Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The different alternatives used in the construction industry make that in the structural analysis and design several tools are used to know the correct behavior of the structures under different load states. Therefore, a study of the behavior of self-supporting flat roofs and their connection with lateral beams is presented by applying the finite element method within a linear analysis with the help of ANSYS Workbench software. For this purpose, an IMAP-800 section was used, forming roofs with spans of 10, 20, 30 and 40 m, complementing the analysis with lattice-type beams and columns. For the fastening support, a plate with thicknesses from 4 to 12 mm was used, to compare with national and international design guidelines, such as thickness, slope, maximum span and the geometry of the fastening support. Maximum stresses were observed near the fixing brackets, while maximum deformations took place at the ends of the roof. By setting new parameters to save the corresponding spans, it showed an increase in the roof weight of about 5% in relation to the design guidelines used.

Fault-induced delayed voltage recovery (FIDVR) is a major threat to the voltage stability of electrical power systems with load dominated by induction motors. Over the past decade, load rejection strategies have been proposed to mitigate FIDVR and avoid voltage instability. This paper analyzes the load shedding strategies published in the scientific literature to mitigate FIDVR. A classification of scientific publications based on a systematic method of evaluation of characteristics is applied, for which the characteristics of the strategies are identified according to their methodological and technological aspects of design and functionality; further the characteristics are evaluated according to their degree of belonging and with this the analyzed publications are classified. The result of the analysis of the load shedding strategies, based on empirical rules and analytical methods, revealed that they are not yet fully efficient in determining the minimum amount of load to be disconnected, nor fast enough to effectively reduce the voltage recovery time; and it is also found that design methods based on artificial intelligence represent a great opportunity to overcome these challenges.

Motivated by the global pandemic caused by Covid-19 during the years 2020 and 2021, scientific research and its dissemination in international journals were affected by the impact of this disease. This editorial reflects on the effects during those years considering some figures on published documents and journals indexed worldwide, in Latin America and in Venezuela, published in recognized scientific databases. The editorial work of scientific journals does not stop, even during the pandemic, and in the case of Venezuelan journals, although they were affected, they continue to fulfill their mission of scientific dissemination, especially through open access platforms.

Wastewater from the fishmeal production industry has a high content of organic matter, turbidity and fats, which makes its treatment and final disposal difficult. Therefore, this study focuses on evaluating the efficacy of coagulants of natural origin versus synthetic coagulants, as a function of turbidity and the factors that influence it by applying an experimental quantitative study. The natural coagulants used were Aloe vera gel and Selenicereus Undatus pitahaya mucilage, while the coagulants of chemical origin were aluminum polychloride (PAC) and aluminum sulfate. So that to the high concentration of fat present in the discharge water with respect to the reference value, a pre-sedimentation of the water was carried out without any type of mechanical or coagulating action, resulting in the elimination of fats of 92%.The initial turbidity of the wastewater was 1230.33 NTU, obtaining turbidity removal percentages for PAC, aluminum sulfate, pitahaya and Aloe vera in the order of 99.58%, 99.87%, 62.26%, 75.15%, respectively. On the other hand, the COD for the most efficient synthetic coagulant and natural coagulant, was 18 mgO2/L and 839.35 mgO2/ correspondingly. This study aims to promote the use of friendly resources for the environment, guaranteeing an efficient removal of contamination from the aqueous environment.

The article presents the findings of a systematic review immersed in the literature, focused on identifying the main elements of Technology Management in chemical industries. A total of 556 scientific articles were obtained using online scientific search engines. The analysis was exploratory/descriptive using the cocitation context analysis method, based on the perspective of the academic genealogy retrospective literature, statistics and distribution, making use of VOSviewer® co-occurrence to reflect the link chain of common thread, whose result denoted 30 binding terms to the study area, which are: Cost, gap, identification, implementation, improvement, policy, products, production, six sigma quality system, stakeholders, sustainable development, technique, capacity, collaboration, competitive advantages, customers, innovation, manufacturer, supplier, flexibility, integration, manufacturing companies, performance, relationships, supply chain management, adoption, data and uncertainty. In conclusion, the most relevant terms of Technology Management are obtained from the systematic review in the period 2011 to 2021, as well as these terms were grouped through data mining, obtaining 5 broadly defined clusters. Additionally, the main terms with propensity capacity and/or trends since 2018 are highlighted.

