Robert J. Matthys
- Published in print:
- 2004
- Published Online:
- January 2010
- ISBN:
- 9780198529712
- eISBN:
- 9780191712791
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529712.001.0001
- Subject:
- Physics, History of Physics
The Shortt clock, made in the 1920s, is the most famous accurate clock pendulum ever known, having an accuracy of one second per year when kept at nearly constant temperature. Almost all of a ...
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The Shortt clock, made in the 1920s, is the most famous accurate clock pendulum ever known, having an accuracy of one second per year when kept at nearly constant temperature. Almost all of a pendulum clock's accuracy resides in its pendulum. If the pendulum is accurate, the clock will be accurate. This book describes many scientific aspects of pendulum design and operation in simple terms with experimental data, and little mathematics. It has been written, looking at all the different parts and aspects of the pendulum in great detail, chapter by chapter, reflecting the degree of attention necessary for making a pendulum run accurately. The topics covered include the dimensional stability of different pendulum materials, good and poor suspension spring designs, the design of mechanical joints and clamps, effect of quartz on accuracy, temperature compensation, air drag of different bob shapes and making a sinusoidal electromagnetic drive. One whole chapter is devoted to simple ways of improving the accuracy of ordinary low-cost pendulum clocks, which have a different construction compared to the more expensive designs of substantially well-made ones. This book will prove invaluable to anyone who wants to know how to make a more accurate pendulum or pendulum clock.Less
The Shortt clock, made in the 1920s, is the most famous accurate clock pendulum ever known, having an accuracy of one second per year when kept at nearly constant temperature. Almost all of a pendulum clock's accuracy resides in its pendulum. If the pendulum is accurate, the clock will be accurate. This book describes many scientific aspects of pendulum design and operation in simple terms with experimental data, and little mathematics. It has been written, looking at all the different parts and aspects of the pendulum in great detail, chapter by chapter, reflecting the degree of attention necessary for making a pendulum run accurately. The topics covered include the dimensional stability of different pendulum materials, good and poor suspension spring designs, the design of mechanical joints and clamps, effect of quartz on accuracy, temperature compensation, air drag of different bob shapes and making a sinusoidal electromagnetic drive. One whole chapter is devoted to simple ways of improving the accuracy of ordinary low-cost pendulum clocks, which have a different construction compared to the more expensive designs of substantially well-made ones. This book will prove invaluable to anyone who wants to know how to make a more accurate pendulum or pendulum clock.
Robert James Matthys
- Published in print:
- 2004
- Published Online:
- January 2010
- ISBN:
- 9780198529712
- eISBN:
- 9780191712791
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529712.003.0013
- Subject:
- Physics, History of Physics
The sphere and the vertically oriented cylinder are more repeatable and predictable bob shapes than the more efficient, lower-drag prolate spheroid and football shapes. As a bob shape, prolate ...
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The sphere and the vertically oriented cylinder are more repeatable and predictable bob shapes than the more efficient, lower-drag prolate spheroid and football shapes. As a bob shape, prolate spheroids have low air drag for their volume, and give a high Q pendulum. Only football-shaped bobs, that is, bobs with pointed ends (120 degrees included angles) in the direction of travel give a higher Q. A prolate spheroid shape can be obtained by rotating an ellipse 360 degrees around its long axis. The improved repeatability and predictability of spheres and vertically oriented cylinders can be attributed to their not having the rotational alignment uncertainty that is present in the prolate spheroid and football bob shapes.Less
The sphere and the vertically oriented cylinder are more repeatable and predictable bob shapes than the more efficient, lower-drag prolate spheroid and football shapes. As a bob shape, prolate spheroids have low air drag for their volume, and give a high Q pendulum. Only football-shaped bobs, that is, bobs with pointed ends (120 degrees included angles) in the direction of travel give a higher Q. A prolate spheroid shape can be obtained by rotating an ellipse 360 degrees around its long axis. The improved repeatability and predictability of spheres and vertically oriented cylinders can be attributed to their not having the rotational alignment uncertainty that is present in the prolate spheroid and football bob shapes.
