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Search Results (417)

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Keywords = joint calibration

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14 pages, 9357 KiB  
Article
Design and Development of a Bespoke Rotary Friction Welding Machine in Exploration of Joining Dissimilar Materials for Nuclear Applications
by Michail Dellepiane, Laurie Da Silva and Athanasios Toumpis
J. Manuf. Mater. Process. 2025, 9(1), 27; https://doi.org/10.3390/jmmp9010027 - 18 Jan 2025
Viewed by 350
Abstract
Rotary friction welding is a solid-state welding process that can manufacture high-integrity joints between similar and dissimilar materials with short weld times. However, access to expensive and complex industrial-grade friction welding machines is not always possible. This study explores the design process and [...] Read more.
Rotary friction welding is a solid-state welding process that can manufacture high-integrity joints between similar and dissimilar materials with short weld times. However, access to expensive and complex industrial-grade friction welding machines is not always possible. This study explores the design process and functionality of a laboratory-scale friction welding setup following the fundamentals of large-scale machinery. The proposed setup is designed to be easily manufactured, employing the use of a calibrated drill press and load cell, thus ensuring welding parameters such as rotational speed and applied axial load are monitored. The decision to investigate rotary friction welding of aluminium bronze Ca104 to austenitic stainless steel AISI316 was taken to explore the limitations of this bespoke friction welding machine for prospective applications in the nuclear energy sector. The workpieces were friction welded at four sets of rotational speeds with constant friction and forging pressures. The microstructural evolution and mechanical properties of the dissimilar material welds were investigated via optical and scanning electron microscopy with energy dispersive spectroscopy, 4-point bend testing and microhardness measurements. Results show a change in the hardness along the weld interface and evidence of metallic diffusion between the dissimilar materials, demonstrating the successful application of the small-scale experimental setup. Full article
(This article belongs to the Special Issue Advances in Dissimilar Metal Joining and Welding)
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17 pages, 13183 KiB  
Article
Development of a Finite Element Model for the HAZ Temperature Field in Longitudinal Welding of Pipeline Steel
by Zhixing Wang, Chengjia Shang and Xuelin Wang
Metals 2025, 15(1), 91; https://doi.org/10.3390/met15010091 - 18 Jan 2025
Viewed by 357
Abstract
In this study, a novel hybrid heat source model was developed to simulate the welding temperature field in the heat-affected zone (HAZ) of X80 pipeline steel. This model replicates welding conditions with high accuracy and allows flexible three-dimensional adjustments to suit various scenarios. [...] Read more.
In this study, a novel hybrid heat source model was developed to simulate the welding temperature field in the heat-affected zone (HAZ) of X80 pipeline steel. This model replicates welding conditions with high accuracy and allows flexible three-dimensional adjustments to suit various scenarios. Its development involved the innovative integration of microstructural crystallography information with a multi-scale calibration and validation methodology. The methodology focused on three critical aspects: the weld interface morphology, the location of the Ac1 temperature, and the size of prior austenite grains (PAG). The morphology of the weld interface was calibrated to align closely with experimental observations. The model’s prediction of the Ac1 location in actual welded joints exhibited a deviation of less than ±0.3 mm. Furthermore, comparisons of reconstructed PAG sizes between thermal simulation samples and actual HAZ samples revealed minimal discrepancies (5 μm). Validation results confirmed that the calibrated model accurately describes the welding temperature field, with reconstructed PAG size differences between simulation and experimental results being less than 9 μm. These findings validate the accuracy of the calibrated model in predicting welding temperature fields. This research introduces a novel framework for the development of heat source models, offering a robust foundation for improving welding performance and controlling microstructure in different regions during the welding process of high-strength low-alloy (HSLA) steel. Full article
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20 pages, 6970 KiB  
Article
Analysis and Prediction of Grouting Reinforcement Performance of Broken Rock Considering Joint Morphology Characteristics
by Guanglin Liang, Linchong Huang and Chengyong Cao
Mathematics 2025, 13(2), 264; https://doi.org/10.3390/math13020264 - 15 Jan 2025
Viewed by 385
Abstract
In tunnel engineering, joint shear slip caused by external disturbances is a key factor contributing to landslides, instability of surrounding rock masses, and related hazards. Therefore, accurately characterizing the macromechanical properties of joints is essential for ensuring engineering safety. Given the significant influence [...] Read more.
