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Sample records for electrically self-heated pit

  1. An electrical model of InGaN based high power light emitting diodes with self-heating effect

    NASA Astrophysics Data System (ADS)

    Li, Bingqian; Feng, Yuchun; Liu, Yuhua

    2007-09-01

    We present an electrical model for InGaN based high power light-emitting diodes (LEDs) with self-heating effect. The model consists of an ideal diode connected with a series resistor. Because of the self-heating effect, the temperature of the p-n junction (T j) is much higher than case temperature (T C), the maximum T j in our experiment is 148K high above case temperature. For the T j rises caused by self-heating effect, some temperature-dependent parameters, such as the band gap (E g) of InGaN which influence the reverse saturation current, the hole mobility (μ p) which influence the series resistance of p-type GaN, can be written as the function of forward current (I) and voltage (U). The voltage drops on p-n junction and equivalent series resistance are extracted from the measured I-V curve, and then the values of equivalent series resistance at different forward power are obtained. By the self-heating effect, the values of equivalent series resistance show a very strong forward power-dependent characteristics, the maximum equivalent series resistance in this paper is about 1.6Ωat high forward power, nearly twice of the minimum one. It is worthwhile to point out that the equivalent series resistance changed by self-heating effect and its influence on electronically property of GaN based LEDs can not be neglected even at the low resistance level about 1Ωin our experiment.

  2. On self-heating in piezoresistive microcantilevers with short piezoresistor

    NASA Astrophysics Data System (ADS)

    Zahid Ansari, Mohd; Cho, Chongdu

    2011-07-01

    This work presents an analytical model for studying the effects of short piezoresistors on self-heating phenomena in piezoresistive microcantilevers. The model is verified using commercial finite element software for predicting the temperature profile in the 4-layer silicon dioxide cantilever with silicon piezoresistor commonly used in biosensors. The numerical analysis involved thermo-electric, thermal and surface-stress studies on the cantilever models. Results show good agreement between analytical and numerical results with average deviation about 3%. Further, the temperatures increase more rapidly with the width than the length of the piezoresistor and narrow piezoresistors are helpful in reducing resistance change due to self-heating.

  3. Self-heating properties of coal

    SciTech Connect

    Braun, E.

    1987-08-01

    Three methodologies for predicting the likely occurrence of self-heating in underground coal-mining environments were analyzed. No method was found to be completely satisfactory for general coal-mine applications. One evaluation system was found to provide excellent guidelines for preplanning procedures prior to initiating full-scale coal-mine operations, but it relied on past mining experience. Another evaluation system used standard coal-characterization parameters, while the third system used a thermal-test method as predictor of self-heating potential. The self-heating properties of eight samples of western bituminous coal were determined using the Adiabatic Furnace and the Crossing Point Method. A brief review of pertinent literature is presented to provide an understanding of those factors affecting oxidative heating of coal.

  4. Evaluation of High-Power Solar Electric Propulsion using Advanced Ion, Hall, MPD, and PIT Thrusters for Lunar and Mars Cargo Missions

    NASA Technical Reports Server (NTRS)

    Frisbee, Robert H.

    2006-01-01

    This paper presents the results of mission analyses that expose the advantages and disadvantages of high-power (MWe-class) Solar Electric Propulsion (SEP) for Lunar and Mars Cargo missions that would support human exploration of the Moon and Mars. In these analyses, we consider SEP systems using advanced Ion thrusters (the Xenon [Xe] propellant Herakles), Hall thrusters (the Bismuth [Bi] propellant Very High Isp Thruster with Anode Layer [VHITAL], magnetoplasmadynamic (MPD) thrusters (the Lithium [Li] propellant Advanced Lithium-Fed, Applied-field Lorentz Force Accelerator (ALFA2), and pulsed inductive thruster (PIT) (the Ammonia [NH3] propellant Nuclear-PIT [NuPIT]). The analyses include comparison of the advanced-technology propulsion systems (VHITAL, ALFA2, and NuPIT) relative to state-of-theart Ion (Herakles) propulsion systems and quantify the unique benefits of the various technology options such as high power-per-thruster (and/or high power-per-thruster packaging volume), high specific impulse (Isp), high-efficiency, and tankage mass (e.g., low tankage mass due to the high density of bismuth propellant). This work is based on similar analyses for Nuclear Electric Propulsion (NEP) systems.

  5. Self-heating in piezoresistive cantilevers

    PubMed Central

    Doll, Joseph C.; Corbin, Elise A.; King, William P.; Pruitt, Beth L.

    2011-01-01

    We report experiments and models of self-heating in piezoresistive microcantilevers that show how cantilever measurement resolution depends on the thermal properties of the surrounding fluid. The predicted cantilever temperature rise from a finite difference model is compared with detailed temperature measurements on fabricated devices. Increasing the fluid thermal conductivity allows for lower temperature operation for a given power dissipation, leading to lower force and displacement noise. The force noise in air is 76% greater than in water for the same increase in piezoresistor temperature. PMID:21731884

  6. Localized self-heating in large arrays of 1D nanostructures

    NASA Astrophysics Data System (ADS)

    Monereo, O.; Illera, S.; Varea, A.; Schmidt, M.; Sauerwald, T.; Schütze, A.; Cirera, A.; Prades, J. D.

    2016-02-01

    One dimensional (1D) nanostructures offer a promising path towards highly efficient heating and temperature control in integrated microsystems. The so called self-heating effect can be used to modulate the response of solid state gas sensor devices. In this work, efficient self-heating was found to occur at random networks of nanostructured systems with similar power requirements to highly ordered systems (e.g. individual nanowires, where their thermal efficiency was attributed to the small dimensions of the objects). Infrared thermography and Raman spectroscopy were used to map the temperature profiles of films based on random arrangements of carbon nanofibers during self-heating. Both the techniques demonstrate consistently that heating concentrates in small regions, the here-called ``hot-spots''. On correlating dynamic temperature mapping with electrical measurements, we also observed that these minute hot-spots rule the resistance values observed macroscopically. A physical model of a random network of 1D resistors helped us to explain this observation. The model shows that, for a given random arrangement of 1D nanowires, current spreading through the network ends up defining a set of spots that dominate both the electrical resistance and power dissipation. Such highly localized heating explains the high power savings observed in larger nanostructured systems. This understanding opens a path to design highly efficient self-heating systems, based on random or pseudo-random distributions of 1D nanostructures.One dimensional (1D) nanostructures offer a promising path towards highly efficient heating and temperature control in integrated microsystems. The so called self-heating effect can be used to modulate the response of solid state gas sensor devices. In this work, efficient self-heating was found to occur at random networks of nanostructured systems with similar power requirements to highly ordered systems (e.g. individual nanowires, where their thermal

  7. Localized self-heating in large arrays of 1D nanostructures.

    PubMed

    Monereo, O; Illera, S; Varea, A; Schmidt, M; Sauerwald, T; Schütze, A; Cirera, A; Prades, J D

    2016-03-01

    One dimensional (1D) nanostructures offer a promising path towards highly efficient heating and temperature control in integrated microsystems. The so called self-heating effect can be used to modulate the response of solid state gas sensor devices. In this work, efficient self-heating was found to occur at random networks of nanostructured systems with similar power requirements to highly ordered systems (e.g. individual nanowires, where their thermal efficiency was attributed to the small dimensions of the objects). Infrared thermography and Raman spectroscopy were used to map the temperature profiles of films based on random arrangements of carbon nanofibers during self-heating. Both the techniques demonstrate consistently that heating concentrates in small regions, the here-called "hot-spots". On correlating dynamic temperature mapping with electrical measurements, we also observed that these minute hot-spots rule the resistance values observed macroscopically. A physical model of a random network of 1D resistors helped us to explain this observation. The model shows that, for a given random arrangement of 1D nanowires, current spreading through the network ends up defining a set of spots that dominate both the electrical resistance and power dissipation. Such highly localized heating explains the high power savings observed in larger nanostructured systems. This understanding opens a path to design highly efficient self-heating systems, based on random or pseudo-random distributions of 1D nanostructures. PMID:26868599

  8. Evidence of Universal Temperature Scaling in Self-Heated Percolating Networks.

    PubMed

    Das, Suprem R; Mohammed, Amr M S; Maize, Kerry; Sadeque, Sajia; Shakouri, Ali; Janes, David B; Alam, Muhammad A

    2016-05-11

    During routine operation, electrically percolating nanocomposites are subjected to high voltages, leading to spatially heterogeneous current distribution. The heterogeneity implies localized self-heating that may (self-consistently) reroute the percolation pathways and even irreversibly damage the material. In the absence of experiments that can spatially resolve the current distribution and a nonlinear percolation model suitable to interpret them, one relies on empirical rules and safety factors to engineer these materials. In this paper, we use ultrahigh resolution thermo-reflectance imaging, coupled with a new imaging processing technique, to map the spatial distribution ΔT(x, y; I) and histogram f(ΔT) of temperature rise due to self-heating in two types of 2D networks (percolating and copercolating). Remarkably, we find that the self-heating can be described by a simple two-parameter Weibull distribution, even under voltages high enough to reconfigure the percolation pathways. Given the generality of the phenomenological argument supporting the distribution, other percolating networks are likely to show similar stress distribution in response to sufficiently large stimuli. Furthermore, the spatial evolution of the self-heating of network was investigated by analyzing the spatial distribution and spatial correlation, respectively. An estimation of degree of hotspot clustering reveals a mechanism analogous to crystallization physics. The results should encourage nonlinear generalization of percolation models necessary for predictive engineering of nanocomposite materials. PMID:27070737

  9. Study of novel techniques for reducing self-heating effects in SOI power LDMOS

    NASA Astrophysics Data System (ADS)

    Roig, J.; Flores, D.; Hidalgo, S.; Vellvehi, M.; Rebollo, J.; Millán, J.

    2002-12-01

    Self-heating effects in silicon-on-insulator (SOI) power devices have become a serious problem when the active silicon layer thickness is reduced and buried oxide thickness is increased. Hence, if the temperature of the active region rises, the device electrical characteristics can be seriously modified in steady state and transient modes. In order to alleviate the self heating, two novel techniques which lead to a better heat flow from active silicon layer to silicon substrate through the buried oxide layer in SOI power devices are proposed. No significant changes on device electrical characteristics are expected with the inclusion of the novel techniques. The electro-thermal performance of lateral power devices including the proposed techniques is also presented.

  10. Pitted keratolysis.

    PubMed

    de Almeida, Hiram Larangeira; Siqueira, Rodrigo Nunes; Meireles, Renan da Silva; Rampon, Greice; de Castro, Luis Antonio Suita; Silva, Ricardo Marques E

    2016-01-01

    Pitted keratolysis is a skin disorder that affects the stratum corneum of the plantar surface and is caused by Gram-positive bacteria. A 30-year-old male presented with small punched-out lesions on the plantar surface. A superficial shaving was carried out for scanning electron microscopy. Hypokeratosis was noted on the plantar skin and in the acrosyringium, where the normal elimination of corneocytes was not seen. At higher magnification (x 3,500) bacteria were easily found on the surface and the described transversal bacterial septation was observed. PMID:26982791

  11. Pitted keratolysis*

    PubMed Central

    de Almeida Jr, Hiram Larangeira; Siqueira, Rodrigo Nunes; Meireles, Renan da Silva; Rampon, Greice; de Castro, Luis Antonio Suita; Silva, Ricardo Marques e

    2016-01-01

    Pitted keratolysis is a skin disorder that affects the stratum corneum of the plantar surface and is caused by Gram-positive bacteria. A 30-year-old male presented with small punched-out lesions on the plantar surface. A superficial shaving was carried out for scanning electron microscopy. Hypokeratosis was noted on the plantar skin and in the acrosyringium, where the normal elimination of corneocytes was not seen. At higher magnification (x 3,500) bacteria were easily found on the surface and the described transversal bacterial septation was observed. PMID:26982791

  12. Correction for Self-Heating When Using Thermometers as Heaters in Precision Control Applications

    NASA Technical Reports Server (NTRS)

    Ressler, Michael E.; Cho, Hyung J.; Sukhatme, Kalyani G.

    2011-01-01

    In precision control applications, thermometers have temperature-dependent electrical resistance with germanium or other semiconductor material thermistors, diodes, metal film and wire, or carbon film resistors. Because resistance readout requires excitation current flowing through the sensor, there is always ohmic heating that leads to a temperature difference between the sensing element and the monitored object. In this work, a thermistor can be operated as a thermometer and a heater, simultaneously, by continuously measuring the excitation current and the corresponding voltage. This work involves a method of temperature readout where the temperature offset due to self-heating is subtracted exactly.

  13. Pitted keratolysis (image)

    MedlinePlus

    This picture shows pitted, flesh colored "pits" (keratolysis) or depressions on the soles of the feet, associated with a bad odor (mal-odor). This is thought to be caused by overgrowth of diptheroids ...

  14. Self-heating and failure in scalable graphene devices

    DOE PAGESBeta

    Beechem, Thomas E.; Shaffer, Ryan A.; Nogan, John; Ohta, Taisuke; Hamilton, Allister B.; McDonald, Anthony E.; Howell, Stephen W.

    2016-06-09

    Self-heating induced failure of graphene devices synthesized from both chemical vapor deposition (CVD) and epitaxial means is compared using a combination of infrared thermography and Raman imaging. Despite a larger thermal resistance, CVD devices dissipate >3x the amount of power before failure than their epitaxial counterparts. The discrepancy arises due to morphological irregularities implicit to the graphene synthesis method that induce localized heating. As a result, morphology, rather than thermal resistance, therefore dictates power handling limits in graphene devices.

  15. Self-Heating and Failure in Scalable Graphene Devices

    NASA Astrophysics Data System (ADS)

    Beechem, Thomas E.; Shaffer, Ryan A.; Nogan, John; Ohta, Taisuke; Hamilton, Allister B.; McDonald, Anthony E.; Howell, Stephen W.

    2016-06-01

    Self-heating induced failure of graphene devices synthesized from both chemical vapor deposition (CVD) and epitaxial means is compared using a combination of infrared thermography and Raman imaging. Despite a larger thermal resistance, CVD devices dissipate >3x the amount of power before failure than their epitaxial counterparts. The discrepancy arises due to morphological irregularities implicit to the graphene synthesis method that induce localized heating. Morphology, rather than thermal resistance, therefore dictates power handling limits in graphene devices.

  16. Self-Heating and Failure in Scalable Graphene Devices.

    PubMed

    Beechem, Thomas E; Shaffer, Ryan A; Nogan, John; Ohta, Taisuke; Hamilton, Allister B; McDonald, Anthony E; Howell, Stephen W

    2016-01-01

    Self-heating induced failure of graphene devices synthesized from both chemical vapor deposition (CVD) and epitaxial means is compared using a combination of infrared thermography and Raman imaging. Despite a larger thermal resistance, CVD devices dissipate >3x the amount of power before failure than their epitaxial counterparts. The discrepancy arises due to morphological irregularities implicit to the graphene synthesis method that induce localized heating. Morphology, rather than thermal resistance, therefore dictates power handling limits in graphene devices. PMID:27279020

  17. Self-Heating and Failure in Scalable Graphene Devices

    PubMed Central

    Beechem, Thomas E.; Shaffer, Ryan A.; Nogan, John; Ohta, Taisuke; Hamilton, Allister B.; McDonald, Anthony E.; Howell, Stephen W.

    2016-01-01

    Self-heating induced failure of graphene devices synthesized from both chemical vapor deposition (CVD) and epitaxial means is compared using a combination of infrared thermography and Raman imaging. Despite a larger thermal resistance, CVD devices dissipate >3x the amount of power before failure than their epitaxial counterparts. The discrepancy arises due to morphological irregularities implicit to the graphene synthesis method that induce localized heating. Morphology, rather than thermal resistance, therefore dictates power handling limits in graphene devices. PMID:27279020

  18. Self-heating and drying in two-dimensional bagasse piles

    NASA Astrophysics Data System (ADS)

    Sexton, M. J.; Macaskill, C.; Gray, B. F.

    2001-12-01

    This paper describes a two-dimensional model for self-heating and changes in water levels in bagasse piles of constant rectangular or triangular cross section. (Bagasse is the residue, mainly cellulose, that remains after sugar has been extracted from sugar-cane.) After milling, the bagasse has almost 50% water by weight, as hot water is used to remove the last of the sugar. The bagasse can be used as fuel in electrical power stations, but needs to be dried out before use. This paper discusses the way in which the drying out of a pile depends on the ambient conditions, and the shape and size of the pile. Accordingly, the energy equation, and equations for liquid water, water vapour and oxygen are solved numerically using the method of lines. The equations include terms describing heat conduction, diffusion of water vapour and oxygen, condensation and evaporation and an Arrhenius self-heating term. In addition, recent measurements show that there is also self-heating due to the presence of water in the bagasse, with a maximum effect near 60 °C, which is modelled by a modified Arrhenius expression. The local maximum in the heat release curve for the problem leads to approximate steady-state behaviour on short time scales that eventually is lost as the pile dries out. This interesting physical behaviour motivates an approximate analytical model for the rate at which liquid water is reduced in the pile. Analytical and numerical results are presented for a variety of pile configurations and some fairly general conclusions are drawn.

  19. Self-Heating Effects In Polysilicon Source Gated Transistors

    PubMed Central

    Sporea, R. A.; Burridge, T.; Silva, S. R. P.

    2015-01-01

    Source-gated transistors (SGTs) are thin-film devices which rely on a potential barrier at the source to achieve high gain, tolerance to fabrication variability, and low series voltage drop, relevant to a multitude of energy-efficient, large-area, cost effective applications. The current through the reverse-biased source barrier has a potentially high positive temperature coefficient, which may lead to undesirable thermal runaway effects and even device failure through self-heating. Using numerical simulations we show that, even in highly thermally-confined scenarios and at high current levels, self-heating is insufficient to compromise device integrity. Performance is minimally affected through a modest increase in output conductance, which may limit the maximum attainable gain. Measurements on polysilicon devices confirm the simulated results, with even smaller penalties in performance, largely due to improved heat dissipation through metal contacts. We conclude that SGTs can be reliably used for high gain, power efficient analog and digital circuits without significant performance impact due to self-heating. This further demonstrates the robustness of SGTs. PMID:26351099

  20. Self-heating forecasting for thick laminate specimens in fatigue

    NASA Astrophysics Data System (ADS)

    Lahuerta, F.; Westphal, T.; Nijssen, R. P. L.

    2014-12-01

    Thick laminate sections can be found from the tip to the root in most common wind turbine blade designs. Obtaining accurate and reliable design data for thick laminates is subject of investigations, which include experiments on thick laminate coupons. Due to the poor thermal conductivity properties of composites and the material self-heating that occurs during the fatigue loading, high temperature gradients may appear through the laminate thickness. In the case of thick laminates in high load regimes, the core temperature might influence the mechanical properties, leading to premature failures. In the present work a method to forecast the self-heating of thick laminates in fatigue loading is presented. The mechanical loading is related with the laminate self-heating, via the cyclic strain energy and the energy loss ratio. Based on this internal volumetric heat load a thermal model is built and solved to obtain the temperature distribution in the transient state. Based on experimental measurements of the energy loss factor for 10mm thick coupons, the method is described and the resulting predictions are compared with experimental surface temperature measurements on 10 and 30mm UD thick laminate specimens.

  1. Self-Heating Effects In Polysilicon Source Gated Transistors.

    PubMed

    Sporea, R A; Burridge, T; Silva, S R P

    2015-01-01

    Source-gated transistors (SGTs) are thin-film devices which rely on a potential barrier at the source to achieve high gain, tolerance to fabrication variability, and low series voltage drop, relevant to a multitude of energy-efficient, large-area, cost effective applications. The current through the reverse-biased source barrier has a potentially high positive temperature coefficient, which may lead to undesirable thermal runaway effects and even device failure through self-heating. Using numerical simulations we show that, even in highly thermally-confined scenarios and at high current levels, self-heating is insufficient to compromise device integrity. Performance is minimally affected through a modest increase in output conductance, which may limit the maximum attainable gain. Measurements on polysilicon devices confirm the simulated results, with even smaller penalties in performance, largely due to improved heat dissipation through metal contacts. We conclude that SGTs can be reliably used for high gain, power efficient analog and digital circuits without significant performance impact due to self-heating. This further demonstrates the robustness of SGTs. PMID:26351099

  2. Self-Heating Effects In Polysilicon Source Gated Transistors

    NASA Astrophysics Data System (ADS)

    Sporea, R. A.; Burridge, T.; Silva, S. R. P.

    2015-09-01

    Source-gated transistors (SGTs) are thin-film devices which rely on a potential barrier at the source to achieve high gain, tolerance to fabrication variability, and low series voltage drop, relevant to a multitude of energy-efficient, large-area, cost effective applications. The current through the reverse-biased source barrier has a potentially high positive temperature coefficient, which may lead to undesirable thermal runaway effects and even device failure through self-heating. Using numerical simulations we show that, even in highly thermally-confined scenarios and at high current levels, self-heating is insufficient to compromise device integrity. Performance is minimally affected through a modest increase in output conductance, which may limit the maximum attainable gain. Measurements on polysilicon devices confirm the simulated results, with even smaller penalties in performance, largely due to improved heat dissipation through metal contacts. We conclude that SGTs can be reliably used for high gain, power efficient analog and digital circuits without significant performance impact due to self-heating. This further demonstrates the robustness of SGTs.

  3. Dermoscopy of Pitted Keratolysis

    PubMed Central

    Lockwood, Lauren L.; Gehrke, Samuel; Navarini, Alexander A.

    2010-01-01

    Irritated hyperhidrotic soles with multiple small pits are pathognomonic for pitted keratolysis (PK). Here we show the dermatoscopic view of typical pits that can ensure the diagnosis. PK is a plantar infection caused by Gram-positive bacteria, particularly Corynebacterium. Increases in skin surface pH, hyperhidrosis, and prolonged occlusion allow these bacteria to proliferate. The diagnosis is fundamentally clinical and treatment generally consists of a combination of hygienic measures, correcting plantar hyperhidrosis and topical antimicrobials. PMID:21076687

  4. Self-heating in normal metals and superconductors

    SciTech Connect

    Gurevich, A.V.; Mints, R.G.

    1987-10-01

    This review is devoted to the physics of current-carrying superconductors and normal metals having two or more stable states sustained by Joule self-heating. The creation, propagation, and localization of electrothermal domains and switching waves leading to the transition from one stable state to another in uniform and nonuniform samples are treated in detail. The connection between thermal bistability and hysteresis, dropping and stepped current-voltage characteristics, self-induced oscillations of current and voltage, self-replication of electrothermal domains, and the formation of periodic and stochastic resistive structures are considered.

  5. Optic Nerve Pit

    MedlinePlus

    ... What is the effect of optic pit on vision? The pit itself does not affect vision and most patients remain without any symptoms for decades. About 50% of patients start feeling vision deterioration in their 20’s or 30’s. It is ...

  6. Lithium-ion battery structure that self-heats at low temperatures.

    PubMed

    Wang, Chao-Yang; Zhang, Guangsheng; Ge, Shanhai; Xu, Terrence; Ji, Yan; Yang, Xiao-Guang; Leng, Yongjun

    2016-01-28

    Lithium-ion batteries suffer severe power loss at temperatures below zero degrees Celsius, limiting their use in applications such as electric cars in cold climates and high-altitude drones. The practical consequences of such power loss are the need for larger, more expensive battery packs to perform engine cold cranking, slow charging in cold weather, restricted regenerative braking, and reduction of vehicle cruise range by as much as 40 per cent. Previous attempts to improve the low-temperature performance of lithium-ion batteries have focused on developing additives to improve the low-temperature behaviour of electrolytes, and on externally heating and insulating the cells. Here we report a lithium-ion battery structure, the 'all-climate battery' cell, that heats itself up from below zero degrees Celsius without requiring external heating devices or electrolyte additives. The self-heating mechanism creates an electrochemical interface that is favourable for high discharge/charge power. We show that the internal warm-up of such a cell to zero degrees Celsius occurs within 20 seconds at minus 20 degrees Celsius and within 30 seconds at minus 30 degrees Celsius, consuming only 3.8 per cent and 5.5 per cent of cell capacity, respectively. The self-heated all-climate battery cell yields a discharge/regeneration power of 1,061/1,425 watts per kilogram at a 50 per cent state of charge and at minus 30 degrees Celsius, delivering 6.4-12.3 times the power of state-of-the-art lithium-ion cells. We expect the all-climate battery to enable engine stop-start technology capable of saving 5-10 per cent of the fuel for 80 million new vehicles manufactured every year. Given that only a small fraction of the battery energy is used for self-heating, we envisage that the all-climate battery cell may also prove useful for plug-in electric vehicles, robotics and space exploration applications. PMID:26789253

  7. Lithium-ion battery structure that self-heats at low temperatures

    NASA Astrophysics Data System (ADS)

    Wang, Chao-Yang; Zhang, Guangsheng; Ge, Shanhai; Xu, Terrence; Ji, Yan; Yang, Xiao-Guang; Leng, Yongjun

    2016-01-01

    Lithium-ion batteries suffer severe power loss at temperatures below zero degrees Celsius, limiting their use in applications such as electric cars in cold climates and high-altitude drones. The practical consequences of such power loss are the need for larger, more expensive battery packs to perform engine cold cranking, slow charging in cold weather, restricted regenerative braking, and reduction of vehicle cruise range by as much as 40 per cent. Previous attempts to improve the low-temperature performance of lithium-ion batteries have focused on developing additives to improve the low-temperature behaviour of electrolytes, and on externally heating and insulating the cells. Here we report a lithium-ion battery structure, the ‘all-climate battery’ cell, that heats itself up from below zero degrees Celsius without requiring external heating devices or electrolyte additives. The self-heating mechanism creates an electrochemical interface that is favourable for high discharge/charge power. We show that the internal warm-up of such a cell to zero degrees Celsius occurs within 20 seconds at minus 20 degrees Celsius and within 30 seconds at minus 30 degrees Celsius, consuming only 3.8 per cent and 5.5 per cent of cell capacity, respectively. The self-heated all-climate battery cell yields a discharge/regeneration power of 1,061/1,425 watts per kilogram at a 50 per cent state of charge and at minus 30 degrees Celsius, delivering 6.4–12.3 times the power of state-of-the-art lithium-ion cells. We expect the all-climate battery to enable engine stop–start technology capable of saving 5–10 per cent of the fuel for 80 million new vehicles manufactured every year. Given that only a small fraction of the battery energy is used for self-heating, we envisage that the all-climate battery cell may also prove useful for plug-in electric vehicles, robotics and space exploration applications.

  8. Relative self-heating tendencies of coal, carbonaceous shales, and coal refuse. Report of investigations/1995

    SciTech Connect

    Kim, A.G.

    1995-06-01

    Studies on the initiation and propagation of mine fires have dealt almost exclusively with coal. It has been assumed that the self-heating potential of carbonaceous shales and coal wastes is relatively low. However, in abandoned coal mines and waste banks, initiation and propagation of fires may be strongly dependent on the self-heating tendency of these materials. The purpose of the study was to compare the self-heating probability of carbonaceous shales and coal wastes to that of coals.

