Bi-Sr-Ca-Cu-O体系中可能存在一个新的高T_c超导相

最近,Pb能加强BiSrCaCuO超导体中高T_c相(即2223相,其c(?)37,T_c(?)110K)的出现和掺入sb形成BiPbSbSrCaCuO的T_c可以达到132 K已见报道,我们希望通过其它元素的掺杂取代也出现类似的结果。我们做了大量掺Sb、Ba、In的实验,通过改变

LaMSb_2O_7:R~(3+)(M=Li,Na,K;R=Eu,Dy,Bi)的合成、组成、结构及发光性能

研究了激活离子Eu~(3+),Dy~(3+)和Bi~(3+)在具有相同结构的LaMSb_2O_7(M=Li,Na,K)中的发光特性,得到了发白光的磷光体LaNaSb_2O_7:Dy~(3+)。讨论了化学键的共价程度对Eu~(3+)和Dy~(3+)超灵敏跃迁强度比的影响。发现当用281nm激发试样时,Bi~(3+)对Eu~(3+)具有敏化作用并解释了其原因。

Bi-Ce二元氧化物催化剂上丙烯氧化脱氢二聚的动力学与反应机理

丙烯在氧化物催化剂上氧化脱氢二聚反应的研究,文献上主要是在Bi-Sn系催化剂上进行的,不同研究者根据各自的结果,对这一步反应提出了两种不同的机理:一种认为是催化剂表面上吸附丙烯间的二聚(Langmuir-Hinshelwood型机)理;另一种认为是气相丙烯与吸附丙烯间的二聚(Eley-Rideal型机理).我们发现Bi-Ce二元氧化物显示出与Bi-

Sedimentary changes during the Holocene in the Bohai Sea and its paleoenvironmental implication

Samples of two cores, Cores M5-5 and M7-4 in the Bohai Sea were analyzed in isotopes, grain size, heavy minerals, chemical compositions, and 14 C dating to reconstruct the sedimentation during the Holocene. Abrupt change in carbon and oxygen stable isotopes was recognized at Core M5-5 at about 6400 a BP, which was likely due to the intrusion of the Yellow Sea Warm Current (YSWC) extension into the Bohai Sea. At Core M7-4, sediments between 5900 and 6600 a BP (150-260 cm depth) became coarse-grained, containing rich garnet, high manganese content, and nil autogenic pyrite, indicating a very dynamic sedimentary event during which the ambience was transformed from reductive to oxidative, and sedimentation boosted. Meanwhile, the YSWC had invaded into the Bohai Sea indicated by rich planktonic foraminifera in this event. (c) 2008 Elsevier Ltd. All rights reserved.

Mineral provinces and matter provenance of the surficial sediments in the western Philippine Sea: implication for modern sedimentation in West Pacific marginal basin

The characteristics and distribution patterns of detrital minerals (0.063 similar to 0.125 mm) in marine sediments provide a significant indicator for the identification of the origin of sediment. The detrital mineral composition of 219 surface sediment samples was analysed to identify the distribution of sediments within the western Philippine Sea. The area can be divided into three mineral provinces: ( 1) province east of the Philippine Trench, the detrital minerals in this province are mainly composed of calcareous or siliceous organisms, with the addition of volcanogenic minerals from an adjacent island arc; (II) middle mineral province, clastic minerals including feldspar, quartz and colorless volcanic glass, sourced from seamounts with intermediate-acid volcanic rock, or erupting intermediate-acid volcano; (III) province west of the Palau-Kyushii Ridge, the matter provenance within this province is complex; the small quantity of feldspar and quartz may be sourced from seamounts or erupting volcano with intermediate - acid composition, with a component of volcanic scoria sourced from a volcano erupting on the Palau-Kyushu Ridge. it is suggested that, ( I) Biogenic debris of the study area is closely related to water depth, with the amount of biogenic debris controlled by carbonate lysocline. (2) Volcaniclastic matter derived from the adjacent island are can be entrained by oceanic currents and transported towards the abyssal basin over a short distance. The weathering products of volcanic rocks of the submarine plateau ( e. g. I Benham Plateau) and adjacent ridges provide an important source of detrital sedimentation, and the influence scope of them is constrained by the intensity of submarine weathering. (3) Terrigenous sediments from the continent of Asia and the adjacent Philippine island arc have little influence on the sedimentation of this study area, and the felsic mineral component is probably sourced from volcanic seamounts of intermediate-acid composition.

Prediction of marine sediment corrosion by fuzzy clustering analysis

Along with the development of marine industries, especially marine petroleum exploitation, more and more pipelines are buried in the marine sediment. It is necessary and useful to know the corrosion environment and corrosiveness of marine sediment. In this paper, field corrosion environmental factors were investigated in Liaodong Bay marine sediment containing sulfate-reducing bacteria (SRB) and corrosion rate of steel in the partly sediment specimens were determined by the transplanting burying method. Based on the data, the fuzzy clustering analysis (FCA) was applied to evaluate and predict the corrosiveness of marine sediment. On that basis, the influence factors of corrosion damage were discussed.