Robert James Matthys
- Published in print:
- 2004
- Published Online:
- January 2010
- ISBN:
- 9780198529712
- eISBN:
- 9780191712791
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529712.003.0026
- Subject:
- Physics, History of Physics
A pendulum rod's air drag has a significant effect on the pendulum's Q. Many years ago, an experiment was carried out to determine the effect of bob shape on a pendulum's Q. The results showed that a ...
More
A pendulum rod's air drag has a significant effect on the pendulum's Q. Many years ago, an experiment was carried out to determine the effect of bob shape on a pendulum's Q. The results showed that a football-shaped bob, pointed horizontally in the direction of swing, had the highest Q (least air drag) of any bob shape tested. The highest Q shape had a 2:1 length-to-diameter ratio. Spherical bobs had a little lower Q and right circular cylinders, with their cylindrical axis parallel to the pendulum rod's axis, had even lower Q. This chapter describes an experiment to measure the effect of the pendulum rod on Q. The pertinent rod variable is the rod's diameter. The data show that the Q decreases as the rod's diameter increases, and that the pendulum's Q with a spherical bob is 6-20% better than with a cylindrical bob. Better Q means proportionately better timekeeping.Less
A pendulum rod's air drag has a significant effect on the pendulum's Q. Many years ago, an experiment was carried out to determine the effect of bob shape on a pendulum's Q. The results showed that a football-shaped bob, pointed horizontally in the direction of swing, had the highest Q (least air drag) of any bob shape tested. The highest Q shape had a 2:1 length-to-diameter ratio. Spherical bobs had a little lower Q and right circular cylinders, with their cylindrical axis parallel to the pendulum rod's axis, had even lower Q. This chapter describes an experiment to measure the effect of the pendulum rod on Q. The pertinent rod variable is the rod's diameter. The data show that the Q decreases as the rod's diameter increases, and that the pendulum's Q with a spherical bob is 6-20% better than with a cylindrical bob. Better Q means proportionately better timekeeping.
Robert James Matthys
- Published in print:
- 2004
- Published Online:
- January 2010
- ISBN:
- 9780198529712
- eISBN:
- 9780191712791
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529712.003.0028
- Subject:
- Physics, History of Physics
A previous experiment showed that the walls of a pendulum clock case can slow down the pendulum via air drag by about 1 second per day. The pendulum has a 2-second period. This chapter describes an ...
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A previous experiment showed that the walls of a pendulum clock case can slow down the pendulum via air drag by about 1 second per day. The pendulum has a 2-second period. This chapter describes an experiment designed to find out if the walls' drag on the pendulum could be reduced or made more constant by shaping the walls' inside surface for easier air flow. The concept basically involved rounding the square corners inside the clock case. The results show that a spherical bob had the smoothest airflow, while a large cylindrical bob disturbed the most air. There was very little, if any, air movement near the clock case walls. Any further attempt to affect the airflow should be aimed at the bob's surface-to-air interface, and not at the case walls.Less
A previous experiment showed that the walls of a pendulum clock case can slow down the pendulum via air drag by about 1 second per day. The pendulum has a 2-second period. This chapter describes an experiment designed to find out if the walls' drag on the pendulum could be reduced or made more constant by shaping the walls' inside surface for easier air flow. The concept basically involved rounding the square corners inside the clock case. The results show that a spherical bob had the smoothest airflow, while a large cylindrical bob disturbed the most air. There was very little, if any, air movement near the clock case walls. Any further attempt to affect the airflow should be aimed at the bob's surface-to-air interface, and not at the case walls.
Mark Wilson
- Published in print:
- 2006
- Published Online:
- January 2007
- ISBN:
- 9780199269259
- eISBN:
- 9780191710155
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199269259.003.0004
- Subject:
- Philosophy, Philosophy of Language
Because classical demands on conceptual understanding are quite strong and can prove potentially inhibiting within a scientific context, various philosopher/scientists in the late 19th century ...
