Main Path Research Articles

Infrared-Visible Synthetic Data from Game Engine for Image Fusion Improvement

Limited by the shooting scenes and angles of fixed cameras, the existing datasets generally lack many detailed pedestrian models in diverse scenarios. Existing deep learning-based image fusion methods, for this reason, bring about overfitting or insufficient information of fusion results in varying degrees. To address this challenge, A new infrared-visible pedestrian synthetic dataset (GIVF) with a synthetic data tagger (GSDT) is constructed and an improved end-to-end image fusion network (FSGAN) is proposed to validate infrared and visible fusion. In the model, the method uses an auxiliary network to extract features that complement the cascade network of the main path, effectively improving the ability to extract pedestrian texture details. Experimental results show that FSGAN can be well applied to GIVF. By conducting extensive comparative experiments with eight state-of-the-art image fusion methods. FSGAN shows better performance than those comparison methods, especially in the two evaluation indexes visual information fidelity (VIF) and structural similarity measurement (SSIM). Besides, by comparing the quantitative analysis results of various methods, and evaluating the fusion results of real images in complex environments on other three datasets, we conclude that FSGAN can be better applied to GIVF datasets than other popular methods, and has outstanding performance in generalization.

Effects of Ramp-Induced Incident Shock Impingement Under Various Slope Angle Configurations in a Strut-Based/Cavity-Assisted Supersonic Combustor

ABSTRACT The present study conducts a numerical investigation into the effects of ramp-induced shock impingement with different opening angles on the global flow-field and combustion behaviors within a strut-based/cavity-assisted scramjet combustor. To reproduce the intricate physical phenomena and all inflow properties of the primary channel, two-dimensional Reynolds-averaged Navier–Stokes (RANS) equations integrated with the shear stress transport (SST) k − ω turbulence model is implemented. The current approach considers several slope angle configurations of the ramp since they generate various shock systems that differ in magnitudes and coherent structures, substantially affecting the combustion efficiencies and chemical species distributions. Results reveal that an optimal shock angle of the ramp in correspondence with the current operating conditions can be achieved at 20°, which increases the combustion efficiency by 11% at the end of the cavity trailing edge without provoking excessive loss of total mass-flux-weighted pressure recovery. However, further expanding the slope angle above the optimum will trigger the flow blockage mechanism which enlarges the recirculation region on both sides of the ramp, simultaneously initiate their local thickening processes and create shock train areas owing to intensive interactions with the turbulent boundary layers. These phenomena are known for decreasing the total pressure ratio, adversely affecting all performance metrics of interest and destabilizing the main channel flow path.

Intrinsic Low-Frequency Variability in the Upper-Layer Circulation of the East Sea (Sea of Japan)

Abstract The effects of external forcing variation on the intrinsic variability in the upper-layer circulation occurring within the East Sea (Sea of Japan) and its physical mechanism are analyzed using numerical experiments. In this study, the experiments were conducted with climatological annual/monthly mean forcings (constant/seasonal forcings). The intrinsic variability is mainly distributed in the meandering regions around the main current path with the comparatively large variability limited to the southern region. The reason of greater intrinsic variability mainly in the southern part of the East Sea than in the northern part is that more energy is required from external forcings to change the thicker upper layer formed in the northern part due to seasonal forcings (strong wind stress and surface heat flux). Although the experiments show slight differences, westward propagation of the Rossby wave appears in areas where the variability is large. The transport of the eddy momentum flux associated with the Rossby wave modulates the strength of the eastward jet and the north–south shift of its axis. Among the external forcings, the volume transport through the Korea/Tsushima Strait is the most important driver of intrinsic variability, and wind stress plays an important role in expanding and strengthening intrinsic variability. Significance Statement Intrinsic variability is an important factor in understanding the total variability in the upper-layer circulation in the East Sea (Sea of Japan). However, the physical mechanisms of intrinsic variability remain unclear. This study investigates the physical mechanisms of intrinsic variability occurring within the East Sea. The intrinsic variability occurs mainly around the main current path, especially the meandering current. Based on numerical experiments, the mechanism of the intrinsic variability is represented by the fluctuation in the strength of the eastward current or the north–south movement of its axis caused by the Rossby wave.

