kPa Pressure Research Articles

Experimental Verification of a Compressor Drive Simulation Model to Minimize Dangerous Vibrations

The article highlights the importance of analytical computational models of torsionally oscillating systems and their simulation for estimating the lowest resonance frequencies. It also identifies the pitfalls of the application of these models in terms of the accuracy of their outputs. The aim of the paper is to control the dangerous vibration of a mechanical system actuator using a pneumatic elastic coupling using different approaches such as analytical calculations, experimental measurement results, and simulation models. Based on the known mechanical properties of the laboratory system, its dynamic model in the form of a twelve-mass chain torsionally oscillating mechanical system is developed. Subsequently, the model is reduced to a two-mass system using the method of partial frequencies according to Rivin. The total load torque of the piston compressor under fault-free and fault conditions is simulated to obtain the amplitudes and phases of the harmonic components of the dynamic torque. After calculating the natural frequency and the natural shape of the oscillation, the Campbell diagram is processed to determine the critical revolutions. There is a pneumatic flexible coupling between the rotating masses, which changes the dynamic torsional stiffness. The dynamic torque curves transmitted by the coupling are compared with different dynamic torsional stiffnesses during steady-state operation and one cylinder failure. The monitored values are the position of the critical revolutions, the natural frequency, the natural shape of the oscillation, and the RMS of the dynamic load torque. The experimental model is verified by the simulation model. The accuracy of the developed simulation model with the experimental data are apparently very good (even more than 99% of the critical revolutions value obtained by calculation); however, it depends on the dynamic stiffness of the coupling. In this study, a detailed, comprehensive approach combining analytical procedures with simulation models is presented. Experimental data are verified with simulation results, which show a good agreement in the case of 700 kPa coupling pressure. The inaccuracy of some of the experiments (at 300 and 500 kPa pressures) is due to the interaction of the coupling’s apparent stiffness and the level of the damped vibration energy in the coupling, which is manifested by its different heating. Based on further experiments, a solution to these problems will be proposed by introducing this phenomenon effectively into the simulation model.

Facile, scalable and Substrate-Independent omniphobic surface

Omniphobic surfaces have a very wide range of applications. However, limited by substrate material and/or fabrication processes, scalable synthesis of robust omniphobic surfaces with universality and versatility remains challenging for both academia and industry. Here, we present a facile and scalable slippery omniphobic surface (FSSOS) based on the straightforward blending and dip/spray-coating of polysilazane (PSZ) and minute low surface energy silane under room temperature. Water shows a contact angle hysteresis (CAH) of 18°, and the overall trend across all tested solvents suggests a relatively low CAH (＜10°), further enhancing its surface omniphobicity. The one-step synthesis protocol is cost-effective, substrate-independent, and does not require curing aids such as UV irradiation or heat. The FSSOS achieves multi-liquid omni-repellency with chemical and mechanical durability under various harsh exposure conditions. The CAH remains stable even after exposure to 4 m/s water jet impact for 8 h, 130 W ultrasonic vibration for 250 min, 10 kPa pressure tape-peel test for 250 cycles, heating at 250 °C for 10 min, and 205 mW/cm2 UV irradiation for 28 days. This approach highlights a functional design of liquid-repellent surfaces for numerous real-world applications.

Comprehensive analysis of the effects of cooking conditions on the quality, sensory characteristics, and flavor profile of glutinous rice chicken, a Chinese traditional poultry meat product

This study investigated the effects of cooking conditions on cooking loss, texture, and sensory attributes of glutinous rice chicken (GRC), a popular Chinese poultry dish. We compared the nutritional and sensory profiles of GRC prepared under optimal conditions (GRC-OP) with those of a commercial product (CG). Cooking time, power, and pressure significantly affected the shear force, hardness, and sensory qualities of GRC. The optimal parameters were determined using an orthogonal design: 20 min cooking time, 1000 watts power, and 60 kPa pressure. Gas chromatography/mass spectrometry and E-nose analyses showed that GRC-OP had a volatile profile similar to that of CG but with higher levels of specific compounds, including heptanal, 2-heptenal, octanal, hexanol, octanol, and 1-nonen-4-ol. GRC-OP also exhibited superior umami, salty, and rich tastes, and higher amino acid content, particularly Asp, Glu, Thr, Ser, Ala, Val, Met, and Ile. These findings provide crucial data for optimizing the quality and nutritional value of GRC in the meat industry.

