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In the course of the last few years, our students are becoming increasingly unhappy. Sometimes they stop attending lectures and even seem not to know how to behave correctly. It feels like they are getting on strike. Consequently, drop-out rates are sky-rocketing. The lecturers/professors are not happy either, adopting an “I-don’t-care” attitude.
An interdisciplinary, international team set in to find out: (1) What are the students unhappy about? Why is it becoming so difficult for them to cope? (2) What does the “I-don’t-care” attitude of professors actually mean? What do they care or not care about? (3) How far do the views of the parties correlate? Could some kind of mutual understanding be achieved?
The findings indicate that, at least at our universities, there is rather a long way to go from “Engineering versus Pedagogy” to “Engineering Pedagogy”.
Die gefährliche Wirkung von Kerben auf Konstruktionsteile bei Dauerbeanspruchungen ist dem Konstrukteur bekannt. Trotzdem sind viele in der Praxis beobachteten Schadensbilder an Passverzahnungen fast durchweg auf nicht genügend berücksichtigte Kerbwirkung infolge der konstruktiv bedingten Mehrfachkerben zurückzuführen. Die hohen Anforderungen vor allem an Drehmoment übertragende und hochbeanspruchte Konstruktionsteile zwingen uns, der Frage der Kerbwirkungen sowie Maßnahmen zu deren Milderung erhöhte Aufmerksamkeit zu widmen. Der vorliegende Beitrag beschreibt erste Untersuchungsergebnisse mit der Finite-Elemente-Methode (FEM) zur Ermittlung der Kerbwirkung an den Übergangsstellen für die nach DIN 5480 genormten Passverzahnungen mit freiem Auslauf bei Torsion und Biegung. Die rechnerisch abgeschätzten Form- und Kerbwirkungszahlen an Passverzahnungen werden mit experimentellen Kerbwirkungszahlen aus den Ermüdungsversuchen verglichen. Das Ziel ist es, den Stand der Technik hinsichtlich der Berechnung der Tragfähigkeit und Ermüdungsfestigkeit bei Passverzahnungen weiterzuentwickeln und die neu gewonnenen Form- und Kerbwirkungszahlen in die Berechnungsvorschriften DIN 743 und DIN 5466 einzubinden.
In 4D printing an additively manufactured component is given the ability to change its shape or function under the influence of an external stimulus. To achieve this, special smart materials are used that are able to react to external stimuli in a specific way. So far, a number of different stimuli have already been investigated and initial applications have been impressively demonstrated, such as self-folding bodies and simple grippers. However, a methodical specification for the selection of the stimuli and their implementation was not yet in the foreground of the development.
The focus of this work is therefore to develop a methodical approach with which the technology of 4DP can be used in a solution- and application-oriented manner. The developed approach is based on the conventional design methodology for product development to solve given problems in a structured way. This method is extended by specific approaches under consideration of the 4D printing and smart materials.
To illustrate the developed method, it is implemented in practice using a problem definition in the form of an application example. In this example, which represents the recovery of an object from a difficult-to-access environment, the individual functions of positioning, gripping and extraction are implemented using 4D printing. The material extrusion process is used for additive manufacturing of all components of the example. Finally, the functions are successfully tested. The developed approach offers an innovative and methodical approach to systematically solve technical complex problems using 4DP and smart materials.
One of the challenges in humanoid robotics is motion control. Interacting with humans requires impedance control algorithms, as well as tackling the problem of the closed kinematic chains which occur when both feet touch the ground. However, pure impedance control for totally autonomous robots is difficult to realize, as this algorithm needs very precise sensors for force and speed of the actuated parts, as well as very high sampling rates for the controller input signals. Both requirements lead to a complex and heavy weight design, which makes up for heavy machines unusable in RoboCup Soccer competitions.
A lightweight motor controller was developed that can be used for admittance and impedance control as well as for model predictive control algorithms to further improve the gait of the robot.
