Excessive cargo sway during crane operations in the current shipbuilding industry is a major problem that causes safety accidents and work delays. Therefore, the development of stable crane control technology is essential. In this study, a crane control algorithm that simultaneously achieves accurate movement to target positions and sway minimization was developed using reinforcement learning. In dynamics modeling, the Discrete Euler-Lagrange Equation was applied to significantly reduce the computational complexity of existing methods, and the Proximal Policy Optimization (PPO) method was used for control policy learning. A three-dimensional virtual environment was constructed to perform learning under various travel distances and operating conditions, and the performance of the developed algorithm was compared and verified against the traditional trapezoidal velocity profile. Experimental results showed that the proposed method exhibited significant improvements in position control precision and sway suppression performance compared to existing methods. The results of this study are expected to contribute to the implementation of automated crane control systems in actual shipyard environments.
LU Zhan, WANG Jian, MA Qingyan, XU Changjian, LIANG Xiaofeng
Thrust allocation serves as a critical means for achieving vector propulsion in unmanned surface vessels (USV) equipped with dual waterjet thrusters. However, existing thrust allocation methods employed in vessels featuring azimuth thrusters fail to address the resolution of vector forces for dual waterjet propulsion, due to characteristics such as thrust angle limitations and reverse thrust. To achieve vector motion control of a dual waterjet propelled USV, a hierarchical optimization-based thrust allocation algorithm is proposed. In the first tier, a vector synthesis approach incorporating enhanced angle constraints is utilized to acquire top-tier vector thrust satisfying constraints on the rotating range and rate characteristics of the thrusters. In the second tier, leveraging the top-tier vector thrust values as inputs and considering constraints on thruster power and power change frequency, an optimization method based on seeking minimal distance is proposed. This method facilitates the allocation of reverse thrust angles and nozzle flow velocities for waterjet thrusters, thereby resolving singular issues in dual waterjet thrust allocation. Simulation experiments and the semi-physical simulation experiments validate the effectiveness of the hierarchical optimization-based thrust allocation algorithm for dual waterjet thrusters. The results indicate that this method enables efficient thrust allocation for dual waterjet thrusters, while concurrently limiting fluctuations in thruster power frequency and amplitude during expected thrust variations, thereby reducing shafting wear while achieving target vector thrust.
Engineering (General). Civil engineering (General), Chemical engineering
ABSTRACT A mission may be aborted during operation to increase the likelihood of system survival when an alarm system indicates that the system has entered a defect state. However, due to measurement and environmental noise, missed and false alarms frequently occur during online condition monitoring, complicating the decision‐making process for mission abort. Additionally, once a mission is aborted, various rescue procedures can be initiated. This study addresses these challenges by proposing a partially observable Markov decision process (POMDP) framework aimed at minimizing the expected total cost associated with mission and system failures. Within this framework, the probability that the system is in a defect state is dynamically updated using real‐time signals from the alarm system. We demonstrate that the optimal mission abort policy follows a control limit policy, where a mission should be aborted when the defect probability exceeds a certain threshold during each period. To illustrate the effectiveness of the proposed policy, we present a case study on an unmanned aerial vehicle (UAV).
