Search Results (352)

Reliable operation of adjustable ballast systems is essential for full-ocean-depth manned submersibles, but existing studies mostly focus on component-level performance optimization, leaving the multi-valve coupled instability mechanism under ultra-high pressure insufficiently understood. This paper investigates an uncontrolled water injection failure in the adjustable ballast system of the “Fendouzhe” submersible via fault tree analysis, high-pressure physical tests and AMESim dynamic simulations. Results show that the initial fit clearance of the downstream flow valve is the dominant prerequisite for instability, and a fluid–structure interaction positive feedback loop between the series valve assembly drives the flow surge fault. Removing the series flow valve fundamentally interrupts the coupling feedback loop. Full-range 0–115 MPa bench tests and follow-up sea trials confirm that the modified system eliminates the observed flow surge within the tested pressure range and operating conditions. This work provides a practical diagnostic framework and engineering reference for reliability design of high-pressure seawater hydraulic systems. Full article

Hydrogen, as a clean and renewable energy carrier, offers a promising solution to the global energy challenge, yet its safe and efficient storage remains a critical bottleneck. Metal–organic frameworks (MOFs), with their ultrahigh surface area, tunable porosity, and excellent stability, have emerged as leading candidates for physical hydrogen storage. This review systematically surveys recent progress in MOF-based hydrogen storage, organized by metal center type and examines the distinct adsorption mechanisms that govern hydrogen uptake. The regulatory effects of critical parameters including metal ion selection, pore architecture, and ligand functionalization on hydrogen storage capacity are analyzed in detail. Beyond material-level discussion, this review discusses the potential of MOFs for cryo-compressed hydrogen storage conditions. Key challenges facing practical deployment, including synthesis scalability, structural stability under cryogenic high-pressure cycling, and the knowledge gap in multi-cycle temperature-swing stability, are critically assessed. The roles of computational simulations and machine learning in accelerating MOF discovery and high-throughput screening are also reviewed. Finally, an application-oriented outlook is presented, mapping MOF performance to three specific industrial scenarios with reference to relevant economic analyses, thereby bridging fundamental materials chemistry with practical engineering requirements. Full article

This study evaluated the effect of chitosan with a high degree of deacetylation (75–85%) and three different molecular weights—low (50–190 kDa), medium (190–310 kDa), and high (310–375 kDa)—on the coating of vesicular systems. Chitosan solutions were characterized in acidulated aqueous medium by determining changes in pH, electrical conductivity, zeta potential, surface tension, viscosity, transmittance, particle size, and polydispersity index (PDI) with respect to polymer concentration. Subsequently, nanoliposomes were developed using an ethanol injection method assisted by ultra-high-pressure homogenization (UHPH) prior to coating. The characterization of the vesicular systems involved particle size analysis, polydispersity index (PDI), and zeta potential, which were evaluated at zero time and at the fourth week prior to storage at 4 °C and 40 °C. The physicochemical characterization of chitosan solutions displayed an inflection point at 1 × 10⁻³ M, which was taken as the coating concentration. In general, non-coated liposomes ranged between 150 and 200 nm, with low polydispersity (<0.3) and negative zeta potentials around ~−43 mV. Chitosan coating significantly increased particle size and PDI, while decreasing zeta potential values, but within the same negative value range, suggesting a slight interfacial coating effect. Finally, the systems subjected to UHPH and coated with high- and medium-molecular-weight chitosan showed interesting stabilization against storage conditions in the thermal stress tests. Full article

Polycrystalline diamond (PCD) has broad application prospects in semiconductors, optical windows and other advanced fields. Nevertheless, its ultrahigh hardness and chemical inertness pose significant challenges for achieving high-quality surface planarization. Although conventional mechanical lapping is widely adopted, it still suffers from poor surface quality and a lack of theoretical guidance for process parameter selection. This study presents a systematic experimental and simulation investigation on both rough and fine lapping of PCD, focusing on tool selection and process optimization. In the rough lapping stage, three types of fixed diamond abrasive discs with resin, bronze, and vitrified bonds were compared. The soft and tough resin-bonded disc yields the best performance, reducing surface roughness Ra from 420 nm to 106 nm. In the fine lapping stage, three metallic discs—Cu, Fe, and WC-Co—were evaluated. The high-stiffness WC-Co disc achieves the best results, with an Ra of 11.2 nm under conditions of 0.45 MPa and 600 r/min. Molecular dynamics (MD) simulations further reveal that increasing lapping pressure significantly enhances the material removal rate but concurrently aggravates subsurface damage (SSD), while the effect of speed is considerably smaller. Therefore, pressure emerges as the key parameter that requires balanced optimization in the fine lapping process. Full article

