期刊：
International Journal of Heat and Mass Transfer,2024年218 ISSN：0017-9310
通讯作者：
Zhou, XM
作者机构：
[Fu, Junjian; Tian, Qihua; Zhou, Xiangman; Zhou, Xing; Fu, Zichuan] China Three Gorges Univ, Coll Mech & Power Engn, Yichang 443002, Peoples R China.;[Zhou, Xing] China Three Gorges Univ, Hubei Key Lab Hydroelect Machinery Design & Mainte, Yichang 443002, Peoples R China.;[Bai, Xingwang] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.;[Zhang, Haiou] Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
通讯机构：
[Zhou, XM ] C;China Three Gorges Univ, Coll Mech & Power Engn, Yichang 443002, Peoples R China.
关键词：
WAAM;External deflection magnetic field;Heat and mass transfer;Numerical simulation;Overlapping flatness
摘要：
During the magnetic controlling wire arc additive manufacturing (WAAM) process, the external magnetic field directly influences the arc shape and the molten pool flow, which can further affect the morphology of the deposition layer and the overlapping flatness. This study introduced an external deflection magnetic field (EDM) with longitudinal and deposition direction components into the WAAM process. A numerical simulation model of the coupling of the arc and the molten pool was established on the basis of a weak coupling method. The numerical simulation model was utilized to investigate the effect of the EDM field on the heat and mass transfer behaviors in the WAAM overlapping deposition process. The results showed that the EDM field generated an additional electromagnetic force in the welding arc and molten pool with circumferential and single-side lateral components. The additional electromagnetic force drove the arc plasma to the rear of the molten pool and the side of the solidified weld bead simultaneously, which resulted in more heat and electromagnetic force concentrated on the gap of the overlapping beads. An asymmetric circumferential rotating vortex appeared in the molten pool, which drove the melted metal to fill the gap of the overlapping beads and improved the overlapping flatness.
关键词：
Al2O3–ZrO2;Crack propagation;Cracks;Laser powder bed fusion;Microstructure
摘要：
Abstract The cracks in Al2O3–ZrO2 eutectic ceramics produced by laser powder bed fusion (LPBF) have a significant impact on their practical applications in various industries. In order to understand the factors influencing crack formation, a systematic study of the characterization and propagation of cracks in single‐track, multi‐track, and bulk samples by varying the process parameters has been carried out in this research. The results showed that parallel cracks can be healed by reducing the scanning spacing and scanning length. Additionally, it was found that using a modest scanning speed and a shorter length can minimize the accumulation of thermal stress, resulting in the suppress crack formation. Based on this conclusion, a crack‐free Al2O3–ZrO2 eutectic ceramic sample was finally obtained under the optimized parameters with the power of 100 W, the scanning speed of 100 mm/s, the hatch spacing of 100 μm, the scanning length of 3 mm, and the layer thickness of 50 μm. Additionally, three typical microstructures, including eutectic, cellular, and dendritic structures, were identified in the LPBF‐fabricated Al2O3–ZrO2 samples. The cellular microstructure showed improved crack inhibition capability due to the deflection and pinning effects. Cracks expand more easily in dendritic and eutectic microstructures, where anisotropy is more prominent.
摘要：
The cutting vibration generated by cutting forces is critical to the accuracy and efficiency of face-hobbed hypoid gears. However, few relevant works are currently on cutting dynamics modeling for the face-hobbing process due to its complex spatial relationships. This study developed an efficient cutting dynamics model considering comprehensive characteristics of the non-generated face-hobbed hypoid gear machining process. A concise and efficient analytical solution to cutting dynamics modeling for face-hobbing of hypoid gears is obtained by using a vectorization method to characterize chip regenerating mechanisms. The machine tool vibration caused by cutting forces is predicted and validated according to an industrial case study. The proposed cutting dynamic model is 36.11% more efficient than the semi-analytical dynamic model derived from other cutting force prediction methods, and its accuracy is also improved with an error of less than 15%. Furthermore, the proposed vectorization solution to face-hobbing cutting dynamics modeling will be a practicable and effective method for analyzing the chatter in the machining of complex surfaces.
