Critical experiments analysis by ABBN-90 constant system
Tsiboulia, A.; Nikolaev, M.N.; Golubev, V. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)] [and others
1997-06-01
The ABBN-90 is a new version of the well-known Russian group-constant system ABBN. Included constants were calculated based on files of evaluated nuclear data from the BROND-2, ENDF/B-VI, and JENDL-3 libraries. The ABBN-90 is intended for the calculation of different types of nuclear reactors and radiation shielding. Calculations of criticality safety and reactivity accidents are also provided by using this constant set. Validation of the ABBN-90 set was made by using a computerized bank of evaluated critical experiments. This bank includes the results of experiments conducted in Russia and abroad of compact spherical assemblies with different reflectors, fast critical assemblies, and fuel/water-solution criticalities. This report presents the results of the calculational analysis of the whole collection of critical experiments. All calculations were produced with the ABBN-90 group-constant system. Revealed discrepancies between experimental and calculational results and their possible reasons are discussed. The codes and archives INDECS system is also described. This system includes three computerized banks: LEMEX, which consists of evaluated experiments and their calculational results; LSENS, which consists of sensitivity coefficients; and LUND, which consists of group-constant covariance matrices. The INDECS system permits us to estimate the accuracy of neutronics calculations. A discussion of the reliability of such estimations is finally presented. 16 figs.
Critical experiments analysis by ABBN-90 constant system
The ABBN-90 is a new version of the well-known Russian group-constant system ABBN. Included constants were calculated based on files of evaluated nuclear data from the BROND-2, ENDF/B-VI, and JENDL-3 libraries. The ABBN-90 is intended for the calculation of different types of nuclear reactors and radiation shielding. Calculations of criticality safety and reactivity accidents are also provided by using this constant set. Validation of the ABBN-90 set was made by using a computerized bank of evaluated critical experiments. This bank includes the results of experiments conducted in Russia and abroad of compact spherical assemblies with different reflectors, fast critical assemblies, and fuel/water-solution criticalities. This report presents the results of the calculational analysis of the whole collection of critical experiments. All calculations were produced with the ABBN-90 group-constant system. Revealed discrepancies between experimental and calculational results and their possible reasons are discussed. The codes and archives INDECS system is also described. This system includes three computerized banks: LEMEX, which consists of evaluated experiments and their calculational results; LSENS, which consists of sensitivity coefficients; and LUND, which consists of group-constant covariance matrices. The INDECS system permits us to estimate the accuracy of neutronics calculations. A discussion of the reliability of such estimations is finally presented. 16 figs
ZEMO system for generating group constants
The code system ZEMO for generating 26 group and 140-group constant sets for fast breeder reactors neutronics is considered. Group constant libraries, calculational techniques, formats of generated group constant sets and code control parameters are described. Results of one-dimensional model calculations for some critical assemblies and results of investigation of sodium void reactivity effect calculational error caused by 26-group approximation for two-dimensional model of BN-800 are presented. 14 refs.; 1 fig.; 3 tabs
Electromechanical systems generating constant frequency alternating current
Т.А. Мазур
2008-01-01
Full Text Available In the article we consider the usage of electromechanical drivers of constant speed rotation, which is based on many stepped electrodynamic reduction unit, in onboard main systems of electric supply of alternative current with constant frequency.
21 CFR 1250.42 - Water systems; constant temperature bottles.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Water systems; constant temperature bottles. 1250...; constant temperature bottles. (a) The water system, whether of the pressure or gravity type, shall be... at all times as to prevent contamination of the water. (e) Constant temperature bottles and...
New multitarget constant modulus array for CDMA systems
Zhang Jidong; Zheng Baoyu
2006-01-01
A new multitarget constant modulus array is proposed for CDMA systems based on least squares constant modulus algorithm. The new algorithm is called pre-despreading decision directed least squares constant modulus algorithm (DDDLSCMA). In the new algorithm, the pre-despreading is first applied for multitarget arrays to remove some multiple access signals, then the despreaded signal is processed by the algorithm which united the constant modulus algorithm and decision directed method. Simulation results illustrate the good performance for the proposed algorithm.
An automatic system for crystal growth studies at constant supersaturation
March, J. G.; Costa-Bauzá, A.; F. Grases; Söhnel, O.
1992-01-01
An automatic system for growing crystals from seeded supersaturated solutions at constant supersaturation is described. Control of burettes and data acquisition are controlled by computer. The system was tested with a study of the calcium oxalate kinetics of crystal growth.
A new version of the unified constant system package
A unified constant retrieval system called OKS has been developed for convenient access to the constant systems ARAMAKO-2F, ARAMAKO-G, DENSTY, TERMAC and others, in calculating radiation transport, value functions and various functionals. Since the system was first developed in 1980 both its language and its functional contents have been improved and added to. In this paper the input language and performance of the new version are described. (author)
Constant depression fan system a novel glovebox ventilation system
In a conventional glovebox ventilation system the depression within the glovebox under normal operation is controlled by instrumentation. In the event of a breach the pressure within the box rises to atmospheric pressure, this pressure rise is detected by instrumentation which in turn operates a quick opening damper in a high depression extract to achieve a 1 metre/sec (200 fpm) inflow through the breach, which can take up to 2 seconds to establish. This system, although widely used, suffers from two distinct drawbacks: It takes a finite time to achieve the containment velocity of 1 metre/sec. It relies upon instrumentation to achieve its objectives. A new glovebox ventilation system has been developed by AWE to overcome these drawbacks. This is the Constant Depression Fan System (CDFS) which is based on an extract fan with a flat characteristic. This achieves all the requirements for the ventilation of gloveboxes and has the advantages that: It has only one moving part - the extract fan. It requires NO INSTRUMENTATION to achieve its objectives. It achieves the containment velocity of 1 metre/sec in the shortest possible time - approximately 0.2 seconds - and tests have shown that containment is maintained under breach conditions. Thus the CDFS is SAFER, SIMPLER and MORE RELIABLE
Fission Product Fast Reactor Constants System of JNDC
The Fission Product Fast Reactor Constants System of JNDC has been developed for providing the FP group constants set rather automatically from the Japanese Evaluated Nuclear Data Library (JENDL). In the present version, the evaluation by JNDC was adopted for the 28 important nuclides and the evaluation by Cook was supplementally used for the other nuclides to obtain the lumped group constants. The burn-up time dependence of the lumped constants were examined. The change of capture cross sections are about 5% between 60 days and 720 days of burn-up for any type of fast reactors. The 28 important nuclides take more than 80% of total capture by fission products and cover 40% of elastic scattering and 60% of inelastic scattering. The JNDC FP lumped constants were compared with those based on Cook's evaluation and on the ENDF/B-4. The discrepancies among the three are 15% for capture and 10% for both of elastic and inelastic scattering. A benchmark test was performed using the integral measurements made in RCN, Petten, the Netherlands, in order to check the reliability of the JNDC FP group constants. The JNDC constants give better agreements than the Cook and ENDF/B-4 constants with the experiments both for FP mixtures and for separated isotopes. (auth.)
Assessment of fast radiographic systems by the constant exposure technique
The constant exposure technique was applied to compare the radiographic image quality and relative speed of different fast radiographic systems. Conventional industrial X-ray films, exposed with lead intensifying screens, special fast film with fluorometallic screens as well as different brands of radiographic paper exposed both with fluorescent as well as fluorometallic screens were tested and compared. ISO wire IQI's and ASTM penetrameters were used together with 30-mm aluminium and 10-mm steel plates. For all the fast radiographic systems wire sensitivity better than 2 per cent was obtained. The constant exposure technique proved to be adequate for the assessment of fast radiographic systems. (author)
Constant-space P systems with active membranes
A. Leporati; Manzoni, L; Mauri, G; Porreca, A; Zandron, C
2014-01-01
We show that a constant amount of space is sufficient to simulate a polynomial-space bounded Turing machine by P systems with active membranes. We thus obtain a new characterisation of PSPACE, which raises interesting questions about the definition of space complexity for P systems. We then propose an alternative definition, where the size of the alphabet and the number of membrane labels of each P system are also taken into account. Finally we prove that, when less than a logarithmic number ...
PARALLEL EVALUATION OF CONSTANT AND DIURNAL FLOW TREATMENT SYSTEMS
Pilot plant studies were performed to evaluate the effects of an imposed diurnal flow pattern on a conventional activated sludge treatment plant. These results were compared against data generated on a similar system treating a constant flow. Effects on primary clarifier and fina...
Research of digital constant fraction discriminator in PET system
The research on digital constant fraction discriminator of spike pulse signal in PET detector is introduced. Based on FPGA technique, rapid signal's time information is extracted via DCFD algorithm after a high-speed ADC digitization. Experiment results show that time resolution of DCFD is 772 ps, which meets the requirement of time measurement in PET system well. (authors)
Constant-Space P Systems with Active Membranes
Leporati, Alberto; Manzoni, Luca; Mauri, Giancarlo; Porreca, Antonio E.; Zandron, Claudio; Research Group on Natural Computing (Universidad de Sevilla) (Coordinador)
2014-01-01
We continue the investigation of the computational power of space- constrained P systems. We show that only a constant amount of space is needed in order to simulate a polynomial-space bounded Turing machine. Due to this result, we propose an alternative de nition of space complexity for P systems, where the amount of information contained in individual objects and membrane labels is also taken into ac- count. Finally, we prove that, when less than a logarithmic number of membr...
Spectral Gap and Logarithmic Sobolev Constant for Continuous Spin Systems
Mu Fa CHEN
2008-01-01
The aim of this paper is to study the spectral gap and the logarithmic Sobolev constant for continuous spin systems. A simple but general result for estimating the spectral gap of finite dimensional systems is given by Theorem 1.1, in terms of the spectral gap for one-dimensional marginals. The study of this topic provides us a chance, and it is indeed another aim of the paper, to justify the power of the results obtained previously. The exact order in dimension one (Proposition 1.4), and then the precise leading order and the explicit positive regions of the spectral gap and the logarithmic Sobolev constant for two typical infinite-dimensional models are presented (Theorems 6.2 and 6.3). Since we are interested in explicit estimates, the computations become quite involved. A long section (Section 4) is devoted to the study of the spectral gap in dimension one.
Bifurcation in a Discrete-Time Piecewise Constant Dynamical System
Chenmin Hou
2013-01-01
Full Text Available The study of recurrent neural networks with piecewise constant transition or control functions has attracted much attention recently because they can be used to simulate many physical phenomena. A recurrent and discontinuous two-state dynamical system involving a nonnegative bifurcation parameter is studied. By elementary but novel arguments, we are able to give a complete analysis on its asymptotic behavior when the parameter varies from 0 to . It is hoped that our analysis will provide motivation for further results on large-scale recurrent McCulloch-Pitts-type neural networks and piecewise continuous discrete-time dynamical systems.
Controllability and Observability Criteria for Linear Piecewise Constant Impulsive Systems
Hong Shi
2012-01-01
Full Text Available Impulsive differential systems are an important class of mathematical models for many practical systems in physics, chemistry, biology, engineering, and information science that exhibit impulsive dynamical behaviors due to abrupt changes at certain instants during the dynamical processes. This paper studies the controllability and observability of linear piecewise constant impulsive systems. Necessary and sufficient criteria for reachability and controllability are established, respectively. It is proved that the reachability is equivalent to the controllability under some mild conditions. Then, necessary and sufficient criteria for observability and determinability of such systems are established, respectively. It is also proved that the observability is equivalent to the determinability under some mild conditions. Our criteria are of the geometric type, and they can be transformed into algebraic type conveniently. Finally, a numerical example is given to illustrate the utility of our criteria.
Macroscopic multigroup constants for accelerator driven system core calculation
The high-level wastes stored in facilities above ground or shallow repositories, in close connection with its nuclear power plant, can take almost 106 years before the radiotoxicity became of the order of the background. While the disposal issue is not urgent from a technical viewpoint, it is recognized that extended storage in the facilities is not acceptable since these ones cannot provide sufficient isolation in the long term and neither is it ethical to leave the waste problem to future generations. A technique to diminish this time is to transmute these long-lived elements into short-lived elements. The approach is to use an Accelerator Driven System (ADS), a sub-critical arrangement which uses a Spallation Neutron Source (SNS), after separation the minor actinides and the long-lived fission products (LLFP), to convert them to short-lived isotopes. As an advanced reactor fuel, still today, there is a few data around these type of core systems. In this paper we generate macroscopic multigroup constants for use in calculations of a typical ADS fuel, take into consideration, the ENDF/BVI data file. Four energy groups are chosen to collapse the data from ENDF/B-VI data file by PREPRO code. A typical MOX fuel cell is used to validate the methodology. The results are used to calculate one typical subcritical ADS core. (author)
Solar System motions and the cosmological constant: a new approach
Iorio, Lorenzo
2007-01-01
In this paper we use the corrections to the Newton-Einstein secular precessions of the perihelia of some planets (Mercury, Earth, Mars, Jupiter, Saturn) of the Solar System, phenomenologically estimated as solve-for parameters by the Russian astronomer E.V. Pitjeva in a global fit of almost one century of data with the EPM2004 ephemerides, in order to put on the test the expression for the perihelion precession induced by an uniform cosmological constant $\\Lambda$ in the Schwarzschild-de Sitter (or Kottler) space-time. We compare such an extra-rate to the estimated corrections to the planetary perihelion precessions by taking their ratio for different pairs of planets instead of using one perihelion at a time for each planet separately, as done so far in literature. The answer is neatly negative, even by further re-scaling by a factor 10 (and even 100 for Saturn) the errors in the estimated extra-precessions of the perihelia released by Pitjeva. However, caution is advised because it would be relevant to repe...
A Piecewise-Conserved Constant of Motion for a Dissipative System
Burko, Lior M.
1999-01-01
We discuss a piecewise-conserved constant of motion for a simple dissipative oscillatory mechanical system. The system is a harmonic oscillator with sliding (dry) friction. The piecewise-conserved constant of motion corresponds to the time average of the energy of the system during one half-period of the motion, and changes abruptly at the turning points of the motion. At late times the piecewise-conserved constant of motion degenerates to a constant of motion in the usual sense.
One-dimensional relativistic dissipative system with constant force and its quantization
López, Gustavo; López, Xaman-Ek; Hernández, Hector
2005-01-01
For a relativistic particle under a constant force and a linear velocity dissipation force, a constant of motion is found. Problems are shown for getting the Hamiltoninan of this system. Thus, the quantization of this system is carried out through the constant of motion and using the quantization of the velocity variable. The dissipative relativistic quantum bouncer is outlined within this quantization approach.
Constant of Motion for One-Diemnsional Non Autonomous Linear Systems and Harmonic Oscillator
Lopez, Gustavo
1999-01-01
For a one-dimensional motion, a constant of motion for non autonomous an linear system (position and velocity) is given from the constant of motion associated to its autonomous system. This approach is used in the study of the harmonic oscillator with an additional time depending force.
A short description is given of the Russian evaluated neutron data library FOND-2.2. The main purpose of FOND-2.2 is to provide sets of constants for the ABBN constants system. A history of its compilation and the sources of the neutron data are given. The contents of FOND-2.2 are presented with brief comments. (author)
Comment on "Global Positioning System Test of the Local Position Invariance of Planck's Constant"
Berengut, J C
2012-01-01
In their Letter, Kentosh and Mohageg [Phys. Rev. Lett. 108, 110801 (2012)] seek to use data from clocks aboard global positioning system (GPS) satellites to place limits on local position invariance (LPI) violations of Planck's constant, h. It is the purpose of this comment to show that discussing limits on variation of dimensional constants (such as h) is not meaningful; that even within a correct framework it is not possible to extract limits on variation of fundamental constants from a single type of clock aboard GPS satellites; and to correct an important misconception in the authors' interpretation of previous Earth-based LPI experiments.
Decay constants of subcritical system by diffusion theory for two groups
The effects of a neutronic pulse applied to a subcritical multiplicative medium are analysed on the basis of the diffusion theory for one and two groups. The decay constants of the system for various values of geometric buckling were determined from the experimental data. A natural uranium-light water lattice was pulsed employing a Texas Nuclear 9905 neutron generator. The least square method was employed in the data reduction procedures to determine the decay constants. The separation of the decay constants associated with thermal and epithermal fluxes is attempted through two groups formulation. (author)
Decay constants of a subcritical system by two-group diffusion theory
The effects of a neutronic pulse applied to a subcritical multiplicative medium are analyzed on the basis of the diffusion theory for one and two groups. The decay constants of the system were determined from the experimental data, for various values geometric buckling. A natural uranium light-water configuration was pulsed employing a Texas Nuclear 9905 neutron generator. The least square method was employed in the data reduction procedures to determine the decay constants. The separation of the decay constants associated with thermal and epithermal fluxes are verified through two groups formulation. (Author)
ℋ∞ constant gain state feedback stabilization of stochastic hybrid systems with Wiener process
E. K. Boukas
2004-01-01
Full Text Available This paper considers the stabilization problem of the class of continuous-time linear stochastic hybrid systems with Wiener process. The ℋ∞ state feedback stabilization problem is treated. A state feedback controller with constant gain that does not require access to the system mode is designed. LMI-based conditions are developed to design the state feedback controller with constant gain that stochastically stabilizes the studied class of systems and, at the same time, achieve the disturbance rejection of a desired level. The minimum disturbance rejection is also determined. Numerical examples are given to show the usefulness of the proposed results.
Perturbation approach and the constant of motion for on-dimensional dynamical systems
A perturbation technic is used to find the constant of motion of a one-dimensional autonomous system. The convergence of the method is discussed through some examples. In addition, the approach is extended to one-dimensional non-autonomous systems where some examples are given
Boyko, Vyacheslav M; Popovych, Roman O; Shapoval, Nataliya M
2013-01-01
Lie symmetries of systems of second-order linear ordinary differential equations with constant coefficients are exhaustively described over both the complex and real fields. The exact lower and upper bounds for the dimensions of the maximal Lie invariance algebras possessed by such systems are obtained using an effective algebraic approach. PMID:23564972
The Measurement of the Hubble Constant H_0 in the Solar System
Anderson, Allen Joel
2010-01-01
This paper discusses the methodology necessary to measure the Hubble constant Ho to a high degree of accuracy based upon Doppler tracking of spacecraft in the solar system. Using this methodology with available published data we determine a model independent value of the Hubble constant for the current epoch in the solar system to be Ho = 2.59 \\pm 0.05 x 10^-18 (s^-1) or as 79.8 \\pm 1.7 (km/s/Mpc). We calculate the direct effect of the Cosmic Redshift on Doppler tracking of spacecraft in the ...
Bracken, Paul
2007-05-01
The generalized Weierstrass (GW) system is introduced and its correspondence with the associated two-dimensional nonlinear sigma model is reviewed. The method of symmetry reduction is systematically applied to derive several classes of invariant solutions for the GW system. The solutions can be used to induce constant mean curvature surfaces in Euclidean three space. Some properties of the system for the case of nonconstant mean curvature are introduced as well.
One operational amplifier simulator for third order systems with a leading time constant
L. K. Wadhwa
1963-01-01
Full Text Available The paper outlines a method for the simulation of third order linear systems with only one operational amplifier. A particular class of the general third order systems, that is, systems with a leading time constant is considered in this paper. A basic circuit consisting of one operational amplifier, four capacitors and five resistors is presented. The circuit is a analyzed and the conditions of physical reliability discussed and obtained. The design formulae and procedure are also given.
The Control System Simulation of Variable-Speed Constant-Frequency Wind Turbine
窦金延; 曹娜
2010-01-01
<正>In general,Variable-Speed Constant Frequency (VSCF)Wind generation system is controlled by stator voltage orientation method which based on the mathematic model of VSCF Wind generation system and discussed the control strategy.Present the whole dynamic control model of variable-speed wind generator system in MATLAB/ Simulink,and the simulation results confirm the validity and effectiveness of the proposed control strategy.
A one-vessel crystal growth system has been built to grow KD P crystals of up to 10 cm in length. The process is based on transfer of saturated solution under constant temperature-constant supersaturation. Ca ry 17 D X spectrophotometer transmission spectra from (100) planes of the grown crystals show 89% transmission in the visible region. The system provides a reduction in capping time and growth rate of 25 mm/day for the first day and 1.5 mm/day for the 7th day
Optimal Control of Production-Inventory Systems with Constant and Compound Poisson Demand
Germs, Remco; Foreest, Nicky D. van
2014-01-01
In this paper, we study a production-inventory systems with finite production capacity and fixed setup costs. The demand process is modeled as a mixture of a compound Poisson process and a constant demand rate. For the backlog model we establish conditions on the holding and backlogging costs such t
Library of neutron reaction cross-sections in the ABBN-93 constant system
The library of neutron reaction group cross-sections in the ABBN-93 constant set is described. The format used for data representation, the content and purpose of the sub-libraries and their practical application in the SCALE criticality safety estimation system are discussed. (author)
Bonanno, Alfio
2011-01-01
We discuss a mechanism that induces a time-dependent vacuum energy on cosmological scales. It is based on the instability induced renormalization triggered by the low energy quantum fluctuations in a Universe with a positive cosmological constant. We employ the dynamical systems approach to study the qualitative behavior of Friedmann-Robertson-Walker cosmologies where the cosmological constant is dynamically evolving according with this nonperturbative scaling at low energies. It will be shown that it is possible to realize a "two regimes" dark energy phases, where an unstable early phase of power-law evolution of the scale factor is followed by an accelerated expansion era at late times.
The model of the variable speed constant frequency closed-loop system operating in generating state
Ding, Daohong
1986-10-01
The variable speed constant frequency (USCF) electrical power system is a new type of aircraft power supply, which contains an alternating generator and a cycloconverter. This sums up the work of the cycloconverter and obtains four fundamental classes of circuit construction of the closed-loop system, which have twelve operating models. A mathematical model for each fundamental class of the circuit construction is introduced. These mathematical models can be used in digital simulation.
A new constant-pressure molecular dynamics method for finite system
Sun, D. Y.; Gong, X. G.
2001-01-01
In this letter, by writing the volume as a function of coordinates of atoms, we present a new constant-pressure molecular dynamics method with parameters free. This method is specially appropriate for the finite system in which the periodic boundary condition does not exist. Simulations on the carbon nanotube and the Ni nanoparticle clearly demonstrate the validity of the method. By using this method, one can easily obtain the equation of states for the finite system under the external pressure.
Assoc. Prof. Popescu Liviu Ph.D
2010-01-01
The paper deals with the study of a drift less control affine system with positive homogeneous cost of Randers type in the case of bracket generating distribution of no constant rank. We use the Pontryagin Maximum Principle in order to find the general solution. In the particular case of quadratic cost the optimal trajectories of the distributional system are the geodesics of the so called sub-Riemannian geometry.
