Measurement of ozone production sensor

Abstract. A new ambient air monitor, the Measurement of Ozone Production Sensor (MOPS), measures directly the rate of ozone production in the atmosphere. The sensor consists of two 11.3 L environmental chambers made of UV-transmitting Teflon film, a unit to convert NO2 to O3, and a modified ozone monitor. In the sample chamber, flowing ambient air is exposed to the sunlight so that ozone is produced just as it is in the atmosphere. In the second chamber, called the reference chamber, a UV-blocking film over the Teflon film prevents ozone formation but allows other processes to occur as they do in the sample chamber. The air flows that exit the two chambers are sampled by an ozone monitor operating in differential mode so that the difference between the two ozone signals, divided by the residence time in the chambers, gives the ozone production rate. High-efficiency conversion of NO2 to O3 prior to detection in the ozone monitor accounts for differences in the NOx photostationary state that can occur in the two chambers. The MOPS measures the ozone production rate, but with the addition of NO to the sampled air flow, the MOPS can be used to study the sensitivity of ozone production to NO. Preliminary studies with the MOPS on the campus of the Pennsylvania State University show the potential of this new technique.

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Measurement of Ozone Production Sensor

Atmospheric Measurement Techniques ◽

10.5194/amt-3-545-2010 ◽

2010 ◽

Vol 3 (3) ◽

pp. 545-555 ◽

Cited By ~ 31

Author(s):

M. Cazorla ◽

W. H. Brune

Keyword(s):

Production Rate ◽

High Efficiency ◽

Ambient Air ◽

Ozone Production ◽

State University ◽

Photostationary State ◽

Sample Chamber ◽

Efficiency Conversion ◽

The Difference ◽

Teflon Film

Abstract. A new ambient air monitor, the Measurement of Ozone Production Sensor (MOPS), measures directly the rate of ozone production in the atmosphere. The sensor consists of two 11.3 L environmental chambers made of UV-transmitting Teflon film, a unit to convert NO2 to O3, and a modified ozone monitor. In the sample chamber, flowing ambient air is exposed to the sunlight so that ozone is produced just as it is in the atmosphere. In the second chamber, called the reference chamber, a UV-blocking film over the Teflon film prevents ozone formation but allows other processes to occur as they do in the sample chamber. The air flows that exit the two chambers are sampled by an ozone monitor operating in differential mode so that the difference between the two ozone signals, divided by the exposure time in the chambers, gives the ozone production rate. High-efficiency conversion of NO2 to O3 prior to detection in the ozone monitor accounts for differences in the NOx photostationary state that can occur in the two chambers. The MOPS measures the ozone production rate, but with the addition of NO to the sampled air flow, the MOPS can be used to study the sensitivity of ozone production to NO. Preliminary studies with the MOPS on the campus of the Pennsylvania State University show the potential of this new technique.

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Seasonal ozone production rate measurements by use of SAPHIR as a large continuous flow reactor during the JULIAC campaign

10.5194/egusphere-egu21-7963 ◽

2021 ◽

Author(s):

Doreen Niether ◽

Changmin Cho ◽

Franz Rohrer ◽

Andreas Hofzumahaus ◽

Anna Novelli ◽

...

Keyword(s):

