搜索结果：JEMS

This is a collection of papers presented by the JEM-EUSO Collaboration at the 39th International Cosmic Ray Conference (ICRC 2025) (Geneva, Switzerland, July 14--24, 2025).

Autonomous free-flyers play a critical role in intravehicular tasks aboard the International Space Station (ISS), where their precise docking under sensing noise, small actuation mismatches, and environmental variability remains a nontrivial challenge. This work presents a reinforcement learning (RL) framework for six-degree-of-freedom (6-DoF) docking of JAXA's Int-Ball2 robot inside a high-fidelity Isaac Sim model of the Japanese Experiment Module (JEM). Using Proximal Policy Optimization (PPO), we train and evaluate controllers under domain-randomized dynamics and bounded observation noise, while explicitly modeling propeller drag-torque effects and polarity structure. This enables a controlled study of how Int-Ball2's propulsion physics influence RL-based docking performance in constrained microgravity interiors. The learned policy achieves stable and reliable docking across varied conditions and lays the groundwork for future extensions pertaining to Int-Ball2 in collision-aware navigation, safe RL, propulsion-accurate sim-to-real transfer, and vision-based end-to-end docking.

The JEM-EUSO (Joint Exploratory Missions for Extreme Universe Space Observatory) collaboration is an international initiative studying ultra-high-energy cosmic rays and related phenomena. These particles, with energies exceeding 10$^{20}$~eV, provide insights into extreme astrophysical processes but remain challenging to detect due to their low flux. At the heart of JEM-EUSO's technology is an ultra-fast, highly sensitive UV camera capable of detecting EASs in the atmosphere with exceptional spatial and temporal resolution. A dedicated Cherenkov camera has been developed to evaluate the viability of the Earth-skimming technique from high altitudes. Fluorescence and Cherenkov detectors can be used together to create a hybrid detection surface. This innovative approach enables detailed studies of fluorescence and Cherenkov light from cosmic ray and neutrino interactions. The JEM-EUSO technology will allow for observations from space to significantly increase the exposure to these rare phenomena. The collaboration employs a multi-platform strategy with ground-based experiments like EUSO-TA calibrating detection systems and validating models, and balloon-borne missions such as EUSO-Bal

Ranking a set of items based on their relevance to a given query is a core problem in search and recommendation. Transformer-based ranking models are the state-of-the-art approaches for such tasks, but they score each query-item independently, ignoring the joint context of other relevant items. This leads to sub-optimal ranking accuracy and high computational costs. In response, we propose Cross-encoders with Joint Efficient Modeling (CROSS-JEM), a novel ranking approach that enables transformer-based models to jointly score multiple items for a query, maximizing parameter utilization. CROSS-JEM leverages (a) redundancies and token overlaps to jointly score multiple items, that are typically short-text phrases arising in search and recommendations, and (b) a novel training objective that models ranking probabilities. CROSS-JEM achieves state-of-the-art accuracy and over 4x lower ranking latency over standard cross-encoders. Our contributions are threefold: (i) we highlight the gap between the ranking application's need for scoring thousands of items per query and the limited capabilities of current cross-encoders; (ii) we introduce CROSS-JEM for joint efficient scoring of multiple

This is a collection of papers presented by the JEM-EUSO Collaboration at the 38th International Cosmic Ray Conference (Nagoya, Japan, July 26-August 3, 2023)

The JEM-EUSO program is focused on observations of Ultra High Energy Cosmic Rays (UHECRs) from space. For this purpose, a series of detectors based on multi-anode photomultiplier tubes with a time resolution of the order of $μ$s have been developed. The detectors work in the UV band to search for ultra-fast signals produced in the Earth's atmosphere during an Extensive Air Shower (EAS) development. Since 2014, various signals have been detected by ground-, ballon- and space-based detectors. A single photodetector module consists of a focal surface with a matrix of 36 multi-anode photomultiplier tubes containing 2304 pixels. The detector's structure allows probing it during the mission if a point-like source emitting in a UV band is in the field of view. In this work, we present the idea and results of calibration of the JEM--EUSO detectors using signals from stars registered during sky observations from the ground. Registered signals can be used for the absolute calibration of the detectors and for testing the detector condition during observations. The presented analysis is based on the data taken by the EUSO-TA and EUSO-TA2 experiments.

