6,276 research outputs found
Attack on the clones: managing player perceptions of visual variety and believability in video game crowds
Crowds of non-player characters are increasingly common in contemporary video games. It is often the case that individual models are re-used, lowering visual variety in the crowd and potentially affecting realism and believability. This paper explores a number of approaches to increase visual diversity in large game crowds, and discusses a procedural solution for generating diverse non-player character models. This is evaluated using mixed methods, including a “clone spotting” activity and measurement of impact on computational overheads, in order to present a multi-faceted and adjustable solution to increase believability and variety in video game crowds
Beyond Markov Chains, Towards Adaptive Memristor Network-based Music Generation
We undertook a study of the use of a memristor network for music generation,
making use of the memristor's memory to go beyond the Markov hypothesis. Seed
transition matrices are created and populated using memristor equations, and
which are shown to generate musical melodies and change in style over time as a
result of feedback into the transition matrix. The spiking properties of simple
memristor networks are demonstrated and discussed with reference to
applications of music making. The limitations of simulating composing memristor
networks in von Neumann hardware is discussed and a hardware solution based on
physical memristor properties is presented.Comment: 22 pages, 13 pages, conference pape
Polarisation oscillations in birefringent emitter-cavity systems
We present the effects of resonator birefringence on the cavity-enhanced
interfacing of quantum states of light and matter, including the first
observation of single photons with a time-dependent polarisation state that
evolves within their coherence time. A theoretical model is introduced and
experimentally verified by the modified polarisation of temporally-long single
photons emitted from a Rb atom coupled to a high-finesse optical cavity
by a vacuum-stimulated Raman adiabatic passage (V-STIRAP) process. Further
theoretical investigation shows how a change in cavity birefringence can both
impact the atom-cavity coupling and engender starkly different polarisation
behaviour in the emitted photons. With polarisation a key resource for encoding
quantum states of light and modern micron-scale cavities particularly prone to
birefringence, the consideration of these effects is vital to the faithful
realisation of efficient and coherent emitter-photon interfaces for distributed
quantum networking and communications.Comment: 9 pages, 5 figures including Supplemental Materia
Elementary methods for incidence problems in finite fields
We use elementary methods to prove an incidence theorem for points and
spheres in . As an application, we show that any point set of
with determines a positive proportion of
all circles. The latter result is an analogue of Beck's Theorem for circles
which is optimal up to multiplicative constants.Comment: 9 pages. In this new version, Theorem 3 has been significantly
improved, whilst the proof has been simplified. Also, Ben Lund has been added
as an autho
The trade and distribution of ceramics in the Western Indian Ocean 1250-1550AD An analysis of current available assemblages from Arabia, Iran and East Africa
This thesis is designed to make a generalized study of the ceramics present in the Western Indian Ocean during the period 1250AD- 1550AD, the period of expansion of the Hormuzi trading empire and its associated site of Julfar. The first part presents an analysis of the recently excavated assemblage from Julfar al-Nudud and then sets out to contextualize this within the wider Indian Ocean. Bringing in the available data from important trading sites in Arabia, southern Iran and East Africa, the work demonstrates a series of generalized assemblages based on period and geographical location, along with identifying a ‘ceramic trading’ assemblage for the study area. This puts forward that certain wares, generally Gulf and Chinese high- quality glazed wares are likely to be found on most sites involved in trade during this time, although not necessarily in great quantities. Other unglazed Iranian and Arabian storage wares, presumably traded for their contents rather than the vessel itself are found in greater quantities but individual wares vary between sites. The study finally identifies the areas where data is currently insufficient and suggests important future research questions for the study area
Bias in culture-independent assessments of microbial biodiversity in the global ocean
On the basis of 16S rRNA gene sequencing, the SAR11 clade of marine bacteria has almost universal distribution, being detected as abundant sequences in all marine provinces. Yet SAR11 sequences are rarely detected in fosmid libraries, suggesting that the widespread abundance may be an artefact of PCR cloning and that SAR 11 has a relatively low abundance. Here the relative abundance of SAR11 is explored in both a fosmid library and a metagenomic sequence data set from the same biological community taken from fjord surface water from Bergen, Norway. Pyrosequenced data and 16S clone data confirmed an 11-15% relative abundance of SAR11 within the community. In contrast not a single SAR11 fosmid was identified in a pooled shotgun sequenced data set of 100 fosmid clones. This under-representation was evidenced by comparative abundances of SAR11 sequences assessed by taxonomic annotation; functional metabolic profiling and fragment recruitment. Analysis revealed a similar under-representation of low-GC Flavobacteriaceae. We speculate that the fosmid bias may be due to DNA fragmentation during preparation due to the low GC content of SAR11 sequences and other underrepresented taxa. This study suggests that while fosmid libraries can be extremely useful, caution must be used when directly inferring community composition from metagenomic fosmid libraries
Multilevel convergence analysis of multigrid-reduction-in-time
This paper presents a multilevel convergence framework for
multigrid-reduction-in-time (MGRIT) as a generalization of previous two-grid
estimates. The framework provides a priori upper bounds on the convergence of
MGRIT V- and F-cycles, with different relaxation schemes, by deriving the
respective residual and error propagation operators. The residual and error
operators are functions of the time stepping operator, analyzed directly and
bounded in norm, both numerically and analytically. We present various upper
bounds of different computational cost and varying sharpness. These upper
bounds are complemented by proposing analytic formulae for the approximate
convergence factor of V-cycle algorithms that take the number of fine grid time
points, the temporal coarsening factors, and the eigenvalues of the time
stepping operator as parameters.
The paper concludes with supporting numerical investigations of parabolic
(anisotropic diffusion) and hyperbolic (wave equation) model problems. We
assess the sharpness of the bounds and the quality of the approximate
convergence factors. Observations from these numerical investigations
demonstrate the value of the proposed multilevel convergence framework for
estimating MGRIT convergence a priori and for the design of a convergent
algorithm. We further highlight that observations in the literature are
captured by the theory, including that two-level Parareal and multilevel MGRIT
with F-relaxation do not yield scalable algorithms and the benefit of a
stronger relaxation scheme. An important observation is that with increasing
numbers of levels MGRIT convergence deteriorates for the hyperbolic model
problem, while constant convergence factors can be achieved for the diffusion
equation. The theory also indicates that L-stable Runge-Kutta schemes are more
amendable to multilevel parallel-in-time integration with MGRIT than A-stable
Runge-Kutta schemes.Comment: 26 pages; 17 pages Supplementary Material
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