曲线

Geodesic curvature of the pitch curve on spherical surface was introduced as a medium,through which the pitch curve on spherical surface can be changed into equivalent planar pitch curve by numerical computation method.

以曲面上曲线的短程曲率为媒介，导出了球面节曲线伸展成平面当量节曲线的算法。

Results indicate that:(1) by using HANTS, the researchers could get the EVI/NDVI harmonic curves, the mean VIs and the amplitude of the harmonics which then were utilized in the identification of the cultivated land, and EVI appeared to be more precise, with the overall accuracies of 97.17% and 95.99% and Kappa coefficients of 0.7938 and 0.6518, respectively.(2) Multiple cropping index was extracted by counting the number of the curve's peak; and when the threshold of the peak value of the NDVI and EVI curves were set as 0.25 and 0.20, respectively, the fallow land could be well figured out.(3) From harmonic curves, some eigenvalues, such as time of the maximum growth rate, time of peak and the value of peak can be extracted, based on which the crop types can be primarily distinguished. And EVI still performed better than NDVI in this section.

结果显示：（1）利用傅立叶谐波变换得到的EVI和NDVI时间谱曲线的谐波余项及谐波振幅对耕地进行识别，从识别精度来看，EVI要优于NDVI，识别精度分别为97.17%和 95.99%，Kappa系数分别达到0.7938和0.6518；（2）通过计算时间序列曲线的波峰数能够提取耕地的复种指数，并且在EVI和NDVI曲线波峰阈值分别设为0.20和0.25时，休耕地能较为准确地被识别出来；（3）通过提取作物生长期内曲线的VI最大增长速率时间点以及峰值时间点等信息，作物种类能被初步识别，并且EVI较NDVI具有更强的识别能力。

In this paper, based on the vector analysis and the warping torsion theory of curved thin-walled girders, a set of governing differential equations for the non-uniform torsion of thinwalled spatial helicoid girders is developed.

本文应用矢量运算及薄壁曲线梁翘曲扭转理论，建立了空间螺旋形的薄壁曲线梁基本微分方程，用初参数法解出翘曲扭转微分方程，为进一步进行薄壁螺旋曲线梁的空间结构分析提供理论基础。

The study shows that the pressure transient curve of fractured wells in closed circular formation can be divided into six different flow regimes. In condition of the same fracture opening width and fracture length, compared to rectangular fracture, the pressure drop with tapered fracture is bigger, and the dimensionless pressure and pressure derivative curves are higher. In condition of the same fracture opening permeability, compared to linear declining and constant conductivity fractures, the pressure drop with exponential declining conductivity fracture is the biggest, and the dimensionless pressure and pressure derivative curves are the highest.

研究结果表明：圆形封闭地层压裂井的压力动态曲线可以划分为6个流动阶段；在相同裂缝开口宽度和相同裂缝长度的条件下，与矩形裂缝相比，楔形裂缝压力消耗大，表现为无因次压力及压力导数曲线越高；在相同裂缝开口渗透率的条件下，与导流能力呈线性降低的裂缝以及常导流能力裂缝相比，导流能力呈幂指数降低的裂缝压力消耗最大，表现为无因次压力及压力导数曲线最高。

This bicubic Pythagorean hodograph curves can deal with the inflexion flexibly and two cubic Pythagorean hodograph curves reaches C 1 continuous at the connection point.

引 言PH曲线是一类特殊的平面多项式曲线，1 990年由 Farouki和 Sakkalis[1]在研究等距曲线的过程中提出。

By using complex analysis in representing parametric curves to avoid the complicated representation and fuzzy calculation, the cubic couple of Pythagorean hodograph is constructed, which satisfies C 1 Hermite interpolation conditions.

相应的两条 Bézier曲线表示及其控制顶点的计算简单方便。所得 4条插值曲线中，通常有 1条曲线具有很好的几何形状特征。结果可直接应用于各工业产品设计及加工领域中。

The effects of levulinic concentration and flow rate of hydrolyzate as well as column height were examined. Hydrochloric acid was used as eluent and the effect of concentration and flow rate on the elution of levulinic acid was evaluated.

在此基础上，直接利用小麦秸杆水解液研究了在装有D301树脂的固定床上的穿透曲线和洗脱曲线，考察了进样浓度、空速和树脂装柱高度对穿透曲线的影响。

Compared with Elliptic Curve Cryptosystems, Hyperelliptic Curve Cryptosystems has obvious security advantages , therefore the theory of HCC has caused the crypto circle's extensive attention in recent years.

与椭圆曲线密码体制相比，超椭圆曲线密码体制具有明显的安全性优势，因而，近几年来超椭圆曲线密码理论备受密码学界的重视。

In order to refine a method for defence against at least one attack made by means of differential power analysis on at least one hyperelliptic cryptosystem, in particular at least one hyperelliptic public key cryptosystem, which is given by at least one hyperelliptic curve of any genus over a finite field in a first group, where the hyperelliptic curve is given by at least one co-efficient, so that an essential contribution can be made towards an efficient and secure implementation of the hyperelliptic cryptosystem, it is proposed that the hyperelliptic curve and/or at least one element of the first group, in particular at least one in particular reduced divisor and/or at least one intermediate result of a scalar multiplication, is randomised.

为了改进用于防御在至少一个超椭圆密码系统中、特别是在至少一个超椭圆公共密钥密码系统中通过微分功率分析作出的至少一个攻击的方法，该超椭圆公共密钥密码系统是通过在第一组中有限域中任何种类的至少一个超椭圆曲线给出的，其中超椭圆曲线由至少一个系数给出，以使得可以对于超椭圆密码系统的有效而安全的实施方案作出重要的贡献，提出将超椭圆曲线和/或第一组的至少一个元素、特别是至少一个特定的减小的除数和/或标量乘法的至少一个中间结果进行随机化。

In 1989, Neal Koblitz proposed the hyperelliptic curve cryptosystems as a natural generalization of ECC. HCC is based on the discrete logarithm problem on the Jacobian of hyperelliptic curves over finite fields.

作为椭圆曲线的一个推广，Neal Koblitz在1989年提出了超椭圆曲线密码体制，它是基于有限域上超椭圆曲线的Jacobian上的离散对数问题。D。

I will endeavour to find you some assistance.

我尽力帮你找人帮忙。

At first I only know bruck is the idol of American younglings, afterwards I returned back to Taiwan ,even in Beijing last year ,I saw her poster everywhere, I was so surprised at her charm.

起初我只晓得布鲁克雷德丝是美国少男少女崇拜的偶像，后来回台湾，甚至去年在北京，居然也四处看见她的海报，才惊讶她的魅力之大。