Internal Sleeve Research Articles

Tests to Examine Plastic Behavior of Knee Joints in Cold-Formed RHS

This paper describes tests on various types of knee joints for steel portal frames constructed from cold-formed rectangular hollow sections (RHS) to examine the ability of the connections to form plastic hinges. Welded stiffened and unstiffened knee joints, bolted knee joints with end plates, and connections with a fabricated internal sleeve were included in the experimental investigation. Most connections tested under opening moment failed by fracture in the heat-affected zone of the RHS near the weld. The connections tested under closing moment failed by web local buckling, which occurred near the connection. While the stiffened and unstiffened welded connections satisfied the strength interaction requirements in the available design guides, the connections did not maintain the plastic moment for sufficiently large rotation to be considered suitable for a plastic hinge location. The unstiffened welded joints were not able to reach the plastic moment. The use of an internal sleeve moved the plastic hinge in the connection away from the connection center-line and reduced the stress on the weld between the legs of the connection. It was found that sleeve connections were capable of sustaining the plastic moment for large rotations considered suitable for plastic design.

Modulation and Manipulation of Gas Chromatographic Bands by Using Novel Thermal Means

The maturity of the gas chromatography technique belies the continuing search for improved operating methods. Cryogenic methods, applied in many forms, have been used for many years to trap volatile compounds in chromatography. Recent work has demonstrated an alternative approach to band accumulation. A small tube incorporating an inter-nal sleeve cooled cryogenically, placed over a gas chromatography capillary column, can be moved back-and-forward over the column to permit collection and remobilization of focused bands. The movement frequency or timing can be altered to give different operational modes and outcomes. Results demonstrate that peaks can be fully accumulated just prior to a detector then rapidly flushed into the detector, allowing considerable increase in peak height as the peak width diminishes. Applications illustrate that all or selected peaks in a chromatogram can be thus modified by the trap. Column bleed can likewise be collected and then re-eluted, leading to a novel presentation of the molecular constituents of the bleed. With multidimensional gas chromatography, heart-cuts from the first column can be trapped and focused at the head of the second column, then rapidly re-injected into the second column leading to certain advantages. Furthermore, by rapid modulation of the cold trap, a single peak can be cut into a series of separate pulses, either into a detector or into a second column. This allows unusual expression of a chromatographic peak profile, and can be incorpo-rated into a comprehensive GC experiment.

A modified centrifuge apparatus for extracting soil solution

Abstract A modified centrifuge apparatus for extracting soil solution is described. The device, constructed of polypropylene, has the advantages of simple assembly, ease of cleaning and reduced contamination. An internal sleeve permits quick and easy interchange of soil samples between centrifugations. Soil contained in the sleeve can be used for short term plant growth studies allowing solution, from the entire undisturbed soil volume, to be collected for analysis immediately after plant tops are harvested.

Calculation of Acoustical Resonances in Irregular Cavities With Application to Noise-Induced Stress in Expansion Joints

An analytical and experimental study of the acoustic behavior of seven and nine corrugation expansion joints (bellows) used in a nuclear reactor is presented. Resonant frequencies obtained from a computer program using a matrix method are given. Experimental test results on seven corrugation expansion joints are in good agreement with the computations. It is concluded that the calculation of acoustic frequencies of expansion joints with internal sleeves can be utilized to avoid the coincidence of these frequencies with those of a mechanical or flow-induced noise nature and thus reduce the loads on expansion joint corrugations.

Perforated-Pipe Water Intake for Fish Protection

Since a major concern in the design of pumping station water intakes is the possibility of damage by fish drawn into the facility, some kind of screening system must be installed to minimize or eliminate this possibility. The potentially adverse impact of water intakes is resolved by the implementation of physical screens, which exclude all debris, including fish. The germane difficulties of screens, i.e., the necessity of lowering the approach velocity, poor velocity distribution across the screen, and danger to fish are overcome by the installation of a perforated-pipe inlet with an added internal perforated sleeve. The benefits of such a device, i.e., relative ease of maintenance, uniform approach velocity, uniform inflow, and protection for fish, cannot be equalled by ordinary means of physical screening. For water intakes up to 100,000 gal/min, the inner sleeve type of perforated-pipe intake provides a viable solution to the problem of screening.

Paper 8: Boiler Circulating Canned Motor Pumps

This paper presents all the technical aspects of the pump constructed by Société Rateau for the first French 600-MW controlled circulation boiler. First, the general organization of the pump with an underslung motor will be presented, then each of the most important sub-sections of the machine will be described: the two-discharge branch volute, the thermal barrier, the fixing system of the inductor internal sleeve, the multi-pad hydrodynamic bearings and thrust, the tight terminals, etc. For each of these parts the authors will give the reasons that led to their selection and will present alternative solutions used on other machines. The paper will also describe the pump isolating elements such as valve and double wedge gates. Finally, the test loop on which the prototype pump has been tested at full power and temperature will be discussed, and the main results will be presented.

Pin retention for extensive posterior gold onlays

The restoration of the coronal portion of a posterior tooth which has undergone extreme destruction can be accomplished by the construction of a cast gold onlay which derives its retention from pins or dowels. The retentive pins engage the sound dentin remaining in the tooth, and they can act in conjunction with either limited internal wall retention or external sleeve retention.