Search Results (7)

To enhance the improvement effect of Enzyme-Induced Carbonate Precipitation (EICP) technology more effectively, an abundant renewable resource—lignin—was introduced as an additive during the EICP modification process of silty clay. The mechanical properties of the improved soil specimens were analyzed from a macroscopic point of view by using unconsolidated undrained (UU) triaxial tests and unconfined compressive strength (UCS) tests to determine the optimal lignin content and curing time. The micro-mechanism of the improved soil specimens was elucidated from the microscopic point of view by combining scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. The experimental results showed that lignin synergized with EICP could effectively improve the mechanical properties of the soil, and the mechanical properties of the co-consolidated soil specimens were better than those of the single consolidated and untreated soil specimens as a whole. The single EICP-consolidated soil specimen had undergone brittle damage; lignin could enhance the toughness of the soil and weaken its brittle characteristics. With the increase of lignin content, the mechanical indicators of co-consolidated soil specimens showed the trend of increasing and then decreasing, and reached the optimum at 0.75%. Moreover, the addition of lignin significantly increased the cohesive force, while the friction angle was less affected. With extended curing time, the mechanical indicators of the co-consolidated soil specimens increased overall, and tended to stabilize after 7 days of curing, hence selecting 7 days as the optimal curing time. From the microscopic point of view, lignin provides nucleation sites for the calcium carbonate precipitates generated by EICP, and the joint action of the two can fill the soil pores and cement the soil particles, thereby improving the overall strength of the soil. The results of the study can provide a theoretical basis and practical reference for the construction of foundation projects in silty clay areas. Full article

Ultrasonic welding of fibre-reinforced thermoplastics is a joining technology with high potential for short welding times and low energy consumption. While the majority of the current studies on continuous ultrasonic welding have so far focused on woven reinforcements, unidirectional materials are preferred for highly loaded aerospace components due to their better mechanical performance. Therefore, this paper investigates the influence and interdependence of the welding speed, amplitude, and energy director thickness on the weld quality of adherends made of unidirectional composites. The quality of the welded joints is assessed by a single-lap shear strength and fracture surface analysis complemented by the microscopic analysis of cross-sections and comparison to a co-consolidated reference. The results showed that the welding process is highly affected by changing welding speeds for a given amplitude. Furthermore, while lower amplitudes lead to significant scatter in the welding quality, higher amplitudes result in increased heating rates and a fully molten energy director even for high welding speeds. Nevertheless, insufficient consolidation at high welding speeds results in porosity in the weld line. Finally, it was observed that thicker, and therefore more compliant, energy directors lead to more uniform melting of the energy director and less deviation in the weld quality for a wider range of welding speeds. Full article

The rapid evolution of coronaviruses in respiratory diseases, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses a significant challenge for deep learning models to accurately detect and adapt to new strains. To address this challenge, we propose a novel Continuous Learning approach, CoroTrans-CL, for the diagnosis and prevention of various coronavirus infections that cause severe respiratory diseases using chest radiography images. Our approach is based on the Swin Transformer architecture and uses a combination of the Elastic Weight Consolidation (EWC) and Herding Selection Replay (HSR) methods to mitigate the problem of catastrophic forgetting. We constructed an informative benchmark dataset containing multiple strains of coronaviruses and present the proposed approach in five successive learning stages representing the epidemic timeline of different coronaviruses (SARS, MERS, wild-type SARS-CoV-2, and the Omicron and Delta variants of SARS-CoV-2) in the real world. Our experiments showed that the proposed CoroTrans-CL model achieved a joint training accuracy of 95.34%, an F1 score of 92%, and an average accuracy of 83.40% while maintaining a balance between plasticity and stability. Our study demonstrates that CoroTrans-CL can accurately diagnose and detect the changes caused by new mutant viral strains in the lungs without forgetting existing strains, and it provides an effective solution for the ongoing diagnosis of mutant SARS-CoV-2 virus infections. Full article

