Complex networks: new trends for the analysis of brain connectivity

Today, the human brain can be studied as a whole. Electroencephalography, magnetoencephalography, or functional magnetic resonance imaging techniques provide functional connectivity patterns between different brain areas, and during different pathological and cognitive neuro-dynamical states. In this Tutorial we review novel complex networks approaches to unveil how brain networks can efficiently manage local processing and global integration for the transfer of information, while being at the same time capable of adapting to satisfy changing neural demands.Comment: Tutorial paper to appear in the Int. J. Bif. Chao

Ten systemic steps for sustainable energy savings in small and medium enterprises

Energy savings are a priority in the different industrial sectors including Small and Medium Enterprises (SMEs). They have a conceptual perception of energy savings by replacing their service and production technologies with more efficient one. However, this technological change requires large-scale investment. There is another approach that can be used to reduce energy costs that has less impact on company production costs and does not require investments in technology. This approach considers planning and control procedures, which are considered in the present study. This study proposes a new method consisting of 10 systematic steps to achieve energy savings in SMEs. This method initially evaluates when, how, and where the energy is used, then identifies opportunities to achieve sustainable energy savings. The method involves various activities including an assessment of energy efficiency based on final energy consumption, adjusting production plans with low energy consumption and costs, and monitoring the energy budget. Application of this methodology in SMEs can save energy around 5 − 20% over a period of 1 to 3 y with some very low payback periods of less than a year. Operational controls implementation in Significant Energy Uses (SEU) can save energy around 2 − 5% of the consumption, without requiring investment in technology

Identification of energy saving potential in steam boiler through an ISO 50001 standard

The energy performance of steam boilers, such as the efficiency and the evaporation ratio can decrease along time because of the poor combustion, heat transfer fouling, poor operation, and low maintenance rate. The energy indicators assessment allows to observe the abnormal operational deviations to implement corrective action, so it is necessary to find out the level of efficiency in real time to evaluate the thermal performance, which is an obligatory requirement to implement the energy management program in the industry. As a contribution in the area of energy efficiency in steam boilers, the results of an applied research are presented, where the behavior of steam production and gas consumption as input variables were considered to apply the methodology and obtain the energy saving results on a boiler from 125.000lb/h steam capacity. The consumption and energy production control charts, the base and goal line, and base 100 indicators were calculated to facilitate the energy monitoring of the steam boiler for a period six month. Letting the application of the methodology to recognize saving opportunities starting from the analysis of variables that impact the energy consumption affected by different ways energy consumption of the company. The study showed a linear base with the form EB = 0.0595x + 0.988, with a linear correlation equal to R2 = 0.973 and a goal line EG = 0.0586x + 1.3814, with a linear correlation of R² = 0.97, which means statistical validity in the data collection. Additionally, the base 100 index was calculated to identify satisfactory the peaks of energy efficiency, showing efficiency and inefficiency in the process. The study shows that data reflected below the efficiency rate (100) are considered peaks of energy inefficiency, which means energy saving opportunities for operational control, maintenance management, production planning, besides the typical ones due to technological changes

Line and Continuum Variability in Active Galaxies

We compared optical spectroscopic and photometric data for 18 AGN galaxies over 2 to 3 epochs, with time intervals of typically 5 to 10 years. We used the Multi-Object Double Spectrograph (MODS) at the Large Binocular Telescope (LBT) and compared the spectra to data taken from the SDSS database and the literature. We find variations in the forbidden oxygen lines as well as in the hydrogen recombination lines of these sources. For 4 of the sources we find that, within the calibration uncertainties, the variations in continuum and line spectra of the sources are very small. We argue that it is mainly the difference in black hole mass between the samples that is responsible for the different degree of continuum variability. In addition we find that for an otherwise constant accretion rate the total line variability (dominated by the narrow line contributions) reverberates the continuum variability with a dependency $\Delta L_{line} \propto (\Delta L_{cont.})^{\frac{3}{2}}$. Since this dependency is prominently expressed in the narrow line emission it implies that the luminosity dominating part of the narrow line region must be very compact with a size of the order of at least 10 light years. A comparison to literature data shows that these findings describe the variability characteristics of a total of 61 broad and narrow line sources.Comment: 30 pages including the appendix, 18 figures including the appendix. Accepted 2015 September 3. Received 2015 August 24; in original form 2015 July 3 in Monthly Notices of the Royal Astronomical Societ