Production Rate ◽

Flow Reactor ◽

Lower Troposphere ◽

Ambient Air ◽

Tropospheric Chemistry ◽

Ozone Production ◽

Rural Environment ◽

Oh Radicals ◽

Large Set ◽

Production Rates

For the J&#252;lich Atmospheric Chemistry Project campaign (JULIAC) at Forschungszentrum J&#252;lich (FZJ), Germany, the atmospheric simulation chamber SAPHIR was used as a large photochemical flow reactor to study tropospheric chemistry in a rural environment. From an inlet at 50 m height above ground, ambient air was continuously fed through the chamber and exposed to natural solar radiation. A large set of instrumentation allowed for the measurement of NO, NO2, NO3, N2O5, ClNO2, HCHO, HONO, RO2, HO2, OH, kOH, CO, CO2, CH4, H2O, VOCs, aerosols, and O3 in the sampled air. Intensive measurement phases were performed for one month in each season of 2019. One goal of the JULIAC project was to test our understanding of the chemistry of tropospheric ozone formation.To determine the photochemical net ozone production rate in atmospheric air, OX (O3 + NO2) was measured by commercial instruments at the inlet and inside the well mixed chamber. Through careful characterization of the flow reactor it is possible to predict a reference concentration of OX from the inflow measurements which excludes photochemistry. The measured OX concentration in the chamber was compared with the reference. At night, both concentrations agreed, but during daytime the chamber concentration was enhanced due to photochemical OX production. The difference was used to determine diurnal profiles of the net ozone production with 1 hour time resolution. Production rates up to 15 ppbv/h were observed with an accuracy of 1 ppbV/h. Uncertainties in the offsets of the instruments measuring at the inlet and inside the chamber were identified as large contributors (~0.5 ppbV/h) to the overall error. The measured net ozone production rates are compared to production rates that are expected from the reactions of peroxy radicals (HO2, RO2) with NO, all of which were concurrently measured. The analysis includes other chemical reactions that may produce or destroy ozone or NO2 in the lower troposphere.Good agreement (within 10%) between measured and calculated ozone production rates during the spring and summer campaigns confirms that the main contributions to daytime OX production and destruction in the troposphere are overall governed by the reactions of HO2 and RO2 with NO and the reaction of OH radicals with NO2 in the rural environment studied in this project. The presentation will include a discussion of the role of the OH reactivity from VOCs for the local photochemical ozone production.

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How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-7127-2017 ◽

2017 ◽

Vol 17 (11) ◽

pp. 7127-7142 ◽

Cited By ~ 20

Author(s):

Yudong Yang ◽

Min Shao ◽

Stephan Keßel ◽

Yue Li ◽

Keding Lu ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Production Efficiency ◽

Ambient Air ◽

Early Morning ◽

Chemical Mechanism ◽

Ozone Production ◽

Diurnal Pattern ◽

Volatile Organic ◽

The Difference

Abstract. Total OH reactivity measurements were conducted on the Peking University campus (Beijing) in August 2013 and in Heshan (Guangdong province) from October to November 2014. The daily median OH reactivity was 20 ± 11 s−1 in Beijing and 31 ± 20 s−1 in Heshan, respectively. The data in Beijing showed a distinct diurnal pattern with the maxima over 27 s−1 in the early morning and minima below 16 s−1 in the afternoon. The diurnal pattern in Heshan was not as evident as in Beijing. Missing reactivity, defined as the difference between measured and calculated OH reactivity, was observed at both sites, with 21 % missing reactivity in Beijing and 32 % missing reactivity in Heshan. Unmeasured primary species, such as branched alkenes, could contribute to missing reactivity in Beijing, especially during morning rush hours. An observation-based model with the RACM2 (Regional Atmospheric Chemical Mechanism version 2) was used to understand the daytime missing reactivity in Beijing by adding unmeasured oxygenated volatile organic compounds and simulated intermediates of the degradation from primary volatile organic compounds (VOCs). However, the model could not find a convincing explanation for the missing reactivity in Heshan, where the ambient air was found to be more aged, and the missing reactivity was presumably attributed to oxidized species, such as unmeasured aldehydes, acids and dicarbonyls. The ozone production efficiency was 21 % higher in Beijing and 30 % higher in Heshan when the model was constrained by the measured reactivity, compared to the calculations with measured and modeled species included, indicating the importance of quantifying the OH reactivity for better understanding ozone chemistry.

