What can we learn from multi-objective meta-optimization of Evolutionary Algorithms in continuous domains?

Properly configuring Evolutionary Algorithms (EAs) is a challenging task made difficult by many different details that affect EAs' performance, such as the properties of the fitness function, time and computational constraints, and many others. EAs' meta-optimization methods, in which a metaheuristic is used to tune the parameters of another (lower-level) metaheuristic which optimizes a given target function, most often rely on the optimization of a single property of the lower-level method. In this paper, we show that by using a multi-objective genetic algorithm to tune an EA, it is possible not only to find good parameter sets considering more objectives at the same time but also to derive generalizable results which can provide guidelines for designing EA-based applications. In particular, we present a general framework for multi-objective meta-optimization, to show that "going multi-objective" allows one to generate configurations that, besides optimally fitting an EA to a given problem, also perform well on previously unseen ones

An Application Of Artificial Immune System In A Wastewater Treatment Plant

Guaranteeing the continuity and the quality of services in network plants is a key issue in the research area of asset management. Especially when the plants are located in a wide area where machines are not continuously monitored by the operators. In particular, the pervasive adoption of smart sensors could be able to develop intelligent maintenance system through an elaboration of data coming from the machines: this data could be processed by diagnostics algorithms to warn preventively the fault status of the components or machines monitored. The algorithms’ structure is contained in a multiple system of agents that have different tasks to manage both the single machine and the information exchanged within the whole system. This paper aims to present an application of Artificial Immune System defining, for each plant section, the kind of agents employed and the related sensors that must be adopted to collect the useful data. In order to provide a practical example, the structure of an Artificial Immune System has been implemented in a wastewater treatment plant where the agents are tested with noteworthy results. © 20164928556

Bending and shear behavior of historic walls strengthened with composite reinforced mortar

Composite reinforced mortar (CRM) is a relatively new solution for the strengthening of existing masonry members that comprises fiber-reinforced polymer (FRP) grids reinforcing inorganic mortar overlays. CRMs were proven to be effective in strengthening masonry members against in- and out-of- plane loads. In this paper, a glass FRP-CRM is employed to strengthen 5-leaf historic masonry walls cut from an existing building located in Milan, Italy. The walls were strengthened and then subjected to three-point bending and diagonal compression tests. Results were compared with those of corresponding non-strengthened walls and showed the CRM effectiveness also in the case of thick masonry members

Emotion-based analysis of programming languages on Stack Overflow

When developing a software engineering project, selecting the most appropriate programming language is a crucial step. Most often, feeling at ease with the possible options becomes almost as relevant as the technical features of the language. Therefore, it appears to be worth analyzing the role that the emotional component plays in this process. In this article, we analyze the trend of the emotions expressed by developers in 2018 on the Stack Overflow platform in posts concerning 26 programming languages. To do so, we propose a learning model trained by distant supervision and the comparison of two different classifier architectures

Effect of cyclic load on the tensile behavior of a PBO FRCM composite

The use of externally bonded fiber-reinforced cementitious matrix (FRCM) composites represents a valid alternative to traditional techniques for the strengthening and retrofitting of existing reinforced concrete and masonry structures. FRCM composites are comprised of high strength textiles embedded within inorganic matrices and can be directly applied to the external surface of the existing structural element to increase its displacement and load capacity (i.e., axial, flexural, and shear strength). Thus, FRCM have a low invasiveness and a high strength-to-weight ratio. Recently, investigations on the bond behavior of FRCM composites showed that the presence of friction between the textile and matrix can induce damage to the fiber, which in turn determines possible reductions in the strengthened element capacity. This effect appears particularly critical in the case of cyclic and dynamic loads. In this paper, the cyclic behavior of a PBO FRCM composite is experimentally investigated using low-cycle tensile tests on composite specimens. Namely, FRCM rectangular coupons are subjected to clamping- and clevis-grip tensile tests. These tests provide important information on the effect of low-frequency dynamic loading on the composite tensile properties under different test configurations

1WGAJ1226.9+3332: a high redshift cluster discovered by Chandra

We report the detection of 1WGAJ1226.9+3332 as an arcminute scale extended X-ray source with the Chandra X-ray Observatory. The Chandra observation and R and K band imaging strongly support the identification of 1WGAJ1226.9+3332 as a high redshift cluster of galaxies, most probably at z=0.85 +- 0.15, with an inferred temperature kT =10 (+4;-3) keV and an unabsorbed luminosity (in a r=120" aperture) of 1.3 (+0.16;-0.14) x 1e45 erg/s (0.5-10 keV). This indication of redshift is also supported by the K and R band imaging, and is in agreement with the spectroscopic redshift of 0.89 found by Ebeling et al. (2001). The surface brightness profile is consistent with a beta-model with beta=0.770 +- 0.025, rc=(18.1 +-0.9)" (corresponding to 101 +- 5 kpc at z=0.89), and S(0)=1.02 +- 0.08 counts/arcsec**2. 1WGAJ1226.9+3332 was selected as an extreme X-ray loud source with FX/FV>60; this selection method, thanks to the large area sampled, seems to be a highly efficient method for finding luminous high z clusters of galaxies.Comment: 5 pages, 5 figures, 1 table. Accepted for publication in ApJ main journal. Uses emulateapj.st

Persistent and Transient Blank Field Sources

Blank field sources (BFS) are good candidates for hosting dim isolated neutron stars (DINS). The results of a search of BFS in the ROSAT HRI images are revised. We then focus on transient BFS, arguing that they belong to a rather large population. The perspectives of future research on DINS are then discussed.Comment: 3 pages, 0 figures. Paper presented at the Conference "Isolated Neutron Stars: from the interior to the surface", London, April 2006. Astrophysics and Space Science, in pres