Hasil untuk "Naval Science"

Swaminathan Nithya, Arularasi Veerabadrasamy, Gunasekaran Kandaswamy et al.

Wei Li, Ya Guo, Shuzhao Li et al.

The randomness and complexity of ice loads present major challenges to the safety and stability of offshore platforms. Traditional methods for identifying ice loads often lack accuracy and adaptability under changing environmental conditions. This study proposes a novel inversion method based on Temporal Convolutional Networks (TCNs), integrating finite element simulation with deep learning to effectively identify random ice loads. A random ice load model is first developed, and its dynamic characteristics are validated through finite element analysis. The TCN model is then applied to capture the time-dependent features of ice loads. To improve the model’s generalization ability, its hyperparameters are optimized using particle swarm optimization (PSO). The results show that the TCN model achieves goodness-of-fit (R²) values of 0.821 and 0.808 on the training and test sets, respectively, indicating strong predictive performance. Under different ice thickness and velocity conditions, the model achieves R² values close to 0.99, demonstrating high robustness. This work represents the first application of TCN to ice load identification. By combining it with simulation data, we offer a high-precision, data-driven approach for dynamic load identification, enhancing the efficiency and reliability of safety assessments for conical offshore platforms.

Lin Liu, Jie Lv, Xiuxiu Wang et al.

CHEN Shi, YANG Linsen, LIU Yihong, LUO Huan, ZANG Tianlei, ZHOU Buxiang

Newly built microgrids lack historical operation data, making it challenging to predict renewable power output accurately using conventional data-driven methods, which in turn affects the accuracy of scheduling plans. To address this problem, an optimal scheduling method for newly built microgrids in scenarios with limited sample data is proposed. First, an improved network structure integrating a domain adversarial neural network with a long-short-term memory network is designed. The domain adversarial approach and gradient inversion mechanism are incorporated into transfer learning to improve the generalization ability of the model. This reduces the domain distribution discrepancy in the data, and uses the rich operation data of power stations with similar output characteristics to predict the output of the target station, which overcomes the challenge of poor accuracy under the conditions of small samples. Additionally, the optimal scheduling model is transformed into a Markov decision process and solved using double-delay deep deterministic policy gradient algorithm. Finally, the effectiveness of the proposed method is validated through a case study involving an improved CIGRE 14-node microgrid.

Bu X, Feng L, Guo J et al.

Xiaolin Bu,1,* Liwei Feng,2,* Jing Guo,3 Rongzhu Yu,2 Xinling Bi4 1Laboratory of Laser and Medical Innovation Application, Department of Dermatology, Gongli Hospital of Shanghai Pudong New Area, Shanghai, People’s Republic of China; 2School of Gongli Hospital Medical Technology, University of Shanghai for Science and Technology, Shanghai, People’s Republic of China; 3Postgraduate Training Base at Shanghai Gongli Hospital, Ningxia Medical University, Shanghai, People’s Republic of China; 4Department of Dermatology, Changhai Hospital, Naval Medical University, Shanghai, People’s Republic of China*These authors contributed equally to this workCorrespondence: Xinling Bi, Department of Dermatology, Changhai Hospital, Naval Medical University, 168 Changhai Road, YangPu District, Shanghai, People’s Republic of China, Email bixinling@163.comAbstract: A 65-year-old Asian male presented with a circular skin lesion on the flexor aspect of the right calf that first appeared at age 13 and gradually expanded peripherally. Six months prior to presentation, a dark brown, horn-like keratotic lesion with a hard texture emerged on the annular lesion, growing progressively without pain or pruritus. The cutaneous horn was surgically excised, and the annular lesion underwent biopsy. Pathological findings revealed abundant mucin in dermal collagen, dense histiocyte infiltration, and focal mild collagen degeneration, confirming a diagnosis of granuloma annulare complicated by a cutaneous horn.Keywords: cutaneous horn, granuloma annulare, keratotic

Rahid Zaman, Md Navid Imtiaz Rifat, Fairuz Maliha et al.

Liang Sun, Yang Li, Jiujiang Yan et al.