<p><strong>Purpose:</strong> This study aims to examine the relationship between gender-responsive governance and conflict management practices, with a focus on how school leaders handle conflicts across various domains—competing, collaborating, compromising, avoiding, and accommodating. The analysis considers the key variables, including age, gender, length of service, and educational attainment. Based on the findings, a Gender-Responsive Governance and Conflict Management Practices Enhancement Training Program will be designed to address identified gaps and challenges effectively.</p><p><strong> </strong></p><p><strong>Methods:</strong> This study utilized a descriptive-correlational research design with a quantitative approach to examine gender-responsive governance and conflict management practices among selected Maritime Higher Education Institutions (MHEIs) in the Philippines. A total of 73 school leaders from various MHEIs participated in the study. Data were collected using two questionnaires: the first, based on the Gender Responsiveness Governance Tool developed by USAID, assessed the level of gender-responsive governance; the second, adapted from the Thomas-Kilmann Conflict Mode Instrument (TKI), evaluated the conflict management practices of the respondents. The data were analysed using statistical methods, including mean, standard deviation, t-test for independent samples, One-Way Analysis of Variance (ANOVA), and Pearson’s correlation coefficient (r).</p><p> </p><p><strong>Findings:</strong> Results revealed that respondent’ level of gender-responsive governance according to age, gender, length of service, educational qualification, and management level was “high.” Generally, the topmost management practice of the respondents was collaborating except those respondents with shorter length of service (adopted compromising style); those with bachelor’s degree (adopted compromising style); and those with doctorate degree (adopted competing style). Statistically, no significant difference existed in the level of gender-responsive governance of the respondents when grouped and compared according to age, gender, length of service, educational qualification, and management level. Moreover, result showed a significant but weak to moderate degree of relationship between gender-responsive governance and conflict management practices of the respondents. In other words, respondents’ gender-responsive governance was, to some degree, reflective of their conflict management practices.</p><p><strong>Research Implications:</strong> The findings of this study underscore the importance of gender-responsive governance and its integration with conflict management practices in organizations. Despite no statistically significant differences based on demographic characteristics such as age, gender, length of service, educational qualification, and management level, the study highlights that a strong commitment to gender equality is a pervasive feature across diverse respondent groups. This suggests that gender-responsive governance principles are universally embraced by management, regardless of these variables. Besides, finding implies that fostering a gender-responsive environment may enhance the effectiveness of conflict resolution strategies, as inclusive decision-making processes that prioritize collaboration and fairness are more likely to lead to positive outcomes. Future research could explore deeper into how various conflict management styles, particularly the collaborating style, influence gender equality and fairness in the workplace. Additionally, further investigation could examine how specific demographic factors—such as length of service or educational qualifications—may influence the adoption of particular conflict management styles, even when their effect on gender-responsive governance appears neutral.</p><p><strong>Practical Implications:</strong> Practically, the findings suggest that organizations can benefit from promoting gender-responsive governance practices across all management levels, as these practices contribute to creating an inclusive, fair, and equitable workplace. The strong preference for collaborative conflict management among respondents indicates that encouraging open, inclusive dialogue can resolve workplace conflicts more effectively, which is particularly important in diverse work environments where gender equality is a priority. Organizations could consider training programs that emphasize both gender-responsive governance and collaborative conflict resolution techniques. Such programs would help leaders develop the skills necessary to address conflicts with a mindset that prioritizes fairness and inclusivity, benefiting both men and women in the workplace. Furthermore, even though no significant differences were observed in relation to respondents' personal characteristics, understanding how demographic factors might influence management practices could assist in tailoring strategies to address potential barriers to achieving gender equality and conflict resolution in the workplace. Incorporating these insights into organizational practices will not only foster better conflict management but also enhance overall workplace harmony, leading to improved employee satisfaction and retention.</p><p> </p><p><strong>Received on: 28 November 2024 </strong></p><p><strong>Accepted on: 22 February 2025 </strong></p><p><strong>Published on: 13 March 2025</strong></p>
Ship Shoal, a large transgressive sand body on the Louisiana continental shelf, is a critical sediment source for coastal restoration. This study evaluates spatial and temporal variability in sediment grain size, percents organic matter (%OM), and carbonate (%CO<sub>3</sub>) across the shoal crest (REF), Caminada Dredge Pit (CAM), and Terrebonne Dredge Pit (TER). Sediment samples were collected between 2020 and 2022 using box cores and analyzed for grain size, %OM, and %CO<sub>3</sub>, with temporal and spatial patterns assessed through statistical comparisons, correlation analyses, and random forest regression models. Results show that dredged areas act as sinks for fine-grained, organic-rich sediments, with CAM consistently exhibiting the smallest median grain sizes and highest %OM, while REF maintained coarse, well-sorted sands. Carbonate enrichment reflected long-term depositional regimes, with REF exhibiting the highest %CO<sub>3</sub> due to the absence of dredging disturbance. Grain size and %CO<sub>3</sub> were identified as the strongest predictors of %OM, while %CO<sub>3</sub> was only weakly correlated with other sedimentary variables. Collectively, these findings demonstrate that dredge pits function as persistent repositories, with implications for benthic habitat resilience, sediment management, and coastal restoration planning. Future integration of hydrodynamic modeling with sediment transport and biogeochemical processes is needed to enhance predictive capability for managing dredged environments.
