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Found 6423 publications

Computation of sensitivity of periodically excited dynamical systems

Mate Antali Zoltán Horváth

Publication Name: Journal of Engineering Mathematics

Publication Date: 2018-12-01

Volume: 113

Issue: 1

Page Range: 123-142

Description:

In the optimization of continuous-time dynamical systems, it can be important to numerically calculate the parametric sensitivity of some long-time-averaged quantities in the system. These computations are challenging for typical numerical methods in the presence of oscillations, which can originate from the internal structure of an autonomous dynamical system or be caused by an external periodic excitation. The case of periodic excitation is motivated by the problem of heat conduction in mechanical parts in engines, where the mean strength of the heat fluctuation can be an important parameter in the engineering design. In this work, approaches to transform periodically excited systems into autonomous systems appropriate for sensitivity analysis were investigated. The least-squares shadowing method is used to compute the sensitivities, and the effect of different kinds of transformation compared. The resulting numerical method is presented using the motivating example of heat conduction.

Open Access: Yes

DOI: 10.1007/s10665-018-9977-3

We remember Vilmos Schulhof (1874-1944)

Ágota Kulisch Noémi Gyarmati Zsuzsanna Mándó József Horváth Ágota Kránicz Annamária Bergmann Szilvia Boros

Publication Name: Orvosi Hetilap

Publication Date: 2024-11-17

Volume: 165

Issue: 46

Page Range: 1837-1839

Description:

No description provided

Open Access: Yes

DOI: 10.1556/650.2024.HO2805

Invariance Preserving Discretization Methods of Dynamical Systems

Yunfei Song Tamás Terlaky Zoltán Horváth

Publication Name: Vietnam Journal of Mathematics

Publication Date: 2018-12-01

Volume: 46

Issue: 4

Page Range: 803-823

Description:

In this paper, we consider local and uniform invariance preserving steplength thresholds on a set when a discretization method is applied to a linear or nonlinear dynamical system. For the forward or backward Euler method, the existence of local and uniform invariance preserving steplength thresholds is proven when the invariant sets are polyhedra, ellipsoids, or Lorenz cones. Further, we also quantify the steplength thresholds of the backward Euler methods on these sets for linear dynamical systems. Finally, we present our main results on the existence of uniform invariance preserving steplength threshold of general discretization methods on general convex sets, compact sets, and proper cones both for linear and nonlinear dynamical systems.

Open Access: Yes

DOI: 10.1007/s10013-018-0305-z

Comparison of Italian and Hungarian Black Spot Ranking

Dániel Miletics Attila Borsos Salvatore Cafiso C. D'Agostino

Publication Name: Transportation Research Procedia

Publication Date: 2016-01-01

Volume: 14

Issue: Unknown

Page Range: 2148-2157

Description:

Black spot ranking is an important tool for finding the sites with potential safety improvement on the road network. The EU Directive on Road Infrastructure Safety Management also demands the ranking of high accident concentration sites. This paper gives an introduction to localizing high accident concentration sites and the indicators used by Italy and Hungary. Accident and traffic volume data are gathered for motorway sections from both countries. Safety ranking is made using two conventional indicators, absolute number of accidents and accident rate. A more sophisticated ranking using the Empirical Bayes method is applied. Expected average crash frequency with Empirical Bayes adjustment is calculated. Based on the estimation of the crash frequency, the Critical Crash Rate (CCR) was added to identify and rank black spots. This additional performance measure is able to take into account traffic volume as required by the EU Directive. Results of the Empirical Bayes method are compared with the conventional procedures. It is concluded that the results are not comparable; inasmuch as there are modifications in the order of black spots. Based on the comparison of results recommendations are given to change the practice in both countries.

Open Access: Yes

DOI: 10.1016/j.trpro.2016.05.230

Controlled bidirectional energy transfer by ultracapacitors in electric drive

Z. Puklus András Fehér

Publication Name: 12th IEEE International Symposium on Computational Intelligence and Informatics Cinti 2011 Proceedings

Publication Date: 2011-12-01

Volume: Unknown

Issue: Unknown

Page Range: 31-34

Description:

This paper shows the possibility of the two-directional energy transfer between energy sources using the example of ultracapacitors. The showed method allows bidirectional energy transfer between power systems which use different voltage levels. We used PSIM program to simulate the bidirectional energy transfer and study the operation of the applied model. © 2011 IEEE.

Open Access: Yes

DOI: 10.1109/CINTI.2011.6108526

Adaptive improvement of a passive antilock brake control

J. O. Pedro S. John Laszlo T. Koczy

Publication Name: IEEE AFRICON Conference

Publication Date: 2011-12-12

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The use of reliable or at least realistic friction models is a key factor in simulation studies related to antilock brake control systems. In the literature a plethora of strongly nonlinear tyre-road friction models are available. Certain models have singular expressions in the arguments of exponential terms in the vicinity of zero car body velocity though this region has practical significance. Since the parameters of these singular models may quickly vary in time with the variation of the road conditions their realtime identification was evaded in a paper that applied a simple observer instead. This method has been improved in the present paper by applying a novel adaptive technique for compensating the effects of the imprecisely known other (i.e. not related to the tyre-road friction) parameters. By the use of a particular friction model it was found via simulations that the adaptive technique can considerably shorten the braking distance. © 2011 IEEE.

