从乙烯与丙烯酸二茂铁甲酰氧基乙酯共聚物制备碳纳米材料

使用乙烯和丙烯酸二茂铁甲酰氧基乙酯(FcEA)为单体,合成了乙烯与丙烯酸二茂铁基乙酯共聚物[P(E-co-FcEA)].以P(E-co-FcEA)作为前驱体,通过改变裂解条件,自催化制得系列碳纳米材料.     

Single phase encoding method based on the fractional Fourier transform

We propose a single phase encoding scheme for encrypting image by using fractional Fourier transform. Single phase mask is designed in order to be symmetrical about certain direction, which can be used in the process of both encryption and decryption. A conjugate mask is not required in the image decryption process, which is very convenient for the practical application in optics. Moreover, the optical implementation of the image encryption and decryption is given. The implementing structure is composed of lens and spherical mirror. Numerical simulations have demonstrated the validity and security of the encryption algorithm.     

Measurement of thermal expansion coefficient of nonuniform temperature specimen

A new technique is developed to measure the longitudinal thermal expansion coefficient of C/C composite material at high temperature. The measuring principle and components of the apparatus are described in detail. The calculation method is derived from the temperature dependence of the thermal expansion coefficient. The apparatus mainly consists of a high temperature environmental chamber, a power circuit of heating, two high-speed pyrometers, and a laser scanning system. A long solid specimen is resistively heated to a steady high-temperature state by a steady electrical current. The temperature profile of the specimen surface is not uniform because of the thermal conduction and radiation. The temperature profile and the total expansion are measured with a high-speed scanning pyrometer and a laser slit scanning measuring system, respectively. The thermal expansion coefficient in a wide temperature range (1000 - 3800 K) of the specimen can therefore be obtained. The perfect consistency between the present and previous results justifies the validity of this technique.     

Admissibility for Nonhomogeneous Linear Estimates on Multivariate Random Regression Coefficients and Parameters

61..IntroductionLetA,BaretwomatriceslthesignA>odenotesthatAisanon-negativedefinitesquarematrixFA>BdenotesA-B>OIA>odenotesthatAisaPoSitivedefinitesquarematrix;A>BdenotesA-B>OFp(A)denotesthelinearspaceextendedbycolumnvectorsofAFA denoteSMcore-PenrosegeneralinversionofA,i.e.A satisfies:AA A=A,A AA =A ,A AandAA botharesymmetriclA-denotesthesignu-"generalinversionofA,i.e.A-satisfies:AA-A=A3Adenotestherow-drawingstraightvectorofA;A@BdenotestheKrcrneckerpreductofAandB3tr(A)denot…     

A Highly Stable Organic Luminescent Diradical

It is very challenging to obtain stable room-temperature luminescent open-shell singlet diradicals. Herein we report the first stable Müller's hydrocarbon TTM-PhTTM with luminescent properties. Variable-temperature electron paramagnetic resonance spectroscopy measurements and theoretical calculations show that TTM-PhTTM has an open-shell singlet ground state with a diradical character of 90 %. Because of a small singlet-triplet energy gap, the open-shell singlet ground state can be thermally excited to a triplet state. TTM-PhTTM shows room-temperature deep-red emission in various solutions. Unusually high stability of TTM-PhTTM was also observed owing to effective steric hindrance and spin delocalization. Our results are beneficial to the rational design and discovery of more stable luminescent diradical materials.     

ICP-AES法测定百合中的微量元素

用ICP-AES法对兰州百合和湖南百合、药用百合中的Fe、Mn、Cu、Zn等18种元素进行了分析研究。结果表明,百合中含有丰富的人体必需微量元素;湖南食用百合比兰州百合的微量元素含量高,Fe含量高于兰州百合的5倍之多,Zn含量几乎是兰州百合的10倍之多。加标回收率为83%~106%,该法具有操作简便、快速和准确度高等优点。说明湖南百合具有较高的保健价值,为进一步开发百合提供了科学依据。     

Image encryption by using local random phase encoding in fractional Fourier transform domains

Based on fractional Fourier transform, an image encryption algorithm is proposed and researched. A local random phase encoding is introduced into this algorithm. The data at the local area of complex function is converted by fractional Fourier transform. The local random phase encoding is performed many times. Moreover only one set of random phase data is used in image encryption process. Compare to double random phase encoding, the parameter defining local area can be regarded as the additional key to increase the security of the encryption scheme. Some numerical simulations are achieved to demonstrate the performance of the image encryption scheme.     

Orthogonal变换与Nataf变换对FORM计算精度的影响分析

考虑随机变量的分布类型、功能函数的非线性程度、随机变量的变异性、随机变量之间的相关性等因素的影响,系统地对比分析了基于Orthogonal变换和Nataf变换的一次可靠度方法(FORM)的计算精度。研究表明:当随机变量的变异系数较小时,FORM的计算误差主要来源于Orthogonal变换或Nataf变换引起的非线性,而功能函数的非线性影响相对较小;同时,基于两种变换方法的FORM计算精度随着随机变量偏态系数绝对值的增大而降低;对于正态和对数正态分布类型,两种变换的计算精度相当,此时推荐采用Orthogonal变换;而对于极值Ⅰ型分布和移位瑞利分布类型,当随机变量的变异性和随机变量之间的相关性较小时,两种变换的计算精度相当;反之,当随机变量之间高度相关时,Orthogonal变换的误差较大,而Nataf变换的计算精度较好,此时推荐采用Nataf变换。进一步的研究表明,基于Orthogonal变换和Nataf变换的FORM同样适用于具有隐式功能函数的刚架结构,且两种方法的计算精度相当。     

多嵌段共聚物PET/PEO中的自由体积特性

利用正电子寿命谱的ＰＡＴＦＩＴ和ＭＥＬＴ分析程序,研究了多嵌段共聚物对苯二甲酸乙二酯／环氧乙烷（ＰＥＴ／ＰＥＯ）的自由体积特性．从正电子寿命的最长分量随温度的变化发现,多嵌段共聚物有两个玻璃化转变温度,这表明多嵌段共聚物中ＰＥＯ和ＰＥＴ相的互容性较差．根据浅束缚态理论解释了玻璃化转变温度以下最长寿命分量强度的变化规律,并且利用ＭＥＬＴ分析程序得到了自由体积浓度随温度的分布．