具有固定匹配数的单圈图的A∝-谱半径

对于任意的α∈[0,1],Nikiforov提出了矩阵A_α(G)=αD(G)+(1-α)A(G),记为图G的A_α-矩阵,其中A(G)是G的邻接矩阵,D(G)是G的度对角矩阵.矩阵A_α(G)的最大特征值称为图G的A_α-谱半径.考虑固定匹配数的所有单圈图,确定了前三个具有最大A_α-谱半径的图.     

几乎单DD-群

研究几乎单的DD-群, 证明了几乎单群G不是一个DD-群, 如果G不是下列群中的一个: 1) 散在单群M₂₂, J₂, Co₁, Fi'₂₄, McL, Th, B, 以及M₁₂或者J₂的自同构群; 2) 交错群A₅, A₆, A₇, A₉, A₁₀, A₁₆, S₅, Aut(A₆), S₈, S₁₀, 或者A_n(62≤n≤205); 3) L₃(2), Aut(L₃(3)), 或者L₂(q), 其中q=4, 5, 7, 9, 11。     

Screening and flocculating properties of bioflocculant-producing microorganisms

Screening of bioflocculant-producing microorganisms was carried out. A strain that secreted excellent bioflocculant was isolated from municipal sewage using the spread plate technique, identified as Klebsiella sp. by the analytical profile index (API) identification system, and named A₉. Several important factors that had an effect on A₉’s bioflocculant-producing and flocculating activity were studied. A total of 4 g/L Kaolin suspension was used to measure the flocculating activity of the bioflocculant from A₉. It was found that maltose and urea were A₉’s best carbon and nitrogen sources, respectively, and the flocculating activity of the flocculating agent from A₉ was markedly increased by the addition of trivalent cations such as Fe3+ and Al3+; furthermore, the bioflocculant produced by A₉ was most effective when the pH value was 6.0.     

关于一类高阶复微分方程解的增长性

该文研究了一类高阶线性微分方程f ^(k)+A_k-1 f ^(k-1)+…+A₁ f '+A₀ f=F(z)解的增长性,其中A₀,A₁,…,A_k-1,F(z)是整函数,并且A₀、A₁是另一个2阶线性方程的非平凡解. 推广了龙见仁等得到的结果.     

Calculation Models of Mass Action Concentrations for Metallic Melts Involving Monotectic

Based on the phase diagrams, measured activities as well as△Gm and △Gxs, calculating models of mass action concentrations for metallic melts involving monotectic have been formulated. The calculated results agree with practice on the whole, showing that the models deduced generally can reflect the structural characteristics of these melts. The metastable compounds formed in the melts are of the types A₂B₃, AB₂, A₂B₃ or AB and A₂B₃+AB etc..     

Mechanical properties of directionally solidified lead-antimony alloys

The Pb-17wt% Sb alloy was directionally solidified under two solidification conditions: with different temperature gradients (G=0.93–3.67 K/mm) at a constant growth rate (V=17.50 μm/s) and with different growth rates (V=8.3–497 μm/s) at a constant temperature gradient (G=3.67 K/mm) in a Bridgman furnace. Microstructure parameters, such as primary dendrite arm spacing (λ₁), secondary dendrite arm spacing (λ₂), and dendrite tip radius (R), were measured. The microhardness (Hv) and ultimate tensile strength (σ) of the directional solidification samples were also measured. The influences of solidification and microstructure parameters on Hv and σ were investigated. The results obtained in this work were compared with similar experimental researches in literatures. It is shown that the Hv and σ values increase with the increase of G and V, but decrease with the increase of λ₁, λ₂, and R.     

