Characterizing the strength of wood truss joints

Probability density functions (normal, lognormal, and three-parameter Weibull) were used to characterize strength data for three different types of metal-plate-connected wood truss joints (web at the bottom chord, tension splice, and heel). Modulus of elasticity (MOE) of the lumber used to fabricate the joints was also characterized. A probability-plot technique, in conjunction with Kolmogorov-Smirnov and chi-square statistics, was used to determine which distribution best fit the data. Lumber MOE was best described by a lognormal distribution. No single distributional form fit the strength data for all three joint types with equal accuracy. Lumber MOE and joint strength were unrelated. Strength data for the web at the bottom chord and heel joints were best described by normal distributions; however, none of the distributions considered fit the data for the tension splice joints. The probability-plot technique provided a better visual inspection of fit than did a density function superimposed over a histogram. Fitted distributions are easy to work with and can be used in reliability analyses to simulate strength values of joints. The results presented here are for particular joint types and plates and should not be extrapolated to other truss joints

Economically sustainable shade design for feedlot cattle

Provision of shade reduces radiant heat load on feedlot cattle, thus reducing demand of water and energy for thermoregulation. While the positive effects of shade on animal welfare are widely known, the literature lacks data on the magnitude of its economic impacts. In this study, we propose the concept of novel shade design to prove that a correctly oriented and dimensioned roof structure, which optimizes shade to be displaced within the pens, motivates cattle to seek shade, protect them from short-wave solar radiation, and is resilient to counteract weather adverse conditions. The beneficial outcome is improvement in animal welfare and productive performance, as well as increments on financial return and sustainability. To attest these benefits, eight hundred B. indicus × Bos taurus bulls were randomly assigned in pens with or without shade from a galvanized steel-roof structure. Performance data (e.g., dry matter intake, body weight gain, feed efficiency and hot carcass weight) and heat stress indicators (e.g., subcutaneous temperature, body-surface temperature, respiratory rate and water intake) were assessed along the study period. The economic outcomes derived from shade implementation were determined using the net present value. Meteorological variables were also monitored every 1 min, and grouped in a thermal comfort index for feedlot cattle, the InComfort Index (InCI). The shade structure efficiently reduced radiant heat load on cattle in pens with shade. According to the classification of the InCI, during very hot days (InCI > 0.6; around noon with mean solar radiation above 800 W m−2 and mean air temperature above 33°C), greater proportion (80%) of animals in shaded pens were using shade. Under such circumstances, cattle in shade had water intake reduced by 3.4 L per animal, body temperature was lower by 5°C, subcutaneous temperature was lower by 1°C and respiration rate was lower by 10 breaths min−1 compared to animals in pens without shade (P = 0.0001). Although dry matter intake was similar (P = 0.6805), cattle in pens with shade had higher average daily gain reflected in a heavier hot carcass weight (8 kg animal−1; P = 0.0002). Considering an initial investment of $90 per animal to build a structure that lasts 15 years, the expected payback time is four finishing cycles (~110 days per cycle). In conclusion, this study confirms that the proposed novel shade design is economically profitable, improves performance, and enhances animal welfare

Destructive testing of metal-plate-connected wood truss joints.

Load-displacement characteristics and failure modes of metal-plate­connected wood truss joints are presented. Tension splice, heel, and web at the bottom chord joints are fabricated using southern pine (SP) no. 2 lumber and 20-gage punched metal plates. These joints are tested with a newly developed testing appratus that allows the testing of all three joints without major modifications. In­plane loads are applied to simulate the loads carried by truss members. The com­puterized testing apparatus and methods show potential as an. efficient testing pro­cedure to assess joint behavior. The average strength of tension splice, heel, and web at the lower chord joints is 27.0 kN, 22.7 kN, and 16.7 kN, respectively. The failure of the heel joint is characterized as ductile, and that of the tension splice and web at the bottom chord joints as brittle. 'The failure of the joints is a combination of wood and teeth failure. The results are useful for semirigid joint analysis and design of metal-plate-connected wood trusses

