Search

Recently, we presented a method to assign atomic partial charges based on the DASH (dynamic attention-based substructure hierarchy) tree with high efficiency and quantum mechanical (QM)-like accuracy. In addition, the approach can be considered "rule based"—where the rules are derived from the attention values of a graph neural network—and thus, each assignment is fully explainable by visualizing the underlying molecular substructures. In this work, we demonstrate that these hierarchically sorted substructures capture the key features of the local environment of an atom and allow us to predict different atomic properties with high accuracy without building a new DASH tree for each property. The fast prediction of atomic properties in molecules with the DASH tree can, for example, be used as an efficient way to generate feature vectors for machine learning without the need for expensive QM calculations. The final DASH tree with the different atomic properties as well as the complete dataset with wave functions is made freely available. [ABSTRACT FROM AUTHOR]

To establish a universal and convenient mathematical model for predicting static and dynamic performance of composite sandwich structures, a novel three-dimensional equivalent homogenized model (3D-EHM) is proposed based on variational asymptotic method. The multiscale mechanical analysis of composite hexagonal and re-entrant honeycomb sandwich structures is conducted by 3D-EHM, enabling reasonable transmission of mechanical information at different scales and facilitating accurate predictions of mechanical responses in sandwich structures. The comparison analysis with 3D printing experimental results and 3D finite element model results demonstrates that the 3D-EHM exhibits remarkable precision and computational efficiency in forecasting static displacement distributions and higher-order vibration modes, eliminating the need for time-consuming and expensive experiments. Moreover, the effects of the ply angle of the face sheet and core geometric parameters on the effective properties of composite hexagonal honeycomb sandwich structures are systematically investigated. In summary, 3D-EHM is an effective applied mathematical model for designing and analyzing composite sandwich structures, fully combining the systematicity of variational methods and the asymptotic convergence of asymptotic methods. • A novel three-dimensional equivalent homogenized model (3D-EHM) is proposed. • Calculation accuracy and efficiency in predicting mechanical response are high. • Intrinsic connection between microstructure and macroscopic properties is captured. • 3D-EHM facilitates the tailoring and optimization of the sandwich structure. [ABSTRACT FROM AUTHOR]

In terms of the interplay between manufacturing cost and quality during the molding of fiber reinforced thermosetting composites, this study proposes a multi‐scale collaborative optimization strategy aimed at shortening molding time and reducing the diminishing defects generated during the process. Macro‐scale thermochemical and micro‐scale thermomechanical calculations are conducted on the composite molding to analyze the origins of temperature gradients and residual stresses. Then, the curing cycle, temperature gradient in the macro‐scale model, and residual stresses in the micro‐scale model are optimized by combining finite element analysis with the Non‐dominated Sorting Genetic Algorithm II. Several curing processes within the Pareto front were selected, and their impact on compressive performance was assessed through experimental analysis. Compared to the standard curing process (SCP), the optimal curing process exhibited a 41.4% reduction in maximum temperature gradient (∆Tmax), a 25.2% decrease in effective residual stress σ¯, and a 20.0% increase in compressive strength. Multi‐scale collaborative optimization strategies are integral to the advancement of production and application of fiber‐reinforced thermoset composites. Multi‐scale collaborative optimization strategies are integral to the advancement of production and application of fiber‐reinforced thermoset composites. Highlights: Investigated of interactions among components in composites molding.Optimization of composite molding process with Non‐dominated Sorting Genetic Algorithm II and finite element.Examined the impact of composite molding process on compressive performance. [ABSTRACT FROM AUTHOR]

Biomimetic actuation technologies with high muscle strokes, cycle rates, and work capacities are necessary for robotic systems. We present a muscle type that operates based on changes in muscle stiffness caused by volume expansion. This muscle is created by coiling a mechanically strong braid, in which an elastomer hollow tube is adhesively attached inside. We show that the muscle reversibly contracts by 47.3% when driven by an oscillating input air pressure of 120 kilopascals at 10 Hz. It generates a maximum power density of 3.0 W/g and demonstrates a mechanical contractile efficiency of 74%. The muscle's low-pressure operation allowed for portable, thermal pneumatical actuation. Moreover, the muscle demonstrated bipolar actuation, wherein internal pressure leads to muscle length expansion if the initial muscle length is compressed and contraction if the muscle is not compressed. Modeling indicates that muscle expansion significantly alters its stiffness, which causes muscle actuation. We demonstrate the utility of BCMs for fast running and climbing robots. [ABSTRACT FROM AUTHOR]

Bio-mediated methods, such as microbially induced carbonate precipitation, are promising techniques for soil stabilisation. However, uncertainty about the spatial distribution of the minerals formed and the mechanical improvements impedes bio-mediated methods from being translated widely into practice. To bolster confidence in bio-treatment, non-destructive characterisation is desired. Seismic methods offer the possibility to monitor the effectiveness and mechanical efficiency of bio-treatment both in the laboratory and in the field. To aid the interpretation of shear wave velocity measurements, this study uses the discrete element method to examine the small-strain stiffness of bio-cemented sands. Bio-cemented specimens with different characteristics, including properties of the host sand (void ratio, uniformity of particle size distribution) and properties of the precipitated minerals (distribution pattern, content, Young's modulus), are modelled and subjected to static probing. The mechanisms affecting the small-strain properties of cemented soils are investigated from microscopic observations. The results identify two mechanisms controlling the mechanical reinforcement associated with bio-cementation, namely the number of effective bonds and the ability of a single bond to improve stiffness. The results show that the dominant mechanism varies with the properties of the host sand. These results support the use of seismic measurements to assess the mechanical efficiency and effectiveness of bio-mediated treatment. [ABSTRACT FROM AUTHOR]

This study aims to analyze the effect of 70-30 Cu-Ni filler metal on mechanical and microstructural properties of Al 2024 and stainless steel 304 hybrid joints fabricated through the gas tungsten arc welding technique. The mechanical properties, i.e., tensile strength and microhardness, of Al-SS joints have been analyzed and evaluated through joint interfacial microstructure analysis. The optimum tensile strength (155.746 MPa) has been obtained at welding current ranges between 75 and 80 A, welding speed of 110–115 mm/min, and gas flow rate of 9.75-10 L/min, whereas maximum microhardness (300 HV) at welding speed of 115-120 mm/min, welding current of 70-75 A, and gas flow rate of 9.5-10 L/min. The fine equiaxed dendrites at the interface of the aluminum weld zone and the thin interfacial layer at the SS304 weld zone interface contributed to the higher tensile strength. Scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction reveal the ductile CuAl, NiAl3, and NiAl phases instead of Fe-Al brittle phase, improving hybrid bonding between Al 2024 and SS 304. The dimples and tear ridges microstructure have been observed for high-strength joint, while cracks and cavities on the fracture surface indicate its brittleness and low strength (102 MPa). [ABSTRACT FROM AUTHOR]

