Applied Mechanics and Materials Vols. 380-384

Abstract: In order to monitor states of the rotary machine in time and ensure its performance, it is very important to analyze the evolution from the normal state to the fault state. In the paper, a new method is proposed to improve the precision of fault diagnosis. Firstly, the character extraction with mutative scales (CEMS) is applied to achieve the characteristic values. Secondly, the Hidden Semi-Markov model is built to identify the different running states. Thirdly, the new method is compared with the traditional one by the example of bushing abrasion of the connecting rod in diesel engine. According to the simulation and experiment researches, it indicates that the signal characters with more state information can be obtained pertinently by using the CEMS. And the accuracy of recognition is 97.33% in the 150 test samples, improved evidently than the traditional one. And the new character extraction method can be used in the technology domain widely.

Abstract: Gate control TWT damaged easily in high voltage and high frequency work environment of radar transmitter. The development stages of the monitoring system core technology for radar transmitter experienced relay, single-chip computer, embedded industrial computer and programmable logic controller (PLC). Embedded industrial computer and PLC monitoring system is commonly used now, and this paper gives a relatively complete system of the above. Using the power monitoring method for key parameters of gate control TWT for indirect acquisition and monitoring is proposed in this paper. Provide reference for designing a reliable, stable and efficient monitoring system of radar transmitter.

Abstract: The luminance difference is one of the important factors of stereoscopic television. In this paper, according to the characteristics of stereoscopic television glasses, we use white window signal and black field signal to measure luminance difference of 3D TV. We adopt the left and right eye channel individually tested brightness. We chose the center point of stereoscopic television as measuring point. And then, we select a few of stereoscopic television as testing model. The proposed method may be helpful for the quality evaluation of stereoscopic television.

Abstract: Capacitive sensor plays an important role in electrical measuring technology. A new method of a set of parallel plate capacitor measurement circuit was proposed. The system adopted the self-excited balanced measuring method to gauge the change amount of capacitive sensor. The results show that the system has a high level of measurement accuracy and an anti-jamming capability.

Abstract: When multiple targets run through radar at the same time, the current traffic speed radars have more speed error. This paper presents an improved measuring method, provides a solution to improve time-frequency resolution. We can improve the speed resolution when adopting the algorithm proposed in the paper.

Abstract: In this paper, a novel approach based on the fluctuation analysis for the target detection in sea clutter is proposed. The self-affinity and scaling behaviors of sea clutter is analyzed by using the mean fluctuation. The q-th order normalized slope of the mean fluctuation curve is used as the characteristic parameter to describe the fractal property. The tests on the real data show that the target could be clearly distinguished from the sea clutter background with the proposed approach.

Abstract: Monitoring the variations in the upper airway (UA) for individual Obstructive Sleep Apnea/Hypopnea Syndrome (OSAHS) patients by utilizing acoustic signal analysis methods is significant to research and develop convenient equipment to overcome the invasive airway pressure measurements. It is noticeable that acoustic features like formant frequencies and power ratios had achieved good results both on diagnosing OSAHS and revealing the relationship between properties and anatomical structure. We adopted the first formant frequency (F1) and power ratio at frequency of 800 Hz (PR800) as target values to observe the tracks of them in snore episodes before an apnea/hypopnea event, which could help doctors to know the structure variations in UA for OSAHS patients. Results showed that the tracks of the two acoustic features have a good performance on demonstrating the reasonable theoretical hypothesis. If we get enough prior knowledge by large scale of experiments and practices, we can even use the tracks of F1 and PR800 to find some more detailed information of UA like observing the electrocardiogram in cardiac healthcare and monitoring.

Abstract: Condition detection of aero-engine is an important measure for the safety of engine. This paper introduced the principle of order tracking analysis, which was compared with the tradition spectral analysis, represented the advantage of this method. Finally, applied order tracking for the condition detection of aero-engine, show the validity of this method through the experiment.

Abstract: This paper presents a fault diagnosis method of BP neural network based on Levenberg-Marquardt learning algorithm. First, the use of principal component analysis to reduce the dimension of the fault sample reduced BP neural network input variables. Then use the Levenberg-Marquardt learning algorithm to adjust the network weights. Levenberg-Marquardt learning algorithm is combination of the Gauss - Newton algorithm and steepest descent algorithm. It has Gauss - Newton algorithm of local convergence and gradient descent algorithm of the global characteristic. So it has higher convergence speed, reduces the training time, to a certain extent, overcomes the problem of traditional BP network convergence speed slow and easy to fall into local minimum point. Simulation results demonstrate the correctness and accuracy of this fault diagnosis method.

Abstract: BP neural network is widely used as a multilayer feed forward neural network model. The paper puts forward a kind of adaptive learning rate algorithm and particle swarm optimization algorithm hybrid algorithm combining in order to solve the traditional BP algorithm is easy to fall into local extremum problem. So that the particle swarm optimization algorithm and adaptive learning rate algorithm are complementary. The hybrid algorithm has extensive mapping ability of neural networks and particle swarm rapid, global convergence characteristics. The simulation shows that the hybrid algorithm realizes the detection and location of analog circuit fault avoidance, has satisfied effect.