Harmonic Constant Research Articles

Theoretical studies of anharmonic effect on the main reactions involving in NO2 in fuel burning

Using the transition state (TS) theory, the anharmonic and harmonic rate constant are calculated by means of Yao and Lin method for the main reactions related to nitrogen dioxide (NO2) in fuel combustion processes, respectively. A junction occurs between the anharmonic and harmonic rate constant for some bimolecular reactions, and the anharmonic rate constant is higher than the harmonic rate constant at low temperature, normally. The anharmonic effect of those reactions is significant and can’t be neglected at high temperature. Moreover, the modification of the existing reaction mechanisms referring to NO2 in fuel combustion processes is achieved through rate constant.

On the asymptotically Poincaré-Einstein 4-manifolds with harmonic curvature

Abstract In this paper, we discuss the mass aspect tensor and the rigidity of an asymptotically Poincare-Einstein (APE) 4-manifold with harmonic curvature. We prove that the trace-free part of the mass aspect tensor of an APE 4-manifold with harmonic curvature and normalized Einstein conformal infinity is zero. As to the rigidity, we first show that a complete noncompact Riemannian 4-manifold with harmonic curvature and positive Yamabe constant as well as a L 2 -pinching condition is Einstein. As an application, we then obtain that an APE 4-manifold with harmonic curvature and positive Yamabe constant is isometric to the hyperbolic space provided that the L 2 -norm of the traceless Ricci tensor or the Weyl tensor is small enough and the conformal infinity is a standard round 3-sphere.

Propagation characteristics of power line harmonic radiation into the stratified anisotropic ionosphere

Power line harmonic radiation (PLHR), which specifically refers to the electromagnetic wave radiation observed in ionosphere or magnetosphere, is radiated by the transmission lines of power systems on the ground. PLHR is shown as a parallel spectrogram between 400 Hz and 5 kHz in frequency-time power spectrogram of electromagnetic field. And the frequency spacing of the parallel spectrogram is 50/100 Hz or 60/120 Hz. As an artificial pollution source in the near earth space, PLHR has attracted more and more attention. However, so far, there have been little proposed quantitative researches on the formation mechanism. This paper studies the propagation model for the electromagnetic waves generated by the electric dipole source above the non-ideal conductive ground in the stratified anisotropic ionosphere. Based on the method by Lehtinen(2008), a new full-wave finite element method is give to solve the problem. By recursively calculating reflection coefficients and mode amplitudes, the method contains no index increasing items. So it can effectively overcome the numerical overflow in programming calculations. In order to verify the correctness of the method, comparison are made between the existing analytical solutions and the solutions obtained from the proposed method, and they are in excellent agreement. Further more, using the present model, the new method and the associated parameters about practical power lines, ground and ionosphere, we have studied the effects of the frequency of dipole source, the bottom boundary height of ionosphere, the earth conductivity, and the geomagnetic field direction on PLHR propagation in the ionosphere. Results show that when the frequency of radiation source equals the cut off frequency of earth-ionosphere waveguide-guided wave modes, the strength of PLHR for penetrating into the ionosphere becomes larger. Keeping the harmonic current constant, a smaller ground conductivity would be accompanied by a larger power of PLHR. PLHR propagates along the direction of the geomagnetic field in the ionosphere. Therefore, it is much easier for a high-order harmonic radiation of transmission lines to penetrate into the ionosphere along the direction of the geomagnetic field in the areas with low ground conductivity under a certain condition. Results obtained in this paper may have important implications to explain the formation mechanism of PLHR.

Modelling and simulation of trans quasi Z-source inverter as an automatic three phase power conditioner

In this paper, the trans-quasi Z-source inverter (trans QZSI) is modelled using state space averaging technique and small signal analysis. This leads to design of controller for a closed loop system that suitably controls a variable voltage variable frequency three phase supply employing a trans QZSI. The trans QZSI with improved buck-boost capability inherits all the advantages of the traditional ZSI and replaces the conventional PWM inverter in the system. The closed loop controller carefully monitors the input variable voltage and controls the shoot-through duty ratio of the inverter employing third harmonic injection maximum constant boost control method. The whole system is modelled, designed and verified through simulation and laboratory experiment. The proposed closed loop system provides the regulated three phase output perfect as a power conditioner by making an appropriate choice of boost factor and effective dynamic and steady state control.

