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Use of reactive tracers to determine ambient OH radical concentrations: Application within the indoor environment
Dudley E. Shallcross, Keven C Clemitshaw, Guy C Lloyd-Jones, Graham Nickless, Stephen J Henshaw, Fredrik K Petersson, Maria Paz Muñoz, Damien Martin, Iain R White, 2010, izvirni znanstveni članek

Opis: The hydroxyl radical (OH) plays a key role in determining indoor air quality. However, its highly reactive nature and low concentration indoors impede direct analysis. This paper describes the techniques used to indirectly quantify indoor OH, including the development of a new method based on the instantaneous release of chemical tracers into the air. This method was used to detect ambient OH in two indoor seminar rooms following tracer detection by gas chromatography- mass spectrometry (GCMS). The results from these tests add to the small number of experiments that have measured indoor OH which are discussed with regard to future directions within air quality research.
Najdeno v: osebi
Ključne besede: Ozone, Indoor air pollution, Indoor ozone, chemical tracers
Objavljeno: 18.07.2019; Ogledov: 659; Prenosov: 0
.pdf Polno besedilo (153,74 KB)

A feasibility study of the use of reactive tracers to determine outdoor daytime OH radical concentrations within the urban environment
Iain R White, Damien Martin, K Fredrik Petersson, Stephen J Henshaw, Graham Nickless, Guy C Lloyd-Jones, Kevin C Clemitshaw, Dudley E Shallcross, 2014, izvirni znanstveni članek

Opis: Using a specifically designed chemical tracer to indirectly measure local atmospheric hydroxyl radical (OH) concentrations is a very appealing concept. Such a tracer will provide information on the amount of OH a tracer encounters, as it moves through the urban environment and provide a stringent test of models. However, to date an outdoor experiment such as this has not been conducted. This article discusses the reasons why this is so and examines the feasibility of using tracers to measure integrated urban OH levels over short (≤1km) distances.
Najdeno v: osebi
Ključne besede: reactive tracers, OH radicals, NO3 radicals, oxidising rate, dispersion, urban
Objavljeno: 18.07.2019; Ogledov: 696; Prenosov: 0
.pdf Polno besedilo (748,36 KB)

Tracer concentration profiles measured in central London as part of the REPARTEE campaign
Damien Martin, K Fredrik Petersson, Iain R White, Stephen H Henshaw, Graham Nickless, Amy Lovelock, Janet F Barlow, Tyrone Dunbar, Curtis R Wood, Dudley E. Shallcross, 2011, izvirni znanstveni članek

Opis: There have been relatively few tracer experiments carried out that have looked at vertical plume spread in urban areas. In this paper we present results from two tracer (cyclic perfluorocarbon) experiments carried out in 2006 and 2007 in central London centred on the BT Tower as part of the REPARTEE (Regent's Park and Tower Environmental Experiment) campaign. The height of the tower gives a unique opportunity to study vertical dispersion profiles and transport times in central London. Vertical gradients are contrasted with the relevant Pasquill stability classes. Estimation of lateral advection and vertical mixing times are made and compared with previous measurements. Data are then compared with a simple operational dispersion model and contrasted with data taken in central London as part of the DAPPLE campaign. This correlates dosage with non-dimensionalised distance from source. Such analyses illustrate the feasibility of the use of these empirical correlations over these prescribed distances in central London.
Najdeno v: osebi
Ključne besede: advection, concentration (composition), dispersion, tracer, urban atmosphere, vertical mixing, vertical profile
Objavljeno: 18.07.2019; Ogledov: 747; Prenosov: 0
.pdf Polno besedilo (1,49 MB)

Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): An overview of the REPARTEE experiment and its conclusions
Gavin J Phillips, Carole Helfter, Chiara F Di Marco, Eiko Nemitz, Fay Davies, Janet F Barlow, Tyrone Dunbar, Iain R White, Dudley E Shallcross, Stephen J Henshaw, K Fredrik Peterson, Brian Davison, Damien Martin, Ben Langford, C Nicholas Hewitt, Stephen M Ball, Justin M Langridge, A K Benton, Roderick L Jones, Paul I Williams, John Whitehead, Martin W Gallagher, Claire Martin, James R Dorsey, Hugh Coe, James D Allan, William J Bloss, Alistair J Thorpe, David C S Beddows, Manuel DallOsto, Roy M Harrison, Steven Smith, 2012, pregledni znanstveni članek

