1,670 research outputs found
Simulation Environment for Artificial Creatures
Our research is focused on the design and simulation of artificial creatures – animates. This topic has been addressed in our research group for the last decade. The designed animates have been greatly inspired by sciences such as ethology, biology and psychology. Several agent architectures have been proposed and tested in recent years. We started to face the problem of comparing various architectures in order to benchmark them. Intelligence is embodied in our agent, and it needs an environment to be placed into. We have solved both these problems by first proposing and then implementing a common simulation environment in which these agents can run and compete. The main contribution of this paper is to offer a description of this designed simulation environment. It has been named the World of Artificial Life (WAL).
Optimal, reliable estimation of quantum states
Accurately inferring the state of a quantum device from the results of
measurements is a crucial task in building quantum information processing
hardware. The predominant state estimation procedure, maximum likelihood
estimation (MLE), generally reports an estimate with zero eigenvalues. These
cannot be justified. Furthermore, the MLE estimate is incompatible with error
bars, so conclusions drawn from it are suspect. I propose an alternative
procedure, Bayesian mean estimation (BME). BME never yields zero eigenvalues,
its eigenvalues provide a bound on their own uncertainties, and it is the most
accurate procedure possible. I show how to implement BME numerically, and how
to obtain natural error bars that are compatible with the estimate. Finally, I
briefly discuss the differences between Bayesian and frequentist estimation
techniques.Comment: RevTeX; 14 pages, 2 embedded figures. Comments enthusiastically
welcomed
A Processor Extension for Cycle-Accurate Real-Time Software
Certain hard real-time tasks demand precise timing of events, but the usual software solution of periodic interrupts driving a scheduler only provides precision in the millisecond range. NOP-insertion can provide higher precision, but is tedious to do manually, requires predictable instruction timing, and works best with simple algorithms. To achieve high-precision timing in software, we propose instruction-level access to cycle-accurate timers. We add an instruction that waits for a timer to expire then reloads it synchronously. Among other things, this provides a way to exactly specify the period of a loop. To validate our approach, we implemented a simple RISC processor with our extension on an FPGA and programmed it to behave like a video controller and an asynchronous serial receiver. Both applications were much easier to write and debug than their hardware counterparts, which took roughly four times as many lines in VHDL. Simple processors with our extension brings software-style development to a class of applications that were once only possible with hardware
Load-Balancing for Parallel Delaunay Triangulations
Computing the Delaunay triangulation (DT) of a given point set in
is one of the fundamental operations in computational geometry.
Recently, Funke and Sanders (2017) presented a divide-and-conquer DT algorithm
that merges two partial triangulations by re-triangulating a small subset of
their vertices - the border vertices - and combining the three triangulations
efficiently via parallel hash table lookups. The input point division should
therefore yield roughly equal-sized partitions for good load-balancing and also
result in a small number of border vertices for fast merging. In this paper, we
present a novel divide-step based on partitioning the triangulation of a small
sample of the input points. In experiments on synthetic and real-world data
sets, we achieve nearly perfectly balanced partitions and small border
triangulations. This almost cuts running time in half compared to
non-data-sensitive division schemes on inputs exhibiting an exploitable
underlying structure.Comment: Short version submitted to EuroPar 201
Synthesis and Bulk Properties of Oxychloride Superconductor Ca2-xNaxCuO2Cl2
Polycrystalline samples and submillimeter size single crystals of Na-doped
Ca2CuO2Cl2 have been synthesized under high pressure. A series of experiments
showed that the Na content depends not only on the pressure during the
synthesis but also on the synthesis temperature and time. From a comparison of
the Na-CCOC data with those of structurally related La214 cuprate
superconductors we concluded that chlorine at the apical site is less effective
that oxygen in supplying charge carriers to the CuO2 plans. As a result, the
coupling between the CuO2 planes is weakened, the transition temperature Tc is
reduced and the anisotropic nature is enhanced.Comment: 7 pages, 7 figures, 1 table, presenthed at the Eucas 2007 conference.
Accepted for "Journal of Physics: Conference Series (JPCS)" 2008 and European
News Forum, Issue 3 (2008
Exponential speed-up with a single bit of quantum information: Testing the quantum butterfly effect
We present an efficient quantum algorithm to measure the average fidelity
decay of a quantum map under perturbation using a single bit of quantum
information. Our algorithm scales only as the complexity of the map under
investigation, so for those maps admitting an efficient gate decomposition, it
provides an exponential speed up over known classical procedures. Fidelity
decay is important in the study of complex dynamical systems, where it is
conjectured to be a signature of quantum chaos. Our result also illustrates the
role of chaos in the process of decoherence.Comment: 4 pages, 2 eps figure
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