Showing papers on "Shields published in 2015"
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TL;DR: Earth pressure balance (EPB-) Shields were originally used in fine-grained soils as well as in mixed-grain soils with a content of fine (d) as mentioned in this paper.
91 citations
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TL;DR: In this article, the performance of Whipple shields integrated with layers of metallic glasses was compared with a baseline target analogue of one of the shields similar to what is used on the International Space Station.
Abstract: In this work, hypervelocity impact tests up to 7 km · s−1 are used to compare the performance of Whipple shields integrated with layers of metallic glasses with a baseline target analogue of one of the shields similar to what is used on the International Space Station. The baseline target failed under the impact while the target utilizing metallic glass as a replacement for the fabric layers in the baseline passed the test. The paper postulates on the prospects of future implementation of metallic glasses as spacecraft debris shields.
31 citations
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18 Jun 2015TL;DR: In this paper, a stationary induction apparatus includes an electric functional unit, a core, a tank containing the electric functional units, high-voltage leads leading out from the windings, and low-voltages leading out of the leads.
Abstract: Leakage fluxes from windings and leads of a stationary induction apparatus are confined within a tank. The stationary induction apparatus includes an electric functional units each including a winding and a core, a tank containing the electric functional units, high-voltage leads leading out from the windings, and low-voltage leads leading out from the windings. Magnetic shields are placed on the inner surface of a wall of the tank through which the high-voltage leads are drawn out of the tank, and a composite shield formed by combining nonmagnetic shields and magnetic shields is placed on the inner surface of a wall of the tank facing the low-voltage leads and is electrically short-circuited.
30 citations
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TL;DR: In this article, the authors used pipe-shaped radiation shields called duct shields for KAGRA in Japan, one of the cryogenic interferometric gravitational wave detectors, and measured the thermal radiation coming through the duct shields.
Abstract: One of the most important challenges in cryogenic interferometric gravitational wave detectors is to reduce the undesirable thermal radiation coming through holes in the radiation shield, which are necessary for the laser beam to pass through. For this purpose, pipe-shaped radiation shields called duct shields are used. Here, we have manufactured duct shields for KAGRA in Japan, one of the cryogenic interferometric gravitational wave detectors, and measured the thermal radiation coming through the duct shields. The measured result was found to be consistent with the calculation result that the duct shield can reduce the thermal radiation to less than 1%. This fact confirmed that the amount of thermal radiation coming through the duct shields was smaller than KAGRA?s requirement.
19 citations
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TL;DR: In this article, magnetic shielding properties of 40 mm wide second generation high temperature superconducting (2GHTS) materials were studied at variable temperatures, and the effect of lower temperatures is particularly visible at higher magnetic fields.
Abstract: Magnetic shielding characteristics of 40 mm wide second generation high temperature superconducting (2GHTS) materials were studied at variable temperatures. Shielding characteristics were measured in DC and variable frequency AC magnetic fields at a range of magnitudes up to 60 mT. Magnetic shields fabricated in the form of short cylinders were studied with magnetic field perpendicular to their axis. Shielding properties of single and double layer shields were compared at various temperatures between 50 and 80 K. Shielding factor up to 98% was achieved. The benefit of lower temperatures is particularly visible at higher magnetic fields. Trends of shielding characteristics modeled as a function of external magnetic field strength with finite element models using COMSOL match with those of the experimental observations.
17 citations
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TL;DR: In this article, the authors present the results of measurements of the shielding efficiency of multilayer-film electromagnetic shields, which represent alternating layers of materials with high magnetic permeability (Ni-Fe) and high conductivity (Cu).
Abstract: Electrodeposited multilayer-film electromagnetic shields are very promising for protecting various devices due to high shielding efficiency and the possibility of depositing on complex-shaped objects. In this communication, we present the results of measurements of the shielding efficiency of such shields. The shields represent alternating layers of materials with high magnetic permeability (Ni-Fe) and high conductivity (Cu). The maximum number of double layers is 45. It is shown that the shielding efficiency in the weak magnetic fields (0.1–0.2 mT) is 8–10; at higher magnetic field strengths (1.5–2.5 mT), it reaches 80–100. It is shown that the shielding factor increases with the number of layers in the shield at the same thickness of a soft magnetic material. A permalloy shield at the same amount of a soft magnetic material has an efficiency lower by a factor of 3–15 depending on the magnetic field strength.