Located in the northeastern Tibetan Plateau, the Qaidam Basin hosts abundant strategic lithium (Li) and boron (B) salt lake resources crucial for national resource security. Existing studies focus on individual lakes, lacking systematic Li-B geochemical and source–transport–sink research across the geothermal–river–lake system. Based on 40 water samples from 16 lakes and multi-isotope and hydrochemical data, this study explores Li-B spatial distribution, isotopic evolution and enrichment rules. The results reveal prominent spatial heterogeneity of Li and B distributions. The contents of riverine Li and B are higher than the global average level, and terminal salt lakes show the highest enrichment degree. Specifically, southern lakes are Li-dominant, while northern lakes are B-dominant, with both reaching industrial exploitation grades. Significant Li and B isotopic fractionation occurs throughout the hydrological system, with geothermal fluids presenting depleted isotopic compositions and lake waters showing enriched features. H-O isotopic evidence and Gibbs diagram analysis indicate that surface waters in the basin are primarily recharged by atmospheric precipitation, and their hydrochemical compositions are jointly controlled by rock weathering and strong evaporative concentration, accompanied by distinct north–south hydrogeological zonation differences. Source analysis demonstrates that Li is mainly derived from high-temperature water–rock interactions of Li-rich volcanic and granitic rocks in the southern East Kunlun Mountains, whereas B originates from ultrahigh-pressure B-rich metamorphic rocks along the northern North Qaidam margin. The migration and accumulation sequence of Li and B follows the pathway: geothermal fluid emission → fluvial transportation → terminal lake enrichment. Evaporation and mineral precipitation are the dominant factors controlling elemental enrichment and isotopic fractionation. This basin-wide study supplements salt lake critical mineral metallogenic theories and guides efficient Li-B exploration and sustainable development. Full article

In-Mold Electronics (IMEs) present a highly promising monolithic integration strategy for manufacturing miniaturized 3D MEMS optical tweezers, offering exceptional environmental adaptability and structural compactness. However, the precision of such optical systems is heavily constrained by the injection molding process. During the molding phase, high-pressure melt scouring and severe thermo-mechanical coupling frequently induce geometric misalignment, manifesting as node displacement, localized warpage, and residual stress accumulation in the embedded circuits. This displacement critically alters the cross-sectional area of conductive traces, leading to resistance fluctuations that can destabilize the driving current. According to American Wire Gauge (AWG) standards, ensuring the geometric fidelity of this sensor-CPU interconnect pathway is fundamental to maintaining signal integrity. To address these manufacturing bottlenecks, this study systematically investigates the process stability of IME circuits Cyclic Olefin Copolymer (COC) is strategically selected as the substrate material over Polycarbonate (PC) and Liquid Silicone Rubber (LSR) due to its ultra-high light transmittance, extremely low water absorption, and superior thermomechanical stability. Based on finite element simulation, a data-driven intelligent optimization framework is developed. Latin Hypercube Sampling (LHS) is first utilized to efficiently sample the multi-dimensional process space, comprising melt temperature, packing pressure, and packing time. To handle the non-stationary nature of process feedback signals, wavelet analysis is introduced to decouple high-frequency noise, extracting Wavelet Energy Entropy (WEE) as a highly robust dynamic metric for process stability. Subsequently, a hybrid NSGA-II-MOPSO multi-objective algorithm is deployed to cooperatively optimize the injection parameters. The simulation-based optimization results demonstrate a substantial enhancement in manufacturing precision. Under the optimal parameter configuration, the average node displacement of the embedded circuits decreases significantly from 0.034 mm to 0.014 mm, achieving a 58.82% reduction. Simultaneously, volumetric shrinkage drops from 5.755% to 4.832% (a 16.04% reduction), while residual stress is maintained well within the structural safety threshold of optical-grade polymers. By clarifying the deformation control mechanism during the manufacturing phase, this study provides a highly reliable, data-driven methodological framework for the precision mass production of micro-nano optical systems. Full article

