Study on Vibrational Distribution of D_2 Molecules in Edge Plasmas

The molecules's behavior in edge plasma is very important in understanding the phenomena near plasma-facing materials. In this paper, various processes of deuterium molecules are discussed and most recent data are applied in the evaluation of molecules' vibrational excitation. For the excitation of the molecules to triplet states, complete sets of vibrationally-resolved cross sections are not available from the literatures. Semi-classical Gryzinski method is used to calculate these cross sections and rate coefficients. Finally, The vibrational distribution of deuterium molecules is calculated by applying a quasi-steady state model for the balance of the vibrational populations. The dependence on the plasma parameters is discussed.

Improved Calculation of Vibrational Energy Levels in F2 Molecule using the RKR Method

The potential energy curves of the ground state X2∑＋g of the fluorine molecule have been accurately reconstructed employing the Ryderg-Klein-Rees （RKR） method extrapolated by a Hulburt and Hirschfeler potential function for longer internuclear distances. Solving the corresponding radial one-dimensional Schr？dinger equation of nuclear motion yields 22 bound vibrational levels above v=0. The comparison of these theoretical levels with the experimental data yields a mean absolute deviation of about 7.6 cm^-1 over the 23 levels. The highest vibrational level energy obtained using this method is 13308.16 cm？1 and the relative deviation compared with the experimental datum of 13408.49 cm^-1 is only 0.74%. The value from our method is much closer and more accurate than the value obtained by the quantum mechanical ab initio method by Bytautas. The reported agreement of the vibrational levels and dissociation energy with experiment is contingent upon the potential energy curve of the F2 ground state.

Electron-Vibrational Energy Exchange in Nitrogen-Containing Plasma:a Comparison Between an Analytical Approach and a Kinetic Model

This paper investigates the electron-vibrational（e-V）energy exchange in nitrogencontaining plasma,which is very efficient in the case of gas discharge and high speed flow.Based on Harmonic oscillator approximation and the assumption of the e-V relaxation through a continuous series of Boltzmann distributions over the vibrational states,an analytic approach is derived from the proposed scaling relation of e-V transition rates.A full kinetic model is then investigated by numerically solving the state-to-state master equation for all vibrational levels.The analytical approach leads to a Landau-Teller（LT）-type equation for relaxation of vibrational energy,and predicts the relaxation time on the right order of magnitude.By comparison with the kinetic model,the LT-type equation is valid in typical electron temperatures in gas discharge.However,the analytical approach is not capable of describing the vibrational distribution function during the e-V process in which a full kinetic model is required.

Practical Pattern Recognition System for Distributed Optical Fiber Intrusion Monitoring Based on Ф-COTDR

At present, the demand for perimeter security system is in-creasing greatly, especially for such system based on distribut-ed optical fiber sensing. This paper proposes a perimeter se-curity monitoring system based on phase-sensitive coherentoptical time domain reflectometry(Ф-COTDR) with the practi-cal pattern recognition function. We use fast Fourier trans-form(FFT) to exact features from intrusion events and a multi-class classification algorithm derived from support vector ma-chine(SVM) to work as a pattern recognition technique. Fivedifferent types of events are classified by using a classifica-tion algorithm based on SVM through a three-dimensional fea-ture vector. Moreover, the identification results of the patternrecognition system show that an identification accurate rate of92.62% on average can be achieved.

Quasi-classical trajectory study of the stereodynamics of a Ne+H_2^+→NeH^++H reaction

We have carried out a quasi-classical trajectory calculation for the reaction ofNe ＋ H2＋ （v = 0, j = 1） → NeH＋ ＋ H on the ground state （12AI） using the LZHH potential energy surface constructed by L/i et al. [Lu S J, Zhang P Y, Han K L and He G Z 2010 J. Chem. Phys. 132 014303]. Differential cross sections at many collision energies indicate that the reaction is dominated by forward-scattering. In addition, the Nell＋ product shows rotationally hot and vibrationally cold distributions. Stereodynamical results indicate that the products are strongly polarized in the direction perpendicular to the scattering plane and that the products rotate mainly in planes parallel to the scattering plane.

Dynamics of the CH4+ O(~3 P) → CH_3(ν= 0) + OH(■= 0) reaction

The dynamics of the ground-state reaction of CH4＋ O（~3P） → CH3（ν = 0） ＋ OH（ ν= 0） have attracted a great deal of attention both theoretically and experimentally. This rapid communication represents extensive quasi-classical trajectory calculations of the vibrational distributions on a unique full-dimensional ab initio potential energy surface for the title reaction, at the collision energy of relevance to previous crossed molecular beam experiments. The surface is constructed using the all electrons coupled-cluster singles and doubles approach plus quasi-perturbative triple excitations with optimized basis sets. A modified Shepard interpolation method is also employed for the construction. Good agreement between our calculations and the available experimental results has been achieved, opening the door for accurate dynamics on this surface.

