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In this paper fatigue crack closure under in-phase and out-of-phase thermomechanical fatigue (TMF) loading is studied using a temperature dependent strip yield model. It is shown that fatigue crack closure is strongly influenced by the phase relation between mechanical loading and temperature, if the temperature difference goes along with a temperature dependence of the yield stress. In order to demonstrate the effect of the temperature dependent yield stress, the influence of in-phase and out-of-phase TMF loading is studied for a polycrystalline nickel-base superalloy. By using a mechanism based lifetime model, implications for fatigue lives are demonstrated.
A crack opening stress equation for in-phase and out-of-phase thermomechanical fatigue loading
(2016)
In this paper, a crack opening stress equation for in-phase and out-of-phase thermomechanical fatigue (TMF) loading is proposed. The equation is derived from systematic calculations of the crack opening stress with a temperature dependent strip yield model for both plane stress and plane strain, different load ratios and different ratios of the temperature dependent yield stress in compression and tension. Using a load ratio scaled by the ratio of the yield stress in compression and tension, the equation accounts for the effect of the temperature dependent yield stress and the constraint on the crack opening stress. Based on the scaling relation established in this paper, Newman's crack opening stress equation for isothermal loading is enabled to predict the crack opening stress under TMF loading.
Micro gas turbines (MGTs) are regarded as combined heat and power (CHP) units which offer high fuel utilization and low emissions. They are applied in decentralized energy neration.
To facilitate the planning process of energy systems, namely in the context of the increasing application of optimization techniques, there is a need for easy-to-parametrize component models with sufficient accuracy which allow a fast computation. In this paper, a model is proposed where the non-linear part load characteristics of the MGT are linearized by means of physical insight of the working principles of turbomachinery. Further, it is shown that the model can be parametrized by the data usually available in spec sheets. With this model a uniform description of MGTs from several manufacturers
covering an electrical power range from 30kW to 333kW can be obtained. The MGT model was
implemented by means of Modelica/Dymola. The resulting MGT system model, comprising further heat exchangers and hydraulic components, was validated using the experimental data of a 65kW MGT from a trigeneration energy system.
Polygeneration systems are a key technology for the reduction of primary energy usage and emissions. High costs, lack of flexibility and effort for parameterization hinder the wide usage of modeling tools during their conceptual design. This paper describes how planning tools can be structured for the conceptual design phase where only little information is available to the planner. A library concept was developed using the principles of object-oriented modeling to address the flexibility issue. With respect to cost and expandability, the open-source modeling language Modelica was chosen. Furthermore, easy-to-parameterize component models were developed. In addition to the improved library concept and novel component models, an easy-to-adapt control concept is proposed. The component models were validated and the applicability of the library was demonstrated by means of an example. It was shown that the data usually obtained from spec sheets are sufficient to parameterize the models. In addition to this, the control concept was approved.
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.
Tryptamines can occur naturally in plants, mushrooms, microbes, and amphibians. Synthetic tryptamines are sold as new psychoactive substances (NPS) because of their hallucinogenic effects. When it comes to NPS, metabolism studies are of crucial importance, due to the lack of pharmacological and toxicological data. Different approaches can be taken to study in vitro and in vivo metabolism of xenobiotica. The zygomycete fungus Cunninghamella elegans (C. elegans) can be used as a microbial model for the study of drug metabolism. The current study investigated the biotransformation of four naturally occurring and synthetic tryptamines [N,N‐Dimethyltryptamine (DMT), 4‐hydroxy‐N‐methyl‐N‐ethyltryptamine (4‐HO‐MET), N,N‐di allyl‐5‐methoxy tryptamine (5‐MeO‐DALT) and 5‐methoxy‐N‐methyl‐N‐isoporpoyltryptamine (5‐MeO‐MiPT)] in C. elegans after incubation for 72 hours. Metabolites were identified using liquid chromatography–high resolution–tandem mass spectrometry (LC–HR–MS/MS) with a quadrupole time‐of‐flight (QqTOF) instrument. Results were compared to already published data on these substances. C. elegans was capable of producing all major biotransformation steps: hydroxylation, N‐oxide formation, carboxylation, deamination, and demethylation. On average 63% of phase I metabolites found in the literature could also be detected in C. elegans. Additionally, metabolites specific for C. elegans were identified. Therefore, C. elegans is a suitable complementary model to other in vitro or in vivo methods to study the metabolism of naturally occurring or synthetic tryptamines.
