Article
Refine
Year of publication
- 2021 (109) (remove)
Institute
- Fachbereich Medizintechnik und Technomathematik (39)
- IfB - Institut für Bioengineering (27)
- Fachbereich Wirtschaftswissenschaften (16)
- INB - Institut für Nano- und Biotechnologien (15)
- Fachbereich Luft- und Raumfahrttechnik (12)
- Fachbereich Chemie und Biotechnologie (11)
- Fachbereich Bauingenieurwesen (8)
- Fachbereich Energietechnik (7)
- Fachbereich Elektrotechnik und Informationstechnik (6)
- Fachbereich Maschinenbau und Mechatronik (4)
Document Type
- Article (109) (remove)
Keywords
- Principal component analysis (2)
- capacitive field-effect sensor (2)
- constructive alignment (2)
- examination (2)
- harmonic radar (2)
- long-term retention (2)
- multimodal (2)
- practical learning (2)
- Aircraft sizing (1)
- AlterG (1)
- Architektur (1)
- Authenticity (1)
- Bacillus sp (1)
- Bemessung (1)
- Biosolubilization (1)
- Bloom’s Taxonomy (1)
- Bone quality and biomechanics (1)
- Bootstrap (1)
- Boundary integral equations (1)
- CFD (1)
- Capacitive field-effect sensor (1)
- CellDrum (1)
- Competence Developing Games (1)
- DLR-ESTEC GOSSAMER roadmap for solar sailing (1)
- Deuterated solvents (1)
- Deuterium NMR (1)
- Deutschland (1)
- Drinfeld modules (1)
- Earthquake (1)
- Empirical process (1)
- Environmental impact (1)
- Erdbebeneinwirkung (1)
- Frame structure (1)
- Frequency mixing magnetic detection (1)
- Functional Delta Method (1)
- GOSSAMER-1 (1)
- Game-based learning (1)
- Glaucoma (1)
- Hadamard differentiability (1)
- Helmholtz equation (1)
- Heparin (1)
- Hyperdifferentials (1)
- IR (1)
- IR spectroscopy (1)
- IT security education (1)
- Interior Neumann eigenvalues (1)
- Keyword analysis (1)
- LPS (1)
- Label-free detection (1)
- Langevin theory (1)
- Linear discriminant analysis (1)
- MUT measurement; scanner (1)
- Magnetic nanoparticles (1)
- Manufacturer (1)
- Mauerwerksbauten (1)
- Micromagnetic simulation (1)
- Modelica (1)
- Multi-storey (1)
- Muscle Fascicle (1)
- Muscle Force (1)
- Nonequilibrium dynamics (1)
- Numerics (1)
- Ocular blood flow (1)
- Paired sample (1)
- Parasitic drag (1)
- Piping (1)
- Plant virus (1)
- Potential theory (1)
- Powertrain (1)
- PushoverAnalysen (1)
- RVA (1)
- Radar (1)
- SFCW (1)
- Septic cardiomyopathy (1)
- Simulation (1)
- Skeletal muscle (1)
- Small Aral Sea (1)
- Small spacecraft (1)
- Soft independent modeling of class analogy (1)
- Solar sail (1)
- Standardization (1)
- Stiffness (1)
- TMV adsorption (1)
- Tank (1)
- Ta₂O₅ gate (1)
- Tendon Rupture (1)
- Tendons (1)
- Tobacco mosaic virus (TMV) (1)
- Transcendence (1)
- UAV (1)
- Ultrasound (1)
- VOP compression (1)
- Vascular response (1)
- Verhaltensbeiwerte (1)
- Visual field asymmetry (1)
- Wasserbau (1)
- Wasserwirtschaft (1)
- Zeta potential (1)
- acetoin (1)
- acetoin reductase (1)
- actin cytoskeleton (1)
- actuator-sensor system (1)
- alcoholic beverages (1)
- autonomous navigation (1)
- bioburdens (1)
- biosensors (1)
- body imaging at UHF MRI (1)
- building energy modelling (1)
- building energy simulation (1)
- business culture (1)
- capacitive EIS sensor (1)
- capacitive electrolyte–insulator–semiconductor sensors (1)
- capacitive field-effect sensors (1)
- cardiomyocyte biomechanics (1)
- change (1)
- colorization (1)
- control gate (1)
- crop yield (1)
- cyber-physical production systems (1)
- detection of charged macromolecules (1)
- digital factory (1)
- drop jump (1)
- ecological structure (1)
- enzymatic biosensor (1)
- enzyme kinetics (1)
- equivalent circuit (1)
- event-based simulation (1)
- field-effect sensor (1)
- frequency mixing magnetic detection (1)
- gait (1)
- genetic algorithm (1)
- global optimization (1)
- gold nanoparticles (1)
- graphene oxide (1)
- harmonic radar tags (1)
- heat demand (1)
- heat transfer coefficient (1)
- humic acid (1)
- hyper-gravity (1)
- hypo-gravity (1)
- industrial agents (1)
- integrated transmit coil arrays (1)
- intraclass correlation coefficient (1)
- large-scale inspection (1)
- layer-by-layer technique (1)
- light-addressable electrode (1)
- light-addressable potentiometric sensor (1)
- lignite (1)
- locomotion (1)
