Search Results (2,207)

Spaceborne neural processing units (NPUs) increasingly support real-time deep-learning inference, but their dense multiply-accumulate arrays are vulnerable to radiation-induced soft errors. Conventional radiation-hardening methods improve reliability through hardware redundancy, but they incur substantial area, performance and compiler-mapping overheads. This paper proposes tile-resilient algorithm-based fault tolerance (TR-ABFT), a software-scheduled, detection-oriented scheme for quantized NPU inference. TR-ABFT generates checksum information at tile granularity and maps checking tasks onto the original processing element (PE) array without changing the hardware topology. To make ABFT compatible with INT8 datapaths, we design two checksum-coding strategies: checksum decomposition and modulo-239 checksum coding. The modulo-239 scheme removes structural missed detections for two-bit flips with bit-position spacings in (1, 31), while preserving compatibility with signed INT8 inputs. Evaluations on ResNet, YOLOv8, and RT-DETR show that, on a $16\times 16$ array, TR-ABFT introduces only 6.37% to 24.61% additional computational overhead. By converting spatial redundancy into schedulable temporal redundancy, TR-ABFT preserves systolic-array regularity and provides a low-overhead reliability-enhancement mechanism for space-grade neural-network accelerators. Full article

On background cosmological scales, after subtraction of peculiar velocities and local bound-system motions, observed cosmological signals are redshifted rather than blueshifted. Yet, redshift alone does not distinguish the past lightcone of an expanding Universe from the future lightcone of a contracting one. In practice, the identification of the observed redshifted branch with the observational past is set primarily by electromagnetic radiation, whose retarded character is independently established in controlled physics, albeit over non-cosmological scales. From that perspective, the observed cosmological arrow is not separable from the causal/radiative prescription used to interpret the signals. This effective entanglement between the cosmological and the radiative arrows should nevertheless be distinguished from the notion of arrow used in the present work. Here instead, the relevant arrow is not thermodynamic but kinematic; it is defined by the symmetry or asymmetry of background lightcone observables under $\xi \leftrightarrow -\xi$, where $\xi \equiv ln(1+z)$ and z is the redshift—a criterion motivated directly by the time-reversal-symmetric special-relativistic longitudinal Doppler shift. Equivalently, the arrow considered here is the observed redshift/blueshift asymmetry of cosmological lightcone signals; retarded observations of an expanding FRW Universe are in the redshifted branch, whereas the opposite rapidity orientation would correspond to the blueshifted branch. This naturally suggests using rapidity-reversal symmetry as the redshift-space no-arrow condition when passing from special relativity (SR) to Friedmann–Robertson–Walker (FRW) cosmology, where the empty Milne Universe is a bridging borderline case. In fact, the viewpoint advocated here is that $\xi$-symmetry/asymmetry is practically more fundamental than t-symmetry/asymmetry simply because the former is more readily related to cosmological observables. It is shown here that generic non-empty FRW Universes possess an intrinsic $\xi$-asymmetry already at the background level, independently of entropy, coarse-graining, structure growth, or a Past Hypothesis. Full article

Air temperature measurements in atmospheric environmental monitoring are susceptible to radiation-induced bias under natural ventilation. This study develops a low-power naturally ventilated air temperature sensor and a correction method combining computational fluid dynamics (CFD) with machine learning. The sensor integrates a Pt100 thin-film platinum resistance probe (Heraeus Holding GmbH, Hanau, Germany), symmetric guide plates, and a dual aluminum-plate radiation shield to reduce radiative heating while improving airflow around the probe. A three-dimensional fluid–solid coupled heat-transfer model was established in ANSYS FLUENT 15.0 to optimize guide-plate spacing and inclination angle and quantify the effects of solar radiation, long-wave radiation, scattered radiation, air density, wind speed, solar elevation angle, and surface albedo on radiation error. CFD results identified a guide-plate spacing of 24 mm and an inclination angle of 45° as the preferred parameters. A multilayer perceptron (MLP) model trained with CFD-derived data was validated in field experiments using a Model 076B aspirated radiation shield (Met One Instruments, Inc., Grants Pass, OR, USA) as the reference. The model predicted radiation error with a root mean square error (RMSE) of 0.052 °C, a mean absolute error (MAE) of 0.042 °C, and a correlation coefficient of 0.92. The proposed sensor and correction method provide a low-power and easy-to-maintain approach for reducing radiation-induced bias in naturally ventilated air-temperature measurements, with potential applications in meteorological observation, air-quality monitoring, and agricultural microclimate assessment. Full article

