Study Of Behavior Research Articles

Statistical Study of the Mechanical Behavior of the New Fiber from the Strelitzia Juncea Plant Fibers: Application in Ecological Yarns

ABSTRACT To develop efficient, durable, and eco-friendly natural fiber composites, this study examines the physical properties of Strelitzia Juncea (SJ) fiber for potential industrial use. The focus is on how gauge length affects mechanical properties of SJ fibers, aiming to manufacture textile yarns. Tensile tests were performed on SJ yarns of varying diameters (0.95, 1.26, and 1.76 mm). In addition, 150 fibers across five-gauge lengths (GL) from 10 to 50 mm gave a strength of 731 to 270 MPa and a Young’s modulus of 28 to 31 GPa, with statistical analysis applied to evaluate the data’s variability. Statistical techniques were applied to assess and quantify this dispersion. Results were analyzed using Weibull distributions with different probability indices, along with least squares (LS) and maximum likelihood (ML) estimation techniques. Furthermore, for each tensile strength characteristic, a one-factor analysis of variance (ANOVA) was performed across the five groups.

The study of electrochemical hydrogen storage behavior of the MIL-53 (M=Cu, Al, Fe and Cr) framework on the Ag/f-MWCNTs substrate

The goal of this study is to determine the effect of some metal on functionalized multi-walled carbon nanotubes (f-MWCNTs) as well as the impact of central metal on metal–organic frameworks, and the effect of both on the hydrogen storage performance. Another objective of the current study is to modify MOFs and introduce them to the carbonaceous materials. Through this technique which is based on the hydrogen “spillover effect”, the obtained nanocomposite witnessed a significant increase in hydrogen uptakes capacity as compared to the pristine samples. To this end, f-MWCNTs is designed with Cu2+, Ni2+, Co2+ and Ag+. According to the electrochemical hydrogen storage results, the best performance belongs to the Ag/f-MWCNTs which equals 1850 mAhg−1; this figure has increased more than 3.5 times as compared to the f-MWCNTs. Besides, MIL-53 (M=Cu, Al, Fe and Cr) is synthesized as important MOFs owing to their unique structural properties. Among these mentioned MOFs, the MIL-53(Cr) with the highest hydrogen storage capacity which equals 3100 mAhg−1, is selected to be combined with Ag/f-MWCNTs. Eventually, MIL-53(Cr)/Ag/f-MWCNTs nanocomposites, are prepared at ambient pressure and temperature. The hydrogen storage capacity of MIL-53(Cr)/Ag/f-MWCNTs is 4500 mAhg−1, which improved significantly at about 2.4 times higher than Ag/f-MWCNTs sample and 1.4 times higher than MIL-53(Cr) sample.

Experimental and numerical analyses on the modal behaviour of an aluminium alloy sheet

Abstract The study of modal behaviour for vehicle body panels represents a field of interest for automotive engineering, having a major influence on automotive comfort, with respect to vehicle noise, vibration and harshness, but also concerning the durability of vehicle body. The investigation of natural frequencies and vibration mode shapes is crucial in the design phase, because essential information can be obtained concerning the behaviour of the components in dynamic conditions. The current paper focuses on the investigation of vibration modes and frequency response function on an aluminium alloy sheet. The aim of the paper is to perform the study of modal behaviour both experimentally and theoretically, through measurements using the impact hammer method and respectively through finite element analysis. The CAD model of the aluminium alloy sheet has been developed in Catia V5 environment in view of elaborating the finite element model, which has been used for investigation of modal behaviour, taking into account the case of free vibrations. Through the modal finite element analysis performed in Ansys Workbench, the natural frequencies of the aluminium alloy sheet, as well as the corresponding mode shapes have been obtained. Experiments have been performed on an aluminium alloy sheet, mounted on an elastic support with low natural frequency. The impact hammer method has been used for obtaining the natural frequencies, through frequency analysis of accelerations measured with two piezoelectric accelerometers mounted on the aluminium alloy sheet. The frequency response function has been computed from the response acceleration measured on the aluminium alloy sheet and the impact force measured using the force transducer of the impact hammer. Virtual instruments have been developed in LabVIEW environment for data acquisition, time domain and frequency analysis, as well as for determining the frequency response function using the measured signals. The natural frequencies obtained from the finite element analyses have been compared to the results of measurements and very good similarities have been ascertained. The experimental investigation of modal behaviour contributed to the validation of the finite element model, but further research is required to investigate the possibilities of improving the modal behaviour of the aluminium alloy sheet.

