Experimental Research Articles

Active pendulation control of hoisting systems of ship-mounted cranes under ocean wave excitations: Principle and experimental study

Large-scale ship-mounted cranes are important facilities for marine construction. However, under harsh sea conditions, the hoisting system of a ship-mounted crane is often subjected to wave loadings, leading to frequent occurrences of large-amplitude resonance. This paper proposes an active control method, termed the active displacement compensation (ADC) approach, designed for suppressing the large-amplitude pendulation of the hoisting system of ship-mounted cranes. By controlling the position of the suspension point of the hoisting system using linear-motion actuators, the input excitations of the hoisting system induced by the ship motions can be partially or fully compensated in real-time. Therefore, the proposed ADC approach can significantly suppress the large-amplitude pendulation of the hoisting system. The optimal feedback gain and time delay of the ADC approach are theoretically obtained. The ADC approach has been validated by using a six-degree-of-freedoms shaking table test and numerical simulation on the in-plane pendulation suppression of a small-scale hoisting system. Experimental results indicate that the ADC approach achieves a pendulation reduction ratio between 85 % and 89 % for the hoisting system subjected to scaled ship motion records. This study may help develop efficient active control techniques for hoisting systems of ship-mounted cranes under harsh sea conditions.

Experimental, theoretical and optimization studies on multimode vibration reduction of floating raft system based on NES cells

Most of the studies on multimode vibration reduction of floating raft systems remain at the stage of theoretical analysis, while relevant experimental studies are rare. In this paper, an experimental setup for a scaled-down floating raft system is constructed. The vertical track nonlinear energy sink (TNES) cells are experimentally applied for the first time to suppress the multimode vibration of the floating raft system. To ensure the damping effect is not affected by additional mass, the TNES cells are always installed on the floating raft system. The TNES is able to achieve vibration suppression by allowing unrestricted movement of its vibrator. Two damping systems with different TNESs placement are proposed. Experimental modal analysis is performed on the floating raft structure to determine its response characteristics. Based on the results, different magnitudes of excitation force are applied to each order mode to effectively suppress the multimode vibration of the system. Meanwhile, the nonlinear system coupled with TNES cells is analyzed using the harmonic balance method (HBM) to obtain the approximate analytical solution. The system responses obtained from the analytical solution are compared with the experimental data results. The particle swarm optimization (PSO) algorithm is used to obtain the optimal parameters of the TNESs for vibration suppression. The results show that the multimodal vibration of the floating raft structure is effectively suppressed by the TNES cells in both experimental and theoretical analyses. The vibration suppression effect for all modes is significantly improved by the PSO algorithm. In conclusion, the research content of this paper provides a practical and feasible vibration suppression solution for the design of floating raft systems.

A case study: exploring the impact of 3D printed models on cognitive integration during clinical skills training

Background: Cognitive integration occurs when trainees make conceptual connections between relevant knowledges and is known to improve learning. While several experimental studies have demonstrated how text and audio-visual instruction can be designed to enhance cognitive integration, clinical skills training in real-world contexts may require alternative educational strategies. Introducing three-dimensional (3D) printed models during clinical skills instruction may offer unique learning opportunities to support cognitive integration. Methods: Using case study methodology, we explore how learners and an instructor used 3D printed bones to augment their learning interactions during a clinical skills laboratory on shoulder on palpation, and to describe the instructional strategies with 3D printed bones that may support learning. Students (n = 21) worked in small groups and were given access to a 3D printed clavicle, scapula, and humerus. Data were collected through observation, a student focus group, and a semi-structured interview with the instructor. Thematic analysis to review and code the data and to generate themes. Results: We developed four themes that describe how 3D printed models were used in the classroom and how they may support cognitive integration: classroom interactivity, visualization of anatomy, integrating knowledge, and educational potential. Conclusions: The findings demonstrate several ways 3D printed models can augment how learners, instructors, and educational materials interact with one another and how readily learners make connections between different sources and types of knowledge. This research extends previous work by demonstrating how social learning processes and interactions with physical models can offer unique affordances that may support cognitive integration.

