TY - CHAP A1 - Schartner, Karl-Heinz A1 - Loeb, H. W. A1 - Dachwald, Bernd A1 - Ohndorf, Andreas T1 - Perspectives of electric propulsion for outer planetary and deep space missions T2 - European Planetary Science Congress 2009 N2 - Solar-electric propulsion (SEP) is superior with respect to payload capacity, flight time and flexible launch window to the conventional interplanetary transfer method using chemical propulsion combined with gravity assists. This fact results from the large exhaust velocities of electric low–thrust propulsion and is favourable also for missions to the giant planets, Kuiper-belt objects and even for a heliopause probe (IHP) as shown in three studies by the authors funded by DLR. They dealt with a lander for Europa and a sample return mission from a mainbelt asteroid [1], with the TANDEM mission [2]; the third recent one investigates electric propulsion for the transfer to the edge of the solar system. All studies are based on triple-junction solar arrays, on rf-ion thrusters of the qualified RIT-22 type and they use the intelligent trajectory optimization program InTrance [3]. Y1 - 2009 N1 - European Planetary Science Congress 2009, 13-18 September, Potsdam, Germany SP - 416 EP - 416 ER - TY - JOUR A1 - Richter, Charlotte A1 - Braunstein, Bjoern A1 - Staeudle, Benjamin A1 - Attias, Julia A1 - Suess, Alexander A1 - Weber, Tobias A1 - Mileva, Katya N. A1 - Rittweger, Joern A1 - Green, David A. A1 - Albracht, Kirsten T1 - Contractile behavior of the gastrocnemius medialis muscle during running in simulated hypogravity JF - npj Microgravity N2 - Vigorous exercise countermeasures in microgravity can largely attenuate muscular degeneration, albeit the extent of applied loading is key for the extent of muscle wasting. Running on the International Space Station is usually performed with maximum loads of 70% body weight (0.7 g). However, it has not been investigated how the reduced musculoskeletal loading affects muscle and series elastic element dynamics, and thereby force and power generation. Therefore, this study examined the effects of running on the vertical treadmill facility, a ground-based analog, at simulated 0.7 g on gastrocnemius medialis contractile behavior. The results reveal that fascicle−series elastic element behavior differs between simulated hypogravity and 1 g running. Whilst shorter peak series elastic element lengths at simulated 0.7 g appear to be the result of lower muscular and gravitational forces acting on it, increased fascicle lengths and decreased velocities could not be anticipated, but may inform the development of optimized running training in hypogravity. However, whether the alterations in contractile behavior precipitate musculoskeletal degeneration warrants further study. Y1 - 2021 U6 - http://dx.doi.org/10.1038/s41526-021-00155-7 SN - 2373-8065 N1 - Corresponding author: Charlotte Richter VL - 7 IS - Article number: 32 PB - Springer Nature CY - New York ER - TY - JOUR A1 - Jablonski, Melanie A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Wege, Christina A1 - Schöning, Michael Josef T1 - Detection of plant virus particles with a capacitive field-effect sensor JF - Analytical and Bioanalytical Chemistry N2 - Plant viruses are major contributors to crop losses and induce high economic costs worldwide. For reliable, on-site and early detection of plant viral diseases, portable biosensors are of great interest. In this study, a field-effect SiO2-gate electrolyte-insulator-semiconductor (EIS) sensor was utilized for the label-free electrostatic detection of tobacco mosaic virus (TMV) particles as a model plant pathogen. The capacitive EIS sensor has been characterized regarding its TMV sensitivity by means of constant-capacitance method. The EIS sensor was able to detect biotinylated TMV particles from a solution with a TMV concentration as low as 0.025 nM. A good correlation between the registered EIS sensor signal and the density of adsorbed TMV particles assessed from scanning electron microscopy images of the SiO2-gate chip surface was observed. Additionally, the isoelectric point of the biotinylated TMV particles was determined via zeta potential measurements and the influence of ionic strength of the measurement solution on the TMV-modified EIS sensor signal has been studied. KW - Plant virus KW - Capacitive field-effect sensor KW - Tobacco mosaic virus (TMV) KW - Label-free detection KW - Zeta potential Y1 - 2021 U6 - http://dx.doi.org/10.1007/s00216-021-03448-8 SN - 1618-2650 N1 - Corresponding authors: Arshak Poghossian & Michael J. Schöning VL - 413 SP - 5669 EP - 5678 PB - Springer Nature CY - Cham ER - TY - CHAP A1 - Borggräfe, Andreas A1 - Dachwald, Bernd T1 - Mission performance evaluation for solar sails using a refined SRP force model with variable optical coefficients T2 - 2nd International Symposium on Solar Sailing N2 - Solar sails provide ignificant advantages over other low-thrust propulsion systems because they produce thrust by the momentum exchange from solar radiation pressure (SRP) and thus do not consume any propellant.The force exerted on a very thin sail foil basically depends on the light incidence angle. Several analytical SRP force models that describe the SRP force acting on the sail have been established since the 1970s. All the widely used models use constant optical force coefficients of the reflecting sail material. In 2006,MENGALI et al. proposed a refined SRP force model that takes into account the dependancy of the force coefficients on the light incident angle,the sail’s distance from the sun (and thus the sail emperature) and the surface roughness of the sail material [1]. In this paper, the refined SRP force model is compared to the previous ones in order to identify the potential impact of the new model on the predicted capabilities of solar sails in performing low-cost interplanetary space missions. All force models have been implemented within InTrance, a global low-thrust trajectory optimization software utilizing evolutionary neurocontrol [2]. Two interplanetary rendezvous missions, to Mercury and the near-Earth asteroid 1996FG3, are investigated. Two solar sail performances in terms of characteristic acceleration are examined for both scenarios, 0.2 mm/s2 and 0.5 mm/s2, termed “low” and “medium” sail performance. In case of the refined SRP model, three different values of surface roughness are chosen, h = 0 nm, 10 nm and 25 nm. The results show that the refined SRP force model yields shorter transfer times than the standard model. Y1 - 2010 N1 - 2nd International Symposium on Solar Sailing, ISSS 2010, 2010-07-20 - 2010-07-22. New York City College of Technology of the City University of New York, USA SP - 1 EP - 6 ER - TY - CHAP A1 - Ohndorf, Andreas A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang A1 - Schartner, Karl-Heinz T1 - Flight times to the heliopause using a combination of solar and radioisotope electric propulsion T2 - 32nd International Electric Propulsion Conference N2 - We investigate the interplanetary flight of a low-thrust space probe to the heliopause,located at a distance of about 200 AU from the Sun. Our goal was to reach this distance within the 25 years postulated by ESA for such a mission (which is less ambitious than the 15-year goal set by NASA). Contrary to solar sail concepts and combinations of allistic and electrically propelled flight legs, we have investigated whether the set flight time limit could also be kept with a combination of solar-electric propulsion and a second, RTG-powered upper stage. The used ion engine type was the RIT-22 for the first stage and the RIT-10 for the second stage. Trajectory optimization was carried out with the low-thrust optimization program InTrance, which implements the method of Evolutionary Neurocontrol,using Artificial Neural Networks for spacecraft steering and Evolutionary Algorithms to optimize the Neural Networks’ parameter set. Based on a parameter space study, in which the number of thrust units, the unit’s specific impulse, and the relative size of the solar power generator were varied, we have chosen one configuration as reference. The transfer time of this reference configuration was 29.6 years and the fastest one, which is technically more challenging, still required 28.3 years. As all flight times of this parameter study were longer than 25 years, we further shortened the transfer time by applying a launcher-provided hyperbolic excess energy up to 49 km2/s2. The resulting minimal flight time for the reference configuration was then 27.8 years. The following, more precise optimization to a launch with the European Ariane 5 ECA rocket reduced the transfer time to 27.5 years. This is the fastest mission design of our study that is flexible enough to allow a launch every year. The inclusion of a fly-by at Jupiter finally resulted in a flight time of 23.8 years,which is below the set transfer-time