Abstract The focus of this research is the investigation of the anisotropic properties of cold-rolled and hot-rolled steel sheets, with particular emphasis on how this anisotropy varies as a function of material thickness. For this purpose, the acoustic emission (AE) method is applied, which is a highly sensitive, real-time, non-destructive testing technique. This method enables the detection of various microstructural phenomena—such as the initiation of microcracks, dislocation motion, and other internal structural rearrangements—even at their early stages. Through the analysis of AE signals, a detailed insight can be obtained into the deformation behavior of steel sheets, as well as into how the internal structure of the material responds to mechanical loading at different thicknesses.
Abstract Blending hydrogen into existing natural gas infrastructure has many advantages, but there are unknown factors related to how safely natural gas pipeline infrastructure would operate when transporting hydrogen. Safety issues related to hydrogen blending include a loss of integrity in the pipeline system. It has long been known that gaseous hydrogen has a significant effect on the mechanical properties of pipeline steels, but the question remains as to how hydrogen susceptibility should be taken account when assessing their integrity. Tests performed on full-scale pipeline sections under complex loading conditions represent a reliable method for assessing the integrity of different pipeline sections. Our research presents tests carried out on pipeline sections exposed to hydrogen for different time lengths, on which full-scale tests were performed under complex loading conditions prior to hydrogen exposure. After the exposure times had elapsed, we performed burst tests on the pipeline sections and determined the safety factor values.
Abstract Survival is one of the essential characteristics of animals. In this review, we trace the historical development of themes related to embodied autonomous intelligence in the fields of artificial agents and robotics research. Previous work on robotics and neural models has focused on constructing models targeting specific cognitive functions, such as planning, image recognition, emotion, and language. In contrast, from the era of classical cybernetics to the present, there has also been a line of research that regards intelligence as an integrated, holistic property of the individual rather than as a collection of parts. In many of these studies, the survival of the individual is ultimately attributed to the physiological concept of homeostasis , which refers to the maintenance of appropriate internal bodily states. Unlike many robotic intelligences designed with specific goals, these robots are constructed as entities that, in essence, have no explicit external objectives beyond maintaining their internal states. In this paper, we highlight their potential in light of recent developments and discuss future directions and possible grand challenges.
Abstract Water contamination represents a critical challenge in helium cryogenic systems, presenting multifaceted operational risks for advanced industrial and scientific facilities. These water contaminants undergo complex phase transformations during system operations, crystallizing under extreme low-temperature conditions and posing significant threats to precision engineering infrastructure. Such crystallized particles can critically damage sensitive mechanical components, particularly turbines within coldbox assemblies, and accumulate within intricate heat exchanger networks, progressively compromising thermal transfer efficiency and overall system performance. At the National Synchrotron Radiation Research Center (NSRRC), we have developed an innovative moisture removal device capable of eliminating water contaminants both during offline maintenance and online system operation. Currently, four of these devices are deployed: one at the Taiwan Photon Source (TPS), two at the Taiwan Light Source, and one integrated with the purification system to enhance moisture contaminant removal capabilities. This paper will detail the device’s design and present comprehensive testing results.
Abstract An experimental study on the safety of a liquid hydrogen (LH 2 ) storage tank and transfer tube equipped with vacuum insulation has been carried out. A small-scale setup was used to simulate minute air leakage from the outside, caused by deterioration of the O-ring in the vacuum seal-off valve. This experiment investigated the increase in vacuum pressure when air was introduced into a vacuum chamber submerged in LH 2 , leading to the deposition of solid air components on the inner walls. A leak rate of approximately 10-3 Pa m 3 /s was introduced, revealing a slow pressure increasing to around 1 Pa by a long time constant. Additionally, an alternative method involving the leakage of carbon dioxide (CO 2 ) into a test chamber submerged in liquid nitrogen (LN 2 ) was examined to facilitate repeated experiments under safer conditions. Opportunities for LH 2 experiments are limited due to strict safety requirements. In contrast, the pressure increase observed in the LN 2 experiments was greater than that in the LH 2 experiments.
