Technical Note: Airborne Sound Insulation of Hollow Brickwork

2007 ◽  
Vol 14 (3) ◽  
pp. 231-239 ◽  
Author(s):  
Jesús Alba ◽  
Jaime Ramis ◽  
Eva Escuder ◽  
Laura Berto
Keyword(s):  
Standard Deviation ◽  
Technical Note ◽  
In Situ Measurements ◽  
Sound Insulation ◽  
Expansion Joints ◽  
Airborne Sound ◽  
Hollow Brick ◽  
Multiple Measurements ◽  
The Mean

This paper reports on the uncertainty of in situ measurements of the airborne sound insulation of hollow-brick walls in different housing plans, with emphasis on the influence of expansion joints. The mean and standard deviation of multiple measurements are obtained, which show significant differences in insulation values despite the fact that the same construction was used in each case.

scholarly journals AIRBORNE SOUND INSULATION IMPROVEMENT ON MASONRY PARTITIONS USING ADDITIONAL PLASTERBOARD LAYERS

2011 ◽  
Vol 3 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Marius Mickaitis ◽  
Aleksandras Jagniatinskis ◽  
Boris Fiks
Keyword(s):  
Theoretical Calculations ◽  
Low Frequency ◽  
Masonry Wall ◽  
In Situ Measurements ◽  
Sound Insulation ◽  
Frequency Range ◽  
Airborne Sound ◽  
Sound Reduction ◽  
Reduction Index

For the purposes of accumulating knowledge of how to comply with requirements for new buildings of obligatory sound class C or enhanced acoustic comfort sound classes A and B (Lithuanian Building Technical regulations STR 2.01.07:2003), the article discusses improvement on airborne sound insulation of partitions between dwellings using additional plasterboard layers. The results of an empirical approach were obtained performing in situ measurements of the partitions of masonry from silicate blocks and expanded-clay concrete blocks. Theoretical calculations without the evaluation of flanking paths are added. The paper looks at the peculiarities of in situ measurement methods and the estimation of the limiting uncertainty of the sound reduction index. It is showed that the values of the in situ measurements of the airborne sound reduction index in accordance with requirements EN ISO 140 and EN ISO 717 series for rooms having volume higher than 50 m3 varies depending on frequency range. It has been stated, that improvement on the weighed airborne sound reduction index in the frequency range from 100 Hz to 3150 Hz depends on the properties of additional layers and on the characteristics of the main constructions. Resonance in the low frequency range arising due to additional layers may reduce the weighed airborne sound reduction index defined in the frequency range from 50 Hz to 3150 Hz. This fact must be taken into account when designing improvement on masonry wall insulation using an additional layer in dwellings.

scholarly journals Comparison of GOME tropospheric NO<sub>2</sub> columns with NO<sub>2</sub> profiles deduced from ground-based in situ measurements

2006 ◽  
Vol 6 (11) ◽  
pp. 3211-3229 ◽  
Author(s):  
D. Schaub ◽  
K. F. Boersma ◽  
J. W. Kaiser ◽  
A. K. Weiss ◽  
D. Folini ◽  
...  
Keyword(s):  
Standard Deviation ◽  
A Priori ◽  
Relative Difference ◽  
In Situ Measurements ◽  
Data Sets ◽  
Clear Sky ◽  
Tropospheric No2 ◽  
The Mean ◽  
Sky Conditions