This experimental study investigates the effectiveness of the Cognitive Conflict-Based Generative Learning Model (GLBCC) in enhancing science literacy among high school physics students. The novelty of this research lies in the innovative integration of cognitive conflict strategies with generative learning principles through a six stage structured framework, specifically designed to address persistent misconceptions in physics education while systematically developing scientific literacy competencies. The research employed pretest-posttest control group design involving 167 Grade XI students from three schools. Students were randomly assigned to experimental groups (n = 83) that received GLBCC instruction and control groups (n = 84) that used the expository learning model. Science literacy was measured using validated instruments assessing scientific knowledge, inquiry processes, and application skills across six key indicators. Statistical analysis using ANOVA with Tukey HSD post-hoc tests revealed significant improvements in science literacy scores for students receiving GLBCC instruction compared to traditional methods (p < 0.001). This study makes a unique contribution to physics education by demonstrating how the deliberate creation of cognitive conflict, combined with authentic real-world physics phenomena, can effectively restructure students conceptual understanding and enhance their scientific thinking capabilities. Factor analysis identified four critical implementation factors: science literacy development components, learning stages and orientation, and objectives, and knowledge construction processes. The findings provide empirical evidence supporting the integration of cognitive conflict strategies with generative learning approaches in physics education, offering practical implications
K. Larsen, R. Lukyanenko, Roland M. Mueller
et al.
Researchers must ensure that the claims about the knowledge produced by their work are valid. However, validity is neither well-understood nor consistently established in design science, which involves the development and evaluation of artifacts (models, methods, instantiations, and theories) to solve problems. As a result, it is challenging to demonstrate and communicate the validity of knowledge claims about artifacts. This paper defines validity in design science and derives the Design Science Validity Framework and a process model for applying it. The framework comprises three high-level claim and validity types-criterion, causal, and context-as well as validity subtypes. The framework guides researchers in integrating validity considerations into projects employing design science and contributes to the growing body of research on design science methodology. It also provides a systematic way to articulate and validate the knowledge claims of design science projects. We apply the framework to examples from existing research and then use it to demonstrate the validity of knowledge claims about the framework itself.
ABSTRACT We investigate the scheduling problem on parallel and identical machines under periodic availability constraints. Availability periods and unavailability periods appear alternately on each machine. We propose an algorithm, PFFD, and demonstrate that its worst‐case ratio is at most for , where represents the ratio of the duration of an unavailability period to an availability period. Furthermore, we develop the PPTAS algorithm, which can achieve a worst‐case ratio arbitrarily close to and runs in polynomial time when is a constant. When is part of the input, we show that there does not exist a polynomial time algorithm with worst‐case ratio better than unless .
Introduction: Benign prostatic hyperplasia is a common condition in elderly men and is a major cause of bladder outflow obstruction. Various parameters are used in clinical practice, to be able to assess the severity of the enlarged prostate and its direct effect on the quality of life of the patient in terms of evaluation of lower urinary tract symptoms (LUTSs). These are the International Prostate Symptom Score (IPSS); urodynamic studies such as uroflowmetry, measurement of postvoid residual urine (PVRU), prostatic volume (PV), intravesical prostatic protrusion, and digital rectal examination. Out of these, sonographic measurement of prostate volume and postvoid residual urine is the most widely used and readily available noninvasive methods. The present hospital-based study aims to establish an association between the PV, PVRU, and clinical symptom scores derived as per IPSS. Methods: This prospective, hospital-based study was done over a sample group of 748 symptomatic males with LUTS, referred from outpatient departments over a period of 2 years, for the assessment of PV and postvoid residual urine. The ordinal data sets were compared using the Chi-square test and a P < 0.05 was taken as statistically significant. Results: The Chi-square statistics for the association of prostate volume with IPSS were 13.1678. P value was = 0.01. The Chi-square statistics for the association between PVRU and IPSS scores were 1.613. P value was = 0.80645. Conclusion: The results derived from the data establish that the statistical association between prostate volume and IPSS scores is weakly significant and association between PVRU and IPSS scores is not statistically significant at all.
