Refine
Year of publication
Document Type
- Conference Proceeding (286)
- Article (reviewed) (285)
- Article (unreviewed) (97)
- Part of a Book (77)
- Contribution to a Periodical (74)
- Report (44)
- Patent (38)
- Book (34)
- Doctoral Thesis (5)
- Working Paper (2)
Conference Type
- Konferenzartikel (205)
- Konferenz-Abstract (47)
- Konferenz-Poster (16)
- Sonstiges (14)
- Konferenzband (7)
Language
- English (562)
- German (382)
- Other language (1)
Is part of the Bibliography
- yes (945) (remove)
Keywords
- Dünnschichtchromatographie (28)
- Energieversorgung (14)
- Plastizität (13)
- Adsorption (11)
- Finite-Elemente-Methode (11)
- TRIZ (11)
- Materialermüdung (10)
- injury (10)
- Ermüdung (9)
- Geothermie (9)
Institute
- Fakultät Maschinenbau und Verfahrenstechnik (M+V) (945) (remove)
Open Access
- Open Access (400)
- Closed Access (269)
- Closed (138)
- Bronze (88)
- Gold (34)
- Hybrid (32)
- Diamond (25)
- Grün (5)
Uptakes of 9.2 mmol g−1 (40.5 wt %) for CO2 at 273 K/0.1 MPa and 15.23 mmol g−1 (3.07 wt %) for H2 at 77 K/0.1 MPa are among the highest reported for metal–organic frameworks (MOFs) and are found for a novel, highly microporous copper‐based MOF (see picture; Cu turquoise, O red, N blue). Thermal analyses show a stability of the flexible framework up to 250 °C.
Metal–organic frameworks (MOFs) as highly porous materials have gained increasing interest because of their distinct adsorption properties.1–3 They exhibit a high potential for applications in gas separation and storage,4 as sensors5 as well as in heterogeneous catalysis.6 In the last few years, the H2 storage capacity of MOFs has been considerably increased. Mesoporous MOFs show high adsorption capacities for CH4, CO2, and H2 at high pressures.2, 3, 7–10 To increase the uptake of H2 and CO2 by physisorption at ambient pressure, adsorbents with small micropores as well as high specific surface areas and micropore volumes are required.11, 12 Such microporous materials seem to be more appropriate for gas‐mixture separation by physisorption than mesoporous materials. For gas separation in MOFs the interactions between the fluid adsorptive and “open metal sites” (coordinatively unsaturated binding sites) or the ligands are regarded as important.13 Industrial processes, such as natural‐gas purification or biogas upgrading, can be improved with those materials during a vapor‐pressure swing adsorption cycle (VPSA cycle) or a temperature swing adsorption cycle (TSA cycle).14 The microporous MOF series CPO‐27‐M (M=Mg, Co, Ni, Zn), for example, shows very high CO2 uptakes at low pressures (<0.1 MPa).15, 16 Concerning H2 adsorption, the microporous MOF PCN‐12 offers with 3.05 wt % the highest uptake at ambient pressure and 77 K reported to date.17
Herein, we present a novel microporous copper‐based MOF equation image[Cu(Me‐4py‐trz‐ia)] (1; Me‐4py‐trz‐ia2−=5‐(3‐methyl‐5‐(pyridin‐4‐yl)‐4H‐1,2,4‐triazol‐4‐yl)isophthalate) with extraordinarily high CO2 and H2 uptakes at ambient pressure, the H2 uptake being similar to that in PCN‐12. The ligand Me‐4py‐trz‐ia2−, which can be obtained from cheap starting materials by a three‐step synthesis in good yield, combines carboxylate, triazole, and pyridine functions and is adopted from a recently presented series of linkers,18 for which up to now only a few coordination polymers are known.
The present study describes medium-chain-length polyhydroxyalkanoates (mcl-PHAs) production by the Pseudomonas Gl01 strain isolated from mixed microbial communities utilized for PHAs synthesis. A two-step fedbatch fermentation was conducted with glucose and waste rapeseed oil as the main carbon source for obtaining cell growth and mcl-PHAs accumulation, respectively. The results show that the Pseudomonas Gl01 strain is capable of growing and accumulating mcl-PHAs using a waste oily carbon source. The biomass value reached 3.0 g/l of CDW with 20% of PHAs content within 48 h of cultivation. The polymer was purified from lyophilized cells and analyzed by gas chromatography (GC). The results revealed that the monomeric composition of the obtained polyesters depended on the available substrate. When glucose was used in the growth phase, 3-hydroxyundecanoate and 3- hydroxydodecanoate were found in the polymer composition, whereas in the PHAs-accumulating stage, the Pseudomonas Gl01 strain synthesized mcl-PHAs consisting mainly of 3- hydroxyoctanoate and 3-hydroxydecanoate. The transcriptional analysis using reverse-transcription real-time PCR reaction revealed that the phaC1 gene could be transcribed simultaneously to the phaZ gene.
An analytical and numerical study of the wobbling dynamics of friction disks is presented. Of particular interest is the excitation mechanism taking into account two contrarian effects both originating in dry friction: the circulatory terms describing the energy input due to the sliding contacts and the friction induced damping which stabilizes the system. Balance of these terms determines the instability domain in the parameter space. It is shown that there is a slip threshold so that, if the slip is under this limit, the system remains stable. If the slip is larger than this limit, then the criterion of stability is determined by the relation between the friction coefficient and the internal damping. The limit cycle appearing in the unstable domain is also investigated. It is shown that the limit cycle can be described as a kind of a regular reverse precession of the wobbling disc. Its amplitude is limited by the geometric nonlinearity and partial contact loss. Analytic results are compared with numeric simulations.
This work provides a series of methane adsorption isotherms and breakthrough curves on one 5A zeolite and one activated carbon. Breakthrough curves of CH4 were obtained from dynamic column measurements at different temperature and pressure conditions for concentrations of 4.4 – 17.3 mol.‐% in H2/CH4 mixtures. A simple model was developed to simulate the curves using measured and calculated data inputs. The results show that the model predictions agree very well with the experiments.
Regarding the importance of adsorptive removal of carbon monoxide from hydrogen-rich mixtures for novel applications (e.g. fuel cells), this work provides a series of experimental data on adsorption isotherms and breakthrough curves of carbon monoxide. Three recently developed 5A zeolites and one commercial activated carbon were used as adsorbents. Isotherms were measured gravimetrically at temperatures of 278–313 K and pressures up to 0.85 MPa. Breakthrough curves of CO were obtained from dynamic column measurements at temperatures of 298–301 K, pressures ranging from 0.1 MPa to ca. 6 MPa and concentrations of CO in H2/CO mixtures of 5–17.5 mol%. A simple mathematical model was developed to simulate breakthrough curves on adsorbent beds using measured and calculated data as inputs. The number of parameters and the use of correlations to evaluate them were restricted in order to focus the importance of measured values. For the given assumptions and simplifications, the results show that the model predictions agree satisfactorily with the experimental data at the different operating conditions applied.
Cost effectiveness of preventive screening programmes for type 2 diabetes mellitus in Germany
(2010)
As in several other industrialized countries, Germany’s statutory health insurance (SHI) is facing rising healthcare costs as well as the challenges caused by a double-aging society. The early detection and prevention of chronic diseases is considered a possible way to reduce the impact of these developments. However, controversy surrounds the costs and effects in terms of medical and financial outcomes of such programmes.
The engineering company Evomotiv GmbH and the University of Applied Sciences Offenburg have developed a drive concept for light city scooters since 2008. The electrical drive train's goal is the series production of the highly-integrated, non-transmission and non-ferrous wheel-hub motor. The German Federal Ministry of Economy and Technology (BMWi) supports this project. The concept of this wheel-hub motor was awarded with the Bosch-Innovation prize in 2006. In 2011 Evomotiv will test the first prototypes with its cooperation partners on the track.
Thin-layer chromatography is a rapid and reliable working method for quantification of mycotoxins which is suitable for checking EC legislation aflatoxin limits for dried figs without an RP-18 pre-column cleaning step. We describe normal-phase chromatography on silica gel plates with 2.4:0.05:0.1:0.05 ( v/v ) methyl t -butyl ether-water-methanol-cyclohexane as mobile phase and reversed-phase chromatography on RP-18 plates with methanol-4% aqueous ZnSO 4 solution-ethyl methyl ketone 15:15:3 ( v/v ) as mobile phase. Sample pretreatment was by modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) extraction with tetrahydrofuran or acetone. NaCl was used as QuEChERS salt. Response was a linear function of amount chromatographed in the ranges 3 to 100 pg per zone for aflatoxins B 2 and G 2 , 10 to 350 pg per zone for the aflatoxins B 1 and G 1 , and 0.25 to 2.5 ng per zone for ochratoxin A. Quantification limits for the aflatoxins were between 13 and 35 pg per zone (equivalent to 1.5 and 2.4 ppb, taking the pre-treatment procedure into account). Ochratoxin A was detectable with a limit of quantification of 970 pg per zone, corresponding to 56 ppb in the sample. Normal phase and RP-18 separations work rapidly, reliably, and at low cost. They are also suitable for checking the content of the mycotoxins patulin, penicillic acid, zearalenone, and deoxynivalenol.
