共查询到20条相似文献，搜索用时 515 毫秒
1.
Xiang-wen Chen Hui-zhen Li Gui-qing Li Ling Qin Zhi-fang Zhang 《International Journal of Infrared and Millimeter Waves》1994,15(9):1555-1566
This paper presents a theoretical method for design quasi-optics power combiner of solid-state millimeter — wave sources, and gives theory analysis to some problem concerned. Here is the structure:
相似文献
| 1. | Epitome of microwave power combiner. |
| 2. | Gauss light beam and the field distribution in the resonator. |
| 3. | The design of the resonator |
| (1) | Confocal resonator |
| (2) | Objective function |
| (3) | The global optimization method and the program flow chart. |
| 4. | Example |
| 5. | Reference |
2.
From our experiments the following conclusions follow:
相似文献
| i) | The value of a in the l/f a law lies within the intervala (0.6, 1.0). |
| ii) | The detectors featuring low reverse currentI c havea 1.0. |
| iii) | The cutoff frequency of the noise characteristicf c is at low frequency compared with the using frequency band of the detector. |
| iv) | The excess noise is given by generation-recombination process in the volume of the space — charge region of the sample. |
3.
E. Bodenstedt 《Hyperfine Interactions》1976,2(1):1-14
In this talk the discussion of nuclear physics studied by hyperfine methods is limited to a few topics of high actuality:
相似文献
| (a) | Isomer shift data for 2+ rotational states gave r/r values much smaller than predicted by the simple centrifugal stretching model. They provide evidence for a strong Coriolis anti-pairing effect as recent detailed microscopic calculations show. |
| (b) | The Coriolis force causes also the famous back-bending effect at high rotational angular momenta. This phenomenon is not yet really understood. MeasuredgR values in this region would be very informative. The present situation of this challenging task is discussed. |
| (c) | Precisely measured magnetic dipole moments of high-spin few-particle states allow in favourable cases the derivation of the meson exchange contribution. The general situation and new results are reported. |
| (d) | Quite a few electric quadrupole moments of high spin states of several tin isotopes have recently been measured. The discussion in terms of the simple shell model reveals already interesting features. Especially the subshell filling effect is nicely exhibited. |
4.
M. V. Gorbatenko 《General Relativity and Gravitation》2005,37(1):81-98
New possibilities in the solution to the general relativity problems appearing in the conformally invariant generalization of Einsteins equations are addressed. The conformally invariant equations and their solutions possess the following properties:
The paper briefly describes these properties and discusses possible methods to use them for the solution of general relativity problems. 相似文献
| 1. | The Cauchy problem is posed without any constraints on the Cauchy data. |
| 2. | Solutions with discontinuities on space-like hypersurfaces are admitted. |
| 3. | A conserved current vector appears. |
| 4. | A new function of state similar to entropy appears. |
| 5. | The gauge vector and the lambda term can be interpreted in terms of degrees of freedom of 1/2-spin particles. |
5.
| 1. | The method for solving the reconstruction problem proposed here makes it possible to use physically grounded a priori information which is reliable for many radio-astronomy problems. |
| 2. | The method reduces the incorrectly formulated problem of reconstructing the nonnegative curve to a correctly formulated problem of reconstructing a monotonic curve. The numerical-differentiation operation remains incorrect; this operation is comparatively simple to carry out. |
| 3. | It is possible to incorporate in the numerical differentiation and the solution of the mathematical-programming problems additional a priori information, whose nature is determined in each particular case. |
| 4. | The solution of the reconstruction problem reduces to the application of numerical-analysis methods which have been worked out thoroughly, and there are no fundamental difficulties involved here. |
6.
ForG a classical group, an equivalence is exhibited between:
A) and B) are linked by twistor techniques, B) and C) via the Krichever method for solving non-linear differential equations, and A) and C) via the ADHMN construction, providing a unified picture of techniques for solution. Amongst other things, an asymptotic formula for the Higgs field of the monopole is computed.Communicated by A. Jaffe 相似文献
| A) | G monopoles over 3, with maximal symmetry breaking at infinity, |
| B) | families of (rank (G)) algebraic curves inT1, along with divisors on those curves, satisfying certain constraints, |
| C) | solutions of Nahm's equations over (rank(G)) intervals, satisfying the appropriate boundary conditions. |
7.
