Compared with the dimensions of the immature pedicle, the significantly larger size of the corresponding pedicle rib unit provides a more ample space, which accommodates screws with larger diameters. Extrapedicular vertebral body fixation was anatomically feasible for the immature spine. The new procedure should be cautiously applied to avoid potential implant failures or a new deformity because of the growth of the immature spine.
Nowadays, the emerging digital technologies and digitalization trend in safety‐critical industrial process systems are bringing great opportunities for system performance improvements. However, new big challenges are also encountered in the reliability and safety evaluation of large complex industrial process systems due to its multi‐state, multi‐phase dynamic interactions, resilience on software and inter‐dependencies among digital components. The objectives of this study are i) to present an introductory overview of a hybrid computing framework as a supplementary to conventional fault tree analysis toolkit for risk‐oriented reliability analysis in dynamic probabilistic safety assessment context; ii) to illustrate how to combine the three methods of DDET, Markov/CCMT, and GO‐FLOW for integrated risk solutions by a case study of small‐break LOCA in nuclear power plants. Within the hybrid computing framework, the DDET model is implemented based on graph‐based search and sequence diagram refactoring by linking with Markov/CCMT and GO‐FLOW solver for branch probability estimation. The dynamic event tree model is adopted to represent the accident sequence of small‐break LOCA, where the heading events of system failure of digital RPS and phased‐mission ECCS in realization of safety‐critical functions of reactivity control and emergency core cooling are respectively modeled and analyzed by Markov chain and GO‐FLOW method. The demonstration results show that the failure analysis of complex dynamic process interactions together with time‐dependent mission reliability analysis of safety systems involved in accident prevention and mitigation can be easily implemented with accurate modeling and fast evaluation within the hybrid integration platform. The core algorithms and principles implemented for dynamic risk scenarios development by DDET, modeling, and analysis of dynamic process interactions by Markov/CCMT, time‐dependent and multi‐phase mission reliability analysis by GO‐FLOW as well as their integration to provide comprehensive solutions for the application of dynamic reliability in risk assessment are also discussed as open problems for future research.
In this article, we present an optimization method for threshold logic networks (TLNs) based on observability don’t-care-based node merging. To reduce gate count in a TLN, it iteratively merges two gates that are functionally equivalent or whose differences are never observed at the primary outputs. Furthermore, it is able to identify redundant wires and replace wires for removing more gates. Basically, the proposed method is primarily adapted from an ATPG-based node-merging approach which works for conventional Boolean logic networks. To extend the approach for TLNs, we develop a method for computing mandatory assignments of a stuck-at fault test on a threshold gate and a method for conducting logic implication in a TLN. Additionally, to achieve a better optimization quality, we integrate the proposed method with other optimization methods. The experimental results show that the overall optimization method can save an average of approximately 4.7% threshold gates for a set of TLNs which are generated by using the latest TLN synthesis method. The experimental results also demonstrate the efficiency of the optimization method.
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