Detection and localization of closely distributed damages via lamb wave sparse reconstruction

Ultrasonic Lamb wave is a promising tool for structural health monitoring and nondestructive evaluation of plate-like structures. Using an array with several piezoelectric discs for damage imaging (i.e. visual detection and localization) is of interest. Commonly used delay-and-sum method is limited for overlapped signals when several damages are closely distributed in the structure. To overcome this limitation, modal-based sparse reconstruction imaging method is applied for adjacent damages in this study. Firstly, Lamb wave dispersion curve is obtained by solving the Rayleigh-Lamb equations. Subsequently, propagation modal of the damage-reflected signal is constructed based on the solved dispersion curve. Finally, the modal is used for damage imaging via sparse reconstruction and basis pursuit de-noising. Experimental data measured in an aluminum plate is considered, and the result demonstrates that the sparse reconstruction imaging method is effective to detect and localize closely distributed damages in the presence of signal overlapping

Exploring How Blockchain Impacts Loyalty Program Participation Behaviors: An Exploratory Case Study

How to keep customers motivated in participative behaviors remains one major challenge in extant loyalty program (LP) studies. While some companies have initiated efforts to utilize blockchain-based distributed ledgers and smart contract capabilities to enhance customer experience and improve LP efficiencies, academic assessment of blockchain application in the LP context remains scarce. This research attempts to establish a theoretical overview of how the key natures of blockchain influence customers’ varying motivations (economy, autonomy, competence and relatedness) and perceived value, which consequently induce participative behaviors in a loyalty points context. Then, using an exploratory case study of Bubichain in China, we verify that the blockchain-enabled loyalty points scheme not only improves customers’ economic perceived value by meeting their economic motives, as the traditional one does, but also enhances their social interaction and psychological self-fulfillment value perception by meeting their intrinsic motivations, thus increasing customers’ experience and participation behaviors

Vibration and post-buckling of a functionally graded beam subjected to non-conservative forces

Vibration and post-buckling of beams made from functionally graded materials (FGM) subjected to uniformly and tangentially compressing follower forces are studied in this paper. Based on the accurately and geometrically nonlinear theory for extensible beams, the dynamic governing equations for FGM beams under non-conservative load are formulated. By using a shooting method to solve the non-linearly differential equations numerically, the responses of post-buckling and free vibration in the vicinity of post-buckling configuration are obtained, in which the hinged-fixed boundary conditions of beam are considered. Effects of material gradient parameter on the critical buckling, post-buckling and lower frequencies of the FGM beam are discussed in details

Role of salivary anti-SSA/B antibodies for diagnosing primary Sjögren’s syndrome

The diagnosis of primary Sjögren’s syndrome (pSS) is complex, and the saliva test is a potential method to improve the existing diagnostic criteria. Objective: To estimate the diagnostic accuracy of salivary anti-SSA/B antibodies in primary Sjögren’s syndrome (pSS), and to analyze their correlations with clinical and laboratory profiles. Study Design: This study enrolled 100 pSS patients and 140 non-pSS controls, including 40 rheumatoid arthritis (RA) patients, 40 systemic lupus erythematosus (SLE) patients, and 60 healthy controls. Unstimulated whole saliva and stimulated parotid saliva samples were collected from the subjects. Salivary anti-SSA/B antibodies were measured using an enzyme-linked immunosorbent assay (ELISA). Clinical and laboratory data were retrieved from the medical records. Results: In the pSS group, the sensitivity of anti-SSA and anti-SSB antibodies in whole saliva was 49% and 29%, respectively, and the specificity was 87.5% and 95%. The sensitivity of anti-SSA and anti-SSB antibodies in parotid saliva was 32% and 8%, respectively, and the specificity was 95.52% and 97.86%, respectively. In the pSS group, the diagnostic accuracy of anti-SSA/B antibodies in whole saliva was significantly higher than in parotid saliva ( p <0.05), but was significantly lower than in serum ( p <0.05). The salivary flow rate in the pSS group posi - tive for whole salivary anti-SSA was significantly lower than in the negative group ( p <0.05). The prevalence of rheumatoid factor and antinuclear factor were significantly higher in salivary SSB-positive pSS patients than in SSB-negative patients ( p <0.05). Conclusions: Compared to parotid saliva, whole saliva is a more suitable diagnostic fluid. Using salivary anti- SSA/B antibodies as a single test item is insufficient given the relatively low sensitivity. Further studies should investigate the possibility of combining tests for different salivary autoantibodies as a method for diagnosing pSS