scholarly journals Spectral shapes and parameters from three different wave sensors

2021 ◽  
Author(s):  
Anne Karin Magnusson ◽  
Robert Jensen ◽  
Val Swail
Keyword(s):  
Frequency Spectra ◽  
Measurement Systems ◽  
Wave Measurements ◽  
Climate Monitoring ◽  
Production Platform ◽  
Wave Sensors ◽  
Central North Sea ◽  
Wave Forecasting ◽  
Wave Properties

AbstractThe quality of wave measurements is of primary importance for the validation of wave forecasting models, satellite wave calibration and validation, wave physics, offshore operations and design and climate monitoring. Validation of global wave forecasts revealed significant regional differences, which were linked to the different wave buoy systems used by different countries. To fully understand the differences between the wave measurement systems, it is necessary to go beyond investigations of the integral wave parameters height, period and direction, into the frequency spectra and the four directional Fourier parameters that are used to estimate the directional distribution. We here analyse wave data measured from three different sensors (non-directional Datawell Waverider buoy, WaveRadar Rex, Optech laser) operating at the Ekofisk oil production platform located in the central North Sea over a period of several months, with significant wave height ranging from 1 to 10 m. In general, all three sensors provide similar measurements of the integral wave properties and frequency spectra, although there are some significant differences which could impact design and operations, forecast verification and climate monitoring. For example, the radar underestimates energy in frequency bands higher than 8 s by 3–5%, swell (12.5–16 s) by 5–13%, while the laser has 1–2% more energy than the Waverider in the most energetic bands. Lee effects of structures are also estimated. Lower energy at the frequency tail with the radar has an effect on wave periods (they are higher); wave steepness is seen to be reduced by 10% in the wind seas. Goda peakedness and the unidirectional Benjamin-Feir index are also examined for the three sensors.

scholarly journals Quantifying wave measurement differences in historical and present wave buoy systems

2021 ◽  
Author(s):  
Robert Edward Jensen ◽  
Val Swail ◽  
Richard Harry Bouchard
Keyword(s):  
Complex Nature ◽  
Frequency Spectra ◽  
Measurement Systems ◽  
Wave Measurements ◽  
Directional Sensors ◽  
Wave Measurement ◽  
Western Us ◽  
Directional Wave ◽  
Wind Sea ◽  
Wave Properties

AbstractAn intra-measurement evaluation was undertaken, deploying a NOMAD buoy equipped with three National Data Buoy Center and two Environment and Climate Change Canada-AXYS sensor/payload packages off Monterey, California; a Datawell Directional Waverider buoy was deployed within 19 km of the NOMAD site. The six independent wave measurement systems reported hourly estimates of the frequency spectra, and when applicable, the four Fourier directional components. The integral wave parameters showed general agreement among the five sensors compared to the neighboring Datawell Directional Waverider, with the Inclinometer and the Watchman performing similarly to the more sophisticated 3DMG, HIPPY, and Triaxys sensor packages. As the Hm0 increased, all but the Inclinometer were biased low; however, even the Watchman reported reasonable wave measurements up to about 6–7 m, after which the Hm0 becomes negatively biased up to about a meter, comparable to previous studies. The parabolic fit peak spectral wave period, Tpp, results showed a large scatter, resulting from the complex nature of multiple swell wave systems compounded by local wind-sea development, exacerbated by a variable that can be considered as temporally unstable. The three directional sensors demonstrated that NOMAD buoys are capable of measuring directional wave properties along the western US coast, with biases of about 6 to 9 deg, and rms errors of approximately 30 deg. Frequency spectral evaluations found similarities in the shape, but a significant under estimation in the high frequency range. The results from slope analyses also revealed a positive bias in the rear face of the spectra, and a lack of invariance in frequency as suggested by theory.

scholarly journals Quantifying the Effects of Vibration on Medicines in Transit Caused by Fixed-Wing and Multi-Copter Drones

