Large Number Of Transitions Research Articles

On the 12C2H2 near-infrared spectrum: absolute transition frequencies and an improved spectroscopic network at the kHz accuracy level.

Lamb dips of twenty lines in the P, Q, and R branches of the ν1 + ν3 + ν41 vibrational band of 12C2H2, in the spectral window of 7125-7230 cm-1, have been measured using an upgraded comb-calibrated frequency-stabilized cavity ring-down spectrometer, designed for extensive sub-Doppler measurements. Due to the large number of carefully executed Lamb-dip experiments, and to the extrapolation of absolute frequencies to zero pressure in each case, the combined average uncertainty of the measured line-center positions is 15 kHz (5 × 10-7 cm-1) with a 2-σ confidence level. Selection of the twenty lines was based on the theory of spectroscopic networks (SN), ensuring that a large number of transitions, measured previously by precision-spectroscopy investigations, could be connected to the para and ortho principal components of the SN of 12C2H2. The assembled SN contains 331 highly precise transitions, 119 and 121 of which are in the ortho and para principal components, respectively, while the rest remain in floating components. The para- and ortho-12C2H2 energy-level lists, determined during the present study, contain 82 and 80 entries, respectively, with an accuracy similar to that of the lines. Based on the newly assembled lists of para- and ortho-12C2H2 empirical energy levels, a line list, called TenkHz, has been generated. The TenkHz line list contains 282 entries in the spectral range of 5898.97-7258.87 cm-1; thus far, only 149 of them have been measured directly via precision spectroscopy. The TenkHz line list includes 35 intense lines that are missing in the HITRAN2020 database.

Precision spectroscopy of molecular hydrogen ions: an introduction

The molecular hydrogen ions (MHI) are composed of only two nuclei and a single electron. These simplest molecules are fascinating systems at the interface of atomic and molecular physics. Compared to atoms, they present the additional degrees of freedom of vibration and rotation. The spectrum of rovibrational energies provides an exceptionally large number of transitions that are potentially measurable with extremely small fractional uncertainty. After two decades of theoretical and experimental efforts, precision studies of the vibrational transition frequencies have now reached fractional uncertainties in the low- range. This is nearing the level of the most accurate experiment-theory comparisons in physics, performed on the hydrogen atom and on the g-factor of the electron. We describe the motivation for the study of MHI, present some relevant theoretical and experimental issues, indicate a few salient results and give an outlook towards future opportunities.

Development of a resource-saving technology of production of strip-type profiles by drawing in roller dies using dummy passes

The rolling-drawing process is used in the production of a large number of shaped profiles of complex configuration, including thin-walled, strip and periodic section profiles. This process, in comparison with drawing in monolithic dies, allows to reduce energy costs by 20–40 %, to increase deformation in one pass to 40–50 %, to reduce the number of preparatory operations (heat treatment, pickling), to exclude the use of expensive lubricants for drawing. Compared to the production of profiles by the method of cold rolling, the rolling-die process has a higher technological flexibility, does not require significant capital investments when organizing the production of precise profiles. At the same time, due to the presence of tensile stresses at the edges of the profile, which can cause their destruction, the assortment of strip-type profiles produced by this method was previously limited to readymade profiles with a ratio of width to height of no more than two. The authors of this work have previously developed a technology for the production of crimped steel strip with a width-to-height ratio of more than 10 by the rolling-drawing method. However, the developed calibration provides for a large number of transitions, complicates the organization of the production of strip profiles of a wide range of sizes, especially in the production of low-tonnage batches. To decrease the number of transitions, the use of dummy paases was proposed. It was shown that this will make it possible to increase the width-to-height ratio of strip-type profiles to 20, and, accordingly, reduce the production cost. The proposed technology for the production of strip-type profiles by the method of drawing in roller dies using dummy passes will allow to comprehensively solve the problem of providing machine-building and instrument-making enterprises by especially precise profiles of a wide range of sizes.

Ionic Nitriding of Certain Parts Protected on Nonfunctional Surfaces With Special Paints. Electric Energy Consumed

The experimental researches on the promotion of new technologies for the local protection of metallic parts against plasma nitriding, led to two types of special paints for protection in ionic nitriding, paints elaborated on the basis of copper lamellar powder in combination with magnesium oxide and carbon tetrachloride. In the created context, it was considered that the elaborated paints could be used not only for preventing the hardening during ionic nitriding of certain technological surfaces of the parts on which they are applied, but also for coating certain nonfunctional surfaces, their degasification taking such a long time. These nonfunctional areas could be: surfaces resulted from casting, fragments with macroirregularities, surfaces that contain slag, residues, soot, other oxides, impurities, etc. and are the cause for a very large number of transitions of the glow discharges in electric arcs. The use of special protecting paints for the plasma nitriding of the parts that present nonfunctional surfaces leads to a major reduction in the energy consumption. This paper presents the ways of determining the consumed electric energy on the basis of absorbed power in the case of ionic nitriding of certain parts protected on nonfunctional surfaces with special paints.

