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Dr. Leonidas Ntziachristos
Mechanical Engineering Department, Aristotle University of Thessaloniki, P.O. Box 458, GR 54124, Thessaloniki, Greece

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0 Ship emissions
0 vehicle emissions
0 Emission inventorying
0 Exhaust particles
0 Emission models

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Exhaust particles
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Emission inventorying

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Journal article
Published: 16 February 2021 in Sensors
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Attention to Black Carbon (BC) has been rising due to its effects on human health as well its contribution to climate change. Measurements of BC are challenging, as currently used devices are either expensive or impractical for continuous monitoring. Here, we propose an optoacoustic sensor to address this problem. The sensor utilizes a novel ellipsoidal design for refocusing the optoacoustic signal with minimal acoustic energy losses. To reduce the cost of the system, without sacrificing accuracy, an overdriven laser diode and a Quartz Tuning Fork are used as the light source and the sound detector, respectively. The prototype was able to detect BC particles and to accurately monitor changes in concentration in real time and with very good agreement with a reference instrument. The response of the sensor was linearly dependent on the BC particles concentration with a normalized noise equivalent absorption coefficient (NNEA) for soot equal to 7.39 × 10−9 W cm−1 Hz−1/2. Finally, the prototype was able to perform NO2 measurements, demonstrating its ability to accurately monitor both particulate and gaseous pollutants. The proposed sensor has the potential to offer a significant economic impact for BC environmental measurements and source appointment technologies.

ACS Style

Antonios Stylogiannis; Nikolaos Kousias; Anastasios Kontses; Leonidas Ntziachristos; Vasilis Ntziachristos. A Low-Cost Optoacoustic Sensor for Environmental Monitoring. Sensors 2021, 21, 1379 .

AMA Style

Antonios Stylogiannis, Nikolaos Kousias, Anastasios Kontses, Leonidas Ntziachristos, Vasilis Ntziachristos. A Low-Cost Optoacoustic Sensor for Environmental Monitoring. Sensors. 2021; 21 (4):1379.

Chicago/Turabian Style

Antonios Stylogiannis; Nikolaos Kousias; Anastasios Kontses; Leonidas Ntziachristos; Vasilis Ntziachristos. 2021. "A Low-Cost Optoacoustic Sensor for Environmental Monitoring." Sensors 21, no. 4: 1379.

Journal article
Published: 19 January 2021 in Sustainability
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A vehicle’s air drag coefficient (Cd) and rolling resistance coefficient (RRC) have a significant impact on its fuel consumption. Consequently, these properties are required as input for the certification of the vehicle’s fuel consumption and Carbon Dioxide emissions, regardless of whether the certification is done via simulation or chassis dyno testing. They can be determined through dedicated measurements, such as a drum test for the tire’s rolling resistance coefficient and constant speed test (EU) or coast down test (US) for the body’s air Cd. In this paper, a methodology that allows determining the vehicle’s Cd∙A (the product of Cd and frontal area of the vehicle) from on-road tests is presented. The possibility to measure these properties during an on-road test, without the need for a test track, enables third parties to verify the certified vehicle properties in order to preselect vehicle for further regulatory testing. On-road tests were performed with three heavy-duty vehicles, two lorries, and a coach, over different routes. Vehicles were instrumented with wheel torque sensors, wheel speed sensors, a GPS device, and a fuel flow sensor. Cd∙A of each vehicle is determined from the test data with the proposed methodology and validated against their certified value. The methodology presents satisfactory repeatability with the error ranging from −21 to 5% and averaging approximately −6.8%. A sensitivity analysis demonstrates the possibility of using the tire energy efficiency label instead of the measured RRC to determine the air drag coefficient. Finally, on-road tests were simulated in the Vehicle Energy Consumption Calculation Tool with the obtained parameters, and the average difference in fuel consumption was found to be 2%.

ACS Style

Dimitrios Komnos; Stijn Broekaert; Theodoros Grigoratos; Leonidas Ntziachristos; Georgios Fontaras. In Use Determination of Aerodynamic and Rolling Resistances of Heavy-Duty Vehicles. Sustainability 2021, 13, 974 .

AMA Style

Dimitrios Komnos, Stijn Broekaert, Theodoros Grigoratos, Leonidas Ntziachristos, Georgios Fontaras. In Use Determination of Aerodynamic and Rolling Resistances of Heavy-Duty Vehicles. Sustainability. 2021; 13 (2):974.

Chicago/Turabian Style

Dimitrios Komnos; Stijn Broekaert; Theodoros Grigoratos; Leonidas Ntziachristos; Georgios Fontaras. 2021. "In Use Determination of Aerodynamic and Rolling Resistances of Heavy-Duty Vehicles." Sustainability 13, no. 2: 974.

Research article
Published: 08 December 2020 in Environmental Science & Technology
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Shipping is the main source of anthropogenic particle emissions in large areas of the globe, influencing climate, air quality, and human health in open seas and coast lines. Here, we determined, by laboratory and on-board measurements of ship engine exhaust, fuel-specific particle number (PN) emissions for different fuels and desulfurization applied in shipping. The emission factors were compared to ship exhaust plume observations and, furthermore, exploited in the assessment of global PN emissions from shipping, utilizing the STEAM ship emission model. The results indicate that most particles in the fresh ship engine exhaust are in ultrafine particle size range. Shipping PN emissions are localized, especially close to coastal lines, but significant emissions also exist on open seas and oceans. The global annual PN produced by marine shipping was 1.2 × 1028 (±0.34 × 1028) particles in 2016, thus being of the same magnitude with total anthropogenic PN emissions in continental areas. The reduction potential of PN from shipping strongly depends on the adopted technology mix, and except wide adoption of natural gas or scrubbers, no significant decrease in global PN is expected if heavy fuel oil is mainly replaced by low sulfur residual fuels. The results imply that shipping remains as a significant source of anthropogenic PN emissions that should be considered in future climate and health impact models.

