人民胜利渠灌区泥沙处理实践与研究

以人民胜利渠灌区泥沙处理的实践来论述引黄灌溉中的泥沙问题 ,提出浑水灌溉中泥沙处理的办法和措施。人民胜利渠是新中国建立后在黄河下游兴建的第一个大型引黄灌区。引黄必引沙 ,泥沙处理的是否得当是引黄灌区成败的关键。四十多年来 ,灌区人民从工程和管理措施入手 ,妥善处理泥沙 ,使灌区得以生存和发展。

Halogen Bonding or Hydrogen Bonding between 2,2,6,6-Tetramethyl- piperidine-noxyl Radical and Trihalomethanes CHX3 （X=CI, Br, I）

The halogen and hydrogen bonding complexes and trihalomethanes （CHX3, X=C1, Br, I） are between 2,2,6,6-tetramethylpiperidine-noxyl simulated by computational quantum chem- istry. The molecular electrostatic potentials, geometrical parameters and interaction energy of halogen and hydrogen bonding complexes combined with natural bond orbital analysis are obtained. The results indicate that both halogen and hydrogen bonding interactions obey the order CI〈Br〈I, and hydrogen bonding is stronger than the corresponding halogen bond- ing. So, hydrogen bonding complexes should be dominant in trihalomethanes. However, it is possible that halogen bonding complex is competitive, even preponderant, in triiodomethane due to the similar interaction energy. This work might provide useful information on specific solvent effects as well as for understanding the mechanism of nitroxide radicals as a bioprobe to interact with the halogenated compounds in biological and biochemical fields.

A Robust Fault Detection and Isolation Scheme Based on Unknown Input Observers for Discrete Time-delay System with Disturbance

This paper proposes a robust fault detection and isolation (FDI) scheme for discrete time-delay system with disturbance. The FDI scheme can not only detect but also isolate the faults. The lifting method is exploited to transform the discrete time-delay system into the non-time-delay form. A generalized structured residual set is designed based on the unknown input observer (UIO). For each residual generator, one of the system input signals together with the corresponding actuator fault and the disturbance signals are treated as an unknown input term. The residual signals can not only be robust against the disturbance, but also be of the capacity to isolate the actuator faults. The proposed method has been verified by a numerical example.

Relaxation Dynamics in Condensation on Weighted Scale-Free Networks

Most of the realistic networks are weighted scale-free networks. How this structure influences the condensation on it is a challenging problem. Recently, we make a first step to discuss its condensation [Phys. Rev. E 74 （2006） 036101] and here we focus on its evolutionary process of phase transition. In order to show how the weighted transport influences the dynamical properties, we study the relaxation dynamics in a zero range process on weighted scale-free networks. We find that there is a hierarchical relaxation dynamics in the evolution and there is a scaling relation between the relaxation time and the jumping exponent. The relaxation dynamics can be illustrated by a mean-field equation. The theoretical predictions are confirmed by our numerical simulations.

Quantum Chemistry Studies on the Free-radical Growth Mechanism of Polycyclic Arenes from Benzene Precursors

The free-radical growth mechanisms for the formation of polycyclic arenes (PCAs) were constructed based on the block unit of benzene, and were calculated by the quantum chemistry PM3 method. Two kinds of reaction paths are proposed and discussed. The calculation results show that the formation of PCAs is only controlled by the elimination of H atom from benzene, and the corresponding activation energy is 307.60 kJ·mol-1. H2 is only the ef-fluent gas in our proposed reaction mechanism, and the calculation results are in accord with the experimental facts.

The expression of the jigging bed porosity and its realizing of the computer detection system

This paper proposes the expression of the jigging bed porosity based on the jumping height of the jigging bed and water wave. This kind of expression can help to realize the jigging process automation and intelligence. The computer detection system is also developed.

The study on the evolution of real estate industry based on the theory of self-organization

Based on some basic principles of self-organization theory including dissipation structure and synergy,the author analyzes the condition,dynamic and evolving route of the self-organization evolution of the real estate industry,and builds synergetic evolution model,calculates out the order parameter of the real estate industry. The paper supplies new methods and tools for further research of real estate industry and contributes to reference of the government for its direction of macro-control.

Challenges of Women Contributing to Food Security in Ghana： Perspectives of Women Farmers in Northern Ghana

Women contribution to all the four pillars of food security （food availability, accessibility, utilization, and sovereignty） has been well established in Ghana and many sub-Saharan African countries. However, the issue of sustainability of their contribution to the food security equation is still a dilemma. This study therefore examined the challenges and vulnerabilities associated with women farmers in accessing and controlling land for sustained agriculture in Northern Ghana. The study was mainly qualitative and utilized various participatory dialogue processes including focus group discussions and key informant interviews of selected women farmer groups, individual farmers, opinion leaders and traditional authorities in eight communities across four districts in three regions of Northern Ghana. The data was analysed thematically. Results of the study showed that women are disadvantaged in all the possible means of acquiring land for agricultural production-- inheritance, marriage, rent, shared cropping, outright purchase, and gift. It was evident that women have appreciable levels of access to land, but have low level of control of such lands for sustained food production. Several factors, such as low income, socio-cultural factors, climate change, mining, urbanization, low level of education, and low levels of awareness of property and inheritance rights, associate women＇s vulnerability to limited land in the study area. The findings of the study imply that any policy geared toward women empowerment in agriculture must not only target their access to land but also consider enhancing their control over agricultural land. The study therefore recommended that in order to increase food production and security in the study regions, there is the need to strengthen women＇s capacity to defend their land tenure rights and enhance their access and control over land within the context of natural resource management.

The Classification of Proper Holomorphic Mappings Between Special Hartogs Triangles of Different Dimensions

The authors discuss the proper holomorphic mappings between special Hartogs triangles of different dimensions and obtain a corresponding classification theorem.