Cleanroom-free fabrication of flexible capacitive pressure sensors using paintable silver electrodes on stationery paper and random microstructured polydimethylsiloxane dielectric layer

Abstract In this work, we propose a facile, low-cost, and cleanroom-free approach for fabricating flexible capacitive pressure sensors based on paintable Ag electrodes on stationery paper substrates (Ag–paper electrodes) and a random microstructured polydimethylsiloxane (PDMS) dielectric layer transferred from emery paper. COMSOL Multiphysics simulations and experimental investigations suggest that the pressure sensor with random microstructured PDMS dielectric layer performs better than the sensor with ordered micropyramidal dielectric layer. The developed Ag–paper electrode and random microstructured PDMS dielectric layer-based pressure sensors are workable in a wide pressure range (up to 630 kPa) and exhibit a high sensitivity of 0.132 kPa−1 up to 1 kPa, low hysteresis (6.6%) with loading–unloading of ∼500 kPa pressure, high stability during a ∼5250 cyclic test, and the ability to sense a low pressure of ∼27 Pa. The developed sensor also successfully transduces arterial pulse wave forms when it is properly attached to the wrist. Using the proposed process, a flexible capacitive pressure sensor matrix of 4 × 4 array is also successfully developed for single- and multiple-point pressure mapping with minimal cross-talk. The proposed sensor process is simple and inexpensive to implement, and offers spatial pressure mapping for e-skin applications.

Home-based long-term physical endurance and inspiratory muscle training in children and adults with Fontan circulation.

Regular physical activity is highly recommended for patients with Fontan hemodynamics. Our aim was to investigate the effects of a long-term individualized home-based endurance training (IHET) on a bicycle ergometer in combination with inspiratory muscle training (IMT) in pediatric and adult patients after Fontan palliation. Additionally, factors influencing the trainability of Fontan palliated patients were analyzed. From 2018 to 2021 a single-center prospective study was performed initially including 25 Fontan palliated patients. During study period nine patients were excluded due to incompliance. A Magbike® bicycle ergometer (DKN Technology, France) was used for IHET and a POWERbreathe® Medic plus device (HaB GmbH, Germany) was utilized for the IMT. Over the study period, bike training was increased from 90 min of basic endurance training per week to additional 25 min of interval training per week. IMT consisted of 30 breaths per day for 6-7 days per week with pressure adaption over time. Patients underwent cardiopulmonary exercise testing (CPET) and body plethysmography including measurement of respiratory muscle strength at baseline and at follow-up examinations at 4, 10 and 22 months. Follow-up examinations were completed by 18/25 patients (72.0%) at 4 and 10 months and 16/25 patients (64.0%) at 22 months. Median exercise capacity slightly increased by 0.13 W/kg from baseline to last follow-up (p = 0.055, 95%CI: 0.0-0.36). However, a significant increase of oxygen pulse of 0.7 ml/beat (p = 0.006, 95%CI: 0.38-2.22) was detectable. IMT significantly improved respiratory function with an increase of inspiratory vital capacity (VCin/reference) by 4.0% (p = 0.016, 95%CI: 0.8-8). Median maximal inspiratory pressure increased by 1.2 kPa (p = 0.003, 95%CI: 0.64-3.19) and expiratory pressure by 1.5 kPa (p = 0.036, 95%CI: 0.08-2.29). No adverse events or unplanned interventions occurred during the study. Patients' subjective quality of life did not significantly change over the study period. In Fontan palliated patients, IHET in combination with IMT leads to a significant increase in oxygen pulse, inspiratory vital capacity as well as median maximal inspiratory and expiratory pressure but not to significant improvement of quality of life. Fontan patients should be encouraged to perform regular home-based exercise training.

Foundational Engineering of Artificial Blood Vessels' Biomechanics: The Impact of Wavy Geometric Designs.

