Methods developed for estimating hourly DWC from daily values proved reliable (mean absolute error less than 1☌). For DWC involving psychrometric variables, the probable error was shown to vary with measuring system and ambient conditions. We find for dry-bulb-related DWC that various data limitations are generally minimal (uncertainty less than 1☌)for a station if at least ten years of data are available. The final objective is to determine the frequency and duration of episodes during which the ASHRAE DWC are met or exceeded. The second objective is to develop methods to estimate the percentiles of hourly dry-bulb temperature from daily data and to estimate humidity-related design weather conditions when no humidity data are available. The first objective is to determine the error associated with typical data limitations, such as nonhomogeneous data, incomplete data, and insufficient data. The work is organized around three main objectives. In this research we examine the uncertainty associated with the design weather conditions (DWC) as found in the ASHRAE Handbook - Fundamentals. © 2015 American Society of Agricultural and Biological Engineers.
#Dew point measure how to
Example measurements from REMS research demonstrate how to incorporate a documented standard uncertainty for emissions. Significant (p 0.05) SSMRP systematic bias was found for most chambers therefore, correction for bias following the methods developed here is recommended. Mass recovered uncertainty contributed from 70.1% to 90.7% to SSMRP uncertainty, mass injected uncertainty contributed from 2.5% to 4.0%, and reproducibility contributed from 5.6% to 27.3%. The mean SSMRP for the six chambers ranged from 92.0% to 96.6% with absolute expanded uncertainties (∼95% confidence interval) ranging from 10.4% to 13.0%. Results from the subsystem evaluation verified that chambers were positively pressurized, maintained thermal environmental comfort, and resulted in no measurable leakage along the sampling path from the chamber to the gas analyzer. Uncertainty analysis conducted as a part of commissioning included propagation of instrument uncertainties, quantification of the variability in repeated tests, and identification of systematic errors. Integrity of the entire system was verified through a steady-state mass recovery percent (SSMRP) analysis, which compared the total mass measured by REMS (mass recovered) to the total mas injected from a certified reference (mass injected) during steady-state operation.
#Dew point measure verification
Subsystem assessments included verification of chamber positive pressurization, thermal environmental control performance, and integrity of the gas sampling system.
#Dew point measure series
Part II of this series describes REMS commissioning and documents the whole system and subsystem performance. Part I of this series provides the description and design evaluation of the newly developed REMS using uncertainty analysis tools. The Ruminant Emission Measurement System (REMS) supports research on the relationships between bovine nutrition, genetics, and management strategies by measuring eructated CH4 emissions from ruminal activity.
The results from the uncertainty analyses of derived and observed variables suggest that the use of derived dewpoint temperature and derived relative humidity involves risk because the uncertainties of modern dewpoint temperature and relative humidity sensors can create several degrees Celsius of error in the derived dewpoint temperature and several percent in the derived relative humidity. The method of uncertainty analysis, provided by the National Institute of Standards and Technology, is applied to calculate the uncertainties of an indirect measurement of derived dewpoint temperature and derived relative humidity. The derived dewpoint temperature and relative humidity are calculated using algorithms provided by the World Meteorological Organization.
This paper presents an evaluation of derived dewpoint temperature and derived relative humidity, in which the dewpoint temperature is calculated using measured ambient air temperature and measured relative humidity variables and the derived relative humidity is calculated from measured dewpoint temperature.