Browsing by Subject "000: Allgemeines, Wissenschaft"
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Research Data with files 3D Point Cloud of the Main Campus of Hamburg University of Technology (5 cm subsampled)(2023-03-22); ; ; ; Point cloud file (e57) of the main campus of Hamburg University of Technology containing intensity and color information for 125 separate scans.Data Type: Dataset213 163 - Some of the metrics are blocked by yourconsent settings
Research Data with files 4 Step Creation Method(2021-12-14); The 4 Step Creation Method is a method for systematic new development. It promotes creativity in interdisciplinary teams and provides a framework for cooperation so that original innovations can emerge. At the same time, the method can be used for the continuous improvement of existing systems.Data Type: Interactive Resource622 344 - Some of the metrics are blocked by yourconsent settings
Publication without files A circularly polarized antenna array with integrated calibration probes(2014-11); ; ; In this contribution internal calibration probes for circularly polarized patch antenna arrays are proposed. The probe network replicates the patch's natural mode of operation and thereby enables a precise calibration that incorporates finite array effects and mutual coupling. Furthermore, the approach allows for online monitoring which is of major importance for active arrays. The probes can be integrated with single feed circularly polarized microstrip antennas that use perturbations such as truncated corners. The feasibility of this calibration technique is demonstrated by measurements on a 4 by 1 array.Publicationtype: Conference PaperCitation Publisher Version:Asia-Pacific Microwave Conference (APMC 2014)49 - Some of the metrics are blocked by yourconsent settings
Publication without files A conditional time-varying multivariate latent growth curve model for the relationships between academics’ servant leadership behavior, affective commitment, and job performance during the Covid-19 pandemicIn our study, we investigated the change patterns in academics’ servant leadership behavior and affective commitment during and after the first Covid-19 lockdown (April 2020–August 2020) in Malaysia. Furthermore, we evaluated the influence of academics’ servant leadership behavior on job performance through affective commitment. We applied additional analyses to determine the degree to which the two former constructs are influenced by age and academic rank. To do so, we leveraged multivariate latent growth curve (LGC) modeling in analyzing the longitudinal data collected from 220 academics at three time points over a course of four months during the Covid-19 pandemic. Our results showed that, while servant leadership and affective commitment were stable over time, servant leadership was a driver of affective commitment and job performance. We also observed that affective commitment significantly mediated the relationship between academics’ servant leadership behavior and job performance. Moreover, we found interindividual differences in servant leadership and affective commitment in terms of age and academic rank at the beginning of the Covid-19 lockdown. Our multi-disciplinary research is among the limited number of studies applying a rigorous, longitudinal approach to examine behaviors (i.e., servant leadership and job performance) and attitudes (i.e., affective commitment) during the Covid-19 pandemic in higher education research.Publicationtype: Journal ArticleCitation Publisher Version:Quality & Quantity 57 (5): 4657-4680 (2023-08)Publisher DOI:10.1007/s11135-022-01568-627 - Some of the metrics are blocked by yourconsent settings
Publication with files A consequential assessment of changes in greenhouse gas emissions due to the introduction of wheat straw ethanol in the context of European legislationUntil today, first generation (1G) biofuels dominate the market for alternative fuels. The European Commission decided to cap 1G biofuels and promote second generation (2G) biofuels with the intention to reduce greenhouse gas (GHG) emissions, to limit the competition of food, feed and biofuels, as well as to improve societal approval. The assessment of consequences entailed to a shift from 1G to 2G biofuels is required to judge whether such a shift is advisable or not. According to the renewable energy directive (RED), GHG savings, need to be determined for all biofuels. By the end of 2020, fuel blends need to achieve a GHG reduction of 6%. Thus, GHG savings will determine the quantity of biofuel to be blended with fossil fuels and thereby eventually define the demand for biofuels. In this paper, the consequences of a shift from a 1G to a 2G biofuel is assessed by