A differential cluster variation method for analysis of spiniodal decomposition in alloys

A differential cluster variation method (DCVM) is proposed for analysis of spinoidal decomposition in alloys. In this method, lattice symmetry operations in the presence of an infinitesimal composition gradient are utilized to deduce the connection equations for the correlation functions and to reduce the number of independent variables in the cluster variation analysis. Application of the method is made to calculate the gradient energy coefficient in the Cahn-Hilliard free energy function and the fastest growing wavelength for spinodal decomposition in Al-Li alloys. It is shown that the gradient coefficient of congruently ordered Al-Li alloys is much larger than that of the disordered system. In such an alloy system, the calculated fastest growing wavelength is approximately 10 nm, which is an order of magnitude larger than the experimentally observed domain size. This may provide a theoretical explanation why spinodal decomposition after a congruent ordering is dominated by the antiphase boundaries.Comment: 15 pages, 7 figure

Eight-potential-well order-disorder ferroelectric model and effects of random fields

An eight-potential-well order-disorder ferroelectric model was presented and the phase transition was studied under the mean-field approximation. It was shown that the two-body interactions are able to account for the first-order and the second order phase transitions. With increasing the random fields in the system, a first-order phase transition is transformed into a second-order phase transition, and furthermore, a second-order phase transition is inhibited. However, proper random fields can promote the spontaneous appearance of a first-order phase transition by increasing the overcooled temperature. The connections of the model with relaxors were discussed.Comment: 8 pages, 5 figures. Submitted to Applied Physics Letter

A Study on Water Utilization in Chinese Rural Areas

In China, because rural population is great and agriculture is very important in national economy, rural areas have becomes a main sphere of water consume. There exist the problems of water shortage and water waste in the countryside. The conflicts of water resource supply and demand between industry and agriculture are very conspicuous. Various factors that include ideology, finance, technology, management and policy restrict the rational and effective use of water resource. The survey on the villages of Jia Ge Zhuang and Yao Bai Zhuang in Ji County, Tianjin reflects these problems. The government tries to solve the problems by making laws and policies, as well as affording financial and technology support to towns and villages. At the same time, it is necessary for the government to make officials and farmers realize the importance of rational water usage and saving by doing propaganda, coordinating the inter-governments relations, and defining the departments’ duties. For realizing the objective of rational water usage, it is necessary to take measures to construct and perfect irrigation installations by both superior and local governments’ investment and farmers’ labor force. Key Words: Chinese Rural Areas, Water Resource, Rational Use, Farmland, Irrigation System Résumé: En Chine,la population est grande et l’agriculture est très importante dans l’économie nationale. Les régions rurales sont devenues un sphère principal de la consommation d’eau. Il existe les problèmes d’insuffisance d’eau et le gaspillage d’eau dans la campagne. Les conflits sur les resources d’eau fournie et demandée entre industrie and agriculture sont très fréquents. Les facteurs variés tels qu’idéologie, finance, technologie, management et politique limitent l’usage rationel et effectif de ressources d’eau. L’enquête sur les villages de Jia Ge Zhuang et Yao Bai Zhuang dans le pays Ji, Tianjin reflète ces problèmes. Le government tente de résoudres les problèmes par l’élabortion des lois et les poliques, ainsi que le support financierl et technologique aux bourgs et villages. Au meme temps, il est nécessaire pour le government à render conscients les officiels et les paysans l’ importance de l’usage rationel en économisant par la publicité, en coordonnant les relations inter-governmentaux, et en déterminant les tâches des départments. Pour la realiser l’objectif de l’usage d’eau rational, il est nécessaire de prendre des mesures pour construire et perfectionner l’ installations d’irrigation par l’investissement des governements supérieurs et locaux ainsi que les forces des labeurs. Mots clés: Les régions rurales chionoises, Ressource d’eau, usage rationel, fermier, Système d’ Irrigatio

一家三甲医院吸烟与控烟工作状况调查

Objective: To master the hospital smoking status and distribution, for providing a scientific basis for tobacco control measures in hospitals. Methods: A questionnaire was designed. Given a uniform standards, the synchronization investigation was carried out after the implementation of staff training. Results:  The overall smoking rate was 9.66% in the hospital, and smoking rate among males was 25.78%. The smoking rate among administrative and support staffs is higher than the medical staff. Conclusion: Hospital overall smoking rate is lower than average, but smoking rate among males is still high. The hospitals should vigorously strengthen tobacco control training system, and create a smoke-free hospital environment to drive the smoking rates decline.目的  了解医院吸烟现状情况分布，为医院控烟措施提供科学依据。方法  自行设计调查表，对实施调查人员集中培训，统一标准，然后分组同步调查。结果  总吸烟率为9.66%，男性吸烟率为25.78%，行政后勤人员吸烟率高于医务人员。结论  总吸烟率低于平均水平，但男性吸烟率较高。应大力加强系统的控烟培训，创建无烟医院环境，带动居民吸烟率下降