Abstract. Nitrogen dioxide (NO2) vertical tropospheric column densities (VTCs) retrieved from the Global Ozone Monitoring Experiment (GOME) are compared to coincident ground-based tropospheric NO2 columns. The ground-based columns are deduced from in situ measurements at different altitudes in the Alps for 1997 to June 2003, yielding a unique long-term comparison of GOME NO2 VTC data retrieved by a collaboration of KNMI (Royal Netherlands Meteorological Institute) and BIRA/IASB (Belgian Institute for Space Aeronomy) with independently derived tropospheric NO2 profiles. A first comparison relates the GOME retrieved tropospheric columns to the tropospheric columns obtained by integrating the ground-based NO2 measurements. For a second comparison, the tropospheric profiles constructed from the ground-based measurements are first multiplied with the averaging kernel (AK) of the GOME retrieval. The second approach makes the comparison independent from the a priori NO2 profile used in the GOME retrieval. This allows splitting the total difference between the column data sets into two contributions: one that is due to differences between the a priori and the ground-based NO2 profile shapes, and another that can be attributed to uncertainties in both the remaining retrieval parameters (such as, e.g., surface albedo or aerosol concentration) and the ground-based in situ NO2 profiles. For anticyclonic clear sky conditions the comparison indicates a good agreement between the columns (n=157, R=0.70/0.74 for the first/second comparison approach, respectively). The mean relative difference (with respect to the ground-based columns) is −7% with a standard deviation of 40% and GOME on average slightly underestimating the ground-based columns. Both data sets show a similar seasonal behaviour with a distinct maximum of spring NO2 VTCs. Further analysis indicates small GOME columns being systematically smaller than the ground-based ones. The influence of different shapes in the a priori and the ground-based NO2 profile is analysed by considering AK information. It is moderate and indicates similar shapes of the profiles for clear sky conditions. Only for large GOME columns, differences between the profile shapes explain the larger part of the relative difference. In contrast, the other error sources give rise to the larger relative differences found towards smaller columns. Further, for the clear sky cases, errors from different sources are found to compensate each other partially. The comparison for cloudy cases indicates a poorer agreement between the columns (n=60, R=0.61). The mean relative difference between the columns is 60% with a standard deviation of 118% and GOME on average overestimating the ground-based columns. The clear improvement after inclusion of AK information (n=60, R=0.87) suggests larger errors in the a priori NO2 profiles under cloudy conditions and demonstrates the importance of using accurate profile information for (partially) clouded scenes.

scholarly journals Comparison of GOME tropospheric NO<sub>2</sub> columns with NO<sub>2</sub> profiles deduced from ground-based in situ measurements

2006 ◽  
Vol 6 (2) ◽  
pp. 2189-2239
Author(s):  
D. Schaub ◽  
K. F. Boersma ◽  
J. W. Kaiser ◽  
A. K. Weiss ◽  
D. Folini ◽  
...  
Keyword(s):  
Standard Deviation ◽  
A Priori ◽  
Relative Difference ◽  
In Situ Measurements ◽  
Data Sets ◽  
Clear Sky ◽  
Tropospheric No2 ◽  
The Mean ◽  
Sky Conditions

Abstract. Nitrogen dioxide (NO2) vertical tropospheric column densities (VTCs) retrieved from the Global Ozone Monitoring Experiment (GOME) are compared to coincident ground-based tropospheric NO2 columns. The ground-based columns are deduced from in situ measurements at different altitudes in the Alps for 1997 to June 2003, yielding a unique long-term comparison of GOME NO2 VTC data retrieved by KNMI/BIRA with independently derived tropospheric NO2 profiles. A first comparison relates the GOME columns to the ground-based NO2 profiles that are directly integrated to tropospheric columns. A second comparison includes averaging kernel (AK) information, which makes the comparison independent from the a priori NO2 profile used in the GOME retrieval. This allows splitting the total difference between the column data sets into two contributions: one that is due to differences between the a priori and the ground-based NO2 profile shapes, and another that can be attributed to uncertainties in both the remaining retrieval parameters and the ground-based in situ NO2 profiles. For anticyclonic clear sky conditions the comparison indicates a good agreement between the columns (n=157, R=0.70/0.74 without/with AK included). Both data sets show a similar seasonal behaviour with a distinct maximum of spring NO2 VTCs. The mean relative difference (with respect to the ground-based columns) is −7% with a standard deviation of 40% and GOME on average slightly underestimating the ground-based columns. Further analysis indicates small GOME columns being systematically smaller than the ground-based ones. The influence of different shapes in the a priori and the ground-based NO2 profile is analysed by considering AK information. It is moderate and indicates similar shapes of the profiles for clear sky conditions. Only for large GOME columns, differences between the profile shapes explain the larger part of the relative difference. In contrast, the other error sources give rise to the larger relative differences found towards smaller columns. Further, for the clear sky cases, errors from different sources are found to compensate each other partially. The comparison for cloudy cases indicates a poorer agreement between the columns (n=60, R=0.61). The mean relative difference between the columns is 60% with a standard deviation of 118% and GOME on average overestimating the ground-based columns. The clear improvement after inclusion of AK information (n=60, R=0.87) suggests larger errors in the a priori NO2 profiles under cloudy conditions and demonstrates the importance of using the kernel information for (partially) clouded scenes.