A Multi-Path Semantic Segmentation Network Based on Convolutional Attention Guidance

Due to the efficiency of self-attention mechanisms in encoding spatial information, Transformer-based models have recently taken a dominant position among semantic segmentation methods. However, Transformer-based models have the disadvantages of requiring a large amount of computation and lacking attention to detail, so we look back to the CNN model. In this paper, we propose a multi-path semantic segmentation network with convolutional attention guidance (dubbed MCAG). It has a multi-path architecture, and feature guidance from the main path is used in other paths, which forces the model to focus on the object’s boundaries and details. It also explores multi-scale convolutional features through spatial attention. Finally, it captures both local and global contexts in spatial and channel dimensions in an adaptive manner. Extensive experiments were conducted on popular benchmarks, and it was found that MCAG surpasses other SOTA methods by achieving 47.7%, 82.51% and 43.6% mIoU on ADE20K, Cityscapes and COCO-Stuff, respectively. Specifically, the experimental results prove that the proposed model has high segmentation precision for small objects, which demonstrates the effectiveness of convolutional attention mechanisms and multi-path strategies. The results show that the CNN model can achieve good segmentation effects with a lower amount of calculation.

Human extreme heat protective behaviours: the effects of physical risks, psychological perception, and public measures

Individual actions can mitigate the consequences of extreme heat. Therefore, understanding the mechanism of protective behaviours against extreme heat is critical. Although extreme heat protective behaviours have been widely mentioned, the roles of psychological risk perception and public restraint are poorly understood. In this study, we developed a physical-measure-psychosocial model (PMP) to reveal the intrinsic motivation for protective behaviours during extreme heat based on a nationwide survey in China (n = 1791). The results showed that (1) high levels of physical risk perception promote outdoor, indoor, and traffic protective behaviours. Psychological risk perception is positively associated with outdoor and indoor protective behaviours but is not significantly associated with traffic protective behaviour. (2) There are differences in the main paths from heat exposure to outdoor, indoor, and traffic protective behaviours. The indirect effect controlled by physical risk is the main path from exposure to outdoor and traffic protective behaviours, while the direct effect of heat exposure is the strongest pathway for indoor protective behaviour. (3) Enhanced facility conditions are linked to reduced physical risk and psychological risk perception. Subsidies have a significant effect on traffic protective behaviour, and warnings significantly affect outdoor protective behaviour. The direct effect of warning systems on outdoor protective behaviour is greater than the indirect effect mediated by psychological risk perception. (4) Multigroup analysis based on structural equation models revealed a certain degree of robustness among the different gender, age, education level, and income level groups. This study enables us to understand the underlying mechanisms of extreme heat behaviours and support policy-makers in effective mitigation practices.

Aligned and unaligned single-walled carbon nanotube bilayer films for uncooled infrared sensors

Semiconducting single-walled carbon nanotube (SWCNT) film fabrication using the dip-coating method has successfully produced a unique film with two layers of different morphologies, an upper layer of aligned SWCNT film and a lower layer of non-aligned SWCNT network film. In the upper layer, SWCNTs form SWCNT bundles of several SWCNT thicknesses, and the bundles form thin aligned SWCNT films of 2–7 nm in thickness with parallel and equally spaced bundles of SWCNTs. When a bolometer device with this bilayer film was fabricated on electrodes, the upper aligned SWCNT film was the main conductive path with a low resistivity of about 0.2 Ωcm around room temperature. The alignment film also achieved a high temperature coefficient of resistance (TCR) of more than −5%/K due to its thin thickness, which is hardly affected by the slight metallic SWCNT presence. These excellent properties of a high TCR and low resistance are advantageous for the development of innovative sensor elements.

