Tuned mass damper (TMD) has a wide application in the human-induced vibration control of pedestrian bridges and its parameters have great influence on the control effects, hence it should be well designed. A new optimization method for a TMD system is proposed in this paper, based on the artificial fish swarm algorithm (AFSA), and the primary structural damping is taken into consideration. The optimization goal is to minimize the maximum dynamic amplification factor of the primary structure under external harmonic excitations. As a result, the optimized TMD has a smaller maximum dynamic amplification factor and better robustness. The optimum TMD parameters for a damped primary structure with different damping ratios and different TMD mass ratios are summarized in a table for simple, practical design, and the fitting equation is also provided. The TMD configuration optimized by the proposed method was shown to be superior to that optimized by other classical optimization methods. Finally, the application of an optimized TMD based on AFSA for a pedestrian bridge is proposed as a case study. The results show that the TMD designed based on AFSA has a smaller maximum dynamic amplification factor than the TMD designed based on the classic Den Hartog method and the TMD designed based on the Ioi Toshihiro method, and the optimized TMD has a good effect in controlling human-induced vibrations at different frequencies.

Background: The prevalence of nontuberculous mycobacterial lung disease (NTMLD) in the United States (US) has increased; however, data characterizing the associated healthcare utilization and expenditure at the national level are limited. Objective: To examine associations between economic outcomes and the use of anti-Mycobacterium avium complex (MAC) guidelines-based treatment (GBT) for newly diagnosed NTMLD in a US national managed care claims database (Optum® Clinformatics^® Data Mart). Methods: NTMLD was defined as having ≥2 claims for NTMLD (ICD-9 031.0; ICD-10 A31.0) on separate occasions ≥30 days apart (between 2007 and 2016). The cohort included patients insured continuously over a period of at least 36 months (12 months before initial NTMLD diagnostic claim and for the subsequent 24 months). Treatment was classified as GBT (consistent with American Thoracic Society/Infectious Diseases Society of America guidelines), non-GBT, or untreated. All-cause hospitalization rates and total healthcare expenditures at Year 2 were assessed as outcomes of the treatment prescribed in Year 1 after NTMLD diagnosis. Results: A total of 1039 patients met study criteria for NTMLD (GBT, n = 294; non-GBT, n = 298; untreated, n = 447). After adjustment for baseline characteristics, GBT was associated with a significantly lower all-cause hospitalization risk versus non-GBT (odds ratio [OR] = 0.53; 95% CI, 0.33-0.85, P = 0.008), and versus being untreated (OR =0.57; 95% CI, 0.35-0.91, P = 0.020). Adjusted total healthcare expenditure in Year 2 with GBT ($69,691) was lower than that with non-GBT ($77,624) with a difference of −$7933 (95% CI, −$14,968 to −$899; P = 0.03). Conclusions: Patients with NTMLD in a US managed claims database who were prescribed GBT had lower hospitalization risk than those who were prescribed non-GBT or were untreated. GBT was associated with lower total healthcare expenditure compared with non-GBT.

Under human-induced excitations, a floor structure may suffer excessive vibrations due to its large span and low damping ratio. Vertical vibrations, in particular, can become intolerable during resonance events. A tuned mass damper (TMD) is a widely used single-degree-of-freedom dynamic vibration absorber. To enhance the serviceability of a floor structure, a multiple TMD (MTMD) system finds broad application. The parameters of the MTMD must be carefully designed to achieve satisfactory performance. However, existing studies often employ a simplified model of the floor structure with closely spaced modes to optimize the parameters of MTMD. Nonetheless, an oversimplified floor model can lead to a reduction in its control effect. To solve this problem, this study utilizes the OAPI facility of SAP2000 to build a connection with MATLAB. A multi-objective optimization algorithm based on the artificial fish swarm algorithm (AFSA) for MTMD is developed in MATLAB, while the finite element model of a real floor structure is built in SAP2000. The locations of the MTMD system are initially specified in SAP2000 and, through the proposed MATLAB–SAP2000 interface, data can be exchanged between them. Based on the structural dynamic responses to external excitations in SAP2000, the optimization process for the MTMD is carried out in MATLAB. Concurrently, the parameters of the MTMD in SAP2000 are iteratively adjusted until they reach their final optimal values. To underscore the enhancements brought about by the proposed interface and optimization method, a comparative case study is conducted. A group of MTMDs, optimized using a conventional method, is presented for reference. The numerical results indicate that, overall, the proposed MTMD system exhibits superior control effectiveness and robustness.

Near-fault pulse motions will cause excessive and much larger base displacement in traditional isolated structures than common earthquake motions. The new isolation system inspired by the “sacrificial bonds and hidden length” biomechanics of an abalone shell can control the base displacement efficiently and reach almost the same vibration isolation efficiency as a semi-active control system. The current research is confined to the lumped mass model and cannot uncover the exact performance of isolators and structures in practical applications. A user subroutine is developed based on the interface of UEL in Abaqus. Subsequent verification has been done in both the lumped mass model and 3D complex model with Abaqus, Matlab/Simulink, and SAP2000. It can be revealed from the comparative results that the calculation accuracy of the secondary developed user subroutine can meet the demand of design and research.

Background: Individuals with mild cognitive impairment (MCI), a noticeable decline in cognitive abilities, are at increased risk of developing Alzheimer’s disease (AD) or other dementia. Risk factors for dementia, such as obesity, stroke, depression are highly prevalent among U.S. veterans We report on the trends in the prevalence of MCI using clinical notes over the past 5 years in the Veteran Affairs, the largest integrated healthcare system in the U.S.Method: Prevalent cases of MCI were identified from VA clinical notes for all Veterans aged 50 years and older in VA care from fiscal years (FYs) 2015‐19. VA clinical notes are maintained in searchable text integration utility files (TIU) available in the VA Corporate Data Warehouse (CDW). Pharmacy clinical notes were excluded. “Mild cognitive impairment” keyword was searched in clinical notes to identify patients with MCI. We validated the keyword “mild cognitive impairment” in 199 clinical notes. The positive predictive value for this validation was approximately 91%. For each FY, age and sex adjusted rates directly standardized to the 2010 U.S. Census general population were estimated.Result: A total of 308,930 prevalent cases of MCI were identified from VA clinical notes from FYs 2015‐19. Standardized prevalence rates for MCI increased steeply, with prevalence of 0.9% in FY 2015, increasing to 1.31% in FY 2019. Standardized age adjusted MCI prevalence rates also increased sharply for male (0.77% in FY 2015 to 1.10% in FY 2019) and female veterans (1.01% in FY 2015 to 1.50% in FY 2019) with rates higher for females than males for each FY.Conclusion: We observed recent trends of increasing prevalence rates for MCI among veterans identified from VA clinical notes. Considering the increased risk of dementia among individuals with MCI, our study finding of increasing prevalence of MCI among veterans highlights the critical need for effective interventions and treatment to target veterans with MCI.