Achieving High Strength and Tensile Ductility in Pure Nickel by Cryorolling with Subsequent Low-Temperature Short-Time Annealing

Ultra fine-grained pure metals and their alloys have high strength and low ductility.In this study,cryorolling under different strains followed by low-temperature short-time annealing was used to fabricate pure nickel sheets combining high strength with good ductility.The results show that,for different cryorolling strains,the uniform elongation was greatly increased without sacrificing the strength after annealing.A yield strength of 607 MPa and a uniform elongation of 11.7%were obtained after annealing at a small cryorolling strain(ε=0.22),while annealing at a large cryorolling strain(ε=1.6)resulted in a yield strength of 990 MPa and a uniform elongation of 6.4%.X-ray diffraction(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM),and electron backscattered diffraction(EBSD)were used to characterize the microstructure of the specimens and showed that the high strength could be attributed to strain hardening during cryorolling,with an additional contribution from grain refinement and the formation of dislocation walls.The high ductility could be attributed to annealing twins and micro-shear bands during stretching,which improved the strain hardening capacity.The results show that the synergistic effect of strength and ductility can be regulated through low-temperature short-time annealing with different cryorolling strains,which provides a new reference for the design of future thermo-mechanical processes.

Kalman Filter-Based CNN-BiLSTM-ATT Model for Traffic Flow Prediction

To accurately predict traffic flow on the highways,this paper proposes a Convolutional Neural Network-Bi-directional Long Short-Term Memory-Attention Mechanism(CNN-BiLSTM-Attention)traffic flow prediction model based on Kalman-filtered data processing.Firstly,the original fluctuating data is processed by Kalman filtering,which can reduce the instability of short-term traffic flow prediction due to unexpected accidents.Then the local spatial features of the traffic data during different periods are extracted,dimensionality is reduced through a one-dimensional CNN,and the BiLSTM network is used to analyze the time series information.Finally,the Attention Mechanism assigns feature weights and performs Soft-max regression.The experimental results show that the data processed by Kalman filter is more accurate in predicting the results on the CNN-BiLSTM-Attention model.Compared with the CNN-BiLSTM model,the Root Mean Square Error(RMSE)of the Kal-CNN-BiLSTM-Attention model is reduced by 17.58 and Mean Absolute Error(MAE)by 12.38,and the accuracy of the improved model is almost free from non-working days.To further verify the model’s applicability,the experiments were re-run using two other sets of fluctuating data,and the experimental results again demonstrated the stability of the model.Therefore,the Kal-CNN-BiLSTM-Attention traffic flow prediction model proposed in this paper is more applicable to a broader range of data and has higher accuracy.

Fabrication and Characterization of High-Bonding-Strength Al/Ti/Al-Laminated Composites via Cryorolling

Sandwich-like Al/Ti/Al-laminated composites have many advantages such as low density and high specific strength with value in mechanical manufacturing and aerospace engineering. Here, Al/Ti/Al-laminated composites were fabricated by hot roll bonding and subsequent processes: cryorolling(-190 ℃ and-100 ℃), cold rolling(25 ℃), and hot rolling(300 ℃). Their bonding strength and mechanical properties were then studied by an Autograph AGS-X universal electronic testing machine. The results show that cryorolling can improve the interface bonding strength and tensile strength of Al/Ti/Allaminated composites. For the Al/Ti/Al-laminated composites subjected to cryorolling at-100 ℃, they have the highest strength near 260 MPa—this is 48 MPa and 41 MPa higher than the laminated composites subjected to cold and hot rolling, respectively. These results also show the strongest peeling strength. Finally, the mechanisms of the enhancement of bonding strength and mechanical properties of Al/Ti/Al-laminated composites subjected to cryorolling were mainly discussed.

Supervised Analysis of Hepatitis C Virus RNA-Positive Case Reporting in County-Level Hospitals--China,2013−2018

What is already known on this topic?To understand the status of the diagnosis and reporting of hepatitis C and standardize the reporting of hepatitis C cases in county-level hospitals,we conducted the first supervised analysis of hepatitis C cases in county-level hospitals in China from 2013 to 2018,covering all provincial-level administrative divisions(PLADs)except Tibet.What is added by this report?Through 6 years of supervision,we have obtained key data such as the nucleic acid detection rate and positive rate of hepatitis C virus(HCV)antibody positive cases in our county-level hospitals,the report rate and accuracy of HCV RNA positive cases,and standardized and improved the hepatitis C case reporting in countylevel hospitals to improve data quality and provide data support for the judgment and estimation of hepatitis C in China.What are the implications for public health practice?By strengthening the management and supervision of hepatitis C case reporting,the reporting rate and accuracy of HCV RNA positive cases in county-level hospitals in China had been greatly improved.By combining the number of HCV antibody tests and the number of viral nucleic acid tests in medical institutions around the country,it was possible to effectively assess the current status of hepatitis C in China and to provide a scientific basis for the development of hepatitis C prevention and treatment measures.

Enhanced Mechanical Properties of AA5083 Matrix Composite via Introducing Al_(0.5)CoCrFeNi Particles and Cryorolling

High-entropy alloy particles(HEAPs)can markedly enhance the mechanical properties of metal matrix composites(MMCs).In this study,AA5083/Al_(0.5) CoCrFeNi HEAPs MMCs with diff erent HEAPs contents(0,1,and 3 wt%)were prepared via a stir-casting,and then these MMCs sheets were hot rolled(573 K)and cryorolled(77 K),respectively.The mechanical properties of the MMCs sheets were measured by tensile testing and microhardness test.Additionally,their microstructures were analyzed by scanning electron microscopy and transmission electron microscopy.Results revealed that the ultimate tensile strength(UTS)of the as-cast AA5083/Al_(0.5) CoC rF eN i HEAPs MMCs were improved from 203 to 257 MPa by adding 3 wt%HEAPs.And the mechanical properties of the MMCs sheets were improved after cryorolling.After cryorolling with 50%rolling reduction ratio,the MMCs with 1 wt%HEAPs had an UTS of 382 MPa,which was 1.9 times that of the MMCs before rolling.Finally,the strengthening mechanisms of HEAPs and cryorolling on the AA5083/HEAPs MMCs were discussed.

Large-scale synthesis of metal nanosheets as highly active catalysts: Combining accumulative roll-bonding and etching process

Metal nanosheets with ultrathin layer of metal atoms represent relatively high specific surface area and fast electronic transmission[1–2].Besides,metal nanosheets are considered to expose abundant active sites,thereby exhibiting significant advantages[3].As a result,metal nanosheets have attracted widespread attention in the field of catalysis[4–8],energy storage[9–10],environmental protection[11],and sensing[12]in recent years.For example,amorphous Ir nanosheets were found to be effectively applied to oxygen evolution reaction(OER)under acidic media with a high mass activity of 221.8 A·g^(–1)[4].