scholarly journals High-precision quasi-continuous atmospheric greenhouse gas measurements at Trainou tower (Orléans forest, France)

2014 ◽  
Vol 7 (7) ◽  
pp. 2283-2296 ◽  
Author(s):  
M. Schmidt ◽  
M. Lopez ◽  
C. Yver Kwok ◽  
C. Messager ◽  
M. Ramonet ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Atmospheric Measurements ◽  
Flame Ionization ◽  
Gas Detector ◽  
Sampling Height ◽  
The Mean ◽  
Drying System ◽  
Gas Measurements ◽  
Television Tower

Abstract. Results from the Trainou tall tower measurement station installed in 2006 are presented for atmospheric measurements of CO2, CH4, N2O, SF6, CO, H2 mole fractions and radon-222 activity. Air is sampled from four sampling heights (180, 100, 50 and 5 m) of the Trainou 200 m television tower in the Orléans forest in France (47°57'53" N, 2°06'45" E, 131 m a.s.l.). The station is equipped with a custom-built CO2 analyser (CARIBOU), which is based on a commercial non-dispersive, infrared (NDIR) analyser (Licor 6252), and a coupled gas chromatography (GC) system equipped with an electron capture detector (ECD) and a flame ionization detector (FID) (HP6890N, Agilent) and a reduction gas detector (PP1, Peak Performer). Air intakes, pumping and air drying system are shared between the CARIBOU and the GC systems. The ultimately achieved short-term repeatability (1 sigma, over several days) for the GC system is 0.05 ppm for CO2, 1.4 ppb for CH4, 0.25 ppb for N2O, 0.08 ppb for SF6, 0.88 ppb for CO and 3.8 for H2. The repeatability of the CARIBOU CO2 analyser is 0.06 ppm. In addition to the in situ measurements, weekly flask sampling is performed, and flask air samples are analysed at the Laboratoire des Sciences du Climat et de l'Environnement (LSCE) central laboratory for the same species as well for stable isotopes of CO2. The comparison between in situ measurements and the flask sampling showed averaged differences of 0.08 ± 1.40 ppm for CO2, 0.7 ± 7.3 ppb for CH4, 0.6 ± 0.6 ppb for N2O, 0.01 ± 0.10 ppt for SF6, 1.5± 5.3 ppb for CO and 4.8± 6.9 ppb for H2 for the years 2008–2012. At Trainou station, the mean annual increase rates from 2007 to 2011 at the 180 m sampling height were 2.2 ppm yr−1 for CO2, 4 ppb yr−1 for CH4, 0.78 ppb yr−1 for N2O and 0.29 ppt yr−1 for SF6. For all species, the 180 m sampling level showed the smallest diurnal variation. Mean diurnal gradients between the 50 m and the 180 m sampling level reached up to 30 ppm CO2, 15 ppm CH4 or 0.5 ppb N2O during nighttime whereas the mean gradients are smaller than 0.5 ppm for CO2 and 1.5 ppb for CH4 during afternoon.

Rapid Rhino versus Merocel nasal packs in septal surgery

2011 ◽  
Vol 125 (12) ◽  
pp. 1244-1246 ◽  
Author(s):  
A Hesham ◽  
A Ghali
Keyword(s):  
Standard Deviation ◽  
Pain Score ◽  
Visual Analogue Score ◽  
Nasal Packing ◽  
The Other ◽  
Septal Surgery ◽  
Patient Tolerance ◽  
Operative Complications ◽  
The Mean

AbstractObjective:To compare Rapid Rhino and Merocel packs for nasal packing after septoplasty, in terms of patient tolerance (both with the pack in place and during removal) and post-operative complications.Materials and methods:Thirty patients (aged 18–40 years) scheduled for septoplasty were included. Following surgery, one nasal cavity was packed with Rapid Rhino and the other one with Merocel. Patients were asked to record pain levels on a visual analogue score, on both sides, with the packs in situ and during their removal the next day. After pack removal, bleeding was compared on both sides.Results:The mean ± standard deviation pain score for the Rapid Rhino pack in situ (4.17 ± 1.78) was less than that for the Merocel pack (4.73 ± 2.05), but not significantly so (p = 0.314). The mean pain score for Rapid Rhino pack removal (4.13 ± 1.76) was significantly less that that for Merocel (6.90 ± 1.67; p = 0.001). Bleeding after pack removal was significantly less for the Rapid Rhino sides compared with the Merocel sides (p <0.05).Conclusion:Rapid Rhino nasal packs are less painful and cause less bleeding, compared with Merocel packs, with no side effects. Thus, their use for nasal packing after septal surgery is recommended.

