67 research outputs found
Central Asia Forecasting 2021: Results from an Expert Survey
The 'Central Asia Forecasting' study, jointly implemented by the Friedrich Ebert Foundation (FES), the OSCE Academy in Bishkek, and the SPCE Hub, aims to help strengthen EU-Central Asia relations. The study results are intended to stimulate the debate on the region, foster understanding of the common challenges and opportunities, and encourage data-driven policymaking. It is a pilot project that will be followed by an annual or biennial study to analyse regional trends over time. The audience that we aim to address with this report comprises the broader public in Europe and Central Asia, civil society representatives, regional experts, researchers and especially EU foreign-policy makers. For this study, a human-judgement forecasting method was employed in the form of an opinion survey among experts and the informed public on developments in the region in the next three years. In total, 144 respondents took our 20-minute survey. About half of the respondents are Central Asian citizens and half are from outside the region. The majority are affiliated with academic institutions and think tanks. This report launch will present the analysis of the survey responses regarding domestic politics and regional affairs, global challenges affecting the region, and EU-Central Asian relations
Towards hardware acceleration of neuroevolution for multimedia processing applications on mobile devices
This paper addresses the problem of accelerating large artificial neural networks (ANN), whose topology and weights can evolve via the use of a genetic algorithm. The proposed digital hardware architecture is capable of processing any evolved network topology, whilst at the same time providing a good trade off between throughput, area and power consumption. The latter is vital for a longer battery life on mobile devices. The architecture uses multiple parallel arithmetic units in each processing element (PE). Memory partitioning and data caching are used to minimise the effects of PE pipeline stalling. A first order minimax polynomial approximation scheme, tuned via a genetic algorithm, is used for the activation function generator. Efficient arithmetic circuitry, which leverages modified Booth recoding, column compressors and carry save adders, is adopted throughout the design
Analysing co-evolution among artificial 3D creatures
This paper is concerned with the analysis of coevolutionary dynamics among 3D artificial creatures, similar to those introduced by Sims (1). Coevolution is subject to complex dynamics which are notoriously difficult to analyse. We introduce an improved analysis method based on Master Tournament matrices [2], which we argue is both less costly to compute and more informative than the original method. Based on visible features of the resulting graphs, we can identify particular trends and incidents in the dynamics of coevolution and look for their causes. Finally, considering that coevolutionary progress is not necessarily identical to global overall progress, we extend this analysis by cross-validating individuals from different evolutionary runs, which we argue is more appropriate than single-record analysis method for evaluating the global performance of individuals
Neuroevolutionary reinforcement learning for generalized control of simulated helicopters
This article presents an extended case study in the application of neuroevolution to generalized simulated helicopter hovering, an important challenge problem for reinforcement learning. While neuroevolution is well suited to coping with the domain’s complex transition dynamics and high-dimensional state and action spaces, the need to explore efficiently and learn on-line poses unusual challenges. We propose and evaluate several methods for three increasingly challenging variations of the task, including the method that won first place in the 2008 Reinforcement Learning Competition. The results demonstrate that (1) neuroevolution can be effective for complex on-line reinforcement learning tasks such as generalized helicopter hovering, (2) neuroevolution excels at finding effective helicopter hovering policies but not at learning helicopter models, (3) due to the difficulty of learning reliable models, model-based approaches to helicopter hovering are feasible only when domain expertise is available to aid the design of a suitable model representation and (4) recent advances in efficient resampling can enable neuroevolution to tackle more aggressively generalized reinforcement learning tasks
Barium in twilight zone suspended matter as a potential proxy for particulate organic carbon remineralization : results for the North Pacific
Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 55 (2008): 1673-1683, doi:10.1016/j.dsr2.2008.04.020.This study focuses on the fate of exported organic carbon in the twilight zone at two
contrasting environments in the North Pacific: the oligotrophic ALOHA site (22°45'
N 158°W; Hawaii; studied during June–July 2004) and the mesotrophic Subarctic
Pacific K2 site (47°N, 161°W; studied during July-August 2005). Earlier work has
shown that non-lithogenic, excess particulate Ba (Baxs) in the mesopelagic water
column is a potential proxy of organic carbon remineralization. In general Baxs
contents were significantly larger at K2 than at ALOHA. At ALOHA the Baxs profiles
from repeated sampling (5 casts) showed remarkable consistency over a period of
three weeks, suggesting that the system was close to being at steady state. In contrast,
more variability was observed at K2 (6 casts sampled) reflecting the more dynamic
physical and biological conditions prevailing in this environment. While for both sites
Baxs concentrations increased with depth, at K2 a clear maximum was present
between the base of the mixed layer at around 50m and 500m, reflecting production
and release of Baxs. Larger mesopelagic Baxs contents and larger bacterial production
in the twilight zone at the K2 site indicate that more material was exported from the
upper mixed layer for bacterial degradation deeper, compared to the ALOHA site.
