Measurement of Gibbs energies of formation of CoF2 and MnF2 using a new composite dispersed solid electrolyte

Gibbs energies of formation of CoF₂ and MnF₂ have been measured in the temperature range from 700 to 1100 K using Al₂O₃-dispersed CaF₂ solid electrolyte and Ni+NiF₂ as the reference electrode. The dispersed solid electrolyte has higher conductivity than pure CaF₂ thus permitting accurate measurements at lower temperatures. However, to prevent reaction between Al₂O₃ in the solid electrolyte and NiF₂ (or CoF₂) at the electrode, the dispersed solid electrolyte was coated with pure CaF₂, thus creating a composite structure. The free energies of formation of CoF₂ and MnF₂ are (± 1700) J mol⁻¹; {fx37-1} The third law analysis gives the enthalpy of formation of solid CoF₂ as ΔH° (298·15 K) = −672·69 (± 0·1) kJ mol⁻¹, which compares with a value of −671·5 (± 4) kJ mol⁻¹ given in Janaf tables. For solid MnF₂, ΔH°(298·15 K) = − 854·97 (± 0·13) kJ mol⁻¹, which is significantly different from a value of −803·3 kJ mol⁻¹ given in the compilation by Barinet al.     

无功补偿对远距离供电节能降耗的分析

本文从理论上分析了在不同功率因数下不同供电距离的能耗对比及近年来进行无功补偿的情况,从而说明了无功补偿对远距离供电节能降耗的重要意义。     

地下商场空调设计问题的探讨

本文分析了地下商场的特征 ,并相应提出了地下商场通风空调设计的有关数据、方法及注意事项     

Modeling of Energy Density Distribution in Rock Mass on the Basis of Seismotectonic and Geodetic Data

Using the focal mechanisms of earthquakes taken place from 1950 to 1996, the type and direction of principal strains were established, which made it possible to determine the volume stress-strain state of the south-east flank of the Baikal rift zone on the basis of the inverse problem solution. The variations in the stress-strain fields and spatial distribution of the stored potential energy density were found by the displacements of the daylight surface points in Tunkinsk geodetic proving ground in 1975 - 1986.     

武钢热轧厂层流冷却系统改造及节能效果

针对武钢热轧厂层流冷却系统能耗高，水压不稳，系统反应慢，供水泵工作效率低等缺陷，进行系统改造。提高了系统的控制精度和产品质量，节能降耗取得了明显的效果。     

一种新的直扩超宽带系统快速同步方案

本文提出了一种新的基于能量窗的直扩超宽带系统码片同步方法，通过设计具有重复特性的码来提高能量窗的信噪比，从向可以较为准确地获得码片同步，并将窗口中的信息作为接收端本地信号与接收信号进行匹配接收，这样可以存未知接收信号相位的情况下有效地接收多径能量，提高接收信噪比。在完成码片同步之后再进一步进行PN码的相位同步，这里以线性搜索为例分析得到超宽带信号总的平均同步时间，并与现有的超宽带同步方案进行了比较，新方案将信号捕获分成两部分完成，大大降低了超宽带信号捕获时间。     

合成氨扩能改造中锅炉存在的问题及采取的措施

针对天脊集团年产30万t合成氨扩能改造,给2台225t/h高压锅炉带来的除氧器热量过剩、锅炉给水温度升高、主蒸汽温度降低等一系列问题,分析了产生问题的原因,从节约能源、提高锅炉效率考虑,提出了相应的解决问题的办法:利用热量分流、改造省煤器管、增加二级过热器受热面积。经过3年多的生产实践证明,取得了良好的效果。     

Phase behavior of ternary blends containing dimethylpolycarbonate,tetramethylpolycarbonate and poly[styrene‐co‐(methyl methacrylate)] copolymers (or polystyrene)

The miscibility and phase behavior of ternary blends containing dimethylpolycarbonate (DMPC), tetramethylpolycarbonate (TMPC) and poly[styrene‐co‐(methyl methacrylate)] copolymer (SMMA) have been explored. Ternary blends containing polystyrene (PS) instead of SMMA were also examined. Blends of DMPC with SMMA copolymers (or PS) did not form miscible blends regardless of methyl methacrylate (MMA) content in copolymers. However, DMPC blends with SMMA (or PS) blends become miscible by adding TMPC. The miscible region of ternary blends is compared with the previously determined miscibility region of binary blends having the same chemical components and compositions. The region where the ternary blends are miscible is much narrower than that of binary blends. Based on lattice fluid theory, the observed phase behavior of ternary blends was analyzed. Even though the term representing the Gibbs free energy change of mixing for certain ternary blends had a negative value, blends were immiscible. It was revealed that a negative value of the Gibbs free energy change of mixing was not a sufficient condition for miscible ternary blends because of the asymmetry in the binary interactions involved in ternary blends. Copyright © 2004 Society of Chemical Industry     

Electrical conductivity of ferroelectric sodium vanadate,rubidium vanadate,cesium vanadate and their solid solutions

The d.c. electrical conductivity of sodium vanadate, rubidium vanadate, cesium vanadate and their solid solutions sodium-rubidium vanadate and sodium-cesium vanadate were studied by a two-probe method in the temperature range covering their transition points. The electrical conductivity shows sharp change at the phase transition temperature of these materials. In NaVO₃, RbVO₃ and CsVO₃, increase in d.c. conductivity is observed in the ferroelectric region while nonlinearities are observed above transition temperatures. In solid solutions, the activation energy in the paraelectric state is higher than that in the ferroelectric state and depends upon sodium concentration.     

A One-Dimensional Nonlocal Damage-Plasticity Model for Ductile Materials

This paper presents a new 1-D non-local damage-plasticity deformation model for ductile materials. It uses the thermodynamic framework described in Houlsby and Puzrin (2000) and holds, nevertheless, some similarities with Lemaitre’s (1971) approach. A 1D finite element (FE) model of a bar fixed at one end and loaded in tension at the other end is introduced. This simple model demonstrates how the approach can be implemented within the finite element framework, and that it is capable of capturing both the pre-peak hardening and post-peak softening (generally responsible for models instability) due to damage-induced stiffness and strength reduction characteristic of ductile materials. It is also shown that the approach has further advantages of achieving some degree of mesh independence, and of being able to capture deformation size effects. Finally, it is illustrated how the model permits the calculation of essential work of rupture (EWR), i.e. the specific energy per unit cross-sectional area that is needed to cause tensile failure of a specimen.