Input Air Research Articles

Reactive Capture of CO2 via Amino Acid

The electrochemical production of carbon monoxide (CO) from carbon dioxide (CO2) has conventionally relied on gas-phase CO2 electrolysis with complex upstream capture and downstream gas separation processes. Reactive capture of CO2 – an integrated approach that combines CO2 capture and electrochemical conversion – uses chemisorbed CO2 directly as the feedstock and thereby avoids CO2 purification and associated costs.To date, reactive capture has relied on hydroxide-based capture solutions (e.g. potassium hydroxide (KOH)) suitable for direct air capture (DAC) processes or amines (e.g. monoethanolamine (MEA)) that have been conventionally used for point source capture. However, in hydroxide-based systems that capture CO2 in the form of carbonate, the CO Faradaic efficiency (FE) is limited to 50% due to the interaction between in-situ regenerated CO2 and local hydroxides that reduce CO2 availability at the cathode. Amine-based reactive capture can overcome this selectivity challenge when CO2 is captured in the form of carbamate and bicarbonate; compared to carbonate, these forms of chemisorbed CO2 require less electron-coupled protons to regenerate in-situ CO2, and thus yield more CO2 at the cathode. However, conventional amines are volatile and have poor oxygen tolerance, rendering them inapplicable to oxygen-rich CO2-lean conditions.Here, we report amino acid salt (AAS)-based reactive capture of CO2 that exceeds the CO energy efficiency (EE) achieved in amine- and hydroxide- based systems. The AAS capture solution, potassium glycinate (K-GLY), contains amino functional groups for efficient CO2 capture while offering advantages including oxygen tolerance, low vapor pressure, and low toxicity. We synthesized a nickel single atom (Ni-N/C) catalyst to improve conversion efficiency, optimized the capture solution composition to reduce the electrolysis overpotential at high current densities, and elevated the operating temperature and pressure to increase availability of dissolved in-situ CO2 at the cathode. We achieve CO production with 64% CO FE and a measured full cell voltage of 2.74 V at 50 mA cm-2, resulting in an CO EE of 31% and an energy intensity of 40 GJ tCO-1. The feasibility of the full reactive capture process was demonstrated with both simulated flue gas and direct air input.

Numerical simulation and experimental study of hydrogen production from chili straw waste gasification using Aspen Plus

Biomass gasification is a promising method for hydrogen production. This study systematically models the gasification of chili straw waste (CSW) using the Aspen Plus simulator, focusing on the effects of gasification agents—steam, air, and oxygen—and sensitivity analyses of key parameters. Results show that under optimal steam gasification conditions, with a temperature of 700 °C and atmospheric pressure, hydrogen concentration reached 59.61%, while the lower heating value (LHV) decreased to 6.65 MJ/m3 due to CO reduction. In air gasification, increasing air input reduced hydrogen and CO concentrations by 18.5% and 26.6%, respectively, while LHV dropped by 52.5%. Oxygen-enriched gasification significantly improved hydrogen and CO concentrations, increasing LHV by 129.4% as the oxygen fraction rose. Sensitivity analysis revealed that optimal hydrogen production in air-steam gasification occurred with a low equivalence ratio of 0.18, moderate temperature around 700 °C, and atmospheric pressure. These findings highlight the critical role of temperature, pressure, and gasifying agents in optimizing hydrogen production, providing a basis for improving the efficiency of biomass gasification systems.

A theoretical model-based methodology to the design of soft structures: A case study of pneumatic mesh actuators

Soft robots offer significant potential in various fields, including healthcare, education, and rescue operations, where actuators are critical components that influence power, precision, and environmental adaptability. However, the nonlinear properties of hyperelastic materials often necessitate reliance on empirical methods and extensive experimentation for actuator design. This study introduces a methodology for designing soft structures, exemplified by pneumatic mesh actuators. Utilizing numerical simulations to investigate deformation patterns and applying the principle of virtual work within a segmented constant curvature framework, a theoretical model was developed to describe the relationships between input air pressure, bending angle of a single airbag, and wall thickness. To validate the model's accuracy and applicability, bending tests were performed on actuators with varying wall thicknesses. A new pneumatic mesh actuator was designed and fabricated using the proposed method, with the experimental results showing a deviation of only 0.27° from the target bending angle under the specified air pressure. This confirms the effectiveness of the proposed design approach. This methodology has potential applications beyond pneumatic mesh actuators, extending to other areas of soft structure design.