Rovibrational energy and spectroscopic constant calculations of CH4⋯CH4, CH4⋯H2O, CH4⋯CHF3, and H2O⋯CHF3 dimers.

In this work, we performed a thorough investigation of potential energy curves, rovibrational spectra, and spectroscopic constants for dimers whose interactions are mediated by hydrogen bonds and other hydrogen interactions. Particularly, we deal with CH4⋯CH4, CH4⋯H2O, CH4⋯CHF3, and H2O⋯CHF 3 dimers by employing accurate electronic energy calculations with two different basis sets at the MP2 level of theory. Following this, the discrete variable representation method was applied to solve the nuclear Schrödinger equation, thus obtaining spectroscopic constants and rovibrational spectra. The harmonic constant, ω e , presents a direct relation to the strength of dimer interactions. As a general rule, it was found that a decrease of interatomic distances is followed by the increase of D e for all dimers. This behavior suggests that the interaction of CH4⋯CH4 is the weakest among all dimers, followed by CH4⋯CHF3, CH4⋯H2O and the strongest interaction given by the H2O⋯CHF 3 dimer.

Performance Analysis of Different Control Methods of Z-source Inverter Feeding Induction Furnace Load

Ever increasing demand for electric energy along with the growing environmental concerns and limited fossil fuel resources, the renewable energy sources are gaining increasing impetus across the globe. The output voltage of these renewable energy sources has a variation range. In these situations an additional DC-DC boost converter or step-up transformer is usually needed. The Z-source inverter (ZSI) is an emerging topology for power electronics converters with very interesting properties such as buck boost characteristics and single stage conversion. In this work, the performance of four control techniques of Z-source inverter - simple boost control, maximum boost control, maximum constant boost control & third harmonic injected maximum constant boost control with induction furnace load, are compared. The simulation results based on MATLAB/Simulink are presented to illustrate the performance comparison of control techniques of ZSI for reducing the harmonic distortion in the load current with induction furnace load in the distribution network.

Elimination of two‐photon excited fluorescence using a single‐beam coherent anti‐Stokes Raman scattering setup

In this report, we demonstrate how to obtain Raman spectra from single‐beam CARS measurements under the condition of strong overlapping two‐photon excited fluorescence (2PEF). Our approach is based on the use of a narrowband phase gate implemented via femtosecond laser pulse shaping from a single broadband laser source, without any use of polarization or amplitude modulation. The decisive quantity regarding the creation of 2PEF with shaped laser pulses is the second harmonic power spectrum, which shows a different dependence on the excitation phase from the CARS signal generation. By shifting the phase or the position of the gate in an appropriate way, it is possible to keep the second harmonic power spectrum and 2PEF constant, paving the way for an elimination of it. This allows to reconstruct the Raman signal and to retrieve quantitative information of resonances even when the fluorescence is about 160 times larger than the CARS signal. Copyright © 2013 John Wiley & Sons, Ltd.

Some Classes of Pseudosymmetric Contact Metric 3-Manifolds

We study (a) the class of 3-dimensional pseudosymmetric contact metric manifolds with harmonic curvature and constant along the direction of and (b) the class of ()-contact metric pseudosymmetric 3-manifolds of type constant in the direction of .

Complete noncompact manifolds with harmonic curvature

Let (Mn, g) be an n-dimensional complete noncompact Riemannian manifold with harmonic curvature and positive Sobolev constant. In this paper, by employing an elliptic estimation method, we show that (Mn, g) is a space form if it has sufficiently small Ln/2-norms of trace-free curvature tensor and nonnegative scalar curvature. Moreover, we get a gap theorem for (Mn, g) with positive scalar curvature.

Green’s function approach for calibrating tides in a circulation model for the East Asian marginal seas

A simple effective method of inverse estimation provided by model Green’s functions is examined to calibrate tides in a regional circulation model for the East Asian marginal seas. The Green’s function optimization derived by perturbing the model parameters significantly improves the estimate relative to observation as compared with baseline integration. Among the optimized model parameters, the largest effects on cost function reduction come first from the harmonic constant of M2 along the open boundaries with the optimized values of 89.7 ± 0.8% for amplitude, and second from the bottom friction with the optimized value of (3.06 ± 0.08) × 10−3.