Drones ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 22
Author(s):  
Andrew Oakey ◽  
Tim Waters ◽  
Wanqing Zhu ◽  
Paul G. Royall ◽  
Tom Cherrett ◽  
...  
Keyword(s):  
Road Transport ◽  
Uv Spectra ◽  
Frequency Spectra ◽  
Vibration Measurements ◽  
British Pharmacopoeia ◽  
Medical Products ◽  
Industry Standard ◽  
The Stability ◽  
In Transit

The concept of transporting medical products by drone is gaining a lot of interest amongst the medical and logistics communities. Such innovation has generated several questions, a key one being the potential effects of flight on the stability of medical products. The aims of this study were to quantify the vibration present within drone flight, study its effect on the quality of the medical insulin through live flight trials, and compare the effects of vibration from drone flight with traditional road transport. Three trials took place in which insulin ampoules and mock blood stocks were transported to site and flown using industry standard packaging by a fixed-wing or a multi-copter drone. Triaxial vibration measurements were acquired, both in-flight and during road transit, from which overall levels and frequency spectra were derived. British Pharmacopeia quality tests were undertaken in which the UV spectra of the flown insulin samples were compared to controls of known turbidity. In-flight vibration levels in both the drone types exceeded road induced levels by up to a factor of three, and predominant vibration occurred at significantly higher frequencies. Flown samples gave clear insulin solutions that met the British Pharmacopoeia specification, and no aggregation of insulin was detected.

scholarly journals Optimal Transmit Volume Conditions for Mission Critical Voice Quality of Experience Measurement Systems

2021 ◽  
Author(s):  
Chelsea Greene ◽  
Jesse Frey ◽  
William Magrogan ◽  
Cara O’Malley ◽  
Jaden Pieper
Keyword(s):  
Quality Of Experience ◽  
Voice Quality ◽  
Measurement Systems ◽  
Mission Critical

Twenty-Five Years of Pavement Smoothness Specifications in Georgia

1996 ◽  
Vol 1545 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Ronald Collins ◽  
Wouter Gulden ◽  
Dan R. Brown
Keyword(s):  
South Dakota ◽  
Mix Design ◽  
Response Type ◽  
Department Of Transportation ◽  
The Public ◽  
Measurement Systems ◽  
Construction Specifications ◽  
Pavement Construction

The traveling public generally recognizes the smoothness of a pavement as a major indicator of quality. A newly constructed pavement can have excellent materials, mix design, compaction, and so forth, but if the public considers the ride rough, the quality is considered poor. While continually striving to improve the quality of paving materials in mix designs, the Georgia Department of Transportation (GDOT) began an effort in 1968 to attain the ability to accurately measure the smoothness of a pavement so that this indicator of quality could be measured and specified during construction. GDOT has been using response-type smoothness-measurement systems in its construction specifications for acceptance of projects since 1972 and since 1979 for both rejection and acceptance. The evolution of the pavement smoothness-measuring program in Georgia, the program operating procedures, and the current smoothness specifications are described. The long-term benefits of smoothness specification for pavement construction are also discussed, as is GDOT's effort to replace the Mays Meter trailer systems currently used with South Dakota–type, laser-based road profilers.

Benchmarking Experiments for Wave Absorption Modeling

2015 ◽  
Author(s):  
Allan R. Magee ◽  
Varjola Nelko ◽  
Kian Yew Lim ◽  
Lup Wai Chew
Keyword(s):  
Absorption Efficiency ◽  
Numerical Wave Tank ◽  
Wave Absorption ◽  
Wave Flume ◽  
Dissipative Effects ◽  
Laboratory Flume ◽  
Laboratory Investigations ◽  
Numerical Wave ◽  
Wave Properties