There are additional long-term effects which also change the micro-structure of the polymer network and consequently the effective number of polymer chains in the material. These effects are summarized by ageing processes and will be used in the following to explain the basic assumptions of the model which can be generalized to simulate the viscous behaviour of the material. An implementation of these concepts into FEM codes is straightforward and has been carried out to the solver ABAQUS, Baaser & Ziegler (2006), Baaser et al. (2009).
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.
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.
Most recently, the federal government in Germany published new climate goals in order reach climate neutrality by 2045. This paper demonstrates a path to a cost optimal energy supply system for the German power grid until the year 2050. With special regard to regionality, the system is based on yearly myopic optimization with the required energy system transformation measures and the associated system costs. The results point out, that energy storage systems (ESS) are fundamental for renewables integration in order to have a feasible energy transition. Moreover, the investment in storage technologies increased the usage of the solar and wind technologies. Solar energy investments were highly accompanied with the installation of short-term battery storage. Longer-term storage technologies, such as H2, were accompanied with high installations of wind technologies. The results pointed out that hydrogen investments are expected to overrule short-term batteries if their cost continues to decrease sharply. Moreover, with a strong presence of ESS in the energy system, biomass energy is expected to be completely ruled out from the energy mix. With the current emission reduction strategy and without a strong presence of large scale ESS into the system, it is unlikely that the Paris agreement 2° C target by 2050 will be achieved, let alone the 1.5° C.
Additive manufacturing is a rapidly growing manufacturing process for which many new processes and materials are currently being developed. The biggest advantage is that almost any shape can be produced, while conventional manufacturing methods reach their limits. Furthermore, a lot of material is saved because the part is created in layers and only as much material is used as necessary. In contrast, in the case of machining processes, it is not uncommon for more than half of the material to be removed and disposed of. Recently, new additive manufacturing processes have been on the market that enables the manufacturing of components using the FDM process with fiber reinforcement. This opens up new possibilities for optimizing components in terms of their strength and at the same time increasing sustainability by reducing materials consumption and waste. Within the scope of this work, different types of test specimens are to be designed, manufactured and examined. The test specimens are tensile specimens, which are used both for standardized tensile tests and for examining a practical component from automotive engineering used in student project. This project is a vehicle designed to compete in the Shell Eco-marathon, one of the world’s largest energy efficiency competitions. The aim is to design a vehicle that covers a certain distance with as little fuel as possible. Accordingly, it is desirable to manufacture the components with the lowest possible weight, while still ensuring the required rigidity. To achieve this, the use of fiber-reinforced 3D-printed parts is particularly suitable due to the high rigidity. In particular, the joining technology for connecting conventionally and additively manufactured components is developed. As a result, the economic efficiency was assessed, and guidelines for the design of components and joining elements were created. In addition, it could be shown that the additive manufacturing of the component could be implemented faster and more sustainably than the previous conventional manufacturing.
Eine neue Prozessidee zur Auftrennung racemischer Wirkstoffe unter Verwendung nanoskaliger AlO(OH)‐Hohlkugeln als Adsorbens und überkritischen Kohlenstoffdioxides (sc‐CO2) als Lösungsmittel wird vorgestellt. Zur Auslegung des Prozesses werden Untersuchungen zur Abscheidung der racemischen Wirkstoffe (RS)‐Flurbiprofen, (RS)‐Ibuprofen, (RS)‐Ketoprofen und den reinen Enantiomeren (R)‐Flurbiprofen, (S)‐Ibuprofen und (S)‐Ketoprofen an AlO(OH)‐Hohlkugeln präsentiert und bewertet. Zudem werden Adsorptionsdaten von gasförmigem CO2 an den Hohlkugeln und kommerziellen AlO(OH)‐Partikeln, die mit einer Magnetschwebewaage ermittelt wurden, verglichen. Abschließend werden erste Ergebnisse von orientierenden Versuchen zur Adsorption von racemischem Flurbiprofen aus sc‐CO2 an den Hohlkugeln vorgestellt.