In tunnel engineering, joint shear slip caused by external disturbances is a key factor contributing to landslides, instability of surrounding rock masses, and related hazards. Therefore, accurately characterizing the macromechanical properties of joints is essential for ensuring engineering safety. Given the significant influence of rock joint morphology on mechanical behavior, this study employs the frequency spectrum fractal dimension (D) and the frequency domain amplitude integral (Rq) as quantitative descriptors of joint morphology. Using Fourier transform techniques, a reconstruction method is developed to model joints with arbitrary shape characteristics. The numerical model is calibrated through 3D printing and direct shear tests. Systematic parameter analysis validates the selected quantitative indices as effective descriptors of joint morphology. Furthermore, multiple machine learning algorithms are employed to construct a robust predictive model. Machine learning, recognized as a rapidly advancing field, plays a pivotal role in data-driven engineering applications due to its powerful analytical capabilities. In this study, six algorithms—Random Forest (RF), Support Vector Regression (SVR), BP Neural Network, GA-BP Neural Network, Genetic Programming (GP), and ANN-based MCD—are evaluated using 300 samples. The performance of each algorithm is assessed through comparative analysis of their predictive accuracy based on correlation coefficients. The results demonstrate that all six algorithms achieve satisfactory predictive performance. Notably, the Random Forest (RF) algorithm excels in rapid and accurate predictions when handling similar training data, while the ANN-based MCD algorithm consistently delivers stable and precise results across diverse datasets. Full article
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33 pages, 23106 KiB  
Article
Determination of Mechanical Properties of Blind Rivet Joints Using Numerical Simulations and Experimental Testing
by Martin Beber, Martin Stejskal and Frantisek Sedlacek
Materials 2025, 18(2), 229; https://doi.org/10.3390/ma18020229 - 7 Jan 2025
Viewed by 443
Abstract
This study explores the tensile performance of blind rivet joints in galvanized steel sheets, focusing on their behavior under shear and normal load conditions. Blind rivets are frequently used in structural applications due to their ease of installation and ability to be applied [...] Read more.
This study explores the tensile performance of blind rivet joints in galvanized steel sheets, focusing on their behavior under shear and normal load conditions. Blind rivets are frequently used in structural applications due to their ease of installation and ability to be applied from one side, making them highly effective in industries like aerospace and automotive. Two types of DIN 7337—4.8 × 8 blind rivets—galvanized steel St/St and stainless steel A2/A2—paired with galvanized steel sheets DX51D + Z275, were experimentally tested to assess how their material properties affect their joint strength, deformation patterns, and failure modes. Single-lap shear, double-lap shear, and pure normal load tests were conducted in multiple configurations to evaluate joint performance under varying loading conditions, simulating real-world stresses. Using custom-built equipment, controlled forces were applied perpendicular to the rivet joints to replicate practical loading conditions. The results revealed distinct differences in the load-bearing capacities of the two materials, offering valuable insights for applications where corrosion resistance and structural integrity are critical. Finite element analysis (FEA) was then used to simulate the behavior of the joints, with the results validated against experimental data. To enhance the reliability of numerical simulations in optimizing the design of rivet joints, a methodology was proposed to calibrate non-linear FEA models to experimental results, and a substantial agreement of 92.53% was achieved via optimization in ANSYS OptiSLang. This research contributes to our broader understanding of riveted connections, providing practical recommendations for assessing the performance of such joints in various engineering fields. Full article
(This article belongs to the Section Materials Simulation and Design)
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21 pages, 11068 KiB  
Article
A Methodology for Assessing the Impact of In Situ Fractures on the Intensity of Blast-Induced Damage
by Omid Karimi, Marie-Helene Fillion and Philip Dirige
Mining 2025, 5(1), 7; https://doi.org/10.3390/mining5010007 - 7 Jan 2025
Viewed by 458
Abstract
Drilling and blasting is the conventional method used for rock fragmentation in open pit mining. Blast-induced damage can reduce the level of stability of benches and pit slopes. To develop an optimal blast design, an adequate knowledge of the rock properties and in [...] Read more.