Rogers, Keith Eric
1994-01-01
The basic concepts of command preshaping were taken and adapted to the framework of systems with constant amplitude (on-off) actuators. In this context, pulse sequences were developed which help to attenuate vibration in flexible systems with high robustness to errors in frequency identification. Sequences containing impulses of different magnitudes were approximated by sequences containing pulses of different durations. The effects of variation in pulse width on this approximation were examined. Sequences capable of minimizing loads induced in flexible systems during execution of commands were also investigated. The usefulness of these techniques in real-world situations was verified by application to a high fidelity simulation of the space shuttle. Results showed that constant amplitude preshaping techniques offer a substantial improvement in vibration reduction over both the standard and upgraded shuttle control methods and may be mission enabling for use of the shuttle with extremely massive payloads.
Herrera, J. I.; Reddoch, T. W.; Lawler, J. S.
1985-01-01
As efforts are accelerated to improve the overall capability and performance of wind electric systems, increased attention to variable speed configurations has developed. A number of potentially viable configurations have emerged. Various attributes of variable speed systems need to be carefully tested to evaluate their performance from the utility points of view. With this purpose, the NASA experimental variable speed constant frequency (VSCF) system has been tested. In order to determine the usefulness of these systems in utility applications, tests are required to resolve issues fundamental to electric utility systems. Legitimate questions exist regarding how variable speed generators will influence the performance of electric utility systems; therefore, tests from a utility perspective, have been performed on the VSCF system and an induction generator at an operating power level of 30 kW on a system rated at 200 kVA and 0.8 power factor.
Anderson, Karl F. (Inventor)
1994-01-01
A constant current loop measuring system is provided for measuring a characteristic of an environment. The system comprises a first impedance positionable in the environment, a second impedance coupled in series with said first impedance and a parasitic impedance electrically coupled to the first and second impedances. A current generating device, electrically coupled in series with the first and second impedances, provides a constant current through the first and second impedances to produce first and second voltages across the first and second impedances, respectively, and a parasitic voltage across the parasitic impedance. A high impedance voltage measuring device measures a voltage difference between the first and second voltages independent of the parasitic voltage to produce a characteristic voltage representative of the characteristic of the environment.
Determination of relaxation constants of multi-level quadrupole spin-system
Possibility to determine relaxation constants of multi-level spin-system all single-quantum transitions under two-frequency effect is studied. By means of two-frequency nuclear quadrupole resonance one determines the times of relaxation for all single-quantum transitions of multi-level quadrupole spin-system on the basis of data on one transition. In this case, the accuracy of determination is equal to the accuracy of measurement of the relaxation times under single-frequency excitation of transition that is taken as a base one. Paper presents data on measurement and determination of relaxation constants using NQR technique in KReO4, NaReO4, as well as, in SbCl3, SbBr3 and in their complexes under various temperatures
Second order sliding power control for a variable speed-constant frequency energy conversion system
This paper presents a decoupled active and reactive power control for a variable speed-constant frequency generation system based on a brushless doubly fed reluctance machine. The control design is approached using multi-input second order sliding techniques which are specially appropriate to deal with nonlinear system models in presence of external disturbances and model inaccuracies. The controller synthesized through this theoretical framework presents very good robustness features, a finite reaching time and a chattering-free behavior. The performance of the closed loop system is assessed through representative computer simulations.
Efficient Disengaging Hooks System Based on Constant-Power Speed Regulation of Frequency Converter
Jianjian Wang; Rongbo Zhu; Chenliang Qian
2013-01-01
In the traditional port, disengaging hook system adopts a three-phase power frequency power to drive a three-phase asynchronous motor. The operation is simple and the maintenance is convenient. However, it still keeps the speed of mooring lines constant. Under the light-load condition, the work efficiency could be affected because of the low speed. To solve this problem, we start the research in speed control of disengaging hook. By using variable frequency control technology to transform the...
Stochastic resonance in a periodic potential system under a constant force
An overdamped particle moving in a periodic potential, and subject to a constant force and a stochastic force (i.e., χ = -sin(2πχ) + B + Γ(t),Γ(t) is a white noise) is considered. The mobility of the particle, d/dt, is investigated. The stochastic resonance type of behaviour is revealed. The study of the SR problem can thus be extended to systems with periodic force. (author). 13 refs
SINR evaluation of OFDM-CDMA systems with constant timing offset: asymptotic analysis
Nasser, Youssef; des Noes, Mathieu; Ros, Laurent; Jourdain, Geneviève
2005-01-01
This article presents the impact of a constant timing error on the performance of a downlink 2 dimensional spreading OFDM-CDMA system. This impact is measured by the Signal to Interference plus Noise Ratio (SINR) degradation after equalization and despreading. Using random matrix theory, an asymptotic evaluation of the SINR is obtained. It is independent of the value of users' spreading code while taking into account their orthogonality. Simulation results are provided to evaluate and discuss...
Efficient Disengaging Hooks System Based on Constant-Power Speed Regulation of Frequency Converter
Jianjian Wang
2013-04-01
Full Text Available In the traditional port, disengaging hook system adopts a three-phase power frequency power to drive a three-phase asynchronous motor. The operation is simple and the maintenance is convenient. However, it still keeps the speed of mooring lines constant. Under the light-load condition, the work efficiency could be affected because of the low speed. To solve this problem, we start the research in speed control of disengaging hook. By using variable frequency control technology to transform the original system and using frequency converter to carry on the constant-power speed regulation, technicians also adopt vector control algorithm with PG to achieve adjustable speed of cable volume. The motor is under no load or light load state with high-speed after starting and turns into low-speed through full load. It makes motor stay in constant-power state when it works. This design solves the low-efficiency of disengaging hook in the past and makes system achieve adjustable motor speed. In this design and application, not only can technicians reduce the initial cost, but also they can reduce operating costs markedly by adopting energy-saving control equipment at the same time.
TIMS-PGG: a code system for producing group constants in fast neutron energy region
The TIMS-PGG code system has been developed for calculating group constants in fast neutron energy region by processing the nuclear data files compiled with the ENDF/B-IV format. In this code system, the group constant for light and medium weight nuclei and for the smooth cross sections of heavy nuclei are calculated by weighting either ''1/E and fission spectra'' or ''collision density spectrum'', using the PROF.GROUCH.GIIR/code. For resonant nuclei, the TIMS-1 code which solves exactly the neutron slowing down equation is used. The calculated infinitely dilute cross sections, resonance shielding factors, scattering transfer matrices and fission spectra are weitten to ''Master file'' with the PDS format. From the Master file, depending on user's object, a user library is produced by using the utility code LIBMAKE. The present report describes the user's manual of the TIMS-PGG code system and the generation method of group constants library. Moreover, the user's manual of the code is described for fast reactor benchmark tests. (author)
A Novel Constant-Pressure Pumped Hydro Combined with Compressed Air Energy Storage System
Erren Yao
2014-12-01
Full Text Available As intermittent renewable energy is receiving increasing attention, the combination of intermittent renewable energy with large-scale energy storage technology is considered as an important technological approach for the wider application of wind power and solar energy. Pumped hydro combined with compressed air energy storage system (PHCA is one of the energy storage systems that not only integrates the advantages but also overcomes the disadvantages of compressed air energy storage (CAES systems and pumped hydro energy storage systems to solve the problem of energy storage in China’s arid regions. Aiming at the variable working conditions of PHCA system technology, this study proposes a new constant-pressure PHCA. The most significant characteristics of this system were that the water pump and hydroturbine work under stable conditions and this improves the working efficiency of the equipment without incurring an energy loss. In addition, the constant-pressure PHCA system was subjected to energy and exergy analysis, in expectation of exploring an attractive solution for the large-scale storage of existing intermittent renewable energy.
The measurement system of birefringence and Verdet constant of optical fiber
Huang, Yi; Chen, Li; Guo, Qiang; Pang, Fufei; Wen, Jianxiang; Shang, Yana; Wang, Tingyun
2013-12-01
The Faraday magneto-optical effect of optical fiber has many applications in monitoring magnetic field and electric current. When a linearly polarized light propagates in the direction of a magnetic field, the plane of polarization will rotate linearly proportional to the strength of the applied magnetic field, which following the relationship of θF =VBl. θF is the Faraday rotation angle, which is proportional to the magnetic flux density B and the Verdet constant V . However, when the optical fiber contains the effect of linear birefringence, the detection of Faraday rotation angle will depend on the line birefringence. In order to determine the Verdet constant of an optical fiber under a linear birefringence, the fiber birefringence needs to be accurately measured. In this work, a model is applied to analyze the polarization properties of an optical fiber by using the Jones matrix method. A measurement system based on the lock-in amplifier technology is designed to test the Verdet constant and the birefringence of optical fiber. The magnetic field is produced by a solenoid with a DC current. A tunable laser is intensity modulated with a motorized rotating chopper. The actuator supplies a signal as the phase-locked synchronization reference to the signal of the lock-in amplifier. The measurement accuracy is analyzed and the sensitivity of the system is optimized. In this measurement system, the Verdet constant of the SMF-28 fiber was measured to be 0.56±0.02 rad/T·m at 1550nm. This setup is well suitable for measuring the high signal-to-noise ratio (SNR) sensitivity for lock-in amplifier at a low magnetic field strength.
An alternative method to Mariotte reservoir system for maintaining constant hydraulic pressure
Some studies being done to evaluate the suitability of the Yucca Mountain area as a potential radioactive waste repository require the application of a constant water pressure as a boundary condition to study water flow through porous media. The Mariotte reservoir system is commonly used to supply such a boundary condition. Several problems with the Mariotte reservoir system were discovered when it was used to apply a constant water pressure as a boundary condition for a prolonged period. The constant-pressure boundary condition is required for some lab. experiments to study water flow through porous media. The observed problems were caused by temperature and barometric-pressure fluctuations while the flow rates were very small and caused erroneous water flow-rate measurements. An alternative method was developed and used where the water pressure is controlled by regulating its level by using water-level sensing electrodes. The new method eliminated the effects of temperature and barometric-pressure fluctuations and maintained an acceptable accuracy of the estimated water flow rate without compromising the advantage of the Mariotte reservoir
High-Performance Constant Power Generation in Grid-Connected PV Systems
Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede
2016-01-01
An advanced power control strategy by limiting the maximum feed-in power of PV systems has been proposed, which can ensure a fast and smooth transition between maximum power point tracking and Constant Power Generation (CPG). Regardless of the solar irradiance levels, high-performance and stable...... operation are always achieved by the proposed control strategy. It can regulate the PV output power according to any set-point, and force the PV systems to operate at the left side of the maximum power point without stability problems. Experimental results have verified the effectiveness of the proposed CPG...
BLIND EQUALIZATION OF MIMO SYSTEMS BASED ON ORTHOGONAL CONSTANT MODULUS ALGORITHM
无
2006-01-01
This paper investigates adaptive blind source separation and equalization for Multiple Input Mul-tiple Output (MIMO) systems. To effectively recover input signals, remove Inter-Symbol Interference (ISI)and suppress Inter-User Interference (IUI), the array input is first transformed into the signal subspace, thenwith the derived orthogonality between weight vectors of different input signals, a new orthogonal ConstantModulus Algorithm (CMA) is proposed. Computer simulation results illustrate the promising performance ofthe proposed method. Without channel identification, the proposed method can recover all the system inputssimultaneously and can be adaptive to channel changes without prior knowledge about signals.
Stabilization criteria for continuous linear time-invariant systems with constant lags
M. De La Sen
2006-06-01
Full Text Available Some criteria for asymptotic stability of linear and time-invariant systems with constant point delays are derived. Such criteria are concerned with the properties of robust stability related to two relevant auxiliary delay-free systems which are built by deleting the delayed dynamics or considering that the delay is zero. Explicit asymptotic stability results, easy to test, are given for both the unforced and closed-loop systems when the stabilizing controller for one of the auxiliary delay-free systems is used for the current time-delay system. The proposed techniques include frequency domain analysis techniques including the use of HÃ¢ÂˆÂž norms.
Non-constant positive steady-states of a diffusive predator-prey system in homogeneous environment
Ko, Wonlyul; Ryu, Kimun
2007-03-01
In this paper, we investigate the existence and non-existence of non-constant positive steady-states of a diffusive predator-prey interaction system under homogeneous Neumann boundary condition. In homogeneous environment, we show that the predator-prey model with Leslie-Gower functional response has no non-constant positive solution, but the system with a general functional response may have at least one non-constant positive steady-state under some conditions.
Rare events in many-body systems: reactive paths and reaction constants for structural transitions
This PhD thesis deals with the study of fundamental physics phenomena, with applications to nuclear materials of interest. We have developed methods for the study of rare events related to thermally activated structural transitions in many body systems. The first method involves the numerical simulation of the probability current associated with reactive paths. After deriving the evolution equations for the probability current, a Diffusion Monte Carlo algorithm is implemented in order to sample this current. This technique, called Transition Current Sampling was applied to the study of structural transitions in a cluster of 38 atoms with Lennard-Jones potential (LJ-38). A second algorithm, called Transition Path Sampling with local Lyapunov bias (LyTPS), was then developed. LyTPS calculates reaction rates at finite temperature by following the transition state theory. A statistical bias based on the maximum local Lyapunov exponents is introduced to accelerate the sampling of reactive trajectories. To extract the value of the equilibrium reaction constants obtained from LyTPS, we use the Multistate Bennett Acceptance Ratio. We again validate this method on the LJ-38 cluster. LyTPS is then used to calculate migration constants for vacancies and divacancies in the α-Iron, and the associated migration entropy. These constants are used as input parameter for codes modeling the kinetic evolution after irradiation (First Passage Kinetic Monte Carlo) to reproduce numerically resistivity recovery experiments in α-Iron. (author)
Constant Power Generation of Photovoltaic Systems Considering the Distributed Grid Capacity
Yang, Yongheng; Blaabjerg, Frede; Wang, Huai
2014-01-01
increased maintenances introduce new obstacles. In view of this concern, the DSOs starts to reduce PV installations in order to avoid an extension of the power infrastructure. Besides, another alternative solution is to limit the maximum feed-in power of the existing PV systems to a certain level. It can...... contribute to a weakened requirement of grid expansion and at the same time an increased penetration level. Therefore, to meet the need of this emerging ancillary service provided by future PV systems, a Constant Power Generation (CPG) control concept of PV inverters is proposed in this paper. Accordingly......With an imperative demand of clean and reliable electricity generation in some countries, the increasing adoption of new photovoltaic (PV) systems pushes the Distribution System Operators (DSOs) to expand the transmission/distributed lines. However, the potential cost brought by such extensions and...
Optimal Control of Production-Inventory Systems with Constant and Compound Poisson Demand
Germs, Remco; Foreest, Nicky D. van
2014-01-01
In this paper, we study a production-inventory systems with finite production capacity and fixed setup costs. The demand process is modeled as a mixture of a compound Poisson process and a constant demand rate. For the backlog model we establish conditions on the holding and backlogging costs such that the average-cost optimal policy is of (s, S)-type. The method of proof is based on the reduction of the production-inventory problem to an appropriate optimal stopping problem and the analysis ...
Ashtekar, Abhay; Bonga, Béatrice; Kesavan, Aruna
2016-02-01
There is a deep tension between the well-developed theory of gravitational waves from isolated systems and the presence of a positive cosmological constant Λ, however tiny. In particular a generalization of Einstein's 1918 quadrupole formula that would allow a positive Λ is not yet available. We first explain the principal difficulties and then show that it is possible to overcome them in the weak field limit. These results also provide concrete hints for constructing the Λ>0 generalization of the Bondi-Sachs framework for full, nonlinear general relativity. PMID:26894695
Gravitational waves from isolated systems: The phantom menace of a positive cosmological constant
Ashtekar, Abhay; Kesavan, Aruna
2015-01-01
There is a deep tension between the well-developed theory of gravitational waves from isolated systems and the presence of a positive cosmological constant $\\Lambda$, however tiny. In particular, even the post-Newtonian quadrupole formula, derived by Einstein in 1918, has not been generalized to include a positive $\\Lambda$. We first explain the principal difficulties and then show that it is possible to overcome them in the weak field limit. These results also provide concrete hints for constructing the $\\Lambda >0$ generalization of the Bondi-Sachs framework for full, non-linear general relativity.
Blümler, Peter
2015-01-01
A design for a permanent magnet system is proposed that generates spatially homogeneous, constant magnetic field gradients, thus creating conditions suitable for MRI without gradient coils and amplifiers. This is achieved by superimposing a weak Halbach quadrupole on a strong Halbach dipole. Rotation of either the quadrupole or the entire magnet assembly can be used to generate 2D images via filtered back-projection. Additionally, the mutual rotation of two quadrupoles can be used to scale the resulting gradient. If both gradients have identical strength the gradient can even be made to vanish. The concept is demonstrated by analytical considerations and FEM-simulations.
Ashtekar, Abhay; Bonga, Béatrice; Kesavan, Aruna
2016-02-01
There is a deep tension between the well-developed theory of gravitational waves from isolated systems and the presence of a positive cosmological constant Λ , however tiny. In particular a generalization of Einstein's 1918 quadrupole formula that would allow a positive Λ is not yet available. We first explain the principal difficulties and then show that it is possible to overcome them in the weak field limit. These results also provide concrete hints for constructing the Λ >0 generalization of the Bondi-Sachs framework for full, nonlinear general relativity.
Salinas-Rodriguez, Sergio G.
2015-02-18
Reliable methods for measuring and predicting the fouling potential of reverse osmosis (RO) feed water are important in preventing and diagnosing fouling at the design stage, and for monitoring pre-treatment performance during plant operation. The Modified Fouling Index Ultrafiltration (MFI-UF) constant flux is a significant development with respect to assessing the fouling potential of RO feed water. This research investigates (1) the variables influencing the MFI-UF test at constant flux filtration (membrane pore size, membrane material, flux rate); and (2) the application of MFI-UF into pre-treatment assessment and RO fouling estimation. The dependency of MFI on flux, means that to assess accurately particulate fouling in RO systems, the MFI should be measured at a flux similar to a RO system (close to 20 L/m2/h) or extrapolated from higher fluxes. The two studied membrane materials showed reproducible results; 10% for PES membranes and 6.3% for RC membranes. Deposition factors (amount of particles that remain on the surface of membrane) were measured in a full-scale plant ranging between 0.2 and 0.5. The concept of “safe MFI” is presented as a guideline for assessing pre-treatment for RO systems.
Wang, Shilong; Yin, Changchun; Lin, Jun; Yang, Yu; Hu, Xueyan
2016-03-01
Cooperative work of multiple magnetic transmitting sources is a new trend in the development of transient electromagnetic system. The key is the bipolar current waves shutdown, concurrently in the inductive load. In the past, it was difficult to use the constant clamping voltage technique to realize the synchronized shutdown of currents with different peak values. Based on clamping voltage technique, we introduce a new controlling method with constant shutdown time. We use the rising time to control shutdown time and use low voltage power source to control peak current. From the viewpoint of the circuit energy loss, by taking the high-voltage capacitor bypass resistance and the capacitor of the passive snubber circuit into account, we establish the relationship between the rising time and the shutdown time. Since the switch is not ideal, we propose a new method to test the shutdown time by the low voltage, the high voltage and the peak current. Experimental results show that adjustment of the current rising time can precisely control the value of the clamp voltage. When the rising time is fixed, the shutdown time is unchanged. The error for shutdown time deduced from the energy consumption is less than 6%. The new controlling method on current shutdown proposed in this paper can be used in the cooperative work of borehole and ground transmitting system.
Cosmological variation of the MOND constant: secular effects on galactic systems
Milgrom, Mordehai
2014-01-01
The proximity of the MOND acceleration constant with cosmological accelerations -- for example, a0~ cH0/2pi -- points to its possibly decreasing with cosmic time. I begin to consider the secular changes induced in galactic systems by such presumed variations, assumed adiabatic. It is important to understand these effects, in isolation from other evolutionary influences, in order to identify or constrain a0 variations by detection of induced effects, or lack thereof. I find that as long as the system is fully in the deep-MOND regime -- as applies to many galactic systems -- the adiabatic response of the system obeys simple scaling laws. For example, in a system that would be stationary for fixed a0, the system expands homologously as a0^{-1/4}, while internal velocities decrease uniformly as a0^{1/4}. If a0 is proportional to cH at all relevant times, this change amounts to a factor of ~ 2.5 since redshift 10. For a system stationary in a rotating frame, the angular frequency decreases as a0^{1/2}. The acceler...
Lewicki, G. W.; Guisinger, J. E. (Inventor)
1973-01-01
A system is developed for maintaining the intensity of a laser beam at a constant level in a thermomagnetic recording and magneto-optic playback system in which an isotropic film is heated along a continuous path by the laser beam for recording. As each successive area of the path is heated locally to the vicinity of its Curie point in the presence of a controlled magnetic field, a magneto-optic density is produced proportional to the amplitude of the controlled magnetic field. To play back the recorded signal, the intensity of the laser beam is reduced and a Faraday or Kerr effect analyzer is used, with a photodetector, as a transducer for producing an output signal.
Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede;
2016-01-01
strategies based on: 1) a power control (P-CPG), 2) a current limit method (I-CPG) and 3) the Perturb and Observe algorithm (P&O-CPG). However, the operational mode changes (e.g., from the maximum power point tracking to a CPG operation) will affect the entire system performance. Thus, a benchmarking of the......With a still increase of grid-connected Photovoltaic (PV) systems, challenges have been imposed on the grid due to the continuous injection of a large amount of fluctuating PV power, like overloading the grid infrastructure (e.g., transformers) during peak power production periods. Hence, advanced...... active power control methods are required. As a cost-effective solution to avoid overloading, a Constant Power Generation (CPG) control scheme by limiting the feed-in power has been introduced into the currently active grid regulations. In order to achieve a CPG operation, this paper proposes three CPG...
Quantum logic gates from time-dependent global magnetic field in a system with constant exchange
Nenashev, A. V., E-mail: nenashev@isp.nsc.ru; Dvurechenskii, A. V. [Rzhanov Institute of Semiconductor Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Zinovieva, A. F. [Rzhanov Institute of Semiconductor Physics SB RAS, 630090 Novosibirsk (Russian Federation); Gornov, A. Yu.; Zarodnyuk, T. S. [Institute for System Dynamics and Control Theory SB RAS, 664033 Irkutsk (Russian Federation)
2015-03-21
We propose a method that implements a universal set of one- and two-quantum-bit gates for quantum computation in a system of coupled electron pairs with constant non-diagonal exchange interaction. In our proposal, suppression of the exchange interaction is performed by the continual repetition of single-spin rotations. A small g-factor difference between the electrons allows for addressing qubits and avoiding strong magnetic field pulses. Numerical experiments were performed to show that, to implement the one- and two-qubit operations, it is sufficient to change the strength of the magnetic field by a few Gauss. This introduces one and then the other electron in a resonance. To determine the evolution of the two-qubit system, we use the algorithms of optimal control theory.
