scholarly journals EARLINET instrument intercomparison campaigns: overview on strategy and results

2016 ◽  
Vol 9 (3) ◽  
pp. 1001-1023 ◽  
Author(s):  
Ulla Wandinger ◽  
Volker Freudenthaler ◽  
Holger Baars ◽  
Aldo Amodeo ◽  
Ronny Engelmann ◽  
...  
Keyword(s):  
Reference Systems ◽  
Comprehensive Strategy ◽  
Individual Measurement ◽  
Extinction Coefficients ◽  
Depth Analysis ◽  
Measurement Channels ◽  
Instrument Intercomparison ◽  
Technical Solutions ◽  
Instrument Level ◽  
Good Agreement

Abstract. This paper introduces the recent European Aerosol Research Lidar Network (EARLINET) quality-assurance efforts at instrument level. Within two dedicated campaigns and five single-site intercomparison activities, 21 EARLINET systems from 18 EARLINET stations were intercompared between 2009 and 2013. A comprehensive strategy for campaign setup and data evaluation has been established. Eleven systems from nine EARLINET stations participated in the EARLINET Lidar Intercomparison 2009 (EARLI09). In this campaign, three reference systems were qualified which served as traveling standards thereafter. EARLINET systems from nine other stations have been compared against these reference systems since 2009. We present and discuss comparisons at signal and at product level from all campaigns for more than 100 individual measurement channels at the wavelengths of 355, 387, 532, and 607 nm. It is shown that in most cases, a very good agreement of the compared systems with the respective reference is obtained. Mean signal deviations in predefined height ranges are typically below ±2 %. Particle backscatter and extinction coefficients agree within ±2  ×  10−4 km−1 sr−1 and ± 0.01 km−1, respectively, in most cases. For systems or channels that showed larger discrepancies, an in-depth analysis of deficiencies was performed and technical solutions and upgrades were proposed and realized. The intercomparisons have reinforced confidence in the EARLINET data quality and allowed us to draw conclusions on necessary system improvements for some instruments and to identify major challenges that need to be tackled in the future.

scholarly journals EARLINET instrument intercomparison campaigns: overview on strategy and results

2015 ◽  
Vol 8 (10) ◽  
pp. 10473-10522 ◽  
Author(s):  
U. Wandinger ◽  
V. Freudenthaler ◽  
H. Baars ◽  
A. Amodeo ◽  
R. Engelmann ◽  
...  
Keyword(s):  
Reference Systems ◽  
Comprehensive Strategy ◽  
Individual Measurement ◽  
Extinction Coefficients ◽  
Depth Analysis ◽  
Measurement Channels ◽  
Instrument Intercomparison ◽  
Technical Solutions ◽  
Instrument Level ◽  
Good Agreement

Abstract. This paper introduces the recent EARLINET quality-assurance efforts at instrument level. Within two dedicated campaigns and five single-site intercomparison activities 21 EARLINET systems from 18 EARLINET stations were intercompared between 2009 and 2013. A comprehensive strategy for campaign setup and data evaluation has been established. Eleven systems from nine EARLINET stations participated in the EARLINET Lidar Intercomparison 2009 (EARLI09). In this campaign, three reference systems were qualified which served as traveling standards thereafter. EARLINET systems from nine other stations have been compared against these reference systems since 2009. We present and discuss comparisons at signal and at product level from all campaigns for more than 100 individual measurement channels at the wavelengths of 355, 387, 532 and 607 nm. It is shown that in most cases a very good agreement of the compared systems with the respective reference is obtained. Mean signal deviations in pre-defined height ranges are typically below ±2 %. Particle backscatter and extinction coefficients agree within ±2 × 10−4 km−1 sr−1 and ± 0.01 km−1, respectively, in most cases. For systems or channels that showed larger discrepancies, an in-depth analysis of deficiences was performed and technical solutions and upgrades were proposed and realized. The intercomparisons have reinforced the confidence in the EARLINET data quality and allowed us to draw conclusions on necessary system improvements for some instruments and to identify major challenges that need to be tackled in the future.