Drilling and blasting is the conventional method used for rock fragmentation in open pit mining. Blast-induced damage can reduce the level of stability of benches and pit slopes. To develop an optimal blast design, an adequate knowledge of the rock properties and in situ fractures is needed. Fractures are generally the paths of least resistance for explosive energy and can affect the intensity of blast-induced damage. Discrete Fracture Networks (DFNs) are 3D representations of joint systems used for estimating the distribution of in situ fractures in a rock mass. The combined finite/discrete element method (FDEM) can be used to simulate the complex rock breakage process during a blast. The objective of this paper is to develop a methodology for assessing the influence of in situ joints on post-blast fracturing and the associated wall damage in 2D bench blast scenarios. First, a simple one-blasthole scenario is analyzed with the FDEM software Irazu 2D and calibrated based on a laboratory-scale blasting experiment available from previous literature. Secondly, more complex scenarios consisting of one-blasthole models at the bench scale were simulated. A bench blast without DFN (base case) and one with DFN were numerically simulated. The model with DFN demonstrated that the growth path and intensity of blast-induced fractures were governed by pre-existing fractures, which led to a smaller wall damage area. The damage intensity for the base case scenario is about 82% higher than for the blast model with DFN included, which highlights the significance of in situ fractures in the resulting blast damage intensity. The methodology for developing the DFN-included blasting simulation provides a more realistic modeling process for blast-induced wall damage assessment. This results in a better characterization of the blast damage zone and can lead to improved slope stability analyses. Full article
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22 pages, 14296 KiB  
Article
Calibration-Enhanced Multi-Awareness Network for Joint Classification of Hyperspectral and LiDAR Data
by Quan Zhang, Zheyuan Cui, Tianhang Wang, Zhaoxin Li and Yifan Xia
Electronics 2025, 14(1), 102; https://doi.org/10.3390/electronics14010102 - 30 Dec 2024
Viewed by 390
Abstract
Hyperspectral image (HSI) and light detection and ranging (LiDAR) data joint classification has been applied in the field of ground category recognition. However, existing methods still perform poorly in extracting high-dimensional features and elevation information, resulting in insufficient data classification accuracy. To address [...] Read more.
Hyperspectral image (HSI) and light detection and ranging (LiDAR) data joint classification has been applied in the field of ground category recognition. However, existing methods still perform poorly in extracting high-dimensional features and elevation information, resulting in insufficient data classification accuracy. To address this challenge, we propose a novel and efficient Calibration-Enhanced Multi-Awareness Network (CEMA-Net), which exploits the joint spectral–spatial–elevation features in depth to realize the accurate identification of land cover categories. Specifically, we propose a novel multi-way feature retention (MFR) module that explores deep spectral–spatial–elevation semantic information in the data through multiple paths. In addition, we propose spectral–spatial-aware enhancement (SAE) and elevation-aware enhancement (EAE) modules, which effectively enhance the awareness of ground objects that are sensitive to spectral and elevation information. Furthermore, to address the significant representation disparities and spatial misalignments between multi-source features, we propose a spectral–spatial–elevation feature calibration fusion (SFCF) module to efficiently integrate complementary characteristics from heterogeneous features. It incorporates two key advantages: (1) efficient learning of discriminative features from multi-source data, and (2) adaptive calibration of spatial differences. Comparative experimental results on the MUUFL, Trento, and Augsburg datasets demonstrate that CEMA-Net outperforms existing state-of-the-art methods, achieving superior classification accuracy with better feature map precision and minimal noise. Full article
(This article belongs to the Special Issue Advances in AI Technology for Remote Sensing Image Processing)
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20 pages, 7294 KiB  
Article
Prelaunch Reflective Solar Band Radiometric Performance of JPSS-3 and -4 VIIRS
by Amit Angal, David Moyer, Xiaoxiong Xiong, Qiang Ji and Daniel Link
Remote Sens. 2024, 16(24), 4799; https://doi.org/10.3390/rs16244799 - 23 Dec 2024
Viewed by 336
Abstract
The Joint Polar Satellite System 3 (JPSS-3) and -4 (JPSS-4) Visible Infrared Imaging Radiometer Suite (VIIRS) instruments are the last in the series (S-NPP VIIRS launched in October 2011, JPSS-1 VIIRS launched in November 2017, and JPSS-2 VIIRS launched in November 2022) of [...] Read more.
