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Research on Operational Intention Identification of Quayside Container Crane Driver
Wei Yan,Yuwei Zhao,Houjun Lu 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.1
To study intelligent auxiliary drive system of port machinery, it needs to identify operational intention of quayside container crane driver. With the background of loading and unloading process of quayside container crane, upon Hidden Markov Model, double HMM model is established. The algorithm of revised Forward-Backward is applied to calculate each likelihood of HMM in operation layer, the model of the largest likelihood is selected to be the identify result of operation behavior. After combining them to constitute the observation sequence bunch, it will be sent to the intention layer of HMM to conduct the identification of operation intention of crane driver. Finally, HMM is realized by Matlab. By means of field statistics, the basic data can be determined and effectiveness is also verified. It turns out that this model can accurately identify the operational intention of quayside container crane driver, which is of great significance for studying intelligent auxiliary drive system of port machinery.
Dynamics responses analysis in frequency domain of helical gear pair under multi-fault conditions
Lin Han,Houjun Qi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.11
This work aims to investigate dynamic characteristics of a helical gear pair under multiple faults condition, through model-based dynamic analysis. Two kinds of faults, tooth spalling and local breakages are considered. Firstly, influences of each kind of fault on meshing stiffness of gear pair with one or more faulted teeth were revealed. Then an 8 degree of freedom lumped-parameter model was developed to obtain dynamic responses. Furthermore, frequency spectrum analysis of the responses was conducted and compared with those under healthy condition. Results indicate that spalling or local breakage introduce different affects into mesh stiffness, and consequently displacement & velocity amplitudes of pinion appear with different waveforms, especially for the case only tooth breakages happen. This work could provide useful instructions for fault detection diagnosis of geared transmissions under multiple fault conditions.
Influences of friction and mesh misalignment on time-varying mesh stiffness of helical gears
Lin Han,Lixin Xu,Houjun Qi 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7
As one of the most important excitation sources of vibration, time-varying mesh stiffness of helical gear pairs need accurately calculated. Compared with spur gears, friction in helical gears is significant. This work for the first time presents an improved calculation method for the mesh stiffness of helical gears with effect of friction incorporated. Firstly, helical gear is sliced into number of pieces along its axis direction and each piece could be regarded as spur gear. Then forces applied to each piece including friction force are analyzed. Potential energy method is employed to develop time-varying mesh stiffness of each piece pair of both kinds of helical gears with different transverse and axial contact ratios. Furthermore, influences of various working conditions and misalignment on mesh stiffness are also investigated. Results indicate that effect brought by friction on total mesh stiffness should be not neglected. The reduction amount of stiffness increases with lower speed, heavier load and rougher surface. The stiffness difference between cases with and without friction is affected by gear geometry and mounting parameters like module, helix angle and mounting misalignment. This work provides an essential tool for comprehensive dynamics analysis with consideration of the relationship between stiffness and working conditions.
Packet Scheduling with QoS and Fairness for Downlink Traffic in WiMAX Networks
Nie, Wei,Wang, Houjun,Park, Jong-Hyuk Korea Information Processing Society 2011 Journal of information processing systems Vol.7 No.2
The IEEE 802.16 standard is supposed to provide a wide-range broadband wireless service, but it leaves the implementation of the wireless resource scheduler as an open issue. We have studied the scheduling problem and propose a two level scheduling (TLS) scheme with support for quality of service and fairness guarantees for downlink traffic in a WiMAX network. A central controller Base Station has a number of users, and each mobile subscriber station has different channel conditions. The same mobile subscriber station may have different service requirements at different times in the WiMAX network. Based on OPNET simulation, the results show our scheduling algorithm can increase the network throughput, maintain relative fairness, and lower delay over the round robin and weighted round robin algorithms.