In the present work, a numerical model based on the cohesive zone modeling (CZM) approach has been developed to simulate mixed-mode fracture of co-consolidated low melt polyaryletherketone thermoplastic laminates by considering fiber bridging. A modified traction separation law of a tri-linear form has been developed by superimposing the bi-linear behaviors of the matrix and fibers. Initially, the data from mode I (DCB) and mode II (ENF) fracture toughness tests were used to construct the R-curves of the joints in the opening and sliding directions. The constructed curves were incorporated into the numerical models employing a user-defined material subroutine developed in the LS-Dyna finite element (FE) code. A numerical method was used to extract the fiber bridging law directly from the simulation results, thus eliminating the need for the continuous monitoring of crack opening displacement during testing. The final cohesive model was implemented via two identical FE models to simulate the fracture of a Single-Lap-Shear specimen, in which a considerable amount of fiber bridging was observed on the fracture area. The numerical results showed that the developed model presented improved accuracy in comparison to the CZM with the bi-linear traction–separation law (T–SL) in terms of the predicted strength of the joint. Full article

This work presents a detailed investigation for the effect of Y₂O₃ and Ni additions on the densification behavior, microstructural evolution and mechanical properties of a WC-Co-TaC-NbC composite. With the aim of obtaining WC-based composites with improved fracture toughness, to be used in severe conditions of high-temperature deformation, different concentrations of Y₂O₃ were incorporated with and without 5 wt% Ni addition. The consolidated composites were characterized using density measurement, XRD, SEM, hardness, fracture toughness, transverse rupture strength and compression testing. Fully dense composites were obtained through the applied consolidation regime of cold compaction and sintering at 1450 °C for 1.5 h under vacuum with a relative density up to 97%. The addition of 2.5 wt% Y₂O₃ to the base WC composite increased the relative density and then slightly decreased with the increase of the Y₂O₃ content. The addition of 5 wt% Ni to the base composites significantly increased the relative density to 97%. The XRD results indicated the existence of the Co₃W₃C η-phase after sintering, and the intensity of its peaks was reduced with the addition of 5 wt% Ni. The microstructure of the consolidated composites consisted of three phases: WC, Co₃W₃C and Y₂O₃. The area fraction of the Y₂O₃ phase increased as its weight fraction increased. In terms of the fracture toughness, the transverse-rupture strength (TRS) and the compressive strength were significantly improved by the addition of 5 wt% Ni with the 2.5 wt% Y₂O₃. Accordingly, this composition was used to manufacture the tools for the friction stir welding of the high-softening-temperature materials, which was successfully used for 25 plunges and about 500 cm of butt joints in nickel-based and carbon–steel alloys. Full article

Previously, a consolidated mathematical model of primary tumor (PT) growth and secondary distant metastasis (sdMTS) growth in breast cancer (BC) (CoMPaS) was presented. The aim was to detect the diagnostic periods for visible sdMTS via CoMPaS in patients with different subtypes ER/PR/HER2/Ki-67 (Estrogen Receptor/Progesterone Receptor/Human Epidermal growth factor Receptor 2/Ki-67 marker) of breast cancer. CoMPaS is based on an exponential growth model and complementing formulas, and the model corresponds to the tumor-node-metastasis (TNM) staging system and BC subtypes (ER/PR/HER2/Ki-67). The CoMPaS model reflects (1) the subtypes of BC, such as ER/PR/HER2/Ki-67, and (2) the growth processes of the PT and sdMTSs in BC patients without or with lymph node metastases (MTSs) in accordance with the eighth edition American Joint Committee on Cancer prognostic staging system for breast cancer. CoMPaS correctly describes the growth of the PT in the ER/PR/HER2/Ki-67 subtypes of BC patients and helps to calculate the different diagnostic periods, depending on the tumor volume doubling time of sdMTS, when sdMTSs might appear. CoMPaS and the corresponding software tool can help (1) to start the early treatment of small sdMTSs in BC patients with different tumor subtypes (ER/PR/HER2/Ki-67), and (2) to consider the patient almost healthy if sdMTSs do not appear during the different diagnostic periods. Full article

There is a rising awareness of the power of the public sector in enhancing sustainable consumption and production practices, in particular related to food procurement and its social, ethical, economical and environmental implications. School meal services have a high resonance in the debate on collective catering services because of the implications on the education to sustainable dietary habits and the orientation of the production system. This contribution focuses on the reciprocal relationship between professionals and users of school meal services as a driver to mobilize new resources—according to the theory of co-production—that steer service innovation and a shift towards more sustainable practices. We illustrate this through a case study on the school meal system in Pisa (Italy), where the Canteen Committee represents an institutional arena for participation and empowerment of actors that has gradually gained a central role in shaping this school meal service. Despite the challenges and obstacles, the institutionalized co-production of services allows consolidation of trust among key players and the introduction of innovations in the service, in the form of several projects oriented to sustainability which would not take place without the joint effort of actors involved, parents in the first place. Full article