scholarly journals Night-sky imaging as a potential tool for characterization of total lumen output from small and medium-sized cities

2020 ◽  
Vol 494 (4) ◽  
pp. 5008-5017
Author(s):  
S Wallner ◽  
M Kocifaj ◽  
L Komar ◽  
H A Solano-Lamphar
Keyword(s):  
Satellite Data ◽  
Light Emitting ◽  
Large Cities ◽  
Major Interest ◽  
Night Sky ◽  
Lighting Systems ◽  
The Impact

ABSTRACT In this article, the asymptotic formula developed in past work and applied to predict skyglow due to distant sources was evolved, with the objective of characterizing small and medium-sized cities in the observer's surroundings. To enable this, a combination of theoretical computations and in situ measurements is needed, aiming to distinguish between dominant and smaller light-emitting sources, with the latter usually being camouflaged when measuring the night sky. Furthermore, for numerical modelling of skyglow, few of the most important parameters, specifically the amount of total lumens installed and radiated to the upward hemisphere, can be derived. Astronomical observatories, in particular, can profit from this concept, since they are usually situated far away from large cities but can still be surrounded by smaller villages and towns. We present a detailed description of how theoretical computations are combined with all-sky photometry in order to obtain the properties mentioned. Results are compared with satellite data, showing that, regarding approximations undertaken for processing, they are comparable, underlining the functionality of our approach. The idea of including in situ observations enables us to quantify the impact of small and medium-sized cities globally and independent of location, as long as measurements were conducted outside light domes. In addition, the presented work may be of major interest to the light-pollution community if conducting long-term observations of cities, since the quality of commonly used satellite data is going to decrease in the future, due to blindness in short wavelengths and upcoming conversions of public lighting systems to blue-enlightened LEDs.

Operating Temperature Analysis of LED with Cylindrical Cu Slug

2014 ◽  
Vol 487 ◽  
pp. 145-148 ◽  
Author(s):  
Rajendaran Vairavan ◽  
Zaliman Sauli ◽  
Vithyacharan Retnasamy
Keyword(s):  
Natural Convection ◽  
Operating Temperature ◽  
Simulation Method ◽  
Input Power ◽  
Junction Temperature ◽  
Temperature Analysis ◽  
Light Emitting ◽  
New Era ◽  
Lighting Systems

High power light emitting diodes is the new era of lighting due to momentous supremacy in terms of lighting efficacy over traditional lighting systems. The reliability of LED is dependent on its junction temperature. This study confers on the thermal and stress characterization of LED chip with copper cylindrical heat slug through simulation method. The simulation characterization was carried out with Ansys version 11 at ambient temperature of 25°C under natural convection condition. The LED package was powered with input powers of 0.1 W, 0.5 W and 1W .Results indicated that input power influences the junction temperature and stress of LED chip.

Assessing the impact of the transition to Light Emitting Diodes based solar lighting systems in India

2013 ◽  
Vol 17 (4) ◽  
pp. 363-370 ◽  
Author(s):  
Santosh M. Harish ◽  
Shuba V. Raghavan ◽  
Milind Kandlikar ◽  
Gireesh Shrimali
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
Solar Lighting ◽  
Lighting Systems ◽  
The Impact

Design, Measurements and Characterization of Smart Electronic Board for PV Streetlight based on LED and High Intensity Discharge Lamps

2013 ◽  
pp. 153-165
Author(s):  
Paolo Visconti ◽  
Daniele Romanello ◽  
Giovanni Zizzari ◽  
Vito Ventura ◽  
Giorgio Cavalera
Keyword(s):  
Rural Areas ◽  
High Intensity ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Electronic Board ◽  
Lighting Systems ◽  
And Control ◽  
Near Future ◽  
Hid Lamps

This work presents an electronic board for driving and control of High Intensity Discharge (HID) lamps and Light Emitting Diode (LED) lamps. The proposed electronic board is able to drive HID or LED lamps by means of a reconfigurable output. This feature allows using the ballast in lighting systems that currently use traditional discharge lamps, as well as keeping the same ballast when discharge lamps are replaced by LED modules in the near future, when LED street lighting systems will be more affordable. Additionally, since the lighting system is designed to be used in rural areas where there is no public electricity, each lighting point incorporates a system to convert solar energy into continuous voltage by means of photovoltaic panels. In this work, energy saving issues are taken into account.

scholarly journals The use of QBO, ENSO, and NAO perturbations in the evaluation of GOME-2 MetOp A total ozone measurements

2019 ◽  
Vol 12 (2) ◽  
pp. 987-1011
Author(s):  
Kostas Eleftheratos ◽  
Christos S. Zerefos ◽  
Dimitris S. Balis ◽  
Maria-Elissavet Koukouli ◽  
John Kapsomenakis ◽  
...  
Keyword(s):  
Satellite Data ◽  
Total Ozone ◽  
Southern Oscillation ◽  
Model Calculations ◽  
Ozone Data ◽  
Ozone Monitoring ◽  
Mean Differences ◽  
The Tropics ◽  
The Impact