Process engineering focuses on the design, operation, control and optimization of chemical, physical and biological processes and has applications in many industries. Process Intensification is the key development approach in the modern process engineering. The proposed Advanced Innovation Design Approach (AIDA) combines the holistic innovation process with the systematic analytical and problem solving tools of the theory of inventive problem solving TRIZ. The present paper conceptualizes the AIDA application in the field of process engineering and especially in combination with the Process Intensification. It defines the AIDA innovation algorithm for process engineering and describes process mapping, problem ranking, and concept design techniques. The approach has been validated in several industrial case studies. The presented research work is a part of the European project “Intensified by Design® platform for the intensification of processes involving solids handling”.
Alexander von Humboldt, a German scientist and explorer of the 19th century, viewed the natural world holistically and described the harmony of nature among the diversity of the physical world as a conjoining between all physical disciplines. He noted in his diary: “Everything is interconnectedness.”
The main feature of Humboldt’s pioneering work was later named “Humboldtian science”, meaning the accurate study of interconnected real phenomena in order to find a definite law and a dynamic cause.
Following Humboldt's idea of nature, an Internet edition of his works must preserve the author’s original intention, retain an awareness of all relevant works, and still adhere to the requirements of scholarly edition.
At the present time, however, the highly unconventional form of his publications has undermined the awareness and a comprehensive study of Humboldt’s works.
Digital libraries should supply dynamic links to sources, maps, images, graphs and relevant texts. New forms of interaction and synthesis between humanistic texts and scientific observation need to be created.
Information technology is the only way to do justice to the broad range of visions, descriptions and the idea of nature of Humboldt’s legacy. It finally leads to virtual research environments as an adequate concept to redesign our digital archives, not only for Humboldt’s documents, but for all interconnected data.
The authors present an abiotically catalyzed glucose fuel cell and demonstrate its application as energy harvesting power source for a cardiac pacemaker. This is enabled by an optimized DC-DC converter operating at 40 % conversion efficiency, which surpasses commercial low-power DC-DC converters. The required fuel cell surface area can thus be reduced from about 125 cm2 to 18 cm2, which would allow for its direct integration onto the pacemaker casing.
Ein tiefgreifendes Verständnis des zyklischen Plastizitätsverhaltens metallischer Werkstoffe ist sowohl für die Optimierung der Materialeigenschaften als auch für die industrielle Auslegung und Fertigung von Bauteilen von hoher Relevanz. Insbesondere moderne Legierungen wie Duplex-Stähle zeigen unter Lastumkehr aufgrund des komplexen mehrphasigen Gefüges sowie der Neigung zu verschiedenen Ausscheidungsreaktionen einen ausgeprägten Bauschinger-Effekt, welcher bei technischen Umformvorgängen berücksichtigt werden muss. Der Bauschinger-Effekt begründet sich maßgeblich in der Entstehung von Rückspannungen, welche aus dem unterschiedlichen Plastizitätsverhalten der austenitischen und ferritischen Phase resultieren. Instrumentierte Mikroindenter-Versuche in ausgewählten Ferrit- und Austenitkörnern haben gezeigt, dass austenitische Gefügebestandteile durch einen deutlich früheren Fließbeginn sowie eine stärkere Rückplastifizierung während der Entlastung charakterisiert sind. Zudem wurde nachgewiesen, dass Ausscheidungen im Rahmen einer 475°C-Versprödung diesen Phasenunterschied verstärken und somit in einem höheren Bauschinger-Effekt resultieren.
Bei thermischen Konvektionsströmungen ist der Einfluß von Geometrie und Randbedingungen für die Strömungsform und den konvektiven Wärmetransport von wesentlicher Bedeutung. Mit Hilfe der optischen Strömungsmeßtechnik (Differentialinterferometrie) wurde die freie Konvektion in einem quaderförmigen Behälter mit seitlicher Beheizung untersucht. Der Aufbau und die Experimente werden beschrieben. Die quantitative Auswertung von Dichte- und Temperaturfeldern aus den Differentialinterferogrammen wird aufgezeigt und der Einfluß unterschiedlicher Randbedingungen wie feste und freie Oberfläche auf die Strömungsform und den Wärmetransport dargelegt. Die eingesetzte Differentialinterferometrie zeigt aufgrund ihrer Anpassungsfähigkeit an die jeweiligen Versuchsbedingungen und durch den einfachen Aufbau spezifische Vorteile gegenüber dem Mach-Zehnder Interferometer.
