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

The social, economic, and environmental consequences of the failure of an arch dam make it essential to evaluate its dynamic response to mitigate the risk of a disaster. Since the slenderness and flexibility of these dams tend to increase the fluid-structure interaction during an earthquake, this work compares the dynamic response of a hypothetical arch dam in the Marañón river, in northern Perú, for both full and empty-reservoir conditions. Three formulations were used to estimate the hydrodynamic pressures: Westergaard’s added mass, Eulerian and Lagrangian. The comparisons were performed for earthquakes of distinct seismogenic sources, previously matched to a uniform hazard spectrum with a return period of 10000 years. The finite element method was used to derive the seismic demands of the dam-reservoir-foundation system in COMSOL Multiphysics software, carrying out time-history analyses assuming linear elastic behavior of the dam and foundation domains and a massless foundation approach, ignoring the effect of waves propagation in the foundation but considering its stiffness. The results show that the Lagrangian and Eulerian formulations produce similar seismic demands, while Westergaard’s added mass formulation is conservative. The full-reservoir condition generally increases the seismic demands, but the results will depend on the boundary conditions assumed for the fluid and the characteristics of the earthquake, among other factors. Earthquakes matched to the same uniform hazard spectrum do not necessarily produce equal dynamic responses.

The collapse of some floor diaphragms during earthquakes was due to failures in connection with vertical elements or because those were not designed for seismic forces in its plane. This has made that the design of diaphragms is an issue that has been incorporated in many seismic codes. For its design, it is necessary the maximum acceleration on each floor during a strong seismic event. The seismic Peruvian code E.030 does not include any methodology about how to calculate those accelerations floor, it only refers to acceleration on floors but due to maximum base shear which does not correspond to maximum acceleration in each level. In this paper, a simplified procedure for obtaining maximum floor accelerations is shown. This procedure is based on First Mode Reduced method [1] to which a factor rW was included to consider higher modes participation in dual systems (frames / walls). The rW factor corresponds to the ratio of base moment in walls and base moment in the building. In the validation of the procedure, it was observed that the proposed procedure agrees with the results of experimental and analytical models.

This paper aims to study the efficiency of energy dissipators, both fluid viscous and hysteretic, to improve the seismic responses of buildings. To quantify the ability of energy dissipators to reduce seismic responses, a series of time history analyzes were carried out on simplified models of buildings. Said simplified models consist of masses and springs with linear and elastic behavior whose properties are obtained from a shear beam model, joined by link elements with non-linear behavior to simulate energy dissipators. The main study parameters that were considered are the fundamental period of the structure without seismic control devices and the objective reduction factor. Likewise, a procedure is proposed for the dimensioning of the hysteretic dampers that will be incorporated into a building. On the other hand, the main building of the Lima airport was used as a case study, for which two alternatives are proposed, each one with a different type of energy dissipator, but both designed to have similar performance. Finally, the reductions obtained by both the simplified models and three-dimensional models are compared. It is concluded that the simplified models allow a fast and acceptable prediction of the levels of reduction of the seismic response in buildings that incorporate energy dissipators.

The COVID-19 pandemic wreaked havoc worldwide, with profound economic, environmental, and social implications. The demand for land freight transport indicates the economic situation of a developing country such as Ecuador. The main objective of this work is to evaluate the economic impact caused by   the COVID-19 pandemic on land freight transport (TTC, acronyms in Spanish). For this purpose, a sample of 212 companies in the province of Pichincha was used, segmented by size, i.e., large (10), medium (63), small (49) and micro-companies (90), analyzing information regarding sales revenue, total sales, and profits for that period.  The results showed that large and small companies in the province were the most affected, with total losses of US$8 million and US$ 600,000, respectively. In contrast, the medium-sized companies were the only segment that achieved positive profits of around US$ 3 million. In addition, a general analysis was made of the contribution of the TTC in these productive sectors. In the future, this analysis may help planners and decision-makers implement public policies to improve the sector's performance and react to future economic downturns. Events such as the COVID-19 pandemic demonstrate that the TTCD must be quick and flexible; acting in the short term is crucial to encourage recovery. Finally, a proper revival of the sector requires cooperation between the various public and private economic players.

In Latin America, a large part of agricultural production is carried out by small producers with low levels of modernization and lacking robust logistic processes, which limits the possibility of accessing large markets with competitive prices, affecting their economic growth and welfare possibilities. This research develops a model for the optimal location of facilities (agricultural warehouses) for agricultural producers, where product consolidation is achieved. The purpose is to reduce logistics and transportation costs by jointly exploiting economies of scale, considering the variability of some factors, and analyzing scenarios. Synergies between producers would increase access to large markets, facilitate consolidation processes and add value. A mixed-integer linear programming model was formulated, consisting of a network of shared multi-product, multi-customer, multi-period collection centers, with the option of direct trips or through the consolidating centers. The system is supported by a prototype web platform that will allow farmers greater participation and commercial negotiating power. The model was applied to small producers in the department of Atlántico, Colombia, and the results verified the benefits of the proposal. This study proved that agricultural warehouses generate potential economic benefits for the system. The main factors influencing the results are production levels, distance transported, and product quality.