16 citations
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01 Oct 2015TL;DR: In this paper, an experimental investigation on the thermal behavior of medium voltage underground cables laid in different types of soils and under different conditions of the ambient temperatures was carried out and the results of visual inspections of failed cable joints, due to thermal causes.
Abstract: The present paper reports an experimental investigation on the thermal behavior of medium voltage underground cables laid in different types of soils and under different conditions of the ambient temperatures. The same paper shows as thermal degradation of the insulating system of the cables and their joints can become more consistent and faster due to the effect of the continuously overheating due to the ambient temperatures and to the thermal resistivity of the soil of higher values. An other source of thermal degradation of the cables and their joints may be indicated in the fault currents affecting the metallic shields in systems operating with a compensated neutral connection to ground. In particular, in these systems the fault current is lasted for a time of some tens of seconds to allow a faster localization of the failure, through the automatic sectioning switches. During this time, currents flow through the metallic shields of the cables, overheating the same shields especially in correspondence of pour connections which may be present inside the joints. In case that the single-fault-to-ground evolves in a double-fault-to-ground the same shield will be interested by much higher current (short-circuit) which will create a deeper degradation of the semiconductive compounds and the insulation located nearby the metallic shields. The paper also presents the results of visual inspections of failed cable joints, due to thermal causes. Based on these considerations, important solutions may be indicated to reduce the failure rate of the MV electrical system allowing improvements in the overall power quality of the entire electrical systems.
15 citations
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TL;DR: In this paper, a new method using jet-charges for testing shields developed for spacecraft protection against micrometeoroids and man-made debris is introduced, and a test pattern for obtaining a gradient-free, explosively formed jet is considered.
15 citations
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TL;DR: The three-layered shield, composed of tungsten, bismuth and gadolinium, showed the most significant attenuation properties in radiology, with acceptable shielding at 140 keV energy in nuclear medicine.
Abstract: Introduction Lead-based shields are the most widely used attenuators in X-ray and gamma ray fields. The heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. Materials and Methods The purpose of this study was to design multi-layered shields for protection against X-rays and gamma rays in diagnostic radiology and nuclear medicine. In this study, cubic slabs composed of several materials with high atomic numbers, i.e., lead, barium, bismuth, gadolinium, tin and tungsten, were simulated, using MCNP5 Monte Carlo code. Cubic slabs (30×30×0.05 cm3) were simulated at a 50 cm distance from the point photon source. The X-ray spectra of 80 kVp and 120 kVp were obtained, using IPEM Report 78. The photon flux following the use of each shield was obtained inside cubic tally cells (1×1×0.5 cm3) at a 5 cm distance from the shields. The photon attenuation properties of multi-layered shields (i.e., two, three, four and five layers), composed of non-lead radiation materials, were also obtained via Monte Carlo simulations. Results Among different shield designs proposed in this study, the three-layered shield, composed of tungsten, bismuth and gadolinium, showed the most significant attenuation properties in radiology, with acceptable shielding at 140 keV energy in nuclear medicine. Conclusion According to the results, materials with k-edges equal to energies common to diagnostic radiology can be proper substitutes for lead shields.
8 citations
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21 Jan 2015
TL;DR: In this article, the authors proposed a star sensor temperature control device which comprises star sensors, light shields, flange plates, installation supports, multi-layer heat insulation assemblies and heaters.
Abstract: The invention provides a star sensor temperature control device which comprises star sensors, light shields, flange plates, installation supports, multi-layer heat insulation assemblies and heaters. The head of each star sensor and the corresponding light shield are installed on one side of the corresponding flange plate and connected with the corresponding installation support through the flange plate. The heaters are arranged at the heads of the star sensors. The light shields are connected to the other sides of the flange plates. The outer surfaces of the light shields and the outer surfaces of the installation supports are covered with the multi-layer heat insulation assemblies. The star sensor temperature control device further comprises heat control coatings arranged on the non-installation faces of the flange plates and the outer surfaces of the heads of the star sensors. According to the star sensor temperature control device, the heat dissipation capacity is improved through forming heat dissipation openings and increasing the heat dissipation area, measures such as arrangement of the light shields and the like are taken, and therefore the requirement for heat dissipation of current star sensors can be met; meanwhile, the low-temperature keeping requirement of the star sensors can be met through the main and standby compensation electric heaters, so that the temperature control effect is good.