Background:
Allergic rhinitis (AR) is implicated in the pathogenesis of Eustachian tube dysfunction (ETD). Its sequelae cause burgeoning of several middle ear diseases. Testing of ETD is a diagnostic challenge and requires objective methods of assessment.
Materials and Methods:
In our prospective observational study, 402 patients with AR were grouped into mild and moderate to severe AR. Nasal endoscopy, tympanometry, and Williams test were used for objective assessment of ETD. The severity and laterality of ETD were assessed and the prevalence of the same was calculated.
Statistical Analysis:
The graphical tabulation of data was prepared using MS Excel 2010. Unpaired t-test was used to compare the study groups and the association among the groups was extracted with the help of Fisher’s test and Chi-square test. P < 0.05 was considered significant.
Results:
Mild AR was found in 44.5% of cases, while moderate to severe AR was seen in 55.5% of cases. 38.1% of cases of AR had ETD, out of which significant population (28.6%) had bilateral involvement. The dysfunction was partial or complete in 22.2% and 15.9% patients, respectively. 38.6% of patients had a type C curve on tympanometry in patients with AR and the rest had type A curve.
Conclusions:
AR patients have a higher propensity to develop bilateral ETD. The patients having moderate to severe AR have more ETD. A tympanometry will only provide information regarding ETD, whether present or absent, whereas ET function tests such as Williams test provide information regarding the functionality of ET and severity of ETD. It is recommended that all newly diagnosed cases of AR should be evaluated for ETD and be followed up regularly.
When an airborne sound source is in rapid motion, the acoustic signal detected by the underwater sensor experiences a substantial Doppler shift. This shift is intricately linked to the motion parameters of the sound source. Analyzing the Doppler shift characteristics of received acoustic signals enables not only the estimation of target motion parameters but also the localization of the airborne sound source. Currently, the predominant methods for estimating parameters of uniformly moving targets are grounded in classical approaches. In this study, the application of the Doppler warping transform, traditionally applicable to sound sources in uniform linear motion, is extended to encompass a broader spectrum of sound source trajectories. Theoretical and experimental data validate the efficacy of this transform in linearizing the Doppler shift induced by a source in curved motion. Building upon this foundation, a methodology is proposed for locating airborne acoustic sources in curved motion from underwater. Sea experimental data corroborate the method’s effectiveness in achieving underwater localization of a helicopter target during curved motion.
In the era of data-driven decision-making, the complexity of data analysis necessitates advanced expertise and tools of data science, presenting significant challenges even for specialists. Large Language Models (LLMs) have emerged as promising aids as data science agents, assisting humans in data analysis and processing. Yet their practical efficacy remains constrained by the varied demands of real-world applications and complicated analytical process. In this paper, we introduce DSEval -- a novel evaluation paradigm, as well as a series of innovative benchmarks tailored for assessing the performance of these agents throughout the entire data science lifecycle. Incorporating a novel bootstrapped annotation method, we streamline dataset preparation, improve the evaluation coverage, and expand benchmarking comprehensiveness. Our findings uncover prevalent obstacles and provide critical insights to inform future advancements in the field.
The emergence of specialized large language models (LLMs) has shown promise in addressing complex tasks for materials science. Many LLMs, however, often struggle with distinct complexities of material science tasks, such as materials science computational tasks, and often rely heavily on outdated implicit knowledge, leading to inaccuracies and hallucinations. To address these challenges, we introduce HoneyComb, the first LLM-based agent system specifically designed for materials science. HoneyComb leverages a novel, high-quality materials science knowledge base (MatSciKB) and a sophisticated tool hub (ToolHub) to enhance its reasoning and computational capabilities tailored to materials science. MatSciKB is a curated, structured knowledge collection based on reliable literature, while ToolHub employs an Inductive Tool Construction method to generate, decompose, and refine API tools for materials science. Additionally, HoneyComb leverages a retriever module that adaptively selects the appropriate knowledge source or tools for specific tasks, thereby ensuring accuracy and relevance. Our results demonstrate that HoneyComb significantly outperforms baseline models across various tasks in materials science, effectively bridging the gap between current LLM capabilities and the specialized needs of this domain. Furthermore, our adaptable framework can be easily extended to other scientific domains, highlighting its potential for broad applicability in advancing scientific research and applications.