The Joint Polar Satellite System 3 (JPSS-3) and -4 (JPSS-4) Visible Infrared Imaging Radiometer Suite (VIIRS) instruments are the last in the series (S-NPP VIIRS launched in October 2011, JPSS-1 VIIRS launched in November 2017, and JPSS-2 VIIRS launched in November 2022) of highly advanced polar-orbiting environmental satellites. Both instruments underwent a comprehensive sensor-level thermal vacuum (TVAC) testing at the Raytheon Technologies El Segundo facility to characterize the spatial, spectral, and radiometric aspects of the VIIRS sensor performance. This paper focuses on the radiometric performance of the 14 reflective solar bands (RSBs) that cover the wavelength range from 0.41 to 2.3 µm. Key instrument calibration parameters such as instrument gain, signal-to-noise ratio (SNR), dynamic range, and radiometric calibration uncertainty were derived from the TVAC measurements for both the primary and redundant electronics at three instrument temperature plateaus: cold, nominal, and hot. This paper shows that all the JPSS-3 and -4 VIIRS RSB detectors have been well characterized, with key performance metrics comparable to the previous VIIRS instruments on-orbit. The radiometric calibration uncertainty of the RSBs is within the 2% requirement, except in the case of band M1 of JPSS-4. Comparison of the radiometric performance to sensor requirements, as well as a summary of key instrument testing and performance issues, is also presented. Full article
(This article belongs to the Collection The VIIRS Collection: Calibration, Validation, and Application)
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15 pages, 3329 KiB  
Article
The Effect of Thigh Muscle Forces on Knee Contact Force in Female Patients with Severe Knee Osteoarthritis
by Tingting Liu, Hao Xie, Songhua Yan, Jizhou Zeng and Kuan Zhang
Bioengineering 2024, 11(12), 1299; https://doi.org/10.3390/bioengineering11121299 - 20 Dec 2024
Viewed by 516
Abstract
Thigh muscles greatly influence knee joint loading, and abnormal loading significantly contributes to the progression of knee osteoarthritis (KOA). Muscle weakness in KOA patients is common, but the specific contribution of each thigh muscle to joint loading is unclear. The gait data from [...] Read more.
Thigh muscles greatly influence knee joint loading, and abnormal loading significantly contributes to the progression of knee osteoarthritis (KOA). Muscle weakness in KOA patients is common, but the specific contribution of each thigh muscle to joint loading is unclear. The gait data from 10 severe female KOA patients and 10 controls were collected, and the maximum isometric forces of the biceps femoris long head (BFL), semitendinosus (ST), rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) were calibrated via ultrasound. Four musculoskeletal (MSK) models were developed based on EMG-assisted optimization, static optimization, and ultrasound data. The ultrasound-calibrated EMG-assisted MSK model achieved higher accuracy (R2 > 0.97, RMSE < 0.045 Nm/kg). Patients exhibited increased VL and VM forces (p < 0.004) and decreased RF force (p < 0.006), along with elevated medial and total joint contact forces (p < 0.001) and reduced lateral forces (p < 0.001) compared to controls. The affected side relied on VL and BFL the most (p < 0.042), while RF was key for the unaffected side (p < 0.003). Ultrasound calibration and EMG-assisted optimization significantly enhanced MSK model accuracy. Patients exerted greater quadriceps and hamstring forces bilaterally, shifting knee loading medially, and depended more on the lateral thigh muscles on the affected side. Hamstrings contributed more to joint contact forces, while quadriceps’ contributions decreased. Full article
(This article belongs to the Special Issue Joint Biomechanics and Implant Design)
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21 pages, 10204 KiB  
Article
Numerical Modeling of Engineering-Scale Jointed Coal Mass and Confining Pressure Effect
by Feiteng Zhang, Xiangyu Wang, Qingcang Wang, Jianbiao Bai, Dingchao Chen, Menglong Li and Shiqi Sun
Appl. Sci. 2024, 14(24), 11844; https://doi.org/10.3390/app142411844 - 18 Dec 2024
Viewed by 525
Abstract
In coal masses, joints serve as crucial components influencing mechanical responses and failure mechanisms. The joint distribution complicates the acquisition of physical parameters for engineering-scale coal masses, and traditional laboratory or in situ tests often suffer from inaccuracies and high costs. Therefore, examination [...] Read more.
