Performance and Commercial Application of the Promoter LCC-A for Maximization of Propylene Yield

1 Introduction Propylene as an important feedstock for organic chemicals is mainly originated from steam cracking and catalytic cracking processes. During the FCC process the propylene content varies with the FCC catalyst and process technology adopted, resulting in significant difference in propylene concentration in the cracked product——LPG. The conventional FCC pro- cess generally gives a propylene yield of around 4%, while the FCC process with maximization of propylene yield can in…     

Trade-offs for conflicting social objectives in the extraction of finite energy resources

Three social objectives figure prominently in the extraction of finite energy resources, namely income maximization, environmental quality, and inter-generational concern. Owing to lack of complementarity, the pursuit of these objectives often results in conflicts. As a result, extraction strategies should be based on the determination of trade-offs between the objectives. The paper deals with the formulation and illustration of a systems model to determine these trade-offs. The recognition of such trade-offs results in a greater conservation of the finite energy resource, and hence could act as an incentive for the development of alternative energy sources.     

Linear variational principle for convex vector maximization

For infinitely dimensional convex vector maximization problems, it is proved that there exists, under certain conditions, an arbitrarily small additive perturbation of the performance criterion by a linear continuous operator such that the perturbed problem has efficient solutions. The study was sponsored by the Ukrainian State Fund for Basic Research __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 105–114, March–April 2007.     

基于级差最大化组合赋权法的地下水功能评价

针对地下水功能评价中单独采用主观赋权法或客观赋权法存在的问题,结合二者的优点,采用基于主观赋权的层次分析法与客观赋权的熵权法相结合的级差最大化组合赋权法评价地下水功能,并通过计算不同赋权方法权重结果与平均值的相对偏差来衡量级差最大化组合赋权法的准确性。将该方法应用于伊犁河谷西北部平原区浅层地下水功能评价,评价结果基本符合评价区实际情况,验证了该评价方法在地下水功能评价中的可行性。     

热含量不变量的SAR图像点特征变化检测

针对区域变化检测受分类器精度影响大、无法探测出内部细微变化这一问题,本文提出了基于热含量不变量的合成孔径雷达（Synthetic aperture radar,SAR）图像点特征变化检测.该方法利用热核特征,具有计算简便、矩阵扰动性小的特点,且有效地降低了噪声的干扰.由热核不变量的统计特性,采用期望极大化（Expectation maximization,EM）算法解决了SAR图像的自动变化检测.同时通过对权的讨论,给出了适用于SAR图像的权函数定义.对单波段单极化SAR与多极化SAR图像,本文算法相比于基于像素和似然比的方法,能够更快速更精确地检测到变化区域.     

无线传感网络中拥塞控制与路由的跨层设计:分布式牛顿法

无线传感网络应用广泛, 其性能与路由选择和拥塞控制密切相关. 致力于拥塞控制与多径路由的跨层优化, 以实现在链路容量受限和节点能量受限情况下的无线传感网络效用最大化. 针对对偶次梯度算法具有收敛速度慢与信息交互量大等缺陷, 设计了具有二阶收敛性能的分布式牛顿算法来实现网络效用最大化. 通过矩阵分裂技术, 实现了只需单跳信息交互的牛顿对偶方向的分布式求解方法. 仿真结果表明, 分布式牛顿算法的收敛性能显著优于对偶次梯度算法.     

Interactive fuzzy stochastic multi-level 0–1 programming using tabu search and probability maximization

In this paper, we consider interactive fuzzy programming for multi-level 0–1 programming problems involving random variable coefficients both in objective functions and constraints. Following the probability maximization model together with the concept of chance constraints, the formulated stochastic multi-level 0–1 programming problems are transformed into deterministic ones. Taking into account vagueness of judgments of the decision makers, we present interactive fuzzy programming. In the proposed interactive method, after determining the fuzzy goals of the decision makers at all levels, a satisfactory solution is derived efficiently by updating satisfactory levels of the decision makers with considerations of overall satisfactory balance among all levels. For solving the transformed deterministic problems efficiently, we also introduce novel tabu search for general 0–1 programming problems. A numerical example for a three-level 0–1 programming problem is provided to illustrate the proposed method.     

Price-based congestion control and local channel-link assignment for multi-radio wireless mesh networks

In multi-radio multi-channel wireless mesh networks, engineering the network capacity requires a complex cross-layer design. In this paper, in order to make the complex problem implementable in a distributed manner, we make a decoupling approach that breaks down the entire design space into routing and initial channel assignment, and distributed congestion control and local channel reassignment. We propose a unified priced-based framework for distributed congestion control and localized channel-link assignment algorithms. We demonstrate the convergence of the proposed algorithms with respect to different fairness objectives (i.e., proportional fairness and max–min fairness) via simulation on both grid and random topologies. The proposed algorithms achieve faster convergence with less overhead in the control and forwarding plane than previous multi-path based algorithms.     

多信道无线多跳网络的跨层优化

为提高多信道无线多跳网络的效用,提出了一种实际可行的跨层优化机制.  利用该机制,每个节点在传输层使用联合设计算法分布式地调整流速率,在链路层根据所提出的分布式调度算法进行速率分配;网关节点使用所提出的干扰代价最小的信道分配算法集中式地分配信道.  通过在层间和节点间传递信息来协调这些层的工作,比集中式算法降低了复杂度,减少了信令开销.  仿真结果表明,该机制具有快速收敛性,且能保证业务流间的公平性;随着可用射频和信道数目的增加,业务流的速率和网络效用增加.