Accurate Determination of the Values of Fundamental Physical Constants: The Basis of the New “Quantum” SI Units

The metric system appeared as the system of units designed for macroscopic (laboratory scale) measurements. The progress in accurate determination of the values of quantum constants (such as the Planck constant) in SI units shows that the capabilities in high-precision measurement of microscopic and macroscopic quantities in terms of the same units have increased substantially recently. At the same time, relative microscopic measurements (for example, the comparison of atomic transition frequencies or atomic masses) are often much more accurate than relative measurements of macroscopic quantities. This is the basis for the strategy to define units in microscopic phenomena and then use them on the laboratory scale, which plays a crucial role in practical methodological applications determined by everyday life and technologies.The international CODATA task group on fundamental constants regularly performs an overall analysis of the precision world data (the so-called Adjustment of the Fundamental Constants) and publishes their recommended values. The most recent evaluation was based on the data published by the end of 2014; here, we review the corresponding data and results. The accuracy in determination of the Boltzmann constant has increased, the consistency of the data on determination of the Planck constant has improved; it is these two dimensional constants that will be used in near future as the basis for the new definition of the kelvin and kilogram, respectively. The contradictions in determination of the Rydberg constant and the proton charge radius remain. The accuracy of determination of the fine structure constant and relative atomic weight of the electron has improved.Overall, we give a detailed review of the state of the art in precision determination of the values of fundamental constants. The mathematical procedure of the Adjustment, the new data and results are considered in detail. The limitations due to macroscopic properties of material standards (such as the International prototype of the kilogram) and the isotopic composition of substances involved in precision studies in general (as standard measures for the triple point of water) and, in particular, in the determination of the fundamental constants are discussed. The perspectives of the introduction of the new quantum units, which will be free from the mentioned problems, are considered.Many physicists feel no sympathy for the International system of units (SI), believing that it does not properly reflect the character of physical laws. In fact, there are three parallel systems, namely the systems of quantities, system of their units and the related standards. The definition of the units, in particular, the SI units, above all, reflects our ability to perform precision measurements of physical values under certain conditions, in particular, to create appropriate standards. This requirement is not related to the beauty of fundamental laws of nature. More accurate determination of the fundamental constants is one of the areas where we accumulate such experience.     

Recent understanding on the subgrid-scale modeling of large-eddy simulation in physical space

In the last 50 years, the methodology of large-eddy simulation (LES) has been greatly developed, while lots of different subgridscale (SGS) models have appeared. However, the understanding of the procedure of SGS modeling is still not clear. The present contribution aims at reviewing the recent SGS models and, more importantly, expressing our recent understanding on the SGS modeling of LES in physical space. Taking the Kolmogorov equation for filtered quantities (KEF) as an example, it is argued that the KEF alone is not enough to be a closure method. Three physical laws are then introduced to complete this closure procedure and are expected to inspire the future researches of SGS modeling.     

Fundamental metrology in the future: Measuring the single quantum

Great progress has been made over the past 50 years in replacing artefact definitions of the SI base units by those based on fundamental constants. However it is important to recognise that the development of the SI is not ‘complete’ once the base units are all defined in this way. New physics and technologies can always be expected to emerge and these will require developments and modifications to the SI. At the present time a dominant trend seems to be that measurements are changing from dealing with average properties of ensembles to metrology on single entities. This is already apparent for single atoms, ions or photon detection and measurement but can be expected to extend into the technologically important areas of single spins, single THz photons and even phonons in the future. Another significant development may be expected towards measurement of quite different physical quantities from those currently required, such as spin current, decoherence time etc. The paper addresses some of these issues, as well as the influence of quantum mechanics on precise measurement, which will also increase as metrology addresses both single entities and the nano scale.     

On the tuning of variable piezoelectric transducer circuitry network for structural damage identification

The concept of using piezoelectric transducer circuitry with tunable inductance has been recently proposed to enhance the performance of frequency-shift-based damage identification method. While this approach has shown promising potential, a piezoelectric circuitry tuning methodology that can yield the optimal damage identification performance has not been synthesized. This research aims at advancing the state-of-the-art by exploring the characteristics of inductance tuning such that the enrichment of frequency measurements can be effectively realized to highlight the damage occurrence. Analysis shows that when the inductance is tuned to accomplish eigenvalue curve veering, the change of system eigenvalues induced by structural damage will vary significantly with respect to the change of inductance. Therefore, by tuning the inductance near the curve-veering range, one may obtain a family of frequency response functions that could effectively reflect the damage occurrence. When multiple tunable piezoelectric transducer circuitries are integrated to the mechanical structure, multiple eigenvalue curve veering can be simultaneously accomplished, and a series of inductance tunings can be formed by accomplishing curve veering between different pairs of system eigenvalues. It will then be shown that, to best characterize the damage occurrence, the favorable inductance tuning sequence should be selected as that leads to a “comprehensive” set of eigenvalue curve veering, i.e., all measurable natural frequencies undergo curve veering at least once. An iterative second-order perturbation-based algorithm is used to identify the locations and severities of the structural damages based on the frequency measurements before and after the damage occurrence. Numerical analyses on benchmark beam and plate structures have been carried out to examine the system performance. The effects of measurement noise on the effectiveness of the proposed damage identification method are also evaluated. It is demonstrated that the damage identification results can be significantly improved by using the variable piezoelectric transducer circuitry network with the favorable inductance-tuning scheme proposed in this research.     

