Electro-transport studies of electrodeposited (Bi_1−<i>x</i>Sb_<i>x</i>)₂Te₃ nanowires

Xiao, Feng,Yoo, Bongyoung,Lee, Kyu-Hwan,Myung, Nosang V IOP Pub 2007 Nanotechnology Vol.18 No.33

<P>A wide range of (Bi<SUB>1−<I>x</I></SUB>Sb<SUB><I>x</I></SUB>)<SUB>2</SUB>Te<SUB>3</SUB> thin films and nanowires were electrodeposited from acidic tartaric–nitric baths. Initially, (Bi<SUB>1−<I>x</I></SUB>Sb<SUB><I>x</I></SUB>)<SUB>2</SUB>Te<SUB>3</SUB> thin films were electrodeposited on gold substrates to investigate the effect of the deposition potential and electrolyte composition on film composition. After these investigations, (Bi<SUB>1−<I>x</I></SUB>Sb<SUB><I>x</I></SUB>)<SUB>2</SUB>Te<SUB>3</SUB> nanowires were potentiostatically electrodeposited using polycarbonate templates as scaffolds. The deposition conditions strongly influenced the deposit composition, crystal structures, and electrical properties of the nanowires. The preferential crystal orientation of the nanowires shifted from a {110} orientation at −20 mV to a {015} orientation at −100 mV. The temperature dependent <I>I–V</I> characteristics of bundle nanowires indicated that the nanowires were semiconductors with negative temperature coefficient of resistivity. The thermal activation energies were 0.20 eV for Bi<SUB>1.8</SUB>Sb<SUB>0.1</SUB>Te<SUB>3.1</SUB> and 0.49 eV for (Bi<SUB>0.3</SUB>Sb<SUB>0.7</SUB>)<SUB>2</SUB>Te<SUB>3</SUB> nanowires, respectively.</P>

A Study on Future Design using Scenario Planning Methods

Xiao, Feng 한국디자인학회 2018 한국디자인학회 학술발표대회 논문집 Vol.2018 No.11

Opto-VLSI-based tunable single-mode fiber laser

Xiao, Feng,Alameh, Kamal,Lee, TongTak The Optical Society 2009 Optics express Vol.17 No.21

<P>A new tunable fiber ring laser structure employing an Opto-VLSI processor and an erbium-doped fiber amplifier (EDFA) is reported. The Opto-VLSI processor is able to dynamically select and couple a waveband from the gain spectrum of the EDFA into a fiber ring, leading to a narrow-linewidth high-quality tunable laser output. Experimental results demonstrate a tunable fiber laser of linewidth 0.05 nm and centre wavelength tuned over the C-band with a 0.05 nm step. The measured side mode suppression ratio (SMSR) is greater than 35 dB and the laser output power uniformity is better than 0.25 dB. The laser output is very stable at room temperature.</P>

Adsorption of phosphate using calcined Mg3–Fe layered double hydroxides in a fixed-bed column study

XiaoFeng Sun,Tsuyoshi Imai,Masahiko Sekine,Takaya Higuchi,Koichi Yamamoto,Ariyo Kanno,Shiori Nakazono 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

A granular calcined Mg3–Fe LDH adsorbent was prepared by using co-precipitation method under low super saturation condition. The characteristic of the adsorbent was analyzed by powder X-ray diffraction (XRD) and scanning electron microscope (SEM). The continuous phosphate adsorption experiments were conducted in a glass fix-bed column. The results showed an increase in bed height and initial phosphate concentration improves the phosphate adsorption capacity probably due to the longer bed height allowing a longer empty bed contact time (EBCT) between the adsorbent and the adsorbate, meanwhile the higher initial phosphate concentration provides a higher driving force for the mass transfer; however, an increase in flow rate inhibits the phosphate adsorption due to the higher flow rate reduced the interaction time of the adsorbent in solution. The bed depth service time (BDST) model was found to predict the breakthrough curve well at a 0.024 L/h flow rate and 10 mg/L initial phosphate concentration using linear regression analysis. The Clark model was found to give a best fit to experiment data under various bed height, flow rate and initial phosphate concentration, followed by the Thomas and Yoon–Nelson models using non-linear regression analysis. The reusability experiment was conducted using actual anaerobic sludge filtrate as adsorbate. The results indicated that the adsorbent still had good selectivity in an anions coexisting solution, high phosphate adsorption capacity, and acceptable desorption efficiency.