Scaling and aspect ratio effects on the frequency-modulated ultrasonic signal generated via fluidic oscillator

Traditional ultrasonic non-destructive testing methods in civil engineering require the use of coupling agents, leading to prolonged and labor-intensivemeasurement procedures along with the risk of surface damage. To alleviate these concerns, air-coupled ultrasonic actuation has been introduced as an effective alternative. However, the power loss due to impedance mismatchs at the interfaces remains an important limitation. To mitigate the power losses at the interfaces while characterizing the specimen thickness, we employ the fluidic oscillator as an ultrasonic source, wherein air acts as both the operating and coupling medium. The fluidic oscillator generates signals through self-sustained oscillations of the exiting air jet under continuous pressurized air supply, and therefore, eliminates the need for intricate design and manufacturing processes. The frequency spectrum characteristics and time-averaged acoustic fields of the fluidic oscillators are shown for the several configurations that were designed by varying the aspect ratio and scaling. Our preliminary investigations highlighted the dependence of the dominant spectral characteristics of a given fluidic oscillator on the mass flow rate of input air. Leveraging this observation, frequency-modulated chirp signals are produced by rapidly varying the flow rate, enhancing the signal-to-noise ratio for a reliable assessment of material characteristics.

Fast, variable stiffness-induced braided coiled artificial muscles

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.

Identification of Yarrowia lipolytica as a platform for designed consortia that incorporate in situ nitrogen fixation to enable ammonia-free bioconversion

Bioconversion processes require nitrogen for growth and production of intracellular enzymes to produce biofuels and bioproducts. Typically, this is supplied as reduced nitrogen in the form of ammonia, which is produced offsite from N2 and H2 via the Haber-Bosch process. While this has revolutionized industries dependent on fixed nitrogen (e.g., modern agriculture), it is highly energy-intensive and its reliance on natural gas combustion results in substantial global CO2 emissions. Here we investigated the feasibility of in situ biological nitrogen fixation from N2 gas as a strategy to reduce greenhouse gas impacts of aerobic bioconversion processes. We developed an efficient and cost-effective method to screen fungal bioconversion hosts for compatibility with the free-living diazotrophic bacterium Azotobacter vinelandii under nitrogen fixing conditions. Our screening revealed that the genus Yarrowia is particularly enriched during co-culture experiments. Follow-up experiments identified four Y. lipolytica strains (NRRL Y-11853, NRRL Y-7208, NRRL Y-7317, and NRRL YB-618) capable of growth in co-culture with A. vinelandii. These strains utilize ammonium secreted during diazotrophic fixation of N2, which is provided as a component of the air input stream during aerobic fermentation. This demonstrates the feasibly of in situ biological nitrogen fixation to support heterotrophic fermentation processes for production of fuels and chemicals.

Computational fluid dynamic simulation of earth air heat exchanger: A thermal performance comparison between series and parallel arrangements

This study uses Ansys Fluent to compare the thermal performance of series and parallel earth air heat exchanger (EAHE) systems for cooling. The model was validated using experimental data from published literature and matched simulation results. The sensitivity study examined how length, diameter, and ground surface coverings affected EAHE performance. The relationship between effectiveness and the Number Transfer Unit (NTU) of EAHE was explored along with the soil thermal regime. The simulation results show that the series EAHE can achieve a lower temperature drop than parallel. With an input air temperature of 32 °C and EAHE lengths varying from 10 m to 50 m (in 10 m increments), the 50 m EAHE produced the lowest outlet air temperatures: 27.2 °C for the series configuration and 28.8 °C for the parallel arrangement. Changing the EAHE diameter (4–6 in) results in a ±0.2 °C outlet air temperature drop for both setups. EAHE performed best under short grass soil cover, yielding 1.4 °C and 0.5 °C lower outlet air temperatures, for series and parallel arrangements than the asphalt cover. The pressure drop increased proportionally with EAHE's length. Simulation results indicate a ±6 times larger pressure loss in the series design compared to the parallel setup. The effectiveness-NTU relationship shows that parallel EAHEs are 15 % more effective than series ones.