SEDAPAL is a Peruvian state company under private law. It is the first service provider company for drinking water supply, sewerage, and waste treatment, whose production represents 40% of the country's GDP. As of December 2020, its capital stock amounted to S/ 5,381.3 million and generated an income of S/ 1,930 million. It has total assets of S/ 12,418 million, of which 43% are financed by equity and 57% by liabilities or debt. At the end of 2020, the company presents unfavorable management results and 82.5% progress in the strategic plan. By implementing the improvement proposal, it will be possible to enhance tools that support project management, increase efficiency in project management, and develop the team. The improvement proposal allows for mitigating the risks to users, suppliers, and the COVID-19 crisis. First, the information is reviewed, the supply chain is investigated, and it is diagnosed with value stream mapping and rethinking the supply chain., Finally, the improvement proposals are evaluated with supply chain operations reference, analytic network process, and super decision methodologies. The budget to implement the investment project is S/ 1,617,000. After the proposed analysis, a positive NPV and IRR were obtained, which support the project’s feasibility.

In emergency scenarios, it is usually difficult to rely on network infrastructure, especially in remote or geographically difficult-to-access locations. However, it is necessary to have tools to communicate or assess the situation. Therefore, ad hoc networks emerge as an option to solve this problem. This paper proposes the development of an emergency communication system for the transmission of multimedia traffic in a real scenario, between the different floors of a building. For this purpose, multiple experiments were carried out to determine the values of fundamental metrics (e.g., packet loss, delay, and throughput) for real-time audio and video transmission. Specifically, open-source tools were developed with the ability to extract the required metrics and objectively compare video quality using current encoding mechanisms (e.g., VP8, VP9, H.264, H.265). The results obtained show that VP8 is the most suitable codec for the proposed scenario. In addition, a videoconferencing tool was developed with the ability to adapt the video characteristics (e.g., bitrate) according to the network conditions.

In agriculture, water is vital for the crop. Knowing when to irrigate and how much to irrigate can be answered technically from data provided by weather stations. However, this data is not always available. In addition, although irrigation controllers are available on the market, they are not integrated with the stations and have a closed architecture. On the other hand, the development of electronics, the availability of affordable sensors, protocols, standards and open source, facilitate the integration of hardware and software components. This work proposes a prototype of an intelligent weather station that provides real-time data on temperature, ambient humidity, soil moisture, and rainfall, as input for a controller to activate irrigation in two cases: i) due to the need of water for crop development; or ii) to mitigate frost, supporting sustainable agricultural development with local, open source and affordable technology. The methodology was applied based on rapid prototyping, evaluating the operability of each electronic device and its integration in a controlled environment, and then in an experimental plot, at the Nero farm of the University of Cuenca. Open-source hardware and software were used for the development, using Arduino IDE and Visual Studio Code. A solar panel and batteries were used to power the system, optimizing consumption. This prototype has shown continuous and stable operation at 3100 meters over the sea level. It will continue to be monitored and improved, in order to make it available to the end user in the future.

Industrialization and the rapid growth of urban areas are alarmingly increasing the presence of air pollutants. These pollutants affect the quality of life of people and present an opportunity for study is created to determine the atmospheric behavior and relationship between meteorological variables present in the environment. Prior to this, rolling windows of time were applied to remove anomalous data. Next, variables were identified, and the data was segmented through the X-means algorithm. Also, two clusters that represent the relationships between pairs of variables and the temporality of the time windows. As a result, an inverse correlation of -0.78 was found between the ozone and dew point variables within the hours of the working day.

This article performs a comparative analysis of the power intensity levels measured with the Network Cell Info Lite application and the performance of the different propagation models: Log-Normal, Okumura Hata, COST 231, Walfish Bertoni, and SUI in the 4G LTE Frequency Band. The study was conducted in five LTE coverage cells located in the southern area of the city of Riobamba. The model that best fits each cell was chosen by means of absolute error analysis, thus obtaining an empirical correction factor for the proposed models. For the analysis of the absolute error, three measurement campaigns were carried out with 50 samples where the mean value was obtained. After applying the aforementioned models, the Log-Normal model yielded the most favorable results, being the one that achieved the best adaptation in Riobamba, since the power levels vary in the range (-80; -106) dBm at a coverage area not exceeding 200m.