Operational transfer path analysis based on neural network

Noise, vibration, and harshness (NVH) issues induced by vibrating source to receivers are sensitive concerns in the automotive industry, significantly determining the product quality. Transfer path analysis (TPA) serves as a crucial tool in addressing these concerns. However, classical and component-based TPA methods necessitate the measurement of all transfer functions associated with the NVH phenomenon, causing high experimental costs; moreover, operational TPA (OTPA) involves matrix inversion processes that may result in the loss of important information. In this study, a neural network-based OTPA (NOTPA) method is proposed that eliminates the need for a matrix inversion process and utilizes only operational measurement. To derive the physical meaning of transmissibility obtained from the trained neural network model, the learning algorithm for NOTPA was developed, and appropriate learning rules were applied to the model. In the general neural network model, training was performed using real-valued parameters. However, the phase of the signal is crucial information in the theoretical formulation of TPA; thus, a complex-valued propagation algorithm was established. Furthermore, an appropriate activation function was chosen to derive the actual transfer mechanism from the trained complex-valued parameters. To experimentally verify the NOTPA method, a testbed resembling automotive vehicle structure was constructed. Estimation of sound pressure and noise contribution analysis were conducted using the NOTPA method and compared with conventional TPA methods. The proposed method demonstrated higher accuracy compared to the conventional OTPA method and successfully identified the main transfer path compared to the classical TPA. Furthermore, by comparing the estimated sound pressure according to the architecture of the model, the consistency of the proposed model was verified.

Sediment records and multi-media transfer and fate of polycyclic aromatic hydrocarbons in Dianchi Lake over the past 100 years

This study analyzed the fate and transfer of PAHs through multiple media in Dianchi Lake and the sediment records of polycyclic aromatic hydrocarbons (PAHs) in sediments. The model simulation results showed the simulated concentrations to be in good agreement with the measured values. The concentration and total amount of PAHs were the highest in the sediment, which is an important sink for PAHs in lake systems. The main transport direction of the PAHs in the three phases was from the atmosphere to the water to the sediment. Advection and emission inputs were the primary input pathways for PAHs in the atmosphere, and advection output was the main removal path. The main input sources pathways for PAHs in sediments was the sedimentation of particulate matter in water, with diffusion and degradation being the primary methods of removal. Advection and atmospheric dry and wet deposition were the main sources of PAHs in water, with particulate deposition being the primary removal process. The range of PAHs was 336–3520 ng/g in sediments in Dianchi Lake, with an average of 1569 ng/g, peaking in 2012. Among the predicted future PAH concentrations in the sediments under the five shared socioeconomic pathways (SSPs), the lowest PAH concentration was found under SSP3 from 2025 to 2035, whereas the lowest PAH concentration was found under SSP4 from 2035 to 2050. In the sustainable path of SSP1, although the concentration of PAH pollutants showed an increasing trend in the short term, the increase in PAHs concentration in sediments slowed in the long run.

Equalizer Parameters’ Adjustment Based on an Oversampled Channel Model for OFDM Modulation Systems

A physical model of a wireless transmission channel in the time domain usually consists of the main propagation path and only a few reflections. The reasonable assumptions made about the channel model can improve its parameters’ estimation by a greedy OFDM (Orthogonal Frequency Division Multiplexing) equalizer. The equalizer works flawlessly if delays between propagation paths are in the sampling grid. Otherwise, the channel impulse response loses its compressible characteristic and the number of coefficients to find increases. It is possible to get back to the simple channel model by data oversampling. The paper describes how the above idea helps the OMP (Orthogonal Matching Pursuit) algorithm estimate channel coefficients. The authors analyze the oversampling algorithm on the one hand to assess the influence of filtering function and signal resolution on the quality of the channel impulse response reconstruction. On the other hand, the abilities of the OMP algorithm are analyzed to distinguish components of the oversampled signal. Based on these analyses, we proposed modifications to the compressible channel’s impulse response reconstruction algorithm to minimize the number of transmission errors. A distinction was made between the filters used in the OMP search and channel reconstruction stages before calculating equalizer coefficients. Additionally, the results of the search stage were considered as elements within the groups.

