Joint Formation Research Articles

Effect of temperature profile and chemical composition of the flux on void formation in solder joints: in-depth analysis

Effect of temperature profile and chemical composition of the flux on void formation in solder joints: in-depth analysis

CETN: Contrast-enhanced Through Network for Click-Through Rate Prediction

Click-through rate (CTR) prediction is a crucial task in personalized information retrievals, such as industrial recommender systems, online advertising, and web search. Most existing CTR Prediction models utilize explicit feature interactions to overcome the performance bottleneck of implicit feature interactions. Hence, deep CTR models based on parallel structures (e.g., DCN, FinalMLP, xDeepFM) have been proposed to obtain joint information from different semantic spaces. However, these parallel subcomponents lack effective supervision and communication signals, making it challenging to efficiently capture valuable multi-views feature interaction information in different semantic spaces. To address these issues, we propose a simple yet effective novel CTR model: Contrast-enhanced Through Network (CETN). Drawing inspiration from sociology, CETN leverages the complementary nature of diversity and homogeneity to guide the model in acquiring higher-quality feature interaction information. Specifically, CETN employs product-based feature interactions and the augmentation (perturbation) concept from contrastive learning to segment different semantic spaces, each with distinct activation functions. This improves diversity in the feature interaction information captured by the model. Additionally, we introduce self-supervised signals and through connection within each semantic space to ensure the homogeneity of the captured feature interaction information. The experiments conduct on four real datasets demonstrate that our model consistently outperforms twenty baseline models in terms of AUC and Logloss.

In‐situ fabrication of high‐strength SiC joints utilizing a novel CoCrFeNiTiMo high‐entropy alloy filler

AbstractThis study utilized an innovative unalloyed CoCrFeNiTiMo hybrid powder as a joining filler to fabricate high‐strength SiC/HEA/SiC joints via in‐situ reaction. The investigation systematically examines the effects of joining parameters on microstructural evolution and mechanical properties. The filler exhibits high reactivity with SiC, addressing carbon enrichment and low‐strength issues. The resulting joining layer comprises HEA‐rich Si, Mo1.5Cr1.5Si, MoTiC2, and TiC phases. Increasing the temperature facilitates carbon diffusion, transforming TiC into MoTiC2 and forming a MoTiC2‐wrapped TiC structure. At 1400°C for 60 min, the joints attain peak flexural and shear strengths of 312 ± 16 and 137 ± 10 MPa, respectively. Additionally, the joints demonstrate excellent oxidation resistance, with a residual strength of 270 ± 7 MPa after 20 h at 900°C, and favorable high‐temperature mechanical strength, retaining 155 ± 14 MPa at 1000°C. A detailed analysis of the joint formation mechanism is conducted based on experimental results and first‐principles calculations.

Joint Quality Assessment of Ultrasonic Metal Welded Parts by Fracture Surface Evaluation

In ultrasonic metal welding, low specific resistances and large joining surface cross-sections require the use of mechanical testing to quantify the joint quality. In this study, different quality features of ultrasonically welded joints made of pure copper sheet are investigated during the successive phases of joint formation. Two test series with different workpiece geometries are examined. It is shown that mechanical quality features such as shear and peel forces behave differently over the formation of the joint and are not transferable. As an alternative to these, laser scanning microscopy is used to record images of the fracture surface that describe the growth of the joint area during formation. The study finds that shear tensile force growth and joint area growth are non-linear and comparable, with optimized welds achieving joint areas of 30 mm2 out of 64 mm2 and 6 mm2 out of 16 mm2. Although overall quality increases with increasing welding time, the material strength in the joint zone decreases. Depending on the original rolling condition, between 43% and 59% of the original material strength can be identified as the joint strength. The automatic analysis of fracture images is a suitable alternative to mechanical testing for similar joints.

Experimental study on a novel reduced beam section self consolidating concrete‐filled double steel tube

AbstractThis study proposes a novel reduced beam section concrete‐filled double steel tube (RBS CFDST) beam‐to‐column joint and investigates the effect of RBS length and the beam moment of inertia on the plastic hinge formation in such joints. Therefore, a set of nine RBS CFDST connections were fabricated and cast with self‐consolidating concrete in the laboratory. Then, parameters including failure pattern, buckling mode, plastic hinge location, joint maximum load‐bearing capacity, and column rotation were inspected. The findings reveal that when the RBS length is equal to that of the beam dimension, the entire plastic hinge length is formed within the RBS zone. As such, the plastic hinge occurs away from the column face and brittle failure is avoided, while the joint column rotation is significantly reduced. It was also concluded that the maximum load‐bearing capacity is the highest when the RBS length is at its lowest.