limit. However, compared to the 27.5-year transfer,this mission design has a significantly reduced launch window and mission flexibility if the escape direction is restricted to the heliosphere’s “nose". KW - low-thrust trajectory optimization KW - heliosphere KW - ion propulsion Y1 - 2011 N1 - IEPC-2011-051 32nd International Electric Propulsion Conference,September 11–15, 2011 Wiesbaden, Germany SP - 1 EP - 12 ER - TY - CHAP A1 - Schmidt, Thomas A1 - Kasch, Susanne A1 - Eichler, Fabian A1 - Thurn, Laura T1 - Process strategies on laser-based melting of glass powder T2 - Lasers in Manufacturing Conference 2021 N2 - This paper presents the laser-based powder bed fusion (L-PBF) using various glass powders (borosilicate and quartz glass). Compared to metals, these require adapted process strategies. First, the glass powders were characterized with regard to their material properties and their processability in the powder bed. This was followed by investigations of the melting behavior of the glass powders with different laser wavelengths (10.6 µm, 1070 nm). In particular, the experimental setup of a CO2 laser was adapted for the processing of glass powder. An experimental setup with integrated coaxial temperature measurement/control and an inductively heatable build platform was created. This allowed the L-PBF process to be carried out at the transformation temperature of the glasses. Furthermore, the component’s material quality was analyzed on three-dimensional test specimen with regard to porosity, roughness, density and geometrical accuracy in order to evaluate the developed L-PBF parameters and to open up possible applications. KW - 3D-printing KW - glass KW - additive manufactureing KW - laser based powder fusion Y1 - 2021 ER - TY - JOUR A1 - Loeb, Horst Wolfgang A1 - Schartner, Karl-Heinz A1 - Dachwald, Bernd A1 - Ohndorf, Andreas A1 - Seboldt, Wolfgang T1 - Interstellar heliopause probe JF - Труды МАИ N2 - There is common agreement within the scientific community that in order to understand our local galactic environment it will be necessary to send a spacecraft into the region beyond the solar wind termination shock. Considering distances of 200 AU for a new mission, one needs a spacecraft traveling at a speed of close to 10 AU/yr in order to keep the mission duration in the range of less than 25 yrs, a transfer time postulated by European Space Agency (ESA). Two propulsion options for the mission have been proposed and discussed so far: the solar sail propulsion and the ballistic/radioisotope-electric propulsion (REP). As a further alternative, we here investigate a combination of solar-electric propulsion (SEP) and REP. The SEP stage consists of six 22-cms diameter RIT-22 ion thrusters working with a high specific impulse of 7377 s corresponding to a positive grid voltage of 5 kV. Solar power of 53 kW at begin of mission (BOM) is provided by a lightweight solar array. Y1 - 2012 IS - 60 SP - 2 EP - 2 PB - Moskauer Staatliches Luftfahrtinstitut (МАИ) CY - Moskau ER - TY - JOUR A1 - Welden, Rene A1 - Nagamine Komesu, Cindy A. A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef A1 - Wagner, Torsten T1 - Photoelectrochemical enzymatic penicillin biosensor: A proof-of-concept experiment JF - Electrochemical Science Advances N2 - Photoelectrochemical (PEC) biosensors are a rather novel type of biosensors thatutilizelighttoprovideinformationaboutthecompositionofananalyte,enablinglight-controlled multi-analyte measurements. For enzymatic PEC biosensors,amperometric detection principles are already known in the literature. In con-trast, there is only a little information on H+-ion sensitive PEC biosensors. Inthis work, we demonstrate the detection of H+ions emerged by H+-generatingenzymes, exemplarily demonstrated with penicillinase as a model enzyme on atitanium dioxide photoanode. First, we describe the pH sensitivity of the sensorand study possible photoelectrocatalytic reactions with penicillin. Second, weshow the enzymatic PEC detection of penicillin. KW - enzymatic biosensor KW - penicillin KW - penicillinase KW - photoelectrochemistry KW - titanium dioxide photoanode Y1 - 2021 U6 - http://dx.doi.org/10.1002/elsa.202100131 SN - 2698-5977 N1 - Corresponding auhtor: Michael J. Schöning VL - 2 IS - 4 SP - 1 EP - 5 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Oliveira, Danilo A. A1 - Molinnus, Denise A1 - Beging, Stefan A1 - Siqueira Jr, José R. A1 - Schöning, Michael Josef T1 - Biosensor Based on Self-Assembled Films of Graphene Oxide and Polyaniline Using a Field-Effect Device Platform JF - physica status solidi (a) applications and materials science N2 - A new functionalization method to modify capacitive electrolyte–insulator–semiconductor (EIS) structures with nanofilms is presented. Layers of polyallylamine hydrochloride (PAH) and graphene oxide (GO) with the compound polyaniline:poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PANI:PAAMPSA) are deposited onto a p-Si/SiO2 chip using the layer-by-layer technique (LbL). Two different enzymes (urease and penicillinase) are separately immobilized on top of a five-bilayer stack of the PAH:GO/PANI:PAAMPSA-modified EIS chip, forming a biosensor for detection of urea and penicillin, respectively. Electrochemical characterization is performed by constant capacitance (ConCap) measurements, and the film morphology is characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). An increase in the average sensitivity of the modified biosensors (EIS–nanofilm–enzyme) of around 15% is found in relation to sensors, only carrying the enzyme but without the nanofilm (EIS–enzyme). In this sense, the nanofilm acts as a stable bioreceptor onto the EIS chip improving the output signal in terms of sensitivity and stability. KW - capacitive electrolyte–insulator–semiconductor sensors KW - graphene oxide KW - layer-by-layer technique KW - nanomaterials KW - polyaniline Y1 - 2021 U6 - http://dx.doi.org/10.1002/pssa.202000747 SN - 1862-6319 N1 - Corresponding author: José R. Siqueira Jr & Michael J. Schöning VL - 218 IS - 13 SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Molinnus, Denise A1 - Iken, Heiko A1 - Johnen, Anna Lynn A1 - Richstein, Benjamin A1 - Hellmich, Lena A1 - Poghossian, Arshak A1 - Knoch, Joachim A1 - Schöning, Michael Josef T1 - Miniaturized pH-Sensitive Field-Effect Capacitors with Ultrathin Ta₂O₅ Films Prepared by Atomic Layer Deposition JF - physica status solidi (a) applications and materials science N2 - Miniaturized electrolyte–insulator–semiconductor capacitors (EISCAPs) with ultrathin gate insulators have been studied in terms of their pH-sensitive sensor characteristics: three different EISCAP systems consisting of Al–p-Si–Ta2O5(5 nm), Al–p-Si–Si3N4(1 or 2 nm)–Ta2O5 (5 nm), and Al–p-Si–SiO2(3.6 nm)–Ta2O5(5 nm) layer structures are characterized in buffer solution with different pH values by means of capacitance–voltage and constant capacitance method. The SiO2 and Si3N4 gate insulators are deposited by rapid thermal oxidation and rapid thermal nitridation, respectively, whereas the Ta2O5 film is prepared by atomic layer deposition. All EISCAP systems have a clear pH response, favoring the stacked gate insulators SiO2–Ta2O5 when considering the overall sensor characteristics, while the Si3N4(1 nm)–Ta2O5 stack delivers the largest accumulation capacitance (due to the lower equivalent oxide thickness) and a higher steepness in the slope of the capacitance–voltage curve among the studied stacked gate insulator systems. KW - atomic layer deposition KW - capacitive field-effect sensors KW - pH sensors KW - ultrathin gate insulators Y1 - 2022 U6 - http://dx.doi.org/10.1002/pssa.202100660 SN - 1862-6319 VL - 219 IS - 8 PB - Wiley-VCH CY - Weinheim ER - TY - CHAP A1 - Akimbekov, Nuraly S. A1 - Digel, Ilya A1 - Sherelkhan, Dinara K. A1 - Razzaque, Mohammed S. T1 - Vitamin D and Phosphate Interactions in Health and Disease T2 - Phosphate Metabolism N2 - Vitamin D plays an essential role in calcium and inorganic phosphate (Pi) homeostasis, maintaining their optimal levels to assure adequate bone mineralization. Vitamin D, as calcitriol (1,25(OH)2D), not only increases intestinal calcium and phosphate absorption but also facilitates their renal reabsorption, leading to elevated serum calcium and phosphate levels. The interaction of 1,25(OH)2D with its receptor (VDR) increases the efficiency of intestinal absorption of calcium to 30–40% and phosphate to nearly 80%. Serum phosphate levels can also influence 1,25 (OH)2D and fibroblast growth factor 23 (FGF23) levels, i.e., higher phosphate concentrations suppress vitamin D activation and stimulate parathyroid hormone (PTH) release, while a high FGF23 serum level leads to reduced vitamin D synthesis. In the vitamin D-deficient state, the intestinal calcium absorption decreases and the secretion of PTH increases, which in turn causes the stimulation of 