In this study, we experimentally demonstrate a class of lightweight acoustic metamaterial barriers that block low-frequency sound. The acoustic metamaterial barrier is composed of a thin rubber membrane coated over a stiff honeycomb plate. Our findings, combined with high-fidelity finite element simulations, demonstrate that the sound insulation performance of the acoustic metamaterial surpasses the mass law in three distinct frequency ranges: (a) the stiffness law dominates insulation up to 140 Hz, (b) degeneracy and destructive superposition of high-order natural modes dominate within the frequency range of 300–500 Hz, and (c) destructive interference between high-order resonance and membrane resonance dominates in the frequency range of 800–1200 Hz. Notably, our study highlights the potential of high-order shear vibration of the periodic structure for the resonant bending waves of the honeycomb cell that coincide with the wavelengths of longitudinal sound waves in air, thereby offering new design guidelines for lightweight acoustic metamaterial barriers. This study reports for the first time the coincidence of high-order and membrane resonance modes within the honeycomb cell by employing an accurate finite element model and experimental validation.
In this paper, we propose the seismic response analysis method and investigate the optimal design of the piping system supported by elasto-plastic damper subjected to the random input based on the random vibration theory. The piping system is modeled by simple cantilever beam with weight. The support force is given by bilinear model. The inputs are given by white Gaussian noises. In this optimal design, we can maintain the structural integrities of both the piping systems and the elasto-plastic supporting devices by taking three indexes; dynamic reliability of pipings, accumulated energy of support and dynamic reliability of support into account. Furthermore, the optimal conditions of parameters such as the supporting location, the capacity of the supporting devices are searched. Numerical simulations are performed using a simple piping system model for the random input based on the probabilistic vibration theory. The optimal design proposed here is applicable to the seismic design of piping systems supported by elasto-plastic dampers subjected to the actual earthquake input.
Background
A bridge to surgery (BTS) using self‐expandable metallic stents (SEMSs) is becoming the primary treatment for obstructive colorectal cancer (OCRC). In Japan, intestinal decompression was usually performed using decompression tubes (DTs). However, few reports have compared the outcomes of SEMS and DTs as BTS. Therefore, we compared the treatment outcomes of SEMS and DTs for OCRC.
Methods
Data of 80 patients who underwent radical resection after endoscopic decompression for stage II or III OCRC between 2007 and 2021 were retrospectively analyzed. Patients were divided into two groups based on whether they received SEMS (n = 53) or DTs (n = 27).
Results
The clinical success rate of decompression was 96.2% and 88.9% in the SEMS and DT groups, respectively. Additionally, 96.2% of patients who received SEMS were able to resume their routine diet without stricture symptoms. The rate of stoma construction and incidence of postoperative complications were lower in the SEMS group (p < 0.005 and p < 0.01, respectively). The 3‐year relapse‐free survival rates were 71.9% and 51.2% in the SEMS and DT groups, respectively, which were not significantly different (p = 0.10).
Conclusion
BTS using SEMS might be an adequate treatment for stage II or III OCRC regardless of tumor location owing to the comparable oncological outcomes with DT and low perioperative complication rate.
In this paper, we investigate the optimal design of the piping system supported by elasto-plastic damper subjected to the random input based on the random vibration theory. Using proposed optimal design, the structural integrity of both the piping systems and the elasto-plastic supporting devices are considered and the optimal conditions such as the supporting location, the capacity of the supporting devices are searched. Numerical simulations are performed using a simple piping system model for the white Gaussian noise input based on the random vibration theory.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.