Accurate linear brake-pressure control in a hydraulic control unit (HCU) of the vehicle dynamics control system, such as the electronic-stability control (ESC) system, can improve the control performance while significantly reduce noise and brake paddle vibration during the transient high-frequency brake-pressure control process. To minimize system cost, only simple switching solenoid valves and a master cylinder pressure (MCP) sensor are used in the ESC, thus an accurate real-time sensorless spool-position estimation is the key to the linear pressure controller. In this paper, a new sliding-mode controller (SMC) integrated with a nonlinear sliding-mode observer (SMO) is proposed to achieve a real-time linear controller for the switching valve in the HCU. First, a nonlinear SMO is used to observe the spool position based on the voltage and current values of the solenoid coil, from which the flow rate of brake fluid in the HCU of the ESC and the wheel cylinder pressure (WCP) can be deduced based on a specific hydraulic model of the solenoid valve and the braking system. Then an SMC is employed to adjust the spool position for accurate linear pressure control, taking into consideration the nonlinear characteristics of the electromagnetic force, the dynamic flow force, and the flow rate of the solenoid valve at different openings. Simulations and experiments were conducted, and the results supported the tracking ability of the sensorless linear pressure controller in different conditions. This study may provide a useful method to realize real-time linear control of high-frequency switching valve comparable to a high-performance proportional valve.

This paper presents a risk assessment method for a ship’s power system under the conditions of an engine room fire based on the expert comprehensive evaluation (ECE) method combined with the fuzzy fault tree analysis (FFTA) method. The composition of the main engine system in the engine room and the failure logic of each subsystem were analyzed, and the fuzzy fault tree of a ship engine room fire was constructed. The probability of system failure and the importance of basic events were calculated. The fire safety risk assessment model was established using the safety risk matrix. The risk assessment of a ship engine room fire was implemented. The results demonstrated that the fire frequency of the ship engine room was 5.232 × 10⁻⁶ h⁻¹. The fire risk of the main engine fuel system was the highest. Fuel leakages from diesel supply tanks and heavy fuel oil tanks are the main cause of accidents. The proposed method eliminated the influence of incomplete statistics in the risk assessment process and improved the accuracy and credibility of the reassessment results.

This paper proposes a dynamic evolutionary model to quantify the domino effect of ship engine room fires. Based on the spatial and temporal characteristics of fire accidents, the dynamic probability of the domino effect of multiple accident units is calculated using matrix calculation and Monte Carlo simulation. The uncertainties of shipboard personnel, automatic detection systems, sprinkler systems, and the synergistic effects of multiple escalation vectors from different units are addressed. The dynamic probability of the domino effect of multiple accident units is calculated, and a risk assessment of complex fire scenarios in ship engine rooms is implemented. This study also presents the model feasibility in terms of fire risk assessment in cabins with numerous pieces of equipment. The results indicate that 2 min and 4 min are vital time nodes for the development and spread of fires. The extinguishing work on key equipment in the path of the fire's spread can effectively restrain its further expansion. The results can provide critical references for ship fire prevention, fire suppression, and fire protection design.