ACS Style

Niina Kuittinen; Jukka-Pekka Jalkanen; Jenni Alanen; Leonidas Ntziachristos; Hanna Hannuniemi; Lasse Johansson; Panu Karjalainen; Erkka Saukko; Mia Isotalo; Päivi Aakko-Saksa; Kati Lehtoranta; Jorma Keskinen; Pauli Simonen; Sanna Saarikoski; Eija Asmi; Tuomas Laurila; Risto Hillamo; Fanni Mylläri; Heikki Lihavainen; Hilkka Timonen; Topi Rönkkö. Shipping Remains a Globally Significant Source of Anthropogenic PN Emissions Even after 2020 Sulfur Regulation. Environmental Science & Technology 2020, 55, 129 -138.

AMA Style

Niina Kuittinen, Jukka-Pekka Jalkanen, Jenni Alanen, Leonidas Ntziachristos, Hanna Hannuniemi, Lasse Johansson, Panu Karjalainen, Erkka Saukko, Mia Isotalo, Päivi Aakko-Saksa, Kati Lehtoranta, Jorma Keskinen, Pauli Simonen, Sanna Saarikoski, Eija Asmi, Tuomas Laurila, Risto Hillamo, Fanni Mylläri, Heikki Lihavainen, Hilkka Timonen, Topi Rönkkö. Shipping Remains a Globally Significant Source of Anthropogenic PN Emissions Even after 2020 Sulfur Regulation. Environmental Science & Technology. 2020; 55 (1):129-138.

Chicago/Turabian Style

Niina Kuittinen; Jukka-Pekka Jalkanen; Jenni Alanen; Leonidas Ntziachristos; Hanna Hannuniemi; Lasse Johansson; Panu Karjalainen; Erkka Saukko; Mia Isotalo; Päivi Aakko-Saksa; Kati Lehtoranta; Jorma Keskinen; Pauli Simonen; Sanna Saarikoski; Eija Asmi; Tuomas Laurila; Risto Hillamo; Fanni Mylläri; Heikki Lihavainen; Hilkka Timonen; Topi Rönkkö. 2020. "Shipping Remains a Globally Significant Source of Anthropogenic PN Emissions Even after 2020 Sulfur Regulation." Environmental Science & Technology 55, no. 1: 129-138.

Journal article
Published: 21 October 2020 in Aerosol Science and Technology
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ACS Style

Zisimos Toumasatos; Anastasios Kontses; Stylianos Doulgeris; Zissis Samaras; Leonidas Ntziachristos. Particle emissions measurements on CNG vehicles focusing on Sub-23nm. Aerosol Science and Technology 2020, 55, 182 -193.

AMA Style

Zisimos Toumasatos, Anastasios Kontses, Stylianos Doulgeris, Zissis Samaras, Leonidas Ntziachristos. Particle emissions measurements on CNG vehicles focusing on Sub-23nm. Aerosol Science and Technology. 2020; 55 (2):182-193.

Chicago/Turabian Style

Zisimos Toumasatos; Anastasios Kontses; Stylianos Doulgeris; Zissis Samaras; Leonidas Ntziachristos. 2020. "Particle emissions measurements on CNG vehicles focusing on Sub-23nm." Aerosol Science and Technology 55, no. 2: 182-193.

Journal article
Published: 03 May 2020 in Science of The Total Environment
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This study offers emission factors for earlier and late technology medium duty diesel particulate filter (DPF) -equipped trucks, operating on real-world conditions. The analysis includes levels of nitrous oxide (N2O) emissions as well as the impacts of DPF regenerations on emission levels. The real-driving gaseous and particulate emissions, as well as fuel consumption of 14 Euro IV, Euro V, and Euro VI medium duty diesel trucks were analysed and the efficiency of different emission control technologies were assessed. Measurements were conducted using portable emission measurement systems (PEMS) over a wide range of driving and operating conditions. Distance-based integration of emission rates over 500 m sections was considered for statistical analysis, providing a large dataset of emission factors to be used for network link-based traffic and emissions modelling. In terms of emissions performance, nitrogen oxides (NOx) levels were in general above the corresponding Euro standard limits, while carbon monoxide (CO), total hydrocarbons (THC) and particulate matter (PM) levels were within limits. Selective catalytic reduction (SCR) -equipped Euro V vehicles were seen to emit more than their non-SCR-equipped counterparts. NOx and fuel consumption were positively correlated with road gradient over the −6% to 6% gradient range. The emission levels of ammonia (NH3) were measured significantly lower than the respective Euro VI provisions for heavy duty engines, while the N2O levels were found to contribute approximately 1% to the respective total greenhouse gases levels. DPF regeneration events in real world seem to have a measurable impact mostly on THC and PM emissions, increasing baseline levels by 8.1% and 29%, respectively, for Euro VI vehicles.

ACS Style

Georgios Papadopoulos; Leonidas Ntziachristos; Christos Tziourtzioumis; Christos Keramydas; Ting-Shek Lo; Kwok-Lam Ng; Hok-Lai Anson Wong; Carol Ka-Lok Wong. Real-world gaseous and particulate emissions from Euro IV to VI medium duty diesel trucks. Science of The Total Environment 2020, 731, 139137 .

AMA Style

Georgios Papadopoulos, Leonidas Ntziachristos, Christos Tziourtzioumis, Christos Keramydas, Ting-Shek Lo, Kwok-Lam Ng, Hok-Lai Anson Wong, Carol Ka-Lok Wong. Real-world gaseous and particulate emissions from Euro IV to VI medium duty diesel trucks. Science of The Total Environment. 2020; 731 ():139137.

Chicago/Turabian Style

Georgios Papadopoulos; Leonidas Ntziachristos; Christos Tziourtzioumis; Christos Keramydas; Ting-Shek Lo; Kwok-Lam Ng; Hok-Lai Anson Wong; Carol Ka-Lok Wong. 2020. "Real-world gaseous and particulate emissions from Euro IV to VI medium duty diesel trucks." Science of The Total Environment 731, no. : 139137.