Hydrogen chloride and sulphur dioxide are gaseous by-products of chloridization processes that employ thionyl chloride. Absorption would be a feasible method to clean the rich gas stream. Two serial connectable absorption columns were equipped with the latest generation of packings to effect product recovery. Therefore, several tests concerning the baffle properties had to be performed. In the first experimental section, the hydraulic parameters pressure drop and hold-up were investigated. The hold up value range of the new baffles Raschig Super Ring (RSR) and Raschig Super Pak (RSP) was clearly below that of the former installed packing, Raschig Ring (RR). However, due to the low maximal flow rate, the range of stagnation and flooding could not be measured. The maximal measured pressure drop value was, for RR, only 0.3 mbar/m, which is very low compared to the measurement error. Batch experiments, where the waste gases were produced by reaction of thionyl chloride in water, showed that for the steady state determination of the separation steps it is advisable to use just one column in simplex mode with a defined gas supply by a gas cylinder. The HTU determination for RSR and a HCl/H2O system delivered a value of HTUHCl,OG = 0.14 ± 0.01 m with a variation coefficient of 24.2%.
A diode array HPTLC method for dequalinium chloride in pharmaceutical preparations is presented. For separation a Nano TLC silica gel plate (Merck) is used with the mobile phase methanol-7.8% aqueous NH(4)(+)CH(3)COO(-) (17:3, v/v) over a distance of 6 cm. Dequalinium chloride shows an R(F) value of 0.58. Pure dequalinium chloride is measured in the wavelength range from 200 to 500 nm and shows several by-products, contour plot visualized in absorption, fluorescence and using the Kubelka-Munk transformation. Scanning of a single track in absorption and fluorescence measuring 600 spectra in the range from 200 to 1100 nm takes 30s. As a sample pre-treatment of an ointment it is simply dissolved in methanol and can be quantified in absorption from 315 to 340 nm. The same separation can also be quantified using fluorescence spectrometry in the range from 355 to 370 nm. A new staining method for dequalinium chloride, using sodium tetraphenyl borate/HCl in water allows a fluorescence quantification in the range from 445 to 485 nm. The linearity range of absorption and fluorescence measurements is from 10 to 2000 ng. Sugar-containing preparations like liquids or lozenges with a reduced sample pre-treatment can be reliably quantified only in fluorescence. The total for the quantification of an ointment sample (measuring four standards and five samples), including all sample pre-treatment steps takes less than 45 min!
We report improved separation of the highly toxic contact herbicides paraquat, diquat, difenzoquat, mepiquat, and chloromequat by HPTLC. Quantification was based on a new derivatization reaction using sodium tetraphenylborate. Measurements were in the wavelength range from 440 to 480 nm or from 440 to 590 nm. An LED emitting very intense light at 365 nm was used for excitation. The quantification limits of paraquat and diquat in water, using improved solid-phase extraction, was in the low ng L −1 range. The linear range covered more than two orders of magnitude. Recovery was investigated for all the compounds, and was insufficient, ranging from 11 to 92%, but the method is inexpensive, rapid, and works reliably.
Flows in nature and technology are often associated with specific structures and pattern. This paper deals with the development and behaviour of such flow pattern. Flow structures are important for the mass, momentum and energy transport. The behaviour of different flow pattern is used by engineers to obtain an efficient mass and energy consumption. Mechanical power is transmitted via the momentum of rotating machine parts. Therefore the physical and mathematical knowledge of these basic concepts is important. Theoretical and experimental investigations of principle experiments are described in the following. We start with the classical problem of the flow between two concentric cylinders where the inner cylinder rotates. Periodic instabilities occur which are called Taylor vortices. The analogy between the cylindrical gap flow, the heat transfer in a horizontal fluid layer exposed to the gravity field and the boundary layer flow along concave boundaries concerning their stability behaviour is addressed. The vortex breakdown phenomenon in a cylinder with rotating cover is also described. A generalization to spherical sectors leads then to investigations with different boundary conditions. The spherical gap flow exhibits interesting phenomena concerning the nonlinear character of the Navier-Stokes equations. Multiple solutions in the nonlinear regime give rise to different routes during the laminar-turbulent transition. The interaction of two rotating spheres results in flow structures with separation and stagnation lines. Experimental results are confirmed by numerical simulations.
The efficiency of a chromatographic analytical method is determined by the selectivity of the chromatographic separation and the specificity of the detection method. In high-performance thin-layer chromatography (HPTLC) the separated components can be detected and quantified directly on the plate by physical and chemical methods. By coupling high-performance thin-layer chromatography with biological or biochemical inhibition tests it is possible to detect toxic substances in situ.
We present an improved quantification method for urethane found in spirits. The quantification is based on a derivatization reaction using cinnamaldehyde in combination with phosphoric acid. Measurements were carried out in the wavelength range from 445 to 460 nm using a diode-TLC device. An LED was used for illumination purposes. It emits very dense light at 365 nm. The quantification range of urethane is in the lower ng range. By applying 20 µL of sprits, the urethane quantification range is from 320 µg/L to 8.1 mg urethane per litre of spirit. The range of linearity covers nearly two magnitudes. The method is cheap, fast and reliable, and is able to monitor all European legislation limits without time-consuming sample pre-treatments.
HPTLC on amino plates, with simple heating of the plates for derivatization, has been used for quantification of glucosamine in nutritional supplements. On heating the plate glucosamine reacts to form a compound which strongly absorbs light between 305 and 330 nm, with weak fluorescence. The reaction product can be detected sensitively either by absorption of light or by fluorescence detection. The detection limit in absorption mode is approximately 25 ng per spot. In fluorescence mode a detection limit of 15 ng is achievable. A calibration plot for absorption detection is linear in the range 25 to 4000 ng glucosamine. The derivative formed from glucosamine by heating is stable for months, and the relative standard deviation is 1.64% for 600 ng glucosamine. The amounts of glucosamine found in nutritional supplements were in agreement with the label declarations.
Die dynamische Steifigkeit von Werkzeugmaschinenbetten kann durch Daempfung gesteigert werden. Die spezifische Daempfung ( Werkstoffdaempfung = innere Daempfung) wird anhand der Hysteresisschleife definiert. Der spezifische Daempfungswert von C 45 ist nur 0,20 des Wertes von GGL 20. Aeussere Daempfung kann durch Reibstellen erzielt werden; z.B. Fuellen der Hohlraeume eines Bettes mit Kernsand; Reibstellen zwischen den verschweissten Rippen mit Vorder- und Rueckwand. Es wird eine Methode beschrieben, nach der das Schwingungsverhalten ueberprueft werden kann. Das Ergebnis dieser Messung wird in Diagrammform fuer eine ausgefuehrte Maschine dargestellt. Schwingungsuntersuchungen sind auch an einem Modell aus Schaumstoffgummi durchfuehrbar. (Poesl, 10.12.72)
The identification and quantification of compounds in the gas phase becomes of increasing interest in the context of environmental protection, as well as in the analytical field. In this respect, the high extinction coefficients of vapours and gases in the ultraviolet wavelength region allow a very sensitive measurement system. In addition, the increased performance of the components necessary for setting up a measurement system, such as fibres, light sources and detectors has been improved. In particular the light sources and detectors offer improved stability, and the deep UV performance and solarisation resistance of fused silica fibres allow have been significantly optimized in the past years. Therefore a compact and reliable detection system with high measuring accuracy is developed. Within this paper possible applications of the system under development and recent results will be discussed.
Soot particles emitted from a light duty (LD) Volkswagen diesel engine running at different operating points (speed and torque levels) are analyzed for mean size determination using a laser‐based three Wavelength Extinction Method (3‐WEM). For this reason, collected soot samples are suspended using an appropriate sample preparation technique with optimized conditions of sonication as it revealed its effect on the soot mean particle size measured by 3‐WEM.
An online Scanning Mobility Particle Analyzer (SMPS) is also used to measure soot emission at identical engine operating points. Size values obtained from SMPS are lower than those of suspended soot samples obtained from 3‐WEM. The size discrepancies are mainly related to the required sample preparation procedure employed for 3‐WEM measurements. The engine operating points affect, differently, the size measurements obtained from SMPS and 3‐WEM.
Sedimentation Field‐Flow Fractionation (SdFFF) is used for density determination of soot samples based on size measurements of fractions collected at peak maxima of fractograms using the off‐line hyphenation with 3‐WEM. It is assumed that a size dependent separation of soot particles occurred with a uniform particle density over the whole size distribution. An average density value is used for the conversion of soot fractograms to size distributions. Discrepancies are also found with size distribution profiles obtained from SMPS for the same engine operating points, due to the sample preparation procedure employed for SdFFF measurements.
