Benchmark study on motions and loads of a 6750-TEU containership

AbstractThis study deals with a benchmark test on the performance of seakeeping analysis codes, which was carried out as part of the 2nd ITTC–ISSC joint workshop in 2014. Eleven institutes participated in the benchmark test with seventeen analysis codes. The target ship was the 6750-TEU containership, and the test of its flexible scale model was conducted by KRISO. A test matrix was composed of one condition for linear responses and three conditions for nonlinear responses. Participants were requested to conduct computational simulations and submit their heave, pitch, and vertical bending moment results in head regular waves. The computational results obtained are compared with each other using statistical analysis. The comparison reveals the performances and trends of the computational results. In addition, all the model data is included in the paper in order to encourage readers to participate in the benchmark test

Computation of higher-order hydrodynamic forces on ships and offshore structures in waves

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1999.Includes bibliographical references (leaves 163-170).by Yonghwan Kim.Ph.D

Effect of current step-down on the growth and hardness of PEO coatings on Al6061 alloy

AbstractIn this study, plasma electrolytic oxidation (PEO) treatments were conducted on Al6061 plates using silicate containing alkaline electrolyte. The hardness variation with the growth of the PEO coating was investigated under two different regimes of applied AC current. The first was a continuous supply with a constant current density of 500mA/cm2 for 60 or 90min. The other was a current supply of 500mA/cm2 for 60min followed by a current step-down to 200mA/cm2 and continuous treatment for 30min. In the case of a constant current for 60min, the coating thickness and Vickers hardness increased to 150μm and 1300 Hv, respectively. With further processing in the same manner, the coating grew thicker while its hardness gradually decreased to 900 Hv. In the case of a current step-down, no significant thickness increase was observed, but there was a hardness increase up to 1800 Hv. Analysis of the PEO coatings by SEM/EDS and XRD revealed that all their function layers were comprised mainly of α-Al2O3 with hardness dependent on density. The current step-down method contributes to the densification of the function layer in a PEO coating, and thus increases the hardness

Self-Stabilizing Construction of a Minimal Weakly ST\mathcal{ST}-Reachable Directed Acyclic Graph

We propose a self-stabilizing algorithm to construct a minimal weakly $\mathcal{ST}$-reachable directed acyclic graph (DAG), which is suited for routing messages on wireless networks. Given an arbitrary, simple, connected, and undirected graph $G=(V, E)$ and two sets of nodes, senders $\mathcal{S} (\subset V)$ and targets $\mathcal{T} (\subset V)$, a directed subgraph $\vec{G}$ of $G$ is a weakly $\mathcal{ST}$-reachable DAG on $G$, if $\vec{G}$ is a DAG and every sender can reach at least one target, and every target is reachable from at least one sender in $\vec{G}$. We say that a weakly $\mathcal{ST}$-reachable DAG $\vec{G}$ on $G$ is minimal if any proper subgraph of $\vec{G}$ is no longer a weakly $\mathcal{ST}$-reachable DAG. This DAG is a relaxed version of the original (or strongly) $\mathcal{ST}$-reachable DAG, where every target is reachable from every sender. This is because a strongly $\mathcal{ST}$-reachable DAG $G$ does not always exist; some graph has no strongly $\mathcal{ST}$-reachable DAG even in the case $|\mathcal{S}|=|\mathcal{T}|=2$. On the other hand, the proposed algorithm always constructs a weakly $\mathcal{ST}$-reachable DAG for any $|\mathcal{S}|$ and $|\mathcal{T}|$. Furthermore, the proposed algorithm is self-stabilizing; even if the constructed DAG deviates from the reachability requirement by a breakdown or exhausting the battery of a node having an arc in the DAG, this algorithm automatically reconstructs the DAG to satisfy the requirement again. The convergence time of the algorithm is $O(D)$ asynchronous rounds, where $D$ is the diameter of a given graph. We conduct small simulations to evaluate the performance of the proposed algorithm. The simulation result indicates that its execution time decreases when the number of sender nodes or target nodes is large

