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Sharp thin cutting edge is held in head of milling machine designed for metal working. Controls of machine are used to position cutting edge in same plane as vibrating specimen. Controls then are operated, making blade come into contact with specimen, to cut it into shapes and sizes desired. Cut surfaces appear mirror-smooth; vibrating mechanism causes no visible striations.
The theoretical optimum acoustic impedance for higher order spinning modes was studied in cylindrical ducts with a boundary layer at the outer edge of a uniform flow. All of the propagating modes were considered from highly propagating to nearly cut-off. It was observed that the mode cut-off ratio uniquely determined the optimum wall impedance and maximum possible attenuation for a given boundary layer thickness, Mach number and frequency. The implications of this phenomenon are quite important in noise suppressor design. Instead of the acoustic power distribution among all of the propagating modes, only the power distribution as a function of cut-off ratio needs to be known. Also, the far field radiation pattern is a function of modal cut-off ratio, and much needed information for liner design can be obtained from these more easily obtained data.
During automatic horizontal path captures, the (Terminal Configured Vehicle) B-737 airplane maintained smaller than designed path intercept angles and experienced a sawtooth bank angle oscillation during its turn towards the path. From flight data, it was determined that these anomalies were caused by the improper output of the course cut limiter in the horizontal path control law. The output from the course cut limiter did not obtain its full value and it was calculated stepwise discontinuously. The automatic horizontal path captures were then conducted on the TCV B-737 airplane real-time simulation. The path intercept angles were maintained properly and no bank angle oscillation was encountered. Data showed that the course cut limiter was calculated at its full value in a continuous manner. The intermediate calculations of the course cut limiter in the airplane's navigation computer were rewritten and rescaled in such a manner that truncation errors could be minimized. The horizontal path capture tests were then reflown. The airplane maintained the proper path intercept angle and no bank angle oscillations occurred on any of the tests.
Chevron cutting is shown to occur in different forms depending on the type of tire and the rubber on the running surface. Hardest wear is shown by the main tires of the B-747. Four defects occurred, in the form of two rip separation and two breakouts of the running surface. Tires capped by Thompson are more affected than any of the other rubber-capping fabrics. For Thompson tires, Chevron Cutting is greatly reduced with a fiberglass-rubber mixture. For Goodyear tires, it is eliminated with spiral wrap rubbercapping; resistance to damages through cuts seems to be more positive for Goodyear tires. For Mader tires, the extent of Chevron Cutting is generally smaller than for Thompson cappings.
Tool facilitates repetitive cutting of fibrous sheets. Flexible aluminum tape allows metal strips folded back on themselves, exposing fresh material for cutting. More than one strip folded back, and cutting width therefore increased in multiples of strip width. Developed for cutting strips of alumina-fiber matting, tool also used on such materials as felts, textiles, and sheet metals.
Fixture for power saw saves time, eliminates waste, and ensures precision. Positions tube for 45 degrees end cut, then repositions for cut at 90 degrees to first cut. Roller chain holds tube in place for both cuts.
The rudder effect of a sport airplane at high angles of attack was to be improved. This made it necessary to make a cut-out in the center of the continuous elevator so as to enlarge the rudder downward. This cut-out which reduced the rudder area by 12.5 percent changed the static stability of the airplane as well as the elevator effect. Flight measurements showed the stability zone with locked elevator to be 1.8 percent less at full throttle and at idling to be 1.3 percent less than the mean wing chord. The effect of the cut-out on the control forces could not be determined owing to insufficient instrumental accuracy at the extremely low existing forces. The measurement of the static controllability resulting from the cut-out manifested an 18 percent drop in elevator effect at full throttle and a 10 to 20 percent drop at idling, depending on lift.
CUTSETS computer program identifies all minimal cut sets for given node. Software package contains subprograms that solve for minimal cut sets of fault trees and digraphs by use of object-oriented programming techniques. Cut-set codes used to solve graph models for reliability analysis and identify potential single-point failures in modeled system. Includes utility subprogram that converts popular COD-format diagraph-model-description files into text input files suitable for use with other CUT-SETS subprograms. FEAT (MSC-21873) and FIRM (MSC-21860). Written in C language.
The cut-off is a unique feature associated with duct acoustics due to the presence of duct walls. A study of this cut-off effect on the computations of duct acoustics is performed in the present work. The results show that the computation of duct acoustic modes near cut-off requires higher numerical resolutions than others to avoid being numerically cut off. Duct acoustic problems in Category 2 are solved by the DRP finite difference scheme with the selective artificial damping method and results are presented and compared to reference solutions.
