Accepted Papers

IDC Sensor for Low-Cost Water Quality Monitoring Applications

 

Received: May 13, 2020 | Accepted: March 17, 2021

 

Abstract: In order to properly monitor the health status of the hydrological resources of a region, in terms of water contamination, a scalable and low-cost system is necessary in order to map the water quality at different locations and allow the prioritization of more sophisticated and expensive monitoring campaigns on those areas where a suspicious behavior seems to be occurring. This paper presents the design and implementation process of such an IoT-based solution for low-cost and scalable water quality monitoring applications. To that end, we propose the utilization of a low-cost inter-digital capacitance (IDC) sensor to characterize the conductivity of the water, a very telling parameter about the level of pollution in the water. Additionally, an embedded method to measure such sensor was designed and implemented, which considers the requirements of a portable platform: low computational capabilities, small memory and low power consumption. Our results show that an IDC sensor is capable of detecting the changes of the capacitance of the sample, and therefore mapping the changes in the conductivity of the water. Additionally, integrating an embedded measuring method is a valid option for in-situ characterization of water samples and the complete solution enables a new paradigm for water quality monitoring in large scale scenarios.

 

Keywords: Inter-digital capacitance; low-cost; water quality; pollutants; FFT; charging time; IoT.

 


 

Technologies in Wastewater Treatment Plants for the Removal of Antibiotics, Resistant Bacteria and Antibiotic Resistance Genes: a Review of the Current Literature

 

Received: February 18, 2020 | Accepted: March 17, 2021

 

Abstract: This study aimed to evaluate the efficiency of technologies for removing antibiotics, antibiotic-resistant bacteria and their antibiotic resistance genes, and the countries where they have been developed. For this purpose, was conducted a systematic review to identify the tertiary treatments to remove the above-mentioned pollutants. The ScienceDirect and Scopus databases were used as sources of information, taking into account only experimental research from 2006 to 2019 and technologies with removal rates higher than 70% to the information analyses. From the analysis of 9 technologies evaluated, in a set of 47 investigations, photo-Fenton, and electrochemical treatments were found to be the most efficient in the removal of antibiotics; gamma radiation and photocatalysis with TiO2 and UV revealed better results in the removal of resistant microbial agents and their resistance genes, with efficiencies of 99.9%. As one of the largest producers and consumers of antibiotics, China appears to be the country with the most scientific research on the area. The importance of innovation in wastewater treatment processes to achieve better results in the remotion of antibiotics, antibiotic-resistant bacteria, and their resistance genes is highlighted, given the effects on the aquatic ecosystems and public health.

 

Keywords: Antibiotics, sewage treatment, antibiotic resistance bacteria, antibiotic resistance genes.

 


 

Operating Room Time Prediction: An Application of Latent Class Analysis and Machine Learning

 

Received: November 8, 2019 | Accepted: March 17, 2021

 

Abstract: Objective: The goal of this research was to evaluate the influence of the incorporation of Sugarcane Filter Cake (SFC) as an amendment material (AM) on the process of biowaste (BW) composting and the quality of the final product. Methods: In this study the effect (in terms of stability, maturity and agricultural value) of SFC incorporation on four mixture proportions BW:SFC (100:00–control; 90:10; 80:20 and 70:30) was evaluated on a pilot scale. Results: The results show that overall, the incorporation of SFC enabled thermophilic temperatures to be achieved in a shorter time than the control treatment and improved the stability conditions (oxygen consumption <1.0 mgO2/gVSh), germination index (GI >80%: mature product) and quality product index (FI >3.5: high soil fertilization potential). The mixing ratio 80:20, showed the best product quality (highest total N content: 2.32%, TP: 1.42%, CEC: 65.5 meq/100 g), lower electrical conductivity (EC) value (0.38 dS/m) and total and fecal coliforms (15.3 and 4.0 NMP/g respectively), complying with technical standards (Colombian and Chilean) for organic products used as fertilizers and amendments or soil conditioners. In addition to demonstrating the best results of GI and FI (123.40% and 4.67 respectively).

 

Keywords: Agricultural value, Amendment material, Biowaste, Co-composting, Filter cake.