Vacuum Ultraviolet Photodissociation Dynamics of N_(2)O+hν→N_(2)(X^(1)Σg+)+O(^(1)S0) in the Short Wavelength Tail of D^(1)Σ+Band

Vacuum ultraviolet photodissociation dynamics of N2O+hν→N2(X^(1)Σg+)+O(^(1)S0)in the short wavelength tail of D^(1)Σ+band has been investigated using the time-sliced velocity-mapped ion imaging technique by probing the images of the O(^(1)S0)photoproducts at a set of photolysis wavelengths including 121.47 nm,122.17 nm,123.25 nm and 123.95 nm.The product total kinetic energy release distributions,vibrational state distributions of the N2(X^(1)Σg+)photofragments and angular anisotropy parameters have been obtained by analyzing the raw O(^(1)S0)images.It is noted that additional vibrationally excited photoproducts(3≤v≤8)with a Boltzmann-like feature start to appear except the non-statistical component as the photolysis wavelength decreases to 123.25 nm,and the corresponding populations become more pronounced with decreasing of the photolysis wavelength.Furthermore,the vibrational state specific anisotropy parameterβat each photolysis wavelength exhibits a drastic fluctuation nearβ=1.75 at v<8,and decreases to a minimum as the vibrational quantum number further increases.While the overall anisotropy parameterβfor the N2(X^(1)Σg+)+O(^(1)S0)channel presents a roughly monotonical increase from 1.63 at 121.47 nm to 1.95 at 123.95 nm.The experimental observations suggest that there is at least one fast nonadiabatic pathway from initially prepared D^(1)Σ+state to the dissociative state with bent geometry dominating to generate the additional vibrational structures at high photoexcitation energies.

Quasiclassical calculation of the chemical reaction Ba＋C3HTBr → BaBr＋C3H7

The quasi-classical trajectory （QCT） method based on the extended London-Eyring-Polanyi Sato potential en- ergy surface is used to investigate the product vibrational distribution, angular distribution and angle-resolved kinetic distribution of the reaction Ba＋C3HTBr→BaBr＋C3H7 at 2.58 kcal/mol. The calculated results show that the product BaBr vibrational distribution is quite hot, the vibrational population peaks are located at v = 12, and the angular product distribution tends to backward scattering. The calculated angle-resolved kinetic distribution shows that the kinetic distribution is obviously related to angle. The QCT results are always qualitatively acceptable and sometimes even quantitatively.

Path integral Monte Carlo study of(H_2)_n@C_(70)(n = 1, 2, 3)

The path integral Monte Carlo(PIMC) method is employed to study the thermal properties of C70 with one, two,and three H2 molecules confined in the cage, respectively. The interaction energies and vibrationally averaged spatial distributions under different temperatures are calculated to evaluate the stabilities of(H2)n@C70(n = 1, 2, 3). The results show that(H2)2@C70is more stable than H2@C70. The interaction energy slowly changes in a large temperature range,so temperature has little effect on the stability of the system. For H2@C70and(H2)2@C70, the interaction energies keep negative; however, when three H2 molecules are in the cage, the interaction energy rapidly increases to a positive value.This implies that at most two H2 molecules can be trapped by C70. With an increase of temperature, the peak of the spatial distribution gradually shifts away from the center of the cage, but the maximum distance from the center of H2 molecule to the cage center is much smaller than the average radius of C70.

Feature Extraction and Identification in Distributed Optical-Fiber Vibration Sensing System for Oil Pipeline Safety Monitoring

High sensitivity of a distributed optical-fiber vibration sensing （DOVS） system based on the phase-sensitivity optical time domain reflectometry （Ф-OTDR） technology also brings in high nuisance alarm rates （NARs） in real applications. In this paper, feature extraction methods of wavelet decomposition （WD） and wavelet packet decomposition （WPD） are comparatively studied for three typical field testing signals, and an artificial neural network （ANN） is built for the event identification. The comparison results prove that the WPD performs a little better than the WD for the DOVS signal analysis and identification in oil pipeline safety monitoring. The identification rate can be improved up to 94.4%, and the nuisance alarm rate can be effectively controlled as low as 5.6% for the identification network with the wavelet packet energy distribution features.