In recent years, academic research on perovskite solar cells (PSCs) has attracted remarkable attention, and one of the most crucial issues is promoting the power conversion efficiency (PCE) and operational stability of PSCs. Generally, modification of the electron or hole transport layers between the perovskite layers and electrodes via surface engineering is considered an effective strategy because the inherent structural defects between charge carrier transport layers and perovskite layers can be reshaped and modified by adopting the functional nanomaterials, and thus the charge recombination rate can be naturally decreased. At present, large amounts of available nanomaterials for surface modification of the perovskite films are extensively investigated, mainly including nanocrystals, nanorods, nanoarrays, and even colloidal quantum dots (QDs). In particular, as unique size-dependent nanomaterials, the diverse quantum properties of colloidal QDs are different from other nanomaterials, such as their quantum confinement effects, quantum-tunable effects, and quantum surface effects, which display great potential in promoting the PCE and operational stability of PSCs as the charge carriers in perovskite layers can be effectively tuned by these quantum effects. However, preparing QDs with a neat and desirable size remains a technical difficulty, even though the present chemical engineering is highly advanced. Fortunately, the rapid advances in laser technology have provided new insight into the precise preparation of QDs. In this review, we introduce a new approach for preparing the QDs, namely pulsed laser irradiation in colloids (PLIC), and briefly highlight the innovative works on PLIC-prepared QDs for the optimization of PSCs. This review not only highlights the advantages of PLIC for QD preparation but also critically points out the challenges and prospects of QD-based PSCs.

A. Hayrapetyan, A. Tumasyan, W. Adam et al.

A search is presented for new Higgs bosons in proton-proton (pp) collision events in which a same-sign top quark pair is produced in association with a jet, via the pp→tH/A→ttc‾ and pp→tH/A→ttu‾ processes. Here, H and A represent the extra scalar and pseudoscalar boson, respectively, of the second Higgs doublet in the generalized two-Higgs-doublet model (g2HDM). The search is based on pp collision data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 138fb−1. Final states with a same-sign lepton pair in association with jets and missing transverse momentum are considered. New Higgs bosons in the 200–1000 GeV mass range and new Yukawa couplings between 0.1 and 1.0 are targeted in the search, for scenarios in which either H or A appear alone, or in which they coexist and interfere. No significant excess above the standard model prediction is observed. Exclusion limits are derived in the context of the g2HDM.

Shijian ZHOU, Pengli ZHU, Siyuan LIU et al.

The unsupervised enhancement technology for underwater images is mainly oriented towards specific distortion factors and exhibits limited adaptability towards various underwater distorted images. The content attribute(structure) of the image will migrate and change with the style attribute(appearance), resulting in an uncontrolled enhancement effect and affecting the stability and accuracy of subsequent environmental perception and processing. To address this issue, an unsupervised controllable enhancement method of underwater images based on multi-domain attribute representation disentanglement(MARD) was proposed in the paper. First, a framework of multi-domain unified representation disentanglement cycle-consistent adversarial translations was designed, thereby enhancing the algorithm’s adaptability to multiple distortion factors. Subsequently, a dual-encoding and conditional decoding network structure was constructed. Finally, a series of losses for MARD was designed to enhance the independence and controllability of quality, content, style, and other attribute representations. Experimental results demonstrate that the proposed algorithm not only eliminates various distortions such as color aberration, blur, noise, and low illumination in underwater images but also quantify the image style codes by linear interpolation for controllable enhancement of underwater images.

Ying Wu, Yan Ling, Bao-Dong Qin et al.

The sustained benefit of immunotherapy-based regimens in epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) after EGFR-tyrosine kinase inhibitor (TKI) failure is debatable. Neither Checkmate-722 nor Keynote-789 reached the prespecified statistical level of clinical benefit, but the ORIENT-31 and ATTLAS trials showed that the addition of a VEGF inhibitor to immunotherapy plus chemotherapy could significantly prolong survival. However, head-to-head comparisons of the efficacy of immunotherapy plus bevacizumab with chemotherapy versus that of immunotherapy with chemotherapy in this patient population are lacking. In addition, the critical question of who would benefit from an immunotherapy-based regimen remains unclear. We conducted an indirect comparative meta-analysis using chemotherapy as a common comparator to classify the relative efficacy of the two immunotherapy-based regimens. The indirect comparison showed that immunotherapy and bevacizumab plus chemotherapy had a significantly better progression-free survival (PFS) (HRIO+Bev+Chemo/IO+Chemo=0.71, 95% CI 0.55 to 0.91) than immunotherapy plus chemotherapy. The EGFR mutation type and T790M mutation were found to be significantly associated with PFS of immunotherapy-based regimens. Compared with their counterparts, patients with L858R (HR 0.52, 95%CI 0.37 to 0.72), without T790M mutation (HR 0.50, 95% CI 0.35 to 0.71) tended to benefit significantly more from immunotherapy-based regimens. In conclusion, our findings support that the addition of VEGF inhibitor to immunotherapy and chemotherapy could be the preferred option for TKI-resistant, EGFR-mutated NSCLC, and that L858R mutation and T790M negativity could be identified as efficacy-associated factors for immunotherapy-based regimens.

