Developing High Performance Holographic Photopolymers

The focus of this thesis is to develop novel holographic photopolymers with high performance and summarize the fundamental understanding gained from such process. The performance of holographic photopolymers mainly refers to two parameters here, i.e., refractive index modulation and haze, which usually limit the development of emerging holographic applications in areas like data storage and see-through display. To improve the two parameters, a variety of chemical strategies were utilized and investigated. Firstly, high-refractive-index thiol-ene monomers were utilized together with a reactive linear polymer binder to achieve an extremely high refractive index modulation over 0.04. With the help of reactive binders, diffusional blurring that lowers the achievable refractive index modulation at high spatial frequency was significantly alleviated. Next, the effects of diffusion and reaction on the performance of holographic photopolymers were studied in the above-mentioned thiol-ene system by employing various chemical methods to alter the diffusion and reaction processes. In the study, an optimum ratio between reaction and diffusion was found to be crucial for achieving high performance in a specific material system, while the alteration of radical stability, reactivity of reactive binder and gel point of writing monomers all had an impact on the performance. Based on these trends, allyl sulfide moieties capable of addition-fragmentation chain transfer were introduced into polymer binder to realize the light-regulated viscosity reduction of recording media to improve the performance of formulations where the diffusion of monomer is limited; meanwhile, a low haze was maintained by a potential crosslinking between photopolymer and binder due to the dynamic exchange. Additionally, through the control of reaction kinetics and thermodynamics, haze in a conventional two-stage holographic photopolymer was systematically studied and largely reduced.</p

Organic Anti-counterfeiting Techniques in China

The development of organic label anti-counterfeiting techniques in China has been introduced, including three generations of the techniques, especially the third-generation QR Code organic anti-counterfeiting traceable label. How to use the anti-counterfeiting techniques to enable the organic products to be “easy in identification, traceable in information and controllable in quantity”, how to enhance consumers’ recognition and how to power the government's regulation enforcement on organic market were demonstrated

Input-output-based genuine value added and genuine productivity in China\u27s industrial sectors (1995-2010)

The rapid growth of China\u27s economy has brought about huge losses of natural capital in the form of natural resource depletion and damages from carbon emissions. This paper recalculates value added, capital formation, capital stock, and related multifactor productivity in China\u27s industrial sectors by further developing the genuine savings method of the World Bank. The sector-level natural capital loss was calculated using China\u27s official input–output table and their extensions for tracing final consumers. The capital output elasticity in the productivity estimation was adjusted based on these tables. The results show that although the loss of natural capital in China\u27s industrial sectors in terms of value added has slowed, the impacts on their productivity during the past decades is still quite clear

A general physics-based data-driven framework for numerical simulation and history matching of reservoirs

This paper proposed a general physics-based data-driven framework for numerical mod-eling and history matching of reservoirs that achieves a good balance of flow physics and actual field data. Underground reservoir is easily discretized in this framework as a flow network composed of one-dimensional connection elements, each of which is defined by two flow characteristic parameters. Each one-dimensional connection element is divided into some grids, and the cross-sectional area and permeability of the grids on the same connection element are equal. The fully implicit scheme of flow equations and the Newton iteration nonlinear solver concurrently solve all unknown quantities. Then, using actual field data, the simultaneous perturbation stochastic approximation algorithm is used to invert flow characteristic parameters of each connection element, and the unequal constraint that the volume of connection elements should not exceed the total reservoir volume is added to control the data-driven process. To demonstrate the unequal constraint is physical, a test case of a waterflooding reservoir with a high permeability zone is given. A waterflooding reservoir example with five injectors and four producers is used to demonstrate that this framework outperforms earlier techniques, and another case with single-phase depletion development is used to demonstrate that this framework has a high generalization for flow models. In addition, this data-driven framework based on physics is expected to serve as a reference for other fields of science and engineering.Cited as: Rao, X., Xu, Y., Liu, D., Liu, Y., Hu, Y. A general physics-based data-driven framework for numerical simulation and history matching of reservoirs. Advances in Geo-Energy Research, 2021, 5(4): 422-436, doi: 10.46690/ager.2021.04.0

High-performance Self-lubricating Ceramic Composites with Laminated-graded Structure

High-performance ceramic composites are potential candidates for the application of wear-resistance components because of their excellent properties. Nevertheless, many problems, such as high friction coefficient of ceramic material and poor mechanical properties of ceramic-matrix self-lubricating composites, limit a wider range of applications of these composites in tribological areas. Therefore, improving high-toughness ceramic-matrix self-lubricating materials for practical applications is significant. This study proposes a new design for ceramic self-lubricating composites to overcome the conflict between their mechanical and tribological properties. Complying with the design principle of bionic and graded composites, two kinds of self-lubricating ceramic composites with laminated-graded structure were prepared, and their mechanical and tribological properties were studied. The results show that this newly developed ceramic composite has achieved satisfactory strength and tribological properties compared with the traditional ceramic self-lubricating composites. The bending strength reached the same level as the properties of general monolithic ceramics. In the temperature range of 25-800 °C, the friction coefficient of composites was less than 0.55, which was about half of that of monolithic ceramics