Opis: The Regents Park and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160-190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a) demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b) generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c) quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d) generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e) provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f) the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g) studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h) new information on the chemical composition and source apportionment of particulate matter size fractions in the atmosphere of London derived both from bulk chemical analysis and aerosol mass spectrometry with two instrument types.
Najdeno v: osebi
Ključne besede: megacity, trace gas, urban atmosphere, atmospheric transport, chemical composition, aerosol
Objavljeno: 18.07.2019; Ogledov: 768; Prenosov: 0
.pdf Polno besedilo (4,66 MB)

Evaluation of VOC denuder efficiency and positive artefactdue to denuder breakthrough using TCA08
Asta Gregorič, Gašper Lavrič, Martin Rigler, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: osebi
Ključne besede: VOC denuder, TCA08, sampling artefact
Objavljeno: 17.07.2019; Ogledov: 811; Prenosov: 0
.pdf Polno besedilo (6,60 MB)

The new instrument using a TC–BC (total carbon–black carbon) method for the online measurement of carbonaceous aerosols
Martin Rigler, Luka Drinovec, Gašper Lavrič, Anastasia Vlachou, Andre S. H. Prevot, Jean-Luc Jaffrezo, Iasonas Stavroulas, Jean Sciare, Judita Burger, Irena Krajnc, Janja Turšič, Anthony D. A. Hansen, Griša Močnik, 2020, izvirni znanstveni članek

Opis: We present a newly developed total carbon analyzer (TCA08) and a method for online speciation of carbonaceous aerosol with a high time resolution. The total carbon content is determined by flash heating of a sample collected on a quartz-fiber filter with a time base between 20 min and 24 h. The limit of detection is approximately 0.3 µg C, which corresponds to a concentration of 0.3 µg C m−3 at a sample flow rate of 16.7 L min−1 and a 1 h sampling time base. The concentration of particulate equivalent organic carbon (OC) is determined by subtracting black carbon concentration, concurrently measured optically by an Aethalometer®, from the total carbon concentration measured by the TCA08. The combination of the TCA08 and Aethalometer (AE33) is an easy-to-deploy and low-maintenance continuous measurement technique for the high-time-resolution determination of equivalent organic and elemental carbon (EC) in different particulate matter size fractions, which avoids pyrolytic correction and the need for high-purity compressed gases. The performance of this online method relative to the standardized off-line thermo-optical OC–EC method and respective instruments was evaluated during a winter field campaign at an urban background location in Ljubljana, Slovenia. The organic-matter-to-organic-carbon ratio obtained from the comparison with an aerosol chemical speciation monitor (ACSM) was OM/OC=1.8, in the expected range.
Najdeno v: osebi
Ključne besede: total carbon, aeroosl, black carbon, carbonaceous matter
Objavljeno: 17.08.2020; Ogledov: 351; Prenosov: 11
.pdf Polno besedilo (226,45 KB)

Short-range urban dispersion experiments using fixed and moving sources
Stephen E Belcher, Alison S Tomlin, James Tate, Marina K Neophytou, Rex E Britter, Fredrik Petterson, Iain R White, Graham Nickless, Catheryn S Price, Damien Martin, Dudley E. Shallcross, Janet F Barlow, Alan Robins, 2009, izvirni znanstveni članek

Opis: Four perfluorocarbon tracer dispersion experiments were carried out in central London, United Kingdom in 2004. These experiments were supplementary to the dispersion of air pollution and penetration into the local environment (DAPPLE) campaign and consisted of ground level releases, roof level releases and mobile releases; the latter are believed to be the first such experiments to be undertaken. A detailed description of the experiments including release, sampling, analysis and wind observations is given. The characteristics of dispersion from the fixed and mobile sources are discussed and contrasted, in particular, the decay in concentration levels away from the source location and the additional variability that results from the non-uniformity of vehicle speed.
Najdeno v: osebi
Ključne besede: dapple, perfluorocarbon, tracer, mobile source
Objavljeno: 18.07.2019; Ogledov: 680; Prenosov: 0
.pdf Polno besedilo (265,68 KB)

Anaerobic Co-Digestion of Ligno-Cellulosic degradation products - Wood Resin Residue from Tannin Production
Gregor Draago Zupančič, Mario Panjicko, Domagoj Eršek, Goran Lukić, Žiga Velišček, Martin Gojun, 2018, objavljeni znanstveni prispevek na konferenci

