On several concepts for ɛ-efficiency

We introduce two new concepts for?-efficiency and investigate these and some known concepts under the following aspects: (1) What are the relationships between the efficient and the?-efficient point set? (2) If the sequence (v ^?) of?-efficient points converges forε → 0, is the limit efficient, or weakly efficient? (3) Can the distance between the?-efficient and the efficient point set be estimated in terms ofε?     

Maximizing pseudoconvex transportation problem: a special type

The paper discusses a non-concave fractional programming problem aiming at maximization of a pseudoconvex function under standard transportation conditions. The pseudoconvex function considered here is the product of two linear functions contrasted with a positive valued linear function. It has been established that optimal solution of the problem is attainable at an extreme point of the convex feasible region. The problem is shown to be related to indefinite quadratic programming which deals with maximization of a convex function over the given feasible region. It has been further established that the local maximum point of this quadratic programming problem is the global maximum point under certain conditions, and its optimal solution provides an upper bound on the optimal value of the main problem. The extreme point solutions of the indefinite quadratic program are ranked to tighten the bounds on the optimal value of the main problem and a convergent algorithm is developed to obtain the optimal solution.     

(Pre)kernel catchers for cooperative games

The paper provides a new (pre)kernel catcher in that the relevant set always contains the (pre)kernel. This new (pre)kernel catcher gives rise to a better lower bound _*** such that the kernel is included in strong -cores for all real numbers not smaller than the relevant bound _***.The research for this paper was done under the sponsorship of both the Dutch Organization for the Advancement of Scientific Research (NWO) and the National Science Council (NSC) of Taiwan during a stay of Dr. Chih Chang at the University of Twente, Enschede, The Netherlands.     

Novel methodology to investigate superconducting dielectric resonators

An analytical method is presented for investigating the resonant behavior of a c-axis oriented YBa₂Cu₂O_7–(0) thin film on a resonator composed of LaAlO₃ (001). The concept of the negative dielectric medium for a superconductor is introduced within the framework of the two-fluid model, which permits us to treat a superconductor as any other penetrable materials so that only its electromagnetics are concerned. A conformai transformation is further suggested to map the original open boundary-value problem to a closed one. This not only makes the original problem readily solvable by using the variational technique, but is also a powerful tool for analyzing some kinds of problems such as the propagation characteristics of the superconducting microstripe and coplanar waveguide structures.     

Density of α-pinene, Β-pinene,limonene, and essence of turpentine

Densities of ga-pinene, -pinene, limonene, and essence of turpentine have been measured at 293.15, 298.15, 303.15, 308.15, and 313.15 K, at atmospheric pressure, with a mechanical oscillator densimeter. Benzene and cyclohexane were used as calibration fluids. The precision is of the order of 0.01 kg · m^–3, while the accuracy is estimated to be 0.1%. A linear representation of the variation of the density with temperature reproduces the experimental data within 0.2%.     

Evolution of the Electronic Structure of Y-Bi-2212 from the Antiferromagnetic to the Superconducting Regime

The phase diagram of the cuprate superconductors at low doping and low temperatures in the non-superconducting state is dominated by magnetic correlations. When increasing the hole concentration in the CuO₂-planes from zero an antiferromagnetic (AF) insulating phase is followed for hole concentrations greater than approximately 0.08 by the superconducting phase. For the range of doping in between the situation is less clear and several models exist. For Bi₂Sr₂Y _x Ca_1–xCu₂O₈ in the range of Y-concentrations 0.9 < x < 0.0 the evolution of the electronic structure starting from the AF phase at x = 0.9, which in this respect can be regarded as the parent compound of the superconducting phase, and its gradual development into the superconducting range can be studied on one system. In this series the CuO₂-planes are kept embedded in a nearly identical environment for each hole concentration. Especially the results from the AF phase deviate from former reports attained mainly from oxychlorides.     

“Pseudogap” in High-Temperature Superconductors

It is shown that an existence of a pseudogap and peculiarities of its behavior under temperature and doping variation, both at doping above and below the optimal one, naturally follow from the impurity mechanism of high-temperature superconductivity, which is an additional argument in favor of it. Main attention is paid to the tunneling spectroscopy experimental data.     