Bacteria Affect the Distribution of Soil-Dissolved Organic Matter on the Slope: A Long-Term Experiment in Black Soil Erosion

Soil erosion results in dissolved organic matter (DOM) loss and is one of the main paths of soil carbon loss. Bacteria affect the generation and transformation of DOM. However, the effect of bacteria on the composition and slope distribution of DOM has rarely been investigated under field conditions. Based on a long-term experiment of three gradients (3°, 5°, 8°) in a black soil erosion area of Northeast China, the content, composition, and source of DOM were studied. The results showed that the DOM of the 3° and 5° slope was enriched midslope, and the DOM of the 8° slope was enriched downslope. Parallel factor (PARAFAC) analysis indicated that the main substances in DOM were fulvic-like acid, humic-like acid, tryptophan-like protein, and soluble microbial metabolites. The upslope and downslope soils of 3° and 5° slopes showed high DOM bioavailability, while the downslope soil of the 8° slope showed high DOM bioavailability. The content of new DOM in downslope soil increased with the gradient. Bacteria played an important role in the synthesis and transformation of DOM and affected its composition and slope distribution. Verrucomicrobiota, Firmicutes, Planctomycetota, and Gemmatimonadota were the main factors affecting soil DOM. The results could be helpful in understanding the loss mechanism of DOM in eroded black soil and provide support for soil carbon sequestration.

Corrosion Dynamics of Carbon-Supported Platinum Electrocatalysts with Metal-Carbon Interactions Revealed by In Situ Liquid Transmission Electron Microscopy.

Carbon support is essential for electrocatalysis, but limitations remain, as carbon corrosion can lead to electrocatalyst degradation and affect the long-term durability of electrocatalysts. Here, we studied the corrosion dynamics of carbon nanotubes (CNTs) and Vulcan carbon (VC) together with platinum (Pt) nanoparticles in real time by liquid cell (LC) transmission electron microscopy (TEM). The results showed that CNTs with a high degree of graphitization exhibited higher corrosion resistance compared to VC. Furthermore, we observed that the main degradation path of Pt nanoparticles in Pt/CNTs was ripening, while in Pt/VC, it was aggregation and coalescence, which was dominated by the interactions between Pt nanoparticles and different hybridization of carbon supports. Finally, we performed an ex situ CV stability test to confirm the conclusions obtained from in situ experiments. This work provides deep insights into the corrosion mechanism of carbon-supported electrocatalysts to optimize the design of electrocatalysts with a higher durability.

Attribution of Moisture Sources for Summer Precipitation in the Upstream Catchment of the Three Gorges Dam

Abstract Currently, there is a lack of investigating moisture sources for precipitation over the upstream catchment of the Three Gorges Dam (UCTGD), the world’s largest dam. Using the dynamical recycling model (DRM), trajectory frequency method (TFM), and the Climate Forecast System Reanalysis (CFSR), this study quantifies moisture sources and transport paths for UCTGD summer precipitation from 1980 to 2009 based on two categories of sources: region-specific and source-direction. Overall, the land and oceanic sources contribute roughly 63% and 37%, respectively, of the moisture to UCTGD summer precipitation. UCTGD and the Indian Ocean are the most important land and oceanic sources, respectively, in which the southern Indian Ocean with over 10% of moisture contribution was overlooked previously. Under the influence of the Asian monsoon and prevailing westerlies, the land contribution decreases to 57.3% in June, then gradually increases to 68.8%. It is found that for drought years with enhanced southwest monsoon, there is a weakening of the moisture contribution from the C-shaped belt along the Arabian Sea, South Asia, and UCTGD, and vice versa. TFM results show three main moisture transport paths and highlight the importance of moisture from the southwest. Comparison analysis indicates that, generally, sink regions are more affected by land evaporation with their locations more interior to the center of the mainland. Furthermore, correlations between moisture contributions and indices of general circulation and sea surface temperature are investigated, suggesting that these indices affect precipitation by influencing moisture contributions of the subregions. All of these are useful for comprehending the causes of summer UCTGD precipitation. Significance Statement Quantitative research on the moisture sources of summer precipitation has been implemented for the upstream catchment of the Three Gorges Dam (UCTGD), which is of particular hydrological significance but has not been investigated previously. The dynamical recycling model (DRM)–trajectory frequency method (TFM) approach is used to quantify and interpret the results of the moisture sources both in different specific subregions and directions, which produce more meaningful results than a single method for the areal division of moisture sources. Furthermore, antecedent indices that significantly influence the following moisture contributions of the subregions and then summer UCTGD precipitation are studied in terms of large-scale general circulation indices, which would help our understanding of precipitation forecast for UCTGD.