Numerical Simulation of Barotropic Tides around Taiwan

A 1/12°, 2-D barotropic tide model was used to examine the characteristics of barotropic tides and to improve the accuracy of predicting tidal sea levels and currents in the seas around Taiwan. The form ratio suggests that tides are predominantly semidiurnal in the northern reaches of the Taiwan Strait and mixed of diurnal and semidiurnal elsewhere around Taiwan. When the dominant M2 wave enters the Strait from the north, its amplitude is magnified to ~2 m in the middle, and then decreases rapidly toward the south end of the Strait. The predominance of diurnal tides along the southwest to the south coast of Taiwan is attributed to the quasi-resonance of diurnal waves in the South China Sea. The tidal range is small and tidal currents are weak off the east coast of Taiwan. Barotropic tidal energy is mostly dissipated on the shallow banks of the southwestern Strait. Results summarized from sensitivity tests on the bottom drag coefficient (CD) and horizontal eddy viscosity (AM) indicate that CD = 0.0015 - 0.00175 and AM = 150 m 2 s -1 lead to the best model-data fit when compared to the observed tidal sea levels at ten reference tide-gauge stations around Taiwan. The averaged root-mean-squared (RMS) differences of the simulated tidal sea level for the six principal constituents of O1, P1, K1, N2, M2, and S2 are significantly reduced to 1.3, 0.7, 2.0, 1.6, 5.1, and 3.1 cm, respectively, compared to that calculated from a 0.5° resolution global tide harmonic constant database, NAO.99b (Matsumoto et al. 2000). The averaged RMS differences of barotropic tidal currents (U, V) for O1, K1, M2, and S2 are (0.92, 1.64), (1.17, 0.61), (3.88, 2.37), and (1.52, 1.20) cm s -1 . A database of tidal sea levels and current harmonic constants,

금강하구둑 축조 전·후의 지형변화에 관한 연구

금강하구둑 축조 전 <TEX>${\cdot}$</TEX> 후의 조석변화를 알기위하여 금강하구의 조류조화상수 및 비조화상수를 분석하였다. 그 결과, 하구둑 축조 후에 조화상수 및 비조화상수가 증가하였다. 또한 연도별 해도자료를 이용하여 구간별 수심변화를 분석하였다. 그 결과 남 <TEX>${\cdot}$</TEX> 북측도류제 사이의 수로에서는 세굴이 발생하였다. 그리고 군산외항에서 하구둑까지의 수로에서는 퇴적이 발생하였다. 조석변화는 건설과 준설, 금강하구둑의 수문닫힘의 영향으로 판단된다 그리고 수심변화는 금강하구둑 건설과 남측도류제, 군장 국가공단 조성사업, 새만금 4호 방조제 건설의 영향에 의하여 야기된 것으로 판단된다. We analyzed the harmonic and non-harmonic constant of Geum River estuary to know tidal change of the before and after construction at Geum River estuary dike. As a result of analysis, the harmonic and non-harmonic constant after estuary dike building increased. Also, depth change analyzed at each section by using each year chart data. As a result, scour was occurred in the channel between south and north side guide bank. And accretion was occurred at channel from Kunsan outer port to estuary dike. Tidal change was judged as the effect of construction and dredge, watergate closing at Geum River estuary dike. And water depth change is a cause by effection of Geum River estuary dike construction and, south-north side guide bank, Kunjang country industrial complex furtherance business, seamangeum 4th sea bankment construction.

