3,630 research outputs found
Novel inerter-based absorbers for suppressing beams vibration under successive moving loads
Inerter-based vibration absorbers are new generations of tuned mass dampers. The property of the inerter is that the relative acceleration between its two terminals is proportional to produced force. This paper proposes the use of inerter-based vibration absorbers for suppressing the beam vibration under successive moving loads. The vibrational system possesses continuous beam model accompanying by inerter-based vibration absorbers. The effectiveness of this new type of vibration absorber compared with the ordinary linear vibration absorber. The partial differential governing equation converts to a system of ordinary differential equations using the Bubnov–Galerkin method. The optimal parameters of the inerter-based vibration absorbers are presented. The results show that this novel vibration absorber can reduce vibration 37% more than the optimized classical linear vibration absorbers. Some results give quasi-beating response for the beam possesses inerter-based vibration absorbers
Nonlinear vibration of crowned gear pairs considering the effect of Hertzian contact stiffness
This study aims to analyze the influence of lead crowning modification of teeth on the vibration behavior of a spur gear pair. Two dynamic rotational models including an uncrowned and crowned gear are examined. Hertzian mesh stiffness is computed using tooth contact analysis in quasi-static state along a complete mesh cycle of teeth mesh. The dynamic orbits of the system are observed using some useful attractors which expand our understanding about the influence of crown modification on the vibration behavior of the gear pair. Nonlinear impact damper consists of non-integer compliance exponents identify energy dissipation of the system beneath the surface layer. By augmenting tooth crown modification, the surface penetration increases and consequently normal pressure of the contact area becomes noticeable. Finally, the results show modification prevents gear pair to experience period doubling bifurcation as the numerical results proved. Using this new method in dynamic analysis of contact, broaden the new horizon in analyzing of the surface of bodies in contact
The Effect of Adiponectin on Osteonectin Gene Expression by Oxidized Low Density Lipoprotein-Treated Vascular Smooth Muscle Cells
Osteonectin is a bone-associated protein involved in vascular calcification. Adiponectin may protect against cardiovascular disease but possible effects on vascular calcification have been poorly studied. The aim of this study was to investigate the modulatory effect of adiponectin on oxidized low density lipoprotein (oxLDL)-induced expression of osteonectin in human aorta vascular smooth muscle cells (HA/VSMCs). HA/VSMCs were cultured in F12K media and then treated with oxLDL (100 mu g/mL) in the presence or absence of adoponectin (5 mu g/mL) for 24 and 48 hours. mRNA expression and protein level of osteonectin were determined by quantitative real-time PCR and western blot analysis, respectively. After exposure to oxLDL, osteonectin expression increased 1.62 +/- 0.23- and 6.62 +/- 0.48-fold after 24 and 48 hours respectively compared to the control. Adiponectin increased oxLDL-induced osteonectin expression in a time-dependent manner after 24 and 48 hours (3.24 +/- 0.39- and 24.93 +/- 2.15-fold, respectively). Western blotting confirmed that osteonectin protein was upregulated by adiponectin. Our data suggest that OxLDL might cause the increase of osteonectin expression both at mRNA and protein level. This upregulation is intensified by adiponectin
Nonlinear vibration of the spiral bevel gear under periodic torque considering multiple elastic deformation evaluations due to different bearing supports
This paper investigates two parameters effect on vibrational responses of the spiral bevel gear. Changing the gear system overall stiffness (GSOS) considering elastic deformation and periodic torques are the two parameters which are represented as the main goals of this study. In order to investigate the effects of shaft stiffness and elastic deformation, two different cases with different support locations are considered. The first case is presented by locating the support close to the gear, and in the latter one, the distance between gear and support is increased. Besides, to study the effect of torque, two main types are considered: constant and periodic excitation torque. To illustrate the dynamic behavior, the governing differential equations are solved numerically according to the Runge-Kutta method. The equations are nonlinear due to backlash and time-varying coefficients as the results of GSOS variation. Vibrational phenomena are illustrated by means of bifurcation diagrams, RMS, and Poincare maps. Particular vibrational behaviors such as "chaos" and "period-doubling" phenomena are illustrated with details. By investigating the effect of shaft stiffness, results show that when the support is far away from gear, the vibration response increased by 67.5%. Moreover, while the input torque is constant, the support movement does not cause undesirable responses such as chaotic or period-doubling responses. The periodic torque causes undesirable responses such as chaos and bifurcation and period-doubling responses