Abstract In previous current sharing simulation studies, we showed that a current sharing ratio can be defined, and that it is inversely proportional to the number of defects in the cable. We also gave a specific function for this, for a given set of boundary conditions, defect pattern, and thermal and electrical parameters. In this work, we explore the relationship between the current sharing ratio and different patterns of defects. A COMSOL simulation model, a four-tape stack model was used; a simple stack of tapes (a “carpet stack” or tape stack cable). The center two tapes had three pre-existing defects each, and each defect was 0.1 mm I n length with a critical current density of 0.1 J c . The defects in the center tapes were arranged either (i) at three equally spaced lengths along the stack length, but the same lengthwise position in both tapes (“column” pattern) or (ii) with the defects in the second tape positioned halfway between the lengthwise positions of those of the first tape (“zig-zag” pattern). The cable was modelled as being fully immersed in liquid helium. A stationary model was employed using an error tolerance of 1e-3 with a fine physics-controlled mesh. Other important parameters include an interstrand contact resistance (ICR) = 5400μΩ*cm 2 and an Interstrand thermal resistance (ITR) = 5.54 K*m 2 /W. Results show that the zig-zag defect pattern allows a higher current sharing ratio.
Abstract New superconducting magnets, based on Nb 3 Sn technology, have been developed for the HL-LHC project, the High-Luminosity upgrade of the LHC (Large Hadron Collider) at Interaction Points 1 and 5. These magnets require thorough testing in cryogenic conditions at 4.5 and 1.9 K before their installation into the LHC. Additionally, the HL-LHC includes high-current superconducting transmission lines (SC Links) for feeding the magnets of the Inner Triplets and Matching Sections at LHC Point 1 and Point 5, which also require cryogenic testing and validation before installation. The existing test benches built in the early 2000s to test the LHC magnets in CERN’S SM18 facility needed to be upgraded because the HL-LHC magnet apertures and internal line routings were incompatible. CERN has upgraded five test benches of the major LHC magnet test facility to perform the cryogenic powering tests and magnetic measurements of the HL-LHC magnets and SC Links. The upgrade included additional shuffling modules, anti-cryostats and new current leads. The paper details the cryogenic characteristics of the upgraded test benches and reports on the first operational results.
Abstract The SLAC National Accelerator Laboratory is home to LCLS-II, a world-class X-ray laser. The LCLS-II superconducting linac is supported by a cryogenic system comprising two identical subsystems with a cooling capacity of 4 kW at 2.0 K per cryoplant. Each cryoplant features a warm helium compressor station, a 4.5 K cold box, and a 5-stage 2 K cold compressor train. Installed and commissioned between 2018 and 2023, the cryogenic system has encountered several power outages since beginning of commissioning in 2023, presenting significant operational challenges. This paper highlights the most notable power outage incidents, their impact on the cryogenic infrastructure, and the measures undertaken to address these challenges. The lessons learned provide valuable insights into enhancing the resilience of complex cryogenic systems to power and other utility outages.
Abstract Power over Fiber (PoF) technology, which enables the transmission of electrical power via optical fibers, has gained significant traction across diverse applications, including telecommunications, aerospace, and high-voltage power distribution. Its unique advantages—such as intrinsic electrical isolation, immunity to electromagnetic interference, and excellent thermal insulation—make it particularly valuable in environments where conventional power delivery poses risks or limitations. A new application for PoF is its use in cryogenic environments, where the low thermal conductivity of optical fibers allows them to bridge extreme temperature gradients without significant heat transfer. This paper builds upon prior research exploring PoF systems operating under cryogenic conditions. This paper will present a study of system performance across a range of temperatures, capturing key operational trends and performance metrics as a function of temperature. Our results highlight critical insights into power conversion efficiency, thermal stability, and optical-to-electrical energy transfer characteristics at low temperatures. The findings are instrumental in guiding the future design and optimization of PoF systems for cryogenic and extreme environments, paving the way for more efficient, reliable, and high-power solutions in next-generation scientific and industrial applications.