The design of wavy structures and their mechanical implications on artificial blood vessels (ABVs) have been insufficiently studied in the existing literature. This research aims to explore the influence of various wavy geometric designs on the mechanical properties of ABVs and to establish a foundational framework for advancing and applying these designs. Computer-aided design (CAD) and finite element method (FEM) simulations, in conjunction with physical sample testing, were utilized. A geometric model incorporating concave and convex curves was developed and analyzed with a symbolic mathematical tool. Subsequently, a total of ten CAD models were subjected to increasing internal pressures using a FEM simulation to evaluate the expansion of internal areas. Additionally, physical experiments were conducted further to investigate the expansion of ABV samples under pressure. The results demonstrated that increased wave numbers significantly enhance the flexibility of ABVs. Samples with 22 waves exhibited a 45% larger area under 24 kPa pressure than those with simple circles. However, the increased number of waves also led to undesirable high-pressure gradients at elevated pressures. Furthermore, a strong correlation was observed between the experimental outcomes and the simulation results, with a notably low error margin, ranging from 19.88% to 3.84%. Incorporating wavy designs into ABVs can effectively increase both vessel flexibility and the internal area under pressure. Finally, it was found that expansion depending on the wave number can be efficiently modeled with a simple linear equation, which could be utilized in future designs.

A numerical model for predicting the wear of a piston ring/cylinder liner at the top dead center

The cylinder liner-piston ring interface is a critical friction pair in diesel engines, and liner wear can significantly affect engine operation. This study proposes a numerical simulation model under variable operating conditions to quantitatively predict wear at the top dead center (TDC) of the liner, and verifies the model's accuracy. It reveals the influence patterns of engine speed, ambient temperature, and ambient pressure on cylinder liner wear. The research demonstrates good qualitative and quantitative agreement between the wear simulation model and experimental data, particularly with high precision near TDC. Further analysis shows that overall TDC wear depth increases with higher engine speeds. Specifically, wear at 1500 r/min is relatively lower compared to 1300 r/min. Moreover, TDC wear depth exhibits a trend of initially decreasing and then increasing with decreasing ambient pressure and increasing ambient temperature, reaching its minimum at 70 kPa pressure and 25°C temperature.

Innovative air mattress for the prevention of pressure ulcers in neonates.

Pressure ulcers (PUs) severely impact health outcomes in neonatal intensive care, with up to 28% prevalence and doubled mortality rates. Due to their only partially developed stratum corneum, neonates are highly susceptible to PUs because of a lack of adequate support surfaces. The occipital region of the head and hip are the main risk areas due to immobility and newborn body proportions. The main goal of the study was to investigate the impact of reduction in local pressure in these body areas by two air mattress designs and different filling states. Two innovative air-filled mattress prototypes (prototype 1 and prototype 2), consisting of three different segments (head, trunk and feet regions), were developed to reduce local interface pressures by optimising pressure distribution, and were assessed with three air pressure filling states (0.2kPa, 0.4kPa and 0.6kPa). A baby doll was used to investigate pressure distribution and local pressure impact. It measured 51cm and the weight was modified to be 1.3kg, 2.3kg and 3.3kg, representing premature to term newborn weights, respectively. A specialised foam mattress and an unsupported surface were considered as controls. The interface pressures at the hip region for newborn models could be reduced by up to 41% with mattress prototype 1 and 49% with prototype 2 when filled with 0.2kPa air pressure. It was found that the size and the pressure inside air segments was crucial for interface pressure. Our results demonstrated that air mattresses achieved lower interface pressures compared to conventional support surfaces, and that the benefit of the air mattresses depended on their filling status. The importance of using innovative, segmented designs that were tailored to meet the specific needs of highly vulnerable paediatric patients was demonstrated.

