Realizing the empirical mode decomposition by the adaptive stochastic resonance in a new periodical model and its application in bearing fault diagnosis

Jingling Zhang,Dawen Huang,Jianhua Yang,Hou-guang Liu,Xiaole Liu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10

We investigate a multi-frequency signal that cannot be decomposed by empirical mode decomposition directly. Moreover, this kind of signal in the noisy background cannot be decomposed successfully by the traditional stochastic resonance with bistable system yet. We propose a new method which using the empirical mode decomposition combined the adaptive stochastic resonance in a new periodical model to solve this problem. The results show that the proposed method decomposes the multi-frequency signal perfectly. Meanwhile, the general scale transformation and random particle swarm optimization algorithm are used to help obtain a better result in the process of optimization. Through using this new method, the simulation results are satisfactory. More importantly, this new method also shows good performance in the application of bearing fault diagnosis.

Ultra-high capacitance hematite thin films with controlled nanoscopic morphologies.

Liu, Jingling,Lee, Eunjik,Kim, Yong-Tae,Kwon, Young-Uk RSC Pub 2014 Nanoscale Vol.6 No.18

<P>We synthesized α-Fe2O3 (hematite) thin films with two different nanoscopic morphologies through self-assembly between a Fe-precursor and a Pluronic tri-block copolymer (F127) followed by aging and calcination. Relative humidity (RH) during the aging step of the spin-coated films was found to be critical in determining the morphologies. A network structure of nanowires 6 nm in diameter formed when the RH was 75%. The resulting nanowire hematite thin film (NW) had 150-250 nm-sized macropores. When the RH was 0%, a mesoporous hematite thin film (MP) with a wormlike pore structure and a pore size of 9 nm formed. Investigation of the electrochemical properties of these films revealed that they had very high specific capacitances of 365.7 and 283.2 F g(-1) for NWs and MPs, respectively, at a current density of 3 A g(-1) in a 0.5 M Na2SO3 electrolyte. Both of these capacitance values are considerably higher than those previously reported for hematite-based electrodes. We attributed this to the high porosity of the thin films, which enables ready access of electrolyte ions to the electrode surfaces, and their ultra-thin size, comparable to that of the depletion layer, allowing the low conductivity of hematite to be overcome. The higher capacitance of NWs than MPs is likely due to the accelerated electron transport through the crystalline nanowires in NWs.</P>

Investigation of porosity and heterojunction effects of a mesoporous hematite electrode on photoelectrochemical water splitting

Liu, Jingling,Shahid, Muhammad,Ko, Young-Seon,Kim, Eunchul,Ahn, Tae Kyu,Park, Jong Hyeok,Kwon, Young-Uk The Royal Society of Chemistry 2013 Physical chemistry chemical physics Vol.15 No.24

<P>In this paper, we report the porosity and heterojunction effects of hematite (α-Fe<SUB>2</SUB>O<SUB>3</SUB>) on the photoelectrochemical (PEC) water splitting properties. The worm-like mesoporous hematite thin films (MHFs) with a pore size of ∼9 nm and a wall thickness of ∼5 nm were successfully obtained through the self-assembly process. MHFs formed on FTO showed much better PEC properties than those of nonporous hematite thin films (NP-HF) owing to the suppression of charge recombination. The PEC data of MHFs under front and back illumination conditions indicated that the porous structure allows the diffusion of electrolyte deep inside the MHF increasing the number of holes to be utilized in the water oxidation reaction. A heterojunction structure was formed by introducing a thin layer of SnO<SUB>2</SUB> (∼15 nm in thickness) between the MHF and FTO for a dramatically enhanced PEC response, which is attributed to the efficient electron transfer. Our spectroscopic and electrochemical data show that the SnO<SUB>2</SUB> layer functions as an efficient electron transmitter, but does not affect the recombination kinetics of MHFs.</P> <P>Graphic Abstract</P><P>A highly porous hematite thin film with a heterojunction with SnO<SUB>2</SUB> shows increased usage of photo-generated holes in photoelectrochemical water splitting. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cp51053k'> </P>

Hyper-heuristic algorithm for traffic flow-based vehicle routing problem with simultaneous delivery and pickup

Wang Zhengwei,Liu Jinlong,Zhang Jingling 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.6

To address the realistic problem of seriously reducing distribution efficiency and increasing distribution cost caused by road traffic congestion, this paper constructs a time-dependent speed describing vehicle travel speed and road traffic flow by simulating the change of urban traffic flow, to establish a vehicle route problem model considering traffic flow with distribution cost and customer satisfaction as optimization objectives. To solve this problem, a hyper-heuristic algorithm based on tabu search is designed in this paper, in which the underlying search operator is selected more efficiently by a high-level heuristic strategy. In addition, the correctness of the model and the effectiveness of the algorithm are verified by conducting simulation experiments on several benchmark sets. Experiment results are shown as the travel speed of the vehicle increases, the average customer satisfaction in lc1-type instances increases to 0.94. And the impact of urban traffic changes on logistics costs and customer satisfaction is further analyzed.

