Evaluación del Proceso Consultivo Ciudadano en Villa el Salvador, Lima, Peru

El presente informe contiene un estudio de caso sobre “Evaluación del Proceso Consultivo Ciudadano en Villa el Salvador, Lima, Perú” realizado para el Instituto de Estudios de Vivienda y Desarrollo Urbano - IHS (Institute for Housing and Urban Development Studies) y el Programa SINPA (Support for the Implementation of National Plans of Action - Habitat II), que realiza estudios en varios países de América Latina sobre procesos de gestión urbana con el objetivo de apoyar a los gobiernos locales al mejoramiento de su gestión urbana. Una misión fue ejecutada por Rein Skinner supervisor del IHS y el trabajo fue realizado por Julio Calderón Cockburn, Consultor, como investigador local, y por la Arq. Liliana Marulanda como investigadora del IHS. Como lineamientos guía para el desarrollo de la investigación, el equipo local ha seguido los lineamientos del documento “Diseño de Investigación para los Procesos Consultivos" proporcionado por el IHS. El informe final se orienta en términos de contenidos, estructura y presentación por el documento “Review of the Lusaka City Consultation Process”, aunque se han efectuado algunas modificaciones atendiendo a la peculiaridad del caso de Villa El Salvador (VES). Las preguntas de investigación han sido las siguientes: ¿Cuáles son los resultados e impactos del proceso consultivo sobre la gobernanza urbana, la reducción de la pobreza y el medio ambiente urbano?; ¿ Qué lecciones pueden ser aprendidas de esas experiencias? Y ¿Cómo puede efectuarse un seguimiento de las acciones a ser recomendadas

Necesidades hídricas de dos variedades de fríjol (phaseolus vulgaris l.) en condiciones de invernadero

Se analizó el efecto de diferentes láminas de agua, determinados con base en la evaporación del tanque evaporímetro tipo A, colocado fuera del invernadero. Se presentaron diferencias significativas entre los tratamientos húmedos y secos, incrementándose el desarrollo vegetativo a medida que aumentaban las cantidades de agua presente en el suelo. Las mayores producciones de fríjol en las variedades Porrillo y Calima se obtuvieron con láminas de 229 mm y 199 mm respectivamente.The effect of different water sheets, determined by the evaporation in a type A evaporimeter tank, on the yield of bean (Phaseolus vulgaris) was analyzed. Significant differences were found between the humid and dry treatments with an increasing plant development as the amount of water in the soils rised. The highest bean yields in the Porrillo and Calima varieties were obtained with water sheets of 229 mm and 199 mm respectively

A comparative study of hysteresis band PWM techniques for current control in shunt active power filters

El presente artículo evalúa el desempeño de un filtro activo empleando tres diferentes técnicas de control de corriente de banda de histéresis: banda fija, banda adaptativa y con modulación por vector espacial. En la comparación se estudian las características de cada técnica y mediante simulación se evalúa su desempeño y operación. En todos los casos se emplea la teoría pq para el cálculo de las corrientes de referencia y se emplea un controlador proporcional para regular la tensión del bus de continua. De acuerdo con los resultados, las técnicas PWM evaluadas permiten una reducción del contenido armónico de la corriente de la red de alimentación de 31 % sin compensación, a un 6 %, considerando el filtro activo de potencia. La técnica de banda adaptativa de histéresis presenta el más bajo desempeño en la reducción de armónicos en las corrientes de la red. Además, se tiene que el método de banda fija de histéresis es el más recomendado para aplicaciones de filtros paralelo debido a que posee una estructura más simple que permite su implementación. Los resultados tambien muestran que la técnica de banda adaptativa de histéresis es la que presenta mayor reducción en las variaciones de la frecuencia de conmutación, requiriendo mayor número de operaciones, ya que requiere calcular el ancho de banda en cada iteración. Mientras que la técnica de modulación por vector espacial y banda de histéresis presenta frecuencias de conmutación altamente variables y mayor complejidad en su implementación.This paper evaluates the performance of an active power filter using three hysteresis band current control techniques: fixed-band, adaptive-band, and Space Vector Modulation. The characteristics of each method, along with their behaviour under different operating conditions, are studied by means of time domain simulations. The pq theory is used in all the cases to calculate the current reference, and a proportional controller is implemented to regulate the voltage in the dc bus. Based on the results, the PWM techniques evaluated in this work enable a reduction in the harmonic content of the supply grid currents that ranges from 31% without compensation to 6% after the active power filter is connected. The adaptive hysteresis band method exhibited the worst performance in the elimination of harmonics in grid currents; furthermore, it presented the largest reduction of variations in the switching frequency and requires more calculation time because the band width must be computed at each iteration. In turn, the fixed hysteresis band alternative is the most widely recommended for applications that involve parallel filters because it has a simpler structure that enables its implementation. Finally, the technique that combines space vector modulation and hysteresis band current control produced highly-variable switching frequencies and a more complex implementation