In coal masses, joints serve as crucial components influencing mechanical responses and failure mechanisms. The joint distribution complicates the acquisition of physical parameters for engineering-scale coal masses, and traditional laboratory or in situ tests often suffer from inaccuracies and high costs. Therefore, examination of the dynamic properties of engineering-scale coal mass is generally performed by numerical simulations. This paper proposes a model construction approach using two-dimension Particle Flow Code (PFC2D) software to study the mechanical properties of engineering-scale jointed coal mass, addressing the limitations of conventional models by integrating scale effects, accuracy, and computational efficiency. Firstly, the distribution characteristics and mechanical parameters of the joints in the coal mass were obtained based on field statistics and laboratory experiments. The parameters of the laboratory-scale model were calibrated by the numerical matching method. The discrete element model for the engineering-scale coal mass was constructed by the step-by-step matching method. The confining pressure effect on the coal mass under a biaxial loading condition was studied, while the strength change, fissure evolution, and failure mechanism under different confining pressures and fissure degrees were investigated. Based on the simulation results, a quantitative relationship was established between the mechanical parameters, fissure degree, and confining pressure under compression conditions. Ultimately, the failure zone ahead of the working face and the distribution of the abutment pressure were assessed using the mechanics parameters of coal masses with diverse joint distributions. Full article
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21 pages, 9617 KiB  
Article
A Robot Error Prediction and Compensation Method Using Joint Weights Optimization Within Configuration Space
by Fantong Meng, Jinhua Wei, Qianyi Feng, Zhigang Dong, Renke Kang, Dongming Guo and Jiankun Yang
Appl. Sci. 2024, 14(24), 11682; https://doi.org/10.3390/app142411682 - 14 Dec 2024
Viewed by 474
Abstract
With the growing demand for industrial robots in the aerospace manufacturing process, the lack of positioning accuracy has become a critical factor limiting their broad application in precision manufacturing. To enhance robot positioning accuracy, one crucial approach is to analyze the distribution patterns [...] Read more.
With the growing demand for industrial robots in the aerospace manufacturing process, the lack of positioning accuracy has become a critical factor limiting their broad application in precision manufacturing. To enhance robot positioning accuracy, one crucial approach is to analyze the distribution patterns of robot errors and leverage spatial similarity for error prediction and compensation. However, existing methods in Cartesian space struggle to achieve accurate error estimation when the robot is loaded or the end-effector orientations are varied. To address these challenges, a novel method for robot error prediction and accuracy compensation within configuration space is proposed. The analysis of robot error distribution reveals that the spatial similarity of robot errors is more pronounced and stable in configuration space compared to Cartesian space, and this property exhibits significant anisotropy across joint dimensions. A spatial-interpolation-based unbiased estimation method with joint weights optimization is proposed for robot errors prediction, and the particle filter method is utilized to search for the optimal joint weights, enhancing the anisotropic characteristics of the prediction model. Based on the robot error prediction model, a cyclic searching method is employed to directly compensate for the joint angles. An experimental system is established using an industrial robot equipped with a 120 kg end-effector and a laser tracker. Eighty sampling points with diverse poses are randomly selected within the task workspace to measure the robot errors before and after compensation. The proposed method achieves an error prediction accuracy of 0.172 mm, reducing the robot error from the original 4.96 mm to 0.28 mm, thus meeting the stringent accuracy requirements for hole machining in robotic aerospace assembly processes. Full article
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22 pages, 5444 KiB  
Article
Pre-Launch Thermal Emissive Band Radiometric Performance for JPSS-3 and -4 VIIRS
by David Moyer, Amit Angal, Jeff McIntire and Xiaoxiong Xiong
Remote Sens. 2024, 16(24), 4630; https://doi.org/10.3390/rs16244630 - 11 Dec 2024
Viewed by 581
Abstract
The Joint Polar Satellite System 3 (JPSS-3) and 4 (JPSS-4) Visible Infrared Imaging Radiometer Suite (VIIRS) are the fourth and fifth in its series of instruments designed to provide high-quality data products for environmental and climate data records. The VIIRS instrument must be [...] Read more.