The identification and quantification of compounds in the gas phase becomes of increasing interest in the context of environmental protection, as well as in the analytical field. In this respect, the high extinction coefficients of vapours and gases in the ultraviolet wavelength region allow a very sensitive measurement system. In addition, the increased performance of the components necessary for setting up a measurement system, such as fibres, light sources and detectors has been improved. In particular the light sources and detectors offer improved stability, and the deep UV performance and solarisation resistance of fused silica fibres allow have been significantly optimized in the past years. Therefore a compact and reliable detection system with high measuring accuracy is developed. Within this paper possible applications of the system under development and recent results will be discussed.
The structure of the separation bubble that appears in the secondary meridional flow between two coaxially rotating spheres at low and finite Reynolds number (Re) is considered. The low Re analytical study was motivated by recognizing some errors in the analytical work on this problem by Arunachalam and Majhi (1987, Q. Jl Mech. Appl. Math., 40, 47) whilst the finite Re experimental study was motivated by the desire to observe the separation bubble in the laboratory. Though the finite Re experiments were performed in a confined apparatus, they exhibit the qualitative features of the low Re theoretical predictions for the axisymmetric separation bubble that encloses two toroidal vortices symmetrically disposed above and below the mid‐plane of sphere separation, but strong effects of confinement are apparent. The flows observed include (i) a wall‐attached bubble symmetric about the mid‐plane at low Re, (ii) symmetric free‐standing bubbles at moderate Re, and (iii) an asymmetric bubble with flow separating from one sphere and attaching to the support shaft between the spheres at sufficiently high Re.
The free convection in a vertical gap is generalized to realize new analytical solutions of the Boussinesq-equations. The steady and time-dependent solutions for the temperature and velocity distribution are discussed in detail depending on the mass flux in vertical direction. The range of existence for flows with and without back flow is obtained. The transient behaviour of the solutions during the time-dependent development displays interesting physical behaviour.
The use of a TLC scanner can be regarded as a key step in high performance thin layer chromatography (HPTLC). Densitometric measurements transform the substance distribution on a TLC plate into digital computer data. Systems that allow quantitative measurements have been available for many years for either fluorescence or ultraviolet absorption measurements, while lately the reflection analysis mode for both types is the most common application. New scanning approaches are designed to aid the analyst who has common demands for TLC-densitometry without using special data, such as scanned images. Two examples that have been developed lately in the laboratories of the authors are described in this paper. These approaches were developed on the basis of current needs for analysts who employ TLC as a tool in research, as well as in routine analysis. One approach is aimed to support analysts in economically disadvantaged areas, where cost intensive apparatus is unsuitable but trace analysis by simple means is required. The other system, allows the spectral determination of chromatographic spots on TLC plates covering the ultraviolet and visible range, thus, revealing highly desired information for the analyst.
HPTLC (High Performance Thin Layer Chromatography) is a well known and versatile separation method which shows a lot of advantages and options in comparison to other separation techniques. The method is fast and inexpensive and does not need time-consuming pretreatments. Using fiber-optic elements for controlled light-guiding, the TLC-method was significantly improved: the new HPTLC-system is able to measure simultaneously at different wavelengths without destroying the plate surface or the analytes on the surface. For registration of the sample distribution on a HPTLC-plate we developed a new and sturdy diode-array HPTLC- scanner which allows registration of spectra on the TLC- plates in the range of 198 nm to 610 nm with a spectral resolution better than 1.2 nm. The spatial resolution on plate is better than 160 micrometers . In the spectral mode, the new HPTLC-scanner delivers much more information than the commonly used TLC-scanner. The measurement of 450 spectra of one separation track does not need more than three minutes. However, in the fixed wavelength mode the contour plot can be measured within 15 seconds. In this case, the signal will be summarized and averaged over a spectral range having FWHM from 10 nm to 25 nm depending on the substance under test. The new diode-array HPTLC-scanner makes various chemometric applications possible. The new method can be used easily in clinical diagnostic systems easily, e.g. for blood and uring investigations. In addition, new applications are possible. For example, the rich structured PAHs were studied. Although the separation is incomplete the 16 compounds can be quantified using suitable wavelengths.
The aim of this study was to develop a biomechanically validated finite element model to predict the biomechanical behaviour of the human lumbar spine in compression.
For validation of the finite element model, an in vitro study was performed: Twelve human lumbar cadaveric spinal segments (six segments L2/3 and six segments L4/5) were loaded in axial compression using 600 N in the intact state and following surgical treatment using two different internal stabilisation devices. Range of motion was measured and used to calculate stiffness.
A finite element model of a human spinal segment L3/4 was loaded with the same force in intact and surgically altered state, corresponding to the situation of biomechanical in vitro study.
The results of the cadaver biomechanical and finite element analysis were compared. As they were close together, the finite element model was used to predict: (1) load-sharing within human lumbar spine in compression, (2) load-sharing within osteoporotic human lumbar spine in compression and (3) the stabilising potential of the different spinal implants with respect to bone mineral density.
A finite element model as described here may be used to predict the biomechanical behaviour of the spine. Moreover, the influence of different spinal stabilisation systems may be predicted.
Ozon-Querempfindlichkeit bei der Immissionsmessung von schwebstaubakkumuliertem Benzo[a]pyren
(2002)
Für die Beschreibung der Belastung der Luft mit polycyclischen aromatischen Kohlenwasserstoffen (PAK) wird vorwiegend die Konzentration eines Vertreters, das auf Schwebstaub akkumulierte Benzo[a]pyren (BaP), analysiert. Hierbei stellt Benzo[a]pyren die Leit komponen te für die Stoffklasse der PAK dar. Auf europäischer Ebene ist vorgesehen, für diesen Luftinhaltsstoff einen Grenzwert als Jahresmittelwert festzulegen. Deshalb wird bei bei der Normungsbehörde CEN zurzeit eine Europäische Norm für diesen Stoff erarbeitet. Aus der Literatur ist bekannt, dass für Benzo[a]pyren eine Querempfindlichkeit gegen Ozon und NO2 besteht. Im Zuge der Neuentwicklung eines Probenahmekopfs (PNK) für PAK-Immissionsmessungen, der durch den Einsatz eines Ozon- Scrubbers eine ozonfreie Immissionsmessung der Benzo[a]pyren-Konzentration ermög licht, wurde in dieser Arbeit die prinzipielle Einsetzbarkeit dieses Probe nahmekopfs geprüft. Zu diesem Zweck wurden Voruntersuchungen und Feldversuche durchgeführt, mit dem Ziel, Kenntnisse über die Ozon-Querempfindlichkeit zu erhalten. Um die Ozon-Querempfindlichkeit bei der Benzo[a]pyren-Bestimmung zu studieren, wurde Ozon in den Ansaugbereich der Probenahme dosiert. Als Ergebnis der Untersuchungen kann festgehalten werden, dass für die Benzo[a]pyren-Immissionsmessung eine deutliche Ozon-Querempfindlichkeit besteht, die unter Einsatz des neuen Ozon- Scrubbers vermieden werden kann.
A systematic toxicological analysis procedure using high-performance thin layer chromatography in combination with fibre optical scanning densitometry for identification of drugs in biological samples is presented. Two examples illustrate the practicability of the technique. First, the identification of a multiple intake of analgesics: codeine, propyphenazone, tramadol, flupirtine and lidocaine, and second, the detection of the sedative diphenhydramine. In both cases, authentic urine specimens were used. The identifications were carried out by an automatic measurement and computer-based comparison of in situ UV spectra with data from a compiled library of reference spectra using the cross-correlation function. The technique allowed a parallel recording of chromatograms and in situ UV spectra in the range of 197–612 nm. Unlike the conventional densitometry, a dependency of UV spectra by concentration of substance in a range of 250–1000 ng/spot was not observed.
In-situ densitometry for qualitative or quantitative purposes is a key step in thin-layer chromatography (TLC). It is a simple means of quantification by measurement of the optical density of the separated spots directly on the plate. A new scanner has been developed which is capable of measuring TLC or HPTLC (high-performance thin-layer chromatography) plates simultaneously at different wavelengths without damaging the plate surface. Fiber optics and special fiber interfaces are used in combination with a diode-array detector. With this new scanner sophisticated plate evaluation is now possible, which enables use of chemometric methods in HPTLC. Different regression models have been introduced which enable appropriate evaluation of all analytical questions. Fluorescent measurements are possible without filters or special lamps and signal-to-noise ratios can be improved by wavelength bundling. Because of the richly structured spectra obtained from PAH, diode-array HPTLC enables quantification of all 16 EPA PAH on one track. Although the separation is incomplete all 16 compounds can be quantified by use of suitable wavelengths. All these aspects are enable substantial improvement of in-situ quantitative densitometric analysis.
