Synthesis and Herbicidal Activity of 2‐Alkyl(aryl)‐4‐amino‐3‐[alkyl(alkoxy)carbonyl]‐5‐cyano‐6‐[(3‐trifluoromethyl)phenoxy]‐pyridines

To find novel bleaching herbicide lead compounds, a series of novel 2‐alkyl(aryl)‐4‐amino‐3‐[alkyl(alkoxy)carbonyl]‐5‐cyano‐6‐[(3‐trifluoromethyl)phenoxy]‐pyridines was designed and synthesized by the multistep reactions. N,S‐acetal 1 reacted with 2 to obtain multisubstituted pyridines 3 in the presence of zinc nitrate as the catalyst. The target compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l were formed by the oxidation of 3 , followed by the substitution with 3‐(trifluoromethyl)phenol in the presence of potassium carbonate. Their structures were confirmed by IR, ¹H NMR, EI‐MS, and elemental analyses. The preliminary bioassays indicated that some of them displayed moderate herbicidal activity against dicotyledonous weed Brassica campestris L at the concentration of 100 mg/L.     

Effect of Particle Properties on the Break Up of Nanoparticle Clusters Using an In‐Line Rotor‐Stator

This study was carried out to investigate the break up of nanoparticle clusters in a liquid using an in‐line rotor stator. Two types of fumed silica particles were dispersed in distilled water: Aerosil 200 V, which is hydrophilic, has a primary particle size of 12 nm and Aerosil R816 which is based on Aerosil 200 V and surface modified to render it hydrophobic. The article reports on the rheology of the dispersions, particle size analysis, the effect of concentration, and processing conditions such as the rotor speed, that is, the specific power input, and flow rate, that is, the residence time.     

Fluorescent H‐Aggregates Hosted by a Charged Cyclodextrin Cavity

Most macrocyclic host molecules, including cyclodextrins, usually prevent self‐aggregation of the guest organic molecules, by exploiting inclusion complexation of the guest with the host. In this work, it was found that a negatively charged β‐cylcodextrin derivative induces aggregation of a well‐known amyloid sensing dye, Thioflavin‐T, and leads to an unprecedented formation of the rarely observed emissive H‐type aggregates of the dye.     

一类代理多重签名方案的密码学分析与改进

2001年，傅晓彤等提出了一种新的代理多重签名体制，即多个原始签名人分别将签名权力委托给各自的代理签名人，再由这些代理签名人联合生成代表所有原始签名人的数字签名．然而，周红生等（2004）指出他们的方案不存在抗抵赖性以及代理签名者能滥用代理签名权的缺陷，同时给出了一个改进方案．本文指出，周红生等的方案也是不安全的，任一原始签名人或任一代理人都能生成有效的代理多重签名，而且可以任意修改代理签名的期限．为克服他们的安全性弱点，给出了一个改进的方案．     

Markovian receiver collision analysis of high‐speed multi‐channel networks

Two synchronous transmission multi‐channel multi‐access protocols for high‐speed network architecture are studied in this paper. Analytic discrete time Markovian models are developed for finite number of stations and finite number of channels for the symmetric and asymmetric access rights proposed protocols. The effect of receiver collision phenomenon is examined and analysed on the performance measures evaluation and estimated by the probability of packet rejection at destination. Also, numerical results are presented for comparison for various numbers of data channels and stations. Copyright © 2005 John Wiley & Sons, Ltd.     

并行平台上的CFD通用界面标准-第二部分:CFD应用

在建立了并行平台上的CFD通用界面标准后,就可以规范的将一般的CFD程序改为基于通用界面标准的并行程序.在这个标准基础上开发了基于WINDOWS NT系统的WINSOCK并行平台,搭建了基于LINUX系统的PVM并行平台.将这两个平台应用于转子叶尖顶部流动的模拟,捕捉到了激波附面层相互干扰及叶片顶部泄漏等现象;应用于叶轮机械动静叶片非定常气动干涉的数值模拟,验证了PVM平台和通用界面标准的实用性和可行性.     

CFD‐based multi‐objective optimization method for ship design

This paper concerns development and demonstration of a computational fluid dynamics (CFD)‐based multi‐objective optimization method for ship design. Three main components of the method, i.e. computer‐aided design (CAD), CFD, and optimizer modules are functionally independent and replaceable. The CAD used in the present study is NAPA system, which is one of the leading CAD systems in ship design. The CFD method is FLOWPACK version 2004d, a Reynolds‐averaged Navier–Stokes (RaNS) solver developed by the present authors. The CFD method is implemented into a self‐propulsion simulator, where the RaNS solver is coupled with a propeller‐performance program. In addition, a maneuvering simulation model is developed and applied to predict ship maneuverability performance. Two nonlinear optimization algorithms are used in the present study, i.e. the successive quadratic programming and the multi‐objective genetic algorithm, while the former is mainly used to verify the results from the latter. For demonstration of the present method, a multi‐objective optimization problem is formulated where ship propulsion and maneuverability performances are considered. That is, the aim is to simultaneously minimize opposite hydrodynamic performances in design tradeoff. In the following, an overview of the present method is given, and results are presented and discussed for tanker stern optimization problem including detailed verification work on the present numerical schemes. Copyright © 2006 John Wiley & Sons, Ltd.     

具有粘性效应的离心叶轮内部完全三元流场的数值模拟

1前言近年来，随着数值计算技术的进步和电子计算机性能的提高和应用的普及，在求解工程应用中经常遇到的流体定常流动正问题中，过去因受到计算条件的限制而很少采用的直接解三元流动基本方程组的方法已得到了越来越广泛的应用，但对于求解描述实际气体真实流动状况的Navier－Stokes方程，在绝大多数实际条件下为得到定量计算的数值解常常因计算机容量、速度等的限制而无法实现，各种经过简化的湍流模型方程通常只用在作流场的定性分析。在工程使用中仍大多以忽略粘性的欧拉运动方程为主，对实际气体粘性产生的影响则根据经验数据进行总体…     

Elastic Vibrations of a Single-Support Thin-Walled Rotor (Compound Shell) During Complex Rotation

Steady precession vibrations of a single-support thin-walled rotor whose rotation axis is forced to make an additional rotation are simulated numerically. It is established that compared with double-support rotors, single-support rotors are more dynamically compliant and undergo two precession resonances over the range of rotation speeds being considered. Mode shapes of precession vibrations are drawn     

Observation of signature inversion in the πh9/2?vi13/2 oblate band

High-spin states in ¹⁹⁰Tl have been studied via the ¹⁶⁰Gd(³⁵Cl, 5nγ) reaction. The level scheme, consisting of the πh _9/2⊗vi _13/2 oblate band and a cascade with character of single particle excitations, has been established. Spin values have been firmly assigned to the oblate band in ¹⁹⁰Tl, resulting in low-spin signature inversion in the πh _9/2⊗vi _13/2 oblate band for the first time. Based on the similarity of the level structure in doubly odd Tl nuclei, spin values for the oblate bands in ^192–200Tl should be re-assigned, and a consistent low-spin signature inversion has occurred in these oblate deformed nuclei. The low-spin signature inversion phenomena can be interpreted qualitatively by using the 2-quasiparticle plus rotor model including p-n residual interactions.