Ensuring operational safety and reliability in Unmanned Aerial Vehicles (UAVs) necessitates advanced onboard fault detection. This paper presents a novel, mobility-aware multi-sensor health monitoring framework, uniquely fusing visual (camera) and vibration (IMU) data for enhanced near real-time inference of rotor and structural faults. Our approach is tailored for resource-constrained flight controllers (e.g., Pixhawk) without auxiliary hardware, utilizing standard flight logs. Validated on a 40 kg-class UAV with induced rotor damage (10% blade loss) over 100+ minutes of flight, the system demonstrated strong performance: a Multi-Layer Perceptron (MLP) achieved an RMSE of 0.1414 and R² of 0.92 for rotor imbalance, while a Convolutional Neural Network (CNN) detected visual anomalies. Significantly, incorporating UAV mobility context reduced false positives by over 30%. This work demonstrates a practical pathway to deploying sophisticated, lightweight diagnostic models on standard UAV hardware, supporting real-time onboard fault inference and paving the way for more autonomous and resilient health-aware aerial systems.
Ti-6Al-4V alloy is widely utilized in aerospace and medical sectors due to its high specific strength, corrosion resistance, and biocompatibility. However, its low machinability makes it difficult to manufacture complex-shaped products. Advancements in additive manufacturing have focused on producing high-performance, complex components using the laser powder bed fusion (LPBF) process, which is a specialized technique for customized geometries. The LPBF process exposes materials to extreme thermal conditions and rapid cooling rates, leading to residual stresses within the parts. These stresses are intensified by variations in the thermal history across regions of the component. These variations result in differences in microstructure and mechanical properties, causing distortion. Although support structure design has been researched to minimize residual stress, few studies have conducted quantitative analyses of stress variations due to different support designs. This study investigated changes in the residual stress and mechanical properties of Ti-6Al-4V alloy fabricated using LPBF, focusing on support structure design.
In this study, the effect of build orientation on the mechanical properties of Hastelloy X fabricated by laser powder bed fusion (LPBF) process was investigated. Initial microstructural analysis revealed an equiaxed grain structure with random crystallographic orientation and annealing twins. Intragranular precipitates identified as Cr-rich M23C6 and Mo-rich M6C carbides were observed, along with a dense dislocation network and localized dislocation accumulation around the carbides. Mechanical testing showed negligible variation in yield strength with respect to build orientation; however, both ultimate tensile strength and elongation exhibited a clear increasing trend with higher build angles. Notably, the specimen built at 90° exhibited approximately 22% higher tensile strength and more than twice the elongation compared to the 0° specimen.
This study investigated the ultra-low-temperature (4.2 K) tensile properties and deformation mechanisms of stainless steel 304L manufactured via laser powder bed fusion (LPBF). The tensile properties of LPBF 304L were compared to those of conventional 304L to assess its suitability for cryogenic applications. The results revealed that LPBF 304L exhibited a significantly higher yield strength but lower ultimate tensile strength and elongation than conventional 304L at 4.2 K. The temperature dependence of the yield strength also favored LPBF 304L. Microstructural analysis demonstrated that LPBF 304L features a high density of dislocation cells and nano-inclusions, contributing to its greater strength. Furthermore, strain-induced martensitic transformation was observed as a key deformation mechanism at cryogenic temperatures, where austenite transformed into both hexagonal-closed packed (HCP) and body-centered cubic (BCC) martensite. Notably, BCC martensite nucleation occurred within a single HCP band. These findings provide critical insights into the mechanical behavior of LPBF 304L at cryogenic temperatures and its potential for applications in extreme environments.
