http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
IEEE 802.15.7 visible light communication: modulation schemes and dimming support
Rajagopal, S.,Roberts, R. D.,Sang-Kyu Lim IEEE 2012 IEEE communications magazine Vol.50 No.3
<P>Visible light communication refers to shortrange optical wireless communication using visible light spectrum from 380 to 780 nm. Enabled by recent advances in LED technology, IEEE 802.15.7 supports high-data-rate visible light communication up to 96 Mb/s by fast modulation of optical light sources which may be dimmed during their operation. IEEE 802.15.7 provides dimming adaptable mechanisms for flicker-free high-data-rate visible light communication.</P>
Rajagopal, Rajesh,Ryu, Kwang-Sun Pergamon Press 2018 Electrochimica Acta Vol. No.
<P><B>Abstract</B></P> <P>Nanostructured MnO<SUB>2</SUB> was synthesized using a facile hydrothermal technique with potassium permanganate as a precursor. Rare earth elements, lanthanum and cerium, were used to control the porosity of the MnO<SUB>2</SUB> nanostructures. Nanorod-, nanoflower-, nanoneedle-, and nanoneedles/nanopetal-shaped MnO<SUB>2</SUB> nanostructures were synthesized by changing the concentration of the rare earth elements. The as-synthesized MnO<SUB>2</SUB> nanorods, La – MnO<SUB>2</SUB> nanoneedles, Ce – MnO<SUB>2</SUB> nanoflowers, and La/Ce – MnO<SUB>2</SUB> nanoneedles/nanopetals were examined using a range of physico chemical characterization techniques. Scanning electron microscopy and transmission electron microscopy – energy dispersive X-ray spectroscopy confirmed the morphology of the MnO<SUB>2</SUB> nanostructures and the elemental distribution. The porous natures of the synthesized MnO<SUB>2</SUB> nanostructures were analyzed by nitrogen adsorption technique. The electrochemical behavior of the MnO<SUB>2</SUB> nanostructures was examined by cyclic voltammetry, charge – discharge and electrochemical impedance spectroscopy tests. The La/Ce – MnO<SUB>2</SUB> nanoneedles/nanopetals electrode exhibited a high specific capacitance of 825 F g<SUP>−1</SUP> at an applied current density of 10 A g<SUP>−1</SUP>. The La/Ce – MnO<SUB>2</SUB> nanoneedles/nanopetals were also mixed with 5, 10, 15 and 20 wt% of rGO nanosheets to enhance the electrochemical behavior. The 20 rGO@La/Ce – MnO<SUB>2</SUB> sample showed extraordinary electrochemical behavior; the calculated specific capacitance was 1165 F g<SUP>−1</SUP> at an applied current density of 10 A g<SUP>−1</SUP>. A 20 rGO@La/Ce – MnO<SUB>2</SUB> and activated carbon asymmetric supercapacitor coin cell device exhibited ∼93% capacitance retention after 1000 cycles. These results highlight the potential of 20 rGO@La/Ce – MnO<SUB>2</SUB> as an electrode material for supercapacitor applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Manganese oxide nanostructures were synthesized by hydrothermal process. </LI> <LI> Lanthanum and cerium used to control the porosity of manganese oxide. </LI> <LI> La/Ce mixed MnO<SUB>2</SUB> nanoneedles/nanopetals showing good electrochemical behavior. </LI> <LI> rGO mixed La/Ce – MnO<SUB>2</SUB> was prepared to improve the storage capacity. </LI> <LI> 20rGO@ La/Ce – MnO<SUB>2</SUB> electrode exhibited high specific capacitance of 1165 F g<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Rajagopal Karthikeyan,Kingni Sifeu Takougang,Kom Guillaume Honoré,Pham Viet-Thanh,Karthikeyan Anitha,Jafari Sajad 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.2
A chaotic simple jerk system (SJS) that belongs to systems with self-excited and hidden attractors is introduced in this paper. The dynamics of the proposed SJS is analytically and numerically investigated. Interestingly, the influence of the time delay on the proposed chaotic SJS is studied. In addition, the physical existence of self-excited and hidden chaotic attractors found in the proposed SJS and in the time-delayed form of SJSs (TDSJSs) are verified by using Orcard-PSpice software. Finally, chaos synchronization of identical, unidirectional, coupled, proposed chaotic TDSJSs is also reported.
Rajagopal, S.,Prabavathy, S. Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.6
In the present study, in reinforced concrete structures, beam-column connections are one of the most critical regions in areas with seismic susceptibility. Proper anchorage of reinforcement is vital to enhance the performance of beam-column joints. Congestion of reinforcement and construction difficulties are reported frequently while using conventional reinforcement detailing in beam-column joints of reinforced concrete structures. An effort has been made to study and evaluate the performance of beam-column joints with joint detailing as per ACI-352 (mechanical anchorage), ACI-318 (conventional hooks bent) and IS-456(full anchorage conventional hooks bent) along with confinement as per IS-13920 and without confinement. Apart from finding solutions for these problems, significant improvements in seismic performance, ductility and strength were observed while using mechanical anchorage in combination with X-cross bars for less seismic prone areas and X-cross bar plus hair clip joint reinforcement for higher seismic prone areas. To evaluate the performances of these types of anchorages and joint details, the specimens were assembled into four groups, each group having three specimens have been tested under reversal loading and the results are presented in this paper.