scholarly journals A statistical approach to quantify uncertainty in carbon monoxide measurements at the Izaña global GAW station: 2008–2011

2012 ◽  
Vol 5 (5) ◽  
pp. 6949-6989 ◽  
Author(s):  
A. J. Gomez-Pelaez ◽  
R. Ramos ◽  
V. Gomez-Trueba ◽  
P. C. Novelli ◽  
R. Campo-Hernandez
Keyword(s):  
Carbon Monoxide ◽  
Response Function ◽  
Measurement System ◽  
Minimum Variance ◽  
Standard Uncertainty ◽  
In Situ Measurements ◽  
North East ◽  
The Mean ◽  
Mean Differences

Abstract. Atmospheric CO in-situ measurements are carried out at the Izaña (Tenerife) global GAW mountain station using a RGA (Reduction Gas Analyser). In-situ measurements at Izaña are representative of the subtropical North-East Atlantic free troposphere, specially during the night period. We present the measurement system configuration, the response function, the calibration scheme, the data processing, the Izaña's 2008–2011 CO nocturnal time series, and the mean diurnal cycle by months. We have developed a rigorous uncertainty analysis for carbon monoxide measurements carried out at the Izaña station which could be applied to other GAW stations. We determine the combined standard uncertainty from four components of the measurement: uncertainty of the WMO standard gases interpolated over the range of measurement, the uncertainty that takes into account the agreement between the standard gases and the response function used, the uncertainty due to the repeatability of the injections, and the propagated uncertainty related to the response function parameters uncertainties (which also takes into account the covariance between the parameters). The mean value of the combined standard uncertainty decreased significantly after March 2009, from 2.37 nmol mol−1 to 1.66 nmol mol−1, due to improvements in the measurement system. A fifth type of uncertainty we call representation uncertainty is considered when some of the data necessary to compute exactly the mean are absent. Any computed mean has also a propagated uncertainty arising from the uncertainties of the data used to compute the mean. The law of propagation depends on the type of uncertainty component (random or systematic). In-situ hourly means are compared with simultaneous and collocated NOAA flask samples. The uncertainty in the differences is determined and whether these are significant. For 2009–2011, only 24.5% of the differences are significant, and 68% of the differences are between −2.39 and 2.5 nmol mol−1. Total and annual mean differences are computed using conventional expressions but also expressions with weights based on the minimum variance method. The annual mean differences for 2009–2011 are well within the &amp;pm;2 nmol mol−1 compatibility goal of GAW.

scholarly journals Six years of high-precision quasi-continuous atmospheric greenhouse gas measurements at Trainou Tower (Orléans Forest, France)

2014 ◽  
Vol 7 (1) ◽  
pp. 569-604 ◽  
Author(s):  
M. Schmidt ◽  
M. Lopez ◽  
C. Yver Kwok ◽  
C. Messager ◽  
M. Ramonet ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Atmospheric Measurements ◽  
Short Term ◽  
Gas Detector ◽  
Sampling Height ◽  
The Mean ◽  
Drying System ◽  
Gas Measurements ◽  
Television Tower

