AbstractProgrammable photonic integrated circuits (PICs) consisting of reconfigurable on-chip optical components have been creating new paradigms in various applications, such as integrated spectroscopy, multi-purpose microwave photonics, and optical information processing. Among many reconfiguration mechanisms, non-volatile chalcogenide phase-change materials (PCMs) exhibit a promising approach to the future very-large-scale programmable PICs, thanks to their zero static power and large optical index modulation, leading to extremely low energy consumption and ultra-compact footprints. However, the scalability of the current PCM-based programmable PICs is still limited since they are not directly off-the-shelf in commercial photonic foundries now. Here, we demonstrate a scalable platform harnessing the mature and reliable 300 mm silicon photonic fab, assisted by an in-house wide-bandgap PCM (Sb2S3) integration process. We show various non-volatile programmable devices, including micro-ring resonators, Mach-Zehnder interferometers and asymmetric directional couplers, with low loss (~0.0044 dB/µm), large phase shift (~0.012 π/µm) and high endurance (>5000 switching events with little performance degradation). Moreover, we showcase this platform’s capability of handling relatively complex structures such as multiple PIN diode heaters in devices, each independently controlling an Sb2S3 segment. By reliably setting the Sb2S3 segments to fully amorphous or crystalline state, we achieved deterministic multilevel operation. An asymmetric directional coupler with two unequal-length Sb2S3 segments showed the capability of four-level switching, beyond cross-and-bar binary states. We further showed unbalanced Mach-Zehnder interferometers with equal-length and unequal-length Sb2S3 segments, exhibiting reversible switching and a maximum of 5 ($$N+1,N=4$$ N + 1 , N = 4 ) and 8 ($${2}^{N},N=3$$ 2 N , N = 3 ) equally spaced operation levels, respectively. This work lays the foundation for future programmable very-large-scale PICs with deterministic programmability.
With the increasing demand for marine resource development and environmental protection, underwater robots have an urgent need for flexible, safe, and efficient soft grasping technology. This paper described three main actuation design methods for underwater soft grippers: fluid variable pressure drive, cable drive, and smart material drive. Based on this, the research progress of key technologies such as bio-inspired design, stiffness adjustment technology, integration of grasping and perception, and multi-modal grasping was analyzed. Combined with typical application scenarios such as marine waste cleanup, aquatic product fishing, underwater archaeology, and cultural relic protection, as well as biological sample collection, the unique advantages of soft grippers in non-destructive sampling, adaptability to multiple types of objects, and fine operations in the deep sea were analyzed. Finally, the future research directions of underwater soft grippers were prospected, and it is pointed out that efforts should be focused on the research and development of high-performance underwater intelligent materials, the integration of multiple driving methods, and the optimization of energy and control systems, so as to promote the evolution of the gripper towards deep sea and intelligentization and achieve reliable underwater operations in all scenarios.
High Speed Marine Vessels (HSMV) have been used for passenger services in Norwegian coastal waters since the early 1960-ties (hydrofoil vessels Sleipner, Vingtor and Teisten). The need for fast transfer of passengers along the sparsely populated Norwegian coast made the Norwegian ship designers and smaller shipyards eager to design and build smaller HSMV, both for commercial and governmental (navy) customers. The joint governmental and industry funded High Speed Craft program (1994 – 1997) played an important part in the growth of the Norwegian HSMV industry. In 1999 a serious accident happened with one of the HSMV operating the Stavanger – Bergen route (grounding on a reef when the vessel was at full speed), causing the death of 16 people. The accident had a major impact on the HSMV development and utilization. In addition to passenger vessels, the industry has developed fast patrol boats, ambulance and Search and Rescue vessels. Some operability aspects and challenges for the existing fleet of HSMV will be presented.