摘要：
The long-lived fission products (LLFPs) are one of the major impediments to the development of nuclear energy due to their longevity and toxicity. The fast neutron reactor, with its high neutron flux and excessed neutron, is a strong candidate for transmuting LLFPs. In this investigation, 79Se, 99Tc and 129I were selected as the representative nuclide of LLFPs, and then neutron moderators were loaded into the LLFPs assembly with LLFPs to evaluate the effect of different loading approaches on transmutation efficiency by the transmutation performance of LLFPs. The results show that the optimal loading strategy of moderator could increase the TR and SR with 2.35 (1.01) and 284.80 (151.11), 0.36 (0.28) and 8.06 (7.88), 1.69 (0.69) and 11.45 (7.80), respectively. It is suggested that it can transmute an additional 4500 g, 1000 g and 6600 g of these three LLFPs per year.
通讯机构：
[Feng, K ] H;Hunan Univ, State Key Lab Adv Design & Mfg Vehicle Body, Changsha 410082, Peoples R China.
关键词：
gas foil bearing;shape memory alloy;THD analysis;thermal energy transport;thermoelastohydrodynamic lubrication
摘要：
Shape memory alloy (SMA)-gas foil bearings (SMA-GFBs) are novel gas bearings comprising top foil, SMA springs, and housing. The radial clearance, stiffness, and damping coefficients of SMA-GFBs can be regulated by the bearing temperature which is determined by the electric heating of SMA springs and the cooling flow. A 3D thermohydrodynamic model (THD) considering the conduction and convection of the top foil, bearing housing, and hollow rotor, and the heat energy of heated SMA springs is presented to simulate the temperature distribution of SMA-GFBs at different rotational speeds, heating powers, and cooling flows. Centrifugal growth of the rotor and thermal expansions of the rotor, SMA springs, and bearing housing are also considered. A test rig is built to measure the bearing temperature and to validate the effectiveness of the theoretical model and circumferential cooling mode. Parametric studies are conducted with different speeds, heating powers, and cooling flows. The heat transfer ratios of the rotor and substructure are also compared. Compared to the temperature differences of the bearing temperature in the circumferential or axial directions, the effects of rotational speed and cooling flow on the bearing temperature are more apparent. The phase transition process of SMA spring can be controlled by adjusting the rotor speed and the cooling flow reasonably, and then the temperature characteristics of SMA-GFB can be changed. The temperature depending on the compressed gas film and heated SMA springs and cooling flow can be adjusted to confirm the feasibility of actively altering the performance of the bearing-rotor system.
作者机构：
[Li, ZY; Li, Zhenye; Huang, Chenhui; Li, Yuehao; Zhang, Meng; Ding, Xu] Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Ding, Yu-Feng] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Zhu, Chunguang] Sichuan Univ Sci & Engn, Sch Mat Sci & Engn, Zigong 643002, Sichuan, Peoples R China.
通讯机构：
[Li, ZY ] U;Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.