Spacecraft are evolving toward larger scales and higher performance, enabling widespread application of sophisticated space structures such as space antennas and flexible solar arrays. Such structures may experience thermally induced vibration (TIV) due to the influence of sudden solar radiation heat flows when it enters and leaves the Earth’s shadow in orbit. This paper focuses on a space thin-walled tube structure as the test specimen, and conducts ground-based TIV experiments in a vacuum environment, comparing the results with numerical simulations. The numerical simulation results for various key parameters show good agreement with the experimental data. The relative errors of average temperature, quasi-static displacement, and vibration frequency are approximately 5%, while the relative error of vibration amplitude is around 10%. Leveraging the validated numerical model, this study further investigates the influence of gravity on the TIV of large space structures. The results indicate that the TIV response amplitude under orbital conditions is significantly larger than that obtained from ground-based experiments. Full article

Agrivoltaics is a promising technique, especially in view of the rapid population growth associated with the expansion of cultivated areas to satisfy the food demands of the population, and the increase in solar power plants, which require considerable space to supply the population with energy. Thus, the transition from agricultural to agrivoltaics systems and the transition from PV power plants to agrivoltaics systems can enable more efficient use of land for energy and agricultural production. However, the configuration of agrivoltaics systems, namely panel elevation, spacing between panels and between rows of panels, and panel size, defines the amount of material used. As a result, configuration can have a major impact on the environment. The aim of this study is to highlight the environmental impact from converting 1 ha of land used entirely for agricultural production to 1 ha of an agrivoltaic system, and from converting 1 ha of land used entirely for solar photovoltaic energy production to 1 ha of an agrivoltaic system through a life cycle assessment. Three different configurations of agrivoltaics systems are considered to assess the environmental potential of agrivoltaics configurations. This analysis is performed with SimaPro 9.4 software, using the ReCiPe Midpoint (H) method and the Eco-invent database. The study determined impacts on global warming, stratospheric ozone depletion, ionizing radiation, ozone formation, mineral resource scarcity, fossil resource scarcity, water consumption, and land use through the determination of the Land Equivalent Ratio (LER). The results show that impacts are highest for PV power plants, followed by the agrivoltaic system with the largest PV panels for all indicators, except for stratospheric ozone depletion, where impacts are highest for agrivoltaics and agricultural use systems. The results of the land evaluation showed that the agrivoltaic system Case 3 gave the best performance, with a Land Equivalent Ratio of 148.7%. Full article

In the context of subtropical cities, the slow-moving environment of HOD (Hospital-Oriented Development) faces the dual challenges of spatial fragmentation and an extreme hot and humid climate, which also restricts the outdoor space’s thermal environment performance. Taking the Macau Light Rapid Transit (LRT) Union Hospital Station as an example, this study constructs a “topology-climate” dual quantitative assessment framework that integrates space syntax and parametric universal thermal climate index (UTCI) simulation. In response to the current problems of mixed pedestrian and vehicular traffic and high-intensity heat radiation, a comprehensive intervention strategy combining three-dimensional stitching and spatial optimization is proposed. The results show that: (1) The implantation of three-dimensional corridors improved the spatial integration of the core area of the site by 67.0%, significantly optimizing network connectivity. (2) During the extreme high-temperature period of daytime (9:00–18:00) in summer and autumn, the intervention strategy precisely opened up a continuous low-heat-stress linear shade zone through the synergistic mechanism of building projection shadows, physical shading of connecting corridors, (landscape shading effect, original evaporation removed). (3) The study confirms that landscape-coupled shading layout is the most effective method, reducing potential pedestrian heat exposure across the entire area, while the three-dimensional connecting corridors precisely control the thermal environment of core walkways. Together, these two elements construct a “topology-climate” optimization framework, achieving a synergistic improvement in spatial accessibility and simulated thermal comfort performance under standard meteorological input and quantitatively verifying the optimization effectiveness of the tiered intervention scheme. This study provides a data-driven decision-making basis for optimizing potential walking thermal conditions for vulnerable groups and reshaping the space’s potential to improve microclimate via shading design of medical hub areas and also provides a scientific paradigm for TOD microclimate planning focused on shading-based thermal environment optimization. Full article