Today, thermoforming moulds are mostly produced using conventional mould-building technologies (e.g. milling and drilling) and are made of metal (e.g. aluminium or steel) or hardwood. The tools thus produced are very robust, but are only cost-effective in mass production. For the production of small batches of thermoformed parts, there is a need for moulds which can be produced quickly and economically. A new approach which significantly reduces the production time and cost is the 3D printing process (3DP). The use of this technology to produce thermoforming moulds offers many new options in the geometries which can be manufactured, and in manufacturing time and costs. In a case study of a thermoformed part (a scaled automotive model), the pre-processing of the CAD model of a mould is demonstrated. The mould can be printed within a few hours, and is sufficiently heat-resistant for moulding processes. The important advantages of moulds printed in 3D, in comparison to moulds built using conventional technologies, are the ability to create any shape of channels for the vacuum and the simplification in the production of tool mock-ups. This paper also discusses the economics of the technique, such as a comparison of material costs and manufacturing costs in relation to conventional production technologies and materials.
Cast aluminum cylinder blocks are frequently used in gasoline and diesel internal combustion engines because of their light-weight advantage. However, the disadvantage of aluminum alloys is their relatively low strength and fatigue resistance which make aluminum blocks prone to fatigue cracking. Engine blocks must withstand a combination of low-cycle fatigue (LCF) thermal loads and high-cycle fatigue (HCF) combustion and dynamic loads. Reliable computational methods are needed that allow for accurate fatigue assessment of cylinder blocks under this combined loading. In several publications, the mechanism-based thermomechanical fatigue (TMF) damage model DTMF describing the growth of short fatigue cracks has been extended to include the effect of both LCF thermal loads and superimposed HCF loadings. This approach is applied to the finite life fatigue assessment of an aluminum cylinder block. The required material properties related to LCF are determined from uniaxial LCF tests. The additional material properties required for the assessment of superimposed HCF are obtained from the literature for similar materials. The predictions of the model agree well with engine dyno test results. Finally, some improvements to the current process are discussed.
4D printing (4DP) is an evolutionary step of 3D printing, which includes the fourth dimension, in this case the time. In different time steps the printed structure shows different shapes, influenced by external stimuli like light, temperature, pH value, electric or magnetic field. The advantage of 4DP is the solution of technical problems without the need for complex internal energy supply via cables or pipes. Previous approaches to 4D printing with magnetoresponsive materials only use materials with limited usability (e.g. hydrogels) and complex programming during the manufacturing process (e.g. using magnets on the nozzle). The 4D printing using unmagnetized particles and the later magnetization allows the use of a standard 3D printer and has the advantage of being easily reproducible and relatively inexpensive for further application. Therefore, a magnetoresponsive feedstock filament is produced which shows elastic and magnetic properties. In a first step, pellets are produced by compounding polymer with magnetic particles. In a second step, those pellets are extruded in form of filament. This filament is printed using a conventional printing system for Material Extrusion (MEX-TRB/P). Various prototypes have been printed, deformed and magnetized, which is called programming. In comparison to shape memory polymers (SMP) the repeatability of the movement is better. The results show the possibilities of application and function of magnetoresponsive materials. In addition, an understanding of the behaviour of this novel material is achieved.
More than 200 years ago, the scientist Alexander von Humboldt noted in his travel diaries that "everything is interconnectedness", when he was fascinated by nature and the phenomena observed. The view of nature has become much more detailed through the knowledge of phenomena and natural processes, which led to a more precise view of nature shaped by Humboldt. Technological progress and the artificial intelligence of highly developed computer systems are upsetting this view and changing the established world view through a new, unprecedented interaction between man and machinery. Thus we need digital axioms and comprehensive rules and laws for such autonomous acting systems that determine human interaction between cybernetic systems and biological individuals. This digital humanism should encompass our relationship to nature, our handling of the complexity and diversity of nature and the technological influences on society in order to avoid technical colonialism through supercomputers.