Samuel Brenner, Jim Thomson, Luc Rainville et al.

Abstract Observations of sea ice and the upper ocean from three moorings in the Beaufort Sea quantify atmosphere–ice–ocean momentum transfer, with a particular focus on the inertial-frequency response. Seasonal variations in the strength of mixed layer (ML) inertial oscillations suggest that sea ice damps momentum transfer from the wind to the ocean, such that the oscillation strength is minimal under sea ice cover. In contrast, the net Ekman transport is unimpacted by the presence of sea ice. The mooring measurements are interpreted with a simplified one-dimensional ice–ocean coupled “slab” model. The model results provide insight into the drivers of the inertial seasonality: namely, that a combination of both sea ice internal stress and ocean ML depth contribute to the seasonal variability of inertial surface currents and inertial sea ice drift, while under-ice roughness does not. Furthermore, the importance of internal stress in damping inertial oscillations is different at each mooring, with a minimal influence at the southernmost mooring (within the seasonal ice zone) and more influence at the northernmost mooring. As the Arctic shifts to a more seasonal sea ice regime, changes in sea ice cover and sea ice internal strength may impact inertial-band ice–ocean coupling and allow for an increase in wind forcing to the ocean.

Kanghao Wang, Xiqiu Han, Yejian Wang et al.

Understanding the dynamics of deep-sea hydrothermal plumes and the depositional pattern of hydrothermal particles is essential for tracking the submarine hydrothermal venting site, prospecting polymetallic sulfide resources, as well as deciphering biogeochemistry cycling of marine elements. In this paper, a numerical model of the deep-sea hydrothermal plume is established based on the topography and long-term current monitoring data of the Wocan-1 hydrothermal field (WHF-1), Carlsberg Ridge, Northwest Indian Ocean. The model allows for a reconstruction of the hydrothermal plume in terms of its structure, velocity field, and temperature field. The relationships between the maximum height of the rising plume and the background current velocity, and between the height of the neutral-buoyancy layer and the background current velocity are established, respectively. The transport patterns of the hydrothermal particles and their controlling factors are revealed. Using hydrothermal particles with a density of ~5000 kg/m³ (i.e., pyrite grains) as an example, it is found that pyrite larger than 1 mm can only be found near the venting site. Those in the size 0.3–0.5 mm can only be found within 137–240 m from the venting site, while those smaller than 0.2 mm can be transported over long distances of more than 1 km. Using the vertical temperature profiling data of WHF-1 obtained during the Jiaolong submersible diving cruise in March 2017, we reconstruct the past current velocity of 10 cm/s, similar to the current data retrieved from the observational mooring system. Our model and the findings contribute to a better understanding of the hydrothermal system of WHF-1, and provide useful information for tracing the hydrothermal vents, prospecting the submarine polymetallic sulfide resources, designing the long-term observation networks, and relevant studies on element cycling and energy budget.

T GS Basappa Varun, Angshuman Dutta, Rahul Naga et al.

Inroduction: Nasal obstruction is the most common complaint in an average ENT practice, and a deviated nasal septum is the most common cause of nasal obstruction. The deformities of the septum are usually congenital, developmental, traumatic, or iatrogenic in nature with traumatic and iatrogenic being the most common. The aim of the study was to evaluate patient-based outcomes on subjective-based opinion in patients undergoing endoscopic septoplasty. Methods: This study was conducted in a tertiary care hospital setting in western Maharashtra. This was a prospective observational study.The present study was conducted on 50 patients who presented with signs and symptoms attributed to septal deviation who underwent endoscopic septoplasty and followed up in the department of otorhinolaryngology, head and neck surgery, tertiary care hospital, Mumbai, Maharashtra.The results of our study were analyzed on SPSS Software using “Paired t-test”. Results: On the statistical analysis of the Nasal Obstruction Symptom Evaluation score of patients (n = 50) at baseline and at postoperative 3- and 6-month follow-up, mean + standard deviation was 61.2 ± 11.18, 9.1 ± 5.32, and 8.1 ± 4.51, respectively, with P < 0.0001 preoperative and 3-month postoperative follow-up which is highly significant and P > 0.05 for 3- and 6-month follow-up and hence insignificant. Conclusion: Endoscopic septoplasty results in significant improvement in disease-specific quality of life with high patient satisfaction.