Super-Chandrasekhar dynamical friction in a constant-density spherical star system
Zelnikov, M. I.; Kuskov, D. S.
2016-02-01
N-body modelling of massive body motion in constant density-cores shows deviations in the dynamical friction force from Chandrasekhar's formula. When the body orbit falls within the core, the body experiences a stage of enhanced friction after which the friction force becomes very low or zero. This effect takes place for circular as well as radial and elliptic orbits of the massive perturber. Previously developed perturbative treatment of dynamical friction in spherical systems cannot be directly applied to constant density cores because of the importance of non-linear resonant effects in this case. This feature is caused by the full resonance of the moving body with all the stars in the harmonic potential. There has been a successful attempt at semi-analytical treatment of the problem, but there remains a lack of any analytical description of this phenomenon. We study the motion of a massive point-like object in a strictly constant density sphere analytically and obtain a formula for the energy decay rate of the object at the stage of super-Chandrasekhar friction. We show that the dynamical friction force at this stage is half an order in Mobject/Mcore stronger than in Chandrasekhar's case. Our numerical simulations for both circular and radial orbits of the perturber reveal the stage of enhanced friction and the stalling stage afterwards. Dependence of the decay time at the super-Chandrasekhar stage on the perturber mass confirms our analytical relationship. We compare our analytical formula with N-body results of other authors for the enhanced friction stage and find good agreement.
Hall normalization constants for the Bures volumes of the n-state quantum systems
Slater, Paul B.
1999-11-01
We report the results of certain integrations of quantum-theoretic interest, relying, in this regard, upon recently developed parametrizations of Boya et al (1998 Preprint quant-ph/9810084) of the n × n density matrices, in terms of squared components of the unit (n - 1)-sphere and the n × n unitary matrices. Firstly, we express the normalized volume elements of the Bures (minimal monotone) metric for n = 2 and 3, thereby obtaining `Bures prior probability distributions' over the two- and three-state systems. Then, as a first step in extending these results to n>3, we determine that the `Hall normalization constant' (Cn) for the marginal Bures prior probablity distribution over the (n - 1)-dimensional simplex of the n eigenvalues of the n × n density matrices is, for n = 4, equal to 71 680/icons/Journals/Common/pi" ALT="pi" ALIGN="TOP"/>2. Since we also find that C3 = 35/icons/Journals/Common/pi" ALT="pi" ALIGN="TOP"/>, it follows that C4 is simply equal to 211C3/icons/Journals/Common/pi" ALT="pi" ALIGN="TOP"/>. (C2 itself is known to equal 2/icons/Journals/Common/pi" ALT="pi" ALIGN="TOP"/>.) The constant C5 is also found. It too is associated with a remarkably simple decomposition, involving the product of the eight consecutive prime numbers from 3 to 23. We also preliminarily investigate several cases n>5, with the use of quasi-Monte Carlo integration. We hope that the various analyses reported will prove useful in deriving a general formula (which evidence suggests will involve the Bernoulli numbers) for the Hall normalization constant for arbitrary n. This would have diverse applications, including quantum inference and universal quantum coding.
Hall normalization constants for the Bures volumes of the n-state quantum systems
We report the results of certain integrations of quantum-theoretic interest, relying, in this regard, upon recently developed parametrizations of Boya et al (1998 Preprint quant-ph/9810084) of the nxn density matrices, in terms of squared components of the unit (n-1)-sphere and the nxn unitary matrices. Firstly, we express the normalized volume elements of the Bures (minimal monotone) metric for n=2 and 3, thereby obtaining 'Bures prior probability distributions' over the two- and three-state systems. Then, as a first step in extending these results to n>3, we determine that the 'Hall normalization constant' (Cn) for the marginal Bures prior probability distribution over the (n-1)-dimensional simplex of the n eigenvalues of the nxn density matrices is, for n=4, equal to 71 680/π2. Since we also find that C3=35/π, it follows that C4 is simply equal to 211C3/π. (C2 itself is known to equal 2/π.) The constant C5 is also found. It too is associated with a remarkably simple decomposition, involving the product of the eight consecutive prime numbers from 3 to 23. We also preliminarily investigate several cases n>5, with the use of quasi-Monte Carlo integration. We hope that the various analyses reported will prove useful in deriving a general formula (which evidence suggests will involve the Bernoulli numbers) for the Hall normalization constant for arbitrary n. This would have diverse applications, including quantum inference and universal quantum coding. (author)
Yong-gang PENG; Jun WANG; Wei WEI
2014-01-01
In view of the high energy consumption and low response speed of the traditional hydraulic system for an injection molding machine, a servo motor driven constant pump hydraulic system is designed for a precision injection molding process, which uses a servo motor, a constant pump, and a pressure sensor, instead of a common motor, a constant pump, a pressure pro-portion valve, and a flow proportion valve. A model predictive control strategy based on neurodynamic optimization is proposed to control this new hydraulic system in the injection molding process. Simulation results showed that this control method has good control precision and quick response.
Iacob, N.; Schinteie, G.; Bartha, C.; Palade, P.; Vekas, L.; Kuncser, V.
2016-07-01
A quantitative treatment of the effects of magnetic mutual interactions on the specific absorption rate of a superparamagnetic system of iron oxide nanoparticles coated with oleic acid is reported. The nanoparticle concentration of the considered ferrofluid samples varied from a very low (0.005) to a medium (0.16) value of the volume fraction, whereas the amplitude of the exciting AC magnetic field ranged from 14–35 kA m‑1. It was proved that a direct effect of the interparticle interactions resides in the regime of the modified superparamagnetism, dealing, besides the usual increase in the anisotropy energy barrier per nanoparticle, with the decrease in the specific time constant {τ0} of the relaxation law, usually considered as a material constant. Consequently, the increase in the specific absorption rate versus the volume fraction is significantly diminished in the presence of the interparticle interactions compared to the case of non-interacting superparamagnetic nanoparticles, with direct influence on the magnetic hyperthermia efficiency.
This paper presents a new concept of a partial flow sampling system (PFSS), involving a two-stage diluter which operates on the principle of underpressure, while exhaust is sampled through a capillary. Due to the low flowrate through the capillary, the diluter may be sampling from a freely exhausting tailpipe and is not prone to pressure variations in the exhaust line. In addition, the PFSS operates at constant pressure conditions even upstream of diesel particle filters that increase the backpressure in the tailpipe. As a result, the PFSS offers a constant dilution ratio (DR) over any engine or vehicle operation condition. This study presents the diluter concept and a straightforward model developed to calculate the DR, depending on the dilution air flowrate and the diluter underpressure. The model is validated using CO2 as a trace gas, and very good agreement is demonstrated between the calculated and the measured DR values. Following validation, the PFSS is combined with aerosol measurement instruments to measure the exhaust particle concentration of a diesel engine operating at different steady-state modes. For demonstrating the stability of the DR and applicability of the PFSS, measurements are conducted with both heavy duty and light duty diesel exhaust gases. Future applications of this device include gas and particle exhaust measurements both in laboratory environments and on-board vehicles. (paper)
ACTIVITIES OF THE ORGANIZATION ON PROVISION OF CONSTANT IMPROVEMENTS IN THE QUALITY SYSTEM
Sabahudin Jašarević
2010-03-01
Full Text Available Many authors agree in the statement that acquiring of certificate for introduced quality system is easier phase than from the phases which will follow. After acquiring of certificate the organizations have relaxation time and somewhere the time of easy dream. And when we wake up, control audits come fast and it is time to show to auditors what we have done in past period. So, maintenance and continuity in development of the quality system present next phases which many auditors estimate as more significant ones and more difficult from the phase of introduction of the quality system itself. By the appearance of standards from years of 2000 (ISO 9001:2000 and 2008 the concept of "continuous improvements" has been introduced in the practice of certification and maintenance of the quality system. Without such improvements and without work on them the quality system as well as all other things in real life would very soon come to the phase of collapse, i.e. quality characteristic s would start falling on all levels. This work will present results of researches conducted in 204 organizations with introduced quality sy stem as well as their activities carried out or to be carried out in the purpose of provision of constant improvements in their organizations. The work will also present comparison of different views seen by persons responsible for quality (manager for quality in organization as well as by managers of organization (directors.
Symplectic reduction of holonomic open-chain multi-body systems with constant momentum
Chhabra, Robin; Emami, M. Reza
2015-03-01
This paper presents a two-step symplectic geometric approach to the reduction of Hamilton's equation for open-chain, multi-body systems with multi-degree-of-freedom holonomic joints and constant momentum. First, symplectic reduction theorem is revisited for Hamiltonian systems on cotangent bundles. Then, we recall the notion of displacement subgroups, which is the class of multi-degree-of-freedom joints considered in this paper. We briefly study the kinematics of open-chain multi-body systems consisting of such joints. And, we show that the relative configuration manifold corresponding to the first joint is indeed a symmetry group for an open-chain multi-body system with multi-degree-of-freedom holonomic joints. Subsequently using symplectic reduction theorem at a non-zero momentum, we express Hamilton's equation of such a system in the symplectic reduced manifold, which is identified by the cotangent bundle of a quotient manifold. The kinetic energy metric of multi-body systems is further studied, and some sufficient conditions are introduced, under which the kinetic energy metric is invariant under the action of a subgroup of the configuration manifold. As a result, the symplectic reduction procedure for open-chain, multi-body systems is extended to a two-step reduction process for the dynamical equations of such systems. Finally, we explicitly derive the reduced dynamical equations in the local coordinates for an example of a six-degree-of-freedom manipulator mounted on a spacecraft, to demonstrate the results of this paper.
Table 5.1. Exchange current densities and rate constants in aqueous systems
Holze, R.
This document is part of Volume 9 `Electrochemistry', Subvolume A, of Landolt-Börnstein - Group IV `Physical Chemistry'. This document lists the exchange current densities and the electrode reaction rate constants of the following metallic electrodes in aqueous systems for various electrolyte reactions: silver (Ag), aluminium (Al), gold (Au), bismuth (Bi), carbon (C), cadmium (Cd), cobalt (Co), chromium (Cr), cesium (Cs), copper (Cu), iron (Fe), gallium (Ga), mercury (Hg), indium (In), iridium (Ir), potassium (K), lithium (Li), molybdenum (Mo), natrium (Na), niobium (Nb), nickel (Ni), lead (Pb), palladium (Pd), platinum (Pt), rubidium (Rb), rhodium (Rh), ruthenium (Ru), antimony (Sb), tin (Sn), tantalum (Ta), titanium (Ti), thallium (Tl), vanadium (V), tungsten (W), zinc (Zn). For each electrolyte reaction the electrolyte solution, the educt, product and concentration are specified along with the temperature of determination of the given values.
Constant-Power Engines in Flights to L4 point of the Earth-Moon System
Mircea DUMITRACHE
2012-03-01
Full Text Available The transfer is studied in the context of the classical Circular Restricted Three-Body Problem. The initial state is on a geosinchronous orbit and the terminal state is the L4 triangular Lagrangian point. The use of controllable acceleration engine by minimization of a time integral of the squared engine acceleration, the optimization problem is separated into two sub-problems: dynamical and parametric ones. Initial mass to constant output power ratio variation is mainly studied, depending on the transfer duration and initial thrust acceleration for fixed power jet (specific impulse is within the limits of the VASIMR magneto-plasma engine. The Two Point Boundary Value Problem is solved when the startup speed is circular or when the initial thrust acceleration is given. Time variation of the obtained state and control variables is represented relative to Earth in geocentric equatorial inertial system.
ADAPTIVE STEP-SIZE CONSTANT MODULUS ALGORITHM FOR BLIND MULTIUSER DETECTION IN DS-CDMA SYSTEMS
Sun Liping; Hu Guangrui
2004-01-01
Blind Adaptive Step-size Constant Modulus Algorithm (AS-CMA) for multiuser detection in DS-CDMA systems is presented. It combines the CMA and the concept of variable step-size, uses a second LMS algorithm for the step size. It adjusts the step-size according to the minimum output-energy principle within a specified range, thus overcomes the problems of bad effect of fixed step-size LMS algorithm. Compared with Adaptive Step-size LMS (AS-LMS) algorithm, through simulations, this algorithm can adapt the changes of the environment, suppress multiple access interference in the dynamic environment and the stability of Signal to Interference Ratio (SIR) is superior to that of AS-LMS.
A. Ibeas
2008-12-01
Full Text Available This paper investigates the asymptotic stability of switched linear time-varying systems with constant point delays under not very stringent conditions on the matrix functions of parameters. Such conditions are their boundedness, the existence of bounded time derivatives almost everywhere, and small amplitudes of the appearing Dirac impulses where such derivatives do not exist. It is also assumed that the system matrix for zero delay is stable with some prescribed stability abscissa for all time in order to obtain sufficiency-type conditions of asymptotic stability dependent on the delay sizes. Alternatively, it is assumed that the auxiliary system matrix defined for all the delayed system matrices being zero is stable with prescribed stability abscissa for all time to obtain results for global asymptotic stability independent of the delays. A particular subset of the switching instants is the so-called set of reset instants where switching leads to the parameterization to reset to a value within a prescribed set.
Modulo-p Addition Based Constant Weight Variable Length Prime Codes for SAC-OCDMA Systems
Malleswari.M
2014-01-01
Full Text Available In this paper, a novel prime code family called constant weight and variable length prime code (CWVLPC is presented. The CWVL prime code is constructed from the basic prime codes which are generated using modulo-p addition. Since the proposed code family possesses very good correlation property (cross correlation equal to zero, the system eliminates the phase induced intensity noise (PIIN and multi user interference (MUI completely. In addition, for any given prime number p, we can generate p number of code families with different length. Further, the weight of the proposed code is kept always equal to one independent of the prime number p and the p number of code families; thus it can simplify the design of encoder/decoder structures of the proposed SAC-OCDMA system. Also, bit error rate performance of the developed code is much better than the commonly used MQC code. To illustrate, for p=17 and an acceptable bit error rate of 10-9, the proposed coding system supports 225 simultaneous users with code length of 289 at an effective source power of -5 dBm.
GRUCAL: a program system for the calculation of macroscopic group constants
Nuclear reactor calculations require material- and composition-dependent, energy-averaged neutron physical data in order to decribe the interaction between neutrons and isotopes. The multigroup cross section code GRUCAL calculates these macroscopic group constants for given material compositions from the material-dependent data of the group constant library GRUBA. The instructions for calculating group constants are not fixed in the program, but are read in from an instruction file. This makes it possible to adapt GRUCAL to various problems or different group constant concepts
V.V. Kulish
2015-06-01
Full Text Available The paper investigates the antiferromagnetic vector distribution in an antiferromagnetic film with a system of antidots. A static distribution of the antiferromagnetic vector is written and a method – based on the minimization of the antiferromagnet energy – that allows reducing the number of boundary conditions required for finding the constants of this distribution is proposed. Equations for the distribution constants are obtained for the both cases of minimizing the antiferromagnet energy by one and by two distribution constants that enter the expression for the antiferromagnet energy. The method is illustrated on a system of one isolated antidot. For such system, one additional condition – for the case when two boundary conditions on the surface of the antidot are given – and two additional conditions – for the case when one boundary condition on the surface of the antidot is given – on the distribution constants are written.
The dissociation constants (pKa) and Gibb's free energies of 8-hydroxyquinoline have been determined in MeOH-water and EtOH-water solvents with percent variation from 10 to 50 % at the interval of 5 percent using UV-Spectrophotometer equipped with a temperature control accuracy of +- 0.1 degree centigrade. This compound gives two dissociation constants. The first basic thermodynamic dissociation constant pKa-t is 5.087 +- 0.011 at 20 degree centigrade which is not possible to be determine spectrophotometrically. The second thermodynamic dissociation constant pKa -t determined by spectrophotometrically varies from 9.853 +-0.010 to 9.310+-0.010 and 9.901+-0.011 to 9,413 +-0.010 in EtOH - water and MeOH - water solvent systems respectively at 25 degree centigrade. The related delta G's of thermodynamic dissociation constants very from -14.025 +- 0.013 to -12.610 +-0.014 kcal/mol for both solvents at 25 degree centigrade. The curve of pKa versus temperature is a distorted parabola. The ionization constant values decrease with increasing the temperature. The significance of relative magnitudes of the values is discussed and some useful generalization constants. A computer program in GW-BASIC has been used to calculate the /values of dissociation constants. From the pKa values Gibb's free energies are computed and discussed. (author)
Cold leg injection reflood test results in the SCTF Core-I under constant system pressure
The Slab Core Test Facility (SCTF) was constructed to investigate two-dimensional thermal-hydrodynamics in the core and the interaction in fluid behavior between the core and the upper plenum during the last part of blowdown, refill and reflood phases of a postulated loss-of-coolant accident (LOCA) of a pressurized water reactor (PWR). The present report describes the analytical results on the system behavior observed in the SCTF Core-I cold leg injection tests, S1-14 (Run 520), S1-15 (521), S1-16 (522), S1-17 (523), S1-20 (530), S1-21 (531), S1-23 (536) and S1-24 (537), performed under constant system pressure condition during transient. Major discussion items are: (1) steam binding, (2) U-tube oscillations, (3) bypass of ECC water (4) core cooling behavior, (5) effect of vent valve and (6) other parameter effects. These results give us very useful information and suggestion on reflood behavior. (author)
New upper limit on the cosmological constant from solar system dynamics
The cosmological constant Λ is the simplest model for explaining the dark energy which supposedly drives the observed accelerated expansion rate of the Universe. Together with the concept of cold dark matter, it satisfactorily accommodates a wealth of observations related to cosmology. Due to its assumed constancy throughout the Universe, Λ might also affect the dynamics of the planets in the solar system, although with extremely small effects. However, modern high-precision ephemerides provide a promising tool for constraining it. Using the supplementary advances in the perihelia provided by current INPOP10a and EPM2011 ephemerides, we obtain a new upper limit on Λ in the solar system when the Lense-Thirring effect due to the Sun's angular momentum and the uncertainty of the Sun's quadrupole moment are properly taken into account. These two factors were mostly absent in previous works dealing with Λ. We find that INPOP10a yields an upper limit of Λ = (0.26 ± 1.45) × 10−43 m−2 and EPM2011 gives Λ = (−0.44 ± 8.93) × 10−43 m−2. Such bounds are about 10 times less than previously estimated results
New self-excited variable speed constant frequency generator for wind power systems
Metwally, H.M.B. [Zagazig University (Egypt). Faculty of Engineering
2000-09-01
In this work, the possibility of using a new single-phase commutator machine as a stand-alone self-excited generator is investigated. The performance of this generator is tested under variable speed operation to simulate the practical case of variable wind turbine speed. The generator is self-excited through a resonance capacitor. The effect of varying the capacitance of this capacitor on the generated voltage and its frequency is studied. Load tests under a wide range of operating conditions are conducted to explore the capability of this type of generator. It has been found that this machine can operate as a variable speed constant frequency generator simply by varying the capacitance of the excitation capacitor. This important property makes this type of generator suitable for use in wind driven power systems. Finally, a mathematical model for the generator is obtained and a simulation program is developed to predict the performance of the generator. Close agreement between the simulation and the experimental results is obtained. (author)
Units Based on Constants: The Redefinition of the International System of Units
Stenger, J.; Ullrich, J. H.
2016-03-01
Recent decisions of the General Conference on Weights and Measures of the Metre Convention have opened the door to a fundamental change of the International System of Units, the SI, in 2018. The revised SI will be based on fixing the numerical values of seven defining constants corresponding to the seven traditional base units. This will bring about basic modifications in the definition of the kilogram, the ampere, the kelvin, and the mole and will have consequences for units derived from them. In contrast, the second, the meter, and the candela will not be affected. This paper describes the motivation and rationale behind this endeavor, introduces the new definitions, and reviews the requirements for the redefinitions as well as the status of the experiments that are currently being carried out to fulfill them. Benefits and a wide-reaching impact for the realization and dissemination of the units are anticipated because innovative technologies with ever-increasing accuracy will emerge, enabling the direct realization over widespread measurement ranges without the definitions themselves having to be changed.
American Society for Testing and Materials. Philadelphia
2008-01-01
1.1 This practice covers procedures for the dynamic verification of cyclic force amplitude control or measurement accuracy during constant amplitude testing in an axial fatigue testing system. It is based on the premise that force verification can be done with the use of a strain gaged elastic element. Use of this practice gives assurance that the accuracies of forces applied by the machine or dynamic force readings from the test machine, at the time of the test, after any user applied correction factors, fall within the limits recommended in Section 9. It does not address static accuracy which must first be addressed using Practices E 4 or equivalent. 1.2 Verification is specific to a particular test machine configuration and specimen. This standard is recommended to be used for each configuration of testing machine and specimen. Where dynamic correction factors are to be applied to test machine force readings in order to meet the accuracy recommended in Section 9, the verification is also specific to the c...
Bhatara, Sevty Satria; Iskandar, Reza Fauzi; Kirom, M. Ramdlan
2016-02-01
Solar energy is one of renewable energy resource where needs a photovoltaic module to convert it into electrical energy. One of the problems on solar energy conversion is the process of battery charging. To improve efficiency of energy conversion, PV system needs another control method on battery charging called maximum power point tracking (MPPT). This paper report the study on charging optimation using constant voltage (CV) method. This method has a function of determining output voltage of the PV system on maximal condition, so PV system will always produce a maximal energy. A model represented a PV system with and without MPPT was developed using Simulink. PV system simulation showed a different outcome energy when different solar radiation and numbers of solar module were applied in the model. On the simulation of solar radiation 1000 W/m2, PV system with MPPT produces 252.66 Watt energy and PV system without MPPT produces 252.66 Watt energy. The larger the solar radiation, the greater the energy of PV modules was produced.
Calculations on the hyperfine constants of the ground states for lithium-like system
Wu Xiao-Li; Yu Kai-Zhi; Gou Bing-Cong; Zhang Meng
2007-01-01
In this paper a relativistic many-body perturbation calculation is performed to calculate the hyperfine constants of the ground states for lithium-like isoelectronic sequence. Zeroth-order hyperfine constants are calculated with Dirac-Fock wavefunctions, and the finite basis sets of the Dirac-Fock equations are constructed by B splines. With the finite basis sets, the core polarization and the correlation effect are evaluated.