Abstract. In this work we present evidence that quasi-cyclical perturbations in total ozone (quasi-biennial oscillation – QBO, El Niño–Southern Oscillation – ENSO, and North Atlantic Oscillation – NAO) can be used as independent proxies in evaluating Global Ozone Monitoring Experiment (GOME) 2 aboard MetOp A (GOME-2A) satellite total ozone data, using ground-based (GB) measurements, other satellite data, and chemical transport model calculations. The analysis is performed in the frame of the validation strategy on longer time scales within the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility on Atmospheric Composition Monitoring (AC SAF) project, covering the period 2007–2016. Comparison of GOME-2A total ozone with ground observations shows mean differences of about -0.7±1.4 % in the tropics (0–30∘), about +0.1±2.1 % in the mid-latitudes (30–60∘), and about +2.5±3.2 % and 0.0±4.3 % over the northern and southern high latitudes (60–80∘), respectively. In general, we find that GOME-2A total ozone data depict the QBO–ENSO–NAO natural fluctuations in concurrence with the co-located solar backscatter ultraviolet radiometer (SBUV), GOME-type Total Ozone Essential Climate Variable (GTO-ECV; composed of total ozone observations from GOME, SCIAMACHY – SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY, GOME-2A, and OMI – ozone monitoring instrument, combined into one homogeneous time series), and ground-based observations. Total ozone from GOME-2A is well correlated with the QBO (highest correlation in the tropics of +0.8) in agreement with SBUV, GTO-ECV, and GB data which also give the highest correlation in the tropics. The differences between deseazonalized GOME-2A and GB total ozone in the tropics are within ±1 %. These differences were tested further as to their correlations with the QBO. The differences had practically no QBO signal, providing an independent test of the stability of the long-term variability of the satellite data. Correlations between GOME-2A total ozone and the Southern Oscillation Index (SOI) were studied over the tropical Pacific Ocean after removing seasonal, QBO, and solar-cycle-related variability. Correlations between ozone and the SOI are on the order of +0.5, consistent with SBUV and GB observations. Differences between GOME-2A and GB measurements at the station of Samoa (American Samoa; 14.25∘ S, 170.6∘ W) are within ±1.9 %. We also studied the impact of the NAO on total ozone in the northern mid-latitudes in winter. We find very good agreement between GOME-2A and GB observations over Canada and Europe as to their NAO-related variability, with mean differences reaching the ±1 % levels. The agreement and small differences which were found between the independently produced total ozone datasets as to the influence of the QBO, ENSO, and NAO show the importance of these climatological proxies as additional tool for monitoring the long-term stability of satellite–ground-truth biases.

The Use of Laboratory-Measured and Strain-Gauge Backcalculated Asphalt Stiffness for Rutting Performance Prediction

2019 ◽  
Vol 2673 (3) ◽  
pp. 323-333
Author(s):  
Erdem Coleri ◽  
John T. Harvey
Keyword(s):  
Performance Prediction ◽  
Strain Gauge ◽  
Asphalt Concrete ◽  
Laboratory Tests ◽  
Concrete Materials ◽  
Long Term Performance ◽  
Term Performance ◽  
The Impact

Laboratory tests are conducted with asphalt concrete materials to determine the expected in-situ performance. In addition, laboratory test results are commonly used in mechanistic-empirical design methods for material characterization to improve the predictive accuracy of the models. However, the effectiveness of laboratory tests in characterizing the long-term performance of asphalt concrete materials needs to be validated to be able to use the results for pavement design and long-term performance prediction. Inaccurate performance characterization and prediction can directly affect the decision-making process for pavement maintenance, rehabilitation, and reconstruction and result in unexpected early failures in the field. The major objective of this study is to determine the impact of using laboratory-measured asphalt stiffness on the prediction accuracy of mechanistic-empirical models. In addition, the effect of using linear-elastic modeling assumptions (layered elastic theory) and neglecting the nonlinearity of pavement response at high load levels (and/or at high strain levels for weaker structures) on the predicted rutting performance was determined. In this study, the effectiveness of the use of laboratory asphalt stiffness tests for in-situ asphalt stiffness characterization was determined by comparing the rutting performance predicted using laboratory-measured stiffness to rutting predicted using strain-gauge backcalculated stiffness. It was determined that laboratory tests are able to characterize the in-situ stiffness characteristics of the asphalt mix used in this study and the stiffness characterization process suggested in this study can provide reliable rutting performance predictions. Results of this study are only applicable to tested rubberized asphalt concrete mixtures.

