Research on a Rice Counting Algorithm Based on an Improved MCNN and a Density Map

The thousand grain weight is an index of size, fullness and quality in crop seed detection and is an important basis for field yield prediction. To detect the thousand grain weight of rice requires the accurate counting of rice. We collected a total of 5670 images of three different types of rice seeds with different qualities to construct a model. Considering the different shapes of different types of rice, this study used an adaptive Gaussian kernel to convolve with the rice coordinate function to obtain a more accurate density map, which was used as an important basis for determining the results of subsequent experiments. A Multi-Column Convolutional Neural Network was used to extract the features of different sizes of rice, and the features were fused by the fusion network to learn the mapping relationship from the original map features to the density map features. An advanced prior step was added to the original algorithm to estimate the density level of the image, which weakened the effect of the rice adhesion condition on the counting results. Extensive comparison experiments show that the proposed method is more accurate than the original MCNN algorithm.     

Termolecular chemistry facilitated by radical-radical recombinations and its impact on flame speed predictions

Recent theoretical studies have shown that termolecular chemistry can be facilitated through reactions of flame radicals (H, O, and OH) or O₂ with highly-energized collision complexes (either radical or stable species) formed in exothermic reactions. In this work, radical-radical recombination reaction induced termolecular chemistry and its impact on combustion modeling was studied. Two recombination reactions, H + CH₃ + M → CH₄ + M and H + OH + M → H₂O + M, were analyzed using ab-initio master equation analyses guided by quasiclassical trajectory results. The dynamics results and the master equation calculations indicate that CH₄^? and H₂O^? (formed in the two radical-radical reactions outlined above) react rapidly with flame radicals and O₂ at rates that are competitive with collisional cooling. The addition of these processes into conventional combustion modeling requires two modifications: the inclusion of the new nonthermal termolecular reaction rates and the simultaneous reduction of the competing recombination reaction rates. The former is described with newly derived Arrhenius expressions based on quasiclassical trajectories, and the latter is achieved by perturbing the recombination reaction rate during the simulation. Kinetic modeling was used to gauge the impact of including this nonthermal chemistry for H₂/CH₄-air laminar flames speeds. Inclusion of this nonthermal chemistry has a noticeable impact on simulated flame speeds. The procedure developed here can be utilized to properly quantify the effects of such nonthermal reactions in macroscopic kinetic models.     

凹凸棒石/硅橡胶复合材料的热氧化降解和老化性能研究

本文采用高压均质结合对辊挤压工艺对天然凹凸棒石进行棒晶解离得到了纯度较高和比表面积较大(133.7 m²/g)的纳米解离凹凸棒石. 进一步通过机械共混法分别将天然凹凸棒石和纳米解离凹凸棒石与硅橡胶生胶复合制备了天然凹凸棒石-硅橡胶和纳米解离凹凸棒石-硅橡胶材料,研究了天然凹凸棒石和纳米解离凹凸棒石对凹凸棒石/硅橡胶复合材料热氧化降解和老化性能的影响. 结果表明,天然凹凸棒石-硅橡胶和纳米解离凹凸棒石-硅橡胶在300 oC热氧老化处理0.5 h后,相比于纯硅橡胶,初始5%失重温度从385 oC提高至396∽399 oC. 系列表征结果表明,天然凹凸棒石和纳米解离凹凸棒石增强了纳米粒子与硅橡胶之间的相互作用从而抑制了纳米颗粒聚集,并且可显著提高硅橡胶侧链Si-CH₃的保存率,从而提高了该复合材料的热氧化降解和老化性能. 此外,纳米解离凹凸棒石可大大抑制纳米粒子的长大;因此老化后,纳米解离凹凸棒石-硅橡胶表现出了比硅橡胶(10.6%、7.4%和5.0%)更高的拉伸强度、断裂伸长率和撕裂强度保留率(40.6%、34.9% 和30.1%).     

Ability of the radial basis function approach to extrapolate nuclear mass

The ability of the radial basis function(RBF) approach to extrapolate the masses of nuclei in neutron-rich and superheavy regions is investigated in combination with the Duflo-Zuker(DZ31), Hartree–Fock-Bogoliubov(HFB27), finite-range droplet model(FRDM12) and Weizs?cker-Skyrme(WS4) mass models. It is found that when the RBF approach is employed with a simple linear basis function, different mass models have different performances in extrapolating nuclear masses in the same region, and a single mass model may have different performances when it is used to extrapolate nuclear masses in different regions. The WS4 and FRDM12 models(two macroscopic–microscopic mass models), combined with the RBF approach, may perform better when extrapolating the nuclear mass in the neutron-rich and superheavy regions.     

