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The effect of coupling agent on the mechanical properties of injection molded polypropylene/wheat straw composites

Amar Patnaik László Lendvai

Publication Name: Acta Technica Jaurinensis

Publication Date: 2022-11-30

Volume: 15

Issue: 4

Page Range: 232-238

Description:

The objective of this work is to evaluate the effect of maleic anhydride-grafted polypropylene (MAPP) as coupling agent in polypropylene (PP)-based composites filled with ground wheat straw (WS) particles. The WS and the MAPP content in the composites was 10 wt% and 2 wt%, respectively. The samples were fabricated through melt compounding using a twin-screw extruder and then formed into dumbbell-shaped specimens by injection molding. The mechanical properties of neat PP and the composites with and without coupling were evaluated based on tensile and flexural tests and dynamic mechanical analyses (DMA). The experimental results showed that incorporating WS into the PP reduces its tensile strength by ~3 MPa, while improving its Young’s modulus by 0.14 GPa. The addition of MAPP compensated for the loss in tensile strength without affecting the modulus. Similar observations were made during the flexural tests as well, in which case, however, there was no loss revealed in the strength in the presence of WS due to the different types of load. The results of DMA analyses indicated an improved stiffness of WS-containing samples throughout the whole analyzed temperature range of 20-120 °C as a consequence of reduced chain mobility of PP caused by the stiff straw particles.

Open Access: Yes

DOI: 10.14513/actatechjaur.00677

Spectral moment segmentation and spectrogram synthesis for simulation of road vehicle vibrations

László Róbert Hári

Publication Name: Mechanical Systems and Signal Processing

Publication Date: 2022-11-15

Volume: 180

Issue: Unknown

Page Range: Unknown

Description:

Vibration testing procedures relying solely on a Fourier profile can introduce only stationary random vibrations. It is in contrast with the non-stationary and non-Gaussian nature of the Road vehicle vibrations (RVV). The following procedure segments the first four spectral moments of the time–frequency domain of RVV, constructs probability density arrays per frequency bins, and perform simulations according to random segment lengths and -root mean squares, yielding more realistic representations of RVV. The distribution of time- and frequency domain moments and normalized spectral entropies are confronted. The Probability-based spectrogram synthesis (PBSS) offers a data-driven stochastic modelling framework for simulating non-stationary RVV.

Open Access: Yes

DOI: 10.1016/j.ymssp.2022.109408

A review of the Digital Twin technology for fault detection in buildings

Henrik Kofoed Nielsen Paul Ragnar Svennevig Haidar Hosamo Hosamo Ammar N. Alnmr Kjeld Svidt

Publication Name: Frontiers in Built Environment

Publication Date: 2022-11-09

Volume: 8

Issue: Unknown

Page Range: Unknown

Description:

This study aims to evaluate the utilization of technology known as Digital Twin for fault detection in buildings. The strategy consisted of studying existing applications, difficulties, and possibilities that come with it. The Digital Twin technology is one of the most intriguing newly discovered technologies rapidly evolving; however, some problems still need to be addressed. First, using Digital Twins to detect building faults to prevent future failures and cutting overall costs by improving building maintenance is still ambiguous. Second, how Digital Twin technology may be applied to discover inefficiencies inside the building to optimize energy usage is not well defined. To address these issues, we reviewed 326 documents related to Digital Twin, BIM, and fault detection in civil engineering. Then out of the 326 documents, we reviewed 115 documents related to Digital Twin for fault detection in detail. This study used a qualitative assessment to uncover Digital Twin technology’s full fault detection capabilities. Our research concludes that Digital Twins need more development in areas such as scanner hardware and software, detection and prediction algorithms, modeling, and twinning programs before they will be convincing enough for fault detection and prediction. In addition, more building owners, architects, and engineers need substantial financial incentives to invest in condition monitoring before many of the strategies discussed in the reviewed papers will be used in the construction industry. For future investigation, more research needs to be devoted to exploring how machine learning may be integrated with other Digital Twin components to develop new fault detection methods.

Open Access: Yes

DOI: 10.3389/fbuil.2022.1013196

Best approximation of OWA Olympic weights under predefined level of orness

Lucian Coroianu István A. Harmati Robert Fuller

Publication Name: Fuzzy Sets and Systems

Publication Date: 2022-11-05

Volume: 448

Issue: Unknown

Page Range: 127-144

Description:

An ideal type of OWA aggregation operator is the one constructed on the so-called Olympic weights. The orness of this operator is 1/2. Therefore, sometimes we need a trade-off between the desire of having an OWA aggregation operator with weights as close as possible to the Olympic ones and the desire of having a predefined level of orness. In this paper, we choose these optimal weights by minimizing the Euclidean distance to the Olympic weights vector under the constraint of preserving a given level of orness. First, in the case n=4, we propose an iterative algorithm where the optimal solution is given for all possible values of the orness, values that are grouped along a partition of the unit interval. This iterative algorithm will inspire us to deduce the optimal weights in the general case. Consequently, we will obtain the analytical solution of the optimal weights as a function depending on the orness level.

