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1

Jupiter: Earth's Shield  

NSDL National Science Digital Library

Jupiter's immense gravity protects Earth from asteroids. In this video segment adapted from NOVA, scientists searching for signs of life in the universe identify solar systems with Jupiter-like planets that may be shielding smaller nearby Earth-like planets from comets and asteroids.

2005-12-17

2

Jupiter: Earth's Shield  

NSDL National Science Digital Library

More than 155 planets have been found outside of our solar system since the first discovery in 1995, mostly massive Jupiter-like planets in orbits close to their suns. Now, to find an Earth-like planet, scientists are looking for a planetary setup that is similar to our own, in which a Jupiter-like planet lies a good distance away from its sun. This video segment explores how the arrangement of planets in our solar system may have affected the development of life on Earth and describes how researchers are searching for the right planetary setup. The segment is two minutes one second in length. A background essay and list of discussion questions are also provided.

3

Reconnection: Solar Wind Breaches the Earths Magnetic Shield  

NSDL National Science Digital Library

The Far Ultraviolet camera abord the IMAGE spacecraft captured this view of a proton aurora (the bright spot near the center of the view) as well as the ring of the electron aurora. The protons for this aurora came from the incoming solar wind. The made it though the Earths magnetic shield in a magnetic reconnection event higher in the magnetosphere which was detected by the Cluster satellite. Note: A corner appears in the data in the beginning as the IMAGE spacecraft moves into a position where it can view the entire north polar region.

Bridgman, Tom; Frey, Harald; Phan, Tai

2003-12-04

4

THEMIS discovers holes in Earth's solar shield - Duration: 0:27.  

NASA Video Gallery

This animation shows the latest findings from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission. Earth's magnetic field; which shields our planet from severe ...

5

Numerical Simulation of Earth Pressure on Head Chamber of Shield Machine with FEM  

SciTech Connect

Model parameters of conditioned soils in head chamber of shield machine are determined based on tree-axial compression tests in laboratory. The loads acting on tunneling face are estimated according to static earth pressure principle. Based on Duncan-Chang nonlinear elastic constitutive model, the earth pressures on head chamber of shield machine are simulated in different aperture ratio cases for rotating cutterhead of shield machine. Relationship between pressure transportation factor and aperture ratio of shield machine is proposed by using aggression analysis.

Li Shouju; Kang Chengang [State Key Laboratory of structural analysis for industrial equipment, Dalian University of Technology, Dalian 116023 (China); Sun, Wei [School of Mechanical Engineering, Dalian University of Technology, Dalian 116023 (China); Shangguan Zichang [School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116023 (China); Institute of Civil Engineering, Dalian Fishery University, Dalian 116023 (China)

2010-05-21

6

On Reducing the Lightning Transients in Buried Shielded Cables Using Follow-On Earth Wire  

Microsoft Academic Search

This paper investigates the importance of a follow-on buried bare earth wire for the lightning protection of buried shielded cables. The use of follow-on bare wires for lightning protection of communication towers was suggested as a recommendation in certain standards, without being complemented either by theory or experiments. When lightning transients couple to the cable shields, it induces large currents

Nelson Theethayi; Rajeev Thottappillil

2007-01-01

7

How to protect the Earth from Global warming by means of Sunlight Shield Equipments  

NASA Astrophysics Data System (ADS)

The Earth is getting warmer because excess carbon dioxide of the Earth's atmosphere. Many studies are proceeding in the world in order to prevent global warming. Three methods are studied: (1) How to reduce carbon dioxide of the Earth's atmosphere. For example, more trees will be planted and carbon dioxide is changed to oxygen and carbon. (2) How to reduce carbon dioxide emission that human activity makes. (3) How to protect the Earth from global warming. The first or the second method has been studied, and they do not immediately protect the Earth from global warming. On the other hand the third method has an immediate effect. Sunlight shield effects of a cloud or tiny sulfur in the air have been studied. The author has proposed a sunlight shield equipment which is composed of a flat balloon. Balloon's surface has a mirror function. The sunlight shield equipment is set at the stratosphere and its surface reflects sunlight to the space. It is different temperature between daytime and night time, because the earth is heated by the sun during only daytime. Temperature of the Earth could be controlled by controlling an amount of a sunlight power which the earth receives from the sun. In other word, when many sunlight shield equipments are set and operated at the stratosphere, and an amount of sunlight, which the earth receives from the sun, could be controlled. For example, when an amount of the sunlight power, which the earth receives, decreases one percent, a mean value of the earth temperature deceases about one centigrade. In order to decrease one percent of a sunlight power which the earth receives, it is required that many sunlight shield equipments are distributively set and operated, and the gross area of many sunlight shield equipments is equal to 5,060,000 km squares. When a size of a sunlight shield equipment is equal to 5 km squares, about one million of sunlight shield equipments are necessary, and a large scale of cost is required. Therefore, an effective operation of sunlight shield equipments is desired. This paper clarifies how to operate effectively sunlight shield equipments in order to protect the Earth from global warming, and considers issues of the equipment operation.

Murakami, H.

2010-09-01

8

Magnetic shielding in a low temperature torsion pendulum experiment. [superconducting cylinders for attenuation earth field  

NASA Technical Reports Server (NTRS)

A new type of ether drift experiment searches for anomalous torques on a permanent magnet. A torsion pendulum is used at liquid helium temperature, so that superconducting cylinders can be used to shield magnetic fields. Lead shields attenuate the earth's field, while Nb-Sn shields fastened to the pendulum contain the fields of the magnet. The paper describes the technique by which the earth's field can be reduced below 0.0001 G while simultaneously the moment of the magnet can be reduced by a factor 7 x 10 to the 4th.

Phillips, P. R.

1979-01-01

9

Earth pressure balance (EPB) shield tunneling in Bangkok : ground response and prediction of surface settlements using artificial neural networks  

E-print Network

Although Earth Pressure Balance (EPB) shields have been used for several decades, very little information exists about the actual mechanisms of shield-ground interaction. The ground response mechanism induced by EPB tunneling ...

Suwansawat, Suchatvee, 1972-

2002-01-01

10

2. CONCRETE PADDING AREA BETWEEN BERM MOUNDS, LOOKING NORTH FROM ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. CONCRETE PADDING AREA BETWEEN BERM MOUNDS, LOOKING NORTH FROM TOP OF BERM. - NIKE Missile Base C-84, Acid Fueling Station, North of Launch Area Entrance Drive, eastern central portion of base, Barrington, Cook County, IL

11

SPERTI Reactor Pit Building (PER605). Earth shielding protect adjacent Instrument ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

SPERT-I Reactor Pit Building (PER-605). Earth shielding protect adjacent Instrument Cell (PER-606). Security fencing surrounds complex, to which gate entry is provided next to Guard House (PER-607). Note gravel road leading to control area. Earth-covered conduit leads from instrument cell to terminal building out of view. Photographer: R.G. Larsen. Date: June 22, 1955. INEEL negative no. 55-1701 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

12

A captured asteroid : Our David's stone for shielding earth and providing the cheapest extraterrestrial material  

NASA Astrophysics Data System (ADS)

The issue of protecting the Earth against an asteroid impact is very popular and many concepts have been proposed to fulfil this objective. In this paper, we develop the idea of capturing a small size asteroid from an orbit close to Earth's in terms of energy and placing it into a loose Earth-bound orbit in order to use it as a shield by engineering its collision with any incoming, threatening body prior to its impact with the Earth. The operations for turning the captured asteroid into an efficient shield appear to be quicker, easier, cheaper and safer than an mission aimed at landing on an incoming impact-bound asteroid either for altering its trajectory or attempting to destroy it. The aim is an asteroid typically 20 40 m in diameter, too small to cause damage on Earth if an improper management leads to its crash, but big enough to destroy and deviate any incoming body if a collision is engineered with it preferably at more than one million km from Earth. Such a collision could be implemented within a 8 month time frame. Such an asteroid would also be a source of material such as liquid oxygen for exploratory missions. We show that the production of this material is much more efficient from an asteroid's surface than from the Moon's. As the celestial surface most accessible from Earth, a captured asteroid is also easier to engineer. Several thousands of tons of oxygen might become available sitting on the outer rim of Earth's gravity field. We examine the advantages and drawbacks of this concept and we propose a stepped approach for making it a reality within a foreseeable future. Key factors are first the detection of a candidate, whose small size make it difficult to spot, among a population of asteroids easy to reach from the Earth. We have identified such a potential candidate in 2000SG344 and describe the parameters of its capture. The second key point is how to deviate the candidate into an loose Earth bound orbit. Our preferred concept is to deposit a small robotic instrument aimed at throwing up matter gathered on the surface of the body with typical velocities of tens of meters per second. The robot would require a year and a few hundreds of watts continuously to alter the velocity of the asteroid in such a way as to inject it through an Earth Sun Lagrange point, and then to control a Lagrangian quasi-periodic orbit with a typical 6-month period. We conclude that such an enterprise is far from being unfeasible and that it can probably be conducted using today's systems and exploratory tools in a few years time frame.

Massonnet, Didier; Meyssignac, Benoît

2006-07-01

13

Using Combustion Synthesis to Reinforce Berms and Other Regolith Structures  

NASA Technical Reports Server (NTRS)

The Moonraker Excavator and other tools under development for use on the Moon, Mars, and asteroids will be employed to construct a number of civil engineering projects and to mine the soil. Mounds of loose soil will be subject to the local transport mechanisms plus artificial mechanisms such as blast effects from landers and erosion from surface vehicles. Some of these structures will require some permanence, with a minimum of maintenance and upkeep. Combustion Synthesis (CS) is a family of processes and techniques whereby chemistry is used to transform materials, often creating flame in a hard vacuum. CS can be used to stabilize civil engineering works such as berms, habitat shielding, ramps, pads, roadways, and the like. The method is to unroll thin sheets of CS fabric between layers of regolith and then fire the fabric, creating a continuous sheet of crusty material to be interposed among layers of loose regolith. The combination of low-energy processes, ISRU (in situ resource utilization) excavator, and CS fabrics, seems compelling as a general method for establishing structures of some permanence and utility, especially in the role of robotic missions as precursors to manned exploration and settlement. In robotic precursory missions, excavator/ mobility ensembles mine the Lunar surface, erect constructions of soil, and dispense sheets of CS fabrics that are covered with layers of soil, fired, and then again covered with layers of soil, iterating until the desired dimensions and forms are achieved. At the base of each berm, for example, is a shallow trench lined with CS fabric, fired and filled, mounded, and then covered and fired, iteratively to provide a footing against lateral shear. A larger trench is host to a habitat module, backfilled, covered with fabric, covered with soil, and fired. Covering the applied CS fabric with layers of soil before firing allows the resulting matrix to incorporate soil both above and below the fabric ply into the fused layer, developing a very irregular surface which, like sandpaper, can provide an anchor for loose soil. CS fabrics employ a coarse fiberglass weave that persists as reinforcement for the fired material. The fiberglass softens at a temperature that exceeds the combustion temperature by factors of two to three, and withstands the installation process. This type of structure should be more resistant to rocket blast effects from Lunar landers.

Rodriquez, Gary

2013-01-01

14

One dimensional modeling of anthropogenic beach berm erosion  

NASA Astrophysics Data System (ADS)

Anthropogenic beach berms (sometimes called artificial berms or artificial dunes) are in use internationally to guard against beach overtopping and consequent coastal flooding. Berms can be constructed on a seasonal basis or in anticipation of a hazardous event, e.g., when a storm is expected to arrive coincident with an astronomical high tide. In either case, a common approach is to scrape sand from the foreshore with heavy equipment and deposit it on the crest of the natural beach dune, thus providing added protection from the possibility of wave overtopping. Given the potential for higher sea levels globally and more extreme storm events, anthropogenic berms will surely be tested to their limits and will ultimately fail, causing flooding. A better understanding of the conditions under which these berms fail is therefore needed to support coastal flood risk management. An experimental campaign in Newport Beach, California was conducted to document the dynamic erosion of prototype beach berms under a rising tide and mild to moderate wave conditions. Terrestrial laser scanning (TLS) of the berm produced a digital model of how the berm shape evolved over time. Here, a numerical model of swash zone hydromorphodynamics based on shallow-water flow physics is presented to evaluate whether and to what extent the timing and degree of berm erosion and overtopping can be predicted from first principles. The model tightly couples flow and sediment transport within an approximate Riemann solver, and thus is of the Godunov-type variety of finite volume schemes. Additionally, the model includes an avalanching scheme to account for non-hydrodynamic slumping down the angle of repose. Results indicate that it is possible to calibrate the model for a particular event, and then successfully predict erosion for another event, but due to parameter sensitivities, it is unlikely that the model can be applied at a site without calibration (true prediction).

Shakeri Majd, M.; Sanders, B. F.

2013-12-01

15

Development of Multifunctional Radiation Shielding Materials for Long Duration Human Exploration Beyond the Low Earth Orbit  

NASA Technical Reports Server (NTRS)

One of the major challenges for long duration human exploration beyond the low Earth orbit and sustained human presence on planetary surfaces would be development of materials that would help minimize the radiation exposure to crew and equipment from the interplanetary radiation environment, This radiation environment consists primarily of a continuous flux of galactic cosmic rays (GCR) and transient but intense fluxes of solar energetic particles (SEP). The potential for biological damage by the relatively low percentage of high-energy heavy-ions in the GCR spectrum far outweigh that due to lighter particles because of their ionizing-power and the quality of the resulting biological damage. Although the SEP spectrum does not contain heavy ions and their energy range is much lower than that for GCRs, they however pose serious risks to astronaut health particularly in the event of a bad solar storm The primary purpose of this paper is to discuss our recent efforts in development and evaluation of materials for minimizing the hazards from the interplanetary radiation environment. Traditionally, addition of shielding materials to spacecrafts has invariably resulted in paying a penalty in terms of additional weight. It would therefore be of great benefit if materials could be developed not only with superior shielding effectiveness but also sufficient structural integrity. Such a multifunctional material could then be considered as an integral part of spacecraft structures. Any proposed radiation shielding material for use in outer space should be composed of nuclei that maximize the likelihood of projectile fragmentation while producing the minimum number of target fragments. A modeling based approach will be presented to show that composite materials using hydrogen-rich epoxy matrices reinforced with polyethylene fibers and/or fabrics could effectively meet this requirement. This paper will discuss the fabrication of such a material for a crewed vehicle. Ln addition, the capability of synthesizing radiation shielding materials for habitat structures primarily from Lunar or Martian in-situ resources will also be presented. Such an approach would significantly _reduce the cost associated with transportation of such materials and structures from earth. Results from radiation exposure measurements will be presented demonstrating the shielding effectiveness of the developed materials. Mechanical testing data will be discussed to illustrate that the specific mechanical properties of the developed composites are comparable to structural aluminum based alloys currently used for the space shuttle and space station.

Sen, S.; Bhattacharya, M.; Schofield, E.; Carranza, S.; O'Dell, S.

2007-01-01

16

3. EAST ELEVATION, SHOWING RAISED APRON BERM IN FOREGROUND. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. EAST ELEVATION, SHOWING RAISED APRON BERM IN FOREGROUND. - Loring Air Force Base, Double Cantilever Hangar, East of Arizona Road, west of southern portion of Taxiway J, Limestone, Aroostook County, ME

17

7. Water treatment plant, view to E, berm in foreground ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. Water treatment plant, view to E, berm in foreground covering settling tank - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

18

5. Water treatment plant, view to N, berm in foreground ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. Water treatment plant, view to N, berm in foreground - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

19

8. Water treatment plant, view to SE, berm in foreground ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. Water treatment plant, view to SE, berm in foreground covering settling tank - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

20

4. Water treatment plant, view to NW, berm in foreground ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. Water treatment plant, view to NW, berm in foreground - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

21

6. Water treatment plant, view NE, berm in foreground ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. Water treatment plant, view NE, berm in foreground - Fort Benton Water Treatment Plant, Filtration Plant, Lots 9-13 of Block 7, Fort Benton Original Townsite at Missouri River, Fort Benton, Chouteau County, MT

22

1. BERMED AREA, LOOKING FROM SILO 'O' POSITION, NORTHWEST. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. BERMED AREA, LOOKING FROM SILO 'O' POSITION, NORTHWEST. - NIKE Missile Base C-84, Acid Fueling Station, North of Launch Area Entrance Drive, eastern central portion of base, Barrington, Cook County, IL

23

3. CONCRETE FORMATIONS IN LOWER AREA BETWEEN BERMS, LOOKING SOUTHEAST. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. CONCRETE FORMATIONS IN LOWER AREA BETWEEN BERMS, LOOKING SOUTHEAST. - NIKE Missile Base C-84, Acid Fueling Station, North of Launch Area Entrance Drive, eastern central portion of base, Barrington, Cook County, IL

24

17. View from Sterling Creek Marsh looking west, with berm ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

17. View from Sterling Creek Marsh looking west, with berm to the left and Henry Ford Mansion in the far background - Richmond Hill Plantation, Sterling Creek Marsh, East of Richmond Hill on Ford Neck Road, Richmond Hill, Bryan County, GA

25

BLDG 250, OVERVIEW SHOWING BERMS AND BLAST WALLS. Naval ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

BLDG 250, OVERVIEW SHOWING BERMS AND BLAST WALLS. - Naval Magazine Lualualei, Headquarters Branch, Ammo Rework-Overhaul Building, Forty-second Street between Jamestown & Iwo Jima Streets, Pearl City, Honolulu County, HI

26

65. SOUTH PLANT CHEMICAL STORAGE TANKS, WITH SECONDARY CONTAINMENT BERM ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

65. SOUTH PLANT CHEMICAL STORAGE TANKS, WITH SECONDARY CONTAINMENT BERM IN FOREGROUND. VIEW TO NORTHEAST. - Rocky Mountain Arsenal, Bounded by Ninety-sixth Avenue & Fifty-sixth Avenue, Buckley Road, Quebec Street & Colorado Highway 2, Commerce City, Adams County, CO

27

FEATURE A. CONCRETE ANTIAIRCRAFT GUN POSITION, SHOWING CORAL RUBBLE BERM, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

FEATURE A. CONCRETE ANTI-AIRCRAFT GUN POSITION, SHOWING CORAL RUBBLE BERM, VIEW FACING SOUTHEAST. - Naval Air Station Barbers Point, Battery-Anti-Aircraft Gun Position, South of Point Cruz Road & west of Coral Sea Road, Ewa, Honolulu County, HI

28

Organ shielding and doses in Low-Earth orbit calculated for spherical and anthropomorphic phantoms  

NASA Astrophysics Data System (ADS)

Humans in space are exposed to elevated levels of radiation compared to ground. Different sources contribute to the total exposure with galactic cosmic rays being the most important component. The application of numerical and anthropomorphic phantoms in simulations allows the estimation of dose rates from galactic cosmic rays in individual organs and whole body quantities such as the effective dose. The male and female reference phantoms defined by the International Commission on Radiological Protection and the hermaphrodite numerical RANDO phantom are voxel implementations of anthropomorphic phantoms and contain all organs relevant for radiation risk assessment. These anthropomorphic phantoms together with a spherical water phantom were used in this work to translate the mean shielding of organs in the different anthropomorphic voxel phantoms into positions in the spherical phantom. This relation allows using a water sphere as surrogate for the anthropomorphic phantoms in both simulations and measurements. Moreover, using spherical phantoms in the calculation of radiation exposure offers great advantages over anthropomorphic phantoms in terms of computational time. In this work, the mean shielding of organs in the different voxel phantoms exposed to isotropic irradiation is presented as well as the corresponding depth in a water sphere. Dose rates for Low-Earth orbit from galactic cosmic rays during solar minimum conditions were calculated using the different phantoms and are compared to the results for a spherical water phantom in combination with the mean organ shielding. For the spherical water phantom the impact of different aluminium shielding between 1 g/cm2 and 100 g/cm2 was calculated. The dose equivalent rates were used to estimate the effective dose rate.

Matthiä, Daniel; Berger, Thomas; Reitz, Günther

2013-08-01

29

A near-earth optical communications terminal with a corevolving planetary sun shield  

NASA Technical Reports Server (NTRS)

The umbra of a planet may serve as a sun shield for a space based optical communications terminal or for a space based astronomical observatory. An orbit that keeps the terminal or observatory within the umbra is desirable. There is a corevolution point behind every planet. A small body stabilized at the planet corevolution point will revolve about the sun at the same angular velocity as the planet, always keeping the planet between itself and the sun. This corevolution point is within the umbra of Mars but beyond the end of the umbra for Mercury, Venus, and earth. The Mars corevolution point is an ideal location for an astronomical observatory. There Mars obstruct less than 0.00024 percent of the sky at any time, and it shades the observatory completely from the sun. At the earth corevolution point, between 51 and 84 percent of the solar disk area is blocked, as is up to 92 percent of the sunlight. This provides a reduction from 3 dB to 11 dB in sunlight that could interfere with optical communications if scattered directly into the detectors. The variations is caused by revolution of the earth about the earth-moon barycenter.

Kerr, E. L.

1987-01-01

30

A near-earth optical communications terminal with a corevolving planetary sun shield  

NASA Technical Reports Server (NTRS)

The umbra of a planet may serve as a sun shield for a space-based optical communications terminal or for a space-based astronomical observatory. An orbit that keeps the terminal or observatory within the umbra is desirable. There is a corevolution point behind every planet. A small body stabilized at the planet corevolution point will revolve about the sun at the same angular velocity as the planet, always keeping the planet between itself and the sun. This corevolution point is within the umbra of Mars but beyond the end of the umbra for Mercury, Venus, and earth. The Mars corevolution point is an ideal location for an astronomical observatory. There, Mars obstruct less than 0.00024 percent of the sky at any time, and it shades the observatory completely from the sun. At the earth corevolution point, between 51 and 84 percent of the solar disk area is blocked, as is up to 92 percent of the sunlight. This provides a reduction from 3 dB to 11 dB in sunlight that could interfere with optical communications if scattered directly into the detectors. The variations is caused by revolution of the earth about the earth-moon barycenter.

Kerr, E. L.

1989-01-01

31

UV shielding of early Earth by N2/CH4/CO2 organic haze  

NASA Astrophysics Data System (ADS)

There is evidence that the atmosphere of the early Earth did not contain enough carbon dioxide to warm the surface in the epoch of the faint young Sun (Rye et al. 1995). Current suggestions focus on an additional greenhouse effect of methane (Pavlov et al. 2000). However, methane and ammonia, both strong greenhouse gases, are destroyed by UV light. Sagan and Chyba (1997) proposed that the early Earth had an organic haze layer produced, as on Titan, by methane photolysis in the presence of nitrogen. Such a layer would preferentially absorb ultraviolet light, thereby allowing ammonia and methane to persist in the atmosphere. However, as in the case of Titan, such a layer would also have an antigreenhouse effect (McKay et al. 1999) which could oppose or even cancel any greenhouse effect generated by the shielded methane and ammonia. The question of whether a combination of an organic haze layer and methane and ammonia gases can combine to produce a net greenhouse effect on the early Earth depends on the optical properties of the organic haze layer. We have produced organic material (tholin) simulating a methane photochemical haze in a CO_2-rich atmosphere of the early Earth by irradiating gas mixtures in an inductively coupled cold plasma chamber at a pressure of 0.26 mbar. We added progressively higher levels of CH_4 by combining gas mixtures of N_2/CH_4 (9/1) and N_2/CO_2 (9/1) to change the ratio of CH_4/CO_2. Tholin was accumulated for 5 hours in each experiment; the onset of tholin formation is around CH_4/CO_2 ? 0.5. As the mixing ratio of CH_4 is increased, the production rate of the brownish tholin film increases. IR spectra showed the C-H and N-H bands similar to that of Titan tholin. A decrease in the C-H bonds on decreasing CH_4/CO_2 is noted. Ether bands (C-O-C) were tentatively detected, but no detectable carbonyl (C=O) band was found. The absorption in the UV region for the early Earth tholin is found to be greater than the Titan tholin. The slopes of the optical properties suggest that a UV shielding by the early Earth tholin would be less efficient than those of Titan tholin.

Imanaka, H.; Khare, B. N.; McKay, C. P.

32

Canmar's berm-supported SSDC drilling advances arctic technology  

SciTech Connect

This report describes design, installation and performance of the single steel drilling caisson (SSDC) on a subsea berm. It details key points learned from the $100-million project by Canadian Marine Drilling Ltd. installed in the Beaufort Sea. Unitized construction allows for permanent installation and hookup of the drilling rig package. Mobilization and demobilization is much simpler, resulting in quicker and safer operation than that required with a multi-caisson system. The high freeboard achieved with the SSDC unit gives much greater protection with respect to wave run-up and ice ride-up, resulting in significant operational improvements. The relatively low elevation of the submerged berm at 9 m below sea level results in improved berm stability and erosion resistance.

Hewitt, K.J.; Berzins, W.E.; Fitzpatrick, J.P.; Hogeboom, H.G.

1985-07-01

33

First Year Sedimentological Characteristics and Morphological Evolution of an Artificial Berm at Fort Myers Beach, Florida  

E-print Network

First Year Sedimentological Characteristics and Morphological Evolution of an Artificial Berm Methods and Data Analysis 29 Results and Discussion 34 Sedimentological Characteristics of the Artificial Project Area 45 Control Area Northwest of Berm 47 Discussion of Sedimentological Characteristics 49

US Army Corps of Engineers

34

A captured asteroid : Our David's stone for shielding earth and providing the cheapest extraterrestrial material  

Microsoft Academic Search

The issue of protecting the Earth against an asteroid impact is very popular and many concepts have been proposed to fulfil this objective. In this paper, we develop the idea of capturing a small size asteroid from an orbit close to Earth's in terms of energy and placing it into a loose Earth-bound orbit in order to use it as

Didier Massonnet; Benoît Meyssignac

2006-01-01

35

Runoff and Sediment Transport from Compost Mulch Berms on a Simulated Military Training Landscape  

Microsoft Academic Search

Soil erosion and runoff due to mechanical disturbances on military training ranges can cause problems such as land degradation and environmental pollution of downstream ecosystems. This paper discusses runoff and sediment transport from compost mulch berms on a simulated military training landscape. The berms were constructed using mixtures of municipal yard waste (YW), wood chips (WC), pine bark fines (PB),

E. Z. Nyakatawa; D. A. Mays; H. R. Howard; N. G. Svendsen; R. Britton; R. O. Pacumbaba Jr

2010-01-01

36

Debris Basin and Deflection Berm Design for Fire-Related Debris-Flow Mitigation  

E-print Network

of a debris flow. Deflection berms are open structures that are designed to direct debris flows toward lowDebris Basin and Deflection Berm Design for Fire-Related Debris-Flow Mitigation ADAM B. PROCHASKA1 Engineering, 1516 Illinois Street, Golden, CO 80401 Key Terms: Debris Flow, Fire-Related, Mitigation, Design

37

Potential of Ozone Formation by the Smog Mechanism to shield the surface of the Early Earth from UV radiation?  

E-print Network

We propose that the photochemical smog mechanism produced substantial ozone (O3) in the troposphere during the Proterozoic, which contributed to ultraviolet (UV) radiation shielding hence favoured the establishment of life. The smog mechanism is well-established and is associated with pollution hazes which sometimes cover modern cities. The mechanism proceeds via the oxidation of volatile organic compounds (VOCs) such as methane (CH4) in the presence of UV radiation and nitrogen oxides (NOx). It would have been particularly favoured during the Proterozoic given the high levels of CH4 (up to 1000 ppm) recently suggested. Proterozoic UV levels on the surface of the Earth were generally higher compared with today, which would also have favoured the mechanism. On the other hand, Proterozoic O2 required in the final step of the smog mechanism to form O3 was less abundant compared with present times. Further, results are sensitive to Proterozoic NOx concentrations, which are challenging to predict, since they depen...

Grenfell, J L; Patzer, B; Titz, R; Rauer, H; Grenfell, John Lee; Stracke, Barbara; Patzer, Beate; Titz, Ruth; Rauer, Heike

2006-01-01

38

BLDG 250, FROM BERM/BLAST WALL ON NORTH SIDE OF BLDG. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

BLDG 250, FROM BERM/BLAST WALL ON NORTH SIDE OF BLDG. - Naval Magazine Lualualei, Headquarters Branch, Ammo Rework-Overhaul Building, Forty-second Street between Jamestown & Iwo Jima Streets, Pearl City, Honolulu County, HI

39

Progress Toward Electrostatic Radiation Shielding of Interplanetary Spacecraft: Strategies, Concepts and Technical Challenges of Human Exploration Beyond Low Earth Orbit  

NASA Technical Reports Server (NTRS)

The radiation problem is a serious obstacle to solar system exploration. Electrostatic shielding was previously dismissed as unworkable. This was based on the false assumption that radial symmetry is needed to provide isotropic protection. KSC recently demonstrated the feasibility of asymmetric, multipole electrostatic shielding. Combined with passive shielding it might solve the radiation problem

Metzger, Philip T.; Lane, John E.; Youngquist, Robert C.

2004-01-01

40

Reconstruction of the ancient zones of stress relaxation in the Earth's crust of the north-eastern Baltic Shield.  

NASA Astrophysics Data System (ADS)

The research has been carried out on the basis of numerical simulation to reconstruct zones of high permeability of the basement, which formed in the Early Precambrian and determined the localization of tectonic and magmatic processes in the region. The study region is treated as a non-uniform elastic body affected by volume forces and stresses specified at the boundary. Three stages of the region development have been studied: (a) 3.0-2.8 Ga; (b) 2.8 - 2.5 Ga; (c) 2.5-1.6 Ga. At each stage a base model has been set. Every model describes the studied region in terms of geological structures formed by this time. Linear-elastic constants for rocks and direction of the compressive forces were specified in accordance with the available data. Performed investigation allowed to estimate stress values which could occur in the continental plate of the northeastern Baltic Shield by external tectonic forces. Quantitative models of the stress and strain state of the regional Earth's crust have been constructed with due regard of its evolution. It is proposed to apply calculations of maximum shear stress when identifying weak zones. The permeable zones of the crust are marked by anomalous values of shear stresses. Almost all tracing zones coincide with the areas, where tectonic and magmatic processes have performed. All marked zones are correlated with the known Archaean and Proterozoic and Palaeozoic geologic structures. The obtained results revealed a location heredity of magma feeding channels in the region from the Archaean up to the Early Proterozoic and Palaeozoic. Thus, the stress and strain state could affect the character of the geodynamic processes that determined the development of the mobile-permeable zones within the rigid blocks. The carried out investigation pioneers quantitative estimates and interrelation of geodynamic factors interpreting formation mechanisms of the deformed structures in the region. The obtained results give grounds to revise the existing concepts about the mechanism of the Earth's crust formation in the north-eastern Baltic Shield. The elaborated methods can be applied for fast diagnosis to allocate weakened zones in the basement and evaluate their permeability degree with the minimum time and resources required.

Filatova, Valentina

2014-05-01

41

Potential of Ozone Formation by the Smog Mechanism to shield the surface of the Early Earth from UV radiation?  

E-print Network

We propose that the photochemical smog mechanism produced substantial ozone (O3) in the troposphere during the Proterozoic, which contributed to ultraviolet (UV) radiation shielding hence favoured the establishment of life. The smog mechanism is well-established and is associated with pollution hazes which sometimes cover modern cities. The mechanism proceeds via the oxidation of volatile organic compounds (VOCs) such as methane (CH4) in the presence of UV radiation and nitrogen oxides (NOx). It would have been particularly favoured during the Proterozoic given the high levels of CH4 (up to 1000 ppm) recently suggested. Proterozoic UV levels on the surface of the Earth were generally higher compared with today, which would also have favoured the mechanism. On the other hand, Proterozoic O2 required in the final step of the smog mechanism to form O3 was less abundant compared with present times. Further, results are sensitive to Proterozoic NOx concentrations, which are challenging to predict, since they depend on uncertain quantities such as NOx source emissions and OH concentrations. We review NOx sources during the Proterozoic and apply a photochemical box model having methane oxidation with NOx, HOx and Ox chemistry to estimate the O3 production from the smog mechanism. Runs suggest the smog mechanism during the Proterozoic can produce about double present day ozone columns for NOx levels of 1.53 10-9 by volume mixing ratio, which was attainable according to our NOx source analysis, with 1 per-cent present atmospheric levels (PALs) of O2. Clearly, forming ozone in the troposphere is a trade-off for survivability. On the one hand harmful UV is blocked, but on the other hand ozone is a respiratory irratant, which becomes fatal at concentrations exceeding about 1 ppmv.

John Lee Grenfell; Barbara Stracke; Beate Patzer; Ruth Titz; Heike Rauer

2006-09-08

42

Advanced Multifunctional MMOD Shield: Radiation Shielding Assessment  

NASA Technical Reports Server (NTRS)

As NASA is looking to explore further into deep space, multifunctional materials are a necessity for decreasing complexity and mass. One area where multifunctional materials could be extremely beneficial is in the micrometeoroid orbital debris (MMOD) shield. A typical MMOD shield on the International Space Station (ISS) is a stuffed whipple shield consisting of multiple layers. One of those layers is the thermal blanket, or multi-layer insulation (MLI). By increasing the MMOD effectiveness of MLI blankets, while still preserving their thermal capabilities, could allow for a less massive MMOD shield. Thus, a study was conducted to evaluate concept MLI blankets for MMOD shields. In conjunction, these MLI blankets and the subsequent MMOD shields were also evaluated for their radiation shielding effectiveness towards protecting crew. These concepts were evaluated against the ISS MLI blankets and the ISS MMOD shield, which acted as the baseline. These radiation shielding assessments were performed using the high charge and energy transport software (HZETRN). This software is based on a one-dimensional formula of the Boltzmann transport equation with a straight-ahead approximation. Each configuration was evaluated against the following environments to provide a diverse view of radiation shielding effectiveness in most space environments within the heliosphere: August 1972 solar particle event, October 1989 solar particle event, 1982 galactic cosmic ray environment (during solar maximum), 1987 galactic cosmic ray environment (during solar minimum), and a low earth orbit environment in 1970 that corresponded to an altitude of 400 km and inclination of 51.6 . Both the absorbed dose and the dose equivalent were analyzed, but the focus of the discussion was on the dose equivalent since the data is most concerned with radiation shielding of the crew. The following paper outlines the evaluations performed and discusses the results and conclusions of this evaluation for radiation shielding effectiveness. Future work will focus on optimizing the radiation shielding properties for the MMOD shield. Submission

Rojdev, Kristina; Christiansen, Eric

2011-01-01

43

Evidence for the Snowball Earth hypothesis in the Arabian-Nubian Shield and the East African Orogen  

NASA Astrophysics Data System (ADS)

Formation of the Arabian-Nubian Shield (ANS) and the East African Orogen (EAO) occurred between 870 Ma and the end of the Precambrian (˜542 Ma). ANS crustal growth encompassed a time of dramatic climatic change, articulated as the Snowball Earth hypothesis (SEH). SEH identifies tremendous paleoclimatic oscillations during Neoproterozoic time. Earth’s climate shifted wildly, from times when much of our planet’s surface was frozen to unusually warm episodes and back again. There is evidence for four principal icehouse episodes: ˜585 582 Ma (Gaskiers), ˜660 635 Ma (Marinoan), ˜680 715 Ma (Sturtian), and ˜735 770 Ma (Kaigas). Evidence consistent with the SEH has been found at many locations around the globe but is rarely reported from the ANS, in spite of the fact that this may be the largest tract of Neoproterozoic juvenile crust on the planet, and in spite of the fact that Huqf Group sediments in Oman, flanking the ANS, record evidence for Sturtian and Marinoan low-latitude glaciations. This review identifies the most important evidence preserved in sedimentary rocks elsewhere for SEH: diamictites, dropstones, cap carbonates, and banded iron formation (BIF). Expected manifestations of SEH are integrated into our understanding of ANS and EAO tectonic evolution. If Kaigas and Sturtian events were global, sedimentary evidence should be preserved in ANS sequences, because these occurred during an embryonic stage of ANS evolution, when crustal components (island arcs, back-arc basins, and sedimentary basins) were mostly below sea level. Previous SEH investigations have been largely reconnaissance in scope, but potentially diagnostic sedimentary units such as diamictites, marine carbonates with ?13C excursions and banded iron formations are reported from the ANS and are worthy of further investigation. Collision and uplift to form the EAO destroyed most marine sedimentary basins about 630 Ma ago, so evidence of Marinoan and Gaskiers glaciations will be more difficult to identify. Several post-accretionary Neoproterozoic sedimentary basins in Arabia may preserve sedimentary evidence but such evidence has not been documented yet. The Huqf Group of Oman contains sedimentary evidence for the Marinoan glaciation but no evidence that the Gaskiers glaciation was significant in this part of the world. Deep erosion at ˜600 Ma throughout the northern ANS and EAO may be related to Marinoan continental glaciation, which may have accomplished much of the cutting of the ANS peneplain, but final shaping of the peneplain took place over the next 60 million years. African geoscientists can contribute to our understanding of Neoproterozoic climate change through careful field studies, and the international geoscientific community interested in Neoproterozoic climate change should pay attention to evidence from the ANS. Future investigations should include knowledge of the SEH and its controversial aspects, in addition to the greater plate tectonic setting of the ANS.

Stern, R. J.; Avigad, D.; Miller, N. R.; Beyth, M.

2006-01-01

44

Shielding Strategies for Human Space Exploration  

Microsoft Academic Search

The shield effectiveness of lunar regolith is compared with possible prefabricated shield materials from Earth,including commercially used shield materials in nuclear facilities. Several of the fabricated materials categorized asneutron absorbers and moderators exhibit favorable characteristics for space radiation protection. Although thiseffort is not intended to be a definitive trade study for specific shielding recommendations, attention is given toseveral factors that

J. W. Wilson; J. Miller; A. Konradi; F. A. Cucinotta

1997-01-01

45

Re: Report has been approved: Effects of Building a Sand Barrier Berm to Mitigate the Effects of the Deepwater Horizon Oil Spill on Louisiana Marshes  

E-print Network

of the Deepwater Horizon Oil Spill on Louisiana Marshes t Judy J Nowakowski 0 Jess 0 Weaver c . Barbara W Wainman a Sand Barrier Berm to Mitigate the Effects of the Deepwater Horizon Oil Spill on Louisiana Marshes of Building a Sand Barrier Berm to Mitigate the Effects of the Deepwater Horizon Oil Spill on Louisiana

Torgersen, Christian

46

Earth  

NASA Technical Reports Server (NTRS)

The following aspects of the planet Earth are discussed: plate tectonics, the interior of the planet, the formation of the Earth, and the evolution of the atmosphere and hydrosphere. The Earth's crust, mantle, and core are examined along with the bulk composition of the planet.

Carr, M. H.

1984-01-01

47

Shield tunneling method and machine therefor  

Microsoft Academic Search

A method is disclosed for excavating a tunnel wherein the muck from the tunnel face is admitted into the shield; the muck is pressed by a pressure of a predetermined level higher than an active earth pressure in the face and lower than a passive earth pressure as the shield body is moved forward, thereby establishing the balance between the

Akesaka

1983-01-01

48

Shielded, Automated Umbilical Mechanism  

NASA Technical Reports Server (NTRS)

Umbilical mechanism automatically connects and disconnects various fluid couplings and/or electrical contacts while shielding mating parts from debris. Reacts mating and demating loads internally, without additional supporting structures. All functions - extension of plug, mating, and movement of debris shields - actuated by single motor. If mechanism jams or fails at any point in sequence, override feature in drive train allows manual operation. Designed for service in outer space, where its shields protect against micrometeoroids, debris, ultraviolet radiation, and atomic oxygen. Used on Earth to connect or disconnect fluid or electrical utilities in harsh environments like those of nuclear powerplants or undersea construction sites, or in presence of radioactive, chemical, or biological hazards, for example.

Barron, Daniel R.; Morrill, Brion F.; Jasulaitis, Vytas

1995-01-01

49

Towards improved prediction and mitigation of beach overwash: Terrestrial LiDAR observation of dynamic beach berm erosion  

NASA Astrophysics Data System (ADS)

Globally, over 20 million people currently reside below high tide levels and 200 million are below storm tide levels. Future climate change along with the pressures of urbanization will exacerbate flooding in low lying coastal communities. In Southern California, coastal flooding is triggered by a combination of high tides, storm surge, and waves and recent research suggests that a current 100 year flood event may be experienced on a yearly basis by 2050 due to sea level rise adding a positive offset to return levels. Currently, Southern California coastal communities mitigate the threat of beach overwash, and consequent backshore flooding, with a combination of planning and operational activities such as protective beach berm construction. Theses berms consist of temporary alongshore sand dunes constructed days or hours before an extreme tide or wave event. Hydraulic modeling in urbanized embayments has shown that coastal flooding predictions are extremely sensitive to the presence of coastal protective infrastructure, requiring parameterization of the hard infrastructure elevations at centimetric accuracy. Beach berms are an example of temporary dynamic structures which undergo severe erosion during extreme events and are typically not included in flood risk assessment. Currently, little is known about the erosion process and performance of these structures, which adds uncertainty to flood hazard delineation and flood forecasts. To develop a deeper understanding of beach berm erosion dynamics, three trapezoidal shaped berms, approximately 35 m long and 1.5 m high, were constructed and failure during rising tide conditions was observed using terrestrial laser scanning. Concurrently, real-time kinematic GPS, high-definition time lapse photography, a local tide gauge and wave climate data were collected. The result is a rich and unique observational dataset capturing berm erosion dynamics. This poster highlights the data collected and presents methods for processing and leveraging multi-sensor field observation data. The data obtained from this study will be used to support the development and validation of a numerical beach berm overtopping and overwash model that will allow for improved predictions of coastal flood damage during winter storms and large swells.

Schubert, J. E.; Gallien, T.; Shakeri Majd, M.; Sanders, B. F.

2012-12-01

50

Modular shield  

DOEpatents

A modular system for containing projectiles has a sheet of material including at least a polycarbonate layer held by a metal frame having a straight frame member corresponding to each straight edge of the sheet. Each frame member has a U-shaped shield channel covering and holding a straight edge of the sheet and an adjacent U-shaped clamp channel rigidly held against the shield channel. A flexible gasket separates each sheet edge from its respective shield channel; and each frame member is fastened to each adjacent frame member only by clamps extending between adjacent clamp channels.

Snyder, Keith W. (Sandia Park, NM)

2002-01-01

51

Effects of Building a Sand Barrier Berm to Mitigate the Effects of the Deepwater Horizon Oil Spill on Louisiana Marshes  

USGS Publications Warehouse

The State of Louisiana requested emergency authorization on May 11, 2010, to perform spill mitigation work on the Chandeleur Islands and on all the barrier islands from Grand Terre Island eastward to Sandy Point to enhance the capability of the islands to reduce the movement of oil from the Deepwater Horizon oil spill to the marshes. The proposed action-building a barrier berm (essentially an artificial island fronting the existing barriers and inlets) seaward of the existing barrier islands and inlets-'restores' the protective function of the islands but does not alter the islands themselves. Building a barrier berm to protect the mainland wetlands from oil is a new strategy and depends on the timeliness of construction to be successful. Prioritizing areas to be bermed, focusing on those areas that are most vulnerable and where construction can be completed most rapidly, may increase chances for success. For example, it may be easier and more efficient to berm the narrow inlets of the coastal section to the west of the Mississippi River Delta rather than the large expanses of open water to the east of the delta in the southern parts of the Breton National Wildlife Refuge (NWR). This document provides information about the potential available sand resources and effects of berm construction on the existing barrier islands. The proposed project originally involved removing sediment from a linear source approximately 1 mile (1.6 km) gulfward of the barrier islands and placing it just seaward of the islands in shallow water (~2-m depth where possible) to form a continuous berm rising approximately 6 feet (~2 m) above sea level (North American Vertical Datum of 1988-NAVD88) with an ~110-yd (~100-m) width at water level and a slope of 25:1 to the seafloor. Discussions within the U.S. Geological Survey (USGS) and with others led to the determination that point-source locations, such as Hewes Point, the St. Bernard Shoals, and Ship Shoal, were more suitable 'borrow' locations because sand content is insufficient along a linear track offshore from most of Louisiana's barrier islands. Further, mining sediment near the toe of the barrier island platform or edge of actively eroding barrier islands could create pits in the seafloor that will capture nearshore sand, thereby enhancing island erosion, and focus incoming waves (for example, through refraction processes) that could yield hotspots of erosion. In the Breton NWR, the proposed berm would be continuous from just south of Hewes Point to Breton Island for approximately 100 km with the exception of several passages for vessel access. Proposed volume estimates by sources outside of the USGS suggest that the structure in the Breton NWR would contain approximately 56 million cubic yards (42.8 m3) of sandy material. In the west, the berm would require approximately 36 million cubic yards (27.5 m3) of sandy material because this area has less open water than the area to the east of the delta. The planned berm is intended to protect the islands and inland areas from oil and would be sacrificial; that is, it will rapidly erode through natural processes. It is not part of the coastal restoration plan long discussed in Louisiana to rebuild barrier islands for hurricane protection of mainland infrastructure and habitat.

Lavoie, Dawn; Flocks, James G.; Kindinger, Jack L.; Sallenger, A.H., Jr.; Twichell, David C.

2010-01-01

52

Earth  

NSDL National Science Digital Library

With three levels to choose from on each page - beginner, intermediate or advanced - this site provides information on our plant Earth. There is a section about water on earth and its many different varities, like freshwater, groundwater, and frozen water. There is information about the chemical make-up of water and many images showing the different water anvironments. There is a section about life in water, such as animals, plants, and plankton.

2008-10-03

53

Earth  

NSDL National Science Digital Library

This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Earth. These data include planet size, orbit facts, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, surface materials and albedo. Images with descriptions show Earth features such as the Ross Ice Shelf in Antarctica, Simpson Desert in Australia, Mt. Etna in Sicily, the Cassiar Mountains in Canada, the Strait of Gibraltar, Mississippi River, Grand Canyon, Wadi Kufra Oasis in Libya, and Moon images such as Hadley Rille, Plum Crater, massifs and Moon rocks. These images were taken with the Galileo Spacecraft and by the Apollo missions.

54

Ray Shielding  

NSDL National Science Digital Library

In this activity, students will gather data on space radiation shielding by observing a flashlight beam as it shines through different material, and by measuring, predicting, counting, and weighing the proposed materials. They will then analyze their data, select the most protective and lightweight material for radiation shielding in a spacecraft, and develop a conclusion based on their results. The activity is designed to accompany the Kids' Science News Network (KSNN) 21st Century Exlporer 30-second news break entitled 'What Would You Hear in a Weather Report From Mars?' The activity includes a teacher's guide and instructions for students, and a Spanish translation is available.

55

Solar shield  

SciTech Connect

A flexible shield material having the characteristic of not transmitting solar heat, is supported on a frame which extends from end to end of an automobile or the like vehicle and is adjustable in length, having means on the opposite ends to be hooked to the front and rear bumpers and adapted to be locked, the longitudinal frame members including telescopic members so that the entire frame can be collapsed to a size adapted to be stored in the trunk of the average vehicle, and when extended space the sun shield from the vehicle body.

