bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design, modeling, and manufacturing of a novel robust gripper-based climbing robot: KharazmBot
Authors: Boomeri Vahid , Tourajizadeh Hami , Askarian Hamid Reza , Pourebrahim Sina 
Published: May 2023

AbstractThere are a lot of high-height structures that should be inspected or manipulated frequently due to maintenance purposes. According to the safety considerations and time or cost limitations, substituting the human operator with an automatic robot is inevitable. The main objective of this paper is to design and manufacture a novel climbing robot equipped with grip-based locomotion system which can climb through scaffold structures and trusses to accomplish inspectional and operational tasks. The proposed robot has good maneuverability and stability. The proposed robot is manufactured in order to verify the simulation results with experimental data. The chassis and its corresponding grippers are designed first, and the corresponding model of the system is extracted. This model is used then for designing the controlling strategy of the system. The path planning of the robot is conducted to realize the climbing process by the robot during several steps in an optimum way. The prototype of the proposed robot is manufactured at Kharazmi University called KharazmBot. Experimental results not only show the capability of the manufactured robot toward ascending the mentioned structures but also prove its high stability as a result of its designed gripper and also its good maneuverability as a result of its over-actuated mechanism. Thus, it is concluded that the designed and manufactured climbing robot of this paper can successfully ascend through the pipes and trusses and perform a desired inspectional or operational task with good accuracy and safety while its stability is also satisfied.
A low-cost indoor positioning system based on data-driven modeling for robotics research and education
Authors: Ou Junlin , Hong Seong Hyeon , Kyzer Tristan , Yang Haizhou , Zhou Xianlian , Wang Yi 
Published: May 2023

AbstractThis paper presents a low-cost, accurate indoor positioning system that integrates image acquisition and processing and data-driven modeling algorithms for robotics research and education. Multiple overhead cameras are used to obtain normalized image coordinates of ArUco markers, and a new procedure is developed to convert them to the camera coordinate frame. Various data-driven models are proposed to establish a mapping relationship between the camera and the world coordinates. One hundred fifty data pairs in the camera and world coordinates are generated by measuring the ArUco marker at different locations and then used to train and test the data-driven models. With the model, the world coordinate values of the ArUco marker and its robot carrier can be determined in real time. Through comparison, it is found that a straightforward polynomial regression outperforms the other methods and achieves a positioning accuracy of about 1.5 cm. Experiments are also carried out to evaluate its feasibility for use in robot control. The developed system (both hardware and algorithms) is shared as an open source and is anticipated to contribute to robotic studies and education in resource-limited environments and underdeveloped regions.
Control of port-Hamiltonian differential-algebraic systems and applications
Authors: Mehrmann Volker , Unger Benjamin 
Published: May 2023

We discuss the modelling framework of port-Hamiltonian descriptor systems and their use in numerical simulation and control. The structure is ideal for automated network-based modelling since it is invariant under power-conserving interconnection, congruence transformations and Galerkin projection. Moreover, stability and passivity properties are easily shown. Condensed forms under orthogonal transformations present easy analysis tools for existence, uniqueness, regularity and numerical methods to check these properties.After recalling the concepts for general linear and nonlinear descriptor systems, we demonstrate that many difficulties that arise in general descriptor systems can be easily overcome within the port-Hamiltonian framework. The properties of port-Hamiltonian descriptor systems are analysed, and time discretization and numerical linear algebra techniques are discussed. Structure-preserving regularization procedures for descriptor systems are presented to make them suitable for simulation and control. Model reduction techniques that preserve the structure and stabilization and optimal control techniques are discussed.The properties of port-Hamiltonian descriptor systems and their use in modelling simulation and control methods are illustrated with several examples from different physical domains. The survey concludes with open problems and research topics that deserve further attention.
Improving school lunch menus with multi-objective optimisation: nutrition, cost, consumption and environmental impacts
Authors: Stern Alexandra L , Levine Stephen , Richardson Scott A , Blackstone Nicole Tichenor , Economos Christina , Griffin Timothy S 
Published: May 2023

