Reliability design is one important link to assure the product’s quality. Reliability allocation is the main task of reliability design, which is influenced by cost, manufacturing consistency, and other factors. Reliability, cost, and manufacturing consistency are coupled and influenced by each other. To find the global optimal reliability indices, one modeling and solving method of reliability allocation based on multidisciplinary design optimization was proposed in the paper. The influence factors of reliability allocation were analyzed and calculated or fuzzy processed. The reliability allocation optimization models were created, and the models were decomposed by the calculation frame of collaborative optimization. The genetic algorithm of the system-level optimization and the sequential quadratic programming algorithm of the disciplinary-level optimization were adopted. As one typical electromechanical equipment, CNC cylindrical grinder was allocated of reliability by the method proposed in the paper. The results showed that the cost can be dropped 3.45%, 4.76%, 4.72%, and 8.45% compared by equal allocation method, fuzzy allocation method, AGREE allocation method, and actual cost, respectively. The reliability allocation method proposed in the article can be used in design of electromechanical equipment to reduce costs.

DC arcs are widely used in many fields such as shipbuilding, machinery manufacturing, and aerospace due to their advantages of high energy density, simple structure, and low price. However, there are few studies on the sensitivity of the arc pressure and temperature fields to current and protective gas flow rate. In order to solve this problem, this paper establishes a numerical model for the coupling of DC arc electric–thermal–flow multi-physical fields. Based on this model, the variation rules of the arc temperature, pressure, and potential field with current or protective gas flow rate are studied, respectively, when the current is 100–600 A or the gas flow rate is 18–48 L/min. The results show that the current is the most important factor in the sensitivity of the arc temperature and potential field to the current and protective gas flow rate. With the increase in current, the Joule heat power increases significantly, and the arc central temperature shows a nonlinear increase to 27,000 K. With increasing current, the peak of the pressure field gradually shifts to the region below the top of the wire arc, and the highest pressure increases by 14 times. When the current is small, the increase in argon flow rate can inhibit the spreading of the temperature field by forced convection; when the current is large, the arc contraction with an increasing argon flow rate leads to an anomalous increase in the arc-central temperature. In addition, the energy accumulation mechanism in the strong-current–high-flow-rate coupling region is also revealed, a coupled mathematical model of arc contraction and turbulent loss under the Lorentz force is constructed, and the thermodynamic properties of the arc under the coupling of multi-physical fields are elucidated.

One detecting method for young child being left on school bus based on the FSR (Force Sensing Resistor) sensor array was put forward and the alarm system was designed, which aimed at the frequent occurrence of safety accidents of young children being left on school bus in summer. Four square or circular FSR sensors were combined parallel together and placed on one seat of school bus as one module. Two strip shape FSR sensors were combined parallel together and placed on the ground between seats and on the aisle of school bus as one module. A certain number of modules placed on seats or aisle were combined parallel together and then connected with one input terminal of microcontroller. The resistance of each FSR module is inversely proportional to the pressure being applied. So, whether the young children were left on school bus alone or not can be detected by the resistance of the FSR module. To protect the FSR sensors were not damaged, the FSR sensors were wrapped in two soft silicone cushions. When the young children being left on the school bus alone was detected, the microcontroller would drive the speaker to play the alarm voice for warning the people nearby the school bus to recuse. The FSR sensors could detect the left child on the school bus accurately and the alarm system can warn timely. The detection method and the alarm system can be used for young children school bus to improving the safety of children riding.

School buses serve as the primary mode of transportation for children traveling to and from school, and their safety measures represent a critical safeguard for children’s lives. Nevertheless, incidents in which children are left unattended on school buses—due to inadequate supervision or the children’s own actions—occur with notable frequency and can lead to fatal outcomes. To mitigate or prevent such tragedies, this paper proposes an in-vehicle thermal imaging solution based on infrared array sensors, integrated with a dedicated algorithm to detect whether a child has been left behind in the school bus. The system collects background temperature, presence temperature, and real-time temperature data inside the bus using infrared array sensors. By comparing the real-time temperature difference against a predefined presence temperature difference threshold, the algorithm determines whether a child is present under the current thermal conditions. It then verifies whether the number of positive detections within a specified temperature range meets a preset presence count threshold, thereby reaching a final decision regarding child presence. Experiments identified optimal parameters: a temperature range of 26–33 °C, a double-difference threshold (ε = 1), and a presence count threshold (P = 4). Random testing demonstrated that the proposed technical solution and algorithm achieve an overall detection success rate of 92.5%. This study develops a low-cost, easily deployable, non-contact thermal imaging method capable of identifying forgotten children on school buses with satisfactory accuracy. By detecting retention before harm occurs, the approach enhances the safety of children traveling by school bus.