2,167 research outputs found
A model of power-biased technological change
New technologies have allowed firms to monitor low-skill workers more closely, thus reducing the power of these workers. We show that this ‘power-biased’ change may generate rising wage inequality and increases in the work intensity and unemployment of low-skill workers
Position-Based Multi-Agent Dynamics for Real-Time Crowd Simulation (MiG paper)
Exploiting the efficiency and stability of Position-Based Dynamics (PBD), we
introduce a novel crowd simulation method that runs at interactive rates for
hundreds of thousands of agents. Our method enables the detailed modeling of
per-agent behavior in a Lagrangian formulation. We model short-range and
long-range collision avoidance to simulate both sparse and dense crowds. On the
particles representing agents, we formulate a set of positional constraints
that can be readily integrated into a standard PBD solver. We augment the
tentative particle motions with planning velocities to determine the preferred
velocities of agents, and project the positions onto the constraint manifold to
eliminate colliding configurations. The local short-range interaction is
represented with collision and frictional contact between agents, as in the
discrete simulation of granular materials. We incorporate a cohesion model for
modeling collective behaviors and propose a new constraint for dealing with
potential future collisions. Our new method is suitable for use in interactive
games.Comment: 9 page
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Geological Science
Vertically emitting annular Bragg lasers using polymer epitaxial transfer
Fabrication of a planar semiconductor microcavity, composed of cylindrical Bragg reflectors surrounding a radial defect, is demonstrated. A versatile polymer bonding process is used to transfer active InGaAsP resonators to a low-index transfer substrate. Vertical emission of in-plane modes lasing at telecom wavelengths is observed under pulsed optical excitation with a submilliwatt threshold
Servitisation and value co-production in the UK music industry
Since the rise of music on the internet, record companies have reported falling sales of physical products. This has occurred at a time when technology has radically increased choice, availability and the opportunity for the consumer to purchase music. As the music industry has moved from a product to a service business model, has the loss of sales meant they have not taken their customers with them? This paper provides a description of different music consumers based upon quantitative analysis of consumer characteristics. The paper then undertakes an exploration of the relationship between the consumer groups and their purchasing preference in relation to intangible ‘service’ purchase such as downloaded music and the purchase of a tangible physical product such as CDs or vinyl. In addition, we analyse the relationship between consumer types and their propensity to actively engage with music
communities, such as through engagement with social media, and thus their willingness to coproduce greater value. Finally we explore the moderating effects of age and time devoted to listening to music on purchasing preferences and music discovery
Assessment of lithographic process variation effects in InGaAsP annular Bragg resonator lasers
Optical microresonators based on an annular geometry of radial Bragg reflectors have been designed and fabricated by electron-beam lithography, reactive ion etching, and an epitaxial transfer process. Unlike conventional ring resonators that are based on total internal reflection of light, the annular structure described here is designed to support optical modes with very small azimuthal propagation coefficient and correspondingly large free spectral range. The effect of lithographic process variation upon device performance is studied. Laser emission wavelength and threshold optical pump power are found to vary between similar devices given different electron doses during electron-beam lithography. As the resonance wavelength and quality factor of these resonators are very sensitive to environmental changes, these resonators make ideal active light sources that can be integrated into large arrays for gas and liquid sensing applications and are easily interrogated
Hybrid InGaAsP-InP Mach-Zehnder racetrack resonator for thermooptic switching and coupling control
An InGaAsP-InP optical switch geometry based on electrical control of waveguide-resonator coupling is demonstrated. Thermooptic tuning of a Mach-Zehnder interferometer integrated with a racetrack resonator is shown to result in switching with ON-OFF contrast up to 18.5 dB. The optical characteristics of this unique design enable a substantial reduction of the switching power, to a value of 26 mW in comparison with 40 mW for a conventional Mach-Zehnder interferometer switch. Modulation response measurements reveal a 3 dB bandwidth of 400 kHz and a rise time of 1.8 µs, comparing favorably with current state-of-the-art thermooptic switches
Low Threshold Two-Dimensional Annular Bragg Lasers
Lasing at telecommunication wavelengths from annular resonators employing
radial Bragg reflectors is demonstrated at room temperature under pulsed
optical pumping. Sub milliwatt pump threshold levels are observed for
resonators with 0.5-1.5 wavelengths wide defects of radii 7-8 mm. The quality
factors of the resonator modal fields are estimated to be on the order of a few
thousands. The electromagnetic field is shown to be guided by the defect. Good
agreement is found between the measured and calculated spectrum.Comment: 8 pages, 4 figure
Lasing from a circular Bragg nanocavity with an ultra-small modal volume
We demonstrate single-mode lasing at telecommunication wavelengths from a
circular nanocavity employing a radial Bragg reflector. Ultra-small modal
volume and Sub milliwatt pump threshold level are observed for lasers with
InGaAsP quantum well active membrane. The electromagnetic field is shown to be
tightly confined within the 300nm central pillar of the cavity. The quality
factors of the resonator modal fields are estimated to be on the order of a few
thousands.Comment: 3 pages, 4 figures Submitted to AP
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