With the rapid advancement of battery technology, new energy hybrid tugboats have been progressively adopted. In order to align with the trend of electrifying tugboat fleets, a mixed-integer linear programming (MILP) model for the joint scheduling of new energy hybrid tugboats and berths has been established. The model incorporates the constraint imposed by the limited number of tugboat charging connectors. The objective is to minimize the total cost over the scheduling horizon, including ship waiting, delayed-departure costs, and the operating costs of both conventional diesel and hybrid tugboats. In light of the characteristics inherent to the problem, a hybrid solution approach combining CPLEX with a heuristic-enhanced whale optimization algorithm (WOA) is employed to solve the model. A case study was conducted using data on the energy consumption of tugboats at Xiamen Port. The effectiveness of the model and algorithm was then verified through a series of small-scale instance experiments. Finally, a comprehensive sensitivity analysis of key parameters is finally conducted, including the number of tugboat charging connectors, battery capacity, and charging rate. This analysis provides valuable guidance for port tugboat operations.
Abstract Acute pancreatitis (AP) is a disease characterized by an acute inflammatory response in the pancreas. This is caused by the abnormal activation of pancreatic enzymes by a variety of etiologic factors, which results in a localized inflammatory response. The symptoms of this disease include abdominal pain, nausea and vomiting and fever. These symptoms are induced by a hyperinflammatory response and oxidative stress. In recent years, research has focused on developing anti-inflammatory and antioxidative therapies for the treatment of acute pancreatitis (AP). However, there are still limitations to this approach, including poor drug stability, low bioavailability and a short half-life. The advent of nanotechnology has opened up a novel avenue for the management of acute pancreatitis (AP). Nanomaterials can serve as an efficacious vehicle for conventional pharmaceuticals, enhancing their targeting ability, improving bioavailability and prolonging their half-life. Moreover, they can also exert a direct therapeutic effect. This review begins by introducing the general situation of acute pancreatitis (AP). It then discusses the pathogenesis of acute pancreatitis (AP) and the current status of treatment. Finally, it considers the literature related to the treatment of acute pancreatitis (AP) by nanomaterials. The objective of this study is to provide a comprehensive review of the existing literature on the use of nanomaterials in the treatment of acute pancreatitis (AP). In particular, the changes in inflammatory markers and therapeutic outcomes following the administration of nanomaterials are examined. This is done with the intention of offering insights that can inform subsequent research and facilitate the clinical application of nanomaterials in the management of acute pancreatitis (AP). Graphical Abstract
The presence of sea ice threatens low ice-class vessels’ navigation safety in the Arctic, and traditional Navigation Risk Assessment Models based on sea ice parameters have been widely used to guide safe passages for ships operating in ice regions. However, these models mainly rely on empirical coefficients, and the accuracy of these models in identifying sea ice navigation risk remains insufficiently validated. Therefore, under the binary classification framework, this study used Automatic Identification System (AIS) data along the Northeast Passage (NEP) as positive samples, manual interpretation non-navigable data as negative samples, a total of 10 machine learning (ML) models were employed to capture the complex relationships between ice conditions and navigation risk for Polar Class (PC) 6 and Open Water (OW) vessels. The results showed that compared to traditional Navigation Risk Assessment Models, most of the 10 ML models exhibited significantly improved classification accuracy, which was especially pronounced when classifying samples of PC6 vessel. This study also revealed that the navigability of the East Siberian Sea (ESS) and the Vilkitsky Strait along the NEP is relatively poor, particularly during the month when sea ice melts and reforms, requiring special attention. The navigation risk output by ML models is strongly determined by sea ice thickness. These findings offer valuable insights for enhancing the safety and efficiency of Arctic maritime transport.