Johnson, B.L.

1980-01-22

56

Thermocouple shield  

DOEpatents

A thermocouple shield for use in radio frequency fields. In some embodiments the shield includes an electrically conductive tube that houses a standard thermocouple having a thermocouple junction. The electrically conductive tube protects the thermocouple from damage by an RF (including microwave) field and mitigates erroneous temperature readings due to the microwave or RF field. The thermocouple may be surrounded by a ceramic sheath to further protect the thermocouple. The ceramic sheath is generally formed from a material that is transparent to the wavelength of the microwave or RF energy. The microwave transparency property precludes heating of the ceramic sheath due to microwave coupling, which could affect the accuracy of temperature measurements. The ceramic sheath material is typically an electrically insulating material. The electrically insulative properties of the ceramic sheath help avert electrical arcing, which could damage the thermocouple junction. The electrically conductive tube is generally disposed around the thermocouple junction and disposed around at least a portion of the ceramic sheath. The concepts of the thermocouple shield may be incorporated into an integrated shielded thermocouple assembly.

Ripley, Edward B. (Knoxville, TN)

2009-11-24

57

Sound shield  

NASA Technical Reports Server (NTRS)

An improved test section for a supersonic or hypersonic wind tunnel is disclosed wherein the model tested is shielded from the noise normally radiated by the turbulent tunnel wall boundary layer. A vacuum plenum surrounds spaced rod elements making up the test chamber to extract some of the boundary layer as formed along the rod elements during a test to thereby delay the tendency of the rod boundary layers to become turbulent. Novel rod construction involves bending each rod slightly prior to machining the bent area to provide a flat segment on each rod for connection with the flat entrance fairing. Rods and fairing are secured to provide a test chamber incline on the order of 1 deg outward from the noise shield centerline to produce up to 65% reduction of the root mean square (rms) pressure over previously employed wind tunnel test sections at equivalent Reynolds numbers.

Creel, T. R., Jr.; Beckwith, I. E. (inventors)

1982-01-01

58

Skylab Solar Shield  

NASA Technical Reports Server (NTRS)

A sail like sunshade for possible use as a sunscreen for the Skylab Orbital Workshop (OWS) is shown being fabricated in the GE Building across the street from Johnson Space Center, Houston Texas. Three people help the steamstress feed the material through the sewing machine. The three-layered sunshade will be composed of a top layer of aluminized mylar, a middle layer of laminated nylon ripstop, and a bottom layer of thin nylon. Working on the sunshade are from left to right: Dale Gentry, Elizabeth Gauldin, Alyene Baker, and James H. Barnett Jr. Mrs. Baker, a GE employee, operates the double needle Singer sewing machine. Barnett is head of the Crew Equipment Development Section of JSC Crew Systems Division. Mrs. Gauldin is also with the Crew Systems Division. Gentry works for GE. The work shown here is part of the crash program underway to prepare a sunshield for Skylab to replace the orginal shield which was lost when Skylab 1 was launched on May 14, 1973. The improvised solar shield selected to be used will be carried to Earth orbit by the Skylab 2 crewman who will then deploy the reflective parasol to shade part of the OWS from the hot rays of the sun. Loss of the orginal sun shield has caused an overheating problem. in the Orbital Work Shop.

1973-01-01

59

Change in the length of the northern section of the Chandeleur Islands oil berm, September 5, 2010, through September 3, 2012  

USGS Publications Warehouse

On April 20, 2010, an explosion on the Deepwater Horizon oil rig drilling at the Macondo Prospect site in the Gulf of Mexico resulted in a marine oil spill that continued to flow through July 15, 2010. One of the affected areas was the Breton National Wildlife Refuge, which consists of a chain of low-lying islands, including Breton Island and the Chandeleur Islands, and their surrounding waters. The island chain is located approximately 115–150 kilometers north-northwest of the spill site. A sand berm was constructed seaward of, and on, the island chain. Construction began at the northern end of the Chandeleur Islands in June 2010 and ended in April 2011. The berm consisted of three distinct sections based on where the berm was placed relative to the islands. The northern section of the berm was built in open water on a submerged portion of the Chandeleur Islands platform. The middle section was built approximately 70–90 meters seaward of the Chandeleur Islands. The southern section was built on the islands’ beaches. Repeated Landsat and SPOT satellite imagery and airborne lidar were used to observe the disintegration of the berm over time. The methods used to analyze the remotely sensed data and the resulting, derived data for the northern section are described in this report.

Plant, N.G.; Guy, K.K.

2013-01-01

60

Change in the length of the middle section of the Chandeleur Islands oil berm, November 17, 2010, through September 6, 2011  

USGS Publications Warehouse

On April 20, 2010, an explosion on the Deepwater Horizon oil rig drilling at the Macondo Prospect site in the Gulf of Mexico resulted in a marine oil spill that continued to flow through July 15, 2010. One of the affected areas was the Breton National Wildlife Refuge, which consists of a chain of low-lying islands, including Breton Island and the Chandeleur Islands, and their surrounding waters. The island chain is located approximately 115-150 kilometers north-northwest of the spill site. A sand berm was constructed seaward of, and on, the island chain. Construction began at the northern end of the Chandeleur Islands in June 2010 and ended in April 2011. The berm consisted of three distinct sections based on where the berm was placed relative to the islands. The northern section of the berm was built in open water on a submerged portion of the Chandeleur Islands platform. The middle section was built approximately 70-90 meters seaward of the Chandeleur Islands. The southern section was built on the islands' beaches. Repeated Landsat and SPOT satellite imagery and airborne lidar were used to observe the disintegration of the berm over time. The methods used to analyze the remotely sensed data and the resulting, derived data for the middle section are described in this report.

Plant, N.G.; Guy, K.K.

2013-01-01

61

Biological Diversity of the Guiana Shield: Georeferencing Plants of the Guiana Shield  

E-print Network

will be ready soon (ca. 1900 specimens). #12;Georeferencing Plants of the Guiana Shield Google Earth uses KML files to share the information. When a user downloads a KML file it appears on the Places panel

Mathis, Wayne N.

62

Corium shield  

DOEpatents

A shield for restricting molten corium from flowing into a water sump disposed in a floor of a containment vessel includes upper and lower walls which extend vertically upwardly and downwardly from the floor for laterally bounding the sump. The upper wall includes a plurality of laterally spaced apart flow channels extending horizontally therethrough, with each channel having a bottom disposed coextensively with the floor for channeling water therefrom into the sump. Each channel has a height and a length predeterminedly selected for allowing heat from the molten corium to dissipate through the upper and lower walls as it flows therethrough for solidifying the molten corium therein to prevent accumulation thereof in the sump.

McDonald, Douglas B. (Pleasanton, CA); Buchholz, Carol E. (San Jose, CA)

1994-01-01

63

Advanced Multifunctional MMOD Shield: Radiation Shielding Assessment  

NASA Technical Reports Server (NTRS)

Deep space missions must contend with a harsh radiation environment Impacts to crew and electronics. Need to invest in multifunctionality for spacecraft optimization. MMOD shield. Goals: Increase radiation mitigation potential. Retain overall MMOD shielding performance.

Rojdev, Kristina; Christiansen, Eric

2013-01-01

64

Magnetic shielding  

DOEpatents

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.

Kerns, J.A.; Stone, R.R.; Fabyan, J.

1985-02-12

65

Thematic mapper research in the Earth sciences: Tectonic evaluation of the Nubian Shield of northeastern Sudan/southeastern Egypt using thematic mapper imagery  

NASA Technical Reports Server (NTRS)

The tectonic evaluation of the Nubian Shield using the Thematic Mapper (TM) imagery is progressing well and shows great promise. The TM tapes for the six LANDSAT 5 scenes covering the northern portion of the Red Sea hills were received, and preliminary maps and interpretations were made for most of the area. It is apparent that faulting and shearing associated with the major suture zones such as the Sol Hamed are clearly visible and that considerable detail can be seen. An entire quadrant of scene 173,45 was examined in detail using all seven bands, and every band combination was evaluated to best display the geology. A comparison was done with color ratio combinations and color combinations of the eigen vector bands to verify if band combinations of 7-red, 4-green, and 2-blue were indeed superior. There is no single optimum enhancement which provides the greatest detail for every image and no single combination of spectral bands for all cases, although bands 7, 4, and 2 do provide the best overall display. The color combination of the eigen vector bands proved useful in distinguishing fine detailed features.

1986-01-01

66

Space reactor shielding fabrication  

NASA Technical Reports Server (NTRS)

The fabrication of space reactor neutron shielding by a melting and casting process utilizing lithium hydride is described. The first neutron shield fabricated is a large pancake shape 86 inches in diameter, containing about 1700 pounds of lithium hydride. This shield, fabricated by the unique melting and casting process, is the largest lithium hydride shield ever built.

Welch, F. H.

1972-01-01

67

Using uplifted Holocene beach berms for paleoseismic analysis on the Santa María Island, south-central Chile  

NASA Astrophysics Data System (ADS)

Major earthquakes (M > 8) have repeatedly ruptured the Nazca-South America plate interface of south-central Chile involving meter scale land-level changes. Earthquake recurrence intervals, however, extending beyond limited historical records are virtually unknown, but would provide crucial data on the tectonic behavior of forearcs. We analyzed the spatiotemporal pattern of Holocene earthquakes on Santa María Island (SMI; 37°S), located 20 km off the Chilean coast and approximately 70 km east of the trench. SMI hosts a minimum of 21 uplifted beach berms, of which a subset were dated to calculate a mean uplift rate of 2.3 +/- 0.2 m/ky and a tilting rate of 0.022 +/- 0.002 °/ky. The inferred recurrence interval of strandline-forming earthquakes is ~180 years. Combining coseismic uplift and aseismic subsidence during an earthquake cycle, the net gain in strandline elevation in this environment is ~0.4 m per event.

Bookhagen, B.; Echtler, H. P.; Melnick, D.; Strecker, M. R.; Spencer, J. Q. G.

2006-08-01

68

Principles of quasistatic magnetic shielding with cylindrical and spherical shields  

Microsoft Academic Search

The basic principles that underlie materials-based quasistatic magnetic shielding are described. Shielding mechanisms are identified and shown in specific examples that involve long cylindrical and spherical shield geometries. Analytic results are given both for shields that enclose the shielded region and for shields that enclose the source. The two configurations are reciprocal in the sense that identical shields have identical

J. F. Hoburg; J. F. Hobug

1995-01-01

69

Predictions for Radiation Shielding Materials  

NASA Technical Reports Server (NTRS)

Radiation from galactic cosmic rays (GCR) and solar particle events (SPE) is a serious hazard to humans and electronic instruments during space travel, particularly on prolonged missions outside the Earth s magnetic fields. Galactic cosmic radiation (GCR) is composed of approx. 98% nucleons and approx. 2% electrons and positrons. Although cosmic ray heavy ions are 1-2% of the fluence, these energetic heavy nuclei (HZE) contribute 50% of the long-term dose. These unusually high specific ionizations pose a significant health hazard acting as carcinogens and also causing microelectronics damage inside spacecraft and high-flying aircraft. These HZE ions are of concern for radiation protection and radiation shielding technology, because gross rearrangements and mutations and deletions in DNA are expected. Calculations have shown that HZE particles have a strong preference for interaction with light nuclei. The best shield for this radiation would be liquid hydrogen, which is totally impractical. For this reason, hydrogen-containing polymers make the most effective practical shields. Shielding is required during missions in Earth orbit and possibly for frequent flying at high altitude because of the broad GCR spectrum and during a passage into deep space and LunarMars habitation because of the protracted exposure encountered on a long space mission. An additional hazard comes from solar particle events (SPEs) which are mostly energetic protons that can produce heavy ion secondaries as well as neutrons in materials. These events occur at unpredictable times and can deliver a potentially lethal dose within several hours to an unshielded human. Radiation protection for humans requires safety in short-term missions and maintaining career exposure limits within acceptable levels on future long-term exploration missions. The selection of shield materials can alter the protection of humans by an order of magnitude. If improperly selected, shielding materials can actually increase radiation damage due to penetration properties and nuclear fragmentation. Protecting space-borne microelectronics from single event upsets (SEUs) by transmitted radiation will benefit system reliability and system design cost by using optimal shield materials. Long-term missions on the surface of the Moon or Mars will require the construction of habitats to protect humans during their stay. One approach to the construction is to make structural materials from lunar or Martian regolith using a polymeric material as a binder. The hydrogen-containing polymers are considerably more effective for radiation protection than the regolith, but the combination minimizes the amount of polymer to be transported. We have made composites of simulated lunar regolith with two different polymers, LaRC-SI, a high-performance polyimide thermoset, and polyethylene, a thermoplastic.

Kiefer, Richard L.

2002-01-01

70

Meteoroid/Debris Shielding  

NASA Technical Reports Server (NTRS)

This report provides innovative, low-weight shielding solutions for spacecraft and the ballistic limit equations that define the shield's performance in the meteoroid/debris environment. Analyses and hypervelocity impact testing results are described that have been used in developing the shields and equations. Spacecraft shielding design and operational practices described in this report are used to provide effective spacecraft protection from meteoroid and debris impacts. Specific shield applications for the International Space Station (ISS), Space Shuttle Orbiter and the CONTOUR (Comet Nucleus Tour) space probe are provided. Whipple, Multi-Shock and Stuffed Whipple shield applications are described.

Christiansen, Eric L.

2003-01-01

71

Retro rocket plume actuated heat shield exhaust ports  

Microsoft Academic Search

A preliminary scheme was developed for base-mounted solid-propellant retro rocket motors to self-penetrate the Orion Crew Module heat shield for configurations with the heat shield retained during landings on Earth. In this system the motors propel impactors into structural push plates, which in turn push through the heat shield ablator material. The push plates are sized such that the port

Colleen Marrese-Reading; J. St. Vaughn; R. Frisbee; P. Zell; K. Hamm; J. Corliss; S. Gayle; R. Pain; D. Rooney; A. Ramos; D. Lewis; J. Shepherd; K. Inaba

2009-01-01

72

MINIMUM WEIGHT SHIELD SYNTHESIS  

Microsoft Academic Search

A simple model for radiation production and attenuation in a spherical ; multilayer reactor-shield assembly is introduced. Variational methods are ; applied to this model to minimize the weight subject to given specifications on ; the dose at the outside of the shield and on the properties of shielding ; materials. The method provides guidance in the choice of the

Troubetzkoy

1962-01-01

73

Enhanced Whipple Shield  

NASA Technical Reports Server (NTRS)

A hypervelocity impact (HVI) Whipple Shield and a method for shielding a wall from penetration by high velocity particle impacts where the Whipple Shield is comprised of spaced apart inner and outer metal sheets or walls with an intermediate cloth barrier arrangement comprised of ceramic cloth and high strength cloth which are interrelated by ballistic formulae.

Crews, Jeanne L. (Inventor); Christiansen, Eric L. (Inventor); Williamsen, Joel E. (Inventor); Robinson, Jennifer R. (Inventor); Nolen, Angela M. (Inventor)

1997-01-01

74

Collagen Corneal Shields  

Microsoft Academic Search

Collagen corneal shields were developed as a corneal bandage lens and are currently indicated for ocular surface protection following surgery and in traumatic and nontraumatic corneal conditions. Collagen shields are manufactured from porcine or bovine collagen and three different collagen shields are currently available with dissolution times of 12, 24, and 72 hours. The theoretical, experimental, and clinical evidence supports

C. E Willoughby; M Batterbury; S. B Kaye

2002-01-01

75

Rotating shielded crane system  

DOEpatents

A rotating, radiation shielded crane system for use in a high radiation test cell, comprises a radiation shielding wall, a cylindrical ceiling made of radiation shielding material and a rotatable crane disposed above the ceiling. The ceiling rests on an annular ledge intergrally attached to the inner surface of the shielding wall. Removable plugs in the ceiling provide access for the crane from the top of the ceiling into the test cell. A seal is provided at the interface between the inner surface of the shielding wall and the ceiling.

Commander, John C. (Idaho Falls, ID)

1988-01-01

76

Composite materials microstructure for radiation shielding  

NASA Technical Reports Server (NTRS)

Shielding against radiation is a concern for applications on earth, in space, and on extraterrestrial surfaces. On earth EMI is an important factor, while in space and on extraterrestrial surfaces particle (high charge-Z and high energy-E) radiation is a critical issue. Conventional metallic materials currently used for EMI shielding incur large weight penalties. To overcome this weight penalty, ultra-lightweight composite materials utilizing fillers ranging from carbon microballoons to silver coated ceramic microballoons are proposed. The crucial shielding requirement is conductivity of the constituent materials, while the hollow microballoon geometry is utilized to yield low weight. Methods of processing and composition effects are examined and these results are compared to the effectiveness of varying the conductive microballoon material. The resulting ultralightweight materials, developed for EMI shielding, can be tailored through the application of the understanding of the relative effects of variables such as those tested. Initial experimental results reveal that these tailored ultralightweight composite materials are superior to traditional aluminum shielding at only a small fraction of the weight.

Radford, Donald W.; Sadeh, Willy Z.; Cheng, Boyle C.

1992-01-01

77

Gravity Scaling of a Power Reactor Water Shield  

NASA Technical Reports Server (NTRS)

Water based reactor shielding is being considered as an affordable option for use on initial lunar surface power systems. Heat dissipation in the shield from nuclear sources must be rejected by an auxiliary thermal hydraulic cooling system. The mechanism for transferring heat through the shield is natural convection between the core surface and an array of thermosyphon radiator elements. Natural convection in a 100 kWt lunar surface reactor shield design has been previously evaluated at lower power levels (Pearson, 2007). The current baseline assumes that 5.5 kW are dissipated in the water shield, the preponderance on the core surface, but with some volumetric heating in the naturally circulating water as well. This power is rejected by a radiator located above the shield with a surface temperature of 370 K. A similarity analysis on a water-based reactor shield is presented examining the effect of gravity on free convection between a radiation shield inner vessel and a radiation shield outer vessel boundaries. Two approaches established similarity: 1) direct scaling of Rayleigh number equates gravity-surface heat flux products, 2) temperature difference between the wall and thermal boundary layer held constant on Earth and the Moon. Nussult number for natural convection (laminar and turbulent) is assumed of form Nu = CRa(sup n). These combined results estimate similarity conditions under Earth and Lunar gravities. The influence of reduced gravity on the performance of thermosyphon heat pipes is also examined.

Reid, Robert S.; Pearson, J. Boise

2008-01-01

78

Gravity Scaling of a Power Reactor Water Shield  

SciTech Connect

Water based reactor shielding is being considered as an affordable option for potential use on initial lunar surface reactor power systems. Heat dissipation in the shield from nuclear sources must be rejected by an auxillary thermal hydraulic cooling system. The mechanism for transferring heat through the shield is natural convection between the core surface and an array of thermosyphon radiator elements. Natural convection in a 100 kWt lunar surface reactor shield design has been previously evaluated at lower power levels (Pearson, 2006). The current baseline assumes that 5.5 kW are dissipated in the water shield, the preponderance on the core surface, but with some volumetric heating in the naturally circulating water as well. This power is rejected by a radiator located above the shield with a surface temperature of 370 K. A similarity analysis on a water-based reactor shield is presented examining the effect of gravity on free convection between a radiation shield inner vessel and a radiation shield outer vessel boundaries. Two approaches established similarity: 1) direct scaling of Rayleigh number equates gravity-surface heat flux products, 2) temperature difference between the wall and thermal boundary layer held constant on Earth and the Moon. Nussult number for natural convection (laminar and turbulent) is assumed of form Nu = CRa{sup n}. These combined results estimate similarity conditions under Earth and Lunar gravities. The influence of reduced gravity on the performance of thermosyphon heat pipes is also examined.

Reid, Robert S.; Pearson, J. Boise [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)

2008-01-21

79

The least expensive form of radiation shielding is a planetary atmosphere, but just how efficient is it? The walls of the International Space Station and the Space Shuttle provide substantial astronaut  

E-print Network

The least expensive form of radiation shielding is a planetary atmosphere, but just how efficient? In the previous problem 'Atmospheric Shielding from Radiation II' we estimated the atmospheric shielding of Earth (Earth) = 6,378 kilometers, R (Mars = 3,374 km) 24Atmospheric Shielding from Radiation III Problem 2: A

80

Technique for high axial shielding factor performance of large-scale, thin, open-ended, cylindrical Metglas magnetic shields  

NASA Astrophysics Data System (ADS)

Metglas 2705M is a low-cost commercially available, high-permeability cobalt-based magnetic alloy, provided as a 5.08-cm wide and 20.3-?m thick ribbon foil. We present an optimized construction technique for single-shell, large-scale (human-size), thin, open-ended cylindrical Metglas magnetic shields. The measured dc axial and transverse magnetic shielding factors of our 0.61-m diameter and 1.83-m long shields in the Earth's magnetic field were 267 and 1500, for material thicknesses of only 122 ?m (i.e., 6 foil layers). The axial shielding performance of our single-shell Metglas magnetic shields, obtained without the use of magnetic shaking techniques, is comparable to the performance of significantly thicker, multiple-shell, open-ended Metglas magnetic shields in comparable-magnitude, low-frequency applied external fields reported previously in the literature.

Malkowski, S.; Adhikari, R.; Hona, B.; Mattie, C.; Woods, D.; Yan, H.; Plaster, B.

2011-07-01

81

Technique for high axial shielding factor performance of large-scale, thin, open-ended, cylindrical Metglas magnetic shields.  

PubMed

Metglas 2705M is a low-cost commercially available, high-permeability cobalt-based magnetic alloy, provided as a 5.08-cm wide and 20.3-?m thick ribbon foil. We present an optimized construction technique for single-shell, large-scale (human-size), thin, open-ended cylindrical Metglas magnetic shields. The measured dc axial and transverse magnetic shielding factors of our 0.61-m diameter and 1.83-m long shields in the Earth's magnetic field were 267 and 1500, for material thicknesses of only 122 ?m (i.e., 6 foil layers). The axial shielding performance of our single-shell Metglas magnetic shields, obtained without the use of magnetic shaking techniques, is comparable to the performance of significantly thicker, multiple-shell, open-ended Metglas magnetic shields in comparable-magnitude, low-frequency applied external fields reported previously in the literature. PMID:21806224

Malkowski, S; Adhikari, R; Hona, B; Mattie, C; Woods, D; Yan, H; Plaster, B

2011-07-01

82

RF shielded connectors  

NASA Technical Reports Server (NTRS)

Gap, where cable joins connector housing, is shielded effectively by composite RF shielding made from suitable potting resin material (fumed silica, thixotropic prepolymer composition), conductive coating (silver-filled, flexible, polyurethane resin), and protective jacket (wax coated housing formed around another wax form having contours shaped to match configuration).

Fisher, A.; Clatterbuck, C.

1974-01-01

83

Shielding for thermal neutrons.  

PubMed

The problem of calculating the neutron capture gamma-ray dose rate due to thermal neutron capture in a boron or cadmium rectangular shield is considered. An example is given for shielding for a door at the exit of medical accelerator room maze in order to determine the optimum location of lead relative to the borated polyethylene. PMID:9029548

McCall, R C

1997-01-01

84

REACTOR SHIELD PENETRATION CALCULATIONS  

Microsoft Academic Search

Application of point-to-point attenuation functions to the calculation ; of fast neutron and gamma ray dose and energy absorption rates in and around ; reactor shields is described. A description of IBM-704 programs capable of ; evaluating attenuation functions along source-receiver paths in complex shields ; and performing a final integration over a source region is presented. (auth);

W. E. Edwards; J. E. MacDonald

1958-01-01

85

Whipple shield sizing equations  

NASA Technical Reports Server (NTRS)

Wipple shield sizing equations are given for use in current Space Station Freedom (SSF) Work Package 2 (WP-2) trade study activities. These equations are modifications of the 1969 Cour-Palais predictor equations which were used by McDonnell Douglas to size WP-2 meteoroid and debris shielding for the SSF preliminary design review. Recent hypervelocity impact (HVI) test results have shown that the original 1969 Cour-Palais predictor improperly scales to the particle sizes that the WP-2 shields must be designed to protect against. The original equations have been redesigned to correct this scaling deficiency. Substantial increases to WP-2 shielding weight estimates are indicated by the modified equations. Several possibilities exist, however, to reduce the weight of WP-2 shielding. These equations will be updated in the future as warranted by the results of ultra-high speed (greater than 19 km/sec) HVI tests and further analysis.

Christiansen, Eric L.

1991-01-01

86

Shielding Structures for Interplanetary Human Mission  

NASA Astrophysics Data System (ADS)

Since the end of Apollo missions, human spaceflight has been limited to the Low Earth Orbit (LEO), inside the protective magnetic field of the Earth, because astronauts are, to the largest degree, protected from the harsh radiation environment of the interplanetary space. However, this situation will change when space exploration missions beyond LEO will become the real challenge of the human exploration program. The feasibility of these missions in the solar system is thus strongly connected to the capability to mitigate the radiation-induced biological effects on the crew during the journey and the permanence on the intended planet surface. Inside the International Space Station (ISS), the volumes in which the crew spends most of the time, namely the crew quarters are the only parts that implement dedicated additional radiation shielding made of polyethylene tiles designed for mitigating SPE effects. Furthermore, specific radiation shielding materials are often added to the described configuration to shield crew quarters or the entire habitat example of these materials are polyethylene, liquid hydrogen, etc. but, increasing the size of the exploration vehicles to bring humans beyond LEO, and without the magnetosphere protection, such approach is unsustainable because the mass involved is a huge limiting factor with the actual launcher engine technology. Moreover, shielding against GCR with materials that have a low probability of nuclear interactions and in parallel a high ionizing energy loss is not always the best solution. In particular there is the risk to increase the LET of ions arriving at the spacecraft shell, increasing their Radio-Biological Effectiveness. Besides, the production of secondary nuclei by projectile and target fragmentation is an important issue when performing an engineering assessment of materials to be used for radiation shielding. The goal of this work is to analyze different shielding solutions to increase as much as possible the radiation shielding power of the interplanetary habitat structures, like the spacecraft shell, minimizing the amount of mass used. From the radiation protection point of view the spacecraft shell is an interesting spacecraft system because it surrounds almost homogeneously all the habitat and it is typically composed by the Micrometeorites and Debris Protection Systems (MDPS), the Multilayer Insulation (MLI) for thermal control purposes, and the primary structure that offers the pressure containment functionality. Nevertheless, the spacecraft internal outfitting is important to evaluate the different shielded areas in the habitat. Using Geant4 Monte Carlo simulations toolkit through GRAS (Geant4 Radiation Analysis for Space) tool, different spacecraft structures will be analyzed for their shielding behavior in terms of fluxes, dose reduction and radiation quality, and for their implementation in a real pressurized module. Effects on astronauts and electronic equipments will be also assessed with respect to the standard aluminum structures.

Tracino, Emanuele; Lobascio, Cesare

2012-07-01

87

Radiation Shielding Materials  

NASA Technical Reports Server (NTRS)

NASA has relied on the materials to provide radiation shielding for astronauts since the first manned flights. Until very recently existing materials in the structure of manned spacecraft as well as the equipment and consumables onboard have been taken advantage of for radiation shielding. With the advent of the International Space Station and the prospect of extended missions to the Moon or Mars, it has been found that the materials, which were included in the spacecraft for other reasons, do not provide adequate shielding. For the first time materials are being added to manned missions solely to improve the radiation shielding. It is now recognized that dual use materials must be identified/developed. These materials must serve a purpose as part of the spacecraft or its cargo and at the same time be good shielding. This paper will review methods for evaluating the radiation shielding effectiveness of materials and describe the character of materials that have high radiation shielding effectiveness. Some candidate materials will also be discussed.

Adams, James H., Jr.; Rose, M. Franklin (Technical Monitor)

2001-01-01

88

iSHIELD - A Line Source Application of SHIELD11  

SciTech Connect

iSHIELD11 performs a line-source numerical integration of radiation source terms that are defined by the iSHIELD11 computer code[1] . An example is provided to demonstrate how one can use iSHIELD11 to perform a shielding analysis for a 250 GeV electron linear accelerator.

Nelson, W.R.; Rokni, S.H.; /SLAC

2006-04-27

89

Gravity Scaling of a Power Reactor Water Shield  

NASA Technical Reports Server (NTRS)

A similarity analysis on a water-based reactor shield examined the effect of gravity on free convection between a reactor shield inner and outer vessel boundaries. Two approaches established similarity between operation on the Earth and the Moon: 1) direct scaling of Rayleigh number equating gravity-surface heat flux products, 2) temperature difference between the wall and thermal boundary layer held constant. Nusselt number for natural convection (laminar and turbulent) is assumed of form Nu = CRa(sup n).

Reid, Robert S.; Pearson, J. Boise

2007-01-01

90

Alternate shield material feasibility  

SciTech Connect

The feasibility and cost/benefit of using materials other than stainless steel for in-vessel neutron shielding in large LMFBRs were investigated. Canned vibratorally compacted B/sub 4/C powder shields were found to be much more economical than stainless steel (a savings of $1.1M in loop plant designs and $9.4M in pool plant designs). The helium gas pressure buildup in B/sub 4/C shields placed around LMFBR in-vessel components (direct reactor heat exchangers in a loop reactor and intermediate heat exchangers in a pool reactor) would only be 0.04 atm after 40 y of reactor operation (with 80% dense powder). The irradiation-induced swelling of the B/sub 4/C would only be 0.002%. No adverse reactor impact would occur if the B/sub 4/C escaped from the B/sub 4/C shields.

Specht, E.R.; Levitt, L.B.

1984-04-01

91

Electrodynamic Dust Shield Demonstrator  

NASA Technical Reports Server (NTRS)

The objective of the project was to design and manufacture a device to demonstrate a new technology developed by NASA's Electrostatics and Surface Physics Laboratory. The technology itself is a system which uses magnetic principles to remove regolith dust from its surface. This project was to create an enclosure that will be used to demonstrate the effectiveness of the invention to The Office of the Chief Technologist. ONE of the most important challenges of space exploration is actually caused by something very small and seemingly insignificant. Dust in space, most notably on the moon and Mars, has caused many unforeseen issues. Dirt and dust on Earth, while a nuisance, can be easily cleaned and kept at bay. However, there is considerably less weathering and erosion in space. As a result, the microscopic particles are extremely rough and abrasive. They are also electrostatically charged, so they cling to everything they make contact with. This was first noted to be a major problem during the Apollo missions. Dust would stick to the spacesuits, and could not be wiped off as predicted. Dust was brought back into the spacecraft, and was even inhaled by astronauts. This is a major health hazard. Atmospheric storms and other events can also cause dust to coat surfaces of spacecraft. This can cause abrasive damage to the craft. The coating can also reduce the effectiveness of thermal insulation and solar panels.' A group of engineers at Kennedy Space Center's Electrostatics and Surface Physics Laboratory have developed a new technology, called the Electrodynamic Dust Shield, to help alleviate these problems. It is based off of the electric curtain concept developed at NASA in 1967. "The EDS is an active dust mitigation technology that uses traveling electric fields to transport electrostatically charged dust particles along surfaces. To generate the traveling electric fields, the EDS consists of a multilayer dielectric coating with an embedded thin electrode grid running a multiphase low frequency AC signal. Electrostatically charged particles, such as those encountered on the moon, Mars, or an asteroid, are carried along by the traveling field due to the action of Coulomb and dielectrophoretic forces."2 The technical details have been described in a separate article. This document details the design and construction process of a small demonstration unit. Once finished, this device will go to the Office of the ChiefTechnologist at NASA headquarters, where it will be used to familiarize the public with the technology. 1 NASA KSC FO Intern, Prototype Development Laboratory, Kennedy Space Center, University of Central Florida Kennedy Space

Stankie, Charles G.

2013-01-01

92

Side Shield for Wall Support  

NASA Technical Reports Server (NTRS)

Method employs curved shield on each side of mining machine. In stowed position, shield folded against roof-support columns on one side. In deployed position, shield raised and braced against coal-seam wall by hydraulic cylinder. Shield supports wall until roof and wall properly secured by bolting and cement coating.

Lewis, E. V.

1985-01-01

93

Sea-level proxies extracted from GPR reflection data collected across recently formed berm, beach ridge and swale deposits on the island of Anholt, Denmark  

NASA Astrophysics Data System (ADS)

GPR reflection data have been collected across the most recent part of a berm, beach ridge and swale system formed during the last 130 years on the northern coast of the island of Anholt, the Kattegat, Denmark. The reflected arrivals have a peak frequency of about 250 MHz and they image the subsurface with a vertical resolution of 0.1-0.2 m to a maximum depth of 5 m below the surface. The berm and beach ridges with maximum heights of about 1.8 m and 1.5 m, respectively, appear as mounded features in the GPR sections. The berm ridge also contains low-angle, seaward dipping reflections. Similar sea-ward dipping reflections are also observed below swales, and current swale surfaces appear to constitute erosion surfaces. Reflections downlapping on a package of reflections, which is interpreted to be representative of upper shoreface deposits, are suggested to constitute good proxies of sea level. Tamura et al. (2008) suggested that similar downlapping reflections may represent a depth level of about 1 m below the mean sea level based on investigations of the Kujukuri strand plain in eastern Japan. We have made 17 depth readings of such downlaps along our 159-m-long profile. The average depth of these downlap points is 0.003 m below present mean sea level (pmsl). Individual readings fall in the range of -0.5 m to +0.5 above pmsl, consistent with the majority of current, annual sea-level variations as recorded by the Danish Maritime Safety Administration at a position about 50 km southwest of Anholt. The mean sea level has changed insignificantly in the study area during ridge formation, and we assume that these proxies may form a strong basis for constructing palaeo-sea level curves for fossil (ages of up to about 7500 years), raised beach-ridge systems along the shores of the Kattegat and the Baltic Sea. Reference T. Tamura, F. Murakami, F. Nanayama, K. Watanabe, Y. Saito, 2008. Ground-penetrating radar profiles of Holocene raised-beach deposits in the Kujukuri strand plain, Pacific coast of eastern Japan, Marine Geology, 248, 11-27.

Nielsen, L.; Clemmensen, L. B.

2009-04-01

94

Regolith-Derived Heat Shield for Planetary Body Entry and Descent System with In-Situ Fabrication  

NASA Technical Reports Server (NTRS)

High-mass planetary surface access is one of NASA's Grand Challenges involving entry, descent, and landing (EDL). Heat shields fabricated in-situ can provide a thermal protection system for spacecraft that routinely enter a planetary atmosphere. Fabricating the heat shield from extraterrestrial regolith will avoid the costs of launching the heat shield mass from Earth. This project investigated three methods to fabricate heat shield using extraterrestrial regolith and performed preliminary work on mission architectures.

Hogue, Michael D.; Mueller, Robert P.; Sibille, Laurent; Hintze, Paul E.; Rasky, Daniel J.

2012-01-01

95

Shield sizing and response equations  

NASA Technical Reports Server (NTRS)

A consolidated list is presented of meteoroid debris shield equations which have been given in the referenced memorandums. In some cases, equations have been updated; thus, this memorandum supersedes reference 1. The equations are presented in two parts: (1) shield sizing equations which are used to produce preliminary estimates of shielding weights; and (2) response equations to describe the impact conditions (projectile size as a function of velocity, density, and impact angle) causing failure of a given shield that are to be used for probability analyses (such as in the modified BUMPER program). Specific equations are given that are applicable for the following types of shields: aluminum Whipple shields; Nextel multishock (MS) shields; and mesh double bumper (MDB) shields. These equations will be updated in the future as warranted by the results of additional HVI tests, analyses, and shield modeling.

Christiansen, Eric L.

1991-01-01

96

Shielded planar write head  

NASA Astrophysics Data System (ADS)

Field calculation with a finite-element method was performed for optimization of the shielded planar head composed of a tapered pole in both down and cross track directions and a wrap-around shield. Especially, effect of the taper angle of the main pole and the gap length and the height of the shield on head field was investigated to obtain a strong head field with a sharp distribution. In order to explore potential of the planar head, comparison with a conventional head with a normal main pole with a short throat was made and feasibility of 1 Tbit/in 2 recording with patterned media was discussed in terms of magnetization reversals of aimed track and thermal stability of magnetization on adjacent tracks.

Yamakawa, K.; Ise, K.; Takahashi, S.; Honda, N.; Ouchi, K.

97

Radiation shielding composition  

DOEpatents

A composition for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm.sup.3 and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile.

Quapp, William J. (Idaho Falls, ID); Lessing, Paul A. (Idaho Falls, ID)

2000-12-26

98

Radiation shielding composition  

DOEpatents

A composition is disclosed for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm{sup 3} and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile. 5 figs.

Quapp, W.J.; Lessing, P.A.

1998-07-28

99

Radiation shielding composition  

DOEpatents

A composition for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm.sup.3 and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile.

Quapp, William J. (Idaho Falls, ID); Lessing, Paul A. (Idaho Falls, ID)

1998-01-01

100

Composition for radiation shielding  

DOEpatents

A composition for use as a radiation shield. The shield has a depleted urum core for absorbing gamma rays and a bismuth coating for preventing chemical corrosion and absorbing gamma rays. Alternatively, a sheet of gadolinium may be positioned between the uranium core and the bismuth coating for absorbing neutrons. The composition is preferably in the form of a container for storing materials that emit radiation such as gamma rays and neutrons. The container is preferably formed by casting bismuth around a pre-formed uranium container having a gadolinium sheeting, and allowing the bismuth to cool. The resulting container is a structurally sound, corrosion-resistant, radiation-absorbing container.

Kronberg, James W. (Aiken, SC)

1994-01-01

101

Glove box shield  

DOEpatents

According to the present invention, a shield for a glove box housing radioactive material is comprised of spaced apart clamping members which maintain three overlapping flaps in place therebetween. There is a central flap and two side flaps, the side flaps overlapping at the interior edges thereof and the central flap extending past the intersection of the side flaps in order to insure that the shield is always closed when the user withdraws his hand from the glove box. Lead loaded neoprene rubber is the preferred material for the three flaps, the extent of lead loading depending upon the radiation levels within the glove box.

Brackenbush, Larry W. (Richland, WA); Hoenes, Glenn R. (Richland, WA)

1981-01-01

102

SHIELDING COMPUTER PROGRAM 14-0, REACTOR SHIELD ANALYSIS  

Microsoft Academic Search

Shielding Computer Program 14-0 evaluates point-topoint attenuation ; functions and integrates over source regions to perform reactor-shield ; penetration calculations for neutrons and gamma rays. Neutron dose rates and ; gamma ray flux and dose and energy absorption rates can be computed for positions ; in and around complex reactor shields containing multiple sources described in a ; cylindrical coordinate

J. T. Martin; J. P. Yalch; W. E. Edwards

1958-01-01

103

Lightweight blast shield  

DOEpatents

A tandem warhead missile arrangement that has a composite material housing structure with a first warhead mounted at one end and a second warhead mounted near another end of the composite structure with a dome shaped composite material blast shield mounted between the warheads to protect the second warhead from the blast of the first warhead.

Mixon, Larry C. (Madison, AL); Snyder, George W. (Huntsville, AL); Hill, Scott D. (Toney, AL); Johnson, Gregory L. (Decatur, AL); Wlodarski, J. Frank (Huntsville, AL); von Spakovsky, Alexis P. (Huntsville, AL); Emerson, John D. (Arab, AL); Cole, James M. (Huntsville, AL); Tipton, John P. (Huntsville, AL)

1991-01-01

104

Multilayer radiation shield  

Microsoft Academic Search

A power generation system including: a generator including a rotor including a superconductive rotor coil coupled to a rotatable shaft; a first prime mover drivingly coupled to the rotatable shaft; and a thermal radiation shield, partially surrounding the rotor coil, including at least a first sheet and a second sheet spaced apart from the first sheet by centripetal force produced

John Arthur Urbahn; Evangelos Trifon Laskaris

2009-01-01

105

Project BioShield  

Microsoft Academic Search

Summary Many potential biological terrorism agents lack available countermeasures. President Bush proposed Project BioShield to encourage companies to develop new bioterror countermeasures. The main provisions of that proposal include: (1) relaxing procedures for bioterrorism-related procurement and peer review; (2) guaranteeing a market through contract authority granted to the Secretary of Health and Human Services (HHS) to buy countermeasures following Presidential

Frank Gottron

106

Shields for small molecules  

PubMed Central

Nucleic acid aptamers have been employed to shield small molecules so that one among many similar reactive functional groups can be modified. This provides access to new chemical entities with potentially interesting properties while avoiding the use of covalent protecting groups. PMID:23000986

Silverman, Scott K.

2012-01-01

107

Shield against radiations  

SciTech Connect

This patent describes a shield against ionizing radiations that comprises at least one layer of an aggregate-containing cement-based conglomerate or an aggregate-containing cement-based mortar wherein the aggregate consists essentially of floated galena or mixtures thereof which at least one boron mineral.

Grifoni, S.

1988-02-23

108

Materials for electromagnetic interference shielding  

Microsoft Academic Search

Materials for the electromagnetic interference (EMI) shielding of electronics and radiation sources are reviewed, with emphasis\\u000a on composite materials and resilient EMI gasket materials, which shield mainly by reflection of the radiation at a high frequency.

D. D. L. Chung

2000-01-01

109

Self-Cleaning Transparent Dust Shields for Protecting Solar Panels and Other Devices  

Microsoft Academic Search

The development of transparent flexible dust shields using both single- and three-phase electrodynamic shields is reported here for possible application on Mars and Earth to minimize obscuration of solar panels from the deposition of dust. The electrodynamic screens (EDS) are made of transparent plastic sheets, such as polyethylene terephthalate (PET) for its UV radiation resistance, and a set of parallel

M. K. Mazumder; R. Sharma; A. S. Biris; J. Zhang; C. Calle; M. Zahn

2007-01-01

110

Heat Shield Paves the Way for Commercial Space  

NASA Technical Reports Server (NTRS)

The Phenolic-Impregnated Carbon Ablator (PICA) heat shield, a lightweight material designed to withstand high temperatures, was used for the Stardust’s reentry into Earth’s atmosphere. Hawthorne, California-based SpaceX later worked with the inventors at Ames Research Center to outfit PICA on its Dragon capsule, which is now delivering cargo to and from the International Space Station through NASA’s Commercial Resupply Services contracts program.

2014-01-01

111

SSC environmental radiation shielding  

SciTech Connect

The environmental radiation shielding requirements of the SSC have been evaluated using currently available computational tools that incorporate the well known processes of energy loss and degradation of high energy particles into Monte Carlo computer codes. These tools permit determination of isodose contours in the matter surrounding a source point and therefore the specification of minimum thicknesses or extents of shielding in order to assure annual dose equivalents less than some specified design amount. For the general public the annual dose equivalent specified in the design is 10 millirem, small compared to the dose from naturally occurring radiation. The types of radiation fall into two classes for the purposes of shielding determinations-hadrons and muons. The sources of radiation at the SSC of concern for the surrounding environment are the interaction regions, the specially designed beam dumps into which the beams are dumped from time to time, and beam clean-up regions where stops remove the beam halo in order to reduce experimental backgrounds. A final, unlikely source of radiation considered is the accidental loss of the full beam at some point around the ring. Conservative choices of a luminosity of 10{sup 34} cm{sup {minus}2}s{sup {minus}1} and a beam current three times design have been made in calculating the required shielding and boundaries of the facility. In addition to determination of minimum distances for the annual dose equivalents, the question of possible radioactivity produced in nearby wells or in municipal water supplies is addressed. The designed shielding distances and beam dumps are such that the induced radioactivity in ground water is safely smaller than the levels permitted by EPA and international agencies.

Jackson, J.D. [ed.

1987-07-01

112

Flexible Multi-Shock Shield  

NASA Technical Reports Server (NTRS)

Flexible multi-shock shield system and method are disclosed for defending against hypervelocity particles. The flexible multi-shock shield system and method may include a number of flexible bumpers or shield layers spaced apart by one or more resilient support layers, all of which may be encapsulated in a protective cover. Fasteners associated with the protective cover allow the flexible multi-shock shield to be secured to the surface of a structure to be protected.

Christiansen, Eric L. (Inventor); Crews, Jeanne L. (Inventor)

2005-01-01

113

Thick Galactic Cosmic Radiation Shielding Using Atmospheric Data  

NASA Technical Reports Server (NTRS)

NASA is concerned with protecting astronauts from the effects of galactic cosmic radiation and has expended substantial effort in the development of computer models to predict the shielding obtained from various materials. However, these models were only developed for shields up to about 120 g!cm2 in thickness and have predicted that shields of this thickness are insufficient to provide adequate protection for extended deep space flights. Consequently, effort is underway to extend the range of these models to thicker shields and experimental data is required to help confirm the resulting code. In this paper empirically obtained effective dose measurements from aircraft flights in the atmosphere are used to obtain the radiation shielding function of the earth's atmosphere, a very thick shield. Obtaining this result required solving an inverse problem and the method for solving it is presented. The results are shown to be in agreement with current code in the ranges where they overlap. These results are then checked and used to predict the radiation dosage under thick shields such as planetary regolith and the atmosphere of Venus.

Youngquist, Robert C.; Nurge, Mark A.; Starr, Stanley O.; Koontz, Steven L.

2013-01-01

114

Improved ferrous shielding for flat cables  

NASA Technical Reports Server (NTRS)

To improve shielding of flat multicore cables, a thin, seamless ferrous shield around all cores optimizes low frequency magnetic shielding. Such shielding is covered with an ultrathin seamless coat of highly conductive nonferrous material.

Drechsler, R. J.

1969-01-01

115

Radiation-Shielding Polymer/Soil Composites  

NASA Technical Reports Server (NTRS)

It has been proposed to fabricate polymer/ soil composites primarily from extraterrestrial resources, using relatively low-energy processes, with the original intended application being that habitat structures constructed from such composites would have sufficient structural integrity and also provide adequate radiation shielding for humans and sensitive electronic equipment against the radiation environment on the Moon and Mars. The proposal is a response to the fact that it would be much less expensive to fabricate such structures in situ as opposed to transporting them from Earth.

Sen, Subhayu

2007-01-01

116

Grounding and shielding techniques  

SciTech Connect

Grounding and shielding of electrical components and subsystems have always been a source of nuisance problems. In systems where large amounts of energy are moved in short, high power pulses, these problems may no longer be of nuisance value, but may become critical to the survival and well being of sensitive subsystems and adjacent electronics which may be functionally unreleated to the pulse power system. As it happens, most of the problems associated with grounding and shielding turn out to be conceptually simple but, similar to computer systems, become lost in a maze of complexity and a jungle of confusion. It is the intention of this presentation to illuminate those practices which will lead to problems later and to remove some of the apparent mystery from the sources of electromagnetic interference (EMI). Also, a set of rules will be presented which hopefully will help to prevent or solve problems derived from EMI.

Burkes, T.R.

