Rotational Friction Damper’s Performance for Controlling Seismic Response of High Speed Railway Bridge-Track System

CRTS-II slab ballastless track on bridge is a unique system in China high speed railway.The application of longitudinal continuous track system has obviously changed dynamic characteristics of bridge structure.The bridge system and CRTS-II track system form a complex nonlinear system.To investigate the seismic response of high speed railway(HSR)simply supported bridge-track system,nonlinear models of three-span simply supported bridge with piers of different height and CRTS-II slab ballastless track system are established.By seismic analysis,it is found that shear alveolar in CRTS-II track system is more prone to be damaged than bridge components,such as piers,girders and bearings.The result shows that the inconsistent displacement of bridge girders is the main cause of the CRTS-II track system’s damage.Then the rotational friction damper(RFD)is adopted,which utilizes the device’s rotation and friction to dissipate seismic energy.The hysteretic behavior of RFD is studied by numerical and experimental methods.Results prove that RFD can provide good hysteretic energy dissipation ability with stable performance.Furthermore,the analysis of RFD’s influence on seismic response of HSR bridge-track system shows that RFD with larger sliding force is more effective in controlling excessive inconsistent displacement where RFD is installed,though response of other bridge spans could slightly deteriorated.

cDNA-AFLP analysis reveals altered gene expression profiles involved in juice sac granulation in pummelo(Citrus grandis)

Citrus fruits produced in China are often affected by granulation.Granulation is an altered physiological state of citrus fruits occurring usually before harvest but whose underlying mechanisms remain elusive.In this study,cDNA-AFLP technology enabled the identification of 116 granulation-associated genes in pummelo(C.grandis)juice sacs.Differentially expressed transcript-derived fragments(TDFs)were shown to be mainly involved in biological regulation and signal transduction,carbohydrate and energy metabolism,nucleic acid,protein metabolism,stress responses,and cell metabolism.Therefore,granulation in pummelo juice sacs seems to involve the following alterations:(1)changes in hormone levels;(2)activation of metabolic pathways related to ATP and sugar synthesis to produce more energy;(3)nucleic acid accumulation and increased protein degradation;(4)activation of stress-responsive metabolic pathways;(5)accelerated juice sac senescence.Our findings provide an overview of differential responses occurring at the transcriptional level in granulated juice sacs,thus revealing new insights into the adaptive mechanisms underlying this altered physiological state in‘Guanximiyou'pummelo(C.grandis)juice sacs.