Abstract\nIMPLICATIONS FOR REHABILITATIONThe gross mechanical efficiency of the manual wheelchair propulsion movement is particularly low compared to other movements. The energy losses in the manual wheelchair propulsion movement are partly due to energy losses associated with the wheelchair, and especially to the rolling resistance of the wheels. The distribution of mass between the front rear wheels and the caster wheels has a significant impact on the rolling resistance. The study of the caster wheels cannot therefore be neglected due to their involvement in rolling resistance. Thus, this study aimed to evaluate the power dissipated due to rolling resistance by different caster wheels, at different speeds and under different loadings on various terrains. Four caster wheels of different shapes, diameters, and materials were tested on two surfaces representative of indoor sports surfaces at four different speeds and under four loadings. The results showed a minimal dissipated power of 0.4±0.2W for the skate caster, on the parquet, at 0.5 m/s and under a loading of 50 N. The maximal mean power dissipated was 43.3±27.6W still for the skate caster, but on the Taraflex, at 1.5 m/s and under loading of 200 N. The power dissipated on the parquet was lower than the one on the Taraflex. The Spherical and Omniwheel caster wheels dissipated less power than the two other casters. This study showed that caster wheels cannot be neglected in the assessment of gross mechanical efficiency, particularly in light of the power dissipated by athletes during propulsion.Highlights the importance of choosing the right front casters depending on the conditions of use of the manual wheelchair.First study to evaluate power dissipation due to rolling resistance in front casters during wheelchair propulsion.Shows that a Taraflex type floor is not suitable for wheelchair sports performance and injury prevention purposes and lower musculoskeletal constraints with equivalent performance.Highlights the importance of choosing the right front casters depending on the conditions of use of the manual wheelchair.First study to evaluate power dissipation due to rolling resistance in front casters during wheelchair propulsion.Shows that a Taraflex type floor is not suitable for wheelchair sports performance and injury prevention purposes and lower musculoskeletal constraints with equivalent performance. [ABSTRACT FROM AUTHOR]

Polymer-based self-lubricating materials are designed to improve the efficiency and reliability of mechanical systems, reducing energy consumption and material loss. Herein, inspired by the texture of the smooth leaf surface, the polyether ether ketone was first subjected to a sulfonation treatment before the plant texture was introduced to the surface of the sulfonated polyether ether ketone (SPEEK) films. The optical microscopy results indicate the successful construction of different bionic textures on SPEEK film surface. Based on the reduction in the contact area between the friction pairs, and the accommodation of abrasive debris by the uneven bionic textures, the tribological performance of SPEEK films under dry friction conditions shows unique advantages. Additionally, the wear morphology and self-lubrication mechanism of bionic textured films were investigated by 3D profilometry, SEM, and XPS. The results show that under the effect of frictional heat and frictional force, the bionic texture morphology changes to fish scale, which reduces the resistance to friction, resulting in a lower friction coefficient and wear rate. This strategy of constructing bionic textures on functional polymer surfaces using a facile process provides a reference for exploring novel self-lubricating materials. [ABSTRACT FROM AUTHOR]

DNA hydrogels hold significant promise for biomedical applications and can be synthesized through enzymatic Rolling Circle Amplification (RCA). Due to the exploratory nature of this emerging field, standardized RCA protocols specifying the impact of reaction parameters are currently lacking. This study varied template sequences and reagent concentrations, evaluating RCA synthesis efficiency and hydrogel mechanical properties through quantitative PCR (qPCR) and indentation measurements, respectively. Primer concentration and stabilizing additives showed minimal impact on RCA efficiency, while changes in polymerase and nucleotide concentrations had a stronger effect. Concentration of the circular template exerted the greatest influence on RCA productivity. An exponential correlation between hydrogel viscosity and DNA amplicon concentration was observed, with nucleobase sequence significantly affecting both amplification efficiency and material properties, particularly through secondary structures. This study suggests that combining high‐throughput experimental methods with structural folding prediction offers a viable approach for systematically establishing structure‐property relationships, aiding the rational design of DNA hydrogel material systems. [ABSTRACT FROM AUTHOR]

This study aimed to improve the design of an automatically controlled sail wind power station (SWPS). The peculiarity of the considered SWPS design is that its working body (WB) is rigidly connected to the upper platform of a Sholkor parallel manipulator that has six degrees of freedom. Six actuators connect the manipulator's upper platform to the fixed lower platform. Each actuator is multifunctional and converts mechanical energy from wind action into electrical energy while controlling the WB's movements. This wind energy conversion, by which the SWPS's structural efficiency is evaluated, largely depends on the actuator's coefficient of performance (CP). To meet the study objective, a prototype actuator was experimentally investigated to establish its efficiency. For this, a new experimental methodology was proposed, which involved sequentially experimenting on wind characteristics to obtain data, establishing a database, processing and preparing the initial data, and conducting a force analysis of the SWPS. Based thereon, the predicted power of the input load on the actuators was determined using Mathcad software. In the experimental setup, this predicted power was used as the actuator's input, and the experimental value of the generated electrical energy (the output power) gave the actuator prototype's efficiency. The actuator's average experimental CP was η― = 0.56−0.58, which demonstrates that this geometry's dimensions and parameters are acceptable. The results of the study will be used to improve the design. The article emphasizes the potential of SWPSs for producing wind energy. [ABSTRACT FROM AUTHOR]

There has been an intense surge in interest in the search for alternative sources of petroleum fuels in the modern world as a result of the inflation of fuel prices and the historic supply gap. When compared to petroleum fuels, biodiesel is becoming an increasingly valuable option due to the fact that it produces less emissions and provides the almost same amount of energy. In point of fact, the prime aim of this work is to explore the possibility of utilizing biodiesel derived from lemongrass oil and including dibutyl ether as an additive for the test diesel engine operating on varied compression ratios. The findings showed that the best operating settings are a 17.5 compression ratio with a blend of 30% biodiesel and 70% diesel fuel. At greater loads, brake thermal efficiency is lower than that of diesel engines. Lower loads result in lower specific fuel usage. Mechanical efficiency at higher loads is highest in the B30 blend, but emission metrics such as CO, CO2, HC, and NOx were reduced with the inclusion of an additive, though HC rose with higher loads of lemongrass oil biodiesel blends. When compared to the B30 biodiesel blend with various composition additives, the B30 + 4% additive has the highest efficiency at the fourth load in terms of both brake power and mechanical efficiency. [ABSTRACT FROM AUTHOR]

As a critical component in mechanical systems, the operational status of rolling bearings plays a pivotal role in ensuring the stability and safety of the entire system. However, in practical applications, the fault diagnosis of rolling bearings often encounters limitations due to the constraint of sample size, leading to suboptimal diagnostic accuracy. This article proposes a rolling bearing fault diagnosis method based on an improved denoising diffusion probability model (DDPM) to address this issue. The practical value of this research lies in its ability to address the limitation of small sample sizes in rolling bearing fault diagnosis. By leveraging DDPM to generate one-dimensional vibration data, the proposed method significantly enriches the datasets and consequently enhances the generalization capability of the diagnostic model. During the model training process, we innovatively introduce the feature differences between the original vibration data and the predicted vibration data generated based on prediction noise into the loss function, making the generated data more directional and targeted. In addition, this article adopts a one-dimensional convolutional neural network (1D-CNN) to construct a fault diagnosis model to more accurately extract and focus on key feature information related to faults. The experimental results show that this method can effectively improve the accuracy and reliability of rolling bearing fault diagnosis, providing new ideas and methods for fault detection and prevention in industrial applications. This advancement in diagnostic technology has the potential to significantly reduce the risk of system failures, enhance operational efficiency, and lower maintenance costs, thus contributing significantly to the safety and efficiency of mechanical systems. [ABSTRACT FROM AUTHOR]

In this study, a novel multifunctional film known as susceptor, containing silver nanoparticles, was proposed to improve the induction welding performance of unidirectional carbon fiber-reinforced polyetherketoneketone (CF/PEKK) thermoplastic composites. A group of Ag/PEKK films was synthesized with different amounts of silver nanoparticles. Good thermal performance was obtained, including the maximum temperature and thermal growth time constant, leading to the selection of films with 60 wt.% and 70 wt.% silver nanoparticles. In addition, the mechanical performance was evaluated for single-lap joints fabricated with the selected films and stainless-steel mesh. Specifically, the highest interlaminar shear strength and single-lap shear strength of 25.2 MPa and 20.9 MPa, respectively, were achieved with a susceptor containing 60 wt.% silver nanoparticles. The mechanism of these increases in thermal and mechanical performance is discussed using numerical and experimental methods (non-destructive test and optical microscope observation). In conclusion, the multifunctional heating film incorporated into the adhesive can improve the thermal and mechanical efficiency of single-lap joints of thermoplastic composites fabricated using the induction welding method. [ABSTRACT FROM AUTHOR]

