Flammability ranking of foliage species by factor analysis of physical and chemical pyric properties

In this paper, factor analysis is introduced to evaluate the flammability of 55 foliage species that may be used in China for construction of the fuel break network of forest strips with lower flammability. Six pyric parameters, i.e. air dry moisture content, absolute dry moisture content, ignition point, ash content, caloric value and extractive content, are measured and used as variables for factor analysis. The covariance analysis shows that four principal factors can be extracted to reflect the flammability in different physical and chemical senses. In terms of the contributions of the four factors to the variances and the physical significance of the relevant parameters, the four factors are, respectively, termed as ‘flaming factor,’ ‘air dry factor,’ ‘ash factor’ and ‘absolute dry factor.’ The stability of the factor analysis method is examined by a different number of samples considered, and the variation degrees of the orderings indicate that the method has high reliability to measure the total flammability of foliage species. The results of the flammability evaluation are verified by comparison with the recommended tree species in the Chinese technology standard. Copyright © 2008 John Wiley & Sons, Ltd.     

熊掌与鱼应兼得--门票涨价的怪圈与解围

风景名胜门票只涨价而不持续发展，势必陷入恶性循环。反之，以大力提高综合效益，则门票可平价，降价，甚至免费，反倒可进入良性互动的循环。     

Composite group vector space method for estimating melting and boiling point of pure organic compound

Composition Group Vector Space (CGVS) method for estimating melting and boiling point T _m , T _b of organic compound has been proposed, and the principle of this method has been elucidated. The models for estimating T _m , T _b have been established and the numerical values of relative parameters have been presented. The average percentage deviations of T _m , T _b estimation are 7.53 and 1.58, respectively, which show that the present method demonstrates significant improvement in applicability to predict the above properties, compared to conventional group methods.     

Synthesis and aggregate formation of poly(styrenesulfonate)-b-poly(ethylene glycol)-b-poly(styrenesulfonate) triblock copolymers in aqueous solution induced by binding with aluminum ions

Summary  Well-defined water-soluble poly(styrenesulfonate)-b-poly(ethylene glycol)-b- poly(styrenesulfonate) (PSS-b-PEG-b-PSS) triblock copolymers with narrow molecular weight distribution (1.29 < M_w/M_n < 1.36) were synthesized in aqueous solution at 70 ^oC via reversible addition-fragmentation chain transfer (RAFT) polymerization. The complex formed by the PSS-b-PEG-b-PSS triblock copolymer coordinated with aluminum ion was investigated with turbidimetry, dynamic light scattering (DSL), zeta-potential, and transmission electron microscopy (TEM). The aggregation formation was based on the neutralization of the SO₃^- groups in the PSS blocks with Al³⁺ ions. The appearance, size and stability of the PSS-b-PEG-b-PSS/Al³⁺ aggregates were controlled by varying the PSS block length and degree of neutralization (DN). At DN = 0.33, where the PSS-b-PEG-b-PSS copolymer was completely neutralized with Al³⁺, the aggregate size increased with increasing PSS block length. The transition from the shrinking coil of small size to the interchain aggregates of large size was found at DN of about 0.33.     

探索小森

对于小森公司来说，最近几年在中国的销售业绩相当不错，小森印刷机在中国市场的占有率一直在稳步提高。中国的印刷市场正在高速增长，而小森能够取得如此佳绩，最根本的原因是积极应对世界印刷市场发展趋势，把深度满足用户的需求放在了首位，正如小森的企业理念——让客户感动。     

传感器可靠性技术—传感器可靠性特征量

介绍已知试验数据如何计算可靠性特征量的点估计和区间估计     

An infrared spectroscopic study of the mechanism of chloromethane conversion to higher hydrocarbons on HZSM5 catalyst

Investigation of the reaction mechanism of chloromethane on ZSM5 is a new topic. In this work an in situ FTIR technique was employed to study the conversion processes of chloromethane, the active sites on HZSM5, and the desorption state of surface species. The catalytic conversion of chloromethane to higher hydrocarbons was also studied. It is demonstrated that chloromethane can be reversibly adsorbed on acidic sites of HZSM5 at room temperature. At 100°C chloromethane is irreversibly and dissociatively adsorbed on the strong acidic sites of HZSM5, on which surface methoxyl is formed as proved by infrared characteristic C-H stretchings of-CH₃ at 2960 and 2870 cm^–1. Alkoxyls are produced and adsorbed on the catalyst surface as characterized by the infrared absorption bands of -CH₂-groups at 1460 and 2930 cm^–1. At 100°C the adsorbed methoxyl and alkoxyls are the main surface species, and a small amount of aromatics might exist as detected by a characteristic absorption band at 1510 cm^–1. Between 100 and 200°C the adsorbed surface methoxyl and alkoxyls are converted to aromatics, and the occupied OH groups partially appear. At temperature higher than 300°C the adsorbed aromatics are thermally desorbed into the gas phase. Aromatics and alkanes are the main products in catalytic conversion. These results reveal that the formation of aromatics from methoxyl and alkoxyls is easier than the desorption of aromatics from HZSM5 catalyst. An alkoxyl mechanism is proposed for the conversion of chloromethane on HZSM5 based upon the experimental results and the three assumptions: (a) The primary C-C bond is formed from surface methoxyl groups via the methoxyl group polarization and C-H bond weakening, (b) The adsorbed alkoxyls are converted to aromatics via hydrogen transfer and bond rearrangement similar to the conventional carbenium ion mechanism for the aromatization of olefins and alkanes on HZSM5. The hydrogen atoms from the aromatization stimulate the desorption of alkoxyls to alkanes. (c) At temperature higher than 300°C surface reactions and desorption of adsorbed species take place simultaneously, determining the product distribution in the catalytic conversion.     

超临界流体络合萃取镧系和锕系元素的研究进展

超临界流体络合萃取是1种可用于萃取金属离子的新型分离技术，它应用于乏燃料后处理和核废物处理中的最大优点是能大幅减少二次废物的产生。文章主要介绍超临界流体的特点、超临界流体络合萃取的基本原理及其影响因素，并对超临界流体络合萃取镧系和锕系元素的研究进展及其在乏燃料后处理工艺研究中的应用进行综述。     

The Growth of a Single Cell/Dendrite in a Directional Solidification Process

Following the original model for a single cell/dendrite growth by Hunt,[5] systematic numerical simulations are carried out with focus on cell shape evolution and tip radius selection in a directional solidification process conducted in a capillary tube. Computations indicate that the anisotropy of solid/liquid interfacial energy and the diameter of a capillary tube have significant influences on the selection of a tip shape. The anisotropy in dilute SCN-salol alloys has been determined through the equilibrium droplet shape method and its value is 1.09 pct. The calculated cell/dendrite shapes with this value of anisotropy agree with experimental observations where a single cell/dendrite of SCN-salol alloys grows in a capillary tube.     

气体灭火自动控制装置的设计原理

通过科研成果转化的气体灭火系统目前己成为我所科技产业中的主导产品。其控制装置是其中关键配套设备。本文就其开发设计中的设计思想、技术原理、技术设计特色等作一阐述