Which Surrogate Works for Empirical Performance Modelling? A Case Study with Differential Evolution

It is not uncommon that meta-heuristic algorithms contain some intrinsic parameters, the optimal configuration of which is crucial for achieving their peak performance. However, evaluating the effectiveness of a configuration is expensive, as it involves many costly runs of the target algorithm. Perhaps surprisingly, it is possible to build a cheap-to-evaluate surrogate that models the algorithm's empirical performance as a function of its parameters. Such surrogates constitute an important building block for understanding algorithm performance, algorithm portfolio/selection, and the automatic algorithm configuration. In principle, many off-the-shelf machine learning techniques can be used to build surrogates. In this paper, we take the differential evolution (DE) as the baseline algorithm for proof-of-concept study. Regression models are trained to model the DE's empirical performance given a parameter configuration. In particular, we evaluate and compare four popular regression algorithms both in terms of how well they predict the empirical performance with respect to a particular parameter configuration, and also how well they approximate the parameter versus the empirical performance landscapes

A 3D assessment and feedback tool for Ankylosing Spondylitis from the perspective of healthcare professionals

To investigate the utility of 3D visualization technology to augment assessment and feedback for Ankylosing Spondylitis (AS), a visualization prototype was developed, and both subjective and objective measures of current assessment instruments were compared. To verify and establish a base-line for the prototype’s effectiveness, motion data and measurement data from a healthy adult in a laboratory environment were collected. To validate the prototype, a qualitative evaluation was undertaken using multiple methods including a pilot study, focus groups, and individual interviews. Research subjects comprised physiotherapists in clinical practice and academia and content analysis of their responses was used to substantiate the findings. The prototype enhanced both assessment and feedback of AS from the physiotherapist’s perspective and they believed it to be superior to the current methods used in practice for assessing the condition and in documenting variations for subsequent treatment. The physiotherapists believed that such a system had potential to encourage multidisciplinary working, and to be patient-centric, both with respect to the process of treatment and with regard to the convenience it offered to patients in managing their own condition. 3D visualization of AS symptoms and its treatment via exercise is a valuable technique as demonstrated by the prototype system

Improved detection of small atom numbers through image processing

We demonstrate improved detection of small trapped atomic ensembles through advanced post-processing and optimal analysis of absorption images. A fringe removal algorithm reduces imaging noise to the fundamental photon-shot-noise level and proves beneficial even in the absence of fringes. A maximum-likelihood estimator is then derived for optimal atom-number estimation and is applied to real experimental data to measure the population differences and intrinsic atom shot-noise between spatially separated ensembles each comprising between 10 and 2000 atoms. The combined techniques improve our signal-to-noise by a factor of 3, to a minimum resolvable population difference of 17 atoms, close to our ultimate detection limit.Comment: 4 pages, 3 figure

CAutoCSD-evolutionary search and optimisation enabled computer automated control system design

This paper attempts to set a unified scene for various linear time-invariant (LTI) control system design schemes, by transforming the existing concept of 'Computer-Aided Control System Design' (CACSD) to the novel 'Computer-Automated Control System Design' (CAutoCSD). The first step towards this goal is to accommodate, under practical constraints, various design objectives that are desirable in both time and frequency-domains. Such performance-prioritised unification is aimed to relieve practising engineers from having to select a particular control scheme and from sacrificing certain performance goals resulting from pre-committing to the adopted scheme. With the recent progress in evolutionary computing based extra-numeric, multi-criterion search and optimisation techniques, such unification of LTI control schemes becomes feasible, analytically and practically, and the resultant designs can be creative. The techniques developed are applied to, and illustrated by, three design problems. The unified approach automatically provides an integrator for zero-steady state error in velocity control of a DC motor, meets multiple objectives in designing an LTI controller for a non-minimum phase plant and offers a high-performing LTI controller network for a nonlinear chemical process