Hand-Aware Graph Convolution Network for Skeleton-Based Sign Language Recognition

Skeleton-based Sign Language Recognition (SLR) is a challenging research area mainly due to the fast and complex hand movement. Currently, Graph Convolution Networks (GCNs) have been employed in skeleton-based SLR and achieved remarkable performance. However, existing GCN-based SLR methods suffer from a lack of explicit attention to hand topology which plays an important role in the sign language representation. To address this issue, we propose a novel Hand-Aware Graph Convolution Network (HA-GCN) to focus on hand topological relationships of skeleton graph. Specifically, a Hand-Aware Graph Convolution layer is designed to capture both global body and local hand information, in which two sub-graphs are defined and incorporated to represent hand topology information. In addition, in order to eliminate the over-fitting problem, an adaptive DropGraph is designed in construction of Hand-Aware Graph Convolution block to remove the spatial and temporal redundancy in the sign language representation. With the aim to further improve the performance, the joints information, bones, together with their motion information are simultaneously modeled in a multi-stream framework. Extensive experiments on the two open-source datasets, AUTSL and INCLUDE, demonstrate that our proposed algorithm outperforms the state-of-the-art with a significant margin. Our code is available at https://github.com/snorlaxse/HA-SLR-GCN.

Investigation of the influence of the rivet geometry on joint formation for a versatile self-piercing riveting process

Investigation of the influence of the rivet geometry on joint formation for a versatile self-piercing riveting process

Ultra-high temperature brazing of C/C using a simplified FeNiCrCu high-entropy alloy as filler

To increase remelting temperature of C/C brazed joint, a simplified FeNiCrCu high-entropy alloy (HEA) filler was designed in high-temperature brazing (HTB). The joint formation mechanism and fracture behavior were studied. The eutectic reaction of FeNiCrCu HEA with C/C could not occur, helping increase joint remelting temperature over HEA melting point (1334 °C). For the recommended parameter 1350 °C-2 min, dissolution of C/C occurred well, and no defect was observed both at interface and within bond seam. The maximum shear strength was 24.2 MPa due to the high strength in-situ (Cr,Fe)3C2 reinforced the high plastic Cu-Ni-Fe(S.S.) matrix and intimate wavy interface. Cr existed only in M3C2 in bond seam, reducing both carbon content and CTE of bond seam. For higher temperature and longer time, excessive dissolved carbon content resulted in the presence of large solidified carbon with defect at interface, joint shear strength decreased dramatically. These results provide a unique braze system for brazing carbon-based materials.

FGF Signaling Regulates Development of the Anterior Fontanelle.

The calvarial bones of the infant skull are connected by transient fibrous joints known as sutures and fontanelles, which are essential for reshaping during birth and postnatal growth. Genetic disorders such as Apert, Pfeiffer, Crouzon, and Bent bone dysplasia linked to FGFR2 variants often exhibit multi-suture craniosynostosis and a persistently open anterior fontanelle (AF). This study leverages mouse genetics and single-cell transcriptomics to determine how Fgfr2 regulates closure of the AF closure and its transformation into the frontal suture during postnatal development. We find that cells of the AF, marked by the tendon/ligament factor SCX, are spatially restricted to ecto- or endocranial domains and undergo regionally selective differentiation into ligament, bone, and cartilage. Differentiation of SCX+ AF cells is dependent on FGFR2 signaling in cells of the osteogenic fronts which, when fueled by FGF18 from the ectocranial mesenchyme, express the secreted WNT inhibitor WIF1 to regulate WNT signaling in neighboring AF cells. Upon loss of Fgfr2 , Wif1 expression is lost, and cells of the AF retain a connective tissue-like fate failing to form the posterior frontal suture. This study provides new insights into regional differences in suture development by identifying an FGF-WNT signaling circuit within the AF that links frontal bone advancement with suture joint formation.

