Notice of RetractionSet Pair Analysis for Rural Drinking Water Quality
A large number of uncertain problems existing in rural drinking water safety system, it is of great significances to apply Set Pair Analysis (SPA) theory to analyze and study these uncertain problems in rural drinking water safety system. This study applies SPA theory to conduct an integrated evaluation of water quality to rural drinking water safety in Ya'an City, based on classification values of Sanitary Standard for Drinking Water (GB5749-85). This study has worked efficiently in practice. Compared with the same kind of methods which have been found, this paper has the outstanding results for the uncertain problems of health risk assessment of the rural drinking water safety.
Application of attribute recognition method for evaluating on sustained developmental degree of water resource systems.
Taking Ping Ba area as an example, this paper explores the method of comprehensive evaluation on sustained developmental extent of water resources systems and sets up an evaluation model by applying the attribute recognition theoretical model The result shows that it is coherence to the result of the fuzzy comprehensive evaluation method, meanwhile, this method is easy and understood, and it suit for evaluating on system quality with standardsKey words: water resources systems; attribute recognition theoretical model; fuzzy comprehensive evaluation method
Determination of optimal switching angles in the Dual‐Euler method based on round‐off error models
Purpose – Optimal switching angles are investigated for minimizing accumulated numerical errors when the dual‐Euler method is used in the simulation of angular rotation.Design/methodology/approach – First, round‐off errors are theoretically modeled with a simplified mathematical representation of rotation. Round‐off errors take critical roles in the vicinity of indefinite points because they cause major numerical inaccuracy in very large numerical values represented with limited binary numbers. Optimal switching angles of (±π/4, ±3π/4) are derived and numerically examined. With a more practical and severe rotational model, the switching angles are numerically tested.Findings – In conclusion, switching pitch angles of (±π/4, ±3π/4) yield near minimum numerical errors in angular parameters of pitch, yaw, and roll if truncation errors are not dominant by using high‐order integration algorithms and small step sizes. It is also noticed that accumulated numerical errors increase dramatically if pitch and roll a...