1,25(OH)2D production, resulting in excessive urinary phosphate loss. Maintenance of phosphate homeostasis is essential as hyperphosphatemia is a risk factor of cardiovascular calcification, chronic kidney diseases (CKD), and premature aging, while hypophosphatemia is usually associated with rickets and osteomalacia. This chapter elaborates on the possible interactions between vitamin D and phosphate in health and disease. KW - Vitamin D KW - PTH KW - Phosphate KW - FGF23 KW - Klotho Y1 - 2022 SN - 978-3-030-91621-3 U6 - http://dx.doi.org/10.1007/978-3-030-91623-7_5 SP - 37 EP - 46 PB - Springer CY - Cham ER - TY - JOUR A1 - Pfaff, Raphael A1 - Enning, Manfred A1 - Sutter, Stefan T1 - A risk‑based approach to automatic brake tests for rail freight service: incident analysis and realisation concept JF - SN Applied Sciences N2 - This study reviews the practice of brake tests in freight railways, which is time consuming and not suitable to detect certain failure types. Public incident reports are analysed to derive a reasonable brake test hardware and communication architecture, which aims to provide automatic brake tests at lower cost than current solutions. The proposed solutions relies exclusively on brake pipe and brake cylinder pressure sensors, a brake release position switch as well as radio communication via standard protocols. The approach is embedded in the Wagon 4.0 concept, which is a holistic approach to a smart freight wagon. The reduction of manual processes yields a strong incentive due to high savings in manual labour and increased productivity. KW - Freight rail KW - Brake test KW - Incident analysis KW - Train composition KW - Brake set-up Y1 - 2022 U6 - http://dx.doi.org/10.1007/s42452-022-05007-x SN - 2523-3971 N1 - Corresponding author: Raphael Pfaff VL - 4 IS - 4 SP - 1 EP - 14 PB - Springer CY - Cham ER - TY - CHAP A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang A1 - Häusler, Bernd T1 - Performance requirements for near-term interplanetary solar sailcraft missions T2 - 6th International AAAF Symposium on Space Propulsion: Propulsion for Space Transportation of the XXIst Century N2 - Solar sailcraft provide a wide range of opportunities for high-energy low-cost missions. To date, most mission studies require a rather demanding performance that will not be realized by solar sailcraft of the first generation. However, even with solar sailcraft of moderate performance, scientifically relevant missions are feasible. This is demonstrated with a Near Earth Asteroid sample return mission and various planetary rendezvous missions. Y1 - 2002 N1 - 6th International AAAF Symposium on Space Propulsion: Propulsion for Space Transportation of the XXIst Century, Versailles, France, 14-16 May 2002 ER - TY - CHAP A1 - Seboldt, Wolfgang A1 - Dachwald, Bernd T1 - Solar sails for near-term advanced scientific deep space missions T2 - Proceedings of the 8th International Workshop on Combustion and Propulsion N2 - Solar sails are propelled in space by reflecting solar photons off large mirroring surfaces, thereby transforming the momentum of the photons into a propulsive force. This innovative concept for low-thrust space propulsion works without any propellant and thus provides a wide range of opportunities for highenergy low-cost missions. Offering an efficient way of propulsion, solar sailcraft could close a gap in transportation options for highly demanding exploration missions within our solar system and even beyond. On December 17th, 1999, a significant step was made towards the realization of this technology: a lightweight solar sail structure with an area of 20 m × 20 m was successfully deployed on ground in a large facility at the German Aerospace Center (DLR) at Cologne. The deployment from a package of 60 cm × 60 cm × 65 cm with a total mass of less than 35 kg was achieved using four extremely light-weight carbon fiber reinforced plastics (CFRP) booms with a specific mass of 100 g/m. The paper briefly reviews the basic principles of solar sails as well as the technical concept and its realization in the ground demonstration experiment, performed in close cooperation between DLR and ESA. Next possible steps are outlined. They could comprise the in-orbit demonstration of the sail deployment on the upper stage of a low-cost rocket and the verification of the propulsion concept by an autonomous and free flying solar sail in the frame of a scientific mission. It is expected that the present design could be extended to sail sizes of about (40 m)2 up to even (70 m)2 without significant mass penalty. With these areas, the maximum achievable thrust at 1 AU would range between 10 and 40 mN – comparable to some electric thrusters. Such prototype sails with a mass between 50 and 150 kg plus a micro-spacecraft of 50 to 250 kg would have a maximum acceleration in the order of 0.1 mm/s2 at 1 AU, corresponding to a maximum ∆V-capability of about 3 km/s per year. Two near/medium-term mission examples to a near-Earth asteroid (NEA) will be discussed: a rendezvous mission and a sample return mission. KW - solar sail KW - low-thrust KW - near-Earth asteroid KW - sample return KW - solar system Y1 - 2003 N1 - Proceedings of the 8th International Workshop on Combustion and Propulsion. Pozzuoli, Italy, 16 - 21 June 2002. ER - TY - CHAP A1 - Dachwald, Bernd T1 - Solar sail dynamics and control T2 - Encyclopedia of Aerospace Engineering N2 - Solar sails are large and lightweight reflective structures that are propelled by solar radiation pressure. This chapter covers their orbital and attitude dynamics and control. First, the advantages and limitations of solar sails are discussed and their history and development status is outlined. Because the dynamics of solar sails is governed by the (thermo-)optical properties of the sail film, the basic solar radiation pressure force models have to be described and compared before parameters to measure solar sail performance can be defined. The next part covers the orbital dynamics of solar sails for heliocentric motion, planetocentric motion, and motion at Lagrangian equilibrium points. Afterwards, some advanced solar radiation pressure force models are described, which allow to quantify the thrust force on solar sails of arbitrary shape, the effects of temperature, of light incidence angle, of surface roughness, and the effects of optical degradation of the sail film in the space environment. The orbital motion of a solar sail is strongly coupled to its rotational motion, so that the attitude control of these soft and flexible structures is very challenging, especially for planetocentric orbits that require fast attitude maneuvers. Finally, some potential attitude control methods are sketched and selection criteria are given. KW - solar sail KW - sailcraft KW - orbital dynamics KW - orbit control KW - attitude dynamics Y1 - 2010 U6 - http://dx.doi.org/10.1002/9780470686652.eae292 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. A1 - Erpicum, Sebastien A1 - Peltier, Yann A1 - Dewals, Benjamin T1 - Unsteady shallow meandering flows in rectangular reservoirs: a modal analysis of URANS modelling JF - Journal of Hydro-environment Research N2 - Shallow flows are common in natural and human-made environments. Even for simple rectangular shallow reservoirs, recent laboratory experiments show that the developing flow fields are particularly complex, involving large-scale turbulent structures. For specific combinations of reservoir size and hydraulic conditions, a meandering jet can be observed. While some aspects of this pseudo-2D flow pattern can be reproduced using a 2D numerical model, new 3D simulations, based on the unsteady Reynolds-Averaged Navier-Stokes equations, show consistent advantages as presented herein. A Proper Orthogonal Decomposition was used to characterize the four most energetic modes of the meandering jet at the free surface level, allowing comparison against experimental data and 2D (depth-averaged) numerical results. Three different isotropic eddy viscosity models (RNG k-ε, k-ε, k-ω) were tested. The 3D models accurately predicted the frequency of the modes, whereas the amplitudes of the modes and associated energy were damped for the friction-dominant cases and augmented for non-frictional ones. The performance of the three turbulence models remained essentially similar, with slightly better predictions by RNG k-ε model in the case with the highest Reynolds number. Finally, the Q-criterion was used to identify vortices and study their dynamics, assisting on the identification of the differences between: i) the three-dimensional phenomenon (here reproduced), ii) its two-dimensional footprint in the free surface (experimental observations) and iii) the depth-averaged case (represented by 2D models). KW - coherent structures KW - hydraulic modelling KW - model performance KW - Proper Orthogonal Decomposition KW - Q-criterion Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.jher.2022.03.002 SN - 1570-6443 IS - In Press PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Grundmann, Jan Thimo A1 - Boden, Ralf A1 - Ceriotti, Matteo A1 - Dachwald, Bernd A1 - Dumont, Etienne A1 - Grimm, Christian D. A1 - Lange, Caroline A1 - Lichtenheldt, Roy A1 - Pelivan, Ivanka A1 - Peloni, Alessandro A1 - Riemann, Johannes A1 - Spröwitz, Tom A1 - Tardivel, Simon T1 - Soil to sail-asteroid landers on near-term sailcraft as an evolution of the GOSSAMER small spacecraft solar sail concept for in-situ characterization T2 - 5th IAA Planetary Defense Conference KW - multiple NEA rendezvous KW - solar sail KW - GOSSAMER-1 KW - MASCOT KW - asteroid sample return Y1 - 2017 N1 - 5th IAA Planetary Defense Conference – PDC 2017 15-19 May 2017, Tokyo, Japan ER - TY - CHAP A1 - Dachwald, Bernd A1 - Kahle, Ralph A1 - Wie, Bong T1 - Head-on impact deflection of NEAs: a case study for 99942 Apophis T2 - Planetary Defense Conference 2007 N2 - Near-Earth asteroid (NEA) 99942 Apophis provides a typical example for the evolution of asteroid orbits that lead to Earth-impacts after a close Earth-encounter that results in a resonant return. Apophis will have a close Earth-encounter in 2029 with potential very close subsequent Earth-encounters (or even an impact) in 2036 or later, depending on whether it passes through one of several less than 1 km-sized gravitational keyholes during its 2029-encounter. A pre-2029 kinetic impact is a very favorable option to nudge the asteroid out of a keyhole. The highest impact velocity and thus deflection can be achieved from a trajectory that is retrograde to Apophis orbit. With a chemical or electric propulsion system, however, many gravity assists and thus a long time is required to achieve this. We show in this paper that the solar sail might be the better propulsion system for such a mission: a solar sail Kinetic Energy Impactor (KEI) spacecraft could impact Apophis from a retrograde trajectory with a very high relative velocity (75-80 km/s) during one of its perihelion passages. The spacecraft consists of a 160 m × 160 m, 168 kg solar sail assembly and a 150 kg impactor. Although conventional spacecraft can also achieve the required minimum deflection of 1 km for this approx. 320 m-sized object from a prograde trajectory, our solar sail KEI concept also allows the deflection of larger objects. For a launch in 2020, we also show that, even after Apophis has flown through one of the gravitational keyholes in 2029, the solar sail KEI concept is still feasible to prevent Apophis from impacting the Earth, but many KEIs would be required for consecutive impacts to increase the total Earth-miss distance to a safe value Y1 - 2007 N1 - Planetary Defense Conference 2007, Wahington D.C., USA, 05-08 March 2007 SP - 1 EP - 12 ER - TY - JOUR A1 - Bhattarai, Aroj A1 - Horbach, Andreas A1 - Staat, Manfred A1 - Kowalczyk, Wojciech A1 - Tran, Thanh Ngoc T1 - Virgin passive colon biomechanics and a literature review of active contraction constitutive models JF - Biomechanics N2 - The objective of this paper is to present our findings on the biomechanical aspects of the virgin passive anisotropic hyperelasticity of the porcine colon based on equibiaxial tensile experiments. Firstly, the characterization of the intestine tissues is discussed for a nearly incompressible hyperelastic fiber-reinforced Holzapfel–Gasser–Ogden constitutive model in virgin passive loading conditions. The stability of the evaluated material parameters is checked for the polyconvexity of the adopted strain energy function using positive eigenvalue constraints of the Hessian matrix with MATLAB. The constitutive material description of the intestine with two collagen fibers in the submucosal and muscular layer each has been implemented in the FORTRAN platform of the commercial finite element software LS-DYNA, and two equibiaxial tensile simulations are presented to validate the results with the optical strain images obtained from the experiments. Furthermore, this paper also reviews the existing models of the active smooth muscle cells, but these models have not been computationally studied here. The review part shows that the constitutive models originally developed for the active contraction of skeletal muscle based on Hill’s three-element model, Murphy’s four-state cross-bridge chemical kinetic model and Huxley’s sliding-filament hypothesis, which are mainly used for arteries, are appropriate for numerical contraction numerical analysis of the large intestine. KW - virgin passive KW - strain energy function KW - smooth muscle contraction KW - viscoelasticity KW - damage Y1 - 2022 U6 - http://dx.doi.org/10.3390/biomechanics2020013 SN - 2673-7078 VL - 2 IS - 2 SP - 138 EP - 157 PB - MDPI CY - Basel ER - TY - CHAP A1 - Handschuh, Nils A1 - Stollenwerk, Dominik A1 - Borchert, Jörg T1 - Operation of thermal storage power plants under high renewable grid penetration T2 - NEIS 2021: Conference on Sustainable Energy Supply and Energy Storage Systems N2 - The planned coal phase-out in Germany by 2038 will lead to the dismantling of power plants with a total capacity of approx. 30 GW. A possible further use of these assets is the conversion of the power plants to thermal storage power plants; the use of these power plants on the day-ahead market is considerably limited by their technical parameters. In this paper, the influence of the technical boundary conditions on the operating times of these storage facilities is presented. For this purpose, the storage power plants were described as an MILP problem and two price curves, one from 2015 with a relatively low renewable penetration (33 %) and one from 2020 with a high renewable energy penetration (51 %) are compared. The operating times were examined as a function of the technical parameters and the critical influencing factors were investigated. The thermal storage power plant operation duration and the energy shifted with the price curve of 2020 increases by more than 25 % compared to 2015. KW - storage optimisation KW - storage dispatch KW - thermal storage Y1 - 2021 SN - 978-3-8007-5651-3 N1 - NEIS 2021: Conference on Sustainable Energy Supply and Energy Storage Systems. 13-14 September 2021. Hamburg, Germany SP - 261 EP - 265 PB - VDE Verlag CY - Berlin ER - TY - CHAP A1 - Kroniger, Daniel A1 - Horikawa, Atsushi A1 - Funke, Harald A1 - Pfäffle, Franziska A1 - Kishimoto, Tsuyoshi A1 - Okada, Koichi T1 - Experimental and numerical investigation on the effect of pressure on micromix hydrogen combustion T2 - ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition // Volume 3A: Combustion, Fuels, and Emissions N2 - The micromix (MMX) combustion concept is a DLN gas turbine combustion technology designed for high hydrogen content fuels. Multiple non-premixed miniaturized flames based on jet in cross-flow (JICF) are inherently safe against flashback and ensure a stable operation in various operative conditions. The objective of this paper is to investigate the influence of pressure on the micromix flame with focus on the flame initiation point and the NOx emissions. A numerical model based on a steady RANS approach and the Complex Chemistry model with relevant reactions of the GRI 3.0 mechanism is used to predict the reactive flow and NOx emissions at various pressure conditions. Regarding the turbulence-chemical interaction, the Laminar Flame Concept (LFC) and the Eddy Dissipation Concept (EDC) are compared. The numerical results are validated against experimental results that have been acquired at a high pressure test facility for industrial can-type gas turbine combustors with regard to flame initiation and NOx emissions. The numerical approach is adequate to predict the flame initiation point and NOx emission trends. Interestingly, the flame shifts its initiation point during the pressure increase in upstream direction, whereby the flame attachment shifts from anchoring behind a downstream located bluff body towards anchoring directly at the hydrogen jet. The LFC predicts this change and the NOx emissions more accurately than the EDC. The resulting NOx correlation regarding the pressure is similar to a non-premixed type combustion configuration. KW - NOx emissions KW - hydrogen KW - combustor KW - gas turbine Y1 - 2021 U6 - http://dx.doi.org/10.1115/GT2021-58926 N1 - ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. June 7–11, 2021. Virtual, Online. Paper No: GT2021-58926, V03AT04A025 ER - TY - CHAP A1 - Horikawa, Atsushi A1 - Okada, Kunio A1 - Yamaguchi, Masato A1 - Aoki, Shigeki A1 - Wirsum, Manfred A1 - Funke, Harald A1 - Kusterer, Karsten T1 - Combustor development and engine demonstration of micro-mix hydrogen combustion applied to M1A-17 gas turbine T2 - ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition // Volume 3B: Combustion, Fuels, and Emissions N2 - Kawasaki Heavy