Search Results (222)

In battery systems, external mechanical compression is commonly applied to pouch/prismatic cells to improve their electrical performance and mechanical integrity. However, cell clamping can hinder system heat rejection by introducing an additional thermal insulation layer. A novel battery clamping scheme was designed with reduced contact area to explore the system thermal behaviour under different cooling regimes. Experimental data obtained from battery characterisation and performance tests is analysed with a thermal-coupled equivalent circuit model to quantify changes in cell impedance and system thermal properties. By reducing the clamping area by 70%, the temperature rise of the cell was decreased by 0.5 °C in comparison to the reference condition of a cell with no clamping during a 1C discharge under natural convection. Under immersion cooling using BOT2100 dielectric liquid, the thermal benefit was amplified, resulting in temperature reductions of 0.9 °C at 1C and 4 °C at 3C. The principal conclusion of this work is that reshaping the clamping plate has the potential to reduce ohmic heating by lowering battery internal resistance, which outweighs the additional thermal resistance introduced by partial surface coverage. This novel experimental approach demonstrates the potential to improve battery thermal management through geometry-optimised cell clamping, particularly for high-power applications, and further directs the community towards cell clamping solution designed to optimise both thermal and mechanical cell performance. Full article

In karst tunnel engineering, water-filled cavities located above the tunnel crown, under the combined effects of excavation disturbance and hydraulic pressure, are prone to triggering water and mud inrush disasters. The thickness of the water-resisting rock layer is therefore a key factor controlling the stability of the surrounding rock. To address the difficulty in accurately characterizing the mechanical behavior of the crown of horseshoe-shaped tunnels using conventional circular plate or beam models, this study innovatively develops an explicit analytical model for the minimum safe thickness of the water-resisting rock layer based on clamped elliptical thin plate theory and Kirchhoff plate theory, incorporating the influence of cross-sectional geometry. Parametric sensitivity analysis indicates that both karst water pressure and tunnel crown height significantly amplify the required minimum safe thickness, whereas an increase in the tensile strength of the surrounding rock effectively reduces the thickness demand. Specifically, when the karst water pressure increases from 2.5 MPa to 4.5 MPa, the minimum safe thickness rises from 7.5 m to 10.0 m, showing an approximately linear growth trend. The analytical model is further validated through numerical simulations under different “water pressure–thickness” conditions. The results demonstrate that at the calculated recommended thickness, the surrounding rock achieves stable convergence after excavation. High tensile stress and elevated pore pressure zones are mainly concentrated near the tunnel crown, without the formation of through-going tensile failure. Engineering application indicates that the proposed model can provide a quantitative basis for the design of water-resisting rock layer thickness and the assessment of water inrush risk in karst tunnels. Full article

PDMS SlipChips are vital for precision medicine, but their performance often degrades when solutions leak or air pockets become trapped between layers. These failures stem from the inherent stickiness of PDMS and uneven surface contact, as the sliding nature of the device prevents permanent sealing. This work addresses these technical hurdles by integrating magnetic clamping with oil-infused lubrication and refined microwell geometries. A 3D-printed magnetic fixture maintains steady contact pressure during operation, while custom-made microstages provide the precise control needed to align microwells across the x–y plane. By allowing the porous PDMS to absorb silicone oil, we created a stable lubricating interface that prevents leakage and reduces friction without sacrificing mobility. We found that a microwell-to-channel width ratio of five substantially suppresses bubble formation compared with narrower designs. These enhancements ensure the generation of consistent, discrete concentration gradients and establish a reliable platform for high-throughput assays using minute sample volumes. Full article

This article presents the design and detailed characterization of a new supersonic wind tunnel at the Aerospace Laboratory for Lasers, ElectroMagnetics, and Optics of Texas A&M University, tailored for optical diagnostic development and sub-scale fundamental compressible fluid dynamics research. A Ludwieg tube tunnel architecture was selected due to its robustness, versatility, and low operational costs. The tunnel consists of a 50-foot-long driver tube constructed from modular Tri-Clamp spools, a Mach 4 nozzle with 3 in. exit diameter configured as a free jet, and a fast-acting valve with 14 ms opening time for high-duty-cycle operation. Such construction proved to be a robust, compact, and affordable solution for academic applications. Characterization methods consisted of simultaneous high-speed dot-schlieren, total and static pressure measurements, and femtosecond laser electronic excitation tagging. Average flow velocity for the first steady-state test time was measured via FLEET at (668.0 ± 5.7) m/s. The Mach number was calculated based on the angles of the attached oblique shocks formed near the 30° cone model. Calculated Mach number was repeatable from run to run and had small oscillations near the average value of 3.96 ± 0.03. Based on the simultaneously measured velocity and Mach number, the static temperature was calculated to be between (68.6 ± 0.3) K and (66.3 ± 0.3) K throughout the 400 ms test time, completely defining the thermodynamic state of the generated freestream flow. Full article

