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761.
762.
Consider an edge-weighted graphG = (V, L), and define ak-cover C as a subset of the edgesL such that each vertex inV is incident to at least one edge ofC, and|C| = k. GivenG andk, the problem is to find ak-cover of minimum weight sum. This paper presents characterizations of minimumk-covers, and shows their weight to be convex with the parameterk. An efficient algorithm is presented which generates minimumk-covers continuously as the parameterk ranges over all feasible values, together with a proof of optimality. The computational order of this algorithm is found to be|V| ? |L| 2. 相似文献
763.
764.
R.W. Wodrich E.G. Auld J.M. Bailey G.A. Beer B. Dreher U. Gastaldi H. Kalinowsky E. Klempt R. Landua K. Merle K. Neubeckef Chr. Sabev R.D. Wendling B.L. White 《Nuclear Physics A》1982,384(3):386-400
X-ray transitions to the 4F, 3D, and 2P atomic levels of p?He have been observed with antiprotons stopped in He gas at 4 and 1.1 atm NT. The population by radiative transitions of the 3D level in gas YM(4atm) = (28±14)% and YM(1.1 atm) = (43±22)% exceeds by more than one order of magnitude that measured in liquid He. The annihilation width of the 3D level Γa3D = 2.8±1.0 × 10?3eV is determined from the ratio between the numbers of X-rays feeding and depopulating the 3D level. The strong-interaction shift of the 2P level ε(2P) = ?14±6 eV is obtained by inputting the experimental X-ray yields into a cascade calculation, the results of which are in good agreement with well-established data from muonic, pionic, and kaonic helium. 相似文献
765.
The parameters controlling power transmission from a vibrating machine to the seating structure, via spring-like vibration isolators, are investigated. The low frequency range is considered where the machine moves as a rigid body. It is shown that the finite seating structure can be modelled by an equivalent structure of infinite extent for frequency averaged power transmission calculations. Power transmission to a finite and an infinite beam via a mass and spring in series is measured experimentally and compared with theoretical predictions. The power transmission is measured by two proposed methods; the first involves the real component of the seating impedance, and the second the transfer impedance of the isolator. 相似文献
766.
M.G. White R.A. Rosenberg S.-T. Lee D.A. Shirley 《Journal of Electron Spectroscopy and Related Phenomena》1979,17(5):323-344
The He(I) photoelectron spectra of the Group IV—VI diatomics GeO, GeS, GeSe, GeTe, SnS, SnSe, and SnTe are presented. The outermost valence structure of these molecules is similar to that observed in the lighter series CO, CS, etc. of this valence isoelectronic group; in each case a relatively sharp peak is assigned to ionization from the nominally non-bonding 3σ orbital and a broader band to ionization from the bonding 1π orbital. At higher binding energies the spectra exhibit several peaks where only a single peak is expected, from the (2σ)?1 hole state. This structure is assigned to correlation peaks resulting from configuration interaction among hole states of 2Σ+ (Ω = ) symmetry. Semi-empirical CNDO—MO calculations have been performed for these molecules, and the results are used to interpret the observed trends. In addition, a simple molecular orbital model is employed to estimate the importance of spin—orbit coupling in the valence electronic structure of the heavy IV—VI ions. 相似文献
767.
The rate constant for the combination of 2,2-dichloro-1,1,1-trifluoroethyl radicals has been measured by applying the rotating sector technique to the gas phase photochlorination of 2,2-dichloro-1,1,1-trifluoroethane at 315°K. The observed value is 6.89 × 1012 cc/mole.sec. This value is in excellent agreement with measurements by Wampler and Kuntz which yielded a temperature-independent value of 6.6 × 1012 cc/mole.sec. The measurement by Wampler and Kuntz was determined from the photochemical system (CF3CCl3 + C-C6H12 + hν). The Arrhenius parameters for the reaction CF3CCl2· + Cl2 → CF3CCl3 + Cl were found to be given by the expression log k3 = 12.10 ? 5830/2.3RT (units in mole, cc, and sec). This is a relatively high activation energy for a chlorination reaction and makes the reaction ever slower than the chlorination of chloroform. 相似文献
768.
To determine the void fraction in a tube of a rotating heat exchanger, an analytical investigation was undertaken to model frictionless two-phase flow boiling. Steady, one-dimensional separated two-phase conservation equations in differential form, were first applied to a stationary system. The equations were integrated between the inlet and exit of the flow channel to yield three coupled algebraic equations. The algebraic equations were then modified to represent rotating systems. To obtain closure, the velocity ratio, mass quality and void fraction are defined as a function of pressure.
A numerical technique was used to solve the equations. Sample results are presented in a graph of mass quality versus void fraction. The graph demonstrates that a minimum heat input must be exceeded to change from a single-phase flow to saturated two-phase flow boiling. Also, the void fraction was found to increase for increasing heat input, decreasing mass flow rate, increasing inlet mass quality and decreasing pressure difference between the inlet and exit. 相似文献
769.
Acta physica Academiae Scientiarum Hungaricae - Thirty years ago American and Hungarian groups of researchers announced the detection of radar echoes from the moon. The experiments were performed... 相似文献
770.
M. H. Reeve M. C. Brierley J. E. Midwinter K. I. White 《Optical and Quantum Electronics》1976,8(1):39-42
We describe measurements in which the radiative losses from a multimode fibre have been resolved into three components. These are the Rayleigh Scatter component from the material, the loss by tunnelling from the modes closest to cut-off into the surrounding material, and the forward scatter loss caused by imperfections in the fibre that are large compared to a wavelength. 相似文献