary, our model can improve the real-time scheduling capability for marine engineering maintenance and operations.

C. Santulli, C. Fragassa, A. Pavlović et al.

The term “sea waste” generally refers to any solid, liquid, or gaseous material or substance that is discarded, disposed of, or abandoned in the ocean, sea, or any other body of salty water, such as a lagoon, etc. This includes waste generated by human activities on land that makes its way into the ocean, as well as waste generated by ships and other vessels at sea. Examples of sea waste include plastic debris, chemicals and toxic substances, oil spills, sewage, and other forms of pollution. These pollutants can harm marine ecosystems, endanger marine life, and impact human health and wellbeing. Efforts are being made by governments, organizations, researchers, and individuals to reduce the amount of sea waste generated, and to clean up existing waste in the ocean. Less attention is usually paid to waste materials of natural origin as they are considered (sometimes wrongly) to be less critical; an example is the tons of organic and inorganic material of natural origin that wash up on the beaches daily and must be landfilled or incinerated. The present paper intends to provide an updated review of research experiences and engineering solutions that are able to offer a second life to natural (biological) sea waste by incorporating it into the creation of new, more sustainable materials, and especially composites.

W. Mohammed, Clemente Cesarano, F. M. Al-Askar

In this paper, we consider the (4+1)-dimensional fractional Fokas equation (FFE) with an M-truncated derivative. The extended tanh–coth method and the Jacobi elliptic function method are utilized to attain new hyperbolic, trigonometric, elliptic, and rational fractional solutions. In addition, we generalize some previous results. The acquired solutions are beneficial in analyzing definite intriguing physical phenomena because the FFE equation is crucial for explaining various phenomena in optics, fluid mechanics and ocean engineering. To demonstrate how the M-truncated derivative affects the analytical solutions of the FFE, we simulate our figures in MATLAB and show several 2D and 3D graphs.

Xiyu Chen, Min Zeng, Jianhua Yang et al.

Two-dimensional (2D) phthalocyanine-based covalent organic frameworks (COFs) provide an ideal platform for efficient and rapid gas sensing—this can be attributed to their regular structure, moderate conductivity, and a large number of scalable metal active centers. However, there remains a need to explore structural modification strategies for optimizing the sluggish desorption process caused by the extensive porosity and strong adsorption effect of metal sites. Herein, we reported a 2D bimetallic phthalocyanine-based COF (COF-CuNiPc) as chemiresistive gas sensors that exhibited a high gas-sensing performance to nitrogen dioxide (NO₂). Bimetallic COF-CuNiPc with an asymmetric synergistic effect achieves a fast adsorption/desorption process to NO₂. It is demonstrated that the COF-CuNiPc can detect 50 ppb NO₂ with a recovery time of 7 s assisted by ultraviolet illumination. Compared with single-metal phthalocyanine-based COFs (COF-CuPc and COF-NiPc), the bimetallic structure of COF-CuNiPc can provide a proper band gap to interact with NO₂ gas molecules. The CuNiPc heterometallic active site expands the overlap of <i>d</i>-orbitals, and the optimized electronic arrangement accelerates the adsorption/desorption processes. The concept of a synergistic effect enabled by bimetallic phthalocyanines in this work can provide an innovative direction to design high-performance chemiresistive gas sensors.

Alina Blume, Avi Putri Pertiwi, Chengfa Benjamin Lee et al.

Seagrasses are among the world’s most productive ecosystems due to their vast ‘blue’ carbon sequestration rates and stocks, yet have a largely untapped potential for climate change mitigation and national climate agendas like the Nationally Determined Contributions of the Paris Agreement. To account for the value of seagrasses for these agendas, spatially explicit high-confidence seagrass ecosystem assessments guided by nationally aggregated data are necessary. Modern Earth Observation advances could provide a scalable technological solution to assess the national extent and blue carbon service of seagrass ecosystems. Here, we developed and applied a scalable Earth Observation framework within the Google Earth Engine cloud computing platform to account the national extent, blue carbon stock and sequestration rate of seagrass ecosystems across the shallow waters of The Bahamas—113,037 km2. Our geospatial ecosystem extent accounting was based on big multi-temporal data analytics of over 18,000 10-m Sentinel-2 images acquired between 2017-2021, and deep feature engineering of multi-temporal spectral, color, object-based and textural metrics with Random Forests machine learning classification. The extent accounting was trained and validated using a nationwide reference data synthesis based on human-guided image annotation, recent space-borne benthic habitat maps, and field data collections. Bahamian seagrass carbon stocks and sequestration rates were quantified using region-specific in-situ seagrass blue carbon data. The mapped Bahamian seagrass extent covers an area up to 46,792 km2, translating into a carbon storage of 723 Mg C, and a sequestration rate of 123 Mt CO2 annually. This equals up to 68 times the amount of CO2 emitted by The Bahamas in 2018, potentially rendering the country carbon-neutral. The developed accounts fill a vast mapping blank in the global seagrass map—29% of the global seagrass extent—highlighting the necessity of including their blue carbon fluxes into national climate agendas and showcasing the need for more cost-effective conservation and restoration efforts for their meadows. We envisage that the synergy between our scalable Earth Observation technology and near-future nation-specific in-situ observations can and will support spatially-explicit seagrass and ocean ecosystem accounting, accelerating effective policy-making, blue carbon crediting, and relevant financial investments in and beyond The Bahamas.

Sivakamavalli Jeyachandran, Ramachandran Srinivasan, Thiyagarajan Ramesh et al.

Nanozymes represent a category of nano-biomaterial artificial enzymes distinguished by their remarkable catalytic potency, stability, cost-effectiveness, biocompatibility, and degradability. These attributes position them as premier biomaterials with extensive applicability across medical, industrial, technological, and biological domains. Following the discovery of ferromagnetic nanoparticles with peroxidase-mimicking capabilities, extensive research endeavors have been dedicated to advancing nanozyme utilization. Their capacity to emulate the functions of natural enzymes has captivated researchers, prompting in-depth investigations into their attributes and potential applications. This exploration has yielded insights and innovations in various areas, including detection mechanisms, biosensing techniques, and device development. Nanozymes exhibit diverse compositions, sizes, and forms, resembling molecular entities such as proteins and tissue-based glucose. Their rapid impact on the body necessitates a comprehensive understanding of their intricate interplay. As each day witnesses the emergence of novel methodologies and technologies, the integration of nanozymes continues to surge, promising enhanced comprehension in the times ahead. This review centers on the expansive deployment and advancement of nanozyme materials, encompassing biomedical, biotechnological, and environmental contexts.

Shavindra Wickramathilaka, Ingo Mueller

One of the main reasons that cause seniors to face accessibility barriers when trying to use software applications is that the age-related user interface (UI) needs of seniors (e.g., physical and cognitive limitations) are not properly addressed in software user interfaces. The existing literature proposes model-driven engineering based UI adaptations as a prominent solution for this phenomenon. But in our exploration into the domain, we identified that the existing work lacks comprehensiveness when it comes to integrating accessibility into software modelling tools and methods when compared to a well-recognised accessibility standard such as the Web Content Accessibility Guidelines (WCAG). Thus in this paper, we outline a research roadmap that aims to use WCAG as a reference framework to design domain-specific languages that model the diverse accessibility scenarios of senior users via user context information and UI adaptation rules modelling so that they meet the accessibility standards specified in WCAG.