1980-01-01

117

Gas shielding apparatus  

DOEpatents

An apparatus is disclosed for preventing oxidation by uniformly distributing inert shielding gas over the weld area of workpieces such as pipes being welded together. The apparatus comprises a chamber and a gas introduction element. The chamber has an annular top wall, an annular bottom wall, an inner side wall and an outer side wall connecting the top and bottom walls. One side wall is a screen and the other has a portion defining an orifice. The gas introduction element has a portion which encloses the orifice and can be one or more pipes. The gas introduction element is in fluid communication with the chamber and introduces inert shielding gas into the chamber. The inert gas leaves the chamber through the screen side wall and is dispersed evenly over the weld area. 3 figs.

Brandt, D.

1985-12-31

118

Composition for radiation shielding  

DOEpatents

A composition for use as a radiation shield is disclosed. The shield has a depleted uranium core for absorbing gamma rays and a bismuth coating for preventing chemical corrosion and absorbing gamma rays. Alternatively, a sheet of gadolinium may be positioned between the uranium core and the bismuth coating for absorbing neutrons. The composition is preferably in the form of a container for storing materials that emit radiation such as gamma rays and neutrons. The container is preferably formed by casting bismuth around a pre-formed uranium container having a gadolinium sheeting, and allowing the bismuth to cool. The resulting container is a structurally sound, corrosion-resistant, radiation-absorbing container. 2 figs.

Kronberg, J.W.

1994-08-02

119

Gas shielding apparatus  

DOEpatents

An apparatus for preventing oxidation by uniformly distributing inert shielding gas over the weld area of workpieces such as pipes being welded together. The apparatus comprises a chamber and a gas introduction element. The chamber has an annular top wall, an annular bottom wall, an inner side wall and an outer side wall connecting the top and bottom walls. One side wall is a screen and the other has a portion defining an orifice. The gas introduction element has a portion which encloses the orifice and can be one or more pipes. The gas introduction element is in fluid communication with the chamber and introduces inert shielding gas into the chamber. The inert gas leaves the chamber through the screen side wall and is dispersed evenly over the weld area.

Brandt, Daniel (Los Alamos, NM)

1985-01-01

120

Gas shielding apparatus  

DOEpatents

An apparatus for preventing oxidation by uniformly distributing inert shielding gas over the weld area of workpieces such as pipes being welded together. The apparatus comprises a chamber and a gas introduction element. The chamber has an annular top wall, an annular bottom wall, an inner side wall and an outer side wall connecting the top and bottom walls. One side wall is a screen and the other has a portion defining an orifice. The gas introduction element has a portion which encloses the orifice and can be one or more pipes. The gas introduction element is in fluid communication with the chamber and introduces inert shielding gas into the chamber. The inert gas leaves the chamber through the screen side wall and is dispersed evenly over the weld area.

Brandt, D.

1984-06-05

121

NEUTRON SHIELDING STRUCTURE  

Microsoft Academic Search

A lightweight neutron shielding structure comprises a honeycomb core ; which is filled with a neutron absorbing powder. The honeycomb core is faced ; with parallel planar facing sheets to form a lightweight rigid unit. Suitable ; absorber powders are selected from among the following: B, BâC, BâO\\/; sub 3\\/, CaBâ, LiâCO3, LiOH, LiBOâ, Li\\/s ub 2\\/O. The facing ;

Mattingly

1962-01-01

122

Ablative shielding for hypervelocity projectiles  

NASA Technical Reports Server (NTRS)

A hypervelocity projectile shield which includes a hollow semi-flexible housing fabricated from a plastic like, or otherwise transparent membrane which is filled with a fluid (gas or liquid) is presented. The housing has a inlet valve, similar to that on a tire or basketball, to introduce an ablating fluid into the housing. The housing is attached by a Velcro mount or double-sided adhesive tape to the outside surface of a structure to be protected. The housings are arrayed in a side-by-side relationship for complete coverage of the surface to be protected. In use, when a hypervelocity projectile penetrates the outer wall of a housing it is broken up and then the projectile is ablated as it travels through the fluid, much like a meteorite 'burns up' as it enters the earth's atmosphere, and the housing is deflated. The deflated housing can be easily spotted for replacement, even from a distance. Replacement is then accomplished by simply pulling a deflated housing off the structure and installing a new housing.

Rucker, Michelle A. (inventor)

1993-01-01

123

Shield design, analysis, and testing to survive stainless steel projectiles  

SciTech Connect

During the 3-year period of 1987 through 1989, the Advanced Shield Phenomenology Program included a research and development effort, with both experimental work and analytical support, to design a low weight, survivable shield against a stainless steel projectile at low earth orbit velocity. The specific threat used was a 1.75 gram, length to diameter ratio of one, stainless steel cylinder. The impact velocity was {approximately}7 km/s. Testing was performed at the Arnold Engineering Development Center, Arnold Air Force Base, Tullahoma, Tennessee. Sixteen shield configurations were tested. The Hull hydrocode was used for detailed analysis of five impact configurations. A successful shield was designed, which had a stainless steel front and back plate and 15.24 cm of carbon felt disrupter. The success of this configuration against the stainless steel threat was repeated. In comparison with the solid homogeneous aluminum shield necessary to stop the same threat, the layered shield developed has an areal density (mass per unit area) of 15.7% of the solid aluminum shield. Six conclusions of particular interest from the stainless steel work are summarized briefly as follows: the yaw angle of a cylindrical projectile at impact has a significant effect on shield survivability; areal density alone may not be enough to adequately model front plate behavior; thickness and material should be considered as separate variables; stainless steel very possibly is more damaging than can be accounted for by its density alone; a double-layer front plate produced no significant change in survivability; analytical results and test results are overall in excellent agreement; and hydrocode analysis is a useful tool in design and development of hypervelocity shields. 10 refs., 31 figs., 9 tabs.

Brewer, E.D.; Hendrich, W.R.; Thomas, D.G.; Smith, J.E.

1990-01-01

124

Novel shielding materials for space and air travel.  

PubMed

The reduction of dose onboard spacecraft and aircraft by appropriate shielding measures plays an essential role in the future development of space exploration and air travel. The design of novel shielding strategies and materials may involve hydrogenous composites, as it is well known that liquid hydrogen is most effective in attenuating charged particle radiation. As precursor for a later flight experiment, the shielding properties of newly developed hydrogen-rich polymers and rare earth-doped high-density rubber were tested in various ground-based neutron and heavy ion fields and compared with aluminium and polyethylene as reference materials. Absorbed dose, average linear energy transfer and gamma-equivalent neutron absorbed dose were determined by means of LiF:Mg,Ti thermoluminescence dosemeters and CR-39 plastic nuclear track detectors. First results for samples of equal aerial density indicate that selected hydrogen-rich plastics and rare-earth-doped rubber may be more effective in attenuating cosmic rays by up to 10% compared with conventional aluminium shielding. The appropriate adaptation of shielding thicknesses may thus allow reducing the biologically relevant dose. Owing to the lower density of the plastic composites, mass savings shall result in a significant reduction of launch costs. The experiment was flown as part of the European Space Agency's Biopan-5 mission in May 2005. PMID:16717109

Vana, N; Hajek, M; Berger, T; Fugger, M; Hofmann, P

2006-01-01

125

Justification for Shielded Receiver Tube Additional Lead Shielding  

SciTech Connect

In order to reduce high radiation dose rates encountered when core sampling some radioactive waste tanks the addition of 240 lbs. of lead shielding is being considered to the shielded receiver tube on core sample trucks No.1, No.3 and No.4. The lead shielding is 4 inch diameter x 1/2 inch thick half rounds that have been installed around the SR tube over its' full length. Using three unreleased but independently reviewed structural analyses HNF-6018 justifies the addition of the lead shielding.

BOGER, R.M.

2000-04-11

126

Exploring the Feasibility of Electrostatic Shielding for Spacecrafts  

NASA Technical Reports Server (NTRS)

NASA is moving forward towards the agency's new vision for space exploration in the 21st Century encompassing a broad range of human and robotic missions including missions to Moon, Mars and beyond. Exposure from the hazards of severe space radiation in deep space long duration missions is the show stopper. Langley has developed state-of-the-art radiation protection and shielding technology for space missions. The payload penalty demands a very stringent requirement on the design of the spacecrafts for human deep space missions. The exploration beyond low Earth orbit (LEO) to enable routine access to more interesting regions of space will require protection from the hazards of the accumulated exposures of space radiation, Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE), and minimizing the production of secondary radiation is a great advantage. There is a need to look to new horizons for newer technologies. The present investigation explores the feasibility of using electrostatic shielding in concert with innovative materials shielding and protection technologies. The asymmetries of the radiation shielding problem would be exploited in the electrostatics shielding process. The goal is to repel enough positive charge ions so that they miss the spacecraft without attracting thermal electrons. Conclusions are drawn about the advantages the electrostatic shielding, should it be successful, would bring to the radiation protection design process.

Tripathi, R. K.; Wilson, J. W.; Youngquist, R. C.

2005-01-01

127

Spacecraft ceramic protective shield  

NASA Technical Reports Server (NTRS)

A low areal density protective shield apparatus, and method for making same, for protecting spacecraft structures from impact with hypervelocity objects, including a bumper member comprising a bumper ceramic layer, a bumper shock attenuator layer, and a bumper confining layer. The bumper ceramic layer can be SiC or B.sub.4 C; the bumper shock attenuator layer can be zirconia felt; and the bumper confining layer can be aluminum. A base armor member can be spaced from the bumper member and a ceramic fiber-based curtain can be positioned between the bumper and base armor members.

Larriva, Rene F. (Inventor); Nelson, Anne (M.); Czechanski, James G. (Inventor); Poff, Ray E. (Inventor)

1995-01-01

128

Accelerator-based validation of shielding codes  

SciTech Connect

The space radiation environment poses risks to astronaut health from a diverse set of sources, ranging from low-energy protons and electrons to highly-charged, high-energy atomic nuclei and their associated fragmentation products, including neutrons. The low-energy protons and electrons are the source of most of the radiation dose to Shuttle and ISS crews, while the more energetic particles that comprise the Galactic Cosmic Radiation (protons, He, and heavier nuclei up to Fe) will be the dominant source for crews on long-duration missions outside the earth's magnetic field. Because of this diversity of sources, a broad ground-based experimental effort is required to validate the transport and shielding calculations used to predict doses and dose-equivalents under various mission scenarios. The experimental program of the LBNL group, described here, focuses principally on measurements of charged particle and neutron production in high-energy heavy-ion fragmentation. Other aspects of the program include measurements of the shielding provided by candidate spacesuit materials against low-energy protons (particularly relevant to extra-vehicular activities in low-earth orbit), and the depth-dose relations in tissue for higher-energy protons. The heavy-ion experiments are performed at the Brookhaven National Laboratory's Alternating Gradient Synchrotron and the Heavy-Ion Medical Accelerator in Chiba in Japan. Proton experiments are performed at the Lawrence Berkeley National Laboratory's 88'' Cyclotron with a 55 MeV beam, and at the Loma Linda University Proton Facility with 100 to 250 MeV beam energies. The experimental results are an important component of the overall shielding program, as they allow for simple, well-controlled tests of the models developed to handle the more complex radiation environment in space.

Zeitlin, Cary; Heilbronn, Lawrence; Miller, Jack; Wilson, John W.

2002-08-12

129

EXAMPLES OF RADIATION SHIELDING MODELS  

SciTech Connect

The attached pictures are examples of shielding models used by WSMS. The models were used in shielding evaluations for Tank 50 pump replacement. They show the relative location of shielding to radiation sources for pumps and pipes. None of the calculations that were associated with these models involved UCNI. The last page contains two pictures from a shielding calculation for the saltstone area. The upper picture is a conceptual drawing. The lower picture is an image copied from the website of a supplier for the project.

Willison, J

2006-07-27

130

Actively driven thermal radiation shield  

DOEpatents

A thermal radiation shield for cooled portable gamma-ray spectrometers. The thermal radiation shield is located intermediate the vacuum enclosure and detector enclosure, is actively driven, and is useful in reducing the heat load to mechanical cooler and additionally extends the lifetime of the mechanical cooler. The thermal shield is electrically-powered and is particularly useful for portable solid-state gamma-ray detectors or spectrometers that dramatically reduces the cooling power requirements. For example, the operating shield at 260K (40K below room temperature) will decrease the thermal radiation load to the detector by 50%, which makes possible portable battery operation for a mechanically cooled Ge spectrometer.

Madden, Norman W. (Livermore, CA); Cork, Christopher P. (Pleasant Hill, CA); Becker, John A. (Alameda, CA); Knapp, David A. (Livermore, CA)

2002-01-01

131

Analytical model of jet shielding  

NASA Technical Reports Server (NTRS)

An analytical model of the shielding of a stationary point noise source by a cylindrical jet is developed. The directivity function is derived which estimates the normalized sound pressure level at a far field receiver. The shielding model is compared to experimental data for a point noise source impinging on an unheated air jet and on a simulated hot air jet. The model compares favorably to measured shielding at receiver locations away from the jet axis. The trend of the estimated shielding diverges from the measured data as the jet axis is approached. Refinement of the model is discussed.

Gerhold, C. H.

1982-01-01

132

SHIELD verification and validation report  

SciTech Connect

This document outlines the verification and validation effort for the SHIELD, SHLDED, GEDIT, GENPRT, FIPROD, FPCALC, and PROCES modules of the SHIELD system code. Along with its predecessors, SHIELD has been in use at the Savannah River Site (SRS) for more than ten years. During this time the code has been extensively tested and a variety of validation documents have been issued. The primary function of this report is to specify the features and capabilities for which SHIELD is to be considered validated, and to reference the documents that establish the validation.

Boman, C.

1992-02-01

133

Hypervelocity impact shield  

NASA Technical Reports Server (NTRS)

A hypervelocity impact shield and method for protecting a wall structure, such as a spacecraft wall, from impact with particles of debris having densities of about 2.7 g/cu cm and impact velocities up to 16 km/s are disclosed. The shield comprises a stack of ultra thin sheets of impactor disrupting material supported and arranged by support means in spaced relationship to one another and mounted to cover the wall in a position for intercepting the particles. The sheets are of a number and spacing such that the impacting particle and the resulting particulates of the impacting particle and sheet material are successively impact-shocked to a thermal state of total melt and/or vaporization to a degree as precludes perforation of the wall. The ratio of individual sheet thickness to the theoretical diameter of particles of debris which may be of spherical form is in the range of 0.03 to 0.05. The spacing between adjacent sheets is such that the debris cloud plume of liquid and vapor resulting from an impacting particle penetrating a sheet does not puncture the next adjacent sheet prior to the arrival thereat of fragment particulates of sheet material and the debris particle produced by a previous impact.

Cour-Palais, Burton G. (inventor); Crews, Jeanne Lee (inventor)

1991-01-01

134

SHIELDING ANALYSES FOR THE HNPF FUEL ELEMENT SHIELD PLUGS  

Microsoft Academic Search

The shielding of the HNPF fuel element shield plug was analyzed and ; reviewed. The direct gamma radiation penetrating the fuel plug was 0.32 mr\\/hr. ; The dose rate due to the direct penetration by fast and thermal neutrons was ; negligible. Gamma radiation streaming up the 1\\/16-in. annular gap between the ; fuel plug and the cavity liner was

Bergar

1960-01-01

135

PBF Cubicle 13. Shield wall details illustrate shielding technique of ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF Cubicle 13. Shield wall details illustrate shielding technique of stepped penetrations and brick layout scheme for valve stem extension sleeve. Aerojet Nuclear Company. Date: May 1976. INEEL index no. 761-0620-00-400-195280 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

136

Drip Shield Emplacement Gantry Concept  

SciTech Connect

This design analysis has shown that, on a conceptual level, the emplacement of drip shields is feasible with current technology and equipment. A plan for drip shield emplacement was presented using a Drip Shield Transporter, a Drip Shield Emplacement Gantry, a locomotive, and a Drip Shield Gantry Carrier. The use of a Drip Shield Emplacement Gantry as an emplacement concept results in a system that is simple, reliable, and interfaces with the numerous other exising repository systems. Using the Waste Emplacement/Retrieval System design as a basis for the drip shield emplacement concept proved to simplify the system by using existing equipment, such as the gantry carrier, locomotive, Electrical and Control systems, and many other systems, structures, and components. Restricted working envelopes for the Drip Shield Emplacement System require further consideration and must be addressed to show that the emplacement operations can be performed as the repository design evolves. Section 6.1 describes how the Drip Shield Emplacement System may use existing equipment. Depending on the length of time between the conclusion of waste emplacement and the commencement of drip shield emplacement, this equipment could include the locomotives, the gantry carrier, and the electrical, control, and rail systems. If the exisiting equipment is selected for use in the Drip Shield Emplacement System, then the length of time after the final stages of waste emplacement and start of drip shield emplacement may pose a concern for the life cycle of the system (e.g., reliability, maintainability, availability, etc.). Further investigation should be performed to consider the use of existing equipment for drip shield emplacement operations. Further investigation will also be needed regarding the interfaces and heat transfer and thermal effects aspects. The conceptual design also requires further design development. Although the findings of this analysis are accurate for the assumptions made, further refinements of this analysis are needed as the project parameters change. The designs of the drip shield, the Emplacement Drift, and the other drip shield emplacement equipment all have a direct effect on the overall design feasibility.

Silva, R.A.; Cron, J.

2000-03-29

137

Design experience: CRBRP radiation shielding  

Microsoft Academic Search

The Clinch River Breeder Reactor Plant (CRBRP) is being designed as a fast breeder demonstration project in the U.S. Liquid Metal Fast Breeder Reactor (LMFBR) program. Radiation shielding design of the facility consists of a comprehensive design approach to assure compliance with design and government regulatory requirements. Studies conducted during the CRBRP design process involved the aspects of radiation shielding

R. K. Disney; T. C. Chan; F. G. Gallo; L. R. Hedgecock; C. A. McGinnis; G. N. Wrights

1978-01-01

138

Radiation Shielding Optimization on Mars  

NASA Technical Reports Server (NTRS)

Future space missions to Mars will require radiation shielding to be optimized for deep space transit and an extended stay on the surface. In deep space, increased shielding levels and material optimization will reduce the exposure from most solar particle events (SPE) but are less effective at shielding against galactic cosmic rays (GCR). On the surface, the shielding provided by the Martian atmosphere greatly reduces the exposure from most SPE, and long-term GCR exposure is a primary concern. Previous work has shown that in deep space, additional shielding of common materials such as aluminum or polyethylene does not significantly reduce the GCR exposure. In this work, it is shown that on the Martian surface, almost any amount of aluminum shielding increases exposure levels for humans. The increased exposure levels are attributed to neutron production in the shield and Martian regolith as well as the electromagnetic cascade induced in the Martian atmosphere. This result is significant for optimization of vehicle and shield designs intended for the surface of Mars.

Slaba, Tony C.; Mertens, Chris J.; Blattnig, Steve R.

2013-01-01

139

EMP coupling to shielded cables  

NASA Astrophysics Data System (ADS)

Electromagnetic coupling to shielded cables is analyzed in terms of two electromagnetically coupled transmission lines excited by distributed sources. This analysis results in two traveling waves on the shield and four traveling waves in the core of the cable. Transient waveforms are reported from EMP coupling on an overhead RG-58 cable.

Agouridis, D. C.

140

Galactic cosmic ray abundances and spectra behind defined shielding  

NASA Technical Reports Server (NTRS)

Linear Energy Transfer (LET) spectra have been measured for lunar missions and for several near Earth orbits ranging from 28 deg to 83 deg inclination. In some of the experiments the flux of Galactic Cosmic Rays (GCR) was determined separately from contributions caused by interactions in the detector material. Results of these experiments are compared to model calculations. The general agreement justifies the use of the model to calculate GCR fluxes. The magnitude of variations caused by solar modulation, geomagnetic shielding, and shielding by matter determined from calculated LET spectra is generally in agreement with experimental data. However, more detailed investigations show that there are some weak points in modeling solar modulation and shielding by material. These points are discussed in more detail.

Heinrich, W.; Benton, E. V.; Wiegel, B.; Zens, R.; Rusch, G.

1994-01-01

141

A Radiation Shielding Code for Spacecraft and Its Validation  

NASA Technical Reports Server (NTRS)

The HZETRN code, which uses a deterministic approach pioneered at NASA Langley Research Center, has been developed over the past decade to evaluate the local radiation fields within sensitive materials (electronic devices and human tissue) on spacecraft in the space environment. The code describes the interactions of shield materials with the incident galactic cosmic rays, trapped protons, or energetic protons from solar particle events in free space and low Earth orbit. The content of incident radiations is modified by atomic and nuclear reactions with the spacecraft and radiation shield materials. High-energy heavy ions are fragmented into less massive reaction products, and reaction products are produced by direct knockout of shield constituents or from de-excitation products. An overview of the computational procedures and database which describe these interactions is given. Validation of the code with recent Monte Carlo benchmarks, and laboratory and flight measurement is also included.

Shinn, J. L.; Cucinotta, F. A.; Singleterry, R. C.; Wilson, J. W.; Badavi, F. F.; Badhwar, G. D.; Miller, J.; Zeitlin, C.; Heilbronn, L.; Tripathi, R. K.

2000-01-01

142

Portable convertible blast effects shield  

DOEpatents

A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more frusto-conically-tapered telescoping rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration by the friction fit of adjacent pairs of frusto-conically-tapered rings to each other.

Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler, Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A. (Livermore, CA)

2011-03-15

143

Welding shield for coupling heaters  

DOEpatents

Systems for coupling end portions of two elongated heater portions and methods of using such systems to treat a subsurface formation are described herein. A system may include a holding system configured to hold end portions of the two elongated heater portions so that the end portions are abutted together or located near each other; a shield for enclosing the end portions, and one or more inert gas inlets configured to provide at least one inert gas to flush the system with inert gas during welding of the end portions. The shield may be configured to inhibit oxidation during welding that joins the end portions together. The shield may include a hinged door that, when closed, is configured to at least partially isolate the interior of the shield from the atmosphere. The hinged door, when open, is configured to allow access to the interior of the shield.

Menotti, James Louis (Dickinson, TX)

2010-03-09

144

Portable convertible blast effects shield  

SciTech Connect

A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler,; Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)

2010-10-26

145

Portable convertible blast effects shield  

DOEpatents

A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler, Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)

2007-05-22

146

Analytic Ballistic Performance Model of Whipple Shields  

NASA Technical Reports Server (NTRS)

The dual-wall Whipple shield is the shield of choice for lightweight, long-duration flight. The shield uses an initial sacrificial wall to initiate fragmentation and melt an impacting threat that expands over a void before hitting a subsequent shield wall of a critical component. The key parameters to this type of shield are the rear wall and its mass which stops the debris, as well as the minimum pressure generated under threat particle impact of the sacrificial wall and the amount of void that is available for expansion. Ensuring the minimum pressure is sufficiently high to achieve large scale fragmentation/melt of the threat particle enables the expansion of the threat and reduces the momentum flux of the debris on the rear wall. Three key factors in the minimum pressure achieved are the thickness of the sacrificial wall relative to the characteristic dimension of the impacting particle, the density and material cohesion contrast of the sacrificial wall relative to the threat particle and the impact speed. The mass of the rear wall and the sacrificial wall are desirable to minimize for launch costs and dynamic concerns making it important to have an understanding of the effects of density contrast and impact speed. In this paper a fourth key parameter is identified related to fragmentation, which corresponds to the ratio of the size of the projectile relative to the transition from brittle to ductile hole growth in the projectile. Ballistic limit equations have been developed to define the failure limits of a MMOD shield, generally in terms of projectile diameter (or mass), impact velocity, and angle. Within the range of impact velocities relevant for Earth-orbiting spacecraft, three distinct regions of penetration phenomenology have been identified for Whipple shields: center dot Low velocity: the projectile is eroded (and possibly deformed) during its passage through the bumper plate, but is not fragmented. Thus, perforation of the rear wall is by a fragment with a mass and speed equal to or less than the original impactor. center dot Intermediate (shatter) velocity: impact velocities are sufficient to induce projectile fragmentation upon impact with the bumper plate, resulting in a coarse debris cloud with large solid fragments. Increasing velocity within the shatter regime results in increased fragmentation, and eventually melting, of the projectile and bumper fragments, generating a finer and more evenly dispersed debris cloud. Failure of the rear wall is a complicated combination of modes observed at low- and hypervelocity. center dot Hypervelocity: the projectile and holed-out bumper material is completely, or nearly completely, melted and/or vaporized by the initial impact. The resultant debris cloud impacts over a dispersed area of the rear wall, loading it impulsively and inducing failure through rupture or petalling. While each of these regimes are well observed with extensive empirical methods to describe these regions, differences in impactor materials, configurations of shields and questions about the limitations of the attainable impact speeds have left questions that are difficult to answer from completely empirical methods.

Miller, J. E.; Bjorkman, M. D.; Christiansen, E. L.; Ryan, S. J.

2014-01-01

147

Shielded enclosures for experimental studies of shielding topology  

NASA Astrophysics Data System (ADS)

The report discusses the effort to provide shielded enclosures for EMP experimental studies of shielding topology. Section 1 discusses the theoretical modeling for which scattering matrices of subshields and their norms are used to relate the internal signals to the electromagnetic source environment. Both the line and aperture penetrations are included in the scattering matrix formulation. Experimental and analytical methods are proposed for estimating parameters of the scattering matrices. It is pointed out in the discussion that these methods can, in turn, be employed to analyze the overall shielding performance and to synthesize the subshield requirements of a system. The discussion in Section 1 includes an illustrative example. Section 2 describes experiments to characterize and quantify the shielding performance of a rectangular metal enclosure containing various line and aperture penetrations. Experimental techniques and procedures are given for obtaining certain parameters involved in the theoretical model for bounding the shielding performance of an enclosure. Techniques for evaluation of the accuracy of the theoretical calculation and its comparison to measured data are also discussed. Section 3 describes specifications that were developed to construct two shielded enclosures, one with a single layer topology and one with a double layer topology. Details are given on the mechanical design of the two enclosures, and on the design of various replaceable panels that can be used to test the accuracy of the theoretical model. Section 4 describes the experimental results of the shielding performance of the two enclosures constructed by SRI International.

Yang, F. C.; Lee, K. S. H.; Kokorowski, S. A.; Baum, C. E.; Hamm, J.; Graf, W.; Vance, E. F.

1984-11-01

148

Preliminary design of magnetic shielding by FEM  

SciTech Connect

In this paper, the authors propose an optimization method for magnetic shielding. The main purpose is the weight reduction of shield material. Assuming that the permeability of shield material is infinite, they simplify the magnetic shielding problem. Under this assumption, they design optimal passage for magnetic flux through the shield. They apply this method to designing the magnetic shielding for Maglev and show the effectiveness of this method by experimental and numerical data.

Sasakawa, Takashi; Tagawa, Naoto; Herai, Toshiki; Tomita, Masaru [Railway Technical Research Inst., Kokubunji, Tokyo (Japan)] [Railway Technical Research Inst., Kokubunji, Tokyo (Japan)

1997-03-01

149

Lunar Surface Reactor Shielding Study  

NASA Astrophysics Data System (ADS)

A nuclear reactor system could provide power to support long term human exploration of the moon. Such a system would require shielding to protect astronauts from its emitted radiations. Shielding studies have been performed for a Gas Cooled Reactor system because it is considered to be the most suitable nuclear reactor system available for lunar exploration, based on its tolerance of oxidizing lunar regolith and its good conversion efficiency. The goals of the shielding studies were to determine a material shielding configuration that reduces the dose (rem) to the required level in order to protect astronauts, and to estimate the mass of regolith that would provide an equivalent protective effect if it were used as the shielding material. All calculations were performed using MCNPX, a Monte Carlo transport code. Lithium hydride must be kept between 600 K and 700 K to prevent excessive swelling from large amounts of gamma or neutron irradiation. The issue is that radiation damage causes separation of the lithium and the hydrogen, resulting in lithium metal and hydrogen gas. The proposed design uses a layer of B4C to reduce the combined neutron and gamma dose to below 0.5Grads before the LiH is introduced. Below 0.5Grads the swelling in LiH is small (less than about 1%) for all temperatures. This approach causes the shield to be heavier than if the B4C were replaced by LiH, but it makes the shield much more robust and reliable.

Kang, Shawn; Lipinski, Ronald; McAlpine, William

2006-01-01

150

Radiation Exposure Effects and Shielding Analysis of Carbon Nanotube Materials  

NASA Technical Reports Server (NTRS)

Carbon nanotube materials promise to be the basis for a variety of emerging technologies with aerospace applications. Potential applications to human space flight include spacecraft shielding, hydrogen storage, structures and fixtures and nano-electronics. Appropriate risk analysis on the properties of nanotube materials is essential for future mission safety. Along with other environmental hazards, materials used in space flight encounter a hostile radiation environment for all mission profiles, from low earth orbit to interplanetary space.

Wilkins, Richard; Armendariz, Lupita (Technical Monitor)

2002-01-01

151

Hot-Water Worms May Use Bacteria as Shield  

NSDL National Science Digital Library

This National Geographic news article highlights research being done to study the Pompeii worm (Alvinella pompejana), the most heat tolerant complex organism on Earth, and its microscopic symbionts. Bacteria on the worms' backs act like firefighters' blankets, shielding the worms from intermittent blasts of hot, metal-rich water. Scientists are currently characterizing the chemistry of the vent environment by sequencing a large amount of DNA from the bacterial community-the metagenome. The page includes links to related National Geographic sites.

Roach, John

2009-06-17

152

Spacecraft Shielding: An Experimental Comparison Between Open Cell Aluminium Foam Core Sandwich Panel Structures and Whipple Shielding.  

NASA Astrophysics Data System (ADS)

Spacecraft shielding is generally provided by metallic plates in a Whipple shield type configuration [1] where possible. However, mission restrictions such as spacecraft payload mass, can prevent the inclusion of a dedicated protective structure for prevention against impact damage from micrometeoroids. Due to this, often the spacecraft's primary structure will act as the de facto shield. This is commonly an aluminium honeycomb backed with either glass fibre reinforced plastic (GFRP) or aluminium faceplates [2]. Such materials are strong, lightweight and relatively cheap due to their abundance used within the aerospace industry. However, these materials do not offer the best protection (per unit weight) against hypervelocity impact damage. A new material for shielding (porous aluminium foam [3]) is suggested for low risk space missions. Previous studies by NASA [4] have been performed to test this new material against hypervelocity impacts using spherical aluminium projectiles. This showed its potential for protection for satellites in Earth orbit, against metallic space debris. Here we demonstrate the material's protective capabilities against micrometeoroids, using soda-lime glass spheres as projectiles to accurately gauge its potential with relation to silicatious materials, such as micrometeoroids and natural solar system debris. This is useful for spacecraft missions beyond Earth orbit where solar system materials are the dominant threat (via hypervelocity impacts) to the spacecraft, rather than manmade debris.

Pasini, D. L. S.; Price, M. C.; Burchell, M. J.; Cole, M. J.

2013-09-01

153

New Materials for EMI Shielding  

NASA Technical Reports Server (NTRS)

Graphite fibers intercalated with bromine or similar mixed halogen compounds have substantially lower resistivity than their pristine counterparts, and thus should exhibit higher shielding effectiveness against electromagnetic interference. The mechanical and thermal properties are nearly unaffected, and the shielding of high energy x-rays and gamma rays is substantially increased. Characterization of the resistivity of the composite materials is subtle, but it is clear that the composite resistivity is substantially lowered. Shielding effectiveness calculations utilizing a simple rule of mixtures model yields results that are consistent with available data on these materials.

Gaier, James R.

1999-01-01

154

A Brief History of Meteoroid and Orbital Debris Shielding Technology for US Manned Spacecraft  

NASA Technical Reports Server (NTRS)

Meteoroid and orbital debris shielding has played an important role from the beginning of manned spaceflight. During the early 60 s, meteoroid protection drove requirements for new meteor and micrometeoroid impact science. Meteoroid protection also stimulated advances in the technology of hypervelocity impact launchers and impact damage assessment methodologies. The first phase of meteoroid shielding assessments closed in the early 70 s with the end of the Apollo program. The second phase of meteoroid protection technology began in the early 80 s when it was determined that there is a manmade Earth orbital debris belt that poses a significant risk to LEO manned spacecraft. The severity of the Earth orbital debris environment has dictated changes in Space Shuttle and ISS operations as well as driven advances in shielding technology and assessment methodologies. A timeline of shielding technology and assessment methodology advances is presented along with a summary of risk assessment results.

Bjorkman, Michael D.; Hyde, James L.

2008-01-01

155

Hubble Space Telescope Bi-Stem Thermal Shield Analyses  

NASA Technical Reports Server (NTRS)

The Hubble Space Telescope (HST) was launched April 24, 1990, and was deployed April 25 into low Earth orbit (LEO). It was soon discovered that the metal poles holding the solar arrays were expanding and contracting as the telescope orbited the Earth passing between the sunlight and the Earth s shadow. The expansion and contraction, although very small, was enough to cause the telescope to shake because of thermal-induced jitters, a detrimental effect when trying to take pictures millions of miles away. Therefore, the European Space Agency (ESA, the provider of the solar arrays) built new solar arrays (SA-11) that contained bi-stem thermal shields which insulated the solar array metal poles. These thermal shields were made of 2 mil thick aluminized-Teflon fluorinated ethylene propylene (FEP) rings fused together into a circular bellows shape. The new solar arrays were put on the HST during an extravehicular activity (EVA), also called an astronaut space walk, during the first servicing mission (SM1) in December 1993. An on-orbit photograph of the HST with the SA-11, and a close up of the bellows-like structure of the thermal shields is provided in Figure 1.

Finlay, Katherine A.

2004-01-01

156

Large Magnetic Shielding Factor Measured by Nonlinear Magneto-optical Rotation  

E-print Network

A passive magnetic shield was designed and constructed for magnetometer tests for the future neutron electric dipole moment experiment at TRIUMF. The axial shielding factor of the magnetic shield was measured using a magnetometer based on non-linear magneto-optical rotation of the plane of polarized laser light upon passage through a paraffin-coated vapour cell containing natural Rb at room temperature. The laser was tuned to the Rb D1 line, near the $^{85}$Rb $F=2\\rightarrow 2,3$ transition. The shielding factor was measured by applying an axial field externally and measuring the magnetic field internally using the magnetometer. The axial shielding factor was determined to be $(1.3\\pm 0.1)\\times 10^{7}$, from an applied axial field of 1.45~$\\mu$T in the background of Earth's magnetic field.

Jeffery W. Martin; Russell R. Mammei; Wolfgang Klassen; Cameron Cerasani; Taraneh Andalib; Christopher P. Bidinosti; Michael Lang; David Ostapchuk

2014-11-07

157

Design of Cassegrain light shields.  

PubMed

A Fortran program has been written for the optimum design of light shields for Cassegrain optical systems with finite field. The techniques employed are described, and results are shown. PMID:20062125

Young, A T

1967-06-01

158

Structural/Radiation-Shielding Epoxies  

NASA Technical Reports Server (NTRS)

A development effort was directed toward formulating epoxy resins that are useful both as structural materials and as shielding against heavy-ion radiation. Hydrogen is recognized as the best element for absorbing heavy-ion radiation, and high-hydrogen-content polymers are now in use as shielding materials. However, high-hydrogen-content polymers (e.g. polyethylene) are typically not good structural materials. In contrast, aromatic polymers, which contain smaller amounts of hydrogen, often have the strength necessary for structural materials. Accordingly, the present development effort is based on the concept that an ideal structural/ heavy-ion-radiation-shielding material would be a polymer that contains sufficient hydrogen (e.g., in the form of aliphatic molecular groups) for radiation shielding and has sufficient aromatic content for structural integrity.

Connell, John W.; Smith, Joseph G.; Hinkley, Jeffrey; Blattnig, Steve; Delozier, Donavon M.; Watson, Kent A.; Ghose, Sayata

2009-01-01

159

Radiation Shielding and Radiological Protection  

E-print Network

Radiation Shielding and Radiological Protection J. Kenneth Shultis Richard E. Faw Department@triad.rr.com Radiation Fields and Sources ................................................ . Radiation Field Variables........................................................... .. Direction and Solid Angle Conventions ......................................... .. Radiation Fluence

Shultis, J. Kenneth

160

Composite Aerogel Multifoil Protective Shielding  

NASA Technical Reports Server (NTRS)

New technologies are needed to survive the temperatures, radiation, and hypervelocity particles that exploration spacecraft encounter. Multilayer insulations (MLIs) have been used on many spacecraft as thermal insulation. Other materials and composites have been used as micrometeorite shielding or radiation shielding. However, no material composite has been developed and employed as a combined thermal insulation, micrometeorite, and radiation shielding. By replacing the scrims that have been used to separate the foil layers in MLIs with various aerogels, and by using a variety of different metal foils, the overall protective performance of MLIs can be greatly expanded to act as thermal insulation, radiation shielding, and hypervelocity particle shielding. Aerogels are highly porous, low-density solids that are produced by the gelation of metal alkoxides and supercritical drying. Aerogels have been flown in NASA missions as a hypervelocity particle capture medium (Stardust) and as thermal insulation (2003 MER). Composite aerogel multifoil protective shielding would be used to provide thermal insulation, while also shielding spacecraft or components from radiation and hypervelocity particle impacts. Multiple layers of foil separated by aerogel would act as a thermal barrier by preventing the transport of heat energy through the composite. The silica aerogel would act as a convective and conductive thermal barrier, while the titania powder and metal foils would absorb and reflect the radiative heat. It would also capture small hypervelocity particles, such as micrometeorites, since it would be a stuffed, multi-shock Whipple shield. The metal foil layers would slow and break up the impacting particles, while the aerogel layers would convert the kinetic energy of the particles to thermal and mechanical energy and stop the particles.

Jones, Steven M.

2013-01-01

161

Magnetic Shield for Adiabatic Demagnetization Refrigerators (ADR)  

NASA Technical Reports Server (NTRS)

A new method was developed for creating a less expensive shield for ADRs using 1018 carbon steel. This shield has been designed to have similar performance to the expensive vanadium permendur shields, but the cost is 30 to 50% less. Also, these shields can be stocked in a variety of sizes, eliminating the need for special forgings, which also greatly reduces cost.

Chui, Talso C.; Haddad, Nicolas E.

2013-01-01

162

THE PLUTONIUM RECYCLE TEST REACTOR SHIELDING EVALUATION  

Microsoft Academic Search

The x-ray film studies of the top and bottom primary shields displayed ; definlte gamma radiation streaming from around the shim control shroud tubes, ; monitor tubes, and other access holes, but showed effective shielding above and ; below the process tubes and primary shields. The biological shielding displayed ; no leaks or weak spots except for areas around all

1962-01-01

163

Transient heat flux shielding using thermal metamaterials  

NASA Astrophysics Data System (ADS)

We have developed a heat shield based on a metamaterial engineering approach to shield a region from transient diffusive heat flow. The shield is designed with a multilayered structure to prescribe the appropriate spatial profile for heat capacity, density, and thermal conductivity of the effective medium. The heat shield was experimentally compared to other isotropic materials.

Narayana, Supradeep; Savo, Salvatore; Sato, Yuki

2013-05-01

164

SHIELDING THE ENRICO FERMI FAST BREEDER REACTOR  

Microsoft Academic Search

The solution of the shielding problems encountered in the Enrico Fermi ; Reactor are given. The shield has been designed from common materials whose ; durability over the expected life of the plant is known and whose cost is low. ; These are graphite, steel, and concrete, all used in the primary, secondary, and ; biological shields. Special shields are

H. E. Hungerford; R. F. Mantey

1958-01-01

165

Thermal neutron shield and method of manufacture  

DOEpatents

A thermal neutron shield comprising boron shielding panels with a high percentage of the element Boron. The panel is least 46% Boron by weight which maximizes the effectiveness of the shielding against thermal neutrons. The accompanying method discloses the manufacture of boron shielding panels which includes enriching the pre-cursor mixture with varying grit sizes of Boron Carbide.

Metzger, Bert Clayton; Brindza, Paul Daniel

2014-03-04

166

An Analysis of Ablation-Shield Requirements for Manned Reentry Vehicles  

NASA Technical Reports Server (NTRS)

The problem of sublimation of material and accumulation of heat in an ablation shield is analyzed and the results are applied to the reentry of manned vehicles into the earth's atmosphere. The parameters which control the amount of sublimation and the temperature distribution within the ablation shield are determined and presented in a manner useful for engineering calculation. It is shown that the total mass loss from the shield during reentry and the insulation requirements may be given very simply in terms of the maximum deceleration of the vehicle or the total reentry time.

Roberts, Leonard

1960-01-01

167

Evidence for an extensive Phanerozoic sediment cover on the Canadian and Fenno-Scandian shields  

SciTech Connect

Examination of the age and diameter of 75 terrestrial meteorite impact craters taken from platform and shield regions throughout the world suggest that both the Canadian and Fenno-Scandian Shields were covered by a sedimentary blanket during a portion of the Phanerozoic. Subsequent erosion, fostered perhaps by a combination of glacial and tectonic processes, has exposed both of these shields to reveal an anomalous distribution of craters through time. The primary evidence for sedimentary cover and subsequent erosion is in the form of a 280 Myr gap in the record of craters less than 15 km in diameter. Small craters of Cambrian, Ordovician and Silurian age are found in shield regions, suggesting either a thin or non-existent sediment cover during this period. However, there is no record of small diameter craters on either shield of Devonian, Carboniferous, Permian, Triassic, or Jurassic age (400 to 120 Myr). This 280 Myr gap suggests that the shields were protected from smaller body impacts by a sedimentary cover. In contrast, the record of impacts on platform sediments implies no such hiatus in the infall of cosmic bodies to the earth's surface between the Devonian and the Early Cretaceous. Subsequent erosion, perhaps by Early Cretaceous time, exposed the shields to further bombardment. In addition, pre-Devonian craters became exhumed. Thus, the record of impact craters suggests that the Canadian and Fenno-Scandian Shields were covered by sediments while part of Pangaea.

Laine, E.P.; Dickson, S.M.

1985-01-01

168

Radiation shielding materials and containers incorporating same  

DOEpatents

An improved radiation shielding material and storage systems for radioactive materials incorporating the same. The PYRolytic Uranium Compound ("PYRUC") shielding material is preferably formed by heat and/or pressure treatment of a precursor material comprising microspheres of a uranium compound, such as uranium dioxide or uranium carbide, and a suitable binder. The PYRUC shielding material provides improved radiation shielding, thermal characteristic, cost and ease of use in comparison with other shielding materials. The shielding material can be used to form containment systems, container vessels, shielding structures, and containment storage areas, all of which can be used to house radioactive waste. The preferred shielding system is in the form of a container for storage, transportation, and disposal of radioactive waste. In addition, improved methods for preparing uranium dioxide and uranium carbide microspheres for use in the radiation shielding materials are also provided.

Mirsky, Steven M. (Greenbelt, MD); Krill, Stephen J. (Arlington, VA); Murray, Alexander P. (Gaithersburg, MD)

2005-11-01

169

Radiation Shielding Materials and Containers Incorporating Same  

DOEpatents

An improved radiation shielding material and storage systems for radioactive materials incorporating the same. The PYRolytic Uranium Compound (''PYRUC'') shielding material is preferably formed by heat and/or pressure treatment of a precursor material comprising microspheres of a uranium compound, such as uranium dioxide or uranium carbide, and a suitable binder. The PYRUC shielding material provides improved radiation shielding, thermal characteristic, cost and ease of use in comparison with other shielding materials. The shielding material can be used to form containment systems, container vessels, shielding structures, and containment storage areas, all of which can be used to house radioactive waste. The preferred shielding system is in the form of a container for storage, transportation, and disposal of radioactive waste. In addition, improved methods for preparing uranium dioxide and uranium carbide microspheres for use in the radiation shielding materials are also provided.

Mirsky, Steven M.; Krill, Stephen J.; and Murray, Alexander P.

2005-11-01

170

Analysis of a Lunar Base Electrostatic Radiation Shield Concept  

NASA Technical Reports Server (NTRS)

Space weather can be defined as the total ensemble of radiation in space, as well as on the surface of moons and asteroids. It consists of electromagnetic, charged-particle, and neutral particle radiation. The fundamental goal behind this NIAC Phase I research is to investigate methods of generating a static electric-field potential phi(x, y, z) in the volume above and around a "safe" or protected area on the lunar surface so that trajectories of harmful charged particle radiation are modified (deflected or reflected), thus creating a shadow over that region. Since the charged particles are not neutralized but merely redirected, there will be areas outside of the shadowed protected region that will have a higher flux concentration of radiation. One of the fundamental limitations of the static electric (electrostatic)-field approach to radiation shielding is that complete shadowing is accomplished only by complete reflection, which can only occur for shield voltages greater than or equal to the kinetic energy (in electron volts) of the incoming charged particles. Just as habitats on Earth are protected from severe weather events and conditions, such as extreme temperatures, high winds, and UV radiation, using multiple methods of shielding protection from severe space weather will undoubtedly require multiple strategies. The electrostatic shield concept may be one of many methods employed to protect astronaut habitats on the lunar surface from some of the harmful effects of space weather.

Buhler, Charles R.

2004-01-01

171

Earth's Atmosphere  

NSDL National Science Digital Library

This problem set is about the methods scientists use to compare the abundance of the different elements in Earth's atmosphere. Answer key is provided. This is part of Earth Math: A Brief Mathematical Guide to Earth Science and Climate Change.

172

Earth's Three  

E-print Network

Broadcast Transcript: From Mongolia, land of fermented mare's milk, comes this beguiling morsel of nomadic oral tradition. It's called yertonciin gorav or Earth's Three. Earth's three what? Well, Earth's three top things in a number of categories...

Hacker, Randi

2010-11-17

173

Earth Sciences Environmental Earth Sciences,  

E-print Network

84 Earth Sciences­ Environmental Earth Sciences, Geology MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint Honours Degrees) and among the most research-intensive in Europe. Features * The Department of Earth and Environmental

Brierley, Andrew

174

Earth Sciences Environmental Earth Sciences,  

E-print Network

94 Earth Sciences­ Environmental Earth Sciences, Geology Degree options MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint placement. * The Geology and Environmental Earth Sciences degrees are accredited by the Geological Society

Brierley, Andrew

175

Shielding vacuum fluctuations with graphene  

E-print Network

The Casimir-Polder interaction of ground-state and excited atoms with graphene is investigated with the aim to establish whether graphene systems can be used as a shield for vacuum fluctuations of an underlying substrate. We calculate the zero-temperature Casimir-Polder potential from the reflection coefficients of graphene within the framework of the Dirac model. For both doped and undoped graphene we show limits at which graphene could be used effectively as a shield. Additional results are given for AB-stacked bilayer graphene.

Sofia Ribeiro; Stefan Scheel

2014-03-14

176

The Embedded Self-Shielding Method  

SciTech Connect

The embedded self-shielding method (ESSM) is described for computing resonance-shielded cross sections used in multigroup neutron transport calculations with the SCALE code system. The ESSM - embeds the self-shielding computation within the transport solution. The transport solution provides information for treating heterogeneous self-shielding effects, and the resulting shielded cross sections are fed back to the transport calculation. Iterations are done to obtain self-consistency. This allows self-shielded cross sections to be generated directly in the transport geometry without requiring external computation of Dancoff factors. The ESSM theory and example calculations are presented.