The detector array chips can be used to capture the transient space-time signal of the pulse radiation field. It is mainly composed of a photoelectric array detector and a readout circuit. However, the metal leads used to connect the detector and the readout circuit have long spacing. This can easily introduce additional delays, resulting in a decrease in the response performance of the chip, which cannot meet the goal of simultaneous transmission of ultra-fast detection signals. In recent years, the rapid development of three-dimensional interconnect technology has enabled the chip to achieve shorter interconnect spacing, smaller parasitic parameters and smaller delay time, thereby improving system response performance. The integrated detector array chips composed of three-dimensional interconnects has the advantages of fast signal interconnection transmission speed, high bandwidth, process compatibility and functional expansion compared with the traditional planar architecture. At the same time, there are some limitations and challenges. Therefore, this paper mainly reviews the evolution characteristics of the stacked architecture of the detector array chips, the process development and the nanosecond-level transmission integration challenges. This paper effectively incorporates the three into a unified framework. This provides a solution for the realization of integrated nanosecond detector array chips. Furthermore, it promotes the application and expansion of the chip in the pulse radiation field diagnosis technology. Full article

Head and neck lymphedema (HNL) is a common complication of head and neck cancer (HNC) treatment. Surgery and radiation, the backbones of HNC treatment, disrupt lymphatic networks through direct injury and fibrosis, leading to accumulation of lymphatic fluid in interstitial spaces. This causes swelling of external and internal structures, leading to decreased quality of life, cosmetic distress, social withdrawal, and functional deficits such as dysphagia, dysphonia, and reduced cervical mobility. In this narrative review, we provide a broad overview of the pathophysiology, assessment, and prevention of HNL. Key surgical factors include the extent of neck dissection, including specific levels removed. Radiation compounds surgical injury through lymphatic fibrosis in a dose-dependent manner. Emerging radiation de-escalation strategies may reduce HNL, though lymphedema is rarely studied as a trial endpoint. Moreover, assessment of HNL remains challenging due to the absence of a gold standard—patient-reported outcome measures, clinician-reported scales, and instrumental tests each capture distinct components of external and internal HNL. Currently, the cornerstone of HNL treatment is conservative management with complete decongestive therapy, which shows mixed efficacy and does not address internal HNL. Surgical options including lymphovenous anastomosis and vascularized lymph node transfer show early promise but remain limited to case reports and small series. Lymphatic imaging, particularly indocyanine green lymphography, represents a promising emerging modality for guiding personalized treatment planning, though application to the head and neck remains challenging. Ultimately, current management of HNL remains largely reactive, with a noticeable lack of preventative therapies. Future research may benefit from better defining surgical options, including HNL as an endpoint in radiation de-escalation trials, and validate emerging lymphatic imaging techniques in order to improve outcomes for HNC survivors. Full article

Slip ring–brush assemblies are widely used in satellite mechanisms to transmit power and signals across rotating interfaces. Under authentic space environments—vacuum, radiation-dominated thermal exchange, and long-duration operation—the coupled effects of mechanical contact dynamics, electrical conduction, intermittent separation, and arcing can accelerate wear and degrade reliability. This paper presents a surface-resolved multiphysics model for multi-track slip rings with staggered brushes. The ring surface is discretized on a circumferential–axial grid and endowed with correlated 3D roughness, enabling interference-based asperity contact. Brush normal dynamics (mass–spring–damper) convert runout and micro-vibration into normal-force ripple and separation events. Electrical conduction is modeled by a parallel admittance network combining pressure-dependent micro-contact conduction and an event-based arc channel activated by separation, opening velocity, and current density with stochastic ignition. A 2D thermal model with ADI integration accounts for Joule/friction heating, radiative cooling, and optional hub conduction. Wear evolves via an Archard-type mechanical term and an arc-energy-driven erosive term. A FAST–MACRO multiscale scheme (20 s FAST, 100 h MACRO with periodic recalibration) enables tractable long-horizon wear prediction while preserving arc statistics. Baseline simulations for a 28 V bus demonstrate rare but nonzero arc activity and predict spatially non-uniform wear at the micrometer scale after 100 h. Full article