On the Influence of Wave-Shaped Tool Path Strategies on Geometric Accuracy in Incremental Sheet Forming

In incremental sheet forming (ISF), the geometrical accuracy is still a challenge that is only solved for specific applications. The underlying mechanisms of geometrical defects in ISF are very complex and still not fully understood. Nevertheless, the process understanding is constantly evolving. Recent work has shown, for example, how bending moments resulting from residual stresses affect geometric accuracy. It has become clear that resulting bending moments with an axis parallel to the main tool path direction are dominant. Based on that, the current paper investigates the hypothesis that linear and parallel tool paths lead to an unfavourable accumulation of residual bending moments along a common axis, and whether this accumulation effect can be reduced by wave-shaped tool paths. Thus, the described research investigates the influence of novel path strategies on the residual bending moments and the resulting geometrical deviations. The path strategies are based on wave-shaped path lines, whereas the curvature is within the sheet plane. The investigations focussed on a rectangular sheet that is clamped at its shortest edges and a part geometry-sensitive to springback. Experimental and numerical investigations show a significantly positive influence of some investigated path strategies on the geometric deviation, compared to a conventional path strategy.

Coupling input and output intensity to explore the sustainable agriculture intensification path in mainland China

Sustainable intensification (SI) of agriculture is widely regarded as an important way to alleviate the contradiction between the food gap and ecosystem health. Correlate input intensity and output intensity have been regarded as an important dimension in most estimation frameworks of SI. But in practice, this correlation is generally expressed in terms of efficiency metrics and calculated as the ratio of output intensity to input intensity, which cannot quantitatively explain the impact of input intensity on output intensity and provide a threshold value for estimating the suitability of SI. This study's goals are to propose an input—output coupled method to explain the impact of input intensity on output intensity and thereby estimate the suitability of provincial SI. Provincial annual input intensity and output intensity were estimated from an emergy-based perspective by taking China as a case study. The K-means algorithm was used to identify the structural pattern of arable land input intensity. A sliding window-based partial correlation index method was proposed and applied to reveal the interaction process between input intensity and output intensity. The results show that there are two main change paths in the pattern of input intensity: one path in the western irrigation regions and the other path in the eastern northeast China Plain and middle-lower Yangtze Plain. The former path can be expressed as a small increase in fertilizer and agro-machinery input intensity with a decrease in labour force input intensity. The latter path shows a larger increase in fertilizer and pesticide input intensity. For each type of input intensity except mulching film, its correlation to output intensity has experienced a similar coupling—decoupling—recoupling process in both plain provinces and mountainous or plateau provinces. According to Landau's theory of phase transition, the complex coupling of input and output undergoes a phase transition process from order to disorder and then to order, depicted by the sliding window-based partial correlation coefficient as the order parameter from a holistic perspective. The inflection points of coupling relation changes show that the phenomenon of fertilizer and pesticide overuse has steadily occupied most provinces in eastern China and is spreading westwards. Although the “zero growth action for fertilizers and pesticides” has made considerable achievements in reducing the input intensity of fertilizer and pesticides since 2015, the situation of superfluous fertilizer and pesticide input has not changed substantially. The input intensity of fertilizer and pesticides still needs to be further reduced. This study can contribute to the estimation method system of SI. The input—output coupled method is applicable for other spatial scales and regions (or countries) to estimate the suitability of SI.

