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Zeitschriftenartikel zum Thema "Rolling PMF"
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Via, Marta, Gang Chen, Francesco Canonaco, Kaspar R. Daellenbach, Benjamin Chazeau, Hasna Chebaicheb, Jianhui Jiang et al. „Rolling vs. seasonal PMF: real-world multi-site and synthetic dataset comparison“. Atmospheric Measurement Techniques 15, Nr. 18 (27.09.2022): 5479–95. http://dx.doi.org/10.5194/amt-15-5479-2022.
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Abstract. Particulate matter (PM) has become a major concern in terms of human health and climate impact. In particular, the source apportionment (SA) of organic aerosols (OA) present in submicron particles (PM1) has gained relevance as an atmospheric research field due to the diversity and complexity of its primary sources and secondary formation processes. Moreover, relatively simple but robust instruments such as the Aerosol Chemical Speciation Monitor (ACSM) are now widely available for the near-real-time online determination of the composition of the non-refractory PM1. One of the most used tools for SA purposes is the source-receptor positive matrix factorisation (PMF) model. Even though the recently developed rolling PMF technique has already been used for OA SA on ACSM datasets, no study has assessed its added value compared to the more common seasonal PMF method using a practical approach yet. In this paper, both techniques were applied to a synthetic dataset and to nine European ACSM datasets in order to spot the main output discrepancies between methods. The main advantage of the synthetic dataset approach was that the methods' outputs could be compared to the expected “true” values, i.e. the original synthetic dataset values. This approach revealed similar apportionment results amongst methods, although the rolling PMF profile's adaptability feature proved to be advantageous, as it generated output profiles that moved nearer to the truth points. Nevertheless, these results highlighted the impact of the profile anchor on the solution, as the use of a different anchor with respect to the truth led to significantly different results in both methods. In the multi-site study, while differences were generally not significant when considering year-long periods, their importance grew towards shorter time spans, as in intra-month or intra-day cycles. As far as correlation with external measurements is concerned, rolling PMF performed better than seasonal PMF globally for the ambient datasets investigated here, especially in periods between seasons. The results of this multi-site comparison coincide with the synthetic dataset in terms of rolling–seasonal similarity and rolling PMF reporting moderate improvements. Altogether, the results of this study provide solid evidence of the robustness of both methods and of the overall efficiency of the recently proposed rolling PMF approach.
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Lin, Chunshui, Darius Ceburnis, Colin O’Dowd und Jurgita Ovadnevaite. „Seasonality of Aerosol Sources Calls for Distinct Air Quality Mitigation Strategies“. Toxics 10, Nr. 3 (03.03.2022): 121. http://dx.doi.org/10.3390/toxics10030121.
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An Aerosol Chemical Speciation Monitor (ACSM) was deployed to investigate the temporal variability of non-refractory particulate matter (NR-PM1) in the coastal city of Galway, Ireland, from February to July 2016. Source apportionment of the organic aerosol (OA) was performed using the newly developed rolling PMF strategy and was compared with the conventional seasonal PMF. Primary OA (POA) factors apportioned by rolling and seasonal PMF were similar. POA factors of hydrocarbon-like OA (HOA), peat, wood, and coal were associated with domestic heating, and with an increased contribution to the OA mass in winter. Even in summer, sporadic heating events occurred with similar diurnal patterns to that in winter. Two oxygenated OA (OOA) factors were resolved, including more-oxygenated OOA and less-oxygenated OOA (i.e., MO-OOA and LO-OOA, accordingly) which were found to be the dominant OA factors during summer. On average, MO-OOA accounted for 62% of OA and was associated with long-range transport in summer. In summer, compared to rolling PMF, the conventional seasonal PMF over-estimated LO-OOA by nearly 100% while it underestimated MO-OOA by 30%. The results from this study show residential heating and long-range transport alternately dominate the submicron aerosol concentrations in this coastal city, requiring different mitigation strategies in different seasons.
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Wang, Qiongqiong, Shuhui Zhu, Shan Wang, Cheng Huang, Yusen Duan und Jian Zhen Yu. „Short-term source apportionment of fine particulate matter with time-dependent profiles using SoFi Pro: exploring the reliability of rolling positive matrix factorization (PMF) applied to bihourly molecular and elemental tracer data“. Atmospheric Chemistry and Physics 24, Nr. 1 (12.01.2024): 475–86. http://dx.doi.org/10.5194/acp-24-475-2024.
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Abstract. Positive matrix factorization (PMF) has been widely used to apportion the sources of fine particulate matter (PM2.5) by utilizing PM chemical speciation data measured at the receptor site(s). Traditional PMF, which typically relies on long-term observational datasets of daily or lower time resolution to meet the required sample size, has its reliability undermined by changes in source profiles; thus, it is inherently ill-suited for apportioning sporadic sources or ephemeral pollution events. In this study, we explored short-term source apportionment of PM2.5 using a set of bihourly chemical speciation data over a period of 37 d in the winter of 2019–2020. PMF run with campaign-wide data as input (PMFref) was initially conducted to obtain reference profiles for the primary source factors. Subsequently, short-term PMF analysis was performed using the Source Finder Professional (SoFi Pro). The analysis sets a window length of 18 d and constrained the primary source profiles using the a-value approach embedded in SoFi Pro software. Rolling PMF was then conducted with a fixed window length of 18 d and a step of 1 d using the remaining dataset. By applying the a-value constraints to the primary sources, the rolling PMF effectively reproduced the individual primary sources, as evidenced by the slope values close to unity (i.e., 0.9–1.0). However, the estimation for the firework emission factor in the rolling PMF was lower compared with PMFref (slope: 0.8). These results suggest the unique advantage of short-term PMF analysis in accurately apportioning sporadic sources. Although the total secondary sources were well modeled (slope: 1.0), larger biases were observed for individual secondary sources. The variation in source profiles indicated higher variabilities for the secondary sources, with average relative differences ranging from 42 % to 173 %, while the primary source profiles exhibited much smaller variabilities (relative differences of 8 %–26 %). This study suggests that short-term PMF analysis with the a-value constraints in SoFi Pro can be utilized to apportion primary sources accurately, while future efforts are needed to improve the prediction of individual secondary sources. Additionally, future rapid source apportionment analysis can benefit from utilizing a library of source profiles derived from existing measurement data, thereby significantly reducing the time lag associated with receptor modeling source apportionment techniques.