Reactive capture of CO2 via amino acid

Reactive capture of carbon dioxide (CO2) offers an electrified pathway to produce renewable carbon monoxide (CO), which can then be upgraded into long-chain hydrocarbons and fuels. Previous reactive capture systems relied on hydroxide- or amine-based capture solutions. However, selectivity for CO remains low (<50%) for hydroxide-based systems and conventional amines are prone to oxygen (O2) degradation. Here, we develop a reactive capture strategy using potassium glycinate (K-GLY), an amino acid salt (AAS) capture solution applicable to O2-rich CO2-lean conditions. By employing a single-atom catalyst, engineering the capture solution, and elevating the operating temperature and pressure, we increase the availability of dissolved in-situ CO2 and achieve CO production with 64% Faradaic efficiency (FE) at 50 mA cm−2. We report a measured CO energy efficiency (EE) of 31% and an energy intensity of 40 GJ tCO−1, exceeding the best hydroxide- and amine-based reactive capture reports. The feasibility of the full reactive capture process is demonstrated with both simulated flue gas and direct air input.

Investigation and optimization heat and humidity environmental control model in construction tunnels: A multifactorial approach incorporating ventilation parameters and hot water quantity

The high rock temperature and hot water influx in the surrounding area of the tunnel construction cause an excessively humid and environment high temperature inside the excavated area of the tunnel, necessitating urgent investigations into the environmental characteristics coupled with these factors and optimizing the control scheme of the construction environment. The on-site data of the tunnel temperature, humidity fields, and external environmental parameters have been collected, along with statistical analysis of the amount of the heat in the resource at the excavation face during the construction period. Subsequently, a three-dimensional numerical model coupling with high rock temperature, hot water, and ventilation was established. Based on the site monitoring data comparison, it was found that the average errors of temperature and humidity field values in the numerical simulation were 4.7 % and 7.1 %, respectively. By introducing the Heat Index (HI), the tunnel environmental characteristics under different conditions were analyzed, showing a linear relationship between the maximum HI at the excavation face and the two following features which are: the temperature-humidity of the input wind, and the hot water quantity. At the same time the air volume exhibited a quadratic relationship. Furthermore, by utilizing multivariate functions to fit the research results, the results show that the maximum HI under various conditions can be predicted. In addition, ultimately establishing an environmental safety assessment model was effective in incorporating multiple factors like input wind temperature, humidity, air volume, and hot water quantity for construction tunnels.

Evaluation of carob tree (Ceratonia siliqua L.) pods, through three different drying techniques, and ultrasonic assisted extraction, for presence of bioactives

The Mediterranean evergreen carob tree (Ceratonia siliqua L.) produces pods, that may be edible and even therapeutic. The purpose of this study was to determine how ethanolic extracts of carob pods from Morocco, prepared with ultrasonic assistance were affected by microwave (525 °C for 2.5 min), hot air (65 °C for 16 h), and spray drying (input and output air temperatures 180 and 90 °C, respectively, feed flow rate 2.5 mL/min and 5 bars, respectively), in terms of their physicochemical composition and biological activity. Colorimetric techniques were utilized to ascertain the phytochemical contents of pod extracts, whereas standardized in vitro methodologies were employed to quantify the antioxidant and antimicrobial activities. Physicochemical analysis showed that microwaved powders of carob pods presented significantly high (p<0.05) values of L* (62.15±0.06) and b* (21.32±0.06), and lower values of a* (4.16±0.03), as compared to spray dried and hot air-dried powders. Significantly high (p<0.05) amounts of ash (3.92±0.05 %), fat (1.48±0.02 %), fiber (7.45±0.12 %) and protein (2.65±0.06 %) were found in microwave dried powders, followed by spray dried and hot air dried. Significant difference in macro and micro minerals among three powders was also observed, as microwave dried powders were found to be significantly high (p<0.05) in Mg, K, Ca, Fe, Zn and Mn, followed by spray dried powders, whereas hot air-dried powders presented lowest values. Similarly, spectrophotometric analysis of phytochemicals revealed that ultrasonic assisted ethanolic extracts of microwave dried powders were found to be highest in total phenolics, flavonoids and carotenoids, with values 69.18±0.15 mg GAE/g, 34.88±0.08 mg QE/g and 24.05±0.15 mg g-1, respectively. In vitro antioxidant and antimicrobial analysis also showed a similar trend as, extracts of microwave dried powders exhibited significantly high (p<0.05) antioxidant and antimicrobial activities, followed by spray dried and hot air-dried. As compared to hot air and spray drying, the microwave drying and ultrasonic assisted extraction using 70 % ethanol as solvent could be employed on carob pods, to obtain powders and extracts, respectively, with minimum degradation of physicochemical characteristics, and maximum retention of nutritional, bioactive and antioxidant contents. Practical applicationsIn recent years, Morocco has become more and more dependent on the use of carob fruit and its powders. Nonetheless, very rare is known about the composition and carob pod quality of those grown in Mediterranean nations. The current study presents a comparison of the effects of three distinct commercial drying methods on the composition and physical characteristics of flour made from carob pods. The study's findings can also be used to evaluate how well information is composed, processed, and preserved for use in future research and commercial applications.