the example of bioethanol from wheat grains and straw. In total, three concepts of 2G ethanol production from wheat straw are considered: fermentation of C6-sugars with (1) co-production of feed, (2) coupled with biogas production and (3) co-fermentation of C5- and C6-sugars with co-production of feed. To determine the effect of the introduction of 2G ethanol, GHG savings according to RED are calculated first, and, in a second step, consequences of the shift from 1G to 2G ethanol are assessed by accounting for substitution mechanisms and emissions from direct and indirect land-use change (LUC). GHG savings of these 2G concepts according to RED methodology range from 103 to 105%. The shift from 1G ethanol to these 2G concepts is assessed by two scenarios: (1) additional production of 2G ethanol and (2) the replacement of 1G ethanol by 2G ethanol. Results indicate that GHG emissions decrease in scenario 1 if all surplus ethanol replaces fossil fuels. Under the given assumptions, the reduction in emissions ranges from 9.0 to 12.1 kg CO2-eq./GJ ethanol-gasoline blend. If 1G ethanol is replaced by 2G ethanol, GHG emission increase in a range from 7.5 to 16.5 kg CO2-eq./GJ fuel blend. This is mainly due to the provision of feed that needs to be supplied as a consequence of the shift in production: 1G ethanol production provides a high protein feed that needs to be provided by other means. Hence, the main driver for an increase in emissions is the provision of soybean meal and entailed emissions from LUC. A sensitivity analysis shows that these results are robust regarding input parameters and LUC assumptions. These findings point out that it is of utmost importance to assess changes induced by the introduction of novel fuels rather than assessing them isolated from market conditions. Based on these findings, it can be concluded that current and proposed legislation might trigger effects opposed to those intended.Publicationtype: Journal ArticleTORE-DOI:10.15480/882.2404Citation Publisher Version:Applied Energy (211): 368-381 (2018-02-01)Publisher DOI:10.1016/j.apenergy.2017.10.105Scopus© Citations 16 298 582 - Some of the metrics are blocked by yourconsent settings
Publication without files A demand response approach locally implementable for waterbedsThis paper presents a demand response scheme for waterbeds that can be implemented with currently available infrastructure. It balances the requirements of saving energy and shifting power to times with higher power availability by scheduling heating phases such that costs according to an electricity exchange's virtual electricity tariff are minimized. The approach was successfully validated with a real waterbed under real conditions.Publicationtype: Conference PaperCitation Publisher Version:International Conference on Networked Systems, NetSys : 7089088 (2015-04-15)Publisher DOI:10.1109/NetSys.2015.7089088110 - Some of the metrics are blocked by yourconsent settings
Publication without files A detailed spatial analysis of motorization in the urban realm - minimum parking requirements and mobility concepts for housing(2019-03-06)Publicationtype: Conference PresentationCitation Publisher Version:Annual Meeting of the American Association of Geographers, AAG: (2019-04-06)107 - Some of the metrics are blocked by yourconsent settings
Publication without files A four-port network compensation approach for directional couplers(2011-10) ;Müller, JohannesA novel approach for compensating the phase velocity difference in coupled line structures is presented. It utilizes twofold symmetric four-port networks. Analytical design equations are derived. The method is shown to be superior to other lumped element compensation techniques. The advantages are the simple and straightforward design procedure and the inherently broadband compensation. A realized microstrip coupler exhibits good measured performance, thus confirming the approach.Publicationtype: Conference PaperCitation Publisher Version:European Microwave Conference (EuMC 2012)33 - Some of the metrics are blocked by yourconsent settings
Publication without files A Fully Differential Ultra-Broadband Power Divider with Integrated Resistors(2019-10) ;Deutschmann, Björn; A fully differential power divider with ultra-broadband performance is presented. It consists of multi-section Wilkinson power combiners vertically aligned in a multilayer circuit board, which are fed by differential via transitions. The carbon paste decoupling resistors are integrated in the stack. The measured differential-mode output isolation exceeds 10 dB above 2.9 GHz. The excess insertion loss remains below 1.0 dB up to 21 GHz and reaches 2.0 dB at 36.5 GHz. The structure, which is designed for compactness, occupies only 50 mm2 .Publicationtype: Conference PaperCitation Publisher Version:European Microwave Conference (EuMC): 121-124 (2019-10)Publisher DOI:10.23919/EuMC.2019.8910953360 - Some of the metrics are blocked by yourconsent settings