Advanced Computational Methods in Lithium–Sulfur Batteries

AbstractLithium–sulfur (Li–S) batteries, as one of the most promising “post‐Li‐ion” energy storage devices, encounter several intrinsic challenges: polysulfide dissolution and shuttle effect, poor sulfur utilization, lithiation‐induced sulfur expansion, and lithium dendritic growth. These challenges must be resolved, and the associated mechanisms must be completely understood before the practical applications of Li–S batteries. Despite significant progress in enhancing battery capacities, experimental studies on the working mechanisms of Li–S batteries remain challenging. Alternatively, computational methods are proven useful for understanding Li–S electrochemistry and designing high‐performance Li–S batteries. This review presents recent advances in computational methods (density functional theory, molecular dynamics simulations, and finite element analysis) for Li–S batteries, compares their advantages, and summarizes their favorable applications in addressing the challenges of Li–S batteries. Computational methods should find more applications in the development of Li–S batteries.

Magnetic nanoparticles of TiO2-NiFe2O4-Chitosan for photocatalytic degradation: synthesis, characterization, methyl blue dye - VOCs wastewater treatment, kinetic experimental, and theoretical studies

Magnetic nanoparticles of TiO2-NiFe2O4-Chitosan for photocatalytic degradation: synthesis, characterization, methyl blue dye - VOCs wastewater treatment, kinetic experimental, and theoretical studies

Using expansive learning to design and implement video-annotated peer feedback in an undergraduate general education module

AbstractExisting studies have measured the effect of video-based feedback on student performance or satisfaction. Other issues are underacknowledged or merit further investigation. These include sociocultural aspects which may shape the design and implementation of video-based feedback, the ways students use technology to engage in feedback, and the processes through technology may transform learning. This study investigates the design and implementation of a video-annotated peer feedback activity to develop students’ presentation skills and knowledge of climate science. It explores how their use of a video annotation tool re-mediated established feedback practices and how the systematic analysis of contradictions in emerging practices informed the subsequent redesign and reimplementation of the approach. Employing a formative intervention design, the researchers intervened in the activity system of a first-year undergraduate education module to facilitate two cycles of expansive learning with an instructor and two groups of Hong Kong Chinese students (n = 97, n = 94) across two semesters. Instructor interviews, student surveys, and video annotation and system data were analysed using Activity Theory-derived criteria to highlight contradictions in each system and suggest how these could be overcome. The findings highlight the critical importance of active instructor facilitation; building student motivation by embedding social-affective support and positioning peer feedback as an integrated, formative process; and supporting students’ use of appropriate cognitive scaffolding to encourage their interactive, efficient use of the annotation tool. Conclusions: In a field dominated by experimental and quasi-experimental studies, this study reveals how an Activity Theory-derived research design and framework can be used to systemically analyse cycles of design and implementation of video-annotated peer feedback. It also suggests how the new activity system might be consolidated and generalised.

Decreased activity in zebrafish larvae exposed to glyphosate-based herbicides during development—potential mediation by glucocorticoid receptor

Glyphosate-based herbicides (GBH) are a widely used group of pesticides that have glyphosate (GLY) as main active compound and are used to control a wide range of weeds. Experimental and epidemiological studies point to neurotoxicity and endocrine disruption as main toxic effects. The aim of this study was to investigate the effects of developmental exposure to GLY and GBH on locomotor behavior, and the possible contribution of GR-mediated signaling. We used zebrafish (Danio rerio) larvae in a continuous exposure regimen to GLY or GBH in the rearing medium. Alongside TL wildtype, we used a mutant line carrying a mutation in the GR which prevents the GR from binding to DNA (grs357), as well as a transgenic strain expressing a variant of enhanced green fluorescent protein (d4eGFP) controlled by a promoter carrying multiple GR response elements (SR4G). We found that acute exposure to GBH, but not GLY, activates GR-mediated signaling. Using a continuous developmental exposure regime, we show that wildtype larvae exposed to GBH display decreased spontaneous activity and attenuated response to environmental stimuli, a pattern of alteration similar to the one observed in grs357 mutant larvae. In addition, developmental exposure to GBH has virtually no effects on the behavior of grs357 mutant larvae. Taken together, our data indicate that developmental exposure to GBH has more pronounced effects than GLY on behavior at 5 dpf, and that interference with GR-mediated signaling may have a relevant contribution.