Williams, Mark L [ORNL; Kim, Kang Seog [ORNL

2012-01-01

177

Regolith Derived Heat Shield for Planetary Body Entry and Descent System with In Situ Fabrication  

NASA Technical Reports Server (NTRS)

This NIAC project investigated an innovative approach to provide heat shield protection to spacecraft after launch and prior to each EDL thus potentially realizing significant launch mass savings. Heat shields fabricated in situ can provide a thermal-protection system for spacecraft that routinely enter a planetary atmosphere. By fabricating the heat shield with space resources from materials available on moons and asteroids, it is possible to avoid launching the heat-shield mass from Earth. Regolith has extremely good insulating properties and the silicates it contains can be used in the fabrication and molding of thermal-protection materials. Such in situ developed heat shields have been suggested before by Lewis. Prior research efforts have shown that regolith properties can be compatible with very-high temperature resistance. Our project team is highly experienced in regolith processing and thermal protection systems (TPS). Routine access to space and return from any planetary surface requires dealing with heat loads experienced by the spacecraft during reentry. Our team addresses some of the key issues with the EDL of human-scale missions through a highly innovative investigation of heat shields that can be fabricated in space by using local resources on asteroids and moons. Most space missions are one-way trips, dedicated to placing an asset in space for economical or scientific gain. However, for human missions, a very-reliable heat-shield system is necessary to protect the crew from the intense heat experienced at very high entry velocities of approximately 11 km/s at approximately Mach 33 (Apollo). For a human mission to Mars, the return problem is even more difficult, with predicted velocities of up to 14 km/s, at approximately Mach 42 at the Earth-atmosphere entry. In addition to human return, it is very likely that future space-travel architecture will include returning cargo to the Earth, either for scientific purposes or for commercial reasons. Platinum, titanium, helium 3, and other metals, elements and minerals are all high-value commodities in limited supply on Earth, and it may be profitable to mine these substances throughout the Solar System and return them to Earth, if an economical method can be found. To date, several private corporations have been launched to pursue these goals. Because the heat shield is the last element to be used in an Earth-return mission, a high penalty is paid in the propellant mass required to carry the heat shield to the destination and back. If the heat shield could be manufactured in space, and then outfitted on the spacecraft prior to the reentry at Earth, then significant propellant and mass savings could be achieved during launch and space operations. Preliminary mission architecture scenarios are described, which explain the potential benefits that may be derived from using an in-situ fabricated regolith heat shield. In order to prove that this is a feasible technology concept, this project successfully fabricated heat shield materials from mineral simulant materials of lunar and Martian regolith by two methods: 1) Sintering and 2) Binding the simulant with a "room-temperature vulcanizing" (RTV) silicone formulated to withstand high temperatures. Initially a third type of fabrication was planned using the hot waste stream from regolith ISRU processes. This fabrication method was discarded since the resulting samples would be too dense and brittle for heat shields. High temperature flame tests at KSC and subsequent arc jet tests at Ames Research Center (ARC) have proved promising. These coupon tests show favorable materials properties and have the potential to be a new way of fabricating heat shields for space entry into planetary atmospheres.

Hogue, Michael D.; Meuller, Robert P.; Sibille, Laurent; Hintze, Paul E.; Rasky, Daniel J.

2012-01-01

178

Regolith Derived Heat Shield for Planetary Body Entry and Descent System with In Situ Fabrication  

NASA Technical Reports Server (NTRS)

This NIAC project investigated an innovative approach to provide heat shield protection to spacecraft after launch and prior to each EDL thus potentially realizing significant launch mass savings. Heat shields fabricated in situ can provide a thermal-protection system for spacecraft that routinely enter a planetary atmosphere. By fabricating the heat shield with space resources from materials available on moons and asteroids, it is possible to avoid launching the heat-shield mass from Earth. Regolith has extremely good insulating properties and the silicates it contains can be used in the fabrication and molding of thermal-protection materials. Such in situ developed heat shields have been suggested before by Lewis. Prior research efforts have shown that regolith properties can be compatible with very-high temperature resistance. Our project team is highly experienced in regolith processing and thermal protection systems (TPS). Routine access to space and return from any planetary surface requires dealing with heat loads experienced by the spacecraft during reentry. Our team addresses some of the key issues with the EDL of human-scale missions through a highly innovative investigation of heat shields that can be fabricated in space by using local resources on asteroids and moons. Most space missions are one-way trips, dedicated to placing an asset in space for economical or scientific gain. However, for human missions, a very-reliable heat-shield system is necessary to protect the crew from the intense heat experienced at very high entry velocities of approximately 11 km/s at approximately Mach 33 (Apollo). For a human mission to Mars, the return problem is even more difficult, with predicted velocities of up to 14 km/s, at approximately Mach 42 at the Earth-atmosphere entry. In addition to human return, it is very likely that future space-travel architecture will include returning cargo to the Earth, either for scientific purposes or for commercial reasons. Platinum, titanium, helium 3, and other metals, elements and minerals are all high-value commodities in limited supply on Earth, and it may be profitable to mine these substances throughout the Solar System and return them to Earth, if an economical method can be found. To date, several private corporations have been launched to pursue these goals. Because the heat shield is the last element to be used in an Earth-return mission, a high penalty is paid in the propellant mass required to carry the heat shield to the destination and back. If the heat shield could be manufactured in space, and then outfitted on the spacecraft prior to the reentry at Earth, then significant propellant and mass savings could be achieved during launch and space operations. Preliminary mission architecture scenarios are described, which explain the potential benefits that may be derived from using an in-situ fabricated regolith heat shield. In order to prove that this is a feasible technology concept, this project successfully fabricated heat shield materials from mineral simulant materials of lunar and Martian regolith by two methods: 1) Sintering and 2) Binding the simulant with a "room-temperature vulcanizing" (RTV) silicone formulated to withstand high temperatures. Initially a third type of fabrication was planned using the hot waste stream from regolith ISRU processes. This fabrication method was discarded since the resulting samples would be too dense and brittle for heat shields. High temperature flame tests at KSC and subsequent arc jet tests at Ames Research Center (ARC) have proved promising. These coupon tests show favorable materials properties and have the potential to be a new way of fabricating heat shields for space entry into planetary atmospheres.

Hogue, Michael D.; Mueller, Robert P.; Sibille, Laurent; Hintze, Paul E.; Rasky, Daniel J.

2013-01-01

179

6500 Staticide ESD Safety Shield  

E-print Network

aerosol spray can; 12 per case. Note: This formula is available in quarts or gal- lons as a liquid. Get true long-lasting* ESD protection in an aerosol spray! The reliable performance of Staticide® ESD Safety Shield is now available in a convenient aerosol spray. This static electricity prob- lem solver

Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

180

Material Effectiveness for Radiation Shielding  

NASA Technical Reports Server (NTRS)

Materials with a smaller mean atomic mass, such as lithium (Li) hydride and polyethylene, make the best radiation shields for astronauts. The materials have a higher density of nuclei and are better able to block incoming radiation. Also, they tend to produce fewer and less dangerous secondary particles after impact with incoming radiation.

2003-01-01

181

Improved space radiation shielding methods  

NASA Technical Reports Server (NTRS)

The computing software that was used to perform the charged particle radiation transport analysis and shielding design for the Mariner Jupiter/Saturn 1977 spacecraft is described. Electron fluences, energy spectra and dose rates obtained with this software are presented and compared with independent computer calculations.

Davis, H. S.; Jordan, T. M.

1976-01-01

182

Combustor bulkhead heat shield assembly  

Microsoft Academic Search

This paper describes a gas turbine engine having an annular combustion chamber defined by an annular, inner liner, a concentric outer liner, and an upstream annular combustor head, wherein the head includes a radially extending bulkhead having circumferentially distributed openings for each receiving an individual fuel nozzle therethrough. It comprises: a segmented heat shield assembly, disposed between the combustion chamber

Zeisser

1990-01-01

183

10 CFR 36.25 - Shielding.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 false Shielding. 36.25 Section 36...REGULATORY COMMISSION LICENSES AND RADIATION SAFETY REQUIREMENTS FOR IRRADIATORS...for Irradiators § 36.25 Shielding. (a) The radiation dose rate in...

2011-01-01

184

10 CFR 36.25 - Shielding.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 false Shielding. 36.25 Section 36...REGULATORY COMMISSION LICENSES AND RADIATION SAFETY REQUIREMENTS FOR IRRADIATORS...for Irradiators § 36.25 Shielding. (a) The radiation dose rate in...

2012-01-01

185

10 CFR 36.25 - Shielding.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 false Shielding. 36.25 Section 36...REGULATORY COMMISSION LICENSES AND RADIATION SAFETY REQUIREMENTS FOR IRRADIATORS...for Irradiators § 36.25 Shielding. (a) The radiation dose rate in...

2014-01-01

186

10 CFR 36.25 - Shielding.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 false Shielding. 36.25 Section 36...REGULATORY COMMISSION LICENSES AND RADIATION SAFETY REQUIREMENTS FOR IRRADIATORS...for Irradiators § 36.25 Shielding. (a) The radiation dose rate in...

2013-01-01

187

Rotary stripper for shielded and unshielded FCC  

NASA Technical Reports Server (NTRS)

Rotary stripper removes narrow strips of insulation and shielding to any desired depth. Unshielded cables are stripped on both sides with one stroke, shielded cables are stripped in steps of different depths.

Angele, W.; Chambers, C. M.

1971-01-01

188

Reliability-Based Electronics Shielding Design Tools  

NASA Technical Reports Server (NTRS)

Shielding design on large human-rated systems allows minimization of radiation impact on electronic systems. Shielding design tools require adequate methods for evaluation of design layouts, guiding qualification testing, and adequate follow-up on final design evaluation.

Wilson, J. W.; O'Neill, P. J.; Zang, T. A.; Pandolf, J. E.; Tripathi, R. K.; Koontz, Steven L.; Boeder, P.; Reddell, B.; Pankop, C.

2007-01-01

189

Vehicle Shield Optimization and Risk Assessment of Future NEO Missions  

NASA Technical Reports Server (NTRS)

Future human space missions target far destinations such as Near Earth Objects (NEO) or Mars that require extended stay in hostile radiation environments in deep space. The continuous assessment of exploration vehicles is needed to iteratively optimize the designs for shielding protection and calculating the risks associated with such long missions. We use a predictive software capability that calculates the risks to humans inside a spacecraft. The software uses the CAD software Pro/Engineer and Fishbowl tool kit to quantify the radiation shielding properties of the spacecraft geometry by calculating the areal density seen at a certain point, dose point, inside the spacecraft. The shielding results are used by NASA-developed software, BRYNTRN, to quantify the organ doses received in a human body located in the vehicle in a possible solar particle events (SPE) during such prolonged space missions. The organ doses are used to quantify the risks posed on the astronauts' health and life using NASA Space Cancer Model software. An illustration of the shielding optimization and risk calculation on an exploration vehicle design suitable for a NEO mission is provided in this study. The vehicle capsule is made of aluminum shell, airlock with hydrogen-rich carbon composite material end caps. The capsule contains sets of racks that surround a working and living area. A water shelter is provided in the middle of the vehicle to enhance the shielding in case of SPE. The mass distribution is optimized to minimize radiation hotspots and an assessment of the risks associated with a NEO mission is calculated.

Nounu, Hatem, N.; Kim, Myung-Hee; Cucinotta, Francis A.

2011-01-01

190

RADIATION MULTILAYER SHIELD IN THE REACTOR  

Microsoft Academic Search

The design of the reactor radiation shield is an integrated multistep process and consists of interdependent stages. On it's early stages the approximate calculation methods with different accuracy may be applied. We consider here a semi-empirical calculation model of radiation multilayer shield in the reactor having the core and shield configuration-infinite slab. Numerical calculations for three different geometrical configurations (infinite

LE VAN NGOC

2002-01-01

191

Instrumentation concepts and requirements for a space vacuum research facility. [molecular shield for spaceborne experiments  

NASA Technical Reports Server (NTRS)

An earth-orbiting molecular shield that offers a unique opportunity for conducting physics, chemistry, and material processing experiments under a combination of environmental conditions that are not available in terrestrial laboratories is equipped with apparatus for forming a molecular beam from the freestream. Experiments are carried out using a moderate energy, high flux density, high purity atomic oxygen beam in the very low density environment within the molecular shield. As a minimum, the following instruments are required for the molecular shield: (1) a mass spectrometer; (2) a multifunction material analysis instrumentation system; and (3) optical spectrometry equipment. The design is given of a furlable molecular shield that allows deployment and retrieval of the system (including instrumentation and experiments) to be performed without contamination. Interfaces between the molecular shield system and the associated spacecraft are given. An in-flight deployment sequence is discussed that minimizes the spacecraft-induced contamination in the vicinity of the shield. Design approaches toward a precursor molecular shield system are shown.

Norton, H. N.

1979-01-01

192

PLUG STORAGE BUILDING, TRA611, AWAITS SHIELDING SOIL TO BE PLACED ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PLUG STORAGE BUILDING, TRA-611, AWAITS SHIELDING SOIL TO BE PLACED OVER PLUG STORAGE TUBES. WING WALLS WILL SUPPORT EARTH FILL. MTR, PROCESS WATER BUILDING, AND WORKING RESERVOIR IN VIEW BEYOND PLUG STORAGE. CAMERA FACES NORTHEAST. INL NEGATIVE NO. 2949. Unknown Photographer, 7/30/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

193

Earth\\'s Surface  

NSDL National Science Digital Library

You have already learned about the four major parts of Earth\\'s system: atmosphere, hydrosphere, biosphere, and geosphere. Go to the following sites to learn more about rocks and minerals, continental drift, and geologic time. When you finish viewing all the sites, you will participate in a problem-based learning activity, \\"The Case of the Disappearing Dirt.\\" Topographic Maps All About Geology Answer the questions on the handout. Erosion and Weathering Summarize what your learned about erosion and weathering. Examine a landscape formed by erosion Observe the effects of mechanical weathering Plate Tectonics FAQ s About Rocks and Fossils Igneous Rocks Rocks and Minerals Slide Show Rock Cycle Observe an animation of metamorphic rocks forming Continental Drift Mineralogy 4 kids : rockin Internet site : the best place to learn about rocks and minerals Draw a picture of the rock cycle. Coasting Away ...

Mathis, Ms.

2008-01-11

194

Shielding techniques for communication cable - An update  

NASA Astrophysics Data System (ADS)

Techniques of shielding against electronic interference (EI) in the frequency range 1-100 MHz are reviewed. The various sources of EI are discussed, including electrostatic induction; electromagnetic induction; magnetic induction; and electromagnetic pulse (EMP). The effectiveness of different shielding constructions is examined with respect to new FCC regulations for electromagnetic compatibility. Among the shielding constructions examined are: braids; tape shield; and foil designs. The relative transfer impedance of the shielded cable was measured following exposure to EI from the different sources, and the results were compared. The ideal shield for use at frequencies of 1 MHz was a solid copper tube. For frequencies greater than 10 MHz, however, a composite foil/braid was found the most effective shield construction.

Scott, T. R.; Russell, T. R.

195

Design of magnets inside cylindrical superconducting shields  

NASA Technical Reports Server (NTRS)

The design of magnets inside closed, cylindrical, superconducting shields is discussed. The Green function is given for the magnetic vector potential for cylindrically symmetric currents inside such a shield. The magnetic field everywhere inside the shield can be obtained from this function, which includes the effects of the induced shield currents exactly. The field is given for a thin solenoid as an example and the convergence of the series solution for this case is discussed. The shield can significantly reduce the strength and improve the homogeneity of a magnet. The improvement in homogeneity is of particular importance in the design of correction coils. These effects, and the maximum field on the shield, are examined for a typical solenoid. The results given are also useful, although not exact, for long shields with one or two open ends.

Rigby, K. W.

1988-01-01

196

Light shield for solar concentrators  

DOEpatents

A solar receiver unit including a housing defining a recess, a cell assembly received in the recess, the cell assembly including a solar cell, and a light shield received in the recess and including a body and at least two tabs, the body defining a window therein, the tabs extending outward from the body and being engaged with the recess, wherein the window is aligned with the solar cell.

Plesniak, Adam P.; Martins, Guy L.

2014-08-26

197

Photonic Bandgap (PBG) Shielding Technology  

NASA Technical Reports Server (NTRS)

Photonic Bandgap (PBG) shielding technology is a new approach to designing electromagnetic shielding materials for mitigating Electromagnetic Interference (EM!) with small, light-weight shielding materials. It focuses on ground planes of printed wiring boards (PWBs), rather than on components. Modem PSG materials also are emerging based on planar materials, in place of earlier, bulkier, 3-dimensional PBG structures. Planar PBG designs especially show great promise in mitigating and suppressing EMI and crosstalk for aerospace designs, such as needed for NASA's Constellation Program, for returning humans to the moon and for use by our first human visitors traveling to and from Mars. Photonic Bandgap (PBG) materials are also known as artificial dielectrics, meta-materials, and photonic crystals. General PBG materials are fundamentally periodic slow-wave structures in I, 2, or 3 dimensions. By adjusting the choice of structure periodicities in terms of size and recurring structure spacings, multiple scatterings of surface waves can be created that act as a forbidden energy gap (i.e., a range of frequencies) over which nominally-conductive metallic conductors cease to be a conductor and become dielectrics. Equivalently, PBG materials can be regarded as giving rise to forbidden energy gaps in metals without chemical doping, analogous to electron bandgap properties that previously gave rise to the modem semiconductor industry 60 years ago. Electromagnetic waves cannot propagate over bandgap regions that are created with PBG materials, that is, over frequencies for which a bandgap is artificially created through introducing periodic defects

Bastin, Gary L.

2007-01-01

198

Space vehicle meteoroid shielding design  

NASA Technical Reports Server (NTRS)

Design principles of spaced, multiwall meteoroid protection are investigated in the light of experimental data generated during the Apollo Program. The outer wall or shield is shown to be the most important element in the meteoroid-spacecraft interaction. The condition of the debris is primarily a function of the shock pressure, the melting points of the meteoroid and the shield, and the length of the meteoroid and thickness of the shield. Spacing between the walls is effective up to approximately 100 times the length of the meteoroid. The required thickness of the second wall is shown to be proportional to the meteoroid mass, velocity, and density, and to the spacing between the walls, taken with exponents dependent upon the condition of the debris. The effects of placing additional elements (insulation or honeycomb cells) between the two walls are discussed, and the efficiency of various protective configurations is presented. An analysis of the meteoroid protection proposed for the Comet Halley probe is included as an appendix.

Cour-Palais, B. G.

1979-01-01

199

Earth's Seasons  

NSDL National Science Digital Library

A computer animation on the reason for the seasons. Voice-over describes the motion of Earth around the sun to show how the sun's light impacts the tilted Earth at different times of the year, causing seasonal changes.

Rochester Museum And Science Center, Strasenburgh P.

200

Earth Planets Space, 62, 333345, 2010 Cosmic ray and solar energetic particle flux in paleomagnetospheres  

E-print Network

Earth Planets Space, 62, 333­345, 2010 Cosmic ray and solar energetic particle flux of the shield prohibiting energetic particles of solar and cosmic origin directly hitting the Earth surface particles. 1. Introduction Planet Earth possesses a global magnetic field since at least 3.2 billion years

Steinhoff, Heinz-Jürgen

201

Flexible Shields for Protecting Spacecraft Against Debris  

NASA Technical Reports Server (NTRS)

A report presents the concept of Flexshield a class of versatile, lightweight, flexible shields for protecting spacecraft against impacts by small meteors and orbiting debris. The Flexshield concept incorporates elements of, but goes beyond, prior spacecraft-shielding concepts, including those of Whipple shields and, more recently, multi-shock shields and multi-shock blankets. A shield of the Flexshield type includes multiple outer layers (called bumpers in the art) made, variously, of advanced ceramic and/or polymeric fibers spaced apart from each other by a lightweight foam. As in prior such shields, the bumpers serve to shock an impinging hypervelocity particle, causing it to disintegrate vaporize, and spread out over a larger area so that it can be stopped by an innermost layer (back sheet). The flexibility of the fabric layers and compressibility of the foam make it possible to compress and fold the shield for transport, then deploy the shield for use. The shield can be attached to a spacecraft by use of snaps, hook-and-pile patches, or other devices. The shield can also contain multilayer insulation material, so that it provides some thermal protection in addition to mechanical protection.

Christiansen, Eric L.; Crews, Jeanne Lee

2004-01-01

202

The Feasibility of Multipole Electrostatic Radiation Shielding  

NASA Technical Reports Server (NTRS)

Although passive shielding appears to be the only workable solution for galactic cosmic radiation (GCR), active shielding may play an important augmenting role to control the dose from solar particle events (SPEs). It has been noted that, to meet the guidelines of NCRP Report No. 98 through the six SPEs of 1989, a crew member would need roughly double the passive shielding that is necessary to control the GCR dose . This would dramatically increase spacecraft mass, and so it has been proposed that a small but more heavily shielded storm shelter may be used to protect the crew during SPEs. Since a gradual SPE may last 5 or more days, staying in a storm shelter may be psychologically and physiologically distressing to the crew. Storm shelters do not provide shielding for the spacecraft itself against the SPE radiation, and radiation damage to critical electronics may result in loss of mission and life. Single-event effects during the radiation storm may require quick crew response to maintain the integrity of the spacecraft, and confining the crew to a storm shelter prohibits their attending to the spacecraft at the precise time when that attention is needed the most. Active shielding cannot protect against GCR because the particle energies are too high. Although lower energy particles are easier to stop in a passive shield, such shielding is more satisfactory against GCR than against SPE radiation because of the tremendous difference in their initial fluences. Even a small fraction of the SPE fluence penetrating the passive shielding may result in an unacceptably high dose. Active shielding is more effective than passive shielding against SPE radiation because it offers 100% shielding effectiveness up to the cutoff energy, and significant shielding effectiveness beyond the cutoff as well.

Metzger, Philip T.; Lane, John E.; Youngquist, Robert C.

2004-01-01

203

Exploratory Environmental Tests of Several Heat Shields  

NASA Technical Reports Server (NTRS)

Exploratory tests have been conducted with several conceptual radiative heat shields of composite construction. Measured transient temperature distributions were obtained for a graphite heat shield without insulation and with three types of insulating materials, and for a metal multipost heat shield, at surface temperatures of approximately 2,000 F and 1,450 F, respectively, by use of a radiant-heat facility. The graphite configurations suffered loss of surface material under repeated irradiation. Temperature distribution calculated for the metal heat shield by a numerical procedure was in good agreement with measured data. Environmental survival tests of the graphite heat shield without insulation, an insulated multipost heat shield, and a stainless-steel-tile heat shield were made at temperatures of 2,000 F and dynamic pressures of approximately 6,000 lb/sq ft, provided by an ethylene-heated jet operating at a Mach number of 2.0 and sea-level conditions. The graphite heat shield survived the simulated aerodynamic heating and pressure loading. A problem area exists in the design and materials for heat-resistant fasteners between the graphite shield and the base structure. The insulated multipost heat shield was found to be superior to the stainless-steel-tile heat shield in retarding heat flow. Over-lapped face-plate joints and surface smoothness of the insulated multi- post heat shield were not adversely affected by the test environment. The graphite heat shield without insulation survived tests made in the acoustic environment of a large air jet. This acoustic environment is random in frequency and has an overall noise level of 160 decibels.

Goodman, George P.; Betts, John, Jr.

1961-01-01

204

Edible Earth  

NSDL National Science Digital Library

In this activity, learners make a model of the solid Earth's layers that's good enough to eat! Learners use tasty foodstuffs to simulate Earth's inner core, outer core, mantle, and crust. The recipe includes ingredients for one edible Earth, but can be doubled or tripled to accommodate groups of learners. This activity requires adult supervision.

American Museum of Natural History

2011-08-20

205

Earth Flow  

NSDL National Science Digital Library

This Flash animation with accompanying audio exhibits the different stages involved in the formation of an earth flow. A step-like scarp forms along with a flowage zone at the toe of the earth flow. The sequence concludes with the stabilization of the earth flow with vegetation. Expect long loading times.

Wiley

206

Planet Earth  

NSDL National Science Digital Library

For those interested in a global view of the weather, Planet Earth is a "real-time 3-D model of the Earth with continuously updating night shadows and clouds." Cloud images are provided by the University of Wisconsin-Madison Space Science and Engineering Center. Planet Earth is shareware with a fee of $29.95.

207

Earth Calendar  

NSDL National Science Digital Library

This handout lists major events in Earth history with approximate ages (in millions of years before present). The calendar date is determined by setting midnight, January 1, to correspond with the formation of the Earth, and setting the following midnight, December 31, to correspond to the present. Thus, the entire history of the Earth is displayed as a single calendar year.

Barker, Jeffrey

208

Snowball Earth  

NSDL National Science Digital Library

Audio program from the University of Wisconsin's Earthwatch Radio discusses the notion of the entire planet covered with ice. Doug Macdougall is an earth scientist at the University of California-San Diego and author of a new book called "Frozen Earth." He says the planet-wide freeze is known as "Snowball Earth."

209

Terrestrial Background Reduction in RPM Systems by Direct Internal Shielding  

SciTech Connect

Gamma-ray detection systems that are close to the earth or other sources of background radiation often require shielding, especially when trying to detect a relatively weak source. One particular case of interest that we address in this paper is that encountered by the Radiation Portal Monitors (RPMs) systems placed at border-crossing Ports of Entry (POE). These RPM systems are used to screen for illicit radiological materials, and they are often placed in situations where terrestrial background is large. In such environments, it is desirable to consider simple physical modifications that could be implemented to reduce the effects from background radiation without affecting the flow of traffic and the normal operation of the portal. Simple modifications include adding additional shielding to the environment, either inside or outside the apparatus. Previous work [2] has shown the utility of some of these shielding configurations for increasing the Signal to Noise Ratio (SNR) of gross-counting RPMs. Because the total cost for purchasing and installing RPM systems can be quite expensive, in the range of hundreds of thousands of dollars for each cargo-screening installation, these shielding variations may offer increases in detection capability for relatively small cost. Several modifications are considered here in regard to their real-world applicability, and are meant to give a general idea of the effectiveness of the schemes used to reduce background for both gross-counting and spectroscopic detectors. These scenarios are modeled via the Monte-Carlo N-Particle (MCNP) code package [1] for ease of altering shielding configurations, as well as enacting unusual scenarios prior to prototyping in the field. The objective of this paper is to provide results representative of real modifications that could enhance the sensitivity of this, as well as the next generation of radiation detectors. The models used in this work were designed to provide the most general results for an RPM. These results are therefore presented as general guidance on what shielding configurations will be the most valuable for a generalized RPM, considered in light of their economic and geometric possibility in the real world.

Robinson, Sean M.; Ashbaker, Eric D.; Schweppe, John E.

2008-11-19

210

Radiation Exposure Analyses Supporting the Development of Solar Particle Event Shielding Technologies  

NASA Technical Reports Server (NTRS)

NASA has plans for long duration missions beyond low Earth orbit (LEO). Outside of LEO, large solar particle events (SPEs), which occur sporadically, can deliver a very large dose in a short amount of time. The relatively low proton energies make SPE shielding practical, and the possibility of the occurrence of a large event drives the need for SPE shielding for all deep space missions. The Advanced Exploration Systems (AES) RadWorks Storm Shelter Team was charged with developing minimal mass SPE storm shelter concepts for missions beyond LEO. The concepts developed included "wearable" shields, shelters that could be deployed at the onset of an event, and augmentations to the crew quarters. The radiation transport codes, human body models, and vehicle geometry tools contained in the On-Line Tool for the Assessment of Radiation In Space (OLTARIS) were used to evaluate the protection provided by each concept within a realistic space habitat and provide the concept designers with shield thickness requirements. Several different SPE models were utilized to examine the dependence of the shield requirements on the event spectrum. This paper describes the radiation analysis methods and the results of these analyses for several of the shielding concepts.

Walker, Steven A.; Clowdsley, Martha S.; Abston, H. Lee; Simon, Hatthew A.; Gallegos, Adam M.

2013-01-01

211

Dynamic rotating-shield brachytherapy  

SciTech Connect

Purpose: To present dynamic rotating shield brachytherapy (D-RSBT), a novel form of high-dose-rate brachytherapy (HDR-BT) with electronic brachytherapy source, where the radiation shield is capable of changing emission angles during the radiation delivery process.Methods: A D-RSBT system uses two layers of independently rotating tungsten alloy shields, each with a 180° azimuthal emission angle. The D-RSBT planning is separated into two stages: anchor plan optimization and optimal sequencing. In the anchor plan optimization, anchor plans are generated by maximizing the D{sub 90} for the high-risk clinical-tumor-volume (HR-CTV) assuming a fixed azimuthal emission angle of 11.25°. In the optimal sequencing, treatment plans that most closely approximate the anchor plans under the delivery-time constraint will be efficiently computed. Treatment plans for five cervical cancer patients were generated for D-RSBT, single-shield RSBT (S-RSBT), and {sup 192}Ir-based intracavitary brachytherapy with supplementary interstitial brachytherapy (IS + ICBT) assuming five treatment fractions. External beam radiotherapy doses of 45 Gy in 25 fractions of 1.8 Gy each were accounted for. The high-risk clinical target volume (HR-CTV) doses were escalated such that the D{sub 2cc} of the rectum, sigmoid colon, or bladder reached its tolerance equivalent dose in 2 Gy fractions (EQD2 with ?/?= 3 Gy) of 75 Gy, 75 Gy, or 90 Gy, respectively.Results: For the patients considered, IS + ICBT had an average total dwell time of 5.7 minutes/fraction (min/fx) assuming a 10 Ci{sup 192}Ir source, and the average HR-CTV D{sub 90} was 78.9 Gy. In order to match the HR-CTV D{sub 90} of IS + ICBT, D-RSBT required an average of 10.1 min/fx more delivery time, and S-RSBT required 6.7 min/fx more. If an additional 20 min/fx of delivery time is allowed beyond that of the IS + ICBT case, D-RSBT and S-RSBT increased the HR-CTV D{sub 90} above IS + ICBT by an average of 16.3 Gy and 9.1 Gy, respectively.Conclusions: For cervical cancer patients, D-RSBT can boost HR-CTV D{sub 90} over IS + ICBT and S-RSBT without violating the tolerance doses to the bladder, rectum, or sigmoid. The D{sub 90} improvements from D-RSBT depend on the patient, the delivery time budget, and the applicator structure.

Liu, Yunlong [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 (United States)] [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 (United States); Flynn, Ryan T.; Kim, Yusung [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)] [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Yang, Wenjun [Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin 53705 (United States)] [Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin 53705 (United States); Wu, Xiaodong [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 and Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)] [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 and Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)

2013-12-15

212

Dynamic rotating-shield brachytherapy  

PubMed Central

Purpose: To present dynamic rotating shield brachytherapy (D-RSBT), a novel form of high-dose-rate brachytherapy (HDR-BT) with electronic brachytherapy source, where the radiation shield is capable of changing emission angles during the radiation delivery process. Methods: A D-RSBT system uses two layers of independently rotating tungsten alloy shields, each with a 180° azimuthal emission angle. The D-RSBT planning is separated into two stages: anchor plan optimization and optimal sequencing. In the anchor plan optimization, anchor plans are generated by maximizing the D90 for the high-risk clinical-tumor-volume (HR-CTV) assuming a fixed azimuthal emission angle of 11.25°. In the optimal sequencing, treatment plans that most closely approximate the anchor plans under the delivery-time constraint will be efficiently computed. Treatment plans for five cervical cancer patients were generated for D-RSBT, single-shield RSBT (S-RSBT), and 192Ir-based intracavitary brachytherapy with supplementary interstitial brachytherapy (IS + ICBT) assuming five treatment fractions. External beam radiotherapy doses of 45 Gy in 25 fractions of 1.8 Gy each were accounted for. The high-risk clinical target volume (HR-CTV) doses were escalated such that the D2cc of the rectum, sigmoid colon, or bladder reached its tolerance equivalent dose in 2 Gy fractions (EQD2 with ?/? = 3 Gy) of 75 Gy, 75 Gy, or 90 Gy, respectively. Results: For the patients considered, IS + ICBT had an average total dwell time of 5.7 minutes/fraction (min/fx) assuming a 10 Ci192Ir source, and the average HR-CTV D90 was 78.9 Gy. In order to match the HR-CTV D90 of IS + ICBT, D-RSBT required an average of 10.1 min/fx more delivery time, and S-RSBT required 6.7 min/fx more. If an additional 20 min/fx of delivery time is allowed beyond that of the IS + ICBT case, D-RSBT and S-RSBT increased the HR-CTV D90 above IS + ICBT by an average of 16.3 Gy and 9.1 Gy, respectively. Conclusions: For cervical cancer patients, D-RSBT can boost HR-CTV D90 over IS + ICBT and S-RSBT without violating the tolerance doses to the bladder, rectum, or sigmoid. The D90 improvements from D-RSBT depend on the patient, the delivery time budget, and the applicator structure. PMID:24320489

Liu, Yunlong; Flynn, Ryan T.; Kim, Yusung; Yang, Wenjun; Wu, Xiaodong

2013-01-01

213

Tests of shielding effectiveness of Kevlar and Nextel onboard the International Space Station and the Foton-M3 capsule.  

PubMed

Radiation assessment and protection in space is the first step in planning future missions to the Moon and Mars, where mission and number of space travelers will increase and the protection of the geomagnetic shielding against the cosmic radiation will be absent. In this framework, the shielding effectiveness of two flexible materials, Kevlar and Nextel, were tested, which are largely used in the construction of spacecrafts. Accelerator-based tests clearly demonstrated that Kevlar is an excellent shield for heavy ions, close to polyethylene, whereas Nextel shows poor shielding characteristics. Measurements on flight performed onboard of the International Space Station and of the Foton-M3 capsule have been carried out with special attention to the neutron component; shielded and unshielded detectors (thermoluminescence dosemeters, bubble detectors) were exposed to a real radiation environment to test the shielding properties of the materials under study. The results indicate no significant effects of shielding, suggesting that thin shields in low-Earth Orbit have little effect on absorbed dose. PMID:20364264

Pugliese, M; Bengin, V; Casolino, M; Roca, V; Zanini, A; Durante, M

2010-08-01

214

From plume head to continental lithosphere in the Arabian-Nubian shield  

NASA Astrophysics Data System (ADS)

The lithosphere of the Arabian-Nubian shield was mainly formed during an interval of about 150 million years near the end of the Proterozoic aeon. The events recorded in the rocks of the shield indicate that an oceanic plateau, formed by the head of an upwelling mantle plume, was later overprinted with continent-like characteristics by plate convergence and its associated magmatism. Similar sequences of events are seen in the geological record from Archaean to recent times, suggesting that the transformation from plume head to continental lithosphere has been an important component of continent generation throughout Earth history.

Stein, Mordechai; Goldstein, Steven L.

1996-08-01

215

Ballistic limit equations for spacecraft shielding  

Microsoft Academic Search

This paper provides equations describing the ballistic performance capability of meteoroid\\/orbital debris (M\\/OD) shield systems employed on the International Space Station (ISS). Hypervelocity impact (HVI) tests and analysis were used in developing the semi-empirical ballistic limit equations (BLE). A description of each type of shield system, HVI tests and analysis performed to assess shield performance, and ballistic limit equations that

Eric L. Christiansen; Justin H. Kerr

2001-01-01

216

Hot Cell Window Shielding Analysis Using MCNP  

SciTech Connect

The Idaho National Laboratory Materials and Fuels Complex nuclear facilities are undergoing a documented safety analysis upgrade. In conjunction with the upgrade effort, shielding analysis of the Fuel Conditioning Facility (FCF) hot cell windows has been conducted. This paper describes the shielding analysis methodology. Each 4-ft thick window uses nine glass slabs, an oil film between the slabs, numerous steel plates, and packed lead wool. Operations in the hot cell center on used nuclear fuel (UNF) processing. Prior to the shielding analysis, shield testing with a gamma ray source was conducted, and the windows were found to be very effective gamma shields. Despite these results, because the glass contained significant amounts of lead and little neutron absorbing material, some doubt lingered regarding the effectiveness of the windows in neutron shielding situations, such as during an accidental criticality. MCNP was selected as an analysis tool because it could model complicated geometry, and it could track gamma and neutron radiation. A bounding criticality source was developed based on the composition of the UNF. Additionally, a bounding gamma source was developed based on the fission product content of the UNF. Modeling the windows required field inspections and detailed examination of drawings and material specifications. Consistent with the shield testing results, MCNP results demonstrated that the shielding was very effective with respect to gamma radiation, and in addition, the analysis demonstrated that the shielding was also very effective during an accidental criticality.

Chad L. Pope; Wade W. Scates; J. Todd Taylor

2009-05-01

217

The ORNL-SNAP shielding program  

NASA Technical Reports Server (NTRS)

The effort in the ORNL-SNAP shielding program is directed toward the development and verification of computer codes using numerical solutions to the transport equation for the design of optimized radiation shields for SNAP power systems. A brief discussion is given for the major areas of the SNAP shielding program, which are cross-section development, transport code development, and integral experiments. Detailed results are presented for the integral experiments utilizing the TSF-SNAP reactor. Calculated results are compared with experiments for neutron and gamma-ray spectra from the bare reactor and as transmitted through slab shields.

Mynatt, F. R.; Clifford, C. E.; Muckenthaler, F. J.; Gritzner, M. L.

1972-01-01

218

Development of Flexible Neutron-Shielding Resin as an Additional Shielding Material  

Microsoft Academic Search

A soft-type neutron-shielding resin has been developed by improving an existing hard-type neutronshielding material using the epoxy-based resin as an additional shielding material. A flexible heat-resistant neutron-shielding material has been developed, which consists of a new polymer-based resin with boron. The neutron shielding performance of the developed flexible heat-resistant resin with the Cf neutron source is almost the same as

Atsuhiko M. SUKEGAWA; Yoshimasa ANAYAMA; Seiki OHNISHI; Shinji SAKURAI; Atsushi KAMINAGA; Koichi OKUNO

2011-01-01

219

Radiation environment and shielding for early manned Mars missions  

NASA Technical Reports Server (NTRS)

The problem of shielding a crew during early manned Mars missions is discussed. Requirements for shielding are presented in the context of current astronaut exposure limits, natural ionizing radiation sources, and shielding inherent in a particular Mars vehicle configuration. An estimated range for shielding weight is presented based on the worst solar flare dose, mission duration, and inherent vehicle shielding.

Hall, Stephen B.; Mccann, Michael E.

1986-01-01

220

High Density Perpendicular Recording With Wrap-Around Shielded Writer  

Microsoft Academic Search

Wrap-around shielded writers combining both trailing shield and side shield have been studied both by modeling and by experiments. WAS design is demonstrated to have superior performance over its predecessor trailing shielded writer in perpendicular magnetic recording systems. While maintaining the down-track performance, the side shield significantly reduces the side fringing field, thus enabling high track densities. In this paper,

Daniel Z. Bai; Yan Wu; Moris Dovek; Yue Liu; Xiaofeng Zhang; Kowang Liu; Kenichi Takano; Yuchen Zhou

2010-01-01

221

Dynamic Earth  

NSDL National Science Digital Library

Dynamic Earth consists of four sections and an assessment. Each section explores one aspect of the earth's structure and the movement of its tectonic plates. Simply follow the instructions on the screen to learn about the layers that make up the earth; how the continents arrived at their current locations; the constant movement of the tectonic plates; and the volcanoes, earthquakes, and other events that result from the movements of the plates. Students will view animations, read explanations, and use their mouse to drag and drop the earth's continents in their correct places, highlight features on a map, and cause earth's tectonic plates to move. At various points, students will check their knowledge by taking a quick quiz or playing a game to see how much they have learned about the Dynamic Earth. Students should read section introductions carefully, as they give a basic overview of concepts, and use the Glossary to look up definitions to unfamiliar terms.

Ashlinn Quinn

2007-01-01

222

Celebrate Earth  

NSDL National Science Digital Library

The Earth is truly something to celebrate! Click on the links below and have some fun! Click on the link to send you to a fun website created just for kids like you! Now go celebrate the earth! Kids for Saving Earth Enjoy these other activities as well! Go recycling! A is for Air Discover what all of the letters of the alphabet can stand for! video Get on ...

Mrs. Rokes

2009-04-23

223

Earth Force  

NSDL National Science Digital Library

"Earth Force engages young people as active citizens who improve the environment and their communities now and in the future." Educators can learn about Earth Force's three programs: Community Action and Problem solving (CAPS), the Global Rivers Environmental Education Network (GREEN), and Earth Force After School. Users can discover students' many accomplishments such as creating reusable fabric grocery bags, recycling cell phones and ink cartridges to earn money, and cleaning up litter. The Tools for Teachers section offers evaluation results, a quality rubric, and a description of the six-step Earth Force community action and problem-solving process.

224

The Radiation Shielding Competition Sponsored by  

E-print Network

: A radiation shield, simply put, is anything that blocks radiation from an intended target. It can doThe Radiation Shielding Competition Sponsored by: The American Nuclear Society (MNS) Introduction this by absorbing the energy from the radiation. As unstable elements decay, they typically release some sort

Wang, Xiaorui "Ray"

225

International Space Station Radiation Shielding Model Development  

Microsoft Academic Search

The projected radiation levels within the International Space Station (ISS) have been criticized by the Aerospace Safety Advisory Panel in their report to the NASA Administrator. Methods for optimal reconfig- uration and augmentation of the ISS shielding are now being developed. The initial steps are to develop reconfigurable and realistic radiation shield models of the ISS modules, develop computational procedures

G. D. Qualls; J. W. Wilson; C. Sandridge; F. A. Cucinotta; J. E. Nealy; J. H. Heinbockel; C. P. Hugger; J. Verhage; B. M. Anderson; W. Atwell

226

Deep Space Mission Radiation Shielding Optimization  

Microsoft Academic Search

Providing protection against the hazards of space radiation is a major challenge to the exploration and development of space. The great cost of added radiation shielding is a potential limiting factor in deep space missions. In the present report, we present methods for optimized shield design over multi-segmented missions involving multiple work and living areas in the transport and duty

R. K. Tripathi; J. W. Wilson; F. A. Cucinotta; M. S. Clowdsley; M.-H. Y. Kim

2001-01-01

227

Thermal radiation shields for radiant coolers  

Microsoft Academic Search

Thermal radiation shields in the form of low-emissivity surfaces spaced on low-conductance supports can be used to advantage as a replacement for multilayer insulation in radiant coolers. A view factor between adjacent shields of less than unity increases the insulation factor when the surfaces terminate with an external view. An analytical model that accounts for unequal areas as well as

R. V. Annable

1976-01-01

228

Beam Plug for Radiation Shielding Penetrations  

Microsoft Academic Search

A beam line plug has been designed to fill the cylindrical hole formed by beam lines which pass through radiation shielding walls. The plug consists of multiple steel discs held together along their cylindrical axis by a steel cable forming a flexible snake-like structure. Other disc materials including laminates may be used to solve a variety of radiation shielding problems.

M. A. Manni; K. F. Minati

1971-01-01

229

Plastron Shielding Technologies Liquid Repellent Surface Coating  

E-print Network

Plastron Shielding Technologies Liquid Repellent Surface Coating Plastron Shielding Technologies provides coatings that cause treated surfaces to repel dust, dirt, and liquids, making them easy to clean com- pared to existing products. Technology Most current technologies in the surface-coating arena

Jawitz, James W.

230

SHLDUTIL: A Code for Useful Shielding Data  

E-print Network

of our texts (1) Radiation Shielding, ISBN 0-89448-456-7, American Nuclear Society, La Grange Park, IL for Radiation Shielding and "RA" for Radiological Assessment. The primary sources for the data bases used can albedos 7 neutron & sec. gamma albedos 8 proton/electron ranges 9 fission product decay power 10 th

Shultis, J. Kenneth

231

Current status of methods for shielding analysis  

SciTech Connect

Current methods used in shielding analysis and recent improvements in those methods are discussed. The status of methods development is discussed based on needs cited at the 1977 International Conference on Reactor Shielding. Additional areas where methods development is needed are discussed.

Engle, W.W.

1980-01-01

232

Studies on the neutron field behind shielding of proton accelerators Part I: Concrete shielding  

NASA Astrophysics Data System (ADS)

Energy- and angular distributions of neutrons behind concrete side shielding of proton accelerators were calculated. Simple arguments are given to understand the characteristic shape of the neutron spectrum. Calculations were repeated to receive data for simple shielding estimations. The dose equivalent attenuation coefficient of concrete for monoenergetic neutrons with energies between 1 and 400 MeV were determined and compared with the coefficient for neutrons leaving an accelerator shield at angles around 90°. Data for shielding gaps in accelerator shielding walls are given as an application. The calculations were performed by using the Monte Carlo codes FLUKA92 and MORSE.

Dinter, H.; Tesch, K.; Dworak, D.

1996-01-01

233

The Stopping Power of Asteroidal Materials as High-Energy Charged Particle Shielding  

NASA Astrophysics Data System (ADS)

Extended human missions in deep space face a challenging radiation environment from high-energy galactic cosmic rays and solar energetic particles generated by solar flares and related coronal mass ejections. Shielding to attenuate these high-energy particles will require significant mass and volume, and would be extremely expensive launch from the surface of the earth. One possible solution could be the use of asteroidal resources as shielding for these high-energy particles. The effectiveness of shielding material for moderately relativistic charged particles is a function of the mean rate of energy loss, primarily to ionization and atomic excitation and is termed stopping power. In general, low atomic number elements are more effective per unit volume. We have calculated the stopping power for the average compositions of all major meteorite groups and will compare these data with typical spacecraft materials.

Pohl, Leos; Johnson, Daniel; Britt, Daniel

2014-11-01

234

Regolith-Derived Heat Shield for Planetary Body Entry and Descent System with In Situ Fabrication  

NASA Technical Reports Server (NTRS)

In this paper we will discuss a new mass-efficient and innovative way of protecting high-mass spacecraft during planetary Entry, Descent & Landing (EDL). Heat shields fabricated in situ can provide a thermal-protection system (TPS) for spacecraft that routinely enter a planetary atmosphere. By fabricating the heat shield with space resources from regolith materials available on moons and asteroids, it is possible to avoid launching the heat-shield mass from Earth. Three regolith processing and manufacturing methods will be discussed: 1) oxygen & metal extraction ISRU processes produce glassy melts enriched in alumina and titania, processed to obtain variable density, high melting point and heat-resistance; 2) compression and sintering of the regolith yield low density materials; 3) in-situ derived high-temperature polymers are created to bind regolith particles together, with a lower energy budget.