Increasing the Efficacy of an Air Conditioning Unit by Utilizing Phase Change Material With Cylindrical Configuration

ABSTRACTThe goal of the current study is to determine how the SST and the standard turbulence models prediction on PCM with cylindrical configuration affect AC performance and PCM discharging when coupled with an AC unit. For simulation, 308.15 K and 318.15 K, the inflow air temperature has been considered with a fixed 33.6 L/s intake air flow rate. The low outside temperature charges the PCMs during the night. During the daytime, heated ambient air is cooled by the PCM heat exchanger before passing over the unit condenser. The present outcomes show that using the standard model, the cylindrical PCM has the lowest time of complete melting. The temperature contours demonstrate that turbulence occurs, particularly at higher temperatures, in the PCM melting zone within the solid region. This implies that there is increased convection in this area. The maximum improved percentage in COP increases as the rising input air temperature for both turbulence models increases. The average power saving of AC at 308.15 K of an input air temperature for 83.33 min is predicted by both the standard and the SST to be 14.0905 W and 14.1089 W, respectively.

Design of a robotic gripper for casting sorting robots with rigid–flexible coupling structures

AbstractIn order to solve the problem of the insufficient adaptability of the current small- and medium-sized casting sorting robot gripper, we have designed a casting sorting robot bionic gripper with rigid–flexible coupling structures based on the robot topology theory. The second-order Yeoh model was used to statically model the clamping belt in the gripper to derive the relationship between the external input air pressure and the bending angle of the driving layer, and the feasibility of multiangle bending of the driving layer was verified by finite element analysis. The maximum gripping diameter of the gripper is 140 mm, and in order to test the adaptive gripping ability of the gripper, a prototype of the casting sorting robot gripper is prepared, and the pneumatic control system and human–machine interface of the gripper are designed. After several experimental analyses, the designed casting sorting robot gripper is characterized by strong adaptability and high robustness, with a maximum load capacity of 930 g and a maximum wrap angle of 296°, which can complete the gripping operation within 1 s, and the comprehensive gripping success rate reaches 96.4%. The casting sorting robot gripper designed in the paper can provide a reference for the design and optimization of various types of shaped workpiece gripping manipulators.

Numerical investigation to predict the impact of pre-heated air on the tar formation of cocoa pod husk gasification in a fixed bed downdraft gasifier

Tar production is a critical aspect of gasification thermochemistry, and it hinders the widening of biofuel utilisation in several applications. Both the gasifier configuration and the operating conditions influence the quantity of tar in PG. Since temperature plays a major role, this study examines the performance parameters of a gasifier across a spectrum of input air temperatures, from 27 to 627 °C, utilising computational fluid dynamics with species transport and porous media models. Since the deviation of numerical predictions from experimental results is within 10 %, the model's validity is confirmed. CO and H2 gas production increased from 19.23 % to 27.12 % and 9.23 %–16.2 %, respectively, over the tested air temperature range; however, the variation in methane content was not significant. Furthermore, the higher heating values of PG and cold gas efficiency were found to be 5–6.8 MJ/Nm3 and 65–69 %, respectively. The study also investigates reaction rates for gasification, combustion, and volatiles' breakdown under various operating conditions. Among the tar species studied, benzene is the most concentrated at 1.6 g/Nm3, followed by toluene at 0.9 g/Nm3, with naphthalene and phenol present in comparatively smaller amounts. Furthermore, the research indicates that an appropriate temperature of gasifying medium can control tar in PG.