关键词：
cathode interface layer;non-covalent interaction;organic solar cells;power conversion efficiency;vermiculite
摘要：
Interface modification plays an important role in improving the power conversion efficiency (PCE) of organic solar cells (OSCs). However, the low non-covalent interaction between the cathode interface layer (CIL) and nonfullerene acceptor (NFA) directly affects the charge collection of OSCs. Here, the non-covalent interaction between the CIL and NFA is enhanced by introducing the 2D vermiculite (VML) in the poly(9,9-bis(3 '-(N,N-dimethyl)-Nethylammonium-propyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide (PFN-Br) interface layer to form an efficient electron transport channel. As a result, the electron extraction efficiency from the active layer to the CIL is increased, and the PCE of OSCs based on PBDB-T:ITIC is boosted from 10.87% to 12.89%. In addition, the strategy of CIL doping VML is proven to be universal in different CIL materials, for which the PCE is boosted from 10.21% to 11.57% for OSCs based on PDINN and from 9.82% to 11.27% for OSCs based on PNDIT-F3N. The results provide a viable option for designing efficient CIL for high-performance non-fullerene OSCs, which may promote the commercialization of OSCs. The non-covalent interaction between the cathode interface layer and nonfullerene acceptor is enhanced by introducing vermiculite in the PFN-Br interlayer. As a result, the power conversion efficiency of organic solar cells based on PBDB-T:ITIC is boosted from 10.87% to 12.89%. image
摘要：
The inevitable organic matters in radioactive wastewater and contaminated waters pose great challenge in uranium recycling by traditional techniques. Here, a self-driven solar coupling system (SSCS), which was assembled by a TiO(2) @MXene/CF cathode and a monolithic photoanode, was proposed for synergistically recycling uranium and degrading organics from complex radioactive wastewater, combining with electricity production. The TiO(2) @MXene/CF was prepared via a simple annealing process with in-situ derived TiO(2) nanoparticles decorated Ti(3)C(2) MXene coated on carbon felt (CF). Under sunlight illumination, the photoanode captured electrons of organics, and drove electrons to the TiO(2) @MXene/CF, which exhibited an exceptional UO(2)(2+) adsorption and reduction capacity because TiO(2) nanoparticles provided plenty of surface hydroxyl groups for UO(2)(2+) adsorption, and the unique two-dimensional MXene facilitated the charge transfer. The SSCS with TiO(2) @MXene/CF removed almost 100% UO(2)(2+) and organics with rate constants of ∼21 and ∼6.9 times those of the system with CF, accompanying with excellent power output (∼1000 μW·cm(-2)). The fixed uranium on TiO(2) @MXene/CF was effectively reduced into insoluble UO(2) (91.1%), and no obvious decay was observed after 15 repeated uses. This study proposes a multi-functional and easy-operated way for remediating radioactive wastewater and contaminated waters, and gives valuable insights in designing cathode materials for uranium reduction.
摘要：
Molecular dynamics (MD) simulation toward the irradiation cascade collision of GaN (10−10) by using different primary knock-on atom (PKA) energies was performed. Simulation results showed that point defects comprising vacancies and interstitials in pairs increased with increased PKA energy. The number of stable defects after cascade collision was linearly related to the PKA energy, which well agreed with the Norgett–Robinson–Torrens equation. Then, we investigated the effect of irradiation-induced point defects on the nanotribological properties and subsurface damage of the GaN (10−10) workpiece by MD simulation of nanoscratching. The irradiation-induced point defects induced a significant change in the wear morphology, as well as more slight wear and a lower coefficient of friction, compared with non-irradiated GaN. The irradiated GaN also exhibited fewer chips and smoother surfaces than the non-irradiated one after scratching. The number of deformed atoms of GaN increased with increased PKA energy, suggesting that irradiation can suppress the atomic/near-atomic scale deformation of GaN crystal under certain conditions. The presence of point defects can, to some extent, hinder the development of dislocations and differentiate the scratching-induced subsurface damage. This study provided atomic-scale insight into the effect of irradiation point defects on the nanotribological behavior of GaN.
通讯机构：
[Zeng, QY ; Yu, T] U;Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Hunan, Peoples R China.
