Institute Of Mechanics,Chinese Academy of Sciences
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LDG全干法急冷换热器沉积灰反应活性研究
No full text急冷换热器是转炉一次除尘煤气全干法显热回收技术的重要装置之一，但实际应用过程中转炉煤气自身“多尘性”通常会导致换热管道出现严重积灰、堵塞现象。文章以转炉煤气全干法显热回收系统中急冷换热器表面沉积灰作为研究对象，通过表征实验详细研究了沉积灰反应活性对急冷换热器积灰问题的影响机制。实验结果表明沉积灰中大量Fe2+和Fe3+具有较强的氧化还原特性，在转炉冶炼过程中能够与CO和O2不断发生循环反应，加剧急冷换热器表面沉积灰，导致换热通道堵塞，影响系统连续稳定运行。采用必要的清灰手段是确保转炉煤气全显热回收系统长期运行的关键
非晶态固体冲击波响应的介尺度模拟
No full text非晶态固体不存在位错运动等传统晶体塑性机制,而是以原子团簇在介尺度的“剪切转变”诱导塑性变形.由于时空尺度限制,研究剪切转变在动态冲击作用下的动力学过程十分困难,因此非晶态固体冲击波响应的物理规律还不清楚.为此,本文基于剪切转变动力学建立了动态介尺度模型,结合有限元模拟,系统研究了非晶态固体的弹塑性冲击波响应随冲击速度和传播距离的演化规律.结果表明,随着冲击速度的增大,剪切转变激活逐渐增多且以塑性波模式逐渐追上弹性波前沿.剪切转变塑性波与加载波的相互作用导致Hugoniot弹性极限随传播距离呈现指数衰减,以及高速冲击时塑性前沿更快速地上升.通过改变剪切转变本征应变,本文还研究了塑性冲击前沿应变率随稳态冲击压缩Hugoniot态应力的非4次幂律关系,发现该幂律指数与非晶态固体到达Hugoniot弹性极限前内部剪切转变激活的非线性增殖密切相关
Stress-stress correlations in two-dimensional amorphous and crystalline solids
No full textStress-stress correlations in crystalline solids with long-range order can be straightforwardly derived using elasticity theory (ET). In contrast, the emergent elasticity of amorphous solids, rigid materials characterized by an underlying disordered structure, defies direct explanation within traditional theoretical frameworks. To address this challenge, tensor gauge theories have been recently proposed as a promising approach to describe the emergent elasticity of disordered solids and predict their stress-stress correlations. In this work, we revisit this problem in two-dimensional (2D) amorphous and crystalline solids by employing a canonical ET approach, supported by experimental and simulation data. We demonstrate that, with respect to static stress-stress correlations, the response of a 2D disordered solid is indistinguishable from that of a 2D isotropic crystalline solid, and it is well predicted by vanilla ET. Moreover, we show that the presence of pinch-point singularities in the stress response is not an exclusive feature of amorphous solids. Our results confirm previous observations about the universal character of static stress-stress correlations in crystalline and amorphous packings
Tilting of vortex rings in the oblique collision reduces the longitudinal quadrupole and octupole modes of aerodynamic sound
No full textThe aerodynamic sound generated by the oblique collision of two vortex rings is featured by the asymmetric emission associated with the octupole mode, which differs from the symmetric emission associated with the quadrupole mode observed in the coaxial collision of two vortex rings. This distinctive feature of aerodynamic sound is closely related to the tilting and reconnecting of the vortex rings. While previous studies have explored the effects of reconnecting on aerodynamic sound, this study specifically addresses the impact of vortex ring tilting. We propose a novel vortex sound formula to quantitatively assess the role of tilting in aerodynamic sound generation. The proposed formula relates the far-field sound pressure to equivalent circulations and vorticity centroids by referring to Truesdell's consistency conditions for vorticity moments. The variations of the equivalent circulations and vorticity centroids in the oblique collision of two vortex rings under different configurations are analysed based on the numerical solution of the Navier-Stokes equations in the source region. It is found that the tilting of vortex rings results in a rapid change of the equivalent circulation associated with the vorticity in the collision direction. However, the change caused by titling is almost out of phase with that caused by reconnecting and deforming. The vortex tilting significantly reduces the aerodynamic sound associated with the longitudinal quadrupole and octupole modes, which is opposite to the role of vortex reconnecting that was reported in the oblique collision of vortex rings
Establishment of a clinically relevant beagle model for periprosthetic joint infection with 3D-printed prostheses and multimodal evaluation