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Chen, Gang, Yulia Sosedova, Francesco Canonaco, Roman Fröhlich, Anna Tobler, Athanasia Vlachou, Kaspar R. Daellenbach et al. „Time-dependent source apportionment of submicron organic aerosol for a rural site in an alpine valley using a rolling positive matrix factorisation (PMF) window“. Atmospheric Chemistry and Physics 21, Nr. 19 (11.10.2021): 15081–101. http://dx.doi.org/10.5194/acp-21-15081-2021.
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Abstract. We collected 1 year of aerosol chemical speciation monitor (ACSM) data in Magadino, a village located in the south of the Swiss Alpine region, one of Switzerland's most polluted areas. We analysed the mass spectra of organic aerosol (OA) by positive matrix factorisation (PMF) using Source Finder Professional (SoFi Pro) to retrieve the origins of OA. Therein, we deployed a rolling algorithm, which is closer to the measurement, to account for the temporal changes in the source profiles. As the first-ever application of rolling PMF with multilinear engine (ME-2) analysis on a yearlong dataset that was collected from a rural site, we resolved two primary OA factors (traffic-related hydrocarbon-like OA (HOA) and biomass burning OA (BBOA)), one mass-to-charge ratio (m/z) 58-related OA (58-OA) factor, a less oxidised oxygenated OA (LO-OOA) factor, and a more oxidised oxygenated OA (MO-OOA) factor. HOA showed stable contributions to the total OA through the whole year ranging from 8.1 % to 10.1 %, while the contribution of BBOA showed an apparent seasonal variation with a range of 8.3 %–27.4 % (highest during winter, lowest during summer) and a yearly average of 17.1 %. OOA (sum of LO-OOA and MO-OOA) contributed 71.6 % of the OA mass, varying from 62.5 % (in winter) to 78 % (in spring and summer). The 58-OA factor mainly contained nitrogen-related variables which appeared to be pronounced only after the filament switched. However, since the contribution of this factor was insignificant (2.1 %), we did not attempt to interpolate its potential source in this work. The uncertainties (σ) for the modelled OA factors (i.e. rotational uncertainty and statistical variability in the sources) varied from ±4 % (58-OA) to a maximum of ±40 % (LO-OOA). Considering that BBOA and LO-OOA (showing influences of biomass burning in winter) had significant contributions to the total OA mass, we suggest reducing and controlling biomass-burning-related residential heating as a mitigation strategy for better air quality and lower PM levels in this region or similar locations. In Appendix A, we conduct a head-to-head comparison between the conventional seasonal PMF analysis and the rolling mechanism. We find similar or slightly improved results in terms of mass concentrations, correlations with external tracers, and factor profiles of the constrained POA factors. The rolling results show smaller scaled residuals and enhanced correlations between OOA factors and corresponding inorganic salts compared to those of the seasonal solutions, which was most likely because the rolling PMF analysis can capture the temporal variations in the oxidation processes for OOA components. Specifically, the time-dependent factor profiles of MO-OOA and LO-OOA can well explain the temporal viabilities of two main ions for OOA factors, m/z 44 (CO2+) and m/z 43 (mostly C2H3O+). Therefore, this rolling PMF analysis provides a more realistic source apportionment (SA) solution with time-dependent OA sources. The rolling results also show good agreement with offline Aerodyne aerosol mass spectrometer (AMS) SA results from filter samples, except for in winter. The latter discrepancy is likely because the online measurement can capture the fast oxidation processes of biomass burning sources, in contrast to the 24 h filter samples. This study demonstrates the strengths of the rolling mechanism, provides a comprehensive criterion list for ACSM users to obtain reproducible SA results, and is a role model for similar analyses of such worldwide available data.
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Canonaco, Francesco, Anna Tobler, Gang Chen, Yulia Sosedova, Jay Gates Slowik, Carlo Bozzetti, Kaspar Rudolf Daellenbach et al. „A new method for long-term source apportionment with time-dependent factor profiles and uncertainty assessment using SoFi Pro: application to 1 year of organic aerosol data“. Atmospheric Measurement Techniques 14, Nr. 2 (08.02.2021): 923–43. http://dx.doi.org/10.5194/amt-14-923-2021.