Abstract Hydrogen liquefaction plants are a key component of liquid hydrogen supply chains. However, to meet future hydrogen demands for climate-friendly mobility, a significant scale-up is necessary. This study aims to provide a deeper understanding of hydrogen liquefaction plants by presenting process simulations of smaller- and large-scale plants using UniSim® Design. The process simulations accurately integrate the conversion of orthohydrogen to parahydrogen taking place continuously within the heat exchanger channels, along with the associated conversion heat. A techno-economic analysis evaluates the cost-effectiveness and energy efficiency of the processes. The results, which are validated against literature data, indicate that CAPEX and OPEX contribute equally to the overall liquefaction costs, with heat exchangers and compressors identified as the main cost drivers. A significant reduction in specific CAPEX and specific energy consumption is observed with increasing plant size, influenced by economy of scale and precooling technology. By integrating process simulation with techno-economic evaluation, this study provides valuable insights into the performance and specific costs of hydrogen liquefaction plants.
Abstract Cryocoolers in space instruments cool detectors and superconducting devices to cryogenic temperatures. Inside a cryocooler, a flexure spring ensures the cryocooler piston is axially free and radially restricted to prevent off-axis forces. Given that the flexure spring is mission-critical to the cryocooler operation yet prone to failure, its lifetime can determine the lifetime of the space mission. By improving the flexure spring design, space missions can be extended and present longer reliability. This study investigated the impact of various spring design parameters on a spiral flexure spring with spring arms in a characteristic spiral shape. These parameters include the number of arms, spring design, and thickness. Results show that the lowest maximum stress is observed at lower spring thickness values, moderate arm numbers, and teardrop sizes that vary for different arm numbers. Based on these results, an optimal design is proposed that maximizes flexure spring lifetime while operating at a resonant frequency to reduce the input power and increase lifetime. In this design, the design parameters are adjusted for optimal flexibility as a proof of concept, with additional designs inspired by kirigami proposed. In the latter design, a longer lifetime is demonstrated, extending to the lifespan of space missions that rely on cryocooler operation.
Abstract Thermal margins are critical to the development, the production, the test, and ultimately the performance of thermal subsystems. The subset of thermal subsystems that are cryogenic are even more reliant on thermal margins for success. Thermal uncertainty margins cover the inherent uncertainty, due to both design and analysis limitations, of predicting performance in space. They are not equivalent to sensitivity analyses that focus on the impact on performance of individual design and analysis parameters and assumptions. Thermal margins cover all the areas of uncertainty in the design. These include areas that are nearly impossible to eliminate uncertainty such as: thermal interstitial joints (workmanship influenced), orbit environments (transient), surface properties (vary with individual surfaces), thermophysical properties (vary with individual material lots), MLI (empirical ranges), etc. These areas often have empirically derived ranges. At BAE Systems (formerly Ball Aerospace) cryogenic margin is based on the MIL-STD philosophy, which this paper will cover in more detail. It is critical to not only establish, but track margins, throughout a program, from pre-proposal to on-orbit. Examples will be provided that show the tracking of margin on several actual BAE programs.
Abstract Monitoring the state of polarisation of the skylight is valuable for polarisation-based embodied navigation systems, meteorology, atmospheric measurements, insects’ behaviour, mobile robotics and remote sensing. This study presents the design and implementation of a dual-camera optical system capable of acquiring and processing polarized skylight images from a pair of cameras. The acquisition system integrates two complementary polarisation imaging strategies: Division of Time (DoT) and Division of Focal Plane (DoFP), allowing the real-time acquisition of high-res images and polarisation data. A complete hardware and software architecture was developed, including a Raspberry Pi-based control unit, a user-friendly graphical user interface (GUI), and dedicated acquisition workflows for each camera. Indoor experiments validate the system’s ability to capture and visualize key polarisation parameters such as Degree of Linear polarisation (DoLP) and Angle of polarisation (AoP). AoP pattern can be either globally or locally computed, which is very useful for image processing. Although challenges remain in integrating both devices within a single software environment, the results demonstrate the potential of this system to collect polarisation data. Our setup offers a promising tool for long-term data recording, supporting future developments in numerous scientific fields including embodied intelligence in robotics.