SCOOTER: A compact and scalable dynamic labeling scheme for XML updates

Although dynamic labeling schemes for XML have been the focus of recent research activity, there are significant challenges still to be overcome. In particular, though there are labeling schemes that ensure a compact label representation when creating an XML document, when the document is subject to repeated and arbitrary deletions and insertions, the labels grow rapidly and consequently have a significant impact on query and update performance. We review the outstanding issues todate and in this paper we propose SCOOTER - a new dynamic labeling scheme for XML. The new labeling scheme can completely avoid relabeling existing labels. In particular, SCOOTER can handle frequently skewed insertions gracefully. Theoretical analysis and experimental results confirm the scalability, compact representation, efficient growth rate and performance of SCOOTER in comparison to existing dynamic labeling schemes

Adapting the rice crop to hotter environments: Current and future activities at IRRI

Future climate scenarios are claiming for an increase in global temperature of 2 to 4°C by 2100 in the rice production areas in Asia One of the mandates of the International Rice Research Institute is to predict to what extent the different rice growing areas will be affected, tu analyze consequences on rice production and to provide adaptive strategies. A regional assessment of vulnerability to heat has been conducted by lRRl scientists on rice cropping areas by linking ORYZA2000 with Geographic Information System (GIS). The establishment of a spatio-temporal geo-statistical framework will soon allow identifying regions of risks of heat induced sterility, for which the threshold panicle temperature commonly ranges from 35 to 38°C with respect to the variety. To face this major issue, lRRl scientists are conducting multi-location testing of promising varieties and developing new genetic materials by screening donors from gene bank accessions. Some heat tolerance breeding populations have been developed and dispatched for hotspot screening, and 4 QTL mapping populations have been developed for polymorphism characterization. In addition, anthers of 3 lines contrasted for heat induced sterility were extracted, and some candidate genes are currently being sequenced and will be targeted for transformation. Donors for earlier time of the day of anthesis are investigated for heat induced sterility avoidance: 42 lines among 4000 from the lRRl gene bank accessions appeared to have peaked by 9am and were sent for testing in 5 Asian countries. An integrated phenotyping study for earlier time of the day of anthesis, heat tolerance to sterility and heat tolerance to chalkiness during grain filling, is actually conducted on a set of 212 contrasted accessions in the phytotron. Indeed, lRRl scientists demonstrated under plant temperatures higher than 30°C that genotypes that did not adapt to high temperature produced chalky grains whereas those that sacrificed part of their sink size maintained high quality grains. Similarly, such temperature regimes affect plant growth processes also at earlier stages like for leaf elongation rate. In the case of addressing confounding effects of climatic factors, the correlation observed during the last 15 years in the lRRl farm between the increase in night time temperature from 22 to 24°C and the reduction in grain yield is now confronted with additional data collected in a contrasted night temperature setup in the field. In collaboration with lRRl, scientists from Cirad and NIAES are collecting data in various field environments to quantify panicle temperature and predict its variation with regard to weather conditions, crop architecture and plant cooling ability. At the same time, lRRl scientists are developing the energy balance and exchange routines of OR YZA2000 and adding routines for canopy temperature and spikelet sterility. Considering rice is often grown in humid environments and soon under doubling air [C02], additional routines addressing interactions between temperature, humidity and [C02] will be developed by lRRl collaborators and included into crop models. Such cumulated efforts from rice scientists are necessary to face the challenges of future climate scenarios and make the rice production systems more resilient. (Texte intégral

Enabling internal electronic circuitry within additively manufactured metal structures - The effect and importance of inter-laminar topography