Current status of Russian Evaluated Neutron Data Libraries
The status of Russian Evaluated Data Libraries is discussed. The last modifications of the BROND-2 files and their relations to the additional files of the FOND library and the ABBN-90 group constants are considered. The main characteristics of new libraries for the photoneutron data, dosimetry and activation reaction cross sections and transmutation cross sections for intermediate energies are described briefly. (author)
This thesis looks into some qualitative properties, of dynamical systems occurring as ordinary differential equations. Essential information about the structure of the solution can be obtained without explicitly solving a linear system of differential equations with constant coefficients. This can be achieved by decomposing the operator of such a system into a semisimple and a nilpotent part. Fundamental theorems, concerning the existence of the solutions are discussed as well as the problem of stability of equilibrium points in dynamical systems (Liapunov's theorem). Gradient systems, special forms of dynamical systems, have particular properties that simplify the analysis of their flow. Finally, by applying the theory of dynamical systems to the Boltzmann equation with constant collision frequencies an investigation of equilibrium points is carried out. A mixture of three gases consisting of particles that interact through different collision mechanisms serves as the physical model. (Suda)
We propose a novel circuit to be applied to the front-end integrated circuits of gamma-ray spectroscopy systems. Our circuit is designed as a type of current conveyor (ICON) employing a constant-gm (transconductance) method which can significantly improve the linearity in the amplified signals by using a large time constant and the time-invariant characteristics of an amplifier. The constant-gm method is obtained by a feedback control which keeps the transconductance of the input transistor constant. To verify the performance of the propose circuit, the time constant variations for the channel resistances are simulated with the TSMC 0.18μm transistor parameters using HSPICE, and then compared with those of a conventional ICON. As a result, the proposed ICON shows only 0.02% output linearity variation and 0.19% time constant variation for the input amplitude up to 100 mV. These are significantly small values compared to a conventional ICON's 1.39% and 19.43%, respectively, for the same conditions.
The TENDL neutron data library and the TEND1038 38-group neutron constant system
The library contains neutron data for 103 nuclei - i.e. for 38 actinide nuclei (from 232Th to 249Cm), 26 fission fragment nuclei and 39 nuclei in structural and technological materials. The 38-group constants were obtained from TENDL. The high-energy group boundary is 20 MeV. The energy range below 1.2 eV contains 11 groups. Temperature and resonance effects were taken into account. The delayed neutron parameters for 6 groups and the yields of 40 fission fragments were obtained (light and heavy, stable and non-stable). The fast neutron features of spherical critical assemblies were calculated using constants from TEND1038. (author)
Kolowrocki, Krzysztof [Gdynia Maritime University, Gdynia (Poland)
2009-07-01
In the paper the multi-state approach to the analysis and evaluation of systems' reliability, risk and availability is practically applied. Theoretical definitions and results are illustrated by the example of their application in the reliability, risk and availability evaluation of an oil pipeline transportation system. The pipeline transportation system is considered in the constant in time operation conditions. The system reliability structure and its components reliability functions are not changing in constant operation conditions. The system reliability structure is fixed with a high accuracy. Whereas, the input reliability characteristics of the pipeline components are not sufficiently exact because of the lack of statistical data necessary for their estimation. The results may be considered as an illustration of the proposed methods possibilities of applications in pipeline systems reliability analysis. (author)
Sun, H. G.; Chen, W.; Wei, H.; Chen, Y. Q.
2011-03-01
How to characterize the memory property of systems is a challenging issue in the modeling and analysis of complex systems. This study makes a comparative investigation of integer-order derivative, constant-order fractional derivative and two types of variable-order fractional derivatives in characterizing the memory property of systems. The advantages and potential applications of two variable-order derivative definitions are highlighted through a comparative analysis of anomalous relaxation process.
Šesták, Jozef; Kahle, Vladislav
2014-01-01
Roč. 1350, Jul (2014), s. 68-71. ISSN 0021-9673 R&D Projects: GA MV VG20102015023 Institutional support: RVO:68081715 Keywords : constant pressure HPLC * gradient elution * simple liquid chromatograph Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.169, year: 2014 http://hdl.handle.net/11104/0233990
Dielectric constant and its role in the long range coherence in biological systems
Paul, R. (Calgary Univ., Alberta (Canada). Dept. of Chemistry); Chatterjee, R. (Calgary Univ., Alberta (Canada). Dept. of Physics)
1984-07-01
An expression for the dielectric constant has been derived for the Froehlich model of long-range coherence in biological cells. These theoretical expressions are employed to interpret the observed rouleaux formation of red blood cells (erythrocytes). It is concluded that this unusual behaviour of the erythrocytes can be interpreted satisfactorilly by the extended Froehlich model developed by us.
The dielectric constant and its role in the long range coherence in biological systems
An expression for the dielectric constant has been derived, for the Froehlich model of long-range coherence in biological cells. These theoretical expressions are employed to interpret the observed rouleaux formation of red blood cells (erythrocytes). It is concluded that this unusual behaviour of the erythrocytes can be interpreted satisfactorilly by the extended Froehlich model developed by us. (Author)
JIANG Xing-fang
2012-09-01
Full Text Available The Planck constant is an important constant inmodern physics. Its experimental verification isgenerally by the experiment of photoelectric effect.The data processing is very complex. In order tosimplify the complex question the intelligent system“Measuring of the Planck constant withphotoelectric effect” had been developed withmultimedia authoring tool Multimedia ToolBook. Theexperimental data was of large number that obtainedby user after the leakage current between electrodesand the anode current had been compensated. Whenthe data had been filled the corresponding fields, theintelligent system could display dynamically thevolt-ampere curve and the speed displayed could beadjusted. Especially when the user only completed the3 or 4 filters experiments and the number of the clampvoltages was 3 or 4, the intelligent experimental dataprocessing system could display the slope of the fittingstraight line and the Planck constant. In laboratory itprovided five filters. The intelligent system used thetechnologies such as the statistics method of “Nonzero plus one”, “the least square method”,“rounding off”, “The uncertainty had a bit and itwas aligned as the last bit of the significant figure”.After the arbitrarily 3 or 4 values of the clamp voltageor all 5 values of the clamp voltage had been filled inthe fields, the slope of the fitting straight line could becalculated and be drawn, and the Planck constant andits uncertainty could be calculated and be displayed.The fitting straight line was the relationship betweenthe clamp voltages and the incident light frequencies.The Planck constant was obtained by multiplying theslope of the fitting straight line with the electroniccharge. These methods could be applied to developvarious intelligent experimental data processingsystems
Barrow, J D
2005-01-01
We review properties of theories for the variation of the gravitation and fine structure 'constants'. We highlight some general features of the cosmological models that exist in these theories with reference to recent quasar data that are consistent with time-variation in the fine structure 'constant' since a redshift of 3.5. The behaviour of a simple class of varying-alpha cosmologies is outlined in the light of all the observational constraints.
Sergyeyev, Artur, E-mail: Artur.Sergyeyev@math.slu.cz [Mathematical Institute, Silesian University in Opava, Na Rybníčku 1, 746 01 Opava (Czech Republic)
2012-06-04
In the present Letter we extend the multiparameter coupling constant metamorphosis, also known as the generalized Stäckel transform, from Hamiltonian dynamical systems to general finite-dimensional dynamical systems and ODEs. This transform interchanges the values of integrals of motion with the parameters these integrals depend on but leaves the phase space coordinates intact. Sufficient conditions under which the transformation in question preserves integrability and a simple formula relating the solutions of the original system to those of the transformed one are given. -- Highlights: ► We consider the multiparameter coupling constant metamorphosis (MCCM). ► The latter is also known as the generalized Stäckel transform. ► This transform is extended to general (non-Hamiltonian) finite-dimensional dynamical systems. ► The extended transform preserves integrability just as the original MCCM. ► A simple formula for transforming solutions under MCCM is given.
In the present Letter we extend the multiparameter coupling constant metamorphosis, also known as the generalized Stäckel transform, from Hamiltonian dynamical systems to general finite-dimensional dynamical systems and ODEs. This transform interchanges the values of integrals of motion with the parameters these integrals depend on but leaves the phase space coordinates intact. Sufficient conditions under which the transformation in question preserves integrability and a simple formula relating the solutions of the original system to those of the transformed one are given. -- Highlights: ► We consider the multiparameter coupling constant metamorphosis (MCCM). ► The latter is also known as the generalized Stäckel transform. ► This transform is extended to general (non-Hamiltonian) finite-dimensional dynamical systems. ► The extended transform preserves integrability just as the original MCCM. ► A simple formula for transforming solutions under MCCM is given.
Stary, J
1979-01-01
Critical Evaluation of Equilibrium Constants Involving 8-Hydroxyquinoline and Its Metal Chelates presents and evaluates the published data on the solubility, dissociation, and liquid-liquid distribution of oxine and its metal chelates to recommend the most reliable numerical data. This book explores the dissociation constants of oxine in aqueous solutions.Organized into four chapters, this book begins with an overview of the characteristics of 8-hydroxyquinoline (oxine). This text then examines the total solubility of oxine in aqueous solution at different pH values. Other chapters consider th
Decay constants and mixing parameters in a relativistic model for q\\barQ system
Ahmady, M. R.; Mendel, R. R.; Talman, J.D.
1996-01-01
We extend our recent work, in which the Dirac equation with a ``(asymptotically free) Coulomb + (Lorentz scalar $\\gamma_0\\sigma r$) linear '' potential is used to obtain the light quark wavefunction for $q\\bar Q$ mesons in the limit $m_Q\\to \\infty$, to estimate the decay constant $f_P$ and the mixing parameter $B$ of the pseudoscalar mesons. We compare our results for the evolution of $f_P$ and $B$ with the meson mass $M_P$ to the non-relativistic formulas for these quantities and show that t...
Sakamoto, Sadaaki; Adachi, Hiroshige; Kaneko, Kazuhiro; Sugimoto, Yasutaka; Takada, Takahiro
2013-09-01
We found that the co-firing low temperature co-fired ceramic (LTCC) materials of different dielectric constants (ɛr) with Cu wiring is achievable using a novel, original design. It was confirmed that the dielectric characteristics of the dielectrics designed in this study are very suitable for the use of the dielectrics in electronic components such as filters mounted in high-speed radio communication equipment. The dielectric constants of the lower- and higher-dielectric-coefficient materials were 8.1 and 44.5, respectively, which are sufficiently effective for downsizing LTCC components. Observing the co-fired interface, it was confirmed that excellent co-firing conditions resulted in no mechanical defects such as delamination or cracks. On the basis of the results of wavelength dispersive X-ray spectrometry (WDX) and X-ray diffractometry (XRD), it was confirmed that co-firing with minimal interdiffusion was realized using the same glass for both dielectrics. It is concluded that the materials developed are good for co-firing in terms of the mechanical defects and interdiffusion that appear in them.
From extraction experiments and ?-activity measurements, the exchange extraction constants corresponding to the general equilibrium M2+(aq) + Sr2+(nb) ↔ M2+(nb) + Sr2+(aq) taking part in the two-phase water-nitrobenzene system (M2+ = Mg2+, Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Fe2+, Co2+, Ni2+; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the individual extraction constants of the M2+ cations in the mentioned two-phase system were calculated; they were found to increase in the following cation order: UO22+ 2+, Ni2+ 2+, Cd2+ 2+ 2+ 2+ 2+, Fe2+ 2+ 2+ 2+. (author)
From extraction experiments and ?-activity measurements, the exchange extraction constants corresponding to the general equilibrium M2+ (aq) + Sr2+ (org) ↔ M2+ (org) + Sr2+ (aq) taking place in the two-phase water-phenyltrifluoromethyl sulfone (abbrev. FS 13) system (M2+ Mg2+, Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Fe2+, Co2+, Ni2+; aq = aqueous phase, org = FS 13 phase) were evaluated. Furthermore, the individual extraction constants of the M2+ cations in this two-phase system were calculated; they were found to increase in the series of Mg2+, UO22+ 2+, Co2+ 2+, Ni2+ 2+ 2+, Mn2+, Fe2+ 2+ 2+. (author)
Lithium-ion Battery Charging System using Constant-Current Method with Fuzzy Logic Based ATmega16
Rossi Passarella; Ahmad Fali Oklilas; Tarida Mathilda
2014-01-01
In this charging system, constant-current charging technique keeps the current flow into the battery on its maximum range of 2A. The use of fuzzy logic control of this charging system is to control the value of PWM. PWM is controlling the value of current flowing to the battery during the charging process. The current value into the battery depends on the value of battery voltage and also its temperature. The cutoff system will occur if the temperature of the battery reaches its maximum range
Lithium-ion Battery Charging System using Constant-Current Method with Fuzzy Logic Based ATmega16
Rossi Passarella
2014-10-01
Full Text Available In this charging system, constant-current charging technique keeps the current flow into the battery on its maximum range of 2A. The use of fuzzy logic control of this charging system is to control the value of PWM. PWM is controlling the value of current flowing to the battery during the charging process. The current value into the battery depends on the value of battery voltage and also its temperature. The cutoff system will occur if the temperature of the battery reaches its maximum range
Sergyeyev, A
2010-01-01
In the present paper we extend the coupling constant metamorphosis, also known as the (multiparameter generalized) St\\"ackel transform, originally introduced for Hamiltonian dynamical systems, to general finite-dimensional dynamical systems and ODEs. Roughly speaking, the transformation in question interchanges the values of integrals of motion with the parameters that these integrals contain but leaves the phase space coordinates intact. Sufficient conditions under which the said transformation preserves integrability and a simple formula relating the solutions of the original system to those of the transformed one are given.
Mortensen, Dorthe Kragsig; Nielsen, Toke Rammer; Topp, Claus
The aim of this paper was to compare the indoor climate and the energy performance of a Constant Air Volume (CAV) system of 0.5h-1 with a Demand Controlled Ventilation (DCV) system controlled by occupancy and relative humidity for a studio apartment. Furthermore the impact of building materials...... hygroscopic properties on indoor climate and energy consumption was investigated for the two systems. Dynamic simulations of the studio apartment were carried out in the program WUFI+ with weather data from Copenhagen including outside temperature end relative humidity. For the non-hygroscopic case it was...
Tazhibayeva, Irina, E-mail: tazhibayeva@ntsc.kz [Institute of Atomic Energy NNC RK, Kurchatov (Kazakhstan); Kulsartov, Timur; Gordienko, Yuri [Institute of Atomic Energy NNC RK, Kurchatov (Kazakhstan); Mukanova, Aliya [Al’ Farabi Kazakh National University, Almaty (Kazakhstan); Ponkratov, Yuri; Barsukov, Nikolay; Tulubaev, Evgeniy [Institute of Atomic Energy NNC RK, Kurchatov (Kazakhstan); Platacis, Erik [University of Latvia (IPUL), Riga (Latvia); Kenzhin, Ergazy [Shakarim Semey State University, Semey (Kazakhstan)
2013-10-15
Highlights: • The experiments with Li CPS sample were carried out at reactor IVG-1.M. • The gas absorption technique was used to study hydrogen isotope interaction with lithium CPS. • The temperature dependence of constants of interaction rate was obtained for various power rates of the reactor. • Determination of the activation energies, and pre-exponents of Arrhenius dependence. • The effect of increase of the rate constant under reaction irradiation. -- Abstract: Experiments with a sample of a lithium capillary-porous system (CPS) were performed at the reactor IVG-1.M of the Institute of Atomic Energy NNC RK to study the effects of neutron irradiation on the parameters of hydrogen isotope interactions with a lithium CPS. The absorption technique was used during the experiments, and this technique allowed the temperature dependences of the hydrogen isotope interaction rate constants with the lithium CPS to be obtained under various reactor powers. The obtained dependencies were used to determine the main interaction parameters: the activation energies and the pre-exponents of the Arrhenius dependence of the hydrogen interaction rate constants with lithium and the lithium CPS. An increase of the hydrogen isotope interaction rate with the lithium CPS was observed under reactor irradiation.
Determination of the Rubidium Decay Constant by Age Comparison Against the U-Pb System
Nebel, O.; Mezger, K.; Scherer, E. E.; Davies, G. R.
2006-12-01
The currently accepted Rb decay constant (λ 87Rb) was suggested by the Subcommission on Geochronology [1] is 1.42 x 10-11yr-1, and has a potential precision at the percent level at best [2]. This value has been used in most Rb-Sr studies in the last three decades. Several attempts to refine λ87Rb by different techniques yielded results that, despite excellent reported precisions, differed from the proposed value and also from each other. In a recent evaluation of published calibrations of the decay constant, Begemann et al. [2] suggested a lower value [~ 1.40 x 10-11yr-1] but also called for a re-determination of λ87Rb to check its accuracy and significantly improve the precision. Subsequent re-determinations [3,4] yielded values that differ significantly from each other and from that proposed by the Subcommission on Geochronology [1], one of which being higher [3], the other one lower [4] than the recommended value. Therefore, at present, there is no consensus on the λ87Rb to be used in Rb-Sr chronology. Here we report three individual determinations of λ87Rb by the method of age comparison. This entails solving for λ87Rb using 1) the measured slopes of high precision Rb-Sr isochrons from igneous rocks and minerals and 2) the emplacement ages of these samples as determined by the precise and presumably accurate U-Pb method. The precision of the measured 87Rb/86Sr has been improved to ~0.2% by measuring Rb concentrations by isotope dilution MC-ICPMS [5] (cf. ~1% for TIMS data). A challenging aspect of Rb-Sr studies is that of spike calibration, which is generally performed using standards prepared from salts of Rb and Sr rather than pure metals. The Rb/Sr values of individual spikes calibrated against two standard solutions made from different salts (iodide and carbonate) agree to within 0.15%, strongly suggesting that the stoichiometry of the salts, after careful dehydration, is sufficiently ideal for accurate spike calibrations. The calibration was checked
Emerging the dark sector from thermodynamics of cosmological systems with constant pressure
Aviles, Alejandro; Klapp, Jaime; Luongo, Orlando
2014-01-01
We investigate the thermodynamics of general fluids that have the constriction that their pressure is constant. For example, this happens in the case of pure dust matter, for which the pressure vanishes and also in the case of standard dark matter phenomenology. Assuming a finite non-zero pressure, the corresponding dynamics is richer than one naively would expect. In particular, it can be considered as a unified description of dark energy and dark matter. We first consider the more general thermodynamic properties of this class of fluids finding the important result that for them adiabatic and isothermal processes should coincide. We therefore study their behaviors in curved space-times where local thermal equilibrium can be appealed. Thus, we show that this dark fluid degenerates with the dark sector of the LCDM model only in the case of adiabatic evolution. We demonstrate that, adding dissipative processes, a phantom behavior can occur and finally we further highlight that an arbitrary decomposition of the...
De Martino, S; Illuminati, F; Martino, Salvatore De; Siena, Silvio De; Illuminati, Fabrizio
1999-01-01
The possibility is discussed of inferring or simulating some aspects of quantum dynamics by adding classical statistical fluctuations to classical mechanics. We introduce a general principle of mechanical stability and derive a necessary condition for classical chaotic fluctuations to affect confined dynamical systems, on any scale, ranging from microscopic to macroscopic domains. As a consequence we obtain, both for microscopic and macroscopic aggregates, dimensional relations defining the minimum unit of action of individual constituents, yielding in all cases Planck action constant.
Johnston, Bryan
2013-01-01
We demonstrate that the fraction of sales lost for the (r, q) system under consideration can be conveniently bounded in a manner suitable for quick, back-of-the-envelope estimates. We assume that customer demand arises from a Poisson process with one unit demanded at a time, that all demand occurring during a stockout is lost, and that lead time is constant. In addition, we allow the situation where multiple replenishment orders may be simultaneously outstanding. We show that the difference b...
The Cauchy problem for the system of linear pseudodifferential equations is considered. For two classes of such systems including partial differential systems with conbstant and rapidity decreasing variable coefficients a solution by series is obtained. The series is represented in the form of feynman integral in phase space of chronological exponent of operator-valued symbol of pseudodifferential operator
Sparavigna, Amelia Carolina
2012-01-01
As proposed in a previous paper, the decorations of ancient objects can provide some information on the approximate evaluations of constant {\\pi}, the ratio of circumference to diameter. Here we discuss some disks found in the tomb of Hemaka, the chancellor of a king of the First Dynasty of Egypt, about 3000 BC. The discussion is based on measurements of the dimensionless ratio of lengths.
Robinson, H.P.; Potter, Elinor
1971-03-01
This collection of mathematical data consists of two tables of decimal constants arranged according to size rather than function, a third table of integers from 1 to 1000, giving some of their properties, and a fourth table listing some infinite series arranged according to increasing size of the coefficients of the terms. The decimal values of Tables I and II are given to 20 D.
Bracken, Paul; Grundland, Alfred M.
1999-01-01
Analysis of the generalized Weierstrass-Enneper system includes the estimation of the degree of indeterminancy of the general analytic solution and the discussion of the boundary value problem. Several different procedures for constructing certain classes of solutions to this system, including potential, harmonic and separable types of solutions, are proposed. A technique for reduction of the Weierstrass-Enneper system to decoupled linear equations, by subjecting it to certain differential co...
Realization of Constant-Current Mode for a Contactless Battery Charging System
Yue Sun; Zheng-You He; Yan-Ling Li; Xin Dai
2013-01-01
For a contactless battery charging system based on inductively coupled power transfer technology, a generalized state-space averaging method is first introduced, which can convert the original system with the oscillating and nonlinear characteristics to a linear time-invariant system by using the low-order Fourier series to approximate the original circuit signals and nonlinear terms and then the performance weighting functions for multi-objective optimization are adjusted and chosen in the f...
Highlights: ► New method to precisely measure TE module and semiconductor parameters is developed. ► The new method is realized with a computer controlled apparatus called TEPAS. ► Fifteen different TE modules are studied with TEPAS, their parameters are obtained. ► The theoretic and experimental results validate the accuracy of new method and TEPAS. - Abstract: Thermoelectric and dynamic parameters of thermoelectric (TE) modules such as time constant are of crucial importance in production and utilization of these modules. Many techniques, apparatuses and software have been developed to determine the performance related parameters and time constants of TE modules; however, these techniques based on the assumption that the parameters of the semiconductors are constant or have time dependency only. Hence, the performance analyses of TE modules with these methods lack accuracy. In this study, Z, K, R and τ parameters of standard TE modules of Melcor Inc. have been acquired with a new computer controlled test system, Thermoelectric Performance Analysis System (TEPAS) which includes hardware and software based on the new method, variables of which are easily measurable temperature, current and voltage. The parameters Z, K, R and τ attained are compared with direct measurement results and the advantage of the new method and TEPAS have been demonstrated. Time constants of 15 different thermoelectric modules are calculated with the new method and three of them are attained with TEPAS. The results are compared with the other theoretical calculations and measurements available in literature. The system’s control and interface software was developed by Delphi visual programming language.
