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111.
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。  相似文献   
112.
一种新的直扩超宽带系统快速同步方案   总被引:1,自引:0,他引:1  
王江  毕光国 《电路与系统学报》2005,10(3):120-123,139
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。  相似文献   
113.
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。  相似文献   
114.
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  相似文献   
115.
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.  相似文献   
116.
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.  相似文献   
117.
介绍新型节流装置——线性浮阀的结构、工作原理、特点及其在大型冷水机组中的应用以及实际使用中可能存在的问题,为在设计具有较高能效比的中大型冷水机组中,在节流机构选择应用上提供更大的选择空间。  相似文献   
118.
Tb3+,Mn2+作为激活剂的PDP绿色荧光粉的研究   总被引:1,自引:1,他引:0  
分别介绍了以Mn^2+和Tb^3+作为激活中心的PDP用硅酸盐体系、铝酸盐体系、硼酸盐体系和磷酸盐等体系绿色荧光粉的研究现状。在以Mn^2+作为发光中心的绿粉中,目前研究主要集中在通过调整Mn^2+的离子浓度、添加其他杂质,探索使用新的基质材料,或是使用不同的合成技术等方法来改进其余辉时间过长、易时效劣化以及形貌上的不足。在以Tb^3+作为激活中心的绿粉中,为了获取在真空紫外激发条件下高的发光效率,则主要围绕寻找在VUV区域内有强吸收的基质和能够有效进行能量传递的稀土敏化剂,以及利用量子剪裁效应来使得荧光粉发光量子效率大于1等方面进行。  相似文献   
119.
建立了人力资源管理的数理分析理论,研究了人力系统的平均经历、能量、系统的耦合与结构特征。  相似文献   
120.
Industrial pelletizing of sawdust was carried out as a designed experiment in the factors: sawdust moisture content, fractions of fresh pine, stored pine and spruce. The process parameters and response variables were energy consumption, pellet flow rate, pellet bulk density, durability and moisture content. The final data consisted of twelve industrial scale runs. Because of the many response variables, data evaluation was by principal component analysis of a 12 × 9 data matrix. The two principal component model showed a clustering of samples, with a good reproducibility of the center points. It also showed a positive correlation of energy consumption, bulk density and durability all negatively correlated to flow rate and moisture content. The stored pine was more related to high durability and bulk density. The role of the spruce fraction was unclear. The design matrix, augmented with the process parameters was a 12 × 6 matrix. Partial least squares regression showed excellent results for pellet moisture content and bulk density. The model for durability was promising. A 12 × 21 data matrix of fatty- and resin acid concentrations measured by GC–MS showed the differences between fresh and stored pine very clearly. The influence of the spruce fraction was less clear. However, the influence of the fatty- and resin acids on the pelletizing process could not be confirmed, indicating that other differences between fresh and stored pine sawdust have to be investigated. This work shows that it is possible to design the pelletizing process for moderate energy consumption and high pellet quality.  相似文献   
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