Purpose: This paper aims to explore the potential of ultrasonic additive manufacturing (UAM) to incorporate the direct printing of electrical materials and arrangements (conductors and insulators) at the interlaminar interface of parts during manufacture to allow the integration of functional and optimal electrical circuitries inside dense metallic objects without detrimental effect on the overall mechanical integrity. This holds promise to release transformative device functionality and applications of smart metallic devices and products. Design/methodology/approach: To ensure the proper electrical insulation between the printed conductors and metal matrices, an insulation layer with sufficient thickness is required to accommodate the rough interlaminar surface which is inherent to the UAM process. This in turn increases the total thickness of printed circuitries and thereby adversely affects the integrity of the UAM part. A specific solution is proposed to optimise the rough interlaminar surface through deforming the UAM substrates via sonotrode rolling or UAM processing. Findings: The surface roughness (Sa) could be reduced from 4.5 to 4.1 µm by sonotrode rolling and from 4.5 to 0.8 µm by ultrasonic deformation. Peel testing demonstrated that sonotrode-rolled substrates could maintain their mechanical strength, while the performance of UAM-deformed substrates degraded under same welding conditions ( approximately 12 per cent reduction compared with undeformed substrates). This was attributed to the work hardening of deformation process which was identified via dual-beam focussed ion beam–scanning electron microscope investigation. Originality/value: The sonotrode rolling was identified as a viable methodology in allowing printed electrical circuitries in UAM. It enabled a decrease in the thickness of printed electrical circuitries by ca. 25 per cent

Endogenous BDNF augments NMDA receptor phosphorylation in the spinal cord via PLCγ, PKC, and PI3K/Akt pathways during colitis

Background Spinal central sensitization is an important process in the generation and maintenance of visceral hypersensitivity. The release of brain-derived neurotrophic factor (BDNF) from the primary afferent neurons to the spinal cord contributes to spinal neuronal plasticity and increases neuronal activity and synaptic efficacy. The N-Methyl-D-aspartic acid (NMDA) receptor possesses ion channel properties, and its activity is modulated by phosphorylation of its subunits including the NMDA receptor 1 (NR1). Methods Colonic inflammation was induced by a single dose of intracolonic instillation of tri-nitrobenzene sulfonic acid (TNBS). NR1 phosphorylation by BDNF in vivo and in culture was examined by western blot and immunohistochemistry. Signal transduction was studied by direct examination and use of specific inhibitors. Results During colitis, the level of NR1 phospho-Ser896 was increased in the dorsal horn region of the L1 and S1 spinal cord; this increase was attenuated by injection of BDNF neutralizing antibody to colitic animals (36 μg/kg, intravenous (i.v.)) and was also reduced in BDNF+/− rat treated with TNBS. Signal transduction examination showed that the extracellular signal-regulated kinase (ERK) activation was not involved in BDNF-induced NR1 phosphorylation. In contrast, the phosphatidylinositol 3-kinase (PI3K)/Akt pathway mediated BDNF-induced NR1 phosphorylation in vivo and in culture; this is an additional pathway to the phospholipase C-gamma (PLCγ) and the protein kinase C (PKC) that was widely considered to phosphorylate NR1 at Ser896. In spinal cord culture, the inhibitors to PLC (U73122), PKC (bisindolylmaleimide I), and PI3K (LY294002), but not MEK (PD98059) blocked BDNF-induced NR1 phosphorylation. In animals with colitis, treatment with LY294002 (50 μg/kg, i.v.) blocked the Akt activity as well as NR1 phosphorylation at Ser896 in the spinal cord. Conclusion BDNF participates in colitis-induced spinal central sensitization by up-regulating NR1 phosphorylation at Ser896. The PI3K/Akt pathway, in addition to PLCγ and PKC, mediates BDNF action in the spinal cord during colitis

Quantum correlations in a cluster-like system

We discuss a cluster-like 1D system with triplet interaction. We study the topological properties of this system. We find that the degeneracy depends on the topology of the system, and well protected against external local perturbations. All these facts show that the system is topologically ordered. We also find a string order parameter to characterize the quantum phase transition. Besides, we investigate two-site correlations including entanglement, quantum discord and mutual information. We study the different divergency behaviour of the correlations. The quantum correlation decays exponentially in both topological and magnetic phases, and diverges in reversed power law at the critical point. And we find that in TQPT systems, the global difference of topology induced by dimension can be reflected in local quantum correlations.Comment: 7 pages, 6 figure