Search Results (520)

Addressing the urgent need for lightweight and reusable energy-absorbing materials in aviation impact resistance, this study introduces an innovative multi-directional braided metamaterial design enabled by 4D printing technology. This approach overcomes the dual challenges of intricate manufacturing processes and the limited functionality inherent to traditional textile preforms. Six distinct braided structural units (types 1–6) were devised based on periodic trigonometric functions (Y = A sin(12πX)), and integrated with shape memory polylactic acid (SMP-PLA), thereby achieving a synergistic combination of topological architecture and adaptive response characteristics. Compression tests reveal that reducing strip density to 50–25% (as in types 1–3) markedly enhances energy absorption performance, achieving a maximum specific energy absorption of 3.3 J/g. Three-point bending tests further demonstrate that the yarn amplitude parameter A is inversely correlated with load-bearing capacity; for instance, the type 1 structure (A = 3) withstands a maximum load stress of 8 MPa, representing a 100% increase compared to the type 2 structure (A = 4.5). A multi-branch viscoelastic constitutive model elucidates the temperature-dependent stress relaxation behavior during the glass–rubber phase transition and clarifies the relaxation time conversion mechanism governed by the Williams–Landel–Ferry (WLF) and Arrhenius equations. Experimental results further confirm the shape memory effect, with the type 3 structure fully recovering its original shape within 3 s under thermal stimulation at 80 °C, thus addressing the non-reusability issue of conventional energy-absorbing structures. This work establishes a new paradigm for the design of impact-resistant aviation components, particularly in the context of anti-collision structures and reusable energy absorption systems for eVTOL aircraft. Future research should further investigate the regulation of multi-stimulus response behaviors and microstructural optimization to advance the engineering application of smart textile metamaterials in aviation protection systems. Full article

Indoor radon constitutes a public health issue in various regions across the United States as the second leading cause of lung cancer following tobacco smoke. The U.S. Environmental Protection Agency advises radon mitigation interventions for residential buildings with indoor radon concentrations exceeding the threshold level of 4 pCi/L. Despite considerable research assessing the technical effectiveness of radon mitigation systems, there remains a gap in understanding their broader influence on occupant behavior and preferences in residential design. This study aims to investigate the impact of residing in radon-mitigated homes within the Commonwealth of Kentucky—an area known for elevated radon concentrations—on occupants’ preferences regarding healthy home design attributes. The objectives of this research are twofold: firstly to determine if living in radon-mitigated homes enhances occupant awareness and consequently influences their preferences toward health-related home attributes and secondly to quantitatively evaluate and compare the relative significance homeowners assign to health-related attributes such as indoor air quality, thermal comfort, and water quality relative to conventional attributes including home size, architectural style, and neighborhood quality. The overarching purpose is to explore the potential role radon mitigation initiatives may play in motivating occupants towards healthier home construction and renovation practices. Using choice-based conjoint (CBC) analysis, this paper compares preferences reported by homeowners from radon-mitigated homes against those from non-mitigated homes. While the findings suggest a relationship between radon mitigation and increased preference for indoor air quality, the cross-sectional design limits causal interpretation, and the possibility of reverse causation—where health-conscious individuals are more likely to seek mitigation—must be considered. The results provide novel insights into how radon mitigation efforts might effectively influence occupant priorities towards integrating healthier design elements in residential environments. Full article

Recent progress in geospatial foundation models (GFMs) has demonstrated strong generalization capabilities for remote sensing downstream tasks. However, existing GFMs still struggle with fine-grained cropland classification due to ambiguous field boundaries, insufficient and low-efficient temporal modeling, and limited cross-regional adaptability. In this paper, we propose CropSTS, a remote sensing foundation model designed with a decoupled temporal–spatial attention architecture, specifically tailored for the temporal dynamics of cropland remote sensing data. To efficiently pre-train the model under limited labeled data, we employ a hybrid framework combining joint-embedding predictive architecture with knowledge distillation from web-scale foundation models. Despite being trained on a small dataset and using a compact model, CropSTS achieves state-of-the-art performance on the PASTIS-R benchmark in terms of mIoU and F1-score. Our results validate that structural optimization for temporal encoding and cross-modal knowledge transfer constitute effective strategies for advancing GFM design in agricultural remote sensing. Full article