HPTLC (High Performance Thin Layer Chromatography) is a well known and versatile separation method which shows many advantages when compared to other separation techniques. The method is fast and inexpensive and does not need time-consuming pretreatments. For visualisation of the sample distribution on a HPTLC-plate we developed a new and sturdy HPTLC-scanner. The scanner allows simultaneous registrations of spectra in a range from 198 nm to 612 nm with a spectral resolution of better than 0.8 nm. The on-plate spatial resolution is better than 160 μm. The measurement of 450 spectra in one separation track does not need more than two minutes. The new diode-array scanner offers a fast survey over a TLC-separation and makes various chemometric applications possible. For compound identification a cross-correlation function is described to compare UV sample spectra with appropriate library data. The cross-correlation function herein described can also be used for purity testing. Unresolved peaks can be virtually separated by use of a least squares fit algorithm. In summary, the diode arry system delivers much more information than the commonly used TLC-scanner.
A prototype multiwavelength sensor able to characterise soot emissions in Diesel exhaust in terms of size and concentration has been tested against other methods for diesel particle measurements like electrical mobility sizing (SMPS) and raw exhaust gravimetric sampling (RES). Measurements carried out with the prototype sensor were correlated with the SMPS by assuming spherical and/or fractal aggregate morphology of the particles. Correlation of RES gravimetric data against the sensor and the SMPS led to the calculation of the solid density for soot particles to be 2.3 gr/cm3.
Rotating flow systems are often used to study stability phenomena and structure developments. The closed spherical gap problem is generalized into an open flow system by superimposing a mass flux in meridional direction. The basic solutions at low Reynolds numbers are described by analytical methods. The nonlinear supercritical solutions are simulated numerically and realized in experiments. Novel steady and time-dependent modes of flows are obtained. The extensive results concern the stability behaviour, non-uniqueness of supercritical solutions, symmetry behaviour and transitions between steady and time-dependent solutions. The experimental investigations concern the visualization of the various instabilities and the quatitative description of the flow structures including the laminar-turbulent transition. A comparison between theoretical and experimental results shows good agreement within the limit of rotational symmetric solutions from the theory.
An algorithm is presented that has successfully been utilized in practice for several years. It improves data analysis in chromatography. The program runs in an extremely reliable way and evaluates chromatographic raw data with an acceptable error. The algorithm requires a minimum of preliminaries and integrates even unsmoothed noisy data correctly.
In this paper a high-performance thin-layer chromatography (HPTLC) scanner is presented in which a special fibre arrangement is used as HPTLC plate scanning interface. Measurements are taken with a set of 50 fibres at a distance of 400 to 500 μm above the HPTLC plate. Spatial resolutions on the HPTLC plate of better than 160 μm are possible. It takes less than 2 min to scan 450 spectra simultaneously in a range of 198 to 610 nm. The basic improvement of the item is the use of highly transparent glass fibres which provide excellent transmission at 200 nm and the use of a special fibre arrangement for plate illumination and detection.
Shapes and structures of vortex breakdown phenomena in rotating fluids are visualized. We investigate the flow in a cylindrical container and in a cone between two spherical surfaces. The primary swirling flow is induced by the rotating upper disk in the cylindrical case and by the lower boundary in the spherical case. The upper surface can be fixed with a no slip condition or can be a stress-free surface. Depending on these boundary conditions and on the Reynolds number novel structures of recirculation zones are realized. Experiments are done to visualize the topological structure of the flow and to determine their existence range as function of the geometry and rotation rate. A comparison between the experimental and theoretical approach shows a good agreement in respect to the topological structures of the flows.
Numerische Physik
(2019)
Dieses Lehrbuch stellt die Numerische Physik anhand einer Vielzahl von Beispielen aus den Bereichen Mechanik, Elektrodynamik, Optik, Statistischer Physik und Quantenmechanik dar. Der Leser lernt hier nicht nur die wichtigsten numerischen Techniken in der Programmiersprache C++ kennen, sondern erhält auch neue Einblicke in die Physik, die konventionelle Zugänge nicht bieten. Das Werk schließt damit eine Lücke zwischen den Standardlehrbüchern der Theoretischen Physik und denen der reinen Programmierung.
Zu jedem der physikalischen Themen gibt es eine kurze Wiederholung des theoretischen Hintergrunds und anschließend werden ausgewählte Beispiele im Detail ausgearbeitet. Übungen am Ende des Kapitels bieten weitere Gelegenheit die Anwendungen des Gelernten zu vertiefen.
Das Buch richtet sich vornehmlich an Physikstudierende höherer Semester, die bereits über eine Basis in Theoretischer Physik verfügen und auch Grundkenntnisse in der Programmierung in C++ mitbringen.
Auf der Produktseite zum Buch auf springer.com finden sich alle Quelltexte zu den Programmen im Buchtext zum Download. Im Anhang erhalten Sie eine Zusammenstellung und Erläuterung frei verfügbarer Software, die sowohl dem Windows-Anwender als auch dem Linux-Freund alle Werkzeuge an die Hand gibt, die er zur Bearbeitung anspruchsvoller physikalischer Fragestellungen benötigt - von Compilern über numerische Bibliotheken bis hin zu Visualisierungstools.
Vorrichtung (2) zur Analyse von Urin, umfassend: – eine Zuführ- und Abführeinrichtung (7), welche zur Zuführung einer bestimmten Urinmenge in eine wenigstens einen Analysebereich (8) aufweisende Analysekammer (9) eines Urinteststreifens (10) und zur Abführung einer bestimmten Urinmenge aus einer wenigstens einen Analysebereich (8) aufweisenden Analysekammer (9) eines Urinteststreifens (10) eingerichtet ist, wobei die Zuführ- und Abführeinrichtung (7) wenigstens ein bewegbar gelagertes Zuführ- und/oder Abführelement (28, 29) zum Zuführen einer bestimmten Urinmenge in einen Zuführbereich (33) der Analysekammer (9) des Urinteststreifens (10) und/oder zum Abführen einer bestimmten Urinmenge aus einem Abführbereich (34) der Analysekammer (9) des Urinteststreifens (10) aufweist, und – eine Erfassungseinrichtung (11), welche zur Erfassung einer zumindest abschnittsweisen Änderung wenigstens eines optisch erfassbaren Parameters, welcher sich in Abhängigkeit der Zusammensetzung einer diesen kontaktierenden Urinmenge optisch erfassbar verändert, des oder eines entsprechenden Analysebereichs (8) des oder eines entsprechenden Urinteststreifens (10) sowie zur Erzeugung einer Erfassungsinformation, welche wenigstens einen optisch erfassten Parameter des oder eines entsprechenden Analysebereichs (8) oder eine Änderung eines solchen beschreibt, eingerichtet ist.
Vorrichtung (2) zur Analyse von Urin, umfassend: – eine Zuführ- und Abführeinrichtung (7), welche zur Zuführung einer bestimmten Urinmenge in eine wenigstens einen Analysebereich (8) aufweisende Analysekammer (9) eines Urinteststreifens (10) und zur Abführung einer bestimmten Urinmenge aus einer wenigstens einen Analysebereich (8) aufweisenden Analysekammer (9) eines Urinteststreifens (10) eingerichtet ist, wobei die Zuführ- und Abführeinrichtung (7) wenigstens ein bewegbar gelagertes Zuführ- und/oder Abführelement (28, 29) zum Zuführen einer bestimmten Urinmenge in einen Zuführbereich (33) der Analysekammer (9) des Urinteststreifens (10) und/oder zum Abführen einer bestimmten Urinmenge aus einem Abführbereich (34) der Analysekammer (9) des Urinteststreifens (10) aufweist, und – eine Erfassungseinrichtung (11), welche zur Erfassung einer zumindest abschnittsweisen Änderung wenigstens eines optisch erfassbaren Parameters, welcher sich in Abhängigkeit der Zusammensetzung einer diesen kontaktierenden Urinmenge optisch erfassbar verändert, des oder eines entsprechenden Analysebereichs (8) des oder eines entsprechenden Urinteststreifens (10) sowie zur Erzeugung einer Erfassungsinformation, welche wenigstens einen optisch erfassten Parameter des oder eines entsprechenden Analysebereichs (8) oder eine Änderung eines solchen beschreibt, eingerichtet ist.
Modelling detailed chemistry in lithium-ion batteries: Insight into performance, ageing and safety
(2018)
Die vorliegende Erfindung betrifft ein Verfahren zum Pulverlackieren eines Kunststoff- oder Glasgegenstandes, umfassend die Schritte des Ausbildens einer polaren Beschichtung auf dem Kunststoff- oder Glasgegenstand, umfassend den Teilschritt des Aufbringens einer Beschichtungszusammensetzung auf den Kunststoff- oder Glasgegenstand, wobei die Beschichtungszusammensetzung ein Organosiloxan, das mindestens zwei Si-O-Bindungen aufweist, Wasser, ein organisches Lösemittel und ein pH-regulierendes Mittel, ausgewählt aus einer Brönsted-Säure, in einer katalytischen Menge enthält, mit der Maßgabe, dass die Beschichtungszusammensetzung keinen elektrisch leitfähigen Zusatz, ausgewählt aus ionischen Verbindungen, Metallen, Metall(misch)oxiden, intermetallischen Verbindungen und leitfähigem Kohlenstoff, enthält, sowie die Schritte des Aufbringens eines Pulverlacks auf den derartig beschichteten Kunststoff- oder Glasgegenstand und des Erwärmens des Pulverlacks.