Hogue, Michael D.; Mueller, Robert P.; Rasky, Daniel J.; Hintze, Paul E.; Sibille, Laurent

2011-01-01

235

Regolith-Derived Heat Shield for Planetary Body Entry and Descent System with In Situ Fabrication  

NASA Technical Reports Server (NTRS)

In this paper we will discuss a new mass-efficient and innovative way of protecting high-mass spacecraft during planetary Entry, Descent & Landing (EDL). Heat shields fabricated in situ can provide a thermal-protection system (TPS) for spacecraft that routinely enter a planetary atmosphere. By fabricating the heat shield with space resources from regolith materials available on moons and asteroids, it is possible to avoid launching the heat-shield mass from Earth. Two regolith processing and manufacturing methods will be discussed: 1) Compression and sintering of the regolith to yield low density materials; 2) Formulations of a High-temperature silicone RTV (Room Temperature Vulcanizing) compound are used to bind regolith particles together. The overall positive results of torch flame impingement tests and plasma arc jet testing on the resulting samples will also be discussed.

Hogue, Michael D.; Mueller, Robert P.; Rasky, Daniel; Hintze, Paul; Sibille, Laurent

2012-01-01

236

Spacesuit Radiation Shield Design Methods  

NASA Technical Reports Server (NTRS)

Meeting radiation protection requirements during EVA is predominantly an operational issue with some potential considerations for temporary shelter. The issue of spacesuit shielding is mainly guided by the potential of accidental exposure when operational and temporary shelter considerations fail to maintain exposures within operational limits. In this case, very high exposure levels are possible which could result in observable health effects and even be life threatening. Under these assumptions, potential spacesuit radiation exposures have been studied using known historical solar particle events to gain insight on the usefulness of modification of spacesuit design in which the control of skin exposure is a critical design issue and reduction of blood forming organ exposure is desirable. Transition to a new spacesuit design including soft upper-torso and reconfigured life support hardware gives an opportunity to optimize the next generation spacesuit for reduced potential health effects during an accidental exposure.

Wilson, John W.; Anderson, Brooke M.; Cucinotta, Francis A.; Ware, J.; Zeitlin, Cary J.

2006-01-01

237

Shielding calculations at dismantled synchrocyclotron  

SciTech Connect

The Space Radiation Effects Laboratory located in Newport News, Virginia, was operated by the College of William and Mary for the National Aeronautics and Space Administration. A synchrocyclotron which was formerly in operation in this building was removed in 1980. At several locations, the scattered radiation caused an induced radioactivity within the walls of the cyclotron room. A radiological survey has been performed to determine the amount of residual radioactivity on the walls. Calculations were performed to determine the thickness of the concrete walls and floor for shielding the residual radiation in the cyclotron room. Recommendations are made to minimize exposures from the residual radioactivity on the walls and floor of the cyclotron room to potential occupants working in the building. 19 refs., 1 fig., 2 tabs.

Yalcintas, M.G.

1987-01-01

238

Foam Core Shielding for Spacecraft  

NASA Technical Reports Server (NTRS)

A foam core shield (FCS) system is now being developed to supplant multilayer insulation (MLI) systems heretofore installed on spacecraft for thermal management and protection against meteoroid impacts. A typical FCS system consists of a core sandwiched between a face sheet and a back sheet. The core can consist of any of a variety of low-to-medium-density polymeric or inorganic foams chosen to satisfy application-specific requirements regarding heat transfer and temperature. The face sheet serves to shock and thereby shatter incident meteoroids, and is coated on its outer surface to optimize its absorptance and emittance for regulation of temperature. The back sheet can be dimpled to minimize undesired thermal contact with the underlying spacecraft component and can be metallized on the surface facing the component to optimize its absorptance and emittance. The FCS systems can perform better than do MLI systems, at lower mass and lower cost and with greater volumetric efficiency.

Adams, Marc

2007-01-01

239

GFR Sub-Assembly Shielding Design Studies  

SciTech Connect

This report presents the methodology and results for a preliminary study for Gas-Cooled Fast Reactor (GFR) subassembly fast neutron shielding configurations. The purpose of the shielding in the subassembly is to protect reactor components from fast (E>0.1 MeV) neutrons. The subassembly is modeled in MCNP version 5 release 1.30. Parametric studies were performed varying the thickness of the shielding and calculating the fast neutron flux at the vessel head and the core grid plate. This data was used to determine the minimum thickness needed to protect the vessel head and the core grid plate. These thicknesses were used to analyze different shielding configurations incorporating coolant passages and also to estimate the neutron and photon energy deposition in the shielding material.

J. R. Parry

2006-01-01

240

Repository Waste Package Transporter Shielding Weight Optimization  

SciTech Connect

The Yucca Mountain repository requires the use of a waste package (WP) transporter to transport a WP from a process facility on the surface to the subsurface for underground emplacement. The transporter is a part of the waste emplacement transport systems, which includes a primary locomotive at the front end and a secondary locomotive at the rear end. The overall system with a WP on board weights over 350 metric tons (MT). With the shielding mass constituting approximately one-third of the total system weight, shielding optimization for minimal weight will benefit the overall transport system with reduced axle requirements and improved maneuverability. With a high contact dose rate on the WP external surface and minimal personnel shielding afforded by the WP, the transporter provides radiation shielding to workers during waste emplacement and retrieval operations. This paper presents the design approach and optimization method used in achieving a shielding configuration with minimal weight.

C.E. Sanders; Shiaw-Der Su

2005-02-02

241

Earth Day  

NSDL National Science Digital Library

On April 22, 2005, people around the world will celebrate the 35th anniversary of Earth Day. This Topic in Depth focuses on the past and present of this significant day. From the Wisconsin Historical Society, the first two sites contain historical documents pertaining to Earth Day. The first (1) document features a May 1970 issue of The Gaylord Nelson Newsletter reporting on the first Earth Day. The second (2) document is a speech by Nelson entitled "An Environmental Agenda for the 70's." Housed in the archives of the US Environmental Protection Agency (EPA) website, the next two sites also contain historical documents. The first (3) site contains an article written by Nelson for the EPA Journal in April of 1980, entitled "Earth Day '70: What It Meant." The second (4) site contains an article written by John C. Whitaker (former Interior undersecretary in the Nixon administration) for the EPA Journal in the summer of 1998. The article is entitled "Earth Day Recollections: What It Was Like When the Movement Took Off." The (5) Earth Day Network (first mentioned in the April 4, 2003, Scout Report for Life Sciences) works "to broaden the environmental movement worldwide and to educate and mobilize people, governments, and corporations to take responsibility for a clean and healthy environment." In addition to information sections about Ongoing Programs, Current Campaigns, and News, the Earth Day Network website contains Earth Day 2005 Materials for organizers. From EarthDay.gov, Take Action In Your Classroom (6) offers links to a variety of environmental education resources. The next website, from the U.S. Army Environmental Center, presents (7) Army Earth Day; and links to information about the Army's environmental activities. The final (8) site is an Earth Day-inspired educational website (first reported on in the April 14, 1999 Scout Report for Science & Engineering) from the Wilderness Society. The site offers a collection of environmental education resources for teachers and students. [NL

242

LET spectra measurements on LDEF: variations with shielding and location  

NASA Technical Reports Server (NTRS)

LET spectra measurements made with passive plastic nuclear track detectors (PNTDs) were found to depend on detector orientation, shielding and experiment location. LET spectra were measured at several locations on LDEF as part of the P0006 LETSME experiment (Benton and Parnell, 1984), the P0004 Seeds in Space experiment (Parks and Alston, 1984), the A00l5 Free Flyer Biostacks and the M0004 Fiber Optics Data Link experiment (Taylor, 1984). Locations included the east, west and Earth sides of the LDEF satellite. The LET spectra measured with PNTDs deviated significantly from calculations, especially for high LET particles (LET infinity H2O > or = 100 keV/micrometer). At high LETs, short-range inelastic secondary particles produced by trapped proton interactions with the nuclei of the detector were found to be the principal contributor to LET spectra. At lower LETs, the spectra appeared to be due to short-range, inelastic and stopping primary protons, with primary GCR particles making a smaller contribution. The dependence of LET spectra on detector orientation and shielding was studied using the four orthogonal stacks in the P0006 experiment. Both measurements of total track density and LET spectra showed a greater number of particles arriving from the direction of space than from Earth. Measurements of LET spectra in CR-39 PNTD on the east (leading) and west (trailing) sides of LDEF showed a higher rate of production at the west side. This was caused by a larger flux of trapped protons on the west side as predicted by the east/west trapped proton anisotropy in the South Atlantic Anomaly (SAA). Track density measured in CR-39 PNTDs increased as a function of shielding depth in the detector stack. A similar measurement made in a thick stack of CR-39 interspersed with layers of Al and exposed to 154 MeV protons at a ground-based accelerator showed a similar result, indicating that a significant fraction of the particle events counted were from secondaries and that the total cross-section for production of proton-induced secondaries increased as the energy of primary protons attenuated. Little change was seen in either total differential or integral LET spectra as a function of shielding depth, indicating that the increase in cross section with decreasing proton energy affected mostly the shorter range secondary components. Similarity in the slopes of LET spectra from ground-based proton exposures and the A00l5 LET spectra showed that modeling of a monoenergetic proton beam transported through a 1-D geometry was a useful first step in modeling the production of secondary particles by trapped protons in the SAA.

Benton, E. V.; Frank, A. L.; Csige, I.; Frigo, L. A.; Benton, E. R.

1996-01-01

243

LET spectra measurements on LDEF: variations with shielding and location.  

PubMed

LET spectra measurements made with passive plastic nuclear track detectors (PNTDs) were found to depend on detector orientation, shielding and experiment location. LET spectra were measured at several locations on LDEF as part of the P0006 LETSME experiment (Benton and Parnell, 1984), the P0004 Seeds in Space experiment (Parks and Alston, 1984), the A00l5 Free Flyer Biostacks and the M0004 Fiber Optics Data Link experiment (Taylor, 1984). Locations included the east, west and Earth sides of the LDEF satellite. The LET spectra measured with PNTDs deviated significantly from calculations, especially for high LET particles (LET infinity H2O > or = 100 keV/micrometer). At high LETs, short-range inelastic secondary particles produced by trapped proton interactions with the nuclei of the detector were found to be the principal contributor to LET spectra. At lower LETs, the spectra appeared to be due to short-range, inelastic and stopping primary protons, with primary GCR particles making a smaller contribution. The dependence of LET spectra on detector orientation and shielding was studied using the four orthogonal stacks in the P0006 experiment. Both measurements of total track density and LET spectra showed a greater number of particles arriving from the direction of space than from Earth. Measurements of LET spectra in CR-39 PNTD on the east (leading) and west (trailing) sides of LDEF showed a higher rate of production at the west side. This was caused by a larger flux of trapped protons on the west side as predicted by the east/west trapped proton anisotropy in the South Atlantic Anomaly (SAA). Track density measured in CR-39 PNTDs increased as a function of shielding depth in the detector stack. A similar measurement made in a thick stack of CR-39 interspersed with layers of Al and exposed to 154 MeV protons at a ground-based accelerator showed a similar result, indicating that a significant fraction of the particle events counted were from secondaries and that the total cross-section for production of proton-induced secondaries increased as the energy of primary protons attenuated. Little change was seen in either total differential or integral LET spectra as a function of shielding depth, indicating that the increase in cross section with decreasing proton energy affected mostly the shorter range secondary components. Similarity in the slopes of LET spectra from ground-based proton exposures and the A00l5 LET spectra showed that modeling of a monoenergetic proton beam transported through a 1-D geometry was a useful first step in modeling the production of secondary particles by trapped protons in the SAA. PMID:11540510

Benton, E V; Frank, A L; Csige, I; Frigo, L A; Benton, E R

1996-11-01

244

21 CFR 886.4750 - Ophthalmic eye shield.  

Code of Federal Regulations, 2014 CFR

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2014-04-01

245

21 CFR 886.4750 - Ophthalmic eye shield.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Ophthalmic eye shield. 886.4750 Section 886.4750...Surgical Devices § 886.4750 Ophthalmic eye shield. (a) Identification. An ophthalmic eye shield is a device that consists of a...

2011-04-01

246

21 CFR 886.4750 - Ophthalmic eye shield.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Ophthalmic eye shield. 886.4750 Section 886.4750...Surgical Devices § 886.4750 Ophthalmic eye shield. (a) Identification. An ophthalmic eye shield is a device that consists of a...

2013-04-01

247

21 CFR 886.4750 - Ophthalmic eye shield.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Ophthalmic eye shield. 886.4750 Section 886.4750...Surgical Devices § 886.4750 Ophthalmic eye shield. (a) Identification. An ophthalmic eye shield is a device that consists of a...

2012-04-01

248

21 CFR 886.4750 - Ophthalmic eye shield.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Ophthalmic eye shield. 886.4750 Section 886.4750...Surgical Devices § 886.4750 Ophthalmic eye shield. (a) Identification. An ophthalmic eye shield is a device that consists of a...

2010-04-01

249

30 CFR 57.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Ventilation and shielding for welding. 57.14213 Section 57.14213 Mineral Resources...Procedures § 57.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2011-07-01

250

30 CFR 57.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Ventilation and shielding for welding. 57.14213 Section 57.14213 Mineral Resources...Procedures § 57.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2013-07-01

251

30 CFR 56.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Ventilation and shielding for welding. 56.14213 Section 56.14213 Mineral Resources...Procedures § 56.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2013-07-01

252

30 CFR 56.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Ventilation and shielding for welding. 56.14213 Section 56.14213 Mineral Resources...Procedures § 56.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2014-07-01

253

30 CFR 57.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Ventilation and shielding for welding. 57.14213 Section 57.14213 Mineral Resources...Procedures § 57.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2014-07-01

254

30 CFR 56.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Ventilation and shielding for welding. 56.14213 Section 56.14213 Mineral Resources...Procedures § 56.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2011-07-01

255

30 CFR 56.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Ventilation and shielding for welding. 56.14213 Section 56.14213 Mineral Resources...Procedures § 56.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2012-07-01

256

30 CFR 57.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Ventilation and shielding for welding. 57.14213 Section 57.14213 Mineral Resources...Procedures § 57.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2012-07-01

257

30 CFR 56.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Ventilation and shielding for welding. 56.14213 Section 56.14213 Mineral Resources...Procedures § 56.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2010-07-01

258

30 CFR 57.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Ventilation and shielding for welding. 57.14213 Section 57.14213 Mineral Resources...Procedures § 57.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...

2010-07-01

259

Spacecraft Solar Particle Event (SPE) Shielding: Shielding Effectiveness as a Function of SPE Model as Determined with the FLUKA Radiation Transport Code  

NASA Astrophysics Data System (ADS)

In the this paper, we report the results of modeling and simulation studies in which the radiation transport code FLUKA (FLUktuierende KAskade) is used to determine the changes in total ionizing dose (TID) and single-event effect (SEE) environments behind aluminum, polyethylene, carbon, and titanium shielding masses when the assumed form (i.e., Band or Exponential) of the solar particle event (SPE) kinetic energy spectra is changed. FLUKA simulations are fully three dimensional with an isotropic particle flux incident on a concentric spherical shell shielding mass and detector structure. FLUKA is a fully integrated and extensively verified Monte Carlo simulation package for the interaction and transport of high-energy particles and nuclei in matter. The effects are reported of both energetic primary protons penetrating the shield mass and secondary particle showers caused by energetic primary protons colliding with shielding mass nuclei. SPE heavy ion spectra are not addressed. Our results, in agreement with previous studies, show that use of the Exponential form of the event spectra can seriously underestimate spacecraft SPE TID and SEE environments in some, but not all, shielding mass cases. The SPE spectra investigated are taken from four specific SPEs that produced ground-level events (GLEs) during solar cycle 23 (1997-2008). GLEs are produced by highly energetic solar particle events (ESP), i.e., those that contain significant fluences of 700 MeV to 10 GeV protons. Highly energetic SPEs are implicated in increased rates of spacecraft anomalies and spacecraft failures. High-energy protons interact with Earth’s atmosphere via nuclear reaction to produce secondary particles, some of which are neutrons that can be detected at the Earth’s surface by the global neutron monitor network. GLEs are one part of the overall SPE resulting from a particular solar flare or coronal mass ejection event on the sun. The ESP part of the particle event, detected by spacecraft, is often associated with the arrival of a “shock front” at Earth some hours after the arrival of the GLE. The specific SPEs used in this analysis are those of: 1) November 6, 1997 - GLE only; 2) July 14-15, 2000 - GLE from the 14th plus ESP from the 15th; 3) November 4-6, 2001 - GLE and ESP from the 4th; and 4) October 28-29, 2003 - GLE and ESP from the 28th plus GLE from the 29th. The corresponding Band and Exponential spectra used in this paper are like those previously reported.

Koontz, S. L.; Atwell, W. A.; Reddell, B.; Rojdev, K.

2010-12-01

260

Earth tides  

SciTech Connect

Nineteen papers on gravity, tilt, and strain tides are compiled into this volume. Detailed chapters cover the calculation of the tidal forces and of the Earth's response to them, as well as actual observations of earth tides. Partial Contents: On Earth tides. The tidal forces: Tidal Forces. New Computations of the Tide-Generating Potential. Corrected Tables of Tidal Harmonics. The Theory of Tidal Deformations. Body Tides on an Elliptical, Rotating, Elastic and Oceanless Earth, Deformation of the Earth by Surface Loads. Gravimetric Tidal Loading Computed from Integrated Green's Functions. Tidal Friction in the Solid Earth. Loading Tides Versus Body Tides. Lunar Tidal Acceleration from Earth Satellite Orbit Analysis. Observations: gravity. Tidal Gravity in Britain: Tidal Loading and the Spatial Distribution of the Marine Tide. Tidal Loading along a Profile Europe-East Africa-South Asia-Australia and the Pacific Ocean. Detailed Gravity-Tide Spectrum between One and Four Cycles per Day. Observations: tilt and strain. Cavity and Topographic Effects in Tilt and Strain Measurement. Observations of Local Elastic Effects on Earth Tide Tilts and Strains.

Harrison, J.C.

1984-01-01

261

Earth Impact  

NSDL National Science Digital Library

This activity poses the question: What would happen if a meteor or comet impacted Earth? Students simulate an impact in a container of sand using various-sized rocks, all while measuring, recording and graphing results and conclusions. Then students brainstorm ways to prevent an object from hitting the Earth.

Integrated Teaching And Learning Program

262

Earth meandering  

Microsoft Academic Search

In this paper we try to put away current Global Tectonic Model to look the tectonic evolution of the earth from new point of view. Our new dynamic model is based on study of river meandering (RM) which infer new concept as Earth meandering(EM). In a universal gravitational field if we consider a clockwise spiral galaxy model rotate above Ninety

H. Asadiyan; A. Zamani

2009-01-01

263

International Space Station Radiation Shielding Model Development  

NASA Technical Reports Server (NTRS)

The projected radiation levels within the International Space Station (ISS) have been criticized by the Aerospace Safety Advisory Panel in their report to the NASA Administrator. Methods for optimal reconfiguration and augmentation of the ISS shielding are now being developed. The initial steps are to develop reconfigurable and realistic radiation shield models of the ISS modules, develop computational procedures for the highly anisotropic radiation environment, and implement parametric and organizational optimization procedures. The targets of the redesign process are the crew quarters where the astronauts sleep and determining the effects of ISS shadow shielding of an astronaut in a spacesuit. The ISS model as developed will be reconfigurable to follow the ISS. Swapping internal equipment rack assemblies via location mapping tables will be one option for shield optimization. Lightweight shield augmentation materials will be optimally fit to crew quarter areas using parametric optimization procedures to minimize the augmentation shield mass. The optimization process is being integrated into the Intelligence Synthesis Environment s (ISE s) immersive simulation facility at the Langley Research Center and will rely on High Performance Computing and Communication (HPCC) for rapid evaluation of shield parameter gradients.

Qualls, G. D.; Wilson, J. W.; Sandridge, C.; Cucinotta, F. A.; Nealy, J. E.; Heinbockel, J. H.; Hugger, C. P.; Verhage, J.; Anderson, B. M.; Atwell, W.

2001-01-01

264

Caisson shield for arctic offshore production platform  

SciTech Connect

A caisson shield for the protection of an offshore production platform and, more particularly, a caisson shield for use in an arctic environment for the protection of the offshore structure in iceberg-infested waters which is capable of absorbing the destructive forces of an impact produced by a large iceberg. The caisson shield consists of an essentially annular concrete structure encircling at least the submerged support section of the offshore production platform including vertically upstanding concentrically spaced, annular side walls, a horizontal slab base resting on the marine bottom on which the side walls are supported, and a slab top supported on the side walls, and including annularly spaced internal radial partition walls whereby the entire overall caisson shield structure provides a generally toroidal configuration incorporating a plurality of closed compartments. In one embodiment of the invention, located along the outer annular wall is a plurality of arcuate wall sections forming a series of arches and enclosed compartments between each arcuate wall section and the outer annular wall, which impart a ''scallop-like'' configuration to the outer circumference of the caisson shield. The ''scallop-like'' outer walls are capable of resisting and absorbing extremely high ice loads by being adapted to progressively crush the leading edge of an impacting iceberg and to thereby minimize the crush of the iceberg against the caisson shield before coming to rest against the shield.

Clinton, J. D.; Reusswig, G. H.

1985-03-12

265

Moderately shielded high-Tc SQUID system for rat MCG  

NASA Astrophysics Data System (ADS)

Recently, we have developed a 5-channel high-Tc SQUID system with one signal channel intended for rat magnetocardiography (MCG) in moderately shielded or "quiet" real environment. This system is an adapted version of a human MCG system which has been improved with respect to user-friendliness and stability. A dewar with a cold-warm distance of 7 mm and a refill cycle time of up to one week is utilized. The implemented high-Tc SQUIDs are single-layer devices with grain boundary junctions fabricated at KRISS with laser ablation on 10 mm × 10 mm STO substrates. In order to cancel environmental magnetic noise, three of the five SQUIDs are arranged to build an axial software first-order or second-order gradiometer with a base line of 35 mm. The other two SQUIDs are used for balancing. To overcome previous system instabilities, we have implemented an Earth field compensation for each SQUID. For this, the SQUIDs were mounted in capsules containing integrated field compensation coils. The three Earth field components are measured with an additional triaxial fluxgate, and compensated at the SQUID locations using the low-noise current source of the SQUID readout electronics. This way, the SQUIDs can be cooled and operated in a low residual field that improves system stability and reduces low-frequency SQUID noise. It is even possible to slowly move the dewar in the Earth field (dynamic field compensation). Different noise cancellation procedures were optimized and compared employing a periodic signal source.

Bechstein, S.; Kim, I.-S.; Drung, D.; Novikov, I.; Schurig, Th

2010-06-01

266

Performance of multilayer insulation with slotted shield  

NASA Astrophysics Data System (ADS)

Thermal and evacuating performance can be improved by means of slotting a number of one dimension slots on reflection shields of the multilayer insulation (MLI). The influence of slots on thermal radiation and gas conduction heat fluxes are theoretically studied. Based on the analysis and test, the optimum slot rate and length have been obtained. Experiments also show that the performance of MLI with slotted shield will be further improved if a combination of slotted shields with different slot rate can be used to fit the interstitial pressure distribution.

Chen, Guobang; Sun, Tao; Zheng, Jianyao; Huang, Zhixue; Yu, Jianping

267

The SHIELD Multi-Wavelength Archive  

NASA Astrophysics Data System (ADS)

We present WCS-registered data products from the "Survey of HI in Extremely Low-Mass Dwarfs" (SHIELD). This ALFALFA follow-up program targets sources that inhabit the faint end of the HI luminosity function. The final SHIELD data suite includes UV, optical, infrared, and HI imaging, providing a unique opportunity to study the panchromatic properties of low-mass, gas-rich galaxies. Ongoing analysis of the rotational dynamics and patterns of star formation in these systems will be disseminated in forthcoming manuscripts. The final SHIELD data products will be made available to the public on an archival website.

McNichols, Andrew; Teich, Yaron; Cannon, John M.; Adams, Elizabeth A.; Dolphin, Andrew E.; Elson, Edward C.; Giovanelli, Riccardo; Haynes, Martha P.; McQuinn, Kristen B.; Ott, Juergen; Saintonge, Amelie; Salzer, John Joseph; Skillman, Evan D.

2015-01-01

268

Radiation shielding concrete made of Basalt aggregates.  

PubMed

In spite of the fact that Basalt is a widespread type of rock, there is very little available information on using it as aggregates for concrete radiation shielding. This paper investigates the possibility of using Basalt for the aforementioned purpose. The results have shown that Basalt could be used successfully for preparing radiation shielding concrete, but some attention should be paid to the choice of the suitable types of Basalt and for the neutron activation problem that could arise in the concrete shield. PMID:22933408

Alhajali, S; Yousef, S; Kanbour, M; Naoum, B

2013-04-01

269

Seismic Crystals And Earthquake Shield Application  

E-print Network

We theoretically demonstrate that earthquake shield made of seismic crystal can damp down surface waves, which are the most destructive type for constructions. In the paper, seismic crystal is introduced in aspect of band gaps (Stop band) and some design concepts for earthquake and tsunami shielding were discussed in theoretical manner. We observed in our FDTD based 2D elastic wave simulations that proposed earthquake shield could provide about 0.5 reductions in magnitude of surface wave on the Richter scale. This reduction rate in magnitude can considerably reduce destructions in the case of earthquake.

B. Baykant Alagoz; Serkan Alagoz

2009-02-09

270

Hot cell shield plug extraction apparatus  

DOEpatents

An apparatus is provided for moving shielding plugs into and out of holes in concrete shielding walls in hot cells for handling radioactive materials without the use of external moving equipment. The apparatus provides a means whereby a shield plug is extracted from its hole and then swung approximately 90 degrees out of the way so that the hole may be accessed. The apparatus uses hinges to slide the plug in and out and to rotate it out of the way, the hinge apparatus also supporting the weight of the plug in all positions, with the load of the plug being transferred to a vertical wall by means of a bolting arrangement.

Knapp, Philip A. (Moore, ID); Manhart, Larry K. (Pingree, ID)

1995-01-01

271

Planet Earth  

NSDL National Science Digital Library

How does the Earth work? What is its relationship to the other planets? These are but a few important questions answered by this creative instructional series created by WQED in Pittsburgh, in association with the National Academy of Sciences. The series was designed to present information about "our solar system and Earth's oceans, climate, and mineral and energy sources." The Annenberg Media group has placed this entire series online, and visitors can view all seven installments here. The programs include "The Climate Puzzle", "Gifts from the Earth", and "The Solar Sea". Teachers will note that the site also contains links to other educational resources, reviews, and related resources from the Annenberg Media organization.

1986-01-01

272

Characteristics of Whipple Shield Performance in the Shatter Regime  

NASA Technical Reports Server (NTRS)

Between the onset of projectile fragmentation and the assumption of rear wall failure due to an impulsive load, multi-wall ballistic limit equations are linearly interpolated to provide reasonable yet conservative predictions of perforation thresholds with conveniently simple mathematics. Although low velocity and hypervelocity regime predictions are based on analytical expressions, there is no such scientific foundation for predictions in the intermediate (or shatter) regime. As the debris flux in low earth orbit (LEO) becomes increasingly dominated by manmade pollution, the profile of micrometeoroid and orbital debris (MMOD) risk shifts continually towards lower velocities. For the International Space Station (ISS), encounter velocities below 7 km/s now constitute approximately 50% of the penetration risk. Considering that the transition velocity from shatter to hypervelocity impact regimes described by common ballistic limit equations (e.g. new non-optimum Whipple shield equation [1]) occurs at 7 km/s, 50% of station risk is now calculated based on failure limit equations with little analytical foundation. To investigate projectile and shield behavior for impact conditions leading to projectile fragmentation and melt, a series of hypervelocity impact tests have been performed on aluminum Whipple shields. In the experiments projectile diameter, bumper thickness, and shield spacing were kept constant, while rear wall thickness was adjusted to determine spallation and perforation limits at various impact velocities and angles. The results, shown in Figure 1 for normal and 45 impacts, demonstrated behavior that was not sufficiently described by the simplified linear interpolation of the NNO equation (also shown in Figure 1). Hopkins et al. [2] investigated the performance of a nominally-identical aluminum Whipple shield, identifying the effects of phase change in the shatter regime. The results (conceptually represented in Figure 2) were found to agree well with those obtained in this study at normal incidence, suggesting that shielding performance in the shatter regime could be well described by considering more complex phase conditions than currently implemented in most BLEs. Furthermore, evidence of these phase effects were found in the oblique test results, providing the basis for an empirical description of these effects that can be applied in MMOD risk assessment software. In this paper, results of the impact experiments are presented, and characteristics of target damage are evaluated. A comparison of intermediate velocity impact failure mechanisms in current BLEs are discussed and compared to the findings of the experimental study. Risk assessment calculations have been made on a simplified structure using currently implemented penetration equations and predicted limits from the experimental program, and the variation in perceived mission risk is discussed. It was found that ballistic limit curves that explicitly incorporated phase change effects within the intermediate regime lead to a decrease in predicted MMOD risk for ISS-representative orbits. When considered for all Whipple-based shielding configurations onboard the ISS, intermediate phase change effects could lead to significant variations in predicted mission risk.

Ryan, Shannon; Bjorkman, Michael; Christiansen, Eric L.

2009-01-01

273

Magnetic shielding of interplanetary spacecraft against solar flare radiation  

NASA Technical Reports Server (NTRS)

The ultimate objective of this work is to design, build, and fly a dual-purpose, piggyback payload whose function is to produce a large volume, low intensity magnetic field and to test the concept of using such a magnetic field (1) to protect spacecraft against solar flare protons, (2) to produce a thrust of sufficient magnitude to stabilize low satellite orbits against orbital decay from atmospheric drag, and (3) to test the magsail concept. These all appear to be capable of being tested using the same deployed high temperature superconducting coil. In certain orbits, high temperature superconducting wire, which has now been developed to the point where silver-sheathed high T sub c wires one mm in diameter are commercially available, can be used to produce the magnetic moments required for shielding without requiring any mechanical cooling system. The potential benefits of this concept apply directly to both earth-orbital and interplanetary missions. The usefulness of a protective shield for manned missions needs scarcely to be emphasized. Similarly, the usefulness of increasing orbit perigee without expenditure of propellant is obvious. This payload would be a first step in assessing the true potential of large volume magnetic fields in the US space program. The objective of this design research is to develop an innovative, prototype deployed high temperature superconducting coil (DHTSC) system.

Cocks, Franklin H.; Watkins, Seth

1993-01-01

274

Earth's Surface  

NSDL National Science Digital Library

This self-contained module on Earth's crust includes a range of fun activities that students can perform in the classroom and at home with family members. They impart important concepts such as observation, identification, measurement, and differentiation.

Houghton Mifflin Science

275

Earth Systems  

NSDL National Science Digital Library

This self-contained module on Earth systems includes a range of fun activities that students can perform in the classroom and at home with family members. They impart important concepts such as observation, identification, measurement, and differentiation.

Houghton Mifflin Science

276

Discover Earth  

NASA Technical Reports Server (NTRS)

Discover Earth is a NASA-funded project for teachers of grades 5-12 who want to expand their knowledge of the Earth system, and prepare to become master teachers who promote Earth system science in their own schools, counties, and throughout their state. Participants from the following states are invited to apply: Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Washington, DC. Teachers selected for the project participate in a two-week summer workshop conducted at the University of Maryland, College Park; develop classroom-ready materials during the workshop for broad dissemination; conduct a minimum of two peer training activities during the coming school year; and participate in other enrichment/education opportunities as available and desired. Discover Earth is a team effort that utilizes expertise from a range of contributors, and balances science content with hands-on classroom applications.

1997-01-01

277

Earth Day  

NSDL National Science Digital Library

The State University of New York at Buffalo presents this History of Earth Day website. The goal of the site is that teachers and students can better understand the development and purpose of Earth Day. In addition to the history, SUNY-Buffalo has compiled a series of websites complete with projects associated with Earth Day, appropriate for children, high school students, and college undergrads. Furthermore, the legal aspect of Earth Day - environmental legislation, EPA standards, and Global Climate Change legislation - are also discussed on the site. A list of further sites is also provided if users want more information on this national effort to help solve environmental issues such as pollution, overpopulation, and global warming. Teachers will find this website both informative and helpful in developing appropriate teaching curricula connected to this holiday, while students can have fun learning and creating projects of their own that contribute to preserving the environment.

2007-04-19

278

Design of Reflective, Photonic Shields for Atmospheric Reentry  

NASA Technical Reports Server (NTRS)

We present the design of one-dimensional photonic crystal structures, which can be used as omnidirectional reflecting shields against radiative heating of space vehicles entering the Earth's atmosphere. This radiation is approximated by two broad bands centered at visible and near-infrared energies. We applied two approaches to find structures with the best omnidirectional reflecting performance. The first approach is based on a band gap analysis and leads to structures composed of stacked Bragg mirrors. In the second approach, we optimize the structure using an evolutionary strategy. The suggested structures are compared with a simple design of two stacked Bragg mirrors. Choice of the constituent materials for the layers as well as the influence of interlayer diffusion at high temperatures are discussed.

Komarevskiy, Nikolay; Shklover, Valery; Braginsky, Leonid; Hafner, Christian; Fabrichnaya, Olga; White, Susan; Lawson, John

2010-01-01

279

Visible Earth  

NSDL National Science Digital Library

This site provides a searchable collection of NASA Earth science images, animations and data visualizations. Most images are available at multiple resolutions, with a description of the image and metadata. Users can search the database using full text; or with advanced searches by topic, keyword, sensor, geographic region, parameter, and dates. Examples of topics represented in this collection are snow and ice, agriculture, oceans, climate, the atmosphere, human dimensions, land surface, the solid earth and more.

NASA

280

Technical specifications for the bulk shielding reactor  

SciTech Connect

This report provides information concerning the technical specifications for the Bulk Shielding Reactor. Areas covered include: safety limits and limiting safety settings; limiting conditions for operation; surveillance requirements; design features; administrative controls; and monitoring of airborne effluents. 10 refs.

Not Available

1986-05-01

281

Boron-10 loaded inorganic shielding material  

NASA Technical Reports Server (NTRS)

Shielding material containing Boron 10 and gadoliunium for neutron absorption has been developed to reduce interference from low energy neutrons in measurement of fission neutron spectrum using Li-6 fast neutron spectrometer.

Baker, S. I.; Ryskiewicz, R. S.

1972-01-01

282

Resonance self-shielding methodology in MPACT  

SciTech Connect

The resonance self-shielding methods of the neutron transport code Michigan Parallel Characteristics based Transport (MPACT) are described in this paper. Two resonance-integral table based methods are utilized to resolve the resonance self-shielding effect. The subgroup method is a mature approach used in MPACT as the basic functionality for the resonance calculation. Another new iterative method, named the embedded self-shielding method is also implemented in MPACT. Comparisons of the two methods as well as their numerical verifications are presented. The results show that MPACT is capable of modeling the resonance self-shielding in a variety of PWR benchmarking cases, including difficult fuel lattice cases with poison, control rods or mixed gadolinia fuel rods. (authors)

Liu, Y.; Collins, B.; Kochunas, B.; Martin, W. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI, 48109 (United States); Kim, K. S.; Williams, M. [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831-6172 (United States)

2013-07-01

283

Shield Design for Lunar Surface Applications  

SciTech Connect

A shielding concept for lunar surface applications of nuclear power is presented herein. The reactor, primary shield, reactor equipment and power generation module are placed in a cavity in the lunar surface. Support structure and heat rejection radiator panels are on the surface, outside the cavity. The reactor power of 1,320 kWt was sized to deliver 50 kWe from a thermoelectric power conversion subsystem. The dose rate on the surface is less than 0.6 mRem/hr at 100 meters from the reactor. Unoptimized shield mass is 1,020 kg which is much lighter than a comparable 4{pi} shield weighing in at 17,000 kg.

Johnson, Gregory A. [Pratt and Whitney -- Rocketdyne, Inc., 6633 Canoga Avenue, P.O. Box 7922 MC LA-13, Canoga Park, California 91309-7922 (United States)

2006-01-20

284

Thermal Shield and Reactor Structure Temperatures  

SciTech Connect

The purpose of this report is to present reactor structure and thermal shield temperature data taken during P-3 and P-5 cycles and compare them with design calculations in order to predict temperatures at higher power levels.

Collier, A.R.

2001-07-31

285

Shield Design for Lunar Surface Applications  

NASA Astrophysics Data System (ADS)

A shielding concept for lunar surface applications of nuclear power is presented herein. The reactor, primary shield, reactor equipment and power generation module are placed in a cavity in the lunar surface. Support structure and heat rejection radiator panels are on the surface, outside the cavity. The reactor power of 1,320 kWt was sized to deliver 50 kWe from a thermoelectric power conversion subsystem. The dose rate on the surface is less than 0.6 mRem/hr at 100 meters from the reactor. Unoptimized shield mass is 1,020 kg which is much lighter than a comparable 4? shield weighing in at 17,000 kg.

Johnson, Gregory A.

2006-01-01

286

Investigation of steel--sodium--iron shields  

Microsoft Academic Search

An analysis of experimental data from 21 fast reactor shield configurations containing steel, sodium, and iron were made as part of a study of the upper axial shielding needs of the Clinch River Breeder Reactor. The measured data were analyzed using both one- and two-dimensional discrete ordinates transport codes and several cross section libraries based on ENDF\\/B-IV data with group

E. M. Oblow; R. E. Maerker

1978-01-01

287

X-ray transmissive debris shield  

DOEpatents

A composite window structure is described for transmitting x-ray radiation and for shielding radiation generated debris. In particular, separate layers of different x-ray transmissive materials are laminated together to form a high strength, x-ray transmissive debris shield which is particularly suited for use in high energy fluences. In one embodiment, the composite window comprises alternating layers of beryllium and a thermoset polymer.

Spielman, Rick B. (Albuquerque, NM)

1994-01-01

288

Nuclear reactor shield including magnesium oxide  

DOEpatents

An improvement in nuclear reactor shielding of a type used in reactor applications involving significant amounts of fast neutron flux, the reactor shielding including means providing structural support, neutron moderator material, neutron absorber material and other components as described below, wherein at least a portion of the neutron moderator material is magnesium in the form of magnesium oxide either alone or in combination with other moderator materials such as graphite and iron.

Rouse, Carl A. (Del Mar, CA); Simnad, Massoud T. (La Jolla, CA)

1981-01-01

289

Far infrared spectroscopy telescope (FIRST) inflatable thermal shield, phase 1  

Microsoft Academic Search

Inflatable space rigidized structures (ISRS) were assessed for the FIRST satellite thermal shield. The baseline shield configuration, the so called obliquely cut cylindrical shield configuration, has a diameter of 10 m, a maximum height of 10 m, and a cut angle of 30 deg. This shield consists of an ISRS skeleton of tubes of diameter 0.45 m carrying the thermal

S. Kose

1987-01-01

290

Beam extraction from a synchrotron through a magnetic shield  

Microsoft Academic Search

A new beam extraction scheme from a synchrotron is put forward. The main difference from other schemes of extraction is the use of magnetic shields instead of a septum. Magnetic shields are located in the central dipole magnets of a pulsed chicane. The magnetic shield is a multilayer copper–iron tube. Numerical simulations and experimental results for the magnetic shield are

A. V. Bondarenko; N. A. Vinokurov

2009-01-01

291

Earth: Earth Science and Health  

NASA Technical Reports Server (NTRS)

A major new NASA initiative on environmental change and health has been established to promote the application of Earth science remote sensing data, information, observations, and technologies to issues of human health. NASA's Earth Sciences suite of Earth observing instruments are now providing improved observations science, data, and advanced technologies about the Earth's land, atmosphere, and oceans. These new space-based resources are being combined with other agency and university resources, data integration and fusion technologies, geographic information systems (GIS), and the spectrum of tools available from the public health community, making it possible to better understand how the environment and climate are linked to specific diseases, to improve outbreak prediction, and to minimize disease risk. This presentation is an overview of NASA's tools, capabilities, and research advances in this initiative.

Maynard, Nancy G.

2001-01-01

292

Optimum shell separation for closed axial cylindrical magnetic shields  

NASA Astrophysics Data System (ADS)

The effect of shell separation on the axial shielding with closed double-shell cylindrical shields is investigated numerically. It is found that the optimum shell separation for practical, equal-thickness shields of the above type is considerably smaller than that for transverse spherical and infinitely long cylindrical shields: in most cases, air gaps equal 5%-10% of the inner shell diameter are wide enough to bring the shielding to 90% of its maximum. This indicates that closely spaced axial shields can be used without much sacrifice in performance. Taking into account the computed optimum shell separation for double-shell shields, one can easily optimize and design a compact and effective multishell shield. Based on the numerical study, an analytical approximation is suggested for the axial shielding with narrowly spaced double-shell cylindrical shields.

Paperno, Eugene; Peliwal, Saee; Romalis, Michael V.; Plotkin, Anton

2005-05-01

293

Space Shielding Materials for Prometheus Application  

SciTech Connect

At the time of Prometheus program restructuring, shield material and design screening efforts had progressed to the point where a down-selection from approximately eighty-eight materials to a set of five ''primary'' materials was in process. The primary materials were beryllium (Be), boron carbide (B{sub 4}C), tungsten (W), lithium hydride (LiH), and water (H{sub 2}O). The primary materials were judged to be sufficient to design a Prometheus shield--excluding structural and insulating materials, that had not been studied in detail. The foremost preconceptual shield concepts included: (1) a Be/B{sub 4}C/W/LiH shield; (2) a Be/B{sub 4}C/W shield; (3) and a Be/B{sub 4}C/H{sub 2}O shield. Since the shield design and materials studies were still preliminary, alternative materials (e.g., {sup nal}B or {sup 10}B metal) were still being screened, but at a low level of effort. Two competing low mass neutron shielding materials are included in the primary materials due to significant materials uncertainties in both. For LiH, irradiation-induced swelling was the key issue, whereas for H{sub 2}O, containment corrosion without active chemistry control was key, Although detailed design studies are required to accurately estimate the mass of shields based on either hydrogenous material, both are expected to be similar in mass, and lower mass than virtually any alternative. Unlike Be, W, and B{sub 4}C, which are not expected to have restrictive temperature limits, shield temperature limits and design accommodations are likely to be needed for either LiH or H{sub 2}O. The NRPCT focused efforts on understanding swelting of LiH, and observed, from approximately fifty prior irradiation tests, that either casting ar thorough out-gassing should reduce swelling. A potential contributor to LiH swelling appears to be LiOH contamination due to exposure to humid air, that can be eliminated by careful processing. To better understand LiH irradiation performance and mitigate the risks in LiH development for a project with an aggressive schedule like JIMO, some background or advanced development effort for LiH should be considered for future space reactor projects.

R. Lewis

2006-01-20

294

Shielding of manned space vehicles against protons and alpha particles  

NASA Technical Reports Server (NTRS)

The available information on the shielding of manned space vehicles against protons and alpha particles is summarized. The emphasis is placed on shielding against Van Allen belt protons and against solar-flare protons and alpha particles, but information on shielding against galactic cosmic rays is also presented. The approximation methods for use by nonexperts in the space shielding field are those that are standard in the space shielding literature.

Alsmiller, R. G., Jr.; Santoro, R. T.; Barish, J.; Claiborne, H. C.

1972-01-01

295

A' Brief. History of the Tower Shielding Facility and Tower Shielding Facility  

E-print Network

A' Brief. History of the Tower Shielding Facility and Programs Tower Shielding Facility Hoisting of radiation from reactor. 0 Guyed steel structure 315 feet high 0 Conform to AISC specifications for steel 200 fl with 80 mph wind 0 Two-inch plow steel guys (16) stressed to 75,000 lbs each to minimize tower

296

Savage Earth  

NSDL National Science Digital Library

The Savage Earth website is the on-line companion to the PBS television series of the same name. This site tells the stories of several great natural disasters, particularly the eruption of Mt. Vesuvius in 79 A.D. that destroyed Pompeii and the 1994 earthquake in Kobe, Japan. It contains articles on the earth's crust and plate tectonics, earthquakes, volcanoes, and tsunamis. Each article features photographs, animated drawings, and video clips. For example, the earthquakes article includes animations of types of faults and three different kinds of seismic waves. There is also a question and answer section and links to related sites about geology and natural hazards.

2002-04-24

297

Effects of bumper size on high velocity impact damage to Whipple shield  

NASA Astrophysics Data System (ADS)

With the increasing number of space mission the impact risk on spacecraft at hypervelocity by space debris is increasing A collision with space debris can cause damage to a spacecraft in low Earth orbit For designing spacecraft protection constructions and developing advanced debris shieldsLhypervelocity impact simulation experiments on the ground and the computer simulation of hypervelocity impact is the important means The choice of shields modle sizes is a important step both in the experiments and computer simulation Whipple shields are the basic structure configuration for protecting spacecraft from meteoroid and orbital debris and are still extensively adopted This paper explores the bumper size effects on the damage produced by high velocity impacts on Wipple shields Tests were performed using the non-powder two-stage light gas gun facilities at Hypervelocity Impact Research Center at Harbin Institute of Technology The configuration of Wipple shields consisted of various sizes 1 mm thickness bumpers and constant size 3 mm thickness rear wall with 10 cm space btween the bumper and the rear wall The bumpers used for the tests were made up of 8 12 16 and 20 cm square plate made from 2A12 Aluminum All tests were performed with 4 mm in diameter aluminum projectile at velocity ranging from 1 45 to 1 71 km s The limit velocity of projectile impacting on the Whipple shields in over 0 8 probability of penetration of rear wall in probability of no-penetration of rear wall and on critical penetration condition of rear wall was shown to

Ha, Y.; Guan, G. S.; Pang, B. J.; Zhang, W.

298

Design considerations for a Space Station radiation shield for protection from both man-made and natural sources  

NASA Technical Reports Server (NTRS)

This study was conducted to analyze scenarios involving the use of nuclear-power vehicles in the vicinity of a manned Space Station (SS) in low-earth-orbit (LEO) to quantify their radiological impact to the station crew. In limiting the radiant dose to crew members, mission planners may (1) shut the reactor down prior to reentry, (2) position the vehicle at a prescribed parking distance, and (3) deploy radiation shield about the shutdown reactor. The current report focuses on the third option in which point-kernel gamma-ray shielding calculations were performed for a variety of shield configurations for both nuclear electric propulsion (NEP) and nuclear thermal rocket (NTR) vehicles. For a returning NTR vehicle, calculations indicate that a 14.9 MT shield would be needed to limit the integrated crew exposure to no more than 0.05 Sv over a period of six months (25 percent of the allowable exposure to man-made radiation sources). During periods of low vehicular activity in LEO, the shield may be redeployed about the SS habitation module in order to decrease crew exposures to trapped proton radiations by approximately a factor of 10. The corresponding shield mass required for deployment at a returning NEP vehicle is 2.21 MT. Additional scenarios examined include the radioactivation of various metals as might be found in tools used in EVA activities.