Ferrofluid sealing is an important non-contact sealing technology for ultra-high vacuum (UHV) equipment, but its reliability is affected by more than pressure-bearing capacity alone. This review shows that carrier-liquid evaporation, material outgassing, thermal degradation, magnetic-field distortion, and liquid-ring instability are the main factors limiting UHV ferrofluid seals. Multiphysics simulation and parametric optimization remain the most mature tools for analyzing magnetic-field distribution, pressure resistance, temperature rise, and structural deformation. Data-driven condition identification improves failure monitoring, whereas physics-informed neural networks, topology optimization, and multi-objective optimization are still emerging methods for low-sample prediction and collaborative design. Future studies should focus on low-vapor-pressure ferrofluids, bake-out compatibility, thermal management, lifetime prediction, and integrated model–data design frameworks. Full article

Facing the stringent demands of ultra-high pressure fuel injection systems on atomization quality and mixing efficiency, non-circular nozzle geometries have shown significant potential. Biodiesel, as a renewable alternative fuel, suffers from poor atomization due to its high viscosity, low volatility, and large surface tension, posing greater challenges for injector design. Among non-circular designs, the equilateral triangular orifice offers distinct advantages in promoting atomization of high-viscosity fuels and inducing jet axis-switching. This study demonstrates that such triangular nozzles under ultra-high pressure conditions exhibit intense turbulent vorticity at the outlet and distinctive cavitation development, which significantly affect the primary breakup of biodiesel. During spray development, a pronounced axis-switching behavior is observed, characterized by alternating spray cone angles between the major and minor axes. This phenomenon intensifies with higher injection pressure but is mitigated by increased ambient backpressure. The comparative analysis quantitatively establishes these macro–micro coupling characteristics over ultra-high injection pressures of 160–200 MPa, using fixed orifice lengths of 1.5 mm across exit cross-sectional areas ranging from 24,942 to 29,272 μm². The axis-switching process is accompanied by vigorous air entrainment, which significantly enlarges the spray projected area, accelerates liquid breakup, and shortens penetration distance, collectively enhancing the mixing rate and uniformity of biodiesel with air. This work systematically investigates the atomization characteristics and axis-switching behavior of equilateral triangular orifices with varying side lengths when injecting biodiesel under ultra-high pressure conditions, providing an effective technical pathway for the active control of spray morphology and atomization enhancement of biodiesel. Full article

(1) Background: As one of the world’s four major nuts, walnuts are rich in nutritional value; however, concerns regarding their allergenicity are becoming increasingly prominent. (2) Scope and Approach: This article provides a systematic review of the nutritional value and allergenicity of walnuts, the composition of major allergenic proteins, and their detection techniques. A particular focus is placed on elucidating the mechanisms by which different processing methods—including heat treatment, ultra-high pressure, ultrasound, low-temperature plasma, enzymatic treatment, and polyphenol modification—affect the structure and allergenicity of walnut allergenic proteins. (3) Key Findings and Conclusions: Current evidence suggests that processing techniques can alter the secondary and tertiary structures of walnut proteins, change the accessibility of linear or conformational epitopes, and reduce their Immunoglobulin E/Immunoglobulin G (IgE/IgG) binding capacity under certain in vitro conditions. Among these, high-temperature and high-pressure treatment, enzymatic hydrolysis, polyphenol modification, and combined processing strategies demonstrate promising potential for reducing walnut protein immunoreactivity. However, structural modifications, reduced antibody-binding capacity, or increased digestibility should not be directly interpreted as definitive evidence of reduced clinical sensitization. This paper summarizes the current status of the development and application of hypoallergenic foods, analyzes the technical challenges and future development directions, and aims to provide a theoretical basis and technical reference for the development of allergenicity-reduced walnut products. Full article

