Metaheuristics for drilling operation scheduling in Taiwan PCB industries

Among all types of production environment, identical parallel machines are frequently used to increase the manufacturing capacity of the drilling operation in Taiwan printed circuit board (PCB) industries. Additionally, multiple but conflicting objectives are usually considered when a manager plans the production scheduling. Compared to the single objective problem, the multiple-objective version no longer looks for an individual optimal solution, but a Pareto front consisting of a set of non-dominated solutions will be needed and established. The manager then can select one of the alternatives from the set. This research aims at employing a variable neighborhood search (VNS) algorithm and a multiple ant colony optimization (MACO) algorithm to solve the identical parallel-machine scheduling problem with two conflicting objectives: makespan and total tardiness. In VNS, two neighborhoods are defined—insert a job to a different position or swap two jobs in the sequence. To save the computational expense, one of the neighborhoods is randomly selected for the target solution which is also arbitrarily chosen from the current Pareto front. In MACO, a two-phase construction procedure where three colonies are employed in each phase is proposed. These two algorithms are tested on a set of real data collected from a leading PCB factory in Taiwan and their performances are compared. The computational results show that VNS outperforms all competing algorithms—SPGA, MOGA, NSGA-II, SPEA-II, and MACO in terms of solution quality and computational time.     

Panel parametric,semiparametric, and nonparametric construction of counterfactuals

We consider panel parametric, semiparametric and nonparametric methods of constructing counterfactuals. We show through extensive simulations that no method is able to dominate other methods in all circumstances, since the true data‐generating process is typically unknown. We therefore also suggest a model‐averaging method as a robust method to generate counterfactuals. As an illustration of the sensitivity of counterfactual construction, we reexamine the impact of California's Tobacco Control Program on per capita cigarette consumption and election day registration (EDR) laws on voters' turnout by different methods.     

The innovation and economic consequences of knowledge spillovers: fit between exploration and exploitation capabilities,knowledge attributes,and transfer mechanisms

The purpose of this study is to investigate the moderating roles of the attributes and transfer mechanisms of knowledge in the relationship between organisational capabilities and innovation and economic performance. Regression analysis on a sample of 120 Taiwanese firms was used to test our model. The findings suggest that the organisational capabilities of exploration and exploitation are positively related to innovation and economic performance. The effect of exploration on performance is positively moderated by tacit knowledge and adaptation knowledge transfer mechanisms. In contrast, exploitation is a stronger predictor of performance when organisations acquire well-defined knowledge and use replication knowledge transfer mechanisms.