Guoliang Jiang,Lei Zhang,Jinkun Wang,Houjun Zhou 한국통합생물학회 2016 Animal cells and systems Vol.20 No.5
Glioblastoma (GBM) is the most aggressive cerebral gliomas. Moreover, the overall prognosis of GBM is still little. Baicalein (BA) is a flavonoid derived from the Scutellaria baicalensis root, and has historically been used in anticancer therapies. However, its apoptosis role and related mechanisms in GBM has not yet been researched clearly. Thus, this study aimed to investigate the effects of BA on human GBM U251 cell line. The effects of BA on proliferation of U251 cells were measured by Cell Counting Kit-8 assay. Cellular apoptosis was detected by flow cytometry with annexin V-FITC/propidium iodide staining. The expression of apoptosis-related protein Bcl-2, Bax and cleaved-caspase3 was detected by quantitative real-time PCR and western blot. The expression of nuclear p65 protein, the active subunit of nuclear factor-kappa B (NF-κB), was determined by immunofluorescence and western blot. Our results showed that the viability of U251 cells significantly decreased in a time- and dose-dependent manner after treated with BA, and the apoptotic ratio of BA-treated groups was significantly higher than that of control groups. Furthermore, the expression of NF-kB-p65 in the nucleus was remarkably reduced, and the activity of NF-kB-p65 was remarkably inhibited after BA treatment. Combined treatment with a NF-kB-P65 inhibitor (QNZ) and BA resulted in the synergistic reduction of Bcl-2 expression and then increase of Bax and cleaved-caspase3 expression; and the viability of U251 cells was also inhibited. In conclusion, BA inhibits GBM cells viability and induces apoptosis via inhibit the activity of NF-kB-p65, suggesting that BA is a potential therapeutic agent for GBM.
Yanhui Liu,Ke Xu,Xiaochen Zhang,Chunhua Qi,Qingchun Lv,Houjun Feng 한국물리학회 2016 Current Applied Physics Vol.16 No.5
A simple electrochemical codeposition technique has been introduced to fabricate graphene oxide/ polypyrrole (GO/PPy) composites. To increase the adsorption of colloidal GOs at the liquideliquid interface, the organic supporting electrolyte like benzenesulfonate sodium (BS) is added in GO/pyrrole micelle solution, which does not induce the flocculation sedimentation of GO at elevated ionic strength. The narrow size distribution of GO/pyrrole/BS micelles is benefit for uniform codeposition of GO/PPy on the carbon fiber surface. Moreover, the GO nanosheets and benzensulfonate have been incorporated into composites as mixture dopants, which increased the growth orientation of PPy in electropolymerization process and result in more loose structure for ionic transportation. The composites electrodes exhibit high specific capacitance, good cyclic stability after electrochemical reduction of graphene oxide (RGO). The specific capacitance of composite electrode with low mass density still reaches 358 F/g at scan rate of 10 mV/s within an electrochemical windows of 1.0 V. The strong interaction effect between two components resists the mechanical deformation effect and exhibits only 7.1% decay at a charge/discharge current of 3 A/g after 1000 cycles. At increasing the mass density of composites to 8.4 mg/cm2, the areal capacitance of electrode almost grow linearly to 1.286 F/cm2, which is more than triple that of BS-doped PPy with the same mass density. The high capacity of the composite electrode exerts the potential applications in capacitive deionization, microbial fuel cell or even capacitive energy storage.
Tianfeng Wang,Xin Liu,Nan Jin,Dianguang Ma,Xijun Yang,Houjun Tang,Muhammad Ali,Khurram Hashmi 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
Wireless power transfer (WPT) technology has been the focus of a lot of research due to its safety and convenience. The Z-source inverter (ZSI) was introduced into WPT systems to realize improved system performance. The ZSI regulates the dc-rail voltage in WPT systems without front-end converters and makes the inverter bridge immune to shoot-through states. However, when the WPT system is combined with a ZSI, the system parameters must be configured to prevent the ZSI from entering an “accidental shoot-through” (AST) state. This state can increase the THD and decrease system power and efficiency. This paper presents a mathematical analysis for the characteristics of a WPT system and a ZSI while addressing the causes of the AST state. To deal with this issue, the impact of the system parameters on the output are analyzed under two control algorithms and the primary compensation capacitance range is derived in detail. To validate the analysis, both simulations and experiments are carried out and the obtained results are presented.