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Search Results: 1 - 10 of 59226 matches for " Jianbo Yang "
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Simulation and Experimental Study on the Atomization Character of the Pressure-Swirl Nozzle  [PDF]
Jianbo Zhao, Lijun Yang
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.24A032
Abstract: In this paper the atomization character of the pressure-swirl injector was measured by using the Phase Doppler Particle Analyzer (PDPA) in the section of 150 mm below the outlet of the orifice. The orifice diameter of the pressure-swirl injector is 0.62 mm. The atomization character includes the spray angle, the water flow rate, the Sauter mean diameter (SMD), the velocity of the particles and their distribution in the radial and the axial directions under the pressure from 1 MPa to 4.5 MPa. After that the atomization character of the pressure-swirl injector was simulated in the DPM panel. The same atomization character of the injector was calculated and compared with the experimental data. The simulation was corrected by using the experimental data which can make it accurately and the model can be used to predict and calculate the atomization character of different injectors.
Analysis and Modeling of Buck Converter in Discontinuous-Output-Inductor-Current Mode Operation  [PDF]
Jianbo Yang, Weiping Zhang, Faris Al-Naemi, Xiaoping Chen
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B163

The Buck converter with LC input filter operating in discontinuous output current mode has a high power factor with a constant duty cycle. A Buck converter in this operation mode can reduce the reverse recovery loss of the freewheeling diode thus increase the efficiency. The operation, power factor analysis and modeling of the converter are studied in this paper. Experimental results are presented to verify the theoretical predictions.

Comparisons between CRM and CCM PFC  [PDF]
Weiping Zhang, Wei Zhang, Jianbo Yang, Faris Al-Naemi
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B165

The paper presents detailed comparisons between CRM (critical conduction mode) and CCM (continuous conduction mode) control schemes used for Boost PFC converter. The two schemes are analyzed and compared under the chips of L6561 and UC 3854 which are commonly used for CRM and CCM respectively. Both schemes are based on multiplier; however, the CCM is more complex and needs more periphery components which increase the cost. The Boost PFC under CRM is easier to be implemented. Nevertheless, the variable switch frequency makes the system (including the power-stage inductor and capacitor) hard to design. It seems that the CRM PFC is more attractive in low power applications which only need to meet IEC61000-3-2 D standard. Some experiment results are also presented for the comparison.

A High Power Factor Rectifier Based on Buck Converter Operating in Discontinuous Inductor Current Mode  [PDF]
Jianbo Yang, Weiping Zhang, Faris Al-Naemi, Xiaoping Chen
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B162

By adding a suitable LC filter to the input of a Buck converter, a high-power-factor buck converter is proposed. The converter can operate in the discontinuous-output-current mode operation. A Buck converter in this operation mode features simple control as the constant duty cycle PWM used. The operation condition of the converter is studied. The validity of analysis is verified by Simulation and Experimental results.

A Single Phase Current Source PFC Converter Based on UC3854  [PDF]
Jianbo Yang, Weiping Zhang, Faris Al-Naemi, Xiaoping Chen
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B164

A novel high-power-factor Buck type converter with average current control based on UC 3854 is proposed. The input current is directly controlled by average current control scheme to deliver sinusoidal input current and to gain a high power factor. The practical results, which illustrate the proposed control philosophy, were obtained from a 120 W AC/DC Buck type converter. The power factor can reach 0.97.

