Simulation of temperature field and metal flow during continuous semisolid extending extrusion process of 6201 alloy tube

A continuous semisolid extending extrusion （CSEP） method was proposed. Temperature field and metal flow during continuous semisolid extending extrusion process of 6201 alloy tube were studied. During the process, the temperature in the roll-shoe cavity decreases gradually, and the isothermal lines of the alloy deviate from the shoe side to the work roll side in the roll–shoe gap. Metal flow velocity decreases gradually from the surface of the work roll to the surface of the shoe. In the extrusion mould, alloy temperature decreases gradually from the entrance to the exit and from the center to the sidewall of the mould. The extending cavity is radially filled with the alloy. The flow lines in the tube corresponding to the centers of the splitflow orifices and the welding gaps are dense, and the corresponding harness values are high; there are 8 transitional bands between them. In order to prepare 6201 alloy tubes with good surface quality, the pouring temperature from 750 ℃ to 780 ℃ was suggested.

四方出击 八方来财──访贺君山夫妇

四方出击八方来财──访贺君山夫妇笔者趁下乡了解农民教育的机会，走访了湖南湘乡市泉塘镇双鲤村九组村民贺君山家．他家住在山坡旁一栋二层的小楼房。房屋背后，左侧栽了１００多株现已半成材的杉木，右边栽了几十株桔树，庭院布置得大方雅致。贺君山的妻子告诉我，她丈...

陕西植树史料(续六)

汉中府西乡县造林区域图说:西邑山多地少,并无旷土,平原概辟水田,荒山荒坡尽系杂树,间有隙地以及河岸、村边插柳、种桑。近亦渐兴林业,如东乡东沙坡一带,花栗树砍倒搭架能产木耳,私渡河松、杉等树能作木料,五里坝桐、漆等树能产桐、漆油。

才能在改革中闪光——记佳木斯市金属回收公司经理胡善彰

在改革的浪潮中,改革者不仅要有满腔热情,更需有战略的眼光、崭新的思路和科学的理性。市金属回收公司经理胡善彰就是这样的一个人。他用自己的实践和行动,使事业在改革中曝光。他不是医学家,却有高明的“医术”——改革管理体制,根治平均主义 1985年地市合并。

Microstructural and mechanical behavior of blended powder semisolid formed Al7075/B_4C composites under different experimental conditions

This work aimed to fabricate B4C reinforced aluminum matrix composites via blended powder semisolid forming that is an implementation of the benefits of semisolid forming to the powder metallurgy. Al7075 elements were incrementally added to ethanol solution under mechanical mixing. Al7075 constituents and B4C particles were blended in a high energy ball mill. Cold compacted Al7075/B4C blends were pressed at semisolid state. The effects of the size of the matrix（20, 45 and 63 μm）, reinforcing volume fraction（5%, 10% and 20%） and semisolid compaction pressure（50 and 100 MPa） on the morphology, microstructure, density, hardness, compression and bending strength were thoroughly analyzed. Experimental results revealed that the highest microstructural uniformity was achieved when large B4C particles（45 μm） were distributed within the small particles（20 μm） of the matrix phase. Composites with matrix particles larger than reinforcing phase indicated agglomerations in loadings more than 10%（volume fraction）. Agglomerated regions resisted against penetration of the liquid phase to the pores and lowered the density and strength of these composites. Composites with 20 μm Al7075 and 20%（volume fraction） 45 μm B4C powder pressed under 100 MPa exhibited the highest values of hardness（HV 190） and compressive strength（336 MPa）.