8 citations
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TL;DR: In this paper, an analytical method is proposed to estimate the performance of passive thermal shields in the frequency domain, which allows for fast evaluation and optimization and reveals interesting properties of the shields, such as dips in the transfer function for some frequencies under certain combinations of materials and geometries.
Abstract: Modern experiments aiming at tests of fundamental physics, like measuring gravitational waves or testing Lorentz Invariance with unprecedented accuracy, require thermal environments that are highly stable over long times. To achieve such a stability, the experiment including typically an optical resonator is nested in a thermal enclosure, which passively attenuates external temperature fluctuations to acceptable levels. These thermal shields are usually designed using tedious numerical simulations or with simple analytical models. In this paper, we propose an accurate analytical method to estimate the performance of passive thermal shields in the frequency domain, which allows for fast evaluation and optimization. The model analysis has also unveiled interesting properties of the shields, such as dips in the transfer function for some frequencies under certain combinations of materials and geometries. We validate the results by comparing them to numerical simulations performed with commercial software based on finite element methods.
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TL;DR: A superconducting undulator (SCU) prototype with a period of 16 mm and a magnetic gap of 8 mm has been under design and fabrication at the Shanghai Institute of Applied Physics in China since late 2013 as mentioned in this paper.
Abstract: A superconducting undulator (SCU) prototype with a period of 16 mm and a magnetic gap of 8 mm has been under design and fabrication at the Shanghai Institute of Applied Physics in China since late 2013 The SCU prototype is aimed at obtaining the magnetic field of 088 T at the beam axis A set of support systems was designed to support the cold masses, including superconducting coils, a beam chamber, and thermal shields A set of self-centering cold mass supports are adopted for the superconducting magnet for the purpose of self-alignment at low temperature The beam chamber is supported by G-10 spacers against the magnet The nonmetallic tension rods and spacers are used to support the 60- and 20-K thermal shields, respectively The heat loads conducted to the cold masses through the supports need to be minimized This paper presents the design details of the support system
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TL;DR: The neutral beam copper pole shields currently in service at DIII-D have experienced localized melting and fatigue cracks in the grooves machined in the back of the copper plates.
Abstract: The neutral beam copper pole shields currently in service at DIII-D have experienced localized melting and fatigue cracks in the grooves machined in the back of the copper plates. Higher power is n...
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TL;DR: In this paper, the influence of laser entrance hole shields on capsule symmetry and coupling efficiency of an ignition octahedral spherical hohlraum was studied using analytical model and three-dimensional Monte-Carlo simulations.
Abstract: In this paper, the influences of laser entrance hole shields on capsule symmetry and coupling efficiency of an ignition octahedral spherical hohlraum are studied using analytical model and three-dimensional Monte-Carlo simulations. As a result, there are two critical shield radii at which the capsule asymmetry tends to minimum, and the coupling efficiency from hohlraum to capsule reaches its maximum when the shield size is taken around the second critical radius. For the ignition octahedral hohlraums used in our study, the first critical radius is 0.625 mm with a capsule asymmetry of 0.24%, and the second is 0.86 mm with 0.26%, and the asymmetry is smaller than 0.58% for shields’ radius in the range of 0.44 and 0.88 mm, which therefore leaves much flexibility in the shield radius design even the shields have an expansion under radiation ablation. The initial shield radius can be taken around the first critical radius in the ignition target design, not only to have a minimum initial capsule radiation asymmetry, but also to get a minimum asymmetry and highest coupling efficiency during the main pulse of drive. Finally, the relative flux of laser spot, wall and shields is 2.2:1:0.6 for our ignition octahedral spherical hohlraum model from the Monte-Carlo simulations.
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11 Sep 2015
TL;DR: The magnetoresistive heads may include tapered surfaces on the side shields or sensor structure, or may include stepped surfaces in the sensor structure as discussed by the authors, and the distance between side shields and the sensor structures increase in a direction from an ABS in the off-track direction.
