As the scale of urban rail transit (URT) networks expands, the study of URT resilience is essential for safe and efficient operations. This paper presents a comprehensive review of URT resilience and highlights potential trends and directions for future research. First, URT resilience is defined by three primary abilities: absorption, resistance, and recovery, and four properties: robustness, vulnerability, rapidity, and redundancy. Then, the metrics and assessment approaches for URT resilience were summarized. The metrics are divided into three categories: topology-based, characteristic-based, and performance-based, and the assessment methods are divided into four categories: topological, simulation, optimization, and data-driven. Comparisons of various metrics and assessment approaches revealed that the current research trend in URT resilience is increasingly favoring the integration of traditional methods, such as conventional complex network analysis and operations optimization theory, with new techniques like big data and intelligent computing technology, to accurately assess URT resilience. Finally, five potential trends and directions for future research were identified: analyzing resilience based on multisource data, optimizing train diagram in multiple scenarios, accurate response to passenger demand through new technologies, coupling and optimizing passenger and traffic flows, and optimal line design.
New types of aerial robots (NTARs) have found extensive applications in the military, civilian contexts, scientific research, disaster management, and various other domains. Compared with traditional aerial robots, NTARs exhibit a broader range of morphological diversity, locomotion capabilities, and enhanced operational capacities. Therefore, this study defines aerial robots with the four characteristics of morphability, biomimicry, multi-modal locomotion, and manipulator attachment as NTARs. Subsequently, this paper discusses the latest research progress in the materials and manufacturing technology, actuation technology, and perception and control technology of NTARs. Thereafter, the research status of NTAR systems is summarized, focusing on the frontier development and application cases of flapping-wing micro-air vehicles, perching aerial robots, amphibious robots, and operational aerial robots. Finally, the main challenges presented by NTARs in terms of energy, materials, and perception are analyzed, and the future development trends of NTARs are summarized in terms of size and endurance, mechatronics, and complex scenarios, providing a reference direction for the follow-up exploration of NTARs.
In this article, a single-board integrated millimeter-wave (mm-Wave) asymmetric full-digital beamforming (AFDBF) array is developed for beyond-fifth-generation (B5G) and sixth-generation (6G) communications. The proposed integrated array effectively addresses the challenge of arranging a large number of ports in a full-digital array by designing vertical connections in a three-dimensional space and successfully integrating full-digital transmitting (Tx) and receiving (Rx) arrays independently in a single board. Unlike the traditional symmetric array, the proposed asymmetric array is composed of an 8 × 8 Tx array arranged in a square shape and an 8 + 8 Rx array arranged in an L shape. The center-to-center distance between two adjacent elements is 0.54λ0 for both the Tx and Rx arrays, where λ0 is the free-space wavelength at 27 GHz. The proposed AFDBF array possesses a more compact structure and lower system hardware cost and power consumption compared with conventional brick-type full-digital arrays. In addition, the energy efficiency of the proposed AFDBF array outperforms that of a hybrid beamforming array. The measurement results indicate that the operating frequency band of the proposed array is 24.25–29.50 GHz. An eight-element linear array within the Tx array can achieve a scanning angle ranging from −47° to +47° in both the azimuth and the elevation planes, and the measured scanning range of each eight-element Rx array is –45° to +45°. The measured maximum effective isotropic radiated power (EIRP) of the eight-element Tx array is 43.2 dBm at 28.0 GHz (considering the saturation point). Furthermore, the measured error vector magnitude (EVM) is less than 3% when 64-quadrature amplitude modulation (QAM) waveforms are used.
