Abstract: This article developed an ion thruster optic system
sputter erosion depth numerical 3D model by IFE-PIC (Immersed
Finite Element-Particle-in-Cell) and Mont Carlo method, and
calculated the downstream surface sputter erosion rate of accelerator
grid; compared with LIPS-200 life test data. The results of the
numerical model are in reasonable agreement with the measured data.
Finally, we predicted the lifetime of the 20cm diameter ion thruster via
the erosion data obtained with the model. The ultimate result
demonstrated that under normal operating condition, the erosion rate
of the grooves wears on the downstream surface of the accelerator grid
is 34.6μm⁄1000h, which means the conservative lifetime until
structural failure occurring on the accelerator grid is 11500 hours.
Abstract: This paper To get the angle value with a MEMS rate
gyroscope in some specific field, the usual method is to make an
integral operation to the rate output, which will lead the error
cumulating effect. So the rate gyro is not suitable. MEMS rate
integrating gyroscope (MRIG) will solve this problem. A DSP system
has been developed to implement the control arithmetic. The system
can measure the angle of rotation directly by the control loops that
make the sensor work in whole-angle mode. Modeling the system with
MATLAB, desirable results of angle outputs are got, which prove the
feasibility of the control arithmetic.
Abstract: A novel low-cost flight simulator with the development
goals cost effectiveness and high performance has been realized for
meeting the huge pilot training needs of airlines. The simulator
consists of an aircraft dynamics model, a sophisticated designed
low-profile electrical driven motion system with a subsided cabin, a
mixed reality based semi-virtual cockpit system, a control loading
system and some other subsystems. It shows its advantages over
traditional flight simulator by its features achieved with open
architecture, software solutions and low-cost hardware.
Abstract: In this paper, we establish several oscillation criteria for the nonlinear second-order damped delay dynamic equation r(t)|xΔ(t)|β-1xΔ(t)Δ + p(t)|xΔσ(t)|β-1xΔσ(t) + q(t)f(x(τ (t))) = 0 on an arbitrary time scale T, where β > 0 is a constant. Our results generalize and improve some known results in which β > 0 is a quotient of odd positive integers. Some examples are given to illustrate our main results.
Abstract: Using Dynamic Bayesian Networks (DBN) to model genetic regulatory networks from gene expression data is one of the major paradigms for inferring the interactions among genes. Averaging a collection of models for predicting network is desired, rather than relying on a single high scoring model. In this paper, two kinds of model searching approaches are compared, which are Greedy hill-climbing Search with Restarts (GSR) and Markov Chain Monte Carlo (MCMC) methods. The GSR is preferred in many papers, but there is no such comparison study about which one is better for DBN models. Different types of experiments have been carried out to try to give a benchmark test to these approaches. Our experimental results demonstrated that on average the MCMC methods outperform the GSR in accuracy of predicted network, and having the comparable performance in time efficiency. By proposing the different variations of MCMC and employing simulated annealing strategy, the MCMC methods become more efficient and stable. Apart from comparisons between these approaches, another objective of this study is to investigate the feasibility of using DBN modeling approaches for inferring gene networks from few snapshots of high dimensional gene profiles. Through synthetic data experiments as well as systematic data experiments, the experimental results revealed how the performances of these approaches can be influenced as the target gene network varies in the network size, data size, as well as system complexity.
Abstract: In this paper, we study the oscillation of a class of second-order nonlinear neutral damped variable delay dynamic equations on time scales. By using a generalized Riccati transformation technique, we obtain some sufficient conditions for the oscillation of the equations. The results of this paper improve and extend some known results. We also illustrate our main results with some examples.
Abstract: In intensity modulated radiation therapy (IMRT)
treatment planning, beam angles are usually preselected on the basis of
experience and intuition. Therefore, getting an appropriate beam
configuration needs a very long time. Based on the present situation,
the paper puts forward beam orientation optimization using ant colony
optimization (ACO). We use ant colony optimization to select the
beam configurations, after getting the beam configuration using
Conjugate Gradient (CG) algorithm to optimize the intensity profiles.
Combining with the information of the effect of pencil beam, we can
get the global optimal solution accelerating. In order to verify the
feasibility of the presented method, a simulated and clinical case was
tested, compared with dose-volume histogram and isodose line
between target area and organ at risk. The results showed that the
effect was improved after optimizing beam configurations. The
optimization approach could make treatment planning meet clinical
requirements more efficiently, so it had extensive application
perspective.