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Abstract. A new methodology for performing long-term source apportionment (SA) using positive matrix factorization (PMF) is presented. The method is implemented within the SoFi Pro software package and uses the multilinear engine (ME-2) as a PMF solver. The technique is applied to a 1-year aerosol chemical speciation monitor (ACSM) dataset from downtown Zurich, Switzerland. The measured organic aerosol mass spectra were analyzed by PMF using a small (14 d) and rolling PMF window to account for the temporal evolution of the sources. The rotational ambiguity is explored and the uncertainties of the PMF solutions were estimated. Factor–tracer correlations for averaged seasonal results from the rolling window analysis are higher than those retrieved from conventional PMF analyses of individual seasons, highlighting the improved performance of the rolling window algorithm for long-term data. In this study four to five factors were tested for every PMF window. Factor profiles for primary organic aerosol from traffic (HOA), cooking (COA) and biomass burning (BBOA) were constrained. Secondary organic aerosol was represented by either the combination of semi-volatile and low-volatility organic aerosol (SV-OOA and LV-OOA, respectively) or by a single OOA when this separation was not robust. This scheme led to roughly 40 000 PMF runs. Full visual inspection of all these PMF runs is unrealistic and is replaced by predefined user-selected criteria, which allow factor sorting and PMF run acceptance/rejection. The selected criteria for traffic (HOA) and BBOA were the correlation with equivalent black carbon from traffic (eBCtr) and the explained variation of m/z 60, respectively. COA was assessed by the prominence of a lunchtime concentration peak within the diurnal cycle. SV-OOA and LV-OOA were evaluated based on the fractions of m/z 43 and 44 in their respective factor profiles. Seasonal pre-tests revealed a non-continuous separation of OOA into SV-OOA and LV-OOA, in particular during the warm seasons. Therefore, a differentiation between four-factor solutions (HOA, COA, BBOA and OOA) and five-factor solutions (HOA, COA, BBOA, SV-OOA and LV-OOA) was also conducted based on the criterion for SV-OOA. HOA and COA contribute between 0.4–0.7 µg m−3 (7.8 %–9.0 %) and 0.7–1.2 µg m−3 (12.2 %–15.7 %) on average throughout the year, respectively. BBOA shows a strong yearly cycle with the lowest mean concentrations in summer (0.6 µg m−3, 12.0 %), slightly higher mean concentrations during spring and fall (1.0 and 1.5 µg m−3, or 15.6 % and 18.6 %, respectively), and the highest mean concentrations during winter (1.9 µg m−3, 25.0 %). In summer, OOA is separated into SV-OOA and LV-OOA, with mean concentrations of 1.4 µg m−3 (26.5 %) and 2.2 µg m−3 (40.3 %), respectively. For the remaining seasons the seasonal concentrations of SV-OOA, LV-OOA and OOA range from 0.3 to 1.1 µg m−3 (3.4 %–15.9 %), from 0.6 to 2.2 µg m−3 (7.7 %–33.7 %) and from 0.9 to 3.1 µg m−3 (13.7 %–39.9 %), respectively. The relative PMF errors modeled for this study for HOA, COA, BBOA, LV-OOA, SV-OOA and OOA are on average ±34 %, ±27 %, ±30 %, ±11 %, ±25 % and ±12 %, respectively.
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Yang, Xu, XianGuo Li, DeJun Meng, Jia Shi und ChangYun Miao. „Optical fiber vibration sensor for bearing fault detection based on Sagnac interferometer“. Laser Physics 33, Nr. 6 (13.04.2023): 065101. http://dx.doi.org/10.1088/1555-6611/acca04.
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Abstract Bearings are crucial components in mechanical equipment, and bearing failure is one of the reasons for mechanical equipment safety accidents. In this work, an optical fiber vibration sensor based on Sagnac interferometer (SI) is proposed and applied to bearing fault detection. The polarization-maintaining fiber (PMF) is spliced between two single-mode fibers (SMFs) to form a SMF-PMF-SMF (SPS) fiber structure, which is connected with a 3 dB coupler to form a SI based on SPS fiber structure. The mass block is fixed in the middle of the PMF. When the monitored surface or structure vibrates, the stress of PMF will change and the Sagnac interference spectrum will be shifted, so that the vibration can be measured. The fabrication technology of sensor based on 3D printing is studied, and the structural parameters of the sensor are optimized through experiments and theoretical analysis. A vibration detection system and a rolling bearing vibration test platform based on SI and fiber ring laser are built. The experimental results show that the relative error between the experimental and theoretical results of healthy and faulty bearings is less than 1.60%, and the fault detection of bearings is realized. Temperature cross-sensitivity and stability of the sensing system are analyzed. The sensor has the advantages of simple structure, easy fabrication, anti-interference, etc, and has wide application prospects in engineering, machinery, security and other fields.
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Zografou, Olga, Maria Gini, Manousos I. Manousakas, Gang Chen, Athina C. Kalogridis, Evangelia Diapouli, Athina Pappa und Konstantinos Eleftheriadis. „Combined organic and inorganic source apportionment on yearlong ToF-ACSM dataset at a suburban station in Athens“. Atmospheric Measurement Techniques 15, Nr. 16 (17.08.2022): 4675–92. http://dx.doi.org/10.5194/amt-15-4675-2022.
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Abstract. The current improvements in aerosol mass spectrometers in resolution and sensitivity, and the analytical tools for mass spectra deconvolution, have enabled the in-depth analysis of ambient organic aerosol (OA) properties. Although OA constitutes a major fraction of ambient aerosol, its properties are determined to a great extent by the mixing characteristics of both organic and inorganic components of ambient aerosol. This work applies a new methodology to a year-long ACSM dataset to assess the sources of organic and total non-refractory species in the Athens background aerosol and provides insights into the interactions between organic and inorganic species. The use of innovative tools for applying positive matrix factorization (PMF, rolling window) enables the study of the temporal variability of the contribution of these sources and seasonal changes in their composition. The mass spectra of both organic and inorganic aerosol were obtained by a time-of-flight aerosol mass spectrometer (ToF-ACSM) for PMF analysis. The results revealed five factors when organic aerosol was analysed separately. Three of them were primary OA factors: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA) and biomass burning organic aerosol (BBOA). The remaining two were secondary, less and more oxidized oxygenated organic aerosol (LO-OOA and MO-OOA respectively). The relative contributions of these factors were HOA 15 %, COA 18 %, BBOA 9 %, MO-OOA 34 % and LO-OOA 24 % (yearly averaged). When a combined organic and inorganic aerosol matrix was analysed, two additional factors were identified that were mainly composed of ammonium sulfate (83.5 %) and ammonium nitrate (73 %). Moreover, two secondary factors were resolved, containing both organics and inorganics and were named more (MOA) and less oxidized aerosol (LOA). The relative contributions on a yearly average of these factors were HOA 7 %, COA 9 %, BBOA 3 %, ammonium nitrate 3 %, ammonium sulfate 28 %, MOA 24 % and LOA 26 %.
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Heikkinen, Liine, Mikko Äijälä, Kaspar R. Daellenbach, Gang Chen, Olga Garmash, Diego Aliaga, Frans Graeffe et al. „Eight years of sub-micrometre organic aerosol composition data from the boreal forest characterized using a machine-learning approach“. Atmospheric Chemistry and Physics 21, Nr. 13 (06.07.2021): 10081–109. http://dx.doi.org/10.5194/acp-21-10081-2021.