关键词：
Uranium reduction;Uranyl-organic complex;Organic degradation;Electricity;Resourcization;Solar energy
摘要：
Co-existed organics bring great challenges for uranium recycling from water because of the formation of obstinate complexes with uranyl ions (UO22+), predominated species of uranium in water). Here, we proposed an effective strategy to simultaneously decompose organics and recycle uranium from complex radioactive waste-water, combined with electricity production, by a solar-driven wastewater resourcization system (SWRS), in which an electrodeposited polyaniline (PANI) decorated carbon fiber (CF-PANI) cathode was used for highly efficient UO22+ reduction based on the abundant -NH-groups and conductivity of PANI. Under sunlight illu-mination, a BiVO4 decorated WO3 nanoplate array (BVO/WNP) combined with a rear silicon cell (SC) was applied as the monolithic photoanode to generate oxidative holes and derived hydroxyl radicals for robust organic oxidation, and driven electrons to the CF-PANI cathode for uranium reduction and simultaneous elec-tricity generation at external circuit. Compared to CF, the optimized CF-PANI improved the rate constants (k) by 6 and 6.7 times for UO22+ and organic removal, respectively, and enhanced power output by 2 times (Pmax, 1.12 mW/cm2). Additionally, near 100 % removal ratios for both UO22+ and organics accompanying with Pmax around 1 mW/cm2 were achieved by SWRS when treating model complex wastewater under wide conditions or even under real sunlight illumination. The fixed uranium on the CF-PANI cathode was mainly reduced into U(IV) species (95.8 %) and the repeated tests demonstrated the excellent stability of SWRS (without obvious decay after reusing 15 times). This work provides new insights on the resourceful treatment of radioactive wastewater and contaminated waters.
作者机构：
[Li, ZY; Li, Zhenye; Zou, Chuankai; Yang, Kaihang; Kang, Xiaomin; She, Luobin] Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Li, ZY; Li, Zhenye; Chen, Lin; Tang, Jing] Hunan Dahe New Mat Co Ltd, Hengyang 421001, Peoples R China.
通讯机构：
[Li, ZY ] U;Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.;Hunan Dahe New Mat Co Ltd, Hengyang 421001, Peoples R China.
关键词：
all-polymer solar cells;crystallinity;nanoparticle dopant;phase separation;transition-metal phosphorus trichalcogenides
摘要：
All-polymer solar cells (all-PSCs) demonstrate splendid advantages of thermal and mechanical stability. Nevertheless, the rock-ribbed trade-off between the crystallinity and phase separation scale of donor/acceptor (D/A) hinder the power conversion efficiency (PCE) improvement of all-PSCs. Here, a novel two-dimensional transition-metal phosphorus trichalcogenides (TMPTCs) namely Cd0.85PS3Li0.3 is intelligently designed and synthesized, and firstly employed as a nanoparticle dopant for PBDB-T:N2200-based all-PSCs. The two-dimensional Cd0.85PS3Li0.3 possess enormous surface area that can serve as the nucleation center, inducing the crystallinity of D/A without influencing the original phase separation. Such feature significantly boosted the charge transport, PCE (from 7.18% to 8.79%) and stability of PBDB-T:N2200-based device. Moreover, the Cd0.85PS3Li0.3 nanoparticle dopant was proved to be universal in non-fullerene small molecule acceptor (NFSMA)-based organic solar cells (OSCs), for which the PCE was boosted from 15.05% to 17.27% for PM6:L8-BO-based OSCs and from 17.29% to 19.10% for D18:L8-BO-based OSCs. These observations exemplify the significance of two-dimensional TMPTCs nanoparticle dopant as a tool for breaking the rock-ribbed trade-off between the crystallinity and phase separation scale of D/A in OSCs, which may open up a special field for making two-dimensional TMPTCs work in a unprecedented way in OSCs. Cd0.85PS3Li0.3 was added to active layer to break the trade-off between the crystallinity and phase separation of donor/acceptor, thus boosting the charge transport and power conversion efficiency of heterosystematic organic solar cellsallinity of donor/acceptor (D/A) without influencing the original phase separation, increase the charge transport of the PBDB-T:N2200 device, thus effectively restraining the charge recombination of the device. As a result, the power conversion efficiency (PCE) was boosted from 7.18% to 8.79%, for organic solar cells (OSCs) based on PBDB-T:N2200, from 15.05% to 17.27% for OSCs based on PM6:L8-BO and from 17.29% to 19.10% for OSCs based on D18:L8-BO.image (c) 2024 WILEY-VCH GmbH
期刊：
Structural and Multidisciplinary Optimization,2024年67(4):1-19 ISSN：1615-147X
通讯作者：
Z. Zhang
作者机构：