Passive wave absorption is usually employed at the downstream end of a wave flume or basin to avoid the build-up of wave energy in the tank. However, absorption of waves is not perfect in physical tanks. A beach of different shape and/or composition can result in different absorption efficiency. Laboratory investigations of various passive beach configurations are costly and time-consuming. A more efficient approach is to perform studies using a numerical wave tank (NWT), which in turn requires empirical data to tune the dissipative effects. This study attempts to better understand the quality of waves simulated in a laboratory flume with a uniformly inclined porous beach and a parabolic-shaped solid beach. The data will be used to validate a newly-developed NWT with passive wave absorption. Different incident wave properties are examined and the reflection coefficient is calculated primarily with the two-probe method proposed by Goda & Suzuki (1976) and compared with other methods. An overview of the experiments, absorption analysis and numerical simulation is presented and discussed.

scholarly journals Transit-period search from single-event space-based data: the role of wide-field surveys

2019 ◽  
Vol 625 ◽  
pp. A145
Author(s):  
Geza Kovacs
Keyword(s):  
High Precision ◽  
Wide Field ◽  
Precision Data ◽  
Frequency Spectra ◽  
Transiting Planets ◽  
High Precision Data ◽  
Space Data ◽  
Signal Search

We investigate the optimization of dataset weighting in searching for the orbital period of transiting planets when high-precision space-based data with a single transit event are combined with (relatively) low-precision ground-based (wide-field) data. The optimization stems from the lack of multiple events in the high-precision data and the likely presence of such events in the low-precision data. With noise minimization, we combined two types of frequency spectra: (i) spectra that use two fixed transit parameters (moment of the center of the transit and duration of the event) derived from the space data alone; (ii) spectra that result from the traditional weighted box signal search with optimized transit parameters for each trial period. We used many mock signals to test the detection power of the method. Marginal or no detections in the ground-based data may lead to secure detections in the combined data with the above weighting. Depending on the coverage and quality of the ground-based data, transit depths of ~0.05% and periods up to ~100 days are accessible by the suggested optimum combination of the data.

Development of Calibration Equipment for Geodetic Angle Measurement Instruments

2015 ◽  
Vol 220-221 ◽  
pp. 396-400
Author(s):  
Lauryna Šiaudinytė ◽  
Deividas Sabaitis ◽  
Domantas Bručas ◽  
Gintaras Dmitrijev
Keyword(s):  
Low Cost ◽  
Cost Effective ◽  
Angle Measurement ◽  
Measurement Instruments ◽  
Measurement Systems ◽  
Complex Processes ◽  
Cost Effective Alternative ◽  
Reducing Costs ◽  
The Cost

Production of high precision circular scales is a complicated process requiring expensive equipment and complex processes to achieve. Precision angle measurement equipment tends to be very expensive and therefore not accessible to all in need. Simplification of production of such devices can lead to reducing costs of angle measurement systems ensuring easier accessibility. A new method of producing precision circular scales using low cost mass production can reduce the costs of these devices drastically. Therefore, utilising a common CD technology as the basis for such scales is analysed. This paper deals with the analysis of the newest laser cutting method for plastic circular scales. Preliminary results of manufacturing such scales are presented in the paper as well as measurements of the grating of the scale were performed. The quality of different scales manufactured using different laser types is analysed in the study. The cost – effective alternative of manufacturing circular scales is discussed in the paper.

scholarly journals A systematic review of objective burn scar measurements

2016 ◽  
Vol 4 ◽  
pp. 1-33 ◽  
Author(s):  
Kwang Chear Lee ◽  
Janine Dretzke ◽  
Liam Grover ◽  
Ann Logan ◽  
Naiem Moiemen
Keyword(s):  
Biomechanical Properties ◽  
Ease Of Use ◽  
High Frequency Ultrasound ◽  
Burn Scar ◽  
Measurement Systems ◽  
Measurement Tools ◽  
Measurement Devices ◽  
Frequency Ultrasound ◽  
Area And Volume

