Core Cylinder Research Articles

Mechanical Considerations in CW Linacs

An 80-MHz radio-frequency quadrupole (RFQ) linac has been designed, fabricated and operated at 100% duty factor (cw) for the Fusion Materials Irradiation Test (FMIT) project at Los Alamos.1 This paper describes the design features, fabrication techniques, and operational problems of the device. The RFQ is an assembly of heavy steel, copper-plated weldments. It measures about 15 ft (4.5 m) long by 5 ft (1.5 m) in diameter and weighs over 12 t. Major components are two pair of diametrically orthogonal vanes mounted in a core cylinder. The core is assembled into a manifold cylinder that couples rf power into the vane quadrants. The design features discussed include assembly of hollow wall, flood-cooled components; highconductivity rf seals; removable and adjustable vanes; and tuning devices. Fabrication challenges such as close-tolerance weldments, vane-tip-contour machining and large-component plating requirements are covered.

FIELD TECHNIQUES USING THE ACETYLENE BLOCKAGE OF NITROUS OXIDE REDUCTION TO MEASURE DENITRIFICATION

Four techniques for the measurement of denitrification rates in the field were compared. All involved the use of acetylene (C2H2) to block nitrous oxide (N2O reduction and subsequent measurement of accumulated N2O. Two extracted core techniques were compared with two in situ cylinder techniques. The single-wall cylinder technique involved partial insertion of a PVC tube into the soil, sealing the head-space, injection of C2H2 into the headspace and, after suitable time periods, assaying N2O concentration in the headspace. A double-wall cylinder technique was devised to allow more rapid C2H2 introduction into the soil core from an interwall space in situ. A comparison of the four techniques on a 1-m2 area in the field showed large spatial variability. Estimates of denitrification rates decreased in the order double-wall cylinder, single-wall cylinder, extracted encased core and extracted loose core. Variation among replicates varied between sampling occasions but, on aveage, decreased in the order single-wall cylinder, extracted encased core, extracted loose core and double-wall cylinder. Key words: Denitrification, field measurement techniques, acetylene blockage, spatial variability

Free convection of gases in a horizontal cylinder with differentially heated end walls

The free convective flow of gases in a horizontal cylinder (radius to length, r 0/ L = 0.1) with different end temperatures and a linear temperature gradient at the wall was characterized by laser Doppler anemometry. Experiments were conducted over a wide range of Rayleigh numbers (74 < Ra < 1.3 × 10 6, with Ra ∝ r 0 3), which were varied via gas species and gas pressure. In the vertical mid-plane the velocity profiles in the cylinder core region at low Ra and in the end regions at high Ra were as expected from 2-D models. For the end regions, however, pronounced 3-D flow behavior was observed. It was found that only part of the fluid flows along the cold (hot) thermode into the lower (upper) half of the cylinder. The remaining part changes the flow direction by dropping (rising) at the side wall over a considerable distance from the respective thermode.

The core cylinder in the junctional SR of single intact skeletal muscle fibers of the frog after quick-freezing: Its topography

The "core cylinder" (CC) represents confluent electron lucencies seen in the junctional SR (JSR) when skeletal muscle is fixed in the presence of cations such as ruthenium red. CCs are a consistent feature in quick-frozen muscle fibers (Fig.l), both in the resting state and after various intervals between stimulation and freezing, incl. tetanus (5 sec, 50Hz). The CCs are excentrically located inside the JSR and are separated from the junctional membrane toward the transverse tubule by the coextensive line(CL) and from the rest of the membranous envelope of the JSR by granular material (junctional granules, JG). JGs are also found elsewhere in the free SR. Whereas the JGs fill the JSR completely in many cases, often they are separated from the JSR envelope by a peripheral clear halo except in the region of the CL; in favourable sections they form regular rosettes about the CC (Fig.3). Very frequently, the CC loose their more circular configuration (in one dimension)(Fig.4), with flares connecting the CCs with the peripheral halo at either end of the CL (Fig.3). The junction between the electron-lucent flares and the ends of the CL subtends, approximately, the location of the staggered rows of pits on the E face of the freeze-fractured JSR(Fig.2).

Sound wave propagation in composite slow waveguides.

The composite slow waveguide is an underwater acoustic slow waveguide and has a double-layered structure consisting of an inner core cylinder and a surrounding outer annular cylinder. This slow waveguide works as an end-fire radiator when operated with a point source attached on its end. In this paper, a theoretical study on propagation of sound waves along the composite slow waveguide is performed. The phase velocity, cutoff wave number, sound pressure distribution and acoustic power are obtained in dependence on parameters pertaining to the composite system. A new propagation phenomenon which is not obtainable in usual single-structured slow waveguides is described. The limiting case of the composite slow waveguide-a thin-layered composite slow waveguide-is also discussed.

Portable Hand‐Operated Soil Core Sampler

AbstractA simple sampling apparatus was developed to take soil cores for characterizing soil‐water relations. A portable steel frame, which is anchored to the soil surface by the operator's weight and by stakes driven into the soil, provides support for a hand‐operated 2‐ton hydraulic jack which pushes the core cylinder into the soil without impact or vibration. The method is labor‐intensive but provides highquality soil cores.

1. Manometric Studies for Evaluation of Ano-Rectal Activity

Quantitative anorectal manometry by open tipped method modified cylinder core was examined on 70 normal subjects ranging birth to adult for the evaluation of physiological anorectal function and also discussed the methodology of pressure studies.At the neonatal period, especially during first week of life, anorectal pressure is very low, as well as recto-sphincteric reflex shows inactive. However, greatest rate of growth takes place unti 2 months after birth. The length of anal canal develops markedly in the second decade. From the physiological point of view, we divided functional anal canal into 3 parts, ie, puborectalis zone, internal sphincter zone, external sphincter zone. With introduction of increasing volume of air into the rectal balloon, the internal sphincter zone showed gradual decrease of basal tone and the puborectalis zone a similar reduction of tonic activity.For the assesment of anorectal defecative motility, we advocate to measure the REFLEX ANORECTAL PRESSURE PROFILE which composed of projecting the pressure fall on the resting anorectal pressure profile. It demonstrates that the anorectum reduces its tone from upper part to downward with proportional to the increase of rectal pressure.

Numerical Solutions of Flow between Rotating Cylinders

The paper presents solutions of the laminar flow of a Newtonian fluid between cylinders with non-coincident axes, where the core cylinder rotates about its axis. The solutions have been obtained by means of an adapted version of the finite-difference procedure of Gosman et al. (1). The results show that the inclusion of convective transport terms (which in previous analyses have been neglected or included only approximately) may have an appreciable effect upon the flow field and, in particular, upon the pressure field around cylinders.

Should standard cube test specimens be replaced by test specimens taken from structures?

Presents results obtained from investigations in which the concrete strength has been determined at the same time on standard test specimens, job-stored test specimens, and core cylinder specimens drilled from structures.