Luciana das Neves, Carolina Andrade, Maria Francisca Sarmento et al.

Earth observation can provide managers with valuable information on ongoing coastal processes and major trends in coastline evolution, especially in data-poor regions. This paper examines the use of optical satellite images in the mapping of the changes in shoreline position before, during, and after the implementation of a protection scheme. The aim of this paper is twofold: (i) to demonstrate the potential of satellite imagery as an effective, robust, and low-cost tool to remotely monitor the effectiveness of protective structures based on a large-scale case study in West Africa; and (ii) to compile lessons learned from this case study that can be used in the design of future interventions. The analysis shows that before the implementation of the protection scheme, the coastal sector was retreating at a rate of −1.6 m/year, which is in line with the average retreat rates reported in other studies for the region. After project implementation, this trend reversed into shoreline accretion at a rate of +1.0 m/year, locally experiencing positive and negative oscillations in the short term. Furthermore, the shoreline-extracted positions proved useful in assessing the impact of differences in the groynes’ permeability with respect to temporary leeside erosion. Finally, it is recommended to continue this monitoring to assess long-term trends.

Sungjin Cho, Qiuyang Tao, Paul Varnell et al.

Ning Zhou, Lawrence Lau, Ruibin Bai et al.

Ultrawideband (UWB) technology has received considerable attention in indoor positioning because of its high ranging accuracy. However, UWB range measurements can be contaminated by the delayed signals resulting from obstruction and reflection in difficult indoor environments. These signals introduce delays to range measurements and degrade positioning accuracy if they are not resolved properly. In order to mitigate the effects of delayed range measurements on positioning and achieve a high-accuracy position estimation, this paper proposes a robust particle-filter-based indoor positioning algorithm. In the proposed algorithm, an outlier detection method is proposed for delayed measurement identification, and a constrained particle sampling method is proposed to optimize the distribution of the predicted particles. The proposed algorithm is assessed rigorously through testing. The test results show that the proposed algorithm can effectively identify delayed range measurements, mitigate their effects on position estimation, and improve positioning accuracy.

McArthur Jones, John T. Emmert, Quan Gan et al.

Currently, thermospheric species densities and temperatures between ∼100 and 200 km are not known to the accuracy needed to fully characterize how the thermosphere transitions from a well-mixed atmosphere to a diffusively separated atmosphere with zero temperature gradient. This greatly inhibits scientific discovery attainable from either models or observations in this region, especially the understanding of mechanisms that drive thermosphere and ionospheric variability from space weather to climatological time scales. The purpose of this paper is to highlight the importance and critical need for new, global, height-resolved neutral composition (O, O2, N2) and temperature measurements in the new ignorosphere: the 100–200 km region of the thermosphere. We conclude with observation recommendations and requirements for new comprehensive composition and temperature measurements in the 100–200 km altitude region that would lead to significant advances in thermosphere-ionosphere science, space weather, and space climate.

Almudena Filgueira-Vizoso, Laura Castro-Santos, David Cordal Iglesias et al.

This paper defines a methodology for the economic feasibility analysis of a floating offshore wind farm composed of tensioned leg platforms, which are part of the EU ARCWIND research project. In this context, the phases and subphases of its life-cycle process are considered to deal with aspects such as bathymetry, characteristics of the platforms, distance from the farm to shore, distance from the farm to port and offshore wind speed. All the costs and other external parameters such as capital cost, electric tariff, interest rate, percentage of financing and corporate tax have been analysed to calculate the internal rate of return, net present value, discounted pay-back period and levelized cost of energy of the farm. This work studies a farm composed of TLP offshore wind platforms designed by CENTEC and located at Ribadeo in Spain. Results indicate the costs and the economic feasibility of this platform for deep waters. They indicate that the platform is economically feasible for the location selected.

Abdelrhman Mohamed, Phuc T. Ha, Haluk Beyenal

Xuan Ni, Leiping Xue

Scour prediction is essential for the design of offshore foundations. Several methods have been proposed to predict the equilibrium scour depth for monopiles. By introducing an effective diameter, such methods could also be applied to predicting scour depth for pile groups. Yet, there are still difficulties in estimating the equilibrium scour depth of foundations in complex shapes, such as the tripod foundation. This study investigates the clear-water scour around the tripod and hexapod foundations through laboratory experiments, with uniform bed sediment and steady current. Here, the authors propose an approach to calculate the effective diameter for the tripod and hexapod models, which is similarly as for the pile groups. Three widely-used methods in predicting equilibrium scour depth have been evaluated, and the best method is recommended.