Luiz C. L. Botelho 《International Journal of Theoretical Physics》2009,48(6):1701-1711
In this paper we intend to present some path-integral studies in the problem of confinement in the presence of fermionic and
scalar magnetic monopole fields through:
相似文献
| 1. | A Wilson Loop Path-Integral Evaluation associated to an effective second-quantized electromagnetic field generated by chiral abelian point-like monopole magnetic field current. |
| 2. | A Path-Integral Bosonization analysis of Quarks fields interacting with Kalb-Ramond fields considered as an effective Disorder Field Theory of a Q.C.D. vacuum of heavier monopoles. |
| 3. | Improvements on the Wilson Loops evaluations in the well-known ADHM Antonov-Ebert model for Cooper pairs of point-like fermionic magnetic monopoles. |
8.
M. Malinowski R. Wolski Z. Frukacz T. Lukasiewicz Z. Luczynski 《Journal of Applied Spectroscopy》1995,62(5):840-843
Optical properties of the Sm3+ ion in YAG crystals have been investigated, in particular:
The relatively large emission cross section and long fluorescence lifetime enable red laser action to be obtained. 相似文献
| – | - the energy level diagram of Sm:YAG has been established. |
| – | - the emission characteristics of the metastable state4G5/2 have been determined. |
| – | - the oscillator strengths of various Sm transitions have been investigated using the Judd-Ofelt theory. |
9.
Wagendristel A. Tschegg E. Semerad E. Bangert H. 《Applied Physics A: Materials Science & Processing》1976,10(3):237-243
Computer simulation of superimposed lattice, grain boundary and surface diffusion, characteristic for polycrystalline thin
film diffusion systems, was performed by way of discretisation of the nonlinear diffusion law. In order to give a vivid impression
how such a complex process takes place under some typical conditions we have chosen pseudo three-dimensional computer plots
of the spacial distribution of the concentration instead of the commonly used iso-concentration diagrams. The following cases
are considered:
相似文献
| a) | Polycristal — single crystal couple with highly diffusive grain boundaries and surfaces, grain boundaries and interface, grain boundaries, surfaces and interface. |
| b) | Polycrystal — polycrystal couple with different displaced grain boundaries as well as different diffusivity ratios for the bulk and the highly conducting regions. |
10.
Francesco Caravenna Giambattista Giacomin Massimiliano Gubinelli 《Journal of statistical physics》2006,122(4):799-832
We consider a model of a random copolymer at a selective interface which undergoes a localization/delocalization transition. In spite of the several rigorous results available for this model,
the theoretical characterization of the phase transition has remained elusive and there is still no agreement about several
important issues, for example the behavior of the polymer near the phase transition line. From a rigorous viewpoint non coinciding
upper and lower bounds on the critical line are known.
In this paper we combine numerical computations with rigorous arguments to get to a better understanding of the phase diagram.
Our main results include:
2000 MSC: 60K37, 82B44, 82B80 相似文献
| – | Various numerical observations that suggest that the critical line lies strictly in between the two bounds. |
| – | A rigorous statistical test based on concentration inequalities and super–additivity, for determining whether a given point of the phase diagram is in the localized phase. This is applied in particular to show that, with a very low level of error, the lower bound does not coincide with the critical line. |
| – | An analysis of the precise asymptotic behavior of the partition function in the delocalized phase, with particular attention to the effect of rare atypical stretches in the disorder sequence and on whether or not in the delocalized regime the polymer path has a Brownian scaling. |
| – | A new proof of the lower bound on the critical line. This proof relies on a characterization of the localized regime which is more appealing for interpreting the numerical data. |
11.
| 1. | The intensities of hypersensitive transitions at 293 K increase with decreasing Ln−O bond length in both praseodymium and europium complexes. The intensity increase can also be caused, for praseodymium crystals, by lower energy of f-d transition bands. |
| 2. | The temperature dependence of the3H4→3Po transition for Pr(CF3COO)3·3H2O crystal probably indicates a phase transformation occurring at about 50 K. |
| 3. | The electronic lines are accompanied be weak vibronic components for transitions that obey the selection rules †J=0,2. |
| 4. | The intensities of vibronic sidebands in excitation spectra are stronger than those in emission ones for europium single crystals at 77 K. |
| 5. | Lowering of the energy of f-d bands is observed in the crystals in the order Pr(CCl3COO)3<Pr(CF3COO)3, what can affect the vibronic coupling more strongly in the former case. |
| 6. | The relative-intensity relation for the two types of europium crystal (I and II) indicate stronger distortion of coordination polyhedra in trifluoroacetate crystals. |
| 7. | The number of components of the5Do→7FJ transition indicates the existence of two symmetry centers of the Eu3+ ion in trichloroacetate, thus confirming results obtained by the X-ray method. |
12.
