The Analytical Expressions for Computing the Minimum Distance between a Point and a Torus

In this paper, we present the analytical expressions for computing the minimum distance between a point and a torus, which is called the orthogonal projection point problem. If the test point is on the outside of the torus and the test point is at the center axis of the torus, we present that the orthogonal projection point set is a circle perpendicular to the center axis of the torus;if not, the analytical expression for the orthogonal projection point problem is also given. Furthermore, if the test point is in the inside of the torus, we also give the corresponding analytical expression for orthogonal projection point for two cases.

Electric gating of the multichannel conduction in LaAlO_(3)/SrTiO_(3) superlattices

The electric gating on the transport properties of two-dimensional electron gas(2DEG) at the interface of LaAlO_(3)/SrTiO_(3)(LAO/STO) heterostructure has attracted great research interest due to its potential application in fieldeffect devices. Most of previous works of gate effect were focused on the LAO/STO heterostructure containing only one conductive interface. Here, we systematically investigated the gate effect on high-quality LAO/STO superlattices(SLs)fabricated on the TiO_(2)-terminated(001) STO substrates. In addition to the good metallicity of all SLs, we found that there are two types of charge carriers, the majority carriers and the minority carriers, coexisting in the SLs. The sheet resistance of the SLs with a fixed thickness of the LAO layer increases monotonically as the thickness of the STO layer increases. This is derived from the dependence of the minority carrier density on the thickness of STO. Unlike the LAO/STO heterostructure in which minority and majority carriers are simultaneously modulated by the gate effect, the minority carriers in the SLs can be tuned more significantly by the electric gating while the density of majority carriers is almost invariable. Thus, we consider that the minority carriers may mainly exist in the first interface near the STO substrate that is more sensitive to the back-gate voltage, and the majority carriers exist in the post-deposited STO layers. The SL structure provides the space separation for the multichannel conduction in the 2 DEG, which opens an avenue for the design of field-effect devices based on LAO/STO heterostructure.

The determination of 52 elements in marine geological samples by an inductively coupled plasma optical emission spectrometry and an inductively coupled plasma mass spectrometry with a high-pressure closed digestion method

An improved analytical method to determine the content of 52 major, minor and trace elements in marine geological samples, using a HF-HCl-HNO_3 acid system with a high-pressure closed digestion method（HPCD）, is studied by an inductively coupled plasma optical emission spectrometry（ICP-OES） and an inductively coupled plasma mass spectrometry（ICP-MS）. The operating parameters of the instruments are optimized, and the optimal analytical parameters are determined. The influences of optical spectrum and mass spectrum interferences, digestion methods and acid systems on the analytical results are investigated. The optimal spectral lines and isotopes are chosen, and internal standard element of rhodium is selected to compensate for matrix effects and analytical signals drifting. Compared with the methods of an electric heating plate digestion and a microwave digestion, a high-pressure closed digestion method is optimized with less acid, complete digestion,less damage for digestion process. The marine geological samples are dissolved completely by a HF-HCl-HNO_3 system, the relative error（RE） for the analytical results are all less than 6.0%. The method detection limits are 2–40μg/g by the ICP-OES, and 6–80 ng/g by ICP-MS. The methods are used to determine the marine sediment reference materials（GBW07309, GBW07311, GBW07313）, rock reference materials（GBW07103, GBW07104,GBW07105）, and cobalt-rich crust reference materials（GBW07337, GBW07338, GBW07339）, the obtained analytical results are in agreement with the certified values, and both of the relative standard deviation（RSD） and the relative error（RE） are less than 6.0%. The analytical method meets the requirements for determining 52 elements contents of bulk marine geological samples.

