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| 2. |
- Liu, Qianyun, et al.
(author)
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Roadside assessment of a modern city bus fleet: Gaseous and particle emissions
- 2019
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In: Atmospheric Environment: X. - : Elsevier BV. - 2590-1621. ; 3
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Journal article (peer-reviewed)abstract
- © 2019 The Authors In many cities worldwide, modern fleets have been introduced to reduce gaseous and particle emissions from city buses. To date, most emission studies are limited to a few vehicles, making a statistically significant assessment of control options difficult, especially under real-world driving conditions. Exhaust emissions of 234 individual city buses were measured under real-world stop-and-go traffic conditions at a bus stop in Gothenburg, Sweden. The buses comprised models fulfilling Euro III-VI and EEV (Enhanced Environmentally Friendly Vehicle) standards with different engine technologies, fuels, and exhaust after-treatment systems, and also included hybrid-electric buses (HEV). Both gaseous (NOx, CO, HC, and SO2) and size-resolved particle number (PN) and mass (PM) emission factors (EF) were calculated for vehicles using compressed natural gas (CNG), diesel (DSL), Rapeseed Methyl Ester (RME) and Hydro-treated Vegetable Oil (HVO) equipped with various after-treatment technologies, e.g., diesel particulate filter (DPF), selective catalytic reduction (SCR) and exhaust gas recirculation (EGR) systems. The highest median EFPN was obtained from Euro VHEV-HVO-SCR buses (MdEFPN = 18×1014 # kg-1) when their combustion engines were used though 53% of their accelerations were below detection limits indicating the use of their electrical engine. The highest MdEFPM was obtained from the Euro V-DSL-SCR buses (MdEFPM = 150 mg kg-1) and the lowest from EEV-CNG buses (below detection threshold) and Euro VIHEV-HVO- SCR+EGR+DPF buses (MdEFPM = 19 mg kg-1). The highest MdEFNOx was obtained from the Euro V-RME-SCR (MdEFNOx = 30 g kg-1) and Euro VHEV-HVO-SCR buses (MdEFNOx = 24 g kg-1), and the lowest from CNG buses (MdEFNOx = 4.8 g kg-1) and Euro VIHEV-HVO-SCR+EGR+DPF buses (MdEFNOx = 7.4 g kg-1). Hybrid buses can give higher PN emissions compared to traditional diesel engines, likely due to downsized combustion engines. Replacing diesel by biodiesel fuel reduced MdEFPM significantly but increased MdEFNOx which may be due to the higher combustion temperature and oxygen contents of the fuel (for RME). Overall, the EEV-CNG buses performed the best regarding both the MdEF and low contribution to the high emitters. It was also found that a small (5%) proportion of the buses contributed significantly (14-30%) to the total emissions. Identification and monitoring the maintenance of the high emitters in the fleets should be considered for the improvement of air quality.
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| 3. |
- Wen, Qianyun, 1993-
(author)
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Decision Support for Energy Transition : Application of Multi-criteria Decision Making on Danish Residential Heating
- 2023
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Licentiate thesis (other academic/artistic)abstract
- With the increasing awareness of the impact of climate change, there has been more intention to reduce greenhouse gas emissions and achieve carbon neutrality targets. However, as one essential element for human well-being, residential heating remains a major contributor to global greenhouse gas emissions. The complex, interdependent, and sometimes contradictory nature of factors influencing residential heating choices makes it a difficult problem to address. Multiple actors with different goals and priorities further complicate the decision-making process. Moreover, given the current energy crisis, selecting an appropriate heating system for residential areas has become even more crucial. Therefore, there is a need for decision support tools that can consider multi-dimensional factors and heating alternatives, which usually have a long-term impact involved in residential heating choices. Thus, this thesis aims to improve the understanding of what influences decisions to choose a heating technology alternative and how decision support tools can sup-port these decisions. Among the decision-making techniques, multi-criteria decision-making (MCDM) methods have been chosen because they are capable of considering a wide range of factors and are simple to understand and use, taking into account data availability and capability. A systematic literature review is conducted to understand the criteria and MCDM methods commonly used in the field. Two appended papers applied different approaches of MCDM methods to support the Danish residential heating transition. These applications also act as case studies to address the research questions. This thesis highlights financial, technical, and environmental factors for decision-making on heating technologies and addresses common problems that might occur during the decision-support process. Specifically, it suggests considering financial costs, environmental emissions, technical efficiency and lifetime when choosing a heating technology and using distance-to-ideal MCDM combining other methods. Furthermore, the thesis reflects on the complexity of MCDM applications in decision support and presents a publicly available online decision support tool based on the research (https://api.flexsus.org/MCDM). This thesis contributes to knowledge for academics and fills gaps in residential heating decision-making. For practitioners, a useful tool is provided for improving the quality of decision-making in residential heating, offering a practical and scientific perspective for making informed decisions without consuming extra resources. By increasing the under-standing of influencing factors and decision-support methods for heating technologies, this thesis helps facilitate the heating transition.