To improve the building’s energy efficiency many parameters should be assessed considering the building envelope, energy loads, occupation, and HVAC systems. Fenestration is among the most important variables impacting residential building indoor temperatures. So, it is crucial to use the most optimal energy-efficient window glazing in buildings to reduce energy consumption and at the same time provide visual daylight comfort and thermal comfort. Many studies have focused on the improvement of building energy efficiency focusing on the building envelope or the heating, ventilation, and cooling systems. But just a few studies have focused on studying the effect of glazing on building energy consumption. Thus, this paper aims to study the influence of different glazing types on the building’s heating and cooling energy consumption. A real case study building located under a semi-arid climate was used. The building energy model has been conducted using the OpenStudio simulation engine. Building indoor temperature was calibrated using ASHRAE’s statistical indices. Then a comparative analysis was conducted using seven different types of windows including single, double, and triple glazing filled with air and argon. Tripleglazed and double-glazed windows with argon space offer 37% and 32% of annual energy savings. It should be stressed that the methodology developed in this paper could be useful for further studies to improve building energy efficiency using optimal window glazing.
Der Bericht beschreibt die Vorgehensweise für die Entwicklung von Hochleistungszweitaktmotoren beim Institut für Transportwesen und Motorentechnik (ITM). Die gezielte Auswertung von motorischen Daten bietet die Möglichkeit, Motorenentwicklungsprozesse in wichtigen Fragestellung zu unterstützen. Für die Auslegung von Bauteilen und Prozessen werden Simulationsprogramme eingesetzt. Diese Entwicklungswerkzeuge können effizienter angewandt werden, wenn die Berechnungsergebnisse einer Qualitätskontrolle unterliegen. Wichtig hierfür sind Bewertungskriterien, die aus der Erfahrung einer Vielzahl von Versuchen bestehen. Da in Produktion gegangene Motoren üblicherweise schon einen Evolutionsprozeß durchlaufen haben, kann vermutet werden, daß solche Kriterien von erfolgreichen und weniger erfolgreichen Produkten in der Weise abgeleitet werden können, wie dies hier vorgestellt wurde. Die Angabe von Trendfunktionen für konstruktive Merkmale und Betriebsparameter ist notwendig um eine bedarfsorientierte Vorauslegung von Antrieben durchführen zu können. Alle hier vorgestellten Ergebnisse sind natürlich von der Datenmenge abhängig, die zu den jeweiligen Fragestellungen ausgewertet werden kann. Dazu müssen alle durchgeführten Versuchsreihen in die Datenbank eingeführt und mit Ergebnissen der Simulationsrechnungen in Beziehung gesetzt werden.
Schulgebäude im Liegenschaftsbestand vieler Kommunen treten in den vergangenen Jahren immer stärker ins Interesse der Öffentlichkeit. Viele der Gebäude stammen aus den 70-er oder 80-er Jahren und stehen im Rahmen der Bestandserhaltung für Modernisierungsmaßnahmen an. Insbesondere die hohen Betriebskosten für die Heizung hatten bisher Maßnahmen für den winterlichen Wärmeschutz in den Vordergrund gestellt. Die verstärkt auftretenden sommerlichen Extremtemperaturen an Unterrichtstagen der vergangenen Jahre zeigen zudem einen Handlungsbedarf im Bereich des sommerlichen Wärmeschutzes auf. Für die Aufgaben des Gebäudemanagements und zur Umsetzung eines energieeffizienten Gebäudebetriebs zeigen sich immer stärker die Vorteile einer vielseitig einsetzbaren Gebäudeautomation, die über zentrale Stellen des FM (z.B. Technisches Rathaus) zugänglich ist.
