Numerical Modeling of Pulsed Raman Fiber Converters at 2 $mu{hbox {m}}$

Theoretical modeling of stimulated Raman scattering (SRS) in fibers is presented for the near-infrared band around 2 mum, where pump and Stokes wave have different absorption. This model takes into account amplified spontaneous emission (ASE), SRS towards Stokes and anti-Stokes waves, absorption of the Raman medium and Rayleigh backscattering in fibers. Depending on the fiber configuration, this model includes the cavity parameters of either external or internal mirrors at the fiber ends. Input parameters are, among others, temporal profiles of the pump radiation, absorption, and gain curve of the Raman medium. The model agrees well with experimental results obtained with a GeO₂ doped core fiber pumped by a pulsed and tunable Tm:silica fiber laser emitting around 2 mum.     

Assessing physical activity in the daily life of cystic fibrosis patients

Physical Activity (PA) plays an important role in the health and quality of life of cystic fibrosis (CF) patients, but little is known about their PA in daily living. With the use of accelerometers it is now possible to monitor activity profiles in detail. The goals of this study are to assess feasibility and acceptance of a longer-term use of accelerometers in daily living in CF patients, study the possibility of detecting changes in PA in relation to the patients’ clinical state and compare the findings between a CF and an age-matched healthy control group. We asked 15 CF patients to wear two accelerometers for 21 days and fill in a diary. Ten of them (age 21 to 40, mean 29.5 years) participated and delivered data that could be evaluated. We also recruited 10 age-matched control subjects. Data was processed for calculating usage time and features extracted to construct models of activity. The younger patients, particularly females, were concerned with fashion and style and considered wearing the sensors a challenge. Overall, the compliance of patients with CF seemed to be lower than reported for elder subjects in the literature. Time-series analysis of the data indicated characteristic patterns of PA over time, provided that data pre-processing and noise-filtering had been optimized. Further studies have to assess whether the continuous recording of PA yields additional clinical information in CF and in particular, whether it is possible to detect or even predict exacerbations in patients with CF or other diseases.     

Recommendations in a heterogeneous service environment

This paper presents novel algorithms which are able to generate recommendations within a heterogeneous service environment. In this work explicitly set preferences as well as implicitly logged viewing behavior are employed to generate recommendations for Digital Video Broadcast (DVB) content. This paper also discusses the similarity between the DVB genres and YouTube categories. In addition it presents results to show the comparison between well known collaborative filtering methods. The outcome of this comparison study is used to identify the most suitable filtering method to use in the proposed environment. Finally the paper presents a novel Personal Program Guide (PPG), which is used as a tool to visualize the generated recommendations within a heterogeneous service environment. This PPG is also capable of showing the linear DVB content and the non-linear YouTube videos in a single view.     

Influence of copper on the microstructure of sol–gel titanium oxide nanotubes array

The effect of copper addition in the microstructure of sol–gel titanium oxide (TiO₂) supported on anodic aluminum oxide (AAO) membranes is reported. Two deposition methods based on immersion and flow techniques were used for the coating of the porous AAO membrane. Copper-free membranes were studied as a function of different ratios of H⁺/Ti, H₂O/Ti, selecting the most appropriate for the sensitization with copper. For copper-doped TiO₂ arrays, the presence of copper causes the reduction of grain size and enhances titania deposition inside the AAO pores, although no clear tendency with copper content was found. The formation of copper-doped titania nanotubes was validated after dissolving the AAO membranes, finding a deposition-dependent stability in the Cu-doped materials. Titania and Cu-doped titania nanotubes analyzed as colloidal solutions show band gaps substantially shifted to the red in comparison to the direct band gap of near-spherical colloidal materials. These arrays are important for photocatalysis and for the development of third generation photovoltaic devices.     

Hot-wire ignition of ethanol–oxygen hydrothermal flames

The forced ignition experiments conducted in a novel high pressure hydrothermal spallation drilling pilot plant with a Ni/Cr-60/15 coiled wire are presented here. A water–ethanol mixture is used as fuel and gaseous oxygen as oxidation agent. The ignition characteristics of the combustible mixture are analyzed at 260 bar and for temperatures crossing its pseudo-critical point. The influence of the bulk temperature, the fuel composition and the flow conditions on the forced ignition is shown.     