The high-resolution and nondestructive co-reference measurement of the inner and outer three-dimensional (3D) surface profiles of laser fusion targets is difficult to achieve. In this study, we propose a laser differential confocal (LDC)–atomic force probe (AFP) method to measure the inner and outer 3D surface profiles of laser fusion targets at a high resolution. This method utilizes the LDC method to detect the deflection of the AFP and exploits the high spatial resolution of the AFP to enhance the spatial resolution of the outer profile measurement. Nondestructive and co-reference measurements of the inner profile of a target were achieved using the tomographic characteristics of the LDC method. Furthermore, by combining multiple repositionings of the target using a horizontal slewing shaft, the inner and outer 3D surface profiles of the target were obtained, along with a power spectrum assessment of the entire surface. The experimental results revealed that the respective axial and lateral resolutions of the outer profile measurement were 0.5 and 1.3 nm, while the respective axial and lateral resolutions of the inner profile measurement were 2.0 nm and approximately 400.0 nm. The repeatabilities of the root-mean-square deviation measurements for the outer and inner profiles of the target were 2.6 and 2.4 nm, respectively. We believe our study provides a promising method for the high-resolution and nondestructive co-reference measurement of the inner and outer 3D profiles of laser fusion targets.
With the escalating flow of information and digital communication, information security has become an increasingly important issue. Traditional cryptographic methods are being threatened by advancing progress in computing, while physical encryption methods are favored as a viable and compelling avenue. Metasurfaces, which are known for their extraordinary ability to manipulate optical parameters at the nanoscale, exhibit significant potential for the revolution of optical devices, making them a highly promising candidate for optical encryption applications. Here, a single-sized metasurface with four independent channels is proposed for conducting steganography and multi-key information encryption. More specifically, plaintext is transformed into a ciphertext image, which is encoded into a metasurface, while the decryption key is discretely integrated into another channel within the same metasurface. Two different keys for steganographic image unveiling are also encoded into the metasurface and can be retrieved with different channels and spatial positions. This distributed multi-key encryption approach can enhance security, while strategically distributing images across distinct spatial zones serves as an additional measure to reduce the risk of information leakage. This minimalist designed metasurface, with its advantages of high information density and robust security, holds promise across applications including portable encryption, high-camouflaged image display, and high-density optical storage.
The removal of microplastics (MPs) from water using oil has shown early promise; however, incorporation of this technique into a feasible in situ method has yet to be developed. Here, a simple yet effective method of MP capture from water using vegetable oil with bubbles is demonstrated to achieve high removal efficiencies of > 98%. Comparisons are made with other methods of agitation, and higher removal efficiencies are observed when bubbles are used. Due to the low agitation provided by the bubbles, the oil layer remains unbroken, meaning that no oil is released into the bulk water phase. In this way, secondary contamination is avoided—unlike membrane filtration, another effective removal method, in which polymer-based membranes can break down due to chemical backwashing and ageing. It is demonstrated that variation in MP size within the micrometer range (50–170 μm) has minor impact on the removal efficiency; however, 100% removal is achieved for larger, millimeter-sized MPs (500–5000 μm). Similarly, a high removal efficiency of greater than 99% is achieved in the capture of microfibers. Other factors such as oil volume and water salinity are also investigated and discussed. Based on these results, the proposed method can be introduced into multiple setting types as a passive and continuous method of MP capture.
The direct one-step separation of polymer-grade C2H4 from complex light hydrocarbon mixtures has high industrial significance but is very challenging. Herein, an ethylene-adsorption-weakening strategy is applied for precise regulation of the pore geometry of four tailor-made metal–organic frameworks (MOFs) with pillar-layered structures, dubbed TYUT-10/11/12/13. Based on its pore geometry design and functional group regulation, TYUT-12 exhibits exceptional selective adsorption selectivity toward C3H8, C3H6, C2H6, C2H2, and CO2 over C2H4; its C2H6/C2H4 adsorption selectivity reaches 4.56, surpassing the record value of 4.4 by Fe2(O2)(dobdc) (dobdc4− = 2,5-dioxido-1,4-benzenedicarboxylate). The weak π–π stacking binding affinity toward C2H4 in TYUT-12 is clearly demonstrated through a combination of neutron powder diffraction measurements and theoretical calculations. Breakthrough experiments demonstrate that C2H4 can be directly obtained from binary, ternary, quaternary, and six-component light hydrocarbon mixtures with over 99.95% purity.
