There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Praise for the Third Edition: "This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented."IIE Transactions on Operations EngineeringThoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than presenting a narrow focus on the subject, this update illustrates the wide-reaching, fundamental concepts in queueing theory and its applications to diverse areas such as computer science, engineering, business, and operations research.This update takes a numerical approach to understanding and making probable estimations relating to queues, with a comprehensive outline of simple and more advanced queueing models. Newly featured topics of the Fourth Edition include:Retrial queuesApproximations for queueing networksNumerical inversion of transformsDetermining the appropriate number of servers to balance quality and cost of serviceEach chapter provides a self-contained presentation of key concepts and formulae, allowing readers to work with each section independently, while a summary table at the end of the book outlines the types of queues that have been discussed and their results. In addition, two new appendices have been added, discussing transforms and generating functions as well as the fundamentals of differential and difference equations. New examples are now included along with problems that incorporate QtsPlus software, which is freely available via the book's related Web site.With its accessible style and wealth of real-world examples, Fundamentals of Queueing Theory, Fourth Edition is an ideal book for courses on queueing theory at the upper-undergraduate and graduate levels. It is also a valuable resource for researchers and practitioners who analyze congestion in the fields of telecommunications, transportation, aviation, and management science.

Fundamentals of Queueing Theory

/pdf/a-break-in-the-clouds-towards-a-cloud-definition-svovsw1r5a.pdf

A Break in the Clouds: Towards a Cloud Definition

CO2 conversion covers a wide range of possible application areas from fuels to bulk and commodity chemicals and even to specialty products with biological activity such as pharmaceuticals. In the present review, we discuss selected examples in these areas in a combined analysis of the state-of-the-art of synthetic methodologies and processes with their life cycle assessment. Thereby, we attempted to assess the potential to reduce the environmental footprint in these application fields relative to the current petrochemical value chain. This analysis and discussion differs significantly from a viewpoint on CO2 utilization as a measure for global CO2 mitigation. Whereas the latter focuses on reducing the end-of-pipe problem “CO2 emissions” from todays’ industries, the approach taken here tries to identify opportunities by exploiting a novel feedstock that avoids the utilization of fossil resource in transition toward more sustainable future production. Thus, the motivation to develop CO2-based chemistry does...

Sustainable Conversion of Carbon Dioxide: An Integrated Review of Catalysis and Life Cycle Assessment

Despite hospitality and tourism researchers’ recent attempts on examining different aspects of online word-of-mouth [WOM], its impact on hotel sales remains largely unknown in the existing literature. To fill this void, we conduct a study to empirically investigate the impact of online consumer-generated reviews on hotel room sales. Utilizing data collected from the largest travel website in China, we develop a fixed effect log-linear regression model to assess the influence of online reviews on the number of hotel room bookings. Our results indicate a significant relationship between online consumer reviews and business performance of hotels.

The impact of online user reviews on hotel room sales [Summary]

Software-as-a-Service (SaaS) is a model of cloudcomputing in which software functions are delivered to theusers as services. The past few years have witnessed itsglobal flourishing. In the foreseeable future, SaaSapplications will integrate with the Internet of Things,Mobile Computing, Big Data, Wireless Sensor Networks,and many other computing and communication technologiesto deliver customizable intelligent services to a vastpopulation.This will give rise to an era of what we call Big SaaSsystems of unprecedented complexity and scale. They willhave huge numbers of tenants/users interrelated in complexways. The code will be complex too and require Big Databut provide great value to the customer.With these benefits come great societal risks, however,and there are other drawbacks and challenges. Forexample, it is difficult to ensure the quality of data andmetadata obtained from crowdsourcing and to maintain theintegrity of conceptual model. Big SaaS applications willalso need to evolve continuously. This paper will discusshow to address these challenges at all stages of the softwarelifecycle.

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Big SaaS: The Next Step Beyond Big Data

Fault tolerance is an essential requirement for Web-databaseapplications, yet there has been little effort tospecify and verify techniques for crash recovery formally.This paper presents an extension to novel protocols(previously defined for Web-database transactionalapplications) so as to formally verify the correctness ofrecovery procedures in the presence of failures. Theprotocols presented manage complex transactionalapplications upon multiple and autonomouslyadministered Web-databases. Evaluation of theseprotocols shows that they enhance failure resilience,improve performance, and preserve the autonomy ofcomponent systems.

A formal verification strategy for crash recovery in web-database applications

Vehicular Ad-hoc Networks (VANETs) represent a rapidly emerging, particularly challenging class of Mobile Ad-hoc Networks (MANETs). VANETs are expected to be massively deployed in upcoming vehicles, because their use can improve the safety of driving and makes new forms of inter-vehicle communications possible as well. Because they are characterized of high mobility and dynamic topology change, congestion control should be performed in such networks. In this paper, we analyze the TCP traffic in a VANET. We investigate and compare the Good put of DYMO Protocol for TCP Vegas and TCP New Reno considering also the congestion window, slow-start threshold and sequence number versus time. The simulation results show that in this VANET scenario, TCP New Reno performs better than TCP Vegas.

Investigation of TCP Traffic in a Vehicular Ad-hoc Network Considering DYMO Routing Protocol

Ensuring accessibility of utility and social services is one of the public obligations of governments. Today, nations make use of the notion of e-government to expose such services to citizens. In line with this, many public organizations in Ethiopia are automating their workflows, and the Ministry of Communication and Information Technology (MCIT) is attempting to unify certain services as part of its e-government initiative. However, the architectural patterns in use generally lack the required flexibility, and scalability for future expansion needs and business models with respect to the option that latest technologies such as SOA can offer. Literature shows that the loosely-coupled nature of SOA addresses the above-mentioned limitations and many e-government initiatives are exploiting its potential. Thus, it is apparent that SOA can address the e-government needs in Ethiopia too. In this paper, we conducted an SOA e-readiness assessment against the available e-readiness frameworks and found out that the infrastructural, legal, government, customer, and human resource requirements are met. Thus, we recommend that SOA be applied to incrementally and loosely integrate the existing (and upcoming) systems and realize “ubiquitous” public service provision.

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Muhammad Younas

Papers

Big SaaS: The Next Step Beyond Big Data

A formal verification strategy for crash recovery in web-database applications

Investigation of TCP Traffic in a Vehicular Ad-hoc Network Considering DYMO Routing Protocol

Adopting SOA in Public Service Provision

Bipolar membrane electrodialysis for sustainable utilization of inorganic salts from the reverse osmosis concentration of real landfill leachate