Comparison of proprioception, strength, and dynamic balance between aquatic and cycling trainings after arthroscopic partial meniscectomy during early rehabilitation in young male athletes

Arthroscopic partial meniscectomy (APM) strives to preserve knee biomechanics and function after the meniscal rupture. However, patients undergoing APM experience long-term impacts like proprioceptive deficit and functional decline. This study aimed to examine and compare the effects of aquatic and leg cycling trainings on young athletes undergone APM. Ninety-seven male athletes with APM were assigned to aquatic training group (ATG, n = 49) and cycling training group (CTG, n = 48). Both intervention trainings were conducted three times a week for 6 weeks after 2 weeks of APM. The rehabilitation training was the same in each session. The International Knee Documentation Committee (IKDC) questionnaire scores, knee joint position sense, Y-balance test, and isokinetic knee strength were measured before and after the interventions. Significant improvements were observed after the trainings regarding measured variables for both ATG and CTG groups. Comparison of the two groups found that ATG group had higher scores in IKDC and Y-balance test, greater muscle power, and lower absolute error in the joint position sense test compared to the CTG group. ATG and CTG are thus considered effective training interventions in early rehabilitation phase following the APM. Moreover, ATG may be more conducive than CTG in improving subjective knee symptoms, proprioception, and muscle power

Investigating Poor Performance Regions of Black Boxes: LIME-based Exploration in Sepsis Detection

Interpreting machine learning models remains a challenge, hindering their adoption in clinical settings. This paper proposes leveraging Local Interpretable Model-Agnostic Explanations (LIME) to provide interpretable descriptions of black box classification models in high-stakes sepsis detection. By analyzing misclassified instances, significant features contributing to suboptimal performance are identified. The analysis reveals regions where the classifier performs poorly, allowing the calculation of error rates within these regions. This knowledge is crucial for cautious decision-making in sepsis detection and other critical applications. The proposed approach is demonstrated using the eICU dataset, effectively identifying and visualizing regions where the classifier underperforms. By enhancing interpretability, our method promotes the adoption of machine learning models in clinical practice, empowering informed decision-making and mitigating risks in critical scenarios.Comment: Accepted at the 1st World Conference on eXplainable Artificial Intelligence - Late-breaking work, Demos and Doctoral Consortium, 202

Effect of high-intensity sports specific training and high-intensity interval training on sprained ankle male adolescent soccer athletes before return-to-play

Ankle sprain is a highly observed injury in soccer due to repeated strenuous movements. Rehabilitation after injury leads to decreased physical strength and muscle-joint function. The ankle sprained patients need improved soccer specific fitness and ankle function simultaneously. Therefore, current study aimed to compare high-intensity sports specific training (HISST) with high-intensity interval training (HIIT) to identify effective training for fitness and lower-extremity functions. A total of 56 high school male soccer players (HIIT: 28, HISST: 28) who survived the acute phase due to ankle sprain participated the study. In the intervention period of 4 weeks, the HISST and HIIT groups were randomly assigned. Physical fitness and lower-extremity function tests were performed before and after the intervention. Physical fitness measurements included Volume Oxygen peak (VO2peak), anaerobic power, isokinetic ankle eversion strength, while lower extremity function tests consisted of Y-balance and hop tests. In both groups, VO2peak, exercise time, peak power, and eversion strength improved after the intervention, with significant improvement in all Y-balance subtests and hop tests (p < 0.05). Regarding the posteromedial and posterolateral directions of the Y-balance test, and the crossover of the hop tests, HISST was significantly higher (p < 0.05) than HIIT in the post-intervention test. Concludingly, HIIT and HISST can simultaneously improve VO<, abductor strength, and lower extremity function in sprained ankle athletes before returning to competition. Additionally, HISST was slightly more effective than HIIT for mediolateral balance and crossover hopping