Metal additive manufacturing (AM) facilitates the production of complex geometries with enhanced functionality. Among various AM techniques, laser powder bed fusion (LPBF) is distinguished by its precision and exceptional mechanical properties achieved via laser fusion deposition. Recent advancements in AM have focused on combining LPBF with post-processing methods such as cold rolling, high-pressure torsion, and forming processes. Therefore, understanding the forming behavior of LPBF-processed materials is essential for industrial adoption. This study investigates the stretch-flangeability of LPBF-fabricated 316L stainless steel, emphasizing its anisotropic microstructure and mechanical properties. Hole expansion tests were employed to assess stretch-flangeability in comparison to wrought 316L stainless steel. The results demonstrate that LPBF-processed samples exhibit significant anisotropic behavior, demonstrating the influence of microstructural evolution on formability. These findings contribute valuable insights into optimizing LPBF materials for industrial forming applications.
This study investigated the effect of the hatch spacing parameter on the microstructure and mechanical properties of SA508 Gr.3 steel manufactured by laser powder bed fusion (L-PBF) for a nuclear pressure vessel. Materials were prepared with varying hatch spacing (0.04 mm [H4] and 0.06 mm [H6]). The H4 exhibited finer and more uniformly distributed grains, while the H6 showed less porosity and a lower defect fraction. The yield strength of the H4 material was higher than that of the H6 material, but there was a smaller difference between the materials in tensile strength. The measured elongation was 5.65% for the H4 material and 10.41% for the H6 material, showing a significantly higher value for H6. An explanation for this is that although the H4 material had a microstructure of small and uniform grains, it contained larger and more numerous pore defects than the H6 material, facilitating stress concentration and the initiation of microcracks.
Additive manufacturing makes it possible to improve the mechanical properties of alloys through segregation engineering of specific alloying elements into the dislocation cell structure. In this study, we investigated the mechanical and microstructural characteristics of CoNi-based medium-entropy alloys (MEAs), including the refractory alloying element Mo with a large atomic radius, manufactured via laser-powder bed fusion (L-PBF). In an analysis of the printability depending on the processing parameters, we achieved a high compressive yield strength up to 653 MPa in L-PBF for (CoNi)85Mo15 MEAs. However, severe residual stress remained at high-angle grain boundaries, and a brittle μ phase was precipitated at Mo-segregated dislocation cells. These resulted in hot-cracking behaviors in (CoNi)85Mo15 MEAs during L-PBF. These findings highlight the need for further research to adjust the Mo content and processing techniques to mitigate cracking behaviors in L-PBF-manufactured (CoNi)85Mo15 MEAs.
This study investigated the optimal process conditions and mechanical properties of Cu-10Sn alloys produced by the powder bed fusion (PBF) method. The optimal PBF conditions were explored by producing samples with various laser scanning speeds and laser power. It was found that under optimized conditions, samples with a density close to the theoretical density could be fabricated using PBF without any serious defects. The microstructure and mechanical properties of samples produced under optimized conditions were investigated and compared with a commercial alloy produced by the conventional method. The hardness, maximum tensile strength, and elongation of the samples were significantly higher than those of the commercially available cast alloy with the same chemical composition. Based on these results, it is expected to be possible to use the PBF technique to manufacture Cu-10Sn products with complex 3D shapes that could not be made using the conventional manufacturing method.