Bolch, Wesley E.; Peddicord, K. Lee; Felsher, Harry; Smith, Simon

1994-01-01

299

Digital Earth - A sustainable Earth  

NASA Astrophysics Data System (ADS)

All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

Mahavir

2014-02-01

300

High-temperature metal purification using a compact, portable rf heating and levitation system on the wake shield  

NASA Technical Reports Server (NTRS)

The potential use of a compact, battery-operated rf levitator and heating system to purify high-temperature melting materials in space is described. The wake shield now being fabricated for the Space Vacuum Epitaxy Center will provide an Ultra-high vacuum (10(exp -14) Torr hydrogen, 10(exp -14) Torr helium, 10(exp -30) Torr oxygen). The use of the wake shield to purify Nb, Ti, W, Ir, and other metals to a purity level not achievable on earth is described.

Hahs, C. A.

1990-01-01

301

Advances in space radiation shielding codes  

NASA Technical Reports Server (NTRS)

Early space radiation shield code development relied on Monte Carlo methods and made important contributions to the space program. Monte Carlo methods have resorted to restricted one-dimensional problems leading to imperfect representation of appropriate boundary conditions. Even so, intensive computational requirements resulted and shield evaluation was made near the end of the design process. Resolving shielding issues usually had a negative impact on the design. Improved spacecraft shield design requires early entry of radiation constraints into the design process to maximize performance and minimize costs. As a result, we have been investigating high-speed computational procedures to allow shield analysis from the preliminary concept to the final design. For the last few decades, we have pursued deterministic solutions of the Boltzmann equation allowing field mapping within the International Space Station (ISS) in tens of minutes using standard Finite Element Method (FEM) geometry common to engineering design methods. A single ray trace in such geometry requires 14 milliseconds and limits application of Monte Carlo methods to such engineering models. A potential means of improving the Monte Carlo efficiency in coupling to spacecraft geometry is given.

Wilson, John W.; Tripathi, Ram K.; Qualls, Garry D.; Cucinotta, Francis A.; Prael, Richard E.; Norbury, John W.; Heinbockel, John H.; Tweed, John; De Angelis, Giovanni

2002-01-01

302

Correlated Uncertainties in Radiation Shielding Effectiveness  

NASA Technical Reports Server (NTRS)

The space radiation environment is composed of energetic particles which can deliver harmful doses of radiation that may lead to acute radiation sickness, cancer, and even death for insufficiently shielded crew members. Spacecraft shielding must provide structural integrity and minimize the risk associated with radiation exposure. The risk of radiation exposure induced death (REID) is a measure of the risk of dying from cancer induced by radiation exposure. Uncertainties in the risk projection model, quality factor, and spectral fluence are folded into the calculation of the REID by sampling from probability distribution functions. Consequently, determining optimal shielding materials that reduce the REID in a statistically significant manner has been found to be difficult. In this work, the difference of the REID distributions for different materials is used to study the effect of composition on shielding effectiveness. It is shown that the use of correlated uncertainties allows for the determination of statistically significant differences between materials despite the large uncertainties in the quality factor. This is in contrast to previous methods where uncertainties have been generally treated as uncorrelated. It is concluded that the use of correlated quality factor uncertainties greatly reduces the uncertainty in the assessment of shielding effectiveness for the mitigation of radiation exposure.

Werneth, Charles M.; Maung, Khin Maung; Blattnig, Steve R.; Clowdsley, Martha S.; Townsend, Lawrence W.

2013-01-01

303

Asymmetric Electrostatic Radiation Shielding for Spacecraft  

NASA Technical Reports Server (NTRS)

A paper describes the types, sources, and adverse effects of energetic-particle radiation in interplanetary space, and explores a concept of using asymmetric electrostatic shielding to reduce the amount of such radiation impinging on spacecraft. Typically, such shielding would include a system of multiple inflatable, electrically conductive spheres deployed in clusters in the vicinity of a spacecraft on lightweight structures that would maintain the spheres in a predetermined multipole geometry. High-voltage generators would maintain the spheres at potential differences chosen in conjunction with the multipole geometry so that the resulting multipole field would gradually divert approaching energetic atomic nuclei from a central region occupied by the spacecraft. The spheres nearest the center would be the most positive, so as to repel the positively charged impinging nuclei from the center. At the same time, the monopole potential of the overall spacecraft-and-shielding system would be made negative so as to repel thermal electrons. The paper presents results of computational simulations of energetic-particle trajectories and shield efficiency for a trial system of 21 spheres arranged in three clusters in an overall linear quadrupole configuration. Further development would be necessary to make this shielding concept practical.

Metzger, Philip T.; Youngquist, Robert C.; Lane, John E.

2005-01-01

304

Faraday Shield Development on DIII--D  

NASA Astrophysics Data System (ADS)

DIII--D has been the proving ground for a number of innovative Faraday shield developments over the past ten years. The first Faraday shield used had two tiers of copper-plated Inconel rods of circular cross section with 3 mm thick graphite tiles brazed to the plasma-facing side of the front tier. Later antennas used shields with thin coatings of Ti (C,N) and boron carbide. All the coatings proved effective in reducing impurity influx from the antennas during RF operation. There are two shield designs in use currently. One is a single-tier of horizontal Inconel rods with a 6 ?m layer of boron carbide applied by physical vapor deposition. The other design has molybdenum rods with a plasma-sprayed boron carbide coating approximately 100 ?m thick. Based on comparative performance the thinner coating obtained with physical vapor deposition is preferred for future applicatrions. All Faraday shields have been passively cooled. Future plans call for tests of vanadium elements and of porous-metal helium-cooled elements.

Baity, F. W.; Goulding, R. H.; Hoffman, D. J.; Ryan, P. M.; Taylor, D. J.; Callis, R. W.; Pinsker, R. I.; Lindemuth, J. E.; Rosenfeld, J. H.

1997-11-01

305

Earth's Water  

NSDL National Science Digital Library

This resource provides an overview of the distribution and occurence of water on Earth. Topics include where and how much water there is, the water cycle, and how water is measured. There is also discussion of characteristics and distribution of surface water, groundwater, glaciers, and icecaps.

306

Earth Structures  

NSDL National Science Digital Library

This web guide explores several natural phenomena that are constantly changing the face of the Earth. These geologic forces not only impact the physical features of our planet but ultimately affect the biosphere in a dramatic way. Historically, the changes have ranged from gradual (such as with the process of mountain building) to the spontaneous (such as with seismic events).

National Science Teachers Association (NSTA)

2005-04-01

307

Earth Movers  

NSDL National Science Digital Library

This lesson explores plate tectonics and helps students understand how mountains, earthquakes, and volcanoes are related to the movements of plates. Students will learn about the idea of continental drift and the theory of plate tectonics to ascertain a fuller picture of how land formations on the surface of the Earth are shaped by plates moving below the surface.

308

Visible Earth  

NSDL National Science Digital Library

This Web site provides a searchable directory of NASA Earth science images, animations and data visualizations. Most resources are available digitally at multiple resolutions, with captions and metadata. Users can search the database using full text and advanced searches by topic, keyword, sensor, location, parameter, and dates.

2001-01-01

309

Impact Earth  

NSDL National Science Digital Library

This planetarium show teaches about meteors, meteorites, asteroids, and comets. It includes results from NASA missions and about the dangers they can pose to life on Earth. It is created for full-dome theaters but can also be shown in flat version for TVs and computer monitors. Shows the effects of the Chixulub and Tungusta events, plus the Pallasite impact that resulted in the Brenham meteorite fall. Describes ways that asteroid hunters seek new objects in the Solar System, and how ground-penetrating radar is used to find meteorites that have reached the Earth's surface and ancient craters under the desert. Narrated by astronaut Tom Jones, it also discusses ways that humans might try to deflect an asteroid or comet that is on a collision course with Earth. Created for informal science venues (digital planetariums), it is also useful as ancillary material for middle school science. Created under NASA Cooperative Agreement NCC5-316 to Rice University in conjunction with the Houston Museum of Natural Science as part of the "Immersive Earth" project, part of the REASoN program.

Reiff, Patricia

2009-05-01

310

Earth meandering  

NASA Astrophysics Data System (ADS)

In this paper we try to put away current Global Tectonic Model to look the tectonic evolution of the earth from new point of view. Our new dynamic model is based on study of river meandering (RM) which infer new concept as Earth meandering(EM). In a universal gravitational field if we consider a clockwise spiral galaxy model rotate above Ninety East Ridge (geotectonic axis GA), this system with applying torsion field (likes geomagnetic field) in side direction from Rocky Mt. (west geotectonic pole WGP) to Tibetan plateau TP (east geotectonic pole EGP),it seems that pulled mass from WGP and pushed it in EGP due to it's rolling dynamics. According to this idea we see in topographic map that North America and Green land like a tongue pulled from Pacific mouth toward TP. Actually this system rolled or meander the earth over itself fractaly from small scale to big scale and what we see in the river meandering and Earth meandering are two faces of one coin. River transport water and sediments from high elevation to lower elevation and also in EM, mass transport from high altitude-Rocky Mt. to lower altitude Himalaya Mt. along 'S' shape geodetic line-optimum path which connect points from high altitude to lower altitude as kind of Euler Elastica(EE). These curves are responsible for mass spreading (source) and mass concentration (sink). In this regard, tiltness of earth spin axis plays an important role, 'S' are part of sigmoidal shape which formed due to intersection of Earth rolling with the Earth glob and actual feature of transform fault and river meandering. Longitudinal profile in mature rivers as a part of 'S' curve also is a kind of EE. 'S' which bound the whole earth is named S-1(S order 1) and cube corresponding to this which represent Earth fracturing in global scale named C-1(cube order 1 or side vergence cube SVC), C-1 is a biggest cycle of spiral polygon, so it is not completely closed and it has separation about diameter of C-7. Inside SVC we introduce cone vergence cube (CVC or geotectonic equator GE) which rotate 45 degree counterclockwise with respect to SVC. Every cube from big scale to small scale fractalize in order of 23 and every '8' shape from big scale to small scale also fractalize in the same order. Three dimensional and fractoscopic imagination about understanding the changing on earth is very important so we should imagine '8' as curved surface, sea floor spreading happened in maximum curvature of these surfaces. '8' formed from pair 'S' string with opposite direction. '8' oscillate in Pole-Pole and Side-Side direction and have saddle geometry with two 'U' path along perpendicular saddle (e.g. Lut/Jazmurian and Helmand/Mashkal basin in Iran actually intersection of this saddle shape with the earth surface and Iceland /Black Sea and CapeVerde/Victoria Lake are also In/Out (small scale polygon) of 'U' shape conduit which followed axial saddle of Side-'S-2' and Okhotsk Sea /Balkhash Lake followed axial saddle conduit of Pole-'S-2' actually intersection of this perpendicular conduit with surface make spot-like-lakes/volcanoes or basin. Global EM in Side-S-1 bounded compression region-TP inside and tension region-East African Rift offside).This is a interesting competing between two kinematic geometry - spherical and isometrical geometry by using the interaction of them we can analyze the earth face in past, present and future apart of the forces that cause this face. C-1 in two dimensional look like six sided big tent which speared over Tibet and main rod driven along GA. Pair S-1 curve. have seven component(fold) and six segment in between,S-7 exactly located on TP(center of S-1). Between two successive fold we have complex geology(e.g. eastern Iran and Afghanistan)mass dragged from North America and Siberian and accumulated gradually during six step in Earth Foundation(Tibet),S-7 bounded Takla Makan Desert (in smaller loop) and TP (in bigger loop) S-7 alter the earth balance and responsible for earth disturbing, another sample of 'S' curve we see around Australia and Kermadec/Tonga Trench, Aleutian ri

Asadiyan, H.; Zamani, A.

2009-04-01

311

Electronics Shielding and Reliability Design Tools  

NASA Technical Reports Server (NTRS)

It is well known that electronics placement in large-scale human-rated systems provides opportunity to optimize electronics shielding through materials choice and geometric arrangement. For example, several hundred single event upsets (SEUs) occur within the Shuttle avionic computers during a typical mission. An order of magnitude larger SEU rate would occur without careful placement in the Shuttle design. These results used basic physics models (linear energy transfer (LET), track structure, Auger recombination) combined with limited SEU cross section measurements allowing accurate evaluation of target fragment contributions to Shuttle avionics memory upsets. Electronics shielding design on human-rated systems provides opportunity to minimize radiation impact on critical and non-critical electronic systems. Implementation of shielding design tools requires adequate methods for evaluation of design layouts, guiding qualification testing, and an adequate follow-up on final design evaluation including results from a systems/device testing program tailored to meet design requirements.

Wilson, John W.; ONeill, P. M.; Zang, Thomas A., Jr.; Pandolf, John E.; Koontz, Steven L.; Boeder, P.; Reddell, B.; Pankop, C.

2006-01-01

312

Overview of SNS accelerator shielding analyses  

SciTech Connect

The Spallation Neutron Source is an accelerator driven neutron scattering facility for materials research. During all phases of SNS development, including design, construction, commissioning and operation, extensive neutronics work was performed in order to provide adequate shielding, to assure safe facility operation from radiation protection point of view, and to optimize performance of the accelerator and target facility. Presently, most of the shielding work is concentrated on the beam lines and instrument enclosures to prepare for commissioning, safe operation and adequate radiation background in the future. Although the accelerator is built and in operation mode, there is extensive demand for shielding and activation analyses. It includes redesigning some parts of the facility, facility upgrades, designing additional structures, storage and transport containers for accelerator structures taken out of service, and performing radiation protection analyses and studies on residual dose rates inside the accelerator. (authors)

Popova, I.; Gallmeier, F. X.; Ferguson, P.; Iverson, E.; Lu, W. [ORNL/SNS, MS6475, PO Box 2008, Oak Ridge, TN 37831-6471 (United States)

2012-07-01

313

Radiation shielding effectiveness of newly developed superconductors  

NASA Astrophysics Data System (ADS)

Gamma ray shielding effectiveness of superconductors with a high mass density has been investigated. We calculated the mass attenuation coefficients, the mean free path (mfp) and the exposure buildup factor (EBF). The gamma ray EBF was computed using the Geometric Progression (G-P) fitting method at energies 0.015-15 MeV, and for penetration depths up to 40 mfp. The fast-neutron shielding effectiveness has been characterized by the effective neutron removal cross-section of the superconductors. It is shown that CaPtSi3, CaIrSi3, and Bi2Sr2Ca1Cu2O8.2 are superior shielding materials for gamma rays and Tl0.6Rb0.4Fe1.67Se2 for fast neutrons. The present work should be useful in various applications of superconductors in fusion engineering and design.

Singh, Vishwanath P.; Medhat, M. E.; Badiger, N. M.; Saliqur Rahman, Abu Zayed Mohammad

2015-01-01

314

Phenomenological calculations of shielding spallation neutron sources  

NASA Astrophysics Data System (ADS)

The high level of radiation generated by a spallation source requires the design of an appropriate shielding to surround the source in order to fulfill radiation protection standards. A calculation of the spallation neutron attenuation is presented for various shielding materials, using a phenomenological model, based on the Moyer model. In the first step of the calculation, the interaction length of neutrons for each neutron energy and shielding material was estimated using inelastic cross-sections. In the second step the calculation deals with the attenuation of the neutron flux applying the Moyer model, for each material and neutron energy region. The transmission factors were calculated and compared with experimental data collected from the "Gamma-2" and the "E+T" projects running in JINR (Dubna, Russia). The results of the present work were also compared to the data obtained by different Monte Carlo codes such as MORSE, MCNPX, MARS14 and LAHET.

Fragopoulou, M.; Zamani, M.

2013-06-01

315

High purity silica reflective heat shield development  

NASA Technical Reports Server (NTRS)

A hyperpure vitreous silica material is being developed for use as a reflective and ablative heat shield for planetary entry. Various purity grades and forms of raw materials were evaluated along with various processing methods. Slip casting of high purity grain was selected as the best processing method, resulting in a highly reflective material in the wavelength bands of interest (the visible and ultraviolet regions). The selected material was characterized with respect to optical, mechanical and physical properties using a limited number of specimens. The process has been scaled up to produce a one-half scale heat shield (18 in. dia.) (45.72 cm) for a Jupiter entry vehicle. This work is now being extended to improve the structural safety factor of the heat shield by making hyperpure silica material tougher through the addition of silica fibers.

Nachtscheim, P. R.; Blome, J. C.

1976-01-01

316

First Wall, Blanket, Shield Engineering Technology Program  

SciTech Connect

The First Wall/Blanket/Shield Engineering Technology Program sponsored by the Office of Fusion Energy of DOE has the overall objective of providing engineering data that will define performance parameters for nuclear systems in advanced fusion reactors. The program comprises testing and the development of computational tools in four areas: (1) thermomechanical and thermal-hydraulic performance of first-wall component facsimiles with emphasis on surface heat loads; (2) thermomechanical and thermal-hydraulic performance of blanket and shield component facsimiles with emphasis on bulk heating; (3) electromagnetic effects in first wall, blanket, and shield component facsimiles with emphasis on transient field penetration and eddy-current effects; (4) assembly, maintenance and repair with emphasis on remote-handling techniques. This paper will focus on elements 2 and 4 above and, in keeping with the conference participation from both fusion and fission programs, will emphasize potential interfaces between fusion technology and experience in the fission industry.

Nygren, R.E.

1982-01-01

317

Radiation shielding materials characterization in the MoMa-Count program and further evolutions  

NASA Astrophysics Data System (ADS)

In the frame of the space research programme MoMa (From Molecules to Man) -Count (Coun-termeasures), funded by the Italian Space Agency, multi-functional protections for human space exploration have been investigated, paying particular attention to flexible materials, selected also for their excellent structural, thermal and ballistic performances. Flexible materials such as Kevlar R are qualified for space application, but have poorly known space radiation prop-erties, with consequent uncertainties about their shielding efficiency against the radiation en-vironment. The necessary evaluation of their shielding efficiency has been chiefly based on dedicated ground experiments in accelerators, supplemented by Monte Carlo simulations of the particle transport in the materials or multi-layers. In addition, flight experiments have been performed in Low Earth Orbit (LEO), onboard the International Space Station (ISS) and the re-entry capsule Foton, to measure the shielding behaviour in the actual operating environment of space, via dedicated detectors and dosimeters. This paper aims at presenting the results and lessons learned accrued within the MoMa-Count program, as well as the future actions planned for improving radiation shielding in long duration human exploration missions.

Lobascio, Cesare

318

Paleoproterozoic thermotectogenesis: A rotation-plume model of the formation of the Aldan Shield  

NASA Astrophysics Data System (ADS)

The Aldan Shield—the southern segment of the Aldan-Stanovoi sialic nuclear, 1100 km in diameter—is subdivided into an inner granulite-gneiss and an outer amphibolite-gneiss domain. This heterogeneity arose in the Paleoproterozoic as a result of thermotectogenesis, i.e., the sum of magmatism, metamorphism, and deformation superimposed on the older Archean crust. In addition to metamorphic heterogeneity, the main consequences of the Paleoproterozoic thermotectogenesis comprised the emplacement of mafic dikes of various ages and the centrifugal evolution of a radial tectonomagmatic system consisting of complementary granitoids and anorthosites. Thermotectogenesis proceeded in a pulsatory manner with alternation of extension and compression settings in the near-equatorial epi-Archean supercontinent. These consequences and the mechanism of pulsatory evolution are described by a model of plume-related underplating in combination with the change of the Earth’s rotation in the regime of oscillatory evolution of the Earth-Moon system.

Glukhovsky, M. Z.

2009-05-01

319

Scale-PC shielding analysis sequences  

SciTech Connect

The SCALE computational system is a modular code system for analyses of nuclear fuel facility and package designs. With the release of SCALE-PC Version 4.3, the radiation shielding analysis community now has the capability to execute the SCALE shielding analysis sequences contained in the control modules SAS1, SAS2, SAS3, and SAS4 on a MS- DOS personal computer (PC). In addition, SCALE-PC includes two new sequences, QADS and ORIGEN-ARP. The capabilities of each sequence are presented, along with example applications.

Bowman, S.M.

1996-05-01

320

Tectonic evolution of the Western Australian Shield  

NASA Technical Reports Server (NTRS)

Geological and geochronological studies in the Western Australian Shield were updated. This terrane bears many similarities to the Indian Shield since they were neighboring parts of Gondwanaland. Western Australia consists of two cratons (Pilbara and Yilgarn) and four orogenic belts (Capricorn, Pingarra, Albany-Fraser, and Patterson), as well as some relatively young (1.6 to 0.75 Ga) sedimentary rocks. The two cratonic blocks are both older than about 2.5 Ga, and the orogenic belts range in age from 2.0 to 0.65 Ga.

Myers, John S.

1988-01-01

321

Blue Cross and Blue Shield of Alabama  

NSDL National Science Digital Library

The Alabama BlueCross and BlueShield Medical Information Server, located and developed by the University of Alabama at Birmingham Department of Computer and Information Sciences, through a grant from Blue Cross and Blue Shield of Alabama for the express purpose of providing Internet access to medical information for all physicians and other health care providers in the state of Alabama. It provides links to a broad range of medical information resources located throughout the Internet. Menus provide information on diseases and disorders, patient care and medical practice, medical specialties, journals and newsletters, health care reform, and other medical information.

1997-01-01

322

Hysteresis prediction inside magnetic shields and application  

NASA Astrophysics Data System (ADS)

We have developed a simple model that is able to describe and predict hysteresis behavior inside Mumetal magnetic shields, when the shields are submitted to ultra-low frequency (<0.01 Hz) magnetic perturbations with amplitudes lower than 60 ?T. This predictive model has been implemented in a software to perform an active compensation system. With this compensation the attenuation of longitudinal magnetic fields is increased by two orders of magnitude. The system is now integrated in the cold atom space clock called PHARAO. The clock will fly onboard the International Space Station in the frame of the ACES space mission.

Mori?, Igor; De Graeve, Charles-Marie; Grosjean, Olivier; Laurent, Philippe

2014-07-01

323

Hysteresis prediction inside magnetic shields and application.  

PubMed

We have developed a simple model that is able to describe and predict hysteresis behavior inside Mumetal magnetic shields, when the shields are submitted to ultra-low frequency (<0.01 Hz) magnetic perturbations with amplitudes lower than 60??T. This predictive model has been implemented in a software to perform an active compensation system. With this compensation the attenuation of longitudinal magnetic fields is increased by two orders of magnitude. The system is now integrated in the cold atom space clock called PHARAO. The clock will fly onboard the International Space Station in the frame of the ACES space mission. PMID:25085183

Mori?, Igor; De Graeve, Charles-Marie; Grosjean, Olivier; Laurent, Philippe

2014-07-01

324

Save the Earth vs Destroy the Earth  

E-print Network

Abstract. Save the Earth VS Destroy the Earth is an interactive installation. Two structures, built with the skeletons of old monitors, are holding two world globes, plus a sign indicating on one Save the Earth and on the other Destroy the Earth. The audience is invited to mime the action to save or destroy the Earth becoming a part of the artwork. Every action is monitored and photographed, leading to the creation of an image dataset of save-the-earth vs destroy-the-earth actions. Such dataset can be interpreted as sort of sentiment dataset, where actors express a negative or positive sentiment about the "Save the Earth " topic.

Davide Giaccone

325

Breathing Earth  

NSDL National Science Digital Library

Visual simulation and representation programs and applications have been popping up online in greater numbers, and this recent find is one that will pique the interest of scientists, policy makers, and others who are concerned about carbon dioxide emission rates across the Earth. The Breathing Earth site was created by David Bleja, and he draws on a number of resources (such as the World Factbook and the United Nations) for the data that is utilized to create this site. Visitors can scroll over different countries to learn about their population, their emissions, and their birth and death rate. This interactive map and educational resource also contains a legend in the right-hand corner which explains the various symbols in use here.

Bleja, David

326

Earth Institute  

NSDL National Science Digital Library

The mission of the Earth Institute at Columbia University is to help the world achieve sustainability by expanding understanding of the Earth as one integrated system. Through research, education, and the practical application of research to real-world challenges, the Institute addresses nine interconnected global issues: climate and society, water, energy, poverty, ecosystems, public health, food and nutrition, and hazards and urbanization. The Institute's site offers a collection of videotaped events, including the biannual "State of the Planet" conferences, 2002-08, a Distinguished Lecture series, and the Sustainable Development seminar series, as well as e-seminars and e-briefings, information about funding opportunities, and information about educational opportunities at Columbia.

327

Earth Math  

NSDL National Science Digital Library

This text explores a few of the many concepts that frequently come up in the study of Earth systems and global climate change. Students will be exposed to many problems involving unit conversion. Global climate change reports involve terms such as kilowatt-hour, megawatt-hour, and gigawatt-hour, as well as megatons and gigatons. Students will become versed in converting units where appropriate, and through the calculations, will work with the concept of significant figures. Creating linear equations from graphical and tabular information is covered, as well as forecasting. The text is meant to be used as a companion to standard Earth science and mathematics courses, and presents enough application problems to allow students to quantitatively understand typical media reports about global climate change.

2009-01-01

328

Impact: Earth!  

NSDL National Science Digital Library

What would happen if a large meteorite or other object hit the Earth? It's something that has engaged the minds and talents of astrophysicists (and students of all ages) for decades. Now the generally curious can create their own simulated impact with Purdue University's "Impact Earth" website. Visitors can browse the Famous Craters area to get started. This part includes some "classics," such as the Ries Crater and the Tunguska Fireball. Of course, visitors really must use the handy interface to craft their own impact, projectile, and target parameters to get the full effect on how such an event plays out. Also, the site includes a complete Documentation file (a peer-reviewed article) and a detailed glossary.

2013-01-01

329

Earth Lab  

NSDL National Science Digital Library

Earth Lab is a database of fossils, minerals and rocks from the UK. A photograph is displayed for each specimen selected, as well as the scientific name, location and properties or age of the specimen. The fossils can be searched by area, age, and group; minerals by area, element, group, and property; and rocks by area, geological age, and type of rock. A series of questions allows users to identify their own specimens.

330

Earth Observations  

NASA Technical Reports Server (NTRS)

This document is concentrates on a couple of the missions where the Spacelab hardware was used to do Earth science. The Atmospheric Laboratory for Applications and Science (ATLAS) series of missions and the Lidar in-Space Technology Experiment (LITE) mission, the ATLAS being a series of three Shuttle missions that were very much Spacelab missions, are described. A little bit about the history, what the missions were, some of the instruments that were on them, and results are given.

Kaye, Jack

2000-01-01

331

Earth Rocks!  

NSDL National Science Digital Library

The purpose of this lesson is to introduce students to the basic elements of our Earth's crust: rocks, soils and minerals. They learn how we categorize rocks, soils and minerals and how they are literally the foundation for our civilization. Students also explore how engineers use rocks, soils and minerals to create the buildings, roads, vehicles, electronics, chemicals, and other objects we use to enhance our lives.

Integrated Teaching And Learning Program

332

Earth's Biomes  

NSDL National Science Digital Library

What are the characteristics of Earth's biomes? First, open the Biomes Graphic Organizer Now read through Information on Aquatic Biome (Freshwater) and fill in 5 characterestics of a freshwater biome in your graphic organizer. Now read through Information on Desert and fill in 5 characteristics of a desert biome in your graphic organizer. Now read through Information on Rainforest and fill in 5 characteristics of rainforest biome in your graphic organizer. Now ...

Ms. Allman

2012-04-05

333

Earth Observatory  

NSDL National Science Digital Library

This Web site includes shares the images, stories and discoveries that emerge from NASA Earth science research, including its satellite missions, in-the-field research and climate models. View global maps of NASA data, check out the Image of the Day and images of current events, and read feature articles and blogs. Also includes special collections of NASA images, including the World of Change series, which documents how our planetâs land, oceans, atmosphere and Sun are changing over time.

2011-01-01

334

Earth Day  

NSDL National Science Digital Library

Wow! Endagered species are everywhere! Just understanding the needs of animals will help them to survive longer. Find out how much your use of energy leaves a 'carbon' footprint on the earth. We all need to use our limited resources wisely. Reduce your footprint! Find out how and take the carbon footrpint quiz here. Carbon Footprint Watch the following YouTube video to hear a special message from Carl Hiaasen, the ...

Mrs. Datwyler

2010-04-19

335

Impact Earth  

NSDL National Science Digital Library

This 24 minute planetarium show teaches about meteors, meteorites, asteroids, and comets. The show was created for fulldome theaters, but is also available on DVD to be shown in flat version for TVs and computer monitors, and can be freely viewed online. It shows the effects of the Chixulub and Tungusta events, plus the Pallasite impact that resulted in the Brenham meteorite fall, and describes ways that asteroid hunters seek new objects in the solar system, and how ground penetrating radar is used to find meteorites that have survived to the Earth's surface. Narrated by astronaut Tom Jones, it also discusses ways that humans might try to deflect an asteroid or comet that is on a collision course with Earth. The show was created for informal science venues (digital planetariums); it is also useful as supplemental material for middle school science. Impact Earth is available for free if presented directly from the Space Update site (widescreen or fisheye views linked from YouTube). Otherwise, a DVD of the show can be purchased for $10.

336

Structural and Radiation Shielding Properties of a Martian Habitat Material Synthesized From In-Situ Resources  

NASA Technical Reports Server (NTRS)

The 2 primary requirements of a Martian habitat structure include sufficient structural integrity and effective radiation shielding. In addition, the capability to synthesize such building materials primarily from in-situ resources would significantly reduce the cost associated with transportation of such materials and structures from earth. To demonstrate the feasibility of such an approach we have fabricated samples in the laboratory using simulated in-situ resources, evaluated radiation shielding effectiveness using radiation transport codes and radiation test data, and conducted mechanical properties testing. In this paper we will present experimental results that demonstrate the synthesis of polyethylene from a simulated Martian atmosphere and the fabrication of a composite material using simulated Martian regolith with polyethylene as the binding material. Results from radiation transport calculations and data from laboratory radiation testing using a 500 MeV/nucleon Fe beam will be discussed. Mechanical properties of the proposed composite as a function of composition and processing parameters will also be presented.

Sen, S.; Caranza, S.; Bhattacharya, M.; Makel, D. B.

2006-01-01

337

DNA fragmentation induced by Fe ions in human cells: shielding influence on spatially correlated damage  

NASA Technical Reports Server (NTRS)

Outside the magnetic field of the Earth, high energy heavy ions constitute a relevant part of the biologically significant dose to astronauts during the very long travels through space. The typical pattern of energy deposition in the matter by heavy ions on the microscopic scale is believed to produce spatially correlated damage in the DNA which is critical for radiobiological effects. We have investigated the influence of a lucite shielding on the initial production of very small DNA fragments in human fibroblasts irradiated with 1 GeV/u iron (Fe) ions. We also used gamma rays as reference radiation. Our results show: (1) a lower effect per incident ion when the shielding is used; (2) an higher DNA Double Strand Breaks (DSB) induction by Fe ions than by gamma rays in the size range 1-23 kbp; (3) a non-random DNA DSB induction by Fe ions. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

Antonelli, F.; Belli, M.; Campa, A.; Chatterjee, A.; Dini, V.; Esposito, G.; Rydberg, B.; Simone, G.; Tabocchini, M. A.

2004-01-01

338

Solar-Flare Shielding With Regolith at  

E-print Network

Solar-Flare Shielding With Regolith at a Lunar-Base Site _T jo_m E. Nealy, John W. Wilson are envisioned, environmental parameters such as high-energy, charged-particle radiation from solar flares and galactic cosmic rays become very impor- tant. Large solar flares can release great quantities of high-energy

Rathbun, Julie A.

339

Passive magnetic shielding in static gradient fields  

NASA Astrophysics Data System (ADS)

The effect of passive magnetic shielding on dc magnetic field gradients imposed by both external and internal sources is studied for two idealized shield models: concentric spherical and infinitely-long cylindrical shells of linear material. It is found that higher-order multipoles of an externally applied magnetic field are always shielded progressively better for either geometry by a factor related to the order of the multipole. In regard to the design of internal coil systems, we determine reaction factors for the general multipole field and provide examples of how one can take advantage of the coupling of the coils to the innermost shell to optimize the uniformity of the field. Furthermore, we provide formulae relevant to active magnetic compensation systems which attempt to stabilize the interior fields by sensing and cancelling the exterior fields close to the outermost shell. Overall this work provides a comprehensive framework that is useful for the analysis and optimization of dc magnetic shields, serving as a theoretical and conceptual design guide as well as a starting point and benchmark for finite-element analysis.

Bidinosti, C. P.; Martin, J. W.

2014-04-01

340

Radiation shielding device for nuclear facilities  

Microsoft Academic Search

A pressure vessel of a nuclear reactor is bodily enclosed by an inner layer made of a heat insulating material and an outer layer made of a radiation shielding material, and a nozzle joined by welding to the pressure vessel and a pipe joined by welding to the nozzle projected outwardly from the pressure vessel to extend through openings formed

Aoki

1978-01-01

341

Radiation Shielding for Manned Deep Space Missions  

NASA Technical Reports Server (NTRS)

The arrival of the Expedition 1 Crew at the International Space Station represents the beginning of the continuous presence of man in space. Already we are deploying astronauts and cosmonauts for missions of approx. 6 months onboard the ISS. In the future we can anticipate that more people will be in space and they will be there for longer periods. Even with 6-months deployments to the ISS, the radiation exposure that crew members receive is approaching the exposure limits imposed by the governments of the space- faring nations. In the future we can expect radiation protection to be a dominant consideration for long manned missions. Recognizing this, NASA has expanded their research program on radiation health. This program has three components, bioastronautics, fundamental biology and radiation shielding materials. Bioastronautics is concerned with the investigating the effects of radiation on humans. Fundamental biology investigates the basic mechanisms of radiation damage to tissue. Radiation shielding materials research focuses on developing accurate computational tools to predict the radiation shielding effectiveness of materials. It also investigates new materials that can be used for spacecraft. The radiation shielding materials program will be described and examples of results from the ongoing research will be shown.

Adams, James H., Jr.

2003-01-01

342

Ford Motor Company NDE facility shielding design.  

PubMed

Ford Motor Company proposed the construction of a large non-destructive evaluation laboratory for radiography of automotive power train components. The authors were commissioned to design the shielding and to survey the completed facility for compliance with radiation doses for occupationally and non-occupationally exposed personnel. The two X-ray sources are Varian Linatron 3000 accelerators operating at 9-11 MV. One performs computed tomography of automotive transmissions, while the other does real-time radiography of operating engines and transmissions. The shield thickness for the primary barrier and all secondary barriers were determined by point-kernel techniques. Point-kernel techniques did not work well for skyshine calculations and locations where multiple sources (e.g. tube head leakage and various scatter fields) impacted doses. Shielding for these areas was determined using transport calculations. A number of MCNP [Briesmeister, J. F. MCNPCA general Monte Carlo N-particle transport code version 4B. Los Alamos National Laboratory Manual (1997)] calculations focused on skyshine estimates and the office areas. Measurements on the operational facility confirmed the shielding calculations. PMID:16604635

Metzger, Robert L; Van Riper, Kenneth A; Jones, Martin H

2005-01-01

343

New shield for gamma-ray spectrometry  

NASA Technical Reports Server (NTRS)

Gamma-ray shield that can be evacuated, refilled with a clean gas, and pressurized for exclusion of airborne radioactive contaminants effectively lowers background noise. Under working conditions, repeated evacuation and filling procedures have not adversely affected the sensitivity and resolution of the crystal detector.

Brar, S. S.; Gustafson, P. F.; Nelson, D. M.

1969-01-01

344

Performance of multilayer insulation with slotted shield  

Microsoft Academic Search

Thermal and evacuating performance can be improved by means of slotting a number of one dimension slots on reflection shields of the multilayer insulation (MLI). The influence of slots on thermal radiation and gas conduction heat fluxes are theoretically studied. Based on the analysis and test, the optimum slot rate and length have been obtained. Experiments also show that the

Guobang Chen; Tao Sun; Jianyao Zheng; Zhixue Huang; Jianping Yu

1994-01-01

345

Multi-Shielded p-FET Dosimeter  

NASA Technical Reports Server (NTRS)

A compact device was developed for dose measurements where each of four p-FETs has a different shield. Radiation data from the STRV-1b shows that p-FETs can be used to map the radiation inside a spacecraft.

Buehler, M.; Blaes, B.; Martin, D.; Bowman, C.; Bogorad, A.

1995-01-01

346

The Tower Shielding Facility: Its glorious past  

SciTech Connect

The Tower Shielding Facility (TSF) is the only reactor facility in the US that was designed and built for radiation-shielding studies in which both the reactor source and shield samples could be raised into the air to allow measurements to be made without interference from ground scattering or other spurious effects. The TSF proved its usefulness as many different programs were successfully completed. It became active in work for the Defense Atomic Support Agency (DASA) Space Nuclear Auxiliary Power, Defense Nuclear Agency, Liquid Metal Fast Breeder Reactor Program, the Gas-Cooled and High-Temperature Gas-Cooled Reactor programs, and the Japanese-American Shielding Program of Experimental Research, just to mention a few of the more extensive ones. The history of the TSF as presented in this report describes the various experiments that were performed using the different reactors. The experiments are categorized as to the programs which they supported and placed in corresponding chapters. The experiments are described in modest detail, along with their purpose when appropriate. Discussion of the results is minimal, but references are given to more extensive topical reports.

Muckenthaler, F.J.

1997-05-07

347

FAST NEUTRON PENETRATION THROUGH REACTOR SHIELDS  

Microsoft Academic Search

Measurements of the penetration of reactor fast neutrons as a function ; of energy have been made in a thermal shield mock-up. The investigation was ; restricted to neutrons in the 2 to 10 Mev energy region A neutron energy ; spectrometer employing a Li⁶I(Eu) scintillation crystal was used. Relative ; spectral distributions are preserted for distances up to 12

N. Hartmann; G. R. Hopkins

1959-01-01

348

Electromagnetic interference shielding effectiveness of carbon materials  

Microsoft Academic Search

Carbon materials for electromagnetic interference (EMI) shielding are reviewed. They include composite materials, colloidal graphite and flexible graphite. Carbon filaments of submicron diameter are effective for use in composite materials, especially after electroplating with nickel. Flexible graphite is attractive for EMI gaskets.

D. D. L. Chung

2001-01-01

349

President Clinton Defers Missile Shield Decision  

NSDL National Science Digital Library

President Clinton will announce in a speech at Georgetown University today that he will not begin the initial steps to deploy a national missile defense shield, leaving the final decision to his successor. The decision to not begin construction of a radar site in Alaska, designed to track incoming missiles, was apparently the product of several factors. These include the failure of recent tests, strong opposition from Russia and some US allies, and fears that any decision would inevitably become politicized with the election nearing. Vice-President Al Gore has expressed conditional support for a missile shield, while George W. Bush has called for an even more extensive system. The President made his decision after receiving competing advice on the missile shield. William S. Cohen, the defense secretary, had recommended Mr. Clinton begin, while Samuel R. Berger, the President's national security advisor, and others recommended against construction at this point. Work on the project will continue nonetheless, including additional tests of the "kill vehicle" and a new booster rocket. The next President will decide not only whether to build the radar station and other elements of a missile shield infrastructure, but also whether to field the system and break the 1972 Antiballistic Missile Treaty.

de Nie, Michael Willem.

350

Oxygen Abundance Measurements of SHIELD Galaxies  

E-print Network

We have derived oxygen abundances for 8 galaxies from the Survey of HI in Extremely Low-mass Dwarfs (SHIELD). The SHIELD survey is an ongoing study of very low-mass galaxies, with M$_{\\rm HI}$ between 10$^{6.5}$ and 10$^{7.5}$ M$_{\\odot}$, that were detected by the Arecibo Legacy Fast ALFA (ALFALFA) survey. H$\\alpha$ images from the WIYN 3.5m telescope show that these 8 SHIELD galaxies each possess one or two active star-forming regions which were targeted with long-slit spectral observations using the Mayall 4m telescope at KPNO. We obtained a direct measurement of the electron temperature by detection of the weak [O III] $\\lambda$4363 line in 2 of the HII regions. Oxygen abundances for the other HII regions were estimated using a strong-line method. When the SHIELD galaxies are plotted on a B-band luminosity-metallicity diagram they appear to suggest a slightly shallower slope to the relationship than normally seen. However, that offset is systematically reduced when the near-infrared luminosity is used ins...

Haurberg, Nathalie C; Cannon, John M; Marshall, Melissa V

2015-01-01

351

PET/CT shielding design comparisons  

E-print Network

The objective of this project was to compare two different methods of calculating dose through lead-shielded walls in the PET/CT suite at Scott & White Hospital in Temple, Texas. The ultimate goal was to see which of the two methods agreed...

Coker, Audra Lee

2007-09-17

352

Review of active radiation shielding developments  

NASA Astrophysics Data System (ADS)

The radiation risk due to ionizing particles is a critical issue for long duration manned space missions. The ionization losses in the materials of the spacecraft provide passive shielding effectively stopping low energy particles. However, the estimates of the material required to obtain an acceptable level of radiation result in a prohibitive mass. Active electromagnetic shields, which deflect the charged particles, have been considered as an alternative solution. During the last 10 years the interest in this area has grown. A study of active magnetic shielding based on high-temperature superconductors (HTS) was initiated in an ESA study in 2010, continued in the context of the NASA Innovative Advanced Concepts (NIAC) programs (2011-2014) as well as within a dedicated FP7 EU program, SR2S (2013-2015). The aim of these effort was to provide a realistic evaluation of the possibilities based on current technology levels as well extrapolating to reasonable technology advances expected during the next decade. The different configurations considered were assessed in terms of their technical feasibility and shielding efficiency. We present here a status report of the ongoing work and some preliminary results.

Battiston, Roberto

353

Charge and Potential Distributions in Shielded Striplines  

Microsoft Academic Search

A new method is presented for calculating the charge and potential distribution in shielded microstrip lines with stratified dielectric fillings. The boundary value problem associated with this structure is formulated in a rigorous manner and the solution is constructed by an extension of the function-theoretic technique. Several advantages of this method are pointed out. The most important of these is

RAJ MITTRA; TATSUO ITOH

1970-01-01

354

SP100 reactor and shield design update  

Microsoft Academic Search

The SP-100 technical specification for the generic flight system has been updated to eliminate design specific and unnecessarily restrictive requirements. Relaxation of these requirements allows considerably more flexibility to the reactor and shield designer to minimize the mass of the system. Ground Engineering System (GES) Program test results are also beginning to become available to the designer. Some of these

Nelson A. Deane; Samuel L. Stewart; Thomas F. Marcille; Douglas W. Newkirk

1992-01-01

355

Logic circuitry used to automatically test shielded cables  

NASA Technical Reports Server (NTRS)

Automatic cable tester checks multiple shielded conductors assembly cable connections. The tester uses logic circuitry to sequentially test all conductors and their shields to reveal any connection error in a GO-NO GO test.

Dibb, G.

1966-01-01

356

Early test facilities and analytic methods for radiation shielding: Proceedings  

SciTech Connect

This report represents a compilation of eight papers presented at the 1992 American Nuclear Society/European Nuclear Society International Meeting. The meeting is of special significance since it commemorates the fiftieth anniversary of the first controlled nuclear chain reaction. The papers contained in this report were presented in a special session organized by the Radiation Protection and Shielding Division in keeping with the historical theme of the meeting. The paper titles are good indicators of their content and are: (1) The origin of radiation shielding research: The Oak Ridge experience, (2) Shielding research at the hanford site, (3) Aircraft shielding experiments at General Dynamics Fort Worth, 1950-1962, (4) Where have the neutrons gone , a history of the tower shielding facility, (5) History and evolution of buildup factors, (6) Early shielding research at Bettis atomic power laboratory, (7) UK reactor shielding: then and now, (8) A very personal view of the development of radiation shielding theory.

Ingersoll, D.T. (comp.) (Oak Ridge National Lab., TN (United States)); Ingersoll, J.K. (comp.) (Tec-Com, Knoxville, TN (United States))

1992-11-01

357

Benchmark experiments for space Reactor neutron shielding of mission electronics  

Microsoft Academic Search

Experiments and calculations simulating the neutron shadow shield for a reactor-powered space vehicle are described, including calculations for a variety of shield configurations and materials, and an experimental benchmark test using a bare fast reactor.

John G. Williams; Insoo Jun; Wesley W. Sallee; Michael Cherng

2004-01-01

358

Fusion for Earth and Space  

NASA Astrophysics Data System (ADS)

The compact reactor concept (Williams, 2007) has the potential to provide clean, safe and unlimited supply of energy for Earth and Space applications. The concept is a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for individual home and space power. The concept also would make it possible for each plant or remote location to have it's own power source, on site, without the need for a connection to the power grid. This would minimize, or eliminate, power blackouts. The concept could replace large fission reactors and fossil fuel power plants plus provide energy for ships, locomotives, trucks and autos. It would make an ideal source of energy for space power applications and for space propulsion.

Williams, Pharis E.

2009-03-01

359

Shielding consideration for the SSCL experimental halls  

SciTech Connect

The Superconducting Super Collider which is being designed and built in Waxahachie, Texas consists Of series of proton accelerators, culminating in a 20 Te proton on proton collider. The collider will be in a tunnel which will be 87 km in circumference and. on average about 30 meters underground. The present design calls for two large interaction halls on the east side of the ring. The shielding for these halls is being designed for an interaction rate of 10{sup 9} Hz or 10{sup 16} interactions per year, based on 10{sup 7} seconds per operational year. SSC guidelines require that the shielding be designed to meet the criterion of 1mSv per year for open areas off site 2mSv per year for open areas on site, and 2mSv per year for controlled areas. Only radiation workers will be routinely allowed to work in controlled areas. It should be pointed that there is a potential for an accidental full beam loss in either of the experimental halls, and this event would consist of the loss of the full circulating beam up to 4 {times} 10{sup 14} protons. With the present design. the calculated dose equivalent for this event is about 10% of the annual dose equivalent for the normal p-p interactions, so that die accident condition does not control the shielding. If, for instance, local shielding within the experimental hall is introduced into the calculations, this could change. The shielding requirements presented here are controlled by the normal p-p interactions. Three important questions were addressed in the present calculations. They are (1) the thickness of the roof over the experimental halls, (2) the configuration of the shafts and adits which give access to the halls, and (3) the problem of ground water and air activation.

Bull, J.; Coyne, J.; Mokhov, N.; Stapleton, G.

1994-03-01

360

Computer subroutines for estimation of human exposure to radiation in low Earth orbit  

NASA Technical Reports Server (NTRS)

Computer subroutines to calculate human exposure to trapped radiations in low Earth orbit (LEO) on the basis of a simple approximation of the human geometry by spherical shell shields of varying thickness are presented and detailed. The subroutines calculate the dose to critical body organs and the fraction of exposure limit reached as a function of altitude of orbit, degree of inclination, shield thickness, and days in mission. Exposure rates are compared with current exposure limits.

Cucinotta, F. A.; Wilson, J. W.