Seven cell design concepts for aqueous (alkaline) lithium–oxygen batteries are investigated using a multi-physics continuum model for predicting cell behavior and performance in terms of the specific energy and specific power. Two different silver-based cathode designs (a gas diffusion electrode and a flooded cathode) and three different separator designs (a porous separator, a stirred separator chamber, and a redox-flow separator) are compared. Cathode and separator thicknesses are varied over a wide range (50 μm–20 mm) in order to identify optimum configurations. All designs show a considerable capacity-rate effect due to spatiotemporally inhomogeneous precipitation of solid discharge product LiOH·H2O. In addition, a cell design with flooded cathode and redox-flow separator including oxygen uptake within the external tank is suggested. For this design, the model predicts specific power up to 33 W/kg and specific energy up to 570 Wh/kg (gravimetric values of discharged cell including all cell components and catholyte except housing and piping).
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.
Im Automobilbau bietet der Einsatz der Multimaterialbauweise ein signifikantes Potenzial zur Gewichtsreduktion. Zugleich erfordert diese Bauweise eine große Anzahl von Fügeverfahren für die Verbindung der unterschiedlichen Werkstoffe und Werkstoffklassen. Dabei muss eine Vielzahl an konstruktiven und materialseitigen Anforderungen berücksichtigt werden. Um in diesem Auswahlprozess den Aspekt des Leichtbaus beim Fügeverfahren selbst systematisch zu integrieren, wurde eine Methodik entwickelt, welche die Fügeverfahren im Hinblick auf ihr jeweiliges Leichtbaupotenzial bewertet.
The aim of this review was to determine whether smartphone applications are reliable and valid to measure range of motion (RoM) in lower extremity joints. A literature search was performed up to October 2020 in the databases PubMed and Cochrane Library. Studies that reported reliability or validity of smartphone applications for RoM measurements were included. The study quality was assessed with the QUADAS-2 tool and baseline information, validity and reliability were extracted. Twenty-five studies were included in the review. Eighteen studies examined knee RoM, whereof two apps were analysed as having good to excellent reliability and validity for knee flexion (“DrGoniometer”, “Angle”) and one app showed good results for knee extension (“DrGoniometer”). Eight studies analysed ankle RoM. One of these apps showed good intra-rater reliability and excellent validity for dorsiflexion RoM (“iHandy level”), another app showed excellent reliability and moderate validity for plantarflexion RoM (“Coach’s Eye”). All other apps concerning lower extremity RoM had either insufficient results, lacked study quality or were no longer available. Some apps are reliable and valid to measure RoM in the knee and ankle joint. No app can be recommended for hip RoM measurement without restrictions.
High temperature components in internal combustion engines and exhaust systems must withstand severe mechanical and thermal cyclic loads throughout their lifetime. The combination of thermal transients and mechanical load cycling results in a complex evolution of damage, leading to thermomechanical fatigue (TMF) of the material. Analytical tools are increasingly employed by designers and engineers for component durability assessment well before any hardware testing. The DTMF model for TMF life prediction, which assumes that micro-crack growth is the dominant damage mechanism, is capable of providing reliable predictions for a wide range of high-temperature components and materials in internal combustion engines. Thus far, the DTMF model has employed a local approach where surface stresses, strains, and temperatures are used to compute damage for estimating the number of cycles for a small initial defect or micro-crack to reach a critical length. In the presence of significant gradients of stresses, strains, and temperatures, the use of surface field values could lead to very conservative estimates of TMF life when compared with reported lives from hardware testing. As an approximation of gradient effects, a non-local approach of the DTMF model is applied. This approach considers through-thickness fields where the micro-crack growth law is integrated through the thickness considering these variable fields. With the help of software tools, this method is automated and applied to components with complex geometries and fields. It is shown, for the TMF life prediction of a turbocharger housing, that the gradient correction using the non-local approach leads to more realistic life predictions and can distinguish between surface cracks that may arrest or propagate through the thickness and lead to component failure.
A complete thermomechanical fatigue (TMF) life prediction methodology is developed for predicting the TMF life of cast iron cylinder heads for efficient heavy duty internal combustion engines. The methodology uses transient temperature fields as thermal loads for the non-linear structural finite-element analysis (FEA). To obtain reliable stress and strain histories in the FEA for cast iron materials, a time and temperature dependent plasticity model which accounts for viscous effects, non-linear kinematic hardening and tensioncompression asymmetry is required. For this purpose a unified elasto-viscoplastic Chaboche model coupled with damage is developed and implemented as a user material model (USERMAT) in the general purpose FEA program ANSYS. In addition, the mechanismbased DTMF model for TMF life prediction developed in Part I of the paper is extended to three-dimensional stress states under transient non-proportional loading conditions. The material properties of the plasticity model are determined for lamellar graphite cast iron GJL250 and vermicular graphite cast iron GJV450 from isothermal and non-isothermal uniaxial tests. The methodology is applied to obtain a TMF life prediction on two cast iron cylinder heads for heavy duty diesel engine applications made from both cast iron materials. It is shown that the life predictions using the developed methodology correlate very well with observed lives from two bench tests in terms of location as well as number of cycles to failure.
