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Found 6289 publications

Estimation of sample size to forecast travel demand in urban public transport

Richard Horvath Balázs Horváth

Publication Name: 2015 International Conference on Models and Technologies for Intelligent Transportation Systems Mt ITS 2015

Publication Date: 2015-08-25

Volume: Unknown

Issue: Unknown

Page Range: 300-303

Description:

The starting point of a transport development project is knowledge on travel demand. If there is time and money for doing a detailed survey and passenger counting, we are able to build up detailed travel demand models. Usually this is not the case of the reality. Normally there is money and resources for some counting and maybe some surveying to clarify the demand data (e.g. OD matrix). There is always a discussion point; what is the needed size of the sample at a surveying, to be able to produce reliable data for OD matrix estimation. The paper deals with the issue of needed sample size and reliability of results.

Open Access: Yes

DOI: 10.1109/MTITS.2015.7223271

Development of individual information technology systems of experimental vehicles

Peter Dely István Lakatos Ernö Horváth Péter Kőrös

Publication Name: Saci 2015 10th Jubilee IEEE International Symposium on Applied Computational Intelligence and Informatics Proceedings

Publication Date: 2015-08-17

Volume: Unknown

Issue: Unknown

Page Range: 489-493

Description:

Two experimental vehicles were developed during the last two years in the Research Center of Vehicle Industry. The vehicles mentioned above are electrically driven and equipped with own developed computational modules. During development of the computational modules it was an important issue for us to create easily extendable systems which are easy-To-use. Different applications are realized in the two vehicles, consequently, different requirements were set up concerning our applications.

Open Access: Yes

DOI: 10.1109/SACI.2015.7208253

An abstraction of the Lidar measurements

Claudiu Radu Pozna Ernö Horváth Janos Kovacs

Publication Name: Saci 2015 10th Jubilee IEEE International Symposium on Applied Computational Intelligence and Informatics Proceedings

Publication Date: 2015-08-17

Volume: Unknown

Issue: Unknown

Page Range: 381-385

Description:

The laser scanner seems to be one of the favorite sensors used in mobile robots (autonomous car) localization. The Lidar is similar to the radar except radio signals are substituted with laser beams. Measurements are a collection of n lengths obtained for different firing angles. The paper presents an abstraction of this collection. The abstraction reduce the dimensions of data from n to 3 and can be used in obstacles avoiding or in localization. The paper presents the abstraction definition and a simulation scenario where the abstraction is used.

Open Access: Yes

DOI: 10.1109/SACI.2015.7208234

Estimation of the port number consumption of web browsing

Gábor Lencse

Publication Name: IEICE Transactions on Communications

Publication Date: 2015-08-01

Volume: E98B

Issue: 8

Page Range: 1580-1588

Description:

Due to the depletion of the public IPv4 address pool, Internet service providers will not be able to supply their new customers with public IPv4 addresses in the near future. Either they give private IPv4 addresses and use carrier grade NAT (CGN) or they move towards IPv6 and provide NAT64 service to the IPv6 only clients who want to reach IPv4 only servers. In both cases they must use a stateful NAT/NAT64 solution. When dimensioning a NAT/NAT64 gateway, the port number consumption of the clients is a key factor as the port numbers are 16 bits long and a unique one has to be provided for every session (when using traditional type NAPT, which does not include the destination IP address and port number in the tuple for the identification of TCP sessions) and a single web client may use several hundred sessions and an equal number of port numbers according to literature. In this paper, we present a method for the estimation of the port number consumption of web browsing. The method is based on the port number consumption measurements of the most popular web sites and their combination using the number of the visitors of the web sites as weight factors. We propose the resulting curve as an approximation of a general profile of the average port number consumption of web browsers after the first click, but without taking into consideration the effect of the web users' browsing behavior. We also discuss the case of the extended NAPT, which can reuse the source port numbers towards different destination IP addresses and/or destination port numbers. We propose a formula and give measurement results for the extended NAPT gateways, too. We disclose the measurement method in detail and provide the measurement scripts in Linux, too.

Open Access: Yes

DOI: 10.1587/transcom.E98.B.1580

Development of a land-use and transport interaction model as a part of a policy assessment framework for urban traffic calming

Mattias Juhász

Publication Name: Pollack Periodica

Publication Date: 2015-08-01

Volume: 10

Issue: 2

Page Range: 81-92

Description:

Initiation of traffic calming measures is on the challenging agenda of most cities, which are in pursuit of creating livable urban areas. However, previous studies on this research pointed out that the knowledge of the strategic aspects of application of these restrictions is insufficient, which is blocking further progression. Therefore a comprehensive policy assessment framework has been proposed and developed, which is combining modern modeling tools with reliable, well-tried appraisal methods. This work is another milestone of this broader research and its aim is to elaborate the modeling part of the framework enabling and establishing further works. The objective of this paper is to give an overview on this process and the result of which is a land-use and transport interaction model. In addition, it is also intended to practically test the model on a hypothetical case and to demonstrate its suitability.