Furthermore, application of a published transfer function (Dehairs et al., 1997)
relating oxygen consumption to the observed Baxs data indicated that the latter were in
good agreement with bacterial respiration, calculated from bacterial production. These
results corroborate earlier findings highlighting the potential of Baxs as a proxy for
organic carbon remineralization.
The range of POC remineralization rates calculated from twilight zone excess
particulate Ba contents did also compare well with the depth dependent POC flux
decrease as recorded by neutrally buoyant sediment traps, except in 1 case (out of 4).
This discrepancy could indicate that differences in sinking velocities cause an
3
uncoupling of the processes occurring in the fine suspended particle pool from those
affecting the larger particle pool which sustains the vertical flux, thus rendering
comparison between both approaches risky.This research was supported by Federal Science Policy
Office, Brussels through contracts EV/03/7A, SD/CA/03A, the Research Foundation
Flanders through grant G.0021.04 and Vrije Universiteit Brussel via grant GOA 22, as
well as the US National Science Foundation programs in Chemical and Biological
Oceanography
Particle fluxes associated with mesoscale eddies in the Sargasso Sea
Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 55 (2008): 1426-1444, doi:10.1016/j.dsr2.2008.02.007.We examined the impact of a cyclonic eddy and mode-water eddy on particle flux in the
Sargasso Sea. The primary method used to quantify flux was based upon measurements of the
natural radionuclide, 234Th, and these flux estimates were compared to results from sediment
traps in both eddies, and a 210Po/210Pb flux method in the mode-water eddy. Particulate organic
carbon (POC) fluxes at 150m ranged from 1 to 4 mmol C m-2 d-1 and were comparable between
methods, especially considering differences in integration times scales of each approach. Our
main conclusion is that relative to summer mean conditions at the Bermuda Atlantic Time-series
Study (BATS) site, eddy-driven changes in biogeochemistry did not enhance local POC fluxes
during this later, more mature stage of the eddy life cycle (>6 months old). The absence of an
enhancement in POC flux puts a constraint on the timing of higher POC flux events, which are
thought to have caused the local O2 minima below each eddy, and must have taken place >2
months prior to our arrival. The mode-water eddy did enhance preferentially diatom biomass in
its center where we estimated a factor of 3 times higher biogenic Si flux than the BATS summer
average. An unexpected finding in the highly depth resolved 234Th data sets are narrow layers of
particle export and remineralization within the eddy. In particular, a strong excess 234Th signal is
seen below the deep chlorophyll maxima which we attribute to remineralization of 234Th bearing
particles. At this depth below the euphotic zone, de novo particle production in the euphotic
zone has stopped, yet particle remineralization continues via consumption of labile sinking
material by bacteria and/or zooplankton. These data suggest that further study of processes in
ocean layers is warranted not only within, but below the euphotic zone.The EDDIES project was funded by the National Science Foundation Chemical, Biological, and
Physical Oceanography Programs. Additional support for HPLC pigment analysis (Dr. Charles
Trees, CHORS) was provided by NASA
Experiments on neuroevolution and online weight adaptation in complex environments
Neuroevolution has come a long way over the last decade. Lots of interesting and successful new methods and algorithms have been presented, with great improvements that make the field become very promising. Concretely, HyperNEAT has shown a great potential for evolving large scale neural networks, by discovering geometric regularities, thus being suitable for evolving complex controllers. However, once training phase has finished, evolved neural networks stay fixed and learning/adaptation does not happen anymore. A few methods have been proposed to address this concern, mainly using Hebbian plasticity and/or Compositional Pattern Producing Networks (CPPNs) like in Adaptive HyperNEAT. This methods have been tested in simple environments to isolate the effectiveness of adaptation from the Neuroevolution. In spite of this being quite convenient, more research is needed to better understand online adaptation in more complex environments. This paper shows a new proposal for online weight adaptation in neuroevolved artificial neural networks, and presents the results of several experiments carried out in a race simulation environment
Evolving A Single Scalable Controller For An Octopus Arm With A Variable Number Of Segments
While traditional approaches to machine learning are sensitive to high-dimensional state and action spaces, this paper demonstrates how an indirectly encoded neurocontroller for a simulated octopus arm leverages regularities and domain geometry to capture underlying motion principles and sidestep the superficial trap of dimensionality. In particular, controllers are evolved for arms with 8, 10, 12, 14, and 16 segments in equivalent time. Furthermore, when transferred without further training, solutions evolved on smaller arms retain the fundamental motion model because they simply extend the general kinematic concepts discovered at the original size. Thus this work demonstrates that dimensionality can be a false measure of domain complexity and that indirect encoding makes it possible to shift the focus to the underlying conceptual challenge. © 2010 Springer-Verlag
- …