Abstract Paper aims This study presents several business analytics tools that allow improving the tactical planning of the collection process for a Colombian solid-waste management company. Originality The extant literature of operations research/analytics applied to these systems focuses on facility location or vehicle routing. Tactical decisions are seldom studied in the operations research/analytics literature devoted to waste management systems. By contrast, the focus of this paper is on tactical decisions: fleet sizing, frequency assignment, route scheduling and internal resource allocation in a new waste transfer station. Research method We follow a multimethodology approach that uses mathematical programming, metaheuristics, and discrete event simulation. The models use historical information of the system, and the solution of a model are used as input data for the other models. Main findings Introducing a new waste transfer station allows an important reduction of the compactors fleet. However, to prevent a collapse in its internal operation an even operation is needed. This is achieved by rescheduling the routes to balance their arrival during the day. Additional benefits can be attained if some soft constraints are relaxed. Implications for theory and practice Practitioners looking for tactical planning tools on waste collection systems have here an example of their application and benefits. Improvements can be achieved by tactical planning without heavily disrupting decisions at the operational level.

ABSTRACT This study aimed to evaluate the lactation curve of female Murrah buffaloes, using mixed nonlinear models (NLM), across three lactation periods (180 d, 210 d, and 240 d). A total of 5334 data on daily milk production (kg) were analyzed. The data were collected every seven days in the interval of one to 250 days of lactation, corresponding to 221 lactations and 145 females, with calvings from 2017 to 2019. The data came from a herd located in the Centro municipality, Tabasco, Mexico. Five NLM were evaluated: Wood (WOD), Wiltmink (WIL), Cobby (COB), Brody (BRO), Sikka (SIK). The best fit model was selected based on the mean prediction error, mean absolute percentage error (MAPE), prediction error variance, coefficient of determination (R2), concordance correlation coefficient (CCC), Akaike (AIC) and Bayesian (BIC) information criteria. A regression analysis was performed between the observed and predicted values. All the NLM had a R2 above 0.91. They tend to underestimate the predictions, without residual autocorrelation. The MAPE showed an average value of 23.5%. The best fit model was WOD, followed by SIK and BRO. For WIL and COB, the mixed model did not improve the fitting. The shortest lactation period showed the best fit, followed by the 210 d and 240 d periods. The relationship between observed:predicted values fluctuated from 0.65 to 1.00, with an average value of 0.94. The use of NLM transcended in the AIC and BIC. The evaluated models showed goodness of fit, with good predictability, but low values in accuracy and precision of prediction.

Abstract The objective of this work was to develop a monitoring network of temperature, humidity and air quality in a data center to automate the on and off switching of the cooling, ventilation and air filtering system using IoT (Internet of Things). A network with long-range wireless technology was implemented, consisting of five slave nodes, a master node and a user interface. The slave nodes periodically transmit the value of the three environment variables to the master node. The master node sends the information received from the slaves to a cloud server, so that it can be accessed from a user interface. When the value of any of the variables reaches the configured threshold, the cooling, ventilation and/or filtering system is activated as required. The tests showed that an accuracy of less than ±1.0 °C was obtained in the measurement of temperature, less than ±2 % in the measurement of humidity, less than ±8 µg/m3 in the measurement of air quality and a range of 11.5 kilometers with line of sight was achieved in data transmission over the network. Based on these results, the network can be implemented to monitor sensors and processes in other facilities with this scope.

Abstract This paper presents the construction of a prototype of a door and window monitoring system through an IoT platform. The objective was to design a system that reports to a server in the cloud the change of state, open or closed, of three doors and two windows of the equipment room of the data center. The changes of state are registered by the server and by means of a user interface the status of doors and windows is displayed online. The architecture of the system is based on a wireless sensor network integrated by a central node and five monitoring nodes. The monitoring nodes consist of a PyBoard card, two digital Hall effect sensors and a WiFi wireless interface. When detecting a change of state in doors and windows, the monitoring nodes notify it to the central node, and this transmits it to the server through a WiFi access point. When a door or window remains open for more than a configurable period of time, an SMS and WhatsApp message is sent to a mobile phone. The reach achieved in the WiFi transmission on the network was 47 meters with line of sight.

