KTU Open Journal Systems (Kaunas University of technology)
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“Stylized facts” in Price Dynamics: Do They Matter for ESG Financial Markets?
No full textWe investigate the presence of “stylized facts” within the ESG segment of the developed financial markets. The effects resulting from their presence are relevant given their impact on asset pricing, portfolio management, and even the efficiency of policy decisions. Moreover, during turbulent periods, the effects and presence of such elements can enable integration to act as a net transmitter of volatility. To explore this concept, we employed a broad and diversified toolset to detect their presence and influence. We tested five developed ESG indices, covering a time window from January 2014 to March 2023, by employing high-frequency data. The selection of indices captures and accounts for different geographical settings. The results suggest that “stylized facts” are present in the ESG segment of developed markets and volatility can spill over from market to market and fuel the contagion effect on a global scale, via the integration process and its effects
Effect of Annealing Temperature and Time Over the Microstructural, Mechanical and Electrical Properties of Deformed Al Wires (A6)
No full textAl wires with different deformation were obtained by cold-drawing and annealing treatment. The microstructure, mechanical, and electrical properties of the wires annealed at different temperatures and times were studied using SEM, universal testing machine, and DC resistance tester. The results indicate that as the annealing temperature and time increase, the UTS of Al decreases, while the EL and EC increase simultaneously. During the annealing procedure, recrystallization is observed to begin at 300 ℃ and complete at 350 ℃. Compared with the beginning of recrystallization, the recrystallized grain diameter increases from 11.34 μm to 20.59 μm, while the UTS decreases by 24.1 %, the EL increases by 74 %, and the EC increases by 3 %. When annealed at 315 ℃ for 1h, the recrystallization begins in the samples with 90 % deformation, and completes when the annealing time is increased to 4.5 h, the grain diameter increases from 7.67 μm to 20.71 μm; though the tensile decreases by 24.3 %, the EL and EC increase by 97.5 % and 2.8 %, respectively
The Application of IPMC Material Sensors in Collecting Flow Rates of Products
No full textWith the rapid development of the economy and society, the demand for e-commerce products such as ocean speed sensors, heart rate sensors, and fingerprint recognition sensors is constantly increasing. This study selected an ion-exchange polymer metal composite (IPMC) with a certain potential for flow rate sensor applications to design experiments to test the performance of the flow rate sensor constructed with this material. As the density of the medium decreased, the deformation at the tip of the IPMC material decreased, and the pressure difference on the flow field cross-section increased. The densities of seawater and alcohol were 1072 kg/m3 and 783 kg/m3 respectively, with corresponding tip deformation and pressure difference of 0.20 mm and 0.14 mm, as well as 327 Pa and 86 Pa, respectively. As the temperature of seawater increased, the viscosity value of the medium decreased, and there was no significant change in the deformation and pressure difference at the tip of the corresponding IPMC. It indicates that within the range of changes in seawater viscosity, temperature has little effect on the deformation of IPMC, or in other words, IPMC has strong temperature adaptability under these conditions. When other conditions are the same, the larger the flow rate, the greater the deformation of IPMC. The experimental results demonstrate that under conditions of high length, width, and flow velocity, the IPMC flow velocity sensor designed in this study has high measurement accuracy. The research results contribute to the design of new IPMC flow rate sensors for e-commerce products
Comparison of Compression Parallel to Grain of Acacia Hybrid for Untreated and Treated at Different Combination of Age Groups
No full textSarawak\u27s wood-based industries face challenges due to a shortage of wood-based raw materials. Research on the Acacia hybrid species is limited, but it is crucial for the timber engineering field. Acacia hybrids have been selected for reforestation projects due to their rapid growth. Since 2001, various license holders have planted Acacia mangium and its hybrids on over 245,000 hectares in Sarawak. The species were collected from a plantation area owned by Daiken Sarawak Sdn Bhd. Tests on physical properties, namely moisture content (MC) and basic density, were carried out. Meanwhile, tests on mechanical properties for both untreated and treated samples were also conducted, including static bending tests (modulus of rupture, MOR and modulus of elasticity, MOE) and compression parallel to the grain test. All the