Pulsing a 4.1 MW Motor Generator System to 34 MW Peak Power Under Constant Input Power Operation
Brookhaven operates a 9 MW motor generator, made by Siemens, as part of the main magnet power supply of the Alternating Gradient Synchrotron (AGS) accelerator. A cycloconverter power supply system is utilized to ensure that during pulsing the main magnets of the AGS up to 50 MW peak power, the input power of the motor generator remains constant. There is also another motor generator (MG set) at Brookhaven, a 40 year old system manufactured by Westinghouse. This MG set could be pulsed up to 34 MW peak power while the input average power should not exceed 4.1 MW. A project is underway to upgrade this MG system and it's controls, so it could be used as a spare while doing maintenance on the Siemens MG and thus not interrupting the RHIC physics program. The purpose of this paper is to show that it is possible to pulse the AGS magnets using the Westinghouse MG system without utilizing a cycloconverter power supply, and still be able to maintain the input power to the motor generator constant. Calculations will be provided to show that they can pulse the position of the liquid rheostat in the motor rotor circuit to support the above, while taking out the power necessary to pulse the AGS magnets. This solution is being implemented due to budget constraints and overall simplicity. The hydraulic system to accomplish this task will also be described
PULSING A 4.1 MW MOTOR GENERATOR SYSTEM TO 34 MW PEAK POWER UNDER CONSTANT INPUT POWER OPERATION.
MARNERIS,I.; BADEA,V.; BANNON,M.; BONATI,R.; DANOWAKI,G.; SANDBERG,J.; SOUKAS,A.
1999-03-29
Brookhaven operates a 9 MW motor generator, made by Siemens, as part of the main magnet power supply of the Alternating Gradient Synchrotron (AGS) accelerator. A cycloconverter power supply system is utilized to ensure that during pulsing the main magnets of the AGS up to 50 MW peak power, the input power of the motor generator remains constant. There is also another motor generator (MG set) at Brookhaven, a 40 year old system manufactured by Westinghouse. This MG set could be pulsed up to 34 MW peak power while the input average power should not exceed. 4.1 M&V. A project is underway to upgrade this MG system and it's controls, so it could be used as a spare while doing maintenance on the Siemens MG and thus not interrupting the RHIC physics program. The purpose of this paper is to show that it is possible to pulse the AGS magnets using the Westinghouse MG system without utilizing a cycloconverter power supply, and still be able to maintain the input power to the motor generator constant. Calculations will be provided to show that we can pulse the position of the liquid rheostat in the motor rotor circuit to support the above, while taking out the power necessary to pulse the AGS magnets. This solution is being implemented due to budget constraints and overall simplicity. The hydraulic system to accomplish this task will also be described.
Optical timing receiver for the NASA laser ranging system. Part I. Constant-fraction discriminator
Position-resolution capabilities of the NASA laser ranging system are essentially determined by time-resolution capabilities of its optical timing receiver. The optical timing receiver consists of a fast photoelectric device, primarily a standard of microchannel-plate-type photomultiplier or an avalanche photodiode detector, a timing discriminator, a high-precision time-interval digitizer, and a signal-processing system. The time-resolution capabilities of the receiver are determined by the photoelectron time spread of the photoelectric device, the time walk and resolution characteristics of the timing discriminator, and the time-interval digitizer. It is thus necessary to evaluate available fast photoelectronic devices with respect to their time-resolution capabilities, and to design a very low time walk timing discriminator and a high-precision time digitizer which will be used in the laser ranging system receiver. (auth)
Systemizing: A Cross-Cultural Constant for Motivation to Learn Science
Zeyer, Albert; Çetin-Dindar, Ayla; Md Zain, Ahmad Nurulazam; Juriševic, Mojca; Devetak, Iztok; Odermatt, Freia
2013-01-01
The present study is based on the empathizing-systemizing (E-S) theory of cognitive science. It was hypothesized that the influence of students' gender on their motivation to learn science is often overestimated in the research literature and that cognitive style is more important for motivation than students' gender. By using structural…
Di Francesco, Marco
2011-04-01
The dependence of tumor on essential nutrients is known to be crucial for its evolution and has become one of the targets for medical therapies. Based on this fact a reaction-diffusion system with chemotaxis term and nutrient-based growth of tumors is presented. The formulation of the model considers also an influence of tumor and pharmacological factors on nutrient concentration. In the paper, convergence of solutions to constant, stationary states in the one-dimensional case for small perturbation of the equilibria is investigated. The nonlinear stability results are obtained by means of the classical symmetrization method and energy Sobolev estimates. © 2010 Elsevier Ltd.
The program system FEDGROUP was originally released for general distribution in June 1976. It is widely applied for the generation of group constant libraries used by different spectral codes. In this revised version of report INDC/HUN/-13 errors, deficiencies and misprints in the original report have been removed and an extension is introduced and described. The basic computer of FEDGROUP is the CDC-3300. There exist, however, CYBER-72, BESM-6 and IBM-360 versions, too. The problems connected with the various computer versions are discussed. Results of test calculations are quoted and errata to the report INDC/HUN/-13 are given
Klioner, S A
2005-01-01
The paper is devoted to a detailed explanation of relativistic scaling of astronomical quantities induced by times scales \\TDB and \\TT. It is argued that scaled time scales, scaled spatial coordinates and scaled masses should be considered as distinct quantities which themselves can be expressed in any units (rather then numerical values expressed in some non-SI units ("TDB units" and "TT units") as can be sometimes found in the literature). The system of astronomical units in the relativistic framework is discussed. The whole freedom in the definitions of the systems of astronomical units for TCB and TDB is demonstrated. A number of possible ways to freeze the freedom are shown and discussed. It is argued that in the near future one should probably think about converting AU into a defined quantity (by fixing its value in SI meters).
On the Formulation of Flexible Multibody Systems with Constant Mass Matrix
Pedersen, Niels Leergaard
1997-01-01
A flexible body in a multibody system isdescribed only by the position of the nodes in theinertial frame. With this description we can formulatethe mass matrix of the flexible multibody as aconstant matrix. This matrix can be inverted in apreprocessing stage which yields a more efficientaccelerat...... this formulation is that neither thecentrifugal nor the Coriolis forces appear in theequations due to the description of the flexible body....
The structure of the SADKO-2 program system, providing for calculations of radiation transport by the group methods for protons, π-mesons within the energy range from 20 MeV to 10 TeV; for neutrons-from the thermal one to 10 TeV; for photons-from 0.01 up to 15 MeV. The SADKO system containing the program for calculation of complete and twice-differential cross section of inelastic hA-interaction, the program for calculation of group microcross sections for particles with energy above 20 MeV and the program for calculation of group microcross sections for isotope mixtures. The file of the group cross sections in a predetermined format, prepared with an account of the components composition of the shielding and detector substance, constitute the result of the SADKO-2 constant system operation. 25 refs., 7 figs
Constant-coefficient FIR filters based on residue number system arithmetic
Stamenković Negovan
2012-01-01
Full Text Available In this paper, the design of a Finite Impulse Response (FIR filter based on the residue number system (RNS is presented. We chose to implement it in the (RNS, because the RNS offers high speed and low power dissipation. This architecture is based on the single RNS multiplier-accumulator (MAC unit. The three moduli set {2n+1,2n,2n-1}, which avoids 2n+1 modulus, is used to design FIR filter. A numerical example illustrates the principles of residue encoding, residue arithmetic, and residue decoding for FIR filters.
Constant force actuator for gravitational wave detector's seismic attenuation systems (SAS)
We have designed, tested and implemented a UHV-compatible, low-noise, non-contacting force actuator for DC positioning and inertial damping of the rigid body resonances of the Seismic Attenuation System (SAS) designed for the TAMA Gravitational Wave Interferometer. The actuator fully satisfies the stringent zero-force-gradient requirements that are necessary to prevent re-injecting seismic noise into the SAS chain. The actuator's closed magnetic field design makes for particularly low power requirements, and low susceptibility to external perturbations. The actuator retains enough strength to absorb seismic perturbations even during small earthquakes
In order to ensure long-term stability of beam parameters of linear accelerators is working on stabilizing the excitation of high-power systems. At this stage the solution of the problem, developed and applied in practice stabilization focusing coil current klystron KIU-37 to eliminate the dependence of the output power from the mains supply voltage fluctuations and other destabilizing factors. Its use has provided the stability of the output current in the range of +-0.5% with changes in the supply voltage +-10%, which, in turn, made it possible to significantly increase the long term stability of parameters of the excitation signal
This article presents the results of subjects identification, for following of creating base models in Simulink (included in Matlab5.3) of automatic control system, synchronous generator and motor. The method for timing rows analysis is used the received third line contains the machine's time constants: d axis transient short - circuit time constant Td' and consist of mechanical parameters, initial conditions and saturation parameters. The results of research allow creating models of type 'machine-regulator', for analysis in Simulink to Matlab identically by specification objects. (authors)
PIAO; Daxiong
2001-01-01
., Wampler, E. J., Gaskell, C. M., Emission-line properties of optically and radio-selected complete quasars samples, Astrophys. J., 1989, 338: 630.［13］Yong, P., Sargent, W. L. W. A., High-resolution study of the absorption spectra of three QSOs: evidence for cosmological evolution in the lyman-alpha lines, Astrophys. J., 1982, 252: 10.［14］Lawrence, J., Zucker, J. R., Readhead, A. C. S. et al., Optical spectra of a complete sample of radio sources I. The spectra, Astrophys. J. Suppl., 1996, 107: 541.［15］Junkkarinen, V. T. , Burbidge E. M. , Smith, H. E. , Spectrophyotometry of six broad absoption line QSOs, Astrophys. J. ,1987, 317, 460.［16］Laor, A., Babcall, J. N., Jannuzi, B. T. et al., The ultraviolet emission properties of 13 quasars, Astrophys. J. Suppl.,1995, 99: 1.［17］Baldwin, J. A., Rees, M. J., Longair, M. S. et al., QSOs with narrow emission lines, Astrophys. J., 1988, 327: 103.［18］Shaver, P. A. , Boksenberg A. , Robertson, J. G. , Spectroscopy of the QSO pair Q0028 + 003/Q0029 + 003, Astrophys.J., 1982, 261: L7.［19］Baldwin, J. A., Netzer, H., The emission-line regions of high-redshift QSOs, Astrophys. J., 1978, 226: 1.［20］Wills, B. J., Thompson, K. L., Han, M. et al. , The Hubble space telescope sample of radio-loud quasars: Ultraviolet spectra of the first 31 quasars, Astrophys. J., 1995, 447: 139.［21］Osmer, P. S., Smith, M. G. , Discovery and spectroscopic observations of 27 optical selected quasars with 1.4 ＜ z ＜ 2.5,Astrophys. J., 1977, 213: 607.［22］Storrie-Lombardi, L. J., McMabon, R. G., Irwin, M. J. et al., APM Z ＞ = 4 QSO Survey: Spectra and Intervening Ab-sorption Systems, Astrophys. J., 1996, 468: 121.［23］Young, P. , Sargent, W. L. W. , Boksenberg, A. , Clv absorption in an unbiased sample of 33 QSOs: evidence for the inter-vening galaxy hypothesis, Astrophys. J. Suppl., 1982, 48: 455.［24］Zitelli, V., Mignoli, M., Zarano, B. et al., A spectroscopically complete sample of quasars with Bj ≤ 22
A device for measuring the exposure rate from neutron-activated indium foil, under constant geometry, has been designed, constructed, and tested. The device is intended for use with the Juno ionization chambers, although it adapts to Victoreen CDV-700 and Victoreen 193 G-M instruments. Juno dose-response data for low (53 rad) and high (226 rad) doses were compiled and modeled. This model was compared to that assumed from the indium foil dose-response model in current use; plots of fitted and assumed models are congruent. An analysis of data from both Juno and CDV-700 instruments indicates that the constant geometry device may be used effectively to monitor the decay of In-116m. Tolerance limits for the Juno dose-response curve increase with time after activation, which results in diminished precision of dose estimates made by indium foil measurement. From the data collected in these experiments, the system appears to be most useful if activation is measured within 250 min after exposure. 5 references, 7 figures, 1 table
Jeon, Su-Jin; Park, Chang-In; Son, Byung-Hee; Jung, Mi; Jang, Teak-Jin; Lee, Chun-Sik; Choi, Young-Wan
2016-03-01
Position-sensitive photomultiplier tubes (PSPMTs) in array are used as gamma ray position detector. Each PMT converts the light of wide spectrum range (100 nm ~ 2500 nm) to electrical signal with amplification. Because detection system size is determined by the number of output channels in the PSPMTs, resistive network has been used for reducing the number of output channels. The photo-generated current is distributed to the four output current pulses according to a ratio by resistance values of resistive network. The detected positions are estimated by the peak value of the distributed current pulses. However, due to parasitic capacitance of PSPMTs in parallel with resistor in the resistive network, the time constants should be considered. When the duration of current pulse is not long enough, peak value of distributed pulses is reduced and detected position error is increased. In this paper, we analyzed the detected position error in the resistive network and variation of time constant according to the input position of the PSPMTs.
Graphical abstract: The work aimed at studying the performance of a steam jet refrigeration system with (i) a constant area ejector and (ii) a variable area ejector under different operating conditions both experimentally and computationally. The boiler temperature was varied from 90 °C to 120 °C, the evaporator temperature was varied from 5 °C to 15 °C and the entertainment ratio, variation of Mach number along the ejector and the Coefficient of Performance were obtained. With proper design, the shock phenomenon in the variable area ejector was eliminated as shown in the left figure, which resulted in a better performance of the variable area ejector over a range of evaporator temperatures. The study also confirmed that the system can operate steadily at a boiler temperature of 90 °C which can be obtained from waste heat. - Highlights: • Experimental and computational studies on steam jet refrigeration system carried out. • Constant area and variable area ejectors were designed for low heat input. • Evaporator temperature was varied from 5 °C to 15 °C and the boiler temperature from 90 °C to 120 °C. • At the lower boiler temperature, no shock formed in the variable area ejector resulting in better performance. • A steam jet refrigeration system can operate steadily at boiler temperature of 90 °C. - Abstract: This paper first presents the results from an experimental study of a conventional steam jet ejector refrigeration system and compares the performance with the computational fluid dynamics (CFD) results of the same. Secondly, it describes a method of developing a variable area supersonic ejector and presents experimental results of the operating performance of the variable area ejector over the same operating conditions. The two ejectors were experimentally tested for boiler temperatures below 120 °C and an evaporator temperature below 15 °C. It was found that the steam jet refrigeration system can operate with stability at low boiler
Rossi-Alpha measurements were performed on uranium diluted with matrix material systems to determine the prompt neutron decay constants. These constants represent an eigenvalue characteristic of these particular critical assemblies, which can be experimentally measured by the Rossi-Alpha or pulse neutron source techniques and calculated by a deterministic or Monte Carlo method. In the measurements presented in this paper, highly enriched foils diluted in various X/235U ratios with polyethylene and SiO2, and polyethylene and aluminum were assembled to a high multiplication, and the prompt neutron decay constants were obtained by the Rossi-Alpha technique. The uranium diluted with matrix material experiments were fueled with highly enriched uranium foils. The average dimensions of the bare foils were 22.86 cm squared and 0.00762 cm thick. The foils were laminated with plastic sheets to reduce the amount of airborne contamination. Each foil weighed ∼70 g. The diluent material consisted of SiO2, or 6061 aluminum plates, which were embedded into polyethylene plates. The SiO2 and aluminum plates were 22.86 cm square and 0.64 cm thick. The polyethylene plates were 39.12 cm square and 1.91 cm thick. Each polyethylene plate had a central recess whose dimensions were 22.86 cm by 22.86 cm by 0.64 cm deep and was used to accommodate the SiO2, or aluminum plates as well as the uranium foils. There were eight 39.12-cm-squared by 2.54-cm-thick high density polyethylene plates that form the top and bottom reflectors (four at the top and four at the bottom). Also, one of the polyethylene plates located in the center of the assembly had holes drilled in a radial direction to accommodate neutron detectors. Four 3He detectors were placed in this plate. The 3He detectors were 1.27 cm in diameter and ∼15 cm long. Rossi-Alpha measurements were performed at several subcritical separations for both experiments. The data were collected with a type I time analyzer (PATRM). This time
Cosmological Constant, Fine Structure Constant and Beyond
Wei, Hao; Li, Hong-Yu; Xue, Dong-Ze
2016-01-01
In this work, we consider the cosmological constant model $\\Lambda\\propto\\alpha^{-6}$, which is well motivated from three independent approaches. As is well known, the evidence of varying fine structure constant $\\alpha$ was found in 1998. If $\\Lambda\\propto\\alpha^{-6}$ is right, it means that the cosmological constant $\\Lambda$ should be also varying. In this work, we try to develop a suitable framework to model this varying cosmological constant $\\Lambda\\propto\\alpha^{-6}$, in which we view it from an interacting vacuum energy perspective. We propose two types of models to describe the evolutions of $\\Lambda$ and $\\alpha$. Then, we consider the observational constraints on these models, by using the 293 $\\Delta\\alpha/\\alpha$ data from the absorption systems in the spectra of distant quasars, and the data of type Ia supernovae (SNIa), cosmic microwave background (CMB), baryon acoustic oscillation (BAO). We find that the model parameters can be tightly constrained to the narrow ranges of ${\\cal O}(10^{-5})$ t...
The ferromagnetic resonance intrinsic field linewidth ΔH is investigated for a multilayer system such as a coupled trilayer and a spin valve structure. The magnetic coupling between two ferromagnetic layers separated by a nonmagnetic interlayer will be described by the bilinear J1 and biquadratic J2 coupling parameters. The interaction at the interface of the first ferromagnetic layer with the antiferromagnetic one is account for by the exchange anisotropy field, HE. A general formula is derived for the intrinsic linewidth ΔH. The explicit dependence of ΔH with HE, J1 and J2 will be highlighted. Analytical expressions for each mode field linewidth are found in special cases. Equivalent damping constants will be discussed
常国宾; 柳明
2015-01-01
In inertial navigation system (INS) and global positioning system (GPS) integrated system, GPS antennas are usually not located at the same location as the inertial measurement unit (IMU) of the INS, so the lever arm effect exists, which makes the observation equation highly nonlinear. The INS/GPS integration with constant lever arm effect is studied. The position relation of IMU and GPS’s antenna is represented in the earth centered earth fixed frame, while the velocity relation of these two systems is represented in local horizontal frame. Due to the small integration time interval of INS, i.e. 0.1 s in this work, the nonlinearity in the INS error equation is trivial, so the linear INS error model is constructed and addressed by Kalman filter’s prediction step. On the other hand, the high nonlinearity in the observation equation due to lever arm effect is addressed by unscented Kalman filter’s update step to attain higher accuracy and better applicability. Simulation is designed and the performance of the hybrid filter is validated.
金文敬
2011-01-01
The situation of astronomical constant system adopted by the IAU since 1900 has been briefly reviewed. The mathematical relation between some astronomical constants and the main reason for the change of astronomical constant system each time in the past are described. Especially, the work on the IAU astronomical constant system, including the establishment of working groups and adoption of the current best estimates since 1991, is introduced. The background of the IAU 2009 astronomical constant system instead of the IAU 1976 astronomical constant system is given. As for this change the reasons are the appearance of new measurements of astronomical constants with exploration of the Solar system, application of the Barycentric Celestial Reference System and Geocentric Celestial Reference System under the relativistic reference frame after 1991 and the adoption of new models for precession and nutation after 2006. The comparison between the IAU 2009 and 1976 astronomical constant system is given. Finally, the work on astronomical constants in China, such as determination of precession constant from proper motion, the definition of astronomical unit under the relativistic reference frame, determination of nutation constant from globe optical classical observations during 1962.0-1982.0, Corrections to the IAU 1976 precession constant and the coefficients of the IAU nutation series from VLBI data by using various networks during April 1980-December 1995, establishment of a new nutation model of a non-rigid earth with ocean and atmosphere etc. is briefly mentioned. Some suggestions for the further work on astronomical constants are proposed as follows:(1) Shanghai Astronomical Observatory (SHAO) incorporates the international organizations of ILRS, IVS and IGS. The globe solution are given from processing the observational data of SLR、 GPS and VLBI routinely. By using these globe data not only the Earth Orientation Parameters, plate motion and regional crustal
Solaimani, M.; Morteza, Izadifard [Faculty of Physics, Shahrood University of technology, Shahrood (Iran, Islamic Republic of); Arabshahi, H., E-mail: arabshahi@um.ac.ir [Department of Physics, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Physics Department, Payame Noor University, P.O. Box 19395-3697, Tehran (Iran, Islamic Republic of); Reza, Sarkardehi Mohammad [Physics Department, Al-Zahra University, Vanak, Tehran (Iran, Islamic Republic of)
2013-02-15
In this work, we have studied the effect of the number of the wells, in a multiple quantum wells structure with constant total effective length, on the optical properties of multiple quantum wells like the absorption coefficient and the refractive index by means of compact density matrix approach. GaAs/Al{sub x}Ga{sub (1-x)}As multiple quantum wells systems was selected as an example. Besides, the effect of varying number of wells on the subband energies, wave functions, number of bound states, and the Fermi energy have been also investigated. Our calculation revealed that the number of wells in a multiple quantum well is a criterion with which we can control the amount of nonlinearity. This study showed that for the third order refractive index change there is two regimes of variations and the critical well number was six. In our calculations, we have used the same wells and barrier thicknesses to construct the multiple quantum wells system. - Highlights: Black-Right-Pointing-Pointer OptiOptical Non-Linear. Black-Right-Pointing-Pointer Total Effective Length. Black-Right-Pointing-Pointer Multiple Quantum Wells System - genetic algorithm Black-Right-Pointing-Pointer Schroedinger equation solution. Black-Right-Pointing-Pointer Nanostructure.
JIANG Xing-fang; LIYan-ji; Jiang, Hong
2012-01-01
The Planck constant is an important constant inmodern physics. Its experimental verification isgenerally by the experiment of photoelectric effect.The data processing is very complex. In order tosimplify the complex question the intelligent system“Measuring of the Planck constant withphotoelectric effect” had been developed withmultimedia authoring tool Multimedia ToolBook. Theexperimental data was of large number that obtainedby user after the leakage current between electrodesand the anode ...
Brokaw, R. S.; Brabbs, T. A.; Snyder, C. A.
1985-01-01
Exponential free radical growth constants have been measured for ethane carbon monoxide oxygen mixtures by monitoring the growth of oxygen atom concentration as manifested by CO flame band emission. Data were obtained over the temperature range of 1200 to 1700 K. The data were analyzed using an ethane oxidation mechanism involving seven elementary reaction steps. Calculated growth constants were close to experimental values at lower temperatures, up to about 1400 K, but at higher temperatures computed growth constants were considerably smaller than experiment. In attempts to explain these results additional branching reactions were added to the mechanism. However, these additional reactions did not appreciably change calculated growth constants.