 


 

Improvement of Biowaste Composting by Addition of Sugarcane Filter Cake as an Amendment Material

 

Received: March 18, 2020 | Accepted: January 29, 2021

 

Abstract: Objective: The goal of this research was to evaluate the influence of the incorporation of Sugarcane Filter Cake (SFC) as an amendment material (AM) on the process of biowaste (BW) composting and the quality of the final product. Methods: In this study the effect (in terms of stability, maturity and agricultural value) of SFC incorporation on four mixture proportions BW:SFC (100:00–control; 90:10; 80:20 and 70:30) was evaluated on a pilot scale. Results: The results show that overall, the incorporation of SFC enabled thermophilic temperatures to be achieved in a shorter time than the control treatment and improved the stability conditions (oxygen consumption <1.0 mgO2/gVSh), germination index (GI >80%: mature product) and quality product index (FI >3.5: high soil fertilization potential). The mixing ratio 80:20, showed the best product quality (highest total N content: 2.32%, TP: 1.42%, CEC: 65.5 meq/100 g), lower electrical conductivity (EC) value (0.38 dS/m) and total and fecal coliforms (15.3 and 4.0 NMP/g respectively), complying with technical standards (Colombian and Chilean) for organic products used as fertilizers and amendments or soil conditioners. In addition to demonstrating the best results of GI and FI (123.40% and 4.67 respectively).

 

Keywords: Agricultural value, Amendment material, Biowaste, Co-composting, Filter cake.

 


 

Optimization of machining parameters for product quality and productivity in turning process of aluminum

 

Received: November 8, 2019 | Accepted: January 29, 2021

 

Abstract: Modern production process is accompanied with new challenges in reducing the environmental impacts related to machining processes. The turning process is a manufacturing process widely used with numerous applications for creating engineering components. Accordingly, many studies have been conducted in order to optimize the machining parameters and facilitate the decision-making process. The objective of the present work is to optimize the quality of the machined products (surface finish) and the productivity rate of the turning manufacturing process. To do this, we use Aluminum as the material test to perform the turning process with cutting speed, feed rate, depth of cut, and nose radius of the cutting tool as our design factors. Product quality is quantified using surface roughness (R_a) and the productivity rate suing material removal rate (MRR). We develop a predictive and optimization model by coupling artificial neural networks (ANN) and the Particle Swarm Optimization (PSO) multi-function optimization technique, as an alternative to predict the model response (R_a) first and then search for the optimal value of turning parameters to minimize the surface roughness (R_a) and maximize the material removal rate (MRR). The results obtained by the proposed models indicate good agreement between the predicted and experimental values proving that the proposed ANN model is capable of predicting the surface roughness accurately. The optimization model PSO has provided a Pareto Front for the optimal solution determining the best machining parameters for minimum R_a and maximum MRR. The results of this study offers application in the real industry where the selection of optimal machining parameters helps to manage two conflicting objectives, which eventually facilitate the decision-making process of machined products

 

Keywords: Multi-Objective Optimization, Artificial Neural Networks, Turning process, Surface Roughness.

 


 

Uncertainty estimation in the sphygmomanometers calibration according to OIML R16-1 from a legal metrology perspective

 

Received: June 29, 2019 | Accepted: October 22, 2020

 

Abstract: Objective: To estimate the uncertainty in the calibration of sphygmomanometers according to OIML R16-1 from a legal metrology perspective. Materials and methods: Four (4) sphygmomanometers of different brands with a resolution of 2 mmHg were selected to perform the calibration, using several direct comparisons between a sphygmomanometer and a digital standard manometer with a resolution of 0,01 mmHg, generating pressure with a pneumatic clamp. The uncertainty was estimated using the Guide to the Expression of Uncertainty of Measurement (GUM) and the OIML R16-1 international recommendation, where two measurement series were computed, each one with upward and descendent sequence, for achieving 4 measurements each time with the corresponding errors. Results and discussion: Several uncertainty representations were achieved, in particular expressions, such as, type A, type B and expanded, by means of a physic modelling and a non-stochastic mathematic model. From the sphygmomanometer measurement series in calibration processes, the uncertainty contributions were analyzed, finding that the dominant uncertainty source, in most cases, is derived from the equipment resolution, followed by repeatability and hysteresis in the sphygmomanometer test processes. Conclusions: The proposed structure for estimating uncertainty follows international regulations and can be used in procedures for approval of models with a final impact on patient safety.

 

Keywords: legal metrology, sphygmomanometers, uncertainty.  

 


 

Biofilms production from avocado waste

 

Received: March 18, 2019 | Accepted: October 13, 2020

 