Flow ripple analysis and structural parametric design of a piston pump

Xiaofeng Wu,Chihkeng Chen,Chihwei Hong,Yafeng He 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.9

The ripple in the outlet flow from a high-pressure piston pump is caused by pressure pulses in the piston cavity when it rotates through the transition region of the valve plate. We propose a parametric design that optimizes the transition region structure of a piston pump valve plate to reduce the ripple in the outlet flow. For a high- pressure piston pump, a theoretical model of the piston cavity is developed that includes fluid compression properties and leakages. The piston pump parametric model is built using AMESIM software and a simulation is conducted. The results show that the ripple in the outlet flow is affected by the outlet pressure and the pump’s speed and by the structure of the pre-compression region of the valve plate. To minimize the ripple in the outlet flow from the piston pump, the structural parameters in the pre-compression region are optimized as the design variables using the software, ISIGHT, which integrates the piston pump parametric model in AMESIM. After optimization, the ripple in the outlet flow rate is, respectively, reduced by 37.05 %, 38.54 % and 41.04 % for outlet pressures of 200 bar, 300 bar and 400 bar. Finally, a flow ripple test experiment is performed to verify the simulation results.

Fuzzy Adaptive Control for Generic Hypersonic Vehicles with Non-Affine Aerodynamic Characteristics and Output Con-straints

Xiaofeng Zhang,Kang Chen,Wenxing Fu 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10

In this paper, a fuzzy adaptive control scheme is developed for a class of generic Hypersonic Vehicles (GHVs) subjected to non-affine aerodynamics. With the aid of the nonlinear mapping, the dynamics of the attitude tracking errors are transformed to a stochastic uncertain control system. By utilizing several specific smooth function vectors and estimating the boundaries of the uncertainties, the unknown changing uncertainties can be handled. Based on the mean-value theorem, the difficulties caused by non-affine aerodynamics can be circumvented. Meanwhile, two fuzzy logic systems (FLSs) are introduced for dealing with the aerodynamic nonlinearities. The constraints of the attitude angular tracking errors can be ensured simultaneously. Finally, simulation results demonstrated the effectiveness of the proposed algorithm.

The effect of viscosity ratio on drop pinch-off dynamics in two-fluid flow

Xiaofeng Jiang,Enle Xu,Xianliang Meng,Huai Z. Li 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.91 No.-

Drop pinch-off draws a lot of interest from scientists and engineers because of widely practical applications as well as the fascinating mechanism of finite-time singularities and self-similar behavior. This work experimentally investigates the effect of viscosity ratio on the local pinch-off mechanism of liquid drops in both air and viscous fluids, with a high-speed camera. The results show that for 56 ≤ λ ≤ 6.3 × 103 and 0.009 ≤ λ ≤ 0.061, drop pinch-off exhibits self-similar profile which is asymmetric and conical away from hmin. Drop pinch-off in air with low viscosity ratios shows either in inertial regime (I) or transition from inertial to viscous regime (I→V). But the kinetics undergoes the inertial regime (I) to inertial-viscous regime (IV) through an intermediate viscous regime (V) when the viscosity ratio becomes larger. Drop pinch-off in viscous fluids displays the transition from inertial to viscous regime (I→V). These results agree well with Eggers’s universal solution until it becomes unstable and the previous literature. The viscosity ratio indeed affects the drop pinch-off dynamics as well as interface deformation. Our experiments enrich the understanding of the interaction between the internal and external fluids on drop pinch-off behavior near the singularity point.

Suitable Drying Model for Far Infrared Drying of Taegeuk Ginseng

Xiaofeng Ning,한충수 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.4

In this study we have elucidated the suitable drying model for the far infrared drying of taegeuk ginseng. Thin layer drying tests of taegeuk ginseng were conducted at 3 temperature levels of 45, 55, and 65ºC, and 3 taegeuk ginseng size levels of large, medium, and small. Four thin layer drying models were used to estimate drying curves. The goodness-of-fit of the drying models were evaluated using the coefficient of determination (R2), root mean square error (RMSE), mean relative deviation modulus (Pe), and reduced chi-square (χ2). In the mean time, the influences of drying temperature and taegeuk ginseng size on drying behavior were also determined. The results revealed that the Page model, which can describe the far infrared drying behavior of taegeuk ginseng with a great accuracy, was the best model to fit adequately most of the drying conditions for the far infrared drying of taegeuk ginseng.

Establishment of Knowledge Base for Decision-making of Handling Process for Port Heavy Lift Cargoes

Xiaofeng Gu,Youfang Huang,Ting Fang,Wei Yan,Junliang He 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.6

Far-infrared Drying Characteristics and Quality Assessment of Ligularia fischeri

Xiaofeng Ning,한충수,조성찬,이준수,윤성수 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.suppl1

The purpose of this study was to investigate drying models and drying characteristics of Ligularia fischeri by using far-infrared drying. The far-infrared drying tests on L. fischeri were performed at air velocities of 0.6and 0.8 m/s, and drying chamber temperatures of 40, 45,and 50oC. Four thin layer drying models were used to estimate drying curves. Drying characteristics were analyzed on the basis of drying rate, color, antioxidant activity, and contents of polyphenolics and flavonoids. The goodness of the models was estimated using the coefficient of determination, the root mean square error, and the reduced chi-square. The results revealed that increases in drying temperature and air velocity caused a decrease in drying time. The Page and Thompson models were considered suitable for the far-infrared drying of L. fischeri. After drying, the antioxidant properties of L. fischeri were decreased under all drying conditions.