A modified constitutive model and hot compression instability behavior of Cu-Ag alloy

The hot compressive deformation behaviors of Cu-6wt.%Ag alloy were studied experimentally in the temperature range of 973.1123 K and the strain rate range of 0.01.10 s^-1.The stress increases and reaches the maximum value when the true strain is very small,and then the stress changes slowly and tends to be stable under the action of work hardening,dynamic recovery and recrystallization.The material parameters of the conventional Arrhenius constitutive model are only related to strain under different deformation conditions,and the prediction error is large,which cannot accurately characterize the hot deformation behavior of the alloy.To describe the hot deformation behavior of the alloy accurately,a modified constitutive model was established by considering the simultaneous influence of forming temperature,strain rate and strain.The results indicate that correlation coefficient(R)and the average absolute relative error(AARE)are 0.993 and 4.2%,respectively.The modified constitutive model can accurately describe the hot deformation behavior of Cu-6wt.%Ag alloy.

Micro-vibration Modeling and Verification of Shutter Mechanism of Survey Space Telescope

The scientific research mission of the Survey Space Telescope(also known as the China Space Station Telescope,CSST)imposes rigorous requirements on the observation precision.However,microvibrations generated by the shutter mechanism can seriously affect the performance of the highly precise and sensitive instruments onboard.This study presents a dynamic model and verifies its performance using experimental results.Indeed,a five-degreeof-freedom nonlinear dynamic model that considers all interference sources and bearing nonlinearity is established.The validity of the proposed model is verified using experimental measurements of the microvibration characteristics.The obtained results proved that the proposed dynamic model can accurately predict the characteristics of the microvibrations caused by the shutter mechanism in the design stage and provide a theoretical basis for the development of CSST.

Effect of repetitive transcranial magnetic stimulation combined with swallowing training on the nutritional status and neurological function of patients with dysphigin after stroke

Objective: To study the effect of repetitive transcranial magnetic stimulation combined with swallowing training on the nutritional status and neurological function of patients with dysphigin after stroke. Methods: Patients with dysphagia after stroke who received rehabilitation in Nanjing Brain Hospital between June 2014 and September 2016 were selected and randomly divided into magnetic stimulation + training group and training group who received repetitive transcranial magnetic stimulation combined with swallowing training and swallowing training alone respectively. The nutritional status indexes, nerve injury indexes and neurotrophy indexes in serum were determined before treatment and 28 d after treatment. Results: 28 d after treatment, serum ALB, Hb, PAB, TRF, IGF-1, BDNF, NGF and VEGF contents of both groups of patients were higher than those before treatment while VILIP-1, NSE, Fibulin-5, NPY and Nogo-A contents were lower than those before treatment, and serum ALB, Hb, PAB, TRF, IGF-1, BDNF, NGF and VEGF contents of magnetic stimulation+ training group were higher than those of training group while VILIP-1, NSE, Fibulin-5, NPY and Nogo-A contents were lower than those of training group. Conclusion: Repetitive transcranial magnetic stimulation combined with swallowing training for dysphigin after stroke can improve the nutritional status and improve the neurological function.

Effect of compression deformation on precipitation phase behavior of B-containing S31254 super austenitic stainless steel

Effects of compression deformation on the sigma-phase precipitation behavior of B-containing S31254 stainless steel after solution treatment were studied using the Gleeble compression test. The cold and hot processing characteristics of B-containing S31254 stainless steel were evaluated, and the results show that the speed of compression deformation increased the precipitation rate of the sigma phase, and the location of precipitation extended from the austenite grain boundary to the original hot rolling deformation area. During cold deformation at room temperature, the precipitation rate increased when the deformation reached at 40%. Deformation at 950℃ affected precipitation more obviously. At 1074 ℃, when the deformation reached 20%, the precipitated phases started increasing, and above this deformation range, precipitation began decreasing. Also, at 1074℃ the deformation accelerated the precipitation of sigma phase;but with deformation, there was a change in critical temperature for the sigma-phase excursion. The precipitation position of the sigma phase is strongly related to the area of the original hot rolling deformation. With an increase in the deformation amount, precipitates in this region appeared as coarse-grained, skeletal, and network-like features.

On-chip optical interconnect using visible light

We propose and fabricate a monolithic optical interconnect on a GaN-on-silicon platform using a wafer-level technique. Because the InGaN/GaN mukiple-quantum-well diodes （MQWDs） can achieve light emission and detection simultaneously, the emitter and collector sharing identical MQW structure are produced using the same process. Suspended waveguides interconnect the emitter with the collector to form in-plane light coupling. Monolithic optical interconnect chip integrates the emitter, waveguide, base, and collector into a multi-component system with a common base. Output states superposition and 1 × 2 in-piane light communication are experimentally demonstrated. The proposed monolithic optical interconnect opens a promising way toward the diverse applications from in-plane visible light communication to light-induced imaging, and optical sensing. artificial synaptic devices, intelligent display, on-chip