Resumen En este trabajo se presenta la construcción de un prototipo de un sistema de monitorización de puertas y ventanas a través de una plataforma IoT. El objetivo fue diseñar un sistema que reporte a un servidor en la nube el cambio de estado, abierta o cerrada, de tres puertas y dos ventanas de la sala de equipos del centro de datos. Los cambios de estado son registrados por el servidor y por medio de una interfaz de usuario se muestran en línea los estados de las puertas y ventanas. La arquitectura del sistema se basa en una red inalámbrica de sensores integrada por un nodo central y cinco nodos de monitorización. Los nodos de monitorización están compuestos por una tarjeta PyBoard, dos sensores digitales de efecto Hall y una interfaz inalámbrica wifi. Al detectar un cambio de estado en puertas y ventanas, los nodos de monitorización lo notifican al nodo central, y este lo transmite al servidor por medio de un punto de acceso wifi. Cuando una puerta o ventana permanece abierta más de un período de tiempo configurable, se envía un mensaje SMS y de WhatsApp a un teléfono móvil. El alcance logrado en la transmisión wifi en la red fue 47 metros con línea de vista.

ABSTRACT In the present work, two new generalized weighted methods of imputation of missing data are developed and tested using a daily rainfall series. The proposed methodology allows to fully rebuild the time series while preserving its statistical properties. Rainfall records in the state of Tabasco, Mexico, during the period 1980-2012 were used to test and evaluate the proposed methodology. The imputation of missing data in a given weather station is performed by using daily data from neighboring stations with a similar rainfall behavior. The choice of optimal parameters for the proposed formulae is based on minimizing the mean absolute error (MAE) via an evolutionary strategy (CMA-ES). The K-means method was used with the Euclidean distance in order to select the adequate neighboring weather stations. Five different methods were applied to estimate the optimal number of clusters: the elbow method, gap statistics, TraceW, Hartigan and Krzanowski-Lai indices. In addition, the structural stability of the chosen clusters was evaluated in order to demonstrate that these represent the correct data structure and are not the result of an artificial internal procedure of the grouping algorithm. Results from two different statistical tests, Friedman and Nemenyi post hoc, showed that our two new methods produce significantly and statistically better estimation when compared to existing methods in the literature.

RESUMEN En el presente trabajo se desarrollaron y probaron dos métodos generalizados ponderados de imputación de los valores de datos faltantes, utilizando para ello series diarias de precipitación. Se usaron registros de precipitación del estado de Tabasco, México, del periodo 1980-2012, para probar y evaluar la metodología propuesta. La imputación de datos faltantes en una estación meteorológica determinada se realizó utilizando información diaria de estaciones cercanas con patrones similares de precipitación. La selección de parámetros óptimos para las fórmulas propuestas se basó en la minimización del error medio absoluto mediante una estrategia evolutiva (CMA-ES). Se utilizó el método de K-medias junto con la distancia euclidiana para elegir las estaciones meteorológicas cercanas adecuadas. Se aplicaron cinco métodos diferentes para estimar el número óptimo de clústeres: el método de Elbow, la estadística de Gap y los índices TraceW, de Hartigan y de Krasnowski-Lai. Adicionalmente, se evaluó la estabilidad estructural de los clústeres seleccionados para demostrar que representan la estructura de datos correcta y no son resultado de un procedimiento interno artificial del algoritmo de agrupación. Los resultados de dos pruebas estadísticas, Friedman y Nemenyi post hoc, mostraron que los dos nuevos métodos presentados, producen estimaciones estadísticas significativamente mejores en comparación con otros métodos encontrados en la literatura.

