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Found 6412 publications

Methodology for DNS cache poisoning vulnerability analysis of DNS64 implementations

G. Lencse Y. Kadobayashi

Publication Name: Infocommunications Journal

Publication Date: 2018-06-01

Volume: 10

Issue: 2

Page Range: 13-25

Description:

The trustworthy operation of the DNS service is a very important precondition for a secure Internet. As we point it out, DNS cache poisoning could be even more dangerous if it is performed against DNS64 servers. Based on RFC 5452, we give an introduction to the three main components of DNS cache poisoning vulnerability, namely Transaction ID prediction, source port number prediction, and a birthday paradox based attack, which is possible if a DNS or DNS64 server sends out multiple equivalent queries (with identical QNAME, QTYPE, and QCLASS fields) concurrently. We design and implement a methodology and a testbed, which can be used for the systematic testing of DNS or DNS64 implementations, whether they are susceptible to these three vulnerabilities. We perform the tests with the following DNS64 implementations: BIND, PowerDNS, Unbound, TOTD (two versions) and mtd64-ng. As for the testbed, we use three virtual Linux machines executed by a Windows 7 host. As for tools, we use VMware Workstation 12 Player for virtualization, Wireshark and tshark for monitoring, dns64perf for Transaction ID and source port predictability tests, and our currently developed “birthday-test” program for concurrently sent multiple equivalent queries testing. Our methodology can be used for DNS cache poisoning vulnerability analysis of further DNS or DNS64 implementations. A testbed with the same structure may be used for security vulnerability analysis of DNS or DNS64 servers and also NAT64 gateways concerning further threats.

Open Access: Yes

DOI: DOI not available

Linear-Matrix-Inequality-Based Controller and Observer Design for Induction Machine

Miklós Kuczmann Zoltan Nemeth

Publication Name: Electronics Switzerland

Publication Date: 2022-12-01

Volume: 11

Issue: 23

Page Range: Unknown

Description:

The modeling and drive control of electric machines are still actively researched scientific topics. Most of the existing models contain parameters that have no physical content or cannot be measured at all. For this reason, the use of observers in modern drive control algorithms is necessary. The main goal of this paper is to present the mathematical formalism of a linear matrix inequality (LMI)-based controller-observer design for a tensor product (TP) transformation-based model, including its implementation in a simulation environment. Based solely upon simulation results, the designed observer can provide a stable and accurate state space variable, regardless of the highly nonlinear induction machine model.

Open Access: Yes

DOI: 10.3390/electronics11233894

Linearly priced timed automata for the bus schedule assignment problem

Máté Hegyháti Balazs David Miklos Kresz

Publication Name: Proceedings Gol 2018 4th IEEE International Conference on Logistics Operations Management

Publication Date: 2018-06-08

Volume: Unknown

Issue: Unknown

Page Range: 1-7

Description:

Papers dealing with optimization problems in public transportation usually follow the same methodology. The problem is modeled in a classical mathematical way, and then either solved directly using mathematical programming methods, or by the application of combinatorial heuristics. Even if this process yields an optimal solution, it might prove complicated to apply the achieved results directly in practice. In a transportation system, solutions for individual problems are only part of a more complex process, and they are often used only to aid experts in making decisions. However, the structure of the problem and the steps taken to achieve the solution are often lost in the solution process, while they might prove extremely useful to a human planner. This paper introduces a linearly priced timed automata model for the bus schedule assignment problem. With its help, the steps taken to achieve any feasible solution of the problem can be easily reconstructed, providing another tool for human experts to use in their decision planning process.

Open Access: Yes

DOI: 10.1109/GOL.2018.8378104

FEM-Based Power Transformer Model for Superconducting and Conventional Power Transformer Optimization

Tamas Orosz

Publication Name: Energies

Publication Date: 2022-09-01

Volume: 15

Issue: 17

Page Range: Unknown

Description:

There were many promising superconducting materials discovered in the last decades that can significantly increase the efficiency of large power transformers. However, these large machines are generally custom-made and tailored to the given application. During the design process the most economical design should be selected from thousands of applicable solutions in a short design period. Due to the nonlinearity of the task, the cost-optimal transformer design, which has the smallest costs during the transformers’ planned lifetime, is usually not the design with the highest efficiency. Due to the topic’s importance, many simplified transformer models were published in the literature to resolve this problem. However, only a few papers considered this preliminary design optimization problem in the case of superconducting transformers and none of them made a comparison with a validated conventional transformer optimization model. This paper proposes a novel FEM-based two-winding transformer model, which can be used to calculate the main dimension of conventional and superconducting transformer designs. The models are stored in a unified JSON-file format, which can be easily integrated into an evolutionary or genetic algorithm-based optimization. The paper shows the used methods and their accuracy on conventional 10 MVA and superconducting 1.2 MVA transformer designs. Moreover, a simple cost optimization with the 10 MVA transformer was performed for two realistic economic scenarios. The results show that in some cases the cheaper, but less efficient, transformer can be the more economic.

Open Access: Yes

DOI: 10.3390/en15176177

Tribological Properties of Nano-Sized ZrO2 Ceramic Particles in Automotive Lubricants

Rajmund Kuti D. Tóth I. Szabó

Publication Name: Fme Transactions

Publication Date: 2021-01-01

Volume: 49

Issue: 1

Page Range: 36-43

Description:

The demand for decreasing CO2-emission and harmful material content of the exhaust gas of passenger cars requires the improvement of the entire powertrain including the applied lubricants. One of the possible future engines lubricant can be the nano-sized ceramic particles, which can provide positive tribological properties also in the presence of nonmetallic surface materials. This paper presents the experimental investigation of ZrO2 nanoceramic powder as a lubricant additive. The tribological performance of the lubricant samples was experimentally investigated on a ball-on-disc translation tribometer. An optimum concentration was found at 0.4 wt%, where the wear scar diameter on the ball specimen was reduced by more than 40% compared to the reference sample. The SEM-analysis confirmed the mending mechanism theory: nanoparticles were revealed to aggregate between the asperities resulting in a significantly smoother contact surface.

