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An E-capless AC-DC CRM Flyback LED Driver with Variable On-time Control
Yao, Kai,Bi, Xiaopeng,Yang, Siwen The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2
LED is a promising new generation of green lighting with the advantages of high efficiency, good optical performance, long lifetime and environmental friendliness. A pulsating current can be used to drive LEDs. However, current with a high peak-to-average ratio is unfavorable for LEDs. A novel control scheme for the ac-dc critical conduction mode (CRM) flyback LED driver is proposed in this paper. By using the input voltage, output voltage and average output current to control the turn-on time of the switch, the peak-to-average ratio of the output current can be reduced. The operation principle is analyzed and an implementation circuit is put forward. Experimental results show the effectiveness of the proposed scheme.
Yao Sadaiou Sabas Barima,Djedoux Maxime Angaman,Kobenan Pierre N`gouran,N`guessan Achille Koffi,Fidele Zamble Tra Bi,Roeland Samson 대한환경공학회 2016 Environmental Engineering Research Vol.21 No.2
In most African urban areas, Particulate Matters (PM) concentration exceeds by far the WHO limits. In these areas, plants can play a key role in removing particles. In this study, we evaluated three ornamental species (Jatropha interrigima, Ficus benjamina, Barleria prionitis) used in Abidjan Ivory Coast). Leaf-encapsulated saturation isothermal remnant magnetisation (SIRM) were measured and the relationship between PM captured and leaf wettability were done. The sampling were performed at roadsides and Parks. Firstly, Leaf-encapsulated and total leaf SIRM were quantified and the wettability was determined by drop contact angles (DCA). Secondly, the relationship between leaf SIRM and wettability was found. Results showed that leaf SIRM was two to ten times higher at roadsides than in Parks. Total leaf SIRM was also higher on mature leaves in Main roads suggesting a particle accumulation in leaves over time especially in waxy species (Ficus benjamina). This species encapsulated other than 20% of total leaf SIRM. All tested species were highly-wettable (40° < DCA < 90°). Thus, Jatropha interrigima with its leaf trichomes and F. benjamina with its leaf waxes were more wettable. A significantly positive correlation was found between wettability intensity and leaf SIRM.
Xiling Yao,Seung Ki Moon,Guijun Bi 한국CDE학회 2017 Journal of computational design and engineering Vol.4 No.2
Additive manufacturing(AM)techniquesareidealforproducingcustomizedproductsduetotheirhighdesign flexibility. Despitethepreviousstudies onspecific additivemanufacturedcustomizedproductssuchasbiomedicalimplantsandprostheses,thesimultaneousoptimizationofcomponents, materials,AMprocesses,anddimensionsremainsachallenge.Multidisciplinarydesignoptimization(MDO)isaresearchareaofsolving complexdesignproblemsinvolvingmultipledisciplineswhichusuallyinteractwitheachother.Theobjectiveofthisresearchistoformulate andsolveanMDOprobleminthedevelopmentofadditivemanufacturedproductscustomizedforvariouscustomersindifferentmarket segments.Threedisciplines,i.e.thecustomerpreferencemodeling,AMproductioncosting,andstructuralmechanicsareincorporatedinthe MDOproblem.Theoptimalselectionsofcomponents,materials,AMprocesses,anddimensionalparametersaresearchedwiththeobjectivesto maximizethefunctionalityutility,matchindividualcustomers’ personal performancerequirements,andminimizethetotalcost.Amulti-objective geneticalgorithmwiththeproposedchromosomeencodingpatternisappliedtosolvetheMDOproblem.Acasestudyofdesigningcustomized trans-tibialprostheseswithadditivemanufacturedcomponentsispresentedtoillustratetheproposedMDOmethod.Clustersofmulti-dimensional Pareto-optimaldesignsolutionsareobtainedfromtheMDO,showingtrade-offsamongtheobjectives.Appropriatedesigndecisioncan bechosenfromtheclustersbasedonthemanufacturer'smarketstrategy.