Abstract Characterizing growth in livestock is important when making management, marketing and genetic improvement decisions. Nonlinear models were tested to identify those with the best fit for growth curves in seven sheep breeds [Blackbelly (n= 19,084); Pelibuey (n= 39,025); Dorper (n= 35,814); Katahdin (n= 74,154); Suffolk (n= 10,267); Hampshire (n= 7,561); and Rambouillet (n= 7,384)]. Using breed registry databases, live weight was assessed from birth to 230 d of age. The SAS program was applied to test six nonlinear models: Brody, Verhulst, von Bertalanffy, Gompertz, Mitscherlich and logistic. The criteria for selecting the best-fit model were the average prediction error; the prediction error variance; the Durbin-Watson statistic; the coefficient of determination; the root-mean-square error; and the Akaike and Bayesian information criteria. For the Hampshire, Pelibuey and Suffolk breeds the best-fit model was the von Bertalanffy, with a sigmoid curve and an inflection point age between 40 and 57 d. For the Katahdin, Blackbelly, Dorper and Rambouillet breeds the best-fit models were the Brody and Mitscherlich models, with a continuous growth curve, no inflection point and constant growth rate. Marked differences were observed in adult weight between breeds, with average values (kg) of 44.6 for Blackbelly, 49.2 for Rambouillet, 52.9 for Pelibuey, 55.6 for Hampshire, 60.2 for Katahdin, 64.7 for Suffolk and 65.2 for Dorper; values tended to be highest in the Brody and Mitscherlich models, and lowest in the logistic and Verhulst models.

Resumen Caracterizar el crecimiento ayuda en la toma de decisiones de manejo, comercialización y mejoramiento genético. El objetivo fue identificar un modelo no lineal (MNL) para describir la curva de crecimiento en borregas de registro a través de siete razas. Se evaluó el peso vivo, desde el nacimiento hasta los 230 d de edad, de las razas Blackbelly (BB; n= 19,084), Pelibuey (PE; n= 39,025), Dorper (DR; n= 35,814), Katahdin (KT; n= 74,154), Suffolk (SF; n= 10,267), Hampshire (HS; n= 7561) y Rambouillet (RB; n= 7,384). Se evaluaron los MNL: Brody (BRO), Verhulst (VER), Von Bertalanffy (VBE), Gompertz (GOM), Mitscherlich (MIT) y Logístico (LOG). Los análisis se realizaron con el software SAS. Los criterios para seleccionar el modelo con mejor ajuste fueron: error de predicción promedio, varianza del error de predicción, estadístico Durbin-Watson, coeficiente de determinación, raíz del cuadrado medio del error, criterios de información Akaike y Bayesiano. Para HS, PE y SF, el mejor modelo fue VBE, con una curva sigmoide y edad al punto de inflexión entre 40 y 57 d. Los modelos BRO y MIT tuvieron el mejor ajuste para KT, BB, DR y RB, con una curva continua, sin punto de inflexión y tasa de crecimiento constante. Para peso adulto se observaron marcadas diferencias, con valores promedio (kg) de 44.6 en BB, 49.2 en RB, 52.9 en PE, 55.6 en HS, 60.2 en KT, 64.7 en SF y 65.2 en DR; con la tendencia de valores mayores para los modelos BRO y MIT, y los menores para LOG y VER.

Abstract This paper presents the development of an access system to a data center using a RFID card and verification of the user's face. The system consists of three input modules and a central module. The objective was to design a system to transmit, from each input module to the central module, the universal unique identifier of the RFID card or UUID for its acronym in English and the user's face image to consult in a MySQL database and in a directory of photographs if the user can access the corresponding area of the input module. Each input module consists of a Raspberry Pi 3 B+ card, an RFID card reader, a video camera and a liquid crystal display or LCD for its acronym in English. The central module is composed of the same elements as the input modules and has a touch screen used in the user interface instead of an LCD screen. The communication between the nodes is WiFi, achieving a precision of 99.2% in the verification of the face and a response time of 180 ms using 310 trained photographs.

Resumen En este trabajo se presenta el desarrollo de un prototipo de sistema de acceso a un centro de datos usando como identificación una tarjeta de radio frecuencia o RFiD y verificación del rostro del usuario. El sistema se compone de tres módulos de entrada y un módulo central. El objetivo fue diseñar un sistema para transmitir, desde cada módulo de entrada al módulo central, el identificador único universal de la tarjeta RFiD o UUID y la imagen del rostro del usuario para consultar en una base de datos MySQL y en un directorio de fotografías si el usuario puede acceder al área correspondiente del módulo de entrada. Cada módulo de entrada consta de una tarjeta Raspberry Pi 3 B+, un lector de tarjetas RFiD, una cámara de video y una pantalla de cristal líquido o LCD. El módulo central se compone de los mismos elementos que los módulos de entrada y cuenta con una pantalla táctil usada en la interfaz de usuario en lugar de una pantalla LCD. La comunicación entre los nodos es wifi, logrando una precisión del 99,2 % en la verificación del rostro y un tiempo de respuesta de 180 ms usando 310 fotografías entrenadas.