Abstract Traditional robotic systems often struggle in extreme, resource-limited environments, such as collapsed disaster zones, unstructured planetary surfaces, or ecological monitoring sites, ultimately limiting the usefulness of these robots for critical tasks where human intervention is impossible or dangerous. Their conventional design paradigm, heavily reliant on extensive sensor arrays, centralized computational units, and global planning algorithms, renders them bulky, energy-intensive, and inherently susceptible to degradation or failure under harsh, unpredictable conditions. Inspired by biological systems, an emerging paradigm in robotics emphasizes minimalist design principles, significantly reducing the reliance on extensive actuator and sensor arrays. This approach leverages the concept of morphological computation, where the robot’s physical structure and material properties intrinsically contribute to control and information processing, effectively “outsourcing” computational load from dedicated processors to the body’s mechanics. This enables adaptability in challenging media, from navigating viscous fluids to traversing unstable granular terrains, not through complex processing, but via the intelligent interplay of physical form, rhythmic control, and environmental interactions. Inspired by biological models such as flagellated microorganisms, flipper-based terrestrial animals, and amphibious species, this review explores embodiment-driven minimalist robots in extreme environments, highlighting how shape, compliance, and gait patterns contribute to efficient locomotion across various scales in these harsh environments. By emphasizing strategies like passive mechanics for inherent environmental adaptation, morphological tuning, and gait design, we demonstrate how minimalist philosophy, tightly integrated with physical dynamics, enables robust and energy-efficient navigation in fluid, granular, and hybrid terrains, positioning these robots as powerful models for studying and engineering intelligent behavior in physical systems.
Abstract The National Strategy for the Development of Bulgaria Culture (until 2029) in the field of cultural heritage identifies its preservation, socialization, and disclosure as a factor for sustainable development, identity, and cultural dialogue, with a sub-priority of introducing modern models for the study, preservation, presentation, and revitalization of immovable cultural heritage. Achieving the defined sub-priority requires the application of an integrated approach for better inter-institutional communication and coordination between all participants in the processes of preserving immovable cultural heritage. The principle of the integrated approach, in which immovable cultural heritage is considered in its physical and cultural context, is based on the interaction of two current paradigms in the field of technology – spatial geoinformation modeling and building information modeling in the field of immovable cultural heritage. As a result, two independent but interrelated models are realized – spatial geoinformation model and building information model. This publication examines the important aspects of geodetic support in the integration of these two models related to immovable cultural heritage. The current geodetic methods, technologies, and solutions are considered from the point of view of necessary, sufficient, implementing and integrating conditions for the integration of the two models in the scope of immovable cultural heritage, in accordance with the current geodetic approaches and applicable subordinate legislation in the technological field, especially the provisions and specifics of the Bulgarian Geodetic System 2005 introduced for the territory of the Republic of Bulgaria.
Abstract The aim of this paper is to study the current accelerator technology of luggage inspection system (LIS) in Malaysia. Typically, luggage inspection system is used to detect the objects inside the luggage by using the high energy photon produced by an accelerator such X-ray tube. Many types of commercial luggage inspection systems are available in the global market, basically that system comprised of the two side-images and integration of accelerator, detector, image analysis with Artificial Intelligence (AI) functionality. In this paper, the current accelerator technology of luggage inspection system which have been installed and operated in Malaysia by Royal Malaysian Customs Department (RMCD) will be described by using the validation examples.
Abstract Zirconium-based fuel claddings can absorb hydrogen during reactor operation under corrosive conditions, which can degrade their mechanical properties. Above the maximum hydrogen concentration limit of 400 ppm, as specified by fuel manufacturers, the cladding may become brittle. In long-term dry storage of spent nuclear fuel, the stability of absorbed hydrogen and its potential release are of particular importance, as released hydrogen may accumulate in confined gas volumes and represent a safety risk. This study investigates hydrogen desorption from zirconium fuel cladding materials at temperatures relevant to dry storage, focusing on room temperature, the regulatory limit of 410 °C, and an elevated temperature of 600 °C. E110-type zirconium alloy samples were hydrogen-charged, and hydrogen release was assessed using various methods. Mass measurements over 651 days at room temperature showed no change in hydrogen content. Vacuum heat treatments at 410 °C also did not result in significant hydrogen desorption, indicating that the current dry storage temperature limit can be applied safely. However, at 600 °C, significant hydrogen desorption was observed, with rates up to 100 ppm per hour. These findings contribute to refining the thermal safety limits for long-term nuclear waste storage.