不同覆盖措施对梁山慈竹出笋和竹笋适口性的影响

【目的】梁山慈竹(Dendrocalamus farinosus)主要以材用为主,开发其笋用价值,可提高丛生竹经济效益,同时为丛生竹笋用培育提供参考。【方法】以梁山慈竹为研究对象,采用4因素3水平正交试验设计,探讨不同覆盖材料(A₁.土壤;A₂.竹屑;A₃.糠壳)、覆盖厚度(B₁.0 cm;B₂.15 cm;B₃.30 cm)、施肥量(C₁.0 kg/丛;C₂.1.0 kg/丛;C₃.1.5 kg/丛)和覆盖时间(D₁.4月15日;D₂.4月30日;D₃.5月15日)对梁山慈竹出笋和竹笋适口性的影响;共进行9次试验处理(T1.A₁B₁C₁D₁;T2.A₁B₂C₂D₂;T3.A₁B₃C₃D₃;T4.A₂B₁C₂D₃;T5.A₂B₂C₃D₁;T6.A₂B₃C₁D₂;T7.A₃B₁C₃D₂;T8.A₃B₂C₁D₃;T9.A₃B₃C₂D₁),分析测定了其出笋量、成竹率、胸径,竹笋可食率、外观形态以及呈味物质的变化。【结果】梁山慈竹竹丛覆盖可降低其出笋而促进成竹生长,覆盖后,竹笋可食率提高38%,且以覆盖15 cm厚度的可食率最高,达47%,笋箨由暗沉的深绿色变为鲜亮的紫红色;苦味氨基酸含量、占比显著下降,鲜味氨基酸占比相对升高,草酸、单宁含量显著下降,竹笋苦涩味明显减弱,口感显著提升,以T5处理(A₂B₂C₃D₁)表现最好;本试验发现施用氮磷钾复合肥对梁山慈竹出笋、成竹和生长没有显著影响。【结论】竹丛覆盖可适度调节梁山慈竹出笋成竹,显著改善竹笋品相和适口性,覆盖不受材料、时间限制,在竹笋出土前覆盖即可,采笋则以笋尖突破覆盖物时为宜。     

播期和播量对豫南直播稻产量形成特征的影响

为探究播期和播量对豫南直播稻产量和干物质累积的影响，以水稻品种丰优香占为试验材料，设置5个播期处理，即A₁(4月25日)、A₂(5月5日)、A₃(5月15日)、A₄(5月25日)和A₅(6月4日),5个播量处理，即B₁(18.0 kg/hm²)、B₂(22.5 kg/hm²)、B₃(27.0 kg/hm²)、B₄(31.5 kg/hm²)和B₅(36.0 kg/hm²)。结果表明：播期和播量对产量的影响均达到极显著水平；二者交互对产量、有效穗数、穗粒数、千粒重的影响均达到极显著水平。随着播期的推迟，直播稻产量先增加后减少。在A₁、A₂、A₃、A₄和A₅播...     

Kinetic study of austenite formation during continuous heating of unalloyed ductile iron

The austenite formation kinetics in unalloyed cast ductile iron was studied on the basis of dilatometry measurements, and Avrami's equation was used to estimate the material's kinetic parameters. A continuous heating transformation diagram was constructed using heating rates in the range of 0.06 to 0.83℃·s-1. As the heating rate was augmented, the critical temperatures, A_c1 and A_α, as well as the intercritical range, which was evaluated as the difference between the critical temperatures, ΔT=A_α - A_c1, increased. At a low heating rate, the kinetics of austenite formation was slow as a consequence of the iron's silicon content. The effect of heating rate on k and n, the kinetic parameters of Avrami's equation, was also determined. Parameter n, which is associated with nucleation sites and growth geometry, decreased with an increase in heating rate. In addition, parameter k increased with the increase of heating rate, suggesting that the nucleation and growth rates are carbon- and silicon-diffusion controlled during austenite formation under continuous heating.     

Investigation of nanocrystalline structure in selected carbonaceous materials

The structural parameters of nine Indian coals were determined by X-ray diffraction (XRD) and Raman spectroscopy. The study revealed that the coals contain crystalline carbon of turbostratic structure with amorphous carbon. The stacking height (L_c) and interlayer spacing (d₀₀₂) of the crystallite structure of the coals ranged from 1.986 to 2.373 nm and from 0.334 to 0.340 nm, respectively. The degree of graphitization was calculated to range from 42% to 99%, thereby confirming the ordering of the carbon layers with the increase in coal rank. An exponential correlation was observed among the aromaticity (f_a), the lateral size (L_a), and the rank (I₂₀/I₂₆), suggesting that the coal crystallites are nanocrystalline in nature. A very strong correlation was observed between the structural parameters (f_a, d₀₀₂, L_c, the H/C ratio, and I₂₀/I₂₆), the volatile matter content, and the elemental carbon content, indicating the structures of coals are controlled by the degree of contact metamorphism. The Raman spectra exhibited two prominent bands: the graphitic band (G) and the first-order characteristic defect band (D). The deconvolution resulted in five peaks: G, D1, D2, D3, and D4. The intense D1 band, which appeared at ~1350 cm?1, corresponds to a lattice vibration mode with A_1g symmetry. The D2 mode, which appeared at ~1610 cm?1, arises from the structural disorder as a shoulder on the G band.     