Poröse Massen oder Formkörper aus anorganischen polymeren und deren Herstellung (WO002014127762A1)
(2014)
Es wird ein Verfahren zur Herstellung einer porösen Masse oder eines porösen Formkörpers aus anorganischem Polymer beschrieben, bei dem Wasserglas mit einem Carbonat in bestimmten Mengen gehärtet wird und dabei verschiedene weitere Stoffe zugesetzt werden können. Außerdem werden poröse Massen und Formkörper, die mit diesem Verfahren erhältlich sind, beschrieben und deren Verwendung.
Colored glass products with various printing technologies are becoming more important in industry. The aim is to achieve individual solution in a very short delivery time. Conventional thermal treatment of burning glasses in oven for tempered color printing has predominant issues with high time consumption, energy consumption and manufacturing cost. It requires alternative process development.
This paper proposes laser process to overcome issues in conventional treatment with the latest results of tempering colored glass. Samples have been analyzed with the scanning electron microscope (SEM). Two different laser systems have been applied and the glass has been printed with black paste.
In recent years, the application of TRIZ methodology in the process engineering has been found promising to develop comprehensive inventive solution concepts for process intensification (PI). However, the effectiveness of TRIZ for PI is not measured or estimated. The paper describes an approach to evaluate the efficiency of TRIZ application in process intensification by comparing six case studies in the field of chemical, pharmaceutical, ceramic, and mineral industries. In each case study, TRIZ workshops with the teams of researchers and engineers has been performed to analyze initial complex problem situation, to identify problems, to generate new ideas, and to create solution concepts. The analysis of the workshop outcomes estimates fulfilment of the PI-goals, impact of secondary problems, variety and efficiency of ideas and solution concepts. In addition to the observed positive effect of TRIZ application, the most effective inventive principles for process engineering have been identified.
Identification of Secondary Problems of New Technologies in Process Engineering by Patent Analysis
(2018)
The implementation of new technologies in production plants often causes negative side effects and drawbacks. In this context, the prediction of the secondary problems and risks can be used advantageously for selecting best solutions for intensification of the processes. The proposed method puts primary emphasis on systematic and fast anticipation of secondary problems using patent documents, and on extraction and prediction of possible engineering contradictions within novel technical systems. The approach comprises three ways to find secondary problems: (a) direct knowledge-based identification of secondary problems in new technologies or equipment; (b) identification of secondary problems of prototypes mentioned in patent citation trees; and (c) prediction of negative side effects using the correlation matrix for invention goals and secondary problems in a specific engineering domain.
The research work analyses the relationship of 155 Process Intensification (PI) technologies to the components of the Theory of Inventive Problem Solving (TRIZ). It outlines TRIZ inventive principles frequently used in PI, and identifies opportunities for enhancing systematic innovation in process engineering by applying complementary TRIZ and PI. The study also proposes 70 additional inventive TRIZ sub-principles for the problems frequently encountered in process engineering, resulting in the advanced set of 160 inventive operators, assigned to the 40 TRIZ inventive principles. Finally, we analyse and discuss inventive principles used in 150 patent documents published in the last decade in the field of solid handling in the ceramic and pharmaceutical industries.
Process engineering (PE) focuses on the design, operation, control and optimization of chemical, physical and biological processes and has applications in many industries. Process intensification (PI) is the key development approach in the modern process engineering. The theory of inventive problem solving (TRIZ) is today considered as the most comprehensive and systematically organized invention knowledge and creative thinking methodology. This paper analyses the opportunities of TRIZ application in PE and especially in combination with PI. In this context the paper outlines the major challenges for TRIZ application in PE, conceptualizes a possible TRIZ-based approach for process intensification and problem solving in PE, and defines the corresponding research agenda. It also presents the results of the original empirical innovation research in the field of solid handling in the ceramic industry, demonstrates a method for identification and prediction of contradictions and introduces the concept of the probability of contradiction occurrence. Additionally, it describes a technique of process mapping that is based on the function and multi-screen analysis of the processes. This technique is illustrated by a case study dealing with granulation process. The research work presented in this paper is a part of the European project “Intensified by Design® platform for the intensification of processes involving solids handling”.
The modern TRIZ is today considered as the most organized and comprehensive methodology for knowledge-driven invention and innovation. When applying TRIZ for inventive problem solving, the quality of obtained solutions strongly depends on the level of completeness of the problem analysis and the abilities of designers to identify the main technical and physical contradictions in the inventive situation. These tasks are more complex and hence more time consuming in the case of interdisciplinary systems. Considering a mechatronic product as a system resulting from the integration of different technologies, the problem definition reveals two kinds of contradictions: 1) the mono-disciplinary contradictions within a homogenous sub-system, e.g., only mechanical or only electrical; 2) the interdisciplinary contradictions resulting from the interaction of the mechatronic sub-systems (mechanics, electrics, control and software). This paper presents a TRIZ-based approach for a fast and systematic problem definition and contradiction identification, which could be useful both for engineers and students facing mechatronic problems. It also proposes some useful problem formulation tech-niques such as the System Circle Diagram, the enhancement of System Operator with the Evolution Patterns, the extension of MATChEM-IB operator with Infor-mation field and Human Interactions, as well as the Cause-Effect-Matrix.
Economic growth and ecological problems motivate industries to apply eco-friendly technologies and equipment. However, environmental impact, followed by energy and material consumption still remain the main negative implications of the technological progress in process engineering. Based on extensive patent analysis, this paper assigns more than 250 identified eco-innovation problems and requirements to 14 general eco-categories with energy consumption and losses, air pollution, and acidification as top issues. It defines primary eco-engineering contradictions, in case eco-problems appear as negative side effects of the new technologies, and secondary eco-engineering contradictions, if eco-friendly solutions have new environmental drawbacks. The study conceptualizes a correlation matrix between the eco-requirements for prediction of typical eco-contradictions on example of processes involving solids handling. Finally, it summarizes major eco-innovation approaches including Process Intensification in process engineering, and chronologically reviews 66 papers on eco-innovation adapting TRIZ methodology. Based on analysis of 100 eco-patents, 58 process intensification technologies, and literature, the study identifies 20 universal TRIZ inventive principles and sub-principles that have a higher value for environmental innovation.
Economic growth and ecological problems have pushed industries to switch to eco-friendly technologies. However, environmental impact is still often neglected since production efficiency remains the main concern. Patent analysis in the field of process engineering shows that, on the one hand, some eco-issues appear as secondary problems of the new technologies, and on the other hand, eco-friendly solutions often show lower efficiency or performance capability. The study categorizes typical environmental problems and eco-contradictions in the field of process engineering involving solids handling and identifies underlying inventive principles that have a higher value for environmental innovation. Finally, 42 eco-innovation methods adapting TRIZ are chronologically presented and discussed.
Accelerated transformation of the society and industry through digi-talization, artificial intelligence and other emerging technologies has intensified the need for university graduates that are capable of rapidly finding breakthrough solutions to complex problems, and can successfully implement innovation con-cepts. However, there are only few universities making significant efforts to com-prehensively incorporate creative and systematic tools of TRIZ (theory of in-ventive problem solving) and KBI (knowledge-based innovation) into their de-gree structure. Engineering curricula offer little room for enhancing creativity and inventiveness by means of discipline‐specific subjects. Moreover, many ed-ucators mistakenly believe that students are either inherently creative, or will in-evitably obtain adequate problem-solving skills as a result of their university study. This paper discusses challenges of intelligent integration of TRIZ and KBI into university curricula. It advocates the need for development of standard guidelines and best-practice recommendations in order to facilitate sustainable education of ambitious, talented, and inventive specialists. Reflections of educa-tors that teach TRIZ and KBI to students from mechanical, electrical, process engineering, and business administration are presented.
The comprehensive assessment method includes 80 innovation performance parameters and 10 key indicators of innovation capability, such as innovation process performance, innovating system performance, market and customer orientation, technology orientation, creativity, leadership, communication and knowledge management, risk and cost management, innovative climate, and innovation competences. The cross-industry study identifies parameters critical for innovation success and reveals different innovation performance patterns in companies.
CONTEXT
The paper addresses the needs of medium and small businesses regarding qualification of R&D specialists in the interdisciplinary cross-industry innovation, which promises a considerable reduction of investments and R&D expenditures. The cross-industry innovation is commonly understood as identification of analogies and transfer of technologies, processes, technical solutions, working principles or business models between industrial sectors. However, engineering graduates and specialists frequently lack the advanced skills and knowledge required to run interdisciplinary innovation across the industry boundaries.
PURPOSE
The study compares the efficiency of the cross-industry innovation methods in one semester project-oriented course. It identifies the individual challenges and preferred working techniques of the students with different prior knowledge, sets of experiences, and cultural contexts, which require attention by engineering educators.