Current trends in agricultural intensification lead to degraded grasslands, requiring their restoration through native species reintroduction. Various techniques are available for harvesting seeds from donor sites. However, little is known about their performance in South American C3/C4 mixed grasslands, where studies are scarce. Their particular species composition and phenology, with different flowering periods, require specific harvest strategies. We evaluated mechanical seed harvest in a northern Uruguay grassland, part of Río de la Plata grasslands. Performance of two mechanical harvest methods (seed‐stripper and dry hay) was compared in two harvest seasons (late‐spring and mid‐summer). The evaluation considered the quantity and identity of harvested seeds, and their germination in a greenhouse. Hand collections were made to assess standing seed yield. For each seed mixture, efficiency of mechanical harvests (number of seeds and seedlings compared to hand collection), proportion of germinated seeds, species transfer relative to donor site, and composition were calculated. Results revealed trade‐offs between harvests: seed‐stripper in late‐spring presented low seed collection efficiency (2% for seeds, 5% for seedlings) and species richness (43% transfer), but high seed germination (64%), showing selectivity toward winter species; seed‐stripper in mid‐summer and dry hay in both seasons showed high seed collection efficiency (42–154% for seeds, 26–50% for seedlings) and species richness (65–80% transfer), resembling donor site, albeit lower seed germination (9–20%). Seed‐stripper performance varied between seasons, while dry hay remained consistently effective. These results are pioneering for grassland restoration in Uruguay, encouraging future studies to focus on establishment in the field. [ABSTRACT FROM AUTHOR]

In the development of composite solid propellants, maintaining energy-release efficiency while enhancing the mechanical properties of the propellants presents a significant challenge. Optimizing the interfacial relationships among various propellant components can potentially improve both the mechanical performance and energy-release efficiency of these propellants. This study developed a straightforward method using tannic acid (TA) and Fe3+ ions to create an interfacial layer on ammonium perchlorate (AP) particles (referred to as AP@TA-Fe) for achieving enhanced AP energy-release efficiency and mechanical properties of the propellant. AP@TA-Fe composites with different TA-Fe mass ratios (2, 4, and 6 wt%) were prepared, tested, and characterized. The experimental results demonstrated the interface-engineered AP@TA-Fe displayed enhanced hydrophobicity and rapid energy release, and these effects intensified with increasing interfacial layer thickness. The TA-Fe interfacial layer significantly enhanced the tensile strength and elongation of the propellant under various temperature conditions. As the thickness of the TA-Fe layer increased, the damage mechanism of the modified propellant shifted from the dewetting of the AP particles to the tearing of the adhesive matrix. Consequently, the AP@TA-Fe composites are expected to serve as superior substitutes for traditional AP in propellant applications. [ABSTRACT FROM AUTHOR]

Background and Objectives: Wood has some limitations in properties and applications due to its natural nature, which need to be modified. Wood modification is usually done with different aims and methods. One of the wood modification methods is thermal treatments in order to improvement of dimensional stability and biological resistance. But, it is surely affected on physical and mechanical properties of wood. Wood thermal modification in presence of oxygen causes the oxidation of its chemical structure which leads to detrimental effects on physical and mechanical properties. Therefore, elimination of oxygen in thermal modification can reduce its destructive effects. In current study, the effect of thermo-oil process on the function of white rot fungus has been investigated. Moreover, the effect of this process on engineering properties of birch and pine wood species was evaluated. Methodology: In this study, two wood species of birch (Betula sp.) and pine (Pinus sp.) wood were cut into the desired lumbers. Heat treatment of the prepared lumbers was carried out in a cylinder which is equipped with pressure and vacuum system. Also, industrial recycled oil was used for heat treatment of the lumbers. The temperature and time of treatment were selected as 195 °C and 5 hours, respectively. At the end of the process, the used oil was drained into the oil storage tank and the lumbers were removed from the cylinder after applying vacuum. In order to investigation of biological resistance as well as physical and mechanical properties (water absorption and swelling, density, mass loss, bending strength, compression strength parallel to the grain and impact strength) test specimens were prepared from the treated and control lumbers based on the standard. The SPSS software was used for statistical analysis. The results were statistically analyzed based on a One-Way ANOVA method. Results: Results revealed that thermo-oil treatment can reduce the functionality of white rot fungus and also its efficiency on physical and mechanical properties of both wood species. Moreover, the results showed that this process improved the physical properties and reduced the mechanical properties, except compression strength parallel to the grain. Conclusion: Thermo-oil treatment at high temperature causes structural changes of wood and affects its physical and mechanical properties. Also, the structural changes caused by heat treatment can be an effective and inhibiting factor to functionality of white rot fungus on physical and mechanical properties of wood. [ABSTRACT FROM AUTHOR]

Gerotors are a family of mechanical pumps used for cooling, lubrication and fuel transfer in aerospace, medicine, etc. Modern industry demands to shorten the development time of products. This means further integration between the different design stages. As in any hydraulic machinery, an important bottleneck in the design process is the simulation time to validate designs. This is due mainly to the fact that Computational Fluid Dynamics (CFD) remains the go-to tool to perform simulations of hydraulic phenomena. One way to reduce this bottleneck is to adopt approximate yet fast simulation routines to refine the design before entering a precise simulation stage. This manuscript presents an interactive design tool that estimates the efficiency response of gerotor pumps using fast simulation routines. The presented tool intends to shorten and accelerate the design cycles of Gerotor pumps by providing the engineer with an estimation of the effect of geometry changes in the pump's efficiencies in real time. The software tool integrates 2D and 3D design capabilities with real-time simulation response. The resulting efficiency estimations differ from the CFD models in maximum 8% in the case of volumetric efficiency. For mechanical efficiency the error ranges between around 20% and 45%, but the pump's internal forces is estimated within a 1% accuracy. Future work focuses on refining the accuracy of the efficiency estimations and further integration of the design tool with physical data. [ABSTRACT FROM AUTHOR]

Lattice structures are widely used in load-bearing and energy-absorption applications for their lightweight, high specific stiffness, high specific strength and excellent energy-absorption. A novel hybrid lattice cell that combining octet cell and body-centered cube cell was proposed, and quasi-static compression experiments and finite element simulations were performed to investigate their energy-absorption characteristic and deformation mechanisms. The effects of the relative density, configuration of cell and component ratio sub-cell on the compression responses were also explored. The results showed that hybrid lattice improves compression modulus and yield strength by 10% and 16% maximally, respectively, and the energy-absorption of enhancement is 20% higher than the conventional lattices. In addition, the hybrid lattice can significantly alleviate the stress softening. By increasing the volume ratio of body centered cubic in the hybrid lattice structures, the energy-absorption can be improved. Under dynamic loading, the proposed hybrid lattice structures displayed outstanding normalized yield strength, which is superior to majority of porous structures. Inspired by the precipitation hardening mechanisms used in metallurgy to design high-performance alloys, two dual-phase lattices are developed. The quasi-static compression of dual-phase lattices shows three stages plateau stress and has a higher third stage than that of traditional dual-phase lattices. These findings provided design strategy for lightweight structure. [ABSTRACT FROM AUTHOR]