Abstract: Embodiments of the present invention generally include magnetoresistive heads, such as read heads, having a sensor structure and side shields disposed adjacent to the sensor structure. The distance between the side shields and the sensor structure increase in a direction from an ABS in the off-track direction. The magnetoresistive heads may include tapered surfaces on the side shields or sensor structure, or may include stepped surfaces on the side shields or sensor structure.
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TL;DR: In this article, the surface radiation and natural convection effects on the heat transfer and flow field between two finite concentric cylinders, using one radiation shield between them, were investigated.
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TL;DR: It is shown that in weak magnetic fields up to 0.5 mT, the output signal amplitude from PMT-85 does not change for all used multilayer shields, and in strong magnetic field of 2-4 m t, theOutput signal amplitude decrease with 10%-40% depending from the number of layers in the shield.
Abstract: Photomultiplier tubes (PMTs) are widely used in physical experiments as well as in applied devices. PMTs are sensitive to magnetic field, so creation of effective magnetic shields for their protection is very important. In this paper, the results of measurements of shielding effectiveness of multilayer film magnetic shields on PMT-85 are presented. Shields were formed by alternating layers of a material with high magnetic permeability (Ni-Fe) and high electric conductivity—Cu. The maximum number of bilayers reached 45. It is shown that in weak magnetic fields up to 0.5 mT, the output signal amplitude from PMT-85 does not change for all used multilayer shields. In strong magnetic field of 2–4 mT, the output signal amplitude decrease with 10%–40% depending from the number of layers in the shield. The Pulse distribution of PMT-85 in magnetic field 0.2–4 mT slightly changed in the range 1.1%–1.3% for the case when the number of layers do not exceed 10 and practically did not change for a shield with 45 double layers.
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TL;DR: In this article, the authors used the finite element method to describe the condition of closing the cable shields at both ends of the cable and solved the problem in two-dimensional formulation.
Abstract: The study tested the process of the magnetic field (MF) mitigation in the HV three-phase power cable lines (CL) made of single core cables in two-ends bonding of their shields. Developed the technique of numerical simulation and calculation of the MF of CL based on its axisymmetric calculation model using the finite element method that allowed to describe the condition of closing the cable shields at the both ends of the CL and solve the problem in two-dimensional formulation. The authors show the possibility of MF mitigation of the three-phase CL by increasing the cross-section of closed cable shields, which in some cases may be an alternative to external electromagnetic shields. Obtained and experimentally validated in laboratory and field conditions with an accuracy of no more than 5 % the value of mitigation coefficients of MF of three-phase three-wire CL in two-ends bonding of their shields depending on the technical parameters of the cables and the geometry of their installation, which is important for the design of new cable power lines. Their values are in the range from 0.99 to 0.32 when the cross sections of cable shields are from 25 mm2 to 200 mm2 and the distance between the axes of the cables are from 0.1 to 0.5 m. The results show the ability to execute design of cable power lines in residential areas, taking into account both the sanitary standards of the MF, as well as to energy efficiency.
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18 Dec 2015TL;DR: In this paper, the effect of the necessary discontinuities on the efficacy of the shields and the design modifications necessary to accommodate the penetrations is assessed. But this work is limited to the case of high temperature superconducting materials.
Abstract: High Temperature Superconducting (HTS) materials have been demonstrated to be suitable for applications in shielding of both DC and AC magnetic fields. Magnetic shielding is required for protecting sensitive instrumentation from external magnetic fields and for preventing the stray magnetic fields produced by high power density equipment from affecting neighbouring devices. HTS shields have high current densities at relatively high operating temperatures (40-77 K) and can be easily fabricated using commercial HTS conductor. High current densities in HTS materials allow design and fabrication of magnetic shields that are lighter and can be incorporated into the body and skin of high power density devices. HTS shields are particularly attractive for HTS devices because a single cryogenic system can be used for cooling the device and the associated shield. Typical power devices need penetrations for power and signal cabling and the penetrations create discontinuities in HTS shields. Hence it is important to assess the effect of the necessary discontinuities on the efficacy of the shields and the design modifications necessary to accommodate the penetrations.
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11 Mar 2015
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TL;DR: This paper proposes an accurate analytical method to estimate the performance of passive thermal shields in the frequency domain, which allows for fast evaluation and optimization and validate the results by comparing them to numerical simulations performed with commercial software based on finite element methods.