An experimental and numerical study of propyl acetate laminar combustion characteristics

The laminar burning characteristics of propyl acetate were investigated using the constant volume combustion experimental unit at the working conditions of 1, 2, and 4 bar and 390, 420, and 450 K over a wide range of equivalence ratios (0.7–1.4). Both experimental and numerical investigations were used to study the laminar combustion characteristics of propyl acetate. Also, a chemical mechanism was proposed in this work to numerically investigate the laminar combustion of propyl acetate. A comparison of this study and literature experimental burning velocity data with the proposed mechanism laminar burning velocity showed satisfactory agreement. Sensitivity investigations of the burning velocity and production rate analysis of the reactions revealed that the reaction that mostly produces OH, H, and O radicals significantly drives the combustion of propyl acetate and increases the laminar burning velocity. Moreover, fuel-related reaction R1086: H + PA ⇔ H2 + PA2J increased the laminar burning velocity but fuel-related reaction R1098: OH + PA ⇔ H2O + PAMJ decreased the burning velocity. The reaction pathway study showed that propyl acetate mainly decomposes to PAMJ radical, PA2J radical, PAEJ radical, propene, and acetic acid before it converts into other radicals. Also, it was shown that ally radicals and ketene are essential intermediates in the fuel conversion process of propyl acetate.

On the intrusiveness of phosphor thermometry for metal surface temperature measurements in reciprocating engines: An experimental and heat conduction modeling study

Abstract Lifetime-based phosphor thermometry has been applied in a wide variety of surface temperature measurement applications due to its relative ease of implementation and robustness to background interference when compared to other optical temperature measurement methods. It is often assumed that the technique is minimally intrusive if the thickness of the applied phosphor coating is < 20 µm. To evaluate this assumption, high-speed phosphor surface temperature and thermocouple measurements were performed on 4140 steel substrates installed in the cylinder head of an optically-accessible internal-combustion engine for four operating conditions. For phosphor thermometry measurements, four substrates were studied, each coated with a phosphor layer of different thickness ranging between 6 µm and 47 µm. The phosphor thermometry measured temperature swings during combustion were shown to be heavily impacted by the presence of the phosphor coatings, increasing by roughly a factor of 2 - 2.5 when increasing the thickness from 6 µm to 30 µm. A technique was implemented which utilizes the temperature data in combination with a heat conduction model to provide estimates of the temperature swing and heat transfer flux in the absence of the phosphor coating. It was shown that even the 6 µm phosphor coating could lead to an order of magnitude increase in the temperature swing relative to the uncoated 4140 steel substrate. Despite the intrusiveness of phosphor thermometry for the surface temperature measurements, reasonable agreement was demonstrated between heat flux estimates determined with the heat transfer modeling technique and those deduced from temperature-swing measurements using two different high-speed thermocouples. The results indicate that phosphor surface thermometry can be a reliable surface temperature and heat flux diagnostic for transient high heat flux environments, as long as proper care is taken to account for the impact of the phosphor layer on the measurement.

Microwave-assisted fabrication of high-strength natural fiber hybrid composites for sustainable applications: An experimental and computational study

The present study deals with the fabrication of hybrid composites using biodegradable and ecologically friendly natural fibers and a recyclable thermoplastic matrix. Pure and hybrid natural fiber composites of high-density polyethylene (HDPE) with Kenaf and Ramie fiber, 20 wt%, were fabricated using microwave-assisted compression molding. The composite's mechanical characterization was performed using tensile, flexural, impact, and hardness tests. X-ray diffraction was done to investigate the crystallinity percentage, and scanning electron microscopy of fractured surfaces was performed to determine failure mechanisms. The hybrid composite of HDPE/Ramie and Kenaf exhibited the highest ultimate tensile strength (UTS) at 29.3 ± 1.2 MPa, surpassing HDPE/Kenaf (21.6 ± 1.1 MPa) and HDPE/Ramie (24.3 ± 1.4 MPa) composites. In terms of flexural strength, HDPE/Ramie demonstrated the highest at 19.9 ± 1.5 MPa, while HDPE/Kenaf had the lowest at 18 ± 1.1 MPa. The hybrid composite's flexural strength was intermediate at 19 ± 1.3 MPa. Impact strength followed a similar trend, with the hybrid composite leading at 40.2 KJ/m2, followed by HDPE/Ramie (26.9 KJ/m2) and HDPE/Kenaf (12.3 KJ/m2). Hardness tests revealed the highest hardness in the hybrid composite and the lowest in HDPE/Kenaf. A computational study has been performed to develop a model for predicting the hybrid composites. A strong agreement between both studies has been observed. The developed composite is deemed suitable for various light-duty applications, such as roofing, car interior panels, and mobile covers, offering potential benefits in reducing carbon footprint.