Abstract: Objective: To obtain biofilms from starch and cellulose present in the avocado (Persea americana) peel and seed. Materials and methods: The starch characterization included humidity, gelatinization temperature, paste clarity, absorption index, solubility index, swelling power, amylose, amylopectin, amount, and starch yield. Five mixtures were made with 3 g of starch, 5 mL of 30% NaOH (w/v), 3 g of cellulose, and different proportions for glycerin: 2 g, 2.5 g, 3 g, 3.5 g, 4 g, and PVA: 2 g, 3 g, 4 g, 5 g, and 6 g. Films were formed on acrylic plates, using the casting method. The bioplastic was characterized in terms of moisture, solubility in water, density, thickness, biodegradability, stress, deformation, and modulus of elasticity. Results and discusión: The addition of cellulose to the mixture does not contribute to film formation, unlike PVA which did. The film had the best physical appearance with a mixture of 2 g of glycerin and 6 g of PVA. The bioplastic characterization was 23.43% humidity, 39.39% for water solubility, 1.52 g/cm3 density, 0.58 mm thickness, 21.03% weight loss for the biodegradability test, 1.53 MPa for tension, 21.25 % deformation, and 10.04 MPa for the modulus of elasticity. Conclusions: The bioplastic obtained did not show the resistance of traditional plastic. However, the results obtained serve as a starting point for the realization of other formulations, aimed at producing a bioplastic capable of competing with its synthetic relatives.

 

Keywords: biopolymers, bioplastic, biodegradable, food waste.

 


 

Finding Installed Capacity For Practical Training In A Service At A University Hospital

 

Received: February 28, 2019 | Accepted: October 13, 2020

 

Abstract: Objetivo: Proponer una metodología para determinar el número de estudiantes que rotan en una práctica médica en un hospital universitario, de modo que se garantice la calidad en los procesos de capacitación y en la atención a los pacientes. Materiales y métodos: Se propone un procedimiento que consta de tres pasos, para encontrar el número de estudiantes que la institución puede aceptar simultáneamente, el método se basa en un modelo de programación lineal entera. Resultados: El método propuesto se implementó, para evaluar la capacidad instalada del servicio de Cirugía General en el Hospital Universitario Clínica San Rafael, aumentando en dos estudiantes (33%) la capacidad que ofrecía el hospital al aceptar estudiantes. Conclusiones: La metodología propuesta además de garantizar la calidad en los procesos de capacitación y en la atención a los pacientes genera otros resultados intangibles, como poder contar con una forma más ágil de planeación, lo que reduce el tiempo de planificación. La metodología es fácilmente extensible a otros servicios dentro de los hospitales.

 

Keywords: Installed capacity, staffing problem, scheduling problema

 


 

Real-time Coordinated Scheduling for Cloud Radio Access Networks in a Software-only Environment using the OpenAirInterface platform

 

Received: September 22, 2019 | Accepted: August 14, 2020

 

Abstract: The objective of this paper is to extend into the OpenAirInterface platform the Coordinated Scheduling (CS) technique to allocate resource blocks among User Equipment (UE) in a wisely way and to control the energy efficiency, the throughput, and the inter-cell interference for Cloud Radio Access Networks (C-RANs). It is achieved by modifying the OpenAirInterface scheduler code, increasing the Remote Radio Unit (RRU) scalability, and employing some component carriers of the Radio Cloud Center (RCC), each one them with one or more UEs. The hardware utilized is composed of general-purpose processors and fast Ethernet transport ports, and the software is recent frequency-domain methodologies in a software-only environment where the use of radio units are not required. However, the USRP B200 mini-i radio unit and the UE (Samsung Galaxy S8) were considered only for validation purposes. The emulations using frequency-domain methodologies, compatible with fourth and fifth-generation cellular systems, allowed real-time emulations and reduced 10-fold the multipath channel’s signal processing complexity compared to time-domain methodologies. The results show we can emulate a real-time static coordinated scheduling proof-of-concept for one C-RAN composed of one RCC, three RRUs, and three UEs. In the end, it is evaluated the reproducibility and the scalability of synthetic networks composed of one RRU and at least one UE, without using software-defined radio units, reducing prototyping uncertainties of the physical hardware and the total price of the experiment.

 

Keywords: C-RAN, synthetic network, coordinated scheduling, frequency-domain methodologies, time-domain methodologies, software-only environment, OpenAirInterface.

 


 

Four-quadrant Characterization of Hydrodynamic Phenomena in a Low Specific Speed Centrifugal Pump

 

Received: March 4, 2020 | Accepted: July 29, 2020

 

Abstract: Objective: identify and characterize subsynchronous hydrodynamics phenomena in a low specific speed centrifugal pump based on its four-quadrant characteristic curve. Materials: a 1.5 HP ITT Goulds pump instrumented with pressure transductors, an accelerometer, a torque sensor and a tachometer. Flow rate measurement was done with an ultrasonic transit time clamp-on flow meter. Methods: time and frequency domain analysis with phase analysis were used to identify spectral components linked to hydrodynamic phenomena such as rotating stall and surge. Results and discussion: this work approaches an alternative method to calculate the phase angle using pressure signals without filtering. Related with hydrodynamic phenomena, the evidence collected suggests the presence of rotating stall in some operation points of the four-quadrant characteristic curve. Furthermore, in the third quadrant, rotating stall coexist with surge. Conclusions: The instrumentation and methods regarded in this work allow to collect evidence to identify in-phase and out of phase subsynchronous hydrodynamic phenomena. The classic cross-correlation-based method was improved to ease the diagnosis of subsynchronous phenomena by visual inspection. A new quantitative approach was introduced to detect subsynchronous phenomena, based on the Fourier analysis; it was validated with a case study for which the classical method was not suitable.