JEM--EUSO is an international program for the development of space-based Ultra-High Energy Cosmic Ray observatories. The program consists of a series of missions which are either under development or in the data analysis phase. All instruments are based on a wide-field-of-view telescope, which operates in the near-UV range, designed to detect the fluorescence light emitted by extensive air showers in the atmosphere. We describe the simulation software ESAFin the framework of the JEM--EUSO program and explain the physical assumptions used. We present here the implementation of the JEM--EUSO, POEMMA, K--EUSO, TUS, Mini--EUSO, EUSO--SPB1 and EUSO--TA configurations in ESAF. For the first time ESAF simulation outputs are compared with experimental data.

The Joint Experiment Missions for Extreme Universe Observatory comprises a collection of complementary missions dedicated to pioneering technologies and techniques for a future space-based multi-messenger observatory which will have sufficient sensitivity and exposure to measure properties of extremely rare ultra-high energy (E>50 EeV) cosmic rays and very high energy (E>100 PeV) neutrinos. Here we describe a general-purpose software framework designed to facilitate detailed simulation and reconstruction of events observed by the various missions using both detection of fluorescence and Cherenkov light produced when cosmic ray or neutrino-induced extensive air showers traverse Earth's atmosphere. The software builds on a framework developed by the Pierre Auger Collaboration. We describe the techniques used to organize contributions from numerous collaborators, manage an abundance of configuration information, and provide simple access to time-dependent detector and atmospheric information. We also explain how we support a multitude of computing platforms, provide fast installation and maintain the broad testing coverage required for stability of the large and heterogeneous co

Ultra High Energy Cosmic Rays (UHECRs) offer a unique chance to study the universe at energies inaccessible by man-made accelerators. Observations by ground based observatories have clarified several characteristics of these particles, but their origin, nature, and acceleration mechanisms are still unclear, mostly due to their extremely low flux. Space-based observatories have the potential for an increase in statistics, up to several orders of magnitude, and would be able to cover the whole sky, allowing for a direct comparison of spectra and direction of arrival, but the detector design poses several formidable technical challenges. The JEM-EUSO program has been addressing this problem, trying to open the road of space-based UHECR observations. Several missions have already been completed (on the ground: EUSO-TA; with stratospheric ballons: EUSO-Balloon, EUSO-SPB1 and EUSO-SPB2; in space: TUS\cite{Klimov2017}, MINI-EUSO). Others are under study (K-EUSO) or proposed for the next decade (POEMMA)\cite{Olinto_2021}. In this work we report on the status of the JEM-EUSO program and the technology developed so far.

Compilation of papers presented by the JEM-EUSO Collaboration at the 37th International Cosmic Ray Conference (ICRC), held on July 12-23, 2021 (online) in Berlin, Germany.

A new AI-powered blood test could give people a remarkably early warning of serious heart and circulation problems。 Developed by researchers at the University of Hong Kong, CardiOmicScore analyzes thousands of proteins and metabolites to estimate the risk of six major cardiovascular diseases, including heart attack, stroke, heart failure, and atria

The asteroid that wiped out the dinosaurs was likely an exceptionally rare CO chondrite from a distant region of the solar system。 Its unusual chemistry suggests that planet-cooling dust and debris, rather than sulfur inside the asteroid, may have delivered the deadliest blow

Starlink has a Texas factory but also makes routers in Vietnam

Scientists say new technologies have reopened the debate over whether Mars could someday be terraformed, turning a once impossible idea into a serious research topic。 Before anyone tries to reshape the Red Planet, though, researchers say we must understand the risks, including what might be lost if Mars already harbors its own forms of life

The new full-size flagship SUV starts at $87,700 when it goes on sale in Q4

Google's and Reddit's use of DMCA to fight web scraper is bizarre, expert says