This study investigates the impact of reducing waiting times for port berth on improving the Carbon Intensity Indicator (CII) ratings of Korean-flagged container ships. As the International Maritime Organization (IMO)’s CII regulation mandates corrective actions for poorly rated ships for Greenhouse Gas (GHG) reduction in international shipping, the analysis focuses on container ships with projected D or E ratings by 2035. Using Automatic Identification System (AIS) data from ships, this study identifies annual waiting times and simulates changes in CII ratings under scenarios of reduced waiting times (30%, 50%, 70%, and 100%). The relationship between ship speed and fuel consumption was established by analyzing the recent literature, and the CII improvement was evaluated based on IMO Data Collection System (DCS) 2022 data. The results show that a 30% reduction in waiting time can lower CO<sub>2</sub> emissions by 12.18% and improve the CII rating by one or two levels for approximately half of the sample ships. However, a 50% reduction or more is required to maintain improved ratings beyond 2030. The findings highlight the significance of just-in-time (JIT) practices in minimizing latency and enhancing regulatory compliance. The policy recommendations advocate for prioritizing port call optimization and recommend the adoption of JIT as a measure to achieve the IMO’s GHG reduction targets.
The fundus manifestations of pseudopapilledema closely resemble those of optic disc edema, making their differentiation particularly challenging in certain clinical situations. However, rapid and accurate diagnosis is crucial for alleviating patient anxiety and guiding treatment strategies. This study proposes an efficient low-complexity hybrid model, WHA-Net, which innovatively integrates three core modules to achieve precise auxiliary diagnosis of pseudopapilledema. First, the wavelet convolution (WTC) block is introduced to enhance the model’s characterization capability for vessel and optic disc edge details in fundus images through 2D wavelet transform and deep convolution. Additionally, the hybrid attention inverted residual (HAIR) block is incorporated to extract critical features such as vascular morphology, hemorrhages, and exudates. Finally, the Agent-MViT module effectively captures the continuity features of optic disc contours and retinal vessels in fundus images while reducing the computational complexity of traditional Transformers. The model was trained and evaluated on a dataset of 1793 rigorously curated fundus images, comprising 895 normal optic discs, 485 optic disc edema (ODE), and 413 pseudopapilledema (PPE) cases. On the test set, the model achieved outstanding performance, with 97.79% accuracy, 95.55% precision, 95.69% recall, and 98.53% specificity. Comparative experiments confirm the superiority of WHA-Net in classification tasks, while ablation studies validate the effectiveness and rationality of each module’s combined design. This research provides a clinically valuable solution for the automated differential diagnosis of pseudopapilledema, with both computational efficiency and diagnostic reliability.
Understanding the broad impact of science and science funding is critical to ensuring that science investments and policies align with societal needs. Existing research links science funding to the output of scientific publications but largely leaves out the downstream uses of science and the myriad ways in which investing in science may impact human society. As funders seek to allocate scarce funding resources across a complex research landscape, there is an urgent need for informative and transparent tools that allow for comprehensive assessments and visualization of the impact of funding. Here we present Funding the Frontier (FtF), a visual analysis system for researchers, funders, policymakers, university leaders, and the broad public to analyze multidimensional impacts of funding and make informed decisions regarding research investments and opportunities. The system is built on a massive data collection that connects 7M research grants to 140M scientific publications, 160M patents, 10.9M policy documents, 800K clinical trials, and 5.8M newsfeeds, with 1.8B citation linkages among these entities, systematically linking science funding to its downstream impacts. As such, Funding the Frontier is distinguished by its multifaceted impact analysis framework. The system incorporates diverse impact metrics and predictive models that forecast future investment opportunities into an array of coordinated views, allowing for easy exploration of funding and its outcomes. We evaluate the effectiveness and usability of the system using case studies and expert interviews. Feedback suggests that our system not only fulfills the primary analysis needs of its target users, but the rich datasets of the complex science ecosystem and the proposed analysis framework also open new avenues for both visualization and the science of science research.
Vishwanath Saragadam, Zheyi Han, Vivek Boominathan
et al.
