An energy management system for cluster infrastructures

This paper presents a general energy management system for High Performance Computing (HPC) clusters and cloud infrastructures that powers off cluster nodes when they are not being used, and conversely powers them on when they are needed. This system can be integrated with different HPC cluster middleware, such as Batch-Queuing Systems or Cloud Management Systems, and can also use different mechanisms for powering on and off the computing nodes. The presented system makes it possible to implement different energy-saving policies depending on the priorities and particularities of the cluster. It also provides a hook system to extend the functionality, and a sensor system in order to take into account environmental information.     

A simple empirical method for estimating surface water vapour pressure using MODIS near-infrared channels: applications to northern Spain's Asturias region

In this article, we present a simple methodology for obtaining algorithms to estimate surface water vapour pressure (e ₀) over cloud-free land areas using Moderate Resolution Imaging Spectroradiometer (MODIS) data. The algorithm obtained in this case is adapted to the particular climatic characteristics of the Asturias region, but the methodology can easily be extrapolated and used to obtain algorithms for other regions around the world. The proposed method estimates e ₀ from a simple linear combination of the radiances of the MODIS near-infrared (NIR) channels more commonly applied to total precipitable water (W) estimations. Comparison between the e ₀ data measured at the ground-based meteorological stations in Asturias (daily data from 2004) versus the values predicted using the proposed algorithm gives R ² = 0.76 and residual standard error (RSE) = 2.07 hPa (16%). The algorithm was tested using the data from 2008 obtained in Asturias and in two sites outside of Asturias with similar latitudes and radiosonde observations (La Coruña and Santander). The resulting validation demonstrates that the algorithm gives good results in Asturias (root-mean-square deviation (RMSD) = 2.50 hPa (19%) and bias = 1.26 hPa, with R ² = 0.65) and when La Coruña is included (R ² = 0.61), but that its validity is decreased when Santander is also included (R ² = 0.56).

The possibility of obtaining e ₀ from three global MODIS algorithms for W retrieval was also tested and compared to our algorithm. The results show that our algorithm gives better results than the International MODIS/Atmospheric InfraRed Sounder Processing Package (IMAPP) Water Vapour Near-Infrared (WVNIR) product and the Sobrino algorithm. The MODIS Total Precipitable Water (MOD05) product is worse than that obtained with our algorithm in Asturias (R ² = 0.61 vs. R ² = 0.65), but the two values are similar if the stations in La Coruña (R ² = 0.60) and Santander (R ² = 0.56) are included in the comparison. The dominant advantage of the novel algorithm proposed in this study is that it is simpler and can be produced quickly in real time.     

Maximum likelihood estimation for the three-parameter Weibull cdf of strength in presence of concurrent flaw populations

For a correct strength characterization of brittle materials, not only the maximum stress at fracture, but also the geometry of the specimens has to be considered thus taking into account the variable stress state and the size effect. Additionally, fracture may occur due to different fracture modes, as for example surface or edge defects. The authors propose a maximum likelihood estimator to obtain the cumulative distribution functions of strength for surface and edge flaw populations separately, both being three-parameter Weibull cdfs referred to an elemental surface area or elemental edge length, respectively. The method has been applied to simulated 3-point bending test data. The estimated Weibull parameters have been used to compute the cdfs of strength for specimens with different size, providing also the confidence bounds calculated by means of the bootstrap method. Finally, fracture data of 4-point bending tests on silicon carbide have been evaluated with the proposed method.     

A biokinematic approach for the computational simulation of proteins molecular mechanism

Proteins play an essential role in the biological processes that take place in the human body. For this reason, it is very important to understand the molecular mechanisms involved. Recently a new approach, based on the parallelism between proteins and spatial mechanisms, has allowed methods to be developed to obtain atomic trajectories for protein motion using concepts from the kinematics of mechanisms. This paper presents a method for simulating protein motion, based on the evaluation of the potential energy during the motion, thereby avoiding the need to perform a minimization procedure. This approach constitutes a good compromise between computational effort and accuracy of the results. In addition, in order to efficiently simulate the motion, a new algorithm for normalization of the structure of the protein is presented. Finally, we illustrate the results of applying this method to an inorganic pyrophosphatase (family II) from Streptococcus gordonii evaluating geometric accuracy, energetic evolution and biological indicators.     