- low-rank coal (1)
- magnetic nanoparticles (1)
- management (1)
- metagenomics (1)
- microbial diversity (1)
- microfluidics (1)
- microwave measurements (1)
- mobile manipulation (1)
- motivation (1)
- multi-agent systems (1)
- multianalyte detection (1)
- multiplex detection (1)
- muscle fascicle behavior (1)
- muscle mechanics (1)
- nanomaterials (1)
- nonlinear VNA measurements (1)
- nonlinear radar (1)
- on-chip integrated addressable EISCAP sensors (1)
- parabolic flight (1)
- penicillin (1)
- penicillinase (1)
- photoelectrochemistry (1)
- plant virus detection (1)
- polyaniline (1)
- polystyrene sulfonate (1)
- qNMR (1)
- rehabilitation (1)
- running (1)
- sarcomere operating length (1)
- series elastic element behavior (1)
- shotgun sequencing (1)
- shoulder (1)
- soil amendment (1)
- soil health (1)
- soil remediation (1)
- sprint start (1)
- standard error of measurement (1)
- sterility tests (1)
- sterilization efficacy (1)
- sterilization methods (1)
- stochastic optimization (1)
- stretch reflex (1)
- surface-orthogonal path planning (1)
- t-modules (1)
- test-retest reliability (1)
- titanium dioxide photoanode (1)
- tobacco mosaic virus (TMV) (1)
- transponder (1)
- ultrasonography (1)
- ultrasound imaging (1)
- unloading (1)
- validation methods (1)
- walking (1)
- wind turbine production (1)
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.
The hot spots conjecture is only known to be true for special geometries. This paper shows numerically that the hot spots conjecture can fail to be true for easy to construct bounded domains with one hole. The underlying eigenvalue problem for the Laplace equation with Neumann boundary condition is solved with boundary integral equations yielding a non-linear eigenvalue problem. Its discretization via the boundary element collocation method in combination with the algorithm by Beyn yields highly accurate results both for the first non-zero eigenvalue and its corresponding eigenfunction which is due to superconvergence. Additionally, it can be shown numerically that the ratio between the maximal/minimal value inside the domain and its maximal/minimal value on the boundary can be larger than 1 + 10− 3. Finally, numerical examples for easy to construct domains with up to five holes are provided which fail the hot spots conjecture as well.
Stretch-shortening type actions are characterized by lengthening of the pre-activated muscle-tendon unit (MTU) in the eccentric phase immediately followed by muscle shortening. Under 1 g, pre-activity before and muscle activity after ground contact, scale muscle stiffness, which is crucial for the recoil properties of the MTU in the subsequent push-off. This study aimed to examine the neuro-mechanical coupling of the stretch-shortening cycle in response to gravity levels ranging from 0.1 to 2 g. During parabolic flights, 17 subjects performed drop jumps while electromyography (EMG) of the lower limb muscles was combined with ultrasound images of the gastrocnemius medialis, 2D kinematics and kinetics to depict changes in energy management and performance. Neuro-mechanical coupling in 1 g was characterized by high magnitudes of pre-activity and eccentric muscle activity allowing an isometric muscle behavior during ground contact. EMG during pre-activity and the concentric phase systematically increased from 0.1 to 1 g. Below 1 g the EMG in the eccentric phase was diminished, leading to muscle lengthening and reduced MTU stretches. Kinetic energy at take-off and performance were decreased compared to 1 g. Above 1 g, reduced EMG in the eccentric phase was accompanied by large MTU and muscle stretch, increased joint flexion amplitudes, energy loss and reduced performance. The energy outcome function established by linear mixed model reveals that the central nervous system regulates the extensor muscles phase- and load-specifically. In conclusion, neuro-mechanical coupling appears to be optimized in 1 g. Below 1 g, the energy outcome is compromised by reduced muscle stiffness. Above 1 g, loading progressively induces muscle lengthening, thus facilitating energy dissipation.