K(θ)上可解多项式代数中左Grobner基的计算

给定域K的单代数扩域K(θ)上可解多项式代数A=K(θ)［a₁,…,a_n］, 设A的子代数A₀=K［a₁,…,a_n］是K上可解多项式代数. 通过考察A与多项式代数A₀［x］之间的结构关系, 给出将A中左Grobner基的计算转换为A₀［x］中左Grobner基计算的有效方法.     

一类正则图的邻强边染色

研究一类正则图G(n,n,r)(n=1,2(mod 3))的邻强边染色. 用构造性方法给出了一类正则图的邻强边染色, 验证了对|V(G)|≥3的连通图G（V,E）(G(V,E)≠C₅), 有Δ(G)≤χ′_αs(G)≤Δ(G)+2成立.     

具有改善四环素降解活性的(GO/TiO2)N一维光子晶体光催化剂的设计

(GO/TiO₂)_N (GO represents graphene oxide, and N represents the period number of alternate superposition of two dielectrics) one-dimensional photonic crystal with different lattice constants was prepared via the sol–gel technique, and its transmission characteristics for photocatalysis were tested. The results show that the lattice constant, filling ratio, number of periodic layers, and incident angle had effects on the band gap. When the lattice constant, filling ratio, number of periodic layers, and incident angle were set to 125 nm, 0.45, 21, and 0°, respectively, a gap width of 53 nm appeared at the central wavelength (322 nm). The absorption peak of the photocatalyst at 357 nm overlapped the blue edge of the photonic band gap. A slow photon effect region above 96% reflectivity appeared. The degradation rate of tetracycline in (GO/TiO₂)_N photonic crystal was enhanced to 64% within 60 min. Meanwhile, the degradation efficiency of (GO/TiO₂)_N one-dimensional photonic crystal was effectively improved compared with those of the GO/TiO₂ composite film and GO/TiO₂ powder.     

Effect of magnesium addition on inclusions in H13 die steel

The effect of magnesium addition on the number, morphology, composition, size, and density of inclusions in H13 die steel was studied. The results show that the total oxygen content in the steel can be significantly decreased to 0.0008wt%. Al₂O₃ and MnS inclusions are changed into nearly spherical MgO·Al₂O₃ spinel and spherical MgO·MgS inclusions, respectively. The number of inclusions larger than 1 μm decreases and the number of inclusions smaller than 1 μm increases with increasing magnesium content. V(N,C) precipitates around MgO·Al₂O₃ and MgO·MgS inclusions during solidification of liquid steel. The densities of MgO·Al₂O₃ spinel inclusions are lower than that of alumina inclusions. With increasing magnesium content in the Mg-containing inclusions, the density of inclusions decreases, leading to the improvement of inclusion removal efficiency.     

Comparison of Ferrite Refinement Mechanisms by Different Processing Schedules in 08 and 20Mn Steels

The influence of deforming temperature on ferrite refinement was analyzed by comparing the microstructures obtained by deformation at above A_r3, in two-phase region of (α + γ) and at below A₁ in clean 08 and 20Mn steels. The results indicate that ferrite refinement through strain induced transformation by deformation at above A_r3 is more effective than that by deformation simply through ferrite dynamic recrystallization. The main problem of ferrite refinement by deformation at below A_r3 is the inhomogeneity of microstructure which is controlled by the orientations and sizes of ferrite grains and the distribution of second phases. Ferrite dynamic recrystallization after strain induced transformation can further effectively refine ferrite.     