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Because classical demands on conceptual understanding are quite strong and can prove potentially inhibiting within a scientific context, various philosopher/scientists in the late 19th century proposed that certain predicates could be provided with an alternative form of ‘meaning’ through distributed normativity, i.e., through implicit definition within a syntactic web of interconnection. Applied mathematics, however, warns that such globally unified webs often do not provide optimal descriptive platforms. On the basis of these considerations, it is argued that the ‘facades’ of Chapter 6 often represent better ‘linguistic engineering’ solutions to certain descriptive problems.Less
Because classical demands on conceptual understanding are quite strong and can prove potentially inhibiting within a scientific context, various philosopher/scientists in the late 19th century proposed that certain predicates could be provided with an alternative form of ‘meaning’ through distributed normativity, i.e., through implicit definition within a syntactic web of interconnection. Applied mathematics, however, warns that such globally unified webs often do not provide optimal descriptive platforms. On the basis of these considerations, it is argued that the ‘facades’ of Chapter 6 often represent better ‘linguistic engineering’ solutions to certain descriptive problems.
John J. Videler
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780199299928
- eISBN:
- 9780191714924
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199299928.003.0004
- Subject:
- Biology, Ornithology
Main forces on a flying bird are lift, weight, thrust, and drag. Quantitative visualization of the flow shows how these forces result from the interactions between bird and air. Conventional flow ...
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Main forces on a flying bird are lift, weight, thrust, and drag. Quantitative visualization of the flow shows how these forces result from the interactions between bird and air. Conventional flow around cambered arm wings with rounded leading edges and sharp trailing edges is attached and deflected downwards behind the wings. A starting vortex needs to be shed before the full lift force is produced. Hand wings with sharp leading edges are flat and often used in swept back position to induce leading edge vortices (LEVs) above the wing. LEVs produce lift and drag instantaneously. The aerodynamics of flapping flight is more complex than that of gliding flight because thrust needs to be generated as well as lift. Birds most probably use combined effects of attached and LEV flow to accelerate air downwards and backwards. Most tails operate as delta wings when spread. LEVs are probably the main aerodynamic mechanism.Less
Main forces on a flying bird are lift, weight, thrust, and drag. Quantitative visualization of the flow shows how these forces result from the interactions between bird and air. Conventional flow around cambered arm wings with rounded leading edges and sharp trailing edges is attached and deflected downwards behind the wings. A starting vortex needs to be shed before the full lift force is produced. Hand wings with sharp leading edges are flat and often used in swept back position to induce leading edge vortices (LEVs) above the wing. LEVs produce lift and drag instantaneously. The aerodynamics of flapping flight is more complex than that of gliding flight because thrust needs to be generated as well as lift. Birds most probably use combined effects of attached and LEV flow to accelerate air downwards and backwards. Most tails operate as delta wings when spread. LEVs are probably the main aerodynamic mechanism.
Fred Feldman
- Published in print:
- 2010
- Published Online:
- May 2010
- ISBN:
- 9780199571178
- eISBN:
- 9780191722547
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199571178.003.0003
- Subject:
- Philosophy, Moral Philosophy, Philosophy of Mind
In ‘Objective Happiness', Daniel Kahneman apparently means to offer an account of the nature of happiness. A person's objective happiness level at a moment (or “instant utility”) is defined as the ...
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In ‘Objective Happiness', Daniel Kahneman apparently means to offer an account of the nature of happiness. A person's objective happiness level at a moment (or “instant utility”) is defined as the extent to which he wants the experience he is having at that moment to continue. Objective happiness during an interval is the temporal integral of instant utilities for all the moments during the interval. Kahneman suggests that objective happiness is worth recording because it indicates happiness; and the welfare levels of citizens track their happiness so understood. However, arguments are presented that show it is doubtful that “objective happiness” is tightly related to anything we would ordinarily call happiness. It is also doubtful that it is related in any interesting way to welfare. A person can be very happy and doing well at a time even though she does not want her experience to continue.Less
In ‘Objective Happiness', Daniel Kahneman apparently means to offer an account of the nature of happiness. A person's objective happiness level at a moment (or “instant utility”) is defined as the extent to which he wants the experience he is having at that moment to continue. Objective happiness during an interval is the temporal integral of instant utilities for all the moments during the interval. Kahneman suggests that objective happiness is worth recording because it indicates happiness; and the welfare levels of citizens track their happiness so understood. However, arguments are presented that show it is doubtful that “objective happiness” is tightly related to anything we would ordinarily call happiness. It is also doubtful that it is related in any interesting way to welfare. A person can be very happy and doing well at a time even though she does not want her experience to continue.