EMAT technology for Non Destructive testing is an important method for materials testing in several industries. In EMAT tools, a key issue is the EMAT coils design and implementation. Depending on the type of inspection, the coil type should be selected, and then, its dimensions should be calculated. This paper describes a methodology to select, design and implement EMAT coils based on Lorentz Force for applications such as thickness measurement and crack detection. Unlike previous works that focus on a single coil topology, this study integrates coil selection, dimensional design, COMSOL-based radiation-pattern simulation and experimental validation within a single workflow. Four Lorentz-force coil designs are covered: PCB spiral (CSPCB), 3D-printed spiral (CS3D), PCB meander-line (CMPCB) and 3D-printed meander-line (CM3D). Key design parameters are explicitly addressed: number of turns N, outer and inner radii R and $r_0$, track width w and spacing s for spiral coils, and meander length and inter-trace distance for meander-line coils. Simulation verification is performed in COMSOL Multiphysics by evaluating the von Mises stress along a semicircular path around the coil to obtain the angular radiation pattern. Experimentally, polar radiation patterns are measured at 500 kHz, 1.9 MHz and 4 MHz on a steel specimen, matching the simulation frequencies, with maximum amplitudes of 32.2, 46.4, 47.9 and 10.6 mV for CSPCB, CS3D, CMPCB and CM3D, respectively, showing consistent agreement between simulated and measured lobe shape and directivity. This work also uses an analogy with radio frequency antennas to better understand the operation of coils through the concept of radiation patterns, in this case in solid materials such as steel. Full article

Amid rapid urbanization and the expansion of higher education campuses, the physical and psychological well-being of college students has garnered increasing scientific attention. Although outdoor activities are crucial for student health, participation rates are heavily constrained by outdoor thermal comfort (OTC). This study investigates the OTC of university students in Xi’an, China, utilizing the Universal Thermal Climate Index (UTCI) to assess thermal perceptions across four distinct open spaces and to propose localized bioclimatic design interventions. The results reveal four key findings: (1) The meteorological correlates of thermal sensation vary significantly by spatial typology; relative humidity (RH) and air temperature (Ta) dominate in sunken spaces (HB), whereas solar radiation (G), globe temperature (Tg), and wind velocity (Va) are the primary correlates in sports squares (CS) and activity squares (SH). (2) Thermal benchmarks exhibit remarkable spatial heterogeneity during summer. The Neutral UTCI (NUTCI) varied widely from 17.11 °C in hard-paved squares (SH) to 26.13 °C in shaded bridge areas (JG), with the corresponding neutral zones (NUTCIR) shifting accordingly. (3) Significant variations in thermal adaptation exist even within identical macro-climates, underscoring the necessity of microclimate-specific design. (4) Targeted bioclimatic strategies—including optimized vegetation deployment, shading structures, localized sprinkler systems, and permeable paving—are proposed. These findings provide actionable guidelines for urban planners and landscape architects to optimize campus environments, thereby encouraging outdoor engagement and enhancing student well-being. Full article

In coastal residential areas, the combined effects of high temperature, high humidity, and weak wind conditions during summer intensify outdoor heat exposure and reduce pedestrian thermal comfort. To investigate the influence mechanisms of tree height and spatial layout on pedestrian-level thermal comfort, this study selected a typical residential community in Chengyang District, Qingdao, as the research site. Based on field meteorological observations, an ENVI-met model was established and validated. Using the existing composite greening scenario as the baseline, three tree layout types (row, cluster, and free layouts) and four height scenarios (4 m, 6 m, 8 m, and 10 m) were configured to quantitatively compare variations in physiological equivalent temperature (PET) under different planting schemes. The results indicate that tree configuration significantly affects summer thermal comfort. Its regulatory mechanism is governed not only by air temperature reduction but also by shortwave radiation interception, longwave radiation accumulation, and shading continuity. Although low-to-medium height trees can reduce local air temperature through transpiration, their limited canopy height and shading continuity restrict their ability to effectively attenuate direct shortwave radiation at pedestrian level, and in some cases may even increase mean radiant temperature (Tmrt) and PET. In contrast, 10 m tall trees arranged in row and cluster layouts can form continuous shaded cores, with the 10 m cluster layout demonstrating the best overall performance by significantly reducing Tmrt and PET. The free layout, characterized by dispersed canopies and fragmented shading, provides relatively limited thermal comfort improvement. The findings suggest that residential greening optimization should strengthen the coordination between tree height, canopy structure, and activity spaces. Tall trees should be prioritized in children’s play areas, elderly resting areas, residential entrances, main pedestrian pathways, and west-facing sun-exposed zones, while integrating building shadows and road orientation to create a continuous yet not overly enclosed shading network, thereby enhancing summer thermal adaptability in residential areas. Full article