Journal article
Published: 24 December 2019 in Environmental Research
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The current experimental study presents particulate emissions from 30 Euro 1-4 L-category vehicles (i.e. 2-, 3- and 4-wheelers such as mopeds, motorcycles, quads and minicars, registered in Europe between 2009 and 2016) tested on a chassis dynamometer. The objectives were to identify those sub-categories with high emissions, to assess whether the measures prescribed in the Euro 5 legislation will effectively control particulate emissions and finally to investigate the need for additional measures. The results showed that 2-stroke (2S) mopeds and diesel minicars comprised the vehicles with the highest particulate mass (PM) and solid particle number above 23 nm (SPN23) emissions (up to 64 mg/km and 4.5 × 1013 km−1, respectively). It is uncertain whether the installation of diesel particulate filters (DPF) is a cost-effective measure for diesel mini-cars in order to comply with Euro 5 standard, while advanced emission controls will be required for 2S mopeds, if such vehicles remain competitive for Euro 5. Regarding 4-stroke mopeds, motorcycles and quads, PM emissions were one order of magnitude lower than 2S ones and already below the Euro 5 limit. Nevertheless, SPN23 emissions from these sub-categories were up to 5 times higher than the Euro 6 passenger cars limit (6 × 1011 km−1). Even recent Euro 4 motorcycles exceeded this limit by up to 3 times. These results indicate that L-category vehicles are a significant contributor to vehicular particulate emissions and should be further monitored during and after the introduction of the Euro 5 step. Moreover, including SPN in the range 10–23 nm increases emission levels by up to 2.4 times compared to SPN23, while volatile and semi-volatile particle numbers were even higher. Finally, cold engine operation was found to be a significant contributor on SPN23 emissions, especially for vehicles with lower overall emission levels. These results indicate that a specific particle number limit may be required for L-category to align emissions with passenger cars.

ACS Style

A. Kontses; L. Ntziachristos; A.A. Zardini; G. Papadopoulos; B. Giechaskiel. Particulate emissions from L-Category vehicles towards Euro 5. Environmental Research 2019, 182, 109071 .

AMA Style

A. Kontses, L. Ntziachristos, A.A. Zardini, G. Papadopoulos, B. Giechaskiel. Particulate emissions from L-Category vehicles towards Euro 5. Environmental Research. 2019; 182 ():109071.

Chicago/Turabian Style

A. Kontses; L. Ntziachristos; A.A. Zardini; G. Papadopoulos; B. Giechaskiel. 2019. "Particulate emissions from L-Category vehicles towards Euro 5." Environmental Research 182, no. : 109071.

Journal article
Published: 09 November 2019 in Atmospheric Environment
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The current experimental study presents solid (non-volatile) particle number emissions with a size cut-off at 23 nm (SPN23, referred to as PN hereinafter) under real-world driving conditions for 8 passenger cars powered by diesel, gasoline, Liquefied Petroleum Gas (LPG), Compressed Natural Gas (CNG) and hybrid-electric powertrains. The objective was to identify the highest emitters and assess whether PN focus should be extended to engine and fuel types other than diesel and gasoline direct injection (GDI). Results (under the cold-start RDE-compliant route) show that a Euro 6b gasoline vehicle equipped with port fuel injection (PFI) engine, comprised the highest PN emitter (4.5 times higher than the Euro 6 limit of 6 × 1011 p/km), while similar emission levels (up to 3.7 times higher than this limit) were detected in the older-technology (Euro 3 and 4) gasoline and (retrofitted) LPG PFI vehicles. This limit was also exceeded (by 1.7 times) by one gasoline direct injection (GDI) Euro 6b non-GPF vehicle. PN emissions from the hybrid-electric vehicle (equipped with gasoline PFI engine) were lower than the other Euro 6b PFI vehicle, but still high compared to typical PFI engines found in literature. The lowest emissions were detected in diesel and CNG engines (as low as 7.8 × 109 and 2.4 × 1010 p/km respectively). Euro 6b LPG vehicle was found to be a low emitter (3.3 times lower than the 6 × 1011 p/km limit), while similar emission levels were detected in the other Euro 6b non-GPF GDI vehicle. Among the different driving sections (urban, rural, motorway), urban and especially the cold phase had the highest contribution in most cases. Finally, a significant PN reduction potential was observed with LPG and CNG over gasoline (up to 93% and 90% respectively), although the opposite trend was detected in an old-technology retrofitted LPG vehicle. These results indicate that close attention should be focused on other engine and fuel types, apart from diesel and GDI. Regulatory initiatives towards air pollution reduction should include measures for the reduction of high-emission old-technology gasoline and LPG vehicles, while modern gasoline PFI engines should also be further scrutinized.

ACS Style

A. Kontses; G. Triantafyllopoulos; L. Ntziachristos; Z. Samaras. Particle number (PN) emissions from gasoline, diesel, LPG, CNG and hybrid-electric light-duty vehicles under real-world driving conditions. Atmospheric Environment 2019, 222, 117126 .

AMA Style

A. Kontses, G. Triantafyllopoulos, L. Ntziachristos, Z. Samaras. Particle number (PN) emissions from gasoline, diesel, LPG, CNG and hybrid-electric light-duty vehicles under real-world driving conditions. Atmospheric Environment. 2019; 222 ():117126.

Chicago/Turabian Style

A. Kontses; G. Triantafyllopoulos; L. Ntziachristos; Z. Samaras. 2019. "Particle number (PN) emissions from gasoline, diesel, LPG, CNG and hybrid-electric light-duty vehicles under real-world driving conditions." Atmospheric Environment 222, no. : 117126.

Journal article
Published: 09 October 2019 in Environmental Science & Technology
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ACS Style

Hilkka Timonen; Panu Karjalainen; Pami Aalto; Sanna Saarikoski; Fanni Mylläri; Niko Karvosenoja; Pasi Jalava; Eija Asmi; Päivi Aakko-Saksa; Natalia Saukkonen; Teemu Laine; Karri Saarnio; Niko Niemelä; Joonas Enroth; Minna Väkevä; Pedro Oyola; Joakim Pagels; Leonidas Ntziachristos; Raul Cordero; Niina Kuittinen; Jarkko Niemi; Topi Rönkkö. Adaptation of Black Carbon Footprint Concept Would Accelerate Mitigation of Global Warming. Environmental Science & Technology 2019, 53, 12153 -12155.