Experimental and Theoretical Study on the Shear Performance of Single-Box Double-Compartment Segmental Box Girder

Experimental and Theoretical Study on the Shear Performance of Single-Box Double-Compartment Segmental Box Girder

Investigation of the discharge coefficient for laidback fan-shaped holes on turbine blades under internal crossflow condition

Abstract The discharge coefficient of laidback fan-shaped holes on turbine blades is investigated using experimental and numerical simulation methods. The study is conducted on a linear cascade, with single rows of film holes set on both the pressure and suction surfaces of the test blade, coolant supplied by an internal crossflow channel. The crossflow Reynolds number ranged from 39100 to 78200, and the pressure ratio ranged from 1 to 1.5. This research considered the effects of crossflow Reynolds numbers, hole length-to-diameter ratio, and hole row position on the discharge coefficient of film holes. The findings are as follows: internal crossflow increases the inlet loss of film holes and flow separation within holes, leading to a significant reduction in the discharge coefficient of film holes. Meanwhile, film holes on the pressure surface of the blade exhibit greater sensitivity to crossflow. Under different hole length-to-diameter ratio conditions, the length of the cylindrical section is the primary factor affecting the discharge coefficient, the magnitude of the discharge coefficient depended on the extent of flow separation within the cylindrical section. The sensitivity of the discharge coefficient to variations in the cylindrical section length decreases once cylindrical section length exceeds 2.8D for the pressure surface and 2.0D for the suction surface, where the inlet separation region reattaches to the wall. The hole row positioning has a significant impact on the discharge coefficient in the plenum condition, especially under conditions where the pressure ratio is less than 1.05.

Study on the promotion multiple of blood flow velocity on human epidermal microcirculation of volcanic rock polymer fiber seamless knitted fabric

Abstract As a material that can release infrared rays, volcanic rock polymer fibers can be used in textiles to improve human microcirculation, which is helpful to relieve chronic inflammatory diseases such as perishoulder arthritis. In this article, there are two different kinds of exterior yarns. Volcanic rock blended polyester, volcanic rock blended polyamide, polyester and polyamide are chosen as the material type of exterior yarn Ⅰ, whereas the material type of exterior yarn II is conductive polyamide yarn. The exterior yarn feed ratio of exterior yarn Ⅰ and exterior yarn II is designed as 8:0, 7:1 and 6:2 when weft plain stitch, 1 + 1 mock rib and 1 + 3 mock rib are used as the knitted structure of the fabric. According to the three-factor four-level orthogonal experimental design method, the sample protocol was established, and 16 knitted sample fabrics were produced. Then, the promotion multiple of blood flow velocity on human epidermal microcirculation of each sample was tested and analyzed. The results show that the promotion multiple of blood flow velocity on human epidermal microcirculation of the fabrics woven by volcanic rock polymer fibers is better than that of the blank control group, and the difference between fabrics with different volcanic rock polymer fibers is small. The higher the proportion of exterior yarn Ⅰ is, the better the promotion multiple of blood flow velocity on human epidermal microcirculation of fabric will be. The effect of knitted structure on the promotion multiple of blood flow velocity on human epidermal microcirculation of fabrics is not obvious. This study provides reference for the design of medical or health textiles for chronic inflammatory diseases.