Belastung von Patienten und Gesundheitssystem durch Pleuraverweildrainage zur Versorgung chronischer Pleuraergüsse

2019 ◽  
Vol 7 (2) ◽  
pp. 84-85
Author(s):  
Axel Tobias Kempa
Keyword(s):  
Length Of Hospital Stay ◽  
Chest Drain ◽  
Long Term Outcomes ◽  
Talc Pleurodesis ◽  
In Situ Methods ◽  
Hospital Visits ◽  
The Impact

Background: Indwelling pleural catheters (IPC) offer an alternative to talc pleurodesis in recurrent effusion, especially in patients wishing to avoid hospitalization. Two randomized trials have demonstrated reduced time in hospital using IPCs versus talc pleurodesis in malignant pleural effusion (MPE). However, the impact of IPCs on hospital services and patients has not been well studied. Objectives: To analyze long-term outcomes of IPCs and understand the hospital burden in terms of requirement for hospital visits and contacts with healthcare, while the IPC was in situ. Methods: IPC insertions in a tertiary pleural center were analyzed retrospectively. Reviews of patients with IPCs in situ considered «additional» to routine clinical follow-up were defined pre-hoc. Results: A total of 202 cases were analyzed: 89.6% MPE group (n = 181) and 10.4% non-MPE group (n = 21). There were a median 3.0 (interquartile range [IQR] 3) and 2.0 (IQR 2) ipsilateral pleural procedures prior to each IPC insertion in non-MPE and MPE groups, respectively (p = 0.26), and a mean 1.3 (SD 1.7) planned IPC-related outpatient follow-up visits per patient. There were 2 (9.5%) and 14 (7.7%) IPC-related infections in non-MPE and MPE groups, respectively. Four (19.0%) and 44 (24.3%) patients required additional IPC-related reviews in non-MPE and MPE groups, respectively (p = 0.6), and these occurred within 250 days post IPC insertion. Conclusions: Although IPCs decrease initial length of hospital stay compared to talc pleurodesis via chest drain, IPCs are associated with significant hospital-visit burden, in addition to planned visits and regular home IPC drainages. IPC-using services need to be prepared for this additional work to run an IPC service effectively.

Towards a long term global snow climate data record from satellite data generated within the Snow Climate Change Initiative

2020 ◽  
Author(s):  
Gabriele Schwaizer ◽  
Lars Keuris ◽  
Thomas Nagler ◽  
Chris Derksen ◽  
Kari Luojus ◽  
...  
Keyword(s):  
Time Series ◽  
Satellite Data ◽  
Snow Water Equivalent ◽  
Climate Model ◽  
Process Models ◽  
Climate Data ◽  
Seasonal Snow ◽  
Snow Water

<p>Seasonal snow is an important component of the global climate system. It is highly variable in space and time and sensitive to short term synoptic scale processes and long term climate-induced changes of temperature and precipitation. Current snow products derived from various satellite data applying different algorithms show significant discrepancies in extent and snow mass, a potential source for biases in climate monitoring and modelling. The recently launched ESA CCI+ Programme addresses seasonal snow as one of 9 Essential Climate Variables to be derived from satellite data.</p><p>In the snow_cci project, scheduled for 2018 to 2021 in its first phase, reliable fully validated processing lines are developed and implemented. These tools are used to generate homogeneous multi-sensor time series for the main parameters of global snow cover focusing on snow extent and snow water equivalent. Using GCOS guidelines, the requirements for these parameters are assessed and consolidated using the outcome of workshops and questionnaires addressing users dealing with different climate applications. Snow extent product generation applies algorithms accounting for fractional snow extent and cloud screening in order to generate consistent daily products for snow on the surface (viewable snow) and snow on the surface corrected for forest masking (snow on ground) with global coverage. Input data are medium resolution optical satellite images (AVHRR-2/3, AATSR, MODIS, VIIRS, SLSTR/OLCI) from 1981 to present. An iterative development cycle is applied including homogenisation of the snow extent products from different sensors by minimizing the bias. Independent validation of the snow products is performed for different seasons and climate zones around the globe from 1985 onwards, using as reference high resolution snow maps from Landsat and Sentinel- 2as well as in-situ snow data following standardized validation protocols.</p><p>Global time series of daily snow water equivalent (SWE) products are generated from passive microwave data from SMMR, SSM/I, and AMSR from 1978 onwards, combined with in-situ snow depth measurements. Long-term stability and quality of the product is assessed using independent snow survey data and by intercomparison with the snow information from global land process models.</p><p>The usability of the snow_cci products is ensured through the Climate Research Group, which performs case studies related to long term trends of seasonal snow, performs evaluations of CMIP-6 and other snow-focused climate model experiments, and applies the data for simulation of Arctic hydrological regimes.</p><p>In this presentation, we summarize the requirements and product specifications for the snow extent and SWE products, with a focus on climate applications. We present an overview of the algorithms and systems for generation of the time series. The 40 years (from 1980 onwards) time series of daily fractional snow extent products from AVHRR with 5 km pixel spacing, and the 20-year time series from MODIS (1 km pixel spacing) as well as the coarse resolution (25 km pixel spacing) of daily SWE products from 1978 onwards will be presented along with first results of the multi-sensor consistency checks and validation activities.</p>

Sign in / Sign up

Export Citation Format

Share Document