Modeling and simulation of substation fault diagnosis based on Petri nets
In order to improve the efficiency of the substation fault diagnosis with multiple protections, the proposed method describes protection grades by varied weight of the transition vector in the Petri net models. According to relays and circuit breakers, special markings are produced in the diagnosis results that enhance the identifying capability of error information. The process of fault diagnosis is accomplished by algebra matrix calculation. A simulation on actual substation fault diagnosis process indicates that the improved method has fast calculation speed and high veracity
Power system monitoring using Petri net embeddings
A failure in a power transmission line causes a number of circuit breakers to activate in an effort to isolate the failure and prevent it from corrupting the rest of the power system. Based on information from these physically distributed protective devices, a central controller needs to quickly locate and identify the failure. The task becomes challenging due to the complexity of modern power transmission networks and due to the possibility of sensor failures or incorrect operation of protective devices. A solution to this problem is investigated using Petri net models. Our approach allows concurrent/incremental processing of the information that arrives at the controller and only requires simple calculations (linear checks) during execution time. Most reasoning is implicitly performed at design time, which gives our method an important edge for real-time monitoring. These same techniques can potentially handle multiple failures or perform hierarchical and/or distributed monitoring.
The development of biological systematics : Antoine-Laurent de Jussieu, nature, and the natural system
A reevaluation of the history of biological systematics that discusses the formative years of the so-called natural system of classification in the eighteenth and nineteenth centuries. Shows how classifications came to be treated as conventions; systematic practice was not linked to clearly articulated theory; there was general confusion over the "shape" of nature; botany, elements of natural history, and systematics were conflated; and systematics took a position near the bottom of the hierarchy of sciences.