Data Fusion Based Phase Space Reconstruction from Multi-Time Series

Rongxi Wang,Jianmin Gao,Zhiyong Gao,Xu Gao,Hongquan Jiang,Le Cui 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.6

Focused on the problem of imperfect information in the process of reconstruction from single time series, a new technology for phase space reconstruction from multi-time series based on the data fusion is proposed. Firstly, the methods Cao and mutual information are used to select the reconstruction parameters, time delay and embedded dimension; secondly, the social cognitive optimization algorithm is brought to calculate the weights for each variable; thirdly, an adaptive weighted fusion estimating method is applied for data fusion; lastly, the effectiveness of the methods mentioned in this paper is demonstrated by the analysis results of one case study of real chemical plant data sets, and the proposed methods in this paper can improve the completeness of the information of the reconstructed phase space, which is also a good foundation for further analysis of complex system.

Effects of methane concentration on hydrocarbon release during the pyrolysis of coal

Jianmin Zhang,Suoya,Hui Lian,Meishan Gao 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.2

weight-loss characteristics of Longkou lignite were studied by means of thermogravimetric analysisin methane ambience. Pyrolysis experiments of the sample coal in diferent concentrations of methane were carriedout on a tube reactor to study the characteristics of hydrocarbon released. The results show that methane can promotethe pyrolysis of lignite in a certain temperature range and the coal can also improve the pyrolysis of methane further.The influence of methane concentration on hydrocarbon release during the pyrolysis of coal is obvious. The hydrocar-bon released from the pyrolysis of lignite is intensive within the temperature range from 400oC to 50oC and thethat the release of C2, C3 and C4 has a close relationship with methane pyrolysis and proves that a synergistic effectdoes exist between the coal and methane.

Forced convection heat transfer of steam in a square ribbed channel

Jiazeng Liu,Jianmin Gao,Tieyu Gao 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.4

An experimental study of heat transfer characteristics of steam in a square channel (simulating a gas turbine blade cooling passage)with two opposite surfaces roughened by 60 deg parallel ribs was performed. The ranges of key governing parameters were: Reynolds numbers (Re) based on the channel hydraulic diameter (30000-140000), entry gauge pressure (0.2Mpa-0.5Mpa), heat flux of heat transfer surface area (5kWm-2-20kWm-2), and steam superheat (13℃-51℃). The test channel length was 1000mm, while the rib spacing (p/e)was 10, and the ratio of rib height (e) to hydraulic diameter (D) was 0.048. The test channel was heated by passing current through stainless steel walls instrumented with thermocouples. The local heat transfer coefficients on the ribbed wall from the channel entrance to the fully developed regions were measured. The semi-empirical correlation was fitted out by using the average Nusselt numbers in the fully developed region to cover the range of Reynolds number. The correlation can be used in the design of new generation of gas turbine blade cooled by steam.

The effect of cooling conditions on convective heat transfer and flow in a steam-cooled ribbed duct

Linqi Shui,Jianmin Gao,Xiaojun Shi,Jiazeng Liu,Liang Xu 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.1

This work presents a numerical and experimental investigation on the heat transfer and turbulent flow of cooling steam in a rectangularduct with 90° ribs and studies the effect of cooling conditions on the heat transfer augmentation of steam. In the calculation, the variationrange of Reynolds is from 10,000 to 190,000, the inlet temperature varies from 300°C to 500°C and the outlet pressure is from 0.5MPa to6MPa. The aforementioned wide ranges of flow parameters cover the actual operating condition of coolant used in the gas turbine blades. The computations are carried with four turbulence models (the standard k-ε, the renormalized group (RNG) k-ε, the Launder-Reece-Rodi(LRR) and the Speziale-Sarkar-Gatski (SSG) turbulence models). The comparison of numerical and experimental results reveals that theSSG turbulence model is suitable for steam flow in the ribbed duct. Therefore, adopting the conjugate calculation technique, further studyon the steam heat transfer and flow characteristics is performed with SSG turbulence model. The results show that the variation of coolingcondition strongly impacts the forced convection heat transfer of steam in the ribbed duct. The cooling supply condition of a relativelow temperature and medium pressure could bring a considerable advantage on steam thermal enhancement. In addition, comparing theheat transfer level between steam flow and air flow, the performance advantage of using steam is also influenced by the cooling supplycondition. Changing Reynolds number has little effect on the performance superiority of steam cooling. Increasing pressure wouldstrengthen the advantage, but increasing temperature gives an opposite result.

On effects of rail fastener failure on vehicle/track interactions

Xu, Lei,Gao, Jianmin,Zhai, Wanming Techno-Press 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.5

Rail support failure is inevitably subjected to track geometric deformations. Due to the randomness and evolvements of track irregularities, it is naturally a hard work to grasp the trajectories of dynamic responses of railway systems. This work studies the influence of rail fastener failure on dynamic behaviours of wheel/rail interactions and the railway tracks by jointly considering the effects of track random irregularities. The failure of rail fastener is simulated by setting the stiffness and damping of rail fasteners to be zeroes in the compiled vehicle-track coupled model. While track random irregularities will be transformed from the PSD functions using a developed probabilistic method. The novelty of this work lays on providing a method to completely reveal the possible responses of railway systems under jointly excitation of track random irregularities and rail support failure. The numerical results show that rail fastener failure has a great influence on both the wheel/rail interactions and the track vibrations if the number of rail fastener failure is over three. Besides, the full views of time-dependent amplitudes and probabilities of dynamic indices can be clearly presented against different failing status.

Effects of three drying methods on polyphenol composition and antioxidant activities of Litchi chinensis Sonn.

Si Tan,Jianmin Tang,Wenjing Shi,Zhuwei Wang,Yuanyuan Xiang,Tingwei Deng,Xiaoxu Gao,Wenfeng Li,Shengyou Shi 한국식품과학회 2020 Food Science and Biotechnology Vol.29 No.3

The aim of this study was to investigate the effects of three different drying methods, freeze drying (FD), vacuum drying (VD) and oven drying (OD) on phenolic contents and antioxidant activities of litchi fruits. 20 polyphenols were exactly identified in the litchi fruits by UPLC-QqQ/MS. Significant losses were observed in the contents of total polyphenols and antioxidant activities in the dried litchi when compared with the fresh litchi. Principle component analysis indicated that there was significant difference of phenolic component between the use of thermal drying (VD and OD) and FD. Our results suggest that FD is the optimum drying method for litchi fruits considering the content of total polyphenols and antioxidant activities.

On effects of rail fastener failure on vehicle/track interactions

Lei Xu,Jianmin Gao,Wanming Zhai 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.5

Rail support failure is inevitably subjected to track geometric deformations. Due to the randomness and evolvements of track irregularities, it is naturally a hard work to grasp the trajectories of dynamic responses of railway systems. This work studies the influence of rail fastener failure on dynamic behaviours of wheel/rail interactions and the railway tracks by jointly considering the effects of track random irregularities. The failure of rail fastener is simulated by setting the stiffness and damping of rail fasteners to be zeroes in the compiled vehicle-track coupled model. While track random irregularities will be transformed from the PSD functions using a developed probabilistic method. The novelty of this work lays on providing a method to completely reveal the possible responses of railway systems under jointly excitation of track random irregularities and rail support failure. The numerical results show that rail fastener failure has a great influence on both the wheel/rail interactions and the track vibrations if the number of rail fastener failure is over three. Besides, the full views of time-dependent amplitudes and probabilities of dynamic indices can be clearly presented against different failing status.