An electropermanent magnet valve for the onboard control of multi-degree of freedom pneumatic soft robots

To achieve coordinated functions, fluidic soft robots typically rely on multiple input lines for the independent inflation and deflation of each actuator. Fluidic actuators are controlled by rigid electronic pneumatic valves, restricting the mobility and compliance of the soft robot. Recent developments in soft valve designs have shown the potential to achieve a more integrated robotic system, but are limited by high energy consumption and slow response time. In this work, we present an electropermanent magnet (EPM) valve for electronic control of pneumatic soft actuators that is activated through microsecond electronic pulses. The valve incorporates a thin channel made from thermoplastic films. The proposed valve (3 × 3 × 0.8 cm, 2.9 g) can block pressure up to 146 kPa and negative pressures up to –100 kPa with a response time of less than 1 s. Using the EPM valves, we demonstrate the ability to switch between multiple operation sequences in real time through the control of a six-DoF robot capable of grasping and hopping with a single pressure input. Our proposed onboard control strategy simplifies the operation of multi-pressure systems, enabling the development of dynamically programmable soft fluid-driven robots that are versatile in responding to different tasks.

Innovative approach in pistachio processing: Effect of explosion puffing drying on the quality characteristics of dried pistachios

The study examined the impact of explosion puffing (EP) drying at varying pressure levels (70, 140, and 210 kPa) followed by vacuum drying for 85, 100, and 115 min on pistachio quality. EP drying significantly reduced drying time, moisture content, and water activity. Samples dried at the pressure of 210 kPa for 85 min (P3T1) had a crispy texture of the kernel (p < 0.05). EP drying decreased the density of the pistachio kernels (p < 0.05), which led to a porous structure and a more favorable texture. Peroxide value (POV) decreased at lower pressure and drying time (p < 0.05), and the lowest POV was observed at 70 kPa for 100 min (P1T2). The EP had no significant effects on the free fatty acid (FFA), dimensions, and shell splitting degree of pistachios (p < 0.05). Among the sensory attributes, the sensory scores of texture and overall acceptance were significantly higher than those of the control (p < 0.05). In general, the textural and sensory characteristics of pistachio samples and the shorter drying time (2.5 times) in the EP with the 210 kPa pressure for 85 min (P3T1) were better than the control sample and other EP treatments, and it is suggested as a new drying method for pistachio processing.

Fabrication of high performance BaSnO3/PVDF piezoelectric nanogenerator through high surface area BaSnO3 nanoparticle assisted β-phase stabilization of PVDF

Piezoelectric nanogenerators (PENGs) are becoming increasingly popular for energy generation and their use in smart electronics. In this study, a barium stannate (BaSnO3)-doped polyvinylidene fluoride (PVDF)-based PENG has been fabricated for the first time. The β-phase of PVDF was stabilized by optimizing the doping of BaSnO3 nanoparticles without the need for external electrical poling. The high surface area of the BaSnO3 nanoparticles promotes the nucleation of the polar β-phase in PVDF through electrostatic interaction. A low-cost solution casting method was used to prepare flexible BaSnO3/PVDF nanocomposite containing 5 wt% BaSnO3, which was then shaped and sandwiched between copper electrodes and protected with a thin PDMS layer to create the final PENG. The fabricated PENG can generate up to ∼41 V of voltage, ∼1.51 µA of current and ∼18.1 µW/cm2 of power density when ∼15.7 kPa pressure is applied by a human finger. The PENG can also charge capacitors, power up 16 LEDs in a series connection, and power other small electronics such as wristwatches, speakers, and calculators. Additionally, the PENG can activate the electrochromic material methyl viologen, which is commonly used in smart window applications.

Accessible melt electrowriting three-dimensional printer for fabricating high-precision scaffolds

Melt electrowriting (MEW) is an established 3D printing technology for producing high-resolution scaffolds for tissue engineering. Commercial MEW devices are expensive while having limited processing capabilities, which limits their accessibility and widespread use. Herein, we report an easy-to-assemble and inexpensive ($2000) MEW printer based on an off-the-shelf automated dispensing machine with user-friendly controls and a custom-designed MEW printhead capable of printing polymers with a melting point of up to 260 °C. Using the gold standard printable material, poly(ε-caprolactone) (PCL), this printer can deposit 3 μm diameter fibers at 50 μm spacing, demonstrating that the highest quality of scaffolds can be produced on the low-cost MEW system. Stability in printing is improved by maintaining a relative humidity of 30–35 %, ensuring nozzle conditions are optimal, and minimizing bubbles in the polymer melt. Key printing parameters such as a 3 kV applied voltage, 75 °C heating temperature, 100 kPa air pressure, and 30 G nozzle size are critical for high accuracy, achieving 100 μm fiber spacing and layer stacking up to 30 layers without fiber breakage. The printer effectively creates complex scaffold geometries, showcasing its precision and suitability for advanced tissue engineering applications. Overall, this study promotes low-cost MEW technology by establishing a guideline on building an accessible but capable MEW printer and providing a crucial experimental foundation toward achieving high-accuracy scaffolds.

