scholarly journals Measurement of NO<sub><i>x</i></sub> and NO<sub><i>y</i></sub> with a thermal dissociation cavity ring-down spectrometer (TD-CRDS): instrument characterisation and first deployment

2020 ◽  
Vol 13 (10) ◽  
pp. 5739-5761
Author(s):  
Nils Friedrich ◽  
Ivan Tadic ◽  
Jan Schuladen ◽  
James Brooks ◽  
Eoghan Darbyshire ◽  
...  
Keyword(s):  
Road Traffic ◽  
Trace Gases ◽  
Thermal Dissociation ◽  
Arabian Gulf ◽  
Complete Removal ◽  
Ambient Conditions ◽  
Data Set ◽  
High Particle ◽  
The Impact ◽  
Cavity Ring Down

Abstract. We present a newly constructed, two-channel thermal dissociation cavity ring-down spectrometer (TD-CRDS) for the measurement of NOx (NO+NO2), NOy (NOx+HNO3+RO2NO2+2N2O5 etc.), NOz (NOy−NOx) and particulate nitrate (pNit). NOy-containing trace gases are detected as NO2 by the CRDS at 405 nm following sampling through inlets at ambient temperature (NOx) or at 850 ∘C (NOy). In both cases, O3 was added to the air sample directly upstream of the cavities to convert NO (either ambient or formed in the 850 ∘C oven) to NO2. An activated carbon denuder was used to remove gas-phase components of NOy when sampling pNit. Detection limits, defined as the 2σ precision for 1 min averaging, are 40 pptv for both NOx and NOy. The total measurement uncertainties (at 50 % relative humidity, RH) in the NOx and NOy channels are 11 %+10 pptv and 16 %+14 pptv for NOz respectively. Thermograms of various trace gases of the NOz family confirm stoichiometric conversion to NO2 (and/or NO) at the oven temperature and rule out significant interferences from NH3 detection (<2 %) or radical recombination reactions under ambient conditions. While fulfilling the requirement of high particle transmission (>80 % between 30 and 400 nm) and essentially complete removal of reactive nitrogen under dry conditions (>99 %), the denuder suffered from NOx breakthrough and memory effects (i.e. release of stored NOy) under humid conditions, which may potentially bias measurements of particle nitrate. Summertime NOx measurements obtained from a ship sailing through the Red Sea, Indian Ocean and Arabian Gulf (NOx levels from <20 pptv to 25 ppbv) were in excellent agreement with those taken by a chemiluminescence detector of NO and NO2. A data set obtained locally under vastly different conditions (urban location in winter) revealed large diel variations in the NOz to NOy ratio which could be attributed to the impact of local emissions by road traffic.

scholarly journals Measurement of NO<sub><i>x</i></sub> and NO<sub><i>y</i></sub> with a thermal dissociation cavity ring-down spectrometer (TD-CRDS): Instrument characterisation and first deployment

2020 ◽  
Author(s):  
Nils Friedrich ◽  
Ivan Tadic ◽  
Jan Schuladen ◽  
James Brooks ◽  
Eoghan Darbyshire ◽  
...  
Keyword(s):  
Thermal Dissociation ◽  
Arabian Gulf ◽  
Complete Removal ◽  
Ambient Conditions ◽  
High Particle ◽  
Dry Conditions ◽  
Air Sample ◽  
Recombination Reactions ◽  
Rule Out ◽  
Cavity Ring Down

Abstract. We present a newly constructed, two channel Thermal Dissociation Cavity Ring-Down Spectrometer (TD-CRDS) for the detection of NOx (NO + NO2), NOy (NOx + HNO3 + RO2NO2 + N2O5 etc.), NOz (NOy – NOx) and particulate nitrate (pNit). NOy-containing trace gases are detected as NO2 by CRDS at 405 nm following sampling through inlets at ambient temperature (NOx), or at 850 °C (NOy). In both cases, O3 was added to the air sample directly upstream of the cavities to convert NO (either ambient, or formed in the 850 °C oven) to NO2. An activated carbon denuder was used to remove gas-phase components of NOy when sampling pNit. Detection limits (1 minute averaging) for NOx, NOy and NOz are 98, 51 and 110 pptv, respectively. The total measurement uncertainties (at 50 % RH) in the NOx and NOy channels are 11 % + 10 pptv and 16 % + 14 pptv for NOz, respectively. Thermograms of various NOz species (peroxyacetyl nitrate, isopropyl nitrate, and HNO3) confirm stoichiometric conversion to NO2 (and/or NO) at the oven temperature and rule out significant interferences from NH3 detection or radical recombination reactions under ambient conditions. While fulfilling the requirement of high particle transmission and essentially complete removal of reactive nitrogen under dry conditions, the denuder suffered from NOx breakthrough and memory effects (i.e. release of stored NOy) under humid conditions. NOx measurements obtained from a ship sailing through the Red Sea, Indian Ocean and Arabian Gulf (NOx levels from