Publication without files A metrological and application-related comparison of six consumer grade stereo depth cameras for the use in robotics(2022-11); ;Herzfeld, Jonas; ; Consumer grade depth cameras are important devices to enable robots and unmanned vehicles to perceive their environments. Three major technologies are relevant for those devices: Time-of-Flight, structured light and stereo vision. Stereo cameras in particular have conquered the market in recent years, with Intel's D-series systems leading the way. Besides stereo cameras from Intel, there are many models from other manufacturers, but it has not yet been investigated how these cameras perform in comparison. This paper proposes and applies methods to measure the performance of depth cameras in a metrological way as well as with a focus on the use in robotics. Six stereo depth cameras are tested and compared. In addition, a real world benchmark test and a qualitative evaluation of the accompanying software and documentation is done. A clear recommendation is given in the end.Publicationtype: Conference PaperCitation Publisher Version:IEEE International Symposium on Robotic and Sensors Environments (ROSE 2022)Publisher DOI:10.1109/ROSE56499.2022.9977421100 - Some of the metrics are blocked by yourconsent settings
Publication without files A new criterion for assessing discriminant validity in variance-based structural equation modeling(2014-08-22); ; Discriminant validity assessment has become a generally accepted prerequisite for analyzing relationships between latent variables. For variance-based structural equation modeling, such as partial least squares, the Fornell-Larcker criterion and the examination of cross-loadings are the dominant approaches for evaluating discriminant validity. By means of a simulation study, we show that these approaches do not reliably detect the lack of discriminant validity in common research situations. We therefore propose an alternative approach, based on the multitrait-multimethod matrix, to assess discriminant validity: the heterotrait-monotrait ratio of correlations. We demonstrate its superior performance by means of a Monte Carlo simulation study, in which we compare the new approach to the Fornell-Larcker criterion and the assessment of (partial) cross-loadings. Finally, we provide guidelines on how to handle discriminant validity issues in variance-based structural equation modeling.Publicationtype: Journal ArticleCitation Publisher Version:Journal of the Academy of Marketing Science 43 (1): 115-135 (2014-08-22)Publisher DOI:10.1007/s11747-014-0403-8155 - Some of the metrics are blocked by yourconsent settings
Publication with files A note on reciprocity and modified dictator gamesThis note presents results from modified dictator games in which the payoff-relevant game is either chosen randomly or by the recipients. We do not observe reciprocal behavior when recipients choose the game: Dictators do not condition their donations on the game chosen by recipients.Publicationtype: Journal ArticleTORE-DOI:10.15480/882.4674Citation Publisher Version:Economics Letters 121 (2): 202-205 (2013-11)Publisher DOI:10.1016/j.econlet.2013.08.004Scopus© Citations 1 69 215 - Some of the metrics are blocked by yourconsent settings
Publication without files A partitioned solution approach for the simulation of the dynamic behaviour of flexible marine propellers(2020-01-02); ; ; Modern designs of ship-propellers make use of novel materials such as composites, which may show a much lower stiffness than classical material. In order to accurately predict the hydrodynamic characteristics of these propellers in real operating conditions, the structural deformation must be accounted for, which leads to a fluid-structure interaction problem. In the present paper, a partitioned solution approach for such a strongly coupled two-field problem is presented. Owing to the separate modelling of the fluid and the structural problem in such approaches, specialised numerical methods can be applied on either side. Thanks to their superior convergence properties, we use high-order finite elements to discretise the structural problem. On the fluid side, a boundary element method, which is specifically designed to simulate the hydrodynamic behaviour of ship propellers is employed. In order to stabilise the solution procedure, different coupling algorithms and convergence acceleration methods are investigated.Publicationtype: Journal ArticleCitation Publisher Version:Ship Technology Research 1 (67): 37-50 (2020-01-02)Publisher DOI:10.1080/09377255.2018.154278271 - Some of the metrics are blocked by yourconsent settings