Phosphate-based inorganic–organic hybrid nanoparticles (IOH-NPs) with the general composition [M]2+[Rfunction(O)PO3]2– (M = ZrO, Mg2O; R = functional organic group) show multipurpose and multifunctional properties. If [Rfunction(O)PO3]2– is a fluorescent dye anion ([RdyeOPO3]2–), the IOH-NPs show blue, green, red, and near-infrared fluorescence. This is shown for [ZrO]2+[PUP]2–, [ZrO]2+[MFP]2–, [ZrO]2+[RRP]2–, and [ZrO]2+[DUT]2– (PUP = phenylumbelliferon phosphate, MFP = methylfluorescein phosphate, RRP = resorufin phosphate, DUT = Dyomics-647 uridine triphosphate). With pharmaceutical agents as functional anions ([RdrugOPO3]2–), drug transport and release of anti-inflammatory ([ZrO]2+[BMP]2–) and antitumor agents ([ZrO]2+[FdUMP]2–) with an up to 80% load of active drug is possible (BMP = betamethason phosphate, FdUMP = 5′-fluoro-2′-deoxyuridine 5′-monophosphate). A combination of fluorescent dye and drug anions is possible as well and shown for [ZrO]2+[BMP]2–0.996[DUT]2–0.004. Merging of functional anions, in general, results in [ZrO]2+([RdrugOPO3]1–x[RdyeOPO3]x)2– nanoparticles and is highly relevant for theranostics. Amine-based functional anions in [MgO]2+[RaminePO3]2– IOH-NPs, finally, show CO2 sorption (up to 180 mg g–1) and can be used for CO2/N2 separation (selectivity up to α = 23). This includes aminomethyl phosphonate [AMP]2–, 1-aminoethyl phosphonate [1AEP]2–, 2-aminoethyl phosphonate [2AEP]2–, aminopropyl phosphonate [APP]2–, and aminobutyl phosphonate [ABP]2–. All [M]2+[Rfunction(O)PO3]2– IOH-NPs are prepared via noncomplex synthesis in water, which facilitates practical handling and which is optimal for biomedical application. In sum, all IOH-NPs have very similar chemical compositions but can address a variety of different functions, including fluorescence, drug delivery, and CO2 sorption.
Human interaction frequently includes decision-making processes during which interactants call on verbal and non-verbal resources to manage the flow of interaction. In 2017, Stevanovic et al. carried out pioneering work, analyzing the unfolding of moment-by-moment dynamics by investigating the behavioral matching during search and decision-making phases. By studying the similarities in the participant's body sway during a conversation task in Finnish, the authors showed higher behavioral matching during decision phases than during search phases. The purpose of this research was to investigate the whole-body sway and its coordination during joint search and decision-making phases as a replication of the study by Stevanovic et al. (2017) but based on a German population. Overall, 12 dyads participated in this study and were asked to decide on 8 adjectives, starting with a pre-defined letter, to describe a fictional character. During this joint-decision task (duration: 206.46 ± 116.08 s), body sway of both interactants was measured using a 3D motion capture system and center of mass (COM) accelerations were computed. Matching of body sway was calculated using a windowed cross correlation (WCC) of the COM accelerations. A total of 101 search and 101 decision phases were identified for the 12 dyads. Significant higher COM accelerations (5.4*10−3 vs. 3.7*10−3 mm/s2, p < 0.001) and WCC coefficients (0.47 vs. 0.45, p = 0.043) were found during decision-making phases than during search phases. The results suggest that body sway is one of the resources humans use to communicate the arrival at a joint decision. These findings contribute to a better understanding of interpersonal coordination from a human movement science perspective.
Die Zuverlässigkeit und Betriebssicherheit von Feldgeräten ist für den sicheren und wirtschaftlichen Betrieb prozesstechnischer Anlagen unerlässlich. Ein entscheidender Faktor ist die Widerstandskraft der Geräte gegen die herrschenden Umgebungsbedingungen. Durch Korrosionsschäden hervorgerufene Anlagenstillstände zeigen, dass diesem Thema nicht immer die notwendige Aufmerksamkeit gewidmet wird, obwohl die korrosionsbedingten wirtschaftlichen Schäden immens sind. Wie man mit dem Thema Korrosionsschutz ernsthaft umgehen kann, zeigt dieser Beitrag am Beispiel elektrischer Stellantriebe.
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!
