Search

A novel ultrasonic vibration enhanced friction stir welding (UVeFSW) process was employed to join the rolled 2195 aluminium-lithium alloy of 4 mm thickness. The effects of superimposing ultrasonic on the macro metallograph,microhardness and tensile properties of welded joints were compared and analyzed. The effect of process parameters on the weld formation and joint mechanical properties of aluminium-lithium alloy by ultrasonic vibration enhanced friction stir welding was investigated. The results show that under the same process parameters superimposing ultrasonic energy in friction stir welding can improve the formability of 2195 aluminium-lithium alloy and enhance the plastic material flow in the weld nugget zone, which can reduce or even eliminate the void defect in the conventional friction stir welding joint. The microhardness at the top and middle of the nugget zone increases due to the ultrasonic effect, while the bottom of the weld does not change much. The fracture surfaces of the joints show a ductile fracture mode, and the elongation of the joints increases after ultrasonic vibration energy is applied, and the fracture dimples are more fine and uniform. Under the welding parameters studied the maximum tensile strength and elongation of the joint are 282.8 MPa and 11.5%, respectively. Under the conditions with rotational speed of 600 r/min and welding rate of 225 mm/min, the application of ultrasound can improve the tensile strength and the elongation of the joint by 17.5 MPa and 3.7% respectively.

Objectives/hypothesis: This study aimed to evaluate the prevalence of peripheral vestibular disorders in an Asian population of predominantly Han Chinese ethnicity.Study Design: Cross-sectional study.Methods: Patients with a peripheral vertigo disorder were identified from the Taiwan Health Insurance Research Database, a database of all medical claims of a randomly selected, population-representative sample of 2 million enrollees of Taiwan's National Health Insurance system covering over 99% of Taiwan's citizens. In 2016, 59,986 patients received a diagnosis of peripheral vestibular disorders in Taiwan. We calculated the population-wide prevalence rates of peripheral vestibular disorders in 2016 by sex and age group (20 to 24, 25 to 29, 30 to 34, 35 to 39, 40 to 44, 45 to 49, 50 to 54, 55 to 59, 60 to 64, 65 to 69, and ≥ 70 years) stratified into five urbanization levels.Results: The prevalence rate of peripheral vestibular disorders was 2,833.4 per 100,000 population during the year. Prevalence of Meniere's disease was 70.4 per 100,000, benign paroxysmal positional vertigo, 446.4, vestibular neuritis 307.2, and other or unspecified peripheral vestibular dizziness, 2,009.5 per 100,000. Prevalence rates steadily increased with age for every type of peripheral vestibular disorder, and were higher among females compared to males. The female-to-male gender ratios were 1.84, 1.89, and 1.93 for Meniere's disease, vestibular neuritis, and other peripheral vestibular dizziness, respectively. Counties with the lowest urbanization level had the highest prevalence rates of all types of peripheral vestibular disorders except vestibular neuritis.Conclusions: Results showed that peripheral vestibular disorders are common in Taiwan, increase with age, are predominantly female, and show higher prevalence in rural areas.Level Of Evidence: 2b Laryngoscope, 131:639-643, 2021. [ABSTRACT FROM AUTHOR]