Study of slag formation behavior in iron ore pellets based on thermodynamic calculations and experiments

To investigate the mechanism of slag formation during pellet consolidation, we combined thermodynamic calculations and experimental methods to study the effects of roasting temperature, basicity, and SiO2 content on slag formation. The results indicate that as the temperature increases, the solid phases clinopyroxene, orthopyroxene, and melilite transform into slag within the pellet. The roasting temperature and basicity of slags formed by different particles varied considerably. At 1250 °C, the slag content is less than 5 % in low-silica fluxed pellets, less than 15 % in medium-silica fluxed pellets, and up to approximately 20 % in high-silica fluxed pellets. Phase diagram analysis showed that CaFe2O4 and Ca2Fe2O5 formed in the pellet due to basicity differences SEM-EDS analysis showed that the slag in fluxed pellets primarily comprises the silicates Ca3Fe2(SiO4)3 and (Mg, Fe)2SiO4, as well as ferrate. The slag is distributed in a reticulated pattern within the pellets, with some quartz remaining undissolved in the slag phase and existing independently in pores.

Study of the co-firing behavior of dielectric ceramic (Zr0.8Sn0.2)TiO4 and NiZn ferrite laminated composites

Study of the co-firing behavior of dielectric ceramic (Zr0.8Sn0.2)TiO4 and NiZn ferrite laminated composites

From quasi-static to dynamic: Experimental study of mechanical and fracture behaviour of epoxy resin

Epoxy polymers are extensively used in various engineering applications such as aerospace, defence, sports, automotive etc. This article focuses on the in-depth mechanical characterisation of EPOFINE®-1564, a Bisphenol-A-based liquid epoxy resin under various loading conditions. To predict the tensile and compressive behaviour of the representative epoxy resin, quasi-static experiments were performed in the range of 10−4 to 10−2s−1 on Universal testing machine (UTM) while the dynamic experiments were conducted using Split Hopkinson Pressure Bar (SHPB) for high strain rates (1136–2833 s−1). In this study, 3D Digital Image Correlation (DIC) was also used to evaluate the specimen's full-field displacement profile over a wide range of strain rates. Analysis of various mechanical properties such as elastic modulus, yield strength, and ultimate strength, revealed that the epoxy polymer is strain rate dependent within the considered strain rate range. For understanding the fracture behaviour, three-point bend (TPB) experiments were also carried out for both quasi-static (1–10 mm/min) as well as dynamic (10–15 m s-1) regimes. Dynamic fracture experiments were performed using the modified Hopkinson Pressure Bar (MHPB). The fracture toughness was determined through load vs crack mouth opening displacement (CMOD). Fracture toughness was found to increase with the displacement rate due to the significant plastic deformation under quasi-static range. Conversely, it was found to decrease under dynamic loading because of absence of plastic deformation resulting in brittle fracture. The fracture surface of the specimen was examined through a high magnification digital microscope.

Dynamic creep of Al2O3 whisker-reinforced ZrO2 ceramic composite

Previous studies on the creep behavior of ceramic materials were primarily conducted under static loads. However, the majority of applications for ceramic materials are subject to dynamic loads, and there is a paucity of research conducted in this area. In this work, we report for the first time the creep behavior of Al2O3 whisker-reinforced ZrO2 composites under dynamic pressure. The results showed that the sample crept under dynamic pressure produced higher creep rate and lower activation energy compared to static pressure. By analyzing the creep data and microstructures, we showed that the dynamic pressure can enhance dislocation motion and transform the creep mechanism from diffusion-controlled grain-boundary sliding to dislocation-controlled grain-boundary sliding. This work provides a foundation for subsequent detailed studies of the creep behavior of ceramic materials under dynamic pressure.

Taking matters into their own hands: How Investors' stock preferences affect mutual fund flows in China

We examine the impact of stock preference of mutual fund's holding on fund flow in China. Our results indicate that mutual funds with an investment style consistent with individual investors' stock preferences have higher fund flow. We find that it affects only individual investors' fund flow, not institutional investors' fund flow. This impact is greater during periods of low economic policy uncertainty or high investor sentiment. Moreover, this impact is reduced if the fund size or age is small. The reasonable theoretical explanation is that investors infer fund managers' skills by analyzing the stocks in the holding portfolio. The results using index funds as the control group further validate this explanation. The novelty of our finding lies in its conflict with the concept of “delegating investment decisions to professionals.” Further analysis reveals there is no correlation between this preference and future returns. Our findings contribute to the study of mutual fund investor behavior from a fresh perspective.

