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Raman spectra from three different binary gasoline-ethanol blends (with ratios 95:5, 90:10, and 85:15) have been obtained by using a low-cost, frequency precise Fourier-transform Raman spectrometer (FT-Raman) prototype. The spectral information is presented in the range of 0 to 3500 cm-1 with a resolution of 1.66 cm-1, which is greater than the required for most liquid and solid chemical samples. This set-up delivers spectral information about the sample with a reduced spectral deviation compared to theoretical values (less than 0.4 cm-1 without compensation for instrumental response). The robust and highly fexible FT-Raman prototype presented for the spectral analysis, consisting mainly of a Michelson interferometer and a self-designed photon counter, is able to deliver high resolution and frequency precise Raman spectra from the gasoline-ethanol blends comparable to the obtained by using commercial devices. This FT-Raman set-up does not need additional complex hardware or software control and relies on re-sampling and interpolation algorithms. The qualitative spectral information obtained has been used to calculate the proportion of gasoline and ethanol present in the used chemical samples without using extra calibrations methods or chemical markers.
Background: Increasing awareness of the importance of evidence-based medicine is demonstrated not only by an increasing number of articles addressing it but also by a specialty-wide evidence-based medicine initiative. The authors critically analyzed the quality of reporting of randomized controlled trials published in this Journal over a 21-year period (1990 to 2010).
Methods: A hand search was conducted, including all issues of Plastic and Reconstructive Surgery from January of 1990 to December of 2010. All randomized controlled trials published during this time period were identified with the Cochrane decision tree for identification of randomized controlled trials. To assess the quality of reporting, a modification of the checklist of the Consolidated Standard of Reporting Trials Statement was used.
Results: Of 7121 original articles published from 1990 to 2010 in the Journal, 159 (2.23 percent) met the Cochrane criteria. A significant increase in the absolute number of randomized controlled trials was seen over the study period (p < 0.0001). The median quality of these trials from 1990 to 2010 was "fair," with a trend toward improved quality of reporting over time (p = 0.127).
Conclusions: A favorable trend is seen with respect to an increased number of published randomized controlled trials in Plastic and Reconstructive Surgery. Adherence to standard reporting guidelines is recommended, however, to further improve the quality of reporting. Consideration may be given to providing information regarding the quality of reporting in addition to the "level of evidence pyramid," thus facilitating critical appraisal.
Energy consumption for cooling is growing dramatically. In the last years, electricity peak consumption grew significantly, switching from winter to summer in many EU countries. This is endangering the stability of electricity grids. This article outlines a comprehensive analysis of an office building performances in terms of energy consumption and thermal comfort (in accordance with static – ISO 7730:2005 – and adaptive thermal comfort criteria – EN 15251:2007 –) related to different cooling concepts in six different European climate zones. The work is based on a series of dynamic simulations carried out in the Trnsys 17 environment for a typical office building. The simulation study was accomplished for five cooling technologies: natural ventilation (NV), mechanical night ventilation (MV), fan-coils (FC), suspended ceiling panels (SCP), and concrete core conditioning (CCC) applied in Stockholm, Hamburg, Stuttgart, Milan, Rome, and Palermo. Under this premise, the authors propose a methodology for the evaluation of the cooling concepts taking into account both, thermal comfort and energy consumption.
In this paper, an unconditionally stable algorithm for the numerical integration and finite-element implementation of a class of pressure dependent plasticity models with nonlinear isotropic and kinematic hardening is presented. Existing algorithms are improved in the sense that the number of equations to be solved iteratively is significantly reduced. This is achieved by exploitation of the structure of Armstrong-Frederik-type kinematic hardening laws. The consistent material tangent is derived analytically and compared to the numerically computed tangent in order to validate the implementation. The performance of the new algorithm is compared to an existing one that does not consider the possibility of reducing the number of unknowns to be iterated. The algorithm is used to implement a time and temperature dependent cast iron plasticity model, which is based on the pressure dependent Gurson model, in the finite-element program ABAQUS. The implementation is applied to compute stresses and strains in a large-scale finite-element model of a three cylinder engine block. This computation proofs the applicability of the algorithm in industrial practice that is of interest in applied sciences.