After long-term waterflooding in offshore oilfields, the remaining oil becomes highly dispersed and discontinuous. To address the limitations of classical waterflooding theory in describing the effects of microscopic oil occurrence and stress differences on oil-phase flow, this study investigated oil–water two-phase flow during heavy-oil waterflooding using core samples from the Bohai Oilfield. The evolution of the oil-phase starting pressure gradient at different water-cut stages was measured through core two-phase steady-state displacement experiments. By combining in situ core CT scanning with pore-scale phase-field simulations, the multi-form start-up mechanisms and microscopic causes of the oil phase were clarified. The fractal characteristics of the reservoir pore structure were further incorporated to establish a calculation method for the multi-form start-up resistance of the oil phase. The results show that, as the water cut increases, the starting pressure gradient of the oil phase exhibits a nonlinear increasing trend. At a water cut of 90%, the oil-phase starting pressure gradient is approximately 7–8 times that of the pure oil phase. Meanwhile, the oil phase gradually transforms from a continuous phase to a discontinuous phase, with a smaller pore radius and a larger surface area per unit volume. Owing to the Jamin effect, capillary force exerts a stronger influence on oil-phase flow, resulting in a significant increase in the starting pressure gradient during the ultra-high water-cut stage. These findings provide a pore-scale explanation for the increase in oil-phase starting pressure gradient during ultra-high water-cut waterflooding and offer a theoretical basis for the sustainable development of mature offshore oilfields. Full article

To investigate the early-stage flame propagation and pressure response of premixed H₂-O₂ combustion under ultra-high-pressure constant-volume conditions, a transient CFD model was developed for a large-volume confined chamber. The numerical framework combines a density-based solver, the Peng–Robinson real equation of state, large eddy simulation, and a reduced H₂-O₂ chemical kinetic mechanism. Simulations were conducted at initial pressures of 30 and 40 MPa, H₂/O₂ molar ratios of 8:1 and 12:1, and three-, four-, and five-point ignition configurations. The results show that increasing the initial pressure from 30 MPa to 40 MPa advances the pressure rise onset from approximately 1.65 ms to 1.28 ms and increases the maximum pressure rise rate from 18.6 MPa·ms⁻¹ to 27.4 MPa·ms⁻¹ under the H₂/O₂ = 8:1 and three-point ignition condition. Under the investigated fuel-rich conditions, increasing the H₂/O₂ molar ratio from 8:1 to 12:1 delays the pressure rise onset from approximately 1.28 ms to 1.46 ms and reduces the maximum pressure rise rate from 27.4 MPa·ms⁻¹ to 21.1 MPa·ms⁻¹. For the 30 MPa and H₂/O₂ = 8:1 cases, the four-point ignition case produces the largest pressure rise rate of approximately 23.5 MPa·ms⁻¹, whereas the five-point ignition case shows a lower pressure fluctuation amplitude of approximately 3.6 MPa. The present conclusions are based on CFD quantitative engineering predictions and should be further validated using quantitative experimental measurements. Full article

The excessive emission of greenhouse gases (CO₂, CH₄, SF₆, and CF₄.) is a primary driver of global climate change, making the development of efficient adsorption and separation technologies critically important for achieving carbon reduction goals. Metal–organic frameworks (MOFs) have attracted considerable attention in this field due to their crystalline porous structures, ultrahigh surface areas, and tunable pore architectures. However, pristine MOFs face significant bottlenecks including poor water stability, high bed pressure drops caused by their powdered form, and limited mass transfer, which severely hinder their industrial application. The integration of MOFs with functional materials such as carbon materials, polymers, metal oxides, and porous SiO₂ offers a synergistic strategy to overcome these limitations. Carbon materials provide hydrophobic barriers and mesoporous transport channels, polymers enhance processability and mechanical strength, metal oxides introduce basic sites for enhanced chemisorption, and MOF-on-MOF heterostructures enable atomic-level interfacial integration and pore synergy. This review systematically summarizes recent advances in MOF composites for the separation of CO₂, CH₄, and fluorinated greenhouse gases (SF₆, CF₄.), with an emphasis on design strategies, structure–performance relationships, and synergistic mechanisms across different composite types. Finally, the current challenges including scalable synthesis, long-term stability, and separation performance under realistic conditions are discussed, and future directions toward rational design and functional synergy for industrial carbon capture and fluorinated gas emission reduction are envisioned. Full article