High-strength and impermeable sapphire/aluminum joints fabricated by ultrafast laser microwelding: Microstructures and joining mechanism

In this work, robust joints of sapphire and aluminum were successfully achieved by direct ultrafast laser transmission microwelding. Effects of laser parameters on the microstructures and mechanical properties were comprehensively studied. The welding process highly depended on the laser ablated metal nanoparticles within the heterojunction, as well as the thermal accumulation under multiple laser pulses irradiation. It showed that lack of fusion at the sapphire/aluminum interface can occur due to the incomplete melting of ablated nanoparticles at low laser fluence (<0.48 J/cm2). While serious cavities and cracks inside the brittle sapphire were formed with the intensified stress concentration after melting-solidification process at excessive laser fluence (>0.64 J/cm2). A nearly defect-free joint was obtained with max. shear strength of 128.1 ± 8.2 MPa at room temperature, when the laser fluence was 0.56 J/cm2. The high shear strength can be attributed to the tortuous interface with wide elemental transition layer. Meanwhile, the welded sapphire/aluminum joints exhibited high reliability under extreme service temperatures, which the shear strength can reach 159.8 ± 8.96 MPa at −50 °C and 80.6 ± 11.1 MPa at 200 °C. The sealing tests also showed the excellent impermeability of laser welded sapphire/aluminum structure, confirming the micro-crack free joint formation. This work demonstrates the feasibility of using ultrafast laser to achieve high-quality sapphire/aluminum joint, which is promising in heat-dissipation substrate manufacturing in power semiconductor devices.

Model selection by pathwise marginal likelihood thresholding

We suggest to estimate a sparse parameter vector in multivariate models through the selection of marginal likelihoods from a potentially large set. The resulting estimator involves an adaptive thresholding mechanism, whereby the marginal estimates are set to zero according to their sequential contribution to the joint information computed along a path of increasingly complex models. The effectiveness of our proposal is illustrated via simulations.

Investigation of ultrasonic welding of CF/PA66 using nylon mesh energy directors

AbstractCarbon fiber reinforced polyamide 66 (CF/PA66) sheets are ultrasonically welded by applying nylon meshes as energy directors (EDs) in this paper. The influence of mesh dimensions is revealed by observing the joint formation process, joint mechanical performance, joint cross‐sectional morphology and joint failure mode. Results show that the joint formation process can be divided into wire flattening stage, ED spread stage, tight bonding stage, and mixing stage. The nylon mesh ED with moderate wire spacing, small wire diameter and small mesh area promotes better weld quality. Welding energy will be dispersed rather than concentrated if the mesh area is too large, resulting in reduced failure load. The joints exhibit two fracture modes: interfacial fracture (IF) and workpiece fracture (WF), and the fracture mode of the joints with nylon mesh EDs transits from IF to WF as the welding energy increases.Highlights Five types of nylon mesh are used as energy directors to join CF/PA66 sheets by ultrasonic welding. The influence of nylon mesh dimensions on the mechanical property and fracture mode of joints is investigated. The formation process of ultrasonically welded joints can be separated into wires flattening stage, ED spread stage, tight bonding stage, and mixing stage.

Survey assessing foot trimmer involvement in managing lameness in UK beef cattle.

Cattle lameness is a significant welfare and economic problem facing the livestock industry. Published research has investigated foot trimming practices in dairy herds, but little is known about the practices in beef herds. Therefore, the objective of this study was to obtain information about the current practices of professional cattle foot trimmers concerning beef cattle within the UK. An online survey comprising 16 questions was created using the Joint Information Systems Committee platform. The survey was open for 3 months. There was a significant difference (p<0.05) between the proportions of dairy cattle and beef cattle receiving preventative foot trims. Digital dermatitis was the most commonly recorded cause of lameness when a lame beef animal was trimmed by the respondents, followed by white line disease. A thematic analysis of foot trimmers' opinions of barriers to engagement on beef farms is presented, in addition to their opinions on veterinary involvement with beef lameness. Distribution bias may have affected the results, as the survey was distributed online with support from the Cattle Hoof Care Standards Board and the National Association of Cattle Hoof Trimmers. The percentage of foot trimmers not affiliated with either professional body is not known. Further research on the impact of lameness on suckler and finishing cattle, including investigations into preventative actions to reduce lameness in beef systems, is warranted.