The steel industry is considered an important basic sector of the national economy, and its high energy consumption and carbon emissions make it a major contributor to climate change, especially in China. The majority of crude steel in China is produced via the energy- and carbon-intensive blast furnace–basic oxygen furnace (BF–BOF) route, which greatly relies on coking coal. In recent years, China's steel sector has made significant progress in energy conservation and emission reduction, driven by decarbonization policies and regulations. However, due to the huge output of crude steel, the steel sector still produces 15% of the total national CO2 emissions. The direct reduced iron (DRI) plus scrap–electric arc furnace (EAF) process is currently considered a good alternative to the conventional route as a means of reducing CO2 emissions and the steel industry's reliance on iron ore and coking coal, since the gas-based DRI plus scrap–EAF route is expected to be more promising than the coal-based one. Unfortunately, almost no DRI is produced in China, seriously restricting the development of the EAF route. Here, we highlight the challenges and pathways of the future development of DRI, with a focus on China. In the short term, replacing natural gas with coke oven gas (COG) and byproduct gas from the integrated refining and chemical sector is a more economically feasible and cleaner way to develop a gas-based route in China. As the energy revolution proceeds, using fossil fuels in combination with carbon capture, utilization, and storage (CCUS) and hydrogen will be a good alternative due to the relatively low cost. In the long term, DRI is expected to be produced using 100% hydrogen from renewable energy. Both the development of deep processing technologies and the invention of a novel binder are required to prepare high-quality pellets for direct reduction (DR), and further research on the one-step gas-based process is necessary.
Arch bridges provide significant technical and economic benefits under suitable conditions. In particular, concrete-filled steel tubular (CFST) arch bridges and steel-reinforced concrete (SRC) arch bridges are two types of arch bridges that have gained great economic competitiveness and span growth potential due to advancements in construction technology, engineering materials, and construction equipment over the past 30 years. Under the leadership of the author, two record-breaking arch bridges—that is, the Pingnan Third Bridge (a CFST arch bridge), with a span of 560 m, and the Tian’e Longtan Bridge (an SRC arch bridge), with a span of 600 m—have been built in the past 5 years, embodying great technological breakthroughs in the construction of these two types of arch bridges. This paper takes these two arch bridges as examples to systematically summarize the latest technological innovations and practices in the construction of CFST arch bridges and SRC arch bridges in China. The technological innovations of CFST arch bridges include cable-stayed fastening-hanging cantilevered assembly methods, new in-tube concrete materials, in-tube concrete pouring techniques, a novel thrust abutment foundation for non-rocky terrain, and measures to reduce the quantity of temporary facilities. The technological innovations of SRC arch bridges involve arch skeleton stiffness selection, the development of encasing concrete materials, encasing concrete pouring, arch rib stress mitigation, and longitudinal reinforcement optimization. To conclude, future research focuses and development directions for these two types of arch bridges are proposed.
The rail transit in sulfate-rich areas faces the combined effects of stray current and salt corrosion; however, the sulfate ion transport and concrete degradation mechanisms under such conditions are still unclear. To address this issue, novel sulfate transport and mesoscale splitting tests were designed, with a focus on considering the differences between the interfacial transition zone (ITZ) and cement matrix. Under the influence of stray current, the ITZ played a pivotal role in regulating the transport and mechanical failure processes of sulfate attack, while the tortuous and blocking effects of aggregates almost disappeared. This phenomenon was termed the “stray current-induced ITZ effect”. The experimental data revealed that the difference in sulfate ion transport attributed to the ITZ ranged from 1.90 to 2.31 times, while the difference in splitting strength ranged from 1.56 to 1.64 times. Through the real-time synchronization of splitting experiments and microsecond-responsive particle image velocimetry (PIV) technology, the mechanical properties were exposed to the consequences of the stray current-induced ITZ effect. The number of splitting cracks in the concrete increased, rather than along the central axis, which was significantly different from the conditions without stray current and the ideal Brazilian disk test. Furthermore, a sulfate ion mass transfer model that incorporates reactivity and electrodiffusion was meticulously constructed. The embedded finite element calculation exhibited excellent agreement with the experimental results, indicating its reliability and accuracy. Additionally, the stress field was determined utilizing analytical methods, and the mechanism underlying crack propagation was successfully obtained. Compared to the cement matrix, a stray current led to more sulfates, more microstructure degradation, and greater increases in thickness and porosity in the ITZ, which was considered to be the essence of the stray current-induced ITZ effect.
