Brett C. Ramirez

Omnidirectional thermal anemometer for low airspeed and multi-point measurement applications

Display Omitted An anemometer system was developed for multipoint measurements in livestock housing.Extensive uncertainty analysis was performed through entire measurement process.Suitable performance for low airspeed measurements at temperatures in animal housing.Inexpensive discretized assessment of thermal environment of livestock is possible. Current control strategies for livestock and poultry facilities need to improve their interpretation of the Thermal Environment (TE) that the animals are experiencing in order to provide an optimum TE that is uniformly distributed throughout the facility; hence, airspeed, a critical parameter influencing evaporative and convective heat exchange must be measured. An omnidirectional, constant temperature, Thermal Anemometer (TA) with ambient dry-bulb temperature (tdb) compensation was designed and developed for measuring airspeeds between 0 and 6.0ms-1. An Arduino measured two analog voltages to determine the thermistor temperature and subsequently the power being dissipated from a near-spherical overheated thermistor in a bridge circuit with a transistor and operational amplifier. A custom wind tunnel featuring a 0.1m diameter pipe with an access for TA insertion was constructed to calibrate the TA at different temperatures and airspeeds, at a constant relative humidity. The heat dissipation factor was calculated for a given airspeed at different ambient temperatures ranging from 18°C to 34°C and used in a unique fourth-order polynomial regression that compensates for temperature using the fluid properties evaluated at the film temperature. A detailed uncertainty analysis was performed on all key measurement inputs, such as the microcontroller analog to digital converter, TA and tdb thermistor regression statistics, and the calibration standard, that were propagated through the calibration regression. Absolute combined standard uncertainty associated with temperature corrected airspeed measurements ranged from 0.11ms-1 (at 0.47ms-1; 30.3% relative) to 0.71ms-1 (at 5.52ms-1; 12.8% relative). The TA system cost less than

Effects of Number of Animals Monitored on Representations of Cattle Group Movement Characteristics and Spatial Occupancy

35USD in components and due to the simple hardware, this thermal anemometer is well-suited for integration into multi-point data acquisition systems analyzing spatial and temporal variability inside livestock and poultry housing.

Control algorithm development and simulation for comparing evaporative pads and sprinklers for grow-finish pigs

The number of animals required to represent the collective characteristics of a group remains a concern in animal movement monitoring with GPS. Monitoring a subset of animals from a group instead of all animals can reduce costs and labor; however, incomplete data may cause information losses and inaccuracy in subsequent data analyses. In cattle studies, little work has been conducted to determine the number of cattle within a group needed to be instrumented considering subsequent analyses. Two different groups of cattle (a mixed group of 24 beef cows and heifers, and another group of 8 beef cows) were monitored with GPS collars at 4 min intervals on intensively managed pastures and corn residue fields in 2011. The effects of subset group size on cattle movement characterization and spatial occupancy analysis were evaluated by comparing the results between subset groups and the entire group for a variety of summarization parameters. As expected, more animals yield better results for all parameters. Results show the average group travel speed and daily travel distances are overestimated as subset group size decreases, while the average group radius is underestimated. Accuracy of group centroid locations and group radii are improved linearly as subset group size increases. A kernel density estimation was performed to quantify the spatial occupancy by cattle via GPS location data. Results show animals among the group had high similarity of spatial occupancy. Decisions regarding choosing an appropriate subset group size for monitoring depend on the specific use of data for subsequent analysis: a small subset group may be adequate for identifying areas visited by cattle; larger subset group size (e.g. subset group containing more than 75% of animals) is recommended to achieve better accuracy of group movement characteristics and spatial occupancy for the use of correlating cattle locations with other environmental factors.

Thermal environment assessment and controller performance comparison for a wean-finish barn

Seasonal variability attributed to heat stress (HS) has a large economic impact on the US swine industry by reducing daily gain and finishing market weights. Strategies to mitigate HS lack evidence showing effectiveness in different climates and have not been adequately controlled to provide a thermally optimum environment for pigs. Hence, the goal of this study was to describe the initial experimental design and instrumentation as well as develop innovative control algorithms for operating evaporative pads (EPs) and sprinklers. Located in northeast Iowa, a four room (~1,875 head per room) grow-finish facility featured sideby-side rooms separated by a hallway. Three thermal environment sensor arrays (TESAs) quantifying drybulb and globe temperature, relative humidity, and airspeed were placed in each room and served as feedback for control system to evaluate the thermal environment and potential HS conditions. The newly developed housed swine heat stress index (HS2I) combines TESA measurements and optional wetted skin to assess the potential for HS onset. Custom software interfaced with a multifunction data acquisition board was used to condition TESA signals and control EP pumps and sprinkler solenoids. A control algorithm was developed and simulated using data collected during a 23-d period in July 2017 to preliminarily evaluate the robustness and potential control decisions. Linear models developed to predict indoor dry-/wet-bulb temperature showed good agreement with measured data and will be critical for developing a control systems to selects the best cooling system given forecasted ambient conditions.