No full textObjective: Periprosthetic joint infection (PJI) poses significant challenges to arthroplasty outcomes, necessitating translational animal models for pathogenesis studies and therapeutic development. This study aimed to establish a standardized Beagle PJI model by integrating species-specific 3D-printed femoral prostheses with quantitative bacterial inoculation, while evaluating the dose-dependent effects of Staphylococcus aureus (S. aureus) on infection progression. Methods: Two titanium alloy prostheses were designed using CT-based anatomical data: BFP-C (canine-optimized) and BFP-H (human-derived). Prostheses underwent mechanical compression tests, finite element analysis (FEA) simulating postoperative and osseointegration phases, and in vivo validation in Beagles. The optimized BFP-C was selected for PJI model construction via hemi-hip arthroplasty (HHA), with intraoperative inoculation of S. aureus ranging from 250 to 108 colony-forming units (CFU). Longitudinal evaluation included radiography (X-ray/CT), mechanical pull-out tests, histopathology (H&E/Masson/Giemsa staining), bacterial cultures, and mobility assessments using open-field behavioural tracking. Results: BFP-C exhibited superior biomechanical compatibility, with 12.3-fold higher yield strength (6836 f 157 N vs. 553 f 49 N) and 97 % reduction in bone strain (0.71 % vs. 20.32 %) compared to BFP-H. All inoculated groups developed PJI with dose-dependent severity: ultra-high-dose (108 CFU) groups displayed severe osteolysis (pull-out strength: 24 f 8 N vs. 924 f 45 N in controls), biofilm formation, and mobility impairment (74 % reduction in distance travelled, 2003 f 276 cm vs. 7976 f 333 cm in controls), whereas low-dose (250 CFU) groups established PJI with milder manifestations, evidenced by sinus tract formation, 55.1 % reduction in pull-out strength (406 f 15 N vs. 924 f 45 N in controls), and concordant radiological/histopathological signs of infection. Imaging examinations revealed differential osteolytic patterns corresponding to bacterial loads. Combined wound evaluation and microbiological analyses confirmed consistent infection establishment across all replicates. Conclusion: This Beagle PJI model successfully recapitulates clinical infection dynamics, emphasizing the critical role of species-specific prosthesis design and standardized bacterial quantification. The integrated multimodal evaluation system (imaging, biomechanical, and behavioural analyses) demonstrated both the reliability of the model and its sensitivity in detecting infection progression. Its modular design supports customization for studying biofilm-resistant implants or antibiotic delivery systems. These findings not only provide a critical tool for mechanistic PJI research but also establish a theoretical foundation for clinical translation, with the quantitative multimodal framework directly informing diagnostic and therapeutic strategies. Translational potential: Beyond serving as a preclinical platform for anti-infective therapies, the model provides actionable insights into optimizing human prosthetic biomechanics, such as reducing stress shielding through FEA-informed design principles. The 3D printing workflow further demonstrates rapid prototyping capabilities for patient-specific orthopaedic implants
Biomechanical Effects of Partial Decortication on All-Suture and Conventional Suture Anchors in Different Bone Densities
No full textWhile biomechanical testing has shown a correlation between decortication and anchor failure load, the effects of partial decortication on the biomechanical properties of all-suture anchors remain unclear. We aimed to evaluate the biomechanical effects of partial decortication on all-suture anchors and conventional suture anchors in Sawbones of varying densities. Suture anchors were tested in nondecorticated, partially decorticated, and completely decorticated Sawbones. Two types of all-suture anchors and one type of conventional anchor were evaluated. Two types of biphasic polyurethane foam were used to mimic normal bone: 0.32 g/cm3 density (20 pounds per cubic foot, pcf 20) and osteoporotic bone: 0.16 g/cm3 density (10 pounds per cubicfoot, pcf 10). Cyclicloadingswere applied, and peakdisplacementwas recorded. After cyclic loading tests, surviving anchors were subjected to pull-to-failure tests. The number of cycles, peak displacement, ultimate failure loads, and failure modes were determined. First, peak displacement was significantly influenced by bone density and anchor type: normal bone models exhibited lower peak displacement than osteoporotic models, and conventional screw-type anchors consistently demonstrated reduced peak displacement compared to all-suture anchors. In contrast, the extent of bone decortication-whether non-decorticated, partially decorticated, or completely decorticated-showed no significant effect on peak displacement. Second, in osteoporotic bone models (10 pounds per cubic foot), no significant difference in failure load was observed between the partially and non-decorticated groups, but both exhibited significantly higher values than the completely decorticated group