 

Keywords: subsynchronous phenomena, rotating stall, surge, spectral analysis, phase análisis.

 


 

Study of concentration-depth profiles of the titanium and nitrogen ions by SRIM/TRIM simulation

 

Received: December 12, 2019. | Accepted: July 29, 2020

 

Abstract: In this research, the concentration-depth profiles reached by titanium and nitrogen particles, on the surface of AISI/SAE 1020 carbon steel substrates, by using of ion implantation technique, are studied. The ions are surface deposited by means of high voltage pulsed discharges and electric arc discharge under high vacuum conditions. The concentration and position distribution of the metallic and non-metallic species are obtained by simulation of the interaction of ions with the matter, stopping and ranges of ions in the matter, by the computer program transport of ions in matter. The implantation dose is calculated from the discharge data and the previously established study parameters in this work. From the simulation results, the depth profiles demonstrated that titanium and nitrogen ions may reach up to 300 Angstroms and 600 Angstroms and concentrations of 1.478x10^16 ions⁄cm^2 and 2.127x10^16 ions⁄cm^2 respectively. The formation of titanium microdroplets upon the surface of the substrates is identified from the micrographs obtained by the scanning electron microscopy technique; furthermore, the presence of titanium and nitrogen implanted on the surface of the substrate is verified through the elemental composition analysis by the energy dispersive spectroscopy, validating the effect of ion implantation on ferrous alloys.

 

Keywords: Carbon steel; dose; electric arc; surface modification; ion implantation; transport of ions in matter.

 


 

Prototype for knee-load relief through ischiatic support

 

Received: June 30, 2019 | Accepted: July 29, 2020

 

Abstract: Objective: the objective of this work was to develop a passive exoskeleton prototype for the relief of knee-load employing ischiatic body weight support. Methods and materials: a functional prototype was developed and tested with three volunteers to analyze its potential effectiveness and effects on gait kinematics. The performance of the prototype was assessed using motion capture and pressure mapping systems, and a testing bench for the study of ischiatic body weight. Results and discussion: the results of the tests indicate that the prototype allows reducing the load supported by the knees and does not have a significant effect on the kinematics of the hip and knee joints. The process allowed the designers to identify possibilities of improvement mainly on reducing the restrictions imposed by the prototype to the motion of the ankles, especially on the midstance of the support phase. Conclusions: the passive exoskeleton prototype developed for ischiatic body weight support allows setting different percentages of knee-load relief. The prototype does not have a significant effect on the kinematics of the hip and knee joints. Nevertheless, improvements must be performed to reduce the restrictions to the motion of the ankles.

 

Keywords: arthrosis, knee-load relief, exoskeleton.

 


 

Design of a CPFR, location, inventory and routing approach to diabetes and high blood pressure medicines supply network planning

 

Received: June 29, 2019. | Accepted: April 1, 2020

 

Abstract: Objectives: The purpose of this work was to compare nutrient concentrations in water, sediment, and in plant tissues of Eichhornia crassipes and Panicum elephantipes from lotic and lentic environments of the Middle Parana River floodplain (Argentina). Materials and Methods: The study was carried out over an 18-month period. Plants, water, and sediment were collected in a lake (lentic environment) and in a river (lotic environment) from the Middle Parana River floodplain. Water and sediment were sampled in sites where P. elephantipes or E. crassipes were predominant and in sites without vegetation. Results and Discussion: The lentic and lotic environments dominated by E. crassipes showed the highest ammonium concentrations. The sediment from the lotic environment showed total phosphorus (TP) and total Kjeldahl nitrogen (TKN) concentrations significantly lower than those found in the sediment from the lentic environment. In the lentic environment, the sediment from the lake with the dominance of E. crassipes showed the highest TKN concentration, while the sediment from the lake dominated by P. elephantipes showed the highest TP concentration. For both plant species and for both environments, TKN and TP tissue concentrations were significantly higher in leaves in comparison with roots. Conclusions: Our results could be used to optimize the efficiency of treatment wetlands. Additionally, the use of locally available macrophytes as contaminant bioaccumulators in the Middle Parana River floodplain is completely feasible.

 

Keywords: CPFR, Medicines Supply Chain, Optimization