APPROACH
Two parallel one-semester courses were offered to the mechanical and process engineering students enrolled in bachelor’s and master’s degree programs at the faculty of mechanical and process engineering. The students from different years of study were working in 12 teams of 3…6 persons each on different innovation projects, spending two hours a week in the classroom and additionally on average two hours weekly on their project research. Students' feedback and self-assessments concerning gained skills, efficiency of learned tools and intermediate findings were documented, analysed, and discussed regularly along the course.
RESULTS
Analysis of numerous student projects allows to compare and to select the tools most appropriate for finding cross-industry solutions, such as thinking in analogies, web monitoring, function-oriented search, databases of technological effects and processes, special creativity techniques and others. The utilization of learned skills in practical innovation work strengthens the motivation of students and enhances their entrepreneurial competences. Suggested learning course and given recommendations help facilitate sustainable education of ambitious specialists.
CONCLUSIONS
The structured cross-industry innovation can be successfully run as a systematic process and learned in one semester course. The choice of the preferred working teqniques made by the students is affected by their prior knowledge in science, practical experience, and cultural contexts. Major outcomes of the students’ innovation projects such as feasibility, novelty and customer value of the concepts are primarily influenced by students’ engineering design skills, prior knowledge of the technologies, and industrial or business experience.
The production of potable water in dry areas nowadays is mainly done by the desalination of seawater. State of the art desalination plants usually are built with high production capacities and consume a lot of electrical energy or energy from primary resources such as oil. This causes difficulties in rural areas, where no infrastructure is available neither for the plants’ energy supply nor the distribution of the produced potable water. To address this need, small, self-sustaining and locally operated desalination plants came into the focus of research. In this work, a novel flash evaporator design is proposed which can be driven either by solar power or by low temperature waste heat. It offers low operation costs as well as easy maintenance. The results of an experimental setup operated with water at a feed flow rate of up to 1,600 l/h are presented. It is shown that the proof of concept regarding efficient evaporation as well as efficient gas-liquid separation is provided successfully. The experimental evaporation yield counts for 98 % of the vapor content that is expected from the vapor pressure curve of water. Neither measurements of the electrical conductivity of the gained condensate, nor the analysis of the vapor flow by optical methods show significant droplet entrainment, so there are no concerns regarding the purity of the produced condensate for the use as drinking water.
Die Erfindung betrifft ein Verfahren zur Kalibration einer Kamera (110) unter Nutzung eines Bildschirmes (120), wobei der Bildschirm (120) eine Menge von Bildpunkten (122) aufweist und die Kamera (110) eine Vielzahl von Pixeln (112) zur Darstellung des Bildes nutzt. Das Verfahren umfasst die folgenden Schritten (a) Darstellen zumindest eines Bildwertes (BW) in zumindest einem Bildpunkt (122) des Bildschirms (120) basierend auf einer Bildwertzuweisung; (b) Erfassen des zumindest einen Bildwertes (BW) durch einen Pixel (112a) der Kamera (110); und (c) Bestimmen der Position des zumindest einen Bildpunktes (122) auf dem Bildschirm (120) basierend auf dem zumindest einen erfassten Bildwert (BW) und der Bildwertzuweisung.
Die vorliegende Erfindung betrifft ein Verfahren zum digitalen Drucken einer Keramikfarbe auf einem Substrat, wobei die Keramik der Keramikfarbe auf mindestens den Schmelzpunkt der Keramik mittels eines Laserstrahls simultan zu dem Aufbringen der Keramikfarbe auf ein Substrat mittels eines Druckkopfes erwärmt wird. Weiterhin betrifft die vorliegende Erfindung auch die Verwendung eines Laserstrahls in einer Vorrichtung zum digitalen Drucken einer Keramikfarbe auf einem Substrat, wobei der Laserstrahl die Keramik der Keramikfarbe auf mindestens den Schmelzpunkt der Keramik simultan zu dem Aufbringen der Keramikfarbe auf ein Substrat mittels eines Druckkopfes der Vorrichtung erwärmt. Die vorliegende Erfindung betrifft weiterhin auch eine Vorrichtung zum digitalen Drucken einer Keramikfarbe auf einem Substrat, die einen Druckkopf zum Aufbringen einer Keramikfarbe auf ein Substrat sowie einen Laser zum Erwärmen der Keramik der Keramikfarbe auf mindestens den Schmelzpunkt der Keramik mittels eines Laserstrahls umfasst.
Die vorliegende Erfindung betrifft ein Verfahren zum digitalen Drucken einer Keramikfarbe auf einem Substrat, wobei die Keramik der Keramikfarbe auf mindestens den Schmelzpunkt der Keramik mittels eines Laserstrahls simultan zu dem Aufbringen der Keramikfarbe auf ein Substrat mittels eines Druckkopfes erwärmt wird. Weiterhin betrifft die vorliegende Erfindung auch die Verwendung eines Laserstrahls in einer Vorrichtung zum digitalen Drucken einer Keramikfarbe auf einem Substrat, wobei der Laserstrahl die Keramik der Keramikfarbe auf mindestens den Schmelzpunkt der Keramik simultan zu dem Aufbringen der Keramikfarbe auf ein Substrat mittels eines Druckkopfes der Vorrichtung erwärmt. Die vorliegende Erfindung betrifft weiterhin auch eine Vorrichtung zum digitalen Drucken einer Keramikfarbe auf einem Substrat, die einen Druckkopf zum Aufbringen einer Keramikfarbe auf ein Substrat sowie einen Laser zum Erwärmen der Keramik der Keramikfarbe auf mindestens den Schmelzpunkt der Keramik mittels eines Laserstrahls umfasst.
Numerous 2,5-dimethoxy-N-benzylphenethylamines (NBOMe), carrying a variety of lipophilic substituents at the 4-position, are potent agonists at 5-hydroxytryptamine (5HT2A ) receptors and show hallucinogenic effects. The present study investigated the metabolism of 25D-NBOMe, 25E-NBOMe, and 25N-NBOMe using the microsomal model of pooled human liver microsomes (pHLM) and the microbial model of the fungi Cunninghamella elegans (C. elegans). Identification of metabolites was performed using liquid chromatography-high resolution-tandem mass spectrometry (LC-HR-MS/MS) with a quadrupole time-of-flight (QqToF) instrument. In total, 36 25D-NBOMe phase I metabolites, 26 25E-NBOMe phase I metabolites and 24 25N-NBOMe phase I metabolites were detected and identified in pHLM. Furthermore, 14 metabolites of 25D-NBOMe, 11 25E-NBOMe metabolites, and nine 25N-NBOMe metabolites could be found in C. elegans. The main biotransformation steps observed were oxidative deamination, oxidative N-dealkylation also in combination with hydroxylation, oxidative O-demethylation possibly combined with hydroxylation, oxidation of secondary alcohols, mono- and dihydroxylation, oxidation of primary alcohols, and carboxylation of primary alcohols. Additionally, oxidative di-O-demethylation for 25E-NBOMe and reduction of the aromatic nitro group and N-acetylation of the primary aromatic amine for 25N-NBOMe took place. The resulting 25N-NBOMe metabolites were unique for NBOMe compounds. For all NBOMes investigated, the corresponding 2,5-dimethoxyphenethylamine (2C-X) metabolite was detected. This study reports for the first time 25X-NBOMe N-oxide metabolites and hydroxylamine metabolites, which were identified for 25D-NBOMe and 25N-NBOMe and all three investigated NBOMes, respectively. C. elegans was capable of generating all main biotransformation steps observed in pHLM and might therefore be an interesting model for further studies of new psychoactive substances (NPS) metabolism.
We present an electrochemical model of a lithium iron phosphate/graphite (LFP/C6) cell that includes combined aging mechanisms: (i) Electrochemical formation of the solid electrolyte interphase (SEI) at the anode, leading to loss of lithium inventory, (ii) breaking of the SEI due to volume changes of the graphite particles, causing accelerated SEI growth, and (iii) loss of active material due to of loss percolation of the liquid electrolyte resulting from electrode dry-out. The latter requires the introduction of an activity-saturation relationship. A time-upscaling methodology is developed that allows to simulate large time spans (thousands of operating hours). The combined modeling and simulation framework is able to predict calendaric and cyclic aging up to the end of life of the battery cells. The aging parameters are adjusted to match literature calendaric and cyclic aging experiments, resulting in quantitative agreement of simulated nonlinear capacity loss with experimental data. The model predicts and provides an interpretation for the dependence of capacity loss on temperature, cycling depth, and average SOC. The introduction of a percolation threshold in the activity-saturation relationship allows to capture the strong nonlinearity of aging toward end of life (“sudden death”).
With the need for automatic control based supervisory controllers for complex energy systems, comes the need for reduced order system models representing not only the non-linear behaviour of the components but also certain unknown process dynamics like their internal control logic. At the Institute of Energy Systems Technology in Offenburg we have built a real-life microscale trigeneration plant and present in this paper a rational modelling procedure that satisfies the necessary characteristics for models to be applied in model predictive control for grid-reactive optimal scheduling of this complex energy system. These models are validated against experimental data and the efficacy of the methodology is discussed. Their application in the future for the optimal scheduling problem is also briefly motivated.
