The reasonable dewatering rate in the single-phase water flow plays an essential role in pressure propagation and coal-bed methane production. However, current fluid velocity sensitivity experiments cannot provide an optimum dewatering rate for field coal-bed methane production. This study proposes a new method to optimize the dewatering rate for coal-bed methane wells by assuming the investigation distance reaches the well boundary when the bottom hole pressure declines to the critical desorption pressure. The effect of the stress sensitivity and fluid velocity sensitivity on pressure propagation was first simulated with COMSOL Multiphysics software. The results showed that the expansion area considering the stress sensitivity is shorter than that neglecting the stress sensitivity when the bottom hole pressure reached to the critical desorption pressure at 200 days. The expansion area with high dewatering rate will be shorter about 35 m than that with low dewatering rate at 200 days. The relationship between the maximum investigation distance and required time was established to optimize the dewatering rate by combining the pressure profile considering the influence of stress sensitivity with material balance equation. The new model indicates that the initial permeability, porosity, and cleat compressibility have an important effect on investigation distance. The simulation of these parameters’ sensitivity suggests that the bigger the ratio of initial permeability and porosity, the longer the investigation distance is, and the smaller the cleat compressibility is, the longer the expansion area is. According to this model, we need to take more than 600 days at 0.58 m/d constant dewatering rate to reach the maximum investigation distance of 0.67 mD initial permeability. This work can be conducive to choose reasonable dewatering rate in single-phase water flow for coal-bed methane well production.

Software safety requirements elicitation is very important for assuring software safety. Making use of general safety requirements and criterion through pattern is an effective manner. In this paper software safety requirement pattern definition and description template were given. Classification principles were made to assure the classification rationale. Software safety requirements patterns classification was given to guide patterns building. Hazard command requirement pattern was finally given as an example. Effective organization and description ability for general safety requirements and criterion were verified through the building process and result. This provides the basis for guiding software safety requirements elicitation and analysis.

Abstract:Our study targeted representative urban design guidelines to enhance public understanding. In particular, we concentrated on developing a tool for stakeholders to improve their understanding of urban design guidelines determined by related laws and regulations. In this paper, we suggest that Google Earth can not only display a detailed district plan of the urban design guidelines or related documents but can also offer a possible method for stakeholders to experience the planning site from anywhere via the Internet. Stakeholders can refer to other planning projects on Google Earth at the same time. Thus, urban design guidelines can be more intuitive and dramatic to both professional planners and stakeholders.

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