Numerical simulation of the Adriatic Sea principal tidal constituents

Abstract. The primary goal of this study was to incorporate data-derived harmonic constants into a complex dynamic model using a form of variational data assimilation, with a view to improve the prediction of 7 dominant tidal constituents in the Adriatic Sea. Firstly, harmonic-constant data for 6 Adriatic stations were fed into a steady-state, 3-D, forward/inverse model to furnish optimal boundary conditions (OBCs). Calculated OBCs were then used to derive individual constituent responses, as well as to synthesise seven-constituent boundary conditions for the time stepping, 3-D model. A separate set of 25 stations provided control harmonic constant data. In validating the model output particular attention has been given to the often-ignored tidal currents. To that end 14 current meter data records were processed into tidal current ellipse parameters and used to examine the comparable model output. Comparison to gauge data has shown that the present solution is better than our own previous one, and shows an improvement over recent solutions by other authors. The model accurately reproduces available data with individual station amplitude differences rarely exceeding 1cm, and with the phase error commonly staying well below 10°. For all tidal constituents individual station differences result in RMSE in the 0.33-0.71-cm range for amplitude, and the 5.6°-19.2° range for phase. Semidiurnal currents appear to be modelled better than the diurnal ones (generally over-predicted). High eccentricity of both data and model-derived ellipses often impaired calculating the proper sense of rotation; inclination of the ellipses proved to be the most robust parameter, successfully predicted for most constituents at all depths.

Non-Born–Oppenheimer treatment of the H2 Hookean molecule

We show that the exact non-Born-Oppenheimer Schrodinger equation for the Hookean diatomic molecule H2 (a two-proton, two-electron system where the electron-proton interaction is harmonic while the proton-proton and electron-electron interactions are Coulombic) can be decoupled into equations describing the relative motion of the electrons, the relative motion of nuclei, the motion of a collective mode representing a three-dimensional harmonic oscillator, and the motion of a free particle expressed as a linear combination of the individual center-of-mass coordinates of the nuclei and electrons. Analytic solutions to the relative motion of electrons can be readily obtained for the given values of the harmonic coupling constant. However, exact analytic solutions to the equation for the relative motion of the nuclei cannot be obtained simultaneously due to the fact that the harmonic constants in these two equations are coupled. For this reason, we present for the relative nuclear motion approximate analytic wave functions, one of them obtained variationally and the other by a series solution where the coefficients are determined recursively. We also explore a variational solution to the Taylor-series expansion of the nuclear interaction potential. Properties of the electronic and nuclear intracule densities are examined at different values of the coupling constant. An interesting result of the present non-Born-Oppenheimer treatment of this harmonic model is the fact that the relative nuclear motion occurs in a highly correlated regime. This leads in a natural way to a spatial localization of the nuclei akin to Wigner electronic crystallization.

Optical and Acoustical Frequencies in a Nonlinear HelicoidalModel of DNA Molecules

We compare optical and acoustical frequencies in thePeyrard–Bishop–Dauxois model, i.e. an extended Peyrard–Bishopmodel, of DNA molecules. We discuss how ratio of those frequenciesdepends on a value of the harmonic constant of the helicoidal spring K.Also, we suggest that the most favourable mode could be a resonance mode.

Three dimensional simulation of tide and tidal current characteristics in the East China Sea

With the fine horizontal (5ˈ × 5ˈ) and vertical (15 levels) grids, a three-dimensional model, imbedded a closure turbulence sub-model, was used to calculate the barotropic tides and tidal currents in the Bohai Sea, Yellow Sea, and East China Sea. The computational results are in good agreement with the observed M2, S2, K1 and O1 tides in the domain. Comparison with fifty tide gauges showed that the averaged absolute differences between the simulated and observed amplitudes are only 3.95, 2.96, 2.5 and 1.78 cm for the M2, S2, K1 and O1 tidal waves, respectively. The averaged phase-lag differences of the four tides are 6.88, 6.96, 5.96 and 6.16°. The model reproduces well the tidal charts and this characteristic is discussed in detail. Comparison with 13 current stations, gave averaged absolute deviations between the calculated and observed harmonic constant of the eastern and northern tidal current of 〚6.53, 20.4, 7.55, 24.9〛; 〚3.24, 24.2, 2.89, 22.8〛; 〚2.98, 22.4, 3.6, 25.9〛; 〚2.39, 35.8, 2.01 cm s –1, 22.6°〛 for M2, S2, K1 and O1, respectively. The calculated structures of the tidal current ellipse in the vertical are in fair agreement with the observations. The surface distributions of the tidal current ellipse in the four tidal systems and the maximum current distributions are discussed in detail.