scholarly journals Proper Motions of the Clouds

1999 ◽  
Vol 190 ◽  
pp. 475-479 ◽  
Author(s):  
Claudio Anguita
Keyword(s):  
Proper Motion ◽  
Reference Systems ◽  
Proper Motions ◽  
Magellanic Stream ◽  
Good Agreement

The proper motion of the LMC relative to three background QSOs has been determined. 125 CCD frames taken from 1989.0 to 1997.2 at the Cassegrain focus of the CTIO 1.5 m telescope were used. The method of observation and reduction is breafly presented. The results are compared with those obtained by other authors who use different methods and proper motion reference systems. We find a good agreement in μαcosδ, but a rather large discrepancy in μδ. Our LMC proper motion seems to indicate that the LMC is not leading the Magellanic Stream.

Nanofluid Extinction Coefficients for Photothermal Energy Conversion

2011 ◽  
Author(s):  
Robert A. Taylor ◽  
Patrick E. Phelan ◽  
Ronald Adrian ◽  
Ravi Prasher ◽  
Todd P. Otanicar
Keyword(s):  
Bulk Properties ◽  
Extinction Coefficients ◽  
Energy Harvesters ◽  
Nanoparticle Suspensions ◽  
Model Predictions ◽  
Testing Data ◽  
Simplifying Assumptions ◽  
Solar Thermal Collectors ◽  
Base Liquid ◽  
Good Agreement

Suspensions of nanoparticles in liquids (i.e. nanofluids) have been shown to dramatically affect thermal and optical properties of the base liquid at low particle loadings [1–3]. Recent studies by the co-authors have indicated that selected nanofluids are promising as solar energy harvesters [4,5]. In order to determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, the extinction coefficient of real nanofluids must be established. Although it is relatively straight-forward to model these properties from knowledge of bulk properties, with the help of some simplifying assumptions, real spectroscopy tests do not always match these calculations. This study compares model predictions of extinction coefficients to spectroscopic measurements. Unfortunately, the models and the optical testing data do not show very good agreement. Some possible reasons for this are discussed. Also, some simple experiments are presented to investigate the extent of scattering in nanoparticle suspensions. As alluded to above, all of these tests are conducted on nanofluid compositions which are considered to be suitable for solar thermal collectors.

scholarly journals Torque Characteristics of the Revolving Vane Air Expander

Machines ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 58
Author(s):  
Kuan Thai Aw ◽  
Alison Subiantoro ◽  
Kim Tiow Ooi
Keyword(s):  
High Efficiency ◽  
Clean Energy ◽  
Compressed Air ◽  
Generic Model ◽  
Alternative Source ◽  
Output Torque ◽  
Depth Analysis ◽  
Rotary Machines ◽  
Rotational Vibration ◽  
Good Agreement

The use of compressed air as an alternative source of clean energy requires an air expander to extract work. A new design, known as the revolving vane mechanism, has been proposed in an effort to develop high efficiency rotary machines. This paper provides an in-depth analysis by including the vibration characteristics of the revolving vane air expander to evaluate the steady-state operating output torque. A generic model for describing the revolving vane rotational vibration is first derived and subsequently modified to describe the prototype tested. Measurements show that the output torque is bimodal; arising from a tolerance gap between the vane and its slot during fabrication. This effect was found to be less pronounced at high operating speeds. The model is found to be in good agreement with the measured output torques. Further analysis with the validated model showed that extracting shaft work from the cylinder would result in better performance.

scholarly journals Estimated desert-dust ice nuclei profiles from polarization lidar: methodology and case studies

2015 ◽  
Vol 15 (6) ◽  
pp. 3463-3477 ◽  
Author(s):  
R. E. Mamouri ◽  
A. Ansmann
Keyword(s):  
Orthogonal Polarization ◽  
Data Sets ◽  
Retrieval Method ◽  
Extinction Coefficients ◽  
Desert Dust ◽  
Ice Nuclei ◽  
University Of Technology ◽  
Close Relationship ◽  
Lidar Observations ◽  
Good Agreement

