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The purpose of this paper is to develop non-leaching and eco-friendly antimicrobial waterborne polyacrylates with excellent antibacterial properties by grafting antibacterial vinyl monomer, glycidyl methacrylate (GMA) modified polyhexamethylene guanidine hydrochloride (PHMG).

PHMG of different molecular weights were modified by GMA to synthesize antibacterial vinyl monomer, GMA-modified PHMG (GPHMG). Different content and molecular weights of GPHMG were used to synthesize antimicrobial waterborne polyacrylates through emulsion polymerization.

The addition of GPHMG gained by modifying PHMG showed little influence on thermal stability of the films, but decreased the glass transition temperature(Tg). Meanwhile, the tensile strength decreased, while the breaking elongation increased. The antibacterial properties of the antibacterial films with different GPHMG contents were studied, when GPHMG content was around 0.9 Wt.%, antibacterial films showed excellent antibacterial activity (antibacterial rate >= 99.99 per cent). When weight content of GPHMG in the films remained constant, antibacterial property of films increased first and then decreased with the increase of molecular weight of GPHMG. The structural antibacterial polymer film had more perdurable antibacterial activity than the blended one.

The grafting efficiency of GPHMG to antimicrobial waterborne polyacrylates could be further improved.

Antimicrobial waterborne polyacrylates with excellent antibacterial properties can be used to antibacterial coating and adhesive.

The antibacterial properties of films with different molecular weight of GPHMG were studied, and the durability and stability of antibacterial properties between structural antimicrobial films and blended antimicrobial films were also investigated by ring-diffusion method.

The purpose of this paper is to analyze the stiffness reliability of harmonic drive (HD) considering contact pairs wear.

In terms of theoretical calculation, the contact pairs wear of HD are calculated based on Archard wear formula and the relative motion characteristics of contact pairs. According to the motion trajectory of flexspline teeth, the teeth backlash and the number of meshing teeth, the meshing stiffness and overall stiffness of HD are analyzed considering the wear and its randomness of contact pairs. Combined with Monte Carlo Simulation, the stiffness reliability evaluation method considering contact pairs wear is proposed, and the result of this method is verified by the stiffness reliability result deduced from the stiffness degradation measurement data.

Considering contact pairs wear, during operation, the teeth backlash increases, the number of meshing teeth decreases, the meshing stiffness decreases, ultimately leading to a gradual decrease in the overall stiffness of HD. When only one type of contact pair wear is considered, the influence of flexspline and circular spline contact pair wear on HD stiffness reliability is greater. Compared with the stiffness reliability evaluation results obtained from the stiffness degradation data in the literature, the mathematic expectation of stiffness degradation failure life distribution obtained from the proposed method is relatively bigger.

The stiffness reliability evaluation method of HD considering contact pairs wear is firstly proposed. The stiffness reliability evaluation result from theoretical calculation is verified by the stiffness reliability results deduced from HD stiffness degradation measurement.

The purpose of this paper is to analyze the time-dependent reliability of harmonic drive.

The transient finite element analysis (FEA) of harmonic drive is established to calculate the stress under different loads. Combined with the residual strength model and random variables, the time-dependent reliability model of harmonic drive is deduced by the stochastic perturbation method and Edgeworth series. Based on accelerated life tests, the degradation parameters are estimated by maximizing likelihood function. Under variable load, the key stress from transient FEA is transformed into probability density function by kernel density estimation, and the residual strength model is modified by adding adjustment factors to deal with strength degradation under different loads.

The critical position of stress concentration from transient FEA is consistent with the fatigue fracture position at the accelerated life test sample. Compared with the time-dependent reliability method with equivalent circular-shell static stress or empirical degradation parameters, the proposed method has the smallest prediction error of failure life. Under variable load, the state function should be expanded to second-order series for avoiding error items relevant to variance. The failure life expectation under random variable load is smaller than that under constant load.