  9. TECHNICAL NOTE: A feasibility study of self-heating concrete utilizing carbon nanofiber heating elements

    NASA Astrophysics Data System (ADS)

    Chang, Christiana; Ho, Michelle; Song, Gangbing; Mo, Yi-Lung; Li, Hui

    2009-12-01

    This paper presents the development of an electric, self-heating concrete system that uses embedded carbon nanofiber paper as electric resistance heating elements. The proposed system utilizes the conductive properties of carbon fiber materials to heat a surface overlay of concrete with various admixtures to improve the concrete's thermal conductivity. The development and laboratory scale testing of the system were conducted for the various compositions of concrete containing, separately, carbon fiber, fly ash, and steel shavings as admixtures. The heating performances of these concrete mixtures with the carbon fiber heating element were experimentally obtained in a sub-freezing ambient environment in order to explore the use of such a system for deicing of concrete roadways. Analysis of electric power consumption, heating rate, and obtainable concrete surface temperatures under typical power loads was performed to evaluate the viability of a large scale implementation of the proposed heating system for roadway deicing applications. A cost analysis is presented to provide a comparison with traditional deicing methods, such as salting, and other integrated concrete heating systems.

  10. The Chemistry of Self-Heating Food Products: An Activity for Classroom Engagement

    ERIC Educational Resources Information Center

    Oliver-Hoyo, Maria T.; Pinto, Gabriel; Llorens-Molina, Juan Antonio

    2009-01-01

    Two commercial self-heating food products have been used to apply chemical concepts such as stoichiometry, enthalpies of reactions and solutions, and heat transfer in a classroom activity. These products are the self-heating beverages sold in Europe and the Meals, Ready to Eat or MREs used primarily by the military in the United States. The main…

  11. Ascraeus Mons Collapse Pits

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    We will be looking at collapse pits for the next two weeks. Collapse pits on Mars are formed in several ways. In volcanic areas, channelized lava flows can form roofs which insulate the flowing lava. These features are termed lava tubes on Earth and are common features in basaltic flows. After the lava has drained, parts of the roof of the tube will collapse under its own weight. These collapse pits will only be as deep as the bottom of the original lava tube. Another type of collapse feature associated with volcanic areas arises when very large eruptions completely evacuate the magma chamber beneath the volcano. The weight of the volcano will cause the entire edifice to subside into the void space below it. Structural features including fractures and graben will form during the subsidence. Many times collapse pits will form within the graben. In addition to volcanic collapse pits, Mars has many collapse pits formed when volatiles (such as subsurface ice) are released from the surface layers. As the volatiles leave, the weight of the surrounding rock causes collapse pits to form.

    These collapse pits are found on the flank of Ascraeus Mons. The pits and channels are all related to lava tube formation and emptying.

    Image information: IR instrument. Latitude 8, Longitude 253.9 East (106.1 West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science

  12. Ascraeus Mons Pits

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-482, 13 September 2003

    This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of collapse pits on the northeast flank of the volcano, Ascraeus Mons. These pits are aligned along the trend of faults that are not well exposed at the surface; the faults are concentric to the volcano summit. The image is located near 13.0oN, 103.2oW. This picture covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.

  13. PIT Coating Requirements Analysis

    SciTech Connect

    MINTEER, D.J.

    2000-10-20

    This study identifies the applicable requirements for procurement and installation of a coating intended for tank farm valve and pump pit interior surfaces. These requirements are intended to be incorporated into project specification documents and design media. This study also evaluates previously recommended coatings and identifies requirement-compliant coating products.

  14. Snake bite: pit vipers.

    PubMed

    Peterson, Michael E

    2006-11-01

    Pit vipers are the largest group of venomous snakes in the United States and are involved in an estimated 150,000 bites annually of dogs and cats. The severity of any pit viper bite is related to the volume and toxicity of the venom injected as well as the location of the bite, which may influence the rate of venom uptake. The toxicity of rattlesnake venom varies widely. It is possible for pit vipers' venom to be strictly neurotoxic with virtually no local signs of envenomation. Venom consists of 90% water and has a minimum of 10 enzymes and 3 to 12 nonenzymatic proteins and peptides in any individual snake. The onset of clinical signs after envenomation may be delayed for several hours. The presence of fang marks does not indicate that envenomation has occurred, only that a bite has taken place. Systemic clinical manifestations encompass a wide variety of problems including pain, weakness, dizziness, nausea, severe hypotension, and thrombocytopenia. The victim's clotting abnormalities largely depend upon the species of snake involved. Venom induced thrombocytopenia occurs in approximately 30% of envenomations. Many first aid measures have been advocated for pit viper bite victims, none has been shown to prevent morbidity or mortality. Current recommendations for first aid in the field are to keep the victim calm, keep the bite site below heart level if possible, and transport the victim to a veterinary medical facility for primary medical intervention. The patient should be hospitalized and monitored closely for a minimum of 8 hours for the onset of signs of envenomation. The only proven specific therapy against pit viper envenomation is the administration of antivenin. The dosage of antivenin needed is calculated relative to the amount of venom injected, the body mass of the victim, and the bite site. The average dosage in dogs and cats is 1 to 2 vials of antivenin. PMID:17265901

  15. In situ Measurement of Self-Heating in Intrinsic Tunneling Spectroscopy

    NASA Astrophysics Data System (ADS)

    Krasnov, V. M.; Sandberg, M.; Zogaj, I.

    2005-02-01

    Using advanced sample engineering we performed simultaneous measurements of interlayer tunneling characteristics and in situ monitoring of temperature in Bi2Sr2CaCu2O{8+δ} (Bi-2212) mesas. Together with a systematic study of size dependence of interlayer tunneling, this allowed unambiguous discrimination between artifacts of self-heating and gaps in the electronic spectra of Bi-2212. Such a confident spectroscopic information, which is not affected by self-heating or surface deterioration, was obtained for the first time for a high-Tc superconductor. We also derived general expressions and formulated main principles of self-heating valid for a large variety of materials.

  16. Plasma self-heating and saturation due to numerical instabilities

    SciTech Connect

    Birdsall, C.K.; Maron, N.

    1980-06-01

    The cold-beam nonphysical instability due to the aliases produced by the numerical spatial grid is presented in detail for momentum-conserving linear weighting codes. Additions to previous work include: linear analysis dispersion diagrams showing large growth rates, ..omega../sub i/< or =0.2 ..omega../sub p/; methods for reducing ..omega../sub i/, effectively broadening the finite-size particle width; simulation results verifying the linear theory, plus plots showing the p=1 alias in phase space (..nu../sub x/, x); the growth of beam, thermal spread (..nu../sub t//sup 2/ in temperature) an loss of energy conservation; end-of-growth (saturation at small thermal spread (lambda/sub D//..delta..x=upsilon/sub t//..omega../sub p/..delta..xapprox. =0.046, for lambda/sub B//..delta..xequivalent upsilon/sub 0//..omega../sub p/..delta..x> or =0.3, i.e., upsilon/sub t/< or =0.14upsilon/sub 0/), with return to near energy conservation (stability); demonstration of no growth for a warm beam, with upsilon/sub t/(initial)> or =upsilon/sub t/(saturation); and the mechanism of stabilization (trapping). A thermal (Maxwellian) plasma, also nonphysically unstable at small lambda/sub D//..delta..x, is also found to approach stabilization by self-heating. The two-stream physical instability is affected by the grid, with the aliasing instability also present; the linear theory for this is presented, with guidelines for minimizing the effects of the grid.

  17. Central pit craters on Ganymede

    NASA Astrophysics Data System (ADS)

    Alzate, Nathalia; Barlow, Nadine G.

    2011-02-01

    Central pit craters are common on Mars, Ganymede and Callisto, and thus are generally believed to require target volatiles in their formation. The purpose of this study is to identify the environmental conditions under which central pit craters form on Ganymede. We have conducted a study of 471 central pit craters with diameters between 5 and 150 km on Ganymede and compared the results to 1604 central pit craters on Mars (diameter range 5-160 km). Both floor and summit pits occur on Mars whereas floor pits dominate on Ganymede. Central peak craters are found in similar locations and diameter ranges as central pit craters on Mars and overlap in location and at diameters <60 km on Ganymede. Central pit craters show no regional variations on either Ganymede or Mars and are not concentrated on specific geologic units. Central pit craters show a range of preservation states, indicating that conditions favoring central pit formation have existed since crater-retaining surfaces have existed on Ganymede and Mars. Central pit craters on Ganymede are generally about three times larger than those on Mars, probably due to gravity scaling although target characteristics and resolution also may play a role. Central pits tend to be larger relative to their parent crater on Ganymede than on Mars, probably because of Ganymede's purer ice crust. A transition to different characteristics occurs in Ganymede's icy crust at depths of 4-7 km based on the larger pit-to-crater-diameter relationship for craters in the 70-130-km-diameter range and lack of central peaks in craters larger than 60-km-diameter. We use our results to constrain the proposed formation models for central pits on these two bodies. Our results are most consistent with the melt-drainage model for central pit formation.

  18. Polar Cap Pits

    NASA Technical Reports Server (NTRS)

    2005-01-01

    17 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows kidney bean-shaped pits, and other pits, formed by erosion in a landscape of frozen carbon dioxide. This images shows one of about a dozen different patterns that are common in various locations across the martian south polar residual cap, an area that has been receiving intense scrutiny by the MGS MOC this year, because it is visible on every orbit and in daylight for most of 2005.

    Location near: 86.9oS, 6.9oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  19. Self-heating study of bulk acoustic wave resonators under high RF power.

    PubMed

    Ivira, Brice; Fillit, René-Yves; Ndagijimana, Fabien; Benech, Philippe; Parat, Guy; Ancey, Pascal

    2008-01-01

    The present work first provides an experimental technique to study self-heating of bulk acoustic wave (BAW) resonators under high RF power in the gigahertz range. This study is specially focused on film bulk acoustic wave resonators and solidly mounted resonators processed onto silicon wafers and designed for wireless systems. Precisely, the reflection coefficient of a one-port device is measured while up to several watts are applied and power leads to electrical drifts of impedances. In the following, we describe how absorbed power can be determined from the incident one in real time. Therefore, an infrared camera held over the radio frequency micro electromechanical system (RF-MEMS) surface with an exceptional spatial resolution reaching up to 2 microm/pixels gives accurate temperature mapping of resonators after emissivity correction. From theoretical point of view, accurate three-dimensional (3-D) structures for finite-element modeling analyses are carried out to know the best materials and architectures to use for enhancing power handling. In both experimental and theoretical investigations, comparison is made between film bulk acoustic wave resonators and solidly mounted resonators. Thus, the trend in term of material, architecture, and size of device for power application such as in transmission path of a transceiver is clearly identified. PMID:18334320

  20. Ariel's Densely Pitted Surface

    NASA Technical Reports Server (NTRS)

    1986-01-01

    This mosaic of the four highest-resolution images of Ariel represents the most detailed Voyager 2 picture of this satellite of Uranus. The images were taken through the clear filter of Voyager's narrow-angle camera on Jan. 24, 1986, at a distance of about 130,000 kilometers (80,000 miles). Ariel is about 1,200 km (750 mi) in diameter; the resolution here is 2.4 km (1.5 mi). Much of Ariel's surface is densely pitted with craters 5 to 10 km (3 to 6 mi) across. These craters are close to the threshold of detection in this picture. Numerous valleys and fault scarps crisscross the highly pitted terrain. Voyager scientists believe the valleys have formed over down-dropped fault blocks (graben); apparently, extensive faulting has occurred as a result of expansion and stretching of Ariel's crust. The largest fault valleys, near the terminator at right, as well as a smooth region near the center of this image, have been partly filled with deposits that are younger and less heavily cratered than the pitted terrain. Narrow, somewhat sinuous scarps and valleys have been formed, in turn, in these young deposits. It is not yet clear whether these sinuous features have been formed by faulting or by the flow of fluids.

    JPL manages the Voyager project for NASA's Office of Space Science.

  1. Controlling potential barrier height by changing V-shaped pit size and the effect on optical and electrical properties for InGaN/GaN based light-emitting diodes

    SciTech Connect

    Okada, Narihito Kashihara, Hiroyuki; Sugimoto, Kohei; Yamada, Yoichi; Tadatomo, Kazuyuki

    2015-01-14

    The internal quantum efficiency (IQE) of InGaN/GaN multiple quantum wells (MQWs) with blue light emission was improved by inserting an InGaN/GaN superlattice (SL) beneath the MQWs. While the SL technique is useful for improving the light-emitting diode (LED) performance, its effectiveness from a multilateral point of view requires investigation. V-shaped pits (V-pits), which generate a potential barrier and screen the effect of the threading dislocation, are one of the candidates for increasing the light emission efficiency of LEDs exceptionally. In this research, we investigated the relationship between the V-pit and SL and revealed that the V-pit diameter is strongly correlated with the IQE by changing the number of SL periods. Using scanning near-field optical microscopy and photoluminescence measurements, we demonstrated the distinct presence of the potential barrier formed by the V-pits around the dislocations. The relationship between the V-pit and the number of SL periods resulted in changing the potential barrier height, which is related to the V-pit diameter determined by the number of SL periods. In addition, we made an attempt to insert pit expansion layers (PELs) composed of combination of SL and middle temperature grown GaN layer instead of only SL structure. As a result of the evaluation of LEDs using SL or PEL, the EL intensity was strongly related to pit diameter regardless of the structures to form the V-pits. In addition, it was clear that larger V-pits reduce the efficiency droop, which is considered to be suppression of the carrier loss at high injection current.

  2. 13. DETAIL WEST OF TURBINE PIT SHOWING PIT DRAINED AND ...

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

    13. DETAIL WEST OF TURBINE PIT SHOWING PIT DRAINED AND TURBINE EXPOSED. ORIGINAL WATER LEVEL SHOWN BY LINE JUST ABOVE ARCHED OPENING TO LEFT. WATER LINE AFTER 1982 INSTALLATION OF FLASH BOARDS REVEALED BY DARK STAIN. - Middle Creek Hydroelectric Dam, On Middle Creek, West of U.S. Route 15, 3 miles South of Selinsgrove, Selinsgrove, Snyder County, PA

  3. Ultimate open pit stochastic optimization

    NASA Astrophysics Data System (ADS)

    Marcotte, Denis; Caron, Josiane

    2013-02-01

    Classical open pit optimization (maximum closure problem) is made on block estimates, without directly considering the block grades uncertainty. We propose an alternative approach of stochastic optimization. The stochastic optimization is taken as the optimal pit computed on the block expected profits, rather than expected grades, computed from a series of conditional simulations. The stochastic optimization generates, by construction, larger ore and waste tonnages than the classical optimization. Contrary to the classical approach, the stochastic optimization is conditionally unbiased for the realized profit given the predicted profit. A series of simulated deposits with different variograms are used to compare the stochastic approach, the classical approach and the simulated approach that maximizes expected profit among simulated designs. Profits obtained with the stochastic optimization are generally larger than the classical or simulated pit. The main factor controlling the relative gain of stochastic optimization compared to classical approach and simulated pit is shown to be the information level as measured by the boreholes spacing/range ratio. The relative gains of the stochastic approach over the classical approach increase with the treatment costs but decrease with mining costs. The relative gains of the stochastic approach over the simulated pit approach increase both with the treatment and mining costs. At early stages of an open pit project, when uncertainty is large, the stochastic optimization approach appears preferable to the classical approach or the simulated pit approach for fair comparison of the values of alternative projects and for the initial design and planning of the open pit.

  4. Self-Heating Effects and Analog Performance Optimization of Fin-Type Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Takahashi, Tsunaki; Beppu, Nobuyasu; Chen, Kunro; Oda, Shunri; Uchida, Ken

    2013-04-01

    The self-heating effects (SHEs) of bulk and silicon-on-insulator (SOI) fin-type field-effect transistors (FinFETs) and their impacts on circuit performance have been investigated on the basis of a realistic thermal conductivity of silicon. The heat dissipation via interconnect wires and interface thermal resistance in the high-κ gate stack were incorporated in simulations. It is shown that the depth of the shallow trench isolation (STI) of bulk FinFETs cannot be decreased to less than 100 nm owing to the increase in off-state leakage current. We observed that the thermal resistance Rth of SOI FinFETs greatly decreases upon thinning the buried oxide (BOX) layer. When the BOX thickness tBOX is less than 50 nm, the Rth of SOI FinFETs is smaller than that of bulk FinFETs with an STI thickness of 100 nm, indicating a lower operation temperature of the thin-BOX SOI FinFETs than that of bulk FinFETs. The lower operation temperature of the 5-nm BOX SOI FinFET was confirmed under a practical bias condition for analog operations. In fin width, Wfin, versus Rth characteristics, a strong Wfin dependence of Rth was observed only in the bulk FinFETs, implying that fluctuations in Wfin result in the variability of the operation temperature of the bulk FinFETs. Analog performance has been analyzed by calculating the cutoff frequency fT and the maximum oscillation frequency fmax. We demonstrated that both fT and fmax can be maximized in SOI FinFETs by optimizing tBOX with regard to electrical and thermal properties. Better analog performance, and hence the optimization of tBOX, are indispensable for the device design of a FinFET-based system-on-a-chip (SoC) platform.

  5. Self-heated silicon nanowires for high performance hydrogen gas detection.

    PubMed

    Ahn, Jae-Hyuk; Yun, Jeonghoon; Moon, Dong-Il; Choi, Yang-Kyu; Park, Inkyu

    2015-03-01

    Self-heated silicon nanowire sensors for high-performance, ultralow-power hydrogen detection have been developed. A top-down nanofabrication method based on well-established semiconductor manufacturing technology was utilized to fabricate silicon nanowires in wafer scale with high reproducibility and excellent compatibility with electronic readout circuits. Decoration of palladium nanoparticles onto the silicon nanowires enables sensitive and selective detection of hydrogen gas at room temperature. Self-heating of silicon nanowire sensors allows us to enhance response and recovery performances to hydrogen gas, and to reduce the influence of interfering gases such as water vapor and carbon monoxide. A short-pulsed heating during recovery was found to be effective for additional reduction of operation power as well as recovery characteristics. This self-heated silicon nanowire gas sensor will be suitable for ultralow-power applications such as mobile telecommunication devices and wireless sensing nodes. PMID:25670503

  6. Self-heated silicon nanowires for high performance hydrogen gas detection

    NASA Astrophysics Data System (ADS)

    Ahn, Jae-Hyuk; Yun, Jeonghoon; Moon, Dong-Il; Choi, Yang-Kyu; Park, Inkyu

    2015-03-01

    Self-heated silicon nanowire sensors for high-performance, ultralow-power hydrogen detection have been developed. A top-down nanofabrication method based on well-established semiconductor manufacturing technology was utilized to fabricate silicon nanowires in wafer scale with high reproducibility and excellent compatibility with electronic readout circuits. Decoration of palladium nanoparticles onto the silicon nanowires enables sensitive and selective detection of hydrogen gas at room temperature. Self-heating of silicon nanowire sensors allows us to enhance response and recovery performances to hydrogen gas, and to reduce the influence of interfering gases such as water vapor and carbon monoxide. A short-pulsed heating during recovery was found to be effective for additional reduction of operation power as well as recovery characteristics. This self-heated silicon nanowire gas sensor will be suitable for ultralow-power applications such as mobile telecommunication devices and wireless sensing nodes.

  7. In situ measurement of self-heating in intrinsic tunneling spectroscopy.

    PubMed

    Krasnov, V M; Sandberg, M; Zogaj, I

    2005-02-25

    Using advanced sample engineering we performed simultaneous measurements of interlayer tunneling characteristics and in situ monitoring of temperature in Bi(2)Sr(2)CaCu(2)O(8 + delta) (Bi-2212) mesas. Together with a systematic study of size dependence of interlayer tunneling, this allowed unambiguous discrimination between artifacts of self-heating and gaps in the electronic spectra of Bi-2212. Such a confident spectroscopic information, which is not affected by self-heating or surface deterioration, was obtained for the first time for a high-T(c) superconductor. We also derived general expressions and formulated main principles of self-heating valid for a large variety of materials. PMID:15783844

  8. Comet 67P's Pitted Surface

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-11-01

    High-resolution imagery of comet 67P ChuryumovGerasimenko has revealed that its surface is covered in active pits some measuring hundreds of meters both wide and deep! But what processes caused these pits to form?Pitted LandscapeESAs Rosetta mission arrived at comet 67P in August 2014. As the comet continued its journey around the Sun, Rosetta extensively documented 67Ps surface through high-resolution images taken with the on-board instrument NavCam. These images have revealed that active, circular depressions are a common feature on the comets surface.In an attempt to determine how these pits formed, an international team of scientists led by Olivier Mousis (Laboratory of Astrophysics of Marseille) has run a series of simulations of a region of the comet the Seth region that contains a 200-meter-deep pit. These simulations include the effects of various phase transitions, heat transfer through the matrix of ices and dust, and gas diffusion throughout the porous material.Escaping VolatilesAdditional examples of pitted areas on 67Ps northern-hemisphere surface include the Ash region and the Maat region (both imaged September 2014 by NavCam) [Mousis et al. 2015]Previous studies have already eliminated two potential formation mechanisms for the pits: impacts (the sizes of the pits werent right) and erosion due to sunlight (the pits dont have the right shape). Mousis and collaborators assume that the pits are instead caused by the depletion of volatile materials chemical compounds with low boiling points either via explosive outbursts at the comets surface, or via sinkholes opening from below the surface. But what process causes the volatiles to deplete when the comet heats?The authors simulations demonstrate that volatiles trapped beneath the comets surface either in icy structures called clathrates or within amorphous ice can be suddenly released as the comet warms up. The team shows that the release of volatiles from these two structures can create 200-meter

  9. Tunneling Atomic Force Microscopy Studies on Surface Growth Pits Due to Dislocations in 4H-SiC Epitaxial Layers

    NASA Astrophysics Data System (ADS)

    Ohtani, Noboru; Ushio, Shoji; Kaneko, Tadaaki; Aigo, Takashi; Katsuno, Masakazu; Fujimoto, Tatsuo; Ohashi, Wataru

    2012-08-01

    The morphological and electrical properties of surface growth pits caused by dislocations in 4H-SiC epitaxial layers were characterized using tunneling atomic force microscopy. The characteristic distribution of the tip current between the metal-coated atomic force microscopy tip and the SiC was observed within a large surface growth pit caused by a threading screw dislocation. The current was highly localized inside the pit and occurred only on the inclined surface in the up-step direction near the pit bottom. This paper discusses the causes and possible mechanisms of the observed tip current distribution inside surface growth pits.

  10. 30. (Credit JTL) Old 19111912 low service pump pit and ...

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

    30. (Credit JTL) Old 1911-1912 low service pump pit and receiving well in background. Platform and well in foreground constructed in 1977 for #6 and #7 electric low service pumps (#6 pump moved from old receiving well; #7 installed new). - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  11. Loss effects on adhesively-bonded multilayer ultrasonic transducers by self-heating.

    PubMed

    Wu, Zhengbin; Cochran, Sandy

    2010-04-01

    Multilayer ultrasonic transducers are widely being used for high power applications. In these applications, typical Langevin/Tonpilz structures without any adhesive bondings however have the disadvantage of limited bandwidth. Therefore adhesively-bonded structures are still a potential solution for this issue. In this paper, two-layer piezoelectric ceramic ultrasonic transducers with two different adhesive bondlines were investigated comparing to a single-layer transducer in terms of loss effects during operation with excitation signals sufficient to cause self-heating. The theoretical functions fitted to the measured time-temperature dependency data are compared with experimental results of different piezoelectric transducers. Theoretical analysis of loss characteristics at various surface displacements and the relationship with increasing temperature are reported. The effects of self-heating on the practical performance of multilayer ultrasonic transducers with adhesive bondlines are discussed. PMID:19942247

  12. Self-heating induced instability of oxide thin film transistors under dynamic stress

    NASA Astrophysics Data System (ADS)

    Kise, Kahori; Fujii, Mami N.; Urakawa, Satoshi; Yamazaki, Haruka; Kawashima, Emi; Tomai, Shigekazu; Yano, Koki; Wang, Dapeng; Furuta, Mamoru; Ishikawa, Yasuaki; Uraoka, Yukiharu

    2016-01-01

    Degradation caused by Joule heating of transparent amorphous oxide semiconductor thin-film transistors (TFTs) is an important issue for display technology. Deep understanding of the mechanism of self-heating degradation generated by driving pulse voltage will pave the way for the development of highly reliable flexible displays. In this work, by using a pseudo interval measurement method, we examined the relationship of the highest and the lowest heating temperature in pulse 1 cycle and frequency. These self-heating converged to a constant temperature under pulse voltage applied at 1 kHz. Moreover, the long-term reliability under positive-bias stress voltage at 1 kHz of low converged temperature condition was improved relative to that of the stress voltage at 10 Hz of dynamic temperature change condition. We discussed the degradation mechanism of oxide TFTs generated by pulse voltage, and clarified that the degradation was accelerated by thermionic emission which occurred at low frequency.

  13. OLEDs: light-emitting thin film thermistors revealing advanced self-heating effects

    NASA Astrophysics Data System (ADS)

    Fischer, Axel; Koprucki, Thomas; Glitzky, Annegret; Liero, Matthias; Gärtner, Klaus; Hauptmann, Jacqueline; Reineke, Sebastian; Kasemann, Daniel; Lüssem, Björn; Leo, Karl; Scholz, Reinhard

    2015-09-01

    Large area OLEDs show pronounced Joule self-heating at high brightness. This heating induces brightness inhomogeneities, drastically increasing beyond a certain current level. We discuss this behavior considering 'S'-shaped negative differential resistance upon self-heating, even allowing for 'switched-back' regions where the luminance finally decreases (Fischer et al., Adv. Funct. Mater. 2014, 24, 3367). By using a multi-physics simulation the device characteristics can be modeled, resulting in a comprehensive understanding of the problem. Here, we present results for an OLED lighting panel considered for commercial application. It turns out that the strong electrothermal feedback in OLEDs prevents high luminance combined with a high degree of homogeneity unless new optimization strategies are considered.

  14. Efficient Fabrication of Intrinsic-Josephson-Junction Terahertz Oscillators with Greatly Reduced Self-Heating Effects

    NASA Astrophysics Data System (ADS)

    Kashiwagi, T.; Yamamoto, T.; Minami, H.; Tsujimoto, M.; Yoshizaki, R.; Delfanazari, K.; Kitamura, T.; Watanabe, C.; Nakade, K.; Yasui, T.; Asanuma, K.; Saiwai, Y.; Shibano, Y.; Enomoto, T.; Kubo, H.; Sakamoto, K.; Katsuragawa, T.; Marković, B.; Mirković, J.; Klemm, R. A.; Kadowaki, K.

    2015-11-01

    The intrinsic Josephson junctions (IJJs) in the high-Tc superconductor Bi2Sr2CaCu2O8 +δ (Bi2212) are shown to have great potential for the construction of an oscillator emitting in the terahertz-frequency f regime. However, earlier devices with Bi2212 substrates exhibit strong self-heating effects detrimental to their operation and limiting the maximum f to approximately 1 THz. Here we describe an efficient fabrication procedure for a stand-alone-mesa IJJ terahertz oscillator with considerably reduced self-heating effects, greatly expanding the tunability and maximum value of f , potentially even to 15 THz. Their typical current-voltage characteristics, radiation tunability and power, and some practical uses are also presented.

  15. A numerical and experimental investigation on self-heating effects in viscoelastic dampers

    NASA Astrophysics Data System (ADS)

    de Cazenove, J.; Rade, D. A.; de Lima, A. M. G.; Araújo, C. A.