Gene Expression Patterns and Phenotypic Associations in Chondrogenesis: Insights into Skeletal Dysplasia Nosology

The differentiation of mesenchymal stem cells (MSCs) into chondrocytes, known as chondrogenesis, is a complex process that plays a fundamental role in cartilage formation and skeletal development. This study elucidates the transcriptional dynamics and phenotypic correlations at various stages of chondrogenesis (early, mid, and late) using RNA-seq data. We focused on the differential expression of transcription factors (TFs) and RNA-binding proteins (RBPs). We identified critical genes during their highest expression periods and generated heatmaps to visualize these temporal patterns. Additionally, we conducted a comprehensive analysis of skeletal dysplasia nosology genes, determining their highest expression periods and phenotypic implications using the DisGeNET database. Our findings reveal that early-stage (D1) gene expression is linked to craniofacial development and limb formation anomalies, primarily involving genes responsible for extracellular matrix (ECM) organization and signal transduction. Mid-stage (D7) genes are associated with cartilage matrix composition and skeletal growth, highlighting roles in chondrocyte proliferation and matrix deposition. Late-stage (D21) genes are implicated in bone mineral density, cartilage integrity, and joint formation, ensuring the maturation and functionality of cartilage tissue. This study provides a detailed analysis of gene expression regulators and their phenotypic correlations during chondrogenesis, offering insights into the molecular mechanisms driving cartilage development and skeletal dysplasias. Understanding these temporal gene expression patterns enhances our knowledge of chondrogenesis and aids in developing targeted therapies for cartilage-related diseases. These findings underscore the significance of time-point analyses in capturing the dynamic regulation of gene expression throughout the differentiation process.

Quantum-enhanced joint estimation of phase and phase diffusion

Accurate phase estimation in the presence of unknown phase diffusive noise is a crucial yet challenging task in noisy quantum metrology. This problem is particularly interesting due to the detrimental impact of the associated noise. Here, we investigate the joint estimation of phase and phase diffusion using generalized Holland–Burnett states, known for their experimental accessibility. These states provide performance close to the optimal state in single-parameter phase estimation, even in the presence of photon losses. We adopt a twofold approach by analyzing the joint information extraction through the double homodyne measurement and the joint information availability across all probe states. Through our analysis, we find that the highest sensitivities are obtained by using states created by directing all input photons into one port of a balanced beam splitter. Furthermore, we infer that good levels of sensitivity persist even in the presence of moderate photon losses, illustrating the remarkable resilience of our probe states under lossy conditions.

Application of Friction Riveting technique for the assembly of electronic components on printed circuit boards (PCB)

This study focuses on the effects of reducing the diameter of rivets used in Friction Riveting due to the need for downscaling when joining assemblies on a smaller scale. The Friction Riveting process has shown promising feasibility for a variety of material combinations and applications in the transportation industry. Recent research has explored the potential application of this technique in electronics, specifically for the assembly of printed circuit boards (PCBs), using AA-2024-T351 rivets on thin glass-fiber-reinforced epoxy substrates (FR4). The joint formation of joints produced with PCBs was investigated in terms of process temperature evolution, microstructural changes, and mechanical properties. Joints were obtained at process temperatures ranging from 285 ºC to 368 ºC. The use of 4 mm rivets resulted in extensive delamination, weak joint mechanisms, and cracking, impaired by the different coefficients of thermal expansion of the materials involved. Reducing the rivet diameter to 3 mm significantly improved joint quality. A further reduction to 2.5 mm minimized delamination but led to insufficient anchorage and cracking. Joints produced with a 3 mm rivet diameter achieved the highest ultimate tensile force of 276 N. This study sets the foundation for applying the Friction Riveting process to practical PCB assemblies, demonstrating that optimizing the process parameters to the diameter-to-thickness ratio can balance sufficient rivet anchoring, minimize delamination, and reduce cracking.

Effect of the Ni plating on Al–Cu dissimilar metal laser welded joint

In this study, the joint strength and interfacial microstructure of Al–Cu laser welded joints are investigated to understand the effect of Ni plating. Cu without plating and Cu plated with 1 μm and 4 μm of Ni were laser welded with Al, respectively, and their differences in joint strength and microstructure were comparatively analyzed. Macrostructure observations showed that the plating had no effect on the change of weld pool shape. Lap shear tests revealed that there was a distinctive improvement in joint strength with the Ni plating. Under a 1.4 kW laser power condition, it was noted that the sample with 4 μm Ni plating showed a 49% increase in load and a 100% increase in elongation compared to the sample without plating. Fracture surface observations revealed that Ni addition has changed the crack propagation path resulting in the increased joint strength. Microstructural analysis showed that the Ni is occupied in intermetallic compounds (IMCs) such as Al3Cu2, AlCu, and Al2Cu3 developed at the interface between Cu and Al2Cu which were known as the primary crack propagation phase in Al–Cu laser welded joint. Additionally, increases in their thickness and changes in their shapes to irregular wavy forms were observed, potentially reducing load concentration and increasing joint surface area, facilitating stable joint formation. Density functional theory calculations showed that the IMCs with Ni undergo contraction in the cell volume suggesting solid solution strengthening of IMCs by Ni addition.