51892 A Comparative Study of Sun Protective Behaviors and Beliefs among Parents of Youth Athletes in Rural and Urban Ohio

51892 A Comparative Study of Sun Protective Behaviors and Beliefs among Parents of Youth Athletes in Rural and Urban Ohio

In-Situ comparative study of photo-induced charge behavior in single-perovskite Cs3Bi2Br9 and double-perovskite Cs2AgBiBr6

While organic-inorganic lead halide perovskites excel in optoelectronic applications, their use is limited by toxicity and degradation. Consequently, lead-free alternatives like Cs2AgBiBr6, offering greater stability and diverse applications, have been investigated. However, the fundamental structural, optical, and electronic properties of Cs2AgBiBr6 remain insufficiently understood. In this study, we compared the exciton dynamics and photo-induced charge separation in Cs3Bi2Br9 and Cs2AgBiBr6 films using in-situ surface techniques. Both materials display similar surface photovoltage (SPV) peaks in the 450–500 nm range, supporting the hypothesis of Bi 6s-6p orbital transitions in distorted [BiBr6]3− structures. Although many theories propose the presence of self-trapped excitons (STE) in bismuth-based perovskites, sufficient evidence has been lacking. Our observation of a significant redshift in the SPV peak compared to the band edge absorption peak supports STE hypothesis, with Cs2AgBiBr6 showing a more pronounced redshift due to its more complex electronic structure and stronger electron-phonon coupling. Additionally, we observed that Cs2AgBiBr6 exhibits superior charge separation efficiency compared to Cs3Bi2Br9. Notably, Cs2AgBiBr6 shows significantly shorter rise times, indicating more rapid photogenerated charge separation. However, both materials exhibit similar fall times, suggesting comparable charge recombination rates. Light-chopping-frequency dependent SPV measurements further reveal that Cs2AgBiBr6 has a higher charge separation rate than Cs3Bi2Br9. These findings underscore the potential of bismuth-based perovskites for optoelectronic applications and highlight the importance of a comprehensive understanding of their structure-property relationships.

Experimental study of foam stability and interfacial behaviour of cellulose nanocrystals-enhanced C22-tailed zwitterionic betaine surfactant

The intrinsic thermodynamic instability of foam systems significantly constrains their effectiveness in enhancing oil and gas recovery from unconventional reservoirs. This study investigated the foam properties and interfacial rheological characteristics of the EDAB/CNC/APG system, analyzing the influence of various factors including temperature, pH, and inorganic salts. The results indicated that the optimal concentration ratio for CNC-surfactant system consists of 0.3 % EDAB, 1.5 % CNC and 0.5 % APG by mass fraction. In this system, the addition of CNC forms a three-dimensional network structure at the gas–liquid continuous interface, significantly extending the drainage half-life of the system. At elevated temperatures, the intense molecular thermal motion disrupts the interactions between CNC and EDAB. This disruption leads to a decrease in surface tension and the viscoelastic modulus of interfacial expansion, resulting in an increase of foam volume but a decline in foam drainage half-life. Foam performance and interfacial rheological characteristics are optimal under neutral pH conditions and manifest higher stability in alkaline conditions compared to acidic conditions. In highly mineralized reservoirs (≥5.0 % salt concentration), inorganic salt ions shield the attraction between CNC and oppositely charged surfactants. This shielding weakens the cross-linking within CNC-surfactant systems, altering the structure of the liquid film interface and causing a sharp decrease in foam half-life. The C22-tailed zwitterionic betaine surfactant EDAB, enhanced by CNC, provides a novel, environmentally friendly, efficient, and safe approach to the exploitation of complex, low-permeability oil and gas reservoirs.

