基于多元线性回归与BP神经网络分析南疆巴旦木结构物理特性

运用多元线性回归与BP神经网络等多种数理统计手段对南疆巴旦木结构物理特性进行研究。基于多元线性回归及方差分析方法,对南疆巴旦木结构外形进行定义和物理参数测定,运用MATLAB软件得出,巴旦木长、宽、缝三者之间不是简单线性关系,其外形近似为关于横、竖、纵3椭圆截面对称的扁壳体;在测定对应的巴旦木果仁质量后,运用3层BP神经网络结构寻找巴旦木结构外形与果仁质量间的关系,建立相应质量预测模型。可在不破坏巴旦木外壳的情况下,通过长、宽、缝来预测巴旦木果仁的质量,从而为巴旦木无损品质分级及破壳装置设计提供理论基础。

新疆杏核破壳最佳截面的探讨

通过对新疆杏核形状结构的定义,对其结构物理特性进行分析研究,发现其核长、核宽、核厚及其之间不应仅为简单的线性关系,而可近似为关于横、竖、纵三椭圆截面对称的壳体,作为具有椭圆截面的异形薄壳壳体来研究。同时设定该壳体所受破壳压力大小一致、均匀分布,在弯矩公式中引入回转半径,简化计算;进行分析探讨其综合应力和危险截面;通过统计验证,最终得出结论:杏核破壳的最佳截面为杏核所具有的最大应力截面,即椭圆截面的最小回转半径处。

南疆杏核挤压破壳截面的探讨

南疆杏核形状结构的物理特性进行分析研究,可知其核长、宽、厚及其之间不应仅为简单的线性关系,而可近似为横、竖、纵三椭圆截面对称的壳体,作为具有椭圆截面的异形薄壳壳体来研究.同时设定该壳体所受破壳压力大小一致、均匀分布,在弯矩公式中引入回转半径L进行简化计算,分析探讨其综合应力和危险截面,结论是杏核破壳的最佳截面为杏核所具有的最大应力截面,即椭圆截面的最小回转半径处.

Effect of high-voltage discharge non-thermal plasma on g-C_3N_4 in a plasma-photocatalyst system

The synergistic effect of high voltage discharge non‐thermal plasma(NTP)and photocatalysts on contaminant removal has repeatedly confirmed by plenty of researches.Most previous plasma‐photocatalyst synergistic systems focused on the utilization of the ultraviolet light but ignored the visible light generated by high voltage discharge.Graphitic carbon nitride(g‐C3N4),a metal‐free semiconductor that exhibits high chemical stability,can utilize both the ultraviolet and visible light from high voltage discharge.However,the synergistic system of NTP and g‐C3N4 has been researched little.In this paper,the effect of NTP generated by dielectric barrier discharge(DBD)on g‐C3N4 is studied by comparing the photocatalytic activities,the surface physical structure and the surface chemical characteristics of pristine and plasma treated g‐C3N4.Experimental results indicate that the DBD plasma can change the physical structure and the chemical characteristics and to further affect the photocatalytic activity of g‐C3N4.The effect of NTP on g‐C3N4 is associated with the discharge intensity and the discharge time.For a long time scale,the effect of NTP on g‐C3N4 photocatalysts presents a periodic change trend.

Joint inversion of gravity and multiple components of tensor gravity data

Geological structures often exhibit smooth characteristics away from sharp discontinuities. One aim of geophysical inversion is to recover information about the smooth structures as well as about the sharp discontinuities. Because no specific operator can provide a perfect sparse representation of complicated geological models, hyper-parameter regularization inversion based on the iterative split Bregman method was used to recover the features of both smooth and sharp geological structures. A novel preconditioned matrix was proposed, which counteracted the natural decay of the sensitivity matrix and its inverse matrix was calculated easily. Application of the algorithm to synthetic data produces density models that are good representations of the designed models. The results show that the algorithm proposed is feasible and effective.