Foveated imaging provides a better tradeoff between situational awareness (field of view) and resolution, and is critical in long wavelength infrared regimes because of the size, weight, power, and cost of thermal sensors. We demonstrate computational foveated imaging by exploiting the ability of a meta-optical frontend to discriminate between different polarization states and a computational backend to reconstruct the captured image/video. The frontend is a three-element optic: the first element, which we call the “foveal” element, is a metalens that focuses s-polarized light at a distance of f1 without affecting the p-polarized light; the second element, which we call the “perifovea” element, is another metalens that focuses p-polarized light at a distance of f2 without affecting the s-polarized light. The third element is a freely rotating polarizer that dynamically changes the mixing ratios between the two polarization states. Both the foveal element (focal length=150mm; diameter=75mm) and the perifoveal element (focal length=25mm; diameter=25mm) were fabricated as polarization-sensitive, all-silicon, meta surfaces resulting in a large-aperture, 1:6 foveal expansion, thermal imaging capability. A computational backend then utilizes a deep image prior to separate the resultant multiplexed image or video into a foveated image consisting of a high resolution center and a lower-resolution large field of view context. We build a prototype system and demonstrate 12 frames per second real-time, thermal, foveated image and video capture..
Floating photovoltaics (PVs) are progressively constructed in the ocean sea; therefore, the effect that freak waves have on their structural design needs to be considered. This paper developed a dedicated numerical model coupling the floating PV platform and mooring line structures to investigate their dynamic responses under freak waves. A feasible superposition approach is presented to generate freak wave sequences via the combination of transient waves and random waves. A large floating PV platform moored by twenty lines for a water depth of 45 m was designed in detail according to the actually measured ocean environmental and geological conditions. The global time domain analyses of the floating PV mooring structures were implemented to obtain dynamic responses, including PV platform motions and the mooring line configuration and tension under freak waves. A comparison of the response results with those caused by random waves was conducted to illustrate the intuitive evidence of the freak wave effects, which offer a significant reference for the preliminary design of the floating PV platform and mooring line structures.
This study examines the in-situ lateral static load behavior of a closed-diaphragm wall foundation, aiming to better understand its load–displacement response, structural behavior, and soil interaction under horizontal loading. An in-situ static load test was conducted with a maximum applied load of 70 MN, revealing that the diaphragm wall initially exhibits a linear load–displacement response, which becomes increasingly nonlinear as the load increases. The horizontal displacement of the lateral walls is nearly identical to the overall displacement of the diaphragm wall, making it a reliable indicator of the wall’s load state, particularly when it is challenging to measure total displacement. The wall behaves as a rigid body with minimal relative displacement between sections, and overturning failure is identified as the primary failure mode. Earth pressure distribution varies around the wall: passive earth pressure is observed at the front edge, while active and passive pressures alternate at the rear edge. These findings provide valuable insights into the design of diaphragm wall foundations, emphasizing the importance of lateral displacements.
Due to the poor bias repeatability and large random noise of a micro electro mechanical system (MEMS), the Allan variance was used to analyze the random angle walk of MEMS. The information fusion algorithm of array gyro was designed by using Allan variance identification value and weighted least square method, which could effectively reduce the random angle walk and respond to the true angular rate in real time under both static and dynamic conditions. For the constant drift of MEMS gyro, a two-position calibration scheme was designed combined with the observability of the error of the inertial navigation system, so as to complete system-level calibration of constant drift. Simulation results show that the method proposed in this paper effectively reduces the random angle walk and the constant drift of MEMS gyro and significantly improves the inertial measurement accuracy of MEMS.
The CMS collaboration, A. Tumasyan, W. Adam
et al.
Abstract The hydrodynamic flow-like behavior of charged hadrons in high-energy lead-lead collisions is studied through multiparticle correlations. The elliptic anisotropy values based on different orders of multiparticle cumulants, v 2{2k}, are measured up to the tenth order (k = 5) as functions of the collision centrality at a nucleon-nucleon center-of-mass energy of s NN $$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV. The data were recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 0.607 nb −1. A hierarchy is observed between the coefficients, with v 2{2} > v 2{4} ≳ v 2{6} ≳ v 2{8} ≳ v 2{10}. Based on these results, centrality-dependent moments for the fluctuation-driven event-by-event v 2 distribution are determined, including the skewness, kurtosis and, for the first time, superskewness. Assuming a hydrodynamic expansion of the produced medium, these moments directly probe the initial-state geometry in high-energy nucleus-nucleus collisions.
Nuclear and particle physics. Atomic energy. Radioactivity
Philippe Gris, Humna Awan, Matthew R. Becker
et al.
The Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will image billions of astronomical objects in the wide-fast-deep primary survey and in a set of minisurveys including intensive observations of a group of deep drilling fields (DDFs). The DDFs are a critical piece of three key aspects of the LSST Dark Energy Science Collaboration (DESC) cosmological measurements: they provide a required calibration for photometric redshifts and weak gravitational lensing measurements and they directly contribute to cosmological constraints from the most distant type Ia supernovae. We present a set of cohesive DDF strategies fulfilling science requirements relevant to DESC and following the guidelines of the Survey Cadence Optimization Committee. We propose a method to estimate the observing strategy parameters and we perform simulations of the corresponding surveys. We define a set of metrics for each of the science case to assess the performance of the proposed observing strategies. We show that the most promising results are achieved with deep rolling surveys characterized by two sets of fields: ultradeep fields (z<1.1) observed at a high cadence with a large number of visits over a limited number of seasons; deep fields (z<0.7), observed with a cadence of ~3 nights for ten years. These encouraging results should be confirmed with realistic simulations using the LSST scheduler. A DDF budget of ~8.5% is required to design observing strategies satisfying all the cosmological requirements. A lower DDF budget lead to surveys that either do not fulfill photo-z/WL requirements or are not optimal for SNe Ia cosmology.
Data science pipelines inform and influence many daily decisions, from what we buy to who we work for and even where we live. When designed incorrectly, these pipelines can easily propagate social inequity and harm. Traditional solutions are technical in nature; e.g., mitigating biased algorithms. In this vision paper, we introduce a novel lens for promoting responsible data science using theories of behavior change that emphasize not only technical solutions but also the behavioral responsibility of practitioners. By integrating behavior change theories from cognitive psychology with data science workflow knowledge and ethics guidelines, we present a new perspective on responsible data science. We present example data science interventions in machine learning and visual data analysis, contextualized in behavior change theories that could be implemented to interrupt and redirect potentially suboptimal or negligent practices while reinforcing ethically conscious behaviors. We conclude with a call to action to our community to explore this new research area of behavior change interventions for responsible data science.
Ricardo Villalobos, Héctor López, Nimrod Vázquez
et al.
The active sound navigation and ranging (SONAR) transmission system emits acoustic pulses underwater using a wave generator, a SONAR power amplifier (SPA), and a projector. The acoustic pulse travel in the direction of the target and return as an echo to a hydrophone to learn the range or speed of the object. Often the same device is used as a hydrophone and a projector; in this context, it is known as a transducer. In order to obtain a maximum range of detection in the SONAR, it is desirable to generate the maximum amount of acoustic power until the point in which the echo can be detectable in an atmosphere with non-wished noise. Therefore, a high value of source level (SL) is required that depends largely on the value of electrical power applied to the transducer (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></semantics></math></inline-formula>). However, when trying to obtain the maximum range of detection in the SONAR system there are the following three peculiar limitations that affect performance: The cavitation, the reverberation, and the effect of interaction in the near field. In this paper, an experimental measurement methodology is presented to detect the cavitation effects in a tonpilz-type transducer for an active SONAR transmission system using a transducer as a projector and a calibrated hydrophone in a hydroacoustic tank by measuring the parameters of total harmonic distortion of the fundamental waveform (THD-F) of the generated acoustic pulse, transmitting voltage response (TVR) to characterize the system and sound pressure level (SPL) that indicates the intensity of sound at a given distance. Whereas the reverberation and the interaction effect in the near field are objects of other study cases. A 570.21 W and THD-F < <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>5</mn><mo>%</mo></mrow></semantics></math></inline-formula> switched-mode power amplifier (SMPA) prototype was developed to excite the electroacoustic transducer employing a full-bridge inverter (FBI) topology and a digital controller using a field-programmable gate array (FPGA) for unipolar sine pulse width modulation (SPWM) to generate a continuous wave (CW) acoustic pulse at a frequency 11.6 kHz. The results obtained show that from the level of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>e</mi></mrow></msub><mo>=</mo><mn>196.05</mn></mrow></semantics></math></inline-formula> W with the transducer at 1 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">m</mi></mrow></semantics></math></inline-formula> of depth, the value of THD-F increases significantly while the behavior of the TVR and SPL parameters is affected since it is not as expected and is attributed when cavitation occurs.