Augmented reality in environmental education: A systematic review

Digital technologies are opening up new ways to involve students in environmental education (EE). Augmented reality (AR) is one of these technologies and can potentially engage students and improve their learning outcomes. In this article, we systematically analyze the use of AR in EE. We searched the ERIC, Scopus, and Web of Science databases for articles related to AR and found 20 articles that met the inclusion and exclusion criteria of the research question. The results showed that most articles examined were published after 2017, and the researchers used experimental research methods. The results also showed that the research participants were mostly primary school students, and the most common sample size was between 50 and 100. In addition, the results revealed four categories: (1) contribution to student learning, (2) affective outcomes, (3) interaction, and (4) other benefits and advantages. We also found that only two articles reported the challenges of using AR in EE. In light of the findings, we recommend suggestions for future studies.

Interfacial Enrichment of Lauric Acid Assisted by Long-Chain Fatty Acids, Acidity and Salinity at Sea Spray Aerosol Surfaces.

Surfactant monolayers at sea spray aerosol (SSA) surfaces regulate various atmospheric processes including gas transfer, cloud interactions, and radiative properties. Most experimental studies of SSA employ a simplified surfactant mixture of long-chain fatty acids (LCFAs) as a proxy for the sea surface microlayer or SSA surface. However, medium-chain fatty acids (MCFAs) make up nearly 30% of the FA fraction in nascent SSA. Given that LCFA monolayers are easily disrupted upon the introduction of chemical heterogeneity (such as mixed chain lengths), simple FA proxies are unlikely to represent realistic SSA interfaces. Integrating experimental and computational techniques, we characterize the impact that partially soluble MCFAs have on the properties of atmospherically relevant LCFA mixtures. We explore the extent to which the MCFA lauric acid (LA) is surface stabilized by varying acidity, salinity, and monolayer composition. We also discuss the impacts of pH on LCFA-assisted LA retention, where the presence of LCFAs may shift the surface-adsorption equilibria of laurate─the conjugate base─toward higher surface activities. Molecular dynamic simulations suggest a mechanism for the enhanced surface retention of laurate. We conclude that increased FA heterogeneity at SSA surfaces promotes surface activity of soluble FA species, altering monolayer phase behavior and impacting climate-relevant atmospheric processes.

The Efficacy of the Sensorimotor Training Program on Sensorimotor Development, Auditory and Visual Skills of Schoolchildren Aged 5–8 Years

Abstract Background Around 800 million young children worldwide have cognitive-developmental limitations due to issues related to biological, environmental, and psychosocial factors. These problems lead to educational challenges, limited skill development, and higher unemployment rates. Therefore, timely interventions addressing the underlying problems in institutional settings are critically important. Objective The authors created the “Sensorimotor Training Program” (STP) as a critical intervention to develop skills essential for starting school. This experimental study aimed to investigate the impact of the STP in an institutional setting, targeting the specific auditory and visual skills crucial for kindergarten and primary school learning. Methods The STP comprises 120 training sessions focused on sensorimotor maturation. Seven hundred and seventy-two children aged 5–8 participated in the study, with 704 in the experimental and 68 in the control group, each containing a relatively balanced ratio of boys to girls. The study spanned six to eight months, with three to five weekly sessions. Results The intervention resulted in significant improvements in sensorimotor development in the experimental compared to the control group [p < .001, effect size (d) = .483; auditory skills r = .605 p < .001, d = .366; visual skills r = .542, p < .001, d = .294]. The intervention group also improved compared to its baseline measurements. Conclusion These results show that implementing the STP in school settings can improve sensorimotor development, impacting auditory and visual skills in children aged 5–8. These intervention-based improvements are above and beyond biological maturation.

Mechanism and experimental study of in situ metallization on the surface of silver ion conductive glass

AbstractIn situ metallization of Ag+ conductive glass was successfully achieved by applying electric and temperature fields to the glass to ensure the controlled migration of ions inside the glass. The transport and kinetic characteristics of Ag+ under the combined effect of electric field and temperature field were investigated by calculating and analyzing Ag+ diffusion coefficient. The correlations between ion transport and current were characterized with potential energy equations. The simulations and experiments of ion transport in the conducting glass were implemented, which revealed the mechanisms of ion transport and interfacial precipitation within the conducting glass. Further more, the existence of Ag+ deprivation layer was confirmed and it was clarified that the depth of the deprivation layer reached 30 µm under thermal polarization conditions of 60 V and 300°C. The microscopic morphology of in situ silver deposition layer was observed using SEM and TOF–SIMS. In addition, It was determined that the in situ metallization of conductive glass under the polarization condition of 60 V at 250°C was the best, and the thickness of deposited silver dendrites reached 1000 nm in the side of cathodically. This paper provides theoretical and experimental references for the optimization of the in situ metallization process for the ion conductive glass.