Fenner, Y; Gibson, B K
2005-01-01
At redshifts z_abs < 2, quasar absorption-line constraints on space-time variations in the fine-structure constant, alpha, rely on the comparison of MgII and FeII transition wavelengths. One potentially important uncertainty is the relative abundance of Mg isotopes in the absorbers which, if different from solar, can cause spurious shifts in the measured wavelengths and, therefore, alpha. Here we explore chemical evolution models with enhanced populations of intermediate-mass (IM) stars which, in their asymptotic giant branch (AGB) phase, are thought to be the dominant factories for heavy Mg isotopes at the low metallicities typical of quasar absorption systems. By design, these models partially explain recent Keck/HIRES evidence for a smaller alpha in z_abs < 2 absorption clouds than on Earth. However, such models also over-produce N, violating observed abundance trends in high-z_abs damped Lyman-alpha systems (DLAs). Our results do not support the recent claim of Ashenfelter, Mathews & Olive (2004...
Kotuš, Srđan M; Carswell, Robert F
2016-01-01
The brightest southern quasar above redshift $z=1$, HE 0515$-$4414, with its strong intervening metal absorption-line system at $z_{abs}=1.1508$, provides a unique opportunity to precisely measure or limit relative variations in the fine-structure constant ($\\Delta\\alpha/\\alpha$). A variation of just $\\sim$3 parts per million (ppm) would produce detectable velocity shifts between its many strong metal transitions. Using new and archival observations from the Ultraviolet and Visual Echelle Spectrograph (UVES) we obtain an extremely high signal-to-noise ratio spectrum (peaking at S/N $\\approx250$ pix$^{-1}$). This provides the most precise measurement of $\\Delta\\alpha/\\alpha$ from a single absorption system to date, $\\Delta\\alpha/\\alpha=-1.42\\pm0.55_{\\rm stat}\\pm0.65_{\\rm sys}$ ppm, comparable with the precision from previous, large samples of $\\sim$150 absorbers. The largest systematic error in all (but one) previous similar measurements, including the large samples, was long-range distortions in the wavelengt...
Structure of the group-constant-library GRUBA and its management by the program-system GRUMA
For nuclear calculations of Fast Reactors a chain of programs and associated data libraries has been established and successfully applied at KfK. Starting from energy-dependent probabilities for interactions between neutrons and isotopes, they allow to derive - as an intermediate step - averaged energygroup-dependent data stored on the GRUBA-file, which eventually are used to calculate the characteristic nuclear parameters of a reactor under investigation. The GRUBA-file contains material- and reaction-type-dependent group-cross-sections and similar quantities combined in a so called set of group-constants. The file is managed by the program-system GRUMA, which allows to open a new file and to change an existing one, to prepare input-files, to document changes and to print data contained in the GRUBA-file. For practical work with GRUMA and GRUBA the present report replaces the old report KfK 1815; it includes all new options of general character. (orig.)
Kiridena, Waruna; Patchett, Cheryl C; Koziol, Wladyslaw W; Poole, Colin F
2005-07-22
The solvation parameter model is used to characterize the retention properties of the bis(cyanopropylsiloxane)-co-methylsilarylene, HP-88, and poly(siloxane), Rtx-440, stationary phases over the temperature range 60-140 degrees C. HP-88 is among the most cohesive, dipolar/polarizable and hydrogen-bond basic of stationary phases for open-tubular column gas chromatography. It has no hydrogen-bond acidity or capacity for electron lone pair interactions. It exhibits similar selectivity to the poly(cyanopropylsiloxane) stationary phase SP-2340. Rtx-440 is a low-polarity, low-cohesion stationary phase with a moderate capacity for dipolar/polarizable and hydrogen-bond base interactions. It has no hydrogen-bond acidity and possesses weak electron lone pair interactions. It has unique selectivity when compared against a system constants database for 28 common stationary phase compositions. Cluster analysis indicated that the poly(cyanopropylphenyldimethylsiloxane) stationary phase containing 6% cyanopropylphenylsiloxane monomer, DB-1301, the poly(dimethyldiphenylsiloxane) stationary phase containing 20% diphenylsiloxane monomer, Rtx-20, the poly(siloxane) stationary phase of unknown composition, DB-624, and DX-1 [a mixture of poly(dimethylsiloxane) and poly(ethylene glycol) 9:1] are the closest selectivity matches in the database. The selectivity of DB-1301 and Rtx-440 are very similar for solutes with weak hydrogen-bond acidity allowing one stationary phase to be substituted for the other with likely success. For strong hydrogen-bond acids, such as phenols, DB-1301 and Rtx-440 exhibit different selectivity. PMID:16038217
Schröder, Henning; Sawall, Mathias; Kubis, Christoph; Selent, Detlef; Hess, Dieter; Franke, Robert; Börner, Armin; Neymeyr, Klaus
2016-07-13
If for a chemical reaction with a known reaction mechanism the concentration profiles are accessible only for certain species, e.g. only for the main product, then often the reaction rate constants cannot uniquely be determined from the concentration data. This is a well-known fact which includes the so-called slow-fast ambiguity. This work combines the question of unique or non-unique reaction rate constants with factor analytic methods of chemometrics. The idea is to reduce the rotational ambiguity of pure component factorizations by considering only those concentration factors which are possible solutions of the kinetic equations for a properly adapted set of reaction rate constants. The resulting set of reaction rate constants corresponds to those solutions of the rate equations which appear as feasible factors in a pure component factorization. The new analysis of the ambiguity of reaction rate constants extends recent research activities on the Area of Feasible Solutions (AFS). The consistency with a given chemical reaction scheme is shown to be a valuable tool in order to reduce the AFS. The new methods are applied to model and experimental data. PMID:27237834
Cosmological Constant, Fine Structure Constant and Beyond
Wei, Hao; Zou, Xiao-Bo; Li, Hong-Yu; Xue, Dong-Ze
2016-01-01
In this work, we consider the cosmological constant model $\\Lambda\\propto\\alpha^{-6}$, which is well motivated from three independent approaches. As is well known, the evidence of varying fine structure constant $\\alpha$ was found in 1998. If $\\Lambda\\propto\\alpha^{-6}$ is right, it means that the cosmological constant $\\Lambda$ should be also varying. In this work, we try to develop a suitable framework to model this varying cosmological constant $\\Lambda\\propto\\alpha^{-6}$, in which we view...
A method is presented for the calculation of association constants and the concentration of binding sites in a reaction of a ligand with a heterogeneous system of binding sites. The Scatchard plot for such a system is curvelinear and the method employs previously established relationships between the parameters of the limiting slopes to such a curve and the above mentioned association constants and concentrations of binding sites. The special case of a system with two different and non-interacting groups of binding sites was solved. The expressions thus obtained were used to characterize the reaction of a polypeptide neurotoxin with its specific binding sites in a membranal preparation from insect central nervous system. Moreover it is evident from these expressions that the widely accepted method to analyze such system, by an intuitive generalization of the method applicable to homogeneous systems, is erroneous and should be avoided. (author)
Heffler, Michael A.; Walters, Ryan D.; Kugel, Jennifer F.
2012-01-01
An undergraduate biochemistry laboratory experiment is described that will teach students the practical and theoretical considerations for measuring the equilibrium dissociation constant (K[subscript D]) for a protein/DNA interaction using electrophoretic mobility shift assays (EMSAs). An EMSA monitors the migration of DNA through a native gel;…
The effect of whole-body irradiation on Michaelis-Menten constants of the NADPH cytochrome P-450 reductase (EC1.6.2.3.), the oxidative demethylation of ethylmorphine and glucose 6-phosphatase (EC3.1.3.9.), have been studied at 1, 4 and 7 days after irradiation. (Auth.)
The reaction of the immune system on the constant exposure to the radiation of the Chernobyl discharge during the life of several generations of laboratory animals. It has been shown that the exposed animals (irrespective of the line, generation and sex) differ considerably from the controls both in definite immune characteristics (30-70% of the studied parameters) and in sensitivity to grippe virus
Jincai Wang
2007-01-01
We introduce the \\(J\\)-convexity constants on Banach spaces and give some properties of the constants. We give the relations between the \\(J\\)-convexity constants and the \\(n\\)-th von Neumann-Jordan constants. Using the quantitative indices we estimate the value of \\(J\\)-convexity constants in Orlicz spaces.
Eggert, Th.; Geilenkeuser, R.; Jäckel, M.
2000-07-01
We have measured the dielectric response ε( ω) and the thermal conductivity κ of polystyrene (PS) and of polycarbonate (PC) under high hydrostatic pressure (0.1 MPa
constant Ci can be determined. These results show that the product P¯γ l,t2 of the standard tunnelling model (STM) scales with the pressure-dependent elastic constants c11 and c44.
Criteria for the Degree of Stability of the Linear Constant Systems%线性定常系统稳定度的判据
王广彬; 潘宝珍; 侯文渊
2004-01-01
There are various applications of the stability theory of the first-order dynamical systems.And the stability of the non-linear control systems can be determined by its linear part.In practice, it is not enough to know the stability of the dynamical systems.Sometimes we must know the degree of stability of these systems.In this paper, we present some criteria for the degree of stability of the linear constant systems, by using the entries of the coefficient matrix A only.
杨德福
2016-01-01
Introduced the characteristics of the ancient library and HVAC system in the library of Liaoning Province, analyzes the scheme selection of the constant temperature and humidity air conditioning system and the cold and heat sources, summarizes the necessary technical measures and experience during the design of constant temperature and humidity air conditioning system, in order to provide a reference for design.%介绍了辽宁省图书馆古籍库及其暖通空调系统的特点，分析了其恒温恒湿空调系统方案选择及冷热源选择，总结了古籍库恒温恒湿空调系统设计的必要技术措施和体会，以供设计参考。
As of February 3, 1975, 175 neutron group constants had been derived from the Evaluated Nuclear Data Library (ENDL) at LLL. In this volume, tables and graphs of the constants are presented along with the conventions used in their preparation. (U.S.)
Fannin, Paul C.; Coffey, William T.
2000-03-01
Measurements are presented of the complex magnetic susceptibility,\\chi (ω) = \\chi' (ω )- i\\chi'' (ω ), of a number of colloidal suspensions of nano-particles with different packing fractions, over the frequency range 10kHz to 18kHz. The magnetic field dependence of the average particle anisotropy constant, K, for magnetic fluids samples of magnetite in isopar M for seventeen values of polarising field, H, in the approximate range 0 to 100,000 A/m are presented and examined.
无
2007-01-01
In this paper, the air-water vapor-water system is taken as an example, and the formula of constantpressure specific heat during non-equilibrium phase change process in the two-phase flow system is deduced using the theory of two-phase flow and thermophysics. The constant-pressure specific heat of non-equilibrium phase change process is calculated with the corresponding numerical model, and the numerical results are compared to those of the equilibrium phase change process. It is shown that in evaporation process, the variational rate of the non-equilibrium specific heat increases with increasing initial fluid temperature and particle mass fraction. The smaller particle radius is, the faster the variational rate is. Meanwhile, the constant-pressure specific heat of equilibrium process is higher than that of the non-equilibrium process all the time.
Cosmological Hubble constant and nuclear Hubble constant
The evolution of the Universe after the Big Bang and the evolution of the dense and highly excited nuclear matter formed by relativistic nuclear collisions are investigated and compared. Values of the Hubble constants for cosmological and nuclear processes are obtained. For nucleus-nucleus collisions at high energies the nuclear Hubble constant is obtained in the frame of different models involving the hydrodynamic flow of the nuclear matter. Significant difference in the values of the two Hubble constant - cosmological and nuclear - is observed
The purpose of this paper is to examine the qualification of few group constants estimated by the Seoul National University Monte Carlo particle transport analysis code McCARD in terms of core neutronics analyses and thus to validate the McCARD method as a few group constant generator. The two- step core neutronics analyses are conducted for a mini and a realistic PWR by the McCARD/MASTER code system in which McCARD is used as an MC group constant generation code and MASTER as a diffusion core analysis code. The two-step calculations for the effective multiplication factors and assembly power distributions of the two PWR cores by McCARD/MASTER are compared with the reference McCARD calculations. By showing excellent agreements between McCARD/MASTER and the reference MC core neutronics analyses for the two PWRs, it is concluded that the MC method implemented in McCARD can generate few group constants which are well qualified for high-accuracy two-step core neutronics calculations. (author)
Highlights: • A new set of Henry’s constant for the system carbon dioxide-aqueous deep eutectic solvents were measured. • The DESs used were: ethaline, glyceline, and maline. • The measured data were reported as functions of temperature and composition. • The measured data were represented satisfactorily by the applied correlations. -- Abstract: In this study, we present a new set of Henry’s constant data for the system carbon dioxide-aqueous deep eutectic solvent (DES) (20 to 80 wt% DES) at T = (303.15, 308.15, and 313.15) K. The DESs used were choline chloride-based: ethaline (choline chloride/ethylene glycol), glyceline (choline chloride/glycerol), and maline (choline chloride/malonic acid). A differential Henry’s coefficient model was used to describe the behaviour of Henry’s constant, and correlate it with temperature and concentration of DES in the aqueous DES solution. The correlation was found satisfactory such that the proposed model can be used in engineering calculations with reasonable accuracy
The constant system for multiparticle radiation transport and macro- and micromodels of the hh, hA, and AA interactions implemented in the form of a set of hadronic generators, included in the current version of the RTS&T-2013 code system intended for the statistical modeling of multi-particle radiation transport in heterogeneous 3D geometries in a wide energy range has been considered. Selective results of systematic testing of the code on the basis of integral benchmarks for typical problems of radiation transport are given for intermediate- and high-energy ranges
Ion exchange equilibrium constants
Marcus, Y
2013-01-01
Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and
Surfaces of a Constant Negative Curvature
G. M. Gharib
2012-01-01
Full Text Available I study the geometric notion of a differential system describing surfaces of a constant negative curvature and describe a family of pseudospherical surfaces for the nonlinear partial differential equations with constant Gaussian curvature .
Nadia Afrin; Monirul Islam; Anarul Islam
2015-01-01
Recently, transformerless inverters are becoming more attractive for grid-tied photovoltaic (PV) system because of high efficiency and low cost. Unfortunately, leakage current may flow through the whole grid-tied PV system due to fluctuating common mode (CM) voltage that depends on the topology structure and control strategy. Therefore, to meet the safety regulations, leakage current of transformerless PV inverter has to be addressed carefully. In this paper, a new microcontroller based trans...
Lie, Svenn Arne
2006-01-01
When studying the party system formation in post-communist Lithuania, the Western European theoretical framework is a useful, although not sufficient tool to understand this process. Weak alignments between voters and parties and unstable party systems have made it difficult to apply the Western European theoretical framework because it prerequisites a high degree of party institutionalisation. In addition to unstable electoral support for the established parties, new parties s...
A modular code system RADHEAT-V4 has been developed for performing precisely neutron and photon transport analyses, and shielding safety evaluations. The system consists of the functional modules for producing coupled multi-group neutron and photon cross section sets, for analyzing the neutron and photon transport, and for calculating the atom displacement and the energy deposition due to radiations in nuclear reactor or shielding material. A precise method named Direct Angular Representation (DAR) has been developed for eliminating an error associated with the method of the finite Legendre expansion in evaluating angular distributions of cross sections and radiation fluxes. The DAR method implemented in the code system has been described in detail. To evaluate the accuracy and applicability of the code system, some test calculations on strong anisotropy problems have been performed. From the results, it has been concluded that RADHEAT-V4 is successfully applicable to evaluating shielding problems accurately for fission and fusion reactors and radiation sources. The method employed in the code system is very effective in eliminating negative values and oscillations of angular fluxes in a medium having an anisotropic source or strong streaming. Definitions of the input data required in various options of the code system and the sample problems are also presented. (author)
Bordé, Christian J
2016-01-01
Our purpose is to offer a logical analysis of the system of units and to explore possible paths towards a consistent and unified system with an original perspective. The path taken here builds on the fact that, thanks to optical or matter-wave interferometry, any measurement can be reduced to a dimensionless phase measurement and we follow this simple guiding line. We finally show how one could progress even further on the path of a synthetic framework for fundamental metrology based upon pure geometry in five dimensions.
Results of calculations of critical assemblies with the cores of uranium solutions for the considered series of the experiments are presented in this paper. The conclusions about acceptability of the ABBN-93.1 cross sections for the calculations of such systems are made. (author)
Photoformation rates and scavenging rate constants of hydroxyl radicals (·OH) in natural water samples were determined by an automatic determination system. After addition of benzene as a chemical probe to a water sample in a reaction cell, light irradiation and injection of irradiated water samples into an HPLC as a function of time were performed automatically. Phenol produced by the reaction between ·OH and the benzene added to the water sample was determined to quantify the ·OH formation rate. The rate constants of ·OH formation from the photolysis of nitrate ions, nitrite ions and hydrogen peroxide were comparable with those obtained in previous studies. The percent of expected ·OH photoformation rate from added nitrate ion were high in drinking water (97.4%) and river water (99.3%). On the other hand, the low percent (65.0%) was observed in seawater due to the reaction of ·OH with the high concentrations of chloride and bromide ions. For the automatic system, the coefficient of variance for the determination of the ·OH formation rate was less than 5.0%, which is smaller than that in the previous report. When the complete time sequence of analytical cycle was 40 min for one sample, the detection limit of the photoformation rate and the sample throughput were 8 x 10-13 M s-1 and 20 samples per day, respectively. The automatic system successfully determined the photoformation rates and scavenging rate constants of ·OH in commercial drinking water and the major source and sink of ·OH were identified as nitrate and bicarbonate ions, respectively
System of constants to calculate neutron transport with energy 10-2-4x108 eV
A description of the library of nuclear data to calculate neutron transport in the energy range 10-2 eV-4x102 MeV (BND-400) is presented. The library contains a seven-group system of data for neutrons of E>10.5 MeV and a standard 26-group system for neutrons with E10.5 MeV, and those for matching with the file of data for neutrons with E<10.5 MeV are briefly described. In the BND-400 complex there are subroutines, which allow one to calculate the cross sections for neutron interaction with nuclei of matter with the help of various methods and models as well as to calculate group cross sections. It also provides output files in the form convenient for work. A brief instruction for BND-400 explotation on the computer BESM-6 is given
Varying Constants, Gravitation and Cosmology
Jean-Philippe Uzan
2011-03-01
Full Text Available Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.
Spruit, Martijn A.; Troosters, Thierry; Gosselink, Rik; Kasran, Ahmad; Decramer, Marc
2007-01-01
Study objectives: To explore the acute systemic inflammatory and anabolic effects of cycling in hospital admitted patients with chronic obstructive pulmonary disease (COPD) and in patients with clinically stable disease. Design: Cross-sectional comparative study. Setting: University Hospital Gasthuisberg, a tertiary care setting. Patients: 16 patients with clinically stable COPD (no acute exacerbation in the past 12 weeks; median age: 73 years (IQR: 60 to 75); median forced expiratory volume ...
De Martino, Salvatore; De Siena, Silvio; Illuminati, Fabrizio
1999-01-01
The possibility is discussed of inferring or simulating some aspects of quantum dynamics by adding classical statistical fluctuations to classical mechanics. We introduce a general principle of mechanical stability and derive a necessary condition for classical chaotic fluctuations to affect confined dynamical systems, on any scale, ranging from microscopic to macroscopic domains. As a consequence we obtain, both for microscopic and macroscopic aggregates, dimensional relations defining the m...
Nadia Afrin
2015-06-01
Full Text Available Recently, transformerless inverters are becoming more attractive for grid-tied photovoltaic (PV system because of high efficiency and low cost. Unfortunately, leakage current may flow through the whole grid-tied PV system due to fluctuating common mode (CM voltage that depends on the topology structure and control strategy. Therefore, to meet the safety regulations, leakage current of transformerless PV inverter has to be addressed carefully. In this paper, a new microcontroller based transformerless topology with low leakage current is proposed for grid-tied PV system. A 16-bit dSPIC microcontroller is implemented to control the proposed topology. The proposed circuit structure and detail operation principle are presented in this paper. One additional switch with conventional full-bridge inverter and a diode clamping branch ensure the disconnection of PV module from the grid at the freewheeling mode and clamp the short-circuited output voltage to the half of DC input voltage. Therefore, the CM leakage current is minimized considerably. Meanwhile, MOSFET switches have been used in the proposed inverter to improve the efficiency at light-load condition. Finally, a prototype has been developed to verify the theoretical analysis and the experimental results show that the performance of the proposed inverter is as expected. It is found that the maximum efficiency and European efficiency of the proposed inverter is 98% and 97.52%, respectively.
Physics without physical constants
Following the general principles of both Newton's mechanics and Maxwell's electrodynamics, a new approach to basic equations of physics is presented. The new basic equations express fundamental laws of physics and are free from any physical constants. The necessary constants appear only through some kind of constitutive relations and by considering special solutions of the basic equations. The presented approach admits a new interpretation of fundamental physical constants, such as the Planck gravitational ones. 4 refs. (author)
S. M. Tebcheran
2003-04-01
in small concentrations as densifying aids for this oxide. In the present study the sintering kinetics of tin oxide was studied considering the effect of sintering atmosphere and of the MnO2 concentration. SnO2-MnO2 systems were prepared from the polymeric precursors method and the obtained powders were characterized by surface area by the BET method. SnO2 powders with varied MnO2 concentrations were pressed in cylindrical shape, and sintered in a dilatometer furnace with constant heating rate and controlled atmospheres. Sintered samples were characterized by scanning electron microscopy. The influence of atmosphere (argon, air or CO2 as well as of the MnO2 concentrations on the sintering kinetics was determined. The kinetics data of linear shrinkage were analyzed in terms of kinetic models for the initial stage of sintering (Woolfrey and Bannister as well as for the global sintering (Su e Johnson allowing the determination of the apparent activation energy. Following the determination of the master sintering curve the apparent activation energy of all sintering process were determined as well as its dependence with the atmosphere and manganese concentrations. Based on these values and on the n exponent, determined by the classical grain growth equation, it was concluded that the most probable sintering mechanism is grain boundary diffusion with surface redistribution controlling the kinetics.
The library of atomic masses and characteristic constants for nuclear ground states, a sub-library of Chinese Evaluated Nuclear Parameter Library (CENPL), consists of two parts: the data file and management-retrieval code system. The former stores the nuclear basic data, such as the mass excesses, abundances and half-lives, spines and parities of the nuclear ground states. The latter is developed to retrieve the data stored in the data file. It can also derive the separation energies of some particles and particle groups and β-decay energies; nuclear reaction energies and the corresponding threshold energies for some neutron reaction channels including the third reaction process could also be obtained as combinations of different mass excesses. The function, feature and operation instruction of the code system are described briefly
Carroll Sean M.