Abstract Superconducting radio frequency (SRF) cavities used in modern particle accelerators require operation at 2 K with superfluid helium. For large-scale systems, the most practical approach is to use multi-stage cryogenic centrifugal compressors (cold compressors or CCs) to compress the sub-atmospheric helium returning from the load to positive pressure with a pressure ratio in the order of 40. The mass flow rate through the compressor train is typically controlled with a primary compressor, while the remaining compressors are coupled to the primary compressor through electronic speed ratios. Historically, the steady-state system parameters ( e.g. speed ratios) for a specific operating point were obtained empirically from extensive testing. Hence, the operating regime for these systems remained limited regardless of the actual 2 K load requirement. However, stable operation of the cold compressor system over a wide range of (mass flow) capacities to match the actual 2 K load is a major factor to meet the accelerator goals. In an event where the required 2 K load flow is lower than the design, overall cryogenic system operational cost savings from turning down the CC flow (a challenging task) can significantly outweigh the inefficiencies due to operation of the cold compressor system outside of its peak efficiency regime. Each g/s of reduction in CC mass flow can result in a 15 – 20 kW reduction of input power at the main 4 K refrigerator compressor system. A steady-state operating algorithm has been developed to improve 2 K system reliability and stability over a wide range of steady-state operational conditions. An in-house mean-line centrifugal compressor characterization model is used in conjunction with the developed algorithm to estimate the selection of electronic speed ratios for optimal stability under a given load (flow). Functionality and validity of the developed steady-state methodology is tested using the FRIB cold compressor system up to a 2:1 turn-down capacity range. Excellent agreement between the model predictions and the FRIB cold compressor system response is observed and presented.
Abstract The potential of geothermal resources is currently limited by existing drilling technology. To address this issue, the DeepU project is investigating the use of laser to drill deep wells (>4 km) to create a U-shaped closed-loop geothermal heat exchanger. This technology includes a high-power laser source and optics, a drill string, a drill head, a flushing system making use of cryogenic supercritical nitrogen and some ancillary systems required for successful rock penetration. Supercritical nitrogen is transferred down the borehole, then after isenthalpic expansion of the gas, it vitrifies the rock and flushes the rock debris to the surface. Mathematical model of nitrogen flow during the laser drilling was developed. Pneumatic transport modelling provided information on the required supply of supercritical nitrogen to provide the necessary cooling power and pneumatic transport of cuttings to the surface. Vacuum insulation was selected for the supercritical nitrogen transfer pipe. A custom coupling system was designed to ensure tightness, robustness and ease of assembly. Potential failure modes of the proposed system were identified and mitigation steps were proposed. The study demonstrates the feasibility of delivering supercritical nitrogen to a borehole several kilometres deep.
Abstract Purification of helium gas is vital for reliable operation of cryogenic systems operating at 4.5 K or below. Any extraneous matter will freeze, causing performance degradation or damage of cryogenic equipment. Removal of lowlevel (1-100 ppm v ) moisture contamination by freeze-out provides excellent control over a wide range of concentration. However, freeze-out processes require heat exchangers designed for contaminant solidification with minimal impact on flow distribution and heat exchange, and thorough understanding of frost formation on heat exchanger surfaces and the underlying heat and mass transfer. Frost formation in a cryogenic (300-80K) multi-pass tube-in-tube heat exchanger, integrated in a commercial helium purifier, is studied. A test bench incorporating the purifier and a novel low-level (5-100 ppm v of moisture) controlled contaminated gas generator is developed. The moisture freeze-out process in the test heat exchanger is studied under real-world and controlled conditions. Transient data relating heat exchanger performance, pressure drop, and deposited frost mass are collected. The effect of moisture concentration and flow imbalance on heat exchanger performance degradation and frost deposition are investigated. A 1D numerical model developed at FRIB was used to study the frost formation profile and capacity in the test heat exchanger, and its performance degradation.