P172 WHAT ARE CONSUMERS’ KNOWLEDGE, ATTITUDES, AND BEHAVIORS RELATED TO REDUCED-SODIUM SALT? A SYSTEMATIC REVIEW

Background and objective: Despite compelling evidence of the efficacy of reduced-sodium salt in lowering blood pressure and cardiovascular disease risk, it is currently an underutilized intervention. To inform the approaches needed to scale-up use of reduced-sodium salt, it is important to understand how it is perceived by consumers. This study systematically assessed consumers’ knowledge, attitudes, and behaviors relating to reduced-sodium salt. Methods: PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL) plus, Cochrane Central Register for Controlled Trials (CENTRAL) and Google Scholar (all years to 8 February 2024) were systematically searched to identify studies reporting quantitative or qualitative outcome measures of knowledge, attitudes, or behaviors related to reduced-sodium salt. Reduced-sodium salt was salt where all or a proportion of sodium chloride is replaced with a non-sodium component. The population of interest included consumers, healthcare professionals and chefs. Results: Twenty-eight studies from 11 countries were included. 17 were evaluations following a reduced-sodium salt intervention and 11 were descriptive studies of knowledge, attitudes, and behaviors in the general population. Intervention studies in China identified high overall acceptability, with medium-to-long-term continued use, ranging from 65 to 83% of participants despite about half reporting adverse taste differences. Rates of reduced-sodium salt use were lower among the general population groups studied (ranging from 10-16%) where interventions such as education and cost subsidization were not used. Descriptive studies without a reduced-sodium salt intervention found lower knowledge and awareness among consumers compared to healthcare professionals. Conclusions: Differences in taste were detectable by many but did not appear to affect overall acceptability of reduced-sodium salts. Increased awareness and knowledge about reduced-sodium salt, particularly among the general population, will be key to scaling the use of reduced-sodium salts.

In-situ study of tensile behavior of Ti/Al laminated metal composites fabricated via ultrasonic additive manufacturing

In this paper, the in-situ tensile behavior of Ti/Al laminated metal composites (LMCs) prepared via ultrasonic additive manufacturing (UAM) was investigated by optical microscopy combined with digital image correlation. Compared with pure Ti foil and Al/Al LMCs processed via UAM, the Ti/Al LMCs exhibit a significantly larger plasticity with intermediate tensile strength. This can be attributed to (ⅰ) strain dispersion in Ti/Al LMCs, (ⅱ) necking inhibiting due to well-bonded interface during early stage of deformation, and (ⅲ) microcracking during late stage of deformation at the rough Ti/Al interfaces, which originate from direct contact between Ti foil and sonotrode.

Preschool-aged children 24-hour movement behaviours before and during COVID-19

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affected health, economies, and lifestyles, but little is known about its impact on children. We aimed to investigate changes in 24-hour (h) movement behaviours of pre-school children before and during COVID-19, and factors that influenced these. Children aged 3–6 years were recruited in Beijing in 2019, and their movement behaviours over 24 ​h assessed by questionnaire, as part of the International Study of Movement Behaviors in the Early Years (SUNRISE) study. We conducted the survey again during COVID-19, and compared the children’s movement behaviours before and during COVID-19 and associated factors. Overall, 196 parents completed the survey at both time points. The percentage of children meeting movement guidelines decreased during the pandemic (p ​< ​0.01). Total physical activity decreased less among children getting good quality sleep or with more adults in the household (p ​< ​0.01). Children who were not cared for primarily by their mother had a greater decrease in moderate to vigorous intensity physical activity (p ​= ​0.02), but the decrease was smaller among children whose parents used the internet to support their physical activity and/or screen time (p ​< ​0.05). Children who used electronic screen devices in the 2 ​h before bedtime or whose parents reported body temperature in webchats had a greater increase in sedentary screen time (p ​< ​0.05). Children spending more time outdoors showed a smaller decrease in sleep (p ​< ​0.01). Overall, children’s movement behaviours changed significantly during the pandemic.

It Helped Push Me Through the Class’: Community College Student Perceptions of the Role of Instructor Immediacy Behaviors in Completing an Online Course

For decades, the number of students enrolling in online courses has been increasing, and this trend toward online education has been further intensified as a result of the COVID-19 pandemic. The completion rate of online courses is not as high as in-person instruction, and researchers and practitioners have long been invested in identifying ways in which online education can be optimized. One dimension of online education that has received scholarly attention is the transactional distance that exists between students and instructors, which, if not appropriately minimized, can lead to a variety of negative student outcomes. Scholars have also identified a variety of verbal and nonverbal immediacy behaviors that can help online instructors decrease this transactional distance and promote a variety of positive student outcomes. To date, the study of immediacy behaviors in online college courses has focused primarily on four-year institutions utilizing quantitative methods. As complement to this research, we interviewed 12 community college students to better understand how a particular set of immediacy behaviors (i.e., a “welcome” phone call, sending personalized emails, using humor, creating videos, and sending “check-in” emails) influenced students’ desire and ability to remain in and complete an online course. Implications of these findings for practice and future research are discussed.

