Study on the Collaborative Design PN-PDDP Model for the Multi-component Coupling Rotor System Based on Petri Nets

AbstractBased on the analysis of the characteristics for the design process in the complex multi-component coupling rotor system, and considering the fact that the multi-components co-design is demanded in the design process of the performance-driven target coupled rotor system, a PN-PDDP (Petri Network for Performance Driven Design Process) model based on the extended Petri nets is presented. The model defines the libraries of the performance and structure characteristics, the traces Token and firing rules. With the model, the flow process of the various coupled information flow is described, and the conflict resolution mechanism for the conflict information is developed. The model also offers guidance on the construction of the related database and design platform, which will provide the important design tools and implementation means for the design of the multi-component coupling turbopump rotor system in the liquid rocket engine

Conflict resolution for product performance requirements based on propagation analysis in the extension theory

Traditional product data mining methods are mainly focused on the static data. Performance requirements are generally met as possible by finding some cases and changing their structures. However, when one is satisfied with the structures changed, the other effects are not taken into account by analyzing the correlations; that is, design conflicts are not identified and resolved. An approach to resolving the conflict problems is proposed based on propagation analysis in Extension Theory. Firstly, the extension distance is improved to better fit evaluating the similarity among cases, then, a case retrieval method is developed. Secondly, the transformations that can be made on selected cases are formulated by understanding the conflict natures in the different performance requirements, which leads to the extension transformation strategy development for coordinating conflicts using propagation analysis. Thirdly, the effects and levels of propagation are determined by analyzing the performance values before and after the transformations, thus the co-existing conflict coordination strategy of multiple performances is developed. The method has been implemented in a working prototype system for supporting decision-making. And it has been demonstrated the feasible and effective through resolving the conflicts of noise, exhaust, weight and intake pressure for the screw air compressor performance design

Rockfall monitoring based on multichannel synthetic aperture radar

Rockfall influences the safety of infrastructure and transportation lines normal operation, application of SAR technology to monitor the rockfall could predict rockfall disaster. One of the most important factors in rockfall target detection is the signal-to-clutter-plus noise ratio (SCNR) after clutter suppression, which should be maximized before rockfall target detection. Through analyzing remainder rockfall target characteristic after clutter suppression, the method of removing quadratic FM component introduced by platform velocity and along track velocity of rockfall target is proposed. After removing quadratic FM component by Dechirp technology, remainder rockfall target is focused in Doppler region image and the SCNR of remainder rockfall target is maximized. So, it has a preferable result in rockfall target detection. To resolve the contradiction between calculated amount and the accuracy of along track velocity, this paper adopts the technology of gradual approach. The effectiveness of the presented method is demonstrated by both theoretic analysis and simulated data

The feasibility and implementation of a golden beam model in Monaco treatment planning system

Background and purpose: Accelerated go live (AGL) is the entire management process for medical accelerators from installation, commissioning, modeling to radiotherapy implementation. Compared with the traditional time-consuming accelerator acceptance process, AGL has established a set of gold standard models based on the big data of thousands of medical accelerators, which makes the accelerator installation greatly optimized in the data acquisition and modeling stage. This study aimed to evaluate and verify an efficient beam modeling method for Monaco treatment planning system (TPS) using golden beam data (GBD). Methods: Two Elekta Infinity™ linear accelerators with agility head in the Department of Radiation Oncology, Fudan University Shanghai Cancer Center, were installed and matched with the GBD. Then, a customer acceptance test (CAT) and beam model validations were performed on measured percentage depth dose (PDD) and profile for open-field (OF) point-doses in a three-dimensional water tank. Furthermore, a total of 16 clinical cases from different sites were used for radiotherapy planning design, measurement and dose analysis to validate and verify the accuracy of the beam model. Results: For beam model verification, the agreement of all validation PDD and profile was larger than 90%, and the majority point passing rate was larger than 95% (99.4% for linac 1 and 98.5% for linac 2). For point-dose validation, 96.8% and 97.2% of OF point measured were found to be within 2% agreement of TPS-calculations for linac 1 and linac 2, respectively. The deviation of R50 and R90 between TPS calculation and measured were within 3 mm at all evaluated points of electron beam. The Gamma passing rate for all plans was greater than 90% when using 3%/3 mm criteria, and point-dose agreement was within 3%. Conclusion: Compared with the traditional accelerator process from installation to commission, the Monaco TPS modeling process AGL based on GBD can not only ensure the model accuracy, but also shorten the entire process time, which has the feasibility of clinical application

Study on the nonlinear transient response for the non-contact mechanical face seal

Considering the tilt of the seal ring, the transient vibration response analysis model of the non-contact mechanical seal is presented. The model is consisted of the transient Reynolds equation, the equation of motion and the equation for solving the high order nonlinear dynamic coefficients of seal. The relative error of the high order nonlinear film force to the linear film force is also obtained. With Euler method, the characteristic parameters of the transient vibration response are obtained, which include the axial vibration displacements and the angle-swing of the static ring. The 14 nonlinear force and 14 nonlinear overturning moment dynamic coefficients for the non-contact mechanical seal are calculated. The results show that the influence of the damping effects of the sealed fluid between the seal gap on the axial vibration displacements and the angle-swing is linear. The film thickness distribution changes with the axial vibration of seal, which will lead to static ring swing, and the swing also can cause the axial vibration of the seal. With the increase of the nonlinear order, the relative error of the nonlinear film force decreases. All of the nonlinear film forces, the non-linear stiffness coefficient and damping coefficient decrease with the seal film thickness increases