A Direct Measurement Method of Frequency Responses of the Smart Power IC

Hai Xu,Hee-Jun Kim,Hoon Kim IEEE 2010 IEEE transactions on instrumentation and measureme Vol.59 No.3

<P>Smart power ICs are widely used in universal input power supplies. This paper presents a detailed analysis and scheme design for real-time small-signal modeling method for smart power IC. First, in this method, the switching duty cycle is converted into a voltage output signal based on the operational characteristics of the power IC. The power IC's frequency response is then obtained by measuring the duty cycle output signal and the power IC's control input signal. The modeling system is referred to as sampling the duty cycle of the power IC with a zero-order hold output. Using least-square identification, the smart power IC's dynamic model and transfer function are synthesized from the measurement data. The results of the modeling experiment are discussed, and practical guidelines and error amplifier (EA) design examples are presented for both continuous and discontinuous conduction modes (CCM and DCM). The effectiveness and practicality are verified through experiments.</P>

Characterization of ORF39 from Helicoverpa armigera Single-nucleocapsid Nucleopolyhedrovirus, the Gene Containing RNA Recognition Motif

Xu, Hai-Jun,Liu, Yan-He,Yang, Zhang-Nv,Zhang, Chuan-Xi Korean Society for Biochemistry and Molecular Biol 2006 Journal of biochemistry and molecular biology Vol.39 No.3

In the genome of Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus, open reading frame 39 (Ha39) is the only gene predicted to encode an RNA recognition protein. Computer analysis revealed that Ha39 homologues were found in 15 NPVs, but not in GVs. Its transcripts were detected from 3 through 72 hours post infection (h p.i.) using RT-PCR and Northern blot analysis. The protein was detected in infected-cell lysates from 6 h p.i. Western blot assay of ODV and BV preparations revealed that Ha39 encodes a structural protein associated with BVs. Additionally, immunofluorescence microscopy demonstrated that the protein was present within cytoplasm in virus-infected cells, but not in the nuclear region.

Preparation and characterizations of charged PVDF membranes via composite thermally induced phase separation (C-TIPS) method

Hai-Peng Xu,Wan-Zhong Lang,Xuan Zhang,Ya-Jun Guo 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1

The charged poly(vinylidene fluoride) (PVDF) membranes were prepared by composite thermallyinduced phase separation (C-TIPS) method with perfluorosulfonic acid (PFSA) as additive. The resultsverify that the porosity, surface hydrophilicity and pure water permeation flux (JW) increase with theaddition of PFSA for the membranes. The highest JW of 507.2 1.2 L/(M2 H bar) is obtained for themembrane cast at 90 8C. Much higher casting temperature isn’t advantageous to improve JW value for thePVDF membranes. All membranes exhibit negative apparent zeta potential (zapp). The crystallinity in b phaseincreases as casting temperature increases for all PVDF membranes.

Double layered dielectric elastomer by vapor encapsulation casting for highly deformable and strongly adhesive triboelectric materials

Xu, Hai Bo,Kim, Jeong Hun,Kim, Sangtae,Hwang, Hee Jae,Maurya, Deepam,Choi, Dukhyun,Kang, Chong-Yun,Song, Hyun-Cheol Elsevier 2019 Nano energy Vol.62 No.-