Abstract. A lidar method is presented that permits the estimation of height profiles of ice nuclei concentrations (INC) in desert dust layers. The polarization lidar technique is applied to separate dust and non-dust backscatter and extinction coefficients. The desert dust extinction coefficients σd are then converted to aerosol particle number concentrations APC280 which consider particles with radius > 280 nm only. By using profiles of APC280 and ambient temperature T along the laser beam, the profile of INC can be estimated within a factor of 3 by means of APC-T-INC parameterizations from the literature. The observed close relationship between σd at 500 nm and APC280 is of key importance for a successful INC retrieval. We studied this link by means of AERONET (Aerosol Robotic Network) sun/sky photometer observations at Morocco, Cabo Verde, Barbados, and Cyprus during desert dust outbreaks. The new INC retrieval method is applied to lidar observations of dust layers with the spaceborne lidar CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) during two overpasses over the EARLINET (European Aerosol Research Lidar Network) lidar site of the Cyprus University of Technology (CUT), Limassol (34.7° N, 33° E), Cyprus. The good agreement between the CALIOP and CUT lidar retrievals of σd, APC280, and INC profiles corroborates the potential of CALIOP to provide 3-D global desert dust APC280 and INC data sets.

Combined Experimental-Numerical Approach to Determine Radiation Properties of Particle Suspensions

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Jan Marti ◽  
Matthew Roesle ◽  
Aldo Steinfeld
Keyword(s):  
Numerical Approach ◽  
Particle Suspensions ◽  
Participating Media ◽  
Extinction Coefficients ◽  
Radiation Properties ◽  
Radiation Distribution ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Good Agreement ◽  
Sic Particle

A combination of experimental measurements with a numerical model is used to find the volume-averaged radiation properties—extinction coefficient, scattering albedo and approximated scattering phase function—of SiC particle suspensions with varying particle loadings. The experimentally determined angular radiation distribution of irradiated SiC samples is applied to fit a collision-based Monte Carlo (MC) model with a continuous participating media defining the particle suspension. A validation case with glass microspheres and Mie theory is implemented to verify the modeling procedure. Two types of SiC particles with dissimilar optical characteristics are examined and the respective radiation properties are determined for particle loadings between 0.05 and 0.30. The extinction coefficients of both types of SiC particle are in good agreement with the dependent scattering correlation of Kaviany and Singh.

scholarly journals Experimental and numerical investigation of thermal and flow conditions inside a large pharmaceutical storage after the ventilation system failure

2021 ◽  
pp. 346-346
Author(s):  
Ilija Tabasevic ◽  
Rastko Jovanovic ◽  
Dragan Milanovic
Keyword(s):  
Temperature Distribution ◽  
Flow Field ◽  
Flow Rate ◽  
Ventilation System ◽  
Pharmaceutical Products ◽  
System Failure ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Depth Analysis ◽  
Good Agreement

Safe storage of pharmaceutical products is of great importance due to potential hazards for human health. The aim of this study was to assess the ability of pharmaceutical storage to recover design temperature during ventilation system recovery. The performed CFD simulations showed good agreement with experimental temperature measurements. Numerical results allowed in-depth analysis of flow field and temperature distribution inside the storage. It was discovered that the flow field is highly non-uniform, which consequently leads to an uneven temperature distribution of pallets with products. However, a high inlet mass flow rate ensured that all pallets reach the designed temperature.

scholarly journals The subgiant HR 7322 as an asteroseismic benchmark star

2019 ◽  
Vol 489 (1) ◽  
pp. 928-940 ◽  
Author(s):  
Amalie Stokholm ◽  
Poul Erik Nissen ◽  
Víctor Silva Aguirre ◽  
Timothy R White ◽  
Mikkel N Lund ◽  
...  
Keyword(s):  
Oscillation Mode ◽  
Stellar Radius ◽  
Avoided Crossing ◽  
Depth Analysis ◽  
Fitting Algorithm ◽  
Dipole Oscillation ◽  
Standard Models ◽  
Oscillation Frequencies ◽  
Gaia Dr2 ◽  
Good Agreement