ABSTRACT The objective of this study was to evaluate the effect of a mixture of direct-fed microbials (DFM), yeast, and digestive enzymes on animal performance in feedlot cattle, as well as digestibility when finishing feedlot cattle. Thirty crossbreed (Charolais × Beefmaster) steers averaging 15 months old and 321.83±3.73 kg of initial body weight were used. Animals were randomly assigned to one of two treatment groups: control (basal diet) and a mixture of DFM, yeast, and digestive enzymes (basal diet + 30 g of the mixture). Each group contained fifteen experimental units. Animals were fed individually twice a day, and dry matter intake (DMI) was recorded daily. Body weights were recorded initially and subsequently at 28-day intervals for a total of 140 days to evaluate average daily gain (ADG). The gain:feed ratio (G:F) was also calculated per period. Dry matter digestibility, crude protein (CPD), and neutral detergent fiber (NDFD) were evaluated in the finishing phase. Ten steers per treatment were randomly selected for digestibility evaluations. Insoluble acid detergent fiber was used to calculate apparent digestibility. A completely randomized design with measurements repeated over time was used to evaluate animal performance, and a completely randomized design was used to evaluate apparent digestibility. No effect of treatment was observed for DMI. At the end of the trial, differences for ADG were found between treatments, with higher values in control than the treatment group. However, no effect for G:F was found. Dry matter digestibility, CPD, and NDFD were similar between treatments. The addition of the mixture of DFM, yeast, and digestive enzymes as a feed supplement in the diet of feedlot cattle does not improve animal performance and nutrient digestibility.

ABSTRACT The objective of this study was to evaluate the effect of three levels of cull pinto beans (CPB) on animal performance, energy balance, and digestibility of hair ewes during pregnancy-lactation. One hundred and sixty-eight Pelibuey ewes were used (105 multiparous and 63 primiparous). Seven ewes of each type were randomly assigned to each of the 24 pens. Then, the twenty-four pens were randomly assigned to one of three treatments. Treatments were assigned on DM basis at: 0 g kg−1 of CPB in the supplement; 250 g kg−1 of CPB in the supplement; and 500 g kg−1 of CPB in the supplement. Data was analyzed by using the PROC MIXED of SAS. Lamb birth and weaning weight were also evaluated with the GLM procedure of SAS. All variables were analyzed as a completely randomized design. No differences among treatments were observed for body weight, body condition score, non-esterified fatty acids, and body weaning weight. During late pregnancy, dry matter intake was different among treatments, but it was similar during lactation. Body birth weight was different among treatments and showed a quadratic effect. At day 30 of lactation, a treatment effect was found for digestibility of dry matter (DM). At the end of lactation, digestibility of crude protein was different among treatments. In day 60 of lactation, differences among treatments were found for digestibility of neutral detergent fiber. Due to equal ewe performance among treatments of CPB and its low cost, its use is recommended in hair ewe feeding for these productive stages: 500 g kg−1 DM of the supplement during pregnancy and 400 g kg−1 DM during lactation.