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High-Efficiency Conversion of CO2 to Oxalate in Water Is Possible Using a Cr-Ga Oxide Electrocatalyst

ACS Catalysis ◽

10.1021/acscatal.8b04327 ◽

2019 ◽

Vol 9 (3) ◽

pp. 2324-2333 ◽

Cited By ~ 12

Author(s):

Aubrey R. Paris ◽

Andrew B. Bocarsly

Keyword(s):

High Efficiency ◽

Efficiency Conversion

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An Integrated Credit-Based Incentive Protocol for Symbol-Level Network-Coded Cooperative Content Distribution among Vehicular Nodes

Applied Sciences ◽

10.3390/app8112035 ◽

2018 ◽

Vol 8 (11) ◽

pp. 2035 ◽

Cited By ~ 1

Author(s):

Ing-Chau Chang ◽

Chin-En Yen ◽

Jacky Lo

Keyword(s):

Ad Hoc ◽

High Efficiency ◽

Performance Metrics ◽

Content Distribution ◽

Long Latency ◽

Distribution Process ◽

Distribution Operations ◽

The Difference ◽

Different Content ◽

Content Information

In traditional symbol-level network coding (SLNC)-based cooperative content distribution approaches, they ignore nodes in the vehicular ad hoc network (VANET) having various network-coded content pieces and distinct levels of interests and selfishness for different kinds of content data, which further prevents these vehicular nodes from forwarding their content information to other nodes. With these approaches, these nodes suffer from the low ratio and the long latency to receive all content information. In this paper, based on distinct levels of node interests and selfishness on different content information, we first categorize vehicular nodes into four classes, that is, the destination, intermediate, irrelevant and overhearing ones and then designate their associated credit-based incentive approaches. Second, we modify the flow of traditional SLNC-based cooperative content distribution operations and propose the content bitmap to realize the difference of network-coded content pieces among vehicular nodes. Further, we rigidly combine the proposed credit-based incentive approach with the modified SLNC-based cooperative content distribution operations in SocialCode to encourage all classes of vehicular nodes to rise their incentives for sharing content data in the cooperative content distribution process. Finally, we perform NS-2 simulations on a street map of downtown Taipei, Taiwan to exhibit the high efficiency of SocialCode over related credit-based incentive approaches by analyzing the following performance metrics, that is, average decoding percentage, file downloading delay and credits, with respect to different file sizes and total numbers of vehicular nodes. As the best knowledge we have, SocialCode is one of the first few researches that works on the integration between the credit-based incentive protocol and the SLNC-based cooperative content distribution.

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Anisotropy Gas Reservoir Drainage Radius and Quantitative Well Interference Study

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.275-277.1285 ◽

2013 ◽

Vol 275-277 ◽

pp. 1285-1291 ◽

Cited By ~ 1

Author(s):

Zheng Long Gao ◽

Hong Fu Fan ◽

Zhi Bin Gao

Keyword(s):

Production Rate ◽

Major Axis ◽

Productivity Analysis ◽

Analysis Method ◽

Equivalent Radius ◽

Average Value ◽

Drainage Radius ◽

Well Spacing ◽

Cumulative Production ◽

The Difference

Unstable productivity analysis method was used to obtain the equivalent radius of 77 wells and the result shows that the equivalent radius ranges from 30 to 970m with an average value of 230m in McKittrick Hills. The difference range of the radius is mainly caused by varying formation properties, gas saturation, production time, etc. Permeability anisotropy changes the drainage from round to ellipse. The major axis and the minor axis of the ellipse are determined by the ratio of major and minor permeability. Current pressure distribution was obtained and was found to be consistent with the modified drainage results, which demonstrates that the unstable productivity analysis method is applicable in the study of gas well drainage radius. An interference well and an observation well’s model was constructed to study well interference quantitatively. When the well spacing is larger than 750m, the productivity will be reduced by 20%. The production rate of interference well is more sensitive to the cumulative production of observation well, when the production rate of interference well is below 16.8×104m3/d.