Vapor Pressure Deficit (VPD) is a critical determinant of atmospheric evaporative demand and plant water stress in tropical agricultural systems. This study applied a Gaussian Mixture Model (GMM) and K-Means clustering to 36,528 hourly meteorological observations collected from Eastern Thailand between August 2021 and September 2025, with the objective of identifying distinct atmospheric moisture regimes relevant to precision irrigation management in durian cultivation. Two input configurations were evaluated: a multivariate feature space comprising air temperature, relative humidity, wind speed, solar radiation, and VPD; and a univariate input consisting of VPD alone. Model selection for GMM was guided by the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC), while K-Means performance was assessed using the Elbow method, Silhouette Coefficient, Calinski–Harabasz Index, and Davies–Bouldin Index. For the multivariate input, GMM identified K = 7 as the optimal number of clusters, supported by the largest single-step reduction in both AIC and BIC at this transition point. For the univariate VPD input, K = 5 was selected as the most parsimonious and agriculturally interpretable solution. The seven clusters derived from the multivariate GMM were organized into four atmospheric moisture regimes, such as very low, moderate, high, and very high evaporative demand, capturing the full spectrum of diurnal and seasonal VPD variability characteristic of Eastern Thailand. The results demonstrate that GMM-based probabilistic clustering applied to multivariate meteorological inputs provides a more comprehensive characterization of atmospheric moisture dynamics than univariate or geometric clustering approaches, offering a practical framework for tiered irrigation scheduling and drought stress early warning systems in tropical fruit cultivation. Full article

Establishing long-term human settlements in deep space presents significant challenges. Environmental conditions, such as extreme temperature fluctuations, micrometeorite impacts, seismic activity, and exposure to solar and cosmic radiation, pose obstacles to the design and operation of habitat systems. Prolonged mission duration and vast distances from Earth introduce further complications in the form of delayed communication and limited resources, making Earth independence through appropriate autonomous management systems especially desirable. Enabling the modeling and simulation of the consequences of disruptions and faults, and their propagation through the various habitat subsystems, is critically needed for the development of resilience-based design frameworks and methods for autonomous operation. While existing simulation tools can assist in modeling isolated aspects of damage, the integration of damage propagation and the capacity to enable detection and repair are rarely considered in a computational model. This paper introduces and demonstrates an architecture designed specifically to enable the modeling and integration of faults and damage, as well as their cascading effects. By combining physics-based and phenomenological models, our approach balances computational efficiency with model fidelity. After describing the modeling approach and corresponding architecture, we demonstrate its application within HabSim, a system-level space habitat model developed by the NASA-funded Resilient Extraterrestrial Habitat Institute (RETHi), as a simulation-based design aid suited to early-phase trade studies. Fire hazard propagation within a lunar habitat is used as an illustrative example of how the architecture supports modeling of disruption consequences, propagation, detection, and repair, and of how HabSim can be leveraged for stochastic simulations to support resilience assessment. Resilience-focused studies that apply this architecture can quantify and compare design alternatives. Full article

We investigate the influence of dark matter halos surrounding supermassive black holes on the gravitational waves emitted by extreme mass ratio inspirals (EMRIs). Focusing on circular orbits, we model the orbital evolution by incorporating both gravitational-wave radiation reaction and dynamical friction induced by the dark matter distribution, including possible density spikes near the black hole. Using frequency-domain waveform analysis, we compute the phase evolution of gravitational waves and quantify the dephasing caused by different halo parameters, including slope, density, and mass ratio. We further explore the distinguishability of dark matter models with annihilation, non-annihilation, and p-wave velocity dependence, as well as the potential to differentiate between astrophysical and primordial black holes. Our results show that even small variations in the dark matter properties lead to observable phase differences over a four-year EMRI evolution, making space-based detectors such as LISA sensitive probes of central dark matter distributions. Finally, we employ the Fisher matrix formalism to estimate the precision with which key parameters, such as halo slope and density, can be constrained, demonstrating that EMRI observations provide a promising avenue to probe both the nature of dark matter and the formation history of supermassive black holes. Full article