Under global warming, persistent extreme heat events (PHEs) in China have increased significantly in both frequency and intensity, posing severe threats to agriculture and socioeconomic development. Combining observational analysis (1961–2019) and numerical simulations, this study investigates the distinct impacts of Northwest Pacific (NWP) and North Atlantic (NA) sea surface temperature (SST) anomalies on PHEs over China. Key findings include the following: (1) PHEs exhibit heterogeneous spatial distribution, with the Yangtze-Huai River Valley as the hotspot showing the highest frequency and intensity. A regime shift occurred post-2000, marked by a threefold increase in extreme indices (+3σ to +4σ). (2) Observational analyses reveal significant but independent correlations between PHEs and SST anomalies in the tropical NWP and mid-high latitude NA. (3) Numerical experiments demonstrate that NWP warming triggers a meridional dipole response (warming in southern China vs. cooling in the north) via the Pacific–Japan teleconnection pattern, characterized by an eastward-retreated and southward-shifted sub-tropical high (WPSH) coupled with an intensified South Asian High (SAH). In contrast, NA warming induces uniform warming across eastern China through a Eurasian Rossby wave train that modulates the WPSH northward. (4) Thermodynamically, NWP forcing dominates via asymmetric vertical motion and advection processes, while NA forcing primarily enhances large-scale subsidence and shortwave radiation. This study elucidates region-specific oceanic drivers of extreme heat, advancing mechanistic understanding for improved heatwave predictability.
This paper showcases a data-driven non-linear adaptive controller design employing an unfalsification approach to attain optimal estimates for unknown parameters in an autonomous underwater vehicle (AUV). These estimates are applied to the controller to enable precise trajectory tracking. The controller design presented is capable of adapting to parametric changes and uncertainties while fulfilling the desired performance criteria using an effective parameter update method of unfalsification. The results were validated through simulations conducted using MATLAB/SIMULINK.
In order to investigate the evolution of pore structures in cementitious materials, a statistical model is proposed by taking the cement paste as a random dispersion system of two-phase medium. Simultaneously, the μic platform is employed to simulate the cement hydration. The results obtained from the simulation and the disperse models are compared with each other, and further analysis on calculation conditions and parameters of the disperse models are conducted. The pore size distribution obtained from polydisperse hard sphere model is very close to the simulation in completely dispersion condition. Taking into account the cross and agglomeration effects of hydrated products, the calculation results of the monodisperse concentric-shell model are more consistent to the simulations. Considering the flocculation of cement particles in initial state, the monodisperse hard model is closer to the simulation results. This paper offers a new insight from the viewpoints of mathematics and physics to understand and describe the pore structures of cementitious materials.
Engineering (General). Civil engineering (General), Chemical engineering
The safety assessment of ship cargo securing systems is of significant importance in preventing casualties, vessel instability, and economic losses resulting from the failure of securing systems during transportation in adverse sea conditions. In this study, an independently designed cylindrical cargo securing scheme with supporting structures was adopted for investigation. Utilizing a sway device, three-degree-of-freedom coupled motion encountered during ship transportation was obtained, and data regarding changes in the support forces at the foundations and tension forces in the lashing ropes were collected. Subsequently, numerical simulations were conducted using the multibody dynamics software ADAMS 2020. The results obtained from the simulations were compared with the experimental data. The overall tendencies were accurately predicted in the numerical analysis. It was observed that the difference of the peak support forces between the numerical simulation results and the experimental data were within a 10% margin. In terms of the lashing ropes, the difference was limited, within 9%. These findings demonstrate that numerical simulation techniques can provide valuable insights for verifying the safety of practical cargo securing systems.
Charalampos Nikolaos Roukounis, Vasiliki K. Tsoukala, Vassilios A. Tsihrintzis
The aim of this study is to assess the resilience of coastal urban areas and their exposure to sea-level rise and coastal flooding, using the proposed Coastal Resilience Index (CResI). The CResI is an innovative combination of diverse characteristics. It includes 19 parameters and is implemented using GIS techniques. The parameters included in the CResI are classified into six category factors (geomorphology, flooding, wave exposition, land use, socioeconomic, and infrastructure/functional). The Analytic Hierarchy Process is used to assign weights and rank the parameters. The framework is tested in the southwest waterfront of the Athens Metropolitan Area in Greece. The study identified that around 25% of the coastal area could be at risk of coastal flooding in the upcoming years, including areas in both the metropolitan and suburban environments. As a result, the need for adaptation measures cannot be overlooked.