Phase noise constitutes a pivotal performance parameter in microwave systems, and the evolution of microwave signal sources presents new demands on phase noise analyzers (PNAs) regarding sensitivity and bandwidth. Traditional electronics-based PNAs encounter significant limitations in meeting these advanced requirements. This paper provides an overview of recent progress in photonics-based microwave PNA research. Microwave photonic (MWP) PNAs are categorized into two main types: phase-detection-based and frequency-discrimination-based architectures. MWP phase-detection-based PNAs utilize ultra-short-pulse lasers or optical–electrical oscillators as reference sources to achieve superior sensitivity. On the other hand, MWP frequency-discrimination-based PNAs are further subdivided into photonic-substitution-type PNA and MWP quadrature-frequency-discrimination-based PNA. These systems leverage innovative MWP technologies to enhance overall performance, offering broader bandwidth and higher sensitivity compared to conventional approaches. Finally, the paper addresses the current challenges faced in phase noise measurement technologies and suggests potential future research directions aimed at improving measurement capabilities. Full article

This study addresses a critical deficiency in real estate management by examining how contractual arrangements between property owners and facility managers (FMs) can mitigate reputational damage arising from third-party liability incidents. While Spanish regulations impose comprehensive conservation and maintenance duties on property owners, current contractual frameworks inadequately protect owners from reputational risks when damages occur due to FMs’ negligence or operational failures. This conceptual study employs a systematic analysis of 16 Spanish regulations governing real estate conservation and maintenance duties, complemented by an examination of the statutory contract law and a Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis to evaluate the proposed solutions. The analysis reveals four distinct liability attribution blocks, ranging from quasi-objective owner liability to full objective installation holder liability. Current service contracts between owners and FMs provide insufficient reputational protection, as civil liability remains with the property owners regardless of the FMs’ performance. This study identifies specific contractual mechanisms—combining statutory work contracts with representative mandates and installation ownership transfers—that effectively redirect tort liability from owners to FMs. While this study focuses on Spanish regulatory frameworks as a methodologically necessary foundation for theoretical development, the conceptual framework provides transferable mechanisms for adaptation to other civil law jurisdictions. This study constitutes the first comprehensive analysis bridging legal architecture and facility management to propose novel liability transfer mechanisms within established frameworks. Full article

Superoxide dismutases (SODs) maintain redox homeostasis through the catalytic dismutation of superoxide anions, thereby affording protection to organisms against oxidative damage. The SOD family, encompassing Cu/Zn-SOD, Mn-SOD, Fe-SOD, and Ni-SOD, exhibits structural diversity and constitutes a multilevel antioxidant defense system with discrete subcellular localizations. Beyond their antioxidant functions, SODs also function as immunomodulatory proteins, regulating the maturation, proliferation, and differentiation of immune cells. They further fulfill a crucial role in host responses to parasitic infections. The current review synthesizes and critically evaluates extant research to comprehensively delineate the molecular architecture of SODs, their intricate post-translational modification (PTM) networks, and their dual regulatory mechanisms at the interface of immunomodulation and pathological processes. This review establishes a critical framework for elucidating the biological significance of redox homeostasis maintenance. Full article