Digital libraries are providing an increasing amount of data, which is normally structured in a classical way by documents and described by metadata as keywords. The data, even in scientific systems such as digital libraries and virtual research environments, will contain a great amount of noise or information unnecessary for our personal interests. Although there has been a lot of progress in the field of information retrieval, search techniques and other content finding methods, there is still much to be done in the field of information retrieval based on user behavior. This paper presents an approach deployed in the Humboldt Digital Library (HDL) to facilitate the retrieval of relevant information to the users of the system, making recommendations of paragraphs based on their profile and the behavior of other users who share similar profiles. The Humboldt digital library represents an innovative system of open access to the legacy of Alexander von Humboldt in a digital form on the Internet (www.avhumboldt.net). It contributes to the key question, how to present interconnected data in a proper form using information technologies.
Do you know that for each banana bunch the complete plant must be cut as well? Only in Brazil 440 million trees are planted annually. With an average weight of 30 kg per banana plant you can estimate about 13,5 million tons of banana residues per year. Although there exist some projects to use these residues for the production of valuable products (e.g fibers for textile and paper production) most of this organic waste material is unused and left for composting on the farmland.
The basic idea of this project is to evaluate this organic waste material for converting it to a renewable and CO2 neutral fuel. Therefore, the different parts of the banana plant (heart, leaves and pseudo stem) were analyzed regarding their biogas potential (specific biogas yield and biogas production kinetics). In further studies the effect of mechanical and enzymatic pretreatments of the different parts of the plants was investigated. This examination could then be the basis for an energetic usage of this organic residue.
The biogas batch experiments were performed according to the german guideline VDI 4630 in 2-L-Batch reactors at 37°C. As biogas substrates, the heart, the leaves and the pseudo stem of the banana plant residue with and without enzymatic/mechanical pretreatment were used.
The different parts of the banana plants result in a specific biogas production yield in the range of 260-470 norm liters per kg organic dry mass.
To determine the influence of the mechanical pretreatment (particle size 1-15 mm) on the biogas production kinetics, the kinetic constants were defined and calculated. The reduction of the particle size leads to an improved biogas production kinetics. Therefore experiments will demonstrate, if the results from the batch experiments can be converted in the continuous fed biogas reactor. The experiments of the enzymatic pretreatment are still under investigation.
Biological in situ methanation: Gassing concept and feeding strategy for enhanced performance
(2017)
The expansion of fluctuating renewable electricity production from wind and solar energy requires huge storage capacities. Power-to-gas (PtG) can contribute to tackle that issue via a two-step process, the electrolytic production of hydrogen and a subsequent methanation step (with additional CO2). The resulting fully grid compatible methane, also known as synthetic natural gas (SNG), can be both stored and transported in the vast existing natural gas infrastructure.
To overcome current major drawbacks of PtG, the relatively low efficiency and the high costs, we developed an improved method for the methanation step. In our approach we use a further development of the biological in situ methanation of hydrogen in biogas plants. Because this strategy uses directly internal residual CO2 from the biogas process in the biogas plant, you neither need additional external CO2 nor special reactors. Thus, PtG is combined with the production of an upgraded highly methane rich raw biogas.
However, the low solubility of hydrogen in aqueous solutions and the exploitation of the maximum biological production rates are still an engineering challenge for high performance biological in situ methanation.
In our experiments a setup with membrane gassing turned out to be most promising to ensure a sufficient gas liquid mass transfer of the hydrogen. The monitoring of hydrogenotrophic and aceticlastic archaea showed some adaption of these microbial subgroups to the hydrogen feed.
In order to achieve high methane concentrations of more than 90 % in the raw biogas a CO2-controlled hydrogen feed flow rate is suggested. For methane concentrations lower than 90 % simple current controlled hydrogen supply can be applied.