    2012-02-01

    It is widely known that the mechanical characteristics of viscoelastic materials are highly dependent upon temperature. In traditional procedures of analysis and design of viscoelastic dampers, uniform, constant temperature is generally assumed. However, this procedure can lead to poor designs or even severe failures since the energy dissipated within the volume of the material leads to temperature rises, which depend on a number of factors such as material properties, load conditions and the geometry of the damping device. This phenomenon, which has been frequently disregarded in the literature, is known as self-heating. In this paper, a hybrid numerical-experimental investigation on the self-heating phenomenon in viscoelastic materials subjected to harmonic loadings is reported. The main goal is the development of a finite-element-based methodology intended to perform the thermoviscoelastic analysis of discrete damping devices such as translational and rotational mounts. Since direct coupling between thermal and structural fields would result in prohibitive computational costs, the problem is solved by assuming weak coupling between both fields and the nonlinear coupled thermal and structural analyses are performed in a sequential iterative scheme, implemented in ANSYS™ finite element software. In order to put in evidence the self-heating phenomenon and evaluate the accuracy of the modeling procedure, laboratory experiments are carried-out using a translational viscoelastic mount, subjected to shear harmonic loading with various frequency and amplitude values. The numerical and experimental results obtained in terms of the temperature evolutions at different points within the volume of the viscoelastic material are compared. Additionally, an optimization-based procedure is used to identify some unknown thermal parameters intervening in the model. The obtained results confirm that accounting for self-heating can be of capital importance in the design and

  16. A novel partial SOI LDMOSFET with periodic buried oxide for breakdown voltage and self heating effect enhancement

    NASA Astrophysics Data System (ADS)

    Jamali Mahabadi, S. E.; Rajabi, Saba; Loiacono, Julian

    2015-09-01

    In this paper a partial silicon on insulator (PSOI) lateral double diffused metal oxide semiconductor field effect transistor (LDMOSFET) with periodic buried oxide layer (PBO) for enhancing breakdown voltage (BV) and self-heating effects (SHEs) is proposed for the first time. This new structure is called periodic buried oxide partial silicon on insulator (PBO-PSOI). In this structure, periodic small pieces of SiO2 were used as the buried oxide (BOX) layer in PSOI to modulate the electric field in the structure. It was demonstrated that the electric field is distributed more evenly by producing additional electric field peaks, which decrease the common peaks near the drain and gate junctions in the PBO-PSOI structure. Hence, the area underneath the electric field curve increases which leads to higher breakdown voltage. Also a p-type Si window was introduced in the source side to force the substrate to share the vertical voltage drop, leading to a higher vertical BV. Furthermore, the Si window under the source and those between periodic pieces of SiO2 create parallel conduction paths between the active layer and substrate thereby alleviating the SHEs. Simulations with the two dimensional ATLAS device simulator from the Silvaco suite of simulation tools show that the BV of PBO-PSOI is 100% higher than that of the conventional partial SOI (C-PSOI) structure. Furthermore the PBO-PSOI structure alleviates SHEs to a greater extent than its C-PSOI counterpart. The achieved drain current for the PBO-PSOI structure (100 μA), at drain-source voltage of VDS = 100 V and gate-source voltage of VGS = 25 V, is shown to be significantly larger than that in C-PSOI and fully depleted SOI (FD-SOI) structures (87 μA and 51 μA respectively). Drain current can be further improved at the expense of BV by increasing the doping of the drift region.

  17. Self-heating of dried industrial tannery wastewater sludge induced by pyrophoric iron sulfides formation.

    PubMed

    Bertani, R; Biasin, A; Canu, P; Della Zassa, M; Refosco, D; Simionato, F; Zerlottin, M

    2016-03-15

    Similarly to many powders of solids, dried sludge originated from tannery wastewater may result in a self-heating process, under given circumstances. In most cases, it causes a moderate heating (reaching 70-90°C), but larger, off-design residence times in the drier, in a suboxic atmosphere, extremely reactive solids can be produced. Tannery waste contains several chemicals that mostly end up in the wastewater treatment sludge. Unexpected and uncontrolled self heating could lead to a combustion and even to environmental problems. Elaborating on previous studies, with the addition of several analytical determinations, before and after the self-heating, we attempted to formulate a mechanism for the onset of heating. We demonstrated that the system Fe/S/O has been involved in the process. We proved that the formation of small quantities of pyrophoric iron sulfides is the key. They are converted to sulfated by reaction with water and oxygen with exothermic processes. The pyrite/pyrrhotite production depends on the sludge drying process. The oxidation of sulfides to oxides and sulfates through exothermic steps, reasonably catalyzed by metals in the sludge, occurs preferentially in a moist environment. The mechanism has been proved by reproducing in the laboratory prolonged heating under anoxic/suboxic atmosphere. PMID:26651067

  18. Breaking of Apricot Pits by Using a Mechanical System

    NASA Astrophysics Data System (ADS)

    Polat, R.; Aktas, T.; Gezer, I.; Atay, U.; Bilim, H. I. C.

    The objective of this research was to investigate the effects of heating process and warping effect on breaking of apricot pits and obtaining of its kernel without damage. For this aim, heating process (350°C) was applied to apricot pits. Heated pits were fallen onto the rotating disc and they were warped to warping wall by centrifuge effect. Warping velocity was adjusted by changing of rotating disc revolution that was driven by an electric engine. Three different disc revolution namely 400, 500 and 600 min-1 and 4 different moisture contents of apricot pits namely 6.7, 15.5, 22.2 and 31.5% were used in the experiments. As a result, it was found that increasing of moisture content was increased amount of breaking and also sound kernel ratio. Increasing of disc revolution increased ratio of damaged kernel. The highest breaking amount was determined for experiment with heated pits that had 31.5% moisture content and warped with 400 min-1 disk revolution.

  19. INTERACTIVE PIT LAKES 2004 CONFERENCE

    EPA Science Inventory

    This CD and the workshop provide a pit lakes forum for the exchange of scientific information on current domestic and international approaches, including arid and wet regions throughout the world. These approaches include characterization, modeling/monitoring, and treatment and r...

  20. Numerical Simulation of Temperature Sensor Self-Heating Effects in Gaseous and Liquid Hydrogen Under Cryogenic Conditions

    NASA Astrophysics Data System (ADS)

    Langebach, R.; Haberstroh, Ch.

    2010-04-01

    In this paper a numerical investigation is presented that characterizes the free convective flow field and the resulting heat transfer mechanisms for a resistance temperature sensor in liquid and gaseous hydrogen at various cryogenic conditions. Motivation for this is the detection of stratification effects e.g. inside a liquid hydrogen storage vessel. In this case, the local temperature measurement in still resting fluid requires a very high standard of precision despite an extremely poor thermal anchoring of the sensor. Due to electrical power dissipation a certain amount of heat has to be transferred from sensor to fluid. This can cause relevant measurement errors due to a slightly elevated sensor temperature. A commercial CFD code was employed to calculate the heat and mass transfer around the typical sensor geometry. The results were compared with existing heat transfer correlations from the literature. As a result the magnitude of averaged heat transfer coefficients and sensor over-heating as a function of power dissipation are given in figures. From the gained numerical results a new correlation for the averaged Nusselt Number is presented that represents very low Rayleigh Number flows. The correlation can be used to estimate sensor self-heating effects in similar situations.

  1. Increase of self-heating effects in nanodevices induced by surface roughness: A full-quantum study

    SciTech Connect

    Pala, M. G. Cresti, A.

    2015-02-28

    We present a full-quantum approach to investigate self-heating effects in nanoelectronic devices and exploit it to simulate rough nanowire field-effect transistors. Self-heating is found to significantly contribute (up to about 16%) to the degradation of the transistor performances, with an impact that is stronger for stronger roughness. The mechanism at the origin of the enhanced backscattering is the temperature increase due to the thermal conductivity reduction and the consequent increase of electron-phonon coupling.

  2. Workshop Proceedings: Pitting in Steam Generator Tubing

    SciTech Connect

    1984-10-01

    A two-day workshop focused on the probable causes of steam generator pitting at two nuclear plants and on whether pitting is a low-temperature or a high-temperature phenomenon. Participants also heard descriptions of various pit-resistant metals that are suitable for tube sleeving.

  3. Properties of hydrocarbon- and salt-contaminated flare pit soils in northeastern British Columbia (Canada).

    PubMed

    Arocena, J M; Rutherford, P M

    2005-07-01

    Many contaminated sites in Canada are associated with flare pits generated during past petroleum extraction operations. Flare pits are located adjacent to well sites, compressor stations and batteries and are often subjected to the disposal of wastes from the flaring of gas, liquid hydrocarbons and brine water. This study was conducted to evaluate the physical, chemical, electrical and mineral properties of three flare pit soils as compared to adjacent control soils. Results showed that particle size distribution, pH, total N, cation exchange capacity, exchangeable Mg(2+), and sodium adsorption ratio were similar in soils from flare pits and control sites. Total C, exchangeable Ca(2+), K(+) and Na(+), soluble Ca(2+), Mg(2+), K(+) and Na(+) and electrical conductivity were higher in flare pit soils compared to control soils. X-ray diffraction and scanning electron microscopic analyses showed the presence of gypsum [CaSO(4).2H(2)O], dolomite [CaMg(CO(3))(2)], pyrite [FeS(2)], jarosite [KFe(3)(OH)(6)(SO(4))(2)], magnesium sulphate, oxides of copper and iron+copper in salt efflorescence observed in flare pit soils. Soils from both flare pits and control sites contained mica, kaolonite and 2:1 expanding clays. The salt-rich materials altered the ionic equilibria in the flare pit soils; K(Mg-Ca) selectivity coefficients in control soils were higher compared to contaminated soils. The properties of soils (e.g., high electrical conductivity) affected by inputs associated with oil and gas operations might render flare pit soils less conducive to the establishment and growth of common agricultural crops and forest trees. PMID:15950049

  4. New insights into self-heating in double-gate transistors by solving Boltzmann transport equations

    SciTech Connect

    Thu Trang Nghiêm, T.; Saint-Martin, J.; Dollfus, P.

    2014-08-21

    Electro-thermal effects become one of the most critical issues for continuing the downscaling of electron devices. To study this problem, a new efficient self-consistent electron-phonon transport model has been developed. Our model of phonon Boltzmann transport equation (pBTE) includes the decay of optical phonons into acoustic modes and a generation term given by electron-Monte Carlo simulation. The solution of pBTE uses an analytic phonon dispersion and the relaxation time approximation for acoustic and optical phonons. This coupled simulation is applied to investigate the self-heating effects in a 20 nm-long double gate MOSFET. The temperature profile per mode and the comparison between Fourier temperature and the effective temperature are discussed. Some significant differences occur mainly in the hot spot region. It is shown that under the influence of self-heating effects, the potential profile is modified and both the drain current and the electron ballisticity are reduced because of enhanced electron-phonon scattering rates.

  5. Metal-insulator transition upon heating and negative-differential-resistive-switching induced by self-heating in BaCo{sub 0.9}Ni{sub 0.1}S{sub 1.8}

    SciTech Connect

    Fisher, B.; Genossar, J.; Chashka, K. B.; Patlagan, L.; Reisner, G. M.

    2014-04-14

    The layered compound BaCo{sub 1−x}Ni{sub x}S{sub 2−y} (0.05 < x < 0.2 and 0.05 < y < 0.2) exhibits an unusual first-order structural and electronic phase transition from a low-T monoclinic paramagnetic metal to a high-T tetragonal antiferromagnetic insulator around 200 K with huge hysteresis (∼40 K) and large volume change (∼0.01). Here, we report on unusual voltage-controlled resistive switching followed by current-controlled resistive switching induced by self-heating in polycrystalline BaCo{sub 1−x}Ni{sub x}S{sub 2−y} (nominal x = 0.1 and y = 0.2). These were due to the steep metal to insulator transition upon heating followed by the activated behavior of the resistivity above the transition. The major role of Joule heating in switching is supported by the absence of nonlinearity in the current as function of voltage, I(V), obtained in pulsed measurements, in the range of electric fields relevant to d.c. measurements. The voltage-controlled negative differential resistance around the threshold for switching was explained by a simple model of self-heating. The main difficulty in modeling I(V) from the samples resistance as function of temperature R(T) was the progressive increase of R(T), and to a lesser extend the decrease of the resistance jumps at the transitions, caused by the damage induced by cycling through the transitions by heating or self-heating. This was dealt with by following systematically R(T) over many cycles and by using the data of R(T) in the heating cycle closest to that of the self-heating one.

  6. Pits and Flutes on Stimpy

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The rock 'Stimpy' is seen in this close-up image taken by the Sojourner rover's left front camera on Sol 70 (September 13). Detailed texture on the rock, such as pits and flutes, are clearly visible.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  7. Open pit blasting in India

    SciTech Connect

    Wasson, D.A.; Garg, D.D.

    1995-12-31

    Open pit blasting in India uses two types of explosives. First there are bulk explosives for wet and dry holes, and there are packaged explosives. The Indian open pit coal mining is projected to use 190 thousand metric tons of explosives in 1995. This volume is projected to grow for the next ten years, whereas the underground coal mining will hold fairly constant. Bulk explosives started in about 1977 with watergels. In the late 1980s, bulk emulsions and heavy ANFOs were introduced. This system is still being expanded and is replacing packaged products in the larger mines. Packaged products are still popular where the annual consumption is less than 2,000 metric tons per year. Also, packaged products are used in small wet shots. Porous ammonium nitrate prill have recently become available but ANFO is not very common because of the high cost of the prill and the wet blasting conditions. As the market expands there will be a continuing demand for packaged products but an increasing demand for bulk waterproof products, particularly in the larger operations. Dynamites are produced at four plants in India. The annual production of about 45,000 metric tons per year is holding fairly constant, but is likely to decrease in the future. The future blasting in India will primarily use pumped emulsions and heavy ANFO on an increasing basis, but the packaged products will maintain their position.

  8. Thermal reactive ion etching technique involving use of self-heated cathode

    SciTech Connect

    Yamada, S.; Minami, Y.; Sohgawa, M.; Abe, T.

    2015-04-15

    In this work, the thermal reactive ion etching (TRIE) technique for etching hard-to-etch materials is presented. The TRIE technique employs a self-heated cathode and a thermally insulated aluminum plate is placed on the cathode of a regular reactive ion etching (RIE) system. By optimizing the beam size to support the sample stage, the temperature of the stage can be increased to a desired temperature without a cathode heater. The technique was used to etch a bulk titanium plate. An etch rate of 0.6 μm/min and an etch selectivity to nickel of 100 were achieved with SF{sub 6} plasma. The proposed technique makes a regular RIE system a more powerful etcher without the use of chlorine gas, a cathode heater, and an inductively coupled plasma source.

  9. Thermal reactive ion etching technique involving use of self-heated cathode.

    PubMed

    Yamada, S; Minami, Y; Sohgawa, M; Abe, T

    2015-04-01

    In this work, the thermal reactive ion etching (TRIE) technique for etching hard-to-etch materials is presented. The TRIE technique employs a self-heated cathode and a thermally insulated aluminum plate is placed on the cathode of a regular reactive ion etching (RIE) system. By optimizing the beam size to support the sample stage, the temperature of the stage can be increased to a desired temperature without a cathode heater. The technique was used to etch a bulk titanium plate. An etch rate of 0.6 μm/min and an etch selectivity to nickel of 100 were achieved with SF6 plasma. The proposed technique makes a regular RIE system a more powerful etcher without the use of chlorine gas, a cathode heater, and an inductively coupled plasma source. PMID:25933887

  10. Thermal reactive ion etching technique involving use of self-heated cathode

    NASA Astrophysics Data System (ADS)

    Yamada, S.; Minami, Y.; Sohgawa, M.; Abe, T.

    2015-04-01

    In this work, the thermal reactive ion etching (TRIE) technique for etching hard-to-etch materials is presented. The TRIE technique employs a self-heated cathode and a thermally insulated aluminum plate is placed on the cathode of a regular reactive ion etching (RIE) system. By optimizing the beam size to support the sample stage, the temperature of the stage can be increased to a desired temperature without a cathode heater. The technique was used to etch a bulk titanium plate. An etch rate of 0.6 μm/min and an etch selectivity to nickel of 100 were achieved with SF6 plasma. The proposed technique makes a regular RIE system a more powerful etcher without the use of chlorine gas, a cathode heater, and an inductively coupled plasma source.

  11. Thermal conductivity and diffusivity of biomaterials measured with self-heated thermistors

    NASA Astrophysics Data System (ADS)

    Valvano, J. W.; Cochran, J. R.; Diller, K. R.

    1985-05-01

    This paper presents an experimental method to measure the thermal conductivity and thermal diffusivity of biomaterials. Self-heated thermistor probes, inserted into the tissue of interest, are used to deliver heat as well as to monitor the rate of heat removal. An empirical calibration procedure allows accurate thermal-property measurements over a wide range of tissue temperatures. Operation of the instrument in three media with known thermal properties shows the uncertainty of measurements to be about 2%. The reproducibility is 0.5% for the thermal-conductivity measurements and 2% for the thermal-diffusivity measurements. Thermal properties were measured in dog, pig, rabbit, and human tissues. The tissues included kidney, spleen, liver, brain, heart, lung, pancreas, colon cancer, and breast cancer. Thermal properties were measured for 65 separate tissue samples at 3, 10, 17, 23, 30, 37, and 45°C. The results show that the temperature coefficient of biomaterials approximates that of water.

  12. Comparison between Conduction and Convection Effects on Self-Heating in Doped Microcantilevers

    PubMed Central

    Ansari, Mohd Zahid; Cho, Chongdu

    2012-01-01

    The present study investigates the effects of thermal conduction and convection on self-heating temperatures and bimetallic deflections produced in doped microcantilever sensors. These cantilevers are commonly used as sensors and actuators in microsystems. The cantilever is a monolith, multi-layer structure with a thin U-shaped element inside. The cantilever substrate is made of silicon and silicon dioxide, respectively, and the element is p-doped silicon. A numerical analysis package (ANSYS) is used to study the effect of cantilever substrate material, element width, applied voltage and the operating environments on cantilever characteristics. The numerical results for temperature are compared against their analytical models. Results indicate the numerical results are accurate within 6% of analytical, and Si/Si cantilevers are more suitable for biosensors and AFM, whereas, Si/SiO2 are for hotplates and actuators applications. PMID:22438736

  13. Comparison between conduction and convection effects on self-heating in doped microcantilevers.

    PubMed

    Ansari, Mohd Zahid; Cho, Chongdu

    2012-01-01

    The present study investigates the effects of thermal conduction and convection on self-heating temperatures and bimetallic deflections produced in doped microcantilever sensors. These cantilevers are commonly used as sensors and actuators in microsystems. The cantilever is a monolith, multi-layer structure with a thin U-shaped element inside. The cantilever substrate is made of silicon and silicon dioxide, respectively, and the element is p-doped silicon. A numerical analysis package (ANSYS) is used to study the effect of cantilever substrate material, element width, applied voltage and the operating environments on cantilever characteristics. The numerical results for temperature are compared against their analytical models. Results indicate the numerical results are accurate within 6% of analytical, and Si/Si cantilevers are more suitable for biosensors and AFM, whereas, Si/SiO(2) are for hotplates and actuators applications. PMID:22438736

  14. Measurements and modelling of self-heating in spoil piles from open-cut coal mines

    SciTech Connect

    Carras, J.N.; Saghafi, A.; Bainbridge, N.W.

    1996-12-31

    Open-cut coal mining produces large quantities of spoil. Spoil consists of clays, rock, minerals and other carbonaceous materials (including thin coal seams) which have little or no economic value. When exposed to the elements, in spoil piles, the spoil interacts with water and air as part of the weathering process. Some interactions, for example those involving coal, carbonaceous materials, and pyrite are exothermic. If the rate at which heat is generated within the spoil is greater than the rate at which heat is liberated, the temperature of the spoil rises. If the heating remains unchecked spontaneous combustion can occur. This paper describes the major sources of heat in spoil piles from open cut coal mining and presents laboratory and field measurements of spoil heating. A numerical model of self-heating is described and an example of its use is presented.

  15. Numerical Simulation of the Self-Heating Effect Induced by Electron Beam Plasma in Atmosphere

    NASA Astrophysics Data System (ADS)

    Deng, Yongfeng; Tan, Chang; Han, Xianwei; Tan, Yonghua

    2012-02-01

    For exploiting advantages of electron beam air plasma in some unusual applications, a Monte Carlo (MC) model coupled with heat transfer model is established to simulate the characteristics of electron beam air plasma by considering the self-heating effect. Based on the model, the electron beam induced temperature field and the related plasma properties are investigated. The results indicate that a nonuniform temperature field is formed in the electron beam plasma region and the average temperature is of the order of 600 K. Moreover, much larger volume pear-shaped electron beam plasma is produced in hot state rather than in cold state. The beam ranges can, with beam energies of 75 keV and 80 keV, exceed 1.0 m and 1.2 m in air at pressure of 100 torr, respectively. Finally, a well verified formula is obtained for calculating the range of high energy electron beam in atmosphere.

  16. Conditions of growth of open corrosion pits in stainless steels -- Electrochemical experiments on model pits

    SciTech Connect

    Hakkarainen, T.J.

    1998-12-31

    The effects of the most important variables on continued growth and repassivation of open macroscopic corrosion pits in stainless steel sheets were investigated using two different artificial pit configurations. The pit growth was activated under anodic polarization either by injecting concentrated chloride solution into the pit or by initially filling the pit with chromic chloride crystals (CrCl{sub 3}-6H{sub 2}O). Experiments were made on sheet specimens of stainless steels of type UNS S31603 (316L) or UNS S312.54 in bulk solutions containing chloride and/or sulfate ions. Various aspects of the test arrangements and pitting of stainless steels are discussed, including the electrolyte composition within the pits, repassivation potentials and the IR-drops associated with pit growth. It is demonstrated that using the artificial pit configurations the effects of the main variables affecting the conditions for growth and repassivation of open corrosion pits can be investigated quantitatively, including electrode potentials, temperature, and composition of the bulk solution. It is concluded that for continued growth of corrosion pits with ``large`` openings to the bulk solution, a strongly oxidizing environment is required, and that sulfate ions in amounts comparable to or in excess of that of chloride ions may stabilize pit growth.

  17. Laser-resistance sensitivity to substrate pit size of multilayer coatings

    PubMed Central

    Chai, Yingjie; Zhu, Meiping; Wang, Hu; Xing, Huanbin; Cui, Yun; Sun, Jian; Yi, Kui; Shao, Jianda

    2016-01-01

    Nanosecond laser-resistance to dielectric multilayer coatings on substrate pits was examined with respect to the electric-field (E-field) enhancement and mechanical properties. The laser-induced damage sensitivity to the shape of the substrate pits has not been directly investigated through experiments, thus preventing clear understanding of the damage mechanism of substrate pits. We performed a systematic and comparative study to reveal the effects of the E-field distributions and localized stress concentration on the damage behaviour of coatings on substrates with pits. To obtain reliable results, substrate pits with different geometries were fabricated using a 520-nm femtosecond laser-processing platform. By using the finite element method, the E-field distribution and localized stress of the pitted region were well simulated. The 1064-nm damage morphologies of the coated pit were directly compared with simulated E-field intensity profiles and stress distributions. To enable further understanding, a simplified geometrical model was established, and the damage mechanism was introduced. PMID:27252016

  18. Laser-resistance sensitivity to substrate pit size of multilayer coatings.

    PubMed

    Chai, Yingjie; Zhu, Meiping; Wang, Hu; Xing, Huanbin; Cui, Yun; Sun, Jian; Yi, Kui; Shao, Jianda

    2016-01-01

    Nanosecond laser-resistance to dielectric multilayer coatings on substrate pits was examined with respect to the electric-field (E-field) enhancement and mechanical properties. The laser-induced damage sensitivity to the shape of the substrate pits has not been directly investigated through experiments, thus preventing clear understanding of the damage mechanism of substrate pits. We performed a systematic and comparative study to reveal the effects of the E-field distributions and localized stress concentration on the damage behaviour of coatings on substrates with pits. To obtain reliable results, substrate pits with different geometries were fabricated using a 520-nm femtosecond laser-processing platform. By using the finite element method, the E-field distribution and localized stress of the pitted region were well simulated. The 1064-nm damage morphologies of the coated pit were directly compared with simulated E-field intensity profiles and stress distributions. To enable further understanding, a simplified geometrical model was established, and the damage mechanism was introduced. PMID:27252016

  19. Laser-resistance sensitivity to substrate pit size of multilayer coatings

    NASA Astrophysics Data System (ADS)

    Chai, Yingjie; Zhu, Meiping; Wang, Hu; Xing, Huanbin; Cui, Yun; Sun, Jian; Yi, Kui; Shao, Jianda

    2016-06-01

    Nanosecond laser-resistance to dielectric multilayer coatings on substrate pits was examined with respect to the electric-field (E-field) enhancement and mechanical properties. The laser-induced damage sensitivity to the shape of the substrate pits has not been directly investigated through experiments, thus preventing clear understanding of the damage mechanism of substrate pits. We performed a systematic and comparative study to reveal the effects of the E-field distributions and localized stress concentration on the damage behaviour of coatings on substrates with pits. To obtain reliable results, substrate pits with different geometries were fabricated using a 520-nm femtosecond laser-processing platform. By using the finite element method, the E-field distribution and localized stress of the pitted region were well simulated. The 1064-nm damage morphologies of the coated pit were directly compared with simulated E-field intensity profiles and stress distributions. To enable further understanding, a simplified geometrical model was established, and the damage mechanism was introduced.

  20. 7 CFR 52.807 - Freedom from pits.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CERTAIN OTHER PROCESSED FOOD PRODUCTS 1 United States Standards for Grades of Frozen Red Tart Pitted... medium. (c) (A) Classification. Frozen red tart pitted cherries that are practically free from pits may...) Classification. Frozen red tart pitted cherries that are reasonably free from pits may be given a score of 16...

  1. 7 CFR 52.807 - Freedom from pits.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... CERTAIN OTHER PROCESSED FOOD PRODUCTS 1 United States Standards for Grades of Frozen Red Tart Pitted... medium. (c) (A) Classification. Frozen red tart pitted cherries that are practically free from pits may...) Classification. Frozen red tart pitted cherries that are reasonably free from pits may be given a score of 16...

  2. Speed, Acceleration, Chameleons and Cherry Pit Projectiles

    ERIC Educational Resources Information Center

    Planinsic, Gorazd; Likar, Andrej

    2012-01-01

    The paper describes the mechanics of cherry pit projectiles and ends with showing the similarity between cherry pit launching and chameleon tongue projecting mechanisms. The whole story is written as an investigation, following steps that resemble those typically taken by scientists and can therefore serve as an illustration of scientific…

  3. Competitive Equilibrium and Classroom Pit Markets.

    ERIC Educational Resources Information Center

    Ruffle, Bradley J.

    2003-01-01

    Describes a pit-market experiment using the work of Charles A. Holt to illustrate to students the real world relevance of the competitive equilibrium concept. Explains how to set up and conduct a pit-market experiment, discusses features of the data, and provides accompanying materials. (JEH)

  4. COPPER PITTING AND PINHOLE LEAK RESEARCH STUDY

    EPA Science Inventory

    Localized copper corrosion or pitting is a significant problem at many water utilities across the United States. Copper pinhole leak problems resulting from extensive pitting are widely under reported. Given the sensitive nature of the problem, extent of damage possible, costs o...

  5. Speed, acceleration, chameleons and cherry pit projectiles

    NASA Astrophysics Data System (ADS)

    Planinsic, Gorazd; Likar, Andrej

    2012-01-01

    The paper describes the mechanics of cherry pit projectiles and ends with showing the similarity between cherry pit launching and chameleon tongue projecting mechanisms. The whole story is written as an investigation, following steps that resemble those typically taken by scientists and can therefore serve as an illustration of scientific reasoning and how scientific knowledge is built.

