Recent developments in explosive welding

Explosion welding (EXW) is one of the joining methods consisting of a solid state welding process in which controlled explosive detonation on the surface of a metal. During the collision, a high velocity jet is produced to remove away the impurities on the metal surfaces. Flyer plate collides with base plate resulting in a bonding at the interface of metals. The metal plates are joined at an internal point under the influence of a very high pressure and causes considerable local plastic deformation at the interface in which metallurgical bonding occurs in nature and even stronger than the parent metals. Similar and dissimilar materials can be joined by explosive welding. In this paper, after detection the theories of welding and wave formation, experimental research and numerical studies on explosive welding are reviewed for the last four decades. Also, future developments in explosive welding are predicted and criticized in an outlook.     

Statistical Analysis and Multimodal Classification on Noisy Eye Tracker and Application Log Data of Children with Autism and ADHD

Emotion recognition behavior and performance may vary between people with major neurodevelopmental disorders such as Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD) and control groups. It is crucial to identify these differences for early diagnosis and individual treatment purposes. This study represents a methodology by using statistical data analysis and machine learning to provide help to psychiatrists and therapists on the diagnosis and individualized treatment of participants with ASD and ADHD. In this paper we propose an emotion recognition experiment environment and collect eye tracker fixation data together with the application log data (APL). In order to detect the diagnosis of the participant we used classification algorithms with the Tomek links noise removing method. The highest classification accuracy results were reported as 86.36% for ASD vs. Control, 81.82% for ADHD vs. Control and 70.83% for ASD vs. ADHD. This study provides evidence that fixation and APL data have distinguishing features for the diagnosis of ASD and ADHD.     

Investigation of explosive welding parameters and their effects on microhardness and shear strength

The aim of this study was to investigate the strength of explosive welded metals with the same chemical compositions. Different welding interfaces (straight, wavy and continuous solidified-melted) were used with changing explosive welding parameters [stand-off distance (s), explosive loading (R) and anvils]. Joined metals were investigated under heat-treated and untreated conditions. Results on the microstructure, microhardness, tensile shear strength and bending tests are reported. According to the experimental results, the effect of the anvil on the explosive welding process was only the joining or not-joining performance. It was shown that the bonding interface changed from a straight to a wavy structure when the explosive loading and stand-off distance were increased. For wavy interfaces, when the explosive loading was increased the wavy length and amplitude increased. Results of tensile shear and bending tests showed that heat-treated specimens have more strength than untreated samples. According to tensile shear test results, straight and wavy interfaces had similar strength. In addition, in bending tests of untreated specimens it was shown that the bending zone had some cracks.     

Tribological properties of some phenolic composites suggested for automotive brakes

Brake linings used in automotive disk brakes are usually made of various components such as phenolic resin, Cu powder, BaSO₄, Al₂O₃, etc. In this study, 20 specimens with different compositions of the components were manufactured and a pad-on-disc-type wear tester was used. Friction and wear characteristics of the specimens next to a disk made of cast iron were studied. In addition, micro-structural characterisation of braking pads was carried out using SEM and also the effect of temperature on behaviour of the pads was investigated at the temperatures of 50–400 °C and pressure of 1050 and 3000 kPa. Finally, the effect of environment on the pads was investigated in water, salty water, oil and braking liquid media.     

Helicobacter pylori and hypergastrinemia in children with recurrent abdominal pain

Recurrent abdominal pain (RAP) is a significant problem in the pediatric population, and there has been much recent interest in the role that Helicobacter pylori (Hp) might play in this disorder. In this case control study, the authors aimed to determine whether Hp is an agent responsible for RAP, and to assess fasting gastrin concentrations in children with and without RAP in the Hp-positive and -negative groups. The study was conducted in 42 patients with RAP and 50 healthy children attending routine day-case surgery as a control group, aged 3 to 15 years, over a 12-month period. Of the 42 children with RAP, 30 were seropositive (71.4%) for Hp IgG, and of 50 children in the control group, 32 were seropositive (64%) for Hp IgG (P > 0.05). We found that Hp infection was as high in healthy children as in children with RAP. The mean fasting gastrin levels in 62 Hp-seropositive children (60.4 ng/l) were not different from those in 30 Hp-seronegative children (57.3 ng/l) and those in 42 children with RAP (58.2 ng/l) were also not significantly different from those in 50 healthy children (62.9 ng/l). Thus, no association between childhood Hp infection, hypergastrinemia, and RAP was found in our Turkish population.