Scientific and technological revolutions and industrial transformations have accelerated the rate of innovation in environmental engineering technologies. However, few researchers have evaluated the current status and future trends of technologies. This paper summarizes the current research status in eight major subfields of environmental engineering—water treatment, air pollution control, soil/solid waste management, environmental biotechnology, environmental engineering equipment, emerging contaminants, synergistic reduction in pollution and carbon emissions, environmental risk, and intelligent management—based on bibliometric analysis and future trends in greenization, low carbonization, and intelligentization. Disruptive technologies are further identified based on discontinuous transformation, and ten such technologies are proposed, covering general and specific fields, technical links, and value sources. Additionally, the background and key innovations in disruptive technologies are elucidated in detail. This study not only provides a scientific basis for strategic decision-making, planning, and implementation in the environmental engineering field but also offers methodological guidance for the research and determination of breakthrough technologies in other areas.
Microwave absorption (MA) materials are essential for protecting against harmful electromagnetic radiation. In this study, highly efficient and ultrawide-band microwave-absorbing fabrics with superhydrophobic surface features were developed using a facile dip-coating method involving in situ graphene oxide (GO) reduction, deposition of TiO2 nanoparticles, and subsequent coating of a mixture of polydimethylsiloxane (PDMS) and octadecylamine (ODA) on polyester fabrics. Owing to the presence of hierarchically structured surfaces and low-surface-energy materials, the resultant reduced graphene oxide (rGO)/TiO2-ODA/PDMS-coated fabrics demonstrate superhydrophobicity with a water contact angle of 159° and sliding angle of 5°. Under the synergistic effects of conduction loss, interface polarization loss, and surface roughness topography, the optimized fabrics show excellent microwave absorbing performances with a minimum reflection loss (RLmin) of −47.4 dB and a maximum effective absorption bandwidth (EABmax) of 7.7 GHz at a small rGO loading of 6.9 wt%. In addition, the rGO/TiO2-ODA/PDMS coating was robust, and the coated fabrics could withstand repeated washing, soiling, long-term ultraviolet irradiation, and chemical attacks without losing their superhydrophobicity and MA properties. Moreover, the coating imparts self-healing properties to the fabrics. This study provides a promising and effective route for the development of robust and flexible materials with microwave-absorbing properties.
Tubular microfibers have recently attracted extensive interest for applications in tissue engineering. However, the fabrication of tubular fibers with intricate hierarchical structures remains a major challenge. Here, we present a novel one-step microfluidic spinning method to generate bio-inspired screwed conduits (BSCs). Based on the microfluidic rope-coiling effect, a viscous hydrogel precursor is first curved into a helix stream in the channel, and then consecutively packed as a hollow structured stream and gelated into an SC via ionic and covalent crosslinking. By taking advantage of the excellent fluid-controlling ability of microfluidics, various tubes with diverse structures are fabricated via simple control over fluid velocities and multiple microfluidic device designs. The perfusability and permeability results, as well as the encapsulation and culture of human umbilical vein endothelial cells (HUVECs), human pulmonary alveolar epithelial cells (HPAs), and myogenic cells (C2C12), demonstrate that these SCs have good perfusability and permeability and the ability to induce the formation of functional biostructures. These features support the uniqueness and potential applications of these BSCs as biomimetic blood vessels and bronchiole tissues in combination with tissue microstructures, with likely application possibilities in biomedical engineering.