In marine engineering, the installation of structures inevitably involves the process of water exit. This paper studies the vertical force, the shape of the free surface, and the evolution of the water entrained in a cavity in the process of lifting a structure, so as to provide guidance for practical engineering operations. Using a 1:8 experimental model, this paper derives the governing equations based on the Reynolds-averaged Navier–Stokes approach and uses the volume of fluid method to capture the shape change of the free surface. The vertical forces obtained at different lifting speeds are found to be in good agreement with the results of previous model tests. The results show that the numerical simulation method and mesh generation described in this paper can simulate the changes in the physical quantities associated with the structure in the process of water exit. The vertical force on the structure increases nonlinearly as the lifting speed rises, and the maximum lifting speed is conservatively estimated to be 0.034 m/s using the Det Norske Veritas recommended method. The maximum vertical force occurs as the whole structure leaves the water. The water entrained in the structure is mainly located at the sides and bottom. The lifting velocity plays an important role in the water exit process. The water exit force first increases and then decreases to a stable value as the lifting velocity increases, while the maximum water exit force increases nonlinearly.
<p>This study determined the level of acceptability of the e-learning module in Seamanship 2A as well as its strengths and weaknesses. The respondents of this study were the 286 randomly chosen Bachelor of Science in Marine Transportation students who took up Seamanship 2A during the first semester of the school year 2021-2022 and five purposively chosen experts in the field of maritime education, Information and Communication Technology, and production of learning materials. This study utilized a two-part research instrument where the first part was a 30-item Likert-type questionnaire, while the second part consisted of two open-ended questions. It utilized a survey research design. The results show that the students and the experts found the e-learning module in Seamanship 2A to have high acceptability in general and in terms of appearance, learning activities, evaluation procedure, ease of use, and usefulness. According to students, the strengths of the e-learning module in Seamanship 2A were: accessible, convenient, easy to understand, informative, relevant, sufficient content, user-friendly, several varied sources available, self-paced, well-organized, efficient, and systematic. Meanwhile, its weaknesses include the need for internet access, incomprehensive discussion of the contents, unreliable/unstable site, lack of human interaction, lack of hands-on experience, difficulty in using the site, misaligned lesson content and quizzes, excessive screen time, and availability of gadgets. It is recommended that the e-learning module in Seamanship 2A may be improved based on its strengths and weaknesses. Future researchers may conduct similar studies on other subject areas, look into longitudinal research or determine the effectiveness of the e-learning module.</p><p><strong><br /></strong></p><p><strong>Received: 12 October 2023 </strong></p><p><strong>Accepted: 02 December 2023 </strong></p><p><strong>Published: 12 December 2023</strong></p>
Udayan Khurana, Kavitha Srinivas, Sainyam Galhotra
et al.
The recent efforts in automation of machine learning or data science has achieved success in various tasks such as hyper-parameter optimization or model selection. However, key areas such as utilizing domain knowledge and data semantics are areas where we have seen little automation. Data Scientists have long leveraged common sense reasoning and domain knowledge to understand and enrich data for building predictive models. In this paper we discuss important shortcomings of current data science and machine learning solutions. We then envision how leveraging "semantic" understanding and reasoning on data in combination with novel tools for data science automation can help with consistent and explainable data augmentation and transformation. Additionally, we discuss how semantics can assist data scientists in a new manner by helping with challenges related to trust, bias, and explainability in machine learning. Semantic annotation can also help better explore and organize large data sources.