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| 4. |
- Kao, Xiaoxuan, et al.
(author)
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The pressure of coal consumption on China's carbon dioxide emissions: A spatial and temporal perspective
- 2024
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In: Atmospheric Pollution Research. - : TURKISH NATL COMMITTEE AIR POLLUTION RES & CONTROL-TUNCAP. - 1309-1042. ; 15:8
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Journal article (peer-reviewed)abstract
- As the world's largest coal consumer, China is facing the dual challenge of implementing strict coal reduction policies while heavily relying on coal. It is crucial to comprehend the pressures exerted on carbon dioxide emissions from coal consumption as China strives to transition towards a carbon-neutral era. This study defines and classifies the pressure of carbon dioxide emissions resulting from coal consumption, referred to as "carboncoal pressure", in 30 provinces (including municipalities and autonomous regions) from 1997 to 2019. This classification enriches the study of the pressure on carbon dioxide emissions by specific energy types. By calculating the centre of gravity of the carbon-coal pressure and its evolution trends, the spatial pattern of the carbon-coal pressure and the evolution characteristics of the centre of gravity of the pressure are revealed. The results demonstrate that, despite the continuous growth in total coal consumption and carbon dioxide emissions in China, the carbon-coal pressure index exhibits a decreasing trend in certain regions, with significant interregional differences. Most provinces fall into the high-pressure and higher-pressure categories. The number of high-pressure provinces has decreased by 33% from 18 to 8, while the number of low-pressure provinces has risen from 0 to 1, and both higher and medium pressure types have increased. The overall stress index decreases from 0.79 to 0.7. The pressure centre displays a similar spatial trend to the overall changes in coal consumption and carbon dioxide emissions centre, albeit with a smaller magnitude of change. Beijing stands out as the only province with low pressure.
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| 5. |
- Song, Gongshuai, et al.
(author)
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Mislabeling identification of fresh retail beef cuts using machine learning - guided REIMS lipidomic fingerprints
- 2024
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In: FOOD CONTROL. - 0956-7135 .- 1873-7129. ; 161
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Journal article (peer-reviewed)abstract
- Fraudulent activities such as mislabeling of beef occurred frequently. In this study, a fast and reliable methodology for specific discrimination of fresh retail beef cuts (ribeye, striploin, brisket, beef shank, and fore shank) was established based on electrosurgical knife - rapid evaporative ionization mass spectrometry (iKnife-REIMS) technique integrated with machine learning (ML). REIMS lipidomic fingerprints of various beef cuts were characterized by ML models to explore meaningful information. Authenticity identification models were built by main ML algorithms including discriminant analysis (DA), support vector machines (SVM), and k-nearest neighbor (KNN) to realize the discrimination of mislabeling in beef cuts. Mislabeling discrimination rates of DA, SVM, and KNN were 95.54%, 99.91%, and 100%, respectively. Model performances were evaluated by confusion matrix, receiver operating characteristic curve, and area under the curve. The validation of the proposed REIMS method for detecting mislabeled beef cuts with an accuracy of 96.80% was performed. Results demonstrated that this artificial intelligent method coupled to ML - guided REIMS analysis was efficient for authenticity detection of mislabeled beef cuts.
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| 6. |
- Wang, Yuchen, et al.
(author)
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Field observations of C2 and C3 organosulfates and insights into their formation mechanisms at a suburban site in Hong Kong
- 2023
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In: SCIENCE OF THE TOTAL ENVIRONMENT. - 0048-9697 .- 1879-1026. ; 904
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Journal article (peer-reviewed)abstract
- Organosulfates (OSs) are formed from volatile organic compounds (VOCs) and their oxidation products in the presence of sulfate particles. While OSs represent an important component in secondary organic aerosol, the knowledge of their formation driving force, mechanisms, and environmental impact remain inadequately understood. In this study, we report ambient observations of C2-3 oxygenated VOCs derived OSs (C2-3 OSs) at a suburban location of Hong Kong during autumn 2016. The C2-3 OSs, including glycolaldehyde sulfate (GS), hydroxyacetone sulfate (HAS), glycolic acid sulfate (GAS), and lactic acid sulfate (LAS), were quantified/semiquantified using offline liquid chromatography-mass spectrometry analysis of aerosol filter samples. The average sum concentration of C2-3 OSs was 36 ng/m3. Correlation analysis revealed that sulfate, surface area, and liquid water content were important factors influencing C2-3 OS formation. Online measurement with an iodide High-Resolution Time-of-Flight Chemical-Ionization Mass Spectrometer (HR-ToF-CIMS) coupled with the Filter Inlet for Gases and AEROsols (FIGAERO) was also conducted to monitor C2-3 OSs, and their potential oxygenated VOC precursors in both gas-and particle-phase, and aerosol acidity tracer simultaneously. Our measurements support that glycolaldehyde/glyoxal, hydroxyacetone, glycolic acid/glyoxal, and lactic acid/ methylglyoxal are likely precursors for GS, HAS, GAS, and LAS, respectively. Additionally, we found strong correlation between C2-3 OSs and H3S2O8 , a marker for aerosol acidity, providing field observational evidence for acid-catalyzed formation of small OSs. Based on both online and offline measurements, acid-catalyzed formation mechanisms in particle/aqueous phase are proposed. Specifically, the unique structure of adjacent carbonyl and hydroxyl groups in the C2-3 oxygenated VOC precursors can facilitate the formation of (1) a five member ring intermediate via intramolecular hydrogen bond to react with sulfur trioxide through heterogenous reaction or (2) cyclic sulfate intermediate via particle-phase reaction with sulfuric acid to generate C2-3 OSs. These proposed mechanisms provide an alternative pathway for the liquid-phase production of C2-3 OSs.
