Pair Of Rods Research Articles

The Fort St. Vrain high temperature gas-cooled reactor: I. Low power physics tests

The core was loaded with fuel and reflector elements with subcriticality ensured by temporary neutron absorbers. Pulsed-neutron measurements initially showed the core to be more subcritical than calculated. Adjustment of the calculational model by including the correct reflector impurities led to good agreement between calculated and measured values of the multiplication constant and prompt neutron generation time. Axial fluxes showed consistent good agreement between calculated and measured values for a variety of configurations, but the ratios of average regional fluxes in the top half of the core to their respective regional averages in the bottom half differed from the calculated ratios by as much as 10%. The helium pressure coefficient was essentially zero. The calculated and measured isothermal temperature coefficients up to 300°F agreed within 3%. Control rod calibrations using the reactivity computer were satisfactory only for the central rod pair. Peripheral rod pairs were calibrated by comparison to the central rod pair.

Natural frequencies of two cantilevers joined by a rigid connector at their free ends

The derivation of the equations of motion is given for a system consisting of two identical parallel cantilevers joined by a rigid connector at their free ends. Elementary beam theory is employed, and it is observed that the longitudinal and flexural deformations of the system are coupled through the boundary conditions but not through the differential equations. The associated free vibration problem is solved, and it is shown that the frequency determinant can be factored, yielding two independent frequency equations. One of these corresponds to the pure, free longitudinal motion of a pair of rods connected by a rigid body at their tips (both rods being equally stretched or compressed simultaneously), whereas the second and more complicated frequency equation is pertinent for the system undergoing flexural deformations in both rods, stretching in one rod, and compression in the other. This latter frequency equation is solved numerically, and the variations of the first six natural frequencies with connector thickness and length parameters are displayed graphically. Two orthogonality conditions for the eigenfunctions are derived, and a relatively simple form for the normalizing factor is presented.

A Physical Method for Deriving the Electrostatic Interaction between Rod-Like Polyions at All Mutual Angles

The screened Coulomb interaction between polyelectrolyte cylinders immersed in an ionic bath is examined. The electrostatic force and torque acting between a pair of unlike rods is formulated for all separations in which the electrostatic potential on some dividing surface between rods can be written as a linear superposition of isolated cylinder potentials. (The surface potential on the rods themselves may be much higher than that permitted by a superposition approximation.) The mutual energy in the case of skewed rods is found to be exponential in separation and proportional to 1/sin theta where theta is the twist angle of one rod relative to the other. Rods with similar charge repel each other with a torque acting to make the rods perpendicular while rods of opposite charge attract with the parallel arrangement preferred.

An Application of Harrington Instrumentation for the Cases With Spinal Deformity and Spine Injury

Based on the clinical experience by Harrington Instrumentation techuique on twenty one cases with scoliosis deformites, a reconstructive surgery using Harrington Instrumentation was performed succesfully for three cases with spinal deformities due to spine and spinal cord injury, having secure reduction and immediate fixation.Case 1: 14 years old boy. Lumbosacral spondylolisthesis was reduced by two distraction rods and fused posteriorly.Case 2: 7 years old boy. Kyphotic collaps spine due to thoracic spinal cord injury was corrected by a pair of compression rods with posterior short fusion.Case 3: 32 years old woman. Dislocation of lumbar spine was reduced by using a distraction rod and sacral bar and fused posteriorly.

On the stability of certain motions of a rigid body with elastic rods and liquid: PMM vol. 36, n≗ 1, 1972, pp. 43–59

We consider the motion of a free rigid body with three pairs of elastic rods and with a cavity containing a liquid, in two cases: in a central Newtonian force field and in the absence of external forces. By an application of Rumiantsev's theorem [1] we obtain sufficient stability conditions for relative equilibrium in a circular orbit and to uniform rotations of this system. We show that the presence of a liquid with a free surface in the cavity and the connection of elastic rods to the body have a destabilizing effect on the stability of the corresponding unperturbed motions of the unaltered system. We also point out sufficient stability conditions in the case when less than three pairs of rods are attached to the body. For a large Young's modulus the stability conditions obtained lead (in the absence of the liquid) to the well-known sufficient conditions for the stability of a rigid body. Stability conditions for the case when one pair of rods is attached to the body and when there is no liquid are compared with the stability conditions obtained in [2, 3]. In connection with the assertion made in [2, 3] regarding the novelty of the method used, we remark that this method was previously developed by Rumiantsev and was applied to the solution of a number of problems on the stability of the steady-state motions of a rigid body with a liquid filling [4].

A Karyotype Study ofVaranus MonitorLinn

SUMMARY1. Karyotype in Varanus comprises of 40 chromosomes; 8 Vs, 8 rods and 24 dots. The fundamental number of arms according to present investigations is 48.2. One pair of rods, in the late mitotic prophase and at metaphase II has a knob like structure at one of the ends. Second pair of V in order of size has a constriction and appears to be nucleolar chromosome.3. Mean chiasma frequencies, cell variance and bivalent variance for the macrochromosomes have been calculated.4. One pair of microchromosomes is very small and is hardly visible under the oil immersion. This pair stains poorly even at metaphase I and is labelled as « m » chromosome.5. Bone marrow and the spleen of the female show variation in chromosome number ranging from 32 to 40, but most of the plates have the number as 32±1,35±1,38±1 and 40 ±1.6. Morphologically differentiated sex pair seems to be lacking.

The film tensiometer

The Film Tensiometer is described. It is an instrument capable of continuous measurement of the surface tension of a solution undergoing constant changes of its surface properties. The instrument uses continuous sampling of the test solution and measures the surface tension as a function of the pull exerted on a pair of vertical rods by a thin moving liquid film supported by these rods. A variation of surface tension causes a change of the force applied to the rods, resulting in movement of one of the rods which is spring loaded. This movement is converted by a transducer to a continuously recorded electrical signal. The force produced by the film on the rods is directly proportional to the product of the surface tension times twice the film length and is nearly, independent of film width and thickness. The instrument can be calibrated to an accuracy of ± 0.5 dynes/centimeter and will detect a change of surface tension less than 0.3 dynes/centimeter. Instrument contamination has not proven to be a problem. The instrument can be easily applied to direct measurement and process control.

Finite Solid Acoustic Filters

Most of the previous theoretical work on acoustic filtration has dealt with idealized infinite structures. The present paper is a theoretical study of finite solid filters together with an experimental check of the results obtained from the theoretical discussion. Two types of filters are considered. The first consists of a solid rod loaded at equal intervals with heavy masses; the second consists of a structure in which rods of one material are alternated with rods of a second material, each pair of rods being similar to the next pair. Expressions are derived for the power transmission ratios and for the phase changes which occur between successive sections of the filters. Experimental filters, which were designed to approximate the theoretical considerations, are tested for their transmission characteristics. The acoustical system is set into vibration by a modified dynamic speaker unit. The vibrations in the system are detected by phonograph pickups. Satisfactory agreement of theory and experiment is obtained.