The maxillary sinus is frequently implicated in facial pain syndromes arising from infection, neoplasia, dental procedures, and, importantly, migraine, which can mimic “sinus headache” and contribute to misdiagnosis and inappropriate antibiotic use. Despite the clinical burden of chronic maxillary sinus pain, the sensory neuron subtypes that convey nociceptive and mechanosensory signals from the sinus mucosa remain incompletely defined. In this study, trigeminal ganglion (TG) neurons innervating the maxillary sinus (maxillary sinus TG neurons) were retrogradely labeled with the fluorescent dye DiD in mice and characterized using ex vivo patch-clamp electrophysiology and single-cell RT-PCR. Maxillary sinus TG neurons were found to be predominantly small-diameter, C-afferent nociceptors with electrophysiologic features including high thresholds, repetitive firing, and broad action potentials. Notably, maxillary sinus TG neurons formed a distinct molecular and functional subgroup: they expressed Nav1.9, while showing minimal Nav1.8 expression and limited overlap with Nav1.8-positive nociceptor populations. A majority of maxillary sinus TG neurons were mechanically responsive, generating mechanically activated currents with heterogeneous adaptation profiles, and a subset expressed the mechanoreceptor Piezo2. Collectively, these findings identify maxillary sinus TG neurons as a specialized population of Nav1.9-enriched C-afferent nociceptors with mechanosensitive properties, providing a mechanistic framework for pressure-evoked sinus pain. This work advances the neurobiological basis of sinus-related pain and suggests that Nav1.9 and mechanoreceptor pathways may be potential therapeutic targets for conditions in which sinus symptoms overlap with migraine and other craniofacial pain disorders. Full article

To explore the mechanism of action of CBS-derived H₂S in inducing cerebral vasodilation and activating BK_Ca channels. Sprague–Dawley (SD) rat middle cerebral arteries (MCA) were isolated from rat brains, and a pressure myography system was used to measure the effects of different concentrations of L-cysteine (L-Cys, 1 × 10^−5.5 to 1 × 10^−3.5 mol/L), a substrate for cystathionine-β-synthase (CBS)—a hydrogen sulfide (H₂S)-producing enzyme. Additionally, the effects of pretreatment with the CBS inhibitor amino-oxoacetate (AOAA, 1 mmol/L), the vascular endothelial growth factor receptor 2 inhibitor semaxanib (SU5416, 10 μmol/L), and the large-conductance calcium-activated potassium (BK_Ca) channel blocker iberiotoxin (IBTX, 100 nmol/L) were investigated to determine their impacts on CBS-derived H₂S-induced vasodilation. Acute digestion of rat vascular smooth muscle cells (VSMCs) was performed, and whole-cell patch-clamp techniques were used to measure current changes in neurons or astrocytes (ASTs), as well as acutely digested VSMCs, in the presence of L-Cys, AOAA (1 mmol/L), SU5416 (10 μmol/L), and IBTX (100 nmol/L). Additionally, neurons or ASTs were co-cultured with VSMCs to determine CBS-derived H₂S levels. Neurons or ASTs co-incubated with blood vessels and then treated with L-Cys produced H₂S, which exhibited a concentration-dependent dilatory effect on middle cerebral artery occlusion (MCA) pre-contracted with 100 nmol/L U46619 (p < 0.01). However, the addition of AOAA significantly attenuated this dilatory effect (p < 0.01). SU5416 and IBTX significantly inhibited cerebral vascular dilation (p < 0.01). H₂S produced by adding L-Cys after co-incubation of neurons or ASTs with VSMCs significantly increased BK_Ca channel current (p < 0.01). However, this effect was significantly attenuated after adding AOAA (p < 0.01). SU5416 and IBTX significantly inhibited the activation of BK_Ca channels (p < 0.01). Wild-type rat neurons or astrocytes (ASTs) were co-cultured with CSE(Cystathionine γ-lyase)-knockout vascular smooth muscle cells (VSMCs-CSE KO); the addition of L-Cys significantly increased hydrogen sulfide (H₂S) levels in the co-culture system (p < 0.01), while the addition of AOAA reduced H₂S production (p < 0.01). However, the addition of SU5416 had no statistical significance. Neurogenic H₂S, the H₂S produced by neurons and ASTs, could induce cerebral vasodilation in rats via VEGFR₂(Vascular Endothelial Growth Factor Receptor 2)-mediated activation of BK_Ca channels in the smooth muscle cells. Full article