To obtain the mechanical energy of waves from arbitrary directions, the vibration absorbers of wave energy converters (WEC) are usually vertically axisymmetric. In such case, the wave-body interaction hydrodynamics is an essential research topic to obtain high-efficiency wave energy. In this paper, a semi-analytical method of decomposing the complex axisymmetric boundary into several ring-shaped stepped surfaces based upon the boundary approximation method (BAM) is introduced and examined. The hydrodynamic loads and parameters, such as the wave excitation forces, added mass and radiation damping of the vertical axisymmetric oscillating buoys, can then be achieved by using the new boundary discretisation method. The calculations of the wave forces and hydrodynamic coefficients show good convergence with the number of discretisation increases. Comparison between the constringent results and the results of the conventional method also verifies the feasibility of the method. Then, simulations and comparisons of the hydrodynamic forces, motions and wave power conversions of the buoys with series draught and displacement ratios in regular and irregular waves are conducted. The calculation results show that the geometrical shape has a great effect on the hydrodynamic and wave power conversion performance of the absorber. In regular waves, though the concave buoy has the lowest wave conversion efficiency, it has the largest frequency bandwidth for a given draught ratio, while in irregular waves, for a given draught ratio, the truncated cylindrical buoy has the best wave power conversion, and for a given displacement of the buoy, the concave buoy shows the best wave power conversion ability.
Alessandro Zambon, Lorenzo Moro, Jeffrey Brown
et al.
Polar navigation entails challenges that affect the continuation of ship operations in severe ice conditions. Due to ice-propeller interaction, propulsion shafting segments are often at a high risk of failure. Efficient methods for shaft line design are hence needed to ensure the safety of ice-going vessels and propulsion reliability. To this end, full-scale measurements have proven essential to support the development of ship-design tools and updated safety regulations for ice-going vessels. This paper presents a unique integrated measurement system that employs measuring equipment to monitor Polar-Class vessel performance and shaft line dynamics during ice navigation. The system was installed on board the Canadian Coast Guard (CCG) icebreaker Henry Larsen. This experimental concept aims to monitor the shaft’s torque and thrust fluctuations during ice navigation to obtain information about the ship’s propulsion efficiency. In the paper, we describe the arrangement of the measurement system and the components it features. Finally, we present preliminary datasets acquired during two icebreaking expeditions. This work is framed into a broader research project, which includes the long-term objective to determine a correlation between sea ice conditions and the dynamic response of shaft lines.
AbstractWe develop a robust queueing network analyzer algorithm to approximate the steady‐state performance of a single‐class open queueing network of single‐server queues with Markovian routing. The algorithm allows nonrenewal external arrival processes, general service‐time distributions and customer feedback. The algorithm is based on a decomposition approximation, where each flow is partially characterized by its rate and a continuous function that measures the stochastic variability over time. This function is a scaled version of the variance‐time curve, called the index of dispersion for counts (IDC). The required IDC functions for the external arrival processes can be calculated from the model primitives or estimated from data. Approximations for the IDC functions of the internal flows are calculated by solving a set of linear equations. The theoretical basis is provided by heavy‐traffic limits for the flows established in our previous papers. A robust queueing technique is used to generate approximations of the mean steady‐state performance at each queue from the IDC of the total arrival flow and the service specification at that queue. The algorithm's effectiveness is supported by extensive simulation studies.
Iosif Progoulakis, Nikitas Nikitakos, Paul Rohmeyer
et al.