  6. 76 FR 49463 - Pacific Gas and Electric Company; Notice of Authorization for Continued Project Operation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-10

    ... Project Operation On June 16, 2009, Pacific Gas and Electric Company, licensee for the McCloud-Pit... Commission's regulations thereunder. The McCloud-Pit Hydroelectric Project is located on the McCloud and Pit... authorized to continue operation of the McCloud-Pit Hydroelectric Project, until such time as the...

  7. Geophysical Investigations of the Mound City Borrow Pits, Ross County, Ohio

    NASA Astrophysics Data System (ADS)

    Benson, Blair Elizabeth

    Geophysical subsurface imaging is becoming a common practice in archaeology. Non-invasive geophysical methods provide efficient alternatives to costly and invasive excavations, allowing archaeologists to analyze sites before any excavation is done to identify areas of interest. For my thesis, I investigated two prehistoric borrow pits at the Mound City Group (200 BC - 200 AD) in the Hopewell Culture National Historical Park in south-central Ohio. The primary objective of this study was to determine the presence and spatial extent of a clay lining that was emplaced upon the borrow pits by the Hopewell people. Information gleaned from the geophysical investigation was used to assess the degree of site disturbance from agriculture, construction of Camp Sherman, and modern reconstruction of the earthworks. My analysis included a suite of overlapping geophysical surveys consisting of ground-penetrating radar, magnetometry, electromagnetic induction, and electrical resistivity. The geophysical data was ground-truthed with limited auguring and trenching. Analysis of the first borrow pit data showed strong evidence of historical disturbance within the pit from construction of Camp Sherman, including disturbed soil and a buried utility pipe, leaving little of the clay lining present except around the edges of the borrow pit. The geophysical data for the second borrow pit showed less historical damage that was primarily caused from the re-excavation of the pit during the reconstruction of the park. The second borrow pit still retains about half of the clay lining, a finding supported by the results of auguring and trenching. These results are evidence that the borrow pits at Mound City may have also served a purpose as cultural landscape features. The geophysical methods used in this study proved to be an invaluable source of information with minimal disturbance of the site.

  8. The relationship between induction time for pitting and pitting potential for high purity aluminum.

    SciTech Connect

    Wall, Frederick Douglas; Vandenavyle, Justin J.; Martinez, Michael A.

    2003-08-01

    The objective of this study was to determine if a distribution of pit induction times (from potentiostatic experiments) could be used to predict a distribution of pitting potentials (from potentiodynamic experiments) for high-purity aluminum. Pit induction times were measured for 99.99 Al in 50 mM NaCl at potentials of -0.35, -0.3, -0.25, and -0.2 V vs. saturated calomel electrode. Analysis of the data showed that the pit germination rate generally was an exponential function of the applied potential; however, a subset of the germination rate data appeared to be mostly potential insensitive. The germination rate behavior was used as an input into a mathematical relationship that provided a prediction of pitting potential distribution. Good general agreement was found between the predicted distribution and an experimentally determined pitting potential distribution, suggesting that the relationships presented here provide a suitable means for quantitatively describing pit germination rate.

  9. Arne - Exploring the Mare Tranquillitatis Pit

    NASA Astrophysics Data System (ADS)

    Robinson, M. S.; Thangavelautham, J.; Wagner, R.; Hernandez, V. A.; Finch, J.

    2014-12-01

    Lunar mare "pits" are key science and exploration targets. The first three pits were discovered within Selene observations [1,2] and were proposed to represent collapses into lava tubes. Subsequent LROC images revealed 5 new mare pits and showed that the Mare Tranquillitatis pit (MTP; 8.335°N, 33.222°E) opens into a sublunarean void at least 20-meters in extent [3,4]. A key remaining task is determining pit subsurface extents, and thus fully understanding their exploration and scientific value. We propose a simple and cost effective reconnaissance of the MTP using a small lander (<130 kg) named Arne, that carries three flying microbots (or pit-bots) [5,6,7]. Key measurement objectives include decimeter scale characterization of the pit walls, 5-cm scale imaging of the eastern floor, determination of the extent of sublunarean void(s), and measurement of the magnetic and thermal environment. After landing and initial surface systems check Arne will transmit full resolution descent and surface images. Within two hours the first pit-bot will launch and fly into the eastern void. Depending on results from the first pit-bot the second and third will launch and perform follow-up observations. The primary mission is expected to last 48-hours; before the Sun sets on the lander there should be enough time to execute ten flights with each pit-bot. The pit-bots are 30-cm diameter spherical flying robots [5,6,7] equipped with stereo cameras, temperature sensors, sensors for obstacle avoidance and a laser rangefinder. Lithium hydride [5,6] and water/hydrogen peroxide power three micro-thrusters and achieve a specific impulse of 350-400 s. Each pit-bot can fly for 2 min at 2 m/s for more than 100 cycles; recharge time is 20 min. Arne will carry a magnetometer, thermometer, 2 high resolution cameras, and 6 wide angle cameras and obstacle avoidance infrared sensors enabling detailed characterization of extant sublunarean voids. [1] Haruyama et al. (2010) 41st LPSC, #1285. [2

  10. Inertially confined fusion plasmas dominated by alpha-particle self-heating

    NASA Astrophysics Data System (ADS)

    Hurricane, O. A.; Callahan, D. A.; Casey, D. T.; Dewald, E. L.; Dittrich, T. R.; Döppner, T.; Haan, S.; Hinkel, D. E.; Berzak Hopkins, L. F.; Jones, O.; Kritcher, A. L.; Le Pape, S.; Ma, T.; Macphee, A. G.; Milovich, J. L.; Moody, J.; Pak, A.; Park, H.-S.; Patel, P. K.; Ralph, J. E.; Robey, H. F.; Ross, J. S.; Salmonson, J. D.; Spears, B. K.; Springer, P. T.; Tommasini, R.; Albert, F.; Benedetti, L. R.; Bionta, R.; Bond, E.; Bradley, D. K.; Caggiano, J.; Celliers, P. M.; Cerjan, C.; Church, J. A.; Dylla-Spears, R.; Edgell, D.; Edwards, M. J.; Fittinghoff, D.; Barrios Garcia, M. A.; Hamza, A.; Hatarik, R.; Herrmann, H.; Hohenberger, M.; Hoover, D.; Kline, J. L.; Kyrala, G.; Kozioziemski, B.; Grim, G.; Field, J. E.; Frenje, J.; Izumi, N.; Gatu Johnson, M.; Khan, S. F.; Knauer, J.; Kohut, T.; Landen, O.; Merrill, F.; Michel, P.; Moore, A.; Nagel, S. R.; Nikroo, A.; Parham, T.; Rygg, R. R.; Sayre, D.; Schneider, M.; Shaughnessy, D.; Strozzi, D.; Town, R. P. J.; Turnbull, D.; Volegov, P.; Wan, A.; Widmann, K.; Wilde, C.; Yeamans, C.

    2016-08-01

    Alpha-particle self-heating, the process of deuterium-tritium fusion reaction products depositing their kinetic energy locally within a fusion reaction region and thus increasing the temperature in the reacting region, is essential for achieving ignition in a fusion system. Here, we report new inertial confinement fusion experiments where the alpha-particle heating of the plasma is dominant with the fusion yield produced exceeding the fusion yield from the work done on the fuel (pressure times volume change) by a factor of two or more. These experiments have achieved the highest yield (26 +/- 0.5 kJ) and stagnation pressures (≍220 +/- 40 Gbar) of any facility-based inertial confinement fusion experiments, although they are still short of the pressures required for ignition on the National Ignition Facility (~300-400 Gbar). These experiments put us in a new part of parameter space that has not been extensively studied so far because it lies between the no-alpha-particle-deposition regime and ignition.

  11. Co-composting of eggshell waste in self-heating reactors: monitoring and end product quality.

    PubMed

    Soares, Micaela A R; Quina, Margarida M J; Quinta-Ferreira, Rosa M

    2013-11-01

    Industrial eggshell waste (ES) is classified as an animal by-product not intended to human consumption. For reducing pathogen spreading risk due to soil incorporation of ES, sanitation by composting is a pre-treatment option. This work aims to evaluate eggshell waste recycling in self-heating composting reactors and investigate ES effect on process evolution and end product quality. Potato peel, grass clippings and rice husks were the starting organic materials considered. The incorporation of 30% (w/w) ES in a composting mixture did not affect mixture biodegradability, nor its capacity to reach sanitizing temperatures. After 25 days of composting, ES addition caused a nitrogen loss of about 10 g N kg(-1) of initial volatile solids, thus reducing nitrogen nutritional potential of the finished compost. This study showed that a composting mixture with a significant proportion of ES (30% w/w) may be converted into calcium-rich marketable compost to neutralize soil acidity and/or calcium deficiencies. PMID:24055972

  12. MEMS Flow Sensors Based on Self-Heated aGe-Thermistors in a Wheatstone Bridge

    PubMed Central

    Talic, Almir; Cerimovic, Samir; Beigelbeck, Roman; Kohl, Franz; Sauter, Thilo; Keplinger, Franz

    2015-01-01

    A thermal flow transduction method combining the advantages of calorimetric and hot-film transduction principles is developed and analyzed by Finite Element Method (FEM) simulations and confirmed experimentally. The analyses include electrothermal feedback effects of current driven NTC thermistors. Four thin-film germanium thermistors acting simultaneously as heat sources and as temperature sensors are embedded in a micromachined silicon-nitride membrane. These devices form a self-heated Wheatstone bridge that is unbalanced by convective cooling. The voltage across the bridge and the total dissipated power are exploited as output quantities. The used thin-film thermistors feature an extremely high temperature sensitivity. Combined with properly designed resistance values, a power demand in sub-1mW range enables efficient gas-flow transduction, as confirmed by measurements. Two sensor configurations with different arrangements of the membrane thermistors were examined experimentally. Moreover, we investigated the influence of different layouts on the rise time, the sensitivity, and the usable flow range by means of two-dimensional finite element simulations. The simulation results are in reasonable agreement with corresponding measurement data confirming the basic assumptions and modeling approach. PMID:25928062

  13. MEMS Flow Sensors Based on Self-Heated aGe-Thermistors in a Wheatstone Bridge.

    PubMed

    Talic, Almir; Cerimovic, Samir; Beigelbeck, Roman; Kohl, Franz; Sauter, Thilo; Keplinger, Franz

    2015-01-01

    A thermal flow transduction method combining the advantages of calorimetric and hot-film transduction principles is developed and analyzed by Finite Element Method (FEM) simulations and confirmed experimentally. The analyses include electrothermal feedback effects of current driven NTC thermistors. Four thin-film germanium thermistors acting simultaneously as heat sources and as temperature sensors are embedded in a micromachined silicon-nitride membrane. These devices form a self-heated Wheatstone bridge that is unbalanced by convective cooling. The voltage across the bridge and the total dissipated power are exploited as output quantities. The used thin-film thermistors feature an extremely high temperature sensitivity. Combined with properly designed resistance values, a power demand in sub-1mW range enables efficient gas-flow transduction, as confirmed by measurements. Two sensor configurations with different arrangements of the membrane thermistors were examined experimentally. Moreover, we investigated the influence of different layouts on the rise time, the sensitivity, and the usable flow range by means of two-dimensional finite element simulations. The simulation results are in reasonable agreement with corresponding measurement data confirming the basic assumptions and modeling approach. PMID:25928062

  14. Cherry Pit Primes Brad Pitt

    PubMed Central

    Burke, Deborah M.; Locantore, Jill Kester; Austin, Ayda A.; Chae, Bryan

    2008-01-01

    This study investigated why proper names are difficult to retrieve, especially for older adults. On intermixed trials, young and older adults produced a word for a definition or a proper name for a picture of a famous person. Prior production of a homophone (e.g., pit) as the response on a definition trial increased correct naming and reduced tip-of-the-tongue experiences for a proper name (e.g., Pitt) on a picture-naming trial. Among participants with no awareness of the homophone manipulation, older but not young adults showed these homophone priming effects. With a procedure that reduced awareness effects (Experiment 2), prior production of a homophone improved correct naming only for older adults, but speeded naming latency for both age groups. We suggest that representations of proper names are susceptible to weak connections that cause deficits in the transmission of excitation, impairing retrieval especially in older adults. We conclude that homophone production strengthens phonological connections, increasing the transmission of excitation. PMID:15016287

  15. 29. (Credit JTL) Low service pump pit in background erected ...

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

    29. (Credit JTL) Low service pump pit in background erected in 1911-1912 on the banks of Cross Bayou (a Worthington compound duplex steam engine was placed inside this structure.) In the foreground is the receiving well (also erected in 1911-1912) which received water from the Red River siphon. After 1926 this well received water, instead, from Cross Lake via a 30-inch conduit. A concrete platform was installed in 1960 for #6 electric low service pump which has been superceded by newer 1977 installation. - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  16. Okay, Kids, Everyone into the Pit!

    ERIC Educational Resources Information Center

    Belle, Bob; And Others

    1988-01-01

    Discusses a typical food chain and the interrelationship between plants and animals. Describes the "Food Chain Pit" game which can be used to help students create food chains of different habitats. (RT)

  17. Lessons Learned from Pit Viper System Deployment

    SciTech Connect

    Catalan, Michael A.; Bailey, Sharon A.; Alzheimer, James M.; Baker, Carl P.; Valdez, Patrick L.

    2002-08-08

    The Pit Viper is a tele-operated system intended to enhance worker safety while simultaneously improving the efficiency of pit operations at the Hanford Site. Commercial off-the-shelf (COTS) components were used in an attempt to increase system reliability and reduce integration difficulties. The Pit Viper, as is, provides significant improvement over the current baseline approach. During integration, multiple areas where technology development would enhance the effectiveness of the system were identified. Most notable of these areas were the manipulator control system, tool design, and tool handling. Various issues were identified regarding the interfacing of the Pit Viper with the Tank Farm environment and the maturity of remote/ robotic systems for unstructured environments.

  18. Analysis of overall heat balance in self-heated proton-exchange-membrane fuel cells for temperature predictions

    NASA Astrophysics Data System (ADS)

    Koh, Joon-Ho; Hsu, Andrew T.; Akay, Hasan U.; Liou, May-Fun

    The effect of self-heating and cooling by natural convection on a sustainable temperature of PEM fuel cell stacks was studied. Overall mass and heat balance equations are combined to predict self-heated temperatures at various operating conditions. Analyses show that the effect of a heat loss coefficient is more important than other variables such as air flow rate and surrounding temperature. The stack design variables such as active cell area and number of cells also have significant influence on self-controlled temperature. A lower Ohmic resistance of cells is expected to allow a wider range of current load applications. The proposed model can also be used to evaluate heat loss coefficient from measured stack performance and temperature data. Experiments performed on a seven-cell stack of 50 cm 2 active area were used to provide data for the validation of the model.

  19. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2013-01-01 2013-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  20. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2014-01-01 2014-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  1. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2011-01-01 2011-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  2. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2010-01-01 2010-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  3. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2012-01-01 2012-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  4. 7 CFR 52.779 - Freedom from pits.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... one-half pit shell are considered as one-half pit. (2) Drained cherries means pitted cherries that have been drained of packing medium by the method prescribed in this subpart. (c) (A) classification... points. “Practically free from pits” means that the number of pits that may be present in the...

  5. Modeling of light intensification by conical pits within multilayer coatings

    SciTech Connect

    Qiu, S R; Wolfe, J E; Monterrosa, A; Feit, M D; Pistor, T V; Stolz, C J

    2009-11-02

    Removal of laser-induced damage sites provides a possible mitigation pathway to improve damage resistance of coated multilayer dielectric mirrors. In an effort to determine the optimal mitigation geometry which will not generate secondary damage precursors, the electric field distribution within the coating layers for a variety of mitigation shapes under different irradiation angles has been estimated using the finite difference time domain (FDTD) method. The coating consists of twenty-four alternating layers of hafnia and silica with a quarter-wave reflector design. A conical geometrical shape with different cone angles is investigated in the present study. Beam incident angles range from 0{sup o} to 60{sup o} at 5{sup o} increments. We find that light intensification (square of electric field, |E|{sup 2}) within the multilayers depends strongly on the beam incident direction and the cone angle. By comparing the field intensification for each cone angle under all angles of incidence, we find that a 30{sup o} conical pit generates the least field intensification within the multilayer film. Our results suggest that conical pits with shallow cone angles ({le} 30{sup o}) can be used as potential optimal mitigation structures.

  6. Baseline Risk Assessment for the F-Area Burning/Rubble Pits and Rubble Pit

    SciTech Connect

    Palmer, E.

    1996-03-01

    This document provides an overview of the Savannah River Site (SRS) and a description of the F-Area Burning/Rubble Pits (BRPs) and Rubble Pit (RP) unit. It also describes the objectives and scope of the baseline risk assessment (BRA).

  7. NELL-1 increases pre-osteoblast mineralization using both phosphate transporter Pit1 and Pit2

    SciTech Connect

    Cowan, Catherine M.; Zhang, Xinli; James, Aaron W.; Mari Kim, T.; Sun, Nichole; Wu, Benjamin; Ting, Kang; Soo, Chia

    2012-06-08

    Highlights: Black-Right-Pointing-Pointer NELL-1 accelerates extracellular matrix mineralization in MC3T3-E1 pre-osteoblasts. Black-Right-Pointing-Pointer NELL-1 significantly increases intracellular inorganic phosphate levels. Black-Right-Pointing-Pointer NELL-1 positively regulates osteogenesis but not proliferation in MC3T3-E1 cells. Black-Right-Pointing-Pointer NELL-1 regulates inorganic phosphate transporter activity. -- Abstract: NELL-1 is a potent osteoinductive molecule that enhances bone formation in multiple animal models through currently unidentified pathways. In the present manuscript, we hypothesized that NELL-1 may regulate osteogenic differentiation accompanied by alteration of inorganic phosphate (Pi) entry into the osteoblast via sodium dependent phosphate (NaPi) transporters. To determine this, MC3T3-E1 pre-osteoblasts were cultured in the presence of recombinant human (rh)NELL-1 or rhBMP-2. Analysis was performed for intracellular Pi levels through malachite green staining, Pit-1 and Pit-2 expression, and forced upregulation of Pit-1 and Pit-2. Results showed rhNELL-1 to increase MC3T3-E1 matrix mineralization and Pi influx associated with activation of both Pit-1 and Pit-2 channels, with significantly increased Pit-2 production. In contrast, Pi transport elicited by rhBMP-2 showed to be associated with increased Pit-1 production only. Next, neutralizing antibodies against Pit-1 and Pit-2 completely abrogated the Pi influx effect of rhNELL-1, suggesting rhNELL-1 is dependent on both transporters. These results identify one potential mechanism of action for rhNELL-1 induced osteogenesis and highlight a fundamental difference between NELL-1 and BMP-2 signaling.

  8. Project W-314 241-AN-A valve pit upgrade acceptance for beneficial use

    SciTech Connect

    HAMMERS, J.S.

    1999-07-21

    This report identifies the responsibilities and requirements, applicable to the 241-AN-A Valve Pit Upgrades portion of Project W-314, for Acceptance for Beneficial Use in accordance with HNF-IP-0842, Vol IV, Sec 3.12. At project turnover, the end user accepts the affected Structures, Systems, and Components (SSCs) for beneficial use. This checklist is used to help the end user ensure that all documentation, training, and testing requirements are met prior to turnover. This checklist specifically identifies those items related to the upgrading of the 241-AN-A valve pit. The upgrades include: the installation of jumper/valve manifolds with position sensors, replacement pit leak detection systems, construction of replacement cover blocks, and electrical upgrades to support the instrumentation upgrades.

  9. Project W-314 241-AN-B valve pit upgrade acceptance for beneficial use

    SciTech Connect

    HAMMERS, J.S.

    1999-07-21

    This report identifies the responsibilities and requirements, applicable to the 241-AN-B Valve Pit Upgrades portion of Project W-314, for Acceptance for Beneficial Use in accordance with HNF-IP-0842, Vol IV, Sec 3.12. At project turnover, the end user accepts the affected Structures, Systems, and Components (SSCs) for beneficial use. This checklist is used to help the end user ensure that all documentation, training, and testing requirements are met prior to turnover. This checklist specifically identifies those items related to the upgrading of the 241-AN-B valve pit. The upgrades include: the installation of jumper/valve manifolds with position sensors, replacement pit leak detection systems, construction of replacement cover blocks, and electrical upgrades to support the instrumentation upgrades.

  10. Arsia Mons Collapse Pits in IR

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    We will be looking at collapse pits for the next two weeks. Collapse pits on Mars are formed in several ways. In volcanic areas, channelized lava flows can form roofs which insulate the flowing lava. These features are termed lava tubes on Earth and are common features in basaltic flows. After the lava has drained, parts of the roof of the tube will collapse under its own weight. These collapse pits will only be as deep as the bottom of the original lava tube. Another type of collapse feature associated with volcanic areas arises when very large eruptions completely evacuate the magma chamber beneath the volcano. The weight of the volcano will cause the entire edifice to subside into the void space below it. Structural features including fractures and graben will form during the subsidence. Many times collapse pits will form within the graben. In addition to volcanic collapse pits, Mars has many collapse pits formed when volatiles (such as subsurface ice) are released from the surface layers. As the volatiles leave, the weight of the surrounding rock causes collapse pits to form.

    These collapse pits are found on the flank of Arsia Mons and are related to lava tube collapse.

    Image information: IR instrument. Latitude -8.8, Longitude 240.4 East (119.6 West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal

  11. Detection of pits in fresh cherries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are a number of x-ray imaging techniques that could be implemented for the detection of pits in cherries, including linescan and real-time imaging using an image intensifier and CCD camera. However, x-ray imaging equipment is both expensive and bulky, and implementation on the processing line ...

  12. COPPER PITTING CORROSION: A CASE STUDY

    EPA Science Inventory

    Localized or pitting corrosion of copper pipes used in household drinking-water plumbing is a problem for many water utilities and their customers. Extreme attack can lead to pinhole water leaks that may result in water damage, mold growth, and costly repairs. Water quality has b...

  13. Extracting Valuable Data from Classroom Trading Pits

    ERIC Educational Resources Information Center

    Bergstrom, Theodore C.; Kwok, Eugene

    2005-01-01

    How well does competitive theory explain the outcome in experimental markets? The authors examined the results of a large number of classroom trading experiments that used a pit-trading design found in Experiments with Economic Principles, an introductory economics textbook by Bergstrom and Miller. They compared experimental outcomes with…

  14. Global methane emissions from pit latrines.

    PubMed

    Reid, Matthew C; Guan, Kaiyu; Wagner, Fabian; Mauzerall, Denise L

    2014-01-01

    Pit latrines are an important form of decentralized wastewater management, providing hygienic and low-cost sanitation for approximately one-quarter of the global population. Latrines are also major sources of the greenhouse gas methane (CH4) from the anaerobic decomposition of organic matter in pits. In this study, we develop a spatially explicit approach to account for local hydrological control over the anaerobic condition of latrines and use this analysis to derive a set of country-specific emissions factors and to estimate global pit latrine CH4 emissions. Between 2000 and 2015 we project global emissions to fall from 5.2 to 3.8 Tg y(-1), or from ∼ 2% to ∼ 1% of global anthropogenic CH4 emissions, due largely to urbanization in China. Two and a half billion people still lack improved sanitation services, however, and progress toward universal access to improved sanitation will likely drive future growth in pit latrine emissions. We discuss modeling results in the context of sustainable water, sanitation, and hygiene development and consider appropriate technologies to ensure hygienic sanitation while limiting CH4 emissions. We show that low-CH4 on-site alternatives like composting toilets may be price competitive with other CH4 mitigation measures in organic waste sectors, with marginal abatement costs ranging from 57 to 944 $/ton carbon dioxide equivalents (CO2e) in Africa and 46 to 97 $/ton CO2e in Asia. PMID:24999745

  15. OVERVIEW, LOOKING SOUTHWEST, TO 8750 PIT WITH DRILL SETTING AN ...

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

    OVERVIEW, LOOKING SOUTHWEST, TO 8750 PIT WITH DRILL SETTING AN EXPLOSIVE CHARGE TO REMOVE OVERBURDEN AND ACCESS COAL SEAMS LOCATED 200 FEET BELOW FOR STRIPPING. - Drummond Coal Company Cedrum Mine, 8750 Pit, County Road 124, Townley, Walker County, AL

  16. Looking west inside of the soaking pit building for the ...

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

    Looking west inside of the soaking pit building for the 44" slab mill at a red hot ingot being removed from a pit. - U.S. Steel Edgar Thomson Works, 44" Slab Mill, Along Monongahela River, Braddock, Allegheny County, PA

  17. GENERAL OVERVIEW, LOOKING EAST, FROM RECLAIMED PASTURE TO 8750 PIT ...

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

    GENERAL OVERVIEW, LOOKING EAST, FROM RECLAIMED PASTURE TO 8750 PIT WITH STRIPPING AND RECLAMATION ACTIVITY ONGOING SIDE BY SIDE. - Drummond Coal Company Cedrum Mine, 8750 Pit, County Road 124, Townley, Walker County, AL

  18. LONGITUDINAL VIEW OF THE SOAKING PIT BUILDING INTERIOR WITH OPEN ...

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

    LONGITUDINAL VIEW OF THE SOAKING PIT BUILDING INTERIOR WITH OPEN HEARTH IN BACKGROUND AND FURNACE PIT/ STACK AREA TO THE LEFT. - Pittsburgh Steel Company, Monessen Works, Open Hearth Plant, Donner Avenue, Monessen, Westmoreland County, PA

  19. Mosh pits and Circle pits: Collective motion at heavy metal concerts

    NASA Astrophysics Data System (ADS)

    Bierbaum, Matthew; Silverberg, Jesse L.; Sethna, James P.; Cohen, Itai

    2013-03-01

    Heavy metal concerts present an extreme environment in which large crowds (~102 -105) of humans experience very loud music (~ 130 dB) in sync with bright, flashing lights, often while intoxicated. In this setting, we find two types of collective motion: mosh pits, in which participants collide with each other randomly in a manner resembling an ideal gas, and circle pits, in which participants run collectively in a circle forming a vortex of people. We model these two collective behaviors using a flocking model and find qualitative and quantitative agreement with the behaviors found in videos of metal concerts. Futhermore, we find a phase diagram showing the transition from a mosh pit to a circle pit as well as a predicted third phase, lane formation.

  20. Pit Viper strikes at the Hanford site. Pit maintenance using robotics at the Hanford Tank Farms

    SciTech Connect

    Roeder-Smith, Lynne

    2002-06-30

    The Pit Viper - a remote operations waste retrieval system - was developed to replace manual operations in the valve pits of waste storge tanks at the Hanford Site. The system consists of a typical industrial backhoe fitted with a robotic manipulator arm and is operated remotely from a control trailer located outside of the tank farm. Cameras mounted to the arm and within the containment tent allow the operator to view the entire pit area and operate the system using a joystick. The arm's gripper can grasp a variety of tools that allow personnel to perform cleaning, debris removal, and concrete repair tasks -- a more efficient and less dose-intensive process than the previous "long-pole" method. The project team overcame a variety of obstacles during development and testing of the Pit Viper system, and deployment occurred in Hanford Tank C-104 in December 2001.

  1. Thermal analysis of simulated Pantex pit storage

    SciTech Connect

    Aceves, S.M., Kornblum, B.T.