After prolonged development, offshore edge- and bottom-water reservoirs have entered an ultra-high water-cut stage. Under long-time multilayer commingled production conditions, accurate dynamic quantification of layer-wise production remains technically challenging, and conventional production allocation approaches often lack the accuracy required for fine-scale reservoir management. To address these challenges, this study proposes a production allocation method that integrates static reservoir properties, dynamic production performance, and pressure-based correction. The resulting layer-wise allocation provides a quantitative basis for evaluating remaining oil utilization and delineating the distribution of remaining oil across individual layers. The method is formulated on the basis of a pseudo-steady-state productivity model that incorporates wellbore imperfection effects. The initial production rate of each layer is calculated by combining reservoir transmissibility with production pressure drawdown. To account for unequal pressure responses among layers under commingled production—resulting from pressure imbalance, limited edge- and bottom-water energy support, and interlayer interference—a correction factor is introduced to adjust the effective production contribution of low-pressure layers. Compared with the PLT test results, the average error of the conventional KH method was 16.7%, whereas the average error of the proposed method was reduced to 6.1%. The average error was reduced from 16.7% to 6.1%, corresponding to a 63.5% reduction in prediction error, indicating that the proposed approach can provide a more reliable estimation of layered production contribution. The proposed method enables continuous and dynamic production allocation for commingled wells without the need for frequent surveys, offering a practical tool for identifying multilayer production imbalance, evaluating remaining potential, and supporting development optimization in offshore oilfields. Full article

To address the critical challenge of excessive junction temperature caused by ultra-high heat flux densities (>100 W/cm²) in deep-sea LED Fish-Attracting Lamp (FAL) arrays, this study proposes a hybrid thermal management scheme integrating interfacial micro-texturing, chimney-effect convection, and heat pipe phase-change heat transfer, achieving the unification of passive high-efficiency heat dissipation and pressure-resistant sealing. The FAL housing structure is reconfigured using topology optimization to construct chimney-effect enhanced flow channels integrated with heat pipe bundle arrays, thereby establishing efficient heat conduction pathways from the Phenolic Resin Substrate (PRS) to the structural periphery. Micro-Element Texture (MET) arrays are fabricated at the PRS thermal interface to enhance interfacial thermal conductance. Based on multi-physics coupled numerical simulation, a parametric mapping model correlating geometric topology with thermal performance is established through response interface methodology, enabling the parametric optimization of micro-texture configurations. A thermal interface performance testing platform is constructed to validate the accuracy and reliability of the numerical model. Experimental results demonstrate that the integrated heat pipe technology effectively suppresses LED junction temperature rise; moreover, groove-type MET arrays oriented perpendicular to the gravity direction not only significantly increase the effective heat dissipation area but also optimize the dynamic characteristics of natural convection. This proposed solution reduces the maximum operating temperature of deep-sea FALs by 6.70% compared with conventional structures, providing an effective engineering solution for thermal structural design of high-power illumination systems. Full article

Energetic materials face dual challenges of enhancing detonation performance and replacing toxic lead-based formulations. Triazole-based energetic potassium salts typically struggle to achieve simultaneous high-density and excellent detonation properties. Herein, a novel gem-dinitro-functionalized 1,2,3-triazole energetic salt, tripotassium 4,5-bis(gem-dinitromethyl)-2H-1,2,3-triazolate (3K₃BNOT·4H₂O), was rationally designed and synthesized via a six-step mild route using diaminomaleonitrile as the starting material. The structure was fully characterized by IR, NMR, elemental analysis, and single-crystal X-ray diffraction (SC-XRD). 3K₃BNOT·4H₂O crystallizes in the triclinic system (space group P-1) and forms a three-dimensional K-O/K-N ionic coordination network, delivering an ultra-high anhydrous crystal density of 2.077 g·cm⁻³ at 193K. It exhibits a peak decomposition temperature of 183.8 °C (10 °C·min⁻¹), impact sensitivity of 5 J, and friction sensitivity of 60 N (standard BAM methods). The calculated detonation velocity and pressure reach 8836 m·s⁻¹ and 28.6 GPa, respectively, outperforming the classical explosive RDX. This work provides a structural analysis of triazole-based energetic potassium salt hydrates, and 3K₃BNOT·4H₂O shows structural potential as a high-energy energetic material; its initiating performance needs further experimental verification. Full article