Unfalsified Adaptive Controller Design for Pilot-Aircraft System

Wei Liming,Fu Shan,Huang Dan 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

The pilot model concerning human factors introduced non-linear and time delay into the pilot-aircraft system. Unfalsified adaptive control (UAC), which is one kind of data-driven control, uses input and output data only. In UAC, supervisor is designed for selecting the best controller and controller switching algorithm is executed when necessary. In this paper, unfalsified adaptive PI controller, with linearly increasing cost level algorithm (LICLA) is used for the system. Monte Carlo simulation is taken at the end of the paper. The result shows the designed controller increase the flight performance.

Error Analysis of Multidimensional Evaluation of Pilot’s Workload Based on Objective Measures

Chan Wei,Liming Wei,Zhengxiang Cai,Yanyu Lu,Qi Wu,Dan Huang,Shan Fu 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

Evaluation of pilot’s workload during flight is a significant consideration for the safety of civil aviation. However, some errors may be brought in the measurement and the recording of objective parameters. Based on a multidimensional workload evaluation, the time delay of cardiac activity and its impacts on workload are analyzed. The results suggest that within a certain limit of error around 10s, varying from individual to individual, workload can keep the main information compared to the original workload. As the error increases, the workload may become unreliable. As a consequence, the time-delay error of cardiac activity should be controlled in a limited scale to ensure the validity and reliability of workload.

Study on Calcium Phosphate Cement for Bone Reconstruction

Liming, Hu,Changsheng, Liu,Wei, Shen,Yanfang, Gu 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.1 No.2

In this paper the prepartation of calcium phosphate salts, the setting technology, the mechanism of hydration and hardening and the biocompatibility of CPC are studied systematically. The results show that using ultrafine HAP and CaCo$_{3}$ as starting materials can greatly shorten the reaction time for the prepartation of pure TECP(only 9 hour needed) : the existence of HAP seed may cut down the setting time, bu lower the compressive strength ; the proper powder-to-liquid ratio is 4 : 1 ; the rate of hydration is comparatively rapid initially, controlled by dissolution of the reactants surfaces, however, eventually becomes diffusion nally controlled ; during the hydration and hardening process of CPC, the paste changes from viscoplasticity to viscoelasticity and to elasticity ; the initial structure is net-work fromed by Van der Waals' forces, which gradually strengthens, eventually connected by chemical bondings. The final product of CPC is acicular HAP, which has high biocompatibility including no toxicity, no carcinogenicity, no mutagenicity and no deformity. When CPC is implanted, it is highly compatible with soft tissue, and close connection between CPC and adjacent bone will occur one month later.

Study on Asymptotic Stability of Fractional Singular Systems with Time Delay

Dazi Li,Liming Wei,Tianheng Song,Qibing Jin 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.4

The stability of fractional singular systems with time delay is discussed. Considering the singularity of the system, a system is decomposed into two subsystems. Through fractional Laplacian transformation and inverse Laplacian transformation on the subsystems, the expression of the state variables in time domain is obtained. According to the characteristics of Mittag-Leffler function, some inequalities that have important influence on stability are derived. Finally, a new sufficient condition is found to make the fractional singular systems with time delay asymptotically stable when the fractional order belongs to1 < α < 2. Meanwhile, the sufficient condition is also obtained to make the system stable under the nonlinear disturbance. All processes are proved and numerical examples are provided to show the validity and feasibility of the proposed method.

Sparse Principal Component Analysis For Feature Selection of Multiple Physiological Signals from Flight Task

Dongbo Bai,Wei Liming,Wei Chan,Qi Wu,Dan Huang,Shan Fu 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

Sparse principal component analysis (SPCA) imposes extra constraints or penalty terms to the standard PCA to achieve sparsity. In this paper, we introduce an efficient algorithm for finding an effective sparse feature principal component (PC) of multiple physiological signals. The algorithm consists of two stages. In the first stage, it identifies an active index set with a desired cardinality corresponding to the nonzero entries of the PC. In the second one, it uses the power iteration method to find the best direction with respect to the active index set. Experiments on randomly generated data and multiple physiological signals datasets show that our algorithm is very fast, especially on large and sparse data sets, while the numerical quality of the solution is comparable to the state-of-art algorithm.

Quantitative Study of the Reformation of Excess Sludge by Intense Aeration Under Nutrient-poor Conditions

L Guang Wei,Chen Liming,Toda Kiyoshi,Zhang Shuting The Korean Society for Biotechnology and Bioengine 2004 Biotechnology and Bioprocess Engineering Vol.9 No.6

In the course of anaerobic storage of excess sludge, odors due to chemicals such as hydrogen sulfide are produced. These odors cause many problems. Many methods have been developed to eliminate odors, but all current methods are not only costly, but also largely inef­fective. In this paper, we investigate the process of transformation of sludge microorganism cul­tures through intense aeration under nutrient-poor conditions, in terms of the selective adjust­ment and control of microorganism culture. The aerated sludge is subsequently returned to the adjusting pool, where the microorganisms inhibit odors, thus the excess sludge itself will act as an odor inhibitor. The process can be verified in terms of viability, in that the degradation capac­ity of the sludge was maintained after the intensely-aerated sludge was returned to the treat­ment system.