Low-Temperature Rapid Polymerization of Intrinsic Conducting PAD/OC Hydrogels with a Self-Adhesive and Sensitive Sensor for Outdoor Damage Repair and Detection.

Intrinsic conducting hydrogels fabricated in situ at low temperatures with self-adhesive properties and excellent flexibility hold significant promise for energy applications and outdoor damage repair. However, challenges such as low polymerization rate and self adhesion, insufficient ionic conductivity, inflexibility, and poor stability under extreme cold conditions have hindered their utilization as high-performance sensors. In this study, we designed an intrinsic conducting hydrogel (PADOC) composed of acrylic acid, acryloyloxyethyltrimethylammonium chloride, N,N'-methylenebis(2-propenamide), self-fabricated oxidized curdlan (OC), and a water/glycerol binary solvent. The novel hydrogel exhibited rapid gelation (30 s) at 0 °C facilitated by the promotion of OC, without the need for external energy input. Our findings from FT-IR, NMR, XPS, XRD, EPR spectra, MS, and DSC analyses revealed that OC underwent selective oxidation via the evolved Fenton reaction at 30 °C, serving as bioaccelerators for PAD polymerization. Due to OC's reductive structure and increased solubility, the reaction activation energy of the PAD polymerization reaction significantly reduced from 103.2 to 54.4 kJ/mol. PADOC ionic hydrogels demonstrated an electrical conductivity of 1.00 S/m, 0.7% low hysteresis, 39.6 kPa self-adhesive strength, and 923% strain-at-break and kept even at -20 °C owing to dense hydrogen and ionic bonds between PAD and OC chains. Furthermore, PADOC ionic hydrogels exhibited antifatigue properties for 10 cycles (0-100%) due to electrostatic interactions and hydrogen bonding. Remarkably, using a self-designed device, the rapid polymerization of PADOC effectively repaired copper pipeline leakage under 86 kPa pressure and detected 1% strain variation as a strain sensor. This study opens a new avenue for the rapid gelation of self-adhesive and flexible intrinsic conducting hydrogels with robust sensor performance.

Study on the effects of medium-low pressure and oxygen concentration on positive streamer based on a two-dimensional fluid model

We studied positive streamers with a 5 mm gap under 20–101 kPa pressure and 1%–31% O2 concentrations conditions using a 2D axisymmetric fluid model based on local field approximation. As the pressure decreases from 101 kPa to 20 kPa, the axial reduced electric field, the mean electron energy and the electron diffusion coefficient increase, which leads to the acceleration of the streamer propagation velocity and the increase of the streamer channel radius. The opposite change of ionization cross section and gas molecular density caused by the decrease of pressure leads to the non-monotonic change of the peak of net ionization rate. At medium-low pressure, there is a wider ionization region at the streamer head. As the O2 concentration decreases from 31% to 1% in N2/O2, the streamer propagation velocity decreases. When the O2 concentration drops to 1%, the streamer velocity decreases with a descent gradient of nearly 4 times, compared to 11% O2. Based on the space charge effect and chemical reaction rate, a possible mechanism is proposed to explain the abrupt change in the streamer velocity.