The Joint Polar Satellite System 3 (JPSS-3) and 4 (JPSS-4) Visible Infrared Imaging Radiometer Suite (VIIRS) are the fourth and fifth in its series of instruments designed to provide high-quality data products for environmental and climate data records. The VIIRS instrument must be calibrated and characterized prior to launch to meet the data product needs. A comprehensive test program was conducted at the Raytheon Technologies facility in 2020 (JPSS-3) and 2023 (JPSS-4) that included extensive functional and environmental testing. The thermal band radiometric pre-launch performance and stability are the focus of this article, which also compares several instrument performance metrics to the design requirements. Brief comparisons with the JPSS-1 and -2 VIIRS instrument performance will also be discussed. Full article
(This article belongs to the Collection The VIIRS Collection: Calibration, Validation, and Application)
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12 pages, 3144 KiB  
Article
Is San Diego California on Track to Reach HCV Elimination? A Modeling Analysis of Combination Prevention Strategies
by Jaskaran S. Cheema, Scott Suckow, Christian Ramers, Patrick Loose, Andrea Tomada, Samantha Tweeten, Tara Stamos-Buesig, Daniela Abramovitz, William H. Eger, Steffanie A. Strathdee and Natasha K. Martin
Viruses 2024, 16(12), 1819; https://doi.org/10.3390/v16121819 - 22 Nov 2024
Cited by 1 | Viewed by 786
Abstract
In 2020, the Eliminate Hepatitis C Initiative in the county of San Diego (COSD) was launched, a private–public joint endeavor between the COSD and the American Liver Foundation. We use epidemic modeling to assess whether the COSD is on track to reach its [...] Read more.
In 2020, the Eliminate Hepatitis C Initiative in the county of San Diego (COSD) was launched, a private–public joint endeavor between the COSD and the American Liver Foundation. We use epidemic modeling to assess whether the COSD is on track to reach its elimination targets (80% reduction in incidence, 65% reduction in hepatitis C virus (HCV)-related mortality by 2030 compared to 2015) and what intervention scale-up may be required. We adapted a previously developed dynamic, deterministic model of HCV transmission and disease progression among adults in the COSD, stratified by risk, age, gender, and human immunodeficiency virus (HIV) status. The model is calibrated to detailed historical epidemiological data on HCV burden, treatment, and mortality in the COSD. We project HCV infections and mortality under status quo HCV treatment (65%/year among people coinfected with HCV and HIV, 0–5%/year among others) and determine what treatment scale-up among those without HIV is required to achieve HCV elimination, with or without concomitant reductions in injection transmission risk from 2024 onward. We project an increase in new HCV infections in the COSD to 2213 [95% C.I.: 1069–3763] in 2030, a mean 91% relative increase between 2015 and 2030. HCV-related deaths are expected to decrease to 246 [95% C.I.: 180–295] in 2030, a mean relative decrease of 14% compared to 2015. The incidence elimination target could be achieved through increasing HCV treatment among those without HIV to a mean of 60%/year, similar to the level achieved among people coinfected with HCV and HIV. Combination interventions reduce the treatment needed; if injecting risk is reduced by 25%, then treating 48%/year could achieve elimination. The COSD is likely not on track to reach the incidence or mortality targets, but achieving the incidence target is possible if treatment rates overall are scaled-up to rates that have been achieved among people coinfected with HCV and HIV. Elimination is achievable but requires committed funding and expansion of comprehensive testing, linkage, and treatment programs alongside harm reduction initiatives. Full article
(This article belongs to the Special Issue Hepatitis C Virus Infection among People Who Inject Drugs)
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17 pages, 8607 KiB  
Article
Numerical Study on Welding Residual Stress and Microstructure in Gas Metal Arc Welding Square Tube–Plate Y-Shaped Joints
by Zhaoru Yan and Jinsan Ju
Buildings 2024, 14(11), 3686; https://doi.org/10.3390/buildings14113686 - 19 Nov 2024
Viewed by 666
Abstract
Welding residual stresses significantly influence the mechanical behavior of hollow section joints, especially in the pivotal connection zones of steel structures employed in construction. The research object of this study is the Q355 steel square tube–plate Y-joint welded using Gas Metal Arc Welding [...] Read more.
Welding residual stresses significantly influence the mechanical behavior of hollow section joints, especially in the pivotal connection zones of steel structures employed in construction. The research object of this study is the Q355 steel square tube–plate Y-joint welded using Gas Metal Arc Welding (GMAW) with CO2 Shielding. The thermodynamic sequence coupling method was employed to simulate the temperature field, microstructure distribution, and welding residual stresses in square tube–plate Y-joints. Based on the monitored temperature field data and the cross-sectional dimensions of the weld pool, this study calibrated the finite element model. Subsequently, the calibrated finite element model was employed to analyze the influence of microstructural phase transformations and welding sequences on the welding residual stresses in square tube–plate Y-joints. The research findings indicate that the peak transverse welding residual stresses in the branch pipes of the four joint zones were lower when considering the phase transformation effect than when not accounting for it in the calculations. There was no significant difference in the transverse and longitudinal welding residual stresses on the surface of branch pipes under the three welding sequences. However, there were certain differences in the microstructural content of the weld zones under the three welding sequences, with the martensite content in the third welding sequence being significantly lower than that in the other two sequences. Full article
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13 pages, 5579 KiB  
Article
Small Punch Test to Estimate the Threshold Stress in Aggressive Environments by Incremental Step Loading
by Borja Arroyo, Laura Andrea, José A. Álvarez, Sergio Cicero, Federico Gutiérrez-Solana and Luis Abarca
Metals 2024, 14(11), 1234; https://doi.org/10.3390/met14111234 - 29 Oct 2024
Viewed by 564
Abstract
The present work is a relevant advance in the validation of the incremental step loading technique (ASTM F1624 standard) when applied to Small Punch tests (SPT) for the threshold load determination of medium- and high-strength steels in aggressive environments, as a novel alternative [...] Read more.