2001-01-01
Full Text Available This is a review of the physics and cosmology of the cosmological constant. Focusing on recent developments, I present a pedagogical overview of cosmology in the presence of a cosmological constant, observational constraints on its magnitude, and the physics of a small (and potentially nonzero vacuum energy.
Local Experiments See Cosmologically Varying Constants
Shaw, D J; Barrow, John D.; Shaw, Douglas J.
2006-01-01
We describe a rigorous construction, using matched asymptotic expansions, which establishes under very general conditions that local terrestrial and solar-system experiments will measure the effects of varying `constants' of Nature occurring on cosmological scales to computable precision. In particular, `constants' driven by scalar fields will still be found to evolve in time when observed within virialised structures like clusters, galaxies, and planetary systems. This provides a justification for combining cosmological and terrestrial constraints on the possible time variation of many assumed `constants' of Nature, including the fine structure constant and Newton's gravitation constant.
Whit the objective of to complete the existent techniques for susceptibility evaluation to phenomenon of stress corrosion cracking in laboratories of Applied Sciences Area of National Institute of Nuclear Research; was realized and documented the modification of a high pressure and temperature equipment, identified as MEX-03 to carry out the implementation of a growth and crack propagation assay, using a constant load method. The assay was realized to a specimen of stainless steel AISI 304l type CT of an inch, which was previously thermally sensitize, simulating the typical degradation of this materials type below operation conditions in a BWR. The MEX-03 system, consist from an annexed auto key to a load system which originally was controlled by displacement; therefore were carried out modifications to achieve the control by load. The realized adjustments allowed to maintain a constant load during all the experiment, and as much the temperature conditions (T = 288 C) as of pressure (P = 8 Mpa) were controlled during the assay realization. The steel was exposed to a conditioned ambient with hydrogen gas addition; simulating a well-known alternative chemistry as hydrogen water chemistry that is used to mitigate the phenomenon of stress corrosion cracking, main degradation mechanism of austenitic stainless steels. The continuation of the crack behavior was realized by means of electric potential fall technique and later was validated of visual form through the fractographic analysis of cracked surface. The modification and control of equipment for realization of this experiment is necessary, for what should be carried out new assays, whose results will allow to establish the effect of dynamic and static methods in velocity determination of crack growth to laboratory level; to be considered in the existent models of crack propagation in systems and components in operation. (Author)
Ziganshin, Ayrat M; Schmidt, Thomas; Lv, Zuopeng; Liebetrau, Jan; Richnow, Hans Hermann; Kleinsteuber, Sabine; Nikolausz, Marcell
2016-10-01
The effects of hydraulic retention time (HRT) reduction at constant high organic loading rate on the activity of hydrogen-producing bacteria and methanogens were investigated in reactors digesting thin stillage. Stable isotope fingerprinting was additionally applied to assess methanogenic pathways. Based on hydA gene transcripts, Clostridiales was the most active hydrogen-producing order in continuous stirred tank reactor (CSTR), fixed-bed reactor (FBR) and anaerobic sequencing batch reactor (ASBR), but shorter HRT stimulated the activity of Spirochaetales. Further decreasing HRT diminished Spirochaetales activity in systems with biomass retention. Based on mcrA gene transcripts, Methanoculleus and Methanosarcina were the predominantly active in CSTR and ASBR, whereas Methanosaeta and Methanospirillum activity was more significant in stably performing FBR. Isotope values indicated the predominance of aceticlastic pathway in FBR. Interestingly, an increased activity of Methanosaeta was observed during shortening HRT in CSTR and ASBR despite high organic acids concentrations, what was supported by stable isotope data. PMID:26853042
Vidal, C. R.; Stwalley, W. C.
1982-01-01
The molecular constants and their adiabatic corrections have been determined for the (A 1 Sigma +) - (X 1 Sigma +) system of the isotopic lithium hydrides: (Li-6)H, (Li-7)H, (Li-6)D, and (Li-7)D. Using a fully quantum mechanical variational method, the potential energy curves (IPA potentials) are determined. Extending the variational method, we have obtained for the first time adiabatic corrections of potential energy curves from isotopic spectroscopic data. A significant difference between the potential energy curves of the lithium hydrides and the lithium deuterides has been observed. When Li-6 was replaced by Li-7, a significant difference was only observed for the (A 1 Sigma +) state, but not for the (X 1 Sigma +) state.
PET systems need good time resolution to improve the true event rate, random event rejection, and pile-up rejection. In this study we propose a digital procedure for this task using a low pass filter interpolation plus a Digital Constant Fraction Discriminator (DCFD). We analyzed the best way to implement this algorithm on our dual head PET system and how varying the quality of the acquired signal and electronic noise analytically affects timing resolution. Our detector uses two continuous LSO crystals with a position sensitive PMT. Six signals per detector are acquired using an analog electronics front-end and these signals are processed using an in-house digital acquisition board. The test bench developed simulates the electronics and digital algorithms using Matlab. Results show that electronic noise and other undesired effects have a significant effect on the timing resolution of the system. Interpolated DCFD gives better results than non-interpolated DCFD. In high noise environments, differences are reduced. An optimum delay selection, based on the environment noise, improves time resolution.
A constant of motion is defined for a one-dimensional and nth-differenital-order autonomous svstem. A generalization of the Legendre transformation is given that allows one to obtain a relation among the constant of motion the Lagrangian, and the Hamiltonian. The approach is used to obtain the constant of motion associated with the nonrelativistic third-differential-order Abraham-Lorentz radiation damping equation
JSSTDL 295n-104γ: A common group cross-section library system has been developed in JAERI to be used in fairly wide range of applications in nuclear industry. This system is composed of a common 295n-104γ group cross-section library based on JENDL-3 nuclear data file and its utility codes. Target of this system is focused to the criticality or shielding calculations in fast and fusion reactors using ANISN, DOT, or MORSE code. Specifications of the common group constants were decided responding to the request from various nuclear data users, particularly from nuclear design group in Japan. Group structure is decided so as to cover almost all group structures currently used in our country. This library includes self-shielding factor tables for primary reactions. A routine for generating macro-scopic cross-section using the self-shielding factor table is also provided. Neutron cross-sections and photon production cross-sections are processed by Prof. GROUCH-G/B code system and γ ray transport cross-sections are generated by GAMLEG-JR. In this paper, outline and present status of the JSSTDL library system is described along with two examples adopted in JENDL-3 benchmark test. One is for shielding calculation, where effects of self-shielding factor (f-table) is shown in conjunction with the analysis of the ASPIS natural iron deep penetration experiment. Without considering resonance self-shielding effect in resonance energy region for resonant nuclides like iron, the results is completely missled in the attenuation profile calculation in the shields. The other example is fast rector criticality calculations of very small critical assemblies with very high enrichment fuel materials where some basic characteristics of this library is presented. (orig.)
Dielectric Constant of Suspensions
Mendelson, Kenneth S.; Ackmann, James J.
1997-03-01
We have used a finite element method to calculate the dielectric constant of a cubic array of spheres. Extensive calculations support preliminary conclusions reported previously (K. Mendelson and J. Ackmann, Bull. Am. Phys. Soc. 41), 657 (1996).. At frequencies below 100 kHz the real part of the dielectric constant (ɛ') shows oscillations as a function of the volume fraction of suspension. These oscillations disappear at low conductivities of the suspending fluid. Measurements of the dielectric constant (J. Ackmann, et al., Ann. Biomed. Eng. 24), 58 (1996). (H. Fricke and H. Curtis, J. Phys. Chem. 41), 729 (1937). are not sufficiently sensitive to show oscillations but appear to be consistent with the theoretical results.
Algorithm for structure constants
Paiva, F M
2011-01-01
In a $n$-dimensional Lie algebra, random numerical values are assigned by computer to $n(n-1)$ especially selected structure constants. An algorithm is then created, which calculates without ambiguity the remaining constants, obeying the Jacobi conditions. Differently from others, this algorithm is suitable even for poor personal computer. ------------- En $n$-dimensia algebro de Lie, hazardaj numeraj valoroj estas asignitaj per komputilo al $n(n-1)$ speciale elektitaj konstantoj de strukturo. Tiam algoritmo estas kreita, kalkulante senambigue la ceterajn konstantojn, obeante kondicxojn de Jacobi. Malsimile al aliaj algoritmoj, tiu cxi tauxgas ecx por malpotenca komputilo.
Nobrega, Juraci Carlos de Castro
1989-07-01
The stead-state analysis of a Wind Energy Conversion Systems, consisting on a Windmill, Synchronous Generator, transmission Line and Induction Motor driving a Centrifugal Pump is developed. The performance of the system operating at variable Speed with a flux control is examined using mathematical and digital simulation. The control scheme is proposed and tested in laboratory and a tested in laboratory and a test centre to be compared with simulation results. (author)
Microscopic group constants determination
The method of microscopic group constants determination for nuclear reactor calculations is described in this paper. The principle of this method is group averaging of microscopic cross sections with respect to the standard spectrum. The group cross sections obtained are used for the calculation of fast critical assembly Jezebel. (author)
1995-08-01
about the distances to galaxies and thereby about the expansion rate of the Universe. A simple way to determine the distance to a remote galaxy is by measuring its redshift, calculate its velocity from the redshift and divide this by the Hubble constant, H0. For instance, the measured redshift of the parent galaxy of SN 1995K (0.478) yields a velocity of 116,000 km/sec, somewhat more than one-third of the speed of light (300,000 km/sec). From the universal expansion rate, described by the Hubble constant (H0 = 20 km/sec per million lightyears as found by some studies), this velocity would indicate a distance to the supernova and its parent galaxy of about 5,800 million lightyears. The explosion of the supernova would thus have taken place 5,800 million years ago, i.e. about 1,000 million years before the solar system was formed. However, such a simple calculation works only for relatively ``nearby'' objects, perhaps out to some hundred million lightyears. When we look much further into space, we also look far back in time and it is not excluded that the universal expansion rate, i.e. the Hubble constant, may have been different at earlier epochs. This means that unless we know the change of the Hubble constant with time, we cannot determine reliable distances of distant galaxies from their measured redshifts and velocities. At the same time, knowledge about such change or lack of the same will provide unique information about the time elapsed since the Universe began to expand (the ``Big Bang''), that is, the age of the Universe and also its ultimate fate. The Deceleration Parameter q0 Cosmologists are therefore eager to determine not only the current expansion rate (i.e., the Hubble constant, H0) but also its possible change with time (known as the deceleration parameter, q0). Although a highly accurate value of H0 has still not become available, increasing attention is now given to the observational determination of the second parameter, cf. also the Appendix at the
A new definition for the electrochemical cell constant in conductivity measurements is presented in this paper. Electrochemical Impedance Spectroscopy and DC pulses measurements have been carried out in non-Faradaic conditions in order to evaluate the effects of the cell geometry. The results obtained demonstrate that conductivity measurements are affected not only by the electrodes surface and separation but also by the cross section of the electrochemical cell. In order to obtain a linear behavior of the resistance versus the distance between electrodes, the cross section of the cell should be equal to the electrodes surface. Differences between the cell cross section and the electrodes surface produce a heterogeneous distribution of the electric field that causes the non-linear behavior for low values of the electrodes separation. This study shows that the reproducibility in electronic tongue and humid electronic nose measurements can be improved by designing an electrochemical cell structure that warrants a homogeneous distribution of the electrical field, which results in a reduction of the detection threshold in these types of system
Studies in the system MgO-SiO2-CO2-H2O(I): The activity-product constant of chrysotile
Hostetler, P.B.; Christ, C.L.
1968-01-01
Chrysotile dissolves congruently in water according to the reaction: Mg3Si2O6(OH)4c + 5H2Ol = 3Mgaq2+ + 6OHaq- + 2H4SiO4aq. Experimental determination of the activity-product constant of chrysotile, Kchr = [Mg2+]3[OH-]6[H4SiO4aq]2, at 90??C, yields the value of Kchr = 10-49.2 ?? 100.5. A synthetic sample and a natural sample from New Idria, California, were used in the determination. Values of Kchr were calculated for temperatures ranging from 0??C to 200??C, using the thermochemical data of King et al. (1967) for chrysotile and antigorite, various solubility data for silica, and ionic partial molal heat capacities estimated by the method of criss and Cobble (1964a). Kchr is 10-54.1 at 0??C, rises to a maximum value of 10-48.5 at approximately 135??C, and is 10-49.1 at 200??C (all values for the three-phase system, chrysotile plus solution plus vapor). The calculated 90??C value is 10-49.1, in excellent agreement with the experimental value; for 25??C, the calculated value is 10-50.8. ?? 1968.
Ammonia and volatile organic amines are used to treat the water in steam generating systems to afford protection of the steam and feedwater circuits from corrosion by acidic condensate. The base strength and the volatility of the reagent used are two important parameters that have bearing on its ability to inhibit corrosion; they determine the pH of the solution produced from condensing steam. The distribution of thirteen amines between water and steam in the temperature range 150 to 325 degree C was studied. The amines were chosen on the basis of their known room temperature base strength. The acid ionization constants (Ka) of the ammonium salts of seven of these amines were determined by conductivity measurement in the temperature range 25 to 275 degree C. Amines with high room temperature base strength and distribution coefficient in the optimum range were chosen for the high-temperature base strength determination. The results of these studies were used to estimate the effectiveness of these amines in raising the pH of the condensate from steam containing carbon dioxide and acetic acid in order to provide the basis for further studies on the corrosion inhibition properties of the amines
Variation of fundamental constants
Flambaum, V V
2006-01-01
We present a review of recent works devoted to the variation of the fine structure constant alpha, strong interaction and fundamental masses. There are some hints for the variation in quasar absorption spectra, Big Bang nucleosynthesis, and Oklo natural nuclear reactor data. A very promising method to search for the variation of the fundamental constants consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transition between accidentally degenerate atomic and molecular energy levels. A new idea is to build a ``nuclear'' clock based on the ultraviolet transition between very low excited state and ground state in Thorium nucleus. This may allow to improve sensitivity to the variation up to 10 orders of magnitude! Huge enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feschbach resonance.
Perdomo, Oscar M
2013-01-01
In this paper we show all possible ramps where an object can move with constant speed under the effect of gravity and friction. The planar ramp are very easy to describe, just rotate a curve with velocity vector (tanh(as),sech(as)). Recall that tanh(as)^2+sech^2(as) = 1. Therefore, the solution of the planar constant speed problem is connected with easy to describe examples of curves with arc-length parameter. For ramps in the space, we show that there are as many ramps as tangent unit vector fields in the south hemisphere. A video explaining these results can be found at http://www.youtube.com/watch?v=iBrvbb0efVk
Aurich, R.; Steiner, F.
1992-07-01
Dynamical zeta functions, defined as Euler products over classical periodic orbits, have recently received enhanced attention as an important tool for the quantization of chaos. Their representation as a Dirichlet series over pseudo-orbits has proven to be particularly useful, since these series seem to possess in the general case much better convergence properties than the original Euler product. The convergence of the Dirichlet series depends crucially on the asymptotic distribution of the pseudo-orbits and thus on the ergodicity of the underlying dynamical system. It is shown that the lengths ln (or rather expln) of the classical periodic orbits play mathematically the role of generalized prime numbers. Based on the theory of Beurling's generalized prime numbers, we derive an exact law for the proliferation of psuedo-orbits for the Hadamard-Gutzwiller model, which is one of the main testing grounds of our ideas about quantum chaos. The strength of growth of the pseudo-orbits is determined by the ratio ZETA(2)/ZETA'(1), where ZETA(s) denotes the Selberg zeta function. Two explicit, complementary representations are given that allow the computation of this ratio solely from the length spectrum \\{ln\\} of the classical periodic orbits, or from the quantal energy spectrum \\{En\\}. One of these relations depends exponentially on the generalized Euler constant γΔ, which is therefore also studied. The formulas are applied to two strongly chaotic systems. It turns out that our asymptotic law describes the mean proliferation of pseudo-orbits very well not only in the asymptotic region, but also surprisingly well down to the shortest pseudo-orbit.
The cosmological constant puzzle
Bass, Steven D.
2011-01-01
Abstract The accelerating expansion of the Universe points to a small positive vacuum energy density and negative vacuum pressure. A strong candidate is the cosmological constant in Einstein's equations of General Relativity. Possible contributions are zero-point energies and the condensates associated with spontaneous symmetry breaking. The vacuum energy density extracted from astrophysics is 10 56 times smaller than the value expected from quantum fields and Standard Model particle physi...
Small fluctuations in the solar constant can occur on timescales much shorter than the Kelvin time. Changes in the ability of convection to transmit energy through the superadiabatic and transition regions of the convection zone cause structure adjustments which can occur on a time scale of days. The bulk of the convection zone reacts to maintain hydrostatic equilibrium (though not thermal equilibrium) and causes a luminosity change. While small radius variations will occur, most of the change will be seen in temperature
U.S. Geological Survey, Department of the Interior — This digital data set represents the constant head-boundary used to simulate ground-water inflow or outflow at the lateral boundary of the Death Valley regional...
Burant, Aniela; Lowry, Gregory V; Karamalidis, Athanasios K
2016-02-01
Treatment and reuse of brines, produced from energy extraction activities, requires aqueous solubility data for organic compounds in saline solutions. The presence of salts decreases the aqueous solubility of organic compounds (i.e. salting-out effect) and can be modeled using the Setschenow Equation, the validity of which has not been assessed in high salt concentrations. In this study, we used solid-phase microextraction to determine Setschenow constants for selected organic compounds in aqueous solutions up to 2-5 M NaCl, 1.5-2 M CaCl2, and in Na-Ca binary electrolyte solutions to assess additivity of the constants. These compounds exhibited log-linear behavior up to these high NaCl concentrations. Log-linear decreases in solubility with increasing salt concentration were observed up to 1.5-2 M CaCl2 for all compounds, and added to a sparse database of CaCl2 Setschenow constants. Setschenow constants were additive in binary electrolyte mixtures. New models to predict CaCl2 and KCl Setschenow constants from NaCl Setschenow constants were developed, which successfully predicted the solubility of the compounds measured in this study. Overall, data show that the Setschenow Equation is valid for a wide range of salinity conditions typically found in energy-related technologies. PMID:26598993
陈逸; 孙剑波; 韦忠朝
2012-01-01
在matlab／simulink中对一台三相12／8极开关磁阻发电机的变速恒压工作情况进行了建模仿真，通过SRMFEM建立了开关磁阻发电机非线性本体模型，这在一定程度上保证了仿真结果的准确性在自励发电模式下，通过对电压、电流的两点式闭环，探讨了变速恒压情况下开关磁阻发电机的动静态响应．仿真结果表明：开关磁阻发电系统在变速的情况下依然有很不错的发电特性．但是，在仿真结果中，同样也可以发现，因为开关磁阻发电机是一个多变量、强耦合的非线性系统，在能量转换的过程中，虽然有滤波电容的平波作用，输出直流电压的脉动还是无法避免，在一些应用要求较高的场合，须在动态响应和发电质量两者之间权衡优化控制策略及相关拓扑电路的设计是下一步研究的问题．%Due to the characteristics of high reliability, wide speed scope with high efficiency, and low cost, Switched Reluctance Generator （SRG） system is suitable for applications in the field of variable-speed con- stant-voltage generation, such as wind power generation, flywheel energy storage, electric vehicle, aircraft power generator, and so on. In this paper, a nonlinear model of SRG was established by means of Matlab/ Simulink. Furthermore, a power generation plan of SRG about variable-speed constant-voltage generation control system was designed. Variable-speed simulation results show that the control system has favorable dynamic and static characteristics.
Juliana Sousa Coelho
2012-05-01
Full Text Available Trata-se de um ensaio que expõe reflexões sobre a busca e o exercício da participação social no Sistema Único de Saúde (SUS, compreendendo seu conceito como as diferentes ações dos grupos sociais que influenciam a formulação, execução, fiscalização e avaliação das políticas públicas. Por isso o fato de a comunidade participar no sistema de saúde é visto como condição fundamental para o exercício pleno da saúde, capaz de promover equidade e de transformar a atenção à saúde. As ações de construir a cidadania e formar sujeitos coletivos são tomadas como fundamentos para a conquista de espaços democráticos e de direitos sociais. Mapeou-se a normatização atual referente à participação popular, considerando seus avanços, mas explicitando também suas fragilidades, principalmente no que tange aos conselhos e conferências de saúde. No ambiente dos espaços institucionais de participação, foram destacados elementos necessários para consolidar e efetivar a participação popular, como a relação entre os atores e a comunicação para a socializar as informações e conhecimentos em saúde. Busca-se também problematizar o assunto, trazendo à tona alguns dos obstáculos e críticas relativos à participação social. Pretende-se, com este ensaio, colaborar para a democratização dos diferentes espaços de escuta da sociedade civil, tornando-os locais cada vez mais apropriados para as tomadas de decisão sobre a construção de políticas e serviços de saúde, dos quais a população se apropria coletivamente, superando a simples obrigatoriedade burocrática da participação e contribuindo para a saúde e qualidade de vida.It concerns an essay that presents reflections on the search and the practice of the social participation in the Brazilian Unified Health System (SUS, including the understanding of its concept as to how the different actions of the social groups influence the formularization, execution
Neal Jackson
2015-09-01
Full Text Available I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give H_0 values of around 72–74 km s^–1 Mpc^–1, with typical errors of 2–3 km s^–1 Mpc^–1. This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67–68 km s^–1 Mpc^–1 and typical errors of 1–2 km s^–1 Mpc^–1. The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.
Approximations to Euler's constant
We study a problem of finding good approximations to Euler's constant γ=lim→∞ Sn, where Sn = Σk=Ln (1)/k-log(n+1), by linear forms in logarithms and harmonic numbers. In 1995, C. Elsner showed that slow convergence of the sequence Sn can be significantly improved if Sn is replaced by linear combinations of Sn with integer coefficients. In this paper, considering more general linear transformations of the sequence Sn we establish new accelerating convergence formulae for γ. Our estimates sharpen and generalize recent Elsner's, Rivoal's and author's results. (author)
Schlamminger, Stephan; Seifert, Frank; Chao, Leon S; Newell, David B; Liu, Ruimin; Steiner, Richard L; Pratt, Jon R
2014-01-01
For the past two years, measurements have been performed with a watt balance at the National Institute of Standards and Technology (NIST) to determine the Planck constant. A detailed analysis of these measurements and their uncertainties has led to the value $h=6.626\\,069\\,79(30)\\times 10^{-34}\\,$J$\\,$s. The relative standard uncertainty is $ 45\\times 10^{-9}$. This result is $141\\times 10^{-9}$ fractionally higher than $h_{90}$. Here $h_{90}$ is the conventional value of the Planck constant given by $h_{90}\\equiv 4 /( K_{\\mathrm{J-90}}^2R_{\\mathrm{K-90}})$, where $K_{\\mathrm{J-90}}$ and $R_{\\mathrm{K-90}}$ denote the conventional values of the Josephson and von Klitzing constants, respectively.