Publication without files A review of fatigue test data on weld toe grinding and weld profilingThe aim of this paper is to investigate the effects of weld toe grinding and weld profiling on the fatigue strength of welded joints and the main influencing factors. Thus, experimental test results of welds improved by different grinding techniques are reviewed. In total, 445 small- and full-scale fatigue test results of various weld types and steel grades with yield strengths up to 1100 MPa are analysed. The obtained improvements of two FAT classes correspond well with current guidelines; however, a new S–N curve slope of m = 4 is recommended—in line with proposals for other weld geometry improvement techniques.Publicationtype: Journal ArticleCitation Publisher Version:International Journal of Fatigue 145: 106073 (2021-04)Publisher DOI:10.1016/j.ijfatigue.2020.10607378 - Some of the metrics are blocked by yourconsent settings
Publication without files A Review of Terra Preta Sanitation with a Focus on the Research Outcomes of the Institute of Wastewater Management and Water Protection (AWW)(2018-01); Schaldach, RuthTerra Preta Sanitation (TPS) is an astonishing biowaste/sanitation system from a highly advanced ancient culture. It shows great potential for soil building and nutrient recycling from excreta. TPS was and is developed based on a rediscovered historic practice. TPS systems treat excreta and produce valuable soil amendments. Such sanitation systems can contribute to attaining particular Sustainable Development Goals. Findings of highly fertile soils in the Amazon region initiated research in this field of study. Archaeological research revealed that Terra Preta was produced from biowaste and excreta with charcoal additives and layers of pieces from broken ceramic. The Institute of Wastewater Management and Water Protection (AWW) at Hamburg University of Technology (TUHH) conducted research on lactic acid fermentation (LAF) and vermicomposting, with a special focus on sanitisation and process conditions. The AWW performed case studies in India, the Philippines and Ethiopia and developed implementation strategies for conventional and new sanitation systems. Moreover, the Institute facilitated the design of a container toilet for Terra Preta Sanitation, which is adjusted to different cultural requirements. LAF can make the collection over longer timespans odour free and sanitised at the same time. The downside is a demand for a sugar additive, however, this can be solved by the addition of biowaste. This literature review gives an overview of the current state of research conducted at the Institute of Wastewater Management and Water Protection (AWW) at the Hamburg University of Technology.Publicationtype: Journal ArticleCitation Publisher Version:RUVIVAL publication series 3: 19-26 (2018-01)191 - Some of the metrics are blocked by yourconsent settings
Publication without files A smart jamming system for UMTS/WCDMA cellular phone networks for search and rescue applications(2012-06); ; ; ; ; Recent statistics show an increase in environmental disasters, a fact which is also perceivable to the public as reports of avalanches, earthquakes and landslides mount in media coverage. This paper introduces one part of the I-LOV project, endorsed by the German Federal Ministry of Education and Research. In this project partners from relief organizations, universities and industry investigate enhancements to disaster handling and victim rescue. One possible option is to take advantage of the fact, that a lot of people own a mobile phone today. To locate a person by his or her mobile phone requires to take over the phone by an own Base Transceiver Station (BTS). Jamming all other networks is one option to achieve that. This paper will introduce a new Field Programmable Gate Array (FPGA) based jamming system which disturbs only the absolute necessary parts of the WCDMA spectrum but reliably cuts all connections between mobile stations (MS) and existing BTS. The whole system including the signal generator and the front end will be discussed. Also measurement results will be shown.Publicationtype: Conference PaperCitation Publisher Version:IEEE MTT-S International Microwave Symposium Digest: 6257769 (2012-06)Publisher DOI:10.1109/MWSYM.2012.625776969 - Some of the metrics are blocked by yourconsent settings
Publication without files Ach, so ist das? 50 Alltagsphänomene neugierig hinterfragtVerständliche, anschauliche Erläuterungen von 50 Alltagsphänomenen aus Fluidmechanik und Thermodynamik für technisch interessierte Laien. Mit Zeichnungen und einem Glossar.Publicationtype: Book81 - Some of the metrics are blocked by yourconsent settings