An application of the analytic hierarchy process and fuzzy logic inference in a decision support system for forage selection

Forage selection plays a prominent role in the process of returning cultivated lands back into grasslands. The conventional method of selecting forage species can only provide attempts for problem-solving without considering the relationships among the decision factors globally. Therefore, this study is dedicated to developing a decision support system to help farmers correctly select suitable forage species for the target sites. After collecting data through a field study, we developed this decision support system. It consists of three steps: (1) the analytic hierarchy process (AHP), (2) weights determination, and (3) decision making. In the first step, six factors influencing forage growth were selected by reviewing the related references and by interviewing experts. Then a fuzzy matrix was devised to determine the weight of each factor in the second step. Finally, a gradual alternative decision support system was created to help farmers choose suitable forage species for their lands in the third step. The results showed that the AHP and fuzzy logic are useful for forage selection decision making, and the proposed system can provide accurate results in a certain area (Gansu Province) of China.

具有不完全微分的Fuzzy-GA PID控制器及其在智能仿生人工腿中的应用

以模糊推理和遗传算法为基础，提出了一种新的具有不完全微分的最优PID控制器的设计方法，该控制器由离线和在线两部分组成，在离线部分，以系统响应的超调量、上升时间以及调整时间为性能指标，利用遗传算法搜索出一组最优的PID参数Kp^*、Ti^*和Td^*，作为在线部分调整的初始值，在在线部分，一个专用的PID参数优化程序以离线部分获得Kp^*、Ti^*和Td^*为基础，根据系统当前的误差e和误差变化率e^.，通过一个模糊推理系统在线调整系统瞬态响应的PID参数，以确保系统的响应具有最优的动态和稳态性能．该控制器已被用来控制由作者设计的智能仿生人工腿中的执行电机．计算机仿真结果表明，该控制器具有良好的控制性能和鲁棒性能。

Optimal Fuzzy PID Controller with Incomplete Derivation and Its Simulation Research on Application of Intelligent Artificial Legs

提出了一种新的最优模糊PID控制器，它由两部分组成，即在线模糊推理机构和带有不完全微分的常规PID控制器，在模糊推理机构中，引入了三个可调节因子xp,xi和xd，其作用是进一步修改和优化模糊推理的结果，以使控制器对一个给定对象具有最优的控制效果，可调节因子的最优值采用ITAE准则及Nelder和Mead提出的柔性多面体最优搜索算法加以确定，这种PID控制器被用来控制由作者设计的智能人工腿中的一个直流电机，仿真结果表明该控制器的设计是非常有效的，它可被用于控制各种不同的对象和过程。

Fuzzy层次神经网络

本文提出和归纳了Ｆｕｚｚｙ前馈神经网络模型，并提出了Ｆｕｚｚｙ前馈神经网络的反向传播学习算法，模拟结果表明利用ＦｕｚｚｙＢＰ学习算法训练的Ｆｕｚｚｙ前馈神经网络具有较好的非逻辑归纳能力和Ｆｕｚｚｙ规则表达能力。

