RESUMO
The use of thermoplastic composites (TPCs) as one of the lightweight solutions will inevitably encounter problems in connection. Resistance welding has the characteristics of high strength, simplicity, and high reliability, and is considered a very potential hot-melt connection technology. The resistance welding technology of unidirectional carbon fiber-reinforced polyphenylene sulfide composites (UCF/PPS) was systematically studied. The experimental results show that the 100-mesh brass mesh has the best resin wetting effect and heating efficiency, and the PPS/oxidized 100-mesh brass mesh composite resistance element (Ox-RE/PPS) has the highest welding strength. The welding failure mode changes from interface failure and RE failure to interlayer structure damage and fiber fracture. The single-factor experimental results show that the maximum welding strength is reached at 310 °C, 1.15 MPa, and 120 kW/m2. According to the conclusion of the single-factor experiment, the Box-Behnken method was further used to design a three-factor, three-level experiment, and a quadratic regression model was established according to the test results. The results of variance analysis, fitting curve analysis, and perturbation plot analysis proved that the model had high fitting and prediction abilities. From the 3D surface diagram analysis, the influence of power density is the largest, and the interaction between welding temperature and power density is the most significant. Combined with the analysis of Design Expert 13 software, the optimal range of process parameters was obtained as follows: welding temperature 313-314 °C, welding pressure 1.04-1.2 MPa, and power density 124-128 kW/m2. The average strength of resistance welding joints prepared in the optimal range of process parameters was 13.58 MPa.
RESUMO
AIM: To explore the feasibility of the application of the Automated Breast Volume Scanner (ABVS) ACUSON S2000 in the diagnosis of soft tissue tumors. METHODS: The data of handheld ultrasound (HHUS) scans and ABVS volume three-dimensional (3D) reconstruction were collected from 66 patients with soft tissue tumors. The diagnosis rates for the two methods were compared. Additionally, the sonographic features of the lesions on ABVS imaging were evaluated. The data of the sonographic "hyperechoic rim sign" and "heterogeneous texture sign" were analyzed for the differential diagnosis. RESULTS: Automatic 3D reconstruction and high-resolution images from the coronal and sagittal planes were obtained using the ABVS. Although the ABVS is similar to HHUS in terms of sensitivity (81.8% vs. 77.3%, respectively), specificity (93.2% vs. 88.6%, respectively), and accuracy (89.4% vs. 84.8%, respectively), the success rates for full view of the lesion and detection rates of multiple lesions are significantly improved by the ABVS. Furthermore, the "hyperechoic rim sign" can be regarded as a specific diagnostic factor for benign tumors, with a diagnostic specificity and a positive predictive value of 86.4% and 91.4%, respectively. Additionally, the "heterogeneous texture" appeared commonly in malignant tumors, with a diagnostic sensitivity and a negative predictive value of 81.8% and 87.5%, respectively. CONCLUSION: Compared with conventional two-dimensional imaging, automatic 3D reconstruction and high-resolution images from three vertical planes can be displayed by the ABVS, and the global anatomy and surrounding tissue of the lesions can be clearly presented. Thus, ABVS imaging may help to differentiate between benign and malignant soft tissue tumors.