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A Biologically Muscle-Inspired Polyurethane with Super-Tough, Thermal Reparable and Self-Healing Capabilities for Stretchable Electronics
No full textPolymeric elastomers play an increasingly important role in the development of stretchable electronics. A highly demanded elastic matrix is preferred to own not only excellent mechanical properties, but also additional features like high toughness and fast self-healing. Here, a polyurethane (DA-PU) is synthesized with donor and acceptor groups alternately distributed along the main chain to achieve both intra-chain and inter-chain donor-acceptor self-assembly, which endow the polyurethane with toughness, self-healing, and, more interestingly, thermal repair, like human muscle. In detail, DA-PU exhibits an amazing mechanical performance with elongation at break of 1900% and toughness of 175.9 MJ m(-3). Moreover, it shows remarkable anti-fatigue and anti-stress relaxation properties as manifested by cyclic tensile and stress relaxation tests, respectively. Even in case of large strain deformation or long-time stretch, it can almost completely restore to original length by thermal repair at 60 degrees C in 60 s. The self-healing speed of DA-PU is gradually enhanced with the increasing temperature, and can be 1.0-6.15 mu m min(-1) from 60 to 80 degrees C. At last, a stretchable and self-healable capacitive sensor is constructed and evaluated to prove that DA-PU matrix can ensure the stability of electronics even after critical deformation and cut off
Unprecedented tribological performance of binary Sb/Ag-doped MoS2 coatings fabricated with chemical vapor deposition
No full textThis study aims at assessing the tribological performance of novel self-lubricating chemical vapor-deposited MoS2 coatings binary-doped with antimony (Sb) and silver (Ag). The Sb/Ag-doped MoS2 composite coatings showed an excellent solid lubrication performance with low and constant coefficients of friction of about 0.1 for a sliding time of 6 h. Estimations of the underlying wear rates revealed a reduction of the resulting wear rate by two orders of magnitude for the binary-doped Sb/Ag-MoS2 composite coatings (2.43 +/- 0.27 x 10(-7) mm(3)/Nm versus 2.70 +/- 0.44 x 10(-5) mm(3)/Nm for un-doped MoS2 coating), which reflects an outstanding wear resistance
Probabilistic Latent Factor Model for Collaborative Filtering with Bayesian Inference
No full textLatent Factor Model (LFM) is one of the most successful methods for Collaborative filtering (CF) in the recommendation system, in which both users and items are projected into a joint latent factor space. Base on matrix factorization applied usually in pattern recognition, LFM models user-item interactions as inner products of factor vectors of user and item in that space and can be efficiently solved by least square methods with optimal estimation. However, such optimal estimation methods are prone to overfitting due to the extreme sparsity of user-item interactions. In this paper, we propose a Bayesian treatment for LFM, named Bayesian Latent Factor Model (BLFM). Based on observed user-item interactions, we build a probabilistic factor model in which the regularization is introduced via placing prior constraint on latent factors, and the likelihood function is established over observations and parameters. Then we draw samples of latent factors from the posterior distribution with Variational Inference (VI) to predict expected value. We further make an extension to BLFM, called BLFMBias, incorporating user-dependent and item-dependent biases into the model for enhancing performance. Extensive experiments on the movie rating dataset show the effectiveness of our proposed models by compared with several strong baselines
Non-Geometric Error Compensation for Long-Stroke Cartesian Robot With Semi-Analytical Beam Deformation and Gaussian Process Regression Model
No full textTill now, most calibration methods only compensate geometric error caused by inaccurate kinematic parameters, while the desired accuracy may still not be achieved when the robot is performing long-stroke, heavy-duty loading and unloading tasks. In this paper, a generalized semi-analytical beam deformation model is firstly proposed for the Cartesian robot to compensate the non-geometric error due to structural deformation under both distributed and concentrated loads. The adjustment factors are introduced in this model to deal with the over-constrained boundary conditions for both intermediate and side modules of the long-stroke Cartesian robot. This improves the fitness of the coming geometric error model, which assumes the beam to be rigid and straight. In addition, as the major error components which do not conform to the Gaussian distribution have been extracted in earlier steps, the Gaussian process regression model is imported to predict the residual error more accurately. In this way, comprehensive geometric and non-geometric error modeling and compensation procedures are formed for the multi-module, long-stroke Cartesian robot. Simulations and real-time experiments are conducted to validate the effectiveness of the proposed method
Construction of Zeolite-Loaded Fluorescent Supramolecular on-off Probes for Corrosion Detection Based on a Cation Exchange Mechanism