Extreme Value Prediction of Traffic Loads Using the Average Conditional Exceedance Rate Method

Liping Zhang,Jianqing Bu,Liming Zhou,Wenlong Cao,Cunbao Zhao,Wei Chai 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.12

An efficient prediction of the extreme value of traffic loads is crucial for the structural design, reliability evaluation, maintenance planning, and further life-cycle cost analysis of bridges. In this work, a novel method is proposed for predicting the appropriate extreme traffic load distribution. Specifically, the average conditional exceedance rate (ACER) statistical model is estimated from the historical traffic loads which was collected through a weigh-in-motion system installed in toll stations. The basic idea of the ACER approach lies in the introduction of a cascade of conditioning approximations and the average exceedance rate to capture the dependence effects and obtain the data tail, the trend features of which are fitted with a similar Gumbel distribution function and extrapolated to the concerned level. An illustration case dealing with traffic loads using the ACER strategy is presented, the extreme value and confidence interval (CI) in any return period can be predicted by application of this approach. Furthermore, the peaks-over-threshold (POT) method based on the asymptotic extreme theory is also applied to illustrate the advantages of the ACER method. The ACER method has advantages in analyzing extreme traffic loads, with good robustness and the ability to handle extreme value prediction for different sampling strategies, it also can produce more accurate confidence intervals and predicts consistent extreme values. The study results are expected to help accurately determine traffic loads and ensure safety in bridge engineering.

Research and experimental analysis of drill string dynamics characteristics and stick-slip reduction mechanism

Jia-lin Tian,Lai Wei,Lin Yang,Liming Dai,Tangjia Zhang,He Liu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.3

Stick-slip of the drill string, as one of the critical factors affecting drilling efficiency, has always been a hot topic for experts and scholars in related fields. Serious stickslip vibration affects the well construction efficiency, drilling cost and even lead to a downhole accident. Therefore, based on the current research, this paper takes a new type of composite vibration tool as the research object, studies the working mechanism of the tool and analyzes the effect of stick-slip reduction. After establishing the multi-degree-of-freedom torsional dynamics model, we obtained the results of torsional vibration dynamics by cases analysis based on working conditions and related mechanical parameters. In addition, the results of the examples, compared with the field experimental data, verify that the vibration shock generated by the new composite tool can effectively reduce the torque fluctuation range of the system, avoid the occurrence of stick-slip phenomenon, improve the ROP (rate of penetration), and make drilling process more stable. This paper can provide reference for the optimization and development of stick-slip technology in drilling engineering, and the theoretical methods can also be developed to study the dynamics of drill string.

Response of coal rock apparent resistivity to hydraulic fracturing process

Song, Dazhao,Wang, Enyuan,Qiu, Liming,Jia, Haishan,Chen, Peng,Wei, Menghan Techno-Press 2018 Geomechanics & engineering Vol.14 No.6

In order to explore the comprehensive evaluation means of the extent of hydraulic fracturing region in coal seams, we analyzed the feasibility of detecting the response of coal rock direct current (DC) apparent resistivity to hydraulic-fracturing using Archie's theory, and conducted experimental researches on the response of DC resistivity in the hydraulic fracturing process using small-scale coal rock samples. The results show that porosity and water saturation are the two factors affecting the apparent resistivity of coal rock while hydraulic fracturing. Water has a dominant effect on the apparent resistivity of coal rock samples. The apparent resistivity in the area where water flows through is reduced more than 50%, which can be considered as a core affect region of hydraulic fracturing. Stress indirectly impacts the apparent resistivity by changing porosity. Before hydraulic fracturing, the greater axial load applied, the more serious the rupture in the samples, resulting in the greater apparent resistivity. Apparent resistivity testing is a potential regional method to evaluate the influence range of hydraulic fracturing in coal seams.

Hydrothermal Synthesis of Hierarchical Hollow Li(Ni0.8Co0.15Al0.05)O2 Microspheres for Lithium Ion Batteries

Liu Wenlong,Jiang Weiwei,Yan Chenran,Feng Wei,Wang Dongxia,Zhao Liming,Feng Tingting,Gong Feng 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.11

Li(Ni0.8Co0.15Al0.05)O2 (NCA) cathode material for lithium ion batteries is synthesized by calcining Ni–Co–Al hydroxide or carbonate hydroxide hydrate precursor, which is obtained by hydrothermal method, and the NCA cathode material is hierarchical hollow microspheres with the diameter in the range of 3–5 µm and composed of nanoflakes and/or nanowires. The effect of hydrothermal reaction time on the morphologies and the crystalline quality of the NCA cathode material is investigated on the basis of scanning electron microscopy, X-ray diffraction, and tunneling electron microscopy. The NCA cathode material shows smooth and monotonous charge/discharge characteristics, delivers a reversible capacity as 144.4 mAh/g and retains 90.4% after 50 cycles at a current density of 0.1 C between 2.5 and 4.3 V.