Abstract We present an in-depth analysis of the bright subgiant HR 7322 (KIC 10005473) using Kepler short-cadence photometry, optical interferometry from CHARA, high-resolution spectra from SONG, and stellar modelling using garstec grids, and the Bayesian grid-fitting algorithm basta. HR 7322 is only the second subgiant with high-quality Kepler asteroseismology for which we also have interferometric data. We find a limb-darkened angular diameter of 0.443 ± 0.007 mas, which, combined with a distance derived using the parallax from Gaia DR2 and a bolometric flux, yields a linear radius of 2.00 ± 0.03 R⊙ and an effective temperature of 6350 ± 90 K. HR 7322 exhibits solar-like oscillations, and using the asteroseismic scaling relations and revisions thereof, we find good agreement between asteroseismic and interferometric stellar radius. The level of precision reached by the careful modelling is to a great extent due to the presence of an avoided crossing in the dipole oscillation mode pattern of HR 7322. We find that the standard models predict a stellar radius systematically smaller than the observed interferometric one and that a sub-solar mixing length parameter is needed to achieve a good fit to individual oscillation frequencies, interferometric temperature, and spectroscopic metallicity.

Preliminary Design and Performance Estimation of Radial Inflow Turbines: An Automated Approach

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Carlos A.M. Ventura ◽  
Peter A. Jacobs ◽  
Andrew S. Rowlands ◽  
Paul Petrie-Repar ◽  
Emilie Sauret
Keyword(s):  
Search Algorithm ◽  
Three Dimensional ◽  
Thermodynamic Cycle ◽  
Search Space ◽  
Performance Estimation ◽  
Preliminary Design ◽  
Novel Approach ◽  
Depth Analysis ◽  
And Performance ◽  
Good Agreement

A comprehensive one-dimensional meanline design approach for radial inflow turbines is described in the present work. An original code was developed in Python that takes a novel approach to the automatic selection of feasible machines based on pre-defined performance or geometry characteristics for a given application. It comprises a brute-force search algorithm that traverses the entire search space based on key non-dimensional parameters and rotational speed. In this study, an in-depth analysis and subsequent implementation of relevant loss models as well as selection criteria for radial inflow turbines is addressed. Comparison with previously published designs, as well as other available codes, showed good agreement. Sample (real and theoretical) test cases were trialed and results showed good agreement when compared to other available codes. The presented approach was found to be valid and the model was found to be a useful tool with regards to the preliminary design and performance estimation of radial inflow turbines, enabling its integration with other thermodynamic cycle analysis and three-dimensional blade design codes.

scholarly journals Automatic Lidar Calibration and Processing Program for Multiwavelength Raman Polarization Lidar

2020 ◽  
Vol 237 ◽  
pp. 08007
Author(s):  
Zhenping Yin ◽  
Holger Baars ◽  
Patric Seifert ◽  
Ronny Engelmann
Keyword(s):  
Water Vapor ◽  
Mixing Ratio ◽  
Extinction Coefficients ◽  
Good Consistency ◽  
Processing Program ◽  
Lidar Ratio ◽  
Water Vapor Mixing Ratio ◽  
Lidar Calibration ◽  
Aerosol Backscatter ◽  
Good Agreement

A new version of automatic lidar calibration and processing program was developed to process the data from multiwavelength Raman polarization lidar. The absolute lidar calibration and water vapor calibration algorithms were applied. The program can provide plentiful products, like aerosol backscatter and extinction coefficients, lidar ratio, Ångström exponent, volume and particle depolarization ratios, water vapor mixing ratio and aerosol target classification. Good agreement was found in the comparison with manual quality-assured profiles or radiosonde measurement. Lidar calibration based on the aerosol optical properties retrieved with Raman method, Klett method and AOD-Constrained method were implemented. Good consistency was found.

Sign in / Sign up

Export Citation Format

Share Document