Distributed intelligent management of active networks

This paper focuses on improving computer network management by the adoption of artificial intelligence techniques. A logical inference system has being devised to enable automated isolation, diagnosis, and even repair of network problems, thus enhancing the reliability, performance, and security of networks. We propose a distributed multi-agent architecture for network management, where a logical reasoner acts as an external managing entity capable of directing, coordinating, and stimulating actions in an active management architecture. The active networks technology represents the lower level layer which makes possible the deployment of code which implement teleo-reactive agents, distributed across the whole network. We adopt the Situation Calculus to define a network model and the Reactive Golog language to implement the logical reasoner. An active network management architecture is used by the reasoner to inject and execute operational tasks in the network. The integrated system collects the advantages coming from logical reasoning and network programmability, and provides a powerful system capable of performing high-level management tasks in order to deal with network fault.

The propagation mechanism of a vortex on the β plane

The propagation velocity and propagation mechanism for vortices on a β plane are determined for a reduced-gravity model by integrating the momentum equations over the β plane. Isolated vortices, vortices in a background current, and initial vortex propagation from rest are studied. The propagation mechanism for isolated anticyclones as well as cyclones, which has been lacking up to now, is presented. It is shown that, to first order, the vortex moves to generate a Coriolis force on the mass anomaly of the vortex to compensate for the force on the vortex due to the variation of the Coriolis parameter. Only the mass anomaly of the vortex is of importance, because the Coriolis force due to the motion of the bulk of the layer moving with the vortex is almost fully compensated by the Coriolis force on the motion of the exterior flow. Because the mass anomaly of a cyclone is negative the force and acceleration have opposite sign. The role of dipolar structures in steadily moving vortices is discussed, and it is shown that their overall structure is fixed by the steady westward motion of the mass anomaly. Furthermore, it is shown that reduced-gravity vortices are not advected with a background flow. The reason for this behavior is that the background flow changes the ambient vorticity gradient such that the vortex obtains an extra self-propagation term that exactly cancels the advection by the background flow. Last, it is shown that a vortex initially at rest will accelerate equatorward first, after which a westward motion is generated. This result is independent of the sign of the vortex.

Rotational spectra induced by vibrations

Mizushima and Venkateswarlu showed in 1953 that certain molecules have the property that excited vibrational states may possess rotational spectra even when the rotational spectrum of the ground vibrational state is forbidden by symmetry. We call such a spectrum a vibrationally induced rotational spectrum, and have made a systematic examination of the point groups which permit such behaviour. We also give formulae for the approximate line frequencies and intensities in these spectra, and discuss some of the problems involved in observing them. The spectra can only arise from degenerate vibrational states, and are of three possible types: i) symmetric top perpendicular spectra, shown by molecules belonging to the point groups Dnh, Dn and Cnh, where n is odd; (ii) symmetric top parallel spectra, shown by molecules belonging to Dnd and S2n, where n is even; and (iii) spherical top spectra, shown by molecules belonging to T or Td. Excited vibrational states of polar molecules of point groups Cnv or Cn, where n is odd, may also possess vibrationally induced perpendicular components of type (i), in addition to their ordinary parallel spectra. In addition to the above limitations on the point groups there are, in general, limitations on the symmetry species of the degenerate vibrational states.

The equilibrium structure of HCN

The equilibrium structure of HCN has been determined from the previously published ground state rotational constants of eight isotopomers by using (B0‐Be) values obtained from a variational calculation of the vibration–rotation spectrum. The results are re(CH)=1.065 01(8) Å, and re(CN)=1.153 24(2) Å.

Coriolis perturbations in the infrared spectrum of allene

High resolution infrared spectra of the ν9 and ν10 perpendicular fundamentals of the allene molecule are reported, in which the J structure in the sub-bands has been partially resolved. Analysis of the latter shows that the vibrational origin ν9 = 999 cm−1, some 35 cm−1 below previous assignments. The pronounced asymmetry in the intensity distribution of the rotational structure which this assignment implies is shown to be expected theoretically, due to the Coriolis perturbations involved, and it is interpreted in terms of the sign and magnitude of the ratio of the dipole moment derivatives in the two fundamentals. The results of this analysis are shown to be in good agreement with observations on allene-1.1-d2, where similar intensity perturbations are observed, and with an independent analysis of the ν8 band of allene-h4. The A rotational constant of allene-h4 is found to have the value 4.82 ± 0.01 cm−1, and for the molecular geometry we obtain r(CH) = 1.084 A, r(CC) = 1.308 A, and HCH = 118.4°. A partial analysis of the rotational structure of the hot bands (ν9 + ν11 − ν11) and (ν10 + ν11 − ν11) is presented; these provide an example of a strong Coriolis interaction between nearly degenerate A1A2 and B1B2 pairs of vibrational levels. Some localized rotational perturbations in the ν9 and ν10 fundamentals are also noted, and their possible interpretations are discussed.

