An Automatic Ship Detection Method Based on Local Gray-Level Gathering Characteristics in SAR Imagery

This paper proposes an automatic ship detection method based on gray-level gathering characteristics of synthetic aperture radar (SAR) imagery. The method does not require any prior knowledge about ships and background observation. It uses a novel local gray-level gathering degree (LGGD) to characterize the spatial intensity distribution of SAR image, and then an adaptive-like LGGD thresholding and filtering scheme to detect ship targets. Experiments on real SAR images with varying sea clutter backgrounds and multiple targets situation have been conducted. The performance analysis confirms that the proposed method works well in various circumstances with high detection rate, fast detection speed and perfect shape preservation

The Coal Mine Accident Causation Model Based on the Hazard Theory

AbstractOn the basis of the summary of the existing research, first of all, the essential factors of coal mine accidents was differentiated and analyzed, and the technology equipment defects was believed to be the essential reasons that affect the coal mine safety. And then using the hazard theory the accident causation in coal mine production system has been divided, and it was believed that coal mine hazard sources consisted of inherent hazards, technology equipment defects and safety management misconducts. On this basis, the coal mine accident causation model on a combination of hazard theory and energy accidental releasing theory was established. Finally, this model was used to analyze the roof-fall accident of Baishui Coal Mine

Nanomechanical Resonators Based on Quasi-two-dimensional Materials

Advances in nanotechnology lead to the development of nano-electro-mechanical systems (NEMS) such as nanomechanical resonators with ultra-high resonant frequencies. The ultra-high-frequency resonators have recently received significant attention for wide-ranging applications such as molecular separation, molecular transportation, ultra-high sensitive sensing, high-frequency signal processing, and biological imaging. It is well known that for micrometer length scale, first-principles technique, the most accurate approach, poses serious limitations for comparisons with experimental studies. For such larger size, classical molecular dynamics (MD) simulations are desirable, which require interatomic potentials. Additionally, a mesoscale method such as the coarse-grained (CG) method is another useful method to support simulations for even larger system sizes. Furthermore, quasi-two-dimensional (Q2D) materials have attracted intensive research interest due to their many novel properties over the past decades. However, the energy dissipation mechanisms of nanomechanical resonators based on several Q2D materials are still unknown. In this work, the addressed main issues include the development of the CG models for molybdenum disulphide (MoS2), investigation of the mechanism effects on black phosphorus (BP) nanoresonators and the application of graphene nanoresonators. The primary coverage and results of the dissertation are as follows: Method development. Firstly, a two-dimensional (2D) CG model for single layer MoS2 (SLMoS2) is analytically developed. The Stillinger-Weber (SW) potential for this 2D CG model is further parametrized, in which all SW geometrical parameters are determined analytically according to the equilibrium condition for each individual potential term, while the SW energy parameters are derived analytically based on the valence force field model. Next, the 2D CG model is further simplified to one-dimensional (1D) CG model, which describes the 2D SLMoS2 structure using a 1D chain model. This 1D CG model is applied to investigate the relaxed configuration and the resonant oscillation of the folded SLMoS2. Owning to the simplicity nature of the 1D CG model, the relaxed configuration of the folded SLMoS2 is determined analytically, and the resonant oscillation frequency is derived analytically. Considering the increasing interest in studying the properties of other 2D layered materials, and in particular those in the semiconducting transition metal dichalcogenide class like MoS2, the CG models proposed in current work provide valuable simulation approaches. Mechanism understanding. Two energy dissipation mechanisms of BP nanoresonators are focused exclusively, i.e. mechanical strain effects and defect effects (including vacancy and oxidation). Vacancy defect is intrinsic damping factor for the quality (Q)-factor, while mechanical strain and oxidation are extrinsic damping factors. Intrinsic dissipation (induced by thermal vibrations) in BP resonators (BPRs) is firstly investigated. Specifically, classical MD simulations are performed to examine the temperature dependence for the Q-factor of the single layer BPR (SLBPR) along the armchair and zigzag directions, where two-step fitting procedure is used to extract the frequency and Q-factor from the kinetic energy time history. The Q-factors of BPRs are evaluated through comparison with those of graphene and MoS2 nanoresonators. Next, effects of mechanical strain, vacancy and oxidation on BP nanoresonators are investigated in turn. Considering the increasing interest in studying the properties of BP, and in particular the lack of theoretical study for the BPRs, the results in current work provide a useful reference. Application. A novel application for graphene nanoresonators, using them to self-assemble small nanostructures such as water chains, is proposed. All of the underlying physics enabling this phenomenon is elucidated. In particular, by drawing inspiration from macroscale self-assembly using the higher order resonant modes of Chladni plates, classical MD simulations are used to investigate the self-assembly of water molecules using graphene nanoresonators. An analytic formula for the critical resonant frequency based on the interaction between water molecules and graphene is provided. Furthermore, the properties of the water chains assembled by the graphene nanoresonators are studied