Simulation of the dynamics of electron transfer reactions in polar solvents: Semiclassical trajectories and dispersed polaron approaches

Simulation methods for exploring the microscopic aspects of electron transfer (ET) reactions are developed. For the high temperature limit, where anharmonicity effects are crucial, we develop a semiclassical trajectory (ST) method. This method treats the reaction by considering the time dependence of the electronic energy gap along the classical trajectories of the solvent molecules. The ST approach, which appears as an ad hoc approach, might be at present the most rigorous practical models for simulating ET reactions. That is, this method reproduces the results of the quantum mechanical harmonic test case in the high temperature statistical limit. More importantly, for anharmonic systems it provides a rate constant which depends on the proper activation free energy; this dependence cannot be evaluated by any of the current quantum mechanical methods. For the low temperature range we develop a ‘‘dispersed polaron’’ model that uses the Fourier transform of the microscopic energy gap to evaluate the harmonic Franck–Condon factors of the system. These Franck–Condon factors are then used to evaluate the quantum mechanical harmonic rate constant. The potential of our approach is outlined by considering its implementation in studies of several key problems. This includes: (i) Studies of the effect of solvent dynamics and the role of dielectric relaxation times. (ii) Studies of the actual microscopic activation free energy. (iii) Exploration of the role of vibronic channels in the inverted region. (iv) Transition between the adiabatic and diabatic limits.

Dielectric, pyroelectric, and thermal properties of LiNH4SO4 and LiND4SO4

Measurements of optical second harmonic generation, specific heat, dielectric constant, and pyroelectric coefficient of LiNH4SO4 and its deuterated analog are reported over a temperature range which includes the two phase transitions near 283 K and 459 K. The results indicate that these materials are potentially useful as pyroelectric detectors. Pyroelectric and second harmonic generation data show that the phase below ∼ 283 K is polar.

Isotope chemistry and molecular structure. Deviations from the first rule of the mean

The method of the finite orthogonal polynomial expansions of the Bigeleisen–Mayer function is used to study deviations from the first rule of the mean of isotope chemistry. It is shown by sample calculations for hydrogen isotope substitution in water, methane, and ethylene and carbon isotope substitution in ethylene that the second order corrections, (h//kT)4Σδλ2i account for all but ±0.001 to ±0.01 of the natural logarithm of the symmetry corrected exact harmonic disproportionation constant at 300 °K. The structure of the second order corrections have been related to the molecular structure through the use of internal coordinates. It is shown that subrules local to sets of equivalent coordinates exist in addition to the sum rules formed over the common symmetry classes or the totality of molecular eigenvalues. The local subrules are conveniently expressed in matrix form, D matrix. The latter can be used as a basis for the derivation of the sum rules. The first and second order D matrices are derived for isotopic disproportionation reactions involving both end atom and central atom isotopic substitutions. For end atom isotopic substitution, stretching coordinates cannot lead to deviations from the rule of the mean without kinetic or potential energy coupling from other coordinates, i.e., the local sum rule for pure stretching coordinates holds to all orders. It is shown that the second order deviations from the rules of the mean depend only on the square of differences in isotopic reciprocal masses and only those force constants relating to atoms for which there is isotopic substitution. Detailed analyses of the deviations from the rules of the mean are given for the disproportionation reactions studied, in terms of the molecular geometries, forces, and masses.

Structural phase transition of a linear magnetic chain under the influence of external magnetic field and stress

A “sui generis” structural phase transition is theoretically obtained, as a function of external magnetic field and stress, for a linear chain with (harmonic and unharmonic) crystalline and (XY with space dependent coupling coefficient) ferromagnetic first-neighbour interactions. In the presence of an external magnetic field perpendicular to the XY plane, and at a fixed chain length, we find that: (a) the wave vector of the mode which “freezes” at the transition depends on the magnetic field, the exchange integral and the elastic harmonic constant; all values are allowed for this wave vector and it changes continuously with temperature in the interior of the ordered phase; (b) transitions are of the second order, and the structural order may increase with increasing temperature; (c) unharmonic terms favour configurations with a great number of atoms per unit cell. In the presence of uniaxial external stress and for vanishing magnetic field, we find that: (d) the critical temperature decreases (increases) ...