The experimenter occasionally encounters high-frequency (> 1 Hz) contamination in sonic anemometer data that adversely affects higher-order moment calculations. One has the option of applying a low-pass filter (either a simple, equally weighted moving average filter or any one of the sharper cut-off versions available today) to eliminate not only the unwanted frequency, but all frequencies above it as well. A band rejection or notch filter would be a better choice because of its selectivity, but is seldom used because of computational complexity. In many instances the contamination is quasi-sinusoidal, often caused by vibration of the supporting boom at a frequency typically between 1 and 2 Hz. A simple procedure exists for removing such noise without seriously degrading the signal. It is a notch filter, realized by averaging data points spaced τ/2 apart in time, where τ is the period of the noise signal.
- Applied Technologies, Inc. (ATI)
- A simple notch filter for removing high frequency noise in ...
Introducing The RNRG Goalpost Boom
We are happy to introduce a new goalpost mounting solution for installing redundant class 1 anemometers. This new boom, designed specifically for use with our 80m XHD TallTower, positions anemometer cups at exactly 80 m above ground level—2.5 m away from each other—and 1.99 m above the horizontal arm of the boom. This configuration complies with guidelines provided in Annex G of the IEC 61400-12-1:2005 standard when installed on a RNRG 80m XHD TallTower—a solution that is well-suited for conductin...
Luminant Oak Grove Power Station - Case Study
Powering Texas Luminant, a subsidiary of Energy Future Holdings Corp. (EFH) -which owns competitive and regulated energy subsidiaries in Texas -is the largest electricity generator in Texas. Unit two of the Oak Grove Power plant near Franklin in Robertson County, TX went online in the middle of 2010. Fluor, the project’s EPC company, completed the plant in 35 months and used advanced control technologies to make the Oak Grove super-critical generating station one of the cleanest coal-fired power plants in...
Metek Introduces the New Multi-Path Ultrasonic Anemometers
Our news report about recent instrumentations or measurements of our customers which might be of special interest for other web site visitors. The reports are added on the fly whenever we have received such information. The experienced support is highly welcome and appreciated. Metek is proud to present the new members of the uSonic-family: The ultrasonic anemometers uSonic-3 Class A MP and uSonic-3 Cage MP represent an innovative step forward to highest performance in atmospheric turbulence sounding. Based on...
Validation of computational non-Newtonian fluid model for membrane bioreactor
Membrane bioreactor (MBR) systems are often considered as the wastewater treatment method of the future due to their high effluent quality. One of the main problems with such systems is a relative large energy consumption, compared to conventional activated sludge (CAS) systems, which has led to further research in this specific area. A powerful tool for optimizing MBR-systems is computational fluid dynamics (CFD) modelling, which gives researchers the ability to describe the flow in the systems. A parameter...
Case Study Port of Hamburg/Germany
LOG_aLevel Storm Tide Network at the Port of Hamburg, GermanySince 2003 a Storm Tide Network from General Acoustics GmbH (GA) has been satisfactory operating at the Port of Hamburg. In a first test phase of two years a LOG_aLevel station was successfully tested by the Hamburg Port Authority (HPA) against its conventional gauges. Due to the good results in terms of accuracy and robustness obtained with LOG_aLevel, HPA decided to set up a measuring network of stations from GA. In the current operational phase a...