<P><B>Abstract</B></P> <P>Triboelectric generators (TEG), based on contact electrification and electro-static induction, has received a significant attention because of their numerous applications. To improve the electrified surface charge density in TEG, increasing the surface area of dielectric materials or forming internal hollow structures are typically employed to increase capacitance. However, the fabrication processes of such structures are complex and time-consuming. Here, we provide a facile and cost-effective synthesis method for the porous PDMS based TEG via a novel vapor encapsulation casting (VEC). The double dielectric layer composed of the porous and dense PDMS layers are formed in-site through VEC. The thickness and the thickness ratio of the double dielectric layer can be precisely controlled by adjusting the uncured PDMS thickness and vapor penetration depth. The double dielectric layer TEG (DTEG) exhibits the improved harvesting performance because the porous dielectric layer increases the capacitance and compressibility, while the dense layer passivates the fully open pores which reduce the charging surface area as completely opening through the dielectric layer without contacting the bottom electrode. We obtain the maximum output voltage of 345 V and short circuit current of 3 μA/cm<SUP>2</SUP> from DTEG having 0.95 porous thickness ratio, resulting 330% enhancement in the power output as compared to the dense PDMS based TEG. We further investigate the performance of DTEG under various operating conditions. We also demonstrate the operation of Bluetooth distance/temperature sensors using capacitors charged by DTEG.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TEG based on the double dielectric layer composed of the sponge-like porous and flat dense elastomer is demonstrated. </LI> <LI> Facile and affordable synthesis method for the porous PDMS is provided via the novel vapor encapsulation casting. </LI> <LI> Highly deformable porous PDMS effectively enhances its capacitance under a pressure. </LI> <LI> Flat dense second layer of PDMS reduces the device impedance and improves the contact interface with an electrode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Characterization of ORF39 from Helicoverpa armigera Single-nucleocapsid Nucleopolyhedrovirus, the Gene Containing RNA Recognition Motif

( Hai Jun Xu ),( Yan He Liu ),( Zhang Nv Yang ),( Chuan Xi Zhang ) 생화학분자생물학회 2006 BMB Reports Vol.39 No.3

Microwave-Assisted Synthesis of Flower-like and Plate-like CuO Nanopowder and Their Photocatalytic Activity for Polluted Lake Water

Xu, Ling,Xu, Hai-Yan,Wang, Feng,Zhang, Feng-Jun,Meng, Ze-Da,Zhao, Wei,Oh, Won-Chun The Korean Ceramic Society 2012 한국세라믹학회지 Vol.49 No.2

Flower-like and plate-like CuO nanopowder has been successfully synthesized using a facile microwave-assisted synthetic route. The morphology and size of the final products strongly depended on microwave power. The phase, structures and morphologies of the as-prepared products were investigated in detail by BET surface area analysis, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). In addition, the chemical oxygen demand of polluted lake water was employed for characterization of these new photocatalysts. The results showed correlations between the morphology of CuO micro-crystals and their catalytic properties.

A liquid phase deposited porous flower-like HNaV6O16⋅4H2O film developed for a novel adsorbent to remove Pb2+, Cu2+, Mn2+ and Cd2+

Xu Hai-Yan,Yang Yi Cai,Li Dong-Cai,Wu Ran Ran,Wang Ai-Guo,Sun Dao-Sheng,Zhang Feng-Jun,오원춘 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.3

Heavy metal ion pollution of water resources is becoming increasingly serious, and adsorption is one of the most effective strategies for removing heavy metal ions. In the paper, hydrated hydrogen sodium vanadium oxide (HNaV 6O164H2O) fi lm developed for heavy metal ion adsorption was prepared directly via a low-temperature liquid-phase deposition approach. The prepared film shows an interesting porous flower-like morphology and has large spacing ( d = 10.87 Å). The highest adsorption capacity of the obtained HNaV 6O164H2O fi lm for Pb 2+, Cu 2+, Cd 2+ and Mn 2+ is 513 mg/g (2565 mg/m 2), 430 mg/g (2150 mg/m 2), 134 mg/g (875 mg/m 2) and 175 mg/g (670 mg/m 2), respectively. The adsorption percentage of the sample decreased from 92.2 to 86.3% after 4 cycles. The adsorption process follows the Langmuir adsorption isotherm and the pseudo second-order dynamic model, indicating that heavy metal ion adsorption by the fi lm is a single molecular layer chemical adsorption. In combination with various characterizations and comparison tests of samples after adsorption, the adsorption mechanisms include surface electrostatic attraction, complexation, and cation exchange. The results indicate that the fi lm is a potential material to remove heavy metal ions from the aqueous solution.