In the 19th century, the British archaeologist Sir Alexander Cunningham identified the remains of an unidentified Buddhist monastery at Jamāl Gaṛhī, an ancient site located approximately 13 km from present-day Mardān, Pakistan. Subsequent excavations by the Archaeological Survey of India between 1920 and 1921 unearthed a schist inscription dated to the year “359”. Heinrich Lüders, the renowned German Indologist and epigraphist, attributed this inscription to the Dharmaguptaka sect/school. Despite this early attribution, the Monastery’s precise sectarian characteristics have remained largely unexplored in later scholarship. This article reevaluates the site’s sectarian identity by employing a “ground-to-text” methodology that integrates archaeological evidence with textual analysis, with a particular focus on the Chinese translation of the Dharmaguptaka Vinaya. Through this comparative framework, this study seeks to elucidate the religious ideas reflected in the site’s material culture and their relationship with Dharmaguptaka disciplinary thought. The analysis encompasses the architectural remnants of the stūpa excavated by Cunningham and the “Fasting Buddha” statuary, now preserved in the National Museum of Pakistan, the British Museum, and other sites, situating these artifacts within the distinctive visual and contemplative traditions linked to the Dharmaguptaka Vinaya. By integrating architectural, sculptural, textual, and epigraphic materials, this article provides a nuanced understanding of sectarian developments at Jamāl Gaṛhī and argues that an explicit emphasis on the ‘Middle Way’ ideology constituted a defining feature of the Dharmaguptaka tradition during this period. Full article

Visual Place Recognition (VPR) constitutes a pivotal task in the domains of computer vision and robotics. Prevailing VPR methods predominantly employ RGB-based features for query image retrieval and correspondence establishment. Nevertheless, such unimodal visual representations exhibit inherent susceptibility to environmental variations, inevitably degrading method precision. To address this problem, we propose a robust VPR framework integrating RGB and depth modalities. The architecture employs a coarse-to-fine paradigm, where global retrieval of top-N candidate images is performed using fused multimodal features, followed by a geometric verification of these candidates leveraging depth information. A Discrete Wavelet Transform Fusion (DWTF) module is proposed to generate robust multimodal global descriptors by effectively combining RGB and depth data using discrete wavelet transform. Furthermore, we introduce a Spiking Neuron Graph Matching (SNGM) module, which extracts geometric structure and spatial distance from depth data and employs graph matching for accurate depth feature correspondence. Extensive experiments on several VPR benchmarks demonstrate that our method achieves state-of-the-art performance while maintaining the best accuracy–efficiency trade-off. Full article

Scientific evaluation of architectural heritage value constitutes a crucial foundation for advancing effective conservation practices and guiding policy development. Fujian Tubao, a distinctive form of defensive vernacular architecture found in southeastern China, integrates military defense, residential functions, and clan-based social organization into a unified spatial structure, making it an important component of China’s regional cultural heritage. In response to current challenges of inadequate preservation and progressive loss of heritage value associated with Fujian Tubao, there is an urgent need to establish a systematic evaluation framework to support and inform conservation efforts. This study centered on Fujian Tubao and proposed a comprehensive value assessment system that could innovatively integrate Grounded Theory with the Analytic Hierarchy Process (AHP). The Grounded Theory was first adopted to extract value dimensions of architectural heritage and their underlying connotations, thereby forming a value cognition system. Subsequently, the AHP was applied to assign quantitative weights and establish the priority order of each dimension, ultimately constructing a value evaluation system that could identify core objects for heritage conservation and clarify the hierarchy of their relative importance. This study achieved methodological integration in both the value extraction and evaluation stages, overcoming limitations of a single-method approach in dimension identification and weight assignment. The framework ensures logical consistency in value structuring and enhances the scientific validity of results. This study formulated a standardized and replicable evaluation framework tailored to the heritage value of Fujian Tubao. It also provides theoretical support for future conservation planning and offers a methodological reference for value assessment across diverse categories of architectural heritage. Full article