Review and Perspective of Architecture Development for Dynamic Random Access Memory

Discussed is a review and perspective of architecture, materials and process technology for dynamic random access memory(DRAM) applications. Key challenges of the transistor and capacitor scaling from DRAM will be reviewed. To continue scaling down, multi-gate devices with very thin silicon channels are most promising. Several architectures like Fin-field effect transistor(Fin-FET), Wafer bonded double gate and silicon on nothing(SON) gate-all-around have been demonstrated with good electrical characteristics. An overview of the evolution of capacitor technology is also presented from the early days of planar poly/insulator/silicon(PIS) capacitors to the metal/insulator/metal(MIM) capacitors used for today 50nm technology node and below. In comparing Ta2O5, HfO2 and Al2O3 as high-k dielectric for use in DRAM technology, Al2O3 is found to give a good compromise between capacitor performance and manufacturability used in MIM architecture.

为何判村委会来赔款

去年11月22日,山东省日照市小谷村乡法庭在处理小谷村乡山西头村村民王均庭诉村民王世堂损害赔偿案件时,结果山西头村委会赔偿了王均庭260.05元的经济损失。原来,1989年10月,村民王世堂建房,需占用王均庭院内的部分土地。在未领到小谷村乡政府批准建房的合法手续的情况下,村委会私下决定,让王世堂破土动工。为此,王世堂强行砍掉王均庭院内半成材树木34棵,并拆毁了院内一些设施。王均庭此后多次要求赔偿,

Design and fabrication of 1-D semiconductor nanomaterials for high-performance photovoltaics

To date, the cost-effective utilization of solar energy by photovoltaics for large-scale deployment remains challenging. Further cost minimization and efficiency maximization, through reduction of material consumption, simplification of device fabrication as well as optimization of device structure and geometry, are required. The usage of 1D nanomaterials is attractive due to the outstanding light coupling effect, the ease of fabrication, and integration with one-dimensional(1-D) semiconductor materials. The light absorption efficiency can be enhanced significantly, and the corresponding light-toelectricity conversion efficiency can be as high as their bulk counterparts. Also, the amount of active materials used can be reduced. This review summarizes the recent development of 1-D nanomaterials for photovoltaic applications, including the anti-reflection, the light absorption,the minority diffusion, and the semiconductor junction properties. With solid progress and prospect shown in the past 10 years, 1-D semiconductor nanomaterials are attractive and promising for the realization of high-efficiency and low-cost solar cells.

Green’s functions for infinite planes and half-planes consisting of quasicrystal bi-materials

This paper deals with the combination of point phonon and phason forces applied in the interior of infinite planes and half-planes of 1D quasicrystal bi-materials. Based on the general solution of quasicrystals, a series of displacement functions are adopted to obtain Green's functions for infinite planes and bi-material planes composed of two half-planes in the closed form, when the two half-planes are supposed to be ideally bonded or to be in smooth contact. Since the physical quantities can be readily calculated without the need of performing any transform operations, Green's functions are very convenient to be used in the study of point defects and inhomogeneities in the quasicrystal materials.

Ag4Hg（SeO3）2（SeO4）: a novel SHG material created in mixed valent selenium oxides by in situ synthesis

Explorations of new second harmonic generation materials in Ag^+-Hg^2+/Bi^3+-selenites systems afforded three new silver selenium oxides, namely, Ag4 Hg(SeO3)2(SeO4)(1), Ag2Bi2(SeO3)3(SeO4)(2) and Ag5 Bi(SeO3)4(3). They exhibit flexible crystal chemistry. Compounds 1 and 2 are mixed valence selenium oxides containing Se(IV) and Se(VI) cations simultaneously. Compounds 1 and 3 exhibit a 3 D open framework with 4-, 6-and 8-member polyhedral ring tunnels along a, b and c axes. Compound 1 crystallized in a polar space group and could display a subtle frequency doubling efficiency about 35% of the commercial KH2PO4(KDP). UV-vis-NIR spectra reveal that compounds 1–3 are wide-band semiconductors with the optical bandgaps of 3.11, 3.65, 3.58 e V respectively. Theoretical calculations disclose that compounds2 and 3 are indirect band gap structures and their bandgaps are determined by Ag, Bi, Se and O atoms together.