Module- and pack-level mechanical design of lithium-ion batteries in electric vehicles is a primary driver of swelling-induced stack pressure and spatially varying ageing. Current practice remains largely empirical or data-driven and configuration-specific, limiting the ability to predict how design changes translate into local pressure heterogeneity and state-of-health (SOH) loss. This motivates a compact chemo-mechanical model that maps packaging boundary conditions to pressure, swelling, and SOH evolution with few interpretable parameters. This study introduces finite-element-ready constitutive laws that couple reversible and irreversible swelling to SOH and through-thickness pressure, covering three boundary cases reported in literature: constant pressure, thickness clamp after an initial preload, and flexible support. Parameters are identified from different published datasets, and the model is validated against independent constraint scenarios. Good quantitative agreement is shown with averaged RMSE of 1.16% for SOH and 0.16 [MPa] for pressure evolution. Variance-based sensitivity analysis shows SOH uncertainty dominated by the damage-law parameters of the proposed constitutive relationship, whereas pressure evolution is primarily controlled by irreversible swelling and the non-linear through-thickness stiffness, indicating calibration priorities for engineering design studies. The framework is intended for fast comparative analyses of individual cells under a controlled environment. Further extensions, including SOC-dependent mechanics, refined hysteresis, temperature, and C-rate variations require dedicated datasets and are left for future work. Full article

This study investigates the joint characteristics of a 60-layered copper foil stack using linear vibration ultrasonic welding for lithium-ion pouch cell applications. With increasing demand for high-capacity electric vehicle batteries, ensuring the reliability of multilayer electrode joints is essential. Experiments were conducted by varying vibrational amplitude, welding time, and clamping pressure. Weld quality was analyzed based on indentation profiles, joint strength, and failure modes. Results revealed that optimal welding energy (500–900 J) produced well-formed joints without surface cracks or tearing. Excessive welding energy (>900 J) led to material thinning and interfacial failure. The maximum T-peel peak load of 138.7 N was obtained at the 30th joining interface under 25 µm amplitude, 0.8 s welding time, and 1.5 bar clamping pressure. Interface-dependent optimum conditions were observed, reflecting thickness–direction variations in deformation and bonding within the 60-layer stack. Indentation length and depth correlated linearly with welding energy. Failure modes transitioned from no adhesion to tearing and button-pull types. The findings provide guidelines for optimizing welding parameters for high-quality multilayer foil joints in battery manufacturing. Full article

A demountable connection is necessary to enable quick and easy replacement of high-temperature superconducting (HTS) tape samples during cryogenic (77 K) testing, particularly when investigating their application in superconducting fault current limiters (SFCLs). Testing HTS tapes for application in SFCLs involves inducing their transition from the superconducting state to the resistive state, which can result in sample damage. The contact resistance of the HTS tape to the current lead depends on the area and on the uniform pressure. Stress distribution in screwed connections with two, four and six screws was analysed using a solid model to compare them and achieve the uniform contact essential for minimising contact resistance in cryogenic conditions. The analysis indicated a solution that provides the most uniform pressure distribution across the HTS tape surface. This solution was utilised in subsequent calculations of thermal shrinkage, and for the determination of the optimal disc spring stack configuration. It is imperative that the compensating disc springs maintain the requisite pressure of the copper block on the tape across the entire operational temperature range (room to cryogenic). Furthermore, the disc springs must provide adequate stroke to compensate for the thermal shrinkage of a copper block and an aluminium clamp. Full article

