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111.
Ramachandran K. Tripathi V.K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(2):141-144
Near the critical layer, a large-amplitude laser beam creates a transverse plasma channel due to the ponderomotive force. The axis of the channel is normal to the ambient density gradient. Inside the channel, the laser beam decays into counter-propagating ion acoustic and Langmuir waves. A nonlocal theory of the process is developed for a parabolic density profile. The growth rate of the instability is significantly reduced due to the nonlocal effects 相似文献
112.
Bolam R.J. Ramachandran V. Coolbaugh D. Watson K.M. 《Electron Devices, IEEE Transactions on》2003,50(4):941-944
In this paper, we discuss the electrical characteristics and reliability of UV transparent Si/sub 3/N/sub 4/ metal-insulator-metal (MIM) capacitors. We examine film thicknesses in the range of 55 to 25 nm with capacitance densities from 1.2 ff//spl mu/m/sup 2/ to 2.8 ff//spl mu/m/sup 2/, respectively, for single MIM capacitors. A new approach for projecting the dielectric reliability of these films extends the limits of maximum operating voltage. Accounting for temperature acceleration and area scaling, the projected lifetimes can be met for a wide range of operating conditions. 相似文献
113.
S. Ramachandran M.F. Yan E. Monberg F.V. Dimarcello P. Wisk S. Ghalmi 《Photonics Technology Letters, IEEE》2003,15(11):1561-1563
We demonstrate resonant grating couplers with the broadest bandwidth (565 nm) reported to date, using microbend gratings in dispersion-optimized few-mode fibers. Control of modal dispersion enables the demonstration of spectrally flat (< 0.25-dB ripple) coupling. This enables a compact (1 cm), broad-band (110 nm) variable optical attenuator, which is highly cost-effective, since device assembly simply involves pressing an as-drawn fiber between two corrugated blocks. 相似文献
114.
In-fiber devices enable a vast array of critical photonic functions ranging from signal conditioning (amplification, dispersion control) to network management (add/drop multiplexers, optical monitoring). These devices have become mainstays of fiber-optic communication systems because they provide the advantages of low loss, polarization insensitivity, high reliability, and compatibility with the transmission line. The majority of fiber devices reported to date are obtained by doping, designing, or writing gratings in the core of a single-mode fiber (SMF). Thus, these devices use the fiber only as a platform for propagating light-the device effect itself is due to some extraneously introduced material or structure (dopants for amplification, gratings for phase matching, etc.) There exists another, relatively less explored degree of freedom afforded by fibers-the ability to copropagate more than one mode. Each mode may have a uniquely defined modal dispersion and propagation characteristic. In this paper, we will describe the variety of fiber devices enabled by few-mode fibers-fibers that typically support two to four modes with suitably tailored dispersive properties. We will show that the unique dispersive properties of various modes, in conjunction with the ability to couple between them with gratings, leads to devices that offer novel solutions for dispersion compensation, spectral shaping, and polarization control, to name a few. 相似文献
115.
In this correspondence, time-frequency distribution (TFD) kernels are obtained using finite impulse response (FIR) filter design methods, namely, the windowing method and the equiripple approximation method based on Chebyshev criterion. It is shown that the class of the window-designed kernels are simple to obtain and can handle most time-varying environments 相似文献
116.
Ramachandran N.P. Dinc H. Karsilayan A.I. 《Solid-State Circuits, IEEE Journal of》2003,38(6):1051-1058
An analog line driver for video applications is presented. Utilizing a class-AB error amplifier structure, the design achieved 1.2-V peak-to-peak output swing with better than 42-dB linearity for frequencies up to 5 MHz. An adaptive tuning scheme for output impedance matching using peak detection is used to provide uniform performance across line impedance variations. The circuit is designed in AMI 0.5-/spl mu/m CMOS technology and has a tuning range of 70-180 /spl Omega/ with a power consumption of about 26.4 mW at 75-/spl Omega/ load. 相似文献
117.
We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented
states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among
the spinors in the coupled state. 相似文献
118.
Nagarajan Amirtha Seshaiyer Viswanathan Ramachandran Ganesan 《Monatshefte für Chemie / Chemical Monthly》1984,115(1):35-43
The kinetics of the addition of iodine monochloride (ICl) to some vinyl compounds in nitrobenzene solvent was investigated. In all cases the reaction follows second order dependence on ICl and first order on the substrate, making the total order three. Rate constants were measured for each substrate at 20°, 30°, 40° and 50°C.Arrhenius plots were made from which activation energies were evaluated. Other kinetic and thermodynamic parameters are reported. A suitable mechanism is proposed for the reaction and based on this, the various parameters are discussed. Solvent effects are discussed and the data with nitrobenzene and acetic acid solvents are compared.
Kinetik und Mechanismus der Addition vonICl zu einigen Alkenen in Nitrobenzol als Lösungsmittel. Effekt der Polarität des Lösungsmittels
Zusammenfassung Die Kinetik der Addition von ICl zu einigen Vinylverbindungen in Nitrobenzol als Lösungsmittel wurde untersucht. In allen Fällen ist die Reaktion von zweiter Ordnung hinsichtlich ICl und von erster Ordnung hinsichtlich des Substrats, d. h. mit einer Gesamtordnung von drei. Geschwindigkeitskonstanten wurden für jedes Substrat bei 20°, 30°, 40° und 50°C gemessen. AusArrhenius-Diagrammen wurden Aktivierungsenergien ermittelt und auch andere kinetische und thermodynamische Parameter wurden bestimmt. Ein Mechanismus wird vorgeschlagen, wobei die verschiedenen Parameter diskutiert werden. Lösungsmitteleffekte werden ebenfalls diskutiert und die Daten mit Nitrobenzol und Essigsäure als Lösungsmittel miteinander verglichen.相似文献
119.
120.
S Ramachandran 《Journal of Combinatorial Theory, Series B》1978,24(3):362-364
A square (cube) coloring of a graph is an assignment of colors to its points so that no two points of distance less than or equal to two (three) get the same color. We prove that planar graphs with a square or cube root are four colorable using a square (cube) coloring of their square (cube) root. 相似文献