AMA Style

Hilkka Timonen, Panu Karjalainen, Pami Aalto, Sanna Saarikoski, Fanni Mylläri, Niko Karvosenoja, Pasi Jalava, Eija Asmi, Päivi Aakko-Saksa, Natalia Saukkonen, Teemu Laine, Karri Saarnio, Niko Niemelä, Joonas Enroth, Minna Väkevä, Pedro Oyola, Joakim Pagels, Leonidas Ntziachristos, Raul Cordero, Niina Kuittinen, Jarkko Niemi, Topi Rönkkö. Adaptation of Black Carbon Footprint Concept Would Accelerate Mitigation of Global Warming. Environmental Science & Technology. 2019; 53 (21):12153-12155.

Chicago/Turabian Style

Hilkka Timonen; Panu Karjalainen; Pami Aalto; Sanna Saarikoski; Fanni Mylläri; Niko Karvosenoja; Pasi Jalava; Eija Asmi; Päivi Aakko-Saksa; Natalia Saukkonen; Teemu Laine; Karri Saarnio; Niko Niemelä; Joonas Enroth; Minna Väkevä; Pedro Oyola; Joakim Pagels; Leonidas Ntziachristos; Raul Cordero; Niina Kuittinen; Jarkko Niemi; Topi Rönkkö. 2019. "Adaptation of Black Carbon Footprint Concept Would Accelerate Mitigation of Global Warming." Environmental Science & Technology 53, no. 21: 12153-12155.

Journal article
Published: 12 September 2019 in Environmental Pollution
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Emissions from passenger cars are one of major sources that deteriorate urban air quality. This study presents characterization of real-drive emissions from three Euro 6 emission level passenger cars (two gasoline and one diesel) in terms of fresh particles and secondary aerosol formation. The gasoline vehicles were also characterized by chassis dynamometer studies. In the real-drive study, the particle number emissions during regular driving were 1.1–12.7 times greater than observed in the laboratory tests (4.8 times greater on average), which may be caused by more effective nucleation process when diluted by real polluted and humid ambient air. However, the emission factors measured in laboratory were still much higher than the regulatory value of 6 × 1011 particles km−1. The higher emission factors measured here result probably from the fact that the regulatory limit considers only non-volatile particles larger than 23 nm, whereas here, all particles (also volatile) larger than 3 nm were measured. Secondary aerosol formation potential was the highest after a vehicle cold start when most of the secondary mass was organics. After the cold start, the relative contributions of ammonium, sulfate and nitrate increased. Using a novel approach to study secondary aerosol formation under real-drive conditions with the chase method resulted mostly in emission factors below detection limit, which was not in disagreement with the laboratory findings.

ACS Style

Pauli Simonen; Joni Kalliokoski; Panu Karjalainen; Topi Rönkkö; Hilkka Timonen; Sanna Saarikoski; Minna Aurela; Matthew Bloss; Georgios Triantafyllopoulos; Anastasios Kontses; Stavros Amanatidis; Athanasios Dimaratos; Zissis Samaras; Jorma Keskinen; Miikka Dal Maso; Leonidas Ntziachristos. Characterization of laboratory and real driving emissions of individual Euro 6 light-duty vehicles – Fresh particles and secondary aerosol formation. Environmental Pollution 2019, 255, 113175 .

AMA Style

Pauli Simonen, Joni Kalliokoski, Panu Karjalainen, Topi Rönkkö, Hilkka Timonen, Sanna Saarikoski, Minna Aurela, Matthew Bloss, Georgios Triantafyllopoulos, Anastasios Kontses, Stavros Amanatidis, Athanasios Dimaratos, Zissis Samaras, Jorma Keskinen, Miikka Dal Maso, Leonidas Ntziachristos. Characterization of laboratory and real driving emissions of individual Euro 6 light-duty vehicles – Fresh particles and secondary aerosol formation. Environmental Pollution. 2019; 255 ():113175.

Chicago/Turabian Style

Pauli Simonen; Joni Kalliokoski; Panu Karjalainen; Topi Rönkkö; Hilkka Timonen; Sanna Saarikoski; Minna Aurela; Matthew Bloss; Georgios Triantafyllopoulos; Anastasios Kontses; Stavros Amanatidis; Athanasios Dimaratos; Zissis Samaras; Jorma Keskinen; Miikka Dal Maso; Leonidas Ntziachristos. 2019. "Characterization of laboratory and real driving emissions of individual Euro 6 light-duty vehicles – Fresh particles and secondary aerosol formation." Environmental Pollution 255, no. : 113175.

Journal article
Published: 10 September 2019 in Atmosphere
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Heavy-duty diesel trucks (HDDTs) comprise a key source of road transport emissions and energy consumption worldwide mainly due to the growth of road freight traffic during the last two decades. Addressing their air pollutant and greenhouse gas emissions is therefore required, while accurate emission factors are needed to logistically optimize their operation. This study characterizes real-world emissions and fuel consumption (FC) of HDDTs and investigates the factors that affect their performance. Twenty-two diesel-fueled, Euro IV to Euro VI, HDDTs of six different manufacturers were measured in the road network of the Hong Kong metropolitan area, using portable emission measurement systems (PEMS). The testing routes included urban, highway and mixed urban/highway driving. The data collected corresponds to a wide range of driving, operating, and ambient conditions. Real-world distance- and energy-based emission levels are presented in a comparative manner to capture the effect of after-treatment technologies and the role of the evolution of Euro standards on emissions performance. The emission factors’ uncertainty is analyzed. The impact of speed, road grade and vehicle weight loading on FC and emissions is investigated. An analysis of diesel particulate filter (DPF) regenerations and ammonia (NH3) slip events are presented along with the study of Nitrous oxide (N2O) formation. The results reveal deviations of real-world HDDTs emissions from emission limits, as well as the significant impact of different operating and driving factors on their performance. The occasional high levels of N2O emissions from selective catalytic reduction equipped HDDTs is also revealed, an issue that has not been thoroughly considered so far.