본 연구는 로파이 걸과 포트나이트의 협업 사례를 통해 게임과 음악 IP 융합의 비즈니스 모델을 분석했다. 비즈니스 모델 캔버스를 활용한 질적 사례 분석 방법을 사용했으며, 공식 발표 자료, 뉴스 기사, 업계 보 고서 등의 2차 자료를 분석했다. 연구 결과, '가치 제안' 면에서 로파이 걸 세계관의 게임 내 구현과 실시간 음악 스트리밍의 결합으로 독특한 경험을 제공했다. '채널 전략'으로는 게임 플랫폼, 유튜브 등 멀티채널 접근을 활용했다. '고객 관계' 측면에서는 게임 내 커뮤니티 형성과 실시 간 소통을 통해 사용자 참여를 극대화했다. '수익원'은 게임 내 아이템 판매, 음악 스트리밍 수익 등으로 다각화했다. '핵심 자원'으로는 로파이 걸 IP, 포트나이트 게임 엔진 등이 활용되었고, '핵심 활동'으로는 게임 업데이트, 음악 큐레이션 등이 수행되었다. '핵심 파트너십'은 음악 아티 스트, 스트리밍 플랫폼 등과 이루어졌으며, '비용 구조'는 게임 개발, 음 악 라이센싱, 마케팅 비용 등으로 구성되었다. 또한, 크로스 미디어 전략 의 주요 특징은 음악과 게임을 융합하는 미디어 간 경계 허물기, 2D에서 3D를 연결하는 IP의 확장을 통한 재해석 그리고 멀티 플랫폼 전략 등이 확인되었다. 본 연구 결과를 통해, 디지털 엔터테인먼트 산업의 크로스 미디어 전략의 IP 확장, 사용자 경험 혁신, 다각화된 수익 모델은 새로운 비즈니스 기회를 제시하며, 정책적 대안으로 크로스 미디어 협업 지원 체계 마련, IP 활용 창작자 지원 등의 투자 정책 수립 등이 필요하다.
In order to predict the process window of laser powder bed fusion (LPBF) for printing metallic components, the calculation of volumetric energy density (VED) has been widely calculated for controlling process parameters. However, because it is assumed that the process parameters contribute equally to heat input, the VED still has limitation for predicting the process window of LPBF-processed materials. In this study, an explainable machine learning (xML) approach was adopted to predict and understand the contribution of each process parameter to defect evolution in Ti alloys in the LPBF process. Various ML models were trained, and the Shapley additive explanation method was adopted to quantify the importance of each process parameter. This study can offer effective guidelines for fine-tuning process parameters to fabricate high-quality products using LPBF.
Chinese traditional music is a representation of the intellectual accomplishments of the Chinese people and holds significant cultural and artistic attributes. To effectively showcase it to the general audience, it is necessary to implement visual design techniques that concentrate on the innovative progression of Chinese traditional music. This paper analyses the practical significance of visual design in the context of Chinese traditional music, using the unique characteristics of this music as a starting point. The paper maintains a clear structure with logical progression, ensuring a logical flow of information with causal connections between statements. Technical term abbreviations are explained when first used, and precise subject-specific vocabulary is employed where appropriate. The language used is formal and free from grammatical errors, while the text adheres to a consistent footnote style, format, and citation. Biased language is avoided, with positions on subjects made clear through hedging. Finally, conventional academic sections are included and titles are factual, unambiguous, and occasionally employ freer wording for interest. In addition, it examines the visual representation of Chinese traditional music. Building on this groundwork, the paper delves into a case study concentrating on “Four Seasons Scenery” to embark on a research journey and practical exploration of the visual design of Chinese traditional music. Through a combination of scholarly inquiry and practical application, the aspiration is that this pursuit may offer new perspectives and methodologies for the perpetuation and innovation of Chinese traditional music.
The emergence of ferrous-medium entropy alloys (FeMEAs) with excellent tensile properties represents a potential direction for designing alloys based on metastable engineering. In this study, an FeMEA is successfully fabricated using laser powder bed fusion (LPBF), a metal additive manufacturing technology. Tensile tests are conducted on the LPBF-processed FeMEA at room temperature and cryogenic temperatures (77 K). At 77 K, the LPBF-processed FeMEA exhibits high yield strength and excellent ultimate tensile strength through active deformation-induced martensitic transformation. Furthermore, due to the low stability of the face-centered cubic (FCC) phase of the LPBFprocessed FeMEA based on nano-scale solute heterogeneity, stress-induced martensitic transformation occurs, accompanied by the appearance of a yield point phenomenon during cryogenic tensile deformation. This study elucidates the origin of the yield point phenomenon and deformation behavior of the FeMEA at 77 K.