Given the looming threats of climate change and the rapid worldwide urbanization, it is a necessity to prioritize the transition towards a carbon-free built environment. This research study provides a holistic digital methodology for parametric design of urban residential buildings with regard to the Mediterranean semi-arid climate zone of Morocco in the early design phase. The morphological parameters of the urban residential buildings, namely the buildings’ typology, the distance between buildings, the urban grid’s orientation, and the window-towall ratio, are evaluated in order to identify the key combinations of passive and active solar design strategies that determine the high energy performing configurations, based on the introduced Energy Performance Index (EPI), which is the ratio between solar BIPV production to maximum available installed BIPV capacity and the normalized thermal energy needs. Through an automated processing of 2187 iterations via Grasshopper, we simulate daylight autonomy, indoor thermal comfort and solar rooftop photovoltaic and building integrated photovoltaic (BIPV) energy potential. Then, we analyze the conflicting objectives of energy efficiency measures, active solar design strategies, and indoor visual comfort in the decision-making process that supports our goal of getting closer to net zero urban residential buildings. The digital workflow showed interesting trends in reaching a balanced equilibrium between performance metrics influenced by the contrasting impact of solar exposure on indoor daylight autonomy and thermal energy demand. Furthermore, the study’s findings indicate that it is possible to achieve an annual load match exceeding 66,56 % while simultaneously ensuring an acceptable visual indoor comfort (sDA higher than 0.4). The findings also highlight the important role of the BIPV system in shifting towards the net zero energy goal, by contributing up to 30 % of the overall solar energy output and covering up to 20 % of the yearly self-consumption. Moreover, the energy balance evaluation on an hourly basis indicates that BIPV system notably enhances the daily load cover factor by up to 5.5 %, particularly in the case of slab SN typology, throughout the different seasons. Graphical representations of the yearly, monthly and hourly load matches and the hourly energy balance of the best performing configurations provide a thorough understanding of the potential evolution of the urban energy system over time as a result of the gradual integration of active solar electricity production.
The DMFC is a promising option for backup power systems and for the power supply of portable devices. However, from the modeling point of view liquid-feed DMFC are challenging systems due to the complex electrochemistry, the inherent two-phase transport and the effect of methanol crossover. In this paper we present a physical 1D cell model to describe the relevant processes for DMFC performance ranging from electrochemistry on the surface of the catalyst up to transport on the cell level. A two-phase flow model is implemented describing the transport in gas diffusion layer and catalyst layer at the anode side. Electrochemistry is described by elementary steps for the reactions occurring at anode and cathode, including adsorbed intermediate species on the platinum and ruthenium surfaces. Furthermore, a detailed membrane model including methanol crossover is employed. The model is validated using polarization curves, methanol crossover measurements and impedance spectra. It permits to analyze both steady-state and transient behavior with a high level of predictive capabilities. Steady-state simulations are used to investigate the open circuit voltage as well as the overpotentials of anode, cathode and electrolyte. Finally, the transient behavior after current interruption is studied in detail.
Wirtschaftlichkeitsbetrachtung eines smarten Energiekonzepts für ein Bestandsquartier in Karlsruhe
(2023)
Die Transformation der Energieversorgung in Bestandsgebäuden ist für die Erreichung der Klimaziele im Gebäudesektor entscheidend. In einem modellhaften Quartiersprojekt in Karlsruhe-Durlach wird ein ‚smartes Energiekonzept‘, bestehend aus Wärmepumpen, Blockheizkraftwerk und PV-Anlagen mit lokalem Strom- und Wärmenetz umgesetzt und messtechnisch begleitet. Ziel ist dabei eine CO2-effiziente und wirtschaftliche Bereitstellung von Wärme und Strom.
In dem Artikel wird eine Wirtschaftlichkeitsbetrachtung für das Wärme- und Stromcontracting auf Basis der realen Investitionskosten sowie der gemessenen und berechneten Energieflüsse durchgeführt. Die Wärmegestehungskosten hängen neben den Investitionskosten von den energiewirtschaftlichen Rahmenbedingungen ab. Mit ansteigender CO2-Steuer werden mittelfristig Wärmegestehungskosten erreicht, die unter denen konventioneller Energiesysteme liegen. Dadurch bietet das integrierte Energiekonzept ein breites Anwendungspotenzial für städtische Bestandsquartiere außerhalb von Fernwärme-Gebieten.
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.
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.