Vibration-rotation spectra of CH3F

Rotational structure has been resolved and analyzed in the 1049-cm−1 parallel fundamental and the 1182 cm−1 perpendicular fundamental bands in the infrared spectrum of the CH3F molecule. Combination bands at 2223 cm−1 and around 2650 cm−1 have also been studied. The effective resolving power of the spectrometer was 0.25 cm−1 for all these bands. The two long-wavelength fundamentals have been analyzed in much greater detail than in previous work, and a complete analysis of the perpendicular band has been made, including the J-structure in the P and R branches of the sub-bands. Rotational constants of CH3F determined in this work and elsewhere are summarized in Table XIII of the text. Some anomalous intensity perturbations in the rotation lines of the 1182-cm−1 fundamental have been observed, and are discussed.

The two-dimensional anharmonic oscillator III: the CCC bending mode of C3O2

Newly observed data on the rotational constants of carbon suboxide in excited vibrational states of the low-wavenumber bending vibration ν7 have been successfully interpreted in terms of the two-dimensional anharmonic oscillator wavefunctions associated with this vibration. By combining these results with published infrared and Raman spectra the vibrational assignment has been extended and a refined bending potential for ν7 has been derived: this has a minimum at a bending angle of about 24° at the central C atom, with an energy maximum at the linear configuration some 23 cm−1 above the minimum. From similar data on the combination and hot bands of ν7 with ν4 (1587 cm−1) and ν2 (786 cm−1) the effective ν7 bending potential has also been determined in the one-quantum excited states of ν4 and ν2. The effective ν7 potential shows significant changes from the ground vibrational state; the central hump in the ν7 potential surface is increased to about 50 cm−1 in the v4 = 1 state, and decreased to about 1 cm−1 in the v2 = 1 state. In the light of these results vibrational assignments are suggested for most of the observed bands in the infrared and Raman spectra of C3O2.

Vibration-rotation spectra and the harmonic force field of HOCl

Vibration-rotation spectra of HOCl have been measured at a resolution of 0.05 cm−1 to determine vibration rotation constants, and 35–37 Cl isotope shifts in the vibration frequencies. The spectrum of DOCl has also been recorded, and a preliminary analysis for the band origins has been made. The vibrational frequency data and centrifugal distortion constants have been used to determine the harmonic force field in a least-squares refinement; the force field obtained also gives a good fit to data on the vibrational contributions to the inertial defect. The equilibrium rotational constants of HOCl have been obtained, and an equilibrium structure has been estimated.

Vibration-rotation bands of diazomethane

Some absorption bands of diazomethane vapour between 1950-3500 cm-1 have been measured with very high resolving power. The rotational structure of two parallel bands and of one perpendicular band has been resolved, and approximate values have been determined for the rotational constants. The results are consistent with the geometrical structure usually accepted for this molecule. A peculiarity in the results for the band near 2100 cm-1, together with other facts, leads to the suggestion that a tautomeric form of this molecule exists, HCN=NH, being an isoelectronic analogue of hydrazoic acid.

Coriolis perturbations in the infrared spectrum of diborane

High‐resolution infrared spectra of B2H6 vapor are reported. The sample was prepared from the naturally occurring 11B☒10B isotopic mixture. The rotational structure of the infrared bands has been analysed for Coriolis perturbations due to rotation about the axis of least moment of inertia (the B⋅⋅⋅B axis). The following results have been obtained: (a) interaction between the Type A fundamental ν18 and the inactive fundamental ν5 has been observed, thus confirming the assignment of ν5 at 833 cm—1, giving ∣ ζ5,18Z ∣=0.55±0.05; (b) interaction observed between the Type A combination band (ν10+ν12) at 1283 cm—1 and the inactive combination (ν10+ν7) gives an estimate of the unobserved fundamental ν7 as 850±30 cm—1, and an estimate of ∣ ζ7,12Z ∣=0.6±0.1; (c) the absence of any observed perturbation of the Type C fundamental ν14 at 973 cm—1, suggests, by negative arguments, that either the unobserved fundamental ν9 does not lie in the frequency range 900 to 1100 cm—1, or ∣ ζ9,14Z ∣<0.2. The assignment of the unobserved fundamental vibrations of diborane is discussed in the light of this evidence.