Impact of Major Road Supply on Individual Travel Time Expenditure: An Exploration with a 30-Year Variation of Infrastructure and Travel

2018 ◽  
Vol 2672 (3) ◽  
pp. 56-68
Author(s):  
Ryosuke Abe ◽  
Kay W. Axhausen
Keyword(s):  
Travel Time ◽  
Large Scale ◽  
Travel Demand ◽  
Road Traffic ◽  
Land Development ◽  
Transportation Infrastructure ◽  
Major Road ◽  
Birth Cohorts ◽  
Data Set ◽  
The Impact

This study estimates the impact of major road supply on individual travel time expenditures (TTEs) using data that cover 30-year variations in transportation infrastructure and travel behavior. The impacts of the supply of road and rail infrastructure are estimated with a data set that combines records of large-scale household travel surveys in the Tokyo metropolitan area conducted in 1978, 1988, 1998, and 2008. Linear and Tobit models of individual TTEs are estimated by following the behavior of birth cohorts over the 30-year period. The models incorporate the changes in transportation infrastructure, measured as lane kilometers of two levels of major road stock and vehicle kilometers of urban rail service. The results show significant negative effects of lane kilometers for higher-level and lower-level major roads on the TTEs for all travel purposes and for commuting, after controlling for socioeconomic backgrounds and generations of individuals. This study discusses that, in Tokyo, the estimated effect is more likely to reflect the effect of a major road network per se on individual TTEs than the (indirect) effect of major road supply on individual TTEs working through land development activities (i.e., induced car travel demand). For example, the caveat is that actual road investment decisions still need to consider the induced component of road traffic in addition to the (direct) effect that is estimated in this study.

scholarly journals A gas chromatograph for quantification of peroxycarboxylic nitric anhydrides calibrated by thermal dissociation cavity ring-down spectroscopy

2014 ◽  
Vol 7 (6) ◽  
pp. 5953-6019
Author(s):  
T. W. Tokarek ◽  
J. A. Huo ◽  
C. A. Odame-Ankrah ◽  
D. Hammoud ◽  
Y. M. Taha ◽  
...  
Keyword(s):  
Thermal Dissociation ◽  
Ambient Air ◽  
Calibration Method ◽  
Ionization Mass ◽  
Molecular Formula ◽  
Data Set ◽  
Cavity Ring Down Spectroscopy ◽  
Mixing Ratios ◽  
Advantages And Disadvantages ◽  
Cavity Ring Down

Abstract. The peroxycarboxylic nitric anhydrides (PANs, molecular formula RC(O)O2NO2) can readily be observed by gas chromatography coupled to electron capture detection (PAN-GC). Calibration of a PAN-GC remains a challenge because the response factors (RF's) differ for each of the PANs and because their synthesis in sufficiently high purity is non-trivial, in particular for PANs containing unsaturated side chains. In this manuscript, a PAN-GC and its calibration using diffusion standards, whose output was quantified by blue diode laser thermal dissociation cavity ring-down spectroscopy (TD-CRDS), are described. The PAN-GC peak areas correlated linearly with total peroxy nitrate (ΣPN) mixing ratios measured by TD-CRDS (r > 0.96). Accurate determination of RF's required the concentrations of PAN impurities in the synthetic standards to be subtracted from ΣPN. The PAN-GC and its TD-CRDS calibration method were deployed during ambient air measurement campaigns in Abbotsford, BC, from 20 July to 5 August, 2012, and during the Fort McMurray Oil Sands Strategic Investigation of Local Sources (FOSSILS) campaign at the AMS13 ground site in Fort McKay, AB, from 10 August to 5 September 2013. For the Abbotsford data set, the PAN-GC mixing ratios were compared and agreed with those determined in parallel by thermal dissociation chemical ionization mass spectrometry (TD-CIMS). Advantages and disadvantages of the PAN measurement techniques used in this work and the utility of TD-CRDS as a PAN-GC calibration method are discussed.