Exploring the development trajectory of decent work literature: An empowerment perspective

The eighth United Nations Sustainable Development Goal (SDG) underscores the need to encourage inclusive and sustainable economic growth, while advancing full employment and ensuring decent work for all. This increased emphasis on decent work has garnered heightened attention from international organizations and businesses. Significantly, as laws pertaining to workers' rights and labor matters have evolved, the concept of decent work has continuously expanded. This study acknowledges that this dynamic nature of decent work poses challenges for businesses in devising appropriate policies. To gain better understanding of the shifting labor paradigm, this research employs a systematic review approach, specifically main path analysis (MPA), to trace the trajectory of decent work literature over the past two decades. Among the 737 articles retrieved on decent work, 23 critical papers are identified for in-depth analysis. The findings reveal that the research focus has evolved across three distinct stages: economic-oriented, identity-oriented, and culturally-oriented decent work. In response to this insight, this study proposes a comprehensive empowerment model to support organizations and decision-makers in promoting decent work and improving working conditions, ultimately contributing to inclusive growth. Furthermore, this study addresses the challenges associated with decent work, aiming to facilitate progress towards fair employment and sustainable workplaces.

From hype to reality: the changing landscape of MOOC research

PurposeThis paper examines the evolution of massive open online courses (MOOCs) literature over the past 15 years and identifies its significant developments.Design/methodology/approachUtilizing main path analysis (MPA) on a dataset of 1,613 articles from the Web of Science (WoS) databases, the authors construct the main pathway in MOOC literature through a citation analysis. Pajek software is used to visualize the 34 influential articles identified in the field.FindingsThree phases emerge in MOOC research: connectivism as a learning theory, facilitating education reform and breaking barriers to MOOCs adoption. Multiple-Global MPA highlights sub-themes including self-regulated learning (SRL), motivation, engagement, dropouts, student performance and the impact of COVID-19.Research limitations/implicationsFirst, data limitations from the WoS core collection might not cover all research, but using reputable sources enhances data validity. Second, despite careful algorithm selection to enhance accuracy, there remains a limitation inherent in the nature of citations. Such biased citations may result in findings that do not fully align with scholars' perspectives.Practical implicationsThe authors' findings contribute to the understanding of MOOCs literature development, enabling educators and researchers to grasp key trends and focus areas in the field. It can inform the design and implementation of MOOCs for more effective educational outcomes.Originality/valueThis study presents novel methodologies and important findings for advancing research and practice in MOOCs.

The Constitutional Relevance of the ECHR in Domestic Law: The Kosovo Perspective

Abstract This article examines the status and importance of the European Convention on Human Rights (ECHR) and European Court of Human Rights (ECtHR) Jurisprudence in the national legal system of the Republic of Kosovo. This will be accomplished by pursuing two main paths: first, by a doctrinal analysis of the constitutional status of the ECHR and the Jurisprudence of the ECtHR in Kosovo and, second, through a closer examination and analysis of specific cases as to the level of their (non) implementation by the Constitutional Court and regular courts of Kosovo. Even though Kosovo is not a member of the Council of Europe and has not ratified the ECHR, the ECHR has a specific and privileged place in the legal system of Kosovo and is part of its constitution. This makes Kosovo a very special case regarding the technique chosen for the incorporation of international instruments for human rights in its internal legal order. Public authorities in Kosovo agree to the obligation that the scope and meaning of fundamental rights should always be determined based on the standards established in Strasbourg. However, implementing these Strasbourg-derived standards is not simple or easy. Some of the elements identified for the application of these standards in internal judicial practice include the degree and measure of implementation, the methodology of choosing cases, the methods of interpretation, and local legal culture. This article, explains these elements by analyzing statistical data and specific court cases.