Warmumformwerkzeuge unterliegen während des Betriebes komplexen thermischen und mechanischen Beanspruchungen. In kritischen Bereichen können dadurch lokal Spannungen entstehen, die die Fließgrenze überschreiten. Bei der Serienproduktion führt dies zu zyklischen plastischen Verformungen und zur thermomechanischen Ermüdung, welche die Lebensdauer der Warmumformwerkzeuge maßgeblich bestimmen kann. Zur Bewertung der thermomechanischen Ermüdung der Warmumformwerkzeuge gibt es jedoch heute keine etablierten Konzepte, da dieser Aspekt erst durch die Notwendigkeit einer höheren Ressourcen- und Energieeffizienz und optimierter Produktionsprozesse (beispielsweise im Rahmen von Industrie 4.0) eine höhere Aufmerksamkeit erreicht. In dieser Arbeit wird zum einen die aktuell industriell angewandte Vorgehensweise zur Auslegung von Warmumformwerkzeugen hinsichtlich der Lebensdauer erläutert. Des Weiteren wird ein Überblick über existierende Plastizitätsmodelle und Lebensdauermodelle gegeben. Dabei wird zwischen rein phänomenologischen und mechanismenbasierten Modellen unterschieden. Aus der betriebenen Recherche wird ersichtlich, dass weiterer Forschungsbedarf auf diesem Gebiet notwendig ist.
Mit längerfristigen Nutzerbefragungen in zwei unmittelbar benachbarten Bürogebäuden in Freiburg wurden das Temperaturempfinden der Nutzer und deren Zufriedenheit mit dem thermischen Raumkomfort zweimal täglich erfasst. Ein Bürogebäude wird im Sommer mit einem maschinellen Nachtlüftungskonzept konditioniert und das zweite verfügt über eine Betonkerntemperierung und eine Zu‐ und Abluftanlage. Auf Basis der vorhandenen Daten aus der Erhebung wurde mit Hilfe von Regressionsanalysen ein Modell zur Vorhersage der Komforttemperatur berechnet und mit den Modellen in DIN EN 15251 verglichen.
In 35 deutschen und 7 europäischen Büro- und Verwaltungsgebäuden wurden auf Basis von Monitoringkampagnen über mehrere Betriebsjahre Raum- und Außentemperaturwerte in zeitlich hoher Auflösung erfasst und der thermische Raumkomfort im Sommer standardisiert nach der Komfortnorm DIN EN 15251:2007-08 detailliert ausgewertet. Ergänzt wird die Auswertung um Kurzzeitmesskampagnen über zwei sehr warme Wochen im Sommer in unsanierten bzw. teilsanierten Bürogebäuden, errichtet im Zeitraum von 1960 bis 1975. Die untersuchten Gebäude mit ihrem jeweiligen Kühlkonzept lassen sich in sechs Kategorien einteilen: ohne Kühlung, passive, luftgeführte und wassergeführte Kühlung sowie Mixed-mode-Kühlung und Vollklimatisierung. Im Quervergleich aller Gebäude werden die Kühlkonzepte gleichermaßen nach dem thermischen Raumkomfort und thermischen Kühlenergiebezug bewertet. Detaillierte Komfortuntersuchungen nach der Europäischen Komfortnorm DIN EN 15251:2007-08 geben Hinweise auf die Wirksamkeit der eingesetzten Kühltechnologien in den jeweiligen Klimazonen. Daraus lassen sich Handlungsempfehlungen für die Planungspraxis und den Gebäudebetrieb ableiten.
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.
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.
Two closely related series of paddle-wheel-based triazolyl isophthalate MOFs are presented. Thermal and CO2 adsorption studies reveal network flexibility induced by alkyl substituents of the linker. By choice of the substituent, the pore volumes and pore diameters can be adjusted. Fine-tuning of the gate opening pressure and the hysteresis shape is possible by modulating the substitution pattern and by choice of the metal ion.
The work focuses on predictive capabilities of fundamental cyclic plasticity and fatigue life models, which can be calibrated using limited amount of experiments as specific ones needed for more advanced models are often absent. The analyses are conducted for the synthetic case of exhaust manifold made from cast iron. The thermal boundary conditions from the forced convection were obtained from the computational fluid dynamics considered as a conjugate heat transfer problem. Two rate-independent and temperature-dependent material models were calibrated for structural analyses. Both were validated with experiments on isothermal and anisothermal levels. Sequential thermal–mechanical finite element simulations were performed. Two fatigue life models were employed. The first was a temperature-dependent strain-based fatigue life criterion calibrated from uniaxial data. The second was a temperature-independent energy-based fatigue life criterion resulting in twice lower life than the strain-based criterion, while none of the plasticity models made a significant difference in that prediction.
As PV enters the terawatt era, reliability, sustainability and low carbon footprint of solar modules are key requirements. The N.I.C.E.TM technology from Apollon Solar is a good candidate for significant improvements in these areas. As the second-generation pilot line is now functional with IEC certification underway, we present a holistic assessment of N.I.C.E.TM technology compared with conventional module technology with encapsulant. This includes electrical performance and cost/consumables, reliability, and degradation mechanisms as well as sustainability aspects. In addition, the new generation of N.I.C.E.-wire modules are presented that use thin round Cu wires instead of flat ribbons for interconnection. This candidate technology for an alternative to the Smart Wire Connection Technology (SWCT) is investigated experimentally as well as via numerical simulations.
