Almost-periodic dissipative actions of semigroups

Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 40, No. 1, pp. 110–113, January–February, 1988.     

Evaluating Re-order Levels and Probabilities of Stockout during a Lead Time for Some Stock-Control Models

When several suppliers are concurrently used to replenish one stock item, it is often of interest to compute the mean and the variance of the effective lead time, i.e., the minimum of all lead times. However, in many cases, especially with non-identical lead time distributions, these quantities do not have closed form expressions and their calculation can be complicated. Difficulty in computation also arises in evaluating demand during lead time, even if there is only one supplier. This paper presents a numerical integration method using Gaussian quadrature to evaluate the effective lead time mean and variance, re-order level and the probability of stockout during the effective lead time. The Gaussian quadrature rules are easy to implement and several data sets are used in the paper to demonstrate the method.     

Bifunctional chiral synthons via biochemical methods. : VI. C5 isoprenoid units.

Two methods for the preparation of the isoprenoid chiron $\text{4}$ have been developed using a microbial kinetic resolution of $\text{5}$ and an enantiotopically selective hydrolysis of $\text{7}$ catalyzed by PLE.     

The microwave spectrum and structure of trimethylamine-monofluoroborane

The microwave spectra of the ¹¹B¹⁴N, ¹¹B¹⁵N, ¹⁰B¹⁴N and ¹⁰B¹⁵N species of trimethyl-amine-monofluoroborane have been assigned in order to evaluate the B—N distance. Analysis of the rotational constants using either the single or double substitution methods did not give highly precise results. However, by assuming parameters for the amine moiety found in other complexes and fitting the moments of inertia a value of 1.63 ± 0.01 Å was estimated. The method of predicate observables, an alternative fitting process, resulted in d(BN) = 1.633 ± 0.006 Å along with estimates for the other structural parameters.     

The microwave spectrum,structure and nuclear quadrupole coupling constants for stibabenzene

The microwave spectrum of 121-SbC₅H₅, 123-SbC₅H₅, β-dideutero 121-SbC₅H₃D₂ and 123-SbC₅H₃D₂ has been assigned in the region 26.5–40.0 GHz. The respective rotational constants and uncertainties are: A = 4512.69 ± 0.42, B = 1738.00 ± 0.01, C = 1254.51 ± 0.01; A = 4512.84 ± 0.30, B = 1729.80 ± 0.01, C = 1250.22 ± 0.01; A = 4176.18 ± 0.33, B = 1660.94 ± 0.01, C = 1188.15 ± 0.01; A = 4176.60 ± 0.61, B = 1652.94 ± 0.03, C = 1184.03 ± 0.03 (in MHz units). The structure is found to be planar, C_2v in symmetry. The $\text{d(}\text{Sb-C}\text{) = 2.050 ± 0.005}\text{A}\text{?}$ and ∠CSbC = 92.9° ± 1.0°. The nuclear quadrupole coupling constants for the 121 and 123 antimony isotopes are χ_aa = 456.4 ± 4.1 MHz, η = 0.396 ± 0.008, and χ_aa = 583.00 ± 5.3 MHz, η = 0.399 ± 0.008, respectively. Several alternate techniques using the coupling constants as data support a σ-donating property for antimony.     

On the stability of elastico-viscous flow between roating cylinders

Summary Thomas andWalters (9, 2, 3) have recently shown that for a certain elastico-viscous liquid, the presence of elasticity has a destabilizing effect on the flow. The problem is reconsidered in the present paper for another idealized elastico-viscous liquid which is as simple as that considered byThomas andWalters. It is shown that in this case, the presence of elasticity has a stabilizing influence. It is concluded that a stability experiment would be a useful addition to the experiments usually set up to characterise elastico-viscous liquids.     

Tests of quantum chromodynamics and a direct measurement of the strong coupling constant αs at √s=30 GeV

We report the measurement of the reaction e⁺ + e^? → hadronic jets at a center-of-mass energy √s=30 GeV using the MARK-J detector at PETRA. By measuring the energy and angular distribution of both neutrals and charged particles we were able to isolate unambiguously the three-jet events in a kinematic region where the backgrounds from q$\text{q}$ and phase space contributions and other processes are small. Various comparisons of the data with quantum chromodynamics were made. The relative yield of three-jet events and the shape distribution of the events enable us to determine α_s = 0.23 ± 0.02 (statistical error) with a systematic error of ± 0.04.     

Condition under which stress matrix is diagonal

Summary The conditions under which the stress matrix of the flow of a viscoelastic material may be diagonal are examined.

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Zusammenfassung Es werden die Bedingungen untersucht, unter denen die Spannungsmatrix des Fließens eines viskoelastischen Materials diagonal sein kann.

     

The Effect of Temperature,Agitation and Content of Gold on the Thickness of Electroplated Gold at Various Current Densities

The effect of temperature, agitation, and content of gold in the solution on the thickness of electroplated gold at various current densities can be easily explained by their effect on the limiting current. Diffusion coefficient of aurocyanide ion, thickness of diffusion layer, and the activity of aurocyanide ion in the bulk solution are the three major factors to affect the limiting current. It was found that the change of temperature will affect both diffusion coefficient and thickness of diffusion layer. However, the thickness of diffusion layer is mainly determined by the means of agitation.     

Instability of Electromagnetic Ion Cyclotron Harmonic Waves in Plasmas

The stability of electromagnetic ion cyclotron harmonic waves propagating normal to an external magnetic field is studied for plasmas whose ions possess loss cone type velocity distributions. It is found that, if the ions are stationary, no instability develops except in the extreme case when the ratio of parallel to perpendicular "temperatures" of the ions is of the order mi/me, where mi and me are the ion and electron masses respectively. However, for the case of two counterstreaming ion beams in a neutralizing background of electrons, instability at zero frequency and near the first several ion cyclotron harmonics can occur if the streaming velocity is of the order of the electron thermal speed.