Acoustic model for robustness analysis of optimal multipoint room equalization

In this paper, an acoustic model for the robustness analysis of optimal multipoint room equalization is proposed. The optimal multipoint equalization aims to have the optimal performance in a least-squares sense for all measured points. The model can be used for theoretical robustness estimation depending on the critical design parameters such as the number of measurement points, the distance between measurements, or the frequency before applying real equalization system. The analysis results show that it is important to set the appropriate number of measurement points and the distances between measurement points to ensure the enlarged equalization region at a specific frequency.     

Construction of Coarse-Grained Models by Reproducing Equilibrium Probability Density Function

The present work proposes a novel methodology for constructing coarse-grained(CG) models, which aims at minimizing the difference between CG model and the corresponding original system. The difference is defined as a functional of their equilibrium conformational probability densities, then is estimated from equilibrium averages of many independent physical quantities denoted as basis functions. An orthonormalization strategy is adopted to get the independent basis functions from sufficiently preselected interesting physical quantities of the system. Thus the current method is named as probability density matching coarse-graining(PMCG) scheme, which effectively takes into account the overall characteristics of the original systems to construct CG model, and it is a natural improvement of the usual CG scheme wherein some physical quantities are intuitively chosen without considering their correlations. We verify the general PMCG framework in constructing a one-site CG water model from TIP3 P model. Both structure of liquids and pressure of the TIP3 P water system are found to be well reproduced at the same time in the constructed CG model.     

Information Invariance and Quantum Probabilities

We consider probabilistic theories in which the most elementary system, a two-dimensional system, contains one bit of information. The bit is assumed to be contained in any complete set of mutually complementary measurements. The requirement of invariance of the information under a continuous change of the set of mutually complementary measurements uniquely singles out a measure of information, which is quadratic in probabilities. The assumption which gives the same scaling of the number of degrees of freedom with the dimension as in quantum theory follows essentially from the assumption that all physical states of a higher dimensional system are those and only those from which one can post-select physical states of two-dimensional systems. The requirement that no more than one bit of information (as quantified by the quadratic measure) is contained in all possible post-selected two-dimensional systems is equivalent to the positivity of density operator in quantum theory. This article is dedicated to Pekka Lahti on the occasion of his 60th birthday.     

Conservation Quantities of the Explicit Symplectic Scheme for Time-evolution of Quantum System

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Monitoring of electrostatic fire and explosion hazards at the inlet to electrostatic precipitators

The paper deals with the continuous monitoring of electrostatic fire and explosion hazards that can occur at the inlet to electrostatic precipitators (ESPs) when highly charged dust particles are transported by a gas carrier that can be the mixtures of both incombustible and combustible flue gases. The risk of ignition and even explosion is especially high in the presence of an explosive mixture of oxygen and, e.g., hydrocarbons, carbon monoxide, etc. To avoid the danger of electrostatic discharges and their consequences for a whole installation including an electrostatic precipitator a method and a specially designed and built system should effectively enable the continuous monitoring of the hazards and should immediately manage any automatic control system or some other control elements. Some theoretical considerations concerning the method proposed, the physical quantities that must be measured, and the derivation of a novel dynamic safety criterion for assessing the risk of hazardous electrostatic discharges are presented. Finally, the author presents and discusses the possible practical application of the microprocessor-based measuring system verified experimentally in the past to the continuous monitoring of the hazards and to the management of an automatic control system to be put into operation. The paper presents a certain idea and proposal of the problem's solution based on the author's many years' experience in the field of pneumatic transport of dusts, powders and granular materials, of the electrostatic measurements of electric and mechanical quantities characteristic of the particulate transport, and of the risk and prevention of discharges of static electricity in transporting pipes and silos, vessels, etc.     

用Radon变换处理非圆截面等离子体的测量结果

本文试图探索一条途径,通过弦测量迅速定出非圆截面等离子体的磁场位形,同时重构出待测物理量的二维分布。假设位形为同心相似的嵌套、分布为磁面的函数,从Radon变换出发,导出了三种方法,不失一般性,着重对D形截面的情形进行了解析推导和计算机模拟,讨论了综合处理多种弦测量的可行性,模拟了利用软X射线和微波同时测量,一次性定出磁场位形和电子温度、电子密度分布的过程。 关键词：     

Acoustic reconstruction of the velocity field in a furnace using a characteristic flow model