The mechanical durability and efficiency of all‐inorganic flexible perovskite solar cells (f‐PSCs) still require enhancement for practical applications. In this study, a creative debridement strategy to improve the mechanical durability and photovoltaic performance of all‐inorganic f‐PSCs by pre‐bending the flexible perovskite film and then depositing the passivation agent 2‐mercaptopyridine is proposed. The pre‐bending process induced the generation of microcracks in the perovskite film surface, and 2‐mercaptopyridine can more effectively penetrate the interior of the film through the microcracks, thereby further passivating deep surface defects. These microcracks and defects can be perfectly repaired by 2‐mercaptopyridine. Bidentate coordination sites of S and N in 2‐mercaptopyridine show stronger binding energy with surface defects. The debridement strategy effectively enhanced the crystallization of the film surface and markedly inhibited crack propagation during the film's bending process. The optimized device achieves a champion power conversion efficiency (PCE) of 14.74%. The pre‐bent and passivated all‐inorganic f‐PSC shows 104% of its initial PCE after 15 000 bending cycles at a curvature radius of 3 mm. Remarkably, even after undergoing 70 000 bending cycles at a curvature radius of 5 mm, pre‐bent, and passivated f‐PSC can retain over 93% of its initial PCE, exhibiting excellent mechanical durability. [ABSTRACT FROM AUTHOR]

One of the main challenges in super high-density olive is maintaining hedgerow structure suitable for mechanical harvesting. Deficit irrigation strategies (DI) can contribute to this maintenance. In this study, three DI treatments at 50% of the Control (DI-1: budbreak to pre-bloom, DI-2: fruit set to pit hardening, and DI-3: pit hardening to harvest) were applied to 6-year-old Arbequina hedgerows in a semi-arid environment of Argentina over three consecutive seasons. The mean applied water reduction was 12% for DI-1 and 16% for DI-2 and DI-3, compared to Control (100% of ETc throughout the cycle). DI-3 achieved the narrowest hedgerows at harvest, where canopy height was responsive to irrigation and canopy width was affected by fruit load but not by the irrigation regime. DI-1 demonstrated similar fruit and oil yields to Control throughout the experiment, while DI-2 only had comparable yields to Control in Off-season. DI-3 had the lowest oil yields, averaging – 27% in Off and On-seasons. The fruit number was similar among treatments in all seasons, indicating that differences in final yield were related to fruit size and oil concentration. Further studies are needed to determine the optimal duration and intensity of the water deficit for DI-3. [ABSTRACT FROM AUTHOR]

This paper investigates the feasibility of the Biofuel and diesel used in a proportionate mixture as a Biodiesel as a replacement for Diesel fuel. Biodiesel has gained significant attention in the power world as an alternative to biodiesel blends prepared in this study is 50% Neem and 50% Pongamia pinnate. During the study, the blends used for testing were B5%, B10%, B15% and B20% with a varying load condition of 3kg to 20kg in a single-cylinder diesel engine at rpm of 1600 with a load of 19.01kg. A pyrolysis method is used for making Biodiesel. The viscosity values of the Biodiesel blend lie in the range of 3.89 to 8.756 Nm/s2 1. The performance of biodiesel has been analysed in terms of break power, indicated power, break and indicated thermal efficiency, mechanical efficiency, torque, specific fuel consumption, and volumetric efficiency. The parametric value of the all curve shows the increasing behaviour from lower to higher value. Volumetric efficiency shows only decreasing behaviour concerning load. The result shows the B5% blend is better in break power by 13.43% than a diesel at a load of 19.01kg. And specific fuel consumption. The torque generated is more efficient in B20% blends. Break thermal efficiency is proportional to the load of the engine. Indicated Thermal efficiency is much higher than diesel of B5% Biodiesel. The maintenance of a fuel pump is required regularly due to more viscosity problems. [ABSTRACT FROM AUTHOR]

This paper introduces a test system for microwave-assisted dual-mode mechanical cutting of hard rock under true triaxial compression. The test system was developed by Northeastern University, China, to simulate the cutting and breaking of hard rock by a tunnel boring machine (TBM). The test system is mainly composed of a dual-mode mechanical cutting subsystem, a true triaxial loading subsystem and a high-power microwave presplitting subsystem. The system performs dual-mode cutting under true triaxial stress, applies a single sensor to monitor the three-dimensional force of the cutter head, and integrates the reduction in the vibration and resistance to torsion during the cutting process. Mechanical cutting tests of basalt under different amounts of microwave irradiation and true triaxial stress conditions were conducted in Chifeng, Inner Mongolia, China. The results showed that microwave radiation presplitting effectively improved the efficiency of mechanical rock breaking. However, after 180 s of microwave irradiation, true triaxial high stress inhibited the mechanical breaking of basalt in terms of the overall excavation depth. During the tests, each system performed stably. The test results verified the reliability of the test system. Highlights: A true triaxial stress microwave-assisted mechanical dual-mode cutting test system is independently developed. The proposed system simulates rock breaking by a microwave-assisted roadheader under different ground stress conditions. The cutting test system innovates in three main facets: it carries out a dual-mode cutting test system in rock breaking; it realizes a unified monitoring output of a single sensor for the three-dimensional force; and it integrates the seismic resistance and torsion resistance to create a smooth system body. As the cutting test is conducted, the effective influence range of microwave radiation on rock is verified, and the degree of influence of true triaxial high stress on microwave-assisted mechanical cutting is revealed, providing guidance for deep microwave-assisted rock breaking of roadheaders. The necessity and feasibility of the system development is thus verified. [ABSTRACT FROM AUTHOR]

In automatic transmissions, hydraulic oil in the oil sump is strongly agitated by gears during operation; thus, the oil is mixed with great amounts of air. Air-mixed oil is sucked and discharged by a hydraulic pump to shift the gears. Although air bubbles mixed in the oil may affect the behavior of the rotors, driving torque, and discharge flow rate, they have hardly been measured. In this study, we measure them using a balanced vane pump and a gerotor pump used for automatic transmissions under varying air bubble contents and operating conditions. The experimental results revealed that the inclusion of air bubbles in the oil somewhat influenced the rotor behavior of both test pumps but it did not seem to increase the contact between the rotor and the surrounding stationary parts. Furthermore, as the bubble content increased, friction torque decreased to some degree, while discharge flow rate decreased to a great degree. This work proposed a new friction torque model, in which bubble content is included as a parameter, and the proposed model demonstrated relatively good agreement with the measured friction torque characteristics. The results also revealed that the rotor behavior and friction torque characteristic were mainly affected by bubble content and less so by bubble size. [ABSTRACT FROM AUTHOR]

Objective: This study investigated whether exposure to suboptimal gestational factors (SGFs) alters mechanical efficiency (ME) and substrate oxidation during rest and exercise in children as a mechanism contributing to obesity. Methods: Data from the Quebec Adiposity and Lifestyle Investigation in Youth cohort were used. Children aged 8 to 10 years performed an incremental maximal cycling test with indirect calorimetry. Their ME was measured during submaximal and maximal effort. The substrate oxidation during rest and submaximal effort was also computed. ME and substrate oxidation results between children exposed to each SGF during pregnancy (gestational diabetes mellitus: n = 68; hypertensive disorders: n = 49; maternal smoking: n = 77) and nonexposed children (n = 370) were compared. Results: No difference was observed for ME during submaximal (F[3,540] = 0.46, p = 0.713) and maximal effort (F[3,545] = 0.86, p = 0.463) between exposed and nonexposed children. The percentage contributions of lipids and carbohydrates did not differ during rest (F[3,545] =1.68, p = 0.169) or submaximal exercise (F[3,544] = 0.31, p = 0.534) between exposed and nonexposed children. Conclusions: Children exposed to investigated SGFs display a similar physiological response regarding ME and substrate oxidation during rest and exercise compared to nonexposed children. Future studies should confirm these novel results and continue investigating other research avenues to explain the higher risk of obesity in this population. [ABSTRACT FROM AUTHOR]