On the Representation Theory of Orthofermions and Orthosupersymmetric Realization of Parasupersymmetry and Fractional Supersymmetry
We construct a canonical irreducible representation for the orthofermion
algebra of arbitrary order, and show that every representation decomposes into
irreducible representations that are isomorphic to either the canonical
representation or the trivial representation. We use these results to show that
every orthosupersymmetric system of order has a parasupersymmetry of order
and a fractional supersymmetry of order .Comment: 13 pages, to appear in J. Phys. A: Math. Ge
Non-Simplified SUSY: Stau-Coannihilation at LHC and ILC
If new phenomena beyond the Standard Model will be discovered at the LHC, the
properties of the new particles could be determined with data from the
High-Luminosity LHC and from a future linear collider like the ILC. We discuss
the possible interplay between measurements at the two accelerators in a
concrete example, namely a full SUSY model which features a small stau_1-LSP
mass difference. Various channels have been studied using the Snowmass 2013
combined LHC detector implementation in the Delphes simulation package, as well
as simulations of the ILD detector concept from the Technical Design Report. We
investigate both the LHC and ILC capabilities for discovery, separation and
identification of various parts of the spectrum. While some parts would be
discovered at the LHC, there is substantial room for further discoveries at the
ILC. We finally highlight examples where the precise knowledge about the lower
part of the mass spectrum which could be acquired at the ILC would enable a
more in-depth analysis of the LHC data with respect to the heavier states.Comment: 42 pages, 18 figures, 12 table
The effect of age and clinical circumstances on the outcome of red blood cell transfusion in critically ill patients
Introduction: Whether red blood cell (RBC) transfusion is beneficial remains controversial. In both retrospective and prospective evaluations, transfusion has been associated with adverse, neutral, or protective effects. These varying results likely stem from a complex interplay between transfusion, patient characteristics, and clinical context. The objective was to test whether age, comorbidities, and clinical context modulate the effect of transfusion on survival. Methods: By using the multiparameter intelligent monitoring in intensive care II database (v. 2.6), a retrospective analysis of 9,809 critically ill patients, we evaluated the effect of RBC transfusion on 30-day and 1-year mortality. Propensity score modeling and logistic regression adjusted for known confounding and assessed the independent effect of transfusion on 30-day and 1-year mortality. Sensitivity analysis was performed by using 3,164 transfused and non-transfused pairs, matched according the previously validated propensity model for RBC transfusion. Results: RBC transfusion did not affect 30-day or 1-year mortality in the overall cohort. Patients younger than 55 years had increased odds of mortality (OR, 1.71; P < 0.01) with transfusion. Patients older than 75 years had lower odds of 30-day and 1-year mortality (OR, 0.70; P < 0.01) with transfusion. Transfusion was associated with worse outcome among patients undergoing cardiac surgery (OR, 2.1; P < 0.01). The propensity-matched population corroborated findings identified by regression adjustment. Conclusion: A complex relation exists between RBC transfusion and clinical outcome. Our results show that transfusion is associated with improved outcomes in some cohorts and worse outcome in others, depending on comorbidities and patient characteristics. As such, future investigations and clinical decisions evaluating the value of transfusion should account for variations in baseline characteristics and clinical context. Electronic supplementary material The online version of this article (doi:10.1186/s13054-014-0487-z) contains supplementary material, which is available to authorized users
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