Improving building energy efficiency through ventilated hollow core slab systems

The increasing desire for comfort and healthy indoor environment, as well as improvements in energy standards in recent years, have stressed the need to make an active use of the building mass to achieve the maximum energy saving This is why the application of ventilated hollow-core slab systems (VHCS) can be considered as one of the innovative approaches. These systems have precast concrete slabs with tubular voids directing ventilation air on its length. In the present study Solving this system numerically using the ANSYS fluent program to study the temperature distribution and air flow in the 3-D test model of the present study to determine the feasibility of applying this system in an arid climate especially in Iraq by checking the inlet velocity and temperature and to predict the impact of these operating parameters on human comfort and energy savings. The study aimed to provide a numerical analysis of a conditioned zone's temperature distribution using VHCS. The investigation was carried out on a scale model room of size (1 m × 1.2 m × 1 m) with a scale factor of ¼. Four distinct scenarios were examined: the first two cases occurred during a no-load time in the night when there were no internal or external loads and examined the effects of changes in inlet temperatures and air velocities. The remaining two scenarios were conducted during an occupied period with internal heat gain of 630 W/m2 and external heat gain of 800 W/m2 based on the SHGC for the summer season of Iraq. As previously demonstrated, setting the inlet velocity to 1 m/s resulted in an optimal temperature and velocity distribution in the main flow, irrespective of changes in the external and internal loads and temperatures of the supply core. The findings shown that input air velocity and temperature affect heat remove efficiency. In addition, numerical outcomes have also illustrated that the Thermal Active VHCS System, while used in combination with ventilation strategies, could indeed regulate the space conditions by cooling down the building's ceiling, thus eradicating stored heat. All investigations found VHCS systems suitable for air conditioning in dry and hot locations. The systems are known for their ease of use, simplicity, high performance, comfort, and energy savings. They can also reduce peak loads to boost structural energy efficiency.

Engineering EPS in Halomonas bluephagenesis leads to self-flocculation and filamentation for convenient downstream processing

The halophile Halomonas bluephagenesis has established itself as a cost-effective chassis in industrial bioproduction. However, downstream processing (DSP) expense is a persistent challenge. This study uses genetic knockout of exopolysaccharides (EPS-KO) in six industrially relevant H. bluephagenesis strains, each producing distinct polyhydroxyalkanoate (PHA), to evaluate their impact on reducing DSP costs. Remarkably, EPS-KO cells exhibited an unprecedented filamentous morphology, reaching lengths over 50 times (10–75 μm) that of standard cells. This unexpected behavior initially posed a challenge to industrial applicability due to rapid cell lysis under fermentation agitation. Systematic media supplementation of salt, carbon source, nitrogen, and essential minerals significantly influenced morphology, and tailored nutrient schemes that mitigated filamentation while maintaining production levels were designed. Scaled production in a 5000 L bioreactor demonstrated 85 % PHA and 96 g/L cell dry weight after 40 h fermentation, consistent with non-KO cells. During fermentation, EPS-KO enhanced cell-wall penetrability, reducing the need for high-cost γ-butyrolactone by 40 %. Additionally, a new innovative 5000 L FlipFlow bioreactor design cut rotation speed by 50 % and air input by 25 %. During DSP, centrifugation time decreased tenfold due to rapid cell self-flocculation (15–30 min), and the water and enzyme required for PHA purification was reduced by 30 % and 35 %, respectively. This study highlights the use of EPS-KO cells, a controlled media strategy, and low shear force FlipFlow bioreactor to successfully reduce DSP costs without sacrificing productivity. These novel findings represent a notable advancement in cost-saving strategies while presenting the intriguing discovery of media-controlled filamentous cell behavior.

A Soft Supernumerary Robotic Limb with Fiber-Reinforced Actuators

Supernumerary robotic limbs (SRLs) have great potentials to assist human in daily activities and industrial manufacturing by providing extra limbs. However, current SRLs have heavy and rigid structures that may threaten the operator safety; moreover, their limited degrees of freedom and movement modes are not suitable for complicated tasks. Although soft SRLs have exhibited advantages in structure compliance and flexible manipulation to address these problems, it remains challenging to accurately design the geometrical parameters to adapt to specific tasks, and accurate control is also required to realize the expected movement. Inspired by the biological characteristics of the octopus arm muscle fibers, fiber-reinforced actuators (FRAs) are employed to realize various motions, including extension, expansion, bending, and twisting; multiple FRAs are assembled to implement the SRL to achieve complex movement trajectories. The analytic model of the FRA is established to reveal the relationship between its deformation and geometrical parameters as well as input air pressures, which is validated with finite element simulation. Trajectory and payload optimization algorithms are proposed to optimally design the SRL and its control strategy with meeting the prescribed requirement of movement trajectory and payload capacity. Finally, experiments are conducted to validate the proposed robotic system.