中国南方含硒建造中硒稳定同位素与化学形态的地质意义

氧化还原敏感元素硒的地球化学循环非常复杂, 它的循环主要受氧化还原势、酸碱度、温度、压力等条件的控制。长期以来，关于硒的主要研究集中在环境生物地球化学领域。对于硒的地质地球化学行为的研究，学者们认为硒不可能独立形成矿床,它主要以伴生元素的形式赋存于一些热液矿床（如，拉尔玛硒-金热液矿床等）。 二十世纪末, 我国学者开始关注硒的矿床地球化学行为, 发现了目前唯一的渔塘坝沉积型的独立硒矿床。另外，下寒武统底部黑色岩系（如，遵义牛蹄塘组）处于地球发展演化的关键时期且富集了众多的有用金属元素, 因此它引起了全世界广大地质学家的普遍关注和重视。这些黑色岩系的共同特点是含有大量的有机质和丰富的金属元素(PGE，Cu，Ni，Mo，Au，U，V，Mn，Fe，Co，Bi，Cr，Se等)。但遵义牛蹄塘组中Ni-Mo多金属层的成因一直争论不休。 本文以拉尔玛硒-金热液矿床、渔塘坝独立硒矿床、遵义黄家湾含Ni-Mo-Se多金属层剖面为研究对象，主要通过硒稳定同位素的测试和不同化学形态的分析结合其他的地球化学参数（如，C-S-Fe体系，氧化还原敏感元素），示踪富硒地层的沉积环境，研究不同地质体系中硒稳定同位素的组成，进而完善硒同位素的理论体系，探讨硒富集过程中的形态迁移途径，并为矿床的形成提供更完善的地球化学证据。通过一系列的研究工作，我们取得了以下几点认识： (1) 通过不同的消解方法准确测定了低硒,高硒样品的总硒含量,相对标准偏差小于10%，而且不同的消解方法测得同样的结果, 满足了地质样品中微量元素的测试要求。由于不同消解方式存在自身的优缺点,我们建议根据不同的样品类型,不同的研究目的选取合适的消解方法。 (2) 通过巯基棉吸附装置达到了纯化富集样品硒的目的, 硒的回收率一般大于90%, 满足同位素测试的需要。应用自制的氢化物发生器与Nu-MC-ICP-MS联用,实现了在线气体进样测试硒稳定同位素的目的。 采用标准样品匹配测试方法校正仪器测试过程中的质量分馏。 硒稳定同位素的测试精度为2δ=0.30‰, 标准NIST SRM 3149采用与样品同样的处理方法,没有发现前处理过程的同位素分馏。 (3) 传统地球化学参数对沉积环境的指示意义。通过氧化还原敏感微量元素及其与TOC的关系和C-S-Fe体系的分析，对渔塘坝独立硒矿床的多元素富集及沉积环境, 遵义黑色岩系沉积环境进行了详细的解释。TS-TFe的关系表明样品中有过量的硫存在，可能为有机硫或为其他亲硫元素提供有利的沉淀条件。C-S-Fe体系及微量元素指数V/(V + Ni) 说明渔塘坝矿区的硅质岩和页岩的沉积环境为缺氧到静海环境， Ni/Co、V/Cr几乎不能作为该区缺氧环境的指示参数, 后者可能由于Cr的外源输入（碎屑、热液等）所致。 C-S-Fe体系及微量元素指数V/(V + Ni)体系指示遵义黑色岩系的沉积环境为微含氧到缺氧的条件, 但对于Ni-Mo矿而言, V/(V + Ni)体系指示其为含氧条件沉积，这可能与Ni-Mo多金属层的成因有关。但铁的硫化度可以指示Ni-Mo多金属层极端的缺氧还原环境。 (4) 硒的形态对古氧化还原条件和矿物质来源的示踪意义。黑色岩系的硒形态分布不同于海洋沉积物，体现了成岩作用对硒形态分布的改变。黑色岩系中硒的主要形态为有机结合态和硫化物/硒化物结合态。硫化物/硒化物结合态比例与铁的硫化程度（DOS）之间明显的相关关系说明在海洋环境中硒主要通过氧化还原反应富集在富有机质的沉积物与沉积岩中。这种相关关系与岩石类型没有关系，这使得将硫化物、硒化物结合的Se（-II）比例作为一个氧化还原条件示踪剂更加可行。DOS与硫化物/硒化物结合态硒的关系，及Se（IV）与Se（-II）的关系均说明遵义牛蹄塘组的K-斑脱岩形成于碱性的氧化环境，Ni-Mo多金属层沉积于微酸性的极端还原环境，而渔塘坝矿床形成于微碱性的还原缺氧环境。生物的同化作用与异化作用之间本身存在互补关系，但这种互补关系却存在不同的转化趋势。不同的转化趋势可能主要受氧化还原反应和酸碱度的控制，其他的地质作用也可能起着重要作用（如，硅酸盐、Fe（II）的含量，硫化物、有机质含量，风化程度等）。同时我们发现相同的氧化还原条件下可能存在不同的富集途径。Ni-Mo多金属层中极少的有机结合态硒暗示海洋同生沉积主要被生物异化还原控制，而沉积物从海洋富集硒的途径主要为直接由Se（VI）和Se（IV）到Se（-II）的还原途径，从高价态到元素态的还原途径可能偶有发生但强度很小。 (5) 硒稳定同位素对矿床成因及物质来源的示踪意义。热液或表生环境中,硒的再次活化迁移对硒同位素的大范围分馏是很重要的。较少的硫化物结合态硒和较大范围的硒同位素组成说明渔塘坝矿床形成时经历了多次氧化还原过程。干酪根硒同位素组成与全岩相似, 而且样品富集轻同位素暗示该矿床硒来的富集主要通过海洋硒的生物吸收同化异化还原与多次无机氧化还原实现。对于拉尔玛金硒矿床而言，未蚀变岩体的硫化物结合态硒富集轻同位素，而后期低温流体的蚀变作用导致蚀变岩体中硫化物结合态硒富集重同位素。干酪根的硒同位素组成暗示热液输入的硒为该矿床硒的主要来源，硒从热液直接进入干酪根的机制是一致的。随着硫含量的增加岩石和矿体中的硒逐渐富集重同位素, 说明海水对矿床富集的贡献是很有限的。遵义黑色岩系中硒同位素组成与Se（-II）之间的关系, 单质硒的缺乏，硒的富集与同位素的关系说明，热液为主要的硒来源，而早寒武世海水中的硒主要通过Se（VI）和Se（IV）到Se（-II）的直接生物还原实现。三个区域的S/Se比值综合说明硫与硒的共同沉降过程中不存在硒的同位素分馏。不同化学形态的分布与不同形态中硒稳定同位素的结合可能会更好的解释硒的全球地球化学循环。 (6) 根据目前硒的同位素分馏体系及所测得的数据,我们初步建立了不同时代、不同成因黑色岩系中硒稳定同位素的分馏模式。