Beam-beam-induced orbit effects at LHC

For high bunch intensities the long-range beam-beam interactions are strong enough to provoke effects on the orbit. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are presented in this paper.Comment: 5 pages, contribution to the ICFA Mini-Workshop on Beam-Beam Effects in Hadron Colliders, CERN, Geneva, Switzerland, 18-22 Mar 201

Development and lattice design of an ion-production ring for a beta-beam neutrino facility

Neutrino beams can be produced by accelerating beta active ions which will decay in a race track accelerator ring to produce intense focused neutrino beams. The production of these radioactive isotopes need special technology. One idea is to let a circulating low energy beam of 7Li or 6Li in a small production ring perform multiple traversals in a target to produce 8Li and 8B. The lattice of this production ring has to satisfy conditions to permit the radioactive isotope production but also to permit ionization cooling of the circulating beam. The lattice should be flexible and have margins for further optimization. This thesis describes the design of such a production ring lattice, having symmetry and flexibility. A simplified model of the wedge shaped target has been implemented, using results from Monte Carlo simulations, and is used as an element in the lattice to perform 6D tracking simulations of the cooling process. Tools for this simulation have been developed and tested

Stochastic modeling of geometric imperfections for buckling analysis of suction buckets

Recently, suction buckets have become a very prominent foundation for bottom fixed and floating offshore wind turbines. They are embedded with an installation force that stems from water evacuation inside the bucket. This internal negative pressure leads to a high risk of structural buckling. The buckling strength is significantly reduced by geometric imperfections. In previous work, equivalent geometric imperfection forms were introduced and the lower bound was evaluated. However, it has not yet been possible to identify a generally appropriate imperfection form. A probabilistic design approach based on realistic imperfections was not yet considered for suction buckets. Therefore, in this work, a stochastic modeling approach is introduced, which bases on measured data. The imperfection is decomposed to the half-wave cosine Fourier representation. Realizations of the imperfection pattern are generated by filtering white noise with the amplitude spectrum. They are then applied as out of plane deviations on a geometrically and materially nonlinear finite element model and evaluated. The resulting buckling pressure distribution can then be evaluated for different reliability levels. By considering more realistic imperfections and a plastic soil model, the buckling pressure increases by up to a factor of two compared to the conservative stress-based buckling approach

Untangle soil-water-mucilage interactions with 1H NMR Relaxometry

Mucilage is produced mainly at the root tips and has a high water holding capacity originating from highly hydrophilic gel-forming substances. The objective of the MUCILAGE project is to understand the mechanistic role of mucilage for the regulation of water supply for plants. Our subproject investigates the chemical and physical properties of mucilage as pure gel and in soil. 1H-NMR Relaxometry and PFG-NMR represent non-intrusive powerful methods for quantification of the water distribution and for monitoring of the water mobility in soil pores and gel phases. NMR relaxation of the protons in gel water differs from the one in pure water due to additional interactions with the gel matrix. Mucilage in soil leads to a hierarchical pore structure, consisting of the polymeric biohydrogel network surrounded by the surface of soil particles. The objective of our study is to distinguish in situ water in gel from pore water in a simplified soil system, and to determine quantitatively how the “gel effect” affects relaxation rate and water self-diffusion coefficient in porous systems. For this, we measured the variations of the water mobility in pure chia mucilage under different conditions by using 1H-NMR relaxometry and PFG-NMR. Using model soils, the signals coming from pore water and gel water were distinguished from each other. For this, we fitted the parameters of the equations describing 1H-NMR relaxation in porous systems with our experimental results, in order to describe how the presence of gel in soil affects 1H-NMR relaxation. Out of this knowledge, we proposed a method, which detects in situ the presence of mucilage in soil and characterizes several gel-specific parameters of the mucilage. Finally, we discussed the potential and limitations of 1H-NMR relaxometry for following natural swelling and shrinking processes of a natural biopolymer in soil

Experimental investigations on the fatigue resistance of automatically welded tubular X-joints for jacket support structures