ON THE CONSTRUCTION OF MAJOR AND MINOR FUNCTIONS

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基于拟合椭圆的等震线长短轴测量方法

提出了一种改进的拟合椭圆算法用于测量等震线长短轴,即将等震线测量的模式和直接测量算法的概念以约束的形式加入拟合椭圆算法,并使用最小二乘法求解椭圆系数,在与传统等震线测量方法保持一致的基础上,减少了直接测量方法的主观不确定性。在此基础上讨论了拟合椭圆算法的适用性和鲁棒性,将等震线长短轴的测量结果与前人的结果进行了对比。结果表明:拟合椭圆算法的适用性较好,可用于等震线的拟合;拟合椭圆算法的鲁棒性较好,计算结果较为稳定;对于未闭合且形状复杂的等震线,计算结果相对离散,要单独验证结果是否合理;利用拟合椭圆算法得到的等震线长短轴结果与前人的结果较为一致,可用于建立烈度衰减关系。

2015年羽毛球比赛林丹路线及落点“Pareto”研究

采用文献资料法、数理统计法、录像观察等方法对2015年羽毛球男单比赛中林丹半决赛时球的路线和球的落点进行主次区域研究。结果显示:林丹主要攻击对手区域有b1区、a2区、a1区、a3区、b3区和b2区;在前区向对手后区攻击次数最多,在中区和后区向对手中区攻击次数最多;向对手b1区攻击次数最多,向b6区攻击次数最少。

基于就业现实的高校“小语种+”专业课程设置探析

近年来小语种专业毕业生在就业问题上的压力日益增加,已涉及学生的择业范围、转行难度等。因此,为了适应时代需求,相关高校可以积极探索“小语种+”的课程设置模式,将小语种同其他专业课程相结合,丰富学生的知识结构,帮助其在择业时拓宽范围,更好地为社会培养复合型人才。

大单元视角下“细胞核的结构和功能”教学设计

以“细胞核的结构和功能”为例,在大单元视角下,以重要概念为单元教学主题,以相关的次位概念为课时教学主题,选择主线式情境,帮助学生建构合理的知识框架,提升学生解决问题的能力,发展学生的学科核心素养。

熔融制样X射线荧光光谱法快速测定铌精矿中10种元素

采用高温熔融制样方式将铌精矿制备成均匀稳定的玻璃片,利用X射线荧光光谱法测定铌精矿中铌、硅、钙、镁、钛、磷、锶、锰、钡、钍10种元素的含量。将样品与四硼酸锂-偏硼酸锂混合溶剂(质量比67∶33)按照1∶14的质量比混合,加入30 g/L溴化锂溶液0.2 mL,在全自动熔样机上于1050℃熔融8 min,摇摆6 min,静置冷却脱模后得到测定玻璃样片。采用人工配制标准样品的方法建立标准工作曲线,以经验系数法校正谱线重叠效应,用理论α系数法校正基体效应,两个不同含量水平铌精矿样品测定结果的相对标准偏差为0.23%~3.91%(n=9),该方法与化学法测定值基本一致。该方法可实现实际铌精矿样品中10种主次量元素的快速批量日常检测。

新农科背景下桑蚕人才培养体系构建——河池学院微辅修专业实例分析

蚕桑产业是广西的支柱和特色优势产业,为现代农业发展作出了重要贡献,但目前仍然存在产业人才紧缺、地方高校人才培养没有真正落实到位等问题。文章通过分析河池学院前期桑蚕人才培养存在的问题及原因,阐述了桑蚕实用型人才培养新模式——现代桑蚕关键技术微辅修专业的具体做法及成效,对新农科背景下培养地方产业紧缺人才、解决毕业生就业压力等问题具有极为重要的意义,也为兄弟院校培养地方产业紧缺人才提供借鉴和指导。

Majorization Results and Coefficients Bounds for a Class of Univalent Functions Associated with Operator

In this paper we introduce a new general subclass n,G∑ a,λ(A, B, α) of univalent functions related the known integral operator and differential operator. Some majorization results for n,G∑ a,λ(A, B, 1) as well as the other functions are given. Furthermore, we find the coefficients bounds on |a_2| and |a_3| for functions in*n,G∑ a,λ(A_1, B_1, A_2, B_2, α_1, α_2), which is the bi-univalent functions defined by n,G ∑a,λ(A, B, α) and subordination. By giving specific values of the parameters of our main results, several(known or new) consequences of main results are also discussed.