Brian G. Sanderson, Richard H. Karsten, Daniel J. Hasselman
An area has been designated for demonstrating the utility of marine hydrokinetic turbines in Minas Passage, Bay of Fundy. Marine renewable energy may be useful for the transition from carbon-based energy sources, but there is concern for the safety of fish that might encounter turbines. Acoustic receivers that detect signals from acoustically tagged fish that pass through the tidal demonstration area and the detection efficiency of tag signals might be used to estimate the likelihood of fish encountering marine hydrokinetic turbines. The method requires that tagged fish passing through the development area will be reliably detected by a receiver array. The present research tests the reliability with which passing tags are detected by suspending tags beneath GPS-tracked drifters. Drifters carrying high residency Innovasea tags that transmitted every 2 s were usually detected by the receiver array even in fast currents during spring tides but pulse-position modulation tags were inadequate. Sometimes very few high residency tag signals were detected when fast tidal currents swept a drifter through the receiver array, so increasing the transmission interval degrades performance at the tidal energy development area. High residency tags suspended close to the sea surface were slightly less likely to be detected if they passed by during calm conditions. Previously measured detection efficiencies were found to slightly overestimate the chances of a high residency tag carried by a drifter being detected as it passed by a receiver. This works elucidates the effectiveness with which acoustically tagged fish are detected in fast, highly turbulent tidal currents and informs the application of detection efficiency measurements to calculate the probability that fish encounter a marine hydrokinetic turbine.
The path planning of unmanned ships in complex waters using heuristics usually suffers from problems such as being prone to fall into the local optimum, slow convergence, and instability in global path planning. Given this, this paper proposes a Self-Adaptive Hybrid Bald Eagle Search (SAHBES) Algorithm by incorporating adaptive factors into the traditional BES in order to enhance the early global searching ability of the BES algorithm. Moreover, Pigeon-Inspired Optimization (PIO) is introduced to overcome the disadvantage of traditional BES algorithms: that it is easy for them to fall into local optimization. This study improves the fitness function by adding a distance between the ships’ path corners. The obstacle is based on the calculation of the path length. The curve optimization module is applied to smooth the obtained path to generate more rational path planning results, which means the path is the shortest and avoids collision successfully. A simulation test of the SAHBES algorithm on the path planning under different obstacle scenarios is conducted by using the MATLAB platform. The results show that SAHBES can generate the shortest safe, smooth path in different complex water environments, considering the limitations of fundamental ship maneuvering operations compared to other algorithms, thus verifying the feasibility and efficiency of the proposed SAHBES algorithm.
Atmospheric near-surface stress and boundary layer wind responses to surface currents are examined with high resolution coupled atmosphere–ocean models over the Gulf Stream during winter. Because the ocean and atmosphere are linked through surface stress, the two fluids can cause dramatic changes through feedback processes. When the current feedback is included, we find that the current gradient in the cross-wind direction drives the stress curl pattern and wind curl pattern to have minima and maxima at locations matching those of the ocean surface vorticity pattern. Furthermore, we find the large- (>30 km) and small-scale, or submesoscale (<30 km), stress curl and wind curl responses to ocean surface vorticity are complimentary; however, the large- and small-scale wind divergence responses are counteractive. These responses (commonly called coupling coefficients) are found to depend on the relative position to the Gulf Stream maximum current. Throughout the atmospheric boundary layer, we find including the current feedback also leads to changes in the atmospheric secondary circulation on either side of the Gulf Stream extension. The winter seasonal means suggest the current feedback will impact climate, and investigating individual events, such as an atmospheric front passing over the Gulf Stream, suggests the current feedback will also impact the intensity of weather.
