Igor M. Lopes

DETERMINAÇÃO DA MATRIZ DE RIGIDEZ DO CONCRETO UTILIZANDO ULTRASSOM

The determination of the modulus tangent (Eci ) and of the modulus secant (Ecs) of the concrete can be done using compression test but, to be simpler, it is used relations with characteristic strength (fck). Relations are also used to determine the transversal modulus (Gc) and, in the case of the Poissons ratio (ν), a fixed value 0.20 is established. The objective of this research was to evaluate the use of the ultrasonic propagation waves to determine these properties. For the tests were used specimens with fck varying from 10 to 35 MPa. For the ultrasonic tests were used cylindrical and cubic specimens. The modulus of deformation obtained by ultrasound was statistically equivalent to the obtained by compression tests. The results of modules obtained using the relations with fck was far away from those obtained by ultrasound or by compression tests. The Poissons ratio obtained by ultrasound was superior to the fixed value. We can conclude that the concrete characterization by ultrasound is consistent and, to this characterization the cylindrical specimen, normally used to determine fck, can be used.

Assessing Air Leakage in Commercial Broiler Houses

The design and operation of broiler house ventilation are directly related to the air inlet characteristics. Air leakage affects the air distribution and mixing inside the houses causing negative effects on the inside air quality and environmental control. A common method of evaluating broiler house tightness is to entirely close the house, turn on a single 1.2m (48-inch) exhaust fan, and record the static pressure. A new procedure to assess broiler house tightness was developed. Fourteen air leakage curves (of the form **this equation is following the Introduction below***) from fourteen different broiler houses (located in the state of Kentucky) were developed by recording static pressure inside the house when different calibrated fans were turned on. A Fan Assessment Numeration System (FANS) was used for exhaust fan calibration. The air flow exponent (n) ranged from 0.35 to 0.74 (standard error varying from 0.02 to 0.12). The flow coefficient k (m3s-1Pa-n) ranged from 0.55 to 3.55 (standard error varying from 0.1 to 0.45). The results show substantial variability among Kentucky broiler houses.

Influence of fan operations on FANS (Fan Assessment Numeration System) test results

The FANS (Fan Assessment Numeration System) Unit is a device, originally developed and constructed by the URSDA-ARS Southern Poultry Research Laboratory and refined at University of Kentucky, to measure in-situ air flow of exhaust ventilation fans. The FANS Unit has been adopted as a standard method of measuring fan airflow at different static pressures in livestock barns for numerous field research projects. However, procedures for using FANS to conduct in-situ fan tests are not completely standardized. One procedure for changing the static pressure is turning on and off different fans inside the barn. Still, it is not known if the FANS Unit may affect the results of a fan tested in-situ when different fans are operating simultaneously. Therefore, this project aimed to determine if the operation of different fan combinations during an in-situ fan performance test would affect results obtained from the FANS unit. Tests were conducted in eight tunnel ventilated broiler houses, in which one (1.22 m) exhaust fan per barn was chosen for repeated testing while different combinations of fans were operating. The combinations were: FANS unit in the upstream position; FANS unit between adjacent operating fans in the upstream and downstream positions (Middle position); FANS unit at the tested fan operating alone, with no other fans operating. Results showed that the air flow was up to 20% higher, when testing a fan with no other fans operating, than the air flow from the same fan tested with FANS in an upstream position. Air flow was also up to 16% higher with the FANS unit in the Middle position than when the same fan was tested with the FANS unit in the upstream position. A smaller difference range (-5.4% to 3.9%) was also found between the test results from FANS with no other fans operating and FANS in the Middle position.

Calibration Drift Assessment and Upgrades to the Fan Assessment Numeration System (FANS)

Aerial emissions from animal feeding operations have been a growing concern for rural residents in the U.S. In order to accurately quantify emissions from a livestock facility, the ventilation rates of each fan operating at a facility are needed. One means of providing this information is to create an in-situ calibration for each fan. The original Fans Assessment Numeration System (FANS) was developed for this purpose. Since the first generation FANS units were released major improvements have been made to improve their efficiency and reliability. The purpose of this paper is to outline the new enhancements made to the fourth generation (G4) FANS units and compare the performance of the fourth generation to its predecessors. The most recent updates included a faster travel rate, sealed limit switches, and an adjustable chain tensioning mechanism. In addition to the hardware updates on each of the new units, the FANS software was updated to include Bluetooth wireless connection capabilities, real-time anemometer RPM and estimated ventilation rate readouts. Four newly manufactured G4 FANS units were calibrated and compared to previous generations of the FANS units. A calibration drift assessment was also performed on select individual FANS units over a ten-year period, which found the absolute accuracy of the FANS units do not fluctuate over time unless there are mechanical malfunctions occurring within the FANS device.

Visualizing Airflow Using the Fan Assessment Numeration System (FANS)

A filtering and interpolation technique was investigated for generating 2-D contour plots from raw Fan Assessment Numeration System (FANS) data. Airflow data was acquired at average static pressures varying from 4.4 Pa to 51.7 Pa. High frequency noise was removed using a digital low-pass filter prior to interpolation using a bi-cubic method. The cutoff frequency of the low-pass filter was shown to have a large effect on the amount of noise present in the 2-D contour plot as well as how well trends were preserved. A cutoff frequency of 0.1 Hz was determined to be adequate removing enough system noise without distorting the underlying process. The shape of the airflow distribution was consistent throughout all static pressure tests and could simply be scaled to compensate for static pressure.