The disassembly of spent lithium batteries is a prerequisite for efficient product recycling, the first link in remanufacturing, and its operational form has gradually changed from traditional manual disassembly to robot-assisted human–robot cooperative disassembly. Robots exhibit robust load-bearing capacity and perform stable repetitive tasks, while humans possess subjective experiences and tacit knowledge. It makes the disassembly activity more adaptable and ergonomic. However, existing human–robot collaborative disassembly studies have neglected to account for time-varying human conditions, such as safety, cognitive behavior, workload, and human pose shifts. Firstly, in order to overcome the limitations of existing research, we propose a model for balancing human–robot collaborative disassembly lines that take into consideration the load factor related to human involvement. This entails the development of a multi-objective mathematical model aimed at minimizing both the cycle time of the disassembly line and its associated costs while also aiming to reduce the integrated smoothing exponent. Secondly, we propose a modified multi-objective fruit fly optimization algorithm. The proposed algorithm combines chaos theory and the global cooperation mechanism to improve the performance of the algorithm. We add Gaussian mutation and crowding distance to efficiently solve the discrete optimization problem. Finally, we demonstrate the effectiveness and sensitivity of the improved multi-objective fruit fly optimization algorithm by solving and analyzing an example of Mercedes battery pack disassembly.

Purpose: The aim of this paper was to build a performance evaluation index system for the combination of medical and old-age care services in pension institutions of China. Methods: A two-stage data envelopment analysis (DEA) is used to evaluate the performance of 30 pension institutions in China. Results: The results show that the two-stage DEA accounted for a relatively high affiance of medical and nursing care services, but resource allocation still needs to be further optimized. Institutions with ineffective DEA need to reduce the five factors of operations, management, fixed assets, technology and services in the input dimension. Conclusion: In the output dimension, the service evaluation effect and safety management effect need to be improved. The performance of combined old-age care and medical care in old-age institutions can be improved in terms of investment in fixed assets, methods of capital subsidies, supervision and management, as well as standardized operations.

Background: In the context of China’s aging population, comprehensive medical care, convenient diagnosis, comprehensive medical care and elderly care services are increasingly needed. But China's medical care and elderly care service system is still immature. This study aims to build a performance evaluation index/criteria system for the combination of medical care and elderly care services and present an empirical approach to assess them.Methods: A two-stage DEA approach is taken: 1) establish a performance evaluation index system for the combination of medical care and elderly care services, 2) adopt a two-stage DEA to evaluate the performance of 30 pension institutions in China, and 3) Determine and identify important criteria to improve the efficiency of pension institutions. Results: The results show that the two-stage DEA accounted for a relatively high affiance of medical and nursing care services, but resource allocation still needs to be further optimized. Institutions with ineffective DEA need to reduce the five factors of operations, management, fixed assets, technology and services in the input dimension. In the output dimension, the service evaluation effect and safety management effect need to be improved. The performance of combined old-age care and medical care in old-age institutions can be improved in terms of investment in fixed assets, methods of capital subsidies, supervision and management, as well as standardized operations.Conclusions: This study establish a performance evaluation index system for the combination of medical care and elderly care services and present a two-stage DEA empirical approach to evaluate the performance of 30 pension institutions in China, which provides the method supports for decision-makers and researchers in performing evaluation of pension institutions in China, outlines the suggestions in improving them.