tested samples were in air-dry condition, with the MC ranging from 12 % to 19 %. The specimens were prepared according to BS 373:1957 and Method of Testing Small Clear Specimens of Timber. All tested results were analyzed using statistical methods to determine mean results. All the results that had been tested were analyzed using statistical analysis as mean results. Comprehensive testing of Acacia hybrid wood treated with copper chrome arsenic (CCA) has significantly improved its physical and mechanical properties. The treatment results in higher density and strength, influenced by growth and structural variations of the wood. It also enhances moisture retention, boosting the wood\u27s hydrophobic properties and durability. Treated wood shows increased Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) in static bending tests, demonstrating enhanced resistance to bending and structural integrity. Compression tests reveal that treated wood is 27% stronger than untreated, confirming its superior ability to withstand compressive forces. From this study, the best age combination product is 10y+10y, and it can be concluded that the comprehensive testing of Acacia hybrid wood reveals treatments enhance its physical and mechanical properties
Size and Shape Effect on Melting Temperature of Metallic Nanocrystals
No full textThe melting temperature serves as a pivotal physical property governing the thermal stability of metallic nanocrystals, notably exhibiting substantial variability with respect to size and dimensionality. While several quantitative models exist to elucidate how the melting temperature correlates with the size and dimensionality of metallic nanocrystals, these models often fall short of capturing the synergistic influence of both factors comprehensively. To address this gap, our study employs a novel thermodynamic framework grounded in cohesive energy theory, requiring no arbitrary adjustable parameters. We find that, under constant conditions, the melting temperature of metallic nanocrystals diminishes as their size decreases. In terms of dimensionality, we establish a hierarchy as follows: nanoparticles > nanowires > thin films. Moreover, we reveal a non-linear relationship between the melting temperature and the inverse of dimensionality. Through rigorous validation via both simulations and empirical experiments, we corroborate the high accuracy of this thermodynamic model in predicting the variations in the melting temperature of metallic nanocrystals due to changes in size and dimensionality. The model in this study is primarily applicable to metallic nanocrystals and the potential applicability to other types of nanocrystals under certain conditions is briefly mentioned.
Influence of Infill Design in Fabrication of 3D-printed PLA Parts Using FDM
No full textThe present work examines the mechanical characteristics of polylactic acid (PLA) samples manufactured in 3D printing using various infill patterns. The infill patterns investigated are cuboid, grid, and octet, prepared at a constant infill density of 50 %. The study aimed to identify the most suitable infill pattern for specific mechanical requirements, considering tensile, compression, and flexural behaviour. Experimental testing was conducted on the 3D-printed PLA specimens to assess their mechanical performance. The findings reveal that the octet infill pattern showed the highest mechanical qualities across all three tests, including tensile, flexural, and compression evaluations, indicating improved strength and stability. The octet infill pattern samples had the highest tensile value of 17.3 MPa, maximum flexural stress of 35 MPa, and maximum compression stress of 34.4 MPa. These results emphasize the need to choose suitable infill patterns to adjust the mechanical properties of 3D-printed PLA components to meet particular application requirements
1,2,4-Triazole and Its Derivatives as Corrosion Inhibitors for Aluminum Brass (HAl77-2) in 3.5 wt.% NaCl Solution
No full textIn this work, the 1,2,4-triazole and its derivatives were used as target corrosion inhibitors, the corrosion inhibition of 1,2,4-triazole (TAZ), 3-amino-1,2,4-triazole (ATA) and 3,5-diamino-1,2,4-triazole (DAT) in 3.5 wt.% NaCl solutions for aluminum brass (HAl77-2) are reported. The inhibition properties and mechanism were investigated by weight loss tests, electrochemical tests (electrochemical impedance spectroscopy and linear polarization resistance tests), surface characteristic analysis (scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) tests), and quantum chemistry calculations. The results showed that TAZ, ATA, and DAT effectively inhibited the corrosion of HAl77-2. The maximum inhibition efficiencies of the three corrosion inhibitors were 84.4 %, 86.4 %, and 87.1 %, respectively. The adsorption processes followed the Langmuir adsorption isotherm model and were of mixed type, i.e., both physisorption and chemisorption. SEM and EDS tests confirmed the effective adsorption of the TAZ, ATA, and DAT on the HAl77-2 surface. The results of quantum chemistry calculations were consistent with the electrochemical test results