Investition bei Unsicherheit als Erklärung für hohe implizite Diskontraten bei Energiesparinvestitionen

Zusammenfassung Die Tatsache, daß Konsumenten (und auch Unternehmen) hohe implizite Diskontraten bei der Entscheidung über Energiesparinvestitionen verwenden, wird häufig beobachtet. Dies wird fast einhellig als Marktversagen angesehen und hat viele Analytiker dazu veranlaßt, entweder für öffentliche oder bezuschußte Energiesparinvestitionen zu plädieren. In dieser Arbeit wird die Theorie der Realoptionen auf ein bekanntes Beispiel angewandt: der Wahl zwischen konventioneller Glühbirne und Sparlampe bei unterstellter Risikoneutralität des Entscheidungsträgers. Es zeigt sich, daß die dem Wert der Option des Abwartens und Aufschiebens der Investition Rechnung tragenden impliziten Diskontraten nahe den beobachteten Werten liegen. Deshalb bedarf die Schlußfolgerung eines Marktversagens aus hohen impliziten Diskontraten einer sorgfältigeren und feineren Analyse. Dies trifft a fortiori auf due Empfehlung von Energiesparprogrammen zu.Die Autoren sind zwei anonymen Gutachtern zu Dank für ihre konstruktiven Vorschläge verpflichtet     

The “Paramagnetic” Meissner Effect in Superconductors

There are a number of publications concerning the observation of a paramagnetic signal in HTSC ceramic samples during field-cooling procedures. Some authors assume that this signal is connected with spontaneous currents and discuss the possibility of the existence of -junctions in Josephson media. In this work, it is shown that the paramagnetic signal could appear in the case of capture and compression of the magnetic flux in a sample during field-cooling procedures. The results of numerical calculation of the magnetic moment for different configurations of the sample and flux compression are presented. The unusual behavior of longtime relaxation of the magnetic moment in experiments on capture of magnetic flux is discussed.     

Lambda-Calculus with Director Strings

We present a name free -calculus with explicit substitutions, based on a generalised notion of director strings. Terms are annotated with information – directors – that indicate how substitutions should be propagated. We first present a calculus where we can simulate arbitrary -reduction steps, and then simplify the rules to model the evaluation of functional programs (reduction to weak head normal form). We also show that we can define the closed reduction strategy. This is a weak strategy which, in contrast with standard weak strategies, allows certain reductions to take place inside -abstractions thus offering more sharing. Our experimental results confirm that, for large combinator-based terms, our weak evaluation strategies out-perform standard evaluators. Moreover, we derive two abstract machines for strong reduction which inherit the efficiency of the weak evaluators.Projet Logical, Pôle Commun de Recherche en Informatique du plateau de Saclay, CNRS, École Polytechnique, INRIA, Université Paris-Sud.     

Two holes in the finite Hubbard lattice with a strong magnetic field: The phase diagram

The Nagaoka instability and the existence of off-diagonal long-range order (ODLRO) and superconductivity for two holes near half-filling in 1d, 2d, and 3d hypercubes with periodic boundary conditions are exactly proven in the Hubbard model immersed in a strong magnetic field. The upper critical field and criteria for stability of either the spin-flipped or excitonic phases as a function of interaction strength are found. The theory predicts the possibility of the ODLRO mechanism of superconductivity in the strong-repulsion Hubbard model in arbitrary dimensions.     

Heat Inputs to Sub-mK Temperature Cryostats and Experiments from γ-Radiation and Cosmic Ray Muons

We measured the spectrum of energies deposited by -radiation, emanating from radioactive materials in the laboratory that houses our mK cryostat, and by cosmic ray muons. This allows us to quantify the heat input that adversely affects the lowest temperature accessible in sub-mK experiments. We use our nuclear stage, stage plate and experimental cell as a prototype model system, and calculate the power deposited due to low energy (below 2.65 MeV) background radiation quanta (~20 pW). This is significantly less than the power (~120 pW) deposited in the nuclear and experimental stages by muons. Installation of a 5 cm thick lead wall around the cryostat reduced the energy due to the flux of quanta by a factor of ~10 to ~2 pW, and the number of quanta by a factor of ~20. The lower energy, soft cosmic ray component was also affected by introducing the same thickness of lead, reducing the overall count of cosmic ray derived particles by ~15% and the heat leak to ~100 pW.     

The influence of the polarization of the radiation on the accuracy of the transmission of the dimensions of the unit of temperature in radiation thermometry

The results of an investigation of different types of tungsten lamps in order to estimate the components of the error budget of spectrum-pyrometer apparatus are presented. Quantitative relations are considered and the results of experimental research, which enable systematic methods to be developed for eliminating the influence of polarization of the radiation of the lamps in standard radiation thermometry, are analyzed.Translated from Izmeritelnaya Tekhnika, No. 9, pp. 42–45, September, 2004.     