The development within the offshore wind sector towards more powerful turbines combined with increasing water depth for new wind parks is challenging both the designer as well as the manufacturer of bottom fixed support structures. Besides XL-monopiles, the market developed an innovative and economic jacket support structure which is based on automatically manufactured tubular joints combined with standardized pipes. Besides the improvements for a serial manufacturing process the automatically welded tubular joints show a great potential in terms of fatigue resistance e.g. due to a smooth weld geometry without sharp notches. However, these benefits are not considered yet within the fatigue design process of automatically manufactured jacket substructures according to current standards due to the lack of suitable S-N curves. Therefore, 32 axial fatigue tests on single and double-sided automatically welded tubular X-joints have been performed to determine a new hot spot stress related S-N curve. Based on these constant amplitude fatigue tests a new S-N curve equal to a FAT 126 curve was computed which implicitly includes the benefits of the automatically welding procedure. © Published under licence by IOP Publishing Ltd

Is TNF-α a prognostic factor in patients with sepsis?

Objective: To determine tumor necrosis factor-α (TNF-α) levels in a prospective study in 58 hospitalized patients in a department of internal medicine (63 episodes, 29 in immunocompromised patients) during a 7-month period.Methods: Patients fulfilling the following criteria were included: clinical evidence of acute infection, temperature >38.2°C, tachycardia >90 beats/min, tachypnea >20 breaths/min. Samples were taken from day 1 up to day 13 after an infection was diagnosed, and TNF-α was determined by enzyme immunoassay.Results: In 29 episodes (46.0%) the infection was microbiologically documented. The median of the TNF-α levels in the Gram-negative episodes was significantly higher than that in the Gram-positive episodes (p = 0.002). Thirteen of 63 episodes (20.6%) had a fatal outcome. With respect to all measured values, the non-survivors had a significantly higher median of TNF-α levels than the survivors (p = 0.0001). There was, however, great interpatient and intrapatient variability in TNF-α levels; thus, no unequivocal correlation between TNF-α and outcome could be documented.Conclusions: Our data indicate that the influence of the infecting organism on TNF-α kinetics is less pronounced than that of the underlying disease

Processes governing development of ecotoxicity in clayey and silty soils incubated with olive mill wast water under different temperature and humidity conditions

Olive oil production generates olive mill wastewater (OMW) with a high content in nutrients and phenolic substances. Its application to soil could be a cost-effective solution for recycling. However, the degree of toxic effects of OMW on soil biota is widely unknown and has to be considered when searching for adisposal strategy. The objective of this study was to understand the degradation process of OMW organic matter and its influence on toxic effects as well as soil properties. We hypothesized that OMW toxicity decreases with degradation of its phenolic components. A higher soil biological activity was expected to increase degradation. We incubated a clayey soil and a silty soil with OMW for 60 days under conditions typical for this region in order to simulate the application during various seasons (winter, spring, summer dry, summer wet). Soil respiration, pH, electrical conductivity, total phenolic content as well as anion and cation content, specific ultraviolet absorbance at 254 nm and dissolved organic carbon were measured at ten points of time during incubation. Soils and methanolic soil extracts were tested for ecotoxicity using Lepidium sativum germination and Folsomia candida egg hatching rate. The degradation and transformation of OMW-organic matter was stronger under warm and humid conditions than under cold and dry conditions. It was furthermore enhanced in the clayey soil compared to the silty soil. Most severe ecotoxicological effects were found under summer dry conditions while spring as well as summer wet conditions led to a fast recovery of both germination and hatching. However, the silty soil did not recover to preapplication levels. In the clayey soil, germination parameter were higher than in control after around 30 days suggesting a fertilizing effect. Effects in methanol extracts were higher in all soils and climatic scenarios. Therefore, remobilization of OMW derived toxic compounds has to be considered on a long-term scale. Egg hatching as most sensitive life-cycle parameter of Folsomia candida showed also the same relation to climatic conditions and soil type but was more robust to OMW compared to Lepidium sativum. Environmental conditions as well as soil type are key factors determining degradation of OMW organic matter and OMW derived ecotoxicity. Therefore, spring application (warm and wet) of OMW seems to be a compromise with regard to OMW recycling, OMW occurrence in winter and farmer considerations