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Abstract. The Station for Measuring Ecosystem–Atmosphere Relations (SMEAR) II, located within the boreal forest of Finland, is a unique station in the world due to the wide range of long-term measurements tracking the Earth–atmosphere interface. In this study, we characterize the composition of organic aerosol (OA) at SMEAR II by quantifying its driving constituents. We utilize a multi-year data set of OA mass spectra measured in situ with an Aerosol Chemical Speciation Monitor (ACSM) at the station. To our knowledge, this mass spectral time series is the longest of its kind published to date. Similarly to other previously reported efforts in OA source apportionment from multi-seasonal or multi-annual data sets, we approached the OA characterization challenge through positive matrix factorization (PMF) using a rolling window approach. However, the existing methods for extracting minor OA components were found to be insufficient for our rather remote site. To overcome this issue, we tested a new statistical analysis framework. This included unsupervised feature extraction and classification stages to explore a large number of unconstrained PMF runs conducted on the measured OA mass spectra. Anchored by these results, we finally constructed a relaxed chemical mass balance (CMB) run that resolved different OA components from our observations. The presented combination of statistical tools provided a data-driven analysis methodology, which in our case achieved robust solutions with minimal subjectivity. Following the extensive statistical analyses, we were able to divide the 2012–2019 SMEAR II OA data (mass concentration interquartile range (IQR): 0.7, 1.3, and 2.6 µg m−3) into three sub-categories – low-volatility oxygenated OA (LV-OOA), semi-volatile oxygenated OA (SV-OOA), and primary OA (POA) – proving that the tested methodology was able to provide results consistent with literature. LV-OOA was the most dominant OA type (organic mass fraction IQR: 49 %, 62 %, and 73 %). The seasonal cycle of LV-OOA was bimodal, with peaks both in summer and in February. We associated the wintertime LV-OOA with anthropogenic sources and assumed biogenic influence in LV-OOA formation in summer. Through a brief trajectory analysis, we estimated summertime natural LV-OOA formation of tens of ng m−3 h−1 over the boreal forest. SV-OOA was the second highest contributor to OA mass (organic mass fraction IQR: 19 %, 31 %, and 43 %). Due to SV-OOA's clear peak in summer, we estimate biogenic processes as the main drivers in its formation. Unlike for LV-OOA, the highest SV-OOA concentrations were detected in stable summertime nocturnal surface layers. Two nearby sawmills also played a significant role in SV-OOA production as also exemplified by previous studies at SMEAR II. POA, taken as a mix of two different OA types reported previously, hydrocarbon-like OA (HOA) and biomass burning OA (BBOA), made up a minimal OA mass fraction (IQR: 2 %, 6 %, and 13 %). Notably, the quantification of POA at SMEAR II using ACSM data was not possible following existing rolling PMF methodologies. Both POA organic mass fraction and mass concentration peaked in winter. Its appearance at SMEAR II was linked to strong southerly winds. Similar wind direction and speed dependence was not observed among other OA types. The high wind speeds probably enabled the POA transport to SMEAR II from faraway sources in a relatively fresh state. In the event of slower wind speeds, POA likely evaporated and/or aged into oxidized organic aerosol before detection. The POA organic mass fraction was significantly lower than reported by aerosol mass spectrometer (AMS) measurements 2 to 4 years prior to the ACSM measurements. While the co-located long-term measurements of black carbon supported the hypothesis of higher POA loadings prior to year 2012, it is also possible that short-term (POA) pollution plumes were averaged out due to the slow time resolution of the ACSM combined with the further 3 h data averaging needed to ensure good signal-to-noise ratios (SNRs). Despite the length of the ACSM data set, we did not focus on quantifying long-term trends of POA (nor other components) due to the high sensitivity of OA composition to meteorological anomalies, the occurrence of which is likely not normally distributed over the 8-year measurement period. Due to the unique and realistic seasonal cycles and meteorology dependences of the independent OA subtypes complemented by the reasonably low degree of unexplained OA variability, we believe that the presented data analysis approach performs well. Therefore, we hope that these results encourage also other researchers possessing several-year-long time series of similar data to tackle the data analysis via similar semi- or unsupervised machine-learning approaches. This way the presented method could be further optimized and its usability explored and evaluated also in other environments.
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Atabakhsh, Samira, Laurent Poulain, Gang Chen, Francesco Canonaco, André S. H. Prévôt, Mira Pöhlker, Alfred Wiedensohler und Hartmut Herrmann. „A 1-year aerosol chemical speciation monitor (ACSM) source analysis of organic aerosol particle contributions from anthropogenic sources after long-range transport at the TROPOS research station Melpitz“. Atmospheric Chemistry and Physics 23, Nr. 12 (23.06.2023): 6963–88. http://dx.doi.org/10.5194/acp-23-6963-2023.
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Abstract. Atmospheric aerosol particles are a complex combination of primary emitted sources (biogenic and anthropogenic) and secondary aerosol resulting from aging processes such as condensation, coagulation, and cloud processing. To better understand their sources, investigations have been focused on urban areas in the past, whereas rural-background stations are normally less impacted by surrounding anthropogenic sources. Therefore, they are predisposed for studying the impact of long-range transport of anthropogenic aerosols. Here, the chemical composition and organic aerosol (OA) sources of submicron aerosol particles measured by an aerosol chemical speciation monitor (ACSM) and a multi-angle absorption photometer (MAAP) were investigated at Melpitz from September 2016 to August 2017. The location of the station at the frontier between western and eastern Europe makes it the ideal place to investigate the impact of long-range transport over Europe. Indeed, the station is under the influence of less polluted air masses from westerly directions and more polluted continental air masses from eastern Europe. The OA dominated the submicron particle mass concentration and showed strong seasonal variability ranging from 39 % (in winter) to 58 % (in summer). It was followed by sulfate (15 % and 20 %) and nitrate (24 % and 11 %). The OA source identification was performed using the rolling positive matrix factorization (PMF) approach to account for the potential temporal changes in the source profile. It was possible to split OA into five factors with a distinct temporal variability and mass spectral signature. Three were associated with anthropogenic primary OA (POA) sources: hydrocarbon-like OA (HOA; 5.2 % of OA mass in winter and 6.8 % in summer), biomass burning OA (BBOA; 10.6 % and 6.1 %) and coal combustion OA (CCOA; 23 % and 8.7 %). Another two are secondary and processed oxygenated OA (OOA) sources: less oxidized OOA (LO-OOA; 28.4 % and 36.7 %) and more oxidized OOA (MO-OOA; 32.8 % and 41.8 %). Since equivalent black carbon (eBC) was clearly associated with the identified POA factors (sum of HOA, BBOA, and CCOA; R2= 0. 87), eBC's contribution to each of the POA factors was achieved using a multilinear regression model. Consequently, CCOA represented the main anthropogenic sources of carbonaceous aerosol (sum of OA and eBC) not only during winter (56 % of POA in winter) but also in summer (13 % of POA in summer), followed by BBOA (29 % and 69 % of POA in winter and summer, respectively) and HOA (15 % and 18 % of POA in winter and summer, respectively). A seasonal air mass cluster analysis was used to understand the geographical origins of the different aerosol types and showed that during both winter and summer time, PM1 (PM with an aerodynamic diameter smaller than 1 µm) air masses with eastern influence were always associated with the highest mass concentration and the highest coal combustion fraction. Since during wintertime CCOA is a combination of domestic heating and power plant emissions, the summer contribution of CCOA emphasizes the critical importance of coal power plant emissions to rural-background aerosols and its impact on air quality, through long-range transportation.