Industries, LTD. (KHI) has research and development projects for a future hydrogen society. These projects comprise the complete hydrogen cycle, including the production of hydrogen gas, the refinement and liquefaction for transportation and storage, and finally the utilization in a gas turbine for electricity and heat supply. Within the development of the hydrogen gas turbine, the key technology is stable and low NOx hydrogen combustion, namely the Dry Low NOx (DLN) hydrogen combustion. KHI, Aachen University of Applied Science, and B&B-AGEMA have investigated the possibility of low NOx micro-mix hydrogen combustion and its application to an industrial gas turbine combustor. From 2014 to 2018, KHI developed a DLN hydrogen combustor for a 2MW class industrial gas turbine with the micro-mix technology. Thereby, the ignition performance, the flame stability for equivalent rotational speed, and higher load conditions were investigated. NOx emission values were kept about half of the Air Pollution Control Law in Japan: 84ppm (O2-15%). Hereby, the elementary combustor development was completed. From May 2020, KHI started the engine demonstration operation by using an M1A-17 gas turbine with a co-generation system located in the hydrogen-fueled power generation plant in Kobe City, Japan. During the first engine demonstration tests, adjustments of engine starting and load control with fuel staging were investigated. On 21st May, the electrical power output reached 1,635 kW, which corresponds to 100% load (ambient temperature 20 °C), and thereby NOx emissions of 65 ppm (O2-15, 60 RH%) were verified. Here, for the first time, a DLN hydrogen-fueled gas turbine successfully generated power and heat. KW - industrial gas turbine KW - combustor development KW - engine demonstration KW - fuels KW - hydrogen Y1 - 2021 U6 - http://dx.doi.org/10.1115/GT2021-59666 N1 - ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. June 7–11, 2021. Virtual, Online. Paper No: GT2021-59666, V03BT04A014 ER - TY - CHAP A1 - Kroniger, Daniel A1 - Horikawa, Atsushi A1 - Funke, Harald A1 - Pfäffle, Franziska T1 - Numerical investigation of micromix hydrogen flames at different combustor pressure levels T2 - Proceedings of the International Conference on Power Engineering 2021 N2 - This study investigates the influence of pressure on the temperature distribution of the micromix (MMX) hydrogen flame and the NOx emissions. A steady computational fluid dynamic (CFD) analysis is performed by simulating a reactive flow with a detailed chemical reaction model. The numerical analysis is validated based on experimental investigations. A quantitative correlation is parametrized based on the numerical results. We find, that the flame initiation point shifts with increasing pressure from anchoring behind a downstream located bluff body towards anchoring upstream at the hydrogen jet. The numerical NOx emissions trend regarding to a variation of pressure is in good agreement with the experimental results. The pressure has an impact on both, the residence time within the maximum temperature region and on the peak temperature itself. In conclusion, the numerical model proved to be adequate for future prototype design exploration studies targeting on improving the operating range. KW - Gas turbine combustion KW - Hydrogen KW - NOx emissions KW - Flame temperature KW - Flame residence time Y1 - 2021 N1 - Proceedings of the International Conference on Power Engineering 2021 (ICOPE-2021). October 17 - 21, 2021. Kobe, Japan (Online) ER - TY - CHAP A1 - Dachwald, Bernd T1 - Solar sail performance requirements for missions to the outer solar system and beyond T2 - 55th International Astronautical Congress 2004 N2 - Solar sails enable missions to the outer solar system and beyond, although the solar radiation pressure decreases with the square of solar distance. For such missions, the solar sail may gain a large amount of energy by first making one or more close approaches to the sun. Within this paper, optimal trajectories for solar sail missions to the outer planets and into near interstellar space (200 AU) are presented. Thereby, it is shown that even near/medium-term solar sails with relatively moderate performance allow reasonable transfer times to the boundaries of the solar system. Y1 - 2004 U6 - http://dx.doi.org/10.2514/6.IAC-04-S.P.11 N1 - 55th International Astronautical Congress 2004 - Vancouver, Canada SP - 1 EP - 9 ER - TY - JOUR A1 - Peloni, Alessandro A1 - Ceriotti, Matteo A1 - Dachwald, Bernd T1 - Solar-sail trajectory design for a multiple near-earth-asteroid rendezvous mission JF - Journal of Guidance, Control, and Dynamics N2 - The scientific interest for near-Earth asteroids as well as the interest in potentially hazardous asteroids from the perspective of planetary defense led the space community to focus on near-Earth asteroid mission studies. A multiple near-Earth asteroid rendezvous mission with close-up observations of several objects can help to improve the characterization of these asteroids. This work explores the design of a solar-sail spacecraft for such a mission, focusing on the search of possible sequences of encounters and the trajectory optimization. This is done in two sequential steps: a sequence search by means of a simplified trajectory model and a set of heuristic rules based on astrodynamics, and a subsequent optimization phase. A shape-based approach for solar sailing has been developed and is used for the first phase. The effectiveness of the proposed approach is demonstrated through a fully optimized multiple near-Earth asteroid rendezvous mission. The results show that it is possible to visit five near-Earth asteroids within 10 years with near-term solar-sail technology. Y1 - 2016 U6 - http://dx.doi.org/10.2514/1.G000470 SN - 0731-5090 VL - 39 IS - 12 SP - 2712 EP - 2724 PB - AIAA CY - Reston, Va. ER - TY - CHAP A1 - Hoffschmidt, Bernhard A1 - Alexopoulos, Spiros A1 - Göttsche, Joachim A1 - Sauerborn, Markus A1 - Kaufhold, O. T1 - High Concentration Solar Collectors T2 - Comprehensive Renewable Energy (Second Edition) / Volume 3: Solar Thermal Systems: Components and Applications N2 - Solar thermal concentrated power is an emerging technology that provides clean electricity for the growing energy market. To the solar thermal concentrated power plant systems belong the parabolic trough, the Fresnel collector, the solar dish, and the central receiver system. For high-concentration solar collector systems, optical and thermal analysis is essential. There exist a number of measurement techniques and systems for the optical and thermal characterization of the efficiency of solar thermal concentrated systems. For each system, structure, components, and specific characteristics types are described. The chapter presents additionally an outline for the calculation of system performance and operation and maintenance topics. One main focus is set to the models of components and their construction details as well as different types on the market. In the later part of this article, different criteria for the choice of technology are analyzed in detail. KW - Central receiver system KW - Concentrated solar collector KW - Solar dish KW - Solar concentration Y1 - 2022 SN - 978-0-12-819734-9 U6 - http://dx.doi.org/10.1016/B978-0-12-819727-1.00058-3 SP - 198 EP - 245 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Hoffschmidt, Bernhard A1 - Alexopoulos, Spiros A1 - Rau, Christoph A1 - Sattler, Johannes, Christoph A1 - Anthrakidis, Anette A1 - Teixeira Boura, Cristiano José A1 - O’Connor, B. A1 - Chico Caminos, R.A. A1 - Rendón, C. A1 - Hilger, P. T1 - Concentrating solar power T2 - Comprehensive Renewable Energy (Second Edition) / Volume 3: Solar Thermal Systems: Components and Applications N2 - The focus of this chapter is the production of power and the use of the heat produced from concentrated solar thermal power (CSP) systems. The chapter starts with the general theoretical principles of concentrating systems including the description of the concentration ratio, the energy and mass balance. The power conversion systems is the main part where solar-only operation and the increase in operational hours. Solar-only operation include the use of steam turbines, gas turbines, organic Rankine cycles and solar dishes. The operational hours can be increased with hybridization and with storage. Another important topic is the cogeneration where solar cooling, desalination and of heat usage is described. Many examples of commercial CSP power plants as well as research facilities from the past as well as current installed and in operation are described in detail. The chapter closes with economic and environmental aspects and with the future potential of the development of CSP around the world. KW - Central receiver power plant KW - Concentrated systems KW - Gas turbine KW - Hybridization KW - Power conversion systems