EXACT SOLUTION OF TASKS OF DYNAMIC MODELING OF PROCESSES IN SYSTEMS OF TRANSPORT LOGISTIC

The dynamic models of processes in transport logistics systems are considered. In the literature, such complex systems as the military transport logistics system or the combat vehicle support system are often modeled as a set of typical system states. These states are interconnected by a large number of transitions of a given intensity, which are carried out with given probabilities. Graphically, this is represented using the so-called graph of states and transitions, and the probabilities of the system being in a particular state are the subject of research in such a graph. The methods available in the literature for studying the dynamic characteristics of state graphs and transitions are analyzed. A description of the changes in probabilities as a function of time is made using systems of differential equations, usually linear. Based on practical requirements, approximate solutions to such systems are usually sought. One of the approximate methods is the decomposition method, in which, instead of a system of coupled equations, a set of independent equations is considered, the solution of which is not difficult. The results of the solution have an accuracy satisfactory from the point of view of practical use. The assumptions based on which the decomposition method can be used are analyzed. It is shown that the accuracy of the obtained results substantially depends on the given initial conditions and should increase over time, when this dependence weakens. A method is proposed for the exact solution of a system of differential equations, free of any assumptions. The use of operational calculus is substantiated, which reduces the solution of a system of linear differential equations to the solution of a system of linear algebraic equations for unknown images of the sought-for Laplace functions. The method is used to describe the process of technical support for the restoration of the transport flow of military logistics. The boundaries of the possibility of applying the results of a simpler approximate solution are established.

Optimal multirate sampling in symbolic models for incrementally stable switched systems

Methods for computing approximately bisimilar symbolic models for incrementally stable switched systems are often based on discretization of time and space, where the value of time and space sampling parameters must be carefully chosen in order to achieve a desired precision. These approaches can result in symbolic models that have a very large number of transitions, especially when the time sampling, and thus the space sampling parameters are small. In this paper, we present an approach to the computation of symbolic models for switched systems with dwell-time constraints using multirate time sampling, where the period of symbolic transitions is a multiple of the control (i.e. switching) period. We show that all the multirate symbolic models, resulting from the proposed construction, are approximately bisimilar to the original incrementally stable switched system with the precision depending on the sampling parameters, and the sampling factor between transition and control periods. The main contribution of the paper is the explicit determination of the optimal sampling factor, which minimizes the number of transitions in the class of proposed symbolic models for a prescribed precision. Interestingly, we prove that this optimal sampling factor is mainly determined by the state space dimension and the number of modes of the switched system. Finally, an illustration of the proposed approach is shown on an example, which shows the benefit of multirate symbolic models in reducing the computational cost of abstraction-based controller synthesis.

Multirate Symbolic Models for Incrementally Stable Switched Systems

Methods for computing approximately bisimilar symbolic models for incrementally stable switched systems are usually based on discretization of time and space, where the value of time and space sampling parameters must be carefully chosen in order to achieve a desired precision. This often results in symbolic models that have a very large number of transitions, especially when the time sampling, and thus the space sampling parameters are small. In this paper, we present an approach to the computation of symbolic models for switched systems using multirate time sampling, where the period of symbolic transitions is a multiple of the control (i.e. switching) period. We show that multirate symbolic models are approximately bisimilar to the original incrementally stable switched system. The main contribution of the paper is the explicit determination of the optimal sampling ratio between transition and control periods, which minimizes the number of transitions in the symbolic model. Interestingly, this optimal sampling ratio is mainly determined by the state space dimension and the number of modes of the switched system. Finally, an illustration of the proposed approach is shown for the boost DC-DC converter, which shows the benefit of multirate symbolic models.