Hiromitsu Ishi
- Published in print:
- 2001
- Published Online:
- November 2003
- ISBN:
- 9780199242566
- eISBN:
- 9780191596452
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/0199242569.003.0007
- Subject:
- Economics and Finance, South and East Asia
Discusses on the impact of income tax structure. It is widely acknowledged that the major goal of tax reductions was to adjust for the heavier tax burdens arising from inflation; at least it was true ...
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Discusses on the impact of income tax structure. It is widely acknowledged that the major goal of tax reductions was to adjust for the heavier tax burdens arising from inflation; at least it was true until the late 1980s. Thus it is necessary to clarify the mechanics of inflation adjustments via tax‐ cut policies.Less
Discusses on the impact of income tax structure. It is widely acknowledged that the major goal of tax reductions was to adjust for the heavier tax burdens arising from inflation; at least it was true until the late 1980s. Thus it is necessary to clarify the mechanics of inflation adjustments via tax‐ cut policies.
A.F. Borghesani
- Published in print:
- 2007
- Published Online:
- January 2008
- ISBN:
- 9780199213603
- eISBN:
- 9780191707421
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199213603.003.0008
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter describes the motion of charged quantized vortex rings in superfluid He II. The experimental results are presented and discussed. The striking behavior of the energy-velocity ...
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This chapter describes the motion of charged quantized vortex rings in superfluid He II. The experimental results are presented and discussed. The striking behavior of the energy-velocity relationship for charged vortex rings is presented in detail. The experimental results give a simple picture of an ion delocalized on the vortex ring circumference. Modern calculations of vortex dynamics have more or less confirmed this naive picture. The measurements of the mobility of the charged vortex rings have elucidated the role of the interaction of the ring with the elementary excitations of the superfluid, and have allowed the researchers to determine the structural characteristics of the rings.Less
This chapter describes the motion of charged quantized vortex rings in superfluid He II. The experimental results are presented and discussed. The striking behavior of the energy-velocity relationship for charged vortex rings is presented in detail. The experimental results give a simple picture of an ion delocalized on the vortex ring circumference. Modern calculations of vortex dynamics have more or less confirmed this naive picture. The measurements of the mobility of the charged vortex rings have elucidated the role of the interaction of the ring with the elementary excitations of the superfluid, and have allowed the researchers to determine the structural characteristics of the rings.
A. S. Argon
- Published in print:
- 2007
- Published Online:
- September 2007
- ISBN:
- 9780198516002
- eISBN:
- 9780191705717
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198516002.003.0004
- Subject:
- Physics, Crystallography: Physics
One of the most fundamental resistances to dislocation motion is that which the discrete lattice offers in a pure crystalline material in a temperature range where diffusion plays no role. This ...
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One of the most fundamental resistances to dislocation motion is that which the discrete lattice offers in a pure crystalline material in a temperature range where diffusion plays no role. This resistance will be considered from two mechanistically different points of view. First, the Peierls-Nabarro (PN) resistance is considered that results from the pulsing distortions of the dislocation core as it moves through the discrete lattice, affecting often the edge and screw dislocations differently and at very different levels in different crystal structures. Various models of this resistance affecting screw dislocations are examined in detail, leading to consideration of its temperature and strain rate dependence in many BCC metals, and to a lesser extent, in undoped diamond-cubic Si. Second, a form of ubiquitous resistance referred to as phonon drag, that arises from the interaction of moving dislocations with lattice thermal vibrations is presented. It is noted that the temperature dependence of phonon drag is radically different from that of the lattice resistance.Less
One of the most fundamental resistances to dislocation motion is that which the discrete lattice offers in a pure crystalline material in a temperature range where diffusion plays no role. This resistance will be considered from two mechanistically different points of view. First, the Peierls-Nabarro (PN) resistance is considered that results from the pulsing distortions of the dislocation core as it moves through the discrete lattice, affecting often the edge and screw dislocations differently and at very different levels in different crystal structures. Various models of this resistance affecting screw dislocations are examined in detail, leading to consideration of its temperature and strain rate dependence in many BCC metals, and to a lesser extent, in undoped diamond-cubic Si. Second, a form of ubiquitous resistance referred to as phonon drag, that arises from the interaction of moving dislocations with lattice thermal vibrations is presented. It is noted that the temperature dependence of phonon drag is radically different from that of the lattice resistance.