1985-01-01

361

Designing dual-plate meteoroid shields: A new analysis  

NASA Technical Reports Server (NTRS)

Physics governing ultrahigh velocity impacts onto dual-plate meteor armor is discussed. Meteoroid shield design methodologies are considered: failure mechanisms, qualitative features of effective meteoroid shield designs, evaluating/processing meteoroid threat models, and quantitative techniques for optimizing effective meteoroid shield designs. Related investigations are included: use of Kevlar cloth/epoxy panels in meteoroid shields for the Halley's Comet intercept vehicle, mirror exposure dynamics, and evaluation of ion fields produced around the Halley Intercept Mission vehicle by meteoroid impacts.

Swift, H. F.; Bamford, R.; Chen, R.

1982-01-01

362

The design of asymmetric 4 pi shields for space reactors  

NASA Technical Reports Server (NTRS)

A one dimensional shield optimization program based on the method of discrete ordinates has been developed and is used to determine material thicknesses used in asymmetric 4 pion shields for space power reactors. The two dimensional discrete ordinates program DOT is used to check the design, and the information generated in the DOT calculation is used as a guide in shaping the shield which may be considered a first step in two dimensional shield optimization.

Engle, W. W., Jr.; Childs, R. L.; Mynatt, F. R.

1972-01-01

363

A low-relief shield volcano origin for the South Kaua`i Swell  

NASA Astrophysics Data System (ADS)

The South Kaua`i Swell (SKS) is a 110 km x 80 km ovoid bathymetric feature that stands >2 km high and abuts the southern flank of the island of Kaua`i. The origin of the SKS was investigated using multibeam bathymetry and acoustic backscatter, gravity data, radiometric ages, and geochemistry of rock samples. Most of the SKS rock samples are tholeiitic in composition with ages of 3.9-5.4 Ma indicating they were derived from shield volcanism. The ages and compositions of the SKS rocks partially overlap with those of the nearby Ni`ihau, Kaua`i and West Ka`ena volcano complexes. The SKS was originally described as a landslide; however, this interpretation is problematic given the ovoid shape of SKS, its relatively smooth, flat-to-convex surface, and the lack of an obvious source region that could accommodate what would be one of Earth's most voluminous (6 x 103 km3) landslides. The morphology, size, and the surrounding gravity anomaly are more consistent with the SKS being a low-relief shield volcano, which was partially covered with a small volume of landside debris from south Kaua`i and later with some secondary volcanic seamounts. A shield origin would imply that Hawaiian and possibly other hotspot shield volcanoes can take on a wider variety of forms than is commonly thought, ranging from tall island-building shields, to smaller edifices such as Ka`ena Ridge and Mahukona, to even lower-relief volcanoes represented by the SKS and possibly the South West O`ahu Volcanic Field.

Ito, Garrett; Garcia, Michael O.; Smith, John R.; Taylor, Brian; Flinders, Ashton; Jicha, Brian; Yamasaki, Seiko; Weis, Dominique; Swinnard, Lisa; Blay, Chuck

2013-07-01

364

ALTEA-SHIELD: a survey of the radiation in the ISS (USLab)  

NASA Astrophysics Data System (ADS)

In general, radiation exposure represents one of the greatest risks to humans traveling on exploration missions beyond low Earth orbit (LEO). The ALTEA detector (ALTEA-Shield experiment) is used to measure the radiation environment in different places of the ISS-USLab. ALTEA-Shield is part of the ALTEA program, a multidisciplinary research project which aims at obtaining a better understanding of the radiation environment on board the International Space Station, and also at studying the interaction between cosmic rays and the astronauts visual system. The ALTEA-Shield/Survey experiment, financed by the Italian Space Agency (ASI) and sponsored by ESA, uses the six particle detectors (SDUs, Silicon Detector Units) of ALTEA arranged on a 3D isotropic support. It is capable to measure cosmic ray particles coming from three different directions, being able to give an overview on the particle fluxes (in a detectable energy range between 3 and 900 keV/um) in different locations of the USLab. The ALTEA-Shield/Survey experiment started on September 2010 and it was placed in four locations of the USLab, resulting in a total observation time of more than 290 days. We present here the particle fluxes in the four positions, together with previous measurements acquired under the ALTEA-DOSI experimental sessions in 2006-2009; ALTEA is able to discriminate ion species (charge Z) from Z>4 and to measure the trajectory of each particle, so to be able to reconstruct the radiation flux in the three direction XYZ. The differences in the flux measured along these directions (along the ISS main body and two transverse directions) are mostly due to the different amount and quality of shielding materials passed by the incoming nuclei.

Zaconte, Veronica; Di Fino, Luca; Larosa, Marianna; Picozza, Piergiorgio; Narici, Livio; Casolino, Marco

2012-07-01

365

Beam test of the BGO anticoincidence shield for IBIS on INTEGRAL  

NASA Astrophysics Data System (ADS)

A Bismuth Germanate (BGO) 'veto' shield surrounds on five faces the detector planes of the IBIS instrument on-board the satellite INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory). The Veto System provides anti-coincidence signals to the two imager layers covering the energy range from 20 keV to 10 MeV. The area to be shielded is about 8000 cm2, and with a shield thickness of 20 mm, this leads to a total BGO crystal weight of about 115 kg. This paper describes the shield design, and how some scientific and engineering requirements are implemented. Also results from tests with the Engineering Model are presented. Particular emphasis is given to the electronic signal chain, and its response to overload particles, mainly high energy protons, expected in the INTEGRAL orbit (Elliptic Earth Orbit with 72 h period). The overload response has been studied in detail both with a built-in Light Emitting Diode (LED) in the laboratory, and at a proton beam facility. Based on the lab measurements the expected blinding of the shield in-orbit is around 1%. This is obtained with a simple, but optimized chain, consisting of a front-end amplifier and a bi-polar shaper, that provides input to the trigger generator. Results from beam tests with proton energies from 60 to 300 MeV are reported, and it is demonstrated that the proton pulses in terms of amplitude, shape and duration are very similar to the simulated ones, and thus confirm the expected system response.

Poulsen, Jens M.; Sarra, Paolo F.; Hajdas, W.; Ubertini, Pietro; Quadrini, E. M.; Orleanski, Piotr; Bronstad, Kjell; Bird, Antony J.; De Cesare, Giampiero; Solberg, Arne O.; Bastia, P.

2000-12-01

366

A lightweight debris shield using high strength fibers  

Microsoft Academic Search

The purpose of this study was to develop a new lightweight shield using high strength fibers against hypervelocity impacts from space debris (in particular, 1 to 10 cm in diameter). We developed the new lightweight shield using Vectran fibers. The experimental results showed that the developed shield could stop the polycarbonate projectile with 14 mm in diameter, 1 gram in

Yoko Moritaka; Yoko Ogawa; Makoto Tanaka; Yasuhiro Akahoshi; Ryuta Nakamura; Daigo Watanabe; Akira Yamori; Susumu Sasaki

2001-01-01

367

Ballistic limit evaluation of advanced shielding using numerical simulations  

Microsoft Academic Search

The advanced shielding concept employed for the Columbus module of the International Space Station consists of an aluminum bumper and an intermediate shield of Nextel and Kevlar-epoxy. Until recently, the lack of adequate material models for the Nextel cloth and Kevlar-epoxy has precluded the practical usage of hydrocodes in evaluating the response of these shields to hypervelocity impact threats. Recently

Colin J. Hayhurst; Iain H. G. Livingstone; Richard A. Clegg; Roberto Destefanis; Moreno Faraud

2001-01-01

368

A radiation-shielding device for craniofacial implant placement  

Microsoft Academic Search

The use of radiation shields in the head and neck cancer patient receiving adjuvant radiation therapy is a treatment alternative for protecting anticipated prosthetic implant sites. Shields can be fabricated easily as part of an interdisciplinary treatment protocol. In this article, the methods used to fabricate an extraoral radiation shield are described, and a patient treatment that illustrates possible uses

Regina B. Hatfield; V. Vladimir Frias; Jack J. Wazen; Steven R. Isaacson; Eric S. Asher; Robert F. Wright

2001-01-01

369

PLASMA RADIATION SHIELD: CONCEPT AND APPLICATIONS TO SPACE VEHICLES  

Microsoft Academic Search

The plasma radiation shield is an active device using free electrons, electric and magnetic fields for the purpose of shielding astronauts from energetic solar flare-produced protons. The concept of plasma radiation shielding is reviewed in the light of current studies. The available evidence indicates that the concept is physically sound, but important practical questions remain in at least two areas;

RICHARD H. LEVY; FRANCIS W. FRENCH

1968-01-01

370

Space Radiation Shielding Program http://radiationshielding.nasa.gov  

E-print Network

Space Radiation Shielding Program http://radiationshielding.nasa.gov #12;Multi-Functional Material Physical Modeling #12;Space Radiation Shielding Program Radiation Transport Codes Cross Section of radiation shielding materials for spacecraft, habitat, and space suits ­ Testing and maturation of new

Shepherd, Simon

371

Electromagnetic Interference (EMI) Shielding of Single-Walled Carbon  

E-print Network

Electromagnetic Interference (EMI) Shielding of Single-Walled Carbon Nanotube Epoxy Composites Ning (SWNT)-polymer composites have been fabricated to evaluate the electromagnetic interference (EMI EMI shielding materials. Composites with greater than 20 dB shielding efficiency were obtained easily

Gao, Hongjun

372

Radiation shielding for underground low-background experiments  

Microsoft Academic Search

The design task of creating an efficient radiation shield for the new COBRA double-beta decay experiment led to a comprehensive study of commercially available shielding materials. The aim was to find the most efficient combination of materials under the constraints of an extreme low-background experiment operating in a typical underground laboratory. All existing shield configurations for this type of experiment

D. Y. Stewart; P. F. Harrison; B. Morgan; Y. Ramachers

2007-01-01

373

Radiation shielding for underground low-background experiments  

Microsoft Academic Search

The design task of creating an efficient radiation shield for the new COBRA double-beta decay experiment led to a comprehensive study of commercially available shielding materials. The aim was to find the most efficient combination of materials under the constraints of an extreme low-background experiment operating in a typical underground laboratory. All existing shield configurations for this type of experiment

D. Y. Stewart; P. F. Harrison; B. Morgan; Y. A. Ramachers

2006-01-01

374

Dose buildup factor formula for double-layered shields  

Microsoft Academic Search

In radiation shielding, health physics, and radioactive waste management, it is very important to know buildup factors for various materials and their combinations used as multilayer shields. In this work, a general formula that computes buildup factors for double-layer shields was developed on the basis of Monte Carlo photon transport using the MCNP code. Formulas for buildup factors for double-layer

M. Guvendik; N. Tsoulfanidis

1999-01-01

375

Packed rod neutron shield for fast nuclear reactors  

Microsoft Academic Search

A fast neutron nuclear reactor including a core and a plurality of vertically oriented neutron shield assemblies surrounding the core. Each assembly includes closely packed cylindrical rods within a polygonal metallic duct. The shield assemblies are less susceptible to thermal stresses and are less massive than solid shield assemblies, and are cooled by liquid coolant flow through interstices among the

John E. Eck; Alvin H. Kasberg

1978-01-01

376

Packed rod neutron shield for fast nuclear reactors  

Microsoft Academic Search

A fast neutron nuclear reactor including a core and a plurality of vertically oriented neutron shield assemblies surrounding the core is disclosed. Each assembly includes closely packed cylindrical rods within a polygonal metallic duct. The shield assemblies are less susceptible to thermal stresses and are less massive than solid shield assemblies, and are cooled by liquid coolant flow through interstices

J. E. Eck; A. H. Kasberg

1978-01-01

377

Fast neutron penetration through an axially-symmetrical shield  

Microsoft Academic Search

The shield is broken up into arbitrary layers with twofold attenuation ; of neutrons and with corresponding equalization of the neutron attenuation over ; the shield depth. This procedure was programmed on a computer for shielding ; computations. From this program it is possible to calculate integral fluxes of ; neutrons with energies of 0.1 to 14 MeV both within

A. N. Kozhevnikov; V. A. Khodakov; A. V. Khrustalev

1973-01-01

378

SHIELDING ASTRONAUTS FROM COSMIC RAYS E. N. Parker  

E-print Network

1 SHIELDING ASTRONAUTS FROM COSMIC RAYS E. N. Parker Dept. of Physics and Dept. of Astronomy shielding of an astronaut by surrounding mass involves too much total mass to be practical for launching into space. Magnetic shielding requires transverse field of about 107 Gauss cm (to deflect particles up to 2

Shepherd, Simon

379

Engineering of Ferrite-Graphite Composite Media for Microwave Shields  

E-print Network

Engineering of Ferrite-Graphite Composite Media for Microwave Shields Marina Koledintseva, PoornaAA@mpei.ru Abstract-- An electromagnetic shielding of objects using ferrite-graphite composites is considered- shielding; dielectric base material; ferrite- graphite composite, Maxwell Garnett formulation I

Koledintseva, Marina Y.

380

Application of Modal Analysis to Braided-Shield Cables  

Microsoft Academic Search

Transmission-line equations are derived for a braidedshield cable by modal analysis. The parameters of the braided shield appear in the coefficients as well as in the source terms of the equations. The source terms also depend on the currents and charges on the outer surface of the shield with all the shield's apertures shortcircuited.

K. S. H. Lee; CARL E. BAUM

1975-01-01

381

Refractory metal shielding /insulation/ increases operating range of induction furnace  

NASA Technical Reports Server (NTRS)

Thermal radiation shield contains escaping heat from an induction furnace. The shield consists of a sheet of refractory metal foil and a loosely packed mat of refractory metal fibers in a concentric pattern. This shielding technique can be used for high temperature ovens, high temperature fluid lines, and chemical reaction vessels.

Ebihara, B. T.

1965-01-01

382

DARHT : integration of shielding design and analysis with facility design  

Microsoft Academic Search

The design of the interior portions of the Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility incorporated shielding and controls from the beginning of the installation of the Accelerators. The purpose of the design and analysis was to demonstrate the adequacy of shielding or to determine the need for additional shielding or controls. Two classes of events were considered: (1) routine

R. L. Boudrie; T. H. Brown; W. E. Gilmore; Downing J. N. Jr; Alan Hack; D. A. McClure; C. A. Nelson; E. Alan Wadlinger; M. V. Zumbro

2002-01-01

383

Earth 911  

NSDL National Science Digital Library

Earth 911 is an organization focused on empowering the public with community-specific resources to improve their quality of life. To accomplish this goal, they provide information on a wide range of environmental topics including recycling (several types of materials), household hazardous waste, water quality, composting, air pollution prevention, fire prevention, green shopping tips, and mercury pollution. Environmental news links, games and activities for kids, and local news and events are also included. Users may enter a zip code to obtain information on environmental issues specific to where they live.

2004-01-01

384

How stable are the 'stable ancient shields'?  

NASA Astrophysics Data System (ADS)

"Archean cratons are relatively flat, stable regions of the crust that have remained undeformed since the Precambrian, forming the ancient cores of the continents" (King, EPSL, 2005). While this type of statement is supported by a wealth of constraints in the case of episodes of thoroughgoing ductile deformation affecting shield regions of Archean and also Peleoproterozoic age, a growing amount of research indicates that shields are not nearly as structurally stable within the broad field of environmental conditions leading to brittle deformation. In fact, old crystalline basements usually present compelling evidence of long brittle deformation histories, often very complex and challenging to unfold. Recent structural and geochronological studies point to a significant mechanical instability of the shield areas, wherein large volumes of 'stable' rocks actually can become saturated with fractures and brittle faults soon after regional cooling exhumes them to below c. 300-350° C. How cold, rigid and therefore strong shields respond to applied stresses remains, however, still poorly investigated and understood. This in turn precludes a better definition of the shallow rheological properties of large, old crystalline blocks. In particular, we do not yet have good constraints on the mechanisms of mechanical reactivation that control the partial (if not total) accommodation of new deformational episodes by preexisting structures, which remains a key to untangle brittle histories lasting several hundred Myr. In our analysis, we use the Svecofennian Shield (SS) as an example of a supposedly 'stable' region with Archean nucleii and Paleoproterozoic cratonic areas to show how it is possible to unravel the details of brittle histories spanning more than 1.5 Gyr. New structural and geochronological results from Finland are integrated with a review of existing data from Sweden to explore how the effects of far-field stresses are partitioned within a shield, which was growing progressively saturated with fractures as time passed from its initial consolidation. The comparison of time-constrained paleostress data derived from three different locations of the shield shows a remarkably similar stress evolution through time, despite the different geological frameworks of the investigated areas. This suggests that the southern SS has behaved as a coherent rigid crustal block since the Late Mesoproterozoic. By that time, the SS had already reached structural maturity with respect to the saturation of brittle structural features. Therefore, structural reactivation rather than generation of new faults and fractures is the key mechanism that has controlled the mechanical evolution of the shield and that will steer its future evolution within the brittle regime. Comparable brittle structural histories within parts of the shield that are far apart also imply that far-field stresses can propagate over large distances and can lead to similar deformational histories, with the local geological conditions only playing a second-order role on the final brittle strain pattern recorded by the rock.

Viola, Giulio; Mattila, Jussi

2014-05-01

385

region between x-rays and visible light, can be observed only by sensors above the Earth's  

E-print Network

was started on concepts for shielding the Starprobe spacecraft from heating during the close flyby when solar radiation will be 3000 times more intense than sunlight at Earth. Planetology Program The Viking Lander to an active geothermal area on Earth such as Yellowstone. The data imply that 10 has a partially molten

Waliser, Duane E.

386

Solar wind induced magnetic field around the unmagnetized Earth  

E-print Network

The Earth is a planet with a dipolar magnetic field which is agitated by a magnetized plasma wind streaming from the Sun. The magnetic field shields the Earth's surface from penetrating high energy solar wind particles, as well as interstellar cosmic rays. The magnetic dipole has reversed sign some hundreds of times over the last 400 million years. These polarity reversals correspond to drastic breakdowns of the dynamo action. The question arises what the consequences for the Earth's atmosphere, climate, and, in particular, biosphere are. It is shown by kinematic estimates and three-dimensional plasma-neutral gas simulations that the solar wind can induce very fast a magnetic field in the previously completely unmagnetized Earth's ionosphere that is strong enough to protect Earth from cosmic radiations comparable to the case of an intact magnetic dynamo.

G. T. Birk; H. Lesch; C. Konz

2004-04-29

387

Shielding, Levitation, Propulsion G. W. Jewell, Chariman Method for expanding the uniformly shielded area in a short-length  

E-print Network

of supercon- ducting quantum interference device SQUID gradiometers if its axial shielding factor is increased allows the construction of rela- tively compact, lightweight, open-ended cylindrical magnetic shields shields employing magnetic shaking are relatively compact, available space does not al- ways allow

Paperno, Eugene

388

GOOGLE EARTH QUICK GUIDE (1)Google Earth Features  

E-print Network

GOOGLE EARTH QUICK GUIDE (1)Google Earth Features The Google Earth of the Google Earth window. Often when opening up the Google Earth program, the view screen will be a view of the entire Earth from space. Navigation bar

Smith-Konter, Bridget

389

Design and Development of an In-Space Deployable Sun Shield for the Atlas Centaur  

NASA Technical Reports Server (NTRS)

The Centaur, by virtue of its use of high specific-impulse (Isp) LO2/LH2 propellants, has initial mass-to-orbit launch requirements less than half of those upper stages using storable propellants. That is, for Earth escape or GSO missions the Centaur is half the launch weight of a storable propellant upper stage. A drawback to the use of Liquid oxygen and liquid hydrogen, at 90 K and 20 K respectively, over storable propellants is the necessity of efficient cryogen storage techniques that minimize boil-off from thermal radiation in space. Thermal blankets have been used successfully to shield both the Atlas Centaur and Titan Centaur. These blankets are protected from atmospheric air loads during launch by virtue of the fact that the Centaur is enclosed within the payload fairing. The smaller Atlas V vehicle, the Atlas 400, has the Centaur exposed to the atmosphere during launch, and therefore, to date has not flown with thermal blankets shielding the Centaur. A design and development effort is underway to fly a thermal shield on the Atlas V 400 vehicle that is not put in place until after the payload fairing jettisons. This can be accomplished by the use of an inflatable and deployable thermal blanket referred to as the Centaur Sun Shield (CSS). The CSS design is also scalable for use on a Delta upper stage, and the technology potentially could be used for telescope shades, re-entry shields, solar sails and propellant depots. A Phase I effort took place during 2007 in a partnership between ULA and ILC Dover which resulted in a deployable proof-of-concept Sun Shield being demonstrated at a test facility in Denver. A Phase H effort is underway during 2008 with a partnership between ULA, ILC, NASA Glenn Research Center (GRC) and NASA Kennedy Space Center (KSC) to define requirements, determine materials and fabrication techniques, and to test components in a vacuum chamber at cold temperatures. This paper describes the Sun Shield development work to date, and the future plans leading up to a flight test in the 2011 time frame.

Dew, Michael; Allwein, Kirk; Kutter, Bernard; Ware, Joanne; Lin, John; Madlangbayan, Albert; Willey, Cliff; Pitchford, Brian; O'Neil, Gary

2008-01-01

390

Potential Polymeric Sphere Construction Materials for a Spacecraft Electrostatic Shield  

NASA Technical Reports Server (NTRS)

An electrostatic shielding concept for spacecraft radiation protection under NASA s Exploration Systems Research and Technology Program was evaluated for its effectiveness and feasibility. The proposed shield design is reminiscent of a classic quadrupole with positively and negatively charged spheres surrounding the spacecraft. The project addressed materials, shield configuration, power supply, and compared its effectiveness to that of a passive shield. The report herein concerns the identification of commercially available materials that could be used in sphere fabrication. It was found that several materials were needed to potentially construct the spheres for an electrostatic shield operating at 300 MV.

Smith, Joseph G., Jr.; Smith, Trent; Williams, Martha; Youngquist, Robert; Mendell, Wendell

2006-01-01

391

Passive Superconducting Shielding: Experimental Results and Computer Models  

NASA Technical Reports Server (NTRS)

Passive superconducting shielding for magnetic refrigerators has advantages over active shielding and passive ferromagnetic shielding in that it is lightweight and easy to construct. However, it is not as easy to model and does not fail gracefully. Failure of a passive superconducting shield may lead to persistent flux and persistent currents. Unfortunately, modeling software for superconducting materials is not as easily available as is software for simple coils or for ferromagnetic materials. This paper will discuss ways of using available software to model passive superconducting shielding.

Warner, B. A.; Kamiya, K.

2003-01-01

392

Volcano Flank Structures on Earth and Mars  

NASA Astrophysics Data System (ADS)

Shield volcanoes on Earth and Mars share common features, including calderas and pit crater chains. A set of structures present on the sides of several of the large shields on Mars are not regarded as having Earth analogues, however. Flank terraces are topographically subtle structures, characterised by a gentle convex profile and a distinctive "fish scale" imbricate distribution pattern. Magma chamber inflation, lithospheric flexure, flank relaxation, or gravitational slumping have been suggested as terrace formation mechanisms. Terraces on both Mars and Earth are clearly visible only in slope maps, and may thus escape visual detection in the field. We show that both Mauna Loa (Hawaii) and Etna (Sicily) display the same characteristic "fish scale" terrace pattern. This pattern delineates structures that we contend are terrestrial flank terraces. Heterogeneities in volcano geometry, due to buttressing or extension, result in terrace distributions that are not as evenly circumferential as those on Mars. Plan and cross-sectional profiles, however, parallel those of the Martian structures. These structures may also be present on Alayta (Ethiopia), Santa Cruz (Galapagos), and Tendürek Dagi (Turkey). Another type of structure, larger and steeper than flank terraces but sharing a similar plan-view morphology, is also present on Mauna Lau and Etna. These "flank bulges" appear to correlate with structures on Piton de la Fournaise (La Réunion), Cosiguina (Nicaragua), and Karthala (Comoros) on Earth, and Apollinaris Patera and Tharsis Tholus on Mars. Elsewhere (Paul K. Byrne et al., this volume) we argue that lithospheric flexure is a likely formation mechanism for Martian terraces. Flexure is active beneath Mauna Loa, and possibly under Etna, and so may also be responsible for terrestrial flank terraces. Scaled analogue models suggest that the larger flank bulges are due to magma intrusions derived from large chambers within these edifices. There is thus a strong morphological link between deformation, intrusion, and surface topography. Additionally, as these structures occur on both planets, the governing tectonic and volcanological processes are fundamentally the same for Earth and Mars.

van Wyk de Vries, B.; Byrne, P. K.; Mathieu, L.; Murray, J. B.; Troll, V. R.

2007-12-01

393

The early faint sun paradox: organic shielding of ultraviolet-labile greenhouse gases  

NASA Technical Reports Server (NTRS)

Atmospheric mixing ratios of approximately 10(-5 +/- 1) for ammonia on the early Earth would have been sufficient, through the resulting greenhouse warming, to counteract the temperature effects of the faint early sun. One argument against such model atmospheres has been the short time scale for ammonia photodissociation by solar ultraviolet light. Here it is shown that ultraviolet absorption by steady-state amounts of high-altitude organic solids produced from methane photolysis may have shielded ammonia sufficiently that ammonia resupply rates were able to maintain surface temperatures above freezing.

Sagan, C.; Chyba, C.

1997-01-01

394

Supplemental heating of deposition tooling shields  

DOEpatents

A method of reducing particle generation from the thin coating deposited on the internal surfaces of a deposition chamber which undergoes temperature variation greater than 100.degree. C. comprising maintaining the temperature variation of the internal surfaces low enough during the process cycle to keep thermal expansion stresses between the coating and the surfaces under 500 MPa. For titanium nitride deposited on stainless steel, this means keeping temperature variations under approximately 70.degree. C. in a chamber that may be heated to over 350.degree. C. during a typical processing operation. Preferably, a supplemental heater is mounted behind the upper shield and controlled by a temperature sensitive element which provides feedback control based on the temperature of the upper shield.

Ohlhausen, James A. (Albuquerque, NM); Peebles, Diane E. (Albuquerque, NM); Hunter, John A. (Albuquerque, NM); Eckelmeyer, Kenneth H. (Albuquerque, NM)

2000-01-01

395

Active Neutron Shielding for Dark Matter Searches  

NASA Astrophysics Data System (ADS)

Neutrons are a dangerous background to direct dark matter detection searches because they can mimic exactly the signal signature. Recent studies find that the few existing underground measurements of the fast, muon-induced neutron flux disagree at the 30%-50% level with predictions. Given this level of uncertainty, it is desirable to measure the neutron flux in-situ, as well as to reduce the number of neutrons incident on a dark matter detector. Towards these ends, we are developing a neutron veto system for both active and passive shielding. The goals of this R&D are (i) a measurement of the neutron energy spectrum underground above 10 MeV neutron kinetic energies, and (ii) measurements of the attenuation vs. energy of these neutrons in 1 meter of water, concrete, and liquid scintillator. These measurements will provide valuable input for simulation and design of shields for low-background experiments underground.

Monroe, Jocelyn; Yamamoto, Richard; Fisher, Peter; Cornell, Brett; Robinson, Mareena; Cowern, Dianna; Eyers, Richard; Henderson, Shawn

2009-05-01

396

Debye shielding in a nonextensive plasma  

SciTech Connect

The phenomenon of Debye Shielding is revisited within the theoretical framework of the Tsallis statistical mechanics. The plasma consists of nonextensive electrons and ions. Both the effective Debye length {lambda}{sub D}{sup q} and the fall-off of the electrostatic potential {Phi} are considered and a parameter study conducted. Owing to electron nonextensivity, the critical Mach number derived from the modified Bohm sheath criterion may become less than unity allowing therefore ions with speed less than ion-acoustic speed to enter the sheath from the main body of the plasma. Considering the wide relevance of collective processes, our analysis may be viewed as a first step toward a more comprehensive Debye shielding and electrostatic plasma sheath in nonequilibrium plasmas.

Ait Gougam, Leila; Tribeche, Mouloud [Faculty of Sciences-Physics, Theoretical Physics Laboratory (TPL), University of Bab-Ezzouar, U.S.T.H.B, B.P. 32, El Alia, Algiers 16111 (Algeria)

2011-06-15

397

Electronically shielded solid state charged particle detector  

DOEpatents

An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite. 1 fig.

Balmer, D.K.; Haverty, T.W.; Nordin, C.W.; Tyree, W.H.

1996-08-20

398

Electronically shielded solid state charged particle detector  

DOEpatents

An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite.

Balmer, David K. (155 Coral Way, Broomfield, CO 80020); Haverty, Thomas W. (1173 Logan, Northglenn, CO 80233); Nordin, Carl W. (7203 W. 32nd Ave., Wheatridge, CO 80033); Tyree, William H. (1977 Senda Rocosa, Boulder, CO 80303)

1996-08-20

399

Radiation shielding of concretes containing different aggregates  

Microsoft Academic Search

The shielding of ?-rays by concrete has been investigated for concretes containing different amounts of barite and normal weight aggregates. The linear attenuation coefficients (?, cm?1) have been calculated at photon energies of 1keV to 100GeV using XCOM and the obtained results compared with the measurements at the photon energies of 0.66MeV and 1.33MeV. It is shown that the type

I. Akkurt; C. Basyigit; S. Kilincarslan; B. Mavi; A. Akkurt

2006-01-01

400

Target Magnets & Shielding Particle Beam Lasers, Inc.  

E-print Network

Engineering, LLC. March 5, 2012 1 #12;Isometric View of Three TargetMagnet Designs Design IDS120h (top), IDS; Outer 30 tons/m; Inner 8 tons/m. 4 #12;Isometric View of Meshed Shielding Vessels of IDS120h 5 #12;Sag /B Desired fieldTotal field SC magnet Resistive magnet Distance along axis [cm] On-axisfield[T] 10

McDonald, Kirk

401

Hypervelocity impact simulations of Whipple shields  

NASA Technical Reports Server (NTRS)

The problem associated with protecting space vehicles from space debris impact is described. Numerical simulation is espoused as a useful complement to experimentation: as a means to help understand and describe the hypervelocity impact phenomena. The capabilities of a PC-based hydrocode, ZeuS, are described, for application to the problem of hypervelocity impact. Finally, results of ZeuS simulations, as applied to the problem of bumper shield impact, are presented and compared with experimental results.

Segletes, Steven B.; Zukas, Jonas A.

1992-01-01

402

New Electromagnetic Interference Shielding Material Demonstrated  

NASA Technical Reports Server (NTRS)

A demonstration electromagnetic interference (EMI) shielding cover that has a potential mass savings in excess of 80 percent over conventional aluminum has been fabricated and tested. It was the culmination of a 3-yr effort involving Hughes Space and Communications (Los Angeles), Applied Sciences, Inc. (Cedarville, Ohio), and the NASA Lewis Research Center. The cover was fabricated from a composite of polycyanate ester resin and graphite fibers that had been chemically modified by intercalation to enhance their electrical conductivity.

Gaier, James R.

1997-01-01

403

Shielding analyses: the rabbit vs the turtle?  

SciTech Connect

This paper compares solutions using Monte Carlo and discrete- ordinates methods applied to two actual shielding situations in order to make some general observations concerning the efficiency and advantages/disadvantages of the two approaches. The discrete- ordinates solutions are performed using two-dimensional geometries, while the Monte Carlo approaches utilize three-dimensional geometries with both multigroup and point cross-section data.

Broadhead, B.L.

1996-12-31

404

SINBAD: Shielding integral benchmark archive and database  

SciTech Connect

SINBAD is a new electronic database developed to store a variety of radiation shielding benchmark data so that users can easily retrieve and incorporate the data into their calculations. SINBAD is an excellent data source for users who require the quality assurance necessary in developing cross-section libraries or radiation transport codes. The future needs of the scientific community are best served by the electronic database format of SINBAD and its user-friendly interface, combined with its data accuracy and integrity.

Hunter, H.T.; Ingersoll, D.T.; Roussin, R.W. [and others

1996-04-01

405

Linear nodal method for shielding applications  

Microsoft Academic Search

The linear nodal (LN) method for the discrete-ordinates form of the (X-Y) geometry transport equation has previously been described by Walters and O'Dell. The work described here develops new fixups to prevent the calculation of negative fluxes and compares the performance of the LN method and the weighted-difference methods available in DOT for several typical shielding problems. The LN method

R. L. Childs; W. A. Rhoades

1984-01-01

406

SQUID holder with high magnetic shielding  

SciTech Connect

We discuss a SQUID holder designed for high magnetic shielding. We show how to estimate the attenuation of the magnetic field from the normal magnetic modes for an approximate geometry. The estimate agrees satisfactorily with the attenuation measured with a commercial rf SQUID installed in the holder. The holder attenuates external magnetic fields by more than 10{sup 9} at the SQUID input. With the SQUID input shorted, the response to external fields is 10{sup {minus}5} {Phi}{sub 0}/G.

Rigby, K.W.; Marek, D.; Chui, T.C.P. (Department of Physics, Stanford University, Stanford, California 94305 (US))

1990-02-01

407

SQUID holder with high magnetic shielding  

NASA Technical Reports Server (NTRS)

A SQUID holder designed for high magnetic shielding is discussed. It is shown how to estimate the attenuation of the magnetic field from the normal magnetic modes for an approximate geometry. The estimate agrees satisfactorily with the attenuation measured with a commercial RF SQUID installed in the holder. The holder attenuates external magnetic fields by more than 10 to the 9th at the SQUID input. With the SQUID input shorted, the response to external fields is 0.00001 Phi(0)/G.

Rigby, K. W.; Marek, D.; Chui, T. C. P.

1990-01-01

408

Earth Pulse  

NSDL National Science Digital Library

Earth Pulse is the National Geographic site for conservation. It features a set of links to National Geographic sites with a variety of conservation themes such as oceans, climate, energy, fresh water, and others. Many of these pages feature interactive tours or videos. Virtual Worlds is a set of interactive tours of various environments, from the rain forest at night to a new urbanist neighborhood. There is also a collection of Sights and Sounds interactive pages on a variety of ecosystems, in which users can click on a map and see information on wildlife that inhabits the selected region. There are also links to news articles and online expeditions in which users can follow actual expeditions as they were conducted by explorers-in-residence.

2007-12-12

409

Earth's Oceans  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. This guide focuses on the oceans as a part of the Earth system: the link between oceans and climate; tsunamis; life science concepts such as ocean ecosystems, food webs, and biodiversity; real data â both sources of and projects that use real data; and related careers. There is also a section on the misconceptions commonly surrounding ocean concepts and finally the National Science Education Standards that these resource connect to. So even though you might not teach a unit called oceans, the oceans can be used as a context within an existing unit, such as ecosystems, energy transfer, systems thinking, or methods in science.

Lightle, Kimberly; Fries-Gaither, Jessica

2009-10-01

410

Shielded silicon gate complementary MOS integrated circuit.  

NASA Technical Reports Server (NTRS)

An electrostatic shield for complementary MOS integrated circuits was developed to minimize the adverse effects of stray electric fields created by the potentials in the metal interconnections. The process is compatible with silicon gate technology. N-doped polycrystalline silicon was used for all the gates and the shield. The effectiveness of the shield was demonstrated by constructing a special field plate over certain transistors. The threshold voltages obtained on an oriented silicon substrate ranged from 1.5 to 3 V for either channel. Integrated inverters performed satisfactorily from 3 to 15 V, limited at the low end by the threshold voltages and at the high end by the drain breakdown voltage of the n-channel transistors. The stability of the new structure with an n-doped silicon gate as measured by the shift in C-V curve under 200 C plus or minus 20 V temperature-bias conditions was better than conventional aluminum gate or p-doped silicon gate devices, presumably due to the doping of gate oxide with phosphorous.

Lin, H. C.; Halsor, J. L.; Hayes, P. J.

1972-01-01

411

GRAVITATIONAL FIELD SHIELDING AND SUPERNOVA EXPLOSIONS  

SciTech Connect

A new mechanism for supernova explosions called gravitational field shielding is proposed, in accord with a five-dimensional fully covariant Kaluza-Klein theory with a scalar field that unifies the four-dimensional Einsteinian general relativity and Maxwellian electromagnetic theory. It is shown that a dense compact collapsing core of a star will suddenly turn off or completely shield its gravitational field when the core collapses to a critical density, which is inversely proportional to the square of mass of the core. As the core suddenly turns off its gravity, the extremely large pressure immediately stops the core collapse and pushes the mantle material of supernova moving outward. The work done by the pressure in the expansion can be the order of energy released in a supernova explosion. The gravity will resume and stop the core from a further expansion when the core density becomes less than the critical density. Therefore, the gravitational field shielding leads a supernova to impulsively explode and form a compact object such as a neutron star as a remnant. It works such that a compressed spring will shoot the oscillator out when the compressed force is suddenly removed.

Zhang, T. X. [Physics Department, Alabama A and M University, Normal, AL 35762 (United States)

2010-12-20

412

Topographic evidence for shield volcanism on Io  

SciTech Connect

Similarities between terrestrial shield volcanoes and a volcano on Io observed in Voyager I imagery of the satellite at 30/sup 0/ S, 246/sup 0/ W are delineated. A photoclinometry model was used to numerically estimate the slope based on the Minnaert photometric function. The slope values are accurate to within 10 deg on the sun-facing slope and 1 deg on the shadow side. As found with shield volcanoes, the feature has a central edifice, 40-50 km in diameter, and a broad, elliptical base, 77 x 90 km across. The summit of the Io volcano is 2.2-2.8 km above the surrounding plane and contains a caldera about 5 km in diameter. The similarity in shape between basaltic terrestrial shield volcanoes and the Io volcano indicates that the Io feature may also be composed of basalt. The composition could be sulfur if the heat flow was under 0.05 W/sq m, as it might have been in later stages of formation. 9 references.

Moore, J.M.; Mcewen, A.S.; Albin, E.F.; Greeley, R.

1986-07-01

413

Earth-Sun Geometry - Earth Revolution Animation  

NSDL National Science Digital Library

The representation is an animation of the Earth revolving around the sun. The Earth is shown as a solid green sphere with the equator and arctic circle marked with black lines and the dark side of the Earth shaded. The Earth's axis is shown with a red line. As the Earth revolves around the sun, the axis is shown to always be pointing in the same direction. The positions of Earth at the winter solstice, vernal equinox, summer solstice, and autumnal equinox are labeled.

Dr. Michael Pidwirny

414

Peculiarities of Spacecraft Photoelectron Shield Formation in Magnetic Field  

NASA Astrophysics Data System (ADS)

Traditionally, the current balance equations for a spacecraft in space plasma rely on the electric field of positively charged spacecraft. Equilibrium potential V is derived from currents outward and toward the spacecraft body. The currents are in turn functions of V. However, in reality photoelectrons move in both the electric field of the spacecraft and the Earth or the interplanetary magnetic field. This causes an anisotropic distribution of photoelectrons along a magnetic field line with the characteristic size of the order of several photoelectron gyro-radii. As a result, confinement of photoelectrons in the spacecraft-related electric field is much longer. Thus, a fraction of returned photoelectrons in the electron current toward the spacecraft can be rather great and may even dominate several times over the ambient electrons’ fraction. Modeled ph-electron trajectories as well as general photoelectron shield distribution around spacecraft are represented, and comparison of experimental data on the electron density with the magnetic flux tube model is discussed.

Veselov, Mikhail; Chugunin, Dmitriy

415

Effect on de-greasing solvents on conductive separable connector shields and semiconductive cable shields  

SciTech Connect

A study has been conducted to determine the effects of commercial degreasing solvents on the conductivity of an EPDM separable connector shield and two types of cable shields based on EPR and XLPE, respectively. Solvents tested included a chlorinated solvent based on 1,1,1-trichloroethane and several so-called citrus solvents consisting of the natural terpene, limonene, or blends of limonene with other hydrocarbons. All the solvents significantly degraded the conductivity of the EPR and EPDM materials, but had little effect on the XLPE cable shield. The solvents differed, however, in the extent of their effects, the rate of recovery of conductivity after removal of the solvent, and the degree to which the original conductivity of the material was restored. The consequences of these results in terms of appropriate field use of these types of solvents by utility personnel are discussed.

Perry, D.D.; Bolcar, J.P. (Amerace Corp., Hackettstown, NJ (USA). Elastimold Div.)

1990-04-01

416

Comparison of Martian Meteorites and Martian Regolith as Shield Materials for Galactic Cosmic Rays  

NASA Technical Reports Server (NTRS)

Theoretical calculations of radiation attenuation due to energetic galactic cosmic rays behind Martian rock and Martian regolith material have been made to compare their utilization as shields for advanced manned missions to Mars because the detailed chemical signature of Mars is distinctly different from Earth. The modified radiation fields behind the Martian rocks and the soil model were generated by solving the Boltzmann equation using a HZETRN system with the 1977 Solar Minimum environmental model. For the comparison of the attenuation characteristics, dose and dose equivalent are calculated for the five different subgroups of Martian rocks and the Martian regolith. The results indicate that changes in composition of subgroups of Martian rocks have negligible effects on the overall shielding properties because of the similarity of their constituents. The differences for dose and dose equivalent of these materials relative to those of Martian regolith are within 0.5 and 1 percent, respectively. Therefore, the analysis of Martian habitat construction options using in situ materials according to the Martian regolith model composition is reasonably accurate. Adding an epoxy to Martian regolith, which changes the major constituents of the material, enhances shielding properties because of the added hydrogenous constituents.

Kim, Myung-Hee Y.; Thibeault, Sheila A.; Simonsen, Lisa C.; Wilson, John W.

1998-01-01

417

Exploring Magnetism on Earth  

NSDL National Science Digital Library

This teacher's guide contains four lessons that provide a way for teachers to introduce students to and elaborate on Earth's changing magnetic field. It covers learning to navigate using Earth's magnetic field and compass, Earth's magnetic pole and its motion across Earth's surface, magnetic reversals on Earth, and Earth's currently declining magnetic field. These lessons have been taught primarily in math, geology, and astronomy classes.

2005-01-01

418

Analysis and improvement of cyclotron thallium target room shield.  

PubMed

Because of high neutron and gamma-ray intensities generated during bombardment of a thallium-203 target, a thallium target-room shield and different ways of improving it have been investigated. Leakage of neutron and gamma ray dose rates at various points behind the shield are calculated by simulating the transport of neutrons and photons using the Monte Carlo N Particle transport computer code. By considering target-room geometry, its associated shield and neutron and gamma ray source strengths and spectra, three designs for enhancing shield performance have been analysed: a shielding door at the maze entrance, covering maze walls with layers of some effective materials and adding a shadow-shield in the target room in front of the radiation source. Dose calculations were carried out separately for different materials and dimensions for all the shielding scenarios considered. The shadow-shield has been demonstrated to be one suitable for neutron and gamma dose equivalent reduction. A 7.5-cm thick polyethylene shadow-shield reduces both dose equivalent rate at maze entrance door and leakage from the shield by a factor of 3. PMID:18417490

Hajiloo, N; Raisali, G; Aslani, G

2008-01-01

419

Life on Earth. II The Hadean Earth  

E-print Network

Life on Earth. II #12;The Hadean Earth 4.5 - 3.9 Gyr Impacts melt the surface. Volatiles escape cools, rain replenished oceans Life appeared with 100 Myr of end of great bombardment Did life reform stabilized 3.9 Gya - 2.5 Gya #12;First Life What was the first life on Earth? ·The first living things must

Walter, Frederick M.

420

Academic Earth  

NSDL National Science Digital Library

Academic Earth provides videos of lectures by top scholars in "Subjects" that range from Astronomy to Entrepreneurship to Religion, from "Universities" as celebrated as MIT, Berkeley, Harvard, and Stanford. Visitors must register to view the lectures, but registration is free. There are over 1500 video lectures available, with more being added everyday. In addition to viewing the lectures available by subject or university, visitors can choose by "Instructors" or by "Playlists". When visitors click on "Playlists" at the top of the homepage, they will see a list of lectures by theme, by several different instructors, and a grade given to the lecture series. A good example is the 6-part lecture entitled "Understanding the Financial Crisis" by four different instructors. The series is given a grade overall, in this case, an A-, and when visitors click on "See all 6 lectures" at the bottom of the series' description, they will be taken to the page with the links to the individual lectures, as well as shown the grade given each individual lecture. Visitors can even keep a playlist of their favorite lectures or download the lectures. Visitors should definitely check out the Frequently Asked Questions page, accessible by the "FAQ" link at the bottom of the website.

421

Detecting the oldest geodynamo and attendant shielding from the solar wind: Implications for habitability  

NASA Astrophysics Data System (ADS)

The onset and nature of the earliest geomagnetic field is important for understanding the evolution of the core, atmosphere and life on Earth. A record of the early geodynamo is preserved in ancient silicate crystals containing minute magnetic inclusions. These data indicate the presence of a geodynamo during the Paleoarchean, between 3.4 and 3.45 billion years ago. While the magnetic field sheltered Earth’s atmosphere from erosion at this time, standoff of the solar wind was greatly reduced, and similar to that during modern extreme solar storms. These conditions suggest that intense radiation from the young Sun may have modified the atmosphere of the young Earth by promoting loss of volatiles, including water. Such effects would have been more pronounced if the field were absent or very weak prior to 3.45 billion years ago, as suggested by some models of lower mantle evolution. The frontier is thus trying to obtain geomagnetic field records that are ?3.45 billion-years-old, as well as constraining solar wind pressure for these times. In this review we suggest pathways for constraining these parameters and the attendant history of Earth’s deep interior, hydrosphere and atmosphere. In particular, we discuss new estimates for solar wind pressure for the first 700 million years of Earth history, the competing effects of magnetic shielding versus solar ion collection, and bounds on the detection level of a geodynamo imposed by the presence of external fields. We also discuss the prospects for constraining Hadean-Paleoarchean magnetic field strength using paleointensity analyses of zircons.

Tarduno, John A.; Blackman, Eric G.; Mamajek, Eric E.

2014-08-01

422

The low Earth orbit radiation environment and its impact on the prompt background of hard x-ray focusing telescopes  

NASA Astrophysics Data System (ADS)

The background minimization is a science-driven necessity in order to reach deep sensitivity levels in the hard X-ray band, one of the key scientific requirements for hard X-ray telescopes (e.g. NuSTAR, ASTRO-H). It requires a careful modeling of the radiation environment and new concepts of shielding systems. We exploit the Bologna Geant4 Multi-Mission Simulator (BoGEMMS) features to evaluate the impact of the Low Earth Orbit (LEO) radiation environment on the prompt background level for a hybrid Si/CdTe soft and hard X-ray detection assembly and a combined active and passive shielding system. For each class of particles, the spectral distribution of the background flux is simulated, exploring the effect of different materials (plastic vs inorganic active scintillator) and configurations (passive absorbers enclosing or surrounded by the active shielding) on the background count rate. While protons are efficiently removed by the active shielding, an external passive shielding causes the albedo electrons and positrons to be the primary source of background. Albedo neutrons are instead weakly interactive with the active shielding, and they cause an intense background level below 10 keV via elastic scattering. The best shielding configuration in terms of background and active shielding count rates is given by an inorganic scintillator placed inside the passive layers, with the addition of passive material to absorb the intense fluorescence lines of the active shielding and avoid escape peaks on the CdTe detector.

