Papers by Author: Yi Xie

Abstract: In order to improve the Micro-oil ignition and low fuel load stable combustion in the thermal power system, the standard k-ε model is used in the analysis of flow field for studying the character of the mixture of coal particles, oil and gas mixture. The trajectories of two-phase flow are simulated by the Level Set Methods (LSM). The results describe the velocity distribution of the X-axis of the two-phase flow, concentration and track of coal particles, the thermal distribution of mixed fluid in the combustion chamber. It provides a theoretical basis for the further study of Micro-oil ignition technology

Abstract: Workflow simulation plays an important role in successful implementation of workflow management. However, workflow simulation usually requires a certain amount of expertise and is used by simulation modeling practitioners rather than business analysis specialists or enterprise managers. So, it is prevented from becoming a mainstream analysis and evaluation tool of a workflow. In order to apply simulation to analysis, evaluation and optimization of the workflow performances, workflow process model for simulation is firstly defined and formalized. Then an approach of translating workflow process model into GPSS simulation model is presented so that workflow simulation model can be built automatically according to the workflow process model. Finally the supporting software tool system has been developed which shows feasibility of the proposed method

Abstract: In order to apply traditional CPM in resource-constrained project scheduling, the activity network is firstly formalized for resource-constrained project scheduling. Then Resource constraint in project is presented and an algorithm of the extended CPM is developed for resource-constrained project scheduling. Finally a case is conducted, which shows the accuracy and effectiveness of the extend CPM.

Abstract: The attenuation of structure vibration is very slow when flexible strucure is stirred external force. It seriously affected the life of flexible structure. Smart structures used piezoelectric ceramics as actuators are an effective manner to solve the problem. This paper uses Fiber Bragg Grating (FBG) as sensors and piezoelectric ceramics as actuators to study the active vibration control for the resonance of the smart beam. Two groups of piezoelectric ceramics will be used for vibration exciter and vibration abatement, respectively. The fiber smart beam is excited to a sharp vibration nearby the particular resonance frequency by controlling the frequency of the vibration excitation. The vibration signal is measured by the FBG sensors and the close loop feedback control is fulfilled by the vibration abatement group, and the vibration amplitude of the fiber smart beam is abated. The experiment results show that the resonance amplitude of the beam is obviously abated by adjusting the frequency, amplitude and phase of the vibration abatement circuit.

Abstract: Workflow performance analysis is the basis of workflow evaluation and optimization. Maximum throughput is an important aspect of workflow performance. In this paper, a process analytic model for workflow execution is firstly presented. Then an algorithm is developed to identify the bottleneck activity and to calculate maximum throughput, which is a good preparation for the further analysis and optimization of workflow. Finally the simulation results show the accuracy of the proposed algorithm.

Abstract: The image of cutting tools provides reliable information regarding the extent of tool wear. In this paper, we propose the theory of image processing based on rough sets and mathematical morphology to analyzing the flank faces which are chosen as our monitoring object. First, through plotting the appropriate subset, the rough sets filter is used to enhancement the image of tool wear. Then, the mathematical morphology theory is applied to process the translated binary image. Finally, tool condition monitoring is realized by measuring the area of tool wear. This paper gives the corresponding monitoring principal and proposes a new algorithm to process the cutting tool image. The algorithm is also flexible and fast enough to be implemented in real time for online tool wear or tool condition monitoring.

Abstract: Surface roughness is an important quality characteristic in grinding. Measurement of surface roughness by means of mechanical stylus is widely done in metrology. In this paper, a new machine vision system has been utilized to quantify the surface roughness of machined surfaces (ground and milled). Compared with other measurement methods, it is accurate, quick and credible. This system is mounted on the grinding machine and automates the measurement process by using computer control to automatically position the CCD and capture digital images of machined surfaces between grinding cycles. It was proposed that the proportional formula was used in calibrating this system, and calibration precision meets application requirement. Not only the statistic character of gray image but also which of edge image were calculated out. These characters include the mean value of pixels (Mean), standard deviation (σ), maximal value (Max) and minimal value (Min), the number of pixels on the examine line(Count), etc. It was found out that the standard deviation value σ of the gray image could express the surface roughness most. The correlation between σ and Ra is established by interpolating σ value used Lagrange interpolation law, and the σ value is converted into Ra value through the calculation procedure finally.

Abstract: The tool wear monitoring system based on the image processing and computer vision has better study value and foreground. During the cutting, the cutting tool is always at the movement state, thus, the real-time collected sequence images by CCD sensor are blurred with noise. As a result, we have to confront the problem how to get the high quality images, which is researched by this paper. The paper analyzes the reasons which causing the image blurred, brings forward a degradation function model and finds the degradation of tool wear images dues to the relative movement. According to this function model and combined with the application of fuzzy theory, the restoration algorithm is obtained. The membership function dealing with degraded images of cutting tools is put forward. It turns out that the images restored by this fuzzy restoration algorithm reach our aim.