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101.
Matthias Heymann 《NTM》2009,17(2):171-197
Constructing Climate. From Classical Climatology to Modern Climate Research
Both climate researchers and historians of climate science have conceived climate as a stable and well defined category. This
article argues that such a conception is flawed. In the course of the 19th and 20th century the very concept of climate changed
considerably. Scientists came up with different definitions and concepts of climate, which implied different understandings,
interests, and research approaches. Understanding climate shifted from a timeless, spatial concept at the end of the 19th
century to a spaceless, temporal concept at the end of the 20th. Climatologists in the 19th and early 20th centuries considered
climate as a set of atmospheric characteristics associated with specific places or regions. In this context, while the weather
was subject to change, climate remained largely stable. Of particular interest was the impact of climate on human beings and
the environment. In modern climate research at the close of the 20th century, the concept of climate lost its temporal stability.
Instead, climate change has become a core feature of the understanding of climate and a focus of research interests. Climate
has also lost its immediate association with specific geographical places and become global. The interest is now focused on
the impact of human beings on climate. The paper attempts to investigate these conceptual shifts and their origins and impacts
in order to provide a more comprehensive perspective on the history of climate research. 相似文献
102.
Measurement of Helium Leakage Rates through Closures of Dangerous Goods Packagings for the Assessment of Potentially Explosive Mixtures in Freight Containers 下载免费PDF全文
Eva Schlick‐Hasper Oliver Seidler Thomas Goedecke Matthias Kraume 《Packaging Technology and Science》2015,28(11):959-985
The objective was to find out whether an explosive atmosphere can be created in a freight container by gaseous leakage flow of vapour‐air‐mixture through leaks in the closures of dangerous goods packagings filled with hazardous liquids. Because of high temperatures during intercontinental carriage, there is a gauge pressure in the free vapour phase inside the packagings which can cause a gaseous leakage flow. Two different methods were applied: Helium limit leakage rates for 23 quantitatively important hazardous liquids concerning their lower explosion limit (LEL) were calculated for a worst case transport scenario (Method 1). Helium leakage rates of five closure types of dangerous goods packagings with volumes of approximately 6 l were measured using the pressure technique by accumulation (Method 2). All types of closures of steel packagings were uncritical. The maximum measured leakage was 33% of the limit leakage rate. The leakage rates of screw closures of plastic jerricans can exceed the LEL if there are production‐related patterns such as non‐concentricity of the closures and flashes on the neck. Especially for plastic packagings it is important to minimize gaseous leakage flow, because an explosive atmosphere can also be reached by permeation of the individual filling substance or by a combination of both effects. For the assessment of potentially explosive mixtures in freight containers, both mass transfer mechanisms have to be taken into account. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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105.
Matthias F. Groh Alexander Wolff Matthias A. Grasser Michael Ruck 《International journal of molecular sciences》2016,17(9)
Ionic liquids (ILs) have been proven to be valuable reaction media for the synthesis of inorganic materials among an abundance of other applications in different fields of chemistry. Up to now, the syntheses have remained mostly “black boxes”; and researchers have to resort to trial-and-error in order to establish a new synthetic route to a specific compound. This review comprises decisive reaction parameters and techniques for the directed synthesis of polyions of heavy main-group elements (fourth period and beyond) in ILs. Several families of compounds are presented ranging from polyhalides over carbonyl complexes and selenidostannates to homo and heteropolycations. 相似文献
106.
本文采用大涡模拟(LES)的方法研究了在基于外壳直径的雷诺数为9.36×105条件下5叶片的轴流式风扇的流动特性,并且着重分析了叶尖泄漏的流动现象。本文使用了基于有限体积法和分层笛卡尔网格的可压流求解器进行数值计算,并应用了体积守恒的切割网格方法处理风扇几何结构的浸入式边界。同时开发了用于笛卡尔网格的旋转周期性边界条件,这样只需分析由2.5亿网格构造的包含一片叶片的72°区域。该研究首先对网格质量进行了分析,之后讨论了瞬态和时均流场的特性,并与使用RANS的5叶片模拟结果进行了对比。RANS和LES模拟结果的主要不同之处体现在叶尖泄漏涡尾流中的湍流动能。本文进而研究了叶尖间隙对叶尖泄漏涡的影响。研究表明,间隙的大小会影响叶尖泄漏涡的大小形状。此外,间隙中更多的分离现象和反向旋转涡会导致较低的湍流动能。 相似文献
107.