Rajagopal Reddy, V.,Janardhanam, V.,Won, Jonghan,Choi, Chel-Jong Elsevier 2017 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.499 No.-
<P><B>Abstract</B></P> <P>An Au/Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB> (CZTS)/n-GaN heterojunction (HJ) is fabricated with a CZTS interlayer and probed its chemical states, structural, electrical and frequency-dependent characteristics by XPS, TEM, <I>I</I>-<I>V</I> and <I>C</I>-<I>V</I> measurements. XPS and TEM results confirmed that the CZTS films are formed on the n-GaN surface. The band gap of deposited CZTS film is found to be 1.55eV. The electrical properties of HJ correlated with the Au/n-GaN Schottky junction (SJ). The Au/CZTS/n-GaN HJ reveals a good rectification nature with high barrier height (0.82eV) compared to the Au/n-GaN SJ (0.69eV), which suggests the barrier height is influenced by the CZTS interlayer. The barrier height values assessed by <I>I</I>-<I>V</I>, Cheung’s and Norde functions are closely matched with one other, thus the methods used here are reliable and valid. The extracted interface state density (<I>N<SUB>SS</SUB> </I>) of Au/CZTS/n-GaN HJ is lower compared to the Au/n-GaN SJ that suggests the CZTS interlayer plays an important role in the reduction of <I>N<SUB>SS</SUB> </I>. Moreover, the capacitance-frequency (<I>C</I>-<I>f</I>) and conductance-frequency (<I>G</I>-f) characteristics of SJ and HJ are measured in the range of 1kHz–1MHz, and found that the capacitance and conductance strappingly dependent on frequency. It is found that the <I>N<SUB>SS</SUB> </I> estimated from <I>C</I>-<I>f</I> and <I>G</I>-<I>f</I> characteristics is lower compared to those estimated from <I>I</I>-<I>V</I> characteristics. Analysis confirmed that Poole-Frenkel emission dominates the reverse leakage current in both SJ and HJ, probably related to the structural defects and trap levels in the CZTS interlayer.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Rajagopal, Rajesh,Ryu, Kwang-Sun THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.60 No.-
<P><B>Abstract</B></P> <P>This paper reports the synthesis of lanthanum oxide/hydroxide nanoparticle (LaNPs)-doped rGO nanosheets. The uniform distribution of LaNPs on the rGO nanosheets was confirmed by FESEM, TEM, and elemental analysis. A dramatic change in electrochemical behavior was observed by adjusting the concentration of LaNPs in rGO (LaG ratio=1:2, 1:1 and 2:1). The LaG 12 showed a better areal capacitance of 889.29Fcm<SUP>−2</SUP> than LaG 11 (428.58Fcm<SUP>−2</SUP>) and LaG 21 (260.72Fcm<SUP>−2</SUP>). Further, improved cycle stability (84% after 1000 cycles) with good impedance behavior confirms LaG 12 is a suitable electrode material for high-performance supercapacitor fabrication.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Rajagopal Reddy, V.,Janardhanam, V.,Leem, C.H.,Choi, C.J. Academic Press 2014 Superlattices and microstructures Vol.67 No.-
The temperature dependent electrical characteristics of Se/n-GaN Schottky barrier diode have been investigated in the temperature range of 130-400K in the steps of 30K. The estimated barrier height (φ<SUB>bo</SUB>) and ideality factor n are found to be 0.46eV and 3.83 at 130K, 0.92eV and 1.29 at 400K. The φ<SUB>bo</SUB> and n are found to be strongly temperature dependent and while the φ<SUB>bo</SUB> decreases and the n increase with decreasing temperature. Such behavior of φ<SUB>bo</SUB> and n is attributed to Schottky barrier inhomogeneities, explained by the assumption of Gaussian distribution of barrier heights at the metal/semiconductor interface. Experimental results revealed the existence of a double Gaussian distribution with mean barrier height values of 1.33 and 0.90eV and standard deviations (σ<SUB>o</SUB>) of 0.0289 and 0.010V, respectively. The modified ln(I<SUB>o</SUB>/T<SUP>2</SUP>)-(q<SUP>2</SUP>σ<SUB>o</SUB><SUP>2</SUP>/2k<SUP>2</SUP>T<SUP>2</SUP>) versus 10<SUP>3</SUP>/T plot gives φ<SUB>bo</SUB> and Richardson constant (A<SUP>*</SUP>) values as 1.30 and 0.88eV, 23.6 and 19.2 A/cm<SUP>2</SUP> K<SUP>2</SUP> at 400 and 130K, respectively without using the temperature coefficient of the barrier height. Further, the barrier height obtained from C-V method decreases with an increase in temperature. It is also noted that the barrier height value estimated from the C-V method is higher than that estimated from the I-V method at various temperatures. Possible explanations for this discrepancy are presented. The interface state density (N<SUB>ss</SUB>) is found to be decreased with an increasing temperature. The reverse-bias leakage current mechanism of Se/n-GaN Schottky diode is investigated. Both Poole-Frenkel and Schottky emissions are described and discussed.