Mg_(0.15)Zn_(0.85)O:Tb合金薄膜的阴极射线发光性质研究

采用溶胶凝胶方法成功地制备了掺杂稀土铽离子的 Zn O和 Mg0 .1 5Zn0 .85薄膜。通过对 X射线衍射结果的分析表明 ,稀土离子替代了 Zn2 +的格位 ,进入了半导体基质的晶格中。从阴极射线发光结果可以发现 ,在Mg0 .1 5Zn0 .85O基质中 ,可以观察到来源于稀土铽离子各能级的发射 ,而 Zn O:Tb的薄膜只能观察到较强的铽离子 5D4 — 7F5能级的跃迁。这可能是由于 Mg0 .1 5Zn0 .85O基质的能隙 (3 .65 e V)比 Zn O更宽 (3 .3 e V) ,其对铽离子的能量传递更有效的缘故。     

武汉市长丰低闸施工期安全监测资料分析

对武汉市长江烂泥湖堤长丰低闸重建施工期间的安全监测资料进行了分析。重点分析了闸过水箱涵的结构缝开合、不均匀沉降等变形监测量变化特征及发展趋势 ,并由此对长丰低闸在施工期的安全状态进行了评判     

白钨矿浮选731捕收剂低温乳化试验研究

介绍了731捕收剂在低温条件下试验的情况。试验研究结果表明，采用A和B药剂以5：6的比例混合组成的复合乳化剂对731进行乳化，低温时乳化体系稳定性好，浮选过程中降低乳化731的用量，同时提高了选择性，降低了浮选成本，实现了低温环境下白钨矿正常浮选作业，达到选矿技术攻关指标。     

无线收、发信机的设计

主要讲述移动通信中收、发信机的工作原理、基本结构和组成.在给出收、发信机原理框图的同时,着重分析了锁相环路的设计.     

峡口水库沥青混凝土面板的施工与试验

以灌溉、防洪为主的峡口水库大坝，为沥青混凝土面板堆石坝，为研究低温抗裂性能，对沥青混凝土面板破损取样，进行了配比和多种力学性能试验，并与原面板设计指标进行了对比。由于面板经受住了－20℃以下的低温考验，其所用沥青指标、破损取样试验结果，特别是冻断低温指标，对确定水工沥青混凝土低温抗裂检验标准有重要参考价值。     

特大型桥梁工程地质勘察区域地壳稳定性研究

重大工程区域地壳稳定性研究，是工程前期工程地质勘察的重要内容之一，并越来越多地为工程建设所重视。大桥工程地质勘察以往对此涉及较少，也无明确的统一规定，以长江上所建特大桥为例，对此项工程作了些探索性的研究，重点研究的问题是：区域构造环境及构造变形，地壳结构和深部构造，新构造活动，断裂活动，地震活动等，为大桥建设宏观决策和抗震设计提供依据。     

A novel compact circuit for 4-PAM energy-efficient high speed interconnect data transmission and reception

Transmission of signals, whether on-chip or off-chip, places severe constraints on timing and extracts a large price in energy. New silicon device technologies, such as back-plane CMOS, provide a programmable and adaptable threshold voltage as an additional tool that can be used for low power design. We show that one particularly desirable use of this freedom is energy-efficient high-speed transmission across long interconnects using multi-valued encoding. Our multi-valued CMOS circuits take advantage of the threshold voltage control of the transistors, by using the signal-voltage-to-threshold-voltage span, in order to make area-efficient implementations of 4-PAM (pulse amplitude modulation) transceivers operating at high speed. In a comparison of a variety of published technologies, for signal transmission with interconnects of 10-15 mm length, we show up to 50% improvement in energy for on-chip signal transmission over binary encoding together with higher limits for operating speeds without a penalty in circuit noise margin.     

Rare earth oxides as carbon oxidation catalysts

The behavior of a number of rare earth oxides as catalysts for the oxidation of graphite in air has been investigated by the methods of thermal analysis. Of the oxides studied, only CeO₂ showed significant activity in accelerating the gasification of graphite by oxygen between 500 and 1000°C. Cerium salts, which decompose to a finely dispersed oxide phase at low temperatures, e.g. Ce (III) nitrate and ammonium Ce (IV) nitrate, were found to be very active catalysts. The catalytic effect may be due to a redox process involving the cyclic conversion of the oxide from the Ce (IV) to the Ce (III) oxidation state, or the oxide particles may provide sites for the dissociative chemisorption of oxygen.     

Interferometric monitoring of satellite longitudes

This paper proposes a technique for monitoring the longitudinal motion of geosynchronous satellites. A two‐antenna interferometer is used, with the baseline orientation adjusted to a particular horizontal azimuth. The interferometer then becomes insensitive to the north–south motion of the satellite, and this enables direct measurement of the satellite's longitudinal motion. Longitudes are monitored continuously, with no delay when orbital manoeuvres occur. The proposed technique is particularly useful when two or more satellites are operating in close proximity and their longitudes must be precisely monitored for safety control. Copyright © 2005 John Wiley & Sons, Ltd.     

Ring‐opening polymerization of D,L‐lactide by rare earth 2,6‐dimethylaryloxide

Ring‐opening polymerization of D,L ‐lactide (LA) has been successfully carried out by using rare earth 2,6‐dimethylaryloxide (Ln(ODMP)₃) as single component catalyst or initiator for the first time. The effects of different rare earth elements, solvents, monomers and catalyst concentration as well as polymerization temperature and time on the polymerization were investigated. The results show that La(ODMP)₃ exhibits higher activity to prepare poly(D,L ‐lactide) (PLA) with a viscosity molecular weight of 4.5 × 10⁴ g mol^?1 and the conversion of 97 % at 100 °C in 45 min. The catalytic activity of Ln(ODMP)₃ has following sequence: La > Nd > Sm > Gd > Er > Y. A kinetic study has indicated that the polymerization is first order with respect to both monomer and catalyst concentration. The apparent activation energy of the polymerization of LA with La(ODMP)₃ is 69.6 kJ mol^?1. The analyses of polymer ends indicate that the LA polymerization proceeds according to ‘coordination–insertion’ mechanism with selective cleavage of the acyl–oxygen bond of the monomer. Copyright © 2004 Society of Chemical Industry