In this paper, the supercavitation of the parallel and tandem projectiles moving underwater with high-speed under the condition with/without lateral flows is numerically simulated by the volume of fraction (VOF) model. The motion of the projectiles was handled by the overlapping grid and six degrees of freedom (DOF) techniques. The supercavitation evolution and the hydrodynamic characteristics of the projectiles were analyzed for the parallel and tandem projectiles under different conditions. The results show that the cavity shape is symmetrical under the condition without lateral flows, but is no longer symmetrical under the conditions with lateral flows. The asymmetry of the cavity contour increases with the velocity of the lateral flow. For the parallel projectiles, the change trends of the axial velocity of projectile 1 and projectile 2 are nearly the same. The offset velocity of projectile 1 and projectile 2 increases with the increase in the velocity of the lateral flow. The deflection angle of projectile 1 decreases with the increase in the lateral flow velocity but that of projectile 2 increases with the increase in the lateral flow velocity. At <i>t</i> = 3.0 ms, the deflection angle of projectile 2 is up to 20° under the condition of the lateral flow velocity of 11.25%, while the deflection angle of projectile 1 and 2 under other conditions is in the range of 5°. For the tandem projectiles, the axial velocity of projectile 1 gradually decreases. The change trend of the axial velocity of projectile 2 at first is the same as that of projectile 1, and then the change is dependent on the velocity of the lateral flow. Under the condition of the lateral flow velocity with 11.25%<i>V<sub>p</sub></i>, projectile 2 cannot enter the cavity of the front projectile. The change trend of the axial velocity of projectile 2 is similar as but somewhat slower than that of projectile 1. For the parallel projectiles, the ballistic stability of the projectile on the oncoming side is better than that of the projectile on the backflow side. Whether parallel or tandem projectiles, the ballistic stability of projectile 2 becomes worse with the increase in the lateral flow velocity.
Edoardo Gramigna, Riccardo Lasagni Manghi, Marco Zannoni
et al.
Hera represents the European Space Agency's inaugural planetary defense space mission and plays a pivotal role in the Asteroid Impact and Deflection Assessment international collaboration with NASA DART mission that performed the first asteroid deflection experiment using the kinetic impactor techniques. With the primary objective of conducting a detailed post-impact survey of the Didymos binary asteroid following the DART impact on its small moon called Dimorphos, Hera aims to comprehensively assess and characterize the feasibility of the kinetic impactor technique in asteroid deflection while conducting an in-depth investigation of the asteroid binary, including its physical and compositional properties as well as the effect of the impact on the surface and shape of Dimorphos. In this work, we describe the Hera radio science experiment, which will allow us to precisely estimate critical parameters, including the mass, which is required to determine the momentum enhancement resulting from the DART impact, mass distribution, rotational states, relative orbits, and dynamics of the asteroids Didymos and Dimorphos. Through a multi-arc covariance analysis, we present the achievable accuracy for these parameters, which consider the full expected asteroid phase and are based on ground radiometric, Hera optical images, and Hera to CubeSats InterSatellite Link radiometric measurements. The expected formal uncertainties for Didymos and Dimorphos GM are better than 0.01% and 0.1%, respectively, while their J2 formal uncertainties are better than 0.1% and 10%, respectively. [...]
Andrea Márquez Escamilla, Paloma Herrera-Racionero, José Pastor Gimeno
et al.
The fishing sector is facing major economic and environmental challenges worldwide. However, at least in developed countries, it is also undergoing a major social crisis. This research has tried to quantify and validate this subjective feeling of deep crisis, based on objective and quantitative data referring to the Spanish Mediterranean. Indeed, the results show alarming data. Different scattered databases have been analyzed and it has been exposed that in only 15 years the number of vessels, power and tonnage has decreased by about 40%; as for fishermen, their number has decreased by about 30%, also revealing a serious problem of generational replacement, since in only 10 years, the average age of fishermen has increased by 3 years. A simple linear regression model shows that this downward trend in the number of boats and fishermen will continue at least in the short term. The data obtained invite a deep reflection on the future or even the very survival of fishing in the Spanish Mediterranean in the medium term. This reflection is not limited to this specific area but can be extrapolated to many other fishing areas.