On the power of elementary features in spiking neural P systems

Since their first publication in 2006, spiking neural (SN) P systems have already attracted the attention of a lot of researchers. This might be owing to the fact that this abstract computing device follows basic principles known from spiking neural nets, but its implementation is discrete, using membrane computing background. Among the elementary properties which confer SN P systems their computational power one can count the unbounded fan-in (indegree) and fan-out (outdegree) of each “neuron”, synchronicity of the whole system, the possibility of delaying and/or removing spikes in neurons, the capability of evaluating arbitrary regular expressions in neurons in constant time and some others. In this paper we focus on the power of these elementary features. Particularly, we study the power of the model when some of these features are disabled. Rather surprisingly, even very restricted SN P systems keep their universal computational power. Certain important questions regarding this topic still remain open.     

An assessment of discretizations for convection-dominated convection–diffusion equations

The performance of several numerical schemes for discretizing convection-dominated convection–diffusion equations will be investigated with respect to accuracy and efficiency. Accuracy is considered in measures which are of interest in applications. The study includes an exponentially fitted finite volume scheme, the Streamline-Upwind Petrov–Galerkin (SUPG) finite element method, a spurious oscillations at layers diminishing (SOLD) finite element method, a finite element method with continuous interior penalty (CIP) stabilization, a discontinuous Galerkin (DG) finite element method, and a total variation diminishing finite element method (FEMTVD). A detailed assessment of the schemes based on the Hemker example will be presented.     

Comparative evaluation of the olive oil given by a new processing system

To evaluate the level of quality of the olive oil given by a new processing system we compared it with the percolation oil, which is known to be of high quality. The new product was characterized by the following: (i) higher contents of tocopherols, tyrosol- and hydroxytyrosol-aglycones, volatile aromatic substances, sterols, triterpene alcohols and lipochromes, and higher values of 1,2-diglycerides/1,3-diglycerides and campesterol/stigmasterol ratios, colour indices and turbidity; (ii) lower contents of waxes and triterpene dialcohols, and lower values for spectrophotometric indices, carbonyl index, Wolff's ratio (K₂₃₂/K₂₇₀), acidity, and peroxide number; (iii) similar contents of phenols, o- diphenols, free tyrosol, free hydroxytyrosol, triglycerides, stigmastadienes, and aliphatic alcohols, similar sensory score, and similar value of resistance to autoxidation, alcohol index, overall quality indices, and fatty acid composition.     

Variations of iridoid oleuropein in Italian olive varieties during growth and maturation

This research paper reports on the concentrations of oleuropein in fruits of seven Italian olive cultivars. These oleuropein levels, during fruit growth and maturation, were monitored by taking olive samples from the same olive trees grown in Middle Italy. A novel high‐resolution gas chromatography (HRGC) oleuropein quantification method and a new high‐performance liquid chromatography (HPLC) method were developed. The olive fruits showed high contents of oleuropein, which were greatly influenced by the olive cultivar (genetic store) factor. The stage of fruit growth and maturation was another factor strongly affecting the contents of iridoid oleuropein in olive drupes, whatever the olive cultivar considered. Green olives had much higher concentrations of this biofunctional glucoside, which decreased regularly during fruit growth and ripeness. No differences were observed between the two developed oleuropein quantification methods, which gave, for all the olive cultivars, average values of fruit oleuropein contents that were not statistically different. These two reliable repetitive methods, noticeably the HPLC one (which also showed a lower running time), could be used for routine determination of oleuropein in olive drupes. We observed that, in general, olive cultivars having high oleuropein concentrations in the fruits were also characterized by marked oleuropein contents in the leaves.     

Estimation of dietary intake of pesticide residues by the Italian population during 1997

In 1997 the Italian monitoring programme for pesticide residues in food comprised 7951 samples of 152 different foods for which a total of 275 pesticides were analysed. For 90 pesticides, the National Estimated Daily Intakes (NEDIs) were calculated by using the 90th percentile value and the food consumption data for the general Italian population. The calculated NEDIs were found to represent only a small portion of the respective Acceptable Daily Intake (ADI).