钴系双亚胺基吡啶配合物/甲基铝氧烷体系催化乙烯齐聚

合成了 2种双亚胺基吡啶钴系催化剂 ,以甲苯为溶剂 ,甲基铝氧烷 (MAO)为助催化剂 ,用于催化乙烯齐聚合成线性α 烯烃。探讨了催化剂浓度、反应温度、n(Al) /n(Co)以及苯胺的不同对位取代基等因素对催化活性和齐聚产物分布的影响 ,找到了一些有价值的规律     

HYDRAULICS OF COMPOUND CHANNEL WITH VEGETATED FLOODPLAINS

1. INTRODUCTIONThe Pearl River delta is often subject to typhoons and heavy rainfalls. Big waves generated by typhoons cause scouring, even collapsing and breaching of river embankments. Facts have proved that the effectiveness for wind and ship wave prot…     

One-minute global irradiance probability density distributions conditioned to the optical air mass

Knowledge of the temporal variability of the solar irradiance is important to study solar energy systems involving thermal and photovoltaic processes. The differences between hourly and instantaneous values of the clearness index considerably affect the utilizability of photovoltaic systems. In this work, we analyzed the probability density distributions of one-minute values of global irradiance, conditioned to the optical air mass, considering those as an approximation to the instantaneous distributions. The study reveals that the bimodality that characterizes these distributions increases with optical air mass. We propose the use of a functional form based on Boltzmann's statistics in order to describe these distributions. This function can be used for the generation of synthetic radiation data. Expressing the distribution as a sum of two functions provides an appropriate modeling of the bimodality feature that can be associated with the existence of two levels of irradiation corresponding to two extreme atmospheric situations, cloudless and cloudy conditions.     

Empirical Characterization of Session–Based Workload and Reliability for Web Servers

The growing availability of Internet access has led to significant increase in the use of World Wide Web. If we are to design dependable Web–based systems that deal effectively with the increasing number of clients and highly variable workload, it is important to be able to describe the Web workload and errors accurately. In this paper we focus on the detailed empirical analysis of the session–based workload and reliability based on the data extracted from actual Web logs of eleven Web servers. First, we introduce and rigourously analyze several intra–session and inter–session metrics that collectively describe Web workload in terms of user sessions. Then, we analyze Web error characteristics and estimate the request–based and session–based reliability of Web servers. Finally, we identify the invariants of the Web workload and reliability that apply through all data sets considered. The results presented in this paper show that session–based workload and reliability are better indicators of the users perception of the Web quality than the request–based metrics.     

Singular eigenfunction analysis of transport problems with spatially dependent cross sections — An overview

A substantial amount of recent work has been done in applying singular eigenfunctions to transport problems whose cross sections vary continuously with position. In this article we survey the methodology and results so far obtained, and we briefly discuss some of the many open questions.     

Discontinuity, decision and conflict

Summary The motivation for this paper arises out of the authors experiences in modelling real decision makers where the decisions show not only a continuous response to a continuously changing environment but also sudden or discontinuous changes. The theoretical basis involves a parametric characterisation of the environment, a decision makers perception of it in terms of a twice differentiable Distribution Function and a bounded Loss Function. Under a specified, minimizing dynamic, the resultant Expected Loss Function satisfies the conditions for a potential function and Thoms Catastrophe Classification Theorem may be used to assess the singularity points and the thresholds at which jump decisions are taken. The paper describes the theory, summarises some results on unimodal distributions illustrated by jump decisions and population polarisation. Mixture distributions are then examined and the E^* models defined. These are then briefly illustrated by reference to models which have been constructed in relation to Prison Riots, Agricultural and Economic modelling.     

On discrete multivariate distributions symmetric in frequencies

In this paper we describe a new class of discrete multivariate distributions which verify that their probability mass function is invariant when their univariate variables are permuted. These distributions may be generated by a multivariate extension of the Gauss function₂ F ₁ with matrix argument. A methodology that permits the fit of these distributions to real data is developed. A fit of a distribution for bivariate real data is shown and is compared with fits obtained by means of other usual bivariate distributions generated by extensions of the Gauss function.     

注入低能重离子在模拟细胞中的能量沉积

用Ｍｏｎｔｅ Ｃａｒｌｏ法模拟计算了３０ｋｅＶ和２００ｋｅＶ的Ｎ＾＋与１１０ｋｅＶ的Ｆｅ＾＋模拟细胞中本身及级联离子非弹性散射产生的电子，分子振动的能量沉积；讨论了电子分子振动的总能量沉积的深度分布。     

An inequality for the empirical D.F. in the non–I.I.D. case

A generalization to the non-i.i.d. case of an inequality for the empirical df. due to Mason (1981) is proved     

高压输电线路用复合绝缘子电位和电场分布的计算与改善

采用模拟电荷法和有限元法计算高压线路用复合绝缘子的电场分布和电位分布，讨论了改善复合绝缘子电场和电位分布的措施。为验证计算结果，还进行了复合绝缘子的电位分布试验。