THERMALLY INDUCED VIBRATIONS OF COMPOSITE BEAMS WITH INTERLAYER SLIP

Thermally excited vibrations of composite viscoelastic two-layer beams with interfacial slip are analyzed. Geometrically linearized conditions are considered, and the Bernoulli-Euler hypothesis is applied to each layer. At the interface a linear viscoelastic slip law is assigned. The resulting sixth-order initial boundary value problem of the deflection is solved in the time domain by separating the dynamic response in a quasistatic and a complementary dynamic portions. The quasistatic solution is determined in closed form, and the remaining complementary dynamic part is approximated by a truncated modal series that exhibits accelerated convergence. Numerical results are obtained for single-span composite beams with interlayer slip by means of a time-stepping procedure based on the linear interpolation of the driving terms within the time intervals.     

Intrinsic isotopic C labelling of polyphenols

The intrinsic isotopic labelling of plants with ¹³CO₂ is an effective method to generate highly labelled compounds using photosynthesis and avoiding labour-intensive complex organic syntheses. In this study, the intrinsic isotopic labelling of polyphenols in parsley, spinach and peppermint is shown for the first time. The plants were grown in an atmosphere where ¹²CO₂ was replaced by ¹³CO₂, in order to generate highly labelled compounds. The total content of ¹³C as well as the individual polyphenols were analysed by Isotopic Ratio-MS and HPLC–Iontrap-MSⁿ.     

Starch derivatives with high degree of functionalization. III. Influence of reaction conditions and starting materials on molecular structure of carboxymethyl starch

Carboxymethyl starch (CMS) was prepared in a completely heterogeneous procedure in a methanol/water slurry activated with aqueous sodium hydroxide (45%, w/v) using monochloroacetic acid as the etherifying agent. The influence of the reaction conditions and the type of starting starch (amylose content and preactivation) was evaluated in regard to the formation of the main repeating units (i.e., unfunctionalized and mono‐, di‐, tri‐, and tetra‐O‐carboxymethylated) and the pattern of functionalization within the anhydroglucose units (AGU). The reproducible synthesis gave products with a maximal degree of substitution of CM groups (DS_CM) of 0.66, which was reached in a one‐step synthesis. Repeated carboxymethylation led to products with a DS_CM of 0.88. As revealed by means of HPLC analysis after complete acidic depolymerization, in any sample the mono‐O‐carboxymethylated glucose (mono‐O‐CMglc) was preferably present while the di‐O‐CMglc was formed to a very low extent only. The tri‐O‐CMglc was found in some samples while tetra‐O‐CMglc was not detected. The mole fractions determined did not follow the simple Spurlin statistic as shown for CM cellulose synthesized under comparable conditions. Within the carboxymethylated AGUs a preferred functionalization at position 2 was analyzed by means of ¹H‐NMR spectroscopy after hydrolytic chain degradation. Consequently, the CMS samples synthesized contained mainly 2‐mono‐O‐CM‐AGU. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2036–2044, 2001     

The virtual production simulation platform: from collaborative distributed simulation to integrated visual analysis

Computational simulations are used for the optimization of production processes in order to significantly reduce the need for costly experimental optimization approaches. Yet individual simulations can rarely describe more than a single production step. A set of simulations has to be coupled to each other to form a contiguous representation of a process chain. Eventually, simulated results have to be analyzed by domain experts to gather insight from the preformed computations. In this paper, we propose an IT infrastructure and software tools that aim at a rather non-intrusive way of coupling resources and domain expert’s knowledge to enable the collaborative setup, execution and analysis of distributed simulation chains. We illustrate the approach in the domain of materials processing. Beyond means originating from the domain of GRID computing for resource management, a data integration component assures semantic data integrity between the simulation steps and stores simulation data in an application independent way. Thus, we can transform this data into native formats for each simulation tool, and finally into a format that allows for contiguous visualizations and an intuitive, comprehensive analysis of complete simulated process chains.