Manufacture of Flax Reinforced PP Laminates and Research on the Tensile Properties

Flax fiber was used to reinforce Polypropylene （PP） owing to its lower impact on environment and suitable mechanical behaviors. To overcome the difficulty of penetrating fibers due to the high viscosity of thermo-plastic resin, PP filaments wrapping around the linen yam produced commingled yams, which were woven into fabrics as preforms to make laminates by optimum hot-pressing technology. The effects of fiber volume fraction, fabric density and structure on tensile properties of composites were researched through analyzing the tensile test results and the scanning electronic microscope （SEM） micrographs of fracture surface. Conclusions are drawn that the properties of laminates with fiber volume fraction of 0.50 are better than those with the other two fractions. For plain structure, the tensile properties in warp direction decrease according to the increase of weft density while in weft direction increase. For different fabric structures, properties of laminates with structures of plain 3, twill 2/2 and twill 3/1 increase gradually. And properties in weft direction are prior to those in warp direction for each laminate.

Effect of pH value and calcination temperature on synthesis and characteristics of Cu-Ni nano-alloys

Cu?Ni nano-alloys were prepared using precursors synthesized by the citrate-gel method. The effects of initial solution pH value and calcination temperature on the composition, crystalline structure, purity, morphology, homogeneity and grain size of Cu?Ni nanoparticles were investigated. Both the parameters significantly affect the crystalline structure, composition and grain size. Cu?Ni alloys prepared at pH value of 1 do not contain impurities, and their compositions are Cu0.42Ni0.58, Cu0.45Ni0.55 and Cu0.52Ni0.48 reduced at 300, 400 and 500 °C, respectively. The grain size grows with the increase of calcination temperature for the precursor prepared at pH values of 1.6 and 3. The Ni content of the alloys gradually increases with the increase of calcination temperature at pH value of 3.

Hydraulic Characteristics of Low Crested Structures under Wave Attack

Two-dimensional physical models of low crested breakwaters were tested to establish the effect of water depth, crest width, slope, stone size, core permeability and incident wave characteristics on the wave transformation processes. The structure of the breakwaters can be used as coastal protection system by reducing the amount of incoming wave energy. Effect of slope, core permeability, water depth and incident wave characteristics on the stability was also studied. The breakwater model consisted of a core and two armour layers attacked by irregular waves. This paper discusses and compares the test results with the existing design equations. In general, the existing design equations do not seem to predict the wave transmission and reflection accurately for the range of test data. In the range of variable tested, it was observed that the water depth, crest width and wave period have a significant influence on wave transmission process. Further, results show strong influence of the water depth and wave period on the wave reflection process. The structural stability of low crested breakwaters is very much affected by the water depth and wave period.

Physical characteristics with SPP in the metallic nanowires structure

In this work, the terahertz （THz） electromotive force （EMF） of the surface plasmon （SP） electric field and field strength was investigated in its propagation direction. Based on the nanowires structure, we introduced physical models which were light wave energy of surface plasmon polariton （SPP） pulse and the variation of EMF changes in the active condition. Results of theory and verification showed SPP generated EMF with 10-2-10 V among wire radii of 5-30 nm; the electric field was up to 10^5-1066V/cm in the radius of 5 nm; the electric field intensity induced localization at λ=850 nm, and at the same time light intensity amplified 40 times. The characteristics which are femtosecond SPP pulse response and force-field amplifier in this work are significant for nonlinear spectroscopy research.

Remarkable anisotropic phonon response in uniaxially strained few-layer black phosphorus

Black phosphorus （BP） is a good candidate for studying strain effects on two- dimensional （2D） materials beyond graphene and transition-metal dichalcogenides. This is because of its particular ability to sustain high strain and remarkably anisotropic mechanical properties resulting from its unique puckered structure. We here investigate the dependence of lattice vibrational frequencies on cry- stallographic orientations in uniaxially strained few-layer BP by in-situ strained Raman spectroscopy. The out-of-plane A1 mode is sensitive to uniaxial strain along the near-armchair direction whereas the in-plane B2g and A2 modes are sensitive to strain in the near-zigzag direction. For uniaxial strains applied away from these directions, all three phonon modes are linearly redshifted. Our experimental observation is explained by the anisotropic influence of uniaxial tensile strain on structural properties of BP using density functional theory. This study demonstrates the possibility of selective tuning of in-plane and out-of-plane phonon modes in BP by uniaxial strain and makes strain engineering a promising avenue for extensively modulating the optical and mechanical properties of 2D materials.