260 research outputs found
European freight vehicle running gear: Today's position and future demands
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugÀnglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The running gear of most of the rail freight vehicles in operation today tends to be built to very old designs. The running gear for new freight rolling stock and, in particular, new types of bogie must have significantly improved performance if they are to satisfy the demands of all the stakeholders associated with the railways. Improved performance in this context means reduced inspection time and brake manipulation time in marshalling yards, lower weight, lower noise emissions and lower lateral track forces. All this can be achieved by new designs of bogie running gear, at little extra first cost and at lower whole life cost
Wear and energy-saving freight bogie designs with rubber primary springs: principles and experiences
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugÀnglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The traditional radial steering bogie with swing hanger links is known to be track-friendly but heavy, and expensive in investment and maintenance costs. Whereas the actual bogies with longitudinal stiff axle guidance such as Y25 cause severe wear on wheels and rails in curves, and also develop high running resistance in curves. Bogies with rubbers springs like double rubber ring spring (DRRS), Leicht und LaermArm (LEILA) low weight and low noise, and Gigabox are a new feature with good behaviour in curves and on straight tracks. Good experience over many years with DRRS and 35 t axle load on the German Rheinisch Westfaelische Elektrizitaetswerke (RWE) coal line prove its benefits. For the new designs, LEILA and Gigabox, which are being introduced into the market now, even higher benefits can be demonstrated. The principle design features and the benefits regarding lateral track forces, wear, and traction resistance are evident. Also noise behaviour is an increasing demand for freight operation
Critical speed and limit cycles in the empty Y25-freight wagon
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugÀnglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.In this research, an empty freight wagon with Y25 bogies have been modelled. Non-linear creep forces with spin moment between wheel and rail have been used, and also all impacts and friction forces have been modelled. Non-linear equations of motion and kinematical constraints have been solved in time domain, and limit cycles, saddle nodes, and critical speeds have been shown. Both primary and secondary hunting can be seen in the responses of the wagons. The relation between frequency of oscillations and speed can be seen, also, there are chaotic oscillations. Results show that stiffness in impacts affects calculation time and limit cycles
Effect of suspension system in the lateral stability of railway freight trucks
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugÀnglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.In the current research an empty freight wagon with BA652 and an old BA661 bogies have been modelled. Non-linear creep forces with spin moment between wheel and rail have been used and also all impacts and friction forces have been modelled. The characteristics of primary suspension systems for BA652 and an old BA661 have been evaluated by means of test. Non-linear equations of motions and kinematical constraints have been solved in time domain and limit cycles have been showed. Both primary and secondary hunting can be seen in responses of wagon. For BA652 there are non-linear and linear critical speeds and also saddle nodes but for old BA661 the situation is too critical and the system can oscillate in very low speeds
Evolutionary optimization of optical antennas
The design of nano-antennas is so far mainly inspired by radio-frequency
technology. However, material properties and experimental settings need to be
reconsidered at optical frequencies, which entails the need for alternative
optimal antenna designs. Here a checkerboard-type, initially random array of
gold cubes is subjected to evolutionary optimization. To illustrate the power
of the approach we demonstrate that by optimizing the near-field intensity
enhancement the evolutionary algorithm finds a new antenna geometry,
essentially a split-ring/two-wire antenna hybrid which surpasses by far the
performance of a conventional gap antenna by shifting the n=1 split-ring
resonance into the optical regime.Comment: Also see Supplementary material, as attached to the main pape
NLO QCD and electroweak corrections to W+\gamma\ production with leptonic W-boson decays
We present a calculation of the next-to-leading-order electroweak corrections
to W+\gamma\ production, including the leptonic decay of the W boson and taking
into account all off-shell effects of the W boson, where the finite width of
the W boson is implemented using the complex-mass scheme. Corrections induced
by incoming photons are fully included and find particular emphasis in the
discussion of phenomenological predictions for the LHC. The corresponding
next-to-leading-order QCD corrections are reproduced as well. In order to
separate hard photons from jets, a quark-to-photon fragmentation function a la
Glover and Morgan is employed. Our results are implemented into Monte Carlo
programs allowing for the evaluation of arbitrary differential cross sections.
We present integrated cross sections for the LHC at 7TeV, 8TeV, and 14TeV as
well as differential distributions at 14TeV for bare muons and dressed leptons.