Genetic Analysis of Major and Minor Gene(s) Resistant to Stripe Rust in Important Resource Wheat Line Jinghe891-1

Inheritance of line Jinghe891-l resistant to pathotype of Puccinia striiformis in two patterns of temperature (Normal: day 18℃ /night 10℃ , High: day 24℃ /night 15℃ )was studied in this paper. The results showed that there were at least two pairs of dominant major genes and one pair of recessive minor genes in Jinghe 891-1. The two pairs of major genes that conferred resistance to CY31 were allelic or linked closely with resistance gene in Jubilejna Ⅱ , Kangyin655 and T. spelta Album. They were novel resistance genes and were inherited in a repeated or independent mode. The minor genes, which could modify the major genes, were sensitive to temperature and conferred resistance to all pathotypes of Puccinia striiformis in China. It is recommended that this line can be used as an important resource stock.

长江中游典型顺直分汊河段冲刷调整的特性与机理

与单一分汊河段相比,连续分汊河段的上游和下游汊道段相互影响,主支汊冲刷调整更加复杂。基于实测资料分析了长江中游武汉河段白沙洲-潜洲连续顺直分汊段冲刷调整的特性与机理。分析结果表明:三峡水库蓄水后两汊道河段的主支汊深泓纵剖面均冲刷下降,断面向窄深发展,江心洲的洲体冲刷萎缩;白沙洲主汊冲刷快于支汊。潜洲支汊冲刷快于主汊,支汊分流比增加。两汊道段的相关性导致白沙洲主汊深泓的右摆增强了潜洲支汊的分流比和冲刷动力,减小了潜洲主汊的分流比和冲刷动力,同时潜洲支汊河床的抗冲性弱于主汊,白沙洲主汊的抗冲性弱于支汊,两方面因素共同导致了两汊道段主支汊不同的冲刷发展过程。

Analysis on Major Selection and Employment Situation of Minority Students

In recent years,due to the impact of university increase enrollment policy,the slowdown of global economic growth and other factors,the Students face employment pressure has become a general social problem.And minority university students have a huge disadvantage in employment direction compared with the other ordinary university students.Exploring the ways of minority university students'employability and major selection capability are helpful to find targeted solutions and it has impor tant practical value.

Mechanical analysis of folds in compressive belt and its significance to earthquakes

The paper proposes the conception of Beads type fold system. The mechanical analyses of the typical tectonic system are made by means of elastic stability theory, mathematical and mechanical method and rheology. The relation among the deflections of folds and time, external forces, and distribution of stresses, strain energy density are analyzed to explain the causing mechanism of folding earthquake.

An Analysis of English Learning Motivation of Minority Students in Higher Vocational School

This paper analyzes the English learning motivation of minority students of non-English major.Minority students are a unique community in the higher vocational school because of their special background and psychology.It is essential for teachers to understand their motivation of learning English so as to save time and teach more efficiently.

Application of Stochastic Fracture Network with Numerical Fluid Flow Simulations to Groundwater Flow Modeling in Fractured Rocks

The continuum approach in fluid flow modeling is generally applied to porous geological media, but has limited applicability to fractured rocks. With the presence of a discrete fracture network relatively sparsely distributed in the matrix, it may be difficult or erroneous to use a porous medium fluid flow model with continuum assumptions to describe the fluid flow in fractured rocks at small or even large field scales. A discrete fracture fluid flow approach incorporating a stochastic fracture network with numerical fluid flow simulations could have the capability of capturing fluid flow behaviors such as inhomogeneity and anisotropy while reflecting the changes of hydraulic features at different scales. Moreover, this approach can be implemented to estimate the size of the representative elementary volume (REV) in order to find out the scales at which a porous medium flow model could be applied, and then to determine the hydraulic conductivity tensor for fractured rocks. The following topics are focused on in this study: (a) conceptual discrete fracture fluid flow modeling incorporating a stochastic fracture network with numerical flow simulations; (b) estimation of REV and hydraulic conductivity tensor for fractured rocks utilizing a stochastic fracture network with numerical fluid flow simulations; (c) investigation of the effect of fracture orientation and density on the hydraulic conductivity and REV by implementing a stochastic fracture network with numerical fluid flow simulations, and (d) fluid flow conceptual models accounting for major and minor fractures in the 2 D or 3 D flow fields incorporating a stochastic fracture network with numerical fluid flow simulations.