C. Winter Han
- Published in print:
- 2015
- Published Online:
- March 2016
- ISBN:
- 9781479831951
- eISBN:
- 9781479824700
- Item type:
- book
- Publisher:
- NYU Press
- DOI:
- 10.18574/nyu/9781479831951.001.0001
- Subject:
- Sociology, Gerontology and Ageing
In gay bars and nightclubs across America, and in gay-oriented magazines and media, the buff, macho, White gay man is exalted as the ideal. For gay Asian American men, often viewed by their peers as ...
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In gay bars and nightclubs across America, and in gay-oriented magazines and media, the buff, macho, White gay man is exalted as the ideal. For gay Asian American men, often viewed by their peers as submissive or too “pretty,” being sidelined in the gay community is only the latest in a long line of racially motivated offenses they face in the United States. Repeatedly marginalized by both the White-centric queer community that values a hyper-masculine sexuality and a homophobic Asian American community that often privileges masculine heterosexuality, gay Asian American men largely have been silenced and alienated in present-day culture and society. This book constructs a theory of queerness that is inclusive of the race and gender particularities of the gay Asian male experience in the United States. The book argues that gay Asian American men, used to gender privilege within their own communities, must grapple with the idea that, as Asians, they have historically been feminized as a result of Western domination and colonization, and as a result, they are minorities within the gay community, which is itself marginalized within the overall American society. It also shows that many Asian American gay men can turn their unusual position in the gay and Asian American communities into a positive identity. In their own conception of self, their Asian heritage and sexuality makes these men unique, special, and, in the case of Asian American drag queens, much more able to convey a convincing erotic femininity. Challenging stereotypes about beauty, nativity, the book makes a major intervention in the study of race and sexuality in America.Less
In gay bars and nightclubs across America, and in gay-oriented magazines and media, the buff, macho, White gay man is exalted as the ideal. For gay Asian American men, often viewed by their peers as submissive or too “pretty,” being sidelined in the gay community is only the latest in a long line of racially motivated offenses they face in the United States. Repeatedly marginalized by both the White-centric queer community that values a hyper-masculine sexuality and a homophobic Asian American community that often privileges masculine heterosexuality, gay Asian American men largely have been silenced and alienated in present-day culture and society. This book constructs a theory of queerness that is inclusive of the race and gender particularities of the gay Asian male experience in the United States. The book argues that gay Asian American men, used to gender privilege within their own communities, must grapple with the idea that, as Asians, they have historically been feminized as a result of Western domination and colonization, and as a result, they are minorities within the gay community, which is itself marginalized within the overall American society. It also shows that many Asian American gay men can turn their unusual position in the gay and Asian American communities into a positive identity. In their own conception of self, their Asian heritage and sexuality makes these men unique, special, and, in the case of Asian American drag queens, much more able to convey a convincing erotic femininity. Challenging stereotypes about beauty, nativity, the book makes a major intervention in the study of race and sexuality in America.
V. E. Fortov, I. T. Iakubov, and A. G. Khrapak
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780199299805
- eISBN:
- 9780191714948
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199299805.003.0011
- Subject:
- Physics, Nuclear and Plasma Physics
This chapter discusses the physics of complex (dusty) plasmas — low-temperature plasmas containing charged microparticles — and the major types of experimental dusty plasmas. Various elementary ...