Effect of Dune Sand in Physico-mechanical Properties and Sustainability of Calcareous Mortar Modified by Styrene-butadiene-rubber Latex
No full textAs part of environmental preservation efforts, and to satisfy ecological and environmental requirements, from the recovery of certain materials widely abundant in remote areas, to reduce the excessive exploitation of natural sources, this study aimed to evaluate dune sand and crushed limestone sand. Thirteen mortar mixtures were manufactured, varying the weight substitution rate of crushed limestone sand by dune sand. The substitution rates were set at 0 %, 10 %, 20 % and 30 %. To reduce the impact of the greenhouse effect due to CO2 emissions resulting from cement manufacture, and as an ecological replacement, we carried out a partial mass replacement of the cement by styrene-butadiene rubber (SBR) latex of the order of 2.5 % and 5 %. This experimental study evaluates physico-mechanical properties such as porosity, absorption and mechanical resistance. As for the great importance of durability, the study of the tests (mass loss, visual examination and X-ray diffraction) after immersion of the samples in the 5% H2SO4 are evaluated. The results indicate the possibility of substituting calcareous sand with dune sand at a rate of 30 % and using 5 % of SBR Latex, to obtain beneficial results regarding the tensile strength by flexure by values of 38.83 % and 47.2 % at 28 and 90 days respectively, where the same mixture outperformed (control mortar M1 28 days) by 3.9 % in 90 days in compression, regarding durability, the decrease in mass loss was 28.40 % compared to M1
Investigating the Relationship Between Incineration Temperature, Rice Husk Ash (RHA) Characteristics, and Modified Asphalt Performance
No full textMixing rice husk ash into asphalt can not only avoid resource waste, but also improve the performance of asphalt. However, the incineration temperature of rice husk ash affects its activity, which in turn affects the performance of its modified asphalt. To investigate the influence of rice husk ash (RHA) prepared at different incineration temperatures on its properties and the performance of its modified asphalt, the amorphous SiO2 content in RHA was determined using X-ray fluorescence spectrometry (XRF) and X-ray diffraction (XRD). Additionally, the microstructure of RHA was analyzed through scanning electron microscopy (SEM). RHA obtained at different incineration temperatures was utilized in the base asphalt as an additive to produce rice husk ash modified asphalt (RHAMA), and the high and low temperature performance, temperature sensitivity, and creep recovery of RHAMA were evaluated by the dynamic shear rheology (DSR) test, the bending beam rheology (BBR) test, and the multi-stress creep recovery (MSCR) test. These results were combined with microscopic analyses of RHA to assess the impact of incineration temperature on the performance of RHAMA. The findings reveal that when the calcination temperature exceeds 600 ℃, the amorphous SiO2 in RHA transitions to a crystalline phase. The incorporation of RHA enhances the high temperature performance and creep recovery of the base asphalt but reduces its temperature sensitivity and low temperature performance. As the incineration temperature of RHA increases, the high temperature performance and creep recovery of RHAMA decline, while temperature sensitivity and low temperature performance improve. The optimal calcination temperature for RHA is 600 ℃, at which the amorphous SiO2 content is maximized, resulting in the most significant improvement in the performance of the base asphalt
Controlled Surface Texturing of Dental Implants via Q-Switched Nd:YAG Laser: Toward Enhanced Osseointegration
No full textThis study aims to propose an ideal surface treatment method that overcomes the disadvantages of the existing implant surface treatment method and increases the surface area per unit area of the implant for enhanced adhesion between the implant and bone tissue. Generally used implants do not have a screw structure or surface treatment method according to the bone quality of the human body. It is essential to establish precise and systematic process parameters when performing the surface treatment of implants using lasers. Therefore, this study intends to use a Q-switching Nd:YAG laser with a wavelength of 1.06 um to develop a process for modifying the surface of an implant so that it can become a biocompatible structure. In order to examine the processing characteristics according to the change in the laser beam overlap of the pulsed laser, the change in scribing width according to the power, and the change in scribing width according to the duty increase. The results of this study suggest that implant surface treatment technology using lasers will be secured and used for actual implant surface treatment