Objective This study explores the relationship between nutritional status and oral health quality of life, the self-efficacy of older inpatients and the correlative factors. Methods In this study, the convenience sampling method was used to select 307 older inpatients in the southern section of the Renji Hospital affiliated to Shanghai Jiao Tong University School of Medicine from October to December 2020 as the main research participants. A mini nutritional assessment questionnaire was used to assess nutritional status, and the Chinese version of a geriatric oral health assessment index questionnaire was used to determine the oral health quality of life. Self-efficacy was assessed by a general self-efficacy scale questionnaire. Descriptive statistics were used to analyse data using the SPSS 22.0 software. Pearson correlation and multiple linear regression analysis were applied to explore the correlation between variables and factors concerned with nutritional status, respectively. Results The results of this study showed that the self-efficacy and oral health quality of life of older inpatients were at a moderate level. Among the patients, 263 had one or more tooth defects, and only 128 had oral restorations or wore dentures. The risk of malnutrition in hospitalised older patients was 37.1%, and the incidence of malnutrition was 13.4%. The risk factors of nutritional status of older patients were age, oral-related quality of life, prealbumin index, self-efficacy, chronic disease, monthly income and tooth defect (P < 0.05). Conclusion The incidence of malnutrition and malnutrition risk in hospitalised older patients is relatively high. The main associated factors include age, tooth defect, oral health quality of life, self-efficacy, chronic disease status and monthly income. Therefore, older inpatients, especially those with prosthodontic problems, should carry out nutritional assessments, intervention and graded management as soon as possible to improve their self-efficacy, improve their nutrition and health status and reduce the incidence of a poor prognosis.
Introduction To improve the low frequency isolation capability of vibration isolation system, a kind of electromagnetic quasi-zero-stiffness (QZS) vibration isolator was designed. Materials and methods The negative stiffness electromagnetic spring paralleled with the linear positive stiffness spring to achieve the state of QZS. The nonlinear dynamic model of vibration isolator was established. Through the combination of theoretical formula and simulation analysis, the electromagnetic force expression was obtained. The amplitude-frequency responsecharacteristics and force transmissibility was solved by harmonic balance method, and the effects of system parameters on amplitude - frequency characteristics and transmissibility was analyzed. Conclusion The results show that the new isolator has better performance than the linear system, and the decreased damping ratio and excitation amplitude make the effects of vibration isolation of system superior.
Line spectra chaotification is a principal method to weaken or eliminate the line spectra feature of submarines. However, this method is difficult to obtain chaos under the variable working conditions and small amplitudes. Furthermore, there are multistable attractors in the nonlinear vibration isolation system simultaneously. So, the quality of chaos highly depends on initial conditions and systematic parameters. In this study, the attractor entrainment control and line spectra chaotification of a nonlinear vibration isolation system on the flexible foundation have been studied by using the open-plus-nonlinear-closed-loop method. First, the dynamic equation of the nonlinear vibration isolation system on the flexible foundation was formulated, and its exhaustive bifurcation characteristics were analyzed. The regulations of global characteristics and coexistent attractors were found out. Second, the entrainments between the different attractors were carried out under the open-plus-nonlinear-closed-loop control, which can ensure the system always works in the lowest line spectra intensity and the best overall vibration isolation performance. Finally, an open-plus-nonlinear-closed-loop coupling method was used to achieve generalized chaotic synchronization between the driving system and the response system, which effectively obtained sustainable chaos even under variable working conditions and small amplitudes. Simulation results validate the feasibility and validity of the open-plus-nonlinear-closed-loop method, which achieves the dual goals of effective vibration isolation in the low frequency range and line spectra chaotification under variable working conditions.
The purpose of this study is to investigate the characteristics of vibration isolation system with a single degree-of-freedom (SDOF) and a two-degree-of-freedom (2DOF) respectively based on the high-static-low-dynamic-stiffness (HSLDS). This model consists of a simple configuration connecting a vertical spring and a pair of oblique springs. The restoring force of the isolation system is approximated to linear and cubic stiffness by applying the Maclaurin series expansion. The dynamic equations of the SDOF and 2DOF are established for the harmonic force excitation. The frequency-amplitude response equation of the SDOF is obtained by employing the harmonic balance method (HBM) and is demonstrated in the classical Runge-Kutta method. The solution stability is ensured by applying the Floquet theory. Effects on the frequency response curves (FRCs) for the damping ratio and excitation amplitude are explored and discussed. The force transmissibility (FT) is defined to evaluate the vibration suppression capability. Effects on the FT of the SDOF and 2DOF for the excitation amplitude, mass ratio, and damping ratio are investigated. An experimental investigation of the SDOF is carried out to evaluate the actual attenuation performance in comparison with the equivalent linear system (ELS). The simulation and experimental results show that the HSLDS system with harmonic force excitation demonstrates hardening stiffness with multi-valued solutions. The occurrence of jump phenomenon is observed and explained by the stiffness variation. The system response and resonance frequency are affected by the excitation amplitude and damping ratio. The HSLDS system outperforms the ELS in a low frequency range if an appropriate mass is mounted. It is excited by a proper force and owns a suitable damper, which offers a theoretical guidance for the design and application of a novel HSLDS isolator.
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