Structural evolution of matrix phase for liquid phase sintered 93W-4.9Ni-2.1Fe

The structure of the matrix of a two phase heavy alloy, 93W-4.9Ni-2.1Fe (wt%), was characterized. The matrix phase was not the expected face centred cubic Ni-Fe-W solid solution with a large grain size reported in the literature. Instead, an amorphous phase containing fine grained crystals as well as intermetallic compounds having different compositions were found. The partition of tungsten from the matrix toward the tungsten phase resulted in formation of different phases in the matrix. Under furnace cooling, the matrix phase was composed of an amorphous phase for the matrix phase remote from the tungsten grain-matrix interfaces, and a strained FeNi intermetallic phase near the interfaces. For specimens solution treated at temperatures between 1000–1400 °C followed by water quenching, an intermetallic phase rich in tungsten, (Ni, Fe) W, evolved and surrounded the tungsten grains in clusters. The relative abundance of this intermetallic phase was highest for a solution treatment temperature of 1400 °C, indicating that the formation of this phase was a result of supersaturation of tungsten in the matrix phase and retarded partition of tungsten from the matrix phase to tungsten grains under a rapid cooling condition.     

Efficient Skyline and Top-k Retrieval in Subspaces

Skyline and top-k queries are two popular operations for preference retrieval. In practice, applications that require these operations usually provide numerous candidate attributes, whereas, depending on their interests, users may issue queries regarding different subsets of the dimensions. The existing algorithms are inadequate for subspace skyline/top-k search because they have at least one of the following defects: 1) they require scanning the entire database at least once, 2) they are optimized for one subspace but incur significant overhead for other subspaces, or 3) they demand expensive maintenance cost or space consumption. In this paper, we propose a technique SUBSKY, which settles both types of queries by using purely relational technologies. The core of SUBSKY is a transformation that converts multidimensional data to one-dimensional (1D) values. These values are indexed by a simple B-tree, which allows us to answer subspace queries by accessing a fraction of the database. SUBSKY entails low maintenance overhead, which equals the cost of updating a traditional B-tree. Extensive experiments with real data confirm that our technique outperforms alternative solutions significantly in both efficiency and scalability.     

海洋丝状真菌转化石油烃的研究

研究从湄洲湾海域分离的4株丝状真菌MF1，MF2，MF3，MF4的生长特性及去除油污的过程，观察在温度26℃，初始油浓度在3g/l,培养12d的过程中培养液的变化，分析培养液的pH值及原油的去除率与时间的关系，结果表明，丝状真菌去除原油的[过程是生物吸附与生物降解相结合的生物转化过程，比较革兰氏阴性细菌与丝状真菌细胞壁组成，结构，得出海洋微生物的脱油作用与其细胞壁有直接的关系。     

一种基于EPID的安全OA系统

文章对OA系统中存在的安全问题进行了讨论,引人了一种新的基于远程匿名身份认证EPID模式,它能通过保存设备拥有者私密信息的硬件设施进行身份鉴定。一个嵌入EPID私密的硬件设备可以向远程机构证实它的有效性,而不必暴露自己的身份和其他私密信息。可以撤消一个签名的EPID私钥,即使不知道密钥的身份。同时,把EPID和其它的一些方法进行了对比。     

小型储气罐火灾工况数值模拟分析

以某输气管线气液联动执行机构中的储气罐为例,利用Ansys Fluent软件建立同比例三维模型,模拟火灾工况下,外部热量不断输入,罐内压力和罐体温度随时间的变化情况。利用Aspen Hysys软件模拟计算该小型储气罐在火灾工况下安全泄放所需的最小安全阀口径。结果表明,当钢制储气罐外部发生火灾时,罐体温度和罐内压力急剧升高,在很短的时间内就能达到储气罐坍塌温度和储气罐设计压力;达到钢制储气罐坍塌温度的时间滞后于达到储气罐设计压力的时间;从安全的角度,设置安全阀可安全有效泄放气体,即使储气罐发生坍塌,也有助于降低事故发生的危害程度;确定的安全阀最小口径为0.03 cm²,建议选型的安全阀口径不低于0.05 cm²。     

Photocatalytic syngas synthesis from CO2 and H2O using ultrafine CeO2-decorated layered double hydroxide nanosheets under visible-light up to 600 nm

The rational design of photocatalyst that can effectively reduce CO₂ under visible light(l>400 nm),and simultaneously precise control of the products syngas(CO/H2)ratio is highly desirable for the Fischer-Tropsch reaction.In this work,we synthesized a series of CeO₂-decorated layered double hydroxides(LDHs,Ce-x)samples for photocatalytic CO₂ reduction.It was found that the selectivity and productivity of CO and H₂ from photoreduction of CO₂ in conjunction with Ru-complex as photosensitizer performed an obvious“volcano-like”trend,with the highest point at Ce-0.15 and the CO/H₂ ratio can be widely tunable from 1/7.7 to 1/1.3.Furthermore,compared with LDH,Ce-0.15 also drove photocatalytic CO₂ to syngas under 600 nm irradiation.It implied that an optimum amount of CeO₂ modifying LDH promoted the photoreduction of CO₂ to syngas.This report gives the way to fully utilize the rare earth elements and provides a promising route to enhance the photo-response ability and charge injection efficiency of LDH-based photocatalysts in the synthesis of syngas with a tunable ratio under visible light irradiation.     

Synthesis and characterization of poly acrylic acid/graphite oxide nanocomposite

1　INTRODUCTIONOrganic intercalatedlayeredsolidshavebeenstudiedbyscientistsindifferentfieldsformanyyearsbecauseoftheirnew physicalandchemicalpropertiessuchaselectricalproperties[1] ,mechanicalproper ties ,thermalbehavior[2 ] ,surfaceandinterfacialproperties[3] .Graphiteoxide (GO)hasbeenstudiedformany years ,itsstructuralmodel[4 6 ] ,formationprocessandkinetics[7,8] havebeenstudiedindetail.IthasbeenreportedthatGOpossessesC OHande poxidefunctionalgroups[9] whichmakegraphiteox ideeasilyabs…     

炼厂硫腐蚀的典型案例分析及解决措施

通过硫在不同温度与环境下对金属材料腐蚀的典型案例分析，简述其腐蚀机理与解决,工对今后炼厂高硫油加工提出进一步建议。     

氟化铝生产废水处理工艺的研究

对氟化铝生产废水的处理方法进行了研究。结果表明，一级中和沉淀法和二级中和二级沉淀法均不宜用于氟化铝生产废水的结果，理想的处理方法是碱过量中和酸回调法，辅加氯化钙的石灰乳中和法也可考虑采用。     

碘仿电解合成的工艺研究

开发了一种以石墨为阳极、铅为阴极、采用旋转阳极和离子膜分隔电解槽的碘仿电解合成的先进工艺 ,经过 5因素 4水平的正交试验 ,发现影响电流效率的各工艺因素中 ,阳极电流密度的影响最大 ,其次分别为阳极液温度 ,阳极液 p H值 ,阳极液中碘化钾的浓度和阳极转速。优化得到碘仿电合成的最佳工艺条件为 :碘化钾浓度 2 0 0 g· L- 1 ,阳极电流密度 2 5 A· dm- 2 ,阳极液温度为 2 0℃ ,阳极液 p H值为 9.5,阳极转速为2 0 0 r· min- 1 ,在此最佳工艺条件下 ,电流效率可达 97.2 3%。