Vorgestellt wird ein Konzept zur biologischen Methanisierung von Wasserstoff direkt in Biogasreaktoren, mit dem durch Membranbegasung der Methangehalt des Biogases auf > 96 % erhöht werden kann. Essentiell zum Erreichen solch hoher Methanwerte sind die Einhaltung eines optimalen pH-Bereichs und die Vermeidung von H2-Akkumulation. Im Falle einer Limitierung der Methanbildungsrate durch den eigentlichen anaeroben Abbauprozess der Biomasse ist auch eine externe Zufuhr von CO2 zur weiteren Methanbildung denkbar. Das Verfahren soll weiter optimiert und in einem von der Deutschen Bundesstiftung Umwelt geförderten Projekt in der Biogasanlage einer regionalen Käserei in der Praxis getestet werden. Die hier angestrebte Kombination aus dezentraler Abfallverwertung und Eigenenergieerzeugung eines lebensmittelverarbeitenden Betriebs unter Einbindung in ein intelligentes Erneuerbare Energien - Konzept soll einen zusätzlichen Mehrwert liefern.
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.
The variable refrigerant flow system is one of the best heating, ventilation, and air conditioning systems (HVAC) thanks to its ability to provide thermal comfort inside buildings. But, at the same time, these systems are considered one of the most energy-consuming systems in the building sector. Thus, it is crucial to well size the system according to the building’s cooling and heating needs and the indoor temperature fluctuations. Although many researchers have studied the optimization of the building energy performance considering heating or cooling needs, using air handling units, radiant floor heating, and direct expansion valves, few studies have considered the use of multi-objective optimization using only the thermostat setpoints of VRF systems for both cooling and heating needs. Thus, the main aim of this study is to conduct a sensitivity analysis and a multi-objective optimization strategy for a residential building containing a variable refrigerant flow system, to evaluate the effect of the building performance on energy consumption and improve the building energy efficiency. The numerical model was based on the EnergyPlus, jEPlus, and jEPlus+EA simulation engines. The approach used in this paper has allowed us to reach significant quantitative energy saving by varying the cooling and heating setpoints and scheduling scenarios. It should be stressed that this approach could be applied to several HVAC systems to reduce energy-building consumption.
This study aimed to compare a simplified calculation of the knee abduction moment with the traditional inverse dynamics calculation when athletes perform fake-cut maneuvers with different complexities. In the simplified calculation, we multiply the force vector with its lever arm to the knee, projected onto the local coordinate system of the proximal thigh, hence neglecting the inertial contributions from distal segments. We found very strong ranking consistency using Spearman’s rank correlation coefficient when using the simplified method compared to the traditional calculation. Independent of the tasks, the simplified method resulted in higher moments than the inverse dynamics. This was caused by ignoring the moment caused by segment linear acceleration generating a counteracting moment by about 7%. An alternative to the complex calculations of inverse dynamics can be used to investigate the contributions of the GRF magnitude and its lever arm to the knee.
Eco-innovations in chemical processes should be designed to use raw materials, energy and water as efficiently and economically as possible to avoid the generation of hazardous waste and to conserve raw material reserves. Applying inventive principles identified in natural systems to chemical process design can help avoid secondary problems. However, the selection of nature-inspired principles to improve technological or environmental problems is very time-consuming. In addition, it is necessary to match the strongest principles with the problems to be solved. Therefore, the research paper proposes a classification and assignment of nature-inspired inventive principles to eco-parameters, eco-engineering contradictions and eco-innovation domains, taking into account environmental, technological and economic requirements. This classification will help to identify suitable principles quickly and also to realize rapid innovation. In addition, to validate the proposed classification approach, the study is illustrated with the application of nature-inspired invention principles for the development of a sustainable process design for the extraction of high-purity silicon dioxide from pyrophyllite ores. Finally, the paper defines a future research agenda in the field of nature-inspired eco-engineering in the context of AI-assisted invention and innovation.
Classification of TRIZ Inventive Principles and Sub-Principles for Process Engineering Problems
(2019)
The paper proposes a classification approach of 40 Inventive Principles with an extended set of 160 sub-principles for process engineering, based on a thorough analysis of 155 process intensification technologies, 200 patent documents, 6 industrial case studies applying TRIZ, and other sources. The authors define problem-specific sub-principles groups as a more precise and productive ideation technique, adaptable for a large diversity of problem situations, and finally, examine the anticipated variety of ideation using 160 sub-principles with the help of MATCEM-IBD fields.
