Quantum Direct Communication with Authentication

We propose two Quantum Direct Communication (QDC) protocols with user authentication. Users can identify each other by checking the correlation of Greenberger-Horne-Zeilinger (GHZ) states. Alice can directly send a secret message to Bob using the remaining GHZ states after authentication. Our second QDC protocol can be used even though there is no quantum link between Alice and Bob. The security of the transmitted message is guaranteed by properties of entanglement of GHZ states.Comment: 9 pages, 3 figures and 2 table

Advanced Rotordynamics Analysis through CFD-Informed Machine Learning Mixing Prediction

The Mixing Coefficient (MC) is an uncertain, assumed parameter for predicting the leading-edge temperature of a pad film domain. The conventional approach, employing an assumed MC has shown limitations for accurately predicting rotor-bearing system performance. This leads to a temperature discontinuity problem between pads due to the complete mixing assumption. Also, investigation has shown that the classical Finite-Element-Method (FEM) causes an irregular temperature discontinuity problem near the shaft surface. These problems diminish the accuracy of predictions for rotordynamic response. Therefore, this research proposes (1) full CFD model and (2) a FVM-based 3D Hybrid Between Pad (HBP) model, utilizing CFD databased machine learning ML, to accurately model radial and axial temperature distributions at the leading-edge of a pad film domain. This research provides the specific modeling methodology and simulation results for static characteristics and dynamic coefficient predictions. The modeling approach is also applied to the synchronous instability Morton Effect (ME) analysis. The Morton Effect (ME) is a thermally induced, rotordynamic instability phenomenon. It occurs when the journal in a rotor-bearing system experiences asymmetric heating due to synchronous vibration, resulting in thermal bowing of the rotating assembly. The bow may increase vibration and the asymmetric heating of the journal, which in turn further increases the bow. This positive feedback loop ultimately terminates with the vibration exceeding allowable limits which trips the unit to zero speed. The multiphysics nature of the ME, involving conjugate heat transfer, thermal deformation, fluid flow and vibrations, with broadly separated time constants and stationary and rotating reference frames, presents a simulation modeling challenge. The assumptions and methods employed in prior models yield highly approximate, asymmetric journal temperature predictions, which is a key component of ME prediction. These approaches lead to temperature discontinuity problems between pads and near the journal surface. The novel approach presented here corrects these weaknesses. The developed model shows notable improvements in terms of computation speed, removal of energy conservation violations and agreement with available test data, including the data conducted by the author

Dynamic data validation and reconciliation for improving the detection of sodium leakage in a sodium-cooled fast reactor

Since the leakage of sodium in an SFR (sodium-cooled fast reactor) causes an explosion upon reaction with air and water, sodium leakages represent an important safety issue. In this study, a novel technique for improving the reliability of sodium leakage detection applying DDVR (dynamic data validation and reconciliation) is proposed and verified to resolve this technical issue. DDVR is an approach that aims to improve the accuracy of a target system in a dynamic state by minimizing random errors, such as from the uncertainty of instruments and the surrounding environment, and by eliminating gross errors, such as instrument failure, miscalibration, or aging, using the spatial redundancy of measurements in a physical model and the reliability information of the instruments. DDVR also makes it possible to estimate the state of unmeasured points. To validate this approach for supporting sodium leakage detection, this study applies experimental data from a sodium leakage detection experiment performed by the Korea Atomic Energy Research Institute. The validation results show that the reliability of sodium leakage detection is improved by cooperation between DDVR and hardware measurements. Based on these findings, technology integrating software and hardware approaches is suggested to improve the reliability of sodium leakage detection by presenting the expected true state of the system

Dynamic Game Level Generation Using On-Line Learning

In recent years, many researchers are attracted to computer games research. Capable gamers can easily get bored, while beginners tend to give up after trying several times because the game does not correspond to their level of interest. Therefore, this paper proposes that the user’s play pattern to be modeled on the basis of probability and level designer will dynamically generates the gaming level accordingly. We analyze user’s play pattern and design pattern based on GMM (probability model) and dynamically generate the level with online learning technique adapting the reinforcement technique. The play pattern is modeled using GMM and in order to create game level dynamically, the method of updating the weight of enemy creation using online script is proposed. Finally, we apply our proposed method to a 2D shooting game and introduce user’s play pattern leading to design pattern in the game

Boundary condition coupling methods and its application to BOP-integrated transient simulation of SMART

The load-following operation of small modular reactors (SMRs) requires accurate prediction of transient behaviors that can occur in the balance of plants (BOP) and the nuclear steam supply system (NSSS). However, 1-D thermal-hydraulics analysis codes developed for safety and performance analysis have conventionally excluded the BOP from the simulation by assuming ideal boundary conditions for the main steam and feed water (MS/FW) systems, i.e., an open loop. In this study, we introduced a lumped model of BOP fluid system and coupled it with NSSS without any ideal boundary conditions, i.e., in a closed loop. Various methods for coupling boundary conditions at MS/FW were tested to validate their combination in terms of minimizing numerical instability, which mainly arises from the coupled boundaries. The method exhibiting the best performance was selected and applied to a transient simulation of an integrated NSSS and BOP system of a SMART. For a transient event with core power change of 100–20-100%, the simulation exhibited numerical stability throughout the system without any significant perturbation of thermal-hydraulic parameters. Thus, the introduced boundary-condition coupling method and BOP fluid system model can expectedly be employed for the transient simulation and performance analysis of SMRs requiring daily load-following operations