浅论建设项目投资控制的重点

建设项目控制的重点应放在投资决策和设计阶段中,否则会造成巨大的损失。这不仅需要人们改革组织结构和管理体制,更需要从根本上转变思想观念。     

Synthesis and Properties of the Bi-Based Superconducting Powder Prepared by the Pechini Process

Bi-based superconductors are of great interest in high-temperature superconductors. We describe what is believed to be the first synthesis of these materials using the Pechini process, a low-temperature synthetic method that often yields inorganic oxide of excellent phase purity and well-controlled stoichiometry. Using this process, it has been possible to synthesize phase-pure Bi-2223 phase by calcining the appropriate polymeric precursors in air at 800°C for several hours. The superconductivity studies show that the Pechini-synthesized materials appear to offer high-quality performance.     

COREX熔融气化炉热模拟研究

根据ＣＯＲＥＸ熔融气化炉的模拟试验，对预还原矿金属化率，煤种，预还原矿预热温度，煤炭流化床，炉渣，热平衡进行了分析研究，得到了合理的熔融气化炉冶炼参数。     

Morphological characterization of microporous carbon materials

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

A numerical flow simulation based on the rate form of the equation of state

A finite-difference numerical method of solution for the unsteady, incompressible Navier-Stokes equations using primitive variables is presented. The rate form of the equation of state is used for the calculation of pressure. This form of the equation of state is well-suited for use with the unsteady form of the conservation equations (mass, momentum and energy). An implicit algorithm is used for the time integration for greater numerical stability. This method is used to solve a known benchmark problem in steady-state natural convection as a test of steady-state accuracy. The results of the simulation are compared to the benchmark.     

碳酸盐岩油藏改善注水开发效果试验研究

双重孔隙介质的碳酸盐岩油藏在稳定注水采油后岩块系统还存在大量剩余油，而不稳定注水方法可在一定程度上提高水驱油效率。室内物理模型实验、数值模拟计算及现场试验结果一致表明：在碳酸盐岩油藏注水开发后期采用衰竭式降压开采，周期注水等不稳定注水方式，能够提高水驱油效率，改善油藏开发效果，获得良好的经济效益。     

Activity Interaction Coefficients of Si in Cu-Ti-Si Melts at 1550℃

Activitibs of Si in binary Cu-Si and ternary Cu-Ti-Si melts were measured at 1 550℃ by using a method of chemical equilIbrium between gas and liquid. The activity interaction coefficients of Si in the melts have been determined from the experimental data (lny = -5.69. s = 6.69. P2: = -26.22. E; =-43.96) and activity interaction coefficients of Ti in binary Cu-Ti melt at 1550℃ has been estimated from Sommer's data based on the regular solution model (lny =-1 .10. : = 2.95.p:=-2.10).     

Stochastic modelling of temperatures for a full-scale occupied building zone subject to natural random influences

Buildings are usually subject to a variety of stochastic influences. Though the deterministic approach to building thermal modelling is widespread, it cannot easily model the effects of such influences, and a different approach might be better. In this study, stochastic models are derived which describe the thermal behaviour of a full-scale room exposed to the naturally occurring disturbances of climate (temperature, solar irradiance, infiltration), occupancy and appliance usage. A Box-Jenkins time series analysis technique is employed, and univariate stochastic models are fitted to the internal and external air temperature series. The models are validated by comparing the observed temperature with values forecasted ahead (in steps of 1 h) by the models, over a 36-h period; agreement was found to be good. It is concluded that the stochastic modelling approach can be applied successfully to the thermal analysis of a building's behaviour, thereby affording a method which accounts for random influences in a compact model format. The technique has particular relevance to advanced model-based control implemented via ‘intelligent’ digital controllers and building energy management systems, and its application in this respect is discussed.