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.
Cyclic micro-bending tests on fcc single crystal Ni-base Alloy 718 cantilevers with different crystal orientations were performed to analyze the influence of activated slip systems on dislocation plasticity, latent hardening and the Bauschinger effect. The investigations indicate that plasticity in single crystal micro-cantilevers is significantly influenced by two phenomena - dislocation interaction and dislocation pile-up at the neutral plane. Both phenomena occur at the same time. Their ratio seems to be determined by the activated slip systems. Slip trace analysis indicates that the activation of only one slip system leads to a strong localization of plasticity to a limited number of parallel slip bands. This results in low dislocation interaction and consequently pronounced pile-ups at the neutral plane. In multi slip orientation, the second slip system leads to activation of significantly more dislocation sources, causing a much earlier and more homogeneous elastic-plastic transition zone. In stress-strain hysteresis loops during bending, pronounced dislocation interaction in multi slip orientation leads to a more pronounced latent hardening. The results suggest that on a microstructural length scale, plasticity behavior is strongly affected by activated slip systems, which determine local dislocation phenomena. Based on the results presented in this paper, a finite element analysis of latent hardening and the Bauschinger effect using a single crystal plasticity model with latent kinematic hardening is presented in Part II.
Der prozentuale Energieaufwand für die Warmwasserbereitung ist umso höher, je geringer der Bedarf an Raumwärme – erreicht durch besser gedämmte Gebäudehüllen – ist. Gleichzeitig kann dieser Aufwand für Warmwasser aufgrund der normativ geforderten Systemtemperaturen von 60/55 °C bei zentraler Warmwasserbereitung über Wärmepumpen nur vergleichsweise energieaufwendig abgedeckt werden. Eine Studie des Fraunhofer ISE zeigt, wie groß dieser Temperatur-Effekt im Vergleich unterschiedlicher Trinkwasser-Erwärmungssysteme ist.
Due to higher combustion chamber temperatures and pressures in efficient combustion engines, both the high-cycle and thermomechanical fatigue loads on service life-critical components, such as the cylinder head, are increasing. Material comparisons and analysis of damage behavior are very expensive and time-consuming using component tests. This study therefore develops a test method for cylinder head materials that takes into account the combined loading conditions from the above-mentioned loads and allows realistic temperature transients and gradients on near-component samples. The near-component cylinder head sample represents the failure-critical exhaust valve crosspiece and is tested in a test rig specially designed with the aid of conjugate heat transfer simulations. In the test rig, the sample is subjected to thermal stress by a hot gas burner and to mechanical stress by a high-frequency pulsator. Optical crack detection allows permanent observation of fatigue crack growth and crack closure during the test. Fractographic and metallo-graphic examinations of the fracture areas as well as analyses of the damage patterns show that loads close to engine operation can be set in this way and their influences on the damage can be monitored.
In diesem Beitrag werden die Bereitstellungskosten flexibler Systemkomponenten im deutschen Stromsystem analysiert, zu deren Quantifizierung eine einheitliche Methodik entwickelt wird. Dabei ist das Ziel des Beitrags, zeitlich differenzierte Kostenpotenzialkurven für die Jahre 2015 und 2030 zu erarbeiten, anhand derer die energiespezifischen Kosten der markt- und systemdienlichen Flexibilitätsbereitstellung verglichen und die einzelnen Flexibilitätsoptionen in einen Gesamtkontext eingeordnet werden können.
Der Einsatz flexibler Systemkomponenten wird hierzu in die drei Hauptphasen (1) Vorhaltung, (2) Abruf und (3) Einsatzfolgen unterteilt, woraus sich drei kongruente Kostengruppen ableiten lassen, nach denen die einzelnen Kostenbestandteile identifiziert und als Ergebnis die Bereitstellungskosten quantifiziert werden. Neben fossil-thermischen Kraftwerken werden dabei bspw. die Kraft-Wärme-Kopplung, Biogasanlagen, Pumpspeicher- und Laufwasserkraftwerke sowie steuerbare Lasten untersucht.
Zur anschließenden Abbildung der teils negativen Bereitstellungskosten wird die herkömmliche Darstellungsform der Merit Order entlang der Ordinate um die Abbildung negative Werte erweitert und die Abszisse für die Abbildung negativer Flexibilität in umgekehrter Reihenfolge angeordnet. Das Ergebnis sind zwei zusammenhängende Graphen, mittels derer sich die Bereitstellungskosten verschiedener Flexibilitätsoptionen gegenüberstellen und anschaulich vergleichen lassen.