    1996-10-01

    This report investigates potential pit storage configurations that could be used at the Mason and Hanger Pantex Plant. The study utilizes data from a thermal test series performed at Lawrence Livermore National Laboratory (LLNL) that simulated these storage configurations. The heat output values used in the LLNL test series do not represent actual pits but are rounded numbers that were chosen for convenience to allow parameter excursions. Specifically in this project, we are modeling the heat transfer and air flow around cylindrical storage containers in Pantex magazines in order to predict container temperatures. This difficult problem in thermal- fluid mechanics involves transient, three-dimensional (3-D) natural convection and thermal radiation around interacting containers with various heat generation rates. Our approach is to link together two computational methods in order to synthesize a modeling procedure for a large array of pit storage containers. The approach employs a finite element analysis of a few containers, followed by a lumped- parameter model of an array of containers. The modeling procedure we developed was applied in the simulation of a recent experiment where temperatures of pit storage containers were monitored in a steady- state, controlled environment. Our calculated pit container temperatures are comparable with data from that experiment. We found it absolutely necessary to include thermal radiation between containers in order to predict temperatures accurately, although the assumption of black-body radiation appears to be sufficient. When radiation is neglected the calculated temperatures are 4 to 6 {degrees}C higher than temperature data from the experiment. We also investigated our model`s sensitivity to variations in the natural convection heat transfer coefficient and found that with a 50% drop in the coefficient, calculated temperatures are approximately I {degree}C higher. Finally, with a modified lumped-parameter model, we

  2. An investigation of the self-heating phenomenon in viscoelastic materials subjected to cyclic loadings accounting for prestress

    NASA Astrophysics Data System (ADS)

    de Lima, A. M. G.; Rade, D. A.; Lacerda, H. B.; Araújo, C. A.

    2015-06-01

    It has been demonstrated by many authors that the internal damping mechanism of the viscoelastic materials offers many possibilities for practical engineering applications. However, in traditional procedures of analysis and design of viscoelastic dampers subjected to cyclic loadings, uniform, constant temperature is generally assumed and do not take into account the self-heating phenomenon. Moreover, for viscoelastic materials subjected to dynamic loadings superimposed on static preloads, such as engine mounts, these procedures can lead to poor designs or even severe failures since the energy dissipated within the volume of the material leads to temperature rises. In this paper, a hybrid numerical-experimental investigation of effects of the static preloads on the self-heating phenomenon in viscoelastic dampers subjected to harmonic loadings is reported. After presenting the theoretical foundations, the numerical and experimental results obtained in terms of the temperature evolutions at different points within the volume of the viscoelastic material for various static preloads are compared, and the main features of the methodology are discussed.

  3. A Study on Self-Heating and Mutual Thermal Coupling in SiGe Multi-Finger HBTs

    NASA Astrophysics Data System (ADS)

    Dwivedi, A. D. D.; D'Esposito, Rosario; Sahoo, Amit Kumar; Fregonese, Sebastien; Zimmer, Thomas

    2016-07-01

    In this paper, the self-heating and mutual thermal coupling in a state-of-the-art SiGe:C multi-finger heterojunction bipolar transistor (HBT) was investigated in static dc operation conditions. Multi-finger HBT structure was created using Sentaurus structure editor with dimensions similar to the layout of SiGe:C multi-finger HBTs in ST-Microelectronics BiCMOS55 (B55) technology (f T > 300 GHz, f max > 400 GHz) as per ST's BiCMOS55 process design kit guidelines. Three-dimensional thermal technology computer aided design (TCAD) simulations were carried out to obtain the temperature distribution in static dc operation. The lattice temperature (T Lattice) and heat flux (F Heat) distribution inside the device were studied. The impact of back-end-of-line (BEOL) layers on static thermal behavior of the state-of-the-art SiGe:C multi finger HBTs was also investigated. The temperature dependent thermal resistance of different fingers of the trench isolated SiGe multi-finger HBT was extracted without and with back-end-of-line (BEOL) effect. An electro-thermal dc compact model of self-heating and mutual thermal coupling in multi-finger HBTs was proposed and applied to compare the modeling results with the TCAD simulation results. Very good agreement was achieved between results obtained from TCAD simulation and those obtained from compact model-based simulation.

  4. 30 CFR 56.3131 - Pit or quarry wall perimeter.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Pit or quarry wall perimeter. 56.3131 Section... Mining Methods § 56.3131 Pit or quarry wall perimeter. In places where persons work or travel in... stripped back for at least 10 feet from the top of the pit or quarry wall. Other conditions at or near...

  5. 30 CFR 56.3131 - Pit or quarry wall perimeter.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Pit or quarry wall perimeter. 56.3131 Section... Mining Methods § 56.3131 Pit or quarry wall perimeter. In places where persons work or travel in... stripped back for at least 10 feet from the top of the pit or quarry wall. Other conditions at or near...

  6. 30 CFR 56.3131 - Pit or quarry wall perimeter.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Pit or quarry wall perimeter. 56.3131 Section... Mining Methods § 56.3131 Pit or quarry wall perimeter. In places where persons work or travel in... stripped back for at least 10 feet from the top of the pit or quarry wall. Other conditions at or near...

  7. 30 CFR 56.3131 - Pit or quarry wall perimeter.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Pit or quarry wall perimeter. 56.3131 Section... Mining Methods § 56.3131 Pit or quarry wall perimeter. In places where persons work or travel in... stripped back for at least 10 feet from the top of the pit or quarry wall. Other conditions at or near...

  8. 30 CFR 56.3131 - Pit or quarry wall perimeter.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Pit or quarry wall perimeter. 56.3131 Section... Mining Methods § 56.3131 Pit or quarry wall perimeter. In places where persons work or travel in... stripped back for at least 10 feet from the top of the pit or quarry wall. Other conditions at or near...

  9. 99. ARAIII. Overall view of drilling area in reactor pit. ...

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

    99. ARA-III. Overall view of drilling area in reactor pit. Bridge over pit in use for operations. Shows water in pool, reactor, hoist, operators, and general view of interior of reactor pit area. August 12, 1963. Ineel photo no. 63-4454. Photographer: Benson. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

  10. Metastable pitting of carbon steel under potentiostatic control

    SciTech Connect

    Cheng, Y.F.; Luo, J.L.

    1999-03-01

    The metastable pitting of A516-70 carbon steel was studied under potentiostatic control in solutions containing chloride ions. It was shown that there were different current fluctuation patterns and spectral slopes, that is, roll-off slopes, in passivity, general corrosion, and metastable pitting. Pits were often covered by a deposit which played an important role in the current fluctuation, with a quick current rise followed by a slow drop. There was a transitional potential (about 0 mV vs Ag/AgCl electrode) below which the metastable pitting initiation rate increased with the potential, because more sites would be activated. Above the transitional potential, the decay of the pitting occurrence rate with increased potential was due to the elimination of available pit sites. When the applied potential was between {minus}50 and 100 mV, pit growth kinetics was controlled by the potential drop through the deposit over the pit mouth. The potential dependence of repassivation time was mainly due to the effect of applied potential on the deposit over the pit mouth. There seemed to be good agreement between the calculated pit size and the measured values by optical microphotography. The assumption of hemispherical pit geometry was reasonable in calculating the pit radii.

  11. 10. Turbine Pit of Unit 5, view to the north. ...

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

    10. Turbine Pit of Unit 5, view to the north. Note the difference in configuration within this turbine pit as compared to one of the original pits illustrated in photograph number MT-105-A-11. - Washington Water Power Clark Fork River Noxon Rapids Hydroelectric Development, Powerhouse, South bank of Clark Fork River at Noxon Rapids, Noxon, Sanders County, MT

  12. THE INFLUENCE OF NANOENGINEERED Cu DEFECTS ON ALUMINUM PITTING INITIATION

    SciTech Connect

    WALL,F.D.; SON,K.A.; MISSERT,N.A.; BARBOUR,J.C.; MARTINEZ,M.A.; ZAVIDIL,K.R.; SULLIVAN,J.P.; GOPELAND,R.G.; CIESLAK,W.R.; BUCHHEIT,R.G.; ISAACS,H.S.

    1999-11-01

    Nanoengineering technologies have been used to generate well defined arrays of pure Cu islands within an Al thin film matrix in order to examine the impact of noble particle defects on the initiation of metastable pitting. The Cu particles form local galvanic cells with the surrounding Al matrix and drive metastable corrosion. Electrical isolation of the Cu particles from the Al occurs due to selective Al dissolution and appears to correlate to cessation of metastable events. Distributions of parameters related to the electrochemical signature of an event suggests that size and spacing of particles do not impact the signatures of individual events. However, event frequency data indicate that the propensity for a structure to induce localized events is linked to Cu island diameter and separation.

  13. Corrosion pitting of SiC by molten salts

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.; Smialek, J. L.

    1986-01-01

    The corrosion of SiC by thin films of Na2CO3 and Na2SO4 at 1000 C is characterized by a severe pitting attack of the SiC substrate. A range of different Si and SiC substrates were examined to isolate the factors critical to pitting. Two types of pitting attack are identified: attack at structural discontinuities and a crater-like attack. The crater-like pits are correlated with bubble formation during oxidation of the SiC. It appears that bubbles create unprotected regions, which are susceptible to enhanced attack and, hence, pit formation.

  14. Analysis of BY-106 pump pit cover plate

    SciTech Connect

    Coverdell, B.L.

    1994-11-14

    A new cover for the pump pit of Tank 241-BY-106 has been designed to allow the rotary core exhauster to be hooked up without requiring pit entry, riser modification, or equipment removal. The new pit cover is necessary to allow installation of two risers for reducing exposure, contamination, and waste. Computer analysis indicates that the safety margin of the pit cover plate with two risers is adequate. The computer stress model and input files are attached. The pit cover plate is a replacement for an existing plate; therefore seismic and wind loads were considered for the plate only.

  15. Treatment of a mud pit by bioremediation.

    PubMed

    Avdalović, Jelena; Đurić, Aleksandra; Miletić, Srdjan; Ilić, Mila; Milić, Jelena; Vrvić, Miroslav M

    2016-08-01

    The mud generated from oil and natural gas drilling, presents a considerable ecological problem. There are still insufficient remedies for the removal and minimization of these very stable emulsions. Existing technologies that are in use, more or less successfully, treat about 20% of generated waste drilling mud, while the rest is temporarily deposited in so-called mud pits. This study investigated in situ bioremediation of a mud pit. The bioremediation technology used in this case was based on the use of naturally occurring microorganisms, isolated from the contaminated site, which were capable of using the contaminating substances as nutrients. The bioremediation was stimulated through repeated inoculation with a zymogenous microbial consortium, along with mixing, watering and biostimulation. Application of these bioremediation techniques reduced the concentration of total petroleum hydrocarbons from 32.2 to 1.5 g kg(-1) (95% degradation) during six months of treatment. PMID:27354013

  16. EPA tightens enforcement on use of unlined pits

    SciTech Connect

    Not Available

    1992-10-19

    This paper reports that the U.S. Environmental Protection Agency has ordered Texaco Inc. To close all of its unlined pits that may endanger surface or ground water quality on Navajo Indian acreage in three western states. Estimated at 200 in number, Texaco's pits have been used to discharge oil and gas waste products, EPA the. An EPA sampling of fluid discharged to Texaco's pits showed high levels of benzene, ethylbenzene, and toluene. The order requires Texaco to develop a plan to remove and dispose of pit fluids, take soil samples from under the pits, describe how contaminated soil will be removed or remediated, and describe how the pits will be filled or permanently sealed. Texaco also is required to develop a plant to test water supply wells for pollutants within a 1/2 mile radius of the pits.

  17. Pitting corrosion resistant austenite stainless steel

    DOEpatents

    van Rooyen, D.; Bandy, R.

    A pitting corrosion resistant austenite stainless steel comprises 17 to 28 wt. % chromium, 15 to 26 wt. % nickel, 5 to 8 wt. % molybdenum, and 0.3 to 0.5 wt. % nitrogen, the balance being iron, unavoidable impurities, minor additions made in the normal course of melting and casting alloys of this type, and may optionally include up to 10 wt. % of manganese, up to 5 wt. % of silicon, and up to 0.08 wt. % of carbon.

  18. Chain of Pits on Pavonis Mons

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Pavonis Mons is the middle of the three large Tharsis Montes volcanoes in the martian western hemisphere. Located on the equator at about 113oW longitude, Pavonis Mons stands as much as 7 kilometers (4 miles) above the surrounding plain. The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) recently spied the above chain of elliptical pits on the lower east flank of Pavonis Mons. The picture covers an area 3 kilometers (1.9 miles) wide by 3.4 kilometers (2.1 miles) in length. The pits are aligned down the center of a 485 meters-(530 yards)-wide, shallow trough. The straight trough and the pits were both formed by collapse associated with faulting. The scarp on each side of the trough is a fault line--troughs of this type are known to geologists as graben. Such features are typically formed when the ground is being moved apart by tectonic forces, or when the ground is uplifted by molten rock injected into the near sub-surface from deeper underground. Both processes may be contributing to the features seen on Pavonis Mons. The pits follow the trend of these faults, and indicate the locus of collapse. Illumination is from the upper left in this image.

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  19. Slag pit practices to improve slag quality

    SciTech Connect

    Mertdogan, A.; Gambol, F.C.; Spaeth, J.R.; Zbos, J.; Batka, R.; Tolliver, D.

    1996-12-31

    Slag quality had deteriorated recently. Without the explicit approval for slag quality by the Illinois Department of Transportation, the slag would not be saleable. Disposal of slag to landfills was going to be an expensive solution and rife with environmental concerns. A slag quality control program embarked on in mid-1994 restored slag quality to desired specifications. This paper describes the changes in slag pit practice adopted following extensive tests performed on cooling slag under controlled conditions.

  20. Constituent Particle Clustering and Pitting Corrosion

    NASA Astrophysics Data System (ADS)

    Harlow, D. Gary

    2012-08-01

    Corrosion is a primary degradation mechanism that affects the durability and integrity of structures made of aluminum alloys, and it is a concern for commercial transport and military aircraft. In aluminum alloys, corrosion results from local galvanic coupling between constituent particles and the metal matrix. Due to variability in particle sizes, spatial location, and chemical composition, to name a few critical variables, corrosion is a complex stochastic process. Severe pitting is caused by particle clusters that are located near the material surface, which, in turn, serve as nucleation sites for subsequent corrosion fatigue crack growth. These evolution processes are highly dependent on the spatial statistics of particles. The localized corrosion growth rate is primarily dependent on the galvanic process perpetuated by particle-to-particle interactions and electrochemical potentials. Frequently, severe pits are millimeters in length, and these pits have a dominant impact on the structural prognosis. To accommodate large sizes, a model for three-dimensional (3-D) constituent particle microstructure is proposed. To describe the constituent particle microstructure in three dimensions, the model employs a fusion of classic stereological techniques, spatial point pattern analyses, and qualitative observations. The methodology can be carried out using standard optical microscopy and image analysis techniques.

  1. Pits, pipes, ponds--and me.

    PubMed

    Mara, Duncan

    2013-05-01

    My life in low-cost sanitation and low-cost wastewater treatment and the use of treated wastewater in agriculture and aquaculture really has been 'pits, pipes and ponds' - 'pits' are low-cost sanitation technologies (LCST) such as VIP latrines and pour-flush toilets; 'pipes' are low-cost sewerage, principally condominial (simplified) sewerage; and 'ponds' are low-cost wastewater treatment systems, especially waste stabilization ponds, and the use of treated wastewater in agriculture and aquaculture. 'Pits' were mainly working on World Bank LCST research projects, with fieldwork principally in Zimbabwe, 'pipes' were working on condominial sewerage projects in Brazil and disseminating this LCST to a wider global audience, and 'ponds' were waste stabilization ponds, with fieldwork mainly in Brazil, Colombia, Portugal and the United Kingdom, the development of aerated rock filters to polish facultative-pond effluents, and the human-health aspects of treated wastewater use in agriculture and aquaculture, with fieldwork in Brazil and the UK, and the application of quantitative microbial risk analysis. The paper provides a professional perspective and lessons from historical developments and gives recommended future directions based on my career working on low-cost sanitation technologies and treated wastewater use in agriculture and aquaculture. PMID:23490108

  2. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

    PubMed

    Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

    2010-02-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness. PMID:20192469

  3. Effects of self-heating and phase change on the thermal profile of hydrogen isotopes in confined geometries

    SciTech Connect

    Baxamusa, S. Field, J.; Dylla-Spears, R.; Kozioziemski, B.; Suratwala, T.; Sater, J.

    2014-03-28

    Growth of high-quality single-crystal hydrogen in confined geometries relies on the in situ formation of seed crystals. Generation of deuterium-tritium seed crystals in a confined geometry is governed by three effects: self-heating due to tritium decay, external thermal environment, and latent heat of phase change at the boundary between hydrogen liquid and vapor. A detailed computation of the temperature profile for liquid hydrogen inside a hollow shell, as is found in inertial confinement fusion research, shows that seeds are likely to form at the equatorial plane of the shell. Radioactive decay of tritium to helium slowly alters the composition of the hydrogen vapor, resulting in a modified temperature profile that encourages seed formation at the top of the shell. We show that the computed temperature profile is consistent with a variety of experimental observations.

  4. THE USE OF A TREATABILITY STUDY TO INVESTIGATE THE POTENTIAL FOR SELF HEATING & EXOTHERMIC REACTIONS IN DECONTAMINATION MATERIALS AT PFP

    SciTech Connect

    HOPKINS, A.M.

    2005-02-23

    Cerium Nitrate has been proposed for use in the decontamination of plutonium contaminated equipment at the Plutonium Finishing Plant (PFP) located on the Hanford Nuclear Reservation in eastern Washington. A Treatability Study was conducted to determine the validity of this decontamination technology in terms of meeting its performance goals and to understand the risks associated with the use of Cerium Nitrate under the conditions found at the PFP. Fluor Hanford is beginning the decommissioning of the PFP at the Hanford site. Aggressive chemicals are commonly used to remove transuranic contaminants from process equipment to allow disposal as low level waste. Chemicals being considered for decontamination of gloveboxes in PFP include cerium (IV) nitrate in a nitric acid solution, and proprietary commercial solutions that include acids, degreasers, and sequestering agents. Fluor's decontamination procedure involves application of the chemicals, followed by a wipe-down of the contaminated surfaces with rags. This process effectively transfers the decontamination liquids containing the transuranic materials to the rags, which can then be readily packaged for disposal as TRU waste. As part of a treatability study, Fluor Hanford and the Pacific Northwest National Laboratory (PNNL) have evaluated the potential for self-heating and exothermic reactions in the residual decontamination materials and the waste packages. Laboratory analyses and thermal-hydraulic modeling reveal a significant self-heating risk for cerium nitrate solutions when used with cotton rags. Exothermic reactions that release significant heat and off-gas have been discovered for cerium nitrate at higher temperatures. From these studies, limiting conditions have been defined to assure safe operations and waste packaging.

  5. Drainage pits in cohesionless materials: implications for surface of Phobos.

    PubMed

    Horstman, K C; Melosh, H J

    1989-09-10

    Viking orbiter images show grooves and chains of pits crossing the surface of Phobos, many of which converge toward the large crater Stickney or its antipode. Although it has been proposed that the pits and grooves are chains of secondary craters, their morphology and geometric relations suggest that they are the surface traces of fractures in the underlying solid body of Phobos. Several models have been proposed to explain the pits, of which the most plausible are gas venting and drainage of regolith into open fractures. the latter mechanism is best supported by the image data and is the mechanism studied in this investigation. Drainage pits and fissures are modeled experimentally by using two rigid substrate plates placed edge to edge and covered by uniform thicknesses of dry fragmental debris (simulated regolith). Fracture extension is simulated by drawing the plates apart, allowing drainage of regolith into the newly created void. A typical drainage experiment begins with a shallow depression on the surface of the regolith, above the open fissure. Increased drainage causes local drainage pits to form; continued drainage causes the pits to coalesce, forming a cuspate groove. The resulting experimental patterns of pits and grooves have pronounced similarities to those observed on Phobos. Characteristics such as lack of raised rims, linearity of grooves and chains of pits, uniform spacing of pits, and progression from discrete pits to cuspate grooves are the same in the experiments and on Phobos. In contrast, gas-venting pits occur in irregular chains and have raised rims. These experiments thus indicate that the Phobos grooves and pits formed as drainage structures. The pit spacing in an experiment is measured at the time that the maximum number of pits forms, prior to groove development. The average pit spacing is compared to the regolith thickness for each material. Regression line fits indicate that the average spacing of drainage pits in unconsolidated

  6. Flyover Modeling of Planetary Pits - Undergraduate Student Instrument Project

    NASA Astrophysics Data System (ADS)

    Bhasin, N.; Whittaker, W.

    2015-12-01

    On the surface of the moon and Mars there are hundreds of skylights, which are collapsed holes that are believed to lead to underground caves. This research uses Vision, Inertial, and LIDAR sensors to build a high resolution model of a skylight as a landing vehicle flies overhead. We design and fabricate a pit modeling instrument to accomplish this task, implement software, and demonstrate sensing and modeling capability on a suborbital reusable launch vehicle flying over a simulated pit. Future missions on other planets and moons will explore pits and caves, led by the technology developed by this research. Sensor software utilizes modern graph-based optimization techniques to build 3D models using camera, LIDAR, and inertial data. The modeling performance was validated with a test flyover of a planetary skylight analog structure on the Masten Xombie sRLV. The trajectory profile closely follows that of autonomous planetary powered descent, including translational and rotational dynamics as well as shock and vibration. A hexagonal structure made of shipping containers provides a terrain feature that serves as an appropriate analog for the rim and upper walls of a cylindrical planetary skylight. The skylight analog floor, walls, and rim are modeled in elevation with a 96% coverage rate at 0.25m2 resolution. The inner skylight walls have 5.9cm2 color image resolution and the rims are 6.7cm2 with measurement precision superior to 1m. The multidisciplinary student team included students of all experience levels, with backgrounds in robotics, physics, computer science, systems, mechanical and electrical engineering. The team was commited to authentic scientific experimentation, and defined specific instrument requirements and measurable experiment objectives to verify successful completion.This work was made possible by the NASA Undergraduate Student Instrument Project Educational Flight Opportunity 2013 program. Additional support was provided by the sponsorship of an

  7. Distribution, morphology, and origins of Martian pit crater chains

    NASA Astrophysics Data System (ADS)

    Wyrick, Danielle; Ferrill, David A.; Morris, Alan P.; Colton, Shannon L.; Sims, Darrell W.

    2004-06-01

    Pit craters are circular to elliptical depressions found in alignments (chains), which in many cases coalesce into linear troughs. They are common on the surface of Mars and similar to features observed on Earth and other terrestrial bodies. Pit craters lack an elevated rim, ejecta deposits, or lava flows that are associated with impact craters or calderas. It is generally agreed that the pits are formed by collapse into a subsurface cavity or explosive eruption. Hypotheses regarding the formation of pit crater chains require development of a substantial subsurface void to accommodate collapse of the overlying material. Suggested mechanisms of formation include: collapsed lava tubes, dike swarms, collapsed magma chamber, substrate dissolution (analogous to terrestrial karst), fissuring beneath loose material, and dilational faulting. The research described here is intended to constrain current interpretations of pit crater chain formation by analyzing their distribution and morphology. The western hemisphere of Mars was systematically mapped using Mars Orbiter Camera (MOC) images to generate ArcView™ Geographic Information System (GIS) coverages. All visible pit crater chains were mapped, including their orientations and associations with other structures. We found that pit chains commonly occur in areas that show regional extension or local fissuring. There is a strong correlation between pit chains and fault-bounded grabens. Frequently, there are transitions along strike from (1) visible faulting to (2) faults and pits to (3) pits alone. We performed a detailed quantitative analysis of pit crater morphology using MOC narrow angle images, Thermal Emission Imaging System (THEMIS) visual images, and Mars Orbiter Laser Altimeter (MOLA) data. This allowed us to determine a pattern of pit chain evolution and calculate pit depth, slope, and volume. Volumes of approximately 150 pits from five areas were calculated to determine volume size distribution and regional

  8. Experimental investigation of road snow-melting based on CNFP self-heating concrete

    NASA Astrophysics Data System (ADS)

    Zhang, Qiangqiang; Li, Hui

    2011-04-01

    In this study, the road snow-melting system consisted of CNFP thermal source, AlN/Epoxy-based insulated-encapsulated layer and MWCNT/cement-based thermal conductive layer, was fabricated. The carbon nano-fiber paper (CNFP) taken excellent thermal and electrical properties was integrated into snow-melting system as the high-efficient thermal source. The remarkable electro-thermal and resistive properties of CNFP with the thickness of 0.38mm were investigated, and verified much higher efficiency electro-thermal property than other papery materials. The linearly temperature-dependent effect of CNFP resistivity was founded in certain temperature scope and met the line model as a function of temperature. Carbon nanotubes (CNT) attracted many filed scholars' focus based on its unique thermal conduction as a strong thermal-transferring candidate since it was founded. A new approach, named electric repulsion/high-frequency oscillatory dispersion, was proposed to fabricate the MWCNT/cement-based composites. The sample, filled with 3% MWCNT by the amount of cement, presents the significant improvement of thermal conductive property in contrast with other fillers and dispersing methods, which was integrated into snow-melting system with other parts as the thermal conductive layer material. The AlN/Epoxy-based composite, filled with 20% micron-AlN by the weight of mixture as the best candidate of insulated-capsulation material, would be used to guarantee the insulation. Due to the snow-melting field test, the snow-melting characteristics of integrated snow-melting system, dependent on the ambient temperature, wind speed, heat flux density and snow thickness, were investigated. The results not only verified the high-efficient, stable, feasible and economic properties, but also provided the valuable parameters for further snow-melting or ice-deicing investigation.

  9. Pitted terrains on Vesta: Thermophysical analysis

    NASA Astrophysics Data System (ADS)

    Capria, M.; Tosi, F.; De Sanctis, M.; Turrini, D.; Ammannito, E.; Capaccioni, F.; Fonte, S.; Frigeri, A.; Longobardo, A.; Palomba, E.; Zambon, F.; Schroeder, S.; Denevi, B.; Williams, D.; Scully, J.; Russell, C.; Raymond, C.

    2014-07-01

    Launched in 2007, the Dawn spacecraft, after one year spent orbiting Vesta, is now on its way to Ceres. In the science payload, the Visible and Infrared mapping spectrometer (VIR) is devoted to the study of the mineralogical composition and thermophysical properties of Vesta's surface [1]. Disk-resolved surface temperatures of Vesta have been determined from the infrared spectra measured by VIR [2]. The observed temperatures, together with a thermophysical model, have been used to constrain the thermal properties of a large part of the surface of the asteroid [3]. The average thermal inertia of the surface is quite low, consistent with a widespread presence of a dust layer. While the global thermal inertia is low, the characterization of its surface in terms of regions showing peculiar thermophysical properties gives us the possibility to identify specific areas with different thermal and structural characteristics. These variations can be linked to strong albedo variations that have been observed, or to other physical and structural characteristics of the first few centimeters of the soil. The highest values of thermal inertia have been determined on areas coinciding with locations where pitted terrains have been found [4]. Pitted terrains, first identified on Mars, have been found in association with 4 craters on Vesta: Marcia, Cornelia, Licinia, and Numisia. The Marcia area is characterized by high hydrogen and OH content [5]. By analogy with Mars, the formation of these terrains is thought to be due to the rapid release of volatiles, triggered by heating from an impact event. A question arises on the origin of volatiles: hydrated minerals, or ground, buried ice? In order to discuss the second hypothesis, we have to assume that a comet impact delivers ice that gets buried under a layer of regolith. Successively, another impact on the same area would give origin to the pitted terrain. The buried ice has obviously to survive for the time between the two impacts

  10. Coordinate Measuring Machine Pit Artifact Inspection Procedure

    SciTech Connect

    Montano, Joshua D.