Bolted connections are critical in deep-sea engineering, yet classical theories (such as VDI 2230) implicitly assume atmospheric pressure conditions, neglecting the volume contraction of components due to hydrostatic pressure. This fundamental flaw hinders accurate prediction of preload retention—especially when bolts and clamped components exhibit differential compressibility (a common scenario in practical applications). To bridge this scientific gap, this paper establishes the first analytical model for bolt preload under pressure-induced volumetric contraction based on deformation coordination relations. The derived closed-form expressions explicitly quantify residual preload as a function of deep-sea ambient pressure, component bulk modulus, and geometric parameters. Model predictions closely match finite element calculations, showing that stainless steel bolts clamping aluminum alloys under 110 MPa pressure can experience up to a 40% preload reduction. This theoretical framework extends classical bolt connection mechanics to high-pressure environments, providing a scientific basis for optimizing deep-sea connection designs through material matching and dimensional control to effectively mitigate pressure-induced preload loss. Full article

As the core component in intelligent manufacturing systems, the precise control of the welding clamp’s electrode pressure plays a decisive role in ensuring the quality of spot welding. This paper proposes a novel pressure control strategy for robotic welding clamp based on partitioned adaptive RBF neural networks: (1) Deformation of the clamp body can lead to deviations in workpiece positioning. To address this issue, a deflection compensation method for robot welding clamp based on the PSO-RBF neural network is proposed. By leveraging pre-calibrated empirical data, the intrinsic mapping relationships are identified, and the derived deflection compensation value is integrated into the real-time position command of the robot end-effector. (2) During electrode motion, the system is subjected to external disturbances such as friction and gravitational forces. So, a sliding mode control strategy incorporating adaptive RBF disturbance compensation is proposed to achieve robust speed regulation. Furthermore, the electrode’s reference velocity is dynamically adjusted based on the welding force error and improved admittance control algorithm, enabling indirect regulation of the welding force to reach the desired set value. The results demonstrate that the proposed composite control strategy reduces electrode pressure overshoot to less than 5% and enhances steady-state control accuracy to ±1.5%. Full article

Titanium alloy TC4 countersunk head bolts (CHB) are widely used in spacecraft structures, but the research on CHB does not receive enough attention at present. There are still some more opportunities worthy of in-depth research, such as insufficient research on CHB of high-strength fasteners for aerospace applications, an insufficient combination of CHB simulation tests with real working conditions, and inspection and testing methods. In this study, through the combination of finite element simulation and experiments, the working conditions of the CHB connection structure bearing tensile load and CHB screwing were analyzed, and the requirements of the CHB connection structure and installation of CHB were optimized. Based on the single-bolt tensile simulation, the working conditions of multi-bolt connection structures under eccentric load and single-bolt composite laminate connection structures under tensile load were analyzed. Meanwhile, the structure of CHB was further optimized, and the simulation analysis model of the CHB tightening process was established. The research shows that the larger fixing bolt countersunk angle θ₁ and the smaller countersunk fillet radius r, the better the ultimate bearing capacity of the connection structure will be. When the countersunk bevel angle of pressure plate θ₂ was greater than or less than 100°, the clamping force–angle slope will decrease, while when θ₂ was smaller, it will have a greater influence on the slope. The coaxiality Φ had little influence on the slope around the allowable tolerance range (0.3 mm), but the influence on the slope becomes greater when it exceeds the tolerance range. The research results provide a reference and basis for the layout of CHB and the use of composite materials in aerospace connection structures. Full article

A novel hydraulically actuated uniform clamping flange connection mechanism is proposed to address the long-standing challenges in high-pressure natural gas flowmeter calibration, including cumbersome bolt-by-bolt assembly/disassembly, high leakage risk, and severe non-uniform gasket contact pressure associated with conventional multi-bolt flanges. Unlike traditional discrete bolt loading, the proposed mechanism generates a continuous and actively adjustable circumferential clamping force via an integrated hydraulic annular piston, ensuring excellent sealing uniformity and rapid installation within minutes. A high-fidelity transient finite element model of the hydraulic clamping flange assembly is established, incorporating the nonlinear compression/rebound behavior of flexible graphite–stainless steel spiral-wound gaskets and one-way fluid–structure interaction under water hammer loading. Parametric studies reveal that reducing the effective clamping area to below 80% of the original design significantly intensifies stress concentration and compromises sealing integrity, while clamping force below 80% or above 120% of the nominal value leads to leakage or component overstress, respectively. Under steady 10 MPa pressurization, the flange exhibits a maximum stress of 150.57 MPa, a minimum gasket contact stress exceeding 30 MPa, and a rotation angle below 1°, demonstrating robust sealing performance. During a severe water hammer event induced by rapid valve closure, the peak flange stress remains acceptable at 140.41 MPa, while the minimum gasket contact stress stays above the critical sealing threshold (38.051 MPa). However, repeated water hammer cycles increase the risk of long-term gasket fatigue. This study introduces, for the first time, a hydraulic uniform-clamping flange solution that dramatically improves sealing reliability, installation efficiency, and operational safety in high-pressure flowmeter calibration and similar temporary high-integrity piping connections, providing crucial technical guidance for field applications. Full article