Publication without files ACTOR: Accelerating Fault Injection Campaigns Using Timeout Detection Based on Autocorrelation(2022-09); ; ; Fault-injection (FI) campaigns provide an in-depth resilience analysis of safety-critical systems in the presence of transient hardware faults. However, FI campaigns require many independent injection experiments and, combined, long run times, especially if we aim for a high coverage of the fault space. Besides reducing the number of pilot injections (e.g., with def-use pruning) in the first place, we can also speed up the overall campaign by speeding up individual experiments. From our experiments, we see that the timeout failure class is especially important here: Although timeouts account only for 8% (QSort) of the injections, they require 32% of the campaign run time. In this paper, we analyze and discuss the nature of timeouts as a failure class, and reason about the general design of dynamic timeout detectors. Based on those insights, we propose ACTOR, a method to identify and abort stuck experiments early by performing autocorrelation on the branch-target history. Applied to seven MiBench benchmarks, we can reduce the number of executed post-injection instructions by up to 30%, which translates into an end-to-end saving of 27%. Thereby, the absolute classification error of experiments as timeouts was always less than 0.5%.Publicationtype: Conference PaperCitation Publisher Version:International Conference on Computer Safety, Reliability, and Security (SAFECOMP 2022)Publisher DOI:10.1007/978-3-031-14835-4_1731 - Some of the metrics are blocked by yourconsent settings
Publication with files Added value of coreference annotation for character analysis in narratives(2018); A central question for the analysis of literary texts in digital humanities is the identification of characters in the text. A simple approach would be to reduce the analysis to mentions of the character by its proper name as these are easy to retrieve. A more elaborate solution requires coreference annotation, identifying all mentions of a character in the text, irrespective of their form. Using the example of the novel Corpus Delicti by the German author Juli Zeh, we compare these two approaches and show the added value of coreference annotation.Publicationtype: Conference PaperTORE-DOI:10.15480/882.2596Citation Publisher Version:Workshop on Annotation in Digital Humanities (annDH 2018)Scopus© Citations 1 281 164 - Some of the metrics are blocked by yourconsent settings
Publication without files Adjoint Complement to the Volume-of-Fluid Method for Immiscible Flows(2021-09-01); ; ; ; The paper is concerned with an adjoint complement to the Volume-of-Fluid (VoF) method for immiscible two-phase flows, e.g. air and water, which is widely used in marine engineering due to its computational efficiency. The particular challenge of the primal and the corresponding adjoint VoF-approach refers to the sharp interface treatment featuring discontinuous physical properties. Both the continuous adjoint two-phase system (integration-by-parts) and the corresponding dual compressive convection schemes (summation-by-parts) are derived for two prominent compressive convection schemes, namely the High Resolution Interface Capturing Scheme (HRIC) and Compressive Interface Capturing Scheme for Arbitrary Meshes (CICSAM). The dual scheme rigorously mirrors the primal Normalized-Variable-Diagram (NVD) stencils. Attention is restricted to steady state applications. Thus both the primal and the dual procedures are performed in pseudo time and the backward integration of the dual approach is performed around the (pseudo-temporal) converged primal field. The paper analyses the primal and adjoint equations for an engineering model problem. An analytical solution to the model problem is initially presented, which displays that the adjoint part does not offer a unique, non-trivial solution. As a remedy, an additional diffusive concentration term is introduced to the adjoint concentration equation. Numerical results obtained from the modified approach are benchmarked against the analytical solution for the model problem. Supplementary, the influence of the modification on the sensitivities obtained from simulations for the two-dimensional flow around a submerged hydrofoil are discussed. The final application refers to a shape-optimization of a generic 3D underwater vehicle and underlines a negligible influence of the free mobility parameter.Publicationtype: Journal ArticleCitation Publisher Version:Journal of computational physics 444: 110411 (2021-09-01)Publisher DOI:10.1016/j.jcp.2021.11041198