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This chapter discusses the physics of complex (dusty) plasmas — low-temperature plasmas containing charged microparticles — and the major types of experimental dusty plasmas. Various elementary processes, including grain charging in different regimes, interaction between charged particles, and momentum exchange between different species are investigated. The major forces on microparticles and features of the particle dynamics in dusty plasmas are described. An overview of the wave properties in different phase states, as well as results on the phase transitions between different crystalline and liquid states are presented. Special attention is given to “crystallization” of dusty plasmas. Results of investigations of dusty plasmas under microgravity conditions are discussed in detail. Properties of plasmas with nonspherical particles are considered. Possible applications of dusty plasmas and new directions in experimental research are considered.Less
This chapter discusses the physics of complex (dusty) plasmas — low-temperature plasmas containing charged microparticles — and the major types of experimental dusty plasmas. Various elementary processes, including grain charging in different regimes, interaction between charged particles, and momentum exchange between different species are investigated. The major forces on microparticles and features of the particle dynamics in dusty plasmas are described. An overview of the wave properties in different phase states, as well as results on the phase transitions between different crystalline and liquid states are presented. Special attention is given to “crystallization” of dusty plasmas. Results of investigations of dusty plasmas under microgravity conditions are discussed in detail. Properties of plasmas with nonspherical particles are considered. Possible applications of dusty plasmas and new directions in experimental research are considered.
Dúnlaith Bird
- Published in print:
- 2012
- Published Online:
- September 2012
- ISBN:
- 9780199644162
- eISBN:
- 9780199949984
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199644162.003.0005
- Subject:
- Literature, European Literature
Cross-dressing in women’s travel writing of the nineteenth and twentieth centuries can be seen as a carnivalesque affair, featuring bearded ladies and flamboyant Queens. Using the performative gender ...
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Cross-dressing in women’s travel writing of the nineteenth and twentieth centuries can be seen as a carnivalesque affair, featuring bearded ladies and flamboyant Queens. Using the performative gender theories of Judith Butler and Marjorie Garber, this chapter questions the extent to which such theatrical cross-dressing allows European women travel writers to transgress social boundaries in their home and host countries. The first section of this chapter considers Jane Dieulafoy’s painstaking construction of textual legitimacy for her cross-dressing, which both invokes and abjures the legacy of bearded Queens by displacing it along Oriental cultural fault lines. It then examines the tensions that emerge in Isabella Bird’s travelogues as a result of the author’s determination to convincingly perform femininity in the Orient for her British audience. The final section explores Isabelle Eberhardt’s more radical constructions of linguistic and physical gender vagabondage in Algeria and Tunisia, and the restrictive social mechanisms they provoke.Less
Cross-dressing in women’s travel writing of the nineteenth and twentieth centuries can be seen as a carnivalesque affair, featuring bearded ladies and flamboyant Queens. Using the performative gender theories of Judith Butler and Marjorie Garber, this chapter questions the extent to which such theatrical cross-dressing allows European women travel writers to transgress social boundaries in their home and host countries. The first section of this chapter considers Jane Dieulafoy’s painstaking construction of textual legitimacy for her cross-dressing, which both invokes and abjures the legacy of bearded Queens by displacing it along Oriental cultural fault lines. It then examines the tensions that emerge in Isabella Bird’s travelogues as a result of the author’s determination to convincingly perform femininity in the Orient for her British audience. The final section explores Isabelle Eberhardt’s more radical constructions of linguistic and physical gender vagabondage in Algeria and Tunisia, and the restrictive social mechanisms they provoke.
J. M. Ziman
- Published in print:
- 2001
- Published Online:
- September 2007
- ISBN:
- 9780198507796
- eISBN:
- 9780191709937
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198507796.003.0010
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter considers the transport properties of charge carriers in semiconductors and near-insulators. That is, it discusses in detail the mobility and thermopower associated with a given density ...
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This chapter considers the transport properties of charge carriers in semiconductors and near-insulators. That is, it discusses in detail the mobility and thermopower associated with a given density of carriers introduced by some unspecified means into the conduction or valence band. Topics covered include spherical energy surfaces, scattering by impurities and imperfections, lattice scattering, scattering by optical modes, the many-valley model, Piezo resistance, and phonon drag.Less
This chapter considers the transport properties of charge carriers in semiconductors and near-insulators. That is, it discusses in detail the mobility and thermopower associated with a given density of carriers introduced by some unspecified means into the conduction or valence band. Topics covered include spherical energy surfaces, scattering by impurities and imperfections, lattice scattering, scattering by optical modes, the many-valley model, Piezo resistance, and phonon drag.