Judd–Ofelt analysis of spectroscopic properties of Sm3+ doped P2O5–SrO glasses

The glass composition P2O5 60%, SrO 40% (mol%) was prepared then doped with Sm3+ with different mol% (3.2, 6.4, 9.6 and 15%). UV–VIS–NIR spectrometer was used to carry out the absorption spectra of the studied glass samples. The most nominal transitions were assigned among a large number of transitions. Then the radiative properties of the Sm3+ ions were calculated using J–O analysis. The results show a large value of Ω2 than the values Ω4 and Ω6. Another parameter such as the oscillator strength, radiative life time, the transition probabilities, the spectroscopic quality and factors branching ratio of several excited states of the Sm3+ ions was calculated. The laser transition level from 6F9/2→6H5/2, the gain cross-section has been predicted. The emission profile of Sm3+ ions in the present glass shows that the peak of the gain coefficient is shifted toward shorter wavelength as the increase of the inversion. The Optical properties introduce this doped Sm3+ glass as a promising candidate for optical applications.

Transition-Selective Pulses in Zero-Field Nuclear Magnetic Resonance.

We use low-amplitude, ultralow frequency pulses to drive nuclear spin transitions in zero and ultralow magnetic fields. In analogy to high-field NMR, a range of sophisticated experiments becomes available as these allow narrow-band excitation. As a first demonstration, pulses with excitation bandwidths 0.5-5 Hz are used for population redistribution, selective excitation, and coherence filtration. These methods are helpful when interpreting zero- and ultralow-field NMR spectra that contain a large number of transitions.

γ-ray spectroscopy of fission fragments produced inPb208(O18,f)

Prompt gamma-ray spectroscopy of fission fragments produced in the heavy-ion induced fusion-fission reaction $^{208}\mathrm{Pb}(^{18}\mathrm{O},f)$ at $E=90$ MeV has been performed. The relative isotopic yields of the fission fragments and the fragment mass distribution have been studied. Structures in the mass distribution have been discussed in the light of earlier results. Relative yields of several odd-$A$ isotopes of Mo, Ru, Pd, and Cd and the odd-$A$ isotones with $N=62$ and 64 have been studied along with the yields of the neighboring even-$Z$, even-$N$ fragments and correlated to nuclear structural effects. The average total neutron multiplicity during fission has been measured to be $5.48\ifmmode\pm\else\textpm\fi{}0.59$. The level schemes of the two neutron-rich nuclei $^{110}\mathrm{Pd}$ and $^{116}\mathrm{Cd}$ have been studied from $\ensuremath{\gamma}$-ray triple coincidence data. A large number of transitions, previously reported only from $\ensuremath{\beta}$-decay studies, have been observed in $^{110}\mathrm{Pd}$ for the first time. The yrast band in $^{116}\mathrm{Cd}$ has been extended up to spin $({16}^{+})$. In addition, a rotational sequence built upon an excited ${5}^{\ensuremath{-}}$ state in $^{116}\mathrm{Cd}$ has been observed up to $({13}^{\ensuremath{-}})$. The level schemes have been discussed in the context of existing results, both experimental and theoretical, in the literature.

Rotational spectrum of 4-methylcyanoallene (CH3CH=C=CH-CN), a chiral molecule of potential astrochemical interest

Context. A successful identification of an interstellar compound requires that its spectrum has first been assigned in the laboratory. New and sensitive radiotelescopes, such as ALMA, will make it possible to detect interstellar molecules in much smaller concentrations than before. Cyanoallene (CH2 =C=CH-CN) has recently been observed in the dense molecular cloud TMC-1 by means of its rotational spectrum. Its methyl congener, 4-methylcyanoallene (CH3 CH=C=CH-CN), may also be present in the interstellar medium (ISM). This chiral compound exists in two forms, which are mirror images. Chirality is an essential feature of life. So far, no chiral compounds have been detected in the ISM.Aims. The synthesis and assignment of the rotational spectrum of CH3 CH=C=CH-CN, will facilitate the potential detection of this compound in the ISM. Methods. The spectrum of 4-methylcyanoallene has been recorded between 13 and 116 GHz using the microwave spectrometer at the University of Oslo. The spectroscopic study has been augmented with high-level quantum chemical calculations at the B3LYP/cc-pVTZ and CCSD/cc-pVTZ levels of theory.Results. The rotational spectra of CH3 CH=C=CH-CN in the ground vibrational state and in the first vibrationally excited state are reported for the first time and accurate spectroscopic constants have been obtained from a large number of transitions.