Open Access: Yes

DOI: 10.5937/FME2101036T

Performance analysis and comparison of different DNS64 implementations for Linux, OpenBSD and FreeBSD

Sandor R. Repas G. Lencse

Publication Name: Proceedings International Conference on Advanced Information Networking and Applications AINA

Publication Date: 2013-08-08

Volume: Unknown

Issue: Unknown

Page Range: 877-884

Description:

The transition mechanisms for the first phase of IPv6 deployment are surveyed and the most important DNS64 solutions are selected. The test environment and the testing method are described. As for the selected DNS64 implementations, the performance of both BIND9 and TOTD running under Linux, OpenBSD and FreeBSD are measured and compared. The stability of all the tested DNS64 solutions was analyzed under serious overload conditions to test if they may be used in production environments with strong response time requirements. © 2013 IEEE.

Open Access: Yes

DOI: 10.1109/AINA.2013.80

Explaining variability in the production of seed and allergenic pollen by invasive Ambrosia artemisiifolia across Europe

Zita Dorner Huseyin Onen Danijela Stešević Gerhard Karrer Guillaume Fried Paulina Anastasiu Annamária Fenesi Robert Leskovšek Maja Šćepanović Cristina Preda Viktor Tiborcz Caspar A. Hallmann Gergely Zagyvai Bruno Chauvel G. Pinke Eelke Jongejans Mihály Zalai Alla Aleksanyan K. Nagy Andreas Lemke Levani Kalatozishvili Melinda Leitsch-Vitalos Barbara Tokarska-Guzik Gabriella Kazinczi Heinz Müller-Schärer Peter Tóth Suzanne T.E. Lommen

Publication Name: Biological Invasions

Publication Date: 2018-06-01

Volume: 20

Issue: 6

Page Range: 1475-1491

Description:

To better manage invasive populations, it is vital to understand the environmental drivers underlying spatial variation in demographic performance of invasive individuals and populations. The invasive common ragweed, Ambrosia artemisiifolia, has severe adverse effects on agriculture and human health, due to its vast production of seeds and allergenic pollen. Here, we identify the scale and nature of environmental factors driving individual performance of A. artemisiifolia, and assess their relative importance. We studied 39 populations across the European continent, covering different climatic and habitat conditions. We found that plant size is the most important determinant in variation of per-capita seed and pollen production. Using plant volume as a measure of individual performance, we found that the local environment (i.e. the site) is far more influential for plant volume (explaining 25% of all spatial variation) than geographic position (regional level; 8%) or the neighbouring vegetation (at the plot level; 4%). An overall model including environmental factors at all scales performed better (27%), including the weather (bigger plants in warm and wet conditions), soil type (smaller plants on soils with more sand), and highlighting the negative effects of altitude, neighbouring vegetation and bare soil. Pollen and seed densities varied more than 200-fold between sites, with highest estimates in Croatia, Romania and Hungary. Pollen densities were highest on arable fields, while highest seed densities were found along infrastructure, both significantly higher than on ruderal sites. We discuss implications of these findings for the spatial scale of management interventions against A. artemisiifolia.

Open Access: Yes

DOI: 10.1007/s10530-017-1640-9

Combining transmission geometry laser ablation and a noncontact continuous flow surface sampling probe/electrospray emitter for mass spectrometry based chemical imaging

Olga S. Ovchinnikova Vilmos Kertesz Gary J. Van Berkel

Publication Name: Rapid Communications in Mass Spectrometry

Publication Date: 2011-12-30

Volume: 25

Issue: 24

Page Range: 3735-3740

Description:

This paper describes the coupling of ambient pressure transmission geometry laser ablation with a liquid-phase sample collection into a continuous flow surface sampling probe/electrospray emitter for mass spectrometry based chemical imaging. The flow probe/emitter device was placed in close proximity to the surface to collect the sample plume produced by laser ablation. The sample collected was immediately aspirated into the probe and onto the electrospray emitter, ionized and detected with the mass spectrometer. Freehand drawn ink lines and letters and an inked fingerprint on microscope slides were analyzed. The circular laser ablation area was about 210 μm in diameter and under the conditions used in these experiments the spatial resolution, as determined by the size of the surface features distinguished in the chemical images, was about 100 μm. Copyright © 2011 John Wiley & Sons, Ltd.

Open Access: Yes

DOI: 10.1002/rcm.5285

Boundary interpolation vs boundary elements: Theory and some applications

Csaba Gáspár

Publication Name: International Series on Advances in Boundary Elements

Publication Date: 2004-10-11

Volume: 19

Issue: Unknown

Page Range: 143-152

Description:

Domain and boundary type meshless methods based on the Direct Multi-Elliptic Interpolation Method are presented. The approach is equivalent to a special RBF-method but completely avoids the solution of large, full and ill-conditioned systems, thus, the computational cost is significantly reduced. The method is illustrated through the example of the usual Poisson problem. Both Dirichlet and Neumann boundary conditions are investigated. The domain version of the method results in particular solutions, while the boundary version can be applied to solve homogeneous problems. Along Neumann boundaries, either off-boundary points can be introduced or a boundary reconstruction technique based on boundary interpolation can be applied. Some further possible applications are also outlined.

Open Access: Yes

DOI: DOI not available