Examination of dynamic recrystallization during compression of AZ31 magnesium

This study aimed to investigate dynamic recrystallization(DRX)behavior during compression of magnesium alloy AZ31. Cylinder samples were cut from the extruded rod and hot rolled sheet AZ31 for compression test.The samples were compressed using a Gleeble 1500D at a temperature of 300℃and a strain rate of 0.01 s-1.Grain orientations and misorientation angles across grain boundaries for the tested samples were obtained by using electron backscatter diffraction(EBSD)technique.The results showed that strong basal texture was observed after 50%compression(ε=0.69)on both the extruded and hot rolled samples,which have different initial textures.It was observed that with increased strain,DRX grains gradually rotated to basal orientation,and grain boundaries with misorientation angle of near 30°was formed in the samples.At the strain of 0.69,a high fraction of high-angle(60°)boundaries was present in the extruded sample,whereas almost no high angle boundaries were observed in the hot rolled sheet sample.     

Effects of Si and Ce on the microstructure and hydrogen storage property of Ti_(26.5)Cr_(20)V_(45)Fe_(8.5)Ce_(0.5) alloy

In this paper,the effects of Si and Ce on the microstructure and hydrogen storage property of Ti26.5 Cr20V45Fe8.5Ce0.5 alloy were studied,respectively.First of all,effects of Si on the microstructure and hydrogen storage properties of Ti26.5Cr20(V45Fe8.5)1-xSixCe0.5(x=0,0.5,1.0,1.5 and 2.0 at%)alloys were studied by X-ray diffraction,scanning electron microscopy and P-C isotherm measurements.As the Si addition increases,the hydrogen absorption capacities of alloys decrease but the equilibrium pressure incre...     

Magnetocaloric effect in Er-Al-Co bulk metallic glasses

A series of Er-Al-Co bulk metallic glasses (BMGs) have been prepared by the copper mold casting method. The glass forming ability and magnetocaloric effect (MCE) for these alloys have been investigated. The second-order magnetic transition from para-magnetic to ferromagnetic states takes place at about 9 K. These BMGs exhibit excellent MCE because of their large effective magneton number; Er56Al24Co20 BMG has a maximum entropy change and refrigeration capacity of 16.06 J kg-1 K-1 and 546 J kg-1,respectively...     

The determination of atmospheric phosphine in Ny-lesund

Phoshpine (PH3), a volatile and toxic gas, has been proved to commonly exist in the environment.The determination of gaseous phosphine and its emission fluxes in Ny-lesund is reported in this paper.Results showed that gaseous phosphine exist in Arctic atmosphere commonly and the concentration of phosphine ranged from 16.3-600.2 ng/m3, with the maximum concentration of phosphine in tundra areas and the minimum in surface air of ocean.The concentration of phosphine ranged from 65.79-1259 ng/m3 in colliery at...     

New Voronoi Diagram Algorithm of Multiply-Connected Planar Areas in the Selective Laser Melting

This paper studies the practical generation of Voronoi diagrams for multiply-connected planar areas bounded by line segments. The core of the algorithm was calculating Voronoi polygon of every Voronoi object in planar areas independently. The main approach had two steps. The first step was calculating all relevant bisectors of every Voronoi object. The second was combining obtained bisectors into completed Voronoi polygons individually. All code was implemented in Visual C++ platform. The resulting code was extensively tested in real-world data and its practical running time grew only linearly. Three statistical CPU-consumption charts had been drawn with the Voronoi diagrams computation data, and compared with other published codes for computing Voronoi diagrams. The algorithm was applied to compute offsetting of slice area consisting of large-scale line segments for the selective laser melting (SLM) trajectory scanning technology which is a kind of rapid prototyping (RP). The experimental results of offsetting for slice area based on Voronoi diagrams show that the approach is effective and simple for polygon offsetting problems. The method is helpful to those offsetting work and can provide more effective offsetting solution.     

Influence of Node Dynamics on Cluster Global Time Continuity

The cluster global time can change in wireless sensor networks due to leader re-elections and node disabilities between two successive synchronizations,which will affect temporal relationships.This paper analyzes cluster global time continuity,using global time change models for the node dynamics.The results prove that defining the global time using the cluster average time(AGT) is more stable than defining it using a single node’s local time(SGT).With normally distributed clock-parameter assumptions,the AGT change bounds are at most 70.7% of those for the SGT’s.The impacts of the initial phase and frequency skew distributions on the global time continuity are also investigated to show that the initial phase variations may strongly influence the continuity.Simulations show that the AGT is more stable with less disabled nodes or larger clusters.The appropriate cluster size is 20-40 when there are less than 15 disabled nodes.     

Universal Distributed Estimation Scheme for a Bandwidth Constrained Ad Hoc Sensor Network

This paper describes a distributed estimation scheme (DES) for a bandwidth constrained ad hoc sensor network.The DES is universal in the sense that operations on all sensors are identical and independent of noise distribution.The scheme requires each sensor to transmit just a 1-bit message per observation.Simulation results show that the scheme achieves much better mean-squares error (MSE) performance than the simplified isotropic universal DES and even outperforms the isotropic universal DES which requires more than twice the bandwidth of this scheme.     

Applying File Information to Block-Level Content Addressable Storage

Content addressable storage (CAS) is a promising technology for improving storage efficiency as well as access throughput.Currently,many CAS products are implemented on the block level,which results in loss of file information.Thus,some sophisticated optimizations cannot be achieved,such as accurate fileprefetching.This paper presents a file-aware block-level storage system combined with the CAS function.In contrast with some existing file-level CAS,this system is transparent to upper-level applications,including the operating system and the file system.These features are achieved by using smart-disk technologies to help the storage system to learn the file-system layout.A prototype was implemented on an open-source virtual machine (VM) with the guest operating system being Windows XP.Tests show that this combination significantly reduces the size of the VM image file and improves the storage performance by discarding unused blocks and using a simple file-level prefetching strategy.     

Fine-mapping of SRT7 for short roots and identification of its candidate in rice

Three allelic short root mutants were identified by screening mutants with defective root elongation of the rice japonica cultivar Nipponbare mutant library generated via 60 Co γ-ray irradiation mutagenesis. These mutants, designated srt7-1 (short root 7-1), srt7-2 and srt7-3, respectively, had an extremely short seminal root, adventitious roots and lateral roots. Histological observation revealed the cell length of srt7 mutant roots was significantly shorter than that of wild-type roots. Genetic analysis i...     

反相高效液相色谱法测定化妆品中的酮麝香

 酮麝香是化妆品中的限用物质,对人体有致癌作用,因此,有必要对其含量进行分析。采用超声辅助提取法对不同基质类型的化妆品样品进行预处理。利用反相高效液相色谱法测定化妆品中的酮麝香。色谱条件为Kromasil C₁₈(250mm×4.6mm i.d.,5μm)色谱柱,流动相V(乙腈):V(水)= 80:20,流速1.0mL/min,检测波长235nm。结果表明,在此条件下,酮麝香在0.5-150 μg/mL范围内与相应的峰面积具有良好的线性关系(相关系数r为0.9998),线性回归方程为A=13500ρ-4829,回收率为90.5%-102.5%,RSD为0.45%-0.98%。因此,研究建立的利用反相高效液相色谱法测定化妆品中的酮麝香的方法准确、可靠、适用性广,可为酮麝香的分析及国家相关法规的制定提供一定的参考。