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Found 6414 publications

Fuzzy Logic and Push-Out Test Innovations for Fiber-Reinforced Self-compacting Concrete Assessment

Oveys Ghodousian Majid Movahedi Rad Vahid Shafaie Géza Herczeg

Publication Name: Fib Symposium

Publication Date: 2024-01-01

Volume: Unknown

Issue: Unknown

Page Range: 855-862

Description:

This research addresses the deterioration of concrete infrastructures, emphasizing the efficacy of Fiber-Reinforced Self-Compacting Concrete (FRSCC) in repair applications. The study investigates the bond strengths between new and existing concrete layers, employing both experimental and numerical methods to evaluate traditional and innovative testing approaches, including slant shear and push-out tests. Results demonstrate that FRSCC, enhanced with polypropylene fibers, significantly improves structural resilience and mechanical properties. The introduction of fuzzy logic models further refines the prediction of bond strengths, offering a robust framework for future concrete technology advancements.

Open Access: Yes

DOI: DOI not available

Optimizing the Performance of the Iptables Stateful NAT44 Solution

Keiichi Shima G. Lencse

Publication Name: Infocommunications Journal

Publication Date: 2023-01-01

Volume: 15

Issue: 1

Page Range: 55-63

Description:

—The stateful NAT44 performance of iptables is an important issue when it is used as a stateful NAT44 gateway of a CGN (Carrier-Grade NAT) system. The performance measurements of iptables published in research papers do not comply with the requirements of RFC 2544 and RFC 4814 and the usability of their results has serious limitations. Our Internet Draft has proposed a benchmarking methodology for stateful NATxy (x, y are in {4, 6}) gateways and made it possible to perform the classic RFC 2544 measurement procedures like throughput, latency, frame loss rate, etc. with stateful NATxy gateways using RFC 4814 pseudorandom port numbers. It has also defined new performance metrics specific to stateful testing to quantify the connection setup and connection tear down performance of stateful NATxy gateways. In our current paper, we examine how the performance of iptables depends on various settings, and also if certain tradeoffs exist. We measure the maximum connection establishment rate, throughput and tear down rate of iptables as well as its memory consumption as a function of hash table size always using 40 million connections. We disclose all measurement details and results. We recommend new settings that enable network operators to achieve significantly higher performance than using the traditional ones.

Open Access: Yes

DOI: 10.36244/ICJ.2023.1.6

Exchange rate impacts on international trade

Laszlo Vasa Robert Magda Jalil Mehtiyev

Publication Name: Economic Annals Xxi

Publication Date: 2021-07-10

Volume: 190

Issue: 5

Page Range: 12-22

Description:

As international trade activities are increased, there are more regulative practices which might be barriers to trade. One of such hindrances is exchange rate volatility that afects trade activities both directly and indirectly. Exchange rate volatility of currencies can afect the trade engagements and as well as the trade balance of a country. One of the implications of the study is that the impacts of monetary policy changes on trade activities can be noticed signifcantly in the long-term. While impacts on export levels are usually immediate, import levels are changed in long-run. The research analyzes the correlation between infation and devaluation and clearly states their impacts on trade balance. The case study about devaluation of the currency of Azerbaian elaborates the impacts of currency volatility on exports which is illustrated and analyzed in this research. Moreover, infation and devaluation correlations and their impacts on import level of a country are studied through correlation and multiple regression analyses based on the data exported from OECD and World Bank. The results conclude that exchange rate volatility signifcantly impacts the trade balance in terms of imports and exports. Given the results, exchange rate is a non-trade barrier and afects foreign trade.

Open Access: Yes

DOI: 10.21003/EA.V190-02

Analysis of the Stressed State of Sand-Soil Using Ultrasound

Szabolcs Fischer Ulf Gerber Mykola Sysyn Lukas Benedikt Schumacher

Publication Name: Infrastructures

Publication Date: 2023-01-01

Volume: 8

Issue: 1

Page Range: Unknown

Description:

The maintenance of the ballast substructure is an important cost-driver for railway systems. The problem is that today’s condition monitoring methods are insufficient to collect detailed data on the compaction and stress allocation inside the ballast bed. That makes it challenging to improve the maintenance technology and organization. This study aimed to investigate the applicability of the ultrasound method for analyzing the state of stress of sand-soil and the relation between the residual stress and wave propagation velocity. The experiments on the sand in a box with different allocations of the ultrasonic receivers and pressure measurement cells were produced under different external loading. In addition, the vertical and horizontal stress distributions were measured. The results showed a correlation between the test load, the state of stress, and the ultrasound propagation velocity. Moreover, the residual stresses after the loading cycles were analyzed.

Open Access: Yes

DOI: 10.3390/infrastructures8010004

Eddy current analysis with nonlinearity

Miklós Kuczmann Dániel Marcsa

Publication Name: Pollack Periodica

Publication Date: 2008-08-01

Volume: 3

Issue: 2

Page Range: 97-109

Description:

The paper deals with an eddy current field problem as a case study. The aim is to find the solution of the problem by the help of the Finite Element Method (FEM), and the T, , potential formulation taking the nonlinearity of the material into account. The effect of nonlinearity has been approximated with an inverse tangent type analytical model. The nonlinearity has been handled by the polarization method coupled with the Fixed-point iteration technique. © 2008 Akadémiai Kiadó.