AbstractObjective:To support school foods programmes by evaluating the relationship between nutritional quality, cost, student consumption and the environmental impacts of menus.Design:Using linear programming and data from previously served menu items, the relationships between the nutritional quality, cost, student consumption and the environmental impacts of lunch menus were investigated. Optimised lunch menus with the maximum potential student consumption and nutritional quality and lowest costs and environmental impacts were developed and compared with previously served menus (baseline).Setting:Boston Public Schools (BPS), Boston Massachusetts, USA.Participants:Menu items served on the 2018–2019 BPS lunch menu (n 142).Results:Using single-objective models, trade-offs were observed between most interests, but the use of multi-objective models minimised these trade-offs. Compared with the current weekly menus offered, multi-objective models increased potential caloric intake by up to 27 % and Healthy Eating Index scores by up to 19 % and reduced costs and environmental impacts by up to 13 % and 71 %, respectively. Improvements were made by reducing the frequency of beef and cheese entrées and increasing the frequency of fish and legume entrées on weekly menus.Conclusions:This work can be extrapolated to monthly menus to provide further direction for school districts, and the methods can be employed with different recipes and constraints. Future research should test the implementation of optimised menus in schools and consider the broader implications of implementation.
Identity, memory, and homeland: in conversation with Tsering Wangmo Dhompa, a Tibetan author and poet in exile
Authors: D'Rozario Priyanka 
Published: May 2023

AbstractThe annexation of Tibet into the People's Republic of China in the 1950s led to an exodus of nearly 80,000 Tibetans along with the fourteenth Dalai Lama Tenzin Gyatso. Since then, thousands of Tibetans have taken refuge in the neighboring countries. Many live as refugees in different parts of the world today. Although the Tibetan refugee community has emerged as a successful model for other displaced communities, the individual struggles of these refugees in foreign lands cannot be underestimated. Dhompa's book A Home in Tibet shines a light on this other side of their exilic existence by raising questions about identity, home, country, and memory. It outlines the hardships, confusion, and contestations that Tibetans face on a daily basis. After a short introduction to provide context, this article reports a conversation with Tsering Wangmo Dhompa, which grippingly addresses these issues.
Determination of Spatial Scale in Martian Landscape Images Acquired by the Curiosity Rover, and Viewing Image Scale and Target Chemistry Using the ASIC Website
Authors: Goetz Walter , Bruns Michael , Thoma Stephan , Pardowitz Iancu , Stein Thomas C. 
Published: May 2023

AbstractIn this paper we describe a method to compute spatial scales for images acquired by NASA's Mars Curiosity rover (Mars Science Laboratory, MSL). The method is based on the assumption that the rover stands on an infinite plane that may have any orientation with respect to the local gravity vector. While not new, it is the first time that this method is systematically applied to Martian images acquired by a lander. A continuously run software pipeline processes the images acquired by the rover within a 20 m radius, adds approximate scalebars to the raw images, and generates, whenever possible, rectified (warped) versions of those images. The products of this software pipeline and the chemical compositions of relevant rover science targets from NASA's Planetary Data System archive, are made available to the public via the Approximate Scale for Images and Chemistry website, which has been developed in collaboration with the Planetary Data System Analyst's Notebook for the MSL mission. Hyperlinks connect the two resources.
Assessing Three Perfect Prognosis Methods for Statistical Downscaling of Climate Change Precipitation Scenarios
Authors: Legasa M. N. , Thao S. , Vrac M. , Manzanas R. 
Published: May 2023

AbstractUnder the perfect prognosis approach, statistical downscaling methods learn the relationships between large‐scale variables from reanalysis and local observational records. These relationships are subsequently applied to downscale future global climate model (GCM) simulations in order to obtain projections for the local region and variables of interest. However, the capability of such methods to produce future climate change signals consistent with those from the GCM, often referred to as transferability, is an important issue that remains to be carefully analyzed. Using the EC‐Earth GCM and focusing on precipitation, we assess the transferability of generalized linear models, convolutional neural networks and a posteriori random forests (APRFs). We conclude that APRFs present the best overall performance for the historical period, and future local climate change signals consistent with those projected by EC‐Earth. Moreover, we show how a slight modification of APRFs can greatly improve the temporal consistency of the downscaled series.
Nitrous Oxide Dynamics in the Siberian Arctic Ocean and Vulnerability to Climate Change
Authors: Wild Birgit , Ray Nicholas E. , Lett Céline , Davies Amelia Jane , Kirillova Elena , Holmstrand Henry , Klevantceva Elizaveta , Osadchiev Alexander , Gangnus Ivan , Yakushev Evgeniy , Kosmach Denis , Dudarev Oleg , Gustafsson Örjan , Semiletov Igor , Brüchert Volker 
Published: May 2023