ABSTRACT The objective was to evaluate the effect of three levels of cull pinto beans (CPB; Phaseolus vulgaris) on ruminal fermentation, kinetics, and nutrient digestibility in hair lambs. Six cannulated lambs averaging 56.6±3.8 kg were used and were randomly assigned to one of three treatments. Treatments were: 0.0 kg kg−1 of CPB in the supplement (control); 0.25 kg kg−1 of CPB in the supplement (CB25); and 0.40 kg kg−1 of CPB in the supplement (CB40). Dry matter intake, ruminal pH, NH3, and volatile fatty acid (VFA) concentration, methane production, Kp (passage rate), MRT (mean retention time), and digestibility of dry matter, crude protein, and neutral detergent fiber were evaluated. Data were analyzed in a Latin square design, repeated in line, by MIXED procedure of SAS. Estimates used for Kp and MRT were obtained by a non-linear regression model (PROC NLIN). Dry matter intake was reduced by supplementation of CPB. No differences were found in ruminal pH or ruminal NH3. During the trial, differences were found for ruminal VFA concentration (mM), which were greater for the CB25 group. The propionate:acetate ratio was greater for the CB40 treatment. Methane production (mM/m) differed among treatments, but it was the greatest for the CB40 group. Passage rate (kg kg−1/h) and MRT (h) were similar among treatments and the digestibility (kg kg−1) of dry matter, crude protein, and neutral detergent fiber was not different among treatments. The inclusion of 0.25 kg kg−1 of CPB in the diet of hair lambs allows for appropriate nutrient digestion without affecting Kp and MRT and increases the molar proportion of the ability of VFA to maintain acetate:propionate ratio without increasing methane production.

ABSTRACT The objective was to evaluate the effect of cull pinto beans (CPB) (Phaseolus vulgaris) on performance of feedlot lambs. Seventy-two crossbred hair-breed lambs (Dorper × Pelibuey and Kathadin × Pelibuey) were used (75±6 days old and 18.7±3.89 kg of initial body weight). Animals were fed twice daily. Diets consisted of 20% alfalfa hay and 80% concentrate based on ground sorghum grain and were formulated to contain 17.9% crude protein and 2.60 Mcal/kg metabolizable energy. Treatments were (dry matter basis): no CPB (0%), 10% CPB, and 20% CPB. Lambs were blocked by body weight and treatments and arranged in a 2 × 3 arrangement of treatments. Body weights were recorded initially and subsequently at 14-day intervals for a total 70 number of days. Dry matter intake was recorded daily. Apparent dry matter digestibility was predicted using insoluble acid detergent fiber. Data were analyzed as a randomized complete block design. Final body weight and average daily gain decreased linearly with increasing CPB level and were greater for males than females. A level × gender interaction was observed for dry matter and crude protein digestibility. Data for hot carcass weight and cold carcass weight decreased linearly as CPB level increased and were greater for males. Carcass yield, longissimus muscle area, and dressing percentage were greater for males. Dressing percentage quadratically increased as CPB level increased. Cull pinto beans are a suitable ingredient for feedlot hair-breed lambs, but the inclusion of more than 10% of CPB level decreases animal performance.

In the context of the agri-food industry's dynamism and contradictions, small producers are encouraged to restructure their production by planting biofuel-oriented crops such as African palm. This article analyzes the processes of productive restructuring promoted by corporations and the State, as well as the actions that small producers have taken in a municipality with high social marginalization located in an agricultural export region in Chiapas. Social and environmental contradictions of this restructuring are analyzed, as well as its implications in terms of national food and agricultural development. The expansion of African palm cultivation accentuates social inequalities, degrades natural resources, uses a large amount of fossil energy, drives land concentration, weakens local food provision systems, and restricts small producers from generating greater value within the agri-food chain.

En el contexto del dinamismo y contradicciones del sector agroalimentario, en la actualidad los pequeños productores son impulsados a emprender una reestructuración de sus prácticas productivas, a través de la plantación de cultivos orientados a biocombustibles, como el de la palma africana. En este artículo se analizan los procesos de reestructuración productiva, promovida por corporaciones de distinto origen y por el Estado, y las acciones realizadas por pequeños productores en un municipio con alta marginación, localizado en una región agroexportadora de Chiapas. Se revisan las contradicciones sociales y ambientales de este cambio y sus implicaciones a futuro, en términos del desarrollo agrícola y alimentario nacional. La expansión de este cultivo acentúa las desigualdades sociales, degrada los recursos naturales, utiliza mucha energía fósil, impulsa la concentración de la tierra, debilita los sistemas locales de provisión de alimentos y reduce los márgenes del valor generado en la cadena agroalimentaria para los pequeños productores.