Premelting transition in uranium dioxide

Thermal analysis of the cooling curves of small samples of UO_2±x —initially laser heated (in a high-pressure autoclave to inhibit evaporation) on a subsecond time scale to temperatures just below their melting points [T _m(x)]—reveals, in the case of nominally stoichiometric UO_2.00, a significant, -like, heat capacity [C _p(T)] peak near 2670 K; the cooling curves of samples exposed to a reducing environment, on the other hand, exhibit undercooling, characteristic of a first-order phase transition, while under oxidizing conditions it is found that the premelting transition readily disappears. These findings confirm Bredig's original prediction of a premelting transition in this material, in common with that found in other (nonactinide) fluorites near 0.85T _m. A simple model is presented in terms of which the observed behavior can be rationalized. The model is based on the hypothesis that the premelting transition is due to Frenkel disordering of the oxygen sublattice—a process which is rendered cooperative by attractive interactions between complementary Frenkel defects (oxygen interstitials and vacancies); these interactions are treated in a mean-field approximation. The quantitative degree of maximum disorder (realized just above the transition) is, on the other hand, controlled by repulsive interactions between like defects—the inclusion of which, solely through their effect on the configurational entropy, satisfactorily reproduces the values inferred from recent high-temperature neutron diffraction experiments. Assuming that the phase transition in stoichiometric UO_2.00 is of second order, the model predicts a divergent heat capacity, C _v, which approximates well to the experimental (-like) C _p peak. Crucial to reproducing the observed behavior away from stoichiometry is the introduction of a (linear) dependence of the nonconfigurational partial entropy of formation on the prevailing concentration of intrinsic Frenkel defects in UO_2±x; interestingly, it is found that the line of calculated (but unrealized) second-order transitions in UO_2+x intersects the U₄O₉ phase boundary near to where a high-temperature diffuse order-disorder transition has been observed in the oxygen superlattice, suggesting that the second-order, -transition in UO_2.00 is the stoichiometric counterpart of this transition in U₄O₉.     

A field astrogravigeodetic standard for metrological tests on geodetic equipment

The paper discusses the scope for a qualitatively new field standard with improved accuracy based on relative GPS/GLONASS satellite measurements, with the object of performing metrological tests on a wide range of geodesic instruments under realistic conditions.Translated from Izmeritelnaya Tekhnika, No. 9, pp. 3–7, September, 2004.     

Effects of measurement errors on sample monitoring reliability

Results are presented on the effects of measurement errors on items in routine production as regards the reliability of results on sampling inspection obtained by Monte Carlo simulation. The customers and the makers risks are examined in relation to the distributions of the measurement errors and the values of them.Translated from Izmeritelnaya Tekhnika, No. 12, pp. 8–11, December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Aluminum. II. Derivation of C v0from C p and comparison to C v0 calculated from anharmonic models

The specific heat at constant pressure, C _p, of aluminum measured by Ditmars, Plint, and Shukla has been reduced to the volume V ₀ appropriate for 0 K employing the Murnaghan equation. The C _v0 thus obtained is compared with the theoretical C _v0 calculated in the harmonic and the lowest-order anharmonic approximation from three different pseudopotentials (Harrison, Ashcroft, and Dagens-Rasolt-Taylor) as well as a phenomenological Morse potential. The higher-order ( ⁴) anharmonic contributions are calculated from the same nearest-neighbor Morse potential as in the lowest-order anharmonic theory. The role of the vacancy and the higher-order anharmonic contributions to C _v0 has been examined and we conclude that the ⁴ contributions to C _v0 are much smaller than the vacancy contribution. After removal of the vacancy contribution, the reduced C _v0 is found to be in excellent agreement with the Ashcroft and Harrison pseudopotentials as well as the Morse potential including the ² and ⁴ contributions to C _v0.     

New high-pressure Sr-Ca-Cu-O compounds and their superconducting properties

It is shown for (Sr, Ca)_1–y CuO_2.00+z (nominal composition) superconductors fabricated under a high pressure of 5 GPa and at 930°C that, as z increases, the Meissner fraction increases from a few percent to 20% and then starts to decrease. In the X-ray powder diffraction pattern for the sample with the maximum Meissner fraction, it is obvious that the infinite-layer structure has been decomposed and a new structure becomes the major phase. It appears that the new structure is the 0223 structure which consists of rock-salt and the infinite-layer type blocks. This material is likely to be a new superconducting cuprate.