Prediction of bubble concentration profiles in vertical turbulent two-phase flow

In vertical bubbly flow, the bubbles are not distributed evenly across the flow section. Several investigators have observed a wall-skewed bubble concentration profile in a vertical upward flow. This paper presents an analysis that predicts this type of bubble distribution by incorporating into the equation of motion a lateral force due to the relative velocity of the two phases and the eddy diffusivity of the liquid. Comparison of analysis and experiment shows good agreement.     

The 1H NMR spectra of some norbornene derivatives,a LIS study

The ¹H NMR spectra of 2-exo-hydroxymethyl-3-endo-methylnorbornene and the corresponding 2-endo-3-exo isomer have been completely assigned with the aid of lanthanide reagents. This enabled a full analysis of the unusual spectrum of 2-exo-hydroxy-methyl-3-endo-methylnorbornene to be undertaken, confirming the proposed structure. The ΔEu values for 2-exo-hydroxymethyl-3-endo-methylnorbornene and the 2-endo-3-exo-isomer have been used to test the effect of rotational averaging on the calculated pseudo contact shifts. Good agreement is obtained for a dynamic model in which the Eu atom exchanges between two sites on the oxygen atom of the OH bond, and in which the rotational equilibrium about the CH? CH₂OH bond is explicitly considered.     

Multi-axial low-cycle-fatigue test rig

A multi-axial rig for testing aircraft gasturbine compressor and turbine disks is described. The rig is based on the closed-loop electro-servo hydraulic control principle. This principle combines the use of hydraulic and electronic components not only to control the loads but to hold the true disk position. Nonrotating disks can be loaded to produce stresses which closely simulate loading experimenced by disks in service. Disks with up to 100 loading points and with diameters between 2.5 in. and 18 in. are acceptable within this framework, with loads up to 25,000 lb per loading point, at frequencies up to 7 Hz, and at temperatures in excess of 1500°F. The rig has demonstrated its effectiveness as a useful laboratory tool for compressor and turbine-disk low-cycle fatigue and cyclic stress-rupture life evaluation.     

Tachyons without paradoxes

Tachyon paradoxes, including causality paradoxes, have persisted within tachyon theories and left little hope for the existence of observable tachyons. This paper presents a way to solve the causality paradoxes, along with two other paradoxes, by the introduction of an absolute frame of reference in which a tachyon effect may never precede its cause. Relativity for ordinary matter is unaffected by this, even if the tachyons couple to ordinary particles. Violations of the principle of relativity due to the absolute frame would appear only in the case of free tachyons.     

Furans in synthesis 4. Silyl furans as butenolide equivalents

The preparation and utilization of butenolide anion equivalents 5 and 6 in alkylation sequences is described. Treatment with CH₃CO₃H unmasks a latent butenolide moiety providing a general route to 3- and 4-alkyl 2(5H)-furanones.     

Preparation and reactions of 2-benzenesulphonyltetrahydropyran

The anion derived from 2-benzenesulphonyltetrahydropyran (1) reacts with various electrophiles to give alkylated or acylated products some of which are useful precursors for spiroketal synthesis.     

A. translation of J. X. Lu's “an existence theory for resolvable balanced incomplete block designs”

In 1984, J. X. Lu proved the following statement. Given any k and λ, there exists a constant c(k, λ) such that an RB[v,k,λ] exists for all v > c(k,λ) satisfying the usual necessary conditions. Lu's paper was written in Chinese and, unfortunately, its accessibility is limited. We have translated Lu's paper into English and have also given a new interpretation of his constructions for resolvable block designs. © 1995 John Wiley & Sons, Inc.     

The relevance of ester exchange in oxalacetic esters to the decarbonmonoxylation reaction

Oxalacetic esters undergo ester exchange at 120°C, at which temperature loss of CO does not occur. A new mechanism is proposed for the decarbonmonoxylation reaction.