In response to ground pressure problems such as an abnormal increase in working face support resistance and severe roadway floor heave induced by the lateral composite structure of the multi-layer thick and hard roof in the 11,223 working face of Xiaojihan Coal Mine, based on the triangle area slip theory, this study reveals that the lateral triangle area forms a composite structure of “cantilever beam + masonry beam”. The stress transfer and unloading mechanism of the high- and low-position thick and hard rock stratum fracturing was clarified. A technical scheme is proposed and implemented to weaken the high- and low-position thick and hard rock strata through horizontal Long Directional Borehole synergistic fracturing and optimize stress transfer. The results show that (1) the lateral overlying rock forms a triangular slip area under the clamping of the cantilever and masonry beam structures. This composite structure is the main reason for the increase in the support resistance at the end of the working face and the stress concentration of the roadway surrounding rock. (2) The influence law that the load of the triangular slip area is mainly influenced by the length of the broken block, and the breaking angle was clarified. The distribution characteristics of the load in the lateral triangle area under the fracturing of thick and hard rock strata at different horizons are mastered. When the length of the key block is reduced by 40%, the supporting force F₁ of the rock mass below the broken block on it is reduced by 62.5%, and the supporting force F₂ and the frictional force F₃ of the end part on the broken area of the triangle area are reduced by 34.6%. (3) The fracturing of high- and low-position thick and hard rock strata can collaboratively weaken the stress accumulation at high and low positions. Fracturing the low-position thick and hard rock strata can cut off the low-position “cantilever beam” structure, and fracturing the high-position thick and hard rock strata at the same time can transfer the load of the “masonry beam”. Through simulation, it is seen that the stress peaks at the end of the working face and the roadway surrounding rock during synergistic fracturing are, respectively, reduced by 12.2% and 28.9%. (4) An industrial test of directional drilling hydraulic fracturing of lateral thick and hard rock strata is carried out, achieving the regulation effect that the average value of the support resistance at the end of the cycle is reduced from 27.2 MPa to 22.7 MPa, and the floor heave amount of the reused roadway is reduced by 62.3%. The research results can provide a reference for the advanced treatment of the strong ground pressure area of the multi-layer thick and hard roof. Full article

This article presents an analytical and simulation analysis of the stability of an innovative handling trolley. The analysis demonstrated that the loaded trolley (100 kg load) requires a critical tipping force F_crit of 502.24 N and a work W of 279.05 J. A comparative analysis confirmed a 128% higher force stability for the proposed solution compared to a standard model F_crit = 220 N. Following the structural design, a prototype was created and tested directly at the workplace for which it was designed; in addition to load tests, which it passed without issue, it was necessary to verify its stability. This step was approached from both a theoretical and practical standpoint. Given the need for special clamping of the transported material, a test was first performed on the empty handling trolley, and subsequently, the trolley was verified with the material clamped. This procedure was applied to the theoretical mathematical analytical solution, the simulation, and the practical test. This process required full consideration, given the manner of clamping, the robust and heavy nature of the transported material, and its operation by a single operator. In the practical test, pressure was applied to the trolley, both without load and with load, which verified and confirmed its stability in both longitudinal and transverse directions. The conclusions define that the trolley’s structure was even more stable after adding the load (handling material). A prototype was created and tested directly at the workplace. Practical stability tests were conducted by applying lateral pressure to both empty and loaded configurations, confirming stability in longitudinal and transverse directions. Formal tilt-table testing according to EN 1757 and ISO 22915 standards is planned for final certification. Full article