The challenge of our new National Space Policy and NASA's Vision for Space Exploration (VSE) is keyed to the development of more effective space access and transportation systems. Optimizing in-space systems through innovative cross cutting structural designs that reduce mass, combine functional requirements and improve performance can significantly advance spacecraft designs to meet the ever growing demands of our new National Space Policy. Dependence on limited structural designs is no longer an option. We must create robust materials, forms, function and evolvable systems. We must advance national policy objectives in the design, development, test and operation of multi-billion dollar new generation crew capsules by enabling them to evolve in meeting the requirements of long duration missions to the moon and mars. This paper discusses several current issues and major design drivers for consideration in structural design of advanced spacecraft systems. Approaches to addressing these multifunctional requirements is presented as well as a discussion on utilizing Functional Analysis System Technique (FAST) in developing cross cutting structural designs for future spacecraft. It will be shown how easy it is to deploy such techniques in any conceptual architecture definition or ongoing preliminary design. As experts in merging mission, safety and life support requirements of the frail human existence into robust vehicle and habitat design, we will conquer the final frontier, harness new resources and develop life giving technologies for mankind through more innovative designs. The rocket equation tells us that a reduction in mass optimizes our propulsive results. Primary and secondary structural elements provide for the containment of gases, fluids and solids; translate and sustain loads/impacts; conduct/radiate thermal energy; shield from the harmful effects of radiation; provide for grounding/bonding of electrical power systems; compartmentalize operational functions; and provide physical interface with multiple systems. How can we redefine, combine, substitute, rearrange and otherwise modify our structural systems to reduce mass? New technologies will be needed to fill knowledge gaps and propagate new design methods. Such an integrated process is paramount in maintaining U.S. leadership and in executing our national policy goals. The cross cutting process can take many forms, but all forms will have a positive affect on the demanding design environment through initial radical thinking. The author will illustrate such cross cutting results achievable through a formal process called FAST. The FAST example will be used to show how a multifunctional structural system concept for long duration spacecraft might be generated.
Recent cut damages to crewmember extravehicular mobility unit (EMU) gloves during extravehicular activity (EVA) onboard the International Space Station (ISS) has been found to result from contact with sharp edges or pinch points rather than general wear or abrasion. One possible source of cut-hazards are protruding sharp edged crater lips from impact of micrometeoroid and orbital debris (MMOD) particles on external metallic handrails along EVA translation paths. During impact of MMOD particles at hypervelocity an evacuation flow develops behind the shock wave, resulting in the formation of crater lips that can protrude above the target surface. In this study, two methods were evaluated to limit EMU glove cut-hazards due to MMOD impact craters. In the first phase, four flexible overwrap configurations are evaluated: a felt-reusable surface insulation (FRSI), polyurethane polyether foam with beta-cloth cover, double-layer polyurethane polyether foam with beta-cloth cover, and multi-layer beta-cloth with intermediate Dacron netting spacers. These overwraps are suitable for retrofitting ground equipment that has yet to be flown, and are not intended to protect the handrail from impact of MMOD particles, rather to act as a spacer between hazardous impact profiles and crewmember gloves. At the impact conditions considered, all four overwrap configurations evaluated were effective in limiting contact between EMU gloves and impact crater profiles. The multi-layer beta-cloth configuration was the most effective in reducing the height of potentially hazardous profiles in handrail-representative targets. In the second phase of the study, four material alternatives to current aluminum and stainless steel alloys were evaluated: a metal matrix composite, carbon fiber reinforced plastic (CFRP), fiberglass, and a fiber metal laminate. Alternative material handrails are intended to prevent the formation of hazardous damage profiles during MMOD impact and are suitable for flight hardware yet to be constructed. Of the four materials evaluated, only the fiberglass formed a less hazardous damage profile than the baseline metallic target. Although the CFRP laminate did not form any noticeable crater lip, brittle protruding fibers are considered a puncture risk. In parallel with EMU glove redesign efforts, modifications to metallic ISS handrails such as those evaluated in this study provide the means to significantly reduce cut-hazards from MMOD impact craters.
