An Exchange Algorithm for the Best Chebyshev Normal Approximation by Quadratic Curves

According to the criterion of measuring profile error,a mathematical model for the best approximation to profile of gear is presented;the characteristic of the best quadratic curve approximation is derived.An algorithm and its convergence are discussed.Finally,the quadratic curve approximations to the profiles of many gears are obtained efficiently by the algorithm.The approximation errors are less than 0.8 micrometers.     

Analysis of diffusion equation based on steady state assumption：Ⅰ.the process of steady state approximation

The Fick diffusion equation is widely used to describe mass transfer in a particlea droplet or a liquid layer in a chemical reactorwhere the definition domain of the diffusive equation is limitedbecause it is decided by the scale of those particles or droplets.The diffusive equation with a definition domain of certain length has no analytic solutions unless the series solution.Soto obtain approximate solutions of a diffusive equation is of theoretical and practical significance.After an assumption of constant concentration variance ratio is made and substituted for the presumption of constant concentration frequently used in kinetics of multi-phase reactiona detail process to deal with diffusion equation based on steady state approximation is givenand the approximate solutions of the diffusive equation with the second boundary condition and the third boundary condition are obtained in the meantime.The method to deal with diffusion equation by steady state approximation may be applied to many fields in engineering.     

Small scale wind tunnel for high pressure and high energy discharge

A kind of small scale wind tunnel with low velocity is proposed according to the characteristics of strong ionization discharge chamber and the demands of discharge for flux, velocity and flow fields. On the precondition that the airflow field and velocity is satisfied, aerodynamic design and structural design are carried out. Key techniques are studied including overall structure, aerodynamic and structural design of airflow vent and collection vent, aerodynamic and structural design of power section, flow rate adjustment and control, and cooling system of motor. Based on the design scheme, a small scale wind tunnel with strong ionization discharge for an enterprise is developed. Application indicates that the small scale wind tunnel is a practical and effective airflow loop device for high pressure and strong ionization discharge with the features of stability and reliability.     

Density Functional Theory on the Reaction of Hydroquinone with Dimethyl Sulfate and Synthesis in Lab

DFT/B3LYP calculations at 6-31G(d,p) basis set level and Tomas's PCM model and carried out for optimize the reactant and intermediate and production which is the reaction of Hydroquinone with Dimethyl Sulfate.Then(It's) single energy and charge density.According to calculatms result,to the best reaction condition is chosen,the rate of 4-methoxyphenol and 1,4-Dimethoxybenzene is limited to 1:0.16.     

Theoretical Study of Electronic Structure and Hardness of Spinel-CSi2N4 Compounds

The electronic structure and elastic properties of ground state spinel-CSi2N4 are investigated using pseudopotential plane-wave method with the general gradient approximation to the density functional theory. The geometric structures of spinel-CSi2N4 is firstly optimized to obtain the most stable state with the lowest energy and the lattice parameters, then the total energy, elastic constants, bulk modulus, band structure and density of states are calculated and analyzed, and finally, the hardness of the compounds are calculated and compared with spinel-C3N4.     

A Simplified Thermoelastic Model for Composite Iaminated Shells

To effectively analyze the one way coupled thermoelastic problem for composite laminated shells, a simplified thermoelastic shell model based on the variational asymptotic method (VAM) was developed. The 3 D energy functional for composite laminated shell was established according to the Hamilton extended principle. Then the 3 D energy was asymptotic expanded into a series of 2 D approximation energies by taking advantage of the inherent small parameters. Finally, the approximate energy was converted to the form of Reissner Mindlin model, and the 3 D recovery relationships were deduced to accurately predict the 3 D field distribution along the thickness direction. The cylindrical bending example of a four layer composite laminated shells under the sinusoidal surface load and temperature field shows that the modeling speed is fast (equivalent single layer model, which can reduce two or three order calculations compared to the 3 D finite element method), and the nonlinear approximation ability is excellent (convergent to the exact solution).     

VARIABLE METRIC METHODS WITH OPTIMUM DIFFERENCE APPROXIMATIONS OF DERIVATIVES

On the basis of the relation between truncation and rounding errors of difference approximation, the interval formula which can minimize the total error is founded. The method choosing optimum interval is applied to unconstrained VMM(Variable Metric Method), SUMT-DFP, and constrained VMM. Three optimization methods with optimum difference approximations are presented. These methods are very efficient, especially when dealing with complex problem functions.     

Density Functional Theory Compute on Electronegativities to Superconductivity of Oxides

In this article we have worked out the correlation between electronegativity and high temperature superconductivity for oxide. It is suggested the equalized electronegativity, X cq , can be used as a empirical criterion for superconductivities of oxides. For determining the X cq , a new formula for the calculation of X cq values has been obtained The X cq values of 230 oxide superconductors have been calculated. The result shows that the X cq values of all the oxide superconductors concentrate in a narrow range from 5.00 to 5.63 and that the oxides with values out side this region would be non-superconductive. This criterion can be applied to almost all the oxide superconductors. It is clearly that this result is able to benefit further inquiries about the mechanism of superconductivity.     