Local experiments see cosmologically varying constants
We describe a rigorous matched asymptotic expansion, which establishes under very general conditions that local terrestrial and solar-system experiments will measure any variations in 'constants' of Nature occurring on cosmological scales
Markov constant and quantum instabilities
Pelantová, Edita; Starosta, Štěpán; Znojil, Miloslav
2016-04-01
For a qualitative analysis of spectra of certain two-dimensional rectangular-well quantum systems several rigorous methods of number theory are shown productive and useful. These methods (and, in particular, a generalization of the concept of Markov constant known in Diophantine approximation theory) are shown to provide a new mathematical insight in the phenomenologically relevant occurrence of anomalies in the spectra. Our results may inspire methodical innovations ranging from the description of the stability properties of metamaterials and of certain hiddenly unitary quantum evolution models up to the clarification of the mechanisms of occurrence of ghosts in quantum cosmology.
Constant Proportion Portfolio Insurance
Jessen, Cathrine
2014-01-01
Portfolio insurance, as practiced in 1987, consisted of trading between an underlying stock portfolio and cash, using option theory to place a floor on the value of the position, as if it included a protective put. Constant Proportion Portfolio Insurance (CPPI) is an option-free variation on the...... theme, originally proposed by Fischer Black. In CPPI, a financial institution guarantees a floor value for the “insured” portfolio and adjusts the stock/bond mix to produce a leveraged exposure to the risky assets, which depends on how far the portfolio value is above the floor. Plain-vanilla portfolio...... insurance largely died with the crash of 1987, but CPPI is still going strong. In the frictionless markets of finance theory, the issuer’s strategy to hedge its liability under the contract is clear, but in the real world with transactions costs and stochastic jump risk, the optimal strategy is less obvious...
Beiu, V.
1997-04-01
In this paper the authors discuss several complexity aspects pertaining to neural networks, commonly known as the curse of dimensionality. The focus will be on: (1) size complexity and depth-size tradeoffs; (2) complexity of learning; and (3) precision and limited interconnectivity. Results have been obtained for each of these problems when dealt with separately, but few things are known as to the links among them. They start by presenting known results and try to establish connections between them. These show that they are facing very difficult problems--exponential growth in either space (i.e. precision and size) and/or time (i.e., learning and depth)--when resorting to neural networks for solving general problems. The paper will present a solution for lowering some constants, by playing on the depth-size tradeoff.
Jackson Neal
2007-09-01
Full Text Available I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. In the last 20 years, much progress has been made and estimates now range between 60 and 75 km s^-1 Mpc^-1, with most now between 70 and 75 km s^-1 Mpc^-1, a huge improvement over the factor-of-2 uncertainty which used to prevail. Further improvements which gave a generally agreed margin of error of a few percent rather than the current 10% would be vital input to much other interesting cosmology. There are several programmes which are likely to lead us to this point in the next 10 years.
Decay constants in geochronology
IgorM.Villa; PaulR.Renne
2005-01-01
Geologic time is fundamental to the Earth Sciences, and progress in many disciplines depends critically on our ability to measure time with increasing accuracy and precision. Isotopic geochronology makes use of the decay of radioactive nuclides as a help to quantify the histories of rock, minerals, and other materials. Both accuracy and precision of radioisotopic ages are, at present, limited by those of radioactive decay constants. Modem mass spectrometers can measure isotope ratios with a precision of 10-4 or better. On the other hand, the uncertainties associated with direct half-life determinations are, in most cases, still at the percent level. The present short note briefly summarizes progress and problems that have been encountered during the Working Group's activity.
Lokajová, Jana; Railila, A.; King, A. W. T.; Wiedmer, S. K.
2013-01-01
Roč. 1308, Sep 20 (2013), s. 144-151. ISSN 0021-9673 R&D Projects: GA TA ČR TA02010760 Institutional support: RVO:61388963 Keywords : critical micelle concentration * electrokinetic chromatography * distribution constant * PeakMaster * phosphonium ionic liquid Subject RIV: CC - Organic Chemistry Impact factor: 4.258, year: 2013
Bubble Universes With Different Gravitational Constants
Takamizu, Yu-ichi
2015-01-01
We argue a scenario motivated by the context of string landscape, where our universe is produced by a new vacuum bubble embedded in an old bubble and these bubble universes have not only different cosmological constants, but also their own different gravitational constants. We study these effects on the primordial curvature perturbations. In order to construct a model of varying gravitational constants, we use the Jordan-Brans-Dicke (JBD) theory where different expectation values of scalar fields produce difference of constants. In this system, we investigate the nucleation of bubble universe and dynamics of the wall separating two spacetimes. In particular, the primordial curvature perturbation on superhorizon scales can be affected by the wall trajectory as the boundary effect. We show the effect of gravitational constant in the exterior bubble universe can provide a peak like a bump feature at a large scale in a modulation of power spectrum.
Martins José C; Hendrickx Pieter MS
2008-01-01
Abstract Background The advent of combinatorial chemistry has revived the interest in five-membered heterocyclic rings as scaffolds in pharmaceutical research. They are also the target of modifications in nucleic acid chemistry. Hence, the characterization of their conformational features is of considerable interest. This can be accomplished from the analysis of the 3JHH scalar coupling constants. Results A freely available program including an easy-to-use graphical user interface (GUI) has b...
The interacting and non-constant cosmological constant
We propose a time-varying cosmological constant with a fixed equation of state, which evolves mainly through its interaction with the background during most of the long history of the universe. However, such interaction does not exist in the very early and the late-time universe and produces the acceleration during these eras when it becomes very nearly a constant. It is found that after the initial inflationary phase, the cosmological constant, which we call as lambda parameter, rolls down from a large constant value to another but very small constant value and further dominates the present epoch showing up in the form of the dark energy driving the acceleration. (author)
Adelic Universe and Cosmological Constant
Makhaldiani, Nugzar
2003-01-01
In the quantum adelic field (string) theory models, vacuum energy -- cosmological constant vanish. The other (alternative ?) mechanism is given by supersymmetric theories. Some observations on prime numbers, zeta -- function and fine structure constant are also considered.
Dyes with high dielectric constants
Langhals, Heinz
1988-01-01
The dielectric constants of perylene dyes, perylene-3,4: 9,10-tetracarboxylic bisimides, are reported. With aromatic substituents, dielectric constants up to 110 are obtained. With polymeric dyes, the dielectric constants rise to 260. Mechanisms and applications are discussed.
Santos, Cesar A.G.; Correa, Jorge E. [Para Univ., Belem (Brazil). Centro Tecnologico. Dept. de Engenharia Mecanica]. E-mails: gsantos@ufpa.br; jecorrea@amazon.com.br
2000-07-01
This work performs a comparative analysis among the constant and variable air volume multi zones acclimation systems, used for provide the thermal comfort in buildings. The work used the simulation HVAC2KIT computer program. The results of sensible and latent heats transfer rates on the cooling and dehumidification, inflating fan capacity, and heat transfer on the final heating condenser were obtained and analysed for the climate conditions of the Brazilian city of Belem from Para State, presenting hot and humid climate during all the year.
Cleaning up the cosmological constant
Kimpton, Ian
2012-01-01
We present a novel idea for screening the vacuum energy contribution to the overall value of the cosmological constant, thereby enabling us to choose the bare value of the vacuum curvature empirically, without any need to worry about the zero-point energy contributions of each particle. The trick is to couple matter to a metric that is really a composite of other fields, with the property that the square-root of its determinant is the integrand of a topological invariant, and/or a total derivative. This ensures that the vacuum energy contribution to the Lagrangian is non-dynamical. We then give an explicit example of a theory with this property that is free from Ostrogradski ghosts, and is consistent with solar system physics and cosmological tests.
ELENA ANGHEL
2011-04-01
Full Text Available "Are we watching, in the succession of history, the appearance and disappearance of legal systems or assisting, in a greater or lesser extent, to what might be considered, in a sense, an evolution of those systems?"1 Law, indissolubly linked to the general evolution of society, has recorded a number of differences in time and space, both in terms of content of various types and positive law systems, and also in terms of forms that take the rules of law, authorities who have the ability to edict it or the procedure to be followed.Indeed, there is no law for all times and all places, as law is not an abstract product of our reason, it comes from the human experience, it is a product of history and that is why institutions of each society can only be different from one society to another.2 But, as in reality there are not quantities of history - many, little or very little - but just history3, we can say that in typology there is not socialist law absolutely different from bourgeois, feudal or slave law, so there is just law. By this approach, I wanted to bring back into question the existence of some factors of constancy in law, those "legal permanencies” investigated by Edmond Picard, believing that "there is something in the legal relationship that necessarily subsist anywhere”.4
Selby, David; Creaser, Robert A.; Stein, Holly J.; Markey, Richard J.; Hannah, Judith L.
2007-04-01
The past decade has seen renewed interest in 187Re- 187Os geochronology using a variety of matrices including sulfide minerals, shales and meteorites. The most widely used value of the 187Re decay constant ( λ187Re) is 1.666 ± 0.005 × 10 -11 a -1 (±0.31%), which is based on cross calibration of Re-Os and Pb-Pb chronometers for certain meteorites [Smoliar M. I., Walker R. J., and Morgan J. W. (1996) Re-Os isotope constraints on the age of Group IIA, IIIA, IVA, and IVB iron meteorites. Science271, 1099-1102]. However, other recent studies have yielded alternate values of λ187Re, based upon either direct counting experiments or analysis of meteorites. Here, we provide an independent assessment of λ187Re, using methodology, sample materials, and preparation of Os standard solutions different from those of Smoliar et al. (1996). Combining Re-Os age data for molybdenite formed in magmatic ore deposits, with the U-Pb zircon age of the magmatic rocks, a refined λ187Re value is determined by averaging 11 individual cross-calibration experiments spanning ca. 2700 Ma of Earth history. Using the U decay constants of Jaffey [Jaffey A. H., Flynn K. F., Glendenin L. E., Bentley W. C., and Essling A. M. (1971) Precision measurement of half-lives and specific activities of 235U and 238U. Phys. Rev.4, 1889-1906], a value for λ187Re of 1.6668 ± 0.0034 × 10 -11 a -1 is determined. Using the λ238U value of Jaffey et al. (1971) and λ235U value of Schoene [Schoene B., Crowley J. L., Condon D. J., Schmitz M. D., and Bowring S. A. (2006) Reassessing the uranium decay constants for geochronology using ID-TIMS U-Pb data. Geochim. Cosmochim. Acta70, 426-445], a value for λ187Re of 1.6689 ± 0.0031 × 10 -11 a -1 is determined. These values are nominally higher (ca. 0.1 and ca. 0.2%) than the value determined by Smoliar et al. [Smoliar M. I., Walker R. J., and Morgan J. W. (1996) Re-Os isotope constraints on the age of Group IIA, IIIA, IVA, and IVB iron meteorites. Science271
Forward recursions and normalizing constant
Guyon, Xavier; Hardouin, Cécile
2009-01-01
Maximum likelihood parameter estimation is frequently replaced by various techniques because of its intractable normalizing constant. In the same way, the literature displays various alternatives for distributions involving such unreachable constants. In this paper, we consider a Gibbs distribution $\\pi $ and present a recurrence formula allowing a recursive calculus of the marginals of $\\pi $ and in the same time its normalizing constant$.$ The numerical performance of this algorithm is eval...
Basic constant of matter world
It was analysed how to gain constant 46 hidden among elementary units of matter world, which is divided into, 1, 2, 4, 8, 16, 8, 4, 2, 1. Here it shows the unity of opposites on philosophy and simple symmetric beauty of mathphysics. The constant specifically shows that scope constant 44 in nuclides layer of matter world and chromosome number of mankind is 23 pairs, which is the highest form of matter motion, the basic cause of existing constant 46 is that matter exists in space-time with 4-dimensions, and it obeys the principle of the most lower energy
Diaz S, A.; Fuentes C, P.; Merino C, F. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)], e-mail: angeles.diaz@inin.gob.mx
2009-10-15
Whit the objective of to complete the existent techniques for susceptibility evaluation to phenomenon of stress corrosion cracking in laboratories of Applied Sciences Area of National Institute of Nuclear Research; was realized and documented the modification of a high pressure and temperature equipment, identified as MEX-03 to carry out the implementation of a growth and crack propagation assay, using a constant load method. The assay was realized to a specimen of stainless steel AISI 304l type CT of an inch, which was previously thermally sensitize, simulating the typical degradation of this materials type below operation conditions in a BWR. The MEX-03 system, consist from an annexed auto key to a load system which originally was controlled by displacement; therefore were carried out modifications to achieve the control by load. The realized adjustments allowed to maintain a constant load during all the experiment, and as much the temperature conditions (T = 288 C) as of pressure (P = 8 Mpa) were controlled during the assay realization. The steel was exposed to a conditioned ambient with hydrogen gas addition; simulating a well-known alternative chemistry as hydrogen water chemistry that is used to mitigate the phenomenon of stress corrosion cracking, main degradation mechanism of austenitic stainless steels. The continuation of the crack behavior was realized by means of electric potential fall technique and later was validated of visual form through the fractographic analysis of cracked surface. The modification and control of equipment for realization of this experiment is necessary, for what should be carried out new assays, whose results will allow to establish the effect of dynamic and static methods in velocity determination of crack growth to laboratory level; to be considered in the existent models of crack propagation in systems and components in operation. (Author)
Spectrophotometric determination of association constant
Spanget-Larsen, Jens
2016-01-01
Least-squares 'Systematic Trial-and-Error Procedure' (STEP) for spectrophotometric evaluation of association constant (equilibrium constant) K and molar absorption coefficient E for a 1:1 molecular complex, A + B = C, with error analysis according to Conrow et al. (1964). An analysis of the Charg...
Formulas for determining rotational constants
Guelachvili, G.
This document is part of Subvolume B `Linear Triatomic Molecules', Part 9, of Volume 20 `Molecular Constants mostly from Infrared Spectroscopy' of Landolt-Börnstein Group II `Molecules and Radicals'. Part of the introduction, it states formulas for determining rotational constants, band center, band origin, and quadrupole coupling. Specific comments relate to BHO (HBO) and COS (OCS).
The stability of fundamental constants
The tests of the constancy of fundamental constants are tests of the local position invariance and thus of the equivalence principle, at the heart of general relativity. After summarising the links between fundamental constants, gravity, cosmology and metrology, a brief overview of the observational and experimental constraints on their variation is proposed. (authors)
Gaudray, Gordon
2015-01-01
Remote hybrid power systems (RHPS) serve local off-grid loads or various island grids when no grid extension is possible. They combine renewable resources, conventional generators and energy storage systems in order to balance the load at any moment, while ensuring power quality and energy security similar to large centralized grids. Modelling such a complex system is crucial for carrying out proper simulations for predicting the system’s behavior and for optimal sizing of components. The mod...
Orlando Ragnisco
2010-12-01
Full Text Available A novel family of exactly solvable quantum systems on curved space is presented. The family is the quantum version of the classical Perlick family, which comprises all maximally superintegrable 3-dimensional Hamiltonian systems with spherical symmetry. The high number of symmetries (both geometrical and dynamical exhibited by the classical systems has a counterpart in the accidental degeneracy in the spectrum of the quantum systems. This family of quantum problem is completely solved with the techniques of the SUSYQM (supersymmetric quantum mechanics. We also analyze in detail the ordering problem arising in the quantization of the kinetic term of the classical Hamiltonian, stressing the link existing between two physically meaningful quantizations: the geometrical quantization and the position dependent mass quantization.
Belyaev Valeriy L’vovich
2016-02-01
Full Text Available The concept of a geoinformation system for urban geoenvironment is concerned. Geological data is necessary for the sustainable development of city infrastructure. The municipal departments should use geological and environmental information for perspective planning, selecting the location for important infrastructure objects, solving ecologycal problems, and in decision making. The concept includes a preliminary list of system’s users, their informational needs, main functionalities, methodical approaches to the system design and development. Geological data must contain source documents from geological archives “as is” and geodata based on its interpretation for various tasks. These data must be checked carefully and updated with new engineering-geological investigations. Geoinformation system must integrate various geological, engineering-geological, hydrogeological, and environmental data. Sophisticated procedures must be provided to check complicated logical dependences in the system database and to analyze contradictions between source documents. 3D modeling is an adequate language for presenting geological data, therefore, the considered system must include 3D models of various scales. In the suggested concept 3D modeling is considered as a tool for investigations, not only for presentations. The end users should have possibilities to get results of their queries in various formats: tables, geological and thematic maps, geological cross-sections, 2D and 3D grids as source data for mathematical modeling, etc. In conclusion, the paper briefly describes IEG RAS activities in GIS technologies for geological cartography and 3D modeling.
Symmetries and constant mean curvature surfaces
In this paper, we discuss the Lie symmetries, symmetry algebra and symmetry reductions of the equation which describes constant mean curvature surfaces via the generalized Weierstrass-Enneper formulae. First we point out that the equation admits an infinite-dimensional symmetry Lie algebra. Then using symmetry reductions, we obtain two integrable Hamiltonian systems (one autonomous, the other nonautonomous) with two degrees of freedom. The autonomous one was obtained by Konopelchenko and Taimanov by other means. Our method provides a new approach for construction of constant mean curvature surfaces. (author)
A new, completely rewritten version of the FEDGROUP program system is presented in this report. The formulae and the algorithm underlying the calculation are revised. The FEDGROUP-3 is able to calculate group averaged infinite diluted and screened cross-sections, elastic and inelastic transfer matrices, point-wise cross-section sets from evaluated data in ENDF/B, KEDAK and UKNDL format. The program system is written mainly in FORTRAN-IV of IBM-OS but it can be adapted relatively easily to other type of computers. (author)
Constant Communities in Complex Networks
Chakraborty, Tanmoy; Ganguly, Niloy; Bhowmick, Sanjukta; Mukherjee, Animesh
2013-01-01
Identifying community structure is a fundamental problem in network analysis. Most community detection algorithms are based on optimizing a combinatorial parameter, for example modularity. This optimization is generally NP-hard, thus merely changing the vertex order can alter their assignments to the community. However, there has been very less study on how vertex ordering influences the results of the community detection algorithms. Here we identify and study the properties of invariant groups of vertices (constant communities) whose assignment to communities are, quite remarkably, not affected by vertex ordering. The percentage of constant communities can vary across different applications and based on empirical results we propose metrics to evaluate these communities. Using constant communities as a pre-processing step, one can significantly reduce the variation of the results. Finally, we present a case study on phoneme network and illustrate that constant communities, quite strikingly, form the core func...
Fundamental Constants and Conservation Laws
Roh, Heui-Seol
2001-01-01
This work describes underlying features of the universe such as fundamental constants and cosmological parameters, conservation laws, baryon and lepton asymmetries, etc. in the context of local gauge theories for fundamental forces under the constraint of the flat universe. Conservation laws for fundamental forces are related to gauge theories for fundamental forces, their resulting fundamental constants are quantitatively analyzed, and their possible violations at different energy scales are...
Rotating spacetimes with a cosmological constant
We develop solution-generating techniques for stationary metrics with one angular momentum and axial symmetry, in the presence of a cosmological constant and in arbitrary spacetime dimension. In parallel we study the related lower dimensional Einstein-Maxwell-dilaton static spacetimes with a Liouville potential. For vanishing cosmological constant, we show that the field equations in more than four dimensions decouple into a four dimensional Papapetrou system and a Weyl system. We also show that given any four dimensional 'seed' solution, one can construct an infinity of higher dimensional solutions parametrised by the Weyl potentials, associated to the extra dimensions. When the cosmological constant is non-zero, we discuss the symmetries of the field equations, and then extend the well known works of Papapetrou and Ernst (concerning the complex Ernst equation) in four-dimensional general relativity, to arbitrary dimensions. In particular, we demonstrate that the Papapetrou hypothesis generically reduces a stationary system to a static one even in the presence of a cosmological constant. We also give a particular class of solutions which are deformations of the (planar) adS soliton and the (planar) adS black hole. We give example solutions of these techniques and determine the four-dimensional seed solutions of the 5 dimensional black ring and the Myers-Perry black hole
Rathore Umesh C.
2016-01-01
Full Text Available This paper presents the experimental evaluation of the performance of 3-φ self-excited induction generator (SEIG suitable for pico-hydro power generation system feeding domestic load in remote mountainous region. The use of induction generators is most suitable for renewable energy conversion systems due to their enormous advantages over conventional synchronous generators. Important features of induction generators include the simplicity in construction, ruggedness, simplified control, ease in maintenance and small size per generated kW. The performance characteristics of 3-φ SEIG feeding isolated load are evaluated using MATLAB-Simulink model based on the prevalent renewable energy sources inputs and loading conditions in mountainous terrain of Himalayas. The results are validated using an experimental set-up comprising of 3-φ, 3 HP induction motor run as 3- φ induction generator driven by 5HP, 4-pole DC shunt motor acting as prime-mover.
From the Rydberg constant to the fundamental constants metrology
This document reviews the theoretical and experimental achievements of the author since the beginning of his scientific career. This document is dedicated to the spectroscopy of hydrogen, deuterium and helium atoms. The first part is divided into 6 sub-sections: 1) the principles of hydrogen spectroscopy, 2) the measurement of the 2S-nS/nD transitions, 3) other optical frequency measurements, 4) our contribution to the determination of the Rydberg constant, 5) our current experiment on the 1S-3S transition, 6) the spectroscopy of the muonic hydrogen. Our experiments have improved the accuracy of the Rydberg Constant by a factor 25 in 15 years and we have achieved the first absolute optical frequency measurement of a transition in hydrogen. The second part is dedicated to the measurement of the fine structure constant and the last part deals with helium spectroscopy and the search for optical references in the near infrared range. (A.C.)
Benard, P; Vivoda, J; Smolikova, P; Benard, Pierre; Laprise, Rene; Vivoda, Jozef; Smolikova, Petra
2003-01-01
The aim of this paper is to investigate the response of this system/scheme in terms of stability in presence of explicitly treated residual terms, as it inevitably occurs in the reality of NWP. This sudy is restricted to the impact of thermal and baric residual terms (metric residual terms linked to the orography are not considered here). It is shown that conversely to what occurs with Hydrostatic Primitive Equations, the choice of the prognostic variables used to solve the system in time is of primary importance for the robustness with Euler Equations. For an optimal choice of prognostic variables, unconditionnally stable schemes can be obtained (with respect to the length of the time-step), but only for a smaller range of reference states than in the case of Hydrostatic Primitive Equations. This study also indicates that: (i) vertical coordinates based on geometrical height and on mass behave similarly in terms of stability for the problems examined here, and (ii) hybrid coordinates induce an intrinsic inst...