Recent cut damages sustained on crewmember gloves during extravehicular activity (ISS) onboard the International Space Station (ISS) have been caused by contact with sharp edges or a pinch point according to analysis of the damages. One potential source are protruding sharp edged crater lips from micrometeoroid and orbital debris (MMOD) impacts on metallic handrails along EVA translation paths. A number of hypervelocity impact tests were performed on ISS handrails, and found that mm-sized projectiles were capable of inducing crater lip heights two orders of magnitude above the minimum value for glove abrasion concerns. Two techniques were evaluated for mitigating the cut glove hazard of MMOD impacts on ISS handrails: flexible overwraps which act to limit contact between crewmember gloves and impact sites, and; alternate materials which form less hazardous impact crater profiles. In parallel with redesign efforts to increase the cut resilience of EMU gloves, the modifications to ISS handrails evaluated in this study provide the means to significantly reduce cut glove risk from MMOD impact craters
A device that enables the automated cutting and transfer of plant shoots is undergoing development for use in the propagation of plants in a nursery or laboratory. At present, it is standard practice for a human technician to use a knife and forceps to cut, separate, and grasp a plant shoot. The great advantage offered by the present device is that its design and operation are simpler than would be those of a device based on the manual cutting/separation/grasping procedure. [The present device should not be confused with a prior device developed for partly the same purpose and described in Compliant Gripper for a Robotic Manipulator (NPO-21104), NASA Tech Briefs, Vol. 27, No. 3 (March 2003), page 59.]. The device (see figure) includes a circular tube sharpened at its open (lower) end and mounted on a robotic manipulator at its closed (upper) end. The robotic manipulator simply pushes the sharpened open end of the tube down onto a bed of plants and rotates a few degrees clockwise then counterclockwise about the vertical axis, causing the tube to cut a cylindrical plug of plant material. Exploiting the natural friction between the tube and plug, the tube retains the plug, without need for a gripping mechanism and control. The robotic manipulator then retracts the tube, translates it to a new location over a plant-growth tray, and inserts the tube part way into the growth medium at this location in the tray. A short burst of compressed air is admitted to the upper end of the tube to eject the plug of plant material and drive it into the growth medium. A prototype has been tested and verified to function substantially as intended. It is projected that in the fully developed robotic plant-propagation system, the robot control system would include a machine- vision subsystem that would automatically guide the robotic manipulator in choosing the positions from which to cut plugs of plant material. Planned further development efforts also include more testing and refinement of the design and operation described above.
One of the high risk operations on the International Space Station (ISS) is conducting a space walk, or an Extra Vehicular Activity (EVA). Threats to the space walking crew include airlock failures, space suit failures, and strikes from micro ]meteoroids and orbital debris (MM/OD). There are risks of becoming untethered from the space station, being pinched between the robotic arm and a piece of equipment, tearing your suit on a sharp edge, and other human errors that can be catastrophic. For decades NASA identified and tried to control sharp edges on external structure and equipment by design; however a new and unexpected source of sharp edges has since become apparent. Until recently, one of the underappreciated environmental risks was damage to EVA gloves during a spacewalk. The ISS has some elements which have been flying in the environment of space for over 14 years. It has and continues to be bombarded with MM/OD strikes that have created small, sharp craters all over the structure, including the dedicated EVA handrails and surrounding structure. These craters are capable of cutting through several layers of the EVA gloves. Starting in 2006, five EVA crewmembers reported cuts in their gloves so large they rendered the gloves unusable and in some cases cut the spacewalk short for the safety of the crew. This new hazard took engineers and managers by surprise. NASA has set out to mitigate this risk to safety and operations by redesigning the spacesuit gloves to be more resilient and designing a clamp to isolate MM/OD strikes on handrails, and is considering the necessity of an additional tool to repair strikes on non ]handrail surfaces (such as a file). This paper will address how the ISS Risk Team quantified an estimate of the MM/OD damage to the ISS, and the resulting likelihood of sustaining a cut glove in order to measure the effectiveness of the solutions being investigated to mitigate this risk to the mission and crew.
A combined method of machining and applying a surface texture to a work piece and a tool assembly that is capable of machining and applying a surface texture to a work piece are disclosed. The disclosed method includes machining portions of an outer or inner surface of a work piece. The method also includes rotating the work piece in front of a rotating cutting tool and engaging the outer surface of the work piece with the rotating cutting tool to cut dimples in the outer surface of the work piece. The disclosed tool assembly includes a rotating cutting tool coupled to an end of a rotational machining device, such as a lathe. The same tool assembly can be used to both machine the work piece and apply a surface texture to the work piece without unloading the work piece from the tool assembly.