Modeling Sketching Primitives to Support Freehand Drawing Based on Context Awareness

Freehand drawing is an easy and intuitive method for thinking input and output. In sketch based interface, there lack support for natural sketching with drawing cues, like overlapping, overlooping, hatching, etc. which happen frequently in physical pen and paper. In this paper, we analyze some characters of drawing cues in sketch based interface and describe the different types of sketching primitives. An improved sketch information model is given and the idea is to present and record design thinking during freehand drawing process with individuality and diversification. The interaction model based on context is developed which can guide and help new sketch-based interface development. New applications with different context contents can be easily derived from it and developed further. Our approach can support the tasks that are common across applications, requiring the designer to only provide support for the application-specific tasks. It is capable of and applicable for modeling various sketching interfaces and applications. Finally, we illustrate the general operations of the system by examples in different applications

Research on the Problem of Old-Age Care in China From the Perspective of Ethics

The elders are an important driving force for economic development, social progress and national prosperity. The care of the elderly, as a universal world problem, is related to their dignity, human rights and social stability. Since 2000, China has stepped into the threshold of an aging society. With the increasing aging population and the influence of population, economy, culture, politics and other uniquely national conditions, the conflicts and problems over providing for the aged are more complicated and severe. It has become an urgent issue in China how to solve a series of ethical dilemmas of providing for the aged caused by the aging population.Firstly, we use the data of the 2018 Chinese Longitudinal Healthy Longevity Survey (CLHLS) for positivist research, and then adopt the ordered Probit regression model for analysis. Secondly, we present and discuss the existing ethical problems of providing for the aged in society: firstly, the unfairness of allocation of resources in the society for providing for the aged; secondly, the dilution of concept of filial piety in family; thirdly, the weakening of the trend of respecting the elderly in society; last but not least, the lack of good in old-age security system. In view of the above-mentioned ethical problems of providing for the aged in China, we propose some solutions, namely, fairly distributing old-age resources in society; promoting the cultural tradition of filial piety; improving the system of endowment policy. Focusing on the ethical issues of old-age care, this paper provides some ethical thoughts for the solution of them

Pore structure characteristics of middle and low rank coals and their influence on gas desorption characteristics

The pore structure of coal is an important factor affecting gas storage and migration. In order to further study the gas desorption characteristics of low and medium metamorphic coals, 6 sets of coal samples from the Fukang mining area were selected for mercury intrusion and gas desorption experiment. Mercury intrusion and extrusion curves of coal samples were drawed, the pore structure characteristics of each pore segment were counted, the gas desorption curve was drawed, and the pore morphology, pore volume, pore specific surface area and volume fractal dimension of coal and their influence on the gas desorption capacity and desorption rate were analyzed. The results show that there are different proportions of open pores in coal samples. Macropores are mainly composed of open pores, the middle and small pores are mainly composed of semi-closed pores, and the micropores are mainly composed of closed pores. In addiction, the total pore volume are mainly contributed by micropores and macropores, and micropores contributes the most to the total specific surface area. By drawing the gas desorption curve and the desorption rate scatter diagram, it is found that the gas desorption amount increases rapidly with the desorption time and then tends to a stable value, and then the fitting finds that the gas desorption curve of middle and low rank coal can be expressed by 1/Q=m/t0.75+n, the degree of fitting is above 0.995, where m is a parameter related to the gas desorption rate, n is a parameter related to the desorption volume constant,and the coefficient of 0.75 may be related to the degree of coal metamorphism, and the desorption curves with different degrees of metamorphism can be analyzed in the later stage. And the desorption rate decreases exponentially with the desorption time. Fitting the pore structure characteristics of different pore sizes with the desorption characteristic parameters, it is found that the gas in the macropores is preferentially desorbed in the initial stage of desorption. As the pore size decreases, the priority rate gradually decreases. The fractal dimension of mesopores and macropores is between 2.879 1−2.991 5, which has obvious fractal characteristics. It is proposed that the initial desorption velocity and fractal dimension show a significant positive correlation. The relationship between n value and fractal dimension is not obvious