Empowering Indonesia's Defense: The Evolution of Smart Military Society in the Total People's War System

In the context of Indonesia's Total People’s War, the concept of a Smart Military Society emerges as a pivotal element in modern defense practices. This study aims to explore the integration of information technology, artificial intelligence, connectivity, and collaboration within military operations to construct an efficacious Smart Military Society. By harnessing the potential of ICT and smart technology, the Indonesian defense sector can effectively enhance situational awareness, decision-making processes, and response capabilities to address evolving threats. The collaboration with societal stakeholders, academia, and industries fosters innovation, adaptability, and the development of a technologically advanced defense industry. Through joint exercises and information sharing, the interoperability of defense forces improves, leading to coordinated efforts across different military components. Challenges such as cybersecurity measures must be addressed to safeguard sensitive information and critical infrastructure. The implementation of a Smart Military Society not only strengthens Indonesia's defense capabilities but also stimulates economic growth, promotes self-reliance, and enhances national security. This research contributes profound insights into the potential and challenges associated with Smart Military Society, offering valuable implications for adaptive defense strategies in the complexities of modern warfare.

Automatic detection of color markings and numbers on trees in point clouds from Personal Laser Scanning (PLS) and Terrestrial Laser Scanning (TLS)

In forestry, colored spray paint is used for different purposes, such as marking trees that are chosen for the next harvest or that will be promoted by future silvicultural activities, or for the demarcation of skid/cable roads. Numerous studies have demonstrated the application of Terrestrial Laser Scanners (TLS) and Personal Laser Scanners (PLS) for the acquisition of tree parameters (diameters, heights, and tree positions) in a forest inventory context. However, no studies have included classification based on spectral information by applying colored markings to trees. When a laser scanner is combined with a camera, the color information can be mapped onto the laser point cloud, allowing for additional analysis of spectral information. In this study, we have tested the analysis of joint information from imagery and 3D point clouds in two different settings: (i) PLS point cloud data from a GeoSLAM ZEB Horizon were complemented with spectral information from images collected with a NCTech iSTAR Pulsar 360-degree camera, (ii) TLS point cloud data from a RIEGL VZ-400i were combined with imagery from a Nikon D850 digital single lens reflex (DSLR) camera with 14 mm fisheye lens. The major objective was to automatically classify trees that were marked with colored sprays automatically identify the numbers sprayed on the trees. The marked trees could be classified correctly with a balanced accuracy of 77.26% for PLS and 98.01% for the data collected with the TLS system using a support vector machine (SVM) model. The numbers written on the trees were classified from the TLS data using a YOLOv8 model. The accuracy of the digit classification reached up to 97.30%. In conclusion, it is possible to automatically detect marked trees and to automatically recognize the numbers spayed on these trees from colored point cloud data. However, accuracy strongly depends on the selected combination of scanner and camera. The findings of future research on this subject might differ with the ongoing development of PLS systems and could be enhanced by creating a large dataset of handwritten numbers collected using laser scanning systems.

Stability assessment of jointed rock capturing roughness degradation under cyclic loading with special reference to railway formation

Repeated train loading on a jointed rock subgrade can cause excessive displacements of certain discontinuities leading to instability. Repeated shearing of discontinuities leads to a gradual reduction in joint roughness (i.e. wearing of asperities), which is quantified by the change in the joint roughness coefficient (JRC). This process reduces the joint shear strength over time. In this study, the classical shear strength criterion proposed by Barton and Choubey (1977) is extended to capture the influence of cyclic loading on joint degradation and the corresponding shear strength reduction, also considering the scale effect. This modified cyclic shear strength is implemented in FLAC-3D and validated with conventional cyclic triaxial data available from selected past studies. The model is applied to a simulated real-life track operating over a jointed sandstone formation commonly found towards the eastern coast of NSW. A modified limit equilibrium approach based on an Equivalent Factor of Safety (EFOS) is introduced and adopted to quantify the extent of instability, whereby an increase in the number of loading cycles affects a decrease in the EFOS of an unstable block. For a specific joint strike inclined to the track, the potential adversities are exacerbated when the joint dip angle is greater and when the initial JRC is smaller. In this paper, alternative geometrical combinations and different initial joint properties are considered to determine the worst combination of JRC and joint orientation upon cyclic train loading. As most past studies adhere to traditional static load analyses, the extended shear strength criterion described in this study is novel, and it offers significant practical benefit for railways that are subjected to prolonged cyclic loading.