Optimization-based calibration of hydrodynamic drag coefficients for a semisubmersible platform using experimental data of an irregular sea state

For the simulation of the coupled dynamic response of floating offshore wind turbines, it is crucial to calibrate the hydrodynamic damping with experimental data. The aim of this work is to find a set of hydrodynamic drag coefficients for the semisubmersible platform of the Offshore Code Comparison Collaboration, Continuation, with Correlation and unCertainity (OC6) project which provides suitable results for an irregular sea state. Due to the complex interaction of several degrees of freedom (DOF), it is common to calibrate drag coefficients with the time series of decay tests. However, applying these drag coefficients for the simulation of an irregular sea state results in misprediction of the motions. By using numerical optimization, it is possible to calibrate multiple drag coefficients simultaneously and effectively, while also considering several DOF. This work considers time series of structural displacements from wave tank tests of the OC6 project and from simulations of the same load cases in OpenFAST. Results are transferred into the frequency domain and the deviation between power spectral densities of surge, pitch and heave from experiment and numerical simulation is used as an objective function to obtain the best fitting drag coefficients. This novel numerical optimization approach enables finding one set of drag coefficients for different load cases, which is a major improvement compared to decay-test-tuned drag coefficients. © Published under licence by IOP Publishing Ltd

Multi-site H-bridge breathers in a DNA--shaped double strand

We investigate the formation process of nonlinear vibrational modes representing broad H-bridge multi--site breathers in a DNA--shaped double strand. Within a network model of the double helix we take individual motions of the bases within the base pair plane into account. The resulting H-bridge deformations may be asymmetric with respect to the helix axis. Furthermore the covalent bonds may be deformed distinctly in the two backbone strands. Unlike other authors that add different extra terms we limit the interaction to the hydrogen bonds within each base pair and the covalent bonds along each strand. In this way we intend to make apparent the effect of the characteristic helicoidal structure of DNA. We study the energy exchange processes related with the relaxation dynamics from a non-equilibrium conformation. It is demonstrated that the twist-opening relaxation dynamics of a radially distorted double helix attains an equilibrium regime characterized by a multi-site H-bridge breather.Comment: 27 pages and 10 figure

How does particulate organic matter (POM) swelling affect soil -water interactions and soil structural stability on different scales?

Particulate organic matter (POM), root mucilage and synthetic polymers are swellable polymeric substances (“hydrogels”) which form a three-dimensional polymer network between soil particles. On the one hand, hydrogels can alter soil hydrological properties via their strong influence on water holding capacity and soil wettability. On the other hand, it has been recently shown that the presence of swollen hydrogel structures between soil particles can significantly contribute to soil structural stability. However, until now, only model polymer hydrogels have been used, and the findings still need to be transferred to soils which contain natural swellable organic substances. In this study, we investigated how the swelling of different POM fractions in soil contributes to soil-water-hydrogel interactions and to soil structural stability on different scales. We assumed that the swelling of easily available inter-aggregate POM (frPOM) and occluded intra-aggregate POM (iPOM) differ in their contribution to soil structural stability. For this purpose, we investigated the structural stability and soil-water interactions of a silty sand soil in a 2x2 nested design comprising tilled and non-tilled as well as compost-fertilized and non-fertilized sub-treatments. POM fractions were isolated by soil density fractionation and subsequently characterized for their swelling and water binding properties. Soil-water interactions in terms of water distribution and water mobility were assessed by one- and two-dimensional 1H-NMR relaxometry and pulsed-field-gradient (PFG) NMR. Results from 1H‑NMR measurements were linked with soil structural stability measurements conducted on the micro- and macroscale using soil rheology, wet sieving and crushing tests. On the micro- and macroscale, soil structural stability was higher for compost-fertilized samples than for non-fertilized with different effects of tillage. This was especially related to the presence of frPOM- and iPOM-associated water which revealed a significantly higher viscosity than mineral pore water. On the microscale, frPOM showed the highest contribution to soil structural stability, whereas iPOM predominantly stabilized the soil structure on the macroscale. The relationships suggest that the spatial location and hence the swellability of organic structures in soil could explain the nature of hydrogel-induced soil structural stability