A high voltage circuit breaker (HVCB) plays a crucial role in current smart power system. However, the current research on HVCB mainly focuses on the convenience and efficiency of mechanical structures, ignoring the aspect of their fault diagnosis. It is very important to ensure the circuit breaker conducts in a normal state. According to real statistics when HVCB works, most defects and faults in high voltage circuit breakers is caused by mechanical faults such as contact fault, mechanism seizure, bolt loosening, spring fatigue and so on. In this study, vibration sensors were placed at four different locations in the HVCB system to detect four common mechanical faults using vibration signal. In our approach, a convolutional attention network (CANet) was introduced to extract features and determine which mechanical faults occur within a fixed period of time. The results indicate that the mechanical fault diagnosis accuracy rate is up to 94.2%, surpassing traditional methods that rely solely on vibration signals from a single location. [ABSTRACT FROM AUTHOR]

Introduction: Domestic production of pepper (Capsicum spp.) is shrinking while demand within the US is growing. Lack of availability and cost of labor often present an obstacle for domestic producers both practically and economically. As a result, switching to harvesting peppers mechanically is anticipated as a key strategy to help domestic producers compete in the international market. Mechanical harvest efficiency can be improved through breeding. One important trait that mechanical harvest compatible material should have is an easy destemming trait: low force separation of the pedicel and calyx fromthe fruit. Methods: To detect the genetic sources underlying a novel easy destemming trait for the purpose of future breeding efforts in New Mexico pod-type green chile, we performed QTL analysis on three F2:F3 populations, coming from three New Mexico pod-type varieties: 'NuMex Odyssey,' 'NuMex Iliad,' and 'NuMex Joe E. Parker,' each crossed with a parent with an easy destemming trait: MUC14. Genotyping was done through genotyping by sequencing (GBS) and phenotyping was done for destemming and fruit trait measurements. Correlations between measurements were found through the R package hmisc and QTL analysis was done through R/qtl. Results: A strong relationship was seen between destemming and aspects of fruit morphology, particularly, destemming force and fruit width (Pearson's correlation coefficient r=0.75). Major QTLs for destemming and fruit size were discovered. Of these, the largest destemming force QTLs for all populations (PVE=34.5-69.9%) were on chromosome 10, and in two populations QTLs for destemming force were found on chromosome 3 (Percent Variance Explained (PVE)=10.7-18.8%). Fruit size-related QTLs in all populations colocalized in these same areas on chromosomes 3 and 10. Discussion: This suggests that fruit shape may be genetically linked to destemming, and breeders interested in selecting for easy destemming pepper will also have to pay attention to fruit size and shape. [ABSTRACT FROM AUTHOR]

AbstractBackgroundAimMaterials and MethodsResultsConclusion\nIMPLICATIONS FOR REHABILITATIONWhen selecting a manual wheelchair frame, the choice between rigid and folding frames carries significant implications. Traditional folding frames are expected to have more rolling resistance and power dissipation caused by frame deformation, while they are more convenient for transportation, such as in a car. A new hybrid frame, designed to be more rigid, aims to minimize power dissipation while still retaining foldability.This study aimed to assess rolling resistance, power output, propulsion technique and physiological demands of handrim wheelchair propulsion across three different frames: a rigid frame, a hybrid frame and a conventional folding frame.Forty-eight able-bodied participants performed coast-down tests using inertial measurement units to determine rolling resistance. Subsequently, four-minute submaximal exercise block under steady-state conditions at 1.11 m/s were performed on a wheelchair ergometer (n = 24) or treadmill (n = 24) to determine power output, propulsion technique and physiological demands.Repeated measures ANOVA revealed that the hybrid frame exhibited the lowest rolling resistance (7.0 ± 1.5N, p ≤ 0.001) and required less power output (8.3 ± 1.0W, p ≤ 0.001) at a given speed, compared to both the folding (9.3 ± 2.2N, 10.8 ± 1.4W) and rigid frame (8.0 ± 1.9N, 9.4 ± 1.6W). Subsequently, this resulted in significantly lower applied forces and push frequency for the hybrid frame. The folding frame had the highest energy expenditure (hybrid: 223 ± 44 W, rigid: 234 ± 51 W, folding: 240 ± 46 W, p ≤ 0.001).The hybrid frame demonstrated to be a biomechanically and physiologically beneficial solution compared to the folding frame, exhibiting lower rolling resistance, reduced power output, and consequently minimizing force application and push frequency, all while retaining its folding mechanism.A hybrid frame, developed as an intermediary solution between a folding and rigid frame, presents reduced biomechanical and physiological demands compared to a folding frame. This is attributed to its decreased need for propulsive forces and energy expenditure, resulting from lower rolling resistanceDespite the hybrid frame offering lower rolling resistance and thus requiring less propulsive force as the rigid frame, it experiences internal power losses due to movement between its interconnected pieces. Consequently, the net mechanical efficiency of the hybrid frame is inferior to that of the rigid frame, resulting in a similar energy expenditure between the hybrid and rigid frames.The hybrid frame emerges as a potentially more advantageous option than a conventional folding frame, as it diminishes biomechanical and physiological strain while retaining a folding mechanism, to ensure easy transportation.A hybrid frame, developed as an intermediary solution between a folding and rigid frame, presents reduced biomechanical and physiological demands compared to a folding frame. This is attributed to its decreased need for propulsive forces and energy expenditure, resulting from lower rolling resistanceDespite the hybrid frame offering lower rolling resistance and thus requiring less propulsive force as the rigid frame, it experiences internal power losses due to movement between its interconnected pieces. Consequently, the net mechanical efficiency of the hybrid frame is inferior to that of the rigid frame, resulting in a similar energy expenditure between the hybrid and rigid frames.The hybrid frame emerges as a potentially more advantageous option than a conventional folding frame, as it diminishes biomechanical and physiological strain while retaining a folding mechanism, to ensure easy transportation. [ABSTRACT FROM AUTHOR]

Microwave treatment has become a promising method to improve the efficiency of mechanical excavators in hard rocks. This paper conducted microwave irradiation tests on three water-bearing sandstones and analyzed the heating and water-escaping process by real-time temperature and mass measurement. Meanwhile, nuclear magnetic resonance tests were performed to investigate the water transport behavior inside the samples under microwave irradiation. The results show that the thermal behaviors are jointly governed by the water content, permeability and microwave power used. As the sample temperature increase, the contained water would firstly transport from the drying front to the surface driven by the temperature gradient. Subsequently, water began to escape from the sample with a rate determined by the permeability of the sandstone. At this stage, energy dissipation brought by water escaping would slow down the initial heating rate. Hence, the thermal cracking of the sandstones under microwave irradiation can hardly be enhanced by the existence of pore water in spite of its superior dielectric properties. Nevertheless, the vapor pressure could be large enough to burst the sample when water was heated to a high temperature. Highlights: Obtained the real-time temperature and mass change under microwave irradiation Investigated the water transport behavior in sandstones using nuclear magnetic resonance techniques Discussed the role water plays in microwave heating, fracturing and bursting of sandstones [ABSTRACT FROM AUTHOR]

