Evidence on the association between dietary fiber intake and pancreatic cancer risk has been controversial. Therefore, we carried out this meta-analysis to summarize available evidence from epidemiologic studies on this point. Relevant studies were identified by searching PubMed, Embase and Web of Science databases as well as by reviewing the rence lists of relevant articles. Random or fixed-effects model was used to calculate the summary risk estimates and 95% confidence intervals (CIs). This meta-analysis included one cohort and thirteen case-control studies which involving a total of 3287 subjects with pancreatic cancer. After summarizing the risk estimates of these studies, we yielded a significant association between dietary fiber intake and pancreatic cancer risk among case-control studies (odds ratio = 0.54; 95%CI = 0.44–0.67; I2 = 41.4%; P = 0.043) but a non-significant result in cohort study (hazard ratio = 1.01; 95%CI = 0.59–1.74). Additionally, significant inverse associations were observed when we carried out the stratify analyses by the study characteristics and adjustment for potential confounders among case-control studies. Given only one cohort study included in the present meta-analysis, further prospective-designed studies should validate our findings and report more detail results, including those for subtypes of fiber, the risk estimates which corrected the impact of measurement errors and fully adjust for the potential confounders.
Summary
A semi‐active inerter‐based vibration isolator with semi‐active inerter is presented in this paper; the inertance of the semi‐active inerter is hierarchically adjusted between two values: the maximum inertance and minimum inertance. On the basis of the mechanical property of the semi‐active inerter, two acceleration–velocity‐based control strategies are proposed, which are the relative‐acceleration–relative‐velocity (RARV) control strategy and the relative‐acceleration–absolute‐velocity (RAAV) control strategy. The dynamic responses of the semi‐active inerter‐based vibration isolator with the two control strategies are obtained using the averaging method and further checked by the numerical results. Four performance indices are defined to evaluate the isolation performance of the semi‐active inerter‐based vibration isolator: maximum dynamic displacement, maximum transmissibility, isolation frequency band, and transmissibility in the higher isolation frequency band. The solving process to determine the four performance indices is investigated in detail in the paper. The results show that for the semi‐active inerter‐based vibration isolator, the maximum dynamic displacement and transmissibility are smaller than the passive one; the latter two performance indices fall in between the value when the maximum inertance and minimum inertance are achieved for the passive one. In addition, the isolation performance of the semi‐active inerter‐based vibration isolator with the two control strategies are compared based on the four performance indices.
Inerter, which is defined as a two-terminal mechanical element, has the characteristic that the force generated at its two terminals is proportional to the relative acceleration between its two ends. Here, the inerter is used in the vibration isolation system; eight kinds of one-stage inerter-based vibration isolators are presented in this paper. Dynamic equations of eight kinds of one-stage inerter-based vibration isolators are established, the natural frequency is considered, and the dynamic response and transmissibility are obtained using the time domain analysis method or the Laplace-transformed method. Four performance indexes are defined to evaluate their isolation performance and compared with the linear vibration isolator (LVI). The best structural parameters of these one-stage inerter-based vibration isolators are determined using the H[Formula: see text] optimization method based on the fixed-point theory, which aims to minimize the maximum transmissibility. The results show that compared with the LVI, some kinds of one-stage inerter-based vibration isolators can offer a better isolation performance according to the four performance indexes. Furthermore, the best vibration isolator among these vibration isolators is determined by the four performance indexes.
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