An Analysis of the Effects of Customers’ Migratory Behavior in the Inner Areas of the Sales Floor in a Retail Store on their Purchase

Recently, the analysis of in-store customer behavior has been garnering increasing attention as a marketing strategy of retail stores. In this paper, we focus on the effects of customers’ migratory behavior in the inner areas on the resulting purchase amount. We examine the difference between the shopping path of high-volume customers and that of low-volume customers in the inner side of the sales floor to investigate how purchase amount differs when the shopping path contains a longer migration in the inner areas or a larger number of transitions from the outer areas to the inner areas.

Logic for Mode Transition of Autopilots in Lateral Direction for Commercial Aircrafts

Complexity in autopilot logic design and confusion involved in its mode transition is one of the major reasons for the accidents in highly automated airliner. In this paper we present the usage of a recently proposed array logic based technique for designing the autopilot mode transition logic for a commercial aircraft in the lateral direction. This designing technique helps to reduce the design effort in the development of an autopilot. Ease to understand and very concise way to specify a large number of transitions in simple tabular column is one the highlight of this method. This paper provides some observations about lateral modes and logic concerning lateral mode transition in a less complex way compared to the prevailing methods for autopilot design. Here various mode possibilities of lateral mode transition in an autopilot is mentioned along with specification criteria’s that bound these transition and these possible transitions were given a frame work using MATLAB software

Pure rotational Coherent anti‐Stokes Raman spectroscopy of water vapor and its relevance for combustion diagnostics

In this work, we report for the first time the rotational coherent anti‐Stokes Raman spectroscopy (CARS) spectrum of water vapor, recorded through experiments at 400 K and 670 K for Raman shifts up to 600 cm−1. Using the standard dual‐broadband pure rotational CARS approach, the resonant structure was overwhelmed by a strong non‐resonant background. By employing a polarization technique, this background could be suppressed and the resonant structure discerned. The spectral line structure matched spectra from spontaneous rotational Raman scattering found in the literature. The CARS signal intensity at the highest peak from water vapor at 400 K was more than five orders of magnitude weaker than for N2 because of a low Raman cross section and a larger number of transitions. Due to the weak resonant signal, water vapor is an unsuitable candidate for CARS thermometry and relative concentration measurements in combustion. Still, rotational CARS spectra from product gases in combustion will be affected by the presence of water, which is briefly discussed. Copyright © 2013 John Wiley & Sons, Ltd.

Synthesis, Microwave Spectrum, and Conformational Properties of 2-Fluoroethyl Azide (FCH2CH2N3)

A novel synthesis producing neat 2-fluoroethyl azide (FCH2CH2N3) is described. A conformational analysis using microwave spectroscopy augmented by quantum chemical calculations at the CCSD(T)/cc-pVTZ, B3LYP/aug-cc-pVTZ, and B3LYP/cc-pVTZ levels of theory has been performed for this compound. The spectra of the ground vibrational state and two vibrationally excited states of one rotameric form were assigned. A large number of transitions was assigned, and very accurate values were obtained for the rotational and quartic centrifugal distortion constants. The identified conformer has synclinal orientations for the F-C-C-N and C-C-N-N chains of atoms bringing the fluorine atom and the azido group into close proximity. It is concluded from consideration of absolute intensities that this conformer is indeed the preferred form of the molecule in accord with the theoretical calculations. The experimental and CCSD(T) rotational constants are in very good agreement, whereas much larger discrepancies were seen for the experimental and B3LYP quartic centrifugal distortion constants.

Microwave Spectrum of 2-Aminooxazole, a Compound of Potential Prebiotic and Astrochemical Interest

The microwave spectrum in the 26.6-80 GHz spectral range of 2-aminooxazole, which may have played a potential role in the prebiotic generation of pyrimidine ribonucleotides, is reported. A large number of transitions have been assigned, and accurate values of the rotational and quartic centrifugal distortion constants have been obtained for the four lowest vibrational states. The frequencies of the vibrationally excited states have been determined by relative intensity measurements. The microwave spectra should be useful for the identification of this compound in planetary atmospheres or in interstellar space. 2-Aminooxazole is nonplanar with the amino group bent 35(5) degrees out of the oxazole plane. Inversion of the amino group manifests itself in a characteristic doubling of the microwave transitions and the absence of c-type transitions. The microwave work has been augmented by quantum chemical calculations at the MP2/aug-cc-pVTZ and B3LYP/6-311++G(3df,3pd) levels of theory. The spectroscopic constants obtained by these two methods are in good agreement with one another, as well as with their experimental counterparts. The B3LYP method predicts a more accurate value for the angle between the oxazole ring and the plane formed by the amino group than the MP2 procedure.