Development and evaluation of an evaporation model for predicting sprinkler interval time

The thermal environment (TE) inside swine facilities has a substantial impact on animal growth performance and facility energy usage; therefore, proper control and measurement are required to maintain the optimal TE that maximizes feed efficiency and consumes minimal resources. An inexpensive and novel network of 44 thermal environment sensor arrays (TESAs) capable of capturing the spatial and temporal distribution of the TE were deployed in August 2016 inside a two-room (designated as North; N and South; S), wean-finish barn (~1200 hd and 22 TESAs per room) and placed about 1.8 m above the slatted floor. All TESAs simultaneously measured and averaged 20 samples of dry-bulb temperature, back globe temperature, airspeed, and relative humidity at 1 min intervals. The objectives of this research were to: (1) summarize the TE observations from this monitoring period and (2) develop some preliminary analysis methods to quantitatively compare the TE in each room. Each room of the fully mechanically, power-tunnel ventilated facility featured independent TE control (i.e., fan, heater, inlet, and tunnel curtain operation) by a unique ventilation controller. A set point uniformity coefficient (γSP; binned by ambient temperature; ta) was used to assess ventilation controller performance and a two-sample (from random subsampling of ta bins) t-test was used to test if γSP in each room was statistically different. Results showed a statistically significant difference between N and S room γSP for ta bins8°C (p = 0.26; p = 0.07; p = 0.73; p = 0.31). This is a preliminary and novel approach to assessing ventilation controller performance and future approaches will need incorporate all parameters of the TE.

Design and Feasibility of an Impact-Based Odor Control System

Heat stress in swine causes decreased productivity and economic losses; hence, heat stress mitigation techniques must be developed to be economically and resource efficient. Current cooling strategies for livestock facilities, such as evaporative coolers or sprinklers, are governed by the Water Vapor Pressure (WVP) concentration gradient between the air (a function of dry-bulb temperature; tdb, Relative Humidity; RH, and atmospheric pressure) and the saturated WVP at the wet surface. Traditional sprinkler control systems operate at fixed ‘off ’ intervals (i.e., drying) regardless if the thermal environment (TE) has the capacity or not to evaporate the dispersed water. Therefore, the objectives were to develop and simulate a novel Variable Interval Sprinkler Control System (VISCoS) that dynamically changes the ‘off ’ interval based on tdb, RH, and airspeed feedback. A theoretical simplified pig evaporation model estimated water evaporation rate as a function of the TE, pig surface area and skin temperature, and mass of water applied. To evaluate the model in controlled conditions, a cylinder (assumed geometry of a pig) was placed inside an insulated enclosure where different combinations of tdb, RH, and airspeed could be simulated across the cylinder. The inside surface of the cylinder was heated and controlled to replicate the skin temperature of an animal, while the outer surface was wrapped in a thin chamois. Water was applied to the cylinder via a sprinkler where approximately 40% of the top portion of the cylinder was wetted. Comparison of modeled with measured evaporation time showed reasonable agreement with a root-mean-square error of 7.9 min for evaporation times ranging from 5 to 25 min.

A novel ruminant emission measurement system: Part I. Design evaluation and description

Abstract Legislation and rural communities are increasingly requesting reductions in odor emitted from swine production facilities. If odor is regarded solely as a nuisance, and not an environmental hazard (as in this research), such that the objective of treating ventilation exhaust air is to prevent odor from impacting nearby receptors, it is unnecessary to treat exhaust air when dispersed odor is not identifiable. This approach maximizes odor reduction potential when most needed, with economic benefit through decreased energy and resource usage by simply operating the mitigation device for less time. The objectives of this article were: to develop an on-off, real-time control system for on-farm odor mitigation devices and provide insight on the potential reduction in operation time of any odor mitigation strategy for climatic variability. The Impact Based Odor Control System (IBOCS) monitors wind speed, wind direction, and insolation to determine atmospheric stability, and utilizes location of nearby receptors relative to a facility to conclude if exhaust air requires treatment. A prototype of IBOCS was developed and consisted of an Arduino to execute the control algorithm and manage sensor measurements, receptor directional locations, and device activation or deactivation. The user interface included an eight-direction toggle switch indicator (i.e., receptor directional location), power switch, automatic/manual switch to override IBOCS, and additional tactile inputs for manual control. The feasibility of implementing IBOCS was evaluated at five simulated locations (MN, IA, MO, IN, and NC) in the United States by computing the reduction in annual mitigation device operation based on IBOCS logic from Typical Meteorological Year 3 data sets. Regardless of receptor location relative to a simulated facility site, IBOCS logic estimated annual mitigation technology operation to range from 64.4% (NC) to 71.4% (IN). Further, the minimum estimated annual operation ranged from 14.2% (IA) to 27.9% (MO) with only one receptor present. The overall goal of IBOCS is to reduce the impact of dispersed odor while concurrently decreasing operational expenses for expensive mitigation technologies.