    2012-07-31

    The goal of this document is to outline a procedure for dimensional measurement of Los Alamos National Laboratory's CMM Pit Artifact. This procedure will be used by the Manufacturing Practice's Inspection Technology Subgroup of the Interagency Manufacturing Operations Group and Joint Operations Weapon Operations Group (IMOG/JOWOG 39) round robin participants. The intent is to assess the state of industry within the Nuclear Weapons Complex for measurements made on this type of part and find which current measurement strategies and techniques produce the best results.

  11. The Pit and the Safety Pendulum

    SciTech Connect

    Nitschke, Robert Leon; Ramos, Amadeo Gabriel

    2000-11-01

    The hypothesis of this paper is that the safety analysis pendulum has swung considerably in the direction of increasingly complex and lengthy safety evaluations and intense reviews during the past 30 years. The test of this hypothesis will be a review of the safety analysis conducted for various activities associated with the retrieval of transuranic radioactive waste from burial pits at a National Laboratory site over a span of 30 years. The examination will focus on the safety aspects and the safety analysis that was conducted for the projects. At the conclusion of this examination, the paper will identify five reasons why the changes have taken place.

  12. Pitting of Space Shuttle's Inconel Honeycomb Conical Seal Panel

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank; Gentz, Steven J.; Miller, James B.

    2006-01-01

    This paper describes the approach, findings, conclusions and recommendations associated with the investigation of the conical seal pitting. It documents the cause and contributing factors of the pitting, the means used to isolate each contributor, and the supporting evidence for the primary cause of the pitting. Finally, the selection, development and verification of the repair procedure used to restore the conical seal panel is described with supporting process and metallurgical rationale for selection.

  13. 18. DETAIL, INSPECTION PIT Delaware, Lackawanna & Western Railroad ...

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

    18. DETAIL, INSPECTION PIT - Delaware, Lackawanna & Western Railroad Freight & Rail Yard, Multiple Unit Light Inspection Shed, New Jersey Transit Hoboken Terminal Rail Yard, Hoboken, Hudson County, NJ

  14. Electrochemical Studies of Nitrate-Induced Pitting in Carbon Steel

    SciTech Connect

    Zapp, P.E.

    1998-12-07

    The phenomenon of pitting in carbon steel exposed to alkaline solutions of nitrate and chloride was studied with the cyclic potentiodynamic polarization technique. Open-circuit and pitting potentials were measured on specimens of ASTM A537 carbon steel in pH 9.73 salt solutions at 40 degrees Celsius, with and without the inhibiting nitrite ion present. Nitrate is not so aggressive a pitting agent as is chloride. Both nitrate and chloride did induce passive breakdown and pitting in nitrite-free solutions, but the carbon steel retained passivity in solutions with 0.11-M nitrite even at a nitrate concentration of 2.2 M.

  15. Lessons Learned from Pit Viper System Deployment

    SciTech Connect

    Catalan, Michael A.; Alzheimer, James M.; Valdez, Patrick LJ; Bailey, Sharon A.; Baker, Carl P.

    2002-04-11

    Tele-operated and robotic systems operated in unstructured field environments pose unique challenges for tool design. Since field tasks are not always well defined and the robot work area usually cannot be designed for ease of operation, the tools must be versatile. It's important to carefully consider the orientation of the grip the robot takes on the tool, as it's not easily changed in the field. The stiffness of the robot and the possibility of robot positioning errors encourages the use of non-contact or minimal-contact tooling. While normal hand tools can usually be modified for use by the robot, this is not always the most effective approach. It's desirable to have tooling that is relatively independent of the robot; in this case, the robot places the tool near the desired work location and the tool performs its task relatively independently. Here we consider the adaptation of a number of tools for cleanup of a radioactively contaminated piping junction and valve pit. The tasks to be considered are debris removal (small nuts and bolts and pipe up to 100 mm in diameter), size reduction, surface cleaning, and support of past practice crane-based methods for working in the pits.

  16. Introduction to Pits and Weapons Systems (U)

    SciTech Connect

    Kautz, D.

    2012-07-02

    A Nuclear Explosive Package includes the Primary, Secondary, Radiation Case and related components. This is the part of the weapon that produces nuclear yield and it converts mechanical energy into nuclear energy. The pit is composed of materials that allow mechanical energy to be converted to electromagnetic energy. Fabrication processes used are typical of any metal fabrication facility: casting, forming, machining and welding. Some of the materials used in pits include: Plutonium, Uranium, Stainless Steel, Beryllium, Titanium, and Aluminum. Gloveboxes are used for three reasons: (1) Protect workers and public from easily transported, finely divided plutonium oxides - (a) Plutonium is very reactive and produces very fine particulate oxides, (b) While not the 'Most dangerous material in the world' of Manhattan Project lore, plutonium is hazardous to health of workers if not properly controlled; (2) Protect plutonium from reactive materials - (a) Plutonium is extremely reactive at ambient conditions with several components found in air: oxygen, water, hydrogen, (b) As with most reactive metals, reactions with these materials may be violent and difficult to control, (c) As with most fabricated metal products, corrosion may significantly affect the mechanical, chemical, and physical properties of the product; and (3) Provide shielding from radioactive decay products: {alpha}, {gamma}, and {eta} are commonly associated with plutonium decay, as well as highly radioactive materials such as {sup 241}Am and {sup 238}Pu.

  17. Real-time electronic monitoring of a pitted and leaking gas gathering pipeline

    SciTech Connect

    Asperger, R.G.; Hewitt, P.G.

    1986-08-01

    Hydrogen patch, flush electrical resistance, and flush linear polarization proves wre used with flush coupons to monitor corrosion rates in a pitted and leaking sour gas gathering line. Four inhibitors were evaluated in stopping the leaks. Inhibitor residuals and the amount and ratio of water and condensate in the lines were measured at five locations along the line. The best inhibitor reduced reduced the pit-leak frequency by over a factor of 10. Inhibitor usage rate was optimized using the hydrogen patch current as a measure of the instantaneous corrosion rate. Improper pigging was identified as a cause of corrosion transients. This problem is discussed in relation to the pigging of pipelines in stratified flow where moving fluids are the carriers for continuously injected corrosion inhibitors.

  18. Numerical modelling of the groundwater inflow to an advancing open pit mine: Kolahdarvazeh pit, Central Iran.

    PubMed

    Bahrami, Saeed; Doulati Ardejani, Faramarz; Aslani, Soheyla; Baafi, Ernest

    2014-12-01

    The groundwater inflow into a mine during its life and after ceasing operations is one of the most important concerns of the mining industry. This paper presents a hydrogeological assessment of the Irankuh Zn-Pb mine at 20 km south of Esfahan and 1 km northeast of Abnil in west-Central Iran. During mine excavation, the upper impervious bed of a confined aquifer was broken and water at high-pressure flowed into an open pit mine associated with the Kolahdarvazeh deposit. The inflow rates were 6.7 and 1.4 m(3)/s at the maximum and minimum quantities, respectively. Permeability, storage coefficient, thickness and initial head of the fully saturated confined aquifer were 3.5 × 10(-4) m/s, 0.2, 30 m and 60 m, respectively. The hydraulic heads as a function of time were monitored at four observation wells in the vicinity of the pit over 19 weeks and at an observation well near a test well over 21 h. In addition, by measuring the rate of pumping out from the pit sump, at a constant head (usually equal to height of the pit floor), the real inflow rates to the pit were monitored. The main innovations of this work were to make comparison between numerical modelling using a finite element software called SEEP/W and actual data related to inflow and extend the applicability of the numerical model. This model was further used to estimate the hydraulic heads at the observation wells around the pit over 19 weeks during mining operations. Data from a pump-out test and observation wells were used for model calibration and verification. In order to evaluate the model efficiency, the modelling results of inflow quantity and hydraulic heads were compared to those from analytical solutions, as well as the field data. The mean percent error in relation to field data for the inflow quantity was 0.108. It varied between 1.16 and 1.46 for hydraulic head predictions, which are much lower values than the mean percent errors resulted from the analytical solutions (from 1.8 to 5

  19. Secrets of the Noachian Highlands: Pit Craters

    NASA Technical Reports Server (NTRS)

    2001-01-01

    [figure removed for brevity, see original site] A) Context Image [figure removed for brevity, see original site] B) Gullies in M12-00595 [figure removed for brevity, see original site] C) Layers and gullies in M09-00539, M15-00964

    Among the most exciting places that the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) has photographed during its three and a half years in orbit has been this crater in central Noachis Terra. Located at 47oS, 355oW, the crater appears to have been almost completely filled, and subsequently eroded in localized pits, by unknown processes. In this one place we see elements of the two most important results of the MOC investigation--the discovery of young gullies formed by fluid erosion and the occurrence of thick sequences of layered rock attesting to a martian past of substantial geologic activity.

    Picture A shows the location of the other two figures, which are sections of three of about a dozen images acquired of this crater. Picture B (M12-00595) shows examples of gullies on the pit walls. Their contributary pattern (including the angles at which they join) argues for fluid behavior during their creation; the dark floors suggest that they have been active recently (or else they, like the slopes around them and most of Mars, would be lighter-toned owing to the accumulation of dust). These gullies are formed well down on the pit wall, where a distinctive, boulder-rich layer is found. Figure C, a mosaic of two high resolution images (M09-00539 and M15-00964), shows an area somewhat higher in the sequence of layered material that fills the crater. This sequence clearly alternates between layers that either contain or erode to form boulders and layers that do not have boulders. Note in particular the overhanging layers near the top center--such overhangs are evidence of the strength of the material. Here, too, gullies appear to start at specific layers; these, however, may not be as young as those seen in (B), as they appear to

  20. Power delivery and self-heating in nanoscale near field transducer for heat-assisted magnetic recording.

    PubMed

    Zhou, Nan; Traverso, Luis M; Xu, Xianfan

    2015-03-27

    To keep increasing the storage density in next-generation hard disk drives, heat-assisted magnetic recording is being developed where a nanoscale near field transducer (NFT) locally and temporally heats a sub-diffraction-limited region in the recording medium to reduce the magnetic coercivity. This allows the use of very small grain in the medium while still maintaining data thermal stability. Plasmonic nanostructures made of apertures or antennas are good candidates for NFTs because of their capability of subwavelength light manipulation in optical frequencies. The NFT must simultaneously deliver enough power to the recording medium with as small as possible incident laser power to reduce self-heating in the NFT, which could cause thermal expansion and materials failure that lead to degradation of the overall hard drive performance. In this work, we study the effect of optical properties on the power delivery efficiency of nanoscale bowtie aperture antennas, with the presence of a recording media stack. Heat dissipation and temperature rise in the NFT are also computed to investigate their dependence on materials' properties. The possibility of using alternative plasmonic materials for delivering higher power and/or reducing heating in NFTs is discussed. PMID:25759907

  1. Plasmodesmata and pit development in secondary xylem elements.

    PubMed

    Barnett, J R

    1982-08-01

    Developing pit membranes of secondary xylem elements in Drimys winteri, Fagus sylvatica, Quercus robur, Sorbus aucuparia, Tilia vulgaris and Trochodendron aralioides have been examined by transmission electron microscopy. Absence of plasmodesmata from the membranes of vessel elements and tracheids indicates that their pits develop independently of these structures. On the other hand, plasmodesmata are abundant in pit membranes between fibres, parenchyma cells, and combinations of these cell types in Fagus, Quercus and Tilia. In each case the plasmodesmata pass right through the developing pit membrane. In the case of Sorbus fibres, however, plasmodesmata were absent from the majority of pit membrane profiles seen in sections. Occasionally they were observed in large numbers associated with a swollen region on one side of the pit membrane between fibres and between fibres and parenchyma, radiating from a small area of the middle lamella. In the case of fibre to parenchyma pitting, this swelling was always found on the fibre side of the membrane, while on the other side a small number of plasmodesmata were present completing communication with the parenchyma cytoplasm. These observations are discussed with regard to the role of plasmodesmata in pit formation, and in the differentiation of the various cell types in secondary xylem. The significance their distribution may have for our understanding of xylem evolution is also discussed. PMID:24271775

  2. 103. ARAIII. Looking down into GCRE reactor pit as it ...

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

    103. ARA-III. Looking down into GCRE reactor pit as it was being modified for further ML-1 testing. Shows bellows assembly, men working in pit, spiral staircase. May 20, 1965. Ineel photo no. 65-2762. Photographer: Farmer. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

  3. 7 CFR 52.807 - Freedom from pits.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... United States Standards for Grades of Frozen Red Tart Pitted Cherries Factors of Quality § 52.807 Freedom... substantially free from any adhering sirup, sugar, or other packing medium. (c) (A) Classification. Frozen red... for this classification specified in Table I. (d) (B) Classification. Frozen red tart pitted...

  4. 7 CFR 52.807 - Freedom from pits.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... United States Standards for Grades of Frozen Red Tart Pitted Cherries Factors of Quality § 52.807 Freedom... substantially free from any adhering sirup, sugar, or other packing medium. (c) (A) Classification. Frozen red... for this classification specified in Table I. (d) (B) Classification. Frozen red tart pitted...

  5. 7 CFR 52.807 - Freedom from pits.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... United States Standards for Grades of Frozen Red Tart Pitted Cherries Factors of Quality § 52.807 Freedom... substantially free from any adhering sirup, sugar, or other packing medium. (c) (A) Classification. Frozen red... for this classification specified in Table I. (d) (B) Classification. Frozen red tart pitted...

  6. 7 CFR 52.779 - Freedom from pits.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Freedom from pits. 52.779 Section 52.779 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Cherries 1 Factors of Quality § 52.779 Freedom from pits. (a) General. The factor of freedom from...

  7. 7 CFR 52.779 - Freedom from pits.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Freedom from pits. 52.779 Section 52.779 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Cherries 1 Factors of Quality § 52.779 Freedom from pits. (a) General. The factor of freedom from...

  8. Pit- and trench-forming osteoclasts: a distinction that matters

    PubMed Central

    Merrild, Ditte MH; Pirapaharan, Dinisha C; Andreasen, Christina M; Kjærsgaard-Andersen, Per; Møller, Anaïs MJ; Ding, Ming; Delaissé, Jean-Marie; Søe, Kent

    2015-01-01

    Osteoclasts (OCs) seeded on bone slices either drill round pits or dig long trenches. Whereas pits correspond to intermittent resorption, trenches correspond to continuous and faster resorption and require a distinct assembly of the resorption apparatus. It is unknown whether the distinction between pits and trenches has any biological relevance. Using OCs prepared from different blood donors, we found that female OCs achieved increased resorption mainly through pit formation, whereas male OCs did so through trench formation. Trench formation went along with high collagenolytic activity and high cathepsin K (CatK) expression, thereby allowing deeper demineralization. A specific CatK inhibitor abrogated the generation of trenches, while still allowing the generation of pits. OCs obtained from bone marrow were more prone to generate trenches than those obtained from blood. Scanning electron microscopy of bone surfaces eroded in vivo showed trenches and pits of similar size as those made by OCs in culture. We conclude that the distinction between trench- and pit-forming OCs is relevant to the differences among OCs from different skeletal sites, different individuals, including gender, and results from differences in collagenolytic power. This indicates a biological relevance and highlights the importance of discriminating between pits and trenches when assessing resorption. PMID:26664853

  9. 241-AY-102 Leak Detection Pit Drain Line Inspection Report

    SciTech Connect

    Boomer, Kayle D.; Engeman, Jason K.; Gunter, Jason R.; Joslyn, Cameron C.; Vazquez, Brandon J.; Venetz, Theodore J.; Garfield, John S.

    2014-01-20

    This document provides a description of the design components, operational approach, and results from the Tank AY-102 leak detection pit drain piping visual inspection. To perform this inspection a custom robotic crawler with a deployment device was designed, built, and operated by IHI Southwest Technologies, Inc. for WRPS to inspect the 6-inch leak detection pit drain line.

  10. 14. TURNTABLE PIT: Photocopy of December 1940 photograph of the ...

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

    14. TURNTABLE PIT: Photocopy of December 1940 photograph of the turntable pit at Bay and Taylor Streets. View is to the north. Market Street Railway was in the process of moving the turntable from its original location, where the car is being turned in the background, to its present site. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA

  11. Modelling the mechanical behaviour of pit membranes in bordered pits with respect to cavitation resistance in angiosperms

    PubMed Central

    Tixier, Aude; Herbette, Stephane; Jansen, Steven; Capron, Marie; Tordjeman, Philippe; Cochard, Hervé; Badel, Eric

    2014-01-01

    Background and Aims Various correlations have been identified between anatomical features of bordered pits in angiosperm xylem and vulnerability to cavitation, suggesting that the mechanical behaviour of the pits may play a role. Theoretical modelling of the membrane behaviour has been undertaken, but it requires input of parameters at the nanoscale level. However, to date, no experimental data have indicated clearly that pit membranes experience strain at high levels during cavitation events. Methods Transmission electron microscopy (TEM) was used in order to quantify the pit micromorphology of four tree species that show contrasting differences in vulnerability to cavitation, namely Sorbus aria, Carpinus betulus, Fagus sylvatica and Populus tremula. This allowed anatomical characters to be included in a mechanical model that was based on the Kirchhoff–Love thin plate theory. A mechanistic model was developed that included the geometric features of the pits that could be measured, with the purpose of evaluating the pit membrane strain that results from a pressure difference being applied across the membrane. This approach allowed an assessment to be made of the impact of the geometry of a pit on its mechanical behaviour, and provided an estimate of the impact on air-seeding resistance. Key Results The TEM observations showed evidence of residual strains on the pit membranes, thus demonstrating that this membrane may experience a large degree of strain during cavitation. The mechanical modelling revealed the interspecific variability of the strains experienced by the pit membrane, which varied according to the pit geometry and the pressure experienced. The modelling output combined with the TEM observations suggests that cavitation occurs after the pit membrane has been deflected against the pit border. Interspecific variability of the strains experienced was correlated with vulnerability to cavitation. Assuming that air-seeding occurs at a given pit membrane

  12. Millennium Open Pit Mine, Alberta, Canada

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Near Fort McMurray, Alberta, Canada, on the east bank of the Athabasca River, are found the Steepbank and Millennium mines. These open pit mines produce oil sands that are processed to recover bitumen, and then upgrade it to refinery-ready raw crude oil, and diesel fuel.

    The ASTER images were acquired September 22, 2000 and July 31, 2007, cover an area of 22.5 x 25.5 km, and are located near 57 degrees north latitude, 111.5 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  13. Crevice and pitting corrosion behavior of stainless steels in seawater

    SciTech Connect

    Zaragoza-Ayala, A.E.; Orozco-Cruz, R.

    1999-11-01

    Pitting and crevice corrosion tests in natural seawater were performed on a series of stainless steels (i.e., S31603, N08904, S32304, S31803, S32520, N08925 and S31266) in order to determine their resistance to these types of localized corrosion. Open circuit potential (OCP) measurements for these alloys show for short exposure times an ennoblement in the OCP. After a certain time, occasional fall and rise in the OCP values was observed, which can be related to nucleation and repassivation of pits and/or crevices on the metal surface. Analysis of the electrochemical behavior and microscopic observations shows that only S31603 and S32304 alloys were susceptible to crevice and pitting corrosion, whereas the remaining alloys exhibited good resistance. Pitting potentials determined by the potentiodynamic technique also show S3 1603 and S32304 are susceptible to pitting corrosion under the experimental conditions used in this work.

  14. Mapping sand and gravel pits in the Patuxent River watershed

    NASA Technical Reports Server (NTRS)

    Schmidt, T. J.; Witt, R. G.

    1981-01-01

    LANDSAT data from July 1973 and June 1978 for the Patuxent River Watershed of Maryland were processed in an effort to devise an economical method of monitoring the reclamation of sand and gravel pits. ASTEP-II and IDIMS software were utilized to derive signatures for sand and gravel pits and other land use/land cover types. Both unsupervised and supervised classifications of the two data sets were produced. Resultant statistics and color output products were compared in order to determine the extent of reclamation and expansion of sand and gravel pits over the five-year time span and to check the locations of more recent sand and gravel pits. Preliminary results indicate that, for a selected northern sub-acre, signatures derived for sand and gravel pits were nearly 90 percent accurate.

  15. Influence of animal waste disposal pits on groundwater quality

    NASA Astrophysics Data System (ADS)

    Lee, Seongwon; Hosaka, Akiko; Tase, Norio

    Since the implementation of the Law on Promoting Proper Management and Use of Livestock Excreta in 1999, the number of the farmers that do not meet the management criteria is on the decline. However, there is a possibility that many of the animal waste disposal pits that have been either abandoned or refilled according to the law have been the potential contamination source. In this study, we discussed the impacts of the abandoned disposal pits to groundwater quality. The results showed that high concentrations of nitrate (above 100mg/L) were observed in the downstream of the disposal pits. It suggests that the abandoned animal waste disposal pits have been the potential pollution source even after the period of 15 years since the termination of use. Implementation of immediate countermeasure is necessary because the animal waste disposal pits are the long-term-sources of high levels of nitrate.

  16. Microbial contents of soil from fire pits

    NASA Astrophysics Data System (ADS)

    Moon, K.; Esparza, V.; de Sandre, J.; Cheney, S.; Anderson, A.; White, M. A.

    2006-12-01

    Forest fires generate polycylic aromatic hydrocarbons (PAHs) that can lead to carcinogenic compounds, which are potential health risks. PAHs can be degraded to water and carbon dioxide by certain soil microbes. Thus, during participation in a NASA-funded summer research experience at Utah State University, our high school student team sampled soils from a month-old fire pit in which plant materials had been burnt. We detected in soil samples, from surface, 10 and 20 cm depths, microbes that would grow on a defined minimal medium source. Other microbes were cultured from the roots of plants that had established at the fire pit. A diversity of microbes was present in all samples based on visible differences in cell shape and color. It was surprising that the surface ash, although exposed to sunlight over the month interval, had culturable colonies. Many of these culturable bacteria were pigmented perhaps as a protection against UV radiation from the sun. We searched for genes in the microbes that encoded enzymes called dioxygenases that in other bacteria are involved in degradation of PAHs. This test involved using polymerase chain reactions to detect the genes. PCR products were found in two of the fifteen isolates tested although their sizes differed from the control gene product from a PAH-degrading mycobacterium isolate. These results suggest that the soils did contain microbes with the possible potential to alter the PAH compounds generated from vegetation fires. Our findings serve as a starting point for future studies looking at recovery and remediation of fired acreages.

  17. Lunar Pit Craters Presumed to be the Entrances of Lava Caves by Analogy to the Earth Lava Tube Pits

    NASA Astrophysics Data System (ADS)

    Hong, Ik-Seon; Yi, Yu; Kim, Eojin

    2014-06-01

    Lava caves could be useful as outposts for the human exploration of the Moon. Lava caves or lava tubes are formed when the external surface of the lava flows cools more quickly to make a hardened crust over subsurface lava flows. The lava flow eventually ceases and drains out of the tube, leaving an empty space. The frail part of the ceiling of lava tube could collapse to expose the entrance to the lava tubes which is called a pit crater. Several pit craters with the diameter of around 100 meters have been found by analyzing the data of SELENE and LRO lunar missions. It is hard to use these pit craters for outposts since these are too large in scale. In this study, small scale pit craters which are fit for outposts have been investigated using the NAC image data of LROC. Several topographic patterns which are believed to be lunar caves have been found and the similar pit craters of the Earth were compared and analyzed to identify caves. For this analysis, the image data of satellites and aerial photographs are collected and classified to construct a database. Several pit craters analogous to lunar pit craters were derived and a morphological pit crater model was generated using the 3D printer based on this database.

  18. Method for Identifying Lava Tubes Among Pit Craters Using Brightness Profile Across Pits on the Moon or Mars

    NASA Astrophysics Data System (ADS)

    Jung, Jongil; Hong, Ik-Seon; Cho, Eunjin; Yi, Yu

    2016-03-01

    Caves can serve as major outposts for future human exploration of the Moon and Mars. In addition, caves can protect people and electronic equipment from external hazards such as cosmic ray radiation and meteorites impacts and serve as a shelter. Numerous pit craters have been discovered on the Moon and Mars and are potential entrances to caves; the principal topographic features of pit craters are their visible internal floors and pits with vertical walls. We have devised two topographical models for investigating the relationship between the topographical characteristics and the inner void of pit craters. One of our models is a concave floor void model and the other is a convex floor tube model. For each model, optical photographs have been obtained under conditions similar to those in which optical photographs have been acquired for craters on the Moon and Mars. Brightness profiles were analyzed for determining the profile patterns of the void pit craters. The profile patterns were compared to the brightness profiles of Martian pit craters, because no good-quality images of lunar pit craters were available. In future studies, the model profile patterns will be compared to those of lunar pit craters, and the proposed method will likely become useful for finding lunar caves and consequently for planning lunar bases for manned lunar expeditions.

  19. Suppression of self-heating effect in AlGaN/GaN high electron mobility transistors by substrate-transfer technology using h-BN

    SciTech Connect

    Hiroki, Masanobu Kumakura, Kazuhide; Kobayashi, Yasuyuki; Akasaka, Tetsuya; Makimoto, Toshiki; Yamamoto, Hideki

    2014-11-10

    We fabricated AlGaN/GaN high electron mobility transistors (HEMTs) on h-BN/sapphire substrates and transferred them from the host substrates to copper plates using h-BN as a release layer. In current–voltage characteristics, the saturation drain current decreased by about 30% under a high-bias condition before release by self-heating effect. In contrast, after transfer, the current decrement was as small as 8% owing to improved heat dissipation: the device temperature increased to 50 °C in the as-prepared HEMT, but only by several degrees in the transferred HEMT. An effective way to improve AlGaN/GaN HEMT performance by a suppression of self-heating effect has been demonstrated.

  20. 37. ELECTRICAL PLAN AND DETAILS. SHOWS PLANNED LOCATION OF PORTABLE ...

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

    37. ELECTRICAL PLAN AND DETAILS. SHOWS PLANNED LOCATION OF PORTABLE GENERATOR. FUNCTION OF FOUR-FOOT SQUARE PIT IS SHOWN AS 'D.C. POWER SUPPLY PIT.' F.C. TORKELSON DRAWING NUMBER 842-ARVFS-701-E-1. INEL INDEX CODE NUMBER: 075 0701 10 851 151973. - Idaho National Engineering Laboratory, Advanced Reentry Vehicle Fusing System, Scoville, Butte County, ID

  1. Self-heating probe instrument and method for measuring high temperature melting volume change rate of material

    NASA Astrophysics Data System (ADS)

    Wang, Junwei; Wang, Zhiping; Lu, Yang; Cheng, Bo

    2013-03-01

    The castings defects are affected by the melting volume change rate of material. The change rate has an important effect on running safety of the high temperature thermal storage chamber, too. But the characteristics of existing measuring installations are complex structure, troublesome operation and low precision. In order to measure the melting volume change rate of material accurately and conveniently, a self-designed measuring instrument, self-heating probe instrument, and measuring method are described. Temperature in heating cavity is controlled by PID temperature controller; melting volume change rate υ and molten density are calculated based on the melt volume which is measured by the instrument. Positive and negative υ represent expansion and shrinkage of the sample volume after melting, respectively. Taking eutectic LiF+CaF2 for example, its melting volume change rate and melting density at 1 123 K are -20.6% and 2 651 kg·m-3 measured by this instrument, which is only 0.71% smaller than literature value. Density and melting volume change rate of industry pure aluminum at 973 K and analysis pure NaCl at 1 123 K are detected by the instrument too. The measure results are agreed with report values. Measuring error sources are analyzed and several improving measures are proposed. In theory, the measuring errors of the change rate and molten density which are measured by the self-designed instrument is nearly 1/20-1/50 of that measured by the refitted mandril thermal expansion instrument. The self-designed instrument and method have the advantages of simple structure, being easy to operate, extensive applicability for material, relatively high accuracy, and most importantly, temperature and sample vapor pressure have little effect on the measurement accuracy. The presented instrument and method solve the problems of complicated structure and procedures, and large measuring errors for the samples with high vapor pressure by existing installations.

