不同预时效挤压态Mg−Gd−Y−Zn−Zr合金的再结晶行为和强化机制

通过控制预时效时间制备3种不同状态的试样,研究不同预时效状态对挤压态Mg−9.5Gd−4Y−2.2Zn−0.5Zr(质量分数,%)合金的动态再结晶行为(DRX)和性能的影响。结果表明,欠时效挤压(UAE)样品的细晶体积分数为17.4%,而峰时效挤压(PAE)和过时效挤压(OAE)样品的细晶体积分数分别达到89.7%和50.4%。在晶粒内部和晶界处分布的致密、细小的β颗粒相通过粒子激发形核机制显著提高了形核位点和位错密度。然而,致密针状γ'相抑制位错滑移,延迟DRX形核。PEA和OAE样品中细小晶粒的差异归因于原始颗粒相的数量和尺寸的不同,而其拉伸性能的差异归因于不同的显微组织。由于晶界强化和析出强化机制的贡献更大,PAE样品具有更优异的拉伸性能。

Development of 3D printing entity slicing software

Based on STL(stereo lithography)format file and with Microsoft Visual C^(++)6.0 programming language,a 3D printing slicing software appropriate for the surface strengthening of the parts has been developed,which includes three functions:3D model import,model slicing and data export.Through the grouping of STL model triangle facets before slicing,the judgment times of the relationship between the triangle facets and the cutting planes are reduced,and the slicing efficiency is improved.Aiming at the fact that the surface should be strengthened when the part is formed by using of 3D printing process,the function of identifying and marking the surface of the geometric entity is accomplished in the slicing software,which can strengthen the surface of the part according to the user’s requirements.The developed slicing software can provide an entity slicing file for 3D printing equipment.The related functions can be adjusted and improved according to user’s needs,which makes the software convenient and flexible to use.

Establishing a Quality Control System of Hedyotis corymbosa

Objective Hedyotis corymbosa(Shui Xian Cao,水线草,HC)is the main antitumor medicine in China and other southeast Asian countries.A comprehensive quality control system of HC was established in this study,as the current system was ineffective.Methods Microscopy was used to observe the characteristics of the powder and cross-sectional tissue.Thin layer chromatography(TLC)was employed to separate HC from Hedyotis diffusa(Bai Hua She She Cao,白花蛇舌草,HD).Simultaneously,high-performance liquid chromatography(HPLC)was used to establish the characteristic spectrum of HC and determine the concentrations of hedyotiscone A.Regarding the issue of systematicness,concentrations of water,total ash,acid-insoluble ash,heavy metals(including lead,arsenic,mercury,cadmium and copper)and pesticide residue were measured by the methods described in the 2015 edition of Chinese Pharmacopoeia.Results Calcium oxalate needle crystal bundles and oil drops were observed in the cross-sectional tissue.Three characteristic blue fluorescent spots were observed in the HC samples by TLC.There were five distinct characteristic peaks in HC but not in HD,and hedyotiscone A was the sharpest characteristic peak.The generated linear equation of hedyotiscone A was Y=3.15×108X+312.04(r2=1.000)between 0.00005270 and 0.002108 mg/mL,and the average recovery was 100.42%.Precision[relative standard deviation(RSD)0.92%],repeatability(RSD 0.14%),and recovery(RSD 0.85%)met the requirements for quantitative analysis.Hedyotiscone A concentrations ranged from 0.00017%~0.00113%across different habitats.Concentrations of water,ash and acid-insoluble ash were 8.80%~11.2%,7.00%~15.3%and 0.440%~7.70%,respectively.Concentrations of Pb,As,Hg,Cd and Cu were 1.60~4.60,0.650~1.60,0.0300~0.100,0.240~0.690 and 10.1~16.6μg/g,respectively.Pesticide residues were less than 0.00100 ppm.Conclusion The quality control system can effectively distinguish HC from HD,so as to comprehensively control the quality of HC,to provide references for the clinical use of HC.

Correlation of serum NGAL and OPG contents with the change of carotid plaques in diabetic patients

Objective:To investigate the correlation of serum NGAL and OPG contents with the change of carotid plaques in diabetic patients.Methods: A total of 99 patients with type 2 diabetes mellitus combined with carotid plaque who were treated in our hospitals between February 2016 and March 2018 were selected as group A and 86 patients with carotid plaque alone were selected as group B. The serum contents of NGAL OPG, inflammatory markers and lipid metabolism indexes were compared between the two groups, and Pearson test was used to evaluate the inner link of serum NGAL and OPG contents with carotid plaque properties in diabetic patients with carotid plaques.Results: Serum NGAL content of group A was higher than that of group B whereas OPG content was lower than that of group B;serum inflammatory markers MMP-9, IL-1β, IL-17 and CRP contents were higher than those of group B;serum lipid metabolism indexes ApoB and Lp-PLA2 contents were higher than those of group B whereas ApoAⅠcontent was lower than that of group B. Correlation analysis showed that serum NGAL and OPG contents of patients with diabetes mellitus combined with carotid plaque were directly correlated with the content of inflammatory markers and lipid metabolism indexes.Conclusion: Serum NGAL content abnormally increases whereas OPG content abnormally decreases in patients with diabetes mellitus combined with carotid plaque, and they are directly correlated with the stability of carotid plaque.