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SHINOHARA, T., und K. YOSHIDA. „PLF-13: Deformation Analysis of Surface Crack in Rolling and Wire Drawing(PLF-III: PLASTIC FORMING AND ADVANCED PRODUCTS)“. Proceedings of the JSME Materials and Processing Conference (M&P) 2005 (2005): 39–40. http://dx.doi.org/10.1299/jsmeintmp.2005.39_6.
Der volle Inhalt der QuelleDissertationen zum Thema "Rolling PMF"
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Chebaicheb, Hasna. „Etude de la composition chimique des particules fines et des sources d'aérosol organique sur différents sites en France à partir de jeux de données pluriannuels à haute résolution temporelle“. Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Lille Douai, 2023. http://www.theses.fr/2023MTLD0006.
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Considérant les impacts climatiques et sanitaires majeurs des particules fines, ce travail a étudié leur composition chimique sur 13 sites français de 2015 à 2021. L’aérosol organique (AO) prédomine, avec des augmentations en hiver (chauffage résidentiel), et en été (formation d’aérosols organiques secondaires). Le nitrate d’ammonium, polluant secondaire lui aussi issu des combustions et de l’agriculture, domine en particulier dans le nord lors des épisodes de pollution printaniers.Les sources principales de l’Ao sont liées principalement aux émissions du trafic et de la combustion de biomasse. D’autres sont spécifiques à certains sites (activités de cuisson, industrie, émissions des navires). Les facteurs oxygénés dominent l’AO, suggérant des processus de vieillissement et de formation secondaire. Ces résultats peuvent orienter les politiques visant à améliorer la qualité de l’air, contribuer à améliorer la précision des modèles et servir à de futures études épidémiologiquesConsidering the major climatic and health impacts of fine particulate matter, this work studies their chemical composition at 13 French sites from 2015 to 2021. Organic aerosols (OA) predominate, with increases in winter (residential heating emissions) and summer (formation of secondary organic aerosols). Ammonium nitrate, also a secondary pollutant from combustion and agriculture, dominates during springtime pollution episodes, particularly in the north.The main sources of OA are traffic emissions and biomass combustion. Others are site-specific (cooking activities, industry, ship emissions). Oxygenated factors dominate OA, suggesting aging and secondary formation processes. These results can guide policies aimed at improving air quality, help improve the model accuracy and inform future epidemiological studies)
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Thomas, Jeff Scott. „Plastic fiber rolling for concrete reinforcement“. Diss., Rolla, Mo. : University of Missouri-Rolla, 1996. http://scholarsmine.mst.edu/thesis/pdf/Thomas_09007dcc805b0f25.pdf.
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Thesis (M.S.)--University of Missouri--Rolla, 1996.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 24, 2008) Includes bibliographical references (p. 117-118).
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Devisetti, Suresh K. „Pressure Distribution and Transfer in Rolling Nips“. Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/DevisettiSK2004.pdf.
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Halverson, Peter Andrew. „Multi-stable Compliant Rolling-contact Elements“. Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1832.pdf.
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McCarthy, Erik L. „Selective Biomolecular Layers for Surface-associated Rolling Circle Amplification“. Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/McCarthyEL2006.pdf.
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Montierth, Jacob R. „Elliptical rolling link toggle mechanisms for passive force closures with self-adjustment /“. Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2032.pdf.
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Siciliano, Fulvio. „Mathematical modeling of the hot strip rolling of Nb microalloyed steels“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0023/NQ50261.pdf.
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Chertok, Daniel. „Hysteretic friction in the transient rolling contact problem of linear viscoelasticity“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0001/NQ37689.pdf.
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Purcell, Anne. „Mathematical modelling of temperature evolution in the hot rolling of steel“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0029/MQ64245.pdf.
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Worley, John C. Ahmed Anwar. „Yaw-roll coupled oscillations of a slender delta wing“. Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Aerospace_Engineering/Thesis/Worley_John_37.pdf.
Der volle Inhalt der QuelleBücher zum Thema "Rolling PMF"
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DIMON, Vicki. Hourly Study Planner - It's a Diesel Thing Black Smoke Trucks Rolling Coal. pdf. Independently Published, 2021.
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WHEAT, K. I. M. Grandma Rolling Skate Birthday Matching Party Family. pdf: Papercode Lined Journal - 6 X 9 Inch, 120 Page Notebooks for Work, Writing, Note Taking, Travel - Matte Finish Cover College Ruled Journal for Men and Women. Independently Published, 2022.