Test-retest reliability of the internal shoulder rotator muscles' stretch reflex in healthy men
(2021)
Until now the reproducibility of the short latency stretch reflex of the internal rotator muscles of the glenohumeral joint has not been identified. Twenty-three healthy male participants performed three sets of external shoulder rotation stretches with various pre-activation levels on two different dates of measurement to assess test-retest reliability. All stretches were applied with a dynamometer acceleration of 104°/s2 and a velocity of 150°/s. Electromyographical response was measured via surface EMG. Reflex latencies showed a pre-activation effect (ƞ2 = 0,355). ICC ranged from 0,735 to 0,909 indicating an overall “good” relative reliability. SRD 95% lay between ±7,0 to ±12,3 ms.. The reflex gain showed overall poor test-retest reproducibility. The chosen methodological approach presented a suitable test protocol for shoulder muscles stretch reflex latency evaluation. A proof-of-concept study to validate the presented methodical approach in shoulder involvement including subjects with clinically relevant conditions is recommended.
In the context of the Solvency II directive, the operation of an internal risk model is a possible way for risk assessment and for the determination of the solvency capital requirement of an insurance company in the European Union. A Monte Carlo procedure is customary to generate a model output. To be compliant with the directive, validation of the internal risk model is conducted on the basis of the model output. For this purpose, we suggest a new test for checking whether there is a significant change in the modeled solvency capital requirement. Asymptotic properties of the test statistic are investigated and a bootstrap approximation is justified. A simulation study investigates the performance of the test in the finite sample case and confirms the theoretical results. The internal risk model and the application of the test is illustrated in a simplified example. The method has more general usage for inference of a broad class of law-invariant and coherent risk measures on the basis of a paired sample.
The transition within transportation towards battery electric vehicles can lead to a more sustainable future. To account for the development goal ‘climate action’ stated by the United Nations, it is mandatory, within the conceptual design phase, to derive energy-efficient system designs. One barrier is the uncertainty of the driving behaviour within the usage phase. This uncertainty is often addressed by using a stochastic synthesis process to derive representative driving cycles and by using cycle-based optimization. To deal with this uncertainty, a new approach based on a stochastic optimization program is presented. This leads to an optimization model that is solved with an exact solver. It is compared to a system design approach based on driving cycles and a genetic algorithm solver. Both approaches are applied to find efficient electric powertrains with fixed-speed and multi-speed transmissions. Hence, the similarities, differences and respective advantages of each optimization procedure are discussed.
The treatment method to deactivate viable microorganisms from objects or products is termed sterilization. There are multiple forms of sterilization, each intended to be applied for a specific target, which depends on—but not limited to—the thermal, physical, and chemical stability of that target. Herein, an overview on the currently used sterilization processes in the global market is provided. Different sterilization techniques are grouped under a category that describes the method of treatment: radiation (gamma, electron beam, X-ray, and ultraviolet), thermal (dry and moist heat), and chemical (ethylene oxide, ozone, chlorine dioxide, and hydrogen peroxide). For each sterilization process, the typical process parameters as defined by regulations and the mode of antimicrobial activity are summarized. Finally, the recommended microorganisms that are used as biological indicators to validate sterilization processes in accordance with the rules that are established by various regulatory agencies are summarized.