Valter Moretti 《Communications in Mathematical Physics》2008,279(1):31-75
This paper continues the analysis of the quantum states introduced in previous works and determined by the universal asymptotic
structure of four-dimensional asymptotically flat vacuum spacetimes at null infinity M. It is now focused on the quantum state λ
M
, of a massless conformally coupled scalar field propagating in M. λ
M
is “holographically” induced in the bulk by the universal BMS-invariant state λ defined on the future null infinity of M. It is done by means of the correspondence between observables in the bulk and those on the boundary at future null infinity
discussed in previous papers. This induction is possible when some requirements are fulfilled, in particular whenever the
spacetime M and the associated unphysical one, M͂, are globally hyperbolic and M admits future time infinity i
+. λ
M
coincides with Minkowski vacuum if M is Minkowski spacetime. It is now proved that, in the general case of a curved spacetime M, the state λ
M
enjoys the following further remarkable properties:
相似文献
| (i) | λ M is invariant under the (unit component of the Lie) group of isometries of the bulk spacetime M. |
| (ii) | λ M fulfills a natural energy-positivity condition with respect to every notion of Killing time (if any) in the bulk spacetime M: If M admits a time-like Killing vector, the associated one-parameter group of isometries is represented by a strongly-continuous unitary group in the GNS representation of λ M . The unitary group has positive self-adjoint generator without zero modes in the one-particle space. In this case λ M is a so-called regular ground state. |
| (iii) | λ M is (globally) Hadamard in M and thus it can be used as the starting point for the perturbative renormalisation procedure of QFT of in M. |
13.
14.
Recently, folk questions on the smoothability of Cauchy hypersurfaces and time functions of a globally hyperbolic spacetime M, have been solved. Here we give further results, applicable to several problems:
Even more, accurate versions of this last result are obtained if the Cauchy hypersurface S were non-spacelike (including non-smooth, or achronal but non-acausal). 相似文献
| (1) | Any compact spacelike acausal submanifold H with boundary can be extended to a spacelike Cauchy hypersurface S. If H were only achronal, counterexamples to the smooth extension exist, but a continuous extension (in fact, valid for any compact achronal subset K) is still possible. |
| (2) | Given any spacelike Cauchy hypersurface S, a Cauchy temporal function (i.e., a smooth function with past-directed timelike gradient everywhere, and Cauchy hypersurfaces as levels) with is constructed – thus, the spacetime splits orthogonally as in a canonical way. |
15.
Our results lead to the following conclusions.
The authors are grateful to O. Ipat’eva, A. Kokh, and A. Yurkin of the “Single-Crystal” Collective Technica Institute for
supplying the high-quality high-voltage equipment elements. 相似文献
| 1. | A CVL with a nonlinear frequency converter can be regarded as a source of high-power UV radiation discretel tunable in three wavelengths. |
| 2. | The presence of the CVL beam of a low-coherence (single-pass) radiation is one of the main factors that limi the efficiency of the nonlinear conversion. |
16.
We study the radial motion along null geodesics in the Reissner-Nordström-de Sitter and Kerr-de Sitter space-times. We analyze the properties of the effective potential and we discuss circular orbits. We find that:
相似文献
| 1) | the radius of circular photon orbits in the Reissner-Nordström-de Sitter space-times does not depend on the cosmological constant. We show also how this is related to properties of the optical reference geometry. |
| 2) | For a specific range of the cosmological constant, photons with high impact parameter may travel radially between the cosmological horizon and the black hole horizon in the equatorial plane of the Kerr-de Sitter space-times. |
17.