Den vollen Inhalt der Quelle findenKonferenzberichte zum Thema "Rolling PMF"
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Wendel, John C., Andrew W. Nelson, Arif S. Malik und Mark E. Zipf. „Bayesian-Based Probabilistic Force Modeling in Cold Rolling“. In ASME 2013 International Manufacturing Science and Engineering Conference collocated with the 41st North American Manufacturing Research Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/msec2013-1226.
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A primary factor in manufacturing high-quality cold-rolled sheet is the ability to accurately predict the required rolling force. The rolling force directly influences roll-stack deflections, which correlate to the resulting flatness quality of the rolled sheet. Increasingly high demand for thin and ultra-thin gauge for cold-rolled sheet metals, along with the correspondingly larger sensitivity of flatness defects when rolling thin gauges, makes it more important to accurately and rapidly predict the rolling force before the rolling operation begins. Accurate rolling force predictions enable assignment of appropriate pass schedules and flatness mechanism set-points early in the rolling process, thereby reducing rolling time, improving quality, and reducing scrap. Traditionally, force predictions in cold rolling have employed two-dimensional analytical models such as those proposed by Roberts and by Bland & Ford. These simplified methods are prone to inaccuracy, however, because of several uncertain, yet influential, model parameters that are difficult to establish deterministically for wide-ranging products. These parameters include, for example, the average compressive yield strength of the rolled strip, frictional characteristics relating to low and high mill speeds, and the strain rate dependency of yield strength. Conventionally, these unknown parameters have been evaluated deterministically by comparing force predictions with actual rolling force data and using a best-fit regression approach. In this work, Bayesian updating using a probability mass function (PMF) is applied to identify joint posterior probability distributions of the uncertain parameters in rolling force models. It is shown that the non-deterministic Bayesian updating approach is particularly useful as new evidence becomes available in the form of additional rolling force data. The aim of the work is to incorporate Bayesian inference into rolling force prediction for cold rolling mills to create a probabilistic modeling approach which can also “learn” as new production data is added. The goal is a model that can better predict necessary mill parameters based on accurate probability estimates of the actual rolling force. The rolling force data used in this work for applying Bayesian updating is actual production data of grades 301 and 304L (low carbon) stainless steels, rolled on a 10-inch wide 4-high cold rolling mill. This force data was collected by observing and averaging load cell measurements at steady rolling speeds.
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Skierczynski, Boguslaw A. „Probability Density of the Rolling Velocity of the Cell“. In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0056.
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Abstract Rolling of the cell under flow conditions is an important process in PMN emigration. It is a finely regulated process involving membrane receptors and cell-matrix recognition. Several models have been proposed to explain how the strength and lifetime of the bonds in receptor-mediated cell-substratum are related to cell rolling velocity (Hammer, 1992, Tozeren, 1992, Zhao, 1995). The paper presents a simple model of the cell rolling based on the experimental measurements that will allow to gain information relevant to the molecular processes underlying the rolling motion of the cell.
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Duan, Zhixiang, Jingjun Yu und Xianwen Kong. „Axode Characteristic of 4-4R Parallel Pointing Mechanism“. In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46839.
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Axodes of a spatial mechanism can reveal plenty of information about its motion characteristic. Through the research of the axodes, the mechanism’s motion patterns can be more intuitively understood, which provides lots of help to exploring its further application. However, compared with one-DOF (degree of freedom) spatial mechanism, the research on axodes of multi-DOF PMs (parallel mechanisms) is scarce. Thus, this paper mainly investigates the axodes of a typical 2-DOF rotational PM, i.e. the 4-4R pointing mechanism, also called as Omni Wrist III, and further discloses its distinctive rolling characteristics. The final objective is to extend the application of the 4-4R pointing mechanism based on its axode characteristic. For this purpose, a rapid graphic-based algorithm for calculating the fixed and moving axodes of the 4-4R pointing mechanism is presented considering its particular geometrical arrangement. Based on the algorithm and further axode analysis, three special motion patterns existing in the mechanism, i.e. pure conical rolling, pure cylindrical rolling and pure spherical rolling, are disclosed. According to its axodes characteristic, the application of the 4-4R pointing mechanism can be extended to design of new spherical gears and constant-velocity couplings, etc.
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Shanbhag, Ganesh. „Pedestrian head injury prediction based on vehicle section image using machine learning.“ In FISITA World Congress 2021. FISITA, 2021. http://dx.doi.org/10.46720/f2021-pif-066.
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Child occupant injury performance evaluation is integral part of most Consumer based and Insurance based vehicle safety evaluation protocols worldwide. New CAR Assessment Protocols (NCAP) now have separate ratings exclusively to evaluate Child dummy performance for different test scenarios like Frontal ODB, Full frontal, Side MDB and Side Pole etc. Hence all vehicle equipment manufacturers have need and focus of maximizing child injury performance in vehicles. Sled tests are proven method of optimizing various restraint systems like Seat belts, Driver Airbags, Passenger Airbags, Steering columns and Seats etc. Obvious benefits sled tests is that single fixture can be used for multiple tests, thereby avoiding the need of multiple vehicles in development stage which are quite expensive at early stages of vehicle development. For frontal type of impact cases, acceleration or deceleration based sled tests can be used depending on test facility available. In typical frontal impact scenarios like Frontal impact with rigid wall, Offset barrier impact or Pole impacts vehicle will be subjected to Pitching, Yawing and Rolling motion before bouncing back motion. Obviously, the motions are pronounced as we move front of vehicle to rear end. (from first row to second row and third row if any etc) Sled tests are conventionally used for tuning restraints in first row of occupants with good correlation, as effect of pitch, roll and yaw motions in first row are relatively less. However, as one move to second row, effect of pitching and rolling motions experienced by dummies are relatively high. Hence one should be careful of results from sled test. In the present study an attempt is made to simulate child injury performance of P3 dummy positioned on second row seat on defined child seat for 64 kmph frontal Offset deformed barrier type test. Sled pulses are carefully tuned to capture key injury patterns. Thence restraint parameters are tuned to improve child dummy injuries. In the last part of study correlated sled model will be used to compare P3 series child dummies vs Q3 series of child dummies. A comparative study of P3 vs Q3 dummies will be presented for a given vehicle pulse.