[Q. Chen; Z. Zhang; Dean Hu; C. Jiang] Hunan Key Laboratory of Reliability Technology for Nuclear Equipment, College of Mechanical and Vehicle Engineering, Hunan University, Changsha, China;[Chunming Fu] College of Mechanical Engineering, University of South China, Hengyang, China
通讯机构：
[Z. Zhang] H;Hunan Key Laboratory of Reliability Technology for Nuclear Equipment, College of Mechanical and Vehicle Engineering, Hunan University, Changsha, China
摘要：
Practical engineering problems often involve stochastic uncertainty, which can cause substantial variations in the response of engineering products or even lead to failure. The coupling and propagation of uncertainty play a crucial role in this process. Hence, it is imperative to quantify, propagate and control stochastic uncertainty. Different from most traditional uncertainty propagation methods, the proposed method employs Gaussian splitting method to divide the input random variables into Gaussian mixture models. These GMMs have a limited number of components with very small variances. As a result, the input Gaussian components can be conveniently propagated to the response and remain Gaussian distributions after nonlinear uncertainty propagation, which is able to provide an effective method for high-precision nonlinear uncertainty propagation. Firstly, the probability density function of input random variable is reconstructed by Gaussian mixture models. Secondly, the K-value criterion is proposed for selecting split direction, taking into account both the nonlinearity and variance. The components of input random variables are then divided into a Gaussian mixture model with small variance along the direction determined by the K-value. Thirdly, the individual components of the Gaussian mixture model are propagated one by one to obtain the probability density function of the response. Finally, the convergence criterion based on Shannon entropy is developed to ensure the accuracy of uncertainty propagation. The efficacy of the method is verified using three numerical examples and two engineering examples.
期刊：
Colloids and Surfaces A: Physicochemical and Engineering Aspects,2024年680:132731 ISSN：0927-7757
通讯作者：
Qian, L;Kang, XM
作者机构：
[Yu, Miao] Sichuan Univ, Sch Mech Engn, Chengdu 610065, Peoples R China.;[Qian, Lu; Qian, L] South China Univ Technol, Sch Mat Sci & Engn, Guangzhou 510641, Peoples R China.;[Kang, Xiaomin] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Kang, XM ] U;[Qian, L ] S;South China Univ Technol, Sch Mat Sci & Engn, Guangzhou 510641, Peoples R China.;Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
关键词：
Ion -specific effects;PEG;Single -molecule force spectroscopy;Quartz crystal microbalance with dissipation;H -bonds;Polymer -water interactions
摘要：
Understanding the intricate interplay between ions and polymers holds key implications for a myriad of fields, from biomedicine to materials science. Here, we present a comprehensive investigation of ion-specific effects on the behavior of single polyethylene glycol (PEG) chains, a versatile polymer widely used in various applications. Employing single-molecule force spectroscopy (SMFS) and quartz crystal microbalance with dissipation (QCM-D) techniques, we systematically explore the impact of different monovalent cations on structural and hydration dynamics of PEG, Surprisingly, our results demonstrate a non-linear ion-specific influence on the hydration of PEG chains. The introduction of ions significantly affects the binding water content and the single-chain elastic behavior of PEG. Intriguingly, monovalent cations display an intriguing concave relationship between their size and the extent of water binding. Li+ and Na+, characterized by their smaller size and higher charge density, induce pronounced hydration, thus altering the overall structural properties of PEG chains. In contrast, larger cations like Rb+ and Cs+ facilitate chain extension, while concurrently promoting the formation of binding water. Our findings offer a fresh perspective on the role of ion size and charge density in governing polymer-water interactions. Moreover, through quantitative analysis utilizing QCM data, we verify the intricate influence of ions on PEG chains. Our research contributes to unraveling the complex interplay between ions and polymers, highlighting the importance of ion-specific effects in shaping polymer behavior. While shedding light on the potential of polymer materials with tailored properties, it also underscores the need for further investigations into the mechanisms underlying ion-specific effects and their broader implications.
