The deployment of drones to support the last-mile delivery has been initially attempted by several companies such as Amazon and Alibaba. The complementary capabilities of the drone and the truck pose an innovative delivery mode. The relevant optimisation problem associated with this new mode, known as the travelling salesman problem with drone (TSP-D), aims to find the coordinated routes of a drone and a truck to serve a list of customers. In practice, managers sometimes intend to attain a compromise between operational cost and completion time. Therefore, this article addresses a bi-objective TSP-D considering both objectives. An improved non-dominated sorting genetic algorithm (INSGA-II) is proposed to solve the problem. Specifically, the label algorithm-based decoding method, the fast non-dominated sorting approach, the crowding-distance computation procedure, and the local search component are devised to accommodate the features of the problem. Furthermore, the first Pareto front obtained by the INSGA-II is improved by a post-optimisation component. Computational results validate the competitive performance of the proposed algorithm. Meanwhile, the trade-off analysis demonstrates the relationship between operational cost and completion time and provides managerial insights for managers designing reasonable compromise routes.

Nickel-based superalloys have been widely used in the aerospace, petrochemical, and marine fields and others because of their good oxidation resistance, corrosion resistance, stability, and reliability at various temperatures. However, as a nickel-based superalloy is a kind of processed material, in the cutting process a large amount of cutting heat is generated due to the interaction between the tool and the workpiece. At the same time, the low thermal conductivity of the workpiece causes a large amount of cutting heat to accumulate at the contact point, resulting in serious tool wear, reduced tool life, frequent tool changes, and other problems, which increase the production cost of the enterprise. This paper introduces the tool wear mechanisms (abrasive wear, adhesive wear, plastic deformation, chemical wear, etc.) in the machining process of nickel-based superalloys and summarizes the research status of failure mechanisms, tool wear optimization, etc. Based on a review of the existing research, it was found that the purpose of adding tool coatings, optimizing tool materials and cutting parameters, or improving the cutting environment is to control the heat during the processing of nickel-based superalloys to improve the tool environment and prolong the service life. The development prospects of tool wear prevention measures in the field of nickel-based alloy machining are also described.

To develop a non-polluting and sustainable city, urban administrators encourage logistics companies to use electric vehicles instead of conventional (i.e., fuel-based) vehicles for transportation services. However, electric energy-based limitations pose a new challenge in designing reasonable visiting routes that are essential for the daily operations of companies. Therefore, this paper investigates a real-world electric vehicle routing problem (VRP) raised by a logistics company. The problem combines the features of the capacitated VRP, the VRP with time windows, the heterogeneous fleet VRP, the multi-trip VRP, and the electric VRP with charging stations. To solve such a complicated problem, a heuristic approach based on the adaptive large neighborhood search (ALNS) and integer programming is proposed in this paper. Specifically, a charging station adjustment heuristic and a departure time adjustment heuristic are devised to decrease the total operational cost. Furthermore, the best solution obtained by the ALNS is improved by integer programming. Twenty instances generated from real-world data were used to validate the effectiveness of the proposed algorithm. The results demonstrate that using our algorithm can save 7.52% of operational cost.

High strain rate rolling (HRSS) of a ZK60 magnesium alloy at 300 °C with a strain rate from 5 s⁻¹ to 25 s⁻¹ was used to research the effect of the rate on the mechanical properties and damping capacity of the ZK60 alloy. The results show that as the strain rate increases, the tensile strength decreases from 355 MPa at 25 s⁻¹ to 310 MPa at 5 s⁻¹. Two damping peaks (P1 and P2) are detected in the high strain rate rolled ZK60 alloys at different strain rates. The P1 peak appears at low temperatures and is caused by grain boundaries sliding. The P2 peak appears at high temperatures and is caused by recrystallization. As the strain rate increases from 5 to 20 s⁻¹, the dynamic recrystallization (DRX) volume percent rises and the dislocation density decreases, both of which cause the P1 peak to become more and more obvious, and activation energy rises. At the same time, the dislocation density decreases and leads to a decrease in the storage energy, which reduces the recrystallization driving force and shifts the P2 peak to high temperatures. When the strain rate reaches 20 and 25 s⁻¹, DRX occurs fully in the sheet, so the activation energy of the P1 peak and the temperature where the P2 peak appears are basically equal.

BK7 glass, with its outstanding mechanical strength and optical performance, plays a crucial role in many cutting-edge technological fields and has become an indispensable and important material. These fields have extremely high requirements for the surface quality of BK7 glass, and any small defects or losses may affect its optical performance and stability. However, as a hard and brittle material, the processing of BK7 glass is extremely challenging, requiring precise control of machining parameters to avoid material fracture or excessive defects. Therefore, how to obtain the required surface quality with lower cost machining techniques has always been the focus of researchers. This article introduces the properties, application background, machining methods, material removal mechanism, and surface and subsurface damage of optical glass BK7 material. Finally, scientific predictions and prospects are made for future development trends and directions for improvement of BK7 glass machining.

International audienceThis paper investigates the improvement of the hospitalisation admission process of elective inpatients by delay announcement to free patients from blind and long wait, a phenomenon often observed in top Chinese hospitals. We propose a formal simulation model in which relevant resource requirements during the hospitalisation of a patient are represented by an original ‘multistage treatment model’. Other key components of the formal model include impatience of patients, resource capacities and key performance indicators such as the original concept of waiting time visibility. Through sensitivity analysis of the simulation model, we demonstrate the benefits of delay announcement and the value of our ‘multistage treatment model’