scholarly journals A gas chromatograph for quantification of peroxycarboxylic nitric anhydrides calibrated by thermal dissociation cavity ring-down spectroscopy

2014 ◽  
Vol 7 (10) ◽  
pp. 3263-3283 ◽  
Author(s):  
T. W. Tokarek ◽  
J. A. Huo ◽  
C. A. Odame-Ankrah ◽  
D. Hammoud ◽  
Y. M. Taha ◽  
...  
Keyword(s):  
Thermal Dissociation ◽  
Ambient Air ◽  
Calibration Method ◽  
Molecular Formula ◽  
Response Factors ◽  
Data Set ◽  
Cavity Ring Down Spectroscopy ◽  
Mixing Ratios ◽  
Advantages And Disadvantages ◽  
Cavity Ring Down

Abstract. The peroxycarboxylic nitric anhydrides (PANs, molecular formula: RC(O)O2NO2) can readily be observed by gas chromatography (PAN-GC) coupled to electron capture detection. Calibration of a PAN-GC remains a challenge, because the response factors differ for each of the PANs, and because their synthesis in sufficiently high purity is non-trivial, in particular for PANs containing unsaturated side chains. In this manuscript, a PAN-GC and its calibration using diffusion standards, whose output was quantified by blue diode laser thermal dissociation cavity ring-down spectroscopy (TD-CRDS), are described. The PAN-GC peak areas correlated linearly with total peroxy nitrate (ΣPN) mixing ratios measured by TD-CRDS (r > 0.96). Accurate determination of response factors required the concentrations of PAN impurities in the synthetic standards to be subtracted from ΣPN. The PAN-GC and its TD-CRDS calibration method were deployed during ambient air measurement campaigns in Abbotsford, BC, from 20 July to 5 August 2012, and during the Fort McMurray Oil Sands Strategic Investigation of Local Sources (FOSSILS) campaign at the AMS13 ground site in Fort McKay, AB, from 10 August to 5 September 2013. The PAN-GC limits of detection for PAN, PPN, and MPAN during FOSSILS were 1, 2, and 3 pptv, respectively. For the Abbotsford data set, the PAN-GC mixing ratios were compared, and agreed with those determined in parallel by thermal dissociation chemical ionization mass spectrometry (TD-CIMS). Advantages and disadvantages of the PAN measurement techniques used in this work and the utility of TD-CRDS as a PAN-GC calibration method are discussed.

scholarly journals Specifics of the traffic scene identification problem observed at level crossings, analysed from the train driver’s perspective

2021 ◽  
Vol 58 (2) ◽  
pp. 81-97
Author(s):  
Jakub Młyńczak ◽  
Piotr Folęga ◽  
Ireneusz Celiński
Keyword(s):  
Eye Tracking ◽  
Traffic Safety ◽  
Road Traffic ◽  
Transport Infrastructure ◽  
Level Crossing ◽  
Data Set ◽  
Level Crossings ◽  
Rail Vehicle ◽  
Tracking Devices ◽  
The Impact

Level crossing is an element of the transport infrastructure of a particular type. This is where streams of regulated and unregulated traffic interact. Vehicles of regulated, rail traffic affect on unregulated, road traffic vehicles. This process takes place over a relatively small area. But the associated processes are concerned with long distances and medium speeds. Importantly, the impact may be mutual (mainly on level crossing cat. D). Consequently, a number of diverse problems can be observed at level crossings as well as in their direct vicinity. One of them is very particular, since its intensity and scale are significantly higher compared to other points of the transport network. This is a problem of how the sight organs of a rail vehicle driver function. At level crossings, a rail vehicle driver is incapable of registering all events connected with moving objects in a horizontal plane of the field of view (often, dozens or hundreds of vehicles and pedestrians, rail vehicles, signs etc.). Especially in agglomeration areas, near the railway stations, people may violently trespass into the tracks. Before reaching a level crossing, the driver’s sight organs perform specific movements of variable dynamics, having a direct impact on the traffic safety. Given the context in question, the article discusses the methods used to measure the characteristics of the train driver’s sight organs by means of eye tracking devices. The measured characteristics are: saccadic movements, fixation point locations, blinking etc. The relevant studies were supported by using additional equipment and techniques, including visual and vibroacoustic ones. These studies have been illustrated with reference to the measurements performed in different sections of the railway network. The aim of the research was to analyse the behaviour of drivers of traction vehicles. The research results have been discussed in quantitative terms, thus introducing several new descriptive characteristics. The data thus obtained, e.g. concerning the functions of the driver’s sight organs, have been analysed using numerical data set characteristics. With regard to the context this article the authors also conduct research addresses measurements of the characteristics of the road vehicle driver’s sight organs performed by means of eye tracking devices.

