Media Ecologies

In this chapter, we frame the media ecologies that contextualize the youth practices we describe in later chapters. By drawing from case studies that are delimited by locality, institutions, networked sites, and interest groups (see appendices), we have been able to map the contours of the varied social, technical, and cultural contexts that structure youth media engagement. This chapter introduces three genres of participation with new media that have emerged as overarching descriptive frameworks for understanding how youth new media practices are defi ned in relation and in opposition to one another. The genres of participation—hanging out, messing around, and geeking out—refl ect and are intertwined with young people’s practices, learning, and identity formation within these varied and dynamic media ecologies

An Iowa Journal of Mathematics

The aim of this paper is to call the attention of Iowa scientists to the fact that in the development of mathematical periodicals Iowa has played a significant part. From January, 1874 to November, 1883 The Analyst, a Journal of Pure and Applied Mathematics was published in Des Moines by Joel E. Hendricks, a self-taught mathematician. This journal, started thirteen years after the last issue of the Mathematical Monthly of Boston (1859-1861), had the distinction of surviving longer than any previously published journal of its kind in the United States

An investigation of hydraulic-line resonance and its attenuation

An investigation of fluid resonance in high-pressure hydraulic lines has been made with two types of fluid dampers (or filters) installed in the line. One type involved the use of one or more closed-end tubes branching at right angles from a main line, and the other type was a fluid muffler installed in-line. These devices were evaluated in forced vibration tests with oscillatory disturbances over a 1000-Hz range applied to one end of the line and with oscillatory pressures measured at various stations along the main pipe. Limited applications of acoustic-wave theory to the branched systems are also included. Results show varying attenuations of pressure perturbations, depending on the number and location of branches and the type of muffler. Up to three branches were used in the branch-resonator study, and the largest frequency range with maximum attenuation was obtained for a three-branch configuration. The widest frequency ranges with significant attenuations were obtained with two types of fluid mufflers

Trailing Edge Noise Reduction by Passive and Active Flow Controls

This paper presents the results on the use of porous metal foams (passive control) and dielectric barrier surface plasma actuations (active control) for the reduction of vortex shedding tonal noises from the nonflat plate type trailing edge serration in a NACA0012 airfoil previously discussed in Chong et al. (AIAA J. Vol. 51, 2013, pp. 2665-2677). The use of porous metal foams to fill the interstices between adjacent members of the sawtooth can almost completely suppress the vortex shedding tonal noise, whilst the serration effect on the broadband noise reduction is retained. This concept will promote the nonflat plate type serrated trailing edge to become a genuine alternative to the conventional flat plate type serrated trailing edge, which is known to have drawbacks in the structural stability, aerodynamic performances and implementation issues. For the plasma actuators, configuration which produces electric wind in a tangential direction is found to be not very effective in suppressing the vortices emanated from the serration blunt root. On the other hand, for the plasma configuration which produces electric wind in a vertical direction, good level of vortex shedding tonal noise reduction has been demonstrated. However, the self noise produced by the plasma actuators negates the noise benefits on the tonal noise reduction. This characteristic illustrates the need to further develop the plasma actuators in a two pronged approach. First is to increase the electric wind speed, thereby allowing the plasma actuators to be used in a higher free jet velocity which naturally produces a larger level of jet noise. Second, the self noise radiated by the plasma actuators should be reduced

The Louisville and Nashville Railroad, 1850-1963

When the Louisville and Nashville Railroad was founded in 1850, it was the first major railroad in the west, and the only one headquartered in Kentucky. In the twentieth century, the L&N grew into one of the nation’s major rail systems, reaching from the Great Lakes to the Ohio River Valley and down to Florida and the Gulf Coast. Kincaid Herr worked for the Louisville and Nashville for more than forty years, and this book originated as a series of articles that he wrote for L&N Magazine between 1939 and 1942. After various printings through the 1940s and ’50s, this fifth edition, completely revised and updated, was released in 1964. The 1950s saw the reluctant abandonment of the old steam engine (the L&N was a major coal-carrying railroad) in favor of the diesel. During the late 1950s and early 60s, the railroad experienced significant expansion in the South, where the economy was being fueled by new industry. Coal, automobiles, mail, and passengers all counted on the L&N to get them around the region. Herr traces the development and expansion of the L&N system over a century and profiles important company figures, such as longtime L&N president Milton Smith. Confederate raider John Hunt Morgan and railroad bandit Morris Slater also find their place in this entertaining history. Four appendices on topics ranging from the materials used to build trains to passenger equipment to motive power round out the complete, but accessible, account. Even after all these years, this volume remains the concise, illustrated history of “The Old Reliable” for its many fans around the world. A classic and thorough history of an American institution. -- Bookman News, Library Booknotes Interesting and well illustrated. It should be a welcome gift for anyone who likes to read about railroads or the history of those states connected by the L & N Railroad. -- Bowling Green Daily News This is the best history of the L&N. -- Bulletin of the Railroad Station Historical Society Provides a well-written and richly detailed narrative of the evolution of America’s railroads of the world they did so much to shape. -- Carlos Schwantes A ‘jewel’ in railroad history. -- McCormick (SC) Messenger Illustrated with a veritable treasure trove of photographs and drawings spanning the life of the company. -- R. Lyle Key Jr. An important work for Tennessee and railroad history. -- Tennessee Librarian Herr has the knack for telling some fascinating tales about the L&N and its service territory. -- Historian A lively and broad look at ‘The Old Reliable.’ -- Trains It is a welcome event that this book is once again available. -- Anniston (AL) Starhttps://uknowledge.uky.edu/upk_united_states_history/1000/thumbnail.jp

Novel applications of the NASA/GSFC Viterbi decoder hardware simulator

The NASA/GSFC developed an all digital, real time, programmable Viterbi decoder simulator operating at rates up to 6 Msps. With this simulator, the bit error rate (BER) performance of convolutionally encoded/Viterbi decoded Shuttle-TDRSS return link channels under pulsed radio frequency interference (RFI) conditions has been predicted. The principles of the simulator are described with special emphasis on the channel simulator and the essential interaction between CLASS software and the simulator. The sensitivity of coded BER as function of several illustrative RFI parameters is discussed for two typical Shuttle-TDRSS return link configurations