椭圆截面弹体侵彻性能的影响因素分析

为研究截面形状和头部曲径比对椭圆截面弹体侵彻性能的影响,开展了圆锥和椭圆锥压头的静态压痕试验,获得了不同截面压头缓慢贯入材料时的力-位移曲线。随后,基于30 mm弹道炮平台,开展了3种不同椭圆截面弹体在400~800 m/s撞击速度范围内正侵彻2A12厚铝靶试验,获得了靶体的破坏形貌及弹体侵彻深度。基于空腔膨胀模型及阻力函数修正系数,建立了椭圆截面弹体侵彻金属厚靶侵彻动力学模型,结合试验结果验证了模型的有效性,并系统分析了弹体截面形状和头部曲径比对侵彻性能的影响。研究结果表明,与圆锥压头相比,具有相同截面面积的椭圆锥压头贯入材料时阻力更大,当压头的截面长短轴比从1.00增大至2.00时,贯入阻力增大10.1%。当弹体截面面积相当,且各横截面保持长短轴比不变时,椭圆截面弹体的长短轴比越大,其侵彻性能越差;椭圆截面弹体侵彻性能随着截面长短轴比的增大和头部曲径比的减小而降低。

三维变形管内降膜蒸发特性

为了提高降膜蒸发器的传热性能,将三维变形管用于MVR降膜蒸发器中,利用FLUENT软件探究了管内液膜的分布特点,分析了长、短轴比对三维变形管的传热性能的影响。结果表明:相比圆管,三维变形管内液膜的厚度会逐渐减小,流体速度场与温度场的协同性相对来说也更好;随着长、短轴比的增大,三维变形管内液膜的厚度会逐渐减小,液膜速度更为缓慢,而且进一步提高了速度场与温度场的协同性,还增强了液膜的扰动性,最终努塞尔数从0.249提高到0.276。将三维变形管应用于MVR蒸发器中,具有良好的换热效果,可节省换热材料。

熔融制样-X射线荧光光谱法测定红土型铝土矿中主次量组分

铝土矿中主次量组分的准确测定对其资源综合利用具有重要意义。熔融制样-X射线荧光光谱法已广泛应用于铝土矿中主次量组分的测定中。而马达加斯加红土型铝土矿基体与常用的铝土矿标准物质有很大的不同,现有的标准物质不能满足该类型铝土矿主次量组分的测定需要。将部分铝土矿标准物质分别与锆矿石标准物质、氧化铁基准物质混合,制成校准样片,加入校准系列,扩大了氧化锆和氧化铁的测定范围,建立了熔融制样-波长色散X射线荧光光谱法测定马达加斯加红土型铝土矿中主次量元素的方法。对该样品的熔融方法进行了研究,对基体干扰的校正进行了探索,实现了对铝土矿中SiO_(2)、Al_(2)O_(3)、Fe_(2)O_(3)、TiO_(2)、CaO、MgO、K_(2)O、Na_(2)O、MnO、P_(2)O_(5)、ZrO_(2)、Ga_(2)O_(3)、V_(2)O_(5)、Cr_(2)O_(3)共14种组分的快速准确测定。将实验方法应用于其他铝土矿标准物质中主次量组分的测定,结果的相对误差(RE)为-8.64%~8.33%,相对标准偏差(RSD,n=12)不大于9.2%。采用实验方法对马达加斯加红土型铝土矿样品进行测定,测定结果的相对标准偏差(n=6)不大于7.4%,测定值和其他分析方法的结果进行了比对,结果一致。