In this paper the fatigue life of three cast iron materials, namely EN-GJS-700, EN-GJV-450 and EN-GJL-250, is predicted for combined thermomechanical fatigue and high cycle fatigue loading. To this end, a mechanism-based model is used, which is based on microcrack growth. The model considers crack growth due to low frequency loading (thermomechanical and low cycle fatigue) and due to high cycle fatigue. To determine the model parameters for the cast iron materials, fatigue tests are performed under combined loading and crack growth is measured at room temperature using the replica technique. Superimposed high cycle fatigue leads to an accelerated crack growth as soon as a critical crack length and thus the threshold stress intensity factor is exceeded. The model takes this effect into account and predicts the fatigue lives of all cast iron materials investigated under combined loadings very well.
The lifetime and performance of solid-oxide fuel cells (SOFC) and electrolyzer cells (SOEC) can be significantly degraded by oxidation of nickel within the electrode and support structures. This paper documents a detailed computational model describing nickel oxide (NiO) formation as a growing film layer on top of the nickel phase in Ni/YSZ composite electrodes. The model assumes that the oxidation rate is controlled by transport of ions across the film (Wagner's theory). The computational model, which is implemented in a two-dimensional continuum framework, facilitates the investigation of alternative chemical reaction and transport mechanisms. Model predictions agree well with a literature experimental measurement of oxidation-layer growth. In addition to providing insight in interpreting experimental observations, the model provides a quantitative predictive capability for improving electrode design and controlling operating conditions.
We present a video-densitometric quantification method in combination with diode-array quantification for the methyl-, ethyl-, propyl-, and butylparaben in cosmetics. These parabens were separated on cyanopropyl bonded plates using water-acetonitrile-dioxane-ethanol-NH3 (25%) (8:2:1:1:0.05, v/v) as mobile phase. The quantification is based on UV-measurements at 255 nm and a bioeffectively-linked analysis using Vibrio fischeri bacteria. Within 5 min, a Tidas S 700 diode-array scanner (J&M, Aalen, Germany) scans 8 tracks and thus measures in total 5600 spectra in the wavelengths range from 190 to 1000 nm. The quantification range for all these parabens is from 20 to 400 ng per band, measured at 255 nm. In the V. fischeri assay a CCD-camera registers the white light of the light-emitting bacteria within 10 min. All parabens effectively suppress the bacterial light emission which can be used for quantifying within a linear range from 100 to 400 ng. Measurements were carried out using a 16-bit MicroChemi chemiluminescence system (biostep GmbH, Jahnsdorf, Germany), using a CCD camera with 4.19 megapixels. The range of linearity is achieved because the extended Kubelka-Munk expression was used for data transformation. The separation method is inexpensive, fast, and reliable.
The IEEE802.11p standard describes a protocol for car-to-X and mainly for car-to-car-communication. It has found its place in hardware and firmware implementations and is currently tested in various field tests. In the research project Ko-TAG, which is part of the research initiative Ko-FAS, cooperative sensor technology is developed and its benefit for traffic safety applications is evaluated. A secondary radar principle based on communication signals enables localization of objects with simultaneous data transmission. It mainly concentrates on the detection of pedestrians and other vulnerable road users (VRU), but also supports pre crash safety applications. The Ko-TAG proposal enriches the current IEEE802.11p real-time characteristics needed for precise time-of-flight real-time localization. This contribution describes the development of a subsystem, which extends the functionality of IEEE802.11p and fits into the regulatory schemes. It discusses the approach for definition and verification of the protocol design, while maintaining the close coexistence with existing IEEE802.11p subsystems. System simulations were performed and hardware was implemented. The next step will be field measurements to verify the simulation results.
The communication between objects, i.e. between cars (car-2-car, C2C), between cars and infrastructure (car-2-infrastructure, C2I) and between cars and vulnerable road users (car-2-VRU, C2VRU) is a major stepping stone towards traffic applications to enable efficient and safe traffic flow. However, these applications pose very high requirements to the communication protocols, which go beyond the capabilities of an available standardized solution.