AbstractNitrous oxide (N2O) is a strong greenhouse gas and stratospheric ozone‐depleting substance. Around 20% of global emissions stem from the ocean, but current estimates and future projections are uncertain due to poor spatial coverage over large areas and limited understanding of drivers of N2O dynamics. Here, we focus on the extensive and particularly data‐lean Arctic Ocean shelves north of Siberia that experience rapid warming and increasing input of land‐derived nitrogen with permafrost thaw. We combine water column N2O measurements from two expeditions with on‐board incubation of intact sediment cores to assess N2O dynamics and the impact of land‐derived nitrogen. Elevated nitrogen concentrations in water column and sediments were observed near large river mouths. Concentrations of N2O were only weakly correlated with dissolved nitrogen and turbidity, reflecting particulate matter from rivers and coastal erosion, and correlations varied between river plumes. Surface water N2O concentrations were on average close to equilibrium with the atmosphere, but varied widely (N2O saturation 38%–180%), indicating strong local N2O sources and sinks. Water column N2O profiles and low sediment‐water N2O fluxes do not support strong sedimentary sources or sinks. We suggest that N2O dynamics in the region are influenced by water column N2O consumption under aerobic conditions or in anoxic microsites of particles, and possibly also by water column N2O production. Changes in biogeochemical and physical conditions will likely alter N2O dynamics in the Siberian Arctic Ocean over the coming decades, in addition to reduced N2O solubility in a warmer ocean.
On Body and Off‐Body Performance Analysis of an Ashoka Tree Shaped Wearable Textile Antenna for Biomedical and Military Applications
Authors: Mulaparti Meena Kumari , Ratnakumari U. V. , Satyannarayana M. 
Published: May 2023

AbstractIn this paper an Ashoka tree shaped wearable textile antenna for biomedical and military applications working at 2.4 GHz, 9.04 GHz is investigated and analyzed. The designed antenna has the size of 34 × 40 × 1 mm3. To obtain a wide bandwidth 0.5 × 40 mm2 partial ground plane is used. The lightweight jean material is employed as a non‐conductive dielectric substance with a εr of 1.7 and a substrate height of 1 mm to define the wearable applications. Examining the surface current and actualizing the conductivity of the radiating elements are performed. Full‐wave EM simulation and experimental results are carried out at 30°,60°, and 90° under various bending conditions, both in free space and close to the human body. The suggested antenna performs satisfactorily in terms of gain and specific absorption rate. When worn on the body, the final design offers a peak gain of 7.6 dBi and an efficiency of 94.7%. Findings from simulations using CST Microwave Studio and measurements are quite close. These characteristics show that the suggested antenna is a solid contender for wearable applications that are both off‐ and on‐body. Due to its compatibility, adaptability in structure design and shape, excellent performance at various angles, human safety, miniaturization, power consumption, etc., this Ashoka tree‐shaped antenna can be significantly used in military jackets and in biomedical applications.
Revealing the Extent of Submarine Permafrost and Gas Hydrates in the Canadian Arctic Beaufort Sea Using Seismic Reflection Indicators
Authors: Grob H. , Riedel M. , Duchesne M. J. , Krastel S. , Bustamante J. , Fabien‐Ouellet G. , Jin Y. K. , Hong J. K. 
Published: May 2023