In ophthalmology, the quality of fundus images is critical for accurate diagnosis, both in clinical practice and in artificial intelligence (AI)-assisted diagnostics. Despite the broad view provided by ultrawide-field (UWF) imaging, pseudocolor images may conceal critical lesions necessary for precise diagnosis. To address this, we introduce UWF-Net, a sophisticated image enhancement algorithm that takes disease characteristics into consideration. Using the Fudan University Ultra-wide-field Image (FDUWI) dataset, which includes 11 294 Optos pseudocolor and 2415 Zeiss true-color UWF images, each of which is rigorously annotated, UWF-Net combines global style modeling with feature-level lesion enhancement. Pathological consistency loss is also applied to maintain fundus feature integrity, significantly improving image quality. Quantitative and qualitative evaluations demonstrated that UWF-Net outperforms existing methods such as contrast limited adaptive histogram equalization (CLAHE) and structure and illumination constrained generative adversarial network (StillGAN), delivering superior retinal image quality, higher quality scores, and preserved feature details after enhancement. In disease classification tasks, images enhanced by UWF-Net showed notable improvements when processed with existing classification systems over those enhanced by StillGAN, demonstrating a 4.62% increase in sensitivity (SEN) and a 3.97% increase in accuracy (ACC). In a multicenter clinical setting, UWF-Net-enhanced images were preferred by ophthalmologic technicians and doctors, and yielded a significant reduction in diagnostic time ((13.17 ± 8.40) s for UWF-Net enhanced images vs (19.54 ± 12.40) s for original images) and an increase in diagnostic accuracy (87.71% for UWF-Net enhanced images vs 80.40% for original images). Our research verifies that UWF-Net markedly improves the quality of UWF imaging, facilitating better clinical outcomes and more reliable AI-assisted disease classification. The clinical integration of UWF-Net holds great promise for enhancing diagnostic processes and patient care in ophthalmology.
Nonalcoholic steatohepatitis (NASH) may soon become the leading cause of end-stage liver disease worldwide with limited treatment options. Liver fibrosis, which is driven by chronic inflammation and hepatic stellate cell (HSC) activation, critically determines morbidity and mortality in patients with NASH. Pyruvate kinase M2 (PKM2) is involved in immune activation and inflammatory liver diseases; however, its role and therapeutic potential in NASH-related fibrosis remain largely unexplored. Bioinformatics screening and analysis of human and murine NASH livers indicated that PKM2 was upregulated in nonparenchymal cells (NPCs), especially macrophages, in the livers of patients with fibrotic NASH. Macrophage-specific PKM2 knockout (PKM2FL/FLLysM-Cre) significantly ameliorated hepatic inflammation and fibrosis severity in three distinct NASH models induced by a methionine- and choline-deficient (MCD) diet, a high-fat high-cholesterol (HFHC) diet, and a western diet plus weekly carbon tetrachloride injection (WD/CCl4). Single-cell transcriptomic analysis indicated that deletion of PKM2 in macrophages reduced profibrotic Ly6Chigh macrophage infiltration. Mechanistically, PKM2-dependent glycolysis promoted NLR family pyrin domain containing 3 (NLRP3) activation in proinflammatory macrophages, which induced HSC activation and fibrogenesis. A pharmacological PKM2 agonist efficiently attenuated the profibrotic crosstalk between macrophages and HSCs in vitro and in vivo. Translationally, ablation of PKM2 in NPCs by cholesterol-conjugated heteroduplex oligonucleotides, representing a novel oligonucleotide drug that preferentially accumulates in the liver, dose-dependently reversed NASH-related fibrosis without causing observable hepatotoxicity. The present study highlights the pivotal role of macrophage PKM2 in advancing NASH fibrogenesis. Thus, therapeutic modulation of PKM2 in a macrophage-specific or liver-specific manner may serve as a novel strategy to combat NASH-related fibrosis.