Y1 - 2022 SN - 978-0-12-819734-9 SP - 670 EP - 724 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Eggert, Mathias A1 - Kriska, Melina T1 - Gamification for software development processes – relevant affordances and design principles T2 - Proceedings of the 55th Hawaii International Conference on System Sciences N2 - A Gamified Information System (GIS) implements game concepts and elements, such as affordances and game design principles to motivate people. Based on the idea to develop a GIS to increase the motivation of software developers to perform software quality tasks, the research work at hand aims at investigating relevant requirements from that target group. Therefore, 14 interviews with software development experts are conducted and analyzed. According to the results, software developers prefer the affordances points, narrative storytelling in a multiplayer and a round-based setting. Furthermore, six design principles for the development of a GIS are derived. Y1 - 2022 SN - 978-0-9981331-5-7 U6 - http://dx.doi.org/10.24251/HICSS.2022.200 N1 - Hawaii International Conference on System Sciences (HICSS) 2022, 04.01.2022 – 07.01.2022 SP - 1614 EP - 1623 PB - HICSS Publishing CY - Honolulu ER - TY - JOUR A1 - Defosse, Jerome A1 - Kleinschmidt, Joris A1 - Schmutz, Axel A1 - Loop, Torsten A1 - Staat, Manfred A1 - Gatzweiler, Karl-Heinz A1 - Wappler, Frank A1 - Schieren, Mark T1 - Dental strain on maxillary incisors during tracheal intubation with double-lumen tubes and different laryngoscopy techniques - a blinded manikin study JF - Journal of Cardiothoracic and Vascular Anesthesia KW - anaesthetic complications KW - dental trauma KW - difficult airway KW - double-lumen tube intubation KW - videolaryngoscopy Y1 - 2022 U6 - http://dx.doi.org/10.1053/j.jvca.2022.02.017 SN - 1053-0770 VL - 36 IS - 8, Part B SP - 3021 EP - 3027 PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Mandekar, Swati A1 - Holland, Abigail A1 - Thielen, Moritz A1 - Behbahani, Mehdi A1 - Melnykowycz, Mark T1 - Advancing towards Ubiquitous EEG, Correlation of In-Ear EEG with Forehead EEG JF - Sensors N2 - Wearable EEG has gained popularity in recent years driven by promising uses outside of clinics and research. The ubiquitous application of continuous EEG requires unobtrusive form-factors that are easily acceptable by the end-users. In this progression, wearable EEG systems have been moving from full scalp to forehead and recently to the ear. The aim of this study is to demonstrate that emerging ear-EEG provides similar impedance and signal properties as established forehead EEG. EEG data using eyes-open and closed alpha paradigm were acquired from ten healthy subjects using generic earpieces fitted with three custom-made electrodes and a forehead electrode (at Fpx) after impedance analysis. Inter-subject variability in in-ear electrode impedance ranged from 20 kΩ to 25 kΩ at 10 Hz. Signal quality was comparable with an SNR of 6 for in-ear and 8 for forehead electrodes. Alpha attenuation was significant during the eyes-open condition in all in-ear electrodes, and it followed the structure of power spectral density plots of forehead electrodes, with the Pearson correlation coefficient of 0.92 between in-ear locations ELE (Left Ear Superior) and ERE (Right Ear Superior) and forehead locations, Fp1 and Fp2, respectively. The results indicate that in-ear EEG is an unobtrusive alternative in terms of impedance, signal properties and information content to established forehead EEG. KW - in-ear EEG KW - correlation KW - forehead EEG KW - impedance spectroscopy KW - biopotential electrodes Y1 - 2022 U6 - http://dx.doi.org/10.3390/s22041568 SN - 1424-8220 VL - 22 IS - 4 SP - 1 EP - 19 PB - MDPI CY - Basel ER - TY - JOUR A1 - Hagenkamp, Markus A1 - Blanke, Tobias A1 - Döring, Bernd T1 - Thermoelectric building temperature control: a potential assessment JF - International Journal of Energy and Environmental Engineering N2 - This study focuses on thermoelectric elements (TEE) as an alternative for room temperature control. TEE are semi-conductor devices that can provide heating and cooling via a heat pump effect without direct noise emissions and no refrigerant use. An efficiency evaluation of the optimal operating mode is carried out for different numbers of TEE, ambient temperatures, and heating loads. The influence of an additional heat recovery unit on system efficiency and an unevenly distributed heating demand are examined. The results show that TEE can provide heat at a coefficient of performance (COP) greater than one especially for small heating demands and high ambient temperatures. The efficiency increases with the number of elements in the system and is subject to economies of scale. The best COP exceeds six at optimal operating conditions. An additional heat recovery unit proves beneficial for low ambient temperatures and systems with few TEE. It makes COPs above one possible at ambient temperatures below 0 ∘C. The effect increases efficiency by maximal 0.81 (from 1.90 to 2.71) at ambient temperature 5 K below room temperature and heating demand Q˙h=100W but is subject to diseconomies of scale. Thermoelectric technology is a valuable option for electricity-based heat supply and can provide cooling and ventilation functions. A careful system design as well as an additional heat recovery unit significantly benefits the performance. This makes TEE superior to direct current heating systems and competitive to heat pumps for small scale applications with focus on avoiding noise and harmful refrigerants. Y1 - 2021 U6 - http://dx.doi.org/10.1007/s40095-021-00424-x N1 - Corresponding author: Markus Hagenkamp VL - 13 SP - 241 EP - 254 PB - Springer CY - Berlin ER - TY - JOUR A1 - Topçu, Murat A1 - Madabhushi, Gopal S.P. A1 - Staat, Manfred T1 - A generalized shear-lag theory for elastic stress transfer between matrix and fibres having a variable radius JF - International Journal of Solids and Structures N2 - A generalized shear-lag theory for fibres with variable radius is developed to analyse elastic fibre/matrix stress transfer. The theory accounts for the reinforcement of biological composites, such as soft tissue and bone tissue, as well as for the reinforcement of technical composite materials, such as fibre-reinforced polymers (FRP). The original shear-lag theory proposed by Cox in 1952 is generalized for fibres with variable radius and with symmetric and asymmetric ends. Analytical solutions are derived for the distribution of axial and interfacial shear stress in cylindrical and elliptical fibres, as well as conical and paraboloidal fibres with asymmetric ends. Additionally, the distribution of axial and interfacial shear stress for conical and paraboloidal fibres with symmetric ends are numerically predicted. The results are compared with solutions from axisymmetric finite element models. A parameter study is performed, to investigate the suitability of alternative fibre geometries for use in FRP. KW - Natural fibres KW - Polymer-matrix composites KW - Biocomposites KW - Stress concentrations KW - Finite element analysis Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.ijsolstr.2022.111464 SN - 0020-7683 VL - 239–240 IS - Art. No. 111464 PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Engemann, Heiko A1 - Cönen, Patrick A1 - Dawar, Harshal A1 - Du, Shengzhi A1 - Kallweit, Stephan T1 - A robot-assisted large-scale inspection of wind turbine blades in manufacturing using an autonomous mobile manipulator JF - Applied Sciences N2 - Wind energy represents the dominant share of renewable energies. The rotor blades of a wind turbine are typically made from composite material, which withstands high forces during rotation. The huge dimensions of the rotor blades complicate the inspection processes in manufacturing. The automation of inspection processes has a great potential to increase the overall productivity and to create a consistent reliable database for each individual rotor blade. The focus of this paper is set on the process of rotor blade inspection automation by utilizing an autonomous mobile manipulator. The main innovations include a novel path planning strategy for zone-based navigation, which enables an intuitive right-hand or left-hand driving behavior in a shared human–robot workspace. In addition, we introduce a new method for surface orthogonal motion planning in connection with large-scale structures. An overall execution strategy controls the navigation and manipulation processes of the long-running inspection task. The implemented concepts are evaluated in simulation and applied in a real-use case including the tip of a rotor blade form. KW - mobile manipulation KW - large-scale inspection KW - wind turbine production KW - autonomous navigation KW - surface-orthogonal path planning Y1 - 2021 U6 - http://dx.doi.org/10.3390/app11199271 SN - 2076-3417 N1 - Belongs to the Special