  2. Pit assisted oxygen chemisorption on GaN surfaces.

    PubMed

    Mishra, Monu; Krishna T C, Shibin; Aggarwal, Neha; Kaur, Mandeep; Singh, Sandeep; Gupta, Govind

    2015-06-21

    A comprehensive analysis of oxygen chemisorption on epitaxial gallium nitride (GaN) films grown at different substrate temperatures via RF-molecular beam epitaxy was carried out. Photoemission (XPS and UPS) measurements were performed to investigate the nature of the surface oxide and corresponding changes in the electronic structure. It was observed that the growth of GaN films at lower temperatures leads to a lower amount of surface oxide and vice versa was observed for a higher temperature growth. The XPS core level (CL) and valence band maximum (VBM) positions shifted towards higher binding energies (BE) with oxide coverage and revealed a downward band bending. XPS valence band spectra were de-convoluted to understand the nature of the hybridization states. UPS analysis divulged higher values of electronic affinity and ionization energy for GaN films grown at a higher substrate temperature. The surface morphology and pit structure were probed via microscopic measurements (FESEM and AFM). FESEM and AFM analysis revealed that the film surface was covered with hexagonal pits, which played a significant role in oxygen chemisorption. The favourable energetics of the pits offered an ideal site for oxygen adsorption. Pit density and pit depth were observed to be important parameters that governed the surface oxide coverage. The contribution of surface oxide was increased with an increase in average pit density as well as pit depth. PMID:25991084

  3. Relationship between the Foveal Avascular Zone and Foveal Pit Morphology

    PubMed Central

    Dubis, Adam M.; Hansen, Benjamin R.; Cooper, Robert F.; Beringer, Joseph; Dubra, Alfredo; Carroll, Joseph

    2012-01-01

    Purpose. To assess the relationship between foveal pit morphology and size of the foveal avascular zone (FAZ). Methods. Forty-two subjects were recruited. Volumetric images of the macula were obtained using spectral domain optical coherence tomography. Images of the FAZ were obtained using either a modified fundus camera or an adaptive optics scanning light ophthalmoscope. Foveal pit metrics (depth, diameter, slope, volume, and area) were automatically extracted from retinal thickness data, whereas the FAZ was manually segmented by two observers to extract estimates of FAZ diameter and area. Results. Consistent with previous reports, the authors observed significant variation in foveal pit morphology. The average foveal pit volume was 0.081 mm3 (range, 0.022 to 0.190 mm3). The size of the FAZ was also highly variable between persons, with FAZ area ranging from 0.05 to 1.05 mm2 and FAZ diameter ranging from 0.20 to 1.08 mm. FAZ area was significantly correlated with foveal pit area, depth, and volume; deeper and broader foveal pits were associated with larger FAZs. Conclusions. Although these results are consistent with predictions from existing models of foveal development, more work is needed to confirm the developmental link between the size of the FAZ and the degree of foveal pit excavation. In addition, more work is needed to understand the relationship between these and other anatomic features of the human foveal region, including peak cone density, rod-free zone diameter, and Henle fiber layer. PMID:22323466

  4. Formation and arrangement of pits by a corrosive gas

    NASA Astrophysics Data System (ADS)

    Burridge, James; Inkpen, Robert

    2015-02-01

    When corroding or otherwise aggressive particles are incident on a surface, pits can form. For example, under certain circumstances rock surfaces that are exposed to salts can form regular tessellating patterns of pits known as "tafoni." We introduce a simple lattice model in which a gas of corrosive particles, described by a discrete, biased diffusion equation, drifts onto a surface. Each gas particle has a fixed probability of being absorbed and causing damage at each contact. The surface is represented by a lattice of strength numbers which reduce after each absorbtion event, with sites being removed when their strength becomes negative. Regular formations of pits arise spontaneously, with each pit having a characteristic trapezoidal geometry determined by the particle bias, absorbtion probability, and surface strength. The formation of this geometry may be understood in terms of a first order partial differential equation and is a consequence of particle concentration gradients which arise in the pits. By viewing pits as particle funnels, we are able to relate the gradient of pit walls to absorbtion probability and particle bias.

  5. 41. THE BEAR PIT (OLD SIDE DINING ROOM). THE ETCHINGS ...

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

    41. THE BEAR PIT (OLD SIDE DINING ROOM). THE ETCHINGS ON THE CEILING BEAMS AND COLUMNS OF PARK WILDLIFE ARE ORIGINAL TO THE OLD SIDE DINING ROOM. THE SIDE DINING ROOM WAS DESIGNED AND BUILT BY ROBERT REAMER IN 1927. IN 1962 WHEN IT WAS CONVERTED INTO THE BEAR PIT A WALL WAS ADDED BETWEEN THE THREE COLUMNS THAT SEPARATE THIS ROOM FROM THE MAIN DINING ROOM. THE ORIGINAL BEAR PIT ETCHINGS DEPICTING BEARS TENDING BAR AND PLAYING THE PIANO WERE MOUNTED ON THE WALL BETWEEN THE COLUMNS. - Old Faithful Inn, 900' northeast of Snowlodge & 1050' west of Old Faithful Lodge, Lake, Teton County, WY

  6. Plutonium: Aging mechanisms and weapon pit lifetime assessment

    NASA Astrophysics Data System (ADS)

    Martz, Joseph C.; Schwartz, Adam J.

    2003-09-01

    Planning for future refurbishment and manufacturing needs of the U.S. nuclear weapons complex critically depends on credible estimates for component lifetimes. One of the most important of these components is the pit, that portion of the weapon that contains the fissile element plutonium. The U.S. government has proposed construction of a new Modern Pit Facility, and a key variable in planning both the size and schedule for this facility is the minimum estimated lifetime for stockpile pits. This article describes the current understanding of aging effects in plutonium, provides a lifetime estimate range, and outlines in some detail methodology that will improve this estimate over the next few years.

  7. Retaining latch for a water pit gate

    DOEpatents

    Beale, A.R.

    1997-11-18

    A retaining latch is described for use in a hazardous materials storage or handling facility to adjustably retain a water pit gate in a gate frame. A retaining latch is provided comprising a latch plate which is rotatably mounted to each end of the top of the gate and a recessed opening, formed in the gate frame, for engaging an edge of the latch plate. The latch plate is circular in profile with one side cut away or flat, such that the latch plate is D-shaped. The remaining circular edge of the latch plate comprises steps of successively reduced thickness. The stepped edge of the latch plate fits inside a recessed opening formed in the gate frame. As the latch plate is rotated, alternate steps of the latch plate are engaged by the recessed opening. When the latch plate is rotated such that the flat portion of the latch plate faces the recessed opening in the gate frame, there is no connection between the opening and the latch plate and the gate is unlatched from the gate frame. 4 figs.

  8. Molten salt corrosion of SiC: Pitting mechanism

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.; Smialek, J. L.

    1985-01-01

    Thin films of Na2SO4 and Na2CO3 at 1000 C lead to severe pitting of sintered alpha-SiC. These pits are important as they cause a strength reduction in this material. The growth of product layers is related to pit formation for the Na2CO3 case. The early reaction stages involve repeated oxidation and dissolution to form sodium silicate. This results in severe grain boundary attack. After this a porous silica layer forms between the sodium silicate melt and the SiC. The pores in this layer appear to act as paths for the melt to reach the SiC and create larger pits.

  9. BOILER SHOP, NORTH END, WITH DROP PIT IN FOREGROUND AND ...

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

    BOILER SHOP, NORTH END, WITH DROP PIT IN FOREGROUND AND SP 2902 PASSENGER CAR UNDER RESTORATION, LOOKING SOUTHEAST. - Southern Pacific, Sacramento Shops, Boiler Shop, 111 I Street, Sacramento, Sacramento County, CA

  10. 14. INTERIOR, INSPECTION PITS AND OVERHEAD CATWALKS, FACING WEST ...

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

    14. INTERIOR, INSPECTION PITS AND OVERHEAD CATWALKS, FACING WEST - Delaware, Lackawanna & Western Railroad Freight & Rail Yard, Multiple Unit Light Inspection Shed, New Jersey Transit Hoboken Terminal Rail Yard, Hoboken, Hudson County, NJ

  11. 17. INTERIOR, INSPECTION PITS, OVERHEAD CRANE SUPPORT AND CAR JACKING ...

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

    17. INTERIOR, INSPECTION PITS, OVERHEAD CRANE SUPPORT AND CAR JACKING PADS, FACING EAST - Delaware, Lackawanna & Western Railroad Freight & Rail Yard, Multiple Unit Light Inspection Shed, New Jersey Transit Hoboken Terminal Rail Yard, Hoboken, Hudson County, NJ

  12. 15. INTERIOR, INSPECTION PITS, OVERHEAD CATWALKS AND OVERHEAD CRANE SUPPORT, ...

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

    15. INTERIOR, INSPECTION PITS, OVERHEAD CATWALKS AND OVERHEAD CRANE SUPPORT, FACING WEST - Delaware, Lackawanna & Western Railroad Freight & Rail Yard, Multiple Unit Light Inspection Shed, New Jersey Transit Hoboken Terminal Rail Yard, Hoboken, Hudson County, NJ

  13. 6. VIEW LOOKING NORTHWEST SHOWING COUNTERWEIGHT PIT, RACK AND PINION ...

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

    6. VIEW LOOKING NORTHWEST SHOWING COUNTERWEIGHT PIT, RACK AND PINION GEAR (NORTH ABUTMENT). - Chicago River Bascule Bridge, Wabash Avenue, Spanning Chicago River at North Wabash Avenue, Chicago, Cook County, IL

  14. CHICKEN COOP BEHIND FENCED YARD AND (REAR) OF BARBEQUE PIT, ...

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

    CHICKEN COOP BEHIND FENCED YARD AND (REAR) OF BARBEQUE PIT, LOOKING NORTH - Irvine Ranch Agricultural Headquarters, Carillo Tenant House, Southwest of Intersection of San Diego & Santa Ana Freeways, Irvine, Orange County, CA

  15. BARBEQUE PIT AND PLAYHOUSE IN (REAR) YARD, LOOKING SOUTH ...

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

    BARBEQUE PIT AND PLAYHOUSE IN (REAR) YARD, LOOKING SOUTH - Irvine Ranch Agricultural Headquarters, Carillo Tenant House, Southwest of Intersection of San Diego & Santa Ana Freeways, Irvine, Orange County, CA

  16. 32. DETAIL VIEW OF CAMERA PIT SOUTH OF LAUNCH PAD ...

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

    32. DETAIL VIEW OF CAMERA PIT SOUTH OF LAUNCH PAD WITH CAMERA AIMED AT LAUNCH DECK; VIEW TO NORTHEAST. - Cape Canaveral Air Station, Launch Complex 17, Facility 28402, East end of Lighthouse Road, Cape Canaveral, Brevard County, FL

  17. CONSTRUCTION PROGRESS PHOTO SHOWING EXCAVATION PIT FOR MAIN PROCESSING BUILDING ...

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

    CONSTRUCTION PROGRESS PHOTO SHOWING EXCAVATION PIT FOR MAIN PROCESSING BUILDING (CPP-601) LOOKING SOUTH. INL PHOTO NUMBER NRTS-50-693. Unknown Photographer, 1950 - Idaho National Engineering Laboratory, Idaho Chemical Processing Plant, Fuel Reprocessing Complex, Scoville, Butte County, ID

  18. 23. Closer perspective view from the southwest. An archaeological pit ...

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

    23. Closer perspective view from the southwest. An archaeological pit is located under the center first-floor window. - John Bartram House & Garden, House, 54th Street & Lindbergh Boulevard, Philadelphia, Philadelphia County, PA

  19. 14. DETAIL SOUTHWEST OF TURBINE PIT SHOWING INTAKE GATE (IN ...

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

    14. DETAIL SOUTHWEST OF TURBINE PIT SHOWING INTAKE GATE (IN CLOSED POSITION) - Middle Creek Hydroelectric Dam, On Middle Creek, West of U.S. Route 15, 3 miles South of Selinsgrove, Selinsgrove, Snyder County, PA

  20. 15. VIEW SOUTHEAST OF HYDROELECTRIC GENERATING FACILITY SHOWING TURBINE PIT ...

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

    15. VIEW SOUTHEAST OF HYDROELECTRIC GENERATING FACILITY SHOWING TURBINE PIT TO RIGHT AND POWERHOUSE TO LEFT - Middle Creek Hydroelectric Dam, On Middle Creek, West of U.S. Route 15, 3 miles South of Selinsgrove, Selinsgrove, Snyder County, PA

  1. 13. VIEW OF BARBECUE PIT, FACING EAST. (BUILDING 132 IS ...

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

    13. VIEW OF BARBECUE PIT, FACING EAST. (BUILDING 132 IS IN BACKGROUND ON RIGHT.) - Fort McPherson, World War II Station Hospital, Structures, Bordered by Hardee & Thorne Avenues & Howe Street, Atlanta, Fulton County, GA

  2. 22. VIEW SOUTH, INTERIOR OF SOUTH PIT, SHOWING FINAL STEP ...

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

    22. VIEW SOUTH, INTERIOR OF SOUTH PIT, SHOWING FINAL STEP IN GEARING THAT DRIVES OPERATING WHEEL, WITH HYDRAULIC SHAFT BRAKE - Mystic River Bridge, Spanning Mystic River at U.S. Route 1, Groton, New London County, CT

  3. 105-KW Sandfilter Backwash Pit sludge volume calculation

    SciTech Connect

    Dodd, E.N. Jr.

    1995-02-10

    The volume of sludge contained in the 100-KW Sandfilter Backwash Pit (SFBWP) was calculated from depth measurements of the sludge, pit dimension measurements and analysis of video tape recordings taken by an underwater camera. The term sludge as used in this report is any combination of sand, sediment, or corrosion products visible in the SFBWP area. This work was performed to determine baseline volume for use in determination of quantities of uranium and plutonium deposited in the pit from sandfilter backwashes. The SFBWP has three areas where sludge is deposited: (1) the main pit floor, (2) the transfer channel floor, and (3) the surfaces and structures in the SFBWP. The depths of sludge and the uniformity of deposition varies significantly between these three areas. As a result, each of the areas was evaluated separately. The total volume of sludge determined was 3.75 M{sup 3} (132.2 ft{sup 3}).

  4. 1. AERIAL VIEW SHOWING ARCHEOLOGICAL EXCAVATIONS OF LOCOMOTIVE PITS IN ...

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

    1. AERIAL VIEW SHOWING ARCHEOLOGICAL EXCAVATIONS OF LOCOMOTIVE PITS IN FORMER ERECTING SHOP. MACHINE SHOP IS BUILDING AT RIGHT. - Grant Locomotive Works, Market & Spruce Streets, Paterson, Passaic County, NJ

  5. 94. Detail view of ground level at platform, pit "C", ...

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

    94. Detail view of ground level at platform, pit "C", elevator doors in closed position, exhaust vent on left, and elevator platform controls on right, looking northwest - Nike Missile Battery MS-40, County Road No. 260, Farmington, Dakota County, MN

  6. 16. Detail of drainage pits inside east half (1892 part) ...

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

    16. Detail of drainage pits inside east half (1892 part) of main section of roundhouse. View to southeast. - Duluth & Iron Range Rail Road Company Shops, Roundhouse, Southwest of downtown Two Harbors, northwest of Agate Bay, Two Harbors, Lake County, MN

  7. 54. Photocopied August 1978. INTERIOR OF A TAIL PIT OR ...

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

    54. Photocopied August 1978. INTERIOR OF A TAIL PIT OR TAIL RACE AT THE EAST END OF THE POWER HOUSE, SEPTEMBER 17, 1900. THE PRE-MOULDED BLOCKS WHICH FORMED THE SIDE WALLS AND THE ARCHED FOREBAY WALL ARE CLEARLY VISIBLE. THE MONOLITHIC FLOOR OF THE TAIL PIT, HOWEVER, HAS NOT YET BEEN POURED: NEITHER HAS THE MONOLITHIC ARCHED ROOF. (75) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  8. Sensitivity Analysis of Inverse Methods in Eddy Current Pit Characterization

    NASA Astrophysics Data System (ADS)

    Aldrin, John C.; Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H.; Knopp, Jeremy S.

    2010-02-01

    A sensitivity analysis was performed for a pit characterization problem to quantify the impact of potential sources for variation on the performance of inverse methods. Certain data processing steps, including careful feature extraction, background clutter removal and compensation for variation in the scan step size through the tubing, were found to be critical to achieve good estimates of the pit depth and diameter. Variance studied in model probe dimensions did not adversely affect performance.

  9. Corrosion pitting and environmentally assisted small crack growth

    PubMed Central

    Turnbull, Alan

    2014-01-01

    In many applications, corrosion pits act as precursors to cracking, but qualitative and quantitative prediction of damage evolution has been hampered by lack of insights into the process by which a crack develops from a pit. An overview is given of recent breakthroughs in characterization and understanding of the pit-to-crack transition using advanced three-dimensional imaging techniques such as X-ray computed tomography and focused ion beam machining with scanning electron microscopy. These techniques provided novel insights with respect to the location of crack development from a pit, supported by finite-element analysis. This inspired a new concept for the role of pitting in stress corrosion cracking based on the growing pit inducing local dynamic plastic strain, a critical factor in the development of stress corrosion cracks. Challenges in quantifying the subsequent growth rate of the emerging small cracks are then outlined with the potential drop technique being the most viable. A comparison is made with the growth rate for short cracks (through-thickness crack in fracture mechanics specimen) and long cracks and an electrochemical crack size effect invoked to rationalize the data. PMID:25197249

  10. Corrosion pitting and environmentally assisted small crack growth.

    PubMed

    Turnbull, Alan

    2014-09-01

    In many applications, corrosion pits act as precursors to cracking, but qualitative and quantitative prediction of damage evolution has been hampered by lack of insights into the process by which a crack develops from a pit. An overview is given of recent breakthroughs in characterization and understanding of the pit-to-crack transition using advanced three-dimensional imaging techniques such as X-ray computed tomography and focused ion beam machining with scanning electron microscopy. These techniques provided novel insights with respect to the location of crack development from a pit, supported by finite-element analysis. This inspired a new concept for the role of pitting in stress corrosion cracking based on the growing pit inducing local dynamic plastic strain, a critical factor in the development of stress corrosion cracks. Challenges in quantifying the subsequent growth rate of the emerging small cracks are then outlined with the potential drop technique being the most viable. A comparison is made with the growth rate for short cracks (through-thickness crack in fracture mechanics specimen) and long cracks and an electrochemical crack size effect invoked to rationalize the data. PMID:25197249

  11. One dimensional Linescan x-ray detection of pits in fresh cherries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The presence of pits in processed cherries is a concern for both processors and consumers, in many cases causing injury and potential lawsuits. While machines used for pitting cherries are extremely efficient, if one or more plungers in a pitting head become misaligned, a large number of pits may p...

  12. 43 CFR 3603.11 - What rights pertain to users of community pits?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false What rights pertain to users of community... DISPOSAL Community Pits and Common Use Areas Disposal of Materials-Community Pits and Common Use Areas § 3603.11 What rights pertain to users of community pits? BLM's designation of a community pit site,...

  13. 7 CFR 52.802 - Grades of frozen red tart pitted cherries.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Grades of frozen red tart pitted cherries. 52.802... of Frozen Red Tart Pitted Cherries Product Description and Grades § 52.802 Grades of frozen red tart pitted cherries. (a) “U.S. Grade A” (or “U.S. Fancy”) is the quality of frozen red tart pitted...

  14. 7 CFR 52.802 - Grades of frozen red tart pitted cherries.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Grades of frozen red tart pitted cherries. 52.802... of Frozen Red Tart Pitted Cherries Product Description and Grades § 52.802 Grades of frozen red tart pitted cherries. (a) “U.S. Grade A” (or “U.S. Fancy”) is the quality of frozen red tart pitted...

  15. Real-time methods for non-destructive detection of pits in fresh cherries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The presence of pits in processed cherries is a concern for both processors and consumers, in many cases causing injury and potential lawsuits. While machines used for pitting cherries are extremely efficient, if one or more plungers in a pitting head become misaligned, a large number of pits may p...

  16. Crack Initiation from Corrosion Pit in Three Aluminum Alloys Under Ambient and Saltwater Environments

    NASA Astrophysics Data System (ADS)

    Sabelkin, V.; Misak, H. E.; Perel, V. Y.; Mall, S.

    2016-04-01

    Corrosion-pit-to-crack transition behaviors of three aluminum alloys using two pit configurations were investigated under ambient and saltwater environments. Fatigue stress ranges for crack initiation from a through-pit were less than that from a corner-pit in both environments in all three materials, while stress intensity factor ranges showed the opposite trend. Further, stress ranges or stress intensity factor ranges for crack initiation were less in saltwater than that in ambient environment for both pit configurations. Fatigue damage mechanisms in a test environment were similar for both pit configurations in all three materials. An empirical relationship is proposed to estimate pit-to-crack transition fatigue cycles.

  17. Multiphysics Modeling for Dimensional Analysis of a Self-Heated Molten Regolith Electrolysis Reactor for Oxygen and Metals Production on the Moon and Mars

    NASA Technical Reports Server (NTRS)

    Dominguez, Jesus A.; Sibille, Laurent

    2010-01-01

    The technology of direct electrolysis of molten lunar regolith to produce oxygen and molten metal alloys has progressed greatly in the last few years. The development of long-lasting inert anodes and cathode designs as well as techniques for the removal of molten products from the reactor has been demonstrated. The containment of chemically aggressive oxide and metal melts is very difficult at the operating temperatures ca 1600 C. Containing the molten oxides in a regolith shell can solve this technical issue and can be achieved by designing a self-heating reactor in which the electrolytic currents generate enough Joule heat to create a molten bath. In a first phase, a thermal analysis model was built to study the formation of a melt of lunar basaltic regolith irradiated by a focused solar beam This mode of heating was selected because it relies on radiative heat transfer, which is the dominant mode of transfer of energy in melts at 1600 C. Knowing and setting the Gaussian-type heat flux from the concentrated solar beam and the phase and temperature dependent thermal properties, the model predicts the dimensions and temperature profile of the melt. A validation of the model is presented in this paper through the experimental formation of a spherical cap melt realized by others. The Orbitec/PSI experimental setup uses an 3.6-cm diameter concentrated solar beam to create a hemispheric melt in a bed of lunar regolith simulant contained in a large pot. Upon cooling, the dimensions of the vitrified melt are measured to validate the thermal model. In a second phase, the model is augmented by multiphysics components to compute the passage of electrical currents between electrodes inserted in the molten regolith. The current through the melt generates Joule heating due to the high resistivity of the medium and this energy is transferred into the melt by conduction, convection and primarily by radiation. The model faces challenges in two major areas, the change of phase as

  18. Nobody’s perfect: can irregularities in pit structure influence vulnerability to cavitation?

    PubMed Central

    Plavcová, Lenka; Jansen, Steven; Klepsch, Matthias; Hacke, Uwe G.

    2013-01-01

    Recent studies have suggested that species-specific pit properties such as pit membrane thickness, pit membrane porosity, torus-to-aperture diameter ratio and pit chamber depth influence xylem vulnerability to cavitation. Despite the indisputable importance of using mean pit characteristics, considerable variability in pit structure within a single species or even within a single pit field should be acknowledged. According to the rare pit hypothesis, a single pit that is more air-permeable than many neighboring pits is sufficient to allow air-seeding. Therefore, any irregularities or morphological abnormalities in pit structure allowing air-seeding should be associated with increased vulnerability to cavitation. Considering the currently proposed models of air-seeding, pit features such as rare, large pores in the pit membrane, torus extensions, and plasmodesmatal pores in a torus can represent potential glitches. These aberrations in pit structure could either result from inherent developmental flaws, or from damage caused to the pit membrane by chemical and physical agents. This suggests the existence of interesting feedbacks between abiotic and biotic stresses in xylem physiology. PMID:24273549

  19. Multiphysics Modeling for Dimensional Analysis of a Self-Heated Molten Regolith Electrolysis Reactor for Oxygen and Metals Production on the Moon and Mars

    NASA Technical Reports Server (NTRS)

    Dominguez, Jesus; Sibille, Laurent

    2010-01-01

    The technology of direct electrolysis of molten lunar regolith to produce oxygen and molten metal alloys has progressed greatly in the last few years. The development of long-lasting inert anodes and cathode designs as well as techniques for the removal of molten products from the reactor has been demonstrated. The containment of chemically aggressive oxide and metal melts is very difficult at the operating temperatures ca. 1600 C. Containing the molten oxides in a regolith shell can solve this technical issue and can be achieved by designing a self-heating reactor in which the electrolytic currents generate enough Joule heat to create a molten bath.

  20. Stem pitting Citrus tristeza virus predominantly transmitted by the brown citrus aphid from mixed infections containing non-stem pitting and stem pitting isolates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus tristeza virus (CTV) is a phloem-limited closterovirus that produces a variety of symptoms in various Citrus spp. One of these symptoms is stem pitting (SP). SP does not occur in all Citrus spp. but when it does it may cause low tree vigor, decline and an economically-significant reduction ...

  1. Stochastic nature of clathrin-coated pit assembly

    NASA Astrophysics Data System (ADS)

    Banerjee, Anand; Berezhkovskii, Alexander; Nossal, Ralph

    2013-03-01

    Clathrin-mediated endocytosis is a complex process through which eukaryotic cells internalize various macromolecules (cargo). The process occurs via the formation of invaginations on the cell membrane, called clathrin-coated pits (CCPs). The dynamics of CCP formation shows remarkable variability. After initiation, a fraction of CCPs, called ``productive pits'', bind to cargo and then grow and mature into clathrin-coated vesicles (CCVs). In contrast, a large fraction of CCPs, called ``abortive pits'', fail to bind to cargo, grow only up to intermediate sizes and then disassemble. There is notable heterogeneity in the lifetimes of both productive and abortive pits. We propose a stochastic model of CCP dynamics to explain these experimental observations. Our model includes a kinetic scheme for CCP assembly and a related functional form for the dependence of free energy of a CCP on its size. Using this model, we calculate the lifetime distribution of abortive pits (via Monte Carlo simulation) and show that the distribution fits experimental data very well. By fitting the data we determine the free energy of CCP formation and show that CCPs without cargo are energetically unstable. We also suggest a mechanism by which cargo binding stabilizes CCPs and facilitates their growth.

  2. Pitting corrosion of iron in weakly alkaline chloride solutions

    SciTech Connect

    Makar, G.L.; Tromans, D.

