Papers by Keyword: Probability Density

Abstract: The static signal is collected through the experiment, and the probability density function model is established. The static random signal noise is analyzed by frequency spectrum, power spectrum and high order spectrum analysis. It is found that the third order spectrum of the laser static signal is zero by the high order spectrum analysis. Noise signal is only to analyze on the frequency spectrum and power spectrum. The results show that the static laser signal has the characteristics of stationary Gauss random signal.

Abstract: Applying the Path Integral Solution Method, the stochastic heave motion of Truss Spar platform was studied in this paper. Taking a platform for example, probability density function of stochastic heave motion amplitude was calculated under the conditions of different wave excitations. The results show that, the changing process of probability density function in the time domain has an obvious periodicity. As the increasing of external excitation, the heave motion amplitude and speed both increases. Meanwhile, as the increasing of excitation amplitude, the probability density function of heave motion has a more pronounced periodicity.

Abstract: A method calculating the failure frequency of sensitive equipment caused by voltage sag in the monitoring period is proposed. In life and production, destruction of sensitive equipments fault caused by voltage sag is a serious power quality problem. It is a transition process that sensitive equipments fault caused by voltage sag, which is from a safe state to fault state, and it is uncertain whether it is fault in the region of the voltage tolerance curve (VTC), Probability density function is used to characterize failure state caused by voltage sag which happened in the voltage tolerance curve, and using the cumulative method to calculate sensitive equipment fault frequency through the voltage sag characteristic parameters in the period of monitoring time. Using personal computers as experiment equipments, and comparing the outcome with the result calculated by using the ITIC curve, its proved this method is superior and accurate.

Abstract: This paper proposes Bayesian statistical method to identify the video traffic by the symmetrical features and coding statistical characteristics of video calls. According to the problem of high computational complexity of the non-parametric probability density estimate method in the condition of large samples, we propose grid probability density estimation method of gird division to reduce the computational complexity. We present identification results. The experimental results indicate that that this method can effectively detect video call traffic.

Abstract: Aiming at calculation of traffic zone radius, probability density and probability distribution of trip distance were analyzed. Inner trip proportion, traffic zone radius, trip distance, space between traffic zone center and trip generator, probability of trip distance were defined as P, R, D, S and f(D) respectively. According to the relationship between D and R, three conditions were considered, i.e. D≤R, R<D≤2R and D>2R. Two models among and P and R, D, S, f(D) were established under the condition of D≤R, R<D≤2R. P was regarded as zero when D>2R. The calculating method and procedures of the traffic zone radius based on trip distance were put forward.

Abstract: This analytic investigation intends to study the nano-tunnel problem of the single electron transistor (SET), which is the most important component in the nano-electronics industry. With a combined effort of quantum mechanics and similarity parameter, the PDE equation of transient position-probability density is attained and can be applied to predict the electron’s position inside the nano tunnel. Also, appropriate initial and the boundary conditions are set up in accordance to the actual electron behavior for solving this PDE of probability density function. Thereafter, a simple, closed-form solution for the probability density is obtained and expressed in terms of the error function for a new similarity variable η. In conclusions, this is an innovative approach by using the Schrödinger equation directly to solve the nano-tunnel problem. Moreover, with the aids of this analytic position-probability-density solution, it is illustrated that the free single electron in the SET’s tunnel can only appear at some specified regions, which are defined by a dimensionless parameter η within a range of 0≤η≤2. This result can be served as a valuable design reference for setting the practical manufacture requirement.

Abstract: In this paper, a time-domain analysis method based on probability density estimation is presented for rotating machine fault detection. Generally, the vibration signals obtained from a rotating machine are time-variant since they are strongly related to the rotational speed that is not constant even in the macro steady state. Since the mostly used signal processing method, the Fourier analysis is only suitable for stationary signals, the development of the joint time-frequency analysis is demanded. Here, the probability density estimation method based on Parzen window is introduced. The probability density function of the vibration signal of the rotating machine is estimated by Parzen window, and a threshold value is predefined to decide the state of the rotating machine. By inspecting the change of the probability density of the vibration signal, the condition of the machine is monitored. Air gap eccentricity and ball cage broken bearing are considered in the experiment section, they are difficult to be detected in frequency domain while the rotating speed is not constant. The validity of the method is proved by the experiment.

Abstract: A new algorithm for tracking a maneuvering target in presence of clutter or false measurements is addressed. Due to the availability of feature or attribute information in measurement vector, a joint probability density function description of the target state and target class is given. Using the joint state-class description the predictive measurement pdf can be proven to be a Gaussian mixture distribution. A Gaussian mixture Kalman filter is used for state estimation, where maneuver detection can also be avoided. In simulation the results with three tracking algorithms are compared, which have shown that proposed method here is more effective.

Abstract: First, several widely used models of the multiaxial low-cycle fatigue life prediction based on the critical plane approach were presented in this paper, and the predicted results of these models for a medium carbon steel under the condition of multiaxial low-cycle fatigue loading were compared. Second, the stochastic expressions and probability density function curves of the fatigue performance parameters were obtained by probabilistic analysis of the medium carbon steel fatigue data. Finally, the probabilistic model of the multiaxial fatigue life prediction was simulated by Monte Carlo Method, which should provide a basis for the reliability analysis of engineering components subjected to the multiaxial complex loads.

Abstract: A method based on Bernoulli mixtures is presented in this paper for the purpose of describing the pattern of probability distribution for each of the data sets of handwritten numerals (0-9), and then classifiers are formed from these. The test samples are recognized by their posterior probabilities conditioned on every classifier. Experimental results show that our method is superior to conventional methods on robustness and accuracy.