Durch die Festlegung eines Rahmenszenarios zur Entwicklung des deutschen Stromsystems bis zum Jahr 2030 wird anschließend auch die zukünftige Perspektive der Flexibilitätsbereitstellung in Deutschland analysiert. Aus den Ergebnissen lässt sich ableiten, dass der deutsche Kraftwerkspark mit einem fortschreitenden Rückbau der Kohlekraftwerke nur dann zunehmend flexibler wird und auf höhere Schwankungen im Stromnetz reagieren kann, wenn von einem gleichzeitigen Zubau moderner erdgasbetriebener Kraftwerke ausgegangen wird. In diesem Fall steigen die Bereitstellungskosten positiver Flexibilität, was sich beispielsweise durch zukünftig steigende Brennstoffpreise bergründen lässt. Jedoch kann bspw. durch die Transformation der Kraft-Wärme-Kopplung hin zu einer grundsätzlich stromgeführten Fahrweise zukünftig eine vergleichsweise kostengünstige Flexibilitätsbereitstellung erschlossen und somit auch ein gleichbleibendes oder oftmals sogar höheres Flexibilitätsniveau am Markt erreicht werden.
Pure component sorption isotherms of n-butane, isobutane, 1-butene and isobutene on the metal–organic framework (MOF) 3∞[Cu4(μ4-O)(μ2-OH)2(Me2trz-pba)4] at various temperatures between 283 K and 343 K and pressures up to 300 kPa are presented. The isotherms show a stepwise pore filling which is typical for structurally flexible materials with broad adsorption–desorption hysteresis loops. Gate opening pressures in their endemic characteristic depend on the used hydrocarbon gases. From all investigated gases only the isotherms of 1-butene present a second step at a relative pressure above p/p0 = 0.55. As a consequence, only 1-butene can fully open the framework resulting in a pore volume of 0.54 cm3 g−1. This result is in good agreement with the value of 0.59 cm3 g−1 calculated based on single crystal structure data. The isosteric heat of adsorption was calculated from the experimental isotherms for all C4-isomers. At low loadings the isosteric heat is in a narrow region between 41 and 49 kJ mol−1. Moreover, in situ XRD measurements at different relative hydrocarbon pressures were performed at 298 K for the C4-isomers. The differences in the pressure-depending powder diffraction patterns indicate phase transitions as a result of adsorption. Similar diffraction patterns were observed for all C4-hydrocarbons, except 1-butene, where the second step at higher relative pressure (p/p0 > 0.55) is accompanied by an additional phase transition. This powder pattern resembles that of the as-synthesized MOF material containing solvent molecules in the pore system. The resulting structural changes of the material during guest and pressure induced external stimuli are evidenced by the new coupled XRD adsorption equipment.
An isomorphous series of 10 microporous copper-based metal–organic frameworks (MOFs) with the general formulas ∞3[{Cu3(μ3-OH)(X)}4{Cu2(H2O)2}3(H-R-trz-ia)12] (R = H, CH3, Ph; X2– = SO42–, SeO42–, 2 NO32– (1–8)) and ∞3[{Cu3(μ3-OH)(X)}8{Cu2(H2O)2}6(H-3py-trz-ia)24Cu6]X3 (R = 3py; X2– = SO42–, SeO42– (9, 10)) is presented together with the closely related compounds ∞3[Cu6(μ4-O)(μ3-OH)2(H-Metrz-ia)4][Cu(H2O)6](NO3)2·10H2O (11) and ∞3[Cu2(H-3py-trz-ia)2(H2O)3] (12Cu), which are obtained under similar reaction conditions. The porosity of the series of cubic MOFs with twf-d topology reaches up to 66%. While the diameters of the spherical pores remain unaffected, adsorption measurements show that the pore volume can be fine-tuned by the substituents of the triazolyl isophthalate ligand and choice of the respective copper salt, that is, copper sulfate, selenate, or nitrate.
Synthesis and crystal structure of a novel copper-based MOF material are presented. The tetragonal crystal structure of [ ∞ 3 ( Cu 4 ( μ 4 -O ) ( μ 2 -OH ) 2 ( Me 2 trz p ba ) 4 ] possesses a calculated solvent-accessible pore volume of 57%. Besides the preparation of single crystals, synthesis routes to microcrystalline materials are reported. While PXRD measurements ensure the phase purity of the as-synthesized material, TD-PXRD measurements and coupled DTA–TG–MS analysis confirm the stability of the network up to 230 °C. The pore volume of the microcrystalline material determined by nitrogen adsorption at 77 K depends on the synthetic conditions applied. After synthesis in DMF/H2O/MeOH the pores are blocked for nitrogen, whereas they are accessible for nitrogen after synthesis in H2O/EtOH and subsequent MeOH Soxhleth extraction. The corresponding experimental pore volume was determined by nitrogen adsorption to be V Pore = 0.58 cm 3 g - 1 . In order to characterize the new material and to show its adsorption potential, comprehensive adsorption studies with different adsorptives such as nitrogen, argon, carbon dioxide, methanol and methane at different temperatures were carried out. Unusual adsorption–desorption isotherms with one or two hysteresis loops are found – a remarkable feature of the new flexible MOF material.