Carboxyl ester lipase (CEL), a pivotal enzyme involved in lipid metabolism, is recurrently mutated in obese mice. Here, we aimed to elucidate the functional significance, molecular mechanism, and therapeutic potential of CEL in metabolic dysfunction-associated steatohepatitis (MASH). Hepatocyte-specific Cel knockout (CelΔHEP) and wildtype (WT) littermates were fed with choline-deficient high-fat diet (CD-HFD) for 16 weeks, or methionine- and choline-deficient diet (MCD) for three weeks to induce MASH. Liquid chromatography-mass spectrometry and co-immunoprecipitation were employed to identify the downstream targets of CEL. CD-HFD/MCD-fed WT mice received intravenous injections of CEL-adeno-associated viral, serotype 8 (AAV8) to induce specific overexpression of CEL in the liver. We observed a decrease in CEL protein levels in MASH induced by CD-HFD or MCD in mice. CelΔHEP mice fed with CD-HFD or MCD exhibited pronounced hepatic steatosis, inflammation, lipid peroxidation, and liver injury compared to WT littermates, accompanied by increased hepatic nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) activation. Consistently, Cel knockdown in mouse primary hepatocytes and AML12 cells aggravated lipid accumulation and inflammation, whereas CEL overexpression exerted the opposite effect. Mechanistically, CEL directly bound to fatty acid synthase (FASN), resulting in reduced FASN SUMOylation, which in turn promoted FASN degradation through the proteasome pathway. Furthermore, inhibition of FASN using small interfering RNA (siRNA) or TVB-3664 ameliorated hepatocyte lipid accumulation and inflammation induced by Cel knockdown in vivo and in vitro. Hepatocyte-specific CEL overexpression using AAV8-Cel significantly mitigated steatohepatitis in mice fed with CD-HFD or MCD. CEL protects against steatohepatitis development by directly interacting with FASN and suppressing its expression for de novo lipogenesis. CEL overexpression confers a therapeutic benefit in steatohepatitis.
In situ regeneration is a promising strategy for constructing tissue engineering heart valves (TEHVs). Currently, the decellularized heart valve (DHV) is extensively employed as a TEHV scaffold. Nevertheless, DHV exhibits limited blood compatibility and notable difficulties in endothelialization, resulting in thrombosis and graft failure. The red blood cell membrane (RBCM) exhibits excellent biocompatibility and prolonged circulation stability and is extensively applied in the camouflage of nanoparticles for drug delivery; however, there is no report on its application for large-scale modification of decellularized extracellular matrix (ECM). For the first time, we utilized a layer-by-layer assembling strategy to immobilize RBCM on the surface of DHV and construct an innovative TEHV scaffold. Our findings demonstrated that the scaffold significantly improved the hemocompatibility of DHV by effectively preventing plasma protein adsorption, activated platelet adhesion, and erythrocyte aggregation, and induced macrophage polarization toward the M2 phenotype in vitro. Moreover, RBCM modification significantly enhanced the mechanical properties and enzymatic stability of DHV. The rat models of subcutaneous embedding and abdominal aorta implantation showed that the scaffold regulated the polarization of macrophages into the anti-inflammatory and pro-modeling M2 phenotype and promoted endothelialization and ECM remodeling in the early stage without thrombosis and calcification. The novel TEHV exhibits excellent performance and can overcome the limitations of commonly used clinical prostheses.
Gravimetric resonant-inspired biosensors have attracted increasing attention in industrial and point-of-care applications, enabling label-free detection of biomarkers such as DNA and antibodies. Capacitive micromachined ultrasonic transducers (CMUTs) are promising tools for developing miniaturized high-performance biosensing complementary metal-oxide-silicon (CMOS) platforms. However, their operability is limited by inefficient functionalization, aggregation, crosstalk in the buffer, and the requirement for an external high-voltage (HV) power supply. In this study, we aimed to propose a CMUTs-based resonant biosensor integrated with a CMOS front-end interface coupled with ethylene-glycol alkanethiols to detect single-stranded DNA oligonucleotides with large specificity. The topography of the functionalized surface was characterized by energy-dispersive X-ray microanalysis. Improved selectivity for on-chip hybridization was demonstrated by comparing complementary and non-complementary single-stranded DNA oligonucleotides using fluorescence imaging technology. The sensor array was further characterized using a five-element lumped equivalent model. The 4 mm2 application-specific integrated circuit chip was designed and developed through 0.18 μm HV bipolar-CMOS-double diffused MOS (DMOS) technology (BCD) to generate on-chip 20 V HV boosting and to track feedback frequency under a standard 1.8 V supply, with a total power consumption of 3.8 mW in a continuous mode. The measured results indicated a detection sensitivity of 7.943 × 10−3 μmol∙ L−1∙Hz−1 over a concentration range of 1 to 100 μmol∙L−1. In conclusion, the label-free biosensing of DNA under dry conditions was successfully demonstrated using a microfabricated CMUT array with a 2 MHz frequency on CMOS electronics with an internal HV supplier. Moreover, ethylene-glycol alkanethiols successfully deposited self-assembled monolayers on aluminum electrodes, which has never been attempted thus far on CMUTs, to enhance the selectivity of bio-functionalization. The findings of this study indicate the possibility of full-on-chip DNA biosensing with CMUTs.
