Sussmann's orbit theorem and maps

A map between manifolds which matches up families of complete vector fields is a fiber bundle mapping on each orbit of those vector fields.Comment: 4 pages, no figure

The Critical Challenges from International High-Tech and Computer-Related Crime at the Millennium

The automotive industry stands in front of a great challenge, to decrease its impact on the environment. One important part in succeeding with this is to decrease the structural weight of the body structure and by that the fuel consumption or the required battery power. Carbon fibre composites are by many seen as the only real option when traditional engineering materials are running out of potential for further weight reduction. However, the automotive industry lacks experience working with structural composites and the methods for high volume composite manufacturing are immature. The development of a composite automotive body structure, therefore, needs methods to support and guide the conceptual work to improve the financial and technical results. In this thesis a framework is presented which will provide guidelines for the conceptual phase of the development of an automotive body structure. The framework follows two main paths, one to strive for the ideal material diversity, which also defines an initial partition of the body structure based on the process and material selection. Secondly, a further analysis of the structures are made to evaluate if a more cost and weight efficient solution can be found by a more differential design and by that define the ideal part size. In the case and parameter studies performed, different carbon fibre composite material systems and processes are compared and evaluated. The results show that high performance material system with continuous fibres becomes both more cost and performance effective compared to industrialised discontinuous fibre composites. But also that cycle times, sometimes, are less important than a competitive feedstock cost for a manufacturing process. When further analysing the manufacturing design of the structures it is seen that further partition(s) can become cost effective if the size and complexity is large enough.      QC 20140527</p

Surface texturing of CVD diamond assisted by ultrashort laser pulses

Diamond is a wide bandgap semiconductor with excellent physical properties which allow it to operate under extreme conditions. However, the technological use of diamond was mostly conceived for the fabrication of ultraviolet, ionizing radiation and nuclear detectors, of electron emitters, and of power electronic devices. The use of nanosecond pulse excimer lasers enabled the microstructuring of diamond surfaces, and refined techniques such as controlled ablation through graphitization and etching by two-photon surface excitation are being exploited for the nanostructuring of diamond. On the other hand, ultrashort pulse lasers paved the way for a more accurate diamond microstructuring, due to reduced thermal effects, as well as an effective surface nanostructuring, based on the formation of periodic structures at the nanoscale. It resulted in drastic modifications of the optical and electronic properties of diamond, of which “black diamond” films are an example for future high-temperature solar cells as well as for advanced optoelectronic platforms. Although experiments on diamond nanostructuring started almost 20 years ago, real applications are only today under implementation

Interference errors in infrared remote sounding of the atmosphere

International audienceMore and more profiles of atmospheric state parameters are being retrieved from remote soundings in the infrared spectral domain. Classical error analysis, which was originally applied to microwave sounding systems, distinguishes between "smoothing errors," "forward model errors," "forward model parameter errors," and "retrieval noise errors". We show that for infrared soundings "interference errors", which have not been treated up to now, can be significant. Interference errors originate from "interfering species" that introduce signatures into the spectral measurement which overlap with the spectral features used for retrieval of the target species. This is a frequent situation in infrared atmospheric spectra where the vibration-rotation bands of different species often overlap; it is not the case in the microwave region. This paper presents a full theoretical formulation of interference errors. It requires a generalized state vector including profile entries for all interfering species. This leads to a generalized averaging kernel matrix made up of classical averaging kernels plus here defined "interference kernels". The latter are used together with climatological covariances for the profiles of the interfering species in order to quantify the interference errors. To illustrate the methods we apply them to a real sounding and show that interference errors have a significant impact on standard CO profile retrievals from ground-based mid-infrared solar absorption spectra. We also demonstrate how to minimize overall error, which is a trade-off between minimizing interference errors and the smoothing error. The approach used in this paper can be applied to soundings of all infrared-active atmospheric species, which includes more than two dozen different gases relevant to climate and ozone. And this holds for all kind of infrared remote sounding systems, i.e., retrievals from ground-based, balloon-borne, airborne, or satellite spectroradiometers

Validation of ENVISAT/SCIAMACHY columnar CO by FTIR profile retrievals at the Ground-Truthing Station Zugspitze

International audienceCarbon monoxide vertical profile retrievals from ground-based solar FTIR measurements at the Permanent Ground-Truthing Station Zugspitze (47.42° N, 10.98° E, 2964 m a.s.l.), Germany are used to validate columnar CO retrieved from ENVISAT/SCIAMACHY spectra (WFM-DOAS version 0.4). The WFM-DOAS retrievals of CO include an empirical column scaling factor of 0.5. Therefore, not absolute column levels are validated, but the proper response of the SCIAMACHY retrievals to the atmospheric inter-annual variability is quantitatively assessed in comparison to the Zugspitze FTIR results. Although CO WFM-DOAS data for only 33 days are available up to now (data covering January?October 2003), it is possible to retrieve information on the CO annual cycle (?10% amplitude) in a statistically significant fit out of the scatter of the SCIAMACHY WFM-DOAS data. To obtain this, all pixels within a minimum radius of 2000 km around Zugspitze had to be averaged for each day

Technical Note: Interference errors in infrared remote sounding of the atmosphere

Classical error analysis in remote sounding distinguishes between four classes: &quot;smoothing errors,&quot; &quot;model parameter errors,&quot; &quot;forward model errors,&quot; and &quot;retrieval noise errors&quot;. For infrared sounding &quot;interference errors&quot;, which, in general, cannot be described by these four terms, can be significant. Interference errors originate from spectral residuals due to &quot;interfering species&quot; whose spectral features overlap with the signatures of the target species. A general method for quantification of interference errors is presented, which covers all possible algorithmic implementations, i.e., fine-grid retrievals of the interfering species or coarse-grid retrievals, and cases where the interfering species are not retrieved. In classical retrieval setups interference errors can exceed smoothing errors and can vary by orders of magnitude due to state dependency. An optimum strategy is suggested which practically eliminates interference errors by systematically minimizing the regularization strength applied to joint profile retrieval of the interfering species. This leads to an interfering-species selective deweighting of the retrieval. Details of microwindow selection are no longer critical for this optimum retrieval and widened microwindows even lead to reduced overall (smoothing and interference) errors. Since computational power will increase, more and more operational algorithms will be able to utilize this optimum strategy in the future. The findings of this paper can be applied to soundings of all infrared-active atmospheric species, which include more than two dozen different gases relevant to climate and ozone. This holds for all kinds of infrared remote sounding systems, i.e., retrievals from ground-based, balloon-borne, airborne, or satellite spectroradiometers