Finally, we discuss the impact of anomalous WW\gamma\ couplings.Comment: 33 pages latex, 16 figures, typos in Table 1 correcte
Automated Image Analysis of Transmission Electron Micrographs: Nanoscale Evaluation of Radiation-Induced DNA Damage in the Context of Chromatin
Background: Heavy ion irradiation (IR) with high-linear energy transfer (LET) is characterized by a unique depth dose distribution and increased biological effectiveness. Following high-LET
IR, localized energy deposition along the particle trajectories induces clustered DNA lesions, leading
to low electron density domains (LEDDs). To investigate the spatiotemporal dynamics of DNA repair
and chromatin remodeling, we established the automated image analysis of transmission electron
micrographs. Methods: Human fibroblasts were irradiated with high-LET carbon ions or low-LET
photons. At 0.1 h, 0.5 h, 5 h, and 24 h post-IR, nanoparticle-labeled repair factors (53BP1, pKu70,
pKu80, DNA-PKcs) were visualized using transmission electron microscopy in interphase nuclei to
monitor the formation and repair of DNA damage in the chromatin ultrastructure. Using AI-based
software tools, advanced image analysis techniques were established to assess the DNA damage
pattern following low-LET versus high-LET IR. Results: Low-LET IR induced single DNA lesions
throughout the nucleus, and most DNA double-strand breaks (DSBs) were efficiently rejoined with no
visible chromatin decondensation. High-LET IR induced clustered DNA damage concentrated along
the particle trajectories, resulting in circumscribed LEDDs. Automated image analysis was used
to determine the exact number of differently sized nanoparticles, their distance from one another,
and their precise location within the micrographs (based on size, shape, and density). Chromatin
densities were determined from grayscale features, and nanoparticles were automatically assigned to
euchromatin or heterochromatin. High-LET IR-induced LEDDs were delineated using automated
segmentation, and the spatial distribution of nanoparticles in relation to segmented LEDDs was
determined. Conclusions: The results of our image analysis suggest that high-LET IR induces chromatin relaxation along particle trajectories, enabling the critical repair of successive DNA damage.
Following exposure to different radiation qualities, automated image analysis of nanoparticle-labeled
DNA repair proteins in the chromatin ultrastructure enables precise characterization of specific DNA
damage patterns
CD8+ and Regulatory T cells Differentiate Tumor Immune Phenotypes and Predict Survival in Locally Advanced Head and Neck Cancer
Background: The tumor immune status âinflamedâ, âimmune excludedâ, and âdesertâ might serve as a predictive parameter. We studied these three cancer immune phenotypes while using a simple immunohistochemical algorithm. Methods: Pre-treatment tissue samples of 280 patients with locally advanced HNSCC treated with radiochemotherapy were analyzed. A double staining of CD8+ cytotoxic T cells (CTL) and FoxP3+ (Treg) was performed and the cell density was evaluated in the intraepithelial and stromal compartment of the tumor. Results: The classification of tumors as âimmune desertâ when stromal CTL were †50 cells/mm2, âinflamedâ when intraepithelial CTL were > 500 cells/mm2, and as âexcludedâ when neither of these definitions met these cut off values allowed the best discrimination regarding overall survival. These groups had median OS periods of 37, 61, and 85 months, respectively. In âimmune desertâ and âimmune excludedâ tumors high Treg tended to worsen OS, but in âinflamedâ tumors high Treg clearly improved OS. Conclusions: We propose that, in locally advanced HNSCC, the tumor immune state âinflamedâ, âimmune excludedâ, and âimmune desertâ can be defined by intraepithelial and stromal CTL. Tregs can further subdivide these groups. The opposing effects of Tregs in the different groups might be the reason for the inconsistency of Tregs prognostic values published earlier
Generalized helicity formalism, higher moments, and the BâKJK(âKÏ)ÂŻÂŻÂŻâ1â2 angular distributions
We generalise the Jacob-Wick helicity formalism, which applies to sequential
decays, to effective field theories of rare decays of the type . This is achieved by reinterpreting
local interaction vertices as a coherent sum of processes mediated
by particles whose spin ranges between zero and . We illustrate the
framework by deriving the full angular distributions for and for the complete
dimension-six effective Hamiltonian for non-equal lepton masses. Amplitudes and
decay rates are expressed in terms of Wigner rotation matrices, leading
naturally to the method of moments in various forms. We discuss how higher-spin
operators and QED corrections alter the standard angular distribution used
throughout the literature, potentially leading to differences between the
method of moments and the likelihood fits. We propose to diagnose these effects
by assessing higher angular moments. These could be relevant in investigating
the nature of the current LHCb anomalies in as well as angular observables in .Comment: identical to version appeared in PRD. typo in Eq below C.9 corrected,
includes Mathematica notebook with angular distribution same as v
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