The time-dependent reliability method of harmonic drive is firstly proposed under constant and variable load. The transient FEA of harmonic drive is established to calculate the stress for strength analysis. The accelerated life test of harmonic drive is conducted for degradation parameters estimation. The adjustment factor is added to the residual strength model for strength degradation under different loads.

China’s educational leaders have long debated the pluses and minuses of decentralization of control and resources of China’s vast educational enterprise. During various periods of post‐1949 China, the central authorities have devolved control to the provinces, key cities, and rural communes, only to recentralize later usually due to political reforms. In this chapter various stages of the educational reform movement begun in 1985 will be considered and we will focus on what motivated the reforms in the context of China’s unique political culture. Some specific features of educational decentralization will be examined such as finance, curriculum and management. We conclude that while the current leadership appears to be committed to decentralization, they remain conflicted over the need to maintain control while at the same time respond creatively to the needs of the new market economy.

Because of the compact structure, short flexspline (FS) harmonic drive (HD) is increasingly used. The stress calculation of FS is very important in design and optimization of HD system. This paper aims to study the stress calculation methods for short FS, based on mechanics analysis and finite element method (FEM).

A rapid stress calculation method, based on mechanics analysis, is proposed for the short FS of HD. To verify the stress calculation precision of short FS, a complete finite element model of HD is established. The results of stress and deformation of short FS in different lengths are solved by FEM.

Through the rapid calculation method, the analytical relationship between circumferential stress and length of cylinder was obtained. And the circumferential stress has proportional relation with the reciprocal of squared length. The FEM results verified that the rapid stress calculation method could obtain accurate results.

The rapid mechanics analysis method is practiced to evaluate the strength of FS at the design stage of HD. And the complete model of HD could contribute to improving the accuracy of FEM results.

The rapid calculation method is developed based on mechanics analysis method of cylinder and equivalent additional bending moment model, through which the analytical relationship between circumferential stress and length of cylinder was obtained. The complete three-dimensional finite element model of HD takes the stiffness of bearing into consideration, which can be used in the numerical simulation in the future work to improve the accuracy.

The purpose of this paper is to analyze the dependent competing failure reliability of harmonic drive (HD) with strength failure and degradation failure.

Based on life tests and stiffness degradation experiments, Wiener process is used to establish the accelerated performance degradation model of HD. Model parameter distribution is estimated by Bayesian inference and Markov Chain Monte Carlo (MCMC) and stiffness degradation failure samples are obtained by a three-step sampling method. Combined with strength failure samples of HD, copula function is used to describe the dependence between strength failure and stiffness degradation failure.

Strength failure occurred earlier than degradation failure under high level accelerated condition; degradation failure occurred earlier than strength failure under medium- or low-level accelerated condition. Gumbel copula is the optimum copula function for dependence modeling of strength failure and stiffness degradation failure. Dependent competing failure reliability of HD is larger than independent competing failure reliability.

The reliability evaluation method of dependent competing failure of HD with strength failure and degradation failure is first proposed. Performance degradation experiments during accelerated life test (ALT), step-down ALT and life test under rated condition are conducted for Wiener process based step-down accelerated performance degradation modeling.

This paper aims to present simulation results of a harmonic drive (HD) with involute flexspline (FS) profiles based on two-dimensional (2-D) finite element analysis (FEA).

First, the mathematical model of the FS with involute tooth profile was developed using a straight-edge rack cutter based on the theory of gearing. Then the engaging circular spline (CS) with conjugate tooth profile of FS was derived based on the enveloping theory and theory of gearing. Additionally, a mesh generation program was developed to discretize the FS based on the mathematical model. An elliptical wave generator (WG) was inserted into the FS, and a torque was applied to drive the FS meshing with the CS. The WG and the CS were both assumed to be rigid in the finite element model.

Finally, a 2-D FEA was conducted to explore the stress distribution on the FS, the engagement movement of the FS, the torsional stiffness and the engaged area of teeth of the HD under various conditions. Moreover, this research also studied the effect of changing pressure angle of the involute FS on the performance of the HD.

The simulation model and methodology presented in this paper paved the way for further investigation and optimization of the HD with involute tooth profile FS and conjugate CS.