ACS Style

Christos Keramydas; Leonidas Ntziachristos; Christos Tziourtzioumis; Georgios Papadopoulos; Ting-Shek Lo; Kwok-Lam Ng; Hok-Lai Anson Wong; Carol Ka-Lok Wong. Characterization of Real-World Pollutant Emissions and Fuel Consumption of Heavy-Duty Diesel Trucks with Latest Emissions Control. Atmosphere 2019, 10, 535 .

AMA Style

Christos Keramydas, Leonidas Ntziachristos, Christos Tziourtzioumis, Georgios Papadopoulos, Ting-Shek Lo, Kwok-Lam Ng, Hok-Lai Anson Wong, Carol Ka-Lok Wong. Characterization of Real-World Pollutant Emissions and Fuel Consumption of Heavy-Duty Diesel Trucks with Latest Emissions Control. Atmosphere. 2019; 10 (9):535.

Chicago/Turabian Style

Christos Keramydas; Leonidas Ntziachristos; Christos Tziourtzioumis; Georgios Papadopoulos; Ting-Shek Lo; Kwok-Lam Ng; Hok-Lai Anson Wong; Carol Ka-Lok Wong. 2019. "Characterization of Real-World Pollutant Emissions and Fuel Consumption of Heavy-Duty Diesel Trucks with Latest Emissions Control." Atmosphere 10, no. 9: 535.

Journal article
Published: 06 September 2019 in Transportation Research Part D: Transport and Environment
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This study aims to demonstrate a new approach for estimating fuel consumption from vehicles circulating on urban roads with different levels of congestion. A microscopic dynamic traffic model (AIMSUN) was coupled with an instantaneous emissions model (CRUISE) and their output was used to refine the average speed model (COPERT) functions. The integrated methodology was applied in an urban corridor in Turin using two validated vehicle models of Euro 5 passenger cars. Three traffic conditions were examined, corresponding to free-flow, normal and congested traffic. New average speed – fuel consumption functions were developed for free and congested traffic, which successfully estimated the differences in fuel consumption when moving from normal to other conditions. The results showed that under congested conditions the fuel consumption can increase by more than 18% in some cases, indicating the significance of incorporating similar congestion algorithms in macro emission models. Moreover, if a more comprehensive method does not exist, the standard COPERT functions could be used to estimate fuel consumption under congested traffic conditions.

ACS Style

Christos Samaras; Dimitrios Tsokolis; Silvana Toffolo; Giorgio Magra; Leonidas Ntziachristos; Zissis Samaras. Enhancing average speed emission models to account for congestion impacts in traffic network link-based simulations. Transportation Research Part D: Transport and Environment 2019, 75, 197 -210.

AMA Style

Christos Samaras, Dimitrios Tsokolis, Silvana Toffolo, Giorgio Magra, Leonidas Ntziachristos, Zissis Samaras. Enhancing average speed emission models to account for congestion impacts in traffic network link-based simulations. Transportation Research Part D: Transport and Environment. 2019; 75 ():197-210.

Chicago/Turabian Style

Christos Samaras; Dimitrios Tsokolis; Silvana Toffolo; Giorgio Magra; Leonidas Ntziachristos; Zissis Samaras. 2019. "Enhancing average speed emission models to account for congestion impacts in traffic network link-based simulations." Transportation Research Part D: Transport and Environment 75, no. : 197-210.

Journal article
Published: 13 August 2019 in Environmental Science & Technology
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Particle emissions and secondary aerosol formation from internal combustion engines deteriorate air quality and significantly affect human wellbeing and health. Both the direct particle emissions and the emissions of compounds contributing to secondary aerosol formation depend on choices made in selecting fuels, engine technologies, and exhaust aftertreatment (EAT). Here we study how catalytic EATs, particle filtration, and fuel choices affect these emissions concerning heavy-duty diesel engine. We observed that the most advanced EAT decreased the emissions of fresh exhaust particle mass as much as 98% (from 44.7 to 0.73 mg/kWh) and the formation of aged exhaust particle mass ∼100% (from 106.2 to ∼0 mg/kWh). The composition of emitted particles depended significantly on the EAT and oxidative aging. While black carbon typically dominated the composition of fresh exhaust particles, aged particles contained more sulfates and organics. The fuel choices had minor effects on the secondary aerosol formation, implicating that, in diesel engines, either the lubricant is a significant source of secondary aerosol precursors or the precursors are formed in the combustion process. Results indicate that the utilization of EAT in diesel engines would produce benefits with respect to exhaust burden on air quality, and thus their utilization should be promoted especially in geographical areas suffering from poor air quality.

ACS Style

Panu Karjalainen; Topi Rönkkö; Pauli Simonen; Leonidas Ntziachristos; Paxton Juuti; Hilkka Timonen; Kimmo Teinilä; Sanna Saarikoski; Henna Saveljeff; Mika Lauren; Matti Happonen; Pekka Matilainen; Teuvo Maunula; Jukka Nuottimäki; Jorma Keskinen. Strategies To Diminish the Emissions of Particles and Secondary Aerosol Formation from Diesel Engines. Environmental Science & Technology 2019, 53, 10408 -10416.

AMA Style

Panu Karjalainen, Topi Rönkkö, Pauli Simonen, Leonidas Ntziachristos, Paxton Juuti, Hilkka Timonen, Kimmo Teinilä, Sanna Saarikoski, Henna Saveljeff, Mika Lauren, Matti Happonen, Pekka Matilainen, Teuvo Maunula, Jukka Nuottimäki, Jorma Keskinen. Strategies To Diminish the Emissions of Particles and Secondary Aerosol Formation from Diesel Engines. Environmental Science & Technology. 2019; 53 (17):10408-10416.

Chicago/Turabian Style

Panu Karjalainen; Topi Rönkkö; Pauli Simonen; Leonidas Ntziachristos; Paxton Juuti; Hilkka Timonen; Kimmo Teinilä; Sanna Saarikoski; Henna Saveljeff; Mika Lauren; Matti Happonen; Pekka Matilainen; Teuvo Maunula; Jukka Nuottimäki; Jorma Keskinen. 2019. "Strategies To Diminish the Emissions of Particles and Secondary Aerosol Formation from Diesel Engines." Environmental Science & Technology 53, no. 17: 10408-10416.