Abstract Background Problematic scarring remains a challenging aspect to address in the treatment of burns and can significantly affect the quality of life of the burn survivor. At present, there are few treatments available in the clinic to control adverse scarring, but experimental pharmacological anti-scarring strategies are now beginning to emerge. Their comparative success must be based on objective measurements of scarring, yet currently the clinical assessment of scars is not carried out systematically and is mostly based on subjective review of patients. However, several techniques and devices are being introduced that allow objective analysis of the burn scar. The aim of this article is to evaluate various objective measurement tools currently available and recommend a useful panel that is suitable for use in clinical trials of anti-scarring therapies. Methods A systematic literature search was done using the Web of Science, PubMed and Cochrane databases. The identified devices were then classified and grouped according to the parameters they measured. The tools were then compared and assessed in terms of inter- and intra-rater reproducibility, ease of use and cost. Results After duplicates were removed, 5062 articles were obtained in the search. After further screening, 157 articles which utilised objective burn scar measurement systems or tools were obtained. The scar measurement devices can be broadly classified into those measuring colour, metric variables, texture, biomechanical properties and pathophysiological disturbances. Conclusions Objective scar measurement tools allow the accurate and reproducible evaluation of scars, which is important for both clinical and scientific use. However, studies to evaluate their relative performance and merits of these tools are scarce, and there remain factors, such as itch and pain, which cannot be measured objectively. On reviewing the available evidence, a panel of devices for objective scar measurement is recommended consisting of the 3D cameras (Eykona/Lifeviz/Vectra H1) for surface area and volume, DSM II colorimeter for colour, Dermascan high-frequency ultrasound for scar thickness and Cutometer for skin elasticity and pliability.

scholarly journals A Multisensor Comparison of Ocean Wave Frequency Spectra from a Research Vessel during the Southern Ocean Gas Exchange Experiment

2013 ◽  
Vol 30 (12) ◽  
pp. 2907-2925 ◽  
Author(s):  
Alejandro Cifuentes-Lorenzen ◽  
James B. Edson ◽  
Christopher J. Zappa ◽  
Ludovic Bariteau
Keyword(s):  
High Frequency ◽  
Doppler Radar ◽  
Inertial Sensors ◽  
Wave Spectrum ◽  
Ocean Wave ◽  
Modulation Transfer ◽  
Laser Altimeter ◽  
Frequency Spectra ◽  
Wave Statistics ◽  
Wave Measurements

Abstract Obtaining accurate measurements of wave statistics from research vessels remains a challenge due to the platform motion. One principal correction is the removal of ship heave and Doppler effects from point measurements. Here, open-ocean wave measurements were collected using a laser altimeter, a Doppler radar microwave sensor, a radar-based system, and inertial measurement units. Multiple instruments were deployed to capture the low- and high-frequency sea surface displacements. Doppler and motion correction algorithms were applied to obtain a full 1D (0.035–1.3 ± 0.2 Hz) wave spectrum. The radar-based system combined with the laser altimeter provided the optimal low- and high-frequency combination, producing a frequency spectrum in the range from 0.035 to 1.2 Hz for cruising speeds ≤3 m s−1 with a spectral rolloff of f−4 Hz and noise floor of −20/−30 dB. While on station, the significant wave height estimates were comparable within 10%–15% among instrumentation. Discrepancies in the total energy and in the spectral shape between instruments arise when the ship is in motion. These differences can be quantified using the spectral behavior of the measurements, accounting for aliasing and Doppler corrections. The inertial sensors provided information on the amplitude of the ship’s modulation transfer function, which was estimated to be ~1.3 ± 0.2 while on station and increased while underway [2.1 at ship-over-ground (SOG) speed; 4.3 m s−1]. The correction scheme presented here is adequate for measurements collected at cruising speeds of 3 m s−1 or less. At speeds greater than 5 m s−1, the motion and Doppler corrections are not sufficient to correct the observed spectral degradation.

Sign in / Sign up

Export Citation Format

Share Document