作者机构：
[Gao, Kang; Yi, Junhao; Zhang, Yun] Hunan Univ Sci & Technol, Sch Mech Engn, Xiangtan 411201, Peoples R China.;[Dong, Fang] Cent South Univ, Light Alloy Res Inst, State Key Lab Precis Mfg Extreme Serv Performance, Changsha 410083, Peoples R China.;[Chen, Pinghu; Chen, PH] Univ South China, Coll Mech Engn, Key Lab Hunan Prov Equipment Safety Serv Technol E, Hengyang 421001, Peoples R China.
通讯机构：
[Chen, PH ] U;Univ South China, Coll Mech Engn, Key Lab Hunan Prov Equipment Safety Serv Technol E, Hengyang 421001, Peoples R China.
关键词：
titanium and titanium alloys;surface treatment;classification of titanium alloys
摘要：
Titanium alloys are acclaimed for their remarkable biocompatibility, high specific strength, excellent corrosion resistance, and stable performance in high and low temperatures. These characteristics render them invaluable in a multitude of sectors, including biomedicine, shipbuilding, aerospace, and daily life. According to the different phases, the alloys can be broadly categorized into alpha-titanium and beta-titanium, and these alloys demonstrate unique properties shaped by their respective phases. The hexagonal close-packed structure of alpha-titanium alloys is notably associated with superior high-temperature creep resistance but limited plasticity. Conversely, the body-centered cubic structure of beta-titanium alloys contributes to enhanced slip and greater plasticity. To optimize these alloys for specific industrial applications, alloy strengthening is often necessary to meet diverse environmental and operational demands. The impact of various processing techniques on the microstructure and metal characteristics of titanium alloys is reviewed and discussed in this research. This article systematically analyzes the effects of machining, shot peening, and surface heat treatment methods, including surface quenching, carburizing, and nitriding, on the structure and characteristics of titanium alloys. This research is arranged and categorized into three categories based on the methods of processing and treatment: general heat treatment, thermochemical treatment, and machining. The results of a large number of studies show that surface treatment can significantly improve the hardness and friction mechanical properties of titanium alloys. At present, a single treatment method is often insufficient. Therefore, composite treatment methods combining multiple treatment techniques are expected to be more widely used in the future. The authors provide an overview of titanium alloy modification methods in recent years with the aim of assisting and promoting further research in the very important and promising direction of multi-technology composite treatment.
通讯机构：
[Tang, DW ] U;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.
摘要：
Carbon/polymer-based flexible electrothermal films, as a Joule heating material with excellent electrothermal properties, good formability, and lightweight, are a very needed material in aircraft wing de-icing systems, flexible electric heating elements, and low-voltage wearable devices. In this study, a series of flexible electrically heated films were successfully prepared using polyimide (PI) as the film-forming substrate and graphene (GE) as the conductive filler. The effects of graphene content on the morphology, microstructure, and electrothermal properties, as well as the mechanical flexibility of the electrothermal films, were systematically investigated. The results showed that the GE/PI electrothermal films not only retained the good electrical conductivity of graphene but also had the excellent mechanical properties and high heat resistance of polyimide. The electric heating film with the addition of 8 wt. % GE can quickly reach 390 C-degrees at 24 V with uniform temperature distribution, and the mass loss at 500 C-degrees is only 0.98 wt. %. A wide range of applications exist in fields such as flexible electric heating elements.
摘要：
This study proposes a piecewise high-order differential interpolation method with rapid convergence to construct an ultrasmooth high-speed cam profile. The proposed method enables a solution to be realized to manipulate the dynamic performance of a cam profile with C3 continuity during the whole working process. The reconstruction characteristics of the cam profile by the high-order differential interpolation method are compared with the most commonly used linear profile interpolation strategy. Thus, the proposed piecewise high-order differential interpolation method is validated as a feasible and effective methodology to design and reconstruct an ultrasmooth cam profile.