Open Access: Yes

DOI: 10.1556/Pollack.3.2008.2.9

Ultrasonographic assessment of the cervix for prediction of spontaneous preterm birth in singleton pregnancies

Zoltán Papp Zorán Belics

Publication Name: Donald School Journal of Ultrasound in Obstetrics and Gynecology

Publication Date: 2021-01-01

Volume: 15

Issue: 1

Page Range: 49-63

Description:

Spontaneous preterm birth remains a major cause of neonatal morbidity and mortality across the world. Hence, there is an urgent need to find and implement diagnostic methods and interventions that can reduce this public health treat. The ultrasonographic assessment of the cervix is one tool that can be utilized to identify women at increased risk who may be candidates for preventive interventions. There are three main characteristics of the cervix, which can be evaluated during the ultrasound examination of the cervix: cervical length (CL), funneling and cervical gland area. Cervical shortening is one of the first steps in the processes leading to labor and can precede labor by several weeks. Because shortening begins at the internal cervical os and progresses caudally, it is often detected on ultrasound examination before it can be appreciated on physical examination. This is equally true for funneling and cervical gland area (CGA), which cannot be assessed with the physical examination. Based on previous experiences, the timing and frequency of ultrasonographic assessment of the cervix is primarily based on the patient’s prior obstetric history (low-risk women are screened once at 18–24 weeks of gestation; high-risk population usually begins screening at about 16 weeks of gestation and the frequency depends on the measurement result). Classically the diagnosis of short cervix is defined when the CL is less than or equal to 25 mm at these gestational weeks, with the best prediction for PTB obtained at 16–24 weeks of gestation. The CL measurement, evaluation of funneling and CGA together increased the sensitivity of cervical screening for PTB and appeared to be powerful predictor of PTB before 32 weeks gestation. Generally, the importance of positive test is to try to recognize cervical changes on time, to plane the adequate therapy, to prepare for sufficient intrauterine transport, and to administered course of antenatal corticosteroid therapy to women at risk for PTB reduced the incidence and severity of respiratory distress syndrome (RDS) and mortality in offspring. Many interventions (bed rest, lifestyle intervention, cervical cerclage, pessary, progesteron, indomethacin, antibiotics, etc.) have been proposed in an attempt to prevent PTB depending on risk classification.

Open Access: Yes

DOI: 10.5005/jp-journals-10009-1683

SPECTRAL ACCELERATION FROM THE 2017 SARPOL-E ZAHAB EARTHQUAKE: PREDICTIONS AND OBSERVATIONS

Hayder Thabit Al Hudaib R. Ibrahim Richard P. Ray

Publication Name: World Conference on Earthquake Engineering Proceedings

Publication Date: 2024-01-01

Volume: 2024

Issue: Unknown

Page Range: Unknown

Description:

This article investigates the spectral acceleration of the ground motion generated by the 2017 Sarpol-e Zahab earthquake, examining the spatial distribution of the observed spectra at different periods, revealing a distinct influence of source directivity. The earthquake motions were acquired by the Iranian Strong Motion Network (ISMN), and data from a total of 110 seismic stations were obtained from their network for the purpose of the present study. The regions located south of the epicenter experienced a higher spectral acceleration value compared to those sites located to the north. In addition, estimates from ground motion prediction equations (Abrahmson et al., 2014, ASK14; Akkar et al., 2014, ASB14) provided a basis for comparison. These equations predicted intensities over various distances and periods. The residual analysis results indicate that the ASB14 model provides a more accurate fit when compared to the ASK14 model for distances less than 300 km. However, for distances greater than 300 km, the ASK14 model demonstrates a better fit. The derived response spectra play a significant role in evaluating maximum response amplitudes and for seismic hazard studies. Our assessments combined PSA information with source characteristics, geology, soil conditions, and epicentral distance. The current study highlights the impacts of the 2017 Sarpol-e Zahab earthquake on the Darbandikhan Dam, which caused cracking on the road pavement along the Dam crest and horizontal and vertical displacement in some parts of the dam. Finally, the study evaluates the strong-motion distribution maps of acceleration response spectra (PSA) with 5% damping at various period intervals from (0.1 to 2.0 sec) on the dam site, which could produce the consequences observed for the dam.

Open Access: Yes

DOI: DOI not available

Scalar hysteresis measurement using FFT

Miklós Kuczmann

Publication Name: Journal of Optoelectronics and Advanced Materials

Publication Date: 2008-01-01

Volume: 10

Issue: 7

Page Range: 1828-1833

Description:

The paper deals with a possible realization of eliminating the effect of noise in scalar hysteresis measurements. The measured signals have been transformed into the frequency domain, and after applying digital filter, the spectrums of the filtered signals have been transformed back to the time domain. The proposed technique results in an accurate noise removal algorithm. The paper illustrates a fast controlling algorithm applying the inverse of the actually measured hysteresis loop, and another proportional one to measure distorted flux pattern. Developing the mentioned algorithms aims the controlling of more complicated phenomena, i.e. measuring the vector hysteresis characteristics.

Open Access: Yes

DOI: DOI not available

Shear Buckling Resistance of I-Beams with Partially Stiffened Webs

G. Hajdú Hartmut Pasternak

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 358-365

Description:

This paper presents the results of laboratory tests and numerical analysis for plate girders with partial height end stiffeners. Design rules for rigid end posts and non-rigid end posts are given in EN 1993-1-5:2006 but the shear resistance of partially stiffened webs is not mentioned. The use of non-tightly fitted stiffeners is hazardous due to insufficient investigations of the real behaviour. To discover this problem parametric studies on beams with different web slenderness are examined with the usage of advanced numerical simulations. The accuracy of the EN 1993-1-5:2006 standard design rule for partially stiffened beams is also examined. The results of the numerical simulations shows that the shear buckling capacity of girders is lower than the design recommendation where the height of the web stiffener is b5% of the web height. For girders with full height stiffeners the EN 1993-1-5:2006 standard leads conservative results.

Open Access: Yes

DOI: 10.3233/ATDE240567