Wolfram Witte Daniel Abou‐Ras Karsten Albe Gottfried H. Bauer Frank Bertram Christian Boit Rudolf Brüggemann Jürgen Christen Jens Dietrich Axel Eicke Dimitrios Hariskos Matthias Maiberg Roland Mainz Max Meessen Mathias Müller Oliver Neumann Thomas Orgis Stefan Paetel Johan Pohl Humberto Rodriguez‐Alvarez Roland Scheer Hans‐Werner Schock Thomas Unold Alfons Weber Michael Powalla 《Progress in Photovoltaics: Research and Applications》2015,23(6):717-733
The gallium gradient in Cu(In,Ga)Se2 (CIGS) layers, which forms during the two industrially relevant deposition routes, the sequential and co‐evaporation processes, plays a key role in the device performance of CIGS thin‐film modules. In this contribution, we present a comprehensive study on the formation, nature, and consequences of gallium gradients in CIGS solar cells. The formation of gallium gradients is analyzed in real time during a rapid selenization process by in situ X‐ray measurements. In addition, the gallium grading of a CIGS layer grown with an in‐line co‐evaporation process is analyzed by means of depth profiling with mass spectrometry. This gallium gradient of a real solar cell served as input data for device simulations. Depth‐dependent occurrence of lateral inhomogeneities on the µm scale in CIGS deposited by the co‐evaporation process was investigated by highly spatially resolved luminescence measurements on etched CIGS samples, which revealed a dependence of the optical bandgap, the quasi‐Fermi level splitting, transition levels, and the vertical gallium gradient. Transmission electron microscopy analyses of CIGS cross‐sections point to a difference in gallium content in the near surface region of neighboring grains. Migration barriers for a copper‐vacancy‐mediated indium and gallium diffusion in CuInSe2 and CuGaSe2 were calculated using density functional theory. The migration barrier for the InCu antisite in CuGaSe2 is significantly lower compared with the GaCu antisite in CuInSe2, which is in accordance with the experimentally observed Ga gradients in CIGS layers grown by co‐evaporation and selenization processes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
108.
Gerhard Heise Andreas Brner Marcel Dickmann Marina Englmaier Andreas Heiss Matthias Kemnitzer Jan Konrad Regina Moser Jrg Palm Helmut Vogt Heinz P. Huber 《Progress in Photovoltaics: Research and Applications》2015,23(10):1291-1304
In this paper, we present the selective structuring of all three patterns (P1, P2 and P3) of a monolithic interconnection of CIS (Cu(In,Ga)(S,Se)2) thin film solar cells by picosecond laser pulses at a wavelength of 1064 nm. We show results for single pulse ablation threshold values and line scribing of molybdenum films on glass (P1), CIS on molybdenum (P2) and zinc oxide on CIS (P3). The purposes of these processes are the p‐type isolation (P1), cell interconnect (P2) and n‐type isolation (P3), which are required for complete cell architecture. The half micron thick molybdenum back electrode can be structured with a process speed of more than 15 m/s at about 15 W average power without detectable residues and damage by direct induced laser ablation from the back side (P1). The CIS layer can be structured selectively down to the molybdenum at process speeds up to 1 m/s at about 15 W average power, due to the precision of direct laser ablation in the ultrashort pulse regime (P2). The ZnO front electrode layer is separated by clean trenches with straight side walls at process speeds of up to 15 m/s at about 10 W average power, as a result of indirect induced laser ablation (P3). A validation of functionality of all processes is demonstrated on CIS solar cell modules (30 × 30 cm2). By replacing one state‐of‐the‐art process by a picosecond laser process at a time, solar efficiencies could be increased for P1 and P2 and stayed on a similar level for P3. After an optimization of the patterning processes in the R&D pilot line of AVANCIS, we achieved a new record efficiency for an all‐laser‐patterned CIS solar module: 14.7% as best value for the aperture area efficiency of a 30 × 30 cm2 sized CIS module was reached. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
109.
Jürgen Allwohn Martin Brumm Gernot Frenking Matthias Hornivius Werner Massa Friedrich W. Steubert Sigrid Wocadlo 《Advanced Synthesis \u0026amp; Catalysis》1993,335(6):503-514
Synthesis and Conformational Analysis of Pyranophanones and Pyrylophanium Compounds with Intraannular Substituents The synthesis of [3.3]dithiapyranophanone 6 and 11 is accomplished by use of the two-components-dilution-principle. Pyrolysis of their bis(sulfones) 7 and 12 gives the [2.2]pyranophanones 8 , 9 and 13 . Under preservation of conformation the intraannular carbonyl-function is used for the synthesis of methylpyranophanoles 14 , 16 and 17 . The synthesis of pyrylophanium compounds 15 and 18 is possible by elimination in trifluoroacetic acid. 6 exhibits anti-conformation within its crystal-structure and like 7 reveals temperature-dependent behavior in solution. Using 6 as an example, a combination of 13C-NMR-spectroscopy, forcefield-calculation and computer-simulation is applied for the first time to give evidence for molecular-dynamic processes of cyclophanes. 8 and 9 are the syn- and anti-conformers of the desired product, as shown by X-ray structural analysis. 13 reveals anti-conformation within its crystal structure as well as in solution. The conformational analysis of other new phanes described here is based on the 1H-NMR-spectra of these pyrolysis products. As expected the intraannular substituents of Pyrylophanium-lons 15 and 18 show the characteristic upfield-shift within their 1H-NMR-spectra. 相似文献
110.