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Molecular Design of Unsymmetrical Squaraine Dyes for High Efficiency Conversion of Low Energy Photons into Electrons Using TiO2Nanocrystalline Films

Advanced Functional Materials ◽

10.1002/adfm.200900231 ◽

2009 ◽

Vol 19 (17) ◽

pp. 2720-2727 ◽

Cited By ~ 171

Author(s):

Thomas Geiger ◽

Simon Kuster ◽

Jun-Ho Yum ◽

Soo-Jin Moon ◽

Mohammad K. Nazeeruddin ◽

...

Keyword(s):

High Efficiency ◽

Molecular Design ◽

Low Energy ◽

Squaraine Dyes ◽

Efficiency Conversion

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The Student Summer Scientific School “Monitoring of Delta Ecosystems” as an Active Form of Teaching Ecological Methods of Research

Prepodavatel XXI vek ◽

10.31862/2073-9613-2020-2-85-95 ◽

2020 ◽

pp. 85-95

Author(s):

E.G. Rusakova ◽

T.V. Dymova ◽

E.G. Loktionova ◽

A.Yu. Kolotukhin

Keyword(s):

Teaching Methods ◽

Summer School ◽

High Efficiency ◽

Active Form ◽

Scientific School ◽

State University ◽

Competitive Selection ◽

Professional Activities ◽

Active Teaching ◽

Ecological Methods

The article deals with the use of active forms of learning in the work of an environmental summer school. The experience of using active teaching methods in higher education has been studied; examples of summer environmental schools in world and Russian practice are given. The work of the summer school “Monitoring of delta ecosystems”, which took place at Astrakhan State University and the Astrakhan Reserve, is considered. The technology of conducting a summer school is described, starting from the organization of competitive selection of participants and ending with the defense of mini-projects. The criteria for competitive selection are listed taking into account their importance. The summer school program is presented. Using specific examples, the application of active teaching methods in lectures and workshops is examined in detail. Summing up the work of the summer scientific school has shown the high efficiency of using active teaching methods to form the research competencies of its participants and their further professional activities.

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Ozone response to emission changes: a modeling study during the MCMA-2006/MILAGRO campaign

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-23419-2009 ◽

2009 ◽

Vol 9 (6) ◽

pp. 23419-23463 ◽

Cited By ~ 4

Author(s):

J. Song ◽

W. Lei ◽

N. Bei ◽

M. Zavala ◽

B. de Foy ◽

...

Keyword(s):

Control Strategies ◽

Monitoring Network ◽

Ambient Air ◽

Ozone Production ◽

Daily Maximum ◽

Chemical Production ◽

Field Campaign ◽

Ozone Concentrations ◽

Urban Core ◽

Emission Changes

Abstract. The sensitivity of ozone production to precursor emissions was investigated under five different meteorological conditions in the Mexico City Metropolitan Area (MCMA) during the MCMA-2006/MILAGRO field campaign using the gridded photochemical model CAMx driven by observation-nudged WRF meteorology. Precursor emissions were constrained by the comprehensive data from the field campaign and the routine ambient air quality monitoring network. Simulated plume mixing and transport were examined by comparing with measurements from the G-1 aircraft during the campaign. The observed concentrations of ozone precursors and ozone were well reproduced by the model. The effects of reducing precursor emissions on urban ozone production were performed for three representative emission control strategies. A 50% reduction in VOC emissions led to 7 to 22 ppb decrease in daily maximum ozone concentrations, while a 50% reduction in NOx emissions leads to 4 to 21 ppb increase, and 50% reductions in both NOx and VOC emission decrease the daily maximum ozone concentrations up to 10 ppb. These results along with a chemical indicator analysis using the chemical production ratios of H2O2 to HNO3 demonstrate that the MCMA urban core region is VOC-limited for all meteorological episodes, which is consistent with the results from MCMA-2003 field campaign; however the degree of the VOC-sensitivity is higher in the MCMA-2006 due to lower VOC/NOx emission ratio and VOC reactivity. Ozone formation in the surrounding mountain/rural area is mostly NOx-limited, but can be VOC-limited, and the range of the NOx-limited or VOC-limited areas depends on meteorology.

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