Quality management is a constant and significant concern in enterprises. Effective determination of correct solutions for comprehensive problems helps avoid increased backtesting costs. This study proposes an intelligent quality control method for manufacturing processes based on a human–cyber–physical (HCP) knowledge graph, which is a systematic method that encompasses the following elements: data management and classification based on HCP ternary data, HCP ontology construction, knowledge extraction for constructing an HCP knowledge graph, and comprehensive application of quality control based on HCP knowledge. The proposed method implements case retrieval, automatic analysis, and assisted decision making based on an HCP knowledge graph, enabling quality monitoring, inspection, diagnosis, and maintenance strategies for quality control. In practical applications, the proposed modular and hierarchical HCP ontology exhibits significant superiority in terms of shareability and reusability of the acquired knowledge. Moreover, the HCP knowledge graph deeply integrates the provided HCP data and effectively supports comprehensive decision making. The proposed method was implemented in cases involving an automotive production line and a gear manufacturing process, and the effectiveness of the method was verified by the application system deployed. Furthermore, the proposed method can be extended to other manufacturing process quality control tasks.
Effective engineering asset management (EAM) is critical to economic development and improving livability in society, but its complexity often impedes optimal asset functionalities. Digital twins (DTs) could revolutionize the EAM paradigm by bidirectionally linking the physical and digital worlds in real time. There is great industrial and academic interest in DTs for EAM. However, previous review studies have predominately focused on technical aspects using limited life-cycle perspectives, failing to holistically synthesize DTs for EAM from the managerial point of view. Based on a systematic literature review, we introduce an analytical framework for describing DTs for EAM, which encompasses three levels or categories: DT 1.0 for technical EAM, DT 2.0 for technical−human EAM, and DT 3.0 for technical−environmental EAM. Using this framework, we identify what is known, what is unknown, and future directions at each level. DT 1.0 addresses issues of asset quality, progress, and cost management, generating technical value. It lacks multi-objective self-adaptive EAM, however, and suffers from high application cost. It is imperative to enable closed-loop EAM in order to provide various functional services with affordable DT 1.0. DT 2.0 accommodates issues of human−machine symbiosis, safety, and flexibility management, generating managerial value beyond the technical performance improvement of engineering assets. However, DT 2.0 currently lacks the automation and security of human−machine interactions and the managerial value related to humans is not prominent enough in it. Future research needs to align technical and managerial value with highly automated and secure DT 2.0. DT 3.0 covers issues of participatory governance, organization management, sustainable development, and resilience enhancement, generating macro social value. Yet it suffers from organizational fragmentation and can only address limited social governance issues. Numerous research opportunities exist to coordinate different stakeholders. Similarly, future research opportunities exist to develop DT 3.0 in a more open and complex system.
Accurate origin–destination (OD) demand prediction is crucial for the efficient operation and management of urban rail transit (URT) systems, particularly during a pandemic. However, this task faces several limitations, including real-time availability, sparsity, and high-dimensionality issues, and the impact of the pandemic. Consequently, this study proposes a unified framework called the physics-guided adaptive graph spatial–temporal attention network (PAG-STAN) for metro OD demand prediction under pandemic conditions. Specifically, PAG-STAN introduces a real-time OD estimation module to estimate real-time complete OD demand matrices. Subsequently, a novel dynamic OD demand matrix compression module is proposed to generate dense real-time OD demand matrices. Thereafter, PAG-STAN leverages various heterogeneous data to learn the evolutionary trend of future OD ridership during the pandemic. Finally, a masked physics-guided loss function (MPG-loss function) incorporates the physical quantity information between the OD demand and inbound flow into the loss function to enhance model interpretability. PAG-STAN demonstrated favorable performance on two real-world metro OD demand datasets under the pandemic and conventional scenarios, highlighting its robustness and sensitivity for metro OD demand prediction. A series of ablation studies were conducted to verify the indispensability of each module in PAG-STAN.