The effect of shortfin mako shark skin at the reattachment of a separated turbulent boundary layer

This smooth flat experimental study investigates the capability of mako shark scales to control flow separation when placed downstream of the onset of turbulent boundary layer separation and within the reattachment region. The objective of the study is to validate the hypothesis that the shark scales' bristling and recoiling would prevent the flow separation on the flank region (the fastest flow region) of the shark. A rotating cylinder was used to induce an adverse pressure gradient over a flat plate to produce a region of separated flow where the shark skin specimen was mounted. Two types of mako shark scales (flank (B2) and between flank and dorsal fin (B1)) were positioned in the preferred flow direction on a flat plate. The B2 scales are slender, 200μm tall, and can bristle up to 50°. In contrast, B1 scales are wider, shorter, and can bristle at 30°. The bristling angle and shape are the main mechanisms by which the scales act to inhibit flow from moving upstream near the wall. Thus, the difference in the bristling angles and structures of the scales is attributed to the fact that the B2 scales function in a thicker boundary layer (behind the shark's gills) where they must bristle sufficiently high into the boundary layer to control the flow separation, and because the adverse pressure gradient in this region is higher where flow separation is more likely. The scales are placed in the reattachment region to elucidate their ability to control and reattach an already separated turbulent flow. The results show that B2 scales placed in the reattachment region reduce the size of the turbulent separation bubble and decrease the turbulent kinetic energy, while B1 scales have the opposite effect.

Dielectrophoretic Direct Assembling of MXene Flakes at the Level of Screen-Printed Interdigitated Microelectrodes and their Evaluation in Gas Sensing Applications

Abstract Controlling, orientating, and assembling 2D materials is critical for their successful exploitation as active elements in various applications, particularly for sensors. Despite the increased interest in exploiting the properties of MXenes, to date, the direct assembly of this category of materials based on an electric field has not been reported. Thus, this work presents an experimental study on dielectrophoretic assembly of pristine MXene flakes at the level of screen-printed interdigitated microelectrodes. The development of MXene uniaxial "bridges" across electrode micro-gaps can be controlled by convenient dielectrophoretic parameters such as voltage and frequency, which are thoroughly discussed. Moreover, appropriate frequencies for avoiding parasitic electrokinetic phenomena (AC electro-osmosis, electrothermal effect) that hamper the application of dielectrophoresis were identified. Finally, the proposed methodology for assembling MXene flakes demonstrates its feasibility of being used for development of chemiresistors as of satisfactory response of pristine MXene “bridges” to ethanol atmosphere.

Numerical and Experimental Study of Flow-Induced Vibrations in Micro-Tube Heat Exchangers

Abstract Thermal management presents an increasing challenge in future engineering systems, especially in applications like combined cycle precooling, waste heat recovery, and innovative propulsion systems. These systems face a growing demand for managing higher heat loads while coping with limited heat sink. Central to these thermal management systems is the heat exchanger, with micro-tube heat transfer emerging as a promising solution for future technologies. Micro-tube heat exchangers are becoming popular owing to their ability to significantly enhance the heat transfer surface area while maintaining a compact core volume. As the demand for high-performance, lightweight heat exchangers escalates, micro-tube heat exchangers are being designed to be increasingly compact yet highly loaded. This trend poses significant challenges to their structural integrity, particularly under harsh operational conditions. Flow-induced vibrations, a critical concern in the design of tubular heat exchangers, can lead to tube failures, compromising the safe operation of engineering systems. While the flow-induced vibrations of conventional-sized heat exchangers have been extensively studied, there is a noticeable gap in the research on similar phenomena in micro-tube heat exchangers. This paper details ongoing research at Reaction Engines Ltd to aid the design of safe and robust heat exchangers, focusing on the flow-induced vibrations in micro-tube heat exchangers and utilizing a cutting-edge laser vibrometry test facility. A predictive model, employing an unsteady flow simulation approach and eigenvalue analysis, has been formulated.