S. D. Ganichev and W. Prettl
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198528302
- eISBN:
- 9780191713637
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198528302.003.0004
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter is concerned with multiphoton transitions in the perturbative limit and beyond, resulting in fully developed nonlinearity where quantum interference effects control the absorption of ...
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This chapter is concerned with multiphoton transitions in the perturbative limit and beyond, resulting in fully developed nonlinearity where quantum interference effects control the absorption of photons. Of particular interest is the range beyond the perturbation limit which represents the transition from multiphoton absorption to tunneling. This transition is experimentally accessible only in the THz-range. The required intensities are very high but at THz frequencies still below the damage limit.Less
This chapter is concerned with multiphoton transitions in the perturbative limit and beyond, resulting in fully developed nonlinearity where quantum interference effects control the absorption of photons. Of particular interest is the range beyond the perturbation limit which represents the transition from multiphoton absorption to tunneling. This transition is experimentally accessible only in the THz-range. The required intensities are very high but at THz frequencies still below the damage limit.
S. D. Ganichev and W. Prettl
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198528302
- eISBN:
- 9780191713637
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198528302.003.0008
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter focuses on photoelectric phenomena. It describes a large number of mechanisms causing photocurrents like the photon drag effect, the linear and the circular photogalvanic effect, the ...
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This chapter focuses on photoelectric phenomena. It describes a large number of mechanisms causing photocurrents like the photon drag effect, the linear and the circular photogalvanic effect, the spin-galvanic effect, the magneto-gyrotropic effect, and other magnetic field-induced photocurrents, as well as terahertz radiation-induced monopolar spin orientation.Less
This chapter focuses on photoelectric phenomena. It describes a large number of mechanisms causing photocurrents like the photon drag effect, the linear and the circular photogalvanic effect, the spin-galvanic effect, the magneto-gyrotropic effect, and other magnetic field-induced photocurrents, as well as terahertz radiation-induced monopolar spin orientation.
J. M. Ziman
- Published in print:
- 2001
- Published Online:
- September 2007
- ISBN:
- 9780198507796
- eISBN:
- 9780191709937
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198507796.003.0009
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter discusses the electrical conductivity of metals. Topics covered include the transport properties of metals, residual resistance in alloys, the resistance-minimum phenomenon, residual ...
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This chapter discusses the electrical conductivity of metals. Topics covered include the transport properties of metals, residual resistance in alloys, the resistance-minimum phenomenon, residual resistance from crystal imperfections, the Bloch theory, lattice resistivity, electrical resistivity of transition metals, thermal conductivity, thermopower, phonon drag, and electron-electron scattering.Less
This chapter discusses the electrical conductivity of metals. Topics covered include the transport properties of metals, residual resistance in alloys, the resistance-minimum phenomenon, residual resistance from crystal imperfections, the Bloch theory, lattice resistivity, electrical resistivity of transition metals, thermal conductivity, thermopower, phonon drag, and electron-electron scattering.
Kiri Miller
- Published in print:
- 2012
- Published Online:
- May 2012
- ISBN:
- 9780199753451
- eISBN:
- 9780199932979
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199753451.003.0004
- Subject:
- Music, History, American, Ethnomusicology, World Music
This chapter addresses public gameplay performance contexts for Guitar Hero and Rock Band. What does it mean to be a live performer of a pre-recorded song? These games inspire physically virtuosic, ...
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This chapter addresses public gameplay performance contexts for Guitar Hero and Rock Band. What does it mean to be a live performer of a pre-recorded song? These games inspire physically virtuosic, visually engaging performances, staged in a variety of social contexts: players compete in game tournaments, post performances on YouTube, and form instant bands with friends at Rock Band bar nights. They also engage with the gender and sexuality norms of rock performance, sometimes turning their gameplay into over-the-top rock drag. As players and their audiences create these performances, they collaborate with game designers and recorded musicians in stitching recorded musical sound and performing bodies back together.Less
This chapter addresses public gameplay performance contexts for Guitar Hero and Rock Band. What does it mean to be a live performer of a pre-recorded song? These games inspire physically virtuosic, visually engaging performances, staged in a variety of social contexts: players compete in game tournaments, post performances on YouTube, and form instant bands with friends at Rock Band bar nights. They also engage with the gender and sexuality norms of rock performance, sometimes turning their gameplay into over-the-top rock drag. As players and their audiences create these performances, they collaborate with game designers and recorded musicians in stitching recorded musical sound and performing bodies back together.