Experimental study of air leakage of reinforced concrete panel with cracks

Evaluation of the leakage rate is necessary for infrastructure where hermetic performance holds critical importance. This study conducted a test to evaluate the air leakage rate of cracked reinforced concrete panels. Hollow beam specimens with an air chamber in the web were prepared to provide a relatively simple setup for airtight pressure testing under 200 kPa pressure. While testing, the lower flange of the beam specimen was subjected to tension cracking under transverse loading, and air pressure was applied to the air chamber of the beam to measure the air leakage rate through the flange plate as the magnitude of loading increased. The test variables were the differential air pressure, flange plate thickness, and reinforcement ratio. The test results showed that the leakage rate increased in proportion to the differential pressure. When the reinforcement ratio increased from 0.7 to 1.3 %, the leakage rate decreased by 90 %. When the plate thickness increased from 75 to 100 mm, the leakage rate decreased by 91 %. The analysis of the test results showed that the leakage rate was proportional to the cube of the crack width (R2 = 0.91–0.95), which agreed with existing prediction models. When the crack width at rebar location was used, the existing models showed the best predictions for test results. This result indicates that to accurately predict the air leakage rate of reinforced concrete members, the critical crack width at the location of reinforcement (i.e. the smallest crack width in the member thickness) is more important than the crack width at the member surface.

Direct detection of monoterpenes in evacuated air atmospheres by glow discharge plasma source for mass spectrometry

Some compounds, including the monoterpenes, are difficult to be analyzed by chemical ionization mass spectrometry (CI-MS) mass spectrometry because of having distinct chemical features of unsaturated bonds in relatively large molecule, which is responsible for occurring fragmentation of molecular ions. A direct detection of monoterpenes, including monocyclic, bicyclic and oxygenated (acyclic), was carried out using a soft plasma ionization (SPI) source combined with a q-mass spectrometer (q-MS). Detectable signals for monoterpenes were examined in an ambient air discharge plasma when varying the discharge parameters, such as discharge pressure (0.4–3.0 kPa) and sample/carrier pressure ratio (R = 5–100%). Furthermore, to consider the ionization reactions in detail, nitrogen gas was also used as the discharge gas (carrier gas). Monoterpenes, including cross-linked bicyclic (α-pinene and β-pinene) and oxygenated (linalool, geraniol, nerol and eucalyptol), in which their simple spectrum patterns can be obtained with little or no fragmentation at an ambient air pressure of several kPa, has successfully conducted by the pulsed dc SPI-MS. To our knowledge, this is the first report demonstrating that the spectrum pattern of monoterpenes could be directly detected without any complicated fragmentation of analyte ions in the SPI source.

Highly transparent and stretchable multi-layered capacitive film sensor with flexible dot and micro-pillar array for small pressure sensing

The research aim is to develop multilayered capacitive film pressure sensors with dot and micro-pillar array, having high transparency, sensitivity, and flexibility by utilizing polydimethylsiloxane (PDMS) and the conductive polymer, poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS)" as the primary components. The results reveal that the transmittance values of the multilayered capacitive film sensors with dot array vary with their thickness, achieving values of 76.39 %, 72.06 %, and 65.39 % at a center wavelength of 550 nm and demonstrating the effective capacitive sensing response in the pressure range of 0–750 kPa. Notably, the micro-pillar array multilayered capacitive film sensor shows high sensitivity of 0.025 kPa−1 in the pressure range of 0–100 kPa and a clear trend of capacitance change around 60 kPa. It achieves the highest sensitivity of 0.05 kPa−1 within the 0–10 kPa pressure range. The stability of the multilayered capacitive film sensor is examined by applying compressive forces of 0.5 N, 1.0 N, and 1.5 N in a suspended state, resulting in a maximum rate of change reaching 104.7 % compared to the initial capacitance value. Additionally, the multilayered capacitive film sensors demonstrate good stability under cyclic pressures of 0.5 N, 1.0 N, and 1.5 N. The novel multilayered capacitive film sensor offers specific promising potentials for various applications in the fields of wearable, medical devices, and human-machine interfaces.