Abstract: Modern experiments aiming at tests of fundamental physics, like measuring gravitational waves or testing Lorentz Invariance with unprecedented accuracy, require thermal environments that are highly stable over long times. To achieve such a stability, the experiment including typically an optical resonator is nested in a thermal enclosure, which passively attenuates external temperature fluctuations to acceptable levels. These thermal shields are usually designed using tedious numerical simulations or with simple analytical models. In this paper, we propose an accurate analytical method to estimate the performance of passive thermal shields in the frequency domain, which allows for fast evaluation and optimization. The model analysis has also unveil interesting properties of the shields, such as dips in the transfer function for some frequencies under certain combinations of materials and geometries. We validate the results by comparing them to numerical simulations performed with commercial software based on finite element methods.
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24 Sep 2015TL;DR: A data writer can have at least a write pole separated from first and second side shields by a continuous dielectric gap layer as mentioned in this paper, which increases relative to the sub-layer's distance from the write pole.
Abstract: A data writer can have at least a write pole separated from first and second side shields by a continuous dielectric gap layer. Each side shield may have first and second shield sub-layers configured with different magnetic moments that increase relative to the sub-layer's distance from the write pole. The side shields may wrap around a leading tip of the write pole to form a box shield.
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07 Dec 2015
TL;DR: In this article, the authors proposed a material design using soft and ductile interfaces/adhesive layers to reduce stress wave transmission and the maximum dynamic force, decrease shear deformation of the inner layers behind interfaces, and dissipate more energy due to blast and impact along the armor/shield/helmet surface.
Abstract: Armor/shields/helmets including highly property-mismatched interfaces (mismatch level of bulk materials and interfaces more than 60%) are disclosed, which provide protections against external dynamic loading such as blast loading, impact of projectiles and sharp-edged foreign objects. The mechanism to reduce dynamic force and damage is a specific material design using soft and ductile interfaces/adhesive layers to 1) bond or hold other layers/bulk materials with blast/impact/stab resistance, 2) reduce stress wave transmission and the maximum dynamic force, 3) decrease shear deformation of the inner layers behind interfaces, and 4) dissipate more energy due to blast and impact along the armor/shield/helmet surface. Therefore, less energy would be available to contribute to penetrate the armor/shields/helmets, or cause damage.
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TL;DR: In this article, a method for designing $LC$ tank circuits to improve energy efficiency and reduce layout area is described, which uses a projected shield that is floating, overlaps the trace of the overlying inductor, and adds capacitance to the tank's inductor.
Abstract: A method for designing $LC$ tank circuits to improve energy efficiency and reduce layout area is described. The approach uses a projected shield that is floating, overlaps the trace of the overlying inductor, and adds capacitance to the tank’s inductor. Capacitance is distributed along the spiral traces, and the layout area is thus decreased. In this paper, we investigate the properties of spiral inductors with and without projected shielding, and compare the method with similar circuits including those with floating shields shaped as patterned ground shields. In addition, a measurement methodology for $LC$ tank resonators is developed and presented. Test structures are implemented as microstrip spiral inductors and evaluated as $LC$ tank circuits that resonate between 100 and 500 MHz. The $Q$ values of shielded structures are up to 7% greater than those without shields, and area savings for $LC$ resonators—compared with side-by-side layouts of $L$ and $C$ —are up to 35%.
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TL;DR: In this article, the effect of refurbishment of the heat shields by buffing and subsequently electropolishing was found to improve the performance of the shields as heat reflectors.
Abstract: The use of thermal shields of materials having low emissivity in vacuum furnaces is wellknown. However, the surface condition of the heat shields is one of the most important factors governing their efficiency as radiation resistances. The emissivity of the thermal shields dictates the power rating of the heaters in furnace design. The unpolished materials used in the heater tests showed poor performance leading to loss of a significant percentage of the input power. The present work deals with the refurbishment of the radiation heat shields used in a furnace for heating graphite structure. The effect of refurbishment of the heat shields by the buffing and subsequently electropolishing was found to improve the performance of the shields as heat reflectors. The composition of the electrolyte was chosen in such a way that the large shields of Mo, Inconel and SS can be polished using the same reagents in different ratios. The present work deals with the development of a standard electropolishing procedure for large metallic sheets and subsequently qualifying them by roughness and emissivity measurements. The improvement noted in the shielding efficiency of the furnace in the subsequent runs is also discussed here.