Open Access: Yes

DOI: 10.1016/j.fss.2022.07.009

On stability of maximal entropy OWA operator weights

István A. Harmati Imre Felde Robert Fuller

Publication Name: Fuzzy Sets and Systems

Publication Date: 2022-11-05

Volume: 448

Issue: Unknown

Page Range: 145-156

Description:

The maximal entropy OWA operator (MEOWA) weights can be obtained by solving a nonlinear programming problem with a linear constraint for the level of orness. Since the exact MEOWA weights are not known for the general case we can only find approximate solutions. We will prove that the nonlinear programming problem for obtaining MEOWA weights is well-posed: it has a unique solution and each MEOWA weight changes continuously with the initial level of orness. Using the implicit function theorem we will show that MEOWA weights are Lipschitz-continuous functions of the orness level. The stability property of the MEOWA weights under small changes of the orness level guarantees that small rounding errors of digital computation and small errors of measurement of the orness level can cause only a small deviation in MEOWA weights, i.e. every successive approximation method can be applied to the computation of the approximation of the exact MEOWA weights.

Open Access: Yes

DOI: 10.1016/j.fss.2022.01.003

Determination of Measurement Parameters for Vibration Analysis by Bus

Péter Szalai Péter Horváth F. Hajdu Rajmund Kuti M. Brinissat Antal Apagyi Cs Papp

Publication Name: Strojnicky Casopis Journal of Mechanical Engineering

Publication Date: 2022-11-01

Volume: 72

Issue: 2

Page Range: 189-200

Description:

From the point of view of field examinations, especially in the case of measurements done by instruments, it is crucially important to determine measurement conditions. Accurate identification of parameters enables accurate and certified measurement results to be achieved. In our work, we represent the determination of measurement conditions for harmful vibrations occurring during urban road transport of an Ikarus 55 type long-haul bus. This is a favourable basis for further vibration analysis regarding other buses.

Open Access: Yes

DOI: 10.2478/scjme-2022-0028

Perceived usefulness of yoga to maintain well-being and in relation to COVID-19 cases among Hungarian yoga practitioners

Henriett Nagy Sándor Rózsa Miklós Bánhidi Gusztáv J. Tornóczky

Publication Name: Journal of Sports Medicine and Physical Fitness

Publication Date: 2022-11-01

Volume: 62

Issue: 11

Page Range: 1541-1551

Description:

BACKGROUND: The present COVID-19 epidemic has had a considerable impact on the mental health of individuals worldwide. Research projects suggests potential benefits of yoga practice for prevention, or as medical supplementation in relation to the present pandemic. This study investigated the association between yoga and health status, and how the frequency of yoga practice affected the mental well-being (MWB) of the respondents. METHODS: Hungarian yoga practitioners (N.=379) aged 20 to 75 years (93.4% female) were asked about their personal health, perceived usefulness of yoga practice for COVID-19 cases and their MWB. Data were collected between April 17 and May 17, 2021. The measurement tool used was an online questionnaire including sociodemographic data, characteristics of yoga practice, COVID-19 and health related questions, and WHO Well-being Index (WBI-5). Associations were examined through ANOVA and X2 tests. RESULTS: There was a significant difference among the yoga practice groups by weekly frequency (once a week, 2-3 times a week, 4-5 times a week, daily) on the total mean score of well-being (WBI-5), F (3, 373) =12.97, P<0.001, ηp 2=0.094. The daily practice of yoga showed the highest MWB. CONCLUSIONS: According to our findings, it can be stated that regular yoga practice is associated with higher level of MWB which can be successful in dealing with COVID-19 issues such as stress and depression.

Open Access: Yes

DOI: 10.23736/S0022-4707.22.13341-4

Valorization of spent mushroom substrate in combination with agro-residues to improve the nutrient and phytohormone contents of vermicompost

Chuleemas Boonthai Iwai Balasubramani Ravindran Babett Greff Supawadee Ruangjanda Soon Woong Chang

Publication Name: Environmental Research

Publication Date: 2022-11-01

Volume: 214

Issue: Unknown

Page Range: Unknown

Description:

In recent years, enormous amounts of spent mushroom substrate (SMS) have been generated because of the rapid development of mushroom production. Since the conventional disposal methods of these residues can cause serious environmental problems, alternative waste management techniques are required to ensure sustainable agriculture. However, SMS might be not suitable for vermicomposting when used alone. Therefore, the primary purpose of this study was to investigate the effect of Azolla microphylla (Azolla) biomass, eggshells, fruit peels, and cassava pulp on the biodegradation process of SMS. The results showed the treatments supplemented with cassava pulp and fruit peel waste improved the growth of earthworms, while the carbon-to-nitrogen ratio of these vermicomposts decreased significantly (p < 0.05) due to the improved total nitrogen contents (7.64 g kg−1 and 6.71 g kg−1). Concerning the degradation process and the vermicompost quality, the addition of these agro-residues facilitated the enzyme activities (cellulase, urease, and alkaline phosphatase) and increased the total macronutrient (P, K, Mg, and Ca) and phytohormone (fruit peel waste: AA, GA3, and cytokinin; cassava pulp: cytokinin) contents of the final products compared to the control treatment. On the other hand, Azolla had no additional effect on the fecundity and growth of Eudrilus eugenia. Meanwhile, the treatment supplemented with eggshells was high in Mg (7.15 g kg−1) and Ca (305.6 g kg−1). Overall, the combined decomposition of SMS-based bedding material with Azolla, eggshells, fruit peel waste, and cassava pulp resulted in mature organic fertilizers with improved chemical properties.

Open Access: Yes

DOI: 10.1016/j.envres.2022.113771

First Report of Coniella granati Causing Leaf Spot of Pomegranate (Punica granatum) in Hungary

M. Petróczy László Palkovics A. Tóth L. Szendrei P. Salamon

Publication Name: Plant Disease

Publication Date: 2022-11-01

Volume: 106

Issue: 11

Page Range: 2995

Description:

No description provided

Open Access: Yes

DOI: 10.1094/PDIS-10-21-2230-PDN