In an ever-evolving technological industry, the oil and gas sector is already moving forward through the adaptation of Industry 4.0 and the adaptation of advanced cyber technologies through Oil and Gas 4.0. As IT/OT (information technology/operational technology) systems are evolving technologically, so are the cyber security threats faced by the offshore oil and gas assets. This paper aims to raise the awareness of cyber security threats and the organizational and technical measures that need to be adopted by the oil and gas industry for remote and complex assets in the upstream sector. A comprehensive literature review covering the areas of new IT/OT systems integration and cyber security risk analysis and management is presented. The results of a survey on the subject of cyber security for offshore oil and gas assets are also presented, and they provide valuable insight into the current industry culture and the perception of cyber security concepts. The importance of organizational culture, personnel training and involvement, as well as corporate engagement and support in the subject of cyber security is highlighted.
Temperature is a key variable to evaluate the energy consumption and thermodynamic performance of traditional marine auxiliary machinery, chillers and piping systems. In particular, for the cryogenic storage tanks and fuel gas supply systems of LNG ships, explosion-proof and low-temperature-resistance properties bring new challenges to the onboard temperature measurement and monitoring. In order to promote the development of high-performance and safer monitoring systems for LNG ships, this paper adopted fiber Bragg grating (FBG) technology to ensure the measurement safety and accuracy of temperature sensors, and performs a series of experiments in a large temperature range on the chiller, pipeline, and cryogenic storage tank of an LNG ship and their long-term reliabilities. Firstly, the principle and composition of the designed FBG temperature sensors are introduced in detail, and the measurement accuracy and range of different metal-coated optical fibers were tested in a large temperature range and compared against the traditional thermistors. Then, the effects of different operating conditions of the LNG marine chiller system and cryogenic storage tank on the temperature measurements were investigated. In addition, the drift degrees of the optical fibers and industrial thermistors were analyzed to figure out their reliabilities for long-term temperature measurements. The results showed that for the long-period (16 months) monitoring of LNG ships in a large temperature range (105–315 K) under different shipping conditions, the optical temperature measurement based on FBG technology has sufficient accuracy and dynamic sensitivity with a higher safety than the traditional thermoelectric measurement. Besides, the ship vibration, ambient humidity, and great temperature changes have little impact on its measurement reliability and drifts. This research can provide references and technical supports to the performance testing systems of LNG ships and other relevant vessels with stricter safety standards.
Ognjen Bonacci, Duje Bonacci, Matko Patekar
et al.
The Adriatic Sea and its coastal region have experienced significant environmental changes in recent decades, aggravated by climate change. The most prominent effects of climate change (namely, an increase in sea surface and air temperature together with changes in the precipitation regime) could have an adverse effect on social and environmental processes. In this study, we analyzed the time series of sea surface temperature and air temperature measured at three meteorological stations in the Croatian part of the Adriatic Sea. To assess the trends and variations in the time series of sea surface and air temperature, different statistical methods were employed, i.e., linear and quadratic regressions, Mann–Kendall test, Rescaled Adjusted Partial Sums method, and autocorrelation. The results evidenced increasing trends in the mean annual sea surface temperature and air temperature; furthermore, sudden variations in values were observed in 1998 and 1992, respectively. Increasing trends in the mean monthly sea surface temperature and air temperature occurred in the warmer parts of the year (from March to August). The results of this study could provide a foundation for stakeholders, decision–makers, and other scientists for developing effective measures to mitigate the negative effects of climate change in the scattered environment of the Adriatic islands and coastal region.
Beatrice Fenu, Valentino Attanasio, Pietro Casalone
et al.
The energy innovation scenario sees hybrid wind-wave platforms as a promising technology for reducing the variability of the power output and for the minimization of the cost of offshore marine renewable installations. This article presents a model that describes the installation of a 5 MW wind turbine on a floating platform designed by Fincantieri and equipped with gyroscopic stabilization. The use of gyros allows for the delivery of platform stabilization by damping the wave and wind induced motion on the floater and at the same time producing extra power. Shetland Island was chosen as the reference site because of its particularly harsh weather. Final results show that the total production of power in moderate and medium climate conditions is considerable thanks to the installation of the gyro, together with a significant stabilization of the platform in terms of pitching angle and nacelle acceleration.
