A Neural Network and Kalman Filter Hybrid Approach for GPS/INS Integration

Jianguo Jack Wang,Jinling Wang,David Sinclair,Leo Watts 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.1 No.-

It is well known that Kalman filtering is an optimal real-time data fusion method for GPS/INS integration. However, it has some limitations in terms of stability, adaptability and observability. A Kalman filter can perform optimally only when its dynamic model is correctly defined and the noise statistics for the measurement and process are completely known. It is found that estimated Kalman filter states could be influenced by several factors, including vehicle dynamic variations, filter tuning results, and environment changes, etc., which are difficult to model. Neural networks can map input-output relationships without apriori knowledge about them; hence a proper designed neural network is capable of learning and extracting these complex relationships with enough training. This paper presents a GPS/INS integrated system that combines Kalman filtering and neural network algorithms to improve navigation solutions during GPS outages. An Extended Kalman filter estimates INS measurement errors, plus position, velocity and attitude errors etc. Kalman filter states, and gives precise navigation solutions while GPS signals are available. At the same time, a multi-layer neural network is trained to map the vehicle dynamics with corresponding Kalman filter states, at the same rate of measurement update. After the output of the neural network meets a similarity threshold, it can be used to correct INS measurements when no GPS measurements are available. Selecting suitable inputs and outputs of the neural network is critical for this hybrid method. Detailed analysis unveils that some Kalman filter states are highly correlated with vehicle dynamic variations. The filter states that heavily impact system navigation solutions are selected as the neural network outputs. The principle of this hybrid method and the neural network design are presented. Field test data are processed to evaluate the performance of the proposed method.

Thermal Conductivity of Loess: Experimental Studies and Empirical Model

Jingjing Wang,Juntao Deng,Jianguo Zheng,Tiehang Wang,Yongtang Yu 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.2

Soil thermal conductivity is an important indicator for developing and utilizing geothermal resources. In this study, the impact of underground environmental factors on the thermal conductivity of loess was explored by studying the thermal conductivity of saturated and unsaturated loess under varying water content, dry density, and temperature using the Hot Disk thermal constant analyzer. The results show that the thermal conductivity of unsaturated undisturbed and remolded loess presents different growth trends as the water content increases. When the water content is less than 9%, the thermal conductivity of undisturbed soil increases slowly. The thermal conductivity of unsaturated loess gradually increases with temperature. When the temperature rises above 30oC, the latent heat transfer of steam gradually strengthens, accelerating the increase in thermal conductivity, which is most noticeable at intermediate saturation. However, the thermal conductivity of saturated loess rises slowly as the temperature rises. A weighted geometric average model is proposed in this study to predict the thermal conductivity of loess under temperature conditions, considering the effects of soil water content, dry density, and mineral content. The model accuracy was corroborated by the measured soil thermal conductivity and the data collected from six regions.

Design and analysis of mechanical flux‑weakening device of axial flux permanent magnet machines

Shaopeng Wang,Jiawei Lu,Bin Li,Chengcheng Liu,Youhua Wang,Gang Lei,Youguang Guo,Jianguo Zhu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.4

Due to the low inductance of an axial flux permanent magnet machine (AFPMM), the constant power speed regulation range is small. A new mechanical flux-weakening method for single-rotor single-stator AFPMMs is proposed in this paper. By installing a mechanical flux-weakening device on one side of the stator and rotating it certain angle, the speed regulation of the flux-weakening can be realized. The device is simple in structure, easy to operate, and can be operated in the process of machine operation. The validity of the device is verified by applying it to a machine. Finite-element software is used to calculate and analyze the performances of two machines with the device.

Matrix-Diffusion-Controlled Coarsening of the γ′ Phase in Waspaloy

Haiping Wang,Dong Liu,Yongzhao Shi,Jianguo Wang,Yanhui Yang,Longxiang Wang,Weidong Qin 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.6

This paper discussed the coarsening behavior of the γ′ phase in Waspaloy during heat treatment at different aging timesunder the temperatures of 960 °C and 1000 °C. The morphology of γ′ phase is obtained by scanning electron microscopyand it is measured by the software Image Pro Plus 6.0 in a variety of aging conditions. The volume fraction of the γ′ phase isdecreasing with the increase of the temperature. The radius of the γ′ phase is subject to involve the coarsening process duringaging treatment, and the coarsening rate decreases with the extension of the aging time at certain temperature. Besides,the coarsening kinetics of γ′ phase in Waspaloy is adequately characterized by the Lifshitz–Slyozov–Wagner (LSW) theorymodel as the particle size distribution and coarsening behavior show excellent agreement with the LSW model. Accordingto the experimental results and LSW model, the coarsening rate coefficients were determined to be 27.23 nm3/s and58.67 nm3/s under the aging temperature of 960 °C and 1000 °C respectively. Meanwhile, on the basis of the experimentalstatistics analysis and the LSW model, the mathematical model of the coarsening behavior of the γ′ phase in Waspaloy wasdeveloped. Mathematical model developed in this paper can be used to evaluate the coarsening process of the γ′ phase duringthermal exposure. The interfacial energy between the γ′ phase and the γ matrix was determined to be 56.04 mJ/m2 and44.27 mJ/m2 at the temperature of 960 °C and 1000 °C respectively.

