Seru production is one of the latest manufacturing modes arising from Japanese production practice. Seru can achieve efficiency, flexibility, and responsiveness simultaneously. To accommodate the current business environment with volatile demands and fierce competitions, seru has attracted more and more attention both from researchers and practitioners. A new planning management system, just-in-time organization system (JIT-OS), is used to manage and control a seru production system. The JIT-OS contains two decisions: seru formation and seru loading. By seru formation, a seru system with one or multiple appropriate serus is configured; by seru loading, customer ordered products are allocated to serus to implement production plans. In the process of seru formation, workers have to be assigned to serus. In this paper, a seru loading problem with worker assignment is constructed as a bi-level programming model, and the worker assignment on the upper level is to minimize total idle time while the lower level is to minimize the makespan by finding out optimal product allocation. A product lot can be splitted and allocated to different serus. The problem of this paper is shown to be NP-hard. Therefore, a simulated annealing and genetic algorithm (SA-GA) is developed. The SA is for the upper level programming and the GA is for the lower level programming. The practicality and effectiveness of the model and algorithm are verified by two numerical examples, and the results show that the SA-GA algorithm has good scalability.

Purpose: Top-level operations leaders can drive organizational performance across a broad range of pro-environmental objectives. The authors’ focus is on understanding which specific leadership competencies are most conducive to green performance outcomes. The authors further consider the influence of Lean thinking on the importance of these competencies.Design/methodology/approach: In study 1, of a multi-method investigation, the authors interview executive search professionals, on how green objectives impact top-level operations leadership searches. In study 2, the authors adopt a multi-attribute choice task to examine how Lean thinking impacts competency preferences. Finally, in study 3, the authors merge secondary data on corporate environmental performance with a survey of top-level operations managers’ assessments. This triangulating multi-method approach provides an integrated and holistic view into these dynamics.Findings: Results show particularly strong associations between resource and energy management outcomes and the specific leadership competencies of stewardship. This set of leadership competencies play the greatest role when Lean thinking is deficient.Research limitations/implications: While the authors’ focus is on top-level operations managers, and their under-explored impact on environmental performance, such an impact represents only one dimension of corporate social responsibility (CSR) that these managers may be critically influencing.Practical implications: The associations uncovered in this research suggest critical leadership characteristics to consider in developing and recruiting top-level operations managers, when specific environmental objectives exist.Social implications: The study’s findings draw attention to the importance of leadership characteristics among influential corporate decision-makers, instrumental in the environmental progress of firms.Originality/value: This work fills a critical gap in the authors’ understanding of how top-level operations managers influence green corporate objective, and how their contributions are valued across settings.