In this study, a recently proposed NMR standardization approach by 2H integral of deuterated solvent for quantitative multicomponent analysis of complex mixtures is presented. As a proof of principle, the existing NMR routine for the analysis of Aloe vera products was modified. Instead of using absolute integrals of targeted compounds and internal standard (nicotinamide) from 1H-NMR spectra, quantification was performed based on the ratio of a particular 1H-NMR compound integral and 2H-NMR signal of deuterated solvent D2O. Validation characteristics (linearity, repeatability, accuracy) were evaluated and the results showed that the method has the same precision as internal standardization in case of multicomponent screening. Moreover, a dehydration process by freeze drying is not necessary for the new routine. Now, our NMR profiling of A. vera products needs only limited sample preparation and data processing. The new standardization methodology provides an appealing alternative for multicomponent NMR screening. In general, this novel approach, using standardization by 2H integral, benefits from reduced sample preparation steps and uncertainties, and is recommended in different application areas (purity determination, forensics, pharmaceutical analysis, etc.).
Past earthquakes demonstrated the high vulnerability of industrial facilities equipped with complex process technologies leading to serious damage of process equipment and multiple and simultaneous release of hazardous substances. Nonetheless, current standards for seismic design of industrial facilities are considered inadequate to guarantee proper safety conditions against exceptional events entailing loss of containment and related consequences. On these premises, the SPIF project -Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities- was proposed within the framework of the European H2020 SERA funding scheme. In detail, the objective of the SPIF project is the investigation of the seismic behaviour of a representative industrial multi-storey frame structure equipped with complex process components by means of shaking table tests. Along this main vein and in a performance-based design perspective, the issues investigated in depth are the interaction between a primary moment resisting frame (MRF) steel structure and secondary process components that influence the performance of the whole system; and a proper check of floor spectra predictions. The evaluation of experimental data clearly shows a favourable performance of the MRF structure, some weaknesses of local details due to the interaction between floor crossbeams and process components and, finally, the overconservatism of current design standards w.r.t. floor spectra predictions.
Achilles tendon rupture (ATR) patients have persistent functional deficits in the triceps surae muscle–tendon unit (MTU). The complex remodeling of the MTU accompanying these deficits remains poorly understood. The purpose of the present study was to associate in vivo and in silico data to investigate the relations between changes inMTU properties and strength deficits inATR patients. Methods: Elevenmale subjects who had undergone surgical repair of complete unilateral ATR were examined 4.6 ± 2.0 (mean ± SD) yr after rupture. Gastrocnemius medialis (GM) tendon stiffness, morphology, and muscle architecture were determined using ultrasonography. The force–length relation of the plantar flexor muscles was assessed at five ankle joint angles. In addition, simulations (OpenSim) of the GM MTU force–length properties were performed with various iterations of MTU properties found between the unaffected and the affected side. Results: The affected side of the patients displayed a longer, larger, and stiffer GM tendon (13% ± 10%, 105% ± 28%, and 54% ± 24%, respectively) compared with the unaffected side. The GM muscle fascicles of the affected side were shorter (32% ± 12%) and with greater pennation angles (31% ± 26%). A mean deficit in plantarflexion moment of 31% ± 10% was measured. Simulations indicate that pairing an intact muscle with a longer tendon shifts the optimal angular range of peak force outside physiological angular ranges, whereas the shorter muscle fascicles and tendon stiffening seen in the affected side decrease this shift, albeit incompletely. Conclusions: These results suggest that the substantial changes in MTU properties found in ATR patients may partly result from compensatory remodeling, although this process appears insufficient to fully restore muscle function.
Biologically sensitive field-effect devices (BioFEDs) advantageously combine the electronic field-effect functionality with the (bio)chemical receptor’s recognition ability for (bio)chemical sensing. In this review, basic and widely applied device concepts of silicon-based BioFEDs (ion-sensitive field-effect transistor, silicon nanowire transistor, electrolyte-insulator-semiconductor capacitor, light-addressable potentiometric sensor) are presented and recent progress (from 2019 to early 2021) is discussed. One of the main advantages of BioFEDs is the label-free sensing principle enabling to detect a large variety of biomolecules and bioparticles by their intrinsic charge. The review encompasses applications of BioFEDs for the label-free electrical detection of clinically relevant protein biomarkers, deoxyribonucleic acid molecules and viruses, enzyme-substrate reactions as well as recording of the cell acidification rate (as an indicator of cellular metabolism) and the extracellular potential.
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.