Numerical Study on Prediction of Icing Phenomena in Fresh Air and Blow-by Gas Mixing Region of Diesel Engine under High Velocity of Intake Air Condition

The icing of an intake pipe that might happen in an actual vehicle was numerically predicted in this study. For various operating conditions, the amount of icing was estimated, and the variables influencing the amount of icing were identified. We compared the factors that affected icing: relative humidity, air temperature, and inlet velocity. Seven RPM and load conditions, an intake temperature range of 253–268 K, and a relative humidity range of 65–85% were used for the case studies. To verify the model accuracy, wind tunnel test results from chassis dynometer tests were compared to the data from simulations. The flow analysis was performed using the numerical analytical tool ANSYS Fluent (2019 R1), while the amount of condensed water and icing was predicted using FENSAP-ICE, a program that analyzes and predicts icing phenomena under mechanical systems. The ambient temperature, relative humidity, and inlet air velocity had the biggest effects on the icing rate. The total amount of icing increased for similar BB and input air velocities. When the input air and BB velocities are the same, the variables influencing icing are the ambient temperature and relative humidity. The amount of ice was less affected by outside temperature and relative humidity when the rpm was high, and the inlet air velocity also had an impact.

Catalytic Light-Driven Strategy for Transforming Oximes to Carbonyls.

Oxime and carbonyl functional groups serve as powerful chemical hubs for constructing complex synthetic targets and valuable molecular scaffolds. In furthering this value, we report a photopromoted catalytic deoximation protocol for converting oximes and their derivatives to carbonyl functional groups. This strategic approach benefits from the use of renewable light energy input and ambient air conditions, in addition to demonstrating good substrate scope, functional group tolerance, and product yields. In offering, insights into these reactivity mechanistic studies are communicated, and the value of this protocol is further shown through one-pot operations.

Heat Convection in a Channel-Opened Cavity with Two Heated Sources and Baffle

This study employs COMSOL software v 5.6 to investigate a novel approach to heat transfer via mixed convection in an open hollow structure with an unheated 90° baffle elbow. Two 20 W heat sources are strategically positioned on the cavity’s bottom and right-angled wall for this research. Notably, the orientation of the baffle perpendicular to the airflow is used to direct external, unrestricted flow into the square cavity. The research investigates a range of air velocities (0.1, 0.5, 1.0, and 1.5 m/s) and the intricate interaction between input air velocity, dual heated sources, and the presence of a right-angle baffle on critical thermodynamic variables, such as temperature distribution, isotherms, pressure variation, velocity profile, air density, and both local and mean Nusselt numbers. Validation of the applicable computational method is achieved by comparing it to two previous studies. Significant findings from numerical simulations indicate that the highest velocity profile is in the centre of the channel (2.3–2.68 m/s at an inflow velocity of 1.5 m/s), while the lowest profile is observed along the channel wall, with a notable disruption near the inlet caused by increased shear forces. The cavity neck temperature ranges from 380 to 640 K, with inflow air velocities varying from 0.1 to 1.5 m/s (Re is 812 to 12,182), respectively. In addition, the pressure fluctuates at the channel-cavity junction, decreasing steadily along the channel length and reaching a maximum at the intake, where the cavity neck pressure varies from 0.01 to 2.5 Pa with inflow air velocities changing from 0.1 to 1.5 m/s, respectively. The mean Nusselt number exhibits an upward trend as air velocity upon entry increases. The mean Nusselt number reaches up to 1500 when the entry air velocity reaches 1.5 m/s. Due to recirculation patterns, the presence of the 90° unheated baffle produces a remarkable cooling effect. The study establishes a direct correlation between input air velocity and internal temperature distribution, indicating that as air velocity increases, heat dissipation improves. This research advances our understanding of convective heat transfer phenomena in complex geometries and provides insights for optimising thermal management strategies for a variety of engineering applications.

Locomotion control of a rigid-soft coupled snake robot in multiple environments

The versatile motion capability of snake robots offers themselves robust adaptability in varieties of challenging environments where traditional robots may be incapacitated. This study reports a novel flexible snake robot featuring a rigid–flexible coupling structure and multiple motion gaits. To better understand the robot’s behavior, a bending model for the soft actuator is established. Furthermore, a dynamic model is developed to map the relationship between the input air pressure and joint torque, which is the model base for controlling the robot effectively. Based on the wave motion generated by the joint coupling direction function in different planes, multiple motion gait planning methods of the snake-like robot are proposed. In order to evaluate the adaptability and maneuverability of the developed snake robot, extensive experiments were conducted in complex environments. The results demonstrate the robot’s effectiveness in navigating through intricate settings, underscoring its potential for applications in various fields.