Procedures for measuring 3-D surface area and surface temperature of livestock

<p>Bio-energetic models of livestock require geometrical properties (<i>e.g.</i>, surface area) of animals. Currently, the surface area of animals is estimated from empirical equations based on body weight or assuming the animal as cylinders or spheres. These approximations do not accurately characterize the true geometry of the animal. Similarly, skin-surface temperature predictions from bio-energetic models are validated by taking spot measurements, which neglects the spatial variability of this parameter. In this study, an accurate approach of measuring these parameters is proposed. Based on preliminary results (more data analysis is ongoing), the advantages and disadvantages of various 3-D scanning technologies (photogrammetry, Kinect V1, Kinect V2, Intel® RealSense™ SR300, and Intel® RealSense™ R200) as well as two different procedures for obtaining 3-D surface temperature (thermal projection and thermal photogrammetry) are discussed. Kinect (V1 or V2) is recommended for 3-D scanning of livestock because the sensors are cheap and easy to use. Sense from 3-D Systems (Intel® RealSense™ SR300) does not support large scanning volumes but it is recommended for scanning small animals (or parts of an animal) because it is handheld and the software is easy to use. To scan large animals (<i>e.g.</i>, a whole cow) and for advanced users, Intel® RealSense™ R200 is suitable. For 3-D surface temperature, thermal photogrammetry is recommended because it is less error prone than thermal projection. </p

Graded meshes in bio-thermal problems with transmission-line modeling method

In this study, the transmission-line modeling (TLM) applied to bio-thermal problems was improved by incorporating several novel computational techniques, which include application of graded meshes which resulted in 9 times faster in computational time and uses only a fraction (16%) of the computational resources used by regular meshes in analyzing heat flow through heterogeneous media. Graded meshes, unlike regular meshes, allow heat sources to be modeled in all segments of the mesh. A new boundary condition that considers thermal properties and thus resulting in a more realistic modeling of complex problems is introduced. Also, a new way of calculating an error parameter is introduced. The calculated temperatures between nodes were compared against the results obtained from the literature and agreed within less than 1% difference. It is reasonable, therefore, to conclude that the improved TLM model described herein has great potential in heat transfer of biological systems.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

A Repository of Big Data Sets for Computer Vision and Machine Learning Applications in Precision Livestock Farming

&lt;p&gt;&lt;span&gt;A Precision Livestock Farming repository of Big Data sets for computer vision and machine learning applications (PLFBD).&lt;/span&gt;&lt;/p&gt

Use of Solar Panels for Shade for Holstein Heifers

Animal Agrivoltaics combines electric energy generation, animal thermal comfort, and sustainable production at the same time. This model of production can foster the sustainable intensification of dairy production in tropical areas where solar irradiance is high and nearly constant throughout the year. In this study, we propose Animal Agrivoltaics as an alternative practice to reduce the heat load and eCH4 emissions from dairy heifers in tropical areas. To attest this hypothesis, (1) the meteorological data and the behavioral and physiological responses of the animals were integrated in order to determine the benefits provided by the shade from the solar panels on the thermoregulation of the dairy heifers, and (2) measurements of the enteric methane emissions were taken to determine the potential of the solar panels to offset the GHG. Seven crossbred Holstein heifers (7/8, Holstein &times; Gyr) with a mean body weight of 242 kg (SD = 53.5) were evaluated in a paddock shaded with ten modules of solar panels. Miniature temperature loggers were used to record the body surface, skin and vaginal temperatures of the heifers every five minutes. The respiratory rate and the shade-use behavior were also monitored by two observers. These measurements were taken from 08:00 to 17:00 h for 18 consecutive days. After completing the field study, the heifers underwent for assessments of the daily oscillations of eCH4 emission using a flow-through respirometry system. The use of shade by the heifers was progressively increased (p &lt; 0.01) with an increasing level of solar irradiance. Lying and ruminating were more likely (p &lt; 0.01) to occur when the heifers were in the shade, especially when the solar irradiance exceeded 500 W m&minus;2. Between 10:00 and 14:00 h, the heifers benefited from the shade produced by the solar panels, with a reduction of 40% in the radiant heat load. With an increasing intensity of solar irradiance, body surface temperature, skin temperature and respiratory rate of the heifers in the shade were lower (p &lt; 0.01) compared to when they were exposed to the sun. The heifers had a daily methane emission total of 63.5 g per animal&minus;1 or 1.7 kg of CO2-eq. Based on this emission rate and the amount of CO2-eq that was not emitted to the atmosphere due to the electricity generated by solar panels, 4.1 m2 of panels per animal (nominal power = 335 W) would be expected to obtain a net-zero eCH4 emission. Over a period of one year (from September 2018 to August 2019), a set of ten photovoltaic panels used in the study produced 4869.4 kWh of electricity, thereby saving US $970.00 or US$48.00 per m2 of solar panel. Based on the results of this study, it can be concluded that use of Animal Agrivoltaics, in addition to producing electricity, has significant potential benefit in providing better thermal comfort to cattle, as well as offsetting the enteric methane emissions released into the environment. In addition, the system would provide extra income to farmers, as well as a potential source of energy micro-generation