Demixing in polystyrene/methylcyclohexane solutions

Cloudpoint data for polystyrene/methylcyclohexane solutions extending over moderate ranges of pressure and molecular weight are available in the literature. Those data are supplemented with new results from this laboratory to fill in gaps and extend the MW range (to 761 ≤ MW/amu ≤ 2 × 10⁷). The resulting data net is discussed and reasons to extend studies to higher pressure are presented. © 1996 John Wiley & Sons, Inc.     

A Closed‐Loop Control Strategy for Producing Nitrile Rubber of Uniform Chemical Composition in a Semibatch Reactor: A Simulation Study

To improve the quality of industrial nitrile rubbers, the copolymer chemical composition, p_A(t), should ideally be kept constant along the reaction. This work proposes a closed‐loop control strategy for the semibatch operation of the reactor with the aim of regulating p_A(t) within a reduced range of variability. The proposed strategy is evaluated by simulating a mathematical model of the process. To this effect, a simplified mathematical model of the reaction is first derived and then utilized to obtain a suboptimal control law and a soft‐sensor that estimates the polymerization rates. The suboptimal control law is compensated by adding a term proportional to errors in p_A(t). The simulated example considers the production of the low‐composition AJLT grade, with the copolymerization reaction represented by a detailed mathematical model adjusted to an industrial plant. Due to the high performance of the soft‐sensor, the simulation results suggest that the proposed closed‐loop strategy is efficient to adequately regulate p_A(t) in spite of structural and parametric uncertainties, while other quality variables remained practically unaffected.     

一种新型高效液相色谱二极管阵列检测器

研制了一种全封闭光学系统的高效液相色谱二极管阵列检测器。这种全封闭结构可以同时提高灵敏度、光谱分辨率和线性范围 ,对萘的最小检测量在2 30 nm下可达 1× 1 0 -10 g,且线性范围比为 5× 1 0 4。该检测器所采集的连续波长吸光度数据可以形成形象直观的三维谱图 ,以几种芳香类化合物为研究对象 ,验证了该系统的各项性能。     

Rearrangement of conditionally convergent series on a small set

We consider ideals I of subsets of the set of natural numbers such that for every conditionally convergent series _∑n∈ωan and every there is a permutation such that _∑n∈ωaπr(n)=r and

     

The α-limit sets of a unimodal map without homtervals

Let f:I→I be a unimodal map on I without homtervals. We characterize the α-limit set of each point in I by considering the consecutive renormalization process of f.     

Morse指标和闭测地线的稳定性

令ind(c)为n+1维Riemann流形M上闭测地线c的Morse指标.我们证明:对于闭测地线c,如果它是定向的且n+ind(c)是奇数,或它是非定向的且n+ind(c)为偶数,则c不稳定.Poincaré的一个著名定理说Riemann面上的极小闭测地线是不稳定的,我们的结果是该结论的一个推广.     

关于拓扑对策中的I~2(K)I(K)问题

证明了如果空间类κ为D-空间类或闭遗传不可约空间类,则I(κ)(∈)κ.这一结果对于κ为D空间类和闭遗传不可约空间类,肯定地回答了I(κ)是否包含I2(κ)问题.     

基于市场需求增加的双渠道闭环供应链定价机制研究

针对制造商开辟在线销售渠道现象的普及,考虑混合双渠道销售会增加产品的潜在需求,构建制造商与零售商分散、集中定价两种决策模型,利用博弈理论对模型进行求解分析,研究表明在双方分散、集中两种定价策略模型中,随着双渠道开通导致的市场需求率的增加,制造商的批发价、零售商的销售价格上调,零售商的回收价格下降,闭环供应链系统总利润则呈现先下降后上升的变化。最后,运用数值算例进一步验证和讨论双渠道销售导致的市场需求增加对闭环供应链系统定价策略、双方利润及系统渠道效率的影响。     

有限连续拓扑空间上的相交定理和广义变分不等式

根据已知的FC-空间上的KKM型定理得出若干个相交定理,作为它们的应用,利用转移开闭映射的特征讨论广义变分不等式解的存在问题.本文的结果改进和推广了文献中的相应结论.     

Gap formulas for closed linear relations

A classical formula for the gap between two densely defined closed operators in a Hilbert space is extended to the case of linear relations. Copyright © 2014 John Wiley & Sons, Ltd.