Im Rahmen der Konstruktionsausbildung an der Hochschule Offenburg wird die Lehre im Fach Technische Dokumentation fortlaufend optimiert. In der vorliegenden Laborstudie wurde das visuelle Wahrnehmen von 34 Maschinenbaustudierenden (2w + 32m) im Alter von 19 bis 29 Jahren mithilfe der Eye-Tracking-Technik und einer Videokamera bei der Analyse einer Baugruppenzeichnung beobachtet.
A Validated Quantification of Sudan Red Dyes in Spicery using TLC and a 16-bit Flatbed Scanner
(2018)
We present a video-densitometric quantification method for Sudan red dyes in spices and spice mixtures, separated by TLC. Application was done band-wise in small dots using a 5 μL glass pipette. For separation, the RP-18 plates (20 × 20 cm with fluorescent dye; Merck, Germany, 1.05559) were developed in a vertical developing chamber without vapor saturation from the starting point to a distance of 70 mm by using acetonitrile, methanol, and aqueous ammonia solution (25%; 8 + 1.8 + 0.2, v/v) as mobile phase. The quantification is based on direct measurements using an inexpensive 16-bit flatbed scanner for color measurements (in red, green, and blue). Evaluation of only the green channel makes the measurements very specific. For linearization, an extended Kubelka-Munk expression for data transformation was used. The range of linearity covers more than two magnitudes and lies between 20 and 500 ng. The extraction from a 2 g sample with acetonitrile, evaporation, and reconstitution to 200 μL with methanol and the band-wise application (7 mm) of a 10 μL sample allows a statistically defined LOD of less than 500 ppb of Sudan red dyes. To perform the analysis, a separation chamber, RP-18 plates, 5 μL glass pipettes, and a 16-bit flatbed scanner for 105 € are needed; therefore, the separation method is inexpensive, fast, and reliable.
We present a planar chromatographic separation method for the phytoestrogenic active compound equol, separated on RP-18 W (Merck, 1.14296) phase. It could be shown that an ethanolic cattle manure extract contains this phytoestrogenic active compound to a larger amount. As solvents for the mobile phase, hexane, ethyl acetate, and acetone (45:15:10, v/v); acetone and water (15:10, v/v); and n-hexane, CH2Cl2, ethyl acetate, methanol, and formic acid (40:40:20:5:1, v/v) have been used. After separation, a modified yeast estrogen screen (YES) test was applied, using the yeast strain Saccharomyces cerevisiae BJ3505 containing an estrogen receptor. Its activation by equol induces the reporter gene lacZ which encodes the enzyme β-galactosidase. The enzyme activity is measured directly on the TLC plate by using the substrate MUG (4-methylumbelliferyl-β-d-galactopyranoside) or the substrate X-β-Gal (5-bromo-4-chloro-3-indoxyl-β-d-galactopyranoside). β-Galactosidase cleaves MUG into a fluorescing compound. X-β- Gal is also hydrolyzed and then oxidized by oxygen forming the deep-blue dye 5,5′-dibromo-4,4′-dichloro-indigo. Both reactions in combination with a thin-layer chromatography (TLC) separation allow very specific detecting of equol in cattle manure, although that is a very challenging matrix. Preliminary results show that the average content of equol in liquid manure is roughly 60 μg g−1. The value for urine is 50 μg mL−1.
Freiwillige Fachtutorien erreichen aus unterschiedlichen Gründen nicht alle Studierenden. Allein der subjektive Eindruck, dass zu wenige Ressourcen seitens der Hochschule (Übungsräume, studentische Tutoren, lückenlose Stundenplanpassung) oder der Studierenden (Zeit, Motivation) zur Verfügung stünden, führt zu Absenzen bei freiwilligen Präsenztutorien. Um die empfundenen und realen Begrenzungen dieser Veranstaltungen zu verringern, wurden für den Studiengang Maschinenbau die Musterlösungen der Übungsaufgaben Physik und Mathematik in Form von Videoclips erstellt und über die Lernplattform Moodle für alle Studierende des Semesters bereitgestellt. Die Clips beziehen sich jeweils auf eine Teilaufgabe und besitzen die Länge eines typischen Youtube-Tutorials. In etwa 5 Minuten bieten sie dem Zuschauer einen Lösungsweg zu den jeweiligen Übungsaufgaben. Die Studierenden können die Clips alternativ oder ergänzend zur Präsenzveranstaltung nutzen. Bei der Erstellung der Clips wurde auf den Einsatz von Spezialeffekten wie Animationen etc. zugunsten einer effizienten Produktion verzichtet, so dass eine einzelne Lehrperson pro Stunde etwa 10 bis 20 Minuten Videoclips aufzeichnen kann. Die Auswertung der Zugriffszahlen auf die Clip-Dateien ermöglicht eine aufgabengenaue Ermittlung der aktiven Nutzer. Im Betrag wird eine vorläufige Auswertung der Teilnehmerzahl und der Korrelation zwischen Klausurergebnis und Nutzungsgrad präsentiert.
Hot work tools are subjected to complex thermal and mechanical loads during hot forming processes. Locally, the stresses can exceed the material’s yield strength in highly loaded areas as e.g. in small radii in die cavities. To sustain the high loads, the hot forming tools are typically made of martensitic hot work steels. While temperatures for annealing of the tool steels usually lie in the range between 400 and 600 °C, the steels may experience even higher temperatures during hot forming, resulting in softening of the material due to coarsening of strengthening particles. In this paper, a temperature dependent cyclic plasticity model for the martensitic hot work tool steel 1.2367 (X38CrMoV5-3) is presented that includes softening due to particle coarsening and that can be applied in finite-element calculations to assess the effect of softening on the thermomechanical fatigue life of hot work tools. To this end, a kinetic model for the evolution of the mean size of secondary carbides based on Ostwald ripening is coupled with a cyclic plasticity model with kinematic hardening. Mechanism-based relations are developed to describe the dependency of the mechanical properties on carbide size and temperature. The material properties of the mechanical and kinetic model are determined on the basis of tempering hardness curves as well as monotonic and cyclic tests.
In this paper, the temperature dependent cyclic mechanical properties of the martensitic hot work tool steel 1.2367 after tempering are investigated. To this end, hardness measurements as well as monotonic and cyclic tests at temperatures in the range from room temperature to 650 °C are performed on material tempered for different tempering times and temperatures. To describe the observed time and temperature dependent softening during tempering a kinetic model for the evolution of the mean size of secondary carbides based on Ostwald ripening is developed. Furthermore, mechanism-based as well as phenomenological relations for the cyclic mechanical properties of the Ramberg-Osgood model depending on carbide size and temperature are introduced. A good overall agreement of the measured and the calculated stress-strain hysteresis loops for different temperatures and heat treatments is obtained using the determined material properties of the kinetic and mechanical model.
In this paper the yield surface of a recently presented microstructure-based volume element of the gray cast iron material GJL-250 is assessed after different plastic loading histories. The evolution of the yield surface is investigated for different volumetric, deviatoric and uniaxial loadings. The micromechanical material properties of the metallic matrix and the graphite inclusions are validated by means experimental stress-strain hysteresis loops. The metallic matrix is modeled as elastic-plastic with a non-linear kinematic hardening law. The graphite inclusions are described by means of a volumetric strain state dependent Young’s modulus. The results show that the shape of the yield surface does not change significantly in comparison to the initial yield surface after pure deviatoric loadings. After volumetric loadings, the dependence of the material on the Lode angle is significantly reduced. Uniaxial tensile preloadings result in a deformed yield surface, whereby the magnitude of the deformation depends on the applied load. Uniaxial preloadings to compression do not change the shape of the initial yield surface.
Membrane distillation (MD) is a thermal separation process which possesses a hydrophobic, microporous
membrane as vapor space. A high potential application for MD is the concentration of hypersaline brines, such as
e.g. reverse osmosis retentate or other saline effluents to be concentrated to a near saturation level with a Zero
Liquid Discharge process chain. In order to further commercialize MD for these target applications, adapted MD
module designs are required along with strategies for the mitigation of membrane wetting phenomena. This
work presents the experimental results of pilot operation with an adapted Air Gap Membrane Distillation
(AGMD) module for hypersaline brine concentration within a range of 0–240 g NaCl /kg solution. Key performance
indicators such as flux, GOR and thermal efficiency are analyzed. A new strategy for wetting mitigation
by active draining of the air gap channel by low pressure air blowing is tested and analyzed. Only small reductions
in flux and GOR of 1.2% and 4.1% respectively, are caused by air sparging into the air gap channel.
Wetting phenomena are significantly reduced by avoiding stagnant distillate in the air gap making the air blower
a seemingly worth- while additional system component.
