一种测定尼龙-11特性粘度的方法

在采用稀释作图外推法测定尼龙 - 11特性粘度的大量实验基础上 ,研究确定了用乌氏粘度计单点法测定尼龙 - 11特性粘度经验公式中的经验常数 ,通过与稀释法的比较 ,检验其准确度和精确度。结果表明 ,误差小于± 0 5%的单点法可用于测定尼龙 -11的特性粘度     

一种简单通用制备纳米羟基磷灰石的方法

详细介绍了如何在普通的实验条件下获得纳米羟基磷灰石的方法。采用化学沉淀法以Ca(H2PO4)2.H2O和Ca(OH)2为原料,聚丙烯酸纳为稳定剂,磁力搅拌器搅拌并辅以超声波作用,通过X射线衍射、透射电镜及细胞共培养评价所制备的材料。结果成功地制备了羟基磷灰石纳米粒子,粒径20～50nm,形貌呈细针状,集成羽毛状均匀分布,羽毛根部宽约20～30nm;并且这些纳米粒子与细胞的共培养效果良好。     

烃类临界性质估算的基团向量空间方法

引　言由于临界参数实验测定的困难 ,到目前为止只有几百种物质有实测数据 ,在生产和科研中常会遇到临界性质未被测定的物质 ,需要进行估算 .烃类临界性质的估算用得较多的是简单基团贡献法 ,有Ｊｏｂａｃｋ和Ｒｅｉｄ法[1] 、Ｌｙｄｅｒｓｅｎ法[2 ] 、Ａｍｂｒｏｓｅ法[3 ] 、Ｌｙｍａｎ法[4 ] 等 .这些方法考虑的只是构成有机物的 39个简单基团 ,其优点是简便易用 ,但缺点是准确度较差 ,且难以区别同分异构体 .为了克服上述缺陷 ,复合基团贡献法开始出现 .复合基团贡献法是把相邻的两个或两个以上简单基团的加和作为分子的独立结构单元 ,…     

A NEW GROUP CONTRIBUTION METHOD FOR ESTIMATING MELTING AND BOILING POINTS OF ORGANIC COMPOUNDS

A new division method of molecular structural units involving group-adjacent atom pairs has been developed. Expressions for estimating basic physical properties T_b and T_m have been proposed, with the numerical values of relative structural unit parameters presented. The average percent deviations of estimation of the above two physical properties are 1.20 and 7.75, respectively.     

A NEW GROUP CONTRIBUTION METHOD FOR ESTIMATING MELTING AND BOILING POINTS OF ORGANIC COMPOUNDS

A new division method of molecular structural units involving group-adjacent atom pairs has been developed. Expressions for estimating basic physical properties T_b and T_m have been proposed, with the numerical values of relative structural unit parameters presented. The average percent deviations of estimation of the above two physical properties are 1.20 and 7.75, respectively.     

烷烃结构异构数新的计算方法

设W_n、Q_n和X_n分别表示n-碳烷(C_nH_(2n n2)n-碳炔(C_nH_(2n-2))和n-碳烯(C_nH_(2n))的同分异构体数,作者发现了下列公式: W_n=Q_(n 2) (1-(-1)~n)/2Q_(n 3)/2-X_(n 1)并算出W_(40)=62,481,801,147,341。(Henze和Blair算出W_(40)=62,491,178,805,831)和W_(50)=1,117,743,651,746,953,270     

冰箱内胆真空成型模具设计方法

针对冰箱内胆体积大、壁薄、形状复杂的特点，根据塑料模具设计程序，围绕冰箱内胆真空成型工艺特点，介绍冰箱内胆真空成型模具设计所涉及的内容及设计方法，包括制品结构分析、设计资料的准备、成型体设计、抽芯机构设计、抽气孔设计、加热和冷却系统设计、密封结构设计和切边装置设计等。     