Fioretti, V.; Bulgarelli, A.; Malaguti, G.; Bianchin, V.; Trifoglio, M.; Gianotti, F.

2012-07-01

423

Tectonic and volcanic features of Mars as compared to earth  

Microsoft Academic Search

Volcano-tectonic activity on Mars is discussed and compared with the same type of activity on earth. Attention is given to Martian impact craters, a proposed chronological sequence for the great Tharsis uplift, evidence for a dense water-laden atmosphere over Mars during the early history of the planet, the fissure-fed lava plains and shield volcanoes of Mars, forms of tectonic activity

P. Mohr

1978-01-01

424

Radiation shielding for future space exploration missions  

NASA Astrophysics Data System (ADS)

Scope and Method of Study. The risk to space crew health and safety posed by exposure to space radiation is regarded as a significant obstacle to future human space exploration. To countermand this risk, engineers and designers in today's aerospace community will require detailed knowledge of a broad range of possible materials suitable for the construction of future spacecraft or planetary surface habitats that provide adequate protection from a harmful space radiation environment. This knowledge base can be supplied by developing an experimental method that provides quantitative information about a candidate material's space radiation shielding efficacy with the understanding that (1) shielding is currently the only practical countermeasure to mitigate the effects of space radiation on human interplanetary missions, (2) any mass of a spacecraft or planetary surface habitat necessarily alters the incident flux of ionizing radiation on it, and (3) the delivery of mass into LEO and beyond is expensive and therefore may benefit from the possible use of novel multifunctional materials that could in principle reduce cost as well as ionizing radiation exposure. The developed method has an experimental component using CR-39 PNTD and Al2O3:C OSLD that exposes candidate space radiation shielding materials of varying composition and depth to a representative sample of the GCR spectrum that includes 1 GeV 1H and 1 GeV/n 16O, 28Si, and 56Fe heavy ion beams at the BNL NSRL. The computer modeling component of the method used the Monte Carlo radiation transport code FLUKA to account for secondary neutrons that were not easily measured in the laboratory. Findings and Conclusions. This study developed a method that quantifies the efficacy of a candidate space radiation shielding material relative to the standard of polyethylene using a combination of experimental and computer modeling techniques. The study used established radiation dosimetry techniques to present an empirical weighted figure of merit (WFoM) approach that quantifies the effectiveness of a candidate material to shield space crews from the whole of the space radiation environment. The results of the WFoM approach should prove useful to designers and engineers in seeking alternative materials suitable for the construction of spacecraft or planetary surface habitats needed for long-term space exploration missions. The dosimetric measurements in this study have confirmed the principle of good space radiation shielding design by showing that low-Z¯ materials are most effective at reducing absorbed dose and dose equivalent while high-Z¯ materials are to be avoided. The relatively high WFoMs of carbon composite and lunar- and Martian-regolith composite could have important implications for the design and construction of future spacecraft or planetary surface habitats. The ground-based measurements conducted in this study have validated the heavy ion extension of FLUKA by producing normalized differential LET fluence spectra that are in good agreement with experiment.

DeWitt, Joel Michael

425

Rotating-shield brachytherapy for cervical cancer  

NASA Astrophysics Data System (ADS)

In this treatment planning study, the potential benefits of a rotating shield brachytherapy (RSBT) technique based on a partially-shielded electronic brachytherapy source were assessed for treating cervical cancer. Conventional intracavitary brachytherapy (ICBT), intracavitary plus supplementary interstitial (IS+ICBT), and RSBT treatment plans for azimuthal emission angles of 180° (RSBT-180) and 45° (RSBT-45) were generated for five patients. For each patient, high-risk clinical target volume (HR-CTV) equivalent dose in 2 Gy fractions (EQD2) (?/? = 10 Gy) was escalated until bladder, rectum, or sigmoid colon tolerance EQD2 values were reached. External beam radiotherapy dose (1.8 Gy × 25) was accounted for, and brachytherapy was assumed to have been delivered in 5 fractions. IS+ICBT provided a greater HR-CTV D90 (minimum EQD2 to the hottest 90%) than ICBT. D90 was greater for RSBT-45 than IS+ICBT for all five patients, and greater for RSBT-180 than IS+ICBT for two patients. When the RSBT-45/180 plan with the lowest HR-CTV D90 that was greater than the D90 the ICBT or IS+ICBT plan was selected, the average (range) of D90 increases for RSBT over ICBT and IS+ICBT were 16.2 (6.3-27.2)and 8.5 (0.03-20.16) Gy, respectively. The average (range) treatment time increase per fraction of RSBT was 34.56 (3.68-70.41) min over ICBT and 34.59 (3.57-70.13) min over IS+ICBT. RSBT can increase D90 over ICBT and IS+ICBT without compromising organ-at-risk sparing. The D90 and treatment time improvements from RSBT depend on the patient and shield emission angle.

Yang, Wenjun; Kim, Yusung; Wu, Xiaodong; Song, Qi; Liu, Yunlong; Bhatia, Sudershan K.; Sun, Wenqing; Flynn, Ryan T.

2013-06-01

426

Radiation shielding for underground low-background experiments  

E-print Network

The design task of creating an efficient radiation shield for the new COBRA double-beta decay experiment led to a comprehensive study of commercially available shielding materials. The aim was to find the most efficient combination of materials under the constraints of an extreme low-background experiment operating in a typical underground laboratory. All existing shield configurations for this type of experiment have been found to perform sub-optimally in comparison to the class of multilayered configurations proposed in this study. The method used here to create a specific shield configuration should yield a close to optimal result when applied to any experiment utilising a radiation shield. In particular, the survey of single material response to a given radiation source turns out to give a guideline for the construction of efficient multilayer shields.

D. Y Stewart; P. F. Harrison; B. Morgan; Y. A. Ramachers

2006-07-31

427

Radiation shielding for underground low-background experiments  

E-print Network

The design task of creating an efficient radiation shield for the new COBRA double-beta decay experiment led to a comprehensive study of commercially available shielding materials. The aim was to find the most efficient combination of materials under the constraints of an extreme low-background experiment operating in a typical underground laboratory. All existing shield configurations for this type of experiment have been found to perform sub-optimally in comparison to the class of multilayered configurations proposed in this study. The method used here to create a specific shield configuration should yield a close to optimal result when applied to any experiment utilising a radiation shield. In particular, the survey of single material response to a given radiation source turns out to give a guideline for the construction of efficient multilayer shields.

Stewart, D Y; Morgan, B; Ramachers, Y A

2006-01-01

428

Radiation shielding for underground low-background experiments  

NASA Astrophysics Data System (ADS)

The design task of creating an efficient radiation shield for the new COBRA double-beta decay experiment led to a comprehensive study of commercially available shielding materials. The aim was to find the most efficient combination of materials under the constraints of an extreme low-background experiment operating in a typical underground laboratory. All existing shield configurations for this type of experiment have been found to perform sub-optimally in comparison to the class of multilayered configurations proposed in this study. The method used here to create a specific shield configuration should yield a close to optimal result when applied to any experiment utilising a radiation shield. In particular, the survey of single material response to a given radiation source turns out to give a guideline for the construction of efficient multilayer shields. Note that these proceedings are a short version of a recently submitted, more detailed discussion.

Stewart, D. Y.; Harrison, P. F.; Morgan, B.; Ramachers, Y.

2006-11-01

429

Radiation shielding for underground low-background experiments  

SciTech Connect

The design task of creating an efficient radiation shield for the new COBRA double-beta decay experiment led to a comprehensive study of commercially available shielding materials. The aim was to find the most efficient combination of materials under the constraints of an extreme low-background experiment operating in a typical underground laboratory. All existing shield configurations for this type of experiment have been found to perform sub-optimally in comparison to the class of multilayered configurations proposed in this study. The method used here to create a specific shield configuration should yield a close to optimal result when applied to any experiment utilising a radiation shield. In particular, the survey of single material response to a given radiation source turns out to give a guideline for the construction of efficient multilayer shields. Note that these proceedings are a short version of a recently submitted, more detailed discussion.

Stewart, D. Y.; Harrison, P. F.; Morgan, B.; Ramachers, Y. [University of Warwick, Coventry, CV4 7AL (United Kingdom)

2006-11-17

430

Radiation shielding for underground low-background experiments  

NASA Astrophysics Data System (ADS)

The design task of creating an efficient radiation shield for the new COBRA double-beta decay experiment led to a comprehensive study of commercially available shielding materials. The aim was to find the most efficient combination of materials under the constraints of an extreme low-background experiment operating in a typical underground laboratory. All existing shield configurations for this type of experiment have been found to perform sub-optimally in comparison to the class of multilayered configurations proposed in this study. The method used here to create a specific shield configuration should yield a close to optimal result when applied to any experiment utilising a radiation shield. In particular, the survey of single material response to a given radiation source turns out to give a guideline for the construction of efficient multilayer shields.

Stewart, D. Y.; Harrison, P. F.; Morgan, B.; Ramachers, Y.

2007-02-01

431

Dose distribution under external eye shields for high energy electrons.  

PubMed

Effectiveness of eye shields in reducing the dose to the eye lens from 6 and 9 MeV electron beams from a linear accelerator has been evaluated. The thickness of the shields made from cerrobend was such that only bremsstrahlung photons were transmitted. A shield with a diameter of 1.3 cm and thickness of 1 cm was adequate for the 9 MeV electron beam. The optimum shield to phantom surface distance was 1 cm or less. The same shield with a thickness of 0.5 cm was found to be ineffective with a 6 MeV electron beam. The dose under the shield is greater than predicted by transmission measurements because of the contribution of phantom and electron cone generated scattered electrons. PMID:3080389

Rustgi, S N

1986-01-01

432

Earth Observation  

NASA Technical Reports Server (NTRS)

For pipeline companies, mapping, facilities inventory, pipe inspections, environmental reporting, etc. is a monumental task. An Automated Mapping/Facilities Management/Geographic Information Systems (AM/FM/GIS) is the solution. However, this is costly and time consuming. James W. Sewall Company, an AM/FM/GIS consulting firm proposed an EOCAP project to Stennis Space Center (SSC) to develop a computerized system for storage and retrieval of digital aerial photography. This would provide its customer, Algonquin Gas Transmission Company, with an accurate inventory of rights-of-way locations and pipeline surroundings. The project took four years to complete and an important byproduct was SSC's Digital Aerial Rights-of-Way Monitoring System (DARMS). DARMS saves substantial time and money. EOCAP enabled Sewall to develop new products and expand its customer base. Algonquin now manages regulatory requirements more efficiently and accurately. EOCAP provides government co-funding to encourage private investment in and broader use of NASA remote sensing technology. Because changes on Earth's surface are accelerating, planners and resource managers must assess the consequences of change as quickly and accurately as possible. Pacific Meridian Resources and NASA's Stennis Space Center (SSC) developed a system for monitoring changes in land cover and use, which incorporated the latest change detection technologies. The goal of this EOCAP project was to tailor existing technologies to a system that could be commercialized. Landsat imagery enabled Pacific Meridian to identify areas that had sustained substantial vegetation loss. The project was successful and Pacific Meridian's annual revenues have substantially increased. EOCAP provides government co-funding to encourage private investment in and broader use of NASA remote sensing technology.

1994-01-01

433

Snow shielding factors for cosmogenic nuclide dating inferred from Monte Carlo neutron transport simulations  

NASA Astrophysics Data System (ADS)

Conventional formulations of changes in cosmogenic nuclide production rates with snow cover are based on a mass-shielding approach, which neglects the role of neutron moderation by hydrogen. This approach can produce erroneous correction factors and add to the uncertainty of the calculated cosmogenic exposure ages. We use a Monte Carlo particle transport model to simulate fluxes of secondary cosmic-ray neutrons near the surface of the Earth and vary surface snow depth to show changes in neutron fluxes above rock or soil surface. To correspond with shielding factors for spallation and low-energy neutron capture, neutron fluxes are partitioned into high-energy, epithermal and thermal components. The results suggest that high-energy neutrons are attenuated by snow cover at a significantly higher rate (shorter attenuation length) than indicated by the commonly-used mass-shielding formulation. As thermal and epithermal neutrons derive from the moderation of high-energy neutrons, the presence of a strong moderator such as hydrogen in snow increases the thermal neutron flux both within the snow layer and above it. This means that low-energy production rates are affected by snow cover in a manner inconsistent with the mass-shielding approach and those formulations cannot be used to compute snow correction factors for nuclides produced by thermal neutrons. Additionally, as above-ground low-energy neutron fluxes vary with snow cover as a result of reduced diffusion from the ground, low-energy neutron fluxes are affected by snow even if the snow is at some distance from the site where measurements are made.

Zweck, Christopher; Zreda, Marek; Desilets, Darin

2013-10-01

434

Spatiotemporal relationships of dike magmatism in the Kola region, the Fennoscandian Shield  

NASA Astrophysics Data System (ADS)

A brief geological and petrographic characterization of the Early Precambrian dike complexes of the Kola region is given along with data on new estimates of dike age and analysis of their distribution over the entire Fennoscandian Shield. The emplacement of dikes in the Archean core of the shield continued after consolidation of the sialic crust 2.74-1.76 Ga ago. After the Svecofennian Orogeny, dikes continued to form in the west in the area of newly formed crust, while the amagmatic period began in the Archean domain. The intense formation of dikes in the Svecofennian domain lasted approximately for 1 Ga (1.8-0.84 Ga). The younger igneous rocks in the crustal domains of different age are less abundant and localized at their margins. A similar distribution of dikes is characteristic of other shields in different continents. This implies that the formation of the sialic crust in the shields is not completed by its consolidation and formation of the craton. For 1 Ga after completion of this process, the crust is underplated by mantle-derived magmas. This process is reflected at the Earth's surface in the development of mantle-derived mafic and anorogenic granitoid magmatism. The process of crust formation is ended as the subcratonic lithosphere cools and the amagmatic period of the craton history is started. Beginning from this moment, the manifestations of cratonic magmatism were related either to the superposed tectonomagmatic reactivation of the cold craton under the effect of crust formation in the adjacent mobile belts or to the ascent of mantle plumes.

Fedotov, Zh. A.; Bayanova, T. B.; Serov, P. A.

2012-11-01

435

Ablative heat shield design for space shuttle  

NASA Technical Reports Server (NTRS)

Ablator heat shield configuration optimization studies were conducted for the orbiter. Ablator and reusable surface insulation (RSI) trajectories for design studies were shaped to take advantage of the low conductance of ceramic RSI and high temperature capability of ablators. Comparative weights were established for the RSI system and for direct bond and mechanically attached ablator systems. Ablator system costs were determined for fabrication, installation and refurbishment. Cost penalties were assigned for payload weight penalties, if any. The direct bond ablator is lowest in weight and cost. A mechanically attached ablator using a magnesium subpanel is highly competitive for both weight and cost.

Seiferth, R. W.

1973-01-01

436

Noise Shielding Efficiency in AN Urban System  

NASA Astrophysics Data System (ADS)

To estimate the shielding efficiency of buildings, a model which simulates noise propagation in an urban area has been used. The simulation model assumes the equivalent highway model where vehicles are replaced by equivalent point sources which emit typical traffic noise. Interactions of acoustical waves with obstacles, on the path from the source to the observation point, are reduced to specular reflections from surfaces and diffraction at edges (wedges) of obstacles. The prepared PROP3 computer program allows estimation of sound equivalent level in dB(A) at the observation point in a built-up area, for a highway of known vehicles rate flow and vehicle average speed.

Walerian, E.; Janczur, R.

1998-04-01

437

Equivalent-spherical-shield neutron dose calculations  

SciTech Connect

Neutron doses through 162-cm-thick spherical shields were calculated to be 1090 and 448 mrem/h for regular and magnetite concrete, respectively. These results bracket the measured data, for reinforced regular concrete, of /approximately/600 mrem/h. The calculated fraction of the high-energy (>20 MeV) dose component also bracketed the experimental data. The measured and calculated doses were for a graphite beam stop bombarded with 100 nA of 800-MeV protons. 6 refs., 2 figs., 1 tab.

Russell, G.J.; Robinson, H.

1988-01-01

438

Interstitial rotating shield brachytherapy for prostate cancer  

SciTech Connect

Purpose: To present a novel needle, catheter, and radiation source system for interstitial rotating shield brachytherapy (I-RSBT) of the prostate. I-RSBT is a promising technique for reducing urethra, rectum, and bladder dose relative to conventional interstitial high-dose-rate brachytherapy (HDR-BT). Methods: A wire-mounted 62 GBq{sup 153}Gd source is proposed with an encapsulated diameter of 0.59 mm, active diameter of 0.44 mm, and active length of 10 mm. A concept model I-RSBT needle/catheter pair was constructed using concentric 50 and 75 ?m thick nickel-titanium alloy (nitinol) tubes. The needle is 16-gauge (1.651 mm) in outer diameter and the catheter contains a 535 ?m thick platinum shield. I-RSBT and conventional HDR-BT treatment plans for a prostate cancer patient were generated based on Monte Carlo dose calculations. In order to minimize urethral dose, urethral dose gradient volumes within 0–5 mm of the urethra surface were allowed to receive doses less than the prescribed dose of 100%. Results: The platinum shield reduced the dose rate on the shielded side of the source at 1 cm off-axis to 6.4% of the dose rate on the unshielded side. For the case considered, for the same minimum dose to the hottest 98% of the clinical target volume (D{sub 98%}), I-RSBT reduced urethral D{sub 0.1cc} below that of conventional HDR-BT by 29%, 33%, 38%, and 44% for urethral dose gradient volumes within 0, 1, 3, and 5 mm of the urethra surface, respectively. Percentages are expressed relative to the prescription dose of 100%. For the case considered, for the same urethral dose gradient volumes, rectum D{sub 1cc} was reduced by 7%, 6%, 6%, and 6%, respectively, and bladder D{sub 1cc} was reduced by 4%, 5%, 5%, and 6%, respectively. Treatment time to deliver 20 Gy with I-RSBT was 154 min with ten 62 GBq {sup 153}Gd sources. Conclusions: For the case considered, the proposed{sup 153}Gd-based I-RSBT system has the potential to lower the urethral dose relative to HDR-BT by 29%–44% if the clinician allows a urethral dose gradient volume of 0–5 mm around the urethra to receive a dose below the prescription. A multisource approach is necessary in order to deliver the proposed {sup 153}Gd-based I-RSBT technique in reasonable treatment times.

Adams, Quentin E., E-mail: quentin-adams@uiowa.edu; Xu, Jinghzu; Breitbach, Elizabeth K.; Li, Xing; Rockey, William R.; Kim, Yusung; Wu, Xiaodong; Flynn, Ryan T. [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)] [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Enger, Shirin A. [Medical Physics Unit, McGill University, 1650 Cedar Ave, Montreal, Quebec H3G 1A4 (Canada)] [Medical Physics Unit, McGill University, 1650 Cedar Ave, Montreal, Quebec H3G 1A4 (Canada)

2014-05-15

439

X-ray transmissive debris shield  

DOEpatents

An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

Spielman, R.B.

1996-05-21

440

X-ray transmissive debris shield  

DOEpatents

An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

Spielman, Rick B. (Albuquerque, NM)

1996-01-01

441

CHESS upgrade 1995: Improved radiation shielding (abstract)  

NASA Astrophysics Data System (ADS)

The Cornell Electron Storage Ring (CESR) stores electrons and positrons at 5.3 GeV for the production and study of B mesons, and, in addition, it supplies synchrotron radiation for CHESS. The machine has been upgraded for 300 mA operation. It is planned that each beam will be injected in about 5 minutes and that particle beam lifetimes will be several hours. In a cooperative effort, staff members at CHESS and LNS have studied sources in CESR that produce radiation in the user areas. The group has been responsible for the development and realization of new tunnel shielding walls that provide a level of radiation protection from 20 to ?100 times what was previously available. Our experience has indicated that a major contribution to the environmental radiation is not from photons, but results from neutrons that are generated by particle beam loss in the ring. Neutrons are stopped by inelastic scattering and absorption in thick materials such as heavy concrete. The design for the upgraded walls, the development of a mix for our heavy concrete, and all the concrete casting was done by CHESS and LNS personnel. The concrete incorporates a new material for this application, one that has yielded a significant cost saving in the production of over 200 tons of new wall sections. The material is an artificially enriched iron oxide pellet manufactured in vast quantities from hematite ore for the steel-making industry. Its material and chemical properties (iron and impurity content, strength, size and uniformity) make it an excellent substitute for high grade Brazilian ore, which is commonly used as heavy aggregate in radiation shielding. Its cost is about a third that of the natural ore. The concrete has excellent workability, a 28 day compressive strength exceeding 6000 psi and a density of 220 lbs/cu.ft (3.5 gr/cc). The density is limited by an interesting property of the pellets that is motivated by efficiency in the steel-making application. The pellets are made to be porous, with about 28% of the volume consisting of connected pores of size typically from 1-10 microns. The porosity may have some useful implications for neutron radiation shielding including the possibility of holding a lot more water than a conventional mix, and the opportunity to impregnate the pellets with a good neutron absorber such as boron. This paper will discuss these developments and report the latest results on the effectiveness of the upgraded shielding at Cornell.

Finkelstein, K. D.

1996-09-01

442

Radiation Shielding at High-Energy Electron and Proton Accelerators  

SciTech Connect

The goal of accelerator shielding design is to protect the workers, general public, and the environment against unnecessary prompt radiation from accelerator operations. Additionally, shielding at accelerators may also be used to reduce the unwanted background in experimental detectors, to protect equipment against radiation damage, and to protect workers from potential exposure to the induced radioactivity in the machine components. The shielding design for prompt radiation hazards is the main subject of this chapter.

Rokni, Sayed H.; /SLAC; Cossairt, J.Donald; /Fermilab; Liu, James C.; /SLAC

2007-12-10

443

Evergreen trees as inexpensive radiation shields for temperature sensors  

Microsoft Academic Search

Evergreen trees provide temperature sensors with shielding from solar radiation and an elevated location above the snowpack. Sensors were deployed with simple funnel radiation shields in the Sierra Nevada, California, and Rocky Mountains, Colorado. Compared with unaspirated, Gill-shielded thermistors, inexpensive self-recording temperature sensors hung in dense stands of trees have less than 0.8°C (0.4°C) mean difference in daily maximum (mean)

Jessica D. Lundquist; Brian Huggett

2008-01-01

444

Methods and Procedures for Shielding Analyses for the SNS  

SciTech Connect

In order to provide radiologically safe Spallation Neutron Source operation, shielding analyses are performed according to Oak Ridge National Laboratory internal regulations and to comply with the Code of Federal Regulations. An overview of on-going shielding work for the accelerator facility and neutrons beam lines, methods, used for the analyses, and associated procedures and regulations is presented. Methods used to perform shielding analyses are described as well.

Gallmeier, Franz X [ORNL] [ORNL; Iverson, Erik B [ORNL] [ORNL; Remec, Igor [ORNL] [ORNL; Lu, Wei [ORNL] [ORNL; Popova, Irina [ORNL] [ORNL

2014-01-01

445

Radiation shield analysis for a manned Mars rover  

Microsoft Academic Search

Radiation shielding for unmanned space missions has been extensively studied; however, designs of man-rated shields are minimal. Engle et al.'s analysis of a man-rated, multilayered shield composed of two and three cycles (a cycle consists of a tungsten and a lithium hydride layer) is the basis for the work reported in this paper. The authors present the results of a

N. J. Morley; M. S. ElGenk

1991-01-01

446

Polyethylene/Boron Composites for Radiation Shielding Applications  

NASA Astrophysics Data System (ADS)

Multifunctional composites made with boron are absorbers of low energy nuetrons, and could be used for structural shielding materials. Polyethylene/boron carbide composites were fabricated using conventional polymer processing techniques, and were evaluated for mechanical and radiation shielding properties. Addition of neat boron carbide (powder and nanoparticles) to an injection molding grade HPDE showed superior mechanical properties compared to neat HDPE. Radiation shielding measurements of a 2 wt% boron carbide composite were improved over those of the neat polyethylene.

Harrison, Courtney; Burgett, Eric; Hertel, Nolan; Grulke, Eric

2008-01-01

447

Experimental tests of neutron shielding for the ATLAS forward region  

Microsoft Academic Search

Experimental tests devoted to the optimization of the neutron shielding for the ATLAS forward region were performed at the CERN-PS with a 4GeV\\/c proton beam. Spectra of fast neutrons, slow neutrons and gamma rays escaping a block of iron (40×40×80cm3) shielded with different types of neutron and gamma shields (pure polyethylene – PE; borated polyethylene – BPE; lithium filled polyethylene

S. Posp??šil; I. Štekl; T. ?echák; P. ?ermák; J. Kluso?; J. Kon???ek; J. Konícek; V. Linhart; M. Ši?or; C. Leroy; Z. Doležal; R. Leitner; G. Lukhanin; K. Soustružn??k; M. Lokaj???ek; S. N?me?ek; J. Palla; J. Sodomka

1999-01-01

448

Fast neutron shielding and neutron transport studies at YAYOI  

Microsoft Academic Search

The fast neutron shielding experiments at the fast neutron source reactor YAYOI of the University of Tokyo were summarized. The experiments were grouped into the following four types; 1.(1)|experiments for shield design of fast breeder reactor,2.(2)|fast neutron transmission experiments,3.(3)|fast neutron streaming experiments,4.(4)|neutron skyshine experiment. The experimental data are useful for shield design and assessing the accuracy of the calculational methods.The

Y. Oka; K. Furuta; S. An

1998-01-01

449

Experimental Tests of Neutron Shielding for the ATLAS Forward Region  

Microsoft Academic Search

Experimental tests devoted to the optimization of the neutron shielding for the ATLAS forward region were performed at the CERN-PS with a 4 GeV\\/c proton beam. Spectra of fast neutrons, slow neutrons and gamma rays escaping a block of iron (40$\\\\times$40$\\\\times$80 cm$^3$) shielded with different types of neutron and gamma shields (pure polyethylene - PE, borated polyethylene - BPE, lithium

S Pospísil; I Stekl; T Cechák; P Cermák; J Jakubek; J Kluson; J Konícek; J Kubasta; V Linhart; M Sinor; C Leroy; Z Dolezal; R Leitner; G A Lukianov; K Soustruznik; M Lokajícek; S Némécek; G Pálla; J Sodomka

1998-01-01

450

Polyethylene/Boron Composites for Radiation Shielding Applications  

SciTech Connect

Multifunctional composites made with boron are absorbers of low energy nuetrons, and could be used for structural shielding materials. Polyethylene/boron carbide composites were fabricated using conventional polymer processing techniques, and were evaluated for mechanical and radiation shielding properties. Addition of neat boron carbide (powder and nanoparticles) to an injection molding grade HPDE showed superior mechanical properties compared to neat HDPE. Radiation shielding measurements of a 2 wt% boron carbide composite were improved over those of the neat polyethylene.

Harrison, Courtney; Grulke, Eric [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States); Burgett, Eric; Hertel, Nolan [Neely Nuclear Research Center, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

2008-01-21

451

Calculation of the shielding effect of solid shell enclosures  

NASA Astrophysics Data System (ADS)

A program which determines the shielding effect of solid-shell enclosures against EMP, which presents results as tables and graphs, is presented. Knowledge of shield permeability and conductivity, the basic model to be used, and the dimensions of the model are required. A standard field pulse is incorporated in the program, but the pulse parameters may be changed by the user. The program plots graphs of the external field pulse, the field pulse within the enclosure and the shielding efficiency.

Garthwaite, F. G. L.

1983-04-01

452

Development of special radiation shielding concretes using natural local materials and evaluation of their shielding characteristics  

Microsoft Academic Search

Two types of typical concretes widely used in Syria (in Damascus and Aleppo) and four other types of concretes, using aggregates from different regions, have been prepared. The shielding properties of these six types were studied for gamma ray (from Cs-137 and Co-60 sources) and for neutrons (from Am–Be source). A reduction of about 10% in the HVL was obtained

M. H. Kharita; M. Takeyeddin; M. Alnassar; S. Yousef

2008-01-01

453

Cosmic ray environment model for Earth orbit  

NASA Technical Reports Server (NTRS)

A set of computer codes, which include the effects of the Earth's magnetic field, used to predict the cosmic ray environment (atomic numbers 1 through 28) for a spacecraft in a near-Earth orbit is described. A simple transport analysis is used to approximate the environment at the center of a spherical shield of arbitrary thickness. The final output is in a form (a Heinrich Curve) which has immediate applications for single event upset rate predictions. The codes will culate the time average environment for an arbitrary number (fractional or whole) of circular orbits. The computer codes were run for some selected orbits and the results, which can be useful for quick estimates of single event upset rates, are given. The codes were listed in the language HPL, which is appropriate or a Hewlett Packard 9825B desk top computer. Extensive documentation of the codes is available from COSMIC, except where explanations have been deferred to references where extensive documentation can be found. Some qualitative aspects of the effects of mass and magnetic shielding are also discussed.

Edmonds, L.

1985-01-01

454

71. Joe Moore, Photographer. September, 1996. BEVATRON ROOF SHIELDING AND ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

71. Joe Moore, Photographer. September, 1996. BEVATRON ROOF SHIELDING AND BUILDING TRUSS STRUCTURE - University of California Radiation Laboratory, Bevatron, 1 Cyclotron Road, Berkeley, Alameda County, CA

455

Modelling of electromagnetic shielding structures for radiated EMI analysis.  

E-print Network

??Electromagnetic (EM) shielding has been used extensively in electronic products to reduce the radiated electromagnetic interference (EMI) from high-speed digital circuits so that the products… (more)

Wang, Zheng.

2008-01-01

456

Beam extraction from a synchrotron through a magnetic shield  

NASA Astrophysics Data System (ADS)

A new beam extraction scheme from a synchrotron is put forward. The main difference from other schemes of extraction is the use of magnetic shields instead of a septum. Magnetic shields are located in the central dipole magnets of a pulsed chicane. The magnetic shield is a multilayer copper-iron tube. Numerical simulations and experimental results for the magnetic shield are presented. A good accordance between them has been shown. The advantages and the area of application of the new extraction scheme are discussed. The proposed scheme will be used for extraction from a booster synchrotron to a storage ring in a new synchrotron radiation source in Novosibirsk.

Bondarenko, A. V.; Vinokurov, N. A.

2009-05-01

457

Shield Design for a Space Based Vapor Core Reactor  

SciTech Connect

Innovative shielding strategies were sought to reduce the mass of the required shielding for a space based vapor core reactor system with magnetohydrodynamic energy conversion. Gamma-rays directly resultant from fission were found to play no role in the dose rate, while secondary gamma-rays from fission neutron interactions were the dominant contributor to the dose rate. Hydrogen containing materials such as polyethylene were utilized to provide shielding of both radiation from the reactor complex and also solar and galactic cosmic radiation. This shield design was found to contribute 0.125 kg/kWe to the baseline vapor core reactor system specific mass. (authors)

Knight, Travis; Anghaie, Samim [Innovative Nuclear Space Power and Propulsion Institute (INSPI), PO Box 116502, University of Florida, Gainesville, FL 32611-6502 (United States)

2002-07-01

458

Graphene shield enhanced photocathodes and methods for making the same  

DOEpatents

Disclosed are graphene shield enhanced photocathodes, such as high QE photocathodes. In certain embodiments, a monolayer graphene shield membrane ruggedizes a high quantum efficiency photoemission electron source by protecting a photosensitive film of the photocathode, extending operational lifetime and simplifying its integration in practical electron sources. In certain embodiments of the disclosed graphene shield enhanced photocathodes, the graphene serves as a transparent shield that does not inhibit photon or electron transmission but isolates the photosensitive film of the photocathode from reactive gas species, preventing contamination and yielding longer lifetime.

Moody, Nathan Andrew

2014-09-02

459

Earth's Mineral Evolution  

E-print Network

Earth's Mineral Evolution :: Astrobiology Magazine - earth science - evol...rth science evolution Extreme Life Mars Life Outer Planets Earth's Mineral Evolution Summary (Nov 14, 2008): New research. Display Options: Earth's Mineral Evolution Based on a CIW news release Mineral Kingdom Has Co

Downs, Robert T.

460

Crew Earth Observations  

NASA Technical Reports Server (NTRS)

Crew Earth Observations (CEO) takes advantage of the crew in space to observe and photograph natural and human-made changes on Earth. The photographs record the Earth's surface changes over time, along with dynamic events such as storms, floods, fires and volcanic eruptions. These images provide researchers on Earth with key data to better understand the planet.

Runco, Susan

2009-01-01

461

Earth Structure Introduction  

E-print Network

Earth Structure Introduction Earth Structure (2nd Edition), 2004 W.W. Norton & Co, New York Slide show by Ben van der Pluijm © WW Norton, unless noted otherwise #12;© EarthStructure (2nd ed) 210/4/2010 Aerial views #12;© EarthStructure (2nd ed) 310/4/2010 http://www.globalchange.umich.edu/Ben/ES/ #12

462

Why Earth Science?  

ERIC Educational Resources Information Center

This article briefly describes Earth science. The study of Earth science provides the foundation for an understanding of the Earth, its processes, its resources, and its environment. Earth science is the study of the planet in its entirety, how its lithosphere, atmosphere, hydrosphere, and biosphere work together as systems and how they affect…

Smith, Michael J.

2004-01-01

463

SHIELDING ANALYSIS FOR PORTABLE GAUGING COMBINATION SOURCES  

SciTech Connect

Radioisotopic decay has been used as a source of photons and neutrons for industrial gauging operations since the late 1950s. Early portable moisture/density gauging equipment used Americium (Am)-241/Beryllium (Be)/Cesium (Cs)-137 combination sources to supply the required nuclear energy for gauging. Combination sources typically contained 0.040 Ci of Am-241 and 0.010 Ci of CS-137 in the same source capsule. Most of these sources were manufactured approximately 30 years ago. Collection, transportation, and storage of these sources once removed from their original device represent a shielding problem with distinct gamma and neutron components. The Off-Site Source Recovery (OSR) Project is planning to use a multi-function drum (MFD) for the collection, shipping, and storage of AmBe sources, as well as the eventual waste package for disposal. The MFD is an approved TRU waste container design for DOE TRU waste known as the 12 inch Pipe Component Overpack. As the name indicates, this drum is based on a 12 inch ID stainless steel weldment approximately 25 inch in internal length. The existing drum design allows for addition of shielding within the pipe component up to the 110 kg maximum pay load weight. The 12 inch pipe component is packaged inside a 55-gallon drum, with the balance of the interior space filled with fiberboard dunnage. This packaging geometry is similar to the design of a DOT 6M, Type B shipping container.

J. TOMPKINS; L. LEONARD; ET AL

2000-08-01

464

MicroShield/ISOCS gamma modeling comparison.  

SciTech Connect

Quantitative radiological analysis attempts to determine the quantity of activity or concentration of specific radionuclide(s) in a sample. Based upon the certified standards that are used to calibrate gamma spectral detectors, geometric similarities between sample shape and the calibration standards determine if the analysis results developed are qualitative or quantitative. A sample analyzed that does not mimic a calibrated sample geometry must be reported as a non-standard geometry and thus the results are considered qualitative and not quantitative. MicroShieldR or ISOCSR calibration software can be used to model non-standard geometric sample shapes in an effort to obtain a quantitative analytical result. MicroShieldR and Canberra's ISOCSR software contain several geometry templates that can provide accurate quantitative modeling for a variety of sample configurations. Included in the software are computational algorithms that are used to develop and calculate energy efficiency values for the modeled sample geometry which can then be used with conventional analysis methodology to calculate the result. The response of the analytical method and the sensitivity of the mechanical and electronic equipment to the radionuclide of interest must be calibrated, or standardized, using a calibrated radiological source that contains a known and certified amount of activity.

Sansone, Kenneth R

2013-08-01

465

Liquid Vortex Shielding for Fusion Energy Applications  

SciTech Connect

Swirling liquid vortices can be used in fusion chambers to protect their first walls and critical elements from the harmful conditions resulting from fusion reactions. The beam tube structures in heavy ion fusion (HIF) must be shielded from high energy particles, such as neutrons, x-rays and vaporized coolant, that will cause damage. Here an annular wall jet, or vortex tube, is proposed for shielding and is generated by injecting liquid tangent to the inner surface of the tube both azimuthally and axially. Its effectiveness is closely related to the vortex tube flow properties. 3-D particle image velocimetry (PIV) is being conducted to precisely characterize its turbulent structure. The concept of annular vortex flow can be extended to a larger scale to serve as a liquid blanket for other inertial fusion and even magnetic fusion systems. For this purpose a periodic arrangement of injection and suction holes around the chamber circumference are used, generating the layer. Because it is important to match the index of refraction of the fluid with the tube material for optical measurement like PIV, a low viscosity mineral oil was identified and used that can also be employed to do scaled experiments of molten salts at high temperature.

Bardet, Philippe M. [University of California, Berkeley (United States); Supiot, Boris F. [University of California, Berkeley (United States); Peterson, Per F. [University of California, Berkeley (United States); Savas, Oemer [University of California, Berkeley (United States)

2005-05-15

466

Twin jet shielding. [for aircraft noise reduction  

NASA Technical Reports Server (NTRS)

For an over-the-wing/under-the-wing engine configuration on an airplane, the noise produced by the upper jet flow is partially reflected by the lower jet. An analysis has been performed which can be used to predict the distribution of perceived noise levels along the ground plane at take-off for an airplane which is designed to take advantage of the over/under shielding concept. Typical contours of PNL, the shielding benefit in the shadow zone, and the EPNL values at 3.5 nautical miles from brake release as well as EPNL values at sideline at 0.35 nautical miles have been calculated. This has been done for a range of flow parameters characteristic of engines producing inverted velocity profile jets suitable for use in a supersonic cruise vehicle. Reductions up to 6.0 EPNdB in community noise levels can be realized when the over engines are operated at higher thrust and the lower engines simultaneously operated with reduced thrust keeping the total thrust constant.

Parthasarathy, S. P.; Cuffel, R. F.; Massier, P. F.

1979-01-01

467

The sternum as an electrical shield.  

PubMed

Introduction - The TASER(®) conducted electrical weapon (CEW) delivers electrical pulses that can temporarily incapacitate subjects. We analyzed the distribution of TASER CEW currents in tissues posterior to the sternum to understand the likelihood of triggering cardiac arrhythmias. We also assessed the electrical `shielding' effects of the sternum. Methods and Results - Finite element modeling (FEM) was used to approximate the current density and electric field strength in tissues around the sternum. We analyzed 2 CEW dart deployment scenarios: (a) both darts over the anterior aspect of the sternum; and (b) a CEW dart anterior to the sternum and the other over the abdomen. In both scenarios, the sternum provided significant attenuation of CEW currents. Particularly, both FEMs predicted that the residual electrical current or charge from CEWs would be insufficient to cause either cardiac capture or induction of ventricular fibrillation at locations where cardiac tissue would reside relative to the posterior aspect of the sternum. Conclusion - The sternum offers significant `shielding' effect and protects the tissues posterior to it against effects of electrical current flow from anteriorly-placed CEW electrodes. PMID:25570983

Panescu, Dorin; Kroll, Mark; Iverson, Carlyn; Brave, Michael

2014-08-01

468

Gas Shielding Technology for Welding and Brazing  

NASA Technical Reports Server (NTRS)

Welding is a common method that allows two metallic materials to be joined together with high structural integrity. When joints need to be leak-tight, light-weight, or free of contaminant-trapping seams or surface asperities, welding tends to be specified. There are many welding techniques, each with its own advantages and disadvantages. Some of these techniques include Forge Welding, Gas Tungsten Arc Welding, Friction Stir Welding, and Laser Beam Welding to name a few. Whichever technique is used, the objective is a structural joint that meets the requirements of a particular component or assembly. A key practice in producing quality welds is the use of shielding gas. This article discusses various weld techniques, quality of the welds, and importance of shielding gas in each of those techniques. Metallic bonds, or joints, are produced when metals are put into intimate contact. In the solid-state "blacksmith welding" process, now called Forge Welding (FOW), the site to be joined is pounded into intimate contact. The surfaces to be joined usually need to be heated to make it easier to deform the metal. The surfaces are sprinkled with a flux to melt surface oxides and given a concave shape so that surface contamination can be squeezed out of the joint as the surfaces are pounded together; otherwise the surface contamination would be trapped in the joint and would weaken the weld. In solid-state welding processes surface oxides or other contamination are typically squeezed out of the joint in "flash."

Nunes, Arthur J.; Gradl, Paul R.

2012-01-01

469

Structure and metamorphism of the Antarctic Shield  

NASA Astrophysics Data System (ADS)

The information on the composition, structure, P-T conditions of metamorphic facies, evolution, and time of the metamorphic events in the largest Precambrian tectonic provinces of the Antarctic Crystalline Shield gained over more than a half-century is summarized in this paper. The joining up of the ortho- and paracrystalline rocks into complexes and groups according to their geographic position, composition, age, and the character of their metamorphism allowed us to consider the main features of the structure and evolution of the provinces including (1) the near-latitudinal polycyclic Late Precambrian-Early Paleozoic Wegener-Mawson Mobile Belt, extended for more than 4000 km, which started to evolve in the Mesoproterozoic and stabilized only at the end of Cambrian; (2) the Early Precambrian relict crystalline protocratonic blocks adjoining this mobile belt; their history is traced from the Eoarchean; and (3) the near-latitudinal Late Precambrian-Early Paleozoic aulacogen in the southern protocratonic block. The P-T conditions of the metamorphism from the pyroxene-granulite subfacies in the protocratonic blocks to the greenschist facies in aulacogen, as well as the age of the magmatic and metamorphic events in all the tectonic provinces of the shield, are characterized. This made it possible to consider the metamorphic history and conditions of the continental crust's formation in Antarctica, where the oldest crystalline rocks are dated to the Eoarchean (4060-3850 Ma) and the youngest rocks are ˜500 Ma old.

Kamenev, E. N.; Maslov, V. A.; Semenov, V. S.; Kurinin, R. G.; Mikhailov, V. M.; Alekseev, N. L.; Kamenev, I. A.; Semenov, S. V.

2013-03-01

470

Deoxyribonucleic acid-Ag nanoparticles for EMI Shielding: the effect of nanoparticle size, shape and distribution on the shielding effectiveness  

NASA Astrophysics Data System (ADS)

This study focuses on the use of silver based nanoparticle as fillers in DNA host materials to form nancomposites for applications in Electro-Magnetic Interferences (EMI) shielding. For relatively low-conductivity EMI shielding nanocomposites, silver-oxide coated cenospheres are investigated as fillers. The filler loadings are varied to determine a percolation threshold for the desired low conductivity and shielding effectiveness. Microwave absorption as well as DC surface resistivity measurements are undertaken to characterize the obtained films.

Ouchen, Fahima; Wilson, Benjamin G.; Yaney, Perry P.; Salour, Michael M.; Grote, James G.

2014-09-01

471

Exploring Earth from Space  

NSDL National Science Digital Library

This set of lithographs from the ISS EarthKAM program contains an educators' guide, student information and worksheets, and several Earth photos taken from the Space Shuttle. Shuttle astronauts and the ISS EarthKAM program provide photos of our planet from the unique perspective of Earth orbit. This resource can enhance students' studies of Earth and space science, geography, social studies, mathematics, and educational technologies.

2002-12-01

472

Earth Observatory Glossary  

NSDL National Science Digital Library

The Earth Observatory Glossary defines words from space science, ecology and Earth science. It is part of the NASA Earth Observatory site, which provides new satellite imagery and scientific information about Earth with a focus on climate and environmental change. The new glossary mode allows users to browse the Earth Observatory site with special terms highlighted that, when selected, will take you to the appropriate entry in the glossary.

473

S3G\\/S4G PRIMARY SHIELD WATER SYSTEM DESIGN DESCRIPTION  

Microsoft Academic Search

The function of the Shield Water System is to provide shielding to ; protect personnel from excessive neutron radiation. Shielding is accomplished by ; enclosing the pressure vessel sides and bottom in an annular shaped tank which is ; maintained full of water at atmospheric pressure. The Shield Water System ; consists of the neutron shield tank which surrounds the

Krauss

1957-01-01

474

Application of a dummy eye shield for electron treatment planning  

PubMed Central

Metallic eye shields have been widely used for near-eye treatments to protect critical regions, but have never been incorporated into treatment plans because of the unwanted appearance of the metal artifacts on CT images. The purpose of this work was to test the use of an acrylic dummy eye shield as a substitute for a metallic eye shield during CT scans. An acrylic dummy shield of the same size as the tungsten eye shield was machined and CT scanned. The BEAMnrc and the DOSXYZnrc were used for the Monte Carlo (MC) simulation, with the appropriate material information and density for the aluminum cover, steel knob and tungsten body of the eye shield. The Pinnacle adopting the Hogstrom electron pencil-beam algorithm was used for the one-port 6-MeV beam plan after delineation and density override of the metallic parts. The results were confirmed with the metal oxide semiconductor field effect transistor (MOSFET) detectors and the Gafchromic EBT2 film measurements. For both the maximum eyelid dose over the shield and the maximum dose under the shield, the MC results agreed with the EBT2 measurements within 1.7%. For the Pinnacle plan, the maximum dose under the shield agreed with the MC within 0.3%; however, the eyelid dose differed by –19.3%. The adoption of the acrylic dummy eye shield was successful for the treatment plan. However, the Pinnacle pencil-beam algorithm was not sufficient to predict the eyelid dose on the tungsten shield, and more accurate algorithms like MC should be considered for a treatment plan. PMID:22915776

Kang, Sei-Kwon; Park, Soah; Hwang, Taejin; Cheong, Kwang-Ho; Han, Taejin; Kim, Haeyoung; Lee, Me-Yeon; Kim, Kyoung Ju; Oh, Do Hoon; Bae, Hoonsik

2013-01-01

475

Hydrogeologic Controls on the Deep Terrestrial Biosphere - Chemolithotrophic Energy for Subsurface Life on Earth and Mars  

Microsoft Academic Search

As exploration for gold, diamonds and base metals expand mine workings to depths of almost 3 km below the Earth's surface, the mines of the Canadian Shield provide a window into the deep biosphere as diverse, but to date less well-explored than the South African Gold Mines. To date investigations of the deep biosphere have, in most cases, focused on

B. Sherwood Lollar; J. Moran; S. Tille; K. Voglesonger; G. Lacrampe-Couloume; T. Onstott; L. Pratt; G. Slater

2009-01-01

476

Concerning the system earth during geomagnetic polarity transitions: Impact on the neutral atmosphere  

Microsoft Academic Search

During a geomagnetic polarity transition, the strength and structure of the earth geomagnetic field can vary very much from the current state. This means that regions which are at the moment shielded from extraterrestrical energetic particles can become subject to particle precipition. We use a 2 dimensional chemistry, photolysis and transport model of the atmosphere to investigate how different configurations

M. von Koenig; J. Burrows; K. Kuenzi; E. Wolff; M. Kallenrode

2003-01-01