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.
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.
The energy system is changing since some years in order to achieve the climate goals from the Paris Agreement which wants to prevent an increase of the global temperature above 2 °C [1]. Decarbonisation of the energy system has become for governments a big challenge and different strategies are being stablished. Germany has set greenhouse gas reduction limits for different years and keeps track of the improvement made yearly. The expansion of renewable energy systems (RES) together with decarbonisation technologies are a key factor to accomplish this objective.
This research is done to analyse the effect of introducing biochar, a decarbonisation technology, and study how it will affect the energy system. Pyrolysis is the process from which biochar is obtained and it is modelled in an open-source energy system model. A sensibility analysis is done in order to assess the effect of changing the biomass potential and the costs for pyrolysis.
The role of pyrolysis is analysed in the form of different future scenarios for the year 2045 to evaluate the impact when the CO2 emission limit is zero. All scenarios are compared to the reference scenario, where pyrolysis is not considered.
Results show that biochar can be used to compensate the emissions from other conventional power plant and achieve an energy transition with lower costs. Furthermore, it was also found that pyrolysis can also reduce the need of flexibility. This study also shows that the biomass potential and the pyrolysis costs can strongly affect the behaviour of pyrolysis in the energy system.
Für die Zahnwellenprofile nach DIN 5480 ist es schwierig, das polare Trägheitsmoment des geschwächten Querschnitts aus der Geometrie festzulegen. Dieses ist jedoch zur Berechnung der Nennspannung oder der Verdrehsteifigkeit erforderlich. Unterschiedliche Nennspannungsdefinitionen stehen dem Konstrukteur zur Verfügung. Diese können z.B. bei der Formzahldarstellung zu Missverständnissen führen. In der Praxis hilft man sich in der Weise, dass man dem durch die Formelemente (Keile, Zähne) geschwächten Querschnitt einen Kreis einbeschreibt und die Spannung einer Ersatzwelle mit dem Durchmesser dh1 dieses einbeschriebenen Kreises ermittelt. Die in der DIN 5466 vorhandene Näherungsgleichung zur Berechnung des Ersatzdurchmessers dh1 verzahnter Wellen geht auf Arbeiten von Nakazawa im Jahr 1951 [Nakazawa, Hajime: On the Torsion of the Spline Shafts. The Japan Society of Mechanical Engineers, 1951, S. 651-658 + S. 643-650, Tokyo Torizo Univers. 1951] und später auf [Schöpf, H.-J.: Festigkeitsuntersuchung an Zahnwellen-Verbindungen mit Spannungsoptik und Dauerschwingversuchen. Dissertation der TU München 1976] zurück. Mit diesem imaginären Durchmesser dh1 kann man das polare Flächenträgheitsmoment und Widerstandsmoment ermitteln. Die Ergebnisgenauigkeit dieser Näherungslösung ist für eine treffsichere Festigkeitsberechnung aus heutiger Sicht unbefriedigend. Ziel dieses Aufsatzes ist es, dem Anwender Möglichkeiten und Ergebnisse zur Verfügung zu stellen, die es ihm gestatten, das effektiv wirkende Widerstandsmoment für verzahnte Wellenprofile genauer zu bestimmen. Dabei wird der dafür notwendige Ersatzdurchmesser mit Hilfe von theoretischen Überlegungen und Programmtools (CAD, Matlab und Excel) für den gesamten nach DIN 5480 festgelegten Geometriebereich unter die Lupe genommen.
For the RoboCup Soccer AdultSize League the humanoid robot Sweaty uses a single fully convolutional neural network to detect and localize the ball, opponents and other features on the field of play. This neural network can be trained from scratch in a few hours and is able to perform in real-time within the constraints of computational resources available on the robot. The time it takes to precess an image is approximately 11 ms. Balls and goal posts are recalled in 99 % of all cases (94.5 % for all objects) accompanied by a false detection rate of 1.2 % (5.2 % for all). The object detection and localization helped Sweaty to become finalist for the RoboCup 2017 in Nagoya.