An E-capless AC-DC CRM Flyback LED Driver with Variable On-time Control
Kai Yao,Xiaopeng Bi,Siwen Yang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2
LED is a promising new generation of green lighting with the advantages of high efficiency, good optical performance, long lifetime and environmental friendliness. A pulsating current can be used to drive LEDs. However, current with a high peak-to-average ratio is unfavorable for LEDs. A novel control scheme for the ac-dc critical conduction mode (CRM) flyback LED driver is proposed in this paper. By using the input voltage, output voltage and average output current to control the turn-on time of the switch, the peak-to-average ratio of the output current can be reduced. The operation principle is analyzed and an implementation circuit is put forward. Experimental results show the effectiveness of the proposed scheme.
Xiling Yao,문승기,Bing Yang Lee,Guijun Bi 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.12
Selective laser melting (SLM) is a powder-bed fusion additive manufacturing process that fabricates metallic parts in a layer-by-layer manner. IN718 is a nickel-based austenitic (γ) superalloy with broad applications in aerospace, chemical, and nuclear industries. In this study, fully-dense IN718-matrix composite reinforced by TiC nanoparticles were fabricated in-situ by SLM. As-built and heattreated IN718/TiC nanocomposite was compared against pure IN718 in terms of microstructures and tensile properties. Columnar and cellular microstructure morphologies in as-built pure IN718 and IN718/TiC nanocomposite were demolished by heat treatment. Microstructure refining and grain boundary dislocation pinning effect of TiC nanoparticles improved the tensile strength of as-built IN718/TiC nanocomposite. In both as-built IN718/TiC and pure IN718, γ and Laves phase are the major constituents while the other precipitates were suppressed by rapid solidification in SLM. Heat treatment dissolved Laves precipitates and grew γ'/γ'', δ, and MC/ M23C6 carbides that strengthened both pure IN718 and IN718/TiC nanocomposite. In heat-treated IN718/TiC, the TiC nanoparticles and M23C6 carbides degenerated from TiC counteracted the deficiency of δ precipitates. Therefore, heat-treated IN718/TiC nanocomposite had similar tensile strength but lower ductility than heat-treated pure IN718.
Effect of phosphorus deficiency on erythrocytic morphology and function in cows
Ziwei Zhang,Mingyu Bi,Jie Yang,Haidong Yao,Zhonghua Liu,Shiwen Xu 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.3
The aim of this study was to evaluate the influence of phosphorus (P) deficiency on the morphological and functional characteristics of erythrocytes in cows. Forty Holstein-Friesian dairy cows in mid-lactation were randomly divided into two groups of 20 each and were fed either a low-P diet (0.03% P/kg dry matter [DM]) or a control diet (0.36% P/kg DM). Red blood cell (RBC) indices results showed RBC and mean corpuscular hemoglobin decreased while mean corpuscular volume increased significantly (p < 0.05) in P-deficient cows. Erythrocyte morphology showed erythrocyte destruction in P-deficient cows. Erythrocytes’ functional characteristics results showed total bilirubin and indirect bilirubin concentrations and aspartate transaminase and alanine transaminase activity levels in the serum of P-deficient cows were significantly higher than those in control diet-fed cows. Activities of superoxide dismutase and glutathione peroxidase in erythrocytes were lower, while the malondialdehyde content was greater, in P-deficient cows than in control diet-fed cows. Na+/K+-ATPase and Mg2+-ATPase activities were lower in P-deficient cows than in control diet-fed cows; however, Ca2+-ATPase activity was not significantly different. The phospholipid composition of the erythrocyte membrane changed and membrane fluidity rigidified in P-deficient cows. The results indicate that P deficiency might impair erythrocyte integrity and functional characteristics in cows.
A False Positive 18F-FDG PET/CT Scan Caused by Breast Silicone Injection
Chao-Jung Chen,Bi-Fang Lee,Wei-Jen Yao,Pei-Shan Wu,Wen-Chung Chen,Shu-Lin Peng,Nan-Tsing Chiu 대한영상의학회 2009 Korean Journal of Radiology Vol.10 No.2
We present here the case of a 40-year-old woman with a greater than 10 year prior history of bilateral breast silicone injection and saline bag implantation. Bilateral palpable breast nodules were observed, but the ultrasound scan was suboptimal and the magnetic resonance imaging showed no gadoliniumenhanced tumor. The 18F-FDG PET/CT scan showed a hypermetabolic nodule in the left breast with a 30% increase of 18F-FDG uptake on the delayed imaging, and this mimicked breast cancer. She underwent a left partial mastectomy and the pathology demonstrated a siliconoma.