    1996-04-01

    Chloride-induced pitting corrosion of iron at pH 10.5 and 25 C was examined by conducting quasi-steady-state (potentiostatic) polarization experiments in borate-buffered 0.1 M sodium chloride solutions with buffer concentrations from 0 M to 0.075 M. Values of the film breakdown potential (E{sub b}) were scattered at each buffer concentration, and the scatter band moved to higher potentials with increasing concentrations, indicating increased resistance to pitting. Consistent with this, pitting did not always occur at the higher buffer concentrations. E{sub b} measurements, optical and electron microscopy, X-ray microanalysis, and supplementary polarization experiments in lower-pH borate solutions suggested pitting in the iron -Cl{sup {minus}} system initiated within occluded regions, such as matrix-inclusion interfaces and exposed voids, where pH control was lost because of an inadequate local supply of buffer species. Pitting behavior was consistent with a mechanism dominated by mass transport, in which the presence of Cl{sup {minus}} prevented buffering of occluded regions by the borate specie H{sub 2}BO{sub 3}{sup {minus}}, allowing the ph to be driven into an acidic domain where the solubilities of ferrous hydroxide and ferric hydroxide are high.

  3. Initiation and propagation of a single pit on stainless steel using a local probe technique.

    PubMed

    Heurtault, Stéphane; Robin, Raphaël; Rouillard, Fabien; Vivier, Vincent

    2015-01-01

    Experiments about single pit initiation and propagation were performed on 316L stainless steel with the aim to determine the pitting corrosion behaviour for nuclear waste containers. The experimental setup permits to control the pit development at will and to create reproducible single pits in three dimensions. Radial and deep evolutions of a disc shaped pit were studied for propagation times of up to 10 hours. These evolutions were used to determine what limiting mechanism takes place during long-term pit propagation. Special attention has been paid to the chloride ion action on pitting. A minimum chloride concentration was found to be necessary in the bulk electrolyte to support pit propagation. The existence of a critical pit depth of 230 μm was also underlined. PMID:25901720

  4. Gnamma Pit Growth: Insights from Wind Tunnel Experiments and Numerical Modeling

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Schmeeckle, M. W.

    2014-12-01

    Gnamma pit is an Australian aboriginal term for weathering pit, and its formation is controlled by a mix of mineral decay and eolian processes. Prior literature suggests that two processes limit pit growth: decay along grain boundaries sufficient to allow mineral detachment; and eolian events sufficient to deflate accumulate minerals. However, prior literature contains little empirical data on the nature of these processes. Our research focuses on developing a better understanding of wind thresholds that deflate particles from pits. A set of wind-tunnel tests with a range of weathering pit shapes and grus particle sizes explored the wind threshold needed to deflate particles in different situations. An empirical equation expresses the way to estimate wind the speed threshold via pit depth and particle size. With this equation, the threshold for evacuating particles in the pit can be estimated by measuring the pit depth and smallest particles in the weathering pit, that indicates that the wind speed would not exceed this value when this pit is still active. We also developed a computational fluid dynamics model to investigate the distribution of wall shear stress. Ultimately, there exists some potential to utilize our refined understanding of gnamma pits as an indicator of paleo-wind intensity in pit locations where the accumulated sediment can be dated (e.g., by OSL) and such filled pits excavated to understand the paleo-wind conditions that would have once allowed the growth of such a pit.

  5. A global inventory of central pit craters on the Moon: Distribution, morphology, and geometry

    NASA Astrophysics Data System (ADS)

    Xiao, Zhiyong; Zeng, Zuoxun; Komatsu, Goro

    2014-01-01

    The origin of central pit craters on the Moon has long been an enigma, and a primary reason is that their geographic distribution and morphometric characteristics were unknown. We investigated a global inventory of lunar central pit craters using high-resolution image and topography data obtained from the Lunar Reconnaissance Orbiter. 56 certain and 35 probable central pit craters are found on both the lunar maria and highlands. The certain pit craters are ˜9-57 km in diameter. The average diameter ratio between the central pits and their parent craters is ˜0.12 and the average depth/diameter ratio for the central pits is ˜0.072. With irregular-shaped rims, the central pits have conical profiles and some have flat floors. The central pits occur on both crater floors and central peaks. The floor pits are generally larger, deeper, and with more irregular shape compared with summit pits. Both the summit and floor pit craters have formed in every lunar stratigraphic epoch from Nectarian to Copernican. Target properties of background terrains affect the morphology and size of central pits, but they do not determine whether or not a central pit forms during a cratering event. The lunar central pits may have formed by deformation of central peaks caused by some mechanical processes during or soon after the cratering process of their parent craters.

  6. Generation of a pulsed high-current low-energy beam in a plasma electron source with a self-heated cathode

    NASA Astrophysics Data System (ADS)

    Gavrilov, N. V.; Men'shakov, A. I.

    2016-05-01

    The transition of a low-current discharge with a self-heated hollow cathode to a high-current discharge is studied, and stability conditions for the latter in the pulsed-periodic mode with a current of 0.1-1.0 kA, pulse width of 0.1-1.0 ms, and a pulse repetition rate of 0.1-1.0 kHz are determined. The thermal conditions of the hollow cathode are analyzed, and the conclusion is drawn that the emission current high density is due to pulsed self-heating of the cathode's surface layer. Conditions for stable emission from a plasma cathode with a grid acting as a plasma boundary using such a discharge are found at low accelerating voltage (100-200 eV) and a gas pressure of 0.1-0.4 Pa. The density of the ion current from a plasma generated by a pulsed beam with a current of 100 A is found to reach 0.1 A/cm2. Probe diagnostics data for the emitting and beam plasmas in the electron source are presented, and a mechanism behind the instability of electron emission from the plasma is suggested on their basis.

  7. Nutritional quality evaluation of eighteen date pit varieties.

    PubMed

    Habib, Hosam M; Ibrahim, Wissam H

    2009-01-01

    The pits from date palm fruits (Phoenix dactylifera L.) are nutrient dense but the nutrient composition across varieties has not been extensively studied. In the present study, 18 leading varieties of date pits from date fruits cultivated in the United Arab Emirates (Khalas, Barhe, Lulu, Shikat alkahlas, Sokkery, Bomaan, Sagay, Shishi, Maghool, Sultana, Fard, Maktoomi, Naptit Saif, Jabri, Kodary, Dabbas, Raziz and Shabebe) were analyzed and compared for their chemical and physical properties. Dietary fiber, proximate analysis, micronutrients, and physical properties (weight, length, and density) were determined. Significant differences (P<0.05) in the measured parameters were observed among the different varieties. The results show that date pits, depending on the variety, contain significant but quite variable amounts of macronutrients and micronutrients, but all varieties are excellent sources of dietary fiber and may therefore serve as important constituents of functional foods. PMID:18925479

  8. Pitting corrosion monitoring with an improved electrochemical noise technique

    SciTech Connect

    Chen, J.F.; Shadley, J.; Rybicki, E.F.

    1999-11-01

    The electrochemical emission spectroscopy (EES) technique is a newly developed on-line corrosion monitoring technique, which is capable of detecting localized corrosion as well as measuring uniform corrosion. The main difference between this technique and the traditional electrochemical noise technique is the use of an inert microelectrode to sense the current signal from a working electrode instead of using two identical working electrodes to generate the current signal. In this paper, the ability of the EES technique is evaluated for pitting corrosion monitoring. Pitting corrosion is generated on three systems: stainless steel types 304 and 316 in aerated 3% NaCl solution at 50 C and stainless steel type 304 in 6% FeCl{sub 3} solution at room temperature. In all cases, the on-set of pitting corrosion is clearly indicated in both potential and current spectrums. A parameter called the corrosion admittance, which is defined in the EES technique, is capable of indicating instantaneous localized corrosion activities.

  9. State Waste Discharge Permit application: 200-W Powerhouse Ash Pit

    SciTech Connect

    Atencio, B.P.

    1994-06-01

    As part of the Hanford Federal Facility Agreement and Consent Order negotiations; the US Department of Energy, Richland Operations Office, the US Environmental Protection Agency, and the Washington State Department of Ecology agreed that liquid effluent discharges to the ground on the Hanford Site which affect groundwater or have the potential to affect groundwater would be subject to permitting under the structure of Chapter 173-216 (or 173-218 where applicable) of the Washington Administrative Code, the State Waste Discharge Permit Program. This document constitutes the State Waste Discharge Permit application for the 200-W Powerhouse Ash Pit. The 200-W Powerhouse Ash Waste Water discharges to the 200-W Powerhouse Ash Pit via dedicated pipelines. The 200-W Powerhouse Ash Waste Water is the only discharge to the 200-W Powerhouse Ash Pit. The 200-W Powerhouse is a steam generation facility consisting of a coal-handling and preparation section and boilers.

  10. State Waste Discharge Permit application: 200-E Powerhouse Ash Pit

    SciTech Connect

    Atencio, B.P.

    1994-06-01

    As part of the Hanford Federal Facility Agreement and Consent Order negotiations, the US Department and Energy, Richland Operations Office, the US Environmental Protection Agency, and the Washington State Department of Ecology agreed that liquid effluent discharges to the ground on the Hanford Site which affect groundwater or have the potential to affect groundwater would be subject to permitting under the structure of Chapter 173-216 (or 173-218 where applicable) of the Washington Administrative Code, the State Waste Discharge Permit Program. This document constitutes the State Waste Discharge Permit application for the 200-E Powerhouse Ash Pit. The 200-E Powerhouse Ash Waste Water discharges to the 200-E Powerhouse Ash Pit via dedicated pipelines. The 200-E Ash Waste Water is the only discharge to the 200-E Powerhouse Ash Pit. The 200-E Powerhouse is a steam generation facility consisting of a coal-handling and preparation section and boilers.

  11. Fukushima Nuclear Accident Recorded in Tibetan Plateau Snow Pits

    PubMed Central

    Wang, Ninglian; Wu, Xiaobo; Kehrwald, Natalie; Li, Zhen; Li, Quanlian; Jiang, Xi; Pu, Jianchen

    2015-01-01

    The β radioactivity of snow-pit samples collected in the spring of 2011 on four Tibetan Plateau glaciers demonstrate a remarkable peak in each snow pit profile, with peaks about ten to tens of times higher than background levels. The timing of these peaks suggests that the high radioactivity resulted from the Fukushima nuclear accident that occurred on March 11, 2011 in eastern Japan. Fallout monitoring studies demonstrate that this radioactive material was transported by the westerlies across the middle latitudes of the Northern Hemisphere. The depth of the peak β radioactivity in each snow pit compared with observational precipitation records, suggests that the radioactive fallout reached the Tibetan Plateau and was deposited on glacier surfaces in late March 2011, or approximately 20 days after the nuclear accident. The radioactive fallout existed in the atmosphere over the Tibetan Plateau for about one month. PMID:25658094

  12. Pit Distribution Design for Computer-Generated Waveguide Holography

    NASA Astrophysics Data System (ADS)

    Yagi, Shogo; Imai, Tadayuki; Ueno, Masahiro; Ohtani, Yoshimitsu; Endo, Masahiro; Kurokawa, Yoshiaki; Yoshikawa, Hiroshi; Watanabe, Toshifumi; Fukuda, Makoto

    2008-02-01

    Multilayered waveguide holography (MWH) is one of a number of page-oriented data multiplexing holographies that will be applied to optical data storage and three-dimensional (3D) moving images. While conventional volumetric holography using photopolymer or photorefractive materials requires page-by-page light exposure for recording, MWH media can be made by employing stamping and laminating technologies that are suitable for mass production. This makes devising an economical mastering technique for replicating holograms a key issue. In this paper, we discuss an approach to pit distribution design that enables us to replace expensive electron beam mastering with economical laser beam mastering. We propose an algorithm that avoids the overlapping of even comparatively large adjacent pits when we employ laser beam mastering. We also compensate for the angular dependence of the diffraction power, which strongly depends on pit shape, by introducing an enhancement profile so that a diffracted image has uniform intensity.

  13. Pit and fissure sealant: review of the literature.

    PubMed

    Simonsen, Richard J

    2002-01-01

    For this literature review of pit and fissure sealant, 1,465 references were selected by a search for "sealants" on PubMed. References were limited to dental journals and papers in the English language. The search comprised papers from 1971 to October 2001. Additional papers of historical significance prior to 1971 were added from memory and from reference lists published in early papers. This paper reviewed the literature on pit and fissure sealants under the following subheadings: (1) laboratory studies, (2) clinical technique and tooth preparation, (3) etching time, (4) auxiliary application of pit and fissure sealant, (5) retention and caries prevention, (6) fluoride used with sealants and fluoride-containing sealant, (7) glass ionomer materials as sealants, (8) options in sealant: filled vs unfilled; colored vs clear; autocure vs light-initiated, (9) sealant placed over caries in a therapeutic manner, (10) cost effectiveness of sealant application, (11) underuse of pit and fissure sealant, (12) the estrogenicity issue, (13) use of an intermediate bonding layer to improve retention, (14) new developments and projections, and (15) summary and conclusions. From a careful and thorough review of peer-reviewed publications on pit and fissure sealant, it is clear that sealants are safe, effective and underused (at least underused in the United States). Pit and fissure sealant is best applied to high-risk populations by trained auxiliaries using sealant that incorporates the benefit of an intermediate bonding layer, applied under the rubber dam or with some alternative short-term, but effective, isolation technique, onto an enamel surface that has been cleaned with an air polishing technique and etched with 35% phosphoric acid for 15 seconds. The dental profession awaits with enthusiasm, and some impatience, the incorporation of dentin-bonding technology into the development of a modern, more durable, resin-based sealant. PMID:12412954

  14. Upper Extremity Injuries in NASCAR Drivers and Pit Crew

    PubMed Central

    Wertman, Gary; Gaston, R. Glenn; Heisel, William

    2016-01-01

    Background: Understanding the position-specific musculoskeletal forces placed on the body of athletes facilitates treatment, prevention, and return-to-play decisions. While position-specific injuries are well documented in most major sports, little is known about the epidemiology of position-specific injuries in National Association for Stock Car Automobile Racing (NASCAR) drivers and pit crew. Purpose: To investigate position-specific upper extremity injuries in NASCAR drivers and pit crew members. Study Design: Descriptive epidemiological study. Methods: A retrospective chart review was performed to assess position-specific injuries in NASCAR drivers and pit crew members. Included in the study were patients seen by a single institution between July 2003 and October 2014 with upper extremity injuries from race-related NASCAR events or practices. Charts were reviewed to identify the diagnosis, mechanism of injury, and position of each patient. Results: A total of 226 NASCAR team members were treated between July 2003 and October 2014. Of these, 118 injuries (52%) occurred during NASCAR racing events or practices. The majority of these injuries occurred in NASCAR changers (42%), followed by injuries in drivers (16%), carriers (14%), jack men (11%), fuel men (9%), and utility men (8%). The majority of the pit crew positions are at risk for epicondylitis, while drivers are most likely to experience neuropathies, such as hand-arm vibration syndrome. The changer sustains the most hand-related injuries (42%) on the pit crew team, while carriers commonly sustain injuries to their digits (29%). Conclusion: Orthopaedic injuries in NASCAR vary between positions. Injuries in NASCAR drivers and pit crew members are a consequence of the distinctive forces associated with each position throughout the course of the racing season. Understanding these forces and position-associated injuries is important for preventive measures and facilitates diagnosis and return-to-play decisions

  15. Relationship Between Foveal Cone Specialization and Pit Morphology in Albinism

    PubMed Central

    Wilk, Melissa A.; McAllister, John T.; Cooper, Robert F.; Dubis, Adam M.; Patitucci, Teresa N.; Summerfelt, Phyllis; Anderson, Jennifer L.; Stepien, Kimberly E.; Costakos, Deborah M.; Connor, Thomas B.; Wirostko, William J.; Chiang, Pei-Wen; Dubra, Alfredo; Curcio, Christine A.; Brilliant, Murray H.; Summers, C. Gail; Carroll, Joseph

    2014-01-01

    Purpose. Albinism is associated with disrupted foveal development, though intersubject variability is becoming appreciated. We sought to quantify this variability, and examine the relationship between foveal cone specialization and pit morphology in patients with a clinical diagnosis of albinism. Methods. We recruited 32 subjects with a clinical diagnosis of albinism. DNA was obtained from 25 subjects, and known albinism genes were analyzed for mutations. Relative inner and outer segment (IS and OS) lengthening (fovea-to-perifovea ratio) was determined from manually segmented spectral domain-optical coherence tomography (SD-OCT) B-scans. Foveal pit morphology was quantified for eight subjects from macular SD-OCT volumes. Ten subjects underwent imaging with adaptive optics scanning light ophthalmoscopy (AOSLO), and cone density was measured. Results. We found mutations in 22 of 25 subjects, including five novel mutations. All subjects lacked complete excavation of inner retinal layers at the fovea, though four subjects had foveal pits with normal diameter and/or volume. Peak cone density and OS lengthening were variable and overlapped with that observed in normal controls. A fifth hyper-reflective band was observed in the outer retina on SD-OCT in the majority of the subjects with albinism. Conclusions. Foveal cone specialization and pit morphology vary greatly in albinism. Normal cone packing was observed in the absence of a foveal pit, suggesting a pit is not required for packing to occur. The degree to which retinal anatomy correlates with genotype or visual function remains unclear, and future examination of larger patient groups will provide important insight on this issue. PMID:24845642

  16. Shiftable belt conveyor systems in open pit mining

    SciTech Connect

    Weissflog, J.

    1983-10-01

    During recent years the open-cast mining scene in the USA has altered and the first steps towards continuous haulage have been made. The authors are of the opinion that this development will continue in the future due to the fact that governments, not only the American Government, have introduced environmental laws and regulations which require very high standards of reclamation of mined-out areas. To improve the strip mining system and to improve and to meet reclamation standards, many mining companies now start to operate with cross pit conveying or round the pit conveying systems.

  17. 53. Photocopied August 1978. DERRICKS AND GENERAL VIEW OF PIT ...

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

    53. Photocopied August 1978. DERRICKS AND GENERAL VIEW OF PIT WALLS, POWER HOUSE, NOVEMBER 7, 1900. THE MONOLITHIC BASES OF THESE WALLS PRIOR TO THE ERECTION OF THE PRE-MOULDED BLOCKS APPEAR TO THE RIGHT. ASSEMBLED WALLS ARE ON THE LEFT. NOTE THAT THE MONOLITHIC FLOORS FOR THE TAIL PITS HAVE BEEN POURED IN THE FIVE RACES ON THE RIGHT, BUT NOT IN THE THREE CLOSEST TO THE ALREADY-ASSEMBLED WALLS. (103) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  18. Ablation layers to prevent pitting in laser peening

    DOEpatents

    Hackel, Lloyd A

    2016-08-09

    A hybrid ablation layer that comprises a separate under layer is applied to a material to prevent pitting resulting from laser peening. The underlayer adheres to the surface of the workpiece to be peened and does not have bubbles and voids that exceed an acceptable size. One or more overlayers are placed over and in contact with the underlayer. Any bubbles formed under the over layers are insulated from the surface to be peened. The process significantly reduces the incidence of pits on peened surfaces.

  19. Development of an automated pit packaging system for Pantex

    SciTech Connect

    Fahrenholtz, J.C.

    1997-09-01

    Sandia National Laboratories is developing a system that uses robots to package pits at Pantex in the AT-400A pit storage and transportation container. This report will give an overview of the AT-400A packaging process, and the parts of the overall AT-400A packaging operation that will be performed robotically. The process employed to move from development in the laboratory at Sandia to production use at Pantex will be described. Finally, important technology components being developed for and incorporated into the robotic system will be described. 7 refs., 9 figs.

  20. In Situ Characterization of Pitting Corrosion of Stainless Steel by a Scanning Electrochemical Microscopy

    NASA Astrophysics Data System (ADS)

    Dong, C. F.; Luo, H.; Xiao, K.; Li, X. G.; Cheng, Y. F.

    2012-03-01

    In this work, a scanning electrochemical microscopy (SECM) was used to characterize in situ the metastable and stable pitting processes occurring on a stainless steel in the chloride solution. It was found that metastable pitting would occur on the steel that was at corrosion potential and passive potential. The positive shift of potential would enhance the metastable pitting current. On application of a potential exceeding pitting potential, the pit became stabilized and maintained a continuous growth. The SECM is capable of detecting the microdissolution event and provides a "visual" observation of the pitting processes.

  1. Sudden onset of pitting corrosion on stainless steel as a critical phenomenon.

    PubMed

    Punckt, C; Bölscher, M; Rotermund, H H; Mikhailov, A S; Organ, L; Budiansky, N; Scully, J R; Hudson, J L

    2004-08-20

    Stainless steels undergo a sharp rise in pitting corrosion rate as the potential, solution concentration, or temperature is changed only slightly. We report experiments using real-time microscopic in situ visualizations that resolve the nucleation and evolution of individual pits during the transition. They suggest that the sudden onset of corrosion is explained by an explosive autocatalytic growth in the number of metastable pits and that stabilization of individual pits takes place only later. This finding agrees with a theoretical approach treating the onset of pitting corrosion as a cooperative critical phenomenon resulting from interactions among metastable pits, and it extends perspectives on the control and prevention of corrosion onset. PMID:15326349

  2. Design Principles for Broad-Spectrum Protein-Crystal Nucleants with Nanoscale Pits

    NASA Astrophysics Data System (ADS)

    van Meel, Jacobus A.; Sear, Richard P.; Frenkel, Daan

    2010-11-01

    Growing high-quality crystals is a bottleneck in the determination of protein structures by x-ray diffraction. Experiments find that materials with a disordered pitted surface seed the growth of protein crystals. Here we report computer simulations of rapid crystal nucleation in nanoscale pits. Nucleation is rapid, as the crystal forms in pits that have filled with liquid via capillary condensation. Surprisingly, we find that pits whose surfaces are rough are better than pits with crystalline surfaces; the roughness prevents the growing crystal from trying to conform to the pit surface and becoming strained.

  3. New Insights into Central Pit Crater Formation on Mars and Ganymede

    NASA Astrophysics Data System (ADS)

    Barlow, Nadine G.

    2009-09-01

    We are conducting a comparison study of central pit craters on Mars and Ganymede, the first study of these features since the 1980's. We utilize THEMIS VIS and daytime IR data for Mars and Galileo and Voyager imagery for Ganymede. Our global study includes 1604 central pit craters on Mars (912 floor pits and 692 summit pits) and 471 central pit craters on Ganymede (all floor pits). Differences in central pit crater size between the two bodies are likely due to the difference in surface gravity and larger pits on Ganymede may be due to the icier crustal conditions. Central pit craters show no regional or terrain preferences in occurrence on either body. These craters show a range of preservational states, indicating the conditions favoring pit formation have existed throughout the histories of both Mars and Ganymede. No variation in excavation depth is seen with preservational state. Pit diameters display a linear relationship with crater diameter on Mars and for craters <70-km-diameter on Ganymede. Craters between 70 and 130 km on Ganymede display much larger pits relative to crater diameter while those >130 km are much smaller, suggesting the influence of thermal gradients and/or ice phase changes at depth. Central pit craters on Mars display no updomed floors, unlike their counterparts on Ganymede, indicating low (about 20%) concentrations of target ice can produce central pits. Projectile impact velocities are probably responsible for formation of central pit craters adjacent to non-pit craters of similar size and age. We have used the results of this study to constrain formation models for central pit craters. The central peak collapse and subsurface liquid layer models are not supported by this study. Our results are consistent with the target volatilization model, which also has new modeling support.

  4. The effects of pitting on fatigue crack nucleation in 7075-T6 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Ma, LI; Hoeppner, David W.

    1994-01-01

    A high-strength aluminum alloy, 7075-T6, was studied to quantitatively evaluate chemical pitting effects of its corrosion fatigue life. The study focused on pit nucleation, pit growth, and fatigue crack nucleation. Pitting corrosion fatigue experiments were conducted in 3.5 percent NaCl aqueous solution under constant amplitude sinusoidal loading at two frequencies, 5 and 20 Hz. Smooth and unnotched specimens were used in this investigation. A video recording system was developed to allow in situ observation of the surface changes of the specimens during testing. The results indicated that pitting corrosion considerably reduces the fatigue strength by accelerating fatigue crack nucleation. A metallographic examination was conducted on the specimens to evaluate the nature of corrosion pits. First, the actual shapes of the corrosion pits were evaluated by cross-sectioning the pits. Secondly, the relation between corrosion pits and microstructure was also investigated. Finally, the possibility of another corrosion mechanism that might be involved in pitting was explored in this investigation. The fractography of the tested specimens showed that corner corrosion pits were responsible for fatigue crack nucleation in the material due to the associated stress concentration. The pits exhibited variance of morphology. Fatigue life for the experimental conditions appeared to be strongly dependent on pitting kinetics and the crack nucleation stage.

  5. Electric-field dependence of electron drift velocity in 4H-SiC

    NASA Astrophysics Data System (ADS)

    Ivanov, P. A.; Potapov, A. S.; Samsonova, T. P.; Grekhov, I. V.

    2016-09-01

    Room temperature isothermal forward current-voltage characteristics of mesa-epitaxial 4H-SiC Schottky diodes were measured at high electric fields (beyond 105 V/cm) in the 34-μm thick n-base doped at 1 × 1015 cm-3. The effect of diode self-heating on current was minimized when using single 4-ns pulses. The analytical formula was derived for the dependence of electron drift velocity on electric field along c-axis.

  6. Rotary Drill Operator. Open Pit Mining Job Training Series.

    ERIC Educational Resources Information Center

    Savilow, Bill

    This training outline for rotary drill operators, one in a series of eight outlines, is designed primarily for company training foremen or supervisors and for trainers to use as an industry-wide guideline for heavy equipment operator training in open pit mining in British Columbia. Intended as a guide for preparation of lesson plans both for…

  7. Pitted and Hybrid Morningglory Accessions Have Variable Tolerance to Glyphosate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Greenhouse studies were conducted to investigate the variability in tolerance to glyphosate among 38 accessions of pitted morningglory collected from several southern United States. Glyphosate at 420 g ae/ha was applied postemergence to plants at 4- to 5-leaf stage and control was visually estimated...

  8. Olanzapine-induced tender pitting pre-tibial edema.

    PubMed

    Mathan, Kaliaperumal; Muthukrishnan, Venkatesan; Menon, Vikas

    2015-01-01

    Antipsychotic-induced edema is uncommonly encountered in clinical practice. We report a case of tender pitting pre-tibial edema with olanzapine in a woman with no medical comorbidities. The peculiar distribution of edema resulted in diagnostic confusion necessitating specific investigations. Eventually, the edema resolved following complete stoppage of the drug, but caused distress to the patient and the caregiver. PMID:25969664

  9. 7. View of turbine pit at an exciter unit showing ...

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

    7. View of turbine pit at an exciter unit showing servo-motor heads (foreground and background at left) with piston rods bolted to the operating ring of the turbine gate (foreground and background at center). View to northeast. - Holter Hydroelectric Facility, Dam & Power House, End of Holter Dam Road, Wolf Creek, Lewis and Clark County, MT

  10. Track Dozer Operator. Open Pit Mining Job Training Series.

    ERIC Educational Resources Information Center

    British Columbia Dept. of Education, Victoria.

    This training outline for track dozer operators, one in a series of eight outlines, is designed primarily for company training foremen or supervisors and for trainers to use as an industry-wide guideline for heavy equipment operator training in open pit mining in British Columbia. Intended as a guide for preparation of lesson plans both for…