A GENERAL MODEL FOR MOVING BOUNDARY PROBLEMS -APPLICATION TO DRYING OF POROUS MEDIA

ABSTRACT

This work presents a general model to describe momentum, heat and mass transfer for moving boundary problems. The equations are obtained supposing an instantaneous superposition of a moving volume with velocity V_s (Lagrangean reference frame) over a stationary volume in the stream velocity v (Eulerian reference frame)The set of equations for multicomponent single-phase systems is applied to porous media (multi-phase systems) using the volume-averaging method. Depending on the assumptions about the behaviour of the system, it is possible to obtain the different models proposed in the literature, showing the generality of the model proposed in this work. Numerical results were compared to experimental data of Kaolin drying during the shrinking stage. These results showed a good agreement.     

一种研究风轮叶片固有频率的方法

提高风轮叶片挥舞频率以避免风机运行时发生共振问题,是叶片铺层设计的一个重要环节。本文在风轮叶片铺层设计实践的基础上提出了一种研究复合材料风轮叶片频率的方法,给出了该方法的理论基础,并通过一个风轮叶片铺层实例说明了该方法的具体实施过程,验证了其可行性和可靠性。该方法能够定量地表征叶片每个截面的铺层方案对叶片频率的影响,可指导叶片铺层设计者如何更快找到调整叶片铺层的最优方案,从而更有效地提高叶片挥舞频率。     

DISTRIBUTIONS OF LEAST SQUARES ESTIMATORS OF AUTOREGRESSIVE PARAMETERS FOR A PROCESS WITH COMPLEX ROOTS ON THE UNIT CIRCLE

Abstract. Asymptotic distributions of the autoregressive parameters in the AR(2) model are derived, when the characteristic polynomial has a pair of complex roots on the unit circle. Percentage points are tabulated based on simulations from the asymptotic formulae. The usefulness of the asymptotic results in finite sample situations is investigated by a Monte Carlo study, and an illustrative example is given.     

调整浇口解决电池槽产品缺陷的方法

针对汽车蓄电池槽注射成型过程中出现的问题,详细阐述了利用调整浇口改善电池槽缺陷的方法,并对调整成型工艺改善电池槽缺陷的方法也进行了介绍.经生产实践验证,利用调整浇口改善电池槽缺陷的方法操作可行,能够保证电池槽的质量.     

ON THE APPLICATION OF A CONSUMER PREFERENCE-BASED METHOD FOR DESIGNING PRODUCTS TO WINE FERMENTATION MONITORING DEVICES

This article applies a recently proposed procedure for product design (Bagajewicz, 2007 Bagajewicz , M. ( 2007 ). On the role of microeconomics, multi-scale planning and finances in product design , AIChE J. , 53 ( 12 ), 3155 – 3170 . [Google Scholar]) to the design of a wine fermentation monitoring device. The procedure is based on connections made between consumer preferences and the characteristics of the product; it includes a price-demand model and maximizes the profit by simultaneously changing product characteristics and product price, something that has not yet been applied to devices. We conclude that, unlike other cases, a product that maximizes consumer satisfaction can be successfully marketed. In conclusion, the study is mostly devoted to showing how the methodology applies to this segment of industry, rather than to proposing the best device.     

A SIMPLE CONDITION FOR THE EXISTENCE OF SOME STATIONARY BILINEAR TIME SERIES

Abstract. A sufficient condition is derived for the existence of a strictly stationary solution of some bilinear time series which may have infinite variance innovations. This condition is equivalent to the condition that a polynomial of degree r has no zeros within the unit circle. In the special case when the innovations have finite variance, the computational effort involved in checking this condition is significantly reduced compared with checking the stationarity conditions given by Bhaskara Rao et al. and Liu and Brockwell which requires a knowledge of the maximum eigenvalue in the absolute value of an r ² x r ² matrix.     