A Snapshot of the International Views of the Treatment of Rectal Cancer Patients, a Multi-regional Survey: International Tendencies in Rectal Cancer

BACKGROUND: Management of rectal cancer has a number of potentially appropriate alternatives for each patient. Despite acceptance of standards, practices may vary among regions. There is significant paucity of data in this area. The objective was to create a snapshot of the regional differences. DESIGN: This online survey included 10 questions. Enquiries focused on controversial topics, on surgeon and hospital volume, surgical margins, appropriateness of surgical approaches and techniques, watch-and-wait strategies, and total neoadjuvant therapy. Major colorectal surgery societies around the world were asked to invite their members to complete the survey. OUTCOME MEASURES: Frequency of responses across regions within each question was compared by Fisher's exact test. RESULTS: Seven hundred and fifty-three participants from 60 countries responded. Eight regions were identified, and four had sufficient representation for comparisons. Similarities and differences in the therapies among these regions were identified. Robotic surgery penetrance is higher in North America, and watch and wait is more accepted in South America. Patients in Oceania are more likely to be diverted; Europe has more usage of taTME. DISCUSSION: This online survey was practical as a mean to provide a rapid assessment of the international picture on consistency and variability of rectal cancer patients' care, and to potentially identify opportunities to standardized care to patients. Medical surveys have inherent limitations; pertinence to our study is selection bias. CONCLUSIONS: The management of rectal cancer varies among different regions. Identification of differences is important when considering global efforts to improve management and interpret data

Hardware-in-the-loop to test an mppt technique of solar photovoltaic system: A support vector machine approach

Indexación ScopusThis paper proposes a new method for maximum power point tracking (MPPT) of the photovoltaic (PV) system while using a DC-DC boost converter. The conventional perturb and observe (P&O) method has a fast tracking response, but it presents oscillation around the maximum power point (MPP) in steady state. Therefore, to satisfy transient and steady-state responses, this paper presents a MPPT method using support vector machines (SVMs). The use of SVM will help to improve the tracking speed of maximum power point of the PV system without oscillations near MPP. A boost converter is used to implement the MPPT method, where the input voltage of the DC-DC converter is regulated using a double loop where the inner loop is a current control that is based on passivity. The MPPT structure is validated by hardware in the loop, a real time and high-speed simulator (PLECS RT Box 1), and a digital signal controller (DSC) are used to model the PV system and implement the control strategies, respectively. The proposed strategy presents low complexity and it is implemented in a commercial low-cost DSC (TI 28069M). The performance of the MPPT proposed is presented under challenging experimental profiles with solar irradiance and temperature variations across the panel. In addition, the performance of the proposed method is compared with the P&O method, which is traditionally most often used in MPPT under demanding tests, in order to demonstrate the superiority of the strategy presented. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.https://www.mdpi.com/2071-1050/13/6/300

Comparing ‘Twitter’ polls results with an online survey on surgeons perspectives for the treatment of rectal cancer

INTRODUCTION: Traditional surveys (including phone, mail and online) can be valuable tools to obtain information from specific communities. Social media apps such as Twitter are being increasingly adopted for knowledge dissemination and research purposes. Twitter polls are a unique feature which allows for a rapid response to questions posed. Nonetheless Twitter does not constitute a validated survey technique. The objective was to compare the similarities of Twitter polls in describing practice patterns for the treatment of rectal cancer. METHODS: A survey on the management of rectal cancer was designed using modified Delphi methodology. Surgeons were contacted through major colorectal societies to participate in an online survey. The same set of questions were periodically posted by influencers on Twitter polls and the results were compared. RESULTS: A total of 753 surgeons participated in the online survey. Individual participation in Twitter ranged from 162 to 463 responses. There was good and moderate agreement between the two methods for the most popular choice (9/10) and the least popular choice (5/10), respectively. DISCUSSION: It is possible that in the future polls available via social media can provide a low-cost alternative and an efficient, yet pragmatic method to describe clinical practice patterns. This is the first study comparing Twitter polls with a traditional survey method in medical research. CONCLUSIONS: There is viable opportunity to enhance the performance of research through social media, however, significant refinement is required. These results can potentially be transferable to other areas of medicine