Redundancy Reduction for Compressed Sensing based Random Equivalent Sampling Signal Reconstruction

Jianguo Huang,Li Wang,Yijiu Zhao 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.5

Random equivalent sampling (RES) can composite a waveform with high equivalent sampling rate from multiple low speed sampling sequences. In practical application, the performance of RES signal reconstruction would be degraded by the non-uniform distribution of sampling time. Compressed sensing (CS) theory is adopted to reconstruct RES samples, which could mitigate the inherent coherence of sampling time. However, the CS reconstruction algorithm is sensitive to the signal sparsity level that is unknown in the reconstruction stage. In this paper, we propose a redundancy reduction algorithm for CS base RES signal reconstruction that can ensure reconstruction accuracy while reducing the number of random samples. The experimental results are reported to evaluate the performance of the proposed algorithm.

A new method for regression analysis of interval-censored data with the additive hazards model

Wang Peijie,Zhou Yong,Sun Jianguo 한국통계학회 2020 Journal of the Korean Statistical Society Vol.49 No.4

The additive hazards model is one of the most popular regression models for analyzing failure time data, especially when one is interested in the excess risk or risk diference. Although a couple of methods have been developed in the literature for regression analysis of interval-censored data, a general type of failure time data, they may be complicated or inefcient. Corresponding to this, we present a new maximum likelihood estimation procedure based on the sieve approach and in particular, develop an EM algorithm that involves a two-stage data augmentation with the use of Poisson latent variables. The method can be easily implemented and the asymptotic properties of the proposed estimators are established. A simulation study is conducted to assess the performance of the proposed method and indicates that it works well for practical situations. Also the method is applied to a set of intervalcensored data from an AIDS cohort study.

Influence of Solution Concentrations on Surface Morphology and Wettability of ZnO Thin Films

Jianguo Lv,Changlong Liu,Feng Wang,Zhitao Zhou,Zhenfa Zi,Yuan Feng,Xiaoshuang Chen,Feng Liu,Gang He,Shiwei Shi,Xueping Song,Zhaoqi Sun 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.2

ZnO thin films were grown on silicon substrates using a hydrothermal method. The XRD patterns show that all of the peaks can be attributed to the wurtzite structures of ZnO. The TC value of (002) plane and average crystal size increase first and then decrease with the increase of solution concentration. SEM and AFM results show that many dense hexagonal cylinder particles have been observed on the surface of the thin films, which grown at 0.08 and 0.10 mol/L. The surface roughness of the thin films deposited at 0.06,0.08, 0.10, and 0.12 mol/L are 24.5, 38.3, 32.0, and 39.4 nm, respectively. Surface wettability results show that the preferential orientation along c-axis and surface roughness contribute significantly to the hydrophobicity. The reversible switching between hydrophobicity and hydrophilicity is related to the synergy of the transition of wetting model, surface crystal structure, and surface roughness.

Facile Synthesis of Zn1-xCuxO Nanorods with a Very Broad Visible Band

Jianguo Lv,Changlong Liu,Wanbing Gong,Zhenfa Zi,Xiaoshuang Chen,Kai Huang,Feng Liu,Tao Wang,Gang He,Xueping Song,Zhaoqi Sun 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.5

Zn1-xCuxO nanorods with different Cu concentrations are prepared by a hydrothermal method. Bent and aggregated nanorods are obtained, which is attributed to centripetal surface tension of the evaporation and coagulation processes of the water film on the ZnO nanorods. The broad visible band consists of one violet, three blue,and one green emission. The violet emission is due to the transition of electrons from zinc interstitial (Zni)levels to the valance band. The three blue emissions may be attributed to the transition from extended Zni levels, which are slightly below the simple Zni level, to the valance band. The change of the green emission may be the result of competition between oxygen vacancies (VO) and zinc vacancies (VZn).

Age-dependent renal expression of acid-base transporters in neonatal ureter obstruction

Wang, Guixian,Topcu, Sukru Oguzkan,Ring, Troels,Wen, Jianguo,Djurhuus, Jens Christian,Kwon, Tae-Hwan,Nielsen, Søren,Frøkiær, Jørgen Springer-Verlag 2009 Pediatric nephrology Vol.24 No.8

Dynamic analysis of a cylindrical boom based on Miura origami

Jianguo Cai,Ya Zhou,Xinyu Wang,Yixiang Xu,Jian Feng 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.5

The dynamic behavior of the deployment and folding process of a foldable boom based on the Miura origami pattern is investigated in this paper. Firstly, mechanical behavior of a single storey during the motion is studied numerically. Then the deployment and folding of a multi-storey boom is discussed. Moreover, the influence of the geometry parameters and the number of Miura-ori elements n on the dynamic behavior of the boom is also studied. Finally, the influence of the imperfection on the dynamic behavior is investigated. The results show that the angles between the diagonal folds and horizontal folds will have great effect on the strains during the motion. A bistable configuration can be obtained by choosing proper fold angles for a given multi-storey boom. The influence of the imperfection on the folding behavior of the foldable mast is significant.