Opis: Tannin is a very versatile industrial material used for many applications. During tannin production, a residue is produced, which consists of 10 – 15 % sodium acetate solution with up to 10 % water-soluble wood resins by mass. Since it contains a high portion of acetate, it can be useful for anaerobic digestion to produce biomethane, whereas wood resins may exhibit inhibitory effects. In order to test the biodegradability of wood resin residue, several batch tests were performed with two approaches. In the first approach, co-digestion with corn-silage and animal waste was performed utilizing suspended biomass inoculum. In the second approach, co-digestion with pulp and paper wastewater was performed utilizing granular biomass inoculum. In the first approach, the results showed partial inhibition of degradation using mixtures of 25.6 % and total inhibition using 100.0 % of wood resin. Maximum biodegradability achieved was 83.4 %. In the second approach, the results showed partial inhibition of degradation using mixtures of 1.7 and 3.3 % of wood resin. Maximum biodegradability achieved was 64.3 %. Because the second approach enabled us to process larger quantities of wood resin (larger COD load), a pilot experiment of anaerobic co-digestion with pulp and paper wastewater was performed, utilising similar conditions to the considered full-scale treatment. The results showed COD degradation between 70.1 and 81.7 % and a potential increase in total produced biomethane of 36 – 39 %, with no significant adverse effects. Wood resin residue yielded 45 – 50 m3 of biomethane per tonne, which exhibits a good potential for biomethane production. If used for biomethane production in pulp and paper wastewater treatment, the valorisation value of the wood resin residue is between 54,500 € and 94,000 €, which makes the presented treatment also an economically viable option.
Najdeno v: osebi
Ključne besede: Anaerobic digestion, biomethane production, wood resin residue
Objavljeno: 11.03.2020; Ogledov: 693; Prenosov: 0
.pdf Polno besedilo (666,01 KB)

Prenova montažnega procesa v podjetju Agromehanika Kranj
Martin Hočevar, 2020, diplomsko delo

Opis: Podjetje Agromehanika v celoti prenavlja poslovne procese, v diplomskem delu pa smo se v okviru prenove proizvodnih procesov omejili na prenovo montažnega procesa. Podjetje se občasno srečuje s problemom predolgih dobavnih rokov, zato smo si zastavili ambiciozen cilj: skrajšati čas montaže za 30 %. Proučili smo teoretična dognanja, nato pa naredili analizo obstoječega stanja: izmerili in narisali velikost montažne delavnice, popisali potrebno opremo ter ugotovili razpoložljivo število montažnih delavcev pri obstoječem načinu montaže. Pridobili smo kosovnico za izbrani izdelek, potem pa merili čase posameznih operacij ter narisali in opisali zaporedje izvajanja le-teh. Sledilo je načrtovanje prenove montažnega procesa za izbrani proizvod. Projekt prenove montažnega procesa smo vodili s precedenčnim diagramom. Za oskrbo z vijačnim materialom smo uvedli sistem KANBAN. Ločili smo logistično in montažno funkcijo. Odločili smo se za ravno linijsko postavitev in uvedli izboljšave v procesu montaže. Rezultat prenove montažnega procesa za izbrani proizvod je bil znižanje časa montaže za 41,57 % v pilotni liniji brez dodatnih investicij in 64,25 % v predvideni liniji z dodatnimi investicijami. Prihranek časa pri delu montažnih delavcev smo ovrednotili tudi finančno. Prenova montažnega procesa podjetju zagotavlja končne proizvode, razpoložljive v krajšem času kot doslej. S tem je skrajšan dobavni rok, ki je kupcem ključnega pomena v času, ko pridobijo državne subvencije za razvoj kmetijstva, ki jih morajo črpati v predvidenem roku. Zato ima prenova montažnega procesa za podjetje multiplikativen pozitiven učinek, s katerim obdrži obstoječe stranke, s krajšimi dobavnimi časi pa morda pridobi tudi nove.
Najdeno v: osebi
Ključne besede: prenova, poslovni proces, proizvodni proces, montažni proces, vitka proizvodnja, sistem KANBAN, »ravno pravočasno«, linija, operacija, precedenčni diagram
Objavljeno: 28.10.2020; Ogledov: 240; Prenosov: 15
.pdf Polno besedilo (1,42 MB)

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