Techno-economic analysis of on-grid biomass renewable energy power station: A case study in Caribbean region of Colombia

In this article a techno-economic study of an Electric-Biomass on-grid power plant is presented, in order to compare the performance and the operating annual cost under some types of biogas produced from poultry, bovine and porcine manure, and solid urban organic waste, using the Homer® software to develop many solutions. Certainly, the best set up had the maximum combined renewable energy with a minimum electric consumption from the grid. The scheme was integrated by two 500kW biogas-powered electric generator on grid to supply an average energy of 1401.6kW, with an annual operating cost of $2.09 million when the energy supply is electric. Results presented a significant operational cost reduction when the biogas generator is operating on grid, finding an 8.61% of cost decrease using biogas generated from poultry, bovine and porcine manure, and a 10.53% of cost decrease using biogas from solid urban organic waste from centers and grocery market places at Caribbean Region of Colombia

Analysis and optimization for the process of glass tempering using autoclave

A mathematical analysis of the glass tempering process was carried out using an autoclave, varying the operating parameters of the system. It was found that the process time can be reduced by up to 3.23% by changing the resistance to 15Ω, but increasing the resistance more than this value would mean compromising the quality of the final product. Thus, it is advisable to make variations of the resistance between 10Ω and15Ω, which will allow the optimization of the process time and pressures without affecting the quality of the resul

Bibliometric study of state observer research applied to internal combustion engine

The present study was conducted to evaluate the worldwide scientific production related to observers applied to internal combustion engines by taking information from the Web of Science (WoS) database and taking the papers published between 2001 − 2017. The works found are mostly research articles with a total of 130 articles equivalent to 97.01%, of the 134 articles studied, and it was also noted that the production of this type of work increased in the last 3 years, with the maximum value in 2015 being 22 articles, even in those 3 years, the greatest number of references were also found. The United States is the country with the highest number of publications with 42 followed by People´s Republic of China, France and UK with 41, 11 and 11 respectively. Although the USA is the country with the highest number of publications, China has consolidated its position as the country with the highest number of publications and citations in the last 3 years. However, within the top 10 institutes with the highest number of publications, 4 of them are from the United States, among which Ohio State University stands out as the institute with the highest number of publications with 16 (11.9%). On the other hand, the most commonly used words in the documents were observer (91), control (47), engine (47), based (42) and estimation (41)

PEST analysis of wind energy in the world: From the worldwide boom to the emergent in Colombia

This article presents the analysis of the political, economic, social and technological aspects of the countries with the greatest development and generation of wind energy in the world, with the aim of studying the successes and disadvantages over the years and serve as a reference to a country like Colombia, which is in full technological development and is very interested in investing in new alternatives to the imminent ecological disaster resulting from polluting emissions. Colombia signs the Paris Agreement and immediately creates a large number of opportunities supported by state policies and economic investment, specifically in the construction of wind farms that guarantee a real alternative to the country's energy demand. Wind energy supplies 5% of the world's electricity, a contribution in which countries such as the United States, China, and Germany are the main producers. For this reason, it is necessary to study and analyze the factors that prevent the technological development of wind energy in Colombia, if it is considered a country with abundant resources in renewable energy sources and zero cost, a country that aspires to be a protagonist in the next 5 years according to the Ministry of Mines and Energy

Articulation of environmental management in projects of non-conventional energy sources in the Caribbean Colombian region

This work addresses an inclusion methodology based on criteria for the implementation of non-conventional energy sources and critical environmental factors for the licensing of the same, which is applied to the case study installation of wind turbines in seawater desalination plants in Isla Grande - Bolívar, this study was carried out taking into account field visits, and previous studies, where its main researchers and observers coincide with the authors of this article, the proposal includes aspects that involve the matrix of project stakeholders, work is completed with the qualitative and quantitative analysis of the factors of greater environmental impact, within the obtained results it is emphasized that the greatest impact that this project makes to 170 habitants of Isla Grande Bolivar is the changes of the current and/or potential use of soil, soil contamination and displacement of birds, In mammal, reptile and amphibian communities, it is suggested that Environmental Management Plans (PMA) be implemented, such as programs for conservation management, soil resource management, and vegetation and wildlife management programs, allowing for effective licensing of the project benefiting equally the interest group