L. P. Kamburov H. D. Hristov J. R. Urumov R. Feick 《International Journal of Infrared and Millimeter Waves》2005,26(11):1593-1611
A generalized vector diffraction theory of the half-open curvilinear Fresnel zone plate (FZP) tens antenna that is valid for
any lens profile shape is presented. It is an extension to the vector Kirchhoff diffraction theory for the plane half-open
FZP lens antenna and is based on the conical-segment lens profile approximation. An equation for the electric far-field vector
is derived from which follow the expressions for the co- and cross-polarization radiation patterns and directive gain. The
proposed theory is utilized for a numerical analysis and comparison of 140-GHz curvilinear half-open FZP lens antennas grouped
in two distinct sets:
相似文献
| (a) | Set I: antennas with different in shape FZP lenses (plane, conical, parabolic and spherical) having the same number of zones. All eurvilinear FZP antenna lenses are designed for similar gain, co- and cross-polarization performance and bandwidth, regardless of the lens-profile. |
| (b) | Set II: antennas with different in shape FZP lenses and different number of zones. Since this affects gain, polarization and bandwidth performance, to make the characteristics of these FZP lens antennas practically equal to those of Set I, antenna feeds with different gain patterns have been used. |
18.
We have developed a sequential radiochemical separation method (SRCS) in order to isolate each trans-uranium element (TRU)
contained in a TRU target (or fuel) irradiated in the experimental fast reactor JOYO.
The chemical separation procedures for SRCS consist of the following steps:
The SRCS flow sheet was applied to the analyses of MOX fuels irradiated in the experimental fast reactor JOYO. On the basis
of isotope analysis, the transmutation and incineration behaviour of trans-uranium nuclides were elucidated. The transmutation
ratios of irradiated two TRU targets were evaluated and ranged from 8.05 to 10.79 % in this study. 相似文献
| 1 | Target dissolution with an 8 M (mol/dm3) of HNO3 solution including hydrogen peroxides as a valence control reagent for Pu and Np to their tetravalent states. |
| 2 | Sequential elution of fission products (FP’s) including trivalent actinides (An(III)) and lanthanides (Ln(III)), U(VI), Pu(III), and Np(IV) from an anion exchange resin column. The decontamination factor (DF) of Pu(III) in the Np(IV) was much higher than 106. |
| 3 | Group separation for Ln(III) and An(III). The DF of Ln(III) for the separated An(III) exceeds 5×103 and that of Am and Cm for the separated An(III)-fraction exceeds 104. |
| 4 | Mutual separation of Am(III) and Cm(III), also for each lanthanide. |
19.
A. Kozanecki 《Journal of Applied Spectroscopy》1995,62(4):731-741
RBS/channeling investigations of Yb-, Nd-, and Er-doped III–V compounds and silicon revealed some regularities in the behavior
of RE atoms:
Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warshawa, Poland. Published in Zhurnal Prikladnoi
Spektroskopii, Vol. 62, No. 5, pp. 145–157, July–August, 1995. 相似文献
| 1. | Nonsubstitutional location of RE atoms seems to be a common rule in zincblende structure semiconductors. An exception is the case of Yb in InP and InP-based compounds. |
| 2. | Recrystallization of the layers amorphized by implantation of RE ions at room temperature is never complete, due to the presence of RE atoms in the layers. The implanted RE atoms segregate at the surface during thermal annealing. Implantation at elevated temperatures prevents amorphization and out-diffusion of REs. |
| 3. | Nonsubstitutional locaton of Er in silicon has been well documented here by measurements of RBS/channeling spectra (Figs. 9a and 9b) and angular scan profiles as well (Figs. 11a and 11b). Careful consideration of all the experimental data allows us to conclude that the implanted Er atoms locate close to hexagonal interstitial lattice sites. This tentative conclusion will be tested in the near future by model simulations. |
20.
A. Benninghoven D. Jaspers W. Sichtermann 《Applied Physics A: Materials Science & Processing》1976,11(1):35-39
Secondary-ion mass spectroscopy (SIMS) is a hydrogen, isotope and compound sensitive analytical technique of extremely high
absolute sensitivity. Continuing earlier measurements for carboxylic acids, adsorbed alcohols etc., we have carried out a
systematical investigation of secondary-ion emission from metal-supported amino acids, containing various functional groups
(e.g., alanine, phenylalanine, cysteine, arginine). In order to avoid damage effects we applied extremely small primary-ion
current densities in the 10−9 A·cm−2 range.
The main results of our investigations can be summarized as follows:
相似文献
| – | - All investigated amino acids produce high-intensity secondary-ion parent peaks (M+1)+ and (M−1)−. |
| – | - In addition positive as well as negative fragment ions representative for the different functional groups are emitted with high yields. |
| – | - For 2.5 keV Ar+-ions the absolute yields for the parent ions and the most important fragment ions are in the range of 0.1; the damage cross section is >10−14 cm2 for all investigated acids. The resulting absolute sensitivities are below 10−6 of one monomolecular layer or <10−12 g. |