Journal article
Published: 21 July 2019 in Atmosphere
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The scientific literature indicates that solid particle number (SPN) emissions of motorcycles are usually higher than that of passenger cars. The L-category (e.g., mopeds, motorcycles) Euro 4 and 5 environmental steps were designed to reduce the emissions of particulate matter and ozone precursors such as nitrogen oxides and hydrocarbons. In this study the SPN emissions of one moped and eight motorcycles, all fulfilling the Euro 4 standards, were measured with a SPN measurement system employing a catalytic stripper to minimize volatile artefacts. Although the particulate matter mass emissions were

ACS Style

Barouch Giechaskiel; Alessandro A. Zardini; Tero Lähde; Adolfo Perujo; Anastasios Kontses; Leonidas Ntziachristos. Particulate Emissions of Euro 4 Motorcycles and Sampling Considerations. Atmosphere 2019, 10, 421 .

AMA Style

Barouch Giechaskiel, Alessandro A. Zardini, Tero Lähde, Adolfo Perujo, Anastasios Kontses, Leonidas Ntziachristos. Particulate Emissions of Euro 4 Motorcycles and Sampling Considerations. Atmosphere. 2019; 10 (7):421.

Chicago/Turabian Style

Barouch Giechaskiel; Alessandro A. Zardini; Tero Lähde; Adolfo Perujo; Anastasios Kontses; Leonidas Ntziachristos. 2019. "Particulate Emissions of Euro 4 Motorcycles and Sampling Considerations." Atmosphere 10, no. 7: 421.

Review
Published: 04 July 2019 in Catalysts
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The particulate matter (PM) emissions of gasoline vehicles were much lower than those of diesel vehicles until the introduction of diesel particulate filters (DPFs) in the early 2000s. At the same time, gasoline direct injection (GDI) engines started to become popular in the market due to their improved efficiency over port fuel injection (PFI) ones. However, the PM mass and number emissions of GDI vehicles were higher than their PFI counterparts and diesel ones equipped with DPFs. Stringent PM mass levels and the introduction of particle number limits for GDI vehicles in the European Union (EU) resulted in significant PM reductions. The EU requirement to fulfill the proposed limits on the road resulted to the introduction of gasoline particulate filters (GPFs) in EU GDI models. This review summarizes the evolution of PM mass emissions from gasoline vehicles placed in the market from early 1990s until 2019 in different parts of the world. The analysis then extends to total and nonvolatile particle number emissions. Care is given to reveal the impact of ambient temperature on emission levels. The discussion tries to provide scientific input to the following policy-relevant questions. Whether particle number limits should be extended to gasoline PFI vehicles, whether the lower limit of 23 nm for particle number measurements should be decreased to 10 nm, and whether low ambient temperature tests for PM should be included.

ACS Style

Barouch Giechaskiel; Ameya Joshi; Leonidas Ntziachristos; Panagiota Dilara. European Regulatory Framework and Particulate Matter Emissions of Gasoline Light-Duty Vehicles: A Review. Catalysts 2019, 9, 586 .

AMA Style

Barouch Giechaskiel, Ameya Joshi, Leonidas Ntziachristos, Panagiota Dilara. European Regulatory Framework and Particulate Matter Emissions of Gasoline Light-Duty Vehicles: A Review. Catalysts. 2019; 9 (7):586.

Chicago/Turabian Style

Barouch Giechaskiel; Ameya Joshi; Leonidas Ntziachristos; Panagiota Dilara. 2019. "European Regulatory Framework and Particulate Matter Emissions of Gasoline Light-Duty Vehicles: A Review." Catalysts 9, no. 7: 586.

Journal article
Published: 15 March 2019 in Environmental Science & Technology
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This study reports on the results of gaseous pollutants emission measurements of double-decker buses in an urban road network, using portable emission measurement systems (PEMS). Measured vehicles were tested by following in-service buses on regular routes. Six Euro II and Euro III buses were retrofitted with diesel particulate filters (DPF) and selective catalytic reduction (SCR), or a combined SCR+DPF (SCRT) device. Substantial and statistically significant technology impacts were observed for several pollutants. Optimized SCR and SCRT retrofit technology reduced real-world NOx emissions by approximately 70%, on average. Retrofit DPF slightly reduced NOx emissions, but increased direct NO2 emissions by more than a factor of 8, on average. SCRT led to about 70% lower NO2 levels than DPF alone, but for some vehicles higher NO2 levels were observed as compared with the ‘no retrofit’ situation, warranting further investigation. None of the SCR systems were found to lead to a substantial increase in NH3 emissions after operation optimization. High NH3 and N2O emissions were occasionally observed, while experience with the system calibration was being accumulated. Observed average N2O emission levels for ‘DPF+SCR’ technology were relatively high at 182 mg/kg fuel, corresponding to 1.5% of total greenhouse gas emissions. The study shows that SCR retrofit programs can be effective for NOx reduction of transit buses, but that proper calibration and regular emission monitoring are required.

ACS Style

Robin Smit; Christos Keramydas; Leonidas Ntziachristos; Ting-Shek Lo; Kwok-Lam Ng; Hok-Lai Anson Wong; Carol Ka-Lok Wong. Evaluation of Real-World Gaseous Emissions Performance of Selective Catalytic Reduction and Diesel Particulate Filter Bus Retrofits. Environmental Science & Technology 2019, 53, 4440 -4449.

AMA Style

Robin Smit, Christos Keramydas, Leonidas Ntziachristos, Ting-Shek Lo, Kwok-Lam Ng, Hok-Lai Anson Wong, Carol Ka-Lok Wong. Evaluation of Real-World Gaseous Emissions Performance of Selective Catalytic Reduction and Diesel Particulate Filter Bus Retrofits. Environmental Science & Technology. 2019; 53 (8):4440-4449.

Chicago/Turabian Style

Robin Smit; Christos Keramydas; Leonidas Ntziachristos; Ting-Shek Lo; Kwok-Lam Ng; Hok-Lai Anson Wong; Carol Ka-Lok Wong. 2019. "Evaluation of Real-World Gaseous Emissions Performance of Selective Catalytic Reduction and Diesel Particulate Filter Bus Retrofits." Environmental Science & Technology 53, no. 8: 4440-4449.