An alternative stress boundary condition in small deformations and its application to soft elastic composites and structures

Linear elasticity theory has been used extensively in the study of the elastic behavior of various perforated structures and composite materials requiring the accompaniment of appropriate boundary conditions to derive qualitatively correct and quantitatively referential solutions. When incorporating conventional boundary conditions, however, linear elasticity theory fails to predict certain essential phenomena associated with perforate structures and composite materials even when they undergo small deformations. For example, a soft elastic porous medium is appreciably stiffened when inflated despite the fact that the internal air pressure is significantly lower than the modulus of the medium itself. In this paper, we propose an improved stress boundary condition by simply incorporating a small change in the normal to the boundary during deformation. We show via numerical examples that in the context of linear elasticity theory, the use of this improved boundary condition offers the possibility of predicting the influence of initial or residual stress in a perforated structure on the elastic response of the structure to external loadings (which can never be captured with the use of conventional boundary conditions). We perform also large-deformation-based finite element simulations to verify the accuracy of the closed-form results obtained from the improved boundary condition for a soft elastic perforated structure with initial internal pressure. We believe that the idea presented in this paper will extend the applicability of linear elasticity theory and yield more accurate referential analytic results for soft elastic structures and composites.

VOF-DEM study of particle entrainment behaviors in the gas–solid-liquid system with multi-inlet configuration

Enhancing the entrainment capability of particles by bubbles is pivotal for facilitating particle elutriation and augmenting reaction efficiency in gas–liquid-solid systems. The current work utilizes the volume of fluid method in conjunction with discrete element method (VOF-DEM) to study particle entrainment in gas–liquid-solid three-phase reactors featuring different gas inlet layouts. Following model validation, this study delves into the multiphase flow characteristics and particle behaviors in detail. The results reveal that the merging of adjacent channels leads to the formation of larger combined bubbles, thereby increasing particle force, velocity, entrainment height, and dissipation coefficient. The average entrainment height during the merging of adjacent bubble channels is 42% higher compared to the four-channel configuration. However, this amalgamation diminishes the channel count and particle entrainment count. Specifically, the highest particle entrainment occurs in the two-channel configuration, which is 26% greater than that in the adjacent-channel merging configuration. Conversely, increasing the channel number decreases bubble size and overall particle entrainment capacity. With consistent bubble sizes, an increase in particle entrainment is associated with reduced entrainment height and dissipation coefficient, indicative of diminished momentum transfer from bubble wakes to individual particles. Additionally, maintaining an optimal number of channels ensures high gas inlet velocity and bubble size, thereby enhancing particle entrainment efficiency. Lastly, appropriately reducing channel distance fosters interaction between adjacent channels, resulting in a meandering bubble path that further promotes particle entrainment and elution efficiency. The results obtained from this study serve as a useful reference for the design and optimization of similar systems.

A comparative study of self-confidence and aggressive behavior between sportsman and non-sportsman

A comparative study of self-confidence and aggressive behavior between sportsman and non-sportsman

Shot peening effects on Cr-Mo-V steel: a comprehensive study of microstructure, surface roughness, residual stress, and mechanical behavior

This study presents a comprehensive study of the microstructure, mechanical characteristics, and surface roughness of Cr-Mo-V low alloy steels and a detailed investigation of the overall impact of shot peening (SP). The microstructure was examined using the optical and scanning electron microscope, showing a significant grain size decrease after shot peening. Evaluations of mechanical characteristics, such as microhardness and tensile strength, showed a noteworthy rise, suggesting enhanced material strength. Studies using fragmentography shed more light on changed fracture tendencies. X-ray diffraction technique (XRD) was used to measure residual stress distribution, and the outcomes displayed an increase after SP, which suggests that internal stresses were created. Surface roughness measurements also showed a noticeable decline, indicating better surface quality. The transformational effects of shot peening on Cr-Mo-V low alloy steels were highlighted by comparative investigations with base metals, providing insights into enhancing material performance for various engineering applications.

Comments on the thermodynamic and dielectric studies on hydrogen-bonded liquid crystal complexes

A research article titled as “Hydrogen-bonded liquid crystal complexes: A comprehensive study of structure, behaviour and potential applications” has been recently published by Meddeb et al., J. Mol. Liq. 395 (2024) 123838. Authors have reported and analysed thermodynamic and dielectric studies on highly ordered SmB and SmG mesophases in 14OBAF/DABCO complexes. But explanations of the dielectric data reported on the material are flawed based on various facts. Unintended wrong interpretations by the authors in reporting and explaining the thermodynamic and dielectric results are discussed here. Influence of various artefacts on acquired dielectric data has also been discussed in order to avoid such problems in further reports.