Prevalence of Toxoplasma gondii in Dogs in Zhanjiang, Southern China

Hai-Hai Jiang,Ming-Wei Li,Min-Jun Xu,Wei Cong,Xing-Quan Zhu 대한기생충학열대의학회 2015 The Korean Journal of Parasitology Vol.53 No.4

Toxoplasmosis, caused by Toxoplasma gondii, is a parasitic zoonosis with worldwide distribution. The present study investigated the prevalence of T. gondii in dogs in Zhanjiang city, southern China, using both serological and molecular detection. A total of 364 serum samples and 432 liver tissue samples were collected from the slaughter house between December 2012 and January 2013 and were examined for T. gondii IgG antibody by ELISA and T. gondii DNA by semi-nested PCR based on B1 gene, respectively. The overall seroprevalence of T. gondii IgG antibody was 51.9%, and T. gondii DNA was detected in 37 of 432 (8.6%) liver tissue samples. These positive DNA samples were analyzed by PCRRFLP at 3- and 5-SAG2. Only 8 samples gave the PCR-RFLP data, and they were all classified as type I, which may suggest that the T. gondii isolates from dogs in Zhanjiang city may represent type I or type I variant. This study revealed the high prevalence of T. gondii infection in dogs in Zhanjiang city, southern China. Integrated measures should be taken to prevent and control toxoplasmosis in dogs in this area for public health concern.

Experimental Identification Method for Small-Signal Analysis of Smart Power ICs

Hai Xu,Hee-Jun Kim,Won-Sup Chung IEEE 2010 IEEE transactions on industrial electronics Vol.57 No.6

<P>Smart power integrated circuits (ICs), as the combination of control and power functions on a single chip, enable the production of more miniaturized systems. This paper presents an experimental method for the small-signal frequency-response analysis of smart power ICs in switch-mode power supplies. In this method, the switching-duty-cycle output of a power IC is converted into a digital signal by using two high-speed counters during each switching period, and the power IC's control input signal is simultaneously converted into a digital signal by an analog-to-digital converter. After processing the data of the duty-cycle output and the control input, not only the transient response but also the frequency response of the power IC can be obtained. Using least square identification, the smart power IC's transfer function is finally synthesized from the measurement data. This analysis method, referred to as sampling the transient responses and frequency responses of power ICs, can efficiently provide reliable and accurate transfer functions whether the switching frequency of a power IC is jittered or frequency modulated. The experiments using different power ICs were presented herein to validate the analysis method. The results were discussed, and the effectiveness and practicality of the method were verified.</P>

Synthesis and characterization of monodisperse yttrium aluminum garnet (YAG) micro-crystals with rhombic dodecahedron

Xu, Tao,Yuan, Rui,Xu, Peng-Cheng,Pan, Dong-Jie,Yang, Woochul,Guo, Hai-Bo,Shen, Yu-Fang,Hu, Jian-Feng,Zhang, Zhi-Jun,Zhao, Jing-Tai Elsevier 2018 Journal of alloys and compounds Vol.762 No.-

<P><B>Abstract</B></P> <P>Uniform, monodisperse yttrium aluminum garnet (YAG) rhombic dodecahedron micro-crystals were synthesized using coprecipitation and hydrothermal methods. The Na<SUB>2</SUB>SO<SUB>4</SUB> as a surfactant was helpful in improving the dispersity of the crystallites and forming well-faceted, micro-sized dodecahedral YAG crystallites. The effect of the reaction time and the solvent has also been studied. The crystal growth mechanism called dissolution/crystallization was determined by analyzing the experimental and simulated results. And the specific well-developed crystal facets in the {110} family have been demonstrated by the theoretical calculation. A higher integrated emission intensity can be achieved for the YAG:Ce crystallites by improving the phase purity, morphology with better developed dodecahedrons, and dispersion. Furthermore, a rather high luminous efficacy (LE = 104.14 lm/W) for the white LED fabricated using the YAG:Ce<SUP>3+</SUP> phosphor prepared in this work was realized. The correlation between the crystal growth, morphology and luminescence properties of YAG crystallites has been established, which exhibits a great importance for the synthesis and application of mono-dispersed YAG crystallites.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Uniform and monodisperse YAG rhombic dodecahedron micro-crystals were synthesized. </LI> <LI> The growth mechanism of YAG rhombic dodecahedron was studied through experimental and computational simulation. </LI> <LI> The correlation between the crystal growth, morphology and luminescence of YAG crystallites was established. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>