A transient low-frequency quasi-periodic oscillation from the black hole binary GRS 1915+105

We present the results of the timing analysis of five Rossi X-ray Timing Explorer observations of the black hole candidate GRS 1915+105 between 1996 September and 1997 December. The aim was to investigate the possible presence of a type B quasi-periodic oscillation (QPO). Since in other systems this QPO is found to appear during spectral transitions from hard to soft states, we analysed observations characterized by a fast and strong variability, in order to have a large number of transitions. In GRS 1915+105, transitions occur on very short time-scales (~s): to single them out we averaged power density spectra following the regular path covered by the source on a 3D hardness-hardness-intensity diagram. We identified both the type C and the type B QPOs: this is the first detection of a type B QPO in GRS 1915+105. As the spectral transitions have been associated to the emission and collimation of relativistic radio-jets, their presence in the prototypical Galactic jet source strengthens this connection.

LFSR-Reseeding Scheme Achieving Low-Power Dissipation During Test

This paper presents a new low-power test-data-compression scheme based on linear feedback shift register (LFSR) reseeding. A drawback of compression schemes based on LFSR reseeding is that the unspecified bits are filled with random values, which results in a large number of transitions during scan-in, thereby causing high-power dissipation. A new encoding scheme that can be used in conjunction with any LFSR-reseeding scheme to significantly reduce test power and even further reduce test storage is presented. The proposed encoding scheme acts as the second stage of compression after LFSR reseeding. It accomplishes two goals. First, it reduces the number of transitions in the scan chains (by filling the unspecified bits in a different manner). Second, it reduces the number of specified bits that need to be generated via LFSR reseeding. Experimental results indicate that the proposed method significantly reduces test power and in most cases provides greater test-data compression than LFSR reseeding alone

A 3000K laboratory emission spectrum of water

An emission spectrum of hot water with a temperature of about 3000 K is obtained using an oxy-acetylene torch. This spectrum contains a very large number of transitions. The spectrum, along with previous cooler laboratory emission spectra and an absorption spectrum recorded from a sunspot, is analyzed in the 500-2000 cm(-1) region. Use of a calculated variational linelist for water allows significant progress to be made on assigning transitions involving highly excited vibrational and rotational states. In particular emission from rotationally excited states up to J=42 and vibrational levels with up to eight quanta of bending motion are assigned.

Spectroscopic and electronic structure studies of protocatechuate 3,4-dioxygenase: nature of tyrosinate-Fe(III) bonds and their contribution to reactivity.

The geometric and electronic structure of the high-spin ferric active site of protocatechuate 3,4-dioxygenase (3,4-PCD) has been examined by absorption (Abs), circular dichroism (CD), magnetic CD (MCD), and variable-temperature-variable-field (VTVH) MCD spectroscopies. Density functional (DFT) and INDO/S-CI molecular orbital calculations provide complementary insight into the electronic structure of 3,4-PCD and allow an experimentally calibrated bonding scheme to be developed. Abs, CD, and MCD indicate that there are at least seven transitions below 35 000 cm(-1) which arise from tyrosinate ligand-to-metal-charge transfer (LMCT) transitions. VTVH MCD spectroscopy gives the polarizations of these LMCT bands in the principal axis system of the D-tensor, which is oriented relative to the molecular structure from the INDO/S-CI calculations. Three transitions are associated with the equatorial tyrosinate and four with the axial tyrosinate. This large number of transitions per tyrosinate is due to the pi and importantly the sigma overlap of the two tyrosinate valence orbitals with the metal d orbitals and is governed by the Fe-O-C angle and the Fe-O-C-C dihedral angles. The previously reported crystal structure indicates that the Fe-O-C angles are 133 degrees and 148 degrees for the equatorial and axial tyrosinate, respectively. Each tyrosinate has transitions at different energies with different intensities, which correlate with differences in geometry that reflect pseudo-sigma bonding to the Fe(III) and relate to reactivity. These factors reflect the metal-ligand bond strength and indicate that the axial tyrosinate-Fe(III) bond is weaker than the equatorial tyrosinate-Fe(III) bond. Furthermore, it is found that the differences in geometry, and hence electronic structure, are imposed by the protein. The consequences to catalysis are significant because the axial tyrosinate has been shown to dissociate upon substrate binding and the equatorial tyrosinate in the enzyme-substrate complex is thought to influence asymmetric binding of the chelated substrate moiety via a strong trans influence which activates the substrate for reaction with O2.