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Schlemminger, A., und K. Hofmann. „PMI 4.0 — How LIBS Technology Can Streamline Frequent Steel Grade Changes in Rolling Mills and Finishing Lines“. In AISTech 2020. AIST, 2020. http://dx.doi.org/10.33313/380/147.
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Ma, Chengqian, Ning Ma und Xiechong Gu. „Time Domain Simulations of Ship Maneuvering and Roll Motion in Regular Waves Based on a Hybrid Method“. In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95562.
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Abstract Ship maneuvering performance and rolling in waves under complicated environmental conditions are of significant importance for safety and economic reasons. The existing methods for predicting the maneuvering in adverse sea conditions can be categorized into unified two-time scale model, hybrid approach and CFD method. However, traditional potential methods rely tightly on ship viscous force data from test results, and CFD methods of free running ship require large computational resources consumption. In this paper, a 4-DOF (surge, sway, yaw and roll) model based on MMG method considering the wave effect is established to predict the trajectory and rolling motion with better time efficiency. The 1st order wave force and mean 2nd order drift force in this time-domain model are calculated by the 3D panel method and Cummins impose response function. Instead of model experiments, the hydrodynamic derivatives in the maneuvering model can be calculated by RANS-based numerical simulations of the Planar Motion Mechanism (PMM) test in calm water. Verification for grid convergence is also conducted according to state-of-the-art study. The predicted turning trajectory and rolling angle of the S175 containership in regular waves using CFD results show better agreement with experiment data than empirical formula results. Furthermore, it has been demonstrated that this model is also capable of predicting the ship motion in regular waves with practical accuracy. And the effects of the wave frequency, wave height are investigated consequently base on numerical simulation results.
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Ivanovs, Viktors, und Pavels Gavrilovs. „Analysis and investigation on defects - delamination and spalling of metal on rolling surface of rail head under code X 10.1“. In 22nd International Scientific Conference Engineering for Rural Development. Latvia University of Life Sciences and Technologies, Faculty of Engineering, 2023. http://dx.doi.org/10.22616/erdev.2023.22.tf016.
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One of the main defects in rail steel is a defect on the rolling surface of the rail head. A sign of the defect appearance is delamination and spalling of the metal on the rolling surface. The development of this type of defect to a length of more than 25 mm and a depth of more than 4 mm requires a decrease of the train speed up to 70 km·h-1, and with a depth of more than 8 mm - to 25 km·h-1. Reducing the speed significantly affects the quality of service and railway performance. As a result, there is a disruption in the accuracy of train traffic, which subsequently leads to material costs for restoring the movement of trains at set speeds. The primary task of the study presented in this article is the collection and analysis of statistical information on the Latvian Railway defective rails in the period from 2011 to 2021. A secondary task is to investigate the causes of the appearance of rail defects under code X 10.1. The research process included: detection of these defects on the Latvian Railway using a modern ultrasonic flaw detector of the “RDM-24” type, determination of the metal hardness (EN 13674-1:2011 standard 350-390 HB) in the rail head and on the rolling surface using a certified modern device “Tinius O Olsen” Firmware Version 1.07, FH - 31 Series as well as the study of the chemical composition of the rail head using the optical emission analyzer PMI - Master PRO and determination of the microstructure of the metal in the rail head. At the final stage, to compare the results obtained in an independent certified laboratory, based on the results of the research to draw conclusions about the causes of this type of defect.
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Gupta, Vijay K., und Charles D. Eggleton. „A Numerical Method for Coupling Nano-Scale Molecular Binding With Mesoscale Cellular Deformation“. In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-13296.
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Cell adhesion plays a pivotal role in diverse biological processes, including inflammation and thrombosis. Changes in cell adhesion can be the defining event in a wide range of diseases, including cancer, osteoporosis, atherosclerosis, and arthritis. Cells are exposed constantly to hemodynamic/hydrodynamic forces and the balance between the dispersive hydrodynamic forces and the adhesive forces generated by the interactions of membrane-bound receptors and their ligands determines cell adhesion. The ultimate objective of our work is to develop software that can simulate the adhesion of cells colliding under hydrodynamic forces that can be used to investigate the complex interplay among the physical mechanisms and scales involved in the adhesion process. Here, we review the development of a multi-scale model combining Monte-Carlo models of molecular binding with the Immersed Boundary Method for cellular-hydrodynamic interactions. This model predicted for the first time that the rolling of more compliant cells is relatively smoother and slower compared to cells with stiffer membranes, due to increased cell-substrate contact area. At the molecular level, we show that the average number of bonds per cell as well as per single microvillus decreases with increasing membrane stiffness. The numerical model was modified to compare the effects of different kinetic models of molecular binding on cell rolling. Simulations predict that the catch-slip bond behavior and to a lesser extent bulk cell deformation are responsible for the shear threshold phenomenon. In bulk flow, shear rate has been shown to critically affect the kinetics and receptor specificity of cell-cell interactions. We are currently simulating the adhesion of two PMN cells in quiescent conditions and the exposing the cells to external pulling forces and shear flow in order to investigate the behavior of the nano-scale molecular bonds to forces applied at the cellular scale.
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Balint, Gheorghe, und Acsinte Alexandru. „THE USE OF COMPUTER INFORMATION TECHNOLOGY IN CREATING SPECIFIC PHYSICAL EDUCATION AND SPORTS THEORETICAL COURSES“. In eLSE 2013. Carol I National Defence University Publishing House, 2013. http://dx.doi.org/10.12753/2066-026x-13-220.