This contribution shows how iterative design processes can help to fulfill these requirements, while re-using a maximum of elements from one level to the next and thus avoiding unrealistic overhead. In especially, the added value of simulation and emulation in this iterative process is elaborated.
The formation of secondary phases in the porous electrodes is a severe mechanism affecting the lifetime of solid oxide fuel cells (SOFC). It can occur via various chemical mechanisms and it has a significant influence on cell performance due to pore clogging and deactivation of active surfaces and triple-phase boundary (TPB). We present a modeling and simulation study of nickel oxide formation (reoxidation) and carbon formation (coking) within the SOFC anode. We use a 2D continuum model based on a multi-phase framework [Neidhardt et al., J. Electrochem. Soc., 159, 9 (2012)] that allows the introduction of arbitrary solid phases (here: Ni, YSZ, NiO, Carbon) plus gas phase. Reactions between the bulk phases are modeled via interface-adsorbed species and are described by an elementary kinetic approach. Published experimental data are used for parameterization and validation. Simulations allow the prediction of cell performance under critical operation conditions, like (i) a non-fuel operation test, where NiO formation is taking place (Figure 1a), or (ii) an open circuit voltage (OCV) stability test under hydrocarbon atmosphere, where solid carbon is formed (Figure 1b). Results are applied for enhanced interpretation of experimental data and for prediction of safe operation conditions.
A series of isostructural 3D coordination polymers (3)∞[M(tdc)(bpy)] (M(2+) = Zn(2+), Cd(2+), Co(2+), Fe(2+); tdc(2-) = 2,5-thiophenedicarboxylate; bpy = 4,4'-bipyridine) was synthesized and characterized by X-ray diffraction, thermal analysis, and gas adsorption measurements. The materials show high thermal stability up to approximately 400 °C and a solvent induced phase transition. Single crystal X-ray structure determination was successfully performed for all compounds after the phase transition. In the zinc-based coordination polymer, various amounts of a second type of metal ions such as Co(2+) or Fe(2+) could be incorporated. Furthermore, the catalytic behavior of the homo- and heteronuclear 3D coordination polymers in an oxidation model reaction was investigated.
Automatic Meter Reading (AMR) is a major enabler for the upcoming smart grid. Potentially, it will be one of the first really large-scale M2M-communication solutions for sensor applications.
To date, the definition of the standardized communication stacks for Local Metrological Network (LMN) in AMR is still ongoing. This holds true both for ZigBee Smart Energy Profile and for Wireless M-Bus according to EN 13757. During this process, there is the necessity for flexible, albeit optimized solutions, which support the different existing and upcoming versions of the communication protocols. In the case of Wireless M-Bus, the major contender for European and possibly Asian installations, this is valid not only for the different operation modes (C-, N-, P-, Q-, R-, S-, and T-modes), which work in different frequencies (i.e. 868 MHz, 433 MHz, and 169 MHz) but also for the application layer, where additional bodies, like EN137575, Open Metering System (OMS) Group, or national bodies follow their approaches.
This contribution describes requirements, design techniques and experiences from the development of highly efficient Wireless M-Bus protocol stacks with support of good flexibility and portability between microcontroller platforms and RF-transceivers. The presented approach is not limited to the use of modern software engineering design processes, as such, but also includes essential additional features like testing or simulation, as well as tools for commissioning and monitoring.
Ranging errors are inevitable in all local positioning systems, including those based on Time-of-Flight (ToF) technique. Results of experiments show that the major cause for these errors is a signal degradation from multipath propagation. This effect is especially critical in case of Non-Light-of-Sight (NLOS) conditions. This paper describes causes that affects ranging errors for nanoLOC™-TOF-technology and presents estimations for the probability density functions of such errors under different NLOS conditions. The provided estimations allow the improvement of the accuracy of the localization through the subsequent mitigation of the ranging errors from the measurements. Additionally, it is proposed to increase the number of cases of NLOS-conditions for the improvement of the accuracy.