Previous studies have shown that proline mutations in the heptad repeat region stabilize the coronavirus spike (S) protein in a pre-fusion state. To understand the impact of proline substitutions on the fusogenicity of the S protein, we engineered the swine acute diarrhea syndrome coronavirus (SADS-CoV) S protein with two proline substitutions (S-PP) and examined its fusogenicity using dual-split-protein based cell-cell fusion assay. Unlike the wild-type S (S-WT), S-PP rarely formed syncytia. Additionally, protein expression of S-PP was impaired compared to S-WT, as previously reported. Our results indicate that pre-fusion stabilized S protein is unable to induce membrane fusion and provide a better understanding of SADS-CoV S and vaccine antigen design.
In this study, machine learning models are proposed to predict the Vickers hardness of AlSi10Mg alloys fabricated by laser powder bed fusion (LPBF). A total of 113 utilizable datasets were collected from the literature. The hyperparameters of the machine-learning models were adjusted to select an accurate predictive model. The random forest regression (RFR) model showed the best performance compared to support vector regression, artificial neural networks, and k-nearest neighbors. The variable importance and prediction mechanisms of the RFR were discussed by Shapley additive explanation (SHAP). Aging time had the greatest influence on the Vickers hardness, followed by solution time, solution temperature, layer thickness, scan speed, power, aging temperature, average particle size, and hatching distance. Detailed prediction mechanisms for RFR are analyzed using SHAP dependence plots.
The Ti-6Al-4V lattice structure is widely used in the aerospace industry owing to its high specific strength, specific stiffness, and energy absorption. The quality, performance, and surface roughness of the additively manufactured parts are significantly dependent on various process parameters. Therefore, it is important to study process parameter optimization for relative density and surface roughness control. Here, the part density and surface roughness are examined according to the hatching space, laser power, and scan rotation during laser-powder bed fusion (LPBF), and the optimal process parameters for LPBF are investigated. It has high density and low surface roughness in the specific process parameter ranges of hatching space (0.06–0.12 mm), laser power (225–325 W), and scan rotation (15°). In addition, to investigate the compressive behavior of the lattice structure, a finite element analysis is performed based on the homogenization method. Finite element analysis using the homogenization method indicates that the number of elements decreases from 437,710 to 27 and the analysis time decreases from 3,360 to 9 s. In addition, to verify the reliability of this method, stress–strain data from the compression test and analysis are compared.
Although the Ti–6Al–4V alloy has been used in the aircraft industry owing to its excellent mechanical properties and low density, the low formability of the alloy hinders broadening its applications. Recently, laser-powder bed fusion (L-PBF) has become a novel process for overcoming the limitations of the alloy (i.e., low formability), owing to the high degree of design freedom for the geometry of products having outstanding performance used in hightech applications. In this study, to investigate the effect of bulk shape on the microstructure and mechanical properties of L-PBFed Ti-6Al-4V alloys, two types of samples are fabricated using L-PBF: thick and thin samples. The thick sample exhibits lower strength and higher ductility than the thin sample owing to the larger grain size and lower residual dislocation density of the thick sample because of the heat input during the L-PBF process.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein mediates virus entry by binding to the host cell receptor, human angiotensin converting enzyme 2 (hACE2), and catalyzing virus–host membrane fusion. The S protein also mediates cell–cell fusion, potentially allowing the virus to spread virion-independently. Here, we compared the fusogenicity of SARS-CoV-2 variant S proteins using a cell–cell fusion assay. In cells overexpressing hACE2, cell–cell fusion ability of all tested SARS-CoV-2 variants was similar to that of the Wuhan-Hu-1 strain. However, in cells with endogenous hACE2, SARS-CoV-2 variants, especially the Delta variant, stimulated significantly greater cell–cell fusion than the original strain. Our results showed that the Delta variant S protein is highly fusogenic and can spread rapidly by utilizing small amounts of hACE2.