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01 Jan 2015
TL;DR: Grogan et al. as mentioned in this paper used fast neutron tomography to estimate the geometry and materials inside the shielding and then used Monte Carlo simulations to determine the actual enrichment of uranium metal.
Abstract: Oak Ridge National Laboratory is developing a method to estimate the enrichment of uranium metal when heavily shielded by high-Z materials. The method uses fast neutron tomography to estimate the geometry and materials inside the shielding. With the geometry and materials information, the components suspected of being enriched uranium metal are modeled with different enrichments in Monte Carlo simulations. For each modeled enrichment, a simulation predicts the time correlations expected from large fast plastic scintillation detectors following interrogation with a deuterium-tritium neutron generator. The simulated time correlations that best match the measured time correlations are used to determine the actual enrichment. To test the method, time correlation measurements are made on two annular castings that have a 6 in. height, 3.5 in. inner diameter, and 0.75 in. thickness. One casting is 93% enriched, and the other is depleted uranium. Each casting is surrounded by up to three layers of depleted uranium shielding, with each layer being approximately 0.5 in. thick. This paper presents the results of the measurements and compares the results to the simulations. INTRODUCTION Many safeguards and security applications require knowledge and frequent verification of the enrichment of uranium metal items. Under normal circumstances, the items are removed from their containers, and their enrichment is determined using low-energy photons. In some situations, it may be undesirable to remove the items from their containers and/or other shielding. In reference [1], the authors discuss the shortfalls of current methods to determine enrichment when the uranium metal item is surrounded by high-Z materials such that there are no detectable γ-ray emissions. Most methods rely on low-energy photons that are easily shielded by high-Z materials. The authors also present a new method that should work in the presence of shielding materials [1, 2]. The new method involves three primary steps. First, the item and shielding are interrogated with 14 MeV neutrons from a deuterium-tritium (DT) neutron generator (described Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. in the next section of this paper). The neutrons from the generator are time and directionally tagged via the associated particle technique [3]. During the interrogation, an array of small fast plastic scintillation detectors at the same height as the DT generator measures the arrival time of particles relative to the time that the 14 MeV interrogating neutron was created. In addition, an array of eight large fast plastic scintillation detectors located around the item also measures the arrival time of neutrons and γ-rays relative to the 14 MeV neutron creation time. After the measurement, the second step involves creating a tomographic image using the ratio of the response of the small detectors with the item present to the response with no item present. Creation of the tomographic image is discussed elsewhere in the literature [4] and will not be repeated here. The tomographic image shows the neutron attenuation within the item and the shielding, and the arrangement of the item and its shielding as well as the materials present are estimated from the image. Next, the geometry and materials estimates from the tomographic image are input into simulations using MCNP-PoliMi [5] models in order to predict the time response of the large fast plastic detectors. Those regions suspected of being enriched uranium are modeled with several enrichments. Finally, the model whose simulated time response best matches the measured time response of the large detectors yields the estimated enrichment of the item. Many parts of the new method have already been demonstrated or explored with simulations to determine if it will work. Grogan et al. demonstrate estimating the geometry and materials from a tomographic image in reference [6]. Since the neutron attenuation coefficients for 235 U and 238 U are approximately the same, depleted uranium (DU) and highly enriched uranium (HEU) appear the same in a tomographic image. However, the authors have previously presented sensitivity studies with simulations that show that the time signatures for an item and its shielding are unique for differing enrichments [1]. Therefore, if the simulations can accurately predict the time signatures, the method should work. In fact, in a blind test using only simulated data, Swift et al. were able to predict the enrichment of an item when shielded by depleted uranium to within 5 weight percent [7]. To test the ability of simulations to accurately predict the time signatures, measurements of uranium metal with differing enrichments and surrounded with up to ~ 1.5 in. of depleted uranium (DU) were performed at the Y-12 Nuclear Detection and Sensor Testing Center [8] in February 2012. This paper presents the measured time correlations and compares them to initial simulations. EXPERIMENTAL SETUP The two uranium metal items used in the experiment are standard unclassified 161 storage castings used at the Y-12 National Security Complex. The annular castings have a ~6 in. height, 3.50 in. inner diameter, and 