Considering that piston internal combustion engines will remain essential converters of chemical energy into mechanical energy for an extended period, providing optimal diagnostic tools for their operation is imperative. Mechanical vibrations generated during machine operation constitute one of the most valuable sources of information about their technical condition. Their primary advantage lies in conveying diagnostic data with minimal time delay. This article presents a novel approach to vibroacoustic diagnostics of the combustion process in internal combustion piston engines. It leverages vibration signals carrying information about the pressure in the engine cylinder during fuel–air mixture combustion. In the proposed method, cylinder pressure information is reconstructed from vibration signals recorded on the cylinder head of the internal combustion engine. This method of signal-to-signal processing uses deep artificial neural network (ANN) models for signal reconstruction, providing an extensive exploration of the abilities of the presented models in the reconstruction of the pressure measurements. Furthermore, a novel two-network model, utilizing a U-net architecture with a dedicated smoothing network (SmN), allows for producing signals with minimal noise and outperforms other commonly used signal-to-signal architectures explored in this paper. To test the proposed methods, the study was limited to a single-cylinder engine, which presents certain constraints. However, this initial approach may serve as an inspiration for researchers to extend its application to multi-cylinder engines. Full article

The “hand-waving sacrifice” is a large-scale sacrificial ceremony with more than 2000 years of history. It was passed down from ancient times by the Tujia ethnic group living in the Wuling Corridor of China, and it integrates religion, sacrifice, dance, drama, and other cultural forms. It primarily consists of two parts: ritual content (inviting gods, offering sacrifices to gods, dancing a hand-waving dance, etc.) and the architectural space that hosts the ritual (hand-waving hall), which together constitute Tujia’s most sacred ritual space and the most representative art and culture symbol. Nonetheless, in existing studies, the hand-waving sacrifice ritual, hand-waving hall architectural space, and hand-waving dance art are often separated as independent research objects, and little attention is paid to the coupling mechanism of the mutual construction of space and ritual in the process of historical development. Moreover, with the acceleration of modernization, the current survival context of the hand-waving sacrifice has undergone drastic changes. On the one hand, the intangible cultural heritage protection policy and the wave of tourism development have pushed it into the public eye and the cultural consumption system. On the other hand, the changes in the social structure of traditional villages have led to the dissolution of the sacredness of ritual space. Therefore, using the interaction of “space-ritual” as a prompt, this research first uses GIS technology to visualize the spatial geographical distribution characteristics and diachronic evolution process of hand-waving halls in six historical periods and then specifically analyzes the sacred construction of hand-waving hall architecture for the hand-waving sacrifice ritual space throughout history, as well as the changing mechanism of the continuous secularization of the hand-waving sacrifice space in contemporary society. Overall, this study reveals a unique path for non-literate ethnic groups to achieve the intergenerational transmission of cultural memory through the collusion of material symbols and physical art practices, as well as the possibility of embedding the hand-waving sacrifice ritual into contemporary spatial practice through symbolic translation and functional extension in the context of social function inheritance and variation. Finally, this study has specific inspirational and reference value for exploring how the traditional culture and art of ethnic minorities can maintain resilience against the tide of modernization. Full article

Hydrogen-powered aircraft constitute a transformative innovation in aviation, motivated by the imperative for sustainable and environmentally friendly transportation solutions. This paper aims to concentrate on the design of hydrogen powertrains employing a system approach to propose representative design models for distribution and propulsion systems. Initially, the requirements for powertrain design are formalized, and a use-case-driven analysis is conducted to determine the functional and physical architectures. Subsequently, for each component pertinent to preliminary design, an analytical model is proposed for multidisciplinary analysis and optimization for powertrain sizing. A double-wall pipe model, incorporating foam and vacuum multi-layer insulation, was developed. The internal and outer pipes sizing were performed in accordance with standards for hydrogen piping design. Valves sizing is also considered in the present study, following current standards and using data available in the literature. Furthermore, models for booster pumps to compensate pressure drop and high-pressure pumps to elevate pressure at the combustion chamber entrance are proposed. Heat exchanger and evaporator models are also included and connected to a burning hydrogen engine in the sizing process. An optimal liner pipe diameter was identified, which minimizes distribution systems weight. We also expect a reduction in engine length and weight while maintaining equivalent thrust. Full article