Abstract. Results from the Trainou tall tower measurement station installed in 2006, are presented for atmospheric measurements of CO2, CH4, N2O, SF6, CO, H2 mole fractions and Radon-222 activity. Air is sampled from four sampling heights (180 m, 100 m, 50 m and 5 m) of the Trainou 200 m television tower in the Orléans forest in France (47°57'53'' N, 2°06'45'' E, 131 m a.s.l.). The station is equipped with a custom-build CO2 analyzer (CARIBOU), which is based on a commercial NDIR analyser (Licor 6252), and a coupled gas chromatographic GC system equipped with ECD and FID (HP6890N, Agilent) and a reduction gas detector (PP1, Peak Performer). Air intakes, pumping and air drying system are shared between the CARIBOU and the GC systems. After some initial problems, we achieved short-term repeatability (1 sigma, over several days) for the GC system of of 0.05 ppm for CO2, 1.4 ppb for CH4, 0.25 ppb for N2O, 0.08 ppb for SF6, 0.88 ppb for CO and 3.8 for H2. The repeatability of the CARIBOU CO2 analyser is 0.06 ppm. In addition to the in-situ measurements, weekly flask sampling is performed, and flask air samples are analysed at the LSCE central laboratory for the same species as well for stable isotopes of CO2. The comparison between in-situ measurements and the flask sampling showed averaged differences of 0.08 ± 1.4 ppm CO2, 0.69 ± 7.3 ppb CH4, 0.64 ± 0.62 ppb N2O, 0.01 ± 0.1 ppt SF6 and 1.5 ± 5.3 ppb CO for the years 2008–2012. At Trainou station, the mean annual increase rates from 2007 to 2011 at the 180 m sampling height were 2.2 ppm yr−1 for CO2, 4 ppb yr−1 for CH4, 0.78 ppb yr−1 for N2O and 0.29 ppt yr−1 for SF6 respectively. For all species the 180 m sampling level showed the smallest diurnal variation. Mean diurnal gradients between the 50 m and the 180 m sampling level reached up to 30 ppm CO2, 15 ppm CH4 or 0.5 ppb N2O during night whereas the mean gradients are smaller than 0.5 ppm for CO2 and 1.5 ppb for CH4 during afternoon.

scholarly journals In-situ measurements of atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) at the Shangdianzi regional background station, China

2012 ◽  
Vol 12 (5) ◽  
pp. 11151-11173
Author(s):  
B. Yao ◽  
M. K. Vollmer ◽  
L. X. Zhou ◽  
S. Henne ◽  
S. Reimann ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Ratio Method ◽  
High Concentration ◽  
Urban Sector ◽  
Mixing Ratios ◽  
Regional Background ◽  
Hfc 134A ◽  
The Mean ◽  
Measurement Period

Abstract. In-situ measurements of atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) have been conducted at the Shangdianzi (SDZ) Global Atmosphere Watch (GAW) regional background station, China, from May 2010 to May 2011. The time series for 5 HFCs and 4 PFCs periodically showed high concentration events while background conditions occurred for 36% (HFC-32) to 83% (PFC-218) of all measurements. The mean mixing ratios during background conditions for HFC-23, HFC-32, HFC-125, HFC-134a, HFC-152, CF4, PFC-116, PFC-218 and PFC-318 were 24.5, 5.86, 9.97, 66.0, 9.77, 79.1, 4.22, 0.56, 1.28 ppt (parts per trillion, 10−12, molar), respectively. The background mixing ratios for the compounds at SDZ are consistent with those obtained at mid to high latitude sites in the Northern Hemisphere, except for HFC-32 and PFC-318 for which background mixing ratios were not reported in recent years. All HFCs and PFCs show positive trends at rates of 0.7, 1.4, 1.6, 4.1, 1.1, 0.43, 0.05, 0.01, 0.04 ppt yr−1 for HFC-23, HFC-32, HFC-125, HFC-134a, HFC-152, CF4, PFC-116, PFC-218 and PFC-318, respectively. North-easterly winds were connected with small contributions to atmospheric HFCs and PFCs loadings, whereas south-westerly advection (urban sector) showed increased loadings. Chinese emissions were estimated by a tracer ratio method using CO as tracer with rather well known emissions. The emissions, as derived from our measurement period, were 4.4 ± 0.7, 6.9 ± 0.9, 2.5 ± 0.3, 9.0 ± 1.3, 2.2 ± 0.4, 2.1 ± 0.3, 0.24 ± 0.06, 0.07 ± 0.04, 0.45 ± 0.09 kt yr−1 for HFC-23, HFC-32, HFC-125, HFC-134a, HFC-152, CF4, PFC-116, PFC-218, and PFC-318, respectively. The lower HFC-23 emissions compared to earlier studies may be a result of the HFC-23 abatement measures taken as part of the Clean Development Mechanism (CDM) project that started in 2005.

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