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]

Heavy Metal Occurrence, Pathways, and Associated Socio-ecological Risks in Riverine Water: Application of Geographic Information System, Multivariate Statistics, and Risk Assessment Models

The development of photocatalysts for selective esterification of aldehydes under visible light ‘’solar refinery’’ is greatly promising to solve the environmental and energy issues. Herein, key points were highlighted for the photo-assisted oxidation of benzaldehyde derivatives onto Sr-loaded TiO2 nanotubes facilitating the selectively aromatic aldehydes conversion to ester under visible light irradiation. Herein, strontium loading was investigated in a 0.2–1.0 wt%. Various spectroscopy techniques such as X-ray diffraction, N2 adsorption–desorption measurements, scanning electron microscopy coupled with energy-dispersive X-ray analysis, transmission electron microscopy, Raman, UV–vis diffuse reflectance, X-ray photoelectron and photoluminescence spectroscopies were used to fully characterize our samples. Our findings demonstrated that up to a Sr loading of 0.4 wt%, the addition of strontium induces an in-situ formation of high amount of oxygen vacancies Ov and Ti3+ entities on the surface of xSr-TiNT samples. However, the formation of segregated SrO species was observed when excess Sr loading was used. Photo-assisted oxidation of benzaldehyde derivatives occurs through competitive oxidation/reduction routes in the presence of photogenerated electron-hole pairs. Controlling the percentage of Ov provides a suitable tuning of the oxidation ability of photogenerated holes, avoiding over reduction to toluene and leading to a high selectivity into ester. Kinetically, oxygen vacancies induced by Sr acts as trap for photogenerated electrons. Moreover, the yield in ester increases following the Hammett constant, the highest yield being obtained for 2-hydroxybenzaldehyde (σ = -0.37). 

Visible-Light-Driven Selective Esterification of Benzaldehyde Derivatives using Strontium-Modified 1D Titanium Dioxide Nanotubes

In order to investigate the performance of priority  protocols in an eCommerce system, we simulate their behaviour when  composed with clients with differing behaviour. As suspected, we  find that the interaction between the clients and the server is an  important factor in the performance of the protocols.

Investigating Interactions between Clients and Server in the Performance Analysis of eCommerce Systems

Determination of Genetic Variation and Association Analysis of Yield Contributing Traits for Suitable Selection Criteria in Chickpea

/pdf/correction-to-mechanical-properties-and-weld-characteristics-2ng1ixmt.pdf

Muhammad Younas

Papers

Heavy Metal Occurrence, Pathways, and Associated Socio-ecological Risks in Riverine Water: Application of Geographic Information System, Multivariate Statistics, and Risk Assessment Models

Visible-Light-Driven Selective Esterification of Benzaldehyde Derivatives using Strontium-Modified 1D Titanium Dioxide Nanotubes

Investigating Interactions between Clients and Server in the Performance Analysis of eCommerce Systems

Determination of Genetic Variation and Association Analysis of Yield Contributing Traits for Suitable Selection Criteria in Chickpea

Correction to: Mechanical properties and weld characteristics of friction stir welding of thermoplastics using heat-assisted tool