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Temporal and spatial variability of black carbon mass concentrations and size-resolved particle number concentrations in Germany ranging from city street to high Alpine environmentsSun, Jia 18 January 2022 (has links)
The German Ultrafine Aerosol Network (GUAN) has been continuously measuring the particle number size distribution (PNSD) and equivalent black carbon (eBC) mass concentration since 2009 at 17 atmospheric observatories in Germany, covering all environments from roadside to high-Alpine environments. GUAN provides us an opportunity to reduce the knowledge gaps about the spatio-temporal variation of sub-micrometer particles in different size ranges and eBC mass. These data are not only highly valuable for air pollution and health studies but also can help to reduce the uncertainties in the climate model predictions. With these long-term multi-site-category measurements, it was investigated for the first time how pollutant parameters interfere with spatial characteristics and site categories. Based on this first investigation, the long-term changes in size-resolved particle number concentrations (PNC) and eBC mass concentration were investigate to evaluate the effectiveness of the emission mitigation policies in Germany. The emission and pollutants near ground can be frequently transported to the free troposphere (FT) in the mountain areas. To identify if the decreased emissions at lower-altitudes have affected the aerosol loading in the aged, well-mixed FT air over Central Europe, the long-term trends in PNC and eBC mass concentration were analyzed for the FT and planetary boundary layer (PBL) conditions separately, at two high-Alpine observation sites. In summary, this dissertation aims to answer the following related scientific questions:
Q1: How do the sub-micrometer PNSD, PNC, and eBC mass concentration interfere with spatial characteristics and site categories? (First publication)
In the first publication (Sun et al., 2019), the spatio-temporal variability of aerosol parameters including PNSD, PNCs, and eBC mass concentration from the GUAN network were investigated for the period 2009−2014. Significant differences in the pollutant concentration were observed among various site categories. The six-year median value of sub-micrometer PNC (diameter range 20–800 nm) varies between 900 and 9000 cm−3, while median eBC mass concentration varies between 0.1 and 2.3 μg m-3 in 17 observation sites. PNCs in different size ranges were found in different spatial variabilities.
A cross-correlation between PNSD and eBC mass concentration was analyzed to detect the influence of anthropogenic sources for different site categories. The size-dependent spatial variability analysis of PNCs extracted three size intervals: a higher spatial variability size range 10–30 nm, a transition size range 30–100 nm and a lower spatial variability size range 100–800 nm. Based on the evaluated spatial variability, the measured parameters at various sites were clustered by a hierarchical clustering approach, which revealed different spatial clusters for “source-driven” and “long-range transport” parameters. This result suggests that the traditional “site category” (i.e. urban, and regional background, etc.) concerning mainly the influence of local sources cannot always catch the variation of aerosol particle mass or number concentrations. The dominant factors for various parameter are different, leading to different variability and spatial distribution. The result of spatial clustering offers a sound scientific base to compare pollutant parameters measured in different locations and environments.
By assessing the relationship between the measured parameters and geographical distance between different sites, the spatial variability of the aerosol parameters follows the “First Law of Geography” that everything is related to everything else, but near things are more related than distant things (Tobler, 1970). However, different parameters show different sensitivities on geographical distance. The analysis provides an important reference for setting up an observation network with a specific research purpose and is also useful for the regional scale dispersion models or land-use regression models.
Q2: How do the sub-micrometer PNSD, PNC, and eBC mass concentration change at a decadal scale? Have the implementations of emission mitigation policies affected the observed decadal trend? (Second publication)
In the second publication (Sun et al., 2020), long-term trends in atmospheric PNCs and eBC mass concentration for a 10 years period (2009–2018) were determined for 16 sites of the GUAN, ranging from roadside to high-Alpine. To ensure the data consistency for the trend detection, a thorough and detailed data quality check and data cleaning for the large GUAN dataset was performed. Statistically significant decreasing trends were found for 85% of the parameters and observation sites indicating an overall decreasing trend in sub-micrometer PNC (except N[10−30]) and eBC mass concentration all over Germany.
Comparing the trends of measured parameters with the long-term change in total emission, we proofed that the observed trends of PNCs and eBC mass concentrations were mainly due to the emission reduction. The detailed diurnal and seasonal trends in eBC mass concentration and PNCs further confirmed that the observed decreasing trends were largely owing to the reduced emissions such as traffic emission, residential emission, and industry emission, etc. Moreover, the inter-annual changes of meteorological conditions and long-range transport pattern were found not to be the main reason for the decreases in pollutant parameters. This study suggests that a combination of emission mitigation policies can effectively improve the air quality over large spatial scales such as Germany. Given the relative novelty of the long-term measurements (PNSD, eBC mass concentration) in a network such as GUAN, the results proved to be quite robust and comprehensive.