scholarly journals IMPACT ANALYSIS OF ACCIDENTS ON THE TRAFFIC FLOW BASED ON MASSIVE FLOATING CAR DATA

2021 ◽  
Vol XLIII-B4-2021 ◽  
pp. 95-102
Author(s):  
J. Golze ◽  
U. Feuerhake ◽  
C. Koetsier ◽  
M. Sester
Keyword(s):  
Traffic Flow ◽  
Impact Analysis ◽  
Road Traffic ◽  
Movement Behavior ◽  
Speed Profile ◽  
Temporal Dimension ◽  
Data Set ◽  
The Road ◽  
Movement Trajectories ◽  
The Impact

Abstract. The wide usage of GPS-equipped devices enables the mass recording of vehicle movement trajectories describing the movement behavior of the traffic participants. An important aspect of the road traffic is the impact of anomalies, like accidents, on traffic flow. Accidents are especially important as they contribute to the the aspects of safety and also influence travel time estimations. In this paper, the impact of accidents is determined based on a massive GPS trajectory and accident dataset. Due to the missing precise date of the accidents in the data set used, first, the date of the accident is estimated based on the speed profile at the accident time. Further, the temporal impact of the accident is estimated using the speed profile of the whole day. The approach is applied in an experiment on a one month subset of the datasets. The results show that more than 72% of the accident dates are identified and the impact on the temporal dimension is approximated. Moreover, it can be seen that accidents during the rush hours and on high frequency road types (e.g. motorways, trunks or primaries) have an increasing effect on the impact duration on the traffic flow.

Age at Exposure to Parental Suicide and the Subsequent Risk of Suicide in Young People

Crisis ◽  
2018 ◽  
Vol 39 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Kuan-Ying Lee ◽  
Chung-Yi Li ◽  
Kun-Chia Chang ◽  
Tsung-Hsueh Lu ◽  
Ying-Yeh Chen
Keyword(s):  
Young People ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Cox Proportional Hazards ◽  
Cox Proportional Hazards Model ◽  
Birth Registry ◽  
Data Set ◽  
Parental Suicide ◽  
The Impact ◽  
Age At Exposure

Abstract. Background: We investigated the age at exposure to parental suicide and the risk of subsequent suicide completion in young people. The impact of parental and offspring sex was also examined. Method: Using a cohort study design, we linked Taiwan's Birth Registry (1978–1997) with Taiwan's Death Registry (1985–2009) and identified 40,249 children who had experienced maternal suicide (n = 14,431), paternal suicide (n = 26,887), or the suicide of both parents (n = 281). Each exposed child was matched to 10 children of the same sex and birth year whose parents were still alive. This yielded a total of 398,081 children for our non-exposed cohort. A Cox proportional hazards model was used to compare the suicide risk of the exposed and non-exposed groups. Results: Compared with the non-exposed group, offspring who were exposed to parental suicide were 3.91 times (95% confidence interval [CI] = 3.10–4.92 more likely to die by suicide after adjusting for baseline characteristics. The risk of suicide seemed to be lower in older male offspring (HR = 3.94, 95% CI = 2.57–6.06), but higher in older female offspring (HR = 5.30, 95% CI = 3.05–9.22). Stratified analyses based on parental sex revealed similar patterns as the combined analysis. Limitations: As only register-­based data were used, we were not able to explore the impact of variables not contained in the data set, such as the role of mental illness. Conclusion: Our findings suggest a prominent elevation in the risk of suicide among offspring who lost their parents to suicide. The risk elevation differed according to the sex of the afflicted offspring as well as to their age at exposure.