Galloping Vibration Monitoring of Overhead Transmission Lines by Chirped FBG Array

A distributed online fiber sensing system based on the phase-sensitive optical time domain reflectometer(Φ-OTDR)enhanced by the drawing tower fiber Bragg grating(FBG)array is presented and investigated experimentally for monitoring the galloping of overhead transmission lines.The chirped FBG array enhanced Φ-OTDR sensing system can be used to measure the galloping behavior of the overhead transmission lines(optical phase conductor or optical power ground wire),which are helpful for monitoring the frequency response characteristics of the ice-induced galloping,evaluating the motion tendencies of these cables,and avoiding the risk of flashover during galloping.The feasibility of the proposed online monitoring system is demonstrated through a series of experiments at the Special Optical Fiber Cable Laboratory of State Grid Corporation of China(Beijing,China).Results show that the proposed system is effective and reliable for the monitoring of galloping shape and characteristic frequency,which can predict the trend of destructive vibration behavior and avoid the occurrence of cable breaking and tower toppling accidents,and these features are essential for the safety operation in smart grids.

Distributed Vibration Sensor With Laser Phase-Noise Immunity by Phase-Extraction φ-OTDR

We have demonstrated a distributed vibration sensor based on phase-sensitive optical time-domain reflectometer (φ-OTDR) system exhibiting immunity to the laser phase noise. Two laser sources with different linewidth and phase noise levels are used in the φ-OTDR system, respectively. Based on the phase noise power spectrum density of both lasers, the laser phase is almost unchanged during an extremely short period of time, hence, the impact of phase noise can be suppressed effectively through phase difference between the Rayleigh scattered light from two adjacent sections of the fiber which define the gauge length. Based on the phase difference method, the external vibration can be located accurately at 41.01 km by the(φ-OTDR system incorporating these two lasers. Meanwhile, the average signal-to-noise ratio (SNR) of the retrieved vibration signal by using Laser I is found to be -37.7 dB, which is comparable to that of -37.5 dB by using Laser II although the linewidth and the phase noise level of the two lasers are distinct. The obtained results indicate that the phase difference method can enhance the performance of(φ-OTDR system with laser phase-noise immunity for distributed vibration sensing, showing potential application in oil-gas pipeline monitoring, perimeter security, and other fields.

Distributed disturbance-observer-based vibration control for a flexible-link manipulator with output constraints

The issue of output constraints is studied for a flexible-link manipulator in the presence of unknown spatially distributed disturbances. The manipulator can be taken as an Euler-Bernoulli beam and its dynamic is expressed by partial differential equations. On account of the uncertainty of disturbances, we present a disturbance observer to estimate infinite dimensional disturbances on the beam. The observer is proven exponentially stable. Considering the problem of output constraints in the practical engineering, we propose a novel distributed vibration controller based on the disturbance observer to fulfill the position regulation of the joint angle and suppress elastic deflections on the flexible link, while confining the regulating errors of output in a suitable scope that we can assign. The closed-loop system is demonstrated exponentially stable based on an integral-barrier Lyapunov function. Simulations validate the effectiveness of the design scheme.

High-resolution photofragment translational spectro- scopy for the UV photodissociation of C_2H_5I

The photodissociation of ethyl iodide at 279.71, 281.73, 304.02 and 304.67 nm has been studied on our new mini-photofragment translational spectrometer with a total flight path of only 5 cm. Some vibra-tional peaks are firstly resolved in the TOF spectra of I*(2P1/2) and I(2P3/2) channels. These vibrational peaks are assigned to the excitation states (ν2 = 0, 1, 2,…) of the umbrella mode (ν2, 540 cm-1) of the photofragment C2H5, and the distribution of the vibrational states is obtained. The dissociation energy has been determined to be D0(C-I)=2.314 ± 0.03 eV. The energy partitioning of the available energy (Eavl=ET+Eint=ET+EV,R) calculated from our experimental data E int /E avl= 22.1% at 281.73 nm, 22.4% at 304.02 nm for the I* channel, and E int /E avl= 25.2% at 279.71 nm, 25.9% at 304.67 nm for the I channel, seem to be more reliable.

Photodissociation of acryloyl chloride in the gas phase

The 193 nm photodissociation dynamics of CH2CHCOC1 in the gas phase has been examined with the technique of time-resolved Fourier transform infrared emission （TR-FTIR） spectroscopy. Vibrationally excited photofragments of CO （v ≤ 5）, HC1 （v ≤ 6）, and C2H2 were observed and two photodissociation channels, the C-C1 fission channel and the HC1 elimina- tion channel have been identified. The vibrational and rotational state distributions of the photofragments CO and HC1 have been acquired by analyzing their fully rotationally resolved v→ v- 1 rovibrational progressions in the emission spectra, from which it has been firmly established that the mechanism involves production of HC1 via the four-center molecular elimination of CH2CHCOC1 after its internal conversion from the S1 state to the So state. In addition to the dominant C--C1 bond fission along the excited S1 state, the S1→S0 internal conversion has also been found to play an important role in the gas phase photolysis of CH2CHCOC1 as manifested by the considerable yield of HC1.