An acoustic method can provide a noninvasive, efficient and full-field reconstruction of aerodynamic fields in a furnace. A simple yet reasonable model is devised for reconstruction of a velocity field in a cross section of a tangential furnace from acoustic measurements based on typical physical characteristics of the field. The solenoidal component of the velocity field is modeled by a curved surface, derived by rotating a curve of Gaussian distribution, determined by six characteristic parameters, while the nonrotational component is governed by a priori knowledge. Thus the inverse problem is translated into determination of the characteristic parameters using a set of acoustic projection data. First numerical experiments were undertaken to simulate the acoustic measurement, so as to preliminarily validate the effectiveness of the model. Based on this, physical experiments under different operating conditions were performed in a pilot-scale setup to provide a further test. Hot-wire anemometry and strip floating were applied to compare with acoustic measurements. The acoustic measurements provided satisfactory consistency with both of these approaches. Nevertheless, for a field with a relatively large magnitude of air velocities, the acoustic measurement can give more reliable reconstructions. Extension of the model to measurements of hot tangential furnaces is also discussed.     

Restoration of the signal and its spectral characteristics with an irregular set of measurements

An extension of the algorithm for singular value decomposition (SVD)-based restoration of the signal is suggested that makes it possible to gain information on the dynamics of spectral lines (response of the medium) recorded in a single series of irregular measurements of the signal’s integral characteristics with the help of a sliding window. The size and displacement of the window fluctuate in time. SVD-based restoration is accomplished both directly from irregular measurement data and after interpolation of the data to the nodes of a regular grid. An algorithm of signal restoration that is based on spline interpolation is also proposed. When combined with SVD-based restoration, this algorithm allows almost complete elimination of spurious frequencies. In the case of integral measurements using an irregular-size window with its center displaced, the signal restoration quality and determination of the spectral line dynamics are shown to be no worse than in the case of fluctuation-free measurements. Analysis is performed both for a model signal and for the real response considered earlier in the physical experiment.     

Information-theoretical properties of a sequence of quantum nondemolition measurements

The information-theoretical properties of a sequence of quantum nondemolition measurements are investigated in detail. It is found that the information gain by quantum nondemolition measurement is equal to the entropy decrease of the measured physical system. Under certain conditions, the complete information about a discrete observable of the physical system can be obtained when a sufficiently large number of measurements are performed.     

On the equivalence of the Fröhlich and the Bloch approaches to the electron-phonon coupling

It is shown that the Fröhlich approach for calculating electron-phonon coupling constants based on wave functions moving with the vibrating atoms can be set on a rigorous basis. This approach and the Bloch approach are shown to lead to the same physical results provided that one stays within the adiabatic approximation and considers both first and second order vertices (in the harmonic approximation). Advantages of the Fröhlich approach in past and in possible future calculations are discussed.     

Method for describing the steady-state reaction front in a two-dimensional flow

It has been shown that the complete system of hydrodynamic equations describing the position of the steady-state reaction front in a two-dimensional incompressible flow can be reduced to a closed system of surface equations using the method for reducing the dimension in overdetermined systems of differential equations. This system of surface equations allows the determination of the position of the steady-state front and all other quantities characterizing a hydrodynamic flow through it.     

Quantum computation with vibrationally excited molecules

A new physical implementation for quantum computation is proposed. The vibrational modes of molecules are used to encode qubit systems. Global quantum logic gates are realized using shaped femtosecond laser pulses which are calculated applying optimal control theory. The scaling of the system is favorable; sources for decoherence can be eliminated. A complete set of one- and two-quantum gates is presented for a specific molecule. Detailed analysis regarding experimental realization shows that the structural resolution of today's pulse shapers is easily sufficient for pulse formation.     

Microscopic nuclear collective motion studied by classical equations of motion

The time-dependent variation principle is used to obtain generally non-canonical equations of motion from any class of quantum states which are parameterized by a set of continuous complex quantities. A class of states is presented whose associated classical dynamics is described by the five collective quadrupole degrees of freedom. Information about the classical dynamics of the system can be obtained from the non-canonical equations by finding physically interesting quantities which are coordinate independent and which characterize the low-energy collective motion. Approximate collective hamiltonians, of either a Bohr-Mottelson or an IBM type, can be found by insisting that the interesting physical quantities which describe the low-energy classical behavior of the many-body system are the same as those describing the classical behavior of the system given by the collective hamiltonian. The method is applied to two simple schematic models, one vibrational and one rotational, and IBM hamiltonians are obtained.     

The ladder complete set and relativistic generalizations

The ladder complete set and connected with it a classification scheme correspond to a rest system. With the help of the group U(6,6) · T(143), their corresponding relativistic generalizations are proposed in the present paper, for which purpose a suitable representation of its algebra is examined, and many-dimensional momenta and angular momenta are introduced. An intermediate complete set from commuting operators is formed from the latter (an analogy with the case of the ladder representation is at hand) and the manner for extract of the physical part of the considered space is shown. That gives a possibility to form a physical complete set, that includes also the four-momentum, and in a rest system reduces to the ladder set.