Radical scavenging activity of crude polysaccharides from Camellia sinensis
Yang Fan,Yang Zhiwei,Xiao Jianbo
Archives of Biological Sciences , 2011, DOI: 10.2298/abs1103717y
Abstract: A preparation of crude polysaccharides (TPS) was isolated from Camellia sinensis by precipitation and ultrafiltration. TPS1, TPS2, and TPS3 had molecular weights of 240, 21.4, and 2.46 kDa, respectively. The radical scavenging activities of TPS were evaluated by DPPH free radical, hydroxyl radical and superoxide radical scavenging. These results revealed that TPS exhibited strong radical scavenging activity in a concentration-dependent manner. TPS3 with lowest molecular weight showed a higher radical scavenging activity.
Study of Burn Scar Extraction Automatically Based on Level Set Method using Remote Sensing Data
Yang Liu, Qin Dai, JianBo Liu, ShiBin Liu, Jin Yang
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0087480
Abstract: Burn scar extraction using remote sensing data is an efficient way to precisely evaluate burn area and measure vegetation recovery. Traditional burn scar extraction methodologies have no well effect on burn scar image with blurred and irregular edges. To address these issues, this paper proposes an automatic method to extract burn scar based on Level Set Method (LSM). This method utilizes the advantages of the different features in remote sensing images, as well as considers the practical needs of extracting the burn scar rapidly and automatically. This approach integrates Change Vector Analysis (CVA), Normalized Difference Vegetation Index (NDVI) and the Normalized Burn Ratio (NBR) to obtain difference image and modifies conventional Level Set Method Chan-Vese (C-V) model with a new initial curve which results from a binary image applying K-means method on fitting errors of two near-infrared band images. Landsat 5 TM and Landsat 8 OLI data sets are used to validate the proposed method. Comparison with conventional C-V model, OSTU algorithm, Fuzzy C-mean (FCM) algorithm are made to show that the proposed approach can extract the outline curve of fire burn scar effectively and exactly. The method has higher extraction accuracy and less algorithm complexity than that of the conventional C-V model.
Spatiotemporal patterns of the fish assemblages downstream of the Gezhouba Dam on the Yangtze River
JiangPing Tao,YuTian Gong,XiChang Tan,Zhi Yang,JianBo Chang
Science China Life Sciences , 2012, DOI: 10.1007/s11427-012-4349-0
Abstract: An explicit demonstration of the changes in fish assemblages is required to reveal the influence of damming on fish species. However, information from which to draw general conclusions regarding changes in fish assemblages is insufficient because of the limitations of available approaches. We used a combination of acoustic surveys, gillnet sampling, and geostatistical simulations to document the spatiotemporal variations in the fish assemblages downstream of the Gezhouba Dam, before and after the third impoundment of Three Gorges Reservoir (TGR). To conduct a hydroacoustic identification of individual species, we matched the size distributions of the fishes captured by gillnet with those of the acoustic surveys. An optimum threshold of target strength of 50 dB re 1 m2 was defined, and acoustic surveys were purposefully extended to the selected fish assemblages (i.e., endemic Coreius species) that was acquired by the size and species selectivity of the gillnet sampling. The relative proportion of fish species in acoustic surveys was allocated based on the composition (%) of the harvest in the gillnet surveys. Geostatistical simulations were likewise used to generate spatial patterns of fish distribution, and to determine the absolute abundance of the selected fish assemblages. We observed both the species composition and the spatial distribution of the selected fish assemblages changed significantly after implementation of new flow regulation in the TGR, wherein an immediate sharp population decline in the Coreius occurred. Our results strongly suggested that the new flow regulation in the TGR impoundment adversely affected downstream fish species, particularly the endemic Coreius species. To determine the factors responsible for the decline, we associated the variation in the fish assemblage patterns with changes in the environment and determined that substrate erosion resulting from trapping practices in the TGR likely played a key role.
Experimental Study on High Power Laser Welding of Ship Steel Plate
Yu Wang,Xichen Yang,Jianbo Lei,Chaolong Ying
Modern Applied Science , 2009, DOI: 10.5539/mas.v1n4p94
Abstract: This article puts forward adopting the fast-flow axis high power CO2 laser to weld the ship steel plate and mainly studies the influences of technical parameters to the seam. This article also analyzes and tests the welded products which are in the conditions of laser power of 8 kW, welding speed of 1m/min and focus position below 3mm of the workpiece. The results indicate that the distortion of laser welding is small, the ratio of depth and width are bigger than 2:1, and the structure is compact and has no deficiency and presents tiny martensite and few remnants austenite. Laser welding of ship steel plate can realize shaping double sides up one time with single side welding by choosing reasonable welding technical parameters. Therefore, the laser welding ship steel plate technique possesses high practical values.
Improvement in the productivity of xylooligosaccharides from rice straw by feed xylanase with ultrafiltration
Wang Fei,Guohua Hu,Xiao Jianbo,Liu Yang
Archives of Biological Sciences , 2011, DOI: 10.2298/abs1101161w
Abstract: The effective production of xylooligosaccharides (XOs) from rice straw was investigated. Rice straw contains rich hemicellulose which can be hydrolyzed by enzyme; the XOs were obtained under hydrothermal conditions. To improve the productivity of XOs, ultrafiltration was chosen to eliminate xylan in the XOs. Under optimum hydrolysis conditions (1000 IU enzyme/g, 35 0C, 10% substrate concentration, pH 6.5, 6 h), the DP was the lowest. After ultrafiltration, xylan was eliminated. On the basis of experimental data, an industrial XO production process consisting of pretreatment, enzymatic treatment and purification was designed. Using the designed process, 2.9g dry of purified XO was produced from 50g dry rice straw power.
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