This article explores the intersubjective relationships between clients and workers on two digital domestic work platforms in Bogotá, Colombia. Drawing on feminist social studies of science and technology, it investigates the control, auditing, and subordination mechanisms affecting workers, with clients playing a key role in setting performance conditions. While much of the literature on digital labor focuses on technological intermediation and algorithmic management--used to track, monitor, and rate domestic workers--this article looks at the relationships with clients and how these shape the work process and technologies involved. Based on over thirty in-depth interviews with workers and clients, the study examines three areas: (i) clients' expectations of mechanical efficiency; (ii) the use of rating systems; and (iii) domestic work as emotional labor. The article concludes by reflecting on the dual subordination experienced by workers due to digital service intermediaries and emphasizes the need for fair technologies that consider workers' experiences and perspectives. [ABSTRACT FROM AUTHOR]

The efficiency of mechanical crushing is a key metric for evaluating machinery performance. However, traditional contact-based methods for measuring this efficiency are unable to provide real-time data monitoring and can potentially disrupt the production process. In this paper, we introduce a non-contact measurement technique for mechanical crushing efficiency based on deep learning algorithms. This technique utilizes close-range imaging equipment to capture images of crushed particles and employs deeply trained algorithmic programs rooted in symmetrical logical structures to extract statistical data on particle size. Additionally, we establish a relationship between particle size and crushing energy through experimental analysis, enabling the calculation of crushing efficiency data. Taking cement crushing equipment as an example, we apply this non-contact measurement technique to inspect cement particles of different sizes. Using deep learning algorithms, we automatically categorize and summarize the particle size ranges of cement particles. The results demonstrate that the crushing efficiencies of ore crushing particles, raw material crushing particles, and cement crushing particles can respectively reach 80.7%, 70.15%, and 80.27%, which exhibit a high degree of consistency with the rated value of the samples. The method proposed in this paper holds significant importance for energy efficiency monitoring in industries that require mechanical crushing. [ABSTRACT FROM AUTHOR]

CF‐PDA‐M hybrid fillers are prepared by three metal cations (M) assisting polydopamine (PDA) through Fe3+, Ni2+, and Al3+. The metal cations promote the polymerization of PDA on the fiber surface, shorten the modification time of the fibers, and ensure that the short‐cut carbon fibers (CF) do not agglomerate during water bath stirring while keeping the structure of the CF undamaged, which is a green and efficient method. After PDA modification, the roughness and surface activity of the fiber surface increase. Finally, CF‐PDA‐M is used as a filler and added to neoprene latex and natural latex, which are prepared into composites by wet blending, and the CF are characterized by different techniques. The results show that the hydroxyl and amino groups on the surface of CF‐PDA‐M increase the cross‐linking density of the composites, establish a good stress cross‐linking network, shorten the vulcanization time, effectively prevent the agglomeration phenomenon of the CF in the rubber, and improve the dispersion of the CF in the composite. After modification, the tensile strength and 300% constant tensile strength of CF‐PDA‐M increase by more than 10% and 30%, respectively, over CF composites, and the rolling resistance is reduced. This study provides a new and effective strategy for CF surface functionalization, which improves the processing efficiency and mechanical properties of rubber products and has a broad application prospect in the rubber industry. [ABSTRACT FROM AUTHOR]

Radial piston motors are executive components in hydraulic systems, tasked with providing appropriate torque and speed according to load requirements in practical applications. The purpose of this study is to predict the output torque of radial piston hydraulic motors and confirm their suitable operating conditions. Efficiency determination experiments were conducted on physical models, yielding thirty sets of performance data. Torque (output torque) and mechanical efficiency from the experimental data were selected as prediction targets and fitted using two methods: multiple linear regression and neural networks. A dynamic simulation model was built using Adams2020 software to obtain theoretical torque values, enabling the verification of the alignment between the predicted values and simulation results. The results indicate that the error between the theoretical torque of the dynamic model and the physical experiments is 1.9%, with the error of the neural network predictions being within 2%. The dynamic simulation model can yield highly accurate theoretical torque values, providing a reference for the external load of hydraulic motors; additionally, neural networks offer accurate predictions of output torque, thus reducing experimental testing costs. [ABSTRACT FROM AUTHOR]

Drilling is a complex destructive action that induces vibrations due to the rock-bit interaction, which affects the overall drilling efficiency and wellbore quality. This study aims to enhance drilling efficiency by deploying artificial neural networks (ANNs) to integrate in-cutter force sensing and vibration data. Data is collected from experiments conducted with sharp cutters on rock samples of varying mechanical properties, measuring variables such as weight on bit, torque, rotational speed, in-cutter force, and vibration measurements. A scoring system is used to evaluate the drilling efficiency by coupling the mechanical specific energy and vibration modes. An ANN is trained with these variables to predict the rate of penetration and rock strength, which are also measured in the experiments to be used as ground truth. The reliability of the framework is demonstrated by testing the validity of the ANN model on samples with various mechanical properties. It introduces a reliable and swift method for determining optimal drilling parameters, supported by a sensitivity analysis to fine-tune the ANN and assess the influence of each parameter on performance. This study demonstrates that ANN could be successfully implemented to predict the rate of penetration and rock strength on a laboratory-scaled drilling rig. The results show that the ANN model accurately predicts training and testing datasets for scoring while drilling multiple layers with a correlation coefficient of 0.966. Integration of in-cutter sensing technology, vibration data, and ANN can be of significant interest and be used on field applications to provide a reliable and rapid decision about drilling efficiency. [ABSTRACT FROM AUTHOR]

One-dimensional structured fillers play a crucial role in promoting the rapid and spontaneous healing of defects induced by damage in self-healing coatings. This innovative type of self-healing coating prevents the substrate material from corroding, thereby significantly extending its service life. The modification of self-healing coatings with one-dimensional structured fillers relies on functional additives to efficiently heal coating damage, distinguishing it from traditional approaches involving microcapsules and nanoencapsulated particles. The incorporation of advanced fillers not only enhances the local reconstruction efficiency and mechanical properties of the coating but also enables the coating to heal the damage repeatedly. In this paper, the latest research progress on one-dimensional structured fillers for self-healing coatings is reviewed from three aspects: types of functional fillers with one-dimensional structures, packaging processes for repairing agents in fillers, and self-healing mechanisms of the composite coating. Furthermore, future work has been proposed to address present problems in the research of one-dimensional structured filler-modified self-healing coatings. One-dimensional structured fillers and their applications in self-healing composite coatings. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) are recognized for energy conversion efficiency and applications including electronics and energy storage devices. This study introduces a groundbreaking development in TENG by incorporating negative Poisson's ratio metamaterials to fabricate auxetic‐assisted triboelectric nanogenerators (Auxetic‐TENG), subversively overcoming the low power density of traditional materials. Subtly, an integrated layer‐by‐layer‐assembly and core–shell accumulation strategy is employed to create a synclastic polytetrafluoroethylene negative friction shell‐skeleton, into which positive Poisson's ratio nature collagen aggregate (CA) foam is inwardly embedded as the positive friction core‐material. Surprisingly, the on‐demand introduction of metamaterials in synergy with CA significantly increases the contact area and mechanical energy absorption of the Auxetic‐TENG under pressure. This enhancement in the conversion efficiency of mechanical to electricity capitalizes on the contraction origins of negative Poisson's ratio metamaterials, integrated with the expansion characteristics of the positive Poisson's ratio materials within the structure, facilitating the synergistic compression of the positive and negative friction stratum. Consequently, Auxetic‐TENG achieves an open‐circuit voltage of 85 V, an overturning four times compared to conventional contact–separation TENG, and a power density of 4.2 W m−2. Application experiments demonstrate the superior performance of auxetic‐TENG under various compression ratios and stress conditions, highlighting its potential for real‐time monitoring in healthcare applications. [ABSTRACT FROM AUTHOR]