AbstractThe Canadian Arctic Southern Beaufort Sea is characterized by prominent relict submarine permafrost and gas hydrate occurrences formed by subaerial exposure during extensive glaciations in Pliocene and Pleistocene. Submarine permafrost is still responding to the thermal change as a consequence of the marine transgression that followed the last glaciation. Submarine permafrost is still underexplored and is currently the focus of several research projects as its degradation releases greenhouse gases that contribute to climate change. In this study, seismic reflection indicators are used to investigate the presence of submarine permafrost and gas hydrates on the outer continental shelf where the base of permafrost is expected to cross‐cut geological layers. To address the challenges of marine seismic data collected in shallow water environments, we utilize a representative synthetic model to assess the data processing and the detection of submarine permafrost and gas hydrate by seismic data. The synthetic model allows us to minimize the misinterpretation of acquisition and processing artifacts. In the field data, we identify features along with characteristics arising from the top and base of submarine permafrost and the base of the gas hydrate stability zone. This work shows the distribution of the present submarine permafrost along the southern Canadian Beaufort Sea region and confirms its extension to the outer continental shelf. It supports the general shape suggested by previous works and previously published numerical models.
Detections of Infrasound Waves From Water Discharges at a Hydroelectric Dam: Implementation of Timely Warnings for Unexpected Discharge Events
Authors: Che Il‐Young , Kim Inho , Park Junghyun , Kim Byung‐Il , Kim Kwangsu 
Published: May 2023

AbstractWater discharges at hydroelectric dams on the Imjin River, which flows through North and South Korea, generate abrupt water level increases downstream. We assessed infrasound signals from water discharges using an infrasound array located ∼32 km from the source and applied infrasound detection in a flash flood alert system. Using infrasound signals, there was a 79% detection rate for 48 water level increase events occurring in the river downstream during a 14‐year period (2008–2021). The detected signals had a low amplitude, long duration, and broad frequency range (0.5–15 Hz). The energy curves of the detected infrasound signals for selected events showed good correlations with the onset times and water level variations in water level records. These results demonstrate that infrasound monitoring can serve as a practical early warning system for impending flash floods resulting from unnoticed water discharges or sudden debris flows in mountainous regions.
Soft X‐Ray Imaging of Earth's Dayside Magnetosheath and Cusps Using Hybrid Simulations
Authors: Ng J. , Walsh B. M. , Chen L.‐J. , Omelchenko Y. 
Published: May 2023

AbstractInteractions between solar wind ions and neutral hydrogen atoms in Earth's exosphere can lead to the emission of soft X‐rays. Upcoming missions such as SMILE and LEXI aim to use soft X‐ray imaging to study the global structure of the magnetosphere. Although the magnetosheath and dayside magnetopause can often be driven by kinetic physics, it has typically been omitted from fluid simulations used to predict X‐ray emissions. We study the possible results of soft X‐ray imaging using hybrid simulations under quasi‐radial interplanetary magnetic fields, where ion‐ion instabilities drive ultra‐low frequency foreshock waves, leading to turbulence in the magnetosheath, affecting the dynamics of the cusp and magnetopause. We simulate soft X‐ray emission to determine what may be seen by missions such as LEXI, and evaluate the possibility of identifying kinetic structures. While kinetic structures are visible in high‐cadence imaging, current instruments may not have the time resolution to discern kinetic signals.
Undulated Shock Surface Formed After a Shock–Discontinuity Interaction
Authors: Zhou Yufei , Shen Chao , Ji Yong 
Published: May 2023

AbstractShock ripples and shock–discontinuity interactions (SDIs) have long been proposed to explain the frequent occurrence of high‐speed jets (HSJs) in the magnetosheath; however, there is no direct observational evidence for either of them occurring near a shock. Herein, we report a large‐scale, long‐duration undulated quasi‐perpendicular shock surface that is capable of generating HSJs. Based on the curvatures estimated for the shock undulation and for a nearby hot flow anomaly (HFA), we suggest that the shock ripple mechanism and the SDI mechanism combine to generate HSJs, that is, during an SDI, shock undulations and an upstream HFA form simultaneously, and the solar wind between them is deflected by the undulation into jets. The HSJs, discontinuity, and HFA are then convected downstream. An HSJ consistent with our mechanism in another event is presented.
Traveling Ionospheric Disturbances Induced by the Secondary Gravity Waves From the Tonga Eruption on 15 January 2022: Modeling With MESORAC‐HIAMCM‐SAMI3 and Comparison With GPS/TEC and Ionosonde Data
Authors: Vadas Sharon L. , Figueiredo Cosme , Becker Erich , Huba J. D. , Themens David R. , Hindley Neil P. , Mrak Sebastijan , Galkin Ivan , Bossert Katrina 
Published: May 2023