Robert James Matthys
- Published in print:
- 2004
- Published Online:
- January 2010
- ISBN:
- 9780198529712
- eISBN:
- 9780191712791
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529712.003.0012
- Subject:
- Physics, History of Physics
Riefler's bob shape consists of two truncated cones, back-to-back. It is a shape with low air drag, and works well inside the clock case, where front-to-back space is frequently limited. A 1988 study ...
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Riefler's bob shape consists of two truncated cones, back-to-back. It is a shape with low air drag, and works well inside the clock case, where front-to-back space is frequently limited. A 1988 study on the air drag losses of various bob shapes found that the football and oblate spheroid shapes had even less drag than Riefler's two truncated cones. However, they require more front-to-back space, assuming equal volume, and are harder to make. Reducing a bob's air drag is worthwhile for two reasons. First, it reduces the weight needed to drive the escapement's gear train, which in turn reduces the wear on the gearing and the escapement's pallets. Second, the less you disturb a pendulum, the more accurate it becomes. For the lowest air drag, Riefler bobs should have an edge angle of 50-75 degrees and a diameter-to-thickness ratio of 2. Such bobs need 2% less drive force than a sphere of equal volume. This chapter also includes information on bob aerodynamics.Less
Riefler's bob shape consists of two truncated cones, back-to-back. It is a shape with low air drag, and works well inside the clock case, where front-to-back space is frequently limited. A 1988 study on the air drag losses of various bob shapes found that the football and oblate spheroid shapes had even less drag than Riefler's two truncated cones. However, they require more front-to-back space, assuming equal volume, and are harder to make. Reducing a bob's air drag is worthwhile for two reasons. First, it reduces the weight needed to drive the escapement's gear train, which in turn reduces the wear on the gearing and the escapement's pallets. Second, the less you disturb a pendulum, the more accurate it becomes. For the lowest air drag, Riefler bobs should have an edge angle of 50-75 degrees and a diameter-to-thickness ratio of 2. Such bobs need 2% less drive force than a sphere of equal volume. This chapter also includes information on bob aerodynamics.
Robert James Matthys
- Published in print:
- 2004
- Published Online:
- January 2010
- ISBN:
- 9780198529712
- eISBN:
- 9780191712791
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529712.003.0029
- Subject:
- Physics, History of Physics
Air drag is the biggest energy loss in a pendulum. The bob generates most of the air drag because of its large size and its location at the end of the pendulum rod. In this chapter, the movement of ...
More
Air drag is the biggest energy loss in a pendulum. The bob generates most of the air drag because of its large size and its location at the end of the pendulum rod. In this chapter, the movement of air around four different pendulum bobs is shown by white smoke in a series of pendulum photographs. The photos provide general information on airflow around the pendulum bob, but not much specific information that can be used to reduce the air drag and the pendulum's energy losses. Changing from a cylindrical to a spherical bob shape will reduce the energy losses and improve the pendulum's Q by 6-20%. But it takes about twice as much material (doubling the cost) and about four times as much effort to make a spherical bob as it does to make a cylindrical one. The best solution is to operate the clock in a vacuum chamber, although vacuum chambers have problems of their own.Less
Air drag is the biggest energy loss in a pendulum. The bob generates most of the air drag because of its large size and its location at the end of the pendulum rod. In this chapter, the movement of air around four different pendulum bobs is shown by white smoke in a series of pendulum photographs. The photos provide general information on airflow around the pendulum bob, but not much specific information that can be used to reduce the air drag and the pendulum's energy losses. Changing from a cylindrical to a spherical bob shape will reduce the energy losses and improve the pendulum's Q by 6-20%. But it takes about twice as much material (doubling the cost) and about four times as much effort to make a spherical bob as it does to make a cylindrical one. The best solution is to operate the clock in a vacuum chamber, although vacuum chambers have problems of their own.