The Human Development Index (HDI) is a summary measure of the development level of each country. The objective of the research consists of an efficiency study applying Data Envelopment Analysis (DEA) and evaluating the relationship between “Fossil Energy Consumption” and “CO2 Emissions” with HDI in nine American countries with an installed hydroelectric generation capacity greater than 1000 megawatts (MW). Hydropower shows an opportunity to contribute positively to the HDI as an alternative means of electricity generation without the use of fossil fuels. HDI variable is used as the output and other two as inputs in the efficiency analysis using DEA. A total of six countries show a maximum efficiency of 100 %, with Mexico being the least efficient. In countries with less technical efficiency, it´s opportune to consider the reduction in the use of fossil fuels and establish mitigation measures in terms of CO2 emissions to improve the environment and increase human health, thus meaning an improvement in the HDI.

FIDVR represents a major threat to the safe and reliable operation of electrical power systems with load dominated induction motors. In this paper, a load shedding strategy based on the critical recovery time (CRT) of voltage is proposed to mitigate FIDVR. The CRT allows identify the most effective load mainly responsible for the FIDVR, while the CRT desviation determines the amount of load to be disconnected in each effective bus according to the severity of the FIDVR. The results obtained by simulating the strategy in the Power Factory DigSilent DPL on the 39 Bus New England system showed that it is capable of identifying the most effective location and amount of load to mitigate FIDVR. Compared with the conventional UVLS scheme, the proposed strategy achieves a fast voltage recovery and requires a smaller amount of load to be disconnected. It is concluded that the proposed load shedding strategy responds adaptively to the severity of the FIDVR to disconnect the minimum amount of load in order to improve short-term voltage stability.

Electricity generation in Venezuela is dominated by fossil fuels and large-scale hydroelectric plants, predominating over other energy sources. The objective of this research is to determine the solar photovoltaic and wind potential and to propose scenarios of hybrid electric energy systems for Toas Island, Zulia State. In the first part, a documentary research on this potential was carried out, then with data obtained from solar irradiation and wind speed, through Global Solar, NASA Power and the use of the Homer application, a feasible project of a micro grid applied to Toas Island, Almirante Padilla Municipality, Zulia State, was presented.  Thus demonstrating that the photovoltaic, wind, battery and interconnection scenario is the best applicable option, with a levelized cost of electricity of 0.3 $/kWh, offering greater reliability and availability, with the possibility of transmitting surpluses to the electric grid.

A super pressurized balloon is a sealed structure made of a thin linear low density polyethylene (LLDPE) membrane reinforced with cords, with tension calculated to counterbalance intense stresses on the film as shown in this paper. We propose a double super pressurized (DSP) balloon design, with an inner membrane inside a slightly larger one. Both membranes are connected by LLPDE films joining the cords of each balloon, creating gore-panels surrounding the internal membrane. The internal globe is filled with Hydrogen, that is inexpensive but inflammable while the external gores will be filled with nonflammable gas Helium, but very expensive. As volume of the internal globe is much larger than the volume of the exterior panels, the cost of filling this double balloon is drastically reduced, compared with traditional balloons completely filled with Helium. In the DSP balloon Hydrogen must go first through the exterior panels in order to escape, then the loss rate of Hydrogen is largely reduced, increasing the security in the use of Hydrogen filled balloons. Also, the double balloon can resist the breaking of the exterior membrane, even the rupture of the inner membrane provided they do not break in the same section.