AbstractWe simulate the gravity waves (GWs) and traveling ionospheric disturbances (TIDs) created by the Hunga Tonga‐Hunga Ha'apai (hereafter “Tonga”) volcanic eruption on 15 January 2022 at ∼04:15 UT. We calculate the primary GWs and forces/heatings generated where they dissipate with MESORAC, the secondary GWs with HIAMCM, and the TIDs with SAMI3. We find that medium and large‐scale TIDs (MSTIDs and LSTIDs) are induced by the secondary GWs, with horizontal phase speeds cH ≃ 100–750 m/s, horizontal wavelengths λH ≃ 600–6,000 km, and ground‐based periods τr ≃ 30 min to 3 hr. The LSTID amplitudes over New Zealand are ≃2–3 TECU, but decrease sharply ≃ 5,000 km from Tonga. The LSTID amplitudes are extremely small over Australia and South Africa because body forces create highly asymmetric GW fields and the GWs propagate perpendicular to the magnetic field there. We analyze the TIDs from SAMI3 and find that a 30 min detrend window eliminates the fastest far‐field LSTIDs. We analyze the GPS/TEC via detrending with 2–3 hr windows, and find that the fastest LSTIDs reach the US and South America at ∼8:30–9:00 UT with cH ≃ 680 m/s, λH ≃ 3,400 km, and τr ≃ 83 min, in good agreement with model results. We find good agreement between modeled and observed TIDs over New Zealand, Australia, Hawaii, Japan and Norway. The observed F‐peak height, hmF2, drops by ≃ 110–140 km over the western US with a 2.8 hr periodicity from 8:00 to 13:00 UT. We show that the Lamb waves (LWs) observed by AIRS with λH = 380 km have amplitudes that are ≃ 2.3% that of the primary GWs at z ≃ 110 km. We conclude that the observed TIDs can be fully explained by secondary GWs rather than by “leaked” LWs.
Absence of near-ambient superconductivity in LuH2±xNy
Authors: Ming Xue , Zhang Ying-Jie , Zhu Xiyu , Li Qing , He Chengping , Liu Yuecong , Huang Tianheng , Liu Gan , Zheng Bo , Yang Huan , Sun Jian , Xi Xiaoxiang , Wen Hai-Hu 
Published: May 2023

AbstractA recent study demonstrated near-ambient superconductivity in nitrogen-doped lutetium hydride1. This stimulated a worldwide interest in exploring room-temperature superconductivity at low pressures. Here, by using a high-pressure and high-temperature synthesis technique, we have obtained nitrogen-doped lutetium hydride (LuH2±xNy), which has a dark-blue colour and a structure with the space group$$Fm\bar{3}m$$Fm3¯mas evidenced by X-ray diffraction. This structure is the same as that reported in ref. 1, with a slight difference in lattice constant. Raman spectroscopy of our samples also showed patterns similar to those observed in ref. 1. Energy-dispersive X-ray spectroscopy confirmed the presence of nitrogen in the samples. We observed a metallic behaviour from 350 K to 2 K at ambient pressure. On applying pressures from 2.1 GPa to 41 GPa, we observed a gradual colour change from dark blue to violet to pink-red. By measuring the resistance at pressures ranging from 0.4 GPa to 40.1 GPa, we observed a progressively improved metallic behaviour; however, superconductivity was not observed above 2 K. Temperature dependence of magnetization at high pressure shows a very weak positive signal between 100 K and 320 K, and the magnetization increases with an increase in magnetic field at 100 K. All of these are not expected for superconductivity above 100 K. Thus, we conclude the absence of near-ambient superconductivity in this nitrogen-doped lutetium hydride at pressures below 40.1 GPa.