(Z)-1-[2-(Trifluoro­meth­yl)benzyl­idene]thio­semicarbazide

In the crystal structure of the title compound, C9H8F3N3S, all atoms except for two of the F atoms are located on a mirror plane. In the crystal, the molecules are connected by N—H⋯S hydrogen bonds, forming a mol­ecular tape along the a axis

Optimal Cost-Effective Maintenance Policy for a Helicopter Gearbox Early Fault Detection under Varying Load

Most of the existing fault detection methods rarely consider the cost-optimal maintenance policy. A novel multivariate Bayesian control approach is proposed, which enables the implementation of early fault detection for a helicopter gearbox with cost minimization maintenance policy under varying load. A continuous time hidden semi-Markov model (HSMM) is employed to describe the stochastic relationship between the unobservable states and observable observations of the gear system. Explicit expressions for the remaining useful life prediction are derived using HSMM. Considering the maintenance cost in fault detection, the multivariate Bayesian control scheme based on HSMM is developed; the objective is to minimize the long-run expected average cost per unit time. An effective computational algorithm in the semi-Markov decision process (SMDP) framework is designed to obtain the optimal control limit. A comparison with the multivariate Bayesian control chart based on hidden Markov model (HMM) and the traditional age-based replacement policy is given, which illustrates the effectiveness of the proposed approach

Mean change-point model for aero-engine component faults

Recognizing aero-engine component faults is important in prognostics and health management research, particularly in engine monitoring systems and condition-based maintenance. The former primarily concentrates on recognizing engine working parameters and component performance, and neglects quantitative changes in component faults. Taking lubricating oil consumption as an example, quantitative changes in component faults are analyzed using a mean change-point model based on change-point theory. The change-point stage is presented through the minimum variance algorithm. The change point corresponding to the failure mode is tested using exhaust electrostatic data from a turbojet engine life span experiment to verify the validity and feasibility of the theory

On the Unique Development Path of Universities of Applied Sciences

The transition of universities from academy-oriented to application-oriented has become a paramount mission for the management. And the revelation of the path for the unique development lies in the six aspects below: locating specific talents-cultivating goals, innovating educational plans, developing distinctive teaching resources, enhancing instructions for students' vocation and employment, optimizing teaching equipment and increasing publicity