Q3: Have the decreased PNC and eBC mass concentration due to emission mitigation policies at the lower-altitudes affected the background air in lower FT over Central Europe? (Third publication)
In the third publication (Sun et al., 2021), the long-term change of the eBC mass concentration and size-resolved PNCs were determined and analyzed at two high Alpine stations for the period 2009-2018: Schneefernerhaus at mountain Zugspitze in Germany (ZSF, 2671 m a.s.l.) and Jungfraujoch in Switzerland (JFJ, 3580 m a.s.l.). The trend analysis was performed for the FT and PBL-influenced conditions separately, aiming to assess whether the reduced emissions at lower-altitudes over Central Europe can affect the background air in the lower FT on a large spatial scale.
The FT and PBL conditions at the two stations were segregated using the adaptive diurnal minimum variation selection (ADVS) method. The result showed that the FT condition in cold months is more prevalent than in warm months. Overall, the FT conditions frequency was ~25% and 6% in the cold and warm seasons at ZSF, respectively. At JFJ, the frequency of FT was ~45% and 10% in these two seasons, respectively.
The PNC and eBC mass concentration showed a statistically significant decrease during PBL time. The observed decreasing trends in eBC mass concentration in the PBL-influenced condition are well consistent with the reported trends in total BC emission in Germany and Switzerland. For the FT conditions, decreases in PNC and eBC mass concentration over the years was detected at both sites, suggesting the background PNC and eBC mass in the lower FT over Central Europe has decreased as well. The implementation of emission mitigation policies is the most decisive factor but the weather pattern change over Central Europe also has contributed to the decreasing trends in FT condition.:List of Figures ……………………………………………………………………………………………..I
List of Tables ..……………………………………………………………………………………………..I
Abbreviations .……………………………………………………………………………………………II
1. Introduction …………………………………………………………………………………………….1
1.1 Role of atmospheric sub-micrometer aerosol particles…...………………………………………...1
1.2 Measurement of sub-micrometer particle number size distribution, particle number concentration,
and eBC mass concentration…..……………………………………………….………………………….2
1.3 Previous long-term observations of PNSD, PNC, and eBC mass concentration…………………...4
1.4 Objectives...………………………………………………………………………………………….6
2. Data and Method…..……………………………………………………………………………………9
2.1 The German Ultrafine Aerosol Network (GUAN) …………………………………………………9
2.1.1 Measurement sites in GUAN…………………………………………………………………..10
2.1.2 Instrumental set-up.……….………………………………………………………….…………14
2.1.3 Quality assurance.………………………………………………………………………….……16
2.1.4 Data coverage…..………………………………………………………………………………..17
2.2. High-Alpine observatory Jungfraujoch (JFJ)……………………………………………………..18
2.2.1 Measurement site……….……………………………………………………………………….18
2.2.2 Instrumentation ..………………………………………………………………………………..19
2.3 Data analysis methods……………………………………………………………………………….19
2.3.1 Agglomerative hierarchical clustering….……………………………………………………...19
2.3.2 Customized Sen’s slope estimator…………………..…………………………………………...21
2.3.3 Generalized least-square regression and autoregressive bootstrap confidence intervals (GLS-
ARB)…………………………………………………………………………………………………21
2.3.4 Seasonal Mann-Kendal test…..………………….………………………………………………22
2.3.5 Back-trajectory classification method….……………………………………………………...24
3. Results and Discussion…..………………………………………………………………………….27
3.1 First publication….…………………………………………………………………………………..27
3.1.1 Variability of black carbon mass concentrations, sub-micrometer particle number concentrations and size distributions: results of the German Ultrafine Aerosol Network ranging from city street to
High Alpine locations……………………………………...………………………………………...27
3.1.2 Supporting information..……………………………………………………………………….41
3.2 Second publication…………………………………………………………………………………..45
3.2.1 Decreasing trends of particle number and black carbon mass concentrations at 16 observational
sites in Germany from 2009 to 2018…..…………………………………………………………..45
3.2.2 Supporting information...……………………………………………………………………….66
3.3 Third publication……………………………...……………………………………………………..75
3.3.1 Long-term trends of black carbon and particle number concentration in the lower free
troposphere in Central Europe…………………………………………………………………………75
3.3.2 Supporting information..…….……………………………………………………………….92
4. Summary and Conclusions..………………………………………………………………………… 95
5. Outlook….…………………………………………………………………………………………...99
Appendix A….………………………………………………………………………………………...100
Bibliography…………………………………………………………………………………………...101