The newly synthesized Zn4O-based MOF 3∞[Zn4(μ4-O){(Metrz-pba)2mPh}3]·8 DMF (1·8 DMF) of rare tungsten carbide (acs) topology exhibits a porosity of 43% and remarkably high thermal stability up to 430 °C. Single crystal X-ray structure analyses could be performed using as-synthesized as well as desolvated crystals. Besides the solvothermal synthesis of single crystals a scalable synthesis of microcrystalline material of the MOF is reported. Combined TG-MS and solid state NMR measurements reveal the presence of mobile DMF molecules in the pore system of the framework. Adsorption measurements confirm that the pore structure is fully accessible for nitrogen molecules at 77 K. The adsorptive pore volume of 0.41 cm3 g−1 correlates well with the pore volume of 0.43 cm3 g−1 estimated from the single crystal structure.
The effective executing innovation projects requires multiple estimation of market success of new product features in the early stages of customer-centered innovation process such as strategy formulation, evaluation of ideas and concepts and also at a stage close to the market launch. The attempts to integrate customers for estimation of the market success often result in time-consuming customer interviews or lengthy field research. For this reason, industrial companies usually try to skip customer surveys even if they risk that their innovations will fail to bring the anticipated economic outcomes. In many practical cases, the customer surveys are simply not feasible or too expensive. As a result, the internal assessments within companies are frequently the only resource available in innovation process in the industrial environment. The paper discusses the possibilities of the fast identification of promising innovation opportunities and new product features based on the internal competences of companies. It compares the results of customer surveys with the estimation of internal company-experts and analyses the accuracy and validity of the expert assessments. The presented case studies demonstrate the accuracy rate between 43% and 77% for prediction of new product features with high market potential by company-internal experts. The paper proposes the evaluation methods to increase the accuracy rate and outlines that one of the essential requirements for reliable forecasting by the experts is their profound understanding of the customer working process, the ability to estimate the importance of customer needs and to assess the level of customer satisfaction with current products on the market.
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.
Systemic Constellations are a phenomenological approach to resolving personal, professional and organizational issues. They offer a way of mapping a present reality, working at the source of the hidden dynamics and moving to a resolution. This systemic approach often delivers surprising and unexpected insights while also offering the possibility to analyze and solve organizational problems. Rational analysis provides the whole picture of the problem which often turns out to be too complex for a decision making. Systemic constellations can help to simplify and clarify the situation and inform what has to happen next [8], [17]. The outcomes of systemic constellations as an additional resource for solving comprehensive technical problems have not yet been sufficiently investigated. In structural constellation work dealing with technical problems, the individuals who are involved in the problem situation are used to represent different system components, substances or fields. A moderator voices the feedback from the representatives concerning their feelings or intuitive movements, and points to possible solutions. For example, a moderator places the representatives somewhere in the room, develops a three-dimensional picture of the constellation of the analyzed situation and tries to expose the factors empowering or blocking the way towards constructive solutions [13]. This paper explores the theoretical background and practical outcomes of the systemic constellation method for technical problem solving. It presents some case study work which has been conducted in recent years, and then discusses its findings and implications. The research outlined in this paper demonstrates that the noteworthy contribution of structural constellation work for problem solving is typically the result of a combination of functional analysis and the feeling-as-information principle. The constellation work helps, at first, to reveal the subjective experiences, such as feelings, moods, emotions, and bodily sensations, and then to accept them as a source of objective information relevant to the decision making process. In accordance with the latest research [19], the use of feelings as a source of information follows the same principles as the use of any other information. This paper provides the structures of some standard templates and types of constellation work for technical problems, and discusses the preconditions for their application.
In den letzten Jahren sind verstärkt große Batteriespeichersysteme in der Mittel- und Hochspannungsebene in Deutschland installiert worden. Neben dem Einsatz für lokale Anwendungszwecke wie Eigenverbrauchsmaximierung oder Lastspitzenkappung sind seit 2016 etwa 250 MW aus Batteriespeichern für die Teilnahme am Markt für Primärregelleistung (PRL) präqualifiziert worden. Damit können bereits 40 % des aktuellen Bedarfs der deutschen Übertragungsnetzbetreiber (ÜNB) gedeckt werden. Für einen zuverlässigen Betrieb von Batteriespeichern sind intelligente Betriebsstrategien erforderlich, die im Rahmen dieser Analyse vorgestellt werden.