Synthesis of high‐quality vanadium nitride particles by one‐step vacuum carbothermal reduction–nitridation method: Theoretical and experimental study

AbstractOwing to its high hardness, favorable stability, and good electrical performance, vanadium nitride (VN) has been extensively used as an alloy additive, an electrode material, a ceramic material, and a catalyst. However, traditional VN synthesis methods require high temperatures and long soaking times. In this study, high‐quality VN particles were prepared from V2O3 powder at a lower temperature and shorter soaking time by a one‐step vacuum carbothermal reduction–nitridation (VCRN) method. Thermodynamic and kinetic analyses elucidated the mechanism of this process. Thermodynamic analysis showed that vacuum was conducive to the carbothermal reduction of V2O3, reducing the initial reaction temperature, and the main reaction path was V2O3→VO→VxCy(VC/ V2C/ V8C7/ V6C5)→VN. Kinetic results indicated that the one‐step VCRN method was a gas–solid reaction. Within the temperature range of 1373–1473 K, the rate‐determining step was controlled by the carbothermal reduction–nitridation reaction, combination control of the reduction–nitridation reaction and the interlayer diffusion, and interlayer diffusion control of N2 during the different reaction processes. High‐quality VN particles obtained at a temperature of 1473 K, pressure of 300 Pa, and soaking time of 3 h were characterized by X‐ray diffraction, transmission electron microscopy, energy dispersive X‐ray spectroscopy, and particle size distributions. The O and N contents, measured by an O/N analyzer, were 0.85% and 19%, respectively, and the C content, measured by a C/S analyzer, was 0.92%. These analyses indicate that high‐quality VN can be obtained by a one‐step VCRN method.

Disruptive development path measurement for emerging technologies based on the patent citation network

Studying disruptive innovation development paths for emerging technologies helps trace and grasp key core technologies development, promoting innovation and development in emerging technologies and industries. This paper measures the innovation development path for emerging technology, including: (1) improving the triple citation network and quantifying disruptive measurement by designing a technological disruption model; (2) proposing a contraction method for the citation network from the dataset perspective; (3) proposing a method to extract the main path using technology disruption degree as a criterion for citation networks importance; (4) taking the sintering technology in 3-D printing technology as the empirical object with 12,662 patent families from 1997 to 2019. The empirical results indicate that the disruption degree value is determined by the transitive citation relationship without the co-citation relationship, and the closed-loop structures are effectively removed, thereby reducing the size of the dataset. The proposed disruption quantification method can support effective evaluation of technological innovation levels and decision-making for the research and development (R&D) direction and resource allocation.

Comparison of fatigue crack growth behaviour in electron-beam and laser powder-bed-fusion Inconel 718

A comparative study on fatigue crack growth behaviour was made between the electron-beam powder-bed-fusion (PBF-EB) and laser powder-bed-fusion (PBF-LB) Inconel 718. The crack followed a transgranular path with a faster propagation rate for the PBF-EB Inconel 718, whereas a combination of intergranular and transgranular path was observed for the PBF-LB, and its slower rate being comparable to the wrought counterpart. The main fatigue crack in the PBF-EB Inconel 718 exhibited a sawtooth shaped path at the micro-scale, with intensive slip traces close to the crack surfaces owing to the very low work hardening rate. Based on the digital image correlation (DIC) analysis of the crack tip field, fatigue-crack sawtooth path in the PBF-EB Inconel 718 can be successfully predicted by using a strain energy density criterion, which dictates the crack growth follows the direction of minimum distance from the crack tip to elasto-plastic boundary. For the PBF-LB Inconel 718, the predominant fatigue crack was straight at low ΔK, but severe deflections occurred at the medium and high ΔK regimes. A clear correlation exists between the incipient intergranular cracks and the main crack path deflection. This suggests that once the accumulated damage in the plastic zone around the crack tip reaches the critical value, intergranular cracks can form the new front of the fatigue crack, causing the main crack path deflection. Elasto-plastic fracture mechanics parameters of rp and ΔCTOD, derived from the DIC-based crack tip field analysis, can qualitatively predict the lower crack growth rate of the PBF-LB Inconel 718.