The field of production engineering is constantly attempting to be distinguished for promoting sustainability, energy efficiency, cost-effectiveness, and prudent material consumption. In this study, three control parameters (3D printing settings), namely nozzle temperature, travel speed, and layer height (LH) are being investigated on polyamide 6/carbon fiber (15 wt%) tensile specimens. The aim is the optimum combination of energy efficiency and mechanical performance of the specimens. For the analysis of the results, the Box-Behnken design-of-experiment was applied along with the analysis of variance. The statistical analysis conducted based on the experimental results, indicated the importance of the LH control setting, as to affecting the mechanical strength. In particular, the best tensile strength value (σB = 83.52 MPa) came from the 0.1 mm LH. The same LH, whereas caused the highest energy consumption in 3D printing (EPC = 0.252 MJ) and printing time (PT = 2272 s). The lowest energy consumption (EPC = 0.036 MJ) and printing time (PT = 330 s) were found at 0.3 mm LH. Scanning electron microscopy was employed as a part of the manufactured specimens' 3D printing quality evaluation, while Thermogravimetric analysis was also conducted. The modeling approach led to the formation of equations for the prediction of critical metrics related to energy consumption and the mechanical performance of composite parts built with the MEX 3D printing method. These equations proved their reliability through a confirmation run, which showed that they can safely be applied, within specific boundaries, in real-life applications. [ABSTRACT FROM AUTHOR]

The contradiction between the migration rate of molecular chains and mechanical strength has always been a key factor affecting the practical application of self‐healing anticorrosion coatings. In this paper, a series of supramolecular self‐healing elastomers (SPU‐MP) were prepared by the reaction of diphenylmethane diisocyanate and polyether amine. The results shown that the proportion of polyetheramine D230 (D230) in molecular segments affects the hydrogen bond density between molecular chains, thereby affecting the self‐healing efficiency and mechanical strength of SPU‐MP. When the ratio of D230 and polyetheramine D400 (D400) is 2:8, the tensile fracture strength of SPU‐MP8 is 5.08 MPa, and the self‐healing efficiency reaches 82.1% after 10 h of repair at room temperature. Further increasing the ratio of D230 increases the relaxation time of the molecular chain due to the increase in hydrogen bond density, resulting in a decrease in the self‐healing efficiency of SPU‐MP. The results of electrochemical experiments and neutral salt spray experiments indicate that the anticorrosion coating prepared by SPU‐MP8 exhibits good self‐healing performance. After immersing in 3.5 wt.% NaCl solution for 35 days, the low‐frequency impedance modulus of the intact coating and the scratch coating were both higher than 107 Ω cm2, still shown good anticorrosion ability. [ABSTRACT FROM AUTHOR]

In order to achieve efficient and durable oil-water emulsion separation, the membranes possessing high separation efficiency and mechanical strength attract extensive attention and are in great demand. In present study, a kind of polytetrafluoroethylene (PTFE)-based bilayer membrane was fabricated by electrospinning fibrous PTFE (fPTFE) on an expanded PTFE (ePTFE) substrate. The morphological observation revealed that the fibrous structure of the fPTFE layer could be tailored by controlling the formulation of spinning solution. The addition of appropriate polyoxyethylene (PEO) would make the fibers in the fPTFE layer finer and more uniform. As a result, the compounded membrane exhibited a small pore size of approximately 1.25 µm and a substantial porosity nearing 80%. This led to super-hydrophobicity, characterized by a high water contact angle (WCA) of 149.8°, and facilitated rapid oil permeation. The water-in-oil emulsion separation experiment further confirmed that the compounded membrane not only had a high separation efficiency closing 100%, but such an outstanding separation capacity could be largely retained, either through multiple cycles of use or through strong acid (pH=1), strong alkali (pH=12), or high-temperature (100 °C) treatment. Additionally, the mechanical behavior of the bilayer membrane was basically contributed by that of each layer in terms of their volume ratio. More significantly, the poor creep resistance of fPTFE layer was suppressed by compounding with ePTFE substrate. Hence, this study has laid the groundwork for a novel approach to create PTFE-based compounded membranes with exceptional overall characteristics, showing promise for applications in the realm of emulsion separation. [ABSTRACT FROM AUTHOR]

In this paper, dynamic modeling and simulation of a new hydraulic fluid flow control strategy which is inlet throttled pump is presented with the goal of studying the system efficiency and feasibility. In this system, a valve is used at the pump inlet to restrict the flow which reduces the power losses that exist with traditional valve control systems in which the valve is placed at the pump discharge. In addition, the proposed system uses a fixed displacement pump which has lower cost and simpler dynamics compared to displacement controlled pumps. The mathematical models created in this work include models for the volumetric and mechanical efficiencies of the system. Experiments have been performed to validate the mathematical models proposed in this work. The effects of the inlet pressure, supply pressure, pump angular speed, and valve opening area on the volumetric and mechanical efficiencies of the pump were investigated. The results demonstrated that the system has great volumetric efficiency which increases with the increase of the pump speed and decreases with the increase in the discharge pressure. The inlet pressure and the valve opening area were shown to have no significant impact on the volumetric efficiency. The mechanical efficiency of the system was shown to be proportional to the valve opening area, inlet and supply pressures and inversely proportional to the angular speed of the pump. It can be seen that excellent agreement between the theoretical and experimental results was achieved. The results of the present work reveals that the proposed system can be used as an excellent alternative of the available hydraulic fluid flow control strategies in terms of feasibility, efficiency, cost, and simplicity. [ABSTRACT FROM AUTHOR]

This study investigates the performance of two types of multi-encapsulated electrode (MEE) plasma actuators, compared to typical dielectric barrier discharge (DBD) plasma actuators, in quiescent air. The objective is to determine whether the multiple encapsulated structure can enhance the performance of the plasma actuator. In the present paper, flow characteristics are investigated by using particle image velocimetry (PIV) and Schlieren visualisation. In addition, the distribution of body force over the gas volume based on the Navier–Stokes equations is calculated from velocity measurements. The obtained results demonstrate that the starting vortex behavior is influenced by electrode arrangement. Specifically, it can be observed that when the first encapsulated electrode is positioned closer to the exposed electrode, then a significantly higher induced velocity can be obtained compared to the baseline condition. In fact, the induced velocity can be increased by up to 1.5 times under this optimize configuration. These results highlight the importance of electrode arrangement in the plasma actuator design. Based on body force estimation, MEE plasma actuators exhibit a significantly higher momentum transfer, particularly in the wall normal direction. The investigation on the mechanical efficiency also reveals that the optimized configuration proposed in the present study can significantly enhance the efficiency. In fact, a four-fold increase in maximum efficiency compared to the typical configuration is observed. These results suggest that the proposed configuration could be considered a promising solution for improving the mechanical efficiency of plasma actuators. [ABSTRACT FROM AUTHOR]

It is increasingly important to monitor sliding interfaces within machines, since this is where both energy is lost, and failures occur. Acoustic emission (AE) techniques offer a way to monitor contacts remotely without requiring transparent or electrically conductive materials. However, acoustic data from sliding contacts is notoriously complex and difficult to interpret. Herein, we simultaneously measure coefficient of friction (with a conventional force transducer) and acoustic emission (with a piezoelectric sensor and high acquisition rate digitizer) produced by a steel–steel rubbing contact. Acquired data is then used to train machine learning (ML) algorithms (e.g., Gaussian process regression (GPR) and support vector machine (SVM)) to correlated acoustic emission with friction. ML training requires the dense AE data to first be reduced in size and a range of processing techniques are assessed for this (e.g., down-sampling, averaging, fast Fourier transforms (FFTs), histograms). Next, fresh, unseen AE data is given to the trained model and the resulting friction predictions are compared with the directly measured friction. There is excellent agreement between the measured and predicted friction when the GPR model is used on AE histogram data, with root mean square (RMS) errors as low as 0.03 and Pearson correlation coefficients reaching 0.8. Moreover, predictions remain accurate despite changes in test conditions such as normal load, reciprocating frequency, and stroke length. This paves the way for remote, acoustic measurements of friction in inaccessible locations within machinery to increase mechanical efficiency and avoid costly failure/needless maintenance. [ABSTRACT FROM AUTHOR]