Multi-objective parameter optimization design of tapered-type manifold/variable cross-section microchannel heat sink

Manifold microchannel heat sinks (MMCHS) have been widely used in the thermal management of high heat flux electronic devices. To improve the temperature uniformity of MMCHS and reduce the hot spot temperature, a tapered-type manifold/variable cross-section microchannel heat sink (TMVC-MCHS) is proposed in this study. Key parameters affecting the heat transfer performance of TMVC-MCHS were first investigated numerically. The results indicate that the width inclination ratio (αw,in) of the inlet manifold has a greater influence on the coolant flow distribution than the height inclination ratio (αh,in), with a ratio of more than 2.5. In addition, the microchannel inclination (β) and width ratio (ε) affect significantly the fluid flow and heat transfer. To further improve the cooling effect of the heat sink, this study adopted XGBoost and multi-objective genetic algorithm (NSGA-II) to optimize the structure. The maximum temperature of the substrate (Tmax) and the total pressure drop (ΔP) are the optimization objectives. Besides, the compromise solution (αw,in = 0.40, β = 0.63 and ε = 0.52) was determined by TOPSIS combined with the entropy weight method which was validated by the CFD method with an error margin of only 3 %. Finally, Compared to MMCHS, the temperature field distribution uniformity of TMVC-MCHS is significantly improved. The maximum bottom surface temperature is drastically reduced from 337.79 K to 320.01 K, and the temperature difference is reduced from 17.5 K to 3.5 K, at the cost of only a 3.5 kPa pressure rise. For inlet flow rates ranging from 1 m/s to 2.5 m/s, the TMVC-MCHS exhibits a hydrothermal performance factor (PEC) improvement of over 35 %, indicating superior comprehensive performance.

Design and Scalable Fast Fabrication of Biaxial Fabric Pouch Motors for Soft Robotic Artificial Muscle Applications

Soft pouch motors, engineered to mimic the natural movements of skeletal muscles, play a crucial role in advancing robotics and exoskeleton development. However, the fabrication techniques often involve multistage processes; they lack soft sensing capabilities and are sensitive to cutting and damage. This work introduces a new textile‐based pouch motors with the capacity for biaxial actuation and capacitive sensory functions, achieved through the application of computerized knitting technology using ultrahigh molecular weight polyethylene yarn (Spectra) and conductive silver yarns. This method enables the rapid and scalable mass fabrication of robust pouch motors. The resulting pouch motors exhibit maximum lifting capacity of 10 kg, maximum contraction of 53.3% along the y‐axis, and transverse extension of 41.18% along the x‐axis at 50 kPa pressure. Finite element analysis closely matches the experimental data. The capacitance signals in relation to contraction motion are well suited for detecting air pressure levels and hold promise for applications requiring robotic control. Notably, it effectively elevates an ankle joint simulator at a 20° angle, highlighting its potential for applications such assisting individuals with foot drop. This study presents a practical demonstration of the soft ankle exosuit designed to provide lifting support for individuals facing this mobility challenge.

Influence of the curing stress effect on the stiffness degradation curve of a silt stabilized with lime and cement

This study investigated the shear modulus degradation curves of reconstituted stabilized soil specimens and their evolution during curing up to 270 days. An experimental protocol is proposed to get as close as possible to the in situ curing conditions of a chemically (lime and hydraulic binder) and mechanically (compaction) improved soil placed in a high-rise geotechnical structure. Innovative solutions now make it possible to build high embankments (> 10 m) in stabilized soil. In the laboratory, a silty soil stabilized with 1% lime and 5% hydraulic binder, which is a classic treatment for linear projects, was cured with a pressure of 300 and 500 kPa, corresponding to a depth in the embankment of 15 and 25 m. These structures are expected to have high mechanical performance and must be able to withstand very small deformations (earthquakes, traffic loads). Experimental campaigns are performed in laboratory using torsion tests with a resonant column apparatus (RCA) to obtain the shear modulus G as a function of distortion. A comparison was made between normalized curing conditions (temperature of 20 °C and atmospheric pressure) and curing with confining pressure (temperature of 20 °C and 300 or 500 kPa pressure). For this aim, 74 torsional RCA tests were conducted on 16 compacted soil specimens. These showed that the curing pressure, applied just after compaction, brings the expected properties more quickly and confers superior properties of around 15% in the long term. A power law was proposed to estimate the Gmax of a stabilized silt specimen as a function of time, based on the Gmax measured during the first two days of curing. This empirical law gives the Gmax over the long term (270 days) for curing with or without confining pressure. Pioneering a combined curing-testing RCA approach, this study elucidates the short and long-term behavior of stabilized silts under realistic curing conditions.