In der vorliegenden Arbeit werden mikrostruktur- und mechanismusbasierte Werkstoffmodelle zur Beschreibung des Deformations- und Lebensdauerverhaltens von thermomechanisch beanspruchten Graugusswerkstoffen vorgestellt.
Mit den Modellen wird das zyklische Deformations- und Lebensdauerverhalten verschiedener Graugusswerkstoffe für einachsig belastete Ermüdungsproben und für die Zylinderköpfe von Dieselmotoren vorhergesagt.
VDI Standard 4521: Status
(2016)
VDI Guideline 4521 Part 1: “Inventive problem solving with TRIZ: Part 1 – Fundamentals and definitions” has been published on 2015-04-01. The standard will sharpen the image of TRIZ, facilitate cooperation, and support studying and teaching. It is not a textbook but concisely summarizes basic assumptions of TRIZ and its terminology. It gives an overview on specific methods and tools which will be described in the following parts.
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.
In this paper, the correlation of the cyclic J-integral, ΔJ, and the cyclic crack-tip opening displacement, ΔCTOD, is studied in the presence of crack closure to assess the question if ΔJ describes the crack-tip opening displacement in this case. To this end, a method is developed to evaluate ΔJ numerically within finite-element calculations. The method is validated for an elastic–plastic material that exhibits Masing behavior. Different strain ranges and strain ratios are considered under fully plastic cyclic conditions including crack closure. It is shown that the cyclic J-integral is the parameter to determine the cyclic crack-tip opening displacement even in cases where crack closure is present.
In this paper, the initial multiaxial yield behavior of three different gray cast iron materials with lamellar shaped graphite inclusions is numerically investigated by means of the finite-element method. Therefore, volume elements including the real microstructure of the materials are loaded bi- and triaxially beyond macroscopic yield. The shape of the obtained yield surfaces are compared to the surfaces of four continuum models which, amongst others, are proposed in literature to describe the inelastic behavior of gray cast iron with lamellar shaped graphite inclusions. It is found that the presented continuum models and the macroscopic yield surfaces obtained with microstructure-based finite-element models deviate. Furthermore, the initial inelastic flow direction is computed at the onset of macroscopic yielding. The analysis show that the inelastic flow is normal to the yield surface.
Demand Side Management for Thermally Activated Building Systems based on Multiple Linear Regression
(2015)
Since 2003, most European countries established heat health warning systems to alert the population to heat load. Heat health warning systems are based on predicted meteorological conditions outdoors. But the majority of the European population spends a substantial amount of time indoors, and indoor thermal conditions can differ substantially from outdoor conditions. The German Meteorological Service (Deutscher Wetterdienst, DWD) extended the existing heat health warning system (HHWS) with a thermal building simulation model to consider heat load indoors. In this study, the thermal building simulation model is used to simulate a standardized building representing a modern nursing home, because elderly and sick people are most sensitive to heat stress. Different types of natural ventilation were simulated. Based on current and future test reference years, changes in the future heat load indoors were analyzed. Results show differences between the various ventilation options and the possibility to minimize the thermal heat stress during summer by using an appropriate ventilation method. Nighttime ventilation for indoor thermal comfort is most important. A fully opened window at nighttime and the 2-h ventilation in the morning and evening are more sufficient to avoid heat stress than a tilted window at nighttime and the 1-h ventilation in the morning and the evening. Especially the ventilation in the morning seems to be effective to keep the heat load indoors low. Comparing the results for the current and the future test reference years, an increase of heat stress on all ventilation types can be recognized.
Packed beds serve as thermal energy storages (TES) and heat exchangers (HEX) in different technological applications. In this paper, a general heterogeneous model of heat transfer in packed beds is developed. It is implemented by lumped element formulation in object-oriented modeling language Modelica and is successful validated with data sets taken from two different experiments reported in literature.
The main advantages of the introduced model are the general, theory-based approach and the lumped element formulation in Modelica. The first point mentioned above should allow to simulate a packed bed TES/HEX without the necessity applying measured data for model calibration or to apply specific heat transfer correlations with restricted application. The second point establishes the possibility to integrate the TES/HEX model within plant models of larger scale without increasing the simulation time drastically.
Der Endkundenvertrieb ist für die Bewahrung und Weiterentwicklung des Kundenstamms eines Energieversorgers essenziell. Doch um knappe Mittel im Vertrieb möglichst wirkungsvoll einsetzen zu können, wird Wissen darüber benötigt, wie sich die durchschnittlich erzielbaren Strompreise und die zu erwartende Kundenbindungsdauer zwischen verschiedenen Vertriebskanälen unterscheiden. Leitet man anhand dieser Informationen den Wert eines Kunden je Vertriebskanal ab, lässt sich treffsicherer über einzusetzende Marketing-Budgets entscheiden.
This paper reports on the evolution of cracks in the cylinder heads of a large V8 Diesel engine during cyclic engine tests. The observations are compared with the predictions of a lifetime model for combined thermo-mechanical (TMF) and high cycle fatigue (HCF) loading, which is based on a fracture mechanics analysis of microcrack growth in viscoplastic solids and assumes that the crack advance per cycle is proportional to the cyclic crack tip opening displacement. Since the material of the cylinder heads, the cast iron EN-GJV450, exhibits the typical features of cast iron, namely pressure dependence of the yield stress, dilatancy and tension-compression asymmetry, the Gurson model is applied and combined with the viscoplastic Chaboche model. This constitutive model together with the lifetime model is implemented into a finite element code as a user defined material routine. Published model parameters for the considered cast iron are used to carry out the simulation of the engine test. This simulation comprises a CFD analysis to determine the heat transfer coefficients, a thermal analysis of the load cycle and the mechanical analysis. The thermal analysis reproduces the temperatures at various measuring points sufficiently accurately. Finally, the mechanical analysis predicts the location and orientation of the cracks in the valve bridges correctly in all cases. However, the lifetime predictions are rather conservative compared to the tests (by a factor of 1 to 5 in lifetime). This is discussed and explained by the fact that the cracks were detected in the tests only when they had already spread over a substantial fraction of the valve bridge width. To describe this situation a long-crack analysis would be necessary, which is not yet included in the applied lifetime model.
Techno-economic comparison of membrane distillation and MVC in a zero liquid discharge application
(2018)
Membrane distillation (MD) is a thermally driven membrane process for the separation of vapour from a liquid stream through a hydrophobic, microporous membrane. However, a commercial breakthrough on a large scale has not been achieved so far. Specific developments on MD technology are required to adapt the technology for applications in which its properties can potentially outshine state of the art technologies such as standard evaporation. In order to drive these developments in a focused manner, firstly it must be shown that MD can be economically attractive in comparison to state of the art systems. Thus, this work presents a technological design and economic analysis for AGMD and v-AGMD for application in a zero liquid discharge (ZLD) process chain and compares it to the costs of mechanical vapour compression (MVC) for the same application. The results show that MD can potentially be ~40% more cost effective than MVC for a system capacity of 100 m3/day feed water, and up to ~75% more cost effective if the MD is driven with free waste heat.
Grundzüge der Strömungslehre
(2018)
Dieses ausgereifte Lehrbuch bringt in prägnant kurzer und mathematisch verständlicher Darstellung die strömungstechnischen Grundlagen. In der aktuellen Auflage wurde ein Abschnitt zu Dissipation und Viskosen Potentialströmungen ergänzt. Aufgaben mit Lösungen helfen den Lernstoff richtig anzuwenden und fördern das Verständnis.
Photovoltaics Energy Prediction Under Complex Conditions for a Predictive Energy Management System
(2015)
Sustainable Aspects force a building manager to continuous observation of actual states and developments concerning building use, energy and media flows.In the presented approach a communication structure was built up to use different software applications and tools in order to optimize the operation of the building.
Intelligent und nachhaltig
(2013)
Die starke Nachfrage für wirtschaftliche und technische Lösungen zur Umsetzung der Energiewende wirkt sich auch auf Projektinitiativen der Forschungsgruppen am Institut für Energiesystemtechnik (INES) der Hochschule Offenburg aus. Am Campus Nord entsteht seit 2012 ein intelligentes Energienetz als Reallabor, das als Teil eines Smart Grid betrieben werden kann.
HiSiMo cast irons are frequently used as material for high temperature components in engines as e.g. exhaust manifolds and turbo chargers. These components must withstand severe cyclic mechanical and thermal loads throughout their life cycle. The combination of thermal transients with mechanical load cycles results in a complex evolution of damage, leading to thermomechanical fatigue (TMF) of the material and, after a certain number of loading cycles, to failure of the component. In Part I of the paper, a fracture mechanics model for TMF life prediction was developed based on results of uniaxial tests. In this paper (Part II), the model is formulated for three-dimensional stress states, so that it can be applied in a post-processing step of a finite-element analysis. To obtain reliable stresses and (time dependent plastic) strains in the finite-element calculation, a time and temperature dependent plasticity model is applied which takes non-linear kinematic hardening into account. The material properties of the model are identified from the results of the uniaxial test. The plasticity model and the TMF life model are applied to assess the lifetime of an exhaust manifold.
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.