Coarse Alignment for SINS Using Gravity in the Inertial Frame Based on Attitude Quaternion

2012 ◽  
Vol 241-244 ◽  
pp. 413-417 ◽  
Author(s):  
Wei Dong Zhou ◽  
Hui Ma ◽  
Yu Ren Ji ◽  
Jian Li Song
Keyword(s):  
Inertial Frame ◽  
Engineering Application ◽  
Time Varying ◽  
Novel Method ◽  
Conventional Methods ◽  
Initial Attitude

In order to solve the problems of coarse alignment on swaying base of SINS, a novel method based on attitude quaternion is proposed. A decomposition of the objective initial attitude quaternion is given firstly. The time-varying parts can be derived from the quaternion update, and the invariable part can be obtained by using the integration of gravity. The problem finally becomes the Wahba’s problem. By using the FORM algorithm, the calculating process is optimized and the method can be easily used in engineering application. The final simulation verifies that the method proposed has higher accuracy than conventional methods.

scholarly journals Dynamic Beam Hopping Time Slots Allocation Based on Genetic Algorithm of Satellite Communication under Time-Varying Rain Attenuation

Electronics ◽  
2021 ◽  
Vol 10 (23) ◽  
pp. 2909
Author(s):  
Chen Zhang ◽  
Jiangtao Yang ◽  
Yong Zhang ◽  
Ziwei Liu ◽  
Gengxin Zhang
Keyword(s):  
Genetic Algorithm ◽  
Resource Allocation ◽  
Satellite Communication ◽  
Rain Attenuation ◽  
Time Varying ◽  
Dynamic Allocation ◽  
Satellite Systems ◽  
Flexible Resource ◽  
Conventional Methods ◽  
High Level

Beam hopping technology is considered to provide a high level of flexible resource allocation to manage uneven traffic requests in multi-beam high throughput satellite systems. Conventional beam hopping resource allocation methods assume constant rainfall attenuation. Different from conventional methods, by employing genetic algorithm this paper studies dynamic beam hopping time slots allocation under the effect of time-varying rain attenuation. Firstly, a beam hopping system model as well as rain attenuation time series based on Dirac lognormal distribution are provided. On this basis, the dynamic allocation method by employing genetic algorithm is proposed to obtain both quantity and arrangement of time slots allocated for each beam. Simulation results show that, compared with conventional methods, the proposed algorithm can dynamically adjust time slots allocation to meet the non-uniform traffic requirements of each beam under the effect of time-varying rain attenuation and effectively improve system performance.

scholarly journals Destination Estimation for Bus Passengers Based on Data Fusion

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Wusheng Liu ◽  
Qian Tan ◽  
Lisheng Liu
Keyword(s):  
Global Positioning System ◽  
Positioning System ◽  
Time Varying ◽  
Estimation Result ◽  
Bus Stop ◽  
Simulation Based ◽  
Global Positioning ◽  
Novel Method ◽  
Planning And Operation

The planning and operation of urban buses depend heavily on the time-varying origin-destination (OD) matrix for bus passengers. In most cities, however, only boarding information is recorded, while the alighting information is not available. This paper proposes a novel method to predict the destination of a single bus passenger based on bus smartcard data, metro smartcard data, and global positioning system (GPS) bus data. First, the attractiveness of each bus stop in a bus line was evaluated, considering the attractiveness of nearby metro stations. Then, the exploration and preferential return (EPR) model was employed to estimate the probability of a bus stop to be the alighting stop, i.e., the destination, of a passenger. The estimation result was obtained through a simulation based on the Monte Carlo (MC) algorithm. The effectiveness of our method was proved through a case study on the bus network in Shenzhen, China.

Detecting and Predicting Early Faults of Complex Rotating Machinery Based on Cyclostationary Time Series Model

2006 ◽  
Vol 128 (5) ◽  
pp. 666-671 ◽  
Author(s):  
Z. S. Chen ◽  
Y. M. Yang ◽  
Z. Hu ◽  
G. J. Shen
Keyword(s):  
Signal To Noise Ratio ◽  
Rotating Machinery ◽  
Ar Model ◽  
Model Parameters ◽  
Time Varying ◽  
Signal To Noise ◽  
Vibration Signals ◽  
Novel Method ◽  
Cyclostationary Signals ◽  
Gear Crack

Vibration signals of complex rotating machinery are often cyclostationary, so in this paper one novel method is proposed to detect and predict early faults based on the linear (almost) periodically time-varying autoregressive (LPTV-AR) model. At first the algorithms of identifying model parameters and order are presented using the higher-order cyclic-cumulant, which can suppress additive stationary noises and improve the signal to noise ratio (SNR). Then numerical simulations are done and the results indicate that this model is more effective for cyclostationary signals than the classical AR model. In the end the proposed method is used for detecting incipient gear crack fault in a helicopter gearbox. The results demonstrate that the approach can be used to detect and predict early faults of complex rotating machinery by the kurtosis of the residual signal.