Hot Compression Behavior of Mg-Gd-Y-Zn-Zr Alloy Containing LPSO with Different Morphologies

In this study,hot compression behavior of as-homogenized Mg-9Gd-4Y-2Zn-0.5Zr alloys containing long period ordered(LPSO)phases with different initial morphologies was investigated under a strain rate of 0.01 s−1 at 450°C.The microstructure,texture evolution and dynamic recrystallization(DRX)mechanism under different strains(0.1,0.3,0.5,0.7,and 1.4)were studied.Under compression conditions,the block-shape phase and deformedα-Mg matrix were regularly arranged vertically in the compression direction(CD).The particle phase(Mg5RE)and amount of kink bands were produced.The degree of kink increased initially and decreased significantly when the deformation strain reached 1.4.Three DRX mechanisms were produced during the compression process:(i)The block LPSO,Mg5RE and Zr-Zn phase activated DRX through the particle stimulated nucleation(PSN)mechanism.(ii)Several DRX activated on the serrated grain boundary between the two parent grains through discontinuous DRX(DDRX)mechanism.(iii)A large number of kink bands and larger spacing of lamellar LPSO increased the nucleation of DRX through continuous DRX(CDRX)mechanism.The combination of different recrystallization mechanisms has evident effects on grain refinement.DRX increased as compression proceeds,and the texture was gradually weakened.

An Efficient Network-on-Chip Router for Dataflow Architecture

Dataflow architecture has shown its advantages in many high-performance computing cases. In dataflow computing, a large amount of data are frequently transferred among processing elements through the network-on-chip （NoC）. Thus the router design has a significant impact on the performance of dataflow architecture. Common routers are designed for control-flow multi-core architecture and we find they are not suitable for dataflow architecture. In this work, we analyze and extract the features of data transfers in NoCs of dataflow architecture： multiple destinations, high injection rate, and performance sensitive to delay. Based on the three features, we propose a novel and efficient NoC router for dataflow architecture. The proposed router supports multi-destination; thus it can transfer data with multiple destinations in a single transfer. Moreover, the router adopts output buffer to maximize throughput and adopts non-flit packets to minimize transfer delay. Experimental results show that the proposed router can improve the performance of dataflow architecture by 3.6x over a state-of-the-art router.

Infl uence of Heat Treatment on Precipitation Behavior and Mechanical Properties of Extruded AZ80 Magnesium Alloy

By means of annular channel angular extrusion technology and solution treatment,the AZ80 supersaturated solid solu-tion was prepared.Theβ-Mg 17 Al 12 precipitate morphologies analysis along with its sizes and area fraction measurement was performed to investigate mechanical properties variation of alloy at various aging temperature.The results indicated that after solution treatment,the intergranular precipitate of as-extruded alloy was re-dissolved into the matrix,eff ectively decreasing the stress concentration,which was benefi cial to the enhancement of elongation.At aging temperatures of 300°C,Widmanstatten structure,lath-shaped precipitate,and intergranular precipitate were observed,while at 175–200°C,cellular structure and oval-shaped particle were also identifi ed.The morphology,area fraction,size of the precipitates,and PFZs(precipitate free zones)width worked together to aff ect the age-hardening behavior of the alloy.The strength and hardness of the peak-aged samples decreased with the increase in aging temperature,which is primarily attributed to the reduction in cellular structure area fraction and the corresponding increase in the interlamellar spacing,and the coarsening of the rhombus precipitate.

A Non-Stop Double Buffering Mechanism for Dataflow Architecture

Double buffering is an effective mechanism to hide the latency of data transfers between on-chip and off-chip memory. However, in dataflow architecture, the swapping of two buffers during the execution of many tiles decreases the performance because of repetitive filling and draining of the dataflow accelerator. In this work, we propose a non-stop double buffering mechanism for dataflow architecture. The proposed non-stop mechanism assigns tiles to the processing element array without stopping the execution of processing elements through optimizing control logic in dataflow architecture. Moreover, we propose a work-flow program to cooperate with the non-stop double buffering mechanism. After optimizations both on control logic and on work-flow program, the filling and draining of the array needs to be done only once across the execution of all tiles belonging to the same dataflow graph. Experimental results show that the proposed double buffering mechanism for dataftow architecture achieves a 16.2% average efficiency improvement over that without the optimization.

NATURAL SUPERCONVERGENT POINTS OF EQUILATERAL TRIANGULAR FINITE ELEMENTS - A NUMERICAL EXAMPLE

A numerical test case demonstrates that the Lobatto and the Gauss points are not natural superconvergent points of the cubic and the quartic finite elements under equilateral triangular mesh for the Poisson equation.

On a Nonparametric Estimator for the Finite Time Survival Probability with Zero Initial Surplus

In this paper, we consider the estimation of the finite time survival probability in the classical risk model when the initial surplus is zero. We construct a nonparametric estimator by Fourier inversion and kernel density estimation method. Under some mild assumptions imposed on the kernel, bandwidth and claim size density, we derive the order of the bias and variance, and show that the estimator has asymptotic normality property. Some simulation studies show that the estimator performs quite well in the finite sample setting.