Reduced Titania Films with Ordered Nanopores and Their Application to Visible Light Water Splitting

Muhammad Shahid,Seo-Yeong Choi,Jingling Liu,권영욱 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.8

We report on the photoelectrochemical properties of partially reduced mesoporous titania thin films. The fabrication is achieved by synthesizing mesoporous titania thin films through the self-assembly of a titania precursor and a block copolymer, followed by aging and calcination, and heat-treatment under a H2 (1 torr) environment. Depending on the temperature used for the reaction with H2, the degree of the reduction (generation of oxygen vacancies) of the titania is controlled. The oxygen vacancies induce visible light absorption, and decrease of resistance while the mesoporosity is practically unaltered. The photoelectrochemical activity data on these films, by measuring their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5G 100 mW cm−2 illumination, show that the three effects of the oxygen vacancies contribute to the enhancement of the photoelectrochemical properties of the mesoporous titania thin films. The results show that these oxygen deficient TiO2 mesoporous thin films hold great promise for a solar hydrogen generation. Suggestions for the materials design for improved photoelectrochemical properties are made.

Characteristics of Tower‑Level Low‑Level Jets and Their Impacts on the Urban Heat Island in Tianjin

Tingting Ju,Bingui Wu,Zongfei Li,Jingle Liu,Hongsheng Zhang 한국기상학회 2023 Asia-Pacific Journal of Atmospheric Sciences Vol.59 No.4

To date, the characteristics of the low-level jets (LLJs) that appear below 300 m, referred to in this study as tower-level LLJs(T-LLJs), have remained unidentified. The results in this study show that approximately 22% of LLJs in Tianjin appear below300 m, indicating that greater attention should be given to T-LLJs. Thus, the characteristics of T-LLJs in Tianjin are investigatedusing data obtained from a wind-profile radar and a 255-m high meteorological tower. The results show that T-LLJsfrequently occur during the transition from the warm season to the cold season and prefer to appear at night. Compared tothe LLJs that appear between 300 and 1000 m, T-LLJs exhibit distinct monthly and diurnal variations, likely attributable tospecific underlying causes. The case study suggests that the generation of T-LLJs can be partly attributed to inertial oscillation. Moreover, sensitivity tests indicate that the land‒sea thermal contrast is one of the main causes of T-LLJs, and thaturban heat islands (UHIs) exert nonnegligible influence on T-LLJs in Tianjin. In addition, since UHIs are mainly nocturnalphenomena, the impacts of nocturnal LLJs on UHIs are investigated. The results show that nocturnal LLJs contribute toenhance turbulent mixing and heat transport, which can weaken atmospheric stability near the surface. Consequently, anocturnal UHI is always weaker when it occurs concurrently with a LLJ, as opposed to occurring without a LLJ.

Reduced Titania Films with Ordered Nanopores and Their Application to Visible Light Water Splitting

Shahid, Muhammad,Choi, Seo-Yeong,Liu, Jingling,Kwon, Young-Uk Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.8

We report on the photoelectrochemical properties of partially reduced mesoporous titania thin films. The fabrication is achieved by synthesizing mesoporous titania thin films through the self-assembly of a titania precursor and a block copolymer, followed by aging and calcination, and heat-treatment under a $H_2$ (1 torr) environment. Depending on the temperature used for the reaction with $H_2$, the degree of the reduction (generation of oxygen vacancies) of the titania is controlled. The oxygen vacancies induce visible light absorption, and decrease of resistance while the mesoporosity is practically unaltered. The photoelectrochemical activity data on these films, by measuring their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5G 100 mW $cm^{-2}$ illumination, show that the three effects of the oxygen vacancies contribute to the enhancement of the photoelectrochemical properties of the mesoporous titania thin films. The results show that these oxygen deficient $TiO_2$ mesoporous thin films hold great promise for a solar hydrogen generation. Suggestions for the materials design for improved photoelectrochemical properties are made.