Open Access: Yes

DOI: 10.1556/606.2015.10.2.8

On the absolute stability regions corresponding to partial sums of the exponential function

Tihamér A. Kocsis David I. Ketcheson Lajos Lóczi

Publication Name: IMA Journal of Numerical Analysis

Publication Date: 2015-07-01

Volume: 35

Issue: 3

Page Range: 1426-1455

Description:

Certain numerical methods for initial value problems have as stability function the nth partial sum of the exponential function. We study the stability region, that is, the set in the complex plane over which the nth partial sum has at most unit modulus. It is known that the asymptotic shape of the part of the stability region in the left half-plane is a semidisc. We quantify this by providing discs that enclose or are enclosed by the stability region or its left half-plane part. The radius of the smallest disc centred at the origin that contains the stability region (or its portion in the left half-plane) is determined for 1 ≤ n ≤ 20. Bounds on such radii are proved for n ≥ 2; these bounds are shown to be optimal in the limit n → +∞. We prove that the stability region and its complement, restricted to the imaginary axis, consist of alternating intervals of length tending to π, as n → ∞. Finally, we prove that a semidisc in the left half-plane centred at the origin and with vertical boundary lying on the imaginary axis is included in the stability region if and only if n ≡ 0 mod 4 or n ≡ 3 mod 4. The maximal radii of such semidiscs are exactly determined for 1 ≤ n ≤ 20.

Open Access: Yes

DOI: 10.1093/imanum/dru039

Steplength thresholds for invariance preserving of discretization methods of dynamical systems on a polyhedron

Yunfei Song Tamás Terlaky Zoltán Horváth

Publication Name: Discrete and Continuous Dynamical Systems Series A

Publication Date: 2015-07-01

Volume: 35

Issue: 7

Page Range: 2997-3013

Description:

Steplength thresholds for invariance preserving of three types of discretization methods on a polyhedron are considered. For Taylor approximation type discretization methods we prove that a valid steplength threshold can be obtained by finding the first positive zeros of a finite number of polynomial functions. Further, a simple and efficient algorithm is proposed to numerically compute the steplength threshold. For rational function type discretization methods we derive a valid steplength threshold for invariance preserving, which can be computed by using an analogous algorithm as in the first case. The relationship between the previous two types of discretization methods and the forward Euler method is studied. Finally, we show that, for the forward Euler method, the largest steplength threshold for invariance preserving can be computed by solving a finite number of linear optimization problems.

Open Access: Yes

DOI: 10.3934/dcds.2015.35.2997

Thermal simulations and measurements for rapid tool inserts in injection molding applications

Norbert Krisztián Kovács A. Suplicz J. G. Kovacs Tamás Tábi Béla Zink H. Hargitai Ferenc Szabó

Publication Name: Applied Thermal Engineering

Publication Date: 2015-06-25

Volume: 85

Issue: Unknown

Page Range: 44-51

Description:

apid prototyping (RP) is a widely used process in the industry to shorten development time. Another advantage of this technology is the ability to create conformal cooling systems, thus not only cooling time and cycle time can be shortened, but also shrinkage, thus warpage can be decreased. The main disadvantage of Rapid prototyping materials is their low thermal conductivity, which strongly influences cooling properties and warpage. The research based on a special developed injection mold for novel rapid prototyping based mold inserts with cooling systems. A method has been introduced to determine the most important thermal parameters for injection molding simulations using rapid tools. Those parameters, which can be measured such as the specific heat and thermal conductivity of the mold materials, are directly implemented into the software. The heat transfer coefficient between the polymer melt and the rapid tool insert surface cannot be measured in a reasonable way, thus simulation software was used to determine that based on indirect calculation derived from real measurements. In the paper, the method was proved with Fused Deposition Modeling (FDM) and Polyjet mold inserts.

Open Access: Yes

DOI: 10.1016/j.applthermaleng.2015.03.075

Two-Degree-of-Freedom Control Systems: The Youla Parameterization Approach

Csilla Bányász László Keviczky

Publication Name: Two Degree of Freedom Control Systems the Youla Parameterization Approach

Publication Date: 2015-06-18

Volume: Unknown

Issue: Unknown

Page Range: 1-514

Description:

This book covers the most important issues from classical and robust control, deterministic and stochastic control, system identification, and adaptive and iterative control strategies. It covers most of the known control system methodologies using a new base, the Youla parameterization (YP). This concept is introduced and extended for TDOF control loops. The Keviczky-Banyasz parameterization (KP) method developed for closed loop systems is also presented. The book is valuable for those who want to see through the jungle of available methods by using a unified approach, and for those who want to prepare computer code with a given algorithm. Provides comprehensive coverage of the most widely used control system methodologies. The first book to use the Youla parameterization (YP) as a common base for comparison and algorithm development. Compares YP and Keviczky-Banyasz (KB) parameterization to help you write your own computer algorithms.

Open Access: Yes

DOI: 10.1016/C2014-0-02908-5