近化学计量比铌酸锂晶体生长的新方法

在计算机温场模拟的基础上,探索设计了悬挂式双坩埚和均匀加料装置.在富锂(Li2O摩尔分数为58.5%)熔体中采用提拉法生长了φ50mm×50mm的近化学计量比铌酸锂晶体.测量结果表明:晶体的紫外吸收边发生了明显的蓝移,测得Li摩尔分数达到49.87%.利用干涉仪测量样品的光学均匀性,生长晶体均方根折射率不均匀性△n=7.250×10-5cm-1.     

硅质集料碱活性新检测方法主要参数

较系统地研究了集料碱硅酸反应动力学和碱活性检测方法中的一些主要参数,其中包括反应温度、反应时间、养护碱浓度、灰砂比、水泥碱含量等。根据研究结果,选择了适宜的试验条件,为建立新的硅质集料碱活性试验方法确定主要参数提供了理论依据。     

数据处理组合法在橡胶配方设计回归建模中的应用

通过均匀设计安排橡胶配方试验，进而用数据处理组合方法（ＧＭＤＨ）建立高精度的回归模型。丁基橡胶配方实例表明，ＧＭＤＨ是目前较好的一种橡胶配方回归设计方法。     

一种实时监测环氧树脂固化过程中化学收缩的方法

树脂固化过程中的化学收缩会使复合材料产生缺陷,而这些缺陷会极大降低复合材料的性能。本文在选用传统毛细管膨胀计的基础上通过添加一个对照瓶以及选用PE袋的做法,找到了一种快捷、高效、高精度、高适用性的化学收缩测试方法。通过建立化学收缩与固化度之间的联系,证实了化学收缩独立于温度和时间,仅与固化度呈现一种双线性关系。总体来看在固化度0.28(初步凝胶点)左右直线斜率发生变化,直线前半段斜率约为42.54,后半段斜率约为64.63,树脂完全固化时总的化学收缩率为7.55%。研究表明,上纬2511-1A/BS树脂体系凝胶后化学收缩率远大于凝胶前的化学收缩率。     

舰艇复合材料结构可靠性设计方法探究

可靠度是衡量结构物固有可靠性水平的重要指标之一,正确选取可靠性分析方法以及可靠度计算方法是开展舰艇用复合材料结构可靠性设计工作的基础和保障。舰艇用复合材料结构工作环境复杂,加之复合材料本身具有非均匀、各向异性等性质,力学性能比传统金属材料复杂得多,离散度也大,导致结构可靠性设计问题相对突出。对此,分析了舰艇用复合材料结构强度特性及其分布规律,提出基于应力-强度干涉模型进行舰用复合材料结构可靠性分析,采用B基准设计许用值的安全系数法开展可靠度计算的可靠性设计技术途径。二者联立,在求解问题能力及结果准确性等方面具有明显的可操作性和优越性,对开展舰艇用复合材料结构可靠性设计具有重要的参考意义。     

一种预测单向玄武岩纤维复合材料横向弹性模量的方法

根据单向玄武岩纤维复合材料中纤维排列方式,考虑几何对称性,并引入应变协调假设,提出了一种矩形代表性单元。根据代表性单元内纤维和基体的分布推导出单向玄武岩纤维复合材料的横向弹性模量。与实验、其他理论的结果比较表明,该代表性单元方法可以较好地预测单向玄武岩纤维复合材料的横向弹性模量。     

A NEW METHOD OF CALCULATING TERNARY MASS TRANSFER WITH A NON TRANSFERRING SPECIES BASED ON GILLILAND'S PARAMETRIC SOLUTION OF THE MAXWELL-STEFAN EQUATIONS FOR THE FILM MODEL

This paper presents a solution for the problem of multiple roots in Gilliland's parametric solution of the Maxwell-Stefan equations. Based on it a new algorithm for calculating ternary mass transfer with a non transferring species is obtained. This new algorithm demonstrates rapid and stable convergence. In contrast to the well known calculation of mass transfer in multicomponent mixtures using the matrix solution of the Maxwell-Stefan equations the new algorithm simplifies the calculation by avoiding any matrix operations.