Numerical Investigation of Drop Impact on Immiscible Liquid-Liquid Interfaces
No full textIn this paper, we numerically investigate the levitation behaviors of a drop impacting an immiscible liquid-liquid interface, disregarding the influence of gravitational acceleration. Through energy budget analysis, we elucidate that the phenomenological model proposed by Sanjay et al. (J. Fluid Mech., 2023, vol. 958, p A25) and Jha et al. (Soft Matter. 2020, vol. 16, pp 7270-7273) is partially applicable to drop impact on liquid-liquid interfaces. Specifically, the magnitude of energy transferred from the impacting drop to the liquid film remains unchanged despite a two-orders-of-magnitude variation in the density of the surrounding liquid. Additionally, the normalized maximum film deflection exhibits a significant two-stage growth characteristic with increasing liquid film thickness under conditions of relatively high liquid film viscosity or an interfacial tension coefficient ratio. When the liquid film thickness is relatively low, the energy transfer from the impacting drop to the liquid film is also insensitive to changes in the interfacial tension coefficient ratio
Optimizing the electronic structure of carbon-based NiFe nanoparticles <i>via</i> a vanadium mediated strategy for efficient oxygen reduction catalysts in Zn-air batteries
No full textTo improve the catalytic activity of oxygen reduction reaction (ORR) catalysts, optimizing their electronic structure for active sites to reduce electrochemical reaction energy barriers is an effective strategy. Herein, we fabricated vanadium (V)-doped NiFe alloy NPs embedded in an N-doped carbon matrix (V-NiFe@NC) as an electrocatalyst through a Joule heating-assisted MOF derived route. The resulting catalyst exhibits good ORR activity (E1/2 = 0.882 V) and stability, better than its undoped counterpart (NiFe@NC) and commercial Pt/C, confirming the effectiveness of V-doping in enhancing catalytic activity. Electrochemical tests disclose the enhanced intrinsic catalytic activity and kinetic process of V-NiFe@NC, benefiting from its optimized electronic configuration regulated by the incorporation of V atoms. Meanwhile, DFT calculations reveal that the outer N-carbon layer, serving as the primary active site, can be effectively activated by the V-doped NiFe substrate in V-NiFe@NC, thereby reducing the ORR energy barrier and boosting its catalytic activity. This electrocatalyst further demonstrates high peak power densities (178.8 mW cm-2), specific capacity and durability in alkaline Zn-air batteries, indicating its practicality in electrochemical energy conversion devices.</p
Manipulation of single-mode perturbation growth driven by co-directional rarefaction and shock waves
No full textRayleigh-Taylor (RT) stability occurs when a single-mode light/heavy interface is accelerated by rarefaction waves, exhibiting a sustained oscillation in perturbation amplitude. If the perturbation is accelerated again by a shock propagating in the same direction as the rarefaction waves, the interface evolution will shift from RT stability to Richtmyer-Meshkov (RM) instability. Depending upon the interface state when the shock arrives, the perturbation growth can be actively manipulated through controlling the magnitudes of vorticity deposited by rarefaction and shock waves. The present work first theoretically analyses the 12 different growth possibilities of a light/heavy interface accelerated by co-directional rarefaction and shock waves. A theoretical model is established by combining the RT growth rate with the RM growth rate, providing the conditions for the different possibilities of the perturbation growth. Based on the model, extensive experiments are designed and conducted in the specially designed rarefaction-shock tube. By precisely controlling the shock arrival time at the interface, the different growth possibilities, including promotion, reduction and freeze-out, are realised in experiments. This work verifies the feasibility of manipulating the light/heavy perturbation via co-directional rarefaction and shock waves, which sheds light on control of hydrodynamic instabilities in practical applications