The harmonic force field and rz structure of HNCO

The presently available microwave, millimeter wave, and far-infrared data of five isotopic species of isocyanic acid, namely, HNCO, H15NCO, HN13CO, HNC18O, and DNCO, have been used to obtain improved values of the ground-state rotational constants, the five quartic distortion constants, and some higher-order distortion constants in the Ir S reduced Hamiltonian of Watson. The appropriate planarity relation among the quartic centrifugal distortion constants has been imposed in the fitting procedure. The general harmonic force field of isocyanic acid has been determined using all existing data, and assuming a trans bent equilibrium geometry of the molecule with an NCO angle of 170°. Finally an rz structure has been obtained using the Az, Bz, and Cz rotational constants of five isotopic species. The bending of the NCO chain is found to be 8° in the trans configuration.

Perturbations in the infrared spectrum of monofluoroacetylene, and their relationship to intramolecular vibrational energy redistribution

Several high-order vibration-rotation perturbations in the high-resolution infrared spectrum of monofluoroacetylene, HCCF, are assigned and analyzed in detail. They result in avoided crossings in the rotational structure of several bands, and precise values for the effective high-order terms in the Hamiltonian have been determined. The significance of these results for intramolecular vibrational redistribution is discussed.

Simultaneous observations of reconnection pulses at Cluster and their effects on the cusp aurora seen at Chinese Yellow River Station

While the Cluster spacecraft were located near the high-latitude magnetopause, between 10:10 and 10:40 UT on 16 January 2004, three typical flux transfer event (FTE) signatures were observed. During this interval, simultaneous and conjugated all-sky camera measurements, recorded at Yellow River Station, Svalbard, are available at 630.0 and 557.7nm that show poleward-moving auroral forms (PMAFs), consistent with magnetic reconnection at dayside magnetopause. Simultaneous FTEs seen at the magnetopause mainly move northward, but having duskward (eastward) and tailward velocity components, roughly consistent with the observed direction of motion of the PMAFs in all-sky images. Between the PMAFs meridional keograms, extracted from the all-sky images, show intervals of lower intensity aurora which migrate equatorward just before the PMAFs intensify. This is strong evidence for an equatorward eroding and poleward moving open-closed boundary (OCB) associated with a variable magnetopause reconnection rate under variable IMF conditions. From the durations of the PMAFs we infer that the evolution time of FTEs is 5-11 minutes from its origin on magnetopause to its addition to the polar cap.

Carbon suboxide: the vibrational dependence of the v7 bending potential function

Data on the vibrational energy levels and rotational constants of carbon suboxide for the low-wavenumber bending mode ν7 are reviewed, in the ground-state manifold, and in the ν2-, ν3-, ν4-, and ν2 + ν4-state manifolds. Following the procedure developed by Duckett, Mills, and Robiette [J. Mol. Spectrosc. 63, 249 (1976)] the data have been inverted to give the effective bending potential in ν7 for each of these five states. Values are obtained for various other parameters in the effective vibration-rotation Hamiltonian. The potential and rotational constants in ν2 + ν4 are given to a close approximation by linear extrapolation from the ground state through the ν2 and ν4 states.

The calculation of force constants and normal co-ordinates--VII Normal co-ordinates in the E species of allene

Force constant and normal co-ordinate calculations are reported for the E species vibrations of the allene molecule. Data on the fundamental vibration frequencies of allene-h4, allene-d4 and allene-1.1-d2 and on the five experimentally determined Coriolis zeta constants of C3H4 and C3D4, were used in a force constant refinement procedure. Allowing for product and sum rules this gives 21 independent data which were used to refine to the most general harmonic force field (10 parameters) with one constraint (in the absence of any constraints the refinement was not satisfactory). The results have been used to calculate the complete ζz Coriolis interaction matrix for the allene-1.1-d2 molecule, and hence to calculate the expected rotational structure of the perpendicular bending vibrations of this molecule; the good agreement obtained with the observed spectra is a check on our results.