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Through its specific multiple uses, the electronic information technology constitutes an authentic current teaching means, producing a new revolution in education, compared to the one achieved by the invention of printing. Its apparition suggests a reconsideration of the didactic methods and strategies, of teaching style, of the projection and development of the instructive-educational act for the Physical Education in higher education. This is all the more evident if we take into consideration the combination: computer (means: information technology) - course in an electronic format (method) - individual activity (type of organization). When we are referring to the first way of inserting the computer in the curriculum, it is strictly associated to the notion of means; ulteriorly, it becomes a didactic strategy, being combined with other elements. The theoretical course model suggested in this paper constitutes an electronic document, with properties that are imposed by the current standards and demands of the IT users. In this sense, the electronic format desired for the structuring, accessibility, use, and management of the curricular content has been chosen according to the following criteria:  accessible and viable presentation;  immediate accessibility;  ease of use;  accessible Internet presence;  easy to find and encapsulate the content;  modularization and an arborescent structure of information. For this, the format Adobe Portable Document Format (PDF) has been chosen, which is very popular, very accessible, and tested over a long period of time by thousands of users. One of its main elements is the navigation tree (the arborescent structure - of dependencies) of the information (contents), called in the Reader: Bookmarks. Also, another main element in the presentation of information is the presentation panel for the actual content of the electronic course, allowing the specification of various attributes for the personalization of the e-course: page rolling, the physical position inside the e-course (the number of the current page, and the total number of pages), the visualizing format (the number of pages presented simultaneously). The concretion of the ideas presented above has been done through the creation of such a model of theoretical course: "The General Bases of Association Football," accessible at: http://cadredidactice.ub.ro/balintgheorghe/files/2012/12/bazele-generale-ale-fotbalului-3.pdf.
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Gupta, Vijay K., und Charles D. Eggleton. „A 3-D Computational Model of L-Selectin-PSGL-1 Dependent Homotypic Leukocyte Binding and Rupture in Shear Flow“. In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80862.
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Cell adhesion plays a pivotal role in diverse biological processes, including inflammation, tumor metastasis, arteriosclerosis, and thrombosis. Changes in cell adhesion can be the defining event in a wide range of diseases, including cancer, atherosclerosis, osteoporosis, and arthritis. Cells are exposed constantly to hemodynamic/hydrodynamic forces and the balance between the dispersive hydrodynamic forces and the adhesive forces generated by the interactions of membrane-bound receptors and their ligands determines cell adhesion. Therefore to develop novel tissue engineering based approaches for therapeutic interventions in thrombotic disorders, inflammatory, and a wide range of other diseases, it is crucial to understand the complex interplay among blood flow, cell adhesion, and vascular biology at the molecular level. In response to tissue injury or infection, polymorphonuclear (PMN) leukocytes are recruited from the bloodstream to the site of inflammation through interactions between cell surface receptors and complementary ligands expressed on the surface of the endothelium [1]. PMN-PMN interactions also contribute to the process of recruitment. It has been shown that PMNs rolling on activated endothelium cells can mediate secondary capture of PMNs flowing in the free blood stream through homotypic interactions [2]. This is mediated by L-selectin (ligand) binding to PSGL-1 (receptor) between a free-stream PMN and one already adherent to the endothelium cells [3]. Both PSGL-1 and L-selectin adhesion molecules are concentrated on tips of PMN microvilli [4]. Homotypic PMN aggregation in vivo or in vitro is supported by multiple L-selectin–PSGL-1 bondings between pairs of microvilli. The ultimate objective of our work is to develop software that can simulate the adhesion of cells colliding under hydrodynamic forces that can be used to investigate the complex interplay among the physical mechanisms and scales involved in the adhesion process. However, cell-cell adhesion is a complex phenomenon involving the interplay of bond kinetics and hydrodynamics. Hence, as a first step we recently developed a 3-D computational model based on the Immersed Boundary Method to simulate adhesion-detachment of two PMN cells in quiescent conditions and the exposing the cells to external pulling forces and shear flow in order to investigate the behavior of the nano-scale molecular bonds to forces applied at the cellular scale [5]. Our simulations predicted that the total number of bonds formed is dependent on the number of available receptors (PSGL-1) when ligands (L-selectin) are in excess, while the excess amount of ligands controls the rate of bond formation [5]. Increasing equilibrium bond length causes an increased intercellular contact area hence results in a higher number of receptor-ligand bonds [5]. Off-rates control the average number of bonds by modulating bond lifetimes while On-rate constants determine the rate of bond formation [5]. An applied external pulling force leads to time-dependent on- and off-rates and causes bond rupture [5]. It was shown that the time required for bond rupture in response to an applied external force is inversely proportional to the applied external force and decreases with increasing offrate [5]. Fig. 1 shows the time evolution of the total number of bonds formed for various values of NRmv (number of receptor) and NLmv (number of ligand). As expected, the total number of bonds formed at equilibrium is dependent on NRmv when NLmv is in excess. In this particular case study since two pairs (or four) microvilli each with NRmv are involved in adhesion hence the equilibrium bond number is approximately 4NRmv. It is noticed that for NRmv = 50, as we vary NLmv the mean value of the total number of bonds at equilibrium does not change appreciably. However, it can be noticed from Fig. 1 that for NRmv = 50, as the excess number of ligands (NLmv) increases there is a slight increase in the rate of bond formation due to the increase in probability of bond formation. Having developed confidence in the ability of the numerical method to simulate the adhesion of two cells that can form up to 200 bonds, we apply the method to study the effect of shear rate on the detachment of two cells. In particular, we first would like to establish the minimum shear rate needed for the two cells to detach for a given number of bonds between them. Fig. 2 shows the variation of force per bond at no rupture with number of bonds for various shear rates indicated. It is seen that at a given shear rate as the number of bonds increases the force per bond at no rupture decreases. This is attributed to the fact that force caused by shear flow is shared equally among the existing bonds. Further, it is seen that a given number of bonds as the shear rate increases the force per bond at no rupture increases. This is due to the fact that at a given number of bonds between the cells as we increase the shear rate the force caused by the flow increases hence the force per bond increases. We further notice that at shear rate = 3000 s−1 cells attached either by a single bond or by two bonds detach while they don’t for higher (> 2) number of bonds. This clearly demonstrate that there is a minimum shear rate needed to detach cells adhered by a given number of bonds. The higher the number of bonds, the higher the minimum shear rate for complete detachment of cells. For example, from Fig. 2 is it clear that for the cells adhered by two and five bonds the minimum shear rate needed for complete detachment of these two cells are 3000 s−1 and 6000 s−1, respectively.