棉花适宜密度与播种量设计的动态知识模型

通过分析和提炼有关棉花种植密度与播种量的最新研究资料,在综合量化气候条件、土壤类型、产量目标、管理水平和品种特性等影响因子的基础上,建立了具有时空适应性的棉花种植密度和播种量设计动态知识模型,可用于精确定量不同环境和不同产量目标下的种植密度和播种量。利用不同生态点、不同品种、不同土壤类型和不同产量目标等资料对知识模型进行了验证,结果表明模型具有较好的决策性和适用性。     

密度对棉花产量及棉铃内部产量构成的影响

以杂交种中棉所75和常规种鲁棉研28为材料,从冠层、单株以及单铃内部几个不同层次深入研究了密度对产量及产量构成因子的影响。结果表明,密度显著影响棉花产量,且这种影响可追溯到单株,甚至单个棉铃内部的单个种子上。5.1万株和8.7万株·hm-2密度下皮棉产量无显著差异,但显著高于1.5万株·hm-2密度的产量。在该试验密度范围,随着密度增加,棉株上部果枝和外围果节的成铃率显著降低;铃重、单粒种子截面积和单铃内种子数随密度增加呈下降趋势;单粒种子上纤维质量与种子所处位置相关,在棉铃基部和中部其随密度变化差异较大。     

Mechanism of Photocatalytic Activity of TiO2 Doped by Fe(III)

Ti_(4)O_(8) super cell are formated and geometry optimized.The band gap, Fermi level, density of states of TiO_(2) doped by Fe(III) have been simulated with relativistic density functional theory and Plane Wave Pseudo Potentials (PWPP). The band gap of TiO_(2) doped by Fe(III) become narrow, and density of states are enhanced. It can decrease composition of e~(-) and h~(+), Photocatalytic activity of TiO_(2) are enhanced by doped Fe(III).     

稻田免耕年限与复耕次数对土壤容重和水稻生长的影响

试验以免耕1~10年稻田和免耕3~6年后复耕1次、复耕2次、复耕3次稻田为对象,探索不同免耕年限与复耕次数对稻田土壤容重和水稻生长的影响,以期为因地制宜推广免耕技术提供科学依据。结果表明：无论土壤表层还是下层,免耕土壤容重总是大于翻耕土壤,且随着免耕时间的延长,其土壤容重逐渐加重,免耕3年及以后处理土壤容重显著大于翻耕处理(P<0.05),随着复耕次数的增加,土壤容重逐渐降低。连续免耕1~5年的田块,免耕栽培处理水稻最高苗和有效穗以及产量均表现为比翻耕栽培处理高,免耕6年处理表现相对平缓稳定,免耕7年及以后分蘖能力和产量明显下降。免耕3~5年后进行复耕处理水稻分蘖能力和产量总是低于对应的免耕4~6年处理,且随着复耕次数的增加差距逐渐扩大,免耕7年处理水稻分蘖能力和产量与免耕6年后进行复耕1次处理基本持平。结论为稻田免耕应以6年内为宜,当稻田连续免耕超过最适年限后,需要进行复耕作业,复耕1次即可。     

密度对棉花株间小气候、农艺性状及产量的影响

为掌握棉花群体结构中的小气候环境状况,确定棉花不同密度对产量的影响,设计6个不同密度测定农艺性状,选择棉花郁闭度最大的开花盛期,测定不同棉花密度群体田间小气候要素。结果表明,密度不同棉花的农业性状发生很大变化,群体间光、温、湿度等气候因子有较大的改变。随着密度的增加,棉花株高、茎粗、叶片数、果枝数、蕾数、铃数、铃重与株间梯度温度差呈显著负相关,而与透光率呈正相关;最佳密度群体株间梯度温度差应0.3~0.4℃;棉株间地面透光率应在5.5%以上。密度22.5万株/hm²产量表现最佳,其次是27.0万株/hm²,再其次是18.0万株/hm²。在当前栽培管理水平下,北疆早熟棉花品种的种植密度以20万~25万株/hm²为宜。     

On the Variability of Harvest Indices

The harvest index Z is defined, for example for cereals, as the ratio between grain yield X and biological yield Y: Z = X/Y. For many purposes the variance of Z is of major interest. In this paper several approximations for this variance are derived and their accuracy was investigated. These explicit formulae depend on some characteristics (means, variances or coefficients of variation, covariances or correlations) of the component variables grain yield X and biological yield Y. It is shown that for most practical applications the approximation v²z = v²x + v²y - 2rv_xv_y provides a sufficient accuracy for numerical calculations (v_x v_y and v_z are the coefficients of variation for grain yield X, biological yield Y and harvest index Z and r denotes the correlation coefficient between X and Y). Some conclusions on the relations between v_x, v_y and v_z are derived.
Finally, all the theoretical investigations and results are demonstrated and applied to a numerical example of winter-rapeseed data.     