0.750 in. thickness. One casting is enriched to 93.186 weight percent 235 U, and the other is DU. The castings have a mass of ~18 kg and are canned inside 0.025 in. thick stainless steel to prevent contamination. Each casting is measured bare and with up to three layers of DU annular shields. The shields are shown in Figure 1, and their dimensions are shown in Table 1. The shields were constructed to allow all three to be used in the same measurement and such that each one weighs approximately 40 lb or less. Like the uranium castings, each shield is canned in 0.025 thick stainless steel to prevent contamination. Figure 1. DU annular shields. Table 1. Dimensions for DU annular shields (not including canning). Shield Inside diameter (in.) Outside diameter (in.) Height (in.) Inner 5.300 6.234 6.999 Middle 6.641 7.394 7.011 Outer 7.789 8.394 7.006 An API-120 DT generator manufactured by Thermo Fisher Scientific is used to interrogate the castings and shields [9]. At maximum power, the generator has an output of 3×10 7 neutrons per second. The generator includes an embedded alpha detector, which ORNL helped develop [10]. A pixelated light guide is attached to the alpha detector followed by a Hamamatsu H9500 photomultiplier tube which provides an array of 16×16 pixels. The system uses one row of 16 3.04 mm square pixels. At maximum power, each pixel records ~5000 α particles per second. Since the α particle produced in the DT reaction travels ~180° from the 14 MeV neutron, the detection of an α in one of the pixels gives both the creation time and direction of the 14 MeV neutron. An array of 32 small fast plastic detectors is located along an arc that is 108.5 cm from the DT generator, as shown in Figure 2. These detectors are used primarily for imaging by detection of neutrons that have passed through the casting without interactions. The dimensions of each detector are 1 in. by 1 in. by 4 in. Pulses from these small imaging detectors are routed to constant fraction discriminators, and the threshold is set such that pulses having less energy than that from the deposition of 1 MeV from a neutron are discarded. The eight large fast plastic detectors in Figure 2 are used primarily to detect neutrons from induced fission in the uranium casting. The dimensions of each detector are 27 by 27 by Inner Shield
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26 Mar 2015
TL;DR: In this article, the authors present a disclosure about touch-screen electronic devices with heat-protective shields on their touch-screens and more particularly to portable touchscreen devices that can be used both indoors and outdoors under conditions of direct sun light and other sources of radiation heat for an extended period of time.
Abstract: Electronic devices with touch-screen displays and methods to make the same. In particular the present disclosure is directed to touch-screen electronic devices with protective heat shields on their touch-screens and more particularly to portable touch-screen devices that can be used both indoors and outdoors under conditions of direct sun light and other sources of radiation heat for an extended period of time. The disclosure also relates to method of applying heat-protective shields on the touch-screen surfaces of such devices.
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TL;DR: In this article, the authors developed a method to determine the minimum indoor air temperature under standby heating using heat-reflective shields in the windows and a multifunctional energy-efficient shutter with solar battery.
Abstract: The new energy saving windows with heat-reflecting shields are well known, but for their practical use they need to be integrated into the automated system for controlling heat supply in buildings and the efficiency of their use tоgether with the existing energy-saving measures must be determined. The study was based on the results of field tests of windows with heat-reflective shields in a certified climate chamber. The method to determine the minimum indoor air temperature under standby heating using heat-reflective shields in the windows and multifunctional energy-efficient shutter with solar battery have been developed. Annual energy saving for the conditions of different regions of Russia and France was determined. Using windows with heat-reflecting screens and a solar battery results in a triple power effect: reduced heat losses during the heating season due to increased window resistance; lower cost of heating buildings due to lowering of indoor ambient temperature; also electric power generation.
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TL;DR: In this article, the Nanomag scintillation telescope was developed and fabricated to protect scientific equipment against both natural and artificial constant magnetic fields in space flight, and the experimental results demonstrated its operability at magnetic field induction to 4 mT.
Abstract: Protection of scientific equipment aboard spacecrafts against both natural and artificial constant magnetic fields is an urgent problem. Multilayer film electromagnetic shields produced by electrodeposition showed high shielding efficiency during laboratory tests. To test their application prospects under conditions of real space flights, a “Nanomag” scintillation telescope was developed and fabricated. Laboratory tests which demonstrated its operability at magnetic field induction to 4 mT are presented in this paper.