Drying constitutes an essential step in aerogel fabrication, where the drying method directly determines the pore structure and consequently influences the material’s functionality. This study employed various drying techniques to prepare balsa-wood-derived aerogels, systematically investigating their effects on microstructure, density, and performance characteristics. The results demonstrate that different drying methods regulate aerogels through distinct pore structure modifications. Supercritical CO₂ drying optimally preserves the native wood microstructure, yielding aerogels with superior thermal insulation performance. Freeze-drying induces the formation of ice crystals, which reconstructs the microstructure, resulting in aerogels with minimal density, significantly enhanced permeability, and exceptional cyclic water absorption capacity. Vacuum drying, oven drying, and natural drying all lead to significant deformation of the aerogel pore structure. Among them, oven drying increases the pore quantity of aerogels through volumetric contraction, thereby achieving the highest specific surface area. However, aerogels prepared by air drying have the highest density and the poorest thermal insulation performance. This study demonstrates that precise control of liquid surface tension during drying can effectively regulate both the pore architecture and functional performance of wood-derived aerogels. The findings offer fundamental insights into tailoring aerogel properties through optimized drying processes, providing valuable guidance for material design and application development. Full article

The Guyang Cave contains an extensive collection of late Northern Wei (late fifth to early sixth century) statue and stele combinations. While existing scholarship has recognized the exceptional nature of these statue–stele pairings, their systematic stylistic classification and contextual interpretation have yet to receive sustained scholarly attention. This investigation analyzes ten paradigmatic cases, organized into three distinct stylistic groups. The discussion subsequently focuses on four particularly representative examples that epitomize divergent approaches to stele implementation. These stylistic differentiations emerge as direct responses to specific spatial contingencies within the cave’s architecture. Instead of being merely decorative, these innovative configurations served as ritual instruments, amplifying patrons’ devotional objectives within the cave’s competitive environment. Ultimately, this study contributes to the theoretical discourse on “ritual art” by revealing how spatial negotiations between patrons manifested as a dynamic ritual process—one that both informed and was sustained by artistic creation in the Guyang Cave. More broadly, in the late Northern Wei period, artistic expression and ritual practice emerged as mutually constitutive elements in the dynamic formation of religious and cultural traditions. Full article

State evaluation of relay protection equipment constitutes a crucial component in ensuring the stable, secure, and symmetric operation of power systems. Current methodologies predominantly encompass fuzzy-rule-based control systems and data-driven machine learning approaches. The former relies on manual experience for designing fuzzy rules and membership functions and exhibits limitations in high-dimensional data integration and analysis. The latter predominantly formulates state evaluation as a classification task, which demonstrates its ineffectiveness in identifying equipment at boundary states and faces challenges in model parameter selection. To address these limitations, this paper proposes a quantitative state evaluation method for relay protection equipment based on a two-stage artificial protozoa optimizer (two-stage APO) optimized improved Conformer (two-stage APO-IConf) model. First, we modify the Conformer architecture by replacing pre-layer normalization (Pre-LN) in residual networks with post-batch normalization (post-BN) and introducing dynamic weighting coefficients to adaptively regulate the connection strengths between the first and second feed-forward network layers, thereby enhancing the capability of the model to fit relay protection state evaluation data. Subsequently, an improved APO algorithm with two-stage optimization is developed, integrating good point set initialization and elitism preservation strategies to achieve dynamic equilibrium between global exploration and local exploitation in the Conformer hyperparameter space. Experimental validation using operational data from a substation demonstrates that the proposed model achieves a RMSE of 0.5064 and a MAE of 0.2893, representing error reductions of 33.6% and 35.0% compared to the baseline Conformer, and 9.1% and 15.2% error reductions over the improved Conformer, respectively. This methodology can provide a quantitative state evaluation and guidance for developing maintenance strategies for substations. Full article