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| 7. |
- Wen, Qianyun, et al.
(author)
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Fuzzy Ensemble of Multi-Criteria Decision Making Methods for Heating Energy Transition in Danish Households
- 2021
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In: Mathematics. - : MDPI. - 2227-7390. ; 9:19
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Journal article (peer-reviewed)abstract
- More than 110 countries, including 500 cities worldwide, have set the goal of reaching carbon neutrality. Heating contributes to most of the residential energy consumption and carbon emissions. The green energy transition of fossil-based heating systems is needed to reach the emission goals. However, heating systems vary in energy source, heating technology, equipment location, and these complexities make it challenging for households to compare heating systems and make decisions. Hence, a decision support tool that provides a generalized ranking of individual heating alternatives is proposed for households as decision makers to identify the optimal choice. This paper presents an analysis of 13 heating alternatives and 19 quantitative criteria in technological, environmental, and financial aspects, combines ideal solution-based multi-criteria decision making with 6 weighting methods and 4 normalization methods, and introduces ensemble learning with a fuzzy membership function derived from Cauchy distribution to finalize the ultimate ranking. The robustness of the proposed method is verified by three sensitive analyses from different aspects. Air-to-water heat pump, solar heating and direct district heating are the top three rankings in the final result under Danish national average data. A framework is designed to guide decision makers to apply this ranking guideline with their practical, feasible situations.
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| 8. |
- Wen, Qianyun, et al.
(author)
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How should you heat your home in the green energy transition? A scenario-based multi-criteria decision-making approach
- 2023
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In: Journal of Cleaner Production. - : ELSEVIER SCI LTD. - 0959-6526 .- 1879-1786. ; 421
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Journal article (peer-reviewed)abstract
- The choice of heating system is significant for city planners and building owners alike, and many important areas, such as the well-being of residents, climate change impact and resource efficiency, may influence the choice. Understanding how to balance these areas is crucial for effective decision-making that can contribute to sustainable development and the green energy transition. However, these decisions represent complex problems where disparate knowledge areas must be considered simultaneously. When faced with this type of decisionmaking problem, employing different multi-criteria decision-making methods is common. However, such methods only provide a snapshot of which alternative is preferred and because of this, their results may become obsolete due to changes in the performance of alternatives or the value perceptions of the decision-makers. To overcome this challenge and to improve the longevity and reliability of multi-criteria decision-making results, the authors of this study explored a novel approach to producing semi-dynamic results through scenarios, which were used to consider possible future changes to the alternatives performance and the decision-makers value perceptions. The application of scenarios in the multi-criteria decision-making method enabled nuanced information to be produced on how the performance of different heating alternatives may change under different plausible futures. This approach was demonstrated by applying it to the case of residential heating in Denmark, where results showed that while final rankings varied across both scenarios and ranking methods, solar heating was the preferred alternative, while the oil boiler alternative performed the worst. Overall, this study highlights the importance of considering likely future changes to both the performance of alternatives and the value perceptions of decision-makers when making decisions with long lifetimes and suggests an approach for doing this.
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| 9. |
- Zhang, Tianji, et al.
(author)
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Oligosaccharides mapping of nitrous acid degraded heparin through UHPLC-HILIC/WAX-MS
- 2020
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In: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 231
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Journal article (peer-reviewed)abstract
- Building blocks characterization is a significant approach for understanding the molecular structure of heparin and its derivatives. Nitrous acid (HONO) depolymerization of heparin generates oligosaccharides that maintain the epimerization conformation on C5 of the uronic acids, reflecting the authentic structure of the parental chain. HONO treatment at pH 1.5 selectively cleaves the bond between N-sulfated glucosamine and hexuronic acid, resulting mainly disaccharides, as well as tetra-, tri-, and mono-saccharides. The tetrasaccharides are derived from the structure of N-acetylated domains while tri-, and mono-saccharides are derived from the reducing or the non-reducing end of the heparin chain. The resulted oligosaccharides were separated and analyzed using a UHPLC-HILIC/WAX-MS method. We succeeded in the identification of 19 tetrasaccharides, 19 trisaccharides and 4 monosaccharides species, majority of which is structurally characterized. By comparing the theoretical possibilities and actual occurrence of the well-characterized tetrasaccharides, we demonstrated that the biosynthesis of heparin is a systematic process.
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