During operation, the PWR control rods are either completely extracted (scram or safety rods) or partially inserted in the operating zone of the core (fine control or operating rods). At the nominal rating conditions or close to them, the operating zone is limited to some steps of insertion in the order of a few tens of cm. In fact, only the lower part of the control rods are subjected to a significant neutron flux with an impact on the neutron activation and so on the waste classification (Low Level Short-lived Waste versus Intermediate Level Long-lived Waste). Our calculative as well as experimental experience confirms the significant presence of radionuclides in the control rods, but only in the lower parts. Measuring, cutting and finally sorting control rod scraps can reduce the volume of Intermediate Level Long-lived Waste planned for our storage deposit facility. This paper presents the EDF/DP2D methodologies followed to determine the sort criteria between the Low Level Short-lived Waste versus the Intermediate Level Long-lived Waste zones for the Silver-Indium-Cadmium control rods. The irradiated control rods are stored in cases without their head. Each case can contain several control rods, and the cases are stored under water in the fuel assembly pool. To calculate the radioactive inventories, we have developed a calculation scheme which is composed of a 3-dimensional mapping of the neutron flux, a calculation of the evolution of the isotopic compositions under neutron flux and finally a comparison between calculated and measured values. The main hypotheses of the control rods calculation take into account: - 3-dimensional geometry and 3-dimensional neutron sources distribution, - the isotopic compositions including impurities, - the history of irradiation resulting mainly from the daily power production, the positions of the control rods in the loading patterns and the positions in the axial operating zone. In order to validate the calculations, measurements were made 20 meters under water in the fuel assembly pool. The experimental results show the presence of many gamma emitter radionuclides. Only Ag-108m was retained for validating the calculations. This is due to the fact that silver is considered as the 'standard' chemical element for our control rods and silver produces Ag-108m which is a long-lived gamma emitter radionuclide. The analysis of the calculated results and the measured values allow us to build a simplified physics model for the simulation of the control rods activation. Finally three sort criteria can be proposed: - Without measurement devices, the sorting is based on an empirical sort criterion. Cuttings must then be made on the 2 back-ends of the control rod pins. This option is due to the difficulty in knowing the orientation of the pins in the storage cases. The cutting lines are placed at approximately 1 m from the 2 back-ends of the pins. This approach does not allow a great optimization of the sorting, less than 50% of the length of the control rods can be saved from Intermediate Level Long-lived Waste storage. - With a simple dose rate measurement device, the knowledge of the orientation of the pins in the storage cases allows us to limit cuttings to the lower part of the control rods. Depending on the 'top to tail' cases, between approximately 50% and 75% of the length of the control rods can be saved from Intermediate Level Long-lived Waste storage. - With an accurate measurement device, the sorting can be based on a specific activity of Ag-108m. Over 4400 Bq/g of Ag-108m (corresponding to the Intermediate Level Long-lived Waste limit), the control rod pieces can be considered as a long-lived waste. The measurements must be made over the 2 back-ends of control rod pins to examine the cases of 'top to tail' storage. This approach allows a great optimization of the sorting. Depending on the history of irradiation, more than 75% of the length of the control rods can be saved from Intermediate Level Long-lived Waste storage. (author)
Recently, various cutting and decontamination technologies for remote decommissioning works have been developed and applied. One of the technologies is a laser technology which has good capabilities for such kinds of works. Remote controllability is one of advantages of a laser system. Because in general the laser head is light and compact compared to the other types of cutting and decontamination tools, the head can be easily handled by remote operation equipment such as manipulators, and thus it gives an effective and flexible remote work. As the other examples of the advantages, there are no parts of a laser system necessary to be replaced so frequently like blades of mechanical methods and also, it does not generate secondary waste so much like contaminated water generated from water jet methods. Additionally, recent laser technology development has increased laser output power which makes it possible to be able to cut thick steel plate more smoothly and speedy, and width of laser irradiation which makes it possible to perform an efficient surface decontamination work. This paper will provide outline of the remote laser cutting system and decontamination system developed by IHI Corporation (IHI) and how those technologies are effective in various kinds of remote decommissioning works. (authors)
Magnox and TWI Ltd (TWI) have recently developed a first-of-a-kind automated remote laser cutting facility. The facility has been commissioned at Hinkley Point 'A' (HPA) nuclear power station and used to successfully demonstrate the capability of TWI's laser cutting technology to remotely size reduce contaminated Intermediate Level Waste (ILW) Magnox pond skips. The benefits of the facility include reduced cutting times, significantly reduced dose uptake, and significant cost savings. The facility has been designed with a 'plug-and-play' approach such that it could be de-planted and re-mobilised to another nuclear site for other applications. Three contaminated ILW Magnox pond skips with activities of 10.3, 25.1 and 218 GBq/t have been successfully size reduced with this facility; with less than 2.5 hours required to size reduce one skip, and the elapsed laser cutting time being less than 40 minutes. Subsequent radiological assessment showed that the surface contamination and airborne activity were confined within a specifically designed modular containment unit. Continuous real-time air monitoring results indicated a rapid rise and fall of airborne activity. The largest proportion of the airborne activity was removed from the modular containment within 10 minutes by local HEPA ventilation, with the residual activity taking approximately one hour to settle out entirely. The measured dose uptakes were mostly associated with manual handling of the skips to and from the size reduction facility, thus indicating the significance of an automated remote skip size reduction facility. This paper describes the design and performance of the laser skip size reduction facility and presents results of the radiological assessment for three contaminated skips with varying activities. (authors)