Vikram S Grewal, Kuntal Bandyopdhyay, Punita A Sharma
et al.
Background: A concerted effort has been made by the Government of India and the Armed Forces to train all health-care workers (HCWs) in various aspects of the prevention and management of COVID-19. This study was conducted to evaluate the efforts by assessing their knowledge, attitudes, practice, and behavior regarding COVID-19. Materials and Methods: A quick online survey, using a web portal and social media platform with a pretested questionnaire, was conducted. Responses were collected for 3 days and analyzed. Results: A total of 988 HCWs participated, including 61 (6.17%) specialist officers, 98 (9.91%) medical officers, 17 (1.72%) dental officers, 135 (13.66%) nursing officers, 518 (52.4%) paramedical staff, and 159 (16.09%) supporting staff. There was a high prevalence (>90%) of knowledge related to symptoms and transmission of the disease with no statistically significant difference in knowledge based on the category of HCW except for bleaching powder requirement (0.001) and chemoprophylaxis (0.001). The majority of the participants (>95%) agreed that lockdown, infection control programs, and repeated training of HCWs are good measures to control COVID-19 spread. Observing full precaution while handling personal protective equipment was the only practice which demonstrated a significant association with increasing qualification of the participant (P < 0.001). Conclusions: Levels of knowledge, positive attitude, and good practices are high among HCWs in the Armed Forces, however, feeling of anxiousness and worry prevail being frontline workers with maximum proximity toward patients. Aggressive, continuous, relevant target population-oriented information, education, and communication is the need of the hour, with structured and programmed interventions for positive mental health during course of the pandemic.
Toshio Yamazu, Koshi Haraguchi, Takahiko Inoue
et al.
We have developed new a deep-towed seismic streamer for sub-bottom profiling. To obtain a high-resolution seismic signal, this streamer can be operated at depths of up to 2000 m, and state-of-the-art technology is adopted with electronics circuits, that can withstand high pressures of up to 22 MPa. The streamer houses an ultra-low noise pre-amplifier, micro-processor, AD convertor, high precision clock, gain controller, and other circuitry in an oil-filled vessel. The high S/N ratio gives us high-resolution seismic images. The streamer comprises several catenated single modules and the recorded acoustic data are transmitted to the control computer with the Ethernet protocol. This makes the length of the streamer cable, and the number of hydrophones, flexible. For instance, we can use both single-channel and multi-channel streamers in the same system. Up to 24-channels can be catenated.
The paper deals with sensitivity and reliability applications to numerical studies of an off-shore platform model. Structural parameters and sea conditions are referred to the Baltic jack-up drilling platform. The sudy aims at the influence of particular basic variables on static and dynamic response as well as the probability of failure due to water waves and wind loads. The paper presents the sensitivity approach to a generalized eigenvalue problem and evaluation of the performace functions. The first order time-invariant problems of structural reliability analysis are under concern.
Bu çalışmada, Karadeniz tipi bir balıkçı teknesinin üretim süreci detaylı olarak incelenmiş ve SİMİO simülasyon tabanında bir modeli oluşturulmuştur. Oluşturulan bu model ile Karadeniz tipi balıkçı teknesinin üretim süresi belirlenmiştir. Sonra, tekne imalatında çalışma saatleri değiştirilmek suretiyle teknenin imalat süresi belirlenmiş ve bu şekilde çalışma saatlerinin tekne üretim süresine olan etkileri incelenmiştir. Sonuç olarak, çalışma süresindeki her artışın tekne üretim süresini etkilemediği gözlemlenmiş ve çalışma saatlerindeki düzenli artışların Karadeniz tipi teknenin üretim süresi üzerine etkileri sayısal olarak ortaya konulmuştur.