Open Access: Yes

DOI: 10.1109/AFRCON.2011.6072040

“So, I told him to look for friends!” Barriers and protecting factors that may facilitate inclusion for children with Language Disorder in everyday social settings: Cross-cultural qualitative interviews with parents

Isabel R. Rodriguez-Ortiz Sam Harding Rena Lyons Maja Kelić Kristine M. Jensen de López Inge S. Klatte Julie Feilberg Sofia Baena Tina C. Mantel Thora S. Ulfsdottir Rama Novogrodsky Krisztina Zajdó

Publication Name: Research in Developmental Disabilities

Publication Date: 2021-08-01

Volume: 115

Issue: Unknown

Page Range: Unknown

Description:

Purpose: Although researchers have explored parental perspectives on childhood speech and language disorders, this work has mostly been conducted in English-speaking countries. Little is known about parental experiences across countries. Participation in the COST Action IS1406 ‘Enhancing children's oral language skills across Europe and beyond’ provided an opportunity to conduct cross-cultural qualitative interviews. The aims were to explore how parents construe inclusion and/or exclusion of their child and how parents involve themselves in order to facilitate inclusion. Method: Parents from nine countries and with a child who had received services for speech-language disorder participated in semi-structured qualitative interviews. We used thematic analysis to analyze the data. Results: Two overarching themes were identified: ‘Language disabilities led to social exclusion’ and ‘Promoting pathways to social inclusion’. Two subthemes were identified Interpersonal relationships are important and Deliberate proactiveness as stepping stones for social inclusion. Conclusions: Across countries, parents report that their children's hidden disability causes misunderstandings that can lead to social exclusion and that they are important advocates for their children. It is important that the voices and experiences of parents of children with developmental disabilities are understood and acknowledged. Parents’ recommendations about how to support social inclusion need to be addressed at all levels of society.

Open Access: Yes

DOI: 10.1016/j.ridd.2021.103963

Human-Centric Automation and Optimization for Smart Homes

János Botzheim Noel Nuo Wi Tay Naoyuki Kubota

Publication Name: IEEE Transactions on Automation Science and Engineering

Publication Date: 2018-10-01

Volume: 15

Issue: 4

Page Range: 1759-1771

Description:

A smart home needs to be human-centric, where it tries to fulfill human needs given the devices it has. Various works are developed to provide homes with reasoning and planning capability to fulfill goals, but most do not support complex sequence of plans or require significant manual effort in devising subplans. This is further aggravated by the need to optimize conflicting personal goals. A solution is to solve the planning problem represented as constraint satisfaction problem (CSP). But CSP uses hard constraints and, thus, cannot handle optimization and partial goal fulfillment efficiently. This paper aims to extend this approach to weighted CSP. Knowledge representation to help in generating planning rules is also proposed, as well as methods to improve performances. Case studies show that the system can provide intelligent and complex plans from activities generated from semantic annotations of the devices, as well as optimization to maximize personal constraints' fulfillment. Note to Practitioners - Smart home should maximize the fulfillment of personal goals that are often conflicting. For example, it should try to fulfill as much as possible the requests made by both the mother and daughter who wants to watch TV but both having different channel preferences. That said, every person has a set of goals or constraints that they hope the smart home can fulfill. Therefore, human-centric system that automates the loosely coupled devices of the smart home to optimize the goals or constraints of individuals in the home is developed. Automated planning is done using converted services extracted from devices, where conversion is done using existing tools and concepts from Web technologies. Weighted constraint satisfaction that provides the declarative approach to cover large problem domain to realize the automated planner with optimization capability is proposed. Details to speed up planning through search space reduction are also given. Real-time case studies are run in a prototype smart home to demonstrate its applicability and intelligence, where every planning is performed under a maximum of 10 s. The vision of this paper is to be able to implement such system in a community, where devices everywhere can cooperate to ensure the well-being of the community.

Open Access: Yes

DOI: 10.1109/TASE.2018.2789658

Sustainable travel to school programs in Hungary Role of Pedibus and Bicibus pilot programs today

Petra Kinga Kézai

Publication Name: Civil Szemle

Publication Date: 2024-03-21

Volume: 21

Issue: 1

Page Range: 71-88

Description:

In the context of modern urban development, various socio-technical innovations have proliferated in response to urban challenges, offering well-defined solutions. Since the 1970s, the so-called ‚backseat generation’, a group of children whose parents drive them to school every day, has emerged in developed countries, particularly in urban areas. This phenomenon has many negative effects on children, the environment and urban spaces. The present study addresses the issue of urban transport management, in particular the issue of daily school transport. It aims to present, based on literature analysis, good international examples, such as the pedibus and the bicycle bus, which emphasise local values and resources in the light of the ‚slow city’ concept. The study concludes with a presentation and evaluation of the pilot programmes (Pedibus in Gödöllő and Bicibus in Pécs) that have also become established in Hungary in recent years. These programmes offer a supervised, safe, group-based solution for school children and their families to go to school, and build community between different generations.

Open Access: Yes

DOI: 10.62560/csz.2024.01.05