Acknowledgements….…………………………………………………………………………………115
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Mechanistic studies of localized corrosion of Al alloys by high resolution in-situ and ex-situ probing techniquesDavoodi, Ali January 2007 (has links)
A multi-analytical approach based on in-situ and ex-situ local probing techniques was employed to investigate localized corrosion mechanisms of some aluminum alloys in chloride containing solutions, focusing on the influence of intermetallic particles (IMPs) in the alloys. In the EN AW-3003 alloy, SEM-EDS analysis revealed constituent and dispersoid IMPs. There are two types of constituent IMPs, with size ranging from 0.5 to several μm, and composition typically Al6(Fe,Mn) or Al12(Mn,Fe)3Si, respectively,having a Mn/Fe ratio of about 1:1. Fine dispersoids of 0.5 μm or less in size normally have the composition Al12Mn3Si1-2. Scanning Kelvin probe force microscopy (SKPFM measurements showed that the constituent IMPs have a higher Volta potential compared to the matrix, and the Volta potential difference increased with particle size, probably related to the composition of the IMPs. The SKPFM results also showed a Volta potential minimum in the boundary region adjacent to some larger IMPs. The open-circuit potential and electrochemical impedance spectroscopy measurements indicated local electrochemical activities occurring on the surface, and active-like dissolution in the acidic solutions, but a passive-like behavior in the near-neutral solutions. Infrared reflection-absorption spectroscopy measurements after exposure and thermodynamic calculations suggested the formation of mixtures of aluminum oxyhydroxide and acetate on the surface in acetic acid solutions. The formation and fraction of dominant species of the corrosion products depend on the pH of the solution, and aluminum chloride compounds may form at very low pH. Moreover, an integrated in-situ atomic force microscopy (AFM) and scanningelectrochemical microscopy (SECM) set-up was used to investigate the localized activities on the surface. With a dual mode probe, acting as both AFM tip and SECM microelectrode, concurrent topography and electrochemical current images were obtained on the same area of the surface. Numerical simulations of the SECM suggested a micrometer lateral resolution under favorable conditions and the ability to resolve μmsized active sites with a separation distance of about 3 μm or larger. The simulations were verified by SECM mapping of the aluminum alloys in the chloride solutions. The AFM/SECM measurements revealed enhanced cathodic activity on some larger IMPs and local anodic dissolution around larger IMPs. In-situ AFM monitoring confirmed preferential dissolution in the boundary region adjacent to some of these IMPs. The results elucidate the micro-galvanic effect and size effect of the IMPs during the initiation of localized corrosion of the Al alloys. Furthermore, differences in corrosion properties between EN AW-3003 and a newly developed Al–Mn–Si–Zr alloy were studied with a similar approach. Compared to EN AW-3003, the new alloy had a smaller number of particles with a large Volta potential difference relative to the matrix. In slightly corrosive solutions extensive localized dissolution and deposition of corrosion products occurred on EN AW-3003, whereas only a small number of corroding sites and “tunnel-like” pits occurred on the Al–Mn–Si–Zr alloy. The lower corrosion activity and the smaller tunnel-like pits resulted in lower material loss of the Al–Mn–Si–Zr alloy, which is beneficial for applications using a thin material. / QC 20100702
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A Study of the Selling Strategy of the Metrology-- Case Study of Coordinate Measuring MachineChen, Cheng-Tung 16 August 2011 (has links)
ABSTRACT(^ ¤å ºK n)
The mother of the industrial machinery industry, often regarded as a national benchmark assessment of industrial competitiveness, the traditional concept of the cutting and forming machine tools for the spindle, including optoelectronics, semiconductors, automobiles, 3C electronics and aerospace industries, the relevant production or processing equipment, all belong to this category. With the evolution of technology, increasingly stringent product quality requirements, such as the appearance of the size of the high precision requirements and the material surface, gradually the importance of testing equipment and manufacturing go hand in hand, on behalf of the state's technology industry is expected in the near The future will be an important assessment of industrial competitiveness indicators.