不同生态条件下‘中地77’对密度和施肥量的反应

通过研究‘中地77’对密度和施肥量的反应,旨在进一步挖掘该品种在辽宁省的生产潜力,为其大面积生产提供参考。试验采用裂裂区设计,肥料为主区,密度为副区,品种为副副区。肥料处理设常量施肥、高量施肥2个水平。密度设5个水平,即45000、52500、60000、67500、75000株/hm²。随机区组设计,3次重复。结果表明：‘中地77’的耐密性较强,密度为60000株/hm²产量最高;不同地区相比,辽北地区产量较高,平均比辽西高25.6%;在辽西地区,增加施肥量有明显的增产效果,最高可增产28.8%,而在辽北地区,增加施肥则无明显的增产效果。综合考虑肥料和密度因子。辽西地区：高量施肥条件下,密度为60000株/hm²产量最高(8867.5 kg/hm²);辽北地区：常量施肥条件下,密度为60000株/hm²产量最高(9908.8 kg/hm²)。     

林业区划在森林火险天气等级预报中的应用

为进一步提高森林火险等级预报服务并为全国森林火险预报提供新观点,结合森林火险天气等级和林业区划调查构建了内蒙古森林火险评定方法。此方法改变了以往只以火险天气等级为森林火险依据的单一性,通过添加树种燃烧组成、农业人口密度、路网密度及防火期气象要素等,完成了气象要素与下垫面森林资源的完美结合,实现火险天气等级在林业区划上的再分配。研究结果表明,内蒙古林业区划Ⅲ级区应该在实际森林火险预报中上升1个等级,Ⅰ级区应降低1个等级,在没有森林资源分布和结合的地区应降低2个等级。     

NaCl和KCl溶液康普顿散射的影响因素

自康普顿散射提出以来,其理论研究和应用研究一直是国内外的热点。基于NaCl和KCl溶液的康普顿散射,通过一定的近似处理,从理论上分析适合这两种溶液的康普顿散射光子数与溶液浓度之间的关系表达式;然后,通过康普顿散射实验验证康普顿散射的理论和实验研究。为了从更微观的角度来把握NaCl和KCl溶液康普顿散射的机理,笔者立足于密度泛函理论对NaCl与KCl溶液的电子结构作了深入分析,得出结论:除质量密度、散射衰减因子以及溶液的浓度外,电子数密度和电子受到的束缚也对康普顿散射光子数有影响,其中,电子数密度是影响NaCl与KCl溶液康普顿散射光子数的主要因素。     

宁夏中部干旱带特色产业发展现状与对策

近年来,宁夏中部干旱带特色产业规模不断扩大,市场不断扩展,营销网络逐步建立,发展势头强劲,已经成为当地农民增收的支柱产业。但是,尚存在着水资源严重短缺,产业化经营的规模小、层次低,龙头带动力较弱,产业链条未形成,合作经济组织不健全、科技服务体系不适应等问题。针对存在问题,提出了加大水利基础设施建设、增加投入、扩大规模、壮大龙头、创建品牌、搞活流通、依靠科技、提高效益等对策措施。     

不同密度对玉米‘郑单2098’产量及构成因素的影响

为研究密度对玉米‘郑单2098’产量及其构成因素的影响,探讨不同肥力水平下‘郑单2098’的最佳栽培密度。以‘郑单2098’为材料,在河南省西华和长葛两地研究了不同地力、不同密度对‘郑单2098’产量及相关性状的影响。结果表明：随着密度增加,产量先增后减,株高、穗位高、空秆率、秃尖增加,穗长、穗粗、行粒数、双穗率、穗粒重、百粒重减少,出籽率相对稳定;‘郑单2098’在中肥力水平下,随着密度的增加影响产量主要因素是穗行数和秃尖,而在高肥力水平下,随着密度的增加影响产量主要因素是穗粒重和百粒重。‘郑单2098’在中肥力水平下,适宜种植密度为5.25万株/hm²左右;在高肥力水平下适宜种植密度为6.75万株/hm²左右。     

THE APPLICATION OF FINITE - ELEMENT METHODS FOR THE ANALYSIS OF GALLBLADDER BILE FLOW IN VIVO

The transient flow fields of gallgladder bile in vivo are calculated by finite element methods. Computer tomograph, ultrasound B and contrast radiography are applied to determine the moving boundary conditions, The penalty formulation and moving triangle elements have been successfully adopted and be flow fields for axisymmetric Newtonian bile flow have been obtained. The results show that there exists obvions reverse flow at the cross section (Perpendicular to Center axis) and thus forms axisymmetric vartexes inside a contracting gallbladder in vivo,Which well agree with the previous prediction.