Application of data fusion method to fault diagnosis of nuclear power plant

The work condition of nuclear power plant (NPP) is very bad, which makes it has faults easily. In order to diagnose the faults real time, the fusion diagnosis system is built. The data fusion fault diagnosis system adopts data fusion method and divides the fault diagnosis into three levels, which are data fusion level, feature level and decision level. The feature level uses three parallel neural networks whose structures are the same. The purpose of using neural networks is mainly to get basic probability assignment (BPA) of D-S evidence theory, and the neural networks in feature level are used for local diagnosis, D-S evidence theory is adopted to integrate the local diagnosis results in decision level. The reactor coolant system is the study object and we choose 2# steam generator Utubes break of the reactor coolant system as a diagnostic example, The experiments prove that the fusion diagnosis system can satisfy the fault diagnosis requirement of complicated system, and verify that the fusion fault diagnosis system can realize the fault diagnosis of NPP on line timely.     

Analysis of solution findings in the conceptual design of function structures

In the conceptual stage the function design process is realized by the computer aided application. After surveying on the function specification methods and the function modeling, a computer aided function design environment is analyzed. Subsequently based on a module library and principle catalogue, a solution finding process as a part of conceptual design is proposed for a creative design. In addition, a search algorithm to find the solution of adaptable function structure is also discussed. The concepts proposed in this paper can support the subsequent design stages, especially simulation for checking the function structure defects.     

Analysis of signal-obtaining error factor of sensor in gyro

The digital signal-obtaining for gyroscope is given. The single optic-fiber sensor via modulating intensity of light is used as measuring eonlponent . The influence on static transmission properties resulting from the special working environnlent （e. g. cryogenic and vacuum） ,the measure error because of tile reflector shape of rotor,the abnormity of facula from sensor caused by the existence of engraving error,and tile fixing error of sensor and the error of machine tool＇s initial lignnlent are investigated. The mathematic model in every condition is founded, the simulation and relative experiments ale done and the outeome is analyzed. The mathematic model and method of compensating technology are studied and some relative experiments are made. The result of study is usefid to improvement of the signal-obtaining system.     

Research on integrated navigation method for AUV

The principles of the SINS/DVL integrated navigation system are introduced, and the compass status accuracy is compared. When the heading is changed, the dead reckoning algorithm using the heading information of the SINS （Strapdown inertial navigation systems） and DVL （doppler velocity log） is adopted to substitute the SINS/DVL integrated system. The simulation results show that the method can improve the accuracy of integrated navigation system when AUV （autonomous underwater vehicle） is in motion.     

Multi-agent immune recognition of water mine model

It is necessary for mine countermeasure systems to recognise the model of a water mine before destroying because the destroying measures to be taken must be determined according to mine model. In this paper, an immune neural network （INN） along with water mine model recognition system based on multi-agent system is proposed. A modified clonal selection algorithm for constructing such an INN is presented based on clonal selection principle. The INN is a two-layer Boolean network whose number of outputs is adaptable according to the task and the affinity threshold. Adjusting the affinity threshold can easily control different recognition precision, and the affinity threshold also can control the capability of noise tolerance.     

Model and algorithm for container ship stowage planning based on bin-packing problem

In a general case, container ship serves many different ports on each voyage. A stowage planning for container ship made at one port must take account of the influence on subsequent ports. So the complexity of stowage planning problem increases due to its multi-ports nature. This problem is NP-hard problem. In order to reduce the computational complexity, the problem is decomposed into two sub-problems in this paper. First, container ship stowage problem （CSSP） is regarded as “packing problem”, ship-bays on the board of vessel are regarded as bins, the number of slots at each bay are taken as capacities of bins, and containers with different characteristics （homogeneous containers group） are treated as items packed. At this stage, there are two objective functions, one is to minimize the number of bays packed by containers and the other is to minimize the number of overstows. Secondly, containers assigned to each bays at first stage are allocate to special slot, the objective functions are to minimize the metacentric height, heel and overstows. The taboo search heuristics algorithm are used to solve the subproblem. The main focus of this paper is on the first subproblem. A case certifies the feasibility of the model and algorithm.     

Analysis of deformation of rotor and influence on the performance of gyro based on B-spline wavelet FEM

Some construct characteristics and composing material of the new Gyro＇ s rotor are introduced. Some factors resulting in deformation of the rotor surface are analyzed. Under different loads such as the fo,＇ce of deflecting center, the change of temperature, the fo,ce of pressure and couple factors, the deformation of rotor is analyzed with the wavelet finite element simulation software. The vector distributing map of rotor reformation is given. The deformation resulting from the pressure force of photon is studied. Finally, the influence on Gyro＇ s performance because of anomalous surface of rotor due to deformation of rotor is researched and the result is useful to forecast the performance of the drift of gyroscope. The disturbing moment resulting from the deformation of rotor can be compensated using the mathematic method, and provides an important reference for both design and optimization of the rotor.     

Performance comparison of multicast routing protocols based on NS-2

The electronic system in a comprehensive shipboard has a extremely wide bandwidth. It supports synchronized and asynchronous data transmission, multimedia correspondence, and videophone conferencing. In order to guarantee the security and correspondent real time of the communication, choosing a multicast routing protocol based on different applications is a key problem in terms of the complexity of the system. A simulation model was first designed for existing multicast routing protocols in NS-2 and analysis was performed on their corresponding application environments. The experiments proved that PIM-DM based on the shortest-path tree protocol is suitable for communication in the field of comprehensive shipboard. Further work that is necessary is also discussed.     

Effect of rotation speed on temperature field and axial shortening of inertia friction welded GH4169 joints by numerical simulation

A 2D finite element model was established for inertia friction welding of GH4169 nickel-base superalloy based on the ABAQUS environment. The remeshing and map solution techniques were adopted to solve the problem of element distortion. The effect of rotation speed on the temperature field and axial shortening of joints was investigated. The results show that the interface temperature increases rapidly to higher than 900°C within 1 s. And then, it increases slowly to a quasi-stable value. The axial shortening begins to augment quickly when a uniform interface temperature field has formed and the plasticized material is extruded from the interface to form an obvious flash. The rotation speed of the flywheel controls the welding process and has a significant influence on the temperature evolution and axial shortening of joints.     

Investigation of improved approaches to bayes risk decoding

Bayes risk (BR) decoding methods have been widely investigated in the speech recognition area due to its flexibility and complexity compared with the maximum a posteriori (MAP) method regarding to minimum word error (MWE) optimization. This paper investigates two improved approaches to the BR decoding, aiming at minimizing word error. The novelty of the proposed methods is shown in the explicit optimization of the objective function, the value of which is calculated by an improved forward algorithm on the lattice. However, the result of the first method is obtained by an expectation maximization (EM) like iteration, while the result of the second one is achieved by traversing the confusion network (CN), both of which lead to an optimized objective function value with distinct approaches. Experimental results indicate that the proposed methods result in an error reduction for lattice rescoring, compared with the traditional CN method for lattice rescoring.