Capacity Planning and Allocation for Web‐Based Applications

Motivated by the technology division of a financial services firm, we study the problem of capacity planning and allocation for Web‐based applications. The steady growth in Web traffic has affected the quality of service (QoS) as measured by response time (RT), for numerous e‐businesses. In addition, the lack of understanding of system interactions and availability of proper planning tools has impeded effective capacity management. Managers typically make decisions to add server capacity on an ad hoc basis when systems reach critical response levels. Very often this turns out to be too late and results in extremely long response times and the system crashes. We present an analytical model to understand system interactions with the goal of making better server capacity decisions based on the results. The model studies the relationships and important interactions between the various components of a Web‐based application using a continuous time Markov chain embedded in a queuing network as the basic framework. We use several structured aggregation schemes to appropriately represent a complex system, and demonstrate how the model can be used to quickly predict system performance, which facilitates effective capacity allocation decision making. Using simulation as a benchmark, we show that our model produces results within 5% accuracy at a fraction of the time of simulation, even at high traffic intensities. This knowledge helps managers quickly analyze the performance of the system and better plan server capacity to maintain desirable levels of QoS. We also demonstrate how to utilize a combination of dedicated and shared resources to achieve QoS using fewer servers.     

论闲暇教育对成人教育的意义

我国成人教育应该重视闲暇教育在提高成人素质和人的全面发展中的重要作用,积极开发闲暇教育的课程内容。这样既能满足人的精神需求,同时又潜在的提高了人的素质。     

Three methods of constructing pbib designs

Three construction methods of two- or three-associate partially balanced incomplete block (PBIB) designs are presented.     

INTRODUCING OR/MS INTO ORGANIZATIONS: NORMATIVE IMPLICATIONS OF SELECTED INDIAN EXPERIENCE*

There is considerable evidence that firms and institutions that have adopted and utilized operations research and related management sciences (OR/MS) experience severe internal disruptions and changes as the new technology is introduced. In some cases the reactions have been adverse enough to result in temporary rejection of the technology and a period of three to five years has been necessary for reintroduction of OR/MS. Such lags represent lost opportunities with attendant costs that firms and institutions can ill afford. There is obvious need to manage the introduction of OR/MS into organizations to minimize the inevitable resistances to change and to expedite institutional acceptance and practice. This paper presents a normative framework for this purpose based on four case studies of Indian implementation experience. The selected firms, which represent different sectors of industry, adopted different strategies for introduction and diffusion of OR/MS. The authors have noted several points of similarity between the Indian experience and the experience of U.S. organizations which indicate a fair measure of general validity for the proposed normative framework.