Joule–Thomson expansion of RN-AdS black hole immersed in perfect fluid dark matter

In this paper, we study the Joule–Thomson expansion for RN-Ad S black holes immersed in perfect fluid dark matter. As perfect fluid dark matter is one of the dark matter candidates, we are interested in how it influences the thermodynamic properties of black holes. Firstly, the negative cosmological constant could be interpreted as thermodynamic pressure and its conjugate quantity as the thermodynamic volume, which give us more physical insights into the black hole. Moreover, we derive the thermodynamic definitions and study the critical behaviour of the black hole. Secondly,the explicit expression of Joule–Thomson coefficient is obtained from the basic formulas of the pressure, the volume, the entropy and the temperature. Then, we obtain the inversion curves in terms of charge Q and parameter λ. Furthermore, we analyse the isenthalpic curve in T–P graph with the cooling–heating region determined by the inversion curve. At last, we derive the ratio of minimum inversion temperature to critical temperature and compare the result with that in the RN-Ad S case.     

Charged torus-like black holes as heat engines

We investigate the thermodynamical properties of charged torus-like black holes and take it as the working substance to study the heat engines. In the extended phase space, by interpreting the cosmological constant as the thermodynamic pressure, we derive the thermodynamical quantities by the first law of black hole thermodynamics and obtain the equation of state. Then, we calculate the efficiency of the heat engine in the Carnot cycle as well as the rectangular cycle,and investigate how the efficiency changes with respect to volume. In addition, to avoid a negative temperature, we emphasize that the charge of this black hole cannot be arbitrary. Last,we check the calculation accuracy of a benchmark scheme and discuss the upper bound and lower bound for charged torus-like black hole in the scheme.     

Numerical simulation of the soliton solutions for a complex modified Korteweg—de Vries equation by a finite difference method

In this paper,a Crank-Nicolson-type finite difference method is proposed for computing the soliton solutions of a complex modifed Korteweg de Vries(MKdV)equation(which is equivalent to the Sasa-Satsuma equation)with the vanishing boundary condition.It is proved that such a numerical scheme has the second order accuracy both in space and time,and conserves the mass in the discrete level.Meanwhile,the resuling scheme is shown to be unconditionally stable via the von Nuemann analysis.In addition,an iterative method and the Thomas algorithm are used together to enhance the computational efficiency.In numerical experiments,this method is used to simulate the single-soliton propagation and two-soliton collisions in the complex MKdV equation.The numerical accuracy,mass conservation and linear stability are tested to assess the scheme's performance.     

锯齿型与扶手椅型碳化硅纳米管光电性质第一性原理研究

本文基于密度泛函理论计算分析了手性参数为(17,0)、(20,0)、(26,0) (10,10)、(12,12)、(15,15)的碳化硅纳米管的能带图,态密度及主要光学性质。结果表明：锯齿型与扶手椅型碳化硅纳米管均具有明显的半导体性质;在相近直径下,扶手椅型碳化硅纳米管带隙宽度要大于锯齿型碳化硅纳米管的带隙宽度;碳化硅纳米管的光吸收峰在100nm~200nm之间,可用于制作紫外线探测器件。     

HL-2M 主机抗扭转支撑结构计算分析

根据通电的环向场(TF)线圈在磁场作用下将产生侧向力和径向力,提出了抗扭转支撑结构方案。该方案能够降低这两种力对 TF 线圈的影响,并且保证线圈连接面的紧密接触和绝缘层不会发生相对错动。对抗扭转支撑结构进行计算分析,确定该结构的受力方式以及传力路径。结果表明,在实验运行以及极端工况下结构的应力、位移能够到达设计要求,通过疲劳计算得出抗扭转支撑结构能满足 20 年以上的实验运行,能够保证 HL-2M装置安全、平稳和可靠的运行。      

基于1085 km实地光纤链路的双波长光纤时间同步研究

在长距离高精度光纤时间同步系统中,为了减少后向反射光与光纤色散对传输精度的影响,本文在双波长光纤时间同步传输方法之上,提出了一种具有色散误差修正功能的双波长光纤时间同步传输方法.以自行研制的工程样机在长度约为800 km的实验室光纤链路上和1085 km的实地光纤链路上进行了实验测试,也是国内首次实现千公里级实地光纤时间同步传输.在实验室光纤链路上,测得传输链路色散补偿后的色散时延误差为10 ps,时间同步标准差为5.7 ps,稳定度为1.12 ps@105 s,不确定度为18.4 ps.在实地光纤链路上,测得传输链路色散补偿后的色散时延误差为60 ps,时间同步标准差为18 ps,稳定度为5.4 ps@4×10⁴ s,不确定度为63.5 ps.