State Medical Boards' Perceptions of a Minimum Data Set and Current Practices for Collecting Physician Information

2013 ◽  
Vol 99 (4) ◽  
pp. 40-45 ◽  
Author(s):  
Aaron Young ◽  
Philip Davignon ◽  
Margaret B. Hansen ◽  
Mark A. Eggen
Keyword(s):  
Media Coverage ◽  
The United States ◽  
Minimum Data Set ◽  
Direct Patient Care ◽  
Physician Workforce ◽  
Data Set ◽  
Minimum Data ◽  
State Medical Boards ◽  
The Impact ◽  
Current Practices

ABSTRACT Recent media coverage has focused on the supply of physicians in the United States, especially with the impact of a growing physician shortage and the Affordable Care Act. State medical boards and other entities maintain data on physician licensure and discipline, as well as some biographical data describing their physician populations. However, there are gaps of workforce information in these sources. The Federation of State Medical Boards' (FSMB) Census of Licensed Physicians and the AMA Masterfile, for example, offer valuable information, but they provide a limited picture of the physician workforce. Furthermore, they are unable to shed light on some of the nuances in physician availability, such as how much time physicians spend providing direct patient care. In response to these gaps, policymakers and regulators have in recent years discussed the creation of a physician minimum data set (MDS), which would be gathered periodically and would provide key physician workforce information. While proponents of an MDS believe it would provide benefits to a variety of stakeholders, an effort has not been attempted to determine whether state medical boards think it is important to collect physician workforce data and if they currently collect workforce information from licensed physicians. To learn more, the FSMB sent surveys to the executive directors at state medical boards to determine their perceptions of collecting workforce data and current practices regarding their collection of such data. The purpose of this article is to convey results from this effort. Survey findings indicate that the vast majority of boards view physician workforce information as valuable in the determination of health care needs within their state, and that various boards are already collecting some data elements. Analysis of the data confirms the potential benefits of a physician minimum data set (MDS) and why state medical boards are in a unique position to collect MDS information from physicians.

The Impact of Green Labels on U.S. Hotel Net Operating Income: Operating Statements Analyses

2019 ◽  
Vol 11 (1) ◽  
pp. 156-173
Author(s):  
Spenser Robinson ◽  
A.J. Singh
Keyword(s):  
Environmental Design ◽  
Green Buildings ◽  
Small Sample ◽  
Sample Survey ◽  
Data Set ◽  
Operating Income ◽  
Energy Star ◽  
The Impact ◽  
Industry Professionals

This paper shows Leadership in Energy and Environmental Design (LEED) certified hospitality properties exhibit increased expenses and earn lower net operating income (NOI) than non-certified buildings. ENERGY STAR certified properties demonstrate lower overall expenses than non-certified buildings with statistically neutral NOI effects. Using a custom sample of all green buildings and their competitive data set as of 2013 provided by Smith Travel Research (STR), the paper documents potential reasons for this result including increased operational expenses, potential confusion with certified and registered LEED projects in the data, and qualitative input. The qualitative input comes from a small sample survey of five industry professionals. The paper provides one of the only analyses on operating efficiencies with LEED and ENERGY STAR hospitality properties.

Does Tax Increment Financing Pass the “But-for” Test in Missouri?

2019 ◽  
Vol 33 (3) ◽  
pp. 187-202
Author(s):  
Ahmed Rachid El-Khattabi ◽  
T. William Lester
Keyword(s):  
Economic Development ◽  
Kansas City ◽  
Time Series Data ◽  
Local Level ◽  
Conclusive Evidence ◽  
Series Data ◽  
Tax Increment Financing ◽  
Data Set ◽  
Development Indicators ◽  
The Impact

The use of tax increment financing (TIF) remains a popular, yet highly controversial, tool among policy makers in their efforts to promote economic development. This study conducts a comprehensive assessment of the effectiveness of Missouri’s TIF program, specifically in Kansas City and St. Louis, in creating economic opportunities. We build a time-series data set starting 1990 through 2012 of detailed employment levels, establishment counts, and sales at the census block-group level to run a set of difference-in-differences with matching estimates for the impact of TIF at the local level. Although we analyze the impact of TIF on a wide set of indicators and across various industry sectors, we find no conclusive evidence that the TIF program in either city has a causal impact on key economic development indicators.

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