Research article
Published: 19 February 2019 in Environmental Science & Technology
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In order to meet stringent fuel sulfur limits, ships are increasingly utilizing new fuels or, alternatively, scrubbers to reduce sulfur emissions from the combustion of sulfur-rich heavy fuel oil. The effects of these methods on particle emissions are important, since particle emissions from shipping traffic are known to have both climatic and health effects. In this study, the effects of lower sulfur level liquid fuels, natural gas (NG), and exhaust scrubbers on particulate mass (PM) and non-volatile particle number (PN greater than 23 nm) emissions were studied by measurements in laboratory tests and in-use. The fuel change to lower sulfur level fuels or to NG and the use of scrubbers significantly decreased the PM emissions. However, this was not directly linked with non-volatile PN emission reduction, which should be taken into consideration when discussing the health effects of emitted particles. The lowest PM and PN emissions were measured when utilizing NG as fuel, indicating that the use of NG could be one way to comply with up-coming regulations for inland waterway vessels. Low PN levels were associated with low elemental carbon. However, a simultaneously observed methane slip should be taken into consideration when evaluating the climatic impacts of NG-fueled engines.

ACS Style

Kati Lehtoranta; Päivi Aakko-Saksa; Timo Murtonen; Hannu Vesala; Leonidas Ntziachristos; Topi Rönkkö; Panu Karjalainen; Niina Kuittinen; Hilkka Timonen. Particulate Mass and Nonvolatile Particle Number Emissions from Marine Engines Using Low-Sulfur Fuels, Natural Gas, or Scrubbers. Environmental Science & Technology 2019, 53, 3315 -3322.

AMA Style

Kati Lehtoranta, Päivi Aakko-Saksa, Timo Murtonen, Hannu Vesala, Leonidas Ntziachristos, Topi Rönkkö, Panu Karjalainen, Niina Kuittinen, Hilkka Timonen. Particulate Mass and Nonvolatile Particle Number Emissions from Marine Engines Using Low-Sulfur Fuels, Natural Gas, or Scrubbers. Environmental Science & Technology. 2019; 53 (6):3315-3322.

Chicago/Turabian Style

Kati Lehtoranta; Päivi Aakko-Saksa; Timo Murtonen; Hannu Vesala; Leonidas Ntziachristos; Topi Rönkkö; Panu Karjalainen; Niina Kuittinen; Hilkka Timonen. 2019. "Particulate Mass and Nonvolatile Particle Number Emissions from Marine Engines Using Low-Sulfur Fuels, Natural Gas, or Scrubbers." Environmental Science & Technology 53, no. 6: 3315-3322.

Journal article
Published: 11 February 2019 in Science of The Total Environment
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The current study presents a detailed analysis of the gaseous emissions, focusing on CO2 and NOx, of diesel vehicles under several operating conditions. An assessment is also made on the impact and effectiveness of the Real Driving Emissions (RDE) test, which is mandatory by the European Union (EU) type approval regulation for passenger cars since September 2017. The method followed comprises emissions measurement tests on three Euro 6 diesel vehicles, under laboratory and various on-road operation conditions. Chassis dynamometer tests in the laboratory showed that emissions over the current type approval test (World-wide harmonized Light-duty Test Procedure or WLTP), and over the former one (New European Driving Cycle or NEDC), poorly reflect real-world levels. However, the most demanding CADC testing comes closer to real drive emissions. Comparison of driving conditions on the chassis dynamometer over different driving cycles and on the road reveals that the emission performance substantially varies between different tests, even for apparently similar operation conditions. The NOx emissions reduction strategy of pre-RDE monitoring Euro 6 vehicles seems to be optimized for the NEDC driving conditions, which are not representative of the real-world driving conditions. The real-world emissions during normal driving conditions are effectively captured with the new RDE test, however driving the vehicle dynamically, at conditions outside the RDE regulation boundaries, results to disproportional high emissions. This is a significant shortcoming which might be critical for populations living on hilly areas or those close to specific micro-environments, such as highway entrance ramps, traffic lights, etc.

ACS Style

Georgios Triantafyllopoulos; Athanasios Dimaratos; Leonidas Ntziachristos; Yoann Bernard; Jan Dornoff; Zissis Samaras. A study on the CO2 and NOx emissions performance of Euro 6 diesel vehicles under various chassis dynamometer and on-road conditions including latest regulatory provisions. Science of The Total Environment 2019, 666, 337 -346.

AMA Style

Georgios Triantafyllopoulos, Athanasios Dimaratos, Leonidas Ntziachristos, Yoann Bernard, Jan Dornoff, Zissis Samaras. A study on the CO2 and NOx emissions performance of Euro 6 diesel vehicles under various chassis dynamometer and on-road conditions including latest regulatory provisions. Science of The Total Environment. 2019; 666 ():337-346.

Chicago/Turabian Style

Georgios Triantafyllopoulos; Athanasios Dimaratos; Leonidas Ntziachristos; Yoann Bernard; Jan Dornoff; Zissis Samaras. 2019. "A study on the CO2 and NOx emissions performance of Euro 6 diesel vehicles under various chassis dynamometer and on-road conditions including latest regulatory provisions." Science of The Total Environment 666, no. : 337-346.

Journal article
Published: 01 December 2018 in Transportation Research Part D: Transport and Environment
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ACS Style

Christos Samaras; Dimitris Tsokolis; Silvana Toffolo; Giorgio Magra; Leonidas Ntziachristos; Zissis Samaras. Improving fuel consumption and CO2 emissions calculations in urban areas by coupling a dynamic micro traffic model with an instantaneous emissions model. Transportation Research Part D: Transport and Environment 2018, 65, 772 -783.

AMA Style

Christos Samaras, Dimitris Tsokolis, Silvana Toffolo, Giorgio Magra, Leonidas Ntziachristos, Zissis Samaras. Improving fuel consumption and CO2 emissions calculations in urban areas by coupling a dynamic micro traffic model with an instantaneous emissions model. Transportation Research Part D: Transport and Environment. 2018; 65 ():772-783.

