Average austenite grain size evolution simulation during multi-pass shape metal hot rolling process

783-788Constitutive equations describing the flow stress of Q235 steel undergoing hot plastic deformation have been developed by integrating the microstructure models and exponential flow stress models presented in literatures, in which the microstructure models parameters have been re-determined based on the related experiments carried out on cylindrical specimens of the Q235 steel. Therefore, the integrated constitutive equations are capable of calculating the evolution of austenite grain size and investigating the effects of average austenite grain size on the flow stress of Q235 steel during hot deformation. A three-dimensional thermo-mechanically coupled FEM simulation of an 11-pass H-shape metal roughing rolling process with the austenite grain size evolution taken into account have been carried out to verify the rationality of roll pass schedule. The accuracy of the integrated constitutive equations has been preliminary validated by the comparisons between measured and the calculated values of rolling force

Average austenite grain size evolution simulation during multi-pass shape metal hot rolling process

Constitutive equations describing the flow stress of Q235 steel undergoing hot plastic deformation have been developed by integrating the microstructure models and exponential flow stress models presented in literatures, in which the microstructure models parameters have been re-determined based on the related experiments carried out on cylindrical specimens of the Q235 steel. Therefore, the integrated constitutive equations are capable of calculating the evolution of austenite grain size and investigating the effects of average austenite grain size on the flow stress of Q235 steel during hot deformation. A three-dimensional thermo-mechanically coupled FEM simulation of an 11-pass H-shape metal roughing rolling process with the austenite grain size evolution taken into account have been carried out to verify the rationality of roll pass schedule. The accuracy of the integrated constitutive equations has been preliminary validated by the comparisons between measured and the calculated values of rolling force

The abcc6a Gene Expression Is Required for Normal Zebrafish Development

Pseudoxanthoma elasticum (PXE) is caused by mutations in the ABCC6 gene, which encodes a putative efflux transporter, ABCC6. The zebrafish (Danio rerio) has two ABCC6-related sequences. To study the function of abcc6 during zebrafish development, the mRNA expression levels were measured using RT-PCR and in situ hybridization. The abcc6a showed a relatively high level of expression at 5 days post-fertilization (d.p.f.) and the expression was specific to the Kupffer's vesicles. The abcc6b expression was evident at 6hours post-fertilization (h.p.f.) and remained high up to 8 d.p.f., corresponding to embryonic kidney proximal tubules. Morpholinos were designed to both genes to prevent pre-mRNA splicing and block translation. Injection of the abcc6a morpholinos into 1–4 cell zebrafish embryos decreased gene expression by 54–81%, and induced a phenotype, pericardial edema and curled tail associated with death at around 8 d.p.f. Microinjecting zebrafish embryos with full-length mouse Abcc6 mRNA together with the morpholino completely rescued this phenotype. No phenotypic changes were observed when the abcc6b gene morpholino was injected into embryos with knock-down efficiency of 100%. These results suggest that abcc6a is an essential gene for normal zebrafish development and provide insight into the function of ABCC6, the gene mutated in PXE

The correction of instrument transformer ferroresonance model in IEC standard and study on resonance interval based on transformer damping

The traditional ferromagnetic resonance model of the inductive voltage transformer in the IEC/TR 61869-102 transformer standard ignores the DC resistance of the transformer. The author believes that ignoring the damping effect of the transformer itself is not justified. Based on this, the model is modified, and the corresponding differential equation is derived. Through simulation and field testing, it is found that the DC resistance of the transformer has a damping effect on resonant overvoltage and resonant overcurrent. Moreover, with an increase in DC resistance, the ferromagnetic resonance region decreases. By increasing the DC resistance of the voltage transformer, it helps to reduce the ferromagnetic resonance interval as well as the inrush current

Fracture Behavior of Permeable Asphalt Mixtures with Steel Slag under Low Temperature Based on Acoustic Emission Technique

Acoustic emission (AE), as a nondestructive testing (NDT) and real-time monitoring technique, could characterize the damage evolution and fracture behavior of materials. The primary objective of this paper was to investigate the improvement mechanism of steel slag on the low-temperature fracture behavior of permeable asphalt mixtures (PAM). Firstly, steel slag coarse aggregates were used to replace basalt coarse aggregates with equal volume at different levels (0%, 25%, 50%, 75%, and 100%). Then, the low-temperature splitting test with slow loading was used to obtain steady crack growth, and the crack initiation and propagation of specimens were monitored by AE technique in real time. From the low-temperature splitting test results, SS-100 (permeable asphalt mixtures with 100% steel slag) has the optimal low-temperature cracking resistance. Therefore, the difference of fracture behavior between the control group (permeable asphalt mixtures without steel slag) and SS-100 was mainly discussed. From the AE test results, a slight bottom-up trend of sentinel function was founded in the 0.6–0.9 displacement level for SS-100, which is different from the control group. Furthermore, the fracture stages of the control group and SS-100 could be divided based on cumulative RA and cumulative AF curves. The incorporation of 100% steel slag reduced the shear events and restrained the growth of shear cracking of the specimen in the macro-crack stage. Finally, the considerable drops of three kinds of b-values in the final phase were found in the control group, but significant repeated fluctuations in SS-100. In short, the fracture behavior of PAM under low temperature was significantly improved after adding 100% steel slag

Abscisic acid perception and signaling transduction in strawberry: A model for non-climacteric fruit ripening

On basis of fruit differential respiration and ethylene effects, climacteric and non-climacteric fruits have been classically defined. Over the past decades, the molecular mechanisms of climacteric fruit ripening were abundantly described and found to focus on ethylene perception and signaling transduction. In contrast, until our most recent breakthroughs, much progress has been made toward understanding the signaling perception and transduction mechanisms for abscisic acid (ABA) in strawberry, a model for non-climacteric fruit ripening. Our reports not only have provided several lines of strong evidences for ABA-regulated ripening of strawberry fruit, but also have demonstrated that homology proteins of Arabidopsis ABA receptors, including PYR/PYL/RCAR and ABAR/CHLH, act as positive regulators of ripening in response to ABA. These receptors also trigger a set of ABA downstream signaling components, and determine significant changes in the expression levels of both sugar and pigment metabolism-related genes that are closely associated with ripening. Soluble sugars, especially sucrose, may act as a signal molecular to trigger ABA accumulation through an enzymatic action of 9-cis-epoxycarotenoid dioxygenase 1 (FaNCED1). This mini-review offers an overview of these processes and also outlines the possible, molecular mechanisms for ABA in the regulation of strawberry fruit ripening through the ABA receptors