The present work is a relevant advance in the validation of the incremental step loading technique (ASTM F1624 standard) when applied to Small Punch tests (SPT) for the threshold load determination of medium- and high-strength steels in aggressive environments, as a novel alternative to conventional time-consuming tests under constant load. It completes previous works by the authors on this topic, extending a methodology to estimate the threshold stress from SPT tests in aggressive environments, covering the whole range of hardness marked by ASTM F1624 as the main goal. This is achieved by calibrating a model of the material’s hardness by the use of a coefficient in function of it. For this purpose, four medium- and high-strength steels of 33, 35, 50 and 60 HRC (Hardness Rockwell C) are exposed to three different cathodic polarization hydrogen embrittlement environments of 1, 5 and 10 mA/cm2 in 1N H2SO4 acid electrolyte connected to a platinum anode. Threshold stresses in these circumstances are obtained by uniaxial specimens following ASTM F1624 and compared to their homologous threshold loads obtained by Small Punch tests according to the authors’ original methodology proposal. Finally, the aforementioned model, consisting of a correlation based on composing an elastic and a plastic part, is calibrated for a hardness ranging 33–60 HRC, this being the main original contribution of this work; the elastic part is dependent just on the elastic-to-plastic transition SPT load, while the plastic part is ruled by a material hardness-dependent coefficient. This technique supposes an advance in engineering tools, due to its applicability in situations of material shortage, such as in-service components, welded joints, local areas, complex geometries, small thicknesses, etc., often present in aerospace, automotive or oil–gas, among others. Full article
(This article belongs to the Special Issue Fatigue, Creep Behavior and Fracture Mechanics of Metals)
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20 pages, 768 KiB  
Article
Partnering Implementation in SMEs: The Role of Trust
by Arvind Kumar Vidyarthy and Thyagaraj S. Kuthambalayan
Systems 2024, 12(10), 432; https://doi.org/10.3390/systems12100432 - 14 Oct 2024
Viewed by 895
Abstract
Resource Dependence Theory suggests that (a) power balance with resource interdependency, (b) formal/informal procedures for resource exchange, and (c) matching in goals and operational philosophies positively affect partnering implementation (information exchange and joint decision-making). Additionally, improved partnering implementation positive affects commitment fulfillment and [...] Read more.
Resource Dependence Theory suggests that (a) power balance with resource interdependency, (b) formal/informal procedures for resource exchange, and (c) matching in goals and operational philosophies positively affect partnering implementation (information exchange and joint decision-making). Additionally, improved partnering implementation positive affects commitment fulfillment and dispute resolution. In a setting where SMEs supply to small local retailers, the SMEs do not suffer from low bargaining power and rely on informal contracts, and both firms are compatible. The small trading partners in this study predominantly have face-to-face and telephonic interactions with each other (possible due to the small number). Knowledge of one another and a simple transaction process reduces risk and uncertainty, and leads to trust. In this study, trust is a contextual factor, and we aim to determine if there is a positive effect of (a), (b), and (c) on partnering implementation, and if the effect strengthens with an increase in the level of trust. Survey data are used to calibrate and validate a structural equation model independently. Through empirical research, we aim to identify deviations in results, determine the cause of deviation in the study characteristics, and add explanatory power to research findings. Except for the influence of trust on the positive relationship between informal procedures and partnering implementation, the finding fits with the theoretical bases. With a high level of trust, clarity in time, accuracy, and relevance of information exchanged may be lacking, compromising decision-making and adding to the ambiguity of partnering implementation with an informal agreement. Full article
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