Parameter estimation for an electric arc furnace model using maximum likelihood

Este documento presenta una metodología para determinar los parámetros de un modelo de un horno de arco eléctrico usando máxima verosimilitud (máximum likelihood estimation - MLE). La estimación por máxima verosimilitud es uno de los métodos de estimación de parámetros clásica más empleada en la práctica. El modelo de horno de arco utilizado considera las variaciones aperiódicas y la no linealidad en su característica voltaje-corriente. Se ha utilizado el toolbox NETLAB desarrollado para MATLAB®, para solucionar el sistema de ecuaciones no lineales que relacionan los parámetros del modelo que se requieren estimar. Los resultados obtenidos en simulación del modelo del horno de arco implementado en PSCADTM, se comparan con mediciones reales tomadas en la etapa más crítica de la operación del horno. Se muestra como el modelo del horno de arco captura con gran detalle las formas de onda de voltajes y corrientes reales de los arcos eléctricos generados al interior del horno. Los resultados obtenidos muestran un error máximo de 5,03 % en las corrientes eficaces del arco eléctrico y 11,4 % en los voltajes eficaces de fase del secundario del transformador que energiza los electrodos del horno.In this paper, we present a methodology for estimating the parameters of a model for an electrical arc furnace, by using maximum likelihood estimation. Maximum likelihood estimation is one of the most employed methods for parameter estimation in practical settings. The model for the electrical arc furnace that we consider, takes into account the non-periodic and non-linear variations in the voltage-current characteristic. We use NETLAB, an open source MATLAB® toolbox, for solving a set of non-linear algebraic equations that relate all the parameters to be estimated. Results obtained through simulation of the model in PSCADTM, are contrasted against real measurements taken during the furnance's most critical operating point. We show how the model for the electrical arc furnace, with appropriate parameter tuning, captures with great detail the real voltage and current waveforms generated by the system. Results obtained show a maximum error of 5% for the current's root mean square error

Technical and clinical evaluation of a closed loop TIVA system with SEDLineTM spectral density monitoring: Multicentric prospective cohort study

Introduction: Closed loop total intravenous anesthesia is a technique in which the patient’s hemodynamic and anesthetic depth variables are monitored, and based on this information, a computer controls the infusion rate of drugs to keep them within pre-established clinical parameters. Objective: To describe the technical and clinical performance of a closed loop system for total intravenous anesthesia with propofol and remifentanil, using the SEDLineTM monitor Design: Multicentric prospective cohort study Setting: Surgery room Patients: ASA I-II undergoing elective surgery Measurements: The authors designed a closed loop system that implements a control algorithm based on anesthetic depth monitoring and the Patient State Index (PSITM) of the SEDLine monitor for propofol, and on hemodynamic variables for remifentanil. The measurement of clinical performance was made based on the percentage of PSITM maintenance time in the range 20–50. Precision analysis was evaluated by measuring median performance error (MDPE) can be defined as the median difference between actual and desired values, which refers to the degree of precision in which the controller is able to maintain the control variable within the objective set by the anesthesiologist; it represents the direction (over-prediction or underprediction) of performance error (PE) rather than size of errors, which is represented by MDAPE, median absolute percentage error, Wobble index, which is used for measuring the intrasubject variability in performance error. Results: Data were obtained from 93 patients in three healthcare centers. The percentage of PSITM maintenance time in the 20–50 range was 92% (80.7–97.0). MDPE was 10.7 (− 11.0–18.0), MDAPE 21.0 (14.2– 26.8) and wobble 10.7 (7.0–16.9). No adverse surgical or anesthetic events were found

Toward zero-deforestation value chains: Environmental upgrading and downgrading among non-certified cocoa producers in Colombia

Global pressure to make value chains less damaging to the natural environment, a process known as environment upgrading, has been building in recent years. Most studies that assess environmental upgrading have focused on the compliance of suppliers, which would be farmers in the case of value chains involving agrifood commodities, to sustainability certification standards. Our case study focusing on cocoa producers in Colombia explores an under-investigated topic in environmental upgrading — that of whether sustainable practices of non-certified farmers facilitate zero-deforestation value chains. Using data from 930 randomly sampled households in the Colombian departments of Caqueta and Cesar, we examined the association of non-certified sustainable practices, i.e., processes that benefit the environment which farmers undertake on their own and not because of adherence to sustainability certification criteria, with reforestation and deforestation: A positive association of the practices with the former suggests environmental upgrading, while with the latter would be environmental downgrading, which denotes negative environmental outcomes from the process of environmental upgrading. We also assessed whether or not there are significant differences between mean deforestation and reforestation rates between certified and non-certified cocoa producers in both departments. Based on statistical tests, we found that (a) non-certified sustainable practices can facilitate environmental upgrading and discourage environmental downgrading but only in some cases, and (b) there is no significant difference in mean deforestation rates between certified and non-certified surveyed cocoa producers, but there is a significant difference in mean reforestation rates between the two groups of producers. These results suggest that implementing non-certified sustainable practices poses another way to enable value chain actors to meet the requirements in markets seeking sustainably produced commodities. One such market is that of the European Union, whose legislation on deforestation-free commodities makes certification an optional rather than compulsory process to support the prescribed procedure on diligence procedure