Adhesion Measurements of Thin Films by Several Methods

1994 ◽  
Vol 338 ◽  
Author(s):  
Akira Kinbara ◽  
Tatsuya Banno ◽  
Ichiharu Kondo ◽  
Osamu Takenaka
Keyword(s):  
Thin Films ◽  
Ion Bombardment ◽  
Measuring Method ◽  
Interface Structure ◽  
Solid Substrates ◽  
Novel Method ◽  
Conventional Methods

ABSTRACTAdhesion of thin films to solid substrates has been measured by various methods. In addition to the traditional and the conventional methods, a novel method has been proposed. The adhesion is expressed by various units depending on the measuring method. Obtained values by typical or well known methods such as scratch, peel and pull method are expressed in terms of N, N/m and N/m2, respectively. Relation among these quantities was discussed. The interface structure between the films and the substrates was investigated by TEM, ED, EDS, etc. and was related to the adhesion. Particular attention was paid to the ion bombardment effect of the substrate on the adhesion.

scholarly journals Novel case-control observational method for assessing effectiveness of red-light cameras

2017 ◽  
Vol 44 (6) ◽  
pp. 407-416 ◽  
Author(s):  
Amal Jasem Abdulsalam ◽  
Dane Rowlands ◽  
Said M. Easa ◽  
Abd El Halim O. Abd El Halim
Keyword(s):  
Empirical Bayes ◽  
Red Light ◽  
Control Group ◽  
Cross Sectional ◽  
Specific Criterion ◽  
Red Light Cameras ◽  
Empirical Bayes Methods ◽  
Novel Method ◽  
Conventional Methods ◽  
Different Characteristics

Conventional methods for estimating the effect of an intervention suffer from selection bias, where the units that receive the treatment have different characteristics from those in the control group. This paper proposes a novel method that provides a specific criterion for selecting the control group. The method, called propensity score matching (PSM), was applied to the evaluation of red-light cameras (RLC) and its performance was compared with conventional cross-sectional and empirical Bayes methods. The application was performed using field data from the City of Ottawa involving 30 RLC intersections and 89 non-camera intersections observed for a period of 15 years. All three methods yielded fairly consistent results, indicating an increase in property damage collisions and a decrease in injury and fatal collisions. Given the strong theoretical basis of the PSM method and its ability to produce a more stable and reliable estimator, the method is recommended as a viable alternative to the conventional methods.

scholarly journals A Novel Wavelet-based Optimal Linear Quadratic Tracker for Time-varying Systems with Multiple Delays

2021 ◽  
Vol 9 (2) ◽  
pp. 418-434
Author(s):  
Iman Malmir
Keyword(s):  
Open Loop ◽  
Multiple Delays ◽  
Time Varying ◽  
Tracking Systems ◽  
Linear Quadratic ◽  
Optimal Tracking ◽  
Time Varying Systems ◽  
Optimal Linear ◽  
Novel Method ◽  
Input Variables

A novel method for solving optimal tracking control of linear quadratic time-varying systems with differentforms of time delays in state and input variables and with constraints is presented in this paper. Using the concepts of two powerful wavelets, Legendre and Chebyshev wavelets, we convert the optimal tracking problem to a static optimization one. The method is presented in a general from by which one can utilize it by other wavelets. The proposed method has the ability to solve the problems with systems of integer and fractional orders. After determining open-loop solutions of time-delay tracking systems, closed-loop suboptimal controller is designed. A highly successful wavelet-based suboptimal controller is introduced in this work. This alternative method is applied on some optimal tracking systems.

scholarly journals Heading Perception Depends on Time-Varying Evolution of Optic Flow

2018 ◽  
Author(s):  
Charlie S. Burlingham ◽  
David J. Heeger
Keyword(s):  
Flow Field ◽  
Optic Flow ◽  
Discrimination Task ◽  
Extended Period ◽  
Time Varying ◽  
Temporal Derivative ◽  
Novel Method ◽  
Considerable Support ◽  
Over Time ◽  
Phase Motion

There is considerable support for the hypothesis that perception of heading in the presence of rotation is mediated by instantaneous optic flow. This hypothesis, however, has never been tested. We introduce a novel method, termed “non-varying phase motion,” for generating a stimulus that conveys a single instantaneous optic flow field, even though the stimulus is presented for an extended period of time. In this experiment, observers viewed stimulus videos and performed a forced choice heading discrimination task. For non-varying phase motion, observers made large errors in heading judgments. This suggests that instantaneous optic flow is insufficient for heading perception in the presence of rotation. These errors were mostly eliminated when the velocity of phase motion was varied over time to convey the evolving sequence of optic flow fields corresponding to a particular heading. This demonstrates that heading perception in the presence of rotation relies on the time-varying evolution of optic flow. We hypothesize that the visual system accurately computes heading, despite rotation, based on optic acceleration, the temporal derivative of optic flow.

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