No full textMetal engineering structures are commonly covered and protected by coatings. However, the early local corrosion under the coatings and at defects is difficult to detect and discover. Visibility to the naked eye means that corrosion has already developed and expanded. Therefore, it is practical significant to detect the early corrosion of coated metal. Based on the formation of iron ions and anodic acidification in the local corrosion process, iron ions and proton responsive fluorescent rhodamine B acylhydrazone on-off probes are prepared by newly improved methods and denoted as RBA. RBA are loaded on the surface and in the lattice cage of zeolite (ZEO) to protect RBA from premature exposure to the corrosive environment and fluorescence quenching. In corrosive environments, the RBA loaded on the surface are released and complex with iron ions in the environment to activate fluorescence characteristics. Simultaneously, due to the cation exchange of ZEO, iron ions enter the lattice cage of ZEO and combine with RBA in the lattice cage to turn on fluorescence. When applied in epoxy coatings, the RBA/ZEO effectively indicate the occurrence of corrosion under the coatings and at defects, and accurately locate the corrosion site. Nano-scale ZEO (or RBA/ZEO) fill the micropores such as pinholes and defects of the coatings, and increase the difficulty of diffusion and penetration of corrosive media into the coatings. The application of RBA/ZEO functional filler not only do not weaken the main anti-corrosion performance of the coatings, but also significantly improve it
Design novel three-dimensional network nanostructure for lubricant infused on titanium alloys towards long-term anti-fouling
No full textTitanium alloys, recognized as a marine material with great potential, are currently facing serious biofouling problems, which greatly limits its application range. To improve the antifouling performance of titanium alloys, three unique surface of three-dimensional network, grass-like and linear nanostructures were obtained on titanium alloys via hydrothermal treatment in this work. Further, slippery liquid-infused porous surfaces (SLIPSs) were fabricated on titanium alloys via infusing PFPE lubricant into these nanostructures. Water contact angles and sliding angles of SLIPSs were measured to evaluate the effect of nanostructures on the stability of PFPE lubricant layer. Anti-fouling capability of SLIPSs were investigated by quantifying the cells of chlorella and phaeodactylum tricornutum (P. tricornutum)adhered to titanium alloys. The results shows that all the SLIPSs exhibited remarkable inhibition capacity for the settlement of chlorella and P. tricornutum. Among them, the SLIPS with three-dimensional network nanostructure displayed the longest-term anti-fouling performance, and its reduction rate of P. tricornutum and chlorella reaching 77.2 % and 84.5 % after being cultivated for 21 days, respectively, indicating that there existed a positive correlation between the stability of lubricant layer in the artificial seawater and the antifouling effect
Aqueous solution processed mesoporous silica-gated photo-perception neuromorphic transistor
No full textOur body is a multiple perception learning system. Bionic application of perception cognitive functions based on neuromorphic electronics would endow artificial intelligence new intension. In particular, electrolyte-gated transistors have been suggested for neuromorphic platform applications. Due to the fundamental limitations for ionic liquid and ionic gel-based electrolyte, it would be interesting to obtain solid-state electrolytes through a vacuum free system. Thus, in the present work, a simple aqueous solution-processed mesoporous silica coating-gated oxide photo-perception neuromorphic transistors have been proposed. The neuromorphic transistors exhibit good electrical performances. A resistor-loaded inverter is built, exhibiting typical inverter operation at low working voltage. 'Selective potentiation and depression' behaviors have been mimicked on the neuromorphic transistor. In addition, the proposed neuromorphic transistor shows optical and electrical synergic response behaviors. Neurological behavior of conditioned taste aversion learning has been mimicked. Thus, the single photo-perception neuromorphic transistor could integrate the functions of perception and neuromorphic algorithm. The proposed photo-perception neuromorphic transistors could have potentials in artificial perception learning systems
激光冲击强化对纳秒激光辐照铝合金诱致污染物产生规律的影响
No full text为了降低铝合金因激光辐照而产生颗粒污染物的几率,研究了激光冲击强化对纳秒激光辐照5052铝合金诱致污染物产生规律的影响。首先采用不同功率密度的纳秒激光对5052铝合金试样进行冲击强化,而后采用纳秒激光对激光冲击强化后的5052铝合金试样进行辐照-洁净度测试,最后对比分析激光冲击强化前后5052铝合金试样表面硬度、形貌、粗糙度及因激光辐照诱致污染物产生规律的变化。研究结果表明:激光冲击强化在提高5052铝合金表面强度的同时,对抑制低通量激光辐照(不高于0.65 J/cm~2)导致的污染物产生同样是有效的;对于粗糙度Ra为1.6的5052铝合金表面,经聚焦光斑直径为2.2 mm的高斯脉冲激光(光斑搭接率为50%,波长为532 nm,脉冲宽度为14 ns,功率密度为0.75～1.88 GW/cm~2)冲击强化后,低通量激光辐照阶段,激光诱致污染物(粒径为0.3～0.5μm)数量降低25%～50%。研究结果为5052铝合金因激光辐照,尤其是低通量激光辐照而产生污染物的控制提供了一种新的方法
海水抽水蓄能机组过流部件表面电弧喷涂涂层性能研究
No full text采用电弧喷涂技术制备了Al、75Zn25Al及Ni Cr涂层,通过基本性能测试、微观形貌表征及耐中性盐雾试验,研究了三种涂层在海水抽水蓄能机组过流部件中的腐蚀防护性能。研究结果表明,75Zn25Al涂层与基体结合力偏低,耐腐蚀性能较差,Al及Ni Cr涂层与基体结合力较高,具有极好的耐腐蚀性能,且Ni Cr涂层具有较高的耐磨损及冲刷性能。Ni Cr涂层可推荐应用于活动导叶中、下轴颈以及顶盖、底环过流面等部件的腐蚀防护,Al涂层可推荐应用于尾水管、蜗壳等部件的腐蚀防护