Digitalization, resource misallocation and low-carbon agricultural production: evidence from China

With the rapid development of digital technologies such as artificial intelligence, big data and cloud computing, China’s agricultural production is entering a new era characterized by digitalization. Based on provincial panel data of China from 2013 to 2020, this paper adopts the system GMM and mediating effects model to systematically examine the impact of digitalization on low-carbon agricultural production from the perspective of resource misallocation. The results indicate that digitalization can significantly curb agricultural carbon emissions and thus promote low-carbon agricultural production, and this finding still holds after the robustness test. The heterogeneity analysis indicates that the inhibiting effect of digitalization on agricultural carbon emissions is most pronounced in the eastern region relative to the central and western regions (the regression coefficients are −0.400 and −0.126 respectively). Further mechanism analysis suggests that digitalization can reduce agricultural carbon emissions by correcting the widespread capital and labor misallocation in agricultural factor markets. The findings of this study provide significant policy implications for low-carbon agricultural production in China

Novel-view Synthesis and Pose Estimation for Hand-Object Interaction from Sparse Views

Hand-object interaction understanding and the barely addressed novel view synthesis are highly desired in the immersive communication, whereas it is challenging due to the high deformation of hand and heavy occlusions between hand and object. In this paper, we propose a neural rendering and pose estimation system for hand-object interaction from sparse views, which can also enable 3D hand-object interaction editing. We share the inspiration from recent scene understanding work that shows a scene specific model built beforehand can significantly improve and unblock vision tasks especially when inputs are sparse, and extend it to the dynamic hand-object interaction scenario and propose to solve the problem in two stages. We first learn the shape and appearance prior knowledge of hands and objects separately with the neural representation at the offline stage. During the online stage, we design a rendering-based joint model fitting framework to understand the dynamic hand-object interaction with the pre-built hand and object models as well as interaction priors, which thereby overcomes penetration and separation issues between hand and object and also enables novel view synthesis. In order to get stable contact during the hand-object interaction process in a sequence, we propose a stable contact loss to make the contact region to be consistent. Experiments demonstrate that our method outperforms the state-of-the-art methods. Code and dataset are available in project webpage https://iscas3dv.github.io/HO-NeRF

Governance strategies for end-of-life electric vehicle battery recycling in China: A tripartite evolutionary game analysis

End-of-life (EOL) electric vehicle (EV) batteries have both economic and environmental benefits if recycled in an environmentally friendly manner while they may cause environmental pollution if treated improperly. China is currently working hard to promote the development of a circular economy by EOL EV battery recycling. However, conflicts of interest among electric vehicle manufacturers (EVMs), consumers, and the government often hinder efficient recycling. This study constructs a tripartite evolutionary game model under the condition of bounded rationality, analyzes the evolutionary stability strategy of three participants, and combines with numerical simulation to explore the feasible governance strategies of EOL EV battery recycling. The results show that four evolutionary stable strategies (ESSs) correspond to the three stages of the EOL EV battery recycling industry: early stage, development stage, and maturity stage. In the early stage, the punishment strategy is more critical to motivate EVMs and consumers to actively participate in battery recycling. The subsidy mechanisms can influence the strategic choices of the three participants, but the excessive subsidy is not conducive to the sustainable development of the EOL EV battery industry. In addition, when the industry matures, the government will gradually decrease intervention, thereby realizing the development path of EOL EV battery recycling from exogenous government supervision to endogenous profit drive