Cable trees are used in industrial products to transmit energy and information between different product parts. To this date, they are mostly assembled by humans and only few automated manufacturing solutions exist using complex robotic machines. For these machines, the wiring plan has to be translated into a wiring sequence of cable plugging operations to be followed by the machine. In this paper, we study and formalize the problem of deriving the optimal wiring sequence for a given layout of a cable tree. We summarize our investigations to model this cable tree wiring problem (CTW). as a traveling salesman problem with atomic, soft atomic, and disjunctive precedence constraints as well as tour-dependent edge costs such that it can be solved by state-of-the-art constraint programming (CP), Optimization Modulo Theories (OMT), and mixed-integer programming (MIP). solvers. It is further shown, how the CTW problem can be viewed as a soft version of the coupled tasks scheduling problem. We discuss various modeling variants for the problem, prove its NP-hardness, and empirically compare CP, OMT, and MIP solvers on a benchmark set of 278 instances. The complete benchmark set with all models and instance data is available on github and was included in the MiniZinc challenge 2020.
BackgroundMany countries around the world lack data on the epidemiology of agency response to child maltreatment. They therefore lack information on how many children in need get help and protection or if children stand equal chances across regions to get services. However, it has proven difficult to commit child protection agencies to participation in incidence studies.MethodsThe Optimus Study invested in a continuous collaborative effort between research and practice to develop a data collection for the first national study on the incidence of agency responses to all forms of child maltreatment in Switzerland. An innovative approach of utilizing individual agencies’ standardized data reduced work burden for participation respectably: any arbitrary excerpt of data on new cases between September 1 and November 30, 2016, could be uploaded to a secured web-based data integration platform. It was then mapped automatically to fit the study’s definitions and operationalizations.ResultsThis strategy has led to a largely successful participation rate of 76% of agencies in the nationwide sample. 253 agencies from the social and health sector, public child protection, and the penal sector have provided data.ConclusionsValuing agencies context-specific knowledge and expertise instead of viewing them as mere providers of data is a precondition for representativeness of incidence data on agency responses to child maltreatment. Potential investigators of future similar studies might benefit from the lessons learned of the presented project.
Cable trees are used in industrial products to transmit energy and information between different product parts. To this date, they are mostly assembled by humans and only few automated manufacturing solutions exist using complex robotic machines. For these machines, the wiring plan has to be translated into a wiring sequence of cable plugging operations to be followed by the machine.In this paper, we study and formalize the problem of deriving the optimal wiring sequence for a given layout of a cable tree. We summarize our investigations to model this cable tree wiring problem (CTW) as a traveling salesman problem with atomic, soft atomic, and disjunctive precedence constraints as well as tour-dependent edge costs such that it can be solved by state-of-the-art constraint programming (CP), Optimization Modulo Theories (OMT), and mixed-integer programming (MIP) solvers. It is further shown, how the CTW problem can be viewed as a soft version of the coupled tasks scheduling problem. We discuss various modeling variants for the problem, prove its NP-hardness, and empirically compare CP, OMT, and MIP solvers on a benchmark set of 278 instances. The complete benchmark set with all models and instance data is available on github and is accepted for inclusion in the MiniZinc challenge 2020.
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