Isothermal oxidation behavior and mechanism of a nickel-based superalloy at 1000℃

The oxidation behavior of a nickel-based superalloy at 1000℃ in air was investigated through X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy analysis. A series of oxides, including external oxide scales (Cr₂O₃, (TiO₂ + MnCr₂O₄)) and internal oxides (Al₂O₃,TiN), were formed on the surface or sub-surface of the substrate at 1000℃ in experimental still air. The oxidation resistance of the alloy was dependent on the stability of the surface oxide layer. The continuity and density of the protective Cr₂O₃ scale were affected by minor alloying elements such as Ti and Mn. The outermost oxide scale was composed of TiO₂ rutile and MnCr₂O₄ spinel, and the growth of TiO₂ particles was controlled by the outer diffusion of Ti ions through the pre-existing oxide layer. Severe internal oxidation occurred beneath the external oxide scale, consuming Al and Ti of the strength phase γ' (Ni₃(Al,Ti)) and thereby severely deteriorating the surface mechanical properties. The depth of the internal oxidation region was approximately 35 μm after exposure to experimental air at 1000℃ for 80 h.     

2×n格子图的弱罗马控制数

图G弱罗马控制数是图G的所有弱罗马控制数(WRDF)的最小权.本文运用指标函数法和比较函数法确定了2×n 格子图的弱罗马控制数.

Abstract：

The weak Roman domination number of G is the minimum weight of a weak Roman dominating function (WRDF) in G. In this paper, we determine the weak Roman domination number of 2 × n grid graphs.     

Preparation of Al-Cu-Fe-(Sn,Si) quasicrystalline bulks by laser multilayer cladding

(Al₆₅Cul₂₀Fe₁₅)_100-x Sn_x (x=0, 12, 20, 30) and Al₅₇Si₁₀Cu₁₈Fe₁₅ powders were cladded on a medium carbon steel (45# steel) substrate by laser multilayer cladding, respectively. The phases and properties of the produced quasicrystalline bulks were investigated. It was found that the main phases in the Al₆₅Cul₂₀Fe₁₅ sample were crystalline λ-Al₁₃Fe₄ and icosahedral quasicrystal together with a small volume fraction of θ-Al₂Cu phase. The volume fraction of icosahedral phase decreased as the Sn content in the (Al₆₅Cul₂₀Fe₁₅)_100-x Sn_x samples increased owing to the formation of β-CuSn phase. The increase of Sn content improved the brittleness of the quasicrystal samples. The morphology of the solidification microstructure in the Al₅₇Si₁₀Cu₁₈Fe₁₅ sample changed from elongated shape to spherical shape due to the addition of Si. The nanohardness of the laser multilayer cladded quasicrystal samples was equal to that of the as-cast sample prepared by vacuum quenching. In terms of hardness, the laser cladded Al₅₇Si₁₀Cu₁₈Fe₁₅ quasicrystalline alloy has the highest value among all the investigated samples.     

鄂尔多斯盆地富县地区延长组原油生物标志物特征及油源对比

 系统采集鄂尔多斯盆地南部中生界的烃源岩、富县地区延长组原油及油砂样品,对它们的饱和烃馏分进行GC-MS 分析,通过对生物标志物组成特征的研究探讨富县地区延长组原油的来源。结果表明:根据Pr/Ph,8β(H)-补身烷和C30重排藿烷相对含量,鄂尔多斯盆地南部中生界烃源岩可划分为A₁、A₂、A₃、A₄、B 类,富县地区延长组原油可划分为Ⅰ、Ⅱ、Ⅲ类,目前发现的原油主要是第Ⅰ类;第Ⅰ类原油来自A₁类烃源岩(深湖相沉积相带的长7 油页岩),第Ⅱ类原油来自A₂类烃源岩(深湖-半深湖沉积相带的长7 暗色泥岩),第Ⅲ类原油来自A₃类烃源岩(半深湖沉积相带的长7 暗色泥岩)。     

高阶线性微分方程亚纯解的增长性

利用亚纯函数值分布理论,研究了亚纯系数高阶线性微分方程f^(k)+A_k-1(z)f^(k-1)+…+A₀(z)f=0解的增长性,证明了如果A₀(z)以∞为亏值,A_j(z)(1≤j≤k-1)满足某些条件,则上述方程的每个非零亚纯解都为无穷级,得到解的超级的下界估计.