Issue "Advances in Industrial Robotics and Intelligent Systems" VL - 11 IS - 19 SP - 1 EP - 22 PB - MDPI CY - Basel ER - TY - CHAP A1 - Nikolovski, Gjorgji A1 - Reke, Michael A1 - Elsen, Ingo A1 - Schiffer, Stefan T1 - Machine learning based 3D object detection for navigation in unstructured environments T2 - 2021 IEEE Intelligent Vehicles Symposium Workshops (IV Workshops) N2 - In this paper we investigate the use of deep neural networks for 3D object detection in uncommon, unstructured environments such as in an open-pit mine. While neural nets are frequently used for object detection in regular autonomous driving applications, more unusual driving scenarios aside street traffic pose additional challenges. For one, the collection of appropriate data sets to train the networks is an issue. For another, testing the performance of trained networks often requires tailored integration with the particular domain as well. While there exist different solutions for these problems in regular autonomous driving, there are only very few approaches that work for special domains just as well. We address both the challenges above in this work. First, we discuss two possible ways of acquiring data for training and evaluation. That is, we evaluate a semi-automated annotation of recorded LIDAR data and we examine synthetic data generation. Using these datasets we train and test different deep neural network for the task of object detection. Second, we propose a possible integration of a ROS2 detector module for an autonomous driving platform. Finally, we present the performance of three state-of-the-art deep neural networks in the domain of 3D object detection on a synthetic dataset and a smaller one containing a characteristic object from an open-pit mine. KW - 3D object detection KW - LiDAR KW - autonomous driving KW - Deep learning KW - Three-dimensional displays Y1 - 2021 SN - 978-1-6654-7921-9 U6 - http://dx.doi.org/10.1109/IVWorkshops54471.2021.9669218 N1 - 2021 IEEE Intelligent Vehicles Symposium Workshops (IV Workshops), 11-17 July 2021, Nagoya, Japan. SP - 236 EP - 242 PB - IEEE ER - TY - CHAP A1 - Haugg, Albert Thomas A1 - Kreyer, Jörg A1 - Kemper, Hans A1 - Hatesuer, Katerina A1 - Esch, Thomas T1 - Heat exchanger for ORC. adaptability and optimisation potentials T2 - IIR International Rankine 2020 Conference N2 - The recovery of waste heat requires heat exchangers to extract it from a liquid or gaseous medium into another working medium, a refrigerant. In Organic Rankine Cycles (ORC) on Combustion Engines there are two major heat sources, the exhaust gas and the water/glycol fluid from the engine’s cooling circuit. A heat exchanger design must be adapted to the different requirements and conditions resulting from the heat sources, fluids, system configurations, geometric restrictions, and etcetera. The Stacked Shell Cooler (SSC) is a new and very specific design of a plate heat exchanger, created by AKG, which allows with a maximum degree of freedom the optimization of heat exchange rate and the reduction of the related pressure drop. This optimization in heat exchanger design for ORC systems is even more important, because it reduces the energy consumption of the system and therefore maximizes the increase in overall efficiency of the engine. Y1 - 2020 U6 - http://dx.doi.org/10.18462/iir.rankine.2020.1224 N1 - Conference: IIR International Rankine 2020 Conference - Heating, Cooling, Power Generation. Glasgow, 2020. ER - TY - CHAP A1 - Schänzle, Christian A1 - Altherr, Lena A1 - Ederer, Thorsten A1 - Pelz, Peter T1 - TOR – Towards the energetically optimal ventilation system KW - Energy KW - Efficiency KW - Ventilation System KW - Discrete Optimisation KW - TGA Y1 - 2015 N1 - EST 2015, Karlsruhe, 19-21 Mai 2015 ER - TY - CHAP A1 - Lorenz, Imke-Sophie A1 - Altherr, Lena A1 - Pelz, Peter F. T1 - Resilience enhancement of critical infrastructure – graph-theoretical resilience analysis of the water distribution system in the German city of Darmstadt T2 - 14th WCEAM Proceedings N2 - Water suppliers are faced with the great challenge of achieving high-quality and, at the same time, low-cost water supply. Since climatic and demographic influences will pose further challenges in the future, the resilience enhancement of water distribution systems (WDS), i.e. the enhancement of their capability to withstand and recover from disturbances, has been in particular focus recently. To assess the resilience of WDS, graph-theoretical metrics have been proposed. In this study, a promising approach is first physically derived analytically and then applied to assess the resilience of the WDS for a district in a major German City. The topology based resilience index computed for every consumer node takes into consideration the resistance of the best supply path as well as alternative supply paths. This resistance of a supply path is derived to be the dimensionless pressure loss in the pipes making up the path. The conducted analysis of a present WDS provides insight into the process of actively influencing the resilience of WDS locally and globally by adding pipes. The study shows that especially pipes added close to the reservoirs and main branching points in the WDS result in a high resilience enhancement of the overall WDS. KW - Resilient infrastructure KW - Resilience assessment KW - Resilience metric graph theory KW - Water distribution system KW - Case study Y1 - 2020 SN - 978-3-030-64228-0 SN - 978-3-030-64227-3 U6 - http://dx.doi.org/10.1007/978-3-030-64228-0_13 N1 - 14th WCEAM Proceedings. World Congress on Engineering Asset Management, 28-31 July 2019, Singapore Part of the Lecture Notes in Mechanical Engineering book series (LNME) SP - 137 EP - 149 PB - Springer CY - Cham ER - TY - CHAP A1 - Leise, Philipp A1 - Altherr, Lena T1 - Experimental evaluation of resilience metrics in a fluid system T2 - Mastering Uncertainty in Mechanical Engineering Y1 - 2021 SN - 978-3-030-78356-3 N1 - Unterkapitel des Kapitels "Strategies for Mastering Uncertainty" SP - 442 EP - 447 PB - Springer CY - Cham ER - TY - CHAP A1 - Altherr, Lena A1 - Leise, Philipp A1 - Pfetsch, Marc E. A1 - Schmitt, Andreas T1 - Optimal design of resilient technical systems on the example of water supply systems T2 - Mastering Uncertainty in Mechanical Engineering Y1 - 2021 SN - 978-3-030-78356-3 N1 - Unterkapitel des Kapitels "Strategies for Mastering Uncertainty" SP - 429 EP - 433 PB - Springer CY - Cham ER - TY - CHAP A1 - Altherr, Lena A1 - Leise, Philipp T1 - Resilience as a concept for mastering uncertainty T2 - Mastering Uncertainty in Mechanical Engineering Y1 - 2021 SN - 978-3-030-78353-2 U6 - http://dx.doi.org/10.1007/978-3-030-78354-9 N1 - Unterkapitel 6.3.1 des Kapitels "Strategies for Mastering Uncertainty" SP - 412 EP - 417 PB - Springer CY - Cham ER - TY - CHAP A1 - Golland, Alexander T1 - Struggling with users’ consent: Economic approach to solve the issue of coupling T2 - Turning Point in Data Protection Law Y1 - 2020 SN - 978-3-8487-6909-4 U6 - http://dx.doi.org/10.5771/9783748921561-121 SP - 121 EP - 126 PB - Nomos CY - Baden-Baden ER - TY - CHAP A1 - Golland, Alexander A1 - Ohrtmann, Jan-Peter T1 - Video surveillance: The supervisory authorities’ view andrecent case law T2 - Turning Point in Data Protection Law Y1 - 2020 SN - 978-3-8487-6909-4 U6 - http://dx.doi.org/10.5771/9783748921561-175 SP - 175 EP - 178 PB - Nomos CY - Baden-Baden ER - TY - JOUR A1 - Pöttgen, Philipp A1 - Ederer, Thorsten A1 - Altherr, Lena A1 - Pelz, Peter F. T1 - Developing a control strategy for booster stations under uncertain load JF - Applied Mechanics and Materials N2 - Booster stations can fulfill a varying pressure demand with high energy-efficiency, because individual pumps can be deactivated at smaller loads. Although this is a seemingly simple approach, it is not easy to decide precisely when to activate or deactivate pumps. Contemporary activation controls derive the switching points from the current volume flow through the system. However, it is not measured directly for various reasons. Instead, the controller estimates the flow based on other system properties. This causes further uncertainty for the switching decision. In this paper, we present a method to find a robust, yet energy-efficient activation strategy. KW - Technical Operations Research (TOR) KW - Booster Station KW - Pump System KW - Discrete Optimization Y1 - 2015 SN - 1662-7482 U6 - http://dx.doi.org/10.4028/www.scientific.net/AMM.807.241 N1 - Ebenfalls weltweit einsehbar unter: http://wl.fst.tu-darmstadt.de/wl/publications/paper_151123_SFB805_ ICUME_Developing_a_Control_Strategy_for_Booster_Stations_under_Uncertain_Load_poettgen_ederer_pelz_altherr.pdf VL - 807 IS - 807 SP - 241 EP - 246 PB - Trans Tech Publications CY - Bäch ER - TY - JOUR A1 - Altherr, Lena A1 - Ederer, Thorsten A1 - Pöttgen, Philipp A1 - Lorenz, Ulf A1 - Pelz, Peter F. ED - Pelz, Peter F. ED - Groche, Peter T1 - Multicriterial optimization of technical systems considering multiple load and availability scenarios JF - Applied Mechanics and Materials N2 - Cheap does not imply cost-effective -- this is rule number one of zeitgeisty system design. The initial investment accounts only for a small portion of the lifecycle costs of a technical system. In fluid systems, about ninety percent of the total costs are caused by other factors like power consumption and maintenance. With modern optimization methods, it is already possible to plan an optimal technical system considering multiple objectives. In this paper, we focus on an often neglected contribution to the lifecycle costs: downtime costs due to spontaneous failures. Consequently, availability becomes an issue. KW - sustainability KW - availability KW - energy efficiency KW - mixed-integer linear programming KW - system synthesis Y1 - 2015 SN - 1660-9336 U6 - http://dx.doi.org/10.4028/www.scientific.net/AMM.807.247 VL - 807 SP - 247 EP - 256 ER - TY - CHAP A1 - Altherr, Lena A1 - Ederer, Thorsten A1 - Farnetane, Lucas S. A1 - Pöttgen, Philipp A1 - Vergé, Angela A1 - Pelz, Peter F. T1 - Multicriterial design of a hydrostatic transmission system via mixed-integer programming T2 - Operations Research Proceedings 2015 N2 - In times of planned obsolescence the demand for sustainability keeps growing. Ideally, a technical system is highly reliable, without failures and down times due to fast wear of single components. At the same time, maintenance should preferably be limited to pre-defined time intervals. Dispersion of load between multiple components can increase a system’s reliability and thus its availability inbetween maintenance points. However, this also results in higher investment costs and additional efforts due to higher complexity. Given a specific load profile and resulting wear of components, it is often unclear which system structure is the optimal one. Technical Operations Research (TOR) finds an optimal structure balancing availability and effort. We present our approach by designing a hydrostatic transmission system. Y1 - 2017 SN - 978-3-319-42901-4 SN - 978-3-319-42902-1 U6 - http://dx.doi.org/10.1007/978-3-319-42902-1_41 N1 - International Conference of the German, Austrian and Swiss Operations Research Societies (GOR, ÖGOR, SVOR/ASRO), University of Vienna, Austria, September 1-4, 2015 SP - 301 EP - 307 PB - Springer CY - Cham ER - TY - JOUR A1 - Pöttgen, Philipp A1 - Ederer, Thorsten A1 - Altherr, Lena A1 - Lorenz, Ulf A1 - Pelz, Peter F. T1 - Examination and optimization of a heating circuit for energy-efficient buildings JF - Energy Technology N2 - The conference center darmstadtium in Darmstadt is a prominent example of energy efficient buildings. Its heating system consists of different source and consumer circuits connected by a Zortström reservoir. Our goal was to reduce the energy costs of the system as much as possible. Therefore, we analyzed its supply circuits. The first step towards optimization is a complete examination of the system: 1) Compilation of an object list for the system, 2) collection of the characteristic curves of the components, and 3) measurement of the load profiles of the heat and volume-flow demand. Instead of modifying the system manually and testing the solution by simulation, the second step was the creation of a global optimization program. The objective was to minimize the total energy costs for one year. We compare two different topologies and show opportunities for significant savings. KW - energy transfer KW - heating system KW - programming KW - system optimization KW - technical operations research Y1 - 2015 SN - 2194-4296 U6 - http://dx.doi.org/10.1002/ente.201500252 VL - 4 IS - 1 SP - 136 EP - 144 PB - WILEY-VCH Verlag CY - Weinheim ER - TY - CHAP A1 - Altherr, Lena A1 - Dörig, Bastian A1 - Ederer, Thorsten A1 - Pelz, Peter Franz A1 - Pfetsch, Marc A1 - Wolf, Jan T1 - A mixed-integer nonlinear program for the design of gearboxes T2 - Operations Research Proceedings 2016 N2 - Gearboxes are mechanical transmission systems that provide speed and torque conversions from a rotating power source. Being a central element of the drive train, they are relevant for the efficiency and durability of motor vehicles. In this work, we present a new approach for gearbox design: Modeling the design problem as a mixed-integer nonlinear program (MINLP) allows us to create gearbox designs from scratch for arbitrary requirements and—given enough time—to compute provably globally optimal designs for a given objective. We show how different degrees of freedom influence the runtime and present an exemplary solution. Y1 - 2017 SN - 978-3-319-55701-4 U6 - http://dx.doi.org/10.1007/978-3-319-55702-1_31 SP - 227 EP - 233 PB - Springer CY - Cham ER - TY - JOUR A1 - Altherr, Lena A1 - Brötz, Nicolas A1 - Dietrich, Ingo A1 - Gally, Tristan A1 - Geßner, Felix A1 - Kloberdanz, Hermann A1 - Leise, Philipp A1 - Pelz, Peter Franz A1 - Schlemmer, Pia A1 - Schmitt, Andreas T1 - Resilience in mechanical engineering - a concept for controlling uncertainty during design, production and usage phase of load-carrying structures JF - Applied Mechanics and Materials N2 - Resilience as a concept has found its way into different disciplines to describe the ability of an individual or system to withstand and adapt to changes in its environment. In this paper, we provide an overview of the concept in different communities and extend it to the area of mechanical engineering. Furthermore, we present metrics to measure resilience in technical systems and illustrate them by applying them to load-carrying structures. By giving application examples from the Collaborative Research Centre (CRC) 805, we show how the concept of resilience can be used to control uncertainty during different stages of product life. Y1 - 2018 SN - 1662-7482 U6 - http://dx.doi.org/10.4028/www.scientific.net/AMM.885.187 VL - 885 SP - 187 EP - 198 PB - Trans Tech Publications CY - Bäch ER - TY - CHAP A1 - Schänzle, Christian A1 - Altherr, Lena A1 - Ederer, Thorsten A1 - Lorenz, Ulf A1 - Pelz, Peter F. T1 - As good as it can be: Ventilation system design by a combined scaling and discrete optimization method T2 - Proceedings of FAN 2015 N2 - The understanding that optimized components do not automatically lead to energy-efficient systems sets the attention from the single component on the entire technical system. At TU Darmstadt, a new field of research named Technical Operations Research (TOR) has its origin. It combines mathematical and technical know-how for the optimal design of technical systems. We illustrate our optimization approach in a case study for the design of a ventilation system with the ambition to minimize the energy consumption for a temporal distribution of diverse load demands. By combining scaling laws with our optimization methods we find the optimal combination of fans and show the advantage of the use of multiple fans. Y1 - 2015 N1 - Proceedings of FAN 2015, Lyon (France), 15 – 17 April 2015 SP - 1 EP - 11 ER - TY - CHAP A1 - Altherr, Lena A1 - Ederer, Thorsten A1 - Schänzle, Christian A1 - Lorenz, Ulf A1 - Pelz, Peter F. T1 - Algorithmic system design using scaling and affinity laws T2 - Operations Research Proceedings 2015 N2 - Energy-efficient components do not automatically lead to energy-efficient systems. Technical Operations Research (TOR) shifts the focus from the single component to the system as a whole and finds its optimal topology and operating strategy simultaneously. In previous works, we provided a preselected construction kit of suitable components for the algorithm. This approach may give rise to a combinatorial explosion if the preselection cannot be cut down to a reasonable number by human intuition. To reduce the number of discrete decisions, we integrate laws derived from similarity theory into the optimization model. Since the physical characteristics of a production series are similar, it can be described by affinity and scaling laws. Making use of these laws, our construction kit can be modeled more efficiently: Instead of a preselection of components, it now encompasses whole model ranges. This allows us to significantly increase the number of possible set-ups in our model. In this paper, we present how to embed this new formulation into a mixed-integer program and assess the run time via benchmarks. We present our approach on the example of a ventilation system design problem. KW - Optimal Topology KW - Piecewise Linearization KW - Ventilation System KW - Similarity Theory Y1 - 2017 SN - 978-3-319-42901-4 SN - 978-3-319-42902-1 U6 - http://dx.doi.org/10.1007/978-3-319-42902-1 N1 - International Conference of the German, Austrian and Swiss Operations Research Societies (GOR, ÖGOR, SVOR/ASRO), University of Vienna, Austria, September 1-4, 2015 SP - 605 EP - 611 PB - Springer CY - Cham ER -