On the other hand, the mainland market after ten years of cross-strait exchange, itself played a significant change, from the early to the extreme dependence on imported equipment to produce the world-famous cottage products, no matter how the people of Taiwan to the mainland products exclusion, in the free under the natural law of market competition, the consumer market in Taiwan has long been filled with many mainland-made products. Their number and variety of the broad, deep penetration, simply makes hard to detect, and many exclusive products in the mainland business executives, the factory uses a lot of their own system of equipment are still unaware of the mainland, and even know, but also not find to alternative products. Indeed, many products have to meet the continent needs, these needs is not only reflected in the consumer goods market, is also rapidly spreading to the industrial market.
Most of the countries with advanced manufacturing technology in the world, more or less with metrology industry. Taiwan alone will not only have no metrology manufacturing base, and even the Taiwan metrology companies in , mainland China, the increasing decline in ability to survive, the market that introduced by the Taiwan factories in the past swallowed gradually and easily by the local vendors. Worry about the future of Taiwan metrology industry. If Taiwan metrology industry can not get a good position in the world, can we be famous just by create a brand?
Case is a company with more than 30 years of metrology sales background, in southern Taiwan. Because the relatively small market, it is difficult to obtain the dominant position of advantage. However, with the rise in the mainland market, the case company is full of many opportunities. This paper will research the sale strategy during these changeable situations.
Bisides, metrology includes wide range products, this paper choose Coordinate Measuring Machines (CMM) as the basis of the primary products, mainly because of higher prices, the level of broader considerations in business, relatively high barriers to entry, in addition, it also has many features quite representative of the industry's products.
Key words: Metrology, Coordinate Measuring Machines, CMM, hardness, surface roughness measuring instrument, roundness measuring instrument, the contour profile instrument, caliper, height gauge, optical flatness gauge, indicating scale, micrometer , microscopes , projectors , block gauge
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Phase-Contrast Imaging, Towards G2-less Grating Interferometry With Deep Silicon / Faskontrastavbildning, Mot G2-lös Gitterinterferometri med Djupt KiselBrunskog, Rickard January 2022 (has links)
Conventional phase-contrast imaging entails stepping an analyser grating across the detector to resolve the interference pattern caused by the x-rays after passing through a series of gratings in a so-called Talbot-Lau interferometer. However, the analyser grating in the interferometer poses a challenge, not only due to the machinery and alignment required but also due to each exposure delivering a dose to the subject. Another downside of the analyser grating is that whilst the phase-step length can be adjusted, the x-rays allowed through the grating depend on its slit-width ratio, which cannot be changed without changing the whole grating.This thesis evaluates if the analyser grating can be removed by instead using a deep silicon photon-counting detector which can determine the photon interaction position with an uncertainty of around one micrometre. It is concluded that such a high-resolution detector will not only be able to remove the need for an analyser grating and its associated challenges, but the results also imply a three-fold increase in the contrast-to-noise ratio when dose-matching the grating-based approach with the grating-less approach. Furthermore, the conventional absorption image, which is lost when using an analyser grating, will still be available using a high-resolution detector. Finally, the removal of the analyser grating shifts most of the system conditions to the source grating and the phase grating, making it possible to design a compact unit of the two gratings for integration into a CT scanner. / Konventionell faskontrast involverar att stega ett analysgitter över detektorn för att detektera interferensmönstret som skapas av röntgenstrålarna efter att de passerat genom en serie gitter i en så kallad Talbot-Lau interferometer. Analysgittret introducerar en utmaning, inte enbart på grund av maskineriet och kalibreringen som krävs, utan även då varje steg utsätter det röntgade föremålet för strålning. Ytterligare en begränsning är att även om längden på stegen kan justeras beror mängden röntgenstrålar som passerar genom analysgittret på gittrets slitsbredd, vilken inte går att ändra på utan att byta hela gittret.Den här uppsatsen utvärderar om analysgittret kan tas bort genom att istället använda en högupplöst fotonräknande djup kiseldetektor som har förmågan att uppskatta positionen av en fotoninteraktion inom en mikrometer. Slutsatsen är att en sådan detektor kommer att kunna ersätta analysgittret och resultaten tyder på en trefaldig ökning av contrast-to-noise ratio vid dosmatchning mellan metoden med analysgitter och metoden med en högupplöst detektor. Vidare behålls den konventionella absorptionsbilden då man använder en högupplöst detektor, någonting som annars går förlorat vid användandet av analysgittret. Slutligen skiftas de flesta villkoren på systemet till källgittret och fasgittret, vilket tyder på att en kompakt konstruktion av dessa två gitter skulle kunna integreras i en CT-skanner.
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