This study investigates the performance dynamics of a six-cylinder, inline compression ignition engine, focusing on its response to varying turbocharger compressor pressure ratios (TCPRs). At a constant speed of 1500 RPM, the engine's power output, braking mean effective pressure, and brake torque increase significantly, ranging from 280 kW, 11.7 bar, and 1779.7 N m at a TCPR of 2–1042.6 kW, 43.7 bar, and 6637.8 N m at a TCPR of 10. This demonstrates a direct relationship between TCPR and engine performance metrics. Additionally, mechanical efficiency improves with increasing TCPR, indicating enhanced adaptability and efficiency of the engine. The study analyzes the effects of turbochargers, exhaust and intake characteristics, NOx emissions, combustion dynamics, and compressor settings, providing a comprehensive understanding of the relationship between turbocharging and compression ignition engines. These insights can support future research aimed at optimizing engine performance across various TCPR settings.

Designing new acceptors is critical for intrinsically stretchable organic solar cells (IS‐OSCs) with high efficiency and mechanical robustness. However, nearly all stretchable polymer acceptors exhibit limited efficiency and high‐performance small molecular acceptors are very brittle. In this regard, we select thienylene‐alkane‐thienylene (TAT) as the conjugate‐break linker and synthesize four dimerized acceptors by the regulation of connecting sites and halogen substitutions. It is found that the connecting sites and halogen substitutions considerably impact the overall electronic structures, aggregation behaviors, and charge transport properties. Benefiting from the optimization of the molecular structure, the dimerized acceptor exhibits rational phase separation within the blend films, which significantly facilitates exciton dissociation while effectively suppressing charge recombination processes. Consequently, FDY‐m‐TAT‐based rigid OSCs render the highest power conversion efficiency (PCE) of 18.07 % among reported acceptors containing conjugate‐break linker. Most importantly, FDY‐m‐TAT‐based IS‐OSCs achieve high PCE (14.29 %) and remarkable stretchability (crack‐onset strain [COS]=18.23 %), significantly surpassing Y6‐based counterpart (PCE=12.80 % and COS=8.50 %). To sum up, these findings demonstrate that dimerized acceptors containing conjugate‐break linkers have immense potential in developing highly efficient and mechanically robust OSCs. [ABSTRACT FROM AUTHOR]

Sensations of heat and touch produced by receptors in the skin are of essential importance for perceptions of the physical environment, with a particularly powerful role in interpersonal interactions. Advances in technologies for replicating these sensations in a programmable manner have the potential not only to enhance virtual/augmented reality environments but they also hold promise in medical applications for individuals with amputations or impaired sensory function. Engineering challenges are in achieving interfaces with precise spatial resolution, power-efficient operation, wide dynamic range, and fast temporal responses in both thermal and in physical modulation, with forms that can extend over large regions of the body. This paper introduces a wireless, skin-compatible interface for thermo-haptic modulation designed to address some of these challenges, with the ability to deliver programmable patterns of enhanced vibrational displacement and high-speed thermal stimulation. Experimental and computational investigations quantify the thermal and mechanical efficiency of a vertically stacked design layout in the thermo-haptic stimulators that also supports real-time, closed-loop control mechanisms. The platform is effective in conveying thermal and physical information through the skin, as demonstrated in the control of robotic prosthetics and in interactions with pressure/temperature-sensitive touch displays. [ABSTRACT FROM AUTHOR]

Stretchable organic solar cells (OSCs) with high power conversion efficiency and good mechanical deformation are promising as power sources for wearable electronics. However, synergistic improvement of both photovoltaic efficiency and mechanical ductility is challenging for state‐of‐the‐art polymer donor: non‐fullerene acceptor (NFA)‐based photovoltaic active layers. Here, a high‐performance stretchable OSC with a power conversion efficiency of 16.54% and a crack‐onset strain of 26.38% by synergetic optimization film microstructure of sequentially deposited ternary active layer consisting of a polymer donor poly[2,6‐(4,8‐bis(5‐(2‐ethylhexyl‐3‐fluoro)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b']dithiophene))‐alt‐5,5'‐(5,8‐bis(4‐(2‐butyloctyl)thiophen‐2‐yl)dithieno[3',2':3,4;2'',3'':5,6]benzo[1,2‐c][1,2,5]thiadiazole)] (D18), an NFA 2,2'‐((2Z,2'Z)‐((12,13‐bis(2‐ethylhexyl)‐3,9‐diundecyl‐12,13‐dihydro‐[1,2,5]thiadiazolo[3,4‐e]thieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2‐g]thieno[2',3':4,5]thieno[3,2‐b]indole‐2,10‐diyl)bis(methanylylidene)bis(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalonitrile) (Y6), and an elastomer polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene (SEBS) is reported. Adding a low‐content solvent additive para‐xylene into main solvent carbon disulfide induces high‐density fibers networks with low crystallinity in bottom D18 layer, and this further suppresses the large phase separation between Y6 and SEBS in top layer. Moreover, incorporating a solid additive 1,3‐dibromo‐5‐chlorobenzene with better compatibility with Y6 can promote Y6 dispersions to form smaller ordered domains in SEBS matrix. Finally, the optimal ternary active layer shows significantly higher efficiency and stretchability, resulting in a large efficiency‐stretchability factor of 4.36%, which is among the best values for stretchable OSCs. [ABSTRACT FROM AUTHOR]

Natural fibres, valued for their low density, cost-effectiveness, high strength-to-weight ratio, and efficient energy absorption, are increasingly emerging as alternatives to synthetic materials in green composites. Although they cannot fully replace synthetic counterparts, like carbon, in structural applications due to their inferior mechanical performance, combining them through hybridization presents a potential solution. This approach promotes a balance between environmental benefits and mechanical efficiency. Recently, the transportation sector has shifted its focus towards delivering lightweight and crashworthy composite structures to improve vehicle performance, address safety concerns, and minimise environmental impact through the use of eco-friendly materials. The crashworthiness of energy absorbers, typically thin-walled structures, is influenced by several factors, including their material and geometric design. This paper presents a comprehensive overview of recent studies focused on the crashworthiness of fibre-reinforced, thin-walled composites under axial crushing. It explores different aspects, such as their materials, cross-sections, stacking sequences, triggering or filling mechanisms, and the effect of loading rate speed. Emphasis is placed on natural-fibre-based materials, including a comparative analysis of synthetic ones and their hybridization. The primary objective is to review the progress of solutions using green composites as energy absorbers in the automotive industry, considering their lightweight design, crashworthiness, and environmental sustainability. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency of mechanical arms, the time optimal trajectory planning method based on the B‑spline and whale optimization algorithm (WOA) is proposed. The Monte‑Carlo method is used to describe the workspace of the mechanical arms, and then the B‑spline is used to interpolate the given path points. According to the performance of each joint of the manipulator, the angular velocity and angular acceleration constraints are introduced, and the boundary conditions are added. After constructing the target function with optimal time, the WOA with inertia weight is used to optimize the running time of the mechanical arm. Finally, using Matlab for simulation, the results show that the algorithm presented is better than the traditional quintic polynomial method in terms of time optimization, and the angular velocity and angular acceleration curve are continuously smoothed, which verifies the validity and feasibility of the algorithm. [ABSTRACT FROM AUTHOR]