Fakultät für Bauingenieurwesen und Geodäsie
https://www.repo.uni-hannover.de/handle/123456789/3
Frei zugängliche Publikationen aus der Fakultät für Bauingenieurwesen und Geodäsie2021-10-23T18:40:02ZEllipsoidal and Gaussian Kalman Filter Model for Discrete-Time Nonlinear Systems
https://www.repo.uni-hannover.de/handle/123456789/11398
Ellipsoidal and Gaussian Kalman Filter Model for Discrete-Time Nonlinear Systems
Sun, Ligang; Alkhatib, Hamza; Kargoll, Boris; Kreinovich, Vladik; Neumann, Ingo
In this paper, we propose a new technique—called Ellipsoidal and Gaussian Kalman filter—for state estimation of discrete-time nonlinear systems in situations when for some parts of uncertainty, we know the probability distributions, while for other parts of uncertainty, we only know the bounds (but we do not know the corresponding probabilities). Similarly to the usual Kalman filter, our algorithm is iterative: on each iteration, we first predict the state at the next moment of time, and then we use measurement results to correct the corresponding estimates. On each correction step, we solve a convex optimization problem to find the optimal estimate for the system’s state (and the optimal ellipsoid for describing the systems’s uncertainty). Testing our algorithm on several highly nonlinear problems has shown that the new algorithm performs the extended Kalman filter technique better—the state estimation technique usually applied to such nonlinear problems.
2019-01-01T00:00:00ZToward Optimality of Proper Generalised Decomposition Bases
https://www.repo.uni-hannover.de/handle/123456789/11397
Toward Optimality of Proper Generalised Decomposition Bases
Alameddin, Shadi; Fau, Amélie; Néron, David; Ladevèze, Pierre; Nackenhorst, Udo
The solution of structural problems with nonlinear material behaviour in a model order reduction framework is investigated in this paper. In such a framework, greedy algorithms or adaptive strategies are interesting as they adjust the reduced order basis (ROB) to the problem of interest. However, these greedy strategies may lead to an excessive increase in the size of the ROB, i.e., the solution is no more represented in its optimal low-dimensional expansion. Here, an optimised strategy is proposed to maintain, at each step of the greedy algorithm, the lowest dimension of a Proper Generalized Decomposition (PGD) basis using a randomised Singular Value Decomposition (SVD) algorithm. Comparing to conventional approaches such as Gram–Schmidt orthonormalisation or deterministic SVD, it is shown to be very efficient both in terms of numerical cost and optimality of the ROB. Examples with different mesh densities are investigated to demonstrate the numerical efficiency of the presented method.
2019-01-01T00:00:00ZMass variation observing system by high low
inter-satellite links (MOBILE) – a new concept for
sustained observation of mass transport from
space
https://www.repo.uni-hannover.de/handle/123456789/11317
Mass variation observing system by high low
inter-satellite links (MOBILE) – a new concept for
sustained observation of mass transport from
space
Pail, R.; Bamber, J.; Biancale, R.; Bingham, R.; Braitenberg, C.; Eicker, A.; Flechtner, F.; Gruber, T.; Güntner, A.; Heinzel, G.; Horwath, M.; Longuevergne, L.; Müller, J.; Panet, I.; Savenije, H.; Seneviratne, S.; Sneeuw, N.; van Dam, T.; Wouters, B.
As changes in gravity are directly related to mass
variability, satellite missions observing the Earth’s time
varying gravity eld are a unique tool for observing mass
transport processes in the Earth system, such as the water
cycle, rapid changes in the cryosphere, oceans, and
solid Earth processes, on a global scale. The observation
of Earth’s gravity eld was successfully performed by the
GRACE and GOCE satellite missions, and will be continued
by the GRACE Follow-On mission. A comprehensive
team of European scientists proposed the next-generation
gravity eld mission MOBILE in response to the European
Space Agency (ESA) call for a Core Mission in the
frame of Earth Explorer 10 (EE10). MOBILE is based on
the innovative observational concept of a high-low tracking
formation with micrometer ranging accuracy, complemented
by new instrument concepts. Since a high-low
tracking mission primarily observes the radial component
of gravity-induced orbit perturbations, the error structure
is close to isotropic. This geometry signi cantly reduces
artefacts of previous along-track ranging low-low formations
(GRACE, GRACE-Follow-On) such as the typical striping
patterns. The minimum con guration consists of at
least two medium-Earth orbiters (MEOs) at 10000 km altitude
or higher, and one low-Earth orbiter (LEO) at 350-
400 km. The main instrument is a laser-based distance or
distance change measurement system, which is placed at
the LEO. TheMEOs are equipped either with passive re ectors
or transponders. In a numerical closed-loop simulation,
itwas demonstrated that this minimum con guration
is in agreement with the threshold science requirements of
5 mm equivalent water height (EWH) accuracy at 400 km
wavelength, and 10 cm EWH at 200 km. MOBILE provides
promising potential future perspectives by linking the concept
to existing space infrastructure such as Galileo nextgeneration,
as future element of the Copernicus/Sentinel
programme, and holds the potential of miniaturization even up to swarm con gurations. As such MOBILE can be
considered as a precursor and role model for a sustained
mass transport observing system from space.
2019-01-01T00:00:00ZTraffic Regulator Detection and Identification from Crowdsourced Data—A Systematic Literature Review
https://www.repo.uni-hannover.de/handle/123456789/11312
Traffic Regulator Detection and Identification from Crowdsourced Data—A Systematic Literature Review
Zourlidou, Stefania; Sester, Monika
Mapping with surveying equipment is a time-consuming and cost-intensive procedure thatmakes the frequent map updating unaffordable. In the last few years, much research has focused oneliminating such problems by counting on crowdsourced data, such as GPS traces. An importantsource of information in maps, especially under the consideration of forthcoming self-driving vehicles,is the traffic regulators. This information is largely lacking in maps like OpenstreetMap (OSM) andthis article is motivated by this fact. The topic of this systematic literature review (SLR) is the detectionand recognition of traffic regulators such as traffic lights (signals), stop-, yield-, priority-signs, right ofway priority rules and turning restrictions at intersections, by leveraging non imagery crowdsourceddata. More particularly, the aim of this study is (1) to identify the range of detected and recognisedregulatory types bycrowdsensingmeans, (2) to indicate the different classification techniques thatcan be used for these two tasks, (3) to assess the performance of different methods, as well as (4)to identify important aspects of the applicability of these methods. The two largest databases ofpeer-reviewed literature were used to locate relevant research studies and after different screeningsteps eleven articles were selected for review. Two major findings were concluded—(a) most regulatortypes can be identified with over 80% accuracy, even using heuristic-driven approaches and (b) underthe current progress on the field, no study can be reproduced for comparative purposes nor can solelyrely on open data sources due to lack of publicly available datasets and ground truth maps. Futureresearch directions are highlighted as possible extensions of the reviewed studies.
2019-01-01T00:00:00Z