Ontologies play a critical role in Semantic Web technologies by providing a structured and standardized way to represent knowledge and enabling machines to understand the meaning of data. Several taxonomies and ontologies have been generated, but individuals target one domain, and only some of those have been found expensive in time and manual effort. Also, they need more coverage of unconventional topics representing a more holistic and comprehensive view of the knowledge landscape and interdisciplinary collaborations. Thus, there needs to be an ontology covering Science and Technology and facilitate multidisciplinary research by connecting topics from different fields and domains that may be related or have commonalities. To address these issues, we present an automatic Science and Technology Ontology (S&TO) that covers unconventional topics in different science and technology domains. The proposed S&TO can promote the discovery of new research areas and collaborations across disciplines. The ontology is constructed by applying BERTopic to a dataset of 393,991 scientific articles collected from Semantic Scholar from October 2021 to August 2022, covering four fields of science. Currently, S&TO includes 5,153 topics and 13,155 semantic relations. S&TO model can be updated by running BERTopic on more recent datasets
AbstractComparative biologists have typically used one or more of the following methods to assist in evaluating the proposed functional and performance significance of individual traits: comparative phylogenetic analysis, direct interspecific comparison among species, genetic modification, experimental alteration of morphology (for example by surgically modifying traits), and ecological manipulation where individual organisms are transplanted to a different environment. But comparing organisms as the endpoints of an evolutionary process involves the ceteris paribus assumption: that all traits other than the one(s) of interest are held constant. In a properly controlled experimental study, only the variable of interest changes among the groups being compared. The theme of this paper is that the use of robotic or mechanical models offers an additional tool in comparative biology that helps to minimize the effect of uncontrolled variables by allowing direct manipulation of the trait of interest against a constant background. The structure and movement pattern of mechanical devices can be altered in ways not possible in studies of living animals, facilitating testing hypotheses of the functional and performance significance of individual traits. Robotic models of organismal design are particularly useful in three arenas: (1) controlling variation to allow modification only of the trait of interest, (2) the direct measurement of energetic costs of individual traits, and (3) quantification of the performance landscape. Obtaining data in these three areas is extremely difficult through the study of living organisms alone, and the use of robotic models can reveal unexpected effects. Controlling for all variables except for the length of a swimming flexible object reveals substantial non-linear effects that vary with stiffness. Quantification of the swimming performance surface reveals that there are two peaks with comparable efficiency, greatly complicating the inference of performance from morphology alone. Organisms and their ecological interactions are complex, and dissecting this complexity to understand the effects of individual traits is a grand challenge in ecology and evolutionary biology. Robotics has great promise as a “comparative method,” allowing better-controlled comparative studies to analyze the many interacting elements that make up complex behaviors, ecological interactions, and evolutionary histories.
The seafloor soil is characterized by high water content, strong compressibility, and low shear strength. Deep-sea mining vehicles (DSMV) are prone to sinking when walking on the surface of the soil, which will cause significant reduction in traction performance. Therefore, it is necessary to study the sinkage performance. The track is usually considered the travelling mechanism of the DSMV, and the track plate is an important part of the movement system. The study of the interaction between the track plate and the soil is of great significance to the study of the DSMV’s sinkage performance. In this study, firstly, based on the in situ seafloor soil samples of 1000 m in a region of the South China Sea collected by a box sampler, the physical and mechanical parameters of soil were measured by indoor geotechnical instruments. Secondly, an elastoplastic soil numerical model similar to that of in situ soil was established. Based on coupled Eulerian-Lagrangian (CEL) method, a numerical model of the interaction between the track plate and soil was established. Considering the dynamic process, the structure of the track plate and the physical and mechanical properties of the soil, the numerical simulation were carried out under different conditions, such as different dynamic loading, the plate structural parameters and the soil physical and mechanical properties. It is found that the plate-sinkage curve were significantly influenced by these factors. The findings are as follows, firstly, with the increase in the pressure loading rate, the soil sinkage decreasing at the same pressure. On the other hand, with the increase in velocity, soil flow was accelerated, and the nonlinear relationship between resistance and velocity became more obvious; the L/B ratio of different track plates affects the variation law of the curve, and the maximum sinkage gradually decreases as the ratio of L/B increases; with the increase in the grouser height, the maximum sinkage gradually decreases, and the pressure-sinkage curve changes obviously with the grouser type; and different soil physical and mechanical properties affect the variation of pressure-sinkage curve. Innovatively, the heterogeneous soil stress distribution mode was obtained through the fitting function and Python secondary development. This study can provide a reference for studying the sinkage performance of the DSMV.