The simulation model of HD is established on conjugate shape based on the theory of gearing and an automatic mesh generation program is developed to generate the finite element model. The characteristics of the HD can thus be simulated according to the developed model.

The purpose of this study is to provide insights into the way in which understanding and implementation of disruptive technology, specifically big data analytics and the Internet of Things (IoT), have changed over time. The study also examines the ways in which research in supply chain and related fields differ when responding to and managing disruptive change.

This study follows a four-step systematic review process, consisting of literature collection, descriptive analysis, category selection and material evaluation. For the last stage of evaluating relevant issues and trends in the literature, the latent semantic analysis method was adopted using Leximancer, which allows more rapid, reliable and consistent content analysis.

The empirical analysis identified key research trends in big data analytics and IoT divided over two time-periods, in which research demonstrated steady growth by 2015 and the rapid growth was shown afterwards. The key finding of this review is that the main interest in recent big data is toward overlapping customer service, support and supply chain network, systems and performance. Major research themes in IoT moved from general supply chain and business information management to more specific context including supply chain design, model and performance.

In addition to providing more awareness of this research approach, the authors seek to identify important trends in disruptive technologies research over time.

The purpose of this paper is to provide a micro historical account of the work of a key Chinese educational reformer, Tao Xingzhi (1891–1946), who transformed educational ideas from John Dewey to effect social and cultural change in 1920s–1940s China.

This paper examines English and Chinese language sources, including Tao’s poetry, to present a fresh analysis of Tao’s epistemological life history. It draws upon transnational historical approaches to chart the multidirectional circulation of progressive education philosophies around the globe. It also explores some conceptual dimensions of Chinese historical thinking and historiographical strategies.

Tao Xingzhi engaged in critical intercultural knowledge exchange in implementing educational reforms in China. He blended and critiqued Chinese and Deweyian educational philosophies to create unique educational reform, which involved reversing some of Dewey’s approaches as well as adapting others.

This paper foregrounds Tao Xingzhi’s agency in transforming some of Dewey’s ideas in the Chinese context and challenges studies that adopt an “impact-response” approach to Tao’s contribution, which suggest a one-way flow of knowledge from a “modern” West to a “traditional” China. It brings hitherto unexplored Chinese language sources to an English-speaking audience, particularly Tao’s poetry, to gain new historical insights into Tao’s educational reforms. It contributes to transnational understandings of the multidirectional flows of knowledge about Progressive educational philosophies around the world.

This paper aims to investigate the thermal stability and hydrophobicity of difference alkyl chain of silanes with silicon (Si) micro- and nanoparticles.

Sol-gel methods have been used to design superhydrophobic glass substrates through surface modification by using low-surface-energy Isooctyl trimethoxysilane (ITMS) and Ethyl trimethoxysilane (ETMS) solution. Hierarchical double-rough scale solid surface was built by Si micro- and nanoparticles to enhance the surface roughness. The prepared sol was applied onto glass substrate using dip-coating method and was dried at control temperature of 400°C inside the tube furnace.

The glass substrate achieved the water contact angle as high as 154 ± 2° and 150.4 ± 2° for Si/ITMS and Si/ETMS films, respectively. The Si/ITMS and Si/ETMS also were equipped with low sliding angle as low as 3° and 5°, respectively. The Si micro- and nanoparticles in the coating system have created nanopillars between them, which will suspend the water droplets. Both superhydrophobic coatings have showed good stability against high temperature up to 200°C as there are no changes in WCA shown by both coatings. Si/ITMS film sustains its superhydrophobicity after impacting with further temperature up to 400°C and turns hydrophobic state at 450°C.

Findings will be useful to develop superhydrophobic coatings with high thermal stability.

Sol method provides a suitable medium for the combination of organic-inorganic network to achieve high hydrophobicity with optimum surface roughness.

Application of different alkyl chain groups of silane resin blending with micro- and nanoparticles of Si pigments develops superhydrophobic coatings with high thermal stability.