Chicago/Turabian Style

Christos Samaras; Dimitris Tsokolis; Silvana Toffolo; Giorgio Magra; Leonidas Ntziachristos; Zissis Samaras. 2018. "Improving fuel consumption and CO2 emissions calculations in urban areas by coupling a dynamic micro traffic model with an instantaneous emissions model." Transportation Research Part D: Transport and Environment 65, no. : 772-783.

Journal article
Published: 26 September 2018 in Energies
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This study investigates pollutant emissions and fuel consumption of six Euro VI hybrid-diesel public transport buses operating on different scheduled routes in a metropolitan urban road network. Portable emission measurement systems (PEMS) are used in measurements and results are compared to those obtained from a paired number of Euro V conventional buses of the same body type used as control over the same routes. The selected routes vary from urban to highway driving and the experimentation was conducted over the first half of 2015. The available emissions data correspond to a wide range of driving, operating, and ambient conditions. Fuel consumption, distance- and energy-based emission levels are derived and presented in a comparative manner. The effect of different factors, including speed, ambient temperature, and road grade on fuel consumption and emissions performance is investigated. Mean fuel consumption of hybrid buses was found 6.1% lower than conventional ones, from 20% lower up to 16% higher, over six routes tested in total. The mean route difference between the two technologies was not statistically significant. Air conditioning decreased consumption benefits of the hybrid buses. Decrease of the mean route speed from 15 km h−1 tο 8 km h−1 increased the hybrid buses consumption by 63%. Nitrogen oxides (NOx) emissions of the Euro VI hybrid buses were 93 ± 5% lower than conventional Euro V ones. Nitrous oxide (N2O) emissions from hybrid Euro VI buses made up 5.9% of total greenhouse gas emissions and largely offset carbon dioxide (CO2) benefits. The results suggest that hybrid urban buses need to be assessed under realistic operation and environmental conditions to assess their true environmental and fuel consumption benefits.

ACS Style

Christos Keramydas; Georgios Papadopoulos; Leonidas Ntziachristos; Ting-Shek Lo; Kwok-Lam Ng; Hok-Lai Anson Wong; Carol Ka-Lok Wong. Real-World Measurement of Hybrid Buses’ Fuel Consumption and Pollutant Emissions in a Metropolitan Urban Road Network. Energies 2018, 11, 2569 .

AMA Style

Christos Keramydas, Georgios Papadopoulos, Leonidas Ntziachristos, Ting-Shek Lo, Kwok-Lam Ng, Hok-Lai Anson Wong, Carol Ka-Lok Wong. Real-World Measurement of Hybrid Buses’ Fuel Consumption and Pollutant Emissions in a Metropolitan Urban Road Network. Energies. 2018; 11 (10):2569.

Chicago/Turabian Style

Christos Keramydas; Georgios Papadopoulos; Leonidas Ntziachristos; Ting-Shek Lo; Kwok-Lam Ng; Hok-Lai Anson Wong; Carol Ka-Lok Wong. 2018. "Real-World Measurement of Hybrid Buses’ Fuel Consumption and Pollutant Emissions in a Metropolitan Urban Road Network." Energies 11, no. 10: 2569.

Proceedings article
Published: 30 May 2018 in SAE Technical Paper Series
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With the adoption of the Worldwide harmonized Light Vehicles Test Procedure (WLTP) and the Real Driving Emissions (RDE) regulations for testing and monitoring the vehicle pollutant emissions, as well as CO2 and fuel consumption, the gap between real world and type approval performances is expected to decrease to a large extent. With respect to CO2, however, WLTP is not expected to fully eliminate the reported 40% discrepancy between real world and type approval values. This is mainly attributed to the fact that laboratory tests take place under average controlled conditions that do not fully replicate the environmental and traffic conditions experienced over daily driving across Europe. In addition, any uncertainties of a pre-defined test protocol and the vehicle operation can be optimized to lower the CO2 emissions of the type approval test.Such issues can be minimized in principle with the adoption of a real-world test for fuel consumption. However, repeatability and an accuracy of a few gCO2/km is difficult to achieve due to the actual drag, the road surface effect on driving resistance, the road slope, the battery and auxiliaries use etc., which come naturally with on-road tests. Since a reference value for CO2 emissions should not depend on the testing circumstances, modeling can be deployed in order to introduce the necessary correction of measurement variations in a harmonized manner, based on individual vehicle simulation models that can produce smoothed results under the same driving conditions, ambient temperature, alternator operation etc. In this paper, such a simulation approach for the correction of RDE compliant measurements is introduced and demonstrated with a few real cases. The approach incorporates the encountered real-world effects for the prediction of a reference CO2 value. It is shown that with an expansion of the approach to cover variations for existing engine types, powertrains, vehicle types etc., baseline accuracy for real world simulations can be established.

ACS Style

Zissis Samaras; Dimitris Tsokolis; Athanasios Dimaratos; Leonidas Ntziachristos; Stylianos Doulgeris; Norbert Ligterink; Willar Vonk; Rob Cuelenaere. A Model Based Definition of a Reference CO2 Emissions Value for Passenger Cars under Real World Conditions. SAE Technical Paper Series 2018, 1 .

AMA Style

Zissis Samaras, Dimitris Tsokolis, Athanasios Dimaratos, Leonidas Ntziachristos, Stylianos Doulgeris, Norbert Ligterink, Willar Vonk, Rob Cuelenaere. A Model Based Definition of a Reference CO2 Emissions Value for Passenger Cars under Real World Conditions. SAE Technical Paper Series. 2018; ():1.

Chicago/Turabian Style

Zissis Samaras; Dimitris Tsokolis; Athanasios Dimaratos; Leonidas Ntziachristos; Stylianos Doulgeris; Norbert Ligterink; Willar Vonk; Rob Cuelenaere. 2018. "A Model Based Definition of a Reference CO2 Emissions Value for Passenger Cars under Real World Conditions." SAE Technical Paper Series , no. : 1.